管坯壁厚不均匀缺陷对铜管游动芯头拉拔过程影响分析

摘要

针对铜管管坯表面存在壁厚不均匀缺陷,为分析壁厚不均匀对铜管游动芯头拉拔过程的影响,采用壁厚不均匀度作为壁厚不均匀评价指标,并利用有限元分析软件MARC,建立壁厚不均匀铜管游动芯头拉拔有限元模型,对铜管游动芯头拉拔过程进行数值模拟.结果表明:随着壁厚不均匀度的增加,拉拔力逐渐减小,且大致成线性递减趋势,并产生波动,波动幅值随着壁厚不均匀度的增加而增大;游动芯头轴向位移和芯头窜动量都随着壁厚不均匀度的增加而增大,但增加的幅值逐渐减小;等效应力在轴向和径向的梯度逐渐增大,容易造成铜管在拉拔过程产生拉裂现象.随着壁厚不均匀度的增加,等效应变在径向和轴向存在严重分布不均匀,应变梯度较大,容易使铜管发生扭曲变形.%Considering the fact that the copper tube has uneven wall thickness defect, by using finite element analysis software MARC, taking the uneven wall thickness uniformity as the evaluation index, the drawing finite element model of copper floating core head is established in order to analyze the impact of uneven wall thickness on the drawing process of copper floating core head. The drawing process of the copper floating core head is also numerically simulated. The results show that with the increase of the wall thickness, the drawing force linearly decreases;the fluctuation amplitude increases with the increase of wall thickness uniformity;axial displacement of the floating core head increases when wall thickness uniformity increases but the amplitude decreases gradually. Equivalent stress gradient force in axial and radial direction gradually increases, which is easy to cause pipe crack phenomenon in the process of drawing. With the increase of the wall thickness, the distribution of the equivalent strain in the radial direction and the axial direction is uneven, and the strain gradient is large, which will cause the distortion of the copper pipe.