Nsk Corporation

Takeshi Saito

A rolled thread screw includes: a screw part having, on an outer circumferential part of the screw part, thread crests and thread grooves disposed alternately along an axial direction of the rolled thread screw; and a columnar part adjoining at least one of both sides of the screw part in the axial direction. An axial end surface of the columnar part is provided with: a first concave surface concave in the axial direction; a second concave surface positioned to an outer circumference of the first concave surface and being concave in the axial direction; and a salient part positioned on a boundary between the first concave surface and the second concave surface and projecting further than a bottom of the first concave surface and a bottom of the second concave surface, the salient part extending in an arc-like shape along a circumferential direction of the columnar part as viewed in the axial direction.

Rolled thread screw and rolled thread screw manufacturing method

A screw shaft includes a large-diameter shaft portion having a male-side screw portion over the entire length of the outer circumferential surface thereof; a first small-diameter shaft portion arranged adjacent to one side in the axial direction of the large-diameter shaft portion, and having an outer diameter that is smaller than the outer diameter of the large-diameter shaft portion, and having a helical first rolling mark on the outer circumferential surface thereof; and a second small-diameter shaft portion arranged adjacent to the other side in the axial direction of the large-diameter shaft portion, and having an outer diameter that is smaller than the outer diameter of the large-diameter shaft portion, and having a helical first rolling mark on the outer circumferential surface thereof.

Screw shaft and method for manufacturing same, and electric position adjusting device for steering wheel and method for manufacturing same

Provided is a screw shaft in which shape accuracy of a male threaded portion is sufficiently secured. A screw shaft includes a large-diameter shaft portion, medium-diameter shaft portions and small-diameter shaft portions. The large-diameter shaft portion has a male threaded portion along its entire axial length on its outer peripheral surface. The medium-diameter shaft portions are arranged axially adjacent to the large-diameter shaft portion and have an outer diameter smaller than an outer diameter of the large-diameter shaft portion. The small-diameter shaft portions are axially arranged adjacent to the medium-diameter shaft portions on sides opposite to the large-diameter shaft portion, have an outer diameter smaller than the outer diameter of each of the medium-diameter shaft portions, and do not have rolling traces having a helical shape on their outer peripheral surfaces.

Screw shaft and method for producing same, and electric position-adjusting device for steering wheel

The nut according to the present invention includes: a cylindrical portion having a female screw portion provided with spiral shaped thread grooves on an inner circumferential surface thereof; and a slit provided at one location in a circumferential direction of the cylindrical portion and opening to an outer circumferential surface and an inner circumferential surface of the cylindrical portion. The slit extends in an extending direction orthogonal to a direction of a lead angle in a portion of the thread grooves crossed by the slit.

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Maebashi, Japan

Takeshi Saito