WO2021165017A1

WO2021165017A1 - Method for producing a sliver, and carding machine

Info

Publication number: WO2021165017A1
Application number: PCT/EP2021/052091
Authority: WO
Inventors: Maximilian Marx; Christian KRÜTTGEN
Original assignee: TRüTZSCHLER GMBH & CO. KG
Priority date: 2020-02-20
Filing date: 2021-01-29
Publication date: 2021-08-26
Also published as: CN115151688B; DE102020104475A1; CN115151688A; EP4107319A1

Abstract

The invention relates to a method for controlling a carding machine (100) and to a carding machine (100), comprising: at least one feed roller (1) and a doffer (5) which each have separate controllable drives, wherein the carding machine (100) is designed to produce a sliver, which can be deposited in cans (15), from fibre flocks or a cotton stock, wherein, to exchange cans, the circumferential speed of the feed roller (1) is changed and the circumferential speed of the doffer (5) is subsequently changed with a time delay (Δts; Δte); a sensor (S2) which is designed to measure the mass of the sliver produced or the change in mass of the sliver produced, wherein, during each can exchange, a controller (20) of the carding machine determines the standard deviation (Ss2) of the change in mass (Δm) of the sliver based on the signal from the sensor (S2) and assigns a mean value (Ms2) to this standard deviation, wherein the controller (20) is designed to optimise the time delay (Δts; Δte) by means of at least two mean values (Ms2).

Description

Title: Method for producing a sliver and card

description

The invention relates to a method for producing a sliver and a card according to the preamble of claims 1 and 10.

At high production speeds in the manufacture of fiber slivers on the card, production must be shut down every time the can is changed, which has a negative effect on the quality of the sliver for subsequent processing. During card production in the acceleration or deceleration phase, the sliver weight should follow its target value. In the event of an impending can change with reduced production of the sliver, the feed roller speed of the card is changed, which is followed with a time delay by the lowering of the speed or peripheral speed of the customer. The time delay between the decrease in the feed roll speed and the decrease in the speed of the doffer is determined, among other things, by the fiber quality (material, fiber size, etc.) and the drum occupancy of the card. Since this time delay is decisive for the change in the sliver weight, which affects thin or thick places in the sliver and thus a deviation from the target value, this time delay is stored in the card controller using empirical values. This time delay must also be taken into account again when the card is started up after the can change has taken place.

EP 0799915 B2 describes the sliver regulation on a card during the deceleration and acceleration phase when changing cans. The document claims the use of a control algorithm with an integral component from the braking / acceleration ramp over a time interval, without disclosing the details of how these values influence the time delay.

Based on this prior art, the object of the invention is to optimize the time delay between lowering or increasing the feed roll speed and lowering or increasing the speed of the doffer so as to produce a card sliver that is as uniform as possible during the can change. The invention solves the problem posed by a method with the features specified in claim 1, and by a card according to claim 10. Advantageous further developments of the invention are defined in the dependent claims.

The invention relates to a method for controlling a card with at least one feed roller and a doffer, each of which has separate controllable drives, the card being designed to produce a sliver from fiber flocks or a lap which can be deposited in cans, the peripheral speed for changing cans the feed roller is changed and with a time delay (Ats; Ate) the circumferential speed of the customer is subsequently changed. For this purpose, the card has a sensor which is designed to determine the mass of the sliver produced or the change in mass of the sliver produced. A control of the card determines the standard deviation of the mass change of the sliver from the signal of the sensor with each can change and assigns a mean value to this. The control is designed to optimize the time delay between the change in speed of the feed roller and the change in speed of the customer by means of at least two mean values.

With the method according to the invention, the card can optimize the time delay between the reduction in the peripheral speed of the feed roller and the doffer itself, regardless of the fiber quality and the operating conditions. Apart from any start value, no fiber-related data need to be stored in the control. When changing a batch or a new fiber mixture, the control automatically determines the optimal time delay, by means of which the sliver number or mass deviation from the target value is optimized during the can change. The quality of the sliver is more uniform, which improves subsequent processing in the drafting system and / or in the air-jet spinning machine. Because the peripheral speed of the feed roller is reduced before the can change and the peripheral speed of the doffer is reduced with a time delay, the increase or decrease in the sliver number or the increase or decrease in mass of the sliver can be reduced to the setpoint at the beginning of the can change. Because the circumferential speed of the feed roller is increased at the end of the can change and the circumferential speed of the customer is increased with a time delay, the decrease or increase in the sliver number or the decrease or increase in mass of the sliver can be reduced to the target value at the end of the can change. The change in the circumferential speed of the feed roller and of the doffer can preferably take place with the same or different acceleration or deceleration. In the case of low drum occupancy, the controlled system between the sensors on the feed table and the strip take-off unit is reduced, so that the peripheral speed of the feed roll and the customer is changed with the same deceleration or acceleration. In the case of a high drum load, there is a large controlled system, so that when the fiber supply is reduced during the can change, the fibers from the drum load are passed on to the customer. At the end of the can change, it can make sense to accelerate the doffer to the nominal speed and thus to the nominal value of the peripheral speed.

