EP0115069B1 - Method and apparatus for packing fibre flocks into bales - Google Patents

Description

The invention relates to a method for packaging fiber flakes in bales of the same weight as possible and suitable devices therefor.

For a long time, for example, the fiber manufacturer has been striving to pack its products in bales of the same weight as possible. Matching bale weights make it easier for customers to make arrangements, and they also produce reproducible results for the fiber manufacturer under optimal conditions.

There has been no shortage of attempts to derive the filling quantity for a bale from measured variables during bale production. Suitable for this once appears to be the force absorption of the press ram until a certain position of the ram is reached and / or the measurement of the time which is necessary using a certain given force until a certain position of the ram of the press has been reached. Experience has shown that such measurement methods are only sufficient to reach a specific setpoint within wide tolerance ranges of e.g. B. to comply with ± 20 kg.

A combination of different measurement methods of this type has been disclosed in German Patent No. 24 60 213, where in addition to a pressure sensor, at least one position sensor is also used.

Another approach was taken, for example, in German Offenlegungsschrift 28 19 807, where the fiber flake obtained is weighed in batches in a chute. This method is also only suitable to hold a rough estimate of the weights, since this weighing method is associated with a number of errors.

More precise methods and devices are described, for example, in German Offenlegungsschrift 28 49 900. Here, a special weighing device is provided in front of the pre-press, which first collects the incoming fiber flake in batches in a precisely working weighing device, only to then feed it to the pre-pressing. Such an additional weighing device is extremely complex in the form disclosed.

A direct weighing of the deposited fiber material has never been attempted. The reasons for this are obvious. Usually, the press box used in the pre-press is part of a carousel press, i.e. a free movement of the press box in the vertical direction, as would be necessary for weight determination, is not possible for equipment reasons alone. In addition, a direct use of force measuring devices in the pre-press would also always have the disadvantage of a low sensitivity or a large relative error, since such force measuring devices would not only have to absorb the weight of the press container and the deposited flake, but also the force of the press ram.

The German Offenlegungsschrift No. 29 11 958 describes for the first time the use of transportable press containers which no longer have a rigid connection to the primary or main press system.

The object was therefore still to find a method and a device for packaging fiber flakes in bales of uniform weight, in which only minor changes to the devices used are necessary, but in particular a complicated weighing mechanism before the pre-press can be avoided.

This problem was solved by a novel method and additional devices on the pre-press, starting from pre-presses as described in German Offenlegungsschrift No. 29 11 958, i.e. especially of pre-presses that work with a transportable press container that has no fixed connection to the pre-press or a downstream final press.

It is known to pack fiber flakes in bale form by multi-stage pressing, the fiber flakes being fed in batches with the help of a scraper from a filling shaft into a transportable press container and after several such pushes of the scraper, the fiber material accumulated in the transportable press container by the use of a press ram is compressed. After removing the press ram from the press container, additional flakes of fiber are added in batches to the pre-press or the transportable press container with the help of the scraper. The press container filled with pre-pressed fiber flake is then fed to a central press for final pressing. According to the invention, after moving an empty press container into the pre-press, this transportable press container is first subjected to weighing, the press container being lifted from its base by lifting devices and being carried only by force measuring devices located on the lifting devices. Furthermore, in order to carry out correct weighing, it is necessary to remove the sealing devices which contact the press container from the press container. After this determination of the tare weight of the press container, the lifting devices are retracted, the press container stands on the base plate, and the sealing devices ensure a seal between the transportable press container and the upper part of the press. It is then started in the usual way with the filling and pressing of the fiber flake, the fiber flake accumulated in a filling shaft being discharged in batches with the aid of a rake stripper becomes. In the usual way, after a predetermined number of clearing movements, the press ram is set in motion for the first time and the fiber material already present in the press container is pre-pressed. After the press ram has been raised again, the press container is filled again by a predetermined number of clearing movements of the reamer, followed by a pre-pressing with the help of the press ram. This type of filling and pre-compression of fiber flake within a pre-press has been known for a long time. It is decisive according to the method according to the invention that after a predetermined number of movements of the ram or a predetermined number of thrust-like movements of the reamer, the filling of the transportable press container is briefly interrupted and, as in the determination of the tare weight with the aid of the lifting devices and the force measuring devices attached to it Weight of the now partially filled container is determined. The measured values obtained are evaluated in a measuring center. In addition to the actual weight of the material deposited, the average weight of a clearing thrust is calculated and at the same time the number of clearing movements that are still necessary until a target weight is reached. The pre-press is then moved on in the usual way, that is to say the fiber scraper is used to provide additional fiber flake, which is then compressed using the press ram.

