BORING HEAD

A boring head of a multiple-operation machine tool comprises a housing which is kinematically coupled to a spindle and adapted to accommodate a carriage spring-biased against the housing, carrying a mandrel for a cutting tool and having a slanted surface to interact with a slanted surface of a rod arranged in the housing coaxially with the latter and kinematically coupled to a drive which moves it in the axial direction. The boring head also incorporates a counterbalance comprising at least a pair of pins received in through holes provided in the carriage. The holes are symmetrical with respect to the axis of rotation of the boring head and extend at a perpendicular to said axis of rotation. The pins are kinematically coupled to the rod so that they can reciprocate in the through holes of the carriage.