Method for manufacturing a stamped part, method for designing a metal mold, metal mold shape design device, and metal mold

Abstract

This invention provides a method for manufacturing stamped parts that can be applied even when manufacturing stamped part shapes that cannot be formed without significant deep drawing. When a sheet metal is stamped into a final part shape through two or more stamping processes including a stamping step, the amount of material flow required to form the final part shape is calculated based on the increase in the cross-sectional length of the final part shape relative to the initial shape when the sheet metal is stamped into the final part shape in a single stamping step. This calculated amount of material flow is allocated to each process including the final stamping step, and the pre-formed shape after stamping in processes other than the final stamping step is determined based on the allocated amount of material flow. As a cross-section, a line orthogonal to the direction of material flow during deep drawing of the sheet metal is defined, and multiple cross-sections are defined, each cut by a plane orthogonal to this line in the view and extending along the thickness direction of the sheet metal before forming.

Description

Technical Field

[0001] The present invention relates to a technique for manufacturing a target stamped part in a series of stamping processes including deep drawing. Background Technology

[0002] In recent years, considering factors such as lightweighting, aerodynamic performance, design, and crash safety, the performance requirements for automotive components have become increasingly stringent. This necessitates the manufacture of parts with shapes that are difficult to form using conventional stamping methods. Furthermore, due to factors such as vehicle pricing, resource conservation, and CO2 reduction, there is a need to reduce the amount of material used in product manufacturing—in other words, to increase material yield.

[0003] As methods for improving formability in stamping, there are, for example, the methods described in Patent Document 1 and Patent Document 2. Patent Document 1 discloses a method for improving formability by appropriately shaping the metal die for each step in a multi-step stamping process. Furthermore, Patent Document 2 discloses a method that allows a localized area of ​​the stamping die to be driven as a separate movable punch. Moreover, Patent Document 2 discloses a method for pre-loading the blank into the die and then forming it using the aforementioned movable punch, thereby avoiding poor forming.

[0004] Patent Document 1: Japanese Patent No. 5867657

[0005] Patent Document 2: Japanese Patent Application Publication No. 2007-326112

[0006] The method described in Patent Document 1 targets protruding forming or deep drawing protruding forming with a small inflow amount. However, the method described in Patent Document 1 is difficult to apply to part shapes that cannot be formed without significant deep drawing. Specifically, the method described in Patent Document 1 is difficult to apply when forming a part in which the increase in the line length of the final shape relative to the initial state far exceeds the uniform elongation of the material.

[0007] The method described in Patent Document 2 applies pressure while forming a pre-positioned area using a movable punch. Therefore, no further material movement or deformation occurs at the pressurized area, resulting in limited effectiveness. Furthermore, Patent Document 2 does not disclose detailed design methods for the metal mold, or the setting range of the movable punch. Summary of the Invention

[0008] The present invention was made with regard to the points mentioned above, and aims to provide a method for manufacturing stamped parts and a method for designing metal molds that can be applied even when manufacturing stamped parts that cannot be formed without significant deep drawing.

[0009] To address the problem, one aspect of the present invention is a method for manufacturing a stamped part by stamping a metal sheet into a final part shape through multiple stamping processes. The method selects one of the multiple stamping processes as a selection process, and uses the part shape obtained in that selection process as the selected part shape. A stamping process selected from the multiple stamping processes and performed before the selection process is used as a reference process, and the shape of the metal sheet before stamping in that reference process is used as the reference shape. The stamping process from the reference process to the selection process includes a deep-drawing process. The method further comprises: a profile setting process, in which lines are set orthogonal to the direction of material flow when the metal sheet of the reference shape is deep-drawn into the selected part shape in one process, and lines are set to be orthogonal to the lines in the top view and along the metal sheet before forming. The process includes: a planar section extending in the thickness direction of the sheet metal; an inflow calculation step, which, for each section, calculates the amount of material required to form the reference shape into the selected component shape based on the section line length of the selected component shape cut by the section, the section line length of the reference shape cut by the same section, and the uniform elongation of the material of the sheet metal; an inflow allocation step, which allocates the calculated inflow amount to each process from the reference process to the selected process, based on each section; a section line length calculation step, which calculates the section line length of each section in each process up to the previous process from the reference process to the selected process, based on the allocated inflow amount; and a shape determination step, which determines the preformed shape after stamping in each process up to the previous process from the reference process to the selected process, based on the calculated section line length.

[0010] Furthermore, the main point of this invention is a method for designing a metal mold used when stamping a metal sheet into a final part shape through multiple stamping processes. This method selects one of the multiple stamping processes as the selected process, takes the part shape obtained in that selected process as the selected part shape, selects a stamping process performed before the selected process as the reference process, and takes the shape of the metal sheet before stamping in that reference process as the reference shape. In the stamping process from the reference process to the selected process, a deep-drawing stamping process is included. The metal mold design method comprises: a profile setting process, setting a line orthogonal to the direction of material flow when the metal sheet of the reference shape is deep-drawn into the selected part shape in a single process, and setting lines orthogonal to the lines in a single view and along the metal sheet before forming. The process includes: a plane cutting multiple sections extending in the thickness direction; an inflow calculation step, which, for each section, calculates the amount of material required to form the reference shape into the selected component shape based on the section line length of the selected component shape cut by the section, the section line length of the reference shape cut by the same section, and the uniform elongation of the metal sheet material; an inflow allocation step, which allocates the calculated inflow amount to each process from the reference process to the selected process, based on each section; a section line length calculation step, which calculates the section line length of each section in each process up to the previous process from the reference process to the selected process, based on the allocated inflow amount; and a shape determination step, which determines the shape of the metal mold used in each process up to the previous process from the reference process to the selected process, based on the calculated section line length.

[0011] Furthermore, the main purpose of this invention is to determine the shape of the metal mold used in each of the stamping processes other than the final stamping process when a metal sheet is stamped into a final part shape through multiple stamping processes. The invention involves selecting one of the multiple stamping processes as the selected process, using the part shape obtained in that selected process as the selected part shape, selecting a stamping process performed before the selected process as the reference process, and using the shape of the metal sheet before stamping in that reference process as the reference shape. In the stamping process from the reference process to the selected process, a deep-drawing stamping process is included. The metal mold shape design apparatus includes a profile setting section that sets a line orthogonal to the direction of material flow when the metal sheet of the reference shape is deep-drawn into the selected part shape in one process, and sets lines that are respectively set to the direction of material flow when viewed from above. The system comprises: a plurality of cross-sections cut by a plane orthogonal to the aforementioned line and extending along the thickness direction of the metal sheet before forming; an inflow calculation unit, for each cross-section, calculating the amount of material required to form the reference shape into the shape of the selected component based on the length of the cross-section line of the selected component shape cut by the cross-section, the length of the cross-section line in the reference shape cut by the same cross-section, and the uniform elongation of the material of the metal sheet; an inflow allocation unit, allocating the calculated inflow amount to each process from the reference process to the selected process, for each cross-section; a cross-section line length calculation unit, calculating the length of the cross-section line of each cross-section in each process up to the previous process from the reference process to the selected process, based on the allocated inflow amount; and a shape determination unit, determining the shape of the metal mold in each process up to the previous process from the reference process to the selected process, based on the calculated length of the cross-section line.

[0012] According to the method of the present invention, stamped parts can be manufactured more reliably even when manufacturing stamped part shapes that cannot be formed without significant deep drawing. A stamped part shape that cannot be formed without significant deep drawing is, for example, a stamped part shape with a steeply protruding profile.

[0013] That is, according to the method of the present invention, based on the sufficient elongation of the material through multiple stamping processes, the material can be fed into the product in the exact amount required. Therefore, according to the method of the present invention, cracks and wrinkles in the product can be suppressed and the material yield can be maximized. Attached Figure Description

[0014] Figure 1 This diagram illustrates the shape determination process based on an embodiment of the present invention.

[0015] Figure 2 This is a diagram illustrating an example of a selected component shape (final component shape) based on an embodiment of the present invention.

[0016] Figure 3 It is a top view showing a setting example of lines that define multiple cross sections.

[0017] Figure 4 This is a diagram showing a configuration example of multiple cross-sections.

[0018] Figure 5 This is a diagram illustrating the relationship between the selected part shape (final part shape) and the reference shape (blank shape).

