JP2001192891A - Aluminum alloy component and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide an aluminum alloy component capable of improving wear resistance, surface hardness, and component strength, and a method of manufacturing the same. SOLUTION: An alumite film 10 formed on the surface of a base material of an aluminum alloy component used for a sliding portion contains copper,
Alternatively, any one of zinc is contained in 0.5% or more, or both are contained in 0.5% or more in total, and at least one of the copper or zinc particles 10c contained on the surface of the alumite film 10 is contained. Exposed aluminum alloy parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy component and a method for producing the same, and more particularly to a component for forming an alumite film (anodized film) on the surface of the component, or an anodized film. The present invention relates to the improvement of the components of the electrolytic solution, and the steps accompanying the anodizing step. In addition, content% in this specification means weight%.

[0002]

2. Description of the Related Art It has been known that an alumite film is formed on the surface of an aluminum alloy part by anodizing treatment in order to enhance the corrosion resistance, wear resistance, surface hardness and the like of the part. This anodizing treatment is performed by immersing an aluminum alloy part in an electrolytic solution and connecting the part to the anode side by an electrolytic action.

[0003] Conventionally, the above-mentioned aluminum alloy parts have been described in Table 1.
A3003, A6061, AC3A, AC4A,
Cutting / polishing molding using extruded aluminum alloy such as AC4C, AC4CH, press molding using wrought aluminum alloy, casting such as die casting, sand casting or die casting using these aluminum alloys It is formed by molding, forging, cutting, polishing, pressing and forging after powdering and then compacting, or a combination of press forming, casting, forging, cutting and polishing.

[0004]

However, even if an aluminum alloy part made of the above-mentioned material is formed with an alumite film in order to increase the surface hardness, the aluminum alloy part can be used as a base material in an electrolyte made of sulfuric acid in the alumite treatment. Of the slightly contained copper and zinc, those exposed on the surface of the alumite film are eluted, and the surface of the alumite film is slightly porous due to traces of elution, and there is a problem that sufficient surface hardness cannot be obtained. For this reason, the sliding part that slides relatively to the mating part is easily worn regardless of whether or not lubricating oil is used, and when the lubricating oil is not used, the mating part easily adheres to the alumite film surface, There was a problem that not only the alumite film but also the mating parts were worn. Therefore, conventionally, in the aluminum alloy parts made of A3003, A6061, AC3A and the like, since the content of copper and zinc may be large within the specified value range, the alumite treatment is performed on the sliding portion. Did not. In addition, since heat treatment does not provide sufficient strength for aluminum alloy parts containing only a small amount of copper or zinc, heat treatment has not been performed. Further, there is a problem that sufficient strength cannot be obtained regardless of the presence or absence of heat treatment.

The present invention has been made in view of the above-mentioned conventional problems, and provides an aluminum alloy part capable of improving the wear resistance and surface hardness of a sliding part and the strength of the part, and a method of manufacturing the same. Is an issue.

[0006]

According to the first aspect of the present invention, one of copper and zinc is contained in an alumite film formed on the surface of a base material of an aluminum alloy component used for a sliding portion.
0.5% or more, or both of them in a total of 0.5% or more, and at least one of the contained copper and zinc particles is exposed on the surface of the alumite film. Aluminum alloy parts.

According to a second aspect of the present invention, in the first aspect, the base material of the aluminum alloy component is any one of copper and zinc.
0.7 to 7%, or a total of 0.7 to 10
% Aluminum alloy.

According to a third aspect of the present invention, there is provided a method of manufacturing an aluminum alloy part in which an alumite film is formed on the base material surface of the aluminum alloy part by anodizing treatment through an electrolytic solution. An aluminum alloy containing 0.7 to 7% of any one of zinc or 0.7 to 10% of both is used, and the electrolyte contains sulfuric acid, and further contains oxalic acid or It is characterized by containing any one of a mixture of oxalic acid and citric acid.

A fourth aspect of the present invention is characterized in that, in the third aspect, a solution treatment and an age hardening treatment are performed before or after the anodizing step of forming an alumite film via the electrolytic solution.

According to a fifth aspect of the present invention, in the third aspect, a solution treatment is performed before the anodizing step of forming an alumite film via the electrolytic solution, and an age hardening treatment is performed after the anodizing step. It is characterized by:

[0011]

According to the first aspect of the present invention, both copper and zinc are dispersed in the alumite film, and some of the particles are exposed on the surface of the film. When the component of the present invention is used for a sliding portion that slides relatively with a mating component, and when a lubricating oil for reducing wear is used, the exposed copper or zinc particles Since the lubricating oil is easily adsorbed, it is difficult for oil to run out in the sliding portion, and even when no lubricating oil is used, some of the copper or zinc particles that are exposed diffuse to the surface of the alumite film and perform a lubricating action. This can prevent the problem that the mating part is worn and that the alumite film adheres to the mating part and wears as a result.

According to the second aspect of the present invention, since both copper and zinc in the base material are dispersed and dissolved in the aluminum alloy of the base material, dislocations generated in the aluminum crystal when an external force acts. Is prevented by the copper or zinc, so that the strength of the component can be improved.

According to the third aspect of the present invention, an alumite film is formed on the base material containing either copper or zinc by anodizing treatment through an electrolytic solution in which these are hardly eluted. Copper and zinc are easily dispersed in the alumite film, and copper and zinc particles are exposed on the surface of the alumite film in a dispersed state. Thereby, the wear resistance of the sliding portion can be more reliably improved.

According to the fourth and fifth aspects of the present invention, the strength of the alumite alloy component can be improved by the solution treatment and the age hardening treatment, and the solution treatment or the age hardening treatment after the anodic oxidation step can improve the strength. Cracks can be generated in the alumite film, and the lubricating oil impregnating function by the cracks enhances lubricity, and as a result, abrasion resistance can be improved.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 to 16 are views for explaining a cylinder block and a piston (aluminum alloy part) of an internal combustion engine and a method of manufacturing the same according to a first embodiment of the present invention.

