JPH1190619A - Method and device for joining metallic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase joining strength more than a conventional level and also to prevent generation of cracks, in the case of joining a valve seat to the circumferential part (joining face part) of a port opening in a cylinder head main body. SOLUTION: A brazing filler metal layer 7 is formed preliminarily on the surface of a valve seat 3 through a diffusion joining layer 5 between the brazing filler metal and the valve seat 3. While the valve seat 3 and a cylinder head main body 2 are pressurized, energizing and heating are performed at an initial current value until the valve seat 3 is embedded at a prescribed joining position, a fusion reaction layer 6 of the brazing filler metal and the cylinder head body 2 is formed and while the fused brazing filler metal is discharged from the joining face between the both members 2, 3, the both members are joined in a liquid phase diffused state through the diffusion joining layer 5 and the fusion reaction layer 6. Subsequently, the energizing and the heating are performed at slow cooling current value smaller than the initial current value, the both members 2, 3 are cooled slowly and the temperature difference is made smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a method and an apparatus for joining metal members formed by diffusion joining a first metal member and a second metal member.

[0002]

2. Description of the Related Art Conventionally, as a method of joining metal members to each other, for example, in a case where a valve seat is joined to an opening edge of an intake and exhaust port of a cylinder head body in an engine cylinder head, shrink fitting is used. Is well known.

Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. H8-100701, a valve seat and an Al-based cylinder head body are brazed and joined with an Al-Zn-based brazing material and a fluoride-based flux. It has been proposed.

Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 58-13481, a method is known in which metal members are joined to each other by resistance welding utilizing contact resistance heating at a joint surface of both members. In this resistance welding, as shown in, for example, Japanese Patent Application Laid-Open No. 6-58116, a metal is infiltrated into holes of a valve seat formed of a sintered material, thereby generating heat inside the sintered material. Reducing the amount of heat to increase the amount of heat generated at the joint surface,
For example, as disclosed in Japanese Patent Application Laid-Open No. Hei 8-270499, it has been proposed to form a film on the surface of a valve seat and to melt the film at the time of coupling with a cylinder head body.

Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. H8-200148, a molten reaction layer is formed while forming a plastically deformable layer on the joint surface of the cylinder head body with the valve seat and the cylinder head body. It has been proposed that solid-phase diffusion bonding (pressure welding) be performed without the need.

[0006]

However, in the method of joining metal members by shrink fitting as in the above-mentioned conventional example,
In order to reliably prevent the metal members to be separated from falling off and to withstand the tightening force at the time of shrink fitting, the metal members to be bonded must be relatively large. For this reason, in the cylinder head, the thickness and width of the valve seat become large, and there is a limit in reducing the port interval or increasing the throat diameter. Furthermore, since the heat insulating layer exists between the valve seat and the cylinder head body, there is a problem that the thermal conductivity is low and the temperature in the vicinity of the valve and the valve seat cannot be effectively reduced.

Further, in the method of joining metal members by brazing or resistance welding, although the thermal conductivity between the two members can be improved, the joining strength is basically low, and the joining between the valve seat and the cylinder head is basically low. It is difficult to employ for joining. In particular, in the joining method by brazing, it is necessary to heat in a furnace for a long time, so it is not possible to respond to in-line processing, the heat treatment effect is lost in aluminum members that have been heat-treated in advance, and the brazing material for aluminum casting Has a problem that the melting point is low and the heat resistance is low.

On the other hand, the solid-phase diffusion bonding method has the advantage that the valve seat can be made much smaller than the bonding method by shrink fit, and the degree of freedom in engine design can be improved. Since solid-state diffusion bonding is used, strict control is required for bonding conditions such as pressure and current. In particular, in the joining of the Al-based cylinder head body and the Fe-based valve seat, it is necessary to suppress the generation of a brittle intermetallic compound of Fe-Al and to diffuse the atoms of Fe and Al, which is contradictory. In addition, it is necessary to set joining conditions more strictly.

The present invention has been made in view of the above points, and an object of the present invention is to improve the above-mentioned conventional joining method when joining a first metal member to a second metal member. Thus, it is possible to easily obtain a metal member having a higher bonding strength than the conventional one in a short time.

[0010]

In order to achieve the above object, according to the present invention, when the first metal member and the second metal member are energized and heated, a relatively large initial current value is applied for a predetermined time, Thereafter, the current is heated with a small current value (slow cooling current value) to reduce the temperature difference between the two members after the current is stopped.

Specifically, the invention according to claim 1 is a method for joining metal members by diffusion joining a first metal member to a second metal member having a different coefficient of thermal expansion from that of the first metal member. Then, while applying pressure while the first metal member is in contact with the joint surface of the second metal member, the two members are energized and heated at a predetermined initial current value for a predetermined time. The two members are energized and heated with a slow cooling current value smaller than the current value.

As a result, the temperature of both members rises due to current heating at the initial current value, and diffusion bonding starts. At this time, the temperature difference between the two members increases due to the difference in heat capacity between the two members. Then, after a lapse of a predetermined time, the energizing current changes to a gradual cooling current value smaller than the initial current value, so that the calorific value of both members decreases, and the temperature of the member changes from the higher temperature member to the lower member. Heat dissipation proceeds. As a result, the temperature difference between the two members is reduced, so that the generation of thermal stress due to the difference in the coefficient of thermal expansion can be suppressed. Therefore, after the energization is stopped, the occurrence of cracks in the metal member due to thermal stress is effectively prevented.

According to a second aspect of the present invention, in the method for bonding metal members according to the first aspect, the first metal member is provided with a predetermined time for energizing and heating at the initial current value after starting the energizing heating. Until it is displaced to the joining position.

[0014] With this configuration, since the first metal member is energized and heated by the initial current value until it is displaced to the predetermined bonding position, the first metal member and the second metal member can be securely bonded. it can. After that, since the energization heating is performed with a slow cooling current value smaller than the initial current value, the temperature difference between the two members can be smoothly reduced by gradually cooling the respective members.

According to a third aspect of the present invention, in the method for joining metal members according to the first aspect, the predetermined time for energizing and heating at the initial current value is set to a predetermined fixed time after starting the energizing heating. It is.

This makes it possible to easily set a predetermined time for energizing and heating at the initial current value, and to easily and reliably execute energizing and heating at the initial current value and the slow cooling current value.

According to a fourth aspect of the present invention, in the method of joining metal members according to any one of the first and second aspects, the first metal member is pressed and energized to heat the first metal member. Embedded in the joint surface of the second metal member,
The predetermined time during which the heating is performed with the initial current value is defined as a period from the start of the heating to the time when the first metal member is embedded in the predetermined bonding position with respect to the second metal member.

As a result, the two members are diffusion-bonded so that the first metal member is embedded in the second metal member by the current heating at the initial current value. Then, when the first metal member is embedded to a predetermined joining position,
The energizing current changes from the initial current value to a slow cooling current value smaller than the initial current value. As a result, while the first metal member is maintained at the joining position, the two members are gradually cooled. Therefore, highly accurate bonding is performed.

According to a fifth aspect of the present invention, in the method of bonding a metal member according to the fourth aspect, the initial current value is a current value for promoting the embedding of the first metal member into the second metal member. On the other hand, the slow cooling current value is set to a current value that suppresses the embedding of the first metal member into the second metal member.

Thus, the current-carrying heating based on the initial current value is used for embedding the first metal member in the second metal member. On the other hand, current heating by slow cooling current value is
Used for slow cooling of both members. Since the electric heating by the slow cooling current value suppresses the embedding of the first metal member, it is possible to reliably prevent the first metal member from being excessively embedded in the second metal member during the slow cooling. Can be. Therefore, the temperature difference between the two members can be reduced while maintaining the positions of the two members properly.

According to a sixth aspect of the present invention, in the method for joining metal members according to any one of the first to fifth aspects, the first metal member is a ring-shaped member and the second metal member is a ring-shaped member. Has a bonding surface surrounding the outer peripheral portion of the ring-shaped member.

Thus, the thermal stress of the first metal member, which tends to expand and contract in the radial direction, is alleviated by the current heating with the slow cooling current value, and vertical cracks of the first metal member are prevented. Therefore, the effects of the inventions of claims 1 to 5 are remarkably exhibited.

According to a seventh aspect of the present invention, in the method for joining metal members according to any one of the first to sixth aspects, the first metal member is made of an Fe-based material, and the second metal member is made of an Fe-based material. Is made of an Al-based material.

[0024] Thus, the occurrence of cracks due to the difference in the coefficient of thermal expansion does not occur, and the Fe-based material and Al
A metal member made of a base material is obtained.

According to an eighth aspect of the present invention, in the method of joining metal members according to any one of the first to seventh aspects, the melting point of the first metal member on the surface of the first metal member is higher than that of the two metal members. A brazing material layer is formed via a diffusion layer between the low brazing material and the first metal member, and the first metal member and the second metal member are connected to each other by energization between the two members. The diffusion layer of the brazing material and the second metal member is formed by heat and pressure, and the molten brazing material is joined in a liquid phase diffusion state through the diffusion layers while discharging the molten brazing material from between the joining surfaces of the two members. It is decided to do.

