WO2000034557A1

WO2000034557A1 - Mixing fibrous constituents

Info

Publication number: WO2000034557A1
Application number: PCT/DE1999/003909
Authority: WO
Inventors: Franz Höck; Peter Engelhardt; Erich Scholz
Original assignee: Temafa Textilmaschinenfabrik Meissner, Morgner & Co. Gmbh; Scholz, Rita; Scholz, Olaf
Priority date: 1998-12-09
Filing date: 1999-12-07
Publication date: 2000-06-15
Also published as: EP1149196B1; ES2204185T3; ATE244782T1; CZ20012004A3; DE19856447A1; EP1149196B2; CZ298194B6; ES2204185T5; DE59906277D1; EP1149196A1

Abstract

The invention relates to a method and a device for mixing fibrous constituents using weight feeding according to which the fibrous material to be dosed is removed, each time, from fibrous balls and is delivered into a weighing container via a device provided for supplying material. A prefilling chamber is connected upstream from said weighing container. The weighing container is separated from the prefilling container by a controllable flap and, after weighing, the material is discharged from the weighing container and released onto a mixing strip. A desired specified weight curve is given to the weighing device for each fibrous component (I, II, III). In order to fill the weighing container (10), the device for supplying the material is controlled according to said specified weight curve by a corresponding variation of the delivery rate. The course of the weighing cycle is fixed by the corresponding percentile delivery rate over the percentile time of the weighing cycle (unit curve). The capacity of the prefilling chamber (8) corresponds to the capacity of the weighing container (10).

Description

Mixing fiber components

The invention relates to a method and an apparatus for mixing fiber components by means of weighing box feed, which is equipped with a weighing container and a prefilling space, the weighing container being separated from the upstream prefilling space by a controllable flap, and after weighing, the material from the weighing container onto Mixing belt is dropped.

For the mixing of fiber components, weighing box feeders are used for dosing the individual fiber components, in which fiber bales are fed via a feed table and a subsequent conveyor belt to a rising needle belt, from which the needle belt loosens fiber material in pies and conveys it upwards against a stripping roller. A subsequent knock-off roller feeds the material loosened in this way to a weighing container.

The weighing of the fibers according to this known discontinuous method is usually carried out in such a way that the weighing container is loaded with two different material feed speeds, the feed performance being determined by the needle belt speed. First, a rough dosing is carried out at high needle belt speed in order to fill the weighing container in the shortest possible time. However, the desired weighing weight can only be achieved inexactly with this high needle belt speed. That is why this rapid filling is only carried out to a certain degree. As soon as this first limit value of the coarse filling is reached, the needle band is switched to low speed, and it

SPARE BLADE (RULE 26) the fine dosing follows at this low speed until the desired final weight is reached. When this second limit is reached, the needle band is stopped. The exact weight is then determined by the scale. For exact weight determination, it is necessary that the scale is at a standstill, ie that it no longer carries out vibrations caused by the filling. This process can take up to 2 or 3 seconds. The weighing container is then emptied onto a so-called mixing belt and tared, ie the weighing device is set exactly to the zero point. The weighing device is thus prepared for the next weighing, and the needle belt is switched on again in order first to carry out the rough filling for the next weighing process at high speed.

Despite precise adjustment of the weighing device and immediate stopping of the needle belt, fibers still fall into the weighing container after the second limit value has been reached, so that the desired weighing value is exceeded, sometimes even fallen short of. This is particularly the case when the fiber material is only slightly opened. To compensate for this inaccuracy, this weight value is determined and weighted in the further weighing. In addition, flaps are provided above the weighing container, which close immediately when the final weight is reached in order to avoid refilling fiber material into the weighing container.

In order to accelerate the weighing cycle, it is desirable to fill the weighing container quickly, although a high needle belt speed leads to a high throughput, however, due to the poorer opening of the fiber material, the weighing accuracy is low since material and the like are entrained. A low needle belt speed leads to a better opening and thus a high weighing accuracy, but the throughput and thus the filling speed of the weighing container is low. It is half the goal of achieving the highest possible throughput during filling and still good opening and high accuracy in weighing.

The material-specific properties also play an important role in the weighing of fibers. All speeds and limit values must therefore be set to these material-specific properties. The loading of the filling space in front of the needle belt also has an influence on the parameters to be set.

