WO2004018748A1

WO2004018748A1 - Method and device for drafting at least one sliver

Info

Publication number: WO2004018748A1
Application number: PCT/EP2003/006088
Authority: WO
Inventors: Joachim Dämmig
Original assignee: Rieter Ingolstadt Spinnereimaschinenbau Ag
Priority date: 2002-08-10
Filing date: 2003-06-11
Publication date: 2004-03-04
Also published as: DE10236778A1; DE10236778B4; CN1675417A; EP1529127B1; EP1529127A1; US20050278900A1; AU2003236733A1; CN1675417B

Abstract

Disclosed is a method for drafting at least one sliver (FB) by means of a regulated spinning machine, particularly a carding machine or drawing frame, comprising pairs of rollers (2a, 2b, 3a, 3b, 4a, 4b) which are disposed one behind another and upstream of which the cross section of the at least one sliver is measured. The inventive method is characterized by the fact that at least one roller (2a, 3a) of a first pair of rollers (2a, 2b, 3a, 3b) is triggered via a first regulating circuit while at least one roller (4a) of a second pair of rollers (4a, 4b) is triggered via a second regulating circuit based on the measuring signals. Also disclosed is a device for carrying out the inventive method.

Description

Method and device for drawing at least one sliver

The invention relates to a method for stretching at least one sliver by means of a regulated spinning machine, in particular a card or draw frame, which have roller pairs arranged one behind the other, the mass cross section of the at least one sliver being measured upstream of the roller pairs. Furthermore, the invention relates to a device for stretching at least one sliver with at least one upstream and one downstream pair of rollers, with at least one sliver cross-section measuring device arranged upstream of these roller pairs, for detecting the mass cross-section of the at least one sliver.

Spinning machines such as cards or draw frames serve the purpose of forming a textile material that is as uniform as possible from the textile material presented. For this purpose, the spinning machines often have a regulated drafting device, in order to control warping elements arranged one behind the other in accordance with the fluctuations determined, based on strip cross-section fluctuations measured in front of the drafting arrangement in the strip running direction. In the case of lines, these drafting elements are formed, for example, by a plurality of pairs of rollers arranged one behind the other, between which the fiber sliver or slivers are clamped along the respective so-called clamping line in the belt transverse direction. Since the pairs of rollers have different circumferential speeds that increase in the direction of belt travel, the fiber composite consisting of one or more fiber bands is stretched and evened out. In most cases, a second belt cross-section measuring device is provided at the exit of the drafting device in order to form feedback in a closed control loop or to check the equalization and, if necessary, to trigger a machine stop if the belt number fluctuates excessively.

Mechanical scanning devices have largely prevailed for scanning. For example, the Rieter draw frame RSB D30 has a pair of scanning disks with axes parallel to one another in front of the drafting system, one scanning disk arranged stationary and the other scanning disc is designed to be movable. The fiber sliver or slivers are passed in a gap between a circumferential groove of the first scanning disk and a circumferential ring of the second scanning disk, the movable scanning disk being deflected in accordance with the fluctuations in mass of the sliver or slivers. The deflection movements are converted into electrical voltage values by a signal converter and passed on to a regulating processor for controlling the roller pairs of the drafting system.

In the case of spinning machines in particular, in which the scanning gear and the roller pairs are connected to one another via, for example, a differential gear, the adjustable frequency range is relatively restricted with regard to the fluctuations in the cross-section of the strip. Due to the large inertia of such an arrangement, a desired regulation over a large frequency range from longer-wave fluctuations (so-called A% values) to regulation lengths of a few centimeters at high delivery speeds is not possible. In addition, the wear of machine parts, caused by the wide range of signal contents and the associated acceleration of large masses, and the energy consumption are relatively high.

FIG. 1 shows a regulated drafting arrangement in which a fiber sliver FB passes through a mechanical strip cross-section measuring device 8 and is then guided into a drafting arrangement formed by three pairs of drafting unit rollers 2a, 2b, 3a, 3b, 4a, 4b. The belt cross-section measuring device 8 is formed by two scanning disks, which have already been described above.