With this, the first metal member and the second metal member are liquid-phase diffusion-bonded while the brazing material is discharged and the two diffusion layers are interposed therebetween, so that the surface of the second metal member is oxidized. The coating and the dirt are discharged together with the brazing material, and the two diffusion layers are directly joined without interposing the brazing material layer, and the diffusion between the two layers is further promoted. In addition, since the diffusion is liquid phase diffusion, it is performed extremely quickly. Further, since it is only necessary to set the pressing force and the current value so that the brazing material can be melted and discharged, the condition range in which high joining strength can be obtained is wide. Further, although the melting point of the brazing material is usually low, even if the brazing material is discharged and a little remains, the melting point of the brazing material after joining is changed because the proportion of the brazing material changes due to the formation of the diffusion layer. Can be higher. Therefore,
By the in-line operation, it is possible to obtain a joined metal member having high joining strength and heat resistance higher than that of the brazing material used.

According to a ninth aspect of the present invention, in the method for joining metal members according to the eighth aspect, the first metal member is formed of
The second metal member is made of an Al-based material, and the brazing material is made of a Zn-based material.

Thus, since the melting point of the Zn-based brazing material is relatively low, the brazing material can be easily and reliably melted and discharged. In addition, the Zn-based brazing material easily forms the Fe-based first metal member and the Fe-Zn diffusion layer, and the Al-based second metal member and the Al-Zn diffusion layer, respectively. Furthermore, since the bonding is performed via the two diffusion layers, the generation of a brittle intermetallic compound of Fe-Al can be effectively prevented. Therefore, an optimum combination of materials can be obtained for the bonding method described in claim 8.

According to a tenth aspect of the present invention, in the method for bonding a metal member according to any one of the eighth and ninth aspects, the diffusion layer between the first metal member and the brazing material is formed of the first metal. The member is formed by applying ultrasonic vibration to the surface of the member and coating the brazing material.

As a result, the oxide film and the plating layer on the surface of the first metal member are destroyed by the cavitation effect of the ultrasonic wave, so that the brazing material is rubbed against the surface of the first metal member. The brazing material can be more reliably diffused to the first metal member side than the method using the appropriate friction. Further, a post-process for removing the flux as in the case of performing brazing using the flux is unnecessary. Therefore, the diffusion layer can be reliably formed by a simple method, and a bonding metal member having higher bonding strength can be obtained.

The eleventh aspect of the present invention is the first aspect of the present invention.
0, the first metal member is brought into contact with the second metal member before the first metal member is contacted with a high electrical conductivity material inside the first metal member. It is to be infiltrated.

As a result, the high electrical conductivity material becomes the first material.
Since the infiltration into the holes inside the metal member is effected, the same effect as forging can be obtained, and the heat generation inside the first metal member can be suppressed during energization to effectively melt the brazing material.
Therefore, the joining strength of the joining metal member can be effectively improved.

According to the twelfth aspect of the present invention,
In the method for joining metal members according to any one of the first to fifth aspects, the diffusion joining between the first metal member and the second metal member is performed by:
This is performed by plastically flowing the joint surface of the second metal member.

By doing so, the oxide film on the surface of the second metal member is effectively destroyed and discharged from the joint surface, so that the brazing material can be surely diffused to the second metal member side. It is not necessary to particularly protect the surface of the second metal member. On the other hand, the plastic flow of the second metal member is
When the first metal member and the second metal member are pressurized, the pressing can be easily performed by utilizing the pressing force, and no special means is required. Therefore, the diffusion layer can be reliably formed by a simple method, and the joining strength of the joining metal member can be further improved.

According to a thirteenth aspect of the present invention, there is provided a metal member joining apparatus for diffusing and joining a first metal member to a second metal member having a different coefficient of thermal expansion from the first metal member. A pressing means for bringing the first metal member into contact with the joining surface of the second metal member, and pressing both members so that pressure is applied to the joining surface; and from one of the two members to the other. An electrode for flowing a current flowing through the joint surface, a welding power supply for supplying a current between the electrodes when the two members are pressed by the pressing means, and a value of the current supplied by the welding power supply. Switching means for switching from the initial current value to a slow cooling current value smaller than the initial current value.

Thus, a joining apparatus for realizing the joining method according to the first aspect is obtained, and the same operation and effect as those of the first aspect are obtained.

According to a fourteenth aspect of the present invention, in the metal member joining apparatus according to the thirteenth aspect, the switching means comprises a first switch.
When the metal member is displaced to a predetermined joining position, the initial current value is switched to the slow cooling current value.

Thus, a bonding apparatus for realizing the bonding method according to the second aspect is obtained, and the same operation and effect as those of the second aspect are obtained.

According to a fifteenth aspect of the present invention, in the metal member joining apparatus according to the thirteenth aspect, the switching means changes the initial current value to the gradual cooling current when a predetermined time has elapsed from the start of energization. It is set to switch to the value.

Thus, a bonding apparatus for realizing the bonding method according to the third aspect is obtained, and the same operation and effect as the invention according to the third aspect are obtained.

The invention described in claim 16 is the invention according to claims 13 to
15. In the apparatus for joining metal members according to any one of 15, the welding power supply means energizes and heats the first metal member in a state where the first metal member is pressurized by the pressurizing means, thereby welding the first metal member to the first metal member. The switching means includes a position detecting means for detecting an embedding position of the metal member to be joined, and the first metal member is embedded in a predetermined embedding position. When it is detected that the initial current value is changed to the slow cooling current value, the setting is made.

Thus, a joining apparatus for realizing the joining method according to the fourth aspect is obtained, and the same operation and effect as the invention according to the fourth aspect are obtained.

According to a seventeenth aspect of the present invention, in the metal member bonding apparatus according to the sixteenth aspect, the initial current value is a current value for promoting the embedding of the first metal member into the second metal member. On the other hand, the slow cooling current value is set to a current value that suppresses the embedding of the first metal member into the second metal member.

Thus, a joining apparatus for realizing the joining method according to the fifth aspect is obtained, and the same operation and effect as the invention according to the fifth aspect are obtained.

The invention according to claim 18 is the invention according to claims 13 to
17. In the apparatus for joining metal members according to any one of items 17, the welding power supply means presses the first metal member, on which the diffusion layer and the brazing material layer are formed in advance, to the joint surface of the second metal member. By applying current and heating in a state of being pressurized, a diffusion layer of the brazing material and the second metal member is formed, and while the molten brazing material is discharged from between the joining surfaces of the two members, the two members are separated by the above-described method. It is configured to be joined in a liquid phase diffusion state via both diffusion layers.

As a result, a bonding apparatus for realizing the bonding method described in claim 8 is obtained, and the same operation and effect as the invention described in claim 8 are obtained.

The invention according to claim 19 is the invention according to claims 13 to
18. The apparatus for joining metal members according to any one of items 18, wherein the welding power supply means includes a joining surface portion of the second metal member in a state where the first metal member is in contact with the joining surface of the second metal member. Is configured to be electrically heated in a state where the two members are pressurized by a pressurizing means so that the two members are diffusion-bonded while plastically flowing.

As a result, a joining apparatus for realizing the joining method according to the twelfth aspect is obtained, and the same operation and effect as the invention according to the twelfth aspect can be obtained.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a joining method and a joining apparatus to which the present invention is applied will be described (basic modes 1 and 2), and then an embodiment of the present invention (embodiment 1).
4) will be described.

(Basic Mode 1) First, as a target to which the present invention is applied, a bonding method and a bonding apparatus for diffusing and bonding a cylinder head 1 of an engine to a cylinder head body 2 by energizing and heating at a constant current value are described. It will be described as.

FIG. 1 shows a main part of a cylinder head 1 of an engine as a joining metal member according to a basic mode 1. This cylinder head 1 is provided in a cylinder head main body 2 as a base member (second metal member). The substantially ring-shaped valve seats 3, 3,... Are located at the peripheral edges of the openings of the four intake and exhaust ports 2b, 2b,.
(First metal member) joined as described later. The peripheral edges of the openings of the ports 2b are arranged in a substantially square shape when viewed from the lower side of the cylinder head 1, and the peripheral edges of the openings are the joint surfaces 2a with the valve seats 3.

The inner peripheral surface of each of the valve seats 3 is formed as a valve abutting surface 3c, and is formed in a tapered shape whose diameter decreases upward along the shape of the upper surface of the valve. The outer peripheral surface of each valve seat 3 is the first joint surface 3a with the cylinder head body 2, and is formed in a tapered shape like the inner peripheral surface. Further, the upper surface portion of each valve seat 3 is a second joint surface portion 3b with the cylinder head main body 2, and is inclined upward toward the inner peripheral side.

Each of the valve seats 3 is a sintered material made of an Fe-based material, and a Cu-based material as a high electrical conductivity material is infiltrated therein. This valve seat 3
First and second joint surfaces 3 with the cylinder head body 2
a, 3b, as schematically shown in FIG.
System material (about 95% by weight of Zn component and about 5% by weight of Al
A diffusion bonding layer 5 is formed between the brazing material made of the component (3) and the valve seat 3. That is, the diffusion bonding layer 5
Is made of Fe—Zn formed by diffusing the Zn component of the brazing material to the valve seat 3 side.

