Study Of Intelligent Control System In Spot Welding

With the extensive use of resistance spot welding and gradually maturing of intelligent control technology, intelligent control technology used resistance spot welding process and quality control are imperative under the situation. In this thesis, fuzzy logic control has been used in resistance spot welding. On the basis of fuzzy logic, an intelligent control system of resistance spot welding is designed and constant current of intelligent control in resistance spot welding process is realized.In this paper, many ways of resistance spot welding quality control are analyzed and compared for on general ground. A general scheme is presented, which is that fuzzy logic control is introduced to resistance spot welding process and quality control. Then the technical line, the feasibility and the rationality of this scheme are analyzed and demonstrated. The constant current of intelligent control system is designed and regarded 80K196KC single micro-computer as the core. In the course of research, simulation of fuzzy controller, important parameters of optimization and performance of improvement are achieved.The constant current of intelligent control system is composed of hardware and software. Hardware includes measuring circuit of current valid value, creating circuit of pulses about spot welding circle and constant current control, and assistant circuit such as keyboard, display and warning circuit. Software includes control main program, some interrupt programs, and functioning subprograms. Design procedure, theory of operation and program function of hardware and software are introduced in detail.Finally, the abnormal occurrence and creator of problem such as current measuring abnormal and turbulences in control process, and improving ways during the general debugging are analyzed deeply. Errors from current measuring and sequence lagging from constant current control are compensated in designing software, which can insure control accuracy and reliability of control system. During the course of testing on site, the server testing of control system is done on the condition of three different conditions such as electrodes short-circuit, stainless steel welding and low carbon steel welding. The result of testing on site manifests that the effect of spot welding constant current control is good. The largest absolute error between current valid value and current setting value is 270A, the largest relative error is 2.093%, and the average different value is 124A. The result of testing meets the request of design and use. Moreover, the error source and the error which may arise of control system are analyzed.The achievement that the thesis makes has certain theory and project practical value for realizing the intelligent control of spot-welding process and quality.