Patent GB-648797-A (GB)
Title: Improvements in or relating to the manufacture of envelopes
IPC: B31B19/00
Filed: 1948-05-06
Abstract: 648,797. Making envelopes. STRACHAN & HENSHAW, Ltd., and COOK, H. C. May 6, 1948, No. 12519. [Class 94(ii)] In making envelopes of the kind having edges parallel to the edges of the blanks from which they are made, roller mechanism is employed to fold and secure the flaps, with the exception of the seal flaps, while the latter are projecting sideways (Fig. 1, stage A). The direction of travel of the envelopes is then deflected through 90 degrees, whereby they progress through a drying zone (Fig. 1, stage B) with gummed and undried seal flaps trailing, and with the envelopes collocated with each disposed below a preceeding one in overlapping relation with the seal flaps exposed. The direction of travel is then again deflected through 90 degrees, whereby the envelopes progress, with an ordinarily wider dimension leading (Fig. 1, stage C), to delivery means. The blanks are withdrawn successively from the bottom of a stack, supported on an inclined table 1, Fig. 2, by means of a suction roller 3 and a rubber-covered roller 4 which fold over a side flap and feed the blank to racing rollers 6 and 7. The three remaining creases are formed by rollers 12, and gum is applied to the end flap and the non-folded side flap by a roller 17. Draw rolls 23, 24 then forward the blank to mechanism which folds over the gummed side flap. The blank is halted by a stop 27, when a blade 33 moves downward to initiate said fold and a table 26 moves forward to feed the blank between rollers 23 and 37 which complete the formation of the fold. The blank is then forwarded horipontally, when the end flap is folded over by a plough folder 40, the seal flap is gummed by a roller 41 and the completed envelope is carried by quick running tapes 46 to a stop 47. A rotating segment member 49, adapted to deflect the direction of travel through 90 degrees, passes the envelope to a gripper 56, Fig. 3, carried on a fast moving chain 57. The grippers release the envelopes just before they make contact with a slowly rotating stepped wheel 59, the width of the steps being equal to the width of the seal flap gumming. The envelopes are then carried between endless belts 61, 63 underneath a shroud 65 where they are dried (stage B) by infra-red lamps. Alternatively, air currents may be used. The envelopes are then passed to rapidly moving tapes 72 which separate them from the overlapping relation. The leading edges then raise a trigger 74 to rotate a hollow catch-member 76 anticlockwise, and thus release a pawl 77 which descends into engagement with the lower flange of the catch-member. The trigger falls to its normal position when the trailing edges pass it, releasing the pawl which completes a revolution to return to its starting position. The pawl is connected by a linkage adapted to slide members 88 transversely, to project the envelopes between the draw rolls of the delivery stage C. In this stage a plough folder folds down the seal flaps, and the envelopes are finally stacked in the vertical postion on a table by means of a pair of endless belts. Specifications 236,509, 236,718, [both in Class 94(iii)], 351,842, [Group XVI], and 370,674 are referred to in the Provisional Specification.