EP1529127B1 - Method and device for drafting at least one sliver - Google Patents

Description

The invention relates to a method for drawing at least one sliver by means of a regulated Spinnerelmaschine, in particular carding machine or track, according to the preamble of claim 1. Furthermore, the invention relates to a device for stretching at least one sliver according to the preamble of claim. 4

Spinning machines such as carding or stretching serve the purpose of forming a uniform as possible textile material from the submitted textile material. For this purpose, the spinning machines often have a regulated drafting system to control in accordance with the determined fluctuations on the basis of measured in front of the drafting device strip cross-section fluctuations in the direction of strip running delay elements. In the case of stretching, these drafting elements are formed, for example, by a plurality of roller pairs arranged one behind the other, between which the fiber sliver or slivers are clamped along the respective so-called nip line in the transverse direction of the strip. Since the pairs of rollers have different circumferential speeds which increase in the direction of travel of the strip, the fiber composite consisting of one or more slivers is stretched and made uniform. In order to form a feedback in the closed loop or to control the homogenization and possibly to trigger a machine stop in case of excessive tape number fluctuations a second tape cross-section measuring device is also provided at the exit of the drafting system in most cases.

For scanning mechanical scanning devices have prevailed as far as possible. For example, before the drafting system, the Rieter line RSB D30 has a pair of scanning disks with mutually parallel axes, one of the scanning disks being arranged stationary and the other scanning disk is designed to be mobile. The sliver (s) are passed in a gap between a circumferential groove of the first scanning disk and a peripheral ring of the second scanning disk, the movable scanning disk being deflected in accordance with the mass variations of the sliver (s). The deflection movements are converted by a signal converter into electrical voltage values and delivered to a regulating processor for controlling the roller pairs of the drafting system.

In particular, in spinning machines in which the scanning gear and the roller pairs are interconnected via, for example, a differential gear, the ausregulierbare frequency range with respect to the band cross-section fluctuations is relatively limited. Due to the large inertia of such an arrangement, a desired balancing over a wide frequency range of long-wave fluctuations (so-called A% values) up to Regulierlängen of a few inches at high delivery speeds is not possible. In addition, the machine parts wear, caused by the large bandwidth of the signal contents and the associated acceleration of large masses, and the energy consumption are relatively high.

In FIG. 1 a regulated drafting system is shown, in which a sliver FB passes through a mechanical belt cross-section measuring device 8 and is then guided into a drafting system formed by three drafting roller pairs 2a, 2b, 3a, 3b, 4a, 4b. The tape cross-section measuring device 8 is formed by two scanning disks, which have already been described above.

One of the two scanning discs is coupled to a clock generator 11, which generates a certain number of pulses per revolution of this Tastscheibe. Furthermore, the movable scanning disc is connected to a signal converter 10, which converts their deflection movements into electrical voltage values. These voltage values are then sent to a Meßwertverzögerungseinheit 12 passed, which also receives a number of clocks from the clock 11, which represent a measure of the speed of the current through the belt cross-section measuring device 8 sliver FB. According to these clocks from the clock 11, the voltage values in the Meßwertverzögerungseinheit 12, which represents an electronic memory in the form of a FIFO (First-In-First-Out), according to the traversed by the sliver path between the band cross-section measuring device 8 and the drafting device are retained. When the sliver with the strip piece to be leveled reaches the notional arrears in the drafting zone of the drafting system, the corresponding measured value is released by the Meßwertverzögerungseinheit 12 and made a corresponding action in response to the respective measured value. The distance between the measuring location of the Abtastwalzenpaares and the default location is called Regeleinsatzpunkt. For this purpose, the measured value delay unit 12 forwards the measured values to an algorithm unit 13 which calculates the speed of the drafting 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 variable speed drive 22 drives in a differential gear 23, which drives the stationary Abtastscheibe the band cross-section measuring device 8, the lower roller 2a of the pair of input rollers and the lower roller 3a of the middle roller pair. The differential gear 23 receives from a main motor 14 a base speed, which is adjustable via an intermediate between the main motor 14 and the differential gear 23 Drehzahleinstelleinheit 15.

