JP7485981B2 - Manufacturing method of bonded joint structure, bonded joint structure and automobile part - Google Patents

Description

The present invention relates to a manufacturing method of a bonded joint structure, a bonded joint structure, and an automobile part.
This application claims priority based on Japanese Patent Application No. 2020-060157, filed on March 30, 2020, the contents of which are incorporated herein by reference.

The use of high-strength steel plates as structural members is being promoted in order to reduce the weight of automobiles and improve collision safety. On the other hand, spot welded joints made of high-strength steel plates have the problem that the cross tensile strength (CTS) decreases when the tensile strength of the base steel plate exceeds 780 MPa. In addition, when the tensile strength of the steel plate exceeds 1500 MPa, not only the cross tensile strength but also the tensile shear strength (TSS) tends to decrease.

If the strength of a spot welded joint decreases, there is a risk that the weld will break when the component is deformed due to a collision under very severe conditions. Therefore, even if the strength of the steel plate is improved, there is a risk that the load-bearing capacity of the component as a whole will be insufficient. Therefore, there is a demand for a joining method that improves the strength of joints made of high-strength steel plates.

Riveting is one method for improving the cross tensile strength of a joint. Riveting is a joining method in which a through hole is formed in a steel plate, a rivet (fastening member) with a head and shank is inserted into the through hole, the tip of the rivet shank is plastically deformed at room temperature, and the steel plate is crimped by the head and plastically deformed part of the rivet. For example, the following technologies are being considered for manufacturing methods of riveted joint structures, and are not limited to high-strength steel plates.

Patent document 1 discloses a method for joining two or more components together with fasteners. In this method, each component has a hole and is arranged so that the holes overlap each other to receive the fasteners within the holes, and the fasteners placed in the holes are mechanically pressurized and heated to deform the fasteners. In this way, the components are joined together.

Patent Document 2 discloses a method of riveting in which the head and tip of a rivet are sandwiched between a pair of electrodes, heated by electrical current, and pressed against each other. In this method, a spacer with a small cross-sectional area is provided between the back surface of the rivet head and the material to be riveted, and the rivet is riveted by providing a spacer with a height such that the shank of the rivet fills the rivet hole sufficiently closely, or thereafter, so that the back surface of the head comes into contact with the material to be riveted.

Patent Document 3 discloses a method of fastening a rivet in which the rivet is clamped between electrodes, heated by resistance heat through electricity, and pressure-formed, and after the electrical heating, the forming side head electrode is temporarily removed from the rivet to allow the heat to reach the tip of the rivet.

Patent Document 4 discloses a method of joining components by electric crimping of a rivet, in which a rivet hole that penetrates at least two components to be joined is formed into at least a partially tapered hole, a rivet is fitted into this rivet hole, and the rivet shaft is bulged and deformed into a shape that conforms to the tapered hole by electric crimping, and the rivet shaft and tapered hole are tightly attached to each other by thermal contraction of the rivet after electric crimping, joining them without any gaps. Here, the rivet temperature during electric crimping is said to be 700 to 900°C.

Patent Document 5 discloses a riveting method for joining multiple workpieces using a rivet, in which a rivet inserted into multiple workpieces is clamped between a pair of electrodes and pressurized while an electric current is passed through it, causing the rivet to soften due to resistance heating of the rivet itself caused by the current passing through, and the end of the rivet is crimped.

Patent Documents 1 to 5 discuss various forms of riveted joints. However, none of Patent Documents 1 to 5 discusses the cross tensile strength and tensile shear strength of the riveted joint structure, nor do they discuss configurations for improving these strengths.

The inventors have found that the cross tensile strength of a joint obtained by riveting high-strength steel plates (also called a riveted joint) is significantly higher than that of a spot-welded joint. This is believed to be because riveting, which mechanically joins steel plates, does not cause embrittlement of the joint, making it possible to maintain a high CTS for the joint made of high-strength steel plates.

However, for example, in the manufacture of automobile parts, it is not easy to use riveting instead of spot welding. In spot welding, it is necessary to heat and pressurize the steel plate. A pair of electrodes is used to heat and pressurize the steel plate. On the other hand, in riveting, it is necessary to insert a rivet into the steel plate and then heat and pressurize the rivet. Although the electrodes for spot welding can be used to heat and pressurize the rivet, in order to convert the spot welding equipment into equipment for riveting, a mechanism for supplying rivets to the steel plate must be added to the equipment. However, adding a mechanism to the joining equipment increases production costs and further reduces the versatility of the production line. In particular, adding a mechanism for a rivet supply device to the final welding line for automobile bodies in which multiple vehicle models are welded leads to a reduction in the versatility of the line.

The inventors have considered inserting rivets into through holes in steel plates beforehand and then moving the steel plates to the joining equipment. With this method, there is no need to add a rivet supply mechanism to the joining equipment. However, there have been cases where rivets have fallen off while the steel plates with rivets inserted are being moved to the joining equipment. Therefore, in order not to impair production yield, it was thought that rivets should be supplied at the joining equipment. Note that Patent Documents 1 to 5 do not consider a method for reliably and easily supplying rivets as described above.

Due to the above circumstances, there is a demand for a joining method that is highly productive without compromising the advantages of riveting.

Japanese Patent Publication No. 2006-507128 Japanese Patent Publication No. 55-27456 Japanese Patent Publication No. 53-78486 Japanese Patent Publication No. 61-165247 Japanese Patent Application Publication No. 10-205510

The present invention aims to provide a manufacturing method for a joint structure that is highly productive and capable of providing a structure with high cross tensile strength, as well as a joint structure and automotive part that are highly productive and have high cross tensile strength.

(1) A manufacturing method for a joined joint structure according to one aspect of the present invention includes passing the shank of a rivet, which has a shank and a flange provided on a first axial end of the shank, through a through hole of a first member, contacting and fixing the first member to the flange, passing the shank of the rivet through a through hole of a second member to overlap the first member and the second member, and deforming the second axial end of the shank to crimp the first member and the second member, wherein a flange protrusion is provided on a seating surface of the flange, and the flange protrusion and the first member are projection welded together to contact and fix the first member to the flange.
(2) A manufacturing method of a joined joint structure according to one aspect of the present invention includes passing the shank of a rivet, which has a shank and a flange provided on a first axial end of the shank, through a through hole of a first member, contacting and fixing the first member to the flange, passing the shank of the rivet through a through hole of a second member to overlap the first member and the second member, and deforming the second axial end of the shank to crimp the first member and the second member, wherein the rivet is provided in advance with a shank protrusion protruding radially from the shank, and the shank of the rivet may be passed through the through hole of the first member, the first member may be plastically deformed by applying pressure, and the first member may be crimped by the flange of the rivet and the shank protrusion, and the first member may be contacted and fixed to the flange.
(3) In the manufacturing method of the joint structure described in (1) or (2) above, the rivet may be clamped between a pair of electrodes in the axial direction, the rivet may be pressurized in the axial direction, and current may be passed through the pair of electrodes to deform the second end.
(4) In the manufacturing method of the joint structure described in any one of (1) to (3) above, the first member or the second member is a steel plate, and the rivet is a steel material.
(5) In the manufacturing method of the joint structure described in any one of (1) to (4) above, the first member and the second member and/or the second members may be joined together by one or more welding methods selected from the group consisting of spot welding, laser welding, and arc welding.
(6) In the manufacturing method of the joint structure described in any one of (1) to (5) above, an adhesive layer or a sealing layer may be provided around the through hole in the first member and the second member, and the adhesive layer or the sealing layer may be sandwiched between the first member and the second member.

