Method for creating mold shape data, mold manufacturing method, press-formed product manufacturing method, program, and mold shape data creation system.

Abstract

To bring a press molding close to a target shape while maintaining the shape of a mold corresponding to the press molding within a practical range.SOLUTION: A mold shape data generation method comprises: a step of acquiring mold shape data; a step of acquiring prototype data indicating the shape of a prototype including a ridge line and plate parts of both sides thereof; a step of acquiring target shape data; a step of determining, as a first shape difference, a shape difference between a first plate part of plate parts of both sides of the ridge line of the prototype and a plate part corresponding to the first plate part in the target shape; a step of determining, as a second shape difference, a shape difference between a second plate part of the plate parts of both sides of the ridge line of the prototype and a plate part corresponding to the second plate part in the target shape; a step of correcting the surface of a mold corresponding to the first plate part on the basis of the first shape difference; and a step of correcting the surface of the mold corresponding to the second plate part on the basis of the second shape difference.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a press molding technique using a mold.

Background Art

[0002] Generally, a press device arranges a material to be pressed between one or more molds and brings the one or more molds closer to each other until the bottom dead center, thereby press-molding the material to be pressed into a shape corresponding to the shape of the processing surface of the mold. After the press-molded product is taken out from the mold, its shape may change due to the residual stress at the bottom dead center. This phenomenon is called springback (SB) etc. and causes deterioration of dimensional accuracy.

[0003] As a countermeasure against springback, Japanese Patent No. 6149843 (Patent Document 1) discloses a method of correcting the shape by pushing a punch into a press-molded product after demolding. In this method, a computer identifies a region where there is a factor causing springback among the residual stresses before demolding, performs springback analysis after applying deformation by pushing a punch into this region. The computer determines the punching site and the punching amount of the punch by comparing the shape after the punch is pushed in with the target shape.

[0004] Japanese Patent No. 5941320 (Patent Document 2) discloses a mold shape simulation system that determines the mold shape of a press molding die in anticipation of springback of a molded product. This system calculates the residual stress of the molded product at the bottom dead center of the press molding die using the finite element method, calculates and displays the shape after springback from the shape and residual stress of the molded product at the bottom dead center. After the display, the system obtains an evaluation of the presence or absence of torsion. In the case of torsion, the residual stress is decomposed into a moment component, an in-plane stress component, and an out-of-plane stress component, and a correction residual stress is calculated by multiplying each by a coefficient and synthesizing them. The shape of the molded product after springback calculated from the shape of the molded product at the bottom dead center and the correction residual stress is taken as the shape expected for the torsion correction die.

Prior Art Documents

[0005] [Patent Document 1] Patent No. 6149843 [Patent Document 2] Patent No. 5941320 [Overview of the project] [Problems that the invention aims to solve]

[0006] For example, press-formed products having a hat-shaped cross-section, such as hat members, are formed by bending sheet metal through pressing with a die. Such press-formed products have ridges formed by bending according to the shape of the die. For example, a hat member has ridges between the top plate and the vertical walls, and ridges between the vertical walls and the flanges. The inventors considered determining the shape of the die for press-forming sheet metal into a shape including such ridges and the plate portions on both sides, by calculations that take springback into account. Specifically, they considered calculating the difference vector between the estimated shape of the press-formed product after springback due to residual stress and the target shape, and then displacing the die surface in the opposite direction of the difference vector to determine the die shape that takes springback into account.

[0007] During the investigation, it was found that if a deviation from the target shape occurs in both the plate portions on either side of the ridge of the press-formed product, displacing the die surface in the opposite direction of the difference vector may cause the die shape to fall outside a practical range. For example, the shape of the die ridge (shoulder portion) corresponding to the ridge of the press-formed product may fall outside a practical range. Also, if warping occurs in the plate portion of the press-formed product, the shape of the die surface corresponding to the plate portion may be distorted.

[0008] Therefore, this disclosure provides a method for creating mold shape data that allows a press-formed product to approach a target shape while keeping the shape of the mold corresponding to the press-formed product within a practical range, as well as a method for manufacturing the mold and the press-formed product. [Means for solving the problem]

[0009] A computer-based method for creating mold shape data in an embodiment of the present disclosure includes the steps of: acquiring mold shape data indicating the shape of a mold; acquiring prototype data indicating the shape of a prototype formed from a sheet material by a press using the mold, the prototype including a ridge and the plate portions on both sides thereof; acquiring target shape data indicating the target shape of a press-formed product formed by a press using the mold; determining a first shape difference between a first plate portion, which is one of the plate portions on both sides of the ridge of the prototype indicated by the prototype data, and a plate portion corresponding to the first plate portion in the target shape indicated by the target shape data; determining a second shape difference between a second plate portion, which is the other of the plate portions on both sides of the ridge of the prototype indicated by the prototype data, and a plate portion corresponding to the second plate portion in the target shape indicated by the target shape data; modifying the surface of the mold in the mold shape data corresponding to the first plate portion based on the first shape difference; and modifying the surface of the mold in the mold shape data corresponding to the second plate portion based on the second shape difference. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows the configuration of the mold shape data creation system in this embodiment. [Figure 2] Figure 2 is a flowchart showing an example of the operation of the system shown in Figure 1. [Figure 3] Figure 3 is a flowchart showing a detailed example of the processing in S4-S5 shown in Figure 2. [Figure 4] Figure 4 shows an example of setting the edges and plate sections in the target shape. [Figure 5] Figure 5 is a top view of the target shape shown in Figure 4(a) as seen from the z-axis direction. [Figure 6] Figure 6 shows an example of the target shape M and prototype S in one cross-section. [Figure 7] Figure 7 shows an example of the movement of the prototype. [Figure 8] Figure 8 shows an example of movement requests from a user. [Figure 9] Figure 9 shows examples of determining the second and third shape differences. [Figure 10] Figure 10 shows examples of determining the fourth and fifth shape differences. [Figure 11] Figure 11 shows an example of a mold shape indicated by mold shape data. [Figure 12] Figure 12 shows examples of the surface shape of the mold before and after modification by the modification section. [Modes for carrying out the invention]

[0011] (Method 1) A computer-based method for creating mold shape data in an embodiment of the present disclosure includes the steps of: acquiring mold shape data indicating the shape of a mold; acquiring prototype data indicating the shape of a prototype formed from a sheet material by a press using the mold, the prototype including a ridge and the plate portions on both sides thereof; acquiring target shape data indicating the target shape of a press-formed product formed by a press using the mold; determining a first shape difference between a first plate portion, which is one of the plate portions on both sides of the ridge of the prototype indicated by the prototype data, and a plate portion corresponding to the first plate portion in the target shape indicated by the target shape data; determining a second shape difference between a second plate portion, which is the other of the plate portions on both sides of the ridge of the prototype indicated by the prototype data, and a plate portion corresponding to the second plate portion in the target shape indicated by the target shape data; modifying the surface of the mold in the mold shape data corresponding to the first plate portion based on the first shape difference; and modifying the surface of the mold in the mold shape data corresponding to the second plate portion based on the second shape difference.

