GB2075696A

GB2075696A - Apparatus for batch weighing

Info

Publication number: GB2075696A
Application number: GB8112298A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-04-28
Filing date: 1981-04-21
Publication date: 1981-11-18
Also published as: IT8121390A0; DK182380A; DE3115895A1; IT1168123B

Abstract

The apparatus comprises a conveyor (2) having transverse compartments (6) each of which accommodates several articles side-by- side, and a weighing pan (7) which is located below the discharge end of the conveyor and which is automatically emptied when it contains a desired batch quantity. When the weighing pan contains a predetermined fraction of the batch quantity a storage receptacle (10) is swung inwardly below a part of the conveyor width and, thus, intercepts those articles delivered in that region of the width. Thereafter the weighing pan receives articles only from the remaining part of the conveyor width. When the weighing pan has been emptied and is ready for the next metering operation, the storage receptacle delivers the articles temporarily collected in the receptacle to the weighing pan. <IMAGE>

Description

SPECIFICATION Apparatus for batch weighing of articles This invention relates to apparatus for batch weighing of articles, comprising an article conveyor, a weighing pan located below the discharge end of the conveyor and arranged to be automatically emptied when it contains a batch of predetermined weight, and means for reducing the delivery rate of the conveyor when the weighing pan contains a predetermined fraction of said batch weight.

Such apparatus can be used in connection with an automatic or semi-automatic packaging machine to which the successively metered batches of the articles are transferred from the weighing pan. The reduction of the delivery rate of the conveyor during the final part of the filling of the weighing pan makes it possible to effect, in this stage, a fine metering which ensures minimum deviation between the weight of the individual batches and to obtain, at the same time, maximum utilization of the capacity of the packaging machine, because the articles are transferred at a relatively high rate from the conveyor to the weighing pan during the major part of its filling with the set quantity and at reduced rate during the final fine metering stage.

From the accepted German Patent Application (DE-AS) No. 25 26 897 there is known an apparatus of the kind referred to in which the conveyor is composed of two individual driven parts of unequal width. During the initial part of the filling of the weighing pan both conveyor parts are operative, and when the weighing pan contains the predetermined fraction of the desired batch weight, the wider part of the conveyor is stopped following which only the narrower conveyor part discharges articles into the weighing pan.Simul tal.eously the supply rate of articles to the conveyor is reduced by switching a preceding feed conveyor from a position in which it suppiies articles only to the first mentioned conveyor, to another position in which it supplies articles also to a second conveyor, which is identical with the first conveyor and arranged in parallel thereto and which discharges into a second weighing pan. When the fine metering in the first weighing pan has been terminated, the feed conveyor is switched to a third position in which it delivers articles to the second conveyor only.

This known apparatus is complicated and correspondingly expensive since its operation requires two automatic weighing pans with associated control systems for the repeated switchings of the feed conveyor and for the intermittent operation of the parallel-connected conveyors. The several movable component parts of the apparatus are subjected to wear and involve the risk of failures which reduce the capacity or through-put of the apparatus.

According to the present invention there is provided an apparatus of the kind referred to, characterized in that the conveyor is formed with a plurality of transversely extending compartments each dimensioned to accommodate several articles side-by-side, and in that the means for reducing the delivery rate of the conveyor comprises an upwardly open storage receptacle extending across a part of the width of the conveyor intermediate the conveyor discharge end and the weighing pan, and means for causing the receptacle to interrupt the flow of articles delivered from said part of the conveyor width in response to a control signal delivered from the weighing pan when said fraction of the batch weight is contained therein, and to empty the receptacle into the weighing pan after the pan has been emptied.

