Method of manufacturing press die

Abstract

To provide a manufacturing technique with which individual differences or artificial errors hardly occur in a press die comprising a hardened part.SOLUTION: In Fig. 3(a), a first intermediate product 31 is obtained. The first intermediate product 31 includes a soft bow cross-sectional part 11a. In Fig. 3(b), a second intermediate product 32 including a cut surface 14 is obtained by cutting off the soft bow cross-sectional part 11a. In Fig. 3(c), a padding part 15 is formed on the cut surface 14. In Fig. 3(e), a press die 10 is obtained by removing an excess thickness (Fig. 3(c), sign 16).SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a manufacturing technique for a press die provided with a partially hardened portion.

Background Art

[0002] Press dies are used for drawing, cutting, and bending blank materials. The blank material is a flat metal plate and is sufficiently hard. Therefore, when the press work is repeated, the corners and convex portions of the press die wear out earlier than other surfaces (general surfaces).

[0003] As one of the countermeasures, it has conventionally been practiced to partially build up a hardened portion having a higher hardness than the general surface at the corners (for example, see Patent Document 1 (FIG. 2) in the case of cutting).

[0004] Patent Document 1 will be described with reference to the following figures. FIGS. 11(a) to (d) are diagrams for explaining a conventional method for manufacturing a press die. The die base material 101 is prepared by subjecting a block of spheroidal graphite cast iron to cutting. This base material 101 is provided with a notch 102 having a triangular cross-section at the corners by cutting.

[0005] In FIG. 11(a), a base material 104 is attached to the cut surface 103 of the notch 102. In FIG. 11(b), high-speed steel 105 is built-up welded to the base material 104.

[0006] In FIG. 11(c), the built-up welded high-speed steel 105 is shaped by machining. In FIG. 11(d), the shaped high-speed steel 105 is heated with a halogen lamp 106. By performing heating and cooling, the high-speed steel 105 is heat-treated.

[0007] As described above, a press die 100 is provided in which high-speed steel 105 is attached to the corners of a base material 101 made of spheroidal graphite cast iron. High-speed steel 105 has the advantage of being significantly harder and more wear-resistant than spheroidal graphite cast iron.

[0008] However, the conventional press die 100 has the following problems. In FIG. 11(a), the notch 102 with a triangular cross-section is formed by a person, an NC machine tool (machining center), a milling machine, or the like. When formed by a person, due to individual differences, over-cutting or under-cutting will inevitably occur. When using an NC machine tool (machining center), a milling machine, or the like, human errors may occur during data input. Due to these errors, over-cutting or under-cutting will inevitably occur.

[0009] In FIG. 11(a), when h is too large, that is, in the case of over-cutting, the required amount of high-speed steel 105 increases. High-speed steel 105 is more expensive than the die base material 101. As a result, the manufacturing cost of the press die 100 increases. Since the cut base material becomes waste material, it is not environmentally preferable. In FIG. 11(a), when h is too small, that is, in the case of under-cutting, the amount of high-speed steel 105 decreases, and the wear resistance performance deteriorates.

[0010] However, not only for this trimming part (the notch 102 to be cut), but also for the press part that forms the design line, contour, concave-convex shape, and outer shape, in the situation where cost reduction of manufacturing and improvement of wear resistance performance are required, a manufacturing technology with less individual differences or human errors is required. However, in the situation where cost reduction of manufacturing and maintenance of wear resistance performance are required, a manufacturing technology with less individual differences or human errors is required.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] The present invention aims to provide a manufacturing technique in a press mold having a partially cured portion, which is less likely to cause individual differences or human errors.

