CH685247A5 - Method for controlling a fibre-processing installation - Google Patents

Abstract

A method for controlling a fibre-processing installation which comprises a series of processing stages (42-56) in order to deliver fibre material as a predetermined fibre structure, the properties of this structure being capable of being influenced by a suitable selectively adaptable processing of the fibre material during the run through the installation, and a detectable property of the intermediate product and therefore a corresponding property of the structure being fixed in at least one intermediate stage (46-52). A signal (KFA) is obtained in this intermediate stage (46-52), and this signal corresponds to the detectable property and is used for regulating the preceding stages. <IMAGE>

Description

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description

This invention relates to an information acquisition or signal generation method which is particularly suitable for use in a process control system for a spinning mill. The information or signals obtained can be used for control purposes or for operator support.

State of the art

Today's conventional spinning plant takes fiber material in the form of bales as a template and converts it through a chain of different processing stages into a yarn that has to meet a predetermined quality specification. It is a goal to be able to control this conversion automatically. This is an extremely difficult task, for various reasons, of which only a few categories are mentioned, namely:

- the various requirements that are placed on the product of the spinning mill (yarn) by further processing into an end product (e.g. a woven or knitted article),

the number of processing stages involved in the conversion of a fiber material into a yarn,

- The various technological influencing factors that play a role in every processing stage.

It has already been proposed to divide the spinning line into the "areas", each of which is assigned its own process control computer, with various divisions being proposed by different bodies (cf. DE-A 3 924 779, Maschinenfabrik Rieter AG, and DE-A 3 906 508, Murata Kikai K. K).

It has also been proposed to link the first processing stages of the spinning line (the blowroom and the carding machine) for control purposes - DE-A 3 237 864, EP-A 0 303 023 and US Pat. No. 4,876,769. Proposals have now been made which make it possible to control or regulate both the composition of the material to be processed and the processing of this material in the first stages of the spinning line - EP-A 0 362 538; EP-A 0 402 940, EP-A 0 399 315 and EP 90 810 454.0.

It is still conventional practice today to monitor the product of the card (card sliver) for uniformity and to regulate or control the card in such a way that the best possible or a predetermined uniformity of the card sliver is achieved (see, for example, US Pat. No. 4 271 565).

Data transmission systems are also provided today to connect the spinning line and its controls with a higher-level process control system. U. Meyer and H. Howald on the occasion of the VDI annual conference in Aachen on January 30 and 31, 1991 - VDI report no. 879. The first implementation plans for process control systems in the spinning mill aim at a substantial improvement of the operating support rather than a “fully automated operation” - see PCT patent application no. PCT / CH 91/0097 from April 23, 1991 (CH-PS 683 009).

The efforts of the various companies operating in this area are largely directed towards the already mentioned first stages and the last stages (final spinning or roving spinning stage) of the spinning line and the subsequent winding machine (for ring yarn) with the process control system connect - see EP-A 0 365 901. Between these first and last stages there are still some processing stages today which have to fulfill essential tasks in the processing of the material and can deliver important information / signals to the process control system.

Presentation of the invention

It is the object of this invention to reduce the complexity of the above-mentioned overall task of automating the spinning line continuously by separating identifiable part tasks.

The invention provides a method for controlling a fiber processing system, which comprises a sequence of processing stages in order to deliver fiber material as a structure with essentially predetermined properties, the properties of the structure being influenced by suitable, selectively adaptable processing of the fiber material in the course of the system can be, and in at least one intermediate stage of this system, a determinable property of the product of this stage is determined and thereby a corresponding property of the structure is decisively influenced or determined.

The method is characterized in that a signal is obtained in the intermediate stage mentioned, which represents a measure of the stated property of the intermediate product.

This signal can be used to control or regulate at least one processing stage which the fiber material has to pass through before it reaches the intermediate stage mentioned and which influences the ascertainable property. However, the signal can also be displayed in a suitable form and can thus be used to assist the operator.

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In a particularly advantageous example of this method, the intermediate stage is a combing and the ascertainable property is the short fiber content of the material to be processed. The previous stage is the cleaning, opening or carding of the facility. The signal obtained in the combing can be used to control or regulate a mixing process and / or to control or regulate the intensity of the opening and cleaning of the fiber material. Where the dead time of the intermediate processing precludes regulation based on the signal obtained in the combing room, the signal can be processed for operator support, e.g. an alarm regarding the behavior of the preceding stages or regarding the material presented is made available.

The invention also relates to a fiber processing system, characterized by means for obtaining the said signal and control or regulating means for the preceding stage, which can influence the property that can be determined. An automatic control intervention can be provided. However, a display means can also be provided which serves as a decision aid for an intervention in the processing to be carried out by the operating personnel.

The state represented by said signal is preferably compared with a predetermined target state (e.g. in a computer) in order to determine any deviations from the target state. When such a deviation is ascertained, a control procedure is preferably carried out initially to determine whether this deviation is not attributable to the intermediate stage (e.g. the combing shop) itself. In the latter case, no control or regulation signal is supplied to the control means for the preceding stages, but the faulty state of the intermediate stage mentioned itself is indicated or corrected by suitable interventions. Only if no faulty condition of the relevant intermediate stage is determined should a control or regulation signal be delivered to the preceding stage or to its operation.

The foregoing comments regarding the invention deal primarily with the material composition, particularly the short fiber content. As will be explained in more detail below with reference to the figures, the short fiber content of the yarn is determined (determined) by the combing shop. But there are also other characteristics of the intermediate products of a spinning mill that are important for the end result.

An important quality feature of every fiber structure is its so-called «uniformity», which can be represented as the fiber mass per unit length of the structure.

In a well-run spinning mill of today's conventional design, the uniformity of the end product (yarn) is essentially determined by the end spinning process (flyer and ring spinning or rotor spinning or new spinning process). The preparation levels contribute a relatively small proportion to the end result (to the unevenness).

However, it must never be concluded that the uniformity control in the preparation stages can be neglected. A gross mistake in a preparation stage can also occur in well organized spinning mills and can have a significant impact on the end result. Furthermore, the competitiveness of a spinning mill depends on very small differences in its product compared to the products of its competitors. It is therefore important to be able to reduce even the smallest contributions to the unevenness. It should be noted that there is no possibility in the final spinning process (at least with the spinning machines available today) to correct uniformity errors in the original material. In the final spinning process, efforts tend to limit the contribution of the final spinning process itself to the unevenness.

For these reasons, measures are usually taken in the preparation stages to improve the uniformity of the intermediate product at each processing stage or at least to keep it under control. As a last measure before final spinning, fiber bundles are often subjected to a draft in a regulating drafting system in order to improve the uniformity of the bandage before feeding into the final spinning process.

From the above it will be clear that a regulating drafting system is not able to determine the uniformity of the end product of the entire spinning line (of the yarn) because this result is determined by the end spinning process itself. However, such a drafting system is able to determine the contribution of the preparation stages to the unevenness of the end product, and it is the task of such a drafting system to reduce this contribution to a minimum. If the regulating drafting unit succeeds in fulfilling this task, there is no longer any information in its intermediate product and in the products of the stages following it which enables a conclusion to be drawn about the operating behavior of the processing stages preceding the drafting unit.

