Patent ID: 6108909
Filing Date: 2000-08-29
Classification: B21H,B21J,B21K,F16C,Y10T

Abstract:
A precise groove forming process, said process comprising the steps of:(a) providing a shaft for use in a hydrodynamic bearing of a spindle motor;(b) inserting said shaft between a pair of dies spaced apart, said pair of dies including a first die having at least one groove pattern and a second die;(c) positioning said shaft perpendicular to said at least one groove pattern and at a first pattern position of said at least one groove pattern;(d) clamping said shaft between said pair of dies;(e) simultaneously applying pressure in a vertical direction between said pair of dies and applying pressure in a first horizontal direction to one of said pair of dies so that said shaft rolls in a first direction over said at least one groove pattern from said first pattern position to a second pattern position of said at least one groove pattern;(f) simultaneously applying pressure in a vertical direction between said set of dies and applying pressure in a second horizontal direction to one of said pair of dies so that said shaft rolls in a second direction over said at least one groove pattern from said second pattern position to said first pattern position; and(g) performing steps (e) and (f) until said at least one groove pattern is formed on the outer diameter of said shaft.