Nsk Corporation

Shingo Saitou

Koji Hashimoto

Tomofumi Yamashita

Toru Harada

Kazuto Kobayashi

Toshio Nakamura

Shinobu Mogi

Kiyoshi Ootsuka

Shouji Yokoyama

Atsushi Watanabe

Yoshinori Jingu

A method forms a concave constituting a ball return passage directly on an inner circumferential surface of a nut blank by plastic working without damaging a die. Letter S shaped concaves are formed on an inner circumferential surface of a nut blank, by pressing by use of a die having a blank holder, a cam driver, cam sliders, and a cylindrical member. The cam driver has inclined surfaces having the same angle of inclination as the cam sliders. The cam sliders have letter S shaped convexes corresponding to the letter S shaped concaves, and are held by through holes, respectively. When the cam driver is pressed from the top thereof, the cam sliders move outwardly in the radial direction, respectively, and the letter S shaped convexes push the inner circumferential surface of the nut blank for plastic deformation.

Method for manufacturing nut for ball screw and ball screw

Since it is configured that an female screw grooveof a nutextends round an axis of the nutthrough 360 degrees or less and a sectional shape thereof taken at right angles to the groove contains a circular arc portionof 90 degrees or less and a rectilinear portionwhich connects to the circular arc portion at a bottom of the groove and extends in parallel with the axis, after molding, a lower mold LM and an upper mold UM can simply be removed from a barrel mold BM in the axial direction, and consequently, the necessity of provision of a parting plane which passes through the thread groovecan be obviated, thereby making it possible to easily form the thread groovewhich is free from a difference in level or a stepped portion.

Ball screw mechanism and assembling method of the same

A ball screw apparatus of a screw shaft circulating-type includes a nut having a first groove formed in an inner peripheral surface thereof, a screw shaft having a second groove formed in an outer peripheral surface thereof, and a plurality of rolling elements provided between the first and second grooves. A circulating groove is formed in the screw shaft so as to interconnect opposite ends in a spiral direction of the second groove of the screw shaft to form a closed-loop ball endless circulating passageway. Processing relief portions for preventing a processing tool of a rotary drive-type from interfering with the circulating groove when processing the second groove of the screw shaft by the processing tool are provided respectively at the opposite end portions in the spiral direction of the second groove of the screw shaft.

Ball screw apparatus

Growing community of inventors

Fujisawa, Japan

Shingo Saitou