The Inverse Numerical Solutions of the Nonlinear Heat Transfer Problem in Electrical Discharge Machining

Abstract

During the process of electrical discharge machining (EDM), it is very difficult to measure the arc power exerted on the workpiece due to the capability of the measuring instrument. Alternatively, there is another approach to overcome this difficulty. By measuring the temperature on the surface of a machined dent together with the inverse method, the arc power could be calculated. The latent heat effect is neglected and the nonlinear least square method by Beck is incorporated to establish the numerical model. In this research, the arc power and thermal conductivity are unknown parameters and will be solved inversely under the considerations of different numbers of measuring points, different measuring positions, various time increments, and various discharging time. The results show the minimum solution error occurring when measuring temperature approaching the edge of the dent and taking small time increments.