Research On Reverse Adaptive Compensation Algorithm For Machinin Contour Error

For the rapidly developing manufacturing industry,there exists an urgent need to develop methodologies for processing higher precision products at a lower cost.The error compensation technique has the advantages of low cost,fast features to enhance the precision of the machine tool,which has been widely concerned.Traditional methods of error compensation are mainly implemented through the laser interference detection instrument to compensate the geometric error of CNC machine tool,however these kinds of methods cannot compensate the error of machine tools caused by machining process,and the use of interpolation error compensation are always constrained by strong restrictions of numeric control system.To solve this problem,some researchers proposed an adaptive compensation algorithm for equivalent truss structures,which adds the error to each vertex of the CAD model.However,the discrete model is chosen as the basis of this algorithm,so that the continuity of the model cannot be satisfied,and the workpiece surface is easily ruined.Based on this situation,a new contour error compensation algorithm of based on reverse NURBS constrained optimization function is proposed,in order to improve the machining accuracy of machine tool without increasing the cost,which has important significance of the theory and engineering applicationBased on the idea of NURBS optimization function compensation,the weight of NURBS in the basis function is considered as variable value.And the actual machining error is used as feedback to NUBRS function through the method of constrained optimization.At last combining the filter function with NURBS global interpolation algorithm,a new NURBS contour after compensation is calculated.Compared with traditional models,the proposed method can use less measuring points to obtain higher accuracy,which greatly reduces the computational cost of compensation algorithm,from shortened from 286.29 s to 20.65 s.In addition,this algorithm can achieve high precision compensation when dealing with local small amount under the condition of G2 continuity.According to the actual contour of the benchmark workpiece measured by the three coordinate measuring machine,the contour after off-line compensation is obtained by implementing the inverse reconstruction algorithm proposed in this paper.The correctness and effectiveness of the proposed algorithm are verified by the comparison between theoretical calculation and experimental results.After applying the NURBS constrained optimization based error compensation technology to the benchmark the average contour error machined is reduced by 52.15%,and surface profile error is reduced by 54.47%,and error standard deviation is decreased by 48.91%.