WO2004042335A1

WO2004042335A1 - Automatic combination weighing apparatus

Info

Publication number: WO2004042335A1
Application number: PCT/DK2003/000755
Authority: WO
Inventors: Claus Engelbrecht
Original assignee: Cetech V/Claus Engelbrecht
Priority date: 2002-11-05
Filing date: 2003-11-05
Publication date: 2004-05-21
Also published as: AU2003277834A1; EP1558901A1

Abstract

An automatic combination weighing apparatus (2) comprising a conical dispersion table (6), first conveying means (8) to cause articles (10) fed on said dispersion table (6) to move outwardly and circumferentially thereon, a plurality of second conveyor means (14) for advancing articles thereon towards the front end (16) thereof, into a plurality of pool hoppers (18), a plurality of weighing means (20), said weighing means (20) being circumferentially arranged around the center axis (30) of the apparatus, in such manner that the weighing hoppers (22) are arranged nearest said center axis (30) and the weighing mechanisms (24) is located further away from said center axis (30). The main characterizing feature of the weighing apparatus is that the second conveyor means (14) between the periphery (13) of the conveying means (8) and the pool hoppers (18) are extending in an oblique manner against the center axis (30) of the chute (28) compared to a straight line extending from said center axis (30) and the periphery of the first conveying means (8).

Description

AUTOMATIC COMBINATION WEIGHING APPARATUS

BACKGROUND OF THE INVENTION

This invention relates to an automatic combination weighing apparatus comprising a supply conveyor unit, a conical dispersion table, first conveying means to cause arti- cles fed from said dispersion table to move outwardly and circumferentially thereon, a plurality of feed troughs arranged around said conveying means to receive articles from said dispersion table, and in connection with said feed troughs a plurality of second conveyor means for advancing articles thereon towards the front end thereof, a plurality of pool hoppers below the front ends of said conveyor means, a plurality of weighing means positioned below said pool hoppers, each weighing means including at least a weighing hopper and a weighing mechanism, control circuit means coupled to said weighing means for calculating combinations of weights on the basis of values of weight of articles measured by said weighing means wherein the sum weight of the combination of articles is equal to or closest to within a preset range of allowance to a predetermined weight value of a measured portion of articles, and means for discharging articles from the weighing hoppers of the weighing means corresponding to the predetermined weight value of a measured portion of articles, and a chute with a vertical center axis, for collecting articles discharged from said weighing hoppers and for dumping the articles outside the apparatus, said weighing means being circumferen- tially arranged around said center axis in such manner that the weighing hoppers are arranged nearest said center axis and the weighing mechanisms is located further away from said center axis.

In connection with combination weighing, following parameters are very important to achieve a high capacity, and a high accuracy; swift, precise and uniform batching, swift accept of weight-signal (time between evacuation of a pool hopper until the weighing signal is stable), short uniform drop time (time of travel for a batch measured from the time of full open weighing hopper and the time when said batch has passed out through the chute).

The most essential factors influencing on said important parameters are: -the necessity of an effective distribution of the items so they approach the pool hoppers in a uniform layer. This is best achieved by having as long a vibrating way of transport as possible, i.e. a dispersion table with as large diameter as possible, and long second conveyor means between the periphery of the dispersion table and the pool hoppers.

-a rigid and stable construction of the body of the apparatus, to eliminate low frequent vibrations.

- a minor extraction of the batch of items by emptying the weight hoppers, which is achieved by a short steep tapering distance of the walls of the chute through which the batches are supposed to slide to away from the weighing apparatus.

Operating with a circular ground structure of the construction of an automatic combination weighing apparatus, it will be necessary to compromise between said factors as they are somewhat incompatible in several fields. E.g. if the diameter of the first con- veying means, which most frequently consists of a center vibrator, and the extension of the second conveyor means, this will cause an increase of the diameter of the whole weighing apparatus, and since the hoppers are located in a circle, at the end of the second conveying means, the distance between the outlet of the weighing hoppers and the center of the chute, accordingly will be increased. This will result in a choice between either a narrow angle of slide, or an increased height of the chute, both solutions will cause a long extraction of the of the batch of the items leaving the weight hoppers, and consequently a longer drop time.

Further it is difficult to construct a strong and stable support of the weighing apparatus as its body is build up from the center radially outwardly with the weighing hoppers etcetera arranged in a circle outside the body. To secure the apparatus, it is necessary to reach said body, which only is possible using beams/supports going through a split chute, and fastened to the body. As the available space for such supporting constructions is limited by the spacing between the weighing hoppers, it is difficult to provide a strong and stable support of the weighing apparatus.

