PREVENTING PROCESS FATIGUE WHEN FINISHING A PART

Possibilities of preventing the appearance of fatigue cracks during finishing processing of a part by changing the elastic–mechanical characteristics of the workpiece due to the accumulation of fatigue defects preceding the appearance of a crack are considered. Modules of elasticity and shear are considered as characteristics to be controlled under the assumption that the material of the part is isotropic. To control these values, the equation of vibrations of the part is used, which is solved by the numerical method, and the values of E and G are selected, corresponding to the measured displacements of surface points that occur during a given movement of the processing tool. The movements are proposed to be measured remotely. The obtained sequences of estimates of the elasticity and shear moduli form two time series, according to which a long–range forecast is made, and the limiting values of the sequences are calculated with an unlimited increase in time. The fatigue criterion is the reduction of these values at the present or future points in time below a preset value. Depending on the degree of reduction, a decision can be made to reject the part or to correct the technological process with a change in the law of the machining tool motion. The proposed control method can be used in the construction of flexible production systems.