JPS639917B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for joining a boss to a plate material, and particularly to a resistance welding method for a boss suitable for cases where a beautiful appearance of the surface of the plate material is required, such as the front panel of various devices. be.

Conventionally, press-fitting or resistance welding have been mainly used as methods for joining bosses to plate materials.

The common method of joining by press-fitting is to create a through-hole in the plate material and press-fit a boss into the through-hole, but this method is inferior in strength to joining by welding, and it is difficult to use products with press-fitted bosses for long periods of time. Otherwise, marks may appear on the painted surface, which is also an aesthetic problem.

On the other hand, resistance welding has superior strength and a better finish than press-fitting, so it can be said to be particularly suitable for joining bosses to plate materials that require good surface appearance.

The conventional resistance welding method will be explained below with reference to FIG.

In the resistance welding method, in which a current is passed through two or more metals in contact and the metals are melted and joined by the generated Joule heat, the current is concentrated in one part and the generation of Joule heat is locally increased. It is necessary to melt the metal by Generally, when joining a boss and a plate material, projection welding is used in which a protrusion 2 is provided on the joining surface side of the boss 1, as shown in FIG. Figure a shows an example in which the protrusion 2 is formed by drilling the joint surface side of the boss 1 into a spherical shape, and Figure b shows an example in which the protrusion part 2 is formed by providing a ring-shaped wall on the joint surface side of the boss 1. This is an example. The boss 1 provided with the protrusion 2 on the joint surface side as described above is
A first electrode 4 and a second electrode 5 are arranged on the plate material 3.
A current is passed under pressure. Therefore, the boss 1 and the plate material 5 are melted and joined near the protrusion 2.

However, in the above-mentioned resistance welding method, it is difficult to form the protrusion 2 of the boss 1, and if the protrusion 2 is not formed uniformly, the current will not flow uniformly to the protrusion 2, resulting in incomplete welding. It becomes a junction. Also, since no positioning means is provided, the boss 1 can be moved to the plate 3.
requires a welding jig for positioning. Since the contact area between the plate material 3 and the second electrode 5 is large, there is a possibility that the contact may occur unevenly, and in that case, current flow may be unevenly distributed and the boss 1 and the plate material 3 may not be uniformly joined.

The present invention has been made in view of the above-mentioned drawbacks, and it is easy to process the boss, the boss and the plate material can be reliably joined without using a positioning jig, and the boss can be reliably joined to the plate material after the boss is joined. The present invention provides a boss resistance welding method that does not impair the beauty of the plate material.

Therefore, in the present invention, the above object is achieved by forming a recess part halfway in the thickness direction of the plate material and providing a guide protruding from the center of the joint surface of the boss. That is, the guide is shaped to fit into the recess and has a length shorter than the depth of the recess. Therefore, not only is the position of the boss determined by fitting the guide into the recess, but the tip of the guide and the plate come into contact with each other with a gap, so the welding current is concentrated on the narrow joint surface. As a result, the same effect as when a ring-shaped protrusion is formed on the boss can be obtained. Further, by forming the recessed portion by pressing, the above object can be achieved even more reliably. That is, by forming the recessed part by pressing, the edge of the recessed part becomes a sagging surface, so that the joint area between the plate material and the joint surface is further reduced, and the same effect as that of forming a narrower ring-shaped protrusion can be obtained. On the other hand, on the back side of the plate material where the concave portion is formed, a slight bulge is generated due to the pressing, thereby ensuring reliable contact with the electrode.

Embodiments of the present invention will be described in detail below with reference to FIGS. 2 to 4.

6 is a cylindrical boss with parts etc. (not shown)
A female threaded portion 7 for screwing is provided therethrough. A joint surface 8 and a guide 9 are formed on one end surface of the boss 6, and the guide 9 is provided to protrude from the center of the joint surface 8.

10 is a plate material in which a recess 11 is bored halfway in the thickness direction. As shown in FIGS. 4a and 4b, the recess 11 is formed by pressing the plate 10 in the direction of arrow X with a punch 13 while the plate 10 is placed on a fixing table 12. Therefore, a sagging surface 14 is generated at the periphery of the recess 11, and the surface of the plate material 10 corresponding to the back side of the recess 11 is slightly raised to form a contact portion 15. The guide 9 described above is shaped to fit into the recess 11, and its length is shorter than the depth of the recess 11.

