JP2006144217A - Method for braking weft of loom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method (1) for braking the weft (2) of a loom (3), especially a jet loom (3). <P>SOLUTION: This method for braking the weft (2) of the loom (3), comprising bringing a braking element (4) into contact with the weft (2) and operating the braking element (4) with a driving device (6) through a controller (5), is characterized by determining the first measurement value (8) of the operation parameter (9) of the weft (2) during the insertion (7) of the weft, estimating the first measurement value (10) of the operation parameter (9) on the basis of the first measurement value (8), determining a correction value (11) therefrom, and then correcting the operation parameter (9) of the weft (2) on the basis of the correction value (11). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for braking a weft of a loom and to a loom for carrying out the method.

  It is known to use so-called ABS brakes on jet looms, in particular air jet looms, for controlled braking of the weft. In this specification, ABS represents an automatic weft braking device. The goal of this case is in particular to avoid excessive weft stresses caused in particular by sudden braking of the weft thread, for example by means of a stop pin of the thread store. The ABS brake is realized, for example, in the form of a movable hoop with at least one deflection point for deflecting the yarn. The braking force is affected by the weft deflection caused by the braking hoop. The hoop is primarily journaled in a freely rotatable manner and is in active contact with a drive device such as a magnetic coil or an electric motor, and the drive device transmits signals for control and / or adjustment to an appropriate control system. Connected.

  In the present application, the measurement of the physical movement parameters of the weft thread, such as the measurement value of the thread tension or the thread tension of the weft thread, is measured directly by a sensor such as a pressure sensor, for example, or the speed of the weft thread, for example It can be understood to mean an indirect measurement of the motion parameter, which is a derived parameter. By way of example, the speed of the weft can only be measured indirectly by measuring the path change of the weft within the periodic exchange. References to measurement below refer to both direct and indirect measurements.

  In an air jet loom according to EP 0548185, a control device is disclosed that calculates parameters to control the weft braking of a current weft insertion based on at least one or more previous weft insertion data. . That is, the average value of the motion parameter is determined over one or more weft insertions, and from there, for example, for weft braking, an adjustment parameter for the weft motion parameter is determined for subsequent weft insertion.

  The disadvantages of this method are obvious. This means that one or more weft insertions must always be performed before the controller can adapt the parameters for subsequent weft insertions, so the response time of the system to changes is compared at the weft insertion boundary conditions. Long. Also, it cannot act immediately on short-term disturbances, that is, disturbances that occur individually during a specific weft insertion. This is because only the average value over a plurality of weft insertions can be considered. For example, if the control device calculates a third weft insertion parameter based on two weft insertions, then two weft insertions are required before the control device can respond to the change. This dead time in the response of the control device, as already mentioned, is very disadvantageous especially in the case of sudden disturbances.

  The object of the present invention is therefore to propose an improved method of weft insertion which avoids the features known from the prior art so as to further optimize the weft insertion of the jet loom.

  The subject matter of the invention which satisfies this object with respect to the method and the apparatus is characterized by the features of the independent claims 1 and 10. The dependent claims relate to particularly advantageous embodiments of the invention.

  Thus, according to the invention, a method is provided for braking the weft of a loom, in particular a jet loom, in which the braking element contacts the weft and the braking element is actuated by a drive device via a control device. In this arrangement, during the insertion of the weft, a first measured value of the weft motion parameter is determined, a first estimated value of the motion parameter is estimated based on the first measured value, and a correction value is determined therefrom. Next, the movement parameter of the weft is corrected based on the correction value.

  Therefore, according to the present invention, the correction value for correcting the motion parameter is determined as follows. That is, at the first time, a movement parameter such as the speed of the weft is measured. From this measurement, a predicted value, for example an estimated value of the speed of the weft, can be extrapolated to a specific point in time after which the movement parameter should be corrected by the braking of the thread, and therefore the movement parameter at a subsequent second time point. Correction parameters can be estimated.

  With this arrangement, the present invention clearly clearly relates to a method for braking the weft of a jet loom, but in principle is not limited to a jet loom. Rather, the present invention relates to a method that can be equally advantageously carried out in a similar manner on other looms such as, for example, rapier or projectile looms.

  The correction of the movement parameter, for example the speed, ie the instantaneous speed of the weft, by means of the braking of the thread is carried out in a manner known from the prior art, where specific dynamic parameters of the weft, such as the weft thread tension or Speed is measured over multiple weft insertions, and then from the data thus obtained, correction parameters are calculated by forming an appropriate average value, with the aid of which movement parameters such as weft speed are then In addition, there is an influence during continuous weft insertion by weft braking.

