Forging mold

Abstract

To provide a forging mold which can enhance rigidity and therefore, can make a recessed molding part on a molding surface wide.SOLUTION: A forging mold 10 is configured so that a lower die 18 is fixed to a lower holder 141 by a fixing member 161. The lower die 18 comprises: a first molding surface 221; a first recessed molding part 281 which is hollow to the first molding surface 221; a first holding surface 241 contacting the lower holder 141; and a side surface 321 connecting an outer edge of the first molding surface 221 and an outer edge of the first holding surface 241. A side surface 321 of the lower die 18 has: a first side surface part 341 continuous to the outer edge of the first molding surface 221; and a second side surface part 342 continuous to the outer edge of the first holding surface 241. The side surface 321 of the lower die 18 has a first groove part 301 for fixing which is hollow in a horizontal direction to the first side surface part 341 and second sided surface part 342. To the first groove part 301 for fixing, a fixing member 161 fixed to the lower holder 141 is engaged.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a forging die. [Background technology]

[0002] The forging die of Patent Document 1 includes a lower die having a lower molding surface, an upper die having an upper molding surface facing the lower die, a bolster that abuts against the lower surface of the lower die, and a lower holder fixed to the bolster. The side surface of the lower die has a recess that is recessed inward from the side surface, and the recess extends from the center of the lower die in the height direction to the lower molding surface. A fixing member provided on the upper part of the lower holder is engaged with the upper part of the recess, thereby fixing the lower die to the lower bolster. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 60-28938 Summary of the Invention [Problem to be solved by the invention]

[0004] In the forging die of Patent Document 1, a fixing member is engaged with a recess extending to the lower molding surface, and the lower die is biased downward to be fixed to the lower bolster. Therefore, the area of ​​the lower molding surface is reduced by the amount of the recess, and the size of the molded product that can be molded on the lower molding surface is reduced accordingly. The upper die is biased upward to be fixed to the upper bolster by engaging a fixing member with a recess extending to the upper molding surface. Therefore, the area of ​​the upper molding surface is reduced by the amount of the recess. In addition, even if the side surface of the lower die is a trapezoidal shape tapered toward the upper side (lower molding surface) and the side surface of the upper die is a trapezoidal shape tapered toward the lower side (upper molding surface), there is a problem that the areas of the upper molding surface and the lower molding surface are each reduced.

[0005] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0006] An aspect of the present invention is a forging die comprising a lower die and an upper die movable in a vertical direction relative to the lower die, wherein a first die, which is one of the lower die and the upper die, and a second die, which is the other of the lower die and the upper die, each have a molding surface, the molding surface of the first die and the molding surface of the second die face each other, and each of the first die and the second die are fixed to a holder by a fixing member, wherein at least the first die has a concave molding portion that is recessed into the molding surface corresponding to the shape of the molded product, a holding surface that abuts against a support surface of the holder that intersects with the movement direction of the upper die, and a side that connects an outer edge of the molding surface and an outer edge of the holding surface, and the side has a first side portion that is continuous with the outer edge of the molding surface, a second side portion that is continuous with the outer edge of the holding surface, and a fixing groove portion that is provided between the first side portion and the second side portion, is recessed horizontally relative to the first side portion and the second side portion, and engages with the fixing member. Effect of the Invention

[0007] According to the present invention, in the forging die, the first side portion connected to the outer edge of the molding surface protrudes horizontally beyond the fixing groove. Therefore, compared to a configuration in which the fixing groove for engaging the fixing member extends to the molding surface and a configuration in which the lower die and the upper die are formed in a trapezoidal shape tapered toward the molding surface, a larger area of ​​the molding surface of the first die can be secured. This makes it possible to increase the rigidity of at least the first die, and accordingly to form a wider concave molding portion on the molding surface. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an overall cross-sectional view showing a forging die according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing the overall configuration of the forging die shown in FIG. 1 with the upper die open. [Diagram 3]FIG. 3 is a plan view of the lower mold as viewed from the first molding surface. [Figure 4] 4 is an enlarged cross-sectional view showing the vicinity of a first end side surface of the lower mold shown in FIG. [Diagram 5] FIG. 5 is a characteristic diagram showing the relationship between the stress generated on the side surface during molding of a molded product and the ratio of the groove depth of the fixing groove to the molding surface length. [Figure 6] FIG. 6 is a plan view of the upper mold as viewed from the second molding surface. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing the vicinity of the second end side surface of the upper die shown in FIG. [Figure 8] Fig. 8A is an enlarged cross-sectional view showing a case where a first molding surface of a lower mold is subjected to resinking, and Fig. 8B is an enlarged cross-sectional view showing a case where a second molding surface of an upper mold is subjected to resinking. [Figure 9] FIG. 9 is a characteristic diagram showing the relationship between the stress generated on the side surface during molding of a molded product and the ratio of the first distance to the second distance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] As shown in Fig. 1, the forging die 10 according to this embodiment includes a first die 121, a second die 122 facing the first die 121, a holder 14, and fixing members 161 and 162. The forging die 10 obtains a molded product C (see Fig. 2) by closing the first die 121 and the second die 122 close to each other. As shown in Fig. 2, the molded product C is, for example, a crankshaft used in an internal combustion engine. Note that the molded product C is not limited to being a crankshaft.

