EP2097319B1 - Method and device for filling a container - Google Patents

Abstract

Method and apparatus for filling bags with loose materials, wherein a package to be filled is filled by means of a filling element through a filling process. The filling process comprises a filling stage, a settling stage, and a discharge stage wherein during the filling stage, loose material is filled into the bag while admitting air and in the settling stage, a settling phase is provided for the pressure to drop and in the discharge stage, the bag is discharged from the filling element. The filling process is shortened in that the available volume of the bag is reduced during the filling process to maintain the pressure prevailing in the bag high, while at the end of the filling process the available volume of the bag is expanded to rapidly reduce the pressure prevailing in the bag.

Description

The present invention relates to a method and a device for filling a flexible container, in particular a bag, with pourable materials and in particular with bulk materials, wherein the flexible container is filled by means of a filling member. The invention is used for filling of powdery products or granules and in particular for filling light and very fine powder products, such as aerosils, as well as used for color production carbon black particles or TiO ₂ particles or TiO ₂ containing materials or the like, in which the bulk material during filling contains a considerable amount of air. However, the invention is also suitable for filling other pourable or flowable materials or for filling toxic or environmentally hazardous products.

Various systems for filling bulk materials have become known in the prior art. In conventional systems for filling pourable goods into valve bags, the bulk goods contain a certain amount of air during filling. The air content contained in the bag is released slowly via corresponding openings in the bag wall to the outside.

Nevertheless, there is an overpressure in the bag during the filling process, which is for example about 150 to 250 millibars. This pressure is still in the moment of switching off the

Filler before. If now at the moment of switching off the bag is withdrawn from the filling member, the pressure prevailing inside the bag abruptly discharges over the still open valve, so that a certain and especially for lightweight materials significant amount of product is transported out of the bag with the outdoors , This leads to a weight loss of the bag and also to contamination of the system and the bags. During the filling of, for example, soot particles or TiO ₂ particles, even small amounts of escaping product lead to a very considerable pollution of the environment.

In order to reduce the product leakage and to increase the cleanliness of the equipment and the sacks, it is therefore in the prior art before waiting for the bag to wait until the pressure inside the bag has degraded over the wall, or the pressure must be via a bypass be dissipated. The pressure reduction over the wall requires a considerable amount of time, in particular for light bulk goods, so that a drastic reduction of the filling performance must be expected. If the pressure is removed via a bypass, the pressure reduction is accelerated, but does not prevent product from being discharged through the bypass, which then leads to a weight loss of the bags. This also results in significant weight fluctuations. In addition, the escaping product usually has to be discarded. Overall, this condition means an increase in operating costs.

In the prior art are with the US 3,533,454 a method and an apparatus have become known according to the Obergegriffen of claims 1 and 13, with which materials are filled in bags. During the filling process, the lateral surfaces of the bag are first pressed in. During the filling process, the side walls are then expanded so that the pored sidewalls of the bag do not become clogged during the filling process by the filling material. This should be done during the filling process, a continuous venting. By the constant bleeding, the filling rate can be increased during filling. This known technique only leads to a relatively small shortening of the entire filling process, because this is considerably determined by the maximum pressure in the bag at the end of the filling process and the resulting waiting time after the end of the filling process. Since the maximum pressure is unchanged, the waiting time remains unchanged and only a small shortening of the filling process is achieved.

In the prior art is further with the DE 195 41 975 A1 a method and an apparatus for forming and venting open bags after the filling process has become known in which the upper edges of the projections of the bag wall are clamped in a slidable manner with clamping jaws and in which, after filling, the clamping jaws are rolled in the direction of the filling material level present in the bag; to remove the contained air from the sack via a lance inserted through the upper opening of the sack and subject to vacuum. This can effectively shorten the waiting time. A disadvantage of the known device is that not only air, but also filling material is discharged through the introduced into the bag lance.

From the DE 37 03 714 A1 a bagging machine for filling powdery goods has become known with a filler neck, in which at the filler neck provided with a filter and connected to a vacuum source air outlet opening is provided which serves to extract the air contained in the bag. With such a device powdery bulk materials can be filled into valve bags. A disadvantage of the known device, however, is that when using a coarse-pore filter material still a significant proportion of contents is discharged through the outlet, while using a fine-pored filter material, the pores quickly through the contents, so that the effect is significantly reduced.

