| 摘要 |
The dummy bar comprises a rod (1), and a detachable head (2) in the form of a cylindrical sleeve whose outer diameter D=(0.99 to 0.998) D1 (the mould cavity internal diameter) in order to allow gas to escape during filling of the mould (3). The wall thickness of the sleeve changes over a length L of 100 to 150 mm in accordance with the equation: delta n=(0.1 to 0.2)+(0.03 to 0.04) Cn, where delta n is the wall thickness at a distance Cn from the end of the sleeve. The thickness at the end is (0.0004 to 0.0025)D1. Molten metal reaching the end of the sleeve freezes without penetrating into the gap, so that sealing of the head to the mould is unnecessary. <IMAGE> |
