EP3984933A1

EP3984933A1 - Improved kink prevention device for a winding machine and a related method for removing kinks in the yarn in a winder

Info

Publication number: EP3984933A1
Application number: EP21199510.5A
Authority: EP
Inventors: Stefano Malfante; Ivan BERTOLO; Mauro Moro
Original assignee: Savio Macchine Tessili SpA
Current assignee: Savio Macchine Tessili SpA
Priority date: 2020-10-15
Filing date: 2021-09-28
Publication date: 2022-04-20
Also published as: IT202000024283A1; CN216807609U; CN114368644A

Abstract

A kink prevention device (4) for a winder comprising a presser element (24), movable along a transverse direction of actuation (T-T) from a rearward position to a forward position according to an actuation stroke, the presser element (24) being provided with a rod (28), operatively connected to actuation means (32) and a head (36), associated with the rod (28) and shaped so as to exert a pressure and friction action on a yarn (12), a striker (40), separate from and opposed to the presser element (24) along said transverse direction of actuation (T-T), on the opposite side of a receiving volume (44) of the associated yarn (12), so that the yarn (12) is located between the head (36) and the striker (40). The striker (40) is equipped with an end wall (48) that defines an end stop of the forward position of the presser element (24).

Description

FIELD OF APPLICATION

The present invention relates to an improved kink prevention device for a winding machine and a related method for removing kinks in the yarn in a winding machine.

