Self-cleaning infeed system for a machine for visual inspection

Abstract

 The invention relates to a self-cleaning infeed system for a machine for visual inspection, and to a machine for visual inspection of discrete bulkproducts, such as beans, peas, shrimps, nuts, raisins and similar, comprising such a self-cleaning infeed system. The self-cleaning infeed system according to the present invention causes a stable feeding in one layer of the discrete bulkproducts to be sorted.
The infeed system of the present invention is cleaned during service.

Description

Technical field of the invention

[0001] The invention relates to a self-cleaning infeed system for a machine for visual inspection of discrete bulkproducts, and to a machine for visual inspection of discrete bulkproducts comprising such a self-cleaning infeed system. The infeed system of the present invention is cleaned during operation.

Description of the prior art

[0002] Machines for visual inspection of discrete bulkproducts are known in the art. In the light of the present invention is understood under discrete bulkproduct any product consisting of individually distinct items, which all together are known in the art of visual inspection as bulkproducts, in that they are offered to the machine for visual inspection in bulk (the machine for visual inspection does not know when and where the distinct items will be present), and not as separate units. Examples of said discrete bulkproducts are beans, peas, shrimps, nuts, raisins and similar. Apples for example are considered in the art of visual inspection as being real discrete bulkproducts.

[0003] The known machines for visual inspection comprise an infeed system for feeding discrete bulkproducts to be inspected to an inspection unit. Said infeed system consists of a chute. A chute is a downward sloping plate, on which plate the discrete bulkproducts are directed to the inspection unit. When the discrete bulkproducts have just left the chute and are in free fall, they are inspected by the inspection unit, most commonly by means of electromagnetic radiation, and a decision is taken as to whether each of the discrete bulkproducts is acceptable or must be rejected. Products which are not acceptable, either contaminants or low-quality products, are rejected by means of a rejection unit, for example a compressed air device, and thus form a rejected stream of products.

[0004] Both the inspection unit and the rejection unit are known in the art and do not form part of the present invention.

[0005] In order to be able to carry out a good inspection and to take reliable decisions regarding the acceptability of the products, said products must be fed to the inspection unit in one layer, which must be stable. This obtaining of a single, stable layer is a known problem in the art of visual inspection.

[0006] In order to make the continuous stream of products more regular, an infeed system with a convex surface is proposed in WO 98/31477. The surface has a curvature in the direction of fall of the products concerned, and the curvature is equal to or slightly smaller than that of the path which the products should follow in free fall, independently of said surface.

[0007] All known machines for visual inspection of discrete bulkproducts, provided either with a straight or a curved chute, present the drawback that the discrete bulkproducts, and certainly shrimps, stick to the chute. The longer the visual inspection process continues, the more parts of the products to be inspected stick to the chute. After a while, newly arrived products to be inspected stick to these parts or bounce over these parts which stick to the chute. This causes the product stream to be inspected not to be stable.

[0008] Furthermore, once a large amount of discrete bulkproducts stick to the chute, they tend to slide down along the chute all together and go past the inspection unit in one stream of sludge, which makes the inspection unit and/or the detection unit to fail working correctly.

[0009] In order to restore the good operation of the apparatus for continuing the visual inspection process, the machine should be stopped, preferably before the stream of sludge comes down, and the chute should be cleaned. Of course this implies loss of time and thus is economically not desired.

Summary of the invention

[0010] It is an object of the present invention to provide an infeed system for a vision machine, such that a stable stream of products is delivered at the end of the infeed system.

[0011] It is another object of the present invention to provide a machine for visual inspection in free fall of discrete bulkproducts which makes it possible to present the discrete bulkproducts to the inspection unit in one layer which is stable, even if the products to be sorted tend to stick to the infeed system.

[0012] Therefore, a self-cleaning infeed system for a machine for visual inspection is provided. The self-cleaning infeed system comprises a conveyor having an endless conveyor surface and a cleaning means which is suitable for removing from the endless conveyor surface transported products which stick to said endless conveyor surface.

[0013] The cleaning means preferably consists of a scraper. A scraper is an edged instrument which is used to make a surface smooth or clean, by striking the instrument over the surface.

[0014] The scraper can be made for example of polyethyleen or any other synthetic material, but it can as well be made of metal.

