Damage evaluation device and damage evaluation method for press forming die

Abstract

The damage evaluation device for a press forming die according to the present application is provided with: an evaluation die provided in a press machine that performs press forming of a metal material; and an observation device that observes damage behavior of a die steel material and a surface coating film that constitute the evaluation die, the evaluation die being provided with: a hole forming unit that forms a hole portion in the metal material; a first shearing unit that shears the metal material in which the hole portion is formed into an arbitrary metal member shape; and a second shearing unit that cuts off the metal member from the metal material, the dies of the hole forming unit, the first shearing unit, and the second shearing unit being formed of the die steel material and having a configuration that enables replacement with another die having an arbitrary material and in which an arbitrary surface coating film treatment is implemented.

Description

TECHNICAL FIELD

[0001] The present application relates to a damage evaluation device for a press forming die and a damage evaluation method. BACKGROUND

[0002] In recent years, from the viewpoint of vehicle body weight reduction and collision safety improvement, the application of high-tension steel sheets having high strength is being promoted in vehicle body frame members. Generally, vehicle body frame members are mass-produced by press forming using a die. However, high-tension steel sheets lack ductility and have high strength, and thus cracks, wrinkles, springback (poor dimensional accuracy) are significantly generated by press forming. Therefore, countermeasures against such forming defects are required. In addition, in press forming of high-tension steel sheets, not only the above-mentioned forming defects, but also die damage is a major problem.

[0003] Generally, if the strength of a material increases, the load required for shearing processing that cuts the material increases, and in press forming using a die, the contact surface pressure of the die becomes high. Therefore, defects such as damage, wear, and sintering of the die steel material are easily generated. In addition, if press forming is continued in a state where the die is damaged, not only the surface appearance of the press formed product is damaged, but also the quality of the sheared surface decreases, and it can greatly affect the formability in the next press forming process, hydrogen embrittlement resistance after becoming a product, and the like. Against this background, countermeasures against die damage such as damage, wear, and sintering of the die steel material and the surface coating film have been proposed.

[0004] Specifically, in Patent Literature 1, a method is described in which, in order to prevent sintering at the time of press forming, a coating film treatment based on the PVD (Physical Vapor Deposition) method is applied to the forming surface that contacts the steel sheet. In addition, in Patent Literatures 2 and 3, a die steel material in which die damage is less likely to occur is described by optimizing the composition. In addition, in Patent Literature 4, a method is described in which a strip-shaped steel sheet is sandwiched with opposing block-shaped steel materials, the steel sheet is directly pulled out, and then the surface of the block-shaped steel material and the like are observed, thereby evaluating the die adhesion. In addition, in Patent Literature 5, an evaluation die for evaluating die adhesion by press forming using a die is described, the die having a punch having three or more recesses in the outer periphery when viewed in parallel with the press direction, and a die having a fitting portion into which the punch that has relatively moved in the press direction is fitted with a prescribed gap.

[0005] Patent Literature 1: Japanese Patent No. 5135479

[0006] Patent Literature 2: Japanese Patent Application Laid-Open No. 2011-189419

[0007] Patent Literature 3: Japanese Patent No. 4737606

[0008] Patent Document 4: Japanese Patent No. 4677804

[0009] Patent Document 5: Japanese Patent Application Laid-Open No. 2010-167437

[0010] As described in Patent Documents 1 to 3, as a countermeasure against die damage, a die steel material, a coating treatment that is excellent in durability is effective. However, recently, die steel materials, coating treatments are provided from various manufacturers, and it is difficult to select which die steel material, coating treatment is effective. On the other hand, the limit of the number of times of sliding test, press forming test performed by the method described in Patent Documents 4, 5 is several tens to several hundreds of times or so. Therefore, evaluation of die damage due to press forming performed several thousands to several ten thousands of times in actual mass production press forming is not sufficient, and it is difficult to quantitatively evaluate die life such as how many times of press forming will cause die damage. SUMMARY

[0011] The present application was accomplished in view of the above-described problems, and aims to provide a die damage evaluation device and a die damage evaluation method that can quantitatively evaluate die damage for any die steel material and coating treatment.

