预加热磨削强化均匀性实验研究

Experimental Study on Uniformity of Preheated Grind-hardening

针对磨削强化过程中磨削强化层沿工件磨削方向分布不均匀以及磨削后工件表面产生变形的情况,提出了一种基于温度补偿的磨削强化层均匀性改善方法.通过铜电极对工件导电加热,并在工件切入端安装304不锈钢垫片,通电后形成串联的闭合回路.利用304不锈钢的电阻率大,导热系数小的特性,在预加热条件下工件切入端形成局部高温,达到对工件切入端进行温度补偿的目的,从而提高切入端的磨削强化层深度,进而提高工件磨削强化层深度分布的均匀性.实验中研究了预加热温度和304不锈钢厚度对磨削强化层分布和工件变形情况的影响规律.实验研究结果表明:磨削力和工件磨削强化层深度随着预加热温度升高而增加;随着工件磨削切入端所加不锈钢垫片厚度的增加,磨削后工件变形减少,同时沿工件磨削方向磨削强化层深度分布的均匀性相应提高.

In this paper,referring to the uneven distribution of the grinding harden layer along the grinding direction and the deformation of the workpiece surface after grinding,a kind of grinding method was put forward based on the temperature compensation to improve the uniformity of the grinding harden layer.The workpiece was electrically heated by a copper electrode with a 304 stainless steel gasket mounted at the cut-in zone of the workpiece,and a closed loop was formed after electrifying.Because the 304 stainless steel is of the high resistivity and low thermal conductivity,the high temperature on the cut-in zone appeared.Thus,the increased harden layer was formed on the cut-in zone,and the uniformity for the grinding harden layer distribution can be also improved.The distribution of grind-hardening layer and the workpiece deformation were studied under the different preheating temperature and different thickness of the 304 stainless steel.The results show that the grinding force and the grinding harden layer depth can be increased under the preheating condition.With the increasing thickness of the stainless steel gasket at the cut-in zone of the workpiece,the deformation of the ground workpiece is reduced.At the same time,the uniformity for the harden layer depth distribution is also improved.