EP0803596B1 - Minimum value determining regulation method at a drawing or carding machine - Google Patents

Description

The technical field of the invention is the adjustment of a Regulating section in the textile industry, which has the task Tapes of textile fiber (fiber fleece) to stretch and multiple times to bring about an evenness by stretching.

An example of a regulating path is described in the generic EP 176 661 B1 , distinguishing between a short-staple spinning mill and a long-staple spinning mill, the regulating stretches being described in the long-staple spinning mill as working according to the principle of the open control loop (pilot control). The electronic control system RSB 851 from Rieter Ingolstadt AG , which has been accessible to the public since August 1990, also works according to the principle of pre-control, in which the strength of the incoming fiber slivers (total sliver made up of several individual slivers) is mechanically scanned (groove roller) at the entrance to the machine / Feeler roller) is continuously measured and converted into electrical signals. The measured values are fed to an electronic memory with a variable delay. By changing the deceleration of the RSB 851, the change in warpage between the center roller and the delivery roller of the line takes place at exactly the moment when the piece of tape previously measured by the pair of feeler rollers with changed thickness is in the warping point. The change in default therefore takes effect in the main default field at the point in time at which it is required. The delay in the measured value means that the corresponding sliver thickness in the sliver can run through the distance between the pair of input feeler rollers and the place of warpage. When the strip thickness reaches the fictitious warp point in the warp field, the corresponding measured value is released by the electronic memory. This distance between the measuring location of the pair of sensing rollers and the location of the delay is called the control starting point R. Once the control point of use has been reached, an actuating action takes place on the control motor depending on the measured value.

In the past, the rule of action was also Called "runtime T". Since the scanning system for obtaining Measured values with the RSB 851 but independent of the The speed of the sliver is always a constant Scanning sliver sections is the term standard starting point sensible.

The setting of the pilot control and thus the electronic Memory is not without problems and requires prior Commissioning a time-consuming adjustment. To control the The control parameters set could be changed at intervals from Operator a so-called tape test can be prepared (described in the operating instructions, route RSB 851 (4135), SB 851 (4131) "Rieter Spinning Systems" from Schubert & Salzer Maschinenfabrik AG from August 1990, section 4.5.6, pages 40 - 42). That is why an attempt was made to change the parameters of the feedforward control, consisting of the standard point of use and a reinforcement on-line adjust, with the in a constant control movement Pre-control parameters based on measured values at the output of the Drafting system can be influenced. This kind of setting lets Although the time-consuming tape test is eliminated, this type of Adjustment also causes a continuous unwanted Control movement with regard to the parameters of the pilot control (the electronic regulation system). This constant regulatory movement causes unrest in the control. Machine internal Influences of defects (e.g. damaged rollers, slip of the rollers, Play in the transmission etc.) can affect the sliver, although they are not included as errors in the incoming sliver were. But only influences of the incoming sliver are desired and these can be in the expiring, stretched Sliver not easily from the machine's internal Influences are separated.

The object of the invention is therefore to bring about the acceleration of the optimization as described in the publication mentioned at the outset, but not to design the optimization in such a way that it creates an inherent unrest in the route regulation.

The starting point and knowledge of the invention is the online adaptation to leave the parameters of regulation and to go over the parameters of regulation in one pre-operational test or adjustment on the line or card to be determined and left largely unchanged in operation (Claim 1). In the pre-operational setting up a A plurality of measured values determined, which is a quality characteristic Size, regarding the drawn sliver, represent. On the basis of these several measured values, a Function course determines, the minimum of which value that best adapts regulation to that current sliver promises. The multiple readings that be recorded and with which the function history is determined at a different setting of regulation measured so that for the definition of function course to be evaluated an incrementally changing Parameters, e.g. the standard operating point of the "electronic Memory ", with each of its increment values one of the Measured values must be assigned.

On the basis of the minimum value determination, the Most favorable value of a parameter in the pre-operational test run be determined. This value is determined according to the philosophy of Invention either directly or after going through one Plausibility check or after suggestions to one Users and upon confirmation in the regulation taken over in order to keep the company constant over the long term Worth staying. According to the invention, this avoids the once approved setting values for regulation to change constantly and at the same time run the risk of changes due to disturbance variables that occur for the sliver are not specific.

Good setting values are therefore retained, not on-line constantly changing.

The CV value can be used as a quality characteristic be measured as a continuously measured quantity Amplitude evaluation of the sliver thickness in the selective Characterized length range of delivered sliver. On Microprocessor can be used for this CV value to determine a certain tape length and as a quality characteristic Measured value for one of the incremental changing parameters in a memory area (Claim 8) before the minimum value search is carried out.

