Mold, mold manufacturing method, and mold inspection method

Abstract

A mold (10) is composed of a die (20) and a punch (60). The die (20) has a die side wall portion (22) and a die flange portion (24). A portion where the die flange portion (24) and the die side wall portion (22) intersect is called a die shoulder portion (27). When the portion of the die (20) excluding the die shoulder portion (27) is called a die main body portion (28), the boundary between the die main body portion (28) and the die shoulder portion (27) is a straight line (31). The outer surface of the die shoulder portion (27) is a curved line (32) that is convex outward. One end of the straight line (31) is connected to one end of the curved line (32) and the other end of the straight line (31) is connected to the other end of the curved line (32). The die shoulder portion (27) is composed of a die hardened portion (35) that is harder than the die main body portion (28).

Description

[Technical field]

[0001] The present invention relates to a die to be mounted on a press machine. [Background technology]

[0002] For example, in a car body manufacturing line, a metal plate called a blank is plastically processed by a press machine. Through plastic processing, a product with a desired three-dimensional shape is obtained. A die is used for the plastic processing.

[0003] Although dies are made of a material harder than a metal plate, when attempting to manufacture a large number of molded products, the surface gradually wears away. When this wear progresses to a certain depth, the die is repaired or replaced with a new die. During the time the die is repaired or replaced, plastic processing is suspended. This suspension reduces the productivity of molded products. The shorter the die life (the period between replacements), the lower the productivity, and the longer it is, the higher the productivity. Therefore, technology to extend the die life is required.

[0004] One known technique for extending the life of a mold is to form a hardened layer on the surface of the mold that is harder than the mold itself (see, for example, Patent Document 1 (FIG. 2)).

[0005] Patent Document 1 will be explained with reference to the following figure. FIG. 19 is a cross-sectional view of a conventional mold. 19, the mold 200 is made up of a mold body 201 called a base portion and a hardened layer 202 called a surface layer. The hardened layer 202 is made of a metal material harder than the mold body 201. The hardened layer 202 is formed on the entire molding surface of the mold body 201 .

[0006] According to Patent Document 1, since the hardened layer 202 is hard, the life of the mold 200 is extended, and the productivity of molded products is improved.

[0007] However, the cost of forming the hardened layer 202 on the mold body 201 is approximately proportional to the volume of the hardened layer 202 . In Patent Document 1, since the hardened layer 202 is formed on the entire molding surface of the mold body 201, the volume of the hardened layer 202 becomes large, and the cost of forming the hardened layer 202 becomes high. That is, the technique of Patent Document 1 has a drawback in that the manufacturing costs of the mold 200 are high.

[0008] In recent years, there has been a demand for cost reduction in vehicles, and as part of that, there has been a demand for cost reduction in the vehicle body, and as part of that, there has been a demand for reduction in the manufacturing cost of the die 100. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2016-137496 A Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a technique that can reduce the manufacturing costs of molds. [Means for solving the problem]

[0011] The invention according to claim 1 is a die comprising a die and a punch, which performs plastic working on a metal plate into a hat-shaped cross section, the die includes a die side wall portion extending along a movement axis of the punch, a die flange portion extending from the die side wall portion in a direction intersecting the movement axis of the punch, and a die top portion located at the back of the die side wall portion, the punch includes a punch side wall portion facing the die side wall portion, a punch flange portion facing the die flange portion, and a punch top portion facing the die top portion, The portion where the die flange portion and the die side wall portion intersect is called a die shoulder portion, and the portion of the die excluding the die shoulder portion is called a die main body portion. In a cross-sectional view, the boundary between the die body and the die shoulder is a straight line, the outer surface of the die shoulder is a curved line that is convex outward, one end of the straight line is connected to one end of the curved line, and the other end of the straight line is connected to the other end of the curved line, The die shoulder portion is made of a die hardened portion having a higher hardness than the die body portion. 、 A first hardened coating portion having a hardness higher than that of the die body portion is embedded in the die side wall portion, and one end of the first hardened coating portion is connected to the die hardened portion. There are.

[0012] The hat cross-sectional shape refers to a cross-sectional shape similar to that of hat steel defined in JIS G 3350, Light Gauge Steels for General Structure. Effect of the Invention

[0013] In the invention according to claim 1, the die shoulder of the metal mold is the part that is always subject to wear and the strongest pressure when bending a flat metal plate into a hat-shaped cross-section. Since the hardened portion is limited to the die shoulder, the volume of the hardened portion is very small. Since the volume of the hardened portion is very small, the cost of forming the hardened portion is very small. The reduction in the cost of forming the hardened portion reduces the manufacturing cost of the die. That is, the present invention provides a technique that can reduce the manufacturing costs of molds.

[0014] Moreover, stress is inevitably concentrated on the die shoulder. In the invention according to claim 1, the outer surface of the die shoulder is a curved line that is convex outwards. The corners are rounded to reduce stress concentration. As a result, the die of the invention is effective and has a longer life than conventional dies. In addition, the longer life and the elimination of unnecessary manufacturing not only reduce costs, but also provide a manufacturing process that is less impactful on the environment.

