Device for forming a leno weave in a weaving machine

Abstract

The invention relates to a device for forming a leno weave in a weaving machine, the device comprising an endless support element (6) guided along an elongated endless path and a thread guide (7) mounted to the endless support element (6), wherein the endless support element (6) is supported by pulleys (9, 10), and wherein the thread guide (7) is adapted to guide the leno thread towards a fabric (8), wherein the thread guide (7) is provided with a first section (72) for mounting the thread guide (7) to the endless support element (6), the first section (72) extending at the inner side of the endless support element (6), and the pulleys (9, 10) are provided with recesses (90, 100), wherein the endless support element (6) and the pulleys (9, 10) are adapted to each other so that when the endless support element (6) circulates, the first section (72) is received in the recesses (90, 100) of the pulleys (9, 10). The invention further relates to a weaving machine comprising such a device, and a method for manufacturing such a device.

Description

Technical Field

[0001] The invention relates to a device for forming a leno weave in a weaving machine, and to a weaving machine comprising such a device. The invention further relates to a method for manufacturing such a device. Background Art

[0002] The term leno weave describes a weave in which the leno threads (also called leno binder threads or leno warp threads) are twisted around the weft threads.

[0003] US3698441 shows a device for forming a leno selvedge, comprising at least two thread guides mounted to an annular support element guided along an elongated annular path for guiding a corresponding number of leno threads from a leno thread supply to a fixed joining point. Summary of the invention

[0004] The object of the present invention is to provide a device for forming a leno weave, the device comprising an annular support element having a long service life and at least one pair of thread guides securely mounted thereto.

[0005] According to a first aspect of the present invention, a device for forming a leno structure is provided, the device comprising an annular support element guided along an elongated annular path and a wire guide mounted to the annular support element (particularly a pair of wire guides distributed along the annular support element), wherein the annular support element is supported by a pulley, wherein the wire guide is suitable for guiding the leno thread toward the fabric, wherein the wire guide is provided with a first section for mounting the wire guide to the annular support element, the first section extending at the inner side of the annular support element, wherein the pulley is provided with a recess, and wherein the annular support element and the pulley are adapted to each other so that when the annular support element circulates, the first section is received in the recess of the pulley.

[0006] Throughout the application and claims, the indefinite article "a" or "an" means "one or more". Reference to a "first element" does not require the presence of a "second element". Further, the expressions "first" and "second" are only used to distinguish one element from another, but do not indicate any order of these elements.

[0007] In a preferred embodiment, the thread guide is provided with a clamp having a first section extending at the inner side of the annular support element and a second section extending at the outer side of the annular support element.

[0008] In the context of the present application, a fixture is defined as an element with two sections, between which the annular support element is inserted. Using a fixture allows the thread guide to be securely fixed to the annular support element, because the thread guide has a large contact surface with the annular support element. Thus, damage to the annular support element during installation and use of the thread guide can be avoided. When using the fixture, one section of the fixture extends along the inner side of the annular support element, which is in contact with the pulley. According to the present application, at each cycle of the annular support element, the section is received in a recess or in one of a plurality of recesses to ensure smooth guidance of the annular support element and the thread guide along the pulley.

[0009] In one embodiment, two or more pulleys with parallel rotation axes are provided, wherein, in particular, each pulley is provided with one or more notches.

[0010] In one embodiment, a pair of thread guides for forming a leno weave is provided, wherein, in particular, in one embodiment, these thread guides are evenly distributed along the annular support element. In other embodiments, two pairs of thread guides are provided, wherein, in particular, in one embodiment, all thread guides are evenly distributed along the annular support element.

[0011] In one embodiment, the annular support element inserted between the two segments of the clamp forces the segments apart against the internal restoring force, so that the annular support element is held between the two segments of the clamp by the restoring force. In an alternative or in addition, in one embodiment, the clamp is fixed to the annular support element using a fixing wire or using a U-shaped fixing element, the fixing wire having a base and two bendable legs, and the U-shaped fixing element having two legs, each leg having a thread for cooperating with a nut. In one embodiment, the segments of the clamp and the annular support element are provided with through holes for receiving the two legs. In an embodiment, the fixing wire or the U-shaped fixing element is inserted from the inside of the annular support element, so that the base is arranged at the inside of the annular support element and the legs are inserted in the through holes of the clamp and the annular support element, wherein, in order to fix the clamp, at the outside of the annular support element, the bendable legs are bent, in particular towards each other and towards the annular support element, or the legs with threads are fixed by using a nut. The base of the fixing wire or the fixing element protrudes from the inner side of the ring-shaped support element, wherein, in particular, the height and width of the protruding section of the clamp together with the base are smaller than the depth and width of the one or more recesses of the pulley.