One of the two scanning disks is coupled to a clock generator 11, which generates a certain number of clocks or pulses per revolution of this scanning disk. Furthermore, the movable scanning disk is connected to a signal converter 10, which converts its deflection movements into electrical voltage values. These voltage values are then passed on to a measured value delay unit 12, which also receives a number of clocks from the clock generator 11, which are a measure of the speed of the sliver FB running through the sliver cross-section measuring device 8. In accordance with these clocks from the clock generator 11, the voltage values in the measured value delay unit 12, which represents an electronic memory in the form of a FIFO (First-In-First-Out), are covered in accordance with the ten way between the belt cross-section measuring device 8 and the drafting system. When the sliver with the piece of tape to be regulated reaches the fictitious point of warpage in the draft zone of the drafting system, the corresponding measured value is released by the measured value delay unit 12 and a corresponding steep action is carried out depending on the respective measured value. The distance between the measuring location of the pair of scanning rollers and the location of the delay is called the control starting point. For this purpose, the measured value delay unit 12 forwards the measured values to an algorithm unit 13, which calculates the rotational speed of the drawing frame rollers concerned on the basis of the desired draft setting and the set machine parameters and forwards the corresponding information to a control drive 22. This control drive 22 drives in a differential gear 23, which drives the stationary scanning disk of the belt cross-section measuring device 8, the lower roller 2a of the input roller pair and the lower roller 3a of the central roller pair. The differential gear 23 receives a basic speed from a main motor 14, which can be set via a speed setting unit 15 interposed between the main motor 14 and the differential gear 23.

The main motor 14, in turn, directly drives the lower roller 4a of the pair of output rollers, thereby maintaining a constant tape exit speed. Accordingly, only the input roller pair and the middle roller pair are used for the regulation.

It is an object of the present invention to develop the method and the device of the type mentioned in the introduction in such a way that a more precise warping of one or more fiber slivers is obtained.

This object is achieved in the method of the type mentioned at the outset in that, based on the measurement signals, at least one roller of a first pair of rollers is controlled via a first regulating circuit and at least one roller of a second pair of rollers is controlled via a second regulating circuit.

This object is also achieved in a device of the type mentioned at the beginning by at least two regulating circuits, with at least one roller of a first pair of rollers and via the second regulating circuit, at least one roller of a second pair of rollers can be controlled.

The advantages of the invention can be seen in particular in the fact that the scanning signals are processed in front of the drafting system in at least two regulating circuits in order to increase the flexibility and the accuracy in the control of the drafting elements or rollers. The at least two regulating circuits can react to different signal contents and thus take over a distribution of the control tasks. In this way, at least one roller of a first pair of rollers and at least one roller of a second pair of rollers, which are at least partially decoupled with respect to their inertia control, can be driven.

The frequency of the measurement signal components of the at least one band cross-section measuring device is particularly preferably divided into at least two frequency ranges. The rollers of different roller pairs can then be controlled on the basis of the affiliation of measurement signal components to different frequency ranges. In this way, regulation in the frequency domain is shared. Each frequency band can thus be distributed to adapted machine elements according to its energy requirements.

It is advisable to use low-frequency measurement signal components, i.e. longer-wave band cross-section fluctuations, to control machine elements or drive elements with a higher moment of inertia. Correspondingly, higher-frequency measurement signal components can be used to control drive elements with a low moment of inertia. Due to the low mass inertia, these machine elements can be accelerated or braked more quickly, so that these machine elements can also follow the higher-frequency measurement signal components. Overall, a more precise regulation is obtained, whereby both longer-wave and shorter-wave band cross-section fluctuations can be optimally regulated.

