JP7181947B2 - Method, improved yarn feeding system and apparatus for optimal yarn feeding to textile machines operating in highly discontinuous or staggered motion - Google Patents

Description

The subject of the present invention is a method for feeding a yarn to a yarn processing machine according to the known requirements part of the main claim. The subject matter of the invention is also the system and the compensating device according to the known requirements part of the corresponding independent claim.

The yarn or wire is fed to a textile machine to produce a finished product (e.g. knitted goods or socks) or the yarn is optionally combined with other yarns and processed (e.g. Machines for manufacturing constant tension yarn feeders have been known for some time.

Known yarn feeders are known, in particular of the type capable of feeding yarns (including metal wires) or yarns (spinning/industrial) with constant tension. Said yarn feeder operates according to known closed loop control principles implemented in known constant tension yarn feeders. In this control method, the yarn or wire is regularly fed at a constant tension regardless of the speed at which the yarn is fed and regardless of changes in the tension of the yarn during winding on the constant tension yarn feeding device. ensure that This all depends on whether the changes in tension are due to the gradual emptying of the bobbin of yarn, or whether such changes are due to breaks or excess tension due to irregular unwinding of the yarn. whether or not

A known constant tension yarn feed of the above type is for example the subject of European Patent Publication No. 1492911 in the name of the same Applicant (published under). This prior art document describes a tension sensor, an actuator or motor acting on a feed wheel or pulley, and the thread tension measured by said tension sensor to be combined with this tension and a desired working tension (i.e. SET POINT). Discloses a yarn feeder with a control unit (or electronics) that can be evaluated by comparison with. Based on this comparison, the control unit acts on a pulley connected to the control unit by acting on the motor, inhibiting or effecting the supply of the yarn, and (in keeping with the manufacture of the product or the processing of the yarn itself) the fiber Vary or keep constant the tension of the yarn fed to the machine.

The yarn is discontinuously supplied to the textile machine, or the yarn moves according to at least one first and at least one second condition different from each other supplied to or taken up by the textile machine. Devices and systems intended to deliver (and methods of implementing them) are also known. These different supply conditions occur successively over time.

As an example, means capable of measuring the controlled tension of the yarn in real time, such as a load cell, a pulley around which one or more turns of the yarn are wound, an electric motor for rotating the pulley, and depending on the tension of the yarn to be measured , the control electronics for controlling the rotational speed of the electric motor, and thus the rotational speed of the pulleys, and keeping the measured tension consistent with a predetermined programmable value, which is preferably a function of the working phase of the textile machine. Constant tension yarn feeders are known with The rotation of the electric motor is generally controlled in two directions. One is the direction to feed the yarn to the textile machine. The other is the direction in which the yarn is withdrawn from the textile machine during the stop phase or reversed to prevent the yarn from becoming slack and to maintain the yarn at the desired tension at all times.

In this type of yarn supplying device, the yarn is unwound from the bobbin directly from the yarn supplying device and wound around the pulley. Clearly, there should be no slippage between the thread and the pulleys to ensure a constant and quality controlled tension. Only in this situation does the control electronics accurately calculate the rotational speed to which the motor actually connected to the pulley should be set to maintain the tension at the desired value.

In applications where the winding speed of the textile machine is constant or does not have large discontinuities, this type of yarn feeder can keep the measured tension constant as the feeding conditions change. Yes (variable yarn tension on loading into the yarn feeder, variation in yarn feed speed, etc.). Obviously, there is no slippage, so that under these operating conditions the yarn feeder is able to accurately measure the amount of yarn fed while maintaining the measured tension well in line with the set point. , which is another important parameter that ensures the quality of the final product.

However, known solutions of the above type have limitations in their operation when the winding speed of the textile machine changes rapidly. In applications of this kind, the speed at which the yarn is wound by the textile machine changes very quickly, for example after needle selection in a knitting machine. In this case, if the electric motor that rotates the pulley does not have the necessary power dynamic capability to handle these changes in take-up, the increased take-up will cause tension peaks in the yarn, Decreased take-up creates slack.

Both of these shortcomings in tension control (peaks and slack) can lead to quality problems in the manufactured garment (presence of stall marks due to improper tension during processing) or (due to slackness) can lead to yarn breakage and the yarn can fall out of the working means (eg needles) of the textile machine.

Clearly, the greater the problem, the less elastic the thread will help compensate for the lack of dynamic performance in the response of the electric motor.

Various solutions to this type of problem are known. For example, a yarn feeding system comprising a compensator connected upstream of a yarn feeding device (of the type described above) and acting with the yarn to help overcome the above-mentioned limitations (limitations, constraints) has been proposed by the Applicant. is known from EP-A-2262940 in the name of the same applicant (published under). After the yarn has been wound onto the pulley of the yarn feeder, the yarn feed system requires that the yarn be fed to the movable arm of the compensator and then redirected to the load cell of the yarn feeder. In this way, the compensator is in the control loop (of the tension measured with respect to the speed of the pulley of the yarn feeder) to ensure that the yarn tension remains constant as the position of the movable arm changes. is doing.

That is, according to the prior art document mentioned above, the movable arm acts as a compensating device located between the pulley (on which the yarn is accumulated) and the tension sensing means (load cell) so that the yarn is wound up by the textile machine. As it goes through each state, it is possible to compensate for changes in the state in which the yarn is fed or wound. This maintains the yarn tension at a constant predetermined value even during changes in the conditions in which the yarn is fed to the textile machine.

The movable arm of this known solution is constructed with a spring (e.g. spiral spring), the end of which is provided with an eye (e.g. made of ceramic) through which a thread is passed, and which is movable. It allows the arm to perform its compensatory action.

During use of the compensator, the operator adjusts (manually or electronically) the force of the spring so that the end of the spring through which the thread passes during the working phase is evenly centered in the angular working range. Adjust. Thus, when a change in winding by the textile machine occurs, one of the following situations can occur.

- Due to the limited dynamic performance of the pulley motor, when there is a sudden increase in take-up that the pulley motor cannot accommodate (compensate for), the time it takes for the compensating arm to descend and accelerate the pulley motor. to reduce the tension peaks in the yarn leaving the yarn feeder.

- Due to the limited dynamic performance of the pulley motor, when there is a sudden decrease in take-up that the pulley motor cannot keep up with, the compensating arm will rise to give the pulley motor time to decelerate and feed the feed. Reduce tension slack in the thread leaving the thread device.

