The present invention relates to a spinning device comprising a hollow guide shaft having a yarn path formed therein through which a spun yarn is guided, a first air nozzle that generates a whirling air current in a space at an inlet of the yarn path, and a second air nozzle that generates an air current in the middle of the yarn path, as well as a spinning method using the spinning device.

A known pneumatic spinning device carries out spinning by exposing a fiber bundle to a whirling air current.

The spinning device comprises a hollow guide shaft having a yarn path formed therein and an air nozzle that generates a whirling air current in a space at an inlet of the yarn path. A fiber bundle is fed out toward the yarn path, and the air nozzle is driven (to inject air), and a whirling air current is generated by the air nozzle to separate outer fibers (winding fibers) of the fiber bundle from some fibers left in the center of the bundle (core fibers). The winding fibers then whirl outside the hollow guide shaft and wind around the core fibers to generate a fasciated spun yarn.

An example of these spinning devices is disclosed in the Unexamined Japanese Patent Application Publication (Tokkai) No. 2003-155630 .

The spinning device disclosed in the Unexamined Japanese Patent Application Publication (Tokkai) No. 2003-155630 has an auxiliary nozzle placed in the yarn path in addition to the main air nozzle that generates a fasciated spun yarn. The auxiliary nozzle is an air nozzle that enhances a yarn discharging performance when a fiber bundle is newly passed through the spinning device (discharge the yarn) after yarn cutting for yarn splicing or the like. The auxiliary nozzle generates a whirling air current in the yarn path in a direction opposite to that of an air current generated by the main nozzle to enable the initial yarn discharging.

In the pneumatic spinning, a whirling air current generated by the air nozzle separates outer fibers (winding fibers) of the fiber bundle from some fibers left in the center of the bundle(core fibers). However, the separated fibers may be discharged from the spinning device without winding around the core fibers. That is, part of the fiber bundle, the material of spun yarns, becomes a fiber loss.

A cause of the fiber loss is that the whirling air current forms an air current flowing backward from the inside to the inlet of the yarn path. Thus, the fibers in a fiber bundle supplied by a draft section are not caught in a spun yarn being generated. That is, the backward flowing air current may hinder the spinning.

That is, an object of the present invention is to reduce a fiber loss that may occur during spinning carried out by a pneumatic spinning device.

A description has been given of the problems to be solved by the present invention. Now, the description will be given of means for solving the problems.

According to Claim 1, there is provided a spinning device comprising:

• a hollow guide shaft having a yarn path formed in an axial position and through which a spun yarn is fed out;
• a first air nozzle that generates a whirling air current to which a fiber bundle is exposed, in a space at an inlet of the yarn path; and
• a second air nozzle that generates an air current having a yarn feed-out direction component acting along the yarn path, in the middle of the yarn path.

This configuration has the following advantage.

The whirling air current generated by the first air nozzle separates the outer fibers of the fiber bundle, and the outer fibers wind around the core fibers in the center of the fiber bundle to generate a spun yarn.

Then, an axial air current generated by the second air nozzle sucks air from the inlet to the inside of the yarn path. This allows the separated outer fibers to be readily drawn into the yarn path.

In the spinning device according to Claim 2, the air current generated by the second air nozzle is a whirling air current having not only the yarn feed-out direction component but also a whirling direction component acting around the yarn feed-out direction , and

a whirling direction of the whirling air current from the first air nozzle is set the same as a whirling direction of the whirling air current from the second air nozzle.

This arrangement has the following advantage.

The first air nozzle and second air nozzle generate a whirling air current in the same whirling direction. This allows the spun yarn to be additionally twisted.

According to Claim 3, there is provided a spinning method using a spinning device according to Claim 1 or Claim 2, wherein spinning is carried out by continuously injecting air both from the first air nozzle and from the second air nozzle.

This configuration allows an operation similar to that in Claim 1 or Claim 2 to continue during spinning.

The present invention exerts the following effects.

According to Claim 1, the outer fibers separated by the whirling air current generated by the first air nozzle are readily drawn into the yarn path. This reduces a possible fiber loss.

