Patent GB-691907-A (GB)
Title: Improvements in or relating to automatic weighing apparatus
IPC: G01G19/22
Filed: 1949-08-10
Abstract: 691,907. Automatic feed weighers. LINDARS, H. Aug. 30, 1950 [Aug. 10, 1949], No. 20831/49. Class 143 [Also in Group XL (b)] In an automatic feed weigher, cutoff is effected by the engagement of an arm 2, Fig. 1, movable in accordance with the weight of material in a weighing receptacle 4, and a pair of contacts 7 carried at the end of an arm 6 which is movable to a number of positions, corresponding to predetermined weights by a remote control system. The cut-off of material flowing from a hopper 27 to the receptacle 4 is effected by an apertured slide 28 which is reciprocated by a rack and pinion 31 and a motor 30. The arm 6 is set by a step-by-step motor 8 which also operates impulse generating contacts 9. When a predetermined number of impulses have been received by a control circuit, the motor is de-energized and feed commences. In a modification, Fig. 2, the step-by-step motor 8 is replaced by a rotary motor 8<SP>1</SP> which drives through a clutch 13 and gearing 14, 15 and 20, both the arm 6 and a commutator and slip ring assembly 16, 17, connected in the circuit shown in Fig. 3. This circuit operates as follows: With the contacts 10 closed, due to the arm 6 being in its zero position, relay E/2 is energized and, over contacts E1, open circuits the reverse winding R of motor 8', and closes contacts E2. Selector arm 22 is now moved manually to the selected stud 23 corresponding with the required weight, and the button S is operated so that relay A/3 is operated and energizes the forward winding F of motor 8' over contacts A1, locks up over contacts A2 and - closes contacts A3. Rotation of commutator 16 by the motor 8<SP>1</SP> intermittently energizes relay P/1 so that the contacts P1 are alternately opened and closed so impulsing the driving magnet CS of the counting uni-selector. The motor 8' also drives arm 6 and, on opening of contacts 10 relay E/2 is de-energized and, after a short delay, opens contacts E2 and isolates button S. The wipers W1-W4 are stepped by magnet CS until, in the example shown, they reach the sixth contact, corresponding with the pre-selected sixth contact 23, whereupon relay B/4 is energized and locks up over contacts B2. Contacts B1 open and de-energize relay A/3, contacts A3 open and relay P/1 is no longer impulsed by the commutator 16. Contacts A1 and El resume the positions shown, but since relay B/4 is energized, contacts B3 remain open and the motor stops. Magnet CS is connected through its self-drive contacts 25 with the positive main over closed contacts B4 and the wipers step round to the zero position. The flow of material is initiated by operating button SF so energizing relay C/2 which locks over contacts Cl and energizes the winding M of motor 30 over contacts C2 to cause the slide 28 to open the feed duct. On a predetermined weight of material accumulating in the bucket 4 the arm 2 closes contacts 7 and so energizes relay D/1 which, over contacts D1 deenergizes relays B/4 and C/2. Over contacts B3 the reverse winding R of motor 8<SP>1</SP> is energized and the motor returns arm 6 to its zero position where it closes contacts 10 and energizes relay E/2 which open circuits motor 8' over contacts El, and closes contacts E2 for the button S. Simultaneously, over contacts C2 the motor 30 is deenergized and the slide 28 which is biased into a closed position effects cut off. The circuit is now in its initial condition. The weigher may also be controlled by an automatic programme selecting apparatus such as that generally described in Specification 688,614, [Group XXXVIII]. One example of such an arrangement is shown in Fig. 4 in which the receptacle 4 is fed with materials contained in six different hoppers. On energizing the circuit with the contacts 10 closed by arm 6, relay E/2 is energized and closes contacts E2 so that when button SP is operated the magnet PS is energized and, on subsequent release of this button, the wipers of uni-selector switch levels PSL1-PSL4 are stepped round one contact, relay E/2 is de-energized and contacts El re-close. The wiper on level PSLI is now connected with the tenth contact of counting uni-selector level CSL1, this contact, corresponding with a weight of ten units is taken as an example only. Slow release relay A/2 is now energized over normally closed contacts El, B1, D1 and the impulsing contacts 9 associated with the step-by-step motor 8 (see also Fig. 1). The consequent closure of contacts A1 energizes motor 8 which opens contacts 9, but relay A/2 does not release while the motor 8 is making its stroke, after which, since contacts 9 are re-made, the relay is re-energized; thus the motor makes a number of strokes rotating arm 6 stepwise. Simultaneously the magnet CS is intermittently energized over contacts A2 and steps its wipers at levels CSL1, CSL2 in unison with the setting arm 6. This stepping continues until wiper CSL1 contacts live contact No. 10 whereupon relay B/5 is energized and open circuits relay A/2 at B1; so stopping motor 8, locks up over contacts B5 which also connect the positive main to button SF, energizes magnet CS over contacts B2 and self drive contacts 25 so returning the wipers of switch CSL to zero, and closes a circuit over contacts B3, the wiper at level PSL4, the first contact and lamp H1 which indicates the arm 6 is set for the first commodity. Button SF is next operated so energizing relay C/3 which locks up over contacts C3, connects the positive main to the wiper at level PSL3 over contact C1 and so enerigzes the winding M1 of a motor which starts the feed from the first hopper, and operates an indcating lamp T over contacts C2. When the weight of material in the receptacle 4 reaches a predetermined value (10 units in this example) the contacts 7 are closed and, over contacts B4 relay D/2 is energized and operates make-before-break contacts D2 which energize the driving magnet PS and de-energizes relay C/3 and B/5. Contacts C2 open and extinguish lamp T, and contacts C1 open and deenergize motor M1 so stopping the feed. Relay D/2 is de-energized by the opening of contacts B4 and opens the make side of contacts D2 so de-energizing magnet PS and causing the wipers at levels PSL1-PSL4 to step round onto No. 2 contact. The circuit is now prepared for the next setting of arm 6 to weigh out a predetermined weight (in this example five units) of material from a second hopper. A selector switch 32 is provided between contact No. 5 of level PSL1 and a number of contacts on the counting selector level CSL1 thus enabling the weight of commodity No. 5 to be varied between programmes; similar switches may be incorporated with the other contacts of level PSL1. After the various commodities have been weighed out, in this example six in number, the wiper of level PSL2 passes onto contact 7, strapped to the remaining contacts, whereupon the self drive contacts 33 return all the wipers of switch PSL to zero and, simultaneously, relay A/2 is impulsed through the impulsing contacts 9 so that the motor 8 also returns the arm 6 to zero where it closes contacts 10 and energizes relay E/2. The circuit is now conditioned to repeat the next programme. In a modification the programme selector switches are replaced by a perforated chart of insulating material separating a series of feelers from a conducting surface similar to the arrangement described in Specification 688,614, [Group XXXVIII]. In a further modification, Fig. 5, the contacts 7 are dispensed with and the arm 2 carries a pair of mirrors 34, 35 which reflect a beam of light from a fixed projector 36 to a second pair of mirrors 37, 38 on the setting arm 6. When the arms 2, 6 are aligned the mirror 38 projects a beam of light through a bore 5a onto a photo-cell 39 which operates a relay (not shown) having contacts equivalent to contacts 7. Specification 691,906, [Group XXXVIII], also is referred to.