AIR-JET TYPE SPINNING DEVICE

Abstract

 An air-jet type spinning device (4) comprising a body (8) at least partially hollow that delimits a spinning chamber (12), a fiber feeding device (16) facing said spinning chamber (12)) to feed the fibers into the spinning chamber (12), a spinning spindle (20) at least partially inserted into the spinning chamber (12) and provided with a spinning channel (24) for the transit of yarn obtained from said fibers, the spinning channel (24) having a main axis defining a spinning direction (X-X) and having a front input (28) for introducing the fibers into said spinning channel (24). Advantageously, the body (8) comprises at least one upper crown of holes (32) comprising at least two upper injection holes (36) which input an upper flow rate of air in the spinning chamber (12). Furthermore, the body (8) comprises at least one lower crown of holes (40) comprising at least two lower injection holes (44) which input a lower air flow into the spinning chamber (12), wherein said crowns of upper and lower holes (32,40) are fluidically connected to distinct air supplies. The upper injection holes (36) extend into the spinner chamber (12) at a first point (48) upstream of the front input (28), with respect to a direction of advancement (F) of the yarn in the spinning channel (24), wherein the lower injection holes (44) extend into the spinning chamber (12) at a second point (56) downstream of the front input (28), with respect to a direction of advancement (F) of the yarn in the spinning channel (24).

Description

[0001] The present invention relates to an air-jet type spinning device.

STATE OF THE ART

[0002] As is well known, air-jet type spinning devices produce yarn starting from a fiber ribbon.

[0003] This ribbon is subjected to the action of compressed air-jets that allow the outer fibers to open and wrap around the central ones and form the yarn.

[0004] The known solutions present some drawbacks and limitations.

[0005] In fact, there are usually 4 or more holes for compressed air injection that require considerable air consumption with increased energy consumption and therefore an increase in yarn production costs.

[0006] In addition, the known solutions, in order to obtain good quality yarns and to limit the consumption of compressed air, require the production of small spinning chambers. In this way, however, the chambers are extremely susceptible to the presence of dirt and fibers that compromise the quality, reproducibility and strength of the yarn.

[0007] In addition, the known solutions involve certain structural limits in the production of the spinning chamber given that the compressed air jets must be directed in an extremely precise way near the tip of the spinning spindle: in other words, the jets must be directed in a tangential direction and inclined downward to obtain the necessary whirling motion of the compressed air, which must, on the one hand, wrap the outermost fibers around the innermost ones, and on the other, create the vacuum necessary to suction the fibers inside the spinning spindle.

[0008] Despite these geometric constraints, the known solutions do not always guarantee control of the direction of the compressed air jets within the spinning chamber given that the air, once it is released from the nozzles, propagates freely within the spinning chamber and is therefore subject to deviations due to the presence of impurities, such as fibers and dirt, as well as the presence of turbulence and vorticity.

[0009] The prior art solutions do not allow the operating conditions of the spinning device and, in particular, the working conditions within the spinning chamber to be varied accurately: such variability in spinning conditions, as seen, contributes to a poor reproducibility of the quality of the yarn produced.

[0010] In conclusion, the known solutions of air-jet type devices involve considerable consumption of compressed air and high production costs and do not always guarantee the consistency and reproducibility to obtain a high-quality and strong yarn.

PRESENTATION OF THE INVENTION

[0011] The need is therefore perceived to resolve the drawbacks and limitations cited with reference to the known art.

[0012] This requirement is satisfied by an air-jet type spinning device according to claim 1.

DESCRIPTION OF THE FIGURES

[0013] Further features and advantages of the present invention will become more understandable from the following description of its preferred and non-limiting embodiments, wherein:

figure 1 is a sectional perspective view of an air-jet type spinning device according to an embodiment of the present invention;

figure 2 is a sectional view of an enlarged detail of the air-jet type spinning device of figure 1 from a different perspective with respect to said figure 1;

figure 3 is a further sectional view of the air-jet type spinning device of figure 1;

figure 4 is a sectional perspective view of the air-jet type spinning device of figure 3 along the cross-sectional plane IV-IV of figure 3;

figure 5 is a sectional view of the air-jet type spinning device of figure 3, along the cross-sectional plane V-V of figure 3;

figure 6 is a plan view of the air-jet type spinning device of figure 3 from the side of the arrow VI of figure 3.

[0014] The elements or parts of elements in common between the embodiments described hereinafter will be indicated with the same numerical references.

