EP1270781A1 - Method and device for controlling the warp let-off on a loom - Google Patents

Abstract

In a process to regulate a weaving loom warp let-off motion, a target rotational speed (SD) is set for a warp beam by determining the warp thread (3) tension (K). The warp thread tension is allocated a weight function (G) to establish a warp thread weighting (KG). A corrected warp beam rotational speed (SDK) is derived from the SD and KG. The warp beam speed is corrected by reference to SDK. The corrected target speed SDK is the sum of the target speed SD and warp thread weighting KG. The weighting factor G includes one factor alpha by which the thread tension is multiplied. The warp thread (3) tension is varied by a change in the value of SD and/ or G especially alpha. Also claimed is a commensurate assembly with a thread (3) tensiometer (5), a warp beam (3) rotational speed sensor (7), a regulator (1) linked to the tensiometer (5) and sensor (7) and a warp beam drive motor.

Description

The invention relates to a method for controlling the warp let-off Loom according to the preamble of claim 1. The invention relates further an apparatus for performing the method according to the Preamble of claim 10.

The document US 4,942,908 discloses a control device for a Weaving machine which influences the warp thread tension The speed of the warp beam changed accordingly. This control device is operated in two fundamentally different operating modes. In a first operating mode specifies a fixed speed, with which the warp beam is rotated, regardless of the warp thread tension. In a second operation mode, the voltage of the sensor Warp threads measured, and the speed of the warp beam regulated so that the tension of the warp threads corresponds to a predetermined value. This known control device allows to influence the tissue density, by changing the tension of the warp threads accordingly. The Tension of the warp threads influences the way they are incorporated into the forming tissue, and thus also influences the tissue density. The kind of Tension control of the warp threads is therefore central to a To produce fabrics of consistent, reproducible quality.

A disadvantage of the known regulation is the fact that the manufactured Fabric is of reduced quality, for example if the Quality of the woven yarn, for example the modulus of elasticity, Is subject to fluctuations, or if different weaves be woven.

It is an object of the present invention a method for controlling the Propose a warp loom to a weaving machine, which is a higher one Fabric quality allowed.

This object is achieved with a method having the features of Claim 1. The sub-claims 2 to 9 relate to further advantageous Process steps. The object is further achieved with a device having the features of claim 10.

The object is achieved in particular with a method for controlling the warp let-off of a weaving machine, in that a desired speed S _{D is} specified for a warp beam, by determining a warp tension K of the warp threads emitted by the warp beam, by weighting the warp tension K with a weighting function G and a weighted warp tension K _{G is} determined in such a way that a corrected desired speed S _{DK is} determined from the values of the desired speed S _D and the weighted warp tension K _G , and by the speed of the warp beam as a function of the corrected desired speed S _DK is controlled.

An advantage of the method according to the invention can be seen in the fact that no weaving phases occur during which the warp tension does not is defined. The warp let-off of the weaving machine or the speed of the warp beam is both from a predetermined target speed and determined by the measured warp tension of the warp threads.

In an advantageous embodiment, the warp tension with a Weighting function weighted, the weighting factor being adjustable, so that it can be determined to what extent the warp tension Speed of the warp beam should affect. The inventive The method is usually operated in such a way that the speed of the Kettbaums both from the specified target speed and from measured warp tension depends.

By an appropriate choice of the value of the weighting factor however, the following two special cases occur.

If the weighting factor is set to zero, the warp tension acts no longer depends on the speed of the warp beam. The speed is thereby determined only by the specified target speed. Such Control of the warp let-off is also called a "positive warp feed system" or referred to as a "positive system". This positive system will preferably set such that a constant warp thread length per Weaving cycle is delivered regardless of those occurring in the warp threads Voltage values.

If the weighting factor is set to infinity, the value of the specified target speed no longer depends on the speed of the warp beam. The speed is determined solely by the warp tension. A such control of the warp let off is also called a "negative Warp feed system "or referred to as a" negative system ". This negative system has the property that the warp threads are delivered in this way be that the tension of the warp threads a predetermined value having. The warp thread length delivered per weaving cycle is therefore dependent on the tension of the warp threads.

