Forging die and manufacturing method for aluminum alloy forgings

Abstract

To provide a forging die enabling further improvement in durability.SOLUTION: A pair of forging dies 6, 7 has a die cavity 8 reflecting a shape of a forged article between surfaces facing each other, and a flash land 9 located outside the die cavity 8. The flash land 9 is located on a surface side of one die 6 facing the other die 7, and includes, in order from the die cavity 8 side: a first flat surface part 9a parallel to the surface facing the other die 7; a first slope part 9b inclining toward a direction separating from the surface facing the other die 7; a second flat surface part 9c parallel to the surface facing the other die 7; and a second slope part 9d inclining toward the direction separating from the surface facing the other die 7.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a forging die and a method for manufacturing an aluminum alloy forged product. [Background technology]

[0002] In recent years, aluminum alloys have been increasingly used as structural components for various products, taking advantage of their light weight. For example, while high-tensile steel has traditionally been used for automobile suspension and bumper parts, high-strength aluminum alloys have recently come into use.

[0003] Furthermore, while iron-based materials have been used exclusively for automobile parts, particularly suspension parts, in recent years, aluminum or aluminum alloy materials have increasingly been used instead, primarily for the purpose of reducing weight.

[0004] For example, metal arm parts with ball joints or rubber bushings at their ends are used as suspension parts for automobiles, and aluminum alloy forgings are used for these metal arm parts to achieve both light weight and strength.

[0005] Furthermore, in flash removal forging, in which excess molding material (so-called burrs) is forced out from the gap between a pair of dies during forging, a forging die is used that has, on the surface of one of the pair of dies that faces the other, a die engraved portion that reflects the shape of the forged product, and a flash land located outside the die engraved portion through which burrs of molding material that have protruded from the die engraved portion can flow (see, for example, Patent Documents 1 and 2 below). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-219544 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-260051 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, in the forging dies used in the above-mentioned flash removal forging, if a large stress is applied to the dies during forging, cracks will occur in the dies. Therefore, it is required to reduce the stress applied to the dies during forging and to extend the life of the dies.

[0008] However, in conventional forging dies, during the finish forming process after rough forming, the flash land of one of the dies deforms toward the outside of the engraved portion during forging, generating high stress at the corner of the engraved portion on the flash land side. On the other hand, if the width of the flash land is made large, the contact area with the forming material increases, increasing the forging load and requiring a forging press with a higher load.

[0009] In the forging die described in Patent Document 1, the flow of the molding material is controlled by forming minute irregularities on the flash land. However, this does not reduce the deformation of the flash land, nor does it improve the life (durability) of the die.

[0010] On the other hand, in the forging die described in Patent Document 2, grooves are provided in the upper die to reduce the contact area between the die and the forming material, thereby reducing the forging load and improving the life (durability) of the die. However, this method imparts a shape corresponding to the grooves in the die to the forged product, which leads to an increase in the weight of the forged product or an increase in costs due to post-processing.

[0011] The present invention has been made in view of the above technical background, and aims to provide a forging die that enables further improvement in durability, and a method for manufacturing aluminum alloy forgings that enables the accurate production of aluminum alloy forgings by using such a forging die. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides the following means. [1] A forging die having a pair of dies that are butted against each other and used when forging a forged product of a predetermined shape while pressing a molding material between the pair of dies, The pair of dies have, between their opposing surfaces, a die-engraved portion that reflects the shape of the forged product, and a flash land that is located outside the die-engraved portion and through which flash of molding material that has protruded from the die-engraved portion flows, The flash land is located on a surface of one of the pair of dies that faces the other die, and comprises, in order from the die-sinking portion side, a first flat surface portion that is parallel to the surface that faces the other die, a first inclined surface portion that slopes in a direction away from the surface that faces the other die, a second flat surface portion that is parallel to the surface that faces the other die, and a second inclined surface portion that slopes in a direction away from the surface that faces the other die. a third flat surface portion located on a surface of the other mold facing the one mold and parallel to the first flat surface portion; And in a cross section along the direction in which the pair of dies are butted together and along the direction in which the burr of one of the dies flows, In an XY coordinate system in which the boundary between the first flat surface portion and the first inclined surface portion is the origin, the direction in which the burr flows is the X axis, and the direction toward one of the dies is the Y axis, when the length between the first flat surface portions on both sides of the die-sinking portion is W and the thickness of the burr at the flash land is H, The cross-sectional shape does not contact the curve expressed by the following formula (1): A forging die characterized by:

number

number

[0023] Using the forging die according to any one of the above items, A method for manufacturing an aluminum alloy forging, comprising forging the aluminum alloy material, which is the molding material, between the pair of dies while applying pressure to form an aluminum alloy forging of a predetermined shape. [ 5 The forging die is used for finish forming after rough forming. 4

