Patent Description:
As is known, industrial-type winding machines comprise a plurality of winding units that are independent of each other and controlled by a programmable control unit.

The winding unit is used for winding a yarn on a support, generally cone-shaped, to create a spindle that will be used in weaving, knitting, or other subsequent processing. The yarn is wound on the support with a predetermined type of winding to optimize the subsequent unwinding of the yarn from the spindle during the weaving stage.

In this discussion the term "thread" or "monofilament" or "continuous thread" means a single filament or continuous strand (for example in the case of silk, artificial, or synthetic fibers), while the term "yarn" means the set of fibrils of variable length that are parallelized and joined by twisting. In the following, either term will be used indistinctly, it being understood that the applications of the present invention are not limited to one or the other type.

The yarn is wound on the spindle preferably with a cylinder in contact with said spindle and rotating about an axis substantially parallel to that of the spindle. The cylinder is provided with a predetermined geometry of seats that are engaged by the yarn and guide it during its winding onto the spindle.

It is self-evident that high winding speeds of the yarn onto the spindle correspond to high unwinding speeds of the bobbins that supply the yarn.

One of the main results of increasing the unwinding speed of the bobbin, is the increase in the tension due to unwinding, which in some cases may cause the yarn to break, and which in any case is detrimental to the yarn because the defectiveness may increase the specific pressures in the contact points of the thread.

The yarn in the vicinity of the bobbin forms a so-called balloon: as it unwinds from the bobbin, it becomes wider with respect to the shape of the yarn wound on the bobbin, and this widening extends for a certain height above the bobbin, up to the cylindrical connection point placed above the tube. The more the unwinding speed increases, the more the diameter of the balloon increases until it collapses and slides onto the tube, thus losing its characteristic shape. Essentially, as the speed increases, the centrifugal force is not sufficient to overcome the other forces involved (Coriolis force in primis but also aerodynamic resistance force), and the balloon closes up on the tube.

In addition, as the bobbin is emptied, there is a further increase in tension due to the lowering of the pickup point of the thread from the bobbin and a consequent increase in height of the balloon and the possible collapse thereof.

The correlation between the balloon diameter and the tension due to unwinding is well known; in particular, it is known that as the unwinding speed of the bobbin increases, the balloon diameter increases and consequently so does the unwinding tension. Moreover, in the event that the balloon collapses, the tension is further raised by the friction generated between the thread and tube. Such friction, inter alia, may deteriorate the yarn.

The prior art has tried to solve this problem by attempting to confine the diameter of the balloon, passing the yarn inside a containment element that is part of a system called a balloon breaker, substantially cylindrical in shape, coaxial with respect to the bobbin, and positioned near the upper end of the bobbin.

As the bobbin is emptied, the pickup point of the yarn from the bobbin is lowered, increasing the height of the balloon, and thus increasing its maximum diameter until it collapses. This increase in height causes the containment effect to be lost, significantly reducing the effectiveness of such systems.

For this reason, the known types of balloon breakers provide additional functions, such as a downward shift of the containment element as the amount of yarn remaining on the bobbin decreases.

This solution is particularly favored because it allows an optimal distance to be maintained between the yarn still wrapped on the bobbin and the containment element, thus allowing an optimal confinement of the balloon inside the containment element.

However, the system is technically complex and expensive since each winding machine may comprise dozens of winding units and thus dozens of such devices.

In effect, the movement is carried out through a motor connected to a screw element parallel to the direction of movement of the containment element, using for the movement a so-called screw-nut coupling.

The device also comprises sensors, for example optical sensors, which are adapted to detect the height of the portion of the bobbin covered by yarn and transmit this information to a programmable control unit, which consequently commands the motor to lower the containment element.

Therefore, as mentioned above, the solutions proposed by the prior art, although widely used and functional, are not free from drawbacks.

First, the system is very complex because it requires continuous monitoring of the winding state of the yarn on the bobbin in order to continuously move the containment element.

Further, as stated above, it is an expensive system because it envisages the use of a motor, means to transform a rotational motion into a translational motion of the containment element, and sensors to evaluate the amount of yarn wound on the bobbin.

Thus, it is obvious that the cost of incorporating these devices into all the winding units has a major impact on the final cost of the winder.

These systems further provide for the system to rise whenever there is a breakage to allow the thread to be picked up freely from the bobbin with the appropriate nozzles or even to provide additional means for retaining the thread.