[0012] In one embodiment, the pulley is provided with only one notch, wherein the first section of the thread guide (or the first section of each thread guide if two or more thread guides are provided) is received in said notch when the ring-shaped support element circulates. In other embodiments, the pulley is provided with more than one notch. In this case, in one embodiment, the first section of the thread guide (or the first section of each thread guide if two or more thread guides are provided) is received in an associated notch of said plurality of notches when the ring-shaped support element circulates.

[0013] In one embodiment, the pulley is provided with a pulley disc, wherein the pulley disc has an opening suitable for receiving a wire guide (particularly for receiving one or two wire guides in the pair of wire guides) when the annular support element circulates, wherein the opening is aligned with the notch in the circumferential direction of the pulley. If the pulley is provided with more than one notch, the opening is aligned with the notch of the first segment receiving the wire guide. In other words, in this case, the opening is aligned with one of the notches in the plurality of notches. In an embodiment, the number of openings is minimized to avoid weakening and irregular outer contours of the pulley disc. In an embodiment, two or more wire guides are provided. If the first segments of all wire guides are received in a common notch, the pulley disc can be provided with only one opening, which is aligned with the notch in the circumferential direction of the pulley. If the first segments of different wire guides are received in different notches, the pulley disc is provided with a corresponding number of openings, each of which is aligned with one of the notches in the circumferential direction of the pulley. In one embodiment, two pulley discs are provided at either end of the pulley, and each pulley disc is provided with an opening. In other embodiments, only one pulley disc is provided. If several pulleys are provided, then in one embodiment, all pulleys are provided with pulley discs. In other embodiments, only one pulley (particularly the driving pulley) is provided with a pulley disc.

[0014] In one embodiment, the endless support element is a toothed belt with a series of evenly distributed teeth, in which one tooth is missing, wherein the thread guide is mounted to the toothed belt in the place of the missing tooth. In one embodiment, two teeth are missing from the series of teeth, wherein two thread guides are mounted to the toothed belt in the place of the two missing teeth. In one embodiment, the toothed belt is manufactured with several missing teeth. In other embodiments, several teeth of the toothed belt are removed and the thread guide is mounted (in particular clamped) to the toothed belt in place of these removed teeth. When properly tensioned, the toothed belt does not slip. This allows the movement of the thread guide to be reliably synchronized with the main drive of the loom.

[0015] In one embodiment, the teeth are rounded and in particular have a semicircular shape. The rounded, in particular semicircular shape enables the teeth to smoothly engage and disengage with the pulley and thus allows the toothed belt to move at high speeds. The teeth may also have another rounded or curved shape.

[0016] In one embodiment, the pulley is provided with a number of evenly distributed notches, wherein the number of teeth of the toothed belt, including the missing teeth, is an integer multiple of the number of notches of the drive pulley, in particular an odd integer multiple of the number of notches. If the number of teeth is an integer multiple of the number of notches, each thread guide is received in an associated notch at each cycle of the toothed belt. If the number of teeth, including the missing teeth, is an even integer multiple of the number of notches of the pulley, all thread guides in a pair of evenly distributed thread guides are received in the same notch. If the number of teeth, including the missing teeth, is an odd integer multiple of the number of notches of the pulley, wherein, for example, the odd integer multiple is equal to three, the thread guides in a pair of evenly distributed thread guides are received in two notches displaced by 180°. In one embodiment, all notches are identical in design. In other embodiments, the pulleys are each provided with: a first recess adapted to receive a first section of a wire guide or teeth of a toothed belt; and a plurality of second recesses adapted only to receive teeth of a toothed belt, wherein the number of teeth, including the missing teeth, is an integer multiple of the total number of the first recesses and the second recesses.

[0017] The thread guide is provided with a thread eye, to which the leno thread is threaded in use for guiding the leno thread from the thread supply toward the fabric, particularly toward the weft line of the fabric and / or the edge of the fabric (e.g., the edge at one side of the fabric). In an embodiment, the thread guide is provided with a thread eye with a wear-resistant surface. In one embodiment, the thread guide is made of a wear-resistant material and / or is provided with a wear-resistant coating in the region of the thread eye. In another embodiment, a hollow insert made of a wear-resistant ceramic material is mounted to the thread guide and used as a thread eye. In one embodiment, the thread guide made of ceramic material (also referred to as a ceramic thread guide) has a shape as shown in JPH06-184871 (the contents of which are incorporated herein by reference). This thread guide allows simple threading.