Clearly, the ability to compensate for tension peaks and thread slack is closely related to the dynamic performance of the system (spring force) and the wide angular range over which the movable arm can move.

Said prior art document measures the position of a compensating arm used by the electronics of the yarn feeder to allow the speed of the pulley to be accelerated or decelerated, and to adjust the force of the spring by means of an electric actuator, allowing the operator to It should also be noted that allows the spring to operate automatically without manually adjusting the force of the spring.

Although this known solution works very well, it still has limitations, as will be shown below.

The compensator of this known system actually acts as a balancing mechanism, the force of the spring being manually or automatically adjusted to compensate for the tension in the thread to which it is supplied and the end of the spring. It ensures that the body can remain centered in the angular range of motion. The lighter the spring (in terms of weight), the more accurately the force of the spring will be calculated and the more reactive the spring will be in the system. However, the force of the spring is also related to the range of working tensions over which the compensator can effectively act.

For example, when calibrating a spring for medium to high tension (eg 10g) for a particular application, the force of the spring must be calculated. Conversely, if the applied tension is lower, the force selected becomes the working limit for the compensator.

Therefore, this known compensator requires the spring to be sized according to the desired working tension, rendering the system inflexible or the spring to be individually sized by the operator. or the entire compensator must be individually sized for each change in the applied tension, which is of course not always possible.

In addition, since the distal end of the compensating arm is part of the spring, it is subjected to excessive bending by the force of the thread, which makes the reading of the position of the distal end inaccurate and thus the compensator predicts This makes it difficult to use as a predictive signal for compensating actions that change the way the yarn is wound. Because the springs are flexible, they are also difficult to maintain in a particular position.

Moreover, the compensating capacity is closely related to the length of the compensating arm and the width of the angular sector, especially during the thread slack phase, and is therefore limited.

U.S. Pat. No. 4,752,044 relates to a yarn feeder with electronic tension control. This yarn feeder comprises a housing on one side of which is arranged a rotating means around which the yarn to be fed to the textile machine is wound, said yarn being engaged by braking means previously attached to this housing. At the exit from the rotating means, the yarn passes through a fixed eyelet and then through an eyelet located at the end of a movable guide arm which forms an integral part of this known yarn feeding device. At the exit from the eye of this guide arm, it engages another fixed eye before leaving the yarn feeder.

This thread guide arm is intended to create a reserve of thread F on the outlet side of the rotating means and thus downstream of the rotating means when the thread supply slows down due to changes in the winding of the thread by the textile machine. .

The yarn guide arm may be attached directly to a permanent magnet DC electric motor housed within the housing of the yarn feeding device and cooperates with a lever which is an integral part of the yarn feeding device and driven by the electric motor within said housing. You may In both embodiments, an electro-optical signal converter senses the angular position of the thread guide arm and represents the tension of the yarn to be fed, while at the same time the angular position of the thread guide arm and thus the angular position formed downstream of the rotating means. It emits a signal representing the amount of yarn stored.

The (DC) electric motor constitutes an electromagnetically controlled converter which applies a carefully predetermined and adjustable control force to the yarn guide arm. This control force is equal to the tension applied by the thread to the eye of the thread guide arm.

This control force can be adjusted by means of a potentiometer in the electrical circuit with the power supply unit that powers the DC electric motor. In this electrical circuit, a compensating signal applied to the control input to the power supply is determined, said compensating signal being set to correspond to a particular yarn tension (and thus to a constant value).

In this way, the power supply unit controls the DC electric motor to determine the equilibrium position of the yarn guide arm that it can maintain when subjected to yarn forces.

More specifically, under normal operating conditions, the thread guide arm is in a particular equilibrium angular position between two stop pins between which the thread guide arm can only move angularly. The force exerted by the thread passing through the eye attached to the thread guide arm is balanced by the force of the DC electric motor acting on the lever or the thread guide arm itself.

When the yarn feeding conditions change, for example when the yarn usage by the textile machine decreases, the yarn guide arm moves angularly with respect to the initial equilibrium position and responds to the change in position through the transducer. Generating a corresponding electrical signal. This electrical signal is sent to means for controlling the compensator. This compensator control means controls the rotation means so that the thread tension is compensated by a control force exerted by a lever acting on said thread guide arm generated by an electric motor connected to said lever or by a control force of the thread. The feed rate of the actuator acting on the yarn feed speed until the yarn guide arm returns to a predetermined equilibrium position where the tension is in equilibrium with the force generated by the electric motor cooperating with the yarn guide arm against the directly movable yarn guide arm. acts on

By means of the movement of the movable yarn guide arm, this known solution is thus able to detect changes in the yarn feeding conditions which are compensated for by corresponding actions on the rotary yarn feeder. In this solution, the thread guide arm is directly or indirectly acted upon by an electric motor whose function is only to compensate for changes in thread tension and keep the thread guide arm in a stationary position. However, the thread guide arm and the actuator cooperating directly or indirectly with the thread guide arm enable this thread guide arm to be in an equilibrium position or the thread guide arm is attached to the housing of the compensator. 2) It has a wholly passive function, since it is only the action of the rotating means on the actuator that allows it to return to its equilibrium position after moving angularly between the fixed pins. Such thread guide arms are always under a certain force and, because of the limited movement between these fixed pins, can only compensate for limited variations in thread tension.

WO 2005/111287 discloses a yarn feeder having rotary feed means controlled by an electric motor and a sensor capable of reading the tension of the yarn fed to the textile machine. Movement of the rotary feed means is controlled by a microprocessor unit which adjusts the speed of the rotary feed means in response to thread tension sensed by a tension sensor. The tension sensor consists of a rigid arm capable of moving against a resistive element as the thread tension changes at the exit from the rotary feed means and passes an idling roller or pulley mounted at the free end of the movable arm. placed at the free end. This resistance to movement of the rigid arm can be provided by a carriage that moves along rails attached to springs or yarn feeders.

The rotary feeding means and the movable rigid arm are integral parts of this known yarn feeding device.

