EP1550751B1 - Method of controlling the feeding tension of at least one weft yarn, weft yarn feeding device and loom with such a weft yarn feeding device - Google Patents

Description

The invention relates to a method for controlling the supply voltage and to a device for feeding at least one weft thread for a sickle loom. The invention also relates to a loom equipped with such a feeding device.

In the field of looms used for the manufacture of relatively narrow articles, such as ribbons and / or labels, it is known to use a drive member of a weft yarn which is animated by a movement oscillations in pivoting and which is most often referred to as sickle. The sickle must be fed with weft yarn from a spool. Given the oscillation movement or back and forth of the sickle, the tension of the weft thread between the spool and the sickle must be controlled and it is known to use a mechanical device with capstan, called "Donor", possibly associated with a mechanical system of voltage compensation, called "compensator". To obtain adequate tension of the weft yarn upstream of the sickle, the speed of rotation of the donor must be synchronized with that of the sickle, which implies the use of complex mechanical devices, particularly of the gearbox and / or spring type. compensation. The known devices are therefore relatively expensive and their adjustment can be particularly long and tedious.

It is known, for example from EP-A-0 851 833 or EP-A-0 619 261 to control a frame donor brake according to the downstream weft thread tension. It is also known to EP-A-0 467 059 to enslave the position of a lever forming a voltage regulator. These devices are not efficient enough to be associated with a sickle loom. A method of controlling the supply voltage of at least one weft yarn and a feeder according to the preamble of claim 1 and 5 respectively are known from the document US-A-4,298,033 .

It is also known to FR-A-2 352 906 to equip a lance loom with an electrically actuated weft-guiding cylinder according to the position of a compensating arm. Such a mechanism is not responsive enough to be associated with a sickle loom.

It is these drawbacks that the invention intends to remedy more particularly by proposing a new method for controlling the supply voltage of a weft yarn in which it is not necessary to mechanically synchronize the weft donor and the sickle, while the weft yarn is delivered with a tension adapted to its use.

In this spirit, the invention relates to a method for controlling the supply voltage of at least one weft yarn in a loom comprising at least one sickle from a yarn supply, in which method less wire is subjected to the action of a drum frame donor and a device for compensation of its accelerations / decelerations, this device comprising a movable member defining the trajectory of the weft yarn. This method is characterized in that it comprises a step of controlling the operation of an electric drive actuator of at least one drum of the frame donor according to a signal representative of the operation of a second electric actuator which itself drives the aforementioned movable member.

Thanks to the invention, the weft donor can, by the angular position of its drum, not only provide the right amount of yarn required for weaving but also smooth some of the violent accelerations / decelerations of the weft, which allows limit the necessary compensation accordingly. Moreover, the compensation device or "compensator" of the invention not only smoothes a part of the violent acceleration / deceleration of the frame, but also to fix, to a certain extent, the tension of the weft thread independently of its angular position. It also makes it possible to adjust the speed of the donor at each instant according to the frame requirement, by authorizing variable unwinding speeds.

• Le tambour entraîne le fil de trame par rotation, le fil étant enroulé sur le tambour et se déroulant, à partir de celui-ci, de façon tangentielle.
• On utilise comme second actionneur un servomoteur électrique et on commande ce servomoteur à couple sensiblement constant. Ceci permet d'obtenir une tension sensiblement constante du fil de trame, entre le compensateur et la faucille.
• La commande de la position angulaire du tambour est effectuée de telle sorte que la tension du fil de trame, en aval du donneur et du dispositif de compensation, est sensiblement égale à une valeur pré-déterminée.

According to advantageous aspects, a method for controlling the supply voltage of a weft thread may incorporate one or more of the following features:

• The drum drives the weft yarn by rotation, the yarn being wound on the drum and running from it tangentially.
• As the second actuator, an electric servomotor is used and this servomotor is controlled with a substantially constant torque. This makes it possible to obtain a substantially constant tension of the weft thread between the compensator and the sickle.
• The control of the angular position of the drum is carried out so that the tension of the weft thread, downstream of the donor and the compensation device, is substantially equal to a predetermined value.

The invention also relates to a weft yarn feeding device of a loom comprising at least one sickle which makes it possible to implement a method as previously described and, more specifically, a device comprising a supply of yarns of frame, at least one weft drive drum and at least one device for compensation of its accelerations / decelerations of this thread which comprises a movable member defining the trajectory of the weft yarn. This device is characterized in that the drum is rotated by a first electric actuator, in that the movable member is driven by a second electric actuator and in that means are provided for measuring the position of the aforementioned movable member, while means are also provided for controlling the first electric actuator according to the result of the measurement made by the measuring means.

Thanks to the device of the invention, the position of the drive drum, which in practice belongs to the weft donor, can be controlled in a way that allows it to constantly adapt to the movements of the back and forth of the sickle and compensate for some of the resulting accelerations and violent decelerations of the weft yarn.

