大型锥形方管特种成形工艺

在研究大型锥形方管无模拉伸变形机理的基础上，建立了大型锥形方管无模拉伸速度控制模型，制定了大型锥形方管无模拉伸特种成形工艺以及确定主要工艺参数.用无模成形代替普通的大型锥形方管生产工艺中的全部成形工序，工艺及设备简单，无模拉伸的同时完成形变热处理，提高产品的综合性能.该方法特别适用于强度高、摩擦力大、塑性低的变断面管件.模拟实验结果表明，无模拉伸工艺能够拉伸出较理想的锥形方管，产品的尺寸精度及外观均较折弯焊接的钢管优越.实际尺寸与理论尺寸误差小于78%，具有实用价值.

Special Technique for Forming Big Inch Tapered Square Pipes

The special dieless drawing technique and the mathematical model of dieless drawing speed for big inch tapered square pipes were established. The key processing parameters were determined based on our systematically researching and analyzing on the deformation mechanism of dielss drawing for big inch tapered square pipes. The dieless drawing technique and equipments were simple and for the tapered square pipe dieless forming， one dieless production procedure can replace all the forming procedure in the general. It completed the deformation heat treatment simultaneously during the dieless drawing process， which enhanced the overall performance of the products. The method is suitable especially for the variable section pipes with high strength， high friction and low plasticity. The experimental study showed that ideal tapered square pipes can be drawn by the dieless drawing technique and the size precision and surface quality of products are super compared with the bend welded steel pipes. The relative errors of tapered square pipes between the model calculation results and the experiment results are less than 78%， which indicated that the dieless drawing technique is with great practical value.