EP1036869B1 - Verfahren und Vorrichtung zur Überwachung von Schussfaden in Webverfahren oder dergleichen - Google Patents

Verfahren und Vorrichtung zur Überwachung von Schussfaden in Webverfahren oder dergleichen Download PDF

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Publication number
EP1036869B1
EP1036869B1 EP20000104465 EP00104465A EP1036869B1 EP 1036869 B1 EP1036869 B1 EP 1036869B1 EP 20000104465 EP20000104465 EP 20000104465 EP 00104465 A EP00104465 A EP 00104465A EP 1036869 B1 EP1036869 B1 EP 1036869B1
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EP
European Patent Office
Prior art keywords
signal
yarn
rotation rate
feeder
weft
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Expired - Lifetime
Application number
EP20000104465
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English (en)
French (fr)
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EP1036869A1 (de
Inventor
Pietro Zenoni
Luca Gotti
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LGL Electronics SpA
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LGL Electronics SpA
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Publication date
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Publication of EP1036869A1 publication Critical patent/EP1036869A1/de
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    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D51/00—Driving, starting, or stopping arrangements; Automatic stop motions
    • D03D51/18—Automatic stop motions
    • D03D51/34—Weft stop motions

Definitions

  • the present invention relates to a method and a device for weft yarn monitoring in weaving processes.
  • weft feeders which are devices equipped with a fixed drum and with a windmilling arm which winds onto the drum a plurality of turns of yarn which constitute a weft reserve. The turns unwind in a controlled manner from the drum when required by the loom at each beat.
  • sensors which are adapted to detect the presence of the yarn at the input of the feeder. Their purpose is to indicate whether the weft yarn has broken, so that a monitoring system associated with the feeder can send halting information for the loom and halt said loom before the weft reserve of said feeder is used up completely by said loom; this circumstance can cause gaps in the fabric being woven and in any case forces one to rethread the entire feeder, with consequent prolonged suspensions of the weaving process.
  • piezoelectric sensors provided with a piezoelectric plate which acts as a sensitive element and is coupled to at least one ceramic element which acts as a yarn support.
  • the yarn slides on the ceramic element, generating a vibration which is transmitted to the piezoelectric plate, which in turn generates a substantially pulsed voltage which constitutes the yarn presence signal.
  • load cells are also used which are adapted to produce an electric signal which is proportional to the mechanical tension of the yarn.
  • the signal produced by the sensor is processed in a known manner in an amplifier and discriminator circuit, for example of the type shown in Figure 1 and described hereinafter, and is applied to a microprocessor in the form of a high or low digital signal which is present at the output of a final comparator of the circuit; the microprocessor is adapted to generate a loom halt signal if the weft presence signal provided by the sensor is missing.
  • This conventional weft yarn monitoring system has many drawbacks, the main one being the extreme sensitivity of the system to various factors, hereinafter concisely termed weaving factors, such as in particular the roughness and count of the yarn, the speed with which the yarn slides on the presence sensor of the feeder and/or the mechanical tension with which it adheres to it.
  • the relation between the signal emitted by the sensor, whether piezoelectric or load-sensing, and the weaving factors is an increasing relation, in that the higher the roughness and/or travel speed and/or contact tension of the yarn, the higher the intensity of the signal emitted by the sensor.
  • the amplification of the presence sensor signal cannot be excessively high and the comparison threshold cannot be excessively low, since this would cause, in the presence of high-value weaving parameters and therefore of a correspondingly high presence signal, an undesirable amplification of the noise associated with the high signal, for example resonance noise which, by exceeding the comparison threshold, would in turn cause the system to fail to intervene.
  • the aim of the present invention starting from the notion of the drawbacks of conventional monitoring methods and systems, is to eliminate them, and within the scope of this aim the invention has the important particular object of providing a monitoring method and device which ensure prompt and assured intervention of the loom halting system even in the presence of highly unfavorable weaving factors, particularly low yarn travel speeds and in the presence of low-count yams with high surface continuity (for example glossy yarns).