Fiber mixing plants are usually operated with several weighing containers and with different raw materials. The slowest weighing determines the throughput of the entire production plant. In order to achieve the desired accuracies and throughputs in the weighing process described, it is necessary that the system is set up by operating personnel with good process knowledge and experience. The setting values have to be determined empirically for each fiber type, which is complex.

Although electronically controlled weighing devices are already known which considerably simplify the operation and monitoring of such mixing plants, it is nevertheless necessary to enter and save the corresponding data and empirical values for each component to be mixed in the control device and for the materials and in each case to be processed desired mixtures for the control program. This is time consuming and requires experienced professionals. There is also always the risk of incorrect settings. With new mixtures and materials, the empirical values must first be tried out and determined.

From DE 34 12 920 a device for dosing filling material for filling packs is known. The weighing container is filled in two stages with a coarse and a fine dosage. For the coarse dosing, the filling material is fed via a first feed line into a prechamber, which is provided with a shut-off device to the weighing container, a volumetric dimension of the filling material being provided in the prechamber. When the specified volume is reached, the pre-chamber is filled and its contents are emptied into the weighing container. After the shut-off passage between the pre-chamber and the weighing container has been closed, the fine metering takes place via a second conveyor line. During this time, the pre-chamber can already be refilled via the first conveyor section, so that the filling speed for the weighing container is reduced. A disadvantage of this known device is that two separate filling sections are required for the fine filling and for the pre-filling, so that a corresponding flap control and a corresponding feed device are required for each filling section. The device is therefore relatively complex.

A method for continuously measuring the bulk density of granular, fibrous or sheet-like material, in particular tobacco, is also known, in which the material is delivered in a steady stream by means of a first conveying means to a second conveying means and is subsequently processed in a mass-constant flow of material is supplied (DE 28 41 494). The conveying speed of the first conveying means is controlled as a function of the mass of the goods delivered to the second conveying means. The problem of nonetheless achieving continuous material conveyance and opening of the same with discontinuous weighing for mixing fiber components does not exist with this known device. The known method and the device provided for its implementation are also not suitable for assembling different fiber components according to predetermined weight fractions for further processing. Finally, an electronic control program is known from US Pat. No. 4,766,966 in order to fill a weighing container via a prefilling space in the shortest possible time, but avoiding excess weight caused by the rapid filling. The supply of the material to be weighed into the weighing container is therefore controlled by a different opening width of the outlet flaps from the prefilling container. Nothing can be gathered from the known device about the mixing of fiber components and the material feed into the prefilling space. By controlling the discharge flap opening, there is a risk with fibrous material that it gets caught on the flaps which are not fully opened and thus leads to irregularities and incomplete filling of the weighing container.

The object of the present invention is to remedy the shortcomings indicated and to create a method and a weighing device in order to considerably simplify the setting and dosing of the individual components. Another object of the invention is to achieve high production output and still achieve good opening and great weighing accuracy. These tasks are solved by the features of claims 1, 15 and 17 in combination as well as individually. Further details of the invention are described in more detail with reference to the drawings. Show it

Figure 1 shows a weighing feeder in a schematic representation

Figure 2 shows a mixing plant with three weighing feeders

the figures different curves, according to which the 3, 4 and 5 position or control of the system takes place

6 shows a comparison of the delivery rate with and without interruption of the delivery FIG. 7 a weighing feeder with an enlarged prefilling space.

Figure 1 shows a weighing feeder schematically in its structure. The bales 1 ', l ^{1 1} , l ¹ ' ¹ are fed via the feed table 2 and its conveyor belt 3 to the needle belt 4, which releases patties from the supplied bales and conveys them upwards against the stripping roller 5. The stripping roller 5 is adjustably mounted in its distance from the needle belt 4 and rotates in the opposite direction to the conveying direction of the needle belt 4. Too large amounts of fiber that rise with the needle belt 4 are not let through by this distance of the stripping roller 5, but are held back by it. As a rule, the conveyor belt 3 of the feed table 2 and the needle belt 4 are connected to one another in terms of drive. An infinitely variable drive 41 is provided for the needle belt 4, so that the needle belt can run at any conveying speed predetermined by a control device 41. The tapping roller 6, which revolves at high speed, adjoins the needle belt 4 and knocks the fiber material out of the needle belt 4 and thereby opens it. The fibers or fiber flakes released by the knock-off roller 6 are conveyed into a pre-filling space 8, which can be closed by flaps 9 and locked against the weighing container 10. A fan 7 provides for dust extraction. A mixing belt 12 is guided under the weighing container 10, onto which the fibers weighed in the weighing container 10 are thrown off. At the end of the mixing belt 12, a pressure roller 11 is arranged in order to compress the fiber material into a uniform cotton wool for feeding into a mixing opener 13.

