Simulation And Experimental Study On Electro-discharge Dressing Of Superabrasive Grinding Wheels Using Different Dielectric

The electro-discharge dressing method(EDD)is a dressing method with high efficiency,high precision and low cost.However,the dressing of coarse-grained superabrasive wheels is limited by factors such as the threshold discharge gap,and it is difficult to obtain well effect using traditional EDD method.In order to optimize the effectiveness and efficiency of EDD in dressing coarse-grained wheels,this paper proposes a method of powder-mixed EDD that uses SiO₂ powder mixed deionized water mist instead of traditional dielectric.The feasibility and advantages of this method are verified through the combination of theoretical analysis and experiment using pure deionized water mist and air as the contrastive dielectric.The main contents are as follows:(1)Describition of the characteristics and difficulties of EDD in dressing coarse-grained superabrasive grinding wheels are presented.From the perspective of mechanism and technology,the research and development of EDD is summarized.A method of powder-mixed EDD using SiO₂ powder mixed deionized water mist as dielectric is proposed,and the main frame and content of this paper are introduced.(2)Based on the mechanism of material ablation in EDM,the theoretical analysis of dielectric properties and discharge characteristics of powder mixed deionized water mist was carried out.Using bronze binder as the material,a heat transfer model of anode workpiece is established,and the thermal energy generated by the discharge channel is simplified as a Gaussian heat source to carry out the simulation of the temperature field and the ablation craters.The influence of the SiO₂ powder mixed deionized water mist on the discharge gap and the process of material ablation is quantitatively summarized.(3)The improved discharge gap measurement equipment is built,and the electro-discharge gap measurement experiment is conducted to analyse the effects of different dielectric including compressed air,deionized water mist and SiO₂ powder mixed deionized water mist as well as different duty ratio,open circuit voltage and peak current on the discharge gap.This experiment also comfirms the best discharge parameters for the dressing experiment of wheels.(4)A dressing and grinding experiment equipment of grinding wheels is built,and the effects of different dielectric including compressed air,deionized water mist and SiO₂ powder mixed deionized water mist on the surface morphology and the height of the grains of wheels dressed,and the dressing efficiency,the distribution of elements on the surface and other indicators are compared through experiments.The feasibility,higher efficiency and better effect of powder-mixed EDD are verified in those experiments,and the improvement of powder-mixed EDD on the grinding performance of wheels is verified in the experiment of grinding YG8 sample pieces.