(7) A joint structure according to another aspect of the present invention comprises a rivet, a first member, and a second member, the rivet comprising a shank and a flange provided on a first axial end of the shank, the shank passing through a through hole of the first member, the shank passing through a through hole of the second member, the first member being fixed in contact with the flange, the first member and the second member being crimped by the flange of the rivet and the second axial end of the shank, a flange protrusion being provided on a seat surface of the flange, the flange protrusion being welded to the first member, and the first member being fixed in contact with the flange.
(8) A joint structure according to another aspect of the present invention comprises a rivet, a first member, and a second member, the rivet comprising a shank and a flange provided on a first axial end of the shank, the shank passing through a through hole of the first member, the shank passing through a through hole of the second member, the first member being fixed in contact with the flange, the first member and the second member being crimped by the flange of the rivet and a second axial end of the shank, a shank protrusion provided in a radial direction of the shank, the first member being crimped by the shank protrusion, and the first member being fixed in contact with the flange, the shank protrusion being disposed outside the first member .
(9) In the joint structure described in (7) or (8) above, one or more of the first member or the second member may be a steel plate, and the rivet may be a steel material.
(10) In the joint structure described in any one of (7) to (9) above, an adhesive layer or a sealing layer may be provided around the shaft portion, and the first member and the second member may sandwich the adhesive layer or the sealing layer.
(11) In the joint structure described in any one of (7) to (10) above, the first member and the second member may be welded to each other.

(12) An automobile component according to another aspect of the present invention includes the joint structure according to any one of (7) to (11) above.
(13) The automobile part described in (12) above may be a bumper or a B-pillar.

The present invention can provide a manufacturing method for a joint structure that is highly productive and capable of providing a structure with high cross tensile strength, as well as a joint structure and automotive part that are highly productive and have high cross tensile strength.

FIG. 2 is a schematic cross-sectional view for explaining the manufacturing method of the joint structure according to the first embodiment, showing a rivet and a first member. FIG. 2 is a schematic cross-sectional view for explaining a manufacturing method of the joint structure according to the first embodiment, showing a state in which the rivet and the first member are sandwiched between the first electrode. FIG. 2 is a schematic cross-sectional view for explaining a manufacturing method of a joint structure relating to the first embodiment, showing a state in which a first member to which a flange is fixed and a second member are overlapped. FIG. 2 is a schematic cross-sectional view for explaining the manufacturing method of the joint structure according to the first embodiment, showing a state in which the rivet is sandwiched between a pair of second electrodes in the axial direction. FIG. 2 is a schematic cross-sectional view for explaining a manufacturing method of the welded joint structure according to the first embodiment, showing a state in which welding is completed. FIG. 4 is a schematic plan view for explaining the shape of a through hole in the joint structure according to the first embodiment. 10A to 10C are schematic plan views for explaining other shapes of the through hole in the joint structure according to the first embodiment. 10A to 10C are schematic plan views for explaining other shapes of the through hole in the joint structure according to the first embodiment. 10A to 10C are schematic plan views for explaining other shapes of the through hole in the joint structure according to the first embodiment. 10A to 10C are schematic plan views for explaining other shapes of the through hole in the joint structure according to the first embodiment. 10A to 10C are schematic plan views for explaining other shapes of the through hole in the joint structure according to the first embodiment. FIG. 2 is a schematic cross-sectional view for explaining a rivet provided with a flange protrusion portion. FIG. 11 is a schematic cross-sectional view for explaining a rivet provided with a recess. FIG. 2 is a schematic plan view for explaining an adhesive layer or a sealing layer provided on the member according to the first embodiment. FIG. 2 is a schematic cross-sectional view for explaining an example of a joint structure according to the first embodiment. FIG. 2 is a schematic cross-sectional view for explaining an example of a joint structure according to the first embodiment. FIG. 2 is a schematic cross-sectional view for explaining an example of a joint structure according to the first embodiment. 1 is a cross-sectional view of a B-pillar, which is an example of an automobile part according to an embodiment of the present invention. 1 is a cross-sectional view of a bumper, which is an example of an automobile part according to an embodiment of the present invention. 1 is a perspective view of a bumper, which is an example of an automobile part according to an embodiment of the present invention.

Below, the embodiments of the present invention will be described with examples, but it is self-evident that the present invention is not limited to the examples described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and materials may be applied as long as the effects of the present invention can be obtained. In addition, the components of the following embodiments can be combined with each other.

[First embodiment]
The manufacturing method of the joint structure according to the present embodiment includes passing the shank of a rivet, which includes a shank and a flange provided at a first axial end of the shank, through a through hole of a first member, contacting and fixing the first member to the flange, passing the shank of the rivet through a through hole of a second member to overlap the first member and the second member, and deforming the second axial end of the shank to crimp the first member and the second member. In other words, the manufacturing method of the joint structure according to the present embodiment is a manufacturing method of a joint structure for joining a plurality of members with a fastening member, and is characterized by including a step of preparing a first member having a through hole, one or more second members having a through hole, and a fastening member having a flange and a shank, a step of inserting the fastening member through the through hole of the first member, a step of joining the first member to the first end located at the end side where the flange of the fastening member is provided, a step of inserting the shank of the fastening member through the through hole of the second member, and a step of deforming the second end located at the other end side of the fastening member.

In the manufacturing method for the joint structure having the above configuration, before the first and second members to be joined are overlapped, a rivet is inserted into the through hole of the first member to join the first member to the rivet. This prevents the rivet from falling off when the first member is moved, and does not impair production yield. In addition, by adopting a joint structure using a rivet, the cross tensile strength can be increased.

Next, the steps for manufacturing the joint structure of this embodiment will be described.

First, a first member 100 having a through hole 101 formed therein, one or more second members 200 having a through hole 201 provided therein, and a rivet (fastening member) 300 having a shaft portion 301 are prepared. In the example of this embodiment, a case where two plate materials are joined, i.e., a case where there is one second member 200, is described as an example, but even if there are two or more second members 200, the effects unique to this invention can be obtained as long as the requirements of this invention are met. In the example of this embodiment, the rivet 300 has a shaft portion 301, a first end portion 302, a second end portion 303, and a flange 304 provided on the first end portion 302.

