EP0826806B1 - Weft brake particularly for air-jet looms - Google Patents

Weft brake particularly for air-jet looms Download PDF

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Publication number
EP0826806B1
EP0826806B1 EP19970114831 EP97114831A EP0826806B1 EP 0826806 B1 EP0826806 B1 EP 0826806B1 EP 19970114831 EP19970114831 EP 19970114831 EP 97114831 A EP97114831 A EP 97114831A EP 0826806 B1 EP0826806 B1 EP 0826806B1
Authority
EP
European Patent Office
Prior art keywords
thread
weft brake
brake according
deviation means
weft
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.)
Expired - Lifetime
Application number
EP19970114831
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0826806A1 (en
Inventor
Pietro Zenoni
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.)
LGL Electronics SpA
Original Assignee
LGL Electronics 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 LGL Electronics SpA filed Critical LGL Electronics SpA
Publication of EP0826806A1 publication Critical patent/EP0826806A1/en
Application granted granted Critical
Publication of EP0826806B1 publication Critical patent/EP0826806B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • D03D47/34—Handling the weft between bulk storage and weft-inserting means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H59/00—Adjusting or controlling tension in filamentary material, e.g. for preventing snarling; Applications of tension indicators
    • B65H59/10—Adjusting or controlling tension in filamentary material, e.g. for preventing snarling; Applications of tension indicators by devices acting on running material and not associated with supply or take-up devices
    • B65H59/20—Co-operating surfaces mounted for relative movement
    • B65H59/26—Co-operating surfaces mounted for relative movement and arranged to deflect material from straight path
    • B65H59/32—Co-operating surfaces mounted for relative movement and arranged to deflect material from straight path the surfaces being urged away from each other
    • B65H59/34—Surfaces movable automatically to compensate for variation in tension
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2701/00—Handled material; Storage means
    • B65H2701/30—Handled filamentary material
    • B65H2701/31—Textiles threads or artificial strands of filaments

