Dimple processing method using rotary cutting tool, and rotary cutting tool for dimple processing

A dimple processing method for forming dimples on a workpiece with a rotary cutting tool, the method comprising:

• (a) rotating the rotary cutting tool about a longitudinal axis of the rotary cutting tool and moving the rotary cutting tool along a workpiece in a feed direction oriented orthogonal to the longitudinal axis, wherein the rotary cutting tool has a plurality of cutting edges on a radially outer surface of a rod-shaped main body of the rotary cutting tool, wherein the plurality of cutting edges are arranged axially side by side on a lead edge line of the rotary cutting tool, and wherein the lead edge line extends helically about the longitudinal axis;
• and
• (b) moving the rotary cutting tool relative to the workpiece in an axial direction parallel to the longitudinal axis during step (a) to form a plurality of dimples on the workpiece, wherein the plurality of dimples are spaced apart relative to each other on the workpiece, and wherein a first set of the plurality of dimples are arranged side by side in the feed direction and are offset in the axial direction while partially overlapping with each other in the axial direction;
• wherein the workpiece includes a concave inner wall or a convex outer wall, wherein the concave inner wall or the convex outer wall has a cylindrical or a circular arc cross-section;
• wherein the rotary cutting tool moves along the workpiece with the longitudinal axis oriented parallel to the inner wall or the outer wall of the workpiece, and
• wherein the plurality of dimples are formed on the inner wall or the outer wall as the rotary cutting tool is moved simultaneously in the feed direction and the axial direction along the inner wall or the outer wall of the workpiece while the rotary cutting tool is rotated about the longitudinal axis.