Development of Micro-Dimple Forming for Inner Surface of Pipe

Abstract

A micro-dimple forming process using a forming tool was developed to improve the antiseizing properties of sliding surfaces of mechanical components and to reduce frictional resistance. This process combines a roller-burnishing process and a ball-burnishing process. The features of the process are as follows. A regular alignment of dimples can be achieved at a high speed using conventional machines such as lathes, milling machines and drilling machines. The alignment of dimples formed on the inner wall of metal pipe can be controlled by varying tool geometry and process conditions. This process is applicable to metals with a hardness lower than 400HV, including steel, aluminum and copper alloys. Bump-free dimples can be formed because roller burnishing after ball burnishing flattens bumps around the dimples. The thin layer of the processed surface is work-hardened with compressive residual stress.