EP1584719A1 - Monitoring the transport of yarn - Google Patents

Abstract

In a process to monitor the advance of a thread in a weaving loom, the thread has a series of notional sections (21) that advance at a suitable speed (v(i). In the process, a value (24) is determined of a kinematic measuring value relating to the thread notional section (21). The value (24) is used in an algorithm (2) to determine the tensile force on the thread that determines the thread approach speed (25). The approach speed is presented on a display. The calculation is made either for a point on the thread or for a section of thread. The process is further employed as a simulation using finite element analysis. Further claimed is a commensurate weaving loom.

Description

The invention relates to a method for monitoring the transport of a Thread, in particular the entry of a weft thread in one Loom according to the preamble of claim 1, and a loom equipped to carry out such a method.

As part of the general process optimization and automation in the Textile technology is the detection and monitoring of the current dynamic process variables that characterize the yarn transport are of great importance. Under dynamic Process variables are understood in the following primarily as quantities, which cause a movement of the thread, i. acting on the thread Forces. In current weaving machines, for example, the Warp tension is detected and used to control the warp let-off drive used. In contrast, in current weaving machines, the detection of the on a weft thread pulling forces usually only in the context of experimental projects. This restriction is largely due to the Fact attributed to the thread for detecting the thread tension must be deflected to a force acting on a measuring cell normal force to create. If no existing diversion is used can, an additional deflection is required, the thread transport ever can hinder massively after deflection. This is especially true for Weaving machines with air entry systems. Analogously, there are in Textile machinery a variety of situations where direct detection the desired dynamic, characteristic for the thread transport Process size difficulties or with greater effort connected is. This is for example for measurements over longer transport sections or in hard to reach places or for the measurement of Thread transport occurring thread tensile forces that were not contactless could be recorded.

The object of the invention is a method for monitoring the transport a thread, in particular the entry of a weft thread in one Weaving machine to provide, by which method Approximate values of at least one dynamic, for the thread transport characteristic process size can be determined. Especially The method is intended to approximate one in a thread point or be determined on a thread portion acting yarn tension, and in particular, the required quantities are required be detectable without contact. Another object of the invention is to provide a Loom to provide, for the execution of such Method is equipped.

This object is achieved by the defined in claim 1 Method, and solved by the defined in claim 10 loom.

In the inventive method for monitoring the transport of a Thread, in particular the entry of a weft thread in one Weaving machine, the thread comprises thread points or sections, respectively be transported at an associated speed, and it will be Values of at least one measured value dependent on the thread transport detected at least one thread point or portion, for example Values of a kinematic measurand such as the above Speed. In the inventive method are due to the captured values by means of a calculation model approximate values at least a dynamic process variable which is characteristic of the yarn transport, For example, approximate values of the thread tension, for at least one Thread point or section calculates and the calculated approximations evaluated to monitor the yarn transport, the calculated Approximate values are displayed in particular and / or for controlling the Thread transport can be used.

The calculation model used to calculate the approximate values is preferably designed as a simulation model for the yarn transport, especially as a simulation model according to the finite element method. Conveniently, the calculation model or the Simulation model model parameters, where in a preferred Variant at least a part of the values recorded as Control variables used for iterative adaptation of model parameters becomes.

Preferably, the thread is transported substantially straight and Preferably, the calculation model or the simulation model formed one-dimensionally. Advantageously, the thread is for example as one-dimensional continuum oscillator or one-dimensional Vibration chain modeled. Also, the use of simple empirical Calculation models is possible.

In an advantageous embodiment of the method is by means of Simulation model over a transport period, the temporal change of Approximate values of at least one dynamic, for the thread transport characteristic process variable for at least one thread point or calculated section and in a further advantageous embodiment by means of the simulation model over at least a partial length of the thread the local change in the approximate values of at least one dynamic, calculated for the thread transport characteristic process size.

In a preferred embodiment of the method Approximate for in at least one thread point or on calculated thread tensile force acting at least one thread section, wherein in a preferred embodiment over the entry period of a Weft a set of approximations for in at least one Thread point or acting on at least one thread section Fadenzugkraft be calculated.

In a further preferred embodiment of the method, the Values of at least one thread-dependent measurement, preferably a kinematic measurement, detected without contact.

