| 摘要 |
<p>752,221. Heating plastics electrically. TUBOPHANE. Jan. 21, 1954, No. 1859/54. Class 39(3). [Also in Groups V and VIII] A tube made from plastic material is placed on a mandrel 2 so that it projects by an amount 9, Fig. 2, which is pressed down by a heated cup-shaped tool 15 to form a rudimentary tube end which, after being cooled to stabilise the material, is brought under an electrode in a high frequency circuit (see Group V). The electrode is shaped according to the required tube end shape, and dielectric loss heating smooths the end of the tube and fuses the material tobether. The electrode may incorporate a condenser, Fig. 10, to intensify the heating effect, which may comprise thin layers 27 of brass and cellulose acetate retained by a screwed member 25 in a. structure screwed on a base 18 provided with plugs 36 for insertion. into the holes 37 of a metal plate connected to a source of high frequency current, enabling easy replacement of the condenser. In an installation as shown in Fig. 11 a rotatable table 1 brings mandrels carrying tubes underneath a shaping tool 15, heated by electrical resistance and carried by a sliding arm which is lowered by the depression of a pedal 11. The table is then rotated to a position when electrodes 26 are lowered on the preformed tube end by further depression of the pedal.</p> |