[0015] When a die is composed of a die body and a die shoulder, the boundary between the die body and the die shoulder is determined by design. This determination is important and requires a high level of technology. However, in the invention according to claim 1, since the outer surface of the die shoulder is a curved line, the boundary is uniquely determined by simply connecting one end of the curved line with the other end of a straight line. As a result, the boundary between the die body and the die shoulder can be easily determined based on the die data. Since the shape is easily determined, advanced technology is not required for the design of the die. In addition, if the wear of the die main body portion in the die sidewall portion is greater than that of the die hardened portion, the wear resistance of the die can be further increased by embedding a first coating hardened portion in the die sidewall portion, which has a harderness than the die main body portion, and connecting one end of this first coating hardened portion to the die hardened portion. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1(a) is a cross-sectional view of a mold according to the present invention, and FIG. 1(b) is an enlarged view of part b in FIG. [Diagram 2] 1(a) to 1(e) are diagrams illustrating a method for manufacturing a die. [Diagram 3] FIG. 1 is a diagram showing an example of a build-up welding apparatus. [Figure 4] 4(a) to 4(c) are views for explaining the function of the mold according to the present invention. [Diagram 5] 1(a) to 1(c) are views for explaining a first modified example of a mold according to the present invention. [Figure 6] 13(a) and 13(b) are diagrams illustrating further modifications of the first hardened coating portion. [Figure 7] 13(a) and 13(b) are views for explaining a second modified example of the mold according to the present invention. [Figure 8] 13(a) to 13(c) are diagrams illustrating a third modified example of the mold according to the present invention. [Figure 9] 9(a) to (e) are diagrams for explaining a fourth modified example of the mold according to the present invention, (c) is a view taken along the arrows 9c-9c in FIG. 8, (d) is a cross-sectional view taken along the line dd in FIG. 9, and (e) is a cross-sectional view taken along the line ee in FIG. 9. [Figure 10] 13(a) and 13(b) are diagrams illustrating modified examples of the third hardened coating portion. [Figure 11] 13(a) and 13(b) are diagrams for explaining a fifth modified example of the mold according to the present invention. [Figure 12] FIG. 13 is a diagram illustrating a sixth modified example of the mold according to the present invention. [Figure 13] FIG. 13 is a diagram illustrating a seventh modified example of the mold according to the present invention. [Figure 14] 1A to 1H are diagrams illustrating a wire frame and a ruled surface. [Figure 15] 1A and 1B are cross-sectional views of a main mold and a partial mold, and FIG. 1B is a cross-sectional view of the partial mold, and FIG. 1C is a diagram showing an example of a mold inspection device. [Figure 16] 13A and 13B are diagrams illustrating a modified example of the die hardening unit. [Figure 17] 13A to 13C are diagrams illustrating further modified examples of the die hardening section. [Figure 18] 13A to 13C are diagrams illustrating further modified examples of the die hardening section. [Figure 19] FIG. 1 is a cross-sectional view of a conventional mold. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. EXAMPLES

[0018] [Mold] 1(a), the mold 10 is composed of a die 20 and a punch 60. The mold 10 can plastically work a flat metal plate 12 into a hat-shaped cross-sectional shape.

[0019] [Thailand] The die 20 comprises a die side wall portion 22 extending along the punch movement axis 61, a die flange portion 24 extending from the die side wall portion 22 in a direction intersecting the punch movement axis 61, and a die top portion 26 located at the rear 25 of the die side wall portion 22.

[0020] [punch] The punch 60 includes a punch side wall portion 62 facing the die side wall portion 22 , a punch flange portion 64 facing the die flange portion 24 , and a punch top portion 66 facing the die top portion 26 .

[0021] [Die shoulder and die body] FIG. 1(b) is an enlarged view of part b in FIG. 1(a). As shown in FIG. 1( b ), the portion where the die flange portion 24 and the die side wall portion 22 intersect is called a die shoulder portion 27 . The portion of the die 20 excluding the die shoulder portion 27 is referred to as a die body portion 28 . That is, the die 20 is composed of a die body portion 28 and a die shoulder portion 27 .

[0022] In cross-sectional view, the boundary between the die body 28 and the die shoulder 27 is a straight line 31 . The outer surface of the die shoulder 27 is formed into an outwardly convex curved line 32 . One end of the straight line 31 and one end of the curved line 32 are connected via a first inflection point 33, and the other end of the straight line 31 and the other end of the curved line 32 are connected via a second inflection point .

[0023] [Die Design] The procedure for designing the die 20 will now be described. First, the curved line 32 is defined. Next, the die sidewall portion 22 extends from one end of the curved line 32 and the die flange portion 24 extends from the other end of the curved line 32 . Finally, the first inflection point 33 and the second inflection point 34 are connected by a straight line 31.

[0024] As a result of the above, the boundary between the die body 28 and the die shoulder 27 can be easily determined, making it extremely easy to design the die hardening portion 35 of the die 20, and reducing the design costs of the mold 10 having the die hardening portion 35.

[0025] [Die hardening section] The die shoulder 27 is formed of a die hardened portion 35 having a higher hardness than the die body 28 . The material with high hardness is preferably high-speed tool steel as specified in JIS G 4403 or an equivalent steel. High-speed tool steel has a hardness after heat treatment that is higher than S50C, and can be expected to have a hardness of about HRC60 to 65. This is because the higher the hardness, the better the wear resistance. HRC stands for Rockwell C scale hardness.

[0026] [Material of the die body] The material of the die body 28 is preferably carbon steel for machine construction as specified in JIS G 4051 or an equivalent carbon steel. Carbon steel for mechanical construction is cheaper than high-speed tool steel, has pliable ductility, and has a hardness (e.g., HRC25) that can withstand the wear caused by press processing even without heat treatment. For carbon steel for machine structure, S10C to S58C are standardized, but S50C, which has a C (carbon) content of 0.50%, is superior in strength and hardness. S50C is more suitable for the die body 28.

[0027] [Die manufacturing] A method for manufacturing the die 20 will be described with reference to FIGS. 2(a) to 2(e). The first processing step is shown in FIG. 2(a). In this first processing step, a die blank 41 is processed into a shape following the die 20 shown in FIG. 1(b) to obtain a first intermediate product .

[0028] The first intermediate product 42 has a soft bow cross section 43 at a corner. The soft bow cross section 43 has the same shape as the die hardened portion (FIG. 1(b), reference numeral 35). Since the shape is modeled after the die (FIGS. 1(a) and (b), reference numeral 20), the data of the mold (FIG. 1(a), reference numeral 10), which is the final product, can be used as is. This makes it easy to manufacture the first intermediate product 42.

