EP0311831A1 - Control of working stages of a fibre processing plant - Google Patents

Abstract

In a fiber processing plant, a stage (UF) runs discontinuously (stop / go operation), while a stage (K) downstream of it runs continuously or quasi-continuously. The ratio of runtime / lactation of the discontinuously running stage is controlled or regulated depending on the production of the downstream stage.

Description

This invention relates to a control for processing stages in a fiber processing plant. For example, the plant is part of a spinning mill for the production of staple fiber yarns, but the invention is not limited to this application.

State of the art

The automatic bale removal by means of a reciprocating bale removal unit has now been well introduced in the short-staple spinning mill, and various suggestions for controlling the process have meanwhile been presented, in particular a suggestion regarding optimization (European Patent No. 93235 = US 4566152).

These horsepower propose a process according to which the bale removal unit runs in the so-called stop / go mode and the removal depth or the driving speed speed of the unit is controllable in order to maintain an "optimal" ratio of running time / lactation as continuously as possible. Switching the bale removal on and off is carried out on the basis of control signals which are obtained from the next processing stage.

It is also known to obtain control signals for bale removal from a processing stage at the end of the blowroom line (e.g. from the card) (DOS 3513295). In this case, the control signals are used to control the driving speed of the removal unit. If a discontinuous (stop / go) operating mode is provided, the runtime / lactation ratio should also be "optimized" here (col. 3, lines 31 to 38 of the DOS).

It is also known to determine the material supply from the bale removal to the first cleaning stage by means of a control signal obtained from the card (DPS 3151697), with the aim of avoiding “downtimes of the blowroom machines” (col. 3, lines 2/3 of the DPS) or "let the cleaning machines run almost continuously" (col. 3, lines 10/11).

However, it is also known to operate the blow room line continuously, control signals for the various machines in the line being obtained from the cards (Melliand Textilberichte, 2/1987, pages 77 to 83, in particular page 81 - see DOS 3237864 and US 4535511 = DOS 3244619).

Finally, it is also known to control the fiber supply to the card itself based on the number of cards produced - see DOS 3442942. Another The use of this principle is described in our CH patent application no. 3109/87.

As mentioned in the latter, unpublished patent application, a change in fiber processing is generally undesirable because it can lead to quality changes in the end product (yarn). At best, the state of the art listed does not contain a control concept for keeping this fiber processing constant - in certain fills (e.g. EU 93235) a change in fiber processing is the basis of the control concept.

The present invention cannot completely rule out changes in fiber processing, but can significantly reduce them, and is in any case designed in such a way that changes in fiber processing are normally only required within narrowly defined limits.

The invention

The invention provides a fiber processing installation which consists of a plurality of fiber processing stages, fibers to be processed being conveyed in sequence from stage to stage and at least one stage running in stop / go mode, while a stage downstream of it is a predetermined product (e.g. a sliver) continuously delivers. The "levels" are defined according to the technology and not according to the machines. A "stage" can therefore include a plurality of individual machines. For example, a carding stage could comprise between 6 and 20 individual machines. The delivered product (or the output) of a stage then comprises the production of all machines currently running in this stage.

The invention also provides for the determination of a target value for the ratio of runtime / lactation in said (upstream) stage, which is to run in stop / go mode. Monitoring means are also available to monitor the actual runtime / lactation ratio of this stage and to compare it with the predefined setpoint. In the event of a deviation of the actual ratio from the target ratio, the production of this stage, which remains constant during normal operation during the running time, can either be increased or decreased in order to adjust the actual ratio mentioned to the target ratio.

In this respect, the features of this invention are common to the statements in European patent specification 93235.

However, the present invention is characterized in that the setpoint is not fixed (as suggested in EU-PS 93235), but can be changed as a function of the production of the downstream stage (which is continuously producing in normal operation).

The system can be designed in such a way that a change in the output of the output stage is immediately reflected in a corresponding change in the target ratio of runtime / lactation in each upstream, discontinuous stage, the "corresponding change" being able to be determined individually for each upstream stage.

