JPS6251710B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spot welding method suitable for spot welding aluminum alloy or zinc plates that require high quality.

When spot welding aluminum alloys, a large current is used, so that the copper alloy at the tip of the electrode and the aluminum alloy that is the object to be welded become alloyed, causing a pick-up at the tip of the electrode. Once this pick-up begins to adhere, it increases at an accelerating rate, causing deformation of the electrode and poor cooling of the electrode, resulting in a stacking phenomenon in which the electrode and the object to be welded are welded together. In addition, irregularities in the shape of the indentation (roundness, shape, depth of indentation, etc.) on the workpiece and variations in the nugget diameter due to changes in current density occur. Therefore, dressing work must be performed to remove the pick-up on the electrode tip and shape the electrode tip every approximately 20 spots during spot welding.

Conventionally, this dressing operation is carried out by sandwiching a lever 3 wrapped with emery paper 5 between an upper electrode 1 and a lower electrode 2, gripping grips 4 attached to both sides and rotating it in the direction of the arrow, as shown in FIGS. 1 and 2. The pick-up at the tips of both electrodes 1 and 2 is removed by moving the electrodes 1 and 2, but it is very time-consuming because it is done manually, and it takes about the same amount of time as spot welding. This makes the workability very poor. Therefore, in order to rationalize the spot welding work, it is first necessary to automate and rationalize the electrode dressing work.

An object of the present invention is to automate and streamline spot welding work by automating the electrode dressing work, which occupies a large proportion of the work time, when performing spot welding on, for example, aluminum alloy vehicles. That is.

In order to achieve the above object, the present invention inserts an electrode plate between the spot electrode and the workpiece in spot welding, moves the electrode plate periodically after spot welding, and cleans the pick-up generated on the electrode plate. Further, the deformation of the electrode plate at the time of dotting is corrected using a correction roller, and this operation is continuously performed. As a result, there is no need to stop the spot welding operation due to the conventional electrode dressing operation, and the spot welding operation can be performed continuously.

Hereinafter, the present invention will be explained in detail with reference to an embodiment shown in FIGS. 3 to 5. Reference numerals 1 and 2 denote an upper electrode and a lower electrode held by upper and lower holders 13 and 13, respectively, which are forcibly cooled by cooling water flowing out through a water cooling pipe (not shown) provided at the center. 9 is a cylinder ram provided on the upper arm 7, and the cylinder rod 1 is provided with a holder 13.
0 is attached so that it can move up and down. Note that the lower holder 13 is attached to the lower arm 8. 11
12 is the current carrying plate of the upper electrode 1, 12 is the current carrying plate of the lower electrode 2, and 14 is the upper electrode 1, the lower electrode 2, and the workpiece 2.
It is an endless electrode plate inserted between 1 and 22 and used in circulation, and the material used is, for example, pure copper or chrome copper with a thickness of 1 to 2 mm. Reference numeral 15 denotes a cleaning device for cleaning the circulating electrode plate 14, which uses a wire wheel, for example, and is driven by a motor 16. 17 is a correction roller for the electrode plate 14;
8 is a feed roller, and 19 is a feed motor that circulates and feeds the electrode plate 14, and is controlled so as to be driven at times other than when hitting a point. The cleaning device 15, motor 16, straightening roller 17, feed roller 18 and feed motor 19 are attached to the holder 13.

When performing spot welding, the cylinder ram 9 is operated to lower the upper electrode 1 and the electrode plate 14 is
Through this, the objects to be welded 21 and 22 are pressurized and energized by the upper electrode 1 and the lower electrode 2. After spot welding, the electrode plate 14 is automatically rotated in the direction of the arrow 20 by a feed motor 19 and a feed roller 18, and dirt caused by pick-up of the electrode plate 14 during spot welding is cleaned by a cleaning device 15. The electrode plate 14 is always in contact with the objects to be welded 21, 22, the upper electrode 1, and the lower electrode 2 in a clean state. Note that the deformation of the electrode plate 14 used in spot welding is corrected by a correction roller 17 during the spot welding process.
used repeatedly.

In this way, spot welding can be performed through the electrode plate 14 which is always clean, so there is no need for special electrode dressing work, and spot welding work can be performed efficiently without downtime. Effective for spot welding of alloys or galvanized iron plates that require high quality.
It should be noted that the electrode plate 14 may be replaced with one having approximately the same size as the spot electrode instead of the endless one, but in this case there is a difficulty in handling the electrode plate.

Feed motor 1 that circulates and moves the electrode plate 14
Reference numeral 9 is a device that is driven at times other than when spot welding is performed, that is, when the electrode is moved up and down or when the object to be welded is moved, but the drive may be performed by manual switch operation after confirming the spot welding operation. Energizing upper and lower electrodes 1 and 2 and feeding motor 1
It is also possible to provide a control device that alternately energizes 9 and automatically energizes them. Note that it is desirable that the electrode plate 14 be moved for each point;
In some cases, it is also possible to move by an arbitrary number of dots, such as every few dots.

Since the present invention is as described above, there is no need to interrupt welding to carry out electrode dressing work, which was a conventional bottleneck in spot welding, and continuous spot welding is possible. This has the effect of automating welding work.

[Brief explanation of the drawing]

1 and 2 are a front view and a plan view showing the conventional dressing method, FIG. 3 is a side view of a spot welding machine for implementing the present invention, and FIGS. 4 and 5 are one example of the present invention. FIG. 3 is a front view and a side view of an upper electrode showing an example. 1... Upper electrode, 2... Lower electrode, 13... Holder, 14... Electrode plate, 15... Cleaning device, 1
7... Correction roller, 18... Feeding roller, 1
9... Feeding motor, 21, 22... Work to be welded.

Claims (1)

[Claims] 1. Perform spot welding by inserting an endless electrode plate that circulates between the spot electrode and the workpiece, move the electrode plate at times other than when welding points, clean the electrode plate after welding points, and then weld. A spot welding method characterized by correcting deformation of an electrode plate that occurs at the time of welding.