| 摘要 |
PROBLEM TO BE SOLVED: To produce the article by demolding stably even in the shape of a large undercut by a method in which during demolding, low pressure air is supplied from a vacuum-demolding holes converged near an undercut forming part of help the demolding from the undercut forming part of a molding while the part being warped. SOLUTION: A female mold for thermoforming is composed of a bowl-shaped main cavity 21 and a nearly cylindrical bottom mold 22 to close a through hole 21a. Numbers of vacuum-demolding holes 23 are arranged in the inner surface of the female mold to be converged to a bowl bottom part for forming an undercut. The holes 23, through a hollow passage formed in the bottom mold 22 and a hollow passage formed in a bottom mold base, are made to communicate with an external pressure control mechanism through a control valve, during demolding, and compressed air is supplied, while an undercut forming part is being warped, to help demolding from the undercut forming part.
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