According to a second aspect of this invention, at least the last regulating drafting device or the last uniformity regulation before spinning is intended as a control center for the uniformity of the intermediate products from the processing steps preceding the corresponding processing step and supplying it. Any regulating drafting unit or uniformity regulation can be formed as such a control center.

In principle, each belt-forming or fleece-forming or cotton-forming spinning preparation machine could be provided with its own regulating drafting unit or uniformity regulation and with an evaluation which is capable of using the drafting unit or from the regulation

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performed regulatory work to check the quality of the original material in terms of uniformity. A line with such machines is effectively divided into sections, each of which is terminated by a regulating drafting device or a regulation, this drafting device or this regulation, with respect to uniformity, serving as a control center for the section assigned to it.

If it is not possible or not desired to provide each preparation machine with its own regulating drafting device or its own regulation, at least one regulating drafting device or one regulation before the final spinning process is provided, which serves as a control center for a section of the processing line with regard to uniformity, who supplies him or her with template material.

The invention (in this aspect) is applicable to both long-wave and short-wave uniformity fluctuations, wherein different regulating means can be provided for different types of fluctuation.

The signals obtained by this invention can be linked to a material flow tracking system in order to enable or provide a fault diagnosis. A suitable material flow tracking is described in DE-A 4 024 307 dated July 31, 1990, although this invention is not restricted to use in such a combination. The invention will now be explained in more detail by means of examples and the figures of the drawings. It shows:

1 is a schematic outline of a spinning plant for processing fiber bales up to the spinning of ring yarn,

2 shows a diagram to illustrate the same spinning mill, but for simplification the different process stages have been shown without resolving each stage in its individual machines,

3 shows a stack diagram of a typical fiber material for processing in a so-called short fiber spinning mill,

4 is a schematic plan view of a bale opener,

5 shows a schematic side view of a fiber opening or cleaning machine, FIG. 6 shows a schematic representation of a process control system according to our DE patent application No. 3 924 779 from June 26, 1989,

7 is a schematic side view of a combing machine according to our German patent DD 286 376,

8 shows a schematic illustration of a single combing head of the machine according to FIG. 7, FIGS. 9A and 9B show two time diagrams for explaining different measuring principles,

Fig. 10 is a diagram for explaining various measuring arrangements for obtaining a suitable signal in the combing, and

11 shows a schematic illustration of a preferred drafting system drive for a regulating drafting system, specifically according to EP-A 0 411 379.

The following description first deals with the spinning line as a whole and the process control system, then the material composition and the combing and then the uniformity and the regulating drafting system.

The spinning line is structured as follows:

The spinning mill shown in FIG. 1 comprises a bale opener 120, a coarse cleaning machine 122, a mixing machine 124, two fine cleaning machines 126, twelve cards 128, two draw frames 130 (first draw frame passage), two combing preparation machines 132, ten combing machines 136, four draw frames 138 ( second route passage), five flyers 140 and forty ring spinning machines 142. This is a conventional arrangement today for the production of a so-called combed ring yarn. The ring spinning process can be replaced by a newer spinning process (e.g. rotor spinning), in which case the flyers are no longer necessary. However, since this invention deals with the preparation stages before final spinning (including any final spinning preparations in a flyer stage), the explanation in connection with conventional ring spinning is also sufficient for the application of the invention in connection with new spinning processes. Combing can also play a role in the new spinning processes, especially when higher quality is required.

The spinning mill according to FIG. 1 is again shown schematically in FIG. 2, in which case the machines have been combined into “processing stages”. According to this approach, the bale opener 120 and the coarse cleaning machine 122, mixing machine 124 and fine cleaning machines 126 together form a so-called cleaning shop 42, which supplies the carding machine 44 with largely opened and cleaned fiber material. Inside the blow room, the fiber material is transported from machine to machine in a pneumatic transport system (air flow), which system is completed in the carding machine. The cards 128 each provide a strip as an intermediate product, which has to be deposited in a suitable container (a so-called «can») and transported further.

The first route passage (through the routes 130) and the second route passage (through the routes 136) each form a processing stage 46 or 52 (FIG. 2). In between, the combing preparation machines 132 form a processing stage 48 (FIG. 2) and the combing machines 134 form a Ver4

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working level 50 (Fig. 2). Finally, the flyers 138 form a spinning preparation stage 54 (FIG. 2) and the ring spinning machines 140 form a final spinning stage 56 (FIG. 2). These last two processing stages will not be discussed in more detail in this application.

The process control system is not an essential feature of this invention, which also offers advantages if the signals or information obtained are used directly (without rerouting via a process control system). However, the preferred embodiment provides for the use of the invention in combination with a process control system. Examples of such systems are briefly discussed below.

In our German patent application No. 3 924 779 dated June 26, 1989, we describe a process control system according to which a spinning mill is organized into "areas" and signals from one area can be used to control or regulate previous areas. An example of such a system is shown schematically in FIG. 6, the system comprising three areas B1, B2 and B3 and each area being assigned its own process control computer R1, R2, R3. Each computer R1, R2, R3 is connected to the machines or machine groups of its own area for signal exchange (indicated schematically in FIG. 6 by the connections 84) and the computers are also connected to one another for signal exchange (in FIG. 6 schematically by the connections) 86 indicated). It will be clear to the person skilled in the art that the illustration in FIG. 6 is purely schematic. Of course, a single process control computer can be provided, which is connected to all areas of the spinning plant and carries out the desired signal exchange between these areas. The version shown with a process computer R per area B represents a reasonable version, which is assumed for this explanation.

The area B1 comprises the blowroom 42 and the carding machine 44 (FIG. 2).

The area B2 comprises both the two route passages 46, 52 (FIG. 2) as well as the combing preparation stage 48 and the combing 50.

The area B3 comprises the flyers 54 and the final spinning stage 56 (FIG. 2).

The areas B1 and B2 are important in connection with the preferred embodiment of this invention, signals obtained in the combing area (in the area B2) being used to control or regulate machines in the area B1 via the computers R2 and R1 . The acquisition of the appropriate signal is discussed in more detail below with reference to FIGS. 7, 8 and 9.

A process control system in the spinning mill is preferably designed or arranged and programmed for material flow tracking. The importance of this task and approaches to a solution are contained in the article "Computer-aided transport systems in textile production" by Uwe Behrens (Melliand Textile Reports, 7/1985, page 499). The solution preferred by the applicant is, however, shown in German patent application No. 4 024 307.9 dated July 31, 1990 and the corresponding PCT application PCT / CH91 / 00151.

Another important task of the process control system is operator support. Today's conventional spinning mill includes a variety of devices, programs and aids, which are intended to help the operating personnel to carry out their increasingly complex work efficiently and efficiently. In the next generation of "fully automated" spinning mills, it will be essential to fundamentally integrate operating support into the process control system. Such a solution has been proposed by the applicant in PCT application PCT / CH 91/00097 (CH-PS 683 009).

The “architecture” (structure) of the process control system is also important because of the complexity of the spinning line, especially when it comes to information transfer. The solutions proposed by the applicant in this regard can be found in EP-OS 513 339.

The end result of the schematically represented spinning process is influenced by a large number of factors which are not to be dealt with individually here. An important factor is the raw material to be processed, which can be represented as a group of individual ascertainable fiber properties (e.g. fiber fineness, fiber type, fiber strength, etc.).

