Weft insertion device for a weaving machine

Abstract

The invention relates to a weft insertion device (14) for inserting a weft yarn (15) into a shed (13) or a reed channel (16) of a weaving machine (10). The weft insertion device (14) is designed to convey a plurality of different weft yarns (15) out of one yarn store (18) each and to insert same into the shed (13) or the reed channel (16) from a weft channel (27) of a weft insertion tube (26) by means of compressed air. The different weft yarns (15) each have a yarn supply tube (39) with a yarn supply channel (40), each yarn supply channel (40) leading into the weft channel (27) at a supply opening (41). The same weft channel (27) is therefore provided for all of the weft yarns (15) to be inserted. By means of compressed air which is introduced into the weft channel and can be designated primary air (P), an end portion (42) of the weft yarn (15) located within the air flow of the primary air (P) can be conveyed out of the weft channel (27) and inserted into the shed or the reed channel (16). The weft channel (27) which is provided for all of the different weft yarns (15) can be optimally aligned in the weft direction (S) with the reed channel (16) or the shed (13).

Description

German Institute for Textile and Fiber Research Denkendorf 18 September 2023 DITF P037 WO prrn Körschtalstraße 26 Keyword: 73770 Denkendorf Air-jet weaving Weft insertion device for a weaving machine

[0001] The invention relates to a weft insertion device for a weaving machine. The weft insertion device is designed to insert a weft thread into a reed channel in a weft direction.

[0002] The weft insertion device can optionally also include one or more relay nozzles and / or a stretching nozzle. The weft thread inserted by the weft insertion device is slowed down by air resistance and remains unstretched. The thread is transported further by the air flow through several relay nozzles positioned on the reed channel until it reaches the opposite side of the fabric, where it can be held stretched by the stretching nozzle until the reed beat-up occurs.

[0003] Weaving machines are known in which the weft thread is inserted during weaving with the aid of compressed air by a corresponding weft insertion device. This method of inserting a weft thread into a reed channel or open shed is also known as air-jet weaving.

[0004] Weaving machines may require the use of several different weft threads, for example, weft threads of different colors and / or weft threads made of different materials. In air-jet weaving, For this purpose, weft insertion devices are used which have a nozzle for each weft thread used in weaving, by means of which the respective weft thread is injected into the reed channel with the aid of air pressure. A disadvantage has proven to be that only one of the available air nozzles - also referred to as the main nozzle - can be optimally aligned with the reed channel. Since the reed channel has a relatively small channel cross-section, the air nozzles cannot be arranged parallel to one another in the extension of the reed channel. It is therefore necessary to arrange several or all of the air nozzles at an angle relative to the direction of extension of the reed channel. Depending on the number of air nozzles used, inclinations of up to around 7° relative to the desired weft direction - i.e. the direction of extension of the reed channel - can occur.

[0005] In the weaving machines known to date, which are equipped for air-jet weaving, the energy consumption of the weaving machine for operating the weft insertion device amounts to approximately 30% of the total energy consumption. The generation of the compressed air required for weft insertion is therefore very energy-intensive. If the air nozzles for weft insertion are inclined relative to the reed channel, this adversely affects the efficiency of conveying the weft thread using compressed air, increasing the compressed air requirement (pressure and duration of the compressed air discharge). Furthermore, there is a risk that an air nozzle aligned at an angle to the reed channel will cause the inserted weft thread to strike the reed and thus not be inserted completely or correctly into the shed. The probability of weft insertion errors increases.

[0006] To avoid this problem, Picanol nv offers a weft insertion device called "PosiJet" that uses a movable air jet assembly. Each air jet of the air jet assembly is moved into a desired position relative to the reed channel before weft insertion to optimize the weft insertion direction of the weft thread into the reed channel. However, this solution requires a very complex design of the air jet assembly to be able to move it into the desired position sufficiently quickly. The entire mass of the air jet assembly must be moved.

[0007] Based on the known prior art, it can be considered the object of the present invention to provide a more energy-efficient weft insertion device that enables high weaving speeds while at the same time having a low error rate in the weft thread insertion.

[0008] This object is achieved by a weft insertion device having the features of patent claim 1.

[0009] The weft insertion device according to the invention is designed to insert a weft thread in a weft direction into an open shed or reed channel of a weaving machine's reed. The weft insertion device operates with compressed air support. The weft thread to be inserted is inserted into the open shed or reed channel by compressed air from a weft insertion tube. Optionally, additional air discharge nozzles and / or suction devices can be provided along the reed channel and / or on a side of the reed channel opposite in the weft direction in order to To support or improve weft thread guidance along the reed channel.

[0010] The weft insertion tube defines a weft channel. In particular, there is a single weft insertion tube with a single weft channel. The weft insertion tube can be optimally aligned relative to the reed channel. A longitudinal center axis of the weft channel defines the weft direction in which the weft is to be inserted into the reed channel or the open shed. The longitudinal center axis of the weft channel can be aligned parallel or slightly inclined to the weft direction, which depends in particular on the shape of the weft channel. The reed channel extends in particular as an extension of the longitudinal center axis of the weft channel.

