EP0083748B1 - Method and device of removing a broken weft yarn in a jet loom - Google Patents

Description

The invention relates to a method for removing a defective weft in a fluid jet loom, according to which the weft, the length of which has been measured, is introduced by a fluid flow (jet) from a weft insertion nozzle via a weft cutter into a successively formed weaving machine are formed by alternating upper and lower warp threads, the inserted weft thread is normally cut by the weft thread cutter, and an apparatus for carrying out the method.

In general, in such a loom, the weft is thrown into the shed, which is formed by the warp threads, by a pressurized fluid, such as water or air, which is supplied under pressure from a weft insertion nozzle. With this type of loom, the weft thread must be cut at a connecting portion from the selvedge towards the thread feed whenever a measured length of the weft thread has been thrown into the loom, since the weft thread only enters the loom from one side of the loom frame is thrown or shot.

1 shows a conventional loom in which the weft W is supplied from a weft supply source 31 to a conventional length measuring unit 33 via a tensioning member 32. The weft W, the length of which has been measured, is supplied by means of an air nozzle 34 for weft pooling, a weft pool tube 35, a weft guide 36 and a gripper 37 to a weft insertion nozzle 3, which is fastened to the top of a drawer 1 with a reed 2 , which can perform a swinging movement in a known manner. A pressurized fluid is injected along the weft W towards a guide passage which is formed by a series of guide members 24 which are provided in a predetermined division on the side of the reed 2 towards the woven material edge. A weft cutter 5 is attached near the edge of the woven fabric on the side of the weft insertion nozzle so as to be operated in time with the loom operation. A cutting blade 7 is provided on the opposite side of the cutter 5 to cut the waste selvedge 6. A weft sensor 8 is provided on the drawer 1, on the opposite side of the nozzle 3, in order to detect the insertion of a defective thread or, if applicable, the defective insertion. After the occurrence of such a defect, this is determined by the sensor and the operation of the loom is interrupted. The defective weft thread is removed in this state and the loom operation is started again.

With this conventional loom, it is not possible to stop the loom immediately because the loom works at a higher speed and because of the braking time, even if the defect has been detected by a sensor. It is only possible to stop the loom operation after the defective weft has been knocked against the previously inserted weft. In this state, the defective weft is cut on the side of the nozzle 3 and the next length of the weft is inserted into the shed. Therefore, the removal of the defective weft can only be effected by pulling the weft which has been inserted after the defective weft from the shed. Then the loom frame has to be driven forward or backward by manual operation or by pressing a slow button, after which the upper and lower warp threads are opened for the removal of the defective weft thread.

However, since the defective weft near the selvedge has previously been cut by the cutter 5 and only a small portion of the thread protrudes outside the selvedge, and furthermore the defective weft has been subjected to a striking so as to become part of the woven fabric , it is extremely difficult to remove the defective weft that already belongs to the cloth. It is conventional practice to pull out several points of the defective weft into the shed by using a tapered needle and pulling the weft out of the row of warps, which is only possible through a very tedious and painful process.

From DE-B-22 28 131 a weft search device on a pneumatic jet loom is known. The thread monitor controls the cutting element in such a way that the cutting element is switched off immediately by the false signal of the thread monitor and is switched on again by the thread monitor after the faulty weft thread length has been removed. In this way, the weft that caused the weaving error remains connected to the next weft length and the latter is drawn into the shed when the defective weft length is removed. One is therefore not dependent on the restoration of the normal transport air supply of the main blowing nozzle for the entry of the next weft thread length, whereas the moment in which the main shaft comes to a standstill after the signaling of a weaving error is not critical, but may lie arbitrarily within the next weft phase, eg 270 ° after the time of detection. The cutting will This prevents the cutting gate from being interrupted in terms of its operation by the sensor. However, this requires a relatively complicated control effort, as can be seen in detail from the cited document.

It is therefore the object of the invention to provide a method for removing the defective weft thread in a fluid jet loom, in which the aforementioned disadvantages are avoided and simple removal of the defective weft thread is thus possible.

This object is achieved in accordance with the present invention in that the weft cutting function is temporarily suspended by deflecting the weft from the weft cutting point, substantially immediately after a defective thread insertion is detected and while the insertion of the weft thread into the thread continues Next loom, and that subsequently the loom operation is stopped, whereby the uncut weft thread associated with the defective thread takes a U-shape and runs to the nozzle.

