JP7027591B1 - Rivet and dissimilar material joining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the joining strength and the appearance quality after joining in a rivet which penetrates a second member overlapped with a first member and is welded to the first member by resistance welding. SOLUTION: The rivet 1 is provided with a head portion 11 and a shaft portion 12 which penetrates a second member 3 stacked on the first member 2 and is welded to the first member 2 by resistance welding. The outer diameter of the shaft portion 12 protruding from the head 11 and penetrating the second member 3 is smaller than the outer diameter of the head 11. The shaft portion 12 has a hole 14 extending from the tip end toward the head portion 11. [Selection diagram] Fig. 1

Description

The present invention relates to a rivet that joins a plurality of workpieces by fastening by caulking and welding by resistance welding, and a method for joining dissimilar materials using the rivet.

High strength is required for vehicle body parts. In addition to this, in recent years, this type of vehicle body parts has been required to be lightweight. For this reason, for example, high-strength steel and aluminum materials have been used as the materials constituting the vehicle body parts. Further, a composite material in which a high-strength steel and an aluminum material are integrated has come to be used.

In integrating the high-strength steel and the aluminum material, for example, a rivet as described in Patent Document 1 is used. The rivet has a disc-shaped head and a columnar shaft portion projecting from the axial center portion of the head. An annular groove is formed on the head so as to surround the shaft portion.
Patent Document 1 describes a dissimilar material joining method in which a first member made of an iron plate and a second member made of an aluminum plate are overlapped and joined by rivets. According to this dissimilar material joining method, the rivet is pushed into the second member so that the tip of the shaft portion comes into contact with the first member, and a welding current is passed in a state where a part of the second member is replaced with the shaft portion. Is welded to the first member by resistance welding.

Japanese Unexamined Patent Publication No. 2020-6499

In the rivet shown in Patent Document 1, there is a limit in increasing the joining strength, and there is a possibility that the appearance quality after joining may be impaired.
There are two possible reasons why the joint strength cannot be increased.
The first reason is that when the rivet penetrates the second member, a part of the second member may not be sufficiently replaced with the shaft portion of the rivet. For this reason, the rivet cannot sufficiently contact the first member, and the nugget generated during resistance welding becomes small, so that the joint strength cannot be increased.

The second reason is that the metal material (aluminum material) extruded by the shaft portion being pushed into the second member may be unevenly accommodated in the annular groove of the rivet. Since the metal material accommodated in the annular groove has a function of connecting the head of the rivet and the second member, it is desirable that the metal material is evenly accommodated in the entire area of the annular groove. However, if this metal material is unevenly accommodated in the annular groove, a portion where the bond between the head and the second member is weak is generated, so that the joint strength is lowered.

The reason why the appearance quality after joining is impaired is that not all of the metal material extruded at the time of joining is accommodated in the annular groove of the head. The extruded metal material may jump out of the head without entering the annular groove, or may scatter outward without being able to fit in the annular groove. The metal material scattered on the surface side (outside of the rivet) of the second member adheres to the surface of the second member, and the appearance quality of the product is impaired. Further, the molten metal material may come out on the surface side of the second member at the time of joining, and in such a case, the molten metal material adheres to the surface of the second member and solidifies to form an aluminum ingot. If the aluminum ingot adheres to the surface of the second member, it may adversely affect the paintability of the electrodeposition coating.
If the metal material extruded at the time of joining is blown into the atmosphere, the factory environment will be polluted.

An object of the present invention is to improve the joint strength and the appearance quality after joining in a rivet that penetrates a second member stacked on the first member and is welded to the first member by resistance welding. Is.

In order to achieve this object, the rivet according to the present invention is a rivet having a head portion and a shaft portion which penetrate a second member overlapped with the first member and are welded to the first member by resistance welding. The outer diameter of the shaft portion protruding from the head portion and penetrating the second member is smaller than the outer diameter of the head portion, and the shaft portion has a hole extending from the tip toward the head portion. be.