[0029] The second processing step is shown in FIG. 2(b). In this second processing step, the soft bow cross section portion 43 is cut out from the first intermediate product 42. As a result, a second intermediate product 44 including a cut surface 44a can be obtained.

[0030] The third processing step is shown in FIG. 2(c). In this third processing step, a padding portion 45 is formed on the cut surface 44a to obtain a third intermediate product 46. The padding portion 45 has a shape in which an excess pad 45a is added to the soft bow cross section portion 43.

[0031] [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 below), etc. can be used. The latter (laser welding using welding powder) is more preferable. The welding powder is arranged in an orderly manner on the cutting surface (ruled surface described later) and melted by the heat of the laser (plasma arc heat). The amount of welding powder used can be optimized.

[0032] Compared to 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 environmentally friendly production (manufacturing), which is more preferable. Laser welding using welding powder will be described next.

[0033] [Welding equipment] As shown in FIG. 3, the build-up welding apparatus 50 includes, for example, a welding robot 52 equipped with a welding gun 51, a powder supplying machine 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 to the welding gun 51 for the plasma jet 55 emitted by 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 supplying machine 54, the high-voltage power supply 56, and the gas container 58.

[0034] Appropriate amounts of welding powder 53, argon gas, and electrical energy are supplied to welding gun 51 by control unit 59. Plasma jet 55, welding powder 53, and shielding gas 57 are sprayed from welding gun 51. Due to this spraying, welding powder 53 is layered on cut surface 44a.

[0035] The accumulated welding powder 53 is melted in sequence by the plasma heat. During this time, the welding powder 53 is shielded by the shielding gas 57, so that the welding powder 53 does not oxidize and a sound build-up portion 45 is formed.

[0036] It is acceptable to use a multi-tasking machine such as a 3D (three-dimensional) printer. By using a multi-tasking machine, the manufacturing time can be shortened and the hardened portion can be formed by stacking hard materials. By using a multi-tasking machine, it is possible to automate the process of cutting off the excess material 45a after the hardened portion is formed.

[0037] [Protruding part] Preferably, as shown in FIG. 2(d), the excess pad 45a includes a protruding portion 45b that protrudes to the outer surface of the die body portion 28. The extension length L of the extension portion 45b may be about 0.1 to 5.0 mm.

[0038] Due to the presence of the overhanging portion 45b, the boundary between the die hardened portion 35 and the die main body portion 28 can be finished into a smooth continuous surface without steps in the fourth processing step shown in FIG. 2(e).

[0039] In addition, due to an insufficient amount of padding, a V-shaped depression (notch) may occur at the boundary between the soft bow cross section portion 43 and the outer surface of the die body portion 28. If left unattended, this V-shaped notch can become the starting point of fatigue fracture, which is undesirable. In this regard, the provision of the protruding portion 45b has the advantage of more reliably preventing the occurrence of notches.

[0040] FIG. 2(e) shows a fourth processing step, in which the excess material 45a is cut off from the third intermediate product 46 shown in FIG. 2(c) to obtain the die 20.

[0041] [Mold action] The operation of the above-mentioned mold 10 will be described with reference to FIGS. 4(a) to 4(c). FIG. 4(a) is a diagram showing the state at the start of pressing. 4(a), the metal plate 12 is placed on the punch 60. Then, the punch 60 and the die 20 are moved relatively to each other. Although the punch 60 and the die 20 may be moved together, in this example, the punch 60 is kept stationary and the die 20 is moved toward the punch 60.

[0042] FIG. 4(b) is a diagram showing the shape during pressing. 4(b), the punch top portion 66 of the punch 60 entered the die side wall portion 22 of the die 20. As a result, the plastic working of the metal sheet 12 started.

[0043] FIG. 4(c) shows the shape at the final stage of pressing. 4(c), the punch 60 fully entered the die 20. The metal plate 12 was fully plastically worked. As a result, a formed product 13 having a hat-shaped cross section was obtained.

[0044] 4(b) to 4(c), wear of the die 20 is suppressed due to the presence of the die hardened portion 35. By suppressing wear, the life of the die 20 can be extended.

[0045] 4(c), the die body 28 is softer than the die hardened portion 35. This is because the die body 28 does not require as much wear resistance as the die hardened portion 35. This allows the material cost of the die body 28 to be reduced, and the material cost of the die 20 to be reduced.

[0046] However, if the wear of the die body 28 at the die sidewall 22 is greater than the wear of the die hardened portion 35, the following modification is recommended.

[0047] [First example of mold change] A first modified example of the mold 10 will be described with reference to Figures 5(a) to (c). Figure 5(b) is an enlarged view of part b in Figure 5(a), and Figure 5(c) is a view showing a modified example of the first hardened coating portion 36.

[0048] 5(b), a first hardened coating portion 36 is embedded in the die sidewall portion 22. One end of the first hardened coating portion 36 is connected to the die hardened portion 35.

[0049] [First film cured part] The first hardened coating portion 36 is made of the same material as the die hardened portion 35 described above. The die side wall portion 22 is cut to a predetermined depth, padding is applied to the cut portion, and an excess portion of the padding is cut off, thereby obtaining the first hardened coating portion 36.

[0050] 5(a), the mold 10 is composed of a die 20 and a punch 60, and the die 20 is provided with a first hardened coating portion 36 in addition to a die hardened portion 35. The hardness of the first hardened coating portion 36 is higher than that of the die body portion 28. According to this first modified example, the wear resistance of the die 20 can be further improved.

[0051] The first hardened coating portion 36 may have a cross-sectional shape shown in FIG. 5(c) other than the cross-sectional shape shown in FIG. 5(b). That is, the first hardened coating portion 36 shown in Fig. 5(c) has a tapered shape in which the portion close to the die hardened portion 35 is thin and the further away from the die hardened portion 35 the thicker the portion is, and the thicker portion is embedded in the die main body 28. Because it is embedded in the first hardened coating portion 36, there is an advantage that it is less likely to fall off the die side wall 22 than in Fig. 5(b).

