CN1500019A - Closed forging method, forging manufacturing system using the method, forging dies used in the method and system, and preforms or yokes manufactured by the method and system - Google Patents

Abstract

A closed forging method for producing a forged product includes preparing as a forging material a cylindrical cast ingot that has a volume the same as the volume of a forged product and assumes a shape having an upper surface, a lower surface and a side surface and containing no angular portion; and applying pressure to the side surface of the forging material. The shape has a ratio of the lateral length of a projection profile of the forging material as viewed in the direction perpendicular to the direction of pressure application to a length of the forging material as measured in the direction of pressure application is 1 or less. The forged product obtained is a preform of an upper arm or a lower arm with a plurality of branches that is a suspension part for a vehicle or a yoke with a plurality of branches that is a joint part employed in a vehicle suspension. The preform or yoke has metal flow lines along each branch and exhibits enhanced mechanical strength.

Description

Closed forging method, forging manufacturing system using the method, forging dies used in the method and system, and preforms or yokes manufactured by the method and system

Related Application Cross Reference

This application is an application filed under 111(a) of U.S.C. 35, which claims a patent filed under 119(e)(l) of U.S.C. Priority of provisional application No. 60/281,810 filed on .

technical field

The present invention relates to a closed forging method, a forging manufacturing (production) system using the method, a forging die (forging die) used in the method and system, and a forging die for a vehicle manufactured by the method and system The suspension part and the part consist of a preform or yoke (fork, prong).

Background technique

The coupling for the vehicle suspension comprises a yoke 43 having a plurality of branches (branches) 21 , 22 and 23 shown in FIG. 2 .

Typically, as shown in FIG. 3, the yoke is forged from a solid round bar 31 to form a forged product with flash 32 formed around its periphery.

In another way, as shown in FIG. 4, the article 43 (ie, the yoke) is manufactured by machining the portion 42 of the preform 41 of the yoke which is extruded and cut into substantially the same shape as the article.

Recently, aluminum alloys are increasingly used in the manufacture of vehicle suspension components instead of iron to reduce the weight of the components. Vehicle suspension components are manufactured by forging to increase their mechanical strength and reduce the raw materials used to manufacture the product. Examples of vehicle suspension components include an upper arm and a lower arm.

Since the upper arm 54 shown in FIG. 5, that is, a vehicle suspension component, has branches 51, 52 and 53 extending in three directions, it is difficult to manufacture the upper arm with a single forging step. Therefore, usually by first manufacturing an upper arm preform 61 shown in FIG. It assumes the shape of the upper arm 54 shown in FIG. 5 .

Specifically, a solid round bar 71 as shown in FIG. 7 is forged with a forging die, and then a trimming (trimming) die is used to remove the flash 72 from the forged body, thereby making a forged preform 73 of the upper arm .

The preform 73 then undergoes a plurality of forging steps to obtain a vehicle upper arm 74 . Here, in order to reduce the waste of material caused by the formation of flash, a forging die is used, the structure of which can allow a solid round bar material to be produced into multiple upper arm preforms 73a in one forging step.

Meanwhile, a known closed forging method without forming flash is used to forge a disc-shaped material 82 into a product of simple shape, that is, for example, a simple round or cylindrical product. , a video tape recorder (VTR) cylinder 81 as shown in FIG. 8 .

JP-A HEI 1-166842 discloses a method of manufacturing a product with a plurality of branches by closed forging. In the method disclosed in this publication for the manufacture of an article having a plurality of radially extending branches as shown in FIG. The cavity in the middle, thereby making the radially extending branch 92 by closed forging.

In the conventional method of forming burrs shown in FIG. 3, a trimming step is required to remove the burrs after the forging step. In this method, since unnecessary burrs are formed around the forged body, the yield based on the forged material is low. In addition, since the projected area of the forged body in the direction perpendicular to the pressing direction is large, a large and expensive forging machine capable of applying a high load (pressure) is required, resulting in high manufacturing costs.

Also, in the conventional method of FIG. 4, in which the yoke 43 is manufactured by machining the preform 41 obtained by cutting an extruded material, since the portion 42 is subjected to machining, it is necessary to leave room for the machining. Large margins are produced, resulting in low yields of preform-based finished products. In addition, this method results in high manufacturing costs due to the machining steps required.

The above conventional method of manufacturing a preform for an upper arm or a lower arm as a vehicle suspension component requires a trimming step to remove flash after the forging step. In this method, material-based preform yields are low due to unwanted flash forming around the preform. In addition, since the projected area of the forged body in the direction perpendicular to the pressing direction is large, a large and expensive forging machine capable of applying a high load is required, resulting in high manufacturing costs.

In the closed forging method disclosed in JP-A HEI 1-166842, pressure is applied in a direction perpendicular to the cut surface of a cylindrical material to cause plastic flow of the material to form radially extending branches 92. Therefore, when the branches 92 are long or cannot reach a consistent length (that is, each branch has a different shape), forging defects such as underfill and Overlapping (shingling) on the surface of forged products.

In summary, it is an object of the present invention to provide: a closed forging method for manufacturing a component having a plurality of branches, wherein the load exerted on the raw material in forging is reduced and the yield of finished products based on the raw material is increased ; a forging manufacturing system using the method; and a forging die used in the method and system.

Another object of the present invention is to provide a method for efficiently manufacturing vehicle suspension components and preforms or yokes thereof at low cost.

Still another object of the present invention is to provide a mechanically strong forged product produced by plastic flow of forging material along a plurality of branches to form layers of metal flow in the plurality of branches.

The term "material" as used in the specification means an unwrought object including an ingot, forged material, cut workpiece, solid round bar, stock, cylindrical material, continuous forged round bar, disc or billet.

The term "preform" as used in the specification refers to an article which has been forged but undergoes at least one further forging step to form a finished product, including yoke preforms, upper arm preforms and upper arm forged preforms.

The term "forged product" used in the specification refers to a forged product, including components, products, finished products (final products), forged bodies, and forged products.

Contents of the invention

The present invention provides a closed forging method for manufacturing a forged product, comprising: preparing a cylindrical casting ingot as a forging material, the ingot having the same volume (V) as the forged product, which exhibits has an upper surface, a lower surface and a side surface, and does not contain convex (angular) portions; and pressure is applied to the side surface of the forged material; wherein the shape has such a proportion that the forged material is vertically The ratio of the lateral length of the projected surface in the direction of the pressing direction to the length of the forged material measured in the pressing direction is equal to or less than 1.

The forging material is a cut work (section) obtained from a round bar, the ratio (T/R) of the thickness (T) of the cut work to the diameter (R) of the cut work is 1 or less.

The volume (V) of the forged product, the thickness (T) of the cut workpiece, the longitudinal length (L) of the projected plane of the forged product in the direction perpendicular to the direction of pressure application, and the diameter (R) of the cut workpiece satisfy the following relationship Mode: $(1/3)\×L\≤R=2\×\sqrt{(V/\mathrm{T\π})}\≤L.$

The thickness (T) of the cut workpiece is 0.8-1.0 multiplied by the lateral length (t) of the projected surface of the forged product in the direction perpendicular to the direction of pressure (that is, 0.8 to 1.0 times (t)).

The forged material is made of aluminum or an aluminum alloy.

The forged article is a component having a plurality of branches free from flash removal and forming metal flow lines along the respective branches, the component being a preform for an upper or lower arm as a vehicle suspension component, or A yoke used as a connecting part in a vehicle suspension.

The present invention also provides a forging die used in the closed forging method, which includes a punch, a die and an ejector (ejector), or includes a punch and a splitter with a driving mechanism. Asana mold.

The present invention also provides a forging manufacturing system, comprising a device for cutting forging materials and a forging machine, wherein the forging machine is a forging die, comprising a punch, a die and a blank ejector, or comprising A punch and a split die with drive mechanism.