[0012] According to the above method 1, for each of the two plate portions on both sides of the ridge line of the prototype, the shape difference from the target shape can be determined, and the surfaces of the molds corresponding to the two plate portions can be corrected based on the respective shape differences. Thereby, while keeping the shape of the mold corresponding to the prototype within a practical range, mold shape data can be created that can bring the press-formed product closer to the target shape.

[0013] The mold shape data, the prototype data, and the target shape data may be data of three-dimensional coordinates representing a three-dimensional shape. The prototype data is, for example, three-dimensional data representing the shapes of the first and second plate portions of the prototype. The prototype data may be three-dimensional data of a plate having a thickness or three-dimensional data of a surface without a thickness. The target shape data is, for example, three-dimensional data representing the shapes of the plate portions corresponding to the first and second plate portions of the target shape. The target shape data may be three-dimensional data of a plate having a thickness or three-dimensional data of a surface without a thickness.

[0014] The first shape difference may be determined, for example, based on the positional relationship between the coordinates of the first plate portion represented by the prototype data and the coordinates of the plate portion of the target shape corresponding to the first plate portion represented by the target shape data in the same coordinate system. The first shape difference may be, for example, a value indicating the positional relationship between the first plate portion and the corresponding plate portion of the target shape in the coordinate system.

[0015] The first shape difference may be, for example, data representing the distance between the surface of the first plate portion and the corresponding plate portion surface of the target shape. As an example, the first shape difference may be represented by the difference in coordinate values in one direction (e.g., the pressing direction) in the coordinate system. Or, it may be represented by a vector indicating the positional relationship between the nodes of the first plate portion and the nodes of the corresponding target shape. Or, the first shape difference may be represented by a value indicating the relationship between the surface of the first plate portion and the corresponding surface of the target shape. The relationship between the surface of the first plate portion and the corresponding surface of the target shape may be represented by, for example, at least one of the movement and deformation between them. As an example, the first shape difference may be a combination of a vector indicating the positional relationship (translation) between the surface of the first plate portion and the corresponding surface of the target shape, and at least one of the amount of twist and the amount of rotation of the surface of the first plate portion with respect to the corresponding surface of the target shape.

[0016] The second shape difference may also be determined based on the positional relationship between the coordinates of the second plate portion represented by the prototype data and the coordinates of the plate portion of the target shape corresponding to the second plate portion represented by the target shape data in the same coordinate system. The second shape difference may be, for example, a value indicating the positional relationship between the second plate portion and the corresponding plate portion of the target shape in the coordinate system.

[0017] Similar to the first shape difference, the second shape difference may also be represented by the distance between two surfaces, the difference in coordinate values in one direction, or the vector between nodes, etc. Or, the second shape difference may be represented by a value indicating the relationship between the surface of the second plate portion and the corresponding surface of the target shape. The relationship between the surface of the second plate portion and the corresponding surface of the target shape may be represented by, for example, at least one of the movement and deformation between them. For example, the second shape difference may be a combination of a vector indicating the positional relationship (translation) between the surface of the second plate portion and the corresponding surface of the target shape, and at least one of the amount of twist and the amount of rotation of the surface of the second plate portion with respect to the corresponding surface of the target shape.

[0018] The target shape shown in the target shape data represents a shape that includes the edge and the plate sections on both sides of it, similar to the prototype data. The plate section corresponding to the first plate section in the target shape is one of the plate sections on either side of the edge in the target shape. The plate section corresponding to the second plate section in the target shape is the other plate section on either side of the edge in the target shape.

[0019] The process of modifying the surface corresponding to the first plate portion of the mold in the mold shape data based on the first shape difference may be, for example, a process of modifying the surface corresponding to the first plate portion of the mold in the mold shape data using a value obtained by multiplying the value indicating the first shape difference by a first coefficient as the modification amount. For example, if the first shape difference is represented by multiple physical quantities, the first coefficient may be set for each physical quantity. As an example, the modification amount may be a value obtained by multiplying the vector, twist amount, and rotation amount representing the first shape difference by individual coefficients. The process of modifying the surface corresponding to the second plate portion of the mold in the mold shape data based on the second shape difference may be, for example, a process of modifying the surface corresponding to the first plate portion of the mold in the mold shape data using a value obtained by multiplying the value indicating the second shape difference by a second coefficient as the modification amount. For example, if the second shape difference is represented by multiple physical quantities, the second coefficient may be set for each physical quantity. As an example, the modification amount may be a value obtained by multiplying the vector, twist amount, and rotation amount representing the second shape difference by individual coefficients. The first coefficient and the second coefficient may each be set independently. This allows the shape of each surface of the mold corresponding to the plate sections on both sides of the ridge to be corrected by an appropriate amount.

[0020] The surface of the mold corresponding to the first plate portion can be the surface of the mold that is in contact with the first plate portion at the bottom dead center. The surface of the mold corresponding to the second plate portion can be the surface of the mold that is in contact with the second plate portion at the bottom dead center.

[0021] The prototype and the press-formed product formed by pressing using the aforementioned die have, as described above, a first plate portion, a second plate portion, and a ridge line between them. The ridge line is a curved portion between the first plate portion and the second plate portion. The ridge line is formed by pressing using the die. The ridge line may be formed, for example, by bending (bent forming) or drawing (draw forming) in the press. The plate portion may, as an example, be a flat plate that is not curved. Alternatively, at least a part of the plate portion may be curved. The plate portion may also include steps or irregularities.

[0022] (Method 2) In the above method 1, the second shape difference, which is the shape difference between the second plate portion of the prototype and the plate portion of the target shape corresponding to the second plate portion, may be determined while the relative position of the prototype with respect to the target shape, as shown in the prototype data, is moved in order to reduce the first shape difference. This allows for a more appropriate determination of the shape difference for both the first plate portion and the second plate portion.

[0023] For example, before determining the second shape difference, the computer may perform the step of moving at least one of the first plate portion or the corresponding plate portion of the target shape in the coordinate system so as to reduce the first shape difference between the first plate portion shown in the prototype data and the corresponding plate portion of the target shape shown in the target shape data.

[0024] (Method 3) In method 1 or 2 described above, the first shape difference may be determined for the cross-sections of the prototype and the target shape on each of the at least two faces intersecting the ridge line. Furthermore, the second shape difference may be determined for the cross-sections of the prototype and the target shape on each of the at least two faces. In this case, the face of the mold corresponding to the first plate portion may be modified in the cross-section of the mold shape on each of the at least two faces, and the face of the mold corresponding to the second plate portion may be modified in the cross-section of the mold shape on each of the at least two faces. This allows for efficient determination of the first and second shape differences and modification of the mold shape data based thereon.

