GB1262471A - Improvements relating to the fabrication of articles - Google Patents

Abstract

1,262,471. Making strip, pipe, rod or bar; continuous casting; casting processes; composite casting; rolling. NATIONAL RESEARCH DEVELOPMENT CORP. 6 May, 1969 [14 May, 1968; 6 Aug., 1968; 14 Aug., 1968 (2)], Nos. 22870/68, 37536/68, 38931/68 and 38932/68. Headings B3A, B3F and B3M. [Also in Division C7] In a method of making metal pipes, strip, rods or bars, gas-atomized particles of molten metal are sprayed on to a substrate and then hotworked either (a) before or after removal from a non-deformable substrate or (b) after removal from a deformable substrate to form a non-porous metal article. The spraying is carried out under an atmosphere of nitrogen, hydrogen, a flue gas, a blast furnace gas or mixtures thereof. A controlled amount of air or oxygen may be admitted to produce specific characteristics of the metal article being formed. The hot-working is preferably carried out by hot-rolling with a reduction between 10% and 60%, preferably 30%. The thickness of the layer can be up to 0À5 inch, preferably 0À01 to 0À375 inch. The substrate may be coated with a thin film of releasing agent, preferably graphite in oil. Other materials such as lead, metal oxides or fibres may be incorporated by spraying obliquely on to the substrate so that they become incorporated in the deposited layer, the oblique spraying ensuring alignment of fibres. The metals may be elements, alloys or intermetallic compounds and include carbon and alloy steels and nickel, copper or aluminium alloys. Laminates may be produced by combining two or more sprays in succession and include Al/Cu, Cu/Al/Cu, Cu/Fe/Cu, Fe/Cu, Fe/brass, Fe/Al, Al/brass, stainless steel/Fe, Al/Fe and Ni/Fe. Reinforcing or other materials may be inserted between successive layers and then compacted. Making strip.-An apparatus, Fig. 1, for making strip comprises an endless stainless steel band 1 as substrate which is rotated on rolls 2, 3. Molten metal from alined tank 20 passes through orifices 21 (which can be plugged when not in use) to a spray ring L0 where gas from a supply 11 atomizes it into a spray chamber 5 and it falls on to the substrate 1 to form a coherent layer. The walls of the spray chamber have gas curtains 6, 7 to keep them free of metal. The strip is fed direct to rolls 29 which hotwork it, the strip remaining gas-shielded up to the rolls. To produce a flat upper surface on the strip, metal powder may be sprayed on from'a supply 23. The thickness of the deposited layer is monitored by a device 28. Coolant may be sprayed on to the endless band 1 by a spray 32 and the band cleaned in a tank 33. An alternative apparatus, Fig. 4, for making strip, comprises two rings 62 driven by rolls 64 and supported by rolls 66. Metal is sprayed on to the rolls by sprays 61 in a chamber 71 and the layers on the rolls are joined and compacted at 63 to produce a strip 65. Reinforcing material or a patterned stop-weld material may be inserted between the layers at 63 and is fed into the gas shield chamber 74 through an opening 76 (shown plugged). Instead of compacting between the rings as shown the two layers may be removed from the rings and later joined, Fig. 6 (not shown). Instead of rings 62, drums or rolls may be employed. Making rod or bar.-Apparatus as shown in Fig. 4 in which the rings are formed with a profiled groove may be used to form bar of a variety of cross-sectional shapes, Figs. 9 to 15 (not shown), modified sprays being used to direct the metal into the grooves either by rolls, shaped surfaces or electromagnetic fields. A number of bars may be formed simultaneously, Fig. 14 (not shown), which are formed joined by narrow thicknesses of metal and afterwards slit to give single bars. Making pipes,-An apparatus for making pipe continuously, Fig. 3, comprises a rotary spray 43 which deposits metal centrifugally on to the inside of a tube 41 which is reciprocated up and down by means of a stirrup 42. The downward movement is slow followed by a rapid upward movement, the pipe thereby being withdrawn at a substantially constant speed. The tube 41 is linked to an air cooled chamber 50 by a bellows 49. The pipe is hot-worked by internal rolls (not shown) and sawn into lengths by a flying saw. An alternative apparatus, Fig. 7, for making pipe comprises rotating a series of linked mandrels 101 in a spray chamber 94 after which the deposited layer is skew rolled at 98 which causes the internal diameter of the pipe to increase thereby releasing it from the mandrel. The mandrels have tapered ends which screw into each other and this produces a part of the deposited layer of smaller diameter than the main pipe section which is not compacted thus easing the separation of lengths of pipe and the removal of the mandrels.