Defined signal processing benefits if the measurement signal components of the strip cross-section measuring device upstream of the drafting device are allocated to at least one lower and one upper frequency range. In order to To be able to use the frequency components of the band cross-section fluctuations, the lower and the upper frequency range are preferably close to one another, particularly preferably essentially without gaps, or overlap.

The upper frequency range is preferably selected in such a way that machine elements with a higher moment of inertia can be processed essentially without loss. Likewise, the lower frequency range is preferably selected in such a way that machine elements with a lower mass moment of inertia can be processed essentially without loss.

It has proven to be advantageous if the lower frequency range comprises frequencies in the range of approximately 0-3 Hz and the upper frequency range frequencies in the range of approximately 3-100 Hz. However, these frequency ranges are not to be regarded as fixed, but can advantageously be selected or set depending on the regulating path and / or material to be warped or other parameters. The named maximum frequency of 100 Hz is also not a technical variable. Depending on the design of the drafting system or the masses to be accelerated, lower or higher limit values are also possible.

There are various possibilities for assigning different measurement signal components to different frequency ranges. In preferred exemplary embodiments, frequency filters implemented in hardware and / or software are used for this.

Preferably, one roller of the pair of input rollers and of the middle roller pair is actuated in the first regulating circuit, while one roller of the pair of supply rollers is actuated in the second regulating circuit. Contrary to the prior art described above, the pair of delivery rollers is therefore also used for regulation. Due to its low mass inertia, it is possible to regulate higher-frequency strip cross-section fluctuations by controlling the pair of delivery rollers. Since this outlet regulation produces no additional delay on average, the known disadvantages of outlet regulations, which consist in particular in the fact that the sliver deposition speed varies and thus problems with these known machines with regard to a clean deposition of the warped sliver in a spinning can, are eliminated. In contrast, the described preferred variant of the invention in principle forms an inlet regulation with superimposed outlet regulation. The The basic delay and the compensation of low-frequency band fluctuations of up to 3 Hz, for example, are carried out with the help of the low-frequency regulation, which in principle corresponds to the known regulation, for example on the Rieter range RSB D30. The higher frequency band is then modulated onto this delay by the higher-frequency regulation in the drafting system. This higher-frequency regulation corresponds to precise CV% regulation, the CV% value being defined as CV% = s / x * 100. Here ^~ CV% is the coefficient of variation (percentage band unevenness), s the standard deviation and x the mean value of all Rehearse.

The above-described, particularly preferred embodiment of the invention is therefore distinguished by the superimposed regulation via the pair of outlet drafting or delivery rollers.

The control in the first and second regulating circuits is preferably carried out in such a way that the control starting point or delay point in the warping zone formed by the pair of central rollers and the pair of delivery rollers is identical for both regulating circuits. This means that the delay point is identical for both control loops and there is no measurement delay between the two control loops - with the help of a FIFO memory or the like. - is needed. In other words, the different frequency ranges are brought together at the delay point or control point of application.

As an alternative or in addition to controlling a roller of the pair of delivery rollers, at least one roller of a pair of calender rollers arranged downstream of the drafting device can be provided in the second regulating circuit or in a third regulating circuit. It is hereby possible, for example, to coordinate the rotational speeds of the delivery roller pair and the calender roller pair to create a synchronous loudness such that no distortion occurs between these two roller pairs. With such a construction, it is therefore not absolutely necessary for the drawn fiber sliver to leave the drafting device at a constant outlet speed.

Particularly preferably, at least one low-pass filter is connected upstream of a first setpoint stage in the first regulating circuit. The voltage signals preferably released by the measured value delay unit therefore first pass through this minimum At least a low pass before they are switched to a setpoint level in the first control loop (actual values). This setpoint stage also preferably receives the speed of a main motor (setpoints) determined via a tachogenerator in order to determine a setpoint for a first control drive from these signals. This first control drive then drives - as in the prior art - into a differential gear which drives the mechanical scanning gear as well as the lower rollers of the input and middle roller pair in a known manner.