A control device for the negative system can be constructed in such a way that that the warp tension is measured and using in a warp tension regulator a setpoint is compared. The warp tension regulator forms as Output signal a target speed, which a subordinate Speed controller is fed to match the speed of the warp beam to control the target speed.

A regulation according to the positive system has the disadvantage that the warp thread tension is subject to large fluctuations, for example caused by varying yarn quality and / or varying Fabric binding, so that the manufactured with this control method Tissue can have an adverse tissue image.

Regulation according to the negative system also has the disadvantage that a tissue with an adverse tissue image is produced, for example caused by varying yarn properties and / or varying weave.

This is a major advantage of the method according to the invention see that the chain incorporation is subject to slight fluctuations. Under chain incorporation is understood as the quotient of consumed Warp thread length and fabric length produced. The chain incorporation hangs among other things from the warp thread tension or from the Warp beam from the warp thread length. As a rule, when weaving quantitative relationship between warp incorporation and warp tension not known, which has the consequence that with a regulation according to negative system the target value for the warp tension to a certain Achieve chain incorporation can not be specified precisely. together with the running properties of the weaving process, which include warp tension and so that the chain incorporation determines, the chain incorporation is also by influences article-specific factors such as weft density or binding. Therefore, despite precise control of the warp tension, there is no guarantee that that the fabric produced has the necessary warp incorporation, or that the fabric has good dimensional stability or a uniform fabric weight.

The method according to the invention allows both regulation of the Warp let off according to a positive as well as a negative system. Of However, it is of central importance that the method according to the invention is a Regulation in a mixed form of positive system and negative system allowed. The proportions of the positive system and the negative Systems at the control procedure can also use the values of Weighting function G can be set.

The method according to the invention enables a fabric of higher quality manufacture, in particular a fabric with a balanced Warp incorporation, that means a fabric with a uniform Fabric weight.

In an advantageous development of the method according to the invention both the warp thread length given by the warp beam and the generated tissue length measured to one from this data Chain incorporation value to be determined. In another, advantageous The weighting function is dependent on the method Warp work value changed so that a fabric with a predetermined target chain incorporation value is produced.

Fig. 1

ein erstes Ausführungsbeispiel einer Regelvorrichtung;

Fig. 2

eine erste Kennlinie, welche den Zusammenhang zwischen Kettspannung und korrigierter Soll-Drehzahl darstellt;

Fig. 3

ein zweites Ausführungsbeispiel einer Regelvorrichtung;

Fig. 4

eine zweite Kennlinie mit korrigierter Soll-Drehzahl;

Fig. 5

eine dritte Kennlinie mit korrigierter Soll-Drehzahl;

Fig. 6

schematisch eine Webmaschine mit Warenbaum.

The invention is described below using several exemplary embodiments. Show it:

Fig. 1

a first embodiment of a control device;

Fig. 2

a first characteristic curve, which represents the relationship between warp tension and corrected target speed;

Fig. 3

a second embodiment of a control device;

Fig. 4

a second characteristic curve with corrected target speed;

Fig. 5

a third characteristic curve with corrected target speed;

Fig. 6

schematically a weaving machine with goods tree.

FIG. 1 shows a warp beam 2 which is driven by a motor 4 and feeds warp threads 3 to the weaving machine. The actual speed I _{D of} the warp beam 2 is detected by a sensor 7. The warp tension K of the warp threads 3 is detected by a sensor 5. The control device 1 detects the warp tension K, weights it in a transmission element 6 with a weighting function G, and passes the weighted warp tension K _{G to} an adder. By adding a corrected target speed S _{DK is} calculated from a predetermined target speed S _D and the weighted warp tension K _G. This corrected target speed S _DK serves as a reference variable for a subordinate control loop. Advantageously, the speed control device 8 of the lower-level control loop is designed as a PID controller, so that the error signal F of the lower-level control loop tends towards zero, thereby controlling the speed of the warp beam 2 via the motor 4 and the speed sensor 7 such that the speed of the warp beam 2 im essentially corresponds to the corrected target speed S _DK .

