RS65791B1 - Method and yarn feeder system for optimising yarn feed to a textile machine operating highly discontinuously or with alternating motion - Google Patents

Description

The subject of this invention is the procedure for bringing the yarn to the machine, which processes it in accordance with the pre-characterizing clause of the main claim. A system according to the precharacterizing clause of the corresponding independent claim is also a subject of the invention.

Yarn distributors with constant tension (tension) have been known for a long time, which are used to feed yarn or wire to a textile machine, either to produce a finished product (e.g. a knitted item or socks) or to process that yarn, possibly in combination with other yarns (e.g. yarn preparation machines for subsequent use).

In particular, such yarn feeding devices are known which can feed yarns (including metal wires) or (textile/technical) yarns at constant tension. The mentioned devices work in accordance with the well-known principle of closed-loop control, which is implemented through the well-known yarn distributor with constant tension. The control procedure ensures that the yarn or wire is regularly fed at a constant tension, regardless of the speed of feeding said yarn and also regardless of changes in yarn tension at the entrance to said constant tension yarn distributor; all this applies whether the changes in tension are caused by the gradual emptying of the spool with yarn or by tearing or additional tightening caused by the irregular unwinding of said yarn.

A well-known constant tension yarn distributor, of the type mentioned above, is for example the subject of patent EP1492911 by the same applicant; this preceding text describes a distributor comprising a tension sensor, an actuator or motor acting on a feed pulley or belt and a control unit (or electronics) capable of evaluating the yarn tension, measured by said sensor, by comparing it to a desired operating tension (or SET POINT). Based on this comparison, the control unit acts on the motor, so it acts on the belt connected to it, braking or feeding the yarn, thus modifying or maintaining the tension of the yarn fed to the textile machine (for the production of the finished product or the processing of the yarn itself).

Devices and systems (and the procedures they apply) are also known, which are intended for feeding the yarn into the textile machine discontinuously or in a manner according to which the yarn moves with at least one first or at least one other condition for being brought into the textile machine or taken over by the textile machine, and which differ from each other. These different ways of bringing follow each other over time.

For example, a constant tension yarn distributor is known which contains devices, for example a measuring cell, which can measure the tension of the controlled yarn in real time, a belt on which the yarn is wound, with one or more windings, an electric motor which drives the belt to rotate and control electronics which, depending on the tension of the measured yarn, regulates the rotational speed of the motor and consequently of the belt, in order to keep the measured tension at a predefined and programmable value, which may be a function of the operating phase of the textile machine. The rotation of the motor is generally controlled in two directions, the first to feed the yarn into the machine, and the second to take it out of the machine during the stop or change of direction phases, to prevent the yarn from becoming loose and to keep it always at the desired tension.

With distributors of this type, the yarn is taken from the spool directly from the device and wound onto the belt. Obviously, in order to ensure a continuously good quality of controlled tension, there must be no slippage between the yarn and the belt; in fact, only in this case the control electronics can precisely calculate the speed that should be given to the motor, connected to the belt, in order to keep the tension at the desired value.

In applications where the take-up speed by the machine is constant, or without major discontinuities, this type of distributor can keep the measured tension constant, when the feed conditions change (variable yarn tension at the distributor entrance, feed speed changes, etc.). Obviously, since there is no slippage, in these operating conditions the distributor can keep the measured tension perfectly in line with the set value and at the same time accurately measure the amount of yarn supplied, which is the next fundamental parameter to ensure the quality of the finished product.

However, known solutions of the type mentioned above have performance limitations when the download speed of the machine changes abruptly. In applications of this type, the speed at which the textile machine picks up the yarn changes very quickly, for example, after selecting the needles in the knitting machine; in this case, if the motor turning the belt does not have the necessary output dynamics to follow these take-up changes, there is a maximum of yarn tension when the take-up speed increases, and a relaxation of the yarn when the take-up speed decreases.

Both of these defects in tension control (peaks and relaxation) can cause problems related to the quality of manufactured garments (presence of stop marks due to improper tension during processing) or lead to yarn breakage (due to maximum tension) or yarn falling from the working device (such as the needle) of the textile machine (due to relaxation).

Obviously, the problem is greater the smaller the elasticity of the yarn, which helps to compensate for the insufficient dynamic response of the motor.

Different solutions to this problem are known: for example, a distributor system containing a compensating device, which is connected upstream of the feeding point (of the type described above) and which, acting together with the yarn, helps to overcome the limitations described above, is known from patent EP2262940, by the same applicant. After the yarn is wound onto the distributor belt, the system requires that it be routed to the compensator's movable arm and then routed to the distributor's load cell. In this way, a compensating device is located inside the control loop (tension is measured in relation to the speed of the distributor belt) to ensure that the yarn tension remains constant when the position of the movable arm is changed.

In other words, according to the above-mentioned previous document, the movable arm acts as a compensating device, placed between the belt (on which the yarn accumulates) and the tension detection device (measuring cell) and can compensate the influence of changes in the conditions under which the yarn is fed or taken up, when passing through all the conditions under which it is taken up by the textile machine. This is to keep the yarn tension at a constant, pre-defined value, even with any changes in the conditions under which it is fed to the textile machine.

The movable arm of the known solution is constructed with a spring (for example, a spiral spring), the end part of which contains an eyelet (for example, ceramic) for the passage of the yarn, to enable the arm to perform its compensatory role.

When the compensating device is in use, the operator adjusts the spring force (manually or electronically) so that its end part, through which the yarn passes during the working phases, is on average in the center of the angular working sector. In this way, if there are changes in the takeover by the textile machine, one of the following situations may arise:

- during the sudden acceleration of the download, which the belt motor cannot follow (compensate), due to its limited dynamics, the compensating lever will fall, giving the motor enough time to accelerate and reduce the peak voltage at the distributor output; or

- during a sudden deceleration of the download, which the engine cannot follow, due to limited dynamics, the compensating lever will rise, giving the engine enough time to slow down and reduce the tension relaxation at the distributor outlet.

