Patent GB-1120911-A (GB)
Title: A method and apparatus for positioning successive variable length loads at a strapping station
IPC: B65B13/18
Filed: 1966-06-27
Abstract: 1,120,911. Bundling machines; roller conveyers. SIGNODE CORP. 27 June, 1966 [22 July, 1965], No. 28712/66. Headings B8A and B8C. A machine for strapping loads L1, L2 of differing lengths passed along a conveyer 14 driven by an electric motor M1 incorporates a photo-electric &c. sensing device 62, 64 to switch-on electric impulse emitters 30, 32 supplying impulses to a counter 40 which, when a predetermined number have been received, switches off the motor M1 and, whatever the length of the load L1 less than a predetermined maximum, stops the load correctly in relation to a strapping station SS. Strapping shoots &c. 16 &c. are then activated to apply straps round the load. Operation: maximum length load.-A load L1 of the maximum length the machine can handle having been placed on the conveyer 14, a start switch SB is closed. Mains power MS is thus applied to energize a relay switch RM1, so that contacts of this switch start the motor M1. The load L1 is accordingly traversed along the conveyer 14, until its leading edge interrupts a beam of light falling on to the photo-cell 62. The lamp 64, cell 62, &c. are situated half the length of the maximum length load from the strapping station SS. With the photo-cell 62 no longer operative, an amplifier 66 ceases to function, and releases a relay switch RM2. A solenoid clutch C1 is thus engaged by connection through the switch RM2 with the mains, and drivingly connects the conveyer 14 to a toothedwheel impulse emitter 30. The latter supplies impulses through its switch 34 to a pawl-andratchet stepping device SM1, which steps round a counter wheel 42, acting through a first dwell point 48 to actuate a switch 50 controlling holding relays &c. When a sufficient number of impulses have been received by the impulse counter 40, the switch 50 rides into a second dwell point 48 in the counter wheel 42, and switches off the motor M1. The load L1 is then correctly positioned in the strapping station SS. As the switch 50 rides into the second dwell point 48, it completes a circuit through the contacts of a relay switch RM3, a transfer switch CTS, and the closed contacts of another counter switch 54, to the control 70 of the strap-feed shoot 16. A parallel circuit is likewise completed to the strap-feed shoot 18. Straps 12 are thus applied to the load L1 in regions 12a adjacent its ends. Operation: less than maximum length load.- If the load is a little, but not greatly, less than the maximum load length, when its trailing edge passes clear of the photo-cell 62 &c., the amplifier 66 is re-energized. The clutch C1 is therefore de-energized by actuation of the relay switch RM2. At the same time, the relay switch RM2 acts through the contacts of a relay switch RM4 to engage a solenoid clutch C2 and thus drive from the conveyer 14 to another toothedwheel impulse emitter 32. The latter produces twice as many impulses per rotation as the impulses produced by the emitter 30. The impulses are, as before, fed to the counter 40, and added to the impulses already received from the emitter 30. The counter 40 in due course switches off the conveyer 14, positioning the load in the strapping station SS, and actuating the strapping shoots 16, 20. Operation: short load.-If the load L2 is so short that its length is less than the separation of the strap feed shoots 16, 20, then restoration of the light beam to fall on the photo-cell 62 by passage of the trailing edge of the load along the conveyer 14 will re-energize the relay switch RM2 and make a circuit through a switch 54 actuated by the second counter wheel 44. Dwell points 52 on the second counter wheel are of such extent that the circuit to the actuating solenoid of the switch RM3 is only made for loads L2 of short length. The switch RM3 controls an over-ride holding circuit for the motor M1, which is kept in circuit until the short load L2 has reached the correct position in the strapping station SS. The switch RM3 includes a time-delay function to control its operation. The relay switch RM2 also makes a circuit through the switch RM3 to the control solenoid SM2 of the transfer switch SM2, which is conditioned to cause operation of the strap feed shoots 18, 20, appropriate to the short length of the load, instead of the strap feed shoots 16, 20.