As main mechanical parts of the weighing apparatus are located inside and around the body, on the inside of the chute, and outside around the body but on the inside of the chute, any contamination (waist of product, accumulated product, deposits, dirt from mechanical parts or the like) will end in the product zone together with the measured batch.

The above described facts causes major and practically unsolvable problems designing weighing devices, especially in the food- and medicine industry, and to the daily cleaning up the mechanics and components located on the inside of the product zone.

As the main parts of the mechanics are arranged inside and outside the body, it will be impossible or very difficult to make service on the weighing device, without first removing all or almost all surrounding parts such as chutes, hoppers and second conveying means, to get access to the main parts and the weighing device.

An automatic combination weighing apparatus as stated, is disclosed in US-A-4 398 612, where the second conveyor means are extending outwardly from a conical vibrating dispersion table to pool hoppers arranged radially around the dispersion table.

The weighing units comprising said pool hoppers, weighing hoppers and weighing cells, are extending outwardly from the body of the apparatus, and thus being located outside the product zone, which provide for easy access in connection with making service on said items.

However, the feed troughs, radially extending from the periphery of the dispersion table, and the vibrating means in connection therewith, are located in the product zone, and are thus exposed to contamination of the products supplied from the dispersion table. The location of said vibrating means in the body zone makes it very difficult to make service. Further does the disclosed apparatus not provide a long vibrating distance of transport before dispensing, and neither a short steep tapering distance of the walls of the chute through which the batches are supposed to slide to away from the weighing apparatus.

It is the object of the present invention to provide an automatic weighing apparatus of the kind described above providing for a long vibrating distance of transport of items before dispensing, combined with a short steep tapering distance of the walls of the chute through which the batches of items are supposed to pass.

According to the invention this is achieved in that the second conveyor means between the periphery of the conveying means and the pool hoppers are extending in an oblique manner against the center axis of the chute compared to a straight line extending from said center axis and the periphery of the first conveying means, thus the flow of articles between the periphery of the conveying means and the chute are directed only towards center of the chute.

To straighten out the items to be dispensed, it is preferred that the second conveying means in connection with each trough consists of at least one vibrator means for driving said items in the troughs in an inclined linear reciprocating vibrating motion, advancing them to the front end thereof. In this connection, it is preferred that the troughs and the second vibrating means are integrated.

Thanks to the orientation of the second conveyor means deviates from a radial extension from the periphery of the dispersion table, it is achieved, that the vibrating conveying distance of transport of items before dispensing are extended substantially, compared to the distance of transport of the weighing apparatus disclosed in US-A-4

398 612. This will straighten out the items to a uniform layer, before they are lead to the pool hoppers.

Arranging the pool hoppers and the weighing hoppers in a circle around the center axis as stated in claim 3, the diameter of said circle being determined only by the requirements of space from said hoppers in open position, results in a possibility to reduce the diameter of said chute, thus providing for a short steep tapering distance of the walls of the chute through which the batches of items are supposed to pass. This also makes it possible to handle more sticky items and products than by the known weighing de- vices.

To provide for an efficient initial straightening out the supplied items from the supply conveyor via the conical dispersion table, it is advantageous that the first conveying means below said dispersion table to cause articles fed on said dispersion table to move outwardly and circumferentially thereon, consists of a cricoid shaped vibrating distributor, which performs spiral reciprocating vibratory motion, as stated in claim 4. The surface of the vibrating distributor extends at least from the edge of the conical dispersion table to the feed troughs, and the items are transported horizontally and circular along the outer edge of the cricoid shaped vibrating distributor. This means that if one or more openings of the troughs are closed, the items will not clog, but be transported to the next open trough, and pass on to the pool hoppers via the second conveying means.

The combination of the above first and second conveying means, the items are transported from the center of the weighing apparatus to its periphery and down into the troughs and further via the second conveying means to the pool hoppers, located in a circle close around the center axis of the chute. Hereby there is achieved approxi- mately a doubling of the way of vibrating transport of the items (in relation to the diameter of the weighing apparatus) compared to a normal weight. Further there is achieved a short steep tapering distance of the walls of the chute. Accordingly there is achieved a higher frequency of dosing portions, and a more uniform and accurate measuring from the weighing hoppers, thanks to the better extraction of the products in the weighing apparatus according to the invention. Further, it will be possible to increase the diameter of the dispersion table, and the length of the second conveying means, without changing the diameter or the sliding angle of the chute, which collects the outlets discharged from the weighing hoppers to form a batch equal to or closest within a present range allowed to a predetermined weight value.

