EP1552047A1

EP1552047A1 - Method for holding a weft yarn, and a jet weaving machine, particularly serving to carry out this method

Info

Publication number: EP1552047A1
Application number: EP03750288A
Authority: EP
Inventors: Adnan Wahhoud; Markus Gielen; Dietmar Von Zwehl; Valentin Krumm; Dieter Teufel
Original assignee: Lindauer Dornier GmbH
Current assignee: Lindauer Dornier GmbH
Priority date: 2002-09-18
Filing date: 2003-08-28
Publication date: 2005-07-13
Anticipated expiration: 2023-08-28
Also published as: BR0306435A; EP1552047B1; DE10393812D2; JP2005539161A; AU2003269683A1; WO2004029346A1; DE50306767D1; ATE356237T1

Abstract

The invention relates to a method for holding a weft yarn (9) in the area of a main jet nozzle of a jet weaving machine, particularly an air jet weaving machine, particularly having multicolored pick, before a weft yarn (9) is inserted into a shed (20) formed by warp yarns (10). According to the invention, the weft yarn (9) is clamped in a direction of insertion after an injector (1) in the mixing tube of the main jet nozzle and is released shortly before insertion when a pressure pulse for inserting the weft yarn (9) is initiated by the main jet nozzle. In order to control the corresponding jet weaving machine, a clamping device (6) has a pressure sensor (7) that is connected to a compressed air source (8), a machine control (13), valves (8) and to a compressed air supply (3) of the injector (1) via signal lines (11) and (14) and via compressed air lines (15) and (17). The clamping device (6) is located between a first mixing tube section (4) and a second mixing tube section (5) to which a cutting device (18) is connected. The invention also relates to a method during which the weft yarn section is clamped, whereby holding air is only injected during the time between the capture-side arrival of a weft yarn (9) which was inserted immediately before, and the initiation of the pressure pulse for inserting the next weft yarn, which is required according to the pattern, during a released clamping.

Description

METHOD FOR HOLDING A WIFE AND NOZZLE WEAVING MACHINE,

IN PARTICULAR TO IMPLEMENT THE PROCEDURE

The invention relates to a method for holding a weft thread in the mixing tube of the main nozzle of a jet loom, in particular air jet loom, before the weft thread is inserted into a shed formed by warp threads.

In jet looms known per se, the weft thread to be entered into the shed is fed from a so-called thread store, also referred to as a pre-winder or pre-winder, to a pneumatically acting main nozzle, which represents a weft insertion means with a predetermined length. The main nozzle has an injector and a mixing tube which picks up a weft thread and holds it there until the weft thread enters the shed. The remaining part of the weft thread is located between the main nozzle and the thread store / pre-winder as well as on the thread store / pre-winder itself and is held there until the weft thread is inserted.

In the known air jet weaving machines, the weft thread located in the mixing tube of the main nozzle is kept stretched before its entry with the aid of an air stream which acts in the direction of the longitudinal central axis of the mixing tube. For this purpose, holding air must be blown into the mixing tube in the specified manner during the entire time that the weft thread is held before it is entered into the shed. Compared to the time during which the weft thread is held in the mixing tube of the main nozzle, the actual weft insertion is very short and, depending on the yarn quality, takes place at a pressure of between 1.0 and 6 bar, the pressure of the holding air generally is between 0.1 and 1.5 bar.

Depending on the pattern, several main nozzles are often required for certain tissues. The time during which the weft thread is held in the mixing tube of the main nozzle may be increased by a multiple, depending on the repeat or pattern, compared to the very short weft insertion time.

In order to maintain a thread tension that is as constant as possible, among other things for a high-quality fabric, the pressure of the holding air in the main nozzle compared to normal yarns must be increased further, especially for elastic threads that have a more or less relatively high inherent restoring force, in order to maintain the same constant one To achieve thread tension. However, a higher pressure in the main nozzle / injector usually leads to higher air consumption. WO 00/52 242 describes a device for inserting weft threads for a weaving machine with at least one nozzle, which has an inflow opening for a pressure medium, which is designed in such a way that the pressure medium experiences a rotation about the longitudinal axis of the nozzle, as a result of which a weft or an additional twist is given in the weft thread in the device. The pressure medium, which therefore has a twist, holds the weft thread between the individual wefts for a longer time, in which case excessive rotation should be avoided, since otherwise a fabric of reduced quality would result. In this known air jet weaving machine, the air flow having a swirl in the mixing tube of the main nozzle is therefore exerted on the weft thread essentially for the entire time while it is waiting for its entry into the shed. The disadvantages of holding with holding air described at the outset remain unchanged.

