Patent Application
20150329994
The present invention refers to a spinning unit of an air jet spinning machine with a spinning nozzle to manufacture yarn from a fiber strand fed to the spinning nozzle, whereby the spinning nozzle has an inlet for the fiber strand, an internally located swirl chamber, a yarn forming element protruding into the swirl chamber and a exhaust duct for the yarn forming element containing the yarn as well as an outlet for the yarn produced inside the spinning nozzle. In addition, a process for operating an air jet spinning machine with at least one spinning unit is suggested, whereby the spinning unit has at least one spinning nozzle and a fiber strand is fed to the spinning nozzle through an inlet while the spinning unit is being operated, and a twist is imparted to the fiber strand in the area of a yarn forming element protruding into a swirl chamber of the spinning nozzle, so that a yarn is formed from the fiber strand exiting the yarn forming element through a exhaust duct and finally comes out through an outlet.
Air jet spinning machines equipped with the corresponding spinning units are known from the state of the art and serve to manufacture yarn from an elongated fiber strand. In this process, the outer fibers of the fiber strand are wound around the inner core fibers with the help of a swirled air current generated by the air nozzles inside the swirl chamber in the area of a fiber inlet of the yarn forming element and finally form the wrap fibers crucial for desired yarn strength. As a result of that, a yarn with a real yarn twist is formed that is finally led out of the swirl chamber via an exhaust duct and can be wound up around a tube, for example.
Generally, within the meaning of the invention, the term yarn is understood to be a fiber strand in which at least some of the fibers are wound around an inner core. Thus, the term encompasses a yarn in the conventional meaning that can be processed to a fabric, for example, with the help of a weaving machine. However, the invention also refers to air jet spinning machines used to manufacture so-called rove (another name: sliver). This kind of yarn is characterized by being capable of stretching in spite of having certain strength sufficient for transporting the yarn to a subsequent textile machine. Thus, the rove can be stretched with the help of a stretching mechanism (e.g. the drafting equipment, a textile machine that processes the rove such as a ring spinning machine) before it is finally spun.
In the manufacturing of synthetic fibers such as polyester or a combination of natural and synthetic fibers, deposits are formed on the surface of the yarn forming element. The manufacturing of synthetic fibers encompasses a so-called preparation of the continuous filaments during the manufacturing process. The preparation consists of applying a preparation agent (generally oils with various additives) to allow treatment that can involve stretching the continuous filaments under high rates. These preparation agents continue to adhere partially on the synthetic fibers even in further processing and cause impurities in the air jet spinning machine. The fibers fed to the air jet spinning machine in form of a fiber strand are generally supplied by a pair of delivery rollers of the spinning nozzle. The pair of delivery rollers can correspond to a front roller pair of drawing equipment, which is used to improve the fiber strand presented before it enters the spinning nozzle.
As a rule, a fiber guiding element is arranged in the inlet area of the spinning nozzle through which the fiber strand is guided into the spinning nozzle and finally into the area of the yarn forming element. Spindles having an inner exhaust duct are used most of the time as yarn forming elements. Compressed air is introduced in such a way on the top of the yarn forming element through the housing wall of the spinning nozzle that the above-mentioned rotating swirled air current is generated. This causes the individual outer fibers coming out of the fiber guiding element to be severed and turned over above the tip of the yarn forming element. Later, these detached fibers rotate on the surface of the yarn forming element. Subsequently, the forward movement of the inner core fibers of the fiber strand makes the rotating fibers wind around the core fibers, thus forming the yarn. However, the movement of the individual fibers over the surface of the yarn forming element also causes deposits to form on the yarn forming element owing to adhesions on the fibers from the manufacturing process. Deposits on the yarn forming element can also be caused by damaged fibers. For the same reasons, deposits can also form on the surface of the spinning nozzle's interior. These adhesions are detrimental to the surface finish of the yarn forming element and lower the quality of the manufactured yarn. Therefore, regular cleaning of the affected surfaces becomes necessary to maintain the same quality of the spun yarn.
