Theoretical Justification Of Conditions Of Cutting Temperature Reduction At Grinding Of Materials

This research used an adiabatic rods model to conditionally represent the removable allowance and which are cut by a wheel during the grinding process. Numerical calculations were used to establish that the heating time of an adiabatic rod can be up to 10 times shorter than the time of its contact with the grinding wheel during grinding. This is due to the fact that the heating time of the adiabatic rod increases asymptotically with the course of machining time approaching a maximum value determined by the condition of thermal saturation of the surface layer of the work piece. Calculations have established that the cutting temperature and the depth of heat penetration change under the same law. This implies that a large fraction of heat generated during grinding is transferred to the formed chips, and a smaller heat fraction is transferred to the work piece. Based on this, the formulated equations for determining the maximum values for the adiabatic rod heating time, the depth of heat penetration into the surface layer of the work piece, and the cutting temperature during grinding are obtained. It is found that the maximum cutting temperature during grinding is determined only by the conventional cutting stress and does not depend on the grinding mode parameters and grinding wheel characteristics. It is shown that accounting for the adiabatic rod cutting with the grinding wheel reduces the cutting temperature by more than two times, which brings together the theory and practice of grinding. This makes it possible to provide a new approach for the selection of the abrasive wheel contact time and, accordingly, the grinding mode parameters and grinding wheel characteristics, based on the cutting temperature limits. It is also found that the length of the cut section of the adiabatic rod (equal to the grinding depth) is always greater than the depth heat penetration into the work piece, and the cutting temperature is determined by the length of the adiabatic rod subjected to heat, including its cut-off part.