According to Claim 2, the spun yarn is additionally twisted to increase its strength.

According to Claim 3, an effect similar to that of Claim I or Claim 2 can be continuously produced during spinning.

Other features, elements, processes, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.

• Figure 1 is a perspective view showing the configuration of a pneumatic spinning machine.
• Figure 2 is a vertical sectional view of a spinning device.
• Figure 3 is a horizontal sectional view of periphery of a first air nozzle in the spinning device.
• Figure 4 is a horizontal sectional view of periphery of a yarn discharging air nozzle in the spinning device.
• Figure 5 is a horizontal sectional view of periphery of a second air nozzle in the spinning device.

An embodiment of the present invention will be described with reference to the drawings.

A spinning machine 3 will be described with reference to Figure 1.

The spinning machine 3 is an apparatus that blows a whirling air current against a fiber bundle (sliver) 6 to manufacture a spun yarn 9.

The spinning machine 3 has a can 5 which is placed at the most upstream position, a draft device 7, a spinning device 10, a yarn feeding device 20, a yarn defect detecting device 30, and a winding device 40 which are sequentially arranged along a path (hereinafter referred to as a yarn feeding path) along which the spun yarn 9 is manufactured from the fiber bundle 6.

The can (sliver container) 5 accommodates the fiber bundle 6 generated by a drawing frame.

In Figure 1, the spinning machine 3 is one unit of apparatus that manufactures a spun yarn 9. However, a plurality of the apparatuses arranged in a line, each of which manufactures a spu yarn, may be called a spinning machine as a whole.

The draft device 7 comprises four pairs of draft rollers that draft the fiber bundle between the rollers. The four pairs of draft rollers include a back roller pair 71, a third roller pair 72, a second roller pair 73, and a front roller pair 74 which are arranged along the direction in which the fiber bundle 6 is conveyed.

The spinning device 10 manufactures a spun yarn (fasciated spun yarn) 9 by allowing a whirling air current to act on the fiber bundle 6.

The spinning machine 3 in accordance with the present embodiment has a spinning speed of 300 to 400 m/min, which is about 20 times as high as that of a ring spinning machine (20 to 30 m/min); the spinning machine 3 is able to achieve high-speed spinning.

The yarn feeding device 20 feeds the spun yarn 9 manufactured by the spinning device 10 out to the winding device 40. The yarn feeding device 20 comprises a delivery roller 21 and a nip roller 22 which nip and feed out the spun yarn 9.

The yarn defect detecting device 30 detects a yarn defect in the spun yarn 9 being fed to the winding device 40. On the basis of yarn defect detection information from the yarn defect detecting device 30, the yarn defect portion is removed to prevent an improper yarn from being wound into a package 4. The yarn defect detecting device 30 comprises a cutting device (not shown in the drawings) that cuts the spun yarn 9 in response to the detection of a yarn defect.

To cut away yarn defect portion, the spinning machine 3 also comprises yarn splicing means (not shown in the drawings) for splicing both ends of the cut spun yarn 9 together.

The winding device 40 transversally winds the spun yarn 9 manufactured by the spinning device 10 in an axial direction of a bobbin to form a package 4.

The configuration of the spinning device 10 will be described with reference to Figure 2.

The spinning device 10 has a needle block 11, a nozzle block 12, and a hollow guide shaft 13 arranged along a yarn feed-out direction (the direction in which the fiber bundle 6 and spun yarn 9 are fed out) A. The yarn feed-out direction A corresponds to a direction from the top to bottom of Figure 2.

The spinning device 10 internally has a fiber introducing path 11a, an i nvers i on chamber 14, a whirling air current generating chamber 15, and a yarn path 13b through all of which the fiber bundle 6 or spun yarn 9 pass or move. The fiber introducing path 11a, whirling air current generating chamber 15, and yarn path 13b are independent of one another but are in communication with one another via the inversion chamber 14.

The spinning device 10 also comprises a first air nozzle 16 which injects air into the inversion chamber 14, and an auxiliary nozzle 19 and a second air nozzle 17 which inject air into the yarn path 13b.

