IT201800002452A1 - METHOD, IMPROVED YARN FEEDING SYSTEM AND DEVICE TO OPTIMIZE YARN FEEDING TO A TEXTILE MACHINE OPERATING WITH HIGH DISCONTINUITY OR WITH AN ALTERNATING MOTION - Google Patents

Description

Description of an invention patent

DESCRIPTION

The present invention relates to a method for feeding a thread to a machine which processes it according to the preamble of the main claim. The invention also relates to a system and a compensating device according to the preamble of the corresponding independent claims.

Constant tension thread feeders have been known for some time, suitable for feeding a thread or yarn to a textile machine, both suitable for producing a finished product (for example a knit or a sock) and for processing such thread, possibly in combination with others. threads (for example machines for preparing the yarn for subsequent uses).

In particular, yarn feeding devices of the type capable of feeding constant tension threads (including metallic ones) or yarns (textile / technical) are known. Said devices operate according to a known closed-loop control methodology obtained with a known constant voltage wire feeder. The control method ensures the regular feeding of a thread or yarn at constant tension independently of the feeding speed of said yarn and also independently of the variation in tension of the yarn at the input of said constant tension yarn feeder; all of this whether the tension variation is due to the gradual emptying of the yarn bobbins, or whether these variations are due to tears or extra tensions deriving from the irregular unwinding of said yarns.

A known constant voltage wire feeder of the aforementioned type is, for example, the subject of EP1492911 in the name of the same Applicant: this prior text describes a feeder comprising a tension sensor, an actuator or motor acting on a wheel or pulley power supply and an (electronic) control unit capable of analyzing the thread tension value measured by the aforementioned sensor comparing it with a desired working voltage value (or SET POINT). On the basis of this comparison, the control unit intervenes on the motor so as to operate on the pulley connected to it by braking or feeding the thread in order to modify or maintain constant the tension of the thread itself fed to a textile machine (for the production of an article or processing the wire itself).

Also known are devices and systems (and the methods implemented by them) suitable for feeding a yarn with discontinuity to a textile machine or with a method according to which the movement of the yarn occurs with at least a first and at least a second state of feeding or absorption. by the different weaving machine. These different states of power follow each other over time.

By way of example, a constant voltage wire feeder is known comprising a member, for example a load cell, suitable for measuring in real time the tension of the controlled wire, a pulley on which the wire is wound with one or more turns , an electric motor that rotates the pulley, and a control electronics that, according to the measured wire tension, adjusts the rotation speed of the motor and consequently of the pulley to keep the measured voltage value aligned to a predefined value and programmable, possibly depending on the operating phase of the textile machine. The rotation of the motor is generally controlled in both directions, the first to help the yarn to the machine, the second to recover it from the machine during the stop or inversion phases to prevent the yarn from loosening and always maintaining the desired tension.

With this type of feeder, the yarn is picked up from a cone directly from the device and is wound on the pulley. Obviously, to ensure consistency and good quality of the controlled voltage, there must be no slipping between wire and pulley: only and only in this case, in fact, the control electronics are able to calculate precisely the speed to be set on the motor associated with the pulley to maintain the tension equal to the desired value.

In applications where the absorption speed of the machine is constant or does not have strong discontinuities, this type of power supply is able to keep the measured voltage constant, as the power supply conditions vary (variable wire voltage at the power supply input, variations in feed rate, etc.). Obviously, since there is no slipping, in these working conditions the power supply is able to keep the measured voltage perfectly aligned with the set value and at the same time accurately measure the quantity of wire fed, another fundamental parameter to guarantee the quality of the finished product.

The known solutions of the aforementioned type, on the other hand, have operating limits when the variations in the speed of absorption by the textile machine change abruptly. In this type of application, the speed at which the yarn is picked up by the textile machine varies very quickly, for example to follow the selection of the needles of a knitting machine; in this case, if the motor that rotates the pulley does not have the necessary dynamics to follow these variations in output absorption, there are voltage peaks in the wire, when the absorption increases and voltage slackening when the absorption decreases.

Both of these defects in the tension control (peaks and loosening) can cause quality problems in the garment (presence of shadows due to an incorrect tension during the row being processed) or lead to the breakage of the yarn itself (due to a voltage peak). or at the exit of the thread from the operating member (for example the needle) of the weaving machine (due to a loosening).

Obviously the problem is greater the less is the elasticity of the wire which helps to compensate for the lack of dynamics in the response of the engine.

Various solutions to this type of problem are known: for example, from EP2262940, in the name of the same Applicant, a feeder system comprising a compensating device to be connected upstream of the feeder (of the type described above) and which cooperates with the wire , it helps to overcome the limitations previously described. This system provides that the wire, after being wound on the feeder pulley, is directed to a movable arm of the compensating device and subsequently redirected to the load cell of the feeder. In this way, the compensator device is located inside an adjustment ring (voltage measured with respect to the speed of the power supply pulley) to ensure that the wire tension always remains constant as the position of the mobile arm varies.

In other words, according to the aforementioned prior art, the movable arm acts as a compensating organ disposed between the pulley (on which the yarn accumulates) and the voltage sensing organ (load cell) and able to compensate for a change in the power supply state. or absorption of the yarn as it passes between each state of absorption of the same by the textile machine. This is to keep the thread tension equal to a constant and predefined value even during each change of the state of its feeding to the textile machine.

