TC4钛合金纵扭超声磨削力热耦合模型及其试验研究

Thermo-mechanics Coupling Model and Experimental Research of Longitudinal Torsional Ultrasonic Grinding of TC4 Titanium Alloys

为探究TC4钛合金纵扭超声磨削过程中的力热耦合机理,基于TC4钛合金纵扭超声磨削的磨削力模型、工件表面平均温度模型、质量热容计算表达式建立了其力热耦合模型,并对力热耦合作用下TC4钛合金纵扭超声单颗磨粒去除过程进行有限元仿真,分析磨削力、磨削温度的相互影响特性。理论与仿真研究发现,磨削区剧烈的温升会降低钛合金抵抗塑性变形的能力,抑制磨削力的增长速率。最后通过TC4钛合金纵扭超声磨削试验进行验证,结果表明,纵扭超声的引入能明显降低磨削力和磨削温度,磨削力和磨削温度的降低幅度分别达到19.39%和12.41%;磨削温度随着磨削深度、砂轮转速和工件进给速度的增大而升高,且随着磨削温度的升高磨削力增长趋势变缓;磨削力和磨削热的减小使工件表面塑性变形和犁沟两侧的塑性隆起高度减小;与普通CBN磨削相比,纵扭超声的引入对表面粗糙度的降低幅度可达到31.21%,在一定范围内增大超声振幅能显著提高加工表面的质量。

In order to explore the thermo-mechanics coupling mechanism in the longitudinal torsional ultrasonic grinding of TC4 titanium alloys,the thermo-mechanics coupling models were established based on the TC4 titanium alloy longitudinal torsional ultrasonic grinding force models,workpiece surface average temperature models,specific heat capacity calculation expressions.The finite element simulation of the TC4 titanium alloy longitudinal torsional ultrasonic single abrasive particle removal processes under the coupling of force and heat was carried out to analyze the interaction characteristics of the grinding forces and the grinding temperature.Theoretical and simulation studies show that the severe temperature rises in the grinding zones may reduce the ability of the titanium alloy to resist plastic deformations and to inhibit the growth rate of the grinding forces.Finally,it was verified by the longitudinal torsion ultrasonic grinding tests of TC4 titanium alloys.The results show that the introduction to ultrasonic vibration may significantly reduce the grinding forces and grinding temperature,and the reduction of grinding forces and grinding temperature reach 19.39%and 12.41%respectively.Grinding temperature increases with the increases of grinding depth,grinding wheel speeds and workpiece feed speeds.And with the increases of grinding temperature,the growth trend of grinding forces slows down.The decreases of grinding forces and grinding heats reduce the plastic deformations of the workpiece surfaces and the height of the plastic bulge on both sides of the furrow.Compared with ordinary CBN grinding,the introduction to longitudinal torsional ultrasonic may reduce the surface roughness by 31.21%.Increasing the ultrasonic amplitude within a certain range may significantly improve the grinding quality of the workpiece surfaces.