Research On Sliding Mode Control Method For Constant Force Turning Process

In recent years,intelligent manufacturing has been deeply rooted in the people's mind.Intelligent,rapid and efficient processing methods have become the new pursuit of mechanical manufacturing in the new century.Traditional machining adopts constant feed speed.In order to prevent the machine tool and cutter from being damaged by too much cutting force,we can only choose a lower feed speed,which leads to a long machining time and low machining accuracy,and can not meet the requirements of the new era of machining.In constant cutting force machining,variable feed rate machining is used,which can be used for high-speed machining when the cutting depth is small.Constant force turning is of great significance to shorten the machining time and improve the machining efficiency.When the traditional control method is used to control the turning process with constant force,there is a big overshoot of the cutting force response curve whenever the cutting depth changes suddenly.This problem has a great influence on machining accuracy and speed.In order to solve this problem,a traditional linear sliding mode controller is designed to reduce the overshoot of the cutting force response curve when the cutting depth changes abruptly,and then a complementary sliding mode controller is designed to reduce the tracking error and output chattering of the system.On this basis,a fuzzy global complementary sliding mode control strategy is proposed to accelerate the approach speed and further weaken the turning process The control outputs chatter and enhances the robustness of the arrival phase.Firstly,this paper improves the model of the original turning system,using the exponential empirical formula of cutting force calculation to replace the original proportional formula,considering the influence of various factors on the size of cutting force,increasing its non-linearity,so that the model of the improved turning system is more close to the actual turning process.Then,based on the theory of sliding mode control,the traditional linearsliding mode controller of turning process is designed to reduce the overshoot of the cutting force response curve when the cutting depth changes abruptly.On the basis of the traditional linear sliding mode control method,the complementary sliding mode controller of turning process is designed by combining the integral sliding mode surface with the complementary sliding mode surface,which keeps the linear sliding mode surface The chattering is weakened while reducing the order characteristic.The simulation results show that the sliding mode control method can effectively solve the problem that the cutting force response curve overshoot is too large when the cutting depth suddenly changes,while the complementary sliding mode control method can effectively weaken the chattering of the traditional linear sliding mode control method.Finally,the complementary sliding mode control is combined with the global dynamic sliding mode surface,and the fuzzy control strategy is used to set the constant speed approach law switching gain in real time online.A fuzzy global complementary sliding mode control strategy for the turning process is proposed to make the system globally robust.Performance,and further weaken chatter while accelerating the system's response speed.The simulation comparison test results show that the fuzzy global complementary sliding mode control method of the machining process proposed in this paper has fast response speed,small overshoot,strong anti-interference ability,and has global robustness,and the control quantity output chatter is small.