In summary, first, the fiber bundle 6 is introduced into the inversion chamber 14 via the fiber introducing path 11a. The fiber bundle 6 introduced in the inversion chamber 14 is unbundled and then twisted by a whirling air current B1 generated in the whirling air current generating chamber 15 by air injected by the first air nozzle 16. This results in a spun yarn 9 at the tip of a needle 18 in the inversion chamber 14. The spun yarn 9 is fed out of the spinning device 10 via the yarn path 13b.

The needle block 11 is a member that supports the needle 18 which guides the fibers in the inversion chamber 14. The needle 18 advances into the inversion chamber 14 and projects toward the yarn path 13b. The position at which the needle 18 is fixed is adjustable, and the amount of projection of the needle 18 toward the yarn path 13b can be changed.

The needle block 11 has the fiber introducing path 11a formed therein.

The hollow guide shaft 13 is a member constituting a path (yarn path 13b) through which the spun yarn 9 is passed, and the hollow guide shaft 13 also guides whirling movement of whirling fibers (winding fibers 6a described below) separated from the fiber bundle 6 by the whirling air current B1.

The hollow guide shaft 13 is cylindrical and has an inner wall surface forming the yarn path 13b and an outer wall surface forming a guide surface for the winding fibers 6a. The axial direction of the hollow guide shaft 13 aligns with the yarn feed-out direction A, and the hollow guide shaft 13 is symmetric with respect to its axis, and the yarn path 13b is located at the axial position.

The inversion chamber 14 is a columnar space, and wall surfaces of two opposite members, the needle block 11 and hollow guide shaft 13, correspond to the opposite bottom surfaces of the columnar space, and an inner wall surface of the nozzle block 12 corresponds to a side surface of the columnar space. An inlet of the yarn path 13b is open into the inversion chamber 14. Accordingly, the inversion chamber 14 constitutes an inlet side space of the yarn path 13b.

The whirling air current generating chamber 15 is a space shaped like a truncated cone and a cylinder. The outer wall surface of the hollow guide shaft 13 corresponds to an inner surface of the cylinder. The inner wall surface of the nozzle block 12 corresponds to an outer wall surface of the cylinder.

The first air nozzle 16, shown in Figures 2 and 3, will be described below.

The spinning device 10 comprises the first air nozzle 16 as means for generating a whirling air current B1 in the inversion chamber 14 (the space at an inlet of the yarn path 13b) and whirling air current generating chamber 15. In the present embodiment, the first air nozzle 16 forms a part of the nozzle block 12 and is composed of first nozzle holes 12a, 12a, ... formed in the nozzle block 12 and peripheries of the first nozzle holes 12a, 12a, .... Each of the first nozzle holes 12a is in communication with the whirling air current generating chamber 15.

Air is fed through the first nozzle holes 12a, 12a, ... by air supply means (not shown in the drawings) and ejected into the inversion chamber 14.

As shown in Figure 3, each of the first nozzle holes 12a is formed to communicate with the inside of the whirling air current generating chamber 15 from a tangential direction of the whirling air current generating chamber 15, which is a cylindrical space. Thus, air ejected from the first nozzle holes 12a generates a whirling air current B1 in the inversion chamber 14 and whirling air current generating chamber 15 (particularly the whirling air current generating chamber 15). In particular, the plurality of the first nozzle holes 12a, 12a, ... are spaced at equal intervals in a circumferential direction of the whirling current generating chamber 15, which is a cylindrical space. Further, air is uniformly injected through all of the first nozzle holes 12a, 12a, ... Thus, a whirling air current B1 that is uniform in the circumferential direction (around the axis extending in the yarn feed-out direction A) is generated in the inversion chamber 14 and the whirling air current generating chamber 15.

With the first nozzle holes 12a, 12a, ... configured as shown in Figure 3, the whirling air current B1 generated in the inversion chamber 14 and the whirling air current generating chamber 15 whirls counterclockwise around the axis extending in the yarn feed-out direction A.

