Research On Electric Control System On Broaching Machine For Bush

Based on the technological gaps of error compensation technology on dynamicerror compensation in broaching machine industry, a new tactics of errorcompensation with Bayesian network PID (BNPID) is provided. An electric controlsystem of broaching machine for bush is proposed with this tactics. And then someexperiments have been done on this electric control system. Experimental resultsshow that broaching machine for bush with this electric control system have a higherprocessing precision than traditional broaching machines for bush. For this closedloop control system of broaching machine for bush, this paper introduces itsmechanical system and electro-hydraulic actuator power system, and completes thehardware design at the first. Secondly, a mathematical model for describing themachining tolerance which synthesizes both geometric and thermal tolerance isdeveloped with the mechanical system and volumetric positioning error of broachingmachine. Thirdly, BNPID controller is designed on the base of Bayesian network andthe previous mathematical model. Finally, some relevant software have been designedand some relevant experiments have been done.In chapter1, this paper introduces the background significance of errorcompensation of broaching machine, and elaborates the domestic and foreign researchpresent situation of related key techniques.In chapter2, some specific information of broaching machine for bush isintroduced, including closed loop control system, performance indicators, mechanicalsystem. And the hardware design of the electric control system is the key to thischapter which including high and low electric distribution (380v,220v), PLC moduleselection and components selection.In chapter3, many coordinate systems are established with the traditionalhomogeneous coordinate transformation theory and the mechanical system ofbroaching machine. Firstly, the basal coordinate system is established on the base ofthe broaching machine, and two child coordinate systems are established on thehorizontal and vertical motion axes. Secondly, geometrical transform matrixesbetween base, bed, main slide carriage, tool of the broaching machine are establishedand then the geometrical transform matrixes of the kinematic chain between the tooland the base is established on the base of the previous matrixes. The geometrical transform matrixes of the kinematic chain between the work-piece and the base isestablished in the same way. Finally, a mathematical model for describing themachining tolerance which synthesizes both geometric and thermal tolerance of thebroaching machine for bush is developed on the base of the two kinematic chain. Themathematical model of valve-controlled asymmetrical cylinder servo system is alsointroduced to build the mathematic relation between spool displacement and cylinderrod displacement in this chapter.In chapter4, a new tactics with BNPID is provided which can compensate bothgeometric error and thermal error. And thermal error is calculated with Bayesiannetwork on the base of PID theory and the mathematical model in chapter3. BNPIDcontrol strategy is a combination of PID theory, multi-error (geometric error andthermal error) mathematical model and Bayesian network. In this control strategy,thermal error is divided into3sections, and each section corresponds to8thermo-contact, then each section can be calculated with Bayesian network. BNPIDcontrol strategy owns some traits such as simple and effective, inherited from PIDtheory.In chapter5, the software of electric control system of broaching machine forbush is designed and some relevant experiments are done. The design of softwareincludes the design of PLC program of SIEMENS CPU315and the design of themonitor program with IPC-Industry PC. The experiments studied the control effect ofBNPID control strategy on broaching machine for bush.In chapter6, analysis and summarize of the content of this paper has been done,and make a outlook about the research direction of electric control system onbroaching machine for bush in future.