Ball screw mechanism and assembling method of the same

An assembling method of a ball screw mechanism which comprises:

• a screw shaft provided with a male screw groove on an outer circumferential surface thereof;
• a nut disposed so as to surround the screw shaft and provided with a female screw groove on an inner circumferential surface thereof;
• a plurality of balls disposed so as to freely roll along a rolling path formed between both the opposing screw grooves;
• and
• a holding member:
• wherein one of the screw shaft and the nut comprises a circulating portion connected to the screw groove of said one of the screw shaft and the nut to circulate the balls from one end to the other end of the rolling path,
• wherein the holding member is provided adjacent to the circulating portion to hold the balls,
• wherein the screw groove of said one of the screw shaft and the nut extends, from the one end to the other end of the rolling path, within a range of not more than 360 degrees round an axis of the screw shaft or the nut, and a sectional shape thereof taken at right angles to the screw groove includes a circular are portion of 90 degrees or less and a connecting portion which connects to the circular arc portion at a bottom of the screw groove, and
• wherein the connecting portion extends from the bottom of the screw groove toward an axial end of the ball screw mechanism such that, when observed in an axial view, the connecting portion does not overlap the circular arc portion,
• the assembling method comprising:
• inserting the screw shaft into an interior of the nut;
• and
• mounting the holding member after the balls are loaded in the circulating portion and the rolling path which connects to the circulating portion.

An assembling method of a ball screw mechanism which comprises:

• a screw shaft provided with a male screw groove on an outer circumferential surface thereof;
• a nut disposed so as to surround the screw shaft and provided with a female screw groove on an inner circumferential surface thereof;
• a plurality of balls disposed so as to freely roll along a rolling path formed between both the opposing screw grooves;
• and
• a holding member;
• wherein one of the screw shaft and the nut comprises a circulating portion connected to the screw groove of said one of the screw shaft and the nut to circulate the balls from one end to the other end of the rolling path,
• wherein the holding member is provided adjacent to the circulating portion to hold the balls
• wherein the screw groove of said one of the screw shaft and the nut extends, from the one end to the other end of the rolling path, within a range of not more than 360 degrees round an axis of the screw shaft or the nut, and a sectional shape thereof taken at right angles to the screw groove includes a circular arc portion of 90 degrees or less and a connecting portion which connects to the circular arc portion at a bottom of the screw groove, and
• wherein the connecting portion extends from the bottom of the screw groove toward an axial end of the ball screw mechanism such that, when observed in an axial view, the connecting portion does not overlap the circular arc portion,
• the assembling method comprising:
• inserting a temporary shaft into an interior of the nut,
• mounting the holding member after the balls are loaded in the circulating portion and the rolling path which connects to the circulating portion,
• the screw shaft is connected to the temporary shaft, and
• after the screw shaft is drawn into the interior of the nut while the temporary shaft and the screw shaft are being rotated, the temporary shaft and the screw shaft are disconnected from each other.