Obviously, the ability to compensate for tension peaks and yarn relaxation is closely related to the dynamics of the system (spring force) and the amplitude of the angular sector within which the handle can move.

It should also be noted that the previous document mentioned above foresees the possibility of measuring the position of the compensating lever, which is used by the control electronics of the distributor to increase or decrease the speed of the belt, as well as the possibility of adjusting the force of the spring using an electric actuator, in order to do it automatically, without the need for the operator to adjust the force manually.

This known solution, although it works extremely well, still has limitations, as will be noted below.

The compensating device of the known system in practice acts as a balance and the spring force is adjusted manually or automatically, to ensure that this force can compensate the tension of the supplied yarn to keep its end in the center of the angular displacement sector. The lighter the spring (in terms of weight), the more correctly its force can be calculated and the more it will increase the responsiveness of the system. However, it is clear that the spring force is also related to the limits of the operating tension under which the device can operate effectively.

For example, if a spring is calibrated for medium-high tension, for a specific application (eg 10 g), its force must be adequately calculated; when, instead, the operating voltage is low, the selected force will constitute the operating limit of the device.

Therefore, the known compensating device has a major limitation in that the spring must be dimensioned according to the desired working tension, which makes the system inflexible, or that the spring must be differently dimensioned by the operator, or that the entire compensating device must be differently dimensioned when varying the working tension, which of course is not always possible.

In addition, since the end of the compensating arm is part of the spring, it is also subject to bending due to the force of the yarn, which makes the reading of its position inaccurate and therefore difficult to use as a predictive signal to predict any compensatory action by the device, to change the conditions under which the yarn is taken up; it is also difficult to keep the spring in a certain position because it is flexible.

Finally, the ability to compensate, especially during the relaxation phase, is closely related to the length of the arm and the amplitude of the angular sector; therefore, this ability is limited.

US4752044 relates to a yarn distributor with electronic tension control. The device consists of a housing, on one side of which is placed a rotating element on which the yarn is wound which is directed towards the textile machine, wherein said yarn previously acted together with the braking means, which is connected to such housing. At the exit from the rotating element, the yarn passes through a fixed eyelet and then through an eyelet located at the end of the movable guide/arm, which forms an integral part of the known yarn distributor; at the exit from the eye of this guide, the yarn works together with another fixed eye, before leaving the device.

The purpose of the yarn guide is to form a reserve of yarn F on the output side of the rotating element and therefore downstream of it, when the yarn supply slows down, due to a change in the speed of yarn take-up by the textile machine.

The yarn guide can be directly connected to a direct current electric motor with permanent magnets, which is located in the housing of the device, or it can work together with a lever, which is an integral part of the device and is driven by an electric motor inside the mentioned housing. In both solutions, the electro-optical signal converter detects the angular position of the guide and emits a signal that represents the tension of the supplied yarn and at the same time represents the angular position of such a guide, and therefore the size of the yarn reserve, which is created downstream of the rotating element.

An electric motor (direct current) forms an electromagnetic control transducer that applies a carefully defined and adjustable control force to the guide. The force is equal to the tension with which the yarn acts on the guide eye.

This force can be adjusted using a potentiometer in the electrical circuit, which contains a DC motor power supply unit. In this circuit, a compensating signal is defined which is applied to the control input of said power supply, wherein said signal is adjusted (and therefore has a constant value) to correspond to the specific tension of the yarn.

In this way, the power unit controls the DC motor to define an equilibrium position of the guide, which can be maintained when subjected to yarn force.

More specifically, under normal operating conditions, the guide occupies a certain equilibrium angular position between two stop wedges (stops), between which the handle can only move angularly. The force exerted by the yarn when passing through the eye connected to the handle is balanced by the force exerted by the direct current motor on the lever or the handle itself.

In the event of a change in yarn feeding conditions, such as a reduced use of yarn by the textile machine, the guide moves angularly, relative to the initial equilibrium position, so that, via the above-mentioned transducer, an electrical signal corresponding to the change in position is generated. The signal is transmitted to the element for controlling the device. This element acts on the feed of the actuator that controls the rotating element, so that it acts on the yarn feed speed, until the guide returns to a predefined equilibrium position in which the tension of the yarn is compensated by the control force with which the lever acts on the aforementioned guide, which is generated by the electric motor connected to that lever, or is in balance with the force that the motor generates directly on the guide with which it acts together.

Thus, through the movement of the guide, the known solution can detect a change in the yarn feeding conditions, which is compensated by the appropriate action of the rotating feeding device. In this solution, the guide is directly or indirectly subjected to the action of an electric motor, whose function is only to compensate for the change in yarn tension, in order to keep the guide in a position of rest. However, the guide and the actuator, which directly or indirectly acts with it, have an exclusively passive role, because only the action of the rotating element on the actuator allows the guide to remain in the equilibrium position, or to return to the same position, after it has been angularly moved between the fixed pins (connected to the device housing). Such a guide is always under the action of a predefined force and can only compensate for limited changes in yarn tension, due to its limited movement between these fixed pegs.

WO2005/111287 describes a yarn distributor comprising a sensor capable of reading the tension of yarn fed to a textile machine and a rotating feed element controlled by an electric motor. The movement of this element is controlled by a microprocessor that regulates the speed of this element in accordance with the tension of the yarn, detected by the tension/tension sensor. The sensor is located at the free end of a rigid arm, which can be moved against a resistance element, when the yarn changes its tension at the exit from the rotating element and passes over a free roller or belt connected to the free end of the movable guide. Resistance to the movement of this guide can be provided by means of a spring or a carriage that moves along a rail connected to the distributor.

