Patent GB-1107658-A (GB)
Title: Container filling apparatus
Inventor: DAVIES KENNETH EDWARD
IPC: G01G15/00
Filed: 1966-11-14
Abstract: 1,107,658. Filling containers. NATIONAL BISCUIT CO. 14 Nov., 1966, No. 51005/66. Heading B8C. [Also in Divisions G1W and G3R] Filling containers.-Several containers 4 (Fig. 1) filled simultaneously from corresponding feed weighers 3 are subsequently check weighed at 8 and a signal indicating when a container is under-weight is fed back through a distributing device to a memory associated with the corresponding feed weigher which is adjusted when a predetermined number of under-weight containers have been filled. Any loss of synchronism of the distributing device is automatically corrected when a fresh batch of containers, as indicated by a change in the spacing between container, is detected. In the construction described the under-weight containers are discarded, and an adjustment is also made to the memories when over-weight containers are detected. A single memory may be switched periodically to serve each feed weigher in turn. The containers are held by a stop 6 on a continuously moving conveyer 5 while they are filled. They are delivered to the conveyer 8 on which they are weighed by a conveyer 7 moving more slowly than the conveyers 5 and 8. The system may be constructed to provide signals indicating correct weight, to be treated in the same way as over-weight signals. Feed weighers.-The material is weighed in a hopper 15 (Fig. 3) mounted by leaf springs 18 to deflect, when the required weight of material is present, and so obturate an air jet 30 controlling the release of the feed gate 16. A coarse adjustment of the weight delivered is provided by a manual screw adjustment 22 of a coil spring 20, and a fine adjustment of a coil spring 23 is provided by a servomotor 29. Check weigher.-A check weighing beam 45 (Fig. 5) is brought into an equilibrium (detected by a photocell 55 and a mask 59) by current applied to a solenoid 48 from an amplifier receiving its input from the photo-cell 55. The voltage drop developed across a resistor R1 by the balancing current provides a measure of the weight of the package. Circuit arrangements.-The signal representing the weight of the package is compared with adjustable datum signals representing the maximum and minimum permissible weights in differential amplifiers formed by long-tailed transistor pairs (Fig. 6, not shown). Each output is applied to a normally cut-off transistor connected through a diode gate, open only when a container is on the check weigher, to operate a pair of relays, one indicating over-weight containers and the other under-weight containers. A 3-bank distributer uniselector (UN1) (Fig. 11, not shown) stepped by the passage of each container connects contacts on the two relays to each in turn of a series of 4-bank memory uniselectors (109. 111, 112, 113), one associated with each feed weigher. Each memory uniselector is thus stepped in one direction when its feed weigher overfills a container, and in the opposite direction when it underfills. When a predetermined number of containers from any feed weigher has been overfilled or underfilled a wiper of the memory uniselector reaches a contact causing the servomotor 29 (Fig. 3) to adjust the feed weigher in a direction to correct the weight. The servomotor is run for a period determined by a R-C combination in the grid of a thermionic valve (Fig. 12, not shown) connected to an A.C. supply. At the end of the predetermined period the corresponding memory uniselector is homed. The passage of each container is detected by a photo-cell the output from which is connected through a transistor amplifier (Fig. 8, not shown) to operate a relay (RLC/4). The longer gap between batches of containers is detected when voltage across a capacitor, charged through an adjustable resistor while the relay (RLC/4) is released, rises to a value sufficient to cause the operation of a further relay through a transistor amplifier. The further relay causes the distributer uniselector to hunt for the next contact corresponding to the first container of a batch.