In the figure, a four-cycle internal combustion engine 101
Is a cylinder head 102 formed by low pressure casting or die casting of an aluminum alloy, and a cylinder block 103.
And the crankcase 104. An intake pipe 105 is connected to one side of the cylinder head 102, and an intake valve 10 is provided at an intake opening 105a at a downstream end thereof.
6 is mounted. An exhaust pipe 7 is connected to the other side of the cylinder head 102, and an exhaust opening 107a at an upstream end thereof is provided.
The exhaust valve 108 is mounted on the hopper. The piston 109 slides along the inner surface of the cylinder bore of the cylindrical cylinder block 103. Piston ring 11 is provided on the peripheral surface of piston 109.
0 is attached. The piston 110 includes a piston pin 111, a connecting rod 112, and a crank arm 113.
Through a crankshaft 114.

The inner surface of the cylinder bore of the cylinder block 103, which is the sliding surface of the piston 109, that is, the cylindrical inner surface, is of a type in which a sleeve 117 made of an aluminum alloy is mounted by press-fitting or casting. There is a sleeveless type that comes into contact with the cylindrical inner surface of the cylinder block 103. In this embodiment, the alumite treatment is applied to the inner cylindrical surface to improve the wear resistance of the sliding surface of the piston 109 in any of the types.

FIG. 2 is a configuration diagram of the alumite processing apparatus according to the embodiment of the present invention. In the present embodiment, the alumite processing device performs alumite processing on the inner surface of the sleeve 117 that is the sliding surface of the piston mounted on the cylinder block 103. The cylinder block 103 is mounted on a support base 116 via a gasket 115. The gasket 115 is a sealing material for preventing leakage of the electrolytic solution and functions as an insulating material for allowing more electrolytic current to flow from the cylinder bore surface. An electrode rod 129 is inserted into the sleeve 117 in the axial direction. The electrode rod 129 is connected to the rectifier 124 from the AC power supply 130.
And DC power supply 1 converted to DC through control circuit 125
31 is connected to the negative electrode side. The positive electrode side of DC power supply 131 is connected to cylinder block 103 on which sleeve 117 is mounted. As a result, an anodic oxidation reaction occurs between the negative electrode rod 129 and the inner surface of the positive electrode side sleeve 117 opposed to the electrode rod 129 at an interval via the electrolytic solution. An alumite layer which is an anodized film is formed.

The upper end of the sleeve 117 is sealed with a cover 119 via an O-ring 118. An electrolyte circulation channel 120 is connected to the cover 119 and communicates therewith. The lower end (not shown) of the support base 116 is also sealed, and the electrolyte 127 in the electrolyte tank 126 is fed into the support base 116 by the circulation pump 128. Electrolyte is sleeve 11
7 and circulates in the circulation channel 120 by flowing between the electrode rod 129. In the middle of the circulation channel 120, the electrolyte layer 12
6, and a circulation pump 128 is provided.

On the circulation channel 120, a cooling device 132 is further provided. That is, the electrolytic solution tank 126, the circulating pump 128, the conduit between the electrolytic solution tank 126 and the circulating pump 128, the current passing portion for alumite treatment between the sleeve 117 and the electrode rod 129, and the circulation A pipe between the pump 128 and the current passage for alumite treatment, and the current passage for alumite treatment and the electrolyte bath 126
A cooling device 132 is arranged in series or in parallel in the flow direction of the processing liquid in any part of the pipeline between the cooling devices 132. The cooling device 132 may be, for example, a heat exchanger including a cooling coil 123 that forms an evaporator of a refrigerator to which the refrigerant pipe 122 is connected. Or cooling coil 1
Cooling water may be circulated through 23. Further, for example, a cooling fin is attached to a pipeline in the middle of the circulation channel 120, and an air-cooling type cooling device that cools with a fan is provided. After passing through the cooling device, it may join the circulation channel 120.

For example, a cooling coil through which cooling water passes is immersed in an electrolyte bath 126 or a circulation pump 128
The cooling device 132 may be configured such that a water jacket for cooling water circulation is provided therein, or a water jacket for cooling water circulation is provided inside the electrode rod 129.
Furthermore, cooling water may be circulated to the water jacket 103A around the cylinder bore of the cylinder block 103.

A temperature sensor 121 is mounted near the outlet of the sleeve 117 in the circulation channel 120 to detect the temperature of the electrolyte. The temperature sensor 121 is connected to, for example, a control device (not shown), and drives the cooling device 132 when the detected temperature rises above a set temperature, or a refrigerant (cooling water) thereof.
Feedback control is performed so that the flow rate is increased and the temperature rise of the electrolytic solution is suppressed to maintain a constant temperature. Along with the temperature control by the cooling device 132, the drive of the circulation pump 128 is controlled,
When the temperature rises, the circulation flow rate of the electrolytic solution may be increased to prevent a decrease in the reaction rate due to the temperature rise due to heat generation in the anodic oxidation reaction. Further, the DC power supply 131 may be controlled to increase the voltage when the temperature rises, thereby increasing the reaction speed.

The cover 1 on the outlet side of the sleeve 117
19, the upper side of the sleeve 117 is completely sealed.
A circulation passage may be formed at the center of the fuel cell 29 and the electrolyte may be returned to the electrolyte tank 126 through the circulation passage. In this case, the cooling device 132 can be provided on the pipe on the suction side or the discharge side of the circulation pump 128 to cool the electrolytic solution.

FIG. 3 is a flowchart showing the steps of manufacturing a sleeveless cylinder block. First, a cylinder block is formed by die casting of an aluminum alloy (step S1). As the material of the cylinder block, any one of ADC10 to ADC14 of the materials shown in Table 2 is used.

In order to increase the wear resistance, a metal carbide such as SiC or another intermetallic compound may be mixed in addition to the components shown in the table.

After die casting, annealing is performed to remove residual stress (step S2). As an example of the heat treatment condition of this annealing, a condition for holding the die cast molded product at about 250 ° C. for 4 hours is adopted. Next, each part of the cylinder block is machined to adjust its shape (step S).
3). Subsequently, burnishing is performed on the cylinder bore (step S4), and further, boring processing is performed (step S5), and the inner surface of the cylinder bore, which is the piston sliding surface, is finished by a compression pressing action. In step S4, finishing by burnishing may be omitted.

