Joining member, press forming die, joining method and method of manufacturing the joining member

Abstract

A joining technology is provided that has excellent surface quality without causing quality defects such as cracks. The joining member comprises a first member having a protrusion and a second member having a hole, which are joined by overlapping each other in the direction of plate thickness. The protrusion has a length greater than that of the hole before joining, and the protrusion has a narrower width than that of the hole and is formed by connecting to another part of the first member and extending to bend in the direction of the second member, a convex curved portion formed by connecting to the convex curved portion and extending to bend in the opposite direction of the convex curved portion, and a concave curved portion inserted into the hole, and a tapered portion connected to the concave curved portion and extended to have the widest width at the tip and a width wider than that of the hole, and a caulking portion that caulks to push and widen the hole.

Description

Technology Field

[0001] The present invention relates to a joining member, a press molding die, a joining method, and a method for manufacturing a joining member. Background Technology

[0002] From the perspective of protecting occupants in a vehicle body, improved crash safety is required. On the other hand, it is also important to lighten the vehicle body to improve fuel efficiency in order to reduce carbon dioxide emissions. To achieve both crash safety performance and body weight reduction, the application of high-strength materials to the skeletal components of the vehicle body is increasing year by year. For example, pillar components such as front pillars and center pillars, which form the cabin of the vehicle body, are important skeletal components for protecting occupants inside the cabin during a collision. Therefore, pillar components are required to withstand collision loads, and high-strength steel plates with a tensile strength grade of 1470 MPa or higher are also being applied.

[0003] FIG. 17 illustrates an example of a frame part of a vehicle. The press-formed part (100) consists of a main body part (1B) and a reinforcing part (2B). In the example of FIG. 17, the main body part (1B) has a hat-shaped cross-section and consists of a top plate part (13), a longitudinal wall part (14), a flange part (15), and a ridge part connecting them. The reinforcing part (2B) is placed on the inside of the main body part (1B) and, in the example of FIG. 17, has a U-shaped (groove-shaped) cross-section and consists of a top plate part (22), a longitudinal wall part (23), and a ridge part connecting them. The main body part (1B) and the reinforcing part (2B) are joined to each other by resistance spot welding, so that a joint part (111) is placed on the top plate part (13, 22) and the longitudinal wall part (14, 23).

[0004] Welding is a typical method for joining parts together. However, when joining dissimilar materials such as steel plates and aluminum alloy plates, direct welding is difficult due to differences in melting points or thermal conductivity. In addition, there is a risk that the surface quality of the product may deteriorate due to spatter generated during welding.

[0005] In addition to welding, mechanical joining is generally known as a method for joining thin sheets. For example, Patent Document 1 discloses a self-piercing rivet that joins overlapping members to be joined by using a rivet (1) having a hollow shaft portion (4) having a central hole (3) that opens at the tip. The technology of Patent Document 1 involves driving the rivet by heating a heating range on at least one side of the members to be joined until the members to be joined reach a predetermined temperature, centered around the rivet driving point.

[0006] In addition, Patent Document 2 discloses a technique in which a plate-shaped upper back panel and a side panel, of which at least a portion overlaps in the plate thickness direction of the upper back panel, are joined by mechanical clinch joining from the upper back panel side at a plurality of clinch portions. In addition, Patent Document 3 discloses a technique in which a plate-shaped fastening material having small holes is overlapped with a fastening material having large holes, a burring punch is pressed into the small holes, and the members are fastened by caulking through the additionally pressed burring.

[0007] In addition, Patent Document 4 discloses a method of performing welding by embedding resistance spot welding guns in an opposing arrangement inside a mold and simultaneously forming overlapping blanks and applying current at the bottom dead center. In addition, Non-Patent Document 1 describes a method of intentionally causing buckling on the longitudinal wall of a main body part so that the buckling part functions to lock an inner reinforcing part, thereby preserving and maintaining the reinforcing part. Prior art literature

[0008] Japanese Published Patent Application No. 2006-007266, Japanese Published Patent Application No. 2019-084570, Japanese Published Patent Application No. 2020-029876, Japanese Published Patent Application No. Hei 01-186227

[0009] Combined process of hot stamping and mechanical joining for producing ultra-high strength steel patchwork components, Journal of Manufacturing Processes, 59(2020), pp. 444-455 The problem to be solved

[0010] However, each of the above conventional technologies has the following problems that must be solved.

[0011] That is, in the method disclosed in Patent Document 1, the fracture of the joint during forming is a problem. When two blanks are overlapped and joined, the difference in line length between the inner and outer sides of the bend causes misalignment between the blanks.

[0012] In the method disclosed in Patent Document 2, although the problem of misalignment between blanks is resolved, there is a problem that the two parts become separated when detached from the integrally formed mold, making it impossible to weld them in the next process. To prevent this, joining is performed simultaneously with forming in the mold, or at least, temporary fastening is required to maintain an integral state where the main body part and the reinforcing part do not become separated until they are returned to the subsequent welding process.

[0013] The mechanical joining disclosed in Patent Document 3 causes significant deformation of the material, so when applied to materials lacking ductility, such as high-strength steel plates, there is a concern that the material may crack. In addition, the method described in Patent Document 4 requires complex equipment, which raises concerns about excessive investment in equipment.

[0014] The technology described in Non-Patent Literature 1 is carried out using a hot press that heats and forms the material. In this method, the material becomes soft and undergoes localized deformation. However, this technology is difficult to apply to high-strength steel sheets formed by a cold press to maintain strength.

