| 摘要 |
Apparatus and process of manufacture for forming a generally cylindrical shell having an interior surface, an opened end with a first internal diameter, a generally closed opposite end, a first internal portion intermediate the ends with a second internal diameter larger than the first internal diameter, and a second internal portion intermediate the first internal portion and the closed end with a third internal diameter larger than the second internal diameter, wherein such apparatus and process of manufacture include a mandrel having an outer surface for forming the interior surface of the shell and having an expandable and contractable intermediate portion, the mandrel intermediate portion expandable outwardly to form its second internal portion and upon the shell being formed the mandrel intermediate portion contractable inwardly sufficiently to permit the mandrel to be moved relatively away from the formed shell through the open end to permit the formed shell and the mandrel to be separated.
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