JPS62110878A - Spot welding method for laminate steel plate - Google Patents

Abstract

PURPOSE:To improve the welding quality of a laminate steel plate by melting an insulating layer by making a small current flow to the laminate steel plate, and thereafter, generating a nugget by making a medium current flow to the laminate steel plate, and thereafter, welding the laminate steel plate to other base metal by a large current. CONSTITUTION:A short circuit clamp member 18 is installed to the surface and the reverse side of a laminate steel plate 16, electrodes 20, 22 are pushed and pressed against the surface and the reverse side to be welded of the steel plate 16, respectively, and also an insulating layer 14 between the electrodes 20, 22 is melted by making a small current flow. Subsequently, the insulating layer 14 is eliminated by making a medium current flow so that a nugget 24 is formed between the electrodes 20, 22, and also the nugget 24 is formed between steel plates 10, 12. Thereafter, the steel plates 10 12 are welded to a base metal 26 by making a large current flow to the laminate steel plate 16, therefore, it can be prevented that a crack is generated in the laminate steel plate at the time of spot welding, and said plate is not welded completely to the base metal 26, and it is possible to contribute to an improvement of the welding quality.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for spot welding laminated steel plates, and in particular to a method for spot welding laminated steel plates with a sandwich-inch structure having an insulating layer between the steel plates. The present invention relates to a spot welding method for laminated steel plates suitable for.

[Conventional technology]

Conventionally, when welding a laminated steel plate to another steel plate by spot welding, even if an electrode is pressed against the laminated steel plate and energized, the current-carrying circuit will be interrupted by the insulating layer. The laminated steel plate and other steel plates were welded together through this hole. However, this method requires drilling holes in the laminated steel plate.
There was a problem in that drilling took more time than welding.

Therefore, Japanese Unexamined Patent Application Publication No. 48-48346, Utility Model Application Publication No. 50-
As described in Publication No. 6'713.4 and Japanese Unexamined Patent Publication No. 59-11-3988, auxiliary electrodes are provided on the front and back surfaces of the laminated steel plate to electrically short-circuit the upper steel plate and the lower steel plate. The laminated steel plate is attached to form an energizing circuit, the insulating layer between the electrodes is melted by energization, the insulating layer is removed, and then the laminated steel plate is welded to another steel plate.

In order to melt the insulating layer of a laminated steel plate, it is known to flow a melting current necessary to melt the insulating layer to melt the insulating layer, as described in Japanese Patent Application Laid-Open No. 49-37846.

[Problem that the invention attempts to solve]

However, in the conventional spot welding method, a small current is passed through the laminated steel plate to melt the insulating layer, and then a large current is passed between the laminated steel plate and the other steel plate to weld the laminated steel plate and the other steel plate. As a result, a large current flows through the laminated steel plates without completely removing the insulating layer in the areas to be welded, resulting in problems such as incomplete welding or cracks in the laminated steel plates.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a method for spot welding laminated steel plates that can improve welding quality.

[Means for solving problems]

In order to achieve the above object, the present invention provides a laminated steel plate having an insulating layer between the steel plates, with an upper layer steel plate and a lower layer steel plate on the front and back surfaces of the laminated steel plate, as shown in FIG. Attach a clamp member to electrically short-circuit the steel plates (Step 100), apply pressure to each steel plate by pressing electrodes to the front and back surfaces of the laminated steel plates to be welded (Step 1o2), and attach a small plate to melt the insulating layer between the two electrodes. Step 104) of applying a current, after the insulating layer has melted, a medium current is applied between the two electrodes to remove the insulating layer between the two electrodes from the current-carrying circuit and to create a nugget between the insulating layer and each adjacent steel plate. After a nugget is formed in the flowing step 106), a large current is passed between both electrodes to enlarge the nugget and weld both steel plates to other base metals (step 108).

[Effect]

Clamp members are attached to the front and back surfaces of the laminated steel plates, and electrodes are pressed against the front and back surfaces of the laminated steel plates to be welded to apply pressure to each steel plate, and a surface current is passed between the two electrodes to melt the insulating layer. After the insulating layer is melted, a medium current is passed between the electrodes to remove the insulating layer between the electrodes from the current-carrying circuit and to create a nugget between the insulating layer and each adjacent steel plate. After the nugget is formed, a large current is passed between the electrodes to enlarge the nugget and weld both steel plates to other base metals.

