EP3587639A1 - Optical device for the detection of short wefts in a weaving machine - Google Patents

Optical device for the detection of short wefts in a weaving machine Download PDF

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Publication number
EP3587639A1
EP3587639A1 EP19182502.5A EP19182502A EP3587639A1 EP 3587639 A1 EP3587639 A1 EP 3587639A1 EP 19182502 A EP19182502 A EP 19182502A EP 3587639 A1 EP3587639 A1 EP 3587639A1
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EP
European Patent Office
Prior art keywords
optical
weft thread
signal
weaving machine
optical device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19182502.5A
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German (de)
English (en)
French (fr)
Inventor
Andrea LUZZANA
Fabio NODARI
Jan WRUCK
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Itema SpA
Original Assignee
Itema SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Itema SpA filed Critical Itema SpA
Publication of EP3587639A1 publication Critical patent/EP3587639A1/en
Withdrawn legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D03D47/28—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed
    • D03D47/30—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed by gas jet
    • D03D47/3066—Control or handling of the weft at or after arrival
    • D03D47/3073—Detection means therefor
    • 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
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D03D47/28—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed
    • D03D47/30—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed by gas jet

Definitions

  • the present invention relates to an optical device for the detection of short wefts in shuttleless weaving machines, such as projectile looms, air looms and gripper looms.
  • short wefts refers to those wefts which - due to the intrinsic elasticity of the thread or to a dynamic effect in the weft insertion - try to go back into the shed, even only partially, after their insertion is completed, so producing an uneven fringe of weft tails or marking the fabric with a clear defect.
  • the optical device for the detection of short wefts finds an effective application whenever is necessary to verify the actual presence of a weft thread in the different weft thread retention means (fixed or movable grippers, false selvedge, or extender nozzle) which are possibly used in the various types of weaving machine listed above, in order to keep the weft thread fully outstretched over the period of time which runs from the time the weft thread is completely inserted into the shed to the beating up of the same by the reed against the fabric being formed.
  • weft thread retention means fixed or movable grippers, false selvedge, or extender nozzle
  • a particularly complete and effective application of the optical device for the detection of short wefts according to the invention is in conjunction with a weaving method wherein, upon the insertion of a weft thread into the shed, the retaining means of said weft thread consist of two grippers, arranged at the opposite ends of the shed, which move together with the weft thread towards the reed beating up line, and therefore in the same direction as the reed and slightly forward thereof.
  • step 1 the projectile P goes through the shed, accomplishing the insertion of weft thread T, and then is halted within the brake and hence moved back into the coupling position of the projectile return system, which system returns the projectile to the side of the loom from which the insertion of weft thread T takes place (left side in the diagram of Fig. 1 ).
  • step 2 while the weft thread T is still kept under tension between the weft-tensioning device and the projectile P in the direction indicated by the arrows, two selvedge grippers Gs and Gd, which are arranged on the left side and right side of the loom respectively, are advanced towards the weft thread T to hook and block the weft thread T.
  • the projectile P gripper is opened, thus releasing the free end of the just inserted weft thread T and allowing the return movement of projectile P from the right side to the left side of the loom to take place.
  • step 3 selvedge grippers Gs and Gd move simultaneously towards the beating up position, together with the clamped weft thread T into the direction indicated by the arrows, while at the same time shed closure is started by a weave machine (dobby) and a reed R advances towards the beating up position.
  • step 4 the weft thread T is finally beaten up by the reed R and incorporated into the fabric C being formed.
  • the weft thread insertion cycle can therefore start again, soon after the weft thread T is cut at the left side of the loom, and the selvedge grippers Gs and Gd are opened in view of their successive advancement (at the beginning of step 2) towards the insertion position of a new weft thread T.
  • a selvedge grippers malfunction may occur in two main modes:
  • the problem underlying the present invention is therefore to provide a weft thread detection device which makes it possible to verify on projectile looms the actual presence of the last inserted weft thread, at the left and right ends of the shed, during the period of time between the insertion of a weft thread and the beating up of the same by the reed, i.e. during the period where the selvedge grippers are active, so that, if the absence of a weft thread is detected, the operation of the loom can be halted and a weft removal cycle of the wrong weft can be started.