After reaching the pre-calculated number of broaching movements, the further filling process is interrupted and the filled press container is removed and replaced by a new one.

The method according to the invention can be further refined by weighing the press container again shortly before the predicted target number of clearing movements is reached, and so an even more precise determination of the average weight per clearing movement and also the number of thrusts of the clearing device still required can be determined . In this way, the target weight can be maintained with considerable accuracy. The range of fluctuation of the bale weights is then about half of the average weight of a clearing movement, i.e. z. B. at about ± 2 kg.

If this accuracy is not sufficient in the individual case, a further dosing device for fiber flakes can be provided, which, for example, works like the clearing device but with a smaller amount.

Smaller quantities of fibers can also be added by intervening in the guide geometry of the broaching device used. Such an intervention in the geometry is e.g. B. given when a guide lever is replaced by a variable guide system or the distance of the tines from their axis of rotation is reduced in commercially available scrapers.

The device required according to the invention consists of a pre-press as described, for example, in German Offenlegungsschrift No. 29 11 958. In particular, it has a transportable press container that can be inserted into the pre-press. The supply of the fiber flake takes place in the usual way via a filling shaft which opens approximately horizontally at its lower end into the upper part of the pre-press. At this mouth there is a scraper, which has a plurality of tines, each of which moves a push of fiber flake into the upper part of the pre-press in a kind of gripping movement.

According to the invention, it is necessary for this pre-press to have special lifting devices for the transportable press container, which are capable of lifting the press container so that it is no longer in contact with other parts of the device. Force measuring devices are attached to the lifting devices, which can determine the weight of the container including its contents.

In order to carry out a correct measurement, it is necessary that the sealing devices between the upper part of the press and the movable press container, which are necessary during the filling process, have been removed. This is possible with appropriate movement devices, the sealing devices naturally also having to be movably mounted.

To operate such a pre-press with a weighing device, it is necessary that the measured values are processed in a control center, i.e. that the tare weight is registered there when the empty press container is weighed and then the filling weight after about 2/3 filling. The number of strokes of the clearing device must also be recorded and the average weight per clearing movement and the number of clearing movements still required must be calculated from the measured fill weight and the number of clearing movements. Such control and computing systems are known in principle, a detailed explanation is therefore not necessary at this point. If necessary, a second metering device for small amounts of fiber flake should be provided, which in the final phase of the filling can then optionally add 1 or 2 kg to the amount of fiber already in the pre-press.

Another possibility for dosing reduced quantities per broach by interfering with the guide geometry of the broaching device will be described below.

• Figur 1 zeigt dabei eine Vorpresse im Querschnitt mit angedeuteter Hebevorrichtung während
• Figur 2 ebenfalls im Querschnitt einen Ausschnitt aus der Figur 1 im Detail wiedergibt.

The attached figures describing exemplary embodiments are intended to serve to further clarify the invention.

• Figure 1 shows a pre-press in cross section with indicated lifting device during
• Figure 2 also shows in cross section a detail from Figure 1 in detail.

FIGS. 3 and 4 show in cross section embodiments of broaching devices with changeable guide geometry,

FIG. 5 shows a top view rotated by 90 ° of the details of a clearing device shown in FIG. 4.

The fiber flake to be packaged is fed into the filling shaft 1 by conveying devices, in which it accumulates, but does not move beyond the horizontal branch, in particular when the clearing device 2 is in a corresponding position.

The clearing device 2 consists of an arm 3 which is moved about axis 4 and carries an axis 6 with a plurality of prongs 7 at the pivot point 5. The position of the tines 7 when the arm 3 rotates about the axis 4 is predetermined by a lever system 8, 9, the pivot point 10 being fixed to the housing, in contrast to the axis 11, which is freely movable. When the arm 3 is rotated, the tines 7, due to their coupling to the lever system 8, 9, perform a gripper-like movement which engages in the horizontal part of the filling chute 1, the tines 7 through cutouts 12 in the filling chute 1 and cutouts 13 in the The upper part of the press work. The actual press consists of the upper part 14 with press ram 15, which can be moved up and down via a piston rod 16.