The surfaces of the yarn forming element can be cleaned manually by periodically disassembling the yarn forming element, but this involves significant maintenance work coupled with the corresponding operational downtime.
On the other hand, EP 2 450 478 describes an equipment capable of cleaning the machine automatically without shutting down the machine. To accomplish this, an additive is added to the compressed air used inside the spinning nozzle for producing the swirled air current. The additive is guided through the compressed air towards the yarn forming element, where it cleans its surface.
Another embodiment to clean the yarn forming element is described in JP-2008-095-208. Here, an additive is likewise fed to the compressed air used for swirling in the spinning nozzle that guides it to the spinning nozzle and thus to the yarn forming element. In the disclosed embodiment, the dosage and addition of the additive is intended to be separate for each spinning unit.
The disadvantage of these disclosed cleaning systems is that the additive dosage depends on the supply of compressed air to the air nozzles. Thus, a dosage independent of this is not possible.
In principle, the same problem occurs when an additive should be added to the fiber strand in order to improve the properties of the yarn manufactured in this way, for example with regard to its hairiness or strength, since in this case the dosage can be regulated in an especially precise way to prevent that too much or too little of the prescribed quantity of additive is applied on the individual fiber strand sections.
The task of the present invention is therefore to suggest a solution that allows an especially constant and exactly regulated supply of the spinning nozzle with additive.
The task is solved by a spinning unit of an air jet spinning machine and a process having the characteristics of the independent patent claims.
According to the invention, the spinning unit is characterized by having an additive supply assigned to it, designed to supply the spinning nozzle with an additive. The additive supply encompasses at least one additive supply line that is fluidically connected to an additive duct of the yarn forming element. The additive duct ends in the swirl chamber of the spinning nozzle or in the exhaust duct of the yarn forming element, so that an additive introduced into the additive duct via the additive supply line can be introduced into the exhaust duct and/or the swirl chamber.
The result is that the additive can now be introduced into the swirl chamber regardless of the compressed air supplied by the air nozzles, making it possible to supply an exact dose of the additive. Preferably, the additive duct of the yarn forming element ends in the area of the exhaust duct, i.e., it has an additive discharge opening located in the inner wall area of the exhaust duct. In this case, the imaginary extension of a middle axis of the additive duct intersects preferably with the middle axis of the exhaust duct. It is especially advantageous if the additive ends in the exhaust duct, in the area of a tip or fiber inlet opening of the yarn forming element and oriented obliquely against the inlet direction of the fibers in the exhaust duct, in which case the exhaust duct and the additive duct can be executed as a bore (at least partially). Incidentally, the additives used can be liquids, solids or mixtures thereof, but water or an aqueous solution is preferred.
So the quantity of the delivered additive can be regulated, it is also advantageous if the additive supply—especially the additive supply line—is equipped with a dosing device for regulating the volumetric flow and/or mass flow of the additive being delivered via the additive duct. The dosing device can be a valve or a dosing pump regulated manually or through a control mechanism so the quantity of additive passing through the pump or dosing pump can be controlled, in which case the valve or dosing pump is integrated into the additive supply line, for example. Alternately or additionally, the quantity of additive being supplied can also be controlled by adjusting the negative pressure prevalent in the swirl chamber. The negative pressure is generated by a negative pressure source connected to the swirl chamber.
It is also advantageous if the additive duct (or at least some sections thereof) runs inside the yarn forming element. For example, it could be conceivable to execute the additive duct as a bore that penetrates the yarn forming element or its front area having the fiber inlet opening from the outside to the exhaust duct (in which case, more than one additive duct could be generally present). Likewise, the additive duct can consist of several interconnected sections. It could be conceivable, for example, for the yarn forming element to have a base body and a tip fixed to the base body and the above-mentioned fiber inlet opening. In this case, the exhaust duct could be made up of a bore arranged inside the tip and an additional section running inside the base body (although this section could also be formed by a bore). In this case, a preferably annular transition section of the additive duct surrounding the exhaust duct could be located in the transitional area between base body and tip, in which both the duct section of the tip and the duct section of the base body end. This could finally have the advantage that both duct sections are always connected through the transitional section regardless whether the tip is twisted around the middle axis of the exhaust duct.