In such devices known from the prior art, wherever the product can escape with the air, the sack must therefore be overfilled with the expected weight loss in order to reduce or compensate for the weight deviations of the filled sack. However, since diester weight loss varies, a greater dispersion of the weights is inevitable, which must be filled to maintain a minimum weight usually more material in the bags, as would actually be necessary. Alternatively, the settling time can be extended after the end of the filling process to reduce the overpressure.

In all cases described, a procedural disadvantage arises, which is a noticeable increase in costs due to a significant reduction in performance and / or material loss.

Compared to the cited prior art, it is therefore an object of the present invention to provide a method and an apparatus available with or with which a rapid filling of flexible containers is possible, with the decrease only a small or even virtually no Weight loss occurs.

This object is achieved by a method having the features of claim 1. The device according to the invention is the subject of claim 13. Preferred developments of the invention are the subject of the subclaims. Further advantages and features emerge from the exemplary embodiment.

The method according to the invention is intended for filling flexible containers with pourable goods and is preferably used for filling bags with especially light pourable goods. The container to be filled is filled with a filling member or with several filling members by means of a filling process. The filling process comprises at least one filling section, a calming section and a removal section. At the end of the filling process, the volume of the container and in particular the volume available to the container is increased according to the invention in order to reduce the pressure prevailing in the container.

During the filling section, at least one pourable material is filled into the container, in particular with the addition of air. At least one calming-down phase is provided in the calming section for depressurization, and in the detaching section the container is removed from the filling device. Optionally, a welding of the bag can take place. The filling process according to the invention is shortened by the fact that the available volume of the container is reduced during a substantial part of the filling process, so that it is smaller than the possible volume of the container in order to keep the pressure prevailing in the container high during filling , At the end of the filling process, the available volume of the container is increased in order to quickly reduce the pressure prevailing in the container.

For the purposes of this application, the term "filling process" is understood to mean the process from putting on or arranging the container until the removal or removal of the filled container. The filling process comprises in particular the placement or attachment of the container, the actual filling of the container and the removal of the filled container.

The term "filling process" is understood to mean the process of filling, that is to say the filling section. For the purposes of this application, the term "during the filling process" is understood to mean that the volume in terms of time after the start of the Filling process, that is done after arranging or plugging and before the removal of the container.

Another significant advantage of the invention is the increase in volume at the end of the filling process, whereby the overpressure is reduced accordingly. By increasing the volume available to the container, the pressure prevailing in the container is reduced directly in proportion to the increase in volume, so that with the increase in volume directly a pressure reduction is achieved since the flexible container will immediately take up the increased volume due to the increased internal pressure. Consequently, the take-off pressure can be quickly reached, so that the decrease of the container no high loss of material arises because the pressure inside the container is reduced by the increase in volume.

Another advantage of the method according to the invention is a better bag ventilation already during the current filling process. Basically, a bag starts to vent when there is overpressure, ie when there is a pressure difference to the environment. This time typically occurs from about 50% of the weight to be filled. Due to the fact that initially only a reduced volume is available in the method according to the invention, the pressure level in the bag rises steeper during the filling process than in a conventional method, so that an overpressure in the bag is achieved at a considerably earlier point in time, which is an automatic bag venting causes. Since the venting rate of the container depends on the pressure difference between the interior of the bag and the environment, there is optimal ventilation due to the high overpressure level prevailing during the filling section. The venting of the container is significantly accelerated.

Applying the pressure prevailing in the sack over time, the area under the curve is a measure of the work of venting. This area, which refers to the period of the actual filling, is greater in the inventive method, so that according to the invention a faster filling can be achieved.

First experiences in a specific case have shown that overpressure is already reached there after about half of the time otherwise required, so that effective ventilation takes place during the filling process even over a much longer period of time.

According to the invention, the volume is increased towards the end of the filling process, in particular at the end of the filling section or in the settling section after the filling process has ended, while the container is still arranged on the filling nozzle or the filling member. If, for example, the volume available to the flexible container is increased immediately after switching off the filling element, this means a directly proportional reduction of the internal pressure in the container so that the container can either be removed directly or the required waiting time is considerably reduced. In one specific case, the duration of the settling phase was reduced from about 20 seconds to 5 seconds, while the duration of the filling section remained constant at about 30 seconds, so that the time for the filling process could be reduced by 20 to 30%.

