EP0022291B1 - Method and device for dosing filling material which hardly lends itself to filling - Google Patents

Abstract

1. Process for the dosing of products that are difficult to fill into packages, for example foodstuffs such as blanched spinach, endive, sliced green beans, vegetable mixes, noodle mixes etc., into portions of uniform weight, in which the products to be packaged from a storage container are formed into a compressed column, are pushed into a dosing chamber of a volumetric dosing device and are divided into separate portions, characterized in that the compression of the column is effected by compressing it several times transversely to its axis, the column during or at the end of the compression being conveyed positively downwards and the lateral pressure on the column being only removed after the latter step.

Description

The present invention relates to a method and an apparatus for dosing difficult-to-fill goods, e.g. Foodstuffs such as blanched spinach, endive, sliced green beans, vegetable mixes, pasta mixes, etc., in portions of the same weight, by shaping the contents from a storage container into a compacted column, pushing them into a metering chamber of a volumetric metering device and dividing them into individual portions. As a result of the irregular, fibrous, sheet-like or strand-like structure and the moisture that may be present on the surfaces, some foods tend to form an inhomogeneous mass with more or less large air pockets. However, these foods must also be carefully transported and dosed so that their structure is preserved, the moisture contained in them is not squeezed out or there is no segregation.

A device of the type described at the outset is known from DE-C-433 338 and consists of parallel strips which can be moved in and out of one another in groups. Tobacco is stowed between these groups of strips with a pusher and then pushed into a container by the groups of strips with constant pressure. The amount of tobacco then present in the container is cut off from the remaining tobacco rod with a knife.

If such a device is used for sensitive filling goods, such as vegetables, they will suffer considerable damage from the impact. In addition, due to the limited connection of these fillings, the pressure generated would partially flow back when the strip groups and the container were opened.

While free-falling products of the same shape and size can be metered volumetrically without difficulty and liquid products, even if they have a higher viscosity, can be metered by pumps, e.g. Spinach leaves are usually filled into the packaging by hand, whereby large weight variations are unavoidable. There are filling and dosing devices working with pistons, but large weight scatter and product damage are also inevitable.

The present invention is therefore intended to gently compact the difficult-to-fill foods into a mass from which portions of uniform weight, measured volumetrically, are divided in order to introduce them into packaging containers.

The method according to the preamble of claim 1 (DE-C-433 338) is characterized in that the compression of the column takes place in that it is gradually compressed several times across its axis, the column being positive during or at the end of the compression transported downwards into a dosing chamber and only then is the lateral pressure on the column released. Since the column is mechanically compressed to a limited extent only transversely to the transport device and, in addition, working like a piston in the transport direction, without being subjected to thrust, the food is not squeezed. Since the pressure on the column is essentially only exerted from the side, an equalization of the pressure in the axial direction and corresponding displacements of parts of the food are possible in the column, but without segregation taking place in the case of mixtures. Since the product can flow back upwards when the column is compressed, the upper part of the column acts on its lower, compressed end like an elastic piston and reproducible results are achieved.

The transport direction of the column is preferably perpendicular downwards, but transport in a direction obliquely downwards is possible. The device for carrying out the method is provided with a channel of variable cross-section arranged between a storage container and a metering device, which channel is arranged between two fixed plates which form opposite channel walls and two blocks or plates which form the two other channel walls and are axially and mutually movable , Which blocks or plates on their sides facing the channel are wavy or step-shaped profiled (DE-C-433 338), characterized in that the plates or blocks are wedge-shaped and movable on inclined sliding surfaces, so that a movement towards the dosing device adjoining the duct also results in a reduction in the duct cross-section, and that the duct is arranged downwards and preferably perpendicularly.

The blocks or plates are profiled on their sides facing the interior of the channel in the form of waves, steps, teeth or the like. The axial movement of the blocks in the direction of the metering device adjoining the channel also results in a reduction in cross-section, while an opposite axial movement increases the distance between the inner sides of the blocks and thus the channel cross-section. (The axial movement of the blocks is understood here as the proportion of the movement of the blocks in the direction of the axis of the channel).

The angle of inclination between each sliding surface and the central axis of the channel is preferably between 12 and 25 °. The wedge angle of the blocks between their side movable on the sliding surface and the line of contact with the wave-shaped or step-shaped profiles of their inner side is likewise approximately 12 to 25 °. The inner sides of the two blocks can face each other that be parallel. In this case, the two aforementioned angles are the same. Since the food in the upper part of the column is still very loose, it can also be expedient to choose a larger distance between the upper ends of the blocks than between the lower ends. The lines of contact with the wave-shaped or step-shaped profiles can also be curved.

