摘要 |
<p>The moulding device has a pin placed in a guide tube centred in the mould for the piece, the tube being withdrawn mechanically during injection by device operated by the injected material in a secondary mould. The withdrawal of the guide tube from the pin is brought about by the movement of a mobile punch of constant section moving in a secondary mould and coupled mechanically to the tube. The movement of the punch may be used to control the advance of the injected material into the mould. A long stalk such as is used to hold spectacle frames can be made in one process with a small hole through it to hold a pin without risking the de-centering of the pin due to the moulding pressure.</p> |