WO1988006495A1

WO1988006495A1 - Grading apparatus for shrimps or other products consisting of discrete objects

Info

Publication number: WO1988006495A1
Application number: PCT/DK1988/000041
Authority: WO
Inventors: Ole Nielsen-Jexen; Knud Lenter; Poul Alex Rasmussen
Original assignee: Seamac Handels- Og Ingeniørselskab A/S
Priority date: 1987-03-06
Filing date: 1988-03-07
Publication date: 1988-09-07
Also published as: DK119787A; AU1425088A; DK119787D0

Abstract

The apparatus comprises a set of conveyor belts (7, 8) which are guided by guide rails in pairs of diverging paths between a run-on roller (4) and a run-off roller (5). The product to be graded is supplied piece by piece to the upper side of the belts and drop through the spaces between the belts of each pair, as these are gradually removed more and more from one another. Thereby a gentle grading is obtained. The belts (7, 8) preferably have a substantially circular cross-section.

Description

GRADING APPARATUS FOR SHRIMPS OR OTHER PRODUCTS CONSISTING OF DISCRETE OBJECTS.

The invention relates to a grading apparatus for shrimps or other products consisting of discrete objects. Since the grading of shrimps (frozen, shell-on fresh or peeled) is considered a particu¬ larly important field of use of the apparatus, this will in the following be described as applied to that purpose. The apparatus may, however, also be used for the grading of other products consisting of discrete objects, where similar grading problems are encountered. As examples of seafood products, that may conveniently be graded by means of the apparatus according to the invention, reference is made to mussels and Norway pout. Also live products, such as eel, salmon or other young fish can be graded by means of the apparatus according to the invention.

It is the object of the invention to devise a grading apparatus, by means of which the product to be graded is treated as gently as possible and, particularly, is not subjected to vigorous vibration, such as is the case with previously known grading apparatus.

To achieve this object, the invention is characterized in that the grading apparatus comprises a set of conveyor belts which are supported on guide rails and are guided by these in pairs of diverging paths from a run-on roller unit to a run-off roller unit, means for supplying the product from above to the spaces between the two belts of each pair, and means provided below the guiding rails for collecting the objects dropping through the spaces between the belts of each pair in different longitudinal regions of the paths of the belts from the run-on roller unit to the run-off roller unit.

In the use of this apparatus, the grading takes place during a smoothly progressing transport movement of the product so that this is practically not subjected to mechanical forces, and the risk of mutual damaging of the individual objects during the grading is reduced to a minimum.

With particular advantage, the belts may have a substantially circul r cross section. Hereby the advantage is obtained that the pieces of the product are tangentially supported on mutually facing curved surfaces and therefore automatically slide down these curved surfaces until they eventually drop through when the distance between the curved surfaces becomes too great.

Moreover, by using belts having a substantially circular cross section it becomes possible to obtain a particularly accurate guiding of the belts by adopting the features recited in claim 3.

Further features of the invention will be apparent to a man skilled in the art from the following detailed description of various preferred embodiments with reference to the drawing, in which

Fig. 1 shows an embodiment of an apparatus according to the inven¬ tion for the grading of shrimps, as seen from above, and with certain parts removed in the lower half of the figure,

Fig. 2 is a side view of the apparatus of Fig. 1,

Fig. 3 i an end view of the apparatus of Fig. 1,

Fig. 4 is a section on a larger scale along the line IV-IV in Fig. 2,

Fig. 5 is a section on the same scale along the line V-V in Fig. 2,

Fig. 6 is a section on a still larger scale through a guide rail and a belt supported therein,

Fig. 7 is a section on a still larger scale through a transverse bridge with supporting and adjustment means for the guide rails of the apparatus, the section being taken along the line VII-VII in Figs. 2 and 8,

Fig. 8 is a section through the same along the line VIII-VIII in Fig. 7,

Fig. 9 is an end view of the same, i.e. a view in the transverse direction of the apparatus,

Fig. 10 is a cross section through a further embodiment of a guide rail according to the invention,

Fig. 11 is a side view, corresponding to Fig. 2, of an apparatus, in which the guide rails are constructed as shown in Fig. 10, and

Fig. 12 is a cross section through a still further embodiment of a guide rail according to the invention.