With an apparatus according to the invention it is possible to obtain substantially the same throughput as in the known apparatus referred to above but with only one weighing pan and one conveyor which may be operated continuously at a constant speed so that the apparatus is substantially simpler, cheaper, and more reliable in operation. After the partial interruption of the article flow by the receptacle those articles, which are discharged from the associated part of the conveyor width, will be collected in the receptacle, and the transfer of articles to the weighing pan occurs only from the remaining part of the conveyor width.The articles, which thus have been temporarily stored in the receptacle, fall down into the weighing pan after the batch previously metered in the pan has been discharged therefrom, and, consequently, the weighing pan receives at once a substantial part of the quantity to be metered in the next weighing operation. By means of a simple receptacle and a correspondingly simple control and drive system there is thus obtained the required fine metering during the end phase or stage of each weighing operation and a simultaneous crude metering of the following batch prior to the initial phase of the next weighing operation.

In a preferred embodiment of the invention the storage receptacle comprises a bowl having a bottom wall and a rear wall remote from the conveyor, and means for pivoting the bowl about a horizontal axis between a first position in which its bottom wall overlies the weighing pan and is downwardly inclined towards the rear wall, and a laterally displaced second position in which the bottom wall is clear of the trajectory of articles falling from the conveyor discharge end and is downwardly inclined towards the weighing pan.

This feature permits to design a receptacle of suitably large volume which does not take up substantial vertical space between the conveyor and the weighing pan.

It is pointed out that from US Patent Specification No. 3 241 625 there is known a weighing apparatus in which a similar bowl is pivotally mounted intermediate the discharge end of a conveyor and a subjacent weighing pan across the full width of the conveyor. In this known apparatus the conveyor is , however, operated intermittently in that it is stopped when the weighing pan contains the full batch weight. Consequently, no final fine metering stage takes place and the bowl serves only for intercepting articles which drop beyond the conveyor discharge end due to their own inertia and/or because the conveyor does not stop instantaneously in response to the stop signal delivered by the.

weighing pan.

There may be provided a linkage coupling the bowl to a flap, which pivots in the opposite direction of the bowl about a second horizontal axis adjacent the conveyor discharge end and which has a lower edge that in said second position of the bowl is located closely adjacent the front edge of the bottom wall of the bowl. This feature reduces the neccessary pivot angle of the bowl between its end positions because the pivotal flap obstructs a part of the article trajectory from the conveyor to the weighing pan when the bowl assumes its second position. In its open position the flap may additionally serve as a chute for guiding articles from the associated section of the conveyor width down into the weighing pan.

Across the remaining part of the conveyor width there may be arranged obturating means adapted to obstruct the trajectory of the articles from the conveyor to the weighing pan during the emptying of the weighing pan and to liberate the trajectory after termination of the emptying. This feature ensures that articles which during the emptying of the weighing pan are discharged from said part of the conveyor width are stopped and permitted to continue down into the weighing pan only during the following metering operation.

This invention will be described in more detail below with reference to the accompaying schematical drawings in which Figure I is an elevation of a batch weighing apparatus embodying the invention, and Figure 2 is a side view of the apparatus seen in the direction of arrow 11 in Fig. 1.

On the frame 1, the detailed structure of which has not been shown, of the apparatus there is mounted an upwardly inclined conveyor 2 consisting of two parallel endless chains 3 between which equispaced horizontal slats 4 are secured. Each chain 3 is trained over sprockets (not shown in detail) at its upper and lower end. During operation of the apparatus the upper flight of conveyor 2 moves in the direction indicated by an arrow in Fig. 1. Below that part of the conveyor there is provided a stationary plate 5 and closely adjacent the ends of slats 4 there are located stationary side rails (not shown) such that between succesive slats 4, the plate 5, and the side rails there are defined a series of compartments 6 for the transportation of articles (not shown) to the upper discharge end of the conveyor.The conveyor width between said two side rails has been chosen such that in each compartment there is room for a plurality of the articles in question side-byside.

Below the upper discharge end of conveyor 2 a weighing pan 7 for automatic metering of the articles delivered from the conveyor is (in a known manner) suspended and balanced by means of a spring or weight which is adjusted according to the desired batch quantity. In the embodiment shown the bottom of weighing pan 7 is formed by two plates 8 each can pivot about a transverse axis 9. When the weighing pan contains the adjusted quantity of articles its bottom plates 8 swing out and release the articles for further processing, such as in a packaging machine. When the weighing pan has been emptied plates 8 swing back (in a known manner) and thus close the bottom of the weighing pan.

