Weft insertion device for a weaving machine

Abstract

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 configured to feed several different weft threads (15) from separate thread stores (18) and insert them by means of compressed air from a weft channel (27) of a weft insertion tube (26) into the shed (13) or the reed channel (16). A thread feed tube (39) with a thread feed channel (40) is provided for each of the different weft threads (15), with each thread feed channel (40) opening into the weft channel (27) at a feed opening (41). Thus, the same weft channel (27) is provided for all weft threads (15) to be inserted.Compressed air, which can be referred to as primary air (P), is introduced into the weft channel. This allows a terminal section (42) of the weft thread (15), located within the primary airflow (P), to be conveyed from the weft channel (27) and inserted into the shed or 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) with the reed channel (16) or the shed (13).

Description

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

[0002] The weft insertion device can optionally include one or more relay nozzles and / or a stretching nozzle. The weft thread inserted by the device is slowed down by air resistance and does not remain taut. The thread is then conveyed by airflow through several relay nozzles positioned along the reed channel until it reaches the opposite side of the fabric, where it can be held taut by the stretching nozzle until the reed is caught.

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

[0004] For example, DE 30 14 776 A1 describes a device for inserting weft threads into a shuttleless weaving machine using blow nozzles. The blow nozzles can be positioned one after the other in an insertion position with respect to the shed, for example, being mounted pivotably around a fixed point.

[0005] A weft insertion device for a nozzle weaving machine is known from DE 34 01 962 A1, which has at least two insertion nozzles. The insertion nozzles are connected to each other in the area of ​​the exit sides of the weft threads.

[0006] In weaving machines, it may be necessary to use several different weft threads, for example, weft threads of different colors and / or weft threads made of different materials. Air-jet weaving employs weft insertion devices for this purpose, which have a nozzle for each weft thread used in the weaving process. This nozzle uses air pressure to insert the respective weft thread into the reed channel. A disadvantage of this method is that only one of the available air nozzles—also called the main nozzle—can be optimally aligned with the reed channel. Since the reed channel has a relatively small cross-section, the air nozzles cannot be arranged parallel to each other along the extension of the reed channel. Therefore, it is necessary to arrange several or all of the air nozzles at an angle relative to the direction of the reed channel.Depending on the number of air nozzles used, inclinations of up to approximately 7° can occur relative to the desired weaving direction - i.e., the extension direction of the reed channel.

[0007] In previously known looms equipped for air-jet weaving, the energy consumption of the loom for operating the weft insertion device accounts for approximately 30% of the total energy consumption. Generating 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 negatively impacts the efficiency of weft thread delivery by compressed air, thereby increasing the compressed air requirement (pressure and duration of the compressed air discharge). Furthermore, there is a risk that an air nozzle inclined to the reed channel will cause the inserted weft thread to strike the reed, resulting in incomplete or incorrect insertion into the shed. This increases the likelihood of weft insertion errors.

[0008] To avoid this problem, Picanol nv offers a weft insertion device called "PosiJet," which uses a movable air nozzle assembly. Each air nozzle of the assembly is moved to a desired position relative to the reed channel before weft insertion to optimize the insertion direction of the weft thread into the reed channel. However, this solution requires a very complex design of the air nozzle assembly to enable it to move into the desired position quickly enough. This requires moving the entire mass of the air nozzle assembly.

[0009] Based on the known state of the art, the object of the present invention can be considered to be to create a more energy-efficient weft insertion device that enables high weaving speeds while maintaining a low error rate in weft insertion.

[0010] This problem is solved by a shot insertion device with the features of claim 1.

[0011] The weft insertion device according to the invention is designed to insert a weft thread in a weft direction into an open shed or a reed channel of a reed of a weaving machine. The weft insertion device operates with compressed air assistance. The weft thread to be inserted is fed into the open shed or reed channel by compressed air from a weft insertion tube. Optionally, further air delivery nozzles and / or suction devices can be provided along the reed channel and / or on a side of the reed channel opposite the weft direction to support or improve the weft thread guidance along the reed channel.

