Apparatus for supplying printing ink to a printing unit

Claim 1

Apparatus for delivering printing ink from a tubular cannister filled with said ink to a printing unit which comprises an elongated casing, there being means in said casing intermediate the ends thereof for dividing the interior of said casing into first and second axially disposed compartments, a capping plate, said capping plate being removably connected to one end of said casing whereby an ink filled tubular cannister can be insertably received coaxially within one of said compartments and removed therefrom when empty, ink conveyance conduit means extending from said capping plate to said printing unit and communicatively connecting said one compartment with said printing unit, a plunger disposed in said one compartment of said casing for sliding travel between a first operative position wherein said plunger is disposed in a position remote from said casing one end to a second operative position wherein said plunger is disposed in a position adjacent said one end and vice versa, said plunger during travel from said first to said second operative positions thereof moving through said cannister and forcing printing ink therefrom through said ink conveyance conduit means, means for stroking said plunger between its first and second operative positions at substantially constant rate of travel, said stroking means comprising a piston disposed in the other of said casing compartments for sliding travel therein, said piston having opposite side faces, said plunger being fixed to said piston for unitary travel therewith, said piston being movable between first and second operative positions corresponding to those of said plunger, said piston in its first operative position being disposed in a position adjacent the other end of said casing and in its second operative position remote from said casing other end, one of the side faces of said piston being in communication with the said other end of said casing, a source of compressed air, compressed air supply conduit means for communicating compressed air from said source to said one face of said piston, and a regulator for maintaining the pressure of the air flowing from said source through said compressed air supply conduit means at substantially constant level, and means for retracting said plunger from its second to first operative positions, said retracting means comprising second compressed air supply conduit means for communicating compressed air from said source to the other face of said piston.