STATE OF THE ART

During the winding operation, the thread or yarn is in motion and unwinds from the bobbin, generating a balloon at high speed, to be able to then be rewound on a reel, after any possible defects have been eliminated by the yarn clearer. The formation of the balloon has been the subject of studies, from which it follows that the balloon generally has a complex ovoid shape that varies continuously as the unwinding of the yarn progresses.
It should be clarified that 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, one or the other term will be used indiscriminately, it being understood that the applications of the present invention are not limited to either type.
In certain conditions, depending on the speed, the distance of the bobbin from the unwinding point, and the weight of the unwound segment of yarn, the balloon may collapse on the tube, thus generating, through friction between the yarn and the tube, high tensions that lead to deterioration of the yarn and its breakage. To prevent this effect, winding machines are equipped with appropriate devices adapted to interrupt the formation of balloons of this type, which are generally called balloon breakers.
It should then be noted that, upon the cutting of a defect by the yarn clearer, the yarn is suddenly broken into two parts or ends, one toward the reel and the other toward the bobbin. Both of these ends must be controlled in order to be handled properly by the winding head members to form a subsequent splice and to allow the yarn winding on the reel to be restarted.
For this purpose, the reel is immediately braked; however, given its high initial rotational speed, in the short time between cutting and braking, the portion of the cut yarn toward the reel is wound onto the same reel and thus its end may effectively be located on the reel by movable members or suction nozzles.
The interrupted portion on the side of the bobbin, however, is no longer subject to any traction and remains free. The end that is along the yarn path on the members of the winding head is sucked in and held by a fixed, properly positioned suction nozzle, or is held by a yarn tensioner or other member.
However, the section that is detached from the bobbin cone by inertia still unwinds by a small amount, and, due to the lack of tension in the yarn, it may form a kink or loop on the yarn, by winding on itself.
It is known that the greater the twists in the yarn and the less relaxed the yarn is, the more kinks will occur. Since the transit of a kink or loop through the yarn clearer generates an unwanted cut and an overall decrease in the efficiency of the winder, as well as unnecessary and undesired splices, kinks should be prevented, and those that do occur must be stretched out when restarting the winding process. It is common, for particularly fibrous and high-twist yarns, to steam such yarns at high temperature and for a certain time, in order to relax the yarn and prevent the effect of self-winding of the yarn on itself.
The function of a kink prevention device should be threefold:
1. Immediately after the yarn clearer cutting, it is necessary to enter into contact with the yarn to stop its inertia and prevent it from unwinding from the tube; in effect, if it unwinds, the portion of yarn lacks tension and can wrap around itself;
2. During transport of the yarn to the splicer by the bobbin nozzle, a small amount of tension must be generated to prevent the yarn from freely unwinding, to prevent the formation of kinks, to improve sliding in the parts of the head involved in transport, and ultimately to make the introduction into the splicer more efficient and ensure better repeatability of the cycle;
3. While restarting the winding, a small amount of tension should be generated so as to unwind any kinks already formed.
The kink prevention systems of the prior art comprise brushes that preferably rest on two areas spaced at about 180° on the circumference of the tip of the tube; or are composed of shaped ferrules (as per the applicant's patents EP0275596B1 and EP0909736B1 ) that are supported on a portion of the outer circumference of the tube. The support is normally near the top of the bobbin cone.
The slight tension on the yarn is generated in the following way: the yarn that unwinds from the bobbin cone finds the obstacle of the brushes (ferrule) that forces it to pass between the brushes (ferrule) and the tube, which generates a friction and therefore a small tension sufficient to clear any kinks that may have formed; the kink prevention devices are kept in contact with the tube even during the transport of the bobbin yarn by the bobbin nozzle in order to maintain a slight tension favorable to the introduction into the splicer and during a portion of the startup ramp to clear kinks as mentioned above.
More specifically, in the known solutions for the yarn clearer cutting, the kink prevention device is brought into contact with the tube in the shortest possible time, to stop the unwinding of the yarn by inertia.
Therefore, the kink prevention device must be light, and its actuation system must be fast; by remaining in contact with the tube during the suction of the yarn by the bobbin nozzle and during the transport of the yarn to the splicer, the kink prevention device generates a slight tension that is useful for the correct insertion of the yarn into the splicer; lastly, the kink prevention device generates a slight tension during the winding restart ramp. It is then removed from the tube at a certain, generally adjustable, stage of the winding restart acceleration in order to avoid overstressing according to the count, the weak points, and the speed of the yarn.
Common defects of the current kink prevention devices are essentially the following two. On the one hand, known devices are necessarily slow-acting and therefore do not totally prevent the formation of kinks/loops. The reason for this is that, since they have to be some distance from the tip of the tube to avoid interfering with the balloon and creating a surface for collecting dust and have to rest on the tube with limited force to avoid damaging the yarn, their relative operating time is not very short.
Also, the slight tension given to the yarn is not stable and smooth. In fact, it fluctuates between a maximum and a minimum because, in the case of a shaped ferrule, the sliding of the yarn between the ferrule and the tube takes place only over a small portion of the tube once during each turn of the unwinding of the yarn; in the case of brushes, the sliding takes place twice in a turn, but in no case is the tension maintained during the entire unwinding turn. This intermittent lack of tension in the yarn is not conducive to the complete elimination of kinks and leads to irregularities in the introduction of the yarn into the splicer.
Therefore, the problem to be solved is, on the one hand, to have a very quick intervention of the kink prevention device in order to limit unwinding by inertia, and on the other, to substantially improve the slight tension on the yarn, making it stable and regular beginning from the yarn clearer cutting until rewinding.
Thus, it would be desirable to have a kink prevention device which applies a slight, regular tension to the yarn throughout the unwinding turns of the yarn, from the time of the yarn clearer cutting to a predetermined stage of the winding restart acceleration ramp.
On the other hand, it is difficult to achieve this function by acting on the circular tip of the bobbin tube, because the required regularity could only be given by a device that spans the whole 360° of the periphery of the tube tip. Therefore, the device:
1) should be placed near the tip of the bobbin in order to operate quickly; however, to avoid excessive bulk, it would have a complex design;
2) its placement near the unwinding area of the yarn is however contraindicated because it risks collecting dust.

DISCLOSURE OF THE INVENTION

Thus, there is a need to resolve the cited drawbacks and limitations in reference to the prior art.
This need is satisfied by a kink prevention device according to claim 1.

DESCRIPTION OF THE DRAWINGS

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

Fig. 1a depicts a partial plan view of a ferrule-based kink prevention device of the prior art;
Fig. 1b depicts a plot of the trend of the tension generated on the yarn by the kink prevention device of Fig. 1a;
Fig. 2a depicts a partial plan view of a brush-based kink prevention device of the prior art;
Fig. 2b depicts a plot of the trend of the tension generated on the yarn by the kink prevention device of Fig. 2a;
Fig. 3 depicts a cross-sectional side view of a kink prevention device according to an embodiment of the present invention, wherein the presser element is in a retracted configuration;
Fig. 4 depicts a cross-sectional side view of the kink prevention device of Fig. 3, wherein the presser element is in an extracted configuration;
Fig. 5 depicts a view of the kink prevention device of Fig. 3, in a retracted configuration;
Fig. 6 depicts a schematic view of a winding machine comprising a kink prevention device according to the present invention.

