Rolling-element screw device and method of assembling the same

A rolling-element screw device comprising:

• a screw shaft having an outer surface with a rolling-element rolling groove spirally formed thereon;
• a nut main body having an inner surface with a loaded rolling-element rolling groove spirally formed thereon facing the rolling-element rolling groove of the screw shaft;
• a plurality of rolling elements arranged between the rolling-element rolling groove of the screw shaft and the loaded rolling-element rolling groove of the nut main body;
• and
• a circulation member for, after each of the rolling elements rolls up to one end of the loaded rolling-element rolling groove of the nut main body, scooping up the rolling element and returning the rolling element to an opposite end of the loaded rolling-element rolling groove,
• the circulation member having a first pipe and a second pipe each having a scooping portion formed at one end thereof for scooping up each of the rolling elements and a direction change path extending in a curve,
• the first pipe being attached to one axial end surface of the nut main body, and
• the second pipe being attached to an axially opposite end surface of the nut main body.