Finite Element Analysis of Thermal Behaviour in Metal Machining (2nd Report, Determination of Energy Balance and Its Application to Three-Dimensional Analysis)

摘要

An inverse analysis approach using the finite element method is proposed to determine the energy balance or the energies flowing into a tool, workpiece and chip per unit volume of material removed in two-dimensional machining. Once the energy flow rates are obtained, a three-dimensional temperature distribution for complicated tools such as an end mill can be analysed easily and efficiently. The method proposed is employed to clarify the effect of thermophysical properties on the energy balance. The energy flowing into the tool is most enhanced when a low-thermal-conductivity workpiece is machined by a high-thermal-conductivity tool with a coolant; wet turning of titanium alloy by a diamond tool is a typical case. It is found that temperature change of a carbide square end mill ranges from 400 to 800℃ in titanium machining at a cutting speed of 314 m/min because of a low energy flow rate into the tool of around 0.04 and the action of a coolant. The suitability of the present method is confirmed by comparison with the Loewen-Shaw model as well as by temperature measurement.