The value of the weighting function G can be set manually in the transmission element 6 can be entered. However, it can also prove to be advantageous Value of the weighting function G electrical, for example via a line 11 to feed the transmission member 6.

6 schematically shows a weaving machine with a warp beam 2 with warp threads 3 driven by a motor 4, and with a warp beam 12 with fabric 13 driven by a motor 14. The speed of the warp beam 2 and the warp beam 12 of FIG of the higher-level control device 16. In addition, this detects the warp tension K with a tension sensor 5. The higher-level control device 16 generates, for example in dependence on the diameter of the warp thread winding located on the warp beam 2, a corresponding desired rotational speed S _D for the warp beam 2. This desired rotational speed S _D becomes fed to the control device 1.

The method according to the invention for controlling the warp let-off now takes place in such a way that the warp beam 2 is given a target speed S _D by the higher-level control device 16, that the warp tension K of the warp threads 3 emitted by the warp beam 2 is measured such that the warp tension K has a weighting function G is weighted and a weighted warp tension K _{G is} determined in such a way that a corrected desired speed S _{DK is} determined from the values of the desired speed S _D and the weighted warp tension K _G and that the warp beam 2 with the corrected desired speed S _{DK is} controlled.

FIG. 2 shows in a first characteristic curve K1 a linear relationship between the warp tension K and the corrected target speed S _DK . The formula G = α (K - Ko) applies to the weighting function G. The factor α of the weighting function determines the slope of the characteristic curve K1. The factor Ko is chosen such that the target speed S _D , as shown in FIG. 2, comes to lie at a preferred warp tension Ko. The control of the warp let-off with the first characteristic curve K1 shown in FIG. 2 proceeds as follows: As long as the warp tension K maintains the value Ko, the value of the corrected desired speed S _DK corresponds to the value of the desired speed S _D. As soon as the warp tension K rises, the value of the corrected set speed S _{DK also increases} according to the course of the first characteristic curve K ₁ , so that the warp beam 2, as shown in point K ₁₃ , corrected with a higher speed than the set speed S _D Target speed S _{DK is} operated. In this area designated V _E , the corrected set speed S _{DK has} a higher value than the set speed S _D , which is also referred to as leading V _E. As soon as the warp tension K falls below the value Ko, the value of the corrected desired speed S _DK decreases in accordance with the course of the first characteristic curve K ₁ , so that the warp beam 2, as shown in point K ₁₄ , has a speed opposite the desired speed S _D reduced corrected target speed S _{DK is} operated. In this area designated N _E , the corrected set speed S _{DK has} a lower value than the set speed S _D , which is also referred to as lagging N _E. The behavior shown in Figure 2 gives the control of the warp let a stable behavior. If, for example, an increase in the warp tension K occurs due to a change in the warp thread properties, the corrected desired rotational speed S _DK and thereby also the rotational speed of the warp beam 2 are increased accordingly, so that the warp tension K is reduced again, and the control system becomes one new working point stabilized.

The control characteristic of the method according to the invention can be influenced by several measures. The value of the target speed S _D can be increased or reduced, regardless of the value of the warp tension, in order to change the control characteristic. In addition, it is common for the setpoint speed S _{D to be changed} by the higher-level control device 16 during the operation of the weaving machine, for example depending on the amount of warp threads 3 located on the warp beam 2.

The control characteristic can also be changed by changing the weighting function G. For example, the factor α can be increased / decreased so that the curve K _{1 has} a larger / smaller gradient α. A value that is too high for the factor α essentially leads to a negative warp feed system in that the warp tension K is regulated independently of the target speed S _D. A value that is too small for the factor α essentially leads to a positive warp feed system in that the corrected desired rotational speed S _DK is essentially independent of the warp tension K. The warp let control according to the invention thus combines the properties of the positive and the negative warp feed system. The optimal value for the factor α depends on various aspects, such as weaving conditions, yarn properties or weave. The factor α is preferably set for a particular article to be woven. For example, a weaving process can be started by initially setting a large value for the factor α. The effect on the fabric created is observed, the chain incorporation is measured, and then the factor α is possibly changed again until the optimal setting for this factor is found. For yarns with a high modulus of elasticity, the factor α should have a small value, since otherwise small changes in the warp tension would cause a large change in the warp feed. Accordingly, a factor α with a large value is advantageous for yarns with a low modulus of elasticity.

