EP3794169B1 - Method for determining the drum fill level of a carding machine, and carding machine having an associated controller - Google Patents

Description

The present invention relates to a method for determining the drum loading on a carding machine and to a carding machine with an associated control system.

The term drum loading refers to the total fiber mass that is stationary and temporarily located on the drum or in the drum space of a card. It is known that production, sliver number, carding distance, speed of the rotating components, clothing selection, fiber material, fiber length and other components have an influence on the drum loading.

Particularly when textile fibers are changed quickly due to production changes, for example from cotton fibers to chemical fibers or mixtures of textile fibers, it is necessary to know the lag time with which the previous fibers are processed in the card. If the new card sliver is measured after a start-up phase that is too short when changing materials, quality losses can be detected, the cause of which lies in the drum being covered with the previous fibers.

The EP 1167591 A1 describes the possible influence of the transfer factor (doffer transient) on cards. This refers to the proportion of the fiber mass on the drum covering that is transferred to the doffer per drum revolution. This document suggests proposes to determine the nep count values and the fiber length distribution and to link them together in order to optimize production. The document does not provide any indication of how a control system optimizes the operating parameters based on this link, since the characteristic curves referred to here are not further defined. The transfer factor is to be qualitatively changed by adjusting the factors nep count, fiber length distribution and clothing spacing, without revealing how the transfer factor is precisely determined. According to this state of the art, the transfer factor and thus the fiber flow is to be controlled during operation by automatically adjusting the operating parameters.

The EP1215312 A1 discloses the determination of the transmission factor between two rollers by determining the fiber coverage of the interacting rollers using sensors.

The object of the invention is to provide a method with which the drum loading of a carding machine can be determined.

This object is achieved on the basis of a method according to the preamble of claim 1 with the respective characterizing features. Advantageous developments of the invention are specified in the dependent claims.

The invention includes the technical teaching that when determining the drum loading on a card, the supply of fibers into the card is stopped and at the same time all of the fibers in the drum space of the card are removed, whereby the sliver number and the delivery of the fibers (delivery path) at the card outlet are measured.

The core idea of the invention is to empty the entire drum space with fibres, some of which circulate around the rotating drum several times. This not only removes the fibres on the The fiber mass in the entire system is not only removed from the fibers in the material circulation path, but also from the fiber mass in the entire system before a quality measurement is carried out with a new fiber quality. This means that a card sliver that no longer contains any fibers from the previous batch only reaches the funnel after traveling a multiple of the delivery path covered via the material circulation path. Instead of the funnel, measuring rollers with sensors can also be used to convert the fleece into a fiber sliver and determine the mass flow.

In contrast to the current state of the art, the operation of the card must be interrupted in order to empty it of fibers and thus determine the current drum loading. This is a prerequisite so that a thin spot is created during operation or during ongoing production, from which the drum loading is determined. If the result of the drum loading measurement deviates from a reference value, the operator is informed of an incorrect setting and/or a worn-out clothing and/or a change in the fiber quality.

An advantageous development of the method provides that the supply of fibers to the card is interrupted by stopping or reducing the feed of a feed roller. The feed roller is at the beginning of the theoretical material circulation path of the fibers in the card. The end of the material circulation path is defined by the funnel or the measuring rollers at the exit of the card, where the sliver number and the delivery path are measured.

The time it takes for the fibers to travel along the material circulation path from the feed roller to the funnel or measuring rollers is defined as dead time. It can be determined for each card using the speed and the wrap angle of the fibers on the rotating components.

Another advantage is that the temporary drum occupancy can be determined by determining the dead time and the measured sliver number. This corresponds to the shortest delivery path in which the card sliver is pulled onto the funnel with a constant sliver number.

Advantageously, the total fiber mass in the drum chamber can be determined from the sum of the measured sliver number and the delivery route. With this knowledge, the cards can be adjusted in terms of quality assurance when changing fibers in such a way that incorrect measurements are avoided.

By determining the drum loading, it can be determined whether the card is correctly set up for production with the current fiber quality. The deviation from a reference value that is stored in the card control system for each fiber quality tells the card operator that the card is not correctly set up. The speed of the drum or the doffer may deviate from an optimum, so that if the speed is too high, the drum loading decreases.