On the other hand, the cylinder head main body 2 is made of an Al-based material, and a fusion reaction layer 6 between the brazing material and the cylinder head main body 2 is formed on a joint surface 2a of the cylinder head main body 2 with each valve seat 3. Is formed. That is, the molten reaction layer 6 is made of Al—Zn formed by the liquid phase diffusion of the Zn component of the brazing material into the cylinder head body 2 in a molten state.

The valve seat 3 and the cylinder head main body 2 are connected to the diffusion bonding layer 5 and the molten reaction layer 6.
The diffusion bonding layer 5 and the molten reaction layer 6 have a total thickness of 1.0 μm or less. In FIG. 2, a brazing material layer 7 is formed between the diffusion bonding layer 5 and the molten reaction layer 6.
Is extremely small and can be considered to be practically negligible.

A method of manufacturing the cylinder head 1 by joining the valve seats 3 to the peripheral portions (joining surfaces 2a) of the ports 2b of the cylinder head main body 2 in the cylinder head 1 having the above-described structure will be described. In the following manufacturing process, the top and bottom of the cylinder head body 2 and the valve seat 3 are reversed.

First, the valve seat 3 is manufactured by sintering Fe-based material powder. At this time, as shown in FIG. 3, the valve seat 3 is designed to withstand the pressing force at the time of joining the valve seat 3 and the cylinder head main body 2.
The inner peripheral side and the upper side (the lower side in FIG. 1) are formed so as to be thicker. That is, at this stage, the valve contact surface portion 3c is not formed, and the inner peripheral surface is formed to extend straight upward and the upper surface is formed to be substantially horizontal. Further, the taper angle (θ1 in FIG. 3) of the first joint surface 3a with the cylinder head body 2 is about 0.52 rad.
(30 °), and the inclination angle (θ2 in FIG. 3) of the second joint surface 3b is formed at about 0.26 rad (15 °). That is, the taper angle θ1 of the first joint surface 3a
Is too small, it is easy to embed the valve seat 3 in the cylinder head body 2, but the oxide film destruction effect on the joint surface 2a of the cylinder head body 2 is reduced. Since the embedding becomes difficult and the outermost diameter of the valve seat 3 becomes too large to make it possible to narrow the interval between the two ports 2b, 2b, it is set to about 0.52 rad (30 °).

Then, a ring having substantially the same diameter as that of the valve seat 3 is produced by sintering a powder of a Cu-based material, and the ring is placed on the upper surface of the sintered valve seat 3 to be heated. Then, the Cu-based material is infiltrated into the interior of the valve seat 3 by being melted. Thereafter, the first and second joint surfaces 3a,
A Cu plating layer (about 2 μm) is applied to the entire surface including 3b from the viewpoint of preventing formation of an oxide film.

Subsequently, as schematically shown in FIG. 5A, a brazing material layer 7 is formed on the bonding surface of the valve seat 3 with the diffusion bonding layer 5 interposed therebetween. In order to form the brazing material layer 7 and the diffusion bonding layer 5 on the valve seat 3, the surface of the valve seat 3 in the brazing material bath is coated with a brazing material by applying ultrasonic vibration (ultrasonic plating). That is, FIG.
As shown in FIG. 1, one end of the diaphragm 11 is connected to the ultrasonic oscillator 12.
The valve seat 3 is immersed in a brazing material bath 14 in a bottomed container 13 with the valve seat 3 placed on the upper surface of the other end of the diaphragm 11. In this state, when ultrasonic vibration is applied to the valve seat 3 from the ultrasonic oscillator 12 via the diaphragm 11, a Cu plating layer on the surface of the valve seat 3 and a slight amount are formed by cavitation by the ultrasonic waves. The oxide film is destroyed, and the Zn component of the brazing material diffuses toward the valve seat 3 to form a diffusion bonding layer 5 made of Fe—Zn, and a brazing material layer 7 is formed on the surface side of the diffusion bonding layer 5. Is done. This makes it possible to form the diffusion bonding layer 5 more reliably and easily than a method using mechanical friction in which a brazing material is rubbed against the surface of the valve seat 3. The ultrasonic plating conditions include, for example, a brazing material bath temperature of 400 ° C., an ultrasonic output of 400 W,
The ultrasonic vibration application time may be set to 20 seconds.

Next, the valve seat 3 is connected to the port 2 of the cylinder head body 2 which has been manufactured in advance by casting or the like.
b, which is joined to the periphery of the opening, that is, to the joint surface 2a with the valve seat 3. At this time, the joining surface portion 2a of the cylinder head main body 2 is different from the shape at the time of joining completion (the same shape as the first and second joining surface portions 3a and 3b of the valve seat 3) as shown in FIG. , About 0.79 rad (45 °).

In order to join the valve seat 3 to the joining surface 2a of the cylinder head main body 2, as shown in FIG. 7, a joining device 20 obtained by improving a commercially available projection welding machine is used. The joining device 20 has a substantially U-shaped support main body 21, and the upper and lower horizontal portions 21a and 21b of the support main body 21 are cantilevered and supported by only one vertical portion 21c. The side opposite to the portion 21c is open. A pressure cylinder 22 is provided below the upper horizontal portion 21a of the support body 21, and a cylinder rod 2 of the pressure cylinder 22 is provided below the pressure cylinder 22.
3, a substantially cylindrical upper electrode 24 made of Cu that is vertically movable on the same axis as the cylinder rod 23 is provided. On the other hand, on the upper side of the lower horizontal portion 21b, a lower electrode 25 made of Cu is provided so as to face the upper electrode 24 via a moving table 27, and a cylinder is provided on the obliquely upper surface of the lower electrode 25. The head main body 2 can be placed so that the joint surface 2 a is located above the cylinder head main body 2. The horizontal position of the movable base 27 with respect to the lower horizontal portion 21b and the inclination of the upper surface of the lower electrode 25 can be adjusted, and the center axis of the joint surface 2a for joining the valve seat 3 is vertical and The adjustment is made so as to substantially coincide with the central axis of the electrode 24.

The upper and lower electrodes 24 and 25 are respectively connected to a welding power source 26 housed in the vertical portion 21c of the support main body 21, and a valve is provided on the joint surface 2a of the cylinder head main body 2 on the upper surface of the lower electrode 25. With the seat 3 placed thereon, the upper electrode 24 is brought into contact with the upper surface of the valve seat 3 to press the valve seat 3 and the cylinder head body 2 by the pressurizing cylinder 22 while turning the welding power source 26 on.
When N, current flows from the valve seat 3 to the cylinder head main body 2. The lower surface of the upper electrode 24 that contacts the upper surface of the valve seat 3 includes:
As shown in an enlarged manner in FIG.
A cutout 28 is formed on the opposite side (opening side of the support main body 21) as a non-conductive portion.

The cylinder head main body 2 is placed on the upper surface of the lower electrode 25 of the joining device 20, and the movable base 26 is moved in the horizontal direction so that the central axis of the joining surface 2 a joining the valve seat 3 substantially coincides with the upper electrode 24. After adjusting the position and the inclination of the upper surface of the lower electrode 24, the valve seat 3 is placed on the joint surface 2a. At this time, as shown in FIG. 4A, only the corners of the first and second joint surfaces 3a and 3b of the valve seat 3 are in contact with the joint surface 2a of the cylinder head body 2.

Then, the upper electrode 24 is moved downward by the operation of the pressurizing cylinder 22 so as to contact the upper surface of the valve seat 3, and pressurization of the valve seat 3 and the cylinder head body 2 is started from this state. . This pressure is 294
About 20N (3000 kgf) is desirable. Then, as shown in FIG. 9, while maintaining this pressing force, the welding power source 26 is turned on about 1.5 seconds after the start of pressurization, and the resistance heat generated by energization between the valve seat 3 and the cylinder head body 2 is generated. Melts the brazing material of the brazing material layer 7. This current value is desirably about 70 kA.

At this time, the melting point of the brazing material comprising about 95% by weight of the Zn component and about 5% by weight of the Al component is extremely low at about 380 ° C., as shown in FIG. Further, the joint surface 2a of the cylinder head main body 2 is softened by the resistance heating, and as shown in FIG. 4B, the corner between the first joint surface 3a and the second joint surface 3b of the valve seat 3 is pressurized. The valve seat 3 is buried in the cylinder head body 2 while causing the joint surface 2a of the cylinder head body 2 to plastically flow. As a result, the oxide film on the joint surface portion 2a of the cylinder head body 2 is surely destroyed, and the Zn component of the molten brazing material diffuses in the liquid phase toward the cylinder head body 2 to form the molten reaction layer 6 made of Al-Zn. (See FIG. 5B).