Preferably, the available volume is kept substantially constant during the filling section. Advantageously, a predetermined pressure in the container is built up quickly and then held approximately during the filling. The built-up pressure can be the maximum buildable Pressure or a pressure that is chosen in compliance with safety tolerances.

The available volume can be increased in the calming section only after a calming phase to promote the venting.

In all embodiments and developments, the pressing jaws are preferably pressure-controlled.

In a preferred embodiment, the contact pressure of the pressing jaws in the calming section is initially increased for a period of time after the end of the filling section, before the available volume is subsequently increased by reducing the contact pressure of the pressing jaws. As a result, the ventilation is further enhanced at the elevated pressure level, so that the calming section can be shortened.

In one embodiment of the invention, a characteristic value for the weight of the container or of the contents contained in the container is detected during the filling process, in particular during filling or during the filling process at periodic intervals or continuously. In this case, the weight can be determined via a net method, and particularly preferably a gross method. It is also possible that a bag chair, on which the container is arranged, is part of the weighing system. Since the weights of the components involved are known, it is possible to deduce from the measured total weight on the current weight of the contents contained in the container back.

Preferably, when the target weight of a container is reached, the feed of the bulk material is stopped. Also possible is a weight-dependent control of the filling process or the filling process, wherein the filling rate when reaching a predetermined Weight or weight fraction of the coarse flow rate is reduced to the Feinstromfüllrate. The filling rate can also be lowered continuously on reaching a predetermined weight or weight fraction up to a minimum filling rate in order to achieve optimum filling.

In a preferred embodiment of the invention, the volume available to the container is increased when a predetermined weight or a predetermined proportion by weight is reached. The increase in volume can take place in particular abruptly or approximately abruptly. In all embodiments, the available volume in the calming section may be in a short period of time, e.g. be enlarged in one step or abruptly. Also possible is a continuous increase in volume after completion of the filling section.

In this embodiment and in all other embodiments, the volume available to the container can be limited initially preferably by lateral limiting devices, pressing devices, pressing jaws of the like, the pressing jaws or the like to increase the available volume of the container then at the end of the filling process and in particular be driven outward in the calming section. In preferred embodiments, the limiting devices or pressing jaws or the like act on the longitudinal sides of the container.

For example, the pressing device can initially limit the volume available to the container, so that it is smaller than the possible volume of the container. In the calming phase then the pressing devices or the like can be removed from the container or moved away, so that the container expands due to the prevailing internal pressure, whereby the internal pressure in the container is reduced accordingly becomes. The enlargement of the volume available to the container can take place abruptly or continuously or stepwise.

In preferred developments of the invention, the volume available to the container is increased by up to 50% or more, in particular by up to 30%. Preferably, the volume increase is between about 3% and 20% and more preferably between about 5% and 15%. Depending on the material to be filled, the percentage of particularly fine and light fabrics may be even greater.

If towards the end of the filling process there is an overpressure of e.g. 100 millibars so the internal pressure is about 1.1 bar. By increasing the volume by 10%, the overpressure contained in the bag can be completely reduced, for example. At higher pressures, an almost complete pressure reduction can be achieved even with a volume increase of 10%, if after stopping the filling a short waiting time is inserted, within which the pressure is automatically reduced by the openings contained in the bag by a certain amount. According to the invention, the waiting time and the calming section can be shortened considerably.

Preferably, after stopping the filling member, first the waiting time is inserted and then the volume is increased, since the pressure reduction in the preceding period is faster at higher overpressures.

In all embodiments of the invention, a characteristic value for the filling pressure in the container can preferably be detected by means of a pressure sensor. In particular, a characteristic value for the air pressure prevailing in the container is determined. For example, a probe with a measuring channel can be provided on a filling element designed as a filling tube or filler neck, which extends into the interior of the container to be filled so that a sensor connected to the measuring channel acquires a characteristic value for the pressure prevailing in the container. In other embodiments, a characteristic value for the pressure prevailing in the container can also be derived via a sensor connected to the filling element or to the container.