[0015] The present invention has been made to solve the above problem, and its purpose is to provide a joining technology that is economical and has excellent surface quality, without causing quality defects such as cracks, by using materials with insufficient ductility, such as high-strength steel plates. means of solving the problem

[0016] The gist of the present invention, which advantageously solves the above problem, is as follows.

[0017] [1] A joining member having a first member having a protrusion and a second member having a hole, joined together in the direction of plate thickness, wherein the length of the protrusion before joining is longer than that of the hole, and the protrusion has a narrower width than that of the hole and is formed by extending and bending in the direction of the second member, a convex bending part formed by extending and connecting to another part of the first member and bending in the opposite direction of the convex bending part, and a concave bending part inserted into the hole, and a tapered shape formed by extending and connecting to the concave bending part and widening toward the tip, and the tip having a wider width than that of the hole, and a caulking part that pushes and widens the hole.

[0018] [2] In the above [1], the first member has the protrusion on the flat portion, and the second member has the hole on the flat portion, and the first member and the second member are integrally formed by overlapping each other in the plate thickness direction, and have a C-shaped cross section or a hat-shaped cross section having at least a top plate portion and a side wall portion, and the first member and the second member are joined by press forming at a location corresponding to the flat portion.

[0019] [3] In the above [2], the flat portion is a joining member in which at least one of the top plate portion and the side wall portion is a joining member.

[0020] [4] A press forming die for press forming a joining member described in [2] or [3] above, wherein the first member and the second member overlap each other and integrally form a member having a C-shaped cross section or a hat-shaped cross section having at least a top plate portion and a side wall portion, and the two blanks are joined at a location corresponding to the flat portion of the member, and the joining die has a convex-shaped indentation portion formed on one of a pair of opposing dies and a concave-shaped first relief portion adjacent to the indentation portion, and a concave-shaped second relief portion formed on the other die and into which the convex-shaped indentation portion is inserted.

[0021] [5] In the above [4], the opposing pair of molds is a press forming mold, which is a pad and a punch.

[0022] [6] In the above [4], the pair of opposing molds are press forming molds, which are a die and a punch.

[0023] [7] A joining method in which a first member having a protrusion and a second member having a hole are joined by overlapping them in the direction of plate thickness, wherein the length of the protrusion before joining is made longer than the hole, and the first part of the protrusion, which has a narrower width than the hole, is bent in the direction of the second member to form a convex curve, and the second part of the protrusion, which has a narrower width than the hole, is bent in the opposite direction of the convex curve to form a concave curve, and the second part of the protrusion, which has a narrower width than the hole, is bent to form a concave curve while being extended in the direction opposite to the convex curve to form a concave curve, and a tapered portion that is widened toward the tip and has a wider width than the hole is formed by caulking to push the hole.

[0024] [8] In the above [7], the first member and the second member are made of metal plates and formed by press forming, and the first member and the second member are formed by press forming, and the first member and the second member have a C-shaped cross section consisting of a top plate and a side wall, or a hat-shaped cross section consisting of a top plate, a side wall, and a flange, and the method of joining the members by press forming includes a blank processing process of processing at least the outer circumference of the metal plate to obtain a first blank and a second blank, a forming process of forming the first blank and the second blank into a target shape by press forming each to obtain the first member and the second member, and a joining process of joining the first member and the second member by the method described in [7].

[0025] [9] In the above [8], the joining method is to join the first member and the second member to at least one of the top plate and the flange portion.

[0026]

[10] In the above [7], the first member has the protrusion on the flat portion, and the second member has the hole portion on the flat portion, and the first member and the second member are overlapped in the plate thickness direction to form a member having a U-shaped cross section consisting of a top plate portion and a vertical wall portion, or a hat-shaped cross section consisting of a top plate portion, a vertical wall portion, and a flange portion, and a method of joining the first member and the second member by press forming at a location corresponding to the flat portion, wherein a press forming die is provided having a convex-shaped press-fit portion formed on one of a pair of opposing dies, a concave-shaped first relief portion adjacent to the press-fit portion, and a concave-shaped second relief portion formed on the other die into which the convex-shaped press-fit portion is inserted, and a joining portion is provided using a press forming die having a convex-shaped press-fit portion formed on one of the pair of opposing dies and a concave-shaped second relief portion into which the convex-shaped press-fit portion is inserted, wherein the protrusion of the first member is extended to connect with another part of the first member, and the portion having a narrower width than the hole portion is joined by the hole portion and the second A joining method comprising a joining process in which a caulking portion, having a tapered shape among the protrusions and having a wider width at its tip than the hole portion, is brought into contact with the longitudinal edge of the hole portion to erect the caulking portion and position the tip of the caulking portion within the first relief portion, and caulking the caulking portion so as to push the hole portion in the width direction to widen it, and a forming process in which another portion is formed into a target shape.

[0027]

[11] In the above

[10] , the flat portion is at least one of the top plate portion and the side wall portion, and the joining method is

[0028]

[12] In the above

[10] or

[11] , the opposing pair of molds are a pad and a punch, and the pad is lowered to join the overlapping members by pressing them with the punch.

[0029]

[13] In the above

[10] or

[11] , the pair of opposing molds are a die and a punch, and the die is lowered to join the overlapping members by pressing them together with the punch.