FIG. 7 shows a weighing feeder with an enlarged pre-filling space 80. Parts of this weighing feeder with the same function are also designated in the same way as in FIG. 1, so that the description of the weighing feeder according to FIG. 1 also applies to FIG. A large prefilling space 80 is arranged above the weighing container 10, which has up to about 80% of the capacity of the weighing container 10. This enlarged prefilling space serves to accommodate the material supplied to the conveyor belt 12 during the settling time of the balance and the throwing of the contents of the weighing container 10, so that the needle belt 4 can convey fiber material without standstill. Measuring devices 13 are arranged on both sides to monitor the filling level of the prefilling space. These measuring devices preferably consist of light barriers.

FIG. 2 shows a system with three weighing box feeders I, II and III, which each drop a component onto the mixing belt 12. The dropping out of the weighing containers 10 takes place in such a way that the parts to be mixed are layered one on top of the other and at the same time enter the mixing opener 13. That first, the weighing feeder III throws its component portion onto the mixing belt 12, which transports this layer to the weighing feeder II. There, the next component is placed on the position of the weighing feeder III from the weighing container 10 and both are transported further to the weighing feeder I, which then applies the third component to the two layers. All three layers run at the end of the conveyor belt 12 under a pressure roller 11 and are fed to the mixer opener 13, which continuously mixes the layer packages and delivers them through the pipeline 14 to a mixing chamber.

The loading of the weighing container 10 takes place in a known device in such a way that in a first phase the material transport runs quickly without weight control, ie the shut-off flaps 9 are closed and the material collects in the prefilling space 8. During this time the bottom flap of the Weighing container 10 after throwing off the last weighing, and there is a balance when the bottom flap is closed. In a second phase, the material transport is still running quickly and without weight control. le, but the butterfly valve 9 opens and throws the accumulated material into the weighing container 10, the bottom flap of which is closed. In a third phase, when the material is being transported quickly, the weighing container 10 is filled until a signal is triggered at a certain filling quantity that is less than the target weight, which switches the material transport to a low speed at which the remaining filling takes place to the final weight . When the final weight is reached, the material transport is switched off and the butterfly valves 9 are closed. There is a calming time of about 2 seconds for the final weight measurement. Finally, with the material transport still switched off and the flaps 9 closed, the bottom flap is opened and the weighing is thrown onto the mixing belt 12.

The pre-filling serves to increase the production output by reducing the downtimes of the material transport, since with the shut-off valve 9 closed, the material transport can start again in the first two phases. However, the pre-filling function cannot be used according to the known method if the material transport speed is subject to strong fluctuations.

These disadvantages are eliminated by the method according to the invention. The material is fed at different speeds, but it is always in operation so that there are no downtimes. This has the great advantage that by distributing the material supply over a longer period of time, which was otherwise occupied by the downtimes, it is possible to work with lower material transport speeds, which lead to a much better opening and more precise metering. As a further object of the invention, there is no need to set the individual parameters, since the individual speeds for material transport and filling, including the time intervals within the weighing cycle, optimize themselves and thereby adjust to different materials at the same time. The procedure according to the invention is as follows:

