EP0617149A1 - Method for evening textile fibre bands - Google Patents

Abstract

To equalise textile sliver material at a drawing station, with separately driven sliver feed and take-off, the opening sliver mass (EM) is measured in freely selected steps by an absolute value transmitter (4), independently of the sliver speed and the measuring values. Each measured value (IW/EM) has an absolute lie together with a reaction point (SW/R). Both values (IW/EM, SW/R) are stored together in memory (S). The actual value (IW/EM) is interrogated at its lie in a freely selected point (R), to be used as a rotary speed nominal value (SW/D) for the motor (M1) through a frequency setter (fN). A cross section of the sliver is pref. formed from a freely selected number of actual measurements (IW/EM), to be stored in memory (S) with a related reaction point (SW/R).

Description

The invention relates to a method for equalizing textile fiber tapes on textile machines in textile preparation.
The leveling of a textile sliver is achieved by measuring the sliver thickness and corresponding changes in the drive speeds in the main draft zone.
Various methods and devices are already known for this.
The method which has been known for the longest time is to detect the strip mass fed to a stretching field by scanning by means of pressing and to derive a change in the feed speed therefrom. The fluctuation in thickness resulting from tape unevenness is passed on as a manipulated variable.
The distance between the measuring point and the effective point is bridged by means of a delay element.
The disadvantage of this method is that only the detection and influencing of thickness fluctuations is ensured compared to a predetermined initial position. A drift of the delivered tape mass is neither recorded nor can it be influenced.
Since the method is linked to a mechanical device, the inertia of the individual elements acts. This is particularly troublesome at high belt speeds.

From DE 3622584 A1, a method using an electronic control loop is known for fiber band equalization. The incoming total tape mass is detected by a measuring element and immediately converted into an electronic signal.
The method is based on a drive division into a control motor and a main motor. The main motor has the primary function of specifying the basic speed of the machine by means of a speed sensor. A nominal value is applied to the motor on the input side, and a manipulated variable is determined in a computer as a function of time from a control measurement on the delivery side. This allows the correction of the delay to be calculated.
The disadvantage here is that a constant switchover of the entire control between setpoint specification and manipulated value change is brought about by a clock generator; the two signals are subordinated. The manipulated variable can only be generated primarily and is not permanently available. The switchovers are dependent on the delivery speed and thus have a negative impact on the influenceable correction length of the strip irregularities in the short-wave range.
All known methods and devices for uniformizing a sliver have the disadvantages of inertia and wear of mechanical transmission elements.
Electronic control loops have the decisive disadvantage that deviations measured after the stretching field are used as control signals for the fiber sliver being fed in, and thus a discrepancy arises between the measuring point and the effective point.

The object of the invention is to carry out the homogenization of textile fiber tapes in a drafting system in such a way that the measured tape unevenness is immediately and exactly compensated for, that no pieces of fiber tape pass the drafting system unbalanced and without having to check the result in a downstream measuring device.
According to the invention, the object is achieved in that the input tape mass is measured independently of the tape speed and the size of the measured value by means of absolute value transmitters in freely selectable steps, that each measured value is assigned its absolute position as a reaction point, that these two values are stored in a memory as a common pair of values be that the actual value of the input band mass is called up when the assigned reaction point is reached and is output to the motor as a speed setpoint via a frequency controller. The absolute position of the strip unevenness is clearly defined by the same strip speed at the measuring location and in the stretching field. The processor recognizes the actual value of the input belt mass from the value of its assigned absolute position and brings the setpoint for output to the motor and the terminal, this setpoint corresponding to the speed currently required and the change in distortion associated with the unevenness of the hand.
It is optionally possible to form an average from a freely selectable number of measured values and to store this average value coupled with the value of an absolute position as a reaction point in the memory.
The motor speed of the tape feed drive changes, regardless of the absolute size of the measuring steps, whenever the measuring point or the beginning of the respective measuring section reaches the reaction point.