It is additionally advantageous if the additive duct encompasses with the exhaust duct (especially with its corresponding middle axes) an angle (at least in sections) of 3° to 12°, preferably of 5° to 10°. The additive duct is also oriented preferably against the yarn's transportation direction inside the exhaust duct, so that the additive is delivered (obliquely) against the above-mentioned transportation direction in the exhaust duct and, while doing so, makes contact with the fibers of the supplied fiber strands or yarn. Finally, it is advantageous if at least some sections of the additive duct and exhaust duct lie on a common plane.
It is advantageous if the additive duct ends in the exhaust duct, in an area of a fiber inlet opening of the yarn forming element. In this case, the additive also reaches the area of the outer surface of the yarn forming element and can thus serve to clean this surface (in this case, the negative pressure prevalent in the swirl chamber, which is generated therein when the spinning nozzle is operated by an air exhaust, transports the additive from the exhaust duct and hence from the interior of the yarn forming element in the area of its outer surface). In particular, the additive duct should end in the exhaust duct in such a way that the resulting connection area of additive duct and exhaust duct is less than 10 mm, preferably less than 5 mm, away from the fiber inlet opening of the yarn forming element.
It is likewise advantageous if the additive duct runs, at least partially, inside a wall of the yarn forming element surrounding the exhaust duct and ends in a discharge opening located in the outer surface area of the yarn forming element. In this case, the additive duct does not change gradually into the exhaust duct. Rather, the above-mentioned discharge opening is found preferably in the outer area of the front area of the yarn forming element or its tip that has the fiber inlet opening. Here, the additive is applied directly on the area of the outer surface of the yarn forming element, which during yarn manufacturing makes contact with the fiber ends looped around the inner core of the supplied fiber strands in the fiber inlet opening area of the yarn forming element. Here, the additive also makes contact with the fibers of the outer surface of the yarn forming element, so that—depending on how much additive is added—yarn quality is improved and/or the yarn forming element is cleaned.
It is additionally advantageous if the additive duct is also fluidically connected with a compressed air line of the spinning unit, so that the compressed air introduced through the compressed air line can be introduced into the exhaust duct and/or swirl chamber via the additive duct. The introduction of compressed air is especially advantageous during the start of spinning on the corresponding spinning unit, in which the end of a yarn is introduced against the transportation direction prevailing in the spinning operation through the outlet of the spinning nozzle in the exhaust duct. The compressed air introduced via the additive duct generates in this case an air current inside the exhaust duct directed towards its fiber inlet opening. The introduced yarn end, coming preferably from a bobbin, is captured by the above-mentioned air current during the start of spinning and transported through the exhaust duct. After the yarn end exits the exhaust duct via the fiber inlet opening, it can finally be transported outside via the spinning nozzle inlet (this is also supported by the air current mentioned above, however) and joined to a final section of a fiber strand. Finally, the previously deactivated air nozzles of the spinning nozzle are once again impinged with compressed air and the supply of compressed air coming through the additive duct is stopped, so that the yarn end joined to the fiber strand (and thereby the fiber strand too) reaches the swirl chamber in transportation direction and the spinning operation can resume.
It is especially advantageous if at least one valve is assigned to the compressed air line and/or the additive supply line that can have two different valve positions, whereby the additive duct is fluidically connected either to the compressed air line or the additive supply line depending on the position of the valve. While the first position can be selected over the course of the initial spinning mentioned above, additives can be supplied to the spinning nozzle in the second position and this is advantageous in the spinning operation that follows initial spinning. It could be possible to move the valve manually, for example.
It is likewise extremely advantageous if the valve is connected to a control mechanism designed to keep the valve in its first position, at least part of the time, while the spinning unit is being operated. In this position, the additive duct is fluidically connected to the additive supply line. Likewise, the control mechanism should be executed so the valve can be kept in its second position, at least part of the time, during an initial spinning of the spinning unit. In this position, the additive duct is fluidically connected to the compressed air line. In this case, the control mechanism selects the valve position automatically so that additives are only supplied to the spinning nozzle when no initial spinning is being carried out and vice versa.