Under operating conditions, the thread is wrapped around the rotating feed means at least once before passing the pulley at the end of the movable rigid arm. Yarn movement rotates a movable rigid arm in a direction that follows the yarn feed direction, this rotation being constrained by a resistive element (spring or carriage) and adjusted by the operator. A tension sensor senses the tension in the yarn, compares the tension in the yarn to a fixed value, and then adjusts the speed of the rotary feed means to maintain the tension in the yarn near the required value. The movement of the movable rigid arm prevents too abrupt rise in thread tension due to retraction, preventing thread breakage.

Again, the movement of the movable rigid arm is confined within a given angular sector.

In both of the known solutions of the two prior art documents mentioned above, the device described in US Pat. , which is indivisible or cannot be composed independently. The result is that these known solutions are rather complicated to implement and are rather difficult and expensive to carry out maintenance work.

International Application Publication No. WO 2013/064879, published in the name of the present applicant, discloses a method and system according to the known requirements section of the corresponding independent claims of the present application.

Said prior art document describes a metal body having a body with wire braking means, one or more pulleys controlled by respective motors on which the wire is wound, the wire passing through a compensating member and a tension sensor before reaching the working machine. A wire feeder is disclosed. Control electronics continuously measure the wire tension and apply the wire tension to a first control loop acting on the motor and a second control loop acting on the compensating member, thereby setting the wire tension to a predetermined value. can match the value of

The compensating member also has a compensating arm cooperating with the wire and having a free end which is free to rotate about a pin fixed to a bracket cooperating with the body. This compensating arm can be moved within the body of a given angular sector by moving towards or away from the tension sensor (constituted by the load cell).

The compensating arm is connected on one side to a support fixed to the body of the metal wire feeder and on the other side to a movable carriage moved by an electric stepping motor using an Archimedean or endless screw. It is

As such, the compensating arm is not directly connected to the electric motor, but the electric motor drives and moves this compensating arm through the interposition of other components each having their own inertia.

The compensating arm is coupled to a position sensor connected to the control unit so that the position sensor can measure the position of the compensating arm within a predetermined angular sector.

Thus, the compensating arm can prevent wire slippage in a dynamic rather than static manner. The control unit actually changes the position of the carriage to which the spring is mounted (acting on the electric motor), resulting in a change in the force exerted by the spring on the compensating arm, moving the compensating arm to the desired position within a given angular sector. and move. In this way, the compensating arm keeps the wire perfectly taut on the load cell or tension sensor at all times, especially during the phases in which the wire is not being fed to the textile machine.

The compensating arm also creates a reserve of metal wire from which the textile machine can retrieve metal wire in the event of an unexpected change in speed.

The prior art document on this issue furthermore discloses a feeding device comprising, as an integral component, a compensating arm which is free to move within a given angular sector.

The control system of this feeder knows the position of the compensating arm through the electric motor, and the system of springs (one or more) can determine the force to apply depending on the measured tension or read position, Thus, we have two operable closed-loop controls, a second loop related to tension (the first loop being for the electric motor coupled to the pulley) and a possible second control loop is for the position of the compensating arm.

However, the force applied to the compensating arm is manipulated through a system of springs and a movable carriage driven by an electric stepper motor which is used to vary the fulcrum of the lever and thus the force the lever exerts on the metal wire. should be noted.

In this prior art document, the problems pointed out with respect to the system disclosed in EP-A-2262940 above still apply.

Indeed, the ability of the apparatus, the subject of WO2013/064879, to compensate for wire tension peaks and slack depends on the dynamic performance of the system (spring force, moving carriage and motor) and the compensating arm's range. It is closely related to the extent of the angular sector that can be moved within.

Furthermore, also in this prior art document, the compensating arm actually acts as a balancing mechanism, the force of the spring being automatically adjusted, the force of the spring compensating for the tension in the wire being supplied, and the distal end of the compensating arm The section can be kept centered in the angular sector of motion.

Furthermore, the compensating capacity, especially in the wire loosening phase, is closely related to the length of the compensating arm and the width of the angular sector, so that this compensating capacity is limited.

In addition, this known feeding device integrally incorporates a compensating member. The result is that it is difficult to assemble with ridiculous dimensions.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved method and system for controlling the supply of discontinuously fed yarn, which system is fitted with a device for compensating for variations in yarn take-up by a textile machine. Equipped with a yarn feeder.

In particular, it is an object of the present invention to provide a system of the above type with a compensator inserted into the control loop (tension measured with respect to the speed of the yarn feed pulley) when the yarn is fed to the textile machine. This system overcomes the limitations of existing solutions.

Another object of the present invention is the step of removing yarn from the textile machine during said discontinuous supply to the textile machine and between the steps of supplying yarn to the textile machine and the step of interrupting the supply of such yarn. To provide a method of the above type that can actively or dynamically compensate for changes in tension experienced by the yarn during both

Yet another object of the present invention is to provide an independent compensator suitable for use in systems of the type described above that does not change its dynamic characteristics with respect to a set applied tension, and is therefore flexible and easy to use. It is to be.

Another object of the present invention is to allow accurate measurement of the position of the compensating means and to act predictively when the yarn begins to undergo tension changes at the start of different stages in the discontinuous feeding to the textile machine. The object is to provide a compensator of the above type which can also

Yet another object of the invention is to enable the system to which it belongs to be able to recover more yarn during the yarn slackening or reversing phases of the textile machine compared to the amount of yarn that can be recovered by known systems. The object is to provide a compact compensator which can also be applied as an additional element of a feeding device for sizing.

These objects, and others which will be apparent to those skilled in the art, are achieved by methods, supply systems and compensating devices as set forth in the appended claims.

To enable a better understanding of the invention, the following drawings are attached purely as non-limiting examples.