• Les moyens de mesure sont aptes à détecter la position d'une partie mobile du second actionneur et à générer un signal électrique de commande de l'actionneur d'entraînement du tambour. Le second actionneur peut être un servomoteur rotatif ou un servomoteur linéaire. De façon avantageuse, le second actionneur est alimenté de façon à générer un couple sensiblement constant.
• L'actionneur électrique peut entraîner plusieurs tambours, alors que les moyens de mesure sont aptes à déterminer la position commune de plusieurs organes mobiles qui définissent la trajectoire des fils de trame entraînés par ces tambours. Dans ce cas, un second actionneur peut être apte à déplacer simultanément les organes mobiles, alors que les moyens précités sont aptes à mesurer la position de se second actionneur et à générer un signal électrique de commande de l'actionneur d'entraînement des tambours.

According to advantageous but not mandatory aspects, a weft feeder can incorporate one or more of the following features:

• The measuring means are able to detect the position of a moving part of the second actuator and to generate an electrical control signal of the drive actuator of the drum. The second actuator may be a rotary servomotor or a linear servomotor. Advantageously, the second actuator is powered to generate a substantially constant torque.
• The electric actuator can drive several drums, while the measuring means are able to determine the common position of several moving members that define the trajectory of the weft son driven by these drums. In this case, a second actuator may be able to simultaneously move the movable members, while the aforementioned means are able to measure the position of the second actuator and to generate an electrical control signal of the drive actuator drums.

The invention finally relates to a sickle loom equipped with a feed device such as described above. Such a craft is easier to install and can operate at a higher speed than those of the state of the art.

• la figure 1 est une représentation schématique de principe d'un dispositif conforme à l'invention intégré dans un métier à tisser conforme à l'invention ;
• la figure 2 est une représentation schématique de principe en perspective d'une partie du dispositif de la figure 1 et
• la figure 3 est une représentation schématique de principe en perspective d'une partie d'un dispositif conforme à un second mode de réalisation de l'invention.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of two embodiments of a feeding device, a loom and a control method in accordance with its principle, given solely by way of example and with reference to the appended drawings in which:

• the figure 1 is a schematic representation of a device according to the invention integrated in a loom according to the invention;
• the figure 2 is a schematic representation of principle in perspective of a part of the device of the figure 1 and
• the figure 3 is a schematic representation of a perspective view of a part of a device according to a second embodiment of the invention.

The device represented in figures 1 and 2 is intended to allow weft feed of a sickle 1 animated with an oscillating pivoting movement, represented by the arrow F ₂ , around a fixed point 2.

Given the oscillating movement F ₂ of the sickle 1, the weft thread 3 is moved relative to the warp threads 4 of the loom M, which makes it possible to weave a ribbon R which moves in the direction of the arrow F ₃ .

The sickle 1 is supplied with weft thread 3 from a spool 10. Starting from the spool 10, the thread 3 passes through a fixed guide eyelet 11 and a thread brake 12 known per se which ensures the tension of the thread 3 by applying on it a constant pressure P ₁ , this pressure being adjustable, as represented by the arrow F ₄ .

After passing through the wire brake 12, the wire 3 runs along a return roller 14 and then is wound on a drum 15 belonging to a weft donor 16 whose function is to deliver to the sickle 1 a corresponding quantity of threads 3 to the reciprocating movements of its free end 5. In practice, the wire 3 can be supported on about 180 ° on the drum 15 or make one or more turns around it.

The frame donor 16 also comprises a servomotor 17, for example a brushless motor, controlled by a suitable electronic unit 18.

Downstream of the drum 15, the wire 3 bears on a second roller 19 and then passes through an eyelet 20 mounted at the free end of an arm 21 movable between the two positions shown in phantom at the figure 1 , which allows the eyelet 20 to describe a trajectory globally in a circular arc C ₁ .

The position of the arm 21 is controlled by a second servomotor 22, for example a brushless motor which is powered to generate a substantially constant torque.

From the eyelet 20, the wire 3 passes through a second fixed eyelet 23 and then passes through an eyelet 6 formed at the free end 5 of the sickle 1.

The torque C ₂ exerted by the motor 22 on the arm 21 directly influences the tension T of the weft thread 3 between the eyelets 23 and 6.

The motor 22 is powered such that, taking into account the path of the wire 3 between the elements 19, 20 and 23, the voltage T is substantially constant, the value of this constant being adjustable by the setting of the motor power supply 22.

A sensor 25 is installed near the actuator 22 for detecting the angular position θ of the rotor 22 a.

The sensor 25 is connected to the unit 18 and its electrical output signal S ₁ is supplied to this unit to control the servomotor 17 and thereby the drum 15, so as to deliver a quantity of weft yarn 3 which reduces Permanently the arm 21 in the desired position. As a result, the drum 15 delivers the amount of weft yarn 3 just needed for the movements of the end 5 of the sickle 1.

The assembly formed of the elements 20 to 21 constitutes a compensation device or "compensator" 27 which smooths part of the violent accelerations / decelerations to which the weft thread 3 is subjected because of the movements of the sickle 1.