As a specific means for joining the first end 302 provided with the flange 304 to the first member 100, for example, as shown in Fig. 1, it is possible to provide a flange protrusion 308 on the seat surface of the flange 304 and to projection weld the flange protrusion 308 to the first member 100. Also, as another example of a specific means for contacting and fixing the first member 100 to the flange 304, it is possible to provide a recess 310 in the shaft portion 301 and crimp the first member 100, as shown in Fig. 13.
First, the former will be described. As shown in FIG. 1, the shaft portion 301 of the rivet 300 is passed through the through hole 101 of the first member 100. In this embodiment, a flange 304 is provided on the first end 302 side of the rivet 300. As shown in FIG. 1, a flange protrusion 308 is provided on the seat surface of the flange 304. The flange seat surface is the surface of the flange facing the axial direction of the rivet that faces the second end side of the rivet. In other words, the flange seat surface is the surface that contacts the first member that is the object of the flange to be fastened. The flange protrusion 308 is arranged so as to contact the surface of the first member. FIG. 1 is a cross-sectional view in a direction parallel to the plate surface of the first member 100. The first end 302 includes the flange 304.

2, a pair of electrodes (first electrodes 1010 and 1020) sandwich the flange 304 of the rivet 300 and the surface 100a of the first member 100 (100a and 100b) that is not in contact with the rivet 300. The pair of electrodes (first electrodes 1010 and 1020) then contact the flange 304 of the rivet 300 and the surface 100a of the first member 100 (100a and 100b) that is not in contact with the rivet 300, and press the flange 304 and the first member 100 in a direction parallel to the axis of the shaft 301 of the rivet 300 through these electrodes. Electricity is then passed through the pair of electrodes (first electrodes 1010 and 1020) to generate resistance heat in the flange protrusion 308 of the flange 304 of the rivet 300 and the first member 100.

This resistance heating causes the flange protrusion 308 and a portion of the first member 100 to be pressed or melted, and the pressure between the pair of electrodes (first electrodes 1010 and 1020) joins a portion of the flange 304 of the rivet 300, i.e., the flange protrusion 308 and a portion of the first member 100 in contact therewith. Once the process of contacting and fixing the first member 100 to the flange 304 is completed, the rivet will not fall off, which contributes to improved productivity.

For example, the above steps may be performed on a small parts assembly line, assembly line, or the like within an actual assembly line. Then, the step of stacking the first member 100 and the second member 200, which will be described later, may be performed on a separate assembly line.

For example, when the method of this embodiment is applied to the manufacture of car bodies, a line for assembling individual parts such as pillars may carry out the steps of preparing a first member having a through hole, one or more second members having a through hole, and a rivet having a shaft, passing the rivet shaft through the through hole of the first member, and fixing the first member in contact with a flange to supply a part to which the rivet is joined, and a car body assembly line may carry out the steps of passing the rivet shaft through the through hole of the second member to overlap the first member and the second member, and deforming the second end of the shaft to crimp the first member and the second member. This eliminates the need for rivet supply equipment such as rivets on a car body assembly line where versatility is required.

Next, as shown in FIG. 3, the shaft 301 of the rivet 300 fixed to the first member 100 via the flange is passed through the through hole 201 of the second member 200. That is, the second member 200 is superimposed on the surface 100a side of the first member 100 (100a and 100b) to which the flange 304 of the rivet 300 is not joined. When the first member 100 and the second member 200 are superimposed, the first member 100 and the second member 200 may be in contact with each other at a location other than the vicinity of the through holes 101 and 201, or these members may be separated from each other. In the examples of FIG. 3 to FIG. 5, the flange protrusion 308 is crushed and its height is slightly reduced.

Next, the second axial end 303 of the shaft 301 is deformed to crimp the first member 100 and the second member 200 together (so-called riveting). In the example shown in Figure 4, the rivet 300 is sandwiched between a pair of electrodes (second electrodes 2010 and 2020), pressure is applied to the rivet 300, and electricity is passed through the pair of electrodes (second electrodes 2010 and 2020), causing resistance heating in the rivet 300.

In this process, a pair of electrodes (second electrodes 2010 and 2020) contact the end face 302a of the first end 302 and the end face 303a of the second end 303 of the rivet 300. The pair of electrodes pressurize the rivet 300 in a direction parallel to the axis of the shaft 301.

Furthermore, in this process, electricity is passed through a pair of electrodes (second electrodes 2010 and 2020) to generate resistance heating in the rivet 300, thereby softening the rivet 300. In this state, the rivet 300 is pressurized by the pair of electrodes (second electrodes 2010 and 2020), thereby deforming the second end 303 of the rivet 300. In the example of this embodiment, as shown in FIG. 5, the second end 303 deforms to form a plastic deformation portion 306. In this deformation, the shaft portion 301 is reduced in the axial direction of the shaft portion 301, and the second end 303 is expanded radially outward of the shaft portion 301, thereby forming the plastic deformation portion 306.

Through the above steps, a joint structure 1 as shown in Fig. 5 is obtained. The joint structure 1 in Fig. 5 includes a rivet 300, a first member 100, and a second member 200. The rivet 300 includes a shaft portion 301 and a flange 304 provided at a first axial end 302 of the shaft portion 301. The shaft portion 301 passes through a through hole 101 of the first member 100, the shaft portion 301 passes through a through hole 201 of the second member 200, the first member 100 is fixed in contact with the flange 304, and the first member 100 and the second member 200 are crimped by the flange 304 of the rivet 300 and the second axial end 303 of the shaft portion 301. In other words, the joint structure 1 of Fig. 5 is a joint structure in which a plurality of overlapping members (first member 100 and second member 200) are joined using a fastening member 300, and the fastening member 300 has a shaft portion 301, a first end portion 302 provided on one end side of the shaft portion 301, a flange portion 304, a protrusion portion 308, and a second end portion 303 provided on the other end side of the shaft portion 301. In this joint structure 1, the shaft portion 301 penetrates the first member 100 and the second member 200, and the first member 100 and the second member 200 are crimped by the first end portion 302 and the second end portion 303, and the first end portion 302 is joined to the first member 100. In addition, the protrusion portion 308 and the first member 100 are joined.

The joint structure 1 having the above configuration has increased cross tensile strength as a joint structure.

There are no particular limitations on the configuration of the first member 100 or the second member 200. For example, if the first member 100 and the second member 200 are made of a plate material made of a metal material such as a steel plate, particularly a high-strength steel plate (e.g., a steel plate having a tensile strength TS of about 590 MPa or more), the strength of the rivet 300 can be improved, which is preferable.

In the manufacturing method of the joint structure according to this embodiment, it is more preferable that the tensile strength of the first member 100 or the second member 200 is 980 MPa or more. The riveting method according to this embodiment does not cause embrittlement in the high-strength steel plate, which leads to a decrease in cross tensile strength, so that when applied to joining high-strength steel plates, it is possible to provide a joint structure having high cross tensile strength.

More preferably, the first member 100 or the second member 200 is a steel plate having a tensile strength of 1180 MPa or more, and even more preferably a steel plate having a tensile strength of 1500 MPa or more. The upper limit of the tensile strength of the steel plate constituting the first member 100 or the second member 200 is not particularly limited, but may be, for example, 2700 MPa or less.

