Method for controlling an adjustable working pressure on a combing machine, and combing machine

Abstract

The invention relates to a method for controlling an adjustable working pressure p on a combing machine (1) during a combing operation to produce a combed sliver (3). In a rolling time window (tstart, tend), a control and regulating unit (56) detects a temporal profile (90) of an actual value x detected by a measuring device (55) and analyses extreme values (91) of the temporal profile (90) of the actual value x, wherein the control and regulating unit (56) carries out a pressure adaptation process (100) if a predetermined number of the extreme values (91) lies outside a predetermined tolerance range (88) by the desired value (87), wherein the pressure adaptation process (100) comprises the following steps: a starting step (101), at which the working pressure p of the current pressure value pact is adjusted to an increased pressure value pinc, which is at least 1.2 times the current pressure value pact, or if the 1.2 times the current pressure value pact lies above the maximum value pmax, corresponds to the maximum value pmax; and an optimization step (103) if, at the working pressure p adjusted to the increased pressure value pinc, the extreme values (91) lie within the tolerance range (88) by the desired value (87), wherein the working pressure p is successively adapted and adjusted to an optimized pressure value popt, at which the extreme values (91) have a predetermined minimum deviation (89) from the desired value (87) and remain within the tolerance range (88) by the desired value (87); or a warning step (107) if, at the working pressure p adjusted to the increased pressure value pinc, at least one of the extreme values (91) lies outside the tolerance range (88) by the desired value (87). The invention further relates to a combing machine (1) which is configured for carrying out the method according to the invention.

Description

[0001] Title: Method for controlling an adjustable working pressure on a combing machine and combing machine

[0002] Description

[0003] The present invention relates to a method for regulating an adjustable working pressure on a combing machine during a combing process for producing a combing sliver, wherein the combing machine comprises: a plurality of combing heads for forming individual combing head slivers, each with a tear-off device comprising at least one tear-off roller pair with a rotationally drivable tear-off roller, in particular a tear-off bottom roller, and a counter roller, in particular a counter roller, and at least one roller loading device having at least one actuating element assigned to the counter roller; a pressure supply system connected to the roller loading devices via pressure connections and comprising at least one pressure regulator configured to apply the working pressure, which can be adjusted between a minimum value and a maximum value, to at least a subset of the actuating elements;a compression device for combining the individual combing head bands into the combing band; a measuring device for detecting an actual value of a measured variable associated with the combing band; and a control and regulation unit configured to control the at least one pressure regulator based on a recurring target-actual comparison between the actual value and a predetermined target value for adjusting the working pressure. Furthermore, the present invention relates to such a combing machine.

[0004] The pressure level required to produce good sliver quality for each individual head comber sliver and ultimately for the delivered comber sliver, as well as for smooth combing machine operation, depends, among other things, on parameters such as the feed material (cotton type, fiber fineness, fiber length), batting weight, number of combing cycles, top roller hardness, bottom roller crown, room climate, required break-off curve, and / or noil quantity. Setting a suitable working pressure to produce the desired sliver quality based on the given parameters is usually carried out manually in a setup run prior to the production process. The setup run is always necessary, for example, when changing batches – i.e., when the material to be processed is changed, or when the number of combing cycles is adjusted, or when one of the aforementioned parameters changes.However, adjusting the working pressure is also necessary if, for example, the strip quality deteriorates during strip production. To improve quality, the counter-roller pressure is then increased.

[0005] DE4229448A1 discloses a combing machine with a system in which the working pressure with which the bottom tear-off rollers are pressed against the counter rollers is adjustable. The bottom tear-off rollers are fixed to the frame and are mounted only for rotation. The working pressure is adjusted manually by the machine operator on the combing machine.

[0006] A disadvantage is that manually adjusting the working pressure requires regular monitoring of the resulting sliver quality by the operator. Since this is time-consuming, operators often set the working pressure to a maximum value to ensure good sliver quality. However, this also increases the comber's energy consumption and wear on the counter rollers and bearings. Furthermore, excessively high contact pressure results in increased heat generation.

[0007] DE102011052367A1 discloses a system for regulating the load on roller pairs in a drafting system of a textile machine. The degree of load is to be controlled using a control system based on machine data from the textile machine and / or data from the material to be drawn. It is proposed to increase the load for a specific operating period after a piecing process. Sensor electronics are to record not only the surface temperatures of the rollers but also the average thickness of the fiber sliver and the irregularities remaining in the fiber sliver. If the quality of the outgoing fiber sliver does not meet requirements, in addition to changing the pre-draft and / or main draft of the drafting system, a signal can also be transmitted to loading elements to automatically regulate the degree of load on the roller pairs during the drawing process.

[0008] EP3966373B1 discloses a combing machine with a controllable pressure regulator for automatically adjusting the pressure force with which a pressing device of the respective combing head presses a pressure cylinder of a detaching cylinder pair against a detaching cylinder. Using a control and regulation unit coupled to the pressure regulator, the pressure force can be adjusted depending on a predetermined speed of the combing machine. The use of the pressure regulator to adjust the pressure force is intended to allow the different moments of inertia between the pressure cylinder and the detaching cylinder to be addressed, depending on the speed of the combing machine. The adjustable pressure force is intended to prevent an excessive deviation between the speed of the pressure cylinder and the speed of the detaching cylinder, i.e., to minimize slippage.This is intended to improve the soldering process for producing the combed sliver web, compared to detaching cylinder units, where the pressure force via the pressure device always remains constant at the same pressure level, regardless of the set speed of the combing machine. The pressure regulator is also intended to be used to adjust the pressure cylinder's pressure force if, after the soldering process with the detaching cylinder unit, the quality of the combed fiber web does not fall within a specified quality range. The quality of the combed fiber web is to be defined on the basis of sliver uniformity by the so-called CV value, with the fineness of the outgoing sliver being continuously monitored by means of a movable calender disk in conjunction with a non-contact inductive sensor or an eddy current sensor. One such quality monitoring system is known, for example, as the Rieter Quality Monitor (RQM).This sensor is intended to monitor the thick spots of the nonwoven fabric online, with the thick spots serving as an indicator of whether the tear-off cylinder pairs are satisfactorily adjusted for the soldering process. Accordingly, if the nonwoven fabric quality is insufficient, the sensor for monitoring thick spots should transmit a data signal to the control and regulation unit via a signal line. The control and regulation unit should then control the pressure regulator in such a way that the pressure cylinder of the cylinder pair receives sufficient contact pressure to restore optimal nonwoven quality.

[0009] The object of the present invention is to further develop a method for regulating an adjustable working pressure during a combing process for producing a combed sliver in such a way that the causes of quality fluctuations can be assessed and remedied more accurately and quickly, in order to consistently produce a combed sliver with a specified sliver quality. Furthermore, the object of the present invention is to further develop a combing machine in such a way that the causes of quality fluctuations can be assessed and remedied more accurately and quickly, in order to consistently produce a combed sliver with a specified sliver quality.

[0010] The level of the set working pressure with which the counter rollers are pressed against the tear-off rollers, or the resulting contact pressure between the tear-off roller pairs, has a direct influence on the web quality at the respective combing head and ultimately on the sliver quality of the produced combed sliver. Furthermore, the contact pressure directly influences the energy consumption of the combing machine and the wear of the counter rollers and their bearings. Furthermore, an overly high contact pressure leads to unnecessarily high heat generation. It is therefore desirable that the working pressure is always set so that the produced sliver quality corresponds to the desired sliver quality, avoiding both too poor and too good sliver quality.