In the closed forging method according to the present invention, as described above, a cylindrical forging material having the same volume as that of the forged product is used, its shape has no convex portion, and it has such a ratio that the forging material is perpendicular to The ratio of the lateral length of the projected surface in the direction of the pressing direction to the length of the forged material measured in the pressing direction is equal to or less than 1. Since the pressure is applied on the side surface of the forged material, the plastic flow of the forged material occurs along multiple branches of the forged product, thereby forming a metal flow layer in each branch, the forged product shows improved mechanical characteristics and is not cut Traces of flying edges. This results in an increased yield of articles based on wrought material.

Since the plastic flow of the forging material occurs along a plurality of branches of the forged product, thereby forming a metal flow layer in the branches, the upper arm or the lower arm as a vehicle suspension part manufactured by the closed forging method of the present invention or as a A preform for a yoke for a connecting component in a vehicle suspension exhibits improved mechanical characteristics.

In the die used in the closed forging method of the present invention, a combination of a punch, a die and an ejector or core (liner) or a combination of a punch and a die with a driving mechanism The shape of the space defined has the same volume as that of the forged product and has such a ratio that the transverse length of the projected plane of the forged material in the direction perpendicular to the direction of pressure The ratio of the resulting lengths is equal to or less than 1. In addition, the configuration of the die enables pressure to be applied to the side surfaces of the cylindrical forged material. Therefore, the pressure applied in forging can be reduced, and the yield of products based on the forged material can be improved.

Description of drawings

Fig. 1 is the sectional view of an embodiment of the present invention, has shown the state that punch arrives at the bottom point of descent when forging the forging preform of the upper arm as vehicle suspension part;

Fig. 2 has shown the yoke of another embodiment of the present invention;

Figure 3 is a schematic diagram showing the hot forging method used to manufacture a yoke with flash formed around it;

Figure 4 is a schematic diagram showing a method for manufacturing a yoke by extrusion, cutting and machining;

Figure 5 shows an upper arm manufactured from a forged preform using another embodiment of the present invention;

Figure 6 shows the forged preform of the upper arm of another embodiment of the present invention;

Figure 7 is a schematic diagram showing the hot forging method used to manufacture an upper arm with flash formed around the upper arm preform;

Fig. 8 is a schematic view showing a closed forging method for manufacturing a cylinder of a video tape recorder (VTR);

Fig. 9 is a schematic diagram showing the closed forging method disclosed in JP-A HEI 1-166842;

Fig. 10 is a schematic diagram showing a closed forging manufacturing system according to another embodiment of the present invention;

Fig. 11 is a schematic diagram showing the structure of a closed forging die of another embodiment of the present invention;

Figure 11(a) is a perspective view showing an example of a monolithic mold; Figure 11(b) is a cross-sectional view of the mold shown in Figure 11(a); Figure 11(c) is a perspective view showing a Examples of split molds;

Fig. 12 is a schematic view showing an example of another split mold used in the closed forging method of the present invention;

Fig. 13 is a sectional view showing a state when a yoke is manufactured by a closed forging method according to another embodiment of the present invention;

Fig. 14 is a projection plane perpendicular to the pressing direction shown in Fig. 13;

Fig. 15 shows the state that the forging material is placed in the mold shown in Fig. 13 before forging;

Figure 16 shows the arrangement of forging materials and dies for forging a yoke with flash around it by the hot forging method;

Figure 17 shows a tensile test piece;

Figure 18 shows the yoke fabricated in Example 2;

Fig. 19 is a sectional view showing a state when a yoke is manufactured by closed forging in Example 2;

Fig. 20 is a projection plane perpendicular to the pressing direction shown in Fig. 19;

Fig. 21 shows the state that the forging material is placed in the die shown in Fig. 19 before forging;

Fig. 22 is a projection plane perpendicular to the pressing direction shown in Fig. 1;

Fig. 23 shows the state that the forging material is placed in the die shown in Fig. 1 before forging;

Fig. 24 shows an upper arm as a vehicle suspension component made of a forged preform according to another embodiment of the present invention;

Figure 25 shows a forged preform of another embodiment of the invention used to make the upper arm shown in Figure 24;

Fig. 26 is a sectional view showing a state in which the preform shown in Fig. 25 is manufactured by a closed forging method;

Fig. 27 is a projection plane perpendicular to the pressing direction shown in Fig. 26;

Fig. 28 shows a state where a forged material is placed in the die shown in Fig. 26 before forging, where a tensile test piece is obtained.

Best Mode for Carrying Out the Invention

In order to increase the yield of finished products based on raw materials, the inventors of the present invention conducted extensive research on the closed forging method and closed forging manufacturing system for manufacturing forged products and the relationship between metal flow in forged products and the mechanical strength of products. Research. The present invention has been accomplished on the basis of this knowledge.

The forging material used in the present invention is a cylindrical cast ingot (ingot), which has the same volume as the forged product, and which assumes a shape having an upper surface, a lower surface and a side surface, without lobes part, and the ratio of the transverse length of the projected plane of the ingot in the direction perpendicular to the direction of pressing to the length of the ingot measured in the direction of pressing is equal to or less than 1.

The expression "the forged material having the same volume as that of the forged product" used herein means that the volume of the forged material falls within the allowable volume tolerance range of the forged product. The volume gap between the forged material and the forged product is preferably equal to or less than 2%, more preferably equal to or less than 1%, based on the volume of the forged product.

Problems arise when the volume of the forged material is not the same as that of the forged product, including underfill problems in the forged product when the volume of the forged product is larger than the forged material, and when the volume of the forged product is smaller than the forged material, due Flash is formed on the forged product, and the forged product cannot be used as a finished product, or the forging die is cracked to cause failure in the manufacture of the forged product. In addition, a step of flash removal is also required. This increases the operating steps. Also, the yield of forged products based on the forged material decreases due to the removal of the flash.

The forged article produced by the method of the present invention is preferably a component with multiple branches. As used herein, "a component having multiple branches" refers to a component having multiple branches (for example, when the component is used in combination with another component, each of its branches serves as a part connected or supported by it) wherein each branch extends from its end along an arbitrary route towards a point of convergence (eg, center of gravity) that falls within a polygon formed by connecting the ends of the branches. This definition covers the case where no side branches are included in these branches, and the case where the junction of the branches falls on the endpoint of a branch.

To reduce the weight of the part, the branches may be punched with holes formed therein. The part may also be a part having a plurality of branches extending from a confluence of branches. The invention can be applied to components having branches extending symmetrically or asymmetrically with respect to their junction. Examples of the part include a yoke (yoke) as a link used in a vehicle suspension part, and upper and lower arms as a vehicle suspension part. For these components, a further increase in the mechanical strength of the branches is a desired improvement.

The present invention provides a closed forging method, which includes: preparing a cylindrical casting ingot as a forging material, which assumes a shape having an upper surface, a lower surface and a side surface, and does not contain a convex portion; and exert pressure on the side surface of the forged material; wherein the shape has such a ratio: the ratio of the transverse length of the projected plane of the ingot in the direction perpendicular to the direction of pressing to the length of the forged material measured in the direction of pressing equal to or less than 1.

"a cylinder having an upper surface, a lower surface, and a side surface, and being free of convex portions" means, for example, a cylindrical object having a bottom surface defined by a curve free of convex portions, and A truncated cone, an elliptic cylinder, and a truncated elliptical cone having a lower surface defined by a curve without a convex portion.

When the ratio of the transverse length of the projected plane of the forged material in the direction perpendicular to the direction of pressure to the length of the forged material measured in the direction of pressure exceeds 1, the projection of the forged material in the direction perpendicular to the direction of pressure The larger the area, the higher the forging load is required, and the forging load becomes too large to prevent reliable forging. Such an increase in the forging load has an adverse effect on forging both the preform of the upper arm or the lower arm as a vehicle suspension component and the yoke used as a connecting piece of the vehicle suspension. In addition, forging machines capable of applying high loads are expensive, resulting in high manufacturing costs.

