GB956488A - Improvements in or relating to oxygen jet cutting machines - Google Patents

Abstract

956,488. Cutting by fusion. HANCOCK & CO. (ENGINEERS) Ltd. Dec. 14, 1962 [Sept. 14, 1961], No. 32936/61. Heading B3V. [Also in Division G3] In an oxygen jet profile cutting machine using a scale drawing traced by an electronic follower 31 having a lead over the cutting torch 19 and whose movements on a drawing are followed by the cutting torch multiplied by the scale ratio, the image of that portion of the drawing being followed is enlarged by the scale ratio before being applied to the photo-electric device 79, Fig. 6, of the follower. This is stated to reduce errors of contour due to the scale multiplication. The follower has a magnifying lens 76 which focuses the enlarged image on to the bottom surface 78 of a photo-transistor 79 supported by a spring arm 80 on a rotatable tube 81 and vibrated at supply mains frequency by an A.C. electromagnet so as to scan the image. Arm 80 gives the photo-transistor 79 the desired lead so that it moves in an arc when the tube 81 is rotated by the steering motor. Signals from the phototransistor are applied to one stator winding of a two-phase steering motor whose other winding is supplied with a reference voltage. The cutting machine, Fig. 1, comprises a longitudinal carriage 15 driven by motor 41 along rails 13 and carrying a transverse carriage 17 driven by motor 42 and supporting the cutting torch 19. To prevent slip the carriage 15, 17 may be driven through rack and pinion gearing. The plate like workpiece 21 rests on supports 22. The drawing rests on a table 28 movable along longitudinal rails 27 supported on a transversely movable drawing carriage 25 running on transverse rails 24 of a frame 23 secured to the main carriage 15. Rotational movements of the steering motor control a two-arm potentiometer whose two arms control respectively, through amplifiers, the carriage motors 41, 42. The speeds of these motors may be varied by a potentiometer for adjusting the cutting speed. Longitudinal movements of the main carriage 15 are fed back to the longitudinal drawing carriage 28 through 10: 1 reduction gearing 35, 36, 38 and rack 39; transverse movements of the carriage 17 are fed back to the transverse drawing carriage 25 with a 10: 1 reduction by means of pinion 34 and rack 32. In a modification, Figs. 2, 3 (not shown), the drawing carriage 28 has longitudinal movement only whilst the follower 31 is mounted on wheels for transverse movement. In another embodiment, Figs. 4, 5 (not shown), the follower mechanism is separate from the cutting machine and the two are interconnected by a magslip system.