Research On The Mechanism Of Electrical Discharge Dressing Diamond Wheel In Mist-jetting

Electrical discharge dressing and truing of diamond grinding wheel with mist medium is anon-contact and non-traditional promising green technology. It has the advantages ofenvironmental protection and high efficiency, etc. In addition, mist medium reduce thedependence of working liquid. It can be used for high precision grinding machine onlinedressing.Firstly, this paper studied the dielectric breakdown mechanism. Then establish mathematicalmodel of discharge in mist medium based on dielectric breakdown of WZ model. In themathematical model, threshold electric field is an important parameter which influence electricspark discharge path. Mist medium electric field distribution is equivalent to a ball inhomogeneous electric field. Threshold electric field intensity in mist medium is a third ofthreshold electric field intensity in air by gauss’s law. Simulate the discharge path of the electricspark with matlab in different mediums. Then, from the perspectives of fractal theory, the fractaldimension of discharge path is different in different mediums. The value of fractal dimensionreflects energy distribution of a single pulse. The simulation results show that dischargecoefficient of energy distribution is minimum in the mist medium. During the discharge processin mist，the discharge energy is dispersed and energy density of the channel is low. Experimentalresults of dressing diamond wheel in different dielectrics are coincidence with this idea.Due to electrical conductivity, specific heat capacity, thermal conductivity, thermaldiffusivity, oxidation temperature and other aspects of the diamond grits and bond materials inthe bronze bond diamond grinding wheel have significant difference. It has the possibility toremove bond materials selectively. This paper established the model of discharge dressing metalbond diamond grinding wheel. When dressed, the surface temperature of diamond grindingwheel will affect dressing effect. The surface temperature of diamond grinding wheel is relatedto the value of the discharge parameters. So the choice of discharge parameters on dressingresults will have an important influence.In this paper, experiments on dressing bronze-bond diamond grind wheels with differentprocess parameters were carried out on a Die-Sinking Electrical Discharge Machine. Theinfluence of different process parameters on morphology of the diamond wheel, dressingefficiency and chip space were analyzed. Experiments results indicate that the peak current andpulse width are the main factors to affect the surface morphology of diamond wheel and thedressing efficiency. There exiting a rational interval of process parameters on electrical dischargedressing and truing of diamond grinding wheel with mist medium. When the process parameters are in the rational interval, the dressing results are better. Having experiment research on thedressed diamond wheel. The results show that the normal grinding force and tangential grindingforce of the dressed diamond grinding wheel are reduced compared with the blunt diamondgrinding wheel under the same grinding parameters. Namely, the performance of the dressedgrinding diamond wheel has been improved greatly. It shows that electrical discharge dressingdiamond wheel in mist-jetting is completely feasible.