Forming method for laminated member, laminated member press-formed by forming method, and manufacturing method for automobile component

Abstract

The present invention prevents plate members of a joined blank from separating in a region where the plate members are not pressed between a pad mold and a punch mold when a laminated member is press-formed from the joined blank. From a joined blank formed by overlapping and joining a first plate member, which is a metal plate member constituting a body component, with a second plate member, which is a metal plate member constituting a reinforcing component, a laminated member, which is formed by overlapping the reinforcing component having a U-shaped or L-shaped cross section inside the body component having a hat-shaped cross section, is integrally formed by press-forming. At this time, in a cross section orthogonal to a bending ridge line of the laminated member, the line length of a region corresponding to a curved section and a vertical wall section of the second plate member is set to be larger than or equal to the line length of a portion of the first plate member from an end of a top-plate corresponding region to the position where the first plate member is in contact with a shoulder section of a die mold when, during press-forming of the laminated member using a pair of a punch mold and the die mold, a mold surface, which is the extension of a flange forming surface of the punch mold, and an end of the first plate member come into contact with each other.

Description

Method for forming overlapping members, overlapping members press-formed by the method, and method for manufacturing automobile parts

[0001] The present invention relates to a method for press-forming a superposed member from a joined blank formed by overlapping and joining metal plate materials, and to a superposed member press-formed by the method. The present invention also relates to a method for manufacturing an automobile part including the superposed member.

[0002] Automotive structural components are required to suppress deformation of the vehicle body during a collision and to protect the interior space of the vehicle by absorbing collision energy. In recent years, efforts have been made to increase the strength and performance of structural components in order to achieve even better collision safety.

[0003] Many frame components are formed from elongated members with hat-shaped or U-shaped cross sections. One way to improve the performance of such components is to overlap and join reinforcing parts to the outside or inside of the main body part.

[0004] Generally, members having such an overlapping structure are manufactured by press-forming the main body part and the reinforcing part separately from metal plates, then holding them in an overlapping state and joining them by various methods such as spot welding.In addition, a method has been proposed in which metal plates are overlapped in advance before forming the two parts, and then both parts are simultaneously press-formed from the overlapping metal plates to manufacture them as an integrated unit.

[0005] For example, Patent Document 1 describes a method for overlapping a metal plate material that will become a main component and a metal plate material that will become a reinforcing component, and then bulging-forming an overlapping member from them. In this method, a second plate material that is smaller in area and thicker than the first plate material is joined to the back surface of the first plate material in the bulging direction. Then, with the outer edge of the first plate material restrained, the main component is bulged from the first plate material, while the reinforcing component is formed from the second plate material without restraint.

[0006] Japanese Patent Application Laid-Open No. 2002-192245

[0007] In the method described in Patent Document 1, when press-forming overlapping members having a hat-shaped or U-shaped cross section to form a frame part, the region corresponding to the top plate of the plate material is curved during forming of the main body part, which poses a problem that the shape of the overlapping members deviates significantly from the correct dimensions due to springback after demolding.

[0008] One method for solving the above problem is a press-forming method in which a region of a plate material corresponding to a top plate portion is clamped between a pad die and a punch die, while the punch die and die are used to bulge and form a main body component, thereby suppressing curvature in the region corresponding to the top plate portion. However, when this press-forming method is used to integrally mold overlapping components having a hat-shaped or U-shaped cross section, the region corresponding to the top plate portion is clamped between the pad die and the punch die. However, in the regions corresponding to the bend ridges and vertical walls that are not clamped between the pad die and the punch die, separation between the first plate material constituting the main body component and the second plate material constituting the reinforcing component may occur during molding. In this case, a gap may form between the main body component and the reinforcing component after demolding, which can reduce the performance of the overlapping component or hinder assembly.

[0009] Therefore, an object of the present invention is to provide a molding method for integrally press-molding an overlapping member composed of a main body part having a hat-shaped or U-shaped cross section and a reinforcing part having a U-shaped or L-shaped cross section, which solves the above-mentioned problems. It is also an object of the present invention to provide an overlapping member press-molded by this molding method. It is also an object of the present invention to provide a method for manufacturing an automotive part including this overlapping member.

[0010] To solve the above-mentioned problems, the inventors conducted the following study. First, a metal plate material constituting a main body component having a hat-shaped or U-shaped cross-section was designated as the first plate material, and a metal plate material constituting a reinforcing component having a U-shaped or L-shaped cross-section was designated as the second plate material. A region of the first plate material corresponding to the top plate portion of the main body component and a region of the second plate material corresponding to the top plate portion of the reinforcing component were clamped between a pad mold and a punch mold. Then, the first and second plate materials were press-molded using a punch mold and a die mold to integrally form a laminated member of the main body component and the reinforcing component. The linear lengths of the first and second plate materials during this molding process were varied, and the deflection of each plate material during molding in a cross section perpendicular to the bending ridge of the laminated member was calculated. After careful study of the results, the inventors discovered the following two types of modes in which separation of the two plate materials occurs.

[0011] In a first embodiment, the main body part has a hat-shaped cross section having a top plate portion, a vertical wall portion, and a flange portion connected to each other by a bending ridge portion, and the reinforcing part has a U-shaped or L-shaped cross section having a top plate portion and a vertical wall portion connected to each other by the bending ridge portion. During the forming of the overlapping member until the end of the first plate material contacts a mold surface that is an extension of the flange-forming surface of the punch mold that forms the flange portion, the linear length of the region of the second plate material that is not clamped during forming, i.e., the total linear length corresponding to the bending ridge portion and the vertical wall portion after forming, is shorter than the linear length from the end of the region of the first plate material that corresponds to the top plate portion to the contact position with the shoulder of the die mold.