In addition, when a weld is formed in a high-strength steel plate by spot welding, the weld and its vicinity are prone to embrittlement, which can lead to a decrease in cross tensile strength. However, the joint structure according to this embodiment does not have such a cause of embrittlement, and therefore can provide a joint structure with high cross tensile strength when applied to joining high-strength steel plates.

The first member 100 and the second member 200 may be plate materials. The first member 100 may be a steel plate, an aluminum plate, a titanium plate, an alloy plate thereof, or the like. The first member 100 is preferably made of a metal material because welding or crimping is preferably used as a method of joining with the rivet 300 described above. The second member 200 may be a non-metallic material such as a steel plate, an aluminum plate, a titanium plate, an alloy plate thereof, or CFRP (Carbon Fiber Reinforced Plastics). In addition, the multiple members may each be made of different materials. For example, a combination of a steel plate and an aluminum plate, or a combination of a steel plate and a CFRP plate may be used.

In addition, various surface treatments may be performed on the first member 100 or the second member 200. For example, the first member 100 or the second member 200 may have a plating layer made of GA plating, GI plating, EG plating, Zn-Mg plating, Zn-Al plating, Zn-Al-Mg plating, Al plating, painting, and Zn-based plating (Zn-Fe, Zn-Ni-Fe) and Al-based plating (Al-Fe-Si) alloyed with the base metal by hot stamping.

There is no particular limit to the thickness of the first member 100 or the second member 200, and for example, each steel plate may have a thickness of 0.5 mm to 3.6 mm in the depth direction of the through hole 101 or 201. The thicknesses of these members may also differ from each other. The total plate thickness of the first member and the second member combined is preferably 9.0 mm or less.

The first member 100 or the second member 200 may be, for example, a two-ply plate material having a thickness of 1.6 mm and a thickness of 2.3 mm, or a three-ply plate material having a thickness of 0.75 mm, 1.8 mm, and 1.2 mm. Suitable combinations of the first member 100 or the second member 200 include, for example, a two-ply plate material having a thickness of about 0.6 mm to 2.9 mm and a two-ply plate material having a thickness of 0.6 mm to 2.9 mm, or a three-ply plate material having a thickness of 0.6 mm to 1.6 mm, a two-ply plate material having a thickness of 0.6 mm to 2.9 mm, and a three-ply plate material having a thickness of 0.6 mm to 2.9 mm.

The first member 100 or the second member 200 may be a molded product formed by cold or hot press forming, cold roll forming, or hydroforming. The members may also be formed into a pipe shape.

The configuration of the through hole 101 or 201 is not particularly limited. The shape of the through hole 101 or 201 can be, for example, a circular shape as shown in FIG. 6 when viewed in a plan view in the depth direction of the through hole 101 or 201.

The shape of the through hole, when viewed in a plan view in the depth direction of the through hole, may be an ellipse as shown in Fig. 7, a polygon as shown in Fig. 8, a sector as shown in Fig. 9, a circle with a convex part as shown in Fig. 10, or a cross as shown in Fig. 11. The shape of the rear part may also be a shape with a concave part. By making the through hole into these shapes, it is possible to prevent the components from rotating or rattling relative to each other around the rivet 300, even if the components are not firmly fixed to each other.

The shape of the through hole may be a polygon, such as a square, pentagon, hexagon, or octagon. The corners of these polygons may have curvature. Furthermore, the shape of the through hole may differ for each member.

The size of the through hole 101 or 201 must be larger than the diameter of the shaft portion 301 of the rivet 300.

The size of the through hole 101 or 201 may be constant in the depth direction. On the other hand, the size of the through hole 101 or 201 may be stepped or tapered in the depth direction.

The through holes 101 or 201 can be formed by any means, such as laser cutting, punching with a die, or perforation with a drill. For example, when the first member 100 or the second member 200 is a hot-stamped steel plate, the means for forming the through holes is preferably hot die punching or laser cutting.

The diameter of the through hole 101 or 201 (converted to a circle-equivalent diameter if the through hole is not circular) may be the same for all members, or may be different for each member. In normal riveting, it is considered preferable to make the diameter of the through hole 101 or 201 constant from the viewpoint of reducing the gap at the joint. The degree of difference in the diameter of the through hole 101 or 201 is not particularly limited, but it is preferable that, for example, the difference in the diameter of the through hole in adjacent members is within the range of 0.3 mm to 3.0 mm.

It is desirable that the minimum diameter of the through hole 101 or 201 is 0.1 mm to 5.0 mm larger than the maximum diameter of the shaft 301 of the rivet 300 to be inserted. If this difference is smaller than 0.1 mm, the insertion performance deteriorates, and if it is larger than 5.0 mm, it becomes difficult to sufficiently fill the gap of the through hole 101 or 201 with the deformed rivet 300. More desirably, it is in the range of 0.3 mm to 3.0 mm, and optimally, it is in the range of 0.3 mm to 1.5 mm. In addition, the deviation of the central axes of the through holes 101 and 201 between multiple joined materials is desirably within 1.50 mm, and even more desirably 0.75 mm or less.

The size of the through hole 101 or 201 may be constant in the depth direction of the first member 100 or the second member 200. On the other hand, a stepped or tapered shape in which the size of the through hole 101 or 201 varies in the depth direction may be applied to the through hole 101 or 201. In addition, the central axes of the through holes between multiple joined materials do not have to coincide.

In addition, the depth direction of the through hole 101 or 201 may coincide with the axial direction of the shank 301 of the rivet 300.

The configuration of the rivet 300 is not particularly limited, and can be appropriately selected according to the thickness and mechanical properties of the first member 100 and the second member 200, which are the materials to be joined, and the size of the through holes 101 and 201. For example, the diameter of the shaft portion 301 of the rivet 300 (if the cross section of the shaft portion 301 is not circular, it is converted to the circle-equivalent diameter of the shaft portion 301) may be 3.0 mm or more from the viewpoint of ensuring joint strength. In addition, if the shaft diameter of the rivet 300 is too large, there is a risk that the current density will decrease and the rivet will not easily soften, so the upper limit of the shaft diameter may be 12.0 mm or less.

The length of the shank 301 (the length of the rivet 300 minus the thickness of the flange 304 at the first end 302) must be greater than the combined thickness of the first member 100 and the second member 200, and in the case of a rivet having a flange, more preferably falls within the following range:
(Total thickness of the members + diameter of the shaft portion x 0.3) ≦ Length of the shaft portion ≦ (Total thickness of the members + diameter of the shaft portion x 2.0)

By making the length of the shaft portion 301 of the rivet 300 equal to or greater than the total thickness of the first member 100 and the second member 200 plus the diameter of the shaft portion 301 x 0.3, the size of the plastically deformed portion 306 after the second end portion 303 of the shaft portion 301 is deformed can be ensured, and the joint strength can be further increased. By making the length of the shaft portion 301 equal to or less than the total thickness of the first member 100 and the second member 200 plus the diameter of the shaft portion 301 x 2.0, manufacturing efficiency can be improved. The total thickness of the members is the sum of the thicknesses of the first member 100 and the second member 200 that are overlapped in the depth direction of the through hole.

