PURPOSE: To prevent deflection, vibration, etc. of a feed bar by extending a beam to a carriage moving on a rail being in parallel to the feed bar, and providing a lifting member on a truck moving on its beam.

CONSTITUTION: A guide rail 2 is provided in parallel to the outside of the end part of a feed bar 1. A beam 5 is extended through a carriage 4 which is freely movable on the rail 2 by a guide wheel 3, and a guide rail 6 is provided in parallel to both its end parts. A grasping truck 8 is made freely movable on the rail through guide wheels 9, 10, a guide post 7 is set on the truck 8, and a lifting sleeve 11 connected to the bar 1 is made freely movable upward and downward. According to this mechanism, the feed bar 1 moves freely upward and downward, also in the direction Y by the truck 8, and the carriage 4 can move in the direction X, and even if the feed bar 1 moves in the three-dimensional direction, said carriage follows its movement smoothly and exactly, and deflection, etc. of the end part of the bar 1 is prevented.