[0012] The die damage evaluation device of the present application is provided with: an evaluation die provided in a press machine that performs press forming of a metal material; and an observation device that observes damage behavior of a die steel material and a surface coating that constitute the evaluation die, the evaluation die being provided with: a piercing unit that forms a hole portion in the metal material; a first shearing unit that shears the metal material in which the hole portion is formed into an arbitrary metal member shape; and a second shearing unit that cuts off the metal member from the metal material, the dies of the piercing unit, the first shearing unit, and the second shearing unit being formed of a die steel material, and having a configuration that can be replaced with another die having an arbitrary material and in which an arbitrary surface coating treatment is performed.

[0013] It can also be that the evaluation die is provided with: a press forming unit that press forms the metal material after sheared by the first shearing unit into a hat-shaped cross-sectional shape having a ceiling face, a vertical wall portion continuous with the ceiling face, and a flange portion continuous with the vertical wall portion; and a third shearing unit that shears a part of the flange portion, the dies of the press forming unit and the third shearing unit being formed of a die steel material, and having a configuration that can be replaced with another die having an arbitrary material and in which an arbitrary surface coating treatment is performed, the second shearing unit cutting off the metal member of the hat-shaped cross-sectional shape from the metal material after sheared by the third shearing unit.

[0014] The hat-shaped cross-sectional shape can have a convex shape on one of the longitudinal wall portions.

[0015] The damage evaluation method of the press forming die according to the present application includes a step of observing damage behavior of a die steel material and a surface coating film constituting an evaluation die after press forming of a metal material has been repeated an arbitrary number of times using the evaluation die provided in a press machine, the evaluation die including a piercing unit that forms a hole portion in the metal material, a first shearing unit that shears the metal material in which the hole portion is formed into an arbitrary metal member shape, and a second shearing unit that cuts the metal member from the metal material, the die of the piercing unit, the first shearing unit, and the second shearing unit being formed of the die steel material and having a configuration capable of being replaced with another die having an arbitrary material and subjected to an arbitrary surface coating film treatment.

[0016] The evaluation die can include a press forming unit that press forms the metal material sheared by the first shearing unit into a hat-shaped cross-sectional shape having a top plate surface, a longitudinal wall portion continuous with the top plate surface, and a flange portion continuous with the longitudinal wall portion, and a third shearing unit that shears a portion of the flange portion, the die of the press forming unit and the third shearing unit being formed of the die steel material and having a configuration capable of being replaced with another die having an arbitrary material and subjected to an arbitrary surface coating film treatment, the second shearing unit cutting the metal member of the hat-shaped cross-sectional shape from the metal material sheared by the third shearing unit.

[0017] The hat-shaped cross-sectional shape can have a convex shape on one of the longitudinal wall portions.

[0018] According to the damage evaluation device and the damage evaluation method of the press forming die according to the present application, the die damage can be quantitatively evaluated for an arbitrary die steel material and coating film treatment. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a schematic view showing the overall configuration of a damage evaluation device of a press forming die according to an embodiment of the present application.

[0020] Figure 2 is a view showing the configuration of a hat-shaped cross-sectional member.

[0021] Figure 3 is a schematic view showing a configuration example of an evaluation die.

[0022] Figure 4 is a view showing the shape of a coil material subjected to press forming by the evaluation die shown in Figure 3

[0023] Figure 5 ​This is a diagram used to illustrate the flange trimming process.

[0024] Figure 6 This is a diagram used to illustrate the flange trimming process.

[0025] Figure 7 This diagram illustrates the partition trimming process. Detailed Implementation

[0026] Hereinafter, with reference to the accompanying drawings, a damage evaluation device and a damage evaluation method for a stamping die, as an embodiment of the present invention, will be described.

[0027] [Overall Structure]

[0028] First, refer to Figure 1 The overall structure of the damage evaluation device for stamping molds, which is one embodiment of the present invention, will be described.

