Abstract: The clamping comprises a tie-bar which extends between a fixed and a movable platen of a molding machine, with respect to the first, and hydraulically operated locking means for engaging the tie bar and generating the clamping force. The locking means comprises a hydraulic cylinder having a hollow sleeve and piston provided with internal toothings, in axially spaced apart positions. The sleeve and piston unit is made to rotate and slide axially, to selectively engage and disengage with the toothed head at the end of the tie bar to allow step and fine adjustments of the position of the movable platen, in relation to the thickness of the mold.

Abstract: A method and a mold clamping press for injection molding machines; the press comprises a stationary platen and a movable platen operatively connected to control means which can be operated to relatively move the platens towards and away from each other. Slidable tie-rods, each connected to a respective control cylinder, axially extend between the platens passing through locking bushes rotatably supported by a platen of the press. Each locking bush and the corresponding tie-rod are provided with opposite intermeshing screw threads having an axial clearance; the bushes are made to rotate in synchronism and in a way correlated to the displacement of the movable platen, avoiding any frictional contact between the screw threads during the closing and opening of the mold.