The time delay at the start of the can change can preferably be the same or not the same as the time delay at the end of the can change. Here, too, the size of the drum occupancy must be taken into account in the controlled system between the sensors on the dining table and the belt removal. With a high drum load, the time delay to the start of the can change and the time delay to the end of the can change can be different. In the case of a low drum occupancy, the controlled system is shorter and the coordination between the speed change of the feed roller and doffer must be more precise, since there is less fiber mass in the card to compensate for fluctuations.

In a preferred embodiment, the control is designed to interpolate a minimum from a plurality of mean values (at least two mean values), which minimum forms the optimum time delay between the change in speed of the feed roller and the doffer. With the optimal time delay, the change in mass of the sliver (sliver number) from the target value during the can change can be reduced to a minimum. Two mean values are already sufficient for the control to start optimizing the time delay. With at least three mean values, the control is designed to interpolate a curve using the mean values, the minimum of which can represent the optimal time delay.

At the beginning of the first can change, the time delay is preferably specified by at least one value that can be stored in the controller. This value can be specified empirically and depend on the type of card, the clothing used, the fiber quality and the production conditions. Among other things, the drum occupancy and thus part of the controlled system also depend on these factors.

In a preferred embodiment, the control of the card is designed to control all drives of the card individually and at least the determined fiber mass on the sensor of the To process the feed trough with the determined mass of the sliver on the sensor and to regulate the associated drives. The control system can preferably store that the optimization of the time delay between the speed change of the feed roller and the doffer only occurs when the roller speed difference is, for example, at least 80 m / min and / or only when the ratio of the delivery speed of the strip when changing cans to the normal delivery speed of for example at least 80% starts. The limit values themselves, from which the process is to be used, can vary depending on the card type, the clothing used, the fiber quality and the production conditions and are intended to prevent the quality of the sliver from being over-regulated, as the carding gap control or other factors also affect the sliver number or sliver . Influence the change in mass of the sliver when changing cans.

The card according to the invention has at least one feed roller and a doffer, each of which has separate controllable drives, with a sensor that is designed to determine the mass of the fibers or wad entering the card, with a sensor that is designed to determine the mass of the sliver produced or the change in mass of the sliver produced, with a controller which is designed to carry out the method for operating the card according to one of the preceding claims.

Further measures improving the invention are shown in more detail below together with the description of a preferred exemplary embodiment of the invention with reference to the figures.

Show it:

Fig. 1 is a schematic side view of a card with the inventive

Contraption;

2 shows a schematic representation of the card with the drives and sensors relevant to the invention;

3 shows a diagram of the time delay when changing cans with the associated speeds of the feed roller and the doffer;

Fig. 4 is a diagram of the mass change of the sliver during the

Can change;

5 shows a schematic measurement diagram for the absolute change in mass during the can change;

6 shows a diagram to show the determined mean value with the associated time delay between the feed roller and the doffer.

Below, with reference to FIGS. 1 to 6, preferred embodiments of a device according to the invention and the method are explained, which is intended for use on a card for cotton, chemical fibers or the like. The same features in the drawing are each provided with the same reference symbols. At this point it goes without saying that the drawing is only shown in a simplified manner and, in particular, without a scale.

Fig. 1 shows a card 100 according to the prior art, in which fiber flocks are guided via a chute to a feed roller 1, a feed table 2, via one or more lickerins 3a, 3b, 3c, to the drum 4 or the tambour. On the drum 4, the fibers of the fiber flocks are parallelized and cleaned by means of fixed carding elements 20, suction hoods and separating knives and by means of revolving carding elements 14 arranged on a revolving cover system 17. The resulting fiber web is then conveyed via a pick-up 5, a stripping roller 6 and several nip rollers 7, 8 to a fleece guide element 9, which transforms the fiber web with a funnel 10 into a fiber band, which is sent via take-off rollers 11, 12 to a subsequent processing machine or a can 15 hands over. The adjustment of the carding elements 14 to the drum 4 (carding gap) takes place via slide strips, not shown, which have elements which are aligned in a wedge-shaped manner with respect to one another.