INDUSTRIAL APPLICABILITY The present invention may have a plate-shaped head having a flat facing surface facing the surface of the second member opposite to the first member in the rivet.

In the present invention, in the rivet, the depth of the hole extending from the tip of the shaft portion toward the head is the depth at which a vacant room having a predetermined volume is formed inside the head portion, and the vacant room is formed. The volume of the shaft portion may be a volume corresponding to the volume of the shaft portion that has entered the second member with the shaft portion penetrating the second member.

In the present invention, in the rivet, the opening side end portion of the hole may be formed in a tapered shape in which the opening width gradually decreases from the tip of the shaft portion toward the head portion.

In the present invention, in the rivet, the tip portion of the shaft portion may be formed in a tapered shape in which the formation width gradually decreases toward the tip, and the hole may be opened at the center of the taper.

In the present invention, in the rivet, the head is formed in a disk shape, and the portion of the head protruding outward in the radial direction from the shaft portion has a constant thickness over the entire radial direction. It may be formed as follows.

In the present invention, in the rivet, the head portion has a disk portion protruding radially outward from the shaft portion and a cylinder projecting from the outer peripheral portion of the disk portion in the projecting direction of the shaft portion. It may be formed by a tubular wall portion made of.

In the present invention, in the rivet, the shaft portion is formed in a cylindrical shape in which the hole is formed in the shaft center portion, and at least one of the outer peripheral portion and the inner peripheral portion of the shaft portion has a cross-sectional wave shape. It may be formed.

The dissimilar material joining method according to the present invention is a dissimilar material joining method for joining a plurality of metal members including dissimilar metal members by resistance welding using the rivet of the present invention, and is a first step of preparing the rivet and a steel material. A second member made of a material different from the steel material is superposed on the first member made of the rivet, and the head of the rivet, the shaft portion of the rivet, the second member, and the first member are arranged in this order. The second step of sandwiching the rivet and the first and second members between the first electrode and the second electrode, and energization from the rivet to the first member between the first electrode and the second electrode. In a state where the current flowing through the path becomes a predetermined first current, the first pressurized energization is performed by pushing the tip of the rivet into the second member from the surface side, and the tip of the shaft is made into the first member. The rivet and the first member are predetermined via the first electrode and the second electrode in a state where the tip portion of the shaft portion is in contact with the first member in the third step of abutting. A dissimilar material joining method comprising a fourth step of performing a second pressurized energization in which the rivet is pressed against the first member while energizing with a second current, and welding the tip portion and the first member by resistance spot welding. Is.

In the present invention, in the dissimilar material joining method, the first current is smaller than the second current and may include 0.

According to the present invention, since all of the metal material extruded at the time of joining can be accommodated in the hole of the shaft portion, the second member and the shaft portion of the rivet can be sufficiently replaced, and the joining strength can be increased. Further, the metal material does not scatter on the surface side of the second member at the time of joining.
According to the dissimilar material joining method according to the present invention, the second member can be softened by energizing the energization path from the rivet to the first member in the third step, so that the second member enters the hole of the shaft portion. At the same time, the rivet can be easily pushed into the second member, and the rivet can be firmly pressed against the first member in the fourth step.
Therefore, it is possible to provide a rivet and dissimilar material joining method capable of improving the joining strength and the appearance quality after joining. Further, by using the rivet according to the present invention, it is possible to prevent the factory environment from being contaminated.

