Nsk Corporation

Kazuya Yamada

Kaname Yasuda

Yasuaki Abe

Tatsuya Suehiro

Kanta Sato

Yuji Shimomura

Motoshi Sakai

In the ball screw device, the circulation path that returns balls from the end point to the start point of the load path includes a return path, scooping paths, and connecting paths. The scooping path has an arc-shaped center line that is curved outward in the radial direction as going toward the reference imaginary flat plane including the center axis of the screw shaft and the center line of the return path in the circumferential direction. The connecting path is arranged on the reference imaginary flat plane and includes a straight path having a linear center line extending in a direction orthogonal to the center axis of the screw shaft. When the radius of curvature of the center line of the scooping path is R, the scooping angle is &#x3b8;, and the entire length of the straight path is S, Rcos(90&#xb0;&#x2212;&#x3b8;)+S is made larger than the diameter of the balls.

Ball screw device

A ball screw device has a screw shaft; a nut; a circulation part; and balls; a housing concave groove provided on the outer circumferential surface of the nut and linearly extending in the axial direction and opening to end surfaces on both outer sides in the axial direction of the nut, a circulation part arranged inside the housing concave groove, and the circulation part being prevented from displacing toward the outer side in the radial direction and displacing in the circumferential direction with respect to the nut by engaging an engaging convex portion of a fixing portion provided in the end portion on each of both outer sides in the axial direction of the circulation part with an engaging recess portion provided in the end portion of each of both outer sides in the axial direction of the housing concave groove.

To provide a method of manufacturing a shaft for a steering device, the shaft including a spline shaft part to be coupled with an input shaft, a stopper part to be coupled with an output shaft, and an intermediate shaft part that couples the spline shaft part with the stopper part. The method includes: a step of forming a hole part recessed in an axial direction from one end of a pillar-shaped material by forging; and a step of pressing the material in which the hole part has been formed into a die to perform drawing in a radial direction on a portion of the material at which the spline shaft part and the intermediate shaft part are formed, and prolonging a length along the axial direction of the hole part at the same time by forging.

Shaft for steering device, method of manufacturing shaft for steering device, and electric power steering device

A ball screw device includes: a screw shaft the outer peripheral surface of which has a first thread groove; a nut the inner peripheral surface of which is provided with a second thread groove that matches the first thread groove, and the outer peripheral surface of which is provided with a through hole; a plurality of balls that roll between the first thread groove and the second thread groove; a circulation component including a main body part and a pair of leg parts provided on both ends of the main body part, and that is provided on the nut; and a pin component that fixes the circulation component to the nut. Each of the leg parts is inserted into the through hole, the pin component is provided on the leg part in an overlapping manner, and the leg part is retained in the through hole by the pin component.

A shaft for a steering device has a first portion, a second portion, and a third portion that is a shaft integrated with the first portion and the second portion and couples the first portion and the second portion in a first direction. The outer diameter of the third portion is smaller than the length of the second portion in a second direction intersecting with the first direction, and is constant across a direction extending along the first direction. The hardness of the third portion is greater than the hardness of the second portion, and is constant across the direction extending along the first direction.

To provide a method of manufacturing a shaft for a steering device, the shaft including a spline shaft part to be coupled with an input shaft, a stopper part to be coupled with an output shaft, and an intermediate shaft part that couples the spline shaft part with the stopper part. The method includes: a step of forming a hole part recessed in an axial direction from one end of a pillar-shaped material by forging; and a step of pressing the material in which the hole part has been formed into a die to perform drawing in a radial direction on a portion of the material at which the stopper part is formed and prolonging a length along the axial direction of the hole part at the same time by forging.

Growing community of inventors

Gunma, Japan

Kazuya Yamada