[0011] The weft insertion device also has at least two thread feed tubes. Each thread feed tube defines a thread feed channel. Each thread feed channel opens into the weft channel of the weft insertion tube at a feed opening. An individual weft thread can be fed to the weft channel via each thread feed channel. Depending on the number of thread feed tubes or thread feed channels, at least two, but also more than two, for example four or eight, different weft threads can be fed. This makes it possible to use the weft insertion device to use several different weft threads in weaving, which differ, for example, in terms of color and / or titer and / or material. In particular, exactly one weft thread is fed through each thread feed channel.

[0012] For the arrangement of the thread feed pipes or the There are various options for thread feed channels. The feed openings can be arranged parallel to the longitudinal center axis of the firing channel and / or offset in the circumferential direction around the longitudinal center axis of the firing channel or adjacent to one another. Depending on the selected arrangement, it is possible, for example, in one embodiment for all thread feed tubes and / or thread feed channels to be aligned parallel to a common plane. Alternatively, the thread feed tubes and / or thread feed channels can also be arranged, for example, in a common virtual truncated cone surface or in several virtual truncated cone surfaces. The choice of arrangement depends, for example, on the number of desired or required thread feed channels.

[0013] The weft insertion device also has an air duct tube. The air duct tube defines an air duct. In one embodiment, a single air duct tube with a single air duct is provided. Alternatively, multiple air ducts and / or multiple air duct tubes may be provided.

[0014] The at least one air duct is designed to direct compressed air into the weft channel and, for this purpose, opens into the weft channel at an air duct opening. The air duct opening is located behind the feed openings of the thread feed channels in the weft direction. Compressed air can be introduced into the weft channel via the air duct opening in the weft direction in order to convey an end section of a weft thread present in the weft channel out of the weft channel by the air flow and into the reed channel or the open shed.

[0015] The inventive design of the weft insertion device enables energy-efficient air jet weaving. Because the air duct opening is positioned behind the feed openings in the weft direction, little or no compressed air escapes from the air duct via one of the feed openings into the respective thread feed duct. The compressed air used to convey the weft thread from the weft duct flows completely, or at least essentially completely, in the weft direction through the weft duct, i.e., toward the reed duct, exits at the opening of the weft duct, and at least partially enters the reed duct. The weft duct can be optimally configured relative to the reed duct.

[0016] It has been shown that, compared to previous weft insertion devices with air nozzles that are not optimally aligned in terms of flow, significant energy savings of 2-3% or up to 10% and more can be achieved. Movable air nozzles or weft insertion tubes for one or more weft threads are not required. Furthermore, the risk of weft insertion errors is minimized by the inserted weft thread beating up against the reed. The structural design of the weft insertion device according to the invention is significantly simpler than that of movable air nozzles. Several different weft threads can be inserted in quick succession. Furthermore, it is also fundamentally possible to insert two or more weft threads simultaneously through the common weft channel into the reed channel or the open shed.

[0017] It is advantageous if the weft insertion process direction also has at least two thread conveying units. Each thread feed channel is assigned a thread conveying unit. Each thread conveying unit is designed to convey an end section of the assigned weft thread into the weft channel. In one embodiment, the conveying of the end section of the weft thread into the weft channel can be carried out by means of conveying air or at least assisted by conveying air. For this purpose, each thread conveying unit can have a conveying air connection through which conveying air can be fed into the assigned thread feed channel. The conveying air flow flows through the relevant thread feed channel and the feed opening into the weft channel and from there further along the weft channel in the weft direction, whereby the end section of the weft thread can be arranged at least partially in the weft direction behind the air channel opening.When air subsequently escapes through the air duct opening, the relevant weft thread is transported further in the weft direction.

[0018] In addition to or as an alternative to conveying a weft thread using conveying air, other thread conveying units can also be used, which, for example, have mechanical conveying means or work with negative pressure.

[0019] As already explained, it is also possible to position an end section of a weft thread in the weft channel via several thread feed channels and insert two or more weft threads simultaneously. Consecutive weft thread insertions can be performed at a high repetition rate or frequency, for example, 1,000 weft insertions or more per minute.

[0020] A particularly advantageous embodiment of the weft insertion device is one in which a thread retraction unit is assigned to each thread feed channel. Each thread retraction unit is designed to move the end section of the assigned weft thread extending through the thread feed channel in a retraction direction in the weft channel, counter to the weft direction, and in particular to move it in the retraction direction behind the air channel opening. The thread retraction unit can remove an end section of a weft thread that was used during the last weft insertion from the area between the air channel opening and the opening of the weft channel, so that this area is free for the next weft thread to be inserted. Such retraction is only necessary if a different weft thread is to be used for the next weft insertion.

