METHOD FOR DETERMINING THE DRUM OCCUPANCY ON A CARD AND CARD WITH AN ASSOCIATE CONTROL SYSTEM

Description

[0001] 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.

[0002] The term "drum loading" refers to the total fiber mass that is located both stationary and temporarily on the drum or in the drum chamber of a carding machine. It is known that production, sliver count, carding distance, speed of rotating components, clothing selection, fiber material, fiber length, and other components influence the drum loading.

[0003] Especially when changing textile fibers quickly due to production changes, for example, from cotton fibers to chemical fibers or blends of textile fibers, it is essential to know the lag time of the existing fibers being processed in the card. If the new card sliver is measured after a start-up phase that is too short during a material change, quality degradation may be detected, the cause of which lies in the drum loading with the existing fibers.

[0004] EP 1167591 A1 describes the potential influence of the doffer transient on cards. This refers to the proportion of fiber mass on the drum lining that is transferred to the doffer per drum revolution. This document proposes determining and linking the nep count values ​​and the fiber length distribution to optimize production. The document provides no indication of how a control system optimizes the operating parameters based on this link, as the characteristic curves referred to here are not further defined. The doffer transient is intended to be qualitatively changed by adjusting the nep count, fiber length distribution, and clothing spacing factors, without disclosing how the doffer transient is precisely determined. According to this state of the art, the doffer transient, and thus the fiber flow, is to be controlled during operation by automatically adjusting the operating parameters.

[0005] EP1215312 A1 discloses the determination of the transmission factor between two rollers by determining the fiber coverage of the interacting rollers using sensors.

[0006] The object of the invention is to provide a method by which the drum loading of a carding machine can be determined.

[0007] This object is achieved by 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.

[0008] The invention includes the technical teaching that when determining the drum loading on a card, the feed of fibers into the card is stopped and at the same time all the fibers located 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.

[0009] The core concept of the invention is the emptying of the entire drum chamber with fibers, some of which revolve around the rotating drum several times. This removes not only the fibers on the material circulation path, but also the fiber mass present in the entire system before a quality measurement is performed with a new fiber quality. As a result, a carded sliver that no longer contains any fibers from the previous batch loading only reaches the hopper after traveling a distance many times the distance traveled via the material circulation path. Instead of the hopper, measuring rollers with sensors can also be used to convert the web into a fiber sliver and determine the mass flow.

[0010] In contrast to the current technology, carding operation must be interrupted to allow it to run clear of fibers and thus determine the current drum loading. This is necessary to create a thin spot during operation or ongoing production, from which the drum loading is determined. If the drum loading measurement result deviates from a reference value, the operator receives an indication of an incorrect setting and / or worn clothing and / or a change in fiber quality.

[0011] An advantageous development of the method provides for the fiber feed into the carding machine to be interrupted by stopping or reducing the feed rate of a feed roller. The feed roller is located at the beginning of the theoretical fiber circulation path in the carding machine. The end of the material circulation path is defined by the hopper or the measuring rollers at the carding machine exit, where the sliver number and the delivery path are measured.

[0012] The time it takes for the fibers to travel along the material orbit from the feed roller to the funnel or measuring rollers is defined as dead time. It can be determined for each card using the rotational speed and the wrap angle of the fibers on the rotating components.

[0013] Another advantage is that the temporary drum loading can be determined by determining the dead time and the measured sliver number. This corresponds to the shortest delivery path at which the card sliver is pulled onto the hopper with a constant sliver number.

[0014] Advantageously, the total fiber mass in the drum chamber can be determined from the sum of the measured sliver number and the delivery path. This information allows the carding machines to be adjusted for quality assurance purposes during a fiber change to avoid incorrect measurements.

[0015] By determining the drum loading, it can be determined whether the card is correctly adjusted for production at the current fiber quality. A deviation from a reference value stored in the card control system for each fiber quality indicates to the card operator that the card is not correctly adjusted. The speed of the drum or doffer may deviate from an optimum, so that if the speed is too high, the drum loading decreases.

[0016] If the carding gap is too large or the carding clothing is worn, the drum loading can increase or decrease. Incorrect carding clothing selection can also be indicated 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 optimal setting data to the operator, which is then compared with the existing setting data. This eliminates the possibility of incorrect setting data adding up to a correct reference value, but the quality of the carded sliver is poor.