Preferably, values of one of the following measured variables are recorded: Start time in a given position, time of arrival in a given time Position, shift after a certain period of time or Speed. In a weaving machine, the weft is usually from withdrawn from a drum-shaped thread storage device. Preferably In this case, the removal of a weft thread section by means of a so-called Windungszählers recorded to from the corresponding Windungszählersignalen the start time and / or the withdrawal speed of the weft thread section.

Furthermore, the invention comprises a textile machine, in particular a Weaving machine equipped to carry out one of the above Method.

The inventive method has the advantage that for monitoring the thread transport in a textile machine and in particular in a Weaving machine due to comparatively fewer measured values Approximate values for a variety of dynamic and kinematic Process variables can be calculated for the yarn transport are characteristic. In particular, it is possible the readings detect contactless, so disturbing effects on the Fadentransport be avoided. This is the first time, for example possible when entering a weft thread in a loom Approximate values for the thread tension forces acting on the weft thread determine without contact. The means of the inventive Method calculated approximate values, for example, to Monitoring of the thread transport are displayed, whereby e.g. the Adjustment of the thread transport is facilitated, or trigger an alarm, if a given limit value of the relevant process variable is exceeded, or also used to control the yarn transport become. The calculation of the approximate values can be done periodically, which e.g. for adjustment purposes is enough. But it is also possible to take readings at least one measured variable dependent on the thread transport to capture quasi-continuously and calculate the approximate values at least one process variable characteristic of the yarn transport immediately afterwards, so that quasi-instantaneous " Approximate values are available for monitoring the yarn transport stand.

Further advantageous embodiments are the dependent Claims and the drawings.

Fig. 1

eine schematische Darstellung eines Ausführungsbeispiels zum Verfahren gemäss vorliegender Erfindung,

Fig. 2

eine Ausführungsvariante einer Zelle eines Rechenmodells zur Verwendung in dem in Fig. 1 gezeigten Ausführungsbeispiel,

Fig. 3

eine modellmässige Darstellung einer Ausführungsvariante des Fadentransports zu dem in Fig. 1 gezeigten Ausführungsbeispiel,

Fig. 4

zwei aufeinanderfolgende Zellen der in Fig. 3 gezeigten Ausführungsvariante, und

Fig. 5

eine schematische Darstellung der Parameteranpassung zu dem in Fig. 1 gezeigten Ausführungsbeispiel.

In the following the invention will be explained in more detail with reference to the embodiment and with reference to the drawing. Show it:

Fig. 1

a schematic representation of an embodiment of the method according to the present invention,

Fig. 2

an embodiment variant of a cell of a computer model for use in the embodiment shown in Figure 1,

Fig. 3

a model representation of a variant of the yarn transport to the embodiment shown in Figure 1,

Fig. 4

two successive cells of the embodiment shown in Fig. 3, and

Fig. 5

a schematic representation of the parameter adjustment to the embodiment shown in Fig. 1.

Fig. 1 shows a schematic representation of an embodiment of a method according to the present invention. In the exemplary embodiment, the entry of a weft thread in an air-jet loom is monitored. Of course, the method according to the invention is also suitable for monitoring the yarn transport in other weaving machines or in other technical fields. The weft thread of the embodiment comprises thread points or sections which are each transported at an associated speed v _i . Reference numeral 1 in FIG. 1 summarizes the acquisition of values 24.1-24.n of at least one measured variable dependent on the thread transport for at least one thread point or section. Reference numeral 1 also includes the sensors used to acquire the values 24.1-24.n and the hardware necessary for the preparation and evaluation of the corresponding measurement signals. Typically, values of at least one kinematic parameter are detected, such as the start time in a predetermined position, the time of arrival in a predetermined position, the shift after a certain period of time or the speed. In a preferred embodiment, the values 24.1-24.n are detected without contact. For example, by detecting the passage of the weft thread when removing a drum-shaped yarn store by means of a so-called Windungszählers and from the corresponding signals of the Windungszählers the start time and / or the withdrawal speed of the respective weft thread section are determined, or by the speed by means of optical correlation or spatial filter method with electrostatic Signal generation according to DE 199 00 581 A1 is detected. Further, the arrival time of the weft thread can be detected without contact in a predetermined position, in particular at the end of the weft insertion, for example by means of a weft thread guard.