The apparatus illustrated in Figs. 1-9 has a frame 1 which at its top comprises a longitudinal beam 2 at each side.

Four transversely extending belt rollers are rotatably mounted in the frame 1, viz. a driving roller 3, a run-on roller 4, a run-off roller 5 and a return run roller 6. A set of conveyor belts comprising pairs of belts 7,8 are passed around the rollers. Over the length from shortly after the run-on roller 4 to shortly before the run-off roller 5 each pair of belts 7,8 is slidably supported in a pair of guide rails 9,10 and are guided by these in diverging paths, so that the space between the two belts 7 and 8 of each pair is gradually increased in a direction from the run-on roller 4 to the run-off roller 5.

A feeding chute 11 is mounted on the frame adjacent the run-on roller end thereof. The chute 11 consists of a sheet material which is bent in such a manner as to form a number of grooves 12 of triangular cross section. Each of these grooves 12 is terminated at its forward end by lips 13,14 forming a narrowed outlet 15 immedia¬ tely above the space between a pair of belts 7,8.

A wide flow of shrimps is supplied to the feeding chute 11 in one layer from a feeding conveyor 16 at a rate so adjusted to the speed of travel of the belts that the shrimps, when dropping out through the outlets 15, will place themselves one by one on the space between the belts of each pair 7,8.

The feeding conveyor 16 may, e.g. be a vibrating conveyor, and the feeding chute 11, too, may be subjected to vibration in order to promote a uniform dropping-out through the outlets 15.

During the transportation on the belts, each shrimp will drop down through the space between the pair of belts on which it has placed itself, in the position where the width of the space between the belts 7 and 8 becomes too great to keep the shrimp supported. During the travel of the belts from the roll-on region to the roll-off region a drop-through of shrimps of increasing size will therefore take place.

Under successive longitudinal regions of the paths of the belts, collecting containers 101,102,103,104 are provided for collecting the dropping-through shrimps, and these are thereby graded according to size. In the region after the run-off roller 5 a further collecting container 105 can be provided for collecting the biggest shrimps that have not been able to drop down between the belts at the maximum distance between these. Instead of the collecting containers 101-105 other collecting means may be used, such as belt conveyors carrying the shrimps to the next processing station.

By increasing the number of drop-through and collecting regions, the number of grading ranges may be increased.

Under the belts chutes 17 are provided for ensuring a distinct separation between the regions, from which drop-down to the diffe¬ rent collecting containers takes place. Under the starting point of the first drop-down region a further chute 17 is provided for diverting dust and litter dropping through in the starting region of the paths of the belts.

In order to obtain a reliable grading it is important that the belts 7,8 of each pair should be guided in accurate diverging paths from the run-on roller to the run-off roller. This is the reason why the belts 7,8 are supported in and guided by guide rails 9,10, as previously mentioned. One form of a guide rail 9 is shown on a larger scale in Fig. 6. The rail has at its top a horizontal flange 18 for attachment to a number of transverse bridges, to be described in detail hereinafter with reference to Figs. 7-9. Then follows a body portion 19 which is slightly inclined inwards, i.e. towards the other rail 10 of the same pair, and below this an outwardly offset channel 20, which is downwardly delimited by a wall 21 having an upwardly inclined marginal portion 22.

This guide rail is suitable for guiding a belt 7 of circular cross- section. The mutual adaptation of the guide rail and the belt is such that the belt, when applying itself against the inclined marginal portion 22, will under the influence of its gravity slide down said portion, until it contacts the vertically extending bottom of the channel 20 and thereby arrives in an accurately defined position. The dimensioning should be such that both the body portion 19 and the edge of the inclined marginal portion 22 are withdrawn relatively to the innermost surface portion of the belt, so that the two guide rails 9 and 10 guiding a pair of belts will not interfere with the conveying and grading functions of the pair of belts. Moreover, the distance between the body portions 19 of the two guide rails 9 and 10 of a pair should, already in the region under the outlets 15 of the feeding chute 11, be sufficiently great to permit the shrimps to drop down on the belts 7,8.