[0018] In one embodiment, the thread guide is L-shaped, having a first end provided with a guide eye and a second end provided with a first section, wherein the first end and the second end are arranged at an angle to each other, wherein, in particular, the angle between the first end and the second end is greater than 90°. By arranging the first end and the second end at an angle greater than 90° to each other, the distance of the guide eye from the annular support element is increased.

[0019] In one embodiment, at least one line detector is provided for detecting the absence and / or presence of a line to be guided by the thread guide. In one embodiment, the at least one line detector is a contactless line detector (in particular an optical detector) using a transmitter for sending a signal and a receiver for receiving a signal, wherein the presence of the leno line causes an interruption of the signal. In an alternative or in addition, a line detector comprising a piezoelectric element is provided. In one embodiment, the piezoelectric element is mounted to the distal end of the rotating axis of the pulley, wherein, by means of the piezoelectric element, it is possible to detect whether the leno line guided by the guide eye of the thread guide passes along the piezoelectric element. In an alternative embodiment, a piezoelectric element is provided near the guide eye of the thread guide, wherein the detected signal is transmitted wirelessly to a control unit.

[0020] In one embodiment, the pulley is a driving pulley, which is drivingly coupled to a motor, in particular an electric motor, wherein the motor is synchronized to the loom. For example, the motor can move in any direction and be synchronized to the loom. In addition, the device includes at least one second pulley (i.e., a driven pulley), wherein the rotation axes of these pulleys are arranged in parallel. In one embodiment, the second pulley is identical to the first pulley in design. In other embodiments, the second pulley is different in design, for example, having a smaller or larger diameter and a different number of recesses resulting therefrom, wherein each time the thread guide passes through the driven pulley, the first section of the thread guide is received in different recesses. In one embodiment, a tubular motor is provided, which is directly coupled to the driving pulley. In other embodiments, the driving pulley is coupled to the motor via a shaft, which in one embodiment is accommodated in a shaft housing.

[0021] In one embodiment, a sensor fixed in position is provided, which is suitable for providing a signal when the thread guide passes through the sensor. In one embodiment, the sensor is a Hall sensor, and the thread guide is at least partially made of magnetizable material, particularly made of steel. In an alternative embodiment, the sensor is a proximity switch, which generates a signal when the thread guide is near the proximity switch. In one embodiment, the sensor is used to synchronize the movement of the thread guide to the loom, wherein, for example, the sensor signal is transmitted to a control unit, and this control unit controls the motor that is connected to a drive pulley.

[0022] In one embodiment, a pair of thread guides are mounted to the annular support element, wherein the thread guides of the pair are distributed, in particular evenly distributed, along the annular support element. In an embodiment of the invention, all thread guides of the device are provided with a clamp and are mounted to the annular support element using the clamp.

[0023] According to a second aspect, there is provided a weaving machine comprising a device for forming a leno weave as described above. In one embodiment, at least two devices for forming a leno weave are provided, which devices are arranged at opposite sides of the fabric for forming a selvedge.

[0024] According to a third aspect, there is provided a method for manufacturing an apparatus for forming a leno weave, the apparatus comprising an endless support element and a thread guide mounted to the endless support element, wherein the thread guide is fixed to the endless support element by a clamp having two sections, so that the two sections of the clamp of the thread guide extend at opposite sides of the endless support element. In an embodiment of the invention, the endless support element is a toothed belt, wherein one tooth of the toothed belt is removed, and the thread guide is fixed to the endless support element at the position of the removed tooth. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Throughout the accompanying drawings, the same elements will be represented by the same reference numerals. In the schematic drawings,

[0026] Figure 1 A first embodiment of a device for forming a leno weave in a weaving machine is shown in a perspective view.

[0027] Figure 2 It is in magnified proportion Figure 1 Detail perspective view.

[0028] Figure 3 Shown in perspective Figure 1 An annular support element of the device together with a wire guide mounted thereto.

[0029] Figure 4 The previous view shows Figure 3 annular support element.

[0030] Figure 5 It is in magnified proportion Figure 4 Details of V.

[0031] Figure 6 Is installed to Figure 3 A top view of the wire guide of the annular support element.

[0032] Figure 7 Is installed to Figure 6 A cross-sectional view of a wire guide having an annular support element.

[0033] Figure 8 yes Figure 1 A perspective view of the lower portion of the device showing the drive pulley.

[0034] Fig. 9 is shown similar to Figure 1 A cross-sectional view of a driven pulley and a sensor of a second embodiment of a device.

