Research On The Method Of Feed Speed Planning For High Speed NC Machining Of Shoe-Last

High speed machining technology has become the mainstream mould processing technology because of its high efficiency,high quality and low consumption,of which appropriate feed speed planning is necessary.In the process of high speed machining,the axes of machine tool often vibrate intensely around the surface with complex contour,reducing the smoothness of machining,and influencing the processing quality for the impact on the work piece surface.This dissertation proposes a method of feed speed plaxning considering the constraint of kinematics characteristics of the machine tool axes aiming at the problem of appropriate feed speed planning in the process of high speed machining.The core content of the study is establishing a mathematical model for feed speed planning based on the method of solving differential by finite difference,which is used to adjust feed speed and complete the overall planning by fairing of acceleration curve at the same time.The aim of the present work is to improve the feed speed as far as possible with the axes movement constraints in accord with the premise,so that we could improve the machining efficiency and the processing quality,and reduce the impact of the machine tool.The main work of the paper is summarized as follows:(1)Confirming constraint numerical values of kinematics characteristics on each axis of the machine tool.This part illustrates the kinematics transform way of Five-axis CNC Machine Tool and the transformation relations between work piece and the machine tool coordinate system.Then a method to calculate the processing of each axis kinematics characteristic using finite difference is proposed,and the kinematics characteristic constraint values of machine tool axes are obtained based on the theoretical calculation and experiment.(2)The feed speed planning in high speed machining.The mathematical model of feed speed planning is proposed and solved according to the constraints of kinematics characteristics of each axis.Then,the acceleration curve of the axis whose kinematics characteristics exceeded the constraints is smoothed,on which the feed speed is adjusted,so it can be sure that the kinematics characteristics of each axis are within constraints in the processing process.(3)Software implementation and simulation verification of feed speed planning algorithm.Visual Studio 2013 development platform is used to design and implement the speed planning processing software.The overall planning of NC program feeding speed is carried out before processing,and the processing simulation of the program is executed with Vericut8.05 which verified the feasibility of the algorithm and software.(4)Shoe-last processing experiment.The NC program planned by the feed speed planning software is actually processed on the five-axis NC machine tool for the shoe last,then the time of processing is compared with the unplanned one,and the processing effect of the last is compared to verify the effectiveness of the feed speed planning scheme.