Thus, the donor 16 provides the right amount of yarn required for weaving and participates in the smoothing of the violent accelerations / decelerations of the weft yarn, since the signal S ₁ makes it possible to adjust the advance of the weft thread as a function of the position of the arm 21. In addition, the compensator 27 makes it possible to give a tension T substantially constant and of desired value to the weft thread in the vicinity of the sickle, this relatively independently of the position of the sickle during its movement F ₂ .

In other words, the invention makes it possible to adjust, at each instant, the speed of the donor 16 as a function of the need for weft thread, so that the quantity of thread supplied by the donor 16 is always in line with the need weft yarn which has, moreover, a tension T substantially constant.

The juxtaposition of several devices according to the invention makes it possible to obtain the same tension for the different weft threads used in the same loom equipped with several sickles.

In this case, and as shown in figure 3 a single servomotor 17 may be used to drive, around the same axis A-A ', several drums 15 ₁ to 15 _n which are in number corresponding to the number of sickles ₁₁ to 1 _n . A single servomotor 22 is, moreover, used to drive, simultaneously and around another axis B-B ', n arms 21 ₁ to 21 _n in the eyelets 20 ₁ to 20 _n which pass the weft son 3 ₁ to 3 _n . The torque C ₂ exerted by the servomotor 22 is adjusted to take into account the number of arms 21 ₁ to 21 _n to be driven.

As before, an electrical signal S ₁ is used by a control unit 18 to drive the motor 17 as a function of the angular position of the motor 22 detected by a sensor 25.

The invention can also be implemented when each sickle is fed with several weft son. In this case, as many donors are used as son and son are selected and presented to the sickle by a conventional frame selector.

Furthermore, a single pair of donor 16 and compensator 27 can be used for a wide range of weft thread voltages since only the adjustment of the torque of the servomotor 22 makes it possible to adjust this voltage.

In practice, whatever the embodiment, the servomotors 17 and 22 are structurally identical.

According to a not shown variant of the invention, the motor 22 can be replaced by a linear motor within the compensator 27.

Claims (12)

1. Process for controlling the supply tension of at least one weft yarn, in a weaving loom comprising at least one sickle (1), from a reserve (10) of yarns, in which process at least one yarn is subjected to the action of a weft feeder incorporating a drum and of a device (27) for compensating its accelerations/decelerations, which comprises a mobile member (20, 21) defining the path of the weft yarn, characterized in that it comprises a step consisting in controlling the functioning of a first electrical actuator (17) for driving at least one drum (15) of the weft feeder (16) as a function of a signal (S₁) representative of the functioning of a second electrical actuator (22) which itself drives said mobile member (20, 21).
2. Process according to the preceding Claim, characterized in that said drum (15) drives the weft yarn (3) by rotation, the yarn being wound on the drum and unwinding therefrom in tangential manner.
3. Process according to one of the preceding Claims, characterized in that an electrical servo-motor (22) is used as second actuator and in that said servo-motor is controlled with substantially constant torque.
4. Process according to one of the preceding Claims, characterized in that control of the angular position of said drum (15) is effected such that the tension (T) of the weft yarn (3), downstream of said feeder (16) and of said compensation device (27), is substantially equal to a pre-determined value.
5. Device for supplying weft yarn in a weaving loom comprising at least one sickle, said device comprising a reserve (10) of weft yarns (3), at least one weft yarn drive drum (16) and at least one device (27) for compensating the accelerations and decelerations of the weft yarn comprising a mobile member (20, 21) defining the path of the weft yarn, said drum (15) being driven in rotation by a first electrical actuator (17), characterized in that said mobile member (20, 21) is displaced by a second electrical actuator (22) and in that means (25) are provided for measuring the position (θ) of said mobile member (20, 21), while means (18) are also provided for controlling said first electrical actuator as a function of the result (S₁) of the measurement effected by said measuring means.
6. Device according to Claim 5, characterized in that said measuring means (25) are adapted to detect the position (θ) of a mobile part (22a) of said second actuator (22) and to generate an electric signal (S₁) for controlling the first actuator (17).
7. Device according to Claim 6, characterized in that said second actuator (22) is a rotating servo-motor.
8. Device according to Claim 6, characterized in that said second actuator is a linear servo-motor.
9. Device according to one of Claims 7 or 8, characterized in that said second actuator (22) is supplied so as to generate a substantially constant torque (C₂).
10. Device according to one of Claims 5 to 9, characterized in that said electrical actuator (17) drives a plurality of drums (15_l-15_n), while said measuring means (25) are adapted to determine the position (θ) of a plurality of mobile members (20_l-20_n, 21_l-21_n) defining the path of the weft yarns (3_l-3_n) driven by said drums.
11. Device according to Claim 10, characterized in that a second actuator (22) is adapted to displace said mobile members (20, 21) simultaneously, and in that said means (25) are adapted to measure the position (θ) of said second actuator and to generate an electric signal (S₁) for controlling the actuator (17) driving the drums.
12. Weaving loom (M) of sickle (1) type equipped with a device (10-27) for supplying weft yarn according to Claims 5 to 11.

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