Development of a technological process for the restoration of piston pins using deforming broaching

Abstract

The article discusses the technological process of restoring the geometric dimensional accuracy of piston pins of internal combustion engines (ICE) due to the expansion of the internal hole by a deforming element. As part of conducting research taking into account the resource of the used plasticity of the processed material, the processing modes are determined, the deformation scheme is selected and the geometry of the deforming element is calculated. The selection of the necessary deformation of the part during processing of the piston pin was carried out under the condition of compensating for wear and ensuring an allowance for subsequent mechanical processing. This made it possible to ensure the necessary processing quality of the pin hole surface layer according to the resource parameter of the used plasticity. The deformation scheme was chosen from the condition of ensuring the geometric accuracy of the pin outer surface, which determines the size and uniformity of the allowance for subsequent processing. For these reasons, a scheme was chosen in which the deformation is carried out by two elements with a change of the support end after the first pass. The optimal geometry of the deforming tool was determined from the standpoint of minimizing errors and preserving the initial length of the pin. The results of the conducted experiments showed that using selected expansion schemes, tensions and geometry of the deforming tool, made it possible to ensure the necessary allowance for the next mechanical processing, as well as the invariance of the part length after processing.

Keywords

• piston pin, expansion of the inner hole, expansion modes, expansion scheme, geometry of the deforming tool, geometric dimensional accuracy