The movable arm of the known solution is made with a spring (for example a spiral spring), the final part of which includes an eyelet (for example in ceramic) for the passage of the wire, to allow the arm to perform its compensator function. .

During the use of the compensating device, an operator provides for an adjustment (manual or electronic) of the spring force to ensure that its final part, on which the wire runs during the working phases, is on average at center of an angular sector of work. In this way, in the event of variations in absorption by the textile machine, one of the following situations may occur:

- during a sudden increase in absorption, which the pulley motor is unable to follow (compensate for) due to its limited dynamics, the compensating arm will lower, giving the motor time to accelerate and reducing the output voltage peak at the power supply; or - during an abrupt reduction of absorption, which the motor is unable to follow due to its limited dynamics, the compensating arm will rise, allowing the motor time to decelerate and reducing the loosening of the output voltage to the power supply.

Obviously the ability to compensate tension peaks and slackening of the wire is strictly linked to the dynamics of the system (spring force) and to the amplitude of the angular sector within which the arm can move.

It should also be noted that the precedence indicated above provides for the possibility of measuring the position of the compensating arm to be used by the power supply control electronics to increase or decrease the speed of the pulley, as well as the possibility of adjusting the force of the spring through an electric actuator to make its operation automatic, not requiring the operator to manually adjust the force.

This known solution, while operating in an optimal way, still has limitations, as indicated below.

The compensating device of the known system works in practice as a scale and the force of the spring is adjusted manually or automatically to make sure that its force is able to compensate for the tension of the wire fed to keep its final part in the center of the sector. angular motion. The lighter the spring (in terms of weight) the more its force is calculated correctly and the more the reactivity of the system increases. However, it is evident that the working tension limits which the device can work effectively are also associated with the spring force.

For example, if the spring is calibrated for medium-high tensions for a specific application (for example 10 g), its strength must be calculated accordingly; when, on the other hand, the working voltage is lower, the chosen force will appear as an operating limit of the device.

The major limitation of the known compensating device is therefore that of having to size the spring according to the desired working voltage, making the system not very flexible, or of requiring a different size of the spring by the operator or a different size of the entire device. compensation when the working voltage varies, which obviously is not always possible.

In addition, since the final part of the compensating arm is part of the spring, it too is subject to bending due to the strength of the wire and this makes the reading of its position not precise and therefore difficult to use as a predictive signal to anticipate the compensatory intervention. of the device as the yarn absorption state changes; it is also difficult to keep the spring in a specific position, since it is flexible.

Finally, the compensation capacity, in particular that during the loosening phase, is strictly linked to the length of the arm and the width of the angular sector; therefore this capacity is limited.

US4752044 relates to a wire feeding apparatus with electronic tension control. The apparatus comprises a casing on one side of which there is a rotating member on which a thread directed towards a textile machine is wound, said thread having previously cooperated with a braking member associated with said casing. At the exit of the rotating member, the thread passes into a fixed eyelet and subsequently into an eyelet placed at the end of a movable guide arm which forms an integral part of the known thread feeding apparatus; at the exit of the eyelet of said guide arm, the wire cooperates with another fixed eyelet before leaving the apparatus.

The wire guide arm is able to form a reserve of wire on the output side of the rotating member and therefore downstream of it when the wire feeding undergoes slowdowns due to a variation in the absorption of the wire by the textile machine.

The wire guide arm can be directly integral with an electric motor in direct current with permanent magnets contained in the casing of the apparatus or cooperate with a lever which is an integral part of the apparatus and moved by an electric motor inside said casing. . In both embodiments, an electro-optical signal transducer detects the angular position of the guide arm and emits a signal which is representative of the tension of the wire fed and at the same time of the angular position of that arm and therefore of the size of the supply reserve. wire created downstream of the rotating part.

The electric motor (in direct current) defines an electromagnetic control transducer which exerts an accurately predetermined and adjustable control force on the guide arm. The force is equal to the tension that the thread exerts on the guide arm eyelet.

This force can be adjusted by means of a potentiometer present in an electric circuit which includes a power supply that feeds the direct current motor. In this circuit a compensation signal is defined which is imposed on the control input of the aforesaid current supply, said signal being set (and therefore of constant value) so as to correspond to a specific voltage of the wire.

In this way, the power supply controls the direct current motor to define an equilibrium position of the guide arm which it is able to maintain when subjected to the action of the wire.

More particularly, in a normal operating condition, the guide arm assumes the particular angular position of equilibrium between two stop pins between which said arm can move angularly to a limited extent. The force exerted by the wire passing through the eyelet integral with the arm is balanced by the action of the direct current motor acting on the lever or on the arm itself.

In the event of a change in the thread feeding condition, such as a reduction in the use of the thread by the weaving machine, the guide arm moves angularly with respect to the initial equilibrium position so as to generate, through the aforementioned transducer, an electrical signal corresponding to the change in position. The signal is sent to a control device of the apparatus. This device acts on the power supply of an actuator that commands and controls the rotating member so as to intervene on the wire feeding speed until the guide arm returns to the predefined equilibrium position in which the wire tension is compensated by the command force exerted. by the lever acting on the aforesaid arm and generated by the electric motor coupled to it or is in equilibrium with the force generated directly on the movable arm by the motor which cooperates with it.