Means for Solving the Problems

[0013] The invention according to claim 1 is a press mold manufacturing method for manufacturing a press mold including a base material and a cured portion locally provided on the base material, wherein the base material has a flat first surface and a flat second surface different from the first surface, the cured portion is provided between the first surface and the second surface and is composed of a hard bow cross-sectional portion having a bow shape with a chord in its cross section, the base material further has a soft bow cross-sectional portion having the same shape as the hard bow cross-sectional portion, a first processing step of obtaining a first intermediate product including the soft bow cross-sectional portion by processing the base material into a shape following the press mold; a second processing step of obtaining a second intermediate product including a cut surface by cutting out the soft bow cross-sectional portion from the first intermediate product; a third processing step of obtaining a third intermediate product including a build-up portion having a cross-sectional shape with excess material added to the soft bow cross-sectional portion by building up the cut surface of the second intermediate product with a material harder than the base material; and a fourth processing step of obtaining the press mold by cutting off the excess material from the build-up portion of the third intermediate product, thereby providing a press mold manufacturing method.

[0014] The invention according to claim 2 is the press mold manufacturing method according to claim 1, when the press mold is defined by a wire frame, the wire frame including vertices that are points on a screen, ridge lines connecting two of the vertices with a straight line or a curve, wires formed by connecting a plurality of the ridge lines in series, and a skeletal structure composed of a plurality of the wires, a vertex existing at the joint of a linear ridge line passing through the first surface and a curved ridge line connected to the linear ridge line is defined as a first inflection point, and a vertex existing at the joint of a linear ridge line passing through the second surface and the curved ridge line connected to the linear ridge line is defined as a second inflection point, The chord of the bow shape is defined by a straight line connecting the first inflection point and the second inflection point, which is characterized in that.

[0015] The invention according to claim 3 is the press die manufacturing method according to claim 1, wherein In the cross-sectional view of the press die, a point at one end of the first surface and changing from a straight line to a curve is defined as the first inflection point, and a point at one end of the second surface and changing from a straight line to a curve is defined as the second inflection point. The chord of the bow shape is defined by a straight line connecting the first inflection point and the second inflection point, which is characterized in that.

[0016] The invention according to claim 4 is the press die manufacturing method according to claim 1, wherein The base material is made of carbon steel for mechanical structures, and the hardened part is made of high-speed tool steel, which is characterized in that.

[0017] The invention according to claim 5 is the press die manufacturing method according to claim 1, wherein When the maximum thickness of the soft bow cross-sectional part is less than a predetermined value, a groove is formed in the cut surface, and a part of the hardened part is accommodated in this groove, which is characterized in that.

[0018] The invention according to claim 6 is the press die manufacturing method according to claim 1, wherein The hardened part is an island-shaped hardened part arranged in a dot shape on the cut surface, which is characterized in that.

[0019] The invention according to claim 7 is the press die manufacturing method according to claim 1, wherein In the hardened part, two hard bow cross-sectional parts are integrally formed like the nodules of a puffer fish, which is characterized in that.

[0020] The invention according to claim 8 is the press die manufacturing method according to claim 1, wherein The surplus material includes an overhanging part protruding from the hem of the soft bow cross-sectional part to the first surface and the second surface, which is characterized in that.

[0021] The invention according to claim 9 is a method for manufacturing a press die according to claim 2, wherein the cut surface is a ruled surface formed on the wire frame, and in the second processing step, processing is performed based on ruled surface processing data created based on the ruled surface.

[0022] The invention according to claim 10 is a method for manufacturing a press die according to claim 9, wherein the build-up is formed based on build-up data created by adding excess material to the soft bow cut surface portion formed on the wire frame.

[0023] The invention according to claim 11 is a method for manufacturing a press die according to claim 10, wherein the build-up data is stored in a control unit, and build-up welding is performed based on the build-up data stored in the control unit.

Advantages of the Invention

[0024] In the invention according to claim 1, the first intermediate product obtained in the first processing step has the same shape as the press die that is the final product. That is, the first intermediate product has a soft bow cut surface portion between a flat first surface and a flat second surface. The boundary between the first and second surfaces and the soft bow cut surface portion can be visually recognized. In manual cutting, once this boundary is reached, cutting can be terminated, so over-cutting or under-cutting does not occur. That is, since the boundary is clear, problems due to individual differences do not occur.

