NL1022801C2 - Conveyor device for weighing objects, especially foodstuffs, has upper run of belt extending around end guide movable against belt in order to tension it - Google Patents

Abstract

The upper run of the endless conveyor belt (1) extends around two end guides (2, 3) which are movably mounted in the fixed frame (4) for the sorting device. One end guide can be moved into a position where it presses against the belt in order to create tension in the belt run above it, the tension being independent of the belt weight. The return run of the belt is supported over substantially the entire transport length. The conveyor belt is used to move a number of objects supported by its upper run over a weighing device (11).

Description

Device for automatically sorting or weighing objects on a conveyor belt by weight.

The invention relates to a device for automatically weighing fixed or flexible objects of any size and shape, comprising an endless flat conveyor belt with an upper part and a receding part, which is provided to be driven to run over a weighing device to move a number of objects located on the upper part.

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More specifically, this invention relates to a device in which objects are placed on a conveyor belt for the purpose of weighing them and possibly removing them according to their weight class at well-defined fixed locations along this belt in order to achieve a weight sorting. In particular, this applies to the weighing and sorting in the food industry of fish, fish fillets, crustaceans, fruit, vegetables or meat products.

This invention also applies to products that are supplied in bulk, in a continuous mass, as is the case, for example, with shrimp. In this patent application the word "objects" is therefore also used in that sense.

The known sorting devices always consist of three functional parts; arranged one behind the other and containing one or more conveyor belts.

The first part, the feeding part, is provided for receiving and accelerating the objects that are supplied manually or automatically. The second part, the weighing part, consists of an endless belt, which either runs over one or more weighing plates with each weighing plate forming part of an electronic or mechanical scale carried out according to known techniques, 1022801 2 or of an independent frame arranged together with its drive and where the total system is weighed.

The third part, the sorting part, consists of a conveyor belt of a certain length, wherein at certain distances from the beginning of the belt one or more fixed devices are provided for removing the objects from the belt.

A computer determines according to the weighted weight class of the object when a certain device must take action to remove the object from the tire. Thus, all objects of the same weight class are placed in the same place in e.g. a container or some device for further processing.

These existing devices comprise three different conveyor belts, each with their own drive, so that each of the above-mentioned functional parts comprises a separate conveyor belt. These devices are characterized by the special design of their weighing section.

In other words, this weighing part (according to patent WO 99/36753) is provided with a thin, running weighing belt hanging loose in the lower part, so that the weight of this belt gives a very small influence on the precision of the weighing. This belt contains a series of perforations on both sides which are carried along by gears on the sides of a drive roller. Because of these perforations, this thin belt is wear sensitive and has a very limited strength. This tire only absorbs small axial forces. As a result, it is mandatory to arrange the feed section and sorting section separately, since the bands of these sections must absorb relatively large axial dynamic forces for accelerating and ejecting the objects.

Since this thin weighing belt wears out relatively quickly, it is mandatory to regularly renew this expensive belt.

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Or, together with its drive, the weighing belt is set up on an independent frame, whereby the total system "frame with belt and drive" is weighed. This means that the feed section and the sorting section must each be realized by a separate conveyor belt.

The accuracy of the weighing is also adversely affected by the relatively large mass of the total system relative to the object to be weighed; in particular when this device is arranged on a seagoing vessel subject to up and down movements due to stamping and rolling of the ship.

The patent applications WO 99/36752 and WO 99/36753 also describe devices in which the weighing part is realized by an endless belt. The assembly line exists e.g. from a modular plastic strap. The upper part of this relatively heavy belt runs over a permanently arranged weighing unit while the lower receding part of the belt is supported, with the aim of eliminating the weight and the vibrations of the belt in order to minimize the belt pressure at the weighing unit. and to keep it constant. With these devices, the influence of the weight and the vibrations of the tire can only be partially eliminated. Indeed, in order to prevent the tire from coming loose and shockingly coming up, a minimum tensile force is required in the tire, in particular at the location of the run-off side of the driven roller at the beginning of the support. This minimum tensile force must be achieved here by allowing part of the receding part to hang loose; namely the rising part to a final roll; wherein the weight of this part forms a chain line with a tensile force which must at least be equal to the friction of the still supported part of the receding belt. For this purpose, the length of the hanging part must be at least a quarter of the supported length, ie. the tire will leave any longer support at this length. Due to its weight, this loose-hanging part is subject to vibrations and oscillations, which change into tension changes from the top of the belt running across the weighing unit. As a result, the weighing accuracy is negatively influenced and this is problematic when setting up one long belt, also used for supplying and / or sorting the objects.