[0012] The weft insertion tube defines a weft channel. Specifically, there is a single weft insertion tube with a single weft channel. The weft insertion tube can be optimally aligned with 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 parallel or slightly inclined to the weft direction, depending primarily on the shape of the weft channel. The reed channel extends, in particular, along the longitudinal center axis of the weft channel.

[0013] The weft insertion device also has at least two yarn feed tubes. Each yarn feed tube defines a yarn feed channel. Each yarn feed channel opens into the weft channel of the weft insertion tube at a feed opening. An individual weft thread can be fed into the weft channel via each yarn feed channel. Depending on the number of yarn feed tubes or 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 several different weft threads in weaving via the weft insertion device, which differ, for example, in terms of color and / or titer and / or material. Specifically, exactly one weft thread is fed through each yarn feed channel.

[0014] There are various options for arranging the thread feed tubes or channels. The feed openings can be parallel to the longitudinal center axis of the weft channel and / or offset circumferentially around the longitudinal center axis of the weft channel, or arranged adjacent to one another. Depending on the chosen arrangement, in one embodiment, for example, all thread feed tubes and / or channels may be aligned parallel to a common plane. Alternatively, the thread feed tubes and / or channels may be arranged, for example, within a common virtual truncated cone surface or within several virtual truncated cone surfaces. The choice of arrangement depends, for example, on the number of desired or required thread feed channels.

[0015] The shot insertion device also includes an air duct pipe. The air duct pipe defines an air channel. In one embodiment, there is a single air duct pipe with a single air channel. Alternatively, there may be multiple air channels and / or multiple air duct pipes.

[0016] The at least one air channel is designed to supply compressed air to the weft channel and opens into it at an air channel opening. This air channel opening is located downstream of the yarn feed channels in the weft direction. Compressed air can be introduced into the weft channel via this air channel opening in the weft direction to propel the end section of a weft yarn present in the weft channel out of the channel and into the reed channel or the open shed.

[0017] The inventive design of the weft insertion device enables energy-efficient air-jet weaving. Because the air channel opening is arranged downstream of the feed openings in the weft direction, little or no compressed air escapes from the air channel through either of the feed openings into the respective yarn feed channel. The compressed air used to convey the weft yarn from the weft channel flows completely, or at least substantially completely, in the weft direction through the weft channel, i.e., towards the reed channel, and exits at the opening of the weft channel, entering at least partially into the reed channel. The weft channel can be optimally positioned relative to the reed channel.

[0018] It has been shown that, compared to previous weft insertion devices with air nozzles that are not optimally aligned from a flow perspective, significant energy savings of 2-3% or even up to 10% or 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 caused by the inserted weft thread striking the reed is minimized. The design of the weft insertion device according to the invention is considerably simpler than that using movable air nozzles. Several different weft threads can be inserted in rapid succession. In addition, it is also possible, in principle, to insert two or more weft threads simultaneously through the common weft channel into the reed channel or the open shed.

[0019] It is advantageous if the weft insertion device also has at least two yarn feeding units. Each yarn feed channel is assigned one yarn feeding unit. Each yarn feeding unit is configured to feed an end section of the assigned weft yarn into the weft channel. In one embodiment, the feeding of the end section of the weft yarn into the weft channel can be carried out by means of conveying air or at least with the aid of conveying air. For this purpose, each yarn feeding unit can have a conveying air connection through which conveying air can be directed into the assigned yarn feed channel. The conveying air flows through the respective yarn feed channel and the feed opening into the weft channel and then along the weft channel in the weft direction, whereby the end section of the weft yarn can be positioned at least partially behind the air channel opening in the weft direction.When air subsequently escapes through the air channel opening, the relevant weft thread is transported further in the weft direction.

[0020] 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 operate with negative pressure.