[0035] Fig.10 A third embodiment of a device for forming a leno weave in a weaving machine is shown in a perspective view. DETAILED DESCRIPTION

[0036] Figure 1 A device 1 according to the invention is shown, in which two leno threads 2, 3 are alternately raised and lowered to form a leno weave by twisting the leno threads 2, 3 around each other in order to incorporate a weft thread 4 into the leno threads 2, 3. The device 1 is to be arranged on a weaving machine, such as a rapier weaving machine, an air jet weaving machine or any other kind of weaving machine, in which Figure 1 The reed 5 of the weaving machine is only schematically shown. Figure 2 It is in magnified proportion Figure 1 Detail perspective view.

[0037] In one embodiment, the device 1 is arranged in the outer edge region of the fabric 8 (for example, on the outer edge at the weft insertion side of the fabric or at the outer edge at the opposite side of the fabric), or in the central region of the loom for producing a leno weave between two fabrics. In one embodiment, two or more devices 1 are arranged side by side on the outer edge of the fabric.

[0038] For moving the leno threads 2 , 3 , the device 1 comprises an annular support element 6 and a pair of thread guides 7 evenly distributed mounted to the annular support element 6 , wherein each thread guide 7 is adapted for guiding the leno threads 2 , 3 between a thread supply (not shown) and a fabric 8 .

[0039] The device further comprises a driving pulley 9 and a driven pulley 10 having parallel axes 94, 104, wherein the driving pulley 9 and the driven pulley 10 are jointly referred to as pulleys 9, 10. When mounted to the loom, in the embodiment shown, the axes 94, 104 of the pulleys 9, 10 are arranged parallel to the pulling direction of the warp and leno threads (as indicated by the axis 94, 104 of the pulleys 9, 10). Figure 1 ), this pulling direction is also called the warp direction or leno direction.

[0040] The endless support element 6 is supported by two pulleys 9 , 10 and the thread guide 7 is guided along an elongated endless path, whereby the leno threads 2 , 3 guided by the thread guide 7 are twisted around each other to incorporate the weft thread 4 into the leno threads 2 , 3 .

[0041] In one embodiment, the thread supply for the leno threads 2, 3 comprises a fixedly arranged bobbin (not shown), wherein the annular support element 6 is driven to move several turns in one direction and then driven to move several turns in the opposite direction in order to avoid excessive twisting of the leno threads 2, 3 in the area opposite to the fabric (i.e., the rear area of ​​the loom).

[0042] In another embodiment, the thread supply for the leno threads 2, 3 comprises a rotatably arranged bobbin (not shown), as known for example from US Pat. No. 3,698,441, wherein the annular support element 6 can be driven to move in one direction only.

[0043] The drive pulley 9 (which in the embodiment shown is the lower pulley) is driven by an electric motor 11 which is controlled independently of the main drive of the loom (not shown) and the drive of the shed device (not shown). In one embodiment, the electric motor 11 is a stepper motor which is electrically controlled and can be driven in both directions of rotation. In one embodiment, the stepper motor is controlled in open loop. In an alternative or in addition to the open loop control, a position sensor 17 (see Fig. 9 The signal of the stepper motor 1 (described in more detail below) can be used for feedback control of the position of the stepper motor. In one embodiment, the synchronization of the device 1 and the loom is set and controlled according to a program so that the leno threads 2, 3 move and cross each other at the expected moment in the weaving cycle. In an embodiment, the drive pulley 9 is a lower pulley. The drive pulley 9 uses a shaft 24 (see FIG. 1 ) housed in the shaft housing 12. Figure 8 ) is connected to the electric motor 11.

[0044] The shaft housing 12 further acts as a support for the housing 13 of the pulleys 9, 10. In the embodiment shown, two fixed guide elements 14 are mounted on the housing 13 of the pulleys 9, 10, each guide element 14 comprising a bent wire. In an alternative embodiment, the two guide elements are formed integrally. The leno threads 2, 3 are threaded through an opening in the housing 13 and are guided to the thread guide 7 via the guide elements 14. By means of the guide elements 14, the leno threads 2, 3 from the thread supply are avoided from contacting the annular support element 6 and / or the pulleys 9, 10, in particular when the thread guide 7 is in the upper position or in the lower position. In one embodiment, an additional guide element (not shown), such as a round wire, is provided near the opening in the housing 13 (through which the leno threads 2, 3 are threaded) to avoid the leno threads 2, 3 from contacting the opening in the housing 13 and possibly being damaged by the housing 13.