The weighting function G can be defined in a large number of possible functions. In order to influence warp tension changes dynamically, it can prove to be advantageous to also define the weighting function G as a function of time. Such a weighting function could, for example, be defined as G = α (1- e ^{- bt} ). The weighted warp tension K _G is therefore dependent on the time t, in addition to the value of the warp tension K and the value of the factor α, due to the exponential function as a function of time t.

In addition to the control device according to FIG. 1, the second exemplary embodiment of a control device 1 shown in FIG. 3 also has a threshold switch 9 and two electrical changeover switches 10a, 10b which are actuated by the relay 10. The warp tension K is fed to the threshold switch 9, which compares the value of the warp tension K with a lower warp tension K _SU and an upper warp tension K _SO . As long as the value of the warp tension K lies between the values K _SO and K _SU , the electrical changeover switches 10a, 10b assume the position shown in FIG. As soon as the value of the warp tension K is greater or less than the values K _SO or K _SU , the threshold switch 9 generates a switching signal which actuates the electrical switching device 10 and changes the position of the electrical changeover switches 10a, 10b. The first changeover switch 10a thereby feeds a target warp tension S _{K to} the electrical line 17. The second changeover switch 10b separates the value of the target speed S _D from the control device 1. As a result, the control device 1 operates as a pure warp tension controller in that the control warping device 1 is given the desired warp tension S _K. It should be noted that the value of the target warp tension S _{K must be} above or below the value K _SO , K _SU .

A warning can also be triggered when the threshold switch 9 is triggered triggered to notify a supervisor. The Threshold switch 9 can have a manual input Man to the threshold switch 9 again in that shown in Fig. 3 Reset operating mode.

The control device 1 according to the invention is also suitable for operating a weaving machine with a first and a second warp beam 2. Each of the two warp beams 2 is driven by its own motor 4, the arrangement shown in FIG. 1 with control device 1 and sensors 5, 7 for controlling the motor 4 being provided for each warp beam 2. FIG. 4 shows the characteristic curve K _{1 of} the first control device ₁ used for the first warp beam 2. The characteristic curve K ₁ has a slope α1. FIG. 5 shows the characteristic curve K _{2 of} the second control device 1 used for the second warp beam 2. This characteristic curve K ₂ can have a different gradient α ₂ . These different pitches α ₁ , α ₂ are particularly advantageous if the warp threads 3 of the individual warp beams 2 have different textile properties, such as a different elasticity. Advantageously, one of the warp beams 2 is selected as the master system and the other warp beam 2 as the slave system, the set speed S _D of which is specified by the master system. In the exemplary embodiment shown, the first warp beam 2 is operated as a master system in accordance with the characteristic curve K ₁ shown in FIG. 4, whereas the second warp beam 2 is operated as a slave system in accordance with the characteristic curve K ₂ shown in FIG. As already described with FIG. 2, the first warp beam 2 is operated in such a way that a target speed S _{D is} specified, which gives the point K ₁₁ on the characteristic curve K ₁ . On the basis of the warp tension of the warp threads emitted by the first warp beam 2, the control device 1 uses point K _{22 to} generate the corrected desired speed S _DK at which the first warp beam 2 is rotated. This corrected target speed S _DK is given to the slave system, which controls the second warp beam 2, as the target speed S _D. The warp tension of the second warp beam 2 can change independently of the first warp beam 2. The control device 1 of the second warp beam 2, as shown in FIG. 5, generates the corrected target speed S _DK with which the second warp beam 2 is rotated on the basis of the measured warp tension and taking into account the characteristic curve K ₂ . The result of this type of control is that the two warp beams 2, which have warp threads with different properties, can have different warp tension values and different speeds. This regulation with a master system and a slave system enables uniform warping, even with warp threads with different properties.