1 shows a front view of an example of a compensating device according to the present invention mounted on a known yarn feeding device to control the tension of yarn fed to a textile machine; FIG. Figure 2 shows a side view of the yarn feeder and compensator shown in Figure 1; 2 shows a perspective view of the compensating device and the yarn feeding device according to the invention of FIG. 1; FIG. 1 shows a front perspective view of a compensating device according to the invention; FIG. 1 shows a side view of a compensator according to the invention; FIG. 1 shows an example of use of a compensating device according to the invention from above; 4 shows another example of the use of the compensating device according to the invention from above; 5 shows from above a further example of the use of the compensating device according to the invention; 1 shows a view from below of a compensating device according to the invention; FIG. 1 shows a block diagram of an example of how a system according to the invention may be used; FIG. Fig. 3 shows a block diagram for another example of the use of the system according to the invention; Fig. 3 shows a block diagram for yet another example of how the system according to the invention may be used; Fig. 3 shows a graph of the tension of the thread fed to the textile machine in the situation where the compensating device object of the invention is not in operation; 1 shows a graph of the tension of a yarn fed to a textile machine in the situation where the compensator object of the invention is operating in passive dynamic mode; Fig. 3 shows a graph of the tension of the yarn sent to the textile machine in the situation where the compensator object of the invention is working in active prediction mode;

With reference to the aforementioned drawings (corresponding parts are provided with the same reference numerals in these drawings), and in particular to FIG. A yarn F (indicated by a dotted line in FIG. 1) is attached to one end 2A of a yarn feeding device or simply a feeding device 2 that supplies the textile machine T with a constant tension (in other words, on one side placed). The thread F may be a metal wire and may be fed to a working machine such as a winder. The compensating device 1 is a distinctly independent element relative to the yarn feeding device 2 in terms of construction and use.

The yarn feeder 2 preferably comprises a tension sensor 3, a pulley (or equivalent yarn storage means) 4 driven by its own electric motor (not shown) and a microprocessor known per se. It has a control unit or electronics 60 (see FIGS. 10A-10C). This control unit or electronic device evaluates the yarn tension sensed by the tension sensor 3 as the yarn is fed to the textile machine and sets the sensed tension to a predetermined value (i.e. SET POINT). and (if the sensed tension differs from the desired value) acting on said electric motor and thus on the pulley 4, the thread tension can be adjusted. This yarn feeder 2 and its tension sensor 3 and pulley 4 are of a known type and perform a known operation and will not be further described.

The yarn feeding device, as mentioned, enables the yarn to be fed with constant tension to the textile machine, which is the manufacturing unit of the product or the machine for processing the yarn.

The compensating device 1 and the yarn feeding device 2 constitute a yarn F feeding system according to the present invention.

The compensating device 1 according to the invention can cooperate with the thread after it has passed the pulley 4 . This compensator is therefore in the thread tension control loop, as can be seen from FIG. 1 and as will become clear from the description of the method according to the invention. With the present invention, it is possible to improve the dynamic performance of the yarn feeding system, allowing it to immediately compensate for sudden changes in yarn winding (positive or negative), resulting in To enable a pulley motor to change to a new yarn supply speed required by a new winding state without causing plus or minus peaks in yarn tension.

By virtue of the compensator 1 being in the control loop, it always ensures that the tension of the yarn leaving the yarn feeder 2 is always the same in the set.

The compensating device 1 is an independent device with respect to the yarn feeding device 2 and comprises an electric motor 8, for example a DC governorless motor, preferably with very low inertia and enhanced dynamic performance. In the exemplary embodiment of the invention, the electric motor 8 directly drives a drive shaft which has two portions projecting from opposite sides of the electric motor itself. In the drawings, the first part of the drive shaft is indicated by reference number 7 (see FIGS . 6-8 ) and the second part is indicated by reference number 10 as shown in FIG. The electric motor is also inserted into the body 11 of the compensator. A rigid arm 13 (eg attached to the drive shaft itself) is mechanically attached to the first portion of the drive shaft. At the end 14 of the rigid arm 13 there is also a ring 16 (or other shape) of ceramic (or other material) through which the thread passes.

The electric motor 8, as mentioned above, preferably has a very low inertia so that the force of the yarn causes the rigid arm 13 to move rapidly, thus causing the rigid arm to exert tension peaks on the yarn itself. Quickly compensate for this motion without causing it.

However, the rigid arm 13, when pulled by the thread F, both when the electric motor has (preferably) very low inertia and when the electric motor has limited inertia, It may rotate freely (rotate the electric motor) about the axis M (or the axis of the drive shaft). In any case, this rigid arm has a zero or initial rest position which is adopted when the yarn F is wound by the textile machine without tension change and without interruption (e.g. See Figure 6).

The rigid arm 13 and electric motor 8 assembly (ie substantially compensator 1) can operate in two different modes: passive dynamic mode or active predictive mode.

In the passive dynamic mode, the electric motor rotates itself while allowing the rigid arm 13 (attached to the drive shaft) to be pulled by the thread from its rest position. However, this electric motor acts to return the rigid arm 13 to its rest position after said movement. In this or working mode, the electric motor operates essentially as a "dynamic" spring, the force of which the electric motor acts on the rigid arm 13 to program the torque of the electric motor and/or Or it can be programmed by controlling.

However, this force is not pre-determined and fixed (as in the solution of US Pat. No. 4,752,044), but automatically adapts to thread tension settings at various stages of the manufacturing process, Whatever the set working tension of the thread for each particular stage in the manufacture of the product can be varied to keep the rigid arm in place at all times. This causes the electric motor 8 to move the rigid arm 13 (to which it is always directly connected) to its equilibrium position ( For example, the position of "3 o'clock" in FIG. 6) can be maintained.

The variability of this drag or action on the rigid arm 13 of the electric motor is explained below.

In the active predictive mode, the electric motor 8 anticipates (in the "predictive" mode) as soon as the electric motor senses a change in yarn tension (sensed by the tension sensor 3) due to a change in the working phase of the textile machine. can be active. In this case, the electric motor 8 moves the rigid arm 13 carried on the drive shaft into a compensating position where the change in tension can be compensated. If this change in tension tends to rise, the electric motor 8 will move the rigid arm to the "6 o'clock" compensation position in FIG. ) If the thread tension tends to fall, the electric motor moves the rigid arm 13 to the "12 o'clock" compensation position in FIG. This allows the thread tension to remain constant independently of the operation and production stage of the textile machine T.

Figures 11A-11C show the tension curves for situations in which the electric motor and rigid arm assembly or compensator 1 is in a non-active state (Figure 11A), in passive dynamic mode (Figure 11B) or active FIG. 11C shows the tension curve (FIG. 11C) for the situation in predictive mode.

In these figures (FIGS. 11A-11C), the curves or lines F, K, W and Y are respectively the set yarn tension (curve F) (in the manufacturing run), the measured yarn tension ( curve K), the setpoint position of the rigid arm 13 (curve W) and the actual position of the rigid arm 13 (curve Y). In these figures, time is the abscissa and the ordinates are the measured tension values for F and K, and the position values for W and Y.

