Pneumatic spinning device and spinning machine

Abstract

 A pneumatic spinning device includes a nozzle block (34) and a hollow guide shaft body (20). The nozzle block (34) is provided with a depressurized suction chamber and a whirling chamber having a greater peripheral length than that of the depressurized suction chamber. The nozzle block (34) is provided with at least one air injecting nozzle (27). The air injecting nozzle (27) injects compressed air from a nozzle opening (27a) opening into the whirling chamber, thereby generating whirling airflow in the whirling chamber. A fiber passage is formed in the hollow guide shaft body (20). Moreover, the hollow guide shaft body (20) is arranged such that a tip end at an inlet of the fiber passage is located within the depressurized suction chamber. The nozzle opening (27a) is located downstream in a feeding direction of a fiber bundle than the tip end of the hollow guide shaft body (20).

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention mainly relates to a pneumatic spinning device. More particularly, the present invention relates to an arrangement of a spindle and an air injecting nozzle which are provided in the pneumatic spinning device.

2. Description of the Related Art

[0002] Conventionally, there has been known a spinning machine including a pneumatic spinning device for applying twists to fibers by utilizing whirling airflow, thereby producing spun yarn. The pneumatic spinning device of this type includes a spindle and an air injecting nozzle for injecting airflow to generate whirling airflow around the spindle. Fibers subjected to an action of the whirling airflow whirl around the spindle so that twists are applied to the fibers and spun yarn is produced.

[0003] As described above, in the pneumatic spinning device, the fibers are twisted by the whirling airflow, and the spun yarn is produced. Therefore, quality of the spun yarn is greatly influenced by a flowing manner of the whirling airflow. Accordingly, there have been conventionally devised a position of formation of the air injecting nozzle for generating the whirling airflow, a shape of the spindle around which the whirling airflow flows, and the like.

[0004] For example, in a spinning device disclosed in Japanese Unexamined Patent Publication No. 2003-193337, an air injecting nozzle (an air injecting hole) is provided such that air injected from the air injecting nozzle is injected downward in a tangential direction of a round part formed on an upper corner portion of a spindle (a hollow guide shaft body). In this prior art document, the air injected from the air injecting nozzle becomes whirling airflow flowing spirally downward around the hollow guide shaft body.

[0005] Japanese Unexamined Patent Publication No. 3-241021 discloses a structure in which an inclination angle of an air injecting nozzle (a nozzle) is at least 70 degrees and is less than or equal to 90 degrees with respect to an advancing direction of a fiber bundle. This prior art document describes that yarn with a satisfactory number of twists is therefore obtained. With reference to FIG. 2 in this prior art document, an outlet of the air injecting nozzle is located upstream of a tip end of the spindle.

[0006] Japanese Unexamined Patent Publication No. 2008-297687 discloses a structure in which an outlet of an air injecting nozzle (an air nozzle) does not face a reversal chamber (a depressurized suction chamber) (that is, the outlet is formed downstream of a tip end of a spindle). This prior art document states that air injected from the air injecting nozzle is consequently prevented from being diffused rapidly. Moreover, in a spinning machine disclosed in this prior art document, the spindle is cylindrical (has a constant diameter) within a range of a predetermined length from the tip end side, and a cross-sectional area of a whirling airflow generating chamber is constant within the range of the predetermined length. This prior art document states that stable whirling airflow can be applied entirely and the whirling airflow can be generated effectively.

[0007] In the case of the structure in which air is injected in the tangential direction of the round part formed on the upper corner portion of the spindle as in Japanese Unexamined Patent Publication No. 2003-193337, the air injected from the air injecting nozzle may collide with the tip end of the spindle. When the air collides with the hollow guide shaft body, compressed air injected at a high speed expands quickly. For this reason, a flow rate of the compressed air may be reduced, and the whirling air may not be generated in some cases. As a result, reversal fiber cannot be wound around core fiber and the spun yarn cannot be produced in some cases.

[0008] In consideration of a stabilization of a behavior of the reversal fiber and an application of an appropriate tension to the reversal fiber, it is preferable that the reversal fiber is appropriately pushed against the tip end of the spindle. However, in some cases in which the injecting outlet of the nozzle is located upstream of the tip end of the spindle as in Japanese Unexamined Patent Publication No. 3-241021, the reversal fiber may not be pushed against the tip end of the spindle by a force of the compressed air injected from the nozzle depending on the inclination angle of the nozzle. More specifically, with the structure described in this prior art document, the compressed air is injected towards the upstream of the tip end of the spindle when the inclination angle of the nozzle is large (particularly 70° to 90°). Consequently, the reversal fiber cannot be pushed against the tip end of the spindle with the compressed air by a sufficient force. For this reason, with the structure described in this prior art document, the reversal fiber may float up from the tip end of the spindle in some cases. If the reversal fiber thus floats up from the tip end of the spindle as described above, a sufficient tension cannot be applied to the winding fiber when applying twists. Moreover, the floating ends of the reversal fibers may be entangled with one another. As a result, a strength of the produced spun yarn is reduced in some cases.

[0009] In Japanese Unexamined Patent Publication No. 2008-297687, the outlet of the air nozzle is formed downstream of the tip end of the spindle. Accordingly, the reversal fiber may be excessively pushed against the spindle by the force of the compressed air injected from the air nozzle. Consequently, the reversal fiber may be inhibited from being rotated. Moreover, with the structure described in this prior art document, a space between a nozzle block and the spindle is constant. Therefore, the whirling airflow generated by the compressed air injected from the air nozzle is prone to flow towards the downstream. For this reason, as the whirling airflow flows towards the downstream, flow (an axial flow component) of the whirling airflow towards the downstream is increased, and to the contrary, flow (a whirling component) for whirling the reversal fiber by the whirling airflow is reduced rapidly. As a result, a rotating speed of the reversal fiber is reduced in some cases.

SUMMARY OF THE INVENTION

[0010] It is an object of the present invention to provide a pneumatic spinning device capable of enhancing a strength of spun yarn while stabilizing behavior of winding fibers.

[0011] According to a first aspect of the present invention, a pneumatic spinning device for producing spun yarn by whirling fiber of a fiber bundle by whirling airflow includes a depressurized suction chamber section, a whirling chamber section and a spindle. The depressurized suction chamber section has a depressurized suction chamber formed therein. The whirling chamber section has a whirling chamber formed therein. The whirling chamber has a peripheral length which is greater than that of the depressurized suction chamber. The whirling chamber section has at least one air injecting nozzle formed therein. The air injecting nozzle injects compressed air from a nozzle opening opening into the whirling chamber to generate the whirling airflow in the whirling chamber. A fiber passage is formed in the spindle. The spindle is arranged such that a tip end at an inlet of the fiber passage is located within the depressurized suction chamber. The nozzle opening is located downstream than the tip end of the spindle in a feeding direction of the fiber bundle.

