Study on the Dynamic Thermal Contact Resistance and Its Evaluation

本研究旨在了解圆柱表面滚动接触时动态接触热阻（TCR）的物理机制。作为澄清这一复杂现象的第一步，对静接触圆柱面的TCR进行了详细的研究。提出了一种暂态评价TCR的方法，并将其应用于动态情况。该技术用于估算钢（S45C）或铝合金（A6061）轧辊的TCR值。在10 ~ 120 kgf（98 ~ 1 ~ 1 80n）载荷条件下，对直径为60mm、长度为180的接触辊的TCR进行了一系列试验和计算评估。本研究的结论总结如下：(1)实测和估计的总TCR随滚子载荷的增加而减小。(2)在当前条件下，当载荷大于20kgf时，接触线上的微观收缩阻力可以忽略不计。相反，由于热流向接触线收敛而产生的宏观收缩阻力在整体TCR中占主导地位。(3)这种宏观收缩阻力取决于接触线的宽度。宽度估计约为1.4-2.4米，这是赫兹弹性接触理论给出的值。这种差异很可能是由于表面的粗糙度造成的。(4)接触面之间存在的空气的传导传热对总体传热有重要贡献。对于接触线附近非常薄的空气层，稀薄气体效应的考虑也很重要。(5)负责微观收缩阻力的接触电阻层热容量的影响可以忽略不计。这表明圆柱表面在滚动接触过程中的整体动态TCR可以由静态微观TCR加动态宏观TCR来计算，后者可以用传统的计算方法进行数值预测。少

This study aims at understanding the physical mechanisms of dynamic thermal contact resistance (TCR) of cylindrical surfaces in rolling contact. As a first step to clarifying this complex phenomenon, the TCR of statically-contacting cylindrical surfaces has been investigated in detail. A transient method for the evaluation of TCR is developed with a view to applying it to the dynamic case. The technique is used to estimate the value of TCR for rollers made of either steel (S45C) or aluminum alloy (A6061). A series of experimental and computation evaluations is made for TCR of contacting rolls, whose dimension is 60 mm in diameter and 180 in length, under the loading conditions of 10-120 kgf(98-1 1 80 N). The conclusions gained by the present study are summarized as follows :(1) The total TCR measured and estimated decreases with load applied to the rollers.(2) Microscopic constriction resistance at a contact line becomes negligible for the load larger than 20 kgf under the present cond … More itions. Instead, macroscopic constriction resistance due to the heat flow's converging to the contact line becomes dominant in overall TCR.(3) This macroscopic constriction resistance is dependent on the width of the contact line. The width is estimated to be about 1.4-2.4 mes, the value given by the Hertz theory of elastic contact. This discrepancy is likely due to the roughness present on the surfaces.(4) The conduction heat transfer through the air present between the contacting surfaces has an important contribution to the overall heat transfer. The consideration of the rarefied gas effect is also important for very thin air layer near the contact line(5) The effect of heat capacity of the contact resistance layer responsible for the microscopic constriction resistance can be neglected.This suggests that the overall dynamic TCR of cylindrical surfaces in rolling contact may be evaluated from the static microscopic TCR plus the dynamic macroscopic TCR, the latter can be predicted numerically by conventional computational methods. Less