[0025] (Method 4) In method 3 described above, the first shape difference may be determined by calculating a first movement operation that includes a combination of translation and rotation to bring the first plate portion closer to the target shape in the cross-section. This allows for efficient determination of the first shape difference.

[0026] (Method 5) In method 4 described above, the second shape difference may be determined by calculating a second movement operation that moves the second plate portion of the prototype closer to the plate portion of the target shape corresponding to the second plate portion, while the relative position of the prototype with respect to the target shape in the cross-section is moved based on the first movement operation. This allows for efficient determination of the second shape difference. The second movement operation may include, for example, rotational movement.

[0027] (Method 6) In any of the above methods 1 to 5, each step of method 1 may be executed multiple times by a computer. In this case, in the step of acquiring mold shape data for the second time or later, the mold shape data corrected in the previous step may be acquired, and in the step of acquiring prototype data for the second time or later, prototype data showing the shape of a prototype press-formed with a mold that has the shape shown in the mold shape data corrected in the previous step may be acquired. By repeating the correction process using the corrected mold shape data in this way, mold shape data can be obtained that brings the press-formed product closer to the target shape. For example, each step of method 1 can be repeatedly executed until the first shape difference and the second shape difference satisfy predetermined conditions.

[0028] (Method 7) A method for manufacturing a mold using mold shape data created by any of the above methods 1 to 6 is also included in the embodiments of this disclosure. The method for manufacturing a mold comprises the steps of: a computer creating mold shape data by any of the above methods 1 to 8; and manufacturing a mold having the shape indicated by the mold shape data.

[0029] (Method 8) The method for manufacturing a press-formed product in the embodiment of the present disclosure comprises the steps of manufacturing a mold by the mold manufacturing method of Method 7 described above, and manufacturing a press-formed product by press-forming a sheet material using the mold.

[0030] In method 8 described above, in the step of acquiring the prototype data, the computer may acquire the prototype data obtained by measuring the shape of the prototype actually manufactured by press molding using a mold having the shape indicated by the mold shape data. In this case, method 8 may further include the steps of machining the surface of the mold corresponding to the first plate portion so that it becomes the shape of the surface indicated by the mold shape data corrected based on the first shape difference, and machining the surface of the mold corresponding to the second plate portion so that it becomes the shape of the surface indicated by the mold shape data corrected based on the second shape difference. This makes it possible to modify the mold shape data based on the shape difference between the prototype actually manufactured with the mold and the target shape. By machining the mold to the shape indicated by the mold shape data corrected in this way, the press-formed product manufactured by press molding using the mold can be made closer to the target shape. In other words, the dimensional accuracy of the press-formed product can be improved.

[0031] The program in the embodiment of the present disclosure causes the computer to perform the following processes: acquiring mold shape data indicating the shape of a mold; acquiring prototype data indicating the shape of a prototype formed from a sheet material by pressing using the mold, including a ridge and the plate portions on both sides thereof; acquiring target shape data indicating the target shape of a press-formed product formed by pressing using the mold; determining the shape difference between a first plate portion, which is one of the plate portions on both sides of the ridge of the prototype indicated by the prototype data, and a plate portion corresponding to the first plate portion in the target shape indicated by the target shape data, as a first shape difference; determining the shape difference between a second plate portion, which is the other of the plate portions on both sides of the ridge of the prototype indicated by the prototype data, and a plate portion corresponding to the second plate portion in the target shape indicated by the target shape data, as a second shape difference; modifying the surface of the mold in the mold shape data corresponding to the first plate portion based on the first shape difference; and modifying the surface of the mold in the mold shape data corresponding to the second plate portion based on the second shape difference.

[0032] The mold shape data creation system in the embodiment of this disclosure includes: a mold shape data acquisition unit that acquires mold shape data indicating the shape of a mold; a prototype data acquisition unit that acquires prototype data indicating the shape of a prototype formed from a sheet material by pressing using the mold, including a ridge and the plate portions on both sides thereof; a target shape data acquisition unit that acquires target shape data indicating the target shape of a press-formed product formed by pressing using the mold; a first plate portion which is one of the plate portions on both sides of the ridge of the prototype indicated by the prototype data; and the target shape indicated by the target shape data The device comprises: a first shape difference determination unit that determines the shape difference between the first plate portion and the corresponding plate portion as a first shape difference; a second shape difference determination unit that determines the shape difference between the second plate portion, which is the other of the plate portions on both sides of the ridge line of the prototype as shown in the prototype data, and the plate portion corresponding to the second plate portion in the target shape shown in the target shape data as a second shape difference; and a modification unit that modifies the surface of the mold in the mold shape data corresponding to the first plate portion based on the first shape difference, and modifies the surface of the mold in the mold shape data corresponding to the second plate portion based on the second shape difference.

[0033] The embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated. The dimensional ratios between the constituent members shown in each drawing do not necessarily represent the actual dimensional ratios.

[0034] (Example system configuration) Figure 1 shows the configuration of the mold shape data creation system 10 in this embodiment. The mold shape data creation system 10 (hereinafter simply referred to as "system 10") comprises a mold shape data acquisition unit 1, a prototype data acquisition unit 2, a target shape data acquisition unit 3, a first shape difference determination unit 4, a second shape difference determination unit 5, and a modification unit 6. System 10 receives mold shape data indicating the shape of the mold, prototype data indicating the shape of a prototype press-formed with that mold, and target shape data indicating the target shape of the press-formed product, and modifies the mold shape data so that a press-formed product close to the target shape can be obtained.

[0035] The mold shape data acquisition unit 1 acquires mold shape data that indicates the shape of the mold. Upon acquisition, the mold shape data is recorded in a storage unit accessible by the computer constituting the system 10. The mold shape data may be, for example, three-dimensional coordinate data representing the shape of the mold in a three-dimensional orthogonal coordinate system having XYZ axes. The mold shape data may be point cloud data, surface data, or a collection of line data.

[0036] The mold shape data acquisition unit 1 may, for example, acquire mold shape data indicating the initial mold shape from the mold's CAD data (design data). The initial mold shape may be the same as that of a press-formed product, including parts where dimensional accuracy is a concern, or it may be a shape set based on past projected shapes of similar press-formed products. Furthermore, in subsequent processing after the system 10 has modified the initial mold shape data, the mold shape data modified by the system 10 may be acquired. Alternatively, 3D measurement data obtained by measuring a mold processed to the shape indicated by the modified mold shape data may be acquired as mold shape data. In addition, the mold shape data may be created based on target shape data.

[0037] Note that the mold represented by the mold shape data is not limited to a specific shape. In this embodiment, a mold consisting of an upper mold and a lower mold is given as an example. As a variation, the mold represented by the mold shape data may include a pad or a blank holder, etc. In the mold, the shape of the surface that contacts the target press-formed product at the bottom dead center, i.e., the forming surface, is mainly the target of modification processing in system 10.

