Patent GB-568720-A (GB)
Title: Improvements in the flame machining or flame cutting of metal bodies
IPC: B23K7/06
Filed: 1944-05-13
Abstract: 568,720. Dividing and removing surface metal by fusion. LINDE AIR PRODUCTS CO. May 13, 1944, Nos. 9211, 9212 and 9213. Convention dates, April 21, 1943. [Class 83 (iv)] [Also in Group XI] In a method of flame machining or cutting metal bodies having a composition which resists or hinders the normal cutting action of the oxygen jet and in which finely-divided oxidisable adjuvant material is introduced into the zone of action of the jet to produce reaction products sufficiently fluid to permit removal thereof when relative movement is effected between the body and the jet, the adjuvant material is introduced into the oxygen jet within a nozzle from a number of orifices disposed about the periphery of the jet so as to discharge a uniform mixture of oxidising gas and powder. In another method, the powder may be fed centrally into an annular stream of oxidising gas. The metal body may consist of chromiumsteel, cast-iron, or non-ferrous metals such as copper, aluminium, nickel, and alloys such as nickel-molybdenum, nickelmolybdenum - chromium, cobalt - chromium - tungsten or silicon bronze, and the powder may consist of aluminium, iron, steel, or cast-iron. When using powdered cast-iron or steel containing more than 0.2 per cent of carbon, this may be mixed with 10 to 50 per cent of ferromanganese. In one form, a copper nozzle 11 which may have a chromium-plated bore or contain an abrasion resisting lever 12 of beryllium-copper alloy or ceramic material and which has a number of passages 10 for preheating gas mixture, is secured in a head H with a chamber 18 having a plugged end 24 from which projects a tube T extending into the passage of the nozzle and terminating at a point sufficiently remote from the discharge end to ensure uniform mixing of oxygen and powder. The oxygen is led through the tube T from a conduit 25 and the powder, which is supplied to the chamber 18 from a hopper through a valved tube 16, is aspirated round the outside of the tube T by the suction produced as the oxygen expands from the tube T. The tube T has on its forward end an external flange 27 provided with a number of longitudinal grooves 28 to minimize the tendency for the powder to burn back within the nozzle. For flame-cutting, the powder may be passed through the tube T and the oxygen through the annular passage 29. In Fig. 3, the central oxygen passage 32 is circular at the rear end, but tapers forwardly to a wide, thin, slot-like orifice and the oxygen tube has a rear portion of large diameter passing through the rear of the head and tapering down to a small diameter front portion so as to increase the velocity of oxygen before it is discharged into the passage 32. In Fig. 5, the tube 51 is carried by the nozzle 44 and has flanges at each end to leave an annular space 56, the front flange having a number of outlet grooves. Powder from a closed hopper provided with an inlet pipe for gas under pressure and connected to the blow-pipe by flexible hose, passes through the valved pipe 57 into a chamber 59 which communicates with the annular space 56 by a number of inclined ports 50 in the nozzle. The rotary valve 67 is operated by a rod or wire attached to a crank on the valve stem. In order that the operator may control in unison both the flow of powder and of oxygen, a lever 74, Fig. 8, pivoted to the blow-pipe handle engages at its rear end the stem of a spring-closed oxygen-coated valve, and is connected by a link 80 to a spring- controlled rotary element 77 connected by a turn-buckle 81 to the wire 72 attached to the crank 71 on the valve controlling the supply of powder simultaneously or at different times. The nozzle 83, Fig. 9, may have passages 85 for supply of combustible fluid only, such as acetylene gas, which is deflected by an annular lip 84 into the central oxygen stream so as to mix the gases outside the nozzle. In this case, a greater number of powder inlet ports 86 are used than in the previous form. In a, further form, Fig. 11, the inclined powder ports 99 are located outside the head 89 and the powder distributing chamber 101 is formed within a hollow collar 102 welded to the outside of the nozzle. In a modification of this form, Fig. 13, a ring 110 with annular powder-distributing chamber and with a number of short ducts 112 leading therefrom, may be rotated between guide rollers 107, 108 to contact the supply to the inlet ports 113. A pin 117 projecting from the ring 110 may engage one of a pair of stop pins 118 carried by the collar 107. In another form, Fig. 16, the powder feed tube 122 may contain a feed screw carried by a flexible shaft 141 connected to a motor M so as to feed powder positively and uniformly into the annular space round the central oxygen tube. The oxygen valve control lever 143 carries a link 145 for operating a switch 144 controlling the motor, so as to provide common control for the oxygen and powder. A number of blowpipe units may be mounted side-by-side on a shoe S, Fig. 19, carried by a travelling support. The powder for each blow-pipe is supplied to a separate chamber 149 by conduits 150 from a closed hopper, a gas pressure being maintained above the level of the powder in the hopper. The powder is positively fed through the passages 163 by hollow feed screws 152 driven by worm gear 157, 158 from a single shaft 156 passing along the width of the multi-blow-pipe unit. Specification 568,397 is referred to.