EP1362787B1 - Method and apparatus for filling bags with means for air extraction - Google Patents

Abstract

The bag filling process involves using a dosing device with a filling tube (11) for insertion in the bag, with a flange (12) at the top and a closing device (13) at the bottom to suck the air out of the material above the closing device via the inside of the filling tube before or during filling. Air may be admitted to the material from time to time via the filling tube with the closing device open.

Description

The invention relates to a method for filling bags with pourable, in particular powdery material by means of a metering device with a vertical filling tube immersible in the bag and a metering device for pourable, especially powdery material with a vertical filling tube having a controllable closure member at the lower end of the Has filling tube with which the filling tube to open and close. The filling tube is in this case arranged with its upper end to a feed hopper. The closure member comprises an adjustable in the direction of the vertical filling tube Verschließkonus which releases an annular gap at the lower end of the Füllrohes in an open position and rests in a closed position with its conical surface on an annular surface or annular edge at the lower end of the filling tube. The Verschließkegel can be attached directly to a coaxially inserted rotationally driven screw conveyor.

A method and a device of this type are known from DE 199 62 475 C2.

When filling bags with pourable material on the one hand, a rapid filling of the bags is desired to increase the capacity of a bottling plant, on the other hand, a precise dosage is required because quantities below target value are inadmissible and quantities with excessive dispersion above the target value are uneconomical. The two requirements for fast filling on the one hand and exact dosage on the other hand are in contrast to each other, since the former a large Volume flow and the latter requires a small flow rate. Therefore, the bags to be filled up to a certain filling amount of 90 to 95% of the target amount quickly filled with a large flow, the dispersion of the result obtained may be relatively large, and then ensured with a small flow of accurate filling, the few Percentage points above the target quantity.

A problem with previous filling techniques is that powdery materials accumulate during the filling process with air, this being done in an automatic way on the way from the bunker via a weighing device in the hopper, especially when in the hopper an agitator is used, which receive the flowability should. This disadvantageously forces the vented measured material in the bag to vent before closing the bag. Venting probes for this purpose are known for example from DE 34 14 218 C2. During the deaeration process, the volume of the filled material is reduced, so that an excessively long bag flag is created, which must first be shortened before closing the sack.

US Pat. No. 2,985,201 A discloses an apparatus and a method for degassing masses of small particles, such as powders or dusts. The device comprises a vertical housing tube with a driven drivable feed screw in which a plurality of screen cylinders rests coaxially with the housing tube. The annular space between the housing tube and the screen cylinders can be connected to a vacuum pump via a connection in the housing tube. The bottom outlet opening from the housing tube is constantly open.

From DE 25 53 879 A1 a packing machine for filling pourable material in a container is known, which has an at least partially porous inner tube to form an annular space in airtight vertical packing tube and at a distance from this, a suction port for connection to a Saugzugquelle and has a pressure port for connection to a pressure medium source. Within the Packrohres is a drivable packing screw. The packing tube is constantly open at the bottom.

On this basis, it is an object of the present invention to provide a method for filling a bag with means of the type mentioned, which makes it unnecessary to vent the measured material in the sack bag. The solution to this consists in a method in which air is sucked off at least before filling with closed closure member from the material above the closure member via the inside of the filling tube. This is a venting of the material takes place immediately before the flow of material from the filling tube, which can then no longer accumulate with air. It should be noted that the filling tube is already immersed in the bag opening or ends immediately above the bag opening. The venting should be done before the opening of the closing and can be continued during the outflow of material from the filling tube. This applies in particular to the process of coarse dosing and an optionally following medium coarse material flow.

During the subsequent fine metering, according to a preferred embodiment, air can be introduced into the material via the inside of the filling tube in order to increase the flowability. Since only very small amounts of material are supplied in this case, the proportion of air is correspondingly negligible. This means that a venting of this low proportion of air subsequently no longer needs to be done.