[0038] The prototype data acquisition unit 2 acquires prototype data indicating the shape of the prototype formed from sheet metal by pressing using a die. Upon acquisition, the prototype data is recorded in a storage unit accessible by the computer constituting the system 10. The prototype shown in the prototype data includes the ridge line formed by pressing using a die and the sheet metal portions on both sides thereof. That is, the prototype has at least one ridge line.

[0039] The prototype data may be, for example, three-dimensional coordinate data representing the shape of the prototype in a three-dimensional orthogonal coordinate system having XYZ axes. The prototype data may also be point cloud data, surface data, or a collection of line data. The prototype data acquisition unit 2 is, for example, data showing the three-dimensional shape of the prototype obtained by actual measurement using a measurement system. Alternatively, it may be data showing the shape of the prototype obtained by a simulation of press forming using a mold shown in the mold shape data.

[0040] The target shape data acquisition unit 3 acquires target shape data. The target shape data is data indicating the target shape of a press-formed product to be formed by a press using a die. Upon acquisition, the target shape data is recorded in a storage unit accessible by the computer constituting the system 10. The target shape is the target shape of a press-formed product to be formed by a press using a die. Therefore, the target shape indicated by the target shape data is a shape that includes at least one edge and the plate portions on both sides of it. The edge and the plate portions on both sides of it in the target shape data correspond one-to-one with the edge and the plate portions on both sides of it of the prototype.

[0041] The target shape data may be, for example, three-dimensional coordinate data representing the target shape of the press-formed product in a three-dimensional orthogonal coordinate system having XYZ axes. The target shape data may be point cloud data, surface data, or a collection of line data. The target shape data acquisition unit 3 may acquire the target shape data from, for example, CAD data (design data) of the press-formed product, CAE analysis results, or data from shape measurements of a prototype produced by pressing.

[0042] The first shape difference determination unit 4 determines the shape difference between a first plate portion, which is one of the plate portions on either side of the edge of the prototype indicated by the prototype data, and the plate portion in the target shape indicated by the target shape data that corresponds to the first plate portion, as the first shape difference. The first shape difference may be determined, for example, by comparing the coordinates of the first plate portion indicated by the prototype data in one coordinate system with the coordinates of the corresponding plate portion indicated by the target shape data. For example, the first shape difference may be a value that indicates at least one of the movement or deformation of the first plate portion in the coordinate system that fits the first plate portion to the corresponding plate portion of the target shape. The movement may include, for example, at least one of translation or rotation. The deformation may include, for example, at least one of torsional deformation or warping deformation.

[0043] The first shape difference determination unit 4 may automatically perform a fitting process between the first plate portion and the corresponding plate portion of the target shape. Alternatively, the first shape difference determination unit 4 may display the first plate portion and the corresponding plate portion of the target shape in a coordinate system on the screen, allowing the user to specify on the screen how to move or deform the first plate portion to fit the target shape.

[0044] Furthermore, as a first shape difference, at least one movement or deformation may be determined for each of the multiple parts included in the first plate portion to fit the corresponding part of the plate portion with the target shape. This part may be, for example, the cross section of the first plate portion, a region of the plate surface, etc.

[0045] The second shape difference determination unit 5 determines the shape difference between the second plate portion, which is the other of the plate portions on either side of the edge of the prototype indicated by the prototype data, and the plate portion corresponding to the second plate portion in the target shape indicated by the target shape data, as the second shape difference. The second shape difference may be determined, for example, by comparing the coordinates of the second plate portion indicated by the prototype data in one coordinate system with the coordinates of the corresponding plate portion indicated by the target shape data. For example, the second shape difference may be determined as a value that indicates at least one of the movement or deformation of the second plate portion such that the second plate portion fits the corresponding plate portion of the target shape in the coordinate system. The movement may include, for example, at least one of translation or rotation. The deformation may include, for example, at least one of torsional deformation or warping deformation.

[0046] The second shape difference determination unit 5 may automatically perform a fitting process between the second plate portion and the corresponding plate portion of the target shape. Alternatively, the second shape difference determination unit 5 may display the second plate portion and the corresponding plate portion of the target shape in a coordinate system on the screen, allowing the user to specify on the screen how to move or deform the second plate portion to fit the target shape.

[0047] Furthermore, as a second shape difference, at least one movement or deformation may be determined for each of the multiple parts included in the second plate portion to fit the corresponding part of the plate portion with the target shape. This part may be, for example, the cross section of the second plate portion, the area of ​​the plate surface, etc.

[0048] The second shape difference determination unit 5 may determine the second shape difference, which is the shape difference between the second plate portion of the prototype and the plate portion of the target shape corresponding to the second plate portion, while moving the relative position of the prototype with respect to the target shape indicated by the prototype data in the coordinate system so as to reduce the first shape difference. For example, the second shape difference between the second plate portion and the corresponding plate portion of the target shape may be determined while moving the first plate portion so as to fit the corresponding plate portion of the target shape.

[0049] In the example shown in Figure 1, system 10 includes a first shape difference determination unit 4 and a second shape difference determination unit 5, but system 10 may also include a third shape difference determination unit, ..., an nth shape difference determination unit. Here, n is a natural number, and n = m + 1. m is the number of edges in the prototype and the target shape.

[0050] The modification unit 6 modifies the surface corresponding to the first plate portion of the mold in the mold shape data based on the first shape difference. The modification unit 6 also modifies the surface corresponding to the second plate portion of the mold in the mold shape data based on the second shape difference. The mold shape shown in the mold shape data has corners or grooves corresponding to the edges of the prototype and target shape, and two surfaces corresponding to the plate portions on both sides of the edges. The two corresponding surfaces of the mold are surfaces that extend on both sides from the corners or grooves. There is a one-to-one correspondence between the edges of the prototype and target shape and the corners or grooves of the mold. There is also a one-to-one correspondence between the plate portions on both sides of the edges of the prototype and target shape and the surfaces of the mold.

[0051] The modification unit 6 determines the modified shape of the corresponding surface of the mold based on the first shape difference. This process may be performed by adding, for example, the value obtained by multiplying the first shape difference of each part of the first plate by a first coefficient to the coordinates of each part of the corresponding surface of the mold. The modification unit 6 determines the modified shape of the corresponding surface of the mold based on the second shape difference. This process may be performed by adding, for example, the value obtained by multiplying the second shape difference of each part of the second plate by a second coefficient to the coordinates of each part of the corresponding surface of the mold.