[0023] A method for producing an aluminum alloy forged product according to the above. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a forging die that enables further improvement in durability, and a method for manufacturing aluminum alloy forgings that enables aluminum alloy forgings to be manufactured with high precision by using such a forging die. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a cross-sectional view showing the configuration of a forging die for rough forming. [Figure 2] FIG. 2 is a cross-sectional view showing the configuration of a forging die for finish forming. [Figure 3] 3 is an enlarged cross-sectional view of a main portion of one of the forging dies that constitute the forging die shown in FIG. 2. FIG. [Figure 4] FIG. 2 is a cross-sectional view showing a state during forging of a molding material using the forging die shown in FIG. [Figure 5] 3 is a cross-sectional view showing a state during forging of a molding material using the forging die shown in FIG. 2. FIG. [Figure 6] FIG. 3 is a cross-sectional view illustrating the shape of one of the molds shown in FIG. 2. [Figure 7] FIG. 2 is a cross-sectional view showing the shape of one mold of Example 1. [Figure 8] 1 is a cross-sectional view showing the formation of one mold of Comparative Example 1. FIG. [Figure 9] 1 is a graph showing the results of measuring the stress applied to the corners of the engraved portion in Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, characteristic portions may be enlarged for convenience in order to make the features easier to understand, and the dimensional ratios of each component may not be the same as in reality. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not necessarily limited to them, and can be implemented with appropriate changes within the scope of the present invention.

[0016] (Forging mold) First, as one embodiment of the present invention, forging dies 1A and 1B shown in FIGS. 1 to 3 will be described.

[0017] Fig. 1 is a cross-sectional view showing the configuration of a forging die 1A used in the rough forming step, Fig. 2 is a cross-sectional view showing the configuration of a forging die 1B used in the finish forming step, and Fig. 3 is an enlarged cross-sectional view showing a main part of one die 6 constituting the forging die 1B.

[0018] In this embodiment, an example will be described in which an aluminum alloy material, which is a forming material M, is forged using a forging die 1A for rough forming shown in FIG. 1 and a forging die 1B for finish forming shown in FIGS. 2 and 3 to produce a suspension part, which is a forged product.

[0019] As shown in FIG. 1, the forging die 1A has a pair of dies 2 and 3 that are butted against each other, and is used when performing rough forming by flash removal forging while pressing a forming material M between the pair of dies 2 and 3.

[0020] In addition, the forging die 1A is configured so that one die (upper die in this embodiment) 2 of the pair of dies 2, 3 can be moved towards or away from the other die (lower die in this embodiment) 3 in a direction (up and down in this embodiment).

[0021] Between their opposing surfaces, the pair of dies 2, 3 have a die-engraved portion 4 that reflects the rough shape of the forged product, and a flash land 5 located outside the die-engraved portion 4, through which burrs B of the molding material M that protrude from the die-engraved portion 4 flow.

[0022] The die-sinking portion 4 has multiple (two in this embodiment) recesses 4a, 4b on the opposing surfaces of the pair of dies 2, 3, each of which reflects the shape of the forged product, in order to form a space that reflects the rough shape of the forged product between the opposing surfaces of the pair of dies 2, 3.

[0023] The flash land 5 has a first flat surface 5a on the side of one die 2 facing the other die 3, and a second flat surface 5b on the side of the other die 3 facing the one die 2, in order to form a space through which burrs B that protrude from the die-cutting portion 4 can flow.

[0024] Of these, the first flat surface 5a forms a horizontal surface from the boundary with the recessed portion 4a (embossed portion 4) in the direction in which burrs B flow, and is provided to extend to the end of one of the molds 2. On the other hand, the second flat surface 5b forms a horizontal surface from the boundary with the recessed portion 4b (embossed portion 4) in the direction in which burrs B flow, and is provided to extend to the end of the other mold 3. As a result, the first flat surface 5a and the second flat surface 5b are parallel to each other.

[0025] As shown in Figures 2 and 3, the forging die 1B has a pair of dies 6 and 7 that are butted against each other, and is used when performing finish forming by flash-removing forging while pressing the forming material M that has been roughly formed by the forging die 1A between the pair of dies 6 and 7.

[0026] In addition, the forging die 1B is configured so that one die (upper die in this embodiment) 6 of the pair of dies 6, 7 can be moved towards or away from the other die (lower die in this embodiment) 7 in a direction (up and down in this embodiment).