  • a first object of the present invention is therefore to provide an optical device for the detection of a weft thread having extremely small bulk in the loom transverse direction, i.e. the direction of insertion of the weft threads.
  • Another object of the present invention is to provide an optical device for the detection of a weft thread which is not very liable to be impaired by weaving waste and therefore is able to uninterruptedly operate for a sufficiently long period of time before requiring cleaning interventions.
  • a further object of the present invention is then to provide an optical device for the detection of a weft thread provided with an alarm system apt to promptly alert when critical conditions of the optical signal have been attained, due to accumulated weaving waste, and then a cleaning operation of the optical device is needed.
  • Yet another object of the invention is finally to provide an optical device for the detection of a weft thread which is indifferent to any change in actual lighting conditions.
  • an optical device for the detection of weft threads consisting of three distinct elements, namely a base optical unit, an optical fibre sensor, and a processing unit of the detected signal.
  • the base optical unit includes an optical transmitter and an optical receiver and provides for the generation and reception of the optical signal, for its transformation into an appropriately filtered electric signal i.e. the detected signal, and for its analog transmission.
  • the optical fibre sensor provides for the transfer of the optical signal from the base optical unit to the weft thread detection position, and vice versa, and consists of a plate with two prongs, each one provided with an optical fibre housed in a respective seat, said optical fibres being convergent at one end towards the weft thread detection position, and being respectively connected, at the opposite end, to said optical transmitter and optical receiver.
  • the processing unit of the analog signal coming from the optical receiver consists of a digital signal processor (DSP), which carries out the analog-to-digital conversion of the analog signal coming from the optical receiver, and then logically interprets the converted digital signal in order to verify the presence/absence of the weft thread, and furthermore communicates with the weaving machine control system.
  • DSP digital signal processor
  • the optical fibre sensor can be thus easily and efficiently arranged in the narrow area where the weft thread passage needs to be monitored, by using the optical signals coming from the nearby base optical unit (not shown in the drawings) - housed in a less critical position in terms of bulkiness - which optical signals are then transferred back again to the base optical unit for their conversion into electric signals and for the subsequent digital conversion and signal analysis through the processing unit of the detected signal.
  • FIG. 2 it can be clearly seen as this optical fibre sensor simply consists of a two prongs-plate 2, having a small thickness in the direction of weft insertion, wherein optical fibres 3 and 4 are steadily housed.
  • Plate 1 is arranged laterally to the warp threads W and to the fabric being formed, in the gap between these last and the selvedge grippers Gs and Gd on the two sides of the loom, respectively.
  • Fig. 4 which illustrates the plate 1 side opposite to that shown in Figs. 2 and 3 , it can be seen that this plate includes an upper prong It and a lower prong 1b, divided by a cavity 2, and that the free ends 1e of said prongs are mutually faced one another at a sufficient distance to allow the passage of weft threads T into the cavity 2. Longitudinal grooves are further formed in the thickness of said prongs 1t and 1b, which provide housing seats for respective optical fibres 3 and 4.
  • Said longitudinal grooves extend from the free ends 1e of the prongs 1t and 1b up to the opposite end of plate 1 and are formed so as to be perfectly aligned at the prongs free ends and, moreover, to comply in their curvilinear portions with the minimum admissible curvature radius which does not compromise the integrity of optical fibres 3 and 4 housed therein. Correct positioning of optical fibres 3 and 4 on plate 1 and, particularly, their optical alignment at the free ends 1e is thus extremely simple, making it possible to form a detection light beam L which goes with high efficiency from optical fibre 3, connected to the optical transmitter of the base optical unit, to optical fibre 4, connected to the optical receiver of the same base optical unit.
  • plate 1 is preferably formed of a suitable metal material and is fixed, for example through screws housed in holes 6, to a support base 5 integral with the loom.
  • Shape of the cavity 2 provided inside plate 1 is not particularly limited, being only necessary that it is long and wide enough to prevent any possible contact between said prongs 1t and 1b and the weft threads T which slide inside the cavity 2 - carried by selvedge grippers Gd, Gs and by reed R - along the line F between the weft thread insertion position Ti and the weft thread beating up position Tb where the weft thread is beaten up against the fabric C being formed.
