• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2023, Vol. 59 ›› Issue (23): 343-357.doi: 10.3901/JME.2023.23.343

Previous Articles     Next Articles

Heat Transfer Mechanism and Convective Heat Transfer Coefficient Model of Cryogenic Air Minimum Quantity Lubrication Grinding Titanium Alloy

LIU Mingzheng1, LI Changhe1, ZHANG Yanbin1, YANG Min1, CUI Xin1, LI Benkai1, GAO Teng1, WANG Dazhong2, AN Qinglong3   

  1. 1. School of Mechanical and Automobile Engineering, Qingdao University of Technology, Qingdao 266520;
    2. School of Air Transportation, Shanghai University of Engineering Science, Shanghai 201620;
    3. School of Mechanical and Power Engineering, Shanghai Jiao Tong University, Shanghai 200240
  • Received:2023-04-14 Revised:2023-09-12 Published:2024-02-20

Abstract: Thermal damage of workpiece surface in titanium alloy grinding has become an urgent technical problem. The green clean minimum quantity lubrication technology has been applied to auxiliary grinding of titanium alloy, but it still has the defects of insufficient heat dissipation ability and limited lubrication antifriction ability. Using cryogenic air instead of normal temperature air to carry trace lubricating oil can significantly improve the heat transfer and lubrication performance of oil film in grinding zone. However, some scientific problems such as liquid film heat transfer law, workpiece surface temperature field distribution and evolution law of cryogenic lubricating oil physical characteristics still need to be revealed. Based on this, the evolution law of low temperature physical characteristics of lubricant is studied, and the quantitative mapping relationship between cold air temperature and physical parameters of lubricant is established. The heat transfer law of liquid film on workpiece interface of grinding wheel is analyzed and the theoretical model of heat transfer of liquid film in grinding zone is established. Furthermore, the model of convective heat transfer coefficient of lubricant under different cold wind conditions is established. The convective heat transfer coefficient of liquid film and the heat transfer performance of grinding titanium alloy assisted by cryogenic air minimum quantity lubrication are verified. The results show that the theoretical value of convective heat transfer coefficient is in good agreement with the measured value, and the error is 8.5%. The variation trend of the workpiece surface temperature is consistent with that of the theoretical value, when the cryogenic air temperature is -10 ℃. when the grinding depth is 30 μm and the cryogenic air temperature is -40 ℃, the error is 7.7%. The calculation accuracy meets the requirement. The results provide technical support for improving the surface integrity of titanium alloy grinding with cryogenic air minimum quantity lubrication.

Key words: grinding, titanium alloy, minimum quantity lubrication(MQL), cryogenic air, heat transfer mechanism

CLC Number: