Patent GB-1388151-A (GB)
Title: Sheet folding amchines
IPC: B29C53/04
Filed: 1972-03-24
Abstract: 1388151 Folding sheet material FMC CORP 24 March 1972 [7 May 1971] 14058/72 Heading B8R A method of directionally controlling the leading end portion of a moving double-wall sheet having a closed leading edge comprises the steps of reforming said leading edge by advancing one of said walls relative to the other of said walls in the direction of movement of the sheet, the relatively retarded wall pulling said leading end portion of the sheet as a whole toward the side which includes the retarded wall. A bag blank B, Fig. 4, is advanced with a pre-folded or sealed edge foremost by a conveyer 50, Figs. 2 and 4, to the first folding station PF1, Figs. 2, 4 and 15, of a primary folder PF, with its centre aligned with lane B, Fig. 15. The folding station comprises a pair of nip rollers 70, 74 and a perforated air tube Al from which air jets are directed towards the nip of the rollers when the line along which the bag is to be transversely folded passes between the tube and the nip. The trailing edge of the blank is sensed by a scanning means comprising a photoelectric detector S1 co-operating with a reflecting surface 76, which detector opens valves V1, V2, Fig. 6, to supply air respectively to the two halves of the tube, which are separated by a block at 103. The air is supplied at a moment determined by the position of the detector, which is adjustable in feed direction, and by an electrical delay mechanism. The blank is fed over a turning roller 56 against a segment of which it is passed by turning belts 70, which move slightly faster than the roller so as to advance the upper wall of the blank relative to the lower wall, which imparts to the leading edge of the blank to move downwards in contact with supporting belts 71 rather than to bend into the nip between the rollers 70, 74. When the air jets issue, the fold line of the blank is blown into the nip, and the rollers 70 74 fold the blank and advance it on to a conveyer 101. If it is derived to render the station PF1 inoperative while feeding the blank along the same part, the rollers 70, 74 are moved apart and low-pressure jets are blown as the leading edge arrives between the tube and the nipso that the blank is fed unfolded between the rollers 70, 74. The folded or unfolded blank is advanced by the conveyer 101 to a second and similar folding station PF2, where a or a further transverse fold is applied, or which may be similarly rendered inoperative. In the case of a particular blank, one or both of the stations will be operative. The station PF2 is actuated by a similar detector S3. In the case of blanks of less width, two blanks can be advanced side by side along lanes A and C, in which case the detectors S1, S3 are moved into alignment with lane A to supply air to one half of the air tubes A1, A2, while the directors S2, S4 control the air supply to the other half. The once or twice folded blank is fed from the station PF2 by conveyers 144, 200 up against stops 207, Figs. 2 and 3, in a secondary folder SF, having three folding stations SF1, SF2, SF3, Figs. 3 and 9, aligned with lanes C, B, A respectively, and a further folding station SF4. The station SF2 comprises nip rollers 189 and an air tube A4 controlled by a valve V6 and detector S6, also a creasing rod 210 to assist in the folding of thick blanks. The folded blank is fed downwards on to a conveyer 220. In two-lane use, stations SF1  and SF3 are operable. The conveyer 220 advances the blank to the station SF4, comprising rollers 191, Fig. 10, where a further fold may be made, followed by delivery to a conveyer 240. The folds made by the folders PF, SF are perpendicular to each other. If the station SF4 is rendered inoperative, the blank may be fed on to an exit conveyer 236, or, by the removal of the downstream roller 191, fall on to the conveyer 240. The folder PF can be used alone, either by removal of the folder SF, or by retraction of the stops 207, when the blank is delivered by the conveyer 200. If the folder SF is not present, then in the case of relatively flexible blanks, it may be necessary to provide a corrugator roll assembly comprising a plurality of relatively staggered upper and lower wheels with some vertical overlap to provide temporary corrugations in the blank to avoid collapse during ejection into a stacking shoot (Figs. 23 and 24, not shown). If blanks entering the station PF1 are seen to be faulty, detectors S1, S2 are de-activated, and the blanks pass down the belts 71, Fig. 2, to the floor or to a reject conveyer. Specification 1,388,152 and 1,388,153 are referred to.