Definitions

  • the present invention relates to an improved weft brake particularly for air-jet looms, which can be inserted between a weft feeder and a main pneumatic air-jet insertion device arranged on the beater of the reed of the loom.
  • Weft braking devices are typically used in air-jet looms to reduce the speed of the weft thread shortly before its insertion between the warp threads is completed at each beat of the loom. Since in modern looms and particularly in air-jet looms each individual insertion lasts only a few milliseconds, it is necessary to slow the thread before stopping it to prevent the occurrence of peaks of mechanical tension which can easily break said thread.
  • the weft length required for each insertion is in fact usually measured by the feeder in the form of a preset number of turns which unwind from the fixed drum of the feeder.
  • An optical reader is provided in order to count the unwinding turns and when the preset number of unwound turns is reached a stop element is activated in order to stop the unwinding of said turns.
  • the stop element comprises a stop finger which moves radially with respect to the drum of the feeder under the actuation of an electromagnetic means and is suddenly lowered towards and against the drum to interfere with the unwinding of the thread and stop it.
  • This sudden stopping of the thread causes the onset of said peaks in mechanical tension, which easily break the thread; the smaller the count of the thread, the more frequent the breakages.
  • the weft brake which is interposed between the feeder and the pneumatic insertion device, has the purpose of slowing the weft thread before stopping it, since the tension peaks caused by stopping increase with the thread advancement speed; for this purpose, it is based on the concept of diverting the thread with respect to the straight path that it performs during insertion.
  • thread diversion is achieved by means of an element which moves in a linear fashion with fixed thread guides and interposed moving thread guides which are pushed against the thread to divert it during braking. Thread diversion can be partially eliminated after the tension peak has ceased, and there is provided an elastic damping means in order to yield, with a delayed reaction, to the force applied to the thread owing to the diversion.
  • the thread passes in a straight line through a plurality of fixed thread guides along its insertion path and is diverted, in order to slow it, by two diverting thread guides supported by a rotating support controlled by an electromagnetic actuator which, by moving the support in an angular fashion, pushes the diverting thread guides against the thread.
  • a transmission means is interposed between the diverting thread guide and the actuator and allows relative movement between the actuator and the thread guide in order to limit the increase in thread tension caused by braking and also keep the tension at a preset value.
  • All these conventional weft brakes have the drawback that they produce a limited and non-adjustable diversion of the thread. Accordingly, the speed reduction determined by the diversion angle applied to the thread can be unsuitable for the type of thread being processed. Moreover, the brakes do not allow, or allow only to a limited extent, to take up the thread and retension it as required by the subsequent weaving steps after speed reduction and after damping of the stopping tension peak.
  • EP-0 239 055 discloses a weft brake for air-jet looms with deviation means for the thread, as claimed in the preamble of claim 1.
  • the aim of the present invention is to eliminate these and other drawbacks, and within the scope of this general aim the invention has the important object of providing an improved weft brake with a thread diverter which has a linear motion and in which the breadth and speed of the movement of the diverter can both be adjusted within wide limits and the movement speed can also change, during brake intervention, according to a preset rule of motion.
  • Another particular object of the present invention is to provide a weft brake with a diverter which has a linear movement and is suitable to assume distinct positions for braking and taking up and retensioning the thread, which correspond to two end positions of the stroke of the diverter, so that transition from one position to the other is very quick and does not require reversal of the motion of the diverter.
  • Another particular object of the invention is to provide a weft brake with a thread diverter having a linear movement, wherein the transition of the diverter from the braking position to the non-braking or neutral position and to the takeup and retensioning positions or viceversa occur successively owing to a positive actuation which eliminates the use of elastic auxiliary means and allows to graduate both the extent and the speed and/or acceleration of the diverter, adapting the intervention of the brake to the requirements of the process and to the count of the thread being processed.
  • Another important object of the invention is to provide a weft brake which has a very simple and compact structure, has limited overall dimensions and is highly reliable in operation.
  • a weft brake with a thread diverter which has a linear movement and travels between two fixed and mutually aligned thread guiding bushes and in which said diverter is actuated by a reversible electric motor with the interposition of a bidirectional transmission, constituted by a screw which is associated with the driving shaft and cooperates with a female thread associated with the diverter (or viceversa).
  • the actuation motor is preferably of the brushless type and can be supplied with a modulated current which is suitable to produce preset rules of motion for said diverter.
  • the diverter comprises mutually opposite active surfaces which are suitable to engage the thread in order to divert it for corresponding mutually opposite operating positions of said diverter with respect to a neutral central position of said diverter.
  • Figure 1 shows a weft brake 10 inserted in a system for feeding weft thread FT to a loom 11, which comprises a bobbin of thread 12, a weft feeder 13 and a main weft insertion device 14.
  • the insertion device 14 is constituted by a pneumatic nozzle which is arranged on the slay 15 of the reed of the loom in order to insert, with the aid of auxiliary pneumatic inserters 16, the weft thread FT between the warp threads FO.
  • the length of the weft to be inserted at each beat is measured in a conventional manner by the feeder 13, on which a hollow arm 16 winds, in a windmilling fashion, a plurality of turns of thread which constitute a weft reserve.
  • the weft length is measured in the form of a preset number of turns which unwind from the drum of the feeder 13 when requested by the loom 11.
  • the unwinding turns are counted by an optical device (not shown), and when the preset number is reached, a stop element 17, by moving into an engagement position towards and against the drum, blocks the unwinding of the thread FT.
  • the weft brake 10 comprises a diverter 20 which moves in a straight line between two fixed thread guiding bushes 21 and 22 which are mutually aligned and form the straight path of the thread.
  • the thread guiding bushes 21 and 22 are supported at the corresponding ends of a fixed U-shaped fork 23 which is in turn arranged at the end of a supporting plate 24.
  • the end 25 of the plate which is opposite to the fork 23 is folded at right angles so as to act as a support for a reversible electric motor 26, which is supplied with a current i delivered by a power source G.
  • the motor 26 is of the brushless or equivalent type, such as a step motor and the like.
  • the diverter 20 is constituted by a slider 27 made of a rigid material, possibly a nonmetallic material, which moves along straight paths which are at right angles to the path of the thread FT and moves on the supporting plate 24 in sliding contact with the plate by means of a flat face 27a.
  • a blind cylindrical seat 28 which is internally threaded in order to constitute a female thread element.
  • An actuation screw cooperates by thread engagement with the female thread and is constituted by the correspondingly threaded portion 29a of the shaft 29 of the motor 26; the shaft protrudes outside the end of the support 25 and lies parallel to the plate 24 over a suitably long extent which is substantially equal to the depth of the seat 28.
  • the slider 27 has a front part 27a, which lies and moves between the fixed thread guiding bushes 21 and 22 and whereon there are provided mutually opposite active surfaces 30a and 30b which are suitable to engage the thread FT and divert it, so as to slow it, with respect to the straight path defined by the thread guiding bushes 21 and 22.
  • the active surfaces substantially have the profile of a circular segment and are supported by corresponding pawls 31a and 31b which are mutually opposite but are spaced so as to delimit a channel 32 for the free passage of the thread when the thread moves along the straight path and the diverter 20 is inactive.
  • Figures 5 to 7 show that the diverter, under the actuation of the motor 26, passes from the inactive or neutral position, which is designated by the reference numeral 20 in figure 5 and in which the thread FT passes freely in the channel 32, to the active position 20x for slowing the thread, shown for example in figure 6, in which the active surface 30a of the pawl 31a is pushed against the thread FT to divert it and slow it with a braking action which is proportional to the diversion angle [ ⁇ ], which in turn depends on the number of turns made by the driving shaft 29 in the braking interval and on the pitch of the thread of the screw 29a.
  • Screw pitch being equal, the rotation rate of the motor 26 and therefore the number of turns performed by the motor in the braking interval can be varied in order to adjust the brake 10 by acting on the power supply current i, for example by means of an electronic control CE which is associated with a power source G.
  • the same control CE can also be preset to modulate the current i so as to obtain a preset rule of motion of the diverter 20, for example a rule which includes an initial ramp with constant acceleration and a subsequent final stop with constant deceleration.
  • the diverter From the operating position of figure 6, by reversing the direction of rotation of the motor 26, for example by means of a corresponding reversal of the polarity of the voltage applied thereto, which is produced by the control CE, the diverter can be moved in succession into the second operating position 20y shown in figure 7, in which the thread FT is diverted from the active surface 30b of the pawl 31b in the opposite direction in order to take up and retain the thread, as possibly required by the weaving process.
  • the transition from the active slowing position to the takeup and retensioning position occurs for a single direction of motion, indicated by the arrow in figure 7, of the diverter 20 and can therefore be performed very quickly and with a rule of motion which can be programmed in any fashion.
  • the braking, takeup and retensioning positions can of course be swapped, in that the first one may coincide with the configuration of figure 7 and the second one may coincide with the configuration of figure 6.