The main motor 14, in turn, directly drives the lower roller 4a of the pair of delivery rollers, thereby obtaining a constant belt discharge speed. Accordingly, only the input roller pair and the middle roller pair are used for the regulation.

From the US 5,134,755 a method and a device is known in which a first control loop for the pre-delay and a second control loop for the main delay is provided. The pre-delay is set constant, while in the main delay both short-term and long-term disturbances or high and low frequency components in the nonwoven fabric are adjusted.

It is an object of the present invention, the method and the device of the type mentioned in such a way that a more precise distortion of one or more slivers is obtained.

This object is achieved in the method of the type mentioned by the features of claim 1.

This object is further achieved in a device of the type mentioned by the features of claim 4.

The advantages of the invention are to be seen in particular in the fact that the scanning signals are processed in front of the drafting in at least two Regulierkreisen, thus increasing the flexibility and accuracy in the control of the drafting elements or rollers. The at least two regulating circuits can react to different signal contents and thus assume a distribution of the driving 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 drive, can be driven.

Particularly preferably, the measured signal components of the at least one band cross-section measuring device are subdivided with regard to their frequency into at least two frequency ranges. Based on the affiliation of Meßsignalanteilen to different frequency ranges then the rollers of different roller pairs can be controlled. In this way also the regulation in the frequency domain is shared. Thus, each frequency band can be distributed according to its energy requirements on adapted machine elements.

It is advisable to use low-frequency measuring signal components, i. Long-wave band cross-section fluctuations, to use for controlling machine elements or drive elements with a higher moment of inertia. Accordingly, higher-frequency measurement signal components can be used to control drive elements with a low mass moment of inertia. Due to the low inertia, these machine elements can accelerate or decelerate faster, so that these machine elements can also follow the higher-frequency Meßsignalanteilen. Overall, a more precise regulation is obtained, whereby both longer-wave and shorter-wave band cross-section fluctuations can be optimally regulated.

A defined signal processing is advantageous if the measurement signal components of the strip cross-section measuring device connected upstream of the drafting system are allocated to at least one lower and one upper frequency range. In order to be able to utilize as many frequency components of the band cross-section fluctuations as possible, the lower and upper frequency ranges are preferably close to one another, particularly preferably substantially continuous, or overlapping.

Preferably, the upper frequency range is chosen such that a substantially lossless processing of the machine elements with a lower mass moment of inertia is possible. Likewise, the lower frequency range is preferably chosen such that a substantially lossless processing of the machine elements with a higher mass moment of inertia is possible.

It has proved to be advantageous if 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. However, these frequency ranges are not to be regarded as fixed, but can advantageously be selected or adjusted depending on the regulating distance and / or material to be distorted or other parameters. Also, the mentioned maximum frequency of 100 Hz is not a technical condition. 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 measured signal components to different frequency ranges. In preferred embodiments, hardware and / or software-implemented frequency filters are used for this purpose.

Preferably, in each case one roller of the pair of input rollers and of the middle roller pair is driven in the first regulating circle, while in the second regulating circle a roller of the delivery roller pair is actuated. Contrary to the state of the art described above, the pair of delivery rollers is therefore also used for regulation. In accordance with its low mass inertia, it is thus possible to regulate higher-frequency band cross-section fluctuations by controlling the delivery roller pair. Since this discharge regulation produces no additional delay on average, eliminates the known disadvantages of discharge regulations, which in particular consist in that the tape delivery speed varies and thus problems in these known machines with regard to a clean filing of the warped sliver in a sliver can. The described preferred variant of the invention, however, in principle forms an inlet regulation with superimposed outlet control. The basic advantage and the Ausregulierung low-frequency band fluctuations up to 3 Hz, for example, are made using the low-frequency regulation, in principle, the known regulation, for example, the Rieter route RSB D30 corresponds. At this delay then the upper frequency band is modulated by the higher-frequency regulation in the drafting system. This higher frequency control corresponds to a precise CV% control with the CV% value defined as CV% = s / x x 100 where CV% is the coefficient of variation (percent band nonuniformity), s is the standard deviation and x is the mean of all samples ,

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

The control in the first and second Regullerkreis is preferably such that the Regeleinsatzpunkt or default point in the delay line formed by the middle pair of rollers and pair of delivery rollers for both Regulierkreise is identical. This means that the delay point for both regulating circuits is identical and no Meßwertverzögerung the two Regulierkreise each other - using a FIFO memory or similar. - is needed. In other words, the different frequency ranges are merged at the default point or control point.