[0010] As shown in FIG. 1, the first die 121 is either the lower die 18 or the upper die 20 arranged above the lower die 18. The second die 122 is the other of the lower die 18 or the upper die 20. Below, a case will be described in which the first die 121 is the lower die 18 arranged at the bottom of the forging die 10, and the second die 122 is the upper die 20 arranged above the lower die 18. The first die 121 is referred to as the lower die 18, and the second die 122 is referred to as the upper die 20. The lower die 18 and the upper die 20 are formed from a metal material (for example, an alloy tool steel).

[0011] As shown in Fig. 3, the lower mold 18 is formed in a rectangular shape that is long in one direction and short in a direction perpendicular to the one direction. Hereinafter, the short direction of the lower mold 18 is referred to as the width direction. As shown in Fig. 2, the lower mold 18 includes a first molding surface 221 (also referred to as "molding surface 22"), a first holding surface 241 (also referred to as "holding surface 24"), a first outer peripheral surface 261, a first concave molding portion 281 (also referred to as "concave molding portion 28"), and a first fixing groove 301 (also referred to as "fixing groove 30").

[0012] The first molding surface 221 is formed on the upper part of the lower mold 18. The first molding surface 221 is a surface that faces the upper mold 20. The first molding surface 221 extends in a direction perpendicular to the moving direction of the upper mold 20. The first holding surface 241 is provided on the lower part of the lower mold 18. The first holding surface 241 extends in the horizontal direction. The first holding surface 241 abuts against the holder 14.

[0013] As shown in Fig. 3, the first outer peripheral surface 261 is annular and surrounds the side of the lower mold 18. The first outer peripheral surface 261 has a plurality of side surfaces 321. The plurality of side surfaces 321 connect the outer edge of the first molding surface 221 and the outer edge of the first holding surface 241. The plurality of side surfaces 321 extend in the up-down direction at the outer edge of the lower mold 18 (see Fig. 2). Of the plurality of side surfaces 321, two first end side surfaces 34 each having a first fixing groove 301 are provided at one end and the other end in the longitudinal direction of the lower mold 18.

[0014] As shown in FIG. 2, the first end side surface 34 has a first side surface portion 341 and a second side surface portion 342. The first side surface portion 341 is provided on an upper portion of the side surface 321. The first side surface portion 341 is continuous with the outer edge portion of the first molding surface 221. The first side surface portion 341 extends in the width direction which is a horizontal direction perpendicular to the moving direction of the upper mold 20 (see FIG. 3). The second side surface portion 342 is provided on a lower portion of the side surface 321. The second side surface portion 342 is continuous with the outer edge portion of the first holding surface 241.

[0015] The first concave molding portion 281 is formed so as to be recessed downward relative to the first molding surface 221. The first concave molding portion 281 is formed corresponding to the shape of the molded product C. The first concave molding portion 281 has a plurality of first concave molding grooves 36. The plurality of first concave molding grooves 36 are arranged along the longitudinal direction of the lower mold 18.

[0016] The first concave molding groove 36 includes a set of first end molding grooves 38. In the plurality of first concave molding grooves 36, the first end molding grooves 38 are disposed at one end and the other end of the lower mold 18. In the plurality of first concave molding grooves 36, the set of first end molding grooves 38 is disposed closest to the first end side surface 34.

[0017] As shown in FIG. 3, in the width direction of the lower mold 18, the width W1 of the first side surface portion 341 is equal to or larger than the maximum width W2 of the first concave molding portion 281 (W1>W2).

[0018] As shown in FIG. 2, the first fixing groove 301 is provided in the first end side surface 34 of the lower mold 18. The fixing member 161 can be engaged with the first fixing groove 301. The first fixing groove 301 is provided between the first side surface portion 341 and the second side surface portion 342. The first fixing groove 301 is recessed in the horizontal direction relative to the first side surface portion 341 and the second side surface portion 342. As shown in FIG. 4, the first fixing groove 301 has a dimension in the vertical direction larger than a horizontal groove depth D1 which is the longitudinal direction of the lower mold 18. The first fixing groove 301 has a bottom portion 40. In the groove depth direction of the first fixing groove 301, the bottom portion 40 is disposed furthest from the first end side surface 34. The bottom portion 40 and the side surface 321 are approximately parallel. That is, the bottom portion 40 extends along the vertical direction. The groove depth direction of the first fixing groove portion 301 and the first side surface portion 341 are perpendicular to each other.