[0029] Figure 1 This is a schematic diagram showing the overall structure of a damage evaluation device for a stamping die, as one embodiment of the present invention. Figure 1 As shown, the damage evaluation device 1 for stamping dies according to one embodiment of the present invention includes a pay-off reel 2, an uncoiler leveler 3, a stamping device 4, a conveying device 5, a waste bag 6, and an observation device 100. In the damage evaluation device 1 for stamping dies according to one embodiment of the present invention, a spiral-shaped metal material (hereinafter referred to as coil) S (mainly high-tensile steel plate) to be stamped is placed on the pay-off reel 2. First, the unwound coil S is supplied to the uncoiler leveler 3. Next, the coil S, whose winding marks have been removed by the uncoiler leveler 3, is conveyed into the evaluation die 10 installed in the stamping device 4. Next, after the coil S is stamped using the evaluation die 10, the coil S is conveyed in the forward feed direction at a predetermined interval, and the same stamping process is repeated. Next, although the roll S conveyed to the inside of the evaluation mold 10 is connected, it is cut off in parts during the final process of the evaluation mold 10. After being moved out of the stamping device 4 by the conveying device 5, it is conveyed to the waste bag 6, etc. Then, the damage behavior of the mold steel constituting the evaluation mold 10 and the surface coating is observed using the observation device 100.

[0030] [Evaluation of mold]

[0031] Next, refer to Figures 2-7 The structure of the evaluation mold 10 will be explained. Furthermore, in the following description, continuous stamping will be used. Figure 2 The evaluation mold for the cap-shaped cross-section component 30 shown in (a) to (c) will be used as an example for explanation. Figure 2As shown in (a) to (c), the hat-shaped cross-section member 30 includes: a top plate surface 30a; a longitudinal wall portion 30b and a flange portion 30c continuously formed relative to the top plate surface 30a; and a joggle shape 30d given to one of the longitudinal wall portions 30b. When stamping this hat-shaped cross-section member 30, the coil material S is generally made of high-tensile steel sheet with a tensile strength of 980 MPa or higher that significantly causes die damage, but any material can also be used. Furthermore, for example, if the top plate surface width is 50 mm, the longitudinal wall height is 50 mm, and the flange length is approximately 30 mm, then the width of the coil material S is approximately 200 mm, depending on the size of the part to be stamped. Additionally, the surface of the coil material S can be either a non-plated material or a plated material. In the case of a non-plated material, it is possible to evaluate the die damage caused by the material sintering into the die during stamping. On the other hand, when the coating material is used, it is possible to use molten galvanized steel sheet, alloyed molten galvanized steel sheet, electro-galvanized steel sheet, etc. in the evaluation, and to evaluate the coating adhesion behavior to the mold according to each coating type.

[0032] Figure 3 (a) to (f) are schematic diagrams showing examples of the configuration of the evaluation mold 10. Figure 4 It means being Figure 3 The diagram shows the shape of the coil S formed by the evaluation die 10. (See diagram for example.) Figure 3 As shown in (a) to (f), the evaluation mold 10 is composed of molds for performing six stamping and forming processes. Starting from the forward feeding direction of the coil S, it has molds for the first punching process, the blanking process, the second punching process, the bending process, the flange trimming process, and the partition trimming process. All molds are arranged in a straight line and concentrated in the evaluation mold 10. Each mold has upper blades such as a punching punch 11, a blanking upper blade 12, a bending blade 13, and a trimming upper blade 14, a button die 15, a blanking lower blade 16, a punch 17, a trimming lower blade 18, and a pressure plate 19.

[0033] Furthermore, since no significant force is applied to the pressure plate 19 during stamping, the pressure plate 19 can also be made of ordinary carbon steel such as S45C. Additionally, in Figure 3The platen 19 of each mold in (a) to (f) is shown separated, but the platen 19 of each mold can also be made as a unitary body joined within the evaluation mold 10. In addition, the upper punch and the lower punch are subjected to a large force in the press molding, and become the evaluation object of the occurrence of mold damage, so the respective mold steels are made in a replaceable configuration, and can be fixed to the evaluation mold 10 main body made of a casting or the like with a bolt or the like. These mold steels can be, for example, SKD11, a cold work die steel, SKH51, a high speed steel, or the like, which can be arbitrarily replaced according to the evaluation purpose. In addition, regarding the coating treatment of the mold steel, the mold damage behavior can also be evaluated without coating treatment or with arbitrary coating treatment such as PVD coating of the respective mold steels.

[0034] Further, as the replaceable configuration of the mold steel, a configuration in which the shear gap of the shear unit of the mold is always the same can be exemplified, which is replaced by a positioning member such as a positioning pin. In addition, the material and the surface coating of the mold in each press molding process do not necessarily need to be the same. In addition, if the mold is a left-right symmetrical shape, in order to improve the evaluation efficiency, the material and the surface coating of the left and right molds can also be different.