[0025] Also, simple NC data can be created using the data of the surface (machined surface) of the first and second surfaces and the soft bow cut surface portion. In cutting using an NC machine tool (machining center), a milling machine, etc. using this NC data, human errors are less likely to occur, and by computer-managing the data of the surface (machined surface), it is possible to stabilize the cutting amount and the build-up amount and stabilize the quality. Also, the quality of the dies when manufacturing a plurality of the same dies can be ensured. Therefore, according to the present invention, in a press die having a partially cured portion, a manufacturing technique capable of stabilizing quality and being less likely to cause individual differences or human errors is provided.

[0026] Furthermore, since the first intermediate product has the same shape as the press die which is the final product, the shape of the first intermediate product is uniquely determined, and the manufacture of the first intermediate product becomes easy.

[0027] In the invention according to claim 2, the press die is shown by a wireframe in CAD, and the string of the bow related to the soft bow cross-sectional part is defined by a straight line connecting the first inflection point and the second inflection point. As a result, the cross-section is uniquely determined, and there is no room for individual differences or human errors to occur.

[0028] In the invention according to claim 3, the press die is shown in a cross-sectional view, and the string of the bow related to the soft bow cross-sectional part is defined by a straight line connecting the first inflection point and the second inflection point. As a result, the cross-section is uniquely determined, and there is no room for individual differences or human errors to occur.

[0029] In the invention according to claim 4, the base material is made of carbon steel for mechanical structures, and the cured part is made of high-speed tool steel. Since carbon steel for mechanical structures is softer and more ductile than high-speed tool steel, a hardness (for example, HRC60 or more) that can withstand the wear associated with press working sufficiently without heat treatment can be obtained.

[0030] In the invention according to claim 5, a groove is formed in the cross-section, and a part of the cured part is accommodated in this groove. Since a part of the accommodated cured part exhibits an anchor effect, the bonding strength of the cured part to the base material is increased.

[0031] In the invention according to claim 6, the cured part is an island-shaped cured part arranged in a dot shape on the cross-section. Partial curing can also be performed with so-called island-shaped protrusions.

[0032] In the invention according to claim 7, two hard bow cross-sectional parts are combined and formed on the cured part like the tubercles of a puffer fish. Even if the radius of curvature of the hard bow cross-sectional part is small and the two hard bow cross-sectional parts are close to each other, the cured part can be easily formed by combining the two.

[0033] In the invention according to claim 8, the surplus material includes the projecting portions projecting to the first and second surfaces. Due to the presence of the projecting portions, in the fourth processing step, the boundary between the hardened portion and the base material can be finished into a smooth continuous surface without steps.

[0034] In the invention according to claim 9, in the second processing step, processing is performed based on the ruled surface processing data created based on the ruled surface. When the ruled surface processing data is created, a high-hardness material can be build-up welded by laser welding, gas welding, or arc welding. The welding can be performed by a composite processing machine such as a human, a robot, or a 3D printer.

[0035] In the invention according to claim 10, the build-up is formed based on the build-up data created by adding surplus material to the soft bow cross-sectional portion formed on the wire frame. Even for a press die with a complex shape, automation of the build-up welding becomes possible.

[0036] In the invention according to claim 11, the build-up data is stored in the control unit, and the build-up welding is performed based on the build-up data stored in this control unit. Since it is based on the build-up data, precise build-up welding is performed. Because it is precise, wasteful use of expensive high-hardness materials is corrected, and the manufacturing cost can be optimized.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

BEST MODE FOR CARRYING OUT THE INVENTION

[0038] Embodiments of the present invention will be described below with reference to the accompanying drawings.

EXAMPLE

[0039] [Press Die] As shown in FIG. 1, the press die 10 is composed of a base material 11 that occupies most of it and a hardened portion 20 that is locally provided on the base material 11. The hardened portion 20 is generally provided at the corners or convex portions of the press die 10.

[0040] Generally, a plurality of hardened portions 20 are provided on one press die 10. When it is necessary to distinguish locations, they are distinguished by adding English letters, such as a certain hardened portion 20A and the adjacent hardened portion 20B. The basic shape of the hardened portion 20 will be described with reference to FIG. 2.