In the second regulating circuit, at least one high-pass filter is particularly preferably connected upstream of a second setpoint stage. In addition to the high-frequency voltage signals from the strip cross-section measuring device (actual values), the voltage signals corresponding to the speeds of the main motor are also preferably applied to the second setpoint stage (setpoints). A second control drive, which is used to drive machine elements with a low inertial mass, is preferably connected downstream of the output of the second setpoint stage. Such a machine element is preferably a roller of the pair of delivery rollers.

The second control drive advantageously drives into a second differential gear, which advantageously also receives its basic speed from the main motor. The second control drive thus swings symmetrically, corresponding to the thick and thin places of the at least one sliver, around the speed 0.

Alternatively, the second control drive, which is provided in the second regulating circuit for regulating out the high-frequency measurement signal components, can be designed for direct control of at least one roller of the corresponding pair of rollers - preferably a pair of delivery rollers and / or a pair of calender rollers. In this embodiment, no differential gear is therefore necessary in the second regulating circuit. Of course, this requires precise control of the control drive, which in this case does not oscillate around the speed 0.

In an advantageous alternative embodiment of the invention, the lower frequency range in the first regulating circuit is limited by a low-pass filter of at least first order, the signals in the upper frequency range being formed by subtracting the low-pass signal output from the original measurement signal. Are preferred here In the upper frequency range or in the second regulating circuit, amplitude and phase errors of the original measurement signals are taken into account, which were blocked by the low-pass filter or only passed through incorrectly.

In an alternative embodiment, the upper frequency range is limited downwards by a high-pass filter of at least first order, the signals in the lower frequency range being formed by subtracting the high-pass signal output from the original measurement signal. This automatically compensates for possible amplitude and phase errors, i.e. there are no jumps in amplitude or phase.

In an advantageous variant of the invention, machine elements which comprise drafting system rollers and which have an overall higher moment of inertia than machine elements with an overall lower moment of inertia are used as a low pass. Parts of the machine with a relatively high moment of inertia are thus used as a frequency-separating low-pass filter. The measurement signals pass through the first regulating circuit and are also branched off into the second regulating circuit. To check the low-pass filter effect, a tachometer generator can expediently be provided, which measures the rotational speeds of at least one of the drive elements, in particular one of the rollers, this roller being part of the machine elements with a high moment of inertia.

In a special embodiment according to the variant described above, the output of a first setpoint stage in the first regulating circuit is connected to the input of a setpoint stage in the second regulating circuit. In this embodiment, the measurement signal is not necessarily split up following the measurement delay unit by means of a low and high pass. Rather, the measurement signal of the strip cross-section measuring device can be applied directly to the setpoint stage in the first regulating circuit after conversion in the signal converter. The output signal of this setpoint stage then serves on the one hand to generate a control signal for the drive elements in the first regulating circuit - particularly preferably with the aid of a first regulating drive and a differential gear - and on the other hand in the form of a setpoint as an input signal for a setpoint stage in the second regulating circuit. The actual value for the second setpoint stage is preferred here by measuring the of frequency components converted in amplitude and phase are provided to the machine in the first regulating circuit, for example by connecting a tachometer generator to one of the center rollers, which produces the actual values mentioned for the second setpoint stage. The high-pass filter for the second regulating circuit is thus realized in principle by the machine itself, without any other filters being required, the frequency components of lower frequencies that can be used by the machine in the first regulating circuit and measured by the measuring signal, which includes all frequencies, to be processed in total in the second setpoint stage be subtracted.

The voltage signals generated by a tachogenerator can advantageously be applied to the input of the setpoint stage of the second regulating circuit in accordance with the rotational speeds, for example of a central roller or an input roller. These voltage values of the tachometer generator can be synchronized with a clock generator, which is connected to the strip cross-section measuring device, before they are switched to the input of the setpoint stage of the second regulating circuit.

Instead of just one belt cross-section measuring device, several such measuring devices can also be used in front of the drafting system.