[0030]

[14] A method for manufacturing a bonded member, comprising a process of overlapping and bonding the first member and the second member using the bonding method described in any one of [7] to

[13] above. Effects of the invention

[0031] According to the present invention, even materials lacking ductility, such as high-strength steel plates, can be stably joined without causing quality defects such as cracking. Since it is a mechanical joining technology, it does not degrade surface quality like welding. Brief explanation of the drawing

[0032] FIG. 1 is a schematic perspective view showing a joint portion of a joining member according to one embodiment of the present invention. FIG. 2 is a side view of the joint portion according to the above embodiment. FIG. 3 is a top view of the joint portion according to the above embodiment. FIG. 4 is a schematic perspective view of a joint portion for explaining a joining method according to the above embodiment. FIG. 5 is a cross-sectional view taken from XX of FIG. 4, showing a cross-sectional view in the width direction of the joint portion to explain the joining method according to the above embodiment. FIG. 6 is a top view of the joint portion of the first member according to the above embodiment before joining. FIG. 7 is a top view of the joint portion of the second member according to the above embodiment. FIG. 8 is a schematic top view showing the positional relationship between the protrusion and the hole according to the above embodiment. FIG. 9 is a schematic perspective view showing a joint portion of a joining member according to another embodiment of the present invention. FIG. 10 is a schematic perspective view showing a press-formed member as an example of a joining member according to the above embodiment. FIG. 11 is a schematic cross-sectional view showing the configuration of a mold and the movement of a mold for forming a press-formed member according to the above embodiment. FIG. 12 is a schematic perspective view showing the behavior of a blank of a joint during press forming of a press-formed member according to the above embodiment. FIG. 13 is a schematic perspective view showing another example of a press-formed member. FIG. 14 is a schematic perspective view showing one flow of the manufacturing process of the press-formed member. FIG. 15 is a schematic perspective view showing another flow of the manufacturing process of the press-formed member. FIG. 16 is a schematic perspective view showing another example of a press-formed member. FIG. 17 is a schematic perspective view showing a conventional press-formed member. Specific details for implementing the invention

[0033] (Form for carrying out the invention)

[0034] Embodiments of the present invention will be described in detail below. Furthermore, each drawing is schematic and may differ from the actual product. Also, the following embodiments are intended to illustrate components or methods for embodying the technical concept of the present invention and are not intended to limit the configuration to the following. That is, the technical concept of the present invention may be modified in various ways within the technical scope described in the claims.

[0035] <First Embodiment>

[0036] In this embodiment, the subject is a member formed by joining two plate-shaped members, and the following description focuses on the joint. Accordingly, the members to be joined may be flat plate-shaped members or structural members formed to have a three-dimensional shape. The shape is not specifically limited.

[0037] (Joining member)

[0038] FIGS. 1 to 3 show an example of a joint portion of a joining member. FIG. 1 is a schematic perspective view, FIG. 2 is a schematic side view, and FIG. 3 is a top view. In the drawings, symbol 1 represents a first member, symbol 2 represents a second member. Symbol 12 represents a protrusion formed on the first member (1), and symbol 21 represents a hole formed on the second member (2). FIG. 6 is a top view of the first member (1) before joining, FIG. 7 is a top view of the second member (2), and FIG. 8 is a top view showing the positional relationship between the protrusion (12) and the hole (21) before joining when the first member (1) and the second member (2) are overlapped with each other. The joint portion (110) of the joining member according to the present embodiment is a portion in which the first member (1) and the second member (2) are overlapped and joined in the plate thickness direction. In addition, as illustrated in FIG. 6, the protrusion (12) has a nearly rectangular shape before joining. Among the protrusions (12), the side that connects with another part of the first member is designated as the connecting part (13). The direction in which the protrusion (12) extends from the connecting part (13) is defined as the length direction (L), and the direction within the plane of the protrusion (12) and perpendicular to the length direction (L) is defined as the width direction (W). The hole portion (21) of the second member (2) is rectangular, and the length direction (L) and width direction (W) are defined in the same way as the protrusion (12) when overlapping with the first member (1). In this embodiment, the protrusion (12) is formed within the plane of the first member (1) and is surrounded by the frame portion (11) of another part. Additionally, the hole portion (21) is surrounded by the frame portion (22) of the second member (2) that constitutes each side thereof.

[0039] As shown in FIG. 8, the length (L1) of the protrusion (12) before joining is longer than the length (L2) of the hole (21). Additionally, in the joined state, the protrusion (12) has a convex curve (12A), a concave curve (12B), and a caulking portion (12C). The convex curve (12A) is formed by extending it in connection with, for example, the frame portion (11) and the connection portion (13), and bending it in the direction of the second member while contacting one edge of the length direction (L) of the hole (21). The concave curve (12B) is formed by extending it in connection with the convex curve (12A) and bending it in the opposite direction to the convex curve (12A), and is inserted into the hole (21). Additionally, the convex curve (12A) and the concave curve (12B) may be continuous curved surfaces, or a flat portion may be inserted between them. Width (W) of the convex curve (12A) 1A ) and the width (W) of the concave curve (12B) 1B All of them are narrower than the width (W2) of the hole portion (21). The caulking portion (12C) is connected to the concave curve portion (12B) and extends, and widens toward the leading edge in the longitudinal direction (L), and the width of the leading edge (W 1C ) has a tapered shape with a width wider than the width (W2) of the hole portion. The caulking portion (12C) contacts the other edge in the length direction (L) of the hole portion (21) and caulks both edges in the width direction (W) of the hole portion (21) to push and widen them, thereby joining the first member (1) and the second member (2). The length (L1) of the protrusion (12) is approximately equal to the line length along the curved surface from the connecting portion (13) of the protrusion (12) after joining to the tip of the caulking portion (12C).

[0040] (Joining method)

[0041] A joining method according to the first embodiment will be described with reference to FIGS. 4 and 5. FIGS. 4 and 5 are a perspective view and a cross-sectional view, respectively, of the center of the width direction XX, showing (a) the state before joining and (c) the state until joining is completed, with the first member (1) and the second member (2) overlapping each other. In the blank state, the first member (1) is cut, for example, as shown in FIG. 6, and a protrusion (12) surrounded by a frame part (11) is processed. In addition, in the blank state, the second member (2) is processed with a hole part (21) surrounded by a frame part (22) as shown in FIG. 7. The processing method at this time may be any of the following: shear processing, laser processing, electrical discharge processing, etc., and is not limited.