[0035] Hereinafter, each press molding process will be described.

[0036] (First and second piercing processes)

[0037] As shown in (a) and (c) of Figure 3 , in the first and second piercing processes, a piercing punch 11 is used to perform piercing processing of forming a hole portion 20 (refer to Figure 4 ) in the coil material S. However, the hole portion 20 formed by the mold shown in (a) of Figure 3 is formed for the purpose of inserting a guide pin for positioning the coil material S in the subsequent process, but the formation of the hole portion 20 by the mold shown in (c) of Figure 3 is arbitrary.

[0038] (Punching process)

[0039] As shown in (b) of Figure 3 , in the punching process, a punching upper punch 12 and a punching lower punch 16 are used to shear the outer peripheral portion 21 (refer to Figure 4 ) of the hat-shaped cross-sectional member 30 from the coil material S into a "コ" shape. The length and the shape of the sheared coil material S can be determined according to the shape of the hat-shaped cross-sectional member 30 to be press molded. In addition, the corner portion sheared into a "コ" shape can be a right angle, or can have an R shape.

[0040] (Bending process)

[0041] As shown in (a) of Figure 3As shown in (d), in the bending process, a bending cutter 13 is used to press the coil S into a cap-shaped cross-section having a top surface 30a, a longitudinal wall portion 30b continuous with the top surface 30a, and a flange portion 30c. Specifically, after the top surface portion of the coil S is held by the pressure plate 19, the longitudinal wall portion 30b and the flange portion 30c are pressed and formed using the bending cutter 13. Furthermore, the cap-shaped cross-section can be arbitrarily determined. For example, the angle between the top surface 30a and the longitudinal wall portion 30b is usually around 90 to 150 degrees; the closer to 90 degrees, the easier it is to cause die damage. Alternatively, a cam mechanism or the like can be used to bend at a bending angle of less than 90 degrees.

[0042] In this embodiment, the longitudinal wall portion 30b is given a back-cut shape 30d (see reference). Figure 2 , Figure 4 By bending and forming the back-cut shape, very high contact surface pressure is generated on the bending die 13, which easily leads to die damage. Figure 2 As shown in (a) to (c), by providing a back-cut shape 30d only in one longitudinal wall portion 30b, the difference in mold damage generation behavior caused by the presence or absence of the back-cut shape can be evaluated through a single stamping process. Furthermore, the back-cut shape 30d can be any shape, including triangular and rectangular shapes. The closer the back-cut shape 30d is to a rectangular shape, the more prone it is to mold damage. Additionally, the protrusion height of the back-cut shape 30d can be arbitrarily set. The higher the protrusion height, the more prone it is to mold damage.

[0043] (Flange finishing process)

[0044] like Figure 3 As shown in (e), in the flange trimming process, a portion of the flange portion 30c of the cap-shaped cross-section component 30, which is formed by stamping during the bending process, is sheared using the trimming upper cutter 14. Specifically, after the cap-shaped cross-section component 30 is held by a pressure plate 19 of the same shape as the cap-shaped cross-section component 30, the flange portion 30c exposed from the pressure plate 19 is sheared using the trimming upper cutter 14. Figure 5 As shown in (a), the trimming blade 14 can cut in the width direction of the flange portion 30c at the same time, or as... Figure 5 As shown in (b), the timing of shearing the flange 30c is varied in the width direction by assigning a shearing angle θ1 to the dressing blade 14. Furthermore, it can also be done as follows... Figure 6 As shown in (a), the flange 30c is sheared parallel to the stamping direction, or as shown in (a). Figure 6 As shown in (b), shearing is performed by using a cam mechanism or similar device to impart an arbitrary shearing angle θ2. In this way, the flange trimming process can be arbitrarily designed to match the envisioned mass production stamping process.

[0045] (Partition trimming process)

[0046] As shown in Figure 4 , the press forming process until the immediately preceding partition plate trimming process, the coil material S is joined together, but in this partition plate trimming process, a trimming upper knife 14 shown in (f) cuts off one hat-shaped cross-sectional member 30 from the joined coil material S. In addition, in the partition plate trimming process, it can be a flat cut that cuts the coil material S linearly at the joining portion with the subsequent hat-shaped cross-sectional member 30 as shown in (a), or it can be a longitudinal cut that cuts the top plate surface 30a, the longitudinal wall portion 30b, and the flange portion 30c at once as shown in (b). Generally, compared with the flat cut, the longitudinal cut is more likely to cause die damage. Figure 3 Figure 7 Figure 7

[0047] [Method of Evaluation]

[0048] Next, the damage evaluation method of the press forming die as one embodiment of the present application will be described.

