基于管坯径向挤压外壁凸台的成形极限研究

Research on forming limit of outer wall boss based on radial extrusion of tube blank

为探究管坯径向挤压外壁凸台的成形极限,利用Deform-3D有限元模拟分析软件研究了成形过程中管坯内径d_(0)、外径d_(1)、管坯壁厚t、凸台型腔高度h以及宽度w等关键参数对成形质量的影响规律。结果表明,成形的初始阶段易产生管坯内壁凹陷和折叠等缺陷;管坯所能成形无缺陷凸台轴向截面积(w×h)的最大值与d_(0)、d_(1)和t有关。定义S=(h/t)×(w/t)表征成形的安全性,成形安全性极限值由S_(d)表示,S_(d)值仅由d_(0)/d_(1)决定;当S>S_(d)时,成形初始阶段会发生管坯内壁凹陷、折叠,反之不会出现内壁凹陷、折叠。研究得到管坯径向挤压外壁凸台成形初始阶段的成形极限图,确定了成形参数选择的安全区域与危险区域。经物理实验验证,成形极限图安全可靠。

To explore the forming limit of outer wall boss in radial extrusion of tube blank,the effects of key parameters in forming process such as inner diameter d_(0),outer diameter d1,tube wall thickness t,boss cavity height h and width w on forming quality were studied by Deform-3 D finite element simulation analysis software.The results show that defects such as depressions and folds on the inner wall of tube blank are easy to occur in the initial forming stage;the maximum axial cross-sectional area(w×h)of the defect-free boss that can be formed by tube blank is related to d_(0),d_(1)and t.The definited S=(h/t)×(w/t)characterizes the forming safety,and S_(d),which is only determined by d_(0)/d_(1)represents the limit value of forming safety.If S>S_(d),the inner wall of the tube is recessed or folded in the initial forming stage;on the contrary,those defects do not occur.The forming limit diagram of the initial forming stage for the outer wall boss of the radial extrusion of tube blank was obtained,and the safe area and dangerous area for forming parameters are determined.It has been verified by physical experiments that the forming limit diagram is safe and reliable.