In the present invention, since pressure is applied to the side surface of the forged material, the plastic flow of the material proceeds longitudinally from the portion with a smaller projected area, thereby enhancing the strength of this portion. When the forged product is a component having a plurality of branches, lamellar metal flow occurs along the contours of the branches, thereby increasing the strength of the branches.

The present invention provides a closed forging method in which pressure is applied to a side surface of a forged material. When the forging material is a cut piece (section) cut from a round bar material, in forging the pressure is applied not to the cut surface of the piece but to the surface perpendicular to the cut surface of the piece . In particular, pressure is exerted on the side surfaces of the cut workpiece.

In a forging method in which pressure is applied to the cut surface of a cut workpiece obtained from a round bar material, in the process of producing an upper arm or a lower arm as a vehicle suspension part having branches by plastic flow of the workpiece (forged material) In the process of preforming or a yoke as a link for a vehicle suspension, the edge where the cut surface intersects the outer peripheral surface (side surface) of the workpiece becomes a branch of the forged product. In this case, since the flow rate and direction of the plastic flow of the forged material are different in each part of the cut surface and the outer peripheral surface of the material, forging defects such as overlapping due to the above-mentioned edges will be in the forged product. The branch surface is generated. As a result, the forged product may break at the portion where the forging defect occurs, so that the product cannot be a good quality product.

The present invention employs, as a forging material, a cylindrical cast ingot having an upper surface, a lower surface and a side surface, and having no convex portion, on which pressure is applied. Therefore, since the above-mentioned edge falls on the peripheral contour of the forged product due to the plastic flow of the material, forging defects such as overlapping are prevented from being generated in the branches of the forged product. In addition, since the ratio of the lateral length of the projected plane of the forged material in the direction perpendicular to the direction of pressure application to the length of the material measured in the direction of pressure application is equal to or less than 1, the forged material in the direction perpendicular to the direction of pressure application The projected area in the direction becomes smaller, and the forging load that needs to be applied can be reduced.

When pressure is applied to the outer peripheral surface (i.e., the surface perpendicular to the cut surface) of a cut workpiece obtained from a round bar material as a cylindrical forging material, the above-mentioned edge falls on the peripheral contour of the forged product due to plastic flow of the material On the other hand, forging defects such as overlapping are prevented from being generated in the branch of the forged product, which is a preferable case. Also preferably, since the ratio of the thickness of the cut workpiece to the diameter of the cut workpiece is equal to or less than 1, the projected area of the cut workpiece (forged material) in the direction perpendicular to the direction of pressing becomes smaller, and the applied forging load can be reduced.

In the method of the present invention, the profile of the upper surface and/or the lower surface of the forged material preferably has no convex portion and is in a smooth shape. Preferably, its profile is circular, elliptical or smoothly extending polygonal, as these shapes prevent forging defects such as overlapping.

From the standpoint of cost and machinability, the forging material used in the present invention is preferably a cylindrically cut workpiece obtained from round bar material such that the ratio of the thickness (Tmm) of the workpiece to the diameter (Rmm) of the workpiece (T/R) is equal to or less than 1 (preferably equal to or less than (π/4), more preferably equal to or less than 0.5).

In the method of the present invention, the forged material may be a metallic material. Examples of metallic materials include aluminum, iron, magnesium, and alloys mainly containing such a metal. Examples of aluminum alloys include Al-Mg-Si alloys, Al-Cu alloys, and Al-Si alloys. Examples of Al-Mg-Si alloys include JIS 6061 alloy and SU 610 alloy. Examples of Al-Cu alloys include JIS 2024 alloy and JIS 2014 alloy. An example of Al-Si alloy is JIS 4032 alloy.

The wrought material used in the present invention can be produced by any conventional method, such as continuous casting, extrusion or rolling. From the standpoint of low cost, a continuously cast round bar material of aluminum or aluminum alloy is preferred. More preferred is an aluminum alloy round bar material (such as SHOTIC material) continuously cast by an air pressure hot hat (heat cap) casting method because the material exhibits excellent internal integrity (compactness) and has a fine grain , no anisotropy due to plastic working. That is, when the round rod material (a forging material) of aluminum alloy is used in the forging method of the present invention, the material flows uniformly (consistently) in lamellar plasticity in each branch of the forged product, so that the not filled such The forging defects will not be produced, and the reason for improving the mechanical strength of the product.

In the forging method of the present invention, preferably, the volume (Vmm ³ ) of the forged product, the thickness (Tmm) of the round bar material, the longitudinal length (Lmm) of the projected plane of the forged product in a direction perpendicular to the direction of pressing And the diameter (Rmm) of the round rod material satisfies the following relationship:

$<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\sqrt{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; T\&pi;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; .</span>$

when $R=2\&times;\sqrt{(V/\mathrm{T\&pi;})}<(1/3)L$ (R: diameter of the cut workpiece obtained from the round bar material), due to the plastic flow of the material in the branches of the forged product in a single forging step, it is necessary to apply a diameter greater than the maximum obtained from a press. The forging of the load loads the workpiece (forged material), and thus requires a plurality of forging steps. In addition, due to insufficient applied load, underfilling may occur in the forged product, resulting in failure of manufacture of the desired forged product. In this case, the distance for the plastic flow of the forging material becomes long, and the lubricating film provided between the forging material and the die is broken, resulting in forging defects such as sticking and galling (pilling) on the forged product. Therefore, machining is required to remove forging defects. At the same time, if $L<R=2\&times;\sqrt{(V/\mathrm{T\&pi;})},$ Since the cut workpiece cannot be placed in the forging die, closed forging cannot be performed.

Regarding the round bar material (forged material) used in the present invention, preferably, the thickness (Tmm) of the round bar material is 0.8 to 1.0 times the lateral length (tmm) of the projected surface of the forged product in the direction perpendicular to the pressing direction . When the thickness of the cut workpiece obtained from round bar material is at least 0.8 × t and at most 1.0 × t, the forging material is not placed obliquely in the forging die, but the material placed in the die is stably placed in the die of. Therefore, forging defects, such as underfill, thickness deviation and overlap, will not occur in forging, which makes forged products manufactured with high quality. However, when the thickness of the cut workpiece exceeds 1.0×t, since the forging material cannot be placed in the forging die, closed forging without flash cannot be performed.

According to the closed forging method of the present invention, pressure is applied to the side surface of a cylindrical cast ingot as a forging material. In addition, the cast ingot has the same volume as the forged product, and it assumes a shape that does not contain convex corners on its upper, lower, and side surfaces. The lateral length of the projected plane of the ingot in the direction perpendicular to the direction of pressing The ratio to the length of the ingot measured in the pressing direction is 1 or less. Therefore, the load to be applied in forging can be reduced, the yield of forged products based on the forging material is high, and the mechanical strength of the forged products can be enhanced.

According to the method of the present invention, a forged preform of an upper arm or a lower arm as a vehicle suspension part can be manufactured by applying a load to a side surface of a cylindrical forging material. In addition, the load to be applied during forging can be reduced, and the yield of finished products based on the forged material is high. The forging preform of the upper arm or lower arm as a vehicle suspension component is manufactured by forging, and the forging material is plastically flowed along a plurality of branches. That is, laminar metal flow occurs along the contours of multiple branches. As a result, the mechanical strength of the branches increases.

The term "metal flow" as used herein refers to the flow of grains of a forged product produced by forging in the form of plastic (press) working. The expression "laminar metal flow occurs" means a state in which crystal grains flow uniformly along the contour of a forged product. That is, the metal flows in layers along the contour of the forged article, and the layers do not terminate at the surface of the article, or no perturbation of the layers is observed in the article. In other words, the forged article has metal flow lines along its various branches.

