Method and apparatus for forming corrugated tubing

Claim 1

IN APPARATUS FOR CONTINUOUSLY FORMING A TUBE ABOUT A SELECTED AXIS BY HELICALLY WINDING THEREABOUT A STRIP OF SHEET METAL AND CORRUGATING SUCH TUBE, INCLUDING IN COMBINATION: A STRIP FEEDER HAVING OPPOSED FEED ROLL MEANS BETWEEN WHICH SUCH STRIP IS DIRECTED, SAID FEED ROLLS BEING POWER DRIVEN THEREBY FORCEFULLY FEEDING SAME; A TUBE FORMER FOR RECEIVING THE STRIP FROM SAID STRIP FEEDER, INCLUDING GUIDE MEANS FOR GUIDING SUCH STRIP IN A HELICAL PATH ABOUT SUCH AXIS INTO A TUBULAR CONFIGURATION HAVING THE EDGES OF THE STRIP POSITIONED ADJACENT ONE ANOTHER, SAID TUBE FORMER ALSO INCLUDING A WELDING MEANS FOR CONTINUOUSLY JOINING THE EDGES OF THE ONCOMING STRIP WITH THOSE OF THE TUBE, THE TUBE SO FORMED THUS BEING CAUSED TO ROTATE ABOUT SUCH AXIS AT A RATE PROPORTIONAL TO THE SPEED OF SUCH STRIP FEED, SAID TUBE FORMER INCLUDING A ROTATABLE CENTRAL ROLL, THE AXIS OF ROTATION OF WHICH EXTENDS IN THE SAME DIRECTION AS THE LONGITUDINAL AXIS OF SAID TUBE AND UPON THE UPPER SURFACES OF WHICH THE TUBE RESTS AS THE STRIP IS FORMED INTO SUCH TUBE AS AFOREMENTIONED; A CORRUGATING HEAD POSITIONED FOR CORRUGATIONS THE TUBE SO FORMED BY THE TUBE FORMER, SAID CORRUGATING HEAD INCLUDING AN INNER CORRUGATING SUB-HEAD MOUNTED FOR ROTATION WITHIN SUCH TUBE, AN OUTER ROTATABLY MOUNTED CORRUGATING SUBHEAD CONSTRUCTED AND ARRANGED FOR COOPERATING WITH SAID INNER SUB-HEAD FOR CORRUGATING SUCH TUBE, MEANS FOR ROTATING SAID SUB-HEADS IN A COMMON ANGULAR DIRECTION AT A COMMON ANGULAR SPEED WHEREBY THEY COOPERATE TO CORRUGATE SUCH TUBE, SAID CORRUGATING SUB-HEADS BEING MOUNTED FOR ROTATION ABOUT SUCH LONGITUDINAL AXIS OF THE TUBE; SAID STRIP FEEDER INCLUDING MEANS FOR FEEDING SAID STRIP TO SAID TUBE FORMER AT A SELECTED SPEED HAVING A PREDETERMINED RATIO WITH RESPECT TO THE SPEED OF ROTATION OF SAID CORRUGATING HEAD, SAID RATIO BEING A FUNCTION OF THE LEAD OF THE CORRUGATION OF THE TUBE AS COMPARED TO THE RATE OF FORMATION OF SUCH TUBE, TUBE BRAKING HEAD MEANS SITUATED INTERMEDIATE THE AFOREMENTIONED CORRUGATING HEAD AND TUBE FORMER AND INCLUDING INNER BACK-UP ROLL MEANS SITUATED WITHIN THE TUBE AND ENGAGING THE INNER SURFACE THEREOF, SAID BACK-UP ROLL MEANS BEING MOUNTED COAXIALLY WITH THE CORRUGATING HEAD FOR ROTATION ABOUT SUCH AXIS, SAID BRAKING HEAD MEANS ALSO INCLUDING AN OUTER GRIPPER ROLL RING MOUNTING A PLURALITY OF OUTER GRIPPER ROLLS FOR ENGAGING THE OUTER SURFACE OF THE TUBE WHICH IS EXTERIOR TO AND SUPPORTED INTERIORLY BY SAID BACK-UP ROLL MEANS, SAID GRIPPER ROLL RING BEING SITUATED EXTERIOR TO SUCH TUBE AND MOUNTED FOR ANGULAR MOVEMENT ABOUT SUCH AXIS, AND MEANS FOR ROTATING SAID GRIPPER ROLL RING WHEREBY TO PREVENT INJURY TO THE TUBE THROUGH TWISTING IN THE REGION INTERMEDIATE SAID TUBE FORMER AND SAID CORRUGATING HEAD.