Research On A New Principle Involving A Double-Side Displacement-Shift-Rotation Surface Lapping Method And The Surface Integrity

Currently,the lapping method of two-axis certain eccentricity is used in most surface lapping machine both at home and abroad.Its lapping principle may lead to heterogeneity in lapping trace and relative velocity along radium distribution on the workpiece surface,and the closer to the rotation center of workpieces,the worse the processing quality will be.To overcome this inherent defect,a deep research and analysis in the lapping principle and the trace of certain eccentricity lapping was done in the paper,through which the root of the problem was found,and a new principle involving a displacement-shift-rotation lapping method,was proposed based on the result.About the new principle,we did discussions and experiments in the theoretical analysis,motion simulation,experimental platform construction,position/force control and surface integrity.The details are listed as the following:1.A new principle,involving a displacement-shift-rotation lapping method,was proposed,based on the traditional principle involving the certain eccentricity surface lapping method and its lapping traces.In the new method,workpieces make displacement-shift-rotations and can get timely-varied and uniformly distributed lapping traces on the machined surface.Feasibility of the new principle was confirmed through kinematic analysis,and mathematical models of rotation and displacement shift involved in the new method were built,which supported the controllability of the new method implementation.2.A conception of lapping coefficient and its calculation method were proposed,and the calculation formulas of lapping coefficient and lapping force were derived.An orthogonal experiment of lapping coefficient was carried out on the experimental platform,and the formula of lapping force under the experimental condition was fitted.The mechanical model of displacement-shift-rotation was built,and quantitative relations between velocity of both rotation and displacement shift and the velocity of feed motion and rotary speed of lapping disk were derived.3.Based on the new lapping principle,a new structure involving upper and lower lapping mechanism and a peculiar isolation-disk were designed,and an experimental platform,of 5 axis NC machine tool of double-side displacement-shift-rotation surface lapping with solid abrasive,was constructed.Besides,a method and structure of ultrasonic vibration displacement-shift-rotation lapping was proposed,through which the principle of this method was analyzed.4.A control strategy of position/force hybrid control based on space division was proposed and related experiments were done by using it.The results showed a stable lapping pressure and a high positioning accuracy,which meant an improvement in the uniformity of the surface quality and machining accuracy through the displacement-shift-rotation lapping method.The machined surface roughness Ra reached nanometer and the dimensional accuracy reached submicron.5.A control strategy of position servo and torque limiting based on technology library was proposed and the hardware equipment requirements for position/force hybrid control were simplified,which reduced auxiliary processing time at the same time.The result showed that the machining accuracy requirement of lapping process could be satisfied with this control strategy,the machined surface roughness Ra reaching nanometer and the dimensional accuracy reaching micron.6.Based on the subject supported by 863 Project,a research on the surface integrity of machined surface was conducted.In the new principle,the influence law of surface roughness,fractal dimension,residual stress by lapping pressure and velocity were discussed,which provided experimental basis and reference to study the characteristics of the combined interface of the lapping part.