The position of the reaction point and thus the distance to be covered from the measuring point to the reaction point is automatically determined by the processor for different slivers according to the average fiber length entered at the terminal. To determine the absolute average sliver mass at the entrance, a length of freely selectable test sliver is run at the start of the processing of a new sliver type, from which the average sliver mass at the outlet is determined externally and entered into the processor via the terminal, and the processor automatically sets the basic delay in this regard corrected that the required storage tape mass is observed.

To clarify the concern of the present invention, the special features are to be described in more detail using an exemplary embodiment with associated drawings.

Fig. 1

Verfahrensschema - Bandmassesteuerung

Fig. 2

Schema der Werterfassung, Lagezuordnung und Auswertung

An einer Strecke befindet sich, wie in Fig. 1 dargestellt, auf der Bandzuführseite ein Antriebsmotor M1, der ein mitlaufendes Meßwalzenpaar 1, eine Meßvorrichtung 4 sowie den Zuführbereich 2 antreibt. Ein weiterer Motor M 2 treibt die Streckwerkswalzen 3 nach der Verzugszone an. Am Meßwalzenpaar 1 ist ein Geber 4, vorzugsweise ein Absolutwertgeber, zur Meßwerterfassung des Istwertes der Eingangsbandnasse IW/EM angeordnet.Show it

Fig. 1

Process scheme - tape measure control

Fig. 2

Scheme of value recording, location assignment and evaluation

As shown in FIG. 1, a drive motor M1, which drives a pair of rotating measuring rolls 1, a measuring device 4 and the feed area 2, is located on one line, as shown in FIG. 1. Another motor M 2 drives the drafting rollers 3 after the draft zone. An encoder 4, preferably an absolute encoder, is arranged on the pair of measuring rollers 1 for recording the measured value of the actual value of the input band wet IW / EM.

), wird entsprechend der gemessenen Abweichung der Banddicke von der durchschnittlichen Banddicke der Sollwert SW/D über den Frequenzsteller fN an den Motor M 1 und der Wert SW/AT an das Ausgabeterminal AT ausgegeben.
Damit wird die Drehzahl des Eingangsmotors M1 so verändert, daß die momentane Ungleichmäßigkeit des Bandes in der Verzugszone ausgeglichen wird.
Durch die absolute Zeitunabhängigkeit der Bandmassesteuerung, ihre Wirkung wird nur durch den zurückgelegten Weg der Achse des Eingangsmotors M1 bestimmt, kann die Zeit tR zwischen Messen des Istwertes IW/EM am Meßort MO und der Ausgabe des Sollwertes SW/D stets unterschiedlich sein.
Das Einschreiben von Istwert Meßpaaren IW/EM mit der zugehörigen Lage des Reaktionspunktes SW/R und die Ausgabe von Sollwerten SW/D sind zwei unterschiedliche Vorgänge, die nicht zwangsweise miteinander gekoppelt sind, sondern lediglich den gleichen Speicher S benutzen. Das Einschreiben von neuen Wertpaaren IW/EM/SW/R in den Speicher bewirkt nicht automatisch die Ausgabe eines Sollwertes SW/D.As shown in FIG. 2, the measured actual value IW / EW is entered into the memory S and coupled with the value of the absolute position SW / R of the reaction point R, which results from the distance lR to be covered.
The actual value acquisition IW / EM can take place at any intervals x.
The processor P constantly checks the reaction points SW / R assigned to the actual values IW / EM by comparing them with the actual value IW / R to determine whether a pair of values IW / EM // SW / R has reached the reaction point R. Is that the case ( $\text{IW / R = SW / R}$

), the desired value SW / D is output to the motor M 1 and the value SW / AT to the output terminal AT according to the measured deviation of the strip thickness from the average strip thickness.
This changes the speed of the input motor M1 in such a way that the instantaneous unevenness of the strip is compensated for in the draft zone.
Due to the absolute time independence of the strip mass control, its effect is only determined by the distance covered by the axis of the input motor M1, the time tR between measuring the actual value IW / EM at the measuring point MO and the output of the setpoint SW / D can always be different.
The writing of actual value measurement pairs IW / EM with the associated position of the reaction point SW / R and the output of setpoints SW / D are two different processes which are not necessarily linked to one another, but only use the same memory S. Writing new value pairs IW / EM / SW / R into the memory does not automatically result in the output of a setpoint SW / D.