  In the prior art, the reason for relying on the average value formed from multiple previous weft insertions to influence continuous weft insertions is actually measured at any point in time, as previously mentioned This is because, as a result of the measurement, it is not possible to influence the weft movement appropriately at the same time, for example via the braking of the thread. This is due to the very high speed of inserting the weft thread in the operating state. For example, when operating a loom at a rotational speed of 1000 rpm, the instantaneous speed of the weft can easily reach several hundred meters per second.

  This means that if, for example, the speed of the yarn is measured at a particular point in time, the measured value must be evaluated accordingly and a correction value must be determined from the measured value of the measurement. Can be applied to the yarn with appropriate control. Therefore, from the moment when the instantaneous value of the movement parameter, such as the instantaneous velocity of the weft, is measured, to the point when the correction of the movement parameter is the earliest possible as a result of this measurement, the result of the inertia of the entire arrangement, the weft There is always a slight amount of time compared to the higher speeds.

  For example, when measuring the speed or tone of the weft yarn at the first time point, the measurement can determine whether the motion parameter at this time point corresponds to or deviates from a specific desired value. If the measurement determines that there is a specific deviation, in principle, the method of controlling the braking of the thread so that the movement parameter of the thread is adjusted to the desired value at the time of the measurement as a result of the magnitude of the deviation. Can be easily determined. However, as a result of the very high instantaneous speed of the weft and the inevitable inertia of the adjustment system, the correction of the motion parameters cannot be performed until a time after the measurement time.

  As a result, at a later point in time when the braking of the yarn acts on the weft movement parameter earliest and correctively, the movement parameter actually has a different value for a longer time than the measurement point, and thus the weft obtained from the measurement. The correction values for correcting the motion parameters are no longer used. Therefore, the prior art relied on average correction values determined from a specific number of previous wefts.

  The present invention avoids the disadvantages resulting from using the average value to determine the correction value. This is because according to the present invention, a correction value at a subsequent time point is estimated from the estimated value of the motion parameter based on the first measurement value, and the correction value is corrected from the estimated value to correct the motion parameter at a certain time point after the measurement. This is because it becomes possible to determine this. The advantages of the method according to the invention are obvious. There is no longer any need to average the correction parameter from the average value of the number of wefts passing through, so in order to correct the movement parameter of the weft, a short period of time while the loom is in motion or while the weft is inserted into the saddle Take fluctuations into account.

  In a preferred exemplary embodiment of the method according to the invention, determining the first measured value of the weft kinematic parameter, as a result of the estimation, the kinematic parameter acts as a corrective action on the weft yarn by subsequent braking of the yarn. Estimating the first estimated value, determining the correction value, and correcting the movement parameter of the weft yarn at a subsequent time is performed during one and the same weft insertion. This ensures that the correction of the motion parameters for each weft insertion is performed from here, ie as a result of the data determined from the instantaneous weft insertion.

  As already mentioned, the movement parameters used for optimal weft insertion monitoring and control and / or adjustment are, for example, the position or speed of the weft thread, preferably the instantaneous speed, the acceleration of the weft thread, the force, the mechanical tension, the thread tension. Or another motion parameter.

  In fact, in a particularly important example, the weft is braked in such a way that the weft movement parameters, in particular the weft speed, reach a value within a predetermined tolerance range at the end of the braking process. This is particularly important to avoid the final “whipping effect” or stopper strike of the weft insertion, which is well known to experts. This occurs immediately before the weft is completely inserted into the saddle, and therefore just before the weft reaches the draw nozzle, for example when the weft brake is too sudden or too fast, for example by a thread stopper. Therefore, it is very important that the speed of the weft yarn is within a clear optimum tolerance range just before reaching the draw nozzle.

  If a particularly high requirement is given for the insertion of the weft, for example in the case of very thin fabrics and / or high-quality fabrics, especially if the weft is very long and the mass inertia of the yarn is large, after the first measurement The second measured value is measured during the insertion of the weft, the second estimated value is estimated based on at least the second measured value, and the movement parameter of the weft is newly influenced based on the second measured value. That is, in the same weft insertion process, it is possible to measure, estimate, and correct the motion parameter multiple times, so insertion of the weft into the tunnel is a predetermined ideal course of motion parameter. Which can be presented or created as a reference file, for example in the form of a look-up table, or in another suitable manner.

  In other words, the correction values for influencing the movement parameters are defined as follows: a predetermined desired profile for each estimator and a predetermined desired profile for the course of the instantaneous velocity of the weft thread during the insertion into the tunnel, for example. It can be formed by comparing the number of times or by comparing the number of times continuously.

