Study On Intelligent Control System Of Resistance Spot Welding Quality Based On Double Processors

Resistance spot welding is a kind of important welding method which is widely used in automobile, aerospace and so on. With the continuous expansion of its application fields, the higher requirements of control system are put forward. However, the resistance spot welding is a complex process which is highly-nonlinear, multi-variable and strong coupling. The quality is affected by various factors and the traditional quality control methods using a single-parameter feedback have limitations and drawbacks to some extent. For this reason, the double processors control system is proposed in this paper. The 89C51 single chip is used as kernel of the system, and the real-time performance is increased. The multi-parameters fusion intelligent control can be realized through rational assignment of the duty of double processors.The hardware circuit and control system are designed. The clock circuit module, A/Dand D/A converter circuit module, keyboard and display circuit are analyzed in detail. The welding sequence, double processors serial communication, keyboard and display, A/D and D/A converter process, the digital PID algorithm are programmed. The electrode displacement system is designed, the grating sensor which has small size and high resolution is adopted to measure the displacement during spot welding. The current effective value is calculated by the method of peak value angel. The mathematic model is established based on RBF neural network, using the parameters of welding current, welding time, electrode pressure and board thickness as input of neural network system, and the nugget diameter as output of it, from which the optimized parameters of spot welding is realized. The orthogonal experiment is carried out on low carbon steel plate in different technological parameters for many tests, by which the optimal combination of technology parameters is abtained. The neural network model is also verified through experiments.The spot welding results show that the estimated error is less than eight percent, which expresses that the established model is precise, so the estimated result is reliable. The predicted precision can meet the actual production request. The research results have great values in theory and application for spot welding.