Nsk Corporation

Akio Sakai

Masami Tanaka

Hiroyuki Ikeda

Takaji Iwasawa

Katsuyuki Yamamoto

Kazuo Miyaguchi

Daisaku Kawada

Masahito Sato

Goro Hirose

A grinding apparatus for grinding a spline ball groove on a workpiece comprises a rod-shaped grindstone, having a distal end portion with a curved surface corresponding to the groove to be ground, and a spindle mechanism for rotating the grindstone. The spindle mechanism and the grindstone are supported by means of a supporter in a manner such that they are inclined at a given angle to an axis of the workpiece. A rotary dresser, which has a dress groove corresponding to the curved surface of the distal end portion of the grindstones is disposed near the grinding apparatus. The grindstone can be reciprocated along the axis of the workpiece by a drive mechanism between the workpiece and the dresser without changing its angle of inclination.

Method and apparatus for forming grooves on a workpiece and for dressing a grindstone used in the groove formation

A grinding apparatus for grinding a spline ball groove on a workpiece comprises a rod-shaped grindstone, having a distal end portion with a curved surface corresponding to the groove to be ground, and a spindle mechanism for rotating the grindstone. The spindle mechanism and the grindstone are supported by means of a supporter in a manner such that they are inclined at a given angle to an axis of the workpiece. A rotary dresser, which has a dress groove corresponding to the curved surface of the distal end portion of the grindstone, is disposed near the grinding apparatus. The grindstone can be reciprocated along the axis of the workpiece by a drive mechanism between the workpiece and the dresser without changing its angle of inclination.

Method for forming grooves on workpiece and for dressing a grindstone used in the groove formation

Grinding apparatus for forming grooves on a workpiece and a method for dressing a grindstone used in the apparatus

An internal-circulation-type ball screw having simple construction and high productivity is provided. A ball nut has one or more through holes and one or more constrictions, which are formed around its outer peripheral surface so as to span the openings of respective through holes. One or more deflectors are put in respective through holes and fixed by fitting corresponding deflector-locking springs onto the constrictions. Each deflector-locking spring is a thin plate spring having a substantially C-shaped cross section with a concave portion in the middle. When the deflector-locking spring is fitted onto the constriction, the concave portion thereof presses the deflector in the through hole toward the threaded shaft. Thus, the deflector is fixed to the ball nut.

Internal-circulation-type ball screw device

An electric linear actuator includes an output shaft which is non-rotatable but displaceable in an axial direction and which has one end thereof coupled to a driven device; a cylindrical member arranged coaxially with the output shaft and rotatably about the output shaft, and driven by an electric motor for rotation; and a feed screw mechanism arranged between the output shaft and the cylindrical member for converting a rotating motion of the cylindrical member to a linear motion of the output shaft. The feed screw mechanism has a male spiral groove formed in the outer peripheral surface of the output shaft; a nut cylinder secured on the inner peripheral side of the cylindrical member and formed with a plurality of circular holes; and a plurality of balls accommodated in the circular holes and engaged with the male spiral groove.

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Maebashi, Japan

Akio Sakai