Moreover, the reduction in tension that is achieved may, with some yarns, worsen the hairiness of the yarn due to the friction that is generated. <CIT> discloses an apparatus for preventing scatter of fly in a winder having a plurality of winding units, the apparatus including a balloon breaker. A first cover member for covering the yarn feeding bobbin unwound at a winding unit and a second cover member for covering a tenser portion are provided with each winding unit.

<CIT> discloses a cover in a winder for controlling the ballooning of yarns.

There is therefore a need to at least partially resolve the disadvantages and limitations mentioned with reference to the prior art.

Thus, there is a need to provide a device for controlling the tension of the balloon that allows the unwinding tension to be better managed and the production speed to be increased without adding hairiness to the thread. Such a device should have a simpler structure than the devices of the prior art and thus be easily and inexpensively implemented in a winding unit.

Moreover, always with a view to simplifying the structure of the device, there is a need for a system that does not require the use of additional sensors to establish the winding state of the yarn on the bobbin.

Also, there is a need for a device for controlling the balloon that is more effective than the devices of the prior art.

These requirements are at least partially met by a device for controlling a balloon according to claim <NUM>, a winding unit comprising said device according to claim <NUM>, and a method for controlling the balloon according to claim <NUM>.

Further features and advantages of the present invention will become more apparent from the following detailed description of preferred, non-limiting embodiments thereof, wherein:.

Elements or parts of elements common to the embodiments described hereinafter will be indicated with the same numerical references.

In <FIG> the general numerical reference <NUM> is used to indicate a device for controlling a balloon during the unwinding of a yarn <NUM> from a bobbin <NUM> in a winding unit <NUM>.

As shown in the figures, the first containment element <NUM> comprises a first containment component <NUM> and a second containment component <NUM>. Further, the support <NUM> comprises a first arm <NUM> and a second arm <NUM> on which the first containment component <NUM> and the second containment component <NUM> are respectively positioned.

The device <NUM> comprises drive means <NUM> adapted to move the arms <NUM>, <NUM>, and consequently the containment components <NUM>, <NUM>, between two positions: a first position wherein the containment components <NUM>, <NUM> are spaced apart from each other, and a second position wherein the containment components <NUM>, <NUM> are closer together with respect to the first position.

According to a possible embodiment, in the second position the containment components <NUM>, <NUM> may be in contact with each other.

In other words, in the first position, the containment components <NUM>, <NUM> may be spaced apart so as not to interact substantially with the balloon that develops during the unwinding of the yarn <NUM> from the bobbin <NUM>.

Whereas, in the second position, the containment components <NUM>, <NUM> may be closer together, and possibly in contact with each other, so as to interact substantially with the balloon that develops during the unwinding of the yarn <NUM> from the bobbin <NUM>.

According to a possible embodiment, one or more intermediate positions may be provided between the first position and the second position of the containment components <NUM>, <NUM> so as to allow for a containment of the balloon depending on the size of said balloon.

According to a possible embodiment, in the second position, the through opening <NUM> may be substantially cylindrical with an outward flaring <NUM> at the input portion of the yarn <NUM>.

In effect, as shown for example in <FIG> or <FIG> the containment components <NUM>, <NUM> may have a widening, and therefore an increase in the diameter of the through opening <NUM>, at the input portion of the yarn <NUM>.

According to a possible embodiment, the through opening <NUM> may have a narrowing <NUM> at a position opposite the input of the yarn of the through opening <NUM>.

According to a possible embodiment, which may be seen for example in <FIG>, the first arm <NUM> and the second arm <NUM> may rotate in opposite directions about respective rotation axes y, z spaced apart from each other and substantially parallel to said axis x.

The first arm <NUM> and the second arm <NUM> may be provided with cogwheels <NUM>, <NUM>, integral with their respective arms, which mesh with each other and are adapted to rotate about their respective axes y, z, so that the rotation of one arm causes the rotation of the other arm and are therefore synchronous.

One such embodiment is shown, for example, in <FIG>, wherein the cogwheels <NUM>, <NUM> are shown, which may also be incomplete and provided only at one portion of the circumference of the cogwheel.

According to a possible alternative embodiment, the drive means may comprise alternative systems to the cogwheels <NUM>, <NUM> such as an articulated, quadrilateral kinematic motion or a crank mechanism.

