Patent GB-941304-A (GB)
Title: Improvements relating to an apparatus for following the projected path of a circle on a surface
Inventor: GETHIN JOHN WESTBURY
IPC: B23K7/00
Filed: 1958-08-28
Abstract: 941,304. Cutting by fusion. JOHN THOMPSON (WOLVERHAMPTON) Ltd. Nov. 30, 1959 [Aug. 28, 1958], No. 27690/58. Heading B3V. [Also in Division F2] Apparatus, particularly a flame cutting torch 67, for following the path of a circle on a surface 68 inclined at an acute angle to the axis passing through the centre of the circle and normal to its plane, comprises a base 2, 3 fixable to the surface, a rotatable shaft 21 extending along the axis, means 67 on the shaft for describing the projected path as the shaft is rotated and mechanism 17 for maintaining the means 67 at a fixed relationship to the surface whilst describing the path. The invention is of particular use in flame-cutting holes for branch pipes in the walls or ends 1 of pressure vessels which walls may be flat or curved. A base plate 2 of U-shape is secured to the plate 1 to be cut by three permanent magnets 3 having a universal connection 4 with the base plate and release screws 5. The base plate has pivoted thereto at 9, Fig. 1 (not shown), a bridge 6 lockable in its horizontal adjusted position, as shown on a spirit level 16, Fig. 1 (not shown), by a clamp arm 11 and bolt 14. Bridge 6 carries a housing 17 for an adjustable swash-plate assembly 24, Fig. 3, whereby as the shaft 21 is rotated through a releasable coupling 54, 59 and gearing 51, 52 by a pneumatic motor 53 it is also reciprocated by a predetermined amount determined by the adjustment 37, 38 of the swash plate. Shaft 21 has an arm 60 along which is radially adjustable, by rack and pinion mechanism 62, a carrier 61 for a slide 63 supporting a nozzle mount 65 for the cutting torch 67. The angular position of the torch is adjustable during rotation of the shaft, manually by a rack and pinion mechanism 66 for cutting parallel or bevelled edges 69; alternatively it may be adjusted automatically by a servomotor. In another embodiment, Fig. 5, for cutting steeply inclined plates, an extension 20 of the shaft 21 carries a worm-wheel 76 engaging a worm 77 driven by an electric motor 78, Fig. 4 (not shown). The shaft is mounted in bearings in a tube 69 which can be raised and lowered for varying the height of the cutting torch, by a rack 73 and pinion 74 driven by a motor 75, Fig. 4 (not shown). Worm-wheel 76 mounts a slide 80 and eccentric pin 79 adjustable radially by a screw 81. The pin 79 engages in a slot in a first slide 83 carrying an arm 86 passing with clearance through an aperture 85 in a second slide 84. The latter carries a follower roller 87 engaging an axial cam surface 88, and a pair of micro-switches 90, 91, controlling the height adjusting motor. Thus, as the shaft 20 carrying the cutting torch is rotated, relative movement between the slides 83, 84 resulting from the cam 88 and follower 87, causes arm 86 to actuate one or other of the switches 90, 91, for raising or lowering the torch. In a modification the pinion 74 may be driven through a differential mechanism by a pair of pneumatic motors controlled respectively by valves which replace the switches 90, 91.