[0049] In the damage evaluation method of the press forming die as one embodiment of the present application, continuous press forming is performed using the damage evaluation device 1 of the press forming die as one embodiment of the present application. Although it also depends on the specifications of the press device used, for example, in the case where continuous press forming is performed at 20spm (Shots Per Minute) that performs 20 press formings in 1 minute, the time required for 1000 press formings is about 50 minutes or so, and compared with the sliding test, the press forming test as the evaluation method of the die damage, a large number of press forming times can be performed in a short time.

[0050] In addition, in the continuous press forming, press forming can be performed without stopping until the target press forming time, or for example, press forming can be stopped at an arbitrary press forming time of 100 times, 1000 times, 2000 times, 5000 times, or the like, and the evaluation die 10 is taken out to observe the damage behavior of the die steel material of each press forming process. As the observation method using the observation device 100, for example, appearance observation based on photographing, detailed observation based on a portable small microscope, investigation of the amount of wear by copying the shape of the die using a cured resin, or the like, can be arbitrarily decided according to the evaluation purpose.

[0051] In addition, in addition to the observation of the damage behavior of the die steel material corresponding to the press forming time, for example, at least two or more conditions such as the material quality of the die steel material, the presence or absence of a surface coating, the type, or the like can be changed to compare the damage behavior before and after the change, and thereby the material quality of the die steel material, the effectiveness of the surface coating can be evaluated.

[0052] Example

[0053] ​​​In the present embodiment, the hat-shaped cross-sectional member molded by the evaluation mold was shaped with a top panel face width of 50 mm, a vertical wall height of 50 mm, a flange length of 30 mm, and a cross-sectional vertical direction length of 50 mm, and the bend radius of the boundary between the top panel face and the vertical wall portion and the bend radius of the boundary between the vertical wall portion and the flange were 10 mm. In order to join with the hat-shaped cross-sectional members before and after, a joining portion of 10 mm each was provided on the top panel face. A back cut shape of a triangle with a base length of 40 mm, a height of 40 mm, and a protrusion height of 5 mm was imparted to one of the vertical wall portions of the hat-shaped cross-sectional member. The bend radius of the back cut shape portion was 5 mm. The other vertical wall portion was not imparted with a back cut shape. The angle formed by the top panel face and the vertical wall portion and the angle formed by the vertical wall portion and the flange portion were both 90 degrees. The coil material as the object was a non-plated high-tension steel sheet with a tensile strength of 1470 MPa and 980 MPa, and the sheet thickness was 1.4 mm. The width of the coil material was 200 mm according to the molded hat cross-sectional shape.

[0054] The evaluation mold had six press molding processes of a first piercing process, a blanking process, a second piercing process, a bending process, a flange trimming process, and a partition trimming process in order from the direction in which the coil material was fed. The first piercing process punched a hole portion of a diameter of 12 mm in a circular shape in the center of the joining portion of the hat-shaped cross-sectional member, which enabled the insertion of a guide pin for positioning in the subsequent processes. The second piercing process punched a hole portion of a diameter of 7 mm in a circular shape in the center of the top panel face of the hat-shaped cross-sectional member. In the first piercing process and the second piercing process, the clearance (gap) between the piercing punch and the button-type die was 12.5% of the sheet thickness of the coil material.

[0055] In the blanking process, an outer peripheral portion of a "コ" shape with a length of 85 mm and a width of 20 mm was cut out symmetrically to the center of the coil material. The corner portion was an R shape with a radius of 10 mm. The clearance (gap) between the blanking die and the lower die was 12.5% of the sheet thickness of the coil material. In the bending process, the hat-shaped cross-sectional member was molded by pressing the top panel face with a press plate and using a bending die. The press plate force was 5 tons. In the flange trimming process, the flange portions on both sides were cut by about 4 mm from the flange end portion after the hat-shaped cross-sectional member was pressed with a press plate. The press plate force was 5 tons. The cutting angle and the cutting angle were 0 degrees. The clearance between the trimming die and the lower die was 12.5% of the sheet thickness of the coil material. The partition trimming process was a process of cutting the center of the joining portion of the hat-shaped cross-sectional member linearly. The clearance between the trimming die and the lower die was 12.5% of the sheet thickness of the coil material.