The known solution, therefore, through the movement of the guide arm is able to detect a variation in the condition of feeding the yarn which is compensated by a corresponding action on the rotating feeding member. In this solution, the guiding arm is directly or indirectly subjected to the action of an electric motor whose function is only to counterbalance the variation in tension of the thread in order to keep the guiding arm in the rest position. However, the guide arm and the actuator directly or indirectly cooperating with it, have a completely passive function since it is only the intervention on the actuator of the rotating member that allows this arm to maintain the position of equilibrium or of return to it after the arm has moved angularly between the fixed pins (integral with the casing of the apparatus). This guide arm is always subjected to a predetermined force and can only compensate for limited variations in the tension of the thread due to its limited movement between the aforesaid fixed pins.

WO2005 / 111287 discloses a thread feeding device comprising a sensor adapted to read the tension of the thread fed to a textile machine and a rotating feed member subject to the control of an electric motor. The movement of this member is commanded and controlled by a microprocessor unit adapted to regulate the speed of this member as a function of the thread tension detected by the tension sensor. This sensor is placed at the free end of a rigid arm, movable in contrast to a resistant element when the wire changes its tension at the output of the rotating member and passing over a roller or idle pulley associated with the free end of the movable arm. The contrast to the movement of this arm can be obtained by means of a spring or a carriage movable along a guide associated with the feeding device.

The rotating member and the movable rigid arm are an integral part of the known feeding device.

In working conditions, the wire winds at least once on the rotating member before passing through the pulley located at the end of the rigid arm. The movement of the wire causes the arm to rotate in a direction that follows the direction of feeding the wire and this rotation is opposed by the contrast elements (spring or carriage), an action regulated by an operator. The tension sensor detects the thread tension, compares it with a fixed value and then adjusts the speed of the rotating member so as to keep the thread tension close to the required value. The movement of the rigid arm prevents any excessively rapid increase in thread tension through its own folding thus avoiding thread breakage.

Also in this case, the movement of the rigid arm is limited within a predefined angular sector.

In both known solutions of the two precedents described above, the apparatus of US4752044 or the device of WO2005 / 111287 are integral elements with the compensation members and these are not separable or autonomously achievable. The result is a high manufacturing complexity of the known solutions, a great difficulty as regards the execution of any maintenance interventions and their high cost.

The purpose of the present invention is to offer an improved method and system for controlling the feeding of the yarn fed discontinuously and which comprises a yarn feeder to which a compensating device for the change in yarn absorption by the machine is associated. textile.

In particular, the object of the present invention is to offer a system of the type mentioned with a compensation device to be inserted inside an adjustment ring (voltage measured with respect to the speed of the feeding pulley) of the feeding of a wire to a textile machine that exceeds the limits of existing solutions.

Another object is to offer a method of the aforementioned type which can allow to compensate actively or dynamically any tension variation undergone by the yarn during the aforementioned discontinuous feeding to the textile machine both in the phases of feeding the yarn to the textile machine and during the withdrawal of the yarn from the latter in the phases in which this feeding is interrupted.

A further object of the invention is to provide an autonomous compensating device adapted to be used in a system of the aforementioned type which does not vary its dynamic characteristics as a function of the set working voltage, making the device flexible and easy to use.

Another object is to offer a compensating device of the aforementioned type which allows to have a precise measurement of the position of a compensator member and which can also operate in a predictive manner when the wire begins to undergo voltage variations at the beginning of a different phase. the state of discontinuous feeding to the textile machine.

A further object is to offer a compact compensator device which can also be applied as an additional element to a feeder which allows the system to which it belongs to recover more yarn during the loosening or reversal phases of the textile machine than known systems can recover. .

These and other objects which will be evident to the skilled in the art are achieved by a method, a feeding system and a compensating device according to the appended claims.

For a better understanding of the present invention, the following drawings are attached, purely by way of non-limiting example, in which:

Figure 1 shows a front view of a compensating device according to the invention associated with a known feeder device for controlling the tension of a thread fed to a textile machine;

figure 2 shows a side view of the devices of figure 1;

Figure 3 shows a perspective view of the compensating device according to the invention and of the power supply device of Figure 1;

figure 4 shows a front perspective view of the compensating device according to the invention;

figure 5 shows a side view of the compensating device according to the invention;

Figures 6 to 8 show the compensator device from above and in three different positions of use;

figure 9 shows a bottom view of the compensating device according to the invention; And

Figures 10A-10C show various block diagrams relating to the use of the system according to the invention;

Figures 11A-11C show graphs relating to curves of the tension of the yarn directed to the textile machine, respectively in the cases in which the device according to the invention is not operative (Figure 11A) and in two cases in which the system according to the invention operates passively -dynamic (Figure 11B) and active-predictive (Figure 11C).

With reference to the aforementioned figures (where corresponding parts have identical numerical references), and in particular to Figure 1, a compensating device according to the invention is generally indicated with 1 and is associated with an end 2A (or placed on a side) of a device feeder or simply feeder 2, per se known, able to feed a thread F (shown in broken line in figure 1) at constant tension to a textile machine T. The thread F can also be metallic and be sent to an operating machine such as a winder . The device 1 is a complete and easily identifiable element, both in terms of construction and use, with respect to the power supply 2.

The power supply 2 has a voltage sensor 3, a pulley 4 (or equivalent wire storage member) moved by its own electric motor (not shown) and a control unit or electronics 60 preferably with a microprocessor (see figure 10A -10C) and known in itself. This control unit or electronics is able to analyze the value of the tension of a thread detected by the sensor 3 during its feeding to the textile machine, compare the detected tension with a predetermined value (or SET POINT) and check and adjust the tension. of the wire (if different from the desired value) through an action on the aforesaid electric motor and therefore on the pulley 4. Said feeder 2 and its parts 3, 4 are of a per se known type and operation and therefore will not be further described.

