JP2008303978A - Impact rivet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impact rivet not only being easy to disassemble after fastened, easy to separate joined materials and effective in recycling, but also having high joint strength and a good appearance on both sides of a joint portion, and to provide a joint method using the same. <P>SOLUTION: The impact rivet 1 comprises a rivet head portion 1a and a rivet shaft portion 1b. A die 3 is arranged on the lower face side of an overlapped body of the joined materials 4, 5 to be joined to each other. When the impact rivet 1 is pneumatically driven from the upper side of the overlapped body, the rivet head portion 1a passes through the overlapped body. On the other hand, a through-hole 2a is formed in a rivet receiving portion 2 arranged in a recess 3a of the die 3, and a recess 2c is formed to be opened toward the back face side. When the front end of the rivet shaft portion 1b collides with the die 3, it is deformed along an inner shape formed by the recess 2c and a locking step portion 2b of the rivet receiving portion to close the recess 2c for completion of riveting. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an impact rivet (self-piercing rivet) used for stacking and fastening materials to be joined such as metal plates and a joining method thereof, and particularly provides an impact rivet that can be easily recycled.

  Housings for home appliances and bodies such as vehicles are made of metal plates such as aluminum alloys. Joining these metal plates is a mechanical fastener method that uses self-drilling rivets to replace resistance spot welding. Has been proposed (see, for example, Patent Document 1).

  Patent Document 1 discloses a method of joining an aluminum alloy material by a self-piercing rivet, and the self-piercing rivet is directed downward from the upper surface of the laminated body of aluminum alloy plates stacked for joining. Type in a punch. The self-piercing rivet is made of, for example, mild steel, and its shape before driving is constituted by a rivet head and a rivet shaft. The shape of the rivet head has a flat top surface and exhibits an inverted frustoconical shape. On the other hand, the shape of the rivet shaft portion has a cylindrical shape in which the cylindrical portion is cut out from the lower end surface. Then, a die is disposed on the lower surface of the stack of aluminum alloy plates to be joined, and a self-piercing rivet is driven by a punch from above the stack, and the shaft portion of the self-piercing rivet is placed at the bottom of the die by the die. The self-drilling rivet locks the aluminum alloy plates together by being pushed and expanded by an upward projection provided at the center. At this time, the aluminum alloy plate on the die side plastically flows as the rivets are driven and expanded, and is expanded inside the die as the shaft portion is expanded. The joint joined by the self-piercing rivet has a static strength equivalent to that of the joint by resistance spot welding.

  In Patent Document 1, a JIS 6000 series aluminum alloy is used as a component system of an aluminum alloy material that is a material to be joined, the materials to be joined made of the aluminum alloy material are stacked, and these are joined by self-piercing rivets. At that time, as the self-piercing rivet is driven, severe plastic flow is caused in a specific part of the material to be joined, and as a result, a fine crack is generated in the part. In view of this, there has also been proposed a method of joining so as not to cause fine cracks after the self-piercing rivet is driven (see Patent Document 2).

JP 11-33664 A Japanese Patent No. 3830421

  However, the conventional rivet fastening method is intended for permanent fastening, and does not consider recycling of the joining material after dismantling. That is, in the conventional self-piercing rivet, the joining material is very difficult to disassemble due to the rivet shaft end that is expanded after the fastening. Further, the expanded rivet shaft end significantly deteriorates the appearance of the joint surface. The present invention has been made in view of such problems, and it is easy to disassemble the rivet after fastening, it is easy to separate the joining material, and not only is effective for recycling, but also high joining strength is obtained, and the joining portion An object of the present invention is to provide an impact rivet capable of improving the aesthetics of both sides and a joining method using the impact rivet.