[0019] The first fixing groove 301 has a groove depth D1 in the horizontal direction. In the longitudinal direction of the lower die 18, the groove depth D1 is the distance between the side surface 321 (first side surface portion 341) and the bottom portion 40. The shortest distance from the first end forming groove 38 to the side surface 321 (first side surface portion 341) is the forming surface length L1. The relationship between the groove depth D1 and the forming surface length L1 of the first fixing groove 301 will be described with reference to FIG. 5. FIG. 5 shows the relationship between the stress P generated in the side surface 321 (first side surface portion 341) when the molded product C is molded in the forging die 10 and the ratio of the groove depth D1 to the forming surface length L1. The larger the ratio (D1 / L1) of the groove depth D1 to the forming surface length L1, the larger the stress P generated in the side surface 321. If the threshold value of the stress P generated during molding is 1350 MPa, it is possible to maintain the stress P at or below the threshold value (1350 MPa) by satisfying the relationship D1 / L1≦0.229. In other words, it is preferable to satisfy the relationship D1 / L1≦0.229.

[0020] In the groove depth direction of the first fixing groove 301, the height E1 of the first side surface portion 341 relative to the bottom portion 40 is the same as the height E2 of the second side surface portion 342 relative to the bottom portion 40. The height E1 of the first side surface portion 341 and the height E2 of the second side surface portion 342 may be different. When the heights E1 and E2 are different, it is preferable that the height E1 of the first side surface portion 341 relative to the bottom portion 40 be equal to or greater than ½ of the height E2 of the second side surface portion 342 relative to the bottom portion 40.

[0021] In the direction of movement of the upper mold 20, it is preferable that a first distance H1, which is the distance between the end 341a of the first side portion 341 that is farthest from the first molding surface 221 and the first molding surface 221, and a second distance H2, which is the distance from the first molding surface 221 to the deepest portion 381 of the first end molding groove 38, satisfy the relationship H1 ≧ H2.

[0022] The first fixing groove 301 further includes a first engagement end 421. The first engagement end 421 is provided at a lower part of the first fixing groove 301. The first engagement end 421 is an end with which the fixing member 161 is engaged. The first engagement end 421 and the bottom portion 40 are substantially perpendicular to each other.

[0023] 2, the upper mold 20 is disposed above the lower mold 18. The upper mold 20 includes a second molding surface 222, a second holding surface 242, a second outer circumferential surface 262, a second concave molding portion 282, and a second fixing groove portion 302.

[0024] The second molding surface 222 is formed on the lower part of the upper mold 20 and faces the first molding surface 221 of the lower mold 18. The second molding surface 222 extends in a direction perpendicular to the direction in which the upper mold 20 moves.

[0025] The second holding surface 242 is provided on an upper portion of the upper mold 20. The second holding surface 242 extends in the horizontal direction. The second holding surface 242 abuts against the holder 14.

[0026] As shown in Fig. 6, the second outer peripheral surface 262 is annular and surrounds the side of the upper mold 20. The second outer peripheral surface 262 has a plurality of side surfaces 322. As shown in Fig. 2, the plurality of side surfaces 322 connect the outer edge of the second molding surface 222 and the outer edge of the second holding surface 242. The plurality of side surfaces 322 extend in the up-down direction at the outer edge of the upper mold 20. Of the plurality of side surfaces 322, two second end side surfaces 44 having second fixing groove portions 302 are provided at one end and the other end of the upper mold 20 in the longitudinal direction.

[0027] As shown in FIG. 7, the second end side surface 44 has a first side surface portion 441 and a second side surface portion 442. The first side surface portion 441 is provided at the lower part of the side surface 322. The first side surface portion 441 is continuous with the outer edge part of the second molding surface 222. The first side surface portion 441 extends in the width direction which is a horizontal direction perpendicular to the moving direction of the upper mold 20. The second side surface portion 442 is provided at the upper part of the side surface 322. The second side surface portion 442 is continuous with the outer edge part of the second holding surface 242.

[0028] As shown in FIG. 2, the second concave molding portion 282 is formed to be recessed upward with respect to the second molding surface 222. The second concave molding portion 282 is formed to correspond to the shape of the molded product C. The second concave molding portion 282 faces the first concave molding portion 281 of the lower mold 18. The second concave molding portion 282 has a plurality of second concave molding grooves 46. The plurality of second concave molding grooves 46 are arranged along the longitudinal direction of the upper mold 20. When the lower mold 18 and the upper mold 20 are closed, a cavity is formed by the first concave molding portion 281 and the second concave molding portion 282. The molded product C is molded by the first concave molding portion 281 of the lower mold 18 and the second concave molding portion 282 of the upper mold 20.

[0029] 6, the second concave molding groove 46 includes a set of second end portion molding grooves 48. Of the multiple second concave molding grooves 46, the second end portion molding grooves 48 are disposed at one end and the other end of the upper mold 20. Of the multiple second concave molding grooves 46, the set of second end portion molding grooves 48 is disposed closest to the second end portion side surface 44. In the width direction of the upper mold 20, the width W1 of the first side surface portion 441 is equal to or greater than the maximum width W2 of the second concave molding portion 282 (W1>W2).