[0021] The thread retraction unit can have at least one thread deflection element for retracting the end section of the associated weft thread, which can be moved between a first position and a second position. The thread deflection element can deflect an associated section of the weft thread more strongly in the second position than in the first position, compared to a fully stretched position of the weft thread. This greater deflection lengthens the path or length of a section of the weft thread that extends obliquely or at right angles to the direction of travel of the weft thread or the oblique position of the weft thread, whereby the end section of the relevant weft thread located in the weft channel can be moved in the retraction direction opposite to the weft direction.

[0022] Depending on the available travel or stroke of the at least one thread deflection element between the first position and the second position, it may be necessary to provide several such thread deflection elements in each thread retraction unit in order to achieve a sufficient travel length for retracting the end portion of the weft thread. The thread deflection elements can then, for example, be arranged next to one another along the extension of the associated weft thread.

[0023] In one embodiment, the at least one thread deflection element can assume the first position as the starting position. It can be forced into the starting position or the first position, for example, by the force of weight or a spring-elastic body. Alternatively, the at least one thread deflection element can also be held in the first position and / or the second position and / or moved between the two positions by an electrically or piezoelectrically generated force.

[0024] For movement between the first position and the second position or vice versa and / or for holding in the first position and / or the second position, a controllable drive can be assigned to each thread deflection element. In particular, an individually controllable separate drive can be assigned to each thread deflection element. The drive can be a linear drive, for example. The movement can be generated by a piezoelectric force of a piezoelectric drive or, for example, by a moving coil drive. With a moving coil drive, an armature moves inside a coil and is moved electromagnetically. Other electromagnetic drives can also be used.

[0025] It is also possible to group at least several thread deflection elements and to assign a common drive to this group.

[0026] In order to be able to sever a weft thread inserted into an open shed or into the reed channel, the weft insertion device can have a controllable separating device. The separating device can be arranged behind the opening of the weft channel in the weft direction, which simplifies the structural design. Alternatively, the separating device can also be arranged in the area between the feed openings and the opening of the weft channel, for example, in or on the weft insertion tube. The separating device can have mechanical separating means (e.g., a blade or cutting edge) or contactless separating means, such as a laser, for separating the weft thread.

[0027] In an advantageous embodiment of the weft insertion device, at least one air nozzle can be provided in the air flow path, particularly within the air duct of the air duct tube, to increase the air flow velocity in the weft direction. The air nozzle can be designed, for example, as a Laval nozzle. This allows the air flow velocity to be increased to supersonic speed.

[0028] The air duct pipe can have a single geometry or cross-sectional shape (e.g. rectangular, square, circular, etc.) along its length or it can at least one geometric change and thus different cross-sectional shapes. This at least one geometric change allows even more effective air flow conditions to be achieved, for example, to account for boundary layer processes, turbulence, separation, or similar flow effects. This applies not only to the air duct tubes, but also to the weft channel tube and / or the yarn feed tube. Improved yarn transport can be achieved, particularly when using multiple yarns with different properties (e.g., transport and yarn properties). This allows the yarn insertion and yarn retention to be optimized and adjusted.

[0029] Advantageous embodiments of the invention emerge from the dependent claims, the drawings, and the description. Preferred embodiments of the invention are explained in detail below with reference to the accompanying drawings. In the drawings:

[0030] Figure 1 is a highly schematic diagram of a part of a weaving machine with a weft insertion device,

[0031] Figure 2 is a highly schematic, block diagram-like representation of an embodiment of a weft insertion device according to the present invention,

[0032] Figures 3 to 5 show the weft insertion device from Figure 3 in different stages during the insertion of a weft thread or during weaving,

[0033] Figure 6 shows a highly schematic, block-switched image-like representation of a further embodiment of a weft insertion device according to the invention,

[0034] Figure 7 shows an embodiment of a weft insertion device according to the invention in a schematic representation looking against a weft direction,

[0035] Figure 8 is a highly schematic, block diagram-like representation of another embodiment of a weft insertion device,

[0036] Figure 9 is a highly schematic, block diagram-like representation of an embodiment of a thread retraction unit for any embodiment of a weft insertion device, wherein thread deflection elements are in a first position,

[0037] Figure 10 shows the thread retraction unit from Figure 9, with the thread deflection elements in a second position,

[0038] Figure 11 is a schematic diagram of a drive for a thread deflection element from Figure 9 or 10 with an electromagnetic drive,

[0039] Figure 12 is a schematic diagram of a piezoelectric drive for a thread deflection element from Figure 9 or 10,

[0040] Figure 13 shows an embodiment of an air duct tube of any embodiment of the weft insertion device comprising an air nozzle, and

[0041] Figures 14 and 15 each show a highly schematic, perspective representation of a further embodiment of a weft insertion device according to the invention.

[0042] Figure 1 shows part of a weaving machine 10 in a highly schematic, simplified schematic diagram. The weaving machine 10 has several heald shafts 11, which serve to guide warp threads 12. By positioning the heald shafts 11, a shed 13 can be opened.