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Looms (AREA)
  • Braking Arrangements (AREA)
EP19970114831 1996-09-03 1997-08-27 Weft brake particularly for air-jet looms Expired - Lifetime EP0826806B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO960730 1996-09-03
ITTO960730 IT1284778B1 (it) 1996-09-03 1996-09-03 Freno di trama perfezionato, particolarmente per telai ad aria

Publications (2)

Publication Number Publication Date
EP0826806A1 EP0826806A1 (en) 1998-03-04
EP0826806B1 true EP0826806B1 (en) 2002-11-27

Family

ID=11414869

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19970114831 Expired - Lifetime EP0826806B1 (en) 1996-09-03 1997-08-27 Weft brake particularly for air-jet looms

Country Status (3)

Country Link
EP (1) EP0826806B1 (it)
DE (1) DE69717368T2 (it)
IT (1) IT1284778B1 (it)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITTO980207A1 (it) * 1998-03-12 1999-09-12 Lgl Electronics Spa Dispositivo di frenatura modulata del filato di trama per macchine tessili
IT1303154B1 (it) 1998-07-17 2000-10-30 Lgl Electronics Spa Dispositivo perfezionato di frenatura modulata del filato di trama permacchine tessili.
EP2128318A1 (en) * 2008-05-30 2009-12-02 Iro Ab Take-up device
CN109279450B (zh) * 2018-09-26 2024-04-16 浙江泰和纺织机械有限公司 多用途防断线双向制动纱架

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1188625B (it) * 1986-03-25 1988-01-20 Roy Electrotex Spa Dispositivo smorzatore delle oscillazioni e vibrazioni dei fili di trama in dispositivo alimentatori della trama per telai ad aria
EP0356380B1 (de) * 1988-08-25 1994-11-23 Sulzer RàœTi Ag Verfahren zum Vermeiden von Spannungsspitzen eines Schussfadens beim Schusseintrag während des Bremsvorganges
IT1248716B (it) * 1990-06-11 1995-01-26 Vamatex Spa Dispositivo per la regolazione della tensione ed il recupero del filo di trama in telai di tessitura
BE1005173A3 (nl) * 1991-08-13 1993-05-11 Picanol Nv Draadrem.
DE4131652A1 (de) * 1991-09-23 1993-04-01 Iro Ab Webmaschine und eintragbremse fuer webmaschinen
BE1007898A3 (nl) * 1993-12-22 1995-11-14 Picanol Nv Inrichting voor weefmachines.

Also Published As

Publication number Publication date
DE69717368T2 (de) 2003-09-11
EP0826806A1 (en) 1998-03-04
IT1284778B1 (it) 1998-05-21
DE69717368D1 (de) 2003-01-09
ITTO960730A1 (it) 1998-03-03

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