ASSEMBLING ARTICLES

Abstract: A method and apparatus are provided for determining weight variations of similar discrete articles intermingled from a plurality of supply sources in a manner identifying the source producing said variation of weight of the individual articles. To this end, groups of articles composed of unequal but predetermined numbers of articles from at least two said sources (20, 20a) are assembled in receivers (8), the proportions of the articles from the respective sources for each said group being varied in a predetermined manner. When the groups of articles are weighed (28), and the weights related to the known differing proportions of articles from the respective sources in the individual groups, it is possible to determine the source supplying articles of a non-standard weight. In this way weight variations occurring in any one of a number of intermingled streams of articles can be monitored by weighing the groups of equal numbers of said articles.

Description: ASSEMBLING ARTICLES This invention relates to the assembly of groups of articles for container filling arrangements and to methods of assembling articles for filling containers. It is more particularly concerned although not necessarily so, with such apparatus and methods intended to be operated at high rates of filling. Current material handling techniques are often directed to high speed processing to achieve economies of scale. However, when a series of articles are produced as a virtually continuous stream it may be difficult or impossible to check each individual article before packaging, in particular to ensure that the article weight is within some set tolerance. Monitoring the weight of the articles may nevertheless be necessary, not least because the articles may have to satisfy legal weight requirements. In the example of articles in the form of packets or other containers being filled and sealed on-line, weight-monitoring is critical because an aberration in the weight filling mechanism may lead either to high reject rates through underdosing or to wastage of material through overdosing. When the articles travel onwards to be packaged in containers, one known solution is to weigh the containers after they have been filled with known quantities of the articles. This is, however, only effective if the containers are filled from the same source. If the articles arrive from two or more sources, once the two streams of articles are mixed it is not possible to tell simply from the weight of the container which source has produced the articles that have a non- standard weight. An object of the present invention is to provide an apparatus and a method in which, during the supply of a series of similar discrete articles from a plurality of sources to be packaged into containers, when one of those sources begins to supply articles having a non-standard weight, that source can be identified by weighing the containers into which the articles from the plurality of sources have been packed. Accordingly, in one of its aspects the invention provides an article-assembling apparatus wherein a series of similar discrete articles from a plurality of supply- devices are placed in equal quantities in succeeding receivers, each receiver being arranged to be supplied with articles from more than one said supply device, each supply device comprising means for directing the articles to alternative receivers, control means for said directing of the articles being arranged to fill each of a plurality of said receivers with predetermined numbers of articles from at least two said supply devices and said control means directing the articles in predetermined different proportions from the respective supply devices to the respective receivers of said plurality of receivers. With such an arrangement, the weights of the filled receivers, or of respective containers to which the contents of the individual receivers have been transferred, can be measured and a variation from a standard for the weight of the articles that occurs in the articles from one said supply device can be identified with the particular supply device by correlating of the weights of the individual filled receivers or containers with said different proportions of the articles from the respective supply means that they each contain. In another aspect of the invention there is provided a method of assembling articles in groups in which similar discrete articles from a plurality of supply sources are grouped in equal quantities and a variation of weight of the individual articles from any one of said sources is identified, the method comprising assembling the groups of predetermined numbers of articles from the or at least two said supply sources, the proportions of the articles from the respective sources in each said group being varied in a predetermined manner, weighing the individual groups or collected groups of articles and, in the event of a weight deviation being detected, correlating the weighing results with the known proportions of the articles from the respective sources making up weights measured to determine the supply source which is providing articles of a non-standard weight. By way of example, one embodiment of the invention will now be described with reference to the accompanying schematic drawings, in which: Fig. 1 illustrates an apparatus according to the invention, Fig. 2 is a schematic graphical representation of the distribution of articles by the apparatus of Fig. 1, Fig. 3 is a flow diagram illustrating the use of the invention, Fig. 4 illustrates further details of the control unit in Fig. 3, and Fig. 5 illustrates an alternative switching means for the apparatus of Fig. 1. Fig. 1 shows schematically two collating chutes 2,4 each receiving finished articles A from respective processing lines (not shown) from each of which flows a substantially continuous, closely spaced series of individual articles. The chutes 2,4 are arranged over a conveyor belt 6 and