Patent ID: 6089113
Filing Date: 2000-07-18
Classification: B30B,F16H,Y10T

Abstract:
A male screw device, comprising:a shaft;a helical thread around said shaft;an upper surface and a lower surface of said thread;said upper surface of a first thread meeting said lower surface of an adjacent thread at said shaft without interference from any protuberances;at least one of said upper surface and said lower surface including a pattern of undulations designed to create a wedging action on a lubricating oil between said undulations and a female portion in which said screw is threaded, when said screw is rotated within said female portion;said pattern of undulations extending along an entire surface of said at least one;said pattern of undulations having sloped surfaces rising and falling with an incline angle less than 90 degrees; andsaid sloped surfaces being transverse to a sliding direction of said helical thread when said male screw is rotated within said female portion.