WO2003045591A1

WO2003045591A1 - Method and device for grading objects

Info

Publication number: WO2003045591A1
Application number: PCT/IS2002/000020
Authority: WO
Inventors: Egill Thor Ragnarsson
Original assignee: Style Ehf.
Priority date: 2001-11-29
Filing date: 2002-11-29
Publication date: 2003-06-05
Also published as: EP1458500A1; AU2002353489A1; IS7273A

Abstract

The present invention relates to a method and device for grading objects according to at least one characteristic property of the objects. The method comprising feeding at least one separating unit with an upward facing inlet and a downward facing outlet moving with constant speed with objects following a first path with at least one characteristic property. By utilizing that said at least one separating unit reacts on the objects with friction force of different size depending on the characteristic property of said objects, wherein objects flowing through the outlet of said separating follow at least one second path that is characteristic for at least one characteristic property of said objects, wherein objects following each path are collected together.

Description

METHOD AND DEVICE FOR GRADING OBJECTS

Field of the invention

The present invention relates to a method and device for grading objects according to at least one characteristic property of the objects.

Background

The grading of objects such as fish and marine species such as capelin and herring can be a difficult task. The reason being their small size and the volume to be processed at each time combined with that the quality of fish deteriorates quickly if not stored at sub zero temperature. The grading therefore has to be highly efficient. The purpose of the grading is primarily to separate the species by size and/or sex. Such grading can often result in substantial increase in value as female capelin filled with eggs is much more valuable than the male species. No feasible methods are currently known for such grading.

There are machines, which are capable of grading fish and other objects by size, especially thickness. These include belt and roller machines of various types and shaker graders. The best known, are belt machines, which pull the object between two slanting belts which form a transport channel. These machines frequently have many channels. There are also roller machines where two or more parallel rollers from lanes slanting in the direction of movement of the object. The rollers rotate and the object moves forward. The distance between the rollers is greater at the output end than the input end so that the smallest units of objects are first to fall between the rollers while the larger units fall late. In this way, grading by thickness corresponds to increased distance between the transport belts and rollers. This applies generally to machines based on designs where the distance between lanes is greater at the out-feed end than the in-feed end.

The problem with such machines is that they grade only after the size of the product, but not the sex, which would increase the value of the product. Capelin as an example can consist of a female capelin filled with eggs, asexual capelin and male capelin. The female capelin is however much more valuable than the male and the asexual capelin. Description of the invention

It is an object of the present invention to provide a grading mechanism that can grade the products after at least one characteristic property, such as the sex of the object, which increases the value of the product.

According to the first aspect the present invention relates to a method for grading objects according to at least one characteristic property, said method comprising:

• feeding at least one separating unit with an upward facing inlet and an outward facing outlet moving with constant speed with objects following a first path with at least one characteristic property,

• utilizing that said at least one separating unit reacts on the objects with friction force of different size depending on the characteristic property of said objects,

wherein objects flowing through the outlet of said separating unit follow at least one second path that is characteristic for at least one characteristic property of said objects, wherein objects following each path are collected together.

In one preferred embodiment the object is capelin consisting of a female capelin filled with eggs, asexual capelin and male capelin. The characteristic property is in this preferred embodiment the different stiffness of the capelin, wherein the female capelin filled with eggs is much softer than the asexual and the male capelin. Also, the surface of these are different, which is mainly distinguished in the brushes that the male capelin has. However, the product can be of any kind, wherein characteristic property such as mentioned here are used to separate the product. Preferably, the objects that are fed to the separating unit have already been sorted after their size, i.e. the feeding objects are of the same size consisting of female, asexual and male capelin. When the objects touch the separating unit, a friction fore acts between the walls of the separating unit and the capelin due to the movement of the separating unit, depending on the sex of the capelin. This friction force is lowest when the capelin is female capelin filled with eggs and highest when the capelin is male. Accordingly, the first path that the product, which we assume that is capelin, that follows only one path before entering the separating unit is divided in up to three paths when after the capelin has been interacting with the separating unit due to the friction force. These different types can therefore be collected, so the capelin or any other product has be graded after their size and sex.