As an alternative or in addition to the control of a roller of the delivery roller pair, at least one roller of a calender roller pair arranged downstream of the drafting system can be provided in the second regulation circuit or in a third regulation circuit. It is thus possible, for example, to tune the rotational speeds of the delivery roller pair and the Kalanderwalzepaares to create a synchronous operation to each other so that no delay between these two roller pairs occurs. It is therefore not absolutely necessary by means of such a construction that the stretched sliver leaves the drafting system at a constant outflow speed.

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

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

Advantageously, the second control drive drives in a second differential gear, which advantageously also receives its base speed from the main engine. The second control drive thus oscillates symmetrically, corresponding to the thick and thin areas of the at least one sliver, about the speed 0.

Alternatively, the second control drive, which is provided in the second regulating circuit for balancing the high-frequency Meßsignalanteile, for direct control of at least one roller of the corresponding pair of rollers - preferably pair of delivery rollers and / or Kalanderwalzenpaar - formed be. In this embodiment, therefore, no differential gear in the second regulating circuit is necessary. Of course, in this case a more precise control of the control drive is necessary, which does not oscillate in this case by the speed 0.

In an advantageous alternative embodiment of the invention, the lower frequency range in the first regulating circuit is limited by a first order low-pass filter, wherein the signals in the upper frequency range are formed by subtracting the low-pass signal output from the original measuring signal. Preferably amplitude and phase errors of the original measuring signals are taken into account in the upper frequency range or in the second regulating circuit, which have been blocked by the low-pass filter or have only been transmitted incorrectly.

In an alternative embodiment, the upper frequency range is limited by a high pass of at least first order downwards, wherein the signals in the lower frequency range are formed by subtracting the Hochpaßsignalausgangs from Ursprungmeßsignal. This automatically compensates for possible amplitude and phase errors, i. there are no amplitude or phase jumps.

In an advantageous variant of the invention, machine elements comprising drafting rollers and having an overall higher mass moment of inertia than machine elements having an overall lower mass moment of inertia are used as low-pass filters. Parts of the machine with a relatively high moment of inertia are thus used even as a frequency-separating low-pass filter. The measuring signals in this case pass through the first regulating circuit and are also branched off into the second regulating circuit. For controlling the low-pass filter effect, a tachogenerator 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 mass moment of inertia.

In a specific embodiment according to the variant described above, the output of a first setpoint stage in the first regulation circuit is connected to the input of a setpoint stage in the second regulation circuit. In this embodiment, a splitting of the measurement signal is not necessarily made following the Meßverzögerungseinheit means of a low and high pass. Rather, the measurement signal of the band cross-section measuring device can be switched directly to the setpoint level in the first Regulierkreis after conversion in the signal converter. The output signal of this setpoint stage is then used on the one hand to generate a control signal for the drive elements in the first Regullerkrels - particularly preferably by means of a first variable speed 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 Regulierkreis. In this case, the actual value for the second setpoint stage is preferably provided by measuring the frequency components converted in amplitude and phase by the machine in the first regulating circuit, for example by connecting a tachogenerator to one of the center rollers which produces the mentioned actual values 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 need for other filters, the frequency components of lower frequencies which can be used by the machine in the first regulating circuit being measured and the measuring signal in the second setpoint stage comprising all frequencies, to be processed in its entirety 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 of, for example, a center roller or an input roller. These voltage values of the tachogenerator can be synchronized with a clock, which is connected to the belt cross-section measuring device, before they are switched to the input of the setpoint level of the second regulating circuit.