In a preferred embodiment it is provided that the upper ends of the blocks are compressible at the beginning of their axial movement, which runs in the direction of the metering device, whereby they are lifted off the sliding surfaces. During the axial downward displacement, the lower ends of the blocks form the fulcrum on the inclined sliding surfaces. During the subsequent axial displacement of the blocks upwards to the starting position, the blocks lie on the sliding surfaces along their entire length.

The axial stroke of the blocks or the length of their downward movement is at least approximately equal to the depth of the metering chamber arranged under the channel. However, a larger maximum stroke of the blocks can be provided, and in the case of a device used, the maximum possible stroke in the case of a device used was, for example, 7 cm with a depth of the metering chamber of 5 cm. The height of the channel is at least five times the stroke. The cross section of the channel is not smaller in its upper part when the blocks are compressed than the cross section of the metering chamber. The cross section in the lower part of the channel can, however, be smaller than the cross section of the metering chamber when the blocks are compressed. The blocks hold the column in place while the filled dosing chamber is pushed aside and drop the column as soon as the empty dosing chamber is brought back under the channel, so that the dosing chamber is at least partially filled by the falling column.

The lower ends of the wedge-shaped blocks are roughly blunt in accordance with the wave-shaped profile, so that during a downward movement the blocks can push the parts of the food that are possibly below their lower ends against the sliding surfaces while simultaneously compressing in the axial direction and across the column into the metering chamber.

The drive of the wedge-shaped blocks or of plates which functionally correspond to them is preferably carried out by pneumatic, possibly also by hydraulic devices, in which a piston is moved back and forth in a cylinder. The movements of the piston of such a device are transmitted to the blocks by levers. The pressure exerted on the column can be influenced by regulating the medium driving the pistons. The movement of the blocks compressing the column can be limited in that the pressure arising in the column, or the pressure acting on the pneumatic device from the column via lever ratios, becomes equal to or greater than the pressure of the drive medium. In this case, the movement of both the blocks and the pistons is braked, and the blocks only make part of their maximum possible movement stroke. This also contributes to a gentle treatment of the food in the column during the compression. In addition, by regulating the pressure of the drive medium, the degree of compression and thus, within narrow limits, the weight of the contents accommodated in the metering chamber can also be controlled. The pressure of the drive medium must never be so great that the food is crushed and its cell structure is damaged.

In the case of foods which contain a relatively large amount of free water, such as can occur undesirably with spinach leaves, it is possible to push the water out of the column, in particular upwards, by increasing the pressure of the drive medium. In this case, openings must be provided on the channel through which the excess water can drain off, and the weight of the portions must be precisely adjusted by changing the contents of the dosing chamber.

For frozen, free-flowing food mixes that consist of particles of very different shapes and sizes, the pressure must be set so that the particles do not freeze together to form a solid column. Here, the channel cross-section between the blocks is always completely filled with the particles, whereby the compression increases downwards. The device is particularly advantageous for dosing frozen particles because the transport time from a store to the individual packaging is very short and because there is no change in the mixing ratios during this transport.

A rotary slide valve is preferably used as the metering device, which has a transverse bore in which a double-sided piston can be moved back and forth. When the dosing chamber under the channel is filled with a portion of the food, the rotary valve is turned through 180 ° and the portion is separated from the column. The portion is ejected downwards into a packaging container by a piston movement. The piston movement opens a second metering chamber at the top of the rotary valve. The axial movements of the blocks take place approximately according to the movement of the piston in the rotary valve. The volume of the metering chambers can be adjusted by changing the piston stroke.

Other metering devices can also be used, for example with metering chambers which can be displaced transversely to the channel.

• Fig. 1 zeigt eine Vorrichtung, bei der die Blöcke nach oben und auseinander geschoben sind,
• Fig. 2 zeigt eine Vorrichtung, bei der die Blöcke nach unten und zusammengedrückt sind,
• Fig. 3 zeigt eine andere Vorrichtung mit zwei Kanälen und als Drehschieber ausgebildeten Dosiereinrichtungen, wobei die Stellung der Blöcke und Dosiereinrichtungen für beide Kanäle verschieden gezeichnet ist.