[0045] The housing 13 is further provided with a fitting 15 for connection to an air supply (not shown), wherein the fitting 15 is connected to a blower 18 adapted to blow away dust that would accumulate in the vicinity of one of the pulleys 9, 10. Figure 2 In the embodiment shown, two such blowers 18 are shown. In an alternative embodiment, two blowers distributed in the vertical direction are provided, one near the driven pulley 10 (which is the upper pulley in the embodiment shown) and one near the driving pulley 9 (which is the lower pulley in the embodiment shown). In other embodiments, only one blower is provided.

[0046] On the front side of the housing 13, as shown Figure 2 As can be best seen in the drawing, two at least substantially vertical bars 19 are provided in order to prevent the operator from getting caught in the moved annular support element 6 and / or the thread guide 7 .

[0047] The endless supporting element 6 is an endless toothed belt in the embodiment shown, and the pulleys 9, 10 are provided with several evenly distributed recesses 90, 100 which are suitable for accommodating the teeth 60 of the toothed belt.

[0048] Figures 3 to 8 The ring-shaped support element 6 together with the wire guide 7 mounted thereto are shown in perspective view, front view, enlarged scale, top view and cross-sectional view, respectively.

[0049] like Figure 3 , Figure 6 and Figure 7 As best seen in the drawings, the thread guides 7 are each provided with a first end having a thread guide eye 70 and a second end having a clamp 71 for clamping the thread guide 7 to the annular support element 6. The clamps 71 each have a first section 72 and a second section 73, wherein the annular support element 6 is inserted between the first section 72 and the second section 73. When clamping the thread guide 7 to the annular support element 6, the clamp 71 at least brings the inner side of the annular support element 6 into contact with the first section 72 and the outer side of the annular support element 6 into contact with the second section 73. Thus, the clamp 71 has a large contact surface with the annular support element 6, so that the annular support element 6 is not damaged by the clamp 71 during fixing and, and even more importantly, during operation of the device 1.

[0050] In the embodiment shown, the clamps 71 are each fixed to the annular support element 6 using a fixing wire 16 having a base 160 and two bendable legs 161. Figure 7 , the two segments 72, 73 of the clamp 71 and the annular support element 6 are, for example, each provided with two through holes 74, 64 for receiving the two legs 161 of the fixing wire 16. The fixing wire 16 is inserted from the inner side of the annular support element 6 so that the base 160 is arranged at the inner side of the annular support element 6 and the legs 161 are inserted into the through holes 74, 64 of the clamp 71 and the annular support element 6. After insertion, the distal ends of the legs 161 are bent toward each other and toward the annular support element 6.

[0051] The yarn guide eye 70 protrudes from the front of the annular support element 6. The thread guides 7 are each L-shaped, having a first end provided with the yarn guide eye 70 and a second end provided with a clamp 71, the first end and the second end being arranged at an angle relative to each other, the angle preferably being greater than 90°, for example an angle between 100° and 110°, thereby increasing the distance of the yarn guide eye 70 from the annular support element 6.

[0052] In the embodiment shown, the hollow insert 75 is made of, for example, a wear-resistant ceramic material (see Figure 7 ) is mounted to the thread guide 7 and serves as a thread guide eye 70. The hollow insert 75 is provided with funnel-shaped inlet and outlet areas for smooth guiding of the leno threads 2, 3.

[0053] In the embodiment shown, the endless support element 6 is a toothed belt having a series of evenly distributed teeth 60, in which two teeth are missing. Two thread guides 7 are mounted to the endless support element 6 in the place of these missing teeth.

[0054] like Figure 5 As shown in the figure, the first section 72 of the clamp 71 is arranged at the inner side of the annular support element 6, and the first section 72 and the base 160 of the fixing wire 16 protrude from the inner side of the annular support element 6. In the embodiment shown, the total height and total width of the first section 72 and the base 160 are smaller than the height and width of the teeth 60, thereby allowing the first section 72 and the base 160 to be pulled by the pulleys 9, 10 (see Figure 1 and Figure 2 ) is received by the recesses 90, 100 of the first section 72, while avoiding the first section 72 and the base 160 from contacting the recesses 90, 100. This helps to reduce wear.