[0012] In a second embodiment, the main body part has a U-shaped cross section having a top plate and a vertical wall connected to each other by a bending ridge, and the reinforcing part has a U-shaped or L-shaped cross section having a top plate and a vertical wall connected to each other by a bending ridge. During the molding of the overlapping member until the inclination angle of the first plate at the position where the shoulder of the die mold and the first plate contact each other matches the inclination angle of the molding surface of the vertical wall of the die mold, the linear length of the region of the second plate that is not clamped during molding, i.e., the total linear length corresponding to the bending ridge and the vertical wall after molding, becomes shorter than the linear length from the end of the region of the first plate that corresponds to the top plate to the position where the first plate contacts the shoulder of the die mold.

[0013] In order to solve the above-mentioned problems, the present invention has the following configuration. First, let X be the ratio of the line length corresponding to the vertical wall portion of the second plate material after forming to the line length corresponding to the vertical wall portion of the first plate material after forming in a cross section perpendicular to the bending ridge of the overlapping member. Attention was focused on the condition that the rising angle Y of the vertical wall portion relative to the top plate portion of the overlapping member must satisfy. The conditional expressions were derived for the first and second embodiments. The method for deriving the conditional expressions is described below with reference to FIGS. 5 to 11. Note that even if the rising angle Y of the vertical wall portion relative to the top plate portion of the overlapping member is significantly inclined from 90 degrees, the wall portion connected to the top plate portion via the bending ridge will be referred to as the "vertical wall portion" for convenience in this specification.

[0014] 5 shows a schematic cross-sectional view of the first embodiment at the moment when the die surface, which is an extension of the flange-forming surface of the punch die T1, comes into contact with the end of the first plate material L constituting the main body component. At this time, the first plate material L, which is the metal plate material constituting the main body component, and the second plate material P, which is the metal plate material constituting the reinforcing component, are sandwiched and compressed between the punch die T1 and the pad die T3 in a region corresponding to the top plate portion. The end of the first plate material L is in contact with the die surface, which is an extension of the flange-forming surface of the punch die T1.

[0015] The height of the main body part is L H and the rising angle of the vertical wall portion with respect to the top plate portion of the overlapping member is Y, the distance L in FIG. ０ can be expressed by the following formula (3).

[0016] The position where the shoulder of the die mold T2 and the first plate material L first come into contact is defined as the origin O, and the horizontal distance from the origin O toward the center of the part is defined as z. At this time, the vertical deflection f(z) of the first plate material L and the second plate material P at the distance z is calculated by the following equation: ０ and C １ This can be expressed by the following equation (4).

[0017] However, C １is a coefficient that reflects the magnitude of the deflection deformation of the first plate material L and the second plate material P. In this embodiment, it is a value that represents the deflection deformation at the moment when the die surface, which is an extension of the flange portion forming surface of the punch die T1, comes into contact with the end of the first plate material L. Hereinafter, C １ The process of deriving is explained below.

[0018] FIG. 6 shows a cross-sectional schematic diagram of the linear length of a metal plate per unit length in the horizontal direction when the plate is bent. The bent plate has a curved shape. However, it can be approximated as a straight line per unit length. Therefore, using the vertical deflection f(i) of the first and second plates at z=i and the vertical deflection f(i+1) of the first and second plates at z=i+1, the linear length L of the plate per unit length in the horizontal direction can be calculated. ｉ can be expressed by the following formula (5).

[0019] In FIG. 5, the line length L from the end of the top plate portion of the first plate L to the contact position between the first plate L and the die T2 is Ｐ is from z=0 to z=L ０ Line length L per unit length in the horizontal direction up to ｉ Since it is the sum of the above, it can be expressed by the following formula (6).

[0020] When attention is paid to the first plate material L in this embodiment, the vertical component of the line length of the region of the first plate material L that is not clamped in FIG. 5 is the height L of the main body part. H Therefore, the linear length of the region of the first plate L that is not clamped, that is, the total linear length of the curved portion excluding the top plate portion and its extension, is defined as L Ｍ and the inclination angle of the first plate material L at the contact position between the first plate material L and the die mold T2 is θ, the following equation (7) holds true. Here, θ is calculated using the following formula (8).

[0021] C １ is derived by recursively calculating a value that satisfies the formulas (3) to (8). １In this embodiment, the bending deformation of the first plate L and the second plate P is derived by using the above equation. In this embodiment, the minimum line length of the region that is not clamped during forming, which is required for the second plate P to prevent separation, is the line length L in FIG. Ｐ Therefore, C １ It is derived using equation (6) when

[0022] Using this derivation method, the dimensions of the first plate material L and the second plate material P in the first form were variously changed, and the relationship between the ratio X of the line length P1 corresponding to the vertical wall portion of the second plate material P to the line length L1 corresponding to the vertical wall portion of the first plate material L, and the angle Y of the vertical wall portion relative to the top plate portion of the overlapping member was calculated.

[0023] 1 shows a schematic diagram of a cross section perpendicular to the bending ridge of the overlapping member according to the first embodiment. In this embodiment, line length L1 is the length of a line connecting the intersection of an extended straight line between the top plate portion and vertical wall portion of the first plate L and the intersection of an extended straight line between the vertical wall portion and flange portion of the first plate L. Line length P1 is the length of a line from the end of the top plate portion of the second plate P to the end of the second plate P.

[0024] Table 1 shows the line length L excluding the top plate portion of the main body part for shapes A and B considered as examples in the first embodiment. Ｍ The table shows the length (mm) of the vertical wall portion of the main body part, the length (mm) of the vertical wall portion of the reinforcing part, the ratio X of the vertical wall portion length, and the angle Y of the vertical wall portion.

[0025] Based on the results of X and Y shown in Table 1 derived from this embodiment, the conditional expression (1) was derived. FIG. 7 shows a plot of the ratio X of the vertical wall length and the angle Y of the vertical wall for shapes A and B of the examples considered in the first embodiment, and conditional expression (1).

