Experimental Study On Wedm Of Workpiece With Variable Thickness In Water Mist Medium

WEDM is widely used in mechanical manufacturing field,with the extensive development of reciprocating walking wire WEDM,The workpiece with a single thickness gradually expands in the direction of complex workpiece with variable thickness,such as the seat hole,the ladder hole,the wedge table.As the change of workpiece thickness,surface quality and cutting speed will generate larger changes,and workpiece surface quality is inconsistent.In order to improve the machining quality and cutting efficiency of workpieces with variable thickness and meet the requirements of surface consistency,it is necessary to study the cutting characteristics of workpieces with variable thickness and find the cutting method suitable for workpieces with variable thickness.Through the experimental study of variable thickness,the surface consistency and cutting efficiency of workpiece are the best when different parameters are used to cut the surface of workpiece with different thickness,and the surface quality and cutting efficiency of workpiece with variable thickness are greatly improved,which is of great significance to the machining of workpiece with variable thickness.First of all,through mechanical processing characteristics experimental study the variable thickness of the workpiece in the emulsion,the steam spray,ultrasonic spray,we can get variable thickness workpiece change rule under all kinds of medium,such as the cutting speed of workpiece,the workpiece surface roughness,straightness,surface actual cutting depth,material removal rate,discharge,the changing rule of the discharge gap.Then,doing variable thickness workpiece experiment in steam spray WEDM,through the first variable thickness workpiece’s parameter optimization experiment in emulsion we get the optimal parameters doing prepare for a second finish in the mist.Through variable thickness workpiece’s second single factor experiment in water spray medium,we know the pulse parameters and the offset of variable thickness workpiece surface getting influence on roughness andcutting speed.Second,designing BBD central composite experiment based on response surface analysis,we can establish model about variable thickness workpiece surface roughness and cutting speed,through the variance analysis we get the significance and primary and secondary order of various influencing factors with their interactions,weighted comprehensive evaluation model is established by analytic hierarchy process(AHP),roughness and cutting speed’s weights were 40% and 60%respectively.The efficiency coefficient method was used for homogenization treatment,and then the Matlab multi-objective optimization iteration was carried out by particle swarm optimization(PSO).The optimum cutting parameters of workpiece with variable thickness’ s secondary incision in steam fog are optimized.The method of machining workpiece with different thickness with different parameters is proposed,and the control test is designed.The experimental results show that the variable parameter cutting can greatly improve the surface roughness consistency of workpiece with variable thickness and improve the cutting efficiency.Finally,a thickness identification model based on generalized grey theory is established.we do some theoretical analysis to find the main factors which influence thickness identification.we can get taguchi experiment design by minitab software,and doing the key factors’ s analysis for affecte factors of kerf width,kerf width model is set up which is based on grey theory,we can get The generalized thickness identification model of slit width by Multiple nonlinear function fitting analysis,comparing the actual value and the model prediction through verification experiment,using T test,the model prediction’s accuracy is proved higher,we can accurately predict workpiece thickness.By using the thickness identification model to identify the thickness of workpiece and adjusting parameters in time,the cutting speed and surface roughness consistency of workpiece with variable thickness can be greatly improved.It provides the premise and foundation for further research on automatic control system of WEDM.