Thermal performance analysis of phase change heat storage grinding wheel in high-efficiency dry grinding

A large amount of grinding heat is generated during the high-efficiency grinding process, which causes workpiece burnout. Although the utilization of a significant quantity of coolant can lower grinding temperature, it inevitably leads to environmental pollution and damages the health of operators. To reduce coolant usage, it is worth considering reducing the grinding temperature by enhancing the thermal performance of grinding wheels. In this study, a new type of phase change heat storage grinding wheel (PCHS grinding wheel) with a high heat transfer coefficient and large heat capacity is developed utilizing the boiling heat transfer principle and heat storage technology, whose structure and working principle are explained. In addition, a visual device was made to simulate the internal heat transfer and heat storage process of PCHS grinding wheels, and the effects of heat flux, injection amount of working fluid, heat dissipation conditions, and heat capacity on the boiling heat transfer coefficient, start-up time of working fluid entering the boiling heat transfer state, and grinding temperature control are analyzed. Eventually, a comparative experiment of dry grinding 45 steel was carried out. Results show that the boiling heat transfer coefficient of PCHS grinding wheels is in the range of 1000-7000 W/m2<middle dot>degrees C, the start-up time is 5-8 s, and increasing the heat capacity of grinding wheels can effectively slow down the heating rate. Besides, the grinding temperature is reduced by 22% compared with the maximum temperature of 375 degrees C when using traditional grinding wheels, and the heat transfer coefficient is increased by 2-3 times, which shows that improving the thermal performance of grinding wheels has significant advantages in reducing grinding temperature.