[0056] The combinations of the die steel material and the surface treatment of the die for the continuous punching test are shown in Table 1. The continuous punching conditions of No. 1 and No. 2 are compared, whereby the influence of the difference of the die steel material on the die damage behavior can be investigated. The continuous punching conditions of No. 1 and No. 3 are compared, whereby the influence of the difference of the material strength of the coil on the die damage can be investigated. The continuous punching conditions of No. 1 and No. 5 or No. 2 and No. 4 are compared, whereby the influence of the presence or absence of the surface coating on the die damage can be investigated. The continuous punching conditions of No. 5 and No. 6 are compared, whereby the influence of the difference of the kind of the surface coating on the die damage can be investigated. Further, for the die steel material of the bending process, in the case where there is no surface coating, the coil is sintered by several times of the press forming, and therefore the surface coating treatment is implemented for all of the continuous punching conditions.

[0057] [Table 1]

[0058]

[0059] The continuous punching test was implemented using the above-mentioned evaluation die. The press device used was a mechanical press with a pressing capacity of 250 tons, and the continuous press forming was performed at a forming speed of 30 spm. After 1 time of press forming, the coil was fed into the evaluation die at an interval of 70 mm using an uncoiler and straightener. The lubrication of the coil was the same as the rust preventive oil at the time of the coil reception. The continuous punching test was implemented, and after the number of pressings reached 100, 1000, 2000, 5000, 8000, 10000, the evaluation die was taken out of the press device, and the die steel material was observed for the damage behavior. The damage behavior of the die steel material at each observation time is shown in Tables 2 to 8. Table 2 shows the damage behavior of the die steel material in the first piercing process, Table 3 shows the damage behavior of the die steel material in the blanking process, Table 4 shows the damage behavior of the die steel material in the second piercing process, Tables 5 and 6 show the damage behavior of the die steel material in the case where there is a back cut shape and in the case where there is no back cut shape in the bending process, and Tables 7 and 8 show the damage behavior of the die steel material in the case where there is a back cut shape and in the case where there is no back cut shape in the flange trimming process. In the case where there is almost no damage, it was evaluated as O, in the case where there is a slight damage with a damage length of less than 1 mm, it was evaluated as Δ, and in the case where there is a large damage with a damage length of 1 mm or more, it was evaluated as X.

[0060] [Table 2]

[0061]

[0062] [Table 3]

[0063]

[0064] [Table 4]

[0065]

[0066] [Table 5]

[0067]

[0068] [Table 6]

[0069]

[0070] [Table 7]

[0071]

[0072] [Table 8]

[0073]

[0074] According to the above results, it was confirmed that the die damage in each of the press forming processes can be quantitatively evaluated with the same number of press forming as the mass production press. In addition, through the continuous press test in which the combination of the die steel material and the surface coating film of each of the press forming processes was changed, it was confirmed that the higher the material strength of the coil material, the earlier the die damage occurs. Also, it was confirmed that the durability of the die steel material B is superior to that of the die steel material A, and the one with the surface coating film treatment is less likely to be damaged. Also, in the case of the same coil material and die steel material, it was confirmed that the durability of the surface coating film A is superior to that of the surface coating film B. If the forming condition is focused on, the die of the bending tool with the undercut shape is damaged earlier than the bending tool without the undercut shape. This is because the one with the undercut shape is damaged easily because the contact surface pressure between the material and the die during forming is high. In addition, if the shearing condition is focused on, in the flange trimming process, the die of the trimming tool without the undercut shape is damaged earlier than the trimming tool with the undercut shape. No shape is given to the side without the undercut shape, and the rigidity of the vertical wall is low, so the springback of the cross section becomes large compared to the side with the undercut shape. Therefore, the pressure plate is not pressed sufficiently at the time of flange trimming, and becomes unstable shearing such as flange end displacement. Thus, according to the present application, it was confirmed that the die damage occurring due to the mass production press forming of the automobile body frame member or the like using a high-tension steel sheet can be quantitatively evaluated for any die steel material and surface coating film treatment, and the selection criteria of the die steel material and the surface coating film treatment used in the mass production press forming can be provided.