[0015] The cleaning means can also be for example a flexible mat of silicon or of any other material.

[0016] The cleaning means preferably is positioned in sliding contact with the endless conveyor surface, preferably over its total width.

[0017] The cleaning means may be positioned substantially vertically or substantially horizontally, or it may be positioned such that it occupies any intermediate position in between said substantially horizontal and substantially vertical positions.

[0018] The present invention furthermore provides a machine for visual inspection in free fall of discrete bulkproducts to be sorted. Said machine comprises an infeed system, at least one inspection unit and at least one rejection unit. The infeed system is suitable to guiding discrete bulkproducts to be sorted to the inspection unit(s). The inspection unit(s) inspect(s) the products to be sorted, after which unacceptable products are rejected by the rejection unit(s). The infeed system is a self-cleaning infeed system according to the present invention, and comprises a conveyor having an endless conveyor surface and a cleaning means for cleaning the conveyor, more specifically for cleaning the endless conveyor surface. Said cleaning means removes particles which stick to the infeed system, and which would, if not removed, cause the discrete bulkproducts to be sorted to bounce over said sticking particles.

[0019] This self-cleaning infeed system causes a stable feeding in one layer of the discrete bulkproducts to be sorted.

[0020] The conveyer of the self-cleaning infeed system comprises driving means for moving the endless conveyor surface. Said driving means are suitable for moving the endless conveyor surface in the sense of movement of the discrete bulkproducts to be sorted, and/or for moving the endless conveyor surface in the opposite sense.

[0021] In a prefered embodiment the cleaning means is a scraper. Said scraper can be positioned substantially vertically or substantially horizontally, or can occupy any position in between said substantially vertical and substantially horizontal positions.

[0022] If the endless conveyor surface is driven by the driving means such that the endless conveyor surface moves in the opposite sense of the sense of movement of the discrete bulkproducts to be sorted, it is prefered to position the cleaning means substantially vertically at the bottom side of the conveyor, and preferably at a position such that parts scraped off the endless conveyor surface may be gathered easily with the stream of rejected products which is caused by the rejection unit.

Short description of the drawings

[0023] The invention will now be described in more detail by means of the embodiment represented in:

[0024] Fig. 1, showing a schematic perspective view of a machine for visual inspection provided with a self-cleaning infeed system according to the present invention.

Description of the preferred embodiment

[0025] A machine for visual inspection 1 provided with a self-cleaning infeed system 2 according to the present invention is represented in Fig.1. The self-cleaning infeed system 2 comprises a conveyor 3 having an endless conveyor surface 4. The conveyor 3 is driven by means known in the art, for example by drive rollers 5, 6.

[0026] Discrete bulkproducts to be sorted 7, such as for example beans, peas, shrimps, nuts, raisins and similar, are fed to the self-cleaning infeed system 2 of the machine for visual inspection 1, for example by means of a vibrating table 8. After having left the vibrating table 8, the discrete bulkproducts to be sorted 7 lie on the endless conveyor surface 4 of the self-cleaning infeed system 2, to which parts of the products tend to stick. The endless conveyor surface 4 of the conveyor 3 preferably moves in the sense opposite to the sense of movement of the discrete bulkproducts to be sorted 7, as represented by the arrow 9. The conveyor 3 moves rather slowly, for example 1 tour per 10 seconds.

[0027] At the lower end 10 of the conveyor 3, the discrete bulkproducts to be sorted 7 leave the conveyor 3 in free fall, due to the gravity, and form a stream of falling products to be sorted 14. Immediately thereafter, the falling products to be sorted 14 are inspected by means of an inspection unit 11 as known in the art. Such an inspection unit 11 for example comprises one (for single side inspection) or more (for dual side inspection) laser sources 12a, 13a and one or more inspection drums 12b, 13b. The laser sources 12a, 12b send some specific electromagnetic radiation (chosen in function of the products to be sorted) towards the falling products to be sorted 14, and rays reflected from the the product and the inspection drums 12b, 13b are used to decide whether any of the falling products to be sorted 14 is of lower quality and has to be rejected.

[0028] Likewise, the inspection unit 11 can comprise, instead of the laser sources 12a, 13a and the inspection drums 12b, 13b, an illumination unit and a camera (not represented), as known in the art. Then the illumination unit sends some electromagnetic radiation towards the falling products to be sorted 14, and the camera captures an image of said falling products to be sorted 14. On the basis of said image, a decision is taken as to whether any of the falling products to be sorted 14 is of lower quality and has to be rejected.