An essential property for the end result of the spinning process is the fiber length, which can only be sensibly determined and represented in terms of the number of fibers to be processed by statistical methods. The fiber length property of a certain raw material is therefore represented by a so-called stack diagram (Fig. 3) (see page 24 of the manual «Textile Fibers: Testing and Quality Control»; author: SL Anderson in Manual of Textile Technology, Quality Control and Assessment, publisher: The Textile Institute). From this diagram, the proportion (percentage) of fibers in a given length range can be determined for the raw material in question. The importance of fiber length for spinning is known from the manual “Technology of Short Staple Spinning”, author: W. Klein in Manual of Textile Technology, Short Staple Spinning Series, (Volume 1), publisher: The Textile Institute.

When processing natural fibers (especially cotton fibers) it is not possible to "order" a raw material with a predetermined stacking diagram. Rather, the desired diagram must be generated by suitable processing of fibers from different origins (“provenances”). In particular, there are three processing stages that can influence the stack diagram of the material to be spun, namely:

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- the blow room

- the carding machine

- the combing.

The effects of the blowroom and carding are only briefly described below, since these steps are only indirectly affected by this invention.

There are basically two ways in the blow room or card shop to influence the stack diagram of a raw material, namely:

- by presenting fibers of different lengths (provenances), and

- by the intensity of the fiber processing, a higher intensity necessarily leading to greater fiber damage (shortening).

Examples of these two possibilities have been indicated schematically in FIGS. 4 and 5.

FIG. 4 schematically shows a bale opener of the type which is conventional today with a tower 60 which can be moved back and forth along a channel 62. The tower 60 has a boom 64 which is equipped with a bale opening unit (not shown). In addition to the channel 62, fiber bales are placed in bale groups 66, 68, 70, 72. When the tower 60 is moved back and forth with the boom 64 above a given bale group (in FIG. 4, above the bale group 68), the opening unit detaches flakes of fiber from the surface of the bale and feeds them into the via a pneumatic conveyor system (not shown) Channel 62. Afterwards they can be delivered to the other machines of the blow room and finally to the carding machine via the above-mentioned transport system.

If the bale groups are now organized according to provenance (so that, for example, fibers of a first provenance are present in bale group 68 and fibers of a second provenance in bale group 66), the stack diagram of the material to be spun can be influenced by the bale opener having a larger amount of fibers e.g. forwarded from the Bailengruppe 68 as from the Ballenengruppe 66 for processing. In this way, the so-called fiber mixture can be roughly influenced.

A further development of the conventional system has been shown in European patent applications EP-A 0 362 538 and EP-A 0 402 940, according to which the fiber mixture is specifically put together. The corresponding procedure requires control, which has to be provided in connection with the blowroom / carding step.

Figure 5 shows schematically a rotatable drum 74 of a cleaning machine e.g. a fine cleaning machine 126 (Fig. 1). This drum 74 operates e.g. together with a grate, which consists of individually adjustable grate bars 76 (only one grate bar 76 is shown in FIG. 5). Each grate bar 76 is rotatable about an axis 78 and has a working head 80 at its end next to the drum 74. By adjusting the grate bar 76 about the axis 78, the position of the working head 80 relative to the drum 74 can be changed. This affects the intensity of processing during material cleaning. More intensive processing means a higher degree of cleaning, but at the same time greater fiber damage (shortening) of the processed fiber material. The setting of the rods 76 can be carried out manually, but can also be effected automatically via servomotors 82. Other places where more intensive fiber processing is possible at the expense of higher fiber damage (shortening) are the bale opening and the carding. A method of specifically utilizing this effect has been shown in European patent applications EP-A 0 399 315 and EP-A 0 409 772.

The last stage, which influences the stack diagram of the raw material to be spun and therefore defines the final spinning process, is the combing and the function of this stage is discussed below for the time being. Conventional combing machines are required today, so that it is unnecessary to explain the construction (construction) and mode of operation of a combing machine in detail here. Such details are e.g. from the book "Drawing, Combing and Roving", author: Zoltan S. Szalocki, publisher: The Institute of Textile Technology or from the manual "A Practical Guide to Combing and Roving", author: W. Klein in Manual of Textile Technology, Short Staple Spinning Series, (Volume 3) Editor: The Textile Institute, removable. A modern combing system is described in the article “Combing as a decisive economic factor in short-staple spinning” by Dr. G. Mondini shown in Melliand textile reports, 5/1990, page 330ff.

From the sources listed, it will be clear that the main function of the combing machine is to remove fibers from the process as a waste shorter than a determinable minimum length. This effect can best be illustrated in the diagram according to FIG. 3. It is assumed that the blowroom 42 or the carding machine 44 supplies the combing machine 52 with a raw material with a fiber characteristic C according to the stack diagram shown in FIG. 3. The combing machines 136 (FIG. 1) of this combing are set in such a way that they excrete all fibers shorter than X mm as an outlet (it serves as a separation point with respect to short fibers). Under the assumed conditions, these short fibers which have been separated out represent a percentage of Y% of the original material provided by the preparation stage 50 (FIG. 2). The relationships shown in FIG. 3 represent a desired state. Deviations from this desired state can be determined by determining the in the combing out of the short fiber fraction discernible and this results in possibilities for controlling or regulating the blow room and / or the carding machine. It should be mentioned here that the combing machine is not just short

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but also excretes nits and dirt. In terms of quantity, these exits are negligible compared to short fiber excretion.

Fig. 7 is a copy of Fig. 1 of our previous EP patent application No. 376 002 (DD 286 376) and shows a schematic side view of a combing machine with a controlled drafting system. For the time being, only the basic structure of the comber (without taking the draft control into account) will be discussed.

Fig. 7 shows a combing machine 1, e.g. eight combing heads 2, of which only four are shown in the illustration. A single combing head 2 is shown schematically on a larger scale in FIG. 8 (looking in the longitudinal direction of the machine). On the carrier rollers 110 (FIG. 8) in each combing head 2 there is a wadding roll 3, the wadding 4 of which is fed to the combing device 5 via a feed device 112 (FIG. 8). The combing device 5 can, as is generally known, consist of a pliers unit 114 (FIG. 8), a circular comb 116 arranged underneath this and a fixed comb 118, with respect to the conveying direction, arranged behind the pliers unit with subsequent tear-off rollers 119.

The combed nonwoven fabric released by the tear-off rollers 119 passes via a take-off table 6 (FIG. 7) into a take-off funnel (not shown in any more detail). In the draw-off funnel, the nonwoven fabric is combined into a sliver, or sliver. This process is supported by a pair of draw-off rollers 7 which are arranged downstream of the respective draw-off hopper and which deliver the comb-pull belt to an outlet table 8. In order to further convey the slivers 10 next to each other on the outlet table 8, sliver guides 9 are provided which are offset from one another in the horizontal direction. The fiber slivers 10 guided parallel to one another arrive at a drafting arrangement 11, a measuring device 12 being provided at the entrance of the drafting arrangement 11, which scans the strength of the incoming fiber slivers. The measuring device 12 can e.g. be constructed optically or mechanically.