[0052] [Further changes to the first hardened coating] A further modification of the first hardened coating portion 36 is illustrated in FIG. 6(a) and FIG. 6(b), which is a cross-sectional view taken along line bb in FIG. 6(a). As shown in FIG. 6(b), the first hardened coating portion 36 may be a first ridge 37 having an arcuate cross section. That is, as shown in FIG. 6(a), the first hardened coating portion 36 may be a first protrusion 37 extending along the movement axis 61 of the punch.

[0053] Because the first ridges 37 are protrusions, they can be attached later to the molding surface of the die 20. This makes it possible to minimize the range of hardened portions for complex molding surfaces. Since the range is minimized, there is an advantage in that the amount of expensive hard material used can be reduced.

[0054] 4(b) and (c) described above, in the process from Fig. 4(b) to Fig. 4(c), the edge of the metal plate 12 may come into contact with the punch flange portion 64. When it is necessary to impart abrasion resistance to the punch flange portion 64, the second modified example described below is recommended.

[0055] [Second example of mold change] A second modified example of the mold 10 will be described with reference to Figures 7(a) and (b), in which Figure 7(b) is an enlarged view of part b in Figure 7(a).

[0056] As shown in Fig. 7(a), the punch 60 has a second hardened coating portion 67 embedded in the punch flange portion 64. This second hardened coating portion 67 is formed of the same material and in the same manner as the first hardened coating portion (Fig. 5(b), reference numeral 36). Therefore, the second hardened coating portion 67 has a higher hardness than the die body portion 28. The mold 10 is composed of a die 20 and a punch 60. The die 20 has a die hardening portion 35 and a first coating hardening portion 36. The punch 60 has a second coating hardening portion 67.

[0057] 7(b), the second hardened coating portion 67 exhibits wear resistance even when scraped by the edge of the metal plate 12. The second hardened coating portion 67 protects the punch 60.

[0058] [Third example of mold modification] A third modified example of the mold 10 will be described with reference to Figures 8(a) to (c). Figure 8(b) is an enlarged view of part b in Figure 8(a), and Figure 8(c) is a view showing a modified example of the third hardened coating part 74.

[0059] As shown in FIG. 8( b ), the portion where the punch top portion 66 and the punch side wall portion 62 intersect is called a punch shoulder portion 71 , and the portion of the punch 60 excluding the punch shoulder portion 71 is called a punch body portion 72 . The boundary between the punch body 72 and the punch shoulder 71 is a straight line 31 in a cross-sectional view. The outer surface of the punch shoulder 71 is formed as a curved line 32 that is outwardly convex in cross section. One end of the straight line 31 is connected to one end of the curved line 32, and the other end of the straight line 31 is connected to the other end of the curved line 32.

[0060] The punch shoulder 71 is composed of a punch hardened portion 73 having a higher hardness than the punch body 72 . A third hardened coating portion 74 having a hardness higher than that of the punch body 72 is embedded in the punch side wall portion 62 , and one end of this third hardened coating portion 74 is connected to the punch hardened portion 73 .

[0061] The material of the punch body 72 may be the same as the material of the die body 28 described above. The material of the punch hardened portion 73 may be the same as the material of the die hardened portion 35 described above. The material of the third hardened coating portion 74 may be the same as the material of the punch hardened portion 73 .

[0062] As shown in FIG. 8( a ), the mold 10 comprises a die 20 and a punch 60 . The die 20 has a die hardening portion 35 and a first coating hardening portion 36 . The punch 60 has a punch hardened portion 73 and a third coating hardened portion 74 . According to the third modified example, the wear resistance of both the die 20 and the punch 60 is improved.

[0063] As shown in Fig. 8(c), the third hardened coating portion 74 has a tapered shape in which the portion close to the punch hardened portion 73 is thin and the portion away from the punch hardened portion 73 is thicker, and the thicker portion bites into the punch body 72. Because the thicker portion bites into the punch body 72, there is an advantage that the third hardened coating portion 74 is less likely to fall off the punch side wall 62 than in Fig. 8(b).

[0064] 8(b), the punch hardened portion 73 extends in the direction of the drawing. When it is necessary to save hard material, the fourth modified example described below is useful.

[0065] [Fourth example of mold modification] The fourth modified example will be described with reference to FIGS. 9(a) to (e). 9(c) is a view taken along line 9c-9c of FIG. 8, and corresponds to a view seen from the die 20 side.

[0066] As shown in FIG. 9(a), the molded product 13 is a frame member that is generally T-shaped and has a hat-shaped cross section. As shown in FIG. 9(b), the molded product 13 is a frame member that is L-shaped overall and has a hat-shaped cross section.

[0067] FIG. 9(c) shows a punch 60 for plastically working the L-shaped formed product 13 shown in FIG. 9(b). The punch 60 for plastically working the T-shaped formed product 13 shown in FIG. 9(a) is omitted.

[0068] 9(c), punch 60 has a first punch side surface 76 and a second punch side surface 77 intersecting with the first punch side surface 76. Also, a bent portion 78 is formed at the location where the first punch side surface 76 and the second punch side surface 77 intersect. During plastic working, the fluid material gathers from the first punch side surface 76 and the second punch side surface 77 toward the bent portion 78 .

[0069] As shown in FIG. 9( d ), the bent portion 78 is provided with a punch hardened portion 73 and a third hardened coating portion 74 . That is, at the bent portion 78, a large amount of material flows from the punch top portion 66 to the punch shoulder portion 71, and the bent portion 78 is subject to severe wear.

[0070] FIG. 9( e ) is a cross-sectional view of a portion other than the bent portion 78 . As shown in FIG. 9( e ), the punch 60 has no punch hardened portion 73 or third hardened coating portion 74 provided at any portion other than the bent portion 78 . According to the fourth modified example, the partial bent portion 78 is made of a hard material, so that the cost of the punch 60 can be reduced.

