Apparatus for forming a continuous layer of granular and/or pulverulent flowable material in a breadcrumb coating machine

Abstract: A method for forming a moving, continuous bed which is composed of granular and/or pulverulent flowable material and which is of constant thickness provides an improved uniformity of the bed by collecting material from a first moving bed so as to form a buffer stock, and by subsequently delivering material from the stock in a regular fashion so as to form a second moving bed which is continuous. An apparatus for carrying out this method comprises a belt capable of being passed through by said material. The material can be moved with the belt over a guide plate situated beneath the belt. In order to prevent too little material being present locally during brief interruptions in the supply of the flowable material and in order to prevent the material being compressed and pulverized in the event of an excessively large supply, a buffer is provided for the material, the discharge opening of which buffer is situated near and above the guide plate. The buffer has an overflow. The material is thus fed via the buffer onto the belt. Provided the buffer remains filled, it is capable of compensating automatically for fluctuations in the material supply.

Description: The present invention relates to a method for forming a continuous layer which is composed of granular and/or pulverulent flowable material and which is of constant thickness, which apparatus has at least one belt Such apparatus is known from US-A-4516524. In said known apparatus, two separate belts are applied for feeding respectively discharging the granular material. Such an arrangement with two separate belts is not desirable, having regard to the additional mechanical components and drives which lead to a rather complex construction. The aim of the invention is to provide such apparatus which is simpler, and therefore less vulnerable with respect to malfunctions. This aim is achieved by the features of the characterizing portion of claim 1. According to a first possible embodiment, the buffer is situated near the end edge, which end edge is foremost in the direction of movement of the uppermost run, of the guide plate beneath said run, in such a way that the material from the uppermost run can be fed into the buffer. According to a second possible embodiment, the buffer is situated near the end edge, which end edge is foremost in the direction of movement of the uppermost belt section, of the guide plate beneath the uppermost belt section, in such a way that the material from the uppermost section can be fed into the buffer. The apparatus according to the invention is in particular suitable for handling sensitive material. The fact is that such material may, readily be pulverized during transportation, as a result of which the content of fine, pulverulent material increases at the expense of the content of coarser, granular material. This is very undesirable since the coarse and fine component demix, in which process the coarse component ends up on top and the fine component sinks downwards. In this case, the risk is great that the apparatus no longer delivers a constant mixture over the layer but a lower layer composed of a relatively large amount of fine material and an upper layer containing a relatively large amount of coarse material. In that case, end products having a constant quality can no longer be delivered. In contrast thereto, the apparatus according to the invention has a favourable effect on the maintenance of the desired mixture distribution of coarse- and fine-grained material. Owing to the speed with which the belt, and therefore the material, advances, the coarse-grained constituents thereof are propelled somewhat further in the direction of movement of the belt than the fine-grained portions when they fall downwards from the guide plate. As a result of this, a relatively larger portion of the coarse-grained material is able to reach the buffer; the fine-grained material is propelled less far, with the result that a relatively larger portion of the fine-grained material is unable to reach the buffer, falls over the overflow and is removed. This last effect occurs especially if partial demixing has taken place, in which case, the lowermost portion of the layer is composed of a relatively large amount of fine-grained material. This falls away rapidly after leaving the guide plate without it being able to be entrained by the coarse-grained material. In this connection, the mixing ratio of the mixture conveyed round does not have to change in any way, for example by the coarser material nevertheless still being pulverised to some extent. In some mixtures it may be desirable that the mixture contains as little fine-grained material as possible; in that case, too, the apparatus according to the invention has a beneficial effect since any fine-grained material formed while the coarse-grained material is being conveyed round is automatically removed via the overflow. In this connection, the apparatus is preferably of a construction such that an overflow plate adjoins the rearmost edge of the buffer in a downwardly sloping direction and extends beyond or next to the second belt section in a manner such that the granular material fed by the first belt section first of all falls mainly into the buffer and, when the latter is full, overflows towards the overflow plate. With this construction it is possible to avoid the overflow material finishing up, if the feed of material is extremely