[0011] This object is achieved on the basis of a method of the type mentioned at the outset in that the control and regulating unit records a temporal profile of the actual value (also called actual profile or temporal actual profile) in a rolling time window and analyses extreme values ​​of the actual profile, wherein the control and regulating unit carries out a pressure adaptation process if a predetermined number of the extreme values ​​lie outside a predetermined tolerance range around the setpoint value, wherein the pressure adaptation process comprises the following steps: an initial step in which the working pressure is set from the current pressure value to an increased pressure value which corresponds to at least 1.2 times the current pressure value or, if 1.2 times the current pressure value is above the maximum value, to the maximum value;and an optimization step if the extreme values ​​at the working pressure set to the increased pressure value lie within the tolerance range around the setpoint, wherein the working pressure is successively adjusted and set to an optimized pressure value at which the extreme values ​​have a predetermined minimum deviation from the setpoint and remain within the tolerance range around the setpoint; or a warning step if at least one of the extreme values ​​at the working pressure set to the increased pressure value lies outside the tolerance range around the setpoint; comprises.;

[0012] Continuous recording of the actual value enables real-time analysis, allowing the control and regulation unit to react to deviations between the actual value and the specified setpoint. The actual value is therefore a current actual value of the measured variable. If this deviates, the sliver quality of the produced combed sliver does not correspond to the sliver quality desired by the combing machine operator, or rather the specified sliver quality to which the combing machine has been set. The combing machine then produces a combed sliver whose sliver quality is either too poor or too good. In order to react to this, the control and regulation unit analyzes the extreme values ​​of the actual temporal progression in a rolling time window and adjusts the working pressure if the specified number of extreme values ​​lies outside the specified tolerance range around the setpoint. The basic idea of ​​the rolling time window is that the time window covers a specific period of time and progresses continuously.With each new actual value measurement, the oldest actual value is removed from the rolling time window to make room for the integration of the most recent data. Thus, only the most recent actual values ​​within the rolling time window are considered for analysis. The time span can, for example, be between 1 second and 1 hour, although particularly good results in terms of process stability have been achieved with a time span between 10 seconds and 5 minutes.

[0013] Typically, the actual value fluctuates over time. The extreme values ​​are preferably local extremes. In other words, the extreme values ​​can represent peaks or troughs in the time course. Likewise, the extreme values ​​can also be the largest or smallest actual values ​​in the rolling time window.

[0014] Specifying the number of extreme values ​​has a direct impact on process stability. Only when the number of extreme values ​​is reached does the control and regulation unit react by adjusting the working pressure. This can prevent the control and regulation unit from adjusting the pressure even in the event of small or short-term fluctuations in the actual value. For example, the pressure adjustment process is only carried out if at least two of the extreme values ​​lie outside the tolerance range around the setpoint. The number of extreme values ​​can be, for example, two, three, four, five, six, seven, eight, nine, ten, or even more than ten. In order to produce sufficient strip qualities, the specified number of extreme values ​​can be a maximum of 50, more preferably a maximum of 30, and even more preferably less than 20. It is also possible for the number of specified extreme values ​​to be exactly one.

[0015] If the actual value deviates from the setpoint to such an extent that the specified number of extreme values ​​lies outside the tolerance range, the control and regulation unit starts the pressure adjustment process with the aim of determining whether an incorrectly set working pressure is the cause of the changed strip quality and, if so, to determine the currently optimal pressure value and adjust the working pressure accordingly. The tolerance range around the setpoint can, like the setpoint itself, be specified by the operator or be a value stored in the control and regulation unit. The size of the tolerance range has a direct impact on the sensitivity and accuracy of the setpoint / actual value comparison and, accordingly, on how quickly the control and regulation unit reacts to deviations. For example, the tolerance range can be specified or stored by specifying a deviation as a percentage from the setpoint or by an absolute value.First, in the initial step the control and regulation unit controls at least one pressure regulator to adjust the working pressure from the current pressure value to the increased pressure value. This step enables a simple and reliable determination of whether the working pressure was set incorrectly. According to a first embodiment of the initial step, the adjustable working pressure is increased from the current pressure value to the maximum pressure. This leads to a particularly quick determination of whether the working pressure is the cause of the deterioration in strip quality. According to a second embodiment of the initial step, the current pressure value can be set to the increased pressure value, which corresponds to at least 1.2 times the current pressure value. However, the upper limit is that the working pressure can be increased up to a maximum value.The maximum value, like the minimum value, can be specified or preset limits for the working pressure on the machine and / or operator side. Typically, the minimum value is approximately 2 to 4 bar and more preferably at least approximately 3 bar. The maximum value can be approximately 5 to 8 bar and more preferably at least approximately 6.5 bar. This pressure range is particularly common when combing cotton, although other pressure ranges are also possible depending on the material to be combed.

[0016] By continuously recording the actual value, the control and regulation unit now analyzes the extreme values ​​of the actual time profile in the rolling time window, while the working pressure is set to the increased pressure value. To prevent the analysis from being distorted by actual values ​​recorded before the pressure increase, the time window can be restarted with the pressure increase. If the actual value and thus also the extreme values ​​in the rolling time window return to the tolerance range around the target value, a working pressure that was currently set too low was the cause of the strip quality deviation from the desired strip quality. The control and regulation unit then starts the optimization step.However, if at least one of the extreme values ​​or the specified number of extreme values ​​lies outside the tolerance range around the target value at the working pressure set to the increased pressure value, the working pressure level currently has no influence on the sliver quality, which is why the control and regulation unit then executes the warning step. Another cause for the deviation of the actual value from the target value could be, for example, a machine defect, a blockage in one of the combing heads, or something similar.

[0017] The optimization step serves to determine the optimized pressure value by successively adjusting the working pressure starting from the increased pressure value. The extreme values ​​exhibit a specified minimum deviation from the target value and remain within the tolerance range around the target value. Specifying the minimum deviation allows the working pressure to be adjusted downwards as long as the extreme values ​​remain within the specified tolerance range. This enables the working pressure to be set to a pressure value, namely the optimized pressure value, which is only high enough to achieve the required sliver quality. This enables effective pressure optimization, which not only ensures compliance with the specified sliver quality but also allows the working pressure to be reduced. This improves the efficiency of the combing process.According to a first embodiment of the optimization step, the working pressure is gradually adjusted by gradually reducing the working pressure from the increased pressure value until the optimized pressure value is reached. The successive reduction of the adjustable working pressure can be continuous or incremental, for example, in 0.2 bar increments. Larger or smaller increments are also possible. The optimization step can be accelerated by gradually reducing the working pressure.

[0018] According to an alternative embodiment of the optimization step, it can comprise the following substeps: First, the adjustable working pressure is successively reduced starting from the increased pressure value until at least one of the extreme values ​​lies outside the tolerance range around the setpoint. During the successive reduction, the temporal progression of the actual value is recorded and a minimum required pressure value is determined at which the actual values ​​were last within the tolerance range around the setpoint. After the successive reduction, the minimum required pressure value can be defined as the optimized pressure value. Alternatively, the minimum required pressure value plus a specified safety margin can be defined as the optimized pressure value. This enables a particularly efficient search for the optimized pressure value.Temporarily falling below the tolerance range contributes to the robustness of the control system and helps achieve a stable working pressure setting. This can also be advantageous if system-related delays occur before a change in the working pressure is fully perceived. Temporarily falling below the tolerance range makes it possible to take such delays into account and adjust the working pressure accordingly. The successive adjustment, i.e., reducing or increasing, of the adjustable working pressure can be continuous or stepwise, for example, in 0.2 bar increments. Larger or smaller increments are also possible. The safety margin (offset) can be, for example, 5 percent, 10 percent, 15 percent, or an absolute value. In this way, sufficient tear-off roller pressure is guaranteed even with minor process fluctuations.This prevents excessive readjustment and leads to overall improved process stability.