The feeder, as said, allows to feed the thread to the textile machine with constant tension, said textile machine being able to be a production unit of manufactured articles or a machine for processing the yarn.

The device 1 and the feeder 2 define a yarn feeding system F according to the invention.

The compensator device 1, according to the invention, is able to cooperate with the yarn after it has passed over the pulley 4. This compensator device is therefore inside the yarn tension adjustment ring, as can be seen from the figure 1 and as will be evident with the description of the method according to the invention. Thanks to the present invention, the dynamic performance of the feeding system can be increased as the latter will be able to instantly compensate for sudden variations in the yarn absorption (positive and negative), allowing the pulley motor to reach the new speed to feed yarn as required by the new absorption situation without causing positive or negative tension peaks on the final yarn tension.

Furthermore, the presence of the compensator device 1 inside the adjustment ring always guarantees that the tension of the wire coming out of the feeder 2 is always the set one.

The compensator device 1 is an autonomous member with respect to the power supply 2 and comprises an electric motor 8, for example in direct current with brushes, preferably with very low inertia to increase its dynamics. In the embodiment of the invention given by way of example, the motor 8 moves a shaft having two parts protruding from opposite sides of the motor itself. In the figures, the first part is indicated by 7 (see figures 7-9), and the second shaft part indicated by 10 is visible in figure 9; the motor is also inserted inside a body 11 of the device. A rigid arm 13 is mechanically linked to the first part of the shaft, at the end 14 of which there is an annular (or other shaped) ceramic (or other material) body 16 on which the wire runs.

The electric motor 8, as mentioned, preferably has a very low inertia in order to allow a rapid movement of the arm 13 under the action of the wire, therefore a rapid compensation of this movement without the latter causing voltage peaks in the wire itself.

The arm 13 can however freely rotate around an axis M (or axis of the motor shaft) if dragged by the wire F whether the motor is at very low inertia (preferred) or if it has a limited inertia in any case; this arm, in any case, has a zero or initial rest position (for example the one visible in figure 6) which is assumed when the thread F is absorbed without variations in tension and without interruptions by the textile machine T. This arm it may also take other offsetting positions, as described below.

The arm 13 - motor 8 assembly (ie, essentially, the device 1) can operate in two different ways: passive-dynamic or active-predictive.

In the passive-dynamic mode, the motor allows the arm 13 to be dragged by the wire and moved from its rest position, but intervenes after this movement to bring it back to the rest position. In this mode or operating mode the motor essentially operates as a "dynamic" spring whose force (with which it acts on the arm 13) is programmable by programming and / or controlling the torque of the motor.

This force, however, is not predefined and fixed (as in the solution of US4752044), but is variable as it automatically adapts to variations in the setting of the thread tension in the various phases of the production process so as to always maintain the predefined position of the arm whatever. and the operating tension of the thread set in each particular production phase of an article. This allows the motor 8 to oppose a force equal to and opposite to that which moves the arm 13 from the rest position to keep this arm in its equilibrium position (for example that at "3 o'clock" of Figure 6).

The variability of the opposite force or of the intervention of the motor on the arm 13 will be described below.

In the active-predictive mode or mode, the motor 8 is able to intervene in advance (in "predictive" mode) at the first detection of a variation in the thread tension (detection carried out by the sensor 3) due to a modification of the operating phase of the machine. In this case, the motor 8 moves the arm 13 in advance towards the compensation position which is suitable for compensating the voltage variation: if this is in the direction of an increase, the motor 8 moves the arm towards the compensation position at "o'clock". 6 "of figure 7, if the variation is in the direction of a decrease in the thread tension (because the weaving machine has stopped or slowed down the thread withdrawal), the motor moves the arm 13 towards the compensation position at" 12 o'clock " of figure 8. This allows to keep the thread tension constant regardless of the operational and production phase of the textile machine T.

Figures 11A-11C show the voltage curves in the cases of motor-arm assembly or device 1 disabled (figure 11A), in passive-dynamic (figure 11B) or active-predictive mode (figure 11C).

In the figures, the curves or lines F, K, W and Y respectively define the set voltage of the wire (in an operating phase of production, curve F), the measured voltage of the wire (curve K), the set point position of the arm 13 (W curve) and the real position of arm 13 (Y curve). In the figures, time is on the abscissa, while the voltage value measured for F and K is on the ordinate, while a position value for W and Y.

As can be seen from the comparison of the figures, with device 1 disabled the measured yarn tension has significant peaks and variations if compared to the other cases of figures 11B, 11C. From the comparison of Figures 11B and 11C it can also be seen that the yarn tension has more limited variations in the case of intervention of the device 1 in active-predictive mode. Finally, from Figure 11C it can be seen that the rest position of the arm 13 (curve W) is not predefined, but follows the variation of the thread tension; this rest position is also "followed" by the "current" position of the arm during the compensation carried out by the device 1.

The second part 10 of the drive shaft supports a magnet 18, which, together with the arm 13 associated with the motor 8, is free to rotate around its axis M within a specific circular sector. Alternatively, the assembly consisting of the arm 13 and the magnet 18 can rotate freely, making a complete revolution around the axis of rotation M (axis of the drive shaft); in other words, both the arm 13 and the magnet 18 are keyed onto the motor shaft which, therefore, both rotate around the axis M in the same way, freely or within an angular sector.