The named function can be determined so that the target ratio takes a theoretically optimal value (e.g. 90:10 - see EU-PS 93235) with full production of the downstream stage. The target ratio can then be reduced linearly depending on the reduction in the production of the downstream stage. The optimal adjustment function for a particular plant can be determined empirically and entered into the system, and where adjustment to multiple levels occurs, the adjustment function can vary from level to level.

The monitoring of the actual runtime / lactation ratio can be carried out according to the principles described in EU-PS 93235, and in the case of bale removal as an upstream stage, the production can also be changed as described in this European patent specification, i.e. by changing the removal depth or the driving speed of the removal unit. The invention can thus be easily integrated into existing systems, in which feedback circuits are provided between stages in order to regulate the ratio of the running time / idle time of the upstream stage according to predetermined states in the downstream stage (e.g. filling level in a memory).

The system is preferably controlled by a computer which monitors the production of the downstream stage and determines the target ratio for the upstream stage (s) accordingly. Control loops between upstream stages can also be implemented via the computer.

• Fig. 1 Eine Kopie von Fig. 4 unserer CH Patentanmel­dung No. 3109/87,
• Fig. 2 eine diagrammatische Darstellung einer Modi­fikation der Anordnung von Fig. 1, um sie ge­mäss dieser Erfindung auszuführen,
• Fig. 3 eine schematische Seitenansicht einer faser­verarbeitenden Wlage einer Kurzstapelspin­nerei,
• Fig. 4 eine schematische Ansicht von oben der glei­chen Anlage, zusammen mit Verbindungen zwi­schen den verschiedenen Stufen und einem Leit­rechner,
• Fig. 5 zeigt in Fig. 5a ein Schaltschema und in Fig. 5b ein Zeitdiagramm zur Erklärung der Regel­verbindungen in einer Anlage gemiss Fig. 4.

The invention is now based on only as Games listed versions are explained in more detail. It shows:

• Fig. 1 A copy of Fig. 4 of our CH patent application no. 3109/87,
• FIG. 2 is a diagrammatic illustration of a modification of the arrangement of FIG. 1 to implement it in accordance with this invention;
• 3 shows a schematic side view of a fiber-processing bed of a short-staple spinning mill,
• 4 shows a schematic view from above of the same system, together with connections between the different stages and a host computer,
• 5 shows a circuit diagram in FIG. 5a and a time diagram for explaining the control connections in a system according to FIG. 4 in FIG. 5b.

The description will initially focus on the system shown in full lines in Fig. 1. This comprises a feed machine S, a fan v, a feed channel K, two cards C1 and C2, each with a filling shaft (not indicated), a microprocessor control μp and a controllable drive A for the feed machine S. A measuring device M is in the channel K between the Fan V and the first card C1 installed to measure the static pressure. It delivers an output signal to the microprocessor µp. Each card C1 or C2 delivers a signal to the microprocessor µP to show whether this card is currently in operation or not. The microprocessor control µP supplies a control signal to the drive A of the food processor S.

The fan drive, not shown, cannot be controlled by the control µP. In operation, it runs at a constant speed n.

The control system should work together with the other elements in such a way that the filling chute of each card being produced remains "full" (within certain tolerances). As was shown in the CH Wmeldung 3109/87, the static pressure in the channel K at the measuring device M can represent the filling conditions. If the measured static pressure is outside a range determined by the processor µP, the supply is switched on (when the pressure drops) or switched off (when the pressure rises). The supply therefore runs in the so-called stop / go operating mode.

The control uP only switches the feed drive A on and off, in this example it has no influence on the speed of the drive, ie on the current production of the feed machine. This current production is predetermined for normal operation and kept constant, so that a constant quality (processing of the fibers) is achieved. The set production must be sufficient for the greatest possible "demand" from the connected cards. Normally a certain "overproduction" is set, so that when all connected cards produce as quickly as possible, there is an efficient relationship between the idle time and the running time of the food processor in stop / go mode, eg 90% running time to 10% standing time.