Further details of the invention will be described with reference to the accompanying schematic drawings.

• 1 shows a device in which the blocks are pushed up and apart,
• Fig. 2 shows a device in which the blocks are down and compressed,
• FIG. 3 shows another device with two channels and metering devices designed as rotary slide valves, the position of the blocks and metering devices being drawn differently for both channels.

1 and 2, a channel 3 is arranged under a storage container 1 with an opening 2, which leads to a metering device 4 with a metering chamber 5 which can be displaced transversely to the channel 3. The channel 3 is formed by two fixed plates 6 and the wedge-shaped, movable blocks 7 and, like the metering chamber 5, has an approximately rectangular cross section. The blocks 7 can be moved on inclined sliding surfaces 8 between an upper position (FIG. 1) and a lower position (FIG. 2). The drive for the movement of the blocks 7 takes place by means of pneumatic devices and levers (not shown) which engage the pins 9 of the blocks 7. The blocks 7 are made of plastic. Its inner sides 10 facing channel 3 are profiled in a step-like manner. An upward movement of the blocks 7 increases the channel cross section, and a downward movement reduces it.

The food which is difficult to fill falls irregularly from the storage container 1 through the opening 2 into the channel 3 and forms a column 11. The upper part of the column is very loose. The lower part of the column, on the other hand, is evenly compressed due to the weight of the column on it and due to multiple movements of the blocks 7, so that the mass portioned volumetrically in the metering chamber 5 gives individual portfolios of largely the same weight. When the blocks 7 move upwards, the column 11 falls into the empty metering chamber 5 provided. When the blocks 7 move downwards, the column 11 is compressed and at the same time transported in the direction of the metering chamber 5. During this movement, the lower end of the column 11 is further compressed and the metering chamber 5 is completely filled. The dosing chamber is then pushed aside, the portion contained in it being separated from the column. As soon as the emptied metering chamber 5 is again under the channel 3, the blocks 7 are moved upward, so that the cross section of the channel 3 increases. The lower end of the column now no longer held laterally by the profiled inner sides 10 of the blocks 7 slides into the metering chamber 5 and is thereby compressed by its own weight. Here, the column 11 also expands in its cross section and in this way pulls further parts of the food from the storage container 1 into the channel 3. Since the force attack of the blocks 7 on the column 11 occurs only laterally, the food is compressed very gently. This also applies to the insertion into the metering chamber 5, because if the pressure at the lower ends of the blocks 7 is too strong, some of the food in the middle of the column 11 can escape upwards, which increases the compression in the lower end of the column.

In Fig. 1 it is indicated that the metering chamber 5 can move under lateral movement under a punch 12 which presses the measured portion into a box 13 on a transport device 14.

In the device shown in Fig. 3, the front of the two fixed plates 26 is removed, which e.g. is useful for cleaning the device. From the storage container 21, the food to be filled passes through two openings 22 into the two channels 23. Between the inclined sliding surfaces 28, which can also be seen as the outer side walls of the channels, the blocks 27 are movable. Guide flaps 39 are arranged in the upper end of the channels 23, which prevent parts of the food from falling onto the upper sides of the blocks 27 and strip off the parts adhering to the inner sides of the blocks 27 at the top.

The blocks 27 can be moved in both directions along the sliding surfaces 28. Their inner sides 30 are also profiled in steps, but the line of contact with these profiles is somewhat curved in such a way that in the two end positions of the blocks 27 the cross section of the channels 23 is larger at the top than at the bottom. The blocks 27 are driven by pins 29 in the upper end of the blocks which project through the rear fixed plate 26 and are connected here with levers, not shown, etc. Guide curves 36 for the pins 29 are arranged in the rear plate 26 and enable the upper ends of the blocks 27 to be lifted off. At the beginning of the downward movement of the blocks 27, they can initially be moved more strongly against one another (corresponding to the curved arrows A) than the lower ends, which are pressed together according to the inclination of the sliding surfaces 28 (as indicated by arrows B). The lower ends form fulcrums around which the blocks are pivoted during their displacement. During the upward movement, the blocks 27 are moved along the sliding surfaces 28 (according to the arrows C). The guide curves 36 limit the maximum movements of the blocks 27. If, however, a pressure builds up in the downward movement in the column or in the metering chamber, which, taking into account the lever ratio (not shown), is greater than the pressure of the drive medium in the pneumatic devices (also not shown) the pins 29 within the recess defined by the curves 36, without abutting the curves 36.