As examples of suitable materials it should be mentioned that the guide rails may consist of stainless steel, while the belts may be polyurethane round belts, preferably with a rugged surface. By using these materials the friction between the belts and the guide rails will be low, and on the other hand the friction between the belts and e.g. shrimps lying thereon will be satisfactorily high.

The transverse bridge shown in Figs. 7-9 comprises two transverse supporting bars 23,24 and 25,26, respectively, which are formed as angle bars, each having a horizontal flange 23 and 25, respectively, supported on the longitudinal beams 2, and a vertical upright flange 24 and 26, respectively, the two flanges 24 and 26 facing inwardly towards one another.

A sleeve 27 having a vertical axis and provided with a transverse bore 28 is fastened to the upper side of the left-hand longitudinal beam 2. A spindle 29 extends through the bore 28 and is provided with two cylindrical flanges 30, by means of which it is rotatably mounted in the bore 28, and two protruding pins 31 and 32 with right-hand and left-hand screw thread, respectively. Two transversely extending sleeves 33 and 34, respectively, have transverse bores with corresponding threads for engagement with those of the pins 31 and 32, respectively. The sleeves 33 and 34 also have longitudinal threaded bores for receiving bolts 37 and 38, respectively, by means of which the vertical flange 24 and 26 of one and the other of the supporting bars are connected with the sleeve 33 and the sleeve 34, respectively. A handwheel 139 is fastened to the end of the pin 31. When this handwheel is turned, the two supporting bars 23,24 and 25,26 will be displaced in opposite directions.

All the left-hand guiding rails 9 are fastened to the under side of the supporting bar 25,26 by means of bolts 39, while all the right- hand guide rails 10 are fastened to the under side of the supporting bars 23,24 by means of bolts 40. Thus, by turning the handwheel 139 in one or the other direction the guide rails 9 and 10 of all pairs are simultaneously moved towards and away from one another, respec- tively.

The sleeve 27 is provided at its top with a threaded hole 41 for receiving a bolt 42, by means of which a bridge member 43, which extends across the vertical flanges 24 and 26 of the supporting bars and is provided with cheek plates 44 extending downwards along said flanges to tread on the horizontal flanges 23 and 25, respectively, of the supporting bars, can be urged inwards towards the sleeve 27 until the horizontal flanges 23 and 25, respectively, of the supporting bars are clamped against the beam 2 and are thereby locked relatively to the latter.

On the right-hand side beam 2 there is mounted a sleeve 27a of the same outer configuration as the sleeve 27, but without a transverse bore. The spindle 29 with the threaded pins 31 and 32 and the sleeves 34 and 35 are omitted. The bridge member 43 with the cheek plates 44 are maintained, so that the supporting bars can be locked against the side beam 2 at this end, too. When the bolts 42 are loosened, the supporting bars can slide forth and back between the cheek plates 44 and the sleeve 47a when displacement of the supporting bars and thereby the guide rails is effected at the left-hand side of the apparatus by means of the handwheel 139.

When the apparatus is started up with a new product, one may loosen the bolts 42 at both ends of each transverse bridge and adjust the handwheels 139 until the desired grading is obtained. Thereafter the bolts 42 are again tightened, so that the adjusted space between the guide rails of each pair will remain unaffected during operation. Similarly, an after-adjustment can be performed, whenever found necessary.

In the embodiment illustrated, transverse bridges of the kind illustrated in Figs. 7-9 are arranged in three positions A, B and C, cf. Figs. 1 and 2. Position C is located immediately ahead of the run-off roller 5, position A at a somewhat greater distance from the run-on roller 4, and position B intermediately between the positions A and C. The number and location of transverse bridges can be selected in accordance with the size and field of use of the apparatus. However, it will normally be recommendable to arrange one of the transverse bridges in position C in order to secure a correct guidance of the pair of belts 7,8 right up to the point where the belts are to pass over to the run-off roller 5.