A storage bowl generally designated by 10 is pivotally suspended on frame 1 by means of a horizontal shaft 11 located above that part of the cross-section of weighing pan 7 which is remote from conveyor 2. Storage bowl 10 is formed as a scoop having two parallel side walls 12, a bottom wall 1 3 and a rear wall 14 at the end remote from the conveyor. Bowl 10 is pivoted about shaft 11 from an open position, shown in full lines in Fig. 1, to a closed position shown in dot-anddash lines, by means of a fluid ram 15, the housing of which is hinged to frame 1 while its piston rod is hinged to one side wall 1 2.

As seen in Fig. 2 in which conveyor 2 has been ommited for the sake of clarity, storage bowl 10 extends only across a part of the width of the weighing pan 7 which in turn is substantially equal to the width of the compartments 6 of the conveyor between the previously mentioned side rails (not shown).

Across the same section of the width of weighing pan 7 there extends a flap 1 6 which is hinged to frame 1 on a transverse horizontal shaft 1 7 located closely below the upper discharge end of conveyor 2. To flap 16 there is secured an arm 1 8 which through a link 1 9 is connected to storage bowl 10 so that the pivoting of this bowl, as described above, between its two end positions is accompanied by a pivoting of flap 1 6 in the opposite direction. In its position shown in full lines, the flap extends from the conveyor downwardly and inwardly above weighing pan 7, and in the other end position of the flap its lower edge is located closely adjacent the from edge of bottom wall 13 of bowl 10, as appears from Fig. 1.

Above the remaining part of the width of the conveyor 2 and weighing pan 7 there is mounted a stationary plate 20 (Fig. 2) which is aligned or flush with flap 1 6 when the latter is pivoted to the position shown in full lines in Fig. 1. Above the same width section of the conveyor and the weighing pan there extends a further flap 21 which is pivotally supported in frame 1 about a horizontal shaft 22, and the end positions of which have been shown in full lines and in dot-and-dash lines, respectively, in Fig. 1. Flap 21 is pivoted between its two positions by means of a fluid ram 23 which has been shown- schematica!ly only in Fig. 2.

In the following description of the operation of the apparatus the term "crude metering zone" is employed to designate that part of the width of conveyor compartments 6 and weighing pan 7 which is occupied by storage bowl 10 and the cooperating flap 16, and the term "fine metering zone" to designate the remaining part of the conveyor width, which is co-extensive with the stationary plate 20 and the cooperating flap 21. In the embodiment disclosed the fine metering zone comprises about 40% of the conveyor width but this figure can vary dependent inter alia upon the desired metering accuracy. It will be understood, however, that said zone shall be at least wide enough to accommodate one of the commodities or articles to be metered by means of the apparatus.

Said articles, which e.g. may be potatoes, onions or carrots to be packaged in a following packaging machine, are supplied to the lower inlet end (not shown) of conveyor 2 in such a way that as far as possible the articles fill the entire width of each compartment 6.

For this purpose there can be used an apparatus as that described in my International Patent Application No. PCT/DK 81/00019 which has an oscillating supply chute with a V-shaped cross-section. Irrespective of how the articles are supplied to the conveyor it is essential to ensure that as far as possible the fine metering zone of each compartment 6 is filled.

When weighing pan 7 is empty, the movable component parts of the apparatus assume the positions shown in full lines in Fig.

1. From the upper end of the continuously running conveyor 2 the articles fall down into weighing pan 7, possibly along the chute formed by the stationary plate 20 and the cooperating flap 1 6 aligned therewith. When the weight of the articles transferred to pan 7 has reached a preset fraction of the desired metering quantity, for example about 80%, the resulting vertical movement of the weighing pan actuates a switch (not shown) which through a suitable control system actuates the fluid ram 1 5 to retact its piston rod whereby storage bowl 10 and flap 1 6 are pivoted to their closed positions shown in dot-and-dash lines. For the time being flap 21 remains in its position shown in full lines.