FIG. 1 is a cross-sectional view of a rivet according to the present invention. FIG. 2 is a plan view of the rivet. FIG. 3 is a cross-sectional view for explaining the dimensions of each part of the rivet. FIG. 4 is a flowchart for explaining the dissimilar material joining method according to the present invention. FIG. 5 is a cross-sectional view for explaining the second step of the dissimilar material joining method. FIG. 6 is a cross-sectional view for explaining a third step of the dissimilar material joining method. FIG. 7 is a cross-sectional view for explaining the fourth step of the dissimilar material joining method. FIG. 8 is a graph showing changes in the pressurizing current. FIG. 9 is a diagram for explaining a modification of the third step. FIG. 10 is a plan view of a part of the rivet and the transport rail. FIG. 11 is a sectional view taken along line XI-XI in FIG. FIG. 12 is a cross-sectional view showing a modified example of the rivet. FIG. 13 is a cross-sectional view showing a modified example of the rivet. FIG. 14 is a cross-sectional view showing a modified example of the rivet. FIG. 15 is a cross-sectional view showing a modified example of the rivet. FIG. 16 is a cross-sectional view showing a modified example of the rivet. FIG. 17 is a cross-sectional view showing a modified example of the rivet. FIG. 18 is a cross-sectional view showing a modified example of the rivet. FIG. 19 is a cross-sectional view showing a modified example of the rivet. FIG. 20 is a cross-sectional view showing a modified example of the rivet.

Hereinafter, an embodiment of the rivet and dissimilar material joining method according to the present invention will be described in detail with reference to FIGS. 1 to 11.
The rivet 1 shown in FIG. 1 is for joining a plurality of metal members including dissimilar metal members by resistance welding. The plurality of metal members are the first member 2 and the second member 3 which are overlapped with each other in this embodiment. The rivet 1 shown in FIG. 1 penetrates the second member 3 superposed on the first member 2 and is welded to the first member 2 by resistance spot welding. The breaking position in FIG. 1 is the position indicated by the I-I line in FIG. The first member 2 is a plate made of a steel material. The second member 3 is a plate made of an aluminum material. These first member 2 and second member 3 are configured to be a vehicle body part of an automobile, although not shown, by being coupled to each other by a rivet 1. That is, as the first member 2 and the second member 3, those having a thickness such that they become vehicle body parts in a state where both of them are overlapped are used.

The rivet 1 is composed of a head 11 and a shaft portion 12 projecting from the head 11. Examples of the material forming the rivet 1 include steel such as carbon steel for cold heading.
The head 11 is formed in a disk shape. The protruding portion 11a projecting outward from the shaft portion 12 of the head portion 11 is formed so that the thickness is constant over the entire area in the radial direction. Therefore, the annular facing surface 13 of the protruding portion 11a facing the second member 3 is formed flat so as to be parallel to the surface 3a of the second member 3 opposite to the first member 2. ..

A hole 14 formed of a non-through hole extending from the tip of the shaft portion 12 to the inside of the head portion 11 is formed in the shaft center portion of the shaft portion 12. The depth of the hole 14 is the depth at which the vacant space 15 having a predetermined volume is formed inside the head 11. As shown in FIG. 3, the volume of the vacant room 15 is a volume corresponding to the volume of the shaft portion 12 that has entered the second member 3 with the shaft portion 12 penetrating the second member 3. In FIG. 3, a portion of the shaft portion 12 that is inside the second member 3 is shown in FIG. 3 by hatching that is inclined downward to the left.

In the rivet 1 according to this embodiment, the opening side end portion 14a of the hole 14 is formed in a tapered shape. This taper is such that the opening width gradually decreases from the tip of the shaft portion 12 toward the head portion 11. The tip that becomes the outer peripheral edge of the opening side end portion 14a is connected to the outer peripheral surface of the shaft portion 12. The portion where the end portion 14a on the opening side and the outer peripheral surface of the shaft portion 12 intersect is an acute-angled angle.

Here, the dimensions of the rivet 1 and the second member 3 will be described.
The outer diameter D1 of the head 11 is 6.6 mm to 16 mm. Since the head 11 plays a role of holding the second member 3, a larger head 11 is better, but a smaller head 11 is better in consideration of weight reduction. The preferred outer diameter D1 of the head 11 is 6.6 mm to 10 mm.
The height H of the head 11 is 1.1 mm to 32 mm. If the head 11 is too thin, the strength will be insufficient, and if it is too thick, it may interfere with other parts. The preferred height H of the head 11 is 2 mm to 5 mm.

