IMPROVEMENT OF OFFICIAL CHARACTERISTICS OF THE SURFACE LAYER DETAILS BY APPLICATION OF SURFACE PLASTIC DEFORMATION AND GASODYNAMYNAMYNAMINE

Abstract

The article investigates changes in the characteristics of the surface layers of parts processed by methods of surface plastic deformation (SPD). It is shown that at SPD the strength and hardness characteristics of the material increase and residual compression stresses are formed. On the basis of the study of the stress-strain state of the material at the SPD, its non-monotonicity is established, which is manifested in the gradual change of sign of the components of deformations and stresses. In this regard, a tensor-nonlinear damage accumulation model was used to evaluate the deformability of the material, which takes into account the directional nature of the damage and the anisotropy of the plasticity of the deformed metal. Based on this model, an expression was obtained to determine the plasticity resource used in the case of multi-stage SPD. According to the results of the calculations, it is established that the maximum plasticity resource used in the SPD is at a depth of approximately 0.1 of the diameter of the plastic footprint of the tool, and destruction at full exhaustion of the plasticity resource occurs in the form of peeling of thin plates of appropriate thickness. Recommendations for displacement of the most reinforced layers to the surface of the workpiece are developed, as well as recommendations for limiting deformation by the amount of plasticity resource used. The conducted research allows to assign the optimal modes of SPD at the stage of technological process design. A device for cold gas-dynamic spraying was developed and the possibility of creating antifriction sections using it was investigated. Graphs of dependence of geometrical parameters of the deposited layer on the sputtering distance are constructed and methods and schemes of preparation for deposition of the surface of the workpiece using SPD methods are developed. Experimental cold gas-dynamic spraying was carried out and optimal parameters of the process of spraying of antifriction layers of bronze and metal polymers (pressure, and the temperature of the compressed air and the temperature of the workpiece) on the formed roller surface were determined. A new concept of increasing the contact strength and durability of friction pairs is proposed.