Method and apparatus for producing hollow articles

Claim 1

APPARATUS FOR EXPANDING A TUBULAR METAL WORKPIECE WITHIN A DIE HAVING THEREIN A CAVITY CONFORMING TO THE SHAPE TO WHICH SAID WORKPIECE IS TO BE EXPANDED AND ADAPTED TO RECEIVE SAID WORKPIECE, SAID APPARATUS COMPRISING MEANS FOR FILLING SAID WORKPIECE WITH HYDRAULIC FLUID WHEN IT IS SEATED IN SAID DIE AND FOR SEALING THE FLUID THEREIN, SAID MEANS INCLUDING AT LEAST ONE NOZZLE ADAPTED FOR SEALING ENGAGEMENT WITH AN ENDWISE PORTION OF SAID WORKPIECE, A POWER CYLINDER FOR OPERATING SAID NOZZLE, SAID NOZZLE HAVING A DUCTWAY COMMUNICATING WITH THE INTERIOR OF SAID WORKPIECE AND BEING EFFECTIVE WHEN MOVED BY SAID POWER CYLINDER TO PUSH SAID WORKPIECE INTO SAID DIE WHILE PRESSURE IS BEING APPLIED TO THE INTERIOR OF SAID WORKPIECE THROUGH SAID DUCTWAY, A SOURCE OF PRESSURE FLUID AT A PRESSURE SUBSTANTIALLY GREATER THAN THE YIELD POINT PRESSURE OF SAID WORKPIECE, FIRST PRESSURE CONTROL MEANS IN CONNECTION WITH SAID SOURCE FOR EXERTING AND MAINTAINING IN SAID WORKPIECE THROUGH SAID DUCTWAY A PRESSURE SUFFICIENT TO OVERCOME THE INITIAL YIELD POINT PRESSURE OF SAID WORKPIECE BUT INSUFFICIENT TO SUBSTANTIALLY BULGE THE WORKPIECE, SECOND CONTROL MEANS IN CONNECTION WITH SAID SOURCE OF PRESSURE AND OPERABLE WHILE SAID PRESSURE IS BEING MAINTAINED IN SAID WORKPIECE FOR APPLYING TO SAID POWER CYLINDER A PRESSURE SUFFICIENTLY HIGH TO MOVE SAID NOZZLE AND THEREBY FORCE SAID WORKPIECE ENDWISELY INTO SAID CAVITY, WHEREBY SAID WORKPIECE ASSUMES SUBSTANTIALLY THE CONTOUR OF SAID DIE CAVITY AS A CONSEQUENCE OF BEING FED INTO THE SAME, AND MEANS INCLUDING A CONTROL ELEMENT RESPONSIVE TO THE MOVEMENT OF THE NOZZLE FOR DECOMMISSIONING SAID FIRST PRESSURE CONTROL MEANS AND CAUSING A PRESSURE TO BE APPLIED TO THE INTERIOR OF SAID WORKPIECE FROM SAID PRESSURE SOURCE SUFFICIENTLY HIGH TO COIN THE SAID WORKPIECE AGAINST THE SURFACES OF SAID DIE AFTER SAID NOZZLE HAS FED THE WORKPIECE INTO SAID DIE.