基于赫兹理论的弹性磨具磨抛 M300 钢表面参数模型研究

目的由于弹性磨具与曲面接触特征的多样性,导致弹性磨具呈非常量磨损,使磨具的磨抛工况变得复杂,磨抛参数对表面精度的影响没有得到理论上的阐释,通过实验研究磨削过程的磨削参数变化规律与加工表面残留峰移除量的理论关系。方法针对M300钢高耐磨性的特点,通过对球头弹性磨具(油石)的微观接触分析,根据赫兹理论接触应力分布特点,数学推导得出在平面情况下残留峰移除率与影响磨削精度的主要参数的函数关系。结果根据磨削参数变化规律,考虑进给速度的变化,得出任一点的残留峰置的变化量为接触半径减去球头在一定位置下通过的距离,并推导出移除率Q=dh/dt=CPmατnα的预估参数值。根据最小二乘法算得当m=-3,n=-2时,C=1.55×105,移除面积与磨抛参数成正相关。结论通过磨削实验确定移除率待定参数值,从理论上确定影响磨削质量的法向压力和切应力对残留峰移除高度的影响,为曲面磨削弹性预估补偿研究提供参考。同时应适当减小弹性模量,增大法相压力及球头磨具半径,使得进给量增大,减小磨损,提高磨削效率。

Study on the Parameter Model of Grinding and Polishing the M300 Steel Surface by Elastic Abrasive Tools Based on Hertz Theory

ABSTRACT:Objective To study the theoretical relationship between the variation of grinding parameter and the removed amount of residual peak in grinding and polishing process by experiment in the context that the diversity of characteristics in contact with bend surface results in the irregular wear abrasion of elastic tools and complicates abrasive machining status and there is no theoreti-cal interpretation on the effect of grinding parameters on polishing accuracy. Methods Specific to the feature of high abrasion resist-ance of M300 steel, the analysis of the micro-contact of elastic ball abrasive tool ( whetstone) was conducted. Based on the features of contact stress distribution described in the Hertz theory, the functional relationship was mathematically deduced between the re-sidual peak removal rate and the main parameters which influenced the grinding accuracy in the plane case. Results According to the variation pattern of grinding parameters, considering the changes of feed rate, the amount of site change of residual peak x at any point was that the contact radius subtracted the distance which ball head passed by at a certain position. And the estimated pa-rameter value Q=dh/dt=CPmατnα was derived. According to the least square method, when m=-3, n=-2, C=1. 55×105, the re-moved area of grinding and polishing parameters were positively correlated. Conclusion By the grinding experiment, the values of the unknown parameters were determined, and the effect of the pressure and shear stress that impacted the quality of grinding on re-sidual peak height was theoretically determined, providing a reference for elastic compensation by grinding the bend surface. Mean-while, it was suggested to appropriately reduce the elastic modulus, increase the abrasive wear pressure and the radius of the ball head, so as to increase the feed rate, reduce abrasion wear, and improve the grinding efficiency.