淬火冷却中工件的正放与斜放(一)

How to Place Your Workpiece during oil Quenching(一)

摄像记录了多种试样以正放和不同的斜放方式在油中淬火的冷却过程。研究对比了不同放置方式下试样冷却的快慢和冷却的均匀性。结果表明,和试样正放相比,试样斜放冷却得既快而又均匀。冷却过程中,在水平向下的表面上观测到倒立的气体堆。倒立气体堆的存在极大地减慢了所在表面的冷却速度,在工件上造成了很大的温度差。推测了倒立气体堆的形成机理和演变过程。提出了防止出现倒立气体堆的方法。蒸汽膜内气体的流动规律和中间阶段特性是引起上述现象和差异的原因。它们对试样淬火冷却效果的影响可归结成两类:一是在工件上造成了显著的相对厚度差,二是使形状对称的工件得不到具有相似对称关系的冷却效果。

The oil quenching process of different workpieces placed in straight way and other various inclined ways were videoed. This study compared the cooling rate and evenness of the workpieces under different placement ways. The results show that compared with straight sample, inclined sample can be cooled down faster and evenly. During the cooling process, an upside - down heap of gas is observed at the downwards -facing horizontal surface. The existence of the upside - down heap of gas greatly decreased the cooling rate of the downwards - facing horizontal surface, thus led to a great difference in temperature between different areas of the workpiece. This study also presumed the formation mechanism and evolution process of the upside - down heap of gas, and a method for preventing the emergence of it is put forward. The flowing rule of gas inside the vapor blanket and the middle stage properties are the reasons for the above mentioned phenomena and differences. The cooling effect of all above tests revealed two characteristics： （ 1 ） significant relative differences in thickness occurred between different parts of a workpiece; and （2） symmetrically shaped workpiece can not receive corresponding symmetrical cooling effect.