[0026] 8 shows a cross-sectional view of the second embodiment at the moment when the inclination angle of the first plate material L constituting the main component at the contact point between the die T2 and the die T2 coincides with the inclination angle of the vertical wall of the die T2. At this time, the first plate material L, which is a metal plate material constituting the main component, and the second plate material P, which is a metal plate material constituting the reinforcing component, are sandwiched between the punch T1 and the pad T3 in a region corresponding to the top plate. The inclination angle θ of the first plate material L with respect to the top plate surface at the contact point between the die T2 and the die T2 is equal to the rising angle Y of the vertical wall of the overlapping member with respect to the top plate.

[0027] The height of the main body part is L H and the rising angle of the vertical wall portion with respect to the top plate portion of the overlapping member is Y, L in FIG. ０ can be expressed by the following formula (3).

[0028] The position where the shoulder of the die T2 and the first plate L first come into contact is defined as the origin O, and the horizontal distance from the origin O to the center of the main body part is defined as z. The vertical deflection f(z) of the first plate L and the second plate P at the distance z is expressed as the distance L ０ and C ２ This can be expressed by the following equation (9).

[0029] However, C ２ is a coefficient that reflects the magnitude of the deflection deformation of the first plate L and the second plate P. In this embodiment, the inclination angle θ of the first plate L with respect to the top plate surface at the point where the die T2 and the first plate L come into contact is a value that is the deflection deformation at the moment when the rising angle of the vertical wall portion with respect to the top plate portion of the overlapping member becomes equal to Y. Hereinafter, C ２ The process of deriving is explained below.

[0030] In this embodiment, the following equality (10) holds true. Here, θ is calculated using the following formula (8).

[0031] C ２ is calculated recursively as a value that satisfies the formulas (3), (8), (9), and (10).２ In this embodiment, the bending deformation of the first plate L and the second plate P is derived by using the formula: In this embodiment, the minimum line length of the region that is not clamped during forming, which is required for the second plate P to prevent separation, is the line length L in FIG. Ｐ Therefore, C ２ It is derived using equation (6) when

[0032] Using this derivation method, the dimensions of the first plate material L and the second plate material P in the second form were variously changed, and the relationship between the ratio X of the line length P2 corresponding to the vertical wall portion of the second plate material P to the line length L2 corresponding to the vertical wall portion of the first plate material L, and the angle Y of the vertical wall portion relative to the top plate portion of the overlapping member was calculated.

[0033] 3 shows a schematic diagram of a cross section perpendicular to the bending ridge of the overlapping member according to the second embodiment. In this embodiment, the line length L2 is the line length connecting the intersection point of the extension of the straight line between the top plate portion and the vertical wall portion of the first plate L and the end of the first plate L, and the line length P2 is the line length from the end of the top plate portion of the second plate P to the end of the second plate P.

[0034] Table 2 shows a list of the vertical wall lengths (mm) of the main body part, the vertical wall lengths (mm) of the reinforcing part, the ratio X of the vertical wall lengths, and the angle Y of the vertical wall parts for shapes C and D considered as examples in the second embodiment.

[0035] Based on the results of X and Y shown in Table 2 derived from this embodiment, the conditional formula (2) was developed. However, 0<Y≦90. Fig. 9 shows a plot of the ratio X of the vertical wall length and the angle Y of the vertical wall portion in the case studied in the second embodiment, and conditional expression (2).

[0036] The method for forming a superposed member of the present invention corresponding to the first aspect described above includes the steps of: forming a superposed member in which a main body part has a hat-shaped cross section, the main body part having a top plate portion, a vertical wall portion, and a flange portion connected to each other at a bending ridge portion, and a reinforcing part having a U-shaped or L-shaped cross section, the top plate portion and the vertical wall portion connected to each other at a bending ridge portion, are superposed on the inside of the main body part; and forming the superposed member integrally from a joined blank in which a first plate material, which is a metal plate material constituting the main body part, and a second plate material, which is a metal plate material constituting the reinforcing part, are joined together by pressing the joined blank in a state in which regions of the joined blank corresponding to the top plate portions of the main body part and the reinforcing part are clamped; In a cross section perpendicular to the bending ridge of the overlapping member, the linear length of the region of the second plate material corresponding to the bending ridge and the vertical wall of the reinforcing part is made equal to or greater than the linear length from the end of the region of the first plate material corresponding to the top plate portion of the main body part to the contact position with the shoulder of the die mold when the die surface extending from the flange forming surface of the punch mold comes into contact with the plate end of the first plate material during press molding of the joined blank using a pair of punch molds and die molds.

[0037] In addition, the method for molding an overlapping member of the present invention corresponding to the first embodiment described above is a problem-solving means in which, in a cross section perpendicular to the bending ridge of the overlapping member, when the ratio of the line length of the second plate material corresponding to the vertical wall portion of the reinforcing part to the line length of the region of the first plate material corresponding to the vertical wall portion of the main body part is X, the rise angle Y (degrees) of the vertical wall portion relative to the top plate part of the overlapping member satisfies the following formula (1):

[0038] Furthermore, the overlapping member of the present invention corresponding to the first embodiment is an overlapping member in which a reinforcing part having a U-shaped or L-shaped cross section, which also has a top plate portion and a vertical wall portion connected to each other at a bending ridge portion, is overlapped on the inside of a main part having a hat-shaped cross section, which has a top plate portion, a vertical wall portion, and a flange portion connected to each other at a bending ridge portion, and the overlapping member is an overlapping member integrally formed by press-molding a joined blank in which a first plate material that is a metal plate material constituting the main part and a second plate material that is a metal plate material constituting the reinforcing part are overlapped and joined, with regions of the joined blank corresponding to the top plate portions of the main part and the reinforcing part being clamped, In a cross section perpendicular to the bending ridge of the overlapping member, the linear length of the region of the second plate material corresponding to the bending ridge and the vertical wall of the reinforcing part is equal to or greater than the linear length from the end of the region of the first plate material corresponding to the top plate portion of the main body part to the contact position with the shoulder of the die mold when the die surface extending from the flange forming surface of the punch mold comes into contact with the plate end of the first plate material during press forming from the joined blank using a punch mold and a die mold.