[0012] As described above, the nozzle opening is formed into the whirling chamber, and the tip end of the spindle is located within the depressurized suction chamber. Consequently, the compressed air injected from the nozzle opening can be prevented from expanding in proximity of the tip end of the spindle. As a result, reversal fiber can be prevented from floating up at the tip end of the spindle. In other words, the reversal fiber can be stably pushed against the tip end of the spindle by the compressed air. By setting the peripheral length of the depressurized suction chamber to be smaller than that of the whirling chamber, the expanded compressed air hardly flows from the whirling chamber towards the depressurized suction chamber. Consequently, a whirling component of whirling airflow in the depressurized suction chamber is reduced and airflow gently flowing downstream controls the depressurized suction chamber. Accordingly, the fiber is smoothly reversed in the whirling chamber, and an appropriate tension can be stably applied to fiber wound around core fiber. As a result, yarn strength of spun yarn to be produced is enhanced. Furthermore, since the reversal fiber hardly floats up from a surface of the spindle, stable spinning can be carried out even if a whirling speed of the fiber is increased. Consequently, high-speed spinning at a speed of 500 m/min or 600 m/min can be carried out, which could not be implemented by the conventional spinning device (a spinning speed of approximately 250 m/min to 400 m/min).

[0013] In the above pneumatic spinning device, in a cross-section cut through a plane passing through an axial line of the spindle, at least a portion of a cross-sectional contour of an inner wall surface of the whirling chamber section forming the whirling chamber located near the depressurized suction chamber is formed substantially in a curve. Consequently, the wall surface of the whirling chamber located near the depressurized suction chamber has no angular portion. Therefore, a turbulence of airflow can be prevented in the whirling chamber, and the airflow can smoothly flow. As a result, winding fiber can be prevented from being irregularly wound around core fiber or free end of the winding fibers can be prevented from being entangled with one another. Consequently, quality of produced yarn can be stabilized.

[0014] In the above pneumatic spinning device, at least a portion of an opening contour of the nozzle opening is formed on the curved cross-sectional contour among the inner wall surface of the whirling chamber section forming the whirling chamber. By forming at least a part of the nozzle opening on the wall surface having the curved cross-sectional contour, an oval peripheral length of the opening contour of the nozzle opening can be increased. Consequently, compressed air can be injected from the nozzle opening so as to spread into the whirling chamber, and the whirling airflow can be applied to the fiber within a wider range. Thus, the fiber can be efficiently whirled by a great force. Moreover, in the case in which the wall surface of the whirling chamber is formed angular as in the conventional pneumatic spinning device, if the nozzle opening is formed over the angular portion, a shape of the nozzle opening is considerably varied with a slight shift of a forming position, thereby changing the airflow in the whirling chamber. In the case in which the nozzle opening is formed on the angular wall surface, the quality of the yarn to be produced is prone to be influenced by processing precision in the nozzle opening. However, in the case in which the nozzle opening is formed on the wall surface having the curved cross-sectional contour as described above, the shape of an outlet of the injecting nozzle is not greatly changed even if the position in which the nozzle opening is formed is slightly shifted. In other words, by forming the pneumatic spinning device as described above, the quality of the produced yarn can be maintained irrespective of the processing precision in the nozzle opening.

[0015] In the above pneumatic spinning device, when viewed from a direction intersecting with a central axis line of the spindle and intersecting with a longitudinal direction of the air injecting nozzle, the longitudinal direction of the air injecting nozzle is inclined by an angle that is at least 70 degrees and less than or equal to 80 degrees with respect to the central axis line of the spindle. Accordingly, a balance between a speed in a whirling direction and a speed in a fiber feeding direction of the whirling airflow acting on the fiber in the whirling chamber is particularly preferable in high-speed spinning. In other words, the fiber can be whirled at a sufficient speed while suction flow is generated for pulling the fiber downstream in the fiber feeding direction by the compressed air injected from the air injecting nozzle formed as described above. As a result, the strength of the spun yarn to be produced can be enhanced. Furthermore, since the whirling component of the air acting on the fiber is maintained in the whirling chamber, floating short fibers are sequentially caught and wound around the reversal fiber, and a fiber loss can be decreased.

[0016] In the above pneumatic spinning device, a flow path cross-sectional area of a downstream end of the whirling chamber is preferably formed smaller than a flow path cross-sectional area of a position in the whirling chamber where the nozzle opening is formed. Consequently, the whirling airflow can be maintained at high speed until the whirling airflow is discharged from the whirling chamber. In other words, since fiber can be whirled at high speed in the whirling chamber, the strength of the spun yarn to be produced can be enhanced even in high-speed spinning.

[0017] According to a second aspect of the present invention, there is provided a spinning machine including the above pneumatic spinning device and a winding device adapted to wind spun yarn produced by the pneumatic spinning device into a package. Accordingly, even in the case of high-speed spinning, spun yarn having an enhanced strength can be produced, and a package of high quality can be more efficiently formed at a higher speed than in the conventional spinning machine.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 

FIG. 1 is a front view illustrating an entire structure of a spinning machine according to an embodiment of the present invention;

FIG. 2 is a longitudinal cross-sectional view illustrating the spinning machine;

FIG. 3 is a schematic longitudinal cross-sectional view illustrating a pneumatic spinning device;

FIG. 4 is a longitudinal cross-sectional view illustrating a nozzle block;

FIG. 5 is a longitudinal cross-sectional view illustrating a state during spinning; and

FIG. 6 is a schematic longitudinal cross-sectional view illustrating a pneumatic spinning device according to another embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0019] Next, a first embodiment will be described with reference to the accompanying drawings. A spinning machine 1 illustrated in FIG. 1 includes a plurality of spinning units 2 which are arranged in line. The spinning machine 1 includes a yarn splicing cart 3, a blower box 4 and a motor box 5. The yarn splicing cart 3 can travel in a direction in which the spinning units 2 are arranged.

[0020] As illustrated in FIG. 1, each of the spinning units 2 mainly includes a draft device 7, a pneumatic spinning device 9, a yarn feeding device 11 and a winding device 12. The draft device 7 is provided in an upper portion of a frame 6 of the spinning machine 1. The pneumatic spinning device 9 spins a fiber bundle 8 fed from the draft device 7 to produce spun yarn 10. The spun yarn 10 fed from the pneumatic spinning device 9 is fed by the yarn feeding device 11, and is thereafter wound by a winding device 12 to form a package 45. In FIG. 1, the winding device 12 is illustrated so as to form a cheese winding package, but may be structured so as to form a cone winding package. In the following description, "upstream" or "downstream" respectively means upstream or downstream in a feeding direction of the fiber bundle 8 (or the spun yarn 10).