When using an aluminum alloy such as JIS 2014 alloy or JIS 6061 alloy, the greater the amount of plastic flow, the greater the mechanical strength. However, when the amount of plastic flow is too large, enlarged grains are produced in some forged grains. The enlarged crystal grains greatly reduce the mechanical strength. In the conventional forging method with flash, the amount of plastic flow near the parting line (separation line) is large, so that the crystal grains near the parting line become larger, resulting in a decrease in mechanical strength.

However, according to the invention, there is no parting line due to the absence of any flash. Therefore, the present forging method can suppress the growth of crystal grains compared with the conventional forging method. Thus, the present forging method is superior to the conventional forging method because no local decrease in mechanical strength occurs.

Since the preform of the upper arm or the lower arm of the vehicle suspension part produced by the forging method has no burr, no trace of cutting burr is formed on the preform, and the yield of the preform based on the forged material is high.

According to the method of the present invention, a yoke as a connecting member used in a vehicle suspension component can be manufactured by applying pressure to a side surface of a cylindrical forged material. In addition, the load that needs to be applied in forging can be reduced, and the yield of finished products based on the forged material is high. A yoke as a vehicle suspension component is produced by the forging method such that the forged material plastically flows along a plurality of branches. That is, laminar metal flow occurs along the contour of each branch. As a result, the mechanical strength of each branch increases.

Since the yoke as a vehicle suspension component produced by the forging method has no flash, no trace of flash removal is formed on the yoke, and the yield of the yoke based on the forged material is high.

A closed forging manufacturing system employing the closed forging method of the present invention will be described below.

An example of the closed forging manufacturing system will now be roughly described with reference to FIG. 10 .

In FIG. 10 , the closed forging manufacturing system includes a material cutting device 101 and a forging machine 105 . In the case of hot forging where the forged material is to be heated prior to forging, the manufacturing system preferably includes a material heating device 103 . More preferably, the manufacturing system includes a material feeding device 102, a material delivery device 104 and a forged product delivery device 106 to realize a fully automatic production system. When the forged product assumes a finished shape, a forged product heat treatment furnace 107 is preferably provided.

Material cutting equipment 101 is used to cut a continuously cast round bar into workpieces (sections), each workpiece having the same volume as a forged product. The material feeding device 102 is used to store a predetermined amount of forging material in a hopper, and then supply the material to subsequent devices. Material transfer apparatus 104 is used to transfer forging material into the die. The forging machine 105 is used to forge the forging material. The forged product conveying equipment 106 is used to unload the forged product from the forging mold through a blank (die opening) mechanism, or unload the forged product in the split mold from the forging mold, and then transmit the forged product to the downstream equipment. The material heating device 103 is used to heat the material to improve its forgeability. The forged product heat treatment furnace 107 is used for heat treatment of the forged product, including continuous solution treatment and continuous aging treatment.

The structure of the forging die of the present invention used in the forging machine will now be roughly described with reference to FIG. 11. FIG.

The forging die of the present invention includes a punch 111 , a die block 112 , a core 113 and an ejector 114 . In the case of hot forging that requires heating of the forged material before forging, for example, in the forging die or in the forging machine, it is preferable to have a lubricant spraying device for spraying lubricant to the die when required 115. The lubricant spraying device 115 may be provided separately from the forging machine, and the operation of the device may be associated with the operation of the forging machine.

The design of the mold of the present invention is such that a cylindrical casting ingot (forging material) can be placed in the space defined between the mold block, ejector and core, and pressure is applied to the cylindrical casting ingot on the side surface of the block. The cylindrical cast ingot has the same volume as that of the forged product, is shaped to have an upper surface, a lower surface and a side surface, does not have a convex portion, and has a direction perpendicular to the pressing direction of the ingot. The ratio of the lateral length of the projected surface to the length of the ingot measured in the pressing direction is equal to or less than 1.

Preferably, the die of the present invention is designed to be able to manufacture parts with multiple branches by closed-circuit forging of a cylindrical workpiece (forging material). The cylindrical workpiece may be placed in the space bounded by the die block, punch, ejector and/or core, pressure being applied to the side surfaces of the cylindrical workpiece. The cylindrical workpiece is obtained by cutting a round bar so that the ratio T/R of the thickness (Tmm) of the workpiece to the diameter (Rmm) of the workpiece is equal to or less than 1, and the volume of the workpiece and the volume of the forged product (Vmm ³ )same.

From the viewpoint of metal flow, in particular, the mold is preferably designed so that the cylindrical workpiece can be placed in the above-mentioned space so as to be in contact with the vicinity of the meeting point of the respective extending branches.

Preferably, the die of the present invention has a space bounded by the die block, punch, ejector and/or core such that the volume of the forged product (Vmm ³ ), the thickness of the round bar material (Tmm), the forged product Satisfy the relationship between the longitudinal length (Lmm) of the projected surface in the direction perpendicular to the direction of pressure application and the diameter (Rmm) of the round bar material $(1/3)\&times;L\&le;R=2\&times;\sqrt{(V/\mathrm{T\&pi;})}\&le;L.$

Preferably, the die of the present invention has a space bounded by the die block, punch, ejector and/or core such that the thickness (Tmm) of the round bar material is 0.8 to 1.0×(the forged product is perpendicular to the applied The lateral length of the projection surface in the direction of the pressure direction (tmm)).

The closed forging manufacturing system of the present invention includes a die designed so that a cylindrical cast ingot (forging material) can be placed in the space defined by the die block, punch, ejector and/or core , pressure was exerted on the side surfaces of the cylindrical cast ingot. The cylindrical cast ingot has the same volume as the wrought product, assumes a shape having an upper surface, a lower surface and a side surface, is free of lobes, and has such proportions that the ingot is The ratio of the lateral length of the projection plane in the direction of the pressing direction to the length of the ingot measured in the pressing direction is 1 or less.

Preferably, the closed forging manufacturing system of the present invention includes a die designed to manufacture a component having a plurality of branches by performing closed forging on a cylindrical workpiece (forging material). The cylindrical workpiece can be placed in the space bounded by the die block, punch, ejector and/or core such that pressure can be exerted on the side surfaces of the cylindrical workpiece. The cylindrical workpiece is obtainable by cutting a round bar material so that the ratio T/R of the thickness (Tmm) of the workpiece to the diameter (Rmm) of the workpiece is equal to or less than 1, and the volume of the workpiece and the volume of the forged product (Vmm ³ ) the same.

The forging die used in the closed forging manufacturing system of the present invention may be only one part selected from the following, that is, an integral die consisting of a die block formed by combining a die block, a die core and an ejector , and a split mold formed by combining a mold block and a plurality of mold cores arranged therein. From the viewpoint of improving the service life of the forging die, it is preferable to use a split die.

The mold of the present invention is designed so that a cylindrical casting ingot (wrought material) can be placed in the space delimited by the die block, punch, ejector and/or core and pressure can be applied to the cylindrical casting ingot on the side surface. The cylindrical cast ingot has the same volume as the wrought product, assumes a shape having an upper surface, a lower surface, and a side surface, is free of lobes, and has such proportions that the ingot is perpendicular to the applied The ratio of the lateral length of the projection plane in the direction of the pressing direction to the length of the ingot measured in the pressing direction is 1 or less. Therefore, the load applied in forging can be reduced, the yield of forged products based on the forging material is high, and the mechanical strength of the forged products can be improved.

An embodiment of the forging method of the present invention using a closed forging manufacturing system shown in FIG. 10 and a die shown in FIG. 11 will be described below.

The closed forging method of the present invention includes the steps of: cutting a continuously cast round bar into workpieces (forged materials), each workpiece having the same volume as the forged product; storing a predetermined amount of forged materials in a hopper; Each forging material supplies subsequent steps of transferring the forging material to a die; forging the transferred forging material; unloading the forged product from the die through a billet discharge mechanism; and subjecting the produced forged product to heat treatment, including continuous solid solution treatment and continuous aging treatment.