As can be seen by comparing these figures, when the compensator 1 is not in operation, the measured yarn tension has more peaks and fluctuations compared to the other situations shown in FIGS. 11B and 11C. It can also be seen from a comparison of Figures 11B and 11C that the yarn tension is less variable in the situation where the compensator 1 is operating in the active prediction mode. Finally, in FIG. 11C the rest position of the rigid arm 13 (curve W) is not predetermined and follows the change in tension of the thread, this rest position also follows the compensation effected by the compensator 1. It can be seen that it is followed by the "current" position of the medium and rigid arms.

The second portion 10 of the drive shaft supports a magnet 18 which, together with a rigid arm 13 attached to the electric motor 8, is free to move about its axis M within a particular circular sector. Rotate (rotate the drive shaft). Alternatively, the assembly with rigid arm 13 and magnet 18 may be free to rotate through a complete revolution about the axis of rotation M (drive shaft axis). In other words, the rigid arm 13 and the magnet 18 are both splined to the drive shaft so that they both rotate about the axis M freely or in angular sectors as well. In this way, by detecting the position of the magnet, the position of the hard arm 13 can be grasped immediately.

For this purpose, a position detector 19 is arranged around the magnet. For example, one or more linear Hall sensors 20 are arranged around the magnet, which are able to generate a position signal which is sent, for example, to the control unit 70 of the compensating device 1 . Data from the linear Hall sensors allows this control unit 70 to convert the rotation of the electric motor into two sinusoids (sine and cosine) offset by 90 degrees, from which the drive shaft's The absolute position, and therefore of the rigid arm 13 fixed to the drive shaft and magnet 18 and cooperating with the thread, can be obtained in real time.

In one example of embodiment, the control unit preferably also comprises a system (known per se) for driving the electric motor and controlling the speed of rotation of the electric motor and the applied torque.

There is also a real-time data exchange between the control electronics 60 of the yarn feeder 2 and the control unit 70 of the compensator 1 to set the desired torque of the electric motor of this compensator 1 and then to rotate the electric motor. It is preferable to be able to control and read the position of the electric motor (and thus the position of the rigid arm 13 in a direct and immediate manner). The setting of the torque is dynamic and not fixed as it depends on the set thread tension or the thread tension sensed by the tension sensor 3 .

Information exchange may be done one of over a serial bus, using digital or pulse width modulated (PWM) signals, or using analog signals.

Thus, the yarn feeding device 2 (via its control electronics 60) cooperates with the compensating device 1 to know in real time, in a reliable and immediate manner, the position of the rigid arm 13 and the electric motor of the compensating device 1. It is clear that the torque/shift/speed applied to the can be adjusted. This is because the drive shaft and the rigid arm are directly connected or because the electric motor acts directly on the rigid arm.

By appropriate handling of the position signals received with respect to the rigid arm 13 and appropriate control of the electric motor acting on this rigid arm, the yarn F feeding system according to the invention can therefore be applied to the rigid arm 13 in an almost instantaneous manner. A second control loop for the position of the arm 13 can be closed to keep the rigid arm in a desired position, for example the middle position of the rigid arm ("3 o'clock"), when the set tension changes. . This compensates for variations in yarn movement and yarn tension associated with the various working stages of the textile machine.

10A and 10B, the system according to the invention can be implemented in different forms.

1. The compensator 1 has its own control unit 70 intended to receive the stationary position reference (indicated by block 80 in FIGS. 10A and 10B) from the control electronics 60 of the yarn feeder 2. and the rest position reference is that which the rigid arm must maintain when the set or sensed tension in the thread F changes. The control unit 70 cooperates with means (magnets 18) for measuring the positions of the rigid arm 13 and the drive motor 8 (blocks 81 and 82). The control unit thus closes the control loop for the position of the rigid arm 13 .

2. Instead of doing this, data about the position of the rigid arm 13 is received from the magnet, which in turn sets the torque value for the electric motor 8 (based on the set or sensed thread tension) and the position of the rigid arm. It is preferably the control electronics 60 of the yarn feeder 2 that provides the closed loop control over the position. In this case, the drive means of the electric motor 8 are either in the control unit 70 of the compensator 1 (to which the reference is sent by the yarn feeder) or (as explained below) in the yarn feeder 2 . may be located in the control electronics 60 of the This solution is preferred because the control electronics 60 of the yarn feeder 2 not only know the position of the rigid arm, but also directly (because it is connected to the tension sensor 3) the measured tension of the yarn. Knowing this, the two pieces of information can then be used to optimize the performance of the system according to the invention. For example, when such control electronics detect that the yarn tension is rising due to a sudden demand for yarn from the textile machine T, the control electronics will move the rigid arm, for example, from "3 o'clock" to " By moving to "6 o'clock", it can be decided to automatically change the position set point of the rigid arm 13 . This follows the active anticipatory working mode of the electric motor 8 and rigid arm 13 assembly previously shown.

This feature also uses not only the low inertia electric motor 8, but also its dynamic performance to compensate for the situation, so peak tension can be further reduced. Obviously, the same applies to the phase when the winding suddenly slows down. All this can indeed be seen from a comparison with FIG. 11C and the previously mentioned FIG. 11B.

The electronics of the yarn feeding system according to the invention (i.e. the control unit 70 of the compensating device 1 or the control electronics 60 of the yarn feeding device 2, as previously described), (depending on the tension sensed in the yarn F ) By continuing to read the position of the rigid arm 13 and appropriately controlling the torque of the electric motor associated with the rigid arm 13, the position of the compensating arm 13 can be maintained at the desired value. Therefore, this torque value is such that the rigid arm 13 is brought into equilibrium in its rest position, e.g. allow it to be maintained. This does not have any delay in action on the rigid arm 13 as occurred with the solution in WO2013/064879.

Thus, an increase or decrease in thread tension causes the rigid arm 13 to move from its equilibrium position to always maintain the thread at a set working tension, for example as shown below.

a) During processing, if the set thread tension needs to be increased, the rigid arm 13 will obviously be lowered (moved towards the "6 o'clock" position in FIG. 7). , the electronics of the yarn feeding system according to the invention (i.e. the control unit 70 of the compensation device 1 or the control electronics 60 of the yarn feeding device 2) reading this change in position calculates the new torque to be applied to the electric motor 8 and , returning the rigid arm 13 to the rest position;
b) During processing, if the set thread tension needs to be reduced, the rigid arm 13 will obviously rise (moving towards the "12 o'clock" position in FIG. 8). , the control unit of the compensator reading this change in position or the control electronics of the yarn feeder calculates a new torque to apply to the electric motor 8 to return the rigid arm 13 to the rest position.