[0021] As previously explained, it is also possible to position the end section of a weft thread in the weft channel via multiple thread feed channels and to insert two or more weft threads simultaneously. Successive weft thread insertions can be performed at a high repetition rate or frequency, for example, 1000 insertions or more per minute.

[0022] A particularly advantageous design of the weft insertion device is one in which each thread feed channel is assigned a thread retraction unit. Each thread retraction unit is configured to move the end section of the assigned weft thread extending through the thread feed channel in a retraction direction within the weft channel, and in particular to move it behind the air channel opening. The thread retraction unit allows the end section of a weft thread used in the last weft insertion to be removed from the area between the air channel opening and the opening of the weft channel, thus freeing this area 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.

[0023] The thread retraction unit can have at least one thread deflection element for retracting the end section of the associated weft thread. This element can be moved between a first position and a second position. In the second position, the thread deflection element can deflect an associated section of the weft thread more than in the first position compared to a fully extended position. This greater deflection increases the path or length of a section of the weft thread that extends obliquely or perpendicularly to the direction of travel or inclination of the weft thread. This allows the end section of the weft thread in the weft channel to be moved in the retraction direction, opposite to the weft direction.

[0024] Depending on the available travel or stroke of the at least one yarn deflection element between the first and second positions, it may be necessary to provide several such yarn deflection elements in each yarn retraction unit to achieve a sufficient travel length for retracting the end section of the weft yarn. The yarn deflection elements can then, for example, be arranged side by side along the length of the associated weft yarn.

[0025] In one embodiment, the at least one thread deflection element can assume the first position as its starting position. It can, for example, be forced into the starting position or the first position by the force of gravity 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.

[0026] Each thread deflection element can be assigned a controllable drive to move between the first and second positions, or vice versa, and / or to hold the element in the first and / or second position. In particular, each thread deflection element can be assigned an individually controllable, separate drive. The drive can be, for example, a linear drive. The movement can be generated by a piezoelectric force from a piezoelectric drive or, for example, by a moving-coil drive. In a moving-coil drive, an armature inside a coil moves and is moved electromagnetically. Other electromagnetic drives can also be used.

[0027] It is also possible to group at least several thread deflection elements and assign a common drive to this group.

[0028] To cut a weft thread inserted into an open shed or reed channel, the weft insertion device can include a controllable cutting mechanism. The cutting mechanism can be positioned downstream of the weft channel opening in the weft direction, which simplifies the design. Alternatively, the cutting mechanism can be located in the area between the feed openings and the opening of the weft channel, for example, inside or on the weft insertion tube. The cutting mechanism can use mechanical cutting elements (such as a blade or cutting edge) or non-contact cutting elements, such as a laser, to separate the weft thread.

[0029] In an advantageous embodiment of the shot delivery device, at least one air nozzle can be provided in the airflow path to increase the airflow velocity in the firing direction, particularly within the air duct of the air duct pipe. The air nozzle can, for example, be designed as a Laval nozzle. This allows the airflow velocity to be increased to supersonic speeds.

[0030] The air duct pipe can have a single geometry or cross-sectional shape (e.g., rectangular, square, circular, etc.) along its entire length, or it can have at least one change in geometry and thus different cross-sectional shapes. This at least one change in geometry allows for even more effective airflow conditions, for example, to account for boundary layer processes, turbulence, flow separation, or similar flow effects. This applies not only to the air duct pipes but also to the weft channel pipe and / or the yarn feed pipe. Improved yarn transport can be achieved, especially when using multiple yarns with different properties (e.g., transport and yarn properties). This allows for the optimization and adjustment of yarn insertion and retention.