In the case of cold forging where a forged material is forged at normal temperature to produce a forged product with a simple shape, from the viewpoint of reducing the forging load and preventing sticking between the forged product and the die, it is best to perform it before forging if necessary. Phosphate surface treatment (phosphating) step for chemically coating wrought materials.

In the case of hot forging in which the forging material is heated to produce a forged product having a complex shape, from the viewpoint of reducing the forging load and preventing sticking between the forged product and the die, it is preferable to perform the following steps if necessary In any one, these steps are: preheating the forging material, lubricating the forging material with water-soluble graphite before forging, preheating the closed forging die to a predetermined temperature, and forging the forging material into the closed forging die The forged parts are sprayed with water-soluble graphite lubricant.

Referring now to FIG. 12, an example of the structure of a split die equipped with a drive mechanism used as a closed forging die will be described.

In FIG. 12 , a pair of split mold blocks 121 are arranged at a predetermined distance apart, and their front surfaces have mold portions facing each other. The rear surfaces of the pair of split mold blocks 121 are each provided with an arm 122 connected to a driving mechanism (not shown), such as a hydraulic cylinder, an electric motor, etc., through a power transmission mechanism. During forging, the pair of split die blocks 121 are moved toward each other into pressure contact to form a closed forging die.

After the forging is completed, the drive mechanism is driven in the opposite direction to open the split die block and take out a forged product.

The location where the arm 122 is disposed on the rear surface of each split mold block 121 is preferably at the rear surface where the branches meet, since then there is no unbalanced load acting on the rear surface. In the case of manufacturing products requiring precise dimensions, a forging die can be formed by setting a plurality of arms at desired positions on each split die block.

In the example shown in Figure 12, each split mold block is connected to a drive mechanism. However, it is also possible to connect a driving mechanism to one of the split die blocks while the other is fixed, so that the forging is driven.

Using split die blocks can achieve the same effect as using closed forging dies, so that forged products can be unloaded not only from above the die block, but also in the direction of opening the die block. This allows the forged product to be removed from the die block regardless of the travel out of the die block. In particular, a forged product having an undercut shape that cannot be obtained with a closed forging die can be manufactured with a split die block. The "undercut shape" means a shape that cannot be taken out even by using an ejection mechanism.

Moreover, since the split mold is divided into two mold blocks, the lubricant can be sprayed on the whole mold conveniently, and the maintenance of the mold can be improved.

The closed forging manufacturing system of the present invention employs a forging die designed to allow a cylindrical cast ingot (forging material) to be placed in a space defined by a punch, die block, ejector and/or core In the space, pressure is exerted on the side surfaces of the cylindrical casting ingot. The cylindrical cast ingot has the same volume as the wrought product, assumes a shape having an upper surface, a lower surface, and a side surface, free of lobes, and has such proportions that the ingot will The ratio of the lateral length of the projected plane in the direction of the direction to the length of the ingot measured in the pressing direction is equal to or less than 1. Therefore, the load to be applied at the time of forging can be reduced, the yield of forged products based on the forging material is high, and the mechanical strength of the forged products can be improved.

The present invention will be described in detail below with reference to examples, which are not intended to limit the present invention.

Example 1:

To manufacture the yoke 43 shown in FIG. 2 as a connecting part for vehicle suspension by forging, a cut work of JIS 6061 aluminum alloy material having the same volume as the yoke 43 is designed as a forging material in the following manner.

The volume of the yoke 43 is calculated using a CAD system programmed in a computer. According to the calculation results, the volume of the cut workpiece is designed to be 38.8cm ³ . The tolerance for the volume of the cut workpiece is determined as ±1% of the calculated volume of the yoke.

Next, the thickness (T) of the cut workpiece is designed to be 34 mm, which is 0.95 of the lateral length (t) of the projected surface of the forged product in the direction perpendicular to the direction of pressing (represented by the reference letter A in Figure 13). times, the transverse length is indicated by the reference letter B (see Figure 14). According to the volume and thickness of the cut workpiece, the diameter of the cut workpiece is determined by the following equation:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\sqrt{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 38,800</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 34</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}$

Here, R satisfies: (1/3)×(longitudinal length L indicated by reference letter C in FIG. 14)≦R≦(longitudinal length L indicated by reference letter C in FIG. 14).

In addition, in Fig. 13, reference numeral 131 refers to a punch, reference numeral 133 refers to an ejector, reference numeral 134 refers to an ejector, and reference numeral 135 refers to a yoke as a forged product.

Based on the above design, a continuously cast round bar of JIS 6061 aluminum alloy with a diameter of 38.1 mm was cut into 10 disc-shaped workpieces, each with a diameter of 38.1 mm, a thickness of 34 mm, and a volume of 38.8 cm ³ . These 10 The average weight of each cut workpiece was 104.8 grams.

Each disc-shaped cut workpiece 151 was subjected to a conventional known bond treatment and then placed in a forging die as shown in FIG. 15 . Next, cold forging is performed by applying a load to the outer peripheral surface of the cut workpiece with a punch at room temperature. A 400-ton press equipment (product of AIDA) was used as forging equipment. The average forging load is 1,372kN. The average weight of these 10 forged articles was 104 grams. The average longitudinal length L (indicated as C in FIG. 14 ) of the projected surface of the forged product in the direction perpendicular to the pressing direction was 51 mm.

In the forging process in the above case, no blocking or the like was found in the forged product, and problems such as a sharp increase in the forging load did not occur.

In order to check the quality of the forged product, the appearance of the product was visually evaluated. As a result, the percentage of occurrence of forging defects such as sticking and overlapping was 0%. That is, (number of samples with forging defects/total number of samples)=(0/10). Since there is no adhesion phenomenon, the plastic flow resistance of the forged material does not increase, and the forging load does not increase sharply. It is expected that since the forging load does not increase sharply, the service life of the forging die can be expected to be extended.

The yield is about 99% based on the wrought material by weight of the forged article.

Comparison example 1:

The yoke 43 shown in FIG. 2 is a connecting part for the suspension of a vehicle, and is manufactured by conventional hot forging with flashing.

To prepare a forging material, a JIS 6061 continuous casting round bar with a diameter of 40.6 mm was cut into ten disk-shaped workpieces 161 each having a diameter of 40.6 mm, a thickness of 50 mm, and a volume of 65 cm ³ . The average weight of the 10 cut pieces was 175 grams.

The surface of each disc-cut workpiece 161 was subjected to a conventional known coating treatment with a water-soluble graphite lubricant, and then the workpiece was placed in a forging die as shown in FIG. 16 . Next, for hot forging with flash, the forging material is heated to 420°C, the mold is preheated to 200°C, and a water-soluble graphite lubricant is sprayed onto the forging mold. Then, hot forging is performed by applying a load to the outer peripheral surface of the cut workpiece using a punch. A 400-ton press equipment (product of AIDA) was used as forging equipment. The average forging load is 2,940kN. After forging is completed, the resulting flash is cut off with a trimming die, thereby obtaining a forged product. The average weight of the 10 forged articles was 104 grams. The yield based on the wrought material is about 59% by weight of the wrought product. Strength test and metal flow observation:

The forged articles produced in Example 1 and Comparative Example 1 were subjected to heat treatment including solution treatment at 510° C. for 6 hours and aging treatment at 170° C. for 6 hours. Then, a tensile specimen ASTM-R5 with a width of 2.87 mm and a marked length (gauge length) of 11.5 mm was obtained by cutting at the position corresponding to the P position shown in Figure 2 of each forged product, as shown in Figure 17 to evaluate the mechanical properties of the samples. Tensile tests were performed using Autograph (material tester) (product of Shimadzu Corporation) under the condition of a tensile load of 5 kN. Ten test pieces (of each forged product) were subjected to the tensile test.

The data of the mechanical properties obtained from the tensile test are as follows, Table 1 shows the data of the sample of Example 1, and Table 2 shows the data of the sample of Comparative Example 1.

