Method and system for assembling multiple items at a target total weight

Abstract

The present invention relates to a method for collecting a plurality of items at a target total weight, the method comprising the steps of: supplying the items to a plurality of weighing units to obtain measured weight values ​​of the items; performing a combination calculation based on the measured weight values ​​and selecting a combination of these measured weight values ​​such that the sum of these combinations matches the target weight; and collecting the items of the weighing units whose measured weight values ​​are part of the combination, wherein the weighing units are conveying elements movable by levitation relative to a work surface and capable of following different trajectories between at least two areas of the work surface, one of which is a loading area where the items are supplied to the weighing units and another of which is an unloading area where the weighing units that are part of the combination discharge their contents into at least one item collecting section.

Description

[Technical Field]

[0001] The present invention relates to a method and system for assembling a plurality of items at a target total weight, for example, within a specified range. The present invention can be used in packaging processes, and is particularly relevant for feeding a plurality of items of different individual weights into a container so that the combined weight of the items is close to the target weight within an acceptable range. The present invention also relates to a combination scale comprising or using the system of the present invention. [Background technology]

[0002] In the particular field of packaging items into containers, there is a recurring need to collect a number of items of different individual weights so that the collection has a total weight within a specified range, which may be a very narrow range and in practice a target weight value with a very small tolerance.

[0003] This need becomes even more pronounced when the items to be packaged are individual items, e.g., fruits and vegetables, which inherently vary in individual weight. When a collection involves assembling multiple individual items with a target weight, a commonly known solution is to prepare multiple such items and find a combination whose weight sums to the target weight.

[0004] This creates what is known as a combination scale or balance.

[0005] In the particular field of packaging, combination scales or balances have been developed and improved over the years.

[0006] In a packaging process requiring a large number of operations per unit time in a combination weighing machine or combination scale, items are supplied by gravity to a plurality of concentrically arranged weighing units, the measured weight values ​​of the items are obtained at each weighing unit, one combination of the weight values ​​is selected so that the sum of the weight values ​​matches a target weight or is as close as possible to the target weight, and the items included in the weighing units that are part of the selected combination are removed by gravity to a central collection section.

[0007] This particular concentric arrangement of the metering units entails several drawbacks.

[0008] Among these are the facts that the greater the accuracy required, the more weighing units are needed to find the weight combination that meets the target, and that their concentric arrangement means that the scale takes up not only more space horizontally but also more space vertically.

[0009] In order for the central collection section to quickly and efficiently concentrate the articles at the removal point, such as the top opening of a bag, it is necessary for this collection section to have a minimum inclination, and the greater the number of weighing units, the further apart the weighing units that are part of the combination may be due to their concentric arrangement, and as a result, if the principle of minimum inclination of the collection section needs to be met simultaneously, the greater the vertical movement required by the collection section to collect the articles removed from these weighing units.

[0010] This situation is complicated when the nature of the product causes it to clump or pack together in the collector, potentially causing blockages, and / or does not pass properly through the collector.

[0011] Multi-deck or multi-level combination scales have emerged with the dual objective of increasing the number of possible combinations without increasing the number of weighing units and increasing the speed of operation over time. For example, by having multiple pre-load drawers, multiple weighing units below the pre-load drawers, and multiple spare drawers below the weighing units, not only can items contained in the weighing units be part of a combination, but also items that have already been weighed and removed from the spare drawers.

[0012] Naturally, this leads to an increase in the vertical dimension of the combination scale and the appearance of other problems: for example, continuous loading and unloading of items between different levels of drawers and / or weighing units can cause damage to the items, the cost of the scale increases due to more moving parts and more maintenance required, a more complex programming system is required, and the working environment may change due to increased noise, etc.

[0013] Another significant drawback is cleaning: some combination scales require handling of products that may leave residue as they pass through the weighing drawer and / or unit, which requires laborious cleaning operations on combination scales that have numerous nooks and crannies and spaces that are easily contaminated, such as spaces at heights beyond the operator's reach, and which take a lot of time to perform properly, during which the scale is out of service.

[0014] Another drawback must be added regarding the accuracy of weighing in the weighing unit, which uses weighing methods using load cells or various gauges, which require a stabilization time between two successive weighings to provide an accurate weight measurement.

[0015] Patent Document 1, disclosed in 1995, is an example of such a multi-level combination weigher. Despite the age of this disclosure, combination weighers used in packaging processes continue to implement the same technical principles and are not significantly different from each other structurally, with most of the focus being on improvements to the internal logic, or operating software that controls loading and unloading, and the combination logic that results in optimal weight combinations.