[0027] Between their opposing surfaces, the pair of dies 6, 7 have a die-engraved portion 8 that reflects the finished shape of the forged product, and a flash land 9 located outside the die-engraved portion 8, through which burrs B of the molding material M that protrude from the die-engraved portion 8 flow.

[0028] The die-sinking portion 8 has a plurality of recesses 8a, 8b (two in this embodiment) that reflect the shape of the forged product on the opposing surfaces of the pair of dies 6, 7, in order to form a space that reflects the finished shape of the forged product between the opposing surfaces of the pair of dies 6, 7. The recesses 8a, 8b have curved surface portions R at the corners on the flash land 9 side.

[0029] The flash land 9 has a first flat surface 9a, a first inclined surface 9b, a second flat surface 9c, a second inclined surface 9d and a fourth flat surface 9e on the side of the one die 6 facing the other die 7, and a third flat surface 9f on the side of the other die 7 facing the one die 6, in order to form a space through which burrs B that protrude from the die recess 8 can flow.

[0030] Of these, the first flat portion 9a forms a horizontal surface from the boundary with the recessed portion 8a (die-cutting portion 8) in the direction in which burrs B flow. On the other hand, the first inclined surface 9b forms a surface that is inclined from the boundary with the first flat portion 9a in a direction away from the surface facing the other mold 7. On the other hand, the second flat portion 9c forms a horizontal surface from the boundary with the first inclined surface 9b in the direction in which burrs B flow. On the other hand, the second inclined surface 9d forms a surface that is inclined from the boundary with the second flat portion 9c in a direction away from the surface facing the other mold 7. On the other hand, the fourth flat portion 9e forms a horizontal surface from the boundary with the second inclined surface 9d in the direction in which burrs B flow, and is provided to extend to the end of one of the molds 6. On the other hand, the third flat surface 9f forms a horizontal surface from the boundary with the recess 8b (die-sinking portion 8) in the direction in which the burr B flows, and is provided to extend to the end of the other mold 7. As a result, the first flat surface 9a, the second flat surface 9c, the fourth flat surface 9e and the third flat surface 9f are parallel to one another.

[0031] (Manufacturing method for aluminum alloy forgings) Next, a method for producing an aluminum alloy forged product using the forging dies 1A and 1B will be described with reference to FIGS.

[0032] 4 is a cross-sectional view showing the state during forging of the molding material M using the forging die 1A, and FIG. 5 is a cross-sectional view showing the state during forging of the molding material M using the forging die 1B.

[0033] When manufacturing an aluminum alloy forged product using the forging dies 1A and 1B, first, as shown in FIG. 4, the forging die 1A is used to perform rough forming by flash removal forging while pressing the forming material M between the pair of dies 2 and 3.

[0034] Specifically, molding material M is placed in the recess 4b (die-receiving portion 4) of the other die 3, and while one die 2 is lowered to a specified height, the molding material M is pressed between the one die 2 and the other die 3. At this time, the molding material M is deformed into a shape corresponding to the die-receiving portion 4, and burrs B of the molding material M that protrude from the die-receiving portion 4 flow out into the flash land 5. In this way, the molding material M is roughly formed by burr-removal forging using the forging die 1A.

[0035] Next, as shown in FIG. 5, the forging die 1B is used to perform finish forming by flash removal forging while pressing the forming material M roughly formed by the forging die 1A between the pair of dies 6 and 7.

[0036] Specifically, the molding material M after rough forming is placed in the recess 8b (die-receiving portion 8) of the other die 7, and while one die 6 is lowered to a specified height, the molding material M is pressed between the one die 6 and the other die 7. At this time, the molding material M is deformed into a shape corresponding to the die-receiving portion 8, and burrs B of the molding material M that protrude from the die-receiving portion 8 are discharged into the flash land 9. In this way, the molding material M is finish-formed by burr-removal forging using the forging die 1B.

[0037] In the method for manufacturing an aluminum alloy forged product of this embodiment, after the above-mentioned forging step, the following steps are performed: a solution treatment step in which the forged product obtained in the forging step is heated to solutionize the strain introduced into the cast product and solid-solve the solute elements; a quenching treatment step in which the solid-solution forged product obtained in the solution treatment step is rapidly cooled to form a supersaturated solid solution; and an aging treatment step in which the forged product obtained in the quenching treatment step is heated and held at a relatively low temperature to precipitate the supersaturated solid-solution elements and impart appropriate hardness. By undergoing these steps, it is possible to manufacture aluminum alloy forged products that will become the above-mentioned suspension parts.