Each of the first nozzle holes 12a is formed generally perpendicularly to the yarn feed-out direction A, and more specifically, the first nozzle holes 12a are inclined toward the yarn feed-out direction A side. Thus, the flow of air ejected from the first nozzle holes 12a is provided not only with the whirling component acting around the axis extending in the yarn feed-out direction A but also with a component acting toward the yarn feed-out direction A.

The whirling air current B1 generated by the first air nozzle 16 is thus provided with the component acting toward the yarn feed-out direction A. This allows the external air to be sucked through the fiber introducing path 11a, allowing the fiber bundle 6 to be easily introduced into the inversion chamber 14.

Spinning is carried out as follows.

The fiber bundle 6 is introduced into the inversion chamber 14. The whirling air current B1 generated in the inversion chamber 14 and the whirling air current generating chamber 15 separates outer fibers (hereinafter referred to as winding fibers 6a) from the introduced fiber bundle 6, with some fibers (hereinafter referred to as core fibers) left in the center of the bundle. The whirling air current B1 generated in the inversion chamber 14 and the whirling air current generating chamber 15 flows in the yarn feed-out direction A. The winding fibers 6a whirl while being drawn into the whirling air current generating chamber 15, and wind around the core fibers. The winding fibers 6a are entangled with the core fibers to generate a fasciated spun yarn 9.

Now, the auxiliary nozzle 19, shown in Figures 2 and 4, will be described.

The auxiliary nozzle 19 is means for enabling the spinning device 10 to first discharge a spun yarn (newly introducing the fiber bundle 6 into the spinning device 10 to start generating a spun yarn 9).

Once spinning is started to get the spinning device 10 ready to deliver the spun yarn 9, the fiber bundle 6 can be sequentially formed into a spun yarn 9 simply by actuating the first air nozzle 16.

At time of yarn discharging, the auxiliary nozzle 19 generates a negative pressure that allows the fiber bundle 6 to be introduced into the yarn path 13b and a whirling air current B3 that flows in a direction opposite to that of the whirling air current B1 generated by the first air nozzle 16. Then, when the core fibers 6 already twisted by the auxiliary nozzle 19 are untwisted downstream side of the auxiliary nozzle 19, the direction in which the core fibers are untwisted is the same as that in which winding fibers 6a wound around the core fibers have been twisted. This allows the winding fibers 6a to wind firmly around the core fibers to generate a kind of yarn before generating a spun yarn 9.

The auxiliary nozzle 19 generates an air current (whirling air current B3) in the yarn path 13b, and the air current has the component (1) acting in the yarn feed-out direction A and the component (2) acting around the axis extending in the yarn feed-out direction A.

The component (1) acting in the yarn feed-out direction A makes the air pressure in the yarn path 13b negative with respect to the air pressure in the inversion chamber 14. The component (2) acting around the axis extending in the yarn feed-out direction A twists the core fibers in the direction opposite to that in which the winding fibers 6a whirl.

As shown in Figure 2, in accordance with the present embodiment, the auxiliary nozzle 19 forms a part of the hollow guide shaft 13, and is composed of yarn discharging nozzle holes 13c, 13c, ... and the peripheries of the yarn discharging nozzle holes 13c, 13c, ... The yarn discharging nozzle holes 13c are in communication with the inside of the yarn path 13b in the middle of the yarn path 13b.

Air is fed through the yarn discharging nozzle holes 13c, 13c, ... by air supply means (not shown in the drawings) and ejected into the yarn path 13b.

The auxiliary nozzle 19 is different from the first air nozzle 16 in the place to which air is ejected and in the place in which a whirling air current is generated.

On the other hand, the auxiliary nozzle 19 is the same as the first air nozzle 16 in the following points: the nozzle holes are arranged around the axis of the yarn feed-out direction A at equal intervals, the direction in which air is ejected from the nozzle holes is the same as that in which a whirling air current is generated, and the whirling air current is provided with the component acting in the yarn feed-out direction A. However, the whirling direction of the whirling air current B3, generated by the auxiliary nozzle 19, is opposite to that of the whirling air current B1 generated by the first air nozzle 16.