  In another exemplary embodiment, the second measurement value is measured during insertion of the weft thread after the first measurement value, and at least one first estimate value is estimated based on the first measurement value and the second measurement value. The weft movement parameter is influenced based on at least the first estimated value. Thus, for example, the first measured value may be a determination of the position of the weft yarn at a specific first time point, and the second measured value may be related to the determination of the position of the weft yarn at the second time point. The position of the weft yarn at a subsequent third time point can then be estimated through linear interpolation from these two position measurements, and as a result of this estimation, the weft movement parameters, eg position and / or velocity, are Correction can be made at the third time point.

  Of course, at more than two different time points, more than two position measurements and / or velocity measurements and / or measurements of other movement parameters of more than two wefts are carried out and from these measurements, for example from the secondary It is possible to estimate the weft kinematic parameters at a later point in time through interpolation with a high polynomial or another mathematical function, or otherwise. Thus, for example, it is advantageous to supplement an estimate of the yarn speed at a subsequent time from at least three measurements of the motion parameters at a previous time.

  In this situation, it is preferred that the motion parameter can also be measured without contacting the sensor. For example, the speed of the weft can be measured in particular with an optical sensor.

  However, other movement parameters of the weft can of course also be measured in order to determine the correction value. Thus, in special cases, it is possible to provide a sensor element in contact with the weft, so that, for example, an instantaneous yarn force or tension of the weft can be detected during weft insertion.

  The present invention further monitors a jet loom having a braking element that can contact the weft, the brake element being operable by a drive, and a sensor and / or sensor element provided for measuring a weft kinematic parameter, and There is a control device provided with a correction unit. The control device is connected to the driving device of the braking element in a signal transmission manner and is connected to the sensor and / or sensor element in a signal transmission manner to determine the motion parameter. Therefore, during the insertion of the weft, the first measured value of the weft motion parameter can be read into the correction unit and the first estimated value of the motion parameter can be estimated based on the first measured value. From here, the correction value can be determined by the correction unit, and the movement parameter of the weft can be corrected by the braking element based on the correction value.

  The invention is explained in more detail below with reference to the drawings.

  FIG. 1 shows a cross-sectional view of an exemplary embodiment of a jet loom 3 according to the invention, which in this case is an air jet loom 3 and includes a braking element 4 having a drive 6 and a control unit 5. The air jet weaving machine 3 further comprises a yarn ribbon 15, a braking element 4, an auxiliary nozzle 17 and a main nozzle from which a suitable length of weft 2 is wound around a drum store 16 in a manner known per se. 18, the weft 2 comes from the drum store 16 in operation, is guided on the braking element 4, accelerated in the two nozzles 17 and 18, and conveyed along the reed 19 through the saddle . Details of the weft insertion in the jet loom 3 are known per se and therefore do not need to be explained in further detail. For example, an air jet loom 3, which is known per se, is not known for the sake of clarity.

  The exemplary embodiment shown in FIG. 1 of the jet loom 3 according to the invention has at least one optical sensor 14 in the drum store 16 so that, for example, the instantaneous position 9 of the weft 2 or the instantaneous speed of the weft 2 9 is measured while pulling the weft 2 in operation from the drum store 16 in a manner known per se. In this situation, the instantaneous speed 9, which is a motion parameter in this example, can be determined more accurately as the number of optical sensors 14 provided in the drum store 16 increases. Thus, for example, two, three, four or more optical sensors 14 can be provided in the drum store 16 so that the instantaneous speed 9 of the weft 2 can be measured or calculated with the desired accuracy. It is preferable that it can be uniformly distributed over the circumference of the store 16.

  In FIG. 2, a diagram of the movement parameters / time of the weft 2 is schematically shown. In this example, as the thread tension F acts in the weft 2 during the insertion of the weft, it is plotted on the ordinate as a function of time t, the time t has elapsed during the weft insertion of the weft 2 and the abscissa Is plotted in In this plot, the solid line shows the course of the thread tension F, which here is a motion parameter 9 depending on the weft insertion time t as known according to the prior art weft insertion procedure. The broken line shows the corresponding time dependence of the yarn force F for the weft insertion performed according to the method according to the invention.

  Weft insertion starts at time t1. That is, at time t1, the weft 2 is released from the drum store 16 through the withdrawal of the stopper pin. Next, the yarn force F changes only slightly during the first weft insertion phase between time t1 and the subsequent time t2. During this first stage, the weft 2 is initially not affected by the braking element 4. That is, at the first weft insertion stage, the weft 2 is not braked at first. The braking phase starts at time t2 when the weft 2 is already fully inserted into the saddle. That is, after that time t2, the braking element 4 acts on the weft 2 in a braking state, and at time t3, the stopper pin in the drum store 16 finally prohibits further withdrawal of the weft 2.