[0019] Figure 6 This is a diagram illustrating the configuration example in the embodiment. Detailed Implementation

[0020] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0021] The method for manufacturing a stamped part according to this embodiment is a method for manufacturing a stamped part by stamping a metal sheet into a final part shape through two or more stamping processes. Among them, the two or more stamping processes include a stamping process performed by deep drawing.

[0022] For example, the method for manufacturing a stamped part according to this embodiment involves stamping a metal sheet into a final part shape (target part shape) through two or more stamping processes, wherein the two or more stamping processes include a stamping process performed by deep drawing. When manufacturing this stamped part, the increase in the line length of the cross-sectional part shape in the final part shape relative to the metal sheet before forming is determined when the metal sheet is stamped into the final part shape in a single stamping process. Based on this increase in line length, the amount of material flow required to form the final part shape is determined. The determined amount of material flow is allocated to each process, and the pre-formed shape after stamping in processes other than the final stamping process is determined.

[0023] The metal molds for each process are designed to achieve the preformed shape. Furthermore, by using the designed metal molds to perform the stamping process, a product (stamped part) with the final part shape as described above is manufactured.

[0024] Next, the methods for determining the preformed shapes after stamping in each process of forming the product (stamped part) to achieve the final part shape described above, and the methods for designing metal molds in each process of achieving the determined preformed shapes will be explained.

[0025] In this embodiment, a device having such Figure 1 The metal mold shape design device with functional modules 10 to 13 shown determines the preform shape in each process and designs the metal mold in each process.

[0026] (Metal mold shape design device)

[0027] Metal mold shape design devices are provided in the form of computer-executed programs, such as... Figure 1 As shown, the system includes a profile setting unit 10 constituting the profile setting process, a required inflow calculation unit 11 constituting the required inflow calculation process, a profile component line length calculation unit 12, and a shape determination unit 13 constituting the shape determination process, and processes them in this order.

[0028] Here, one stamping process is selected from multiple stamping processes and recorded as the selected process. The shape of the part obtained through this selected process is recorded as selected part shape 1. A stamping process selected from multiple stamping processes and performed before the selected process is recorded as the reference process. The shape of the metal sheet before being stamped by this reference process is recorded as reference shape 6.

[0029] Furthermore, it is configured to include a deep-drawing stamping process in the stamping process from the reference process to the selected process.

[0030] In this embodiment, the case where the selected process is the final stamping process will be described as an example. In this case, the selected part shape 1 is the final part shape. Alternatively, in this embodiment, the case where the reference process is the initial stamping process will be described as an example. In this case, the reference shape 6 is the blank shape before stamping, such as a flat plate (see reference 6). Figure 5 ).

[0031] In this embodiment, such as Figure 2 As shown, the example described is a case where a portion of the selection component shape 1 has a protruding portion with a sharply rising cross-section. A component with a single protruding portion is, for example, a car panel component with a spoiler portion. That is, in this embodiment, the sharply rising protruding portion of the selection component shape extends in a predetermined direction (the aforementioned extending direction). Furthermore, it has a drawing region 1A, which is the area where material flows from a direction intersecting the aforementioned predetermined direction when the metal sheet is drawn into the selection component shape in a single process, and into the location of the protruding portion.

[0032] Shapes like this, with steep cross-sections, require the extension to be formed into a deep and pointed shape in the extension direction. Therefore, when forming by deep drawing, the aforementioned extension becomes a difficult part to form.

[0033] (Section Setting Section 10)

[0034] The profile setting unit 10 sets multiple profiles for cutting the selected component shape 1 in a direction along the thickness direction of the metal sheet before forming. The direction along the thickness direction is, for example, the stamping direction.

[0035] In this embodiment, the section setting unit 10 is set on a line orthogonal to the material flow direction when the metal sheet of reference shape 6 is deep-drawn into the shape of the selected component in one process. The section setting unit 10 of this embodiment assumes a plane that is orthogonal to the set line when viewed from above and extends in the direction along the thickness direction of the metal sheet before forming, and sets multiple sections cut by this plane respectively.

[0036] Here, the so-called direction of material inflow refers to the representative direction of material flow, such as the direction of material inflow exceeding a specified amount, or the general direction of material movement. Furthermore, the aforementioned "line orthogonal to the direction of inflow when viewed from above" is, for example, set at or near the location (area) where the material movement is greatest.

[0037] exist Figure 2 In the selected component shape 1 shown, as Figure 3 As shown, in a top view, material flows into the region that forms the protrusion from a direction orthogonal or substantially orthogonal to the extending direction of the protrusion relative to the drawing region 1A. In the drawing region 1A, as... Figure 3 As shown, the aforementioned line portion is designed as a straight line along the extending direction of the aforementioned protrusion when viewed from above. Furthermore, the main material flow direction is the same direction arranged along the extending direction of the aforementioned protrusion.

[0038] exist Figure 3 In the diagram, the arrow indicates the direction of material flow. Line α can also be a curve. When a protrusion extends in a curved shape, line α is also composed of a curve following that curve.

[0039] Moreover, such as Figure 4 As shown, the section setting unit 10 assumes n planes that are orthogonal to the line α set in the drawing region 1A when viewed from above and extend in the direction of the sheet thickness of the metal sheet before forming, and sets multiple sections cut by these n planes respectively. Each section is a plane that extends in the direction of the sheet thickness and is different from each other.

[0040] In this embodiment, since line α is defined as a straight line, the n planes become mutually parallel planes. That is, multiple cross-sections are planes containing line α. Therefore, as... Figure 4As shown, each section 3 is arranged along the extension direction of line α. The distance between sections 3 in a top view does not need to be set to equal intervals. For example, the positions (planes) of each section can be set so that it passes near areas with a large material inflow. Furthermore, the so-called plane containing line α refers to the plane passing through line α.

[0041] By setting multiple profiles as described above, the plane of each profile is set in the direction along the material flow direction. As a result, the amount of material flow can be appropriately distributed.

[0042] In this embodiment, the case is described in which a line α is set only for the deep drawing region 1A, which is difficult to form by deep drawing, and the pre-formed shape of the cross section in each process is determined.

[0043] In cases where there are multiple drawing regions 1A that are difficult to form through deep drawing, the processing of this embodiment can be performed on each deep drawing region 1A. Alternatively, the processing of this embodiment can be performed on multiple drawing regions 1A at once. The lines set for each drawing region 1A do not necessarily need to be continuous.

[0044] Furthermore, this embodiment can be applied even when the protrusion is not shaped to extend in a predetermined direction. For example, when the steep protrusion is circular in plan view, material flows in from the outer periphery towards the protrusion. In this case, by setting line α in a manner orthogonal to the flow, line α is, for example, set as an endless loop surrounding the protrusion.

[0045] Furthermore, in this embodiment, the term "top view" refers to the view taken from the stamping direction or the thickness direction of the metal sheet before forming.

[0046] <Example of selecting component shape 1>

[0047] Here, as described above (refer to...) Figure 2 The example of shape 1 for the selected component is an example that imitates the rear door of a car. Furthermore, it is generally difficult to form the spoiler portion into something both deep and pointed. When this shape is formed by deep drawing, the direction in which the material flows into the spoiler portion is... Figure 3 The direction shown. Therefore, the direction that is approximately perpendicular to the direction of material inflow and parallel to the z-axis is set as line α ( Figure 3 Furthermore, a group of n perpendicular planes (orthogonal to line α and extending along the plate thickness direction) is defined. Figure 4 The desired component profile shape is obtained by taking the cross-sections of the n target shapes of this planar group. n can be an integer greater than or equal to 1, but a larger number allows for a more precise estimation of the inflow rate and design of the metal mold. Therefore, 5 ≤ n is preferred.

[0048] (Required Inflow Calculation Unit 11)

[0049] The required inflow calculation unit 11 calculates the amount of material required to form the reference shape 6 into the selection component shape 1 based on the section line length of the selected component shape 1 cut by the section, the section line length of the reference shape 6 cut by the same section, and the uniform elongation of the metal plate material for each section.

[0050] The required inflow calculation unit 11 includes a line length calculation unit 11A and an inflow calculation unit 11B.

[0051] Here, in this specification, the number of multiple cross-sections is set to n, and the subscript for identifying each cross-section is set to i (1≤i≤n). For each cross-section, the line length in the selected component shape 1 cut by the same cross-section is set to L. i 1. Set the line length in the reference shape 6 to L. i 2. Set the uniform elongation of the material as El. Set the number of stamping processes from the baseline process to the selected process as m. Set the subscript for identifying the stamping process as j (1≤j≤m).

