| 摘要 |
1,201,162. Seaming non-metallic sheet material. FAM FORSCHUNGS ANSTALT FUR MECHANIK. 8 Nov., 1967 [8 Nov., 1966; 19 May, 1967: 12 June, 1967], No. 50863/67. Heading B5K. Two sheets of plastics material, e.g. polypropylene, are friction welded together by vibrating one of the sheets in a direction parallel to the other whilst holding the two sheets together under pressure, the duration of the welding operation being automatically timed, e.g. by means for stopping the vibration of the one sheet upon increase of sliding resistance between the sheets when the interface of the sheets melts. As shown, an eccentric 6 carried at the end of the shaft of an electric motor (2), Fig. 2 (not shown), turns in a square 7 sliding in a rectangular opening 8 in a welding tool 9 the lower end 92 of which is serrated to grip the upper sheet of a pair to be welded which are positioned on a plate 13 of a base 12. The tool 9 is spring-urged upwardly against a tempered steel ball 25 or cylinder which rests in a hollow 93 in the upper part 91 of the tool 9 and is received in a recess in a piston 16. The tool 9 is lowerable by a lever 14 having an eccentric portion 15 which acts on the piston 16 through a strong helical spring 17. A second lever 18 acts resiliently on a toothed drum 19 co-operating with a plate 20 for advancing the sheets. The working surface of the tool 9 comprises toothed zones 31, Fig. 3, and channels 32 between the zones 31 into which channels plastics material can flow during welding. In a modification (not shown), the perimeter of the working surface of the tool 9 is raised to provide a boss. In operation, the motor (2), Fig. 2 (not shown), is automatically operated through a pusher (22) and switches (23) when the lever 14 is lowered. Initially, the rubbing of the ball 25 against the piston 16 and the tool 9 is such that the part 91 does not move laterally relative to the piston 16. When the resistance of the upper sheet increases due to its adherence to the lower sheet the tool 9 is braked and the part 91 begins to oscillate about the fixed lower part 92 and thus avoids tearing of the upper sheet. |