Table 1 sample Tensile strength (N/mm ² ) 0.2% yield stress (N/mm ² ) Elongation (%) 1 328.33 307.01 16.5 2 330.43 304.32 18.9 3 332.91 302.95 17.6 4 332.91 304.55 18.7 5 329.67 299.93 17.5 6 332.91 304.55 18.3 7 330.62 299.41 18.0 8 331.19 300.00 17.4 9 330.22 317.11 19.2 10 329.08 297.65 19.3 average value 330.83 303.75 18.1

Table 2 sample Tensile strength (N/mm ² ) 0.2% yield stress (N/mm ² ) Elongation (%) 1 305.10 277.60 16.8 2 305.29 275.09 17.7 3 300.68 273.92 18.5 4 301.23 273.60 17.6 5 310.12 283.01 19.5 6 309.55 280.18 19.5 7 301.09 271.31 18.6 8 304.91 276.30 7.5 9 306.82 279.16 20.3 10 306.05 278.39 19.2 average value 305.08 276.86 18.1

From the above Tables 1 and 2, it can be clearly seen that the tensile strength and 0.2% yield stress of the forged products manufactured by the closed forging method of the present invention are higher than those of the forged products manufactured by the conventional hot forging method accompanied by burrs. The product is about 10% higher. Accordingly, the forged articles of the present invention exhibit improved mechanical properties.

Next, in order to observe the metal flow in the branch of each forged product, a sample was cut from the forged product for observing the metal flow. The surface of the sample to be observed for metal flow was polished with corundum sandpaper, and then the sample was etched, wherein the sample was immersed in 20% sodium hydroxide solution for 30 seconds. To assess metal flow, the macrostructure (structure) of the samples obtained was visually observed.

As a result, in the forged product produced by the method of the present invention, forging defects such as overlapping were not observed because the angled side where the cut surface of the forged material and its peripheral surface intersect fell on the peripheral contour of the forged product. Moreover, it was also observed that the metal flowed uniformly along the multiple branches of the forged article, the layers of metal flow did not end (terminate) at the surface of the article, and disturbance of the layers was not observed. This result shows that the forged material undergoes lamellar plastic flow along the branches of the forged product. On the contrary, under the above conditions, the macrostructure of forged products produced by conventional hot forging with burrs was observed, and it was found that the metal flow did not occur along multiple branches of the forged products.

Because the trimming step called "flash removal step" is not performed in the process of obtaining forged products by the closed forging method of the present invention, the obtained forged products have no traces of flash removal, which means that based on the forging material The yield of products is high. On the contrary, when the forged product is produced by the conventional hot forging method with burr, since the obtained forged product must undergo a trimming step to remove the burr, the product has traces of burr removal.

Example 2:

In order to manufacture the yoke shown in FIG. 18 as a connecting member for vehicle suspension, a cut work of JIS 6061 aluminum alloy having the same volume as the yoke was designed as a forging material in the following manner.

The volume of the yoke is calculated with a CAD system program programmed in the computer. According to the calculation results, the volume of the cut workpiece is designed to be 84.0cm ³ . The tolerance for the volume of the cut workpiece is determined as ±1% of the calculated volume of the yoke.

Next, the thickness of the cut workpiece is designed to be 30 mm, which is 0.95 times the lateral length (t) of the projected plane of the forged product in the direction perpendicular to the direction of pressure D shown in Figure 19, which is shown in Figure 20 Indicated by the reference letter E. According to the volume and thickness of the cut workpiece, the diameter (R) of the cut workpiece is determined by the following equation:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\sqrt{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 84,000</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 30</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; .</span>$

Here, R does not satisfy the condition: (1/3) x (longitudinal length (L) represented by reference letter F in FIG. 20)≤R≤(longitudinal length (L) represented by reference letter F in FIG. 20) , but satisfy the condition: R≦(1/3)×(the longitudinal length (L) indicated by the reference letter F in FIG. 20).

In addition, in FIG. 19, reference numeral 191 designates a punch, numeral 192 designates a die block, numeral 193 designates an ejector, numeral 194 designates a blank ejector and numeral 195 designates a forged product. yoke.

On the basis of the above design, a continuously cast round bar of JIS 6061 aluminum with a diameter of 59.7 mm was cut into 10 disc-shaped workpieces, each with a diameter of 59.7 mm, a thickness of 30 mm, and a volume of 84.0 cm ³ . The average weight of these 10 workpieces was 227 grams.

Each disk-shaped cut workpiece 211 was conventionally coated with a phosphate lubricant (bonde lubricant) and then placed in the forging die shown in FIG. 21 . Next, cold forging is performed by applying a load on the outer peripheral surface of the cut workpiece with a punch at room temperature. An 800-ton press equipment (product of Komatsu Seisakusho Co., Ltd.) was used as the forging equipment. The average weight of the obtained forged product was 226.5 g. The average longitudinal length (L) of the projected plane of the forged product in the direction perpendicular to the pressing direction was 200 mm, indicated by reference letter F in FIG. 20 .

Observation of the macrostructure of the forged product confirmed that: the corner edge where the cut surface of the forged material meets its peripheral surface follows the peripheral contour of the forged product, the metal flow occurs along multiple branches of the forged product, the layers of the forged material Shaped plastic flow occurs along the branches of forged products.

When forging is performed under the above conditions, since the plastic flow of the forged material occurs over a long distance until the material reaches the point G shown in FIG. In the part H shown in Fig. 19 . The percentage of occurrence of adhesions was 80%. That is, (number of samples with adhesion/total number of samples)=(8/10). The sticking due to the breakage of the lubricating die between the forged material and the die is removed from the surface of the forged product.

Example 3:

The thickness of the disc-shaped cut-out workpiece obtained from round bar material is designed to be 25 mm, ie 0.7 of the transverse length indicated by the reference letter B in FIG. 14 . The diameter R of the cut workpiece is determined to be 44mm by the following formula:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\sqrt{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 38,800</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 25</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; .</span>$

Here, R satisfies the condition: R≦(longitudinal length (L) denoted by reference letter C in FIG. 14).

Forging was performed with this cut workpiece in a similar manner to Example 1. As a result, since the cut workpiece (forging material) was unstable and tilted in the forging die during forging, the percentage of forging defects such as underfilling or overlapping occurred in the resulting forged product at a rate of 50%.

Example 4:

In order to manufacture the preform shown in Figure 6 as the upper arm of the vehicle suspension part, a cut workpiece (forged material) of JIS 6061 aluminum alloy having the same volume as the preform is designed as follows:

The volume of the upper arm preform is calculated with a CAD system program programmed in a computer. The volume of the cut workpiece based on the calculation results is designed to be 862 cm ³ . The tolerance for the volume of the cut workpiece is determined to be ±1% of the calculated preform volume.

Next, the thickness of the cut workpiece is designed to be 28 mm, which is 0.95 times the lateral length (t) of the projected plane of the forged product in the direction perpendicular to the pressing direction I shown in Figure 1, which is shown in Figure 22 is indicated by the reference letter J. According to the volume and thickness of the cut workpiece, the diameter (R) of the cut workpiece is determined by the following formula:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\sqrt{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 862</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 000</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 28</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; .</span>$

Here, R satisfies the condition: (1/3)×(longitudinal length (L) indicated by reference letter K in FIG. 22)≦R≦(longitudinal length (L) indicated by reference letter F in FIG. 22).

According to the above design, a continuous casting billet of JIS 6061 aluminum alloy with a diameter of 198mm is cut into 10 disc-shaped workpieces, each workpiece has a diameter of 198mm, a thickness of 28mm, and a volume of 862cm ³ . The average weight of the 10 cut pieces was 2,330 grams.

In addition, in FIG. 1, reference numeral 11 designates a punch, numeral 12 designates a die block, numeral 13 designates an ejector, numeral 14 designates a blank, and numeral 15 designates a forged preform of an upper arm.