[0041] [Base Material] As shown in FIG. 2, the base material 11 has a flat first surface 12 and a flat second surface 13 different from the first surface 12. The material of the base material 11 will be described later.

[0042] [Hardened Portion] The hardening part 20 is provided between the first surface 12 and the second surface 13, and is composed of a hard bow cross-sectional part 21 whose cross-section presents a bow shape including a chord. T is the maximum thickness of the hard bow cross-sectional part 21. The material of the hardening part 20 will be described later. A method for manufacturing the press mold 10 having the above form will be described in detail with reference to FIG. 3.

[0043] [Press Mold Manufacturing Method] FIG. 3(a) shows the first processing step. In this first processing step, the base material 11 is processed into a shape following the press mold 10 shown in FIG. 2 to obtain a first intermediate product 31.

[0044] This first intermediate product 31 has a soft bow cross-sectional part 11a at the corners. This soft bow cross-sectional part 11a has the same shape as the hard bow cross-sectional part (reference numeral 21 in FIG. 2). Since it has a shape following the press mold, the data of the press mold (reference numeral 10 in FIG. 2), which is the final product, can be used as it is. Therefore, the manufacture of the first intermediate product 31 becomes easy.

[0045] FIG. 3(b) shows the second processing step. In this second processing step, the soft bow cross-sectional part 11a is cut off from the first intermediate product 31. As a result, a second intermediate product 32 including a cut surface 14 can be obtained.

[0046] FIG. 3(c) shows the third processing step. In this third processing step, a build-up part 15 is formed on the cut surface 14. The build-up part 15 has a shape obtained by adding surplus material 16 to the soft bow cross-sectional part 11a. In addition, the build-up part 15 is composed of a material having a higher hardness than the base material.

[0047] [Material of the Base Material] The base material is preferably carbon steel for machine structural use defined in JIS G 4051 or equivalent carbon steel. Carbon steel for machine structural use is cheaper than high-speed tool steel, has flexible ductility, and has a hardness (for example, HRC60) that can withstand the wear of press working even without heat treatment. HRC means Rockwell C scale hardness. Among carbon steels for machine structural use, S10C to S58C are standardized, but S50C with a C (carbon) component of 0.50% is excellent in terms of strength and hardness and is suitable for the base material.

[0048] [Material with a higher hardness than the base material] As the material having a higher hardness than the base material, high-speed tool steel defined in JIS G 4403 or equivalent steel is preferable. The high-speed tool steel can have a hardness higher than S50C after heat treatment, and can be expected to be about HRC65. This is because the wear resistance is improved as the hardness increases.

[0049] [Build-up welding] For build-up welding, arc welding using a welding rod, laser welding using welding powder (powder of high-speed tool steel or equivalent steel, the same applies hereinafter), etc. can be adopted. The latter (laser welding using welding powder) is more preferable. The welding powder is neatly arranged on the cut surface (ruled surface) and melted by the heat of the laser (plasma arc heat). The amount of welding powder used can be optimized. Compared with excessive use, the amount of welding powder used can be reduced, and the amount of carbon dioxide generated can be reduced. Therefore, laser welding using welding powder enables production (manufacturing) suitable for the environment, which is more preferable. Laser welding using welding powder will be described later with reference to FIG. 9.

[0050] [Overhanging portion] Although it is optional to provide, as shown in FIG. 3(d), the surplus material 16 includes an overhanging portion 17 that overhangs to the second surface 13 (and the first surface 12). The overhanging length L of the overhanging portion 17 may be about 0.1 to 0.5 mm. The thickness of the overhanging portion 17 may be the thickness of the first layer when the welding powder is laminated.

[0051] Due to the presence of the overhanging portion 17, in the fourth processing step shown in FIG. 3(e), the boundary between the hardened portion 20 and the base material 11 can be finished into a smooth continuous surface without steps.

