Patent GB-532155-A (GB)
Title: Improvements in or relating to pipe screw threading apparatus
IPC: B23G1/22
Filed: 1939-08-18
Abstract: 532,155. Screwing. BENNINGHOFF, W. L. Aug. 18, 1939, No. 23861. Convention date, Sept. 6, 1938. [Class 83 (iii)] In a machine for cutting screw-threads on pipes, a frame carries a rotatable and axially movable die-head and also two work-holding devices, of which the first is adjacent the diehead and holds the pipe-end in alignment with the dies but has a gripping pressure insufficient to distort the pipe-end being secured. whilst the second grips the pipe more firmly to prevent it from rotating but is spaced from the die-head a sufficient distance to prevent any distortions produced thereby from affecting the thread, the second work-holder being floatingly mounted on the frame so as to accommodate itself to bends in the pipe. A self-opening and taper threading die-head 6 is rotatably mounted on a slide 5 carried by the frame 2 and is fed and rotated at working speeds by a motor 9 or is traversed rapidly in either direction by a motor 16, each motor operating through reduction gears (not shown). The work-holders 24, 25 are carried by a bracket 23 secured to the frame 2, the former having radial dogs 27, Figs. 4 and 8, adjustably secured at 30 to jaws 29 which are actuated by links 31 connected to a rotatable ring 33. The jaws are slidable in radial slots in a body 26 secured rigidly to the bracket 23 and are guided by segmental plates 26a. A hydraulic cylinder 35 is pivoted to a bracket 38 attached to the bracket 23 and its piston rod 37 is pivoted to a lever 40 fulcrumed at 41 to the bracket 38 and connected by a link 42 to the ring 33. Actuation of the cylinder 35 thus grips or releases the work. The rear work-holder has radial dogs 57 actuated similarly to the dogs 2,7, but its body 43 which carries the bracket 44 supporting the clamping cylinder 64 is floatingly mounted and is balanced in a vertical direction by a spring 51 adjustable at 49a and pressing on a lever 46 pivoted at 47 on the bracket 23. The lever engages a slot 62 in the bracket 44. Rotation of the body 43 is prevented by a ring 53 having horizontal keys 53b engaging a in a plate 54 attached to the body and vertical keys 53c engaging keyways in the bracket 23. The weight of the ring 53 is balanced by springs 75, -Fig. 11, adjustable at 76 and acting through knife edges 77 on levers 71 pivoted on the bracket 23 at 72. The levers engage at 71a on shoulders in the ring 55 and the abutment screws-73 of the springs are pivoted at 74 to the bracket 23. The free end of the work is supported on adjustable rollers 91 and in use, the holder 24 centralizes the end of the work W in relation to the die-head 6 whilst the holder 25 may adjust itself to slight bends in the pipe, the screw thread formed being parallel to the main axis of the pipe extending from the die-head to the rear support 91. The clamping cylinders 35, 64 are actuated with hydraulic fluid supplied individually from pumps 78, 78' driven .by a motor 79. The flow and return pipes are controlled by valve boxes 81, 81<SP>1</SP>, actuated by hand levers 81a, and the clamping pressures are adjusted by spring relief valves 86, 86<SP>1</SP>. Some of the rollers 91 may be motor driven for feeding the work into the machine.