含缺陷钢丝多道次拉拔模拟及工艺参数优化

利用有限元软件ABAQUS建立了含缺陷热轧盘条多道次拉拔的分析模型， 研究了道次压缩率、模具顶角和裂纹长度对拉丝安全性的影响，以减少断丝率为目标探讨 道次压缩率和模具顶角的最佳配合方式. 研究结果表明：模具顶角相同时，COD值和$J$积分 值均随着裂纹尺寸的增加而增大；裂纹长度一定时，最佳入线直径随着模具顶角的增加而增 大；最佳模具顶角应在4°- 8°之间. 利用有限元方法和断裂力学理论模拟含缺陷的热轧盘条经过多道次拉丝成型的过程，建立了钢丝经过多道次拉拔模具发生拉拔变形的分析模型，用模拟方法重点研究了道次压缩率、模具顶角以及裂纹长度对拉丝安全性的影响，以减少断丝率为目标探讨道次压缩率和模具顶角的最佳配合方式；研究结果表明：模具顶角相同时，随着裂纹尺寸的增加，J积分值随之增大；裂纹长度一定时，随着模具顶角的增加，入线直径的条件最佳值也在增大；最佳模具顶角的范围应在4°－8°之间。在拉拔前应对线材进行无损探伤从而控制裂纹长度，提高线材使用率和成品质量。研究结果对进一步优化拉丝工艺参数和改进成品PC钢绞线质量提供了有价值的理论指导。

MODELING OF WIRE WITH FLAW IN MULTI-DRAWING AND OPTIMIZATION OF DRAWING TECHNIQUE

Numerical model of the wire with defect in the process of multi-drawing is built based on finite element method and fracture mechanics, and the effects of parameters (draft reduction, die angle and cracking) on the wire drawing are analyzed. It is concluded that the effective method to reduce the rate of broken rods is: choose the best parameters in multi-drawing process about the draft reduction and die angle; control the length of crack by using nondestructive examination to improve the quality of the finished product. The results show that values of $J$-integral and COD increase with the increasing length of crack in the same die angle; the best condition diameter increases with the increasing die angle in the same length of crack; the best die angle is in the range of 4$^\circ \sim 8^\circ$. The above findings can be used to improve wire drawing technique and the quality of wire.