Patent GB-821189-A (GB)
Title: Pallet loading machine
IPC: B65G57/00
Filed: 1957-08-20
Abstract: 821,189. Pallet loading machines. MATHEWS CONVEYER CO. Ltd. Aug. 20, 1957 [Aug. 20, 1956], No. 26198/57. Class 94(1).  A pallet loading machine having a shaft with a lift therein for raising and lowering a pallet and with means for depositing a layer of articles upon the pallet when in a raised position, comprises sensing means for sensing the height of the layer of articles in the shaft, said means, when the articles are at a predetermined level, being operative to move closing-in guides into pressure engagement with the sides of the articles to compact and align the layer of articles. Assembling cartons on pallets.- The pallet loading machine, adapted to handle cartons advanced on an infeed conveyer 16 either singly or in pairs, is gravity fed by a conveyer 10 to a metering position 12 serving to conduct cartons at a controlled rate. An acceleration roller 14, at the discharge end of the metering conveyer 12, accelerates the cartons on to the conveyer 16 to space them out. On the conveyer 16 a carton turning device 18 may operate to selectively turn cartons in accordance with a desired pattern of cartons to be placed on the pallets. The conveyer 16 carries the cartons past a photocell light beam 19 in a counting circuit and thence onwards until they abut against a raised stop 22. More cartons then accumulate behind the first pair of cartons, the assembled cartons being squeezed by a spring loaded guide 26 against a side wall 24. When the photo-electric cell unit has counted a requisite number of cartons it causes (a) a shaft 102 to rotate to lower a stop paddle 124 in front of the leading edge of the first pair of cartons accumulated behind the stop 22, (b) a pressure operated piston to act on the stop paddle 124 with just sufficient pressure to make it tend to move towards the pallet lift without actually doing so, and (c) the carton stop 22 to be lowered. Lowering of the stop 22 permits the feed conveyer 16 to push the assembled cartons on towards the pallet lift, the resistance of the stop paddle 124 being only sufficient to maintain it in contact with the leading carton. As additional force is needed to push the cartons on to the apron 28 over the pallet lift shaft, the last carton moving away from the path of light 19 of the photo-electric cell causes a pusher paddle 126 to move forwardly and downwardly from a raised position by means of a drive motor D-3 acting through chains, the motion being at a rate sufficient for the pusher paddle 126 to catch up with the moving cartons and transfer them from the conveyer 16 to the apron 28. As the pusher paddle 126 passes the stop 22 it strikes a limit switch to cause the stop 22 to rise and prevent any following cartons from passing on to the apron 28. When the cartons are fully on the apron 28 a cam on the pusher paddle assembly operates another limit switch to cause the shaft 102 to turn 90 degrees to raise the pusher and stop paddles to a vertical position and to drive these paddles back to their original position, the paddles being vertical so that they shall be clear of any cartons that may have accumulated on the conveyer 16 against the stop 22. The apron 28 is then indexed to move the transferred cartons to a position in which a clear space is provided on the apron for the reception of a subsequent group of cartons. When the apron is full it is retracted beneath the side wall 24 which strips the cartons from the apron allowing them to drop on to the pallet 320 disposed in the shaft below the apron. Closing in guides.-Two side guides 30, 32 and an end guide 34, Fig. 1, operate beneath the apron 28 that is in the same horizontal plane as the conveyer surface 16 to compact the tiers of cartons 18 as they are deposited on the descending pallet. The guides 30, 32, can swing inwardly on limbs 252, 254, and are operated by piston means fed through a reversing valve. Spring means acting on the reversing valve establishes a normally open position of the closing-in guides 30, 32. Energisation of a solenoid coil 284, Fig. 13 (not shown), actuates the reversing valve to cause the piston to drive the guides 30, 32, to their carton engaging position as shown in broken lines. As the loaded apron 28 retracts beneath the stripper wall 24, the wall 24 not only strips the cartons from the apron 28 and deposits them on the pallet but it also serves to square up and align the carton assembly. Hence only a single front closing-in guide 34 need be employed in a direction transverse to the action of the side closing-in guides 30, 32. The front closing- in guide 34 is mounted on guide rods 302, 304, slidable in journals 306, 308, and acted on by piston means 303 acting through a cranked arm 318, 320. A solenoid operated four way reversing valve actuates the piston means 303. Control of the lift and closing-in guide means is by a tracking arm assembly 29, Fig. 1, on the downstream edge of the apron 28. This assembly includes a roller 362, Figs. 17 and 18, which is normally in contact with the upper surface of the apron 28, the roller 362 being on an arm 360 secured to a bevel gear 356 rotatable on a stud 354 and capable of turning a second bevel gear 374 having an elongated hub portion 376 carrying a tracking arm 378 with a cylindrical weighted element 380 at its end. The tracking arm 378 is of length sufficient to extend into the lift shaft when in the position shown in broken lines in Fig. 18. The elongated hub portion 376 also carries a pair of cams 382, 384, that can engage limit switches LS13 and LS14. When the apron 28 is below the roller 362 the meshing gears 356 and 374 hold the tracking arm 378 in its upright position. When the apron 28 is retracted the roller 362 no longer supports the arm 378 and the weight 380 causes the arm to fall down on to the upper surface of the cartons on the lift and cause the limit switch LS13 to start the descent of the lift. As the lift descends, the tracking arm 378 follows the cartons down and eventually, at a predetermined level of the cartons, the limit switch LS13 is again actuated to halt the descent of the lift whilst the other limit switch LS14 initiates the action of the closing- in guides 30, 32, 34. Guide 34 is adapted to function after the guides 30, 32, have closed on the cartons. A timing relay determines the the period of action of these closing-in guides. Suitable lock out relays are employed to retain the respective circuits in open position upon raising of the tracking arm 378 by the apron 28 as it moves back into a position over the lift shaft. Specifications 811,353 and 811,354 are referred to.