The at least one strip cross-section measuring device can be designed, for example, as a mechanical scanning device. Alternatively or additionally, a microwave sensor with a resonator can be used.

Advantageous developments of the invention are characterized by the features of the subclaims.

Various exemplary embodiments of the invention are explained in more detail below with reference to the figures. Show it:

Figure 1 is a schematic circuit arrangement according to the prior art;

Figure 2 shows a schematic circuit arrangement according to a first embodiment of the invention; Figure 3 shows a schematic circuit arrangement according to a second embodiment of the invention;

FIG. 4 shows a schematic circuit arrangement according to a third embodiment, and

Figure 5 shows a schematic circuit arrangement according to a fourth embodiment.

The various embodiments of the invention to be discussed below are based on the prior art shown in FIG. 1. Other drive concepts and circuit arrangements are, however, also encompassed by the inventive concept.

According to FIG. 2, the strip cross-section fluctuations are mechanically determined using a strip cross-section measuring device 8. In the context of this invention, the term “strip cross-section fluctuations” also includes strip-mass fluctuations, strip thickness fluctuations, strip volume fluctuations or similar terms. The measured values for the strip cross-section fluctuations are converted into digital voltage signals in a signal converter 10 and sent to a measured value delay unit 12, which is used, for example, as hardware - or software-implemented FIFO memory (first-in-first-out) is also connected to the band cross-section measuring device 8, which generates a pulse corresponding to a specific sliver section length, for example 1.5 mm, and which The number of impulses is also passed on to the measured value delay unit 12. Depending on the running time of the fiber sliver FB from the sliver cross-section measuring device 8 to the desired delay point or control point of application in the drafting unit formed by the drafting roller pairs 2a, 2b, 3a, 3b, 4a, 4b, the decelerations become voltage signals from the measured value delay unit 12 to a low-pass filter 20 in a first regulating circuit. After passing through the low pass, which for example allows frequencies in a frequency range of approximately 0 to approximately 3 Hz, the correspondingly filtered voltage signals are passed on to a first setpoint stage 21 in the first regulating circuit (actual values). In addition, a voltage value is applied by a tachometer generator 16, which determines the speed of a main motor 14 and in converts a corresponding voltage signal (setpoints). The output of the setpoint stage 21 is connected to a first control drive 22, which drives in a first differential gear 23. The first differential gear 23 receives the basic speed from the main motor 14, the speed of which can be set by a speed setting unit 15.

The first control drive 22 is preferably designed as a servo drive, which generates a control speed for the differential gear 23, which is preferably designed as a planetary gear. With this controlled output speed of the differential gear 23, both a scanning roller of the belt cross-section measuring device 8, the lower roller 2a of the input roller pair and the lower roller 3a of the middle roller pair are driven. The speeds of the rollers 2a and 3a are not necessarily the same. For example, it is possible to drive them at a fixed speed ratio.

The second regulating circuit according to the invention includes a high-pass filter 30, at the input of which the voltage values of the measured value delay unit 12 are given. The high-pass filter 30 filters the voltage signals and allows, for example, frequencies of approximately 3 Hz to approximately 100 Hz. The voltage signals filtered in this way are switched to a second setpoint stage 31 of the second regulating circuit (actual values). The second setpoint stage 31 also receives the speed of the main motor 14 (setpoints) converted into voltage values by the tachometer generator 16. The second setpoint stage 31 determines from these signals a control speed for a second variable speed drive, advantageously a servo drive. The second control drive 32 drives in a second differential gear 33 of the second regulating circuit, this second differential gear 33 likewise receiving its basic speed from the main motor 14. With this controlled output speed of the second differential gear 33, the lower roller 4a of the pair of delivery rollers is driven. The two control loops thus implement an inlet regulation with a superimposed outlet regulation, the second regulating drive oscillating symmetrically around the speed 0. An additional delay is not produced on average by the phasing out regulation.