Around the magnet, there are position detecting means 19, for example one or more linear Hall sensors 20, adapted to generate a position signal addressed, for example, to a control unit 70 of the compensator device 1. This unit 70 is able to transform (thanks to the data of the Hall sensors) the rotation of the motor into two sinusoids out of phase with each other by 90 ° (Sine and Cosine) from which it is possible to obtain in real time the absolute position of the shaft and therefore of the arm 13 which cooperate with the thread.

In one embodiment, the control unit advantageously comprises also systems (per se known) for driving the electric motor to control its rotation speed and the applied torque.

Preferably, a real-time data exchange is also provided between the control electronics 60 of the power supply 2 and the control unit 70 of the compensating device 1 in order to be able to set the desired torque to the motor of this device 1 and then check its rotation and read its position. The torque setting is dynamic and not fixed as it depends on the thread tension set or detected by sensor 3.

The exchange of information can take place through one of the following forms: through any serial bus, through digital or PWM signals, or through analog signals.

It is therefore evident that the power supply 2 (through its control electronics), which cooperates with said compensating device 1, is able to know in real time the position of the arm 13 and regulate the torque / displacement / speed applied to the motor of the compensator device 1.

By suitably managing the position signal of the arm 13 received and suitably controlling the motor acting on this arm, the wire feeding system F according to the invention is therefore able to close a second adjustment ring on the position of the arm 13 to keep it in the position desired, for example in its central position ("3 o'clock"), when the set voltage varies. This is in order to compensate the movement of the yarn and the variations in its tension linked to the various operating phases of the textile machine.

With reference to figures 10A, 10B, the system can be realized in different ways: 1. The compensator device 1 has its control unit 70 able to receive a rest position reference from the control electronics 60 of the power supply 2 ( indicated by block 80 in figures 10A and 10B) that the arm must maintain when the set or detected voltage of the wire F varies. The control unit 70 cooperates with the means (magnet 18) to measure the position of the arm 13 and to drive engine 8 (blocks 81 and 82). It is therefore this control unit that closes the ring for adjusting the position of the arm 13.

2. Alternatively and preferably, it is the control electronics 60 of the power supply 2 that receives the data relating to the position of the arm 13 from the magnet 18 and consequently sets a torque value to the motor 8 to close the adjustment ring. this position (based on the thread tension value set or detected). In this case, the driving means of the motor 8 may reside in the control unit 70 of the compensator device 1 (to which a reference is passed by the power supply) or in the electronics 60 of the power supply 2 (as described later). This solution is preferable because the control electronics 60 of the power supply 2, in addition to knowing the position of the arm, also directly knows the measured voltage of the wire (being connected to the voltage sensor 3) and can therefore use the two information to optimize the system performance. For example, if this electronics realizes that the thread tension is increasing due to a sudden thread request by the textile machine T, it can decide to automatically modify the position set point of arm 13, for example by moving it from "3 o'clock" "At" 6 o'clock ". This according to the active-predictive operating mode of the motor assembly 8-arm 13, indicated above.

This function also allows a further reduction of the voltage peak because not only the low inertia of the motor 8 is exploited but also its dynamics to compensate for the event. Obviously, the same thing is true in the phase of an abrupt slowdown in absorption. All this is in fact detectable from figure 11C and from its comparison with figure 11B previously commented.

The electronics of the power supply system (i.e. the control unit 70 of the compensator device 1 or the control electronics 60 of the power supply 2, as described above), continuing to read the position of the arm 13 (as a function of the voltage detected by the wire F) and by suitably controlling the torque of the motor which cooperates with the arm 13 is able to maintain the position of the compensating arm 13 at the desired value. This torque value will therefore allow the arm 13 to be kept in equilibrium in its rest position, for example at 3 o'clock by applying a force equal to and opposite to the power supply voltage of the wire. Therefore an increase or decrease in the thread tension will cause a displacement of the arm 13 from its equilibrium position, always keeping the thread at the set working tension, as for example indicated below: a) in the case in which the set thread tension should increase during processing, the arm 13 will obviously tend to lower (moving towards the "6 o'clock" position in figure 7) and the system electronics (i.e. the control unit 70 of the device 1 or the control electronics 60 of the power supply 2) by reading this position variation it will calculate the new torque to be applied to the motor 8 to bring the arm 13 back to the rest position;

b) in the event that the set voltage should decrease during processing, the arm 13 will obviously tend to rise (moving towards the "12 o'clock" position in figure 8) and the control unit or the electronics of the power supply reading this position variation will calculate the new torque to be applied to the motor 8 to return the arm 13 to the rest position.

The power supply electronics will therefore be able to control the position of the compensating arm 13, automatically and quickly, thus allowing the operator to change the working voltage at will, during processing, to perform, for example, graduations of tension during the production cycle of the product (for example graduated compression on medical stockings, ...). Each voltage variation involves a variation of the motor torque applied to the arm 13 which will always assume the rest position (for example "3 o'clock") or will be brought back to it to keep the "current" voltage of the wire constant, that is the voltage it assumes. the yarn during the particular feeding phase that occurs for the particular production phase.