The rotating element and the movable rigid lever are integral parts of the well-known distributor. In working conditions, the yarn is wound at least once on the rotating element, before passing through the belt at the end of the rigid arm. The movement of the yarn causes the handle to rotate in the direction that follows the direction of the yarn feeding, and opposing elements (spring or trolley) act against this rotation, and their action is regulated by the operator. The tension sensor detects the yarn tension, compares it to a fixed value and then adjusts the speed of the rotating element to keep the yarn tension at the desired value. The movement of the rigid arm prevents any sudden increase in yarn tension by moving backwards, thus preventing yarn tearing.

As mentioned, the movement of the rigid arm is limited to a predefined angular sector.

In both known solutions, from the two previous documents described above, the device from US4752044 or the device from WO2005/111287 are elements incorporated into the compensating device and are not separable, nor can they be constructed independently. The result is a high level of complexity of the implementation of the mentioned solutions, great difficulties in performing any maintenance work, as well as high costs.

WO 2013/064879, on behalf of the applicant, describes the procedure and system in accordance with the precharacterizing parts of the corresponding independent claims of the subject document.

The previously mentioned previous document describes a device for feeding a metal wire, which consists of a body with an element for braking the wire, one or more belts, controlled by appropriate motors, on which the wire is wound, a wire passing through a compensating element and a tension sensor, before it reaches the operating machine. The control electronics can continuously measure the tension of the wire, in order to adjust it to a predefined value by acting on the first control loop, which acts on the motors and the second control loop, which acts on the compensating element.

This compensating element also contains a compensating lever having a free end, which acts together with the wire and rotates freely about a pin fixed to a holder which is connected to the body. This lever can then be moved within the body within a predefined angular sector, moving closer or further away from the tension sensor (defined by the load cell).

The compensating lever is connected to a spring connected on one side to a holder fixed to the body of the device, and on the other side to the compensating lever by means of a mobile cart, which is moved, via an Archimedean or endless screw, by means of a stepping electric motor.

Therefore, the compensating lever is not directly connected to the electric motor, but it drives and drives the compensating lever through the interposition of other components, each of which has its own inertia.

The compensating lever is connected to a position sensor that is connected to the control unit, which can therefore measure the position of the lever within a predefined angular sector.

Thus, the compensating lever can resist the slippage of the wire not statically, but dynamically: the control unit can actually vary the position of the trolley (by acting on the electric motor) to which the spring is connected, changing the force acting on the lever and bringing it to the desired position within a predefined angular sector. In this way, the compensating arm keeps the wire always perfectly tensioned on the measuring cell or tension sensor, especially during the phases when the wire is not fed to the textile machine.

The compensating arm also creates a reserve of metal wire, from which the machine can draw during unforeseen speed changes.

The aforementioned document then describes a distribution device that is equipped with a compensating lever, as an integral and inseparable component, which can move freely within a pre-defined angular sector.

The control system for the device knows the position of the handle and through the electric motor and the system (one or more) springs can define the force that is applied, in accordance with the measured voltage or the read position, thus closing two possible control loops, where the second loop refers to the tension (the first refers to the motor connected to the belts) and possibly another one for the position of the handle.

However, it should be noted that the force applied to the lever is controlled by a system of springs and a control trolley, which drives a stepper electric motor, which is used to change the fulcrum of the lever and thus the force acting on the wire.

Even in this previous document, the problems highlighted in connection with the system described in the above-mentioned EP 2262940 still apply.

In fact, the possibility of compensating the peaks of tension and relaxation of the wire, the device that is the subject of WO 2013/064879, is closely related to the dynamics of the system (spring force, moving carriage and motor) and the amplitude of the angular sector within which the compensating arm can move.

Further, even in this previous document the compensating arm practically acts as a balance and the spring force is automatically adjusted so as to compensate for the tension of the wire which is fed to keep its end in the center of the angular displacement sector.

Finally, the ability to compensate, especially during the relaxation phase, is closely related to the length of the compensation arm and the amplitude of the angular sector; therefore this ability is limited.

In addition, the known distribution device inextricably incorporates a compensating element. The result is a heavy assembly of significant dimensions.

The object of the present invention is to provide an improved method and system for controlling discontinuous yarn feeding, which includes a yarn distributor connected to a device that compensates for changes in the rate of yarn acceptance by the textile machine.

In particular, the objective of the present invention is to provide a system of the mentioned type with a compensating device that is inserted into the control loop (of tension measured in relation to the speed of the feeding belt) when the yarn is fed into the textile machine, which overcomes the limitations of existing solutions.

Another objective is to provide a process of the above-mentioned type that can actively or dynamically compensate for any change in yarn tension, during the previously mentioned discontinuous feeding into the textile machine, both during the phase of feeding the yarn into the textile machine, and during the phase of removing the yarn from the textile machine, where interruptions occur during those phases.

A further object of the invention is to provide a system of the above-mentioned type, which has an independent compensating device whose dynamic characteristics do not vary in relation to the set operating voltage.

Another object is to provide a system of the above-mentioned type, which has a compensating device that allows accurate measurement of the position of the compensating elements and can also work in a predictive manner when the yarn tension starts to change, at the beginning of the different phases of the discontinuous feed into the textile machine.

A further objective is to provide a system of the above-mentioned type, which has a compact compensation device that can also be applied as an additional element of the distributor, which allows the system to which it belongs to recover more yarn during the phases of relaxation or change of direction of movement of the textile machine, compared to the amount that can be recovered by known systems.