[0019] After setting the working pressure to the optimized pressure value, the control and regulation unit can prompt the operator, for example via a connected display, to visually assess the web appearance at the combing heads. If irregularities, such as holes in the web, are detected, the working pressure can be increased by a percentage or absolute value. This can be specified by the operator, or the control and regulation unit can increase the optimized pressure value by the offset or adjust the offset. Furthermore, a camera connected to the control and regulation unit can be installed on each combing head. This camera observes the web appearance, for example in the area of ​​the web bowl or in the area of ​​the web joining, and transmits any irregularities as a signal to the control and regulation unit. In this way, pressure adjustment, in particular an increase based on the optimized pressure value, can take place automatically.Furthermore, it can be provided that the pressure adjustment process includes a pressure maximization step before the warning step if the increased pressure value is less than the maximum value. The working pressure is then initially set to the maximum value. If the extreme values ​​are now within the tolerance range around the target value, the optimization step is carried out after the pressure maximization step. If, however, at least one of the extreme values ​​is outside the tolerance range around the target value, the warning step is carried out. Instead of increasing the working pressure from the increased pressure value directly to the maximum value in the pressure maximization step, a gradual increase can also be carried out. This gradual increase can be more energy-efficient and minimizes wear on the tear-off rollers and bearing points.In the initial step and / or in the pressure maximization step, the current pressure value can be increased, for example, by at least 0.1 bar and more preferably by approximately 0.2 bar, 0.3 bar, 0.4 bar, 0.5 bar, 0.6 bar, 0.7 bar, 0.8 bar, 0.9 bar, 1.0 bar or even more than 1.0 bar. Likewise, the step-by-step increase starting from the current pressure value can be increased by at least 20 percent, 50 percent, 100 percent, 150 percent or 200 percent. Preferably, the control and regulation unit only carries out the warning step when at least one of the extreme values ​​of the actual temporal progression in the rolling time window lies outside the tolerance range around the target value, even with the working pressure set to the maximum value. It can then be assumed that an insufficient working pressure can be ruled out as the cause of the deterioration in strip quality.

[0020] The pressure adjustment process can include a waiting step before the warning step if at least one of the extreme values ​​at the working pressure set to the increased pressure value lies outside the tolerance range around the target value. After a time window has elapsed, the optimization step is executed if the extreme values ​​in the rolling time window lie within the tolerance range around the target value, or the warning step is executed if at least one of the extreme values ​​or the specified number of extreme values ​​in the rolling time window lies outside the tolerance range around the target value. If the increased pressure value is less than the maximum value, the pressure maximization step can be performed before the waiting step.The target / actual comparison that always runs in the background allows the control and regulation unit to further analyze the extreme values ​​of the actual temporal progression and only decides whether to execute the warning step or the optimization step after the wait step has expired. The wait step prevents the warning step from being executed even in the event of short-term production fluctuations. The wait step can cover a period that can be entered manually or stored in the control and regulation unit. For example, the period can be a certain number of seconds or minutes and can range from 10 seconds to 60 minutes, for example. A longer or shorter period may also be possible depending on the application. The warning step can include at least one of the following sub-steps: issuing an acoustic warning signal; issuing a visual warning signal; stopping the production run of the combing machine.In this way, the operator of the combing machine can be made aware that the level of the working pressure is not the cause of the deterioration in the sliver quality, but that another cause must be assumed.

[0021] Furthermore, it can be provided that the control and regulation unit executes a pressure reduction process if the specified number of extreme values ​​has an actual deviation from the target value that is smaller than the specified minimum deviation, or if the specified number of extreme values ​​is smaller than a lower tolerance limit of the tolerance range, wherein in the pressure reduction process the adjustable working pressure is successively adjusted from the current pressure value to a reduced pressure value at which the extreme values ​​have the specified minimum deviation from the target value and remain within the tolerance range around the target value. Specifying the minimum deviation allows the working pressure to be adjusted downwards while maintaining the desired sliver quality. This improves the efficiency of the combing process. The successive adjustment of the adjustable working pressure can also be carried out continuously or stepwise.The reduced pressure value can also be increased by the specified safety margin.

[0022] Furthermore, the actual value can be reproduced or represented by a sensor output signal from a sensor of the measuring device assigned to the combed sliver. This makes it possible to monitor the combed sliver quality using various parameters. The measuring device transmits the sensor output signals to the control and regulation unit, which in turn compares the incoming signals or the actual values ​​with the target value. The quality parameters selected for setting the working pressure can be freely selected, or parameters can be combined. The actual value can preferably represent the sliver mass of the combed sliver. The sliver mass can be specified in kilograms per meter. Parameters calculated from the sensor output signal or the sliver mass determined from it, such as deviation from the mean value, number of thin spots, number of thick spots, and CV values, can also be used as the actual value.For each parameter or actual value to be compared, a specific target value can be specified, whereby the target value can be subject to a defined deviation or tolerance range.

[0023] The sensor can be, for example, a non-contact inductive sensor or an eddy current sensor. Other types of distance sensors, displacement sensors, tactile sensors, optical sensors, ultrasonic sensors, inductive sensors, and so on are also possible. For example, the sensor can comprise a moving coil whose output signals are transmitted to the control and regulation unit. The measured variable can then describe, for example, the change in the inductance of the moving coil. The measured change in inductance can be converted into a voltage and forwarded to the control and regulation unit as the sensor's output signal. With an ultrasonic sensor, the measured variable can describe the propagation time of the ultrasonic signal, or with an optical sensor, the intensity of the received light or another optical variable. The sensor's output signals can, for example, be manually assigned to a belt mass during calibration.A deviation from the signal value can then be specified as a percentage that is tolerable and should define the tolerance range. As long as the tolerance range is not exceeded or undershot in accordance with the specifications with regard to the extreme values ​​and the minimum deviation is also maintained within the specifications, the working pressure and thus the contact pressure are set such that the desired strip quality is maintained, meaning that the control and regulation unit does not have to intervene to regulate it. Using a second calibration value, a deviation in the signal output voltage in volts can be assigned to a ground deviation. As long as the specifications are also met here, the working pressure is acceptable. All other variables can result from the change in the sensor output signal or the volt signal and can be calculated from this.

[0024] The sensor associated with the combed sliver is preferably located at the exit or runout of the combing machine. Furthermore, the combing machine can comprise at least one drafting system, whereby the sensor associated with the combed sliver can be located behind the drafting system. A combination of several sensors at different locations on the combed sliver and, if appropriate, on the individual head combed slivers is also conceivable.