According to the first aspect the present invention relates to a device for grading objects after at least one characteristic property comprising:

• means for transferring objects with at least one characteristic property,

• at least one separating unit moving with constant velocity with an upward facing inlet for receiving said objects and an outward facing outlet for returning said objects, wherein said at least one separating units reacts on the objects with a friction force of different size depending on said at least one characteristic property,

• conveying means for conveying said at least one separating unit, and

• at least one bin positioned under said at least one separating unit for receiving the returning objects,

wherein different friction force between the objects and the separating means direct the object after at least one path, each path being characteristic for at least one characteristic property.

Detailed description

In the following the present invention, and in particular preferred embodiments thereof, will be described in greater details in connection with the accompanying drawings in which

Fig. 1 shows one embodiment of the grading system, Fig. 2 shows one embodiment of size sorting device, and

Fig. 3 shows a closer view of a single separating unit,

Fig. 4 shows a plurality of separating units,

Fig. 5 illustrates the forces acting on capelin, and

Fig. 6a and 6b shows a top and side view of a sorting device.

Fig. 1 shows one embodiment of the grading system 1 , where a stream of objects are delivered from an in-feed unit 2 to a size grader such as described in US-patent No.6,065,607 as shown in Fig. 2. It will be assumed that the object is capelin of different size and sex. In the embodiment described here the size grading is the first step of the grading and the second step of the grading is to sort the object of same size according to their characteristic, i.e. whether the capelin is female capelin filled with eggs 9, 9', 9", 9"', male capelin 11 , 11', 11", 11'" and asexual capelin 10, 10', 10", 10'".

The main object of the present invention is to separate the capelin of same size into female capelin 9, asexual capelin 10 and male capelin 11. This is done by means of utilizing characteristics of the capelins, i.e. different softness and surface structure, where the female capelin is filled with eggs 41 is softer than the other two capelin and has the lowest coefficient of friction but wherein the male capelin has brushes 40 and the highest coefficient of friction. This characteristic is essential for separating the capelin.

Figure 1 shows four different size groups of capelin 3, 4, 4b, 5 (the number of size groups may of course be more or less than four) wherein each size group comprises said female, male and asexual capelin. Using said size grader the smallest group of capelin is the one that is first to slide through said size grading means and follow the first path indicated by the arrow 6 to the separating unit 7, the second smallest slides through the size grader at some later time following the path 6' to a second separating unit 7' etc. Each size group hits a separating unit or units, which are mounted together and form separating unit belt, which moves with a constant speed. Figure 1 shows fours single separating units 7, 7', 7", 7'" from said belt. Each separating unit comprises pairs of inclined opposite arranged plates so that the top end opening of said units is larger than the bottom end opening. As each size group falls onto said units their original path is changed, depending on whether the capelin is female filled with eggs 9, 9', 9", 9'", male capelin 11 , 11', 11", 11'" and asexual capelin 10, 10', 10", 10'". While the dividing unit is moving with constant speed, the friction force is between the dividing units and the capelin is different, which results in said paths. It follows that the female capelin 9 slides approximately vertically through said separating unit 9, 9', 9", 9'" without changing it original path 8, the asexual and the male capelin are directed to paths 10, 10', 10", 10'" and 11 , 11', 11", 11'", respectively. A plurality of receiving bins 15, 15', 15", 15"', each being divided into sub-bins 12-12"', 13-13'" and 14-14'", receive said female, asexual and the male capelin. Accordingly, bin 15 comprises capelin of the smallest size, which has been sorted into female, asexual and the male capelin, bin 15' comprises the second smallest capelin etc.

Figure 2 shows one example of size grader . As the objects are delivered from the in- feed unit, it falls into slot 20, where the diameter of the slot increases with the distance from the in-feed unit 2 (not shown here). Accordingly, objects of the same size fall down when the diameter of the slots is larger than the width of the objects. Shown is also a plurality of separating units 7 arranged under the size grader.

