GB1575683A

GB1575683A - Batch weighing apparatus

Info

Publication number: GB1575683A
Application number: GB2677277A
Authority: GB
Original assignee: Driver Southall Ltd
Current assignee: Driver Southall Ltd
Priority date: 1977-06-27
Filing date: 1977-06-27
Publication date: 1980-09-24
Also published as: DE2746343A1; DE2746343C2; FR2396275B3; FR2396275A1

Description

(54) BATCH WEIGHING APPARATUS (71) We, DRIVER SOUTHALL LIMITED, a British Company, of Field End Road, South Ruislip, Middlesex HA4 OQQ, England, do hereby declare the inevention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: This invention relates to batch weighing apparatus used for accurate and speedy automatic weighing of successive batches of material and products from bulk in an automatic operating cycle, said apparatus including a coarse feed means operable to feed a major part of each batch into a weighpan of the apparatus at a fast rate, and a fine feed means operable to feed the remaining part of the batch into the weighpan at a slower rate ceasing as soon as the batch reaches the predetermined weight, and said apparatus is hereinafter referred to as "batch weighing apparatus of the kind described".

In order to try to reduce inaccuracies it is well-known to provide a fine feed trap as close as possible to the weighpan to intercept a flow of material or products which has already left the fine feed means on its way into the weighpan, as soon as the load in the pan reaches the desired weight. However, residual inaccuracies have remained due to there being an appreciable quantity of material or products still dropping between the trap and the material or products already resting in the pan when the final shut-off occurs, particularly if there is a considerable distance between the trap and the bottom of the pan as may often be the case where a pan is being used to weigh batches far below its full capacity in general purpose apparatus designed for a wide range of loadings, e.g. batches weighing 100--250 grams are often handled by 1000 gram capacity apparatus meaning that the weighpan is less than i full at the completion of a cycle. These problems are made more acute where the product consists of relatively large discrete units such as wrapped or unwrapped sugar confectionary leading to large chance variations in the amounts dropping to the pan, and the impact of these large units falling a considerable distance while balance of the weighpan is being attained adds to the difficulty of obtaining accurate and consistant results.

The object of the invention is to avoid or substantially reduce inaccuracies due to the above causes.

According to the present invention there is provided a weighpan for automatic batch weighing apparatus of the kind described, said weighpan having a main lower part in which a major portion of the batch being weighed is operatively received from feed means of the apparatus, a pocket defined in an upper part of the pan closely adjacent to an exit from the feed means in which the remaining portion of the batch is operatively received while said major portion is held in the main lower part, and discharge means operable to empty the pocket and main part together for delivery of the completed batch in use.

A preferred embodiment of the invention is now more particularly described with reference to the accompanying drawings wherein : Figure 1 is a diagrammatic perspective view of part of batch weighing apparatus showing its operation during an initial stage of a weighing cycle; and Figures 2, 3 and 4 are like views showing respective succeeding stages of the cycle.

The batch weighing apparatus of the kind described comprises a weighpan 10 (e.g. of 1000 gram capacity) carried on a weighbeam (not shown) of conventional construction and having a bottom opening main door 11. Immediately above the open top of pan 10 is a fixed structure 12 which mounts trapping devices referred to hereafter, and leading into the back of this structure is a vibratory coarse feed trough 13, a smaller independently operated vibratory fine feed trough 14 both operated under automatic control (not shown) in conventional manner.

Close to its top pan 10 includes a fine feed or subsidiary door 15 which is hinged so that it can be swung between an open position (Figure 4) at which it hangs substantially vertically, and a closed position (Figures 1-3) at which it abuts the frontwall of the pan to define a small pocket in an upper front corner thereof. A rod 16 links cranked ends of hinge pins carrying doors 11 and 15 so that they are opened and closed simultaneously.

Structure 12 carries an automatically operated coarse feed trap (not shown for clarity) which will shut off the outfeed end of coarse feed trough 13 (while leaving fine feed trough 14 open); an automatically operated fine feed diverter plate 17 which can be swung from a vertical position (Figure 1) to an inclined position (Figures 2--4) at whch it diverts flow leaving fine feed trough 14 into the closely adjacent weighpan pocket; and a fine feed trap plate 18 which can be swung over to abut the lower edge of inclined plate 17 (Figures 3 and 4) to catch material or products leaving trough 14 before they reach said pocket. Plates 17 and 18 project below the bottom of structure 12 so that the trap so formed is as near as practicable to said pocket.

The operation during a weighing cycle is as follows: 1. At the commencement of a cycle (Figure 1) doors 11 and 15 are closed, both traps are open and diverter plate 17 is vertical so that material or products are fed from both troughs 13, 14 to drop directly into the main bottom part of pan 10, this continues until a major portion (e.g. 8e- 90%) of the desired batch has been fed when the coarse feed is stopped.

2. The fine feed stage then commences (Figure 2), the coarse feed trap (not shown) is closed to contain material or product falling from coarse feed trough 13, and diverter plate 17 is moved to the inclined position to direct flow from fine feed trough 14 into the weighpan pocket. This flow drops only a very short distance from the bottom of plate 17 onto door 15 and this distance is unaffected by the quantity or level of material or product 20 in the lower part of pan 10, thus the effect of impact of this material on the final critical weighing operation will be minimal, and only a very small and not greatly variable quantity will be in transit between trough 14 and the pocket at any given time.

3. When the weighbeam responds to the completed batch load in pan 10 (i.e. the total of the quantity 20 in the lower part and what is in pocket) the fine feed is halted and the fine feed trap, plate 18, is closed (Figure 3) to retain anything still leaving trough 14.