After passing through the measuring device 12, the slivers pass between the input rollers 13 of a pre-draft zone 14 to a pair of center rollers 15, which are at the same time the feed rollers for a subsequent main draft zone 16. Via the delivery rollers 17 at the exit of the main drafting zone 16, the stretched strips 10 enter a strip hopper 18, shown schematically, and are combined there to form a combed strip 19 with the aid of the extraction rollers 20. A pressure rod 21 is attached in the draft zone to guide the fibers. This pressure rod 21 could also be arranged in the main drafting zone 16.

The combed belt 19 delivered by the take-off rollers 20 arrives on a conveyor belt 22 and is transferred to a can press 23. The Kammzugband 19 is placed in a can 26 via the calender rollers 24 and the funnel wheel 25.

The shorter fibers are taken up by the needling 117 (FIG. 8) of the circular comb 116 and removed from the circular comb 116 by a comb cleaning device KR. The cleaning device KR forwards these short fibers which have been discharged to a suction channel 121 which runs past all eight comb heads 5 and conveys the outlet from all of these heads to a collecting container SB. The excreted material can then e.g. can be reused in a suitable recycling process, but this does not play a role in connection with this invention and is not to be described in more detail here.

According to Fig. 3, it is now desirable to obtain a signal which corresponds to the short fiber content of the original material for the combing. This must be carried out using a suitable arrangement of measuring sensors. In principle, it would be possible to individually measure or determine the short fiber content in each comb head, which would enable very precise monitoring of the combing level itself. However, such an arrangement results in very high capital and maintenance costs and a considerable effort to set up the various measuring devices. In a preferred variant, the short fiber content is not determined or measured per combing head but rather per machine, which only requires one mass sensor arrangement per machine. This arrangement is connected to the process control computer R2 (FIG. 6 for the area B2 of the spinning plant. The possibilities for measuring or determining the short fiber content are discussed in more detail below. For the time being, however, the evaluation of the signals from the combing machines 136 (FIG. 1) treated in the computer R2 (Fig. 6).

It is first assumed that a target value with upper and lower tolerance limits has been defined for the short fiber component. If, for each combing machine, the signal delivered to computer R2 indicates that the short fiber fraction that has been eliminated lies within the specified tolerance range, there is no reason for computer R2 to intervene in the process with regard to the stack length. If a change in the signal from a single combing machine indicates that the short fiber component that has been eliminated has migrated outside of the specified tolerance range in this machine, a similar deviation in the other (processing the same raw material) machines must normally occur within a definable time in the event of a raw material fault interval can be determined. The computer R2 should therefore first wait to see whether similar deviations from the desired state are found in all machines in the group. If the deviations can be determined with only one machine, it cannot be concluded that there is a raw material defect, but only that there is a defect in the relevant machine or in the measuring devices arranged thereon.

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Under these circumstances, the computer R2 should shut down the affected machine and display it so that the defect can be remedied by the personnel.

If the measured or determined short fiber content of all combing machines in the group migrates at the same time, it can be clearly concluded that there is a raw material fault. The computer R2 then sends a corresponding signal to the process control computer R1, which is responsible for controlling or regulating the area B1. The computer R1 can then either set up a display so that corresponding new settings can be carried out by the personnel, or (by utilizing the various options for influencing the stack lengths) carry out a processing change in order to restore the desired state in the presentation of the combing. These possibilities have been indicated in connection with FIGS. 4 and 5.

If contradicting messages are received from the various machines of the combing, the computer R2 may have to conclude that there is a system defect and trigger a corresponding alarm.

If a regulation is to be considered, it is important to consider the expected “dead time” between the detection of an error and the entry of the correspondingly corrected material into the sensor's touch field. If this dead time is too long, the control should be dispensed with at all. Where e.g. If the "dead time" (from a possible standard procedure) between the carding and the combing is more than a few hours, an error in the blow room may have already been "corrected" by processing and replacing the faulty material when the defect was found in the combing. In such a case, the operating personnel should be made aware of the error by an alarm so that material can still be checked “in progress” (also between the carding machine and the combing shop). This is also important for today's conventional spinning mill, where the dead time between the carding and the combing is often a few days.

In view of the considerable time delays between the detection of a raw material error in the combing and the subsequent correction of this error in the combing material itself, it is hardly sensible in any case to forward a deviation signal from computer R2 to computer R1 continuously or quasi-continuously. It also makes no sense to react to short-term fluctuations in the result of the measurement or determination process. Rather, it is advisable to center these fluctuations over a certain time interval in order to identify any tendencies. The suitable time interval must be determined on a case-by-case basis and depends both on the running time of a winding load 3 (FIG. 7) and on the dead time in a possible control system.

Within this time interval, measurements can be made continuously (analogously) or discontinuously. The type of evaluation can vary from case to case with regard to the results of the measurement or Determination method are determined, as will now be explained with reference to the diagrams of FIGS. 9A and 9B. In both diagrams, the time is shown on the horizontal axis and the measured or determined short fiber content on the vertical axis. In both cases, a predefined measuring or determination interval I is used. In FIG. 9A it is determined empirically that the measurement results have an irregular course (characteristic), while the results of FIG. 9B have a regular course. In both cases a discontinuous measurement or Determination procedure assumed, which is represented here by five «measuring times» MT within the interval I.

In a system according to FIG. 9A, it is hardly possible to determine a tendency within the interval I. The measurement results must be collected for the entire interval and compared by means of a suitable evaluation with the measurement results from previous intervals to determine a tendency. The computer R2 can therefore at the earliest at the end of an interval I determine a raw material defect and deliver a corresponding signal to the computer R1. In contrast, in case 9B, the upward tendency of the short fiber component can already be determined within the interval I, so that intervention in the method can take place earlier within a specific interval. The computer R2 can be programmed in such a way that it checks the measurement results supplied to it according to predetermined tendencies (e.g. steady increase according to FIG. 9B) and reacts accordingly to the results of the test. In any case, this computer must be programmed to handle measured values according to FIG. 9A, since it cannot be predicted whether (and if so which) tendencies will occur.

FIG. 10 is a diagram for explaining various possibilities for measuring or for determining the short fiber content of the feed material of a particular combing machine 1 (see also FIG. 7 and FIG. 8). The arrows point to the material flow. The arrow v points to the feeding of the original material in the machine 1, the arrow L to the delivery of the intermediate product (belt) of the machine and the arrow A to the exit (the noose).

If V, A and L are considered as material quantities per unit of time, the relationships can be represented by the following equations:

(1) V - A = L or (2) A = V - L

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It follows that the short fiber content (KFA) can be determined using the following equation: (3) KVA A = V-L A = A

V V L + A X

This means that the short fiber content can be determined by measuring A and V or by measuring V and L or by measuring A and L (according to a suitable system according to FIG. 9A or 9B). Under certain circumstances, the short fiber content can be determined with sufficient accuracy by measuring the amount of combed A and by determining a value X, where X is an estimated value which roughly reproduces the original quantity V. The value X can e.g. are derived from the production set for the combing machine. From Fig. 10 it will be clear that the most diverse possibilities for measuring or determining the short fiber content are open. The amount of waste A should be measured or determined on the combing machine 1 itself. The template quantity V could e.g. from preparation stage 50 (Fig. 2). The delivery L can be determined in the can press 23 (FIG. 7).