[0075] The above describes embodiments to which the invention completed by the present inventor and others is applied, but the invention is not limited by the description and drawings of the disclosure of the invention involved in the embodiments. That is, other embodiments, examples, and application technologies made by those skilled in the art and others based on the embodiments are all included in the scope of the invention.

[0076] Industrial applicability

[0077] According to the invention, it is possible to provide a damage evaluation device and a damage evaluation method for a press forming die that can quantitatively evaluate damage of the press forming die with respect to any die steel material and coating treatment.

[0078] Explanation of reference numerals

[0079] 1… damage evaluation device for a press forming die; 2… payoff reel; 3… uncoiler; 4… press device; 5… conveyance device; 6… scrap bag; 10… evaluation die; 11… piercing punch; 12… blanking upper die; 13… bending die; 14… trimming upper die; 15… button die; 16… blanking lower die; 17… punch; 18… trimming lower die; 19… platen; 20… hole portion; 21… outer peripheral portion; 30… hat-shaped cross-sectional member; 30a… top plate surface; 30b… vertical wall portion; 30c… flange portion; 30d… undercut shape; 100… observation device; S… coiled material.

Claims

1. A damage evaluation device for stamping dies, characterized in that, Possessing: an evaluation die provided in a press machine that performs press forming on a metal material; and an observation device that observes damage behavior of a die steel material and a surface coating film that constitute the evaluation die, the evaluation die possesses: a piercing unit that forms a hole portion in the metal material; a first shearing unit that shears the metal material in which the hole portion is formed into an arbitrary metal member shape; and a second shearing unit that cuts off a metal member from the metal material, the dies of the piercing unit, the first shearing unit, and the second shearing unit are formed of a die steel material, and have a configuration in which other dies having an arbitrary material and in which an arbitrary surface coating film treatment is implemented can be replaced.

2. The damage evaluation device for a press forming die according to claim 1, characterized in that, the evaluation die possesses: a press forming unit that press forms the metal material after shearing by the first shearing unit into a hat-shaped cross-sectional shape having a top plate surface, a vertical wall portion continuous with the top plate surface, and a flange portion continuous with the vertical wall portion; and a third shearing unit that shears a portion of the flange portion, the dies of the press forming unit and the third shearing unit are formed of a die steel material, and have a configuration in which other dies having an arbitrary material and in which an arbitrary surface coating film treatment is implemented can be replaced, the second shearing unit cuts off a metal member of the hat-shaped cross-sectional shape from the metal material after shearing by the third shearing unit.

3. The damage evaluation device for a press forming die according to claim 2, characterized in that, the hat-shaped cross-sectional shape has a convex shape on one of the vertical wall portions.

4. A damage evaluation method for a press forming die, characterized by including a step of observing damage behavior of a die steel material and a surface coating film that constitute an evaluation die provided in a press machine, after press forming on a metal material has been repeated an arbitrary number of times using the evaluation die, the evaluation die possesses: a piercing unit that forms a hole portion in the metal material; a first shearing unit that shears the metal material in which the hole portion is formed into an arbitrary metal member shape; and a second shearing unit that cuts off a metal member from the metal material, the dies of the piercing unit, the first shearing unit, and the second shearing unit are formed of a die steel material, and have a configuration in which other dies having an arbitrary material and in which an arbitrary surface coating film treatment is implemented can be replaced.

5. The damage evaluation method for a press forming die according to claim 4, characterized in that, the evaluation die possesses: a press forming unit that press forms the metal material after shearing by the first shearing unit into a hat-shaped cross-sectional shape having a top plate surface, a vertical wall portion continuous with the top plate surface, and a flange portion continuous with the vertical wall portion; and a third shearing unit that shears a portion of the flange portion, the dies of the press forming unit and the third shearing unit are formed of a die steel material, and have a configuration in which other dies having an arbitrary material and in which an arbitrary surface coating film treatment is implemented can be replaced, the second shearing unit cuts off a metal member of the hat-shaped cross-sectional shape from the metal material after shearing by the third shearing unit. ​ 6. The damage evaluation method of a press forming die according to claim 5, characterized in that, the hat-shaped cross-sectional shape has a convex shape on one of the longitudinal wall portions.

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