First, the desired course of a weighing cycle is recorded in a so-called unit curve. This cycle has arisen from the sum of many empirical values and also represents the material supply as a percentage over the time of a weighing cycle, which is divided into time segments. Since the needle conveyor speed of the weigh feeder is approximately proportional to the material flow rate, this unit curve represents the percentage of the course of the needle belt speed and thus the material feed or flow rate per unit of time. It was surprisingly found that the optimal flow of the material feed speed was found in all Cases behaves approximately the same, so that this curve can be easily transferred to all concrete values in the percentage representation. This has the great advantage that the control device 40 is entered with the unit curve, the sequence of the weighing cycle and thus an essential parameter, so that for the specific individual case only the weighing time and the final target weight to be maintained have to be entered. Of course, a computer integrated in the control device 40 can also determine these two values directly from the desired production output. Since the filling capacity of the weighing container 10 is predetermined, the computer calculates the necessary number of weighing cycles and their time span, as well as the target weight to be specified for each weighing cycle. Based on the specified target weight, the computer calculates the target weight curve (FIG. 4) via the unit curve (FIG. 3), according to which the filling of the weighing container 10 is controlled by a corresponding variation of the fiber delivery into the weighing container 10 via a target / actual value comparison. The needle belt speed is expediently regulated by the drive 41 such that the needle belt 4 does not come to a standstill or only in exceptional cases, so that the material conveyance extends over the entire weighing cycle. This is made possible by the largest possible pre-filling space 80 (FIG. 7), which is at least half the size, ideally about 2/3 to the same size as the weighing container 10, and is therefore able to accommodate a continuous supply of material, too during the settling phase of the scale and the throwing off of the final weight from the weighing container 10. Only the fine filling quantity does not need to be taken up by the prefilling space, since this falls directly into the weighing container 10 when the flaps 9 are open. This not only achieves a much faster filling and thus greater performance of the weigh feeder, but also achieves better fiber opening and more accurate filling due to the now lower filling speed. Of course, the saving of material downtime can also be used to shorten the duration of the weighing cycle and thereby increase performance without sacrificing the quality of the opening.

The weighing cycle is essentially divided into three phases, namely (Fig. 6) in pre-filling (zone A), main filling (zone B) and fine filling (zone C). In addition there is the downtime (zone D). With the appropriate size of the pre-filling space 8 or 80, the main filling can be dispensed with entirely, so that the weighing cycle is only subdivided into pre-filling (zone A + B + C) and fine filling (zone D). The pre-filling takes place with the flaps 9 closed in the pre-filling space 8 or 80. During this so-called pre-filling, the settling time of the balance and the final weight measurement as well as the opening and throwing off of the final weight on the mixing belt 12 including the possibly necessary taring of the balance takes place. The fine filling is always carried out after the pre-fill chamber has been emptied and with the flaps 9 open in order to bring the scale to its final weight. In this way, up to 2 or 3 seconds can be saved, which means a reduction in the conveying speed or an increase in output of 15-25% with a normal weighing cycle of 12-14 seconds. FIG. 3 shows the unit curve, specifically for a weighing cycle without material supply downtime. As can be seen from FIG. 3, the delivery rate at the beginning of the cycle is approximately 100%. This flow rate is maintained for approximately 60% of the weighing cycle time. Then the delivery rate is reduced to about 20% and for the remaining 20 to 25% of the weighing cycle time with the decrease of the delivery rate the fine dosing is carried out up to the final weight. The area under the unit curve represents the total delivery quantity that is to be reached during the weighing cycle and is to be dropped onto the mixing belt 12 as the final weight. The target weight curve is obtained by integrating this unit curve (FIG. 5). The unit curve is set for each mixing component I, II and III, where 100% is the delivery rate that is required to reach the target weight of the corresponding component during the weighing cycle time. After all three components have the same time for the weighing cycle, the required target speed curve is based on the target weight to be achieved. Component I thus has the highest target speed, here in the example at 60 m per minute, component II at 30 m per minute and component III at approximately 10 m per minute. This corresponds approximately to the mixing ratio of the components of 60: 30: 10.

The control of the mixing process via a target weight curve derived from the unit curve can, however, also be carried out in the usual weighing cycle with the material conveying stopped during the settling time and weighing. However, FIG. 6 shows in a comparison the enormous advantages of eliminating downtimes in favor of a continuous supply of material. The heavily drawn unit curve represents the weighing cycle with the usual downtime. Zone A indicates the usual prefilling time, zone B the main filling, zone C the fine dosage and finally zone D the downtime of the feed. As an example, the percentages give a normal process of the weighing cycle. It does not matter whether the weighing cycle lasts 12 seconds or 16 seconds. In the present case, the example was taken from a weighing cycle of 14.5 seconds. As can be seen from FIG. 6, the downtime is at least 25 to just under 30%. By avoiding this downtime for the supply of material with a correspondingly large prefilling space 80, the conveying speed can be reduced to approximately 60%, or a reduction in the weighing cycle by 25% can be achieved using the full conveying speed. Since the areas under the respective curves represent the target weight quantity, it becomes clear what advantage the method according to the invention offers.