To achieve a good dispersion of the items supplied from the supply conveyor, it is further preferred that the dispersion table is rotating during the dispersion of items.

The level of articles supplied from the supply conveyor to be dispensed in portions in the automatic combination weighing apparatus according to the invention, is controlled by a level control. The level control comprises e.g. photoelectric cells located at the periphery of the first conveying means and/or a weighing cell on said first conveying means, said photoelectric cells and/or weighing cell being connected with the con- trol circuit means, which is also connected with the supply conveyor to control the supply velocity/volume/amount of articles, where said control circuit means in case of registered deviations from a preferred level/weight of articles on the first conveying means, will adjust the supply velocity/volume/amount of articles, supplied from the supply conveyor.

To provide for good access for servicing the weighing apparatus according with the invention, it is preferred that the supply conveyor unit comprises the conical shaped dispersion table located below the front end of the supply conveyor, said conveyor unit being mounted on a pivot joint and/or displaceable on a rail system, for the displacement of the supply conveyor unit and the dispersion table away from the center of the weighing apparatus, as stated in claim 5. This feature provides for full access to the entire top side of the weighing apparatus, as the conical shaped dispersion table and the supply conveyor can be displaced to a location outside the top side.

To provide for a stable and non vibrating support for the weighing apparatus, the body can be shaped as a hollow, preferably rectangular ring, surrounding the product zone, on which body are mounted pool hoppers and weighing hoppers extending towards the center axis of the weighing apparatus. This opens for a more stable and rigid construc- tion of the carrying parts of the weighing apparatus, since these are not to be arranged in the product zone in the center of the apparatus, where the space for such constructions are narrow. Hereby is it achieved that vibrations from the vibrating means of the first and second conveying means will not propagate and influence the weighing cells. Further there is provided enhanced access to the sensitive, and the mechanical parts of the weighing apparatus.

The shape of the body opens also for a more appropriate location of the vibrating means of first conveying means and the second conveying means as it will be possible to locate these outside the product zone. This will enhance the access to these me- chanical parts in connection with service, and further these parts will not be expelled to contamination of the articles. DRAWING

An example of a weighing apparatus according to the present invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 is a schematic diagrammatical view of the combination weighing apparatus in accordance with an embodiment of the present invention, Fig. 2 shows the same as in figure 1, bur with the supply conveyor and the dispersion table displaced apart from the top side of the weighing apparatus, Fig. 3 is a top view of the combination weighing apparatus in figure 1, Fig. 4 is a top sectional view along the line A- A, in figure 1, showing the upper surface of the first vibrating conveying means Fig. 5 is a top sectional view along the line B-B, in figure 2, showing a top view of the troughs and the second vibrating conveying means, and Figs. 6 & 7 are schematic diagrammatical views of the combination weighing appara- tus shown I figure 1 , in different operating positions.

Fig. 1 shows on diagrammatical form an embodiment of the combination weighing apparatus 2 according to the invention comprising a supply conveyor unit 4 for supplying the weighing apparatus 2 with articles 10. Below and near the front end 5 of the supply conveyor unit 4 is located a conical shaped dispersion table 6 which preferably is rotably connected to said supply conveyor unit 4. The dispersion table 6 might comprise a driving unit (not shown) to perform a rotably movement during dispersion of articles.

Below the conical shaped dispersion table 6 is located a circular shaped vibrating distributor 8 which performs spiral reciprocating vibratory motion, transporting the items 10 towards feed troughs 12 located along the periphery 13 of said vibrating distributor 8. The distributor 8 causes a movement of the articles 10, in a direction illustrated by the arrows 11 in figure A, showing the upper surface 9 of the first vibrating conveying means 8. The direction of movement 11 of the articles 10 causes a longer distance of vibrating transport, which provides for a better straightening out the items to be feed to the second conveyor means 14, in connection with the feed troughs 12. The second conveyor means 14 in connection with each feeding trough 12 consists in the shown embodiment of one vibrating means 14 (the second conveyor means 14 and the their respective feeding troughs 12 are integrated), driving the articles in an inclined linear reciprocating vibrating movement, advancing them to the front end 16, as it appears from figure 1.

