Resistance Spot Welding System

Abstract

A resistance spot welding system, which is provided with: a mechanism that calculates and stores the time change of the instantaneous heat value. The time change of the instantaneous heat value is based on the constant current control to energize and form a suitable nugget during trial welding. Calculated from the electrical characteristics between the electrodes during welding; based on the time change of the instantaneous heat value stored above and the input from the outside after the trial welding, the energization method is divided into multiple steps, and the values ​​of each step are A mechanism that stores the time change of the instantaneous heat value and the accumulated heat value as a target value; an adaptive control mechanism that starts welding based on the time change curve of the instantaneous heat value stored as a target value during main welding and adjusts during welding The welding current or voltage is used to generate instantaneous heat and accumulated heat. When the time variation of the instantaneous heat deviates from the target time variation curve in any step, the adaptive control mechanism adjusts the difference during the remaining power-on time of the step. Compensate so that it is consistent with the target accumulated heat value for this step. It effectively copes with the wear of the electrode front end and the existence of external interference, and obtains a good nugget.

Description

technical field [0001] The present invention relates to a resistance spot welding system in which energization is carried out in two or more stages, and in particular to a resistance spot welding system capable of forming a suitable nugget by applying adaptive control welding in each step. Background technique [0002] In joining overlapping steel plates, resistance spot welding, which is a type of overlap resistance welding, is generally used. [0003] This welding method is a method of sandwiching two or more overlapping steel plates, applying pressure from above and below with a pair of electrodes, and passing a high-current welding current between the upper and lower electrodes in a short period of time to join. This method utilizes resistance heating generated by the flow of high-current welding current to obtain spot-shaped welded parts. This point-shaped welded part is called a nugget, and is a portion where the two steel plates melt and solidify at the contact porti...

AI Technical Summary

Problems solved by technology

However, it takes a lot of time and cost to derive the welding current change mode corresponding to a large number of welding conditions and workpiece conditions through experiments.

[0007] In addition, in actual construction, there are deviations in the development state of electrode wear, so it cannot be said that the predetermined welding current change mode is always appropriate

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