Figure 3 shows a closer view of a single separating unit 7 and its moving direction indicated by the arrow 27. In this preferred embodiment the unit comprises two inclined rectangular plates 44,45 mounted to a conveying means (not shown) and arranged so that the top end opening (surface area of the opening) of the separating unit 42 is larger than the bottom end opening 43. These plates could also be bend or arranged in a different manner than indicated in this figure. Shown are the three types of capelin, i.e. the female capelin 9 filled with eggs 41 , the asexual capelin 10 and the male capelin 11 with a plurality of brushes 40.

Where the plates are moving with a constant speed during the grading process, they interact with the capelin with a friction force as the capelin touches the plates, wherein the friction force is parallel to the moving direction 27. This friction force, which will be discussed in more details in Fig. 5, is the cause of the change in paths of , the asexual capelin 8b and the male capelin 8c, whereas the female capelin 8a falls approximately vertical through the separating unit.

Figure 4 shows a plurality of separating units 17 arranged together so that they form a separating unit belt which has a moving direction indicated by the arrow 27 and is driven for example by a driving sprocket 28 wheel.

Shown is a stream of capelin with a similar size, which enters the separating unit at one position after being size graded. As the capelin falls on one of the two plates a friction force between the capelin and the plates causes a change in path 9, 10, 11 , depending on whether the capelin is a female capelin filled with eggs, asexual capelin or male capelin. In the embodiment shown in Fig. 4a, the sub-bins 12-14 are positioned directly under the separating units as shown.

Figure 5 illustrates the forces acting on the capelin. The female capelin filled with eggs 9, is the softest of the three products due to the "bag" 41 that carries the eggs. This is reflected in a very low (as shown, we assume

friction force. Therefore the total force acting on the female capelin consists approximately of the gravitational force F_g 30. The result is a vertical path 8a. For the asexual capelin 10 the plates 44,45, that form the separating unit 17, act with a friction friction force 35 on it. The total force F_totaι 31 is therefore the sum of the gravitational force F_g 30 and the friction force F_f1 from which path 8b follows. The angle α determines the curvature of the path 8b at the instant when the capelin leaves the separating unit and is determined from =tan^"1(F_g/F_f1). The male capelin is the product where the friction force is largest, resulting in angle β>α, with the largest path curvature 8c. This is mainly due to the brushes 40 that increase the friction force.

Figures 6a and 6b show another preferred embodiment of a grading device mounted to a supporting frame 56, where Figs. 5a and 5b show a top and side view. Preferably, the received objects have already been graded after their size at the in-feed station. However, for products such as capelin the size sorting is very seldom perfect. Therefore, an additional size separating unit is provided in this embodiment. As the objects fall from the feeding unit 57 they are separated into female capelin filled with eggs and male capelin into collecting bins 53 and 54. As described earlier, the separating unit reacts on the capelin with a friction force depending on weather it is female or male capelin and can therefore be collected into separated bags as described in Figs. 1-4.

Claims

1. A method for grading objects according to at least one characteristic property, said method comprising:

wherein objects flowing through the outlet of said separating follow at least one second path that is characteristic for at least one characteristic property of said objects, wherein objects following each path are collected together.

2. A method according to claim 1, wherein the object is capelin consisting of a female capelin filled with eggs, asexual capelin and male capelin.

3. A method according to claim 1 or 2, wherein the at least one characteristic property is a different stiffness of said objects.

4. A method according to any of the preceding claims, wherein the at least one characteristic property is a different surface roughness of said objects.

5 .A method according to any of the preceding claims, further comprising means for separating the products after their size prior to feeding them to the at least one separating unit.

6. A device for grading objects after at least one characteristic property comprising:

• means for transferring objects with at least one characteristic property, • at least one separating unit moving with constant velocity with an upward facing inlet for receiving said objects and an outward facing outlet for returning said objects, wherein said at least one separating units reacts on the objects with a friction force of different size depending on said at least one characteristic property,

• conveying means for conveying said at least one separating unit, and