[0016] Recent proposals for combination weighers are found in, for example, Patent Documents 2, 3, and 4.

[0017] In other packaging processes with a small number of operations per unit time, linear combination weighers can also be used, i.e., weighing units are arranged adjacent to each other facing a common collection point. Items are manually loaded onto the weighing units, and only the weighing units that are part of the combination deliver their loaded items to the collection point. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] European Patent No. 0640814 [Patent Document 2] European Patent No. 3236220 [Patent Document 3] European Patent No. 1832856 [Patent Document 4] European Patent No. 3617668 Summary of the Invention [Means for solving the problem]

[0019] To solve the above mentioned drawbacks, a method according to claim 1 is disclosed.

[0020] The present invention is a method for collecting a plurality of items at a target total weight, the method comprising the steps of: supplying the items to a plurality of weighing units and obtaining measured weight values ​​of the items at each weighing unit; performing a combination operation based on the measured weight values ​​and selecting a combination of the measured weight values ​​whose sum matches the target weight; and collecting the items of the weighing units whose measured weight values ​​are part of the combination.

[0021] The method is characterized in that the weighing unit is a conveying element that is movable by levitation relative to a substantially flat working surface and can follow different trajectories between at least two areas of the working surface, one of which is a loading area where items are fed to the conveying element and another of which is an unloading area where the conveying element that is part of the combination discharges its contents into at least one item collector.

[0022] According to another aspect of the invention, a system is provided that is particularly suitable for implementing the method of claim 1.

[0023] The system includes a supply unit for supplying articles to a plurality of weighing units, the supply unit being for obtaining measured weight values ​​of the articles at each weighing unit, a control unit programmed to perform a combination operation based on the measured weight values ​​and to select a combination of these measured weight values ​​whose sum matches a target weight, and at least one collector of articles supplied to the weighing units whose measured weight values ​​are part of the combination.

[0024] Essentially, the system is characterized in that the weighing units are conveying elements that are movable by levitation relative to the work surface and can follow different trajectories between at least two areas of the work surface, one of which is a loading area where a supply section supplies items to the conveying element and another of which is an unloading area where a conveying element that is part of the combination discharges its contents into at least one item collecting section.

[0025] The present invention is adapted from known floating transport proposals, which will be explained in more detail later, and gives them hitherto unknown applications, such as their involvement in associative weighing, more particularly in the implementation of combination weighers.

[0026] In an interesting embodiment of the invention, the work surface is substantially flat and horizontal, so that the method can be carried out on a surface that is easily accessible to the operator, easily cleaned, and of a height that is easily customizable, as will be understood from the following description, i.e., a large number of weighing units, i.e., conveying elements, required in the production process can be incorporated without increasing the height dimension of the system.

[0027] Further variants and preferred embodiments of the invention are set forth in the dependent claims.

[0028] It is envisaged that the work surface is a horizontal or substantially horizontal surface, the transport element includes a floating base and at least one container carried by the floating base and suitable for the supply section to load items in the loading area, and the system comprises means for discharging the items into at least one item collection section in the removal area.

[0029] The means for ejecting the articles may include a movable portion of the work surface at the unloading area.

[0030] At least one container carried by the floating base may be a tipper.

[0031] In this case, in a variant, the means for discharging the items includes at least one tilting mechanism in the removal area, which, by mechanical connection with the tipper, can ensure its tilting action and the discharge of the items contained therein into at least one item collection section.

[0032] In one variant, the tilting mechanism and the tipper have complementary means for interconnection, and the tilting mechanism is configured to be simultaneously connected to the tippers of two or more conveying elements, thereby ensuring the tilting operation and the ejection of items contained in the tippers of two or more conveying elements into the item collection section.

[0033] The complementary means of interconnection may comprise a coupling protrusion on the tipper and a rail on the tilting mechanism, the rail being oriented parallel to the work surface and securely attached to an arm that rotates about an axis oriented parallel to said work surface between at least two positions: one is a coupling position A, in which the rail is positioned within the reach of the coupling protrusion of the tipper, and the coupling protrusions of the tippers of two or more conveying elements moving over the work surface can be inserted into the rail through a first end of the rail, and another is a tilting position B, in which the protrusion tilts the tipper that is inserted into the rail.

[0034] The work surface includes at least one outlet formed by an edge region of the work surface, where a plurality of conveying elements forming part of the combination can converge and from which items in the container can be discharged to an item collection section.