As is indicated in FIG. 1 by dashed lines, the control method described is not restricted to a simple system with only two cards. As is also mentioned in the CH patent application 3109/87, in the case of an unadjustable line, the current production of the dining machine S can be fixed or set during the assembly of the system. However, if the number of cards allocated to a food machine can be reduced, e.g. by actuating a release agent T (Fig. 1), a fixed production of the food machine S is not useful. As foreseen in the CH registration, the production should be adjusted to the number of cards allocated to the food machine, in order to enable an optimal ratio of runtime to breastfeeding for each given allocation.

There are, of course, various options for adapting the current production of the feed machine to the number of cards allocated to it. This production can, for example, be set manually on the machine itself, so that the µP control only has to perform an on / off function. The necessary adjustment could also be carried out by the control µP if the necessary information is communicated to it. If, for example, the line contains a separating means T, as indicated by dashed lines in FIG. 4, this separating means can also be connected to the control μP by a signal line, so that the control is informed of the currently "effective structure" of the line. In the example given, the separating agent T blocks the feed channel K between card C2 and a third card C3. If this release agent T is made ineffective, the card C3 can also be fed from the feed machine S via the channel F flakes.

In such an arrangement the average production of the feed machine must correspond to the total production of the cards allocated to this feed machine. The average production of the food machine depends on (a function of) the current production set and the ratio of running time / lactation.

Although the cards run "continuously", the overall production of the card is subject to fluctuations, e.g. can be provisionally turned off for any reason.

Since the instantaneous production of the food machine in FIG. 1 is fixed for normal operation (without changing the allocation), the ratio of runtime to lactation has to adapt in order to absorb fluctuations in the overall production of the cards. This is usually an uncontrolled procedure that does not always run smoothly. This invention provides control for such operations.

According to this proposal, the ratio of the running time / lactation of the feed machine S is to be monitored, as was already proposed in the EU PS 93235 for bale removal. Since the processor µP switches the drive A on and off, the processor can easily determine the running time (or downtime) of the food processor over a predetermined time interval, which equates (or enables) the determination of the ratio of running time / downtime for these intervals light, if it is desired to calculate the ratio yourself). This actual ratio is then compared with a target ratio and any deviations are determined. The current production of the feed machine is then adjusted (for example by changing the speed of the feed roller during its running time) in order to counter the deviation. The target ratio is not fixed (as in EU 93235), but is calculated by the processor depending on the number of producing cards. Possibilities for such a determination will be described below in connection with FIGS. 3 to 5. For the time being, the principle is briefly summarized using the diagram in FIG. 2.

In Fig. 2, the box Z represents the final stage (carding machine) of the line which is supplied by the upstream stage X, so that a material flow Y (from X to Z) takes place. This material flow is switched on and off depending on consumption via the feedback R.

The ratio runtime / lactation of stage X is determined and delivered as a signal via line L to a comparison means VM. A determining measure of the consumption is converted in stage Z into a signal representing a target ratio and delivered via line 1 to the comparison means VM.

Any deviations are determined by the means VM and forwarded as a signal e. The stage X evaluates the signal e so that a change in the current production of this stage takes place. However, the necessary change will be small (fine adjustment), because the level Z will be corresponding at this time less material is required via the feedback R - the invention facilitates the adaptation of stage X to the behavior of stage Z. The adaptation can thus be carried out relatively quickly, since the system is no longer dependent on "leveling off" on an uncontrolled runtime / lactation ratio . But it is also no longer tied to a "rigid"("optimized") ratio (as suggested in EU PS 93235), which means relatively large changes in fiber processing (with corresponding fluctuations in the quality of the end product).

However, the invention can also be used to control other upstream stages, as will now be explained in connection with the other figures.

The system shown schematically in Fig. 3 comprises 6 "stages" I to VI. This system corresponds to the fiber processing line of the short-staple spinning mill that is common today, from bale removal (level I) to carding (VI). The material (fibers or flakes) is conveyed pneumatically between the different stages, which is indicated by schematic pipelines (double arrows) in FIG. 3.

As an example, a line according to FIG. 3 is explained in somewhat more detail by references to corresponding machines of the filing company, but the invention is in no way restricted to the use of these particular machines. Level I can include a single "Unifloc" (Registered Trade Mark) machine and Level II can include a "single roller cleaner" machine. Level III can be a single "Unimix" (Registered Trade Mark) and stage IV include a fine opener of the type "unit cleaning machine" (EW).