According to the embodiment shown in FIG. 2, the longer-wave band cross-section fluctuations can be caused by the lower-mass machine elements. mechanical scanning gear of the belt cross-section measuring device 8, first differential gear 23, rollers 2a, 3a - can be compensated to a sufficient extent. The higher-frequency fluctuations in the cross-section of the strip can be regulated by means of the outlet regulation by controlling the roller 4a of the pair of delivery rollers. At the control point of application, the frequency ranges are brought together again, so that wear on, for example, motor drive belts, caused by the large bandwidth of the signals, can be reduced. Wear due to the acceleration of large masses and increased energy consumption for driving these masses, which in the prior art is partly ineffective due to the impossibility of regulating higher-frequency band cross-section fluctuations, can be reduced.

In the embodiment of FIG. 2 (and analogously to that of FIGS. 3-5), the regulating processor comprises the measured value delay unit 12, the low pass 20, the high pass 30, the first setpoint stage 21 and the second setpoint stage 31. These elements are mapped in software in the regulating processor ,

The embodiment according to FIG. 3 differs from that of FIG. 2 in that there is no separate high-pass filter for filtering out the voltages in accordance with the low-frequency band cross-section fluctuations. Rather, on the one hand, the unfiltered voltage signals from the measured value delay unit 12 and the voltage signals filtered by a low-pass filter 20 (corresponding to FIG. 2) are connected to a subtractor 135. The subtractor 135 supplies output values which only contain the high-frequency signal components of the band thickness fluctuations and outputs these as setpoints to a second, multiplying setpoint stage 131 of the second regulating circuit. The second setpoint stage 131 is therefore preceded by a subtractor 135 in which the low-frequency measurement signals of the first regulating circuit are subtracted from the measurement signal containing all frequencies. The actual values for this second setpoint stage 131 are - similar to the embodiment according to FIG. 2 - obtained from a tachometer generator 16, which converts the speed of the main motor 14 into a corresponding voltage signal. Otherwise, the mode of operation in the embodiment according to FIG. 3 is analogous to that in FIG. 2. FIG. 4 shows a third embodiment of the invention. The first regulating circuit with a first setpoint stage 221, a first regulating drive 22 and a first differential gear 23 are unchanged from the embodiment according to FIG. 2 (only the low-pass filter 20 is missing). A superimposed outlet regulation according to the invention is realized in this embodiment in that the output of the first setpoint stage 221 is not only given to the first control drive 22, but also as setpoints to a second, subtracting setpoint stage 231 of a second regulating circuit. The actual values for this second setpoint stage 231 are determined from voltage values which are generated by a tachometer generator 116 which, in the exemplary embodiment shown, determines the rotational speed of the upper roller 3b of the middle roller pair. For example, the speed could also be tapped from one of the rollers 2a, 2b, 3a.

In other words, the machine itself realizes a high-pass filter in the second regulating circuit, the tachometer generator 116 converting the frequency components, i.e. the amplitude and phase, of the machine in the first regulating circuit. Measured signal components of relatively low frequency, measures in order to subtract them from the total signal containing all frequency components in the second setpoint stage 231.

As a result of the comparison or subtraction of the target and actual values, the second target value stage 231 determines target values corresponding to the high-frequency measurement signal components for a second control drive 32, which generates a control speed for a second differential 33 from this target value. With this controlled output speed of the second differential gear 33, the lower roller 4a of the pair of delivery rollers is driven. As a result, the desired distortion is achieved in the main drafting zone, formed by the pair of center rollers and the pair of delivery rollers, so that the strip cross-section fluctuations of the incoming strip or strips FB can be regulated.