The diameter of the shank 301 may be constant. Alternatively, the shape of the shank 301 may be such that the diameter of the shank 301 decreases toward one end of the rivet 300 (so-called tapered shape). A tapered portion may be formed over the entire shank 301, or a tapered portion or a hemispherical portion may be formed only on a part of the shank 301. A rivet 300 having a tapered or hemispherical shape is more preferable because it is easier to insert into the through hole 101 or 201.

As shown in FIG. 1, the first end 302 of the rivet 300 may have a general flange shape. For example, the first end 302 may be hemispherical (round head), discoid (flat head), or conical (dish head) with a flat surface. The first end 302 including the flange 304 may have a polygonal shape such as a circle, a square, or a hexagon in plan view in the axial direction of the shaft 301 of the rivet 300. A recess for positioning the electrode may be provided in the center of the electrode side of the first end 302.

The rivet 300 must be made of a metal such as steel, stainless steel, titanium, or aluminum. For example, when the member is a steel plate, the rivet 300 is preferably made of a steel material such as carbon steel. The rivet 300 may not be surface-treated, but may be surface-treated if corrosion resistance is required. For example, the surface of the rivet 300 may be zinc-based, aluminum-based, chromium-based, nickel-based, or chromate-treated. In particular, when corrosion resistance is required or when the rivet is to be used without post-painting, a stainless steel rivet is preferable. The rivet is manufactured, for example, by cutting a coil wire and performing cutting processing or cold forging processing. From the viewpoint of productivity, cold forging processing is preferable. The rivet may be as processed, but when the rivet is made of steel, it may be manufactured by cold forging and then heat-treated by quenching and tempering. By heat treatment, the hardness of the entire rivet, including the flange 304, is increased, thereby further improving the joint strength.

In the manufacturing method of the joint structure according to this embodiment, it is more preferable that one or more of the first member 100 and the second member 200 are steel plates and the rivet 300 is a steel material. This has the effect of suppressing corrosion due to contact between dissimilar metals. In particular, when the first member 100 and the second member 200 are high-strength steel materials, it is more preferable that the rivet 300 is also a high-strength steel material having an appropriate strength.

The application of pressure and current by the electrodes (first electrodes 1010 and 1020, second electrodes 2010 and 2020) is not particularly limited as long as the conditions are met for deforming the rivet 300 into the desired shape.

(First electrode)
2, the structure of the first electrodes 1010 and 1020 requires that one of the pair of electrodes (first electrode 1020) is capable of supporting the first end 302 of the rivet 300, and the other (first electrode 1010) is in contact with the surface 100a of the first member 100 without contacting the shank 301 of the rivet 300. This is because it is necessary to prevent variation in the joining state between the first member 100 and the flange 304 due to current shunting to the shank 301. For this reason, it is desirable to isolate the shank 301 and the first electrode 1010 with an insulator such as bakelite.

The structure of the first electrode is not particularly limited. For example, an electrode for welding a weld bolt can apply pressure and electricity. Therefore, this may be used to perform the joining according to this embodiment. The shape of the electrode can be appropriately selected according to the shape of the rivet. Examples of materials for the electrode include chromium copper, alumina-dispersed copper, and chromium zirconium copper, which have excellent electrical conductivity. The shapes of the pair of electrodes arranged above and below may be different.

As shown in Figure 12, a flange protrusion 308 is provided on the seat surface of the flange 304. Then, in the process of joining the first end portion 302 and the first member 100, the flange 304 and the first member 100 are joined via the flange protrusion 308 by projection welding.

The shape of the flange protrusion 308 may be a circle, a polygon, a crescent, or a ring surrounding the shaft. Since the rivet 300 is joined to the first member 100 by its flange 304, it is preferable that the diameter of the first end 302 including the flange 304 is 3.0 mm or more larger than the diameter of the through hole 101 of the first member 100.

Flange protrusions 308 preferably have a height of 0.5 mm to 3.0 mm and a width of 1.0 mm or more. Optimally, flange protrusions 308 have a height of 0.7 mm to 1.6 mm. Optimally, flange protrusions 308 have a width of 1.4 mm to 3.6 mm. More preferably, the number of flange protrusions 308 is three or four.

Moreover, it is more preferable that the thickness of the flange 304 is 0.8 mm to 5.0 mm. If the thickness of the flange 304 is less than 0.8 mm, sufficient joint strength cannot be obtained. On the other hand, if the thickness of the flange 304 is more than 5.0 mm, the flange (head) is too large and is likely to interfere with other parts.

Pressurization is started before the current is passed. For example, the rivet 300 and the first member 100 may be sandwiched between a pair of electrodes (first electrodes 1010 and 1020) and a current may be passed through them while they are under pressure, concentrating the current at the flange protrusion 308 of the rivet 300 to form a joint between the first member 100. By starting the pressure before the current is passed, the current can be stabilized.

The pressure application conditions and current application conditions (current value, voltage value, current application time, etc.) for the rivet 300 are not particularly limited and can be selected appropriately depending on the shape and material of the rivet 300.

As more preferable pressure and current application conditions for the rivet 300, for example, the following can be adopted. Voltage values are omitted, but the voltage values are determined according to the rivet 300 and the current value.

The pressure applied by the first electrodes 1010 and 1020 is preferably 150 kgf to 1000 kgf because this ensures a stable current flow area. More preferably, the pressure is 250 kgf to 600 kgf. The pressure can be set to a constant value, but the pressure can be changed during current flow as necessary.

A current flow time of 0.05 to 1.00 seconds is preferred because it allows a joint to be obtained without overheating the components. More preferably, the current flow time is 0.07 to 0.30 seconds.

A current value of 6 kA to 18 kA is preferred because it forms a good joint. Current may be passed once or twice or more. If hardening of the joint is a problem, the joint may be tempered. For example, after the first current is passed, pressure is continued without current to temporarily cool the joint, and then a second current is passed at a current value lower than the first, thereby tempering the joint. Pulse current, or current with an upslope that gradually increases the current, or a downslope that gradually decreases the current, may also be used. A holding time of 0.01 to 1.00 seconds from the end of current to the end of pressure is preferred because this stabilizes the joint strength.

The rivet 300 is inserted into the through hole 101 of the first member 100, for example, by a rivet supply device.

(Second electrode)
The structure of the second electrode is not particularly limited. For example, since the electrode for spot welding can perform pressure and current flow, it may be used to perform the joining according to this embodiment. The shape of the electrode can be appropriately selected according to the shape of the rivet. For example, the second electrode may be a flat type electrode, a single R type, a CF type, or a DR type. Examples of the material of the electrode include chromium copper, alumina-dispersed copper, and chromium zirconium copper, which have excellent electrical conductivity. The shapes of the upper and lower electrodes may be different.

The power source for the welding machine can be single-phase AC, DC inverter, or AC inverter. The gun type can be fixed, C type, or X type.