[0035] The edge region may be an outer edge region, i.e., the outer edge region of the periphery or contour of the work surface, or an inner edge region, i.e., the inner edge region of the periphery or contour of an opening in the work surface.

[0036] In one variation, the at least one article collection section includes a hopper.

[0037] In one variant, the work surface includes a substantially coplanar selection area, the selection area being dimensioned to spatially arrange a number N of transport elements on the selection area that is greater than the number n of transport elements that are part of the combination, and the control unit is programmed to cause the movement of the transport elements in a loop from the loading area to the selection area, from the selection area to the unloading area, and from the unloading area back to the loading area.

[0038] In one embodiment, the spatial arrangement in the selection area is a matrix arrangement, in which waiting rows, whose column positions can be occupied by transport elements waiting to be selected as part of a combination, are arranged alternately with passing rows, and transport elements selected as part of the combination and waiting in rows adjacent to the passing row are first moved laterally into the passing row, and then the selected transport elements can be moved along the passing row in the direction of the removal area.

[0039] A specific object of the invention is a combination weighing machine including a system according to the invention.

[0040] The terms "a" and "one" are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the term. For example, "an element" means one or more elements.

[0041] Throughout this specification, the expression "which comprises" certain elements or operations, or variations such as "comprises" or "comprising," will be understood to imply the inclusion of these, but not the exclusion of other elements or operations.

[0042] Non-limiting embodiments of the present invention are illustrated in the drawings. [Brief explanation of the drawings]

[0043] [Figure 1] 1 is a perspective view of a system according to the present invention; [Figure 2] FIG. 2 is a schematic plan view of the work surface of the system of FIG. 1. [Figure 3] FIG. 2 is a side view of the system shown in FIG. 1. [Figure 4] FIG. 2 is a plan view of the system shown in FIG. [Figure 5] FIG. 2 is a side view of a conveying element of the system of FIG. 1. [Figure 6] FIG. 2 is a perspective view of a conveying element of the system of FIG. 1. [Figure 7] FIG. 6 is a cross-sectional view of the system taken along section AA in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0044] 1 shows a system 100 for assembling multiple items with a total weight within a specified range. The system 100 is suitable for integration into a production process, particularly a packaging process. More specifically, the system 100 implements a combination scale.

[0045] According to the embodiment shown, the system 100 comprises a type of platform 55 defining a working surface 5 substantially in a horizontal plane, on which a plurality of conveying elements 4 are movably arranged and are movable by levitation relative to the working surface 5.

[0046] In this example, the transport element 4 comprises a floating base 41 and a container 42 that is carried by the floating base 41 and is configured so that items can be loaded into it.

[0047] Apart from this example, in other variations not shown, it is envisaged that the floating base 41 may carry two or more containers, either the same or different.

[0048] The transport elements 4 of the system 100 move in a looped path on the work surface 5, passing through a loading area 6a where items are loaded into corresponding containers 42, a selection area 6b where N transport elements 4 with loaded containers 42 wait to be selected, and a removal area 6c where the selected n transport elements 4 gather around or near an item collector 3 so that the containers 42 can discharge the items loaded therein. Figure 2 shows a schematic arrangement of the loading area 6a, selection area 6b, and removal area 6c on the work surface 5.

[0049] The system 100 is designed to perform the functions of a combination scale or weighing machine. For this purpose, the transport elements 4 each perform the function of a weighing unit, obtain measured weight values ​​of the items loaded in their respective containers 42, perform a combination calculation based on the measured weight values, and select a combination of n transport elements 4 whose sum of the measured weight values ​​of the loaded items matches a target weight. In the system 100, the N transport elements 4 candidates to be part of this combination wait in a waiting area 6b of the work surface 5. The combination calculation is performed by a control unit 2 programmed for this purpose using known techniques.

[0050] As mentioned above, the conveying elements 4 together with the corresponding containers 42 are movable along the working surface 5 by levitation.

[0051] Various embodiments of technical solutions making it possible to control the movement of a conveying element along a working surface by levitation are described, by way of example only, in the patent documents WO 2021250077 "Method for controlling a planar drive system and planar drive system", EP 3868009 "A device and a method for path planning for a mover of a drive device" or EP 3818625 "Method for moving a rotor in a planar drive system".

[0052] Examples of commercially available products with transport elements that can move along a work surface by levitation are Acopos 6D from B&R Industrial Automation, Xplanar from Beckhoff Automation or Xbots from Panar Motor.

