| 摘要 |
A tool for use in manufacture of a hollow article having an internal surface at least part of which is undercut, the tool comprising a plurality of elements having portions together adapted to define a subtantially complete external surface having a configuration corresponding to that required in the internal surface, the elements including first elements and second elements interposed between them, and the arrangement being such that the first element can be withdrawn from the article to leave a space or spaces to permit the second elements subsequently to be moved inwardly to disengage them from the undercut internal surface part and withdrawn from the article.
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