Device for adjusting the opening travel of the movable plate of a molding machine for plastic materials

A device for adjusting the opening travel of a mould holder unit of a machine for moulding plastic materials, comprising:

• a movable plate which is arranged to support a portion of the mould, said plate being movable, during the opening travel, from a first position, in which said mould is closed, to a second position in which said mould is opened;
• a cylinder comprising a piston movable in a casing and apt to actuate said movable plate;
• a stop member mounted in said casing to act as a stop for said piston during said opening travel, the position of the stop member being variable by displacing the stop member axially with respect to the casing;
• a threaded stem mounted to rotate within the casing and fixed against axial movement with respect to said casing;
• a screw nut connected to said stop member and in threaded engagement with the stem;
• means arranged to prevent said screw nut from rotating with respect to said casing, so that in consequence of the rotation of said threaded stem only axial translation of said screw nut, and said stop member connected thereto, takes place;
• supporting and sealing means for said stop member, said supporting and sealing means including a tubular element which is provided with seats for supporting said stop member and with sealing elements for preventing said fluid from penetrating between said movable member and said tubular element;
• and
• said casing of the cylinder including an end wall, and said threaded stem and said tubular element are provided with an annular end protuberance, the casing having formed therein a cavity in which the annular protuberance of said threaded stem is rotatable and a cavity in which the annular protuberance of said tubular element is fixed.