Research On A Machining Toolpath Corner Smoothing Method For Hybrid Robot

With the increasing demand for large and complex components and machining requirements in the aerospace field,industrial robots with high rigidity,large load capacity,and high precision are used more and more widely.Therefore,this paper takes a new type of five-axis hybrid robot as the object,to improve its machining performance,a method for corner smoothing of five-axis machining toolpath including arc position segment is studied.Firstly,the G3 continuous corner smoothing model of the tool position and the tool orientation under the limit of the smoothing error is established in the operation space.Secondly,the analysis and synchronization of the tool orientation and the tool position path parameters,to ensure the tool orientation path is C3 continuous.Furthermore,considering the driving performance of the hybrid robot and the geometric constraints of the machining toolpath,combined with the S-shaped acceleration and deceleration strategy,the research on feedrate planning and parameter curve interpolation is carried out.Finally,milling experiments are carried out to verify the effectiveness and applicability of the method proposed in this paper.Firstly,aiming at the tool position with arc segments,a G3 continuous corner smoothing model is established.Taking the 5th-degree B-spline curve as the smoothing curve,and considering the G3 continuity condition of the straight line and arc path primitives at the transition point,a method of analytically constructing the spline control points is proposed,which solves the problem of the smoothing error limit.The corner smoothing problems of three types of position paths: straight line-line segment,straight line-arc segment,and circular arc-arc segment,and a simulation study was carried out.The results show that the proposed method has strong error control ability and universality.Secondly,to realize the G3 continuous corner smoothing of the tool orientation path,taking the 5th degree B-spline curve as the smoothing curve,and considering the G3 continuity condition of the tool orientation path at the transition point,a method of analytically constructing the spline control points is proposed.On this basis,a corner smoothing model of tool orientation path is established under the limitation of the smoothing error.The analytical synchronization problem of path parameters in different position path splicing modes is studied,and the C3 continuity of the movement of the tool orientation at the span is realized.To verify the effectiveness of the proposed tool orientation path smoothing method,a simulation analysis is carried out.Furthermore,for the NC machining process of the hybrid robot,based on the above C3 continuous five-axis machining toolpath,the driving performance of the hybrid robot and the feedrate planning under the geometric constraints of the machining toolpath are carried out.To generate the continuous machining trajectory of C3 required for machining,a parameter interpolation study centered on the prediction-correction(PCI)strategy is carried out.The simulation results show that the proposed feedrate planning and parameter interpolation method has good performance.Finally,the TriMule-600 robot experimental platform developed by Tianjin University is used to carry out the machining experiment of the specimen.The validity and applicability of the method for corner smoothing of the machining toolpath with arc segments in the hybrid robot proposed in this paper are verified.