DETAILED DESCRIPTION

[0015] With reference to the aforementioned figures, at 4 is collectively indicated an air-jet type spinning device comprising at least one partially hollow body 8 delimiting a spinning chamber 12 and a fiber feeding device 16 facing said spinning chamber 12 so as to feed the fibers into the spinning chamber 12.

[0016] The air-jet type spinning device 4 further comprises a spinning spindle 20, at least partially inserted into the spinning chamber 12, and provided with a spinning channel 24 for the transit of yarn obtained from said fibers. The spinning channel 24 has a main axis defining a spinning direction X-X and has a front input 28 for introducing the fibers into said spinning channel 24.

[0017] Advantageously, the body 8 comprises at least one upper crown of holes 32 comprising at least two upper injection holes 36 which input a higher air flow rate into the spinning chamber 12; the body 8 further comprises at least one lower crown of holes 40 comprising at least two lower injection holes 44 which input a lower air flow rate into the spinning chamber 12.

[0018] Preferably, but not necessarily, said upper 32 and lower 40 crowns of holes are circular around the spinning direction X-X.

[0019] Said upper 32 and lower 40 crowns of holes are fluidically connected to separate air supplies.

[0020] 'Separate air supplies' is intended to mean that the air supplies of said crowns of holes 32,40 are independent of each other; in other words it is possible to supply the upper and lower crowns of holes 32,40 individually and/or simultaneously. In addition, the air flow rates supplied to the upper and lower crowns of holes 32,40 are independent of each other and may be modified according to the need for spinning as further described below.

[0021] In particular, the upper injection holes 36 open into the spinning chamber 24 at a first point 48 upstream of the front input 28, relative to a direction of advancement F of the yarn in the spinning channel 24.

[0022] Obviously, each upper injection hole 36 opens into the spinning chamber 24 at its corresponding first point 48; in other words, the first point is not common to the separate upper injection holes 36.

[0023] The first points 48 of the upper injection holes 36 may be arranged all at the same distance from the front input 28 or may also be arranged at distances different from the same front input 28.

[0024] A main axis P' of the upper injection holes 36 intersects the main axis at a point S that is distant from said front input 28, relative to the spinning direction X-X, by an upper portion 52 between 0 mm and 4 mm.

[0025] The upper portions 52 identified by the upper injection holes 36 may be the same or different from each other.

[0026] Preferably, the upper injection holes 36 have a width between 0.5 mm and 0.8 mm.

[0027] By 'width' is meant the lumen of the hole, typically, but not necessarily, circular. In the case of a non-circular hole, 'width' is intended to mean the average width of said lumen.

[0028] Preferably, with respect to a cross-sectional plane parallel to and passing through the main axis, a projection of a main axis P' of said upper injection holes 36 identifies, with a transverse direction R-R perpendicular to the spinning direction X-X, an angle α of 5 to 25 degrees.

[0029] The lower injection holes 44 open into the spinning chamber 12 at a second point 56 downstream of the front input 28, with respect to a direction of advancement F of the yarn in the spinning channel 24.

[0030] Obviously, each lower injection hole 44 opens into the spinning chamber 24 in a corresponding second point 56 thereof; in other words, the second point 56 is not common to the separate lower injection holes 44.

[0031] The second points 56 of the lower injection holes 44 may be arranged all at the same distance from the front input 28 or may also be arranged at distances different from the same front input 28.

[0032] A main axis P' of the lower injection holes 44 intersects the main axis at a point I that is distant from said front input 24, relative to the spinning direction X-X, by a lower portion 60 between 0.5 mm and 3.5 mm.

[0033] The lower portions 60 identified by the lower injection holes 44 may be the same or different from each other.

[0034] Preferably, the lower injection holes 44 have a width between 0.7 mm and 1.1 mm.

[0035] By 'width' is meant the lumen of the hole, which is typically, but not necessarily, circular. In the case of a non-circular hole, 'width' is intended to mean the average width of said lumen.

[0036] Preferably, with respect to a cross-sectional plane parallel to and passing through the main axis, a projection of a main axis P" of said lower injection holes 44 identifies with a transverse direction R-R, perpendicular to the spinning direction X-X, an angle β between 20 and 40 degrees.

[0037] The upper injection holes 36 and/or the lower injection holes 44 are supplied at a pressure of between 3 bar and 5.5 bar.

[0038] Preferably, the upper injection holes 36 are supplied with a smaller mass flow of air relative to the lower injection holes 44.

[0039] According to an embodiment of the present invention, with respect to a cross-sectional plane perpendicular to the main axis of the spinning channel 24, projections of said upper injection holes and/or lower injection holes are directed along tangential directions T, tangent to a cylindrical side wall 64 of said spinning chamber 12.

