Patent GB-799700-A (GB)
Title: Improvements in or relating to the manufacture of hollow fluid-conducting members
IPC: B22D11/00
Filed: 1957-03-07
Abstract: 799,700. Making pipes, heat exchangers; casting. REVERE COPPER & BRASS, Inc. March 7, 1957 [March 8, 1956], No. 7677/57. Addition to 784,484. Classes 83 (1) and 83 (2). The invention of the parent Specification is modified in that the elongated members about which the billets are cast are formed of a material which includes, at least to a substantial extent, fibres of fused vitreous material sufficiently fine to be flexible, yet pulverizable to a fine weld-preventing powder when the billet is rolled. Fibres of heat-refractory glass, fused quartz, fused aluminium silicate are suitable, and fibres of fused alumina, magnesia or mixtures thereof, with or without various metal oxides such as titanium-oxide, could be employed. Fibres of particular materials should, however, be used only with metals with which they are compatible at the casting temperature of the metals. The elongated friable members may take various forms such as tapes or strips of sheet woven from yarns of the fused vitreous fibres; braided tubes of the fibres flattened to form double-thickness tapes, Fig. 10, or stuffed with fibres, powdered materials such as talc, magnesia, alumina, bentonite, mica or stuffed with lengths of soapstone, graphite or the like; braided cords, Fig. 20A; paper, cardboard or the like strips formed from matted or felted fibres either singly or superimposed and sewn together, Fig. 23, or held together by yarns braided around the strips, Fig. 20. A loaded paper for use with aluminium is made from a mixture with water of 20 per cent by weight quartz fibres, 25 per cent powdered bentonite and 25 per cent powdered magnesia, and a " pressed board " comprises aluminium-silicate fibres with talc powder and powdered bentonite in various proportions. The billets may be cast in a mould comprising opposed face plates 13, 15, Fig. 4, backed by water jackets 23, 25 and between which is a water-jacketed bottom member 17 and side members, not shown. The mould is opened for the extraction of the billet by unbolting the face plate 15. The lower ends of the elongated friable inserts 45 are bent over to form enlarged lower ends which are held in spaced relation along the middle of the mould beneath a pair of plates 47, 49, the former having a row of spaced notches of the same cross-section as the members 45. At the upper end of the mould the inserts pass between another similar pair of plates 71, 73 and are clamped between bars 78 and plates 83. Alternatively the upper ends of the inserts may be secured by hooks 115, eyebolts 111 and nuts 117, Fig. 12, the eyebolts passing through a cross-bar 103 carried by the mould. Springs may be inserted between the cross-bar and the nuts 117. If the inserts are sufficiently rigid, their upper ends may merely project through the openings between the notched bars. When the inserts are in the form of braided tubes filled with a refractory powder, the lower end of the tube may be cut and each side bent back to form an enlarged portion 177' and a refractory stopper 179 inserted, Fig. 31. A modified form of mould for continuous casting may be used. This comprises an open-top runner box 181, Fig. 32, and a casting chamber 195 defined by a water-cooled ring 189 beneath which is a platform 197, to which the lower ends of the inserts are secured by plates 207 (not shown), 209. The upper ends of the inserts are clamped to bars 78 carried by a bar 223 with ends 225 slidable on vertical rods 227 and urged upwardly by counterweights 233 and cables 229 passing over pulleys 231. In operation, the casting chamber is closed by the platform 197 and the inserts tensioned. As pouring proceeds, the platform descends slowly under the action of a ram 199 until the billet is of the required length.