Calculation of residual stresses from burnishing taking repeated deformations into account

It is shown that the introduction of CNC grinding machines requires a constant assessment of the state of the technological system taking into account the dynamics of the process based on automatic control of the machining process. The article substantiates the necessity of taking repeated deformation into account during the technological operation of burnishing (deforming broaching), and the experimental distributions of the residual stresses during burnishing are presented. In order for designers to have the right to set residual stress requirements on drawings, technologists must be able to form them and, therefore, model them. A simulation of residual stresses in a hollow thick-walled cylinder during burnishing which takes into account secondary deformations and re-deformation is presented and areas with plastic loading and elastic unloading or elastic loading and elastic unloading are examined. Examples of modeling residual stresses and the results of the calculated determination of the circumferential residual stresses in a hollow cylinder according to mathematical models are given; recommendations are given in this connection on the appointment of a number of burnishing rings on the burnishing tool; it is shown that two are sufficient to form the necessary distribution of residual stresses in the surface layer, and a third ring provides roughness. The features of distribution of circumferential compressive residual stresses in the areas of secondary and repeated deformations are considered; repeated deformations appear in the near-surface layer adjacent to the treated surface, i.e. the residual stresses from the repeated deformation are superimposed on the secondary residual stresses. Detailed conclusions on the effect on residual stresses in the near-surface layer of pressure changes (interference) during burnishing, the changes in the wall thickness of the cylinder, and changes in the yield strength of the processed material$ simulation results donn't contradict experimental data.