In order to obtain a good joint, it is desirable for the direction of pressure applied to the rivet by the electrode to be at an angle of 10° or less to the direction in which the rivet axis extends. More desirably, it is 4° or less.

The current may be passed once (so-called single current), but if necessary, two-stage current, three or more-stage current, or current may be adjusted to perform tempering current. Pulse current, or current with an upslope in which the current is gradually increased or a downslope in which the current is gradually decreased may also be used. A high current may also be passed in the first half of the current to form a softened portion, and the current may be decreased in the second half.

The current may be passed only once, or may be passed in two or three stages as required, or may be pulsed, or may be passed with an upslope current gradually increasing or a downslope current gradually decreasing. It is also possible to pass a high current in the first half of the current to soften the rivet, and then to decrease the current in the second half.

In the process of deforming the second end 303 of the rivet 300 after the process of inserting the shaft 301 of the rivet 300 through the through hole 201 of the second member 200, pressure is started before current is passed through. For example, the rivet 300 may be sandwiched between a pair of electrodes (second electrodes 2010 and 2020) and current is passed through the rivet 300 in a pressurized state, and the rivet 300 may be softened and crimped by the resistance heating of the rivet 300 itself due to the current passing through. By starting pressure before current is passed through, the current can be stabilized.

The pressure application conditions and current application conditions (current value, voltage value, current application time, etc.) for the rivet 300 are not particularly limited and can be selected appropriately depending on the shape and material of the rivet 300.

For example, the following can be adopted as more preferable conditions for the rivet 300. Although the voltage value is not stated, the voltage value is determined according to the rivet 300 and the current value. If the diameter of the shaft portion 301 of the rivet 300 is increased, the heat input can be increased by increasing either or both of the current value and the current flow time.

A pressure of 150 kgf to 1000 kgf applied by the electrodes is preferred because this can be performed with a typical spot welding machine. More preferably, the pressure is 250 kgf to 600 kgf. The pressure may be set to a constant value, but the pressure may be changed during current application as necessary. If blowholes occur in the softened rivet, a downslope may be used for current application, or the pressure may be increased in the latter half of current application or after current application has ended in order to eliminate the blowholes. The pressure may also be changed during the holding time after current application has ended.

The current flow time is preferably 0.15 to 2.00 seconds, because this is the time required for sufficient softening and is also highly productive in a short period of time. More preferably, the current flow time is 0.20 to 1.00 seconds.

The current value is preferably 4 kA to 13 kA because stable softening can be achieved within the above current application time.
The retention time from the end of energization to the end of pressurization is preferably 0.01 to 1.00 seconds, because this is a short time and provides high productivity.

The rivet may be cooled after the pressurization and current application. The cooling conditions of the rivet are not particularly limited. After the current application is completed, the rivet may be left in the air to cool naturally. The rivet may be accelerated by contacting the rivet with an electrode through which a refrigerant flows. By accelerating the cooling of the rivet, the rivet can be quenched and the joint strength of the joint can be further increased. Accelerated cooling may be performed using a holding time, which is the time from the end of current application to the release of the electrode, and from the viewpoint of improving productivity, the accelerated cooling (holding) time is preferably 3 seconds or less. From the viewpoint of improving productivity and ensuring joint quality, the holding time is more preferably 0.01 seconds or more and 1.00 seconds or less. The holding time is optimally 0.10 seconds or more and 0.80 seconds or less.

The tip of the shaft portion 301 of the rivet 300 is plastically deformed by pressure and current flow to form a plastically deformed portion 306. The flange 304, together with the plastically deformed portion 306, serves to clamp (crimp) the first member 100 and the second member 200 together.
The thickness of the plastically deformed portion 306 is preferably set to 0.8 mm to 5.0 mm in order to ensure the joining strength and prevent interference with other components.

In one embodiment of the present invention, in the process of joining the first end 302 of the rivet 300 to the first member 100 (the process of contacting and fixing the first member 100 to the flange 304), the first end 302 and the first member 100 may be joined by crimping.

Next, a method of crimping to join the first end provided with the flange and the first member will be described. In this method, as shown in FIG. 13, the shaft portion 301 of the rivet 300 has a shaft protrusion 309 that protrudes in the radial direction of the shaft portion 301. The radial direction of the shaft portion 301 is the direction from the axis of the shaft portion 301 toward the outer periphery. By crimping the first member 100 with the shaft protrusion 309, the first member 100 can be fixed in contact with the flange 304. Specifically, the first member 100 is fitted between the shaft protrusion 309 and the flange 304, and then the shaft protrusion 309 is plastically deformed toward the flange 304 as desired, thereby crimping the first member 100 with the shaft protrusion 309.
As shown in FIG. 13 , a recess 310 that surrounds the shaft 301 may be provided near the seat (the surface that contacts the first member 100) of the first end 302, and the edge of the through hole 101 of the first member 100 may be crimped by this recess 310. The recess 310 is, for example, a space between the shaft protrusion 309 and the flange 304. Specifically, first, the shaft 301 of the rivet 300 is inserted into the through hole 101 of the first member 100 to which the rivet 300 is to be attached, and the first end 302 is pushed into the member side by a punch. This causes the periphery of the through hole 101 of the first member 100 to fit into the recess 310. In this way, the rivet 300 can be joined to the first member 100 by the flange 304 and the recess 310 of the rivet 300. Furthermore, after this step, the back surface of the first member 100 (the surface opposite to the flange 304) may be deformed toward the flange 304 side with a punch having a protrusion, and a part of the first member 100 may be further pressed into the recess 310, thereby achieving a stronger bond. A protrusion may be provided on the first member 100 side of the flange 304, but it is preferable not to provide one.

In the manufacturing method of the joint structure according to this embodiment, it is not prohibited to use other joining means in combination. By combining two or more different joining means, the joining strength of the joint structure can be further increased.

For example, the manufacturing method of the joint structure according to the present embodiment may further include a step of joining the first member 100 and the second member 200, the second members 200 together (when there are a plurality of second members 200), or all members together by one or more welding methods selected from the group consisting of _spot welding, laser welding, and arc welding (MAG welding, MIG welding, CO 2 welding, plasma welding). Welding may be performed before or after riveting. Also, a welding step may be included during the riveting step. For example, the manufacturing method of the joint structure according to the present embodiment may include a step of fixing a rivet to the first member, overlapping the first member and the second member, performing spot welding at a position different from the riveting, and then crimping the rivet to join. At this time, the rivet before crimping serves as a positioning pin and is desirable because it contributes to improving the assembly accuracy of the parts to be joined.

In addition, in the manufacturing method of the joint structure according to this embodiment, an adhesive layer or a seal layer may be provided around the through holes 101, 201 of the first member 100 and the second member 200, and the adhesive layer or the seal layer may be sandwiched between the first member 100 and the second member 200. In other words, before the step of inserting the shaft portion 301 of the rivet 300 into the through hole 201 of the second member 200 and overlapping the first member 100 and the second member 200, a step of providing an adhesive layer or a seal layer at least around the through hole 101 or 201 of the first member 100 or the second member 200 may be further included. The joint structure obtained in this way has an adhesive layer or a seal layer around the shaft portion 301, and the adhesive layer or the seal layer is sandwiched between the first member 100 and the second member 200.