  As already mentioned, the solid line in FIG. 2 shows the time dependence of the thread tension F of the weft 2 for the weft 2 braking method known from the prior art. Prominent is the so-called “whipping effect”, which results in a weave 2 of the weft yarn 2 that occurs dramatically during the braking phase between times t2 and t3, which is in the solid curve between times t2 and t3. It is expressed impressively with remarkable local maximum points. It is clear that a considerable change in this kind of thread tension F acts very negatively on such weft insertion and therefore negatively affects the quality of the fabric. In the worst case, the weft 2 may be destroyed.

  One reason why the thread tension F behaves in this way in the weft 2 braking method known in the prior art is that the thread tension F is used as a motion parameter 9 for determining the correction value 11 and based on it. This is because the braking element 4 is controlled to brake the weft 2. That is, for example, it is incorporated in the braking element 4 or measured with a force measuring device which can determine the thread tension force F as a separate force measuring device as measured, for example, from the contact pressure of the weft 2 against the force measuring device. The resulting thread tension F is averaged over a plurality of previous weft insertions, from which a correction value 11 is formed, on which the braking element 4 is controlled and / or adjusted to brake the weft 2.

  In this situation, in order to appropriately determine the correction value 11 so as to brake the weft thread 2, it has been proved that the thread tension F is a rather inappropriate parameter. One reason for this can be seen in the known way that the use of a yarn force sensor obstructs the passage of the yarn due to deflection. On the other hand, the thread tension F is an inappropriate parameter because the mass of the yarn section to be braked during the weft insertion naturally increases continuously. This is because the length of the inserted weft thread 2 continuously increases during insertion into the tunnel. Therefore, it is almost meaningless to adjust only the thread tension F to a predetermined level. Preferably, for example, the final speed of the weft 2 is achieved within a predetermined tolerance range under boundary conditions where the weft insertion time is maintained. It has proved much better to adjust the final weft speed in such a way. However, to do so, the weft braking must be adjusted as a result of the data derived from the weft insertion itself to be adjusted, not from the average value of the previous weft insertion, which naturally does not take into account the current irregularities. This in particular leads to the “whipping effect” shown in FIG. 2 with negative results as is known.

  The dashed line in FIG. 2 shows a plot of the time dependence of the thread tension F for the weft insertion performed according to the one according to the invention. In the first stage, the thread tension F behaves like a known braking method between time points t1 and t2. This is because the weft 2 is not yet braked at this stage. After time t2, the weft 2 is braked according to the method 1 according to the invention, as will be explained in more detail below with respect to FIG.

  The positive effect of using the method 1 according to the invention on the thread tension F during the braking phase between times t2 and t3 can be clearly recognized with reference to the dashed line. The variation of the thread tension F is clearly attenuated. In other words, the “whipping effect” that occurs in the methods known in the prior art is practically completely suppressed. This greatly improves the weft insertion of the weft, which ultimately protects the weft 2 and improves the quality of the fabric or increases the performance, respectively.

  A further improvement is that, according to the method 1 according to the invention as illustrated by way of example in FIG. 2, the thread tension F is not used to determine the correction value used for the weft insertion, as shown in FIG. The jet loom 3 is used. That is, the instantaneous speed 9 of the weft 2b is calculated and determined from the measurement position 9 of the weft 2 for determining the correction value 11 without contacting the optical sensor 14, for example.

  At this point, it should be noted that in almost all cases it is preferable to measure the movement parameter 9 of the weft 2 without contact. The measurement with the sensor 14 in contact with the weft 2 is because the movement of the weft is already negatively affected only by the contact. It has also proven to be most preferable to select the instantaneous speed 9 as the movement parameter 9 in almost all cases.

  However, it must be clearly stated that the method 1 according to the invention is not limited to non-contact measurements. Rather, in special cases, it may be preferable to operate with another sensor, which measures the thread tension F, for example, in a contact manner.