[0053] It should be noted that the technique of moving a conveying element along a work surface by levitation is a technique that gives the conveying element more than two degrees of freedom, since a spinning motion can also be transmitted to the conveying element (to rotate itself) for tilting relative to the work surface or for approaching and receding from the work surface.

[0054] In one way of applying these technical ideas to this case, the floating base 41 of each conveying element 4 defines a substantially flat underside facing the work surface 5 and is elevated a certain distance without contacting the work surface 5.

[0055] In this example, the floating base 41 has a square rectangular planar shape, although other shapes and configurations are possible, such as a shape that is self-enclosed leaving a central passageway.

[0056] In this example, all floating bases 41 have similar dimensions and the containers 42 have a similar planar shape to these floating bases, but other shapes and configurations are also possible, for example the system may combine floating bases of different dimensions and / or shapes and / or carry containers of different capacities, with the aim of having as part of the combination transport elements capable of carrying a heavier load of multiple items and transport elements capable of carrying a lighter load of multiple items. This last way, the combined weight can be fine-tuned to match the target weight, for example by taking into account the combination of transport elements whose weight of items is of the same order of magnitude as the target weight with transport elements whose weight of items is an order of magnitude smaller than the target weight.

[0057] In each case, the system 100 implements known solutions of the type that ensure magnetic induction interaction between the platform 55 defining the work surface 5 and each levitation base 41 of the transport element 4, allowing a levitation movement of the loaded or unloaded transport element 4 along and above the work surface 5.

[0058] The magnetic induction interaction as described above can be obtained by providing the platform with a plurality of individually excitable solenoids embedded in the platform 55 and distributed along the work surface 5, particularly embedded in the upper portion of the platform 55 adjacent to the work surface 5, and by providing permanent magnets embedded in the levitation base 41, so that the solenoids and permanent magnets are magnetically coupled to each other and magnetically interact with each other, causing levitation and movement of the conveying element 4 relative to the work surface 5.

[0059] More specifically, in use, the solenoid is polarized with a given current, generating (in a known manner) a magnetic field that causes the conveying elements 4, each carrying a permanent magnet, to be magnetically coupled to the solenoid and thereby levitated and moved above the work surface 5.

[0060] Furthermore, with regard to weighing, the system 100 of the present invention takes advantage of the features offered by known techniques of levitation transport, in particular with regard to correlating parameters of the magnetic inductive coupling between the platform 55 and each levitation base 41 of the transport element 4, not only to generate levitation movement of the transport element 4 along the work surface 5, but also to estimate the weight of one or more items loaded in one or more containers 42 of the transport element 4.

[0061] As an example, since the platform solenoid is energized with a given rated current to maintain the conveying element 4 at a predetermined non-zero distance from the work surface, the variation in the given current can be measured during or after the loading operation and correlated with the mass of one or more items loaded on the conveying element 4. The variation in the given current is increased to counteract the increasing tractive effect of weight on the mass of the assembly defined by the conveying element 4 and its load, in particular when attempting to maintain a predetermined distance between the conveying element and the work surface.

[0062] Some examples of proposals that take advantage of known levitation conveying technologies and in particular perform weight measurements of loads placed on conveying elements are described in the patent documents WO 2021115559, EP 3621902, EP 3440441 and WO 2022184517.

[0063] Returning to the details of the exemplary system 100, FIG. 2 shows that the work surface 5 has an essentially rectangular planar shape, the perimeter of which is defined by a first, straight, short side 5a and two straight, perpendicular long sides 5b and 5c to the first short side 5a.

[0064] The article supply section 1 is arranged on the first short side 5a (see Figures 1, 3 and 4), and is exemplified in the form of a supply section 1 comprising a bulk article storage section 11 from which extend a plurality of four article supply channels 12, the distal end of each channel ending in a loading area 6a on the work surface 5, below which a respective conveying element 4 is arranged to receive an article or a series of articles into a container 42.

[0065] The number of compartments 11 and the number of supply channels 12 per compartment may vary.

[0066] Likewise, it is envisaged that the supply unit 1 incorporates means for distributing the articles, which may be metering means, timer means or the like for enabling or disabling the supply of articles to the conveying elements 4 via the supply channel 12. The system 100 according to the invention is compatible with known technical solutions for regulating and / or controlling at least the number of articles supplied by the supply channel 12, in number or supply time.

