The Resarch Of Heat Transfer Theory By Noanfory Jei Lubrication And The Evaluation Of The Surface Integrity In Grinding

The grinding process generates an extremely high input of energy per unit volume of material removed. Virtually all this energy is converted to heat, which can cause high temperatures and thermal damage to the workpiece such as workpiece burn, phase transformations, undesirable residual tensile stresses, cracks, reduced fatigue strength, and thermal distortion and inaccuracies.In addition, the high grinding temperature rise will lead to the dimensional and shap accuracy of workpiece and dramatically life of wheel.Therefore,how to control the high grinding temperature and workpiece burning is very important.There is an important issue to study the theory of grinding and improve the integrity of workpiece.In traditional grinding usually use a large number of grinding fluids to control the grinding temperature.But a little grinding fluids can enter grinding zone for air flow layer around the high speed grinding wheel.So plentiful grinding fluids only can cool the substrate of workpiece,and then make a lot of pollution and waste.Environmental protection and the need for cost-reduction have all promoted the development of new environmentally conscious machining processes.Recent years,the minimum quantity lubricant(MQL) is a green machining way . The use of MQL is of great significance in conjunction between large cutting fluids application and dry machining. It can reduce the amount of frictional heat generation and provide some cooling in the tool-workpiece interface and hence keep the workpiece temperatures lower than those in a completely dry machining. Experimental results showed that MQL provided effective lubrication but insufficient workpiece cooling with conventional abrasive wheels. The recent development of nanofluids provides alterative cutting fluids which can be used in MQL grinding. The advanced heat transfer and tribological properties of these nanofluids can provide better cooling and lubricating in the MQL grinding process, and make it production-feasible.The main contents of this paper is MQL grinding of zirconia using nanofluids as the heat transfer medium.The following is the main content of the article:1. The research of heat transfer enhancement by nanofluids jet lubrication.It presents formation and characterization of nanofluids. The methods of nanofluids synthesis are introduced and several different types of nanofluids are formulated. The method used how to measure the thermal conductivity of nanofluids.2. It presents the experimental work of MQL grinding using conventional abrasive wheels. Both water based and oil based nanofluids were employed in MQL grinding and the performance was evaluated in terms of grinding force, G-ratio, and surface roughness, etc.3. There focuses on heat transfer in grinding. Based on thefinite element method,the temperature field of ceramics grinding conditions are modeled and analyzed.Temperature experiments of zirconia is researched under different grinding conditions and verified the finite element results above.4. The evaluation of the surface integrity in grinding.The microscopic photos can display the quality of grinding surface in all conditions.The parts of zirconia grinding will control the quality of surface after analysising.