GB139817A - Improvements in and relating to method of and apparatus for casting propellers - Google Patents

Abstract

139,817. Thacher Propeller & Foundry Corporation, (Assignees of Thacher, T. O.). Oct. 24, 1918, [Convention date]. Casting processes; cores; guiding flasks; flasks; moulding processes; moulds; patterns.-Relates to casting large propellers, and consists in special methods of casting and moulding, and special patterns, flasks, moulds, cores, and vents, runners, and gates. The inner ends of the flask parts, for forming the built-up sectional mould, are inclined and carry locating-pins 126, Fig. 1, with ends finished to planes intersecting at the boss centre and matching up with the corresponding planes of the flasks for adjacent blades. Further registration is provided for by bolt-holes 130 and lugs 106 perforated to pass a locating pin. The pattern-carrying flasks and plates have inclined end plates to co-operate with the pins 126, and are drilled and lugged to match up with the holes 130 and lugs 106. Each mould part has a sectional core print formed' by a loose piece 126<a>, Fig. 5, that is removed prior to the application of a machined bottom plate 133, also drilled to receive the locating-pin passing through the lugs 106. The mould parts are then inverted for drawing the patterns. Upper and lower parts are assembled and clamped, and the sectional blade parts are located on a machined plate 101, Figs. 11 and 12, lying on the bottom of a shallow pit and provided with holes to secure the proper positioning of the register pins in the lugs 106. The pins 126 mutually locate the flasks adjacent to the boss. The plate 101 has the ribbed construction shown, to reduce weight, and a central aperture to receive a plate carrying a core 137 that is received into the prints formed in the mould parts, and that itself is formed with a print for the taper boss core 138. Before this core and the upper core 139 are inserted, the partings of the mould are washed with slurry to prevent the formation of fins. Sprue sticks are placed in the gates and risers 140 formed in the upper mould parts, and the whole is bedded in sand, together with gate frames 142, 143, Fig. 11. Metal is poured into central compartments formed in the frames 142 and passes at the bottom by rising gates 147 into side compartments 144 and thence through the gates 140 into the mould. Slag is trapped by the central compartments. The propeller is cast with its blades sloping downwardly, so that the tips are formed first and the boss last, metal finally rising into the basin 145 to maintain a head during setting.