The outer diameter D2 of the shaft portion 12 is 4.6 mm to 8.6 mm. If the shaft diameter of the shaft portion 12 is small, the welding strength may be insufficient. The preferred outer diameter D2 of the shaft portion 12 is 4.6 mm to 8 mm.
The difference between the outer diameter D1 of the head portion 11 and the outer diameter D2 of the shaft portion 12 needs to be at least 2 mm. If this difference is too small, the force for pressing the second member 3 becomes weak, and if it is too large, the head 11 may interfere with other parts. The preferred difference between the outer diameter D1 and the outer diameter D2 is 2 mm to 12 mm.

The length L of the shaft portion 12 is 2 mm to 6.5 mm. The length L of the shaft portion 12 needs to be appropriately installed depending on the thickness of the second member 3. The preferred length L of the shaft portion 12 is 2.5 mm to 5.5 mm.
The inner diameter D3 of the hole 14 is 2.4 mm to 6.4 mm. If the inner diameter of the hole 14 is too small, it becomes necessary to increase the depth of the hole 14 in order to accommodate the material (aluminum material) of the second member 3 that has penetrated, and if the inner diameter is too large, the shaft foot (shaft portion 12) is required. ) May be insufficient in strength. The preferred inner diameter D3 of the hole 14 is 2.4 mm to 5.8 mm.

The depth d of the hole 14 is 2.9 mm to 36.8 mm. If the depth of the hole 14 is too shallow, a part of the second member 3 excluded by the shaft portion 12 penetrating the second member 3 cannot be accommodated. Further, if the depth of the hole 14 is too deep, it is necessary to increase the height of the head 11, which may interfere with other parts. The preferred depth d of the hole 14 is 3.9 mm to 13.1 mm.
The inclination angle α of the opening side end portion 14a can be implemented as long as it is in the range of 10 ° to 80 °, but the inclination angle α is preferably 45 °.
The thickness t of the second member 3 is preferably 0.5 mm to 4 mm. The reason for this is that many materials used in automobiles and on the market have a thickness of 0.5 mm to 4 mm. A more preferable thickness of the second member 3 is 0.6 mm to 2 mm.

Next, a flowchart showing a method of joining dissimilar materials for joining the first member 2 and the second member 3 using the rivet 1 in FIG. 4, and a cross-sectional view and a cross-sectional view showing a state for each step shown in FIGS. 5 to 7. This will be described with reference to the current change graph shown in 8.
As shown in the flowchart of FIG. 4, the dissimilar material joining method according to this embodiment is carried out by the first step S1 to the fourth step S4.

In the first step S1, the rivet 1 is prepared.
In the second step, as shown in FIG. 5, the first member 2 and the second member 3 are superposed on the support base 22 of the pressurizing device 21 in this order, and the rivet is placed at the target fastening position of the second member 3. The shaft portion 12 of 1 is overlapped. At this time, the rivet 1 abuts on the second member 3 in a state of being supported by a clamp (not shown) on the pressing element 23 of the pressurizing device 21. The support base 22 and the presser 23 are configured to function as the first electrode 24a and the second electrode 24b of the resistance spot welder 24.
That is, in the second step, the second member 3 is superposed on the first member 2, and the head portion 11 of the rivet 1, the shaft portion 12 of the rivet 1, the second member 3, and the first member 2 are arranged in this order. , The rivet 11 and the first and second members 2 and 3 are sandwiched between the first electrode 24a and the second electrode 24b. In the first step, no current is passed between the first electrode 24a and the second electrode 24b.

In the third step S3, the current flowing through the energization path from the rivet 1 to the first member 2 between the first electrode 24a and the second electrode 24b is a predetermined first current A (see FIG. 8). At the same time, the pressing element 23 of the pressurizing device 21 is moved toward the second member 3, and the first pressurizing current is performed by pushing the tip end portion of the shaft portion 12 of the rivet 1 into the second member 3 from the surface side.

