Patent GB-1052051-A (GB)
IPC: B65G61/00
Abstract: 1,052,051. Stacking-machines; suction lifting devices; endless conveyers. WOODFIELD BENNETT Ltd. Jan. 22, 1964 [Jan. 22, 1963]. No. 2723/63. Headings B8A, B8C and B8H. [Also in Division G3] A machine for stacking articles such as bricks includes a pick-up head movable vertically and mounted on a carriage for travel in two horizontal directions at right-angles to each other. the head being rotatable about a vertical axis and capable of tilting about two spaced horizontal axes and all the movements being effected automatically by pre-set controls. The machine may follow a programme on a punched tape, the latter operating hydraulic control valves through an electronic and a relay system. The bricks may be assembled on a series of tables raisable individually to bring selected groups of bricks to the pick-up position. The pick-up head may have two separable portions for dividing a group of bricks into two groups. The vacuum gripping arrangements of the head may be as described in Specification 989,121. General arrangement.-The machine described loads kiln trolleys 67, Fig. 1, and comprises infeed conveyers 101, 102 leading to a pick-up station 4. The pick-up head 3 is supported for vertical movement at fast and creep speeds from a gantry 2 mounted for movement in the two horizontal directions on a frame 8. Pick-up Station, Figs. 6, 7.-The station comprises a series of " tables " (sixteen as shown) for each lane, each table having an endless support belt 49 and being mounted for raising and lowering by pneumatic means 55. Each table supports a single brick. Rails 61 run along opposite sides of the tables and are movable inwards to align the bricks by levers 57 and pneumatic means 60. The rails carry microswitches 62 operated by the bricks to close the pick-up circuit when the desired batch has accumulated. Each table includes means to tilt opposed pairs of tables away from each other to space their bricks during infeed, this taking place while the rails 61 are in their inner position. When the rails 61 are out, the tables return to horizontal and their belts are held by a braking pad 65 rising from beneath, Fig. 8 (not shown). The opposed pairs of tables are capable of separating in the longitudinal direction each pair being mounted on a carriage 45 running on rails 44 and loose linked at 47 to those on each side of it. Pneumatic means 48 operates a tie-rod to pull the tables to the left. Fig. 6, to separate them for pick-up. The pick-up head, Figs. 1, 4, 5.-The carriages bearing the gantry 2 are each driven by leadscrews and individual hydraulic motors. The head is suspended from the gantry by the hydraulic cylinder giving vertical movement and is pivotable through 90 degrees. Two gripper groups 25 are supported on brackets 28 for movement towards and away from each other by pneumatic means 31 along guide tubes 26, 27. The groups are pivotable about the axes of the tube 26 and a pivot 39, Fig. 5, and raisable vertically relative to the upper portion of the head to give a " creep " movement. Controls.-The apparatus is controlled by a punched tape. The horizontal and vertical pick-up movements are all arranged for initial fast and then fine movements. The horizontal movements are each monitored by a device (not illustrated) comprising a rotating castellated disc on the lead-screws interrupting a light beam to produce pulses which are fed to a digital position feedback register converting them to an analogue voltage, the latter being continuously compared with and subtracted from the demanded voltage. When the resulting error reaches a certain value, a signal from a servo amplifier closes a servo valve in the hydraulic drive to decelerate the carriages. At a positioned error of less than a predetermined value a coarse/fine change-over switch puts the carriage position under the control of resolver synchros and the analogues on the fine position registers. Comparison is then made between carriage motor-driven synchros and synchros at the control panel until zero error closes the servo valve to bring the respective carriage to a halt. Hydraulic and electronic controls are stated to be conventional and are not described.