[0052] In addition, due to reasons such as insufficient amount of build-up welding, a V-shaped depression (notch) may be formed at the boundary between the hard bow fracture surface portion 21 and the second surface 13 (or the first surface 12). This V-shaped notch will become a starting point for fatigue fracture if left unattended, which is not preferable. In this regard, by providing the overhanging portion 17, there is also an advantage that the occurrence of the notch can be more reliably prevented.

[0053] Fig. 3(e) shows the fourth processing step. In this fourth processing step, the excess material 16 shown in Fig. 3(c) is removed to obtain the press die 10. This press die 10 has the same shape as Fig. 2.

[0054] The first intermediate product 31 shown in Fig. 3(a) has the same shape as the press die (Fig. 2, reference numeral 10) which is the final product. That is, the first intermediate product 31 has a soft bow fracture surface portion 11a between the flat first surface 12 and the flat second surface 13, and since the boundary between the first and second surfaces 12, 13 and the soft bow fracture surface portion 11a is an inflection point where the straight line changes to a curve, it is visible. In manual cutting, once this boundary is reached, the cutting can be terminated, so there will be no over-cutting or under-cutting. That is, since the boundary is clear, problems due to individual differences do not occur.

[0055] Also, simple NC data can be created using the data of the surface (machined surface) of the first and second surfaces 12, 13 and the soft bow fracture surface portion 11a. In cutting using an NC machine tool (machining center), a milling machine, etc. using this NC data, human errors are less likely to occur, and by managing the data of the surface (machined surface) by a computer, the cutting amount and the build-up welding amount can be stabilized, and the quality can be stabilized. Also, the quality of the dies can be ensured when manufacturing a plurality of the same dies. Therefore, according to the present invention, in the press die 10 provided with the partially hardened portion 20, a manufacturing technique is provided in which individual differences or human errors are less likely to occur and the quality can be stabilized.

[0056] Incidentally, the identification or setting of the cutting plane 14 described in Fig. 3(b) is important. This identification or setting can be performed in either a wireframe by CAD (computer-aided design) or a general drawing. These will be described in order below.

[0057] [Wireframe] The wireframe will be described based on Figs. 4(a) to (e), and the ruled surface corresponding to the cutting plane will be described based on (f) and (g). Note that the ruled surface is one of the CAD terms, denoted in English as "ruled surface", and means a surface surrounded by a specific group of ridge lines (the definition of the ridge line will be described later). Since the ridge line appears on the surface, the ruled surface is the same as the ruled surface.

[0058] Fig. 4(a) shows the vertex 35. This vertex 35 is a point set on the CAD screen. Fig. 4(b) shows the straight ridge line 36. This ridge line 36 is a line connecting two vertices 35 in a straight line. Fig. 4(c) shows the curved ridge line 37. This ridge line 37 is a line connecting two vertices 35 in a curve. The curve is defined by the radius of curvature R.

[0059] Fig. 4(d) shows the wire 38. The wire 38 is a broken line or a meandering line in which straight ridge lines 36, curved ridge lines 37, or a combination of straight ridge lines 36 and curved ridge lines 37 are connected in series. Fig. 4(e) shows the wireframe 39. The wireframe 39 is a skeletal structure in which a plurality of wires 38 are arranged in a grid pattern.

[0060] [Ruled surface] In Fig. 4(d), the vertical ridge line 36 is reinterpreted as the straight ridge line 36v passing through the first surface, and the horizontal ridge line 36 is reinterpreted as the straight ridge line 36h passing through the second surface. Then, the vertex 35 existing at the joint between the straight ridge line 36v passing through the first surface and the curved ridge line 37 connected to this straight ridge line 36v is defined as the first inflection point 41. Similarly, a vertex 35 existing at the joint between a linear ridge line 36h passing through the second surface and a curved ridge line 37 connected to this linear ridge line 36h is defined as a second inflection point 42.

[0061] Next, as shown in FIG. 4(f), the first inflection point 41 and the second inflection point 42 are connected by a line 43. This line 43 corresponds to the chord of the bow of the soft bow cut surface portion 11a shown in FIG. 3(a) and also corresponds to the cut surface 14 shown in FIG. 3(b). When the two-dimensional display of FIG. 4(f) is changed to a three-dimensional display, it becomes FIG. 4(g).