[0052] System 10 outputs mold shape data corrected by the modification unit 6. The corrected mold shape data may be output to a CAD system or an analysis system. The mold may be machined to achieve the corrected mold shape indicated by the mold shape data. In this case, a prototype is produced again by press forming using the machined mold. Alternatively, a simulation of press forming under the conditions of the corrected mold shape may be performed in the analysis system. In this case, prototype data is generated as the analysis result of press forming using the corrected mold.

[0053] Furthermore, the mold shape data acquisition unit 1 may acquire the mold shape data corrected by the correction unit 6 as mold shape data. In this case, prototype data of a prototype press-formed with the corrected mold shape is acquired by the prototype data acquisition unit 2. The first shape difference determination unit 4 and the second shape difference determination unit 5 determine the first shape difference and the second shape difference based on this prototype data and target shape data. The correction unit 6 corrects the mold shape data based on the first shape difference and the second shape difference. In this way, the mold shape data correction process can be repeatedly executed using the corrected mold shape data and the prototype data of a prototype press-formed with the corrected mold. This allows the mold shape indicated by the mold shape data to converge so that a press-formed product closer to the target shape can be obtained. Note that a first coefficient and a second coefficient may be set in each of the repeated correction processes. The first coefficient and the second coefficient may be determined, for example, based on the first shape difference and the second shape difference. By determining the first coefficient and the second coefficient according to the first shape difference and the second shape difference, the mold shape of the mold shape data becomes easier to converge.

[0054] System 10 consists of one or more computers equipped with a processor and memory. The functions of the mold shape data acquisition unit 1, prototype data acquisition unit 2, target shape data acquisition unit 3, first shape difference determination unit 4, second shape difference determination unit 5, and modification unit 15 can be realized by the processor executing a predetermined program. Such a program and a non-transitory storage medium storing it are also included in embodiments of this disclosure.

[0055] (Example of operation) Figure 2 is a flowchart illustrating an example of the system's operation shown in Figure 1. In the example shown in Figure 2, the target shape data acquisition unit 3 acquires target shape data (S1). The target shape data acquisition unit 3 reads, for example, CAD data (design data) of the target shape from a CAD system and records it in a storage unit accessible by the computer of system 10. The target shape data acquisition unit 3 may convert the CAD data as needed.

[0056] The mold shape data acquisition unit 1 acquires mold shape data (S2). For the first time, the mold shape data acquisition unit 1 reads the CAD data (design data) of the mold from the CAD system as the initial mold shape data. For subsequent S2s, it reads the mold shape data that has been modified by the modification unit 6 in S5, which will be described later. If there is no mold shape data for the first time, the mold shape can be generated from target shape data. For example, a shape offset from the target shape, taking into account the thickness of the material, can be generated as the shape of the mold surface. Thus, the initial mold shape data may be equivalent to the target shape.

[0057] The prototype data acquisition unit 2 acquires prototype data (S3). The prototype data may be shape data obtained by measuring a prototype that has been press-formed with a mold having the shape indicated by the mold shape data. Alternatively, it may be data showing the shape of the prototype calculated by a simulation of press-forming with a mold having the shape indicated by the mold shape data. In subsequent S3s, the prototype shape data obtained in S6, described later, by press-forming with a modified mold or by analysis is read.

[0058] In S4, the first shape difference determination unit 4 determines the first shape difference between the first plate portion and the target shape among the plate portions on both sides of the ridge of the prototype, and the second shape difference determination unit 5 determines the second shape difference between the second plate portion and the target shape among the plate portions on both sides of the ridge of the prototype. If the prototype has two or more ridges, the shape difference between each ridge and the target shape of the plate portions on both sides of it is determined. If there are m ridges to be processed, the shape difference between each of the first to nth plate portions (n=m+1) and the target shape is determined. That is, the first to nth shape differences are determined.

[0059] Furthermore, when determining the k-th shape difference (k=2, 3, ..., n), the k-th shape difference between the k-th plate material and the corresponding plate portion of the target shape may be determined while the k-th member is moved to reduce the k-th shape difference. This allows for the appropriate determination of the 1st to nth shape differences.

[0060] In S5, the modification unit 6 modifies the corresponding surface of the mold indicated by the mold shape data for the first to nth plate sections using the first to nth shape differences. In this case, the corresponding surface of the mold to be modified is also the nth surface.

[0061] In S6, system 10 provides the mold shape data modified in S5 to, for example, a CAE system. The CAE system performs a simulation of press forming using the modified mold. As an analysis result, shape data of a molded product (prototype) press-formed with the modified mold is generated. Alternatively, the mold shape data modified in S5 may be provided to a mold processing system. In this case, in S6, shape data of a prototype produced by press forming using a mold with the shape indicated by the modified mold shape data is obtained.

[0062] If the prototype obtained by press forming using the modified mold shape or by CAE analysis satisfies the pre-set conditions (YES in S7), the process terminates. The conditions may be, for example, that the shape of the prototype is equivalent to the target shape. The criteria for "equivalent" may be set as appropriate, but for example, the distance between the target shape and the prototype shape at a node at a user-specified position among the first to nth shape differences is less than or equal to a threshold (for example, a distance of 0.1 mm or less). Alternatively, the design condition may be that the difference in partial curvature between the prototype and the target shape is below a threshold.

[0063] Figure 3 is a flowchart showing a detailed processing example in S4-S5 as shown in Figure 2. In the example in Figure 3, system 10 determines the edges and plate portions in the target shape and mold shape in the target shape data and mold shape data (S11). For example, in the target shape, the areas of the edges and plate portions are determined. For example, the edges and plate portions in the target shape may be determined based on the position of the edges or plate portions defined in the CAD data of the target shape, or the position of the curved portion of the design edge (the position where the radius ends). In the mold shape, the edges and plate portions can be determined in the same way as in the target shape.

[0064] Figure 4 shows an example of setting the edges and plate sections in the target shape. In the example shown in Figure 4(a), the target shape M is the shape of a hat member, where the cross section perpendicular to the longitudinal direction (extension direction) is hat-shaped. The hat member has a top plate T1, two vertical walls T2 and T3 extending from both ends of the top plate T1, and flanges T4 and T5 extending from the ends of the vertical walls T2 and T3 opposite to the top plate T1. There are edges R2 and R3 between the top plate T1 and the vertical walls T2 and T3, and edges R1 and R4 between the vertical walls T2 and T3 and the flanges T4 and T5. T1 to T5 are examples of plate sections corresponding to the first to fifth plate sections. In the example in Figure 4(a), the target shape is the shape of a surface without thickness, but the target shape may also be the shape of a structure with thickness.

[0065] Note that the target shape is not limited to a cross-sectional hat shape. Figures 4(b) to 4(e) show modified examples of the target shape and the setting of the edges and plate sections. In Figures 4(b) to 4(e), T1 to T7 are examples of plate sections set in the target shape M. Note that in (b) to (d), each plate section is a flat plate that is not curved. Plate sections may be curved, or may include steps or irregularities. For example, as shown in plate section T1 in Figure 4(e), a portion including a recess can be set as a single plate section.