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

DETAILED DESCRIPTION

With reference to the aforesaid figures, an overall schematic view of a kink prevention device according to the present invention has been indicated collectively with 4.
In particular, the kink prevention device 4 fits into a winding machine 8 wherein the yarn 12 intercepted by the kink prevention device 4 unwinds from a bobbin 16 to be wound back onto a reel 20, in a known manner.
The kink prevention device 4 comprises a presser element 24, movable along a transverse direction of actuation T-T from a rearward position to a forward position according to an actuation stroke.
The presser element 24 has a rod 28 operatively connected to actuation means 32 and a head 36 associated with the rod 28 and shaped to exert a pressure and friction action on the yarn 12.
The actuation means 32 of the presser element 24 may be pneumatic, electric, magnetic, or hydraulic actuation means.
Said actuation stroke of the presser element 24 is preferably less than or equal to 15 mm. In this way, the actuation time of the presser element is particularly short.
The kink prevention device 4 further comprises a striker 40, separate from and opposed to the presser element 24 along said transverse direction of actuation T-T, on the opposite side of a receiving volume 44 of the associated yarn 12, whereby the yarn 12 is located between the head 36 and the striker 40.
The striker 40 is in turn provided with an end stop wall 48 that defines an end stop of the forward position of the presser element 24.
Advantageously, the kink prevention device 4 comprises a closed loop element 52 that surrounds and accommodates the yarn 12, limiting its movement in a transverse plane perpendicular to said yarn 12.
The closed loop element 52 is preferably encompassed in a balloon breaker device 56 located upstream of the presser element 24 and the striker 40 relative to a direction of advancement S-S of the yarn 12 from a bobbin 16 toward a reel 20.
Preferably, the closed loop element is arranged upstream of the presser element 24 and the striker 40 relative to a direction of advancement S-S of the yarn 12 from the bobbin 16 toward the reel 20.
According to an embodiment, said closed loop element 52 is a ring having a circular cross section.
The head 36 of the presser element 24 has a width 60, measured perpendicular to the transverse direction of actuation T-T, greater than or equal to the lateral extension 64 of the closed loop element 52. In the case wherein the closed loop element 52 has a circular shape, said lateral extension 64 is equal to the diameter of the circle of said closed loop.
The striker, in turn, has a stop width 68, measured perpendicular to the transverse direction of actuation T-T, that is greater than or equal to the lateral extension 64 of the closed loop element 52.
Preferably, the head 36 of the presser element 24 is an element that ends with a flat wall 72, perpendicular to the transverse direction of actuation T-T.
In turn, said end wall 48 of the striker 40, according to an embodiment, is flat and perpendicular to the transverse direction of actuation T-T of the head 36 of the presser element 24.
According to a possible embodiment, the striker 40 is provided with elastic cushioning means 76 along said transverse direction of actuation T-T.
According to an embodiment, the head 36 is provided with elastic cushioning means 76 along said transverse direction of actuation T-T.
According to a possible embodiment, the head 36 is provided with elastic return means 80 that counteract the action of the actuation means 32 to return the presser element 24 to a rearward or resting position.
As mentioned above, the kink prevention device 4 comprises a closed loop element 52 that surrounds and accommodates the yarn 12, limiting its movement in a transverse plane perpendicular to said yarn 12.
According to a preferred embodiment, the winding machine 8 comprises a balloon breaker device 56 of the yarn 12 having a tubular configuration, and said balloon breaker device 56 ends, on the side of the reel 20 and the kink prevention device 4, with said closed loop element 52.
In other words, the closed loop element 52 is enclosed in the top of the balloon breaker device 56.
Preferably, the balloon breaker device 56 therefore has, on the side of the reel 20, a circular neck that acts as a closed loop element 52.
The operation of the kink prevention device according to the present invention will now be described.
As shown, the solution according to the present invention is to achieve the kink prevention function no longer at the circular tip of the bobbin tube, as in the known solutions, but in another area of the winding head, wherein it is possible to quickly stop and generate friction on the yarn on surfaces that ensure a control of the yarn positioning and generate tension without the drawbacks of the prior art.