[0062] In FIG. 4(g), the surface surrounded by the line 43 connecting the first inflection point 41 and the second inflection point 42, the wires 38, 38 orthogonal (including substantially orthogonal) to this line 43, and the rear line 44 becomes a ruled surface 45. This ruled surface 45 corresponds to the cut surface 14.

[0063] As described above, the press die is shown by a wire frame 39 by CAD, and the chord of the bow related to the soft bow cut surface portion is defined by the line 43 connecting the first inflection point 41 and the second inflection point 42. As a result, the cut surface 14 is uniquely determined, and there is no room for individual differences or human errors to occur.

[0064] [General drawing] FIG. 5 is a reproduced view of FIG. 2 (however, the reference signs are different), and is a general drawing showing a cross section of the main part of the press die. Based on such a FIG. 5, the cut surface 14 can be specified or set. In FIG. 5, a point at one end of the first surface 12 where the line changes from straight to curved is defined as the first inflection point 41. Similarly, a point at one end of the second surface 13 where the line changes from straight to curved is defined as the second inflection point 42. Next, the first inflection point 41 and the second inflection point 42 are connected by a line 43. This line 43 corresponds to the chord of the bow and also corresponds to the cut surface 14.

[0065] Therefore, the method of the present invention can be easily implemented in both the use of CAD and the use of general drawings.

[0066] Incidentally, in FIG. 2, when the maximum thickness T of the hard bow cross-sectional portion 21 is equal to or less than a predetermined value (for example, 1.0 mm), the cured portion 20 may peel off from the base material 11. The countermeasure at that time will be described based on FIGS. 6(a) and 6(b).

[0067] [Groove provided on the cutting surface] As shown in FIG. 6(a) or FIG. 6(b), when the maximum thickness T of the hard bow cross-sectional portion 21 (correctly, the soft bow cross-sectional portion 11a) is less than the predetermined value, a groove 47 like a gutter is formed in the cut surface 14, and a part of the cured portion 20 is accommodated in this groove 47. Since a part of the accommodated cured portion 20 exerts an anchor effect, the bonding strength of the cured portion 20 to the base material 11 is increased.

[0068] Note that the cross-sectional shape of the groove 47 is arbitrary. However, as shown in FIG. 6(a), it may be an arcuate cross-section. If it is an arcuate cross-section, the groove 47 can be easily formed by machining. Alternatively, as shown in FIG. 6(b), the groove 47 may have a rectangular cross-section. Although machining the rectangular cross-section is a bit troublesome, the anchor effect is stronger than that of the arcuate cross-section. Therefore, considering the cost-effectiveness, the cross-sectional shape of the groove 47 may be determined.

[0069] An island-shaped protrusion 48 is provided on the press die 10 shown in FIG. 1. The present invention can also be applied to this island-shaped protrusion 48.

[0070] [Island-shaped cured portion] FIG. 7(a) is an enlarged view of part 7a in FIG. 1. As shown in FIG. 7(a), the island-shaped protrusion 48 is made into an island-shaped cured portion 20C according to the present invention. FIG. 7(b) is a cross-sectional view taken along line b-b in FIG. 7(a), and the island-shaped cured portion 20C is a hard bow cross-sectional portion 21 formed between the first surface 12 and the second surface 13. Therefore, the cured portion (reference numeral 20 in FIG. 1) according to the present invention may be an island-shaped protrusion in addition to the rib.

[0071] Also, in FIG. 1, the cured portion 20B adjacent to a certain cured portion 20A may be arranged at a very close position. That is, as shown in Fig. 8(a), a cured portion 20B adjacent to a certain cured portion 20A is arranged at a very close position. In this case, the form of Fig. 8(b) can be adopted.

[0072] [Hooded seal]] As shown in Fig. 8(b), in the cured portion 20, two hard bow cross-sectional portions 21 are integrally formed like the bumps of a hooded seal.