Next, anodizing is performed on the inner surface of the cylinder bore that has been subjected to the finishing process to reinforce the inner surface of the cylinder bore (step S6). Details of the alumite processing conditions will be described later.

Next, the alumite film is subjected to a heat treatment for crack formation (step S7). As this heat treatment condition, for example, a condition in which the entire cylinder block is heated at 250 ° C. for 30 minutes and then air-cooled is adopted. By this heat treatment, network-like cracks are formed in the alumite film as described later. This crack occurs because the aluminum alloy base material, which is the lower layer of the alumite film, has a larger thermal expansion coefficient than the alumite film, and the alumite film cannot follow the expansion of the base material.

On the surface of the alumite film, copper or zinc particles are exposed in a dispersed form. Accordingly, when a lubricating oil is used to alleviate wear, the lubricating oil is easily adsorbed to the exposed copper and zinc particles. Even in this case, a part of the exposed copper and zinc particles diffuses to the surface of the alumite film and performs a lubricating action. This can prevent the problem that the mating part is worn and that the alumite film adheres to the mating part and wears as a result.

In addition, by forming the cracks as described above, the cracks can be impregnated with a lubricating oil or a solid lubricant, and the frictional resistance of the surface of the alumite film at the time of sliding of the piston is reduced. The wear resistance of the surface is improved.

Next, burnishing is performed on the alumite film on the inner surface of the cylinder bore to further form a crack (step S8). The cracks caused by this burnishing process have a hardness of the alumite film larger than that of the aluminum alloy of the base material and a low ductility. Therefore, even if the base material extends when a pressure is applied to the alumite film by burnishing, the film may follow and extend. It arises from the inability to do so. In this case, if copper is contained in the base material, the strength of the base material can be increased by performing a heat treatment such as T6 treatment or T7 treatment. This will be described in detail later.

In such an aluminum alloy containing copper for strengthening the base material, fine bubbles are easily generated in the alumite film formed by the anodic oxidation treatment. Therefore, by performing heat treatment or burnishing after the alumite treatment, cracks can be effectively formed starting from these bubbles.

FIG. 4 shows the shape of the crack described above. FIG.
As shown in plan view in (A), a network-like crack having a size of about 0.1 to 5 mm is formed on the surface of the alumite film. As shown in the sectional view of FIG.
It has a width of about 0.1 to 10 μm and a depth of about 30 to 50 μm.

By impregnating such a mesh-like crack with a lubricating oil or a solid lubricant by coating or the like, the lubricating action is enhanced as compared with the case of pinholes scattered in a dotted manner or cracks formed in one direction. Therefore, the frictional resistance of the surface of the alumite film during sliding of the piston is greatly reduced, and the wear resistance of the sliding surface is greatly improved. As the solid lubricant, for example, amorphous fluorine resin, molybdenum disulfide, tungsten disulfide, graphite, carbon fluoride, boron nitride, and the like can be used.

An example of burnishing conditions for forming such a crack is as follows. The radius of the cylinder before machining is r, the radius of the cylinder after machining is r + Δr, and the strain generated on the inner surface of the cylinder by machining is ε = Δr / r. Δr × 2 is called a burnish amount. As an example, the range of ε is 0.00
01 to 0.005, and the amount of burnishing on the inner surface of the cylinder having a size of φ70 before processing is 0.01 to 0.315 mm.

Cracks are formed in the alumite film by the above-described heat treatment (step S7) and burnishing (step S8). The heat treatment (step S
7) and burnishing (step S8) may be performed only on one of them and the other may be omitted.

Subsequently, the surface of the alumite film on which the crack has been formed is honed to finish the surface (step S9). Thus, the manufacturing process of the sleeveless cylinder block including the alumite treatment on the inner surface of the cylinder bore is completed.

FIG. 5 is a flowchart showing the steps of manufacturing a cylinder block in which a sleeve is cast. First,
An aluminum alloy pipe material serving as a sleeve material is prepared (step S10). Table 3
Or the cast materials shown in Tables 2 and 4 can be used.

When the wrought aluminum alloy shown in Table 3 is used, the raw material is machined as it is to produce the pipe material. When using the cast materials in Tables 2 and 4, the pipe material is machined as it is after casting, or is machined after forging after casting. Tables 2 and 3
Alternatively, the above-mentioned pipe material can be prepared by first pulverizing the materials shown in Table 4 and then powdering these powders alone or by mixing them and then subjecting them to predetermined machining through a forging process.

In order to increase the wear resistance, Table 2 was used.
In addition to the components shown in Nos. 1 to 4, metal carbides such as SiC having high hardness and other intermetallic compounds may be mixed.

Next, the pipe material is subjected to a predetermined solution treatment and age hardening treatment by T6 treatment to increase the strength (step S11). Subsequently, the pipe material is machined into a sleeve shape (step S12). Further, T6 processing is performed on the sleeve to increase the strength (step S13). Table 5 shows the T6 treatment conditions for this sleeve material.
Shown in In addition, when using the material of Table 2 or Table 3,
The same as the T6 processing condition in AC8A.

The sleeve thus produced is cast into a cylinder block and cast by die casting (step S14). The materials shown in Table 2 are used for the material of the cylinder block, as in the case of the above-described sleeveless case.

After manufacturing the cylinder block into which the sleeve is cast as described above, the cylinder block is
As in the sleeveless flow of FIG. 3 described above, each processing of steps S2 to S9, ie, annealing for removing residual stress (step S2), machining of each part of the cylinder block (step S3), burnishing of the cylinder bore Machining (step S4), boring of the cylinder bore (step S5), alumite treatment of the inner surface of the cylinder bore (step S6), heat treatment for crack formation (step S7), and burnishing (step S8),
And finishing honing (step S9). As described above, the manufacturing process of the cylinder block in which the sleeve is cast including the alumite treatment of the inner surface of the sleeve is completed.

FIG. 6 is a flowchart showing the steps of manufacturing a sleeve press-fit type cylinder block. As in the sleeveless case described above, the cylinder block is formed by die casting (step S1), the residual stress is removed (step S2), and each part is machined to form a cylinder block (step S3).

On the other hand, as in the case of the sleeve casting type, the aluminum alloy pipe material (step S10)
6 (step S11), machining (step S12), and T6 (step S12).
13) Manufacture the sleeve.