[0052] <Line Length Calculation Unit 11A>

[0053] The line length calculation unit 11A sets the cross-sectional shape of each component of the cut selection component shape 1 to S in each set cross-section. i (Here, 1≤i≤n). Furthermore, the line lengths (L) in selected component shape 1 on the same cross-section are calculated separately. i 1) and the line length (L) in the reference shape 6 i 2). That is, such as Figure 5 As shown, in each cross-section, the line length (L) in selected component shape 1 is calculated. i 1) and the line length (L) in the reference shape 6 (planar shape in this embodiment) when the cross-section is projected onto the stamping direction. i 2).

[0054] <Inflow Calculation Unit 11B>

[0055] The inflow calculation unit 11B calculates the inflow rate based on the uniform elongation (E1) of the metal sheet material and the line length (L) in the selected component shape 1 calculated by the line length calculation process. i 1) and the line length (L) in reference shape 6 i 2) Calculate the required inflow amount (L) for forming the selected component shape 1 in each section for each cross-section. i 3).

[0056] In this embodiment, the required inflow amount (L) for molding is calculated according to equation (1). i 3).

[0057] L i 3 = L i 1-L i 2-aEl……(1)

[0058] Where 0 < a < 1.

[0059] Here, L i 1 is the section line length of the i-th section in the selected component shape 1 (the final component shape in this embodiment). L i 2 is the section line length of the i-th section in the reference shape 6 (initial state in this embodiment). Therefore, in order to change the section line length from the initial state to the final state, the line length needs to be lengthened (increased) (L). i 1-L i 2) The amount of length. This elongation needs to be determined by the amount of material elongation (aEl) and the inflow rate (L). i 3) The sum of these can be used to make up for the shortfall.

[0060] The amount of material elongation is limited by the material’s uniform elongation (E1), so an inflow is required that cannot compensate for the loss.

[0061] The constant that determines the extent to which the material is stretched relative to its uniform elongation rate is the coefficient 'a' in equation (1). When a = 0, it means the material does not stretch at all, and any shortfall in length is compensated entirely by the inflow. When a = 1, it means the material stretches to its limit throughout the entire design area, and any remaining shortfall is compensated by the inflow. Theoretically, a can take any real number greater than 0 and less than 1. However, assuming a = 0, the material does not stretch at all, and there is no point in using the method of this invention. Furthermore, when a = 1, it is necessary to stretch to the limit throughout the entire design area, but such forming is very difficult using conventional stamping. Therefore, 0 and 1 are removed from the range of a. A preferred range of a is 0.2 ≤ a ≤ 0.8.

[0062] (Sectional component line length calculation unit 12)

[0063] The section component line length calculation unit 12 allocates the calculated inflow amount to each process from the reference process to the selected process for each section. Furthermore, based on the allocated inflow amount, it calculates the section line length in each process up to the previous process from the reference process to the selected process.

[0064] The profile component line length calculation unit 12 includes an inflow distribution unit 12A constituting the inflow distribution process and a profile line length calculation unit 12B constituting the profile line length calculation process.

[0065] <Inflow Distribution Section 12A>

[0066] The inflow allocation unit 12A performs the process of allocating the calculated inflow to each process from the baseline process to the selected process according to each profile.

[0067] The inflow L obtained by the required inflow calculation unit 11 i 3 can be calculated as the sum of the inflows from the baseline process to the selected process. Therefore, it is possible to allocate the inflows to each process.

[0068] In the inflow distribution unit 12A, the inflow of the k-th process in the i-th profile is used as b for each profile. k ·L i 3. Distribute the allocation.

[0069] Here, k is the process number. The baseline process is k=1, and the selected process is k=m. Additionally, i is the section number. Based on coefficient b... k Let be the degree to which the material flows in during the k-th process out of all m stamping processes.

[0070] Additionally, due to Σ k＝1 m (b k ·L i 3) = L i 3, therefore, it is set to satisfy Σ. k＝1 m (b k ) = 1. Additionally, set 0 ≤ b k ≤1.

[0071] For example, in the case of molding through two processes (m=2), the inflow rate of the first process is set to b1×L. i 3. Set the inflow rate of the second process to b2×L i 3. Where b1 + b2 = 1. In this case, when b1 = 0, it means that no material flows in during the first process. Similarly, when b2 = 0, it means that no material flows in during the second process.

[0072] Generally, in the final stamping process, considering factors such as appearance and part shape accuracy, it is preferable to suppress flow and apply tension to the part. Therefore, b is preferred. m <1. On the other hand, in the previous molding process, b was reduced to the extent possible. m Therefore, b is preferred. k >0 (k<m).

[0073] <Section Line Length Calculation Section 12B>

[0074] Based on the allocated inflow, the profile length calculation unit 12B calculates the profile length of each profile in each process from the reference process to the previous process of the selected process.

[0075] In each section, the section line length (L) of each process i 4) is the sum of the material that flowed in before this process and the length of the line in the initial state. Therefore, it is expressed by equation (2).

[0076] The section line length calculation unit 12B calculates the section line length (L) in the j-th process in each section using formula (2). i 4). Furthermore, j takes the value 1≤j≤m-1. Since the section line length in the j-th process is the section of part shape 1, it does not need to be calculated.

[0077] L i 4 = L i 2+(b1+…+b j )·L i 3

[0078] =L i 2+Σ k＝1 j (b k ·L i 3)……(2)

[0079] (Shape Determination Section 13)

[0080] The shape determination unit 13 determines the preformed shape after stamping in each process from the reference process to the process preceding the selected process based on the calculated section line length. Furthermore, it determines the shape of the metal mold that will become the determined preformed shape.

[0081] The shape determination unit 13 in this embodiment includes an adjustment unit 13A and a shape setting unit 13B that constitute the adjustment process. The adjustment unit 13A may also be omitted.

[0082] <Adjustment Section 13A>

[0083] The adjustment unit 13A adjusts the length of the section line of each section without changing the sum of the section line lengths of each section calculated by the section line length calculation unit 12B. This adjustment is performed for each process from the reference process to the process preceding the selected process. The adjustment unit 13A adjusts the section line length, for example, based on the difference in section line lengths between adjacent sections observed from the stamping direction. For example, it adjusts the length in a way that minimizes the difference in line lengths between adjacent sections.

[0084] In this embodiment, the adjustment unit 13A is based on the section length L14 to L14 in the process that is being targeted.n The section lengths L14 to L are adjusted by maintaining the condition that the total sum of 4 remains constant. n The distribution of 4 is used to calculate the adjusted profile lengths L15 to L. n 5.

[0085] Here, the section line length calculation unit 12B calculates the section line length L of each section of the preform shape specified in each stamping process. i 4. Among these profile lengths, there exists a profile length L relative to the preceding process in a certain process. (i－1) 4 and the section length L in the next process (i+1) 4. The length L of the cross-section line in a certain process. i 4. Extremely long or extremely short cross-sections. In this case, it means that the shape of the part changes drastically at that location. In this case, during molding, there is a possibility that strain or excess material may be extremely concentrated at that location, resulting in cracks or wrinkles. To prevent this from happening, in the adjustment section 13A of this embodiment, the difference in cross-sectional line length between adjacent processes, i.e., L... i 4 and L (i－1) 4 and L (i+1) The decreasing line length difference in step 4 causes a change in the circumferential line length distribution. The section line length L can then be calculated. i 5.

[0086] Specifically, L is determined in a manner that satisfies equations (3) and (4) below. i 5.

[0087] L i 5≤c·(L (i－1) 4+L (i+1) 4) / 2……(3)

[0088] Where 0.75≤c≤1.25.

[0089] L15+…+L i 5+…L n 5 = L14 + ... + L i 4+…L n 4……(4)

[0090] The upper and lower limits of the difference between the line length of the adjacent section and the line length of the adjacent section are defined by c in equation (3). The range of c is 0.75≤c≤1.25, preferably 0.85≤c≤1.15.

[0091] In addition, L i 5. It needs to satisfy equation (4). That is, it is defined as all L i The sum of 4 and all L i The sum of 5 is equal.

[0092] The larger the number of profiles *n*, the closer the sum of the profile lengths is to the surface area. From this perspective, it is better to take a larger value for *n*. That is, it is defined as all L... i The sum of 4 and all L i The sum of 5 is equivalent to changing the cross-sectional shape without changing the surface area. By partially adjusting the line length without changing the surface area, it is possible to suppress localized material elongation without altering the overall material elongation.