are staggered one in front of the other in relation to the travel direction A of the conveyor belt. The conveyor belt 6 is formed with a series of spaced pockets 8 to receive the articles and carry them to a station (not shown) where the contents of each pocket is packed into container. Each chute 2, 4 has entry section from which bifurcated leading and trailing legs 2a,2b;4a,4b descend. At the junction of the leading and trailing legs, a switching guide 12 is provided in the form of a plate or plates pivotable forwards and backwards between alternative positions in which the guide blocks the entry to one or other of the legs of the chute. Thus, only one leg of each chute is open to receive the articles at any time. One function of the switching guide 12 is to ensure that articles are not directed to the spaces between the pockets 8 on the conveyor belt. The spacing of the open lower ends of the. leading and trailing legs of each chute is dependent on the article dimensions and the spacing of the pockets 8 on the conveyor belt, so that at least one exit, from each chute 2,4 is over a pocket at any instant. Thus, as soon as a pocket moves out of register with one leg of a chute, the switching guide can be moved to direct further articles through the other leg into the same or another pocket. As will be described in more detail below, control means (not shown) operate the guides 12 so that from the combined deliveries through both chutes an equal number of articles is deposited in each pocket. It is required to ensure that the weights of the individual articles fall within prescribed limits. When it is necessary to take corrective action to ensure this, it is of course necessary to identify which processing line is producing the non-standard articles, but it would be impractical to check continuously the individual articles if they are being produced in a more or less continuous stream. If the weights of the individual articles from both processing lines are satisfactory, the groups of articles collected in the pockets will have a correct weight, but a correct value there may also conceal a condition in which one supply source is providing underweight articles and the other overweight articles. Nor does a showing of an incorrect group weight indicate which processing line is supplying articles a non-standard weight. In the present apparatus, in order to determine such deviations, the switching guides 12 are controlled so that the equal groups of articles collected in the pockets 8 are made up of predetermined, unequal quantities of articles from the two chutes 2,4, and also so that the proportions of the articles from the respective chutes are varied between one pocket and another. The process is monitored so as to be able to identify the different proportions of articles from the two processing lines in each pocket. The procedure can then be so controlled that when a weight deviation is detected, comparison of the collective weights of the groups of articles carried in the different pockets will identify the line producing the non-standard weight articles. Conveniently the collected groups of articles are packaged and the packages weighed in this procedure, as will be described in more detail below. A particular example of the timing of the switching guides to produce the desired unequal deliveries of articles from the respective sources in each container is illustrated in Fig. 2 which shows the article deposition pattern in graphical form. The vertical axis of the graph represents a time scale, being marked in equal successive units corresponding to the frequency of deposition of successive articles from either of the chutes. The horizontal axis of the graph represents the conveyor length and is marked in units equivalent to the relative movement between the conveyor and the chutes between the instants of depositing successive articles from either chute. That is to say, in the time between the deposition of successive articles from either chute 2,4 the conveyor and chutes will have moved relative to each other by one unit of the horizontal scale. Also illustrated at the top of the graph, below the horizontal scale, are the positions of the conveyor pockets at unit time "1" (vertical scale) . The series of pockets are represented as each extending seven units, ie. the pocket will pass a given position in seven units of time, and successive pockets are spaced apart by three units. To correspond with Fig. 1, with each succeeding unit of time the pocket positions illustrated below the horizontal scale will have moved one distance unit to the right, but for convenience of representation Fig. 2 shows the delivery of the articles with the pocket positions stationary and the chutes moving at the same rate to the left of the graph. The legs 2a,2b;4a,4b of each chute diverge so that at their exits there is a space of five length units between the front and rear legs. The two chutes are so pitched that the trailing leg 2b of the first chute 2 and the leading leg 4a of the second chute 4 are coincident in the travel direction of the conveyor. The delivery of individual articles to the pockets from the first chute 2 is represented in Fig. 2 by the symbol "/" in the appropriate space-time position on the graph. The delivery of articles from the second chute 4 is similarly represented by the symbol "\". Considering first the deliveries from the first chute 2, as shown in Fig. 2, in the first six time intervals corresponding to conveyor positions 1 to 6, a series of six articles are deposited through its leading leg 2a into the pocket 8 shown rightmost at the top of the figure. As the last article reaches the pocket, the leading leg comes out of register from the pocket and over the 7th to 12th time intervals the guide 12 in the chute switches the next six articles through the trailing leg 2b, which has meanwhile come into register with the same pocket. In this phase, therefore, the pocket receives 12 articles from the first