Instead of just one Bandquerschnittsmeßeinrichtung several such measuring devices can be used before the drafting.

The at least one tape 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.

Figur 1

eine schematische Schaltungsanordnung gemäß dem Stand der Technik;

Figur 2

eine schematische Schaltungsanordnung gemäß einer ersten Ausführungsform der Erfindung;

Figur 3

eine schematische Schaltungsanordnung gemäß einer zweiten Ausführungsform der Erfindung;

Figur 4

eine schematische Schaltungsanordnung gemäß einer dritten Ausführungsform, und

Figur 5

eine schematische Schaltungsanordnung gemäß einer vierten Ausführungsform.

In the following, various embodiments of the invention will be explained in more detail with reference to FIGS. Show it:

FIG. 1

a schematic circuit arrangement according to the prior art;

FIG. 2

a schematic circuit arrangement according to a first embodiment of the invention;

FIG. 3

a schematic circuit arrangement according to a second embodiment of the invention;

FIG. 4

a schematic circuit arrangement according to a third embodiment, and

FIG. 5

a schematic circuit arrangement according to a fourth embodiment.

The various embodiments of the invention to be discussed below are based on the in FIG. 1 illustrated prior art. However, other drive concepts and circuit arrangements are also included in the concept of the invention.

According to the FIG. 2 The band cross-section fluctuations are determined mechanically via a band cross-section measuring device 8. Within the scope of this invention, the term "band cross-section fluctuations" also encompasses band mass fluctuations, band-thickness fluctuations, band volume fluctuations or similar terms. The measured values for the band cross-section fluctuations are converted into digital voltage signals in a signal converter 10 and applied to a measured value delay unit 12 which is designed, for example, as a hardware or software-implemented first-in-first-out (FIFO) memory. To the strip cross-section measuring device 8, a clock 11 is further connected, which generates a pulse according to a particular sliver length, for example, 1.5 mm, and also passes the pulse number to the Meßwertverzögerungseinheit 12. In accordance with the running time of the sliver FB from the belt cross-section measuring device 8 to the desired default point in the drafting system formed by the drafting roller pairs 2a, 2b, 3a, 3b, 4a, 4b, the delayed voltage signals are passed from the Meßwertverzögerungseinheit 12 to a low-pass filter 20 in a first Regulierkreis After passing through the low-pass filter which, for example, transmits frequencies in a frequency range from about 0 to about 3 Hz, the correspondingly filtered voltage signals are forwarded to a first setpoint stage 21 in the first regulating circuit (actual values). In addition, a voltage value from a tachogenerator 16 is switched on, which determines the rotational speed of a main motor 14 and converts it into a corresponding voltage signal (nominal values). The output of the setpoint stage 21 is applied to a first variable speed drive 22, which drives in a first differential gear 23. The basic speed receives the first differential gear 23 from the main motor 14, the speed of which is adjustable by a speed setting unit 15.

The first variable speed 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. It is possible, for example, to drive it in a fixed speed ratio.

The second regulating circuit according to the invention includes a high-pass filter 30 to the input of which the voltage values of the measuring value delay unit 12 are given. The high-pass filter 30 filters the voltage signals and allows, for example, frequencies of about 3 Hz - about 100 Hz. The thus filtered voltage signals are switched to a second setpoint level 31 of the second regulating circuit (actual values). The second setpoint stage 31 also receives the speed of the main motor 14 (setpoint values) converted by the tachogenerator 16 into voltage values. The second setpoint stage 31 determines from these signals a control speed for a second variable speed drive, advantageously in turn a servo drive. The second variable speed drive 32 drives in a second differential gear 33 of the second regulating circuit, this second differential gear 33 also receives its base speed from the main motor 14. With this controlled output speed of the second differential gear 33, the lower roller 4a of the delivery roller pair is driven. The two regulating circuits thus realize an inlet regulation with a superimposed outlet regulation, the second regulating drive oscillating symmetrically about the speed 0. An additional delay is not produced by the discontinuation regulation on average.