The detected values 24.1-24.n are in the exemplary embodiment on Calculation model 2 transmitted, for example, the values in a Memory to which the computer model 2 has access. On Reason of the detected values are calculated by means of the calculation model 2 Approximate 25.1-25.n 'at least one dynamic, for the Thread transport characteristic process size for at least one Thread point or section calculated, e.g. in at least one Thread point or acting on at least one thread section Yarn tension. The used calculation model 2 will be described below in Frame of the description of Figures 2 to 5 explained in more detail. Under the Reference numeral 2 also falls within the physical implementation of Computational model, in particular a computing unit and a data and a program memory in which the calculation model is stored is. Advantageously, the arithmetic unit and the data and the Program memory in a control of the thread transport and / or in a Machine control unit, for example in a control unit of Weaving machine, integrated or implemented.

In an advantageous embodiment, over a transport period, for example, during the duration of the weft insertion, by means of Simulation model the temporal change of the approximate values 25.1-25.n ' at least one dynamic, characteristic for the thread transport Process size calculated for at least one thread point or section. In a further advantageous embodiment variant is by means of Simulation model over at least a partial length of the thread, the local Change of approximate values 25.1-25.n 'of at least one dynamic, is calculated for the thread transport characteristic process size.

The calculated approximate values 25.1-25.n 'are used in the exemplary embodiment transmitted to an evaluation unit 3, for example, a Display function or device, an alarm function or device or control functions for controlling the Fadentransports and / or other machine parts includes. In the Evaluation unit 3, the calculated approximate values 25.1-25.n ' evaluated for monitoring the yarn transport, in particular displayed and / or to control the yarn transport or other Machine functions used.

The calculation model 2 used for the calculation of the approximate values is advantageously designed as a simulation model for yarn transport, for example as a simulation model according to the finite element method. Advantageously, the thread is transported in a substantially straight line, so that a one-dimensional calculation model or simulation model can be used. The restriction to a straightforward Fadentransport deviates strongly from the reality, since the thread during the Transport, if possible, vibrations in all degrees of freedom or in all degrees of freedom is deflected. An exact one However, analytical description of the thread movement in space is usually not feasible, since the required influencing variables hardly with the necessary accuracy can be detected. Transport routes with simple Reversals of the thread direction can be contrast, often with a approximate one-dimensional simulation model by using the Deflections e.g. be considered as brake components in the model. Advantageously, the thread is, for example, as a one-dimensional Continuum oscillator or modeled as a one-dimensional oscillation chain. The use of simple empirical calculation models is possible, too No special requirements for the accuracy of the calculated Approximate values are made.

In a preferred embodiment of the calculation model or simulation model, the thread is treated as a one-dimensional vibration chain, ie as a vibration body with a number of cells or thread sections. FIG. 2 shows an embodiment variant of a cell of such a computer model. The cell 21 or the corresponding thread section has a mass m _i , a constant of elasticity k _i , and a damping c _i . Furthermore, an external force F _i (x, t) acts on the cell 21, which can be both position-dependent and time-dependent. Examples of such an external force are the driving force of an air nozzle in an air entrainment system, the effect of which depends on the distance between the cell and the nozzle, or the braking force of a yarn brake in the transport path. Normally, the driving force of an air nozzle is not detected directly, but at least approximate values for the driving force can be determined on the basis of known values for air pressure and blowing time and due to the distance between the cell and the nozzle.

FIG. 3 shows a model representation of a variant of the yarn transport to the embodiment shown in FIG. In this embodiment, it is the entry of a weft thread in an air jet loom. The illustration shows the weft thread at two different times t _k and t _N during or at the end of the weft insertion. The weft thread comprises thread sections 21.i, 21.i + 1, 21.N, which decompose the free thread length into a maximum of N cells. It should be noted that in this embodiment, the number of cells used in the calculation during the weft insertion continuously increases until at the end of the weft insertion at the time t _N, the maximum number of N cells is reached. The numbering of the cells was chosen in the present embodiment variant such that the cell newly added in the calculation receives the number 1, while the numbers of the previous cells are increased by one. In this way, the number of cells belonging to the weft tip continuously increases during the weft insertion until it reaches the value N. By means of the air nozzles 31, 32, 33.1 - 33.m shown in FIG. 3, the weft thread is accelerated in a known manner. Typical nozzle arrangements include, for example, a main nozzle 31, a tandem nozzle 32, and a series of relay nozzles 33.1-33.m.