  In FIG. 3, a speed / time diagram of a plot of the instantaneous speed 9 of the weft yarn 2 during the braking phase between time points t2 and t3 is shown with the weft yarn 2 being braked according to the method 1 according to the invention. The movement parameter 9 is plotted on the ordinate, which in this case is the instantaneous speed of the weft 2 and the time t is plotted on the abscissa. Braking of the weft 2 by the braking element 4 starts at time t2. At a time Tm between the time t2 and the time t3, the instantaneous speed 9 of the weft 2 is measured by, for example, the optical sensor 14 in a state where t3 marks the end of the braking phase. Based on this measurement, a first estimated value 10 of the movement parameter 9 is determined, which in this case means that the instantaneous speed 9 of the weft 2 at a subsequent time point TR is estimated and a correction value 11 is formed therefrom. It is. Based on the correction value 11, the motion parameter 9, which is the weft speed 9 here, is corrected at a subsequent time point TR. In this situation, the correction value 11 is determined such that the speed 9 of the weft 2 has a value within the tolerance range 2 at the end of the braking process before the stopper pin stops further insertion of the weft 2 at time t3. It is preferable.

  In order to correct the speed 9 of the weft 2 during one identical weft insertion, it is possible to determine whether the instantaneous speed 9 of the weft 2 is measured several times, so that the updated correction value 11 is a new estimate in each case It is obvious that the speed 9 of the weft 2 is adapted several times, determined from the value 10.

1 is an exemplary embodiment of a jet loom according to the present invention. It is a kinematic parameter / time chart of a weft. FIG. 3 is a diagram according to FIG. 2 as a weft speed / time diagram;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Method 2 Weft 3 Loom 4 Braking element 5 Yarn bobbin 6 Driving device 7 Weft insertion 8 First measured value 9 Motion parameter 10 First estimated value 11 Correction value 12 Tolerance range 14 Optical sensor 16 Drum store 17 Auxiliary nozzle 18 Main nozzle 19 Lead 51 Correction unit

Claims (11)

  In this method, the weft (2) of the loom (3), in particular the jet loom (3), is braked. The brake element (4) comes into contact with the weft (2), and the brake element (4) passes through the control device (5). The first measured value (8) of the movement parameter (9) of the weft (2) is determined during the insertion (7) of the weft and the first measured value (8). ) To estimate the first estimated value (10) of the motion parameter (9), determine the correction value (11) therefrom, and based on the correction value (11) the motion parameter of the weft (2) ( 9) is corrected.   Determination of the first measured value (8) of the motion parameter (9) of the weft (2), estimation of the first estimated value (10), determination of the correction value (11), and motion parameter (9) of the weft (2) The method according to claim 1, wherein the correction is performed during one and the same weft insertion (7).   The movement parameter (9) of the weft (2) is the position (9), speed (9), acceleration (9), force (9), mechanical tension (9), thread tension (9) of the weft (2) or The method according to claim 1, wherein the at least one movement parameter is a movement parameter.   In such a way that the movement parameter (9) of the weft (2), in particular the speed (9) of the weft (2), achieves a value which is within a predetermined tolerance range (12) at the end of the braking process. The method according to any one of claims 1 to 3, wherein:   The second measured value (8) is measured after the first measured value (8) during the weft insertion (7), and the second estimated value (10) is estimated based on at least the second measured value (8). The method according to any one of claims 1 to 4, wherein the movement parameter (9) of the weft (2) is also influenced on the basis of the second estimated value (10).   The second measured value (8) is measured after the first measured value (8) during the weft insertion (7), and at least one first estimated value (10) is measured with the first measured value (8) and the second measured value. 6. The estimation according to claim 1, wherein the movement parameter (9) of the weft (2) is influenced based on at least the first estimation value (10). The method according to item.   7. The correction value (11) affecting the movement parameter (9) is formed through a comparison of the estimated value (10) and a predetermined desired profile of the movement parameter (9). 2. The method according to item 1.   The method according to any one of the preceding claims, wherein the movement parameter (9) is measured without contact with the sensor (14).   9. The method according to claim 1, wherein the position (9) and / or speed (9) of the weft (2) is measured, in particular by means of an optical sensor (14).   9. The method according to claim 1, further comprising providing a sensor element in contact with the weft (2).   A braking element (4) that can contact the weft (2), the braking element (4) being operable by a drive device, and a sensor (14) and / or for measuring the movement parameter (9) of the weft (2) Or a loom provided with a sensor element, provided with a control device (5) having a correction unit (51), the control device (5) being connected to the drive device (6) of the braking element (4) in a signal transmission manner. Connect and connect the sensor (14) and / or sensor element in a signal transmission manner to determine the motion parameter (9) and, during the weft insertion (7), the motion parameter (9) of the weft (2) The first measured value (8) can be read into the correction unit (51), and the first estimated value (10) of the motion parameter (9) can be estimated based on the first measured value (8). To the correction value by the correction unit (51) 11) is capable of determining, loom motion parameter of the weft thread (2) by the braking element on the basis of the correction value (11) (4) (9) is characterized in that it is correct.

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