[0021] The draft device 7 drafts a sliver 13 to form the fiber bundle 8. As illustrated in FIG. 2, the draft device 7 includes four rollers, which are a back roller 14, a third roller 15, a middle roller 17 provided with an apron belt 16, and a front roller 18.

[0022] A draft motor 31 made of an electric motor is installed at an appropriate position in the frame 6. The back roller 14 and the third roller 15 are connected to the draft motor 31 via a belt. Driving and stopping operations of the draft motor 31 are controlled by a unit controller provided in the spinning unit 2. In the spinning machine 1 according to the present embodiment, electric motors for driving the middle roller 17 and the front roller 18 are also provided in the frame 6, however, an illustration thereof is omitted.

[0023] The pneumatic spinning device 9 is structured by two divided blocks, that is, a first block 91 and a second block 92. The second block 92 is provided downstream of the first block 91.

[0024] The yarn feeding device 11 includes a delivery roller 39 which is supported by the frame 6 of the spinning machine 1, and a nip roller 40 which is arranged so as to make contact with the delivery roller 39. With this structure, the spun yarn 10 fed from the pneumatic spinning device 9 can be fed to the winding device 12 by nipping the spun yarn 10 between the delivery roller 39 and the nip roller 40 and rotating the delivery roller 39 by an electric motor (not illustrated).

[0025] The yarn splicing cart 3 includes a splicer (a yarn splicing device) 43, a suction pipe 44 and a suction mouth 46, as illustrated in FIGS. 1 and 2. As illustrated in FIG. 1, the yarn splicing cart 3 is provided so as to travel on a rail 41 provided on the frame 6 of the spinning machine 1 main body. If a yarn cut or a yarn breakage is generated in a certain spinning unit 2, the yarn splicing cart 3 travels to such a spinning unit 2 and stops. The suction pipe 44 sucks and catches a yarn end fed out from the pneumatic spinning device 9 and guides the yarn end to the splicer 43 while rotating in a vertical direction around an axis. The suction mouth 46 sucks and catches a yarn end from the package 45 rotatably supported by the winding device 12 and guides the yarn end to the splicer 43 while rotating in a vertical direction around an axis. The splicer 43 carries out yarn splicing of the guided yarn ends.

[0026] Next, a description will be made in detail on a structure of the pneumatic spinning device 9 with reference to FIG. 3. As illustrated in FIG. 3, the first block 91 includes a nozzle section casing 53, and a nozzle block 34 and a fiber guide section 23 that are held by the nozzle section casing 53. The second block 92 includes a hollow guide shaft body (a spindle) 20, and a shaft holding member 59.

[0027] A fiber guide hole 21 is formed in the fiber guide section 23. The fiber bundle 8 drafted by the draft device 7 is introduced to the fiber guide hole 21. The fiber guide section 23 holds a needle 22 which is arranged on a flow path of the fiber bundle 8 introduced from the fiber guide hole 21.

[0028] The nozzle block (a depressurized suction chamber section, a whirling chamber section) 34 is located downstream of the fiber guide section 23. FIG. 4 illustrates a detailed cross-sectional view of the nozzle block 34. FIG. 4 is a lateral cross-sectional view of the nozzle block 34 which is cut along the same plane as FIG. 3 (a plane passing through an axial line of the hollow guide shaft body 20). As illustrated in FIG. 4, a passage hole 70 is formed in the nozzle block 34. The passage hole 70 is formed such that a cross-sectional shape cut through a plane orthogonal to a central axis line 90 of the hollow guide shaft body 20 (a plane which is orthogonal to a fiber feeding direction) is circular.

[0029] As illustrated in FIG. 3, the hollow guide shaft body 20 includes a columnar body 56 held by a shaft holding member 59. A taper portion 24 is formed on one end of the columnar body 56. An inlet hole 28 is formed on a tip end of the taper portion 24. A fiber passage 29 continuing to the inlet hole 28 is formed in a shaft center portion of the columnar body 56. An outlet hole (not illustrated) is formed at a downstream end of the fiber passage 29. The fiber bundle 8 or the spun yarn 10 which has passed through the fiber passage 29 is fed from the outlet hole towards an outside of the pneumatic spinning device 9 by the yarn feeding device 11 arranged downstream of the pneumatic spinning device 9.

[0030] The taper portion 24 of the hollow guide shaft body 20 is inserted into the passage hole 70 formed in the nozzle block 34 from a side of the passage hole 70 located opposite to a fiber guide section 23 seen from the nozzle block 34, while bringing an axial line of the taper portion 24 in line with an inner portion of the passage hole 70. A predetermined space is formed between an outer peripheral surface of the taper portion 24 of the hollow guide shaft body 20 and an inner wall surface of the nozzle block 34 (a wall surface of the passage hole 70) such that airflow can pass therethrough.

[0031] A depressurized suction chamber 71, a whirling chamber 72 and a taper chamber 73 are formed in the nozzle block 34 in this order from upstream in a traveling direction of the fiber bundle 8. More precisely, the depressurized suction chamber 71 having a substantially cylindrical shape, the whirling chamber 72 having a substantially columnar shape and the taper chamber 73 having a substantially tapered cylindrical shape are formed by the outer peripheral surface of the taper portion 24 of the hollow guide shaft body 20 and the inner wall surface of the nozzle block 34 (the wall surface of the passage hole 70). Although the depressurized suction chamber 71 is formed substantially cylindrical, as illustrated in FIG. 3, a tip end of the hollow guide shaft body 20 (a tip end of the inlet hole 28 of the fiber passage 29) is actually slightly inserted from a downstream side of the depressurized suction chamber 71 into the depressurized suction chamber 71.

[0032] As illustrated in FIG. 3, the depressurized suction chamber 71 and the fiber guide hole 21 of the fiber guide section 23 are connected with one another. The whirling chamber 72 and the depressurized suction chamber 71 are connected with one another. The taper chamber 73 and the whirling chamber 72 are connected with one another.

[0033] A supply air accumulating chamber 61 is formed around the nozzle block 34. A compressed air supply pipe 65 connected to a pressurized air source (not illustrated) is connected to a nozzle section casing 53. Consequently, compressed air can be supplied from the pressurized air source to the supply air accumulating chamber 61.

[0034] At least one air injecting nozzle 27 connected to the whirling chamber 72 and the supply air accumulating chamber 61 is formed in the nozzle block 34. Although four air injecting nozzles 27 are formed in the present embodiment, the number of the air injecting nozzles 27 to be formed is not limited thereto. The air injecting nozzle 27 is structured as an elongated round hole formed through the nozzle block 34. The compressed air supplied to the supply air accumulating chamber 61 is injected into the whirling chamber 72 through the air injecting nozzle 27. Consequently, whirling airflow flowing to whirl in a single direction around an axial line of the hollow guide shaft body 20 is generated in the whirling chamber 72.

