Patent GB-1466163-A (GB)
Title: Manufacture of integral metal shafts
IPC: H02K15/00
Filed: 1974-04-18
Abstract: 1466163 Welding by fusion AUGUST-THYSSEN-HUTTE AG 18 April 1974 [19 April 1973 24 Dec 1973] 17048/74 Heading B3R [Also in Division C7] Rotary shafts, particularly turbine or electric generator shafts, comprise a plurality of layers of metal deposited on a core, each layer comprising juxtaposed, and preferably overlapping, weld beads. The layers may be effected by using several welding heads, in line abreast or ahead, or groups of heads, simultaneously. Welding may be plasma arc or, as shown, submerged arc welding. Apparatus for helical bead layer deposition comprises core-end supports 4, a core-rotating drive (14), and an automatically controlled longitudinally travelling support 6 carrying, by way of a boom 7, a welding head to which is fed consumable electrode 13 from a reel 12 and current from a source 11. Flux powder is fed, through a tube 10, from a hopper 9. Alternatively, the workpiece may be longitudinally moved instead of the head. In a described operation, whilst layers 16, 17  of helical weld beads 15 are deposited, the main body of the already formed workpiece is independently heated, as by radiant or convective heating, to a temperature T H  (200-650‹ C., preferably at least 500‹ C.) and pre- and postcooling coolant, e.g. air or water, is applied locally to the workpiece surface at 18, 19 respectively to reduce the workpiece temperature near its surface to a pre-cooling temperature T V  and a quenching temperature T A  (300‹ C. or lower, e.g. 200‹ C.), a welding temperature T S  being reached between T V  and T A  To produce a bainite crystalline structure, the quenching temperature T A  should be a little below the martensite point Ms. Metal alloy composition, rate of melting, input of current, and heating and pre-and post-cooling rates are selected, and may be varied throughout the shaft, to suit desired mechanical properties. Control of welding current determines the heat treatment, by molten metal sensible heat, of the metal already deposited. The flux powder may be such as to add metal to the deposited metal. The deposited metal may comprise 0À01-0À10% C 0À05-1À0% Si 0À20-2À50% Mn Up to 5À0% Cr Up to 5À0% Ni Up to 2À0% Mo Up to 1À0% V Up to 0À2% Ta Up to 0À2% Nb Up to 0À50% Ti Up to 1À5% Cu Up to 0À5% Al Up to 0À5% Se Up to 0À5% Zr Balance Fe A core may be formed by longitudinal deposition of layers of beads on a temporary support, e.g. of steel or copper, which is removed prior to rotation of the core and deposition of helical bead layers thereon. The core may be solid or hollow. In example embodiments, in producing a solid cylinder core, several planar layers are deposited on a supporting sheet, the number of beads per layer decreasing progressively so that a body of semicircular cross-section is produced, the support sheet together with an adjacent layer is then removed by cutting, and finally the deposition is repeated on the support provided by the already formed (and turned over) body to produce the cylindrical core. Thereafter the above helical bead deposition is effected under a flux of 14À0% SiO 2  1À0% Fe 1À3% Mn 5À4% CaO 26À0% CaF 2  19À0% Al 2 O 3  2À0% Na 2 O 31À0% MgO using a copper coated consumable electrode consisting of 0À12% C 0À10% Si 1À60% Mn 1À55% Ni 0À65% Mo 0À33% Cr 0À08% Cu Balance Fe to produce a deposited metal of 0À08% C 0À34% Si 1À82% Mn 1À51% Ni 0À63% Mo 0À31% Cr 0À08% Cu Balance Fe, or using a consumable electrode of 0À14% C 0À15% Si 1À82% Mn 1À10% Cr 0À60% Mo 2À55% Ni 0À10% V Balance Fe to produce a deposited metal of 0À09% C 0À38% Si 2À05% Mn 1À02% Cr 0À57% Mo 2À48% Ni 0À09% V Balance Fe.