Compact clamp apparatus with integrated mold break

A clamp assembly for an injection molding machine, the clamp assembly comprising:

• a) a clamp cylinder housing having an inner end and an outer end spaced axially apart from the inner end;
• b) a clamp piston comprising a piston head affixed to an end portion of a tie bar, the clamp piston slidable within the housing;
• c) a clamp chamber axially intermediate the piston head and the inner end of the housing for urging the clamp piston from a meshing position towards the outer end of the housing when pressurized;
• d) a return device axially intermediate the piston head and the outer end of the housing, the return device accommodating movement of the clamp piston from the meshing position towards the outer end of the housing when the clamp chamber is pressurized, the return device having a return device engagement surface movable away from the outer end of the housing to an engagement surface advanced position for pushing the clamp piston back to the meshing position when pressure in the clamp chamber is relieved;
• and
• e) a mold break chamber within the housing for urging the clamp piston from the meshing position towards the inner end of the housing when pressurized.

A clamp assembly for an injection molding machine, the clamp assembly comprising:

• a) a clamp cylinder housing;
• b) a clamp piston affixed to an end portion of a tie bar and slidable within the housing among a clamping position, a mold break position, and a meshing position disposed axially intermediate the clamping and the mold break positions;
• c) a clamp chamber disposed within the housing for urging the clamp piston towards the clamping position when pressurized;
• d) a return device disposed within the housing for urging the clamp piston towards the meshing position when pressure in the clamp chamber is relieved;
• and
• e) a mold break chamber bounded axially by a tie bar mold break surface of the tie bar and a return device mold break surface of the return device, the mold break chamber for urging the clamp piston towards the mold break position when pressurized.

A method of operating a clamp assembly of an injection molding machine, the method comprising:

• a) relieving pressure in a mold break chamber, the mold break chamber for urging a piston assembly affixed to a tie bar from a meshing position towards an inner end of a clamp housing when pressurized to urge apart mold halves of the injection molding machine;
• b) pressurizing a clamp chamber to urge the piston assembly towards an outer end of the housing;
• and
• c) relieving pressure in the clamp chamber and moving a return device engagement surface of a return device away from the outer end of the housing and to an engagement surface advanced position, the return device engagement surface pushing the piston assembly to the meshing position during movement to the engagement surface advanced position.