• die Eingangsbandmasse EM
• die Dublierung D
• die Ausgabebandmasse AM
• die Istwertbandmasse des Probebandes IM/P

in den Speicher eingegeben.
Die Istwertbandmasse wird durch den Lauf eines in seiner Länge frei wählbaren Probebandes ermittelt und ist Voraussetzung, daß bei jedem beliebigen Faserband der Prozeß der Steuerung auf einem Grundverzug geeicht wird.To carry out the procedure, ET

• the input band mass EM
• the duplication D
• the output tape mass AM
• the actual tape mass of the sample tape IM / P

entered into memory.
The actual value sliver mass is determined by running a freely selectable length of the test sliver and is a prerequisite that the process of the control is calibrated to a basic delay for any sliver.

• Es ist kein Regelkreis mit einer der Verzugszone nachgeordneten Meßeinrichtung erforderlich.
• Es werden alle Ungleichmäßigkeiten im Band präzise bearbeitet, es bleiben keine Teilstücke zwischen Meßort und Kontrollort unbeeinflußt.
• Es ist keine Grenze für die Bemessung des Steuerbereiches im Plus- und Minusbereich gegeben.
• Die Lage des Reaktionspunktes ist nicht zwangsweise vorgegeben, diese kann den Verarbeitungsbedingungen angepaßt werden.
• Die Maschinengeschwindigkeit hat keinen Einfluß auf das Arbeitsregime, so daß Anfahr- und Abtourvorgänge der Maschine gleichermaßen exakt behandelt werden.
• Es ist keine externe Verzugsberechnung erforderlich, dies erfolgt intern im Prozessor. Am Terminal werden nur textiltechnisch relevante praktische Daten des Spinnplanes eingegeben.

Particular advantages of this procedure are:

• There is no need for a control loop with a measuring device downstream of the warpage zone.
• All irregularities in the strip are processed precisely, no sections between the measuring point and the control point remain unaffected.
• There is no limit for the measurement of the control range in the plus and minus range.
• The position of the reaction point is not mandatory, it can be adapted to the processing conditions.
• The machine speed has no influence on the working regime, so that starting and turning off of the machine are treated equally precisely.
• No external delay calculation is required, this is done internally in the processor. Only practical data of the spinning plan relevant to the textile technology are entered at the terminal.

Claims (6)

Process for the equalization of textile slivers in a drawing field in which the sliver feed and sliver discharge are driven separately, characterized in that the input sliver mass (EM) by means of an absolute encoder (4), independently of the sliver speed and the size of the measured value, in freely selectable steps (x) it is measured that each measured value (IW / EM) is assigned an absolute position as a reaction point (SW / R), these two values (IW / EM // SW / R) are stored together in a memory (S), the actual value ( IW / EM) is called up at a freely selectable point (R) in its position and is given to the motor (M1) via a frequency controller (fN) and serves as the speed setpoint (SW / D). Method according to 1, characterized in that an average is formed from a freely selectable number of measured values (IW / EM) and this value is stored in the memory as a measured value (IW / EM) with associated reaction point (SW / R). Method according to 1 or 2, characterized in that the processor (P) recognizes the actual value (IW / EM) when the assigned position at the reaction point (SW / R) is reached and outputs the setpoint (SW / D) to the motor. Method according to 3, characterized in that the setpoint value (SW / D) output to the motor (M1) corresponds to the speed currently required for the change in distortion associated with the strip unevenness. Method according to 1, 3 and 4, characterized in that the motor speed of the tape feed drive (M1) is always changed regardless of the absolute size of the measuring steps (x) when the measuring point reaches the reaction point (R). Method according to 2-4, characterized in that the motor speed of the tape feed drive (M1) is always changed regardless of the absolute size of the measuring steps (x) when the beginning of the respective measuring section reaches the reaction point (R).

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