Patent GB-795978-A (GB)
Title: Jet damping and metal purifying device for ingot or other moulds
IPC: B22D7/00
Filed: 1955-11-17
Abstract: 795,978. Casting-processes. DAUSSAN, H. J. Nov. 17, 1955 [Nov. 18, 1954; Feb. 8, 1955], No. 32912/55. Class 83 (1). A pouring-jet-damping and metal-purifying device comprises the combination of a float whose cross-sectional area is capable of being varied, and expanding means acting on said float to tend to increase said sectional area. The float 1, Figs. 1, 2, comprises a spiral-wound strip 2 to which a corrugated strip 3 is attached. The strips, which may themselves be corrugated, may be of paper impregnated with a fire-proofing substance such as sodium silicate, or of compressed vegetable, animal or synthetic fibres, asbestos, magnesia, or mixtures thereof, and incorporate silicones or synthetic rubber. A spiral spring 5, e.g. of steel or fireproofed cane, expands the float into engagement with the walls of the mould as it rises on top of the cast metal. The float is preferably made of destructible materials which form a heatinsulating mass 7 in the dead-head b. The spring may be of the form shown in Fig. 3, with flexible appendices 10 to produce a square expansion in a float for use in a square-section mould, or the number of appendices may be increased for use in a mould of polygonal section having more than four sides. Alternatively, four springs may be superposed and oriented in such manner that the required cross-section is obtained in the course of expansion of the float. The float may be spaced from the mould wall by fireproofed distance pieces clipped on to its periphery. In a further embodiment, Fig. 7, the float comprises four elements 1b-1e of e.g. wood, sawdust or shavings fireproofed by silicate of soda, or a silico-aluminous or magnesium product, with passages 17 for the passage of gases from the melt, and recesses 16, supported by a resilient frame comprising spring-loaded telescopic tubes 18, 19. The device is held in its contracted position by a band 14, or clips 15, or both, until these are destroyed by the molten metal. The float may be spaced from the mould wall by projections on its periphery. In a further embodiment, Fig. 9, the float 1f is similar to that shown in Fig. 1. A refractory conical member 23 is resiliently secured to the float, and as the assembly rises on top of the melt, the member 23 enters the central opening of the float in the manner of a wedge so as to keep the periphery of the float in engagement with the mould wall. In a further modification, Fig. 12, the expansion of the float 1h is controlled as it rises by a tube 33, e.g. of a paper band wound upon itself and impregnated with sodium silicate. In a further modification, Figs. 13, 14, the strip-wound float B is grooved along planes ZZ and YY and may comprise an expanding device as previously referred to or, as shown, resilient arches 45, 46. As the device rises with the melt, the action of the molten metal causes the float to break along the weakened planes and the arches cause the four portions to bear against the mould wall. If there is more than one pouring aperture, several floats may be disposed side by side, each corresponding to one pouring aperture, or a single float may comprise more than one pair of weakening grooves disposed in planes which, in each pair, intersect along a line positioned in vertical alignment with the corresponding pouring aperture.