These and other goals, which will be evident to experts, are achieved by means of the distributor's procedure and system in accordance with the accompanying requirements.

In order to facilitate the understanding of the subject invention, purely as non-limiting examples, the following drawings are attached:

Figure 1 is a front view of a system according to the invention, comprising a compensating device, connected to a known distributor, for controlling the tension of yarn fed to a textile machine;

Figure 2 is a side view of the system shown in Figure 1;

Figure 3 is a perspective view of the system shown in Figure 1;

Figure 4 is a front perspective view of a compensation device used in a system according to the invention;

Figure 5 is a side view of the compensation device of Figure 4;

Figures 6 to 8 show the compensating device from above, in three different working positions; Figure 9 is a bottom view of the compensation device of Figure 4; and

Figures 10A-10C show various block diagrams relating to the use of a system in accordance with the invention;

Figures 11A-11C show yarn tension graphs, directed to the textile machine, in a situation where the compensation device of the system that is the subject of the invention is not in operation (figure 11A) and in two situations where the system according to the invention works in passive-dynamic mode (figure 11B) and active-predictive mode (figure 11C), respectively.

Referring to the previously mentioned drawings (where the corresponding parts have the same identification reference numbers), and in particular to drawing 1, the compensating device is generally indicated as 1 and is connected to the end 2A (or placed at the side) of the distribution device, or simply distributor 2, which is known per se, for feeding the yarn F (shown as a broken line in drawing 1) with constant tension into the textile machine T. The yarn F can also be a metal wire. and can be fed into a working machine such as a winding machine. Device 1 is a complete and clearly recognizable element, both in terms of construction and use, in relation to distributor 2.

The distributor 2 has a tension sensor 3, a belt 4 (or equivalent yarn accumulation device) which drives its own electric motor (not shown) and a control unit or electronics 60, preferably with a micro-processor (see drawing 1 10A-10C), which is known per se. This control unit or electronics can evaluate the yarn tension/tension detected by the sensor 3, when feeding it to the textile machine, compares the detected tension with a predefined value (or SET POINT value) and checks and adjusts the yarn tension (if it differs from the desired value) by the action of the mentioned electric motor and thus the belt 4. This distributor 2 and its parts 3, 4 are of a type and mode of operation that are known and therefore will not be further described.

The distributor, as mentioned, allows the yarn to be fed into a textile machine with a constant tension, said textile machine being a finished goods production unit or a yarn processing machine.

Device 1 and distributor 2 define a yarn feeding system F according to the invention. The compensating device 1 can act together with the yarn, after it has passed over the belt 4. Therefore, this compensating device is in the yarn tension control loop, as can be seen from drawing 1 and as will be clear from the description of the method according to the invention. Thanks to the present invention, it is possible to improve the dynamic performance of the distributor system, so that it can instantly compensate for sudden changes in yarn take-up speed (positive or negative), allowing the belt motor to change speed to bring the yarn in line with the new take-up conditions, without causing positive or negative peaks in the final yarn tension.

The presence of the compensation device 1 in the control loop always ensures that the tension of the yarn leaving the distributor 2 is always equal to the set value.

The compensator 1 is an independent device in relation to the distributor 2 and contains an electric motor 8, for example a DC motor with brushes, preferably of very low inertia, in order to increase its dynamics. In the solution given as an example, the motor 8 directly drives the drive shaft, which has two parts, coming out from opposite sides of the motor. In the drawings, the first part of the drive shaft is marked with number 7 (see drawings 7-9), and the second part, marked with number 10, can be seen in drawing 9; the motor is also inserted into the housing 11 of the device. The rigid lever 13 (which is thus attached to the drive shaft itself) is mechanically connected to the first part of the drive shaft. At the end 14 of the handle 13 there is a ring (or some other shape) body 16 made of ceramics (or other material) over which the yarn passes.

The electric motor 8, as mentioned, preferably has a very low inertia to allow a rapid movement of the lever 13 under the action of the force of the yarn and thus a rapid compensation of this movement without causing tension peaks in the yarn itself.

However, the lever 13 can freely rotate (causing the motor to rotate) about the axis M (or the axis of the drive shaft), if pulled by the thread F, whether the motor has a very low inertia (preferable) or has a limited inertia; in any case, this lever has a zero or initial rest position (for example, the position shown in drawing 6) which is taken when the textile machine T takes up the yarn F, without changing its tension and without breaking. This lever can also assume other compensating positions, as described below.

The handle 13 and motor 8 assembly (ie, the core device 1) can operate in two different modes: a passive-dynamic mode or an active-predictive mode.

In passive-dynamic mode, the motor allows the lever 13 (attached to the drive shaft) to be pulled by the yarn and move from its rest position, also causing the motor itself to rotate. However, this motor acts after said movement to return the lever 13 to the rest position. In this mode, or operating mode, the motor essentially operates as a "dynamic" spring, the force of which (acting on the lever 13) can be programmed by programming and/or controlling the motor's torque.

However, this force is not predefined and fixed (as in the solution from US4752044), but can vary by automatically adapting to changes in the set value of the yarn tension, in different stages of the production process, so that the handle is always maintained in a predefined position, whatever the set working tension of the yarn, during each specific stage of production of the final product. This allows the motor 8 to oppose with an equal but opposite force, the force that moves the lever 13 (to which it is always directly connected) from the rest position, to maintain this lever in an equilibrium position (for example, the "3 o'clock" position shown in drawing 6).

The variability of the counterforce, or motor action on the lever 13, will be described below.