In an extremely advantageous manner can be used with the inventive method smaller bags for a certain amount of filling, which are placed or cut to the compact low-air volume of the material. This results in a corresponding cost advantage when purchasing the bags. The shortening of initially oversized sacks after venting deleted accordingly, so that a further saving in terms of the cutting device and the cost of the cutting process is effective. The stability of the bags filled with air-poor material is improved from the beginning, so that they are free-standing on a conveyor belt a closing or sealing device can be supplied. Likewise, the stackability is improved due to the denser low-air material.

A device according to the invention is characterized in that the filling tube comprises an outer tube and a strainer, which are coaxial with each other, wherein the annular space between the outer tube and the strainer tube is connected to controllable air suction means, which are used at least when the closure member is closed. In addition, the annular space between the outer tube and the sieve tube can be connected to controllable air supply means. The screen tube should in this case be arranged close to the outlet of the closure member and be effective, it may extend over the entire length of the filling tube or even over only a portion of the length. In the latter case, the strainer tube can be supplemented axially by a closed inner tube. The air extraction or the air task preferably takes place in the annular space between the outer tube and the inner tube. In an advantageous embodiment, it is provided that the strainer is located directly above the closure member and connects to the top of the sieve an inner tube of approximately the same diameter. Furthermore, it is provided that the screen tube consists of several layers of wire mesh. It is provided that the mesh size of the layers of wire mesh increases from the inside to the outside and that the mesh size of the inner layer has a minimum value of 1 micron and is in particular between 1 and 5 microns. In addition, it is provided that the screen tube is held by spacers in the outer tube having axial openings. Between the screen tube and the outer tube may be axial support body for the screen tube. It is further provided that the closure member comprises a Verschließkonus with upwardly facing conical surface, which rests adjustable in height against a attached to the lower end of the filling tube end ring. As mentioned, a screw conveyor is arranged within the filling tube, wherein the sealing cone carries a blading on the surface. Hereby, a fine metering can be effected by rotationally driving the sealing cone.

A preferred embodiment of the invention is shown in the drawing. A filling tube 11 with a vertical axis A has at the upper end Anflanschmittel 12 and The Anflanschmittel 12 consist of a nozzle 14, a flange 15 and a sealing plate 16. Stub 14 and sealing plate 16 form a funnel surface 17 flange plate 15 and sealing plate 16 can be screwed together at a hopper. In the socket 14, a threaded bushing 19 is inserted, which is secured against rotation in the socket 14 with locking pins 20. On an outer tube 21 of the filling tube 11, a threaded bushing 18 is placed, which is screwed into the threaded bushing 19. In the outer tube 21, an inner tube 22 is used, which is shorter than the outer tube 21. The inner tube 22 is centered in the outer tube 21 by means of centering rings 23, 24. The centering rings each have axial openings 25, 26 in a uniform circumferential distribution. The inner tube 22 carries at the upper end a connecting ring 29 and at the lower end a connecting ring 30. Between the inner tube 22 and the closure member 13 extends in the outer tube 21 an inventive screen tube 28 of approximately the same diameter as the inner tube 22. The screen tube 28 is between a upper connecting ring 31 and a lower connecting ring 32 held, which form with the outer tube 21 annular gaps 33 and 34. The screen tube 28 is centered by circumferentially distributed pressure rods 35, 36, which are inserted between the connecting rings 31, 32 in the outer tube 21 and axially relieved. By means of a closure ring 27, which is centered in the outer tube 21 and is the part of the closure member, the inner tube 22 and the screen tube 28 when screwing the threaded bushing 18 axially clamped in the threaded bushing 19 against the nozzle 14. Here, between the connecting piece 14 and the connecting ring 29, between the connecting rings 30 and 31 and between the connecting ring 32 and the end ring 27 each seals 45, 46 and 47 are inserted. In the end ring 27 sits a multi-part closure cone 37 with upwardly facing conical surface, which carries a seal 48 which rests directly against the ring 27. From its conical surface, the cone 37 has a blading 39. The multi-part cone 37 includes a lower retaining pin 40, a retaining plate 41, a Sicherungssplint 42 and a cover 43 for the Sicherungssplint 42. The cone 37 is fixedly connected to a screw conveyor 44 which is rotationally driven and axially adjustable held in the filling tube 11. The screw conveyor 44 is shown aborted above. The filling tube 11 is shown interrupted in the region of the inner tube 22 and the outer tube 21. By lowering the locking cone 37 by means of the screw conveyor 44, an annular gap at the bottom End of the filling tube 11 is opened, can flow through the material. By rotating the driving of the screw conveyor 44 while the material is promoted feindosierbar. In the nozzle 14, an air suction nozzle 38 is inserted radially. Already before opening and / or during the rotary driving of the screw conveyor 44, air is sucked out via the inner annular space between the strainer tube 28 and the inner tube 22 on the one hand and the outer tube 21 on the other hand. In a late phase of the fine dosing air can be supplied by pressure task.