[0067] In this example, the feed channel 12 is straight and extends in a direction perpendicular to the first short side 5a of the work surface 5. In this example, the work surface 5 extends sufficiently so that the conveying elements 4 can be sequentially positioned under the distal end of the feed channel 12 by forward movement in a direction parallel to the long sides 5b and 5c of the work surface 5 and towards the above-mentioned selected area 6b. This forward direction is indicated by arrow A1 in Figure 4.

[0068] In system 100, selection area 6b is sized so that the number N of conveying elements 4 spatially arranged thereon is greater than the number n of conveying elements 4 that are part of the total weight combination of items that matches the target weight, as will be described in more detail below.

[0069] In the system 100, the control unit 2 is programmed to execute the following instructions: at least adjust the movement of the transport elements 4 from the loading area 6a to the selection area 6b; as already mentioned, perform a combination operation to derive a combination of transport elements 4 located in the selection area 6b; adjust the movement of the transport elements 4 that are part of the combination from the selection area 6b to the removal area 6c, in particular until they are gathered around or in the immediate vicinity of the collection section 3, as shown by arrow A2 in Figure 4; ensure that the items loaded in the containers 42 of the transport elements 4 are discharged into the collection section 3; and adjust the movement of the transport elements 4 from the removal area 6c back to the loading area 6a, as shown by arrow A3 in Figure 4.

[0070] In the exemplary system 100, the spatial arrangement of the loaded transport elements 4 in the selection area 6b is a matrix arrangement, with waiting rows alternating with passing rows, in which column positions can be occupied by transport elements 4 waiting to be selected for combination, and into which the transport elements 4 selected for combination and waiting in the adjacent waiting row can first be moved laterally and then along said passing row in the direction of the removal area 6c. The passing rows are highlighted in Figure 4 by shading.

[0071] As regards the unloading area 6c, this is an area in which the conveying elements 4 of the combination can be arranged around or in the vicinity of a collection part 3, in this example in the form of a hopper opening above the working surface 5.

[0072] The shape and arrangement of the hopper relative to the work surface 5 may differ from that shown.

[0073] For example, in a variant not shown, the hopper may be arranged inside the periphery of the platform 55 that defines the work surface 5 , ie the hopper is surrounded by the work surface 5 .

[0074] In another variant not shown, the hopper may be arranged on one side of the platform 55 and its upper edge may be attached to the periphery of the platform 55 which defines the work surface 5 .

[0075] In another variation, the system has two or more hoppers.

[0076] In other variations, the collector may be different from a hopper, for example a conveyor belt.

[0077] In this example, the periphery of the platform 55 defining the work surface 5 in the unloading area 6c has a rectangular planar recess in which the hopper is recessed or, in any case, opens, the upper opening of the hopper may be equal to the opening of this recess or may extend beyond said rectangular recess, for example.

[0078] More specifically, in this example, the work surface 5 is symmetrical with respect to the longitudinal axis, and the recesses of the platform 55 are equidistant from the long sides 5b and 5c of the work surface 5. The periphery of the platform 55 defining the work surface 5 in the unloading area 6c can in this case be defined by a U-shaped sector, in which two parallel and linear unloading openings are provided, which can be used alternately by the combination of n conveying elements 4 in two successive combined weighing operations to unload the loaded articles.

[0079] This special shape of the work surface 5 makes it possible to increase the number of pick-up operations per unit of time, since while n conveying elements 4 are picking up articles occupying the space of a first pick-up outlet, another n conveying elements that are part of a subsequent combination can move towards and / or be aligned with a second pick-up outlet. This special situation is shown in practice in Figures 1 and 4.

[0080] In the example of system 100, receptacle 42 is tipper 44. In this case, tipper 44 is articulated to floating base 41 about axis 43, all as shown in Figures 5 and 6.

[0081] Shapes or configurations other than those shown in the drawings are also possible. For example, it is conceivable that one or more tippers may be mechanically connected to the corresponding floating base by means other than an articulated connection. Any mechanical solution that allows the tipper to be moved relative to the floating base should be considered in order to ensure tipping and the ejection of the items contained in the item collector 3.

[0082] In other variations, the entire conveying element 4 can be tilted, causing the corresponding container 42 to dispense its contents. For example, a portion of the platform 55 can be a movable, rotating portion, which rotates to rotate the floating conveying element relative to the area of ​​the work surface 5 defined by this movable portion of the platform. The movable portion of the platform 55 can be the portion defining the outlet, and the container 42 can be fixed relative to the corresponding floating base.