[0071] [Example of change to the third hardened coating] A modification of the third hardened coating portion 74 is illustrated in FIG. 10(a) and FIG. 10(b), which is a cross-sectional view taken along line bb in FIG. 10(a). As shown in FIG. 10(b), the third hardened coating portion 74 may be a second protrusion 79 having an arcuate cross section. That is, as shown in FIG. 10(a), the third hardened coating portion 74 may be a second protrusion 79 extending along the movement axis 61 of the punch.

[0072] Because the second ridges 79 are protrusions, they can be attached later to the forming surface of the punch 60. This makes it possible to minimize the range of the hardened portion for a complex forming surface. Since it is minimized, there is an advantage that the amount of expensive hard material used can be reduced.

[0073] [Fifth example of mold modification] As there is a demand for lower costs for the mold 10, the fifth modified example provides a structure that can meet this demand. A fifth modified example of the mold 10 will be described with reference to Figures 11(a) and (b), in which Figure 11(b) is an enlarged view of part b in Figure 11(a).

[0074] As shown in FIG. 11( a ), the mold 10 comprises a die 20 and a punch 60 . The die 20 has a die recess 47 into which a punch 60 enters and a die flange portion 24 extending in a direction intersecting a movement axis 61 of the punch. The punch 60 has a punch flange portion 64 facing the die flange portion 24. In this punch flange portion 64, a second hardened coating portion 67 having a higher hardness than the punch flange portion 64 is embedded.

[0075] The second hardened coating portion 67 has a hardness higher than that of the punch flange portion 64 . 11(b), the second hardened coating portion 67 exhibits wear resistance even when scraped by the edge of the metal plate 12. The second hardened coating portion 67 protects the punch flange portion 64.

[0076] In the invention according to the fifth modification, the punch flange portion 64, which is only a small part of the die 10, is made the hardened portion, so the volume of the hardened portion is very small. Because the volume of the hardened portion is very small, the cost of forming the hardened portion is very small. The reduced cost of forming the hardened portion reduces the manufacturing cost of the die 10. That is, the present invention provides a technique that can reduce the manufacturing costs of the mold 10.

[0077] [Example of the sixth change in mold] A sixth modification of the mold 10 will be described with reference to FIG. 12, the mold 10 includes the die 20, the punch 60, a blank holder 81, and a pad 82. That is, the mold 10 further includes the blank holder 81 that presses the metal sheet 12 against the die flange portion 24. The pad 82 serves to press the metal sheet 12 relatively against the punch 60.

[0078] The die 20 comprises a die body 28 and a die shoulder 27. The die shoulder 27 is a die hardened portion 35. The die hardened portion 35 enhances the wear resistance of the die 20. A holder hardened portion 83 having a harderness than the die main body 28 is embedded in a portion of the blank holder 81 facing the die flange portion 24. The holder hardened portion 83 enhances the wear resistance of the blank holder 81.

[0079] [Seventh example of mold modification] A seventh modification of the mold 10 will be described with reference to FIG. As shown in FIG. 13, the mold 10 comprises a die 20, a punch 60, a blank holder 81 and a pad 82. The die flange portion 24 and the blank holder 81 are further provided with a draw bead 85 for controlling the inflow of the metal sheet 12 . The draw bead 85 is composed of a bead hardened portion 86 that has a higher hardness than the die body portion 28 .

[0080] The drawbead 85 consists of a recess 87 and a protrusion 88 . One of the recess 87 and the protrusion 88 is provided on the die flange portion 24, and the other is provided on the blank holder 81. Preferably, the recess 87 is provided on the blank holder 81, and the protrusion 88 is provided on the die flange portion 24.

[0081] The drawbead 85 strongly presses and pulls the metal plate 12, so the inflow of material is large. The greater the inflow of material, the more severe the wear. Therefore, the drawbead 85 is required to have higher wear resistance than other parts. The draw bead 85 is configured with a bead hardened portion 86 having high hardness, and therefore has high wear resistance.

[0082] By the way, the specification or setting of the cutting plane 44a described in Fig. 2(b) is important. This specification or setting can be performed by utilizing a wireframe by CAD (computer-aided design). The wireframe will be described below in order.

[0083] 14(a) to (h) are diagrams illustrating a manufacturing method of a mold 10 using a wire frame and a ruled surface.

[0084] FIG. 14(a) is a diagram similar to FIG. 1(b), but in order to facilitate the following explanation, the reference numerals in FIG. 1(b) have been changed and FIG. 1(b) has been turned upside down. 14(a), the die body 28 has a flat first surface 91 and a second surface 92 different from the first surface 91. The second surface 92 is also flat.

[0085] Wireframe The wire frame will be explained based on FIGS. 14(b) to (f), and the ruled surface corresponding to the cut surface will be explained based on (g) and (h). A ruled surface is a CAD term, written as "ruled surface" in English, and refers to a surface surrounded by a specific group of edges (the definition of edges will be described later). Since edges appear on the surface, a ruled surface is the same as a ruled surface.

[0086] 14(b) shows a vertex 93. This vertex 93 is a point set on the CAD screen. 14(c) shows a straight edge 94. This edge 94 is a line in which two vertices 93 are connected by a straight line. 14(d) shows a curved edge 95. This edge 95 is a line in which two vertices 93 are connected by a curve. The curve is defined by a radius of curvature R.

[0087] 14(e) shows a wire 96. The wire 96 is a bent line or a meandering line in which straight edge lines 94 are connected in series, or curved edge lines 95 are connected in series, or a straight edge line 94 and a curved edge line 95 are connected in series. 14(f) shows a wire frame 97. The wire frame 97 is a skeleton structure in which a plurality of wires 96 are arranged in a lattice pattern.