  For this reason, the present invention superimposes a plurality of materials to be joined, disposes a die on the back side of a desired joining position, and strikes a rivet from the front side to penetrate a rivet shaft through the material to be joined. In a self-drilling type impact rivet that collides a rivet shaft with a die so as to squeeze the shaft end and fasten the material to be joined, the rivet comprises a pressing head and a rivet shaft. And a rivet bearing portion in which a through hole of the rivet shaft is formed and a recess opening toward the back side is formed, and the rivet receiving portion is formed when the end portion of the rivet shaft collides with a die. The first feature is that the recess is deformed following the shape of the recess, and the recess is closed and caulked. A second feature is that a locking step portion is provided between the through hole and the recess of the rivet bearing portion. Furthermore, the third feature is that the rivet is struck by air pressure. Furthermore, a fourth feature is that the die is provided with a collision surface on which the punched workpiece remains when the rivet shaft is crushed and expanded by the collision surface of the die bottom.

The present invention has the following advantages.
(1) It is easy to disassemble the rivet after fastening, it is easy to separate the materials to be joined, and it is effective for recycling.
(2) High bonding strength can be obtained, and the appearance on both sides of the bonded portion can be improved.

  Next, embodiments of the present invention will be described in detail with reference to examples shown in the drawings. 1 and 2 are views showing a method of joining aluminum plate materials by means of impact rivets according to the present invention. FIG. 1 is a cross-sectional view showing a state before rivets are driven into a material to be joined, and FIG. FIG. 3 is a schematic view of a driving apparatus according to the present invention, FIG. 4 is a schematic view showing a tensile test, and FIG. 5 is a test result of rivet fastening strength by a normal caulking operation. FIG. 6 is a graph showing the fastening strength of the impact rivet according to the present invention, and FIG. 7 is a graph showing the punching test result of the impact rivet after fastening.

  As shown in FIGS. 1 and 2, the impact rivet 1 according to the present invention is made of, for example, aluminum, and the shape before driving is composed of a rivet head 1a and a rivet shaft portion 1b. The shape of the rivet head 1a has a cylindrical shape with a flat top surface, and the shape of the rivet shaft portion 1b has a cylindrical shape having a smaller diameter than the rivet head 1a. When the die 3 is disposed on the lower surface side of the stacked body of the materials 4 and 5 to be bonded and the impact rivet 1 is driven by air pressure from above the stacked body, the rivet head 1a penetrates the stacked body. To do. On the other hand, the rivet receiving portion 2 disposed in the recess 3a of the die 3 is formed with a through hole 2a and a recess 2c that opens toward the back side, and the tip of the rivet shaft portion 1b. Is collided with the inner shape formed by the recess 2c of the rivet receiving portion 2 and the locking step portion 2b when it collides with the die 3, and the recess 2c is closed and caulked.

  That is, as shown in FIG. 1, first, the two aluminum plate members 4 and 5 as the materials to be joined are overlapped and held horizontally by an appropriate means such as a clamp. Then, the die 3 is arranged on the back side of the desired joining position, and the rivet 1 is struck from the top side thereof so that the rivet shaft 1b penetrates the workpieces 4 and 5, and at the same time the rivet shaft 1b collides with the die 3. By doing so, the shaft end is crushed, and the aluminum plate members 4 and 5 are fastened by the rivet 1 and the rivet receiving portion 2 (shown in FIG. 2).

  As shown in FIG. 2, the aluminum plates 4 and 5 are caulked by the impact rivet 1. That is, the tip of the rivet shaft 1 b is crushed and expanded by the collision surface 3 b provided at the bottom of the die 3 and deformed in the recess 2 c of the rivet receiving portion 2. The punched plate accumulates on the collision surface 3b. However, since the tip part of the crushed rivet shaft part 1b is entirely contained in the recess 2c of the rivet receiving part 2, it exhibits a good aesthetic appearance.