All the more so since, in the arrangement according to these patents, the tire pressure at the location of the weighing plate is still relatively large due to the friction on the support of the lower receding tire and the weight of the hanging part of the tire. In addition, a change in these frictions causes a change in the weighing result.

This principle has the important limitation that it is not usable on board a ship there, because of the stamping and rolling of the ship, the changes and delays in all directions of the underlying belt and the associated mass forces, the chain line of the loose hanging part constantly and uncontrolled in shape and length changes with the resultant variations in the belt tension at the location of the weighing plate, and thereby deviations and poor accuracy of the weighing result.

In "Patent Abstracts of Japan publication n ° 10167441" a principle is shown for the lateral belt control of a thin endless belt, whereby the turning elements are provided as knife edge transitions, via a fully automatic control mechanism.

The belt tension is determined by a movable roller that is placed in a fixed position by an immovable element, e.g. a line screw. In this element, the clamping force is set indefinitely and not automatically to a certain value. A change in band length results in an indefinite change in tension in the band. Here too, the underside of the receding parts of the belt is not supported, with the same disadvantages as described above with regard to the devices according to patent applications WO 99/36752 and WO 99/36753. The belt tension at the location of a weighing unit is also 1022801 dependent on the weight and the dynamic behavior of the hanging belt sections.

There are also machines that supply, weigh and sort with one running 5 belt system. Examples of this can be found in the patents EP 0 060 013 and EP 0 283 388.

The limitations of these machines are based on the nature of the product.

EP 0 060 013 describes a system with trays that can two chains are moved. This system is economically much more expensive to realize than a flat conveyor belt and falls outside the scope of this invention. This construction is less suitable for use at sea as the weight of the trays is large in relation to the small weight of, for example, fish and thus makes the compensation of the accelerations of the whole less accurate. Weighing a continuous medium is also impossible.

EP 0283388 discloses a machine that can transport round, small and solid products such as fruit, between two conically arranged conveyor belts with a certain intermediate opening. The product is weighed by a wheel positioned between the tires and thus the product is lifted off the tires as it passes through this wheel. The use of slack products with large variation in dimensions and shape 20 is not possible.

The object of the invention is to eliminate all of the aforementioned disadvantages and to obtain an accurate weighing, also on a sea-going ship, with a relatively heavy and wear-resistant conveyor belt.

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This object is achieved by means of a device for automatically weighing objects of any size and shape comprising an endless conveyor belt; with an upper part bounded by 2 end elements mounted in a fixed frame, and an underlying receding part that is supported at least partially by 10, wherein the conveyor belt is provided for being driven to run over a weighing device a number on the upper part moving located objects, while at least one of the end elements is arranged movably in the frame, and the device is provided to press a movable end element in such a direction that the belt is tensioned so that a belt tension is obtained in the upper portion that is independent of the belt weight, and while the receding portion of the conveyor belt is supported over substantially the full conveyor length.

As a result, the influence of the tape weight on the tape tension can be switched off, so that it can be set small, which consequently increases the measurement accuracy.

The belt is for instance provided with an elastic clamping under a well-defined and possibly constant force, as a result of which the belt tension at the location of the weighing unit is controlled completely independently of the belt weight (for example to a minimum value). This eliminates the influence on the tire pressure of the tire weight and the mass forces of this tire (caused by the up and down movements on a seagoing ship).

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These characteristics make it possible to perform the functions, feeding, weighing and sorting combined with a single long conveyor belt. With a single conveyor belt it becomes possible to sort articles that have an adhesive adhesion on the belt, such as fish fillets, on the same belt by weight; which is problematic in the arrangement of two successive conveyor belts due to the transition from one conveyor belt to the next.

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Moreover, the construction of one combined weighing, feeding and sorting belt with only one drive, compared to the existing devices with two or three belts and drives, can be realized and maintained much more economically.

By applying a further feature of this invention, it is even possible to also largely eliminate the influence of the friction of the tire and the load changes on it when the objects are dropped, so that the highest possible precision of the weighing is obtained. is going to be.

The pressure element is preferably an elastic element or an element which is provided for exerting a constant and adjustable force.

Further features of this invention were mentioned in claims 3 to 7.

In order to better explain how the object of this invention is achieved by applying its features, Figures 1, 2, 3, the arrangement of which can only be considered as an example of a possible embodiment, while all other possible embodiments that meet the characteristics of the claims, however, also fall within the scope of this invention.

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Fig. 1 shows the schematic representation of the side view in section of the mechanical arrangement according to claim 1, of a combined conveyor belt; for feeding, weighing and sorting the applied objects.

Figure 2 shows the plan view of the above arrangement.

