Fin forming devices

Claim 1

IN A MACHINE FOR FORMING A SPIRALLY WOUND FIN ABOUT A TUBE, MEANS FOR FEEDING AND ROTATING A TUBE THROUGH THE MACHINE, MEANS FOR FEEDING SHEET METAL STOCK UNDER TENSION TO AN ASSEMBLY OF FIN FABRICATING ROLLS, SAID ASSEMBLY FORMING A SUCCESSION OF SPIRALLY WOUND FINS ABOUT THE TUBE AS IT ADVANCES THROUGH THE MACHINE, SAID ASSEMBLY INCLUDING A DISC ROLL WITH A PLANE SURFACE AND AN OUTER FLANGE WHICH EXTENDS BETWEEN THE FIN BEING FORMED AND THE ADJACENT PREVIOUSLY FORMED FIN, A BEVELED FORMING ROLL COOPERATING WITH SAID DISC ROLL AND BETWEEN WHICH THE SHEET METAL STOCK IS ENGAGED, SAID FORMING ROLL HAVING A DIAMETER LESS THAN HALF THAT OF THE DIAMETER OF THE DISC ROLL, A BACK ROLL ROTATING AGAINST THE FORMING ROLL ON A SIDE THEREOF OPPOSED TO THE DISC ROLL, THE PRESSURE EXERTED BY THE BEVELED FORMING ROLL BEING RESISTED BY SAID BACK ROLL SO THAT THE DISC ROLL WILL NOT BE INJURED DESPITE GREAT PRESSURES EXERTED THEREON BY THE BEVELED FORMING ROLL, SAID MEANS FOR ADVANCING AND ROTATING THE TUBE UPON WHICH THE RIBBON IS FORMED BEING OPERATIVE RESPONSIVE TO THE TENSION OF THE RIBBON AS IT IS PLACED UPON THE TUBE SO THAT SAID MEANS CONTINUOUSLY SLIPS, WITH RESPECT TO THE TUBE.