  • the optical device for the detection of weft threads of the present invention verifies, in fact, the presence of weft thread T during the return movement of selvedge grippers Gs, Gd from the insertion position Ti of the weft thread - in which position the weft thread has been gripped by said selvedge grippers Gs, Gd - towards the weft thread beating up position Tb, against the fabric C being formed, and hence immediately before the closure of the shed.
  • Any weft thread which is possibly lost by the selvedge grippers after the closure of the shed is not relevant, as in any case such lost weft thread does not lead to defects in the fabric.
  • the optical device for the detection of weft threads carries out a barrier type optical control: the light beam produced by the optical transmitter of the base optical unit is transported in fact along the optical fibre 3 up to the free end of prong It and here is transferred to the optical fibre 4 housed in prong 1b, forming the light beam L for the detection of weft threads through the free space between the opposing free ends of the two prongs 1t and 1b.
  • the optical signal is then carried by optical fibre 4 to the optical receiver housed in the base optical unit, which transforms the same into an electric signal.
  • Said analogic electric signal is subsequently converted into a digital signal and monitored through a digital signal processor (DSP) provided within the processing unit of the detected signal.
  • DSP digital signal processor
  • the DSP is programmed according to a suitable algorithm which makes it possible to recognize the presence or absence of such modified electric signal and, consequently, to verify the actual passage of a weft thread. When the presence of such modified electric signal is not detected, the DSP will send a warning signal to the weaving machine control system in order to cause its halting and thus allow usual manual or automatic interventions for repairing the short weft.
  • the electronic infrastructure of the optical device for the detection of short wefts according to the present invention consists of two distinct portions: an analog front-end which controls the optical transmitter and the optical receiver, and a digital back-end which provides analog-to-digital conversion of the signal, processing of the digitalised signal, and any communication with the weaving machine control system.
  • the optical device for the detection of short wefts according to the invention includes two electronic cards containing the analog front-ends, arranged at the two sides of the weaving machine, and a main electronic card containing the pair of digital back-ends and their related wirings.
  • the analog front-end oversees the following functions:
  • the digital back-end oversees the functions of:
  • the algorithm that makes it possible to verify the presence of a weft thread, through the analysis of the digital signal in the DSP, includes three different subsequent operation steps, closely related to three different periods of each individual cycle of weft thread insertion in the weaving machine:
  • the algorithm In the alignment and detection steps, usual data filtering techniques are applied, in order to make the algorithm less sensitive to any noise, as optical or electromagnetic noises. In each of the previous operation steps, the algorithm also monitors the quality of the signal in terms of amplitude and noise, generating alert messages towards the weaving machine control system, if necessary.
  • control algorithm of the optical device for the detection of short wefts accomplishes other control and supervision tasks carried out following a rigidly predefined time schedule.
  • the main tasks among these are the following:
  • the optical device for the detection of short wefts of the present invention fully achieved the intended objects.
  • the optical sensor thanks to the use of an optical fibre sensor which is separated from the optical unit for transmitting and receiving the optical signal, it is possible for the optical sensor to have a flat and thin shape, which shape allows the easy insertion of the optical sensor into the narrow areas where the presence of a weft thread must be detected.
  • the same thin plate shape of the optical fibre sensor makes such a sensor less inclined to the accumulation of textile waste and therefore able to offer satisfactory performance for sufficiently long uninterrupted periods of time between two subsequent cleaning interventions.
  • the optical device of the invention is completely insensitive to the specific ambient light conditions and to their variations, so maintaining a constant sensitivity in detection of weft threads.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Looms (AREA)
  • Treatment Of Fiber Materials (AREA)
EP19182502.5A 2018-06-29 2019-06-26 Optical device for the detection of short wefts in a weaving machine Withdrawn EP3587639A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT102018000006835A IT201800006835A1 (it) 2018-06-29 2018-06-29 Dispositivo ottico per il rilevamento delle trame corte in un telaio tessile