Each of the yarn discharging nozzle holes 13c is formed generally perpendicularly to the yarn feed-out direction A, and more specifically, the yarn discharging nozzle holes 13c are inclined toward the yarn feed-out direction A side. The yarn discharging nozzle holes 13c correspond to areas that are immediately adjacent to and in communication with the yarn path 13b (the peripheries of the openings in communication with the yarn path 13b). The direction in which the yarn discharging nozzle holes 13c are formed allows the flow of air ejected from the yarn discharging nozzle holes 13c to be provided with the component acting toward the yarn feed-out direction A.

As shown in Figure 4, each of the yarn discharging nozzle holes 13c is formed to communicate with the inside of the yarn path 13b, which is a cylindrical space, from a tangential direction of the yarn path 13b. Thus, air ejected from each of the yarn discharging nozzle holes 13c generates a whirling air current B3 in the yarn path 13b. The whirling air current B3 has not only the component acting in the yarn feed-out direction A but also the component acting around the axis extending in the yarn feed-out direction A. However, the whirling air current B3 flows in the direction opposite to that in which the whirling air current B1 flows.

In particular, the plurality of yarn discharging nozzle holes 13c. 13c, ... are spaced at equal intervals in the circumferential direction of the yarn path 13b, which i$ a cylindrical space, and further, air is uniformly injected through all of the yarn discharging nozzle holes 13c, 13c, ... Thus, a whirling air current B3 that is uniform in the circumferential direction (around the axis extending in the yarn feed-out direction A) is generated in the yarn path 13b.

The yarn discharging nozzle holes 13c, 13c, ... configured as shown in Figure 4 generate a clockwise whirling air current B3 in the yarn path 13b.

Now, the second nozzle hole 17, shown in Figures 2 and 5, will be described.

The second air nozzle 17 is means for allowing the spun yarn 9 to be more efficiently generated. Specifically, the second air nozzle 17 generates an air current (whirling air current B2) in the yarn path 13b; the air current has the component (1) acting in the yarn feed-out direction A and the component (2) acting around the axis extending in the yarn feed-out direction A.

The component (1) acting in the yarn feed-out direction A makes the air pressure in the yarn path 13b negative with respect to the air pressure in the inversion chamber 14. The component (2) acting around the axis extending in the yarn feed-out direction A additionally twists the spun yarn 9.

First, the air pressure in the yarn path 13b is set negative with respect to the air pressure in the inversion chamber 14 because the air injected by the first air nozzle 16 makes the air pressure in the yarn path 13b positive with respect to the air pressure in the inversion chamber 14 (the air flows from the yarn path 13b to the inversion chamber 14). This is because the high pressure of air ejected from the whirling air current generating chamber 15 side to the outside causes air to be sucked from the center toward outer periphery of the inversion chamber 14. As a result, some of the winding fibers 6a are discharged from the whirling air current generating chamber 15 side directly to the outside without being entangled with the core fibers. This unfortunately leads to a fiber loss.

Second, the spun yarn 9 is additionally twisted in order to enhance the entanglement of the winding fibers 6a with the core fibers to increase the strength of the spun yarn 9.

As shown in Figure 2, in accordance with the present embodiment, the second nozzle 17 forms a part of the hollow guide shaft 13, and is composed of second nozzle holes 13a, 13a, ... and the peripheries of the second nozzle holes 13a, 13a. ... Each of the second nozzle holes 13a is in communication with the inside of the yarn path 13b in the middle of the yarn path 13b.

Air is fed through the second nozzle holes 13a, 13a, ... by air supply means (not shown in the drawings) and ejected into the yarn path 13b.

The second air nozzle 17 is different from the first air nozzle 16 in the place to which air is ejected and in the place in which a whirling air current is generated.

0n the other hand, the second air nozzle 17 is the same as the first air nozzle 16 in the following points: the nozzle holes are arranged around the axis of the yarn feed-out direction A at equal intervals, the direction in which air is ejected from each of the nozzle holes is the same as that in which a whirling air current is generated, and the whirling air current is provided with the component acting in the yarn feed-out direction A. Further, the second air nozzle 17 is the same as the first air nozzle 16 in the whirling direction of the whirling air current.