According to a possible embodiment, the drive means <NUM> may comprise a linear actuator <NUM> connected to one of the arms <NUM> at a lever <NUM> arranged on the arm <NUM>, whereby a linear movement of one operating end of the linear actuator <NUM> causes a rotation of the arm <NUM>, and consequently of the other arm <NUM>.

The linear actuator may, for example, be a pneumatic actuator, or an electric actuator, in a way known per se to the person skilled in the art.

According to alternative embodiments, the arms <NUM>, <NUM> may be driven in different technical ways, such as through the use of rotary actuators or the like. Also in this case, the actuators used may, for example, be pneumatic or electric.

More specifically, it is also possible to envisage two actuators being provided, one for each arm. In this case, the arms may also be without the coupling with cogwheels.

According to an alternative embodiment, the drive means <NUM> may be adapted to move the containment components <NUM>, <NUM> in a straight direction. For example, a linear actuator shared by both the containment components <NUM>, <NUM> or a linear actuator for each linear element may be provided.

Moreover, the drive means may be suitable for achieving asynchronous movement of the containment components <NUM>, <NUM>.

In a further alternative embodiment, the linear actuator may, for example, be directly keyed to one of the containment components and, by means of a mechanical transmission, may also move the other containment component.

The device <NUM> comprises a second static containment element <NUM> arranged downstream from the first containment element <NUM>, comprising a second through opening <NUM> arranged with a base portion <NUM> in use facing toward the first containment element <NUM>, having a substantially rectangular cross section with respect to the longitudinal axis x.

Advantageously, the second containment element <NUM> may be arranged on the same support <NUM> as the first containment element <NUM>.

According to a possible embodiment, the base portion <NUM> of the second through opening <NUM> may have a substantially square cross section. More specifically, it may have a substantially square cross section with a side dimension of between <NUM> and <NUM>, preferably between <NUM> and <NUM>, and even more preferably around <NUM>. Further, the height of the base portion <NUM> of the second through opening <NUM>, according to a longitudinal direction perpendicular to the cross section of the second through opening <NUM>, may be between <NUM> and <NUM>, and preferably between <NUM> and <NUM>.

According to a possible embodiment, the substantially rectangular or square cross section may comprise inward protrusions located at the midpoint of each side making up the rectangular or square cross section.

The second through opening <NUM> may comprise a central portion <NUM> having a substantially truncated pyramid shape with a larger base at the base portion <NUM> opposite the input section of the yarn in the second containment element <NUM>.

According to a possible embodiment, the truncated pyramid-shaped central portion <NUM> comprises a smaller base having a substantially circular shape opposite the larger base. The second through opening <NUM> may further comprise a substantially cylindrical end portion <NUM>.

In other words, according to a possible embodiment, the yarn <NUM>, during an unwinding stage of a bobbin, may pass within the first containment element <NUM> and subsequently, within the second containment element, in particular within the base portion <NUM>, the central portion <NUM>, and the end portion <NUM>.

As shown in <FIG>, the sides of the cross section of the second containment element <NUM> may, for example, be joined together so that there are no internal edges.

In effect, precisely because of the rectangular or square cross section, the continuity of the balloon is interrupted during its formation (<FIG>). More specifically, the continuous rubbing and bumping of the yarn on the sides of the containment element delays the formation of the balloon and thus the increase in the longitudinal tension component of the yarn.

Once the amount of yarn in the bobbin decreases, the balloon tends to form, in a lower position than before.

In effect, it was seen that in the first part of the unwinding of the bobbin (<FIG>), the containment of the balloon is less effective than the continuous breakage through the second containment element <NUM>. In this way it is possible to contain the tensions because the height of the balloon is contained.

Once the bobbin begins to empty, for example, about halfway through the bobbin, the second containment element <NUM> loses effectiveness as the balloon height, and consequently the yarn tension, increases.

The height causes the thread to slide on the tip of the tube, thus losing contact with the inner surfaces of the second containment element <NUM> (<FIG>).

At this point, the first containment element <NUM> closes in the second position.

The method for controlling a balloon through a device <NUM> essentially comprises:.

According to an embodiment, the operating parameter used may be a percentage of the yarn unwound from the bobbin.

According to a possible alternative embodiment, the operating parameter may, for example, be the yarn tension, measured downstream of the device <NUM>.

Thus, actuation of the containment element <NUM> from the first position to the second position, or to an intermediate position, if present, may occur when a specified value of the yarn tension measured downstream of the device is exceeded.

