基于变结构刚度抑制精密孔镗削加工的颤振

Suppression of chatter for precision hole boring based on variable structural stiffness

精密孔镗削过程中出现的颤振现象会直接导致加工精度低和表面质量差等问题。本文针对镗削过程中最为常见的再生型颤振建立了动力学模型,研究了变结构刚度方法对切削颤振的抑制机理,并在此基础上提出了相应的控制策略。设计制作了一种基于磁流变液的智能镗杆,可以通过调节外加磁场强度的大小完成刚度和阻尼特性参数的无级变化,实现智能镗杆系统动态特性的在线调控。最后,在车床CA6140上搭建了磁流变智能镗杆的颤振抑制实验系统,实验结果表明,变结构刚度方法能够快速高效地抑制镗削过程中产生的颤振,并且使加工表面的粗糙度Ra从10μm降至1.5μm,大幅度提高了加工表面质量。

To suppress the chatter occured in precision hole boring process and to reduce the influence on the quality of workpiece,a dynamic model of regenerative chatter,one of the main type chatters in boring process, was established, and the suppression mechanism for the chatter based on a variable structural stiffness method was analyzed. Then, the suppression strategy of chatter was put forward. Furthermore,a magnetorheological （MR） intelligent boring bar was developed to achieve the stepless changes of stiffness and damping parameters by adjusting a magnetic field and implement the control for the dynamic characteristics of MR intelligent boring bar. Finally, the experimental setup of MR intelligent boring bar was built on the CA6140 type lathe. The experimental results show that the method can suppress the chatter efficiently and can improve the surface quality of workpieces significantly, whose roughness has decreased from 10μm to 1.5 μm.