[0031] Advantageous embodiments of the invention will become apparent 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. The drawings show: Fig. 1 a highly schematic diagram of a part of a loom with a weft insertion device, Fig. 2 a highly schematic, block diagram-like representation of an embodiment of a shot insertion device according to the present invention, Fig. 3 to 5 the shot insertion device from Fig. 3 at different stages during the insertion of a weft thread or during weaving, Fig. 6 a highly schematic, block diagram-like representation of a further embodiment of a shot insertion device according to the invention, Fig. 7 an embodiment of a shot insertion device according to the invention in a schematic representation looking against a shot direction, Fig. 8 a highly schematic, block diagram-like representation of a further embodiment of a shot insertion device, Fig. 9 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 located in a first position, Fig. 10 the thread retraction unit from Fig. 9, wherein the thread deflection elements are in a second position, Fig. 11 a schematic representation of a drive for a thread deflection element made of Fig. 9 or Fig. 10 with an electromagnetic drive, Fig. 12 a schematic representation of a piezoelectric drive for a thread deflection element made of Fig. 9 or Fig. 10, Fig. 13 an embodiment of an air duct pipe of any embodiment of the shot insertion device comprising an air nozzle, and Fig. 14 and Fig. 15 each a highly schematic, perspective representation of a further embodiment of a shot insertion device according to the invention.

[0032] Fig. Figure 1 shows a highly schematic, simplified diagram of a part of a loom 10. The loom 10 has several heddles 11, which serve to guide warp threads 12. By positioning the heddles 11, a shed 13 can be opened.

[0033] 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 fed in a weft direction S through the weft insertion device 14, which is located in Fig. 1 is directed perpendicularly to the plane of the drawing towards the viewer. The weft thread 15 is, for example, inserted into the shed 13 along a reed channel 16 of a reed 17.

[0034] The insertion of a weft thread 15 means that a length of the weft thread 15 is inserted along the entire width of the shed 13. After insertion, the weft thread 15 is usually still connected to a yarn supply 18 from which the weft thread 15 was taken. The weft insertion device 14 can convey the weft thread 15 by means of compressed air. This method is also known as air-jet weaving.

[0035] By means of a separating device 64 ( Fig. 2-6) The weft thread 15 can be separated from the thread supply 18. Simultaneously, before, or after, 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 unwound by means of a take-up device 22 and, for example, wound onto a roll.

[0036] As shown schematically in Fig. As shown in Figure 1, when weaving with the weaving machine 10, several different weft threads 15 can be used from a separate thread supply 18 and inserted into the shed 13 or the reed channel 16 by means of the weft insertion device 14.

[0037] A weft insertion device 14, designed for air-jet weaving and which inserts the weft threads 15 into the shed 13 based on compressed air, is arranged according to a block diagram in Fig. Figure 2 shows the weft insertion device 14 having 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 from the weft channel opening 28 and inserted into the shed or the reed channel 16.

[0038] The shot insertion device 14 also has an air duct pipe 29, which is located in the Fig. In the embodiment shown in Figure 2, the air duct extends parallel to the longitudinal center axis A or coaxially to the longitudinal center axis A. The air duct pipe 29 defines an air duct 30, which opens into the shot duct 27 at an air duct opening 31. The air duct opening 31 is located upstream of the shot duct opening 28 when viewed in the shot direction S. A longitudinal section of the shot duct 27 in the shot direction S between the air duct opening 31 and the shot duct opening 28 can be designated as the main flow section 32. Compressed air from a pressure source 33 upstream of the air duct opening 31 can be supplied to the air duct 30. This compressed air serves to introduce the weft thread 15 and can be designated 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 duct 30.By means of the first valve 35, the control device 34 can control the supply of primary air P to the air duct 30, in particular interrupt or release it.

[0039] The shot insertion device 14 also has several thread feed tubes 39, of which only by way of example in Fig. Figure 2 illustrates two thread feed tubes 39. 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, such that the loose or free end of the weft thread 15 is located within the weft channel 27, as shown schematically in Figure 2. Fig. 2 is shown. In an initial state of the shot 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 the shot direction S in front of the air duct opening 31.