The present embodiment is in effect located just above the unwinding area, immediately after the balloon breaker device 56, which is the first control member of the yarn 12.
In this position, the actuation of the kink prevention device 4 is extremely fast, since the stroke required to stop the unwinding of the yarn is very short, on the order of 15 millimeters.
Preferably, the kink prevention device 4 is located at the existing yarn presence sensor on the winding head at the outlet of the tube of the balloon breaking device 56, therefore it does not require any additional space in the path of the yarn 12.
In particular, the kink prevention function is delegated to the head or damper 36 of the presser element 24 which is actuated by the actuation means 32, preferably by a pneumatic plunger, so as to abut against the striker 40, preferably spring-loaded with a 15-gram spring.
The stroke of the striker 40 is given by the distance between the retracted position and the extracted position at which the head 36 abuts against the striker 40.
Preferably, the stroke area of the head 36 is located at the outlet of the tube of the balloon breaker device 56, which acts as a closed loop element 52, wherein the segment of yarn 12 on which friction is to be applied after cutting by the yarn clearer is located.
The head or damper 36 moving toward the striker 40 intercepts the yarn 12 and conveys it toward the striker 40 assisted by the circular shape of the closed loop element 52 which guides the yarn 12 to rest on the center of the striker 40, preferably cushioned by the elastic cushioning means 76.
The yarn 12 is thus lightly clamped between the head or damper 36 and the striker 40, and is subject to moderate friction, which is independent of the unwinding of the yarn 12 from the cone of the bobbin 16.
Advantageously, as seen, the yarn 12 is contained within the closed loop element 52 and is therefore always intercepted by the head 36 of the presser element 24 when it moves toward the preferably cushioned striker 40.
Advantageously, the kink prevention device 4 affects the yarn 12 as it unwinds and moves from the bobbin 16 toward the reel 20 so as to generate a continuous tension on the yarn 12 with friction applied between the head 36 and the striker 40: said tension on the yarn 12 is not subject to variations due to the unwinding of the yarn 12, as is the case in the solutions of the prior art.
The tension generated on the yarn 12 is not subject to change due to the unwinding of the yarn because the kink prevention device 4 is positioned outside the unwinding zone of the yarn 12.
As may be appreciated from that which is described above, this invention overcomes the drawbacks of the prior art.
In particular, the present invention provides the following numerous advantages.
First, the actuation of the kink prevention device is immediate, such device being of lightweight manufacturing and having a very short actuation stroke.
In addition, the friction exerted on the yarn is continuous and not pulsed so it is favorable for preventing the formation of kinks in the yarn during suction operations of the yarn end in the unwinding for transporting the yarn to the splicer, and for clearing any kinks that may have formed upon cutting by the yarn clearer.
In particular, the yarn always remains under friction so that the tension generated on the yarn is not subject to variations due to the unwinding of the yarn.
In addition, continuous friction ensures a controlled introduction into the splicer, with lower probability of errors and higher cycle efficiency.
Moreover, the unwinding area is freed from the encumbrance of a device, which, however small it may be, always generates points for collecting dust which, after accumulating over time, may deposit on the yarn and generate defects thereon.
Thus, the kink prevention device according to the present invention is advantageously located outside the yarn unwinding area: in this way, the tension generated on the yarn is not subject to variations due to the unwinding of the yarn.
In addition, the area where the kink prevention device is placed is preferably above the balloon breaker, where the yarn is guided by a tube, and therefore no additional space is needed on the unwinding path of the yarn. Therefore, the kink prevention device according to the present invention may also be applied to existing winding machines (retrofit device).
Furthermore, the kink prevention device according to the invention may also be used in cooperation with a kink prevention device of a known type working on top of the tube.
A person skilled in the art, in order to satisfy contingent and specific needs, may make numerous modifications and variations to the solutions described above, said modifications and variations all being contained within the scope of the invention as defined in the following claims.