great, on the already formed continuous layer. The excess material falls via the overflow plate through the penetrable belt without affecting the thickness of the layer. Preferably, the buffer comprises a hopper having an essentially vertical hopper plate and also a hopper plate which is situated behind it in the direction of movement of the uppermost belt section and extends downwards at an angle towards the essentially vertical hopper plate, which two hopper plates define a hopper gap extending over the width of the guide plates. If it is provided at the same time that there is present between the essentially vertical hopper plate and the guide plate situated beneath the central belt section a slot whose size essentially corresponds to the belt thickness and that a discharge gap for the material is situated between the sloping hopper plate and said guide plate, the desired dosaging of the material can be obtained by a suitable choice of the hopper gap and the discharge gap. To reduce the risk of the occurrence of blockages, the discharge gap may be chosen to be larger than the hopper gap. According to a preferred application of the invention, the apparatus is used in a machine for coating edible products with breadcrumbs. Such machines are also known from NL-A-7810080. In the latter, the outlet of the means for providing the uppermost layer of breadcrumb coating material is situated above the uppermost run of the belt. In the machine according to the invention the excess material originating from the uppermost run of the belt finishes up on the lowermost run, after which it is fed to the buffer. In this connection, the machine is preferably provided with an apparatus according to one of Claims 4 to 11 inclusively and the guide plate extends below the uppermost run of the belt in the direction of movement of said run from the deflector to a point above the guide plate beneath the uppermost section of the belt of the lowermost run. In this manner, the beneficial effects already mentioned relating to avoiding demixing and the formation of a layer having a uniform thickness, as already discussed, are influenced beneficially. If, at the same time, the machine is of a construction such that the guide plate beneath the uppermost belt section of the lowermost run extends downwards at an angle at its end facing the overflow plate and its front edge is situated at a distance, in the direction of movement of said belt section, from the rearmost edge of the hopper in a manner such that, if the material in the hopper has accumulated to a level higher than the rearmost edge, the material subsequently fed impinges on said material which has accumulated to a point above the rearmost edge of the hopper and overflows over the overflow plate, the excess overflowed material can immediately be conveyed round again. The outlet may also be provided with a sieve over which the breadcrumb coating grains can be moved in a direction opposite to the direction of movement of said uppermost run and whose sieve openings are larger than the size of the largest grains. The coarse-grained material slides further over the sieve than the fine-grained material. As a result, the products to be treated are first coated with a coarse-grained layer and it is only after that that the fine-grained material falls in between. All these features have a beneficial effect on the adhesion of the coarse-grained material and the outer appearance of the final product. The known machine has a feedstock container for the material with a transportation device situated therein for feeding the inlet of the means for providing the uppermost layer of material. According to the invention, a sensor linked to the transportation device may be situated near the outlet of said means, which sensor controls the transportation device as a function of the quantity of material discharged from the outlet. The invention will be explained in more detail below with reference to an exemplary embodiment shown in the Figures. Figure 1 shows a machine for coating edible products with breadcrumbs which is provided with an apparatus according to the invention. Figure 2 shows the apparatus according to the invention in accordance with detail II of Figure 1. The machine shown in Figure 1 for coating edible products with breadcrumbs has, in a known manner, an endless belt 1 which can be passed through by the granular and/or pulverulent breadcrumb coating material and which is conveyed round over two end rollers 2, 3. The direction of movement of the belt is indicated by arrows. The products 5 to be coated with breadcrumbs are fed by means of a separate conveyor 4 onto the uppermost run 6 of the belt. At the foremost end in the direction of movement of said uppermost run 6, the breadcrumb coated products are subsequently removed by means of an apparatus which is not shown. The machine is furthermore provided with a feedstock container 7 for the breadcrumb coating material, which feedstock container contains a screw jack 8 which feeds the breadcrumb coating material to the inlet 9 of a pumping apparatus 10. Said pumping apparatus 10 pumps the breadcrumb coating material to the outlet 11, where the breadcrumb coating material slides over the slide track 12 towards the sieve 13. During this process, the coarser grains of the breadcrumb coating material slide further across the sieve than the finer grains in a manner such that mainly coarse-grained material falls first of all onto the products to be coated with breadcrumbs and only after that the fine-grained material. As a