Figure 8 shows part of a fabric 13 consisting of warp threads 3 and weft threads 18. The fabric 13 has a 1/1 weave. For this weave, the warp incorporation C is defined as C = L 1 - L 2 / L 2, the incorporated warp thread length being denoted by L1 and the fabric length produced being denoted by L2.

FIG. 7 shows a control device 19, to which the measured value for the incorporated warp thread length L1 and the measured value for the fabric length L2 are fed, so that the control device 19, as shown, is capable of the current value of the warp incorporation C as the actual Chain incorporation (C _IST ). This value is compared with a predetermined desired Ketteinarbeitung (C _SOLL) by taking the difference of these two values is formed, and this difference signal is supplied to a PI controller 20th This controller 20 generates a signal for correcting the specification of the factor α in the weighting function G, which is fed to the transmission element 6 via the line 11, as shown in FIG. 1, for example. The fabric length L2 generated can be determined, for example, with the aid of the sensor 15, which measures the speed of the fabric tree 2.

It can prove advantageous to use the voltage sensor 5 and / or smooth the measured values of the speed sensor 7, or to form an average of the measured values, before these values are sent to a subordinate unit.

The method according to the invention for regulating the warp let-off is for Different types of weaving machines are suitable, for example for Projectile looms, air jet looms, Multi-phase weaving machines or rapier weaving machines.

Claims (10)

Method for regulating the warp let-off of a weaving machine by specifying a target speed (S _D ) for a warp beam (2), by determining a warp tension (K) of the warp threads (3) emitted by the warp beam (2) by the warp tension ( K) weighted with a weighting function (G) and a weighted warp tension (K _G ) is determined in this way by using the values of the desired speed (S _D ) and the weighted warp tension (K _G ) to correct a desired speed (S _DK ) is determined and by controlling the speed of the warp beam (2) as a function of the corrected target speed (S _DK ). A method according to claim 1, characterized in that the added values of target speed (S _D ) and weighted warp tension (K _G ) result in the corrected target speed (S _DK ). Method according to one of the preceding claims, characterized in that the weighting function (G) has only a factor α by which the warp tension (K) is multiplied. Method according to one of the preceding claims, characterized in that the tension of the warp threads (3) is changed by the value for the target speed (S _D ) and / or the value of the weighting function (G), in particular the value of the factor α , is changed. Method according to one of the preceding claims, characterized in that the weaving machine comprises a first and a second warp beam (2), which can be controlled separately, and that a separate, corrected desired speed (S _DK ) is determined for each warp beam (2) , and that the speed of each warp beam (2) is controlled according to the separate, corrected target speed (S _DK ). A method according to claim 5, characterized in that the separate, corrected target speed (S _DK ) of the first warp beam (2) is used as a value for the target speed (S _D ) of the second warp beam (2). Method according to one of the preceding claims, characterized in that when the warp tension (K) is exceeded or undershot from a predetermined warp tension value (K _SO , K _SU ), the corrected desired speed (S _DK ) without using a value for the desired speed (S _D ) is generated by forming a difference value between the warp tension (K) and a predetermined desired warp tension (S _K ), and the difference value weighted with the weight function (G) forms the corrected desired speed (S _DK ), with which the speed of the warp beam (2) is controlled. Method according to one of the preceding claims, characterized in that the warp thread length (L1) emitted by the warp beam (2) and the fabric length (L2) produced are measured and the actual warp incorporation (C _IST ) is determined therefrom. A method according to claim 8, characterized in that the weighting function (G), in particular the factor α, is changed depending on the actual chain incorporation (C _IST ). Device for performing the method according to one of the preceding claims, comprising a voltage sensor (5) for measuring the tension of the warp threads (3), comprising a Speed sensor (7) for measuring the speed of the warp beam (2), comprising a control device (1) which is connected to the voltage sensor (5) and the speed sensor (7) signal is conductively connected, and comprising a motor (4) driving the warp beam (2), which signal is conductively connected to the control device (1).

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