Design and Development of Novel Multipoint Epicyclic Superfinishing Tool

Abstract

As the field of superfinishing is progressing every day, the need for controlled and precisely finished complex industrial as well as medical components is emerging rapidly. However, the conventional finishing processes have limited capability when it comes to superfinishing. This work presents the design and development of a novel multipoint superfinishing tool. It utilizes magnetically energized hemispherical balls of polishing fluid formed at the tip of the tool to finish magnetic as well as non-magnetic materials using specially prepared magnetorheological polishing fluid. A modified epicyclic gear train mechanism is used for the design of the new tool with the shaft attached to the carrier and sun gear modified to be the non-movable integral component of the shaft with the cavity in the end for permanent magnet placement. The three planetary gears have extended shafts at both the ends with one end force-fitted to the carrier with a bearing and another end has the cavity for the placement of permanent magnets. The three planetary gears mesh with the ring gear which is directly mounted on the shaft. When the spindle/shaft rotates, the ring gear is kept stationary, and the planetary gears rotate around the common axis as well as spins on their respective axes simultaneously. This way the tool becomes multipoint and has a bigger diameter than the existing tools and can finish much larger area in the same period without affecting its ability to form the abrasive laden polishing fluid balls at the tip. Magnetic field analysis is done for the tool with the permanent magnets to simulate for the magnetic field interaction between tool and ferromagnetic workpiece. The finishing process is carried out on the 3-axis CNC vertical milling machine for the precise control of the working gap (the gap between workpiece and tool) to control the applied finishing forces.