In FIG. 2, only the drives and sensors that are essential for the invention are shown, which make up only a part of all the drives and sensors that are present. The feed roller 1 is driven by the drive M1. In the area of the feed roller 1 on the feed trough (not shown in more detail), the sensor S1 is arranged, with which the quantity or mass of the incoming lap sample is detected. The sensor S1 can be designed, for example, as a capacitive or inductive sensor which detects the deflection of a sensor and thus indirectly determines the mass flow rate of the wadding. The feed roller 1 is driven by the drive M1 at a speed of up to 40 rpm. The drive M4 drives the drum 4, which is driven at a constant speed of for example 1500 rpm during the acceleration or deceleration phase of the can change. The pick-up 5 is driven by the drive M5 at, for example, 300 rpm. After the doffer 5, the fiber pile is formed into a fiber tape by means of a transverse sliver and pile funnel 10 (not shown), with a further sensor S2 being arranged on or after the pile funnel 10, with which the mass of the fiber tape can be determined directly, indirectly, or the deviation from a target value is. The sensor S2 can also be designed as a capacitive or inductive sensor which determines the mass flow rate or the change in the mass flow rate of the sliver by means of a deflection of a sensor or between two disks that are matched to one another. All of the drives M1, M4, M5 shown can be designed as servomotors or frequency-controlled drives that are activated and regulated by the controller 20. The data from the sensors S1, S2 also enter the controller 20 and are subsequently evaluated there. The controller 20 uses the determined mass flow rate of the sensor S2 to calculate the can filling time and the point in time tk of the can change. The speed of the feed roller 1 is reduced with a lead time before the can change, which is followed by the speed reduction or reduction of the peripheral speed of the doffer 5 with a time delay Ats.

The controlled system in this system is determined by the running time of the fibers in the card 100, that is, from a change in the speed of the feed roller 1 to the detection of the changed fiber mass at the sensor S2. Since, due to the drum occupancy, the fibers can be transported several times around the drum 4 before they are transferred to the doffer 5, the controlled system can be larger than the direct transport path over the respective drum circumference. The delivery speed of the buyer 5 is reduced with each can change. Since the drum 4 continues to run at a constant speed, the mass of the sliver on the can deposit increases, which leads to undesirable thick spots. Once the can has been changed, the speed of the doffer 5 increases, as a result of which the fiber mass delivered per unit of time decreases, since the drum 4 continues to run at a constant speed. For this purpose, the controller 20 provides, before the can change, to reduce the speed or circumferential speed of the feed roller 1 in order to convey a smaller fiber mass into the card. Simultaneously with the can change and the reduction in the delivery speed of the sliver, the speed of the doffer 5 is reduced, which first of all leads to an increase in the mass in the sliver. The time delay between the lowering of the speed of the feed roller 1 and the lowering of the speed of the pickup 5 is determined by determining the weight of the strip at this point in time. The standard deviation Ss2 to the nominal value of the sliver mass is determined from this signal of the sliver mass during the can change. The mean value Ms2 is formed from this standard deviation Ss2. Starting from a starting value of the time delay Ats of 0.7 s, for example, this process is repeated with each can change with a reduced or increased value of the time delay Ats until a new mean value Ms2 is determined for each can change. A curve can be interpolated from the mean values Ms2, from the minimum of which the optimum time for determining the time delay Ats between the start of the reduction in the speed of the feed roller 1 and the start of the reduction in the speed of the pickup 5 is determined. Two mean values Ms2 are sufficient for the control to increase or decrease the time delay Ats. The optimal time delay is assumed to be the value at which the sliver mass exhibits the smallest deviation from the nominal value. The standard deviation Ss2 and the mean value Ms2 to be determined therefrom can be different for each fiber quality. The invention thus has the advantage that, apart from a first starting value, no empirical data need to be recorded. The first starting value for the time delay for starting the can change Ats can be, for example, 0.7 seconds and depends on the one hand on the controlled system and the drum occupancy. Depending on the type of card and the fiber quality to be processed, the start value for the time delay can also be just 0.4 seconds. The card 100 automatically optimizes the time delay between the speed reduction of the feed roller 1 and the doffer 5, so that the customer can operate the card 100 with different fiber qualities and different operating conditions (production volume, ambient temperature, humidity of the fibers). For example, the time delay at the start of the can change Ats can be reduced to 0.55 seconds, as a result of which the mass defects in the sliver are reduced to a minimum. FIG. 3 shows a diagram in which the time t in seconds is plotted on the abscissa. The ordinate shows the speed v in m / min, to which an associated speed n in rpm of the feed roller 1 and the doffer 5 is assigned. The curve with the continuous line shows the speed profile of the feed roller 1, the speed or the rotational speed being reduced with a lead before the time tk of the can change. The time tk is the start of the can change and thus at the same time the time of the speed reduction of the feed roller 1. When the remaining amount in meters of the sliver that is to be filled into the current can falls below a limit value, the can change is initiated. For this purpose, the speed or rotational speed of the feed roller 1 is reduced. With the time difference Ats for reducing the speed of the feed roller 1, the speed of the doffer 5 (dashed line) is reduced. When both rollers 1, 5 have reached their can changing speed or the associated speed, the actual can change is carried out after synchronization with the depositing plate. Before the end of the can change, the rotational speed or peripheral speed of the feed roller 1 is increased again with a time lead, which is followed by the rotational speed or peripheral speed of the doffer 5 with a time delay of Ate. In this illustration, the speed n and the speed v on the ordinate of feed roller 1 and doffer 5 are proportional to one another. Due to the delay within the card 100 at the transition points between the rollers and the fine resolution of the fibers to form a fiber web, the doffer 5 is operated at a higher circumferential speed than the feed roller 1. The same acceleration or deceleration of the circumferential speed of feed roller 1 is achieved and customer 5 assumed.