From DE 32 00 638 A1 it is known to hold the weft thread in the mixing tube of the main nozzle of an air jet loom by mechanical clamping. The clamping device required for this is arranged in the region of the outlet end of the mixing tube, in which the weft thread passes into the shed. The clamping device can consist, for example, of a slide which can be displaced transversely to the longitudinal direction of the mixing tube as a lifting element and clamps the weft thread located in the mixing tube between the passage opening of the slide and the inner wall of the mixing tube. Another version provides a transversely displaceable stamp which presses the weft thread against the inner wall of the mixing tube. Finally, a further embodiment of the known mixing device is provided, according to which a partial area of the mixing tube is designed as an elastic intermediate piece. The intermediate piece is to be pressed together by two diametrically opposite lifting members when they are moved against each other. The weft thread is then pinched by the compressed elastic intermediate piece.

In the first and the second embodiment of the clamping device of this air jet weaving machine, the weft thread is displaced laterally when clamping, that is, it is no longer located in the central longitudinal axis of the mixing tube. This phenomenon is also to be feared in the third embodiment, because only two lifting elements are provided for compressing the elastic intermediate piece, so that the compression is not strictly central symmetrical. A position of the weft thread outside the longitudinal center of the mixing tube causes difficulties in the subsequent insertion of the weft thread into the shed. DE 32 00 638 A1 does not explain in detail how the mechanical actuation of the clamping device should be designed in detail. For the slide, the stroke-adjustable punch or the lifting elements for compressing the elastic intermediate piece, a mechanical drive is required in any case, which takes up a certain amount of installation space and, moreover, cannot work without vibration. With regard to this state of the art, the possibility of uncontrolled pivoting movements, which the free end of the mixing tube can carry out when the thread clamp is actuated, is pointed out critically. Since the space available for a larger number of mixing tubes arranged closely next to one another is very limited, in particular in the case of multicolored weft insertion, the known solution cannot readily be implemented in practice. In addition, mechanical vibrations or shocks to the mixing tubes damage the precise function of such jet weaving machines.

WO 02/095106 A1 deals with an air jet weaving machine in which a plurality of main nozzles with the associated mixing tubes are combined to form a compact parallel arrangement. This known air jet weaving machine is thus set up for generating weaving patterns and processing multiple colors. The weft threads in the main nozzle and the mixing tube are held here by clamping action until the weft thread in question is released for entry. The clamping devices are arranged between an auxiliary blowing nozzle and a main blowing nozzle, so they are always located at the entrance of the main nozzles and thus outside the mixing tube. With this arrangement, the position of the weft thread within the mixing tube remains undetermined, so that a central entry of the weft thread into the shed after the release of the weft thread is not guaranteed without further measures. Furthermore, in the air jet loom according to WO 02/095106 A1, the clamping device is also equipped with mechanical clamping members. For this purpose, longitudinally displaceable clamping members designed as pistons or pressure stamps are moved pneumatically. Under the influence of excess pressure, they clamp the associated weft thread against an inner wall of the clamping device, while the resetting of the clamping members and thus the release of the weft threads takes place in that the clamping members are connected to a vacuum source. In this known air jet weaving machine, the devices for holding the different weft threads are thus already assembled very compactly. The clamping of the weft threads at the entrance to the main nozzle and the use of relatively solid mechanical clamping members leads to the disadvantages mentioned above, despite the pneumatic actuation, namely that the position of the weft thread in the mixing tube remains undetermined and mechanical vibrations cannot be excluded. Finally, a method for holding a weft thread at the entrance of a main nozzle is known, in which the weft thread is pressed against the entry of a bypass line by transverse inflow of compressed air before entering the main nozzle (Patent Abstracts of Japan 11200193A of 07/27/99). The weft thread is thus exposed to a longitudinal and a transverse inflow at the same time, which means that the disadvantages of holding weft threads by means of holding air are not eliminated.

In contrast, the invention has for its object to provide a method for holding a weft thread in the mixing tube of the main nozzle of a jet loom, in particular air jet loom, and a jet loom for carrying out the method, with which the amount of holding air required is largely independent of the type and quality of the weft yarns can be significantly reduced or even completely dispensed with holding air, whereby a compact multiple arrangement of main nozzles and mixing tubes is possible, the waste in fabric production is reduced and a negative influence due to holding on the weft yarns is excluded, as well as the overall quality of the fabric produced is increased.

According to the first solution, this object is achieved by the method according to claim 1 and the jet loom, in particular for carrying out this method, according to claim 8. Another solution is specified in the method according to claim 20 and the jet loom, in particular for carrying out this method, according to claim 24. Refinements of these various independent solutions are the subject of related claims.

The first solution according to the invention according to claim 1 thus consists in a method for holding a weft thread in the mixing tube of the main nozzle of a jet loom, in particular air jet loom, before the weft thread is introduced into a shed formed by warp threads, a flexibly designed partial area of the mixing tube being acted upon from the outside by means of a pressure medium is compressed and holds the weft thread clamped.

