Continuous machine for corrugating thermoplastic sheets

Claim 1

IN A MACHINE FOR CONTINUOUSLY CORRUGATING A WEB OF A SYNTHETIC THERMOPLASTIC MATERIAL, THE MACHINE BEING OF THE TYPE INCLUDING A PRELIMINARY HOT-DRAWING SECTION FOR LONGITUDINALLY DRAWING THE WEB INCLUDING A PAIR OF DRAWING ROLLS; A CORRUGATING SECTION FED BY SAID DRAWING ROLLS AND INCLUDING TWO TRANSVERSE SERIES OF HOLLOW, INTERNALLY COOLED SHAPING DIES ARRANGED TO ACT ON THE OPPOSITE FACES OF THE WEB TO TRANSVERSELY DRAW AND CORRUGATE THE LATTER THEREBETWEEN, ONE OF SAID SERIES OF DIES BEING DISPLACEABLE TOWARDS AND AWAY OF THE OTHER SERIES OF DIES; TAKE-OFF MEANS FOR PULLING THE WEB AT A PREDETERMINED SPEED THROUGH THE CORRUGATING SECTION IN SLIDING CONTACT WITH THE DIES IN THE TWO SERIES; AND MEANS CORRELATING THE PULL SPEED OF SAID TAKE-OFF MEANS AND THE EFFECTIVE SPEED OF THE DRAWING ROLLS; THE IMPROVEMENTS IN SAID CORRUGATING SECTION FOR PRODUCING CORRUGATED PROFILE UNDERCUTS COMPRISING; AT LEAST ONE UNDERCUT-SHAPING DIE IN ONE OF SAID SERIES HAVING ASSOCIATED THEREWITH A COMPLEMENTARY UNDERCUT-SHAPING DIE IN THE OTHER SERIES; MEANS FOR MUTUALLY DISPLACING THE UNDERCUT-SHAPING DIES RELATIVE TO ONE ANOTHER BETWEEN A NON-INTERLOCKED CONDITION, IN WHICH THE SAID ONE SERIES OF DIES ARE FREELY DISPLACEABLE AND AWAY FROM EACH OTHER SERIES, AND A MUTUALLY INTERLOCKED CONDITION IN WHICH THE UNDERCUT-SHAPING DIE OF ONE SERIES IS HOOKED BEHIND A COMPLEMENTARY DIE IN THE OTHER SERIES TO DETERMINE THE DESIRED UNDERCUT; ALL OF THE SHAPING DIES IN THE TWO SERIES BEING ARRANGED TO ESTABLISH WITH THE WEB AN OVERALL TRANSVERSE CONTACT DIMENSION SMALLER THAN THE AMOUNT OF THE TRANSVERSE DRAWING IN THE CORRUGATING SECTION; AND MEANS ADJACENT THE OPPOSITE ENDS OF THE SERIES OF DIES ARRANGED TO HOLD THE WEB TRANSVERSELY DURING OPERATION OF THE TWO SERIES OF DIES.