[0025] The pressure supply system preferably operates pneumatically, although the pressure supply system can also in principle be a hydraulic pressure supply system. The actuating elements can in particular comprise pneumatic cylinders which are operated by the working pressure provided by the pressure supply in order to press the respective counter-roller against the tear-off roll by means of linear movements. The pressure supply system can be connected to a central or cross-machine pressure source or have its own pressure source. According to one aspect, a pressurized gaseous fluid can be air or a mixture of air and a gas. In one embodiment, the gaseous fluid used can be air, which is readily available and inexpensive to compress. In particular, the equipment for compressing air is readily available and is generally part of blower systems in a spinning mill.The pressure source of the pressurized gaseous fluid can therefore be an external pressure source, such as the compressed air source of the blower system, or it can be built into the combing machine. In an alternative embodiment, it can be a combination of an external pressure source and a built-in pressure source. At least one pressure regulator is provided to regulate the working pressure. In order to be able to individually adjust the working pressure applied to the respective control element, the pressure supply system can also comprise several pressure regulators. In this way, the respective control element or interconnected groups of subsets of control elements can be loaded with the individual working pressure.

[0026] The combing machine can comprise a single tear-off roller pair or two of the at least one tear-off roller pairs per combing head. In the latter variant, a first tear-off roller pair can be arranged upstream of a second tear-off roller pair of the two tear-off roller pairs in a transport direction of the combing head. The pressure supply system can be designed to apply a first adjustable working pressure to the at least one actuating element assigned to the first tear-off roller pair and a second adjustable working pressure to the at least one actuating element assigned to the second tear-off roller pair. In this way, for example, the second tear-off roller pair can be subjected to a lower working pressure than the first tear-off roller pair.This can be advantageous because the second detachment roller pair usually only performs conveying work, in contrast to the first detachment roller pair, which also has to separate the fiber sliver in order to comb out any loose fiber tuft. The different working pressures can be achieved by installing a first pressure regulator upstream of the roller loading devices of the combing heads assigned to the first detachment roller pairs, and a second pressure regulator upstream of the roller loading devices of the combing heads assigned to the second detachment roller pairs. Alternatively, each roller loading device can be connected to its own pressure regulator, so that at least one pressure regulator can be provided for each combing head. If the detachment roller pairs for each combing head are always to be loaded with the same working pressure, a structurally simpler solution can be to assign exactly one roller loading device to the counter rollers of both detachment roller pairs.

[0027] The optimization of the counter-roller pressure can take place in the transport direction. If a different, briefly different working pressure is applied to the counter-rollers, the optimization can also be carried out based on different criteria. For example, in the optimization step, the working pressure of both break-off roller pairs can initially be adjusted simultaneously from the increased pressure value to the optimized pressure value. Subsequently, the pressure reduction step can be carried out for the roller loading devices of the second break-off roller pairs in order to further reduce the working pressure applied to the adjusting elements for the second counter-rollers. It is also conceivable that only the working pressure of the counter-roller of the first break-off roller pair is optimized initially. For the second roller pair, the working pressure initially remains at the maximum value.After optimizing the working pressure on the first pairs of rollers, the working pressure on the second pairs of rollers can then be optimized in the next step.

[0028] The at least one pair of tear-off rollers comprises the respective tear-off roller, which can also be referred to as the lower tear-off roller, and the respective counter roller, which, due to its spatial arrangement above the lower tear-off roller, can also be referred to as the upper tear-off roller. Accordingly, the roller loading device can also be referred to as the upper roller loading device.

[0029] Furthermore, the object is achieved by a combing machine of the type mentioned at the outset in that the combing machine is configured to carry out the method described or according to the invention. The combing machine has a plurality of combing heads for forming individual combing head strips, each with a tear-off device comprising at least one tear-off roller pair with a rotationally drivable tear-off roller and a counter-roller and at least one roller loading device which has at least one actuating element assigned to the counter-roller; a pressure supply system which is connected to the roller loading devices via pressure connections and which comprises at least one pressure regulator which is configured to apply the working pressure, which can be adjusted between a minimum value and a maximum value, to at least a subset of the actuating elements; a compression device for combining the individual combing head strips to form a combing strip;a measuring device for detecting an actual value of a measured variable assigned to the combing sliver; and a control and regulation unit configured to control the at least one pressure regulator based on a recurring target-actual comparison between the actual value and a predetermined target value in order to adjust the working pressure. The combing machine offers the same advantages as the method according to the invention, and vice versa, so reference is made to the previous description.

[0030] The control and regulation unit is thus operatively connected to the at least one pressure regulator for adjusting the working pressure. The control and regulation unit receives information from the measuring device and, after appropriate alphanumeric processing, can output information to the at least one pressure regulator and control it to operate an active control loop.

[0031] As usual, the combing machine can have an operating unit through which the operator can enter operating inputs. The operating unit can be linked to the control and regulation unit. Furthermore, a (touch) display can be arranged on or near the combing machine. Likewise, the control and regulation unit can transmit and receive data to and from a mobile device, an output unit in a central control center of the spinning mill, etc. via a data interface. Furthermore, the control and regulation unit can have its own storage medium. The quality of the combing sliver, or the course of the actual value and / or the working pressure, can be permanently recorded over the operating time of the combing machine.

[0032] Further measures improving the invention are described in more detail below together with the description of a preferred embodiment of the invention with reference to the figures.

[0033] They show:

[0034] Figure 1 is a schematic representation of a combing machine according to the invention;

[0035] Figure 2 is a schematic representation of a drafting system and a combing machine outlet of the combing machine from Figure 1;

[0036] Figure 3 is a schematic representation of parts of a combing head of the combing machine of Figure 1;

[0037] Figure 4 is a schematic representation of parts of an alternative combing head of the combing machine of Figure 1;

[0038] Figure 5 shows a double-axis time series diagram with pressure and actual values, with the combing machine set to an operating pressure at which the required sliver quality is produced;

[0039] Figure 6 shows another dual-axis time series diagram showing pressure and actual values ​​while an initial step of a pressure adjustment process is being performed; Figure 7 shows a flowchart describing the pressure adjustment process;

[0040] Figure 8 shows a dual-axis time series diagram while an optimization step of the pressure adjustment process is performed;

[0041] Figure 9 is a dual-axis time series diagram with the operating pressure increased by a safety margin;

[0042] Figure 10 is a dual-axis time series diagram during which the initial step, a waiting step, and a warning step of the pressure adjustment process are performed; and

[0043] Figure 11 shows a dual-axis time series diagram while a pressure reduction process is performed.

[0044] Figure 1 shows a combing machine 1 for producing a combing sliver 3 with, here by way of example, eight combing heads 2, which is designed in a conventional manner to produce a combing sliver 3 from a material feed 4 made of natural fibers, such as cotton or blends, for example, viscose or viscose-cotton, or from chemical fibers and natural fibers. The combing machine 1 can also comprise fewer or more than the eight combing heads 2, for example, twelve or 16 combing heads. Each combing head 2 can be provided with a lap roll 5, as shown here, or alternatively, a sliver feed from fiber sliver cans. In a manner known per se, each combing head 2 produces a fiber web 60 from the provided lap roll 5, which is combined by a consolidation device 28, for example a web or strip forming funnel, into a single combing head strip 29 and deposited by means of a pair of take-off rollers 10 on a strip depositor or deposit table 35.Via this conveyor, the individual combing head bands 29 of all combing heads 2, arranged side by side on the deposit table 35 merely as an example, reach an optional drafting system 36 of the combing machine 1 and are then combined to form the combing band 3 in a compacting device 37, which may, for example, comprise a band forming funnel. The combing band 3 can be deposited in a spinning can at the combing machine outlet 61, for example, via a can depositor 38.

