Die clamping apparatus

A die clamping apparatus comprising:

• a fixed die plate immovably fixed in the apparatus, said fixed die plate having a mounting surface for supporting a fixed die;
• a movable die plate movably supported in the apparatus, said movable die plate having a mounting surface for supporting a movable die opposite to the fixed die, and
• moving means operatively connected to said movable die plate for causing said movable die plate to advance toward said fixed die plate and close said dies and for causing said movable die plate to retreat from said fixed die plate and open said dies;
• tie bars fixedly secured to one of said die plates and immovable relative to said one of said die plates,
• said tie bars each including a first end from which the tie bars extend from said one of said die plates toward the other of said die plates, a tip end opposite said first end, and one of a thread and a series of grooves extending along the outer circumferential surface of said tip end;
• hydraulic cylinders disposed on the other of said die plates across from said tie bars, respectively,
• each of said hydraulic cylinders including a ram having an insert hole extending therethrough in an axial direction aligned with a respective one of said tie bars, the tip end of each of said tie bars extending through a respective said insert hole when said dies are closed,
• each said ram being movable in a direction parallel to said axial direction;
• a respective coupling means operatively associated with each of said tie bars, supported by said other of said die plates and movable relative thereto in directions parallel to said axial direction, and positioned adjacent a surface of said other of said die plates opposite the mounting surface thereof,
• each said coupling means having a peripheral surface that is complimentary to said one of said thread and series of grooves extending along the tip end of a respective one of said tie bars, and
• said peripheral surface movable, in directions perpendicular to said axial direction, into and out of mating engagement with said one of said threads and series of grooves of said respective one of said tie bars when said dies are closed so as to couple said die plates through said tie bars;
• means for causing said coupling means to move in said axial direction with said ram;
• and
• stopper means operatively connected to each said coupling means for adjustably setting a relative position, in said axial direction, of said coupling means and the tip ends of said tie bars with respect to when said dies are closed.