| 摘要 |
<p>790,242. Dielectric heating. RADIO HEATERS, Ltd. June 15, 1956 [May 31, 1955], No. 15621/55. Class 39(3) High frequency dielectric heating equipment for welding plastic sheet material comprises an electrode 1 mounted on an insulating block 2 secured to a plunger 4 which is adjustably mounted on a block 6. The block 6 is pivoted to a beam 9 which is itself pivoted at 10, an operating device, e.g. a foot pedal or pneumatic ram, being connected at 11 to the beam for movement of the electrode 1 towards or away from the work table. The downward movement of the electrode is limited by a stop member in the form of a cam which is adjustable by a handle 14 provided with a graduated disc 15 for setting the cam to a pre-determined position. When the electrode 1 has been replaced by another of different thickness, a plastic pattern pieces are placed on the work table, the plunger 4 of the latter electrode is freed and the electrode allowed to rest on the plastic pieces. After turning the cam and graduated disc to a reference point corresponding to the angular position of the cam which gives the highest limiting position for the beam 9, the beam is pivoted such that it rests on the cam and the plunger 4 is clamped to the block 6, the downward movement of the electrode now being limited to the point where it just reaches the surface of the work material. If no limit is to be set on the extent to which the electrode will sink through the material during the weld, the cam is turned to the position which gives the lowest limiting position for the beam. If a limit is to be set to the depth of the sink, the cam is set to an appropriate intermediate position.</p> |