The device solution is characterized in particular by the fact that a weft sensor is provided for detecting a defective weft inserted into the shed, and that a weft deflector is arranged on the weft cutter in order to deflect said weft from its normal cutting position within the weft cutter due to the actuation of the sensor after the presence of a defective weft thread is determined, whereby the weft thread remains uncut.

With this solution, the weft cutting device can continue to be operated in the normal way even when a defective weft insertion is found. The cutting of the thread is prevented simply by temporarily deflecting the weft thread from the path in which the cutting normally takes place at this time. Then the loom is stopped. In this way, the length of the weft located downstream of the weft insertion nozzle in the direction of the weft insertion can be kept to a minimum, so that the amount of the weft to be removed during the removal of the defective weft can be reduced, to thereby considerably promote the thread removal process.

• Fig. 1 eine schematische Draufsicht mit der Darstellung der wesentlichen Teile eines Strömungsmittel-Jet-Webstuhls,
• Fig. 2 eine Seitenansicht mit der Darstellung eines Schußfadenschneiders, welcher beim Praktizieren des Verfahrens gemäß der vorliegenden Erfindung verwendet wird,
• Fig. 3 eine explodierte perspektivische Darstellung des Schußfadenschneiders,
• Fig. 4 eine Seitenansicht zur Erläuterung des Betriebs des Schußfadenschneiders, und
• Fi^g. 5 eine schematische Draufsicht mit der Darstellung des Zustandes des Schußfadeneinsetzens infolge auf das Feststellen eines defekten Schußfadens.

The invention is explained on the basis of the following description. It shows:

• 1 is a schematic plan view showing the essential parts of a fluid jet loom,
• 2 is a side view showing a weft cutter used in practicing the method according to the present invention.
• 3 is an exploded perspective view of the weft cutter,
• Fig. 4 is a side view for explaining the operation of the weft cutter, and
• Fi ^g. 5 is a schematic plan view showing the state of the weft insertion due to the detection of a defective weft.

An embodiment of the invention will now be described with reference to Figs. The fluid jet loom of the invention differs from the conventional device in the construction of a weft cutter 10. On the other hand, the loom according to the invention is the same as that previously described with reference to FIG. 1. Therefore, the same reference numerals designate the same parts or components. A fixed blade 11, directed towards the selvedge, is attached to a fixed support shaft 12 on the machine frame (not shown) and is fixed at the rear end to a fixed shaft 11a which protrudes from the selvedge so that it is rotationally fixed relative to the machine frame is. A movable blade 13 is supported for free rotation by said support shaft 12 and has an arm 13a which runs obliquely downwards in the opposite direction to the cutting edge. This arm 13a carries a drive pin 14. An L-shaped lever 16 is attached by means of an axis 15 for rotation relative to the loom frame. One end of the lever 16 is connected to the movable blade 13 by means of the drive pin 14. The lever 16 is biased by a tension spring 17 for a counterclockwise rotation according to FIG. 2. A cam follower 20 is mounted for rotation about its own axis toward the distal end of the lever 16 and is in rolling contact with a cam 19 which is attached to an axis of rotation 18.

A weft guide 23, which is formed by a cylindrical projection 21 and a triangular guide plate 22, is placed on the support shaft 12 outside the rotatable blade 13. A guide groove 22a is formed on the upper edge of the guide plate 22, while a top hole is formed in the projection 21. The weft guide 23 is fastened to the support shaft 12 by a clamping screw 24, which clamping screw 24 is screwed into the topped hole or threaded hole such that the guide groove 22a is positioned a little above the edge end of the fixed blade 11. A weft deflector 25 is attached to the outside of the weft guide 23 for rotation about the support shaft 12. A weft deflectable portion 25a is provided on the foremost part of the weft deflator 25 for the forward running the guide groove 22a of the guide plate 22 The upper end of the weft deflector 25 is provided with an engaging hole 25b for the engagement of a shoulder 27a on the foremost part of a movable iron core 27 of a solenoid 26 mounted for rotation relative to the loom frame. This solenoid 26 is used in operation when problems occurring during insertion of the weft have been detected by the weft sensor 8.