[0039] In addition, in the overlapping member of the present invention corresponding to the first form described above, when the ratio of the line length of the region of the second plate material corresponding to the vertical wall portion of the reinforcing part to the line length of the region of the first plate material corresponding to the vertical wall portion of the main body part in a cross section perpendicular to the bending ridge portion of the overlapping member is X, the rise angle Y of the vertical wall portion relative to the top plate portion of the overlapping member becomes a preferable problem-solving means that satisfies the above formula (1).

[0040] On the other hand, the method for forming a superposed member of the present invention corresponding to the second embodiment includes a method for integrally forming a superposed member, in which a reinforcing part having a U-shaped or L-shaped cross section, the reinforcing part having a top plate portion and a vertical wall portion connected to each other at a bending ridge portion, superposed on the inside of a main part having a U-shaped cross section, the top plate portion and the vertical wall portion connected to each other at a bending ridge portion, from a joined blank formed by overlapping and joining a first plate material that is a metal plate material constituting the main part and a second plate material that is a metal plate material constituting the reinforcing part, by press forming the joined blank in a state in which regions of the joined blank corresponding to the top plate portions of the main part and the reinforcing part are clamped and pressed, In a cross section perpendicular to the bending ridge of the overlapping member, the linear length of the region of the second plate material corresponding to the bending ridge and the vertical wall of the reinforcing part is made equal to or greater than the linear length from the end of the region of the first plate material corresponding to the top plate portion of the main body part to the contact position with the shoulder of the die mold when the inclination angle of the first plate material at the position where the shoulder of the die mold contacts the first plate material matches the inclination angle of the vertical wall of the die mold during press molding of the joined blank using a pair of punch molds and die molds.

[0041] In addition, the method for molding an overlapping member of the present invention corresponding to the second form described above is a problem-solving means in which, in a cross section perpendicular to the bending ridge of the overlapping member, when the ratio of the line length of the region of the second plate material corresponding to the vertical wall portion of the reinforcing component to the line length of the region of the first plate material corresponding to the vertical wall portion of the main body component is X, the rise angle Y (degrees) of the vertical wall portion relative to the top plate portion of the overlapping member preferably satisfies the following formula (2): However, 0<Y≦90.

[0042] Furthermore, the overlapping member of the present invention corresponding to the second embodiment is an overlapping member in which a reinforcing part having a U-shaped or L-shaped cross section, also having a top plate portion and a vertical wall portion connected to each other at a bending ridge portion, is overlapped on the inside of a main part having a U-shaped cross section, the top plate portion and the vertical wall portion connected to each other at a bending ridge portion, and the overlapping member is integrally formed by press-forming a joined blank in which a first plate material that is a metal plate material constituting the main part and a second plate material that is a metal plate material constituting the reinforcing part are overlapped and joined, with regions of the joined blank corresponding to the top plate portions of the main part and the reinforcing part being clamped, In a cross section perpendicular to the bending ridge of the overlapping member, the linear length of the region of the second plate material corresponding to the bending ridge and the vertical wall of the reinforcing part is greater than or equal to the linear length from the end of the region of the first plate material corresponding to the top plate portion of the main body part to the contact position with the shoulder of the die mold when the inclination angle of the first plate material at the position where the shoulder of the die mold contacts the first plate material matches the inclination angle of the vertical wall of the die mold during press molding of the joined blank using a pair of punch molds and die molds.

[0043] In addition, in the overlapping member of the present invention corresponding to the second form described above, when the ratio of the line length of the region of the second plate material corresponding to the vertical wall portion of the reinforcing part to the line length of the region of the first plate material corresponding to the vertical wall portion of the main body part in a cross section perpendicular to the bending ridge portion of the overlapping member is X, the rise angle Y (degrees) of the vertical wall portion relative to the top plate portion of the overlapping member becomes a preferable problem-solving means that satisfies the above formula (2).

[0044] Furthermore, a method for manufacturing an automobile part including a superposed member of any of the above embodiments is characterized by including a step of molding the superposed member based on the method for molding a superposed member of any of the above embodiments.

[0045] The overlapping member forming method of the present invention and the overlapping member press-formed by the forming method of the present invention provide the following advantages. A joined blank is formed by overlapping and joining a first metal plate constituting a main component with a second metal plate constituting a reinforcing component. The regions of the joined blank corresponding to the top plate portions of the main component and the reinforcing component are clamped between a pad die and a punch die. When the joined blank is integrally press-formed into an overlapping member, separation between the first and second plate members is prevented in the regions not clamped between the pad die and the punch die during forming. This prevents gaps from forming between the main component and the reinforcing component after demolding, thereby avoiding performance degradation of the overlapping member and assembly problems. Automotive components including such overlapping members can be used in automotive frame components, contributing to higher strength and performance of the frame components and achieving superior crashworthiness.

[0046] 1 is a schematic diagram of a cross section perpendicular to a bend ridgeline portion of a superposed member according to a first embodiment. FIG. 2 is a graph showing the relationship between the ratio X of the line length of the vertical wall portion of the reinforcing component to the line length of the vertical wall portion of the main body component, and the rise angle Y of the vertical wall portion relative to the top plate portion of the component, which is satisfied by embodiment 1 of the present invention. FIG. 3 is a schematic diagram of a cross section perpendicular to a bend ridgeline portion of a superposed member according to a second embodiment. FIG. 4 is a graph showing the relationship between the ratio X of the line length of the vertical wall portion of the reinforcing component to the line length of the vertical wall portion of the main body component, and the rise angle Y of the vertical wall portion relative to the top plate portion of the component, which is satisfied by embodiment 2 of the present invention. FIG. 4 is a schematic cross-sectional view of the moment when a die surface extending from a flange forming surface of a punch die according to the first embodiment comes into contact with an end of a first plate material constituting the main body component. FIG. 5 is a schematic cross-sectional view of the plate material line length per unit length in the horizontal direction at point z = i when the first and second plate materials are bent. FIG. 6 is a graph showing a plot of the ratio X of the vertical wall portion length and the angle Y of the vertical wall portion for cases considered in the first embodiment, and conditional formula (1). 1 is a schematic cross-sectional view of the moment when the inclination angle of the first plate material constituting the main body part at the position where the die mold and the first plate material contact each other matches the inclination angle of the vertical wall portion of the die mold in the second embodiment.