Stage V comprises an ERM machine, together with a transport fan, not shown, to form a flake feed unit. The latter is used to feed flakes to a plurality of cards K, which together form stage VI, each card K being equipped with its own feed chute and the feed chutes being connected to a common feed duct extending from the stage V transport fan.

In normal operation, each card K runs continuously and delivers a continuous sliver (not shown). The customers of the cards are connected via a line 10 (FIG. 2) to a master computer LR, so that the computer is informed whether each card is currently in operation or not. Only three cards K are shown in FIG. 2, but the overall system can of course comprise a much larger number of these machines, the master computer LR monitoring the operating state of each individual card.

A pressure sensor 14 reacts to the static pressure in the feed channel and delivers a corresponding signal via line 12 to the computer LR. As already described, the computer sends a corresponding signal to the flake feed unit FS in order to switch the flake feed on or off. The supply unit is therefore connected to the computer LR by a line 16.

The flake feed unit also has a filling shaft, which material from the ERM machine in stage IV receives. A level monitor (not shown) installed in this shaft is connected to the computer by a line 18 so that the latter can switch the delivery from the ERM machine on or off via line 20. A similar level monitoring (not shown) of the ERM machine gives a signal via line 22 to the computer for controlling the delivery of the mixing machine UM via line 24.

The storage box of the mixing machine UM is also equipped with a level monitor (not shown) which emits a signal via line 26 to the computer LR. Accordingly, the computer sends signals via a line 28 to the traction motor (not shown) of the bale removal unit in order to switch the bale removal on or off.

It will be clear from this description that stages I, III, IV and V run discontinuously (in stop / go mode) and that each of these upstream stages is connected to a downstream stage by a feedback circuit. As indicated schematically in Fig. 5a, this control loop consists of the material flow MF itself, the level monitoring NU of the downstream stage, the signal connection with the host computer LR, the drive motor AM, the upstream stage and the signal connection between the computer and the drive motor. Such control loops are of course well-known prior art.

According to this invention, the ratio runtime / lactation of at least one upstream stage, preferably stage I, is to be monitored by the host computer LR and compared with a target value. For this purpose, a signal from the drive motor AM (FIG. 5a) is sent to the computer via the line 30 and there with a clock signal from a clock generator TG is subjected to an AND operation (indicated schematically by an AND gate), and the resultant result Signal is delivered to a counter Z. The latter also receives the clock signal from the clock generator TG and uses the latter signal to define predetermined time periods T (FIG. 5B) of the same length. Within each time period T, the counter Z either sums up the time intervals t during which the drive motor AM is running or the smaller, intermediate pauses. From these values, the counter Z calculates an average value for the actual runtime / lactation ratio of the corresponding upstream stage.

The output signal of the counter Z which represents the actual ratio is supplied to a comparison device G and is compared there with a signal which represents a setpoint value. A signal representing any deviations is converted by the computer LR into a corresponding control signal in order to change the effective production of the upstream machine accordingly. Assuming that the computer LR thereby controls the production of stage I (bale removal machine), the desired production change can be carried out via one, the other or both of two setting options, namely by setting the removal depth or setting the driving speed of the unit. Corresponding signals can be sent via line 28 (driving speed) to the drive motor of the overall unit and / or via line 328 to a height adjustment device (not shown) for the bale removal member of the unit (see EU-PS 93235 and US-PS 4,660,257) can be supplied.

The signal representing the setpoint value, which is supplied to the device G, must be generated by the master computer LR as a function of signals received via the line 10. In the preferred arrangement, the setpoint is selected step by step depending on the number of cards currently running, it is not necessarily the absolute number that is important, but only the proportion of running cards compared to the maximum number. For example, if all cards are running, the setpoint for the runtime / downtime ratio of the bale removal machine can be set to 90:10. If only two thirds of the cards are running, the target ratio for the bale removal machine can be reduced to 60:40 - a linear adjustment of the ratio to the reduced number of running cards.

