| 摘要 |
<p>Device of thermoplastic material for making a perforation in an underlying element made of a plastics material compatible with the first-mentioned plastics material. It is composed of a plate (1) of relatively slight thickness, in one face (2) of which a spiral groove (3) is formed, at the center of which the plate is provided with an opening (1'), the said spiral groove being intended to receive an electric heating wire (19) of which one end is intended to be attached to a first projection (7) carried by the plate, on the side of the face in which the said groove is formed, while its other end is intended to be attached to a second projection (10) similar to the first and situated a certain distance from the latter. Application to the making of branch pipes.</p> |
