Improvements in shot blasting to increase the surface peak density of auto-industry steel sheet

The introduction of metal curtains around the turbine of the shot-blasting machine for incising the surface of working rollers improves its performance. The curtains are placed perpendicular to the plane of rotation of the shot-blasting turbine wheel. For the 1700 and 2500 tempering mills in casting and rolling shop 5 at OAO MMK, the dimensions of the curtains and their locations are determined so as to increase the density of the shot blast in incising the rollers and to minimize the screening effect of the shot rebounding from the curtain. Research shows that the shot velocity after collision with the curtain changes not only in direction but in magnitude. These changes depend on the friction between the shot and the curtain surface and also on the angle of attack. Modernization of the shot-blasting machine permits increase in density of the shot blast over the surface of the working rollers in the tempering mills and, correspondingly, in the peak density on the tempered sheet by a factor of 1.22.