composite ultraschallsonotrode, particularly adapted for welding of halbstarrem polystyrene and molded cellulose

摘要

PCT No. PCT/FR89/00005 Sec. 371 Date Sep. 13, 1994 Sec. 102(e) Date Sep. 13, 1994 PCT Filed Feb. 11, 1989 PCT Pub. No. WO90/08028 PCT Pub. Date Jul. 26, 1990.A method for ultrasonically welding a transparent semi-rigid lid onto a molded cellulose egg tray employs a compound sonotrode which includes a holding block and a plurality of individual sonotrodes coupled to the holding block. Each of the individual sonotrodes has a respective welding surface gridded by an array of square-base pyramids. The adjoining pyramids have contiguous angled surfaces that form substantially a 90-degree angle therebetween for effectively welding plastic to cellulose. The welding surfaces preferably have an imprint outline that is rectangular or circular.