[0030] As shown in FIG. 2, the second fixing groove 302 is provided on the second end side surface 44 of the upper mold 20. The fixing member 162 can be engaged with the second fixing groove 302. The second fixing groove 302 is provided between the first side surface portion 441 and the second side surface portion 442. The second fixing groove 302 is recessed in the horizontal direction with respect to the first side surface portion 441 and the second side surface portion 442. As shown in FIG. 7, the second fixing groove 302 has a dimension in the vertical direction larger than a horizontal groove depth D2 which is the longitudinal direction of the upper mold 20. The second fixing groove 302 has a bottom portion 40. In the groove depth direction of the second fixing groove 302, the bottom portion 40 is disposed furthest from the second end side surface 44. The bottom portion 40 and the side surface 322 are approximately parallel. That is, the bottom portion 40 extends along the vertical direction. The groove depth direction of the second fixing groove portion 302 and the first side surface portion 441 are perpendicular to each other.

[0031] The second fixing groove 302 has a groove depth D2 in the horizontal direction. In the longitudinal direction of the upper mold 20, the groove depth D2 is the distance between the side surface 322 and the bottom portion 40. The distance from the second end molding groove 48 to the second end side surface 44 is the molding surface length L2. At this time, it is preferable that the groove depth D2 and the molding surface length L2 of the second fixing groove 302 satisfy the relationship of D2 / L2≦0.229. If the threshold value of the stress P generated at the side surface 322 during molding is 1350 MPa, it is possible to maintain the stress P below the threshold value (1350 MPa) by satisfying the relationship of D2 / L2≦0.229. Note that the relationship between the groove depth D2 and the molding surface length L2 of the second fixing groove 302 is the same as the relationship between the groove depth D1 and the molding surface length L1 of the first fixing groove 301 shown in FIG. 5, so a detailed description will be omitted.

[0032] In the groove depth direction of the second fixing groove 302, the height E1 of the first side surface portion 441 relative to the bottom portion 40 is the same as the height E2 of the second side surface portion 442 relative to the bottom portion 40. Note that the height E1 of the first side surface portion 441 relative to the bottom portion 40 may be equal to or greater than ½ of the height E2 of the second side surface portion 442 relative to the bottom portion 40.

[0033] In the direction of movement of the upper mold 20, it is preferable that a first distance H1, which is the distance between the end 441a of the first side portion 441 that is farthest from the second molding surface 222 and the second molding surface 222, and a second distance H2, which is the distance from the second molding surface 222 to the deepest portion 481 of the second end molding groove 48, satisfy the relationship H1 ≧ H2.

[0034] The second fixing groove 302 further includes a second engagement end 422. The second engagement end 422 is provided at an upper portion of the second fixing groove 302. The second engagement end 422 is an end with which the fixing member 162 is engaged. The second engagement end 422 and the bottom portion 40 are substantially perpendicular to each other.

[0035] As shown in FIG. 1, the holder 14 includes a lower holder 141 that holds the lower die 18, and an upper holder 142 that holds the upper die 20. The lower holder 141 is provided below the lower die 18. The lower holder 141 includes a first support surface 501 and a first extension portion 521. The first support surface 501 is an upper surface of the lower holder 141. The first support surface 501 extends in the horizontal direction and abuts against a first holding surface 241 of the lower die 18. The first extension portion 521 extends in the longitudinal direction beyond one end and the other end of the lower die 18 in the longitudinal direction.

[0036] The upper holder 142 is provided above the upper mold 20. The upper holder 142 includes a second support surface 502 and a second extension portion 522. The second support surface 502 is the lower surface of the upper holder 142. The second support surface 502 extends in the horizontal direction and is in contact with the second holding surface 242 of the upper mold 20. The second extension portion 522 extends in the longitudinal direction beyond one end and the other end of the upper mold 20 in the longitudinal direction. The upper holder 142 is connected to a pressing mechanism (not shown) and is provided so as to be displaceable in the up-down direction together with the upper mold 20.

[0037] A pair of fixing members 161 are provided facing one end and the other end of the lower mold 18. The fixing members 161 face the first fixing groove portion 301 and extend in the horizontal direction. A pair of fixing members 162 are provided facing one end and the other end of the upper mold 20. The fixing members 162 face the second fixing groove portion 302 and extend in the horizontal direction.

[0038] As shown in FIG. 1, each of the fixing members 161, 162 includes a fixing portion 54 and an engaging portion 56. The fixing portion 54 is provided at one end of the fixing members 161, 162. As shown in FIG. 4, the fixing portion 54 of the fixing member 161 faces the first extending portion 521 of the lower mold 18 and is fixed to the first extending portion 521. The fixing portion 54 is a fixed end that is fixed to the first extending portion 521 by a fastening member 58. The first extending portion 521 and the fixing portion 54 are approximately parallel. The fastening direction of the fixing portion 54 is a direction perpendicular to the extending direction of the first extending portion 521 and the fixing portion 54.