In the step of pushing the rivet 1, the first current A flows through the second member 3, so that the second member 3 generates heat and softens. Therefore, as shown in FIG. 6, a part 24 of the aluminum material forming the second member 3 melts or plastically flows inside the hole 14 along the tapered surface of the opening side end portion 14a of the hole 14. Get in by. Since a part 25 of the aluminum material is housed in the hole 14 in this way, the shaft portion 12 is surely inserted inside the second member 3 when the rivet 1 is pushed in, and a part of the second member 3 is part of the rivet 1. It replaces the shaft portion 12 of. In the third step S3, the tip portion of the shaft portion 12 is brought into contact with the first member 2 by pushing the rivet 1.

In the fourth step S4, in a state where the tip end portion of the shaft portion 12 of the rivet 1 is in contact with the first member 2, the rivet 1 and the first member 2 are formed via the first electrode 24a and the second electrode 24b. A second pressurized energization is performed in which the rivet 1 is pressed against the first member 2 while being energized with a predetermined second current B. As shown in FIG. 8, the second current B is larger than the first current A in the third step. By performing the second pressure energization in this way, the tip portion of the shaft portion 12 and the first member 2 are welded by resistance spot welding. At this time, the tip portion of the shaft portion 12 of the rivet 1 is melted, so that the shaft portion 12 is fed until the head portion 11 comes into contact with the surface 3a of the second member 3. As the shaft portion 12 melts, a part of the first member 2 and a part of the second member 3 melt, and a nugget 26 is generated centering on the tip portion of the shaft portion 12.
By performing resistance spot welding in this way, the first member 2 and the second member 3 are connected via the rivet 1.

In this dissimilar material joining method, the third step S3 may be performed with the first current set to 0 as shown in FIGS. 9A and 9B. FIG. 9A is a cross-sectional view for explaining the third step, and FIG. 9B is a graph showing a change in the pressurizing current. That is, the third step S3 can be carried out by pushing the shaft portion 12 of the rivet 1 into the second member 3 without supplying power to the first electrode 24a and the second electrode 24b.

According to the rivet 1 according to this embodiment, the shaft portion 12 is such that the metal material (a part 25 of the second member 3) extruded in the third step of pushing the shaft portion 12 into the second member 3 is gathered in one place. It is housed in the hole 14. Therefore, the metal material constituting the second member 3 is in close contact with the outer surface of the shaft portion 12 and the hole wall surface of the hole 14, and the shaft portion 12 is firmly bonded to the second member 3. Further, since a part of the second member 3 and the shaft portion 12 of the rivet 1 are sufficiently replaced in the third step, the fourth member is in a state where the tip of the shaft portion 12 is sufficiently pressed against the first member 2. Resistance spot welding is performed in the process.

Further, since the metal material does not come out to the surface side of the second member 3 at the time of joining, the surface of the second member 3 can be kept in the same state as before the joining.
Therefore, it is possible to provide a rivet and dissimilar material joining method capable of improving the joining strength and the appearance quality after joining. By using the rivet 1 according to this embodiment, it is possible to prevent the factory environment from being contaminated.
Furthermore, since the hole 14 is formed in the shaft portion 12 of the rivet 1 shown in this embodiment, the weight can be reduced as compared with the conventional rivet.

The opening side end portion 14a of the hole 14 of the rivet 1 according to this embodiment is formed in a tapered shape in which the opening width gradually decreases from the tip of the shaft portion 12 toward the head portion 11. Therefore, when the rivet 1 is pushed into the second member 3, the aluminum material can be guided to the hole 14 by plastic flow, so that the shaft portion 12 can be easily pushed into the second member 3, and in the process of pushing. The traveling direction of the shaft portion 12 can be restricted to the thickness direction of the second member 3. Therefore, since the tip of the shaft portion 12 correctly contacts the first member 2, the reliability of resistance spot welding can be improved.