Using the separately manufactured cylinder block and sleeve, the sleeve is pressed into the cylinder bore of the cylinder block (step S15). Thereafter, the cylinder block into which the sleeve has been press-fitted is subjected to the processes in steps S3 to S9, that is, each part of the cylinder block, in the same manner as in the flow of the sleeveless type shown in FIG. 3 and the flow of the casting type shown in FIG. Machining (step S3), cylinder bore burnishing (step S4), cylinder bore boring (step S5), alumite treatment of the cylinder bore inner surface (step S6), heat treatment for crack formation (step S7), and burnishing (step S7) S8),
And finishing honing (step S9). As described above, the manufacturing process of the cylinder block for press-fitting the sleeve including the alumite treatment on the inner surface of the sleeve is completed.

Although the sleeveless cylinder block 103 is formed by die casting which is a high-pressure casting as in the embodiment of FIG. 3, it may be replaced by a gravity casting or other low-pressure casting. In that case, the material of the cylinder block 103 is AC2 of the material shown in Table 2.
Any of A, AC2B, AC4B, and AC4D is used. When the sleeve is cast or press-fitted into the cylinder block 103 as in each of the embodiments of FIGS. 5 and 6, the material of the cylinder block 103 may be AC3A, AC4A, or AC4CH of the material shown in Table 1. When forming by die casting, ADC1, AD
C3 may be used.

FIG. 7 is a flowchart of a piston manufacturing process of the internal combustion engine according to the embodiment of the present invention. First,
A piston material having a rough piston shape is formed by casting or forging an aluminum alloy (step S30).
Any one of alloys 1 to 5 shown in Table 4 can be used as the aluminum alloy serving as the piston material.

In order to increase the abrasion resistance, Table 4 was used.
In addition to the components shown in the above, metal carbides such as SiC having high hardness and other intermetallic compounds may be mixed.

Next, in order to increase the strength, T6 shown in Table 5 was used.
Alternatively, a heat treatment of T7 shown in Table 6 is performed (step S3).
1). The T7 treatment is a heat treatment in which the aging treatment after the solution treatment is lengthened and the stabilization is enhanced, as compared with the T6 treatment described above.

Next, each part of the piston is machined (step S32). In this machining process, pin holes for inserting the piston pin, ring grooves for mounting the piston ring, and holding the piston in a holding jig that holds the piston in the electrolytic solution during alumite processing or plating processing described later Processing is performed to obtain the shape to be formed.

Subsequently, an alumite treatment described later is performed on the outer surface of the piston including the pin hole and the ring groove of the piston (step S33).

Next, machining of the outer surface of the piston is performed (step S34). In this outer surface processing step,
The shape of the outer peripheral surface of the piston is adjusted. Thereafter, finishing is performed according to the accurate cam profile of the piston shape (step S35). Finally, the center boss formed on the top surface of the piston for piston processing is deleted.

FIG. 8 is a block diagram of a stationary bath for performing alumite treatment on the piston. The alumite treatment of the piston
In the alumite treatment apparatus shown in FIG. 2 described above, a cylindrical electrode tube is disposed instead of the cylinder block 103, and a piston support rod is disposed instead of the electrode rod 129 on the inner side of the support base 116. On the inside, instead of the electrode rod 129, a piston is placed on the piston support rod with the head part upward, and the electrode cylinder is connected to the negative electrode side of the DC power supply 130, and the piston is connected to the positive electrode side of the DC power supply 130, respectively. The present invention may be embodied in such a manner that the electrolyte is circulated between the outer skirt and the electrode tube.

For the alumite treatment, as shown in FIG. 8, a stationary bath in which a piston is immersed in an electrolyte bath may be used. As shown in the figure, an electrolyte solution 151 is accommodated in an electrolyte solution tank 150, and a piston 153 held by a holder 152 is immersed in the electrolyte solution. This holder 1
52 holds two pistons 153 in two upper and lower holding frames 152a, respectively.
3 is shown. Such a holder 15
2 may be further immersed in the electrolyte bath 150 in parallel with the drawing. Cathode plates 154 are arranged on both sides of the piston 153. The holder 152 for holding the piston is connected to the anode of the DC power supply 155, and the cathode plate 154 is connected to the cathode of the DC power supply 155. With such a configuration of the stationary bath (electrolyte tank 150), the piston 1
An alumite film is formed on the surface of 53 by anodic oxidation.

In FIG. 8, reference numeral 200 denotes a radiator for cooling the electrolyte, 201 denotes a discharge nozzle for discharging a cooling liquid for the electrolyte, 202 denotes a circulation path for cooling the electrolyte, and 203 denotes a circulation path for cooling the electrolyte.
Is a circulation pump. The low-temperature, low-pressure liquid-phase refrigerant that has passed through an expansion valve (not shown) is passed through a low-pressure line 204 to a radiator 200.
To the evaporating coil 204a. During the alumite treatment, a rise in the temperature of the anodized layer of the piston 153 is prevented, so that a decrease in the hardness of the anodized layer can be prevented. The lower part of the bathtub 150 or the piston 153
The temperature is detected by a temperature sensor 205 provided in the piston, and the controller 206 increases the flow rate of the electrolyte flowing through the circulation path or increases the refrigerant discharge pressure of a compressor (not shown) to increase the alumite of the piston 153 as the temperature increases. The temperature rise of the treatment layer may be prevented. Alternatively, the temperature may be detected by a temperature sensor 205 ′ downstream of the radiator 200, and the temperature may be controlled to 30 ° C. or less. Thus, it is possible to more reliably prevent the temperature of the alumite-treated layer from being raised during the alumite treatment, and to more reliably prevent the hardness of the alumite layer from decreasing. Also,
It is preferable to arrange the piston pin hole in the discharge direction of the coolant from the discharge nozzle 201. Further, the radiator 200 may be cooled with groundwater or may be air-cooled.

It is to be noted that the piston 153 is generally not subjected to finishing after the alumite treatment. In that case, in consideration of an increase in size due to the alumite treatment, in each machining step shown in FIG. Is applied.