According to this method, therefore, a purely hydraulic or pneumatic actuation takes place in that a pressure medium compresses the flexibly designed partial area of the mixing tube. The weft is clamped; this type of clamping ensures that the weft yarn is not adversely modified. It has been shown that jamming is not critical in this regard, while holding air modifies the yarns relatively quickly and disadvantageously. The compression of the elastic portion of the Mixing tube by direct exposure to a pressure medium allows very low inertia actuation, the associated facilities can be accommodated in a space-saving manner. In addition, mechanical shocks that could lead to vibrations of the mixing tubes during operation are largely avoided with this type of actuation.

According to an advantageous development, in the method according to the invention the clamping takes place essentially in the region of the outlet end of the mixing tube. With this type of clamping, a largely central arrangement of the weft thread in the mixing tube is ensured even without the application of holding air. This provides favorable conditions for a correct insertion of the weft into the shed when the weft is released for entry.

For further optimization, the method according to the invention advantageously provides that the flexible portion of the mixing tube is deformed so far in the direction of its longitudinal central axis by means of the pressure medium that "the weft thread is clamped in the region of the central longitudinal axis. While, for example, the known one Jet weaving machine according to DE 32 00 638 A1, two diametrically opposed lifting elements are provided, which cannot compress the flexible and elastic sub-area uniformly, but only irregularly and deformingly, with this type of method there is an exactly centrally symmetrical, uniform compression The clamping device thus forms, so to speak, a central lock that aligns the weft in a centrally symmetrical manner and thus the optimal conditions for entry into the shed Affi.

The already very low-inertia actuation according to the method according to the invention is further improved by the fact that, according to a further embodiment, for accelerated release of the clamping and release of the weft thread, the flexible partial region of the mixing tube is placed under negative pressure, controlled from the outside.

Experiments have shown that when the clamping action is released and the weft thread is simultaneously subjected to entry air for the re-entry of a further weft thread into the shed, the elastic partial area of the mixing tube does not relax sufficiently quickly enough, although the entry air flowing into the partial area due to the weft entry the main nozzle supports the relaxation of the partial area. In unfavorable cases, this can lead to the weft thread in the Weft entry still touches the inner wall of the flexible section, leaving traces of wear on it. In the long run, this would reduce the function and service life of the clamping device. With the action of negative pressure when the clamp is released, these possible disadvantages are reliably avoided.

It has proven to be advantageous that the flexible section of the mixing tube is controlled for clamping by means of compressed air at an overpressure of less than 2.0 bar and released by means of compressed air at an underpressure of less than - 50.0 mbar.

As already said, with a clamping in the area of the central longitudinal axis and the outlet end of the mixing tube, the best conditions are given for the

Weft can then be inserted into the shed in the correct position. However, in order to rule out any undesired shifting of the weft thread before it enters the shed and also to achieve its required extension, a short

Transitional period between loosening the clamp and the entry in the shed of the weft can still be temporarily held by the inflowing holding air.

For this purpose, according to an advantageous embodiment of the method according to the invention, it is provided that a certain weft thread is only held with holding air before the entry into the shed when the clamping is open, if it is the next one due to the pattern

Weft thread should be entered.

In particular, it can be provided that the weft thread is held with holding air only between the arrival on the catch side of an immediately previously inserted weft thread and the triggering of the pressure pulse before the entry of the next weft thread.

This embodiment of the method according to the invention is naturally of the greatest importance in the case of multicolored weft insertion. This is because a certain weft thread can have a longer waiting time if the pattern requires it. During the entire waiting time, the weft thread is thus held by clamping alone. Holding air is not required during this time, and the adverse effects of the holding air on the weft threads by modifying them are also eliminated. Only when a weft thread has been inserted immediately and the entry of the relevant held weft thread is imminent is this weft thread briefly held with holding air in order to bring it into the optimal condition for its entry and a position within the mixing tube that is in the correct position. According to the method according to the invention, the weft thread is thus held with a defined clamping force, so that it does not slip out of the main nozzle and nevertheless maintains the optimal position for later entry. With the method according to the invention it is possible to weave types of yarn which previously could not be woven or could not be woven easily with jet weaving machines, in particular air jet weaving machines, even for a high-quality fabric. These include, for example, caterpillars and twisted elastic yarn, which can now be processed relatively easily with the method according to the invention, especially in air jet weaving machines.

The method can be used particularly advantageously when weft threads of different colors are inserted in order to be able to weave certain patterns. An essential advantage of the method according to the invention is that, according to the pattern repeat, the weft thread is clamped depending on the pattern in the case of several main nozzles, which are generally assigned to each color. The weft thread is kept clamped during its entire "waiting time" for the entry until immediately before its entry.

