Temperature Analysis On Penetration Brazing Of Dissimilar Metal Wires

Since the exothermic cable low-temperature radiation heating system is characterized by high efficiency,energy conservation,environmental protection,as well as comfort and safety,it is internationally recognized as an advanced heating system.The key technology of this system is the manufacture of wire core in the exothermic cable,which is connected by cable core made of copper supply leads(cold wire,diameter?0.4 ~ 1.13mm)and Ni base alloy heating coil(heated wire,diameter?0.3 ~ 0.85mm)paired connection,while the high quality,reliable connection determine the safety,life,quality of cold wire and hot wire.Therefore,the manufacturing method and equipment of the exothermic cable core has become the core technology of the global manufacturers in the exothermic cable industry.At present,the mainstream technology of exothermic cable core manufacturing is the brazing technology adopted by Nexans in France,Ensto in Finland and other world-famous manufacturer of heating cables.Therefore,on the basis of the analysis to the welding process technology of the heating cable core and equipment,the Key Laboratory of Special equipment and Manufacturing technology in Guizhou Province further explores the mechanism of butt welding of Cu/Ni base alloy wire to provide theoretical guidance for optimizing the welding processThe project,funded by NSFC(Natural Science Foundation of China)(51664006),focuses on the affecting factors and distribution regularities of welding heat,investigates the mechanism of the contact resistance to the temperature field in the welding process.The specific work is as follows:1.The paper conducts a thorough analysis of the formation mechanism of the wielding heat source in the Cu/Ni base alloy golden cable brazing,applies the microscopic contact behavior between the static copper electrode and nonmetal heating element through the method of fractal theory,and combined with the contact area,pressure,and micro-topography to deduce contact resistance model of the establishment of Cu/Ni base alloy golden cable brazing,and further verifies the validity of the model.2.The paper sets up an experimental test platform of Cu/Ni base alloy golden cable brazing with the function of temperature data collection,pressure test,measurement of contact resistance and others,so as to accomplish the investigation of affecting factors such as different pressures,different electrode structures,influence of different graphite carbon-rod on the contact resistance and temperature field in weld pool.Besides,the ablation test of ordinary graphite rod is carried out on the experimental platform,and the influence of the ablation temperature on the temperature field is further analyzed.3.The paper sets up the simulation model that is in accordance with the actual conditions of welding heat of weld pool,makes the contact resistance as the entity unit with specific resistance,and carries out the thermal electric coupling simulation analysis on Cu/Ni base alloy golden cable brazing through the Thermal Electric module of ANSYS Workbench.Finally,the paper makes a comprehensive analysis of the effect of contact form,contact resistance,voltage,welding wire and other main controlled parameters on the welding heat,and provide a theoretical foundation for the optimization of real-time control research about welding quality and the optimization of technological parameters of the spot wielding.