[0035] In order to generate such whirling airflow in the whirling chamber 72, a longitudinal direction of the air injecting nozzle 27 is directed substantially in a tangential direction of the whirling chamber 72 in plan view. FIG. 3 illustrates as if the longitudinal direction of the air injecting nozzle 27 exists in the same plane as the central axis line of the whirling chamber 72. However, FIG. 3 has been simply (conceptually) illustrated for facilitating understanding of the drawing. The air injecting nozzle 27 is actually formed in the tangential direction of the whirling chamber 72 as described above. Accordingly, a cross-sectional view illustrating the air injecting nozzle 27 more accurately is illustrated in FIG. 4.

[0036] As illustrated in FIGS. 3 and 4, the longitudinal direction of the air injecting nozzle 27 is slightly inclined towards the downstream side. Consequently, the compressed air injected from the air injecting nozzle 27 can flow towards the downstream.

[0037] With the above structure, the compressed air injected from the air injecting nozzle 27 flows towards the downstream in the traveling direction of the fiber bundle 8 while whirling in the whirling chamber 72. More specifically, spiral whirling airflow flowing towards the downstream can be generated in the whirling chamber 72.

[0038] An air discharge space 55 is formed in the nozzle section casing 53. The air discharge space 55 and the taper chamber 73 are connected with one another. A negative pressure source (suction unit) (not illustrated) arranged in the blower box 4 is connected to the air discharge space 55 through a pipe 60.

[0039] Next, a description will be made of a state when introducing the fiber bundle 8 to the fiber guide hole 21 in the pneumatic spinning device 9.

[0040] First, under a state in which the fiber bundle 8 is not introduced into the pneumatic spinning device 9 (a state illustrated in FIG. 3), the compressed air is supplied to the supply air accumulating chamber 61 from the compressed air source (not illustrated). The compressed air supplied to the supply air accumulating chamber 61 is injected towards the whirling chamber 72 via the air injecting nozzle 27. The whirling airflow generated accordingly in the whirling chamber 72 flows spirally downstream in the whirling chamber 72, and thereafter flows into the taper chamber 73. The whirling airflow further flows downstream while weakening its flow rate, and is finally discharged from the air discharge space 55.

[0041] Meanwhile, by the generation of the airflow towards the downstream in the whirling chamber 72, the depressurized suction chamber 71 which is adjacent to the upstream side of the whirling chamber 72 is depressurized, and the suction airflow is generated in the fiber guide hole 21. The suction airflow flows from the fiber guide hole 21 into the depressurized suction chamber 71. Thereafter, a portion of the suction airflow flows into the fiber passage 29 and flows downstream. The remaining suction airflow flows into the whirling chamber 72 and interflows with the whirling airflow.

[0042] If the fiber bundle 8 is fed from the draft device 7 to the pneumatic spinning device 9 under this state, the fiber bundle 8 is sucked from the fiber guide hole 21, and is guided into the depressurized suction chamber 71. The fiber bundle 8 guided into the depressurized suction chamber 71 is guided downstream through the fiber passage 29 along with the flow of the suction airflow that flows into the fiber passage 29, and is fed outside of the pneumatic spinning device 9 from the outlet hole (not illustrated) .

[0043] An end of the fiber bundle 8 or the spun yarn 10 which is fed out from the outlet hole of the pneumatic spinning device 9 is caught by the suction pipe 44 of the yarn splicing cart 3, and is spliced with the yarn end from the package 45 by the splicer 43. Accordingly, the fiber bundle 8 or the spun yarn 10 is continuous from the front roller 18, the fiber guide hole 21, the depressurized suction chamber 71 and the fiber passage 29 to the yarn feeding device 11. Under this state, when a feeding force towards the downstream is applied by the yarn feeding device 11, tension is applied to the spun yarn 10 and the spun yarn 10 is sequentially pulled out from the pneumatic spinning device 9.

[0044] Next, with reference to FIG. 5, a description will be made of a state in which twists are applied to the fiber bundle 8 to produce the spun yarn 10 in the pneumatic spinning device 9 according to the present embodiment. FIG. 5 conceptually illustrates the airflow within the pneumatic spinning device 9 by thick arrows.

[0045] The fiber bundle 8 is formed of a plurality of fibers. Each of the fibers is introduced into the depressurized suction chamber 71 from the fiber guide hole 21. A downstream end of each of the fibers is introduced into the fiber passage 29 along with the flow of the suction airflow flowing from the fiber guide hole 21 towards the fiber passage 29. Accordingly, at least a portion of the fibers introduced into the depressurized suction chamber 71 is continuous between the fiber guide hole 21 and the fiber passage 29. The fibers in this state will be referred to as core fibers 8a.

[0046] The core fibers 8a are twisted by being lead by reversal fibers 8b (described below) whirling in the whirling chamber 72. The twists tend to propagate upstream (towards the front roller 18), however, the propagation is prevented by the needle 22. Accordingly, the fiber bundle 8 fed from the front roller 18 is not twisted by the twist mentioned above. As described above, the needle 22 has a twist propagation preventing function.

[0047] A downstream end of each of the fibers introduced into the depressurized suction chamber 71 is twisted into the core fibers 8a which are being twisted. However, each of the fibers is not entirely twisted into the core fibers 8a and an upstream end is a free end.

[0048] When the free end (the upstream end) of each of the fibers enters into the depressurized suction chamber 71, the free end is separated from the core fibers 8a so as to be opened, and flows towards the whirling chamber 72 (the downstream) by the suction airflow flowing from the depressurized suction chamber 71 into the whirling chamber 72. As described above, the upstream end of the fiber flows towards the downstream, whereby the direction of the upstream end is "reversed". Short fiber in this state will be referred to as the reversal fiber 8b. The fiber which has been the core fiber 8a may become the reversal fiber 8b when its upstream end enters into the depressurized suction chamber 71.

[0049] The free end of the reversal fiber 8b is introduced into the whirling chamber 72, and is thus influenced by the whirling airflow flowing spirally towards the downstream. Accordingly, as illustrated in FIG. 5, the reversal fiber 8b whirls around the taper portion 24 of the hollow guide shaft body 20 while being along the surface of the taper portion 24 of the hollow guide shaft body 20. Therefore, the free end of the reversal fiber 8b is swung around the core fiber 8a passing through the fiber passage 29. Accordingly, the reversal fiber 8b is sequentially wound around the core fiber 8a so as to form the wound fiber.

[0050] At this time, the reversal fiber 8b is pushed against the surface of the taper portion 24 of the hollow guide shaft body 20 by a force of the whiling airflow that attempts to flow downstream. Accordingly, the free end of the reversal fiber 8b can be prevented from being disordered, and the reversal fiber 8b can whirl stably around the taper portion 24 of the hollow guide shaft body 20.

