Patent GB-601982-A (GB)
Title: Improved method of and apparatus for removing metal from ferrous metal bodies
IPC: B23K7/08
Filed: 1945-04-25
Abstract: 601,982. Cutting by fusion. LINDE AIR PRODUCTS CO. April 25, 1945, No. 10375. Convention date, July 28, 1944. [Class 83 (iv)] [Also in Groups XXIX and XXX] In desurfacing, flame cutting, flame boring, machining and like operations, a jet of oxygen is directed against the surface of a ferrous metal body readily amenable to flame machining, concurrent with a combustible powder which ignites to raise the temperature of the metal quickly preparatory to the metal removing operation, the powder being interrupted after the surface of the body has become ignited. The powder may consist of powdered iron, low carbon steel, ferromanganese or cast iron, aluminium or manganese. In a machine particularly for cutting deep slots &c. in rods, bars or the like, a cutting blow-pipe 11, Fig. 1, has a central passage for conveying oxygen through a conduit 29 to the heating zone ; a plurality of annularly spaced passages for admitting gases from a conduit 25 to pre-heat the combustion zone and a set of annularly spaced passages arranged on a smaller diameter than the pre-heat outlet, at the nozzle end, for conducting combustible powders supplied through conduits 43 and 39 from a container 33 which may have an inlet 35 attached for feeding gas through a valve to carry the powders to the work zone. Oxygen and acetylene are supplied through hoses 17 and 19 controlled by valves 21 and 23 respectively after which a portion of the oxygen is mixed with acetylene and the remainder admitted to nozzle 27 for the cutting operation. In use, the preheating flames are directed on the work zone and the oxygen and powder control levers 31 and 51 depressed. As the powder reaches the end of the nozzle it combines with the oxygen and ignites rapidly to propagate the ignition and burning action on the work ; the nozzle being held, for cutting or deep boring, at an angle in the region of 90 degrees. In a modified form of nozzle as shown in Fig. 5, the powder reaches the work through an outside conduit 73 so shaped that its influence may cause the powder to feed into the leading side of the oxygen jet. In a further modification, the central oxygen passage has a series of small ports in its periphery which admit combustible powder from connecting passages and the mixture of powder and oxygen is supplemented as the stream reaches the end of the nozzle by the addition of acetylene which is supplied from passages having outlets just inside the tip of the nozzle. Control levers increase the supplies of power &c. according to the speed and depth of cut required. The apparatus may be mounted on a carriage for performing cutting &c. operations on a series of work-pieces. In another embodiment of the invention particularly for flame de-surfacing, a series of powder outlet nozzles 147, Fig. 12, are arranged in a block 141 which is fitted with passages 142 for coolant flow. The powder is supplied to a central header passage 143 from inlet tubes 149, 150 and admitted to upper bushes 145 which are normally closed by pistons 151. The pistons are mounted on the same axis and above the outlet passages, and have stems 155 adjustably secured to a yoke 161 by nuts 163. The yoke is attached at its centre to the piston of an air cylinder 173 and opens each outlet port against the action of springs 159 interposed between each piston and bushes 157. The block and air cylinder are mounted on a shoe 131 which has a series of nozzles 127 arranged along its bottom side ; each nozzle. being in line with a corresponding powder outlet and having a central flat passage for the oxygen stream inside a ring of annular passages for pre-heating gases. In operation, the unit is positioned on the work which is movable on a roller 119 and preheating gas is supplied and ignited ; compressed air is admitted to the air cylinder raising the piston and allowing combustible powder to flow through the outlet ; after which the oxygen flow is started and the powder ignited to commence the metal removing operation. In a modified form of powder feed, a U-section channel 203, Fig. 14, is covered by a flexible diaphragm 205 which is clamped between the channel and a valve stem housing 225. Pistons 227 are normally held against the openings in powder outlets 204 and are screwed through the diaphragm to an upper valve member 229 having a stem 233 adjustably secured by a nut 237 to a yoke 239 which is pivoted at its opposite edge for movement by the piston of an air cylinder 245. Powder is supplied to the header chamber through conduit 209 and an air pipe 261 is provided to admit compressed air, or gas and supplement the action of the powder-laden gas. In a further modification, the spring-loaded valve guide is dispensed with and the diaphragm is clamped between two U-section housings, the lower of which is supplied with powder and contains a number of powder outlets, each closed by a piston which is secured at its upper end to a valve guide member ; the diaphragm being clamped between the two parts at its centre. The upper chamber is connected through a three-way valve to a source of compressed air which normally maintains pressure on the diaphragm to keep the powder outlet closed by the piston. When powder is required, the three-way valve is operated to bleed air from the upper chamber and as this proceeds the powder pressure forces the diaphragm up to retract the piston and clear the powder outlet. A control system to ensure proper sequence of the powder and gas supplies is shown in Fig. 18 in which the operation is as follows. The main switch 177 and starting switch 178 are closed to start a timing motor 179 having a shaft 180 with timing cams 181-184 mounted thereon. Cam 181 closes switch 185 energizing solenoid 186 to open the pre-heat gas control valve 187 and start the flow of pre-heating gases, which are ignited by pilot flames. After a pre-determined interval, cam 182 closes switch 188 energizing solenoid 189 to operate the three-way valve and admit air to the air cylinder ; this raises the piston 165 to permit powder flow to commence. Cam 183 then closes switch 192 to energize solenoid 193 and open a valve 195 controlling oxygen flow. Movement of the work is started after a pre-determined interval by cam 184 which closes switch 197 and energizes a motor 199 to rotate the driving roll 119, Fig. 12. Upon the conclusion of the metalremoving operation, the main switch 177 is opened and stops everything. The cam 182 is designed to open automatically switch 188, as the driving roll commences rotation, deenergizing solenoid 189, reversing the air valve and bleeding air from the cylinder so that the piston returns to its normal position and powder supply is cut off by blocking of the outlet nozzle. The operator then opens the starting switch to stop the timing motor leaving valves 187 and 195 and the motor 199 in a condition to complete the metal-removing operation. Specifications 550,683, 568,397 and 568,720 are referred to. The Specification as open to inspection under Sect. 91 states that the powder supply may be used throughout the metal-removing operation. The starting switch is in this case opened directly the driving roll rotates to stop the timing motor with all contacts closed. This subject-matter does not appear in the Specification as accepted.