[0088] [Rule surface] In FIG. 14(e), the vertical edge 94 is replaced with a linear edge 94v passing through the first surface, and the horizontal edge 94 is replaced with a linear edge 94h passing through the second surface. Then, a vertex 93 existing at the joint between a straight edge line 94v passing through the first face and a curved edge line 95 connected to this straight edge line 94v is defined as a first inflection point 98. Similarly, a vertex 93 existing at the joint between a straight edge 94h passing through the second face and a curved edge 95 connected to this straight edge 94h is defined as a second inflection point 99.

[0089] Next, as shown in Fig. 14(g), the first inflection point 98 and the second inflection point 99 are connected by a line 101. This line 101 corresponds to the straight line 31 shown in Fig. 1(b) and also corresponds to the cross section 44a shown in Fig. 2(b). When the two-dimensional representation of FIG. 14(g) is converted into a three-dimensional representation, it becomes FIG. 14(h).

[0090] 14(h), a surface surrounded by a line 101 connecting the first inflection point 98 and the second inflection point 99, wires 96, 96 perpendicular to this line 101 (including substantially perpendicular to this line 101), and a line 102 at the back forms a ruled surface 103. This ruled surface 103 corresponds to the cut surface 44a.

[0091] As described above, the press die is shown by a wire frame 97 created by CAD, and a straight line (FIG. 1(b), reference numeral 31) is determined by a line 101 connecting a first inflection point 98 and a second inflection point 99. As a result, the cutting surface (FIG. 2(b), reference numeral 44a) is uniquely determined, leaving no room for personal differences or human error.

[0092] [Method of manufacturing molds using wire frames] The method of manufacturing a mold using a wire frame can be summarized as follows. 14(a), the die body 28 has a flat first surface 91 and a flat second surface 92 different from the first surface 91. The die shoulder 27 is provided between the first surface 91 and the second surface 92, and is formed with a curved ridge 95 on the outer surface.

[0093] As shown in Figures 14(b) to (h), a die is represented by a wire frame 97, which is defined by a vertex 93 which is a point on the screen, edges 94, 95 which connect the two vertices 93 by a straight line or a curve, a wire 96 which connects the multiple edges 94, 95 in series, and a skeletal structure composed of the multiple wires 96.

[0094] Then, a vertex 93 located at the joint between a straight edge 94v passing through the first face 91 and a curved edge 95 connected to this straight edge 94v is defined as a first inflection point 98, a vertex located at the joint between a straight edge 94h passing through the second face 92 and a curved edge 95 connected to this straight edge 94h is defined as a second inflection point 99, and a ruled surface 103 is defined by a line 101 connecting the first inflection point 98 and the second inflection point 99.

[0095] Following the above definitions, the mold manufacturing method shown in Figures 2(a)-(e) is carried out. That is, a first processing step of obtaining a first intermediate product 42 processed into a shape following the die; a second processing step of cutting out a soft bow cross-section portion 43 having the same shape as the die shoulder portion 27 from the first intermediate product 42 along the cut surface 44a to obtain a second intermediate product 44 including the cut surface 44a; a third processing step of padding the cut surface 44a of the second intermediate product 44 with a material having a higher hardness than the die body 28 to obtain a third intermediate product 46 including a padded portion 45 having a cross-sectional shape obtained by adding an excess pad 45a to the soft bow cross-sectional portion 43; and a fourth processing step of obtaining a die by cutting off excess pad 45a from the third intermediate product 46.

[0096] According to this die manufacturing method, the die shoulder and die body can be easily set by forming a wire frame on a CAD screen and setting a ruled surface. Since it is easy to set, the design cost can be reduced. The reduced design cost reduces the manufacturing cost of the die. That is, the present invention provides a technique that can reduce the manufacturing costs of the mold 10.

[0097] Preferably, the padding in the third processing step includes a protruding portion protruding to the first surface and the second surface. The protruding portion is the same as the protruding portion 45b shown in FIG.

[0098] A mold 10 shown in Fig. 1 is prepared, and a molded product 13 having a hat-shaped cross section is obtained through the steps shown in Fig. 4(a) to (c). When the steps shown in Fig. 4(a) to (c) are repeated, the die hardened portion 35 shown in Fig. 4(a) gradually wears or chips. When this wear or chipping exceeds an allowable value, the mold 10 is repaired or replaced with a new mold 10. 4(a) to 4(c) are repeated, it takes time to inspect the mold 10 as a whole and find out whether there is an abnormality in the mold 10. Therefore, a mold inspection method that can replace the overall inspection is required.

[0099] [Partial type] 15(a), the die 20 is preferably composed of a main mold 38 and a partial mold 39 that is removably attached to the main mold 38. The partial mold 39 is provided with a die hardening portion 35.

[0100] Plastic working is applied to the metal plate 12 by a mold (FIG. 1(a), reference numeral 10) including such a die 20. After multiple plastic workings, the bolts B are loosened and the partial mold 39 is removed from the main mold . FIG. 15(b) shows the removed mold part 39.

[0101] Incidentally, the punch 60 may also be composed of a main die 38 and a partial die 39 .

[0102] [Mold inspection equipment] A mold inspection apparatus for carrying out the mold inspection method is shown in FIG. 15(c). As shown in Figure 15 (c), the mold inspection device 110 comprises, for example, a stand 111 on which the partial mold 39 is placed, a robot 113 that moves a non-contact surface roughness meter 112 in three dimensions, a discrimination unit 114 that obtains roughness information from the surface roughness meter 112 and discriminates whether the roughness is within an allowable value, and an alarm 115 that emits sound or light when the roughness exceeds the allowable value.

[0103] [Surface roughness gauge] The non-contact surface roughness meter 112 is a type of distance meter that emits a beam of light such as laser light or infrared light, receives the reflected light, and measures the time it takes for the light to return. The distance from the surface roughness meter 112 to the partial mold 39 is calculated based on the speed of light and the time. The distance changes when either or both of the partial mold 39 and the surface roughness meter 112 are moved. This change in distance represents the roughness.