In the lower part of the press, the transportable press container 17 can be seen, which was lifted from the base 19 by means of lifting and force measuring devices 18, 18 '. Furthermore, a roller 20 of a roller conveyor path has been indicated. The empty transport containers are normally delivered on this roller transport path and the filled press containers are removed. The base 19 usually also has centering devices which ensure precise positioning of the press container relative to the pre-press, in particular to the press ram 15. Such centering devices have not been shown here since they are not the subject of the invention. The base plate 19 is usually extendable. It is thus possible to reduce the gap between the press container 17 and the upper part of the press 14 and, at the same time, to relieve the roller conveyor path of the press forces of the press ram 15.

The special situation at the upper edge of the container 17 in the vicinity of the lifting and force measuring device 18 is shown again in detail in FIG. From this it can be seen that the lifting and force measuring device is movably attached to a frame support 21 on this side of the pre-press, namely once via bearing 22, axis 23, lever 24, and rod 25, and on the other hand via bearing bolts 26, 27, an adjusting device 28 and a support bracket 29. The actual load cell 30 is mounted on the rod 25.

When the adjusting device 28 is extended, the rod 25 and thus the force measuring device 30 or the measuring devices are pivoted out and moved under the edge of the transportable press container 17 and the press container 17 is thus raised. To protect the measuring device, suitable locks must be used to ensure that during the measuring process, i.e. during use of the lifting and force measuring device 18, the press ram 15 must not be used.

FIG. 2 also shows a sealing device which consists of a frame-shaped structure 31 which is delimited by a circumferential soft seal 32. This sealing frame 31 with seal 32 is carried over a plurality of lever and rod systems 33, 34 and supports 35, 36.

In this embodiment, a stop 37 serves to limit the path of the seal downward. A special plunger system 38, 39 is connected to the lever 34.

This plunger scans the position of the lever 24. When the lifting and force measuring system 18 is extended, the plunger 38, 39 and thus the lever system 34, 33 are raised, with the result that the frame system 31 with the seal 32 is raised so far that the seal 32 and of course also the frame 31 no longer touches the press container 17 even in its raised state.

As already explained above, a special representation of the measuring and control systems was omitted in detail. It should also be noted that, of course, measuring devices must be available which register the number of revolutions or lifting movements of the clearing device 2. Furthermore, it is expedient to monitor the degree of filling of the filling shaft 1 with the aid of light barriers or the like. It is thus possible, in a preferred embodiment of the method, to leave the press ram 15 on the material to be pressed in the container 17 until sufficient material has again been collected in the filling shaft by a conveyor device, not shown, i.e. that the next predetermined number of clearing movements can be carried out without shortages.

It should also be pointed out that usually the press container 17 must still have spring-mounted retaining flaps in order to prevent the pre-pressed material from swelling back. Retaining flaps or fingers of this type are known, and the figures have therefore not been shown.

As already mentioned above, the Dosing of smaller amounts of fibers than with a push of the broaching device is also possible by intervening in the guide geometry of the broaching device used.

Such an intervention can take place, for example, by replacing the lever arm 9 in FIG. 1 with a guide system 40 with a movement device 49. Such an embodiment is shown in Figure 3.

According to this embodiment, the guide system 40 consists of four levers 42, 43, 44, and 45, which are movably connected to one another via the bearings 46, 47 and 48 and via the pivot point 10 and a movement device 49.

According to the embodiment shown in FIG. 3, the guide system 40 is movably connected to a movement device 49 via the axis 48 and is in turn movably attached to a holding arm 50 which can be moved about the pivot point 10.

If the movement device 49 ensures that the axis 48 is fixed in its position relative to the pivot point 10, this means that the levers 42, 43, 44 and 45 cannot change their position relative to one another and thus the axis 11 a constant distance from the fulcrum 10 must have. When the arm 3 rotates and thus the tines 7, which are movably mounted at the fulcrum 5, and the lever arm 8, the axis 11 describes a reciprocating movement on a circular arc 51. The tip of the tines 7 thereby executes a movement through the path 52 of Figure 3 was indicated. The associated end points of the movement of the axis 11 on the circular path 51 were identified with 11 'and 11 "in FIG. 1.

A change in the movement device 49 inevitably leads to a change in the distance of the axis 11 from the pivot point 10. When the distance of the axis 11 from the pivot point 10 is shortened, the axis 11 must move in a circular path around the pivot point 10, which has a smaller radius than the original path 51. As a result, the tines 7 can no longer penetrate as far as was indicated by the curve 52 when they are inserted into the filling of the filling shaft 1. However, this means that a smaller amount of fiber flake is transported per broaching movement.