[0042] In the example of FIG. 6, the protrusion (12) extends from the connection portion (13) in the state prior to joining and has a width (W) narrower than the width (W2) of the hole portion (21). 1A =W 1B It has a parallel section (12D) having ). In addition, the protrusion (12) extends from the parallel section (12D), widens toward the tip, and the width of the tip (W) 1C ) has a caulking portion (12C) having a tapered shape with a width wider than the width (W2) of the hole portion.

[0043] In the joining method according to the present embodiment, first, as shown in FIGS. 4(a) and FIGS. 5(a), the first member (1) and the second member (2) are overlapped at a predetermined position. As illustrated in FIG. 8, it is preferable to arrange the protrusion (12) and the hole (21). The edge in the width direction of the parallel portion (12D) of the protrusion (12) is positioned so that it is inside the edge in the width direction of the hole (21), and the tip of the caulking portion (12C) is positioned so that it is outside the hole (21). In addition, it is preferable to align the center line in the width direction of the protrusion (12) with the center line in the width direction of the hole (21). To improve the positioning precision of the overlapped members, a positioning pin or the like may be used.

[0044] Next, as shown in FIGS. 4(b) and FIGS. 5(b), the parallel portion (12D) is pressed in the direction of the second member. Among the parallel portion (12D), the first portion extending from the connection portion (13) with another part of the first member (1) is bent in the direction of the second member to form a convex bend portion (12A). At this time, it is preferable to leave a predetermined amount of the connection portion (13) side of the parallel portion (12D) from one edge in the longitudinal direction of the hole portion (21), so that the convex bend portion (12A) bends while contacting one edge thereof.

[0045] At the same time, the back surface of the protrusion (12) and the other edge in the longitudinal direction of the hole (21) come into contact, and the caulking portion (12C) slides and is inserted into the hole (21) (Figs. 4(b) and 5(b)). At this time, the remaining second part of the parallel portion (12D) located between the convex curved portion (12A) and the caulking portion (12C) bends in the opposite direction to the convex curved portion to form a concave curved portion (12B) that is inserted into the hole (21). Then, the caulking portion (12C) is erected and becomes tilted at an angle with respect to the surface of the second member (2) in the longitudinal direction.

[0046] Additionally, when the parallel portion (12D), that is, the concave curved portion (12B), is continuously pressed, both ends of the caulking portion (12C) in the width direction come into contact with both edges of the hole portion (21) in the width direction. As shown in FIGS. 4(c) and FIGS. 5(c), the pressing of the parallel portion (12D) is completed at the point where the caulking portion (12C) is caulked to push and widen the hole portion (21) with a predetermined load and stroke. Accordingly, the first member (1) and the second member (2) are joined.

[0047] <Second Embodiment>

[0048] The present embodiment is a press forming method using the so-called patchwork method, in which two flat blanks (members) are integrally formed with a single mold, and a press forming mold for realizing the same. The difference from conventional press forming is that the blanks are set in the mold while unjoined, and joining is performed simultaneously with forming.

[0049] The press-formed member targeted in this embodiment is formed by overlapping members having at least a top plate portion and a side wall portion. An example of a press-formed member (100) according to this embodiment is shown in a schematic perspective view in FIG. 10. As shown in FIG. 10, a press-formed member (100) is described as an example in which a main body part (1A) having a hat-shaped cross section and a reinforcing part (2A) having a C-shaped (groove-shaped) cross section on the inside thereof are overlapped and joined at the center of the width direction of the top plate portion (113). The main body part (1A) consists of a top plate portion (113), a side wall portion (114), a flange portion (115), and a ridge portion connecting them. The reinforcing part (2A) consists of a top plate portion (122), a side wall portion (123), and a ridge portion connecting them. A mechanical joint portion (110) is disposed on the top plate portions (113, 122).

[0050] FIG. 11 is a schematic cross-sectional view showing the configuration of a press forming die suitable for use in the press forming method according to the present embodiment and the movement of the die. The upper die (3) is composed of a die (31) and a pad (32). The pad (32) is connected to a pressure device acting as an elastic support means, such as a gas cushion, a hydraulic device, or a spring, and is configured to be a mechanism capable of loading the top plate portion downward. The lower die (4) is a punch (41). Additionally, the top plate portions of the pad (32) and the punch (41) have a joining portion for joining two plates; however, in order to first explain the forming of the entire part, the explanation regarding joining is omitted here and will be explained in detail later.

[0051] (Press forming method)

[0052] First, as shown in FIG. 11(a), a first blank (1A) that serves as a main body part and a second blank (2A) that serves as a reinforcing part are overlapped and set on a punch (41). The first blank (1A) and the second blank (2A) are aligned using conventional methods such as pins and holes so that the joint of each blank fits into the correct position of each mold.

[0053] Next, as shown in FIG. 11(b), the die (31) and pad (32) of the upper die (3) are lowered, and the portion corresponding to the top plate (113, 122) of the blank (1, 2) is pushed downward by the pad (32). Accordingly, the top plate (113, 122) is pressed between the pad (32) and the punch (41) and retained.

[0054] In this state, as shown in FIG. 11(c), the die (31) of the upper mold (3) is further lowered to simultaneously bend and form two blanks (1, 2) while forming the longitudinal wall portion (114, 123) and the flange portion (115), thereby forming the target shape.