[0083] In this example, the tippers 44 of the conveying elements 4 of the system 100 are dimensioned relative to the outlets so that the tippers 44 of two or more conveying elements 4 can be lined up and discharge contents into the collection section 3 simultaneously from the same outlet.

[0084] Actuating one or more tippers 44 of the conveying element 4 from the conveying position to the tilting position can be carried out by equipping the conveying element 4 with its own actuating means, for example, but not limited to, electrical or pneumatic means.

[0085] However, in the illustrated system 100, the tipper 44 is actuated in its tilting motion by an external mechanism.

[0086] For this purpose, the removal area 6c is equipped with two tilting mechanisms 8, each of which, by mechanical connection with a tipper 44, can ensure simultaneous tilting and ejection of the articles contained in the tippers 44 of the n conveying elements 4 that are part of the combination and are aligned at the removal opening in this example.

[0087] To create a mechanical connection, the tiltable mechanism 8 and the tipper 44 comprise complementary means of interconnection, such as, for example, a connecting lug 45 on the tipper 44 and a rail 81 on each tiltable mechanism 8, which is oriented parallel to the work surface 5 and is securely attached to a rotating arm 82 about an axis 83 oriented parallel to said work surface 5. Each rotating arm 82 is controlled by the control unit 2 and can rotate between at least two positions: one is a connecting position A, which positions the rail 81 within the reach of the connecting lug 45 of the tipper 44, and the lug 45 of the tipper 44 of the n conveying elements 4 aligned at the outlet can be inserted into the rail 81 through the first end 81a of the rail; and another is a tilted position B, in which the tipper 44, with its connecting lug 45 inserted into the rail 81, is tilted and rotates about the rotation axis 43 for connection with the corresponding floating base 41. From the tilted position B, the rotating arm 82 is rotated back to the coupled position A, allowing the n transport elements 4 to be decoupled from the rail 81 when the alignment of the n transport elements 4 advances towards the second end 81b of the rail 81. The decoupling or removal of the rail 81 allows for the new alignment of the n transport elements 4 to be accommodated and removed.

[0088] The details of Figure 7 show the rail 81 of the tilting mechanism 8 and, on the right side of the image, the rotating arm 82 of the rail 81 of the tilting mechanism 8 in the connected position A, and, on the left side of the image, the rotating arm 82 of the rail 81 of the tilting mechanism 8 in the tilted position B.

[0089] Advantageously, the movement of the tipper 44 provides a constant thrust to the articles, further increasing the discharge speed, i.e. the rate at which the articles are released through the collection section 3, compared to solutions where, for example, removal of the articles occurs by opening a gate or hatch at the bottom of the container.

[0090] An example of how the system 100 operates in accordance with the present invention is summarized below.

[0091] The conveying element 4 is actuated to move over the working surface 5, the cycle of the conveying element 4 comprising: - a movement to circulate through the loading area 6a and position the tipper 44 under the article supply channel 12 to receive the articles; - moving the tipper 44 loaded with articles to the selection area 6b; - measuring the weight value of the article loaded on the tipper 44 either at the end of loading, during movement to the selection area 6b, or while the tipper 44 is dwelling in the selection area 6b; - there is a possibility of moving it to occupy another cell of the matrix within the selection area 6b, when it is deemed appropriate to rearrange the transport element 4 within the selection area 6b when it leaves this selection area 6b to become part of a combination and goes towards the removal area 6c, and when a new transport element 4 with a new load of articles arrives at the selection area 6b from the loading area 6a, - if the article weight is part of a combination that forms a total weight that matches the target weight, it moves from the selection area 6b to the outlet of the removal area 6c and aligns itself with at least n-1 other conveying elements 4 that are part of the same combination in article weight, said movement including the conveying element 4 spinning, i.e. rotating by 90°, and positioning itself so that its coupling lugs 45 can be inserted into and coupled to the rails 81 of the tilting mechanism 8 of the outlet; - tilting of the tipper 44 by actuation of the tilting mechanism 8; - movement of the tilting mechanism 8 from the guide 81 in the same direction as when it was connected, in order to uncouple it; and - a movement back to the loading area 6a to start a new cycle, in this case circulating along the side edge of the working surface 5 provided to facilitate the circulation of the transport elements from the unloading area 6c to the loading area 6a.

[0092] Naturally, other alternative movement schemes may be adapted to suit the production requirements of the system, other arrangements and / or configurations of the supply and / or collection sections, a number of candidate conveying elements different from N for combination, a number of conveying elements other than the maximum n for combination, different shapes of conveying surfaces, the fact that combinations of conveying elements have different sizes and / or numbers of containers per conveying element, the type or nature of the goods to be weighed, or any combination of the above.

