英语翻译In Fig.6 the temperatures within the workpiece at variou

英语翻译
In Fig.6 the temperatures within the workpiece at various depths below the surface are shown,as calculated for all grinding wheels for different depths of cut.These temperatures
are taken for the same step of the analysis shown in Figs 4 and 5 and are shown underneath the grinding wheel where the maximum temperatures are reached.In the same diagrams,the three critical temperatures for the 100Cr6 steel are also indicated.From Fig.6,the theoretical depth of the heat-affected zones can be determined for each wheel used and depth of cut.In Fig.6(a) it can be seen that there is no austenitic transformafion since the temperatures are not high enough.On the other hand,when grinding with wheel 6 and for a depth of cut of 0.05 mm,the austenific transformafion temperature is exceeded in the layers at depths up to 0.1 mm below the surface (see Fig.6(b)).A diagram is presented in Fig.7 to predict approximately the temperature on the surface and within the workpiece for grinding wheel 6 for different values of equivalent chip thickness,h,designated as The equivalent chip thickness includes the effect of the three grinding parameters and may be more suitable than the depth of cut for use for the optimisation of the grinding parameters.In order to observe or to limit its crifical value,it is not necessary to decrease the depth of cut and it is also possible to suitably change the grinding conditions.In the same diagram,the regions within the critical temperatures are also indicated by contour bands so that the heat affected zones can be predicted.Such diagrams can also be constructed for the other wheels,using results obtained from the finite-element model; they may be used as a guide for selecfing the optimal grinding conditions.
5.Conclusions
The commercial implicit finite element code MARC has been employed to simulate the grinding of hardened steels with aluminium oxide grinding wheels and the following conclusions may be drawn:
1.The maximum temperature and the distribufion of the temperature fields in the workpiece can be calculated successfully with the proposed model when the power or the tangential force per unit width of the workpiece during the process is known.
2.Using the temperature fields derived from the model,the heat-affected zones of the workpiece can be predicted,considering the critical temperatures for tempering,and martensitic and austenitic transformation.