In FIG. 3, an extremely short setting of the guide system 40 is shown in dash-dotted lines. Such a position of the levers 42, 43, 44, 45 and thus the displacement of the axis 11 on a circular path 53 is not preferable for continuous operation. Such a strong change in the radius of the circular arc on which the axis 11 is guided is rather only suitable for significantly reducing the delivery rate in a single stroke. For the operation of the device under these conditions, it is necessary that after reaching the end point 11 'of the axis 11 and by actuating the movement device 49, the axis 11 is first moved on a path 54 until the desired new position of the axis, which is 55 was marked. As the tines move further on the circular path 41, the axis 11 moves on the small circular arc 53. It is then necessary for the movement device to guide the guide system back again. This can happen, for example, when the end point 56 is reached, with the result that the axis 11 leaves the path 53 and is fed to the lower end point 11 "on a curved path 57. The tips of the tines 7 perform a movement under these conditions, which was characterized by curve 58. When comparing curves 52 and 58, it becomes clear that when the tine tips are guided according to curve 58, a significantly smaller amount is naturally associated with each broaching movement, ie per revolution of arm 3.

In addition, it should also be pointed out that the stabilizing effect of the lever system 42, 43, 44, 45 can be dispensed with if the movement device 49 can be held in defined positions. Under these circumstances, the piston rod of the movement device 49 can be connected directly to the lever arm 8 via the axis 11.

Another possibility of intervention in the geometry of the broaching device influencing the thrust is shown in FIGS. 4 and 5. FIG. 4 again shows a cross section through parts of the clearing device as in FIG. 3. As can be seen, however, the axis 6, which carries the tines 7, was mounted in an elongated hole 59 in the arm 3. Depending on the distance at which the axis 6 rotates about the axis 4, there are inevitably also different paths for the tips of the tines 7.

In a driving style in which only the delivery rate of the last thrust has to be reduced, it makes sense that the distance between the axis 6 and the axis 4 is reduced only when the last rotary movement of the arm 3 is required. The rotation of axis 6 then follows path 41 ', for example.

The control of the position of the axis 6 to the axis 4 can take place according to FIG. 3 in that the axis 4 is designed as a hollow axis in which a non-rotating rod 60 was mounted so as to be displaceable in the direction of the axis 4. The rod 60 carries at one end a bearing 61 with a movably attached connecting rod 62. This connecting rod 62 is in turn connected to a bearing 63 for guiding the axis 6 in the elongated hole 59. When the connecting rod 62 is parallel to the arm 3, the axis 6 is in its most distant position to the axis 4 when the rod 60 is extended, the rod 62 can only be at an angle to the arm 3, the distance between the axes 4 and 6 being thereby noticeably shortened.

With such devices, various method variants can be carried out according to the invention. On the one hand, it is possible, after a predetermined number of clearing movements, as described in the master application, to determine the weight and the average weight of fiber flakes per clearing movement. Then the minimum number of thrusts of the broaching device can be calculated, in which the average weight of fiber flake per broaching movement is reduced by changing the geometry of the broaching device to such an extent that the specified target weight is achieved with a whole number of thrusts.

If, for example, the weight in the press container and the average weight of fiber flake per broaching movement are determined after about half of the expected broaching movements, a very small reduction in the distance between the axis 11 and the fulcrum 10 by the desired reduction in the conveying capacity is sufficient, for example subsequent large number of clearing movements.

A prerequisite for the functionality of this method, however, is that the flake in the chute 1 is piled up very evenly and only slight fluctuations in the delivery rate per clearing movement occur.

A procedure that is relatively unaffected by storage fluctuations is that, as described above, after a certain number of clearing movements with a maximum stroke, the weight and the average weight of fiber flake per clearing movement and the number of clearing movements still required are determined. However, the transportable press container with contents is weighed again shortly before the desired number of clearing movements with maximum stroke is reached. The repeated weighing and calculation of the average conveying capacity per clearing movement results in a possibly corrected number of the clearing movements still required with a maximum stroke and a decision as to whether an additional clearing movement with a greatly reduced stroke is then necessary to achieve the target weight. In this method, the maximum stroke is reached up to the penultimate clearing movement, a check weighing then shows whether the target weight has already been reached within given limits or whether an additional clearing movement of the clearing device with a possibly greatly reduced stroke is necessary. In such a case, according to the exemplary embodiment in FIG. 3, the movement device 49 would have to be actuated at the moment in which the axis 11 had reached its top dead center at 11 '. The axis 11 and thus the lever arm 8 would then be guided along the curve 54 to the new top dead center 55, from which the axis 11 would follow the circular path 53. With this sharp reduction in the distance between the axis 11 and the fulcrum 10, it is necessary to ensure that a timely return of the axis 11 z. B. according to curve 57 to bottom dead center 11 ", since with such a large reduction in the radius from circular arc 51 to circular arc 53, a break in the machine could occur without the installation of a compliant element. A simple way of solving this The problem is either to install corresponding resilient safety elements or to operate the movement device 49 pneumatically and to control it only on one side.

