Process of manufacturing sacks

Claim 1

A PROCESS OF MANUFACTURING BAGS WHICH ARE PRISMATIC WHEN FILLED, FROM A LENGTH OF FLAT PLASTIC TUBING FORMED BY TWO ELONGATED SUPERIMPOSED SHEETS HAVING FREE TRANSVERSE END EDGES AND BEING INTEGRALLY JOINED AT LONGITUDINAL EDGES THEREOF, SAID PROCESS COMPRISING THE STEPS OF INWARDLY FOLDING TRIANGULAR PORTIONS FROM SAID FLAT TUBING AT EACH CORNER THEREOF WHILE SIMULTANEOUSLY FOLDING AT OPPOSITE ENDS OF SAID TUBING A PORTION OF ONE SHEET ALONG A FIRST FOLD LINE PARALLEL TO THE RESPECTIVE END EDGE THEREOF AGAINST THE REMAINDER OF SAID ONE SHEET SO AS TO FORM AT EACH END OF SAID TUBING A PAIR OF TRIANGULAR POCKETS FACING WITH OPEN ENDS EACH OTHER AND RESPECTIVELY HAVING APICES AT OPPOSITE LONGITUDINAL EDGES OF SAID SHEETS AND BASES SUBSTANTIALLY PARALLEL TO SAID LONGITUDINAL EDGES; FOLDING THE FOLDED SHEET PORTIONS OF SAID ONE SHEET AND THE END PORTIONS OF THE OTHER SHEET ADJACENT THERETO RESPECTIVELY AGAINST EACH OTHER ALONG SECOND FOLD LINES PARALLEL TO SAID FIRST FOLD LINES AND CLOSER THERETO THAN TO THE CORRESPONDING FREE EDGE OF THE RESPECTIVE SHEET SO THAT THE FOLDED PORTIONS WILL OVERLAP EACH OTHER; INSERTING A WELD-PREVENTING SEPARATING MEANS OVER ONE OF THE TRIANGULAR PORTIONS OF EACH PAIR OF TRIANGULAR POCKETS AND BENEATH THE OVERLAPPING FOLDED PORTIONS INTO THE OTHER OF THE PAIR OF POCKETS; WELDING SAID OVERLAPPING SHEET PORTIONS TO EACH OTHER AND TO THE TRIANGULAR PORTION FORMING SAID OTHER POCKET; AND SUBSEQUENTLY WITHDRAWING SAID WELD-PREVENTING SEPARATING MEANS IN DIRECTION OF SAID FOLD LINES TO LEAVE BETWEEN SAID ONE TRIANGULAR PORTION AND SAID OVERLAPPING PORTIONS A FILLING OPENING FOR FILLING MATERIAL INTO THE BAG.