JP2501909Y2 - Spot welding quality measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a spot welding quality measuring device for measuring welding quality during spot welding work.

(Prior Art) Spot welding, in which an object to be welded is sandwiched between copper or copper alloy electrodes and a large current is passed for a short time while applying pressure to form a nugget on the contact surface for welding, is used in the assembly line of automobile bodies. I can't miss it. In spot welding, the current value, pressure and energization time are controlled by the controller,
When forming a large number of nuggets on the same object to be welded, it is necessary to weld under the same conditions.

However, the electrode forming the welding gun of spot welding is easily worn, and the shape of the electrode tip changes due to the wear.
Therefore, even if the current value, the pressure, and the energization time are controlled by the control device and kept constant, the welding state can be varied, which causes deterioration of spot welding quality.

Therefore, conventionally, a welding quality measuring device such as an inter-electrode voltage monitor is installed between the electrodes of the welding gun to control the welding quality. This is effective when the work is an iron plate, and recently In the rustproof steel plate that is often used in the body, the steel plate is chemically surface-treated,
Accurate quality measurement is not possible.

Therefore, in the spot welding operation of a rustproof steel plate, when a certain number of welding points are reached, the electrode is moved to an electrode polishing step, and after electrode polishing, spot welding is performed again in the production line.

(Problems to be solved by the invention) However, as described above, when a certain number of welding points is reached in spot welding work of an anticorrosive steel plate, it is necessary to transfer the electrode to an electrode polishing step and perform electrode polishing. The wear state is empirically determined.Therefore, polishing may be performed even if the wear is not progressing, or spot welding may be continued without reaching a certain number of welding points even if the wear is progressing above a certain level. However, there is a problem that the spot welding lacks reliability.

This invention was made in view of the above circumstances, and the purpose thereof is to test the wear state of the electrode during the work of spot welding, measure the welding quality by spot welding, and perform the quality measurement accurately. It is to provide a spot welding quality measuring device capable of performing the above.

[Structure of Device] (Means and Actions for Solving the Problem) In order to achieve the above-mentioned object, the present invention installs a welding quality measuring test piece and an electrode polishing part within a moving range of a welding gun by a welding robot. To do. Then, after the object to be welded is spot welded a predetermined number of times in the production line, the welding quality measuring test piece is test spot welded by the welding gun, and the electrode of the welding gun is measured by the welding quality measuring device during the trial spot welding. . Based on the measurement result by this welding quality measuring device, the welding gun is returned to the production line to continue spot welding of the workpiece, or the welding gun is moved to the electrode polishing section to polish the electrode and the welding is completed. The gun is returned to the production line to perform spot welding of the workpiece.

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

FIG. 1 shows a quality measuring system for spot welding, and 1 is a welding robot. The welding robot 1 includes a movable arm 3 that is rotatable and rotatable with respect to the robot body 2.
The movable arm 3 is provided with a welding gun 4 for spot welding. The welding gun 4 is provided with a pair of electrodes 5, 5 facing each other, and sandwiches the welded portion of the workpiece 7 installed on the production line 6 and applies a large current for a short time while applying pressure to perform spot welding. The object to be welded 7 is, for example, an automobile body part, and is formed of a rustproof steel plate. The welding robot 1 is controlled by a robot controller 8, and signals from the well-known welding quality measuring device 9, electrode tip diameter measuring device 10 and electrode polishing machine 11 are transmitted to the robot controller 8 via a process controller 12. Is entered.

Further, a welding quality measuring test piece 13 made of an iron plate is installed at a position apart from the production line 6 within the movement range of the welding gun 4. This test piece 13 faces the welding gun 4 when the welding gun 4 is swung by the welding robot 1 and positioned on the opposite side of the production line 6, and the test piece 13
On the other hand, when performing trial spot welding with the welding gun 4, the welding quality measuring device 9 is connected to the welding gun 4. Further, within the moving range of the welding gun 4, an electrode tip diameter measuring device 10 and the electrode polishing machine 11 as an electrode polishing unit are installed at positions apart from the production line 6. The electrode polishing machine 11 is for polishing the electrodes 5, 5 of the welding gun 4 and dressing them in a reusable state. The electrode tip diameter measuring device 10 measures the tip diameter of the electrodes 5, 5 after the polishing process. To do.

The operation of the spot welding quality measuring system configured as described above will be described with reference to FIGS. 1 and 2.

The welding robot 1 is controlled by the robot control device 8, and the welding gun 4 spot-welds the workpiece 7 on the production line 6. Spot welding started,
When the spot welding reaches a certain number of times, the spot welding is temporarily stopped by a command from the robot controller 8. Then, when the movable arm 3 turns and the welding gun 4 faces the test piece 13, trial spot welding is performed on the test piece 13 as shown in step 100. When performing trial spot welding, the quality is measured by the welding quality measuring device 9, and step 10
It is determined whether or not the measurement result shown in 1 is acceptable, and if YES, the welding gun 4 is returned to the production line 6 by the movable arm 3 and the welding work of the workpiece 6 is continued. When the result is NO, the movable arm 3 turns to move the welding gun 4 to the electrode polishing machine 11, and the electrode polishing shown in step 102 is performed. The electrode tip diameter is measured by the electrode tip diameter measuring device 10 for the electrodes 5 and 5 that have been polished, and it is determined in step 103 whether or not the electrode tip diameter is acceptable. If YES in step 103, the welding gun 4 is returned to the production line 6 by the movable arm 3 and the welding work of the workpiece 6 is continued. When NO, the movable arm 3 is rotated and the electrode polishing machine 11 again causes the electrodes 5,
By polishing 5 and repeating this routine,
It is possible to always carry out spot welding work of constant quality.

In the embodiment described above, the electrodes 5 of the welding gun 4,
Although the electrode 5 is automatically dressed by the electrode polishing machine 11, it may be manually dressed, and the electrode tip diameter measurement does not necessarily have to be provided, and only the welding quality measuring device 9 may be used.

[Effect of the Invention] As described above, according to the present invention, after the object to be welded is spot-welded a predetermined number of times in the production line, the test piece is test-spot-welded by the welding gun, and the welding gun is used during the test-spot welding. Of the electrode is measured with a welding quality measuring device, and the welding gun is returned to the production line based on the measurement result to continue spot welding of the workpiece, or the welding gun is moved to the electrode polishing section to polish the electrode. As a result, the quality of spot welding can be measured efficiently and accurately, and there is an effect that highly reliable spot welding can be performed.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a block diagram of a quality measuring system for spot welding, and FIG. 2 is a flow chart. 1 ... Welding robot 4 ... Welding gun, 5 ... Electrode, 6 ...
... Production line, 7 ... Workpiece, 8 ... Robot control device, 9 ... Welding quality measuring device, 11 ... Electrode polishing part, 13 ...
…Test pieces.

Claims (1)

(57) [Scope of utility model registration request] 1. A welding robot equipped with a welding gun and a control device for controlling the welding robot. The quality of spot welding is measured during spot welding of an object to be welded by the welding gun in a production line. In a quality measuring device, a welding quality measuring test piece and an electrode polishing part are installed within the range of movement of the welding gun by the welding robot, spot welding is performed on a workpiece for a predetermined number of times in the production line, and then the welding gun is used to perform the welding. A test piece for quality measurement is subjected to trial spot welding, the electrode of the welding gun is measured with a welding quality measuring device during this trial spot welding, and the welding gun is returned to the production line based on this measurement result to perform spot welding of the workpiece. Spot welding quality measurement, characterized by continuing or moving the welding gun to the electrode polishing section and polishing the electrode. Location.