JPH0340666B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a welding current control method for spot welding equipment.

BACKGROUND TECHNOLOGY For example, as shown in Japanese Utility Model Application No. 59-10984, a first spot welding gun is attached to a predetermined welding position of a welding jig, etc., while a spot welding gun is attached to a position away from this first spot welding gun. A power supply terminal connected to the spot welding gun is provided, and this power supply terminal is held under pressure by another portable second spot welding gun to supply power to the first spot welding gun on the welding jig side. Devices for welding are known.

FIG. 4 is an explanatory diagram showing the outline of the process, and 1, 1, .
The spot welding guns 3, 3... are a plurality of power supply terminals installed at positions apart from the first spot welding guns 1, 1..., and these power supply terminals 3, 3...
... are respectively connected to the first spot welding guns 1, 1, . . . by power supply cables 4.

Then, due to the action of the pressurizing cylinder 2, the first
After the spot welding guns 1, 1, . By holding them together, the first spot welding guns 1, 1, . . . are energized to carry out spot welding. In this case, the second spot welding gun 5 is not only used for power supply, but also can weld parts that cannot be welded with the first spot welding guns 1, 1, . . . . In addition, 6 is a transformer,
7 is a timer.

Problems to be Solved by the Invention In the spot welding apparatus as described above, the conditions of the dot positions (material, plate thickness, overlap of the workpiece W, Since the second spot welding gun 5, which is common to all spots having the same number of spots, etc.), is used,
The welding current is controlled by the timer 6 according to preset conditions so that the welding current at each welding point position is equal. This means that since the portable second spot welding gun 5 does not have a welding current switching control function, the firing phase of the start signal to the timer 6 is fixed when energizing.

Therefore, in the conventional method, the material of the workpiece,
Since it is not possible to perform so-called heat control, which switches the welding current value (ignition phase) according to differences in plate thickness and number of stacked plates, it is necessary to specify multiple dot positions with different conditions such as material, plate thickness, number of stacked plates, etc. Since welding is performed under one welding condition, the welding conditions must be set on the timer side to match the welding point that is most disadvantageous among all welding points. As a result, for example, an excessive amount of heat is applied to the welding point location where welding is advantageous, and dust, burrs, etc.
Not only will weld defects such as pinholes occur, but this will also lead to early damage to the electrode tip.

The present invention is based on the energization method as shown in the above-mentioned Japanese Utility Model Publication No. 59-10984, and even when a portable second spot welding gun is used, it is possible to The purpose is to provide a method that allows the optimal welding current to be selected each time depending on the number of sheets and the like.

Means for Solving the Problems In the present invention, each power supply terminal is individually provided with a pressure sensor that detects that the power supply terminal is pressurized and clamped by a portable second spot welding gun. When welding with the first spot welding gun, the welding current value is selectively switched on the timer side to match the applicable dot position condition based on the detection output from the pressure sensor of the applicable power supply terminal. do.

The dot position conditions mentioned here refer to the material, plate thickness, number of stacked pieces, etc. of the workpiece to be welded.

Effect According to this method, the welding points handled by the plurality of first spot welding guns are determined in advance for each spot welding gun, and the optimal welding current value according to the welding point position conditions of each welding point is determined in advance. It is set. Therefore, when a corresponding power supply terminal is pressurized and clamped by a portable second spot welding gun during welding by any first spot welding gun, the power supply terminal that is pressurized and clamped is The welding point at which welding should be performed is specified by the detection output from the pressure sensor, and the ignition phase of the welding current is adjusted on the timer side so that the welding current value is optimal according to the welding point position conditions of that welding point. can be switched automatically.

Embodiment FIGS. 1 and 2 are diagrams showing a more specific embodiment of the present invention.

As shown in the figure, a plurality of first spot welding guns 11a to 11d are aggregated into four groups A, B, C, and D each with four first spot welding guns 11a to 11d, and each group A, B,
Welding will be performed using different dot position conditions for each of C and D (however, welding will be performed at the 1st and 4th points in each group).
(Only the first gun is shown). In other words,
For example, spot welding guns 11a to 1 of group A
1d is in charge of welding all dots with the same dot position conditions such as material, plate thickness, number of stacked sheets, etc. of the workpiece, and B
The group spot welding guns 11a to 11d are A
A group refers to welding of dots with different dot position conditions.

A power supply terminal 13 is individually connected to the first spot welding guns 11a to 11d of each group A, B, C, and D via a power supply cable 4, and a pressure sensor 8 is connected to each power supply terminal 13. are provided separately. More specifically, as shown in FIG.
4 and a pressure sensor 8 is sandwiched in a sandwich-like manner, and as will be described later, the power supply terminal 13 is connected to a portable second spot welding gun 15.
The pressure sensor 8 detects that the electrode 19 is pressurized and clamped, and the detection output is input to the timer 16 side.