Holding for a short time by means of holding air is only an additional optimization, because with a centrally symmetrical clamping there are already good preconditions for a correct insertion of the weft thread. However, it has been shown that maintaining a constant thread tension is an important criterion for a high-quality fabric and can be achieved particularly well by holding using holding air. The weft thread receives the necessary thread tension and an optimal position in the mixing tube. Because of the only short exposure time of the holding air in the case of the method according to the invention, wherein holding air is only required when the weft thread is imminent, the disadvantageous modification of the weft thread by the holding air is avoided.

The object on which the invention is based is further achieved with a jet weaving machine, in particular for carrying out the method according to one of claims 1 to 7, with at least one main nozzle, comprising an injector with a compressed air connection and a mixing tube connected to the injector, with one in the mixing tube Arranged clamping device, which is formed by a flexible portion of the mixing tube and is used to clamp a weft thread located in the mixing tube to the inner wall of the mixing tube, and with a device for loading the flexible portions of the mixing tube by the pressure medium in such a way that the Partial areas when the pressure medium acts on the weft thread under a certain pressure P. be pressed together and return to their original position when the pressure is released.

As has already been explained in connection with the method, such a construction of the jet weaving machine allows a low-inertia, compact and largely vibration-free function. It is therefore particularly suitable for the creation of weaving patterns with different colors, in which numerous main nozzles with the associated mixing tubes have to be assembled in a compact arrangement. The actuation and control by a hydraulic or pneumatic pressure medium, preferably compressed air, also leads to low-vibration operation, so that the individual mixing tubes with respect to the shed can largely maintain their optimal precise position even in continuous operation.

It is advantageous if the clamping device is a central lock in the form of a pneumatic or hydraulic muscle. In this case, an embodiment is preferred in which the pneumatic or hydraulic muscle clamps the weft thread essentially in the region of the central longitudinal axis of the mixing tube.

The hydraulic or pneumatic muscle comes about because a part of the mixing tube is made of a flexible and highly elastic material. The pressure medium, especially compressed air, acts evenly from the outside and centrally symmetrically on the muscle, so that the greatest possible safety results in a clamping in the area of the central longitudinal axis of the mixing tube.

The pneumatic or hydraulic muscle is arranged between a first and a second mixing tube section and connects the two mixing tube sections in a sealing manner, the pressure medium acting on the muscle in a chamber surrounding it.

An optimal positional holding of the weft thread is achieved in that, according to a further development, the clamping device is arranged on the nozzle opening of the mixing tube.

The pneumatic or hydraulic muscle can be controlled in such a way that the pressure pulse triggered in the injector of the main nozzle for the insertion of the weft thread releases the clamping action of the clamping device. This training is advantageous because the clamping must be removed anyway before the weft thread is inserted into the shed.

It can also be advantageously provided that the chamber can be connected to a negative pressure source in order to quickly relieve the pressure on the pneumatic or hydraulic muscle.

The release of the clamping effect is therefore not simply a result of the fact that the action of excess pressure on the muscle is ended, rather compressed air is simultaneously blown through the inside of the muscle, and the chamber surrounding the muscle can also be exposed to the action of negative pressure.

The connections required for this can be made via solenoid directional valves, and a vacuum pump can serve as a vacuum source.

An advantageous further development consists in the fact that the jet loom according to the invention is provided with a control device which brings about a coordinated interaction in the supply of compressed air from a compressed air source to the injector and the clamping device provided with a pressure sensor, the compressed air serving as pressure medium for the clamping device ,

Such networking of the actuation of the main nozzle and the clamping device leads to a compactly designed and economically working control.

It is further advantageously provided that the clamping device can be held in its open position immediately before the weft thread is inserted and that holding air can only be introduced into the mixing tube via the injector when the clamping device is open.

With this design, the weft thread is held in the by far greatest of its "waiting time" by clamping by means of the pneumatic or hydraulic muscle. The holding air is held only shortly before it is inserted, so that the position and condition of the weft thread optimally matches the entry into the Compared to the state of the art, the risk that the yarns are disadvantageously modified by the holding in is decisively reduced.

After the weft has been inserted into the shed, the weft is separated in the direction of entry by means of a cutting device. That happens at a time in which the pressure pulse triggered by the injector of the main nozzle has dropped again to such an extent that the pressure in the chamber surrounding the muscle predominates and the weft thread is clamped again at the clamping point. The choice of the pressure difference between the pressure pulse of the injector and the pressure in the chamber surrounding the muscle is used to control the opening and closing of the clamping device, depending on the property of the elastic tube piece forming the muscle.

Such a pressure-balanced or pressure-matched system with regard to the maximum pressure of the pressure emitted by the injector of the main nozzle and the pressure of the pressure medium, which compresses the muscle to hold the weft thread, is particularly suitable for particularly rapidly changing cycles, i.e. in this case weaving cycles, for high-speed air jet weaving machines suitable.