FIG. 4 also shows the time t on the abscissa and the change in mass Am of the sliver from the desired value, which is entered with 0, on the ordinate. Corresponding to the reduction in speed of the doffer 5 with the can change at time tk, the mass of the sliver increases and decreases again until it is regulated to the desired value. When the speed of the doffer 5 is increased, the mass of the sliver first drops below the setpoint value until it is regulated out again. FIG. 4 shows the course of the strip for too little or no time delay Ats, Ate between the speed difference of feed roller 1 and doffer. If the time delay Ats, Ate is too great, the signal behavior changes and first a thin point and then a thick point is generated in the sliver. The arrows on the measurement curves indicate the direction of the optimization of the time delay Ats, Ate between the speed reduction of the feed roller 1 and the speed reduction of the collector 5. The deviations from the nominal value shown in FIG. 4 can be smaller with each can change. FIG. 5 again shows the time t on the abscissa, and the speed v in m / min of the feed roller 1 and of the doffer 5 on the left ordinate. Their speeds n in rpm are proportional to the speed of the rollers. The curve of the feed roller 1 is shown again as a continuous line, and the curve of the doffer 5 as a dashed line. On the right ordinate, the absolute mass ms2 of the sliver at the sensor S2 of the sliver take-off is indicated in ktex. The increase in mass of the sliver is almost not visible on the diagram with the decrease in the doffing speed. From the fluctuating sliver mass ms2 recognizable in this diagram, the controller 20 calculates the standard deviation Ss2 of the sliver mass and forms a mean value MS2 therefrom. With each can change, a new standard deviation Ss2 with a new mean value Ms2 is determined, the control system storing the mean values Ms2 and using the stored mean values Ms2 to interpolate a curve from three mean values Ms2, the minimum of which is the optimum for these operating conditions (productivity of the card, fiber quality) Time delay to the start and to the end of the can change in the speed reduction of feed roller 1 and doffer 5 represents. Two mean values Ms2 are already sufficient for the control to recognize the direction of the time delay between the speed reduction of the feed roller 1 and the doffer 5. Since this is an ongoing process, the time delay Ats and Ate is already optimized with the second can change, since the controller can derive a first optimization for the smallest possible deviation of the sliver mass from the setpoint from two stored mean values Ms2. Advantageously, the time delay Ats and Ate can be different for the first can change, so that the control can optimize the time delay from the mass deviation of the sliver from the target value. During the first can change, two mean values Ms2 can therefore be formed from the time delay Ats and Ate at the beginning and at the end of the can change, so that the second can change already takes place with an optimized time delay and an improved deviation of the sliver mass from the target value.

