Pipe Bending Machine

Abstract

A pipe bending machine has a beam mounted in see-saw pivotal relation on a fulcrum and spaced apart cradles support the pipe. An actuator initially drives the second cradle and the beam apart to pivot the pipe about the first cradle until the pipe is in contact with the die and thereafter drives the beam away from the second cradle to bend the pipe against the die. The mechanical advantage of the levered operation requires only a single actuator motion to bend the pipe. An external mandrel allows the pipe to be incrementally fed through the bending machine and secures the pipe against cross-sectional distortion during the bending process.

1 . For use in a machine for bending pipe, a mandrel comprising a plurality of vertebra, each said vertebra having a pair of jaws, each jaw of said pair being independently pivotally mounted whereby said pair of jaws is at rest in response to gravity in a sufficiently open condition to receive a pipe therein, each said pair of jaws having an internal contour shaped at least in part to cause said pair of jaws to close on and mate against an exterior wall of the pipe in response to the pipe imposing force against said internal contour whereby the mandrel substantially maintains a cross-sectional shape of the pipe during bending thereof. 
     
     
         2 . A mandrel according to  claim 1 , said plurality of vertebra forming a spinal column which, with said vertebrae mated against the pipe in said closed condition, is free to conform to a bending arc of the pipe. 
     
     
         3 . For use in a machine for bending pipe, a mandrel comprising a plurality of vertebra, each said vertebra having a pair of jaws, each jaw of said pair being independently pivotally mounted whereby each said pair of jaws is at rest in response to gravity in a sufficiently open condition to transversely receive a pipe being elevated into said pair of jaws, each said pair of jaws having an upper internal contour shaped to cause said pair of jaws to rotate into a closed condition on the pipe in response to the pipe being elevated against said upper internal contour and to bear against an exterior wall of the pipe in said closed condition to substantially maintain a cross-sectional shape of the pipe during bending thereof. 
     
     
         4 . A mandrel according to  claim 3 , said plurality of vertebra forming a spinal column which, with said vertebrae bearing against the pipe in said closed condition, is free to conform to a bending arc of the pipe. 
     
     
         5 . For use in bending pipe, a machine comprising:
 a frame;   a plurality of vertebra mounted on said frame to form a spinal column which is free to conform to a bending arc of the pipe; and   a lower trough movably mounted in said frame to bend the pipe against said spinal column;   each said vertebra having a pair of jaws, each jaw of said pair being independently pivotally mounted whereby said pair of jaws is at rest in response to gravity in a sufficiently open condition to transversely receive the pipe as the pipe is elevated into said pair of jaws, each said pair of jaws having an upper internal contour shaped to cause said pair of jaws to rotate into a closed condition on the pipe in response to the pipe being elevated against said upper internal contour and each said pair of jaws having an internal contour shaped to bear against an exterior wall of the pipe in said closed condition to substantially maintain a cross-sectional shape of the pipe during bending thereof.   
     
     
         6 . For use in bending pipe, a mandrel comprising:
 a plurality of pairs of members;   each said pair having an inner contour shaped to mate against an exterior wall of the pipe to substantially maintain a cross-sectional shape of the pipe during bending thereof; and   each said pair having an inner contour shaped to urge said members to mate against the exterior wall of the pipe as the pipe is impelled against said urging inner contour.   
     
     
         7 . A mandrel according to  claim 6 , said members of each said pair having their respective said mating surfaces diametrically opposed when mated against the pipe. 
     
     
         8 . For use in bending pipe, a machine comprising:
 a frame;   an upper die mounted in said frame;   a lower trough movably mounted in said frame to bend the pipe against a surface of said die;   a plurality of pairs of members mounted on said frame to freely conform to a bending arc of the pipe, each said pair having an inner contour shaped to mate against an exterior wall of the pipe to substantially maintain a cross-sectional shape of the pipe during operation of said trough to bend the pipe against said die and having an inner contour shaped to urge said members to mate against the exterior wall of the pipe as the pipe is impelled against said urging inner contour.   
     
     
         9 . A machine according to  claim 8 , said members of each said pair having their respective said mating surfaces diametrically opposed when mated against the pipe. 
     
     
         10 . A machine according to  claim 9 , said diametrically opposed surfaces being on opposite sides of a bending plane of the pipe. 
     
     
         11 . A machine according to  claim 10 , said bending plane being a vertical plane and said opposing pairs of members being aligned for substantially horizontal mating and releasing motion. 
     
     
         12 . A method for bending pipe comprising the steps of:
 urging the pipe against a bending die; and   simultaneously girthing an exterior wall of the pipe to substantially maintain a cross-sectional shape of the pipe during bending.   
     
     
         13 . A method according to  claim 12 , said step of girthing comprising mating opposing members against opposite sides of the pipe. 
     
     
         14 . A method according to  claim 13 , said opposing members being on opposite sides of a pipe bending plane. 
     
     
         15 . A machine for bending pipe comprising:
 a beam mounted in see-saw pivotal relation on a fulcrum;   first and second spaced apart cradles aligned to support the pipe, said first cradle being mounted on said beam on one side of said fulcrum and said second cradle being mounted on an actuator mounted on said beam on an opposite side of said fulcrum; and   a die positioned between said cradles;   said actuator initially driving said second cradle and said beam apart to pivot the pipe about said first cradle until the pipe is in contact with said die and thereafter driving said beam second cradle away from said beam to bend the pipe against said die.   
     
     
         16 . A machine according to  claim 15 , a force exerted on said second cradle by said actuator being insufficient to bend the pipe before the pipe contacts said die driving and being sufficient by application of mechanical advantage on said first cradle to bend the pipe after the pipe contacts said die. 
     
     
         17 . A machine according to  claim 16 , said mechanical advantage being leverage created by said beam and said fulcrum. 
     
     
         18 . A machine according to  claim 15 , said actuator comprising an hydraulic cylinder. 
     
     
         19 . A machine according to  claim 15 , said actuator comprising a screw drive. 
     
     
         20 . A machine according to  claim 15  further comprising a radial control arm pivotally connected at one end to said beam and at another end to said cradle, said arm being biased to a neutral telescopic condition and responsive to expansive and compressive forces applied thereto by said second cradle to exert compressive and expansive counter-forces against said second cradle.