[0073] When adopting this example, in Fig. 8(a), among the two inflection points 41 and 42 of a certain cured portion 20A, the one farther from the adjacent cured portion 20B is defined as the first inflection point 41. Next, among the two inflection points 41 and 42 of the adjacent cured portion 20B, the one farther from a certain cured portion 20A is defined as the second inflection point 42. As shown in Fig. 8(b), the cutting surface 14 is specified by connecting the determined first inflection point 41 and second inflection point 42 with a straight line.

[0074] Compared with Fig. 8(a), in Fig. 8(b), two surfacing welds can be completed in one time. On the contrary, compared with Fig. 8(a), the amount of expensive welding powder increases in Fig. 8(b). Therefore, when the two cured portions 20 are separated, the form of Fig. 8(a) is adopted, and when the two cured portions 20 are very close to each other, it is recommended to adopt the form of Fig. 8(b).

[0075] [Surfacing welding device]] The surfacing welding device 50 includes, for example, a welding robot 52 equipped with a welding gun 51, a powder metering feeder 54 that supplies a predetermined amount of welding powder 53 to the welding gun 51, a high-voltage power supply 56 that supplies electrical energy for the plasma jet 55 emitted by the welding gun 51 to the welding gun 51, a gas container 58 that supplies argon gas for the shielding gas 57 emitted by the welding gun 51, and a control unit 59 that controls the welding robot 52, the welding gun 51, the powder metering feeder 54, the high-voltage power supply 56, and the gas container 58.

[0076] The control unit 59 supplies an appropriate amount of welding powder 53, argon gas, and electric energy to the welding gun 51. A plasma jet 55, the welding powder 53, and a shielding gas 57 are ejected from the welding gun 51. By this ejection, the welding powder 53 is layered on the cutting surface 14.

[0077] The laminated welding powder 53 is sequentially melted by the plasma heat. During this time, since it is shielded by the shielding gas 57, the welding powder 53 is not oxidized, and a sound hardened portion 20 is formed.

[0078] The press die manufacturing method described based on FIGS. 3(a) to 3(e) is more preferably implemented based on ruled surface machining data and build-up data. Therefore, the ruled surface machining data and the build-up data will be described based on FIG. 10.

[0079] [Ruled Surface Machining Data] In step number (hereinafter, ST) 01 of FIG. 10, a wireframe as shown in FIG. 4(e) is created. In ST02, a ruled surface as shown in FIG. 4(g) is set. Based on this ruled surface, ruled surface machining data is created (ST03). Based on this ruled surface machining data, a ruled surface (i.e., a cutting surface) is formed (ST04).

[0080] When the ruled surface machining data is created, a high-hardness material can be build-up welded by laser welding, gas welding, or arc welding. Welding has the advantage that it can be performed by a composite processing machine such as a human, a robot, or a 3D printer.

[0081] [Build-up Data] Based on the ruled surface machining data created in ST03, build-up data is created (ST05). Based on this build-up data, build-up welding in the form shown in FIG. 3(c) is performed (ST06). This build-up is machined and finished (ST07).

[0082] That is, the build-up is formed based on build-up data created by adding excess material to the soft bow cross-sectional part formed on the wire frame. Even for a press die with a complex shape, automation of build-up welding becomes possible.

[0083] This build-up data is stored in the control unit 59 shown in FIG. 9, and build-up welding is performed based on the build-up data stored in this control unit 59. Since it is based on build-up data, precise build-up welding is performed. Because it is precise, wasteful use of expensive high-hardness materials is corrected, and the manufacturing cost can be optimized.

Industrial Applicability

[0084] The present invention is suitable for a technique for manufacturing a press die including a base material and a hardened part locally provided on the base material.