The adhesive layer improves the rigidity and vibration resistance and also improves the joint strength. The seal layer improves water resistance and corrosion resistance. In spot welding of components, it may be necessary to separate the adhesive application area from the spot welding area to prevent explosion. However, in the manufacturing method of the joint joint structure according to this embodiment, since explosion does not occur, there is an advantage that the location where the adhesive layer or seal layer is provided is not limited. In addition, in the joining of dissimilar metals or metal and CFRP, contact corrosion of the overlapping surface can be prevented. In addition, a sealer may be applied to cover at least one of the flange 304 and the plastic deformation part 306. This can prevent water from entering through the gap between the flange 304 or the plastic deformation part 306 and the steel plate. Furthermore, in the case of joining dissimilar metals or joining metal and CFRP, at least one metal plate may be subjected to chemical conversion treatment and painting before riveting. This can further suppress contact corrosion between dissimilar materials and increase corrosion resistance.

Epoxy or rubber-based adhesives are preferably used. In the case of a thermosetting adhesive, the adhesive may be cured by heating in a baking process on an electrocoating line after riveting. In the case of a reactive curing adhesive, the adhesive is cured by allowing time to pass after riveting. A spot sealer is preferably used as the sealer. The periphery of the through hole is defined as the overlapping surface of the components around the through hole. A resin adhesive tape such as an ionomer may also be used as the adhesive layer.

Figure 14 illustrates an example of a location 150 where an adhesive layer or sealing layer is provided around the through hole 101 of the first member 100.

In the joint structure according to this embodiment, in a cross-sectional view parallel to the axis of the rivet shank, the top surface of the first end and/or the second end may be located closer to the shank than a position 0.6 mm away from the surface of the first member and/or the second member near the rivet in the direction along the axis of the shank. Preferably, the top surface of the first end and/or the second end is closer to the shank than the surface (outer surface) of the plate material near the rivet. This makes it possible to suppress interference with other parts. In the example of FIG. 15 and FIG. 17, the top surface 316 of the plastically deformed portion 306 of the rivet 300 is closer to the shank 301 than the surface of the second member 200 near the rivet 300 (closer to the shank 301 than the dotted line H). In the example of Fig. 16, the top surface 312 and the top surface 316 of both the first end 302 and the plastically deformed portion 306 of the rivet 300 are located closer to the shank 301 than the surfaces of the first member 100 and the second member 200 near the rivet 300 (closer to the shank 301 than the dotted line H). Here, the surface (outer surface) of the first member 100 or the second member 200 means the surface of each member that is not in contact with the other member (surface 100b of the first member 100, surface 200b of the second member 200). The dotted line H in Figs. 15 to 17 is an extension of the surface of the first member 100 or the second member 200. 15 to 17, top surface 312 of first end 302 and/or top surface 316 of plastically deformed portion 306 are closer to shaft portion 301 than the surface (outer surface) of the plate material in the vicinity of rivet 300, but top surface 312 of first end 302 and/or top surface 316 of plastically deformed portion 306 may protrude from the outer surface by a maximum of 0.6 mm. That is, even if top surface 312 of first end 302 and/or top surface 316 of plastically deformed portion 306 protrudes from dotted line H by 0.6 mm in the examples of Figures 15 to 17, the effect of suppressing interference with other components can be obtained.

Before or after riveting using the above-mentioned method, the first member 100 and/or the second member 200 may be press-formed to deform the first member 100 and/or the second member 200 near the rivet 300, so that the top surface 312 of the first end 302 and/or the top surface 316 of the plastically deformed portion 306 are closer to the shaft portion 301 than a position 0.6 mm away from the surface of the first member 100 and/or the second member 200 toward the side away from the shaft portion 301. In the example of FIG. 15, the portion of the second member 200 near the rivet 300 is deformed toward the first member 100. In the example of FIG. 16, the portion of the first member 100 near the rivet 300 is deformed toward the second member 200, and the portion of the second member 200 near the rivet 300 is deformed toward the first member 100. In the example of Fig. 17, a portion of the second member 200 near the rivet 300 is deformed towards the first member 100, and a portion of the first member 100 near the rivet 300 is deformed to correspond to the second member 200. Note that in Figs. 15 to 17, the above-mentioned flange protrusion 308 or shaft protrusion 309 is omitted.

The automobile part according to the present invention is provided with the joint structure according to the above-mentioned embodiment. This provides high joint strength. The automobile part is, for example, a bumper or B-pillar, which is an important component for ensuring collision safety.

Figure 18 shows a cross-sectional view of a B-pillar, which is an example of an automobile part according to one embodiment of the present invention, in which members 11 are joined by rivets 410 and 420. Figure 19 shows a cross-sectional view of a bumper, which is an example of an automobile part according to one embodiment of the present invention, in which members 11 are joined by rivet 510. These automobile parts are joined by the joint structure according to the present invention.

Figure 20 shows an example of combining the joint structure according to the above-mentioned embodiment with a welded portion (a welded portion formed by one or more welding methods selected from the group consisting of spot welding, laser welding, and arc welding). Figure 20 shows a bumper structure including a structure in which members 11 are joined. As shown in Figure 20, for example, the joint structure of the present invention (rivet 610 shown by the black circle in Figure 20) may be used in an area where high stress is expected to be applied during a collision, and inexpensive spot welding (spot welded portion 800 shown by the white circle in Figure 20) may be used in other joint locations.

In addition, A-pillars, side sills, roof rails, floor members, front side members, rear side members, floor pans, front suspension towers, tunnel reinforcements, dash panels, torque boxes, seat frameworks, seat rails, battery case frames, and the joints between these pillars (the joints between the B-pillars and side sills, the joints between the B-pillars and roof rails, and the joints between the roof cross member and roof rails) may also be automotive parts according to one embodiment of the present invention.

The following describes an embodiment of the present invention.

Examples 1, 2, 3, and 7 shown in Table 1 are examples of the present invention in which two members are riveted together using the method described in the above embodiment to produce a joint structure. Examples 4, 5, and 6 are comparative examples in which two members are spot welded together to produce a joint structure.

The test materials used were a 1.6 mm thick steel plate with a tensile strength of 1.80 GPa, a 1.6 mm thick steel plate with a tensile strength of 1.50 GPa, and a 2.0 mm thick steel plate with a tensile strength of 0.78 GPa.

(Examples 1 to 3)
As the first step, the projection welding method described in the above embodiment was carried out. Specifically, a through hole with a diameter of 7 mm was previously drilled in the first member by a laser pierce. As a rivet, a rivet made of low carbon steel, with a flange diameter of 15 mm, a shaft diameter of 6 mm and a length of 10 mm, and having three hemispherical protrusions with a diameter of 2.5 mm on the flange was used for projection welding with the first member. The welding conditions were a pressure of 400 kgf, a current time of 0.15 seconds, a current value of 10 kA, and a holding time of 0.1 seconds. The material was a Cu-Cr alloy. The first electrode was cylindrical as shown in FIG. 2. The inner diameter of the cylinder was 8 mm. The second electrode was a flat electrode, and the material was a Cu-Cr alloy.