Further, to prevent tension spikes from compromising an effective actuation of the first containment element, the actuation of the containment element from the first position to the second position, or to an intermediate position, if present, may be performed when a specified tension value is exceeded a predetermined number of times, or for a predetermined length of time.

In this way, it is possible to prevent a temporary disturbance in the system from compromising the winding.

For example, it is possible to use the thread tension adjustment system that is already installed on the winders. In effect, the thread tensioning system normally works between a minimum and a maximum value which correspond respectively to a maximum and a minimum winding tension, and it is possible to make use of said system to adjust the winding speed, as well as the actuation of the first containment element.

Specifically, the thread tension adjustment system may be used so that the first containment element is actuated when the thread tensioner operates near the minimum value (corresponding to a high winding tension), or when a specified value is exceeded a predetermined number of times, or for a predetermined length of time.

As for the adjustment of the distance between the device <NUM> and the bobbin, this depends on the unwinding parameters as will be obvious to the person skilled in art. More specifically, the distance between the device and the tube of the bobbin may be adjusted according to, for example, the behavior of the balloon at certain unwinding speeds, and the yarn count.

For example, the distance between the second containment element and the tube of the bobbin may be about <NUM>-<NUM>, whereas the distance between the first containment element and the second containment element may be about <NUM>-<NUM>.

According to one possible embodiment, the distance between the end of the tube of the bobbin and the narrowing <NUM> of the first containment element may be between <NUM> and <NUM>.

According to one possible embodiment, the through opening <NUM> may have a diameter of about <NUM>-<NUM>. The narrowing <NUM> may be approximately <NUM>-<NUM> in diameter.

In the attached figures, only a portion of the winding unit is shown, since the other components are known per se to the person skilled in the art.

The advantages of the method according to the present invention are therefore now also apparent.

First, a device and method for controlling a balloon have been provided that allow for more efficient control than devices of the prior art.

In particular, unlike the devices of the prior art, the control of the balloon occurs indirectly, through the measurement of the tension of the yarn during the step of unwinding from the bobbin.

In other words, no dedicated optical sensors or the like are used to determine the degree of filling of the bobbin or the balloon status.

Advantageously, the first containment element <NUM> and the second containment element <NUM> close just above where the yarn detaches from the winding of the coils. Doing so generates a controlled tension sufficient to avoid rubbing against the tube, but not so high as to unwind several coils at once or, worse, so as to break the yarn.

Thus, the main advantages that may be achieved are a stabilization and reduction of the unwinding tension, the fluctuations of which may stress the yarn during said unwinding. In this way it is possible to increase the unwinding speed in the final step, even by <NUM>-<NUM>%.

The result is an increase in productivity, since traditional winding systems, conversely, impose a decrease in winding speed.

Moreover, the effect whereby several coils come off the bobbin at the same time is consistently reduced, and the number of yarn breakages is reduced.

Claim 1:
Device (<NUM>) for controlling a balloon during the unwinding of a yarn (<NUM>) from a bobbin (<NUM>) in a winding unit (<NUM>) comprising:
- a first containment element (<NUM>) substantially tubular, having a longitudinal axis (x) and a through opening (<NUM>) adapted to the passage of the yarn (<NUM>) coming out of said bobbin (<NUM>);
- a support (<NUM>) adapted to support said first containment element (<NUM>), and adapted to be fixed to a structure of a winding unit (<NUM>);
wherein said first containment element (<NUM>) comprises a first containment component (<NUM>) and a second containment component (<NUM>);
wherein said support (<NUM>) comprises a first arm (<NUM>) and a second arm (<NUM>) on which said first containment component (<NUM>) and said second containment component (<NUM>) are respectively positioned;
wherein said device (<NUM>) comprises drive means (<NUM>) adapted to move said arms (<NUM>, <NUM>) and consequently said containment components (<NUM>, <NUM>), between two positions: a first position in which said containment components (<NUM>, <NUM>) are spaced apart, and a second position in which said containment components (<NUM>, <NUM>) are closer together with respect to the first position;
characterized in that said device (<NUM>) further comprises a second static containment element (<NUM>), arranged downstream of said first containment element (<NUM>), said second containment element (<NUM>) being arranged with a second through opening (<NUM>) comprising a base portion (<NUM>) facing, in use, said first containment element (<NUM>), having a substantially rectangular cross-section with respect to said longitudinal axis (x).