[0066] In the example in Figure 4(a), the plate sections on both sides of lines R1 to R4 are set as the 1st to 5th plate sections T1 to T5. The positions of the edges R1 to R4 may be determined, for example, based on the positions of the edges defined in the CAD data, or they may be determined based on user specifications. In the example in Figure 4(a), the edges R1 to R4 are defined as lines, but the edges R1 to R4 may also be defined as surfaces or solids.

[0067] In S11 of Figure 3, the edges and plate sections of the prototype can be set in the prototype data, similar to the target shape. If the target shape is a hat-shaped member as shown in Figure 4(a), the prototype will also be a hat-shaped member having a top plate, two vertical walls, and two flanges. Here, as an example, the top plate of the prototype is designated as the first plate section, the two vertical walls as the second and third plate sections, and the two flanges as the fourth and fifth plate sections.

[0068] In S11 of Figure 3, similar to the target shape, the mold shape data can be set to define the surfaces corresponding to the first to nth plate sections of the mold. If the target shape is a hat member as shown in Figure 4(a), the mold will have a shape that has surfaces corresponding to each plate section of the hat member, i.e., the top plate, the two vertical walls, and the two flanges.

[0069] In S12, system 10 places the target shape, prototype, and mold shape in a single coordinate system. That is, alignment is performed to determine the positions of the target shape, prototype, and mold shape in the coordinate system. For example, their positions in the coordinate system can be determined so that one longitudinal end of the target shape coincides with one longitudinal end of the prototype. The alignment is not particularly limited, but examples include a method of determining the positions of the target shape, prototype, and mold shape so that reference surfaces, axes, or points set for them align, or a method of determining the position where the sum of errors between the point cloud data of the whole or part of the prototype and the target shape is minimized (e.g., best fit).

[0070] In S13, system 10 sets up multiple cross-sections in the coordinate system that are common to the target shape, prototype, and mold shape. Figure 5 is a top view of the target shape shown in Figure 4(a) as seen from the z-axis direction. In the example in Figure 5, multiple surfaces perpendicular to the edges R2 and R3 and arranged at predetermined intervals (e.g., 1 mm) are set as cross-section D. Cross-sectional data for the target shape, prototype, and mold shape are created for each of the multiple cross-sections.

[0071] In S14 of Figure 3, the system 10 acquires data (e.g., point cloud data) of the target shape, prototype, and mold shape at the cross section set in S13. In S15, the cross section to be processed for the first time is selected from the cross sections set in S13. The cross section for calculating the shape difference may be selected automatically or based on user input.

[0072] Figure 6 shows an example of the target shape M and prototype S in one of the cross-sections used to calculate the shape difference. In the example in Figure 6, the top plate Ts1 of prototype S is the first plate section, and the top plate T1 of the target shape is the plate section corresponding to the first plate section. The top plate T1 is the part between the edges R2 and R3. The top plate Ts1 of prototype S is the part between the edges Rs2 and Rs3. The positions of the edges Rs2 and Rs3 of prototype S may be determined based on user specifications. Alternatively, the positions of the edges Rs2, Rs3 and the top plate Ts1 may be automatically determined based on the shape of prototype S or the positions of the edges R2 and R3 of the target shape as image-recognized in the cross-section. The vertical wall Ts2 of prototype S is the second plate section, and the vertical wall T2 of the target shape M is the plate section corresponding to the second plate section. The vertical wall Ts2 is the part between the edges Rs3 and Rs4. The positions of ridges Rs3 and Rs4 may be determined by user specification, image recognition, or based on the positions of ridges Rs3 and Rs4.

[0073] In S16 of Figure 3, the first shape difference determination unit 4 determines the shape difference between the top plate Ts1 of the prototype S and the top plate T1 of the target shape in cross-section. The first shape difference determination unit 4 moves the prototype S so that the top plate Ts1 of the prototype S fits the top plate T1 of the target shape in cross-section. Figure 7 shows an example of the movement of the prototype. In the example shown in Figure 7, first, the prototype S is translated in the z direction so that one representative point of the top plate Ts1 of the prototype S (for example, the edge line Rs2, which is one end of the top plate Ts1) is closest to the target shape in the z direction (Figures 7(a) to (b), amount of movement in the z direction: ΔZweb1). Then, the prototype S is rotated around the representative point. The prototype S is rotated so that the other end of the top plate Ts1 (edge ​​line Rs3) is closest to the top plate T1 of the target shape (Figures 7(b) to (c), rotation angle: Δθweb1). These movements can be automatically determined by the first shape difference determination unit 4 based on the coordinates of the representative point.

[0074] In S16, the first shape difference determination unit 4 may further accept from the user at least one of the movement or deformation of the prototype S relative to the target shape M. Figure 8 shows an example of movement accepted from the user. In the example in Figure 8, the prototype S and the target shape are displayed superimposed in cross-section. The user can select the prototype S on the screen and input a movement instruction. For example, the user can specify the direction and distance of the translation of the prototype (ΔXweb2, ΔZweb2), and the axis of rotation and angle of rotation (axis of rotation L5, angle θweb2). As a result, the prototype S moves, for example, from (a) to (b) in Figure 8.

[0075] Thus, when both automatic and manual movement by the user are accepted, the combined movement of the automatic and manual movements is determined as the first shape difference. However, the first shape difference may also be determined by either the automatic or manual movement alone.

[0076] In step S17 of Figure 3, if there is an unprocessed plate section, the system 10 selects the next plate section (second plate section) as the target, and in the process of S16, determines the shape difference (second shape difference) between the selected plate section (second plate section) and the corresponding plate section of the target shape. Figure 9 shows an example of determining the second and third shape differences. In the example shown in Figure 9, the shape difference between the second plate section, i.e., the vertical wall Ts2, and the vertical wall T2 of the target shape M is determined after moving the prototype S used to determine the first shape difference. As a specific example, the vertical wall Ts2 is rotated around the end (ridge line Rs3) on the top plate Ts1 side of the vertical wall Ts2. The rotation angle Δθwall-R is, for example, the angle at which the flange side end (ridge line Rs4) of the vertical wall Ts2 is closest to the target shape. This rotation angle Δθwall-R is determined as the second shape difference.

[0077] Figure 9 shows an example where, similarly, for the vertical wall Ts3 of the prototype S, which is the third plate section, the rotation angle Δθwall-L for the rotational movement that brings the vertical wall Ts3 closer to the vertical wall T3 is determined as the third shape difference.

[0078] Figure 10 shows an example of determining the fourth and fifth shape differences. In the example in Figure 10, the flange Ts4 is rotated around its vertical wall end (ridge line Rs4). The rotation angle θfrange-R can be the angle at which the tip of the flange Ts4 is closest to the target shape. This rotation angle θfrange-R is determined as the fourth shape difference. Similarly, the rotation angle θfrange-L is determined as the fifth shape difference.

