Development Of The Phase Change Heat Storage Super-hard Abrasive Grinding Wheel And Experimental Study On Dry Grinding

As an important part of modern advanced processing technology,high efficiency grinding has been widely used in aerospace,automotive,precision machinery/equipment,marine,defense and other fields.However,while improving the material removal rate,high grinding temperature is prone to occur during the high efficiency grinding process,which leads to thermal damage on the surface of the workpiece,which is more prominent in the processing of high-strength and toughness difficult-to-cut materials such as superalloys and titanium alloys.Although increasing the amount of coolant and jet velocity can effectively reduce the grinding temperature,the extensive use of coolant will also bring some negative problems,such as damaging the health of operators,improper disposal of waste liquid,polluting the environment,and greatly increasing the cost of use,which are contrary to the requirements of green processing and sustainable development.Based on the above problems,this paper attempts to turn the cooling focus to the grinding wheel.By using the phase change heat storage technology to improve the thermal performance of the grinding wheel,a new type of super-hard abrasive grinding wheel-Phase change heat storage grinding wheel with high heat transfer coefficient and large heat capacity is developed.The new grinding wheel can realize the enhanced heat transfer in the grinding arc area during the grinding process,thereby reducing the grinding temperature,which confirms the cooling effect and application prospect of the phase change heat storage grinding wheel under dry grinding conditions.The specific research contents are as follows:(1)According to the requirements of thermal performance,structural strength and service performance,the structure design of phase change heat storage grinding wheel is completed.The working principle of phase change heat storage grinding wheel in grinding process is expounded,and the equivalent heat transfer coefficient and heat capacity are analyzed.In addition,a leakage detection and injection platform was built to realize the accurate injection of the annular cavity of the grinding wheel.Finally,the electroplated CBN phase change heat storage grinding wheel was prepared.(2)An equivalent thermal performance analysis device was designed and fabricated to simulate the internal heat transfer/storage process of the phase change heat storage grinding wheel.By monitoring the temperature changes and air pressure changes at multiple locations in the device,the thermal properties of the phase change heat storage grinding wheel was analyzed.It is confirmed that the heat transfer performance of the grinding wheel can be improved by means of phase change convective heat transfer,and better heat transfer performance can be obtained by using liquid working medium with low boiling point and low latent heat of vaporization.In addition,the heat transfer coefficient of the grinding wheel mainly depends on the boiling heat transfer coefficient on the inner wall surface of the outer circle of the grinding wheel.On this basis,the effects of different heat flux,liquid injection volume and heat dissipation conditions on boiling heat transfer coefficient and boiling heat transfer start-up time were investigated.At the same time,the greater the heat capacity of the grinding wheel itself,the better its heat storage capacity,and the slower the system temperature rise caused by heat transfer,which is also important for controlling the grinding temperature.(3)The comparative experiments of creep feed deep dry grinding of 45 steel and GH4169 nickel-based superalloy were carried out by using the developed phase change heat storage grinding wheel and the traditional grinding wheel,and the arc zone temperatures under different grinding depths were compared.The test results show that the temperature of the arc zone decreases by about 38 % when grinding 45 steel,and the temperature of the arc zone decreases by about 18 % when grinding GH4169 nickel-based superalloy.It is confirmed that the phase change heat storage grinding wheel can strengthen the heat transfer in the grinding arc zone during the dry grinding process,thereby reducing the grinding temperature.In addition,the surface morphology of the grinding wheel and the surface roughness of the workpiece after dry grinding are further analyzed.