Research On High Speed Turning Technology Of Complex Surface Based On RM-FTS

The implementation of national Ⅵ standard requires the piston to bear higher gas pressure.The traditional aluminum silicon alloy material has become more and more difficult to adapt to higher gas pressure because of its low compressive strength.Forged steel piston has made rapid development in recent years because of its excellent performance,especially in heavy-duty diesel internal combustion engine.Compared with the traditional aluminum alloy piston,the forged steel piston has higher hardness,strength and so on,but it also corresponds to higher cutting force requirements,which requires the tool holder to have stronger system support stiffness.The original fast tool servo(FTS)system can no longer meet the stiffness requirements.This thesis presents a new FTS system structure driven by small inertia rotating motor,and studies the new structure and its application in forged steel piston machining.The main research contents are as follows.Firstly,through the kinematic analysis of the profile of the special-shaped cylindrical section of the piston,the requirements of the FTS system for the key parameters such as reciprocating stroke,response frequency and acceleration are clarified.Compared with linear motor,rotating motor with the same volume can achieve greater driving force output.In this thesis,a new type of high rigidity fast tool servo system driven by small inertia rotating motor(RM-FTS)is constructed,a bilateral "face-to-face" horizontal opposed double guide rail structure is adopted to improve the support stiffness of the FTS system.Based on the principle of homogeneous transformation,the mathematical model of FTS system transmission structure error is established,and the error mapping model of guide rail and work slide is established.Analysis believes that compared with the traditional double guide rail structure,the error homogenization effect of "face-to-face" horizontal opposed double guide rail structure is increased by 5%in the main bearing direction and 4.4%in the feed direction.The static analysis and modal analysis of the "face-to-face" horizontal opposed double guide rail structure model are carried out through ANSYS software to optimize its structure,the error offset is reduced by 14.92%and the system stiffness is improved.The three loop control model of RM-FTS system is constructed,and the frequency response method is used to solve the transfer model function to realize the parameter identification of the control model.Based on Simulink,the response characteristics,robustness and tracking stability of RM-FTS system under different load inertia are compared and analyzed,and the reasonable value range of inertia ratio is determined;In order to improve the tracking accuracy of the transmission structure and shorten the response delay time,a feedforward controller is designed to improve the tracking accuracy of the system.The machining experiment of piston skirt verifies the effectiveness of the mechanical structure and control strategy of RM-FTS system.In order to solve the problems of piston profile customization and interpolation data fitting and generation,a set of human machine interface(HMI)system that can realize data visualization is developed in this thesis.Through each module,the design process of piston outer circle profile is simplified,which can greatly shorten the development cycle of piston,extract the piston radial data according to the angle and height interval given by the operator,and generate a data table that can characterize the radial reduction of piston outer circle,which can be used to guide the actual processing of piston outer circle.