TECHNICAL FI ELD AND PRIOR ART

[0001 ] The invention relates to an arrangement and a method for optimizing a weaving process. More particular, the invention relates to an arrangement and a method for avoiding weaving errors due to an incorrect threading of a weft thread preparation device of a weaving machine.

[0002] A fabric consists of warp threads and weft threads. In a weaving machine, the weft threads are inserted in between warp threads during an insertion cycle of the weaving process. Weft threads are fed to the weaving machine and are wound on bobbins, which are typically placed on bobbin racks or bobbin creels arranged on one side of the weaving machine, generally on the left side. Before starting to weave a new fabric style, a weaving machine has to be equipped with raw materials. Starting from the rack, the weft thread of each bobbin is manually threaded to a prewinder that prepares the weft thread for the weft insertion. A weaving machine can have one prewinder or up to twelve prewinders. Usually, one prewinder contains weft thread coming from one bobbin. In so called multi thread weaving applications, two or more weft threads coming from an associated bobbin can be wound simultaneously to a common prewinder. Also, in so called multi thread weaving applications, two or more weft threads coming from an associated prewinder can be inserted simultaneously in a weaving shed, for example by means of a gripper or a main nozzle. Often, a leading end of a second bobbin is tied to the trailing end of a first bobbin, to enable longer machine running cycles without interventions to supply new bobbins. For example, a weaving machine is equipped with twelve prewinders and with one or more racks that form together twelve platforms for bobbins, wherein each platform comprises one or two pins, on which a bobbin is placed.

[0003] In a control device for the weaving machine so called machine channels or weft insertion channels are used to determine the sequence by which the different weft threads are inserted. This sequence is often referred to as a "color pattern". One or more element(s) is/are assigned to each virtual channel, which is/are driven by the control device to withdraw a weft thread from a bobbin and/or to insert a weft thread threaded or otherwise coupled to said element. In the context of the application, said elements assigned to virtual channels are referred to as weft insertion channel elements. [0004] In a gripper weaving machine, also named rapier weaving machine, weft threads are manually threaded to prewinders of a weft thread preparation device and are threaded from the prewinders through weft thread brakes to one weft thread presenter. The weft thread presenters and the prewinders are driven by the control device in order to wind the weft thread to the prewinder and thereby to draw off weft thread from the bobbin, and/or to present a particular weft thread to a bringer gripper for an insertion of said weft thread. In this case, the weft insertion channel elements comprise the prewinders and the weft thread presenters.

[0005] In an airjet weaving machine, weft threads from prewinders are fed to one or a set of main nozzles, wherein the main nozzles are driven by the control device in order to select the weft thread to be inserted during a weaving machine cycle. In this case, the weft insertion channel elements comprise the prewinders and the main nozzles. [0006] In order to have a control device that regulates the complete insertion process, it is essential that the type of the weft thread threaded to the weft insertion channel element(s) and, thus, added to a weft insertion channel is known. In the context of the application "threaded to a weft insertion channel element" means that weft thread is coupled along its movement path in a certain way to the weft insertion channel element. [0007] From US 2004/0133297 A1 it is known to provide bobbins with identification elements, and to identify a bobbin provided on a platform, wherein the identification of the bobbins is used in order to weave an article according to a weft insertion pattern that is determined as a function of the kind of the weft threads. A weft insertion pattern can be entered in a machine terminal or a central server as a function of the kind of the weft thread to be inserted. Using the identification elements and the knowledge about the path of the weft thread in the weaving machine, in particular the knowledge about the prewinder and the main nozzle or weft thread presenter used for a particular weft thread coming from the bobbin rack, the weaving machine can determine, for each kind of weft thread, the weft insertion channel corresponding to that kind of weft thread, and can convert the entered weft insertion pattern as a function of the kind of the weft thread to a weft insertion pattern as a function of the weft insertion channels.

[0008] However, even with such identification elements there remains the risk that the weft thread is threaded to a different prewinder than assumed in the control device and, hence, the weft thread property is added to an incorrect weft insertion channel. SUMMARY OF THE I NVENTION

[0009] It is therefore, the object of the present invention to provide an arrangement and a method for avoiding weaving errors due to an incorrect threading of a weft thread preparation device of a weaving machine. [0010] This object is solved by the arrangement and the method with the features of claims 1 and 8. Preferred embodiments are defined in the dependent claims.

[001 1 ] According to a first aspect of the invention an arrangement for optimizing a weaving process is provided, the arrangement comprising a control device, a number of weft insertion channel elements, each weft insertion channel element being allocated in the control device to one weft insertion channel, and a bobbin rack with a number of platforms each having a weft thread property identifying sensor, wherein weft threads of bobbins placed on at least some of the platforms are fed to at least some of the weft insertion channel elements, wherein at least at some of the platforms, and preferably on all platforms, a weft thread movement detector arranged for detecting a weft thread movement is provided, and wherein the control device is arranged

a) to drive at least one of the weft insertion channel elements for drawing off at least one of the weft threads fed to said weft insertion channel element from the associated bobbin placed on a platform,

b) to determine the platform of the bobbin from which the at least one of the weft threads is drawn off by evaluating detector signals of the weft thread movement detectors provided at the platforms, and

c) to identify at least one weft thread property of the at least one weft thread fed to the weft insertion channel element by evaluating a sensor signal of the weft thread property identifying sensor provided at the determined platform. [0012] Platforms may be provided with one pin or more than one pin, in particular two pins. On each pin of each platform a weft thread property identifying sensor can be provided. In theory, a weft thread from a bobbin placed on any pin of any platform could be manually threaded or otherwise coupled to any of a number of prewinders and from the prewinder to any of the number of further weft insertion channel elements, for example to a weft thread presenter or a main nozzle. In practice, there are some spatial limitations. Nevertheless, in many weaving machines weft threads fed from at least some of the bobbins placed on the platform can be manually threaded or otherwise coupled to at least two different prewinders without difficulty. This may result in weaving errors. If for example, for weaving a certain weaving pattern, the control device assumes that a first weft thread of a first type has been threaded to a first prewinder and a second weft thread of a second type has been threaded to a second prewinder, however, when setting up the weaving machine the first weft thread of a first type is threaded to the second prewinder and a second weft thread of a second type is threaded to the first prewinder, this will result in a weaving error, which cannot be detected with prior art control devices. According to the invention, the platforms of the bobbins from which weft threads are drawn off are determined by means of the control device and properties of the weft thread arranged on the determined platform are identified. This allows for an unambiguous determination of weft thread properties inserted using weft insertion channel elements allocated in the control device to a particular weft insertion channel. Thereby, the actual set-up of the weaving machine can be determined, and, weaving errors can be avoided.

[0013] Suitable weft thread movement detectors may be chosen by the person skilled in the art. In one embodiment, an optical detector is provided for detecting a ballooning or movement of a weft thread during operation. In another embodiment, a piezo-electronic detector is provided for detecting an electrical charge induced upon the movement of the weft thread. In another embodiment, a detector using capacitive effects is provided, wherein for example a change in the capacitance upon movement of the weft thread is detected. In still another embodiment, natural electrical charges on the weft thread are detected using for example charge detectors. Suitable detectors are described for example in EP 0195469 A2 and/or US 4215728 A, which are incorporated herein by reference. However, the invention is not limited to the use of such detectors.

[0014] In one embodiment, a human machine interface comprising at least one of an audio output, a display device and a display is provided, wherein weft thread properties identified by the control device are indicated, in particular visualized, at the human machine interface to a user.

[0015] In preferred embodiments, the control device is further arranged to compare identified weft thread properties to weft thread property information allocated to weft insertion channels in the control device. As mentioned above, the weft insertion channels are used in the control device to determine the sequence by which the different weft threads are inserted and the weft insertion channel elements assigned to the weft insertion channels are driven accordingly. When comparing identified weft thread properties to weft thread property information allocated to weft insertion channels in the control device weaving errors resulting from an incorrect threading can be avoided. For example, in case the control device has identified that a red weft thread is threaded to the weft insertion channel element added to a first weft insertion channel, however for weaving a particular weaving pattern a green weft thread has to be inserted using said weft insertion channel elements, an error message can be generated and weaving may be inhibited until the threading is corrected.

[0016] In one embodiment, the control device is arranged for adjusting an allocation of weft insertion channel elements to a weft insertion channel based on an identified threading of a weft thread. For example, if a first prewinder has been assumed to insert a weft thread coming from a first platform, however, the weft thread has been threaded to a second prewinder, the second prewinder will be allocated to the weft insertion channel instead of the first prewinder. In alternative or in addition, the control device is arranged for adjusting a weaving sequence of weft thread of a weft insertion channel for weaving a particular weaving pattern based on identified weft thread properties. For example, in case the control device has identified that a red weft thread is threaded to the weft insertion channel element allocated to a first weft insertion channel, however for weaving a particular weaving pattern a green weft thread is required, and a green weft thread is threaded to the weft insertion channel element allocated to a second weft insertion channel, however for weaving a particular weaving pattern a red weft thread is required, in the weaving sequence the first weft insertion channel and the second weft insertion channel are exchanged. Of course, such an adjustment is not possible in case that no red weft thread has been provided.

[0017] The weft thread property identifying sensors are arranged to identify at least one weft thread property selected from the group comprising amongst others thread thickness, thread hairiness, thread twist, thread color, thread production time, thread supplier and/or thread material. In one embodiment, the weft thread property identifying sensors each comprise a contactless reader element arranged for reading data that is associated with a weft thread property from a tag attached to a bobbin placed at the associated platform. Reader elements and tags allow for a simple communication of a large number of weft thread properties of the weft threads wound to a bobbin. This allows the use of expert knowledge related to the physical properties of the weft thread in the control device. The reader element in one embodiment is an optical reader element, for example a barcode reader element or a QR code reader element. In preferred embodiments, radio frequency technology is applied, and in particular an RFI D reader element is provided. In alternative or in addition, sensors detecting the color, the hairiness or other weft thread properties may be provided. It is well known to provide more than one bobbin on a common platform, wherein a trailing end of a first bobbin is attached to the leading end of a second bobbin. In case several bobbins are placed on a common platform, in one embodiment only the weft thread properties of the first bobbin from which the weft thread is unwound is identified. In preferred embodiments, the weft thread property identifying sensors each are arranged for reading data from the tags attached to each bobbin placed at any one of the pins of the associated platform and/or for each bobbin placed at any one of the pins of the associated platform an associated weft thread property identifying sensor is provided.

[0018] According to preferred embodiments, the weft insertion channel elements of each weft insertion channel comprise a prewinder, wherein the weft thread of at least one bobbin placed on the bobbin rack is fed to one prewinder. Depending on the weaving pattern, all platforms or only some of the platforms are equipped with one or more bobbins. The weft threads of the bobbins are threaded to a prewinder and the prewinder is driven by the control device to prepare the weft thread for a weft insertion and, thereby, to draw off weft thread from the said bobbin. In case the control device drives one prewinder to draw off weft thread from a bobbin, but no weft thread movement is detected at the platform assumed by the control device, an error message can be generated. In alternative, the control device evaluates detector signals of several weft thread movement detectors provided at the platforms and determines the platform from which the weft thread is drawn off. [0019] In one embodiment, the weft insertion channel elements of each weft insertion channel comprise a prewinder and a second weft insertion channel element downstream of the prewinder, wherein a weft thread coming from at least one of the prewinders can be fed to at least two different second weft insertion channel elements, and wherein the control device is arranged to determine for each second weft insertion channel element the supplying prewinder. For this purpose, in one embodiment, a weft thread movement detector is provided for detecting the drawing off of weft thread from the prewinder. In known airjet weaving machines, the prewinders and the main nozzles arranged downstream of the prewinders are arranged in such manner that threading of a weft thread coming from one prewinder to a particular main nozzle in most cases is ensured. However, in particular in gripper weaving machines, a weft thread coming from a prewinder may be threaded to different weft presenters without difficulty. According to an embodiment of the invention, it is determined to which prewinder as well as to which weft presenter a particular weft thread is threaded. Hence, weaving errors can be avoided.

[0020] According to a second aspect a method is provided for optimizing a weaving process in a weaving machine comprising a control device, a number of weft insertion channel elements, each weft insertion channel element being allocated in the control device to one weft insertion channel, and a bobbin rack with a number of platforms each having a weft thread property identifying sensor, wherein a bobbin is placed on any one of the pins of any one of the platforms of the bobbin rack and the weft thread of said bobbin is fed to one of the number of weft insertion channel elements. The method comprises driving at least one weft insertion channel element by means of the control device to draw off the at least one weft thread fed to said weft insertion channel element from the associated bobbin placed on the bobbin rack, wherein upon or after drawing off the weft thread from said bobbin, the platform of said bobbin from which the at least one weft thread is drawn off is determined by evaluating detector signals of weft thread movement detectors arranged for detecting a weft thread movement, which are provided at at least some of the platforms, and at least one weft thread property of the at least one weft thread fed to the weft insertion channel element is identified by evaluating a sensor signal of the weft thread property identifying sensor provided at the determined platform. [0021 ] As described above, by determining the platform from which a weft insertion channel element draws off a weft thread, and by identifying the weft thread properties of the weft thread wound to a bobbin at said platform, weaving errors can be avoided reliably.

[0022] In one embodiment, weft thread properties identified by the control device are indicated, in particular visualized, to a user on a human machine interface. This allows the user to take action, when required.

[0023] In preferred embodiments, the identified weft thread properties are compared by means of the control device to weft thread property information allocated to weft insertion channels in the control device. In case the identified weft thread properties do not match with the weft thread property information, an error message can be generated and weaving can inhibited until a user has corrected the threading.

[0024] In alternative or in addition, in one embodiment, the control device adjusts the allocation of a weft insertion channel element to a weft insertion channel based on an identified threading of the weft thread. This could be done either by the control device without further notification to the user or only after the user has approved the adjustment. [0025] In one embodiment, a user is prompted to modify a position of two or more bobbins on the bobbin rack to optimize weaving a given weaving pattern. For example, it might be favorable to thread a weft thread dominating a particular weaving pattern to a weft presenter travelling only over a short distance when presenting a weft thread. The user can opt on following the proposed modification or maintaining a set-up. [0026] In one embodiment, weft thread properties are read by means of the weft thread property identifying sensor from a TAG attached to the bobbin from which the weft thread is drawn off, wherein in particular the weft thread properties are read using a contactless reader element, in particular an RFID reader element. The weft thread properties may comprise amongst others information about the weft thread, such as color, thickness, hairiness and/or its production date, as well as its spinning date as its bobbin date. The determination of such weft thread properties also allows, for example, to start-up a weaving machine with specific settings that are stored in the control device of the weaving machine for weft threads with such weft thread properties.

[0027] In preferred embodiments, the weft insertion channel elements of each weft insertion channel comprise a prewinder, wherein the platform of the bobbin from which a weft thread is drawn off by the prewinder is identified.

[0028] As mentioned above, there are arrangements in which the weft insertion channel elements of each weft insertion channel comprise a prewinder and a second weft insertion channel element downstream of the prewinder, wherein a weft thread coming from at least one of the prewinders can be fed to at least two different second weft insertion channels elements. In this case, in preferred embodiments for each second weft insertion channel element the supplying prewinder is determined by means of the control device.

BRI EF DESCRIPTION OF THE DRAWINGS

[0029] Further characteristics and advantages of the invention will emerge from the following description of the embodiments schematically illustrated in the drawings. Throughout the drawings, the same elements will be indicated by the same reference numerals.

Fig. 1 shows an arrangement for optimizing a weaving process at a gripper weaving machine.

Fig. 2 shows the arrangement of Fig. 1 with a different configuration.

Fig. 3 shows a display content for an arrangement similar to Fig. 1 during a threading. Fig. 4 shows a display content for an arrangement similar to Fig. 1 with another threading.

Fig. 5 shows a display content for an arrangement similar to Fig. 1 with an incorrect threading. Fig. 6 shows the arrangement of Fig. 1 with another different configuration.

Fig. 7 shows an arrangement for optimizing a weaving process at an airjet weaving machine.

DETAI LED DESCRI PTION OF EMBODIMENTS [0030] Fig. 1 schematically shows an arrangement 1 for a gripper weaving machine. The gripper weaving machine comprises a bringer gripper 2 and a receiver gripper 3. For weaving a fabric 4, weft threads are inserted into a shed formed by warp threads 5.

[0031 ] The arrangement 1 comprises a control device 6. The control device 6 in one embodiment is the central control device of the weaving machine. In other embodiments, a separate control device communicating with the central control device is provided. The arrangement 1 shown in Fig. 1 comprises a number of prewinders 7, 8, 9, a weft presenter device 10 with a number of weft presenters 1 1 , 12, 13 and a bobbin rack 14 with a number of platforms 15, 16, 17, each having two pins, wherein a bobbin 18, 19, 20, 21 , 22, 23 is provided at each pin. In the embodiment shown, three prewinders 7, 8, 9, three weft presenters 1 1 , 12, 13 and three platforms 15, 16, 17 are provided. In other embodiments, less than three or more than three, in particular up to twelve prewinders, weft presenters and platforms are provided.

[0032] Weft threads wound to a first bobbin 18, 20, 22 of each platform 15, 16, 17 are threaded to a prewinder 7, 8, 9 and are threaded from the prewinder 7, 8, 9 through weft thread brakes (not shown) to the associated weft presenter 13, 12, 1 1 . The trailing ends of the first bobbins 18, 20, 22 are tight to leading ends of the second bobbins 19, 21 , 23. Each bobbin 18, 19, 20, 21 , 22, 23 may in principle be used as "first bobbin".

[0033] At least one weft thread property identifying sensor 24, 25, 26 is provided at each platform 15, 16, 17. Preferably, at each bobbin of each platform an associated weft thread property identifying sensor is provided. Further, a weft thread movement detector 27, 28, 29 arranged for detecting a weft thread movement is provided at each platform 15, 16, 17. The weft thread property identifying sensors 24, 25, 26 and the weft thread movement detectors 27, 28, 29 communicate with the control device 6. The communications can be either wired or wireless. In the embodiment shown, additional weft thread movement detectors 30, 31 , 32 are provided downstream of each prewinder 7, 8, 9. Further, a human machine interface 33 for data input and data output is provided. A human machine interface 33 may consist of a computer, a tablet, a smartphone, a smartwatch, and such apparatuses. [0034] The prewinders 7, 8, 9 are driven by the control device 6 to prepare the weft thread for the weft insertion by winding the weft thread to the prewinder 7, 8, 9, and, thereby, draw off weft thread from the respective bobbin 18, 20, 22. For a weft insertion of a particular weft thread, the respective weft presenter 1 1 , 12, 13 is driven by the control device 6 to present the weft thread to the bringer gripper 2 and the weft thread is inserted by means of the bringer gripper 2 into the shed.

[0035] Each prewinder 7, 8, 9 and each weft presenter 1 1 , 12, 13 is assigned in the control device 6 to a weft insertion channel, also named weaving machine channel. These weft insertion channels are used in the control device 6 and determine the sequence by which the different weft threads are inserted.

