Development Of The Intelligent Control System For The Electro-Fusion Welding Machine

Polyethylene (PE) pipes are widely used in construction, industry, agriculture and many other fields because of their excellent characteristics such as long lifespan, corrosion resistance, ease of construction, etc. The quality of pipeline joint is the most critical factor which influence the service lifetime of the pipeline system, and electro-fusion (EF) welding is the most commonly used method for pipe connection in the pipeline construction. Nondestructive testing technology to detect the quality of PE pipe is not mature so far, so it’s very import to strictly implement the welding specification and decrease the influence of human factor so as to guarantee the quality of pipeline joint. In order to address the deficiencies of EF welding machine and improve the quality and efficiency of welding, automatic welding technology is researched and an intelligent control system of EF welding machine is designed.Firstly, the development of EF welding machine automatic welding technology is studied, combine the features of EF welding machine in the market and actual practice demand, the overall scheme of EF welding machine control system is identified. Master-slave structure is employed in the control system, in which the master is the industrial main board and the slave is the power output control board. The industrial main board connected with external devices to realize functions such as human interaction, data storage, information inquiry, etc. The power output control board connected with the power source and realized corresponding functions such as output sample and control.Secondly, according to the overall design scheme and functional requirements, the hardware implementation solution of the control system is identified and the hardware design is introduced in this paper. Noise and voltage ripple suppression method is studied, hardware circuit tests results show that the system can stably run for a long-time. Designed the software based on the hardware circuit and corresponding functions are realized.Thirdly, the implementation of thermostat welding mode is studied and the control strategy is determined. The mathematical model of EF welding pipe is identified through theoretical derivation and experiment. Based on the model, PID control, fuzzy control, fuzzy-PID control simulation experiments are conducted separately. The experimental results indicate that fuzzy-PID control has the best control effect.Finally, EF welding experiments are conducted based on the control system, constant voltage mode, constant current mode, constant temperature mode are tested separately. The experiments results indicate that the EF welding control system can guarantee the welding quality for the advantages of high control precision and good control effect.