In this way, the control electronics of the yarn feeder can automatically, quickly and accurately control the position of the compensating arm 13, as it is mounted on the drive shaft, so that the operator can It is possible to change the working tension at will during the production cycle, for example to make a gradual change in tension during the manufacturing cycle of the product (eg the gradual compression force of medical socks). Each change in tension always adopts the rest position (e.g. "3 o'clock") or the rigid arm is returned to the rest position to adjust the "current" tension of the yarn or the specific feed required for a particular manufacturing step. Accompanied by a change in the torque of the electric motor applied to the compensating arm 13 which keeps the tension exhibited by the yarn constant during the yarn phase.

In other words, the yarn feeding system according to the invention comprises a control unit (compensator 1 or yarn feeder 2), for example incorporating a microprocessor, which controls the actuation of the electric motor which directly moves the compensating arm 13. Control. However, this compensating arm, together with the drive shaft to which it is connected, is used when the tension of the yarn passing through the loop 16 supported by the compensating arm 13 changes as a result of changes in the winding or feeding conditions of the textile machine. , initially free to move about axis M (thus rotating the electric motor).

Changes in the position of the compensating arm 13 (relative to a predetermined reference or rest position, e.g. "3 o'clock") are sensed by the control unit of the yarn feeding system according to the invention through signals coming from the position sensing means 19 . These data are sent to said electronic control unit (60, 70) of the yarn feeding system according to the invention for closed loop control.

The control unit 70 of the compensating device 1 is in particular able to detect how far (angularly) the compensating arm 13 has moved from its reference position, and based on this value the control electronics 60 of the yarn feeding device 2 However, the power supply to the pulley 4 motor can be monitored, varied and controlled so that the pulley motor changes its rotational speed to compensate for the angular movement of the compensating arm 13 relative to the reference position. In this way, the yarn feeder 2 uses information about the position of the compensation arm 13 to anticipate changes (acceleration/deceleration of the pulley 4) and further improve the payout tension. This follows the "active prediction" mode of operation previously described.

Thus, also in this case (as in EP-A-2262940) the compensating device 1 acts as a "balancing mechanism" and the control electronics of the yarn feeding system according to the invention cooperate with the compensating arm 13. The torque applied to the working electric motor 8 is calculated in real time to keep the compensating arm in balance at all times in a fully automatic manner. This is done depending on the "current" tension of the thread F (obviously maintaining a given tension).

Controlling the position of the compensating arm 13 in this manner will also have a compensating effect on payout tension, which leads to total elimination or a dramatic reduction in tension peaks and slack in the thread itself. . In fact, when the textile machine T suddenly increases the demand on its yarn F and the dynamic performance of the electric motor driving the pulley 4 is insufficient to compensate for these changes, the compensating arm 13 is lowered. (moving towards the "6 o'clock" position), increasing the amount of yarn F fed to the textile machine T. This is done until the electric motor of pulley 4 reaches the rotational speed required to eliminate or reduce tension peaks. Once the required rotational speed has been reached, the compensating arm automatically returns to its initial or rest position.

Conversely, if the textile machine T abruptly reduces its demand on its yarn F and the dynamic performance of the electric motor driving the pulley 4 is insufficient to compensate for such changes, the compensating arm 13 is raised. (moves toward the "12 o'clock" position in FIG. 8), reducing the amount of yarn F sent to the textile machine T. This is done until the electric motor of the pulley 4 reaches the rotational speed required to eliminate or reduce thread slack. Once the required rotational speed has been reached, the compensating arm automatically returns to its initial or rest position (Fig. 6).

In the first embodiment of the invention, the rest position of the compensating arm 13 is within the range of motion of the compensating means or compensating arm 13 having two limit points (ie 6 o'clock and 12 o'clock).

In addition, since the position of the compensating arm 13 is accurately grasped in real time, the control electronic device of the yarn feeding device 2 uses this information to accelerate or decelerate the rotation of the pulley 4, thereby achieving a new target speed. It is possible to minimize the time to obtain and maintain a constant preset value of tension in the yarn F, and to limit the magnitude of tension peaks or slack in the yarn F.

Also, since the position of the compensating arm 13 and the value of the tension measured by the tension sensor 3 are known accurately in real time during transitions (changes in winding), the yarn feeding system according to the present invention By varying the driving force of the electric motor 8 cooperating with the yarn feeder 2, variations in the payout tension of the yarn feeder 2 can be even less. for example:
i) During the rapid acceleration phase, the compensation arm 13 will be lowered (moved towards the "6 o'clock" compensation position in FIG. 7) and the measured thread tension will increase. In this case, the control electronics of the yarn feeding system according to the invention can make the following determinations.

1) By discontinuing or lessening the closed-loop control of the position of the compensating arm 13, the yarn can lower the compensating arm 13 until the yarn tension is within predetermined limits, so , from "3 o'clock" to "6 o'clock" is used as a stock of yarn F to be supplied;
2) Automatically set the working setting of the compensating arm 13 to a lower position and feed more yarn F to the textile machine until the critical condition is overcome.
ii) During the rapid acceleration phase, the compensating arm 13 will rise (moving towards the "12 o'clock" compensating position in FIG. 8) and the measured thread tension will drop. In this case, the yarn feeding system according to the invention can make the following decisions.

1) By discontinuing the closed-loop control of the position or reducing the influence of the position control loop, the compensating arm 13 can retrieve the yarn F until the yarn tension is within predetermined limits, so that Use the interval moving from "3 o'clock" to "12 o'clock" to act to collect the excessively supplied yarn;
2) Automatically set the working setpoint or rest position of the compensating arm 13 to a higher position and feed less yarn F to the textile machine until the critical condition is overcome.