In other words, the power supply system is provided with a control unit (of the device 1 or of the power supply 2), for example with a microprocessor, which controls the operation of the motor that moves the arm 13. This arm, however, together with the The motor shaft to which it is connected can initially move freely around the axis M when the state of absorption or power supply of the textile machine varies with a consequent variation in the tension of the thread which passes through the annular body 16 carried by the arm 13.

Any variation in the position of the arm 13 (with respect to a predefined reference or rest position, for example "3 o'clock") is detected by the control unit of the power supply system through the signals coming from the position detecting means 19. This data is supplied to said unit to the control electronics (60, 70) of the power supply system to close the regulating loop.

The control unit 70 of the device 1, in particular, can detect how much (angularly) the arm 13 has moved from the reference position and on the basis of this value the control electronics 60 of the power supply 2 can control, modify and controlling the power supply of the motor of the pulley 4 so that the latter modifies its rotation speed to compensate for the angular movement of the arm 13 with respect to the reference position. In this way the power supply 1 exploits the information relating to the position of the arm 13 to anticipate the event (acceleration / deceleration of the pulley 4), further improving the quality of the output voltage. This is done according to the "active-predictive" operating mode described above.

Also in this case, therefore (as in the case of EP2262940) the compensator device 1 behaves like a "scale" and the electronics of the power supply system will calculate in real time the torque to be applied to the motor 8 which cooperates with the arm 13 to always keep it in balance in a totally automatic way. This depends on the "current" tension of the wire F (obviously to maintain the predefined tension).

By controlling in this way the position of the arm 13, a compensation effect of the output voltage will also be obtained which will lead to a total elimination or drastic reduction of voltage peaks and slackening of the yarn itself. In fact: when the textile machine T increases its demand for thread F in an abrupt manner and the dynamics of the motor that drives the pulley 4 is not sufficient to compensate for this variation, the arm 13 will tend to lower (moving towards the "6 o'clock" position ) increasing the quantity of thread F sent to the machine T; this until the motor of the pulley 4 has reached the necessary rotation speed, eliminating or reducing the voltage peak. At this point the arm will return to its initial or resting position automatically.

On the contrary, when the weaving machine decreases its thread demand abruptly and the dynamics of the motor that controls the pulley 4 is not sufficient to compensate for this variation, the arm 13 will tend to rise (moving towards the "12 o'clock" position figure 8) by decreasing the quantity of wire to be sent to the machine T, until the motor of the pulley 4 has reached the necessary rotation speed, eliminating or reducing the slack in the wire. At this point the arm will return to its rest or initial position automatically (figure 6).

The rest position of the arm 13 in a first embodiment thereof is internal to a movement path of the compensating member or arm 13 having two limit positions (ie 6 hours 12 hours).

The electronics of the power supply 2 also knowing precisely and in real time the position of the compensating arm 13 can use this information to accelerate or reduce the rotation of the pulley 4 to minimize the settling time at the new ideal speed to have and maintain the tension of the thread F at a constant predetermined value, further limiting the amplitude of the tension peak of the thread F or its slackening.

The power supply system, knowing, moreover, precisely and in real time, the position of the compensator arm 13 and the value of the voltage measured through the sensor 3, during transients (absorption variations) can modify the driving of the motor 8 which cooperates with the arm 13 to make the output voltage variation of the power supply 2 still lower; for example:

i) during the sudden acceleration phase, the arm 13 will tend to lower (moving towards the compensation position "6 o'clock" of figure 7) and the measured thread tension will tend to rise; in this case the electronics of the power supply system could decide to:

1) interrupt the closing of the control ring of the position of the arm 13 or reduce its effect so that the thread can lower the arm 13 until the tension of the thread itself falls within the predetermined limits, thus using the space to move from 3 to 6 as a supply of wire to be fed;

2) automatically set a working setpoint of the arm 13 at a lower position to favor a greater quantity of yarn Z F to the textile machine T until the critical condition is overcome.

ii) during the abrupt deceleration phase, the arm 13 will tend to rise (moving towards the compensation position "12 o'clock" of figure 8) and the measured voltage to decrease; in this case the power supply system could decide to:

1) interrupt the closing of the position control ring or reduce its effect so that the arm 13 can recover the wire F until its tension is within the pre-established limits, thus using the space to move from 3 o'clock to 12 o'clock, acting as a recovery of excess fed yarn;

2) automatically set a working setpoint or rest position of the arm 13 to a higher position to favor a smaller quantity of thread F to the textile machine T until the critical condition is overcome.

The setpoint or reference value of the adjustment ring of the position of the compensator arm 13, up to now considered for example at the "3 o'clock" value (figure 6), could instead be variable and suitably managed dynamically by the power supply electronics, in order (for example) to favor a possible subsequent feeding phase: for example, during the slowdown phase and therefore stopping of the yarn by the textile machine, the setpoint could automatically switch to the 12 o'clock position in order to have, upon restarting, a greater supply of line that can be favored at the next acceleration, further reducing the next peak.

In a further embodiment of the invention (already present in the figures), associated with the compensating arm 13 there is also a drum or cylinder 26 on which to deposit the yarn during the recovery phase, thus increasing the quantity of stored yarn, since the amplitude of the angular sector of rotation, which in this case will no longer be limited from 6 to 12 o'clock, but will be able to rotate freely around the axis of rotation M.

The drum where the yarn is to be deposited can be integral with the arm 13 or free to rotate on bearings which make its rotation independent. The diameter of the drum determines the maximum quantity of yarn that can be recovered by the device system 1 - feeder 2. This drum can therefore have different dimensions depending on the quantity of yarn that is to be recovered on it. This drum can be cylindrical, semi-cylindrical or have a variable section shape.