  • Another important object of the present invention is to provide a monitoring device which is simple and reliable and is entirely constituted by solid-state electronic components and has absolutely no mechanical elements that interact with the monitored weft yarn.
  • the invention is based on the concept of monitoring the weft yarn by means of a system which has means for amplifying the signal produced by a weft presence sensor and means for comparing the amplified signal of the sensor with a parametric reference voltage and to correspondingly vary, in said system, the amplification gain and/or the parametric reference voltage as the value of one or more weaving factors varies correspondingly.
  • a monitoring system with an amplifier and a comparator for processing the weft presence sensor signal, in which a signal which is proportional to the rotation rate of the windmilling arm of the feeder is sent to the microprocessor that controls the entire weaving process and provides, on a dedicated output, a system adjustment signal which is inversely proportional to said rotation rate; said adjustment signal being adapted to vary the gain of said amplifier, decreasing as said rotation rate increases and increasing it as said speed decreases.
  • the microprocessor is programmed in order to generate an adjustment datum, in terms of parametric comparison voltage, which is directly proportional to said rotation rate, so as to increase the parametric reference voltage applied to the comparator means as said rotation rate increases and so as to decrease the voltage as the rate decreases.
  • the reference sign T generically designates a weaving loom, for example of the high-speed type; the reference numeral 10 designates a conventional system for feeding the weft yarn F to the loom T; and the reference numeral 20 designates the equally known system for monitoring the weft yarn F.
  • the system 10 substantially comprises a weft feeder 11 with a fixed drum 12 on which a windmilling arm, associated with a rotating disk 13 arranged at the base of the drum, winds a plurality of turns of yarn F, which unwinds from a spool 14; said turns constitute a weft reserve RT.
  • a sensor 15 which is meant to report any yarn breakage to the monitoring system 20, so that the system 20 promptly halts the loom T before said loom uses up entirely the weft reserve RT.
  • the system 20 comprises an amplifier 21, to which the signal s1 from the sensor 15 is applied; the amplifier is followed by a bandpass filter 22, whose output signal s3 is first rectified by a diode D and then filtered by a low-pass filter 23 constituted by a unit R1-C1 with which a resistor R2 for discharging the capacitor C1 is associated.
  • the rectified and filtered output signal s4 is applied to the positive input of a comparator 24 which compares signal s4 with a DC reference voltage VR, providing on its output U a high (digital) signal st when s4 is higher than VR (presence of weft yarn F) and, vice versa, a low signal (lack of weft yarn F) when s4 is smaller than VR.
  • a microprocessor ⁇ P which receives the signal st on a dedicated input, emits on one of its outputs a halting signal AR for the loom T.
  • the above-described monitoring system is improved as shown in Figure 2, in which similar or corresponding components are designated by the same reference numeral and which shows that said improved system, generally designated by the reference numeral 20', comprises an input amplifier 21' of the variable-gain type, driven by the signal that is present at the output of a digital/analog converter 25 which receives in input a datum supplied by the microprocessor ⁇ P.
  • the microprocessor receives, on one of its inputs, a signal sa which originates from the feeder 11 and is proportional to the rotation rate W of the windmilling arm of the feeder and is programmed so that the signal that controls the gain G of the amplifier 21' varies substantially in inverse proportion to the signal sa related to the rotation rate W. Accordingly, the gain G of the amplifier 20' (and, correspondingly, the signal s4 applied to the comparator 24) vary as shown in the chart of Figure 2a, decreasing as the rotation rate W increases and increasing as said rate decreases.
  • the microprocessor ⁇ P of the monitoring system 20" is programmed so as to generate a datum VR which can vary in direct proportion to the signal sa that corresponds to the rotation rate W and is applied to a converter 25".
  • a datum VR expressed in voltage terms, which is adapted to be applied to the comparator 24, in order to supply a parametric comparison voltage which, as clearly shown in Figure 3a, is directly proportional to the rotation rate W of the feeder 11, i.e., it increases and decreases as said rotation rate increases and decreases.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Looms (AREA)
  • Spinning Or Twisting Of Yarns (AREA)
  • Treatment Of Fiber Materials (AREA)

Claims (10)

