JPH10205510A - Rivet fastening method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable caulking with low load by pinching and pressing a rivet inserted through a plurality of work pieces between a pair of electrodes, by softening the rivet by resistance generated heat of the rivet itself by electrification, and by caulking the end. SOLUTION: A headed rivet 1 is inserted through holes Wa of two work pieces W so that the head part 1a on the upper end may be seated on the work piece W on the upper side, the rivet 1 is pinched between electrodes 4, 5 of a welding gun and pressed, and the rivet is electrified. The tips of the electrodes 4, 5 are formed into recessed curved surfaces 4a, 5a, the head part 1a is brought in surface-contact with the curved surface 4a, and the lower end of the rivet 1 is brought in linear-contact with the curved surface 5a. Accordingly, the current density of the lower end of the rivet 1 is drastically increased in comparison with the head part 1a and instantaneously heated to the high temperature. Therefore, the lower end of the rivet 1 is softened and caulked by low pressing force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a riveting method for joining a plurality of works using rivets.

[0002]

2. Description of the Related Art Riveting is performed by inserting a rivet into a hole formed in a work and then caulking an end of the rivet. And the caulking of rivets in the factory,
Conventionally, this is performed using a press machine (Japanese Patent Laid-Open No. 1-2
No. 41346).

[0003]

In the case of using a press machine as in the above conventional example, noise and vibration become problems,
In addition, when the work is a soft material such as a thin plate or aluminum, the work is easily deformed by warping or distortion due to a caulking force.

[0004] In view of the above, it is an object of the present invention to provide a riveting method capable of caulking a rivet with a low load without using a press machine.

[0005]

Means for Solving the Problems In order to solve the above problems,
The present invention relates to a riveting method for joining a plurality of works by using rivets, wherein a rivet inserted through the plurality of works is sandwiched between a pair of electrodes, and a current is applied in a pressurized state. The rivet is softened by resistance heating, and the end of the rivet is swaged.

According to the present invention, the rivet is self-heated and softened by the Joule heat generated by energization, and the rivet can be caulked with a low load. Therefore, even if the work is a soft material such as a thin plate or aluminum, the work is not deformed such as warpage or distortion, and noise and vibration problems can be solved. Also, since the caulking load is reduced, the rivet can be caulked using a normal spot welding machine having a pair of electrodes, and special equipment is not required, which is advantageous in cost. .

The rivet may be a pin having no head or a rivet having a head at one end. In the former rivet, both ends are swaged, and in the latter rivet, the other end opposite to the head is swaged.

When each electrode has a concave curved surface at its tip, the end of the rivet to be caulked comes into line contact with the concave curved surface, and the current density increases due to the decrease in the contact area, so that the rivet can be bent. This is advantageous because the end portion generates heat with good responsiveness.

[0009]

FIG. 1 shows two works W, W
Of the riveting operation in which the rivets 1 are joined by a plurality of rivets 1. The spot welding gun 3 mounted on the tip of the robot arm 2 is sequentially moved to the mounting position of each rivet 1, and the rivet 1 is caulked. To do.

The details are as shown in FIG.
As shown in FIG. 2A, a rivet 1 with a head is inserted into a hole Wa formed in the two works W, W such that the head 1a at the upper end thereof is seated on the work W on the upper side. The welding gun 3 is closed by the operation of the pressurizing cylinder 3a, and as shown in FIG. 2 (B), the rivet 1 is sandwiched between a pair of upper and lower electrodes 4 and 5 of the welding gun 3 and pressed from above and below. The rivet 1 is energized in this state.

Here, the tips of the upper and lower electrodes 4 and 5 are formed on concave curved surfaces 4a and 5a.
While a is in surface contact with the concave curved surface 4a of the upper electrode 4, the lower end of the rivet 1 is in line contact with the concave curved surface 5a of the lower electrode 4. Therefore, the current density at the lower end of the rivet 1 is significantly increased as compared with the current density at the head 1a, and the lower end of the rivet 1 instantaneously generates heat to a high temperature when energized. Then, the lower end of the rivet 1 is softened by the heat generation, and the lower end of the rivet 1 is swaged by the pressing force as shown in FIG.

In the above-described embodiment, the rivet 1 is provided with a head, but a rivet 1 having a headless pin shape as shown in FIG. 3 may be used. In this case, the work W,
As shown in FIG. 3A, the rivet 1 is inserted into the hole Wa of the W by light press-fitting so that the rivet 1 does not fall off. Then, as shown in FIG. Electric current is supplied while being pressed between the electrodes 4 and 5. in this case,
Both ends of the rivet 1 are concave curved surfaces 4a of the electrodes 4 and 5, respectively.
Due to the line contact with 5a, both ends of the rivet 1 are instantaneously heated to a high temperature and softened, and both ends of the rivet 1 are swaged by the pressing force as shown in FIG. In this embodiment, the rivet 1 has a hollow pin shape, but may have a solid pin shape.

Two aluminum alloy plates having a thickness of 2.0 mm (A
5182-0) with an outer diameter of 8.0 mm, an inner diameter of 4.5 mm,
12mm long hollow pin-shaped aluminum alloy (A505
When riveting was performed using the rivet of 2), the load required for caulking the rivet was 2000 when no current was supplied.
Although it was kgf, it became 300 kgf when energized at 20 KA and 10 cycles (1 cycle = 1/50 Hz).

Further, two Zn steel plates having a thickness of 2.3 mm are made of steel having an outer diameter of 6.0 mm and a length of 12 mm (S35C).
When riveting with rivets, the load required for caulking the rivets is 3000 kg when no power is supplied.
f, but 300k at 9KA, 10 cycles
gf.

The aluminum rivet has a low electric resistance and therefore needs to have a high current value. However, since the heat conduction and heat dissipation are good, the heat effect on the workpiece is lower than when a steel rivet is used. It was also confirmed that the number was reduced.

In the above embodiment, the spot welding gun 3 is used as a caulking device, but a stationary spot welding machine may be used.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a situation of a riveting operation according to the present invention.

2 (A), 2 (B), 2 (C) are views showing steps of caulking a rivet with a head.

FIGS. 3A, 3B, and 3C show steps of caulking a headless rivet. FIGS.

[Explanation of symbols]

 W Work 1 Rivets 3 Spot welding gun 4,5 Electrode 4a, 5a Concave curved surface

Claims (5)

[Claims] 1. A riveting method for joining a plurality of workpieces using rivets, wherein a rivet inserted through the plurality of workpieces is sandwiched between a pair of electrodes and energized in a pressurized state. Riveting method by softening the rivet by resistance heat generation and caulking the end of the rivet. 2. The riveting method according to claim 1, wherein a rivet having a pin shape without a head is used, and both ends of the rivet are crimped. 3. The riveting method according to claim 1, wherein a rivet having a head having a head at one end is used, and the other end of the rivet is swaged. 4. The riveting method according to claim 1, wherein each of the electrodes has a tip formed into a concave curved surface. 5. The riveting method according to claim 1, wherein the pair of electrodes is an electrode attached to a spot welding machine.