The head portion 11 of the rivet 1 according to this embodiment is formed so that the thickness is constant over the entire area in the radial direction. The head 11 according to this embodiment has a length in which the outer peripheral surface of the head 11 protrudes radially from the outer peripheral surface of the shaft portion 12, unlike the head of a conventional rivet, that is, a head having an annular groove. It can be formed to be short.
Therefore, as shown in FIGS. 10 and 11, the rivet 1 can be easily mounted by using a pair of transport rails 31 passing through the back of the head portion 11 (one side on which the shaft portion 12 is projected). Can be transported.

These transport rails 31 are arranged so as to sandwich the shaft portion 12 from both sides in the radial direction, and are in contact with a part of the outer peripheral surface and a part of the back surface of the head 11 to movably support the head 11. It has a road 31a. The rivet 1 mounted on the transport rail 31 is fed by sliding along the inclined transport rail 31 by its own weight, or is pushed and fed by a pusher (not shown). In the conventional rivet in which the annular groove is formed on the head, the area of the contact portion between the head and the transport rail 31 becomes large, so that the frictional resistance during movement becomes large. Therefore, it has not been easy to transport the conventional rivet by the transport rail 31.

Further, as shown in this embodiment, if the outer peripheral surface of the head portion 11 has a short length protruding in the radial direction from the outer peripheral surface of the shaft portion 12, the mass can be concentrated, so that the mass can be centralized. The operation of handling the rivet 1 can be easily performed, for example, the operation of gripping the rivet 1 with a robot hand (not shown).

(Deformation example of shaft part)
The shaft portion of the rivet can be formed as shown in FIGS. 12 to 15. In these figures, the same or equivalent members as those described with reference to FIGS. 1 to 11 are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate.
The tip of the shaft portion 41 shown in FIG. 12 is formed in a tapered shape in which the forming width gradually decreases toward the tip.
By forming the shaft portion 41 in this way, the resistance when the shaft portion 41 is pushed into the second member 3 is reduced, so that the pushing pressure applied to the rivet 1 at the time of pushing can be reduced.

The tip portion of the shaft portion 42 shown in FIG. 13 has a tapered tapered portion 42a whose forming width gradually decreases toward the tip, and a flat portion 42b formed at the tip portion of the tapered portion 42a. ..
By forming the shaft portion 42 in this way, it is possible to reduce the resistance when the shaft portion 42 is pushed into the second member 3, and the area of the contact portion between the shaft portion 42 and the first member 2 is sufficient. Can be secured. Therefore, the pressing force at the time of pushing can be reduced and the reliability of resistance spot welding can be improved.

The shaft portions 43 and 44 shown in FIGS. 14 and 15 are formed in a cylindrical shape that gradually becomes thinner from the base end on the head portion 11 side toward the tip end. The holes 14 of the cylindrical shaft portions 43 and 44 have a cylindrical surface 45 having a constant hole diameter extending from the tips of the shaft portions 43 and 44 toward the head portion 11 and a shaft portion 43 connected to the cylindrical surface 45. , 44 is formed in a shape having a tapered surface 46 whose hole diameter gradually decreases as the distance from the tip thereof increases.
Since the shaft portions 43, 44 are formed in this way, the volume of the shaft portions 43, 44 pushed into the second member 3 is smaller than that of the shaft portions 12, 41, 42 of each of the above-described examples. Pushing can be done easily.
The contact surface 13 of the head portion 11 shown in FIG. 14 is formed so as to be an inclined tapered surface similar to the shaft portion 43. That is, the head portion 11 shown in FIG. 14 has a flat facing surface 13 facing the surface 3a of the second member 3.