As shown in FIG. 3, the boss 6 described above is placed at a predetermined position on the plate 10 by fitting its guide 9 into the recess 11, and then the boss 6 and the plate 10 are placed in a predetermined position.
Since current is applied while both sides of the plate are pressurized by the first electrode 16 and the second electrode 17, the plate material 10 is welded to the plate material 10. In this case, as described above, the length of the guide 9 is shorter than the depth of the recess 11, and there is a gap t between the tip of the guide 9 and the plate 10, so the current passes only through the joint surface 8 of the boss 6. As a result, the same effect as when a ring-shaped protrusion is formed on the boss 6 can be obtained. Also, the recess 11
Since a sagging surface 14 is formed on the bonding surface 8,
The contact area between the plate member 10 and the plate material 10 is further reduced, and the current density is increased, making it easier to melt the metal near the joint surface 8. Furthermore, since the raised contact portion 15 is formed on the plate 10 by pressing, the electrical connection between the plate 10 and the second electrode 17 is reliably established. Therefore, the boss 6 can always be welded to the plate material 10 in a good condition.
Note that this bulge on the contact portion 15 is melted by the current when welding the boss 6 described above, and the first electrode 1
Due to the pressing force between the electrode 6 and the second electrode 17, it will eventually become flush with the plate material 10, and there will be no problem in appearance.

In order to facilitate understanding of the present invention, one test example will be described below.

1.2m/m thick, material SPCC plate material 10, inner diameter
A recess 11 with a diameter of 4φ and a depth of 0.5m/m is bored by a press, and a guide 9 with an outer diameter of 4φ and a height of 0.3m/m and a female threaded part 7 with a nominal diameter of 3φ and an outer diameter of 3φ and a height of 7m/m are formed. When the boss 6 made of a material equivalent to S20C was welded and joined by the method described above and a destructive test was performed, the plate 11 was broken because the bond between the plate 11 and the boss 6 was strong. Also, the contact portion 1 formed by pressing
The height of the contact portion 15 was approximately 0.1 m/m, and the swell of the contact portion 15 disappeared after contact with the boss 6.

As described above, according to the resistance welding method of the boss according to the present invention, it is sufficient to process the joint surface of the boss by cutting the outer peripheral surface of the boss using a lathe operation, for example, to form a guide. can be formed accurately with simple work. Positioning on the plate material can be accomplished by simply inserting the guide into the recess. Even if a screw hole is previously drilled through the boss, the appearance will not be spoiled. Contact between the plate material and the electrode can be made reliably through the contact portion. Since the boss is connected to the plate material at the outer periphery, it has a structure that is strong against the torque generated when attaching screws. As mentioned above, it has great effects.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the conventional projection welding method, where a shows a case in which a protrusion is formed by drilling a spherical hole on the joint surface side of the boss, and b shows a ring-shaped wall on the joint surface side of the boss. The figure shows a case in which it is formed in a protruding manner. 2 to 4 show embodiments of the present invention, FIG. 2 is a perspective view showing the engagement relationship between the boss and the plate material, and FIG. 3 is a perspective view showing the engagement relationship between the boss and the plate material. , a cross-sectional view showing a state in which pressure is applied from both sides by the first electrode and the second electrode, FIG. The previous cross-sectional view, b, shows a cross-sectional view of the plate material in which the recesses have been formed. 6...Boss, 8...Joint surface, 9...Guide, 10...Plate material, 11...Recess.

Claims (1)

[Scope of Claims] 1. A recess is bored halfway through the thickness of the plate material, and for the boss, a guide having a shape that is shorter than the depth of the recess and fits into the recess is inserted from the joint surface with the plate material. protrudingly provided, and fitting the guide into the recess;
A method for resistance welding a boss, characterized in that a welding current is supplied while the plate material and the joint surface of the boss are in contact with each other. 2. The boss resistance welding method according to claim 1, wherein the concave portion of the plate material is formed by pressing.