On the other hand, as shown in FIG. 5C, almost all the brazing material of the brazing material layer
And, it is discharged together with the oxide film and the dirt from between the second joint surfaces 3a and 3b and the joint surface 2a of the cylinder head body 2. For this reason, the diffusion bonding layer 5 does not pass through the brazing material layer 7.
And the molten reaction layer 6 are directly joined to each other,
Diffusion between them is further promoted. In addition, the formation of a brittle intermetallic compound of Fe—Al can be effectively prevented through the two layers 5 and 6. Therefore, the valve seat 3 and the cylinder head body 2 are joined in a liquid phase diffusion state via the diffusion joining layer 5 and the molten reaction layer 6,
Its bonding strength is very high. Even if a small amount of the brazing material layer 7 remains, the Zn ratio of the brazing material decreases due to diffusion, and its melting point rises to about 500 ° C. or higher (see FIG. 11). For this reason, after joining, it has heat resistance higher than the melting point of the brazing material used.

Furthermore, since the inside of the valve seat 3 is infiltrated with a Cu-based material having a high electrical conductivity, the pores formed by sintering are filled with the Cu-based material, and a part of the pressure is applied. Is not used to crush the above-mentioned hole, and all of the pressing force is used to directly plastically flow the joint surface portion 2a of the cylinder head body 2 and to discharge the brazing material. The heat generation inside the valve seat 3 can be suppressed, and the brazing material can be effectively melted.

Further, the upper and lower horizontal portions 21a,
The upper and lower horizontal portions 21a, 2b are cantilevered portions.
Due to the bending of 1b, the pressing force is reduced on the opening side of the support body and the contact resistance is increased by that amount, so that the calorific value on the opening side becomes excessive, aluminum is locally melted, and the gap with the valve seat is reduced. May occur. In order to prevent this, as shown in FIGS. 8A and 8B, a notch 28 may be formed on the lower surface of the upper electrode 24 on the opening side of the support main body 21. In this case, the current value is small in portions corresponding to the valve seat 3 and the opening side of the support main body 21 of the cylinder head main body 2. For this reason, there is no possibility that the opening side of the support body 21 in the cylinder head body 2 is locally melted and a gap is formed between the cylinder head body 2 and the valve seat 3. Further, since the central axes of the cylinder rod 23 of the pressurizing cylinder 22 and the upper electrode 24 coincide with each other, the difference in the pressing force of the entire upper electrode 24 and the horizontal axis of the upper electrode The change in the directional position can be reduced, the degree of notch of the notch 28 can be reduced, and the misalignment of the valve seat 3 with respect to the joint surface 2a of the cylinder head main body 2 can be prevented. It should be noted that instead of providing the notch 28, the upper electrode 24
By attaching an insulating member to the lower surface of the cylinder head, local melting of the cylinder head body 2 can be prevented.

Subsequently, when 1.5 to 2.5 seconds have elapsed from the start of energization, the welding power source 26 is turned off to stop energization.
The valve seat 3 is a joint surface 2a of the cylinder head body 2.
(See FIG. 4 (c)).
At this time, the pressurization is continued without stopping. That is, the pressing force is maintained until the molten reaction layer 6 is completely solidified, and the respective joint surfaces 2a, 3a, 3b due to the different thermal expansion rates of the valve seat 3 and the cylinder head body 2
To prevent peeling and cracking.

As shown in FIG. 10, it is more desirable to reduce the pressing force almost simultaneously with stopping the energization. In other words, since there is a high possibility that cracks will occur at the joint surfaces 2a, 3a, 3b immediately after solidification where the deformability becomes small with a large pressing force, the pressing force is reduced to such a level as to follow the shrinkage deformation, and Cracks at the joint surfaces 2a, 3a, 3b are reliably prevented.

Thereafter, the pressure is stopped about 1.5 seconds after the stop of energization, and the joining of the valve seat 3 and the cylinder head body 2 is completed. Subsequently, the same operation is repeated in the same cylinder head main body 2 so that the remaining 3
The valve seats 3 are joined to the two joining surfaces 2a, 2a,.

Finally, the inner peripheral surface and the upper surface of each valve seat 3 are cut to form a valve abutting surface 3c and finished in a predetermined shape. Thus, the cylinder head 1 in which the valve seats 3 are joined to the peripheral portions of the openings of the ports 2b of the cylinder head body 2 is completed.

Therefore, in the first embodiment, the valve seat 3 and the cylinder head body 2 are joined in a liquid phase diffusion state via the diffusion joining layer 5 and the molten reaction layer 6 by the heat and pressure generated by energization. As a result, the cylinder head 1 having high bonding strength and heat resistance higher than that of the brazing filler metal used can be obtained in a short time. Further, since it is only necessary to set the pressing force and the current value so that the brazing material can be melted and discharged, the condition range in which high joining strength can be obtained is wide. In addition, the valve seat 3 can be made much smaller than the joining method by shrink fit,
The distance between the two ports 2b, 2b can be reduced or the throat diameter can be increased. Further, the thermal conductivity in the vicinity of the valve can be improved without forming a heat insulating layer, and the cooling water passage provided between the ports 2b, 2b can be made closer to the valve seat side. The temperature in the vicinity can be effectively reduced. In addition, connect a glow plug or injector to port 2
Even if it is arranged between b and 2b, the wall thickness between them can be sufficiently ensured. Therefore, the performance, reliability and design freedom of the engine can be improved.

In the first embodiment, each of the valve seats 3 is manufactured by sintering and Cu-based material is infiltrated therein. However, the density inside each of the valve seats 3 must be ensured to some extent. If so, it is not necessary to infiltrate. In addition, by forming each valve seat 3 as a sintered forged material obtained by forging after sintering, it is possible to eliminate voids inside the valve seat 3 in the same manner as infiltration. The material can be discharged effectively.

(Basic Mode 2) Next, an embodiment in which the energizing current is a pulse current will be described as Basic Mode 2.

FIG. 12 shows a basic mode 2, which is different from the basic mode 1 in the method of controlling the energization when the valve seat 3 and the cylinder head body 2 are joined.

That is, in this embodiment, a current is not continuously supplied at a constant current value, but a pulse is applied by repeating large and small current values. The current value on the larger side of the pulse current is constant at about 70 kA,
The smaller current value is set to zero. The energizing time of the large current value pulse is 0.25 to 1 second, and the energizing time of the small current value pulse (time during which no current is flowing) is 0.1 to 1 second.
It is about 0.5 seconds. Furthermore, the number of high current value pulses is 3 to
Nine pulses (four pulses in FIG. 12) are desirable. Note that the time from the start of pressurization to the start of energization of the first large current value pulse and the time from the stop of energization of the last large current value pulse to stop of pressurization are 1.5 seconds, which are the same as in the first embodiment.

FIG. 13 shows the temperature change of the valve seat 3 when such pulsed current is applied. That is, since the heat capacity of the valve seat 3 made of the Fe-based material is considerably small, the temperature rise due to the resistance heat generation of the valve seat 3 is remarkable. It is harder to dissipate heat than the upper and lower ends, and the contact resistance between the valve seat 3 and the cylinder head body 2 is high when the first large current value pulse is applied. The temperature at the center is equal to or higher than the A1 transformation point when the first large current value pulse is stopped. At this stage, since the valve seat 3 is almost completely embedded in the cylinder head main body 2, it is possible to completely stop the energization. However, the valve seat 3 is kept at a temperature above the A1 transformation point. Since it is rapidly cooled, its center in the vertical direction is baked and its hardness increases.

Therefore, when the temperature is slightly lowered, the second large current value pulse is applied. At this time, unlike the first energization of the large current value pulse, the contact resistance is reduced by metallurgical bonding, the resistance heating value is reduced, and heat is also released, so even if the current value is the same as the initial value, the temperature is not so much By repeating this process without increasing, the valve seat hardly increases in hardness because it is gradually cooled.

Therefore, in the basic embodiment 2, the temperature of the central portion in the up-down direction of the valve seat 3 is gradually decreased by the pulse current, so that the hardness of the valve seat 3 does not greatly increase. Deterioration in workability when cutting the peripheral surface portion can be prevented. In addition, it is possible to effectively suppress the valve from being easily worn due to the valve contact surface 3c being too hard.

In the second embodiment, the large current value of the pulse current is fixed and the small current value is set to 0. However, the present invention is not limited to this. For example, as shown in FIG. May be reduced stepwise, and as shown in FIG. 14B, the small current value may be set to an intermediate value between the large current value and 0 without being set to 0. Further, as shown in FIG. 14 (c), after applying the first large current value pulse and then applying the small current value pulse (0 in FIG. 14 (c)), the current value is proportional to time. Alternatively, any energization control may be performed as long as the valve seat 3 can be gradually cooled after the energization of the first large current value pulse is stopped.

Further, in order to improve the heat radiation to the upper electrode 24 of the valve seat 3, it is desirable to cool the water through the cooling water in the upper electrode 24. further,
As shown in FIG. 15, a cylindrical projection 31 facing the inner peripheral surface of the valve seat 3 is provided below the upper electrode 24, and is provided on the outer periphery of the projection 31 at substantially equal intervals in the circumferential direction. The cooling water in the upper electrode 24 may be sprayed onto the inner peripheral surface of the valve seat 3 from the plurality of nozzles 32, 32,. This effectively cools the central portion in the vertical direction of the valve seat 3 and can prevent the valve seat 3 from being overheated to the A1 transformation point or higher.