The compensating device could work without mechanical stops, which prevent its rotation beyond 6 - 12 o'clock, allowing the arm 13 to rotate indefinitely around the axis in the recovery phase. In this case the arm 13 is free to deposit on the drum 26 a much greater quantity of yarn stored during the recovery phase, yarn which will then be re-fed to the textile machine at the next restart.

This determines a double "reservoir" of yarn, that is the drum 26 in addition to the pulley 4.

Thanks to the invention, a single "system" is able to work at supply voltages which are also very different from each other, without requiring any intervention by the operator. This system is able to compensate for sudden power variations without creating voltage peaks or slackening of the yarn, as well as, in limited dimensions, to recover quantities of yarn F higher than the solutions previously described in the state of the art.

Various embodiments of the invention have been described. Obviously still others are possible. For example, the annular ceramic body present on the arm 13 could be replaced by a body made of any other material with sliding characteristics suitable for the application. In addition, the text describes the use of a brushed direct current motor, but it is obvious that any type of electric motor or actuator (brushless, stepper ...) and even pneumatic one could be used.

In order to detect the rotation of the motor shaft, the use of an encoder with Hall sensors has been described, but any encoder on the market could also be used or it could be the same integrated inside the motor; in this case it is not necessary to have the crankshaft protruding on both its faces.

In addition, the arm 13 is rigid, even if it could be provided with its own flexibility, so as to further cushion the compensation effect, this flexibility deriving from the material or the section with which the arm is made. Furthermore, this compensating arm is described as being rotating, but could be replaced by an arm that follows a linear movement using a linear actuator, which moves longitudinally passing through the equivalent positions of 6, 3, 12 o'clock.

Finally, the existence of a control unit of the device 1 cooperating with the control electronics of the power supply 2 has been described. Obviously, this control unit could be that of the power supply 2 (i.e. being part of the control electronics of the latter) and intervene automatically when the body 11 of the device 1 is linked to the power supply 2, automatically recognizing the presence of the device 1 (the presence of the body 11 being detected by special connectors, not shown, through which the unit control unit cooperates with the motor of the device 1 and with the encoder or sensor means for the position of the motor shaft associated with the arm 13). This solution is shown in figure 10C.

The invention is applied to the feeding of textile but also metallic threads.

These variants are also to be considered included in the scope of the invention defined by the following claims.

Claims (16)