[0040] To convey a loose end and a subsequent end section 42 of an associated weft thread 15 into the main flow section 32, each thread feed channel 40 is assigned a thread conveying unit 43. In the exemplary embodiment, the thread conveying unit 43 conveys the associated weft thread 15 into the respective thread feed channel 40 by supplying conveying air F. For this purpose, each thread feed channel 40 or thread feed tube 39 has a conveying air connection 44, which is part of the respective thread conveying unit 43. The conveying air F flowing in the thread feed channel 40 carries the section of the weft thread 15 located there and conveys it along the thread feed channel 40 via the respective feed opening 41 into the weft channel 27.The length of the weft thread 15 arranged within the shot channel 27 (measured from the loose or free end of the weft thread 15) increases, so that the loose or free end of the respective weft thread 15 can be positioned in the area of ​​the main flow section 32 of the shot channel 27. The introduced conveying air F can escape from the shot channel opening 28.

[0041] Each yarn feeder unit 43 can be individually controlled by the control unit 34 to feed the respective assigned weft yarn 15 into the weft channel 27 individually and independently of the at least one other weft yarn 15. 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 via a secondary valve 45 controllable by the control unit 34, or fluidically disconnected from the pressure source 33.

[0042] In the Fig. 14 and Fig. Figure 15 schematically illustrates another embodiment of a shot insertion device 14. In this embodiment, the air channel tubes 29 are arranged circumferentially around the longitudinal center axis A. Similarly, the thread feed tubes 39 are also arranged circumferentially around the longitudinal center axis A. In contrast to the illustration, there may also be more or fewer air channel tubes 29 and / or thread feed tubes 39.

[0043] The pressure source 33 exhibits the following characteristics in the embodiments according to Fig. 14 and Fig. Figure 15 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.

[0044] In the exemplary embodiment according to Fig. In section 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 designed in an annular form and coaxially surrounds the longitudinal central axis A.

[0045] In the exemplary embodiment according to Fig. 15 Each air duct pipe 29 is assigned a separate pressure accumulator 33b, to which each air duct pipe 29 is fluidically connected. Analogous to the embodiment according to Fig. 14. The pressure accumulators 33b are fluidically connected to a pressure generation unit 33a. The pressure accumulators 33b are shown cylindrically for illustrative purposes only. They can be arranged analogously to the embodiment shown in the following. Fig. 14 can also be arranged in a ring around the longitudinal central axis A. The exemplary embodiments of the Fig. 14 and Fig. 15 can thus be combined with one another. In a further variation, several pressure accumulators 33b can be present, whereby more than one air duct pipe 29 can be fluidically connected to each pressure accumulator 33b.

[0046] In the exemplary embodiments according to the Fig. 14 and Fig. 15 The arrangement of the air duct pipes 29 and / or the thread feed pipes 39 can correspond to any embodiment described above, as is particularly relevant in connection with the Fig. 2-8 was explained.

[0047] In the Fig. 14 and Fig. For the sake of clarity, the valves 35 and 45 are not illustrated and may 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 respective connected air duct pipe 29.

[0048] If several pressure accumulators 33b are present, in particular one pressure accumulator 33b 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 coiling technique.

[0049] If several air duct pipes 29 are connected to a pressure accumulator 33b, the pressure accumulator 33b can optionally be pressurized by different bridges, depending on which connected air duct pipe 29 is to be pressurized next with the stored compressed air. Similarly, several pressure accumulators 33b can be pressurized with different pressures. Appropriate devices, such as valves or the like, can be provided for this purpose in the fluid connection between the pressure generating unit 33a and the pressure accumulators 33b.

[0050] In general, in all embodiments of the shot insertion device 14, the geometric design of the shot channel 27 and / or the at least one air duct tube 29 and / or the thread feed tubes 39 can be arbitrarily configured. The cross-sectional geometry can change in the direction of extension of the respective tube or it can remain constant. For example, the cross-sectional shape can always be polygonal or always circular. Optionally, it can also change from a polygonal shape to a circular shape, resulting in a geometric transition. In general, the geometry and the number of optional geometric transitions are freely selectable and adaptable to the specific application. The geometric design allows for the optimization and efficiency of the thread feed and flow conditions.