(Embodiment 1) Here, an embodiment of the present invention will be described.

FIG. 16 shows the first embodiment, which is different from the above-described first and second embodiments in the method of controlling the energization when the valve seat 3 and the cylinder head body 2 are joined.

That is, in this embodiment, the joining device 2
0 has a limit switch (not shown) as a position detecting means for detecting the position of the valve seat 3 in the height direction, and the joining is such that the valve seat 3 is almost completely embedded in the cylinder head body 2. The limit switch is configured to operate in the position. When the limit switch is actuated after the energization is started, the current is switched to a constant current value (gradual cooling current value) smaller than the initial current value (approximately 70 kA) at the start of the energization. That is, the limit switch constitutes the switching means in the present invention. Then, the stop of the energization after the switching is performed in a time, and is stopped in 1.5 to 5 seconds from the start of the energization of the initial current value.

A description will be given of the behavior in the case where the energization control of switching to a small current value in a state where the valve seat 3 is almost completely embedded in the cylinder head main body 2 as described above.

First, at the start of energization, as described in the basic embodiment 2, since the temperature of the valve seat 3 is much higher than that of the cylinder head body 2 made of an Al-based material, the coefficient of thermal expansion (linear expansion coefficient) is increased. Is smaller than the cylinder head body 2, but the thermal expansion amount is large. For this reason,
When energization is completely stopped in a state where the valve seat 3 is almost completely embedded in the cylinder head main body 2, since the contraction amount of the valve seat 3 is larger than that of the cylinder head main body 2, tensile thermal stress is generated in the valve seat 3. .

When the current is switched to a current value smaller than the initial current value (gradual cooling current value), the temperature of the valve seat 3 gradually decreases as in the basic embodiment 2. On the other hand, since the temperature of the cylinder head body 2 rises due to the heat from the valve seat 3, the temperature difference between the valve seat 3 and the cylinder head body 2 becomes smaller. If the current supply is stopped in this state, the difference in the amount of contraction becomes small, and the thermal stress generated in the valve seat 3 can be reduced.

Therefore, in the first embodiment, the valve seat 3 is switched to a current value smaller than the initial current value in a state where the valve seat 3 is almost completely embedded in the cylinder head main body 2, so that the valve seat 3 and the cylinder head main body are switched. The difference in the amount of thermal expansion (shrinkage) caused by the difference between the heat capacity and the coefficient of thermal expansion of the second element can be reduced. Therefore,
The tensile thermal stress generated in the valve seat 3 can be reduced, and the occurrence of vertical cracks on the inner peripheral surface can be prevented.

In the first embodiment, the gradual cooling current value after the switching by the operation of the limit switch is fixed. However, the present invention is not limited to this. For example, as shown in FIG. The cold current value may be decreased so as to be proportional to the time. As shown in FIG. 17B, the large current value is changed to the initial current after the limit switch is actuated, as in the basic mode 2. A pulse current smaller than the value may be applied. Furthermore, even if the energization control method is the same as in the basic mode 2,
Similar functions and effects can be obtained.

In the first embodiment, the current value is switched by detecting the position of the valve seat 3 in the height direction by the limit switch. However, a position detecting means such as an optical sensor may be used. May be controlled instead of detecting the time. In this case, 0.25 to 1 second from the start of energization, desirably 0.2
The current value is switched in 5 to 0.5 seconds. During this time, switching is performed in a state where the valve seat 3 is almost completely embedded in the cylinder head body 2.

Further, before joining the valve seat 3 to the cylinder head body 2, the cylinder head body 2 is
It is desirable to preheat to about ° C. By doing so, the temperature difference between them becomes even smaller, and the thermal stress can be kept low. As a result, the valve seat 3
Can reliably be prevented from occurring, and switching of the current value after operation of the limit switch can be made unnecessary. In order to preheat the cylinder head body 2 in this manner, the above-described joining device 20 may be used. That is, the upper and lower electrodes 24 and 25 of the joining device 20 are replaced with carbon electrodes, and the welding power source is turned on with the cylinder head body 2 sandwiched between the electrodes 24 and 25 to perform preheating. . At this time, since both electrodes 24 and 25 are made of carbon, self-heating is large and the cylinder head body 2 can be efficiently preheated. In this way, it is possible to cope with inlining.

Also, as shown in FIG. 18, an upper surface tapered portion 3 d whose height increases toward the inner peripheral surface is provided on the upper portion of the valve seat 3, while the valve seat 3 is provided below the upper electrode 24. A conical concave portion 34 into which the upper surface tapered portion 3d substantially fits may be formed, and pressure may be applied in a state where the upper surface tapered portion 3d of the valve seat 3 is substantially fitted into the concave portion 34 of the upper electrode 24. . That is, when the pressure is applied in this manner, the pressing force acts also in the diameter reducing direction of the valve seat 3, so that even if the temperature of the valve seat 3 rises, the expansion can be prevented, and the cylinder head body 2 Is large, the difference in the amount of shrinkage is small. Therefore, even in this case, generation of a vertical crack in the valve seat 3 can be prevented.

Further, as shown in FIG. 19, chamfered portions 3e, 3e are formed at corners of the inner peripheral surface, the upper surface, and the lower surface in order to reduce stress concentration on the inner peripheral surface of the valve seat 3. It is desirable.

Further, since the inner peripheral surface side of the valve seat 3 is a portion to be finally scraped off, only the portion to be shaved can be sintered as an inexpensive material.

In the above embodiment, the valve seat 3 as the metal member to be joined and the cylinder head body 2 as the base member are liquid-phase diffusion-bonded. It is not limited to phase diffusion bonding. That is, in solid-phase diffusion bonding in which the metal member to be bonded and the base member are bonded in a solid state, the above-described electric heating may be performed.

(Embodiment 2) FIG. 20 shows a main part of a joining apparatus 20 according to Embodiment 2 of the present invention (note that the same parts as those in FIG. 7 are not described in detail and only different parts are shown. It will be described later), and the energization path is different from that of the above embodiment.

That is, in this embodiment, the joining device 2
0 has a lower electrode 25 as in the above embodiment, but this lower electrode 25 is not connected to the welding power source 26 and is used only for pressurizing the valve seat 3 and the cylinder head body 2. Have been. Then, the upper electrode 24
Is composed of two first and second electrodes 24a and 24b, and the first electrode 24a is the same as in the above embodiment. On the other hand, the second electrode 24b can be vertically moved independently by another pressure cylinder similar to the pressure cylinder 22 for vertically moving the first electrode 24a. In addition, the second
The electrode 24b is made of carbon different from the first electrode 24a, and both electrodes 24a and 24b are connected to the welding power source 26, respectively.

The first and second electrodes 24a and 24b are
In the same cylinder head body 2, it comes into contact with the upper surfaces of the unjoined valve seat 3 newly joined and the joined valve seat 3 joined previously, respectively. When the welding power source 26 is turned on, the current flows through the first electrode 24a, the unjoined valve seat 3, the cylinder head body 2, the already-joined valve seat 3, and the second electrode 24b in order.
It returns to the welding power source 26. Thus, the already-joined valve seat 3 serves as a return-side energization path when the unjoined valve seat 3 is joined.

Therefore, in the second embodiment, when the unjoined valve seat 3 is joined, the resistance heating value is small on the already-joined valve seat 3 side and the internal temperature of the already-joined valve seat 3 is similar to that of the unjoined valve seat 3. However, since the second electrode 24b made of carbon self-heats, even if the already-sealed valve seat 3 is hardened and hardened as described in the basic embodiment 2, In addition, tempering can be performed appropriately. Moreover, the tempered valve seat 3 can be tempered without increasing the number of steps in-line. Therefore, it is possible to effectively suppress the thermal effect of increasing the hardness of the valve seat 3 at the time of joining.

In the second embodiment, the second electrode 24b
Is made of carbon. However, since this is a material having the largest self-heating value, if the temperature of the joined valve seat 3 becomes too high, the second electrode 24b is made of, for example, iron or brass, and tempering is effective. What can be done can be selected.

(Embodiment 3) FIG. 21 shows a piston 41 of a diesel engine as a joining metal member according to Embodiment 3 of the present invention. Piston body 42
A wear-resistant ring 43 (a non-bonded metal member) made of an Fe-based material is provided on the upper outer peripheral portion of the (base member), and Fe is provided on a wall surface inside a combustion chamber 42 a provided at an upper central portion of the piston body 42.
The heat shield members 44 (non-joined metal members) of the system are joined together.

That is, conventionally, the piston body 42 is cast by casting the wear ring 43, but the piston body 4
2 is T6 heat treated to improve its strength,
Since the brittle intermetallic compound of Fe-Al is generated when the wear ring 43 is cast, it is impossible to perform the T6 heat treatment. However, in this embodiment, the piston main body 42 is subjected to T6 heat treatment in advance, and the piston main body 42 is subjected to T6 heat treatment.
Can be joined to the wear ring 43. Even if the wear ring 43 is joined to the piston main body 42 and then subjected to T6 heat treatment, the heat resistance is good and Fe-Al is hardly generated, so there is no problem. Therefore, both the wear resistance and the strength of the piston 41 can be improved.