The only possible material or product then still in transit to pan 10 is the insignificant amount (if any) between the bottom of plates 17 and 18 and the door 15.

4. Finally the cycle is completed by discharge of the batch (Figure 4), doors 11 and 15 being opened for discharge of both material or product 20 and that which was held in the pocket, while the two traps are kept closed. Doors 11 and 15 are then closed and the apparatus returned to its Figure 1 condition for the next cycle.

While a linkage connecting doors 11 and 15 for substantially simultaneous operation has been described it is also contemplated that they might be independently actuated, and that subsidiary door 15 might be opened for discharge of the pocket slightly in advance (e.g. 2 second) before main door 11 so that all the contents of the weighpan exit from its lower end at the same time.

Door 15 may be a solid plate or may be a resilient element comprising flexible fingers or a brush-like construction.

WHAT WE CLAIM IS:- 1. Weighpan for automatic batch weighing apparatus of the kind described, said weighpan having a main lower part in which a major portion of the batch being weighed is operatively received from feed means of the apparatus, a pocket defined in an upper part of the pan closely adjacent to an exit from the feed means in which the remaining portion of the batch is operatively received while said major portion is held in the main lower part, and discharge means operable to empty the pocket and main part together for delivery of the completed batch in use.

2. A weighpan according to claim 1 wherein the discharge means provides substantially simultaneous discharge from the weighpan of the contents of both said main lower part and said pocket.

3. A weighpan according to claim 2 wherein said pocket is defined in part by a subsidiary door linked to a main door of the weighpan.

4. A weighpan according to claim 2 or 3 wherein the pocket is operatively opened slightly before the main lower part so that the contents of both exit from the weighpan at the same time.

5. A weighpan substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

6. Automatic batch weighing apparatus including a weighpan according to any one of the preceding claims.

7. Apparatus according to claim 6 including a diverter for directing flow from fine feed means either into said lower part or into the pocket of the weighpan.

8. Apparatus according to claim 6 or 7 including a fine feed trap operable to catch at least a major part of any flow leaving the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Close to its top pan 10 includes a fine feed or subsidiary door 15 which is hinged so that it can be swung between an open position (Figure 4) at which it hangs substantially vertically, and a closed position (Figures 1-3) at which it abuts the frontwall of the pan to define a small pocket in an upper front corner thereof. A rod 16 links cranked ends of hinge pins carrying doors 11 and 15 so that they are opened and closed simultaneously. Structure 12 carries an automatically operated coarse feed trap (not shown for clarity) which will shut off the outfeed end of coarse feed trough 13 (while leaving fine feed trough 14 open); an automatically operated fine feed diverter plate 17 which can be swung from a vertical position (Figure 1) to an inclined position (Figures 2--4) at whch it diverts flow leaving fine feed trough 14 into the closely adjacent weighpan pocket; and a fine feed trap plate 18 which can be swung over to abut the lower edge of inclined plate 17 (Figures 3 and 4) to catch material or products leaving trough 14 before they reach said pocket. Plates 17 and 18 project below the bottom of structure 12 so that the trap so formed is as near as practicable to said pocket. The operation during a weighing cycle is as follows: 1. At the commencement of a cycle (Figure 1) doors 11 and 15 are closed, both traps are open and diverter plate 17 is vertical so that material or products are fed from both troughs 13, 14 to drop directly into the main bottom part of pan 10, this continues until a major portion (e.g. 8e- 90%) of the desired batch has been fed when the coarse feed is stopped. 2. The fine feed stage then commences (Figure 2), the coarse feed trap (not shown) is closed to contain material or product falling from coarse feed trough 13, and diverter plate 17 is moved to the inclined position to direct flow from fine feed trough 14 into the weighpan pocket. This flow drops only a very short distance from the bottom of plate 17 onto door 15 and this distance is unaffected by the quantity or level of material or product 20 in the lower part of pan 10, thus the effect of impact of this material on the final critical weighing operation will be minimal, and only a very small and not greatly variable quantity will be in transit between trough 14 and the pocket at any given time. 3. When the weighbeam responds to the completed batch load in pan 10 (i.e. the total of the quantity 20 in the lower part and what is in pocket) the fine feed is halted and the fine feed trap, plate 18, is closed (Figure 3) to retain anything still leaving trough 14. The only possible material or product then still in transit to pan 10 is the insignificant amount (if any) between the bottom of plates 17 and 18 and the door 15. 4. Finally the cycle is completed by discharge of the batch (Figure 4), doors 11 and 15 being opened for discharge of both material or product 20 and that which was held in the pocket, while the two traps are kept closed. Doors 11 and 15 are then closed and the apparatus returned to its Figure 1 condition for the next cycle. While a linkage connecting doors 11 and 15 for substantially simultaneous operation has been described it is also contemplated that they might be independently actuated, and that subsidiary door 15 might be opened for discharge of the pocket slightly in advance (e.g. 2 second) before main door 11 so that all the contents of the weighpan exit from its lower end at the same time. Door 15 may be a solid plate or may be a resilient element comprising flexible fingers or a brush-like construction. WHAT WE CLAIM IS:-

1. Weighpan for automatic batch weighing apparatus of the kind described, said weighpan having a main lower part in which a major portion of the batch being weighed is operatively received from feed means of the apparatus, a pocket defined in an upper part of the pan closely adjacent to an exit from the feed means in which the remaining portion of the batch is operatively received while said major portion is held in the main lower part, and discharge means operable to empty the pocket and main part together for delivery of the completed batch in use.

fine feed means before it reaches the weigh pan pocket.

9. Apparatus according to claim 8 wherein said trap comprises a swinging element movable to cooperate with a diverter plate when the latter is arranged to divert flow to said pocket.

10. Batch weighing apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.