[0036] Before starting up a new fabric style, the weaving machine has to be equipped with raw materials. When threading the weft threads of the bobbins arranged on the platform to the prewinders 7, 8, 9 and/or are threaded from the prewinders 7, 8, 9 to the weft presenters 1 1 , 12, 13, different configurations are possible. [0037] Fig. 2 shows a possible alternative configuration of the arrangement 1 of Fig. 1 . The configuration of Fig. 2 differs from that shown in Fig. 1 , in that a weft thread coming from a bobbin 20 arranged in the middle is threaded to a prewinder 9 arranged at a bottom side and a weft thread coming from a bobbin 22 arranged at a bottom side is threaded to a prewinder 8 arranged in the middle. Of course, such an arrangement is only possible in case the weft threads coming from the bobbins 20 and 22 do not interfere with each other.

[0038] Generally, weaving can be possible with both configurations. However, in order to have a reliable control system that regulates the complete insertion process, it is essential that the weft thread type threaded to a particular prewinder 7, 8, 9 is known in the control device 6.

[0039] According to the embodiment shown, the control device 6 is arranged to drive one of the prewinders 7, 8, 9 for drawing off the weft thread fed to said prewinder 7, 8, 9 from the associated bobbin 18, 20, 22 placed on the bobbin rack 14. A movement of the respective weft thread is detected by means of one of the weft thread movement detectors 27, 28, 29. By evaluating the detector signals of the weft thread movement detectors 27, 28, 29, the platform 15, 16, 17 at which the bobbin 18, 20, 22 from which weft thread is drawn off is placed is determined. After the platform 15, 16, 17 is determined, weft thread properties of at least the first bobbin 18, 20, 22 arranged on said platform 15, 16, 17 can be identified by evaluating a sensor signal of the weft thread property identifying sensor 24, 25, 26 provided at the determined platform.

[0040] In the embodiment shown, the weft thread properties identified by the control device 6 are visualized to a user on the human machine interface 33 comprising a display. [0041 ] Figs. 3 and 4 show possible display contents for an arrangement 1 similar to Fig. 1 and 2 comprising four platforms 101 , 102, 103, 104, and four prewinders. 201 , 202, 203, 204,

[0042] Fig. 3 shows a possible display content after bobbins have been placed on the four platforms 101 , 102, 103, 104 and the weft thread properties of bobbins have been identified. The identified weft thread properties of bobbins at the platforms 101 , 102, 103, 104 are indicated in a window 1 A, 2A, 3A, 4A, 1 B, 2B, 3B, 4B associated to a bobbin that is placed on a pin of the platform. The identified weft thread properties are compared by the control device 6 (see Fig. 1 ) to weft thread property information allocated to weft insertion channels in the control device 6. The windows 1A, 2A, 3A, 4A that are associated to the pin on which a bobbin is placed, wherein the identified weft thread properties match with the weft thread property information in the control device 6, are for example marked green. The windows 1 B, 2B, 3B, 4B that are associated to a pin on which no bobbin is placed are for example marked grey.

[0043] Fig. 4 shows a possible display content similar to Fig. 3. In contrast to Fig. 3, a wrong bobbin has been placed at platform 104. The wrong bobbin will be indicated for example by marking the window 4A red, that is shown hatched in Fig. 4. Hereby, starting the weaving process is inhibited. In alternative driving the prewinder 201 , 202, 203, 204 is inhibited, that will be signaled to a user by an arrow 36, for example a white arrow.

[0044] After the weft threads are for example moved one by one, and a movement of the respective weft thread is detected by means of one of the weft thread movement detectors 27, 28, 29, then it is determined which prewinder 201 , 202, 203, 204 is associated to which platform 101 , 102, 103 , 104. In case all identified weft thread properties match with the weft thread property information allocated to weft insertion channels in the control device 6, the correct threading is indicated to the user for example by means of an arrow 34, that is shown hatched in Fig. 3 but in reality is for example a green arrow. In case a weft thread is not yet threaded to a prewinder 201 , 202, 203, 204, this will be signaled to a user by an arrow 35, for example an orange arrow, and starting the weaving process is inhibited. After the threading is correctly completed, a user may start weaving. [0045] Fig. 5 shows another possible display content similar to Fig. 3. In contrast to Fig. 3, a user has threaded the prewinders 203 and 204 with weft thread coming from bobbins of another platform 103, 104 than expected by the control device 6. This mismatch is shown on the display by means of arrows 37, that are shown vertically hatched in Fig. 5 but in reality are for example red arrows. Thereafter, the user in one embodiment has three options:

