Patent GB-737064-A (GB)
Title: Continuous casting
IPC: B22D11/14
Filed: 1953-10-08
Abstract: 737,064. Continuous-casting machines. BABCOCK & WILCOX CO. Oct. 8, 1953 [Oct. 23, 1952], No. 27681/53. Class 83 (1). A process of continuously casting in a metal liquid-cooled mould, which comprises continuously lip-pouring a stream of molten metal to the mould from a metal pool maintained above the normal maximum molten-metal level in the mould, and circulating liquid-coolant at high velocity through a laterally confined space around the mould to form an embryo casting within the mould, is characterized by maintaining a protective non-oxidizing atmosphere about the molten metal delivered to the mould, discharging a controlled flow of cooling liquid against the embryo casting issuing from said mould, guiding and restraining the movement of said casting between the mould and the withdrawal mechanism, and cyclically varying the molten-metal level in said mould by cyclically operating the withdrawal mechanism. The cyclical operation of the withdrawal mechanism may comprise starting such mechanism when the molten metal reaches a predetermined position in the mould and stopping it after a predetermined downward movement of the casting, or alternatively a slow and fast withdrawal of the casting from the mould, either manually or automatically as described in Specification 686,033, may be utilized. The apparatus comprises a watercooled mould 13, a melting and pouring furnace 11, a tun-dish 12 between the furnace and the mould, a withdrawal mechanism 14, guiding and restraining rollers 92, and a number of separately controlled spray-nozzle groups. The electricarc furnace 11 delivers metal at a uniform rate controlled by automatic tilting devices, and comprises a water-cooled lintel 23 above the discharge spout 10, which tends to freeze slag on the surface of the metal to form a floating slag dam 11c. Slag-forming material such as lime or dead burned dolomite and lime may be added. Sheet metal 25 and asbestos cloth 24 shields the molten metal discharged from the furnace, and fuel gas is burned by a burner 26 around the stream to reduce oxidation. The tun-dish 12 comprises baffles 35 and a cover 29 and the discharge therefrom to the mould is shielded by panels 27, a burner 28 being spaced along both sides and the top of the discharge stream. The dish is removably mounted on an adjustable frame in a carriage 36, Fig. 4, and may be tilted on a shaft 40 by a reversible motor 53, and moved on beams 45 by a motor 42 driving screw-threaded shafts engaging threaded portions secured to sliding pillowblocks supporting the trunnion bearings 41. The carriage is movable laterally by a motor 60 and a tie rod 61. The mould, Figs. 6, 7, comprises a liner 70 and a cooling water passageway 86 opening via a weir 85 into a chamber 73 which receives cooling water through pipes 76. A top plate 98a partly covers the mould opening, Fig. 4. The atmosphere in the upper portion of the mould is controlled to reduce oxidation, a lubricant, e.g. castor oil, being delivered through feed pipes 88 and a hydrocarbon gas such as C 2 H 2  being introduced through a pipe 89. A small amount of oxygen may also be added. A burner 99, burning e.g. natural gas, encloses three sides of the stream of metal falling into the mould, to protect it from oxidation and to ensure an absence of oxygen in the gaseous material drawn into the mould by the " pumping action " of the rise and fall in molten-metal level. The casting 15 is supported by a guide system comprising, Figs. 6 and 8, rollers 92 mounted in a vertically-sectionalized support frame 16. Standpipes 96 supply cooling water to jets 97 in conduits 95, the regulation of waterflow rate being accomplished by valves 19, operated in conjunction with the withdrawal mechanism. The guide support system is supported upon the standpipes 96 by spring- loaded tubular members 100 welded to cross beams 104 which may move laterally to the axis of the casting on two sides thereof, the rollers 92 on the other two sides of the casting being carried by spring-loaded beams 105 slidably engaging between the beams 104. Rods 122, 123, indicate the spacing between the beams 104.