[0039] 7, the fixing portion 54 of the fixing member 162 faces the second extending portion 522 of the upper mold 20 and is fixed to the second extending portion 522. The fixing portion 54 is a fixed end that is fixed to the second extending portion 522 by a fastening member 58. The second extending portion 522 and the fixing portion 54 are approximately parallel. The fastening direction of the fixing portion 54 is a direction perpendicular to the extending direction of the second extending portion 522 and the fixing portion 54.

[0040] As shown in Fig. 1, the engagement portion 56 is provided on the other end of the fixing members 161, 162. As shown in Fig. 4, the engagement portion 56 of the fixing member 161 is inserted into the first fixing groove portion 301 and abuts against the first engagement end portion 421, thereby engaging with the first engagement end portion 421. The engagement portion 56 is a free end. As the engagement portion 56 of the fixing member 161 engages with the first engagement end portion 421, the lower die 18 is clamped between the fixing member 161 and the lower holder 141.

[0041] 7, the engaging portion 56 of the fixing member 162 is inserted into the second fixing groove portion 302 and abuts against the second engaging end portion 422, thereby engaging the second engaging end portion 422. As a result of the engaging portion 56 of the fixing member 162 engaging with the second engaging end portion 422, the upper die 20 is clamped between the fixing member 162 and the upper holder 142.

[0042] The fixing groove 30 may be provided in only one of the lower mold 18 and the upper mold 20.

[0043] Next, a case where the forging die 10 is used to form the formed product C will be described.

[0044] First, as shown in FIG. 2, the upper die 20 is placed above the lower die 18 in an open state, and a material (not shown) is placed in the first concave molding portion 281. The upper die 20 is lowered by a pressing mechanism (not shown), and the second molding surface 222 of the upper die 20 and the first molding surface 221 of the lower die 18 come into contact with each other, as shown in FIG. 1. A cavity is formed by the second concave molding portion 282 of the upper die 20 and the first concave molding portion 281 of the lower die 18, and the material is forged in the cavity. The material is processed into a shape corresponding to the multiple first concave molding grooves 36 and the multiple second concave molding grooves 46, and a molded product C based on the shapes of the first and second concave molding portions 281, 282 is molded.

[0045] The upper die 20 is raised and separated from the lower die 18 to create an open die state, and the formed product C is removed, completing the forging of the product C.

[0046] As described above, repeated use of the forging die 10 may cause wear on the first molding surface 221 of the lower die 18 and the second molding surface 222 of the upper die 20. In this case, resinking is performed to correct the die shape (first and second concave molding portions 281, 282) by cutting the first molding surface 221 and the second molding surface 222.

[0047] As shown in FIG. 8A, in the resinking process for the lower mold 18, the first molding surface 221 is cut by a predetermined height toward the first holding surface 241 along the moving direction of the upper mold 20. The amount of cutting of the first molding surface 221 is constant along the first molding surface 221. The cut new first molding surface 221a becomes approximately horizontal. The first molding surface 221 is formed with a first concave molding portion 281 having the same shape as before the resinking process. By cutting the first molding surface 221, the new first molding surface 221a approaches the first holding surface 241 and the first fixing groove portion 301. Therefore, as shown in FIG. 4, the first distance H1a from the first molding surface 221a to the end 341a of the first side surface portion 341 after the resinking process is performed as shown in FIG. 8A becomes smaller (H1a

[0048] In the moving direction of the upper die 20, the distance between the first molding surface 221a and the end 341a of the first side portion 341 is defined as the first distance H1a, and the distance from the first molding surface 221a to the deepest part 381 of the first end molding groove 38 is defined as the second distance H2a. The relationship between the stress P generated in the side 321 (first side portion 341) when molding the molded product C with the forging die 10 and the ratio of the first distance H1a to the second distance H2a will be described with reference to FIG. 9. As shown in FIG. 9, the larger the ratio (H1a / H2a) of the first distance H1a to the second distance H2a, the smaller the stress P generated in the side 321 becomes. When the threshold value of the stress P generated during molding is 1350 MPa, it is possible to maintain the stress P at or below the threshold value (1350 MPa) by satisfying the relationship H1a / H2a≧0.53. That is, it is preferable to satisfy the relationship H1a / H2a≧0.53.

