| 摘要 |
An inflatable crown roll for a rolling mill is made entirely from castings and has a cavity of very small radial dimension. In one embodiment the arbor is cast in the usual way. Its surface bounding the cavity is coated with a refractory composition that will disintegrate after being heated to casting temperature. A sand mold for the sleeve is then formed around a pattern, the pattern is removed, the cast arbor is positioned vertically in the sleeve mold and the sleeve is cast around the arbor. The sleeve metal temperature is regulated so that the sleeve fuses to the arbor at its necks. The disintegrated coating is flushed out through drill holes in the sleeve by fluid, leaving a cavity between arbor and sleeve. A sleeve with a composition of metal on its working face different from that of its neck portion may be cast by positioning gates with shut-off valves and risers at appropriate positions in the sleeve mold. Another embodiment of the sleeve is cast in a vertical mold provided with a sand core on a vertical support, the core having an external surface which bounds the cavity. After the casting solidifies the core and support are disintegrated and removed. The cast sleeve is then turned end-for-end and its interior is filled with molten metal of a composition which will shrink but will not fuse with the sleeve material. The shrinkage provides the cavity between sleeve and core.
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