chute 2. Meanwhile, the leading leg 2a of the first chute 2 has come into register with the next pocket 8 and in the 13th to 16th time intervals the guide 8 switches a further four articles through the leading leg 2a, into that second pocket. The guide then switches over to deposit a further four articles (17th to 20th time intervals) in the same pocket through the trailing leg 2b. From one processing line, therefore, a total of 12 articles have been deposited in one pocket and 8 articles in the succeeding pocket. During the first few time intervals shown in Fig. 2, the second chute 4 deposits articles in conveyor pockets beyond those shown in Fig. 2. The deliveries through the chute 4 first appear in Fig. 2 at time intervals 9-12 when a further four packets are delivered into the first pocket, through the leading leg 4a of the second chute, simultaneously with the articles from the trailing leg 2b of the first chute. It will be recalled that the trailing leg 2b of the first chute and the leading leg 4a of the second chute are coincident in the travel direction. The guide 12 in the second chute then switches over to deposit in the 13th to 16th time intervals, through the trailing leg 4b, a final four articles into the first pocket. This brings the contents of the pocket to a total of 20 articles. The leading leg 4a of the second chute 4 is now in register with the second pocket and deposits a series of six articles during time intervals 17-22, overlapping with the delivery of articles into that same pocket from the trailing leg of the first chute 2. The guide in the second chute 4 then switches over to direct a further six articles into the second pocket (23rd to 28th time intervals) . There are now 20 articles in the second pocket also but received in proportions of 8:12 from the first and second chutes whereas the proportions from the same two chutes in the first pocket are in the ratio 12:8. It will be appreciated that while the filling of the second pocket is being completed by the second chute, the filling cycle described is begun again (21st time interval) by the first chute which will deposit a total of 12 articles in the next pocket. The unequal proportions of articles from the two processing lines is thus reversed in each successive pocket. Although the foregoing description of the filling sequence refers to the control of the deposit of the articles individually, it will be understood that the articles can equally well be handled in multiples, eg. as pairs of articles. A further feature of the illustrated apparatus is that each chute is so configured in relation to the pockets that it is able to switch each flow of articles between the front and rear legs of the chute in order to allow a substantially continuous series of articles to be deposited into the pockets. It is also possible to operate the assembling procedure described without spaces between the pockets, which may be required for the subsequent handling of the groups of articles but are not essential to the invention. It is possible to arrange that the equal groups of articles assembled together are weighed while in the pockets, but conveniently the articles are packed in their groups into cartons, using any suitable means, and the cartons are weighed to detect a deviation in the weight of the articles coming from either processing line. It will be evident that, if the different proportions of articles deposited from the two chutes into each pocket are monitored, comparing the weights of successive cartons and relating the weights to the different proportions of the articles in the cartons will identify the line in which a deviation has occurred. In fact the procedure will also indicate simultaneous deviations in both processing lines. This procedure and the foregoing assembly procedure is illustrated schematically in Fig. 3. The two article production lines 20,20a deliver their outputs to the two switching devices 2,4. The switching guide 12 of each device is operated by a respective actuator 22 under the control of a common microprocessor control unit 24. The articles assembled in the pockets 8 are boxed in a packing station 26 and the boxes are then weighed in a weighing station 28. Read-out unit 30 supplies the weight reading to the control unit 24 and the value is held in a section of a memory store 32 connected to the unit. In another section of the store 32 data are held for operating the actuators 22 in a predetermined sequence so as to produce the switching patterns of the two devices 12 which give the groups of articles with different proportions of articles from the two production units. The control unit has a further output 34 controlling the speed of the conveyors in the apparatus in order to co-ordinate the operation of the switching guides with the arrival of successive pockets under the units 2,4. The control unit 24 ' is programmed to recognise the time delay between the assembly of each group of articles and the weighing of that group. If, because of some deviation in one of the production lines, the box of articles has a weight outside a preset tolerance, by its access to the article proportions data held in the store 32 the control unit can identify the particular proportions of articles from the two production lines in that box. The next reading of the weighing process will give a different total weight because the proportions of articles in the next box will be different. By comparison of groups of readings, therefore, the control unit is able to determine which of the two production lines is faulty and initiate a correcting action accordingly. Fig. 4 shows further details of the control unit 24, it being understood that the components illustrated can be in the form of software and/or hardware where appropriate. Motion generation unit 36 controls the movements of the conveyors and the switching drives. For the latter it outputs a sequence of pulses to a diverter switch unit 38 that generates the bag diversion switching