| 摘要 |
<p>1,009,343. Welding by pressure. SCHWEIZERISCHE INDUSTRIE GESELLSCHAFT. Jan. 10, 1964 [Jan. 11, 1963], No. 1160/64. Heading B3R. [Also in Divisions B5 and H5] An electric heater for welding heat sealable materials such as metal foil and/or thermoplastic sheets comprises a heating element 6 in the form of a metal channel having a U-shaped cross-section, the element being secured between metal bars 1, 2 spaced by insulated bars 4, 5. The element 6 is heated by high current pulses at low voltage supplied through the bars 1, 2, the direction of current flow through the element thus being transverse to its longitudinal direction. In use the upstanding base 6a of the element 6 is pressed against the material to be welded and may remain so after the current has been switched off until it has cooled below the welding temperature. The element 6 may comprise a flat strip soldered or welded to the bars 1, 2, Fig. 2 (not shown), or may be channelshaped with short legs fitting into longitudinal grooves in the bars 1, 2, Fig. 3 (not shown), the bar 5 being omitted in each case. Expansion of the element is taken up by a slight corrugation in the centre zone of its welding face, and a stream of coolant may be passed permanently or intermittently along the rear of the element from its centre outwards. Fig. 4 shows an arrangement wherein the heating element 6 Ýs held by and forms part of a single turn transformer secondary winding 12 surrounding a primary winding 11 mounted on one limb of a U-shaped iron core 10, whose other limb may carry a similar winding-heater arrangement so that two welds may be made simultaneously, Fig. 5 (not shown).</p> |
