Patent GB-1399646-A (GB)
Title: Manufacture of envelopes
IPC: B31B23/00
Filed: 1973-06-07
Abstract: 1399646 Making envelopes, cutting apparatus DAVID CARLAW (ENGS) Ltd 31 Oct 1973 [8 Dec 1972 7 June 1973] 56649/72 and 27220/73 Headings B5D and B4B [Also in Division B8] A method of manufacturing envelopes includes the steps of forming spaced elongate cutouts in each edge of a strip A of paper and transversely cutting the strip in a region adjacent one end of each recess to form separate blanks each comprising a front panel to which is attached a back panel, side flaps and a top enveloping sealing flap. The elongate cut-outs are formed by a pair of rotatable chopping blades 301, 302 located on each side of the strip, and pairs of disc cutters 401, 402. The chopping blades form cut-outs B in the edges of the strip A and the disc cutters remove the tongues C formed between the cut-outs B. The chopping blades of each pair are relatively angularly adjustable. The disc cutters 401 are mounted on a pivoted lever 403, and are moved into and out of their operative positions by an eccentric 407 acting on the lever 403 through a connecting-rod 406. The portion of the stroke of the cutters 401 during which they are operative may be altered by adjusting the length of the connecting-rod 406. The distances between successive cuts formed by each of the chopping blades 301, 302 are adjustable by varying the speed of strip feed rollers 5 relative to the speed of the chopping blades 301, 302. Such a variation, which produces blanks of a different size, may be effected by a change gear. The strip is cut transversely by a rotatable knife 602 and a fixed knife 603. The blanks so formed have their back panels folded on to their front panels, E, upon being passed into a blind spur channel (703, Fig. 1B) whose effective length is adjustable. The side flaps are then pre-folded, F, and unfolded, G, by a folding plough arrangement (801, 802, 901, Fig. 1B). After the side flaps have been gummed, H, by a gumming roller (1001, Fig. 1C), the side flaps are once more folded over on to the back panel of the envelope, I, by a further plough arrangement (801, 802, Fig. 1C). The blanks are next sucked on to the circumference of rotating coaxial discs (1201, Fig. 1C) and are carried thereby into the nip between discs (1202, Fig. 1C) and a roller (1203, Fig. 1C). The discs (1202) which are coaxial with the discs (1201), are rotated more slowly than the discs (1201) to effect shingling of the blanks J, so that a gumming roller (1001, Fig. 1D) can gum the envelope top flaps. After this gumming operation the speed of the blanks is increased to prevent their gummed areas from sticking together, and the folded blanks are completely separated from each other after passing through a drying zone (14, Fig. 1D). The top flaps of the envelope are then folded over, L, by passing the envelope into a blind spur channel (703, Fig. 1D) whose effective length is adjustable, and the completed envelopes are stacked on their edges by rotatable discs having involute slots (1601, Fig. 1D) into which the envelopes are fed and later withdrawn by abutment against ramps (1603, Fig. 1D). Various components of the apparatus are laterally adjustable to accommodate strips of different widths.