In the embodiment according to FIG. 5, a low-pass filter 20 and a high-pass filter 30 are again provided, similar to that of FIG. 2, which split the measurement signal components of the band cross-section measuring device 8 into low-frequency signal components and high-frequency signal components. Of course, a plurality of filters can also be provided for the respective frequency range, as is also the case with the corresponding embodiments described above. The main difference in the execution 5 compared to that of Figure 2 is that the control speed generated by the second control drive 32 is not given in a differential gear, but is switched directly to the lower roller 4a of the pair of delivery rollers. It should be noted that it is of course also possible to drive the upper rollers of the different roller pairs in this and in the preceding embodiments. By directly controlling the roller 4a, the second differential gear can be saved. However, the coupling of the inlet regulation and the outlet regulation is dispensed with in this embodiment. Rather, the outlet regulation by means of the second control drive can produce an additional delay, so that the delivery speed is not necessarily constant. In this case, it is advisable for the second control drive 32 to additionally drive a pair of calender rolls connected downstream of the drafting device or a take-off device for pulling off the drawn sliver, so that the pair of delivery rolls and the pair of calender rolls feed the sliver synchronously.

The invention can also be used in spinning machines with individual drives. It is essential that band cross-section fluctuations are regulated in at least two control loops from signals received in front of the drafting system, in order in particular to be able to take into account the different moments of inertia of different machine parts in these control loops. A frequency-bandwidth increase can thus be obtained when regulating the stretching of the at least one fiber band.

Claims

Patent claims

1. Method for drawing at least one fiber sliver (FB) by means of a regulated spinning machine, in particular a card or draw frame, which has roller pairs (2a, 2b, 3a, 3b, 4a, 4b) arranged one behind the other, the mass cross section of the at least one fiber sliver upstream of the roller pairs (2a, 2b, 3a, 3b, 4a, 4b), characterized in that on the basis of the measurement signals at least one roller (2a, 3a) of a first roller pair (2a, 2b, 3a, 3b) over a first Regulation circuit and at least one roller (4a) of a second pair of rollers (4a, 4b) can be controlled via a second regulation circuit.

2. The method according to claim 1, characterized in that the rollers (2a, 4a, 4a) of different roller pairs (2a, 2b, 3a, 3b, 4a, 4b) are driven on the basis of the belonging of measurement signal components to different frequency ranges.

3. The method according to claim 2, characterized in that low-frequency measurement signal components for controlling machine elements, including rollers (2a, 3a), with higher mass moment of inertia and higher-frequency measurement signal components for

Control of machine elements, including rollers (4a), with a lower moment of inertia.

4. The method according to any one of the preceding claims, characterized in that the measurement signal components are assigned to at least a lower and an upper frequency range.

5. Device for drawing at least one sliver (FB), in particular for carrying out the method according to one of the preceding claims, with at least one upstream and one downstream pair of rollers (2a,

2b, 3a, 3b, 4a, 4b), with at least one upstream of these roller pairs (2a, 2b, 3a, 3b, 4a, 4b) arranged belt cross-section measuring device (8) for detecting the mass cross-section of the at least one sliver (FB), characterized by at least two regulating circuits, with at least one roller (2a, 3a) of a first being based on the measurement signals via the first regulating circuit Roller pairs (2a, 2b, 3a, 3b) and at least one roller (4a) of a second roller pair (4a, 4b) can be controlled via the second regulating circuit.

6. The device according to claim 5, characterized in that in the first control circuit machine elements, including rollers (2a, 3a), with a higher moment of inertia based on low-frequency measurement signal components and in the second control circuit machine elements, including rollers (4a), with a lower moment of inertia can be controlled by higher-frequency measurement signal components.

7. Apparatus according to claim 5 or 6, characterized in that the first regulating circuit has a lower frequency range and the second regulating circuit has an upper one

Frequency range are assigned.

8. Device according to one of claims 5 to 7, characterized by hardware and / or software implemented frequency filters for limiting the frequency ranges.

9. Device according to one of claims 5 to 8, characterized in that the lower and the upper frequency range are substantially without gap or overlap.