[0017] The carding machine according to the invention comprises a control system for determining the drum loading. 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 provide the operator with information on how to optimize the carding machine settings. A data memory is connected to the control system, in which empirically determined values ​​for the drum loading (reference values) are stored as a function of the fiber quality, along with optimal carding settings.

[0018] 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 shows a sectional view of a carding machine; Figure 2 shows a corresponding measurement diagram for determining the drum loading in a first phase; Figure 3 shows a corresponding measurement diagram for determining the drum loading in a second phase.

[0019] Fig. 1shows a prior art carding machine 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 reel tambour. On the drum 4, the fibers of the fiber flakes are parallelized and cleaned by means of fixed carding elements 20 arranged on a revolving flat and rotating. The resulting fiber web is then conveyed via a doffer 5, a doffer roller 6 and several squeeze rollers 7, 8 to a web guide element 9, which forms the fiber web into a fiber sliver with a hopper 10, which is transferred via take-off rollers 11, 12 to a downstream processing machine or a can 15. Instead of the hopper 10, measuring rollers (not shown) can also form the resulting web into a fiber sliver and determine the mass flow rate.

[0020] 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 transported via the material circulation path 14, since the fibers are transported multiple 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 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 approximately 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.

[0021] The stationary drum loading sTB refers to the fiber mass that is stored, among other things, in the clothings 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 of the stationary drum loading sTB can be approximately 16 g for the same card dimensions and is thus many times greater than the temporary drum loading tTB. This approach neglects the waste removal, which typically amounts to less than 5% of the fiber quantity.

[0022] To determine the drum occupancy, the entire drum space is emptied in the following sequence in a first phase: Feed roller 1 stops during production. Since the fibers are transported further via drum 4 and doffer 5, among other things, the fiber flow breaks at feed roller 1. Simultaneously with the stop of feed roller 1, a signal (CCD signal) is recorded at hopper 10 to detect the sliver break. The dead time within which the fibers are theoretically transported from feed roller 1 to hopper 10 can be determined using the recorded speeds of licker-in 3a, 3b, 3c, drum 4, doffer 5, and up to doffer rollers 11, 12. The dead time defines the time the fibers require to travel along the material circulation path 14 from feed roller 1 to hopper 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.

[0023] Figure 2shows a measurement diagram in which the delivery distance of the carded sliver or fibers in the card is plotted in meters on the abscissa. The sliver count in kilotex, which in this case is 5.49 ktex, is entered on the ordinate. The jagged curve is the connection between 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-hand 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 exemplary embodiment, the sliver count remains relatively constant up to a delivery distance of 4.7 m. This corresponds to the fiber mass that was produced during the dead time. The downward trend in the measurement curve shows that the remaining fiber mass in the carding area is being transported away, with the fiber sliver at the funnel 10 becoming increasingly thinner and therefore the sliver count decreases.In this example, the sliver count drops to approximately 1.5 ktex and ends at a delivery distance of approximately 14 m. The entire area below the measurement curve thus represents the fiber mass FM in the carding area. Subtracting the fiber mass produced during the dead time (left rectangular area) from this fiber mass FM in the carding area results in the stationary drum loading. The drum loading can be determined at any time by interrupting operation of the carding machine.

[0024] In a second phase, the speed of feed roller 1 is reduced during production so that a thin spot is deliberately created in the subsequently produced fiber sliver. Since the fibers are transported further via drum 4 and doffer 5, among other things, the fiber flow at feed roller 1 is reduced. Simultaneously with the speed reduction of feed roller 1, a signal (CCD signal) is recorded at funnel 10, which detects the triggering of the thin spot in the fiber sliver. After a time of, for example, T = 1 second, feed roller 1 is increased back to its normal speed. The dead time within which the fibers are theoretically transported from feed roller 1 to funnel 10 can be determined using the recorded speeds of licker-in 3a, 3b, 3c, drum 4, doffer 5 and doffer rollers 11, 12.The dead time defines the time required for the fibers to travel along the material circulation path 14 from the feed roller 1 to the funnel 10. It is thus the shortest or ideal fiber circulation time between the feed roller 1 and the funnel 10. The dead time results from the rotational 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.