The process according to the invention is characterized by the fact that an additive is supplied to the spinning nozzle of the respective sir jet spinning machine while the spinning unit is in operation, at least part of the time, with the help of an additive supply, in which case the added additive is delivered through an additive duct of the yarn forming element in the exhaust duct and/or the swirl chamber. Regarding possible physical features of the air jet spinning machine or its components, refer to the previous or following description. The process can be used in an air jet spinning machine that has one or several of the corresponding features. In particular, different additives can be used depending on the application, but reference is also made here to the description given below. In any case, according to the present invention, the additive is introduced to the spinning nozzle regardless whether during spinning the compressed air is introduced to the spinning nozzle through the air nozzles of the respective spinning nozzle, so that the additive doses can be delivered regardless of the air pressure of the compressed air mentioned above.
It is especially advantageous if during the operation of the spinning unit additives can be delivered, at least part of the time, through the additive duct, and when during an initial operation of the spinning unit compressed air is delivered through the additive duct, at least part of the time. In this case, the additive duct is used either for delivering the additive or compressed air. The delivery of compressed air allows a return of a yarn end from the outlet of the spinning nozzle to an area arranged upstream from the inlet of it. It is especially advantageous if either additives or compressed air is/are delivered via the additive duct depending on the spinning unit's mode of operation.
It is advantageous if the additive duct is fluidically connected with the additive supply line and a compressed air line. In addition, at least one valve should be assigned to the additive supply line and/or the compressed air line, in which case the valve is kept, at least part of the time, in a first position in which the additive duct is fluidically connected to the additive supply line, with the help of a control mechanism while the spinning nozzle is in operation. As an alternative to this, the control mechanism should keep the valve, at least part of the time, in a second position in which the additive duct is fluidically connected to the compressed air line while the spinning nozzle is in operation. The position of the corresponding valve is therefore regulated by the control mechanism, thus allowing an automatic operation of the valve.
It is especially advantageous if the volumetric and/or mass flow of the additive delivered through the additive duct is regulated with the help of a dosing device, which can be a valve or dosing pump, for example, and the valve could be moved to several positions. For more possible details of the dosing device, consult the description given below.
It is likewise advantageous if the volumetric flow rate of the delivered additive reaches, at least part of the time, between 0.001 mL/min and 7.0 mL/min, preferably between 0.01 mL/min and 5.0 mL/min, very preferably between 0.05 and 3.0 mUrnin, and/or when the mass flow of the added additive reaches, at least part of the time, a rate between 0.001 g/min and 7.0 g/min, preferably between 0.01 g/min and 5.0 g/min, very preferably between 0.05 g/min and 3.0 g/min. While higher values (during the cleaning operation) allow the yarn forming element of the spinning nozzle to be cleaned, lower values are advantageous during spinning because the additive serves merely to improve yarn properties. Therefore, a dosing device that delivers the additive should allow the regulation of the volumetric or mass flow over the above-mentioned ranges so the individual spinning nozzles can be operated both during their normal and cleaning operation.
In this context, It is advantageous if the volumetric flow (or mass flow) of the additive added during the normal operation of the air jet spinning machine reaches a value between 0.001 mL/min (or g/min) and 1.5 mL/min (or g/min), preferably between 0.01 mL/min (or g/min) and 1.0 mL/min (or g/min) and the volumetric flow (or mass flow) of the additive added during a cleaning operation of the air jet spinning machine reaches a value between 2.0 ml/min (or g/min) and 7.0 mL/min (or g/min), preferably between 3.0 ml/min (or g/min) and 7.0 mL/min (or g/min).
The exact value can be selected from the spinning unit depending on the properties of the fiber strand and/or its feeding speed in the spinning unit and/or the yarn's reeling speed and can therefore fluctuate depending on the individual application. Likewise, the value can be selected between two cleaning steps depending on how long the cleaning or normal operation lasts.