In the active-predictive mode, the motor 8 can act in advance (in the "predictive" mode), as soon as a change in the yarn tension (detected by the sensor 3) due to a change in the working phase of the machine is detected. In this case, the motor 8 moves the handle 13, which is carried by the drive shaft, to a compensation position, capable of compensating for the change in tension: if it increases, the motor 8 moves the handle to the compensation position "6 o'clock", from drawing 7, and if the yarn tension decreases (because the textile machine stopped or slowed down the acceptance of the yarn), the motor moves the handle 13 to the compensation position "12 o'clock", from drawing 8. keeps the yarn tension constant, regardless of the working and production phase of the textile machine T.

Figures 11A-11C show tension curves in a situation where the motor-lever assembly or device 1 is inactive (Figure 11A), in passive-dynamic mode (Figure 11B) or in active-predictive mode (Figure 11C).

In these drawings, the curves or lines F, K, W and Y, respectively, define the set yarn tension (in the productive working phase, curve F), the measured yarn tension (curve K), the set position of the lever 13 (curve W) and the actual position of the lever 13 (curve Y). In these drawings, time is on the abscissa, and the ordinate is the measured tension for F and K, as well as the position for W and Y.

As can be seen by comparing the drawings, when the device 1 is inactive, the measured yarn tension has significant peaks and variations compared to other situations, from drawings 11B, 11C. By comparing Figures 11B and 11C, it can also be seen that the yarn tension has more limited variations in situations where the device 1 operates in active-predictive mode. Finally, in drawing 11C it can be seen that the rest position of the lever 13 (curve W) is not predefined, but follows the changes in the yarn tension; also, the rest position is "followed" by the "current" position of the handle, during the compensation performed by device 1.

The second part 10 of the drive shaft supports a magnet 18, which together with the lever 13, connected to the motor 8, can freely rotate around its axis M, within a certain circular sector (causing rotation of the drive shaft). Alternatively, the assembly consisting of the lever 13 and the magnet 18 can rotate freely, performing a complete revolution around the axis of rotation M (axis of the drive shaft); in other words, both the lever 13 and the magnet 18 are splined to the drive shaft, with the result that they both rotate in the same way around the axis M, freely or within the angular sector. This allows the position of the handle 13 to be instantly known, by detecting the position with the help of a magnet.

For this purpose, position detectors 19 are placed around the magnet, for example one or more linear Hall sensors 20, which can generate a position signal that is sent, for example, to the control unit 70 of the compensation device 1. Thanks to the data from the Hall sensor, this unit 70 can transform the rotation of the motor into two sinusoids with a distance of 90<o> (sine and cosine) from which, in real time, the absolute position of the shaft can be obtained, and thus lever 13, which acts together with the yarn, whereby the lever 13 is firmly connected to the shaft and the magnet 18.

In one solution, the control unit also usefully contains systems (known per se) that drive the electric motor and control its rotational speed and applied torque.

It is also desirable to provide real-time data exchange between the control electronics 60 of the distributor 2 and the control unit 70 of the compensating device 1, so that the desired torque of the motor of this device 1 can be set, and then its rotation can be controlled and the position can be read (and consequently, in a direct and instantaneous way, the levers 13). The setting of the torque is dynamic and not fixed, because it depends on the set yarn tension or the tension detected by sensor 3.

Information can be exchanged in one of the following ways: over any serial bus, over digital or PWM signals, or over analog signals.

Therefore, it is clear that the distributor 2 (by means of its control electronics), acting together with the said compensating device 1, can know the position of the lever 13 in real time, in a safe and instantaneous way, and can adjust the torque/displacement/speed applied to the motor of the compensating device 1. This is possible because of the direct connection between the drive shaft and the said lever, or because of the direct action of this motor on the lever.

By adequately managing the received signal of the position of the lever 13 and adequately controlling the motor acting on this lever, the yarn distributor system F, according to the invention, can close the second control loop for the position of the lever 13 almost instantaneously, to keep it in the desired position, for example in its central position ("3 o'clock"), during changes in the set tension. The aim of this is to compensate for yarn movement and changes in its tension associated with the different working phases of the textile machine.

Referring to drawings 10A, 10B, the system can be implemented in different ways: 1. The compensating device 1 has its own control unit 70, which is designed to receive from the control electronics 60 of the distributor 2 the reference rest position (indicated as block 80 in drawings 10A and 10B) that the handle must maintain during variations of the set or detected yarn tension F. The control unit 70 works together with element (magnet 18) for measuring the position of the levers 13 and the drive motor 8 (blocks 81 and 82). Therefore, the control unit closes the control loop for the position of the handle 13.

2. Alternatively and preferably, the control electronics 60 of the distributor 2 receives data related to the position of the lever 13 from the magnet 18 and consequently sets the value of the torque of the motor 8, to close the control loop for that position (based on the set or detected yarn tension). In this case, the driving element of the motor 8 can be located in the control unit 70 of the compensation device 1 (to which the reference is transmitted by the distributor) or in the electronics 60 of the distributor 2 (as described below). This solution is desirable, because the control electronics 60 of the distributor 2 not only know the position of the handle, but also directly know the measured yarn tension (which is connected to the tension sensor 3) and can use these two pieces of information to optimize the performance of the system. For example, if such electronics detects an increase in yarn tension, due to a sudden demand for yarn by the textile machine T, it may decide to automatically change the set point of the position of the lever 13, for example by moving it from the "3 o'clock" position to the "6 o'clock" position. This is consistent with the active-predictive mode of operation of the motor 8 and lever 13 assembly indicated above.

This feature also allows for further reduction of peak tension, as not only the low inertia of the motor 8 is used, but also its dynamics to compensate. Obviously, the same goes for the slow download phase. All of this can actually be seen from Figure 11C and by comparison with the previously mentioned Figure 11B.

