SU941090A1 - Seam and spot welding quality control method - Google Patents

Description

The invention relates to the field of resistance welding and can be used to control the quality of joints in the process of welding thin-sheet materials.

Methods are known for quality control of spot and seam welding, based on measuring the amount of movement of a moving electrode in the process of thermal expansion of a metal as it flows through the welding current 1, 2.

A disadvantage of the known methods is the low accuracy of welding quality control. In addition, the implementation of known methods requires a complex construction of a measuring sysgheme.

Closest to the invention is a method of quality control of spot and seam welding, based on determining the magnitude of the acceleration acceleration of the moving electrode during the welding process and comparing the obtained value with a given value corresponding to the quality welding 3.

The disadvantage of this method is the low accuracy of the measurement of the acceleration of the moving electrode during welding of parts with a thickness of less than 0.1 mm. When welding parts with a thickness of less than 0.1 mm, the volume of the melt zone in the joint is relatively small and, therefore, small

level of the monitored signal proportional to the acceleration. This leads to the inevitable occurrence of significant errors in measuring the monitored parameter, reducing the objectivity of the control.

The aim of the invention is to improve the accuracy of control of welded joints from thin-sheet materials.

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The goal is achieved by the fact that in the method of quality control of spot and seam welding, based on determining the magnitude of the acceleration of the moving electrode during the welding process and comparing the obtained value with a given, corresponding to quality welding, the acceleration of the moving electrode is determined in the direction perpendicular to the welding direction. current in the basement

20 electrode.

The drawing shows a functional diagram of the method.

When the flow of welding current ICB through parts 1, clamped between the movable

25 2 and the stationary 3 electrodes of the machine, a molten core is formed in the weld zone. The movable electrode and the movable arm rigidly connected to it 4 along with the rise move in the direction 30 perpendicular to the direction of the welding current with acceleration a. At the output of the accelerometer 5, mounted on the console 4, an electrical signal f / ih is generated, which is proportional to the magnitude of the effective acceleration. The generated signal, U,., Is compared with the on-signal. The magnitude of signal mismatch serves as a determining parameter when assessing the quality of a welded joint.

With a decrease in the thickness of the parts, the displacement of the moving electrode with the welding process in the direction perpendicular to the direction of the welding current becomes greater than the displacement during its rise due to the forces of the dilatometric effect. A similar relationship is observed when measuring the acceleration of the movement of the electrode. When the thickness of the welded sheets is 0.1 mm, the acceleration of the moving electrode in the direction perpendicular to the welding current is 30% higher than the acceleration of its rise, with the thickness of the sheets 0.08 mm - 35-40%. The method confirms that there is a close connection between the acceleration of the movement of the moving electrode in the direction perpendicular to the welding current, with the dimensions of the connection. When welding materials with a thickness of 0.1 mm or less, it is advisable to use this parameter as a controlled one, since it considerably exceeds the acceleration of lifting and, therefore, is less sensitive to the influence of interference or the influence of external disturbing factors on the welding process on it. Usually, the most significant measurement errors are associated with the action of electrodynamic masses in the welding circuit. Under actual welding conditions, the measured signal is the sum of the accelerations of the movement of the electrode under the action of the thermal expansion of the metal and the electrodynamic forces caused by the flow of electric current in the welding circuit. The magnitude of the electrodynamic component of the acceleration depends not on the dimensions of the weld point, but only on the magnitude of the welding current, therefore it is parasitic. When registering the acceleration of the moving electrode in the direction perpendicular to the welding current, and accelerating its rise to the electrodynamic component, there are respectively 12-18 and 25-30% of the amplitude of the signal from the accelerometer.

Consequently, but the proposed procedure, the accuracy of control is increased not only by increasing the signal power, but also by reducing the level of the electrodynamic component of the acceleration.

The application of the method will improve the accuracy of quality control of welding parts from materials with a thickness of less than 0.1 mm by at least 30%.

Claims (3)

1.Orlov B. D. Control of spot and roller electric welding. M., “Mashchino0 building, 1973, p. 219-224. 2. USSR author's certificate number 228164, cl. In 23 K P / S, 1967. 3. Mironov L. G., Afanasyev L. K., 5 Zaitsev V. A. Quality control of compounds directly in the process of spot welding. “Welding production, No. 2, 1979, p. 28-30 (prototype). USb, x