Patent ID: 8220353
Filing Date: 2012-07-17
Classification: F16H,Y10T

Abstract:
1. A screw device comprising: a screw shaft having an outer surface with a rolling-element rolling groove spirally formed thereon; a nut having an inner surface with at least one one-turn groove formed thereon including a loaded rolling-element rolling groove of less than one turn facing the rolling-element rolling groove of the screw shaft and a return groove connecting both ends of the loaded rolling-element rolling groove; and a plurality of rolling elements disposed between the rolling-element rolling groove of the screw shaft and the one-turn groove of the nut, wherein the loaded rolling-element rolling groove and the return groove that has a back lead which is reverse to the lead of the loaded rolling-element rolling groove are first formed in a flat plate by cutting so that the groove widths and depths of the loaded rolling-element rolling groove and the return groove in the flat plate are set larger than the groove widths and depths of the loaded rolling-element rolling groove and the return groove when a nut is formed into a ring and the nut is formed by bending the flat plate into the ring.