PURPOSE: To prevent dust from being generated, by arranging a lid member provided therein with a female thread part adapted to be threadrically engaged, with a certain clearance, to and disengaged from a part where a ball screw shaft is projected from a movable member, with a space between itself and the movable member, and by communicating a vacuum suction pipe to the space.
CONSTITUTION: A lid 12b is provided in a part where a ball screw shaft 1 threadrically engaged in a movable member 10 is projected from the latter, with a low pressure chamber as a space being disposed between the movable member 10 and the lid 12b. Further, the lid 12b is formed therein with a female thread part adapted to be threadrically engaged with the screw shaft 1 with a fine clearance therebetween, and a vacuum suction pipe 13 is disposed in the low pressure chamber 29b. Accordingly, it is possible to completely prevent dust from being produced from the ball screw shaft section to the outside.
TAKAMI KATSUMI
IMAI TOSHIHIKO
OTANI SEIJI
MORI AKIRA
