Study the possibility of controlling the magnitude and distribution of residual stress in the surface layer of the product after the process double duplex burnishing

In the first stage, on the semi-fabrication surface, one embossed regular asperities about needed outline (triangular, rounding, rounding-linear, trapezoid or other) and parameters depending from the needed properties of the article's surface layer. In the second stage the asperities are burnished (smooth burnishing), till the needed asperities equalized. Burnishing rolling process in the duplex type consist of two stages. In the first stage, on the semi-fabrication surface, one embossed regular asperities about needed outline (triangular, rounding, rounding-linear, trapezoid or other) and parameters depending from the needed properties of the article's surface layer. In the second stage the asperities are burnished (smooth burnishing), till the needed asperities equalized. It causes shaping own stresses, which will be occurred on the needed depth. In the dependence from the destination of the parts, it is necessary to give adequate values of the maximum stresses and adequate depth of their occurring. In this aim burnishing rolling process type duplex must be realized repeatedly, but in the next stages of embossing asperities, their height is lower than the previous, and the outline of the asperity and its geometrical parameters depends from the needed layout of the own stress in the product. In the proposed treatment technology, in the finishing (the last) operation of duplex burnishing, it is possible to shaping needed value of the maximum stress (σmax(1)), depth of their layout (h0(1)) and layout of the own stresses, but also shaping needed geometrical structure of the product surface. Analysis of the possibility of own stresses steering can be realized by changing factors: regular outline of the asperity (triangular, rounding, rounding-linear) and their parameters (height, vertical angle, rounding radius), asperities space, depth of pile and smooth burnishing, number of upcoming one by one crossing in hybrid burnishing (embossing of asperity and their burnishing), position of the burnishing tools in the next steps. The article presents the results of experimental and numerical (using FEM) of a double burnishing duplex in terms of the possibility of controlling the magnitude and distribution of residual stress in the surface layer products. © 2016 Trans Tech Publications, Switzerland.