厚壁管件有芯棒开式冷挤压理论建模  

Study on the theoretical model of cold open-die extrusion with mandrel for the thick-walled tube

作　　者：张双杰[1,2] 李强[1,2] 李占华[2] 李军[2] 

机构地区：[1]燕山大学机械学院,秦皇岛066004 [2]河北科技大学材料学院,石家庄050018

出　　处：《塑性工程学报》2010年第6期67-71,共5页Journal of Plasticity Engineering

基　　金：河北省自然科学基金项目(E2004000296)

摘　　要：分析了厚壁管件有芯棒开式冷挤压成形特点及影响成形的参数,将此工艺分为外缩径内径不变、内扩径外径不变、外缩径内扩径3种形式,视前两种变形形式为外缩径内扩径变形的特殊形式。引入流函数,建立包含3种变形形式的统一连续速度场;根据速度场与应变速率场之间关系,确定了应变速率场;利用上限原理,得到了挤压功率、挤压力的理论模型。通过编程计算,得到了不同工况下的力-行程曲线,并与实验结果进行了对比,误差小于8%,满足工程需要。此模型可计算不同工况下的挤压力,用于厚壁管件有芯棒开式冷挤压成形工艺的制定及设备选择。The forming features and forming parameters of open-die extrusion with mandrel for the thick walled tube were analyzed.The process was divided into three forms：necking external diameter with invariant bore,expanding bore with invariant external diameter,and necking external diameter with expanding bore,while the first two forms were regarded as the special forms of necking external diameter and expanding bore.By the method of stream function,the uniform continuous velocity field containing three forms was established.The strain rate field was obtained according to the relation of the velocity field and the strain rate field.The theoretical model of extrusion power and force was obtained by the upper bounding theory.The relation curves of force versus displacement were provided by programming and calculating.Compared with the experimental results,the error is smaller than 8%,so that the model could be used to calculate the extrusion force under different conditions,to design the forming process of the open-die extrusion with mandrel for the thick-walled tube and to choose device.

关 键 词：有芯棒开式冷挤压 流函数 上限法 挤压力 

分 类 号：TG371[金属学及工艺—金属压力加工]