[0055] (Mechanical joining)

[0056] Next, the joining of two blanks will be explained.

[0057] In this embodiment, blanks are mechanically joined by the movement of the mold during press forming. In this embodiment, the explanation focuses on the joining portion (110) of the top plate portion (113, 122).

[0058] FIG. 4 is a schematic perspective view showing the behavior of two blanks (1A, 2A) during press forming in the joint portion (110). FIG. 6 is a top view of the protrusion (12) formed on the first blank (1A) before joining. FIG. 7 is a top view of the hole portion (21) formed on the second blank (2A). FIG. 8 is a top view showing the positional relationship between the protrusion (12) and the hole portion (21) when the first blank (1A) and the second blank (2A) are overlapped. In addition, as illustrated in FIG. 6, the shape of the protrusion (12) before joining is nearly rectangular, and the side connecting to another part of the first blank (1A) is the connecting portion (13). The direction in which the protrusion (12) extends from the connection part (13) is defined as the length direction (L), and the direction within the plane of the protrusion (12) and perpendicular to the length direction (L) is defined as the width direction (W). The hole portion (21) of the second blank (2A) is made rectangular, and the length direction (L) and width direction (W) are defined in the same way as the protrusion (12) when they overlap each other. The processing of the protrusion (12) to the first blank (1A) or the processing of the rectangular hole portion (21) to the second blank (2A) may be any of the following, such as shear processing, laser processing, or electrical discharge processing, and is not limited. The alignment of the protrusion (12) and the hole portion (21) may be the same as in the first embodiment.

[0059] FIG. 12 is a schematic enlarged cross-sectional view showing the behavior of the mold (3, 4) and blank (1A, 2A) near the joint (110) shown in the cross-section at XX of FIG. 4. The joint of the pad (32) that becomes the upper mold (3) has a convex-shaped press-in portion (32A) and a concave-shaped first relief portion (32B) adjacent to the press-in portion (32A). The joint of the punch (41) that becomes the lower mold (4) has a concave-shaped second relief portion (41A).

[0060] After setting the blanks (1, 2) at the above-mentioned positions, the pad (32) is lowered so that the press-fit portion (32A) of the pad (32) comes into contact with the parallel portion (12D) of the protrusion (12), as shown in FIG. 12(a). Then, as the pad (32) is lowered, the press-fit portion (32A) is inserted into the hole portion (21), as shown in FIG. 12(b). Then, the parallel portion (12D) of the protrusion (12) is bent and deformed. Among the parallel portions (12D), the first portion extending from the connection portion (13) with another part of the first blank (1A) is bent in the direction of the second blank (2A) to form a convex curved portion (12A). At this time, it is preferable to leave a predetermined amount of the connecting portion (13) side of the parallel portion (12D) from one edge in the longitudinal direction of the hole portion (21), so that the convex curved portion (12A) bends while contacting that edge.

[0061] At this time, the caulking portion (12C) is erected by the contact between the back surface of the protrusion (12) of the first blank and the other end edge in the longitudinal direction of the hole portion (21) of the second blank. At this time, the remaining second portion of the parallel portion (12D) located between the convex curve portion (12A) and the caulking portion (12C) is bent in the opposite direction to the convex curve portion to form a concave curve portion (12B) that is inserted into the hole portion (21). Additionally, the convex curve portion (12A) and the concave curve portion (12B) may be continuous curved surfaces, or a flat portion may be inserted between them. The caulking portion (12C) is in a state where it has an angle with respect to the second blank. Here, when the protrusion (12) is pressed in, the second relief portion (41A) of the punch (41) is present so that contact between the concave curve portion (12B) of the protrusion (12) and the lower die (4) can be avoided. Additionally, when the caulking part (12C) is erected, the first relief part (32B) on the pad (32) can be avoided by having the tip of the caulking part (12C) and the upper mold (3).

[0062] Additionally, as the pad (32) is continuously pressed in, a caulking portion (12C) is inserted into the hole portion (21) as shown in FIG. 12(c). At the point where the width of the caulking portion (12C) is greater than the width of the hole portion (21) and the portion is inserted into the hole portion (21), the caulking portion (12C) is caulked to push the hole portion (21) in the width direction. Accordingly, the two members (1, 2) are joined. At the point in FIG. 12(c), the two blanks are pressed and maintained by the pad (32) and the punch (41), and while maintaining this state, the end wall portion (114, 123) and the flange portion (115) are formed by the die (31).

[0063] In the above example, an example of a mold is shown having a press-fit part (32A) and a first relief part (32B) on the pad (32) of the upper mold (3), and a second relief part (41A) on the lower mold (4), but the press-fit part and the first relief part may be on the lower mold (4), and the second relief part may be on the upper mold (3).

[0064] Additionally, although the above description was given as an example having a joining portion (110) on the top plate portion (113, 122), as shown in FIG. 13, the joining portion (110) may also be on the side wall portion (114, 123). In this case, as shown in FIG. 11(c), at the bottom dead center of the press, the die (31) and the punch (41) join two blanks at the stage of pressing them together. For example, it is preferable to employ a cam mechanism in which the pressing portion of the die (31) moves in the direction perpendicular to the plane of the side wall portion (114, 123).

[0065] In the case of a subsequent welding process, the joint (110) may have a bonding strength sufficient to prevent the parts from separating when the overlapping blanks are integrally formed. If it is predicted that the bonding strength is insufficient with a predetermined number of joints (110), the number of joints (110) may be increased.

