Characterization And Control Of The State Of The Passivating Film On Wheel Surfaces In ELID Grinding

Demands for high quality surface finish, dimensional and form accuracy are required for hard and brittle materials, especially the ceramic material. It is very difficult to achieve these using conventional grinding methods. Electrolytic In-process Dressing (ELID) grinding is one new and efficient method that uses a metal-bonded diamond grinding wheel in order to achieve a mirror surface finish especially on hard and brittle materials. When pre-dressing starts, a passivation layer composed of oxidized bonding material is formed on the wheel surface. This passivation layer reduces the electrical conductivity of the wheel surface and prevents excessive flow-out of the bonding material from the wheel. When grinding begins, diamond grains wear out and the layer also becomes worn out. As a result, the electrical conductivity of the wheel surface increases and electrolytic dressing restarts with the flow-out of bonding material from grinding wheel. The protrusion of diamond grains from the grinding wheel therefore remains constant. This cycle is repeated during the grinding process to achieve stable and efficient grinding. So the token and control of the passivation layer is very important because of its critical effect of the quality in grinding.In this paper, based on the Fuzzy Neutral Network theory, a computer system that controls the state of the passivation layer has been set up. The experiments prove that this system can improve the grinding efficiency and precision obviously. First, a data-acquisition system has been built to get the process parameters and signals based on Labview software and DAQ card. A data-output system is built to achieve the voltage-control process. Using the acquisition system, three signals, electrical current between the wheel and electrode, force of grinding and acoustic emission, are obtained. According the three signals, proper samples are chosen to accomplish the training of the Fuzzy Neutral Network and a proper output is gained to adjust the output voltage. This system can accomplish the token and control of the passivation layer and achieve the continuous process of ELID grinding.