Additional advantages of the inventions are described in the following embodiments, which show:
In addition, the air jet spinning machine can encompass a pair of draw-off rollers downstream from the spinning nozzle 1 with two draw-off rollers 26 and a winding device 27 downstream from the draw-off roller pair for spooling the yarn 2 that leaves the spinning unit on a tube. The spinning unit according to the invention must not necessarily have drawing equipment 20. The draw-off roller pair is not absolutely necessary either.
The spinning unit works generally according to an air spinning process. To form the yarn 2, the fiber strand 3 is guided with a fiber guiding element 18 through an inlet opening of the inlet 4 mentioned above into the swirl chamber 5 of the spinning nozzle 1, where a twist is imparted to it, i.e. at least a few of the free fiber ends of the fiber strand 3 are grasped by the vortex air flow generated by air nozzles 22 arranged in a swirl chamber wall surrounding the swirl chamber 5 (the air nozzles 22 can be connected to one another by means of an air supply duct 23 that is, in turn, connected to a compressed air line 25 supplied with compressed air via a compressed air supply 29; compare also
Here, some of the fibers are pulled out of the fiber strand 3, at least to some extent, and wound around the front area of a yarn forming element 6 protruding into the swirl chamber 5. Owing to the fact that the fiber strand 3 is drawn from the spinning nozzle 1 through a fiber net opening 32 of the yarn forming element 6 via an exhaust duct 24 arranged inside the yarn forming element 6 from the swirl chamber 5 and finally through an outlet 7 from the spinning nozzle 1, the free fiber ends are finally also pulled towards the fiber inlet opening 32 and in the process twist around as so-called wrap fibers around the centrally running core fibers—resulting in a yarn 2 having the desired twist. The compressed air introduced through the air nozzles 22 finally comes out of the spinning nozzle 1 through the exhaust duct 24 and a possibly present air outlet 21, which can be connected to a negative pressure source if necessary.
Generally speaking, it should be clarified here that the manufactured yarn 2 can be basically any fiber strand 3 characterized by the fact that an outer portion of the fibers (the so-called wrap fibers) twists around an inner, preferably untwisted or if necessary twisted portion of the fibers in order to impart the yarn 2 with the desired strength. Thus, the invention also encompasses an air jet spinning machine used to manufacture so-called rove. The rove is a yarn 2 having a relatively low proportion of wrap fibers or a yarn 2 in which the wrap fibers are twisted relatively loosely around the inner core so that the yarn 2 remains capable of being drawn. This becomes decisive when the manufactured yarn 2 should or must be drawn once again in a subsequent textile machine (e.g. a ring spinning machine) with the help of a drawing equipment be muss so it can be correspondingly processed further.
With regard to the air nozzles 22, it should be mentioned here from a purely precautionary viewpoint that they should generally be aligned in such a way that the air jets emerge with equal alignment in order to generate together an air flow with equal alignment and a direction of rotation. Preferably, the individual air nozzles 22 are here arranged rotationally symmetrical to one another and end tangentially in the swirl chamber 5.
According to the invention,
It is furthermore intended for the additive duct 10 mentioned above to extend at least partially inside the yarn forming element 6, in which case the additive duct 10 can be present as a bore, for example. As can be seen in
Alternately to the embodiment shown in
Finally,
Furthermore, an additive deposit 9 is present, connected fluidically to the connection 30 of the additive duct 10 (shown in
Additionally, another compressed air line 25 can be present (in
So it can be determined whether the additive duct 10 can be supplied with compressed air or additive, it finally makes sense to equip the additional compressed air line 25 and the additive supply line 14 with a valve 11 that allows, depending on its setting, a delivery of additive or compressed air to the common supply line 31 that branches off from the valve 11 (in this case, the supply line 31 can be connected to the above-mentioned connection 30). Finally, the control mechanism 16 is used preferably to set the valve position.
The present invention is not restricted to the embodiments shown and described. Modifications within the framework of the invention are just as possible as any combination of the characteristics described, even if they are shown and described in different parts of the description or claims or in different embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 00716/14 | May 2014 | CH | national |