If the carding gap is too large or the clothing is worn, the drum loading can increase or decrease. The wrong selection of clothing can also be represented by a deviation from the reference value. If the distance between the doffer and the drum is too great, the drum loading value deviates upwards or downwards from the reference value. When determining the drum loading and a deviation from the reference value, the control system automatically suggests the operator the optimal setting data, which is compared with the existing setting data. This excludes the possibility of incorrect setting data adding up to a correct reference value, but the quality of the carding sliver is poor.

The card according to the invention comprises a control system for determining the drum loading, whereby the control system is designed to compare the determined drum loading for each fiber quality with its own specific reference value and, in the event of deviations between the determined drum loading and the specific reference value, to give the operator information on how to optimize the card setting. A data storage device is connected to the control system, in which empirically determined values for the drum loading (reference values) are stored depending on the fiber quality with optimal setting values for the card.

Figur 1

eine Schnittdarstellung durch eine Karde;

Figur 2

ein zugehöriges Messdiagramm zur Ermittlung der Trommelbelegung in einer ersten Phase;

Figur 3

ein zugehöriges Messdiagramm zur Ermittlung der Trommelbelegung in einer zweiten Phase.

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. They show:

Figure 1

a cross-section through a carding machine;

Figure 2

an associated measurement diagram for determining the drum loading in a first phase;

Figure 3

an associated measurement diagram for determining the drum load in a second phase.

Fig. 1 shows a carding machine according to the state of the art, in which fiber flakes are guided via a shaft to a feed roller 1, a feed table 2, via several licker-in rollers 3a, 3b, 3c to the drum 4 or the tambour. On the drum 4, the fibers of the fiber flakes are parallelized and cleaned by means of fixed and rotating carding elements 20 arranged on a revolving cover. The resulting fiber web is then conveyed via a doffer 5, a doffer roller 6 and several squeezing rollers 7, 8 to a fleece guide element 9, which forms the fiber web with a funnel 10 into a fiber band, which is transferred via take-off rollers 11, 12 to a subsequent processing machine or a can 15. Instead of the funnel 10, measuring rollers (not shown) can also form the resulting fleece into a fiber band and determine the mass flow in the process.

In order to determine the drum loading, the total amount of fiber in the drum space must be determined. This is significantly more than the amount of fiber that is transported via the material circulation track 14, since the fibers are circulated several times around the drum 4 and rollers. 3a, 3b, 3c, 5, 6, 7, 8. The drum loading is made up of the stationary drum loading sTB and the temporary drum loading tTB. The temporary drum loading tTB refers to the fiber mass that is present on the active carding surface from the feed roller 1 to the doffer 5. The fibers are located in the area of the material circulation path 14 on the drum 4. This amount is relatively small and can, for example, be around 2.0 g for a drum 4 with a diameter of 1,300 mm and a working width of 1,280 mm with a sliver weight of 4.92 ktex.

The stationary drum loading sTB refers to the fiber mass that is stored in the clothing of the drum chamber and is not removed by the doffer 5. This fiber mass can circulate and be transported several times with the drum 4. The amount for the stationary drum loading sTB can be around 16 g for the same card dimensions and is therefore many times larger than the temporary drum loading tTB. In this approach, the waste separation, which is usually less than 5% of the fiber quantity, is neglected.

To determine the drum occupancy, the first step is to empty the entire drum chamber in the following order:
The feed roller 1 stops during production. Since the fibers are transported further via the drum 4 and the doffer 5, among other things, the fiber flow breaks off at the feed roller 1. At the same time as the feed roller 1 stops, a signal (CCD signal) is recorded at the funnel 10, which is used to determine the sliver break. The dead time within which the fibers can theoretically be separated from the Feed roller 1 to the funnel 10. The dead time defines the time that the fibers need to travel along the material circulation path 14 from the feed roller 1 to the funnel 10. It is therefore the shortest or ideal fiber circulation time between the feed roller 1 and the funnel 10. The dead time results from the speed and the wrap angle of the fibers on the respective component, for example the licker-in 3a, the drum 4 or the doffer 5.

