Nitrogen die cylinder

Claim 1

In combination a die having a vertically movable member and a plate spaced vertically therefrom, a piston-cylinder assembly extending between said plate and said movable die member, said assembly comprising a vertically extending post having a threaded boss at one end thereof, said plate having a threaded port in which said boss is threaded to mount the post on said plate, a cylindrical sleeve having an axial bore closed by an end wall at one end and open at its opposite end, the open end of the sleeve being telescoped over the free end of the post so that the sleeve is vertically slideable on the post, said post having an axially extending cavity therein which is open at the free end of the post, said boss having an axial passageway therethrough communicating with said cavity, means connecting said passageway with a source of nitrogen at high pressure, said post having a bushing mounted adjacent its free end and slideably engaging said bore, said post also having mounted adjacent the free end thereof an annular seal in sealing engagement with said bore and the outer periphery of said post, said cavity communicating at the free end of the post with the portion of said bore extending between the closed end of the sleeve and said seal and being out of communication with the portion of said bore extending beyond said seal toward the open end of the sleeve so that the closed end of the sleeve is biased axially into force engagement with said movable die member when said cavity is pressurized from said source, said sleeve having a bushing mounted thereon adjacent its open end which slideably engages the outer periphery of the post, means adjacent the free end of the post forming an annular shoulder adapted to be axially abutted by said last-mentioned bushing to limit the extent of movement of the sleeve in a direction away from said plate, the closed end of the sleeve having a threaded hole therethrough at the vertical central portion thereof, a plug threaded into said hole and sealed therein, the free end of said post having means thereon axially aligned with said threaded hole and adapted to be engaged by a turning tool inserted through said threaded hole when the plug is removed to rotate the post and thereby enable the boss to be threaded into and out of engagement with said threaded port.