[0029] If a contaminant or a lower quality product is detected, a rejection unit 15, as known in the art, actuates a mechanism, often a compressed air device, to remove unacceptable products from the stream of falling products to be sorted 14. In that way two streams of discrete bulkproducts are created and separated from each other: a stream of accepted products 17 and a stream of rejected products 16.

[0030] A cleaning means 18 is provided to clean the endless conveyor surface 4 of the conveyor 3. Said cleaning means 18 may for example consist of a scraper placed at the bottom side 19 of the conveyor 3. Said scraper scrapes the endless conveyor surface 4 and in that way removes the discrete products to be sorted 7 which are sticked to the conveyor 3.

[0031] In the prefered embodiment as shown in Fig. 1, the scraper is put in a substantially vertical position and can be adjusted in that direction. Said adjustment can be carried out in order to put the scraper closer to or farther away from the endless conveyor surface 4. Other positionings of the scraper could as well be considered, such as a substantially horizontal position, or each intermediate position between the substantially horizontal and the substantially vertical positions.

[0032] The cleaning means 18 preferably presents a first and a second end, said first end being positioned towards the conveyor surface. The first end is edged, preferably over the total width of the conveyor 3. The forming of an edged end may for example be done by taking away one or more parts of a lath.

[0033] Some of the discrete bulkproducts to be sorted 7 will still tend to stick to the conveyor 3, but this does not harm the operation of the infeed system, as they are scraped off almost immediately (in any case within one tour of the conveyor 3). They do not stick somewhere in the middle of a chute where the mass of sticking products grows and cause other products to be sorted 7 to bounce downwardly; contrary to what is known in the art.

[0034] When the endless conveyor surface 4 moves in a sense opposite to the sense of movement of the discrete bulkproducts to be sorted 7, the parts of products which stick to the endless conveyor surface 4 and are scraped off by the cleaning means 18, form a stream of scratched off products 20 which may easily be gathered with the rejected products 16 which are removed from the falling products to be sorted 14 by the rejection unit 15.

Claims

1. Self-cleaning infeed system (2) for a machine for visual inspection, comprising a conveyor (3) having an endless conveyor surface (4), characterised in that it furthermore comprises a cleaning means (18) which is suitable for removing from the endless conveyor surface (4) transported products which stick to said endless conveyor surface (4).

2. Self-cleaning infeed system (2) according to claim 1, characterised in that the cleaning means (18) consists of a scraper.

3. Self-cleaning infeed system (2) according to claim 1, characterised in that the cleaning means (18) consists of a flexible silicon mat.

4. Self-cleaning infeed system (2) according to any of the preceding claims, characterised in that the cleaning means (18) is positioned in sliding contact with the endless conveyor surface (4).

5. Self-cleaning infeed system (2) according to any of the preceding claims, characterised in that the cleaning means (18) is positioned substantially vertically.

6. Self-cleaning infeed system (2) according to any of claims 1 to 4, characterised in that the cleaning means (18) is positioned substantially horizontally.

7. Self-cleaning infeed system (2) according to any of claims 1 to 4, characterised in that the cleaning means (18) occupies an intermediate position between a substantially vertical and a substantially horizontal position.

8. A machine for visual inspection (1) in free fall of discrete bulkproducts to be sorted (7) comprising an infeed system, at least one inspection unit (11) for inspecting the discrete bulkproducts to be sorted (7), and at least one rejection unit (15) for rejecting unacceptable products detected by the inspection unit (11), the infeed system suitable to guide discrete bulkproducts to be sorted (7) to the inspection unit (11), characterised in that the infeed system is a self-cleaning infeed system (2) according to any of the preceding claims.

9. A machine (1) according to claim 8, characterised in that the conveyor (3) is provided with driving means (5, 6) for moving the endless conveyor surface (4) in the sense of movement of the discrete bulkproducts to be sorted (7).

10. A machine (1) according to any of claims 8 or 9, characterised in that the conveyor (3) is provided with driving means (5, 6) for moving the endless conveyor surface (4) in a sense opposite to the sense of movement of the discrete bulkproducts to be sorted (7).

Drawing