Modeling And Realization For Cutting Process Of SiC Monocrystal Based On Optimal Control

SiC is not only the best material for producing high frequency,high temperature,high power electron device,but also the substrate material of GaN blue light emitting diode.It is a very important semiconductor material.Diamond wire saw cutting technology has been widely applied in the process of cutting hard brittle material because of its its narrow kerf width,environment friendly and slice high quality.Through experiment and theoretical analysis of the process parameters of cutting,found that the most significant process parameters impact of cutting force is the feed speed and wire speed,however,the feed speed and cutting speed directly determines the efficiency of the cutting process.To improve the cutting efficiency of the process,in this paper,the optimal control mathematics model of the minimum machining time of the feed system and the roller system of the rotary point cutting machine of the WXD-170-type reciprocating diamond wire is constructed.According to the influence factor of cutting force in the process of SiC single crystal cutting,the constraint conditions of cutting process are obtained,and using the minimum value principle solved the optimal control quantity and the optimal solution.The control variables and the state variables are simulated by Matlab system simulation software,the results show that:(1)The size of the control variable determines the stability of the system,normal force on the the workpiece is control vector of feed system and input torque of motor is control vector of roller system.Due to the use of optimum control,the force on the system tends to be stable,which established a good condition for machining excellent surface quality of the workpiece.(2)The state variable describes the change of the processing parameters of different time systems,feed rate is state variable of feed system and the angular velocity of the roller is state variable of roller system.Along with the processing progress,the processing environment has changed,making the system adjust to the state variable,and the system run in the optimal state.