[0045] Figure 2 shows details of the drafting system 36. It is, in this case, a 2-zone drafting system or a 4-over-3 drafting system. It has three roller pairs 39, 40, 41, between which the drafting of the fiber composite from the individual combing head slivers 29 takes place, namely, in the sliver travel direction 59, coming from the combing heads 2 and pointing toward the combing machine outlet 61, an input roller pair 39, a middle roller pair 40, and an output roller pair 41. The roller pairs 39, 40, 41 each have a drafting system bottom roller 42, 43, 44 and a drafting system top roller 45, 46, 47, with a further drafting system top roller 48 being arranged on the drafting system bottom roller 44 of the output roller pair 41, which deflects the drawn fiber composite. In principle, it could also be a different drafting system, for example, a 5-over-4 drafting system. The input roller pair 39 and the middle roller pair 40 form a pre-drafting zone 49.A subsequent main drafting zone 50 is formed by the center roller pair 40 and the output roller pair 41. The drafting system bottom rollers 42, 43, 44 are rotatably mounted on a machine frame 51 of the combing machine 1. The drafting system 36 can be an uncontrolled or controlled drafting system. In order to be able to control the draft ratio, the drafting system bottom roller 44 of the output roller pair 41 can be driven by a first drive (not shown), the main motor, and determines the delivery speed of the combing machine 1. The drafting system bottom rollers 42, 43 of the input and center roller pair 39, 40 can be driven by a second drive (not shown), the control motor. Other drive concepts are also possible. The drafting system upper rollers 45, 46, 47, 48 are pressed against the drafting system lower rollers 42, 43, 44 by pressure elements 52 and are thus driven by frictional engagement.

[0046] Figure 3 shows details of the combing head 2, to which a cotton sliver 6 is fed from the cotton reel 5, in which winding rollers 8, 9 are set in rotation. The cotton sliver 6 reaches a feed cylinder 13 and is finally guided between an upper gripper 62 and a lower gripper 63 of a gripping device 14. This can be moved back and forth in an oscillating manner, so that a front region 64 of the lower gripper 63 approaches a first tear-off roller pair 30 of a tear-off device 65 arranged downstream of the gripping device 14 in the reel travel direction 59 and, in the reversing movement, increases the distance to the first tear-off roller pair 30 again. The tear-off device 65 also has a second tear-off roller pair 31 arranged downstream of the first tear-off roller pair 30 in the reel travel direction 59.

[0047] A circular comb 21 is rotatably mounted below the nipper assembly 14. Its comb segment 22 combs out the fiber tuft presented by the closed nipper assembly 14. The circular comb 21 can be connected to the nipper assembly 14 via a gear (not shown). Together with a top comb 23, short fibers, neps, and impurities are removed from the fiber material, which are then vacuumed away as so-called noil.

[0048] The two tear-off roller pairs 30, 31 each have a rotatably driven tear-off roller 68, 70 and a counter roller 69, 71. The tear-off rollers 68, 70 are mounted on the machine frame 51 in a frame-mounted manner and are driven by a drive device (not shown). The tear-off rollers can, for example, perform a so-called pilgrim-step movement, wherein the movement in the belt travel direction 59 is approximately twice as large as the movement of the fiber web 60 formed between the tear-off roller pairs 30, 31 back to the gripper apparatus 14. Instead of the pilgrim-step movement, the tear-off rollers can also be driven in a constant direction of rotation. In principle, however, the control of the adjustable working pressure functions independently of the tear-off curves that the tear-off rollers pass through with each comb cycle. The counter rollers 69, 71 are guided above the tear-off rollers 68, 70 in the area of ​​their bearings, fixed to the frame.The tear-off device 65 has a roller loading device 72, which is assigned to two counter-rollers 69, 71 and loads them with an adjustable working pressure p. In this way, the respective counter-roller 69, 71 is pressed against the assigned tear-off roller 68, 70, so that the rotational movement of the driven tear-off roller 68, 70 can be transmitted to the counter-roller 69, 71 by friction. The roller loading device 72 can span the tear-off roller pairs 68, 70 and can have an adjusting element 74 on each side in the longitudinal extension of the rollers, which is attached to one of the two ends of the counter-rollers 69, 71 and, for example, accommodates the bearings of the counter-rollers 69, 71 in bearing supports 76, 77. The adjusting elements 74 are connected to a pneumatic pressure supply system 78 of the combing machine 1 and can be designed, for example, as pneumatic actuators or pressure elements.For example, a spring element (not shown) can be arranged on each side opposite to the direction of action of the adjusting elements 74.

[0049] The roller loading device 72 has a pressure connection 79, via which it is connected to a pressure line 81 of the pressure supply system 78. This further comprises a central pressure source 84, not belonging to the combing machine 1 here, to which the pressure supply system 78 is connected. Furthermore, the pressure supply system 78 has, here merely as an example, a pressure regulator 83, to which the adjusting elements 74 of the roller loading devices 72 of all combing heads 2 are connected. The pressure source 84 supplies the pressure supply system 78 with an operating pressure, which can be adjusted to the working pressure p by the pressure regulator 83. The working pressure p is applied to the adjusting elements 74 and presses the counter rollers 69, 71 against the detachment rollers 68, 70.The level of the adjustable working pressure p, or the resulting contact pressure between the respective counter roller and the associated tear-off roller, has a direct influence on the web quality at the respective combing head 2 and ultimately on the sliver quality of the produced combed sliver 3. The working pressure can be adjusted between a minimum and a maximum value, whereby the minimum value can be, for example, approximately 3 bar and the maximum value approximately 6.5 bar. This pressure range is particularly advantageous when combing cotton, although other pressure ranges are also possible depending on the material to be combed. The contact pressure resulting between the counter roller and the tear-off roller of the respective tear-off roller pair is generally directly proportional to the working pressure exerted on the adjusting elements.

[0050] Figure 4 shows an alternative embodiment of the combing head 2 compared to Figure 3, which differs in the design of the roller loading device. Instead of just one roller loading device 72 per combing head 2, two roller loading devices 72, 73 are provided for each combing head 2.

[0051] A roller loading device 72, 73 assigned to the respective tear-off roller pair 30, 31 presses the respective counter-roller 69, 71 against the associated tear-off roller 68, 70. The respective roller loading device 72, 73 can span the associated tear-off roller pair 68, 70 and can have an adjusting element 74, 75 on each side in the longitudinal extension of the respective roller, which is attached to one of the two ends of the respective counter-roller 69, 71 and, for example, accommodates the bearing of the counter-roller 69, 71 in a bearing carrier 76, 77. The roller loading devices 72, 73 have pressure connections 79, 80, via which they are connected to pressure lines 81, 82 of the pressure supply system 78.The pressure supply system 78 has, here merely by way of example, two of the pressure regulators 83, 93, so that for each combing head 2, the adjusting elements 74 of the counter rollers 69 of the first tear-off roller pairs 30 can be connected to the first pressure regulator 83 and the adjusting elements 75 of the counter rollers 71 of the second tear-off roller pairs 31 can be connected to the second pressure regulator 93. In this way, the counter rollers 69 of the first tear-off roller pairs 30 and the counter rollers 71 of the second tear-off roller pairs 31 can be loaded with different working pressures p, namely p1, p2.

[0052] Alternatively, the pressure supply system 78 can, for example, have a separate pressure regulator for each actuating element 74, 75.