Each of the second nozzle holes 13a is formed generally perpendicularly to the yarn feed-out direction A, and more specifically, the second nozzle holes 13a are inclined toward the yarn feed-out direction A side. The second nozzle holes 13a correspond to areas that are immediately adjacent to and in communication with the yarn path 13b (the peripheries of the openings in communication with the yarn path 13b). The direction in which the second nozzle holes 13a are formed allows the flow of air ejected from each of the second nozzle holes 13a to be provided with the component acting toward the yarn feed-out direction A.

As previously described, air injected by the first air nozzle 16 makes the air pressure in the yarn path 13b positive with respect to the air pressure in the inversion chamber 14. However, on the contrary, air injected from the second nozzle holes 13a makes the air pressure in the yarn path 13b negative with respect to the air pressure in the inversion chamber 14. This prevents the winding fibers 6a from being discharged from the whirling air current generating chamber 15 directly to the outside without being entangled with the core fibers. This in turn further reduces a possible fiber loss.

As shown in Figure 5, each of the second nozzle holes 13a is formed to communicate with the inside of the yarn path 13b, which is a cylindrical space, from a tangential direction of the yarn path 13b. Thus, air ejected from each of the second nozzle holes 13a generates a whirling air current B2 in the yarn path 13b. The whirling air current B2 has not only the component acting in the yarn feed-out direction A but also the component acting around the axis extending in the yarn feed-out direction A.

In particular, the plurality of second nozzle holes 13a, 13a, ... are spaced at equal intervals in the circumferential direction of the yarn path 13b, which is a cylindrical space, and further, air is uniformly injected through all of the second nozzle holes 13a, 13a, ... Thus, a whirling air current B2 that is uniform in the circumferential direction (around the axis extending in the yarn feed-out direction A) is generated in the yarn path 13b.

The second nozzle holes 13a, 13a, ... configured as shown in Figure 5 generate a counterclockwise whirling air current B2 in the yarn path 13b.

As shown in Figures 3 and 5, the second air nozzle 17 is the same as the first air nozzle 16 in the whirling direction of the whirling air current.

Thus, the spun yarn 9 twisted in the inversion chamber 14 by air injected through the first air nozzle 16 is twisted again (additionally twisted) in the yarn path 13b by air injected through the second air nozzle 17. This further enhances the entanglement of the winding fibers 6a with the core fibers to increase the strength of the spun yarn 9.

Now, a description will be given of a spinning method using the spinning device 10.

The spinning method comprises an introducing step of introducing a fiber bundle 6 into the spinning device 10, a yarn discharging step of injecting air through the first air nozzle 16 and the auxiliary nozzle 19, and a spinning step of injecting air through the first air nozzle 16 and the second air nozzle 17.

In the introducing step, an operator or the like carries the end of the fiber bundle 6 to the neighborhood of an inlet of the fiber introducing path 11a (or into the fiber introducing path 11a).

The yarn discharging step is executed by injecting air through the first air nozzle 16 and the auxiliary nozzle 19 at the above state (the end of the fiber bundle 6 lies in the neighborhood of the inlet of the fiber introducing path 11a). The air injection through the first air nozzle 16 and the auxiliary nozzle 19 sucks the external air into the fiber introducing path 11a, while the fiber bundle 6 is drawn into the fiber introducing path 11a and then guided into the inversion chamber 14. The air is sucked into the fiber introducing path 11a because the air injection through the first air nozzle 16 and the auxiliary nozzle 19 makes the air pressure in the inversion chamber 14 and the yarn path 13b negative with respect to the air pressure in the fiber introducing path 11a, with a resultant air flow that sucks the external air into the fiber introducing path 11a. The direction of the whirling air current B1 generated by the first air nozzle 16 is opposite to that of the whirling air current B3 generated by the auxiliary nozzle 19.

