Patent GB-896541-A (GB)
Title: Apparatus for feeding sheet material
IPC: B65H1/30
Filed: 1959-10-06
Abstract: 896,541. Feeding sheets. FMC CORPORATION. Oct. 6, 1959 [Oct. 7, 1958], No. 33810/59. Class 100(1) Sheet material, such as cardboard, is fed to a machine for staying box blanks from a supply stack which, on exhaustion, is replaced by another without interruption of the machine operation. The sheets may be rectangular and cornernotched, and the stays are applied to form box blanks as described in Specification 826,179. Pile tables: Sheets b, such as box blanks, are placed in a stack sb on a tray 20 which is elevated by projections 22 on pairs of endless chains 21 driven intermittently through worm gearing 28, 29, by a ratchet which is operated by a pawl 32 on an arm 51 which is pivoted to an oscillatable arm 49. The arm 49 is oscillated by a cam 47 on a drive shaft 46 which rotates once each machine cycle. Each operation of the pawl 32 is sufficient to raise the stack of sheets corresponding to the thickness of several sheets. The height of the stack is controlled by a sensing means comprising a switch 100, Fig. 5, disposed below one of a pair of arms 58 which support a floating gate 55, 56, which is rocked into engagement with the top sheet of the stack prior to the removal of that sheet. When the stack is too low, the arm 58 opens the switch 100, a magnet 102 is de-energized so that it has no effect on a metal block 103 secured to the actuating arm 49 of the pawl 32. However, when the stack is too high, the switch 100 is closed, the magnet 102 holds the block 103, and the arm 49 is held so that it cannot follow the movements of the cam 47. The floating gate 55, 56 is associated with oscillating suckers 63 and the members 55, 56, between which each separated sheet is passed, are set apart a distance which is less than the thickness of two sheets. The tray 20 is tilted, as shown in Fig. 2A, and the stack of sheets is controlled by adjustable guides 52. As shown in Fig. 4A, to enable the suckers 63 to continue separation of sheets without interruption when a new stack is introduced, a second stack on a tray 20b is arranged immediately below the expiring stack on tray 20a. When all the sheets have been removed from the upper tray 20a, the latter is moved upwardly by the chains 21 until it is engaged over latches 110 for subsequent removal by the operator. To enable the suckers 63 to operate immediately on the new stack, the tray 20a is notched as shown in Fig. 5, to allow the suckers to pass through it to engage the top sheet on the new stack. Separators: Sheets b are separated from the top of a stack sb by the co-operation of the suckers 63 and floating gate 55, 56, Figs. 2A and 5. The members 55, 56 are carried by a pair of pivoted arms 58 which are urged upwardly by springs, and the sheets are separated by the oscillating suckers to pass between projections 55a, 56a on the members 55, 56 which are spaced apart a distance which is less than the thickness of two sheets. The projection 55a is first adapted to rest on the top of the sheet stack, the suckers insert the top sheet through the gate 55, 56, and then the suckers and gate are raised together to feed the sheet between a pair of feed rollers 81, 82. The suckers 63 are adjustable on a hollow suction tube 59 carried by arms 80 on a shaft 69 which is rocked from the shaft 46 through a cam 77 and arm 75. The lower member 56 of the gate is connected by pull-rods 71 to bell-cranks 68 pivoted about the shaft 69 by cams. 66 pn the shaft 46, and the arms 58 have channel portions 58a engaged by arms 60 secured to the suction tube 59. A valve 95 controlling the suction at the suckers 63 is operated by the arm 75. The feed rollers 81, 82 are continuously driven by a chain 86, and feed the sheets to a machine, for staying box blanks. In a modification, the suckers 63 are each resiliently mounted so that they are capable of engaging sheets which are not perfectly horizontal, and provision is made for lifting the top feed roller 81 so that the feed of the sheet received from the suckers can be timed accurately to suit the operation of the machine. Furthermore, the arms 60, secured to the suction tube 59, engage cam tracks on the arms 58 whereby the suction cups follow a triangular path.