Advantageously, the filling process as a whole or at least the filling process is controlled as a function of the determined characteristic value. This allows compliance with limits during the filling process. Preferably, the filling process is controlled such that a predetermined maximum pressure is not exceeded, e.g. to avoid a sack break. On the other hand, the filling member is preferably controlled such that the pressure present in the container or in the bag is as close as possible to the maximum pressure in order to accelerate the filling process as a whole.

In preferred developments of the invention, the volume available to the container is varied at least over a period of time as a function of the determined characteristic value for the filling pressure prevailing in the container.

If a pressure sensor is provided for determining a characteristic value for the filling pressure prevailing in the container, the time of acceptance of the container from the filling member or the filling nozzle is preferably selected as a function of the filling pressure, in order to limit the amount of leaking filling product during the removal.

In all embodiments, in particular valve bags are filled, which are closed after the filling or can also be executed self-closing.

In all embodiments, a diaphragm pump is preferably used to convey the bulk goods. Although the diaphragm pump is basically a machine for the conveyance of liquids or gases, this system has also proven itself for the conveyance of free-flowing goods and in particular of free-flowing goods.

The operating principle of the diaphragm pump is similar to that of the piston pump, with the diaphragm pump being completely separated from the bulk material to be filled and the drive. The separation is achieved by a membrane, by which the moving mechanical components of the engine are shielded from the effects of the bulk material to be conveyed.

The actual mechanical drive of the diaphragm pump can conventionally be effected via an electric motor by means of a connecting rod fixed to the diaphragm or by means of suitably controlled compressed air.

Diaphragm pumps have the advantage over conveyor turbines that they have a lower dependence of the filling capacity of the pressure prevailing in the bag overpressure, so that the prevailing during the filling process increased pressures affect the flow rate only slightly.

Preferably, double diaphragm pumps are used, which can also be controlled by compressed air. For this purpose, a double housing is provided, which contains two connecting membranes via a connecting rod. The membranes are acted upon on the outside by the conveying bulk material and on its inside by compressed air. About the connecting rod, a valve is actuated, which reverses the compressed air to the other membrane when reaching an end position. Such a diaphragm pump controlled by compressed air transfers the air pressure directly to the bulk material to be conveyed. By a Throttling the pressure, the transported amount of bulk material can be adjusted well.

In all embodiments, in particular light bulk material with a density of less than 300 kg per m ³ or with a density of less than 300 g per dm ^{3 is} sensed. Preferably bulk material is filled with a density of less than 250 kg per m ³ and in particular with a density between 30 and 150 kg per m ³ .

The inventive device for filling flexible containers is provided in particular for filling bags with pourable goods and comprises at least one Füllergan with which a container to be filled by means of a filling process is filled in particular with the addition of air. The filling process comprises at least one filling section, a depressurization settling section and a take-off section. In this case, a pressing device or a limiting device is provided, with which the volume provided for the container can be changed. Furthermore, a control device is provided. The device is characterized in that the control device is suitable and structured to shorten the filling process in that the control device controls the pressing device such that the volume available to the container is reduced during a substantial part of the filling process by means of the pressing or limiting device so that it is smaller than the possible volume of the container, and greatly increased at the end of the filling section, to keep the pressure prevailing in the container high during the filling section and to shorten the calming section after the filling section.

With the device according to the invention, which is particularly suitable for carrying out one of the methods described above, in particular valve bags can be filled effectively, wherein the volume increase after the filling section enables effective filling of the bags. Advantageously, pressing jaws are used as parts of the pressing device, which act on the container from the sides.

Advantageously, a pressure sensor is provided which determines a characteristic value or a characteristic value for the pressure prevailing in the container.

Preferably, the device comprises a comparison device for comparing the pressure prevailing in the container with a predetermined pressure or limit, so that at the end of the filling process, a decrease signal is triggered when the pressure prevailing in the container is less than or equal to the predetermined pressure.

Advantageously, the device has a membrane or double membrane pump for transporting the bulk material.

Further advantages and applications of the invention will become apparent from the embodiments which are described below with reference to the accompanying figures.