[0051] To move a terminal section 42 of a weft thread 15, located in the main flow section 32, out of the main flow section 32 in a retraction direction R opposite to the weft direction S, 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.

[0052] An exemplary embodiment of a thread retraction unit 50 is shown in a highly schematic form in the Fig. 9 and Fig. Figure 10 illustrates the yarn retraction unit 50, which can have one yarn deflection element 51 and preferably several yarn deflection elements 51, which are inclined or perpendicular to a yarn extension direction E between a first position I ( Fig. 9) and a second position II are movable. The thread extension direction E defines a direction that corresponds to an extension position of the section of the weft thread 15 that extends in the area of ​​the thread retraction unit 50.

[0053] 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 existing thread deflection elements 51, so that the thread deflection elements 51, which are coupled to different drives 52, can be moved or positioned individually from one another.

[0054] At the in Fig. 9 and Fig. In the illustrated embodiment of the thread retraction unit 50 in Figure 10, one of the thread deflection elements 51 serves as a clamping element 51a, which is configured 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 positioned at a distance opposite 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.

[0055] The clamping element 51a is arranged on the side of the thread retraction unit 50 that is furthest 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 shown in the Fig. 9 and Fig. As shown schematically in Figure 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 overlapping in the second position II, so to speak, in a toothed-like manner.

[0056] The thread retraction unit 50 according to the embodiment of the Fig. 9 and Fig. 10 basically works as follows:

[0057] If an end section 42 of a weft thread 15 is to be retracted, the clamping element 51a is first moved to the second position II. This prevents any force from being applied to the weft thread 15, which would lead to the weft thread 15 being fed from the thread supply 18. Subsequently, or alternatively at least partially simultaneously, the movement of the other thread deflection elements 51 from the first position I ( Fig. 9) towards the second position II ( Fig. 10) triggered or carried out. The section of the weft thread 15 running in the area of ​​the thread retraction unit 50 is thereby deflected more strongly from its thread extension direction E compared to the first position I, causing the end section 42 or the loose end of the weft thread 15 to move in the retraction direction R in the weft channel 27 and, for example, be pulled out of the main flow section 32. The distance traveled by each thread deflection element 51 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 distance of the loose end of the weft thread 15.

[0058] A linear drive 54, for example an electromagnetic drive 55, can be used as a drive for the thread deflection element 51 or thread deflection elements 51 ( Fig. 11) or a piezoelectric drive 56 ( Fig. 12) The electromagnetic drive 55 can, for example, be 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 coupled to the thread deflection element 51, for example, by being rigidly connected. A current i can be initiated to flow through the coil 58 via the control device 34, thus generating a magnetic field that in turn moves the armature 59. Depending on the direction of current i, the movement of the armature 59 can optionally also be electromagnetically induced in opposite directions, for example, from the first position I to the second position II, and vice versa.

[0059] The schematic in Fig. The piezoelectric drive 56 shown in Figure 12 has a piezoelectric factor 60, to which the control device 34 can apply a voltage u in order to deform the piezoelectric factor 60 based on the piezoelectric effect in the direction in which the thread deflection element 51, which is coupled to the movement of 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 and II can thus be initiated.

[0060] Using the exemplary in Fig. 11 and Fig. The drives 54 shown in Figure 12 enable very high frequencies of movement of the thread deflection element 51 to be achieved. The retraction of the weft thread in the retraction direction R can therefore be sufficiently fast even for high-speed weaving machines.

[0061] The in Fig. The weft insertion device 14 shown in Figure 2 also has a cutting device 64 that can be controlled by the control unit 34. The cutting device 64 is designed to cut 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 cut, it has a loose end immediately adjacent to the cutting device 64, to which the end section 42 is attached.