The surface of each disc-shaped cut workpiece 231 was subjected to conventionally known coating treatment with a water-soluble graphite lubricant, and a generally known water-soluble graphite lubricant was sprayed onto the forging die. Next, the cut workpiece is placed in a die as shown in FIG. 23, and a load is applied to the outer peripheral surface of the cut workpiece with a punch to perform hot forging. A 3,000-ton press equipment (product of Sumitomo Heavy Industries. Ltd.) was used as the forging equipment. Hot forging is performed at a material heating temperature of 500°C and a mold temperature of 200°C. The average forging load is 6,370kN. The average weight of the obtained forged product was 2,328 grams. The average longitudinal length (L) of the projected plane of the forged product in the direction perpendicular to the pressing direction - indicated by reference letter K in Fig. 22 - was 392 mm.

The yield based on the wrought material is about 99% by weight of the wrought product.

Since the laminar plastic flow of the forged material occurs along multiple branches of the forged product, the mechanical strength of the product is improved. In addition, since the forged product is manufactured by the closed-type forging method of the present invention, the forged product has no traces of cutting flash, and the output of the product is high.

A preform is used to produce an upper arm 54 as shown in FIG. 5 by conventional hot forging with flashing. Two forging steps were performed under the conditions of a material heating temperature of 500°C and a mold temperature of 150°C. The forging load of the first forging step was 22,540 kN, and the forging load of the second forging step was 17,640 kN. A trimming die is used to remove flash from the forged body, and the resulting forged body is shaped to obtain a forged product. In this case, the weight of the upper arm (forged product) shown in Fig. 5 is 1,650 grams, while the average weight of the cut disc is 2,330 grams. Thus, the yield on a material basis was 71% by weight of the article.

Comparison example 2:

Fig. 7 shows the preform of the upper arm of Example 4 manufactured by conventional hot forging with flashing. Hot forging was carried out under the condition that the material heating temperature was 500°C and the mold temperature was 180°C. A cut work (forged material) having a diameter of 80 mm, a length of 360 mm, a volume of 1,810 cm ³ and a weight of 4,900 g was obtained from a continuously cast round bar of JIS 6061 aluminum alloy having a diameter of 80 mm. In this hot forging, the forging load was 49,000 kN. After the forging is completed, a trimming die is used to cut off the flash to obtain a forged body, and its shape is adjusted to obtain a forged product. In this forging process, two upper arm preforms are manufactured from one piece of forging material. The average weight of the two forged articles was 1,960 grams. The forging load required to manufacture one preform was calculated to be half of the above-mentioned forging load, and was determined to be approximately 24,500 kN. The yield based on the forged material is 80% by weight of the forged product.

A preform is used to produce an upper arm 54 as shown in FIG. 7 by conventional hot forging with flashing. Two forging steps were performed under the conditions of a material heating temperature of 500°C and a mold temperature of 180°C. The forging load in the first forging step was 14,700 kN, and the forging load in the second forging step was 14,700 kN. A trimming die is used to remove flash from the forged body whose shape is adjusted to obtain a forged product. In this case, the weight of each of the two upper arms 74 (forged products) shown in FIG. 7 is 1,650 grams, and the weight of the cut work 71 is 4,900 grams. Thus, the yield on a material basis was 67% by weight of the article.

Example 5:

In order to manufacture the upper arm shown in FIG. 24 as a vehicle suspension component, the forged preform shown in FIG. 25 of the upper arm is manufactured. The cut workpiece (forged material) of JIS 6061 aluminum alloy having the same volume as the forged preform is designed as follows:

The volume of the upper arm preform is calculated using a CAD system programmed in a computer. According to the calculation results, the volume of the cut workpiece is designed to be 595cm ³ . The tolerance for the cut workpiece volume is determined as ±1% of the calculated preform volume.

Next, the thickness of the cut workpiece is designed to be 30 mm, which is the transverse length (t) of the projected plane of the forged product represented by the reference letter N in FIG. 27 in the direction perpendicular to the pressing direction M shown in FIG. 26 0.95 times. According to the volume and thickness of the cut workpiece, the diameter (R) of the cut workpiece is determined by the following formula:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\sqrt{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 595,000</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 30</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; .</span>$

Here, R satisfies the condition: (1/3) × (the longitudinal length (L) represented by the reference letter O in FIG. 27) ≤ R ≤ (the longitudinal length represented by the reference letter O in FIG. 27 ( L))

In addition, in FIG. 26, reference numeral 261 designates a punch, numeral 262 designates a die block, numeral 263 designates an ejector, numeral 264 designates a blank ejector, and numeral 265 designates a forging preform of the upper arm. type pieces.

According to the above design, a continuously cast billet of JIS 6061 aluminum alloy with a diameter of 167 mm was cut into 10 disc-shaped workpieces, each of which had a diameter of 167 mm, a thickness of 30 mm, and a volume of 595 cm ³ . The average weight of the 10 workpieces was 1,607 grams.

The surface of each disk-shaped cut workpiece 281 is subjected to a generally known coating treatment with a water-soluble graphite lubricant, and a generally known water-soluble graphite lubricant is sprayed on the forging die. Next, as shown in FIG. 28, the cut workpiece is placed in a die, and hot forging is performed by applying a load to the outer peripheral surface of the cut workpiece with a punch. A 3,000-ton press facility (product of Sumitomo Heavy Industries, Ltd.) was used as a forging facility. The hot forging is carried out under the condition that the material heating temperature is 500°C and the die temperature is 200°C. The average forging load is 4,900kN.

The average weight of the obtained forged product was 1,800 grams. The average longitudinal length (L) of the projected plane of the forged product in the direction perpendicular to the pressing direction was 310 mm, indicated by O in FIG. 27 .

The yield based on the forged material was 99% by weight of the forged product.

Since the laminar plastic flow of the forged material occurs along multiple branches of the forged product, the mechanical strength of the product is improved. In addition, since the forged product is manufactured by the closed forging method of the present invention, the forged product has no trace of cutting flash, and the yield of the product is high.

Example 6:

Forging was performed in the same manner under the same conditions as Example 4 except that the aluminum alloy variety of the forging material was changed.

In order to manufacture the preform of the upper arm as a vehicle suspension component shown in Fig. 6, a continuously cast SU 610 aluminum alloy round bar was cut into a cut workpiece (forged material) with the same volume as the preform. The aluminum alloy consists of 0.8 to 1.2% by weight of magnesium (Mg), 0.7 to 1.0% by weight of silicon (Si), 0.3 to 0.6% by weight of copper (Cu), 0.14 to 0.3% by weight of chromium (Cr), 0.14 to 0.1% by weight 0.3% by weight of manganese (Mg) and the balance aluminum (Al) and unavoidable impurities.

Comparison example 3:

The same forged alloy variety as in Example 6 was forged under the same forging conditions as in Comparative Example 2.

The strength test and metal flow observations are as follows:

The forged articles produced in Example 6 and Comparative Example 3 were subjected to heat treatment including solution treatment at 530° C. for 6 hours and aging treatment at 180° C. for 6 hours. Then, a tensile test piece ASTM-R3 with a marked diameter of 6.4 mm and a marked length of 25.4 mm as shown in Figure 17 was cut from each forged product corresponding to the position Q shown in Figure 6, and the test piece The mechanical properties were evaluated. A tensile test was performed under the condition of a tensile load of 20 kN using Autograph (product of Shimadzu Corporation). Three test pieces (of each forged article) were subjected to tensile testing. The mechanical properties data obtained from the tensile tests are shown in Table 3 below.

table 3 Specimen Tensile strength (N/mm ² ) 2% yield stress (N/mm ² ) Elongation (%) Example 6 1 385 333 15.7 2 385 331 15.9 3 387 333 16.6 average value 386 332 16.1 Comparative example 3 1 358 325 8.4 2 356 323 12.2 3 362 330 10.4 average value 359 326 10.3

From the above Table 3, it can be clearly seen that the tensile strength, 0.2% yield stress and elongation of the forged product produced by the closed forging method of the present invention are higher than those of the forged product produced by the conventional hot forging method accompanied by burrs. height of. The wrought articles of the present invention therefore exhibit improved mechanical properties.