In the same way, another parameter of regulation pre-operational optimization, namely the gain K the pilot control.

One and the other parameters can be changed one after the other be optimized (claim 2, claim 3); not each optimized parameter advantageously changes its value during the Measured value recording for the minimum value function not.

If a better quality of the incoming sliver (at the input probe roller pair) can Distance of the measured values for the quality-defining variable be reduced (claim 11). This will make it recognizable of the minimum improved because the quality of the incoming sliver is only a weak one Minimum of the CV measured values above the respective incremental shows adjusted parameters of the regulation. The minimum becomes too flat, a differentiation or an approximate method can be used.

In the long term, good quality can take about one Jug filling of the hidden tape.

Is one of the Parameters quasi-continuously (incrementally in small Steps, but continuously in the long term), so can a certain time after each incremental step pass and the tape through the track or teasel pass through without the quality-indicative size is measured or their measured values for the function for determination of the minimum are taken into account (claim 12).

The equidistant values for the Standard starting point at the distance between the pair of input rollers and default point; so they are in one Unit of length must be standardized.

The proposals according to the invention work faster and at the same time more precise, while avoiding that non-sliver specific Influences on the adaptation of regulation influence to take. The minimum value search is an algorithmic one Calculator work to be done easily. As a result will give a user one or more value (s) for the setting proposed by the regulation, which they then use or can discard.

A major advantage of measuring the tape before depositing it lies in the fact that errors caused by the filing no longer have any influence have the optimization, like that with a CV value determination was the case in the textile laboratory or the case with the "belt test" was in which after the sliver was placed in the jug stretched sliver was taken out and in sections was broken down into sorts of different tape lengths, to make statements about the quality of the Preserve regulation.

Figur 1

ist eine schematische Darstellung des Streckbereichs zwischen einem Mittenwalzenpaar M und einem Lieferwalzenpaar L mit einem dazwischenliegenden Verzugsfeld VF, in dem das Faserband 20 mehrfach verstreckt wird. Erkennbar ist die in Form von Blockschaltbildern vorgesehene Regulierung mit Vorsteuerung 10 sowie einer Steuerung 11, die Regeleinsatzpunkt R und Verstärkung K der Strecken-Vorsteuerung 10 verändert.

Figur 2a

ist eine Darstellung der Minimalwert-Suche für den einen Parameter (Regeleinsatzpunkt).

Figur 2b

ist eine flacher verlaufende Qualitätsfunktion b mit einem Minimalwert b_min für die Bestimmung der optimalen Verstärkung K₀ der Regulierung 10.

The invention (s) are explained and supplemented below using several exemplary embodiments.

Figure 1

is a schematic representation of the stretching area between a pair of center rolls M and a pair of delivery rolls L with an intermediate warping area VF, in which the sliver 20 is stretched several times. The regulation provided in the form of block diagrams with pilot control 10 and a controller 11, which changes the control starting point R and gain K of the route pilot control 10, can be seen.

Figure 2a

is a representation of the minimum value search for the one parameter (control point).

Figure 2b

is a flatter quality function b with a minimum value b _min for determining the optimal gain K _{0 of} the regulation 10.

Mechanical and electronic elements are shown schematically in FIG. 1 in order to explain their interaction in terms of control and regulation technology. The aim of the control and regulation is to know the warping point 21 in the warping field VF, in which there is a strong fiber warping of the incoming sliver 20, as precisely as possible and to ensure that it is from a thickness measurement signal d ₀ (n), that comes from a pair of input rollers, which is upstream of the center rollers M and possibly these upstream inlet rollers, is influenced via a channel or pilot control 10 in such a way that a change in distortion occurs by changing the speed of the center rollers M precisely when a changed thickness d ₀ , which was previously measured, is in the delay point 21.

The sliver 20 is composed of several individual strands, which are brought together in front of the input feeler rollers, not shown here, and whose thickness is determined together. Depending on the quality of the sliver and depending on whether a sliver is thicker or thinner or possibly torn, the thickness of the band 20 changes, the warping in the warping field VF must change accordingly, which is achieved via a pilot control 10. With this feedforward control 10, the speed v _{0 of} the center rolls M is changed while the speed of the delivery rolls L remains constant, which in the example shown here has about six times the delivery speed when six fiber slivers are brought together to form a strand 20 at the entrance. A corresponding channel for the speed v ₀ over 1/6 of the stationary speed 6 · v _{0 of} the delivery rollers L can also be integrated in the pilot control 10.