According to the in FIG. 2 illustrated embodiment, the longer-wave band cross-section fluctuations by the mass-carrier machine elements - mechanical scanning gear of the tape cross-section measuring device 8, first differential gear 23, rollers 2a, 3a - be compensated to a sufficient extent. The higher-frequency band cross-section fluctuations are ausregulierbar by means of the outlet control by driving the roller 4a of the pair of delivery rollers. At the Regeleinsatzpunkt the frequency ranges are brought together again, so that wear of, for example, motor drive belt, caused by the large bandwidth of the signals can be reduced. Also, the wear by the acceleration of large masses and increased energy consumption for driving these masses, which is in the prior art due to the impossibility of Ausregulierung of higher-frequency band cross-section fluctuations partially ineffective, can be reduced.

The Regulierprozessor includes in the embodiment of FIG. 2 (as well as those of the Figures 3 - 5 ) the measurement delay unit 12, the low-pass filter 20, the high pass filter 30, the first setpoint stage 21 and the second setpoint stage 31. These elements are mapped in software in the regulation processor.

The embodiment according to the FIG. 3 is different from the one of FIG. 2 in that no separate high-pass filter is provided for filtering out the voltages corresponding to the low-frequency band cross-section fluctuations. Rather, on the one hand, the unfiltered voltage signals from the Meßwertverzögerungseinheit 12 and by a low-pass filter 20 (corresponding to the FIG. 2 On the other hand, filtered voltage signals are switched to a subtractor 135. The subtracter 135 provides output values which only contain the high-frequency signal components of the band thickness fluctuations and outputs these as set values to a second multiplier setpoint stage 131 of the second regulation circuit. The second setpoint stage 131 is thus preceded by a subtracter element 135 in which the low-frequency measurement signals of the first regulation circle are subtracted from the measurement signal containing all frequencies. The actual values for this second setpoint level 131 are - similar to the embodiment according to the FIG. 2 Obtained from a tachogenerator 16, which converts the speed of the main motor 14 into a corresponding voltage signal. Otherwise, the operation in the embodiment according to the FIG. 3 analogous to that of FIG. 2 ,

In the FIG. 4 a third embodiment of the invention is shown. The first regulating circuit with a first setpoint stage 221, a first variable speed drive 22 and a first differential gear 23 are compared to the embodiment according to the FIG. 2 unchanged (only the low-pass filter 20 is missing). A superimposed outflow regulation according to the invention is realized in this embodiment in that the output of the first setpoint stage 221 is not only applied to the first variable speed drive 22, but also as setpoint values to a second, subtractive setpoint stage 231 of a second regulation circle. The actual values for this second setpoint stage 231 are determined from voltage values that are generated by a tachogenerator 116, which determines the speed of the upper roller 3b of the middle roller pair in the illustrated embodiment. It could, for example, the speed of one of the rollers 2a, 2b, 3a tapped.

In other words, in the second regulating circuit, a high pass is realized by the machine itself, and the tacho-generator 116 detects the frequency and amplitude converted by the machine in the first regulating circuit, i. Measuring signal components of relatively low frequency, measures to subtract these from the total frequency signal containing total signal in the second setpoint stage 231.

As a result of the comparison or the subtraction of the desired and actual values, the second setpoint stage 231 determines the setpoint values corresponding to high-frequency measured signal portions for a second control drive 32 which generates a control speed for a second differential 33 from this setpoint value. With this controlled output speed of the second differential gear 33, the lower roller 4a of the delivery roller pair is driven. As a result, the desired delay change is achieved in the main drafting zone, formed by the middle roller pair and delivery roller pair, so that the band cross-section fluctuations of the incoming belt or bands FB can be adjusted.