The combing machine has a clearly identifiable influence on the stack diagram of the raw material to be spun by this machine eliminating the shorter fibers from the process. The amount of waste on the combing machine clearly reflects this influence, because the amount of the combed consists almost exclusively of short fibers (the amount of dirt in the combing material and the nits it contains are negligible in this respect). For given settings of the combing machine and for a given design of the cotton wool (wadding thickness or degree of parallelism of fibers), the amount of waste indicates directly the short fiber content. This statement applies to today's combing machines. If in the future the percentage of dirt or nits in the comb increases so much that it can no longer be neglected, fixed proportions of these components could be determined with random samples in the laboratory.

The combing machine itself can be set such that fibers shorter than a certain length are excreted, so that the subsequent stages are spared the problem of short fibers (separation point function). It also follows from this that after combing there is no longer any “information” regarding the performance of the previous stages in connection with short fibers in the material itself. This information was "deleted" in the comb.

However, the end result of the spinning process depends on many other influencing factors, in particular on the numbering of the band and on the CV values for these bands. For this reason, it is particularly useful to design the drawing frame 11 (FIG. 7) of the combing machine as a regulating drawing frame. For the sake of completeness, the control device 27 for the drafting system 11 is also briefly described here, although this arrangement is not absolutely necessary for the application of the invention in connection with the material composition.

The lower roller of the roller pairs 13, 15 and 17 is driven by the main motor M, a planetary gear 28 being interposed for driving the lower roller 15 and the drive of the lower roller 13 being removed directly from the lower roller 15. A control motor M1 is assigned to the planetary gear 28 and is controlled via a control unit 29. The control unit 29 receives pulses from a setpoint value stage 30, in which the measurement voltage initiated by the measuring device via a signal converter 31 and a timing element 32 is compared with the control voltage output by the master tachometer 33 of the main motor M and results in a target voltage for the control unit.

Before entering the calender rolls 24, a belt monitor is additionally provided for monitoring the regulated sliver belt.

If the measuring device 12 determines a difference from the nominal value strip thickness, then in this case a time delay is applied via the control device 27 to the control motor M1, which engages in the planetary gear and causes a change in speed of the center roll 15 and thus also of the input roll 13, while the delivery roller 17 has an unchanged speed. This means that the distortion is adjusted by the measuring device 12 as a result of the changed speed difference between the center roll 15 and delivery roll 17 of the determined strip thickness. In order to protect the combing machine itself from these speed changes in the drafting system inlet, a buffer store can be provided in front of the drafting system. The regulated drafting zone can also be located between the roller pairs 15 and 17. In this case, the pair of rollers 17 will have a variable speed. In this case, the belt store would be located between the drafting device outlet and the chamber press.

Different drafting arrangements with other control devices than the version shown here can be used, as will be described in more detail below.

It is also conceivable to arrange a further pair of rollers (not shown) after the pair of take-off rolls 7, which is driven at a somewhat higher speed in order to apply a slight advance to the sliver before it reaches the take-off table and is doubled with the others.

Finally, it is necessary to adjust the overall production of the combing to the "demand" of the final spinning process. This quantity control is preferably effected in that

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Combing has a certain excess capacity in production output, and the individual machines are operated according to a so-called “stop / go process”. With a higher demand in the final spinning stage, the stop / go ratio is reduced and with a falling demand this ratio is increased. If for any reason it is not desired to operate the combing machines in the stop / go process, the number of comb cycles of the individual machines can be increased or reduced in order to adapt the delivery quantities per unit time to the demand of the final spinning process. These settings have no influence on the importance of measuring or determining the short fiber content. The measurement or determination of the short fiber content can also be independent of other quality features such as Volume number or CV are carried out and used. The problem of maintaining tape numbers or smoothing out CV fluctuations can e.g. at other processing stages (e.g. on the second route passage 54, FIG. 2). The invention can therefore be implemented even if the combing machines have no regulated drafting systems. Such drafting systems are very important for the invention in its second aspect.

The importance of uniformity for spinning can be seen in the aforementioned “Technology of Short Staple Spinning” manual. Today's conventional means of achieving the same can be found in the aforementioned book "Drawing, Combing and Roving" or in Volume 3 of the Short Staple Series by Textile Institute, "A Practical Guide to Combing and Roving".

The sensors in the inlet and outlet of a regulating drafting system each deliver a signal that corresponds to the uniformity fluctuations of the belt or fleece passing through the respective sensor. However, these signals are not necessarily usable, as can be seen from European Patent Application No. 0 412 448 and European Patent Application No. 477 589. From these two signals (if necessary after adjustment according to the aforementioned applications) it is possible to generate signals which represent both the so-called number compliance (long-term fluctuations - "drift") and the CV values (short-wave fluctuations).

However, it is also possible to extract the desired information from a further signal, namely the so-called control signal, which is used to control the controlled motor.

It has long been known to check the uniformity of an intermediate product in the laboratory (off-line) by obtaining appropriate signals and, if necessary, to intervene thereafter in the process. The theory of testing has been intensively developed and even enables statements to be made about the processing level that has caused a predetermined error to occur - see the “Uniformity Check” application manual from Zellweger, Uster AG, Switzerland (page 129ff).

In the course of the eighties it was also possible to obtain the necessary signals in operation (on-line) and to make them available to the operating personnel via a display for fault diagnosis - this is made possible by the "SLIVER DATA" system from Zellweger, Uster enables (see the aforementioned Volume 3 of the Short Staple Spinning Series). This device even provides a spectrogram of the incoming or outgoing material. However, it has not previously been proposed to evaluate the signals thus obtained via a process control system and to use them to control or regulate the preceding stages.

The regulating drafting unit acts as a uniformity-determining assembly. The route of the second passage (138, Fig. 1) serves in the conventional spinning mill as the stage which has proven the final spinning stage of fluctuations in the uniformity of the preparation machines (blowroom, carding machine and Vorwerk) (it serves as a “separation point” with regard to uniformity). The drafting systems of the spinning stages (flyer or final spinning machine) cannot be set automatically and therefore cannot compensate for errors in the original material.

Modern routes of these levels are now often provided with both a regulation and a control system, the regulation of number compliance and the control system serving to ensure a predetermined CV value. The latter function is particularly important after combing (because of the way the combing machine works) - see the aforementioned books. If the stretches of this passage fulfill their intended functions, there is no point in examining the performance of the previous stages according to the results in the spinning stages, since the relevant information is no longer available in the material to be spun.

Well, the route of the second passage is usually not the only processing stage that is provided with uniformity control. In principle, it would be possible to provide each processing stage with its own regularity control and / or regularity control, which does not necessarily have to be combined with a drafting system - see e.g. US Pat. No. 4,271,565. However, equipping each preparation machine with its own uniformity regulation was in any case a very complex design and is normally not an option, at least for cost reasons. But even if this complex implementation can be realized under given circumstances, the last stage before spinning can be determined as a control center in the sense that the results of the previous stages are checked here via the process control system and, if necessary, interventions in the previous stages are initiated become.

