Nsk Corporation

Nsk Precision Co., Ltd.

Hiroki Yamaguchi

Ryoichi Sato

Shinichi Kasuga

Soichiro Kato

Nobumitsu Takahashi

Yoshinori Mizumura

Tsutomu Ohkubo

Kazuo Miyaguchi

Takeshi Nakazawa

Shirouji Yabe

Ryouichi Sato

Toshiaki Yamaguchi

Shiroji Yabe

Nobuaki Fujimura

Kenji Kano

Toru Tsukada

Toshikazu Yabe

Hirotoshi Aramaki

Tatsunobu Momono

Nobuhide Kurachi

Juntaro Sahara

Kenta Nakano

In a linear guide device, a rolling element cageholding balls interposed between a rail side rolling element rolling groove and a slider side rolling element rolling groove is formed of a synthetic resin material, and has two plate partsfacing to each other with a slider body being held therebetween. The rolling element cagehas a positioning part that makes contact with the inside surface of the slider body and is positioned on the slider body by the positioning part with respect to the slider.

Linear guide device

A linear guiding device where noise characteristics are improved by reducing traveling noise and operability of a slider body is smoothed, and where movement braking can be improved by reducing rolling body passage vibration. Crowningwith a curved surface having a predetermined curvature radius R is provided on an end section of a rolling body raceway grooveof a bearing block. A crowning amount C of the crowningis set to a value C&#x3e;Hgreater that the value of a maximum elastic deformation amount Hof a rolling body B elastically deformed in a rolling body rolling pathby a preload or an external load. By this, even when a large load acts on a bearing blockA or a large installation error occurs by skewing etc., the rolling body B smoothly rolls without an elastic deformation amount of the rolling body B rolling on the end section side of the rolling body raceway groovebecoming greater than the crowning amount C. As a consequence, significant worsening of a noise level and impairment of operability can be prevented.

Linear motion guiding apparatus

A spacer between adjacent balls of, for example, a ball screw device or a linear motion device has an outer periphery that is concave such that the spacer is elastically deformed to be in substantially circular line contact with the adjacent balls and that a distance therebetween is variable.

Ball screw device and linear motion device

Operability, low noise characteristic and endurance are further improved at a reduced cost and easily by suppressing the fluctuation of a pitch between rolling elements due to the effects of swelling caused by oil and fats such as lubricants also in a case of using the elastomer for the material of the retaining piece. In a linear guide device in which a retaining piecemade of an elastomeric material is interposed between each of steel balls B adjacent with each other in the circulating direction, the concaved surfaceof the retaining pieceis in contact with the steel ball B adjacent with the retaining pieceat a position for 50% or less of the diameter of the steel ball B, and the rigidity value of the retaining pieceis defined at 0.053 N/&#x3bc;m or more and 0.175 N/&#x3bc;m or less.

Direct drive unit

In a linear guide bearing apparatus wherein a separator is interposed between adjacent balls K and K moving following a curved circulating path, and the ball K contacts concave faces W of the separator Tat both ends in an axial line direction and at the same time the ball K rolls as contacting a guide faceof an outside guiding memberand a guide faceof an inside guiding member, the separator has an outer diameter larger than a maximum outer diameter L&#xd8; under a condition where the ball rolls as simultaneously contacting both curved facesof the inside and the outside of the curved circulating path, and the radius of curvature of the guiding facein the curved circulating pathis reduced to a size not contacting the separator T.

Linear guide bearing apparatus

A linear-motion device has: a linear-motion element fitted on a shaft which moves straight along the shaft; a plurality of balls which are retained in a ball groove formed on the inner side of the linear-motion element and roll over between the ball groove and the shaft; a separator interposed between the balls; and, a circulating path formed in the linear-motion element through which the balls are circulated from one end of the ball groove to the other, which is filled with a grease, wherein the separator is a formed product comprising as a resin component a polybutylene naphthalate-based elastomer formed by a hard segment made of a polybutylene naphthalate and a soft segment made of a polycondensate of 2,6-naphthalanedicarboxylic acid with a polytetramethylene ether glycol.

Linear-motion device and ball screw

In a linear guide bearing apparatus wherein a separator is interposed between adjacent balls K and K moving following a curved circulating path, and the ball K contacts concave faces W of the separator T at both ends in an axial line direction and at the same time the ball K rolls as contacting a guide faceof an outside guiding memberand a guide faceof an inside guiding member, the separator has an outer diameter larger than a maximum outer diameter L&#x3c6; under a condition where the ball rolls as simultaneously contacting both curved facesof the inside and the outside of the curved circulating path, and the radius of curvature of the guiding facein the curved circulating pathis reduced to a size not contacting the separator T.

Disclosed is a linear guide device in which a rate of change expressed as 'Dmax&#x2212;Dmin', becomes extremely small where Dmax and Dmin are respectively a local maximum and a local minimum of D, expressed as (dxdx)/dx, which is produced when a steel ball B moves a distance corresponding to a rolling element-to-rolling element span, dxis a minute movement quantity of a steel ball B when it moves from one space defined between rolling element rolling groovesandof an element endless circulating racewayto one of curved element circulating R partsand dxis a minute movement quantity of another steel ball B when it moves from the other curved element circulating R partto the space while the former steel ball is moved by the minute movement quantity dx

In a retaining piece interposed between the adjacent rolling balls, a concave surface of each of both side surfaces of the retaining piece where it contacts with the spherical surfaces of the balls is configured to partly contact with the spherical surface of the ball. The concave surface includes a linear contact portion to be in contact with the ball and an approximate curved surface having the radius of curvature approximate to that of the ball, which is located on the inner side of the linear contact portion. In addition, recesses which are joined to the gate portion and the ejector pin in a molding process are formed in the concave surfaces. A recess is formed at the joining portion or near a parting line. Fins formed in the molding process are capable to be put into the recess.

Retaining piece structure

In a ball screw device comprising a screw shaft and a nut which make relative movement to each other through a multiplicity of balls, as well as in a linear motion device comprising an outer member and an inner member which make the relative movements to each other through the multiplicity of balls, a spacer having two concave surfaces facing respectively to balls, is disposed between the balls adjacent to each other. A section of each of the concave surfaces of the spacer is formed of two circular arcs of which central positions deviate from each other to form a Gothic arch. The spacer has such a configuration that the balls adjacent to each other come into contact with outer edges thereof or portions vicinal to the outer edges. The spacer also has such a configuration that the balls adjacent to each other come into contact with at least three or more outer edge portions thereof or portions vicinal to the outer edges. The spacer may have a through-hole formed in a thinnest portion thereof.

A rolling element series is formed with a plurality of spherical rolling elements and four kinds of retainer pieces. The element-to-element thicknesses TA, TB, TC, and TD of the retainer pieces are different: T >T >T >T .

Linear motion guide bearing device and ball screw device

In the present linear guide bearing, the center of curvature O&prime; of a ball reversing passage is shifted to a return side ball passage side by a given amount m when compared with the center of curvature O&prime; of a conventional guide bearing. Due to this, not only the radius of curvature of a concave-arc-shaped groove formed in each end cap is reduced by a given amount m but also the concave-arc-shaped groove is shifted to the return side ball passage side by a given amount m, when compared with the conventional guide bearing. Thus, an angle &agr; formed between a line connecting the leading end of a tongue portion to the center of curvature O&prime; of a ball reversing passage and the moving-direction end face of a bearing main body can be reduced significantly when compared with the conventional bearing.

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Gunma, Japan

Hiroki Yamaguchi