Next, in order to observe metal flow in the branch of each forged product and grains near the parting line, an observation sample was cut from the forged product. The surface of the sample to be observed is polished with corundum sandpaper, and then the sample is soaked in 20% sodium hydroxide solution for 30 seconds for etching treatment. The macrostructure of the resulting samples was visually observed for the assessment of metal flow and grains near the parting line. As a result, in the forged product produced by the method of the present invention, no forging defect such as overlap is observed because the angled side where the cut surface of the forged material meets its outer peripheral surface falls on the peripheral contour of the forged product. Furthermore, the metal was observed to flow uniformly along the multiple branches of the forged article, the layer in which the metal flowed did not end at the article surface, and no perturbation of the layer was observed. This result shows that the laminar plastic flow of the forged material occurs along the branches of the forged product. Also, since the forged product has no parting line, no enlarged grains were observed at the end of the forged product.

In contrast, observing the macrostructure of forged products manufactured by conventional hot forging with flash under the above conditions, it was found that metal flow did not occur along multiple branches of the forged product. In addition, enlarged grains were observed near the parting line at the end of the forged product.

Example 7:

Forging was performed under the same conditions as in Example 6, except that a split die block 121 with a driving mechanism shown in FIG. 12 was used as a forging die.

One of the mold blocks is mechanically driven and the other is fixed. The die block is closed during forging to drive the punch, and the die block is opened when the forging punch stops at the raised end of the forging machine.

Forging under these conditions did not cause any trouble, such as a sharp increase in forging load, including sticking of forged products.

Industrial applicability:

According to the closed forging method of the present invention, a cylindrical cast ingot having the same volume as that of the forged product is used as the forging material, and the presented shape has an upper surface, a lower surface and a The side surface, without the convex corner portion, on which pressure is applied to the side surface of the cylindrical forging material, has a shape having such a ratio that the lateral length of the projected surface of the ingot in the direction perpendicular to the direction of pressing is equal to the The ratio of the lengths of the ingot measured in the pressing direction is 1 or less. Therefore, the mechanical properties of the forged product are enhanced due to the laminar plastic flow of the forged material occurring along multiple branches of the forged product. In addition, the forged product does not have traces of cutting burrs, and the yield of products based on the forged material is improved.

In the yoke of the present invention as a connecting part for a vehicle suspension, laminar plastic flow of forged material occurs along a plurality of branches of the yoke. Thus, the yoke exhibits improved mechanical properties. In addition, the yoke has no traces of trimming, and the yield of the yoke based on forged material is high.

In the forged preform of the present invention as an upper or lower arm of a vehicle suspension component, laminar plastic flow of forged material occurs along a plurality of branches of the preform. Thus, the preform exhibits improved mechanical properties. In addition, the preform has no trace of cutting flash, and the yield of the preform based on the forged material is high.

The die of the present invention is designed so that a cylindrical casting ingot (forging material) can be placed in the space bounded by the punch, die block, ejector and/or core, or placed in the space defined by the punch and equipped with a drive. In the space defined by the mold blocks of the mechanism, pressure is exerted on the side surfaces of the cylindrical casting ingot. The volume of the cylindrical cast ingot is the same as that of the wrought product, it assumes a shape having an upper surface, a lower surface and a side surface, no convex portion, and the ingot is oriented in a direction perpendicular to the pressing direction The ratio of the transverse length of the projected surface of the ingot to the length of the ingot measured in the pressing direction is equal to or less than 1. Therefore, the load to be applied in forging is reduced, the yield of forged products based on the forged material is high, and the mechanical strength of forged products can be improved.

The forging die used in the closed forging manufacturing system of the present invention is designed so that the cylindrical casting ingot (forging material) can be placed in the space defined by the punch, die block, ejector and/or core, or placed In the space delimited by the punch and the die block equipped with a drive mechanism, pressure is exerted on the side surfaces of the cylindrical casting ingot. The cylindrical cast ingot has the same volume as the forged product, assumes a shape having an upper surface, a lower surface and a side surface, does not contain convex corner portions, and the ingot is oriented in a direction perpendicular to the pressing direction The ratio of the transverse length of the projected surface of the ingot to the length of the ingot measured in the pressing direction is equal to or less than 1. Therefore, the load to be applied in forging is reduced, the yield of forged products based on the forged material is high, and the mechanical strength of the forged products can be improved.

Claims (16)

1. closed-die forging method that is used to make forged article, comprise: prepare a kind of cylinder casting ingot bar as forged material, this ingot bar has the identical volume of volume (V) with forged article, and being shaped as of presenting has a upper surface, a lower surface and a side surface, and do not have the salient angle part; Exert pressure with side surface to described forged material; Wherein this shape has a kind of like this ratio: this forged material is equal to or less than 1 at the ratio of the length that records perpendicular to the lateral length on the perspective plane on the direction of direction of exerting pressure and forged material on direction of exerting pressure.

2. according to a kind of closed-die forging method of claim 1, it is characterized in that, this forged material is the cylindrical work that obtains from the cutting of a kind of pole material, makes the ratio (T/R) of thickness (T) and the diameter (R) of this forged material of this forged material for being equal to or less than 1.

3. according to a kind of closed-die forging method of claim 1 or 2, it is characterized in that the diameter (R) of the thickness (T) of the volume of this forged article (V), forged material, the longitudinal length (L) on the perspective plane of forged article on direction of exerting pressure and forged material satisfies relational expression:

$(1/3)\&times;L\&le;R=2\&times;\sqrt{(V/\mathrm{T\&pi;})}\&le;L.$

4. according to a kind of closed-die forging method any in the claim 1 to 3, it is characterized in that the thickness of forged material is the lateral length (t) that 0.8-1.0 multiply by the perspective plane of forged article on direction of exerting pressure.

5. a kind of closed-die forging method any according to claim 1 to 4 is characterized in that this forged material is an aluminum or aluminum alloy.

6. a kind of closed-die forging method any according to claim 1 to 5 is characterized in that this forged article is the parts with a plurality of branches.

7. according to a kind of closed-die forging method of claim 6, it is characterized in that these parts are as the upper arm of vehicle hanging parts or the preform of underarm.

8. according to a kind of closed-die forging method of claim 6, it is characterized in that these parts are as the yoke that is used for the connector of vehicle hanging.

9. one kind as the upper arm of vehicle hanging parts or the preform of underarm, and this preform utilization having a plurality of branches, and has the metal flow moving-wire along each branch according to any one the closed-die forging method manufacturing of claim 1 to 6.

10. one kind as the upper arm of vehicle hanging parts or the preform of underarm, and this preform utilizes according to any one the closed-die forging method of claim 1 to 6 and makes, and the vestige that does not have overlap to remove.

11. a conduct is used for the yoke of the connector of vehicle hanging, this yoke utilization having a plurality of branches, and has the metal flow moving-wire along each branch according to any one the closed-die forging method manufacturing of claim 1 to 6.

12. a conduct is used for the yoke of the connector of vehicle hanging, this yoke utilizes according to any one the closed-die forging method of claim 1 to 6 and makes, and the vestige that does not have overlap to remove.

13. a forging mold that is used for according to any one the closed-die forging method of claim 1 to 8 comprises a drift, mould piece and an ejection device.

14. a closed-die forging manufacturing system comprises equipment and a forging machine of a cutting material, wherein this forging machine comprises the forging mold according to claim 13.

15. a forging mold that is used for according to any one the closed-die forging method of claim 1 to 8 comprises a drift and the mould piece that is equipped with driving mechanism.

16. a closed-die forging manufacturing system comprises equipment and a forging machine of a cutting material, wherein this forging machine comprises the forging mold according to claim 15.

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