On the other hand, the wall of the piston body 42 inside the combustion chamber 42a has a problem that cracks are likely to occur particularly at corners. However, in this embodiment, since the reinforcing member 44, for example, austenitic stainless steel, is joined to the lip portion in the combustion chamber 42a, it is possible to prevent the occurrence of cracks in the wall portion in the combustion chamber 42a. it can.

(Embodiment 4) FIG. 22 shows a main part of an engine cylinder block 51 as a joining metal member according to Embodiment 4 of the present invention.
Is formed on the water jacket 52a of the cylinder block body 52 (base member) made of an Al-based material.
A rib member 53 (non-joined metal member) made of a system material is joined. Reference numeral 54 denotes a cast iron liner fitted to the inner peripheral surface of the cylinder.

That is, conventionally, the cylinder block 51
In order to improve the rigidity of the cylinder block 52, a rib is integrally formed on the upper portion of the water jacket portion using a sand core at the time of casting of the cylinder block body 52. However, this method requires a long cycle time at the time of casting. And there is a problem that productivity is poor. However, in this embodiment, the rib member 5 is formed while facilitating the casting of the cylinder block body 52.
3 can be joined to the upper part of the water jacket 52a of the cylinder block main body 52 in a short time, and the rigidity of the cylinder block can be improved. For this reason,
The deformation of the liner 54 on the inner peripheral surface of the cylinder can be prevented, and the performance of the engine such as LOC and NVH can be improved. Also, it can be made linerless.

[0107]

Next, a specific embodiment will be described. First, as a base member, as shown in FIG.
The test piece 61 was cast from an Al alloy casting (AC4D specified in JIS H5202). Then, the test piece 61 was subjected to a T6 heat treatment.

Subsequently, as shown in Table 1, the brazing material coating method, the sheet shape, and the taper angle θ of the first joint surface portion
1 were made different to produce five types of Fe-based valve seats (Examples 1 to 5).

In Table 1, “Friction” in the column of brazing material coating method is a method of coating by rubbing the brazing material when forming a diffusion bonding layer and a brazing material layer on the surface of the valve seat. That is. On the other hand, “ultrasonic waves” refers to a method of coating a brazing material by ultrasonic plating, as described in the first embodiment. Further, "thin" in the column of the seat shape means that the valve seat has a shape close to the final shape and is thin, as shown in FIG.
On the other hand, “thick” means that the wall has a large thickness in the same shape as the above embodiment, as shown in FIG.

The material of the valve seat used was one having the components shown in Table 2. In Table 2, the numerical values are% by weight.
And TC is the total carbon amount (total amount of free carbon (graphite) and carbon of cementite).

Further, the brazing filler metal contains 95% by weight of Zn component, 4.95% by weight of Al component and 0.05% by weight of M
What consisted of a g component was used.

Further, the interior of each valve seat was infiltrated with a Cu-based material, and the surface was plated with Cu.

Each of the valve seats of Examples 1 to 5 was joined to the test piece 61 by a joining apparatus in the same manner as in the first embodiment. The pressure and current value at the time of this joining were set to the values shown in Table 1. In addition, about a current value,
Since the contact resistance between the valve seat and the test piece 61 changes due to a change in the applied pressure and the like, the embedment depth of the valve seat changes, so that the embedment depth is set to be substantially the same.

For comparison, a thick-walled shape and θ1
= 0.52 rad (30 °) valve seat (C on the surface
u-plated), the applied pressure and the current value were 2
Solid-phase diffusion bonding (pressure welding) was performed at 9420N (3000 kgf) and 70 kA (comparative example).

Next, the joint strength of the valve seats of Examples 1 to 5 and Comparative Example was measured. That is, as shown in FIG. 26, the test piece 61 is placed on the upper surface of the jig base 63 so that the side where the valve seat 62 is joined is on the lower side. To prevent this, the jig table 63 is positioned above a through hole 63a provided substantially at the center of the jig table 63. Then, a cylindrical pressing jig 64 is inserted from above the through hole 61 a of the test piece 61 to push the valve seat 62, and a pulling load when the valve seat 62 comes off from the test piece 61 is measured. This removal load corresponds to the joining strength.

FIG. 27 shows the results of the above-mentioned pulling load measurement test. As a result, by comparing Example 1 and Example 2, the case where the diffusion bonding layer and the brazing material layer are formed on the surface portion of the valve seat by ultrasonic plating is performed by rubbing the brazing material. It can be seen that the bonding strength is improved as compared with the method. This is because the diffusion bonding layer remained on the surface of the valve seat after the test in Example 2 as described later (see FIG. 30), whereas in Example 1, the brazing material layer and the diffusion bonding layer Since almost no trace was observed, it can be estimated that in Example 1, the diffusion bonding layer was not completely formed.

Here, a micrograph (approximately 180 times magnification) of the surface of the valve seat immediately after the ultrasonic plating in Example 2 is shown in FIG. 28, and the joint surface between the valve seat and the test piece 61 after bonding is shown in FIG. Micrograph (approximately 3 magnification)
FIG. 29 shows a microphotograph (approximately 360 times) of the surface of the valve seat after the pulling load measurement test.
0 is shown. In FIG. 28, the upper side is a valve seat, and the lower side is formed with a brazing material layer via a thin diffusion bonding layer instead of a Cu plating layer. In addition, it turns out that the hole which infiltrated the Cu-based material exists inside the valve seat. In FIG. 29, there is no gap between the upper valve seat and the lower test piece 61, and the diffusion bonding layer and the molten reaction layer are clearly present. Further, in FIG. 30, it can be seen that a thin diffusion bonding layer remains on the surface portion (lower surface portion) of the valve seat.

Further, by comparing Example 2 and Example 3, it can be seen that a thicker valve seat has a larger pulling load than a thin valve seat. This is similar to Example 2
Can be presumed to be due to the fact that the actual pressing force acting on the joint surface has decreased due to the deformation since the corners and the like of the valve seat are deformed.

By comparing the third embodiment with the fourth embodiment, the fourth embodiment in which the taper angle θ1 of the first joint surface portion is larger has the oxide film destruction effect as described in the first embodiment. It can be seen that the effect is excellent and the bonding strength increases.

Further, when comparing Example 4 and Example 5, it is found that Example 5 having a larger pressing force has higher bonding strength. Moreover, the pressing force is 29420N (3000
It can be seen that by setting to kgf), the joining strength is significantly improved as compared with the comparative example.

Here, FIG. 31 shows an electron microscope photograph (approximately 10,000 times magnification) of the joint surface of the valve seat and the test piece 61 after the joining in Example 5 described above. In this figure, the left side is a valve seat (including a portion that looks white), and the right side is a test piece 61. The gray portions between them are the diffusion bonding layer and the molten reaction layer. It can be seen that the thickness of both layers is about 1 μm. still,
When the elements in both layers were analyzed, Fe, Zn and Al were respectively detected.

In order to investigate the influence of the pressing force in more detail, the pressing force was set to 9807 N (1000 kgf) while the brazing material coating method, the sheet shape, and the taper angle θ1 of the first joint surface were the same as those in the above-described Embodiments 4 and 5. , 147
10N (1500kgf) and 29420N (3000
kgf) and set the valve seat to the test piece 61.
And the extraction load was measured in the same manner as in the initial extraction load measurement test.

When the pressing force is 9807 N (1000 kg
The hardness of the test piece 61 after bonding was measured for the test piece f) and that for 29420N (3000 kgf). The measurement of the hardness is based on the fact that the valve seat is moved from the corner between the first joint surface and the second joint surface of the valve seat (point = 0 from the joint surface in FIG. 33) toward the outer peripheral side of the test piece 61. This was performed at predetermined intervals along a direction inclined by about 0.79 rad (45 °) to the side opposite to the joined side.

FIG. 32 shows the results of the above-mentioned pulling load measurement test.
FIG. 33 shows the results of the hardness measurement test. From this, it can be seen that the higher the pressing force, the higher the bonding strength, and the higher the pressing force, the higher the hardness of the test piece 61 near the bonding surface. This is because the higher the applied pressure, the lower the contact resistance and the smaller the calorific value, so that the softening of the test piece 61 is suppressed. When the softening is suppressed, the plastic flow is reliably performed and the oxide film is formed. This is because the effect of the destruction of the brazing material increases and the brazing material is reliably discharged.

Next, in order to examine the effect of the pulse current, the valve seat was joined to the test piece 61 by performing the pulse current. The large current value and the small current value of this pulse conduction were set to 70 kA and 0, respectively. The energizing time of the large current value pulse was 0.5 seconds, and the energizing time of the small current value pulse was 0.1 seconds. Furthermore, the pulse number of the large current value is 6
Pulsed. On the other hand, for comparison, continuous energization (60 k
The valve seat was joined to the test piece 61 by applying a current of A for 2 seconds). The pressure was 29420N for both
(3000 kgf).