[0043] The weaving machine 10 has a weft insertion device 14 for inserting a weft thread 15 into the shed 13. The weft thread 15 is inserted or conveyed in a weft direction S by the weft insertion device 14, which in Figure 1 is directed toward the viewer at right angles to the plane of the drawing. The weft thread 15 is inserted into the shed 13, for example, along a reed channel 16 of a reed 17.

[0044] Inserting a weft thread 15 means inserting a length of the weft thread 15 along the entire width of the shed 13. After insertion of the weft thread 15, it is usually still connected to a thread supply 18 from which the weft thread 15 was taken. The weft insertion device 14 can convey the weft thread 15 using compressed air. This process is also referred to as air-jet weaving.

[0045] By means of a separating device 19 (Figures 2-6), the weft thread 15 can be separated from the thread supply 18. At the same time, before or thereafter, the inserted weft thread 15 is beaten onto a fabric edge 20 of an already produced fabric 21 by means of the reed 17. The already produced fabric 21 can be drawn off by means of a draw-off device 22 and, for example, rolled up onto a roll.

[0046] As shown schematically in Figure 1, when weaving with the weaving machine 10, several different weft threads 15 can be used from a respective thread supply 18 and inserted into the shed 13 or the reed channel 16 by means of the weft insertion device 14.

[0047] A weft insertion device 14 configured for air-jet weaving and inserting the weft threads 15 into the shed 13 using compressed air is shown in Figure 2 in the form of a block diagram. The weft insertion device 14 has a weft insertion tube 26 that defines a weft channel 27. The weft channel 27 extends along a longitudinal central axis A. On its side facing the reed 17 or the reed channel 16, the weft channel 27 has a weft channel opening 28. A weft thread 15 to be inserted can be conveyed or accelerated out of the weft channel opening 28 and inserted into the shed or the reed channel 16.

[0048] The weft insertion device 14 also has an air duct tube 29, which in the embodiment shown in Figure 2 extends parallel to the longitudinal center axis A or coaxially to the longitudinal center axis A. The air duct tube 29 defines an air duct 30, which opens into the weft channel 27 at an air duct opening 31. The air duct opening 31 is arranged in front of the weft channel opening 28, viewed in the weft direction S. A longitudinal section of the weft channel 27 in the weft direction S between the air channel opening 31 and the weft channel opening 28 can be referred to as the main flow section 32. Compressed air from a pressure source 33 upstream of the air channel opening 31 can be supplied to the air channel 30, this compressed air serving to insert the weft thread 15 and can be referred to as primary air P to distinguish it from other air flows. A first valve 35, controllable by means of a control device, can be arranged between the pressure source 33 and the air channel 30. By means of the first valve 35, the control device 34 can control the supply of primary air P to the air channel 30, in particular interrupt it or release it.

[0049] The weft insertion device 14 also has a plurality of thread feed tubes 39, two of which are illustrated in Figure 2 merely by way of example. Each thread feed tube defines a thread feed channel 40. The thread feed channel 40 opens into the weft channel 27 at a feed opening 41. A weft thread 15 can be guided through each thread feed channel 40 via the feed opening 41 into the weft channel 27, so that the loose or free end of the weft thread 15 is located within the weft channel 27, as schematically illustrated in Figure 2. In an initial state of the weft insertion device 14, the loose ends of the weft threads 15 are preferably arranged outside the main flow section 32 and are thus located in front of the air channel opening 31 in the weft direction S.

[0050] In order to connect a loose end or free end and an adjoining end section 42 of an associated In order to convey the weft thread 15 into the main flow section 32, a thread conveying unit 43 is assigned to each thread feed channel 40. In the exemplary embodiment, the thread conveying unit 43 conveys the assigned weft thread 15 into the relevant thread feed channel 40 by supplying conveying air F. For this purpose, each thread feed channel 40 or each thread feed pipe 39 has a conveying air connection 44, which is a component of the respective thread conveying unit 43. The conveying air F flowing in the thread feed channel 40 can entrain the section of the weft thread 15 arranged there and convey it along the thread feed channel 40 via the relevant feed opening 41 into the weft channel 27.The length of the weft thread 15 arranged within the weft channel 27 (as viewed from the loose or free end of the weft thread 15) thereby increases, so that the loose or free end of the respective weft thread 15 can be positioned in the region of the main flow section 32 of the weft channel 27. The introduced conveying air F can escape from the weft channel opening 28.

[0051] Each thread conveying unit 43 can be individually controlled by the control device 34 in order to convey the respectively assigned weft thread 15 individually and independently of the at least one other weft thread 15 into the weft channel 27. In the exemplary embodiment, the conveying air F can be controlled for this purpose, in particular switched on or off. For this purpose, for example, each conveying air connection 44 can be supplied with conveying air F from the pressure source 33 or fluidically separated from the pressure source 33 via a secondary valve 45 controllable by the control device 34.