The mechanical part ends behind the delivery rollers L. Calender rolls F for drawing off the drawn sliver 20a. As A jug can serve as storage. Behind the exit of the Delivery rollers L and before depositing a measurement on stretched sliver made. This measurement concerns in The example shown here is the pair of calender rolls with which the Quality of the sliver 20a measured after stretching can be. It is suitable as a quality characteristic the CV% value, which is directly during the transport of the sliver can be measured (see publication by Rieter Link, Issue 2/95, pages 14 and 15). The in length discrete Samples available (values) are represented by a calculation over a defined length as a CV value provided. The CV value is an evaluation variable of a Control Panel 11.

The controller 11 receives an optimization command "OPT" and generates commands for the incrementation of Standard operating point R and gain K.

In a setting or test run, sliver 20 is stretched between center rolls M and delivery rolls L and conveyed into a can by a depositing device. Separate measurements or examinations of the deposited tape 20a do not need to take place, however, since the CV value measurement is provided with the measuring device 12. In response to an "OPT" command, the control sets an arbitrary, usually a suspected, first value R _min , previously determined from empirical values (eg table), for the control starting point in a channel of the pilot control 10. The empirical value from the material table can be entered using a keyboard. However, a knowledge memory integrated in the control 11 can also provide the empirical value from a stored table on demand. After running through a certain amount of tape, which should be just long enough that a clear CV value can be calculated from it, a CV value is recorded, which is designated CV ₁ in FIG. 2a . This measured value from the measuring device 12 is written into a memory area of the controller 11. The control point R of the pilot control 10 set first is then changed by at least one increment. Again, the tape 20 will run for a certain time until the corresponding CV ₂ value is stored by the controller 11 in the same memory area.

In the same way, the control starting point is incremented further and a CV ₃ value is measured again until a reasonable number (approx. 5, 10 or 15 measured values) is available, oriented between a minimum control starting point R _min and a maximum control starting point R _max . The function a (R) thus formed in the memory area of the controller 11 can be examined to a minimum by evaluation methods, which can be assumed at R ₀ in the case of the function shown in FIG. 2a, where the minimum CV _min is. The position recognized as the minimum CV _{min of} the function a, also denoted by a _m , defines the best setting for the control starting point R of the pilot control 10, with the gain factor K initially kept constant in the channel for the thickness measurement signal d ₀ (n).

Once a minimum a _m for the setting of the control point of use of the electronic memory of the pilot control 10 has been determined, this control point of use can be transferred to the electronic memory of the pilot control 10, if necessary after having passed a plausibility check and confirmed by the operator. The same test and setting run is then carried out for determining a function b (k) shown in FIG. 2b, this quality function being dependent on the changing gain K. Practice has shown that this function is generally flatter and has a less pronounced minimum CV _min = b _m . If the evaluation of the pure measured values CV _i , i = 1 ... n, where n should be between 5 and 10, does not lead to a usable result for K ₀ as the best value for the gain and R ₀ as the best value for the control point of application The one or the other curve can also be differentiated by the program control in the control 11 in order to make the minimum clearer. The differentiation means that it is not a minimum but a zero crossing of the differentiated function that must be determined, which is possible with the measurement functions a (R) and b (K) running to a certain extent.

If, in accordance with the above procedure, best values have been found for R ₀ and K ₀ , these values can be adopted directly in the pilot control 10 before the actual production operation of the line is started. The determined values for R and K can, however, also first be proposed to the operator who, if explicitly requested, accepts them in the pilot control 10 by actuating an input element (key).

To ensure that not due to accidental influences wrong value for R and K for the actual one Production operations can be discontinued Plausibility checks are provided for a specific Quality of sliver 20 a predefined Admissibility window between two limit values then the best value determined by the minimum search check whether it is in this window.

The parameter set for the production plant for the Standard operating point and for the amplification of the pilot control 10 is no longer changed during production, it rather remain constant. At large intervals or at Guess that these parameters are no longer the best setting for the route, a new minimum value search in be made on the route for which the Manufacturing will be interrupted briefly.

On the basis of some exemplary numerical values, it can be measured which exact setting for the control starting point R is possible with the optimization that searches for the minimum value. Assuming a distance of about one meter (1m) between the measuring point and the delay point, the control point R to be set corresponds to the distance or distance that a piece of tape needs from the measuring point to the delay point. If the optimization is immediately based on distances, the changes in the control point of application can be 3 mm, between two measured values CV ₁ and CV ₂ . The distances to the other measured values can also be the same in order to obtain a path-constant scanning. Only when the CV value has been measured with a sufficiently large number of individual measurements is a secure value available for storage as a quality measurement of the functions a (R) and b (K).