The electronics of the distributor system (i.e. the control unit 70 of the compensation device 1 or the control electronics 60 of the distributor 2, as described above), by continuing to read the position of the lever 13 (which depends on the detected yarn tension F) and by appropriate control of the torque of the motor acting together with the lever 13, can maintain the position of the compensation lever 13 at the desired value. This torque value will therefore allow the handle 13 to be kept in balance, in its rest position, for example the "3 o'clock" position, by applying a force equal and opposite to the threading tension in the handle, directly across the drive shaft. This takes place without any delay in the actuation of the lever 13, as in contrast occurs in the solution of WO 2013/064879.

Thus, increasing or decreasing the yarn tension will cause the lever 13 to move from the equilibrium position, always maintaining the set working yarn tension, as indicated below:

a) in the case when it is necessary to increase the set yarn tension during processing, the handle 13 will obviously tend to fall (movement towards the "6 o'clock" position, from drawing 7), and the system electronics (i.e. the control unit 70 of the device 1 or the control electronics 60 of the distributor 2) which reads this change in position, will calculate a new torque to be applied to the motor 8 in order to return the handle 13 to the rest position; b) in the case when it is necessary to reduce the set tension during processing, the handle 13 will obviously tend to rise (moving towards the "12 o'clock" position, from drawing 8), and the control unit or distributor electronics, which reads this change in position, will calculate a new torque to be applied to the motor 8 in order to return the handle 13 to the rest position.

Therefore, the distributor electronics can control the position of the compensating lever 13, automatically and quickly, precisely because the lever is attached to the drive shaft, thus allowing the operator to change the working tension as desired during processing, for example to gradually change the tension/tightness during the production cycle of the final product (for example, gradual compression on medical socks, etc.). Any change in tension involves a change in the torque of the motor acting on the lever 13, which will always take the rest position (for example "3 o'clock") or return to it in order to keep constant the "current" tension of the yarn or the tension that the yarn assumes during a particular stage of feeding, which is required for that particular stage of production.

In other words, the distributor system is equipped with a control unit (device 1 or distributor 2), including for example a microprocessor, which controls the operation of the motor that directly moves the lever 13. However, this lever, together with the drive shaft to which it is connected, can initially move freely around the axis M (causing the motor to rotate) when the take-up speed by the textile machine or when the feeding conditions vary, which consequently changes the tension of the yarn passing through the annular body 16, which holds lever 13.

Any change in the position of the handle 13 (relative to a predefined reference or rest position, eg "3 o'clock") is detected by the control unit of the distributor system, via the signals coming from the element 19 for detecting the position. This data is fed to said electronic control unit (60, 70) for the distributor system to close the control loop.

In particular, the control unit 70 of the device 1 can detect how much the handle 13 (angularly) has moved from the reference position, and based on this value the control electronics 60 of the distributor 2 can monitor, change and control the power supply of the belt motor 4, so that it changes the rotation speed to compensate for the angular movement of the handle 13 in relation to the reference position. In this way, the distributor 2 uses the information about the position of the lever 13 to anticipate the change (acceleration/deceleration of the belt 4), further improving the quality of the tension during delivery. This is consistent with the "active-predictive" mode of operation described above.

Also in this case (as in the case of EP 2262940) the compensating device 1 acts as a "balance" and the electronics of the distributor system will calculate in real time the torque to be applied to the motor 8, acting together with the lever 13, to always keep it in balance in a fully automatic manner. This depends on the "current" yarn tension F (obviously to maintain a pre-defined tension).

Controlling the position of the handle 13, in this way, also has a compensatory effect on the tension during delivery, which leads to the total elimination or drastic reduction of tension peaks and relaxation of the yarn itself. In fact, when the textile machine T suddenly increases the demand for the yarn F, and the dynamics of the motor driving the belt 4 is not sufficient to compensate for such a change, the lever 13 will tend to fall (moving towards the "6 o'clock" position) increasing the amount of yarn F sent to the machine T; this takes place until the belt motor 4 reaches the required rotation speed to eliminate or reduce the peak tension. At that point, the lever will automatically return to its home or rest position.

Conversely, when the textile machine suddenly reduces the demand for yarn, and the dynamics of the motor driving the belt 4 is not sufficient to compensate for such a change, the lever 13 will tend to rise (moving towards the "12 o'clock" position of drawing 8) reducing the amount of yarn F sent to the machine T, until the belt motor 4 reaches the necessary rotation speed to eliminate or reduce the yarn slack. At that point, the lever will automatically return to its home or rest position (Figure 6).

In its first solution, the rest position of the handle 13 lies within the range of movement of the compensating device or the handle 13, which has two limiting positions (ie 6 o'clock and 12 o'clock).

Also, knowing the position of the compensating lever 13, precisely and in real time, the electronics of the distributor 2 can use this information to speed up or slow down the rotation of the belt 4 in order to minimize the time for establishing a new ideal speed in order to obtain and maintain a constant set value of the tension of the yarn F, further limiting the amplitude of peaks of tension and relaxation of the yarn F.

Also, knowing the position of the compensating lever 13 and the value of the tension, measured by the sensor 3, precisely and in real time during the transition phases (changes in the download speed), the distributor system can change the drive of the motor 8 acting together with the lever 13 to further reduce the change in tension during delivery by the distributor 2; for example:

i) during the sudden acceleration phase, the lever 13 tends to fall (movement towards the "6 o'clock" compensation position, from drawing 7) and the measured yarn tension tends to increase; in this case, the electronics of the distributor system may decide to:

1) interrupt the closure of the loop that controls the position of the lever 13 or reduce its effect, so that the yarn can lower the lever 13 until the tension of the yarn is within the predefined limits, thus using this interval to move from the 3 o'clock position to the 6 o'clock position, as a stock of yarn F to be fed; 2) automatically set the set operating point of the lever 13 in a lower position, in order to provide a greater amount of yarn F to the textile machine T, until the critical condition is overcome.

