Based On The Dynamic Characteristics Of The Feed System Adaptive Speed Planning Method

Frequent changes in speed during CNC machining not only affect the machining efficiency of the machine tool,but also have a great impact on the mechanical transmission system of the machine tool,reducing the service life and machining accuracy of the machine tool.Forward-looking speed planning is to use different acceleration and deceleration methods to make the command speed smooth transition,while ensuring the processing accuracy while ensuring the processing efficiency.At present,the acceleration and deceleration parameters of CNC machine tools are obtained by experienced workers repeatedly trial and error when debugging the machine tool.There is no clear theoretical guidance and the basis for selecting the optimal parameters.In response to this problem,this paper proposes an adaptive speed forward control method based on the dynamic characteristics of the feed system.By analyzing the impact of the dynamic characteristics of the feed system and the acceleration and deceleration parameters on the system output,the acceleration and deceleration based on the dynamic characteristics of the feed system is established The method of parameter determination and the development of the speed-forward module based on the open CNC system.The main research contents of this article are as follows:Through theoretical analysis,a dynamic model of a flexible feed system based on a two-inertia system is established,the influence of mechanical transmission system parameters on the resonance of the mechanical transmission system is analyzed,and the three-loop control parameters are tuned in consideration of mechanical resonance.The model analyzes the influence of mechanical transmission system parameters on the dynamic characteristics of the feed system.For the same input signal,the simulation analysis of the influence of the dynamic characteristics of the feed system on the torsional amplitude of the two inertial systems,the relationship between the resonance frequency and the maximum torsional amplitude is analyzed,and the maximum torsional amplitude is increased with the resonance frequency.The law of rapid decrease at first and then slow decrease.Through the frequency analysis of the interpolation command,the frequency distribution of the command signal under different acceleration and deceleration parameters of linear acceleration and deceleration and S-curve acceleration and deceleration are studied respectively,and the acceleration and deceleration parameters under linear acceleration and deceleration and S-curve acceleration and deceleration are simulated and analyzed The law of influence on the torsional amplitude of the mechanical system is obtained,and the maximum torsional amplitude is linearly correlated with the increase of acceleration.The linear acceleration and deceleration and the S-curve acceleration and deceleration parameters are analyzed separately.Efficiency affects the law.By limiting the torsional amplitude of the mechanical system,comprehensively considering the mechanical resonance and processing efficiency,the matching relationship between the acceleration parameters and the dynamic characteristic parameters of the mechanical transmission system is established,which provides a theoretical basis for the subsequent adaptive speed forward planning method.Based on the matching relationship between the acceleration parameters,the dynamic characteristic parameters of the mechanical transmission system and the acceleration time,a forward-looking control module composed of forward-looking control and an interpolation algorithm based on the difference principle is established,and the secondary development is completed on the motion controller PMAC.Finally,the system identification of the experimental platform is carried out,and simulation verification experiments are carried out on the identification model.The experimental results are in line with expectations.