A study on thermal performance of revolving heat pipe grinding wheel

Abstract

The heat generated in the grinding process can result in high temperatures in the grinding contact zone, and result in defects to both the workpiece and the grinding wheel. Typically, coolants are used to transfer heat from the contact zone. This process, however, is not satisfactory as coolants often lose efficacy due to film boiling and can result in adverse health and environment effects. A novel cooling method that incorporates a two phase revolving heat pipe within the annular disk of the grinding wheel has been proposed. In this paper, the heat transfer mechanism in the evaporator section and the condenser section was analyzed using the volume of the fluid (VOF) model in ANSYS/FLUENT. The influence of different evaporator geometry, input heat flux, filling ratio and rotational speed on the heat transfer performance are reported here. In the evaporator, nucleate boiling is suppressed and replaced by laminar convection heat transfer as the rotational acceleration exceeds 1033g. The ideal filling ratio is about 17% with a corresponding heat transfer coefficient of 6091 W/(m2·K) and the appropriate heat flux is in the range 2500 to 500,000 W/m2. Grinding experiments with both revolving heat pipe cooling and coolant cooling are performed, and the results analyzed in terms of grinding temperature and workpiece quality. The average grinding temperature was found to be under 120 °C with revolving heat pipe cooling, while temperature spikes as high as 800 °C with severe plastic deformation and grain refinement beneath the workpiece surface was found with coolant cooling.