F_ki =

auf die i-te Zelle wirkende Fadenzugkraft

F_ci =

auf die i-te Zelle wirkende Dämpfungskraft

F_i =

auf die i-te Zelle wirkende Resultierende der äusseren Kräfte

F_mi =

auf die i-te Zelle wirkende Trägheitskraft

F_ki+1 =

auf die i+1-te Zelle wirkende Fadenzugkraft

F_ci+1 =

auf die i+1-te Zelle wirkende Dämpfungskraft

wobei dFki/dt = ki · (vi-1 - vi) Fmi = mi · dvi/dt Fci = ci · (vi-1 - vi) mit

k_i =

Elastizitätskonstante der i-ten Zelle

v_i =

Geschwindigkeit der i-ten Zelle

v_i-i =

Geschwindigkeit der (i-1)-ten Zelle

m_i =

Masse der i-ten Zelle

c_i =

Dämpfung der i-ten Zelle

Fig. 4 shows a variant of two successive cells 21.i, 21.i + 1 in detail. The cells are each transported at a speed v _i , v _{i + 1} . The cells 21.i, 21.i + 1 have model parameters 22.i, 22.i + 1, for example a mass m _i , m _{i + 1} , a elastic constant k _i , k _{i + 1} and an attenuation c _i , C _{i + 1} on. Normally, it is sufficient to assume the model parameters mentioned over a calculation period as constant in time and space, so that in this case no mass balances have to be taken into account. By contrast, it may be expedient to take into account the dependence of individual model parameters on dynamic or kinematic process variables. For example, the elasticity constant depends on the yarn tension, the course being normally asymmetric, or the damping on the speed v _i , v _{i + 1} . In each case act on the cells 21.i, 21.i + 1 external forces whose resultant is referred to in Fig. 4 with F _i and F _{i + 1,} and may vary in time and / or locally. Examples of such external forces are the driving force of an air nozzle in an air entrainment system, the effect of which depends on the distance between the cell and the nozzle and the duty cycle, or the time-varying braking force of a yarn brake in the transport path. For the i-th cell 21.i the following balance of forces applies: F ki + F ci = F i + F Wed. + F ki + 1 + F ci + 1 With

F _ki =

Yarn tension acting on the i-th cell

F _ci =

damping force acting on the i-th cell

F _i =

Resultant of the external forces acting on the i-th cell

F _mi =

inertial force acting on the i-th cell

F _{ki + 1} =

Yarn tension acting on the i + 1-th cell

F _{ci + 1} =

on the i + 1-th cell acting damping force

in which dF ki / dt = k i · (V i-1 - v i ) F Wed. = m i · Dv i / dt F ci = c i · (V i-1 - v i ) With

k _i =

Elasticity constant of the i-th cell

v _i =

Speed of the ith cell

v _ii =

Speed of the (i-1) th cell

m _i =

Mass of the ith cell

c _i =

Attenuation of the i-th cell

The cells 21.i, 21.i + 1 can, as shown schematically in Fig. 3, to a complete calculation model for the thread transport. The The maximum number N of cells depends on the desired spatial and temporal resolution of the model. Advantageously, the thread transport assumed to be rectilinear and / or the calculation model one-dimensional educated.

The calculation model described above allows the calculation of a vibration body with N cells. That is, by solving the differential equations given, approximate values for all the dynamic and kinematic variables occurring in the model over a desired transport period can be calculated, in particular the yarn tension acting on a cell or on a thread section. The necessary model parameters 22.i, 22.i + 1 can optionally be determined separately or with the aid of the model, for example by using a part of the acquired values as control variables for the iterative adaptation of the model parameters. Model parameters such as the mass m _{i of} a cell or a thread section can be determined without difficulty separately by weighing, as long as the mass over the length of the thread is sufficiently constant. By contrast, model parameters such as the damping c _{i of} a cell can only be determined separately with greater effort, in particular if the damping varies over the length of the thread. Advantageously, model parameters such as attenuation are determined by computation.

