Flying hot saw

Claim 1

IN COMBINATION WITH A BUTT WELD PIPE MILL FOR CONTINUOUSLY PRODUCING WELDED PIPE, A MOTOR FOR DRIVING THE MILL, A FLYING HOT SAW FOR SERVING THE PIPE INTO LENGTHS AS IT LEAVES THE MILL, THE SAW COMPRISING A ROTARY CUTTING TOOL, A PAIR OF CRANKS FOR CARRYING THE CUTTING TOOL INA CIRCULAR ORBIT AND MEANS FOR GUIDING THE PIPE EMERGING FROM THE MILL INTO THE PATH OF THE CUTTING IN ITS ORBIT THEREBY TO SERVE THE PIPE, THE LENGTH OF THE PIECES CUT BY THE SAW VARYING WITH THE RATIO BETWEEN THE SPEED OF THE PIPE ENTERING THE SAW AND THE NUMBER OF REVOLUTIONS PER MINUTE OF THE CUTTING TOOL IN ITS ORBIT, MEANS FOR DRIVING THE CUTTING TOOL IN ITS ORBIT COMPRISING A MAIN DRIVE SHAFT, A P.I.V. DRIVEN BY THE MAIN DRIVE SHAFT AND A POWER TRAIN BETWEEN THE P.I.V. AND THE CRANK ARMS WHEREBY FOR A GIVEN ADJUSTMENT OF THE P.I.V., THE NUMBER OF REVOLUTIONS PER MINUTE OF THE CUTTING TOOL IN ITS ORBIT IS DETERMINED BY THE SPEED OF SAID MAIN DRIVE SHAFT; THE IMPROVEMENT COMPRISING MEANS FOR DRIVING SAID MAIN DRIVE SHAFT AND FOR MAINTAINING THE RATIO BETWEEN THE SPEED OF THE MAIN DRIVE SHAFT AND THE SPEED OF THE PIPE ENTERING THE SAW SUBSTANTIALLY CONSTANT COMPRISING A DIFFERENTIAL HAVING A MAIN POWER INPUT AND AN AXIALLY INPUT AND AN OUTPUT CONNECTED TO SAID MAIN DRIVE SHAFT, A MECHANICAL CONNECTION BETWEEN SAID MOTOR AND SAID MAIN POWER INPUT FOR DRIVING SAID MAIN POWER INPUT AT A SPEED SUBSTANTIALLY PROPORTIONAL TO THE SPEED AT WHICH SAID MILL IS DRIVEN AND CONTROL MEANS FOR DRIVING SAID AUXILIARY INPUT AT A SPEED SUCH THAT THE OUTPUT OF SAID DIFFERENTIAL IS MAINTAINED ACCURATELY AT A PREDETERMINED RATIO WITH RESPECT TO THE SPEED OF THE PIPE ENTERING SAID SAW, SAID CONTROL MEANS COMPRISING A ROLL ENGAGING AND DRIVEN BY THE PIPE ENTERING SAID SAW, A SYNCHRO-GENERATOR DRIVEN BY THE PIPE ENTERING PUT OF THE SYNCHRO-GENERATOR BEING CONNECTED TO A SYNCHROCONTROL TRANSFORMER DRIVEN BY SAID MAIN DRIVE SHAFT WHEREBY THE OUTPUT OF SAID SYNCHRO-CONTROL TRANSFORMER PROVIDES AN ERROR SIGNAL PROPORTIONAL TO DIFFERENCES IN SPEED BETWEEN SAID MAIN DRIVE SHAFT AND SAID PIPE ENTERING SAID SAW, MEANS FOR AMPLIFYING SAID ERROR SIGNAL AND AN ELECTRIC DIFFERENTIAL DRIVE CONTROLLED BY SAID ERROR SIGNAL AND CONNECTED TO DRIVE SAID AUXILIARY INPUT TO SAID DIFFERENTIAL.