[0052] Figures 14 and 15 each show schematically a further embodiment of a weft insertion device 14 is illustrated. In this embodiment, the air duct tubes 29 are arranged distributed in the circumferential direction around the longitudinal center axis A. Analogously, the thread feed tubes 39 are also arranged distributed in the circumferential direction around the longitudinal center axis A. Deviating from the illustration, more or fewer air duct tubes 29 and / or thread feed tubes 39 can also be present.

[0053] In the exemplary embodiments according to Figures 14 and 15, the pressure source 33 comprises a pressure generating unit 33a (e.g., a pump) and one or more pressure accumulators 33b. The pressure generating unit 33a and the pressure accumulator 33b are fluidically connected, optionally via one or more valves. The pressure generating unit 33a can also be a compressed air system in a building.

[0054] In the embodiment according to Figure 14, a common pressure accumulator 33b is assigned to the air duct pipes 29, to which the air duct pipes 29 are fluidically connected. The pressure accumulator 33b is ring-shaped here and coaxially surrounds the longitudinal center axis A.

[0055] In the embodiment according to Figure 15, each air duct pipe 29 is assigned a separate pressure accumulator 33b, to which an air duct pipe 29 is fluidically connected. Analogous to the embodiment according to Figure 14, the pressure accumulators 33b are fluidically connected to a pressure generation unit 33a. The pressure accumulators 33b are shown as cylindrical only for illustrative purposes. Analogous to the embodiment according to Figure 14, they can also be arranged in a ring around the longitudinal center axis A. The design The configuration examples of Figures 14 and 15 can thus be combined with one another. In a further modification, several pressure accumulators 33b can be present, wherein more than one air duct pipe 29 can be fluidically connected to each pressure accumulator 33b.

[0056] In the embodiments according to Figures 14 and 15, the arrangement of the air duct tubes 29 and / or the thread feed tubes 39 can correspond to any of the embodiments described above, as explained in particular in connection with Figures 2-8.

[0057] In Figures 14 and 15, the valves 35, 45 are not illustrated for the sake of clarity and can be present in the fluid connection to the respective pressure accumulator 33b and / or in the fluid connection between the at least one pressure accumulator 33b and the respectively connected air duct pipe 29.

[0058] If multiple pressure accumulators 33b are present, in particular one for each air duct pipe 29, the pressure accumulators 33b can be made very small and adapted to the available installation space. Such pressure accumulators 33b can be advantageously manufactured using a winding and spooling technique.

[0059] If several air duct pipes 29 are connected to a pressure accumulator 33b, the pressure accumulator 33b can optionally be pressurized with different bridges, depending on which connected air duct pipe 29 is to be pressurized with the stored compressed air next. Similarly, several pressure accumulators 33b can be pressurized with different pressures. For fluid connection between the pressure generating unit 33a and the pressure accumulators 33b, appropriate devices, for example valves or the like, can be provided.

[0060] In general, in all embodiments of the weft insertion device 14, the geometric configuration of the weft channel 27 and / or of the at least one air duct tube 29 and / or of the thread feed tubes 39 can be designed as desired. The cross-sectional geometry can change in the extension direction of the respective tube or it can remain constant. For example, the cross-sectional shape can always be polygonal or always circular. However, it can also optionally be changed from a polygonal shape to a circular shape, so that a geometric transition occurs. In general, the geometry and the number of optionally present geometric transitions can be selected as desired and adapted to the respective application. The geometric design allows the thread feed and flow conditions to be optimized and designed efficiently.

[0061] In order to move an end section 42 of a weft thread 15 located in the main flow section 32 in a retraction direction R opposite to the weft direction S from the main flow section 32, the weft insertion device 14 in the embodiment illustrated here has at least one thread retraction unit 50. Preferably, a separate thread retraction unit 50 is provided for each weft thread 15. The at least one thread retraction unit 50 can be controlled by the control device 34 to retract the associated weft thread 15.

[0062] An exemplary embodiment of a thread retraction unit 50 is illustrated in Figures 9 and 10 in a highly schematic manner. The thread retraction unit 50 can have a thread deflection element 51 and preferably a plurality of thread deflection elements 51, which can be moved obliquely or at right angles to a thread extension direction E between a first position I (Figure 9) and a second position II. The thread extension direction E defines a direction that corresponds to a stretched position of the section of the weft thread 15 that extends in the region of the thread retraction unit 50.

[0063] For movement between the first position I and the second position II, at least one drive 52 is provided for the thread deflection element(s) 51. It is possible to provide an individually controllable drive 52 for two or more than two or all of the thread deflection elements 51 present, so that the thread deflection elements 51, which are motion-coupled by different drives 52, can be moved or positioned independently of one another.

[0064] In the embodiment of the thread retraction unit 50 illustrated in Figures 9 and 10, one of the thread deflection elements 51 serves as a clamping element 51a, which is designed to release the associated weft thread 15 in the first position I and to clamp it in the second position II. For this purpose, a stop surface 53 is assigned to the clamping element 51a, which is spaced apart from the clamping element 51a in the first position I. In the second position II, the weft thread 15 is clamped between the clamping element 51a and the stop surface 53 are clamped.