[0040] Preferably, said tangential directions T are all rotated in the same direction along the cylindrical side wall 64 of said spinning chamber 12.

[0041] In this way, all the upper and lower injection holes 36,44 contribute to generate an air flow that wraps the fibers in the same direction of rotation around the spinning direction X-X.

[0042] According to one embodiment of the present invention, the upper crown of holes 32 comprises three upper injection holes 36 equally spaced at 120 degrees relative to a projection plane perpendicular to the spinning direction X-X; furthermore, according to an embodiment of the present invention, the lower crown of holes 40 comprises three lower injection holes 44 equally spaced at 120 degrees relative to a projection plane perpendicular to the spinning direction X-X.

[0043] Preferably, said upper and lower crowns of holes 32,40 are angularly staggered by 60 degrees relative to a projection plane perpendicular to the spinning direction X-X; each of said upper and lower crowns of holes 32,40 has upper and lower injection holes 36,44 equally spaced at 120 degrees relative to a projection plane perpendicular to the spinning direction X-X.

[0044] As mentioned above, the spinning chamber 12 has collectively a circular cross-section relative to a cross-sectional plane perpendicular to said spinning direction X-X.

[0045] The spinning spindle 20 generally has a truncatedcone shape with circular and axial symmetrical cross-section relative to said spinning direction X-X; in particular, the spinning spindle is tapered to the front input 28. An upper portion 68 of the spinning spindle 20 surrounding the front input 28 is suitably rounded and milled to favor the winding of fibers to be twisted to form the yarn.

[0046] According to one possible embodiment of the present invention, the fiber feeding device 16 comprises a needle 72, at least partially interpenetrating into said spinning chamber 12 and axially opposed to said front input 28, so as to create a guide for the fibers being spun.

[0047] As may be appreciated from the foregoing, the air-jet type spinning device according to the invention allows the drawbacks presented in the prior art to be overcome.

[0048] In particular, the present invention may lead to a reduction in air consumption relative to the prior art solutions, given that the total air flow rate is metered and optimized in all of the device's operating conditions in a separate and independent way between the at least two crowns of delivery holes. In this way it is possible, for example, to increase the flow rate sent by one of the two crowns of holes without having to necessarily increase the flow rate over the other, as would be the case with known prior art solutions having a single supply common to all the injection holes.

[0049] Due to the double crown of injection holes, it is possible to better manage the movements of air in the spinning chamber relative to the rotating movement, which is necessary for winding or twisting the fibers, which for the downward movement, i.e. toward the spinning spindle, is necessary for the final spinning.

[0050] The separation of the two crowns of injection holes allows the two air flow rates to be specialized and thus optimized: the upper flow rate, i.e. emitted by the upper crown of holes, will have a limited inclination angle and therefore may confer a high rotation to the fibers while the lower flow rate, i.e., emitted by the lower crown of holes, will have a higher inclination angle to provide a considerable fiber opening force on the spinning spindle. Therefore, the upper flow rate has the main task of conferring the twist of the fibers, due to the high speed tangential component, while the lower flow rate has the primary task of opening the fibers.

[0051] The separate supply of the two injector crowns of holes allows one to adjust, and thus optimize, the two flow rates, and therefore the two effects of twisting and pushing the fibers downwards, in an independent manner: In this way, the independent adjustments allow the spinning process to be adapted to different fibers, counts, lengths, environmental conditions, and so on.

[0052] Unlike the known solutions, it is also possible to input the compressed air above the fibers' point of entry in the spinning chamber, as the air flow does not "disturb" the input fibers directly.

[0053] This is a further advantage, given that interference between the fibers and the air are avoided and therefore the spinning process is more controllable, so as to obtain a yarn with as consistent and reproducible characteristics as possible.

[0054] A person skilled in the art, in the object of satisfying contingent and specific requirements, may make numerous modifications and variations to the air-jet type spinning device described above, all of which are within the scope of the invention as defined by the following claims.

