Patent GB-1378020-A (GB)
Title: Gas cutting machine
Inventor: INOMATA N
IPC: B23Q35/04
Filed: 1972-11-09
Abstract: 1378020 Gas cutting NIPPON KOKAN KK 9 Nov 1972 [10 Nov 1971] 51762/72 Heading B3V [Also in Division G3]  A gas cutting machine for cutting a blockstructure 61 comprises a carriage 11 movable in a first direction X, a cutting torch 40 on a head 38 extending in a second direction Z perpendicular to the first and rotatable about the axis of a first shaft 28 extending in the second direction Z, a sensor 57 connected to a second shaft 23 parallel to the first shaft 28 for sensing the outer periphery 62a of the structure 61 and a control mechanism 19 movable in a third direction Y perpendicular to the other directions X, Z for controlling movement of the carriage 11 and for rotating the sensor 57 and torch head 38 through equal angles so that the torch head 38 is moved at a constant speed along the surface to be cut. The shafts 23, 28 are rotatable in the same direction and through the same angle by a servomotor 24 through gears 25, 26, 30, 29 mounted in a control box 19 which is movable along a pole 17 by a servomotor 20 having a gear 22 engaged with a rack 21. The gear 25 of the motor 24 engages a gear 49 of a resolver 47 and, via the gear 26 on the shaft 23, a gear 48 of a resolver 46. The other end of the shaft 28 is connected to a member 31 upon which is mounted for vertical movement by a servomotor 35 a member 32 mounting piston-andcylinder assemblies 36, 37 carrying torch heads 38, 39. A cutting torch 40, 43, an inclined edge preparation torch 41, 44 and a differential transformer 42, 45 for keeping the distance between the torch and the workpiece constant are mounted on each torch head 38, 39. The other end of the shaft 23 is connected to an arcuate piston-and-cylinder 27, the arcuate piston of which is connected at one end to an L-shaped sensor plate 57 pivotable about a contact 58 and carrying differential transformers 59, 60 each provided with a stylus 59a, 60a for following the underside of a workpiece 61. The arcuate piston is biased in one direction by compressed air introduced through a duct 52. If the transformer stylus 59a moves due to the curvature of the workpiece 61 when the carriage 11 is moved by a servomotor 13 and drive transmission 14, a voltage is produced from the transformer 59 to drive the servomotor 24 causing the shafts 23, 28 and the sensor 57 to rotate until the transformer voltage is reduced to zero. The resolvers 46, 47 are also rotated causing the speeds of the carriage 11 and control box 19 to be altered so that the sensor 57 follows the workpiece at a desired speed. The piston-and-cylinder assembly 27 and the shaft 23 are moved in a vertical plane (Fig. 1, not shown) and the arcuate piston moved within its cylinder when the transformer stylus 60a moves vertically. When a plate 64 of the workpiece 61 is cut by the torch head 38, a voltage is produced from the transformer 42 on the head 38 if its stylus 42a following the plate surface is displaced causing the slidable member 32 to be moved by the servomotor 35 so as to maintain the distance between the torch 40 and plate 64 constant. Similarly, when a web 63 of the workpiece 61 is cut by the head 39, the carriage servomotor 13 is controlled by the transformer 45 to vary the speed of the carriage 11 to maintain the desired distance of the torch 43. An inclined cut (F 3 -F 3 ) (Fig. 15, not shown) may be made in the web 63 by inclining the pole 17 by an hydraulic jack 18.