But even if more than one stage is provided with a uniformity control, the control of a stage upstream of the separation point will usually be less efficient than the control of the separation point itself, because repeated

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Interventions in the template material usually do not lead to an improvement in quality but often lead to a deterioration in quality. It is therefore important, also for technological reasons, to provide such interventions in as few places as possible, at least as far as balancing short-wave uniformity fluctuations is concerned. With regard to longer-wave fluctuations, on the other hand, it can be advantageous to provide the appropriate control or regulation also on upstream stages, in particular on the card.

A regulating drafting device to compensate for short-wave fluctuations in mass is necessary after the combs in order to smooth out the soldered parts as much as possible. As has already been shown in connection with the material composition, a "route passage" downstream of the combing can be integrated in the combing machine itself, i.e. The combing machine can serve as a "separation point" for both the short fiber content and for the "preparation uniformity". The expression “preparation uniformity” here means the uniformity of the original material that is delivered to the spinning stage, where it is no longer possible to improve the uniformity.

As has already been shown in connection with the material composition, an increased excretion of short fibers means a loss of material, which means a corresponding change in uniformity, which is noticeable on the combing downstream drafting system, i.e. additional regulating work is necessary in order to forward a band of a predetermined number to the spinning stage.

If the regulating drafting device is installed in the combing machine itself, the regulating work can be correlated with the separating work in the machine control, which receives both the combing measurement signals and the uniformity value signals. If the comber is not equipped with a regulating drafting system, a process control computer can carry out the required correlation if it is supplied with the required output signals of the two process stages.

This correlation enables the elimination of fallacies that could otherwise arise because the essential work of the combing machine (namely, the removal of short fibers) leads to a change in another property (the uniformity). Accordingly, this change in uniformity should not be interpreted as a "misconduct" of the preparation in relation to the uniformity, but (as with an increase in the number of combers themselves) must be regarded as a symptom of a material defect or a material processing error.

Control interventions can take place as follows: Tolerance limits can now be set in the process control computer for the material presented to the separation point, so that no intervention is made as long as the uniformity fluctuations of the incoming material are within these tolerance values. The tolerance values can be adapted to the performance options of the separation point in such a way that e.g. If the incoming material deteriorates, no action is taken if the separation point is still able to absorb the fluctuations in uniformity, with a minimal safety margin. Intervention is therefore necessary if it is determined that the deterioration has reached the safety reserve. However, trends can also be assessed in advance, as has already been described in connection with the material composition, in order to be able to carry out an intervention earlier if it is found that a steady deterioration has occurred, since during normal operation deteriorations and improvements approximate over time should compensate.

The system can also be used to “optimize” the line in the sense that a deterioration in quality is initiated in the previous stages if the separation point still has unused reserves. Since quality is normally achieved at the expense of production, such an approach can lead to a more efficient use of the interactions between the processing stages in terms of production and quality. The same applies to the choice of raw materials - by mutually coordinating the processing in the various stages using the process control computer, it is possible to empirically determine the optimal settings for more delicate materials or the effects of cheaper materials.

When evaluating the uniformity test, the spectrogram is of crucial importance - only this analysis tool allows the targeted identification of the source of the error (see the aforementioned manual by Zellweger AG, Uster). In the preferred embodiment of this invention, the uniformity signals of the separation point are therefore obtained in such a way that they enable spectral analysis.

At best, the spectral analysis enables the processing stage that caused a certain error to be identified. Identifying a particular machine as the source of the error requires material flow tracking. Systems for material flow tracking are known but mostly very complex. To limit the length of this description, material flow tracking will not be treated as such in this application. However, the combination of the present invention with the material flow tracking in the process control system represents the preferred embodiment and a suitable material flow tracking is described in the aforementioned German patent application No. 4 024 307 and the statements contained therein are hereby included in the present description by this reference.

This material flow tracking is based on the simulation of the material flow in a computer or a computer system (with a plurality of interconnected computers). For this

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Replicas are defined as "material units" that can be determined by sensors in the system. The system is provided with such a sensor arrangement that

(i) the paths of the material through the system are divided into sections between sensors, the assignment of a material unit to a section representing a location accuracy sufficient for material flow tracking, and

(ii) the order in which the material units move past the sensors enables the units to be uniquely identified (without requiring the units to be marked).

The sensors are connected to the computer (system) in such a way that the movement of a material unit past a sensor can be recorded by the computer (system) and assigned to a time coordinate. The material units are thus assigned both location and time coordinates, which can be stored in the computer (system) long enough to enable the material flow to be determined later, i.e. at least until the time when these material units leave the plant.

Preferred designs of the regulating drafting systems are described below: The second aspect of the invention relates to the use of regulating drafting systems, i.e. Drafting systems in which the draft can be controlled or regulated in order to even out fluctuations in mass in a fiber structure. Such drafting systems are often used in so-called regulating lines in short fiber spinning, but can also be used on cards, combing machines and combing preparation machines in short fiber spinning. The same principles are of course also suitable for use in long-staple spinning.

The principles of control technology have been used in regulating drafting systems for several decades. This has made it possible to continuously improve the quality of the fiber assemblies processed (provided this quality is determined solely by the uniformity of the mass per unit length).

Over the same period, intensive efforts have been made to clearly define the term “quality” in relation to the uniformity of the fiber structure. These efforts have led to generally accepted test procedures with the consistent availability of suitable test equipment.

With the help of the technology previously used together with a quality-oriented organization of the spinning mill, it is now possible for every spinning mill to avoid or correct most (relatively coarse) errors and to produce fiber assemblies of good average quality.

Because of continuously increasing quality requirements, it is now necessary to increase this good quality level again. However, this leads to a technical area where it is no longer sufficient to apply the basic principles of control technology or the basic principles of statistical quality control in spinning. In order to achieve a further significant quality improvement, it is now necessary to take a closer look at the more intimate interactions of the measuring principles, control and regulation principles used, drive systems, distortion forces and material properties. It is always necessary to keep in mind the principles of uniformity testing for fiber associations that have already been established by standards.

Today, quality control in the spinning mill is largely carried out in the laboratory (“off line”). For this purpose, samples are taken from the processing line, carried to the laboratory and checked. The test results should enable conclusions to be drawn about the division of the machines or the adaptation of the material to be processed to the requirements for the desired end product. The world's leading manufacturer of test equipment is Zellweger G, Uster, Switzerland. The application manual of this company, entitled «Uniformity test», comprises approx. 230 pages and describes at least six different test criteria that provide different information for assessing the uniformity of a fiber structure (namely the diagram, the imperfections or rare errors, the spectrogram, the mean factor and the length variation curve).

In the laboratory, (off-line method) there is time to analyze the different information, to make an appropriate interpretation of the different results and to determine the corresponding conclusions. If an attempt is made to use such methods in normal operation "on line", where corrective intervention should be made in the process on the basis of the measured values that have just been determined, it should come as no surprise that there is a great risk of a wrong or a fallacy.

The previous proposals for a more precise inspection of products in operation (“on line”) are not aimed at enabling an intervention in the processing, but rather to trigger an alarm, for the acquisition of operating data or for the analysis of a process (eg US 4,758,968), so that a closer examination takes place by the staff or the staff can carry out targeted maintenance work. In this category belongs a system according to DE-PS 3 237 371, according to which a yarn produced by the nozzle spinning process is checked in operation both with respect to the spectrogram and with regard to the Uster value (unevenness coefficient). This identifies faults in the drafting system of the jet spinning machine itself, which can lead to the replacement of the defective parts. This procedure does not allow conclusions to be drawn about the running behavior of the preparation stages.