[0093] If the conditions of equation (4) are not met after processing up to equation (3), perform the following operation (5) to adjust L. i 5 satisfies equation (4).

[0094] L i 5≤d·(L (i－1) 5+L (i+1) 5) / 2……(5)

[0095] Where 0.75≤d≤1.25.

[0096] The preferred range for d is 0.85 ≤ d ≤ 1.15.

[0097] <Shape Setting Section 13B>

[0098] The shape setting unit 13B uses the section line length L obtained after all the above processing. i 5. To design the preform shape for the (m-1) process. The (m-1) process is the process from the baseline process to the process preceding the selected process.

[0099] The design of each process, by combining the cross-section at the i-th position, has L. i The line length is 5, and the continuous curved surface is smoothly connected to the adjacent (i-1)th and (i+1)th cross-sections. The design shape preferably satisfies the conditions (1) to (4).

[0100] (1) Smoothly connect with shapes outside the design area.

[0101] (2) The cross-section is a smooth curve and does not have any outliers.

[0102] (3) The metal mold is not disturbed when it is assembled into the metal mold for the next process.

[0103] (4) In one process, the blank does not come into contact with the die before holding it.

[0104] Furthermore, the shape of the metal mold corresponding to the preformed shape of the designed and derived shape.

[0105] Here, if the required material inflow cannot be smoothly allocated within the current number of stamping processes, the above process can be repeated by increasing the number of stamping processes. Alternatively, if there is a surplus exceeding a specified amount in the allocation of inflow in each process, the number of processes can be reduced to perform the design of the preformed shape (metal mold shape) in each process. The number of processes can also be optimized based on the final part shape using the processing of this embodiment.

[0106] (Metal mold)

[0107] Examples of metal molds designed by the metal mold shape design apparatus of this embodiment and used in each process will be described.

[0108] The metal molds described below are those used in each process from the baseline process to the selected process described above. The forming surfaces of each metal mold are as follows.

[0109] The forming surface of the metal mold for the selection process is modeled after the shape of the selected component.

[0110] Here, when a metal mold for a selection process is used to draw a metal sheet of a reference shape into the shape of a selection part in one process, a line orthogonal to the direction of material flow when viewed from above is set, and multiple cross-sections are set, each cut by a plane that is orthogonal to the aforementioned line when viewed from above and extends along the thickness direction of the metal sheet before forming.

[0111] In addition, for each section arranged along the extension direction on the set line, the material inflow amount in the forming surface of the metal mold of each process is set according to the section line length of the selected component shape cut by the section, the section line length in the reference shape cut by the same section as the section, and the uniform elongation of the metal sheet material.

[0112] Additionally, the number of cross-sections is set to n, the index of each cross-section is set to i (1≤i≤n), and for each cross-section, the line length in the selected component shape cut by the same cross-section is set to L. i 1. Set the line length in the above-mentioned reference shape as L. i 2. Set the uniform elongation of the material as El, set the number of stamping processes from the reference process to the selected process as m, and set the subscript for identifying the stamping process as j (1≤j≤m).

[0113] In this case, for the inflow rate of the material set above, the inflow rate (L) in section i is set by the following formula (1). i 3).

[0114] Furthermore, the section line length (L) of section i in the forming surface of the metal mold used in the j-th process can be expressed by the following equation (2). i 4).

[0115] In addition, coefficient b k (1≤k≤m) satisfies Σ j＝1 m (b k ) = 1.

[0116] L i 3 = L i 1-L i 2-a·El……(1)

[0117] Where 0 < a < 1,

[0118] L i 4 = L i 2+Σ k＝1 j (b k ·L i 3)……(2)

[0119] Where, 0≤b k ≤1.

[0120] Here, the selected process is the final stamping process, while the aforementioned reference process is the initial stamping process.

[0121] Additionally, the selected component shape is suitable for the protrusion to extend in a predetermined direction and has a drawn region, wherein the drawn region is the area where material flows from a direction intersecting the predetermined direction when the metal sheet is drawn into the selected component shape in a single process toward the location of the protrusion. In this case, the portion of the line passing through the drawn region can also be set as a line along the predetermined direction.

[0122] In addition, it is preferable that the difference in section line length between adjacent sections in the forming surface of the metal mold in each of the above processes is below a preset value.

[0123] For example, based on the section line lengths L14 to L in the forming surface during the process that does not change the object. n The sum of 4 is used to adjust the section length L14~L n The distribution of 4, and the adjusted profile length L15~L n 5.

[0124] Here, the section line length L of each section that defines the shape of the forming surface in each stamping process is calculated. i4. Among these profile lengths, there exists a profile length L that corresponds to the preceding process in a given process. (i－1) 4 and the section length L in the next process (i+1) 4. The length L of the cross-section line in a certain process. i 4. Extremely long or short cross-sections. This means that the part shape changes drastically at that location. In this case, during molding, there is an extreme concentration of strain or excess material at that point, potentially leading to cracks or wrinkles. To prevent this, the difference in cross-section length between adjacent processes, i.e., L... i 4 and L (i－1) 4 and L (i+1) The decreasing line length difference in step 4 causes a change in the circumferential line length distribution. The section line length L can then be calculated. i 5.

[0125] Specifically, L is determined in a manner that satisfies equations (3) and (4) below. i 5.

[0126] L i 5≤c·(L (i－1) 4+L (i+1) 4) / 2……(3)

[0127] Where 0.75≤c≤1.25.

[0128] L15+…+L i 5+…L n 5 = L14 + ... + L i 4+…L n 4……(4)

[0129] The upper and lower limits of the difference between the line length of the adjacent section and the line length of the adjacent section are defined by c in equation (3). The range of c is 0.75≤c≤1.25, preferably 0.85≤c≤1.15.

[0130] In addition, L i 5. It needs to satisfy equation (4). That is, it is defined as all L i 4 and all L i The sum of 5 is equal.

[0131] The larger the number of profiles *n*, the closer the sum of the profile lengths is to the surface area. From this perspective, it is better to take a larger value for *n*. That is, it is defined as all L... i The sum of 4 and all L i The sum of 5 is equivalent to changing the cross-sectional shape without changing the surface area. By partially adjusting the line length without changing the surface area, it is possible to suppress localized material elongation without altering the overall material elongation.

[0132] If the conditions of equation (4) are not met after processing up to equation (3), perform the following operation (5) to adjust L. i 5 satisfies equation (4).

[0133] L i 5≤d·(L (i－1) 5+L (i+1) 5) / 2……(5)

[0134] Where 0.75≤d≤1.25.

[0135] The preferred range for d is 0.85 ≤ d ≤ 1.15.

[0136] (Other actions)

[0137] In this embodiment, a metal sheet is stamped into a final part shape through two or more stamping processes, including a stamping process performed by deep drawing. When manufacturing this stamped part, the inflow amount in each process of each cross section is set to an appropriate value to set each pre-formed shape (metal mold shape) in each process.

[0138] Therefore, even when manufacturing stamped parts that cannot be formed without significant deep drawing, the material flow rate obtained in each stamping process can be appropriately set. As a result, the generation of cracks and wrinkles can be suppressed in the manufactured stamped parts.

[0139] Furthermore, the buffer pressure during stamping and the weld shape of the metal mold are adjusted, and the inflow rate at each point is made to approximate the section length L. i The value of 3 is adjusted accordingly. As a result, the inflow of material is minimized, improving the yield.

[0140] That is, in this embodiment, for example, when deep drawing is performed through multiple processes, multiple cross-sections almost parallel to the stamping direction are set based on the part shape obtained through the final stamping process and the initial state of the blank. Furthermore, the final required section line length and the initial section shape are calculated based on these cross-sections. Based on the calculation results and the uniform elongation of the material used, the required flow rate for forming is calculated. The calculated flow rate is allocated to each process, and the section line length in each process is calculated. Moreover, based on the calculated section line length, the metal die shape (pre-formed shape) for each process (without the final stamping process) is designed. By using the designed metal die to perform stamping in each process, stamped parts (stamped parts with the final part shape) without cracks or wrinkles can be obtained, maximizing the yield.

[0141] Here, during deep drawing, if the material inflow is too small, cracks will occur due to insufficient material in the stamped part causing the material to elongate beyond its limit. Conversely, if the material inflow is too large, cracks are less likely to occur because there is sufficient material in the stamped part. However, if too much material is added, wrinkles are a concern. Furthermore, this is disadvantageous from the perspective of material yield, so it is important to optimize the inflow rate.