The setpoint or reference value for the position control loop of the compensating arm 13, hitherto thought to be, for example, the "3 o'clock" value (Fig. 6), is instead variable and controlled by the control electronics of the yarn feeder. Appropriately dynamically handled and prepared for the next feeding stage that may occur (for example). For example, during the phase in which the yarn is slowed down by the textile machine and then stopped, the set point can automatically change to the 12 o'clock position, so that more stock of yarn F is available on restart. is ready for acceleration and the next tension peak is further reduced.

Another embodiment of the invention (already included in the drawing) comprises a drum or cylinder 26, also attached to the compensating arm 13, on which the thread is wound during the recovery phase, so that it is stored The amount of thread F increases. This is because the size of the angular sector of rotation has increased, in which case the angular sector of rotation is no longer confined between 6 o'clock and 12 o'clock, and the compensating arm is free to rotate about the axis of rotation M. can.

The drum on which the yarn is wound may be mounted on a compensating arm 13 and may rotate freely on bearings that make the rotation of the drum independent. The diameter of the drum determines the maximum amount of yarn F that can be recovered from the compensator 1/yarn feeder 2 system. This drum may therefore have different dimensions depending on the amount of yarn F desired to be collected and wound onto the drum. The drum may be cylindrical, semi-cylindrical, or have a shape with varying cross-sections.

The compensator operates without mechanical stops that prevent the compensator from rotating beyond the 6 o'clock to 12 o'clock arc, allowing unrestricted rotation of the compensating arm 13 about its axis during the recovery phase. You may make it possible. In this case, the compensating arm 13 is free to wind onto the drum 26 more yarn which it stores during the recovery phase, which is then fed back to the textile machine on the next restart. .

This provides a "reservoir" for two threads, the drum 26 in addition to the pulley 4 .

The present invention allows a single "system" to operate at very different yarn feed tensions without requiring any action by the operator. Not only is this system able to compensate for abrupt changes in the yarn feed without causing tension peaks or slack in the yarn, it is also slightly less than in the solutions previously described in the prior art. A larger amount of yarn F can be collected.

While various embodiments of the invention have been described, of course still other embodiments are possible. For example, the ceramic annulus attached to the compensating arm 13 may be replaced by a hose made of some other material having sliding properties suitable for the application. Additionally, although the specification describes the use of DC motors with brushes, it is clear that any type of electric motor or actuator (brushless, stepper, etc.) or pneumatic motor or actuator can be used. is.

Although the use of an encoder with a Hall sensor to detect rotation of the drive shaft has been described, any commercially available encoder can be used and the Hall sensor can be incorporated into the motor. In this case, it is not necessary to have drive shafts protruding on both sides.

In addition, although the compensating arm 13 is rigid, it may also absorb compensating effects by having its own minimal flexibility, such flexibility depending on the material or cross-section from which the compensating arm is made. It is derived from Further, although the compensating arm is described as rotating, the rotating compensating arm may be linear using a linear actuator or linear motor that moves longitudinally through positions corresponding to 6 o'clock, 3 o'clock and 12 o'clock. You can replace it with an exercise arm.

So far, the existence of a control unit of the compensating device 1 cooperating with the control electronics of the yarn feeding device 2 has been described. However, it is clear that this control unit may also be the control unit of the yarn feeding device 2 (i.e. the control unit may be part of the control electronics of the yarn feeding device) and the compensation When the body 11 of the device 1 is attached to the yarn feeding device 2, it can run automatically and the presence of the compensating device 1 (a suitable connector not shown (through this connector the control unit can control the compensating device 1 The presence of the body 11 (detected by encoders or position sensor means for the drive shaft attached to the motor and compensating arm 13) of the body 1) can be automatically recognized. This solution is shown in FIG. 10C.

The invention is used for supplying spun yarn, but also for supplying metal wire.

These implementation variations are also to be considered within the scope of the invention as defined in the following claims.

Claims (15)