The shaft portion 47 shown in FIG. 16 has an outer peripheral portion and an inner peripheral portion formed in a corrugated cross-sectional shape. More specifically, the outer peripheral portion of the shaft portion 47 is formed so that the large diameter portion 47a and the small diameter portion 47b are alternately arranged in the axial direction. Further, the inner peripheral portion is formed so that the large diameter portion 47c and the small diameter portion 47d are alternately arranged in the axial direction.
The outer peripheral portion of the shaft portion 48 shown in FIG. 17 is formed in a corrugated cross-sectional shape. The outer peripheral portion of the shaft portion 48 is formed so that the large diameter portion 48a and the small diameter portion 48b are alternately arranged in the axial direction.
The shaft portion 49 shown in FIG. 18 has an inner peripheral portion formed in a wave shape in cross section. The inner peripheral portion of the shaft portion 49 is formed so that the large diameter portion 49a and the small diameter portion 49b are alternately arranged in the axial direction.
By forming the shaft portions 47 to 49 in this way, the unevenness formed on the outer peripheral portion and the inner peripheral portion engages with the second member 3, so that the shaft portions 47 to 49 can be more firmly attached to the first member 2. It can be fastened to the second member 3.

(Modified example of rivet head)
The rivet head can be formed as shown in FIGS. 19 and 20. In these figures, the same or equivalent members as those described with reference to FIGS. 1 to 18 are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate.
The head portion 51 shown in FIGS. 19 and 20 has a disc portion 51a protruding outward in the radial direction from the shaft portions 41 and 42, and the outer peripheral portion of the disc portion 51a in the projecting direction of the shaft portions 41 and 42. It is formed by a tubular wall portion 51b made of a projecting cylinder. By providing the tubular wall portion 51b on the head portion 51 in this way, an annular groove 52 is formed between the tubular wall portion 51b and the shaft portions 41 and 42.

The tip of the shaft portion 41 of the rivet 1 shown in FIG. 19 is formed in a tapered shape in which the formation width gradually decreases toward the tip. The hole 14 opens in the center of the taper.
The tip of the shaft portion 42 of the rivet 1 shown in FIG. 20 has a tapered tapered portion 42a whose forming width gradually decreases toward the tip and a flat portion 42b formed at the tip portion of the tapered portion 42a. is doing.

In the rivet 1 shown in FIGS. 19 and 20, when the shaft portions 41 and 42 are pushed into the second member 3, the aluminum material enters the annular groove 52 and the holes 14 of the shaft portions 41 and 42 by plastic flow. Become. Therefore, according to this embodiment, since the aluminum material can be held at two places of the rivet 1, it is possible to obtain a rivet having a higher bonding strength.

In the rivet 1 according to the above-described embodiment, the heads 11 and 51 are formed in a disk shape, and the shaft portions 12, 41 to 44 and 47 to 49 are formed in a cylindrical shape. However, the present invention is not bound by such limitations. That is, the shapes of the heads 11, 51 and the shaft portions 12, 41 to 44, 47 to 49 as viewed from the axial direction may not be circular, but may be polygonal such as a triangle or a quadrangle.

1 ... rivet, 11, 51 ... head, 2 ... first member 2, 3 ... second member, 12, 41 to 44, 47 to 49 ... shaft, 14 ... hole, 14a ... opening side end, 15 ... Vacancy, 51a ... disk part, 51b ... tubular wall part, S1 ... first step, S2 ... second step, S3 ... third step, S4 ... fourth step.

Claims (11)