[0051] The core fiber 8a is fed downstream through the fiber passage 29. Accordingly, the reversal fiber 8b (the wound fiber) wound around the core fiber 8a is sequentially pulled into the fiber passage 29 together with the core fiber 8a. At this time, since the reversal fiber 8b is pushed against the surface of the taper portion 24 of the hollow guide shaft body 20 by the force of the whirling airflow that attempts to flow downstream, an appropriate tension is applied to the reversal fiber 8b when the reversal fiber 8b is pulled into the fiber passage 29. Consequently, the reversal fiber 8b is strongly wound around the core fiber 8a, and the spun yarn 10 having high strength can be produced.

[0052] Truly twisted spun yarn 10 is produced as described above. The spun yarn 10 advances through the fiber passage 29 and is fed out from the outlet hole (not illustrated) towards the yarn feeding device 11.

[0053] The spun yarn 10 is fed via the yarn feeding device 11 illustrated in FIG. 1 and is wound by the winding device 12, into a package 45. The fiber, which has been cut when being opened and twisted and which has not been twisted into the spun yarn 10, is fed from the whirling chamber 72 via the taper chamber 73 to the air discharge space 55 along with the flow of the airflow, and is discharged via the pipe 60 by the suction of the negative pressure source.

[0054] Next, a description will be made in detail of a structure of the nozzle block 34 in the pneumatic spinning device 9 according to the present embodiment.

[0055] First, description will be made of a shape of a whirling chamber forming surface 82 forming the whirling chamber 72.

[0056] As illustrated in FIG. 4, among an inner wall surface of the nozzle block 34 (a wall surface of the passage hole 70), a portion forming the depressurized suction chamber 71 is a depressurized suction chamber forming surface 81, and a portion forming the whirling chamber 72 is a whirling chamber forming surface 82. The depressurized suction chamber forming surface 81 is facing the depressurized suction chamber 71. The whirling chamber forming surface 82 is facing the whirling chamber 72.

[0057] FIG. 4 is a cross-sectional view illustrating the nozzle block 34 according to the present embodiment, which is cut along a plane passing through the central axis line of the hollow guide shaft body 20. In this cross-sectional view, a portion located upstream of the whirling chamber forming surface 82 (near the depressurized suction chamber 71) serves as a curved section 82a having a curved cross-sectional contour, and a portion located downstream of the whirling chamber forming surface 82 serves as a linear section 82b having a linear cross-sectional contour.

[0058] In the pneumatic spinning device 9 according to the present embodiment, a radius R1 of the depressurized suction chamber forming surface 81 is set to be smaller than a radius R2 of the whirling chamber forming surface 82 (accurately, a radius of the linear section 82b). In other words, a peripheral length of the whirling chamber 72 is greater than that of the depressurized suction chamber 71. By setting the radius of the depressurized suction chamber 71 to be smaller than that of the whirling chamber 72 as described above, the compressed air is prevented from flowing towards the depressurized suction chamber 71 even if the compressed air injected into the whirling chamber 72 expands. Consequently, the airflow can smoothly flow towards the downstream in the depressurized suction chamber 71, and the fiber can be smoothly reversed in the depressurized suction chamber 71.

[0059] As illustrated in FIG. 4, a downstream end of the depressurized suction chamber forming surface 81 and an upstream end of the linear section 82b of the whirling chamber forming surface 82 are connected to one another by the curved section 82a. In the cross-sectional view (FIG. 4) cut along the plane passing through the central axis line of the hollow guide shaft body 20, the cross-sectional contours of the curved section 82a and the linear section 82b are smoothly connected. By forming a cross-sectional contour of the upstream portion of the whirling chamber forming surface 82 (near the fiber guide section 23) in a curve, an angular portion is not formed in the whirling chamber 72.

[0060] On the other hand, for example, in Japanese Unexamined Patent Publication No. 2003-193337, the angular portion (the connecting portion of a first circular truncated cone shaped space section and a second circular truncated cone shaped space section) is formed in the whirling chamber (the first circular truncated cone shaped space section and the second circular truncated cone shaped space section). When the angular portion is formed in the whirling chamber as described above, a turbulence of airflow occurs in the whirling chamber, and a behavior of the reversal fiber may become unstable.

[0061] In the present embodiment, however, the angular portion is not provided in the whirling chamber 72 as described above. Therefore, the turbulence of the airflow can be reduced in the whirling chamber 72. Accordingly, the behavior of the reversal fiber in the whirling chamber 72 can be stabilized. As a result, the reversal fiber 8b can be prevented from floating up from the surface of the taper portion 24 of the hollow guide shaft body 20, and yarn of high quality can be stably produced.

[0062] In the present embodiment, more specifically, the cross-sectional contour of the curved section 82a has a shape of a circular arc. By forming the cross-sectional contour of the whirling chamber 72 as the circular arc, the turbulence of the airflow in the whirling chamber 72 can be reduced particularly well. By reducing the turbulence of the airflow in the whirling chamber 72, the compressed air injected into the whirling chamber 72 hardly expands in the whirling chamber 72.

[0063] When spinning speed is high, for example, 500 m/min or 600 m/min, it is particularly important to reliably whirl the reversal fiber to for a short period of time (at a high speed) with respect to the core fiber. However, when carrying out high-speed spinning, a period of time before the reversal fiber 8b is pulled into the fiber passage 29 is shortened. Therefore, the number of rotations of the reversal fiber 8b is greatly influenced by a slight turbulence of the airflow in the whirling chamber 72. By forming the cross-sectional contour of the curved section 82a of the whirling chamber 72 in the circular arc as in the present embodiment, the airflow in the whirling chamber 72 can be stabilized. Therefore, also in the case of high-speed spinning, the spinning yarn 10 of high quality can be stably produced.

[0064] Next, the air injecting nozzle 27 according to the present embodiment will be described.

[0065] As described above, the air injecting nozzle 27 is formed such that the longitudinal direction faces substantially tangential direction of the whirling chamber 72. Accordingly, an opening contour of a portion of the air injecting nozzle 27 opening into the whirling chamber forming surface 82 (a nozzle opening 27a) has a substantially oval shape as shown in FIG. 4. In the present embodiment, a peripheral length of the opening contour of the nozzle opening 27a is referred to as an oval peripheral length.

[0066] In the pneumatic spinning device 9 according to the present embodiment, the nozzle opening 27a of the air injecting nozzle 27 is formed on the curved section 82a of the whirling chamber forming surface 82 as shown in FIG. 4. Consequently, compared with the case in which the nozzle opening 27a is formed on the linear section 82b, for example, the oval peripheral length of the nozzle opening 27a can be increased. Accordingly, the air injecting nozzle 27 can inject compressed air such that the compressed air spreads towards the downstream. Thus, whirling airflow can act upon the fiber within a wide range. Therefore, the fiber can be whirled efficiently by a great force. Moreover, since the compressed air can be injected so as to spread towards the downstream, the compressed air hardly flows towards the upstream (the depressurized suction chamber 71 side) even if the compressed air expands in the whirling chamber 72. Accordingly, the whirling airflow can more smoothly flow towards the downstream, and the turbulence of the airflow in the whirling chamber 72 can be further reduced.