In the exemplary embodiment in FIG. 6, the time delay Δt over which several can changes have taken place is displayed on the abscissa. The mean values are on the ordinate

MS2 of the standard deviations Ss2 entered in percent. In the diagram are for each

Can change a new mean value Ms2-1 to Ms2-n entered with an associated

Time delay Ats / Ate. Interpolation of the curve results in a minimum value at approximately just before the sixth mean value Ms2-6, its associated time delay as Ats and

Ate of, for example, 0.58 s can be used for the next can change. If there is too great a spread of the mean values or if a new fiber section is processed, a completely new measurement is carried out without taking stored values into account. How to

Embodiment of Figure 5 is carried out, two can with each can change Mean values Ms2 for the beginning of the can change are formed from the time delay Ats and the end of the can change from the time delay Ate with the associated deviations from the target value, so that the second can change takes place with an optimized time delay. In the controller 20 of the card 100, further boundary conditions can be stored, namely that the optimization of the time delay Ats and Ate, for example, only with a speed difference of the rollers of at least 80 m / min and / or only with a ratio of the delivery speed of the sliver when changing cans to the normal delivery speed should intervene by at least 80%.

Reference number

100 card

1 feed roller

2 dining table

3a, 3b, 3c lickerin roller

4 drum

5 doffing roller

6 scraper roller

7, 8 nip roller

9 Fleece guide element

10 pile funnels

11, 12 take-off rollers

14 carding element

15 jug

17 revolving lids

20 Control

M1 drive feed roller

M4 drum drive

M5 drive consumer

51 Feed tray sensor

52 Belt take-off sensor v Speed of the rolls u Speed of the rolls t Time tk Time of the can change

Ats time delay to start the can change

Ate time delay to the end of the can change

Ms2 mean value at the tape take-off sensor

At the mass change of the sliver ms2 sliver mass at the sensor sliver take-off

Ss2 standard deviation at the sensor tape withdrawal

Claims

1. A method for controlling a card (100) with at least one feed roller (1) and a doffer (5), each of which has separate controllable drives, the card (100) being designed to produce a sliver from fiber flocks or a wadding can be stored in cans (15), whereby the can change

The circumferential speed of the feed roller (1) is changed and the circumferential speed of the doffer (5) is subsequently changed with a time delay (Ats; Ate), with a sensor (S2) which is designed to measure the mass of the sliver produced or the change in mass of the sliver produced to determine, with each can change a controller (20) of the card from the signal of the sensor (S2) the

Standard deviation (Ss2) of the mass change (Am) of the sliver is determined and a mean value (MS2) is assigned to it, the controller (20) being designed to optimize the time delay (Ats; Ate) by means of at least two mean values (MS2).

2. The method according to claim 1, characterized in that before the can change, the peripheral speed of the feed roller (1) is reduced and with a time delay

(Ats) the peripheral speed of the pickup (5) is reduced.

3. The method according to claim 1, characterized in that at the end of the can change the peripheral speed of the feed roller (1) is increased and the peripheral speed of the doffer (5) is increased with a time delay (Ate).

4. The method according to any one of the preceding claims, characterized in that the change in the circumferential speed of the feed roller (1) and the pickup (5) takes place with the same or different acceleration or deceleration.

5. The method according to any one of the preceding claims, characterized in that the time delay (Ats) to the start of the can change is equal to or not equal to the time delay (Ate) to the end of the can change.

6. The method according to claim 1, characterized in that the controller is designed to determine a minimum from at least two mean values (MS2), from which the optimal time delay (Ats; Ate) is formed.

7. The method according to claim 1, that at the beginning of the first can change the time delay (Ats; Ate) is specified by at least one value that can be stored in the controller.

8. The method according to any one of the preceding claims, characterized in that the controller (20) is designed to control all drives of the card and at least the determined fiber mass on the sensor (S1) of the feed trough (1) with the determined mass of the sliver on the sensor ( S2) and control the associated drives (M1, M5).

9. The method according to any one of the preceding claims, characterized in that the optimization of the time delay (Ats, Ate) only at a predetermined speed difference of the rollers (1, 5) and / or only at a predetermined ratio of the delivery speed of the sliver when changing cans to normal Delivery speed starts.

10. Card (100) with at least one feed roller (1) and a doffer (5), each of which has separate controllable drives (M1, M5), with a sensor (S1) which is designed to measure the mass of the card ( 100) to determine incoming fibers or wadding, with a sensor (S2) which is designed to determine the mass of the sliver produced or the change in mass of the sliver produced, with a controller (20) which is designed to determine the method of operation to carry out the card according to one of the preceding claims.