[0104] When a scratch occurs on the surface of the part mold 39, there is a large change in the distance measured by the surface roughness meter 112. In other words, the surface roughness meter 112 can detect the depth of the scratch. The allowable value (threshold value) of the depth of the scratch is determined with reference to the surface roughness of the normal part mold 39 . When the measured value exceeds a threshold value, the discriminator 114 discriminates that an abnormality has occurred. When the alarm 115 receives abnormality information from the discrimination unit 114, it issues an alarm using sound, flashing light, or the like.

[0105] [Mold inspection method] That is, the present invention provides a mold inspection method as described below. As shown in FIG. 15(a), the die 20 is composed of a main mold 38 and a partial mold 39 removably attached to the main mold 38, and the partial mold 39 is provided with a die hardening portion 35. After the metal plate is subjected to plastic working by a metal mold including the die 20, the partial mold 39 is removed from the main mold 38. As shown in FIG. 15( c ), an inspection step of detecting the depth of scratches occurring on the surface of the part mold 39 by a surface roughness meter 112 ; a discrimination step in which the discrimination unit 114 discriminates that the partial mold 39 is sound if the depth of the detected flaw is within a threshold value, and that the partial mold 39 is unsound if the depth of the detected flaw exceeds the threshold value; and an alarm step of issuing an alarm by an alarm device 115 when the mold part 39 is unsound.

[0106] When inspecting the die 20 for abnormalities such as wear, it is not desirable to inspect the entire die 20, but this increases the inspection time. In this regard, the mold inspection method of the present invention has the advantage that only the partial mold 39 is inspected, and therefore the inspection time is shortened.

[0107] In addition, when inspecting the entire die 20, if the die hardening portion 35 is formed in the back or in a corner of the die 20, inspection of the die hardening portion 35 becomes difficult. In this regard, according to the mold inspection method of the present invention, since the removed mold part 39 is inspected, there is an advantage that the inspection of the die hardening portion 35 becomes easy.

[0108] The above-mentioned inspection method is suitable for inspecting the die 20, but can also be applied to the punch 60. That is, the punch 60 is composed of a main mold 38 and a partial mold 39 removably attached to the main mold 38, and the partial mold 39 is provided with a punch hardened portion 73. a step of removing the partial die 39 from the main die 38 after the metal plate has been plastically worked by a die including the punch 60; an inspection step of detecting the depth of scratches on the surface of the part mold 39 by a surface roughness meter 112; a discrimination step in which the discrimination unit 114 discriminates that the partial mold 39 is sound if the depth of the detected flaw is within a threshold value, and that the partial mold 39 is unsound if the depth of the detected flaw exceeds the threshold value; and an alarm step of issuing an alarm by an alarm device 115 when the mold part 39 is unsound.

[0109] [Example of change to die hardening part] 16, when the maximum distance T between the curved line 32 and the straight line 31 in the die shoulder 27 is less than 1 mm, an arc groove 117 (or a square groove) is drilled in the die body 28. Then, the die hardened portion 35 is made to protrude into the arc groove 117 (or the square groove).

[0110] Alternatively, when the angle θ between the punch movement axis 61 and the straight line 31 in the die shoulder portion 27 is less than 45°, an arc groove 117 (or a square groove) is drilled in the die body portion 28. Then, the die hardened portion 35 is caused to protrude into the arc groove 117 (or the square groove).

[0111] The protruding protrusion 118 exerts an anchoring effect, which makes it difficult for the die shoulder 27 to come off from the die body 28. The structure shown in FIG. 16 may be applied to the punch shoulder portion (FIG. 8(b), reference numeral 71).

[0112] [Further modification examples of the die hardening section] The die curing portion 35 shown in FIG. 1(b) extends in the front-to-back direction of the drawing. However, as shown in Fig. 17, the die hardening portion 35 may be dome-shaped. The dome-shaped die hardening portions 35 may be interspersed on the same line.

[0113] Since the die hardening portion 35 may have either a linear shape or a dome shape, the degree of freedom in designing the die hardening portion 35 is increased. The structure shown in FIG. 17 may be applied to the punch shoulder portion (FIG. 8(b), reference numeral 71).

[0114] [Further modification examples of the die hardening section] 18, the die shoulder 27 may be a two-humped camel-shaped die hardening portion 35 having another curved line 32B adjacent to the curved line 32. This allows greater freedom in designing the die hardening portion 35. The structure shown in FIG. 18 may be applied to the punch shoulder portion (FIG. 8(b), reference numeral 71). [Industrial Applicability]

[0115] The present invention is suitable for a mold including a die comprising a die body and a die shoulder. [Explanation of symbols]

[0116] 10... die, 12... metal plate, 13... molded product, 20... die, 22... die side wall portion, 24... die flange portion, 25... back, 26... die top portion, 27... die shoulder portion, 28... die main body portion, 31... straight line, 32... curved line, 32B... curved line, 33, 98... first inflection point, 34, 99... second inflection point, 35... die hardened portion, 36... first coating hardened portion, 37... first protrusion, 38... main mold, 39... partial mold, 41... die blank, 42... first intermediate product, 43... soft bow cross section portion, 44... second intermediate product, 44a... cutting surface, 45... padding portion, 45a... excess padding, 45b... overhanging portion, 46... third intermediate product, 47... die recess, 60... punch, 6 1...moving axis, 62...punch side wall portion, 64...punch flange portion, 66...punch top portion, 67...second coating hardened portion, 71...punch shoulder portion, 72...punch main body portion, 73...punch hardened portion, 74...third coating hardened portion, 76...first punch side surface, 77...second punch side surface, 78...bent portion, 79...second protrusion, 81...blank holder, 83...holder hardened portion, 85...draw bead, 86...bead hardened portion, 91...first surface, 92...second surface, 93...vertex, 94...straight ridge, 95...curved ridge, 96...wire, 97...wire frame, 112...surface roughness meter, 114...discrimination portion, 115...alarm.

