The Process And Applications Of High Frequency Welding For The High-efficient And Energy-saving Copper Tubes Or Pipes With Inner Grooved Used In Air Conditionings And Refrigerators

It is one of the key technologies to improve the heat transfer performance of tube used for air conditioning and refrigeration without "Fluorin" . Ihere are many channels or grooves in the inner face of inner grooved tube or pipe, so the areas of heat exchange and the efficacy of flow, so the heat transfer coefficient is obviously improved. High-frequency(H. F.)-induction welding is the best process for produce the inner grooved tube or pipe, because the forms of the channels or grooves can be changed discretionarily in the inner face of the tube or pipe, further more it can be improved much more that the heat transfer performance of this heat exchange tube, and lower cost of production with the great efficiency ,so it is a importance primary process in the international for high efficiency inner grooved tube or pipe manufacture. For quality problem of the productions that produced by the product line of H. F. for inner grooved copper tube that was imported by a corporation in JiangSu province, the technologies of manufacture and the microstructure of the tube welding with poor quality for H. F. inner grooved copper tube or pipe have been widely investigated in this paper .The optimum technological parameter and characteristic parameter of the parent of material , clearance of the roll-forming mills, inside diameter of the inductor have been determined; and two bugs have been shown by the investigators of the bug of the tube welding and the causes of the problem of poor qualities, there are paste weld and uneven margins, brought on the fall of the electrical current density on the weld edge, and uneven margins of the weld "Vee" edge. The ways to production and correct quality maintenance were displayed by the investigators of he technologies of manufacture by the H. F. for inner grooved copper tube or pipe . The general microstructure characteristics of the welding and "bond line" of the HAZ of welding of the H. F. inner grooved copper tube or pipe been investigated also, it shows the both results: The hourglass heat affected zone and flow lines are symmetrical around the bond line in a normal HF weld area. The bond line is formed by superpose of "flakes of grain" with the squeezed of the weld rolls.