[0065] The clamping element 51a is arranged on the side of the thread retraction unit 50 that is further away from the loose end or end section 42 of the weft thread 15. The optional additional thread deflection elements 51, which are present in the exemplary embodiment, are arranged adjacent to the thread deflection element 51 forming the clamping element 51a in the thread extension direction E. As schematically illustrated in Figures 9 and 10, the thread deflection elements 51 are located alternately on opposite sides of the weft thread 15. In the thread extension direction E, the thread deflection elements 51 are arranged offset. They can therefore be positioned in the second position II, so to speak, overlapping in a toothed manner.

[0066] The thread retraction unit 50 according to the embodiment of Figures 9 and 10 operates in principle as follows:

[0067] If an end section 42 of a weft thread 15 is to be retracted, the clamping element 51a is first moved into the second position II. This prevents the application of force to the weft thread 15 from leading to the supply of the weft thread 15 from the thread supply 18. Subsequently, or alternatively at least partially simultaneously, the movement of the further thread deflection elements 51 from the first position I (Figure 9) towards the second position II (Figure 10) is triggered or carried out. The section of the weft thread 15 running in the area of ​​the thread retraction unit 50 is thereby released from its Thread extension direction E is deflected more strongly compared to the first position I, whereby the end section 42 or the loose end of the weft thread 15 is moved in the retraction direction R in the weft channel 27 and, for example, is pulled out of the main flow section 32. The path that each thread deflection element 51 travels between the first position I and the second position II, as well as the number of thread deflection elements 51 used, can be used to adjust the required retraction path of the loose end of the weft thread 15.

[0068] A linear drive 54, for example an electromagnetic drive 55 (Figure 11) or a piezoelectric drive 56 (Figure 12), can be used as the drive for the thread deflection element 51 or the thread deflection elements 51. The electromagnetic drive 55 can be, for example, a moving coil drive 57. The moving coil drive 57 has a coil 58 in which an armature 59 is movably mounted. The armature 59 is motion-coupled to the thread deflection element 51, for example, fixedly connected. A current i can be caused to flow through the coil 58 via the control device 34, so that a magnetic field is formed, which in turn moves the armature 59. Depending on the flow direction of the current i, the movement of the armature 59 can optionally also be caused electromagnetically in opposite directions, for example from the first position I to the second position II, as well as vice versa.

[0069] The piezoelectric drive 56 shown schematically in Figure 12 has a piezo factor 60 to which the control device 34 can apply a voltage u in order to adjust the piezo factor 60 based on the piezoelectric effect to deform in the direction in which the thread deflection element 51, which is motion-coupled to the piezoelectric factor 60, is to be moved. By switching the voltage u on and off, a movement of the thread deflection element 51 between the two positions I, II can thus be caused.

[0070] With the aid of the drives 54 shown as examples in Figures 11 and 12, very high frequencies of movement of the thread deflection element 51 can be achieved. The retraction of the weft thread in the retraction direction R can therefore be carried out sufficiently quickly even for high-speed weaving machines.

[0071] The weft insertion device 14 shown in Figure 2 also has a separating device 64 controllable by the control device 34. The separating device 64 is designed to sever a weft thread 15 inserted into the shed 13 or the reed channel 16 and thus separate it from the thread supply 18. After the weft thread 15 has been severed, it has a loose end immediately adjacent to the separating device 64, to which the end section 42 is connected.

[0072] The separating device 64 is schematically illustrated in Figures 2-6. It can have a mechanical blade or cutting edge for severing the weft thread 15. Alternatively or additionally, the separating device 64 can also use a laser beam to sever the weft thread 15, as is schematically illustrated in Figure 8. The separating device 64 can be arranged behind the weft channel opening 28 in the weft direction S, as is the case in the embodiments according to Figures 2-6. Additionally or alternatively the separating device 64 can also be arranged at any other location, for example in the area of ​​the firing channel 27 in the firing direction S at any location, for example behind the air channel mouth 31 (Figure 8).

[0073] The components of the weft insertion device 14 that can be controlled by the control device 34 are indicated in the drawing by dashed arrows. The control device 34 uses, for example, electrical and / or electronic signals to control these components. The control device 34 can have a microprocessor to execute control commands and control the weft insertion device so that a desired process sequence is achieved for the weft insertion. The process or process sequence is explained below based on Figures 2-5.

[0074] Figure 2 illustrates the initial position or situation. The weft threads 15 are arranged with their loose ends and the adjoining end sections 42 outside the main flow section 32, with the loose ends located in the weft direction S in front of the air duct opening 31 in the weft channel 27.

