Apparatus for compensating for deviations in the straightness of the bed of a machine tool

Claim 1

In a machine tool having a longitudinally extending bed provided by at least one longitudinally extending way and a carriage movable along said bed and guided by said way, apparatus for compensating for deviations in the straightness of said way comprising a laser-type transmitter projecting a laser beam parallel to the longitudinal axis of the machine tool and the longitudinal extent of said way and providing a reference of straightness, a laser beam detector means movable with said carriage as it moves along said bed and arranged to receive said laser beam and to provide a signal indicative of deviations in the straightness of said bed from said reference of straightness, means on said carriage for carrying the working tool of said machine tool and for moving said tool laterally of said bed, control means receiving said signal from said detector and actuating said tool carrying means to move said tool in a direction and in an amount to compensate for the deviations in the straightness of the bed relative to said reference of straightness, said control means being mounted on said carriage and including a control member operatively connected to said tool carrying means and movable in accordance with said signal from said detector means to cause a compensating movement of said tool, means for movably mounting said detector means on said carriage and means movable by said control member for causing a movement of said detector means corresponding to the movement imparted to said tool so that said tool and said detector means are both given a corresponding movement, said tool carrying member comprising a cross-slide mounted on said carriage and adapted to provide a desired transverse movement to said tool in addition to said compensating movement by said control means, said cross-slide comprising a crossfeed screw for imparting transverse movement to said tool, said crossfeed screw extending transversely of said bed and being mounted for transverse movement, said control member being operatively connected to said crossfeed screw to impart a transverse movement thereto to achieve said compensating movement of said tool.