| 摘要 |
Provided is an inexpensive, highly reliable bridge-type ball screw in which the step of a ball transfer part is eliminated and smoothed out to prevent abnormal sounds, and durability is improved. A method for manufacturing a bridge-type ball screw 1 provided with a bridge member 5 which is fitted into a bridge window 6 formed in the body of a nut 3, the bridge member 5 having a linking groove 5a that has a rolling track as a circuital path in the inner periphery, wherein: after the bridge member 5 is fitted into the bridge window 6 of the nut 3, a columnar mandrel 8 having a projection 9 is inserted into the nut 3; with the mandrel 8 supported while horizontal, an upper die 10 arranged radially outward from the nut 3 is lowered, the upper die 10 restraining the upper surface of the bridge member 5; the upper die 10 is lowered while the nut 3 is held between the upper die 10 and the mandrel 8; a connecting part between the linking groove 5a of the bridge member 5 and a thread groove 3a of the nut 3 is subjected to plastic working by the projection 9 of the mandrel 8; the outer-peripheral part of the bridge member 5 is simultaneously plastically deformed by the upper die 10; and the bridge member 5 is secured by caulking in the bridge window 6 of the nut 3. |