As shown in FIG. 2, the timer 16 includes four starting switches (including key circuits) 9a, 9b, 9c, which are provided corresponding to each group A, B, C, and D and are selectively switched. 9d, and a phase switching control unit 1 that switches and controls the ignition phase of the welding current to create the corresponding welding conditions in response to a selection command from any one of the start switches 9a, 9b, 9c, and 9d.
Contains 0. In other words, the phase switching control section 10
has a four-phase control function according to the dot position conditions of each group A, B, C, and D. 12 is a pressurizing cylinder as a pressurizing means, and 18 is a sirisu type contactor.

In the spot welding apparatus configured as described above, for example, the power supply terminals 13 of the first spot welding guns 11a to 11d corresponding to groups A, B, C, and D are connected to the portable type second spot welding gun 15. Assuming that welding is carried out sequentially by applying electricity by clamping under pressure, the first
When performing welding with the spot welding guns 11a to 11d, in any case, the power is supplied by holding the corresponding power supply terminal 13 under pressure with a portable second spot welding gun 15 held by the operator. and welding is performed.

In this case, when the pressure sensor 8 detects that the power supply terminal 13 of the corresponding spot welding gun is pressurized and clamped by the second spot welding gun 15, the start switch 9a of the timer 16 is activated.
When the switch is turned ON, welding conditions that match the welding point position conditions of group A are selected. That is, by turning on the start switch 9a, the ignition phase of the welding current is controlled to match the welding point position conditions of group A, and as a result, an optimal welding current value is obtained.

In addition, the first spot welding gun 1 of group B
The same applies when welding according to steps 1a to 11d.
Suppose that the first spot welding gun 11a of group B
- 11d is more disadvantageous than the spot welding guns 11a to 11d of group A than the spot welding guns 11a to 11d, that is, the spot welding conditions of group B are such that the thickness of the workpiece is larger or there are more overlaps, Even if a larger amount of heat is required, the power supply terminal 13 of the corresponding spot welding gun in group B is connected to the second spot welding gun 15.
The pressure sensor 8 detects this when it is clamped under pressure. Then, in response to the detection output of the pressure sensor 8, the start switch 9b is turned on, and the ignition phase of the welding current is switched to match the welding conditions of the B group, resulting in a larger welding current than when welding the A group. Welding is performed using the welding current value.

As described above, according to the present invention, the pressure sensor 8 attached to each of the first spot welding guns 11a to 11b specifies the welding point position to be welded from now on, and the welding point position is determined according to the welding point position conditions. Since the welding current is switched by
Even if welding is performed in random order without being limited to B, C, and D, welding can always be performed under the optimal welding current.

Effects of the Invention As described above, according to the present invention, when the power supply terminal of the first spot welding gun provided for each welding point position is pressurized by the portable second spot welding gun, the power supply terminal By detecting it with the attached pressure sensor and switching the welding current to match the dot position conditions,
Portable type 2nd for multiple hitting positions
When performing welding by sequentially selectively applying current using spot welding guns, even if the order of welding is not necessarily determined, it is possible to identify which welding point position or the first spot welding gun was selected and automatically adjust the welding current. Since the welding current can be switched automatically, the optimum welding current that matches the welding point position conditions can always be obtained even when welding is carried out manually using a portable spot welding gun, and there is no need to over or under the welding current as with traditional methods. In addition to improving welding quality, it is possible to prevent damage to welding chips and extend their service life.

In addition, the desired purpose can be achieved simply by adding a pressure sensor to existing equipment. The structure of the spot welding device does not become complicated.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an embodiment of a device to which the method of the present invention is applied, Fig. 2 is a detailed view of the main part of Fig. 1, Fig. 3 is an enlarged view of the power supply terminal, and Fig. 4 is a conventional welding method. FIG. 2 is an explanatory diagram of the device. 1...Power supply cable, 8...Pressure sensor, 1
0...Phase switching control section, 11a, 11b, 11
c, 11d...first spot welding gun, 12...
...Pressure cylinder, 13...Power supply terminal, 15...Second spot welding gun, 16...Timer, W...
...The object to be welded.

Claims (1)

[Scope of Claims] 1. A first spot welding gun that is individually provided for each welding point position corresponding to a plurality of welding points and has a pressurizing means, and a spot welding gun that is installed at a position apart from the first spot welding gun. and a plurality of power supply terminals respectively connected to the plurality of first spot welding guns via power supply cables, and the workpiece to be welded is held under pressure by any one of the selected first spot welding guns. Thereafter, in a welding current control method for a spot welding device, in which the first spot welding gun is energized by pressing and holding the corresponding power supply terminal with a portable second spot welding gun, the power supply terminal is connected to the first spot welding gun. A pressure sensor that detects whether the spot welding gun is pressurized and clamped by the second spot welding gun is individually installed on each power supply terminal, and when welding with any first spot welding gun, the pressure sensor of the corresponding power supply terminal is 1. A welding current control method for a spot welding device, characterized in that, based on a detection output from a spot welding device, a timer side selectively switches a welding current value to match a corresponding dot position condition.