[0055] In the embodiment shown, the number of teeth 60 of the annular support element 6, including the missing teeth, is an odd integer multiple of the number of notches 90 of the drive pulley 9. Thus, when the annular support element 6 circulates, the first sections 72 of the clamps 71 of two evenly distributed thread guides 7 are each received in an associated notch 90 of the drive pulley 9, wherein the two associated notches are displaced by 180°. In the embodiment shown, as Figure 4As best seen in , the toothed belt has a series of forty-two teeth, of which forty teeth are present and two teeth are missing, wherein the thread guide 7 is mounted in the position of the missing teeth. In this exemplary embodiment, the pulleys 9 and 10 each have fourteen notches, so that the ratio of teeth / notches is equal to three. In this embodiment, several teeth 60 of the annular support element 6 always engage with the notches 90 of the drive pulley 9, so that slippage is avoided and reliable synchronization with the loom can always be obtained. The number of teeth and notches is only an example. The toothed belt can also have another series of tooth numbers, preferably an even number of teeth, for example forty-eight teeth, therefore forty-six teeth and two missing teeth. In this case, for a ratio of three, the pulleys 9, 10 each have sixteen notches.

[0056] An odd integer multiple (e.g. a tooth / notch ratio equal to three) provides the following advantages: sufficient shed between the leno threads 2, 3 can be obtained, and the rotation speed of the drive motor 11 remains quite low. In typical use, the annular support element 6 moves more than half a turn during each weaving cycle, so that in the example of a ratio of three, the drive motor 11 will rotate 1.5 turns during each weaving cycle. Due to this, the rotation speed of the drive motor 11 allows to easily start, stop or reverse the direction of rotation of the drive motor 11.

[0057] An even integer multiple (e.g. a tooth / notch ratio equal to four) may provide the following advantages: The advantage that the drive motor 11 may be more easily controlled. In this example, the drive motor 11 rotates two revolutions per weaving cycle, so that after each weaving cycle the drive motor 11 reaches the same position again, which allows easier control of the drive motor 11, in particular when the motor 11 is controlled in two different directions of rotation.

[0058] Figure 8 yes Figure 1 A perspective view of the lower part of the device 1 of FIG. 1 shows the drive pulley 9 together with the annular support element 6 and the thread guide 7 fixed thereto. Figure 8 As shown in , the drive pulley 9 is provided with two pulley discs 91, 92 in the embodiment shown. As explained above, in the embodiment shown, at each cycle, the first section 72 of the clamp 71 of each thread guide 7 is received in an associated recess 90. In the case of the above ratio equal to three, then during each subsequent cycle of the annular support element 6, each thread guide 7 will be received by one of the two recesses displaced by 180°. In order to avoid interference of the thread guide 7 with the pulley discs 91, 92, the pulley discs 91, 92 are provided with two openings 93, which are aligned with the associated recesses 90 in the circumferential direction. As shown in FIG. Figure 1 and Figure 2As shown in, the driven pulley 10 is not provided with any pulley disc in the embodiment shown. In an alternative embodiment, the driven pulley 10 is also provided with pulley discs, wherein these pulley discs are also provided with openings to avoid interference with the thread guide 7.

[0059] exist Figure 8 In the embodiment shown in , a leno thread detector 20 is provided, for example a piezoelectric element, which is mounted between the hollow insert 75 and the segment 76 of the thread guide 7. With the help of the piezoelectric element 20, it can be detected whether a leno thread 3 is present in the thread eye 70 of the thread guide 7 and is guided by it, because such a leno thread 3 causes vibrations on the piezoelectric element 20. Such detected signals can be transmitted wirelessly to the control unit. In other embodiments, other thread detectors are provided, for example a thread detector with a drop wire as used in a warp stop motion. In an alternative embodiment, for example a piezoelectric element is used for this purpose, which contacts the leno thread when it passes along the piezoelectric element and is mounted to the distal end of a shaft 24 driven by a motor 11, which serves as a rotation axis of a pulley 9. In an alternative embodiment, the thread detector can be arranged near the thread supply (in particular near the thread bobbin) to detect whether the leno thread is output (taken off) from the bobbin.

[0060] Fig. 9 is a cross-sectional view of the upper part of a second embodiment of a device 1 for forming a leno weave in a weaving machine, which is similar to Figure 1 For identical or similar elements, reference is made to the above description. Fig. 9 A driven pulley 10 and a sensor 17 are shown, which is adapted to give a signal each time the thread guide 7 passes the sensor 17. The sensor 17 is mounted to the housing 13 of the device 1 in a manner fixed in place, wherein in the embodiment shown the sensor 17 is mounted to detect the absence or presence of the thread guide 7 in the uppermost position. The sensor 17 is, for example, a Hall sensor, which may be small and adapted to detect the thread guide 7 or a portion of the thread guide 7 made of metal passing along the sensor 17. In one embodiment, the signal of the sensor 17 is used to provide position information to a control unit (not shown), which is used to control the electric motor 11 (see FIG. 1 ) driving the ring-shaped support element 6. Figure 1 ) is controlled to be synchronized with the loom.

