GB504822A - Improvements in or relating to toothed gears or like toothed members - Google Patents

Abstract

504,822. Moulding toothed gears. SHELTON, T. Aug. 28, 1937, No. 23603. [Class 87 (ii)] [Also in Group XXIV] Toothed gears a, Fig. 1, having a central rib such as a<1> joining the teeth are produced under pressure from organic thermoplastic or thermo-setting material such as synthetic resin, in a mould comprising two relatively - movable parts, each of which is adapted to form one-half of the gear, the mould parts meeting on the plane of the centre of the face width of the gear. The rib a' may extend the full depth of the tooth in which case the mating gear b is suitably recessed, or there may be a rib on each of the gears extending to substantially half the depth of the teeth. The teeth on the two sides of the rib may be in alignment or staggered and, in the case of a helical gear may be at different angles. Further, they may be of different profile and pitch. The mould, Fig. 3, comprises an upper part d and a lower part located relatively by dowel pins d'. Each mould part has a removable liner portion d<2> or c<2> secured by grub screws d<3>, c<3> and pins d<4>, c<4>. Projections d<5>, c6 on the liners d<2>, c<2> form the spaces for the major portions of the teeth, the rounded corners being formed by recesses d<6>, c<6> in central portions d<7>, c<7>of the mould. The moulded gears may be ejected by plungers e. In the mould, Fig. 4, for producing helical gears, a liner f has slots f<1> at intervals along its periphery to receive radial projections g<1> on die members g divided into circumferential lengths and shaped on their inner faces to form the helical tooth spaces. With this mould, the ejectors e raise both the gear and the die members. If a full depth rib is not required, circumferentially split loose pieces such as g suitably modified in shape may be inserted between the upper and lower mould parts.