Simulation And Experimental Study On Adaptive Self-compensation Of Grinding Wheel-profile In Precision Freeform Grinding

The high-performance freeform surfaces are urgently needed in industries like home appliances,automobiles,shipbuilding and aviation.The freeform grinding by diamond grinding wheel can machine high-precision and smooth surface.However,the self-sharpening of abrasive grain for micro-cutting causes the rapid wears of wheel which leads to the uncontrollability of freeform form error.Generally,multi error compensations with repeatedly measurements are applied by numerically control of tool-path,but they are of complexity and inefficiency.Thus,a precision freeform grinding method with adaptive self-compensation of curved wheel-profile error is proposed.The mutual wear between curved wheel-profile and surface of workpiece enables the direct compensation of wheel-profile error in freeform grinding,reducing the freeform form error.The characteristic is to realize efficient precision grinding of freeform surfaces without high-precision form-truing of wheel-profile and subsequent compensations.In the research,according to the wheel wear principle of micro grain self-sharpening,the adaptive form-truing ability of grinding wheel is caused by the wheel wear.Firstly,the model of wheel wear rate between the wheel and the workpiece parameterized by the grinding parameters was constructed by the experiments.The adaptive self-compensation of wheel-profile error reaches optimum by control the optimum material removal after the wheel wear becomes stable.Then,the freeform grinding processing model of the freeform form error related to the wheel-profile error was constructed to simulate and analyze the relationship between the wheel-profile error and the freeform form error.The simulation result shows that the freeform form error decreases with increasing the wheel torus curvature and decreasing the freeform surface curvature.It greatly increases with freeform surface curvature for smaller wheel torus curvature.Finally,the freeform wheel-profile with adaptive self-truing ability was designed based on the characteristic of freeform workpiece;the model of adaptive self-compensation of wheel-profile error was constructed to analyze the feasible area of adaptive self-compensation with different grinding parameters.Analysis shows that the wheel compensative rate increases with increasing the cutting depth and the feeding speed,thus the surface accuracy improves.As the main factor,for example,the cutting depth increasing from 10 ?m to 30 ?m can enhance the wheel compensative rate by 53%.The freeform grinding experiments of mold steel by diamond grinding wheel was performed to verify the model of adaptive self-compensation of wheel-profile error aim to enhance the accuracy of freeform surface.The experimental results shows that he wheel compensative rates were 20.1% and 28.8% with cutting depth of 15?m and 30 ?m,basically in accordance with the simulation after modification of wheel wear rate.The wheel compensative rate was 8.0% when the cutting depth was 45 ?m.Therefore,the cutting depth must be controlled within the size of diamond grain in order to realize the effective adaptive self-compensation of wheel-profile error.Besides,in different removal volume of materials with the same grinding parameters,the surface accuracy improved by 17.2% when that of adaptively self-compensated wheel-profile improved by 27.8%.Therefore,the simulation model of adaptively self-compensative freeform grinding is feasible.