Figure 2 shows a measurement diagram in which the delivery path in meters of the card sliver or the fibers in the card is entered on the abscissa. The sliver number in kilotex, which here is 5.49 ktex, is entered on the ordinate. The jagged curve is the connection of the individual measured values MW at funnel 10. When the measurement starts when the licker-in 1 stops feeding, the area under the curve gives the total fiber mass FM in the system. The left rectangular area indicates the sliver mass produced during the dead time, which runs along the material circulation path 14 to the funnel 10. In this embodiment, the sliver number remains relatively constant up to a delivery path of 4.7 m. This corresponds to the fiber mass that was produced within the dead time. The drop in the measurement curve shows that the remaining fiber mass in the carding area is being transported away, with the sliver at the funnel 10 becoming thinner and thinner and therefore the sliver number falling. In this example, the sliver number drops to about 1.5 ktex and ends at a delivery distance of about 14 m. The entire area under the measurement curve therefore shows the fiber mass FM in the carding room. If the fiber mass produced in the dead time (left rectangular area) is subtracted from this fiber mass FM in the carding room, the stationary drum loading is obtained. Determining the drum loading can be carried out at any time by interrupting operation of the carding machine.

In a second phase, the speed of the feed roller 1 is reduced during production so that a thin spot is deliberately created in the subsequent fiber sliver. Since the fibers are transported further via the drum 4 and the doffer 5, among other things, the fiber flow at the feed roller 1 is reduced. At the same time as the speed of the feed roller 1 is reduced, a signal (CCD signal) is recorded at the funnel 10, which is used to determine when the thin spot in the fiber sliver has been triggered. After a time of, for example, T = 1 second, the feed roller 1 is increased back up to the normal speed. The dead time within which the fibers are theoretically transported from the feed roller 1 to the funnel 10 can be determined using the recorded speeds of the licker-in 3a, 3b, 3c, drum 4, doffer 5 and the doffer rollers 11, 12. The dead time defines the time that the fibers need to travel along the material circulation path 14 from the feed roller 1 to the funnel 10. It is therefore the shortest or ideal fiber circulation time between the feed roller 1 and the funnel 10. The dead time results from the speed and the wrap angle of the fibers on the respective component, for example the licker-in 3a, the drum 4 or the doffer 5.

Figure 3 shows a measurement diagram in which the delivery path in meters of the card sliver or the fibers in the card is entered on the abscissa. The sliver number in kilotex is entered on the ordinate, which is 5.49 ktex here. The jagged curve is again the connection of the individual measured values MW, which are determined at the funnel 10. When the measurement starts when the speed of the feed roller 1 is reduced, the area under the curve gives the total fiber mass FM in the system. The left rectangular area gives the fiber mass FM during the dead time. produced sliver mass, which runs along the material circulation path 14 to the funnel 10. In this embodiment, the sliver number remains relatively constant up to a delivery path of 4.7 m. This corresponds to the fiber mass that was produced within the dead time. The drop in the measurement curve shows that the remaining fiber mass in the carding area is being transported away, whereby the fiber sliver at the funnel 10 becomes thinner and thinner and therefore the sliver number drops. After, for example, the time T = 1 s, the speed of the feed roller 1 is accelerated again to the normal operating value, so that the curve with the measured values MW slowly rises again until the normal amount of fiber fed in is once again constantly reached at approx. 5.49 ktex. The decreased curve with the measured values MW is the basis at this time T for determining a curve with simulated measured values sMW based on the values for drum loading determined by the card manufacturer (phase 1). This curve also decreases with the sliver number to around 1.5 ktex and ends at a delivery distance of around 14 m. The entire area under the measurement curve therefore shows the fiber mass FM in the carding room. The area under the simulated measurement curve sMW then shows the fiber mass FM in the carding room when production is interrupted. If the fiber mass produced during the idle time (left rectangular area) is deducted from this simulated fiber mass FM in the carding room, the stationary drum loading is obtained without the card operator having to interrupt production. This second determination of the drum loading is based on the findings and data obtained from determining the drum loading during the first phase.

Tests on drum loading with different band numbers and varying production show that the drum loading is proportional increases with increasing production. It has also been shown that the drum load increases proportionally with increasing sliver number. The drum load also increases with increasing fiber length (comparison PIMA to DENIM).

This means that when the fiber quality changes, a multiple of the sliver mass produced during the dead time must be removed from the drum chamber before the new sliver can be qualitatively examined.

The card also has a control system in which reference values for the drum loading for different fiber qualities are stored using a data memory. These reference values include specified setting values for carding operation, such as at least the speed of the drum 4 and the doffer 5, the associated clothing and the size of the carding gap, as well as the distance of the doffer 5 from the drum 4.