Fig. 1

eine schematische Darstellung einer erfindungsgemäßen Vorrichtung;

Fig. 2

eine weitere erfindungsgemäße Vorrichtung in einer per- spektivischen Ansicht;

Fig. 3

eine perspektivische Ansicht der Presseinrichtung nach Figur 2;

Fig. 4

eine Vorderansicht der Presseinrichtung nach Figur 3;

Fig. 5

eine Seitenansicht der Presseinrichtung nach Figur 3;

Fig. 6

eine schematische Schnittdarstellung durch ein Füllrohr einer erfindungsgemäßen Vorrichtung; und

Fig. 7

eine stark schematisierte Darstellung des Drucks und des Gewichts über der Zeit während eines Füllprozesses.

Show:

Fig. 1

a schematic representation of a device according to the invention;

Fig. 2

a further device according to the invention in a perspective view;

Fig. 3

a perspective view of the pressing device according to FIG. 2 ;

Fig. 4

a front view of the pressing device according to FIG. 3 ;

Fig. 5

a side view of the pressing device according to FIG. 3 ;

Fig. 6

a schematic sectional view through a filling tube of a device according to the invention; and

Fig. 7

a highly schematic representation of the pressure and the weight over time during a filling process.

With reference to the FIGS. 1 to 7 Now, an embodiment of the invention will be explained. In the FIG. 1 shown inventive device 1 is executed here in the embodiment as a rotating packaging machine, which is driven in the direction of arrow 21. The packing machine 1 is used to fill sacks 4 with pourable filling goods 18 and is executed here fully automatically in the embodiment.

The packaging machine 1 comprises six filling tubes 3, onto which the valve sacks 4 with openings 25 are pushed. As indicated by the arrow 22 in FIG FIG. 1 symbolizes the valve bags 4 are removed using a slip-on device, not shown, or coming from a stock of hand and pushed onto the filling tubes 3 or shot.

During one or more revolutions, the valve bags 4 are filled and removed after reaching the predetermined degree of filling at a predefined angular position. The valve of the valve bags 4 is closed and the bags are thrown onto the discharge belt 26, where the actually achieved weight of the valve bags 4 can be checked again before the valve bags 4 are removed.

As in FIG. 1 shown, each filling tube 3 is associated with a pressing device 5, each comprising two pressing jaws 5a and 5b. When attaching the pressing jaws 5a and 5b are moved apart, so that the valve bag 4 can be easily pushed onto the filling tube 3. Subsequently, the pressing jaws 5a and 5b are moved from the side of the valve bag, so that the for the valve bag available volume 2 (see. FIG. 4 ) is reduced from the beginning of the filling process and is smaller than the possible bag volume of the valve sack. 4

During the rotation of the valve sack 4, the sack is filled with the filling material 18 during the filling section 40 until the intended sack weight ml is reached. A highly schematized and only principally applied course of the bag weight 30 and the pressure 31 prevailing in the bag is over the time T in Fig. 7 shown. During the filling section 40, an overpressure has built up in the valve bag 4, which is typically up to 100 or 250 millibars and may even be greater and depends on the filling material and the other conditions. Due to the overpressure, the sack 4 expands as far as possible and occupies the maximum available volume, which, however, is initially limited by the pressing jaws 5a and 5b.

The filling process is stopped at time t1 when the intended bag weight ml is reached. After a short settling time, during which the inner bag pressure slowly degrades, the pressure can be increased by the pressing jaws 5a and 5b at time t2. The pressure in the bag thereby increases from the pressure 33 to the pressure 34 and then decreases along the curve 37, since the increased internal pressure causes a faster venting of the bag.

At time t3, the pressing jaws 5a and 5b are raised during the pressure 35, so that the volume available for the valve sack 4 between the pressing jaws 5a and 5b is increased abruptly. The valve bag 4 now assumes its maximum volume due to the overpressure prevailing in the interior of the valve sack 4, as a result of which the pressure prevailing in the interior of the valve sack 4 is correspondingly reduced. This leads to the fact that directly after the opening of the pressing jaws 5a and 5b, the inner bag pressure 36 is equal to the decrease pressure p1, so that at the time t4 the bag can be removed. After acceptance, an optionally decreases remaining pressure abruptly, so that the ambient pressure is reached, which is illustrated by the point 38.

The calming section 41 can thereby be considerably shortened. The additional pressure increase to the value p3 can, but does not have to be carried out.

In contrast to the representation after Fig. 7 the filling section 40 is usually subdivided into a section with coarse flow filling and a subsequent section with fine flow filling. For clarity, the in Fig. 7 not shown.