The fiber bundle 6 is introduced into the yarn path 13b via the inversion chamber 14. The auxiliary nozzle 19 then twists the fiber bundle 6 between the auxiliary nozzle 19 and the needle 18. The fiber bundle 6 is thus converged as the core fibers. On the other hand, the remaining fibers (winding fibers 6a), which are not twisted and thus do not constitute the core fibers of the fiber bundle 6, wind around the core fibers by the whirling air current B1 generated by the first air nozzle 16 in the direction of the whirling air current B1. The core fibers are twisted by the auxiliary nozzle 19 and start to be untwisted upon having passed through the auxiliary nozzle 19. The untwisting occurs in the direction opposite to that of the whirling air current B3, generated by the auxiliary nozzle 19, that is, in the same direction as that of the whirling air current B1, generated by the first air nozzle 16. Thus, the untwisting of the core fibers allows the winding fibers 6a to wind more firmly around the core fibers. Then, the winding fibers 6a wind around the non-twisted core fibers by untwisting to generate a kind of yarn.

Once the kind of yarn is generated and discharged from the yarn path 13b, the air injection through the auxiliary nozzle 19 is stopped to end the yarn discharging step. The process then shifts to a normal spinning step.

In the spinning step, air injection is started through the second air nozzle 17; air is injected through both the first air nozzle 16 and the second air nozzle 17. The fiber bundle 6 is guided to the inversion chamber 14, where it is spun as previously described. The spun yarn 9 is then fed out to the outside of the spinning device 10 via the yarn path 13b. The kind of yarn generated in the yarn discharging step is cut during an operation of the yarn splicing means (not shown in the drawings).

A stop step is executed to suspend or end spinning. In this case, the air injection through the first air nozzle 16 and the second air nozzle 17 is ended.

The spinning step is executed while spinning is being continued. During the execution of the spinning step, air is continuously injected through both the first air nozzle 16 and the second air nozzle 17.

Thus, first, the air injection through the first air nozzle 16 generates, in the yarn path 13b, an air flow moving in the direction opposite to the yarn feed-out direction A. However, the air injection through the second air nozzle 17 generates an air flow which cancels the above air flow and which moves in the opposite direction (that is, the yarn feed-out direction A). During the execution of the spinning operation, an air flow moving in the yarn feed-out direction A is continuously generated in the yarn path 13b. This prevents the winding fibers 6a from being disadvantageously discharged from the whirling air current generating chamber 15 to the outside. This in turn reduces a possible fiber loss.

The direction of an air flow generated in the yarn path 13b is not fixedly determined by the largeness or smallness of the pressure of the injection through the the first air nozzle 16 and the second air nozzle 17. The direction of the air flow is determined by a set of factors such as the opening areas of the nozzle holes 12a, 13a and shapes of the inversion chamber 14 and whirling air current generating chamber 15.

Second, the spun yarn 9 already twisted by the first air nozzle 16 is twisted again in the same direction by the second air nozzle 17, located downstream side of the first air nozzle 16 in the yarn feed-out direction A. During the execution of a spinning operation, the spun yarn 9 is continuously additionally twisted. This increases the intensity of the spun yarn 9.

The reduction in fiber loss and the increase in the strength of the spun yarn 9 described above can be achieved by air injection through both the first air nozzle 16 and the second air nozzle 17 on the condition that the amount of air injected (the amount of air injected during a unit time) only through the first air nozzle 16 is the same as the total amount of air injected (the amount of air injected during a unit time) through both the first air nozzle 16 and the second air nozzle 17. Conversely, with the amount of fiber loss and the strength of the spun yarn 9 kept unchanged, the amount of air injected can be reduced by injecting air through both the first air nozzle 16 and the second air nozzle 17 instead of injecting air only through the first air nozzle 16.

While the present invention has been described with respect to preferred embodiments thereof, it will be apparent to those skilled in the art that the disclosed invention may be modified in numerous ways and may assume many embodiments other than those specifically set out and described above. Accordingly, it is intented by the appended claims to cover all modifications of the present invention that fall within the true spirit and scope of the invention.