The pre-filling is carried out at a material conveying speed which is coordinated in such a way that the existing pre-filling space 8 or 80 is used well and optimally loaded in the predetermined or available time. If the size of the pre-fill space 80 (FIG. 7) is approximately 60 to 80% of the weighing container 10, the essential filling takes place in this pre-fill time. After opening the flaps 9, this pre-fill quantity reaches the weighing container 10, and only a fine filling with a low conveying speed is required in order to achieve the desired final weight exactly.

The material conveyance begins with the conveying speed (Fig. 4) caused by the target weight curve (Fig. 5). A target / actual value comparison with the predetermined target weight curve determines how much still has to be filled up to the final weight. If the difference is very large, the material conveying speed can first increase again to 100% and can only be reduced to the fine conveying for the last 10 or 20%. The aim, however, is to carry out the filling with the most uniform possible conveying speed, so that the conveying speed in the following cycle is already adjusted overall for this prefilling time. As soon as the final weight is reached, the flaps 9 close and cut off a further material supply. The material transport does not switch off, however, but immediately begins to fill the pre-filling space 8 or 80 again, while the scale carries out its settling time and weighing and throws off the weighed material.

In order to optimally use the pre-filling chamber 8 or 80, it is necessary to determine the correct speed of the material feed during this pre-filling period, because this can deviate from the target speed determined from the target weight curve (FIG. 4) due to the special nature of the material. In principle, this can also be done manually and by entering empirical values. However, it is also possible for the weighing device to optimize itself here. This is done in the following way:

According to a predefined basic setting, material transport begins at a transport speed of approximately 50% in the first weighing cycle. Depending on the size of the pre-filling room 8 or 80, it is then checked after a weighing time of approx. 60% of the weighing cycle which amount of material has reached the pre-filling room 8 or 80 at the pre-set filling speed. Of course, this depends on the material, but this material dependency is automatically included in this measurement, since the actual quantity is measured as a function of the conveying speed during this pre-filling.

This control can be done in different ways. One method is, for example, that by opening the shut-off flaps 9, the pre-filled quantity filled up to that point is thrown into the weighing container 10, so that the latter can determine an intermediate weight which is passed on to the computer, which compares it with the target weight. If this actual value is below the nominal value, this means that the 50% filling speed is too slow and corresponding to the difference between actual value and setpoint must be increased. The computer specifies the correct conveying speed for the next weighing cycle so that the pre-filling space 8 or 80 is optimally used. If the pre-fill quantity is too high, the speed is reduced accordingly. This eliminates the usual adjustment measures. This process can also be repeated for refinement.

Another type of optimization of the pre-filling speed is to equip the pre-filling chamber 8 with a measuring device for the degree of filling (measuring probe, light barrier, etc.). The prefilling space 8 is filled until the transmitter responds and indicates the filling of the space, whereby the flaps 9 open. At the same time, the required time is determined and the optimal filling speed is calculated and set in the computer by increasing or decreasing the basic setting. With this method, the pre-fill quantity can then be brought to the final weight and used as the first weighing.

In order to avoid overfilling of the pre-fill chamber 8, it is advisable to start with the optimization of the conveying speed from such a low conveying speed at which the complete filling of the pre-fill chamber 8 or 80 is certainly not yet achieved. This is usually achieved with around 50% of the conveying speed. In the first weighing cycle, after approximately 25 to 70% of the weighing cycle time, the optimum starting speed of the needle belt 4 or the conveying speed is determined by comparing the actual weight with the target weight, as already described above.

Of course, it can also be provided that the once determined conveying speeds for certain materials and component compositions are stored and called up when the same case is repeated, without corresponding optimization having to take place again. In the Automatic self-optimization is generally more advantageous, however, because incorrect settings are avoided and the personnel do not have to worry about setting the correct pre-filling speed.

