Research On High Precision Micro Feed Servo Tool Post System For Convex And Variable Elliptical Piston

The piston is the core part of the internal combustion engine and the most difficult part of the internal combustion engine.Enhancing the comprehensive performance of the piston is the most effective way to improve the effective power of the internal combustion engine and reduce the emission,noise and fuel consumption.The middle convex and variable elliptical piston has become the most widely used piston in internal combustion engines because of its superior performance.This kind of piston surface is complicated and the machining precision is difficult to guarantee.The traditional machine tool is difficult to realize the machining of this type of special shaped piston surface.Therefore,the research on the precision molding technology of the special shape piston face is of great significance.The forming mechanism of the middle convex and variable elliptical piston turning is studied.The turning shape of the medium convex elliptical surface is decomposed into two independent forming motions:the motion of the elliptical path formed by the tool relative to the workpiece and the motion of the convex curve trajectory of the tool relative to the workpiece.The motion characteristics of tool feed relative to workpiece are studied.A new dual drive system is used as a servo tool holder to reduce the friction nonlinear effect of low speed and high frequency reciprocating motion,and the precise dynamic modeling of the servo tool holder is carried out by using the centralized parameter method and the S-GMS friction model.The relationship between the control volume and the displacement of the worktable is established to provide a basis for the design of the control system.On the basis of establishing an accurate dynamic model,using the stability performance and tracking performance of the extended state observer in the ADRC,and combining the advantages of the sliding mode control for the disturbance insensitive,an adaptive sliding mode control method based on the linear state observer(ASMC-LESO)is designed,and the control is compared by simulation.The method and the ADRC method can track the input signal and verify the tracking performance.The hardware in the loop simulation experiment of single driving mode and double driving mode is carried out by using workbench.The sliding mode controller based on linear extended state observer is used to debug the parameters of the control system and to simulate the cutting tool feed curve of elliptical piston section with ellipticity of 0.2mm.The tracking error in both the single drive mode and the dual drive mode is compared respectively.The experimental results are further verified the feasibility of the SMC-LESO control system,and the dual drive mode has better trajectory tracking performance compared with the single drive mode when the same conditions are verified.The research content of this topic provides a new method for the machining of the middle convex and variable Ellipse Piston,and designs a reliable controller for the new dual drive servo tool holder,which helps to improve the control precision of the tool feed movement.