[0062] The separating device 64 is in the Fig. 2-6 schematically illustrates this. It can have a mechanical blade or cutting edge for cutting the weft thread 15. Alternatively or additionally, the cutting device 64 can also use a laser beam to cut the weft thread 15, as schematically illustrated in Figure 2-6. Fig. Figure 8 shows that the separating device 64 can be arranged behind the firing channel opening 28 in the firing direction S, as shown in the embodiments according to the Fig. 2-6 is the case. 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 duct opening 31 ( Fig. 8).

[0063] The components of the shot insertion device 14 that can be controlled by the control unit 34 are indicated in the drawing by the dashed arrows. The control unit 34 uses, for example, electrical and / or electronic signals to control these components. The control unit 34 can include a microprocessor to execute control commands and control the shot insertion device so that a desired process sequence is achieved for shot insertion. The process or process sequence is described below based on the Fig. 2-5 explained.

[0064] In Fig. Figure 2 illustrates the initial position or situation. The weft threads 15, with their loose ends and the adjoining end sections 42, are arranged outside the main flow section 32, with the loose ends located in the firing direction S in front of the air duct opening 31 in the firing channel 27.

[0065] In order to insert a weft thread from the weft channel 27 into the shed 13 or the reed channel 16, the thread feed unit 43 assigned to this weft thread 15 is first activated. For example, conveying air F is directed into the relevant thread feed channel 40, in the exemplary embodiment into the Fig. 3. Thread feed channel 40 shown below. 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., viewed in the weft direction S, behind the air channel opening 31. 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 direct primary air P into the air channel 30, which exits into the main flow section 32 and moves the end section 42 of the weft thread 15 located there in the weft direction S. This moves the loose end of the weft thread 15 out of the weft channel 27 and further into the shed 13 or the reed channel 16. This situation is shown schematically in Fig. 3 illustrated.

[0066] After the weft thread 15 has passed through the shed 13 or the reed channel 16 and the loose end is 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 ( Fig. 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 with the Fig. This is the case in the embodiment shown in Figures 2-5. To enable the trouble-free insertion of another weft thread 15, the loose end or end section 42 of the last inserted weft thread 15 is therefore retracted from the main flow section 32 in the retraction direction R, opposite to the weaving direction S. For this purpose, the thread retraction unit 50 associated with the weft thread 15 is actuated, as shown schematically in Figure 2-5. Fig. 5 is shown. After completion of the withdrawal movement, the end section 42 is again arranged outside the main flow section 32, so that the in Fig. This results in two schematically represented initial situations.

[0067] In a modified embodiment, the at least one thread retraction unit 50 can be omitted if the cutting 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 located outside the main flow section 32 immediately after being cut. The rear end of the inserted weft thread 15, which is assigned to the weft insertion device 14 after being cut, can be completely removed from the weft channel 27 by an airflow, for example, by the primary air P, another airflow, or in another suitable manner, if necessary.

[0068] Another option is to cut the weft thread 15 at several points after it has been inserted into the shed 13, for example at one point between the fabric 21 and the weft channel opening 28 and at another point in the weft direction S before the main flow section 32. A remaining piece of weft thread that remains between these two cut points can then also be removed from the weft channel 27 by an airflow or in some other way.

[0069] As already explained, the number of weft threads used, and therefore the number of thread feed tubes 39 or thread feed channels 40, can vary. The illustrations in the drawing are merely examples. While in the Fig. Figures 2-5 show two weft threads 15 and two thread feed channels 40. Fig. 6. For example, four different weft threads 15 and four thread feed channels 40 can be entered. Generally, 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. The following is shown only as an example: Fig. Figure 7 shows an embodiment of a shot 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 are arranged, for example, in a regularly distributed manner.

