JPS588955B2 - Seam welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for simultaneously welding appropriate nuggets between three or more metal plates, in which at least one of the overlapping plates has a thickness different from the others. This relates to a seam welding method in which seam welding is performed continuously in a direction.

The conventional seam welding method includes a welding current of 1 as shown by the single-phase alternating current waveform in Figure 1A of the attached drawings.
Continuous energization method in which energization is continuously applied, and energization time 2 of welding current 1 shown by the single-phase alternating current waveform in Figure B.
There is an intermittent energization method that alternately repeats energization at 3 and a pause at rest time 3.

Among these conventional seam welding energizing methods, Fig. 1A
The continuous energization method shown in FIG. 1B is used when welding thin metal plates at high speed, but the intermittent energization method shown in FIG. 1B is commonly used.

However, depending on the conventional intermittent energization method, for example,
In seam welding in which three or more overlapping metal plates of different thicknesses are welded as shown in FIGS. 2 and 3, the following disadvantages occur.

That is, when seam welding is performed by applying pressure and current using the rotating disk electrodes 4, 4', the welding conditions are adapted to the thin metal plate 5, and the pressurizing force and welding current by the rotating disk electrodes 4, 4' are reduced. In addition, if the current application time is to be shortened, in the combination of materials to be welded as shown in FIG. 2, there is a gap between the thin metal plate 5 and the thick metal plate 6 as shown in FIG. A continuous nugget 7 is formed in the direction of the weld line, but no nugget can be formed between the two thick metal plates 6 and 6l.

Furthermore, in a combination of materials to be welded having an auxiliary electrode plate 8 between the thick metal plates 6 and 6' as shown in FIG. 3, this also applies as shown in FIG. A continuous nugget 7' is formed between the thin metal plate 5 and the thick metal plate 6, but no nugget can be formed between the thick metal plates 6l and 61.

Conversely, thick metal plates 6 and 6' or 6' and 6
If the welding conditions are adapted to 1, the pressing force and welding current by the rotating disk electrodes 4, 4' are increased, and the energization time is lengthened, the same result can be achieved for the combination of materials to be welded as shown in Fig. 2. As shown in Figure B, a continuous nugget 9 is formed between the thick metal plates 6 and 6', but no nugget is formed between the thin metal plate 5 and the thick metal plate 6.

In addition, in the combination of materials to be welded as shown in FIG. 3, as shown in FIG.
Only a continuous nugget 9' is formed between the plates 5 and 6', and no nugget can be formed between the thin metal plate 5 and the thick metal plate 6.

Also, if welding conditions are set to intermediate conditions between a thin metal plate, a thick metal plate, and a thick metal plate, if the thickness ratio of the thin metal plate and the thick metal plate is small, Continuous nuggets 7, 9 or 7', 9' can be formed, however, the welding condition latitude in such a case is smaller than in the case where all the metal plates have the same thickness, and furthermore, This welding condition tolerance decreases as the plate thickness ratio increases, and when the plate thickness ratio exceeds a certain value, even if a large welding current that melts the surface is applied, continuous nuggets cannot be separated between each plate of the metal plate. It becomes impossible to form a

In this way, when seam welding three or more metal plates with different thicknesses using the conventional intermittent energization method, the welding condition latitude is small and the weldable plate thickness ratio is limited to a small range. .

The method of the present invention eliminates such conventional drawbacks, increases the welding condition tolerance in seam welding of three or more metal plates with different thicknesses, and increases the plate thickness ratio of weldable metal plates. The purpose is to obtain a welding method using such an energization method.

Hereinafter, the method of the present invention will be explained based on the accompanying drawings showing one embodiment thereof.

In FIG. 4, the intermittent welding current 11 has a current value that is large enough to meet the welding conditions for welding thin metal plates and that causes nugget nuclei to form between thick metal plates, and in the first half of the current flow time. The latter welding current 11' has a current value smaller than the earlier welding current 11' which is applied in the latter half of the welding time and which is suitable for the welding conditions for welding a thick metal plate. and an energization time 1 during which the intermittent welding current 11, especially the early and late welding currents 11' and 11' are applied, respectively.
2 consists of the time during which the early welding current 11' is applied, that is, the early current application time 12/, and the time during which the latter welding current 11 is applied, that is, the latter current application time 12'. The first current application time 12' is a current application time that is suitable for welding conditions for thick metal plates, and the first current application time 12' is a current application time that is suitable for welding conditions for thin metal plates.