[0067] For example, in Japanese Unexamined Patent Publication No. 2003-193337, the nozzle opening of the air injecting hole is formed over the angular portion (the connecting portion of the cylindrical space portion and the first circular truncated cone shaped space section). For this reason, the opening shape of the nozzle opening is varied greatly just by a slight shift of the position where the nozzle opening is formed. Accordingly, the structure disclosed in Japanese Unexamined Patent Publication No. 2003-193337 has a drawback that quality of yarn is prone to be influenced by processing precision in the nozzle opening. However, in the present embodiment, the entire opening contour of the nozzle opening 27a is formed on the curved section 82a of the whirling chamber forming surface 82. More specifically, in the present embodiment, the nozzle opening 27a is formed at a position where the wall surface does not have the angular portion. According to the structure of the present embodiment, even if the position where the nozzle opening 27a is to be formed is shifted slightly, the shape of the opening contour of the nozzle opening 27a is not changed so much. As a result, the quality of the spun yarn 10 can be maintained regardless of the processing precision in the air injecting nozzle 27.

[0068] As shown in FIGS. 3 and 4, the tip end of the hollow guide shaft body 20 is slightly inserted into the depressurized suction chamber 71. In other words, the tip end of the hollow guide shaft body 20 is located upstream of a downstream end of the depressurized suction chamber forming surface 81. The nozzle opening 27a of the air injecting nozzle 27 is formed on the whirling chamber forming surface 82. More specifically, the nozzle opening 27a is formed further downstream than the tip end of the hollow guide shaft body 20. Consequently, the compressed air injected from the nozzle opening 27a can be prevented from colliding with the tip end of the hollow guide shaft body 20. Accordingly, the injected air can be prevented from expanding at the tip end of the hollow guide shaft body 20. Therefore, the whirling airflow can be favorably generated in the whirling chamber 72.

[0069] Next, an inclination angle of the air injecting nozzle 27 will be described. As described above, FIG. 4 is a cross-sectional view cut along the plane passing through the axial line of the hollow guide shaft body 20. The plane is parallel to a longitudinal direction of an air injecting nozzle 271 on a right side of FIG. 4. Accordingly, FIG. 4 is a view seen in a direction intersecting at right angle with the central axis line of the hollow guide shaft body 20 and intersecting at right angle with the longitudinal direction of the air injecting nozzle 271. In FIG. 4, an angle formed by a central axis line 90 of the hollow guide shaft body 20 and the longitudinal direction of the air injecting nozzle 271 is represented by an inclination angle α.

[0070] In the case in which the inclination angle α is small (the angle of the air injecting nozzle 27 is steep), the injected air flows swiftly towards the downstream. Although strong suction airflow can be generated in the fiber guide hole 21, whirling flow in the whirling chamber 72 is reduced. As a result, the reversal fiber 8b cannot be sufficiently wound around the core fiber 8a and the strength of the yarn may be decreased. Since the number of short fibers which are not twisted into the core fiber is increased, there may also arise a problem in that a fiber loss is increased. On the other hand, in the case in which the inclination angle α is large (the angle of the air injecting nozzle 27 is moderate), whirling airflow that whirls swiftly in the whirling chamber 72 can be generated by the injected air. However, flow towards the downstream is reduced. As a result, sufficient suction airflow cannot be generated in the fiber guide hole 21 and the fiber bundle 8 may not be sucked in some cases.

[0071] The present inventor has confirmed that a balance between the whirling airflow and the flow towards the downstream is excellent in the high-speed spinning if the inclination angle α is set to be at least 70° and be less than or equal to 80° in the pneumatic spinning device 9 according to the present embodiment. More specifically, by setting the inclination angle α within the above range, the suction of the fiber bundle 8 in the fiber guide hole 21 and the whirling of the reversal fiber 8b in the whirling chamber 72 can be appropriately carried out, thereby producing high quality spun yarn 10. Therefore, in the pneumatic spinning device 9 according to the present embodiment, the inclination angle α is set to be at least 70° and be less than or equal to 80°. Although the inclination angle α is illustrated for only the single air injecting nozzle 271 in the drawings, all of the plurality of air injecting nozzles 27 formed in the nozzle block 34 are formed at an equal inclination angle.

[0072] Next, a flow path area of the whirling chamber 72 will be described. The flow path area indicates a cross-sectional area of the whirling chamber 72 cut along a plane intersecting at right angle with a feeding direction of fiber.

[0073] In the present embodiment, the outer peripheral wall surface of the taper portion 24 of the hollow guide shaft body 20 which forms the inner peripheral wall of the whirling chamber 72 is formed in a tapered shape expanding towards the downstream side. Consequently, the flow path area of the whirling chamber 72 is reduced towards the downstream side from the position where the nozzle opening 27a is formed. Accordingly, a flow path area of a downstream end of the whirling chamber 72 is smaller than that of the position where the nozzle opening 27a is formed.

[0074] Since the flow path area of the whirling chamber 72 is slightly reduced at the downstream side, the air injected from the nozzle opening 27a can be prevented from flowing towards the taper chamber 73 without sufficiently whirling in the whirling chamber 72. Consequently, a flow rate of the whirling airflow can be maintained high until the whirling airflow is discharged from the whirling chamber 72 to the taper chamber 73.

[0075] As described above, the pneumatic spinning device 9 according to the present embodiment causes the fibers of the fiber bundle 8 to whirl by the whirling airflow, thereby producing the spun yarn 10, and includes the nozzle block 34 and the hollow guide shaft body 20. The nozzle block 34 has the depressurized suction chamber 71 and the whirling chamber 72 formed therein. The peripheral length of the whirling chamber 72 is greater than that of the depressurized suction chamber 71. At least one air injecting nozzle 27 is formed in the nozzle block 34. The air injecting nozzle 27 injects the compressed air from the nozzle opening 27a opening into the whirling chamber 72 to generate the whirling airflow in the whirling chamber 72. The fiber passage 29 is formed in the hollow guide shaft body 20. The tip end of the hollow guide shaft body 20 located at the inlet hole 28 side of the fiber passage 29 is arranged to be located within the depressurized suction chamber 71. The nozzle opening 27a is set downstream than the tip end of the hollow guide shaft body 20 in the feeding direction of fiber bundle 8.