[0023] FIG. 1 is a graph showing a plot of the ratio X of the vertical wall portion length and the angle Y of the vertical wall portion for the case examined in the second embodiment, and conditional formula (2). (a) is a perspective view showing a superposed member of an example according to embodiment 1 of the present invention, (b) is a cross-sectional view showing a schematic half of the superposed member, and (c) is a perspective view showing a reinforcing member in the superposed member.

[0024] FIG. 1 is a graph showing a plot of the ratio X of the vertical wall portion length and the angle Y of the vertical wall portion for test Nos. 1 to 4 according to embodiment 1.

[0025] FIG. 2 is a cross-sectional view of test Nos. 1 to 4 according to embodiment 1 during molding and after demolding.

[0026] FIG. 3 is a perspective view showing a superposed member of an example according to embodiment 2 of the present invention, (b) is a cross-sectional view showing a schematic half of the superposed member, and (c) is a perspective view showing a reinforcing member in the superposed member.

[0027] FIG. 4 is a graph showing a plot of the ratio X of the vertical wall portion length and the angle Y of the vertical wall portion for test Nos. 1 to 4 according to embodiment 1 during molding and after demolding.

[0028] FIG. 5 is a perspective view showing a superposed member of an example according to embodiment 2 of the present invention, (b) is a cross-sectional view showing a schematic half of the superposed member, and (c) is a perspective view showing a reinforcing member in the superposed member.

[0029] FIG. 6 is a graph showing a plot of the ratio X of the vertical wall portion length and the angle Y of the vertical wall portion for 1 is a graph showing a plot of the ratio X of the vertical wall length and the angle Y of the vertical wall for Test Nos. 5 to 8. FIG. 2 is a cross-sectional view of Test Nos. 5 to 8 according to embodiment 1 during molding and after demolding.

[0047] Embodiments of the present invention will be described in detail below with reference to the drawings. <Embodiment 1> Fig. 1 shows a schematic diagram of a cross section perpendicular to a bending ridge of a first embodiment of a laminated member. The laminated member here is composed of a first plate L, which is a metal plate constituting a main body component having a hat-shaped cross section, and a second plate P, which is a metal plate constituting a reinforcing component having a U-shaped or L-shaped cross section. In the cross section perpendicular to the bending ridge, the vertical wall portion is bent at an angle Y (degrees) relative to the top plate portion. The line length corresponding to the vertical wall portion of the first plate L is L1, and the line length corresponding to the vertical wall portion of the second plate P is P1.

[0048] Figure 2 shows the relationship between the ratio X of the line length P1 of the vertical wall portion of the reinforcing component to the line length L1 of the vertical wall portion of the main body component, and the angle Y of the vertical wall portion relative to the top plate portion of the overlapping member, which is satisfied by this embodiment 1 related to the first form. X is the ratio calculated by dividing the line length P1 corresponding to the vertical wall portion of the second plate material P constituting the reinforcing component in Figure 1 by the line length L1 corresponding to the vertical wall portion of the first plate material L constituting the main body component. Y is the rising angle of the vertical wall portion relative to the top plate portion in Figure 1.

[0049] The preferred range of the rise angle Y that can prevent separation of the first plate material L and the second plate material P during molding varies with changes in the ratio X of the line length of the vertical wall portion of the reinforcing component to the line length of the vertical wall portion of the main body component. The relational expression between the two that indicates this preferred range satisfies the following formula (1):

[0050] According to the first embodiment, for example, when the ratio X of the line length P1 of the vertical wall portion of the reinforcing component to the line length L1 of the vertical wall portion of the main body component is 0.6, the rising angle Y of the vertical wall portion needs to be 60 degrees or more. In this case, separation of the first plate material L and the second plate material P during molding is suppressed. Therefore, no gap is generated between the main body component and the reinforcing component after demolding.

[0051] Fig. 10(a) is a perspective view showing an overlapping member of an example according to the first embodiment. Fig. 10(b) is a cross-sectional view showing a schematic half of the overlapping member. Fig. 10(c) is a perspective view showing a reinforcing member in the overlapping member. This overlapping member has a shape in which a constant cross section perpendicular to the bending ridge is extruded 120 mm in a direction along the bending ridge, with the top plate and flange portions horizontal and the vertical wall portion rising at an angle of 60 degrees from the top plate.

[0052] The dimensions of the first plate material L constituting the main body component in the above cross section were: the length of the top plate portion was 90 mm, the distance between the R ends of the vertical wall portions was 62 mm, and the length of the flange portion was 20 mm. The outer radius of the bent ridge portion connecting the top plate portion and the vertical wall portions was 8.0 mm, and the inner radius of the bent ridge portion connecting the vertical wall portions and the flange portion was 6.0 mm. The dimensions of the second plate material P constituting the reinforcing component in the above cross section were: the length of the top plate portion was 90 mm, and the distance from the R end of the vertical wall portions to the plate end was 22 to 50 mm. The inner radius of the bent ridge portion connecting the top plate portion and the vertical wall portions was 5.0 mm.

[0053] In this embodiment, the line length L1 corresponding to the vertical wall portion of the main body part of the first plate material L is the line length connecting point U and point S, where U is the intersection point of the extension of the straight line portions of the top plate portion and the vertical wall portion, and S is the intersection point of the extension of the straight line portions of the vertical wall portion and the flange portion. Furthermore, the line length P1 corresponding to the vertical wall portion of the reinforcing part of the second plate material P is the line length from the boundary point E between the top plate portion and the bending ridge portion to the end point F of the plate material.

[0054] The first plate material L constituting the main body component was a hot-dip galvanized steel sheet with a tensile strength of 980 MPa and a thickness of 1.4 mm, and the second plate material P constituting the reinforcing component was a cold-rolled steel sheet with a tensile strength of 1470 MPa and a thickness of 1.6 mm.