In the following weighing cycles, the optimal conveying speed is determined after the optimization. As soon as the pre-filling is reached, the control switches to the filling speed specified by the target weight curve. The speed along this curve is controlled by a controller which expediently acts on the delivery speed of the needle belt 4, so that a corresponding decrease in the filling speed takes place in order to carry out the fine metering when the final weight is reached. As soon as this final weight has been reached, the cycle for the material supply has already ended and the speed of the conveyor belt 4 is switched to the optimized conveying speed after the flaps 9 are closed, with which the pre-filling process and thus the new weighing cycle begins. Thus, while the pre-filling space 8 or 80 is already being filled with material again, the weighing device with the weighing container 10 remains in the settling time, and after the same has expired, the weighed material is thrown onto the mixing belt 12 by opening the weighing container 10.

Of course, even with this weighing method, the deviation of the actual weight from the target drop weight is determined at the end of the weighing cycle and taken into account in the subsequent weighing cycles. As usual, this can be done by weight, but the conveying speed can also be influenced in order to optimize the process. This is done in such a way that the course of the weighing cycle remains the same according to the standard curve, but the calculated correction speed is set equal to 100% of the delivery quantity and thus the specification of the target weight and the target speed curve derived therefrom. ve corrected itself. In this way, a very precise weighing is achieved.

As can be seen from FIG. 2, several components are usually to be put together and mixed for the mixture. A weighing feeder I, II or III is provided for each component. In this case, three components can be mixed. Since the individual proportions of the components are of different sizes, the filling of the weighing containers 10 takes different lengths in the usual known filling methods, so that the component which determines the largest proportion also takes the longest time, so that the other two weighing feeders tend to start their weighing process have ended and have to wait for the weight feeder with the largest amount to drop their weight. According to the invention, these three weighing feeders are so coordinated in their filling speed that all three weighings are finished at the same time. By determining the target weight curve from the unit curve for each component and specifying the weighing feeder concerned, the speed curve for the filling speed is reduced accordingly. The pre-filling is slower, but the filling to the final weight can also be maintained regardless of the pre-filling speed, so that the same period is filled as for the largest component. Since the specified target weight curve is derived from the unit curve, the weighing cycle takes place as a percentage in the same way as for the largest component. A special setting for this is not necessary. The unit curve is specified in each control unit or in the control unit of the overall system. It is therefore only necessary to enter the desired production output or the weighing cycle and the desired final weights for the individual components. Everything else, including the optimization of the process, is carried out by the computer of the controller. In order to always have the same mixture at the beginning as well as at the end of a mixing section, the control can also be programmed so that the discharge of the weighed fiber quantities begins and ends one after the other, so that complete mixing packages always result. In the example in FIG. 2, the weighing feeder III will drop its last weighing onto the mixing belt 12 and then already stop its work. The last discharge quantity then reaches the weighing feeder II, which throws its component onto this last weighing of the weighing feeder III and then also ceases to operate. The mixing system is only switched off when this mixing package has also passed the last weighing feeder I. The start takes place in exactly the same way by starting the weighing feeder III and switching on the weighing feeders II and I one after the other.

In the example described, the process control was described by specifying a desired target weight curve, according to which the material feed into the weighing container 10 is controlled. This target weight curve can also be determined empirically, but it is advantageous to determine this according to the invention using the unit curve.

The optimization of the conveying speed, in particular for the pre-filling, is not only important in connection with the larger pre-filling space 80, which can hold practically the entire filling quantity except for the remaining filling for fine metering. Even with the conventional, known weighing methods, the enlarged prefilling space 80 can be used successfully and can shorten the process considerably or reduce the required conveying speed.

As can be seen from FIG. 6 on the basis of the continuous, strongly drawn curve, it is also possible to specify a standard curve for the material conveying even for the conventional weighing process with standstill (area D) and then to control the cycle. Thus, these parts of the invention are of independent importance, but the optimum is achieved by using all of the parts described together. The embodiments described are only examples and can be modified in various ways or combined in another way without leading out of the inventive concept.

Claims

Patent claims

1. Method for mixing fiber components by means of weighing feed, in which the fiber material to be dosed is removed from fiber bales and conveyed from a material feed into a weighing container, which is preceded by a prefilling space, the weighing container being separated from the upstream prefilling space by a controllable flap is, and after weighing, the material is dropped from the weighing container onto a mixing belt, characterized in that for each fiber component of the weighing device (I, II, III) in question, a desired target weight curve (Fig. 5) is specified, according to which the material supply for the filling of the weighing container (10) is controlled by varying the conveying speed accordingly.