The vibrating means 14 are, as it appears from figure 3 and 5, extending in an oblique manner against the vertical center axis 30 of a chute 28 disposed at the lower end of the automatic weighing apparatus 2. Below the front ends 16 of each said vibrating means 14 are located pool hoppers 18 arranged in a circle. The outlet openings 19 of said pool hoppers 18 are located above weighing hoppers 22, also arranged in a circle. Said weighing hoppers 22 stands in connection with weighing mechanisms 24, attached in a known manner to control circuit means 26, for calculating combinations of weights on the basis of values of weight of articles 10 measured by said weighing means (20) wherein the sum weight of the combination of articles (10) is equal to or closest to within a preset range of allowance to a predetermined weight value, and for discharging articles to the weighing hoppers (22) of the weighing means (20) corresponding to the predetermined weight value.

Below the weighing hoppers 22 are located a chute 28 for the receive of portions of measured articles 10 to be carried on to e.g. a not shown packaging device. Said chute 28 has a short steep tapering wall 42, on which the measured portions 32 of articles 10 passes. This provides for the preferred short steep sliding distance for the articles in an acute angle, and thus for increasing the capacity of the weighing apparatus according to the invention.

As it appears from figure 2, the supply conveyor unit 4 with the conical shaped dispersion table 6 suspended below the front 5 is displaceable located on a rail system 34, to enable a displacement thereof away from the upper surface 9 of the conveyor means 8. This makes access to the upper side of the conveyor 8 very easy, and thus makes it easier to clean up, and make service on the weighing apparatus. Figure 3 shows the directions of vibrating movement of the articles 10 between the supply conveyor 14 and the pool hoppers 18.

In figure 4 is the direction of vibrating movement of articles supplied from the disper- sion table 6 shown by the arrows 11, as a combination of a radial movement from the center 30, and a parallel movement with the periphery 13 of the vibrating conveyor 8.

In figure 5 the direction of vibrating movement of articles from the feed through 12, via the second conveying, vibrating means 14, to the pool hoppers 18, located below the front ends 16 of said conveying, vibrating means 14.

In figure 6 and figure 7, is the automatic combination weighing apparatus 2 shown in operation.

In figure 6 is shown how samples 32 of measured articles are discharged via the outlet openings 23 of the weighing hoppers 22 into the chute 28, and with simultaneous loading the pool hoppers 18 with articles via the second vibrating conveying means 14.

In figure 7 is shown how successive samples 32' are discharged to the weighing hoppers from the pool hoppers 18 via the opened outlet opening 19, and where the previous samples 32 of articles 10, are sliding downwards on the short steep tapering wall 42 towards the discharge opening 40 in the chute 28.

As it appears from figure 1, 2, 6 and 7, the automatic combination weighing apparatus

2 are build up on a hollow body 36 in such manner, that the mechanical parts, such as the second vibrating means 14, the weighing mechanisms 24, and other mechanical features necessary for the weighing apparatus, are located on the inward facing side 46 of the body 36, the technical parts of said mechanical features extending into the hol- low body 36, and openings in the outward facing side 44, provides for a excellent accessibility to these parts in connection with repair works and service. Further and very important, the mechanical parts are located outside the product zone 38, and thus, these parts are not expelled to contamination of the articles 10 supplied via the supply conveyor 4. Said arrangement of the mechanical parts makes cleaning up the automatic combination weighing apparatus 2 much easier, since the mechanical parts does not take up space in the product zone 38, thus there will be full access to the product zone 38, and accordingly the pool hoppers 18, the weighing hoppers 22 and the inside of the chute 28. Further the excellent accessibility to the mechanical parts makes it possible to make repairs on one or more of the mechanical/technical features, taking these out of operation, without the necessity of closing down the entire operation with the automatic weighing apparatus according to the invention.

As it appears from figure 1, 2 6, and 1, the automatic combination weighing apparatus

2 are supported of a body 36 surrounding the product zone 38, and on which the first vibrating conveying means 8, and the second vibrating conveying means 14, the troughs 12, the pool hoppers 18 the weighing hoppers 22, the weighing mechanisms 24. This enables a rigid and strong construction of the support of the automatic com- bination weighing apparatus 2, which will have an attenuating effect on possible occurring propagating low frequency vibrations from the vibrating conveying means, which frequently will cause inexact results from the weighing mechanisms.

Further will the construction of the body enable an efficient support of all parts of the automatic combination weighing apparatus 2 according to the invention, without the necessity of legs, beams or supports extending through intermediate wall constructions in chutes or the like.

