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US 5,373,754 AGranted
Ball screw
AssigneeNippon Thompson Co., Ltd.
InventorSeiji Takei
Life of this patent
Estimating the term…
Abstract
A ball screw that, together with contributing to reduction of the cost of the device wherein it is incorporated as a feed mechanism, eliminates the need for adjustment work performed to maintain the operation state of the object being operated, for example, an automatic door. The thread pitch of a threaded portion of a screw shaft is varied from one end to the other.
Claims4
A ball screw comprising:
- a screw shaft having a plurality of continuous screw threads formed therein;
- a nut that is supported on said screw shaft, a plurality of circular grooves formed in an inner circumference of said nut at a predetermined pitch and, a number of balls equal to a number of said screw threads arranged within each of said circular grooves, each of said balls being engaged with a respective one of said screw threads of said screw shaft;
- wherein, the thread pitch of said screw threads of said screw shaft varies along the length of said screw shaft.
Dependencies are inferred from the claim text.