In the embodiment according to the FIG. 5 are similar to those of FIG. 2 - In turn, a low-pass filter 20 and a high-pass filter 30 are provided, which split the Meßsignalanteile the band cross-section measuring device 8 in low-frequency signal components and high-frequency signal components. Of course, as is also the case with the corresponding, previously described embodiments, a plurality of filters may be provided for the respective frequency range. The essential difference of the embodiment according to the FIG. 5 opposite to that of FIG. 2 is that the control speed generated by the second control drive 32 is not placed in a differential gear, but is switched directly to the lower roller 4a of the delivery roller pair. It should be noted that, of course, in this as well as in the preceding embodiments, a drive of the upper rollers of the various pairs of rollers is possible. By direct control of the roller 4a, the second differential gear can be saved. However, in this embodiment, the coupling of the inlet regulation and the outlet regulation is dispensed with. Rather, an additional delay can be produced by the outlet regulation by means of the second control drive, so that the delivery speed is not necessarily constant. In this case, it makes sense if the second control drive 32 additionally drives a calender roller pair downstream of the drafting system or a pull-off device for drawing off the drawn sliver, so that the delivery roller pair and the calender roller pair synchronously convey the sliver.

The invention can also be used in spinning machines with individual drives. It is essential that from signals obtained before the drafting system Band cross-section fluctuations are regulated in at least two Regulierkreisen, in particular to be able to take into account the different moments of inertia of different machine parts in these Regulierkreisen. It can thus be obtained a frequency bandwidth increase in the regulation of the stretching of the at least one sliver.

Claims (27)