[0053] To monitor the sliver quality of the produced combed sliver 3, a measuring device 55 is provided with a sensor 54 assigned to the combed sliver 3. The measuring device 55 is configured to record an actual value x of a measured variable assigned to the combed sliver 3. In particular, the measuring device 55 can have a pair of sensing rollers 53 with a first sensing roller 85 and a second sensing roller 86, between which the combed sliver 3 is guided, wherein sliver mass fluctuations or sliver thickness changes lead to a displacement of the two sensing rollers 85, 86 relative to one another. For example, the first sensing roller 85 can be mounted fixedly to the machine frame 51, and the second sensing roller 86 can be mounted pivotably relative to the first sensing roller. The second sensing roller 86 can, in particular, be arranged spring-loaded against the first sensing roller 85. The sensor 54 can be configured to measure the distance or the change in distance between the two sensing rollers 85, 86.The sensor 54 can, for example, be a non-contact inductive sensor or an eddy current sensor, although other sensor types configured for distance changes are also possible. The sensor 54 can, for example, comprise a plunger coil to detect the change in eddy currents caused by the movement of a conductive metal (e.g., metal) of the pivotable, second sensing roller 86 or of a conductive component moved by the second sensing roller 86, in the immediate vicinity of which the plunger coil is arranged. In the sensor configuration described here as an example, the measured variable can represent the change in the inductance of the plunger coil. The actual value x can then describe the current change in inductance caused by the change in distance. The change in the inductance value is converted by the sensor 54 into an electrical signal and passed on as an output signal to a control and regulation unit 56.For this purpose, the control and regulation unit 56 is connected to the measuring device 55 or the sensor 54 via a connecting line 92, also called control line or regulation line.

[0054] A correlation curve or equation can be stored in the control and regulation unit 56, which represents the relationship between the measured change in inductance and the actual distance between the two sensing rollers 85, 86. This can be specified, for example, as part of a calibration run, in which a reference distance between the two sensing rollers 85, 86 can first be determined, which serves as the starting point for calibration. In a conventional manner, measurements are then carried out with the sensor 54 for various distances between the two sensing rollers 85, 86. The different distances are then usually assigned to strip masses. The measurements preferably cover the range of the expected distance changes, or the expected strip masses or strip mass fluctuations.The sensor 54 is advantageously configured such that the change in inductance in the range of expected distance changes is proportional to the change in the distance between the plunger coil and the conductive material. A target value 87 for the measured variable can be specified in the control and regulation unit 56, which is indicated by a dashed line in Figures 5, 6, and 7 to 11. To do this, the operator typically specifies a desired strip parameter, such as the strip mass (kilograms per meter), the mean value, the CV value, or the like. The desired strip parameter is then assigned by the control and regulation unit 56 to a defined distance between the sensing rollers 85, 86 using the correlation curve or equation. Furthermore, the operator can specify a tolerance range 88 around the target value 87 and / or a minimum deviation 89 from the target value 87.Likewise, the control and regulation unit 56 can access standard values ​​for the tolerance range 88 and / or the minimum deviation 89, which can be stored for different materials.

[0055] Furthermore, the control and regulation unit 56 can be coupled to a display device 57 or a display of the combing machine 1. Furthermore, an input field 58 can also be provided on the display device 57, via which the operator of the combing machine 1 can make inputs.

[0056] During a combing process, the combing machine 1 generates the combing sliver 3 from the material feed 4 in a conventional manner. The measuring device 55 continuously or repeatedly measures the actual value x of the measured variable assigned to the combing sliver 2 and transmits the output signals of the sensor 54 to the control and regulation unit 56. This performs a recurring target-actual comparison based on the real-time data. If the actual value x deviates from the target value 87 by more than a tolerated amount, the control and regulation unit 56 checks whether the contact pressure is the cause of the deviation and, if so, the control and regulation unit 56 regulates the adjustable working pressure p during the combing process. The control and regulation unit 56 is configured to control the pressure regulator or the pressure regulators 83, 93 based on the recurring target-actual comparison between the actual value x and the predetermined target value 87 for setting the working pressure p.For this purpose, the control and regulation unit 56 is connected to the at least one pressure regulator 83, 93 via a further connecting line 92, also called a control line or control line. Specifically, the control and regulation unit 56 analyzes extreme values ​​91 of an actual temporal profile 90 in a rolling time window in a recurring target-actual comparison, as shown in Figure 5. The basic idea of ​​the rolling time window is that the time window covers a specific time period Δt and progresses continuously. With each new actual value measurement, the oldest actual value is eliminated from the rolling time window in order to make room for the integration of the most recent actual value. Thus, only the current actual values ​​within the rolling time window are taken into account for the analysis. The rolling time window thus covers the range between tstart and t. end. off. The dashed representation of the actual curve 90 in Figure 54 to the left of tstart serves to illustrate which older actual values ​​are no longer included in the advancing time window. The time span Δt can, for example, be between 1 second and 1 hour, whereby the time span Δt here is 10 seconds as an example. In the actual curve 90 shown in Figure 5, it can be seen that in the rolling time window, the extreme values ​​91 and consequently also all of the actual values ​​x lie within the tolerance range 88 around the setpoint 87. In addition, the extreme values ​​91 have the specified minimum deviation 89 from the setpoint 87. The working pressure p currently provided by the pressure regulator 83 ac t is thus well adjusted for the sliver quality specified by the operator or when setting the combing machine 1.

[0057] Figure 6 shows that the working pressure p has been well adjusted until time ti. This is followed by several extreme values ​​91.1, 91.2, 91.3, 91.4 in the rolling time window, which is marked by t s t ar t and t e nd is specified, which lie outside the tolerance range 88. This exceeds the specified number of extreme values ​​that may lie outside the tolerance range 88 within the rolling time window. The number of extreme values ​​is specified as four, purely as an example. Upon registration of the fourth extreme value 91.4 at time t2, the control and regulation unit 56 performs a pressure adjustment process.

[0058] Figure 7 shows a flow chart of the pressure adjustment process, which begins with Start 100. Since the target-actual comparison is a continuous process, the control and regulation unit 56 also continuously performs this during the pressure adjustment process.

[0059] The control and regulation unit 56 raises the working pressure p from the current pressure value p in an initial step 101 ac t to an increased pressure value pinc, which, here as an example, corresponds to the maximum value p ma x. In principle, the working pressure p could also be increased to a lower pressure value than the maximum value. The control and regulation unit 56 can then check whether a suboptimally adjusted working pressure p was the cause of the deterioration in the delivered sliver quality of combed sliver 3.

[0060] If the extreme values ​​91 for the working pressure p set to the increased pressure value pinc lie within the tolerance range 88 around the setpoint 87, the control and regulation unit 56 decides at a decision point 102 that an optimization step 103 is to be carried out. For this purpose, the control and regulation unit 56 further analyzes the extreme values ​​of the actual curve 90 for a certain time, which can correspond to the time period Δt, in the rolling time window. Figure 6 shows that at time α, the working pressure p is set to the increased pressure value pinc, which here corresponds to the maximum value p max, was raised and the extreme values ​​91.5, 91.6, 91.7, 91.8, 91.9, 91.10 following the extreme value 91.4 are again within the tolerance range 88. Thus, with the working pressure p set to the increased pressure value pinc, no extreme value lies outside the tolerance range 88. To clarify the temporal sequence, the rolling time window is shown in Figure 6 at different times with t' s t a rt and t' en d and t" s t art and t"end are shown. It advances continuously and therefore overlaps. However, it is also clear that the extreme values ​​91.5, 91.6, 91.7, 91.8, 91.9, 91.10 are now within the limits of the minimum deviation 89. This means that while raising the working pressure p has improved the strip quality, the strip quality is now better than required. The working pressure p is set too high, and there is a lower working pressure with which the required strip quality could be achieved more efficiently.