Due to the filling process, the necessary waiting time until the valve bag 4 can be removed from the filling tube 3, significantly reduced, so that the filling rate increases over conventional filling. At the same time, as the internal pressure is reduced, the discharge of the material from the filling pipe 3 decreases, so that the valve bags 4, the packing machine 1, and the surroundings are not so heavily soiled.

With the packing machine 1 according to the invention, preferably lightweight materials and in particular aerosils, carbon black and other light products are filled. However, it is also possible to use other products such as To fill cement or the like with the packaging machine 1 according to the invention.

According to previous experience in filling with light filler materials, such as fumed silica, results in a significant increase in performance with higher weight accuracy. While the waiting time after the end of the filling process during which the overpressure in the bag is reduced in conventional machines with a filling material between about 15 and 20 seconds, in the inventive system, the bag can be almost or even removed directly after the bag available volume was increased. The time savings is about 12 to 17 seconds per bag in this example. With an average duration of filling of about 30 seconds, this means a shortening of the filling process from about 50 seconds to about 35 seconds and thus a very significant increase in plant capacity by about 20 or 30 - 40%. With heavier materials or with materials that are filled with a lower air content, a lower performance increase may occur.

In FIG. 2 another packaging machine 1 according to the invention is shown in a perspective view, which is designed here as a stationary machine and not as a rotating system. The bag chair 20 is part of the weighed system in the so-called gross weighing method, in which the bag chair 20 and the pressing device 5 and the valve bag 4 to be filled with are weighed to from the weight determined on the contents contained in the valve bag 4 18 (see. Fig. 6 ), since the weights of the sack chair and the other components involved are known.

The pressing device 5 comprises a right pressing jaw 5a and a left pressing jaw 5b, which are arranged in the starting position, for example approximately parallel to each other and spaced from each other and which are pivotally mounted here at the lower ends of pivot axes 7. The two pressing jaws 5a and 5b are connected to each other at the upper ends via an upper linkage 5d, on which a motor 6 is arranged. By actuating the motor 6, the upper distance between the pressing jaws 5a and 5b is reduced, so that the volume 2 present between the pressing jaws 5a and 5b is influenced, as in particular also in the illustration according to FIG FIG. 4 is recognizable. As an alternative to the motor 6, another actuator for actuating the pressing jaws may be provided, which comprises, for example, a compressed air cylinder or hydraulic drive.

Instead of the rotatable bearings at the lower ends of the pressing jaws 5a and 5b, which are respectively provided with pressing plates 5c, can also be the lower linkage 5e via a motor 6 or other actuator designed to be adjustable in length.

By length-adjustable linkage 5d and 5e, a parallel displacement of the pressing jaws 5a and 5b can be achieved.

According to the invention, the pressing jaws 5a and 5b of the sack chair 20 are brought to the valve bag 4 at the beginning of the filling process or the filling process in such a way that they reduce the available sack volume 2 during the filling by, for example. Reduce 10%. That is, for a weight size of e.g. 10 kg only a reduced volume is available. Now, if the valve bag has reached its desired weight and the filling process is thus completed, the valve bag 4 is initially under the usual pressure of e.g. 100 or 250 millibars or so. At this moment, however, the two lateral pressing jaws are moved apart, so that the volume available to the valve bag 4 is increased virtually abruptly and thus the overpressure is compensated.

After moving apart of the pressing jaws 5a and 5b, the valve bag 4 can therefore be removed without a harmful loss of product occurring during the decrease. Consequently, this system allows a high filling performance, since no or only a short residence time is required after the filling process, wherein no 18 or only small quantities are discharged during the decrease.

In preferred embodiments, the packing machine comprises a double-diaphragm pump for conveying the filling material 18. A double-membrane pump 16 is suitable in particular for filling lightweight filling materials 18. The filling performance of filling materials having a bulk density of less than 100 g per dm ³ is about 60 sacks per hour and filler, but can also be larger or smaller.

It should be noted that not only rotating packaging machines 1 can be provided according to the invention, but it can also packaging machines 1 are used with only one filling tube or with several in-line filling tubes.

