动态淬火介质冷却特性及换热系数的研究

Research on the Cooling Characteristic and Heat Transfer Coefficient of Dynamic Quenchant

为了研究工业生产条件下淬火油在不同流速下的冷却特性曲线及换热系数 ,用超声波多普勒流量计测定了淬火油槽的流速 ,按ISO9950标准测定冷却特性曲线 ,用 1 2 0mm× 1 2 0mm× 2 0mm平板状试样和反传热法测定与计算了换热系数。结果表明 ,随着介质流速的增加冷却特性曲线的冷速最大值及换热系数的最大值均呈增加趋势 ,当搅拌使介质中产生气泡时 ,介质的冷却能力明显降低。最后指出换热系数曲线能更好地反映表面热量传递的真实情况。

In order to investigate the cooling characteristics and heat transfer coefficient of quenching oil at different flow rates under practical condition, the Doppler flowmeter had been adopted to measure the flow rates in given quench tank. The cooling characteristics had been measured in accordance with ISO9950 standard, and the heat transfer coefficients had been measured and calculated with 120mm×120mm×20mm flat samples and by the inverse heat transfer method. The results show that the peek values of cooling curves and of heat transfer coefficient curves also increase with the increment of flow rates. When agitation produces bubbles in quenching oil, it will decrease cooling ability of the quenchant. It is also demonstrated that heat transfer coefficient can perfectly describe heat transfer at the interface between workpiece and quenchant.