sequence of the guides 2,4, in synchronism with the movement of the conveyor 6. The diverter switch unit can hold the predetermined switching sequence as an algorithm or as a look-up data table, for example. The weight read-out 30 inputs to an arrangement of averaging filters for controlling the dosing of the tea bags. A first filter 42 of the arrangement outputs average values for a number of read-out values to a comparator 44 which has a target weight value 46 as its other input. In accordance with any error output signal generated, the dosing of the bags in both production lines is adjusted equally. In addition, the weight read-out values are supplied via a changeover switch 48 controlled by the diverter switch unit 38 to input the read-out values to alternative averaging filters 50,52, in dependence upon whether the carton weighed contains more bags from the guide 2 than from the guide 4 or vice versa. The averaged values accumulated in the respective filters 50,52 are input to a second comparator 54 which can thus output a balancing signal when the two processing lines produce bags of different weights, the sign of the signal indicates which line is producing the heavier bags and which the lighter bags. As Fig. 4 indicates, a fully automatic system may be provided in which the control unit signal operates on a dosage regulation apparatus or the like to correct the weight of the articles in the appropriate production line. It is possible, however, for the control unit to respond simply by stopping the production of further articles, or by actuating an alarm to bring human intervention. It is of course possible to collect and package larger or smaller numbers of articles and detect weight deviations by the method described. The difference to be maintained between the proportions from the respective processing lines will depend upon the sensitivity of the weighing apparatus used. This and the size of the groups of collected articles will affect the manner in which the flows of articles are apportioned, and the number of weight read-outs averaged to generate weight control signals. It is thus not necessary to vary the proportions of articles in every succeeding group in all cases. If the weights are only sampled at intervals, the proportional distribution need not be controlled between those intervals. Also, if the articles are to be weighed only after the contents of two or more pockets are collected together e.g. to fill a larger box, it may not be necessary for more than one of the groups of articles so collected to have unequal numbers of articles from the different processing lines. In this case, for different capacity boxes the difference between the quantities of articles from the different sources may be kept the same although the total numbers of articles in the boxes will vary with their capacities. For example, in the illustrated example groups of 20 articles are collected in the pockets. If the groups are used to fill containers holding 80 articles which are then weighed to check for variations in the individual article weights, it may be appropriate to adopt a switching pattern for the articles from the two switching units of 24,16;20,20;16,24;20,20. Repeating this pattern would produce, in alternation one box having 44 bags from the first head and 36 from the second and a following box having 36 bags from the first head and 44 from the second. It will be understood without further illustration that the weight control process described above can also be adapted to operate with more than two processing lines operating in parallel. In the described apparatus, the streams of articles are assembled together in spaced groups by virtue of the spacing of the successive conveyor pockets from each other. If the articles are packaged in their groups, this ensures an interval between the delivery of successive groups from the conveyor, allowing time for packaging to take place. Depending upon the handling of the articles after they have been assembled in their groups it will be understood that other means of time separation may be employed and that the invention may be employed in circumstances in which such separation is not necessary. In a modification of the apparatus described above, the articles arriving from each processing line have three alternative routes, to provide a third exit for reject articles. This can be done by providing each chute 2, 4 with a third leg for the reject articles but Fig. 5 shows an alternative arrangement. In this the chute comprises a fixed hopper 62 in which a single, inclined leg 64 is mounted on a rotary support 66 to be rotatable about a vertical axis. A rotary actuator 68 is operable to pivot the leg 64 to an oppositely inclined position 64a, shown in broken lines. This and the full- line position correspond to the positions of the loading and trailing legs of the chute of Fig. 1. The leg can also be pivoted to a third position 64b at right-angles to the first two positions to provide an exit path, clear of the conveyor 6, for rejected articles. The monitoring means 38 is able to operate the actuator 68 for each of the streams of articles being supplied to the apparatus to direct any reject article detected through the third exit. In order not to disturb the predetermined proportions in which the articles from the two chutes are assembled in the pockets, it is arranged that on a reject signal articles are rejected from both chutes at the same moment although only one of the articles may have triggered the signal. Concurrently, the conveyor movement pauses so that it remains in synchronism with the pattern of delivery of acceptable articles through the leading and trailing exits of the chutes. It should be made clear that the switching means for directing the articles to selected containers have been particularised in this description purely for illustrative purposes. Any suitable known switching means can be substituted, including fluid pressure and vacuum means.