Finally, the jet loom according to the invention can be modified in an advantageous manner with such a configuration of the control device that the clamping device can be closed shortly before the end of the insertion of the weft thread so that the weft thread can be braked during this phase of its entry, so that it is braked by the Clamping device slips through. This can be achieved by specifically controlling the pressure difference / the pressure differences between the pressure pulse or the shape of the pressure pulse and the pressure or the pressure curve in the chamber surrounding the clamping device. The clamping device then acts as a brake during a time period shortly before the end of the weft insertion.

With this braking device, depending on the dimensioning of the pressure difference mentioned, thread-saving dissipation of kinetic energy from the weft thread accelerated during the entry to a high speed can be achieved. In this way, the movement of the weft thread (jumping back), which is usually directed towards the stop of the pre-winder at the end of the weft thread, is largely avoided. With such a clamping device, which is optimized with regard to the braking effect and serves as a thread brake, this springing back (loosening) of the weft thread to the stop element can be counteracted, without - as is customary in the prior art - a higher relay nozzle pressure, the use of a stretching nozzle and / or the result is increased lengths of waste. The clamping effect during the gradual braking is controlled via the pressure difference in such a way that the weft thread slips smoothly through the clamping device without being modified itself. It has been shown that the coordination between the pressure or pressure curve in the chamber and the pressure pulse or the shape of the pressure pulse is so fine can be realized that the braking action can be adjusted in an optimized manner depending on the type and quality of the weft thread. This effect occurs without a deterioration in the quality of the tissue. On the contrary, the opposite is the case because the quality of the fabric has been significantly improved compared to an unrestrained entry of the weft thread.

It is also possible that a pre-pulse is triggered by the injector, which is detected by the pressure sensor and serves as a trigger for opening the clamp. The amplitude of the pre-pulse is selected such that it is greater than the pressure in the chamber surrounding the muscle by a defined amount, the duration of the pre-pulse corresponding at least to the duration of the insertion of the protective thread.

According to a further independent proposal for the invention, a method for holding a weft thread in the mixing tube of the main nozzle of a jet loom, in particular air jet loom, is provided before the weft thread is inserted into a shed formed by warp threads, the weft thread being blown with compressed air blown in from the side against the Inner wall of the mixing tube is clamped.

The difference to the first method-related solution is that the compressed air acting no longer effects the clamping via a flexible and elastic section of the mixing tube, but clamps the weft thread directly against the inner wall of the mixing tube.

This design according to the invention allows a particularly simple design procedure. By setting the pressure and quantity of the compressed air flowing in from the side, the desired defined holding force can also be set precisely here.

With this method, it is particularly well possible to carry out the clamping essentially in the region of the outlet end of the mixing tube. It is only necessary to introduce compressed air into the interior of the mixing tube via a lateral opening in the mixing tube. This means a reduction in yarn waste and ensures that only unmodified yarn is present in the actual fabric. This type of clamping can even be realized outside and beyond the mixing tube by a special clamping device.

However, the weft thread is also deflected from the longitudinal center of the mixing tube by the lateral clamping of the weft thread on the inner wall of the mixing tube shifted to the side. An advantageous embodiment of this method according to the invention, in which at least a part of the weft thread is clamped against the inner wall of the mixing tube with compressed air which is blown in from the side, is therefore that the weft thread is held in the mixing tube without compressed air supply with holding air immediately before its entry into the weaving shed or in accordance with Claims 1 to 3 is held clamped in the region of the central longitudinal axis of the mixing tube.

The lateral clamping is thus released immediately before the entry of the weft into the shed, and a return of the weft to the longitudinal center of the mixing tube is achieved by holding with holding air or centrally symmetrical clamping, which ensures optimal conditions for entry into the shed. This is particularly important when filling weft threads of different colors in order to be able to weave certain patterns. The individual weft threads are then clamped depending on the pattern. They are held clamped throughout their "waiting time" for the entry until immediately before the entry. Only after the weft threads have been released are they center-symmetrically clamped or held with holding air if the weft thread in question is to be inserted as the next weft thread, depending on the pattern. During the rest Time, just the waiting time, does not have to be applied to the weft thread with holding air, but only to be laterally clamped in a structurally simple manner, so that holding air is saved or completely avoided, and the harmful effects of the modification do not occur.

In detail, according to a further advantageous embodiment, the procedure will be such that the length of time in which the weft thread is held by holding air or by clamping in the region of the longitudinal central axis of the mixing tube, the time span between the arrival on the catch side of an immediately previously inserted weft thread and the triggering of the Next weft thread entry.

A corresponding jet weaving machine, in particular for carrying out this second method according to the invention, is equipped with at least one main nozzle, comprising an injector with a compressed air connection and a mixing tube adjoining the injector, with a clamping device which can be switched on or off in the mixing tube and through which the weft thread coats Compressed air blown in from the side is clamped against the inner wall of the mixing tube, holding air being introduced into the mixing tube when the clamping device is switched off by means of the injector during the period between the arrival on the catch side of an immediately previously inserted weft thread and triggering a pressure pulse for the entry of the next weft thread, while at I connected clamping device compressed air is introduced laterally in the direction of the inner wall of the mixing tube for clamping the weft in a waiting position.