  1. Verfahren zur Überwachung von Schussfaden in Webprozessen, bei dem der Schussfaden (F) der Webmaschine (T) mittels einer Zuführvorrichtung (11) mit einem Windmühlenarm zum Abgeben einer Vielzahl von Windungen Faden (F), die eine Schussfadenreserve (RT) bilden, zugeführt wird, wobei das Verfahren die folgenden Schritte umfasst: Erzeugen eines Signals (s1), das das Vorhandensein des Fadens am Eingang der Zuführvorrichtung (11) anzeigt, Verstärken und Gleichrichten des Signals, und Vergleichen des Signals mit einer parametrischen Referenzspannung (VR), um ein Signal zum Anhalten der Webmaschine bei fehlendem Faden-Vorhanden-Signal (s1) zu erhalten, dadurch gekennzeichnet, dass es die zusätzlichen Schritte umfasst, die Verstärkung (G) des Vorhanden-Signals (s1) und/oder die parametrische Referenzspannung (VR) entsprechend zu verändern, wenn sich einer oder mehrere Faktoren des Webprozesses entsprechend verändern.
  2. Überwachungsverfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Faktoren des Webprozesses Fadenfeinheit und -art, Bewegungsgeschwindigkeit und mechanische Spannung umfassen.
  3. Überwachungsverfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Verstärkung (G) und/oder die parametrische Referenzspannung (VR) im Verhältnis zu der Veränderung der Fadenbewegungsgeschwindigkeit verändert werden, die durch Nachweis der Drehgeschwindigkeit (W) des Windmühlenarms der Schussfaden-Zuführvorrichtung (11) gemessen wird.
  4. Überwachungsverfahren nach Anspruch 3, dadurch gekennzeichnet, dass es den Schritt umfasst, ein Signal (sa) zu erzeugen, das proportional zu der Drehgeschwindigkeit (W) des Windmühlenarms der Zuführvorrichtung (11) ist, und das Signal (sa) an einen Mikroprozessor (µP) zu senden, der programmiert ist, an einem seiner Ausgänge ein veränderliches Einstellsignal (g') zu liefern, das dafür eingerichtet ist, die Verstärkung (G) des Faden-Vorhanden-Signals (s1) umgekehrt proportional zu der Drehgeschwindigkeit (W) zu verändern, die Verstärkung (G) zu verkleinern, wenn die Drehgeschwindigkeit (W) größer wird, und sie zu vergrößern, wenn die Geschwindigkeit kleiner wird, um die Erzeugung von falschen Anhaltesignalen (AR) für die Webmaschine (T) zu vermeiden.
  5. Überwachungsverfahren nach Anspruch 3, dadurch gekennzeichnet, dass es den Schritt umfasst, ein Signal (sa) zu erzeugen, das proportional zu der Drehgeschwindigkeit (W) des Windmühlenarms der Zuführvorrichtung (11) ist, und das Signal (sa) an einen Mikroprozes-sor (µP) zu senden, der programmiert ist, einen Einstellwert (VR") in Form einer parametrischen Referenzspannung zu erzeugen, der direkt proportional zu der Drehgeschwindigkeit (W) ist, um die parametrische Referenzspannung (VR), mit der das verstärkte und gleichgerichtete Faden-Vorhanden-Signal (s4) verglichen wird, zu vergrößern, wenn die Drehgeschwindigkeit (W) größer wird, und die parametrische Spannung (VR) zu verkleinern, wenn die Drehgeschwindigkeit kleiner wird, um die Erzeugung von falschen Anhaltesignalen (AR) für die Webmaschine (T) zu vermeiden.