1 ) exchange the threading of the weft threads coming from the bobbins placed on platforms 103, 104,

2) exchange the positions of the bobbins on the bobbin rack, or

3) adjust the weft insertion channels in the control device 6. [0046] In one embodiment, the adjustment is carried out by the control device 6 after the user has made an input. In another embodiment the adjustment can also take place without further input from the user.

[0047] Figs. 6 shows a possible alternative configuration of the arrangement 1 of Fig. 1 . The configuration of Fig. 6 differs from that shown in Fig. 1 , in that a weft thread coming from a prewinder 9 arranged at the bottom side is threaded to a weft presenter 13 arranged closest to the fabric 4 and a weft thread coming from a prewinder 7 arranged at the top side is threaded to a weft presenter 1 1 arranged furthest from the fabric 4. In the embodiment shown, additional weft thread movement detectors 30, 31 , 32 are provided downstream of the prewinders 7, 8, 9, that are associated to the prewinder 7, 8, 9. Preferably, the weft thread movement detectors 30, 31 , 32 are arranged at the exit of the respective prewinder 7, 8, 9. The additional weft thread movement detectors 30, 31 , 32 allow to determine from which prewinder 7, 8, 9 a weft thread is drawn off by the bringer gripper 2 while a particular weft presenter 1 1 , 12, 13 presents a weft thread to the bringer gripper 2. Hence, the configuration shown in Fig. 6 can be distinguished from the configuration shown in Fig. 1 by the control device 6. Similar to the situation described in the context of Fig. 5, the user in preferred embodiments has several options. In this case, two options are available, namely

1 ) exchange the path of the weft threads or

2) adjust the elements allocated to a weft insertion channel in the control device 6. [0048] Figs. 1 , 2 and 6 schematically show the use of the arrangement 1 in a gripper weaving machine. In alternative, the arrangement 1 may be used in an airjet weaving machine, as shown in Fig.7.

[0049] The arrangement 1 for an airjet weaving machine shown in Fig. 7 is similar to the arrangement of Fig. 1 and for identical or similar elements the same reference numerals are used. In an airjet weaving machine, weft threads are inserted by means of nozzle arrangements comprising main nozzles 41 , 42, 43. Generally, the prewinders 7, 8, 9 are arranged with respect to the main nozzles 41 , 42, 43 acting as second weft insertion channel elements, so that configurations in which the weft thread from a prewinder is threaded to a "wrong" main nozzle are unlikely. Therefore, additional thread movement detectors 30, 31 , 32 (see Fig. 1 ) provided downstream of the prewinders 7, 8, 9 may be omitted. In the embodiment shown in Fig. 7, so called winding detectors 47, 48, 49, that detect the drawing off of windings from a prewinder 7, 8, 9 are provided, which can also be used as weft thread movement detectors. In order to determine from which prewinder a main nozzle draws off weft thread, weft thread can be inserted into a shed.

[0050] In the embodiment of Fig. 7, for each bobbin 18, 20, 22 , 19 ,21 , 23 an associated weft thread property identifying sensor 24, 25, 26, 44, 45, 46 is provided near an associated pin on each platform 15, 16, 17. In an alternative embodiment, only one weft thread property identifying sensor 24, 25, 26, 44, 45, 46 is provided at each platform. [0051 ] The arrangement and the method according to the invention are not limited to the embodiments described by way of example and illustrated in the drawings. Alternatives and combinations of the described and illustrated embodiments that fall under the claims are also possible. All described and illustrated embodiments can be used in gripper weaving machines, airjet weaving machines or other types of weaving machines.