FIG. 9 shows an alumite treatment process (step S6) in each of the cylinder block production flows (FIGS. 3, 5, and 6) and an alumite treatment process (step S3) in the piston production flow (FIG. 7).
It is a detailed flowchart of 3).

First, a degreasing treatment is performed to remove oil on the surface of the base material of the aluminum alloy (step S1).
6). This degreasing treatment includes (1) an acid degreasing method and (2) an alkali degreasing method, and is performed by any one of the degreasing methods. Table 7 shows the degreasing conditions of each degreasing method.

When the degreasing process is completed, a water washing process is performed to remove the degreasing agent (Step S17).
Next, as necessary, an alkali etching process (step S18) or a mixed acid etching process (step S2)
0) is performed, and the base material surface is etched. After each etching process, a water washing process for removing the etchant is performed (step S1).
9, step S21). Table 8 shows the etching conditions for the alkali etching, and Table 9 shows the etching conditions for the mixed acid etching.

In the above alkaline etching, the surface of the base material is etched leaving silicon (Si) particles and intermetallic compound particles scattered in the base material of the aluminum alloy, and particles of silicon and intermetallic compounds are projected on the surface. The surface of the base material is removed. On the other hand, in the mixed acid etching, conversely, silicon particles and intermetallic compound particles are etched, and dents are formed on the surface of the base material in which the silicon particles and intermetallic compounds are removed. In the mixed acid etching shown in Table 9, copper, zinc, and the like exposed on the surface of the base material do not elute.

In such an etching treatment, when there is a possibility that the surface is not sufficiently removed in the degreasing treatment in the preceding step, both the alkali etching and the mixed acid etching are performed to completely remove the surface layer. It is desirable to increase the reliability of the anodic oxidation treatment performed in a later step.

The depression at the mark where the silicon particles and the intermetallic compounds are removed by the mixed acid etching can be used as a depression for impregnating oil or a solid lubricant.

Next, the surface of the base material thus etched is subjected to anodizing treatment to form an alumite film (step S22). This anodizing treatment is performed using, for example, the alumite treatment apparatus shown in FIG.
Table 10 shows examples of the alumite treatment.

Table (A) shows the ADC 12 in Table 2 described above.
This is an example of anodizing the inner surface of the cylinder bore of a sleeveless cylinder block made of
Is an example in which the alumite treatment is applied to the inner surface of the sleeve of the cylinder block made of A6061 in Table 1 and cast with the sleeve. Table (C) corresponds to Table 4 described above.
This is an example in which an alumite treatment is applied to a piston made of alloy 5 of the present invention.

In this embodiment, as shown in Table 10 above, oxalic acid and citric acid were added as the electrolytic solution in addition to sulfuric acid for the following reasons. Sulfuric acid has a strong alumite film dissolving power and dissolves this alumite film after an anodized film (anodized film) is formed by electrolysis. For this reason, pinholes formed on the surface of the alumite film during the anodizing treatment are dissolved and expanded,
As a result, the surface hardness of the film decreases. In particular, copper or zinc exposed on the surface of the film is easily eluted by sulfuric acid, pinholes grow from this elution point to easily become large porous, and the surface hardness of the film decreases. Although the porous portion has an oil-impregnating function, the surface hardness of the alumite film is reduced, so that the film is easily worn. In addition, copper or zinc diffuses into the surface of the alumite film due to sliding, and the function of protecting the surface of the film is lost. However, by adding oxalic acid or citric acid as in the present embodiment, the film dissolving power of sulfuric acid is reduced and the film hardness can be increased, and particularly, the elution of copper or zinc exposed on the film surface is reduced. It is prevented and wear resistance is improved.

In this case, when the entire electrolytic solution is oxalic acid or citric acid, the electric conductivity of the electrolytic solution, that is, the charge transport function is reduced, and the reaction rate is reduced. However, by including an appropriate amount of sulfuric acid in the electrolytic solution, the electrical conductivity is increased, the processing time required to obtain an alumite film of a predetermined thickness is shortened, and the alumite film formed because the proportion of sulfuric acid is small. Can prevent the hardness of the film from decreasing due to the dissolving action of the film.

FIG. 12 is a diagram showing the effect of bath temperature on hardness with constant electrolysis conditions. In the figure, a shows current density of 3 A / dm ² (ampere /
100 cm ² ), current waveform: direct current, electrolysis time: 20 minutes, electrolyte solution is data when alumite treatment was performed under the conditions of sulfuric acid concentration: 20 g / l, oxalic acid + citric acid concentration: 40 g / l. When the bath temperature is 30 ° C. or lower, Hv 380 or higher can be obtained. For other aluminum alloys in Tables 1 and 2,
By performing the alumite treatment while controlling the bath temperature to about 30 ° C. or less, the alumite film has a hardness H that can provide practically sufficient wear resistance as the inner peripheral surface of the cylinder on which the piston slides.
v380 or more.

Further, FIG. 2 (b) shows that the electrolytic solution is made of sulfuric acid having a concentration of 20.
g / l, oxalic acid + citric acid concentration: 0 g / l, and the other conditions are the same as those in (a).
It shows that Hv 380 or more can be obtained at a temperature of not more than ℃.

FIG. 13 is a graph showing the effect of oxalic acid and citric acid concentrations on the film thickness and hardness in a state where the sulfuric acid concentration is maintained at a constant 20 g / l. As other electrolysis conditions, the aluminum alloy to be treated is A6061, current density is 3 A / dm ² , current waveform is DC, electrolysis time is 20.
And the bath temperature is 13 ° C. Sufficient film thickness, for example, 25μ
In order to obtain m or more, the combined concentration of oxalic acid and citric acid needs to be 13 g / l or more.

FIG. 14 is a graph showing the effect of the electrolyte composition on the film thickness and hardness when the oxalic acid and citric acid concentrations are used as parameters when the sulfuric acid concentration is changed.
As other electrolysis conditions, the aluminum alloy to be treated is A6061, current density is 3 A / dm ² , current waveform is DC,
Electrolysis time: 20 minutes, bath temperature 13 ° C. When oxalic acid and citric acid were not mixed with the electrolyte solution (A = 0), it was shown that it was difficult to form an alumite film when the sulfuric acid concentration was 20 g / l or less. Is formed, the film hardness is substantially Hv3
It is about 00, and it cannot be Hv380 or more necessary for abrasion resistance. As can be seen from A = 20, 40, 60, by mixing oxalic acid and citric acid in the electrolytic solution, it is possible to form an alumite film even in a wide range of sulfuric acid concentration, and to improve abrasion resistance. The required hardness of Hv 380 or more can be obtained. As can be seen from the figure, in this case, the film thickness increases as the sulfuric acid concentration increases, that is, the electrolysis time for obtaining a predetermined film thickness can be shortened.