The method of the present invention has the above configuration, and its operation will be explained next.

First, the initial welding current 11 has a current value adapted to the welding conditions between thin metal plates, for example, the welding conditions between the thin metal plate 5 and the thick metal plate 6 shown in FIGS. 2 and 3.
When ' is energized for the initial energization time 12', a continuous nugget 7 or 7' is formed between the thin metal plate 5 and the thick metal plate 6 in the direction of the welding line, and the gap between the thick plates, i.e., as shown in FIG. A small nugget is generated between the thick metal plates 6 and 6', or between 6' and 6' in FIG. 3, which becomes the nucleus for the growth of the nugget 9 or 9/.

Subsequently, the latter welding has a current value that is lower than the earlier welding current 11' and is suitable for the welding conditions between thick metal plates, for example between 6 and 6' in FIG. 2, or between 6' and 6' in FIG. A current 11' is applied during a later energization time 12' that is compatible with the welding conditions.

Due to the energization during the latter energization time 12'', the thick metal plates 6 and 6' that occurred during the earlier energization time 12' or
The small nugget between 6' and 6' grows and expands to become a large nugget 9 or 9'.

By repeating such operations, nuggets are formed continuously in the welding direction.

In this way, between the thin metal plates, i.e. metal plates 5 and 6 in FIGS. 2 and 3, and between the thick metal plates, i.e. metal plates 6 and 6' in FIG. while,
In addition, in FIG. 3, a nugget is formed between all the metal plates 6' and 6' during the intermittent energization time 12, and by repeating this process, a nugget is formed continuously in the welding line direction. Nuggets can be formed.

As described above, according to the present invention, in the welding process of stacked plates that requires both seam welding between thin metal plates and seam welding between thick metal plates, the magnitude of the early welding current and the latter welding current is controlled. Even if the thickness ratio between the thin metal plate and the thick metal plate is such that no nugget is formed between the desired plates when the size remains the same, the method of the present invention can provide a satisfactory continuous Nuggets can be formed between the desired plates.

As described above, according to the method of the present invention, it is possible to increase the welding condition latitude in seam welding three or more metal plates with different thicknesses, and also increase the thickness ratio between the weldable thin plate and thick plate. At the same time, continuous nuggets can be simultaneously formed between the respective metal plates more stably than in conventional methods.

[Brief explanation of the drawing]

Figure 1 is a welding current waveform diagram showing the conventional energization method in seam welding, where A is the continuous energization method, B is the intermittent energization method, and Figures 2 and 3 are the welding current waveform diagrams showing the conventional energization method in seam welding. Fig. 3 is an explanatory diagram of the nugget generation process based on the seam welding method, and Fig. 3 is an example in which an auxiliary electrode plate 8 is provided in the middle. FIG. 4 is a welding current waveform diagram of an energization method according to an embodiment of the method of the present invention. 1, 11... Welding current, 2, 12... Current application time, 3...
Pause time, 4, 4'... Rotating disk electrode, 5... Thin metal plate, 6, 6', 6'... Thick metal plate, 7, 7'... Nugget generated between thin metal plates, 9 , 9l... Nugget generated between thick metal plates, 11l... Early welding current according to welding conditions for thin metal plates, 11'... Late welding current depending on welding conditions for thick metal plates, 12'... Early energization time according to welding conditions for thin metal plates, 12'...Late energization time according to welding conditions for thick metal plates.

Claims (1)

[Claims] 1. Three or more metal plates, at least one of which has a different thickness from the others, are stacked, the stacked metal plates are sandwiched between a pair of electrodes, and the electrodes are placed between the metal plates. In a method of simultaneously seam welding the welded portion between the metal plates by passing a single-phase alternating current welding current with intermittent current-carrying periods between the electrodes while moving the electrodes relative to A seam welding method characterized in that at least two types of current are applied in succession. 2. The seam welding method according to claim 1, wherein at least two types of current are applied in order of magnitude of current value, with the current having the largest current value first.