(Experimental example)
A high speed punching experiment was performed using the apparatus shown in FIG. Aluminum plate materials 4 and 5 having a thickness of 2 mm are stacked, the axial length of the impact rivet 1 (indicated by L1 in the figure), the recess 2b of the rivet receiving portion 2 (indicated by L2 in the figure), and the collision surface of the die 3 The dimensions of the inner diameter and depth (indicated by D1 and D2 in the figure) were changed. Here, the outer diameter of the rivet head 1a is 7.5 mm, the height is 5 mm, the shaft diameter of the rivet shaft 1 b is 3.8 mm, the outer diameter of the rivet receiving portion 2 is 7.5 mm, the height is 5 mm, and the diameter of the rivet through hole 2 a is 4 mm. The diameter of the recess is 4.5 mm, and the diameter of the recess of the die 3 is 8 mm. The impact rivet 1 was fired from the launch tube 6 at a speed of 110 m / s to 120 m / s by air pressure. Table 1 shows the experimental conditions.

  Members were fastened based on each experimental condition shown in Table 1, and a tensile test (fastening strength test) shown in FIG. 4 was performed. At that time, as a comparative example, rivet fastening by ordinary caulking was also performed. The rivet for caulking has a rivet head outer diameter of 7.5 mm, a height of 5 mm, a shaft diameter of the rivet shaft 1b of 3.8 mm, and a shaft length of 7.5 mm. The test result of normal caulking is shown in the graph of FIG. Moreover, the test result of an impact rivet is shown in the graph of FIG. As a result, it was found that the average breaking load due to tension is 133.32 kgf in normal caulking, but high strength of 178 kgf on average can be obtained by impact rivets.

  Next, several samples were extracted from the test piece after fastening, and a punching strength test (disassembly test) for disassembly was performed. In the test, the rivet shaft portion 1b portion was pushed out from the rivet receiving portion 2 side using a pressing device, and the load was measured. The result is shown in the graph of FIG. As can be seen from this graph, it can be seen that a punching force larger than the fastening strength is required (the sample No. 7 is considered to be insufficiently fastened). From this, it was found that the fastening body is excellent also in the fastening force in the direction perpendicular to the rivet shaft. Moreover, it turned out that the aluminum plate materials 4 and 5 after disassembly have little deformation and are useful for recycling.

  In the description of the above embodiment, the bonded material is two aluminum alloy materials. However, the bonded material is not limited to this, and there are two or more bonded materials, or other metal or plastic. Needless to say, it is also useful for materials and the like.

It is sectional drawing which shows the state before driving the rivet which concerns on this invention into a to-be-joined material. It is sectional drawing which shows the state after driving a rivet into a to-be-joined material. It is the schematic of the driving device which concerns on this invention. It is a schematic diagram which shows a tension test. It is a graph which shows the test result of the rivet fastening strength by normal caulking work. It is a graph which shows the fastening strength of the impact rivet which concerns on this invention. It is a graph which shows the punching test result (disassembly test result) of the impact rivet after fastening.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Impact rivet 1a Rivet head 1b Rivet shaft part 2 Rivet receiving part 2a Rivet shaft through-hole 2b Locking step part 2c Opening recess 3 Die 3a Dice recess 3b Colliding surface 4 Aluminum plate material (joined material)
5 Aluminum plate (material to be joined)
6 Launcher

Claims (4)

  A plurality of materials to be joined are overlapped, a die is placed on the back side of the desired joining position, and a rivet is pressed from the front side so that the rivet shaft penetrates the material to be joined, and at the same time the rivet shaft collides with the die. In the self-drilling type impact rivet in which the shaft end is crushed and the material to be joined is fastened, the rivet includes a rivet body including a pressing head and a rivet shaft, and the rivet shaft. The rivet bearing portion is formed with a through hole and a recess that opens toward the back side. When the end of the rivet shaft collides with the die, it follows the shape of the recess of the rivet receiving portion. The impact rivet is characterized in that it is deformed to close and close the recess.   2. The impact rivet according to claim 1, wherein a locking step portion is provided between the through hole of the rivet bearing portion and the opening recess.   3. A joining method using an impact rivet according to claim 1, wherein the rivet is struck by air pressure.   4. The collision surface on which the punched material remains when the rivet shaft is crushed and expanded by the collision surface at the bottom of the die. 5. A joining method using the impact rivet described in Crab.

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