A proposal for monitoring a route can be found in EP 340 756. After a first one

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In a variant of this proposal, limit values are to be determined for a signal supplied by the outlet measuring device, and an alarm can be triggered or the machine can be switched off when a limit value is exceeded. In this case, the product (the fiber structure supplied) should be checked by the personnel. Depending on the results of this check, measurement errors or control errors should be concluded.

A second variant of the same proposal provides for the determination of limit values for the actuating signal which determines the delay, the triggering of an alarm or the switching off of the machine also taking place when a limit value is exceeded. In this case, the stock fiber ribbon should be checked by the personnel, depending on the test results for faults in the inlet measuring system or in the production of the stock material (i.e. in the processing machines in front of this drafting system).

Monitoring the measurement signal from the outlet measurement system can convey certain information about malfunctions. However, this measure alone is certainly not enough to achieve a significant improvement in quality. The monitoring of the control signal proposed in EP 340 756 has hardly any advantages in combination with an alarm or when the machine is switched off. By the time the staff checked the defective fiber bundle, it had long been processed (corrected) by the drafting system, so that important information regarding the error is no longer available. Because the surveillance is set up to react only to a short-term (possibly rare) “outlier”, the piece of the fiber association to be examined by the staff probably does not contain a corresponding “event”, so that the risk of a fallacy again arises. The examination does not take place in the company but “off-line”.

It is the object of this invention, in a third aspect, to further develop the regulating drafting system in such a way that the interactions which are decisive for its function can be taken into account better than in the past.

The invention (in the third aspect) provides a regulating drafting device for fiber bundles, which has at least one draft zone, a controllable or regulable drive system for determining the amount of draft in said draft field, a programmable controller for the drive system and at least one sensor for determining the continuous fiber mass per Length unit is equipped at a measuring point. The drafting system is characterized in that a warp-determining signal is stored over a predetermined period and information for adapting the drafting system and / or for assessing the quality of the fiber bundles is obtained from the stored values. The information mentioned includes e.g. the CV value of the fiber bundle, the spectrogram of the fiber bundle and / or the length variation curve of the fiber bundle. The controller preferably comprises a digital signal processor e.g. the model 56001 from Motorola.

The delay-determining signal can be an output signal from a sensor or an actuating signal for the drive system. In the sense of this invention, a signal is “determining the delay” if it has an indirect or direct influence on the delay, even if other signals also have such an influence.

The information can be obtained by said controller and / or by a process control system, in the latter case the stored values are preferably conveyed to the process control system via the controller, e.g. according to our European patent application EP-OS 513 339. The control itself can only obtain such information if this control comprises a digital signal processor or a device with a similar or better computing power.

The sensor is preferably suitable for following short-wave mass fluctuations. In order to process such signals using digital technology, it is necessary to digitize them, which is done by periodic sampling. According to the preferred embodiment of the control system, the sampling rate is selected to be higher than 2000 Hz, preferably in the range 2500 to 3500 Hz. Such a signal can be processed in the processor according to the Fast Fourier Transform method in order to enable spectral analysis.

The sampling rate of the control preferably remains constant; the speed of the material passing through is changeable. The control is preferably also provided with a sensor which reacts to the infeed speed of the material, so that the control (despite the constant sampling rate) can perform a corrective action per incoming length unit. Appropriate storage means are provided.

This preferred embodiment has the advantage that the information is obtained from signals which are also used to control the correction interventions, which increases the uniformity of the information content of the various signals.

For the same or similar considerations, the operator support provided on the basis of the signals obtained according to this invention is provided via the operator interfaces (operator consoles or operator panels) of the machines concerned, as in the aforementioned PCT patent application PCT / CH 91/0097 (CH-PS 683 009). In order to limit the length of this description, the operating support will not be treated as such here. The remarks of PCT / CH 91/0097 are included in the present description by this reference.

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11 shows a schematic illustration of an exemplary embodiment of the route according to our European patent application No. 0 411 379.

In the system according to FIG. 11, several slivers 215.1-215.6, in the example six of them, are combined side by side to form a loose fleece and are guided through several roller systems 201-206. Due to the fact that the peripheral speed of the rollers increases in two stages in the direction of transport of the fiber material, this is pre-drawn over the first stage (pre-drafting) and further drawn over the second to the desired cross-section (main drafting).

The fleece emerging from the route is thinner than the fleece of the fed strips 215.1-215.6 and correspondingly longer. Because the warping processes can be regulated as a function of the cross section of the fed strips, the strips or the fleece are made more uniform as they pass through the section, i.e. the cross section of the emerging fleece is more uniform than the cross section of the fed fleece or strips . The present route has a pre-drafting area 211 and a main drafting area 212.

The belts 215.1-215.6 are fed into the line by two systems 201 and 202 of conveyor rollers. A first system 201 is e.g. from two rollers 201.1 and 201.2, between which the fed belts 215.1-215.6, which are combined to form a loose fleece, are transported. A roller system 202 follows in the transport direction of the belts, which here consists of an active conveyor roller 202.1 and two passive conveyor rollers 202.2, 202.3. During the feeding through the roller systems 201 and 202, the fed tapes 215.1-215.6 are brought together to form a fleece 216. The peripheral speeds vi and V2 (= Vjn) of all rollers of the two roller systems 201 and 202 of the feed are of the same size, so that the thickness of the fleece 216 essentially corresponds to the thickness of the fed strips 215.1-215.6.

The two roller systems 201 and 202 of the feed are followed in the transport direction of the nonwoven 16 by a third system 203 of pre-drawing rollers 203.1 and 203.2, between which the nonwoven is transported further. The peripheral speed V3 of the pre-drafting rollers is higher than that of the infeed rollers vi, 2, so that the fleece 216 is stretched in the pre-drafting area 211 between the infeed rollers 202 and the pre-drafting rollers 203, its cross section being reduced. At the same time, the pre-drawn rolls 203 are followed by a further system 204 of an active conveying roll 204.1 and two passive conveying rolls 204.2, 204.3 for the further transport of the non-woven. The peripheral speed V4 of the conveyor rollers 204 for further transport is the same as V3 of the pre-drawing rollers 203.

The roller system for further transport 204 is followed by a fifth system 205 of main drafting rollers 205.1 and 205.2 in the transport direction of the fleece 217. The main drafting rollers in turn have a higher surface speed V5 than the preceding transport rollers, so that the pre-drawn fleece 217 between the transport rollers 204 and the main drafting rollers 205 in the main drafting area 212 is further drawn to the finished drawn fleece, the fleece being brought together into a belt via a funnel T. .

Between a pair 206 of outlet rollers 206.1, 206.2, the circumferential speed V6 (= vout) of which is the same as that of the preceding main drafting rollers (V5), the fully stretched strip is led away from the line and placed, for example, in rotating cans 213.

The roller systems 201.2 and 204 are driven by a first servo motor 207.1, preferably via toothed belts. The pre-drafting rollers 203 are mechanically coupled to the roller system 204, the transmission ratio being adjustable or a setpoint being predeterminable. The gear (not visible in the figure) determines the ratio of the peripheral speeds of the inlet rollers (vm) and the peripheral speed V3 of the pre-drafting rollers 203.1, 203.2, and thus the pre-drafting ratio.

