Influence of Welding Parameters and Environment Temperature on the Thermal Field of Electric Fusion Welding for PE Pipes
Electrofusion welding is a common method for connecting polyethylene(PE)gas pipes.Using SYSWELD soft-ware,a 1/4 axisymmetric finite element model of PE100 circular pipe electrofusion welding was established,considering the resistive heat generated by the heating wire as a volumetric heat source and simulating the heat exchange during the welding process through air convection and cooling surface dissipation.The melting temperature and decomposition temperature of PE100 material were obtained through DSC+TG combined test to obtain characteristic temperature data.The experimentally measured melting onset and peak temperatures of PE100 material were 118℃and 138℃,respectively,while the decompo-sition onset temperature was 272℃,and the decomposition temperature calibrated at 5%mass loss was 350℃.The pre-dicted value of the melting zone width was in good agreement with the measured value,with an error of less than 5%,verify-ing the effectiveness and accuracy of the adopted calculation method.The simulation results show that the welding voltage has a significant effect on the width of the melting zone,and a larger welding voltage generates sufficient heat input,thus ex-panding the width of the melting zone.However,excessive heat input will lead to overheating and decomposition of the plas-tic,forming pores,reducing the effective connection area,and may affect the mechanical properties of the joint.The ambient temperature significantly affects the formation process and final width of the melting zone by changing the initial tempera-ture and convection heat dissipation intensity of the welding structure.In actual production,it is necessary to optimize and adjust the preset parameters of the electrofusion sleeve according to specific environmental factors to ensure the quality of electrofusion welding.
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