[0142] Furthermore, in deep drawing, when forming using conventional methods, the strain of the material introduced to the bottom of the punch is relatively small due to frictional resistance, bending resistance in the punch shoulder, etc. Therefore, the strain increases in the punch shoulder, die shoulder, or the wall between them, leading to a higher likelihood of cracking at these locations. Thus, even though the introduced strain is relatively small, there is a concern that the entire stamped part may crack due to localized strain concentration. In other words, it is difficult to say that the material's elongation is being fully utilized in most cases.

[0143] In contrast, in this embodiment, the required flow rate when forming the target shape through deep drawing can be estimated precisely. Furthermore, in this embodiment, the flow rate is divided and flowed in stages in each step, and the shape is formed with an appropriate cross-sectional length. As a result, by pre-introducing strain near the bottom of the punch, where strain is difficult to penetrate in conventional forming, improved formability and yield can also be achieved.

[0144] (other)

[0145] This disclosure may also take the following structure.

[0146] (1) The structure is as follows: It is a method for manufacturing a stamped part in which a metal sheet is stamped into a final part shape through multiple stamping processes. One of the multiple stamping processes is selected as the selected process, and the part shape obtained in the selected process is designated as the selected part shape 1. A stamping process selected from the multiple stamping processes and performed before the selected process is designated as a reference process, and the shape of the metal sheet before stamping in the reference process is designated as the reference shape 6. The stamping process from the reference process to the selected process includes a deep-drawing stamping process. The method for manufacturing this stamped part comprises: a profile setting process, in which a line is set orthogonal to the direction of material flow when the metal sheet of the reference shape is deep-drawn into the selected part shape in one process, and directions orthogonal to the line in the view and along the thickness direction of the metal sheet before forming are set. The process includes: a plurality of cross-sections cut by an upwardly extending plane; an inflow calculation step, which, for each cross-section, calculates the amount of material required to form the reference shape 6 into the selected component shape 1 based on the cross-section length of the selected component shape 1 cut by the cross-section, the cross-section length of the reference shape 6 cut by the same cross-section, and the uniform elongation of the material of the metal sheet; an inflow allocation step, which, for each cross-section, allocates the calculated inflow amount to each process from the reference process to the selected process; a cross-section length calculation step, which, based on the allocated inflow amount, calculates the cross-section length of each cross-section in each process up to the previous process from the reference process to the selected process; and a shape determination step, which, based on the calculated cross-section length, determines the preformed shape after stamping in each process up to the previous process from the reference process to the selected process.

[0147] At this point, the selected process is the final stamping process, and the reference process is the initial stamping process.

[0148] Based on this structure, a method for manufacturing stamped parts can be provided that can be applied even when manufacturing stamped parts that cannot be formed without significant deep drawing.

[0149] (2) The protrusion of the above-mentioned selection component shape extends in a predetermined direction, and the above-mentioned selection component shape has a deep drawing region 1A. The deep drawing region 1A is the area in which material flows from a direction that intersects the predetermined direction when viewed from above towards the position of the protrusion when the metal sheet is deep drawn into the shape of the above-mentioned selection component in a process. The above-mentioned profile setting process sets the line portion of the above-mentioned line that passes through the deep drawing region 1A as a line along the predetermined direction.

[0150] According to this structure, a method for manufacturing stamped parts can be provided that can be applied even when manufacturing stamped parts with one or more drawing regions 1A that cannot be formed without significant drawing.

[0151] (3) The shape determination process has an adjustment process, wherein in the adjustment process, in each process from the reference process to the previous process of the selection process, the length of the section line length of each section is adjusted without changing the sum of the section line lengths of each section calculated by the section line length calculation process. The shape determination process determines the preformed shape after stamping based on the section line length of each section after adjustment by the adjustment process.

[0152] For example, in the above adjustment process, the section line length is adjusted based on the difference in section line length between adjacent sections.

[0153] According to this structure, even when manufacturing stamped parts that cannot be formed without significant deep drawing, the amount of material flowing in each stamping process can be set more appropriately.

[0154] Here, when selecting part shape 1 and forming it through a single stamping process, in the case of a protruding portion with a steep cross-section extending in a specified direction, multiple cross-sections defined by line α are arranged in the aforementioned extending direction. Moreover, the position of each cross-section can be easily set along the main flow direction of the material, allowing for a more appropriate distribution of the material flow.

[0155] Furthermore, by forming multiple cross-sections based on line α, the multiple cross-sections are arranged along line α when viewed from above, thus making it easy and reliable to adjust the line length between the cross-sections in the adjustment unit 13A.

[0156] (4) With the number of multiple cross-sections set to n, and the index of each cross-section set to i (1≤i≤n), for each cross-section, the line length of the selected component shape 1 cut by the same cross-section is set to L. i 1. Set the line length in the above-mentioned reference shape 6 as L. i 2. With the uniform elongation of the material set as El, the number of stamping processes from the above-mentioned reference process to the above-mentioned selected process set as m, and the subscript identifying the stamping process set as j (1≤j≤m), the inflow amount (L) in the section i calculated by the above-mentioned inflow amount calculation process is obtained by the following formula (1). i 3) The length of section i in the j-th process calculated by the above section length calculation process is obtained by formula (2) below. i4) Based on the coefficient 'a' in equation (1), determine the degree to which the material will be stretched relative to its uniform elongation, and based on the coefficient 'b' in equation (2). k Let be the coefficient b, which sets the degree to which material flows in during the j-th process within all m stamping processes. k (1≤k≤m) is set to satisfy Σ j＝1 m (b k ) = 1.

[0157] L i 3 = L i 1-L i 2-a·El……(1)

[0158] Where 0 < a < 1,

[0159] L i 4 = L i 2+Σ k＝1 j (b k ·L i 3)……(2)

[0160] Where, 0≤b k ≤1.

[0161] Based on this structure, the appropriate profile length in each process can be set more reliably.

[0162] (5) is a metal die design method used when a metal sheet is stamped into a final part shape through two or more stamping processes including a stamping process performed by deep drawing. Based on the increase in the cross-sectional length of the final part shape relative to the shape before stamping when the metal sheet is stamped into the final part shape in one stamping process, the amount of material flow required to form the final part shape is calculated, and the calculated amount of material flow is allocated to each process including the final stamping process. Based on the allocated amount of material flow, the shape of the metal die used in processes other than the final stamping process is determined.

[0163] For example, in a metal mold design method used to stamp a metal sheet into a final part shape through multiple stamping processes, one of the multiple stamping processes is selected as the selected process, and the part shape obtained through the selected process is designated as the selected part shape 1. A stamping process selected from the multiple stamping processes and performed before the selected process is designated as the reference process, and the shape of the metal sheet before stamping through the reference process is designated as the reference shape 6. In this case, the stamping process from the reference process to the selected process includes a deep-drawing process. The metal mold design method includes: a profile setting process, which sets a line orthogonal to the direction of material flow when the metal sheet of the reference shape is deep-drawn into the selected part shape through one process, and sets directions orthogonal to the line in the view and along the thickness direction of the metal sheet before forming. The process includes: a plurality of cross-sections cut by an upwardly extending plane; an inflow calculation step, which, for each cross-section, calculates the amount of material required to form the reference shape 6 into the selected component shape 1 based on the cross-section length of the selected component shape 1 cut by the cross-section, the cross-section length of the reference shape 6 cut by the same cross-section, and the uniform elongation of the material of the metal plate; an inflow allocation step, which allocates the calculated inflow amount to each step from the reference step to the selected step, based on each cross-section; a cross-section length calculation step, which calculates the cross-section length of each cross-section in each step from the reference step to the previous step of the selected step, based on the allocated inflow amount; and a shape determination step, which determines the shape of the metal mold used in each step from the reference step to the previous step of the selected step, based on the calculated cross-section length.

[0164] The selected process is the final stamping process, and the reference process is the initial stamping process.

[0165] Based on this structure, it is possible to design metal mold shapes for each process that can be applied even when manufacturing stamped parts that cannot be formed without significant deep drawing.

[0166] (6) The shape determination process has an adjustment process, wherein in the adjustment process, in each process from the reference process to the previous process of the selection process, the length of the section line length of each section is adjusted without changing the sum of the section line lengths of each section calculated by the section line length calculation process. The shape determination process determines the preformed shape after stamping based on the section line length of each section after adjustment by the adjustment process.