[0061] In optimization step 103, the pressure value p inc set working pressure p is successively adjusted and set to an optimized pressure value at which the extreme values ​​91 have the specified minimum deviation 89 from the setpoint 87 and remain within the tolerance range 88 around the setpoint 87. For this purpose, the control and regulation unit 56 controls the pressure regulator 83 to successively reduce the working pressure p starting from the increased pressure value pinc, as shown in Figure 8. This can be done, for example, in 0.2 bar steps. The working pressure p is reduced until at least one of the extreme values ​​91 ' is outside the tolerance range 88 around the setpoint 87, as here with a pressure value pi that is too low for the required strip quality ow During the successive reduction, the control and regulation unit 56 records the time course of the actual value x and determines a minimum required pressure value p req, at which the actual value x was last in the tolerance range 88 around the setpoint 87. This was the case here, for example, at time t1, see Figure 8. Accordingly, the control and regulation unit 56 controls the pressure regulator 83 at time t2 to reduce the working pressure p from p m in again slightly to the minimum required pressure value p req This allows for an optimized pressure value p opt which corresponds to the pressure value p req In principle, the optimized pressure value p opt also the minimum required pressure value p req plus a specified safety margin to increase the process stability, as shown in Figure 9. The safety margin can, for example, be 5 percent of the minimum required pressure value p req At the end of 104, the pressure adjustment process ends with the setting of the operating pressure p to the pressure value p optduring the combing process, so that the combing process now takes place with the optimized pressure value p opt can be continued.

[0062] If, however, with regard to the flow chart according to Figure 7 and the representation of the actual curve 90 according to Figure 10, the control and regulation unit 56 recognizes at decision point 102 that in the rolling time window, with the working pressure p set to the increased pressure value p^c, at least one further extreme value 91 .5 lies outside the tolerance range 88 around the setpoint 87, it first carries out a waiting step 105, here at time t 1 (see Figure 10). After the expiration of a time window, which can, for example, correspond to the length of the time interval of the rolling time window, here 10 seconds, the control and regulation unit 56 makes a decision based on the actual curve 90 in the rolling time window, here with t lv s t ar t and t lv end limits, a decision is made at a further decision point 106, here at time t2 (see Figure 10). If the extreme values ​​91 lie within the tolerance range 88 around the setpoint 87, the optimization step 103 is executed. If, however, at least one of the extreme values, such as the extreme values ​​91.9, 91.10, 91.11 here, lies outside the tolerance range 88 around the setpoint 87, it can optionally be provided that the control and regulation unit 56 checks whether the increased pressure value already corresponds to the maximum value. This is already the case in the embodiment described here, so that a warning step 107 takes place at time t2. However, if the increased pressure value p^c is smaller than the maximum value p ma x, a pressure maximization step can first be carried out, whereby the working pressure p is set to the maximum value p max is set. If the extreme values ​​91 then lie within the tolerance range 88 around the target value 87, the optimization step 103 takes place; otherwise, the warning step 107 is carried out, as shown in Figure 10. In the warning step 107, an acoustic warning signal and / or a visual warning signal can be output, for example via the display device 57. In this way, the control and regulation unit 56 can inform the operator of the combing machine 1 that the working pressure p, or the level of the working pressure p, currently has no influence on the sliver quality and that there is another cause for the deviation of the actual value x from the target value 87. The control and regulation unit 56 can be coupled to further sensors in order to be able to narrow down the cause more precisely, for example a blockage on one of the combing heads.Warning step 107 may additionally or alternatively also provide for stopping the combing process of combing machine 1 to prevent damage to combing machine 1 and / or the continuation of the combing process with insufficient sliver quality. The print optimization process ends at step 108.

[0063] Furthermore, a pressure reduction process can be provided as a further process for regulating the adjustable working pressure p during the combing process. If the analysis of the extreme values ​​91 of the actual curve 90 in the rolling time window shows that the specified number of extreme values ​​91.1, 91.2, 91.3, 91.4 has an actual deviation from the target value 87 that is smaller than the specified minimum deviation 89, as shown in Figure 11, or if the specified number of extreme values ​​is smaller than a lower tolerance limit of the tolerance range, the control and regulation unit 56 carries out the pressure reduction process. For this purpose, it controls the pressure regulator 83 to successively reduce the adjustable working pressure p from the current pressure value p act to a reduced pressure value pdec, at which the extreme values ​​91.5, 91.6 lie outside the specified minimum deviation 89 from the setpoint and remain within the tolerance range 88 around the setpoint 87. This can be done in a similar way to the optimization step 103. This ends the pressure reduction process with the setting of the operating pressure p to the pressure value pdec during the ongoing combing process, so that the combing process now takes place with the reduced pressure value pdec, which corresponds to the pressure value p opt can be continued accordingly. In contrast to optimization step 103, the current working pressure p ac t, from which the pressure reduction process starts, is usually smaller than the maximum value p ma x, whereby in principle the optimized pressure value in the combing process can sometimes correspond to the maximum value if this is the only way to achieve the required sliver quality.

[0064] Maintaining the desired sliver quality and / or the deviation of the actual value x from the target value 87 can be indicated by lighting elements (not shown) arranged on the combing machine 1 according to predetermined lighting scenarios, as described, for example, in patent specification EP3371354B1 registered to the applicant. The lighting scenarios can, for example, include a running light with respect to at least some of the lighting elements to indicate the degree of deviation of the actual value x from the target value 87. Reference numerals