Explanation of Signs

[0085] 10... Press die, 11... Base material, 11a... Soft bow cross-sectional part, 12... First surface, 13... Second surface, 14... Cutting surface, 15... Build-up part, 16... Excess material, 17... Overhanging part, 20... Hardened part, 20A... A certain hardened part, 20B... Adjacent hardened part, 20C... Island-shaped hardened part, 21... Hard bow cross-sectional part, 31... First intermediate product, 32... Second intermediate product, 33... Third intermediate product, 35... Vertex, 36... Straight ridge line, 37... Curved ridge line, 38... Wire, 39... Wire frame, 41... First inflection point, 42... Second inflection point, 43... Connecting line (line connecting the first and second inflection points), 45... Ruled surface, 47... Groove, 59... Control unit, T... Maximum thickness (maximum thickness of the soft bow cross-sectional part, also the maximum thickness of the hard bow cross-sectional part).

Claims

1. A method for manufacturing a press die comprising: a base material and a hardened portion locally provided on the base material, the method comprising the steps of: the base material has a flat first surface and a flat second surface different from the first surface; The hardened portion is provided between the first surface and the second surface, and is composed of a hard bow cross-section portion having a cross section in the shape of a bow including a string; The base material further has a soft bow cross-section having the same shape as the hard bow cross-section, A first processing step of processing the base material into a shape conforming to the press die to obtain a first intermediate product including the soft bow cross section; A second processing step of obtaining a second intermediate product including a cut surface by cutting the soft bow cross section from the first intermediate product; A third processing step of providing a padding portion on the cut surface of the second intermediate product with a material having a higher hardness than the base material to obtain a third intermediate product including a padding portion having a cross-sectional shape in which excess padding is added to the soft bow cross-sectional portion; and a fourth processing step of obtaining the press die by cutting away excess metal from the padding portion of the third intermediate product.

2. The press die manufacturing method according to claim 1, When the press die is shown by a wire frame, and this wire frame is defined by vertices which are points on a screen, ridge lines each connecting two of the vertices by a straight line or a curved line, wires connecting a plurality of the ridge lines in series, and a skeleton structure constituted by a plurality of the wires, a vertex at a joint between a straight edge line passing through the first surface and a curved edge line connected to the straight edge line is defined as a first inflection point, and a vertex at a joint between a straight edge line passing through the second surface and a curved edge line connected to the straight edge line is defined as a second inflection point, The press die manufacturing method, wherein the bowstring is determined by a straight line connecting the first inflection point and the second inflection point.

3. The press die manufacturing method according to claim 1, In a cross-sectional view of the press die, a point at one end of the first surface where the straight line changes to a curved line is defined as a first inflection point, and a point at one end of the second surface where the straight line changes to a curved line is defined as a second inflection point, The press die manufacturing method, wherein the bowstring is determined by a straight line connecting the first inflection point and the second inflection point.

4. The press die manufacturing method according to claim 1, A method for manufacturing a press die, wherein the base material is made of carbon steel for mechanical construction, and the hardened portion is made of high-speed tool steel.

5. The press die manufacturing method according to claim 1, A method for manufacturing a press die, characterized in that when the maximum thickness of the soft bow cross-section portion is less than a predetermined value, a groove is formed on the cut surface and a portion of the hardened portion is accommodated in this groove.

6. The press die manufacturing method according to claim 1, A press die manufacturing method, characterized in that the hardened portion is an island-shaped hardened portion arranged in a dot-like pattern on the cut surface.

7. The press die manufacturing method according to claim 1, A method for manufacturing a press die, characterized in that the hardened portion has two rigid arch-shaped cross-sectional portions formed therein, like the humps of a Bactrian camel.

8. The press die manufacturing method according to claim 1, A press die manufacturing method, characterized in that the excess material includes an overhanging portion overhanging from the bottom of the soft bow cross-section portion to the first surface and the second surface.

9. The press die manufacturing method according to claim 2, A press die manufacturing method characterized in that the cutting surface is a ruled surface formed on the wire frame, and in the second processing step, processing is performed based on ruled surface processing data created based on the ruled surface.

10. The press die manufacturing method according to claim 9, The press die manufacturing method according to the present invention, characterized in that the padding is formed based on padding data created by adding excess padding to the soft bow cross-section portion formed on the wire frame.

11. The press die manufacturing method according to claim 10, The press die manufacturing method is characterized in that the deposition data is stored in a control unit, and deposition welding is performed based on the deposition data stored in the control unit.

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