[0066] <Third Embodiment>

[0067] A third embodiment of the present invention is a method for joining press-formed members by mechanically joining members having a U-shaped cross section formed by a top plate portion and a side wall portion, or a hat-shaped cross section formed by a top plate portion, a side wall portion, and a flange portion. For example, as shown in FIG. 10, a press-formed member (100) is described as an example in which a first member (1) having a hat-shaped cross section and a second member (2) having a U-shaped cross section on its inner side overlap each other and are joined at the center of the top plate portions (113, 122).

[0068] FIG. 14 is a schematic perspective view showing the flow of a manufacturing process for a press-formed member (100) according to the above embodiment. Here, the blank that becomes the first member (1) is designated as the first blank (1A), and the blank that becomes the second member (2) is designated as the second blank (2A). First, in the blank processing process, the outer circumference of each blank (1A, 2A) is processed into a blank shape (Fig. 14(a), (b)). In addition, a protrusion (12) is formed at a location corresponding to the joint (110) of the first blank (1A) (Fig. 14(a)). Then, a rectangular hole (21) is formed at a location corresponding to the joint (110) of the second blank (2A) (Fig. 14(b)). Examples of the protrusion (12) and the hole (21) are shown as top views in FIG. 6 and FIG. 7, respectively. In addition, as illustrated in FIG. 6, the protrusion (12) has a nearly rectangular shape before joining, and the side connecting to another part of the first blank (1A) is defined as the connecting part (13). The direction in which the protrusion (12) extends from the connecting part (13) is defined as the length direction (L), and the direction within the plane of the protrusion (12) and perpendicular to the length direction (L) is defined as the width direction (W). The hole part (21) of the second blank (2A) is rectangular, and the length direction (L) and width direction (W) are defined in the same way as the protrusion (12) when they overlap each other. The length of the protrusion (12) is longer than the length of the hole part. In addition, the width varies depending on the length position, and it has a parallel part (12D) that is narrower than the hole part (21), and a tapered caulking part (12C) that has the widest width at the tip and is wider than the hole part. Here, the processing of the protrusion (12) into the first blank (1A) or the processing of the rectangular hole (21) into the second blank (2A) in the blank processing process is not limited to shear processing, laser processing, electrical discharge processing, etc.

[0069] Next, in the forming process, the first blank (1A) is formed by press forming into a hat-shaped cross-section part shape consisting of a top plate (113), a side wall (114), and a flange (115) to obtain the first member (1) (Fig. 14(c)). Then, the second blank (2A) is formed into a C-shaped cross-section part shape consisting of a top plate (122) and a side wall (123) to obtain the second member (2) (Fig. 14(d)). Here, bending or drawing, etc., can be applied as the press forming method, and there are no particular limitations.

[0070] In the subsequent joining process, first, the first member (1) and the second member (2) are overlapped in the plate thickness direction. FIG. 8 is a top view showing the positional relationship between the protrusion (12) and the hole (21) when the first member (1) and the second member (2) are overlapped. It is preferable to arrange the protrusion (12) and the hole (21) as shown in FIG. 8. The edge in the width direction of the parallel portion (12D) of the protrusion (12) is positioned so that it is inside the edge in the width direction of the hole (21), and the tip of the caulking portion (12C) is positioned so that it is outside the hole (21). In addition, it is preferable to align the center line in the width direction of the protrusion (12) with the center line in the width direction of the hole (21). As such, since precision in the relative position of the two members is required, it is preferable to set the members by applying a positioning pin or the like.

[0071] After setting the member, the joint (110) is joined by pressing it with a mold. Figures 4(a) to 4(c) respectively show perspective views of the state from the unjoined state to the completion of joining. Figure 12 shows a simplified cross-sectional view of the cross-section seen from XX, the center of the width direction of the joint. The upper mold (3) has a convex-shaped press-in portion (32A) and a concave-shaped first relief portion (32B) adjacent to the press-in portion (32A). The lower mold (4) has a concave-shaped second relief portion (41A). The upper mold (3) is lowered so that the press-in portion (32A) of the pad (32) comes into contact with the parallel portion (12D) of the protrusion (12), as shown in Figure 12(a). After that, as shown in FIG. 12(b), the pad (32) descends, and the press-fit portion (32A) is inserted into the hole portion (21). Then, the parallel portion (12D) of the protrusion (12) is bent and deformed. Among the parallel portion (12D), the first portion extending from the connection portion (13) with another part of the first member (1) is bent in the direction of the second member (2) to form a convex bend portion (12A). At this time, it is preferable to leave a predetermined amount of the connection portion (13) side of the parallel portion (12D) from one edge in the longitudinal direction of the hole portion (21), so that the convex bend portion (12A) bends while contacting one edge thereof.

[0072] At this time, the caulking portion (12C) is erected by the contact between the back surface of the protrusion (12) of the first member (1) and the other end edge in the longitudinal direction of the hole portion (21) of the second member (2). At this time, the remaining second portion of the parallel portion (12D) located between the convex curve portion (12A) and the caulking portion (12C) is bent in the opposite direction to the convex curve portion (12A) to form a concave curve portion (12B) that is inserted into the hole portion (21). Additionally, the convex curve portion (12A) and the concave curve portion (12B) may be continuous curved surfaces, or a flat portion may be inserted between them. The caulking portion (12C) is in a state where it has an angle with respect to the second blank. Here, when the protrusion (12) is pressed in, the second relief portion (41A) on the punch (41) prevents contact between the concave curved portion (12B) of the protrusion (12) and the lower die (4). Additionally, when the caulking portion (12C) is erected, the first relief portion (32B) on the pad (32) prevents contact between the tip of the caulking portion (12C) and the upper die (3).