2. The method according to claim 1, characterized in that the course of the weighing cycle is determined by the respective percentage delivery over the percentage time of the weighing cycle (unit curve).

3. The method according to any one of claims 1 or 2, characterized in that the target weight curve (Fig. 5) for each component (I, II, III) is determined from the unit curve (Fig. 3), based on the target weight of the component ( I, II, III), which is to be achieved in a weighing cycle.

4. The method according to one or more of the preceding claims, characterized in that the same duration of the weighing cycle is predetermined for the individual components (I, II, III) (Fig. 5).

5. The method according to one or more of the preceding claims, characterized in that the weighing cycle in a prefilling phase, while v / elcher the conveyed material is collected in a prefilling space (8; 80), and is divided into a fine filling phase (Fig. 6) , during which the conveyed material passes through the prefilling space (8; 80) directly into the weighing container (10).

6. The method according to one or more of the preceding claims, characterized in that the variation of the material supply takes place by changing the conveying speed of the needle belt (4).

7. The method according to one or more of the preceding claims, characterized in that the adjustment of the actual weight to the target weight given by the target weight curve is carried out by a controller.

8. The method according to claim 7, characterized in that the controller influences the current conveying speed of the needle belt (4).

9. The method according to one or more of the preceding claims, characterized in that the time of the weighing cycle is determined by the mixing belt speed.

10. The method according to one or more of the preceding claims, characterized in that the dropping of the weighed fiber amounts onto the mixing belt (12) in succession begins and ends one after the other, so that complete mix packages are always created.

11. The method according to one or more of the preceding claims, characterized in that in order to determine the optimum conveying speed, the conveying speed of the material feed (4) for the first weighing cycle is set on the basis of an empirical value and, after 25 to 70% of the weighing cycle time, the actual weight achieved with the The target weight is compared and the difference determined in this way is used to correct the conveying speed of the material feed (4).

12. The method according to claim 11, characterized in that the empirical value for the optimization of the conveying speed is about 50%.

13. The method according to one or more of the preceding claims, characterized in that the conveying speed for the fine metering remains unchanged, regardless of the change in the conveying speed for the material conveying during the prefilling and / or main filling.

14. The method according to one or more of the preceding claims, characterized in that at the end of the weighing cycle, the deviation of the actual weight from the target discharge weight is determined and the difference is taken into account to correct the conveying speed.

15. A method for mixing fiber components by means of weighing feed, in which the fiber material to be dosed is removed from fiber bales and conveyed from a material feed into a weighing container, which is preceded by a prefilling space, the weighing container being separated from the upstream prefilling space by a control erable flap is separated, and after weighing the material is thrown out of the weighing container onto a mixing belt, characterized in that the material feed (4) promotes fiber material during the entire weighing cycle, while the loading of the weighing container (10) is carried out discontinuously.

16. The method according to claim 15, characterized in that the conveying speed of the material feed (4) approaches zero at the end of the fine metering, but immediately after closing the butterfly valves (9) the full conveying speed resumes (Fig. 3, 4 and 6).

17. Weighing feeder in which the fiber material to be metered is conveyed from a material feed device into a weighing container, which is preceded by a prefilling space, and the weighing container is separated from the upstream prefilling space by a controllable flap, characterized in that the material feed device (4) is a control device (40) is assigned, which controls the conveying speed of the material feed (4) in accordance with a predetermined target weight curve (FIG. 5).

18. The apparatus according to claim 17, characterized in that the material feed device has a needle band (4) that detaches fiber material from the supplied bale and is provided with a continuously variable drive (41).

19. The device according to one of claims 17 or 18, characterized in that the capacity of the prefill space (8; 80) corresponds to the capacity of the weighing container (10).

20. The device according to one or more of the preceding claims, characterized in that the capacity of the prefill space (8; 80) has about 80% of the capacity of the weighing container (10).

21. The device according to one or more of the preceding claims, characterized in that the capacity of the pre-fill chamber (8; 80) has at least the capacity of the weighing container (10) minus the fine filling amount.