FIG. 3 shows the schematic representation of the side view in section as described above but with a specific arrangement according to claims 2 and 3.

The proposed device according to Figs. 1 and 2 consists of an endless conveyor belt (1), running over two end rollers (2), (3) which are mounted in bearings in the side plates of a fixed frame (4). Optionally, one or more rollers (5) are provided at a specific location to increase the space under the belt at local locations for the installation of e.g. weighing equipment and sorting equipment. One of the roles, for example. the end roller (2) is driven by a motor (6). Two rolls 5 e.g. the end roll (2) and the roll (5) are mounted in solidarity in the frame, while e.g. another roller (3) is provided with 2 bearings (7) which are arranged horizontally in the side plates of the frame. By controlling this horizontal movement, the conveyor belt is more or less tensioned. The upper part of the conveyor belt is supported along its entire length by horizontal plates (8), (9), (10). The 10 plates (8) and (10) are connected jointly to the frame, while the plate (9) forms part of an electronic or mechanical weighing device (11). Furthermore, as an example of a specific discharge system, one or more horizontally hinged valves (12) are provided which are arranged at fixed locations along the belt. According to an inventive feature, on the one hand, the lower receding portion of the belt (1) on the underside is entirely supported by e.g. two guide slats (14) arranged to receive the full weight of the hanging part.

On the other hand, e.g. the horizontally sliding bearings (7) of the return roller (3) each through an elastic element, e.g. a spring (15) loaded radially; the spring tension e.g. can be adjusted by means of a clamping screw (17) with a nut (16) which is fixed to the frame in solidarity. The tire pressure is hereby adjusted to a specific force, wherein the elastic element automatically absorbs the changes in length of the tire due to temperature, wear or humidity.

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The above-mentioned elastic element can also be a pneumatic or hydraulic cylinder under constant and / or adjustable pressure; or any other elastic system. When weighing and sorting a series of individual objects, eg fish or fillets, these are placed one after the other at the start of the feeding portion of the belt 10228 01 9 above the plate (8), at a mutual distance determined by the length of the weighing plate ( 9) installed automatically or manually. The fish is accelerated up to the belt speed along the length of the plate (8). After this acceleration, the fish is pushed on the belt over the weighing plate (9) at a constant speed. After the weighing, the fish lands on the sorting section of the belt above the plate (10). Here, according to the known methods, by controlling a computer, the fish are dropped according to their weight class through one of the valves (12) in a container (13). Only the fish of the same weight class are collected per container.

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Fig. 3 contains the same elements with an alternative arrangement according to the features of claims 2 and 3, wherein the roller (5) is arranged at a specific location and the drive by the motor (6) here takes place on the roller (5) or (3).

The object of this invention relates to the elements of the mechanical arrangement of the conveyor belt as such, characterized in that it supports, for example, the otherwise loosening lower receding portion of the conveyor. the guide slats (14) in cooperation with the elastic tensioning of this band by the springs (15).

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The accuracy of the weighing depends on the internal friction of the belt which is dependent on the tensile stress at the location of the weighing unit, this is because the belt must sag slightly at the transition of the plate (8) to the weighing plate (9) ; and rising from the weighing plate (9) to the plate (10).

It is therefore important to keep the tensile stress on the weighing unit as small and constant as possible, thus independent of the weight, the load changes and the mass forces of this belt.

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In contrast to other existing devices, according to a feature of this invention, on the one hand, the lower receding portion of the belt is supported along the full length along the bottom slats by the guide slats (14) such that the influence of the weight is completely switched off and the belt nowhere hangs loosely, and on the other hand the conveyor belt stretched to a specific force, e.g. by means of elastic elements (15). These elements are adjusted to a minimum force only needed to overcome the friction of the top of the tire; with the condition that the minimum tensile force in the tire at the outlet side of the drive roll (2) remains greater than 0. The weighing plate (9) 10 is then positioned as close as possible to this zone where the tensile force in the tire is minimum. Thus, the tensile stress at the weighing unit becomes small and completely independent of the tire weight, and in the proposed arrangement only determined by the clamping force in the top of the tire minus the friction of the tire on the top plate (10). With a coefficient of friction of 0.1, the tensile stress hereby becomes 10 times smaller than in the existing systems where this tensile stress is caused by the own weight of a non or partially supported tire. In summary, now the tensile stress and tensile stress changes in the conveyor belt, at the location of the weighing plate (9), are greatly reduced and much less dependent on the belt weight and the movements at sea, i.e.. only dependent on the friction of the tires, resulting in a much better weighing precision.