In the filling process, the control of the filling process is carried out by a balance control, which controls the filling speed in dependence on the already present in the valve bag 4 filling weight. In this case, a higher material flow, the so-called coarse flow, is usually first introduced until a predetermined proportion by weight is reached. Subsequently, the so-called fine flow is filled with a significantly reduced flow of material until the desired final weight ml of the valve sack 4 is reached.

An advantageous embodiment of the invention will now be with reference to the FIG. 6 described. In FIG. 6 a schematic cross section through a filling tube 3 is shown. In contrast to the previous embodiment, the packing machine 1 is after FIG. 6 additionally associated with the filling tube 3 at least one pressure sensor 10, with which a characteristic value for the pressure prevailing in the valve bag 4 pressure can be detected.

In FIG. 6 a filling tube 3 is shown cut, on which a valve bag 4 is pushed with its opening 25. The valve bag 4 is held with a mounted on an outer side 3 a of the filling tube 3 Blähmanschette 27 and sealed to the environment. In the inflated state, the inflation sleeve 27 engages an inner wall 28b of a portion 28 of the valve sack 4 which serves to fasten the valve sack 4 to the filling tube 3.

By means of the pressing device after the Figures 3 - 5 the volume 2 available for the valve bag 4 is reduced even before the beginning of the filling section.

Furthermore, a value characteristic of the pressure in the valve bag 4 is received via the pressure sensor 10 during the filling process. In this case, the pressure sensor 10 may be arranged in a region 3 c of the filling tube 3, which directly adjoins a region 3d occupied by the section 28 of the valve sack 4. The pressure sensor 10 extends through a wall of the filling tube 3, so that it receives the pressure in the interior of the filling tube 3, which essentially corresponds to the pressure prevailing in the valve bag.

Alternatively, a pressure sensor 10 may be provided which receives the pressure prevailing in the interior of the bag via a pressure receiving opening 9 or a measuring channel or a measuring line 13. The pressure receiving opening 9 may e.g. be provided in a front region of the filling tube 3 in the vicinity of the outlet opening for the filling material 18. The measuring line 13 may have a first channel 13 as a running portion in the filling tube and a second portion 13 b, which is designed as a flexible or rigid conduit and is connected to the pressure sensor 10. Since pressure disturbances propagate at the speed of sound, the measuring line 13 can have a considerable length.

The pressure values measured with the pressure sensor 10 are temporarily stored in the assigned digital evaluation unit 11 and transferred to a central control unit 14. Based on the data measured by means of the weighing system 12 and by means of the pressure sensor 10, the filling process is controlled. The measured values measured by the weighing device 12 are sent to an electronic processing unit 15, which is connected to the central control unit 14, which controls the conveying member 16.

For special substances or in special situations, air may be supplied via an air supply 17, e.g. Caking to solve.

The filling process works as follows. After attaching a valve sack 4 by hand or with a slip-on machine on a filling tube 3, the valve bag 4 is fixed by means of the Blähmanschette 27 and it the press jaws 5a and 5b are brought to the bag to limit its available volume. Subsequently, the filling process is started, which is controlled by the electronic control unit 14 and in which the filling material 18 and at the same time an air portion 19 are introduced into the bag 4.

The filling material 18 supplied to the conveying member 16 from a silo or the like is introduced through the filling tube 3 into the valve bag 4. The amount of filled material 18 is continuously detected by the weighing device 12 shown only schematically and the measured values are forwarded to the processing unit 15 and the control unit 14.

At the same time, the pressure prevailing in the valve bag 4 is detected. If the pressure in the valve bag exceeds a predetermined limit, the filling process is slowed down to avoid bursting of the valve bag 4. Conversely, the filling rate can be increased if the pressure prevailing in the valve bag is less than a predetermined pressure.

The position of the pressing jaws is controlled as a function of the current weight and the determined pressure in the valve bag 4. It is possible, e.g. that the pressing jaws 5a and 5b first reduce the volume available to the bag when a predetermined proportion of e.g. 30 or 50% of the intended capacity was filled in the bag. It is also possible, the pressing jaws 5a and 5b after the end of the filling process continuously to move apart to increase the volume available to the bag continuously.

