复杂曲面碳化钨密封零件精密磨削实验研究

A Study on Complex Surfaces of WC Hermetic Parts in Precision Grinding Process

碳化钨为典型的碳化物陶瓷材料,具有广泛的应用前景。其具有高硬度、高脆性及很高的耐磨性,所以难以采用传统的车削、铣削等工艺进行加工。在碳化钨工件上加工出复杂的曲面结构,并保证工件的面形精度及表面粗糙度则更加困难。为获得高表面质量的复杂曲面碳化钨密封工件,采用杯形金刚石砂轮单点磨削的方法实现碳化钨材料加工;设计压电陶瓷驱动柔性铰链微进给机构精确控制砂轮切深方向运动,从而实现复杂曲面加工的成形运动;探索最优工艺参数获得高面形精度和低表面粗糙度。分析了碳化钨磨削加工材料去除机理,以此指导柔性铰链精密进给机构设计,并规划杯形砂轮改善面形精度及表面粗糙度的磨削方法。实验结果表明:采用青铜基及树脂基杯形砂轮以45°倾角单点磨削碳化钨样件,其表面粗糙度值Ra由初始的500nm减小到15nm,面形精度RV值达到0.25μm。该装置可以在普通机床上磨削出高质量的碳化钨工件。

WC material is a typical of carbide ceramic material,which will be used wildly in the future.It has high rigidity,high brittleness and wearable quality,so it is difficult to machining by traditional turning or milling.If we want to machine complex surfaces in WC parts,it is more difficult to guarantee the form accuracy and the surface roughness.In order to obtain WC hermetic parts with ultra-precision form accuracy,we introduce the process method of reducing surface roughness by cup wheel of one-point grinding,meanwhile,we design the flexure hinge machine controlled by piezoelectric actuator to improve the movement precision of cup wheel and the form accuracy,and it is validated by experiments.Based on the wiping off mechanism of material in grinding process,we design the flexure hinge machine,and introduce the method of grinding with cup wheel to improve the form accuracy and the surface roughness.Experimental results indicated that the surface roughness Ra was reduced from 500nm to 10nm and the PV form accuracy reached 0.25μm when one-point grinding WC sample with bronze and resin grinding wheel at angle 45°.This equipment can effectively machining high quality of WC sample in common machine tools.