  6. Vorrichtung zur Überwachung von Schussfaden (F) zur Durchführung des Überwachungsverfahrens nach Anspruch 1, mit Verstärkermitteln (21') für ein Schussfaden-Vorhanden-Signal (s1), das von einem Sensor (15) erzeugt wird, der am Eingang einer Schussfaden-Zuführvorrichtung (11) mit einem Windmühlenarm angeordnet ist, der eine Schussfadenreserve (RT) auf die Trommel der Zuführvorrichtung (11) wickelt, und Vergieichermitteln, die ein Signal (AR) zum Anhalten der Webmaschine (T) erzeugen und dafür eingerichtet sind, das Vorhanden-Signal (s1) mit einer parametrischen Referenzspannung (VR) zu vergleichen, dadurch gekennzeichnet, dass sie Mittel (21'-µP), die für die Drehgeschwindigkeit (W) des Windmühlenarms empfindlich sind, um die Verstärkung (G) der Verstärkermittel (21') umgekehrt proportional zu der Drehgeschwindigkeit (W) zu verändern, und/oder Mittel (µP) zum Verändern der den Vergleichermitteln (24) zugeführten parametrischen Referenzspannung (VR) direkt proportional zu der Drehgeschwindigkeit (W) aufweist.
  7. Vorrichtung zur Überwachung von Schussfaden (F), nach Anspruch 6, dadurch gekennzeichnet, dass die Verstärkermittel einen Verstärker (21') mit veränderlicher Verstärkung aufweisen und dass die Verstärkung (G) des Verstärkers durch ein entsprechend veränderliches Signal (g'), das von einem Mikroprozessor (µP) erzeugt wird, der am Eingang ein Signal (sa) empfängt, das proportional zu der Drehgeschwindigkeit (W) ist, dazu gebracht wird, sich umgekehrt proportional zu der Drehgeschwindigkeit (W) der Zuführvorrichtung (11) zu verändern.
  8. Vorrichtung zur Überwachung von Schussfaden (F) zur Durchführung des Verfahrens nach Anspruch 6, dadurch gekennzeichnet, dass sie einen Mikroprozessor (µP) aufweist, der am Eingang ein Signal (sa) empfängt, das proportional zu der Drehgeschwindigkeit (W) des Windmühlenarms ist, und programmiert ist, einen veränderlichen Einstellwert (VR") in Form einer parametrischen Referenzspannung zu erzeugen, die den Vergleichermitteln (24) zugeführt wird; der Referenzwert (VR") ist direkt proportional zu der Drehgeschwindigkeit (W) des Windmühlenarms veränderlich.
  9. Vorrichtung nach Ansprüchen 6, 7 oder 8, dadurch gekennzeichnet, dass der Sensor (15), der das Signal (s1) erzeugt, das das Vorhandensein des Fadens (F) anzeigt, vom piezoelektrischen Typ ist.
  10. Vorrichtung nach Ansprüchen 6, 7 oder 8, dadurch gekennzeichnet, dass der Sensor (15), der das Signal (sa) erzeugt, das das Vorhandensein des Fadens (F) anzeigt, durch eine Kraftmessdose gebildet wird.
EP20000104465 1999-03-16 2000-03-08 Verfahren und Vorrichtung zur Überwachung von Schussfaden in Webverfahren oder dergleichen Expired - Lifetime EP1036869B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO990204 1999-03-16
IT1999TO000204 IT1308812B1 (it) 1999-03-16 1999-03-16 Metodo e dispositivo perfezionati di monitoraggio del filato di tramanei processi di tessitura e simili.

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EP1036869A1 EP1036869A1 (de) 2000-09-20
EP1036869B1 true EP1036869B1 (de) 2004-02-25

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DE (1) DE60008443T2 (de)
IT (1) IT1308812B1 (de)

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JP4128458B2 (ja) * 2003-01-22 2008-07-30 津田駒工業株式会社 織機における緯糸検知方法
EP2075209A1 (de) * 2007-12-28 2009-07-01 L.G.L. Electronics S.p.A. Vorrichtung zum Messen der Fadenspannung

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IT1224443B (it) * 1987-12-31 1990-10-04 Roy Electrotex Spa Tastatrama a regolazione automatica del tempo di ritardo per porgitrama di telai senza navetta
BE1005824A3 (nl) * 1992-05-22 1994-02-08 Picanol Nv Werkwijze voor het bepalen van een spanning in een inslagdraad.

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DE60008443T2 (de) 2005-01-13
DE60008443D1 (de) 2004-04-01
IT1308812B1 (it) 2002-01-11
EP1036869A1 (de) 2000-09-20
ITTO990204A1 (it) 2000-09-16

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