[0167] In the above adjustment process, for example, the section line length is adjusted based on the difference in section line length between adjacent sections.

[0168] Based on this structure, it is possible to design metal dies that can appropriately set the material inflow in each stamping process, even when manufacturing stamped parts that cannot be formed without significant deep drawing.

[0169] (7) With the number of multiple cross-sections set to n, and the index of each cross-section identified set to i (1≤i≤n), for each cross-section, the line length of the selected component shape 1 cut by the same cross-section is set to L. i 1. Set the line length in the above-mentioned reference shape 6 as L. i 2. With the uniform elongation of the material set as El, the number of stamping processes from the above-mentioned reference process to the above-mentioned selected process set as m, and the subscript identifying the stamping process set as j (1≤j≤m), the inflow amount (L) in the section i calculated by the above-mentioned inflow amount calculation process is obtained by the following formula (1). i 3) The length of section i in the j-th process calculated by the above section length calculation process is obtained by formula (2) below. i 4) Based on the coefficient 'a' in equation (1), determine the degree to which the material will be stretched relative to its uniform elongation, and based on the coefficient 'b' in equation (2). k Let be the coefficient b, which sets the degree to which material flows in during the j-th process within all m stamping processes. k (1≤k≤m) constitutes a condition that satisfies Σ j＝1 m (b k ) = 1.

[0170] L i 3 = L i 1-L i 2-a·El……(1)

[0171] Where 0 < a < 1,

[0172] L i 4 = L i 2+Σ k＝1 j (b k ·L i 3)……(2)

[0173] Where, 0≤b k ≤1.

[0174] Based on this structure, it is possible to design metal mold shapes that can more reliably set the appropriate section line lengths for each process.

[0175] (8) A method for manufacturing a stamping part using a metal mold designed by the above-described metal mold design method.

[0176] Based on this structure, a method for manufacturing stamped parts can be provided that can be applied even when manufacturing stamped parts that cannot be formed without significant deep drawing.

[0177] (9) is a metal mold shape design device for determining the shape of the metal mold used in each process other than the final stamping process when a metal sheet is stamped into the final part shape through multiple stamping processes. When selecting one process from the multiple stamping processes as the selection process, and taking the part shape obtained through the selection process as the selection part shape 1, and selecting a stamping process performed before the selection process as the reference process, and taking the shape of the metal sheet before stamping through the reference process as the reference shape 6, the stamping process from the reference process to the selection process includes a stamping process with deep drawing. The metal mold shape design device includes: a profile setting unit 10, which sets a line orthogonal to the direction of material flow when the metal sheet of the reference shape is deep drawn into the selection part shape through one process in plan view, and sets lines orthogonal to the lines in plan view and along the forming... The metal plate is cut into multiple cross-sections by a plane extending in the thickness direction; the inflow calculation unit 11B calculates the amount of material required to form the reference shape 6 into the selection component shape 1 based on the cross-section length of the selected component shape 1 cut by the cross-section, the cross-section length of the reference shape 6 cut by the same cross-section, and the uniform elongation of the metal plate material for each cross-section; the inflow allocation unit 12A allocates the calculated inflow amount to each process from the reference process to the selection process for each cross-section; the cross-section length calculation unit 12B calculates the cross-section length of each cross-section in each process up to the previous process from the reference process to the selection process based on the allocated inflow amount; and the shape determination unit 13 determines the metal mold shape in each process up to the previous process from the reference process to the selection process based on the calculated cross-section length.

[0178] The selected process can be set as the final stamping process, and the reference process can be set as the initial stamping process.

[0179] Based on this structure, it is possible to design metal mold shapes for each process that can be applied even when manufacturing stamped parts that cannot be formed without significant deep drawing.

[0180] (10) The shape determination unit 13 has an adjustment unit 13A, which adjusts the length of the section line of each section in each process from the reference process to the previous process of the selection process without changing the sum of the section line lengths of each section calculated by the section line length calculation unit 12B. The shape determination unit 13 determines the shape of the metal mold based on the section line length of each section adjusted by the adjustment unit 13A.

[0181] For example, in the adjustment section 13A described above, the section line length is adjusted based on the difference in section line length between adjacent sections.

[0182] The aforementioned selection component shape 1 is preferably a shape in which, when formed by a single stamping process, material flows from multiple directions around the outer periphery of the plate toward the center when viewed from above. For example, the aforementioned selection component shape 1 is a shape having a top plate portion and a side wall portion that is continuous around the entire circumference of the top plate portion and is an endless ring shape when viewed from above.

[0183] Based on this structure, it is possible to design metal dies that can appropriately set the material inflow in each stamping process, even when manufacturing stamped parts that cannot be formed without significant deep drawing.

[0184] (11) The structure is as follows: the number of multiple cross-sections is set to n, the index of each cross-section is set to i (1≤i≤n), and for each cross-section, the line length of the selected component shape 1 cut by the same cross-section is set to L. i 1. Set the line length in the above-mentioned reference shape 6 as L. i 2. With the uniform elongation of the material set as El, the number of stamping processes from the above-mentioned reference process to the above-mentioned selection process set as m, and the subscript for identifying the stamping process set as j (1≤j≤m), the inflow amount (L) in section i calculated by the inflow amount calculation unit 11B is obtained by the following formula (1). i 3) The section length (L) of section i in the j-th process calculated by the section length calculation unit 12B above is obtained by formula (2) below. i 4) Based on the coefficient 'a' in equation (1), determine the degree to which the material will be stretched relative to its uniform elongation, and based on the coefficient 'b' in equation (2). k Let be the coefficient b, which sets the degree to which material flows in during the j-th process within all m stamping processes. k (1≤k≤m) satisfies Σ j＝1 m (b k ) = 1.

[0185] L i 3 = L i 1-Li 2-a·El……(1)

[0186] Where 0 < a < 1,

[0187] L i 4 = L i 2+Σ k＝1 j (b k ·L i 3)……(2)

[0188] Where, 0≤b k ≤1.

[0189] Based on this structure, it is possible to design metal mold shapes that can more reliably set the appropriate section line lengths for each process.

[0190] (12) refers to the various metal dies used in each process of manufacturing stamped parts by stamping metal sheets into the final part shape through multiple stamping processes.

[0191] From the plurality of stamping processes described above, one process is selected as the selected process, and the part shape obtained in the selected process is taken as the selected part shape. A stamping process selected from the plurality of stamping processes and performed before the selected process is taken as the reference process, and the shape of the metal sheet before stamping in the reference process is taken as the reference shape. Furthermore, the stamping process from the reference process to the selected process includes a stamping process involving deep drawing.

[0192] For the forming surface of each metal mold used in each process from the aforementioned standard process to the aforementioned selected process,

[0193] The forming surface of the metal mold in the above selection process is modeled after the shape of the selected component.

[0194] A line is set that is orthogonal to the direction of material flow when the metal mold of the above-mentioned selection process is used to draw the metal sheet of the above-mentioned reference shape into the shape of the above-mentioned selection component in one process, and multiple cross-sections are set that are respectively cut by a plane that is orthogonal to the line in the view and extends along the thickness direction of the metal sheet before forming.

[0195] For each of the aforementioned cross-sections arranged along the extension direction on the set lines, the material inflow amount in the forming surface of the metal mold of each process is set according to the length of the cross-section line of the selected component shape cut by the cross-section, the length of the cross-section line in the reference shape cut by the same cross-section, and the uniform elongation of the material of the metal sheet.

[0196] Let n be the number of the aforementioned cross-sections, and i be the index of each cross-section (1≤i≤n). For each cross-section, let L be the line length of the selected component shape cut by the same cross-section. i 1. Set the line length in the above-mentioned reference shape as L. i 2. Given that the uniform elongation of the material is E1, the number of stamping processes from the above-mentioned baseline process to the above-mentioned selected process is m, and the subscript identifying the stamping process is j (1≤j≤m),

[0197] For the material inflow rate set above, the inflow rate (L) in section i is set by the following formula (1). i 3),

[0198] The length of the section line (L) of section i in the forming surface of the metal mold used in the j-th process is expressed by the following equation (2). i 4),

[0199] coefficient b k (1≤k≤m) satisfies Σ j＝1 m (b k ) = 1,

[0200] L i 3 = L i 1-L i 2-a·El……(1)

[0201] Where 0 < a < 1,

[0202] L i 4 = L i 2+Σ k＝1 j (b k ·L i 3)……(2)

[0203] Where, 0≤b k ≤1.