[0079] In this way, the first to fifth shape differences are calculated for each of the first to fifth plate sections. If there are any unprocessed sections among the sections set in S13 (YES in S18), the system 10 selects them as the target for the next section. For the next section, the process of determining the first to fifth shape differences (S16 to S17) is executed.

[0080] The fitting process for determining the shape difference between the plate portion of prototype S and the plate portion of the target shape is not limited to the above example. For example, by obtaining perpendicular (nearest point) vectors between the plate portion of the molded product and the corresponding plate portion of the target shape, the translation and rotation angles can be calculated by fitting the prototype to minimize the integral value (the square of the norm of the vector). In addition to the translation and rotation of the prototype, the deformation of the prototype (e.g., warp) may also be calculated during the fitting process. Furthermore, instead of the translation or deformation of the prototype, the translation or deformation of the target shape, or both the prototype and the target shape, may be calculated.

[0081] Once the shape difference determination process is completed for all the cross-sections set in S13 (NO in S18), the modification unit 6 modifies the mold shape data for each cross-section based on the first to fifth shape differences determined in S16 (S19). In S19, the modification unit 6 modifies the surfaces corresponding to the target plate sections (first to fifth plate sections) in the mold shape data for each cross-section.

[0082] Figure 11 shows an example of a mold shape indicated by mold shape data. The mold shape shown in Figure 11 has surfaces Tk1 to Tk5 corresponding to each of the plate portions T1 to T5 in the target shape shown in Figure 4(a). That is, at the bottom dead center, the mold shape has a surface Tk1 that contacts the top plate Ts1, two surfaces Tk2 and Tk3 that contact the two vertical walls Ts2 and Ts3, and two surfaces Tk4 and Ts5 that contact the two flanges Ts4 and Ts5. The surfaces Tk1 to Tk5 of the mold shape may be determined, for example, based on the positions of the mold edges Rk1 to Rk4. The positions of the edges Rk1 to Rk4 may be based, for example, on the positions of the edges defined in the mold's CAD data. Alternatively, the positions of the edges or each surface may be determined based on user specification, image processing, or the target shape.

[0083] Figure 12 shows examples of the mold shape surfaces before and after modification by the modification unit 6. In the process of S19, the modification unit 6 modifies the corresponding surfaces Tk1, Tk2, Tk3, Tk4, and Tk5 of the top plate Ts1, vertical walls Ts2 and Ts3, and flanges Ts4 and Ts5, respectively. The amount of modification for each surface Tk1 to Tk5 can be the value obtained by multiplying the amount of movement of the first to fifth shape differences by a coefficient. Normally, the direction of movement calculated as the first to fifth shape differences and the direction of modification of the mold surface are opposite. In this case, the modification unit 6 can displace the mold surface by an amount corresponding to the amount of movement in the opposite direction to the direction of movement of the shape difference. In this case, the coefficient can be a negative value. The coefficient may be set for each direction of movement or rotational movement. For example, in the examples shown in Figures 7 and 8, the movement determined as the first shape difference of the top plate Ts1 includes three types of movement: translation in the x direction, translation in the z direction, and rotation with the y direction as the central axis. For each of these three types of movement, the amount obtained by multiplying it by a coefficient can be used as the amount of correction to the mold surface Tk1.

[0084] In the example shown in Figure 12, the sum of the values ​​obtained by multiplying the rotation angle θweb of the top plate Ts1 by coefficient N1, the value obtained by multiplying the movement in the x-direction by coefficient N2, and the value obtained by multiplying the movement in the z-direction by coefficient N3 represents the amount of correction to the mold surface corresponding to the top plate Ts1. In this way, by setting coefficients for each movement direction or rotational movement, an appropriate amount of correction can be determined. In this manner, a mold shape that can minimize shape differences can be determined. In Figure 12, N1 to N3 are examples of first coefficients for the first plate section, and N3 is an example of a second coefficient for the second plate section. The coefficients N1 to N5 in Figure 12 are all coefficients for the amount of movement. For example, if any of the first to N shape differences include deformation, the amount of correction to the mold may be further determined by multiplying the deformation amount by a coefficient.

[0085] In step S19 of Figure 3, for each cross-section, a process is executed to modify the mold shape data of the mold surface corresponding to each plate portion. This determines the expected mold shape for each of the multiple cross-sections.

[0086] According to this embodiment, it is possible to create mold shape data that can improve dimensional accuracy in press-formed products having ridges. Therefore, by press-forming using a mold with the shape indicated by this mold shape data, it is possible to manufacture a press-formed product that is close to the target shape. A method for manufacturing a mold with the shape indicated by the mold shape data, and a method for manufacturing a press-formed product using that mold are also included in the embodiments of this disclosure.

[0087] Furthermore, for example, dimensional inaccuracies due to springback in press-formed products with ridges may be caused by a combination of longitudinal warping or twisting of the press-formed product and angular changes or warping of the plate portions on both sides of the ridge within a cross-section perpendicular to the longitudinal direction of the press-formed product. If the mold surface is displaced in the opposite direction of the difference vector based on conventional technology to compensate for the shape difference from the target shape due to such complex factors, the mold may lose its practical shape. For example, if there are significant shape differences in both the plate portions on both sides of the ridge, reflecting these shape differences in the mold may cause the shape of the mold shoulder to collapse. Alternatively, if the angular changes and warping of the plate portions are large, reflecting these shape differences in the mold may cause the shape of the mold surface corresponding to the plate portion to collapse. In contrast, in this embodiment, the shape difference is determined for each of the plate portions on both sides of the ridge of the prototype, and the mold surface corresponding to each of these plate portions is modified based on the shape difference. This allows the press-formed product to approach the target shape while maintaining the mold shape within a practical range, even when shape differences occur due to multiple factors.

[0088] This embodiment is not limited to these examples, but can be suitably applied to molds used for press forming of various automobile body parts, such as pillars, members, and side sills. In recent years, there has been a demand for lighter vehicle bodies to reduce carbon dioxide in exhaust gases and improve fuel efficiency. To achieve both lightness and strength as materials for automobile frame parts, the application of high-strength steel sheets is expanding. High-strength steel sheets are prone to springback (SB) due to residual stress during press forming. One of the challenges in applying high-strength steel sheets to automobile frame parts is that dimensional inaccuracies due to springback occur when processing high-strength steel sheets into members by press forming. For example, in the case of a front side member with a hat cross-section, "bouncing" (angle change at the punch shoulder and die shoulder) occurs in the vertical wall and flange, resulting in a deterioration of dimensional accuracy. As materials become stronger, similar difficult challenges exist in various frame parts.