In the second process, the rivet joined to the first member was inserted into a 7 mm diameter through hole in the second member that had been previously drilled with a laser pierce, and the stud was clamped between the electrodes of a spot welding machine while applying pressure and current to deform and crimp the stud. A flat electrode made of a Cu-Cr alloy was used, with a pressure of 400 kgf, current time of 333 msec, current value adjusted to 6 kA to 8 kA, and hold time of 300 msec.

(Example 7)
In Example 7, a carbon steel rivet was used having a flange diameter of 12 mm, a shaft length of 10 mm, a shaft diameter of 6 mm, and a length of 1.6 mm, as shown in Fig. 13. This rivet was provided with a shaft protrusion having a height of 0.6 mm.

The first step was carried out by cold crimping. A through hole with a diameter of 7 mm was previously drilled in the first member using a laser pierce. A rivet was inserted into the through hole in the first member and pressure was applied by clamping it between a punch and a die. The first member was plastically deformed by the pressure, and was crimped by being pressed into the space between the rivet shank protrusion 309 and the seat surface of the flange 304 (i.e., the recess 310) as shown in Figure 13.

In the second process, the rivet joined to the first member was inserted into a 7 mm diameter through hole in the second member that had been previously drilled with a laser pierce, and the stud was clamped between the electrodes of a spot welding machine while applying pressure and current to deform and crimp the stud. A flat electrode made of a Cu-Cr alloy was used, with a pressure of 400 kgf, current time of 333 msec, current value adjusted to 6 kA to 8 kA, and hold time of 300 msec.

(Examples 4 to 6)
In Examples 4 to 6, joining was performed by spot welding as a comparative example. The spot welding conditions were as follows: a DR-type electrode with a tip of 6 mm was used, and current was applied at a pressure of 400 kgf, a current application time of 333 msec, a current of 7 kA, and a holding time of 300 msec.

The CTS of these test pieces was evaluated in accordance with JIS Z3137. The results are shown below.

As shown in Table 1, using the method of the present invention, the CTS of a riveted joint was dramatically improved compared to the CTS of a spot welded joint.

In addition, in the example of the invention, the rivets did not fall off when handling the steel plates joined with the rivets, and the steel plates could be easily joined together. From this, it can be understood that the manufacturing method of the joint structure of the present invention has excellent productivity even in an actual production line.

The present invention provides a method for manufacturing a joint structure that is highly productive and capable of providing a structure with high cross tensile strength, as well as a joint structure and automotive part that are highly productive and have high cross tensile strength, and thus has high industrial applicability.

REFERENCE SIGNS LIST 1 Joint structure 11 Member 100 First member 100a, 100b Surface of first member 101, 201 Through hole 150 Location where adhesive layer or seal layer is provided 200 Second member 200b Surface of second member 300, 410, 420, 510, 610 Rivet 301 Shaft portion 302 First end portion 303 Second end portion 304 Flange 306 Plastically deformed portion 308 Flange protrusion portion 309 Shaft protrusion portion 310 Recessed portion 312, 316 Top surface 800 Spot welded portion 1010, 1020 First electrode 2010, 2020 Second electrode

Claims (13)

Passing a shank of a rivet having a shank and a flange provided at a first end in an axial direction of the shank through a through hole of a first member;
fixing the first member in contact with the flange;
Passing the shaft portion of the rivet through a through hole of a second member, stacking the first member and the second member, and deforming a second end portion of the shaft portion in the axial direction to crimp the first member and the second member.
Including,
A flange protrusion is provided on the seat surface of the flange,
A manufacturing method for a joint structure, comprising projection welding the flange protrusion and the first member to bring the first member into contact with the flange and fix it thereto. Passing a shank of a rivet having a shank and a flange provided at a first end in an axial direction of the shank through a through hole of a first member;
fixing the first member in contact with the flange;
Passing the shaft portion of the rivet through a through hole of a second member, stacking the first member and the second member, and deforming a second end portion of the shaft portion in the axial direction to crimp the first member and the second member.
Including,
The rivet is provided in advance with a shaft protrusion protruding in a radial direction of the shaft portion,
A manufacturing method for a joined joint structure, comprising: passing the shank of the rivet through a through hole of the first member; plastically deforming the first member by applying pressure; crimping the first member with a flange and the shank protrusion of the rivet; and fixing the first member in contact with the flange. 3. The method for manufacturing a joint structure according to claim 1, further comprising the steps of: clamping the rivet between a pair of electrodes in the axial direction; pressurizing the rivet in the axial direction; and passing current through the pair of electrodes to deform the second end. The method for manufacturing a joint structure according to any one of claims 1 to 3, wherein the first member or the second member is a steel plate, and the rivet is a steel material. The manufacturing method of any one of claims 1 to 4, wherein the first member and the second member and/or the second members are joined to each other by one or more welding methods selected from the group consisting of spot welding, laser welding, and arc welding. An adhesive layer or a seal layer is provided around the through hole in the first member and the second member,
The method for manufacturing a joint structure according to any one of claims 1 to 5, wherein the adhesive layer or the sealing layer is sandwiched between the first member and the second member. A rivet, a first member, and a second member,
The rivet includes a shank and a flange provided at a first axial end of the shank,
The shaft portion passes through a through hole of the first member,
The shaft portion passes through a through hole of the second member,
the first member is fixed in contact with the flange;
Furthermore, the first member and the second member are crimped by a flange of the rivet and a second axial end of the shaft portion,
A flange protrusion is provided on the seat surface of the flange,
the flange protrusion and the first member are welded together,
The first member is fixed in contact with the flange to form a joint structure. A rivet, a first member, and a second member,
The rivet includes a shank and a flange provided at a first axial end of the shank,
The shaft portion passes through a through hole of the first member,
The shaft portion passes through a through hole of the second member,
the first member is fixed in contact with the flange;
Furthermore, the first member and the second member are crimped by a flange of the rivet and a second axial end of the shaft portion,
A shaft protrusion is provided in a radial direction of the shaft portion,
The first member is fixed to the flange by crimping the shaft protrusion,
The shaft protrusion is disposed outside the first member.
Bonded joint structure. 9. The joint structure according to claim 7 or 8, wherein at least one of the first member or the second member is a steel plate, and the rivet is a steel material. An adhesive layer or a seal layer is provided around the periphery of the shaft portion,
The joint structure according to any one of claims 7 to 9, wherein the first member and the second member sandwich the adhesive layer or the sealing layer. The joint structure according to any one of claims 7 to 10, wherein the first member and the second member are welded. An automobile part having a joint structure according to any one of claims 7 to 11. The automotive part according to claim 12, which is a bumper or a B-pillar.

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