[0076] As described above, since the nozzle opening 27a is formed close to the whirling chamber 72 and the tip end of the hollow guide shaft body 20 is located within the depressurized suction chamber 71, the compressed air injected from the nozzle opening 27a can be prevented from expanding in proximity of the tip end of the hollow guide shaft body 20. As a result, the reversal fiber 8b can be prevented from floating up at the tip end of the hollow guide shaft body 20. More specifically, the reversal fiber 8b can be stably pushed against the tip end of the hollow guide shaft body 20 by the compressed air. Moreover, by forming the peripheral length of the depressurized suction chamber 71 to be shorter than that of the whirling chamber 72, the expanded compressed air hardly flows from the whirling chamber 72 towards the depressurized suction chamber 71. Consequently, the whirling component of the whirling airflow in the depressurized suction chamber 71 is reduced and the airflow flowing gently towards the downstream occupies the depressurized suction chamber 71. Accordingly, the fiber is smoothly reversed in the whirling chamber 72, and appropriate tension can be stably applied to the fiber wound around the core fiber 8a. As a result, the strength of the produced spun yarn 10 can be enhanced. Moreover, the reversal fiber 8b hardly float up from the surface of the hollow guide shaft body 20, and stable spinning can be carried out even if the whirling speed of the fiber is increased. Accordingly, high-speed spinning of 500 m/min or 600 m/min can be carried out which could not be conventionally implemented.

[0077] In the pneumatic spinning device 9 according to the present embodiment, in the cross-section cut along the plane passing through the axial line of the hollow guide shaft body 20, the portion close to the depressurized suction chamber 71 in the whirling chamber forming surface 82 is formed as the curved section 82a having the cross-sectional contour which is substantially curved. Consequently, the whirling chamber 72 can be formed such that the angular portion is not formed on the wall surface near the depressurized suction chamber 71. Accordingly, the airflow can be prevented from being disturbed in the whirling chamber 72, and the airflow can flow smoothly. Thus, the winding fiber can be prevented from being irregularly wound around the core fiber or the free ends of the winding fiber can be prevented from being entangled with one another. As a result, the quality of the spun yarn 10 to be produced can be stabilized.

[0078] In the pneumatic spinning device 9 according to the present embodiment, the entire opening contour of the nozzle opening 27a is formed on the curved section 82a of the whirling chamber forming surface 82. By forming the nozzle opening 27a on the curved section 82a, the oval peripheral length of the opening contour of the nozzle opening 27a can be increased. Consequently, the compressed air can be injected from the nozzle opening 27a so as to spread into the whirling chamber 72. Thus, the whirling airflow can be applied to the fiber within a wider range. As a result, the fiber can be efficiently whirled by a great force. By forming the nozzle opening 27a on the curved section 82a as described above, the shape of the outlet of the air injecting nozzle 27 is not greatly changed even if the position where the nozzle opening 27a is formed is slightly shifted. In other words, by forming the pneumatic spinning device 9 as described above, the quality of the produced spun yarn 10 can be maintained regardless of the processing precision in the air injecting nozzle 27.

[0079] In the pneumatic spinning device 9 according to the present embodiment, when viewed in the direction intersecting at right angle with the central axis line of the hollow guide shaft body 20 and intersecting at right angle with the longitudinal direction of the air injecting nozzle 27, the longitudinal direction of the air injecting nozzle 27 is inclined at the angle which is at least 70 degrees and is less than or equal to 80 degrees with respect to the central axis line of the hollow guide shaft body 20. Consequently, the balance between the speed in the whirling direction and the speed in the fiber feeding direction in the whirling airflow acting on the fiber in the whirling chamber 72 is particularly preferable in the high-speed spinning. More specifically, the fiber can be whirled at sufficient speed while suction flow is generated for pulling the fiber towards the downstream in the fiber feeding direction by the compressed air injected from the air injecting nozzle 27 formed as described above. As a result, the strength of the spun yarn 10 to be produced can be enhanced. Furthermore, since the whirling component of the air acting on the fiber is maintained in the whirling chamber 72, floating short fibers can be sequentially caught and wound around the reversal fiber and a fiber loss can be reduced.

[0080] The pneumatic spinning device 9 according to the present embodiment is formed such that a flow path cross-sectional area of the downstream end of the whirling chamber 72 is smaller than a flow path cross-sectional area at the position where the nozzle opening 27a is formed in the whirling chamber 72. Consequently, the whirling airflow can be maintained at high speed until the whirling airflow is discharged from the whirling chamber 72. More specifically, the fiber can be whirled at high speed in the whirling chamber 72, and the strength of the spun yarn 10 to be produced can be enhanced also in the case of high-speed spinning.

[0081] The spinning machine 1 according to the present embodiment includes the pneumatic spinning device 9, and the winding device 12 for winding the spun yarn 10 produced by the pneumatic spinning device 9 into the package 45. Therefore, also in the high-speed spinning, the spun yarn 10 having the enhanced strength can be produced. Accordingly, the package 45 of high quality can be more efficiently formed at a higher speed than in the conventional spinning machine.

[0082] Next, a second embodiment according to the present invention will be described. In the following description, identical or similar structures to those in the first embodiment are denoted with the same reference numerals as those in the first embodiment and description thereof will be omitted.

[0083] FIG. 6 illustrates a structure of a pneumatic spinning device 9 provided in a spinning machine according to the second embodiment. As illustrated in FIG. 6, the pneumatic spinning device 9 according to the present embodiment has a structure in which the needle 22 provided in the fiber guide section 23 in the first embodiment is omitted. That is, the needle 22 may be omitted. In the first embodiment, the needle 22 serves as a twist propagation preventing function. If the needle 22 is omitted as in the second embodiment, a downstream end of the fiber guide section 23 serves as the twist propagation preventing function.

[0084] Although the preferred embodiments according to the present invention have been described above, the structures can be changed as follows, for example.

[0085] Although the whirling chamber 72 is substantially cylindrical in the above embodiments, the present invention is not limited thereto. For example, as in the prior art disclosed in Japanese Unexamined Patent Publication No. 2003-193337, the outer peripheral wall of the whirling chamber (the first circular truncated cone shaped space section and the second circular truncated cone shaped space section) may be formed to be substantially tapered. However, since the whirling chamber 72 is required to generate whirling airflow therein, the cross-sectional shape of the whirling chamber 72 cut along the plane intersecting at right angle with the fiber feeding direction is preferably circular.

[0086] Although the depressurized suction chamber 71 is formed substantially cylindrical, the present invention is not limited thereto. Since the whirling airflow is not required to be generated in the depressurized suction chamber 71, the cross-sectional shape of the depressurized suction chamber 71 cut along the plane intersecting at right angle with the fiber feeding direction may not be circular. However, also in this case, the outer peripheral length of the depressurized suction chamber 71 is preferably set to be smaller than that of the whirling chamber 72 to prevent the airflow from flowing from the whirling chamber 72 into the depressurized suction chamber 71.

