凹模型线对挤压过程的数值模拟和试验研究

本文用数值拟和试验研究相结合的方法分析凹模型线对挤压过程变形状态的影响。模拟计算采用刚塑性有限元法，试验研究用坐标网格法和密栅云纹技术。文章对文献中提出的圆锥凹模、余弦曲线凹模、等应变率曲线凹模、双曲线凹模、椭圆曲线凹模和最短流线凹模，以及另外新设计的正弦曲线凹模，进行数值模拟，得到了各种型线模挤压时的速度场、应力场和应变场，以及由于变形热效应引起的试件和模具温升。并用光刻网格法和密栅云纹法进行试验校核。计算结果与实验结果相互吻合良好，研究结果表明七种曲线凹模中，以新设计的正弦曲线凹模最佳，余弦曲线凹模次之，这两种型线凹模的挤压力低，而且内部应变分布均匀。

NUMERICAL SIMULATION AND EXPERIMENTAL INVESTIGATION OF THE EFFECT OF DIE PROFILES ON THE FLOW DURING METAL EXTRUSION

Numerical simulation with rigid plastic finite element method and experimental investigation with grid method and Mori6 technique were used to study the effect of die profiles on the flow during metal extrusion. Velocity, strain rate, stress and temperature field in the workpieces extruded with conical die, cosine curved die, constant strain rate curved die, hyperbolic curved die, ellipitical curved die and Richmond curved die as well as newly designed sine curved die were calculated. Boundary conditions of F. E. M. were checked with Mori6 pattern. Results show that among the seven kinds of dies, the best one is the newly designed sine curved die and the next is the cosine curved die. These dies carry out lower extrusion loads and more homogeneous strain distributions.