1. Method for the drafting of at least one fiber sliver (FB) by means of a regulated spinning machine, particularly a carding machine or draw frame comprising pairs of rollers (2a, 2b, 3a, 3b, 4a, 4b) which are disposed one behind another, wherein the mass cross-section of the (at least one) fiber sliver is measured upstream of the pairs of rollers (2a, 2b, 3a, 3b, 4a, 4b), wherein, based on the measuring signals, at least one roller (2a, 3a) of a first pair of rollers (2a, 2b, 3a, 3b) is actuated through a first auto-leveling circuit and at least one roller (4a) of a second pair of rollers (4a, 4b) is actuated through a second auto-leveling circuit, characterized in that based on the appurtenance of measuring signal portions to different frequency ranges, the rollers (2a, 3a, 4a) of different pairs of rollers (2a, 2b, 3a, 3b, 4a, 4b) are actuated.
2. Method as in claim 1, characterized in that the low-frequency measuring signal portions are used to control machine elements, including rollers (2a, 3a) with greater moment of mass inertia, and higher-frequency measured signal portions are used to control machine elements, including roller (4a) with lower moments of mass inertia.
3. Method as in one of the preceding claims, characterized in that the measuring signal portions are assigned to at least one lower and one upper frequency range.
4. Device for the drafting of at least one fiber sliver (FB), in particular by applying 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 sliver cross-section measuring device (8) located upstream of these pairs of rollers (2a, 2b, 3a, 3b, 4a, 4b) to detect the mass cross-section of the (at least one) fiber sliver (FB), wherein at least two auto-leveling circuits are provided and wherein, based on the measuring signals, at least one roller (2a, 3a) of a first pair of rollers (2a, 2b, 3a, 3b) can be actuated through the first auto-leveling circuit, and at least one roller (4a) of a second pair of rollers (4a, 4b) through the second auto-leveling circuit,
   characterized in that machine elements, including rollers (2a, 3a), with higher moment of mass inertia can be controlled in the first auto-leveling circuit based on low-frequency measuring signal portions and machine elements, including rollers (4a), with lower moment of mass inertia in the second auto-leveling circuit based on higher-frequency measuring signal portions.
5. Device as in claim 4, characterized in that a lower frequency range is assigned to the first auto-leveling circuit and an upper frequency-range to the second auto-leveling circuit.
6. Device as in one of the claims 4 or 5, characterized by frequency filters in hardware and/or software form to delimit the frequency ranges.
7. Device as in one of the claims 4 to 6, characterized in that the lower and upper frequency ranges adjoin each other essentially without a gap or overlap each other.
8. Device as in one of the claims 4 to 7, characterized in that the lower frequency range comprises frequencies in the range of approximately 0 to 3 Hz and the upper frequency range frequencies in the range of approximately 3 to 100 Hz.
9. Device as in one of the claims 4 to 8, characterized in that the lower and the upper frequency ranges are selected in such manner that the machine elements with higher or lower moment of mass inertia can be actuated essentially without loss.
10. Device as in one of the claims 4 to 9, characterized in that one roller (2a) of a pair of input rollers (2a, 2b) and of a pair of central rollers (3a, 3b) can be actuated in the first auto-leveling circuit, and one roller (4a) of a pair of delivery rollers (4a, 4b) in the second auto-leveling circuit.
11. Device as in one of the claims 4 to 10, characterized in that actuation takes place in such manner that the starting point of auto-leveling in the drafting field (6) formed by the central pair of rollers (3a, 3b) and the pair of delivery rollers (4a, 4b) is identical for the first and for the second auto-leveling circuit.
12. Device as in one of the claims 4 to 11, characterized in that in the second auto-leveling circuit at least one roller of a pair of calendar rollers can be actuated.
13. Device as in one of the claims 4 to 12, characterized in that at least one low-pass filter (20) precedes a first target-value step (21) in the first auto-leveling circuit.
14. Device as in one of the claims 4 to 13, characterized in that the output signals of the first target-value step (21) are switched to the input of a first auto-leveling drive (22).
15. Device as in one of the claims 4 to 14, characterized in that at least one high-pass filter (30) precedes a second target-value step (31; 131; 231) in the second auto-leveling circuit.
16. Device as in one of the claims 4 to 15, characterized in that the output signals of the second target-value step (31; 131, 231) are switched to the input of a second auto-leveling drive (32).
17. Device as in one of the claims 4 to 16, characterized in that the first auto-leveling drive (22) and/or the second auto-leveling drive (32) drives a first or second differential gear (23; 33).
18. Device as in one of the claims 4 to 17, characterized in that the auto-leveling drive (32) of the second auto-leveling circuit which levels the high-frequency signals is designed for direct actuation of at least one roller (4a) of the appertaining pair of rollers (4a, 4b).
19. Device as in one of the claims 4 to 18, characterized in that the lower frequency range is delimited by a low-pass filter of at least first order and the signal in the upper frequency range are formed by subtraction of the deep-pass filter signal output from the original signal.
20. Device as in one of the claims 4 to 19, characterized in that amplitude and phase errors occurring in the lower frequency range through signals within the lock-out range of the deep-pass filter can be taken into account in the higher frequency range.
21. Device as in one of the claims 4 to 20, characterized in that the upper frequency range is delimited downward by a high-pass filter of at least first order and in that the signals in the lower frequency range are formed by subtraction of the high-pass filter output signal from the original signal.
22. Device as in one of the claims 4 to 21, characterized in that machine elements, including rollers (2a, 2b, 3a, 3b), with overall higher moment of mass inertia than machine elements, including rollers (4a, 4b), with an overall lower moment of mass inertia are used as low-pass filter.
23. Device as in claim 22, characterized in that a tachometer generator (116) is provided on at least one drive element, in particular on one of the rollers (2a, 2b, 3a, 3b) to determine the effect of the low-pass filter.
24. Device as in one of the claims 4 to 23, characterized in that the first auto-leveling circuit comprises a first target value step (221) at the input of which the measuring signals of the (at least one) sliver cross-section measuring device (8) can be applied and the output signals of which can be given as input signals to a second target value step (231) in the second auto-leveling circuit.
25. Device as in one of the claims 4 to 24, characterized in that the actual speed values converted into voltage signals of a pair of rollers (3a, 3b) can be switched up to the target value step (221) of the second auto-leveling circuit.
26. Device as in one of the claims 4 to 25, characterized in that the actual speed values converted into voltage signals of a driving motor (14), in particular of the main motor of the spinning machine, can be switched up to the target value steps (21, 31; 121, 131; 221, 231) of the first and/or the second auto-leveling circuit.
27. Device as in one of the claims 4 to 26, characterized in that the (at least one) sliver cross-section measuring device (8) is designed as a mechanical scanning device or as a scanning device based on microwaves for at least one fiber sliver (FB).

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