A novel force control method was proposed based on the Magnetorheological torque-servo (MRT) to control the polishing force to maintain a polishing pressure constant in precise NC polishing of aspheric parts. The mechanism, model and affecting factors of the method were investigated,and a corresponding polishing system was developed. Firstly, the mechanism of the polishing force control method based on the MRT was presented. Then, the principle of constant pressure polishing was analyzed by using Preston equation, and the model of polishing pressure was established according to Hertz theory. Finally, the control model of polishing force was deduced to realize the constant pressure polishing, and the affecting factors of model were discussed. Experimental results indicate that the surface roughness of the part improves from initial value 1.6 μm to 0. 067 μm and 0. 028 μm respectively, and the unevenness of surface roughness is 94.4％ and 11.4％, respectively, after polishing with the constant force and constant pressure and the polishing time in 90 min, which means the polishing quality and effciency have been improved greatly. It is concluded that the method can control the polishing force and polishing pressure independently, actively, and in real ime and can improve the surface quality of parts remarkably.%提出了一种基于磁流变力矩伺服装置(MRT)的研抛力控制方法来控制非球面数控研抛系统中的研抛力以实现恒压力研抛.研究了该方法的原理、模型、影响因素并研发了相应的实验研究系统.阐述了基于磁流变力矩伺服装置的研抛力控制原理;应用Preston方程分析了恒压力控制的重要性并基于Hertz理论建立了研抛压力模型,进而建立了研抛力控制模型,探讨了影响研抛力控制的主要因素;最后,规划了系统的研抛压力并进行了实验研究.实验结果表明,在研抛用时均为90 min的情况下,恒力研抛得到的非球面表面粗糙度为0.067 μm,表面粗糙度不均匀度为94.4%,而恒压力研抛得到的表面粗糙度为0.028μm,表面粗糙度不均匀度为11.4%,研抛质量和效率显著提高.该方法能够独立、主动、实时地控制研抛过程中的研抛力和研抛压力,实现非球面超精密、高效、低成本数控研抛.
展开▼