The advantages of such a jet weaving machine have already become clear from the explanation of the method according to the invention. Of course, the clamping device can be arranged at the end of the mixing tube or even outside of the same, if the structural circumstances so require.

Here, the injector can advantageously be controlled via a controllable valve in such a way that holding air can be admitted only shortly before the entry of the respective weft thread provided for entry.

This configuration serves to save holding air and to avoid the disadvantageous modification of the weft thread by the holding air. Holding air is only introduced into the mixing tube for as short a time as is necessary for an optimal thread tension and a suitable positioning of the weft thread for the entry.

Finally, a lateral compressed air connection and an opening opposite this in the wall of the mixing tube can be advantageously provided on the jet loom according to the invention in such a design that the weft thread is pressed at an angle into the opening during the blowing in of compressed air and at one inside edge of the opening of the mixing tube is held clamped by means of the compressed air.

With the correct design of the opposite opening in the wall of the mixing tube, on the one hand, a very precise and correct holding of the weft thread at the edge of the opening is made possible, but without the risk of modifying or otherwise damaging the weft thread.

Further advantages, features and possible applications of the invention are explained in detail below using an exemplary embodiment based on the attached drawings. The following is shown in the drawings:

Figure 1 shows the basic view of a main nozzle with injector and mixing tube with a clamping device integrated into the mixing tube for clamping a weft thread with a control device, which the clamping of the Matches the weft thread and the triggering of a pressure pulse by the injector;

Figure 2 includes the embodiment of a clamping device in the form of a pneumatic / hydraulic muscle in the open position, i. H. in a position in which the weft thread is not pinched by the muscle;

FIG. 3 shows a pneumatic hydraulic muscle integrated into the mixing tube in the position in which the weft thread is cut off after it has been inserted and is held by the clamping device;

FIG. 4 contains details of a jet loom according to the invention with modified control of the pneumatic / hydraulic muscle, which is shown in its clamped position;

FIG. 5 is a representation corresponding to FIG. 4 when the clamping is released.

Figure 1 shows the basic structure of a main nozzle with injector 1 and mixing tube 2 and in the mixing tube integrated clamping device 6 and the connection of the clamping device 6 with a control device 13, via which a connection between the control of the injector 1 and the control of the clamping device 6 can be realized. A weft thread 9 is arranged in the main nozzle with the injector 1 and the mixing tube 2 and extends essentially along the longitudinal central axis of the mixing tube 2. The clamping device 6, which is shown enlarged in FIGS. 2 and 3, is integrated in the mixing tube 2 between a first mixing tube section 4 and a second mixing tube section 5. At the exit of the weft thread 9 from the second mixing tube section 5, a cutting device 18 is shown in principle. The cutting device 18 is located between the second mixing tube section 5 and the shed 20 shown in plan view, into which the weft thread is to be inserted. The shed 20 is formed by a plurality of warp threads 10.

A pressure sensor 7 is connected to the clamping device 6 and is connected to the control device 13 via a signal line 11. Via further signal lines 14, the control device 13 controls valves 8, which in turn are connected to a compressed air source 19 and a corresponding air supply via a compressed air line 15 to the clamping device 6 or via a further compressed air line 17 enable a compressed air connection 3, which in turn is connected to the injector 1 of the main nozzle and via which the compressed air is supplied to the injector 1 for the supply of holding air and for the insertion of the weft thread 9. The signal lines 14 and 11 control the time dependence between the closing and opening of the clamping device 6 and the triggering of a pressure pulse for the insertion of the weft thread 9 and the beginning and end of the blowing in of holding air.

FIG. 2 shows an enlarged sectional view of the clamping device 6 according to FIG. 1 in the open state. The open state is understood to mean the state in which the clamping device 6 does not clamp the weft thread 9, i. H. releases the weft thread 9 either for entry or during the entry. However, if the weft thread should not yet be inserted due to the pattern, no holding air is blown in, but the weft thread is clamped according to the invention (see FIG. 3).