[0073] Additionally, as the pad (32) is continuously pressed in, a caulking portion (12C) is inserted into the hole portion (21) as shown in FIG. 12(c). When the portion of the caulking portion (12C) that is greater than the width of the hole portion (21) is inserted into the hole portion (21), the caulking portion (12C) caulks to push the hole portion (21) in the width direction. Accordingly, the two members (1, 2) are joined.

[0074] (Fourth embodiment)

[0075] As described in the third embodiment, in the joining process, it is necessary to align the protrusion (12) of the first member (1) and the hole (21) of the second member (2) with high precision. If pre-processing is performed in the blanking process, there is a possibility that the position of the protrusion (12) or the hole (21) may change during the forming process. In the fourth embodiment of the present invention, the protrusion (12) and the hole (21) are formed on the part after press forming.

[0076] FIG. 15 is a schematic perspective view showing the flow of a manufacturing process for a press-formed member (100) according to a second embodiment. In the blank processing process, the outer circumference of the first blank (1A) and the second blank (2A) is processed into a blank shape (Fig. 15(a), (b)). Next, in the forming process, the first blank (1A) is formed by press forming into a part shape with a hat-shaped cross section consisting of a top plate portion (113), a side wall portion (114), and a flange portion (115) to obtain the first member (1) (Fig. 15(c)). Then, the second blank (2A) is formed into a part shape with a U-shaped cross section consisting of a top plate portion (122) and a side wall portion (123) to obtain the second member (2) (Fig. 15(d)). Next, in the example of FIG. 7, a protrusion (12) is formed on the top plate (113) of the first member (1) (Fig. 15(e)). Then, a hole (21) is formed on the top plate (122) of the second member (2) (Fig. 15(f)). The joining process is mechanically joined by aligning the protrusion (12) and the hole (21) in the same way as in the third embodiment. In the fourth embodiment, since the protrusion (12) and the hole (21) are formed after molding each member, the two members can be set with high positional precision during joining.

[0077] (Fifth embodiment)

[0078] The examples described above were all press-formed members in which a second member (2) with a U-shaped cross section was placed and joined to the inside of a first member (1) with a hat-shaped cross section. Meanwhile, as shown in FIG. 16, the press-formed member may also be made according to a fifth embodiment in which two members (1, 2) with hat-shaped cross sections are joined to each other by flange portions (115, 124).

[0079] (6th embodiment)

[0080] Additionally, the joining method described above assumes joining at any point inside the first member (1) and the second member (2), but as shown in FIG. 9, joining with the second member (2) at the end of the first member (1) is also acceptable. In that case, the protrusion (12) is processed to protrude from the end of the first member (1).

[0081] (Other conditions)

[0082] The present invention is intended for application as a temporary joining method for connecting and fixing members together prior to the final welding process of the parts. Accordingly, it is desirable for the parts to possess sufficient bonding strength to prevent separation after the temporary joining. If the bonding strength is insufficient, the number of joints may be increased.

[0083] In addition, in the above example, the protrusion is made nearly rectangular, and the hole is made rectangular. Regarding the relative dimensional relationship between the protrusion and the hole, the length (L1) of the protrusion is greater than the length (L2) of the hole, and the width (W) of the convex and concave curves 1A , W 1B ) is narrower than the width (W2) of the hole portion, and the maximum width (W) of the caulking portion 1C The protrusion (L1) needs to be wider than the width (W2) of the hole. The length of the protrusion (L1) is approximately equal to the line length along the curved surface from the connection point of the protrusion after joining to the tip of the caulking part. As long as these relative dimensional relationships are satisfied, there are no restrictions on the length, width, shape, or ratio of the protrusion and the hole. If the protrusion deforms due to the self-weight of the part or external load after joining, causing a gap between the parts, it is preferable to make the protrusion and the hole wider to make deformation difficult. For example, this can be applied to steel plates with a tensile strength of 270 to 1800 MPa and a plate thickness of 0.7 to 2.3 mm. The dimensions of the protrusion are length (L1) × maximum width (W 1CThe dimensions of the hole portion can be set to 10–50 mm × 5–50 mm in length (L2) × width (W2) of 7–35 mm × 5–50 mm. Additionally, the opening angle (φ) of the taper of the caulking portion can be 0.5–10°. It is preferable that the angle (θ) formed by the surface of the caulking portion and the second member be 30° or more and less than 90°.

[0084] <Method for manufacturing a joining member>

[0085] According to the above embodiment, the joining method may include a joining process for joining a first member (1) and a second member (2), and may be a method for manufacturing a joined member (100) in which a first member (1) and a second member (2) are joined, for example, having a U-shaped cross section or a hat-shaped cross section. The method for manufacturing the joined member (100) may include a welding process. Additionally, a process of applying an adhesive before the joining process may be included. In that case, the mechanical joining according to the above embodiment may be used for curing the joining of the members by the adhesive.

[0086] (Industrial Applicability)

[0087] According to the present invention, a joining member and a joining method are provided, wherein bending deformation is imparted to a member and additionally caulking is utilized at the edge portion. Compared to conventional joining methods that impart large plastic deformation, damage to the member is minimal. Accordingly, even with materials lacking ductility, such as high-strength steel plates, stable joining is possible without causing quality defects such as cracking. Furthermore, since parts formed by, for example, press forming are obtained in a tack-joined state, welding is facilitated in the subsequent welding process, thereby contributing to cost reduction. Explanation of the symbols