Claims (14)

1. A method of filling a bag with a pourable, more particularly a powdery material, by means of a metering device with a vertical filler pipe (11) which can be introduced into the bag and which comprises flanging means (12) at its upper end and a controllable closing element (13) at its lower end with the help of which the filler pipe can be opened and closed,
   characterised in
   that, at least prior to filling the bag, air is extracted from the material above the closing element (13) via the inside of the filler pipe (11), with the closing element being in a closed condition.
2. A method according to claim 1,
   characterised in
   that, during the filling operation, with the closing element (13) being in the open condition, air is temporarily introduced into the material via the inside of the filler tube (11).
3. A metering device for pourable, more particularly powdery material, having a vertical filler pipe with flanging means (12) for being fixed to a feeding funnel, and with a controllable closing element (13) at the lower end of the filler pipe (11), by means of which the filler pipe can be opened and closed,
   characterised in
   that the filler pipe (11) comprises an outer pipe (21) and a sieving pipe (28) which are positioned coaxially inside one another, wherein the annular chamber between the outer pipe (21) and the sieving pipe (28) is connected to air extraction means which can be used at least when the closing element is in the closed condition.
4. A metering device according to claim 3,
   characterised in
   that the annular chamber between the outer pipe (21) and the sieving pipe (28) is connected to air supplying means.
5. A metering device according to any one of claims 3 or 4,
   characterised in
   that the sieving pipe (28) is positioned directly above the closing element (13) and that an inner pipe (22) with approximately the same diameter adjoins the upper end of the sieving pipe.
6. A metering device according to any one of claims 3 to 5,
   characterised in
   that the sieving pipe (28) consists of a plurality of layers of wire mesh.
7. A metering device according to claim 6,
   characterised in
   that the mesh size of the layers of wire mesh increases from the inside to the outside.
8. A metering device according to claim 7,
   characterised in
   that the mesh size of the inner layers amounts to at least 1 µm, more particularly to a value ranging between 1 and 5 µm.
9. A metering device according to any one of claims 3 to 8,
   characterised in
   that the sieving pipe (28) is held by spacing rings (31, 32) in the outer pipe (21), which spacing rings (31, 32) comprise axial apertures (33, 34).
10. A metering device according to any one of claims 3 to 9,
    characterised in
    that between the sieving pipe (28) and the outer pipe (21) there are positioned axial supporting members (35,36) for the sieving pipe.
11. A metering device according to any one of claims 3 to 10,
    characterised in
    that inside the filler pipe (11) there is arranged a conveyor worm (44).
12. A metering device according to any one of claims 3 to 11,
    characterised in
    that the closing element (13) comprises a closing cone (37) with an upwardly pointing conical face, the closing cone (37) height adjustably abutting a terminating ring (27) attached to the lower end of the filler pipe (11).
13. A metering device according to any one of claims 11 or 12,
    characterised in
    that the closing cone (37) is firmly connected to the conveyor worm (44).
14. A metering device according to any one of claims 12 or 13,
    characterised in
    that the closing cone (37) carries blades (39) on its conical face.

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