[0126] For those joined by pulse current application and continuous current application, the hardness before and after bonding at the upper and lower ends (A) and the center in the vertical direction (B) of the valve seat, the test piece 61, respectively. A predetermined distance along a direction inclined from the corner between the first joint surface and the second joint surface of the valve seat toward the outer peripheral side of the test piece 61 by about 45 ° to the side opposite to the side where the valve seat is joined. The hardness and punching load were measured for each.

FIG. 34 shows the results of the hardness measurement test before and after the joining. As a result, in the case of joining by continuous energization, the hardness in the vertical center (part B) becomes particularly high after joining, whereas in the case of joining by pulse energization, burning does not occur due to slow cooling. It can be seen that the hardness hardly increased.

FIG. 35 shows the results of a hardness measurement test based on the distance from the joint surface. As a result, it can be seen that the hardness of the test piece 61 is reduced by receiving heat from the valve seat in the case of joining by pulsed electric current.

FIG. 36 shows the results of measurement of the pulling load. From the above, it is possible to reduce the temperature difference between the valve seat and the test piece 61 by radiating the heat to the test piece 61 while suppressing the increase in hardness by performing the slow cooling inside the valve seat by the pulse current, and reducing the shrinkage amount. Can be reduced, and the bonding strength can be improved.

Subsequently, in order to examine how the valve seat is embedded in the test piece 61 in the pulse current application, the embedded amount y is determined according to the time from the start of pressurization.
(See FIG. 37). At this time, the large current value of the pulse current was set to 68 kA, and the small current value was set to 0. Also, the energizing time (H) of the large current value pulse, the energizing time (C) of the small current value pulse, and the number of large current value pulses (N) are variable, and are 0.5 seconds and 0.1 seconds, respectively, under basic conditions. And 6 pulses. Then, a test was performed by changing only one of these basic conditions (see FIG. 38 for the changed conditions).

FIG. 38 shows the results of the embedding amount measurement test. From this, it can be seen that the embedding was almost completed by the first energization of the large current value pulse, and the embedding did not progress in the energization performed later. In addition, the embedding amount hardly changes within the range of the setting conditions of this test. However, when the energizing time of the large current value pulse is as long as 1 second, the embedding amount is slightly larger than at the time of energizing the first large current value pulse than in other cases, and when the number of pulses is as large as 9 pulses, It can be seen that the test piece 61 softens from the middle and the embedding proceeds. Therefore, the condition that the valve seat can be embedded in the first energization of the large current value pulse, and the condition that the slow cooling inside the valve seat and the heat radiation to the cylinder head body can be performed in the energization of the second and subsequent large current value pulses, respectively. Just set it.

Finally, the valve seat is made of a sintered forged material,
This was joined to the test piece 61 by applying a pulse current at a pressing force of 29420 N (3000 kgf). At this time, the large current value of the pulse current was set to 60 kA, and the small current value was set to 0.
Also, the energizing time of the large current value pulse, the energizing time of the small current value pulse, and the number of the large current value pulse are each 0.5 seconds,
0.1 seconds and 4 pulses. In addition, for comparison, Cu
A valve seat made of a sintered material infiltrated with a system material was similarly joined to the test piece 61. However, the large current value of the pulse current was 53 kA. The outer circumference of the test piece 61 is determined from the corner between the first joint surface and the second joint surface of the valve seat in the test piece 61 for the case where the valve seat is a sintered forged material and the case where the valve sheet is a sintered material infiltrated. About 0.79 rad (45 °) on the side opposite to the side where the valve seat is joined toward the side
The hardness was measured at a predetermined distance along the inclined direction.

FIG. 39 shows the result. From this,
It can be seen that the infiltrated sintered material has lower hardness inside the test piece 61. This is because the heat generation inside the valve seat was suppressed by the infiltration of the Cu-based material and the heat generation was effectively performed at the joint surface portion, so that the test piece 61 was softened. However, even if the valve seat is a sintered forged material, the joining is performed well. This can be seen from the micrograph of the joint surface between the sheet and the test piece 61 (approximately 50 times magnification in FIG. 40, FIG.
It can be seen from the magnification of about 400 for 1). This is because the holes inside the valve seat are crushed by forging and have the same effect as infiltration.

[0134]

As described above, claim 1 or claim 1
According to the invention described in Item 3, since the energization heating is performed with the slow cooling current value smaller than the initial current value after the energization heating using the initial current value, the temperature difference between the two members is reduced. Therefore, it is possible to suppress the occurrence of thermal stress due to the difference in the coefficient of thermal expansion between the two members after the completion of the energization heating, and to prevent the occurrence of cracks.

According to the second or fourteenth aspect of the present invention, since the first metal member is energized and heated by the initial current value until the first metal member is displaced to the predetermined joining position, it is gradually cooled while the joining is in an insufficient state. It is possible to avoid a situation in which energization heating by a current value is performed, and it is possible to securely join the first metal member and the second metal member.

According to the third or fifteenth aspect of the present invention, it is possible to easily set a predetermined time for conducting and heating with an initial current value. Therefore, the switching from the initial current value to the slow cooling current value can be smoothly performed, and the energized heating can be easily and reliably performed.

According to the fourth or 16th aspect of the present invention, diffusion bonding can be performed such that the first metal member is buried in the second metal member by current heating at the initial current value. The heating with the current at the initial current value is performed until the first metal member is embedded in the predetermined joining position, so that both members can be joined reliably. Further, after the first metal member is embedded in the predetermined joining position, the electric heating is performed at the gradual cooling current value. Therefore, while the first metal member is maintained at the appropriate position, the gradual cooling of both members is performed. It can be carried out. Therefore, highly accurate bonding can be performed.

According to the fifth or 17th aspect of the present invention, the energization heating based on the initial current value can be used for embedding the first metal member in the second metal member, while the slow cooling current Electric heating by value can be used for slow cooling of both members. Electric heating by slow cooling current value
Since the embedding of the first metal member is suppressed, the first
A situation in which the metal member is excessively embedded in the second metal member can be reliably prevented. Therefore, the temperature difference between the two members can be reduced while maintaining the positions of the two members appropriately, and the occurrence of cracks can be prevented.

According to the sixth aspect of the present invention, the thermal stress of the first metal member, which tends to expand and contract in the radial direction, can be alleviated by the energization heating using the slow cooling current value. Vertical cracks can be prevented. Therefore,
The effects of the inventions of claims 1 to 5 can be remarkably exhibited.

According to the seventh aspect of the present invention, cracks due to differences in the coefficient of thermal expansion do not occur, and
A metal member made of an e-based material and an Al-based material can be obtained, and the effects of the inventions of claims 1 to 6 can be remarkably exhibited.

According to the invention described in claim 8 or 18, a metal member having high joining strength and heat resistance higher than that of the brazing material used can be obtained by in-line operation.

According to the ninth aspect of the present invention, the eighth aspect is provided.
As a joining method according to the invention, the combination of materials can be optimized.

According to the tenth aspect of the present invention, the oxide film and the plating layer on the surface of the first metal member are destroyed by the cavitation action by the ultrasonic wave. The brazing material can be more reliably diffused to the first metal member side than the method using the mechanical friction of rubbing against the portion. Therefore, the diffusion layer can be reliably formed by a simple method, and a bonding metal member having higher bonding strength can be obtained.

According to the eleventh aspect of the present invention, since the high electrical conductivity material infiltrates into the pores inside the first metal member, the same effect as forging can be obtained, and the first metal member is energized during energization.
The heat generated inside the metal member can be suppressed, and the brazing material can be effectively melted. Therefore, the joining strength of the joining metal member can be effectively improved.

According to the twelfth or nineteenth aspect, the oxide film on the surface of the second metal member is effectively destroyed and discharged from the joint surface, so that the brazing material is moved to the second metal member side. The diffusion can be ensured, and there is no need to particularly protect the surface of the second metal member. On the other hand, the second
The plastic flow of the metal member can be easily performed by utilizing the pressing force when pressing the first metal member and the second metal member, and no special means is required. Therefore, the diffusion layer can be reliably formed by a simple method,
The joining strength of the joining metal member can be further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a main part of an engine cylinder head as a joining metal member according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically illustrating a joined state of a valve seat and a cylinder head main body.

FIG. 3 is a sectional view showing a shape of a valve seat before joining.

FIG. 4 is an explanatory view showing a procedure for joining a valve seat to a cylinder head body.

FIG. 5 is an explanatory view schematically showing a joining process of a valve seat and a cylinder head main body.

FIG. 6 is an explanatory diagram showing a state in which a brazing material is coated by applying ultrasonic vibration to a surface portion of a valve seat in a brazing material bath.

FIG. 7 is a side view showing the joining device.

8 (a) is a view in the direction of arrow VIII in FIG. 7, and FIG. 8 (b)
FIG. 4 is a plan view of the lower surface of the upper electrode.

FIG. 9 is a timing chart showing a control method of pressurization and energization.

FIG. 10 is a diagram corresponding to FIG. 9 showing another example of the pressurization control method.

FIG. 11 is a phase diagram of an Al—Zn alloy.

FIG. 12 is a diagram corresponding to FIG. 9, showing a basic mode 2.

FIG. 13 is a graph showing a temperature change inside a valve seat due to pulsed current.