Claims: CLAIMS 1. An article-assembling apparatus wherein a series of similar discrete articles from a plurality of supply devices are placed in equal quantities in succeeding receivers, each receiver being arranged to be supplied with articles from more than one said supply device, each supply device comprising means for directing the articles to alternative receivers, control means for said directing of the articles being operable to fill each of a plurality of said receivers with predetermined and unequal numbers of articles from at least two said supply devices and the articles filling said plurality of receivers being directed from the respective supply devices in predetermined different proportions to the respective receivers of said plurality of receivers. 2. Apparatus according to claim 1 wherein said receivers comprise pockets or trays provided on a conveying means arranged to progress the pockets or trays past said supply devices. 3. Apparatus according to claim 2 wherein the individual supply devices provide alternative exits spaced in the direction of progress of the conveying means, and means are provided to select the exits for the articles passing through each said supply device. 4. Apparatus according to any one of claims 1 to 3 wherein said receivers occupy spaced positions along the conveyor and said supply devices provide alternative exits spaced apart a distance greater than the spacing between the receivers, each supply device having at least one exit registered with a receiver at any instant. 5. Apparatus according to any one of the preceding claims wherein each said supply device is provided with means for the alternative direction of reject articles that are not to be placed in the receivers. 6. Apparatus according to any one of the preceding claims comprising weighing means for groups of said equal quantities of articles and means for determining, from a difference of weight detected between successive groups and said different proportions of articles in the groups, the supply device that has provided articles causing said difference of weight. 7. A method of assembling articles in which similar discrete articles from a plurality of supply sources are assembled in a plurality of groups of equal quantities of articles, and in order to identify a variation of weight of the individual articles from any one of said sources each said group of articles is made up from unequal but predetermined numbers of articles from at least two said supply sources, the proportions of the articles from the respective sources for each said group being varied in a predetermined manner, the individual groups or collected groups of articles being weighed and, in the event of a weight deviation being detected, the supply source which is providing articles causing said deviation is detected by correlation of the weights measured with the known proportions of the articles from the respective sources making up the measured weights of the groups. 8. A method according to claim 7 wherein the groups of articles are collected in receivers which are progressed relative to at least one location from where the articles from the supply sources are transferred to said receivers. 9. A method according to claim 8 wherein the articles from each supply source are directed in a predetermined sequence to alternative locations spaced along the direction of said relative progression for transfer to the receivers. 10. A method according to claim 8 or claim 9 wherein reject articles are detected and removed from the supply of articles before being placed in the receivers and after the detection of a single reject article, the articles supplied at the same instant from all the sources as said reject article are rejected while said relative progression of the receivers is temporarily halted . 11. A method according to any one of claims 7 to 10 wherein the articles from two said sources are so distributed that a succeeding group of articles is formed from unequal numbers of articles from the respective sources apportioned in inverse ratio to the apportionment of the articles in the preceding group of articles to be formed from unequal numbers of articles from the two sources. 12. A method according to any one of claims 7 to 11 wherein a series of containers of different capacities are filled with different multiples of said groups of articles and the proportions of articles from the respective sources in the containers are varied in such a manner that the difference between the quantities of articles from different sources in each container of the series is independent of the total number of articles in the container.

Inventors: BAILEY THOMAS WILLIAM, HADDOW PHILIP GORDON, SEAWARD DAVID ROBERT, VERNON GEOFFREY WILLIAM, BAILEY, THOMAS, WILLIAM, HADDOW, PHILIP, GORDON, SEAWARD, DAVID, ROBERT, VERNON, GEOFFREY, WILLIAM
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1995
Main classification: B65B35
IPC codes: B65B1, B65B35