| 摘要 |
<p>The tube or runner is self-supporting and consists of a physico-chemically homogeneous material based on refractory oxides, esp. >=1 of zirconium silicate, corundum, spinel mullite and ZrO2, and made by melting or as a coating obtd. using a plasma burner. The novelty is that an interchangeable extension, made of a heat- and erosion-resistant ceramic, is placed on the end of the tube and enters (part of) the mould-cavity, the wall of the extension, or bush, being provided with control channels (holes) used as ingates for the molten metal to enter the mould. The channels may be circular with dia. 10-600, pref. 20-80% of the wall thickness, or they can have a polygonal or oval cross-section. Used for casting of aluminium- and magnesium- alloys, esp. cylinders and cylinder heads for cars. The replaceable extension permists the mould to be filled without turbulence and also forms the core in the mould; after casting, it is pressed out, pickled to remove dross and re-used.</p> |