After the alumite film is formed by the anodic oxidation treatment as described above, a washing treatment is performed to remove the electrolytic solution (Step S23), and a secondary electrolytic treatment is performed (Step S2).
4). In this secondary electrolysis treatment, a solid lubricant is deposited by electrolytic action on the bottom of the pinhole formed innumerably on the surface of the alumite film and deposited, and the inside of the pinhole is filled with the solid lubricant from the bottom. Fill. This allows
The lubricity of the film surface is further improved, and the wear resistance is further improved.

Subsequently, the electrolyte of the solid lubricant is removed by washing with water (step S25), and the moisture is removed by air blow to dry the cylinder block, thereby completing the alumite treatment (step S26).

FIGS. 10 and 11 are cross-sectional views of the surface of the base material in each step of the manufacturing process of the above-described cylinder block and piston. FIG. 10 shows, in order, a flow in which the anodizing process is performed by omitting the etching process after the degreasing process. FIG. 11 shows, in order, a flow in which alumite treatment is performed after mixed acid etching is performed.

FIG. 10A shows the state after the degreasing treatment. Silicon particles, metal carbides such as SiC, and other intermetallic compound particles 141 are scattered in the base material 140 made of an aluminum alloy. Surface 140a of this base material 140
Dirt such as oil is removed by degreasing.

After the degreasing treatment, an alumite treatment is performed to form an alumite film 142 on the base material 140 as shown in FIG. Silicon particles 141 are also scattered in the alumite film 142. Alumite coating 1
Bubbles 143 are generated in 42. This bubble 143
As described above, a large amount occurs when the base material 140 contains a copper component.

Subsequently, heat treatment or burnishing is performed, and as shown in FIG.
Crack 144 is formed in the substrate. Next, as shown in FIG. 3D, honing is performed, and the alumite film 1 is formed.
The surface 142a of 42 is finished.

FIG. 11A shows a state after the mixed acid etching process. The silicon particles 141 on the surface of the base material 140 are removed by etching to form a recess 145.
An alumite treatment is performed in this state, and an alumite film 142 is formed on the surface of the base material 140 as shown in FIG. The surface of the alumite film 142 has a dent 1
45 remain. Subsequently, heat treatment or burnishing is performed to form cracks 144 in the alumite film 142 as shown in FIG.

Next, as shown in FIG. 9D, honing is performed to finish the surface 142a of the alumite film 142. In this case, the alumite film 142 includes
Depression 14 due to mixed acid etching together with crack 144
5, the impregnation amount of the oil or the solid lubricant can be increased. Table 11 shows the chemical composition of the alumite film when the alumite treatment was performed on the Al-10Si-4Cu aluminum alloy contained in the alloy 2 shown in Table 4. The alumite film made of sulfuric acid in the table means that sulfuric acid (concentration: 200 g / l) is used as the electrolyte.
What is an alumite film formed by an alumite treatment performed at a current density of 3 A / dm ² (ampere / 100 cm ² ), a current waveform: DC, electrolysis time: 20 minutes, and a bath temperature of 0 to 5 ° C. Oxalic acid mixed solution (oxalic acid concentration 40 g / l + citric acid concentration 0
２０20 g / l + sulfuric acid concentration 100 g / l), current density 3 A / dm ² (ampere / 100 cm ² ), current waveform: DC, electrolysis time: 20 minutes, bath temperature: alumite by alumite treatment performed at 15 ° C. It is a film.

As can be seen from 1) of Table 11, the base material 100
86 g of Al contained in g is oxidized and changed to 162.5 g of Al ₂ O ₃ . On the other hand, the base material 11
4 g of Cu atoms contained in 0 g are dissolved in sulfuric acid in an alumite treatment using sulfuric acid as an electrolytic solution, and 0.1 g of Cu atoms are dissolved in sulfuric acid.
In the alumite treatment using an oxalic acid mixture as an electrolyte, dissolution in sulfuric acid is suppressed to about 1 to 3 g. Table 11-2) shows the percentage of each component calculated from Table 11 1) in percentage.

A3003, A6061, AC shown in Table 1
Since 3A, AC4A, AC4C, AC4CH and the like contain a small amount of copper or zinc, elution of copper or zinc from the surface of the alumite film can be prevented by performing an alumite treatment using an oxalic acid mixture as an electrolyte, The surface hardness can be prevented from lowering due to the porous alumite film, and the wear resistance of the sliding portion can be increased.
However, since the amount of copper and zinc exposed on the surface of the alumite film is small, even if copper or zinc diffuses to the surface of the alumite film when lubricating oil is not used for the sliding part, the amount becomes small, and the lubricating effect is not sufficient. Therefore, the wear resistance of the sliding portion cannot be made sufficient. Also, sufficient strength cannot be obtained regardless of the presence or absence of heat treatment.

On the other hand, A707 shown in Table 2, 3 or 4
5, AC2A, AC2B, AC4B, AC4D, AC8
A, AC8B, AC8C, or gold or gold 1-5, etc., 0.7-7% of either copper or zinc in an aluminum alloy, or 0.7-10% in total of both.
By containing, it is possible to increase the strength of the aluminum parts sliding relatively to the mating parts such as pistons, cylinders, connecting rods, valve lifters, etc., formed from these aluminum alloy materials using the various forming methods described above, In particular, by performing a solution treatment, one or both of copper and zinc can be surely dispersed and solid-dissolved in an Al crystal, so that the strength is increased. Further, the strength and hardness are further increased by performing an age hardening treatment. Can be.