The roller systems 205 and 206 are in turn driven by a servo motor 207.2. The inlet rollers 201.1, 201.2 can also be driven by the first servo motor 207.1 or optionally by an independent motor 207.3. The two servomotors 207.1 and 207.2 each have their own controller 208.1 and 208.2. The regulation takes place via a closed control loop 208.a, 208.b or 208.C, 208.d. In addition, the actual value of one servo motor can be transmitted to the other servo motor in one or both directions via a control connection 208.e so that everyone can react accordingly to deviations from the other.

The mass or a quantity proportional to the mass, e.g. the cross section of the fed tapes 215.1-215.6 measured by an inlet measuring element 209.1. At the exit of the line, the cross section of the emerging strip 218 is then measured by an outlet measuring member 209.2.

A central computer unit 210 transmits an initial setting of the sol size for the first drive via 210.a to the first controller 208.1. The measured variables of the two measuring elements 209.1, 209.2 are continuously transmitted to the central computer unit via the connections 209.a and 209.b during the stretching process. From these measurement results and from the target value for the cross section of the emerging belt 218, the target value for the servo motor 208.2 is determined in the central computer unit and any other elements. This setpoint is continuously given to the second controller 208.2 via 210.b. With the help of this control system (the "main control"), fluctuations in the cross-section of the fed tapes 215.1-215.6 can be controlled by appropriate

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development of the main drafting process is compensated or the belt is compared.

The drafting system shown in FIG. 11 is designed for a draw frame, but can also be installed on a combing machine, but then the feeding cans are omitted (as can be seen from FIG. 7).

The lower part of FIG. 11 now shows the adaptation of this system to this invention in its third aspect. In a first embodiment, the central control 210 of the machine itself is assigned a memory 220, where the or certain signals of the drafting system control system are stored for evaluation. If the operating speed of the central processor in the controller 210 is high enough, such a high sampling rate can be selected that a spectra frame of the input signal (from sensor 209.1), the output signal (from sensor 209.2) and / or the control signals (to motors 207.1 and / or 207.2 emitted signals) can be obtained.

A draft control system according to FIG. 11 is normally designed not to carry out a control intervention in the material (a change in the material processing) continuously, but rather after a certain interval. The duration of this interval is preferably not chosen to be constant, but is adapted to the running-in speed in such a way that the interventions take place at the end of a predetermined fleece length. For this, the arrangement shown can be supplemented by the fact that the running-in speed e.g. is determined on the roller group 202 and used to control the processing interventions. Storage means (not shown) are then necessary in the draft control system in order to store the control signals and to activate them at the right time.

However, the values contained in the memory 220 are not evaluated as a function of the running-in speed but according to time. In a spectral analysis, the time functions are then converted into frequency functions using the Fast Fourier Transform method. The time required for this depends on the computing speed of the processor and the number of frequencies (or frequency ranges) that should be examined individually. For an adequate analysis of a template material, preferably at least 1024 individual frequency ranges are to be examined.

Such an evaluation requires a considerable computing or storage capacity in the machine itself. In many cases, this may not be present, so that the analysis must be relocated to a process control computer PLR. A data bus DB can be provided for this purpose, and the controller 210 can be provided with an interface SNM to this data bus, the computer PLR likewise comprising an interface SNR to the data bus.

In the process control computer, neither the computing speed nor the storage capacity will normally limit the desired analysis - however, a prerequisite for this analysis is the process control computer's access to the "raw data" of the relevant sensors, e.g. as shown in the aforementioned Swiss patent applications No. 189/91 and EP-OS 513 339. The statements after these applications are also included in the present description by this reference.

However, the aforementioned «raw data» are not to be understood as the actual output signals of the relevant sensors, but these signals can be processed by the machine control (at least for the transfer to the process control computer). It is important that the essential information content for the intended analysis is retained.

The term “separation point” has been used at some points in this application. This term is not common in spinning technology and is therefore briefly explained in more detail below.

The "separation point" is the last point of a spinning line that carries out a specific change in the material to be processed (e.g. change the material composition - eliminate short fibers - and / or change the shape of the structure). This point causes a certain change (if necessary) i.e. the place is not just a measuring point. The effect of the separation point (its success) is measurable and the measurement results serve as a benchmark for the (a certain) performance of the preceding (upstream) process stages. The separation point can therefore serve as a control center. Finally, insofar as the separation point carries out the changes intended for it, it "deletes" the corresponding information in the processed material itself, so that after it there is no (more) information about the performance of the previous stages.

Claims (9)

Claims 1. A method for controlling a fiber processing system, which comprises a sequence of processing stages (120, 122, 124, 126, 128, 130, 132, 136, 138, 140, 142) in order to deliver fiber material as a predetermined fiber structure , the properties of this structure being able to be influenced by suitable, selectively adaptable processing of the fiber material in the course of the system, and in at least one intermediate stage (130, 136, 138) a detectable property of the intermediate product of this stage by the controlled processing within the stage is determined and thereby a corresponding property of the structure is significantly influenced, because no subsequent stage has a controlled effect on this property, characterized in that in this intermediate stage (130, 136, 138) a signal (KFA) is obtained, which of the detectable Property corresponds in such a way that it precedes the behavior of this intermediate stage levels corresponding to this property. 15 5 10th 15 20th 25th 30th 35 40 45 50 55 CH 685 247 A5 2. The method according to claim 1, characterized in that the signal for controlling or regulating is used by at least one preceding processing stage influencing this property. 3. The method according to claim 1, wherein the fiber processing system comprises a combing (52) and a processing line feeding the combing (42-50), characterized in that a signal is obtained which indicates the short fiber content (KFA) of the combing (52) supplied material and that this signal is used to control or regulate the processing line (42-50). 4. The method according to claim 1, wherein the fiber processing system is provided with at least one regulating drafting device (Fig. 7; 11) before spinning, characterized in that a guide signal is obtained from this drafting device (Fig. 7; 11) which corresponds to the uniformity of the Intermediate products corresponds to the processing stages upstream of the drafting system. 5. Fiber processing system for performing the method according to claim 1, characterized in that means for obtaining a signal are present in this intermediate stage, which corresponds to the determinable property in such a way that it corresponds to the behavior of the stages preceding this intermediate stage with respect to this property. 6. System according to claim 5, characterized in that control or regulating means (PLR, R2, R3) are present to evaluate the signal and to control or regulate at least one preceding processing stage influencing this property. 7. Plant according to claim 5 or 6, characterized in that the signal from the combing machine (1) is obtained. 8. Plant according to claim 5 or 6, characterized in that the signal from a regulating drafting device (Fig. 11; 11) is obtained. 9. Plant according to claim 5, wherein the intermediate stage (130, 136, 138) with a regulating drafting device (Fig. 11) for fiber assemblies (216) with at least one warping field (211, 212), a controllable or regulatable drive system for determining the amount of warpage in the warpage, a programmable controller for the drive system (207.1, 207.2) and at least one sensor (209.1) for determining the fiber mass per length unit at a measuring point, characterized in that a warp-determining signal is stored over a predetermined period and off the stored values are used to obtain information for adapting the drafting system and / or for assessing the quality of the fiber bundles. 16