A method of feeding a thread comprising a metal wire or a sewing thread to a textile machine (T) at constant tension or to a machine for processing metal wire, said feeding wherein the thread (F) is different from each other in the feeding or fiber a series of stages moving in at least a first state and at least a second state of winding by the machine, performed discontinuously, said first state and said second state occurring one after the other, said feeding being , a tension sensing means (3), a yarn accumulating means (4) driven by its own electric motor and connected to said tension sensing means (3) and yarn accumulating means (4), said tension sensing means (3) by a yarn feeding device (2) having control means (60) operable to act on said yarn accumulation means (4) on the basis of the tension value obtained, before cooperating with said tension sensing means (3). There is a compensating device (1) attached to the yarn feeding device (2) cooperating with the yarn (F) coming from the yarn accumulating means (4), said compensating device (1) for each first Changes in the supply or winding state of the yarn (F) during the transition between the supply or winding state and each second supply or winding state following each first can be compensated for, which is the Control means (60) for the device act on the yarn accumulation means (4) to vary the action of the yarn accumulation means on the yarn to keep the tension value sensed by the tension sensing means (3) constant over time. so that it can be maintained equal to a set value, said constant tension being maintained even during the phases of changing feed conditions, due to the interaction between said yarn and said compensator (1), said compensator ( 1) comprises, at one free end, a movable compensating means (13) supporting a harness (16) capable of cooperating with the thread (F), said movable compensating means being a winding of the thread. When transitioning from a state of less take up to a state of more take up, it is possible to move from a predetermined rest position in the feeding direction of the yarn (F), but the yarn (F) moves from a state of more take up to less. When transitioning to a state, it moves in the opposite direction and said compensating means (13) is directly and rigidly attached to it in such a way that it returns to its rest position after such a change in winding. , the control of the movement of said compensating means (13) is carried out by means of a corresponding electric motor (8) of the compensating means itself, which can directly control the movement of said compensating means, the compensating arm (13) being adapted to control the movement of the thread (F). controlled according to the set or sensed tension and the position measured during each stage in which the yarn is fed to the textile machine, The compensating means ( 13 ) is rigid,
The compensating means (13) and the electric motor (8) controlling the compensating means in motion operate in active anticipation mode, said electric motor (8) moving the compensating means (13) from the rest position to the thread (F). moving to a compensating position corresponding to changes in the tension of the tension upon detection of such changes. The compensating means (13) and the electric motor (8) of the compensating means, which directly and precisely controls the compensating means in motion, operate in a passive dynamic mode, said compensating means (13) controlling the force of the thread (F). Underneath, together with the electric motor, it is free to move, but after such movement it is returned to a rest position by the electric motor (8), said electric motor (8) being activated when the yarn is fed to the textile machine. 2. A method according to claim 1, characterized in that it generates a torque capable of maintaining said compensating means in a rest position with respect to the thread (F). 2. A method according to claim 1, characterized in that a control unit (60, 70) directly or indirectly connected to the tension sensing means (3) provides continuous control of the electric motor (8) of the compensator. law. rotating said compensating means (13) out of control by an electric motor about a fixed axis (M) of the drive shaft to which said compensating means (13) is fixed or along the compensating device (1); 2. The method of claim 1, comprising moving. 2. The method according to claim 1, characterized in that, in addition to the yarn accumulation in the yarn accumulation device (4) of the yarn feeding device (2), an accumulation of the yarn (F) in the compensation device (1) also takes place. Method. 5. Method according to claim 1 or 4 , characterized in that the movement of the compensating means (13) is angularly limited or not. A system for supplying metal wires or threads, including sewing threads, with constant tension to a textile machine (T) or a metal wire processing machine, said feeding being discontinuous or by textile machines in which the threads (F) are different from each other In a series of steps moving in at least a first and at least a second state of feeding or winding, said states occurring one after the other, said system operating according to the method of claim 1, said tension sensing means ( 3) and a yarn accumulating means (4) driven by its own electric motor and said tension detecting means (3) connected to said yarn accumulating means (4) and adapted to the tension obtained from said tension detecting means (3). a yarn feeding device (2) having control means (60) operable to act on said yarn accumulation means (4) based on said yarn accumulation means (4); 4) with a compensating device (1) attached to said yarn feeding device (2) cooperating with the yarn (F) leaving said compensating device for each first and each second feeding following each first; Changes in yarn (F) feeding or winding during transitions between yarn or winding conditions can be compensated for by the control means (60) of the yarn feeding device acting on the yarn accumulation means (4). to change the action of the yarn accumulating means on the yarn so that the value of the tension detected by the tension detecting means (3) can be maintained constant over time equal to the set value, and the constant tension is applied to the yarn and the Due to the interaction with the compensator (1), which is maintained even during the phase of change in yarn feeding conditions, the compensator (1) allows the yarn to change from being less wound by the textile machine to being more wound. When transitioning to the heavy state, it can be moved from a predetermined rest position in the feeding direction of the yarn (F), but in the reverse direction when transitioning from the state of more winding to the state of less winding. In a system comprising a movable compensating means (13) which can be moved, said compensating means (13) returning to a rest position after this change in winding, said compensating means (13) is adapted to the yarn (F ), said rigid arm (13) being rigid arm (13) depending on the set or sensed tension of the thread (F). directly fixed to an electric motor (8) on its own rigid arm which directly controls the movement of the rigid arm, said rigid arm being located between said yarn accumulating means (4) and said tension sensing means (3) is not connected to the tension detection means,
Position sensing means (19) are provided for measuring the spatial position of the rigid arm (13), said position sensing means (19) being attached to the drive shaft of said electric motor and carrying said rigid arm. A system characterized by The rest position of the compensating means (13) is within the range of motion of such compensating means with two limit positions or within a circular path of the compensating means about an axis, said circular path being angularly 8. The system of claim 7 , wherein the system is not limited to A control unit (60, 70) for the electric motor (8) of the compensator (1) is provided, said control unit being connected to the position sensing means (19) and through said position sensing means (19). The movement of (13) from the predetermined rest position can be detected, and the compensation means (13) can be returned to the predetermined rest position by the control of the electric motor to which the compensation means (13) is directly fixed. , said control unit (60, 70) is directly or indirectly connected to the yarn tension sensing means (3), said control unit controlling said yarn (F) while it is fed to the textile machine. 9. A system according to claim 8 , characterized in that it controls the electric motor on the basis of the thread (F) tension sensed at . Said control unit (60, 70) is attached to the compensation device (1) and connected to the control means of the yarn feeding device (2), or said control unit is connected to the control means of the yarn feeding device (2). 10. The system of claim 9 , wherein the system is a part. The compensating device (1) is a component independent of the yarn feeding device (2), the compensating device (1) is detachably attached to the yarn feeding device (2), and is attached to one end of the yarn feeding device. (2A) or placed on one side, said compensating device (1) is fully automatic with respect to said yarn feeding device (2), but when said compensating device is connected to said yarn feeding device, 8. System according to claim 7 , characterized in that the compensating device (1) is closely connected to the yarn feeding device (2). Means ( 26 ). Compensating device suitable for use with a thread feeding device (2) for feeding a thread (F) comprising a metal wire or sewing thread to a textile machine (T) or a metal wire processing machine with constant tension, said textile machine or the metal wire processing machine is part of a system according to claim 7 , wherein said compensating device (1) operates discontinuously and said compensating device (1) operates according to the method of claim 1; has movable compensating means (13) capable of cooperating with said yarn (F) before it leaves said yarn feeding device (2), said compensating means (13) moving it It is constituted by a rigid arm fixed to the means, said rigid arm movably cooperating with the thread (F), the rigid arm allowing the thread to be less wound by the textile machine or the metal wire processing machine. When transitioning from a state with more windings to a state with more windings, it is possible to move from a predetermined rest position in the feeding direction of the yarn (F), but from a state with more windings of yarn (F) A position sensing means (19) capable of moving in the opposite direction when transitioning to the lesser state and capable of sensing movement from said rest position is provided, said position sensing means (19) , the tension of the thread (F) can be sensed directly or indirectly, and after moving said rigid arm from its rest position by controlling the actuator means on the basis of the set or sensed tension, A compensating device for returning to a rest position, characterized in that the compensating device is an independent device compared to the yarn feeding device (2) and is arranged to the side of said yarn feeding device (2). The means for moving the rigid arm is preferably a very low inertia electric motor (8) which is directly connected to said rigid arm (13) through its drive shaft to move the rigid arm ( 13), the rigid arm, when pulled by the thread (F), is free to rotate about the axis (M) of the drive shaft and, under the action of the electric motor, remains stationary. 14. A compensating device according to claim 13 , which is returned to a position. 14. Compensating device according to claim 13 , characterized in that it comprises rotating means (26) capable of receiving the yarn on its circumference when the textile machine is at rest or in the stage of returning the yarn to the feeding process.

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