The weft thread 9 extends through the first mixing tube section 4, through the clamping device 6 and through the second mixing tube section 5 along the central longitudinal axis of the mixing tube. The clamping device 6 connects, so to speak, an airtight mixing tube divided into two by the mixing tube sections 4 and 5. In other words, the clamping device is designed in such a way that in the area of the clamping the wall of the mixing tube 2 is designed so flexibly as a flexible piece of hose that the wall when acted upon by a pressure medium, represented by the arrow in the direction of the inlet into the clamping device 6, is compressed with the pressure P or returns to its original position when the pressure is released. The pressure P _m prevails inside the mixing tube. The flexible wall of the clamping device is designed as a pneumatic or hydraulic muscle 16. This pneumatic or hydraulic muscle 16 is surrounded by the chamber 12, into which the pressure medium with the pressure P is introduced into the clamping device 6 via the compressed air line 15 (FIG. 1). The pressure medium deforms at a correspondingly increased pressure (P> P _m ) the flexible wall of the pneumatic or hydraulic muscle in the direction of the central longitudinal axis of the mixing tube and thus on the weft thread 9. The pressure sensor 7 is connected to the chamber 12, which is connected via the signal line 11 is connected to the control device 13 (see FIG. 1). By means of the pressure sensor 7, through a corresponding control circuit via the valve 8, the controlled supply of the pressure medium from the pressure source 19 takes place or the supply of pressure medium is interrupted, depending on the state of the clamping device 6, ie clamping of the weft thread 9 or releasing the same, depending on the time from triggering a pressure pulse from the injector 1 of the main nozzle to Entering the weft 9 in the shed 20 to get. The compressed air supply to the injector 1 takes place via the compressed air line 17.

Fig. 3 shows the state of the clamping device 6, in which the pressure of the pressure medium P in the chamber 12 is greater than the internal pressure P _m in the mixing tube, so that the flexible wall of the pneumatic or hydraulic muscle 16 in the direction of the central longitudinal axis of the mixing tube 2 is deformed to such an extent that the weft thread 9 is securely clamped centrally so that its thread tension is maintained in the desired manner in the region of the first mixing tube section 4. The section of the weft thread which is separated by means of the cutting device 18 (not shown in FIG. 3) and is located in the second mixing tube section 5 then lies against the inner wall of the second mixing tube section 5 without tension. Since the clamping device 6 with the muscle 16 is relatively close to the interface, that is to say at the front end of the weft thread in the entry direction, and since holding air is largely avoided with the clamping device, i.e. thread modification in the immediate clamping area essentially does not occur, the quality of the Fabric high and waste low. Only the part of the weft thread which is essentially in the first mixing tube section 4 and has an essentially constant thread tension is woven into the finished fabric later, so that otherwise varying thread tensions causing quality differences in the fabric are avoided.

The gas-tight connection between the first mixing tube section 4 and the second mixing tube section 5 is achieved by an annular collar 21 in the form of a union nut in connection with an O-ring seal 22, which is screwed onto the housing of the clamping device 6 in the axial direction, so that the screwing of the ring collar 21 pressed the seal 22 and thus its sealing effect is achieved.

FIGS. 4 and 5 show the modified control of a jet loom designed according to the invention. Those parts which remain unchanged from the previously described embodiment are designated with the same reference numerals as before.

A magnetic directional control valve is used to actuate the pneumatic / hydraulic muscle 16

23, which is controlled by the control device 13 and the pressure lines 24, 26

Chamber 12 of the clamping device 6 connects to an overpressure source 25. The pneumatic / hydraulic muscle 16, that is to say the flexible and highly elastic, is thereby formed Part of the mixing tube, compressed symmetrically and evenly in the direction of the longitudinal central axis of the mixing tube 2 and clamps the weft 9.

To cancel the clamping action, the solenoid directional control valve 23 is reversed and thereby connects the chamber 12, the pressure line 26 and the connection instruction 27 to a vacuum source 28. This results in a rapid pressure relief of the pneumatic / hydraulic muscle 16. The acceleration of the release process leads to the fact that the weft thread 9, which then immediately starts to move, can no longer drag along the flexible and highly elastic wall of the muscle 16. Damage to the muscle 16 is thereby avoided even after a long period of operation.

Claims

claims

1. A method for holding a weft thread in the mixing tube of the main nozzle of a jet loom, in particular air jet loom, before the weft thread is introduced into a shed formed by warp threads, a flexibly designed partial area of the mixing tube being pressed together by external pressure by means of a pressure medium and the weft thread holds tight.

2. The method according to claim 1, wherein the clamping takes place essentially in the region of the outlet end of the mixing tube.

3. The method of claim 1 or 2, wherein the flexible portion of the mixing tube is deformed in the direction of its central longitudinal axis by means of the pressure medium so far that the weft thread is clamped in the region of the central longitudinal axis.

4. The method according to any one of claims 1 to 3, in which the flexible portion of the mixing tube is placed under negative pressure controlled from outside to accelerate the clamping and release of the weft.

5. The method of claim 4, wherein the flexible portion of the mixing tube is controlled by means of compressed air at an overpressure of less than 2.0 bar for clamping and released by means of compressed air at an underpressure of less than -50.0 mbar.

6. The method according to any one of the preceding claims, in particular with multi-colored weft insertion, in which a particular weft thread is only held with hold air before the entry in the shed when the clamping is open when it is to be entered as the next weft thread due to the pattern.