Fig. 5 shows a construction of the run-off roller suitable to take over pairs of belts 7,8 from pairs of guide rails 9,10, for which the space between the guide rails 9 and 10 is differently adjusted. For each pair of belts, the run-off roller has a belt track 45, the width of which is adapted for accomodating a pair of belts when these are at their maximum distance from one another, for which the apparatus is designed to operate. The belt track 45 has a double- conical bottom with the maximum diameter in the middle where an obtuse ridge 46 is thus formed. If the guide rails 9,10 are adjusted at a smaller belt distance, the belts 7,8 will pull inwards towards the middle of the belt track 45, but owing to the double-conical shape of the bottom of the track 45 the belts will still be kept taut so that there is no risk that they will cross over one another across the ridge 46. In this manner it becomes unnecessary to use a run-off roller unit with mutually adjustable belt tracks for the two belts 7,8 of each pair, which would be a complicated and expensive contrivance both in manufacture and in use. The solution of the run-off problem illustrated in Fig. 5 operates at its optimum with belts of circular cross-section, which, as previously pointed out, are also particularly advantageous in respect of accurate guidance of the belts in the guide rails.

At the run-on roller 4 a similar problem usually does not exist because the pairs of guide rails 9,10, and thereby the pairs of belts 7,8, are here at their mimimum mutual distance which, in absolute measure, will not vary much from instance to instance. It is therefore possible to let the two belts 7,8 of a pair run in separate belt tracks 47,48 of conventional configuration. If neces¬ sary, a smooth rod or roller may be arranged above the paths of the belts in the region between the run-on roller 4 and the inlet ends of the guide rails 9,10 to ensure that the belts run correctly into the guide rails 9,10.

The guide rail 210 shown in Fig. 10, which is the right-hand rail of a pair of rails, differs from that shown in Fig. 6 In that, below the portions shown in Fig. 6 - for which the same reference charac¬ ters are used in Fig. 10 as in Fig. 6, with the addition of 200 - it comprises a downwardly extending additional body portion 249, at the lower longitudinal edge of which a guiding channel 250 is provided on the outer side of the body portion - i.e. the side facing away from the other guide rail of the same pair - the guide channel 250 serving to receive the return run of the same belt 208 as that the forward run of which is guided in the guiding channel 220.

An apparatus in which the guide rail of Fig. 10 is employed, is shown in Fig. 11. The overall construction of the apparatus is the same as in the embodiment first described, and in Fig. 11 the same reference characters are used as in Fig. 2 with the addition of 200. The main difference is that the rollers 3 and 6 have been omitted so that the belts 207,208 run directly from the run-off roller 205 through the guiding channels 250 of the guide rails 209,210 back to the run-on roller 204. Hereby a more steady running of the belts is obtained with less risk of spontaneous variations of tension, whereby also the guiding of the belts in the forward run guiding channels 220 - on which the accuracy of grading depends - is improved. Besides the building height is reduced. The run-on roller 204 may suitably be driven by an electric or hydraulic motor. Chutes 217 for delimiting the grading zones are arranged below the guide rails in similar manner as in Fig. 2. Transverse bridges of the kind shown in Figs. 7-9 are provided in four positions A, B, C and D. In these positions reinforcement bars 251 are also provided. These are attached to the outer side of the rails 209,210, at the top by clamping a bent-off portion 252 to the bridge together with the flange 218, in the zone of grinding channel 220 by attachment to a bracket 253, and further down by attachment to a bracket 254. The reinforcement bars serve to reinforce the relatively high rail profile, which may accordingly be constructed with a correspondingly smaller thickness.

In the embodiment illustrated in Figs. 10 and 11, the product to be graded drops from the feeding chute 211 down between the upper body portions 219 of the guide rails 209,210 down on the belts 207,208, and the graded product drops from the belts down between the lower body portons 249.

