Design Of Automatic Electrofusion Welding Machine For Connecting Polyethylene Pipes

At present,most of the electrofusion welding machine are 39.5V constant voltage output.The external scanning coder is used to scan the tube type and can not meet the welding requirements of different types of PE tubes from different manufacturers.In order to improve the quality of welding from the source of welding process,standardize the welding process parameters,reduce the difficulty of operation,this paper designed a fully automatic welding machine system for PE pipe fittings,the relevant research is as follows:Through the analysis of the physical structure,material properties and heat transfer mode of the PE pipe fittings at the welding process,a 3D transient finite element heat transfer model of the fused joint was established and the temperature field simulation was carried out during the electrofusion welding process.The effectiveness of the model was verified by experiments.The simulation test is conducted to analyze the influence of welding process parameters on the temperature field and welding quality at the fused joints.Then the welding process parameters are optimized.In order to make the electrofusion welding machine segment output stable,energy efficient,small size and light weight,the main circuit to take PFC and inverter circuit structure,the forward stage of the Boost PFC input AC voltage filtering and rectification and active power factor correction,the backward stage shift full-bridge inverter circuit to achieve ZVS soft-switching and DC/DC high-frequency power conversion.The controller chooses DSP chip TMS320F28027 to realize PWM phase-shifting pulse generation and high-speed signal processing.The paper through the theoretical analysis,simulation modeling and experimental verification of the way to complete automatic welding machine for PE pipe hardware and control system design of the entire process,including the overall program analysis,the main circuit topology selection,component parameter calculation and selection,DC/DC circuit open loop simulation,output voltage transfer function fuzzy PID control simulation Make PFC and phase-shift full-bridge DC/DC circuit and test the pre-stage PFC module stable output DC voltage 390 V ± 5%,power factor of 0.96,posterior DC/DC output voltage adjustable 0~48V,rated current 50 A,efficiency of 92%,to meet the needs of small and medium PE pipe fittings.In the end,the main function of the mobile client of the fully automatic PE pipe welding machine is designed and realized based on the actual operation process of the welding.