[0075] In order to insert a weft thread from the weft channel 27 into the shed 13 or the reed channel 16, the thread conveying unit 43 assigned to this weft thread 15 is first activated. For this purpose, conveying air F is guided into the respective thread feed channel 40, in the exemplary embodiment into the thread feed channel 40 shown at the bottom in Figure 3. The conveying air F flows through the thread feed channel 40 into the weft channel 27 and transports the loose end into the main flow section 32, i.e. behind the air duct opening 31 as seen in the weft direction S. As soon as the loose end or a sufficiently long end section 42 of the weft thread 15 is located in the main flow section 32, the control device 34 can guide primary air P into the air duct 30, which exits into the main flow section 32 and moves the end section 42 of the weft thread 15 present there in the weft direction S. As a result, the loose end of the weft thread 15 is drawn out of the weft channel 27 and further into the shed 13 or the reed channel 16. This situation is illustrated schematically in Figure 3.

[0076] After the weft thread 15 has passed through the shed 13 or the reed channel 16 and the loose end is located on the side of the fabric 21 opposite the weft insertion device 14, the weft thread 15 is separated from the respective thread supply 18 by actuating the separating device 64 (Figure 4). This creates a new loose end of the weft thread 15, which is connected to the thread supply 18. Depending on the position of the separating device 64, the loose end and / or the adjoining end section 42 can be located in the main flow section 32 of the weft channel 27, as is the case in the embodiment shown in Figures 2-5. In order to enable the trouble-free insertion of another weft thread 15, the loose end or the end section 42 of the last inserted weft thread 15 is therefore withdrawn from the main flow section 32 in the retraction direction R opposite to the weft direction S.For this purpose, the thread retraction unit 50 assigned to the weft thread 15 is actuated, as shown schematically in Figure 5. At the end of the retraction movement, the end section 42 is again arranged outside the main flow section 32, so that the initial situation shown schematically in Figure 2 is again obtained.

[0077] In a modified embodiment, the at least one thread retraction unit 50 can be dispensed with if the separating device 64 is arranged in the weft direction S at a position upstream of the main flow section 32. Then, the loose end and the adjoining end section 42 of the last inserted weft thread are already arranged outside the main flow section 32 immediately after severing. The rear end of the weft thread 15 inserted into the shed 13, which is assigned to the weft insertion device 14 after severing the inserted weft thread 15, can - if necessary - be completely removed from the weft channel 27 by an air flow, for example by the primary air P, another air flow, or by another suitable means.

[0078] A further option is to cut the weft thread 15 at several points after it has been inserted into the shed 13, for example at a point between the fabric 21 and the weft channel opening 28 and at another point in the weft direction S in front of the main flow section 32. A weft thread remnant that remains between these two cutting points can then also be removed from the weft channel 27 by an air flow or in another way.

[0079] As already explained, the number of used weft threads and thus the number of thread feed tubes 39 or thread feed channels 40 vary. The representations in the drawing are merely examples. While Figures 2-5 show two weft threads 15 and two thread feed channels 40, Figure 6 shows an example of four different, insertable weft threads 15 and four thread feed channels 40. In general, the number of thread feed channels 40 used is arbitrary. Depending on the number of thread feed channels 40 required, these can have feed openings arranged parallel to the longitudinal center axis A and / or offset in a circumferential direction around the longitudinal center axis A. Merely as an example, Figure 7 shows an embodiment of a weft insertion device 14 in which eight thread feed tubes 39, each with a thread feed channel 40, are offset in the circumferential direction U and, for example, are arranged in a regularly distributed manner.

[0080] In a further embodiment, which is illustrated schematically in Figure 8, instead of a central air duct pipe 29 or a central air duct 30, the supply of primary air P can take place via several separate air duct pipes 29 or air ducts 30. The thread supply ducts 40 can, for example, open laterally into the weft channel 27 behind the supply openings 41 in the weft direction S, as shown by way of example in Figure 8.

[0081] In order to achieve a sufficient flow velocity of the primary air P in the firing channel 27, an air nozzle 65 can be arranged or formed in the flow path of the primary air P. For example, the air nozzle can be arranged in the air channel 30, as shown in Figure 13. The air nozzle 65 can be designed as a Laval nozzle. The primary air P can, after flowing through the air nozzle 65, accelerated to supersonic speed.

[0082] As an alternative to the arrangement or design of the air nozzle 65 in the air channel 30, the air nozzle 65 can be arranged or designed in the flow path of the primary air P in the firing channel 27, as shown by way of example in dashed lines in Figure 8.