[0049] ​As shown in FIG. 8B, in the resinking process for the upper mold 20, the second molding surface 222 is cut by a predetermined height toward the second holding surface 242 along the moving direction of the upper mold 20. The amount of cutting of the second molding surface 222 is constant along the second molding surface 222. The cut new second molding surface 222a becomes approximately horizontal. The second molding surface 222 is formed with a second concave molding portion 282 having the same shape as before the resinking process. By cutting the second molding surface 222, the new second molding surface 222a approaches the second holding surface 242 and the second fixing groove portion 302. Therefore, as shown in FIG. 8B, the first distance H1b from the second molding surface 222a to the end 441a of the first side surface portion 441 after the resinking process is smaller (H1b

[0050] In the moving direction of the upper mold 20, the distance from the second molding surface 222a to the end 441a of the first side portion 441 is defined as the first distance H1b, and the distance from the second molding surface 222a to the deepest part 481 of the second end molding groove 48 is defined as the second distance H2b. As shown in FIG. 9, the larger the ratio (H1b / H2b) of the first distance H1b to the second distance H2b, the smaller the stress P generated in the side 322 (first side portion 441). If the threshold value of the stress P generated during molding is 1350 MPa, it is possible to maintain the stress P at or below the threshold value (1350 MPa) by satisfying the relationship H1b / H2b ≧ 0.53. In other words, it is preferable to satisfy the relationship H1b / H2b ≧ 0.53.

[0051] This embodiment provides the following advantages.

[0052] ​As shown in Fig. 2, the forging die 10 includes a first die 121, which is one of the lower die 18 and the upper die 20, and a second die 122, which is the other of the lower die 18 and the upper die 20, each having a first molding surface 221 and a second molding surface 222, and the first molding surface 221 of the first die 121 and the second molding surface 222 of the second die 122 face each other, and each of the first die 121 and the second die 122 is fixed to the holder 14 by fixing members 161 and 162. At least the first die 121 includes a side surface 321 connecting the outer edge of the first molding surface 221 and the outer edge of the first holding surface 241, and includes a first fixing groove portion 301 between a first side surface portion 341 continuing to the outer edge of the first molding surface 221 and a second side surface portion 342 continuing to the outer edge of the first holding surface 241. The first fixing groove 301 is recessed in the horizontal direction relative to the first side surface portion 341 and the second side surface portion 342, and the fixing member 161 is engaged therewith.

[0053] According to this configuration, the first side surface portion 341 continuing to the outer edge portion of the molding surface 22 protrudes horizontally beyond the fixing groove portion 30. Therefore, compared to a configuration in which the fixing groove portion 30 for engaging the fixing members 161, 162 is extended to the molding surface 22, and a configuration in which the lower mold 18 and the upper mold 20 are formed in a trapezoidal shape tapered toward the molding surface 22, a larger area of ​​the molding surface 22 of the first mold 121 can be secured. This makes it possible to increase the rigidity of at least the first mold 121, and accordingly to form a wider concave molded portion 28 (first concave molded portion 281) on the molding surface 22.

[0054] 4, the fixing groove 30 (first fixing groove 301) of the first die 121 has a groove depth D1 in the horizontal direction, and the first concave molding portion 281 has a first end portion molding groove 38 closest to the side surface 321 having the fixing groove 30. The groove depth D1 of the fixing groove 30 and the molding surface length L1, which is the distance from the first end portion molding groove 38 to the side surface 321, satisfy the relationship D1 / L1≦0.229 (see FIG. 5).

[0055] By ensuring the molding surface length L1 of the first die 121 such that the ratio of the groove depth D1 of the fixing groove 30 to the molding surface length L1 is 0.229 or less, it is possible to effectively suppress the stress P generated on the side surface 321 having the fixing groove 30 when molding the molded product C. This makes it possible to suppress cracks in the first die 121 caused by stress concentration, and improve the durability of the first die 121.

[0056] The concave molding portion 28 (first concave molding portion 281) has a first end molding groove 38 closest to the side surface 321 having the fixing groove portion 30, and in the movement direction of the upper mold 20, a first distance H1 which is the distance between the end portion 341a of the first side surface portion 341 which is farthest from the molding surface 22 (first molding surface 221) and the molding surface 22, and a second distance H2 which is the distance from the molding surface 22 to the deepest portion 381 of the first end molding groove 38 satisfy the relationship H1 / H2 ≧ 0.53 (see Figure 9).

[0057] 8A, even when the molding surface 22 is scraped toward the fixing groove 30 by resinking, the vertical thickness of the first side surface 341 is ensured so that the ratio of the vertical thickness of the first side surface 341 to the height of the deepest part 381 of the concave molding portion 28 is 0.53 or more, thereby effectively suppressing the stress P generated in the side surface 321 having the fixing groove 30 when molding the molded product C. Therefore, cracks in the first mold 121 caused by stress concentration are suppressed, and the durability of the first mold 121 can be improved.

[0058] 4, the first fixing groove 301 has a bottom 40 that is furthest from the side surface 321 in the groove depth direction, and in the groove depth direction, the height E1 of the first side surface 341 relative to the bottom surface 40 is equal to or more than ½ of the height E2 of the second side surface 342 relative to the bottom surface 40. As a result, in the side surface 321 of the first mold 121, the first side surface 341 protrudes from the bottom surface 40 of the fixing groove 30 at a height equal to or more than ½ of the second side surface 342, so that the area of ​​the molding surface 22 continuous with the first side surface 341 can be ensured.