Claims (11)

1. A process for packing staple fibers into bale form by multistage pressing which involves introducing the staple fibers by means of a clearing device in pushsized batches into a transportable press container and precompacting each time the amount of fiber from several pushes by the clearing device by means of a pressing ram and then subjecting the filled transportable press container to a final pressing in a central press, characterized in that first of all subjecting the empty press container to a weighing in which the press container is freed from touching sealing devices, is lifted by lifting devices and is weighed by load-measuring devices mounted thereon, and the press container is then put down again, the sealing devices are closed and the lifting devices are pivoted out, then starting with the usual filling and precompacting, the number of clearing motions being monitored, determining the weight and the average weight of staple fibers per a clearing motion after a predetermined number of clearing motions, and therefrom calculating the number of clearing motions or pushes still required for reaching the target weight, and then carrying out these motions or pushes in conventional manner.

2. The process as claimed in claim 1, characterized in that the transportable press container with contents is weighed once more shortly before reaching the target number of clearing pushes and then, if necessary, the number of clearing motions still to be performed is corrected.

3. The process as claimed in claim 1 or 2, characterized in that there is present, in addition to the clearing device, a small metering device with which smaller amounts of staple fibers per metering unit can be added than with a full clearing stroke.

4. The process as claimed in claim 1 or 2, characterized in that the amount of loose fiber transported per clearing motion can be regulated by adjusting the clearing device geometry affecting the push.

5. The process as claimed in claim 1 and 4, characterized in that after a predetermined number of clearing motions with maximum push and determination of the weight of staple fibers in the press container and of the average weight of staple fibers per clearing motion, the size of push by the clearing device is reduced to such an extent that the target weight is reached exactly with a minimum integral number of further clearing motions.

6. The process as claimed in claim 2 and 4, characterized in that shortly before reaching the target number of clearing motions with maximum push, a further weighing is carried out and the number of clearing motions with maximum push still to be carried out and, if necessary, a single additional clearing motion with reduced push are fixed and performed in order to reach the required target weight.

7. A press for depositing and prepressing staple fibers in a transportable press container where the staple fibers are accumulated in a chute and then introduced by a clearer in pushsized batches into the press container, characterized in that the press having lifting devices (18, 18") for the transportable press container (17) which are able to lift the press container (17) from its base (19), load-measuring devices (30) which are fixed on the lifting devices (18, 18') in such a way that on using the lifting devices; they support the press container (17), movable seals (32) between the upper part of the press (14) and the press container (17) which are removable from the press container (17) by movement devices (33-39) as well as control devices which, in addition to controlling the customary machine motions, can also determine the tare weight of the empty container, the filling weight after a predetermined number of clearing pushes, the average weight per clearing push as well as the number of clearing pushes still required for reaching a predetermined target value.

8. The press as claimed in claim 7, characterized in that there is present, in addition to the clearer, a further metering device which can add smaller unit weights of loose fiber than the clearer with one stroke.

9. The press as claimed in claim 7, characterized in that the spatial position of the teeth (7) of the clearing device (2), in their circular motion about the axle (4), is determined by a lever arm (8) firmly connected to the teeth (7) and by a guide system (40), the guide system (40) being connected to the lever arm (8) via an axle (11) and being rotatably mounted on the fixed turning point (10), and the guide system (40), in cooperation with a movement device (49), adjustably fixes the distance of the axle (11) from the turning point (10).

10. The press as claimed in claim 9, characterized in that the guide system (40) comprises 4 levers (42,43,44,45) which are movable connected, via turning axles (46, 47, 48) and a turning point (10), so as to form a rectangle.

11. The press as claimed in claim 7, characterized in that the axle (6), supporting the teeth (7), of the clearing device is movable mounted relative to the axle (4).

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