Preferably, the pressing jaws are moved apart after the filling process, so that the pressure in the bag interior drops abruptly. Now, if the over-pressure determined inside the bag falls below a predetermined or selectable value, the bag is removed. Since there is no or only a slight overpressure during the removal, only very little or no filling material 18 is blown out of the bag during the removal, so that the sacks 4 and the packaging machine 1 remain cleaner.

Claims (15)

1. A method for filling flexible packages (4), in particular for filling bags (4), with loose materials (18), wherein by means of a filling element (3) a package to be filled (4) is filled by way of a filling process, which filling process comprises at least a filling stage (40), a settling stage (41) and a discharge stage (42), wherein during the filling stage (40) at least one loose material (18) is filled into the package (4) and wherein during the settling stage (41) at least one settling phase (37) is provided for pressure decrease, and wherein during the discharge stage (42) the package is discharged from the filling element (3),
   characterized in
   that the filling process is shortened in that during a considerable portion of the filling process the available volume (2) of the package (4) is reduced so as to be smaller than the possible volume of the package (4) to thus maintain a high pressure inside the package (4), while at the end of the filling process the available volume (2) of the package is expanded (4) to rapidly reduce the pressure prevailing in the package (4).
2. The method according to claim 1, wherein the volume (2) is maintained substantially constant during the filling stage (40).
3. The method according to any of the preceding claims wherein during the filling stage (40) a specified pressure (p2) is rapidly built up in the package and subsequently roughly maintained.
4. The method according to any of the preceding claims wherein the volume (2) in the settling stage (41) is expanded following a settling phase (37) wherein the volume (2) is preferably greatly expanded in one step in the settling stage (41).
5. The method according to any of the preceding claims wherein a parameter for the weight of the package (4) is captured during the filling stage (40) and as the target weight (m1) of the package (4) is attained, feeding of the material (18) is cut off.
6. The method according to any of the preceding claims wherein the available volume (2) is expanded up to 30%, in particular between 5% and 15%.
7. The method according to any of the preceding claims wherein the available volume (2) is influenced by means of lateral squeezing jaws (5a, 5b) which act in particular on the longitudinal sides of the package (4) and which are displaced outwardly for expanding the available volume (2).
8. The method according to any of the preceding claims wherein the squeezing jaws (5a, 5b) are pressure-controlled.
9. The method according to any of the preceding claims wherein the contact pressure of the squeezing jaws (5a, 5b) is first increased in the settling phase (41) after the filling stage is terminated (40) before the available volume is expanded by means of decreasing the contact pressure of the squeezing jaws (5a, 5b).
10. The method according to any of the preceding claims wherein a pressure sensor (10) captures a parameter for the filling pressure (31) in the package (4) and the filling process is controlled in dependence on the filling pressure (31).
11. The method according to any of the preceding claims wherein the volume (2) is varied at least during a time period (40, 41) in dependence on the filling pressure (31) and/or wherein the discharge time (t3) is selected in dependence on the filling pressure (31).
12. The method according to any of the preceding claims wherein a diaphragm pump (16) is employed for conveying the loose materials (18) and/or wherein the loose materials (18) have a low density and in the filling stage (40) during filling, a high air content.
13. An apparatus (1) for filling packages (4), in particular for filling bags (4) with loose materials (18) wherein a package to be filled (4) is filled by way of a filling process by means of a filling element (3) wherein the filling process comprises at least a filling stage (40), a settling stage (41) for pressure decrease and a discharge stage (42), wherein a squeezing device (5) is provided by means of which the volume (20) available for the package (4) can be varied, and wherein a control device (14) is provided which is suitable and structured to shorten the filling process in that the control device (14) controls the squeezing device (5) such that by means of the squeezing device (5) the available volume (2) of the package (4) is reduced during a considerable portion of the filling process and greatly expanded at the end of the filling stage (40) to maintain a high pressure in the package (4) during the filling stage (40) and to shorten the settling stage (41) following the filling stage (40).
14. The apparatus according to the preceding claim wherein at least one pressure sensor (10) is provided by means of which a parameter for a pressure prevailing in the package (4) can be determined and wherein a comparator device (14) is provided which compares the prevailing pressure (31) against a specified pressure (p1) and which triggers a discharge signal when the prevailing pressure (36) is beneath the specified pressure (p1).
15. The apparatus according to any of the two preceding claims wherein at least one diaphragm pump (16) is provided for conveying the loose materials (18).

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