Patent GB-784015-A (GB)
Title: Improvements in or relating to apparatus for folding trailing flaps
IPC: B31B50/54
Filed: 1955-08-04
Abstract: 784,015. Folding Saps of box, envelope &c. blanks. LABOMBARDE, R. A. Aug. 4, 1955 [Aug 9, 1954], No. 22432/55. Class 100(1) Mechanism for folding a trailing flap of a box, envelope, &c., blank while the blank is advancing continuously at constant speed through a folding machine comprises an endless chain having an upper stretch advancing parallel to but under the article path at a speed 'less than that of the article and a flap-folding finger mounted on the chain so that a portion thereof extends above the path of the article, as the finger approaches the upper stretch of the chain after the latter has advanced along a part-circular path at one end, the end of the finger travelling at a greater speed than the carrier and the article along this path so as to fold the flap and thereafter travelling at the carrier speed so that the blank draws ahead of it. As shown in Fig. 1, one or more flap-folding fingers 37 are fixed to links of an endless chain 28, the upper run 30 of which is situated below the path of and travels at a lower speed than the blanks 22. The chain 28 at its ends passes over driven sprockets 34, 35, and as the finger 37 moves along the curved stretch 31 at sprockets 34 its end 38 moves at a greater speed than the chain 28 and the blank 22 due to its greater distance from the shaft 32 and thus folds a trailing flap 26 about a line of articulation 27 into a vertical position. Along the horizontal stretch 30 the finger 37 travels at the chain speed and the blanks move away therefrom, thus permitting the finger to pass downwardly around the sprocket 35. In a modified construction, Fig. 3, for folding a trailing flap flat on to the blank proper, the blanks 43 are fed by pairs of upper and lower conveyer belts 42, 44 spaced transversely to leave the trailing flap 45 free. Beneath the belts 42 is an endless chain 48 having rollers 50, 51 at the joints of the links 49. At one end the chain 48 passes over a driven sprocket 52 and at the other end it passes around the curved surface 56 of a smooth track 55 supporting the rollers 50, 51 and. then along an upper stretch 54. The drive is such that the speed of the chain along the stretch 54 is less than that of the articles. An external guide track 155 may be provided for the rollers 50, 51 or for additional rollers 156 on the chain. The distance of the track 55 from the sprocket 52 may be adjusted and the sprocket 52, track 55 and chain 48 may be adjusted laterally of the machine as a unit. Rigidly attached to one or more links of the chain are one or more flap-folding fingers 70 each bent as shown relatively to its base 71. As in the first construction, the finger bends over the trailing flap 45 of a blank 43 about a line of articulation 46 and subsequently is left behind by the blank which passes under a hold-down bar 83, Fig. 7 (not shown); due to its shape, the finger folds the flap flat on to the blank proper. Above the belts 42, 44 is a driven shaft 77 carrying a rigid arm 75 to which is attached a resilient hold-down member 80 the end 81 of which is adapted, while moving at the speed of the blank, to engage each blank in turn just in advance of the articulation line 46 to keep the blank flat during the initial part of the flap-folding operation and then to move rapidly upwardly clear of the flap during the completion of the fold. The shaft 77 is driven by inter-engaging oval gears to achieve the required cyclical variation of speed. The fingers may be fixed to the chain by means permitting of their release if subjected to abnormal stress. Such means comprise a tongue 92, Fig. 11, depending from a base 93 on a folding finger 91, the tongue fitting into a correspondingly-shaped groove 94 in a bracket 95 carried on a link 49. At least one ball socket 96 is provided in the tongue engaged by a spring-pressed ball 97 mounted in the bracket 95 so as normally to hold the finger in a fixed position in relation to the link. If a jam occurs, the socket 96 is released and the finger drops out of the machine.