FIG. 14 is a diagram corresponding to FIG. 9 showing another example of the energization control method.

FIG. 15 is a cross-sectional view showing a state in which cooling water is sprayed on the inner peripheral surface of the valve seat.

FIG. 16 is a diagram corresponding to FIG. 9 showing the first embodiment.

FIG. 17 is a diagram corresponding to FIG. 9, illustrating another example of the energization control method.

FIG. 18 is a cross-sectional view showing a state in which the valve seat is also pressed in the diameter reducing direction to suppress the thermal expansion thereof.

FIG. 19 is a view corresponding to FIG. 3, showing another example of the shape of the valve seat.

FIG. 20 is a cross-sectional view of a main part showing a state where the valve seat and the cylinder head main body are joined by the joining device according to the second embodiment.

FIG. 21 is a cross-sectional view illustrating an engine piston as a bonded metal member according to the third embodiment.

FIG. 22 is a sectional view showing a main part of a cylinder block of an engine as a joining metal member according to a fourth embodiment.

FIG. 23 is a sectional view showing a test piece.

FIG. 24 is a sectional view showing a thin valve seat.

FIG. 25 is a cross-sectional view showing a thick valve seat.

FIG. 26 is a schematic cross-sectional view showing a procedure of a pulling load measurement test.

FIG. 27 is a graph showing the results of a punching load measurement test on the valve seats of Examples 1 to 5 and Comparative Example.

FIG. 28 is a micrograph showing a state of a valve seat surface immediately after ultrasonic plating.

FIG. 29 is a photomicrograph showing a joint state between a valve seat and a test piece in Example 2.

FIG. 30 is a photomicrograph showing the state of the valve seat surface after the pulling load measurement test.

FIG. 31 is a photomicrograph showing a joint state between a valve seat and a test piece in Example 5.

FIG. 32 is a graph showing the relationship between the welding pressure and the unloading load.

FIG. 33 is a graph showing a change in hardness depending on a distance of a test piece from a bonding surface portion.

FIG. 34 is a graph showing changes in hardness before and after joining of a valve seat in continuous energization and pulse energization.

FIG. 35 is a graph showing a change in hardness depending on a distance from a joint surface of a test piece in continuous energization and pulse energization.

FIG. 36 is a graph showing the results of an extraction load measurement test in continuous energization and pulse energization.

FIG. 37 is an explanatory diagram showing an embedding amount y in an embedding amount measurement test.

FIG. 38 is a graph showing the relationship between the time from the start of pressurization and the embedding amount y.

FIG. 39 is a graph showing a change in hardness according to a distance from a joint surface portion of a test piece in a case where a valve seat is a sintered forged material and in a case where a valve material is an infiltrated sintered material.

FIG. 40 is a micrograph showing a joint state between a valve seat made of a sintered forged material and a test piece.

FIG. 41 is a micrograph showing a further enlarged view of a joint state between a valve seat made of a sintered forged material and a test piece.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Cylinder head main body (2nd metal member) 2a Joining surface 2b Port 3 Valve seat (1st metal member) 3a 1st joining surface 3b 2nd joining surface 5 Diffusion joining layer 6 Melting reaction layer 7 Brazing material Layer 14 brazing material bath

[Table 1]

[Table 2]

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B23K 20/00 310 B23K 20/00 310A 310M 20/10 20/10 35/28 310 35/28 310D F01L 3/22 F01L 3/22 B F02F 1/24 F02F 1/24 S H05B 3/00 310 H05B 3/00 310B // B23K 103: 20 (72) Inventor Yukihiro Sugimoto 3-1, Fuchu-cho, Shinchu, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Invention Nobuya Shibata 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (19)

[Claims] 1. A method for joining metal members by diffusion joining a first metal member to a second metal member having a different coefficient of thermal expansion from the first metal member, wherein the first metal member is connected to the first metal member by the first metal member. The two members are heated at a predetermined initial current value for a predetermined time while being pressed while being in contact with the joining surface of the metal member of No. 2, and thereafter, the two members are cooled at a slow cooling current value smaller than the initial current value. A method for joining metal members, wherein the members are electrically heated. 2. The method for joining metal members according to claim 1, wherein the predetermined time for energizing and heating at the initial current value is from the start of energizing heating until the first metal member is displaced to a predetermined joining position. A method for joining metal members, characterized in that: 3. The method for joining metal members according to claim 1, wherein the predetermined time for energizing and heating at the initial current value is set to a predetermined certain time after starting the energizing heating. Joining method. 4. The method for joining metal members according to claim 1, wherein the first metal member is pressurized and energized to heat the first metal member to form a second metal member. A predetermined time for energizing and heating at the initial current value is embedded in the bonding surface portion of the metal member until the first metal member is embedded at a predetermined bonding position with respect to the second metal member after starting the energizing heating. A method for joining metal members, characterized in that: 5. The method for joining metal members according to claim 4, wherein the initial current value is set to a current value at which embedding of the first metal member into the second metal member proceeds. The method of joining metal members, wherein the slow cooling current value is set to a current value that suppresses the embedding of the first metal member into the second metal member. 6. The method for joining metal members according to claim 1, wherein the first metal member is a ring-shaped member, and the second metal member is a ring-shaped member. A joining method of a metal member, wherein a joining surface surrounding an outer peripheral portion is formed. 7. The method for joining metal members according to claim 1, wherein the first metal member is made of an Fe-based material, and the second metal member is made of an Al-based material. A method for joining metal members, comprising: 8. The method for joining metal members according to claim 1, wherein a brazing material having a lower melting point than both metal members is formed on a surface portion of the first metal member in advance. A brazing material layer is formed via a diffusion layer with the first metal member, and the first metal member and the second metal member are brazed by heat generation and pressure accompanying energization between the two members. Forming a diffusion layer of the material and the second metal member and joining the molten brazing material in a liquid phase diffusion state through the two diffusion layers while discharging the molten brazing material from between the joining surfaces of the two members. How to join members. 9. The method according to claim 8, wherein the first metal member is made of an Fe-based material, the second metal member is made of an Al-based material, and the brazing material is a Zn-based material. A method for joining metal members, comprising a material. 10. The bonding method of a metal member according to claim 8, wherein the diffusion layer of the first metal member and the brazing material has an ultrasonic wave on a surface portion of the first metal member. A method for joining metal members, wherein the metal member is formed by coating a brazing material by applying vibration. 11. The method according to claim 1, wherein the first metal member is brought into contact with the second metal member before the first metal member is brought into contact with the second metal member. A method for joining metal members, comprising infiltrating a high electrical conductivity material into the inside of the metal member. 12. The method for bonding metal members according to claim 1, wherein the diffusion bonding between the first metal member and the second metal member is performed by a second bonding method.
The method of joining metal members, wherein the joining surface of the metal member is plastically flowed. 13. A joining apparatus for a metal member for diffusion joining a first metal member to a second metal member having a different coefficient of thermal expansion from the first metal member, wherein the first metal member is connected to the first metal member by the first metal member. Pressurizing means for bringing the two metal members into contact with each other and pressing the two members so that pressure is applied to the two metal members; and passing through the bonding surface from one of the two members toward the other. An electrode for flowing current flowing therethrough; welding power supply means for supplying a current between the electrodes when the two members are pressurized by the pressurizing means; Switching means for switching to a slow cooling current value smaller than the current value. 14. The metal member joining apparatus according to claim 13, wherein the switching means switches the initial current value to the slow cooling current value when the first metal member is displaced to a predetermined joining position. An apparatus for joining metal members, wherein the apparatus is set. 15. The metal member joining apparatus according to claim 13, wherein the switching means is configured to switch the initial current value to the gradual cooling current value when a predetermined time has elapsed from the start of energization. A joining device for a metal member. 16. The welding apparatus for a metal member according to claim 13, wherein the welding power supply means energizes and heats the first metal member while being pressed by the pressing means. The first metal member is embedded in the joint surface of the second metal member, and the switching means includes position detection means for detecting the embedded position of the metal member to be joined, Is set so as to switch the initial current value to the slow cooling current value when it is detected that is embedded in a predetermined embedding position. 17. The metal member joining apparatus according to claim 16, wherein the initial current value is set to a current value that allows the first metal member to be embedded in the second metal member. The apparatus for joining metal members, wherein the slow cooling current value is set to a current value that suppresses the embedding of the first metal member into the second metal member. 18. The joining apparatus for a metal member according to claim 13, wherein the welding power supply means comprises a first metal member on which a diffusion layer and a brazing material layer are formed in advance. By applying current and heating to the joining surface of the metal member while being pressed by the pressing means, a diffusion layer between the brazing material and the second metal member is formed, and the molten brazing material is removed from between the joining surfaces of the two members. An apparatus for joining metal members, wherein the two members are joined in a liquid phase diffusion state via the two diffusion layers while discharging. 19. The joining apparatus for a metal member according to claim 13, wherein the welding power source is in contact with the joining surface of the first metal member and the second metal member. The metal member is characterized in that the heating is carried out in a state where the two metal members are pressurized by a pressurizing means so that the joining surface portion of the second metal member plastically flows while the two members are diffusion-bonded. Joining equipment.