[0059] The first fixing groove 301 has a bottom 40 that is furthest from the side surface 321 in the groove depth direction, and in the groove depth direction, a height E1 of the first side surface portion 341 relative to the bottom surface 40 is the same as a height E2 of the second side surface portion 342 relative to the bottom surface 40. This makes it easy to manufacture the first mold 121 by making the first side surface portion 341 and the second side surface portion 342 into the same plane.

[0060] In the movement direction of the upper die 20, the first distance H1 and the second distance H2 satisfy the relationship H1 ≧ H2. As a result, by ensuring that the first distance H1 from the molding surface 22 to the end 341a of the first side surface portion 341 is greater than the second distance H2 from the molding surface 22 to the deepest part 381 of the first end molding groove 38, it is possible to ensure a large area of ​​the molding surface 22 in the first die 121 even when the molding surface 22 is resinked, as shown in Fig. 8A.

[0061] 3, the first side surface portion 341 extends in a width direction, which is a horizontal direction perpendicular to the groove depth direction of the fixing groove portion 30 and perpendicular to the moving direction of the upper mold 20. Since the first side surface portion 341 extends in the width direction, the rigidity of the first mold 121 can be effectively increased.

[0062] In the width direction of the first die 121, the width W1 of the first side surface portion 341 is equal to or larger than the width W2 of the concave molded portion 28. By making the width W1 of the first side surface portion 341 equal to or larger than the width W2 of the concave molded portion 28 in the first die 121, a wide region for increasing rigidity can be secured in the width direction, and the generation of stress P during molding can be effectively suppressed.

[0063] In addition to the above disclosure, the following notes are also disclosed.

[0064] (Appendix 1) The forging die (10) comprises a lower die (18) and an upper die (20) that is movable in the vertical direction relative to the lower die, and a first die (121) which is one of the lower die and the upper die, and a second die (122) which is the other of the lower die and the upper die each have a molding surface (22), the molding surface of the first die faces the molding surface of the second die, and each of the first die and the second die is fixed to a holder (14) by a fixing member (161, 162). At least the first mold comprises a concave molding portion (28) recessed into the molding surface corresponding to the shape of the molded product (C), a holding surface (24) abutting against a support surface (501, 502) of the holder that intersects with the movement direction of the upper mold, and a side surface (321, 322) connecting the outer edge portion of the molding surface and the outer edge portion of the holding surface, the side surface comprising a first side portion (341, 441) connected to the outer edge portion of the molding surface, a second side portion (342, 442) connected to the outer edge portion of the holding surface, and a fixing groove portion (30) provided between the first side portion and the second side portion, recessed horizontally into the first side portion and the second side portion, and into which the fixing member engages.

[0065] According to this configuration, in the forging die, the first side portion connected to the outer edge of the molding surface protrudes horizontally beyond the fixing groove. Therefore, compared to a configuration in which the fixing groove for engaging the fixing member extends to the molding surface and a configuration in which the lower die and the upper die are formed in a trapezoidal shape tapered toward the molding surface, a larger area of ​​the molding surface of the first die can be secured. This makes it possible to increase the rigidity of at least the first die, and accordingly to form a wider concave molding portion on the molding surface.

[0066] (Appendix 2) In the forging die described in Appendix 1, the fixing groove portion has a groove depth (D1, D2) in the horizontal direction, the concave forming portion has an end forming groove (38, 48) closest to the side surface having the fixing groove portion, and the groove depth and the forming surface lengths L1, L2, which are the distances from the end forming groove to the side surface, may satisfy the relationship D1, D2 / L1, L2≦0.229.

[0067] According to this configuration, by ensuring the molding surface length of the first mold so that the ratio of the groove depth of the fixing groove to the molding surface length is 0.229 or less, it is possible to effectively suppress the stress generated on the side surface having the fixing groove when molding a molded product, thereby suppressing cracks in the first mold caused by stress concentration and improving the durability of the first mold.

[0068] (Appendix 3) In the forging die described in Appendix 1 or 2, the concave forming portion has an end forming groove closest to the side surface having the fixing groove portion, and in the movement direction of the upper die, a first distance (H1) that is the distance between the end (341a, 441a) of the first side surface portion that is farthest from the forming surface and the forming surface, and a second distance (H2) that is the distance from the forming surface to the deepest part (381, 481) of the end forming groove may satisfy the relationship H1 / H2 ≧ 0.53.

[0069] With this configuration, even if the molding surface is cut toward the fixing groove by resinking, the vertical thickness of the first side surface is ensured so that the ratio of the vertical thickness of the first side surface to the height of the deepest part of the concave molding portion is 0.53 or more, thereby effectively suppressing the stress generated on the side surface having the fixing groove when molding the molded product. This suppresses cracks in the first mold due to stress concentration, and improves the durability of the first mold.

