双金属复合管直角法兰双辊夹持旋压起皱分析

Analysis on Wrinkling in Double-Roller Clamping Spinning of Right-Angle Flange of Bimetal Composite Tube

为了将双辊夹持旋压成形技术应用于双金属复合管直角法兰成形,对Q235普通钢/304不锈钢双金属复合管管端的直角法兰双辊夹持旋压成形机理进行了研究。采用有限元分析软件建立了内层为304不锈钢、外层为Q235普通钢的双金属复合管的双辊夹持旋压成形有限元模型,通过有限元仿真模拟,分析了双辊夹持旋压成形过程易产生的起皱缺陷形式及其影响因素。研究结果表明,旋辊进给率和坯料的径厚比是起皱的主要影响因素:旋辊进给率越大则所需的成形转矩越大,在一定范围内工件的成形质量也越好,但旋辊进给率过大会出现不同程度的起皱现象;坯料径厚比越大,所需要的成形转矩就越小,而成形过程中旋辊接触部位存在切向压应力,使得在一定径厚比条件下可成形的法兰宽度存在极限值,大于极限值则会发生起皱现象。对起皱情况下的成形力进行了分析,发现可以利用旋压力曲线的突然波动来确定起皱发生的时刻。

To apply the double-roller clamping spinning(DRCS)process to forming right-angle flange of bimetal composite tube end,the forming mechanism of DRCS process for right-angle flange of ordinary Q235 steel/304 stainless steel bimetal composite tube is investigated,and a finite element model of DRCS for the right-angle flange of bimetal composite tube end is constructed.The inner layer of the bimetal composite tube is 304 stainless steel,and the outer layer is ordinary Q235 steel.Finite element simulation is conducted to analyze both the wrinkling form and its influence factors in the DRCS process of right-angle flange of the ordinary Q235 steel/304 stainless steel bimetal composite tube.The results show that the roller feed rate and the diameter-to-thickness ratio are the key factors influencing wrinkling in DRCS process.When the roller feed rate rises,the forming moment increases,and better forming quality of flange can be achieved within a certain range of roller feed rate.If the roller feed rate is too high,wrinkling occurs to different degrees.When the diameter-to-thickness ratio increases,the forming moment decreases.The tangential compressive stress exists in the roller contact area during the forming process,so the formed flange width has a limit value for a certain diameter-to-thickness ratio.If the flange width is greater than the limit value,the wrinkling occurs.The analysis of the forming forces in the wrinkling case shows that sudden fluctuation of the forming force can indicate the moment of wrinkling occurrence.