[0061] like Fig. 9 As shown in , in an embodiment, the driven pulley 10 is mounted on a shaft 22 via a bearing 23 so as to be rotatable about the shaft 22, wherein the shaft 22 is arranged in a fixed position in the housing 13. In other embodiments, the shaft 22 is rotatably mounted in the housing 13 and the pulley 10 is fixed to the shaft 22. The shaft 24 can be mounted in the housing 13 in a manner similar to the shaft 22.

[0062] Fig.10 A third embodiment of a device 1 for forming a leno weave in a weaving machine is shown in a perspective view, which is similar to Figure 1 For the same or similar elements, reference is made to the above description. Figure 1 In contrast to the embodiment shown in , two sensor devices are provided, namely: a sensor 17, such as a Hall sensor, which is suitable for giving a signal each time the thread guide 7 passes the sensor 17; and a thread detector 21, which is used to detect the absence and / or presence of the leno threads 2, 3. In the embodiment shown, the thread detector 21 is a non-contact thread detector, which includes a transmitter 210 and a receiver 212, which are respectively attached to two vertical rods 19. In use, the transmitter 210 sends a signal and the receiver 212 receives the signal, wherein the presence of the leno threads 2, 3 between the transmitter 210 and the receiver 212 causes a measurable interruption of the signal. When the thread guide 7 is moved by the annular support element 6, the thread detector 21 allows monitoring whether the leno threads 2, 3 pass through the thread detector 21. The sensor 17 and the thread detector 21 can be used in combination to verify that the leno threads 2, 3 are present and the signal of the thread detector 21 is interrupted just before the thread guide 7 reaches its uppermost position (which position is detected by the sensor 17) and / or to verify that the leno threads 2, 3 are present and the signal of the thread detector 21 is interrupted just after the thread guide 7 has left its uppermost position (which position is detected by the sensor 17).

[0063] In the embodiment shown, the driving pulley 9 and the driven pulley 10 have notches 90, 100 of the same size and number. In an alternative embodiment (not shown), the lower pulley can have a larger diameter and a greater number of notches than the upper pulley. This allows the leno threads to cross each other closer to the lower pulley than to the upper pulley. If the upper pulley is the driven pulley, the number of notches of the upper pulley can be chosen independently of the number of teeth of the toothed belt, wherein the driving pulley ensures correct timing. Figures 1 to 10 In the embodiment of the annular support element 6, the annular support element 6 is supported by two pulleys 9, 10. In an alternative embodiment, the annular support element may be supported by more than two pulleys, for example three pulleys, one of which is a driving pulley and the others are driven pulleys.

[0064] exist Figures 1 to 10In the embodiment of the present invention, two thread guides 7 are shown which are evenly distributed along the annular support element 6. In an alternative embodiment, several pairs of thread guides 7 may be provided, which are preferably evenly distributed along the circumference of the annular support element 6. In another alternative embodiment, three thread guides may be arranged along the annular support element, wherein, during each weaving cycle, the drive motor 11 is controlled so that a shed between the leno threads 2, 3 can be obtained, wherein one leno thread is in the upper position and the other two leno threads are in the lower position, or wherein one leno thread is in the lower position and the other two leno threads are in the upper position. In yet another alternative, four thread guides may be arranged evenly distributed along the annular support element, or two pairs of thread guides may be arranged next to each other and evenly distributed along the annular support element.

[0065] In an embodiment (not shown), a button is provided, which is connected to the control unit controlling the motor 11. In one embodiment, the button is mounted in an easily accessible position, for example at the bottom of the front of the housing 13 of the device 1. In an alternative or in addition, the button can be integrated in a display connected to the control unit. In order to allow the operator to easily provide the device 1 with a leno thread, the operator can push the button briefly. The signal of the button then controls the motor 11 so that the control unit brings the thread guide 7 to an easily accessible threading position. If the operator, for example, provides new untwisted leno threads 2, 3, the operator can press the button for a long time so that the number of twists of the leno threads 2, 3 stored in the control unit is reset to zero.

Claims

1. A device for forming a leno weave, the device comprising an annular support element (6) guided along an elongated annular path and a thread guide (7) mounted to the annular support element (6), wherein: The annular support element (6) is supported by pulleys (9, 10), and wherein the guide (7) is suitable for guiding the leno thread towards the fabric (8), characterized in that the guide (7) is provided with a first section (72) for mounting the guide (7) to the annular support element (6), the first section (72) extending at the inner side of the annular support element (6), and the pulleys (9, 10) are provided with recesses (90, 100), wherein the annular support element (6) and the pulleys (9, 10) are adapted to each other so that when the annular support element (6) circulates, the first section (72) is received in the recesses (90, 100) of the pulleys (9, 10).