Dosing devices 24 are arranged below the channels 23. In the embodiment shown in FIG. 3, these consist of a rotary slide valve which is formed from a rotary body 37 rotated step by step by 180 ° with a double piston 38 which is displaceable in a channel transversely to the axis of rotation. When the piston 38 is displaced, the portion located in the lower metering chamber 35 is replaced by a Funnel 33 ejected into a packaging container 40, while at the same time the upper half of the piston 38 forms a second metering chamber 35, into which the lower end of the column (not shown in FIG. 3) can fall. The movements of the metering device 24 and the blocks 27 are to be coordinated with one another and are expediently carried out in such a way that the blocks 27 are only moved upwards when the channel 23 is closed after the rotary body 37 has been partially rotated, and that the downward movement of the blocks 27 is not before downward movement of the piston 38 begins.

The stroke of the piston 38 or the distance between its two halves can be adjustable in the metering device 24 in order to precisely adjust the volume of the upper metering chamber 35. In contrast to the illustration in FIG. 3, the dimensions of the metering chamber 35 can also be approximately the same as those of the packaging container 40.

1 and 2, the difficult-to-fill foodstuffs mentioned at the outset could be filled in portions of approximately 240 to 600 g of relatively low weight scatter and metering speeds of up to approximately 25 portions per minute. 3, metering speeds of up to 60 portions could be achieved in each of the two metering devices. However, the possible speed depends on the food and the permissible weight spread. In a packaging line for blanched spinach leaves, for example, a metering volume of up to 300 cm ^{3 is} filled at a rate of up to 45 portions per minute with each of the two metering devices according to FIG. 3.

The device is also characterized by a simple design and good cleaning options.

Claims (7)

1. Process for the dosing of products that are difficult to fill into packages, for example foodstuffs such as blanched spinach, andive, sliced grean beans, vegetable mixes, noodle mixes etc., into portions of uniform weight, in which the products to be packaged from a storage container are formed into a compressed column, are pushed into a dosing chamber of a volumetric dosing device and are divided into separate portions, characterized in that the compression of the column is effected by compressing it several times transversely to its axis, the column during or at the end of the compression being conveyed positively downwards and the lateral pressure on the column being only removed after the latter step.

2. Apparatus for carrying out the process according to claim 1, provided with a channel (3, 23) of variable cross-section arranged between a storage container (1, 21) and a dosing device (4, 24), said channel (3, 23) being arranged between two fixed plates (6, 26) forming opposite channel walls and two blocks (7, 27) or plates forming the two other channel walls and movable axially and towards each other, said blocks or plates having waved or stepped profiles on their sides (10, 30) facing the channel (3, 23), characterized in that the plates or the blocks (7, 27) are wedge-shaped and can be displaced on inclined sliding surfaces (8, 28), so that a displacement in the direction of the dosing device (4, 24) connected to the channel (3, 23) simultaneously results in a reduction of the cross-section of the channel, and that the channel (3, 23) is arranged downwardly and preferably perpendicularly.

3. Apparatus according to claim 2, characterized in that the angte.of inclination between each sliding surface (8, 28) and the central axis of the channel (3, 23) is 12 to 25° and the wedge angle of the blocks (7,27) between their side movable on the sliding surface (8, 28) and the line of contact at the waved or stepped profiles is also 12 to 25°, the blocks (7, 27) tapering in the direction of the dosing device (4,24).

4. Apparatus according to claim 2 or 3, characterized in that the upper ends of the blocks (27) or plates can be compressed at the start of the displacement in the direction of the dosing device (24) while being lifted off the sliding surfaces (28), the lower ends being capable of forming fulcrum points during the axial displacement, and the blocks (27) can be shifted back into the starting position while lying at full length on the sliding surfaces (28).

5. Apparatus according to any one of claims 2 to 4, characterized in that the heigth of the channel (3,23) is at least five times the depth of the dosing chamber (5, 35).

6. Apparatus according to any one of claims 2 to 5, characterized in that the length of the axial displacements of the blocks (7, 27) is at least about equal to the depth of the dosing chamber (5, 35).

7. Apparatus according to any one of claims 2 to 6, characterized in that the blocks (7, 27) can be displaced by pneumatic or hydraulic devices and the length of the displacement of the blocks (7, 27) on compression of the blocks can be limited in such a way that the pressure exerted by the column on the devices becomes greater than the adjustable driving pressure of said devices.

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