[Embodiments of the invention]

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

2 to 4 show the configuration of an embodiment to which the present invention is applied. In FIG. 2, a steel plate 1o is attached to the front and back surfaces of the laminated steel plate 16 as a pre-work to perform spot welding on a laminated steel plate 16 having a sandwich structure having an insulating layer 14 formed of resin between the steel plate 10 and the steel plate 12. A copper clamp member 18 is attached to electrically short-circuit the steel plate 12 and the laminated steel plate 16, and electrodes 20 and 22 are pressed against the front and back surfaces of the laminated steel plate 16 to be welded to apply pressure to the laminated steel plate 16. In between, a small current is passed to melt the insulating layer 14. That is, the electrode 20.
The insulating layer 14 between the electrodes 20 and 22 is melted by the pressure applied by the electrode 20 and the current flowing through the electrode 20, the steel plate 10, the clamp member 18, the steel plate 12, and the electrode 22. That is,
In this embodiment, first, by passing a small current through the laminated steel plate 16 for several cycles to melt the insulating layer 14,
This is to prevent cracks from forming in the laminated steel plate 16 during spot welding.

Next, while the laminated steel plate 16 is pressurized by the electrodes 20.22, the insulating layer 14 between the electrodes 20.22 is completely removed from the current-carrying circuit, and the insulating layer 14 is placed adjacent to the insulating layer 14. A medium current is passed between each steel plate 10, 12 such that a nugget 24 as shown in FIG. 3 is formed. This medium current is passed for a longer time than the energization time shown in FIG.

As a result, the portions of the steel plates 10 and 12 between the electrodes 20 and 22 are welded together.

Next, as shown in FIG. 4, between the electrodes 20° and 22,
Expand the nugget 24 and transfer the steel plate 10°12 to another base material 2.
A large current is applied to weld with 6. This energization time is 0
．． When spot welding a 9 mm laminated steel plate and a 0.8I 5PC28 steel plate, the time for flowing a large current is generally longer than the time for flowing a medium current. Note that the pressing force is kept constant.

In this way, in this embodiment, the laminated steel plate 16
A small current is applied to melt the insulating layer 14, and then a medium current is applied to the laminated steel plate 16 to completely remove the insulating layer 14 and form a nugget 24 between the steel plates 10° and 12°.
After this, a large current is applied to the laminated steel plate 16 to form the steel plate 10.
12 is welded to the base metal 26, it is possible to prevent cracks from forming in the laminated steel plate during spot welding and from not completely welding the laminated steel plate and other steel plates, thereby improving welding quality. can contribute to

〔Effect of the invention〕

As explained above, according to the present invention, a small current is applied to the laminated steel plate to melt the insulating layer, and after the insulating layer is melted, a medium current is applied to the laminated steel plate to remove the insulating layer between the electrodes, and the laminated steel plate is melted. Creates nuggets on the steel plate,
After the nugget is formed, a large current is passed between the electrodes to enlarge the nugget, thereby welding the laminated steel plate to other base metals, which has the excellent effect of contributing to improved welding quality.

[Brief explanation of drawings]

Figure 1 is a flowchart for explaining the present invention, Figure 2 is a flowchart for explaining the present invention;
The figure shows an example of the present invention, and is a diagram for explaining the action when removing an insulating layer. Figure 3 is a diagram for explaining the action when forming a nugget. Figure 4 is a diagram showing a laminated steel plate and other base materials. It is a figure for explaining the effect|action when welding and.

Claims (1)

[Claims] (1) Among laminated steel plates that have an insulating layer between the steel plates, clamp members that electrically short-circuit the upper and lower steel plates are attached to the front and back surfaces of the laminated steel plates, and the welding process of the laminated steel plates is performed. Pressure is applied to each steel plate by pressing electrodes on the front and back surfaces of the steel plate, and a small current is passed between the two electrodes to melt the insulating layer. After the insulating layer has melted, the insulating layer between the two electrodes is removed from the current-carrying circuit. A medium current is passed between both electrodes to form a nugget between each steel plate adjacent to the insulating layer, and after the nugget is formed, a large current is applied to enlarge the nugget and weld both steel plates to other base metals. A method for spot welding laminated steel plates, which is characterized by welding fluid between both electrodes.