| 摘要 |
1,090,557. Seaming non-metallic sheet material; strengthening edges. RENCO MARWELL S.r.L. Oct. 4, 1965 [Oct. 16, 1964], No. 41979/65. Heading B5K. Relief piping is obtained on sheets of thermoplastic material by inserting in a channel 5 running parallel to the longitudinal axis of a first electrode 4 a cordlike element 7 of synthetic plastics material having substantially the same thermoplastic characteristics as the sheets and of such thickness as to be held with slight constraint by the lateral edges of the channel 5, placing the sheets of plastics material between the electrode 4 and a second substantially flat electrode 1 towards which the electrode 4 presents its channel 5, and passing high frequency current through the electrodes 1, 4 so that when the electrodes have been moved relatively towards each other the superposed thermoplastic parts are fused into a single mass and the joined sheets are cut immediately beyond the join. In the embodiment shown, the lower electrode 1 is fixed and the upper electrode 4 is movable. One of the edges defining the semicircular-section channel 5 projects more than the other to form a sharp cutting edge 6 to cut the sheets immediately beyond the piping after welding. A sheet of insulating material (not shown) may be placed between the electrode 1 and the thermoplastic sheets to avoid the edge 6 coming into electrical contact with the electrode 1 during or after cutting. The invention is applicable to form a double-wall container by providing piping on the edges of four thermoplastic sheets, Figs. 5 and 6 (both not shown). |