[0038] For example, a cast or extruded aluminum alloy material can be used as the molding material M. The shape of the molding material M is not particularly limited, and can be selected appropriately from, for example, a cylindrical shape, a bent rod shape, a cubic shape, an irregular shape, and the like.

[0039] Although there are no particular limitations on the forging conditions for the molding material M, it is preferable to apply hot forging, which provides excellent formability. In this case, although there are no particular limitations on the heating method for the molding material M, for example, combustion heating or electric heating is preferably used.

[0040] In addition, in hot forging, it is preferable to preheat the forging dies 1A and 1B. The method for heating the forging dies 1A and 1B is not particularly limited, and well-known means such as a cartridge heater, an induction heating device, or a burner can be used.

[0041] Furthermore, a lubricant is applied to the forging dies 1A and 1B. The lubricant is not particularly limited, but examples thereof include graphite-based lubricants, non-graphite-based lubricants, water-soluble lubricants, and oil-based lubricants.

[0042] The pressurizing means using the forging dies 1A and 1B may be a mechanical press or a hydraulic press.

[0043] In the manufacturing method of the aluminum alloy forged product of this embodiment, in one of the dies 6 constituting the above-mentioned finish forming forging die 1B, a second flat surface portion 9c and a second inclined surface portion 9d that serve as a reinforcing structure are provided outside the first flat surface portion 9a and the first inclined surface portion 9b that form the flash land 9.

[0044] In this case, it is possible to prevent the flash land 9 from deforming toward the outside of the die recess 8 during forging. As a result, with the forging die 1B of this embodiment, it is possible to reduce stress generated in the corner (curved surface portion R) of the die recess 8 on the flash land 9 side.

[0045] Furthermore, as shown in FIG. 6 , in a cross section taken along the direction in which the pair of dies 6, 7 are butted together and along the direction in which the burr B of one of the dies 6 flows, the flash land 9 formed in one of the dies 6 preferably has a cross-sectional shape that does not come into contact with the curve L expressed by the following formula (1), where, in an XY coordinate system with the origin O being the boundary between the first flat surface portion 9a and the first inclined surface portion 9b, the direction in which the burr B flows being the X axis, and the direction toward the one of the dies 6 being the Y axis, the length between the first flat surfaces 9a on both sides of the die recessed portion 8 is defined as W, and the thickness of the burr B in the flash land 9 is defined as H.

number

[0046] In this case, the burr B flowing out to the flash land 9 does not come into contact with the second flat portion 9c and the second inclined portion 9d, so it is possible to prevent an increase in the forging load due to contact with the burr B.

[0047] Furthermore, when the length from the origin O to the boundary between the second flat surface portion 9c and the second inclined surface portion 9d is defined as d, the cross-sectional area of ​​the portion including the die-recessed portion 8 before molding the molding material M is defined as S1, and the cross-sectional area of ​​the portion including the die-recessed portion 8 and the first flat surface portion 9a during molding of the molding material M is defined as S2, it is preferable that the relationship of the following formula (2) be satisfied.

number

[0048] In this case, the burrs B formed in the molding material M after rough forming flow outward from the second flat surface portion 9c, thereby preventing contact with the second flat surface portion 9c and making it possible to prevent an increase in the forging load due to contact with the burrs B.

[0049] As described above, the forging die 1B of this embodiment can improve the life (durability) of one die 6. Therefore, the method for manufacturing an aluminum alloy forged product using this forging die 1B can manufacture the above-mentioned aluminum alloy forged product with high precision.

[0050] The present invention is not necessarily limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, forged products manufactured by applying the present invention are not limited to the suspension parts described above, but may be any product that can be forged using the forging die of the present invention.

[0051] Furthermore, although the forging die of the present invention is suitably used for the above-mentioned finish forming, the present invention can also be applied to forging dies other than those for finish forming. [Example]

[0052] The effects of the present invention will be made clearer by the following examples. Note that the present invention is not limited to the following examples and can be practiced with appropriate modifications within the scope of the present invention.

[0053] Example 1 In Example 1, in order to produce a damper fork for a four-wheeled vehicle as an aluminum alloy forged product, flash-removal forging was carried out using the forging dies 1A and 1B.

[0054] In this example, one mold 6 was used having the dimensions shown in Fig. 7. The molding material M was a 6000 series aluminum alloy material in the form of a cylindrical body having a diameter of 80 mm and a length of 274 mm.

[0055] First, using the forging die 1A, rough forming was performed by flash-removal forging while pressurizing the molding material M between the pair of dies 2 and 3. Specifically, the pair of dies 2 and 3 were heated to 150°C or higher, and molding material M heated to 500°C or higher was placed in the recess 4b (die-sinking portion 4) of the other die 3. One die 2 was lowered to a specified height, and the molding material M was pressed between the one die 2 and the other die 3, thereby performing rough forming of the molding material M.