[0055] Table 3 shows a list of Test Nos. 1 to 4 according to the first embodiment.

[0056] Fig. 11 shows a plot of the ratio X of the vertical wall length and the angle Y of the vertical wall for Test Nos. 1 to 4 according to embodiment 1. Fig. 12 also shows cross-sectional views of Test Nos. 1 to 4 according to embodiment 1 during molding and after demolding.

[0057] In Test No. 1, the length of the first plate material L corresponding to the vertical wall portion of the main body component was 70 mm, and the line length of the second plate material P corresponding to the vertical wall portion of the reinforcing component was 28 mm. As a result, the ratio X of the vertical wall length of the second plate material P to the first plate material L was X = 0.40. In this case, the angle Y of the vertical wall portion derived from conditional formula (1) was Y ≥ 72.2 degrees. However, in Test No. 1, the angle Y of the vertical wall portion was set to 60 degrees, which did not satisfy conditional formula (1), and separation occurred during molding.

[0058] In Test No. 2, the length of the first plate L corresponding to the vertical wall portion of the main body component was 70 mm, and the line length of the second plate P corresponding to the vertical wall portion of the reinforcing component was 35 mm. As a result, the ratio X of the vertical wall length of the second plate P to the first plate L was X = 0.50. In this case, the angle Y of the vertical wall portion derived from conditional formula (1) was Y ≥ 66.5 degrees. However, in Test No. 2, the angle Y of the vertical wall portion was set to 60 degrees, which did not satisfy conditional formula (1), and separation occurred during molding.

[0059] In Test No. 3, the length of the first plate material L corresponding to the vertical wall portion of the main body component was 70 mm, and the line length of the second plate material P corresponding to the vertical wall portion of the reinforcing component was 42 mm. As a result, the ratio X of the vertical wall length of the second plate material P to the first plate material L was X = 0.60. In this case, the angle Y of the vertical wall portion derived from conditional formula (1) was Y ≥ 59.8 degrees. In Test No. 3, the angle Y of the vertical wall portion was set to 60 degrees, which satisfied conditional formula (1), and no separation occurred during molding.

[0060] In Test No. 4, the length of the first plate material L corresponding to the vertical wall portion of the main body component was 70 mm, and the line length of the second plate material P corresponding to the vertical wall portion of the reinforcing component was 56 mm. As a result, the ratio X of the vertical wall length of the second plate material P to the first plate material L was X = 0.80. In this case, the angle Y of the vertical wall portion derived from conditional formula (1) was Y ≥ 43.4 degrees. In Test No. 4, the angle of the vertical wall portion was set to 60 degrees, which satisfied conditional formula (1), and no separation occurred during molding.

[0061] 3 shows a schematic diagram of a cross section perpendicular to the bending ridge of a second embodiment of the overlapping member. The overlapping member here is composed of a first plate L, which is a metal plate constituting a main body component having a U-shaped cross section, and a second plate P, which is a metal plate constituting a reinforcing component having a U-shaped or L-shaped cross section. In the cross section perpendicular to the bending ridge, the vertical wall portion is bent at an angle Y (degrees) relative to the top plate portion. The line length corresponding to the vertical wall portion of the first plate L is L2, and the line length corresponding to the vertical wall portion of the second metal plate is P2.

[0062] Figure 4 shows the relationship between the ratio X of the line length P2 of the vertical wall portion of the reinforcing component to the line length L2 of the vertical wall portion of the main body component, and the angle Y of the vertical wall portion relative to the top plate portion of the overlapping member, which is satisfied by this second embodiment related to the second configuration. X is the ratio calculated by dividing the line length P2 corresponding to the vertical wall portion of the second plate material P constituting the reinforcing component in Figure 3 by the line length L2 corresponding to the vertical wall portion of the first plate material L constituting the main body component. Y is the rising angle of the vertical wall portion relative to the top plate portion in Figure 3.

[0063] The preferred range of the rise angle Y that can suppress separation of the first plate material L and the second plate material P during molding changes with changes in the ratio X of the line length of the vertical wall portion of the reinforcing part to the line length of the vertical wall portion of the main body part, and the relationship between the two that indicates the preferred range satisfies the following equation (2). However, 0<Y≦90.

[0064] According to the second embodiment, for example, when the ratio X of the line length of the vertical wall portion of the reinforcing component to the line length of the vertical wall portion of the main component is 0.8, the rising angle of the vertical wall portion needs to be 54 degrees or more. In this case, separation of the first plate material L and the second plate material P during molding is suppressed. Therefore, no gap is generated between the main component and the reinforcing component after demolding.

[0065] Fig. 13(a) is a perspective view showing an overlapping member of an example according to the second embodiment. Fig. 13(b) is a cross-sectional view showing a schematic half of the overlapping member. Fig. 13(c) is a perspective view showing a reinforcing member in the overlapping member. This overlapping member has a shape in which a constant cross section perpendicular to the bending ridge is extruded 120 mm in a direction along the bending ridge, with the top plate being horizontal and the vertical wall portion rising at an angle of 60 degrees from the top plate.

[0066] The dimensions of the first plate material L constituting the main body component in the cross section were a top plate length of 90 mm, a distance between the R ends of the vertical wall portions of 65 mm, and an outer bend radius of the bent ridge portion connecting the top plate portion and the vertical wall portions of 8.0 mm. The dimensions of the second plate material P constituting the reinforcing component in the cross section were a top plate length of 90 mm, and a distance from the R end of the vertical wall portions to the plate end of 22 to 57 mm. The inner bend radius of the bent ridge portion connecting the top plate portion and the vertical wall portions of 5.0 mm.

[0067] In this embodiment, the line length L2 of the first plate L corresponding to the vertical wall portion of the main body part is the line length connecting point U and the plate end point of the first plate L, when U is the intersection point of the extended straight line portions of the top plate portion and the vertical wall portion. Furthermore, the line length P2 of the second plate P corresponding to the vertical wall portion of the reinforcing part is the line length from the boundary point E between the top plate portion and the bending ridge portion to the end point F of the plate.

