GB1294323A - Improvements in metal casting - Google Patents

Abstract

1294323 Casting-machines; forging screw-threads UNITED KINGDOM ATOMIC ENERGY AUTHORITY 12 March 1970 [26 March 1969] 15958/69 Headings B3F and B3H A method of casting teeth, ribs or screwthreads on a member or on or in a sleeve 17 comprises rotating a core 18 bodily i.e. without any rotation thereof about its own axis, in a locus about the axis A of the sleeve 17, and pouring molten metal between the core 18 and sleeve 17, the movement of the core not being stopped until the casting metal has solidified and hardened. The sleeve 17 is heated by an induction coil 23 and may have longitudinal grooves on its inner surface to produce keying between the cast annulus and the sleeve. After casting is complete, the table 12 and thus the core 18 are lowered by means of a spindle 13 whose thread is such that the lowering also serves to screw the core 18 off the helical teeth produced by the casting. The table 12 is supported on a flange 16 by resilient members 27 which allow slight lateral movements of the table to permit accurate positioning of the core 18 with respect to the casting before lowering of the table is begun. The rotating movement of the core 18 is effected by arms 21, 22 releasably attached to the top of the core and to eccentrics 6, 7 mounted on rotatable spindles 2, 3. The rotating movement serves to swage the tooth tips so that no final machining of the cast article is necessary. Improved swaging is obtained by slightly increasing the common throw of the eccentrics during cooling of the metal through the plastic state.