[0088] 100 : Joining member (press-formed member) 110 : (Mechanical) joint 111 : (Welded) joint 1 : First member 1A: 1st Blank (Main Body Part) 1B: First component (main body part) 11 : Frame 12 : Protrusion 12A: Convex curve 12B: Concave curve 12C : Caulking section (taper) 12D: Parallel section 13 : Connection part 113 : (Main body part) Top plate 114 : (Main body part) Vertical wall section 115 : Flange section 2 : Second absence 2A: 2nd Blank (Reinforcement Part) 2B : Second member (reinforcement part) 21 : Hole part 22 : Frame 122 : (Reinforcement part) Top plate 123 : (Reinforcement part) Vertical wall section 124 : (Reinforcement part) Flange section 3 : Pictogram 31 : Die 32 : Pad 32A: Press-fit part 32B : (1st) Relief section 4 : Ha-hyung 41 : Punch 41A : (2nd) Relief Section

Claims

Claim 1 A joining member comprising a first member having a protrusion and a second member having a hole, joined together in the direction of plate thickness, wherein the length of the protrusion prior to joining is longer than that of the hole, and the protrusion has a width narrower than that of the hole and is formed by extending in connection with another part of the first member and bending in the direction of the second member, a convex curved portion formed by extending in connection with the convex curved portion and bending in the opposite direction of the convex curved portion and having a width narrower than that of the hole, and a concave curved portion inserted into the hole, and a tapered portion that extends in connection with the concave curved portion and widens toward the tip, and the tip has a width wider than that of the hole, and has a caulking portion that caulks to push and widen the hole. Claim 2 A joining member according to claim 1, wherein the first member has the protrusion on the flat portion and the second member has the hole on the flat portion, the first member and the second member are integrally formed by overlapping each other in the plate thickness direction, and have a U-shaped cross section or a hat-shaped cross section having at least a top plate portion and a longitudinal wall portion, and the first member and the second member are joined by press forming at a location corresponding to the flat portion. Claim 3 A joining member in which, in paragraph 2, the flat portion is at least one of the top plate portion and the longitudinal wall portion. Claim 4 A press forming die for press forming a joining member described in claim 2 or 3, wherein the first member and the second member overlap each other and integrally form a member having a U-shaped cross section or a hat-shaped cross section having at least a top plate portion and a side wall portion, and a joining portion for joining the two blanks at a location corresponding to a flat portion of the member, wherein the joining portion comprises a convex-shaped press-fit portion formed on one of a pair of opposing dies and a concave-shaped first relief portion adjacent to the press-fit portion, and a concave-shaped second relief portion formed on the other die and into which the convex-shaped press-fit portion is inserted. Claim 5 In paragraph 4, the above-mentioned pair of opposing molds is a pad and a punch, a press forming mold. Claim 6 In paragraph 4, the above-mentioned pair of opposing molds is a press forming mold, wherein the die and the punch are a die and a punch. Claim 7 A joining method comprising overlapping and joining a first member having a protrusion and a second member having a hole in the direction of plate thickness, wherein the length of the protrusion prior to joining is made longer than the hole, and a first part of the protrusion having a narrower width than the hole is bent in the direction of the second member to form a convex curve, a second part of the protrusion having a narrower width than the hole is bent in the opposite direction to the convex curve to form a concave curve, and a tapered portion having a wider width towards the tip is bent to push and widen the hole while being extended in connection with the concave curve to form a caulking portion. Claim 8 A joining method according to claim 7, wherein the first member and the second member are made of metal plates and formed by press forming, and the first member and the second member are formed by press forming, and the first member and the second member are formed by press forming, and the first member and the second member are formed by press forming, and the first member and the second member are formed by press forming, wherein the first member and the second member are formed into a target shape by press forming, and the joining method comprises: a blank processing process of processing at least the outer circumference of the metal plate to obtain a first blank and a second blank; a forming process of forming the first blank and the second blank into a target shape by press forming, respectively, to obtain the first member and the second member; and a joining process of joining the first member and the second member by the method described in claim 7. Claim 9 A joining method according to claim 8, wherein the first member and the second member are joined at least one of the top plate portion and the flange portion. Claim 10 In claim 7, the first member has the protrusion on the flat portion, and the second member has the hole portion on the flat portion; the first member and the second member are overlapped in the plate thickness direction and integrally formed to form a member having a U-shaped cross section consisting of a top plate portion and a longitudinal wall portion, or a hat-shaped cross section consisting of a top plate portion, a longitudinal wall portion, and a flange portion, and a method of joining the first member and the second member by press forming at a location corresponding to the flat portion, wherein a press forming die is provided having a joining portion having a convex-shaped press-fit portion formed on one of a pair of opposing dies, a concave-shaped first relief portion adjacent to the press-fit portion, and a concave-shaped second relief portion formed on the other die into which the convex-shaped press-fit portion is inserted, wherein the protrusion of the first member is extended to connect with another part of the first member, and the portion having a width narrower than the hole portion is inserted into the hole portion and the second relief portion by the press-fit portion. A joining method comprising a joining process in which a caulking portion having a tapered shape among the protrusions and having a wider width at its tip than the hole portion is brought into contact with the longitudinal edge of the hole portion to erect the caulking portion and position the tip of the caulking portion within the first relief portion, and caulking such that the caulking portion pushes and widens the hole portion in the width direction, and a forming process in which another portion is formed into a target shape. Claim 11 A joining method according to claim 10, wherein the flat portion is at least one of the top plate portion and the longitudinal wall portion. Claim 12 A joining method according to claim 10 or 11, wherein the pair of opposing molds are a pad and a punch, and the pad is lowered to join the overlapping members by pressing them with the punch. Claim 13 A joining method according to claim 10 or 11, wherein the pair of opposing molds are a die and a punch, and the die is lowered to join the overlapping members by pressing them together with the punch. Claim 14 A method for manufacturing a bonded member, comprising a process of overlapping and bonding the first member and the second member using a bonding method described in any one of claims 7 to 13.

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