[0204] (13) The above-mentioned selected process is the final stamping process, and the above-mentioned reference process is the initial stamping process.

[0205] (14) The protrusion of the above-mentioned selection component shape extends in a predetermined direction, and the above-mentioned selection component shape has a drawing region, which is the area in which material flows from a direction intersecting the predetermined direction in a top view toward the position of the protrusion when the metal sheet is drawn into the shape of the above-mentioned selection component in one process.

[0206] The portion of the line that passes through the deep drawing region is set to be a line along the specified direction.

[0207] (15) In the forming surface of the metal mold in each of the above processes, the difference in the length of the section line between adjacent sections is below a preset value.

[0208] Example

[0209] The blank made of metal sheet is stamped into shape as follows Figure 2 The case of manufacturing stamped parts based on the final part shape shown was studied.

[0210] In Example 1 based on this embodiment, under the conditions of n=20 cross-sections, m=2 stamping processes, coefficient a=0.5, and coefficient b=0.9, the preform shape for the first stamping process was designed. This preform shape is shown below. Figure 6 (a). Furthermore, Figure 6 (b) indicates the final part shape. In this embodiment 1, the adjustment process (adjustment part 13A) is omitted. In this example, the first stamping process (initial stamping process) involves deep drawing.

[0211] Furthermore, as a metal sheet, GA steel sheet (alloyed hot-dip galvanized steel sheet) with a tensile strength of 270 MPa is used, and the thickness is 0.65 mmt.

[0212] By using the pre-formed metal mold shape described above and stamping the metal sheet through two stamping processes to form the final part shape, a product without cracks or wrinkles and with good quality can be obtained.

[0213] On the other hand, when the blank is stamped into the final part shape through a single stamping process, a large crack is generated in a part of the deep drawing region 1A, which does not meet the performance requirements of the product.

[0214] In summary, it has been found that by designing the pre-formed shapes (metal mold shapes) in each process based on the present invention, it is possible to obtain good products without cracks or wrinkles.

[0215] The contents of Japanese Patent Application 2020-147655 (filed September 2, 2020), which claims priority in this application, are incorporated herein by reference. A limited number of embodiments have been described herein, but the scope of the claims is not limited to these embodiments, and modifications based on the embodiments disclosed above will be apparent to those skilled in the art.

[0216] Explanation of reference numerals in the attached figures

[0217] 1…Select component shape; 1A…Drawing area; 6…Reference shape; 10…Section setting unit; 11…Required inflow calculation unit; 11A…Line length calculation unit; 11B…Inflow calculation unit; 12…Section component line length calculation unit; 12A…Inflow allocation unit; 12B…Section line length calculation unit; 13…Shape determination unit; 13A…Adjustment unit; 13B…Shape setting unit; α…Line.

Claims

1. A method of manufacturing a press part, characterized by comprising: a plurality of press processes for press-forming a metal sheet into a final part shape, selecting one of the plurality of press processes as a selected process and a part shape obtained in the selected process as a selected part shape, selecting one of the plurality of press processes performed before the selected process as a reference process and a shape of the metal sheet before press-forming in the reference process as a reference shape, in the press processes from the reference process to the selected process, including a press process having a draw-forming, the method of manufacturing the press part comprising: a cross section setting process of setting a line orthogonal to a direction of material flow when a metal sheet of the reference shape is draw-formed into the selected part shape by one process in plan view, and setting a plurality of cross sections each cut by a plane orthogonal to the line in plan view and extending in a direction along a sheet thickness direction of the metal sheet before forming; a flow amount calculation process of calculating, for each cross section, a flow amount of material required to form the reference shape into the selected part shape based on a cross section line length of the selected part shape cut by the cross section, a cross section line length in the reference shape cut by the same cross section as the cross section, and a uniform elongation of the material of the metal sheet; a flow amount distribution process of distributing, for each cross section, the calculated flow amount to each of the processes from the reference process to the selected process; a cross section line length calculation process of calculating, for each cross section, a cross section line length in each of the processes from the reference process to the process before the selected process based on the distributed flow amount; a shape determination process of determining, based on the calculated cross section line lengths, a pre-form shape after press-forming in each of the processes from the reference process to the process before the selected process.

2. The method of manufacturing the press part according to claim 1, characterized in that: the selected process is a final press process, and the reference process is an initial press process.

3. The method of manufacturing the press part according to claim 1 or 2, characterized in that: the selected part shape has a protruding portion extending toward a prescribed direction, and has a draw region in which material flows from a direction intersecting the prescribed direction in plan view toward a position becoming the protruding portion when the metal sheet is draw-formed into the selected part shape by one process, in the cross section setting process, a line portion of the set line passing through the draw region is set as a line along the prescribed direction.

4. The method of manufacturing the press part according to claim 1 or 2, characterized in that: the shape determination process has an adjustment process of adjusting, in each of the processes from the reference process to the process before the selected process, a length of the cross section line length of each cross section without changing a total of the cross section line lengths of each cross section calculated by the cross section line length calculation process. The shape determining step determines the pre-molded shape after the press forming based on the cross-sectional line length of each cross section adjusted by the adjusting step.

5. The method of manufacturing a press part according to claim 4, characterized in that, In the adjusting step, the cross-sectional line length is adjusted based on the difference between the cross-sectional line lengths of adjacent cross sections.

6. The method of manufacturing a press part according to claim 1 or 2, characterized in that, In the case where the number of the plurality of sections is set to n, the index for identifying each section is set to i, and the line length in the above selected component shape cut by the same section is set to L for each section i 1, the line length in the above reference shape is set to L i 2, the uniform elongation of the material is set to El, the number of the press processes from the above reference process to the above selected process is set to m, and the index for identifying the press process is set to j, where 1≤i≤n and 1≤j≤m, The inflow amount L in the profile i calculated in the above inflow amount calculation step is calculated by the following (1) formula i 3, The cross-sectional line length L of the cross-section i in the jth process calculated in the above cross-sectional line length calculating process is calculated by the following (2) i 4, According to the coefficient a in the formula (1), to which the uniform elongation rate of the material is set, according to the coefficient b in the formula (2) k , to which the material flow is set in the j-th process among all m times of the press process, the coefficient b k satisfies Σ j＝1 m (b k ) = 1, where 1 ≤ k ≤ m, L i 3 = L i 1 - L i 2 - a · El… (1) where 0 < a < 1, L i 4 = L i 2 +∑ k＝1 j (b k • L i 3)... (2) wherein 0≤b k ≤1.

7. A design method of a metal mold, characterized by comprising: a design method of a metal mold used when a metal plate is press-formed into a final part shape through a plurality of press processes, when one of the plurality of press processes is selected as a selection process and a part shape obtained in the selection process is selected as a selection part shape, one of the plurality of press processes selected and executed before the selection process is selected as a reference process, and a shape of the metal plate before press-formed in the reference process is selected as a reference shape, in the press processes from the reference process to the selection process, a press process including a draw forming is included, the design method of the metal mold includes: a cross section setting step of setting a line orthogonal to a direction in which material flows when the metal plate of the reference shape is draw-formed into the selection part shape through one process in a plan view, and setting a plurality of cross sections each cut by a plane orthogonal to the line in the plan view and extending in a direction along a thickness direction of the metal plate before formed; a flow amount calculation step of calculating, for each cross section, a flow amount of material required to form the reference shape into the selection part shape based on a cross-sectional line length of the selection part shape cut by the cross section, a cross-sectional line length in the reference shape cut by the same cross section as the cross section, and a uniform elongation of the material of the metal plate; a flow amount distribution step of distributing, for each cross section, the calculated flow amount to each process from the reference process to the selection process; a cross-sectional line length calculation step of calculating, for each cross section, a cross-sectional line length in each process from the reference process to the process before the selection process based on the distributed flow amount; and a shape determining step of determining a metal mold shape used in each process from the reference process to the process before the selection process based on the calculated cross-sectional line length.

8. The design method of a metal mold according to claim 7, characterized in that, the selection process is a final press process, and the reference process is an initial press process.

9. The design method of a metal mold according to claim 7 or 8, characterized in that, the protruding portion of the selection part shape extends toward a prescribed direction, and the selection part shape has a draw region in which material flows from a direction intersecting the prescribed direction in a plan view toward a position becoming the protruding portion when the metal plate is draw-formed into the selection part shape through one process, In the profile setting step, a line portion of the set line that passes through the drawing region is set as the line along the predetermined direction.

