Influence of the time discrepancy (TD) between the first grinding wheel cut-out and the second cut-in of two-pass grinding on the hardened layer

Abstract

A grind-hardening experiment on nodular cast iron QT400 was done with a surface grinder. The effects of the time discrepancy(TD) between the first cut-out of the grinding wheel and the second cut-in of the two-pass grinding on the grinding force, microstructure, micro-hardness and uniformity of the hardened layer depth were studied. Then, by using the measured tangential grinding force to establish a simulation model of the grinding temperature field. We concluded that increasing TD with the same grinding parameters can reduce micro-hardness and the depth of the hardened layer; indeed, the uniformity of the hardened layer can also be improved. However, the change of TD has no noticeable influence on the grinding force and microstructure of the hardened layer. The simulation results show that with the same grinding parameters, reducing the TD can increase the temperature of the workpiece in the second grinding. The experimental results are consistent with the simulation results, and the relative error of the hardened layer depth is 9%. Under the consistent grinding parameters, when TD = 6 s, the hardened layer depth is moderate and its uniformity is good.