[0070] (Appendix 4) In the forging die described in Appendix 1, the fixing groove portion has a bottom (40) that is furthest from the side surface in the groove depth direction, and in the groove depth direction, a height (E1) of the first side surface portion relative to the bottom may be equal to or greater than 1 / 2 of a height (E2) of the second side surface portion relative to the bottom.

[0071] With this configuration, the first side portion protrudes from the bottom of the fixing groove at a height that is half or more of the second side portion, thereby ensuring the area of ​​the molding surface that continues to the first side portion.

[0072] (Appendix 5) In the forging die described in Appendix 1, the fixing groove portion has a bottom portion that is furthest from the side surface in the groove depth direction, and in the groove depth direction, a height of the first side surface portion relative to the bottom portion and a height of the second side surface portion relative to the bottom portion may be the same.

[0073] According to this configuration, the first side surface portion and the second side surface portion are flush with each other, which facilitates the manufacture of the first mold.

[0074] (Appendix 6) In the forging die described in Supplementary Note 3, the first distance and the second distance may satisfy a relationship of H1≧H2 in the moving direction of the upper die.

[0075] With this configuration, by ensuring that the first distance from the molding surface to the end of the first side portion is greater than the second distance from the molding surface to the deepest part of the end molding groove, a large area of ​​the molding surface can be ensured even when the molding surface is resink processed.

[0076] (Appendix 7) In the forging die described in Appendix 1, the first side portion may extend in a width direction that is a horizontal direction perpendicular to a groove depth direction of the fixing groove portion and perpendicular to a movement direction of the upper die.

[0077] According to this configuration, since the first side surface portion extends in the width direction, the rigidity of the first mold can be effectively increased.

[0078] (Appendix 8) In the forging die described in Supplementary Note 7, a width (W1) of the first side surface portion in the width direction may be equal to or greater than a width (W2) of the concave molding portion.

[0079] According to such a configuration, since the width of the first side surface portion is greater than the width of the concave molded portion, a wide region for increasing rigidity is ensured in the width direction, and the generation of stress during molding can be effectively suppressed.

[0080] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0081] 10...Forging mold 121…Type 1 122…2nd type 14…Holder 161, 162...Fixing members 18…Lower mold 20…Upper mold 22…molding surface 24...Holding surface 28...Concave molded part 30…Fixing groove 321, 322…Side C…Molded product

Claims

1. A forging die including a lower die and an upper die movable in a vertical direction relative to the lower die, wherein a first die which is one of the lower die and the upper die, and a second die which is the other of the lower die and the upper die each have a molding surface, the molding surface of the first die and the molding surface of the second die face each other, and each of the first die and the second die is fixed to a holder by a fixing member, At least the first type is a concave molding portion recessed in the molding surface in accordance with the shape of a molded product; a holding surface that comes into contact with a support surface of the holder that intersects with a moving direction of the upper die; A side surface connecting an outer edge of the molding surface and an outer edge of the holding surface; Equipped with The side surface includes a first side surface portion that is continuous with the outer edge portion of the molding surface; A second side portion connected to the outer edge portion of the holding surface; A forging die comprising a fixing groove portion provided between the first side portion and the second side portion, recessed horizontally relative to the first side portion and the second side portion, and into which the fixing member engages.

2. The forging die according to claim 1, The fixing groove has a groove depth D in the horizontal direction, the concave molding portion has an end molding groove closest to the side surface having the fixing groove portion, A forging die, wherein the groove depth and a molding surface length L, which is the distance from the end molding groove to the side surface, satisfy the relationship D / L≦0.

229.

3. The forging die according to claim 1, the concave molding portion has an end molding groove closest to the side surface having the fixing groove portion, A forging die, in which a first distance H1, which is the distance between the end of the first side portion that is farthest from the molding surface and the molding surface in the movement direction of the upper die, and a second distance H2, which is the distance from the molding surface to the deepest portion of the end molding groove, satisfy the relationship H1 / H2 ≧ 0.

53.

4. The forging die according to claim 1, The fixing groove has a bottom portion farthest from the side surface in a groove depth direction, A forging die, wherein in the groove depth direction, the height of the first side portion relative to the bottom portion is equal to or greater than half the height of the second side portion relative to the bottom portion.

5. The forging die according to claim 1, The fixing groove has a bottom portion farthest from the side surface in a groove depth direction, A forging die, wherein in the groove depth direction, a height of the first side portion relative to the bottom portion and a height of the second side portion relative to the bottom portion are the same.

6. In the forging die according to claim 3, A forging die, wherein the first distance H1 and the second distance H2 satisfy a relationship of H1 ≧ H2 in the movement direction of the upper die.

7. The forging die according to claim 1, A forging die, wherein the first side portion extends in a width direction which is a horizontal direction perpendicular to a groove depth direction of the fixing groove portion and perpendicular to a movement direction of the upper die.

8. The forging die according to claim 7, A forging die, wherein the width of the first side portion in the width direction is equal to or greater than the width of the concave molding portion.

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