Publications (1)

Publication Number Publication Date
EP3587639A1 true EP3587639A1 (en) 2020-01-01

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EP19182502.5A Withdrawn EP3587639A1 (en) 2018-06-29 2019-06-26 Optical device for the detection of short wefts in a weaving machine

Country Status (4)

Country Link
EP (1) EP3587639A1 (ja)
JP (2) JP2020002519A (ja)
CN (1) CN110656427A (ja)
IT (1) IT201800006835A1 (ja)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3907440A (en) * 1972-10-16 1975-09-23 Loepfe Ag Geb Optoelectrical apparatus
JPS60199950A (ja) * 1984-03-23 1985-10-09 日産自動車株式会社 空気噴射式織機の緯入れ制御装置
US5063973A (en) * 1989-03-08 1991-11-12 Kabushiki Kaisha Ishikawa Seisakusho, Ltd. Reed dent with optical weft detecting device
JPH0598543A (ja) * 1991-10-07 1993-04-20 Toyota Autom Loom Works Ltd ジエツトルームにおける緯糸検出装置
JPH07279012A (ja) * 1994-04-07 1995-10-24 Tsudakoma Corp 織機の緯糸検知装置
WO1999030108A1 (en) * 1997-12-11 1999-06-17 Scientific Technologies Incorporated Optically based on-line fiber monitoring system with drift compensation

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0204093B1 (en) * 1985-04-05 1989-08-02 Kabushiki Kaisha Toyoda Jidoshokki Seisakusho A method and an apparatus for detecting the weft yarn in a jet loom
JP3447919B2 (ja) * 1997-06-11 2003-09-16 津田駒工業株式会社 透過式緯糸検出装置
CN1108406C (zh) * 1999-03-22 2003-05-14 Iropa股份公司 用于对纬纱插入织机中的操作循环进行监控的方法
DE102009035904A1 (de) * 2009-08-03 2011-02-10 Lindauer Dornier Gmbh Verfahren und Vorrichtung zur Überwachung der Fadenankunft beim Schusseintrag verschiedener Schussfäden an einer Webmaschine
JP5530686B2 (ja) * 2009-09-16 2014-06-25 津田駒工業株式会社 水噴射式織機用の緯糸検知装置
CN205188559U (zh) * 2015-11-25 2016-04-27 南通鲁润纺织机械有限公司 一种喷气织机的管道式光电探纬结构

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3907440A (en) * 1972-10-16 1975-09-23 Loepfe Ag Geb Optoelectrical apparatus
JPS60199950A (ja) * 1984-03-23 1985-10-09 日産自動車株式会社 空気噴射式織機の緯入れ制御装置
US5063973A (en) * 1989-03-08 1991-11-12 Kabushiki Kaisha Ishikawa Seisakusho, Ltd. Reed dent with optical weft detecting device
JPH0598543A (ja) * 1991-10-07 1993-04-20 Toyota Autom Loom Works Ltd ジエツトルームにおける緯糸検出装置
JPH07279012A (ja) * 1994-04-07 1995-10-24 Tsudakoma Corp 織機の緯糸検知装置
WO1999030108A1 (en) * 1997-12-11 1999-06-17 Scientific Technologies Incorporated Optically based on-line fiber monitoring system with drift compensation

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IT201800006835A1 (it) 2019-12-29
JP3238799U (ja) 2022-08-22
JP2020002519A (ja) 2020-01-09
CN110656427A (zh) 2020-01-07

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