Claims

1. Air-jet type spinning device (4) comprising

- a body (8) at least partially hollow which delimits a spinning chamber (12),

- a fiber feeding device (16), facing said spinning chamber (12) so as to feed the fibers into the spinning chamber (12),

- a spinning spindle (20) at least partially inserted in the spinning chamber (12) and fitted with a spinning channel (24) for the transit of yarn obtained from said fibers, the spinning channel (24) having a main axis which defines a spinning direction (X-X), and having a front input (28) for the introduction of the yarn in said spinning channel (24),

characterized in that

- the body (8) comprises at least one upper crown of holes (32) comprising at least two upper injection holes (36) which input a higher flow rate of air in the spinning chamber (12),

- the body (8) comprises at least one lower crown of holes (40) comprising at least two lower injection holes (44) which input a lower flow rate of air in the spinning chamber (12),

- wherein said upper and lower crowns of holes (32,40) are fluidically connected to separate air supplies,

- wherein the upper injection holes (36) open into the spinning chamber (12) at a first point (48) upstream of the front input (28), with respect to a direction of advancement (F) of the yarn in the spinning channel (24),

- wherein the lower injection holes (44) open into the spinning chamber (12) at a second point (56) downstream of the front input (28), with respect to a direction of advancement (F) of the yarn in the spinning channel (24).

2. Air-jet type spinning device (4) according to claim 1, wherein a main axis (P') of the upper injection holes (36) intersects the main axis at a point (S) that is distant from said front input (28), with respect to the spinning direction), by an upper portion (52) between 0 mm and 4 mm.

3. Air-jet type spinning device (4) according to claim 1 or 2, wherein said upper injection holes (36) have a width varying between 0.5 mm and 0.8 mm.

4. Air-jet type spinning device (4) according to any of the claims from 1 to 3 wherein, with respect to a cross-sectional plane parallel to and passing through the main axis, a projection of a main axis (P') of said upper injection holes (36) identifies with a transverse direction (R-R), perpendicular to the spinning direction (X-X), an angle (α) of between 5 and 25 degrees.

5. Air-jet type spinning device (4) according to any of the preceding claims, wherein a main axis (P") of the lower injection holes (44) intersects the main axis at a point (I) that is distant from said front input (28), with respect to the spinning direction), by a lower portion (60) between 0.5 mm and 3.5 mm.

6. Air-jet type spinning device (4) according to any of the preceding claims, wherein said lower injection holes (44) have a width varying between 0.7 mm and 1.1 mm.

7. Air-jet type spinning device (4) according to any of the preceding claims wherein, with respect to a cross-sectional plane parallel to and passing through the main axis, a projection of a main axis (P") of said lower injection holes (44) identifies with a transverse direction (R-R), perpendicular to the spinning direction (X-X), an angle (β) of between 20 and 40 degrees.

8. Air-jet type spinning device (4) according to any of the preceding claims, wherein said upper injection holes (36) and/or lower injection holes (44) are fed with a pressure between 3 bar and 5.5 bar.

9. Air-jet type spinning device (4) according to any of the preceding claims, wherein said upper injection holes (36) are fed with a smaller mass flow of air than the lower injection holes (44).

10. Air-jet type spinning device (4) according to any of the preceding claims, wherein, with respect to a cross-sectional plane perpendicular to the main axis of the spinning channel (24), projections of said upper injection holes (36) and / or lower injection holes (44) are directed along tangential directions (T), tangent to a cylindrical side wall (64) of said spinning chamber (12).

11. Air-jet type spinning device (4) according to claim 10, wherein said tangential directions (T) are all rotated in the same direction along the cylindrical side wall (64) of said spinning chamber (12).

12. Air-jet type spinning device (4) according to any of the preceding claims, wherein the holes of the upper crown (32) comprises three upper injection holes (36) equally spaced at 120 degrees from each other with respect to a projection plane perpendicular to the spinning direction (X-X), and wherein the lower crown of holes (40) comprises three lower injection holes (44) equally spaced at 120 degrees from each other with respect to a projection plane perpendicular to the spinning direction (X-X).

13. Air-jet type spinning device (4) according to claim 12, wherein said upper and lower crowns of holes (32, 40) are angularly staggered by 60 degrees from each other with respect to a projection plane perpendicular to the spinning direction (X-X).

14. Air-jet type spinning device (4) according to any of the preceding claims, wherein the spinning chamber (12) has overall a circular cross-section with respect to a cross-sectional plane perpendicular to said spinning direction (X-X).

15. Air-jet type spinning device (4) according to any of the preceding claims, wherein the spinning spindle (20) has overall a truncated cone shape with a circular and axially symmetric cross-section which, with respect to said spinning direction (X-X), the spinning spindle tapering towards the front input (28).

16. Air-jet type spinning device (4) according to any of the preceding claims, wherein the fiber feeding device (16) comprises a needle (72), at least partially penetrated in said spinning chamber (12) and axially opposed to said front input (28), so as to create a guide for the fibers being spun.

Drawing