The trajectory of the articles down into weighing pan 7 is now obstructed in the crude metering zone by the bottom wall of bowl 10 and the flap 1 6 so that those articles, which in this zone are discharged from the conveyor, are temporarily received in bowl 10 while only those articles, which are discharged in the fine metering zone, fall down into weighing pan 7, the filling of which consequently occurs at a correspondingly slower rate.

When the preset batch quantity is present in weighing pan 7, which consequently has moved a corresponding length further downwardly, a switch is actuated, which through a mechanism (not shown) pivots bottom plates 8 of the weighing pan outwardly and which also causes fluid ram 23 to pivot flap 21 to the position shown in dot-and-dash lines in Fig. 1. Storage bowl 10 and flap 1 6 remain in their positions until weighing pan 7 has been emptied.

The pivoting of flap 21 to the position just mentioned causes the flap to form, together with plate 20, a downwardly closed, wedgeshaped chamber, and any articles that during the, incidentally rather fast, emptying of weighing pan 7 are delivered from the fine metering zone of the conveyor, are intercepted in the chamber and, thus, do not disturb the metering. Any articles, which at the same time are discharged in the crude metering zone, are intercepted in bowl 10 as previously.

When weighing pan 7 has been emptied and thereby, under the influence of the balancing force, lifted to its initial position, bottom plates 8 of the pan close in the usual way. The control signal, which releases the closing of the weighing pan, can simultaneously be utilized for actuating rams 1 5 and 23 so that storage bowl 10 and flaps 1 6 and 21 are pivoted back to their initial positions following which the next metering operation begins with the transfer of the stored articles from bowl 10 to weighing pan 7 together with those articles which might have been present in the chamber between flap 21 and plate 20.

Claims

1. Apparatus for batch weighing of articles, comprising an article conveyor, a weighing pan located below the discharge end of the article conveyor and arranged to be automatically emptied when it contains a batch of predetermined weight, and means for reducing the delivery rate of the conveyor when the weighing pan contains a predetermined fraction of said batch weight, characterised in that the conveyor is formed with a plurality of transversely extending compartments each dimensioned to accommodate several articles side-by-side, and in that the means for reduc ing the delivery rate of the conveyor comprises an upwardly open storage receptacle extending across a part of the width of the conveyor intermediate the conveyor discharge end and the weighing pan, and means for causing the receptacle to interrupt the flow of articles delivered from said part of the conveyor width in response to a control signal delivered from the weighing pan when said fraction of the batch weight is contained therein, and to empty the receptacle into the weighing pan after the pan has been emptied.

2. Apparatus as claimed in Claim 1, characterised in that the storage receptacle comprises a bowl having a bottom wall and a rear wall remote from the conveyor, and means for pivoting the bowl about a horizontal axis between a first position in which its bottom wall overlies the weighing pan is downwardly inclined towards the rear wall, and a laterally displaced second position in which the bottom wall is clear of the trajectory of articles falling from the conveyor discharge end and is downwardly inclined towards the weighing pan.

3. Apparatus as claimed in Claim 2, characterised by a linkage coupling a bowl to a flap, which pivots counter to the pivoting of the bowl about a second horizontal axis adjacent the conveyor discharge end, and which has a lower edge that in said second position of the bowl is located closely adjacent the front edge of the bottom wall of the bowl.

4. Apparatus as claimed in any of Claims 1 to 3, chatacterised by obturating means extending across the remaining part of the conveyor width and adapted to obstruct the trajectory of the articles from the conveyor to the weighing pan and to liberate the trajectory after termination of the emptying.

5. Apparatus as claimed in Claim 4, characterised in that the obturating means comprises a stationary plate extending downwardly from the conveyor and a flap mounted for pivoting about a horizontal axis and having a lower edge which in the obturating position is in contact with the stationary plate.

6. Apparatus as claimed in Claim 5, when dependent on Claim 3, characterised in that the stationary plate is aligned with the pivotal flap of the storage receptacle when the receptacle assumes its second position.

7. Apparatus for batch weighing of articles substantially as described herein with reference to and as illustrated in the accompanying drawings.