• Beim Schußfadenschneider 10 befindet sich das Solenoid 26 außer Betrieb und der Schußfadendeflektor 25 ist so positioniert, daß die Oberkante des Schußfaden-Ablenkabschnittes 25a sich auf einem niedrigeren Niveau befindet als die Führungsnut 22a der Führungsplatte 22 der Schußfadenführung 23. Wenn der Webstuhl in diesem Zustand in Betrieb gesetzt und der Schußfaden in das offene Kettfadenwebfach abgelegt wird, wird das Schußfadenende in Richtung auf die Schußfadeneinführdüse 3 in die Führungsnut 22a der Schußfadenführung 23 eingesetzt. Wenn der Nocken 19 zusammen mit dem Drehschaft 18 bei fortgesetztem Webstuhlbetrieb entsprechend Fig. 2 im Uhrzeigersinn gedreht wird, wird der Hebel 16 so lange in fester Lage gehalten, wie der Abschnitt geringeren Durchmessers des Nockens das Nockenfolgeglied 20 berührt. Wenn der Berührungsabschnitt den Abschnitt geringeren Durchmessers passiert hat, wird der Hebel 16 gegen die Kraft der Zugfeder 17 im Uhrzeigersinn gedreht. Wenn der Hebel 16 aus der in ausgezogenen Linien gekennzeichnetm Lage (Fig. 2) in die durch Doppelpunkt-Strich-punktierte Linien gekennzeichnete Lage bewegt wird, wird die drehbare Klinge 13 ebenso aus der durch ausgezogene Linien dargestellten Lage im Gegenuhrzeigersinn in die Lage gedreht, die in Fig. 2 durch Doppelpunkt-Strich-Linien gekennzeichnet ist, um den in der Führungsnut 22a befindlichen Schußfaden zu schneiden. Bei fortgesetzter Drehung des Nockens 19 wird der Hebel 16 unter der Kraft der Zugfeder 17 im Gegenuhrzeigersinn gedreht und in die Ausgangslage zurückgedreht. Die drehbare Klinge 13 wird gleicherweise in die Ausgangslage zurückgedreht. Das Drehen des Nockens 19 ist mit der Schwenkbewegung der Lade 1 synchronisiert, so daß die drehbare Klinge 13 in Schußfadenschneidrichtung gedreht wird, sobald das Riet auf den vorhergehenden Schußfaden schlägt. So wird bei einem normalen Webstuhlbetrieb der Schußfaden für jeden Schußfadeneinführvorgang geschnitten, sobald das Riet auf den vorhergehenden Schußfaden schlägt.

The weft thread cutter 10 of the type thus described operates as follows:

• In the weft cutter 10, the solenoid 26 is out of operation and the weft deflector 25 is positioned so that the upper edge of the weft deflecting portion 25a is at a lower level than the guide groove 22a of the guide plate 22 of the weft guide 23. When the loom is in this state In operation and the weft is placed in the open warp shed, the weft end is inserted in the direction of the weft insertion nozzle 3 in the guide groove 22a of the weft guide 23. 2, the cam 16 is held in a fixed position as long as the smaller diameter portion of the cam contacts the cam follower 20. When the contact portion has passed the smaller diameter portion, the lever 16 is rotated clockwise against the force of the tension spring 17. When the lever 16 is moved from the position indicated by solid lines (FIG. 2) to the position indicated by dash-and-dot lines, the rotatable blade 13 is also rotated counterclockwise from the position indicated by solid lines, which is identified in FIG. 2 by double-dashed lines in order to cut the weft thread located in the guide groove 22a. With continued rotation of the cam 19, the lever 16 is rotated counterclockwise under the force of the tension spring 17 and rotated back into the starting position. The rotatable blade 13 is likewise turned back into the starting position. The rotation of the cam 19 is synchronized with the pivoting movement of the drawer 1, so that the rotatable blade 13 is rotated in the weft cutting direction as soon as the reed strikes the previous weft. In normal loom operation, the weft is cut for each weft insertion process as soon as the reed hits the previous weft.