7. The method according to claim 6, wherein the weft thread is held only between the catch-side arrival of an immediately previously entered weft thread and triggering the pressure pulse for the entry of the next weft thread with holding air.

8. jet loom, in particular for performing the method according to one of the

Claims 1 to 7, with at least one main nozzle, comprising an injector (1) with a compressed air connection (3) and a mixing tube (2) adjoining the injector (1), with a clamping device (6) arranged in the mixing tube (2), which is formed by a flexible portion of the mixing tube (2) and is used to clamp a weft thread in the mixing tube to the inner wall of the mixing tube, and with a device for applying pressure to the flexible portion of the mixing tube in such a way that the Partial area when pressurized by the pressure medium under a certain pressure P, the weft thread is pressed together and returns to its original position when the pressure is released.

9. jet loom according to claim 8, wherein the clamping device (6)

Central locking is in the form of a pneumatic or hydraulic muscle.

10. jet weaving machine according to claim 9, wherein the pneumatic or hydraulic muscle clamps the weft thread substantially in the region of the central longitudinal axis of the mixing tube (2).

11. jet weaving machine according to claim 8 or 9, wherein the pneumatic or hydraulic muscle between a first mixing tube section (4) and a second mixing tube section (5) is arranged and the two mixing tube sections

(4,5) sealingly connects, the pressure medium acting on the muscle in a chamber (12) surrounding it.

12. Jet loom according to one of claims 8 to 11, wherein the clamping device (6) is arranged at the outlet opening of the mixing tube (2).

13. jet loom according to one of claims 8 to 12 in such a configuration that the pressure pulse triggered in the injector (1) of the main nozzle for the insertion of the weft thread (9) releases the clamping action of the clamping device (6).

14. jet weaving machine according to one of claims 11 to 13, in which the chamber (12) can be connected to a vacuum source (28) for rapid pressure relief of the pneumatic or hydraulic muscle.

15. jet loom according to claim 14, wherein the connection via a solenoid directional valve (23) takes place.

16. jet loom according to claim 14 or 15 with a vacuum pump as a vacuum source (28).

17. jet loom according to one of claims 8 to 16, with a control device (13) for coordinated interaction in the supply of compressed air from a compressed air source (19) to the injector (1) and the clamping device (6) provided with a pressure sensor (7) , wherein the compressed air serves as a pressure medium for the clamping device (6).

18. jet weaving machine according to claim 17 with such a configuration of the control device (13) that the clamping device (6) is stable in its open position immediately before the entry of the weft thread (9) and holding air in only when the clamping device is open via the injector (1) the mixing tube (2) can be introduced.

19. jet loom according to claim 17 or 18 with such a configuration of the control device (13) that the clamping device (6) shortly before the end of the entry of the weft thread (9) can be closed so far that the weft thread (9) during this phase of its Entry can be braked so that it slows down through the clamping device (6).

20. A method for holding a weft thread in the mixing tube of the main nozzle of a jet loom, in particular air jet loom, before the weft thread is introduced into a shed formed by warp threads, the weft thread being clamped against the inner wall of the mixing tube with compressed air blown in from the side.

21. The method according to claim 20, wherein the clamping takes place essentially in the region of the outlet end of the mixing tube.

22. The method according to claim 20 or 21, in which at least part of the weft thread is clamped with laterally blown compressed air against the inner wall of the mixing tube, but immediately before the entry of the weft thread into the shed of this in the mixing tube without compressed air supply with holding air or according to the claims 1 to 3 is held in the region of the central longitudinal axis of the mixing tube.

23. The method according to claim 22, in which the time period in which the weft thread is held by holding air or by clamping in the region of the longitudinal central axis of the mixing tube is the time span between the arrival on the catch side of a weft thread that was entered immediately before and the triggering of the entry of the next weft thread ,

24. jet weaving machine, in particular for carrying out the method according to one of claims 20 to 23, with a main nozzle, comprising an injector with a compressed air connection and a mixing tube adjoining the injector, with a clamping device arranged in or off the mixing tube, through which the Weft thread with compressed air blown in from the side against the inner wall of the

Mixing tube is clamped, with the clamping device switched off by means of the injector during the period between the arrival on the catch side of an immediately previously entered weft thread and triggering a pressure pulse for the entry of the next weft thread, holding air is introduced into the mixing tube, while with the clamping device switched on, compressed air is directed laterally towards the inner wall of the Mixing tube for clamping the weft thread is initiated in a waiting position.

25. jet weaving machine according to claim 24, wherein the injector can be controlled via a controllable valve such that holding air only shortly before the entry of the respective

Entry of the intended weft thread can be taken.

26. Jet loom according to claim 24 or 25, with a lateral compressed air connection and an opening opposite this in the wall of the mixing tube in such a configuration that the weft thread during the

Blowing in compressed air with its end angled pressed into the opening and held clamped by means of the compressed air on an edge of the opening running around the inside of the mixing tube.