Each intermediate stage can also be monitored individually by the master computer LR. In the intermediate stages, there is normally only one setting option if the stop / go ratio has to be adjusted, namely a change in the speed of the feed rollers of the flake or fiber delivery unit.

Possible changes are shown schematically in FIG. 5b. In normal operation, with full production in stage VI (all cards K run), the bale removal machine runs within a period T over five intervals t, which are drawn with full lines (such a regular run is of course highly unlikely in practice, but only serves Explanation of the principle). If the production of one or more cards fails, the duration of each inter valls are reduced in the given time period T (Δ), which was indicated by dashed, vertical lines.

If the effective production of the upstream stage (an average value over the time period T) is not sufficient to keep the filling level in the downstream stage within predetermined limits, the maximum production of the upstream stage must be increased (constantly over each time interval), in order to do so to comply with the newly set target ratio for the running time / lactation. Such an increase is indicated by i between the first and second time period in FIG. 5b, the duration Δ of each interval in the second time period corresponding to the duration of the reduced intervals Δ (indicated by dashed lines) of the first time period.

From Fig. 3 it will be seen that the production of the first continuously running stage (in the given example of the carding machine) determines the target value for the ratio of running time to lactation of at least one and preferably all upstream, discontinuously running stages. However, these are not necessarily all upstream stages. The mono-roller cleaner (stage II in Fig. 3) runs continuously, although the two stages I and III run discontinuously. In this case, stage II plays no role in the "rule chain", which it simply skips by connecting the storage box - computer - bale opener.

The invention is not restricted to the use of a production signal from the card to control the upstream machines. The true one However, the production signal should be continuously available and should represent a reliable measure of the actual production of the line. The first stage of the line that can meet these conditions is preferably chosen as the determining stage for the control of the upstream machines. In short-staple spinning, the conditions mentioned can usually only be met in the carding machine.

Normally the set production of each individual card will be the same. To determine the current production of the card, it is then sufficient to tell the computer whether each individual card is running or not. If the production values for the individual cards are set individually, the computer must not only be informed whether a specific card is running, but also which production has currently been set for this card.

The circuit shown in FIG. 5a for monitoring the actual ratio of runtime to lactation is not essential. Alternative proposals have already been listed in EU PS 93235. The optimal time period (T) for monitoring can be determined empirically and then preprogrammed.

The term “plant” in this context comprises a plurality of processing stages which have been linked together in a processing line by suitable fiber transport means and / or control devices. The fibers to be processed pass through the stages in a predetermined order. The fiber transport means is preferably pneumatic, but not necessarily. In any case, the transport process runs automatically, ie without On gripped the operator. It also normally runs continuously, ie this is not a batch transport.

According to the suggestions already described, the "fine adjustment" is to be carried out by changing the production, which usually means a change in quality. In our newly filed Swiss patent application no. (Title: production control) we propose a procedure according to which the total production of a processing stage or processing machine can be changed, but the specific production (production per unit length of processing width) can be kept constant, which means constant quality . The method proposed in this new patent application can advantageously be combined with the present invention.

Claims (5)

1. A fiber processing system with a plurality of processing stages, which are connected to one another by automatic (preferably pneumatic) conveying means for conveying the fibers to be processed in a predetermined sequence, with at least one stage running discontinuously (in stop / go mode) and with one Control for monitoring the actual ratio of runtime / lactation to at least the discontinuously running level mentioned,
characterized,
that means are present for generating a signal which represents the total production of a stage connected downstream of the stage and that the controller reacts to this signal to form a setpoint for the ratio of the running time / still time of the stage which is running discontinuously. 2. An installation according to claim 1,
characterized,
that the downstream stage mentioned is the carding machine. 3. An installation according to claim 1 or 2,
characterized,
that the discontinuously running stage carries out the fiber feeding to the cards. 4. A system according to claim 1 or 2, characterized in that
that the discontinuous stage mentioned carries out the bale removal. 5. An installation according to claim 1, 2 or 3,
characterized,
that the control system monitors the actual ratio of runtime / lactation of each discontinuously running stage.

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