result, the fine-grained material finishes up between the coarser grains on the product, as a result of which the desired outward appearance of the final product can be ensured. Situated beneath the uppermost run of the belt is the guide plate 14. The breadcrumb coating material fed via the sieve 13 moves with the belt 1 over the guide plate 14 until the front edge 15 of the guide plate 14 is reached. The breadcrumb coating material which has not yet adhered to the final products falls through the belt 1 after passing the front edge 15 onto the lowermost run 16 of the belt 1. In this connection, a blowing apparatus 39 may optionally be provided in order to accelerate the removal of the excess material. The lowermost run 16 of the belt 1 comprises three sections: an uppermost section 17, a central section 18 and a lowermost section 19. All these features are shown on a larger scale in Figure 2. Said three sections 17, 18 and 19 are obtained by guiding the lowermost run 16 round over the rollers 20 and 21. At the same time, a guide plate 22 is situated beneath the uppermost section 17, a short guide plate 23 beneath the central section 18 and a guide plate 24 beneath the lowermost section 19. Situated between the uppermost belt section 17 and the central belt section 18 is a hopper comprising an essentially vertical hopper plate 25 and a sloping hopper plate 26. Said hopper plates form a hopper gap extending transversely with respect to the belt 1; the hopper is closed at the sides by means of aprons which are not shown. The guide plate 23 is now situated beneath the hopper gap 27 at a distance from the vertical hopper plate 25 such that the central belt section 18 is able to move between these two, and, furthermore, at a distance from the sloping hopper plate 26 such that the material which has passed through the hopper gap 27 can be removed together with the central belt section through the discharge gap 28 formed between guide plate 23 and sloping hopper plate 26. After the material has been passed over the guide plate 23, it falls through the central belt section 18 onto the lowermost belt section 19, where it is conveyed together with said belt section 19 over the guide plate 24. The above described apparatus with hopper according to the invention functions as follows. An amount of material 29 having a certain layer thickness is fed with the uppermost belt section 17 over the guide plate 22. The thickness of said layer is generally not uniform since the material originates from the uppermost run 6 of the belt 1, where a portion of the material has already been used. The material slides via the sloping front edge 30 of the guide plate 22 towards the hopper formed by the plates 25, 26. Depending on the amount of material 29 fed, the hopper more or less fills up. In this connection, the position of the front edge of the sloping plate 30 with respect to the edge 31 of the hopper which is rearmost in the direction of movement of the uppermost belt section 17 is so chosen that the greatest portion of the material is propelled towards the hopper. Any fine material situated at the bottom of the layer 29 falls downwards relatively rapidly, with the result that a portion thereof finishes up in front of the rearmost edge 31 of the hopper and is removed via the overflow plate 32 adjoining the rearmost edge 31. As can be seen in Figure 1, said material removed via the overflow plate 32 finishes up at the inlet 9 of the pump 10, with the result that it can be conveyed round again. If more material is being fed into the hopper than is being removed via the hopper gap 27 and the discharge gap 28, an amount of material 33 will form in the hopper, which material will ultimately project above the rearmost edge 31 of the hopper. The consequence of this is that the material arriving via the front edge 30 of the guide plate 22 impinges on the slope formed by the material 34 and is also removed via said slope and the overflow plate 32 to the inlet 9 of the pump 10. Provided that the hopper formed by the plates 25, 26 is completely or partly full, a constant amount of material per unit time is removed with the central belt section 18 through the discharge gap 28, as a result of which a layer of material 35 having a constant thickness is formed on the lowermost belt section 19. The thickness of said layer 35 can be regulated by a suitable choice of the size of the openings 27, 28. Furthermore, the discharge gap 28 is preferably chosen larger than 27 in order to counteract the occurrence of blockages. As depicted in Figure 1, the material 35 on the lowermost run 19 is fed to the roller 2, where a deflector 36, which is known per se, is provided with which the material 35 can be conveyed around to the uppermost run 6. A layer of breadcrumb coating material having constant thickness 37 is consequently also formed on said run onto which the products 5 are fed. Further breadcrumb coating material is fed via the sieve 13 as already mentioned, as a result of which the products 5 are coated on the upper side. Finally, provided above the slide track 12 is a sensor 38 which detects the amount of breadcrumb coating material which slides over the slide track 12. Said sensor is coupled to the drive of the screw jack 8 in a manner such that, if too little material is flowing over the slide track 12, the screw jack 18 is set in operation. The breadcrumb coating material is then fed out of the feedstock container 7 to the inlet 9 of the pump 10. The required feed of breadcrumb coating material can consequently be ensured.