[0087] In the curved section 82a of the whirling chamber forming surface 82, the cross-sectional contour along the plane passing through the axial line of the hollow guide shaft body 20 may not be a circular arc shape but may be any shape as long as the cross-sectional contour is a smooth curve. In short, it is sufficient if the angular portion does not exist on the fiber guide section 23 side of the whirling chamber 72. However, the turbulence of the airflow in the whirling chamber 72 can be suppressed particularly well by forming the cross-sectional contour of the curved section 82a as the circular arc as described above.

[0088] The entire cross-sectional contour of the whirling chamber forming surface 82 may be formed in a curved shape. In other words, the linear section 82b may be omitted.

[0089] If the cross-sectional contour of the curved section 82a may be regarded to be substantially a curve, the cross-sectional contour may be formed by fine broken lines. For example, if the cross-sectional contour of the curved section 82a is formed by a fine broken line bent a plurality of times at an obtuse angles, the cross-sectional contour may be regarded to be substantially a curve.

[0090] The curved section 82a is not required to be formed on the whirling chamber forming surface 82 as in the above embodiments. That is, an angular portion may be formed in the whirling chamber 72. For example, the curved section 82a may be omitted, and the whirling chamber forming surface 82 may be formed only by the linear section 82b.

[0091] Although the entire opening contour of the nozzle opening 27a of the air injecting nozzle 27 is formed in the curved section 82a in the above embodiments, the present invention is not limited to this structure. For example, only a portion of the opening contour of the nozzle opening 27a may be formed in the curved section 82a and a remaining portion thereof may be formed in the linear section 82b. Moreover, the entire opening contour of the nozzle opening 27a may be formed in the linear section 82b. However, as described above, if at least a portion of the opening contour of the nozzle opening 27a is formed in the curved section 82a, compressed air can be injected while spreading from the nozzle opening 27a into the whirling chamber 72, and this structure is preferable.

[0092] Although the nozzle block 34 serves as the depressurized suction chamber section and the whirling chamber section in the above embodiments, the depressurized suction chamber section and the whirling chamber section may be provided as separate members.

[0093] In the above embodiments, the air discharge space 55 is formed in the nozzle section casing 53. However, the air discharge space 55 may be formed in the shaft holding member 59. The air discharge space 55 may be formed by combining the nozzle section casing 53 and the shaft holding member 59.

[0094] Although the description has been made on the spinning machine 1 in which the fiber bundle 8 (or the spun yarn 10) is fed from top towards bottom in the present embodiment, the present invention is not limited thereto. For example, a spinning machine can be employed in which the fiber bundle 8 is fed from bottom to top. More specifically, the pneumatic spinning device according to the present embodiment may be provided in a spinning machine in which a can accommodating the fiber bundle is arranged in a lower part of a machine main body and a winding device is arranged in an upper part of the machine main body.

[0095] The spinning machine 1 may be structured such that a yarn accumulating device is provided between the yarn feeding device 11 and the winding device 12. The yarn accumulating device will be briefly described. The yarn accumulating device is structured such that the spun yarn 10 is temporarily wound around a rotating yarn accumulating roller so that a prescribed amount of the spun yarn 10 can be accumulated on the yarn accumulating roller. The yarn accumulating device has the following function. That is, the winding device 12 cannot wind the spun yarn 10 during a yarn splicing operation by the yarn splicing cart 3. In this case, if the spun yarn 10 is continuously fed from the pneumatic spinning device 9, the spun yarn 10 which is not wound slackens. Therefore, the spun yarn 10 can be prevented from slackening by providing the yarn accumulating device between the winding device 12 and the yarn feeding device 11, and accumulating the spun yarn 10 on the yarn accumulating roller during a period in which the winding device 12 cannot wind the yarn. Consequently, the spun yarn 10 can be prevented from slackening.

[0096] The above yarn accumulating device includes the yarn accumulating roller which rotates while winding the spun yarn 10. The above yarn accumulating device can feed the spun yarn 10 wound around the yarn accumulating roller towards the downstream by rotating the yarn accumulating roller. In other words, the yarn accumulating device has a function of feeding the spun yarn 10 towards the downstream. Accordingly, the spinning machine 1 including the yarn accumulating device as described above may be structured such that the yarn feeding device 11 is omitted and the spun yarn 10 is delivered from the pneumatic spinning device 9 towards the downstream by the yarn accumulating device.

Claims

1. A pneumatic spinning device (9) for producing spun yarn by whirling fiber of a fiber bundle by whirling airflow, comprising:

a depressurized suction chamber section (34) in which a depressurized suction chamber (71) is formed,

a whirling chamber section (34) in which a whirling chamber (72) is formed, a peripheral length of the whirling chamber (72) being longer than a peripheral length of the depressurized suction chamber (71), and in which at least one air injecting nozzle (27) is formed to inject compressed air from a nozzle opening (27a) opening into the whirling chamber (72) to generate the whirling airflow in the whirling chamber (72); and

a spindle (20) in which a fiber passage (29) is formed;

wherein the spindle (20) is arranged such that a tip end at an inlet of the fiber passage (29) is located within the depressurized suction chamber (71), and

the nozzle opening (27a) is located downstream than the tip end of the spindle (20) in a feeding direction of the fiber bundle.

2. The pneumatic spinning device (9) according to claim 1, wherein in a cross-section cut through a plane passing through an axial line of the spindle (20), at least a portion (82a) of a cross-sectional contour of an inner wall surface (82) of the whirling chamber section (34) forming the whirling chamber (72) located near the depressurized suction chamber (71) is formed substantially in a curve.

3. The pneumatic spinning device (9) according to claim 2, wherein at least a portion of an opening contour of the nozzle opening (27a) is formed on the circular cross-sectional contour portion (82a) among the inner wall surface (82) of the nozzle block (34) forming the whirling chamber (72).

4. The pneumatic spinning device (9) according to any one of claim 1 through claim 3, wherein when viewed from a direction intersecting with a central axis line of the spindle (20) and intersecting with a longitudinal direction of the air injecting nozzle (27), the longitudinal direction of the air injecting nozzle (27) is inclined by an angle that is at least 70 degrees and less than or equal to 80 degrees with respect to the central axis line of the spindle (20).

5. The pneumatic spinning device (9) according to any one of claim 1 through claim 4, wherein a flow path cross-sectional area of a downstream end of the whirling chamber (72) is formed smaller than a flow path cross-sectional area of a portion in the whirling chamber (72) where the nozzle opening (27a) is formed.

6. A spinning machine comprising:

the pneumatic spinning device (9) according to any one of claim 1 through claim 5; and

a winding device (12) adapted to wind spun yarn produced by the pneumatic spinning device (9) into a package.

Drawing