[0068] The first plate material L constituting the main body component was a hot-dip galvanized steel sheet with a tensile strength of 980 MPa and a thickness of 1.4 mm, and the second plate material P constituting the reinforcing component was a cold-rolled steel sheet with a tensile strength of 1470 MPa and a thickness of 1.6 mm.

[0069] Table 4 shows a list of Test Nos. 5 to 8 according to this embodiment 2.

[0070] Fig. 14 shows a plot of the ratio X of the vertical wall length and the angle Y of the vertical wall for Test Nos. 5 to 8 according to embodiment 2. Fig. 15 shows cross-sectional views of Test Nos. 5 to 8 according to embodiment 2 during molding and after demolding.

[0071] In Test No. 5, the length of the first plate L corresponding to the vertical wall portion of the main body component was 70 mm, and the line length of the second plate P corresponding to the vertical wall portion of the reinforcing component was 28 mm. As a result, the ratio X of the vertical wall length of the second plate P to the first plate L was X = 0.40. In this case, the angle Y of the vertical wall portion derived from conditional formula (2) was Y ≥ 132 degrees. However, in Test No. 5, the angle Y of the vertical wall portion was set to 60 degrees, which did not satisfy conditional formula (2), and separation occurred during molding.

[0072] In Test No. 6, the length of the first plate L corresponding to the vertical wall portion of the main body component was 70 mm, and the line length of the second plate P corresponding to the vertical wall portion of the reinforcing component was 42 mm. As a result, the ratio X of the vertical wall length of the second plate P to the first plate L was X = 0.60. In this case, the angle Y of the vertical wall portion derived from conditional formula (2) was Y ≥ 93 degrees. However, in Test No. 6, the angle Y of the vertical wall portion was set to 60 degrees, which did not satisfy conditional formula (2), and separation occurred during molding.

[0073] In Test No. 7, the length of the first plate L corresponding to the vertical wall portion of the main body component was 70 mm, and the line length of the second plate P corresponding to the vertical wall portion of the reinforcing component was 56 mm. As a result, the ratio X of the vertical wall length of the second plate P to the first plate L was X = 0.80. In this case, the angle Y of the vertical wall portion derived from conditional formula (2) was Y ≥ 54 degrees. In Test No. 7, the angle of the vertical wall portion was set to 60 degrees, which satisfied conditional formula (2) and did not cause separation during molding.

[0074] In Test No. 8, the length of the first plate material L corresponding to the vertical wall portion of the main body component was 70 mm, and the line length of the second plate material P corresponding to the vertical wall portion of the reinforcing component was 63 mm. As a result, the ratio X of the vertical wall length of the second plate material P to the first plate material L was X = 0.90. In this case, the angle Y of the vertical wall portion derived from conditional formula (2) was Y ≥ 35 degrees. In Test No. 8, the angle Y of the vertical wall portion was set to 60 degrees, which satisfied conditional formula (2) and did not cause separation during molding.

[0075] Although the embodiments of the present invention have been described above, the overlapping member molding method of the present invention and the overlapping member of the present invention press-molded by the molding method are not limited to the above-described embodiments. The present invention can be modified as appropriate within the scope of the claims. For example, the overlapping member of the present invention is not limited to automobile bodies, but may also be used for motorcycles, railway vehicle bodies, etc.

[0076] Thus, according to the method for forming a laminated member of the present invention and the laminated member press-formed by the method, the regions of the joined blank corresponding to the top plate portions of the main body component and the reinforcing component are clamped between a pad die and a punch die. The joined blank is then integrally press-formed into a laminated member. During this process, separation of the first and second plate members does not occur in the regions not clamped between the pad die and the punch die during forming. This prevents gaps from forming between the main body component and the reinforcing component after demolding, thereby avoiding performance degradation of the laminated member and assembly problems.

[0077] E: Boundary point between the top plate portion and the bending ridge portion (of the first plate material L) F: End point (of the first plate material L) L: First plate material L1: Line length (corresponding to the vertical wall portion of the first plate material L in the first form) L2: Line length L (corresponding to the vertical wall portion of the first plate material L in the second form) Ｏ Line length L (from the end of the top plate of the first plate L to the position where the shoulder of the die T2 and the first plate L first come into contact) Ｈ Height (of main body part) L Ｉ Line length (of plate per horizontal unit length) L Ｍ Line length (of the region of the first plate L that is not clamped) (i.e., the total line length of the curved portion and its extension excluding the top plate portion) L ＰLine length O (from the end of the top plate portion of the first plate L to the contact position between the first plate L and the die mold T2) Position (origin) (where the shoulder of the die mold T2 and the first plate L first come into contact) P Second plate P1 Line length (corresponding to the vertical wall portion of the second plate P in the first form) P2 Line length (corresponding to the vertical wall portion of the second plate P in the second form) S Intersection point (extending the straight line portion of the vertical wall portion and flange portion of the first plate L) T1 Punch mold T2 Die mold T3 Pad mold U Intersection point (extending the straight line portion of the top plate portion and vertical wall portion of the first plate L) X Ratio (of the line length corresponding to the vertical wall portion of the second plate P to the line length corresponding to the vertical wall portion of the first plate L) Y Angle z (rising angle of the vertical wall portion relative to the top plate portion of the overlapping member) Horizontal distance θ (from the origin O toward the center of the part) Tilt angle f(z) (of the first plate material L at the contact position between the first plate material L and the die T2) Deflection amount f(z) (of the first plate material L and the second plate material P in the vertical direction at the distance z)

Claims

1. A laminated member is formed by laminating a reinforcing part having a U-shaped or L-shaped cross section, the top plate and vertical wall portions of which are connected to each other at a bending ridge, on the inside of a main body part having a hat-shaped cross section, the top plate and vertical wall portions being connected to each other at a bending ridge, and the laminated member is formed by pressing a joined blank formed by laminating and joining a first metal plate material constituting the main body part and a second metal plate material constituting the reinforcing part in a state in which the regions of the joined blank corresponding to the top plate portions of the main body part and the reinforcing part are clamped. A method for forming a superposed member, characterized in that, in a cross section perpendicular to the bending ridge portion of the superposed member, the line length of the region of the second plate material corresponding to the bending ridge portion and the vertical wall portion of the reinforcing part is set to be equal to or greater than the line length from the end of the region of the first plate material corresponding to the top plate portion of the main body part to the contact position with the shoulder portion of the die mold when the die surface, which is an extension of the flange portion forming surface of the punch mold, comes into contact with the plate material end portion of the first plate material during press forming of the joined blank using a pair of punch molds and die molds.

2. The method for molding a superposed member according to claim 1, characterized in that, in a cross section perpendicular to the bending ridge of the superposed member, when the ratio of the line length of the second plate material corresponding to the vertical wall portion of the reinforcing component to the line length of the region of the first plate material corresponding to the vertical wall portion of the main body component is X, the rise angle Y (degrees) of the vertical wall portion relative to the top plate portion of the superposed member satisfies the following formula (1):

3. When a superposed member is formed by superposing a reinforcing part having a U-shaped or L-shaped cross section, the top plate and vertical wall portions of which are connected to each other at a bending ridge, on the inside of a main body part having a U-shaped cross section, the top plate and vertical wall portions of which are connected to each other at a bending ridge, from a joined blank formed by superposing and joining a first plate material which is a metal plate material constituting the main body part and a second plate material which is a metal plate material constituting the reinforcing part, the joined blank is integrally formed by press-molding the joined blank in a state in which the areas of the joined blank corresponding to the top plate portions of the main body part and the reinforcing part are clamped, A method for forming a superposed member, characterized in that, in a cross section perpendicular to the bending ridge portion of the superposed member, the line length of the region of the second plate material corresponding to the bending ridge portion and the vertical wall portion of the reinforcing part is made equal to or greater than the line length from the end of the region of the first plate material corresponding to the top plate portion of the main body part to the contact position with the shoulder of the die mold when the inclination angle of the first plate material at the position where the shoulder of the die mold contacts the first plate material matches the inclination angle of the vertical wall of the die mold during press forming of the joined blank using a pair of punch molds and die molds.

4. A method for molding a superposed member as described in claim 3, characterized in that, in a cross section perpendicular to the bending ridge of the superposed member, when the ratio of the line length of the region of the second plate material corresponding to the vertical wall portion of the reinforcing component to the line length of the region of the first plate material corresponding to the vertical wall portion of the main body component is X, the rise angle Y (degrees) of the vertical wall portion relative to the top plate portion of the superposed member satisfies the following formula (2). However, 0<Y≦90.

5. A superposed member in which a reinforcing part having a U-shaped or L-shaped cross section, also having a top plate and a vertical wall portion connected to each other at a bending ridge, is superposed on the inside of a main part having a hat-shaped cross section, which has a top plate, a vertical wall portion, and a flange portion connected to each other at a bending ridge, and the superposed member is formed integrally by press molding from a joining blank formed by superposing and joining a first metal plate material constituting the main part and a second metal plate material constituting the reinforcing part, with the regions of the joining blank corresponding to the top plate portions of the main part and the reinforcing part being clamped. A superposed member characterized in that, in a cross section perpendicular to the bending ridge portion of the superposed member, the line length of the region of the second plate material corresponding to the bending ridge portion and the vertical wall portion of the reinforcing part is equal to or greater than the line length from the end of the region of the first plate material corresponding to the top plate portion of the main body part to the contact position with the shoulder portion of the die mold when the die surface, which is an extension of the flange portion forming surface of the punch mold, comes into contact with the plate material end portion of the first plate material during press forming from the joined blank using a punch mold and a die mold.

6. The overlapping member described in claim 5, characterized in that, in a cross section perpendicular to the bending ridge portion of the overlapping member, when the ratio of the line length of the region of the second plate material corresponding to the vertical wall portion of the reinforcing component to the line length of the region of the first plate material corresponding to the vertical wall portion of the main body component is X, the rise angle Y of the vertical wall portion relative to the top plate portion of the overlapping member satisfies the following formula (1).

7. A superposed member in which a reinforcing part having a U-shaped or L-shaped cross section, also having a top plate and a vertical wall connected to each other at a bending ridge, is superposed on the inside of a main part having a U-shaped cross section, the top plate and the vertical wall being connected to each other at a bending ridge, and the superposed member is formed integrally by press molding from a joining blank formed by overlapping and joining a first plate material which is a metal plate material constituting the main part and a second plate material which is a metal plate material constituting the reinforcing part, with the regions of the joining blank corresponding to the top plate parts of the main part and the reinforcing part being clamped. A superposed member characterized in that, in a cross section perpendicular to the bending ridge portion of the superposed member, the line length of the region of the second plate material corresponding to the bending ridge portion and the vertical wall portion of the reinforcing part is equal to or greater than the line length from the end of the region of the first plate material corresponding to the top plate portion of the main body part to the contact position with the shoulder portion of the die mold when the inclination angle of the first plate material at the position where the shoulder portion of the die mold contacts the first plate material matches the inclination angle of the vertical wall portion of the die mold during press molding of the joined blank using a pair of punch molds and die molds.

8. The overlapping member described in claim 7, characterized in that, in a cross section perpendicular to the bending ridge portion of the overlapping member, when the ratio of the line length of the region of the second plate material corresponding to the vertical wall portion of the reinforcing component to the line length of the region of the first plate material corresponding to the vertical wall portion of the main body component is X, the rise angle Y (degrees) of the vertical wall portion relative to the top plate portion of the overlapping member satisfies the following formula (2). However, 0<Y≦90.

9. A method for manufacturing an automobile part including a superposed member according to any one of claims 5 to 8, comprising the step of molding the superposed member using the method for molding a superposed member according to any one of claims 1 to 4.

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