According to a second feature of the invention, an end roll or underlying roll is used as the driving roll wherein it is arranged so that the tape is bent by this roll through an angle of 90 ° and wherein this roll is arranged so as to be displaceable in a direction parallel to the ascending or descending belt.

According to a further inventive feature and according to Fig. 3, the roller (5) is fixedly arranged as a driving roller, more or less vertically below the movable end roller (3). The roller (3), loaded by the elastic elements (15), is also displaceable in a direction parallel to the upper belt.

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According to both of the aforementioned features, the tensile force in the band part, running parallel to the direction of displacement, where it leaves the displaceable roller, becomes in principle identical to the force of the elastic elements pressing in the direction of displacement.

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In the arrangement according to Fig. 3, the tensile force in the upper belt above the weighing unit (11) is here only determined by the bias of the elements (15) and the friction on the relatively short plate (8). This tensile force, in contrast to the arrangement according to Fig. 1, is independent of the friction of the tire on the guides (14), and the plate (10), and independent of the loads on the upper tire when being cast by the valves (12) of the sorted items. According to the specified driving direction of the tire, the pulling force is regulated here on the loose part of the tire where the pulling force in the tire is minimum.

The force of the elastic elements (15) is therefore only necessary so that the belt would not come loose when the driven roller (5) comes off, and can be set very small. As a result, it is achieved that the tensile stress of the tire above the weighing unit becomes as low as possible and is substantially constant, independent of the coefficient of friction of the tire across the guides and independent of the change in friction due to weight variations of the tire when placed on a tire. rolling and stamping seagoing ship. A moving ship can also cause mass forces in the longitudinal direction of the belt, as long as these mass forces are smaller than the friction of the belt, only the short belt part above plate (8) has an influence on the tensile stress above the weighing unit and thus on the weighing. In order to absorb larger mass forces, the friction of the belt at the location of the plate (10) can be increased by additional means.

In summary, we can say that the embodiment according to Fig. 3 has very great advantages in terms of precision of the weighing compared to. the embodiment according to fig.l.

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Since the weight and the friction of the tire no longer have any influence on the precision of the weighing, it is therefore possible to use relatively thick, modular and wear-resistant tires and to design these tires for such a long time that one tire performs all functions: power supply, weighing and sorting.

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The automatic tensioning of the conveyor belt by, for example, an elastic element has the advantage that the tension in the belt remains constant in the case of changes in the length of the belt caused by different influences. Thus, adjustment is no longer necessary, while the adjustment of the tension in the belt does not have to be carried out precisely, e.g. a relatively large rotation of the screw (17) causes a small change in the tire pressure 1022am

Claims (7)

An apparatus for automatically weighing objects of any size and shape, comprising an endless conveyor belt (1) with an upper portion bounded by 2 end elements (2), (3) mounted in a fixed frame, and an underlying receding portion that is at least partially is supported, wherein the conveyor belt (1) is provided for being driven to move, over a weighing device (11), a number of objects located on the upper part, characterized in that at least one of the end elements (2), (3) ) is arranged so as to be movable in the frame, and that the device is provided to press a movable end element (3) in such a way that the band is tensioned, so that in the upper part a band tension is obtained which is independent of the band weight, and that the receding portion of the conveyor belt is supported over substantially the full conveyor length. Device for automatic weighing of objects according to claim 1, characterized in that the pressure element (15) is an elastic element or an element which is provided for exerting a constant and adjustable force. Device as claimed in claim 1 or 2, characterized in that an end roll or underlying roll is driven, and that said movable roll tensiones the conveyor belt in the zone where it leaves the driven roll. 25 Device for automatic weighing of objects, according to one of the preceding claims, characterized in that an end element or underlying roller is used to drive the belt, and it bends the belt with an envelope angle of approximately 90 °, and below a certain force displaceable 1022801 is arranged in a direction more or less parallel to the ascending or descending belt. Device for automatic weighing of objects, according to one of the preceding claims, characterized in that at least one end element (3) is arranged so as to be movable under a certain force in a direction which is substantially parallel to the ascending or descending belt and wherein the belt is driven by an underlying roller (5), which is arranged substantially below said end element (3), whereby a constant belt tension independent of the belt weight in the upper part of the belt (1) at the weighing unit (11), of the tire load and the friction of the tire. Device for automatic weighing of objects, according to one of the preceding claims, characterized in that this device is provided for automatically sorting these objects by weight, the upper part of the conveyor belt (1) having the necessary length to hold a plurality of fixed sorting discharge devices arranged one behind the other. Device for automatic weighing or automatic sorting of objects, according to one of the preceding claims, characterized in that the upper part of the conveyor belt (1) is provided for realizing the supply and acceleration of the objects. 022fin.