Claims

Kink prevention device (4) for a winder comprising:
- a presser element (24), movable along a transverse direction of actuation (T-T) from a rearward position to a forward position according to an actuation stroke, the presser element (24) being fitted with a rod (28), operatively connected to actuation means (32) and a head (36), joined to the rod (28) and shaped so as to exert a pressure and friction action on a yarn (12),

- a striker (40), separate and opposite the presser element (24) along said transversal direction of actuation (T-T), on the opposite side to a receiving volume (44) of the associable yarn (12), so that the yarn (12) is placed between the head (36) and the striker (40),

- wherein the striker (40) is provided with an end stop wall (48) which defines an end stop of the forward position of the presser element (24).
The kink prevention device (4) according to claim 1, wherein the kink prevention device (4) comprises a closed loop element (52) which surrounds and houses the yarn (12), limiting its movements on a transverse plane, perpendicular to the yarn (12) itself.
The kink prevention device (4) according to claim 2, wherein said closed loop element (52) is incorporated into a balloon breaking device (56) placed upstream of the presser element (24) and the striker (40) with respect to a direction of advancement of the yarn (S-S) from a bobbin (16) to a reel (20).
The kink prevention device (4) according to claim 2 or 3, wherein said closed loop element (52) is arranged upstream of the presser element (24) and the striker (40), with respect to a direction of advancement of the yarn (S-S) from a bobbin (16) to a reel (20).
The kink prevention device (4) according to claim 2, 3, or 4, wherein said closed-loop element (52) is a loop with a circular cross-section.
The kink prevention device (4) according to any of the claims from 2 to 5, wherein the head (36) has a width (60), measured perpendicular to the transversal direction of actuation (T-T), greater than or equal to the lateral extension (64) of the closed loop element (52).
The kink prevention device (4) according to any of the claims from 2 to 6, wherein the striker (40) has a stop width (68), measured perpendicular to the transversal direction of actuation (T-T), greater than or equal to the lateral extension (64) of the closed loop element (52) .
The kink prevention device (4) according to any of the claims from 1 to 7, wherein the head (36) is an element ending with a flat wall (72), perpendicular to the transversal direction of actuation (T-T).
The kink prevention device (4) according to any of the claims from 1 to 8, wherein said end stop wall (48) is flat and perpendicular to the transversal direction of actuation (T-T) of the head (36) of the presser element (24) .
The kink prevention device (4) according to any of the claims from 1 to 9, wherein the striker (40) is fitted with elastic cushioning means (76) along said transversal direction of actuation (T-T).
The kink prevention device (4) according to any of the claims from 1 to 10, wherein the head (36) is fitted with elastic cushioning means (76) along said transversal direction of actuation (T-T).
The kink prevention device (4) according to any of the claims from 1 to 11, wherein the head (36) is provided with elastic return means (80) which oppose the action of the actuation means (32) to return the presser element (24) to a rearward position.
The kink prevention device (4) according to any of the claims from 1 to 12, wherein the actuation means (32) of the presser element (24) are pneumatic, electric, magnetic or hydraulic actuation means.
The kink prevention device (4) according to any of the claims from 1 to 13, wherein said actuation stroke of the presser element (24) is less than or equal to 15 mm.
Winding machine (4) comprising a kink prevention device according to any of the claims from 1 to 14, wherein the yarn (12) intercepted by the kink prevention device (4) is unwound from a bobbin (16) to be rewound on a reel (20), wherein said winding machine comprises a balloon breaking device (56) of the yarn (12), having a tubular configuration, said balloon breaking device (56) ending, on the side of the reel (20) and the kink prevention device (4), with said closed loop element (52) .
The winding machine (8) according to claim 15, wherein the balloon breaking device (56) has a circular neck, on the reel side (20), which acts as a closed loop element (52).
Method of removing kinks of yarn (12) in a winding machine (8) comprising the steps of:
- providing a winding machine (8) according to claim 15 or 16,

- actuating the kink prevention device (4) on the yarn (12) which unwinds and runs from the bobbin (16) towards the reel (20), so as to generate a continuous tension on the yarn (12), rubbed between the head (36) and the striker (40), said tension not being subject to variations due to the unwinding of the yarn (12).
The method according to claim 17, comprising the step of positioning the kink prevention device (4) outside the unwinding area of the yarn (12) so that the tension generated on the yarn (12) is not subject to variations due to the unwinding of said yarn (12).