| Popis: |
Shot blasting consists in hardening of the parts surface layer or workpieces with a stream of solid particles, mainly in the form of hardened steel balls. The purpose of the work is to develop and test a method for calculating the parameters of an elastic-plastic dynamic contact during shot blasting of parts based on mathematical modeling. The research technique is based on the consideration of a three-stage model of workpiece deformation under elastic-plastic impact by a steel spherical indenter. At the initial stage, the deformation is carried out elastically. Then, under some dynamic load, in the near-surface layer of the impacted body, a region of plastic state is generated, surrounded by an elastically deformable material. With a further increase in the dynamic load above a certain characteristic value, the region of the plastic state comes to the surface of the impacted part. Subsequently, the process is characterized by elastic-plastic indentation of the indenter (shot) into the impacted part. A method for upper calculating estimate the parameters of the dynamic contact of steel shot with parts based on the energy theory of elastic-plastic impact has been developed. To separate the elastic and plastic components of the deformation energy, the velocity recovery factor upon impact was used. The deformable material is accepted at the final stage of deformation as an ideal elastic – plastic material obeying the Prandtl’s scheme. Analytical dependencies convenient for practical use are obtained, which allow one to make calculating estimate of the depth and diameter of the imprint. Estimated calculations of the depth of the indentation depending on the speed of exposure to steel shot for shot blasting of a number of structural carbon steels have been performed. The results of the research can be used in the educational process in the preparation of engineering personnel of the machine-building profile, as well as in engineering practice. |