10. Device according to one of claims 5 to 9, characterized in that the lower frequency range comprises frequencies in the range of about 0 - 3 Hz and the upper frequency range frequencies in the range of about 3 - 100 Hz.

11. Device according to one of claims 5 to 10, characterized in that the lower and the upper frequency range are selected such that the machine elements with higher or lower moment of inertia can be driven essentially lossless.

12. Device according to one of claims 5 to 11, characterized in that in the first regulating circuit in each case one roller (2a) of a pair of input rollers (2a, 2b) and a pair of central rollers (3a, 3b) and in the second regulating circuit a roller (4a) of a pair of delivery rollers (4a, 4b) can be controlled.

13. The device according to one of claims 5 to 12, characterized in that the control takes place in such a way that the control starting point in the delay field (6) formed by the pair of central rollers (3a, 3b) and pair of delivery rollers (4a, 4b) for the first and the second Regulation loop is identical.

14. Device according to one of claims 5 to 13, characterized in that in the second control circuit at least one roller of a pair of calender rollers can be controlled.

15. The device according to one of claims 5 to 14, characterized in that at least one low-pass filter (20) is connected upstream of a first setpoint stage (21) in the first regulating circuit.

16. The device according to one of claims 5 to 15, characterized in that the output signals of the first setpoint stage (21) are connected to the input of a first control drive (22).

17. Device according to one of claims 5 to 16, characterized in that in the second regulating circuit, at least one high-pass filter (30) is connected upstream of a second setpoint stage (31; 131; 231).

18. Device according to one of claims 5 to 17, characterized in that the output signals of the second setpoint stage (31; 131; 231) are connected to the input of a second control drive (32).

19. Device according to one of claims 5 to 18, characterized in that the first control drive (22) and / or the second control drive (32) drive in a first or second differential gear (23; 33).

20. Device according to one of claims 5 to 19, characterized in that the control drive (32) of the high-frequency measurement signal components regulating the second control circuit is designed for direct control of at least one roller (4a) of the associated roller pair (4a, 4b).

21. Device according to one of claims 5 to 20, characterized in that the lower frequency range is limited by a low-pass filter of at least first order and the signals in the upper frequency range are formed by subtracting the low-pass signal output from the original signal.

22. Device according to one of claims 5 to 21, characterized in that in the higher frequency range, amplitudes and phase errors can be taken into account, which occur in the lower frequency range by signals in the blocking range of the low-pass filter.

23. Device according to one of claims 5 to 20, characterized in that the upper frequency range is limited downwards by a high-pass filter of at least first order and the signals in the lower frequency range are formed by subtracting the high-pass output signal from the original signal.

24. Device according to one of claims 5 to 23, characterized in that machine elements including rollers (2a, 2b, 3a, 3b), which have an overall higher moment of inertia than machine elements including rollers (4a, 4b) with an overall lower moment of inertia, can be used as a low pass.

25. The device according to claim 24, characterized in that a tachometer generator (116) for determining the low-pass filter effect on at least one drive element, in particular one of the rollers (2a, 2b, 3a, 3b), is provided.

26. Device according to one of claims 5 to 25, characterized in that the first regulating circuit comprises a first setpoint stage (221), at the input of which the measurement signals of the at least one strip cross-section measuring device (8) can be applied and whose output signals can be given as input signals to a second setpoint stage (231) in the second regulating circuit.

27. The device according to one of claims 5 to 26, characterized in that the setpoint stage (221) of the second control circuit, the actual speed values of a roller pair (3a, 3b) converted into voltage signals can be connected.

28. Device according to one of claims 5 to 27, characterized in that the setpoint stages (21, 31; 121, 131; 221, 231) of the first and / or of the second control circuit include the actual speed values converted into voltage signals

Drive motor (14), in particular the main motor of the spinning machine can be connected.

29. Device according to one of claims 5 to 28, characterized in that the at least one tape cross-section measuring device (8) is designed as a mechanical scanning device or microwave-based scanning device for at least one sliver (FB).