However, when anodizing is to be performed to obtain an aluminum alloy part having a high surface hardness,
When sulfuric acid is used as the electrolytic solution, copper, zinc and the like are eluted, and as a result, the alumite film can only have a surface hardness lower than the hardness of the alumite film made of dense Al ₂ O ₃ .

The inventor of the present application has found that the use of an oxalic acid mixed solution as an electrolytic solution can reduce the elution of copper, zinc, etc. from the alumite film, and the hardness of the alumite film and the copper in the alumite film. , Zinc content was found.

FIG. 15 shows that Al-10Si-4 was used as a base material.
By using Cu aluminum alloy, JIS 5056 aluminum alloy, and 7N01 aluminum alloy, using an oxalic acid mixed solution as an electrolytic solution, and changing the electrolytic conditions (sulfuric acid concentration and processing time), the copper (Cu) in the alumite film is changed. ) Or the results of an experiment for examining the surface hardness (Hv) of the alumite film when the zinc (Zn) content% was changed.

From the figure, it can be seen that in order to obtain sufficient hardness, the content of copper or zinc in the alumite film should be 0.5% or more. Copper or zinc is dispersed in the alumite coating and is also dispersed and exposed on the surface, so that the abrasion resistance can be improved in relation to the sliding partner component.

One of copper or zinc in the alumite film
One or more content percentages must be 0.5% or more,
More preferably, one or both of the copper and zinc in the coating is Al.
_Two O _Three Aluminum to spread between and on the surface
Either copper or zinc as the base material for the aluminum alloy parts
0.7 to 7% for one, or 0.7 to 1 in total
0% content, and then use as electrolyte
It is necessary to perform alumite treatment using a mixture of uric acid.
Yes, this ensures the above-mentioned effect of improving hardness
You.

The base material of an aluminum alloy component containing 0.7 to 7% of any one of copper and zinc or a total of 0.7 to 10% of a plurality thereof has sufficient strength.
The strength can be further increased by performing a solution treatment or an age hardening treatment.

Here, the solution treatment and the age hardening treatment cause residual strain in the base material of the aluminum alloy part, and therefore it is desirable to perform the treatment before machining. Usually, an alumite film is often formed on a machined surface, so that a solution treatment or an age hardening treatment is performed before the anodizing step.

However, when the alumite film is cracked to have an oil-impregnating function, the solution treatment and the age hardening treatment may be performed after the anodizing step. In this case, it is preferable to polish the alumite film in order to obtain sufficient dimensional accuracy. The solution treatment may be performed before the anodic oxidation step, and the age hardening treatment may be performed after the anodic oxidation step in order to reduce the degree of occurrence of cracks.

In order to expose copper, zinc or the like to the surface of the alumite film formed on the base material surface of the aluminum alloy component containing one or more of copper and zinc, the base material surface was machined. Thereafter, an anodic oxidation treatment may be performed. In addition, etching according to Table 8 or Table 9 may be performed before the anodic oxidation treatment. Further, the alumite film may be polished.

FIG. 16 shows the relationship between the relative mobility of metal ions taken into the alumina film with respect to Al ³⁺ ions and the metal-oxygen binding energy. As can be seen from the figure, an oxalic acid mixed solution or the like is added to an aluminum alloy containing copper or zinc.
When anodizing treatment is performed using an electrolytic solution that prevents electrochemical elution of copper and zinc, copper and zinc that form a solid solution in the aluminum alloy during the anodizing process are formed without eluting into the electrolytic solution. It is ionized in the growing alumite film and moves and disperses actively. Thereby, the alumite film does not become porous and copper and zinc are uniformly dispersed, so that the hardness of the alumite film can be increased.

17 to 19 are views for explaining the second embodiment of the present invention. FIG. 17 is an enlarged sectional view of a piston, FIG. 18 is an enlarged view of an alumite film, and FIG. 19 is an enlarged sectional view of a piston ring. FIG.

17 and 18, reference numeral 1 denotes a piston. The piston 1 is made of an aluminum alloy (AC8A to AC8C, AC9A, AC9B, etc. shown in Table 4), and has a top surface 1a and an inner surface 1a. 1b is a cast surface that has not been machined and its outer peripheral surface (cylinder sliding surface) is machined into a predetermined shape. The first and second ring grooves 7a and 7b are formed on the outer peripheral surface by machining.
Are formed, and a piston ring is mounted in the first and second ring grooves 7a and 7b.

A pair of pin bosses 1c, 1c are formed inside the piston 1 so as to bulge inward, and a piston pin hole 7c is formed in the pin bosses 1c, 1c so as to penetrate in the radial direction. ing. The piston pin 5 is rotatably inserted into the piston pin hole 7c. A locking groove 7d is formed at both outer ends of the pin hole 7c, and snap rings 8, 8 are mounted in the locking groove 7d. This snap ring 8 is used for the piston pin 5
In order to prevent the movement in the axial direction.

The inner surface 1b 'of the inner surface 1b of the piston 1 and the inner surface 1b' of the pin bosses 1c, 1c facing the small ends of the connecting rods, and the inner surface of the piston pin hole 7c are anodized by anodizing. An alumite film 10 is formed. The alumite film 10 has a film thickness (however, since the film thickness cannot be made completely uniform over the entire film, the maximum film thickness of the film thickness which varies within a certain width in the spread of the film is herein used. Is set within the range of 30 ± 10 μm, and as a result, the film surface roughness is controlled to Ra 1.5 to 3.0 as described below.

The alumite coating 10 is such that the surface a of the coating main body 10a is located outside the exposed surface b of the Si 10b, in other words, the Si 10b is
It has a surface shape that does not protrude from the surface.

[0099] The particles 10c of one or both of copper and zinc contained in the base material are also contained in the alumite film 10 and are exposed to the surface of the film 10. The Si10b is eluted by etching using a mixed acid containing nitric acid as shown in Table 9 and is in a state recessed from the surface of the alumite film 10. In this mixed acid etching, copper exposed on the surface of the alumite film 10 or The zinc particles 10c did not elute,
Wear resistance can be improved in relation to the inner circumference of the cylinder.

FIG. 19 is a sectional view of a piston ring mounted on the piston 1. As shown in FIG. This piston ring
It comprises a ring body 156 and a coating 157 formed by surface-treating the outer peripheral surface which is the sliding surface thereof. This ring body 1
Table 12 shows examples of the 56 ring materials, and Table 13 shows an example of the treatment of the coating portion 157 obtained by subjecting the ring material to surface treatment.

