GB1409248A - Production of jackets for microfilms - Google Patents

Abstract

1409248 Seaming non-metallic sheet material TWINLOCK Ltd 23 Oct 1972 [15 Nov 1971] 52889/71 Heading B5K [Also in Divisions G2-G3 and B6] A jacket for microfilms comprises two preferably transparent polyester sheets 1, 2 united by spaced parallel ultrasonic weld lines 5 to define open-ended elongate pockets. Webs la, 2a are fed intermittently by a belt feeder 27 and power-driven rollers through at least one antistatic device 16 which eliminates static charge and co-operates with vacuum means for withdrawing dust. Web 2a only is passed through a piercing station 17 comprising punches 18 or hot air jets for forming slots 8 to form pocket openings. At this stage the trailing edge (10) of each slot 8 may be raised or curved and strips portions (14) overlying the pockets may be raised out of the plane of the web 2a by cold forming dies. Pin holes 12 and/or notches 13 may also be formed. The webs then pass through a tensioning device 19 comprising at least one roller 21 for each web to an ultrasonic welding station 22 comprising a work horn 23 that receives mechanical vibrations from a transducer 26 and an anvil 24 in the form of a ridged plate or a shaft with collars or discs. The welded webs are passed through a severing station 28 where individual jackets are cut and the lower margins of the sheets 1, 2 are trimmed back to edge 6. The upper edge 3 of thicker sheet 2 projects beyond the upper edge 7 of sheet 1 to form a top margin 9 that receives an adhesive labelling strip or is etched or lacquered for carrying writing. In a modification, each pocket is defined between adjacent pairs of spaced weld lines.