Method of forming articles and article forming apparatus

Claim 1

A SHEET FORMING PRESS COMPRISING A PAIR OF CONTINUOUS OPPOSED SHEET CLAMPING SURFACES, MEANS FOR DIRECTING A CLAMPING FORCE BETWEEN SAID SURFACES AND NORMAL TO THE PLANE OF THE SHEET TO BE FORMED, A FORMING DIE MEMBER HAVING A SIDE WALL NORMAL TO THE CLAMPING SURFACE AND SUBSTANTIALLY COEXTENSIVE THEREWITH, A PRE-FORMING PUNCH, SAID PRE-FORMING PUNCH HAVING A CROSS DIMENSION SUBSTANTIALLY LESS THAN THE CROSS DIMENSION OF THE FORMING DIE, A GENERALLY FLAT BASE AND A CONVEX SIDE WALL, MEANS FOR URGING SAID PRE-FORMING PUNCH INTO SAID FORMING DIE A DISTANCE GREATER THAN THE FINISHED DEPTH OF THE DEPRESSION TO BE FORMED IN THE SHEET, A FINAL FORMING PUNCH, SAID FINAL FORMING PUNCH FORMING A SLEEVE ABOUT THE PRE-FORMING PUNCH, THE CROSS DIMENSION OF THE OUTER SURFACE OF SAID FINAL PUNCH PROVIDING ONLY A WORKING TOLERANCE IN SAID FORMING DIE, AND MEANS FOR URGING SAID FINAL FORMING PUNCH INTO SAID DIE FOLLOWING PRE-FORMING BY SAID PRE-FORMING DIE.