[0070] In another embodiment, which is schematically shown in Fig. As illustrated in Figure 8, instead of a central air duct pipe 29 or a central air duct 30, the primary air P can be supplied via several separate air duct pipes 29 or air ducts 30. The thread feed channels 40 can, for example, open laterally into the shot channel 27 behind the feed openings 41 in the direction of the shot S, as shown in Figure 8. Fig. 8 shows an example.

[0071] 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 Fig. Figure 13 shows that the air nozzle 65 can be designed as a Laval nozzle. The primary air P can be accelerated to supersonic speed after passing through the air nozzle 65.

[0072] As an alternative to the arrangement or design of the air nozzle 65 in the air duct 30, the air nozzle 65 can be arranged or designed in the flow path of the primary air P in the shot channel 27, as shown by dashed line in the example. Fig. 8 is shown.

[0073] 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 configured to feed several different weft threads 15 from separate thread stores 18 and insert them into the shed 13 or 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, with each thread feed channel 40 opening into the weft channel 27 at a feed opening 41. Thus, the same weft channel 27 is provided for all weft threads 15 to be inserted. Via 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 airflow of the primary air P, can be conveyed from the weft channel 27 and into the shed orThe reed channel 16 is entered. 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. Reference symbol list: 10 weaving machine 11 Webschaft 12 warp threads 13 Webbox 14 shot insertion device 15 weft threads 16 Websheet Channel 17 Websheet 18 thread supply 19 Separating device 20 fabric edge 21 tissues 22 Extraction device 26 shot entry tube 27 shot channel 28 Shot channel mouth 29 air duct pipe 30 air duct 31 Air duct opening 32 Main flow section 33 Pressure source 33a Pressure generation unit 33b Pressure accumulator 34 Control unit 35 Primary valve 39 Thread feed tube 40 Thread feed channel 41 Inlet 42 Final section 43 Thread feeder unit 44 Conveying air connection 45 Secondary valve 50 thread retraction units 51 Thread deflection element 51a Clamping element 52 Drive 53 Stop surface 54 Linear drive 55 electromagnetic drive 56 piezoelectric drive 57 Moving coil drive 58 coil 59 anchors 60 Piezoelectric factor 64 Separating device 65 Air nozzle A longitudinal center axis E Thread extension direction F Conveying air i electricity P Primary air S direction of fire R Retreat direction and voltage I first position II second position

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 shot insertion tube (26) defining a shot channel (27), - at least two thread feed tubes (39), each of which defines a thread feed channel (40), each thread feed channel (40) opening into the weft channel (27) at a feed opening (41), and each thread feed channel (40) being designed to feed a weft thread (15) to the weft channel (27), - at least one air duct pipe (29), each of which delimits an air duct (30), each air duct (30) opening into the firing channel (27) at an air duct opening (31), the air duct opening (31) being arranged behind all existing supply openings (41) in the firing direction (S). [2] Weft insertion device according to claim 1, wherein only a single weft insertion tube (26) with a single weft channel (27) is provided. [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 designed to convey an end section (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 designed to convey the end portion (42) of the weft thread (15) into the weft channel (27) to such an extent 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 designed to convey the end portion (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 duct tube (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). [8] Weft insertion device according to one of the preceding claims, which is designed to insert several weft threads (15) simultaneously into the reed channel (16). [9] 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 designed to retract an end portion (42) of the weft thread (15) counter to the weft direction (S) in a retraction direction (R). [10] Weft insertion device according to claim 9, 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 section of the weft thread (15) in the second position (II) more from a stretched position than in the first position (I). [11] Weft insertion device according to claim 10, 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). [12] Weft insertion device according to one of claims 10 to 11, further comprising at least one controllable drive (52), wherein each thread deflection element (51) is motion-coupled to a drive (52). [13] Weft insertion device according to claim 12, characterized in that the at least one drive (52) is a piezoelectric drive (56) or a voice coil drive (57). [14] Weft insertion device according to one of the preceding claims, further comprising a controllable separating device (64) which is arranged to sever an inserted weft thread (15).

Images