Claims

1. A die comprising a die and a punch for plastically working a metal plate into a hat-shaped cross section, the die includes a die side wall portion extending along a movement axis of the punch, a die flange portion extending from the die side wall portion in a direction intersecting the movement axis of the punch, and a die top portion located at the back of the die side wall portion, the punch includes a punch side wall portion facing the die side wall portion, a punch flange portion facing the die flange portion, and a punch top portion facing the die top portion, The portion where the die flange portion and the die side wall portion intersect is called a die shoulder portion, and the portion of the die excluding the die shoulder portion is called a die main body portion. In a cross-sectional view, the boundary between the die body and the die shoulder is a straight line, the outer surface of the die shoulder is a curved line that is convex outward, one end of the straight line is connected to one end of the curved line, and the other end of the straight line is connected to the other end of the curved line, the die shoulder portion is formed of a die hardened portion having a harderness than the die body portion, A mold in which a first hardened coating portion having a hardness higher than that of the die main body portion is embedded in the die side wall portion, and one end of the first hardened coating portion is connected to the die hardened portion.

2. The mold according to claim 1, The die, wherein the first hardened coating portion is a first protrusion extending along the movement axis of the punch.

3. The mold according to claim 1, The first coating hardened portion has a tapered shape that is thin near the die hardened portion and thickens as it moves away from the die hardened portion, and the thicker portion bites into the die main body.

4. The mold according to claim 1 or 2, The punch is a die in which a second hardened coating portion having a hardness higher than that of the die body portion is embedded in the punch flange portion.

5. The mold according to any one of claims 1 to 3, The portion where the punch top portion and the punch side wall portion intersect is called a punch shoulder portion, and the portion of the punch excluding the punch shoulder portion is called a punch main body portion. a boundary between the punch body and the punch shoulder is a straight line in a cross-sectional view, an outer surface of the punch shoulder is a curved line that is convex outward in a cross-sectional view, one end of the straight line is connected to one end of the curved line, and the other end of the straight line is connected to the other end of the curved line, the punch shoulder portion is constituted by a punch hardened portion having a harderness than the punch body portion, A die in which a third hardened coating portion having a hardness higher than that of the punch body portion is embedded in the punch side wall portion, and one end of this third hardened coating portion is connected to the punch hardened portion.

6. The mold according to claim 5, The punch forms the metal plate into a formed product having a T-shape or L-shape and a hat-shaped cross section, When viewed from the die, the punch has a first punch side surface and a second punch side surface intersecting the first punch side surface, and has a bent portion at a portion where the first punch side surface and the second punch side surface intersect, A die, wherein the punch hardened portion and the third hardened coating portion are provided only in the bent portion.

7. The mold according to claim 5, The third coating hardened portion has a tapered shape that is thin near the punch hardened portion and thickens as it moves away from the punch hardened portion, and the thicker portion bites into the punch body.

8. The mold according to claim 5, The third hardened coating portion is a second protrusion extending along the movement axis of the punch.

9. A die for performing plastic working on a metal plate, comprising a die and a punch, The die includes a die recess into which the punch enters and a die flange extending in a direction intersecting a movement axis of the punch, The punch includes a punch flange portion facing the die flange portion, A second hardened coating portion having a harderness than the punch flange portion is embedded in the punch flange portion.

10. The mold according to claim 1, The die further includes a blank holder that presses the metal plate against the die flange portion, The die has a holder hardened portion, the hardened portion having a harderness than that of the die body portion, embedded in a portion of the blank holder facing the die flange portion.

11. The mold according to claim 10, The die flange portion and the flank holder further include a draw bead for controlling the inflow of the metal plate, The draw bead is composed of a bead hardened portion having a higher hardness than the die body portion.

12. A method for manufacturing the mold according to claim 1, comprising the steps of: the die body has a first flat surface and a second flat surface different from the first surface; the die shoulder is between the first surface and the second surface, and has an outer surface formed with a curved ridge; The die is shown by a wire frame, and the wire frame is defined by vertices that are points on a screen, edges that connect two of the vertices with straight lines or curved lines, wires that connect a plurality of the edges in series, and a skeleton structure that is composed of a plurality of the wires, A vertex at a joint between a straight edge line passing through the first surface and the 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 the curved edge line connected to the straight edge line is defined as a second inflection point, and when a cut surface is defined by a straight line connecting the first inflection point and the second inflection point, A first processing step of obtaining a first intermediate product processed into a shape following the die; A second processing step of obtaining a second intermediate product including the cut surface by cutting off a soft bow cross-section portion having the same shape as the die shoulder from the first intermediate product along the cut surface; a third processing step of padding the cut surface of the second intermediate product with a material having a higher hardness than the die body to obtain a third intermediate product including a padded portion having a cross-sectional shape in which excess material is added to the soft bow cross-sectional portion; and a fourth processing step of obtaining the die by cutting off the excess material from the third intermediate product.

13. The mold manufacturing method according to claim 12, The mold manufacturing method, wherein the build-up portion in the third processing step includes a protruding portion that protrudes toward the first surface and the second surface.

14. The die according to claim 1 comprises a main mold and a partial mold removably attached to the main mold, and the partial mold is provided with the die hardening portion, a step of removing the sub mold from the main mold after the metal plate has been plastically worked by a metal mold including the die; an inspection step of detecting the depth of scratches occurring on the surface of the part mold by a surface roughness meter; a discrimination step in which a discrimination unit discriminates that the partial mold is sound if the depth of the detected flaw is within a threshold value, and that the partial mold is unsound if the depth of the detected flaw exceeds the threshold value; and an alarm step of issuing an alarm when the mold part is unsound.

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