[0056] Next, using the forging die 1B, finish forming was performed by flash-removal forging while pressurizing the molding material M that had been roughly formed by the forging die 1A between the pair of dies 6, 7. Specifically, the pair of dies 6, 7 were heated to 150°C or higher, and the molding material M that had been roughly formed and heated to 500°C or higher was placed in the recess 8b (die-cutting portion 8) of the other die 7. One die 6 was lowered to a specified height, and the molding material M was pressurized between the one die 6 and the other die 7, thereby finish forming the molding material M.

[0057] At this time, no trace of contact with the second flat portion 9c was found on the molding material M of the finish molding.

[0058] (Comparative Example 1) In Comparative Example 1, flash removal forging was performed under the same conditions as in Example 1, except that one of the dies 6 constituting the forging die 1B was replaced with one of the dies 6A shown in Figure 8, in which the second flat surface portion 9c and the second inclined surface portion 9d that form the reinforcing structure described above were omitted.

[0059] For Example 1 and Comparative Example 1, the stress generated at the corner (curved surface portion R) of the die-receiving portion 8 on the side of the flash land 9 was analyzed by computer simulation. The analysis results are shown in FIG.

[0060] As shown in Fig. 9, in Example 1, the stress generated in the corner (curved surface portion R) of the die-receiving portion 8 on the flash land 9 side was 83% of that in Comparative Example 1. When converted into die life, this represents a difference of more than 10 times.

[0061] From the above, by applying the above-mentioned reinforcing structure to one die 6 constituting the forging die 1B, it is possible to significantly improve the life (durability) of the die. [Explanation of symbols]

[0062] 1A...Forging die for rough forming 1B...Forging die for finish forming 2...One die 3...Other die 4...Die-recessed portion 4a, 4b...Recessed portion 5...Flash land 5a...First flat portion 5b...Second flat portion 6...One die 7...Other die 8...Die-recessed portion 8a, 8b...Recessed portion 9...Flash land 9a...First flat portion 9b...First inclined portion 9c...Second flat portion 9d...Second inclined portion 9e...Fourth flat portion 9f...Third flat portion M...Molding material B...Flash

Claims

1. A forging die having a pair of dies that are butted against each other and used when forging a forged product of a predetermined shape while pressurizing a molding material between the pair of dies, The pair of dies have, between their opposing surfaces, a die-engraved portion that reflects the shape of the forged product, and a flash land that is located outside the die-engraved portion and through which flash of molding material that has protruded from the die-engraved portion flows, the flash land is located on a surface of one of the pair of dies facing the other die, and includes, in order from the die-engraving portion side, a first flat surface portion parallel to the surface facing the other die, a first inclined surface portion inclined in a direction away from the surface facing the other die, a second flat surface portion parallel to the surface facing the other die, a second inclined surface portion inclined in a direction away from the surface facing the other die, and a third flat surface portion located on the surface of the other die facing the one die, and parallel to the first flat surface portion, And in a cross section along the direction in which the pair of dies are butted together and along the direction in which the burr of one of the dies flows, In an XY coordinate system in which the boundary between the first flat surface portion and the first inclined surface portion is the origin, the direction in which the burr flows is the X axis, and the direction toward one of the dies is the Y axis, when the length between the first flat surface portions on both sides of the die-sinking portion is defined as W and the thickness of the burr at the flash land is defined as H, A forging die having a cross-sectional shape that does not contact the curve expressed by the following formula (1): [Equation 1]

2. 2. The forging die according to claim 1, wherein the die recess is located on a surface of the one die facing the other die and includes a curved surface portion that is curved at a corner on the flash land side.

3. When the length from the origin to the boundary between the second flat surface portion and the second inclined surface portion is defined as d, the cross-sectional area of ​​the portion including the die-recessed portion before molding of the molding material is defined as S1, and the cross-sectional area of ​​the portion including the die-recessed portion and the first flat surface portion during molding of the molding material is defined as S2, 3. The forging die according to claim 1, wherein the following formula (2) is satisfied: [Equation 2]

4. Using the forging die according to any one of claims 1 to 3, A method for manufacturing an aluminum alloy forging, comprising forging the aluminum alloy material, which is the molding material, between the pair of dies while applying pressure to form an aluminum alloy forging of a predetermined shape.

5. 5. The method for manufacturing an aluminum alloy forged product according to claim 4, wherein the forging die is used for finish forming after rough forming.

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