JPS60213371A - Binding method of painted steel sheets - Google Patents

Abstract

PURPOSE:To weld and bind a painted steel sheet and steel sheet without spoiling the appearance by providing projecting parts which project to the painted film surface side to the painted steel sheet, peeling the painted film at the peak part thereof, bringing the painted steel sheet into contact with the other steel sheet and passing electric current through the contact parts thereof. CONSTITUTION:Plural pairs of the projecting parts 7, 8 projecting to painted film 6 surface side are formed to a flange part 2a formed in a bent state to the rear of a main box 2 of a refrigerator consisting of the painted steel sheet in the stage of binding the box 2 and a back plate 3. The painted film 6 at the peak part thereof is peeled. The sheet 3 is then superposed on the flange part 2 to bring the above-mentioned projecting parts 7, 8 into contact with the film 6 surface side of the sheet 3. Electrodes 9, 10 are touched thereafter to the side of the parts 7, 8 opposite from the film 6 and a voltage is impressed between both electrodes; at the same time the sheet 3 is pressed by a pressing member 11. The current is then passed between the contact parts A and B of the parts 7, 8 and the sheet 3 and a welding phenomenon is generated in the parts A, B; in addition, the projecting parts 7, 8 are collapsed by which the box 2 and the sheet 3 are surely bound.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for joining coated steel sheets formed by forming a coating film on one side.

[Technical background of the invention]

For example, when manufacturing an outer box for a refrigerator, in order to omit the painting process, it is often manufactured from a painted steel plate, a so-called colored steel plate, which has a coating film formed on one side in advance. However, since this colored steel plate is coated with a coating and lacks electrical conductivity in the thickness direction, spot welding is impossible, and it has generally been necessary to join them by screwing or caulking.

[Problems with background technology]

However, the above-mentioned method has a problem in that the screw heads are exposed on the surface of the outer case and the holes formed for caulking are exposed, which impairs the appearance.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for joining painted steel plates that can prevent damage to the appearance.

[Summary of the invention]

The present invention provides a coated steel plate with a protrusion that protrudes toward the coating surface side, peels off the coating on the top of the protrusion, and places the top and another steel plate in contact with each other at the opposing portion. The coated steel plate and the steel plate are welded to each other by passing an electric current through the steel plate.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

First, FIG. 1 shows the whole refrigerator, where 1 is an outer box, which is made up of a main box 2 whose back and front sides are open, and a back plate 3 joined to the open back side. Reference numerals 4 and 5 denote a freezer compartment and a refrigerator compartment which are provided on the open front of the outer box 1 so as to be openable and closable. Both the main box 2 and the back plate 5 constituting the outer box 1 are made of painted steel plates with a coating film 6 (see Fig. 4) formed on one surface (outer surface) in advance, and the back plate 5 is made of painted steel plate as shown in Fig. 4. As shown in FIG. 2, it is intermittently welded to a flange portion 2a bent and formed on the back surface of the main body box 2 by the method described below.

That is, first, a plurality of pairs of protrusions 7 and 8 protruding toward the coating @6 side are formed on the 7 rank part 2a on the back side of the main body box 2, and then,
The coating film 6 on the top of each projection 7, 8 is peeled off. After this, electrodes 9 and 10 are applied to the anti-paint film 6 surface of each protrusion 7 and 8, and 7
The back plate 3 is stacked on the rank part 2a so that the side of the back plate 5 opposite to the coating film 6 and each protrusion 7°8 are in contact with each other, and the presser member 11
Then press the back plate 5 (see FIGS. 2 and 5). Then, a voltage is applied between the electrodes 9 and 10 while pressurizing the presser member 11 and the electrodes 9 and 10 with the back plate 5 and flange portion 2a overlapped. As a result, not only the gap between the electrodes 9 and 10 of the seventh rank portion 2a, but also the gap between the protrusion 7 and the back plate 5
Since a large current flows through the contact area A between the back plate 5 and the protrusion 8 and the back plate 3, the protrusion parts 7 and 8 and their surroundings are not softened by Joule heat. At the same time, a welding phenomenon occurs at the opposing parts A and B, and the presser member 11 and both electrodes 9
, 10, the protrusions 7, 8 are crushed. Thereafter, by removing the holding member 11 and both electrodes 9 and 10, a bonded state as shown in FIG. 4 is obtained.

According to the above-described joining method, the coating film 6 on the tops of the protrusions 9 and 10 is separated from each other to obtain conductivity, so even if it is a painted plate, welding by electric current, which could not be achieved conventionally, is ensured. can be done. Therefore, this method is different from the conventional method using screws or caulking.

Since the screw heads and the caulking holes are not exposed to the outside, it is possible to reliably prevent the appearance of the outer box 1 from being damaged.

Note that the present invention is not limited to the embodiments described above and shown in the drawings; for example, the steel plate on the side where no protrusion is provided is not limited to a painted steel plate, but may also be a normal steel plate without a coating film. good. Furthermore, the protrusions do not necessarily need to be provided in pairs; - one electrode may be provided at each welding location, with one electrode in contact with the painted steel plate on the protrusion side, and the other electrode in contact with the other steel plate side. In other words, the current may be passed through the contact portion between the top of the protrusion and the other steel plate.

〔Effect of the invention〕

As described above, the present invention provides a protrusion on a painted steel plate, peels off the coating on the top of the protrusion, and then flows an electric current through the contact portion with the top of the protrusion and another steel plate in contact with each other. It is characterized by the fact that it is welded together, which has the effect of allowing painted steel plates to be joined without damaging the appearance with screw heads or caulking holes.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a perspective view of the entire refrigerator from the back, Fig. 2 is an enlarged sectional view of the main parts showing the joining process, and Fig. 6 is the middle part of Fig. 2. FIG. 4 is an enlarged sectional view taken along the line, and FIG. 4 is an enlarged sectional view showing a coupled state. In the drawings, 2 is a main box, 3 is a back plate, 6 is a coating film, 7.8 is a protrusion, 9 and 10 are electrodes, and A and B are contact parts.

Claims (1)

[Claims] 1. A device for joining a coated steel plate with a coating film formed on one side and a steel plate, wherein the coated steel plate is provided with a protrusion that protrudes toward the coating film side, and at the top of the protrusion. By peeling off the coating film, placing the top part of the coating film in contact with the steel plate, and passing an electric current through the contact part,
A method for joining painted steel plates, characterized in that the painted steel plates and the steel plates are welded to each other.