[0025] Figure 3shows a measurement diagram in which the delivery distance in meters of the carded sliver or fibers in the card is plotted on the abscissa. The sliver number in kilotex, which in this case is 5.49 ktex, is entered on the ordinate. The jagged curve is again the connection between 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-hand 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 exemplary embodiment, the sliver number remains relatively constant up to a delivery distance of 4.7 m. This corresponds to the fiber mass that was produced within the dead time.The downward trend in the measured curve shows that the remaining fiber mass in the carding chamber is being transported away, with the fiber sliver at the funnel 10 becoming increasingly thinner and therefore decreasing in sliver count. After a time T = 1 s, for example, the speed of feed roller 1 is accelerated back to the normal operating value, so that the curve with the measured values ​​MW slowly increases again until the normal fed-in fiber quantity of approximately 5.49 ktex is constantly reached again. The downward trend in the curve with the measured values ​​MW forms the basis at this time T for determining a curve with simulated measured values ​​sMW based on the values ​​for drum loading (phase 1) determined by the card manufacturer. This curve also decreases with the sliver count to approximately 1.5 ktex and ends at a delivery distance of approximately 14 m. The entire area beneath the measured curve therefore shows the fiber mass FM in the carding chamber.The area below the simulated measurement curve sMW then shows the fiber mass FM in the carding area during a production interruption. Subtracting the fiber mass produced during the idle time (left rectangular area) from this simulated fiber mass FM in the carding area results in the stationary drum loading without the carding operator having to interrupt production. This second determination of the drum loading is based on the findings and data obtained from the drum loading determination during the first phase.

[0026] Drum loading tests with different sliver counts and varying production levels show that drum loading increases proportionally with increasing production. Furthermore, it has been shown that drum loading increases proportionally with increasing sliver count. Drum loading also increases with increasing fiber length (comparing PIMA to DENIM).

[0027] 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 space before the new sliver can be qualitatively examined.

[0028] The carding machine also features a control system in which reference values ​​for the drum loading for different fiber qualities are stored via a data memory. These reference values ​​include predefined settings for carding operation, such as at least the speed of drum 4 and doffer 5, the associated clothings and the size of the carding gap, as well as the distance of doffer 5 from drum 4.

[0029] By determining the drum loading, it can be determined whether the card is correctly set up for production with the current fiber quality. In the event of deviations from the reference value, possible causes are displayed to the operator so that they can check the card settings. If the reference value of the drum loading was reached in an initial measurement with the recommended settings, but not in a second measurement after approximately one week of operation, the cause may be an adjustment of the card operating parameters due to temperature changes or clothing wear. Based on stored empirical data, the control system suggests a solution to the operator, for example adjusting the carding gap, checking the clothing or checking the distance between doffer 5 and drum 4.

[0030] If the carding gap is too large or the carding clothing is worn, the drum loading can increase or decrease. Incorrect carding clothing selection can also be indicated 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 optimal setting data to the operator, which is then compared with the existing setting data. This eliminates the possibility of incorrect setting data adding up to a correct reference value, but the quality of the carded sliver is poor. Example:

[0031] A carding machine is set to produce 80 kg / h of PIMA cotton. The delivery speed of the produced carded sliver is 271 m / min at 4.92 ktex. Drum 4 operates at 500 rpm, and doffer 5 at 64 rpm. The reference value for the drum loading is 17.9 g with a total fiber mass of 36.3 g in the drum space. The measurement results in a temporary drum loading (tTB) of 2 g and a stationary drum loading of 15.9 g, so the total drum loading without deduction of waste is 17.9 g.

[0032] 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 it independently using sensors and adjust it using actuators.

[0033] 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.

[0034] The invention is not limited in its implementation to the preferred embodiment given above. Reference symbol

[0035] 1feed roller 2feed table 3a, 3b, 3clicker-in 4drum 5 take-off 6 take-off 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 15 can 16 roller 17 moving lid 20 carding element FMtotal fiber mass in the drum chamber MWmeasured values ​​sMWsimulated measured values ​​sTBstationary drum loading tTBtemporary drum loading Ttime of reduced speed of the feed roller

Claims

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.