Simulation modelling of dynamic processes due discontinuous frictional treatment of the flat surfaces

Friction treatment refers to surface strengthening (hardening) methods using highly concentrated energy sources. In the course of this processing in the surface layers of the processed surfaces of parts the strengthened layer with nanocrystalline structure is formed. The formed layer has specific physical, mechanical, chemical properties, as well as improved performance properties, which are significantly different from the base metal. A highly concentrated energy source is formed in the contact area of the tool-part due to the high-speed friction (60–90 m/s) of the tool on the treatment surface. Frictional treatment of flat parts according to the kinematics of the process is similar to grinding. The strengthening process was carried out on an upgraded surface grinder. The tool is a metal disk made of stainless-steel. Transverse grooves are formed on the working surface of the tool to intensify the process of forming a strengthened (reinforced) layer with a nanocrystalline structure. The grooves form additional shock loads in the contact area of the tool-treatment surface of the part. These shock loads increase the shear deformation of the metal of the parts’ surface during treatment, which affects into formation the quality parameters of the parts’ surface and surface layer. To study the friction treatment process, the calculation scheme of the elastic system of the machine was developed. A simulation model for the study of dynamic processes that take place during the friction treatment of flat surfaces was built. This model gives possibility to determine the displacements and velocities of the machine table on which the part is fixed and the tool, and to determine their mutual displacement and also calculate the reaction of the machine table.

Topography of the strengthened cylindrical surface after frictional continuous treatment

Friction treatment refers to methods of surface strengthening (hardening) of the parts’ working surfaces using highly concentrated energy sources. Concentrated energy flow is formed during high-speed friction of the tool on the treated surface in the area of their contact. A strengthened (reinforced) white layer with a nanocrystalline structure is formed in the surface layer of the treated surface. Friction treatment of cylindrical surfaces of samples made of steel 41Cr4 (hardening and low-temperature tempering) was made on a lathe, and the device for the autonomous drive of the strengthening tool was installed instead of a toolpost. The tool was used with a smooth working part and with transverse grooves on the working part. Experimental researches of the strengthened surfaces’ topography were carried out on a profilometer “TALYScan 150” (Taylor Hobson Ltd, UK). The obtained data were processed in the software “Digital Surf MountainsLab Premium 8.2”. After friction treatment by using the tool with transverse grooves on its working part on the treated surface more evenly distributed peaks than after friction treatment by using the tool with the smooth surface. Analysing the spectral density of the peak’s distribution on the treated surfaces, it can be noted that after friction treatment by using the tool with transverse grooves, the area of the spectra is the lowest in comparison with friction treatment by using the tool with a smooth working part. When using the tool with cross grooves on its working part during frictional treatment allows to receive the best parameters of quality of the treatment surface in comparison with frictional treatment by the tool with a smooth working part. The parameters of the load-bearing capacity curve of the surface treated by the tool with transverse grooves on its working surface are better than after frictional treatment by the tool with a smooth working part. The treated surface by the tool with transverse grooves has a more favourable surface for wear, which was confirmed by research on wear resistance.