Ntn Corporation

Koji Tateishi

Yoshinori Ikeda

Isamu Yoshida

Morihisa Yoshioka

Kiyoshige Yamauchi

Keisuke Kazuno

Masaaki Toda

Takayuki Owada

Masahiro Nobutomo

Hirakazu Yoshida

Kiyohito Ishikawa

A ball screw has a nut formed with a helical ball rolling groove on its inner circumference. A screw shaft is formed with a helical ball rolling groove on its inner circumference. The screw shaft is inserted into the nut. A number of balls are rollably contained within a ball rolling passage formed by oppositely arranged helical ball rolling grooves of the nut and the screw shaft, respectively. The nut is made of case hardened steel. The ball rolling groove is formed by cutting and surface hardening, by vacuum carburizing hardening, without any after-processing.

Ball screw and a method for manufacturing the same

An electrically driven linear actuator has an actuator body with a ball screw to convert a rotational motion to a linear motion. An electric motor provides the rotational motion. A gear mechanism transmits rotational motion of the electric motor to the ball screw of the actuator body. A position holding mechanism holds the position of the ball screw of the actuator body by engaging teeth, specifically a space between adjacent teeth, of a gear forming the gear mechanism.

Electrically driven linear actuator

An electrically driven linear actuator () has an electric motor with a ball screw mechanism (and) connected to an output shaft () of the electric motor (), via a power transmitting mechanism (and) to convert a rotary motion of the electric motor () to a linear motion of an object member to be controlled by the actuator (). Housing members (and) contain the ball screw mechanism (and) and the power transmitting mechanism (and). Stroke end members (and), of a ball screw shaft () or a ball screw nut () forming the ball screw mechanism (and), are rotatably supported relative to the housing members (and) via a free rotation mechanism (and).

Electronically driven linear actuator

A ball screw shaft supporting structure of a ball screw rotationally supported by a housing via supporting bearings has a screw shaft formed, on its outer circumference, with a fitting portion and a positioning shoulder. An inner ring of the supporting bearing is press fit onto the fitting portion via a predetermined interference. A steel spacer ring is fit onto the fitting portion from the outer side of the supporting bearing with the inner side of the inner ring abutted against the shoulder. A caulking portion is formed on the end of the fitting portion by plastically deforming the end of the fitting portion radially outward. The inner ring is axially immovably secured on the screw shaft by the caulking portion via, the spacer ring.

Supporting structure of ball screw shaft

An electrically powered steering device comprises a ball screw mechanism for transmitting a steering force from a steering wheel to steerable vehicle wheels. The ball screw mechanism includes a rotary nut having a nut body in which a circulating passage is formed so as to extend axially thereof, and end caps and secured respectively to opposite ends of the nut body . Each of the end caps and has defined therein respective guideways and for balls that communicate opposite ends of the circulating tunnel with a ball rolling passage . The end caps and and the nut body are made of a sintered alloy. The nut body has an outer periphery of one end thereof that is axially progressively reduced in diameter to define a tapered surface.

Electrically powered steering device

A ball screw mechanism ( ) compact in size, employing a minimized number of component parts and having a high load capacity includes a rotary nut ( ) having an internally threaded helical groove ( ) and a mounting hole ( ) both defined therein, and a simplified bridge member ( ) mounted in the rotary nut ( ). The bridge member ( ) has a plurality of connecting grooves ( ) defined on an inner surface thereof each operable to communicate neighboring convolutions of the internally threaded helical groove ( ). The bridge member ( ) has its opposite side edges formed with respective guide walls ( ) protruding in a direction radially outwardly of the rotary nut ( ) that are crimped to allow the bridge member ( ) to be fixedly retained within the mounting hole ( ).

Ball screw mechanism and electrically powered steering device utilizing the same

An injection unit driving device or an mold-clamping unit driving device having a ball screw having a long life. Of the parts of the ball screw, only the balls are subjected to carburizing/nitriding treatment, while the threaded shaft and the nut are subjected to conventional hardening.

Growing community of inventors

Iwata, Japan

Koji Tateishi