10. The design method of a metal mold according to claim 7 or 8, wherein The shape determining step has an adjustment step, wherein the adjustment step adjusts the length of the profile line length of each profile in each step from the reference step to the step prior to the selection step, without changing the total of the profile line lengths of each profile calculated by the profile line length calculating step, on the condition that The shape determining step determines the pre-mold shape after the press forming based on the profile line length of each profile adjusted by the adjustment step.

11. The design method of a metal mold according to claim 10, wherein In the adjustment step, the profile line length is adjusted based on the difference in the profile line length between adjacent profiles.

12. The design method of a metal mold according to claim 7 or 8, wherein In the case where the number of the plurality of sections is set to n, the index for identifying each section is set to i, and the line length in the above selected component shape cut by the same section is set to L for each section i 1 The line length in the above reference shape is set to L i 2 In the case where the uniform elongation of the material is set to El, the number of the press processes from the above reference process to the above selected process is set to m, and the index for identifying the press process is set to j, where 1≤i≤n and 1≤j≤m, The inflow amount L in the profile i calculated in the above inflow amount calculation step is calculated by the following (1) formula i 3, The cross-sectional line length L of the cross-section i in the jth process calculated in the above cross-sectional line length calculating process is calculated by the following (2) i 4, According to the coefficient a in the formula (1), to which the uniform elongation rate of the material is set, according to the coefficient b in the formula (2) k , to which the material flow is set in the j-th process among all m times of the press process, the coefficient b k satisfies Σ j＝1 m (b k ) = 1, where 1 ≤ k ≤ m, L i 3 = L i 1 - L i 2 - a · El… (1) 0 < a < 1, L i 4 = L i 2 +∑ k＝1 j (b k • L i 3)... (2) where 0≤b k ≤1.

13. A method of manufacturing a press part, characterized by using a metal mold designed by the design method of a metal mold according to any one of claims 7 to 12.

14. A metal mold shape design device, characterized by being a metal mold shape design device that calculates a metal mold shape of a metal mold used in each process other than a final press process when a metal plate is press formed into a final part shape through a plurality of press processes, selecting one process from the plurality of press processes as a selection process and setting a part shape obtained in the selection process as a selection part shape, selecting one press process from the plurality of press processes and executed prior to the selection process as a reference process, and setting a shape of a metal plate before press forming in the reference process as a reference shape, the press processes from the reference process to the selection process include a press process having a draw forming, the metal mold shape design device includes: a profile setting section that sets a line orthogonal to a direction in which material flows when a metal plate of the reference shape is draw formed into the selection part shape by one process in plan view, and sets a plurality of profiles cut by planes orthogonal to the line in plan view and extending in a direction along a plate thickness direction of the metal plate before forming; a flow amount calculating section that calculates, for each profile, a flow amount of material required to form the reference shape into the selection part shape based on a profile line length of the selection part shape cut by the profile, a profile line length in the reference shape cut by the same profile as the profile, and a uniform elongation of the material of the metal plate; a flow amount distributing section that distributes the calculated flow amount to each process from the reference process to the selection process for each profile; a profile line length calculating section that calculates, for each profile, a profile line length in each process from the reference process to the step prior to the selection process based on the distributed flow amount; and a profile line length calculating section that calculates, for each profile, a profile line length in each process from the reference process to the step prior to the selection process based on the distributed flow amount; and The shape determining section determines the metal mold shape in each process from the reference process to the process immediately before the selection process based on the calculated profile line length.

15. The metal mold shape designing apparatus according to claim 14, wherein The selection process is a final press process, and the reference process is an initial press process.

16. The metal mold shape designing apparatus according to claim 14 or 15, wherein The protruding portion of the selected component shape extends in a prescribed direction, and the selected component shape has a drawing region, wherein the drawing region is a region in which material flows from a direction intersecting the prescribed direction in plan view to a position becoming the protruding portion when the metal plate is drawn into the selected component shape by one process, The profile setting section sets a line portion passing through the drawing region in the set line as a line along the prescribed direction.

17. The metal mold shape designing apparatus according to claim 14 or 15, wherein The shape determining section has an adjusting section that adjusts the length of the profile line length of each profile in each process from the reference process to the process immediately before the selection process without changing the total of the profile line lengths of each profile calculated by the profile line length calculating section, The shape determining section determines the metal mold shape based on the profile line length of each profile adjusted by the adjusting section.

18. The metal mold shape designing apparatus according to claim 17, wherein In the adjusting section, the profile line length is adjusted based on the difference in profile line length between adjacent profiles.

19. The metal mold shape designing apparatus according to claim 14 or 15, wherein In the case where the number of the plurality of sections is set to n, the index for identifying each section is set to i, and the line length in the above selected component shape cut by the same section is set to L for each section i 1 The line length in the above reference shape is set to L i 2 In the case where the uniform elongation of the material is set to El, the number of the press processes from the above reference process to the above selected process is set to m, and the index for identifying the press process is set to j, where 1≤i≤n and 1≤j≤m, The inflow amount L in the profile i calculated by the inflow amount calculation section is calculated by the following (1) formula i 3, The cross-sectional line length L of the cross-section i in the jth process calculated by the cross-sectional line length calculation section is calculated by the following (2) i 4, According to the coefficient a in the formula (1), to which the uniform elongation rate of the material is set, according to the coefficient b in the formula (2) k , to which the material flow is set in the j-th process among all m times of the press processes, the coefficient b k satisfies Σ j＝1 m (b k ) = 1, where 1 ≤ k ≤ m, L i 3 = L i 1 - L i 2 - a · El… (1) 0 < a < 1, L i 4 = L i 2 +∑ k＝1 j (b k • L i 3)... (2) where 0≤b k ≤1.

20. A metal mold, comprising: The metal molds used in each process when a press component is manufactured by press forming a metal plate into a final component shape through a plurality of press processes, selecting one process from among the plurality of press processes as a selection process and the component shape obtained in the selection process as a selected component shape, selecting one press process from among the plurality of press processes and performed before the selection process as a reference process and the shape of the metal plate before press forming in the reference process as a reference shape, and including a press process having drawing in the press processes from the reference process to the selection process, for the forming surfaces of the metal molds used in each process from the reference process to the selection process, the forming surface of the metal mold of the selection process is shaped to follow the shape of the selected component shape, a line orthogonal in plan view to the direction in which material flows when the metal plate of the reference shape is drawn into the selected component shape by one process using the metal mold of the selection process is set, and a plurality of profiles cut by planes orthogonal in plan view to the line and extending in a direction along the thickness direction of the metal plate before forming are set, and the profile line length of each profile is calculated based on the set profiles. for each of the above cross sections arranged along the extension direction in the above line set, the material inflow amount of the material set in accordance with the cross section line length based on the above selected part shape cut by the cross section, the cross section line length in the above reference shape cut by the same cross section as the cross section, and the uniform elongation of the material of the above metal sheet, In the case where the number of the above-mentioned plurality of sections is n, the index for identifying each section is i, and the line length in the above-mentioned selected component shape cut by the same section is L i 1 The line length in the above-mentioned reference shape is L i 2 In the case where the uniform elongation of the material is El, the number of press processes from the above-mentioned reference process to the above-mentioned selected process is m, and the index for identifying the press process is j, where 1≤i≤n and 1≤j≤m, For the set inflow amount of the above-described material, the inflow amount L in the cross section i is set by the following (1) formula i 3, The cross-sectional line length L of the cross section i in the molding surface of the metal mold used in the jth process is represented by the following (2) i 4, coefficient b k satisfies ∑ j＝1 m (b k ) = 1, where 1≤k≤m, L i 3 = L i 1 - L i 2 - a · El… (1) where 0 < a < 1, L i 4 = L i 2 +∑ k＝1 j (b k • L i 3)... (2) where 0≤b k ≤1.

21. The metal mold according to claim 20, wherein the above selected process is the final press process, and the above reference process is the initial press process.

22. The metal mold according to claim 20 or 21, wherein the protruding portion of the above selected part shape extends toward a prescribed direction, and the above selected part shape has a drawing region that is a region in which material flows from a direction intersecting the above prescribed direction in plan view toward a position becoming the protruding portion when the metal sheet is drawn into the above selected part shape by one process, a line portion in the above line set passing through the above drawing region is set as a line along the above prescribed direction.

23. The metal mold according to claim 20 or 21, wherein in the molding surface of the metal mold of each of the above processes, the difference in cross section line length between adjacent cross sections is a predetermined set value or less.

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