A rivet that penetrates a second member stacked on a first member and has a head and a shaft portion that are welded to the first member by resistance welding.
The outer diameter of the shaft portion protruding from the head and penetrating the second member is smaller than the outer diameter of the head.
The shaft portion has a hole extending from the tip toward the head portion.
The opening-side end of the hole is formed in a tapered shape in which the opening width gradually decreases from the tip of the shaft portion toward the head portion.
The taper angle, which is the inclination angle of the opening side end of the hole, is 45 ° .
The depth of the hole extending from the tip of the shaft portion toward the head is the depth at which a vacant chamber having a predetermined volume is formed inside the head.
The rivet is characterized in that the volume of the vacant room is a volume corresponding to the volume of the shaft portion that has entered the second member in a state where the shaft portion penetrates the second member . A rivet that penetrates a second member stacked on a first member and has a head and a shaft portion that are welded to the first member by resistance welding.
The outer diameter of the shaft portion protruding from the head and penetrating the second member is smaller than the outer diameter of the head.
The shaft portion has a hole extending from the tip toward the head portion.
The opening-side end of the hole is formed in a tapered shape in which the opening width gradually decreases from the tip of the shaft portion toward the head portion.
The taper angle, which is the inclination angle of the opening side end of the hole, is 45 °.
The head is
A disk portion that protrudes radially outward from the shaft portion ,
A rivet characterized in that it is formed by a cylindrical wall portion made of a cylinder projecting from the outer peripheral portion of the disk portion in the projecting direction of the shaft portion . In the rivet according to claim 1 or 2 .
A rivet characterized in that the hole in the shaft portion is a non-through hole. In the rivet according to any one of claims 1 to 3 .
A rivet having a plate-shaped head having a flat facing surface facing the surface of the second member opposite to the first member. In the rivet according to any one of claim 1, claim 3 or claim 4.
The head is formed in the shape of a disk and is formed in the shape of a disk.
A rivet characterized in that a portion of the head that projects outward in the radial direction from the shaft portion is formed so that the thickness is constant over the entire area in the radial direction. In the rivet according to any one of claims 1 to 5 .
The shaft portion is formed in a cylindrical shape in which the hole is formed in the shaft center portion.
A rivet characterized in that at least one of the outer peripheral portion and the inner peripheral portion of the shaft portion is formed in a cross-sectional wave shape. In the rivet according to any one of claims 1 to 6 .
When the thickness of the second member is 0.6 mm to 2 mm,
The height of the head is 2 mm to 5 mm, and the height is 2 mm to 5 mm.
The outer diameter of the head is 6.6 mm to 10 mm, and the outer diameter is 6.6 mm to 10 mm.
The length of the shaft portion is 2.5 mm to 5.5 mm, and the length thereof is 2.5 mm to 5.5 mm.
The outer diameter of the shaft portion is 4.6 mm to 8 mm, and the outer diameter thereof is 4.6 mm to 8 mm.
The depth of the hole is 3.9 mm to 13.1 mm.
A rivet having an inner diameter of 2.4 mm to 5.8 mm. In the rivet according to any one of claims 1 to 6 .
The outer diameter of the head is larger than the outer diameter of the shaft,
A rivet characterized in that the difference between the outer diameter of the head portion and the outer diameter of the shaft portion is 2 mm to 12 mm. In the rivet according to any one of claims 1 to 8 .
The inside of the hole is a rivet characterized in that the shaft portion is filled with a metal material in a state of being welded to the first member by resistance welding. A dissimilar material joining method for joining a plurality of metal members including dissimilar metal members by resistance welding using the rivet according to any one of claims 1 to 9 .
The first step of preparing the rivet and
A second member made of a material different from the steel material is superposed on the first member made of a steel material, and the head of the rivet, the shaft portion of the rivet, the second member, and the first member are arranged in this order. , The second step of sandwiching the rivet and the first and second members between the first electrode and the second electrode,
The tip of the rivet is surfaced on the second member in a state where the current flowing in the energization path from the rivet to the first member between the first electrode and the second electrode is a predetermined first current. A part of the material forming the second member by performing the first pressurizing current pushed in from the side is a tapered opening side end portion in which the taper angle of the hole formed in the shaft portion of the rivet is 45 °. A third step of bringing the tip of the shaft into contact with the first member so that the tip of the shaft can be melted or plastically flowed into the hole along the tapered surface and accommodated in the hole.
While the tip of the shaft portion is in contact with the first member, the rivet and the first member are energized with a predetermined second current via the first electrode and the second electrode. A dissimilar material joining method comprising a fourth step of performing a second pressurized energization in which the rivet is pressed against the first member and welding the tip portion and the first member by resistance spot welding. In the dissimilar material joining method according to claim 10 ,
The dissimilar material joining method, wherein the first current is smaller than the second current and contains 0.

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