(ii) during the sudden deceleration phase, the lever 13 tends to rise (movement towards the "12 o'clock" compensation position, from drawing 8) and the measured yarn tension tends to fall; in this case, the distributor system may decide to:

1) interrupt the closure of the loop that controls the position or reduce its effect, so that the lever 13 can recover the yarn F, until the tension of the yarn is within the predefined limits, thus using the interval to move from the 3 o'clock position to the 12 o'clock position, acting in order to recover the excessive amount of supplied yarn;

2) automatically set the set working point or rest position of the handle 13 in a higher position, in order to provide a smaller amount of yarn F to the textile machine T, until the critical condition is overcome.

The set point or reference value for the control loop of the position of the compensating lever 13, here assumed, for example, to be the "3 o'clock" position (Figure 6), may instead be variable and suitably dynamically controlled by the distributor electronics to allow (for example) an eventual subsequent lead-in phase; for example, during a phase where the yarn is slowed down and then stopped by the textile machine, the set point can automatically move to the 12 o'clock position, so that a larger supply of yarn F is provided for future acceleration or restart, thus further reducing the next peak.

In the following solution of the invention (already included in the drawings), there is also a drum or cylinder 26, on which the yarn is deposited during the recovery phase, and which is connected to the compensating lever 13, which increases the amount of stored yarn F, because the amplitude of the angular sector of rotation has increased and in this case is no longer limited to the position between 6 o'clock and 12 o'clock, but can freely rotate around the axis of rotation M.

The drum on which the yarn is placed can be connected to the handle 13 or it can rotate freely on bearings that make its rotation independent. The diameter of the drum determines the maximum amount of yarn F that can be recovered from the device 1 / distributor system 2. Therefore, this drum has different dimensions, depending on the desired amount of yarn F to be recovered on it. The drum can be cylindrical, semi-cylindrical or can have a variable cross-sectional shape.

The compensation device can work without mechanical stops, which prevent it from rotating outside the sector between the 6 o'clock and 12 o'clock positions, which allows the lever 13 to rotate without restriction around the axis, during the recovery phase. In this case, the arm 13 is free to deposit a much larger amount of yarn, stored on the drum 26 during the recovery phase, which is then fed back to the textile machine at the next restart.

This results in a double "reservoir" of yarn, i.e. drum 26, in addition to belt 4. Thanks to the subject invention, one "system" can work even with very different yarn tensions, without the need for any action by the operator. This system is able to compensate for sudden changes in feed, without causing tension peaks or yarn relaxation, as well as to recover, to a small extent, larger amounts of yarn F compared to the previously described current solutions.

Various solutions of the invention are described. Of course, other solutions are possible. For example, the annular ceramic body of the handle 13 can be replaced with a body made of any other material, which has sliding characteristics adequate for this application. In addition, the text describes the use of brushed DC motors, but it is clear that any type of electric motor or actuator (brushless, stepper, etc.) can be used, as well as pneumatic motors.

The use of encoders with Hall sensors is described, for detecting the rotation of the drive shaft, but any encoder available on the market can be used, or the Hall sensor can be installed in the motor; in this case, there is no need for the drive shaft to stick out on both sides.

In addition, the handle 13 is rigid, although it may have minimal flexibility, so that it further dampens the compensating effect, where this flexibility is due to the material or cross-section with which the handle is made. Moreover, this compensating lever is described as rotary, but can be replaced by a lever that follows linear motion, using a linear actuator or motor that moves longitudinally through positions equivalent to the 6, 3, and 12 o'clock positions.

Finally, the existence of a control unit for the device 1 is described, which works together with the control electronics of the distributor 2. Obviously, this control unit can be that of the distributor 2 (that is, it can be part of its control electronics) and can work automatically when the body 11 of the device 1 is connected to the distributor 2, automatically recognizing the presence of the device 1 (the presence of the body 11 is detected by the corresponding connectors, not shown, through which the control unit works together with the motor of the device 1 and the encoder or position sensor for the drive shaft, connected to the lever 13). This solution is shown in Figure 10C.

The invention relates to the distribution of textile yarn, but also to metal wires. Also, these variants are considered to be included within the scope of the invention, as defined by the appended claims.

Claims (14)