[0083] The invention relates to a weft insertion device 14 for inserting a weft thread 15 into a shed 13 or a reed channel 16 of a weaving machine 10. The weft insertion device 14 is designed to convey a plurality of different weft threads 15, each from a thread supply 18, and to insert them into the shed 13 or the reed channel 16 by means of compressed air from a weft channel 27 of a weft insertion tube 26. A thread feed tube 39 with a thread feed channel 40 is provided for each of the different weft threads 15, wherein each thread feed channel 40 opens into the weft channel 27 at a feed opening 41. The same weft channel 27 is thus provided for all weft threads 15 to be inserted. By means of compressed air introduced into the weft channel, which can be referred to as primary air P, an end section 42 of the weft thread 15, which is located within the air flow of the primary air P, can be conveyed out of the weft channel 27 and into the shed orthe reed channel 16. The weft channel 27, which is provided for all the different weft threads 15, can be optimally aligned in the weft direction S onto the reed channel 16 or the shed 13. List of reference symbols: 10 Weaving machine 11 Heald frame 12 Warp thread 13 Weaving shed 14 Weft insertion device 15 Weft thread 16 Reed channel 17 Reed 18 Thread supply 19 Separating device 20 Fabric edge 21 Fabric 22 Take-off device 26 Weft insertion tube 27 Weft channel 28 Weft channel opening 29 Air channel tube 30 Air channel 31 Air channel opening 32 Main flow section 33 Pressure source 33a Pressure generation unit 33b Pressure accumulator 34 Control device 35 Primary valve 39 Thread feed tube 40 Thread feed channel 41 Feed opening 42 End section 43 Yarn feed unit 44 Conveying air connection 45 Secondary valve 50 Yarn retraction unit 51 Yarn deflection element 51a Clamping element 52 Drive 53 Stop surface 54 Linear drive 55 Electromagnetic drive 56 Piezoelectric drive 57 Voice coil drive 58 Coil 59 Armature 60 Piezo factor 64 Separating device 65 Air nozzle A Longitudinal center axis E Yarn extension direction F Conveying air i Current P Primary air S Weft direction R Retraction direction u Tension I First position II Second position

Claims

Claims:

1. Weft insertion device (14) for a weaving machine (10), which is designed to insert a weft thread (15) in a weft direction (S) into a reed channel (16), comprising: - a weft insertion tube (26) which delimits a weft channel (27), - at least two thread feed tubes (39), each delimiting a thread feed channel (40), wherein each thread feed channel (40) opens into the weft channel (27) at a feed opening (41), and wherein each thread feed channel (40) is designed to feed a weft thread (15) to the weft channel (27), - at least one air duct tube (29), each delimiting an air duct (30), wherein each air duct (30) opens into the weft channel (27) at an air duct opening (31), wherein the air duct opening (31) in the weft direction (S) behind all existing feed openings (41). 2.Weft insertion device according to claim 1, wherein only a single weft insertion tube (26) with a single weft channel (27) is present.

3. Weft insertion device according to claim 1 or 2, further comprising at least two thread conveying units (43), wherein each thread feed channel (40) is assigned one of the thread conveying units (43) which is configured to convey an end portion (42) of the weft thread (15) into the weft channel (27).

4. Weft insertion device according to claim 3, wherein each thread conveying unit (43) is configured to convey the end section (42) of the weft thread (15) into the weft channel (27) so far that it is arranged behind the at least one air channel opening (31) in the weft direction (S).

5. Weft insertion device according to claim 3 or 4, wherein each thread conveying unit (43) has a conveying air connection (44) and is configured to convey the end section (42) of the weft thread (15) by means of conveying air (F), which can be guided through the conveying air connection (44) into the thread feed channel (40).

6. Weft insertion device according to one of the preceding claims, wherein the at least one air channel pipe (39) has an air nozzle (65).

7. Weft insertion device according to one of the preceding claims, wherein the weft insertion tube (27) has an air nozzle (65) behind the at least one air duct opening (31) in the weft direction (S).Weft insertion device according to one of the preceding claims, which is configured to insert a plurality of weft threads (15) simultaneously into the reed channel (16).

9. Weft insertion device according to one of the preceding claims, which is configured to insert a plurality of weft threads (15) successively into the reed channel (16) at a frequency of at least 200 wefts per minute or at least 500 wefts per minute or at least 1000 wefts per minute.

10. Weft insertion device according to one of the preceding claims, further comprising at least two thread retraction units (50), wherein each thread feed channel (40) is assigned one of the thread retraction units (50), which is configured to retract an end portion (42) of the weft thread (15) counter to the weft direction (S) in a retraction direction (R).

11. Weft insertion device according to claim 10, wherein each thread retraction unit (50) has at least one thread deflection element (51) which is movably mounted between a first position (I) and a second position (II), wherein the at least one thread deflection element (51) deflects an associated portion of the weft thread (15) more from a stretched position in the second position (II) than in the first position (I).

12. Weft insertion device according to claim 11, wherein a plurality of thread deflection elements (51) are arranged next to one another in the thread extension direction (E) of the associated weft thread (15).

13. Weft insertion device according to one of claims 10 to 12, further comprising at least one controllable drive (52), wherein each thread deflection element (51) is motion-coupled to a drive (52).

14. Weft insertion device according to claim 13, wherein the at least one drive (52) is a piezoelectric drive (56) or a voice coil drive (57).

15. Weft insertion device according to one of the preceding claims, further comprising a controllable separating device (64) configured to sever an inserted weft thread (15).

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