A Winding Path Pre-smoothing Method For The Fouraxis CNC Lathe Winder

In the process of fiber winding,ensuring the smoothness of the movement of key components of the CNC winding machine is an important parameter that affects the winding quality,the stability of the winding equipment and the winding efficiency.The method of winding smooth control from the perspectives of interpolation,speed planning,and servo feedback control may face problems such as the large amount of calculation,low real-time performance,and reduced winding efficiency of the smoothing method,and it will bring high equipment manufacturing,maintenance and processing costs.In view of the above problems,this paper refers to the axis which has a great influence on the operation stability of the winding machine as the critical axis.The winding process of the four-axis lathe fiber winding machine is analyzed for calculating the slippage coefficient of the fiber on the core.Based on the slippage coefficient,the smoothing method of the winding trajectory and critical axes' speed is proposed.Then the points whose curvature is over the threshold,adjacent line segments are not uneven,and the chord points are used to select the feature points of the winding trajectory.Based on the fiber slip constraint,this paper uses the Bezier spline to spline the feature points,and then calculates the fitting error of the non-feature points.And refit the feature points if there are points which can't satisfy the fitting conditions.Finally,we get a smoother winding trajectory.Due to the existence of the rotary axis in the multi-axis machine tool,there is a nonlinear relationship between the machine system and the workpiece system in coordinate conversion.However,the smoothness of the winding trajectory cannot guarantee the smooth movement of the critical axis,so this paper uses wavelet transform to smooth the speed of the critical axis.Based on the smoothing synthetic trajectory,the position of the non-critical axis is calculated to adjust the deviation the winding trajectory caused by the smoothing of the critical axis.Finally,the fiber constraint is satisfied and the winding trajectory and the critical axis speed are relatively smoother.The fiber winding slip coefficient calculation software is developed then,which can calculate the fiber slip coefficient corresponding to each feature point according to the existing machine tool parameters and the geometric parameters of the cylindrical core mold,and identify the dangerous points with slip tendency.The numerical control system is used to simulate the processing of the instruction codes before and after the trajectory smoothing and the corresponding interpolation data is collected.By comparing and analyzing the experimental results,the winding trajectory and critical axis during the winding process are smoother than before.