2. The device for forming a leno weave according to claim 1, characterized in that: The thread guide (7) is provided with a clamp (71) having a first section (72) extending at the inner side of the annular support element (6) and a second section (73) extending at the outer side of the annular support element (6).

3. The device for forming a leno weave according to claim 2, characterized in that: The clamp (71) is fixed to the annular support element (6) by using a fixing wire (16) having a base (160) and two bendable legs (161) or by using a U-shaped fixing element having two legs, each leg having a thread for cooperating with a nut.

4. The device for forming a leno weave according to claim 1, 2 or 3, characterized in that: The pulley (9) is provided with pulley discs (91, 92), wherein the pulley discs (91, 92) have openings (93) suitable for receiving the wire guide (7) when the annular support element (6) circulates, wherein the openings (93) are aligned with the recesses (90, 100) in the circumferential direction of the pulley (9).

5. The device for forming a leno weave according to claim 1, 2 or 3, characterized in that: The endless support element (6) is a toothed belt having a series of evenly distributed teeth in which one tooth is missing, wherein the thread guide (7) is mounted to the toothed belt in the position of the missing tooth.

6. The device for forming a leno weave according to claim 5, characterized in that: The teeth (60) are circular.

7. The device for forming a leno weave according to claim 5, characterized in that: The teeth (60) have a semicircular shape.

8. The device for forming a leno weave according to claim 5, characterized in that: The pulleys (9, 10) are provided with a plurality of evenly distributed notches (90, 100), wherein the number of teeth (60) of the toothed belt including the missing teeth is an integer multiple of the number of notches (90, 100) of the pulleys (9, 10).

9. The device for forming a leno weave according to claim 8, characterized in that: The number of teeth (60) of the toothed belt, including the missing teeth, is an odd integer multiple of the number of the notches (90, 100).

10. The device for forming a leno weave according to claim 1, 2 or 3, characterized in that: The thread guide (7) is provided with a thread guide eye (70) having a wear-resistant surface, wherein a hollow insert (75) made of a wear-resistant ceramic material is mounted to the thread guide (7) and serves as the thread guide eye (70).

11. The device for forming a leno weave according to claim 10, characterized in that: The thread guide (7) is L-shaped, having a first end provided with the yarn guide eye (70) and a second end provided with the first section (72), wherein the first end and the second end are arranged at an angle to each other.

12. The device for forming a leno weave according to claim 11, characterized in that: An angle between the first end and the second end is greater than 90°.

13. The device for forming a leno weave according to claim 1, 2 or 3, characterized in that: At least one thread detector (20, 21) is provided for detecting the absence and / or presence of a leno thread (2, 3) to be guided by the thread guide (7).

14. The device for forming a leno weave according to claim 1, 2 or 3, characterized in that: The pulley (9) is a drive pulley which is drivingly coupled to a motor, wherein the motor is synchronized to the weaving machine.

15. The device for forming a leno weave according to claim 14, characterized in that: The motor is an electric motor.

16. The device for forming a leno weave according to claim 1, 2 or 3, characterized in that: A sensor (17) fixed in place is provided, the sensor (17) being adapted to give a signal each time the thread guide (7) passes the sensor (17).

17. The device for forming a leno weave according to claim 16, characterized in that: The sensor (17) is a proximity switch or a Hall sensor, and the wire guide (7) is at least partially made of a magnetizable material.

18. The device for forming a leno weave according to claim 17, characterized in that: The wire guide (7) is at least partially made of steel.

19. The device for forming a leno weave according to claim 1, 2 or 3, characterized in that: A pair of wire guides (7) are mounted to the annular support element (6), wherein the wire guides (7) of the pair of wire guides are distributed along the annular support element (6).

20. A weaving machine comprising the device (1) for forming a leno weave according to any one of claims 1 to 19.

21. A method for manufacturing a device (1) for forming a leno weave according to any one of claims 1 to 19, the device (1) comprising an annular support element (6) and a thread guide (7) mounted to the annular support element (6), characterized in that: The thread guide (7) is fixed to the annular support element (6) by means of a clamp having two sections (72, 73) such that the two sections (72, 73) of the clamp (71) of the thread guide (7) extend at opposite sides of the annular support element (6).

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