断面分流比对双孔分流模挤压方管焊合过程及焊合质量的影响

Influence of area ratio of portholes on welding process and quality during the extrusion of square tube by a porthole die

分流模挤压时各断面间分流比的合理匹配直接关系到挤压力的大小、金属焊合过程的流动均匀性、焊缝位置及焊合质量。采用有限元法计算研究了断面分流比对双孔分流模挤压方管焊合过程和焊合质量的影响。研究结果表明：当断面分流比为0.46-0.52时,金属在焊合室内流动均衡,焊缝保持在模芯中心附近,能够挤出表面平直的方管制品。断面分流比的变化对型材出口温度基本没有影响,其温度始终保持在546-549℃;随着断面分流比的增加,焊合静水压力逐渐减小,并由363 MPa减为314 MPa,使得焊合质量降低,因此,在保证能够挤出表面平直的方管的同时,应尽量减小断面分流比。

During the extrusion of hollow profile by a porthole die,area ratio of portholes is directly related to extrusion load,metal flowing uniformity in metal welding process,position of welding line as well as welding quality.Using FEM simulation and extrusion practice,the influence of area ratio of portholes on welding process and quality of square tube extruded by a porthole die was discussed.The results show that,as the area ratio is 0.46-0.52,the metal flowing is equilibria,and the welding line is more close to the center of the mandrel,so the square tube with flat surface can be extruded.The changing of area ratio of portholes has no significant effect on the final temperature of die orifice which remains within 546-549 ℃.With the increasing of area ratio of portholes,the hydrostatic stress of welding decreases from 363 MPa to 314 MPa,which leads to worse welding quality.Therefore,the area ratio of portholes should be small as soon as possible under the prerequisite condition of extruding square tube with flat surface.