In any of the treatment examples shown in Table 13, when the covering portion 157 slides on the inner peripheral surface of the cylinder bore subjected to the alumite treatment of the above embodiment, the covering portion 157 has good compatibility with the inner peripheral surface of the cylinder bore. In addition, the wear of the alumite treatment layer on the inner peripheral surface of the cylinder bore can be reduced. In particular, one or both particles of copper and / or zinc contained in the cylinder bore are exposed on the surface of the alumite treatment layer on the inner peripheral surface of the cylinder bore, so that wear of both the piston ring and the inner peripheral surface of the cylinder bore can be reduced. .

Further, after the alumite treatment, cracks are formed as described above, and the cracks are impregnated with a lubricating oil or a solid lubricant, or an intermetallic compound such as Si particles exposed on the inner peripheral surface of the cylinder bore is subjected to mixed acid etching. The effect is remarkable in the case where the alumite treatment is applied to the material removed by the treatment, and the recesses are more positively formed in addition to the cracks so that the lubricating oil or the solid lubricant is more impregnated.

Also, the surface is made of Si particles or SiC having high hardness.
In the case of forming an alumite film in a state where metal carbides and intermetallic compounds other than the metal carbide are exposed, the hardness of the alumite film side is increased and wear of the inner peripheral surface of the cylinder bore is reduced, The compatibility with the film can be improved, and the sealing performance against lubricating oil and combustion gas can be improved.

Further, the ring main body 156 constantly collides with the ring groove surface while being housed in the ring groove.
Since it is possible to impregnate the concave portion formed on the surface of the alumite-treated layer of the ring groove based on the removal of cracks, Si particles and the like with lubricating oil or solid lubricant, the ring groove surface,
Both of the ring body 156 can be prevented from being hit and worn. The ring main body 156 can also prevent abrasion of the ring groove surface even when Si particles or an intermetallic compound such as high-hardness SiC is contained in the ring groove exposed on the surface. In each case,
By adopting the ring material of the ring main body 156 exemplified in Table 12, the familiarity between the ring groove surface and the ring main body 156 can be improved, and oil or combustion gas can be prevented from passing through the back surface of the ring.

[0105]

[Table 1]

[0106]

[Table 2]

[0107]

[Table 3]

[0108]

[Table 4]

[0109]

[Table 5]

[0110]

[Table 6]

[0111]

[Table 7]

[0112]

[Table 8]

[0113]

[Table 9]

[0114]

[Table 10]

[0115]

[Table 11]

[0116]

[Table 12]

[0117]

[Table 13]

[0118]

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an internal combustion engine according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an alumite processing apparatus according to the first embodiment.

FIG. 3 is a flowchart of a sleeveless cylinder block manufacturing process of the first embodiment.

FIG. 4 is an explanatory diagram of a crack according to the first embodiment.

FIG. 5 is a flowchart of a sleeve casting cylinder block manufacturing process of the first embodiment.

FIG. 6 is a flowchart of a sleeve press-fit cylinder block manufacturing process of the first embodiment.

FIG. 7 is a flowchart of a piston manufacturing process according to the first embodiment.

FIG. 8 is a configuration diagram of a still bath for alumite-treating the piston according to the first embodiment.

FIG. 9 is a flowchart of an alumite process of the first embodiment.

FIG. 10 is a sectional view sequentially showing the aluminum component manufacturing process of the first embodiment.

FIG. 11 is a sectional view sequentially showing another manufacturing process of the aluminum component of the first embodiment.

FIG. 12 is a graph showing the effect of bath temperature on the hardness of the alumite of the first embodiment.

FIG. 13 shows that the sulfuric acid concentration in the first embodiment is constant (20 g).
6 is a graph showing the effect of oxalic acid and citric acid concentrations on the film thickness and hardness in the state of (1 / l).

FIG. 14 is a graph showing the effect on film thickness and hardness when the sulfuric acid concentration of the first embodiment is changed, using oxalic acid and citric acid concentrations as parameters.

FIG. 15 is a graph showing the effect of the copper content in the alumite coating of the first embodiment on the hardness.

FIG. 16 is a metal oxygen binding energy-relative mobility characteristic diagram for explaining the effect of the first embodiment.

FIG. 17 is an enlarged sectional side view of a piston according to a second embodiment of the present invention.

FIG. 18 is an enlarged schematic sectional view of an alumite film of the piston according to the second embodiment.

FIG. 19 is an enlarged sectional view of the piston ring of the second embodiment.

[Explanation of symbols]

1,117 Aluminum alloy parts (piston, cylinder liner) 10,142 Alumite coating

Claims (5)

[Claims] An alumite film formed on the surface of a base material of an aluminum alloy component used for a sliding portion is provided with 0.5% or more of either copper or zinc or a total of 0.1% of both. An aluminum alloy component containing not less than 5% and at least one of the contained copper and zinc particles exposed on the surface of the alumite film. 2. The aluminum alloy component according to claim 1, wherein the base material of the aluminum alloy component comprises one of copper and zinc in a range of 0.7 to 7%.
% Or an aluminum alloy containing 0.7 to 10% in total. 3. A method of manufacturing an aluminum alloy part, wherein an alumite film is formed on the base material surface of the aluminum alloy part by anodizing treatment through an electrolytic solution, wherein the aluminum alloy part is made of one of copper and zinc. One to 0.7 to 7%, or both to a total of 0.7 to 1
Use aluminum alloy containing 0%,
A method for manufacturing an aluminum alloy component, wherein the electrolytic solution contains sulfuric acid and further contains either oxalic acid or a mixed solution of oxalic acid and citric acid. 4. A method for manufacturing an aluminum alloy part according to claim 3, wherein a solution treatment and an age hardening treatment are performed before or after the anodizing step of forming an alumite film via the electrolytic solution. . 5. The method according to claim 3, wherein a solution treatment is performed before the anodizing step of forming an alumite film via the electrolytic solution, and an age hardening treatment is performed after the anodizing step. Manufacturing method of aluminum alloy parts.