| 摘要 |
<p>1461842 Feeder heads for casting moulds BROWN INSULATING SYSTEMS Inc 9 Jan 1974 [24 Jan 1973] 1111/74 Heading B3F [Also in Division C3] Ferrous metal in a feeder cavity 11 of a mould 4 is in a zone in which the transfer of heat laterally and upwardly from the metal is low and takes place mainly through the region of contact between the feeder metal and the metal in the mould cavity 6 because the feeder cavity 11 is defined by a heat insulating liner 12 with a cover (17, not shown) and a bottom 13 having an aperture 15 to the mould cavity 6 to form the region of contact, the cavity-defining material having a conductivity not more than 1 B.t.u./ hr./sq. ft./‹F./in. of thickness; because of the main transfer of heat to the metal in the cavity 6, solidification in the feeder takes place progressively from the region of contact and the metal in the cavity 11 stays liquid longer than in the cavity 6, and after solidification is said to have a substantially flat top with virtually no apertures or voids because of the direction of solidification. The surfaces of the cover (17) and the bottom 13 (the latter if separately formed from the liner 12) facing the feeder cavity 11, may have grooves to provide gas passages from the cavity. The bottom may also be frusto-conical to aid its retention in the sand mould 4 in the flask 1 and obviate the use of pins 14. The feeder may be square instead of circular in cross-section and there may be more than one. The material (see Division C3) of the liner, cover and bottom, comprises foundry sand, silica flour and asbestos fibre with a thermosetting binder. Its physical properties are quoted.</p> |