[0065] 1 combing machine 55 measuring device

[0066] 2 Combing head 56 control and regulation unit

[0067] 3 Combing belt 57 Display device

[0068] 4 Material template 58 input field

[0069] 5 cotton rolls 59 tape direction

[0070] 6 cotton wool band 60 fiber fleece

[0071] 8 Winding roller 61 Combing machine outlet

[0072] 9 Winding roller 62 Upper gripper

[0073] 10 pair of take-off rollers 63 lower pliers

[0074] 13 Feed cylinder 64 front area

[0075] 14 forceps device 65 tear-off device

[0076] 21 circular comb 68 tear-off roller

[0077] 22 Comb segment 69 Counter roller

[0078] 23 Top comb 70 Tear-off roller

[0079] 28 Consolidation device 71 Counter roller

[0080] 29 Single combing head belt 72 Roller loading device

[0081] 30 Tear-off roller pair 73 Roller loading device

[0082] 31 Tear-off roller pair 74 Adjusting element

[0083] 35 Storage table 75 Adjustment element

[0084] 36 drafting system 76 bearing supports

[0085] 37 Compression device 77 Bearing carrier

[0086] 38 Can rest 78 Pressure supply system

[0087] 39 Input roller pair 79 Pressure connection

[0088] 40 middle roller pair 80 pressure connection

[0089] 41 Output roller pair 81 Pressure line

[0090] 42 drafting device under roller 82 pressure line

[0091] 43 Stretching system below Ize 83 Pressure regulator

[0092] 44 drafting device under roller 84 pressure source

[0093] 45 drafting system top roller 85 feeler roller

[0094] 46 Drafting system top roller 86 Sensing roller

[0095] 47 Drafting system top roller 87 Target value

[0096] 48 Drafting system top roller 88 Tolerance range

[0097] 49 Pre-draft field 89 Minimum deviation

[0098] 50 Main distortion field 90 Actual course

[0099] 51 Machine frame 91 Extreme value

[0100] 52 Pressure element 92 Connecting line

[0101] 53 pair of sensing rollers 93 pressure regulator

[0102] 54 Sensor 100 Start 101 Initial step

[0103] 102 Decision Point

[0104] 103 Optimization step

[0105] 104 End

[0106] 105 Waiting step

[0107] 106 Decision Point

[0108] 107 Warning step

[0109] 108 End

[0110] P pressure

[0111] At Time span t Time x Actual value

Claims

Patent claims 1 . Method for regulating an adjustable working pressure p on a combing machine (1) during a combing process for producing a combing sliver (3), wherein the combing machine (1) comprises: a plurality of combing heads (2) for forming individual combing head slivers (29), each having a tear-off device (65) which comprises at least one tear-off roller pair (30, 31) with a rotationally drivable tear-off roller (68, 70) and a counter-roller (69, 71), and at least one roller loading device (72, 73) which has at least one adjusting element (74, 75) assigned to the counter-roller (69, 71); a pressure supply system (78) which is connected to the roller loading devices (72, 73) via pressure connections (79, 80) and comprises at least one pressure regulator (83) which is configured to supply at least a subset of the actuating elements (74, 75) with the pressure between a minimum value p m in and a maximum value p max to apply an adjustable working pressure p; a compression device (37) for combining the individual combing head bands (29) to form the combing band (3); a measuring device (55) for detecting an actual value x of a measured variable assigned to the combing band (3); and a control and regulating unit (56) which is configured to control the at least one pressure regulator (83) based on a recurring target-actual comparison between the actual value x and a predetermined target value (87) for adjusting the working pressure p;characterized in that the control and regulating unit (56) records a time profile (90) of the actual value x in a rolling time window (tstart, tend) and analyses extreme values ​​(91) of the time profile (90) of the actual value x, wherein the control and regulating unit (56) carries out a pressure adaptation process (100) if a predetermined number of the extreme values ​​(91) lies outside a predetermined tolerance range (88) around the target value (87), wherein the pressure adaptation process (100) comprises the following steps: an initial step (101) in which the working pressure p is increased from the current pressure value pact to an increased pressure value pj; nc which is at least 1.2 times the current pressure value p ac t or, if 1.2 times the current pressure value p ac t above the maximum value p ma x, the maximum value p ma x; and an optimization step (103) if the extreme values ​​(91) at the pressure value pin c set working pressure p within the tolerance range (88) around the setpoint (87), whereby the working pressure p is successively adjusted and set to an optimized pressure value p opt is set at which the extreme values ​​(91) have a predetermined minimum deviation (89) from the target value (87) and remain within the tolerance range (88) around the target value (87); or a warning step (107) if at least one of the extreme values ​​(91) lies outside the tolerance range (88) around the target value (87) for the working pressure p set to the increased pressure value pinc.

2. Method according to claim 1, characterized in that the successive adjustment of the working pressure p in the optimization step (103) is carried out in that the working pressure p starting from the increased pressure value p^c until the optimized pressure value p opt is gradually reduced.

3. Method according to claim 1, characterized in that the optimization step (103) comprises the following sub-steps: successive reduction of the adjustable working pressure p starting from the increased pressure value pinc, until at least one of the extreme values ​​(91) lies outside the tolerance range (88) around the setpoint value (87), wherein during the successive reduction the time profile (90) of the actual value x is recorded and a minimum required pressure value p req is determined at which the actual values ​​x were last in the tolerance range (88) around the target value (87); Determining the minimum required pressure value p req than the optimized pressure value p opt or specifying the minimum required pressure value p req plus a specified safety margin as the optimized pressure value p op t.

4. Method according to one of claims 1 to 3, characterized in that the predetermined number of extreme values ​​is at least one and / or a maximum of 50.

5. Method according to one of claims 1 to 4, characterized in that the pressure adjustment process (100) comprises a pressure maximization step before the warning step (107) if the increased pressure value p^c is less than the maximum value p ma x, where the working pressure p is set to the maximum value p ma x is set, and that after the pressure maximization step, the optimization step (103) is carried out if the extreme values ​​(91) are within the tolerance range (88) around the target value (87), or the warning step (107) is carried out if at least one of the extreme values ​​(91) is outside the tolerance range (88) around the target value (87).

6. Method according to one of claims 1 to 5, characterized in that the pressure adjustment process (100) comprises a waiting step (105) before the warning step (107) if at least one of the extreme values ​​(91) at the working pressure p set to the increased pressure value pinc lies outside the tolerance range (88) around the setpoint value (87), wherein after expiry of a time window the optimization step (103) is carried out if the extreme values ​​(91) lie in the tolerance range (88) around the setpoint value (87), or the warning step (107) is carried out if at least one the extreme values ​​(91) are outside the tolerance range (88) around the target value (87).

7. Method according to one of claims 1 to 6, characterized in that the warning step (107) comprises at least one of the following sub-steps: - Output of an acoustic warning signal; - Issue a visual warning signal; Stopping the combing process of the combing machine (1).

8. Method according to one of claims 1 to 7, characterized in that the control and regulation unit (56) carries out a pressure reduction process if the predetermined number of extreme values ​​(91) has an actual deviation from the target value (87) which is smaller than the predetermined minimum deviation (89), or if the predetermined number of extreme values ​​(91) is smaller than a tolerance lower limit of the tolerance range (88), wherein in the pressure reduction process the adjustable working pressure p successively from the current pressure value p ac t is adjusted to a reduced pressure value pdec at which the extreme values ​​(91) have the specified minimum deviation (89) from the setpoint (87) and remain within the tolerance range (88) around the setpoint (87).

9. Method according to one of claims 1 to 8, characterized in that a sensor output signal of a sensor (54) assigned to the combing belt (3) represents the actual value x.

10. The method according to one of claims 1 to 9, characterized in that the tear-off devices (65) each comprise two of the tear-off roller pairs (30, 31), wherein a first tear-off roller pair (30) of the two tear-off roller pairs is arranged upstream of a second tear-off roller pair (31) of the two tear-off roller pairs in a strip travel direction (59), and in that the pressure supply system (78) has at least two of the pressure regulators (83) in order to apply a first adjustable working pressure to the actuating elements (74) assigned to the first tear-off roller pair (30) and a second adjustable working pressure to the actuating elements (75) assigned to the second tear-off roller pair (31), wherein the control and regulating unit (56) is configured to set the first working pressure higher than the second working pressure.

11. Combing machine (1) for producing a combing sliver (3), which (3) comprises a plurality of combing heads (2) for forming individual combing head slivers (29), each with a tear-off device (65) comprising at least one tear-off roller pair (30, 31) with a rotationally drivable tear-off roller (68, 70) and a counter-roller (69, 71), and at least one roller loading device (72, 73) having at least one actuating element (74, 75) associated with the counter-roller (69, 71); a pressure supply system (78) which is connected via pressure connections (79, 80) to the roller loading devices (72, 73) and comprises at least one pressure regulator (83) which is configured to supply at least a subset of the actuating elements (74, 75) with the pressure between a minimum value p m in and a maximum value p max adjustable working pressure p; a compression device (37) for combining the individual combing head bands (29) to form the combing band (3); a measuring device (55) for detecting an actual value x of a measured variable assigned to the combing band (3); and a control and regulating unit (56) which is configured to control the at least one pressure regulator (83) based on a recurring target-actual comparison between the actual value x and a predetermined target value (87) for setting the working pressure p, characterized in that the combing machine (1) is configured to carry out the method according to one of the preceding claims 1 to 10.

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