[0093] As known to those skilled in the art, in a combination scale, the average number of metering units selected for combination will vary depending on the model of the scale and the speed required.

[0094] The appropriate average number of weighing units is 4 to 6 for conventional combination scales that require less than 60 weighings per minute, and this average number is 3 to 4 when more than 60 weighings per minute are required. If the average number of weighing units required to find a combination whose item weight values ​​meet the target weight is outside these ranges, the speed of the scale will be affected.

[0095] The system 100 according to the present invention can operate with a higher average number of weighing units than conventional combination scales, if desired, without affecting speed, i.e., the number of weighing units per minute. In one example, the system 100 can be operated with an average number of selected weighing units greater than four to find a combination whose weight value meets the target weight, and the system 100 can perform more than 60 weighings per minute.

[0096] The system 100 according to the present invention can operate with the same average number of weighing units as a conventional combination scale, and outperforms the conventional combination scale in terms of speed.

[0097] In the example of the drawings, the system 100 can operate to select up to n=4 transport elements 4 from the parks of N=22 transport elements 4 in the selection area 6b that are candidates to be part of the combination in order to find a combination in which the weight values ​​of the items meet the target weight, meaning that there are a total of 7,315 possible combinations, whereas in a conventional combination multi-level weighing machine there are typically a total of 14 candidate parks (including weighing units and spare drawers), and the number of possible combinations is 1,001.

[0098] Of course, in addition to performing combination calculations based on the measured item weight values ​​and selecting a combination of conveying elements whose sum of the measured loaded item weight values ​​matches the target weight, the control unit 2 may be programmed to perform other calculations or to take into account aspects other than item weight in determining the combination, such as size or the nature of the particular item. For example, a package may require that an accompanying prize or item be added to the package in addition to the weight of the food item to meet the target weight. The control unit knows which conveying elements 4 have prizes placed on them and, for example, how often the prize needs to be added to the package in order to make these conditions part of the calculation logic.

[0099] Other important advantages of the system according to the invention are: - Replacing the weighing unit is easy and simple, requiring only the exchange of one conveying element for another, since there are no mechanical connections with the rest of the system and no spare trays to be fed from the weighing unit. When handling fragile items, the system eliminates the shocks that items experience when moving up and down between the preload drawer, weighing unit, and reserve drawer in a conventional combination scale. - The height required for the collection area to discharge the items into the container is significantly reduced, as this eliminates the need for a concentric arrangement of the weighing units, which would distance the weighing units that are part of the combination (or the spare drawer placed one level below), which would require the collection area to have a vertical dimension due to the distance required to maintain a minimum inclination of the collection area, which would slow down the discharge speed (affecting the preservation of fragile items). - Reduced noise during operation, especially for bulk goods such as nuts, due to the absence of cascading drops between the levels of the combination scale (preload drawer, weighing unit, and spare drawer). - Easy to clean and maintain hygiene. - Weight values ​​are obtained quickly. - Easy access to components or moving parts. The space required by the system is significantly reduced compared to conventional combination weighers, especially in terms of height. - It is versatile, allowing the number of conveying elements and therefore weighing units to be increased or decreased on the same platform without changing the operations carried out in the loading and unloading areas. - It may incorporate intermediate work stations at which the conveying elements can advance and / or stop during their movement, or it may incorporate auxiliary stations, for example cleaning or sterilizing stations, such as by blow-cleaning or rinsing, arranged in the path taken by the conveying elements 4 from the unloading area 6c to the loading area 6a.

Claims

1. 1. A method for collecting a plurality of items at a target total weight, comprising the steps of: supplying the items to a plurality of weighing units to obtain measured weight values ​​of the items; performing a combination operation based on the measured weight values ​​to select a combination of these measured weight values ​​whose sum matches the target weight; and collecting the items of the weighing units whose measured weight values ​​are part of the combination, wherein the weighing units are transport elements movable by levitation relative to a work surface and capable of following different trajectories between at least two areas of the work surface, one of which is a loading area where the items are supplied to the weighing units and another of which is an unloading area where the weighing units that are part of the combination discharge their contents into at least one item collecting section.