By determining the drum loading, it can be determined whether the card is correctly set up for production with the current fiber quality. If there are deviations from the reference value, the operator is shown possible causes so that he can check the card settings. If the reference value of the drum loading was reached in a first measurement with the recommended settings, but not in a second measurement after about a week of operation, the cause may be an adjustment of the card operating parameters due to temperature changes or clothing wear. The control system suggests a solution to the operator based on stored empirical data, for example adjusting the carding gap, checking the clothing or checking the distance from the doffer 5 to the drum 4.

If the carding gap is too large or the clothing is worn, the drum loading can increase or decrease. The wrong selection of clothing can also be represented by a deviation from the reference value. If the distance between the doffer and the drum is too great, the drum loading value deviates upwards or downwards from the reference value. When determining the drum loading and a deviation from the reference value, the control system automatically suggests the operator the optimal setting data, which is compared with the existing setting data. This excludes the possibility of incorrect setting data adding up to a correct reference value, but the quality of the carding sliver is poor.

Example:

A card is set to produce 80 kg/h of PIMA quality cotton. The delivery speed of the card sliver produced is 271 m/min at 4.92 ktex. Drum 4 is operated at 500 rpm and doffer 5 at 64 rpm. The reference value of the drum loading is 17.9 g with a total fiber mass of 36.3 g in the drum space. The measurement shows a temporary drum loading tTB of 2 g and a stationary drum loading of 15.9 g, so that the total drum loading without deduction of waste is 17.9 g.

If a higher drum loading is determined during a subsequent measurement, this may be an indication of an enlarged carding gap and the control system suggests an adjustment of the carding gap to the operator or can determine this independently using sensors and adjust it using actuators.

If a subsequent measurement shows a smaller drum loading, this may be an indication of a change in the fed fiber length or an increase in the drum speed.

The invention is not limited in its implementation to the preferred embodiment given above.

reference sign

1

feed roller

2

dining table

3a, 3b, 3c

licker-a-thumb

4

drum

5

customer

6

pickup roller

7

squeezing roller

8

squeezing roller

9

fleece guide element

10

funnel

11

take-off roller

12

take-off roller

13

carding element

14

material circulation path

15

pot

16

roller

17

revolving lid

20

carding element

FM

total fiber mass in the drum chamber

MW

measured values

sMW

simulated measured values

sTB

stationary drum loading

tTB

temporary drum occupancy

T

Time of reduced speed of the feed roller

Claims (8)

1. A method for determining the drum occupancy on a card, which results from the total fibre mass which is stationary and temporarily on the drum (4) or in the drum space of the card, characterised in that the supply of fibres into the card is stopped for the first time in an initial phase and at the same time the total fibres present in the drum space of the card are withdrawn, wherein the sliver number and the delivery lenght of the fibres at the card output are measured and the drum occupancy is thus determined, and subsequently, in a second phase during operation of the card, the supply of fibres to the card is reduced for the time (T), wherein the sliver number and the delivery lenght of the fibres are measured at the card output, and based on the measured values (MW) determined at the time (T), a further curve, which corresponds to the withdrawal of the total fibres located in the drum space, is simulated by calculation based on the values (MW) determined during the initial phase for the drum occupancy.
2. A method according to claim 1, characterised in that the supply of fibres into the card is discontinued by stopping a feed roller (1).
3. A method according to claim 1, characterised in that a targeted thin section is generated in the produced fibre band by reduced delivery of a feed roller (1).
4. A method according to claim 1, characterised in that the sliver number and the delivery lenght to a funnel (10) or measuring rollers are determined.
5. A method according to claim 1, characterised in that it determines the delay time of the fibres in which the fibres are transported via a material orbit (14) from the feed roller (1) to the funnel (10).
6. A method according to one of the preceding claims, characterised in that the temporary drum occupancy (tTB) can be determined by mass balance and the determined sliver number.
7. A method according to one of the preceding claims, characterised in that the total fibre mass located in the drum space is determinable from the sum of the determined sliver number and the supply lenght .
8. Card, including a control for determining the drum occupancy according to one of claims 1 to 7, wherein the control is designed to compare the determined drum occupancy for each fibre quality with a specific reference value and, in the event of deviations between the determined drum occupancy and the specific reference value, to provide the operator with instructions to optimise the card setting and/or to optimise the setting, at least in part independently, by means of sensors and actuators.

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