[0089] The mold shape data creation method of this embodiment can solve these problems. In conventional methods for determining mold shape using numerical analysis of residual stress, it was difficult to adequately address the issue through numerical analysis before actually manufacturing the mold. Therefore, prototyping and mold modification were required after mold manufacturing. In this embodiment, the expected mold shape to approach the target shape of the press-formed product can be determined with high accuracy while keeping the mold shape within a practical range. Therefore, for example, it becomes possible to improve dimensional accuracy by utilizing numerical analysis before mold manufacturing in the production preparation stage.

[0090] Although one embodiment of the present invention has been described above, the above-described embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and it is possible to carry out the above-described embodiment by appropriately modifying it without departing from the spirit of the present invention. [Explanation of Symbols]

[0091] 10. Mold Shape Data Creation System 1. Mold shape data acquisition unit 2. Prototype data acquisition unit 3. Target shape data acquisition unit 4. First shape difference determination unit 5. Second shape difference determination section 6 Correction section

Claims

1. A method for creating mold shape data performed by a computer, Steps include obtaining mold shape data that shows the shape of the mold, A prototype formed from a sheet material by pressing using the aforementioned die, a step of acquiring prototype data that shows the shape of the prototype including the ridge line and the sheet portions on both sides thereof, The steps include: acquiring target shape data that indicates the target shape of a press-formed product formed by pressing using the aforementioned die; The steps include determining the first shape difference between a first plate portion, which is one of the plate portions on both sides of the ridge of the prototype as shown in the prototype data, and a plate portion corresponding to the first plate portion in the target shape shown in the target shape data, as the first shape difference; The steps include determining the second shape difference between the second plate portion, which is the other of the plate portions on both sides of the ridge of the prototype as shown in the prototype data, and the plate portion corresponding to the second plate portion in the target shape shown in the target shape data, A step of modifying the surface of the mold corresponding to the first plate portion in the mold shape data based on the first shape difference, A step of modifying the surface of the mold corresponding to the second plate portion in the mold shape data based on the second shape difference, It has, A method for creating mold shape data, wherein the relative position of the prototype with respect to the target shape, as shown in the prototype data, is moved to reduce the first shape difference, and the second shape difference is determined, which is the shape difference between the second plate portion of the prototype and the plate portion of the target shape corresponding to the second plate portion.

2. A method for creating mold shape data according to claim 1, The first shape difference is determined for the cross-sections of the prototype and the target shape at each of the at least two faces intersecting the aforementioned ridge line. The second shape difference is determined for the cross-sections of the prototype and the target shape on each of the at least two surfaces. In the cross-section of the mold shape on each of the at least two surfaces, the surface of the mold corresponding to the first plate portion is modified. A method for creating mold shape data, which involves modifying the surface of the mold corresponding to the second plate portion in the cross-section of the mold shape on each of the at least two surfaces.

3. A method for creating mold shape data according to claim 2, A method for creating mold shape data, wherein the first shape difference is determined by calculating a first movement operation that includes a combination of translation and rotation to bring the first plate portion closer to the target shape in the cross-section.

4. A method for creating mold shape data according to claim 3, A method for creating mold shape data, wherein the second shape difference is determined by calculating a second movement operation that brings the second plate portion of the prototype closer to the plate portion of the target shape corresponding to the second plate portion, while the relative position of the prototype with respect to the target shape in the cross-section is moved based on the first movement operation.

5. A method for creating mold shape data according to claim 1 or 2, Each step described in claim 1 is performed multiple times by a computer, In the second and subsequent steps for acquiring mold shape data, the mold shape data that was modified in the previous step is acquired. In the step of acquiring prototype data for the second and subsequent prototypes, prototype data is acquired that shows the shape of the prototype press-formed using a mold with the shape indicated by the mold shape data that was modified in the previous step. How to create mold shape data.

6. A method for manufacturing a mold, A step in which a computer creates mold shape data using the mold shape data creation method described in claim 1 or 2, The steps include: manufacturing a mold having the shape indicated by the mold shape data; A method for manufacturing a mold, having the following characteristics.

7. A method for manufacturing press-formed products, A step of manufacturing a mold by the mold manufacturing method described in claim 6, The steps include: producing a press-formed product by press-forming a sheet material using the aforementioned mold; A method for manufacturing press-formed products having the following characteristics.

8. A process to acquire mold shape data that shows the shape of the mold, A process for acquiring prototype data that shows the shape of a prototype formed from a sheet material by pressing using the aforementioned die, including the ridge line and the sheet portions on both sides thereof, A process for acquiring target shape data that indicates the target shape of a press-formed product formed by pressing using the aforementioned die, A process to determine the shape difference between a first plate portion, which is one of the plate portions on both sides of the ridge of the prototype as shown in the prototype data, and a plate portion corresponding to the first plate portion in the target shape shown in the target shape data, as the first shape difference; A process to determine the shape difference between the second plate portion, which is the other of the plate portions on both sides of the ridge line of the prototype as shown in the prototype data, and the plate portion corresponding to the second plate portion in the target shape shown in the target shape data, as the second shape difference; A process to modify the surface of the mold corresponding to the first plate portion of the mold in the mold shape data based on the first shape difference, A process to modify the surface of the mold corresponding to the second plate portion in the mold shape data based on the second shape difference, Have the computer run it, A program that determines the second shape difference, which is the shape difference between the second plate portion of the prototype and the plate portion of the target shape corresponding to the second plate portion, while moving the relative position of the prototype with respect to the target shape, as shown in the prototype data, in order to reduce the first shape difference.

9. A mold shape data acquisition unit acquires mold shape data that shows the shape of the mold, A prototype formed from a sheet material by pressing using the aforementioned mold, comprising a prototype data acquisition unit that acquires prototype data indicating the shape of the prototype including the ridge line and the plate portions on both sides thereof, A target shape data acquisition unit acquires target shape data indicating the target shape of a press-formed product formed by pressing using the aforementioned die, A first shape difference determination unit determines the shape difference between a first plate portion, which is one of the plate portions on both sides of the ridge of the prototype as shown in the prototype data, and a plate portion corresponding to the first plate portion in the target shape shown in the target shape data, as the first shape difference. A second shape difference determination unit determines the shape difference between the second plate portion, which is the other of the plate portions on both sides of the ridge line of the prototype as shown in the prototype data, and the plate portion corresponding to the second plate portion in the target shape shown in the target shape data, as the second shape difference. Based on the first shape difference, the surface corresponding to the first plate portion of the mold in the mold shape data is modified. A modification unit that modifies the surface of the mold corresponding to the second plate portion in the mold shape data based on the second shape difference, Equipped with, The second shape difference determination unit is a mold shape data creation system that determines the second shape difference, which is the shape difference between the second plate portion of the prototype and the plate portion of the target shape corresponding to the second plate portion, while moving the relative position of the prototype with respect to the target shape, as shown in the prototype data, so as to reduce the first shape difference.

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