2. 1. A system (100) for collecting a plurality of articles with a target total weight, the system (100) comprising: a supplying section (1) of articles to a plurality of weighing units to obtain measured weight values ​​of the articles; a control unit (2) programmed to perform a combination operation based on the measured weight values ​​and to select a combination of these measured weight values ​​whose sum corresponds to the target weight; and at least one collecting section (3) for the articles supplied to the weighing units whose measured weight values ​​are part of the combination, characterized in that the system is characterized in that the weighing units are transport elements (4) movable by levitation relative to a work surface (5) and capable of following different trajectories between at least two areas of the work surface (5), one of which is a loading area (6a) where the supplying section (1) supplies the articles to the transporting elements (4), and another of which is an unloading area (6c) where the transporting elements (4) that are part of the combination discharge their contents into at least one article collecting section (3).

3. 3. The system according to claim 2, characterized in that the work surface (5) is a horizontal or substantially horizontal surface, the transport element (4) comprises a floating base (41) and at least one container (42) carried by the floating base and suitable for the supply section (1) to load items in the loading area (6a), and means are provided for discharging the items into the at least one item collection section (3) in the removal area (6c).

4. 4. A system according to claim 3, characterized in that the means for discharging the articles comprise a movable part of a work surface (5) in the unloading area (6c).

5. 5. A system according to claim 3 or 4, characterized in that said at least one container (42) is a tipper (44).

6. 4. The system according to claim 3, characterized in that the at least one container (42) is a tipper (44) and the means for discharging the articles comprise, in the removal area (6c), at least one tilting mechanism (8), the mechanical connection of which with the tipper (44) ensures the tipping of the tipper and the discharge of the articles contained therein into at least one article collection section (3).

7. 7. The system according to claim 6, characterized in that the tilting mechanism (8) and the tipper (44) comprise complementary means for interconnection, and the tilting mechanism (8) is configured to be simultaneously connected to the tippers (44) of two or more conveying elements (4), thereby ensuring the tilting operation and the ejection of the articles contained in the tippers (44) of two or more conveying elements (4) into the article collecting section (3).

8. Said complementary means of interconnection are: A tipper (44) has a connecting projection (45), a rail (81) of the tilting mechanism (8), the rail (81) being oriented parallel to the work surface (5) and securely attached to a rotating arm (82) between at least two positions around an axis (83) oriented parallel to the work surface (5), one of the two positions being a coupling position A, in which the rail (81) is positioned within the reach of the coupling protrusions (45) of the tippers (44), allowing the coupling protrusions of the tippers of two or more conveying elements moving on the work surface (5) to be inserted into the rail (81) through the first end (81 a) of the rail, and another being a tilting position B, in which the protrusions tilt the tippers inserted into the rail; The system of claim 7, comprising:

9. 9. The system according to claim 2, wherein the work surface (5) comprises at least one outlet formed by an edge region of the work surface (5), at which a plurality of conveying elements (4) that are part of a combination can be gathered and the articles in their containers (42) can be discharged into an article collection section (3).

10. 10. The system according to claim 9, characterized in that the edge region is a peripheral region, i.e. a peripheral region of the periphery or contour of the working surface (5).

11. 10. The system according to claim 9, characterized in that the edge area is an inner edge area, i.e. an inner edge area of ​​the periphery or contour of an opening in the working surface (5).

12. A system according to any one of claims 2 to 11, characterized in that said at least one article collector (3) comprises a hopper.

13. 13. The system according to claim 2, wherein the work surface (5) comprises a substantially coplanar selection area (6b) dimensioned to spatially arrange on the selection area (6b) a number N of transport elements (4) greater than the number n of transport elements that are part of the combination, and wherein the control unit (2) is programmed to coordinate the movement of the transport elements (4) in a loop from the loading area (6a) to the selection area (6b), from the selection area (6b) to the unloading area (6c) and from the unloading area (6c) back to the loading area (6a).

14. 14. The system according to claim 13, characterized in that the spatial arrangement in the selection area (6b) is a matrix arrangement, in which waiting rows, in which column positions can be occupied by transport elements (4) waiting to be selected as part of a combination, are arranged alternately with passing rows, into which transport elements (4) selected as part of a combination and waiting in a row adjacent to the passing row are first moved laterally, and then the selected transport elements (4) can be moved along the passing row in the direction of the removal area (6c).

15. A combination weighing machine comprising a system (100) according to any one of claims 2 to 14.

16. Use of a conveying element (4) movable by levitation relative to a substantially flat work surface (5) as a weighing unit in a combination weighing machine, wherein the conveying element (4) movable by levitation is movable between an article supply section (1) to the conveying element (4) and a collection section (3) for the articles supplied to the conveying element (4).

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