REFERENCE NUMBERS:

2. automatic combination weighing apparatus

4. supply conveyor unit

5. front end of 4

6. conical dispersion table

8. first conveyor means

9. upper surface of 8

10. articles

11. the direction of transport of articles 10 on 8

12. feed throughs

13. periphery of 8

14. second conveyor means

16. front end of second conveyor means

18. pool hopper

19. outlet openings of 18

20. weighing means

22. weighing hopper

23. outlet openings of 22

24. weighing mechanism 26. control circuit means 28. chute

30. vertical center axis of the chute (28)

32. measured portions of particles

34. rail system for 4

36. body

38. product zone

40. discharge opening of the chute

42. short steep tapering wall in the chute 28

44. outward facing side of the body 36

46. inward facing side of the body 36

Claims

1. An automatic combination weighing apparatus (2) comprising body (36) carrying a supply conveyor unit (4), a conical dispersion table (6), and below that, first conveying means (8) to cause articles (10) fed on said dispersion table (6) to move outwardly and circumferentially thereon, a plurality of feed throughs (12) arranged around said dispersion table (6) to receive articles from said dispersion table (6), and in connection with said feed throughs (12) a plurality of second conveyor means (14) for advancing articles thereon towards the front end (16) thereof, a plurality of pool hoppers (18) below the front ends of said conveyor means (14), a plurality of weighing means (20) positioned below said pool hoppers (18), each weighing means (20) including at least a weighing hopper (22) and a weighing mechanism (24), control circuit means (26) coupled to said weighing means (20) for calculating combinations of weights on the basis of values of weight of articles measured by said weighing means (20), wherein the sum weight of the combination of articles (10) measured in one or more of the weighing hoppers (22) is equal to or closest to within a preset range of allowance to a predetermined weight value of a measured portion (32) of articles (10), and means for discharging articles to the weighing hoppers (22) of the weighing means (20) corresponding to the predetermined weight value, and a chute (28) with a vertical center axis (30), for collecting articles discharged from said weighing hoppers and for dumping the articles outside the apparatus, said weighing means (20) being circumferentially arranged around said center axis (30) in such manner that the weighing hoppers (22) are arranged nearest said center axis (30) and the weighing mechanisms (24) is located further away from said center axis (30), c h a r a c t e r i z e d i n that the second conveyor means (14) between the periphery (13) of the conveying means

(8) and the pool hoppers (18) are extending in an oblique manner against the center axis (30) of the chute (28) compared to a straight line extending from said center axis (30) and the periphery of the first conveying means (8), thus the flow of articles (10) between the periphery (13) of the conveying means (8) and the chute (26) is directed only towards center of the chute.

2. An automatic combination weighing apparatus (2) according to claim ^characterized in that the second conveying means (14) in comection with each trough (12) consists of at least one vibrator means for driving said items in the troughs in an inclined linear reciprocating vibrating motion, advancing them to the front end thereof.

3. An automatic combination weighing apparatus (2) according to claim 1 or 2, characterize d in that the pool hoppers (18) and the weighing hoppers (22) are arranged in a circle around the center axis (30), the diameter of said circle being determined only by the requirements of space from said hoppers in open position.

4. An automatic combination weighing apparatus (2) according to any of the claims claim 1-3, characteri zed in that the first conveying means (8) below said dispersion table (6) to cause articles (10) fed on said dispersion table (6) to move outwardly and circumferentially thereon consists of a circular or cricoid shaped vibrating distributor, which performs spiral reciprocating vibratory motion

5. An automatic combination weighing apparatus (2) according to any of the claims 1 - A, characteri z e d in that the supply conveyor unit (4) comprises the conical shaped dispersion table (6) located below the front end (30) of a supply conveyor (32), said conveyor unit (4) being mounted on a pivot joint and/or displaceable on a rail system (34), for the displacement of the supply conveyor unit (4) and the dispersion table (6) away from the center (30) of the weighing apparatus (2).

6. An automatic combination weighing apparatus (2) according to any of the claims claim 1-5, characteri zed in that the body (36) is shaped as a hollow preferably rectangular ring surrounding the product zone (38), on which body (36) are mounted pool hoppers (18) and weighing hoppers (22) extending towards the center axis (30) of the weighing apparatus (2).

7..An automatic combination weighing apparatus (2) according to any of the claims claim 1-6, characterized in that the vibrating means of first conveying means and the second conveying means are placed outside the product zone (38).