Claims: Apparatus for forming a continuous layer composed of granular and/or pulverulent flowable material and of constant thickness, which apparatus has at least one belt (1), characterized in that said belt (1) has an uppermost run (6) and a lowermost run (16), the lowermost run (17) of the belt (1) is twice oppositely guided downwards in the direction of movement so as to form three belt sections (17, 18, 19) extending essentially beneath one another, and in that there is located beneath the highest of said three belt sections a buffer fed by this belt section (17) and whose outlet is situated above a guide plate (24) situated beneath the lowest of said three belt sections (19), said belt (1) is capable of being passed through by said material, as well as of passing said material over guide plates (14, 22) situated beneath the uppermost run (6) and the highest of said three belt sections (17). Apparatus according to claim 1, characterized in that the buffer is situated near the end edge (30) of the guide plate (22) beneath this belt section (17), which end edge (30) is foremost in the direction of movement of the highest of said three belt sections (17), in such a way that the material from the uppermost section (17) can be fed into the buffer. Apparatus according to claim 2, characterized in that the buffer is situated between the uppermost (17) and central (18) belt sections. Apparatus according to Claim 3, characterized in that an overflow, plate (32) adjoins the rearmost edge (31) of the buffers in a downwardly sloping direction and extends beyond or next to the central belt section (18) in a manner such that the material fed by said highest belt section (17) first of all falls mainly into the buffer and, when the latter is full, overflows towards the overflow plate (32). Apparatus according to one of Claims 2 to 4 inclusively, characterized in that the buffer comprises an essentially vertical hopper plate (25) and also a hopper plate (26) which is behind it in the direction of movement of the uppermost belt section (17) and extends downwards at an angle towards the essentially vertical hopper plate (25), which two hopper plates (25, 26) define a hopper gap above of the lowermost guide plate (24). Apparatus according to Claim 5, characterized in that the overflow plate (32) and the sloping hopper plate (26) are composed of one piece of sheet material bent along a straight bending line, which bending line defines the rearmost edge (31) of the hopper. Apparatus according to Claim 5 or 6, characterized in that there is situated, under the central belt section (18) at the height of the hopper outlet (27), a guide plate (23) which leaves free a part thereof which is foremost in the direction of movement of said central belt section (18). Apparatus according to Claim 7, characterized in that there is present, between the essentially vertical hopper plate (25) and the guide plate (23) situated beneath the central belt section (18) a slot whose size essentially corresponds to the belt thickness, and in that a discharge gap (28) for the granular material is situated between the hopper plate (26) extending downwards at an angle and said guide plate (23). Apparatus according to Claim 8, characterized in that the discharge gap (28) is larger than the hopper gap (27). Apparatus according to one of Claims 2 to 9 inclusively, characterized in that the guide plate (22) situated under the highest of the three belt sections (17) is bent downwards at an angle in the direction of the rearmost edge (31) of the hopper. Machine for coating edible products with breadcrumbs, provided with an apparatus according to one of the preceding claims for forming a lowermost layer of breadcrumb coating material, means (4) for feeding the edible products (5) onto the lowermost layer of breadcrumb coating material and also means (8-13) for forming an uppermost layer of breadcrumb coating Machine according to Claim 11, in which the outlet of the means (4) for providing the uppermost layer of breadcrumb coating material is situated above the uppermost run (6) of the belt (1), characterized in that the machine, is provided with an apparatus according to one of Claims 3 to 7 inclusively and in that the guide plate (14) extends below the uppermost run (6) of the belt (1) in the direction of movement of said run (6) from the deflector (36) to a point above the guide plate (22) beneath the highest belt section (17) of the lowermost run (16). Machine according to Claim 12, characterized in that the guide plate (22) beneath the highest of the three belt sections (17) of the lowermost run (16) extends downwards at an angle at its end (30) facing the overflow plate (32) and its front edge is situated at a distance, in the direction of movement of said belt section (17), from the rearmost edge of the hopper in a manner such that, if the material in the hopper has accumulated to a level higher than the rearmost edge, the material subsequently fed impinges on said material which has accumulated to a point above the rearmost edge of the hopper and overflows over the overflow plate (32). Machine according to Claim 13, characterized in that the lower edge of the overflow plate (32) is situated above the inlet of the means (8-13) for providing the uppermost layer of material. Machine according to Claim 14, characterized in that the outlet is provided with a sieve (13) over which the material can be moved in a direction opposite to the direction of movement of said uppermost run (6) and the sieve openings are larger than the size of the largest grains of the material. Machine according to Claim 14 or 15, characterized in that, near the foremost end (15), in the direction of movement of the uppermost run (14) of the belt (1), of its guide plate (14), a blowing apparatus is situated for blowing away excess material towards the lowermost run (16) of the belt (1). Machine according to one of Claims 12 to 16 inclusively provided with a feedstock container (7) for granular material with a transportation device (8) situated therein for feeding the inlet of the means (9-13) for providing the uppermost layer of material, characterized in that a sensor (38) linked to the transportation device is situated near the outlet of said means, which sensor (38) controls the transportation device (8, 10) as a function of the quantity of material discharged from the outlet (11).

Inventors: KOPPENS WILHELMUS FRANCISCUS A, KOPPENS, WILHELMUS FRANCISCUS ANTONIUS
Applicants: KOPPENS MASCHF BV, KOPPENS MACHINEFABRIEK B.V.
Application year: 1990
Main classification: A23P1
IPC codes: A23G3, A23P1, A21C9