Patent GB-828930-A (GB)
Title: Flap folding apparatus and method
IPC: B31B50/58
Filed: 1956-09-25
Abstract: 828,930. Making cartons. LABOMBABDE, R. A. Sept. 25, 1956 [May 8, 1956], No. 29260/56. Class 18. [Also in Group XVI] In a box making machine folding apparatus for overfolding the leading flaps of each of a plurality of flat box blanks advancing individually along a path through a folding machine comprises a rigid folding finger supported at its upper end for oscillation of its lower end in the direction of the path of the blanks, the finger having a trailing hooked portion normally preventing a notch in the path of the leading edge of the flap to be folded and being spring-biased to oppose oscillation during folding, and a stop for positively stopping the finger at a predetermined point of oscillation. As shown, a flat article to be folded, e.g. a box blank 20, is fed from a magazine 48 in a zone 61 to the entrance nip of opposed pairs of belt carriers 52, 53 and 72, 90. The blank is carried by the belts 52, 53 in the folding zone 62 and by the belts 72, 90 in the zones 63 and 64. Extending the full length of the machine are laterally spaced supporting bars such as 70, 71 over which the blank travels. The blank comprises side panels 21, 22, 23 and 24 and a glue lap 25. Cover flaps 26, 27, 28 and 29 are connected to the side panels along a fold line 31 and bottom flaps 32, 33, 34 and 35 are connected to the side panels along a fold line 36. In the zone 61 the flaps 34 and 35 are folded and a tab 38 on the flap 35 is overfolded. To this end flap folding fingers 139 and 216 are provided, the flap 34 being held folded by a holding bar 205 and the tab 38 being overfolded and subsequently held down together with the flap 35 by a bar 206. In zone 63 a twisted folding bar 105 folds sections 21 and 22 at right angles to the sections 23 and 24 about the fold line 58 and a bat 106 then opens the blank out again thus ensuring that the resulting collapsed box may fold readily about the line 58. In zone 64 the flaps 32, 33 and tab 37 are folded by fingers 217 and 218 and held down in identical manner to the folding of the flaps 34 and 35 and tab 38. In zone 65 glue is applied to the glue lap 25 from glue pots, the glue lap having been prefolded and then reopened by a device 107. Finally in zone 66 twisted folding bars 101 and 102 fold the panels 21 and 24 respectively about fold lines 59 and 57 to produce a collapsed box for stacking in a zone 67. The flap folding fingers 139 and 216 are mounted from a support 122 carried by brackets 123, 124 depending from a frame piece 125 of the machine. The support is provided with a slot 126 for longitudinal adjustment. Presser means 134 is provided on that side of the longitudinal centre line of the support 122 remote from the flap 34. Presser means 134 includes a plurality of freely revolvable rollers arranged in cages 136. The finger 139 is arranged for upward oscillation about a pivot pin 140 carried by a clamp member 141, the latter being angularly adjustable about a pivot pin 143 on a bracket 144 itself transversely adjustable on the support 122. The finger 139 is biassed downwardly by a coil spring 151. An arcuate stop member 154 is adjustably provided concentric with the pivot axis of the finger 139 on a bearing extending from the clamp member 141. The finger 139 is bent at 163 to form a flap engaging notch 165 and hooked portion 164. Downward rotation of the finger 139 is controlled by a block 176 provided in a recess 177 in the support 70 below the level of the paper line. The block 176 has an inclined face for wedging engagement with the tip 171 of the finger 139. The block is provided with set screws so that it may be adjustably positioned in the recess 177. By adjusting the clamp 141 about the pivot point 143 a longer finger 162 may be employed for folding larger flaps. In the event of box blanks having windows in line with the flap to be folded the finger is prevented from dropping through the window by a follower arm fixed to a shaft extending from the pivot 140 and rotatable with the finger 139. The follower arm is adapted to run over that part of the blank not provided with a window thus holding the finger 139 up until the whole blank has passed thereby, Fig. 11 (not shown). After the flap 34 has been folded the blank advances under hold-down bar 205 to the second folding finger 216 which is arranged to operate in the same fashion as the finger 139. The presser rollers adjacent the finger 216 corresponding to those in the cages 136 for the finger 139 are arranged on that side of the support 122 remote from the finger 216. A resilient holddown strip 198 is also provided adjacent each folding finger, each strip being supported by rods 201 adjustably mounted in the slot 126 of support 122. The tab overfolding bar 206 includes an upwardly curved portion 207 to engage and fold the tab 38 forwardly on the back-folded flap portion. The folding unit 121 in the zone 64 is similar to that in the zone 62. A folding finger as 139 may be modified by the provision of an aperture 240 for a screw 241, Fig. 10A, the screw supporting an angular filler piece 242 having an inclined face 243 for use where the flaps have an oblique leading edge. In an alternative form the finger 249 may be bent as shown in Fig. 14 at 260 so as to prevent downward bowing of a flap being folded. In this embodiment, the block 265 is arranged to engage the notched portion 259 of the finger.