BALL SCREW AND MANUFACTURING METHOD OF NUT FOR BALL SCREW
First Claim
1. A manufacturing method of a ball screw, the ball screw including a screw shaft having on an outer circumferential surface a spiral screw groove, a nut having on its first inner circumferential surface a screw groove facing the screw groove of the screw shaft, a plurality of balls rollably loaded in a spiral ball rolling passage formed by the both screw grooves, and a ball circulating passage to return the balls from an end point to a start point of the ball rolling passage for circulating the balls, the manufacturing method comprising:
- forming a concaved groove to be the ball circulating passage as by concaving a groove on a part of the cylindrical first inner circumferential surface of the nut; and
integrally forming an outer circumferential formation on an outer circumferential surface of the nut within a range in an axial direction where the concaved groove is formed, whereinthe concaved groove is formed on the first inner circumferential surface of a cylindrical nut blank by pressing the first inner circumferential surface of the nut blank with a convex, by a press method using a die which includes a cam mechanism, the cam mechanism comprising a cam driver internally inserted into the nut blank and moving in the axial direction, a cam slider disposed between the nut blank and the cam driver, and having the convex corresponding to the concaved groove, the convex moving in a radial direction of the nut with a movement of the cam driver, and a restraining member for restraining both end faces in the axial direction and the outer circumferential surface of the nut blank, and having a first recess on a second inner circumferential surface that receives the outer circumferential surface of the nut blank, andthe outer circumferential formation is formed by projecting a periphery of the nut blank into the first recess of the restraining member.
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Accused Products
Abstract
A ball screw is provided in which an outer circumferential formation is formed at a portion facing a ball circulating passage out of outer circumferential surface of a nut. The ball screw includes: a screw shaft having on its outer circumferential surface a screw groove; a nut having on its inner circumferential surface a screw groove facing the screw groove; a plurality of balls rollably loaded in a spiral ball rolling passage formed by both screw grooves; and a ball circulating passage to return the balls from a start point to an end point of the ball rolling passage for recirculation. The ball circulating passage is a concaved groove formed by concaving a groove on a part of the cylindrical inner circumferential surface of the nut by plastic working. Then, a flange is integrally provided at a portion facing the ball circulating passage and the screw groove.
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Citations
7 Claims
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1. A manufacturing method of a ball screw, the ball screw including a screw shaft having on an outer circumferential surface a spiral screw groove, a nut having on its first inner circumferential surface a screw groove facing the screw groove of the screw shaft, a plurality of balls rollably loaded in a spiral ball rolling passage formed by the both screw grooves, and a ball circulating passage to return the balls from an end point to a start point of the ball rolling passage for circulating the balls, the manufacturing method comprising:
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forming a concaved groove to be the ball circulating passage as by concaving a groove on a part of the cylindrical first inner circumferential surface of the nut; and integrally forming an outer circumferential formation on an outer circumferential surface of the nut within a range in an axial direction where the concaved groove is formed, wherein the concaved groove is formed on the first inner circumferential surface of a cylindrical nut blank by pressing the first inner circumferential surface of the nut blank with a convex, by a press method using a die which includes a cam mechanism, the cam mechanism comprising a cam driver internally inserted into the nut blank and moving in the axial direction, a cam slider disposed between the nut blank and the cam driver, and having the convex corresponding to the concaved groove, the convex moving in a radial direction of the nut with a movement of the cam driver, and a restraining member for restraining both end faces in the axial direction and the outer circumferential surface of the nut blank, and having a first recess on a second inner circumferential surface that receives the outer circumferential surface of the nut blank, and the outer circumferential formation is formed by projecting a periphery of the nut blank into the first recess of the restraining member. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A die comprising,
a cam mechanism, the cam mechanism including: -
a cam driver internally inserted into a cylindrical nut blank and moving in an axial direction; a cam slider disposed between the nut blank and the cam driver, and having the convex corresponding to a concaved groove to be formed on a first cylindrical inner circumferential surface of the nut blank, the convex moving in a radial direction of the nut with a movement of the cam driver; and a restraining member for restraining both end faces in the axial direction and a outer circumferential surface of the nut blank, and having a recess on a second inner circumferential surface that receives the outer circumferential surface of the nut blank.
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Specification