微量润滑平面磨削接触区换热机理的研究

磨削接触区材料去除厚度是不一致的,同时,在微量润滑过程中,雾滴之间的运动特征存在差异且易受其他因素的影响,致使整个接触区的磨削温度分布呈现出非线性,换热机理也异常复杂。从雾化机理出发,对影响换热效果的两个关键因素--雾滴直径和雾滴速度进行了分析。依据雾滴在不同壁温处表现出的不同换热特性，将磨削区划分为无沸腾换热、核态沸腾换热、过渡沸腾换热和稳定膜态沸腾换热四个不同的换热区域,建立了微量润滑磨削区的换热系数数学模型。在此基础上，运用有限元技术对微量润滑磨削表面的温度场进行了仿真分析，采用单级热电偶技术测量了磨削温度，发现磨削区仿真温度值与实验测量值吻合较好，表明通过该理论获得的微量润滑磨削表面换热系数是可信的。

Research on Heat Transfer Mechanism in Grinding Zone for MQL Surface Grinding

The material removal thickness in the grinding zone was changing along the grinding direction during MQL grinding. The movement characteristics of the droplets were different and easily affected by the spraying parameters. Therefore, the temperature distribution in the grinding zone was exhibited highly nonlinear characteristics, and the heat transfer mechanism for the MQL surface grinding was extremely complex. The two important factors(namely, the diameter and speed of the droplet) which influenced on the heat transfer in the grinding zone were analyzed according to the atomization mechanism. Based on the difference of heat transfer characteristics for the droplet at different surface temperatures, the grinding zone was divided into four different heat transfer zones: non-boiling, nucleate boiling, transitional boiling and stable film boiling. The related mathematical models of heat transfer coefficient in the grinding zone were established. In addition, the temperature field in the grinding zone was simulated by using the finite element method(FEM) and measured by single pole thermocouple method.It is found that the FEM results and experimental results are very close, which demonstrates that the theory of surface heat transfer coefficient during MQL surface grinding is creditable.