JP-7856901-B2 - Method for creating mold shape data, mold manufacturing method, press-formed product manufacturing method, program, and mold shape data creation system.

JP7856901B2JP 7856901 B2JP7856901 B2JP 7856901B2JP-7856901-B2

Inventors

岩永修一
西村隆一

Assignees

日本製鉄株式会社

Dates

Publication Date: 20260512
Application Date: 20221025

Claims (9)

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 .
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.
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.
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.
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.
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, comprising the characteristics of a mold.
A method for manufacturing press-formed products, A step of manufacturing a mold by the mold manufacturing method described in claim 6 , A method for manufacturing a press-formed product, comprising the step of producing a press-formed product by press-forming a sheet material using the aforementioned mold.
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 .
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 .

Description

This invention relates to a press molding technique using a mold. Generally, a press machine positions the workpiece between one or more dies and press-forms the workpiece into a shape corresponding to the shape of the die's processing surface by bringing the dies closer together until they reach the bottom dead center. After being removed from the die, the press-formed product may change shape due to residual stress at the bottom dead center. This phenomenon is called springback (SB) and can cause a deterioration in dimensional accuracy. As a countermeasure against springback, Japanese Patent Publication No. 6149843 (Patent Document 1) discloses a method for correcting the shape of a press-formed product after demolding by pressing an indenter into it. In this method, a computer identifies regions where residual stresses causing springback exist among the residual stresses before demolding, and then performs a springback analysis after deforming these regions by pressing an indenter into them. The computer determines the indentation location and amount by comparing the shape after indentation with the target shape. Japanese Patent Publication No. 5941320 (Patent Document 2) discloses a die shape simulation system for determining the die shape of a press forming die while anticipating the springback of the molded product. This system uses the finite element method to calculate the residual stress of the molded product at the bottom dead center of the press forming die, and then calculates and displays the shape after springback based on the shape of the molded product at bottom dead center and the residual stress. After displaying the results, the system evaluates whether or not torsion is present. If torsion is present, the system decomposes the residual stress into moment components, in-plane stress components, and out-of-plane stress components, and calculates a corrected residual stress by multiplying each component by a coefficient and combining them. The shape of the molded product after springback, calculated from the shape of the molded product at bottom dead center and the corrected residual stress, is considered the expected die shape for torsion correction. Patent No. 6149843Patent No. 5941320 Figure 1 shows the configuration of the mold shape data creation system in this embodiment.Figure 2 is a flowchart showing an example of the operation of the system shown in Figure 1.Figure 3 is a flowchart showing a detailed example of the processing steps S4 to S5 shown in Figure 2.Figure 4 shows an example of setting the edges and plate sections in the target shape.Figure 5 is a top view of the target shape shown in Figure 4(a) as seen from the z-axis direction.Figure 6 shows an example of the target shape M and prototype S in one cross-section.Figure 7 shows an example of the movement of the prototype.Figure 8 shows an example of movement requests from a user.Figure 9 shows examples of determining the second and third shape differences.Figure 10 shows examples of determining the fourth and fifth shape differences.Figure 11 shows an example of a mold shape indicated by mold shape data.Figure 12 shows examples of the surface shape of the mold before and after modification by the modification section. (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. According to Method 1 described above, the shape difference from the target shape can be determined for each of the two plate sections on either side of the ridge of the prototype, and the mold surface corresponding to each of the two plate sections can be modified based on their respective shape differences. This makes it possible to create mold shape data