The guide rail 310 shown in Fig. 12 consists of a body portion 319, which at its top is provided on its outer side with a guiding channel 350 - corresponding to the guiding channel 250 in Fig. 10 - for the belt 308 considered, and at its bottom is provided on its inner side with a guiding channel 320 constructed in the same way as the guiding channel 20 in Fig. 6 and 220 in Fig. 10, the portions of the guiding channel 320 being denoted by corresponding reference characters in the 300-range.

By the construction shown in Fig. 12 a lower rail height is obtained than in Fig. 10, and thereby also a more rigid profile, which as a rule will not require reinforcement bars. Besides a still lower building height is obtained, in combination with an equally steady running of the belts.

The overall construction of an apparatus in which the guide rail shown in Fig. 12 is employed, may be substantially the same as that shown in Fig. 11, however with the modification that the direction of rotation is reversed, so that the forward run of the belts is below, and the return run above.

In the embodiments illustrated, the paths of the belts run horizon¬ tally between the run-on roller and the run-off roller. However, it is perfectly possible to arrange the paths of the belts at an upward inclination so that the apparatus besides a grading function also has an elevating function, if this is found to be convenient for fitting the apparatus into a production line.

It will be seen that the invention provides an apparatus that works not only gently, but also fast and rationally and consumes little space in relation to the quantity of a product that may be graded per time unit.

Owing to.the gentleness of the handling to which the product is subjected, the apparatus will also be suitable for the grading of young fish in fish farms. In this trade it is desirable to separate the bigger fish from the smaller ones in order to prevent the bigger fish from attacking and damaging the smaller ones, whereby the marketing value of the final product is reduced.lt is important that the fish should not suffer a chock in the grading operation since the growth may then be stopped for a longer period. It has been found that chock in the grading operation can be avoided by using an apparatus according to the invention, the shape of the guide rails being suitably selected in accordance with the size, shape and behaviour of the respective species of fish. The supply to the grading apparatus can take place with or against a flow of water.

Claims

P A T E N T C L A I S:

1. A grading apparatus for shrimps or other products consisting of discrete objects, c h a r a c t e r i z e d in that it comprises a set of conveyor belts (7,8) which are supported on guide rails (9,10) and are guided by these in pairs of diverging paths from a run-on roller unit (4) to a run-off roller unit (5), means (11,16) for supplying the product from above to the spaces between the two belts (7,8) of each pair, and means (101-105) provided below the guiding rails for collecting the objects dropping through the spaces between the belts (7,8) of each pair in different longitudinal regions of the paths of the belts from the run-on roller unit (4) to the run-off roller unit (5).

2. A grading apparatus as in claim 1, c h a r a c t e r i z e d in that the belts (7,8) have a substantially circular cross-section.

3. A grading apparatus as in claim 2, c h a r a c t e r i z e d in that the guide rails (9,10) are so shaped that the outer side of each belt (7,8) is caused by the gravity of the belt to apply itself against a lateral guiding face (20) of the respective guide rail (9,10).

4. A grading apparatus as in claim 1, c h a r a c t e r i z e d by adjustment means (27-39) by which the distance between the two guide rails (9,10) belonging to each pair of belts (7,8) can be adjusted simultaneously for all pairs of belts in suitably selected points (A,B,C) of the length of the guide rails.

5. A grading apparatus as in claim 4, c h a r a c t e r i z e d in that the run-off roller unit (5) comprises a roller which for each pair of belts (7,8) has a belt track (45), the width of which is adapted for accomodating both belts (7,8) when these are at their maximum distance from one another, for which the apparatus is constructed, and the bottom of which has a double conical shape with the largest diameter in the middle.

6. A grading apparatus as in claim 1, c h a r a c t e r i z e d in that the guide rails are provided on their outer sides with guiding surfaces for slidably supporting the return runs of the conveyor belts.

7. A grading apparatus as in claim 6, c h a r a c t e r i z e d in that the guide rails are so shaped that the return runs of the conveyor belts are situated at a higher level than their forward runs.