5 shows a schematic illustration of an embodiment variant of the calculation model for iterative parameter adaptation and / or optimization. An overall model 2 comprising a mathematical model 20, for example a mathematical model as explained in the description of FIG. 4, is supplied with values 24.1-24.n of at least one measured variable dependent on the yarn transport, for example values v _{i of} the yarn take-off speed, eg quasi-continuous can be determined from turn counter signals, and the arrival time t _{N of} the weft at the end of the weft insertion. The supplied values can be used once or continuously, in particular iteratively, to adapt or optimize individual model parameters by varying the relevant model parameters in such a way that the difference Δv _i , Δt _N between the detected values v _i , t _N and corresponding calculated values v and _i , t and _N becomes minimal. At the same time, each calculation cycle yields approximate values 25.1-25.n 'for desired dynamic or kinematic process variables which are characteristic of the yarn transport, for example approximation values for the yarn tension acting in a yarn section.

The inventive method for monitoring the yarn transport has the advantage that from easy-to-read values at least one The thread-dependent measured variable by means of a computer model Approximate values for the thread transport of characteristic process variables can be calculated, which otherwise only with greater effort or with Difficulties are to be determined. That's the way it is for example possible, approximate values for those acting in a thread section Determine thread tension without contact. The calculated approximations are then evaluated to monitor the yarn transport, for example, by displaying the approximate values or controlling the Thread transport can be used. In an advantageous embodiment the calculation and / or evaluation of the approximate values in a controller the yarn transport and / or in a machine control unit, for example in a control unit of the weaving machine, integrated or implemented.

Claims (10)

Method for monitoring the transport of a thread, in particular the entry of a weft thread in a loom, in which method the thread comprises thread points or sections (21, 21.i) which are each transported at an associated speed, Values (24.1-24.n) of at least one measured variable dependent on the thread transport, in particular a kinematic measured variable, of at least one thread point or section (21, 21.i) are detected, characterized in that on the basis of the detected values (24.1-24.n) by means of a calculation model (2) approximate values (25.1-25.n ') of at least one dynamic process variable characteristic of the yarn transport for at least one yarn point or section (21, 21.i) be calculated, and the calculated approximate values (25.1-25.n ') are evaluated for monitoring the yarn transport, in particular displayed and / or used to control the yarn transport. The method of claim 1, wherein the calculation model (2) as Simulation model is designed for the yarn transport, in particular as a simulation model according to the finite element method. Method according to one of claims 1 or 2, wherein the Calculation model (2) or the simulation model Contains model parameters (22.i), and wherein at least a part of the recorded values (24.1-24.n) as control quantities for iterative Adaptation of model parameters (22.i) is used. Method according to one of claims 2 or 3, wherein by means of Simulation model over a transport period, the temporal Change of approximate values (25.1-25.n ') of at least one dynamic, characteristic for the thread transport process size for at least one thread point or section (21, 21.i) is calculated becomes. Method according to one of claims 2 to 4, wherein by means of Simulation model over at least a partial length of the thread local change of approximate values (25.1-25.n ') of at least one dynamic, characteristic for the thread transport process size is calculated. Method according to one of claims 1 to 5, wherein approximate values (25.1-25.n ') for in at least one thread point or on at least one thread section (21, 21.i) acting yarn tension and in particular over the entry period of a weft thread a series of approximate values (25.1-25.n ') for in at least one thread point or at least one Thread section (21, 21.i) acting yarn tension is calculated. Method according to one of claims 1 to 6, wherein approximate values a size dependent on the yarn tension, in particular Approximate values of the thread tension or thread elongation, calculated or evaluated. Method according to one of claims 1 to 7, wherein the values (24.1-24.n) at least one measured variable dependent on the thread transport be detected without contact, and / or where values (24.1-24.n) a the following metrics are recorded: start time in one predetermined position, arrival time in a predetermined position, Shift after a certain period of time or speed. Method according to one of claims 1 to 8, wherein the thread in the Essentially transported in a straight line and / or the calculation model (2) or the simulation model is formed one-dimensionally is. Weaving machine equipped to carry out a method according to one of claims 1 to 9.

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