Determination of the allowance for grinding with flap wheels after shot peen forming

Abstract

Shot peening is widely used in forming long panels and sheaths. Due to the impact of shot on the processed surface, the specific microgeometry is formed, the characteristic feature of this microgeometry is the numerous dimples of shot with different diameters and depths. The presence of these dimples causes deterioration of the surface roughness parameters. Therefore, after shot peening the mandatory requirement is implementation of surface grinding with flap wheels for partial removal of the shot dimples. Allowance for grinding depends on the requirements for the quality of the surface of the part. As a rule, the depth of dimples in magnitude significantly exceeds the valleys of micro-irregularities formed owing to previous treatment. The value of the assigned allowance for grinding depends on the requirements for the quality of the surface of the part. As a result of grinding on the treated surface, a new microrelief is formed in the shape of a combination of traces of the impact of abrasive grains of flap wheels and the remains of the dimples from the shot peening. Since the dimples have a spherical shape with a much larger radius of curvature than their depth, they have a special effect on the amount of metal removed and on the roughness of the treated surface. The paper presents an analytical description of the process of quantitative removal of metal and the formation of roughness during grinding with flap wheels of the surface treated with a shot peening. Based on the results of research, mathematical models are constructed to determine the amount of material removed from the surface treated with shot peening during grinding with flap wheels, and a numerical method for determining the allowance for obtaining the required roughness is proposed.