Patent ID: 7380430
Filing Date: 2008-06-03
Classification: B21D

Abstract:
1. A rotary draw tube bender for bending tubular workpieces such as a tube or pipe, each workpiece having a uniform outer diameter, said rotary draw tube bender comprising: at least one die set including a counter die and a plurality of bending dies with different and progressively increasing bend radii, two of said bending dies having an incremental difference in bend radius, said bending dies having a circumferential concave groove and said counter-die having a linear concave groove, said grooves being sized and shaped to substantially flushly engage the workpiece; a spindle rotatable about an axis of rotation and adapted to securely receive a selected bending die, said spindle and selected bending die rotating in unison; an arm extending radially from and rotatable about said axis of rotation, said arm rotating independently of said spindle and having a radial axis that intersects said axis of rotation, said arm having an alignment mechanism with a radial track that slidably receives a counter-die assembly adapted to receive a selected counter-die, said counter-die assembly having ratchet teeth, said track and teeth being substantially parallel to said radial axis, each of said teeth having a unit length that is an integer fraction of said incremental difference in bend radius of said bending dies, said alignment mechanism including a ratchet assembly to incrementally radially align said counter-die with said bending die to accurately set a die gap between them; a drive mechanism including first and second hydraulic cylinders positioned about a line of symmetry that intersects said axis of rotation, said drive mechanism having a home position, said first hydraulic cylinder having a drive side, a return side and a first drive rod connected to said spindle, said first drive rod being movable between retracted and extended positions to rotate said spindle, and said second hydraulic cylinder having a drive side, a return side and a second drive rod connected to said arm, said second drive rod being movable between retracted and extended positions to rotate said arm in an opposite direction relative to said rotation of said spindle; a bend angle setting device having a limit switch and a dial with a triggering device, said dial and triggering device being selectively rotatable relative to said limit switch to position said triggering device at a desired bend angle position relative to said limit switch, said limit switch triggering when said triggering device is angularly aligned with said limit switch; a pedal control unit including a drive cycle pedal and a return cycle pedal, each of said pedals being biased into a disengaged position and selectively movable to an engaged position; an electro-hydraulic control system having an electrically powered pump and a control valve in electrical communication with said pedal control unit, said control valve having a drive cycle path and a return cycle path, said pump transmitting pressurized hydraulic fluid to said control valve, said control valve directing said pressurized hydraulic fluid to said drive side of said hydraulic cylinders to extend said drive rods when said drive cycle pedal is engaged, and said control valve directing said pressurized fluid to said return side of said hydraulic cylinders to retract said drive rods when said return cycle pedal is engaged; and, wherein engaging said drive cycle pedal simultaneously extends said drive rods at equal rates to rotate said bending die in a first direction and said counter-die in an opposite direction until said limit switch is triggered when a desired angular bend is formed in the workpiece, and wherein moving said return cycle pedal to said engaged position simultaneously retracts said drive rods and rotates said bending die and counter-die to return said drive mechanism to its said home position.