CLAIMS 1. Method for feeding at constant tension even metallic threads or yarns to a textile machine (T) or to a metal thread processing machine, said feeding taking place discontinuously or with sequences of phases in which the movement of the thread (F) occurs with at least one first and at least one second power supply or absorption state by the machine which are different from each other, said states following each other temporally, said power supply being carried out by a yarn feeder (2) having voltage sensing means (3), means yarn accumulators (4) moved by its own electric motor and control means (60) connected to said voltage sensing means (3) and accumulators (4) and able to intervene on said accumulator means (4) on the basis of a value voltage obtained by said voltage sensing means (3), a compensator device (1) associated with said feeder member (2) being provided, cooperating with the wire (F) output from d said accumulator means (4) before it cooperates with said voltage sensing means (3), said compensator device (1) being able to compensate for the modification of the power supply or absorption state of the yarn (F) as it passes between each first and each second power supply or absorption state consecutive to the first, this allowing the control means (60) of the feeder member to intervene on the accumulator means (4) in order to modify their action on the wire and keep the voltage value detected by the voltage sensing means (3) is equal to a set value, said constant voltage value being maintained even during the phase of changing the power state thanks to the interaction between said wire and said compensator device (1), the compensator device ( 1) comprising a movable compensating member (13) carrying at a free end a body (16) adapted to cooperate with the wire (F), said movable compensating member e.g. being able to move from a predetermined rest position in the direction of feeding of the yarn (F) when the latter passes from a state of lower absorption to one of greater absorption, but moving in the opposite direction when the yarn (F) passes from one state of greater absorption to a state of lesser absorption, said compensating member (13) returning to the rest position at the end of this change in absorption, characterized by the fact that it is foreseen to control and command the movement of said compensating member (13) through its own corresponding electric motor (8) as a function of the thread tension (F) set or detected and of the position measured during each phase of its feeding to the textile machine, said compensating member (13) being rigid. 2. Method as per claim 1, characterized by the fact that the compensating organ (13) and the relative electric motor (8) that commands and controls it in movement operate according to a passive-dynamic mode, said compensating organ (13) being able to move freely under the action of the wire (F) but being returned after this movement to the rest position by the electric motor (8), said motor (8) generating a torque capable of maintaining the rest position of said compensating member thread (F) when feeding the thread to the weaving machine. 3. Method according to claim 1, characterized in that the compensating member (13) and the relative electric motor (8) that commands and controls it in movement operates according to an active-predictive mode, said motor (8) moving said compensating member (13) from the rest position towards a compensation position corresponding to the variation in tension of the thread (F) as soon as this variation is detected. 4. Method according to claim 1, characterized in that a continuous control of the electric motor (8) of the compensating device is provided by a control unit (60, 70) connected directly or indirectly to the voltage sensing means (3 ). 5. Method according to claim 1, characterized in that it is provided, alternatively, that said compensating member (13) rotates around a fixed axis (M) or translates along the compensator device (1). 6. Method according to claim 1, characterized in that a further accumulation of yarn (F) is provided on the compensating device (1) in addition to the accumulation of yarn on the accumulator means (4) of the feeder member (2). 7. Method according to claims 1 and 5, characterized in that the movement of the compensating member (13) is alternatively limited angularly or unlimited angularly. 8. System for the constant voltage feeding of wires, including metallic ones or yarns, to a textile machine (T) or to a metal wire processing machine, said feeding taking place discontinuously or with sequences of phases in which the movement of the yarn (F) occurs with at least one first and at least one second state of feeding or absorption by the machine which are different from each other, said states following each other temporally, said feeding system operating according to the method of claim 1 and comprising a feeder member (2) of the thread having the voltage sensing means (3), thread accumulating means (4) moved by its own electric motor and control means (60) connected to said voltage sensing means (3) and accumulators (4) and adapted to intervene on said accumulator means (4) on the basis of a voltage value obtained from said voltage detection means (3), a compensator device (1) associated with said feeder member (2) cooperating with the wire (F) coming out of said accumulator means (4) before it cooperates with said voltage sensing means (3), said compensating device being able to compensate the modification of the power supply or absorption state of the thread (F) at the passage between each first and each second consecutive power or absorption state, this allowing the control means (60) of the feeder member to intervene on the accumulator means (4) in order to modify their action on the wire and keep the voltage value detected by the voltage detection means (3) constant over time and equal to a set value, said constant voltage value being maintained even during the phase of changing the power state thanks to the interaction between said wire and said compensating device (1), the compensating device (1) comprising a movable compensating member (13) able to move from a rest position provides balances in the direction of feeding of the yarn (F) when the latter passes from a state of lower absorption by the machine to a state of greater absorption, but moving in the opposite direction when the yarn (F) passes from a state of greater absorption to a state of lower absorption, said compensating member (13) returning to the rest position at the end of this change in absorption, characterized by the fact that said compensating member (13) is a rigid arm carrying an extremal body (16) adapted to cooperate with the wire (F), said rigid arm (13) being connected to its own electric motor (8) which commands and controls its movement according to the set or detected voltage of the wire (F), said rigid arm being arranged between said yarn accumulating means (4) and said tension sensing means (3); but being separate from the latter. 9. System according to claim 8, characterized in that alternatively the rest position of the compensating member (13) is internal to a path of movement of said compensating member having two limit positions or is defined within a circular path of said member around an axis (M), said path not being angularly limited. 10. System according to claim 8, characterized in that position detecting means (19) suitable for determining the spatial position of the rigid arm (13) are provided, said position detecting means (19) being associated with the driving shaft said electric motor carrying also said rigid arm. 11. System according to claim 10, characterized in that a control unit (60, 70) of the electric motor (8) of the compensating device (1) is provided, connected to the position detecting means (19) and able to detect the displacement of the compensator member (13) from the predetermined rest position through said position detecting means (19) and to return said compensator member (13) to the predetermined rest position by means of the command and control of the electric motor, said control unit ( 60, 70) being directly or indirectly connected to yarn tension detecting means (3), said control unit controlling and commanding the electric motor on the basis of the yarn tension value (F) detected during the feeding of said yarn ( F) to the machine. 12. System according to claim 11, characterized in that said control unit (60, 70) is alternatively associated with the compensating device (1) and connected to the control means of the feeder member (2) or said control unit is part of the control means of the feeder member (2). 13. System according to claim 8, characterized in that said compensating device (1) is removably fixed to the feeder member (2) and / or is placed at one end (2A) or on a side of said feeder member, said compensator device (1) being completely automatic with respect to said feeder member (2) but being intimately connected to said feeder member when connected thereto. 14. System according to claim 8, characterized in that said compensating device (1) has a member (26) rotating around its own axis and able to receive, in winding, the wire (F) in at least one of said states power supply or absorption of the machine. 15. Compensating device adapted to be used with a constant tension feeder (2) of metal threads or yarns (F) to a textile machine (T) or to a metal thread processing machine, called feeder organ (2) comprising tension sensing means (3) of said yarn (F), and accumulating means (4) of the yarn itself, said machine operating discontinuously, said compensator device (1) and said feeder member (2) defining a feeding system according to claim 8 operating according to the method of claim 1, said compensating device (1) having a compensating member (13), movable and able to cooperate with said wire (F) before it leaves said feeding member (2), characterized by the fact that said compensating member (13) is defined by a rigid arm associated with means for actuating its movement, said rigid arm cooperating slidingly with the wire (F) and being placed between said accumulating means (4) and said tension sensing means (3) of the feeder member (2), said tension sensing means (3) being separated from said rigid arm (13), accumulating means (4) of the yarn itself, the rigid arm being able to move from a predetermined storage position in the direction of feeding the yarn (F) when the latter passes from a state of less absorption by the machine to a state of greater absorption, but moving in the opposite direction when the yarn ( F) passes from a state of higher absorption to a state of lower absorption, being provided for position detecting means (19) suitable for detecting the displacement from said rest position, said position detecting means (19) being connected to a unit of command and control adapted to detect directly or indirectly the tension of the thread (F) and to command said actuator means on the basis of the tension set or detected in order to bring said rigid arm back to the position of rest after moving from the latter. 16. Compensating device according to claim 15, characterized in that it comprises a rotating member (26) adapted to receive the yarn thereon when the machine is stopped or in the phase of returning the yarn to the feeding process.