PATENT REQUESTS 1. A method for feeding yarn or threads, including metal wires, to a textile machine (T) at constant tension, or to a machine for processing metal wire, wherein said yarn feeding is discontinuous, i.e. in sequential stages in which the yarn (F) is moved at at least a first or at least a second condition of feeding or taking up by the machine, which are different from each other, where said conditions follow each other in time, said feeding is carried out by means of a yarn distributor (2) which has tension/tension detection devices (3), a yarn accumulation element (4) driven by its own electric motor and a control element (60) connected to such a tension detection device (3), wherein a compensating device (1) is provided connected to said distributor (2) which acts together with the yarn (F) coming from said accumulation element (4) before acting together with said tension detection device (3), wherein said compensating device (1) can compensate for changes in supply conditions or yarn take-up (F) at the transition between each first and each second feed or take-up condition, following the first, thereby enabling the control element (60) of the distributor to act on the accumulation element (4) to change its action on the yarn and maintain the tension value, detected by the detection device (3), constant over time and equal to the set value, said constant tension also being maintained during the feed condition change phase, thanks to the interaction between said yarn and said compensating device (1), where the compensating device (1) contains a movable compensating element (13) which carries the body (16) and can act together with the yarn (F) at one free end, wherein said movable compensating element can be moved from a predefined rest position in the direction of feeding the yarn (F), when the yarn passes from a state of less take-up to a state of greater take-up, but moves in the opposite direction when the yarn (F) passes from a state of greater take-up to a state of less take-up, whereby said compensating element (13) returns to rest position at the end of such takeover change, indicated by the fact that control of the movement of said compensating element (13) is provided by means of its own corresponding electric motor (8) directly and rigidly connected to said compensating element (13) and which can directly control the movement of said compensating element (13), wherein said compensating element (13) is a rigid lever, controlled in accordance with the set or detected yarn tension (F) and the measured position during each stages of feeding into the textile machine. 2. The method according to claim 1, characterized in that the compensating element (13) and its electric motor (8), which controls its movement directly and strictly, work in a passive dynamic mode, wherein said compensating element (13) can move freely, together with the motor, under the action of the yarn force (F), but returns to the rest position after such movement by the electric motor (8), where said motor (8) generates a torque that can maintain said compensating yarn element (F) in the rest position, when feeding the yarn into the textile machine. 3. The method according to claim 1, characterized in that the compensating element (13) and the corresponding electric motor (8), which controls its movement, work in active-predictive mode, whereby the motor (8) moves the compensating element (13) from the rest position to the compensation position, responding to the change in yarn tension (F), as soon as such a change is detected. 4. The method according to claim 1, characterized in that it provides continuous control of the electric motor (8) of the compensating device by means of a control unit (60, 70) connected directly or indirectly to the device (3) for detecting tension. 5. The method according to claim 1, characterized in that it is alternatively provided that the said compensating element (13) rotates around a fixed axis (M) of the drive shaft, which comes out of the electric motor to which the said compensating element is rigidly connected, or moves along the compensating device (1). 6. The method according to claim 1, characterized in that the accumulation of yarn (F) on the compensating device (1), in addition to the accumulation of yarn on the element (4) for accumulation, of the distributor (2) is further provided for. 7. The method according to claims 1 and 5, characterized in that the movement of the compensation element (13) is alternatively angularly limited or unlimited. 8. A system for feeding yarn, including metal wires or threads, to a textile machine (T) at constant tension, or to a metal wire processing machine, wherein said yarn feeding is discontinuous or in sequential stages in which the yarn (F) moves at least the first or at least second conditions of feeding or taking up by the machine, which are different from each other, where said conditions follow each other in time, wherein said feeding system operates in accordance with the process of the claim 1, and comprises a yarn distributor (2) having tension/tension detection devices (3), a yarn accumulation element (4) driven by its own electric motor and a control element (60) connected to such tension detection device (3) and accumulation element (4) and capable of acting on said accumulation element (4) based on the tension obtained from such tension detection device (3), wherein a compensating device (1) is provided connected to by said distributor (2) acting together with by the yarn (F) coming from said accumulation element (4), before acting together with said tension detection device (3), wherein said compensating device can compensate for changes in the feed or take-up condition of the yarn (F) at the transition between each first and every other feed or take-up condition, following the first, thereby enabling the distributor control element (60) to act on the accumulation element (4) to change its action on the yarn and maintain the tension value, detected with a detection device (3), constant over time and equal to a set value, wherein said constant tension is also maintained even during the stage of change of feeding conditions, thanks to the interaction between said yarn and said compensating device (1), where the compensating device (1) contains a movable compensating element (13) which can be moved from a predefined rest position in the direction of yarn feeding (F), when the yarn passes from a state of lower take-up to a state of higher take-up, but moves in the opposite direction when yarn (F) transitions from a higher uptake state to a state less take-up, wherein said compensating element (13) returns to the rest position at the end of such take-up change, characterized in that the compensating element (13) is a rigid lever carrying a terminal body (16) that can act together with the yarn (F), wherein said rigid lever (13) is directly and rigidly connected to its own electric motor (8) which directly controls its movement in accordance with the set or detected tension of the yarn (F), wherein the mentioned a rigid arm placed between said yarn accumulation element (4) and said tension detection device (3), but separated from it. 9. System according to claim 8, characterized in that alternatively the resting position of the compensating element (13) lies within the range of movement of such a compensating element, which has two limit positions or is defined within the circular path of such an element around the axis (M), wherein said path is not angularly limited. 10. System according to claim 8, characterized in that a position detection device (19) is provided to determine the position of the rigid lever (13), wherein said position detection device (19) is connected to the drive shaft of said electric motor, which also carries said rigid lever. 11. System according to claim 10, characterized in that the provided control unit (60, 70) for the electric motor (8) of the compensating device (1) is connected to the device (19) for detecting the position and which can detect the movement of the compensating element (13) from the predefined rest position by means of the said device (19) for detecting the position and can return the said compensating element (13) to the predefined rest position through the control of the electric motor for which it is compensated the element (13) is firmly and directly connected, wherein said control unit (60, 70) is directly or indirectly connected to the yarn tension detection device (3), and controls the electric motor based on the detected yarn tension/tension (F) when said yarn (F) is fed to the machine. 12. System according to claim 11, characterized in that said control unit (60, 70) is alternatively connected to the compensation device (1) and connected to the control device of the distributor (2) or said control unit is part of the control device of the distributor (2). 13. System according to claim 8, characterized in that said compensating device (1) is a component independent of the distributor (2), in that said compensating device (1) is detachably attached to the distributor (2) and located at one end (2A) or on one side of said distributor, in that said compensating device (1) is fully automatic, in relation to said distributor (2), but is closely connected to said distributor when connected to it. 14. System according to claim 8, characterized in that said compensating device (1) has an element (26) which rotates about its axis and can accept the yarn (F) which is wound under one of the mentioned conditions of feeding or taking up by the machine.