Apparatus and method for forming corrugated tubes

Claim 1

THE METHOD OF FORMING A TRANSVERSELY CORRUGATED TUBE HAVING A PLURALITY OF CORRUGATIONS ALONG ITS LENGTH WHICH COMPRISES, FEEDING THE TUBE FORWARD ON A RIGID STATIONARY MANDREL HAVING A CIRCUMFERENTIAL SEALS AT SPACED FIXED POINTS THEREALONG FOR ENGAGING THE INSIDE SURFACE OF THE TUBE AND WITH A CHANNEL AND OUTLETS FOR ADMITTING FLUID INTO THE TUBE BETWEEN THE SEALS; GRIPPING AND SUPPORTING THE TUBE ON SAID MANDREL CIRCUMFERENTIALLY EXTERIORLY THEREOF AND IMMEDIATELY ABOVE AND IN FRONT OF THE FORWARD SEAL BETWEEN SAID TUBE AND SAID MANDREL AND HOLDING IT FIXED AGAINST AXIAL MOVEMENT AT THIS POINT; EXTERIORLY SUPPORTING THE TUBE ON SAID MANDREL ABOVE AND BEHIND THE REARWARD SEAL BETWEEN SAID TUBE AND SAID MANDREL, THE AXIAL SPACE BETWEEN SAID SEALS BEING SUCH AS TO PROVIDE A SUFFICIENT LENGTH OF TUBE TO FORM A CORRUGATION AND THE TUBE BEING INITIALLY UNSUPPORTED EXTERIORLY BETWEEN SAID SEALS; APPLYING FLUID PRESSURE DIRECTLY WITHIN THE TUBE BETWEEN THE SPACED SEALS TO FORM AN INITIAL ANNULAR EXTERNAL BULGE BETWEEN THE SPACED POINTS OF EXTERNAL SUPPORT; HOLDING THE TUBE GRIPPED AT THE FORWARD INTERIOR SEAL; AND ENGAGING THE REARWARD END OF THE BULGE EXTERIORLY AND PUSHING THE REARWARD PORTION OF THE TUBE FORWARD PAST THE FIXED-POSITIONED REARWARD SEALING MEANS AND, AT THE SAME TIME, CONTINUING TO APPLY FLUID PRESSURE WITHIN THE TUBE BETWEEN THE SPACED SEALS TO INCREASE THE DIAMETER OF THE BULGE UNTIL A CORRUGATION IS FULLY FORMED; AND, WHEN ONE CORRUGATION IS THUS FORMED, RELEASING THE TUBE EXTERIORLY AT THE FORWARD SEAL, CONTINUING TO PUSH ON THE REARWARD SIDE OF THE FORMED CORRUGATION TO MOVE THE TUBE FORWARD TO CARRY THE FORMED CORRUGATION PAST THE FORWARD SEAL, AND REPEATING SAID OPERATIONS TO FORM ANOTHER CORRUGATION.

Claim 2

THE METHOD OF FORMING A TRANSVERSELY CORRUGATED TUBE HAVING A PLURALITY OF CORRUGATIONS ALONG ITS LENGTH WHICH COMPRISES, FEEDING THE TUBE FORWARD ON A RIGID STATIONARY MANDREL HAVING A CIRCUMFERENTIAL SEALS AT SPACED FIXED POINTS THEREALONG FOR ENGAGING THE INSIDE SURFACE OF THE TUBE AND WITH A CHANNEL AND OUTLETS FOR ADMITTING FLUID INTO THE TUBE BETWEEN THE SEALS; GRIPPING AND SUPPORTING THE TUBE ON SAID MANDREL CIRCUMFERENTIALLY EXTERIORLY THEREOF AND IMMEDIATELY ABOVE AND IN FRONT OF THE FORWARD SEAL BETWEEN SAID TUBE AND SAID MANDREL AND HOLDING IT FIXED AGAINST AXIAL MOVEMENT AT THIS POINT; EXTERIORLY SUPPORTING THE TUBE ON SAID MANDREL ABOVE AND BEHIND THE REARWARD SEAL BETWEEN SAID TUBE AND SAID MANDREL, THE AXIAL SPACE BETWEEN SAID SEALS BEING SUCH AS TO PROVIDE A SUFFICIENT LENGTH OF TUBE TO FORM A CORRUGATION AND THE TUBE BEING INITIALLY UNSUPPORTED EXTERIORLY BETWEEN SAID SEALS; APPLYING FLUID PRESSURE DIRECTLY WITHIN THE TUBE BETWEEN THE SPACED SEALS TO FORM AN INITIAL ANNULAR EXTERNAL BULGE BETWEEN THE SPACED POINTS OF EXTERNAL SUPPORT; HOLDING THE TUBE GRIPPED AT THE FORWARD INTERIOR SEAL; AND ENGAGING THE REARWARD END OF THE BULGE EXTERIORLY AND PUSHING THE REARWARD PORTION OF THE TUBE FORWARD PAST THE FIXED-POSITIONED REARWARD SEALING MEANS AND, AT THE SAME TIME, CONTINUING TO APPLY FLUID PRESSURE WITHIN THE TUBE BETWEEN THE SPACED SEALS TO INCREASE THE DIAMETER OF THE BULGE UNTIL A CORRUGATION IS FULLY FORMED; AND, WHEN ONE CORRUGATION IS THUS FORMED, RELEASING THE TUBE EXTERIORLY AT THE FORWARD SEAL, CONTINUING TO PUSH ON THE REARWARD SIDE OF THE FORMED CORRUGATION TO MOVE THE TUBE FORWARD TO CARRY THE FORMED CORRUGATION PAST THE FORWARD SEAL, AND REPEATING SAID OPERATIONS TO FORM ANOTHER CORRUGATION.