With this procedure, you can continuously the quality functions a (R) and b (K) without Stopping and adjusting the belt can be determined. The The process is so fast, easy and user-friendly for the actual production operation with the best possible adjusted parameters very quiet in terms of control technology.

The hardware or software implementation in the controller 11 for changing the control starting point R of the pilot control 10 is implemented with a variable memory length. Measured values that originate from the thickness measurement d ₀ (n), which represent instantaneous values of the strip thickness currently passing through the pair of input rollers, are continuously written into these memory cells arranged in the memory.

The memory in which the length-discrete measured values mentioned stored, has a changing length or - in Shown in a circle - an inflating and reducing Scope if you have equal distance of the memory values on the Circumference of the circle. In the real memory area - linear and arranged one after the other - the measured values are specified of a pointer value (pointer) stored in the memory and on read in the same place. The delay between two Read-write cycles for a memory cell correspond to the path from the measuring point to the delay point between the Center rollers and the delivery rollers (standard operating point). The The beginning and end of the memory are therefore at the same Job.

At the described registration point, the old value is read first, which now specifies the thickness that is in the delay point, and then the new value is stored as the thickness value that has just been measured via the pair of tas rolls with the time-discrete value d ₀ (n). The old value corresponds to the previous cycle, the new value is that of the current cycle.

The memory length does not change continuously. It will nor does it need two pointers, one of which is the pointer Place of registration and the other pointer the place of Reading defined.

Claims (13)

1. Process for the direct determination of setting values for point of autolevelling application and/or amplification (R, K) of a draw frame or carder whose fibre sliver drafting can be adjusted, where the control of the adjustable draw-frame or carder has at least one pilot control (10) in order to modify the drafting of the fibre sliver (20), characterised in that

   a) through several measured values (CV₁, CV₂, CV₃) of a quality-characterising magnitude such as CV value, a function (a, b) is determined, the minimum (a_m, b_m) of which results in an optimised parameter such as point of autolevelling application or amplification (R_o, K_o) for the control (10) of a draw frame or carder;

   b) the optimised parameter is determined in a pre-operational testing or setting run of the draw frame or carder and remains substantially unchanged in operation.
2. Process as in claim 1, in which the point of autolevelling application (R_o) and amplification (K_o) of the pilot control (10) are optimised in the setting run of the draw frame or carder, whereby the other value remains unchanged during the optimisation of the one value.
3. Process as in claim 2, in which the point of autolevelling application (R_o) is again optimised after the optimisation of the amplification (K_o).
4. Process as in claim 3 which is repeated until no detectable change in the parameters to be optimised takes place.
5. Process as in one of the preceding claims, in which the optimised parameters (R_o, K_o) of the control are proposed to the user before beginning of production operation to be accepted as parameters of the pilot control (10) or which are set automatically and in particular undergo a plausibility control before.
6. Process as in one of the preceding claims, in which the just optimised parameter is integrated directly into the control before the optimisation of the next or other parameter.
7. Process as in one of the preceding claims, in which the range in which the quality-characterising magnitude (CV) is examined for a minimum (a_m, b_m) is small as compared to the possible adjustment range of the parameter.
8. Process as in one of the preceding claims, in which equidistant testing values are stored in a memory area before computing the location of the minimum of the magnitude (CV) which characterises the quality.
9. Process as in claim 8, in which several meters of fibre sliver are conveyed through the draw frame or carder for each testing value until the on-line quality measuring device (12) is able to supply a reliable measured value (CV).
10. Process as in one of the preceding claims, in which the quality-characterising magnitude is measured between the delivery roller (L) and the place of deposit.
11. Process as in one of the preceding claims, whereby the interval between the measured values (CV) is lowered at an input scanning roller pair upon recognition of long-term better quality of the fibre sliver so that the minimum (a_m, b_m) may be more clearly recognised.
12. Process as in one of the preceding claims in which the pre-operational testing run of the draw-frame or carder is continuous and a time span is inserted between each new adjustment of the applicable parameter (R, K) of the control (10) in which the quality-characterising magnitude (CV) is not measured or where the measuring result is at least not taken into account.
13. Process as in one of the preceding claims in which the equidistance of the measured values (CV) of the quality-measuring device relates to the fibre sliver or to time.

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