If a problem or malfunction occurs in the weft insertion process and is detected by sensor 8 during loom operation, solenoid 26 is energized and movable iron core 27 in solenoid 26 is retracted against the force of a spring in solenoid 26. The weft deflector 25 is rotated into a position shown in FIG. 4, in which the upper edge of the deflection section 25a is at the same level as the upper edge of the guide plate 22. In this state, the end of the inserted weft thread is not inserted into the guide groove 22a of the weft thread guide 23 when the drawer 1 is swung toward the woven goods edge, but rides on the upper edge of the deflecting portion 25a. Thus, when the drawer 1 is rotated in a direction away from the edge of the woven fabric after the reed is opened, the weft end slides on the upper edge of the weft deflecting portion 25a and is not detected at the cutting point, i.e. on the guide groove 22a so that the weft thread is not cut despite rotation of the rotatable blade 13.

In this way, in the fluid jet loom provided with the weft cutter 10, the weft deflector 25 is energized by the solenoid 26 immediately after the weft sensor 8 detects the malfunction of the weft insertion during the loom operation to prevent the weft cutter 10 from cutting the weft do. The weft inserted after the defective weft has been struck and until the loom stops has the shape of a U, with one end hanging on the defective weft, as shown in FIG. Thus, the defective weft can be pulled out by pulling the weft inserted in the form of the U while the loom is slowly operated by manual operation in the reverse direction, or by actuating a push button which interacts with a slow movement device. In this way, the complicated process of removing the defective weft thread according to the conventional practice can be avoided. The pulling out of the weft thread can also be effected by suction using a suitable air suction gun.

To prevent the weft cutting operation of the weft cutter 10, the weft can be deflected from the weft guide 23 by means of a direct operation from the solenoid, so that the weft deflector 25 can be omitted.

From the above description, it can be seen that the weft cutting function of the weft cutter provided for the weft insertion nozzle can be temporarily disabled after detection of the malfunction in the weft insertion and subsequently the loom operation is stopped while the weft section which is inserted next is uncut and with the defective thread remains connected to promote easy and comfortable pulling out of the defective weft thread. Thus, a complicated manual operation for pulling out several points of the defective weft into the warp shed by using a tapered needle can be prevented, as was required by the conventional device. The defective thread can be removed by simply pulling the easily accessible, uncut weft section, which is related to the defective thread.

Claims (5)

1. Process for removal of a defective weft thread from a flow-medium jet loom, according to which the weft thread, whose length has been measured, is inserted into successive sheds, which are formed by alternate upper and lower warp threads, by a flow-medium current (jet) from a weft tnread insertion nozzle by way of a weft thread cutter, the inserted weft thread normally being cut by the weft thread cutter, characterised in that the weft thread cutting function is temporarily interrupted, by deflecting the weft thread from the weft thread cutting point substantially immediately after the detection of a defective thread insertion and while continuing the insertion of weft threads into the next shed, and that operation of the loom is subsequently stopped, whereby the uncut weft thread joined to the defective thread assumes a U-shape and runs out to the nozzle.

2. Process according to claim 1, characterised in that the weft thread is deflected from the cutting point by being prevented from attaining a guide groove in which the weft thread is normally positioned for cutting per se.

3. Process according to claim 2, characterised in that deflection takes place by positioning a deflection edge substantially transverse of the groove and sliding the weft thread away from the cutting point along the deflection edge.

4. Flow-medium jet loom, in which a weft thread, whose length has been measured, is inserted by a flowmedium jet from a weft thread insertion nozzle into successively-formed sheds, which sheds are so formed that the upper and lower warp threads are alternate with one another, the inserted weft thread normally being cut by a weft thread cutter, characterised in that a weft thread sensor (8) is provided for detecting a defective weft thread inserted into the shed and that a weft thread deflector (25) is arranged on the weft thread cutter (10), in order to deflect such a weft thread from its normal cutting position inside the weft thread cutter, by actuation of the sensor after the detection of the presence of a detective weft thread, whereby the weft thread remains uncut.

5. Loom according to claim 4, characterised in that the weft thread cutter (10) has a fixed blade (11), a movable blade (13) and a guide plate (22), which is arranged in a fixed position adjacent the fixed blade (11) and has means for forming a weft thread receiving groove (22a) for guiding the weft thread between the fixed and movable blades, and that the deflection means include a weft thread deflector (25) which is secured for rotational movement with the guide plate and has an edge (25a) which prevents the weft thread from attaining the guide plate groove (22a), through rotational movement of the deflector, and that solenoid means are actuable under the control of the sensor means to rotate the weft thread deflector.

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