Claims:I/We claim:

1. A guide tube (50, 50A, 50B, 50C, 50D, 50E, 50F, 50G, 50H, 50I) that assists unwinding of a yarn from a yarn feeding bobbin (SB), comprising:
a cylindrical first tube part (51) extending along a predetermined reference axis (L); and
a second tube part (52, 52A, 52B, 52C, 52D, 52E, 52F, 52G, 52H, 52I) that extends along the reference axis (L), has a first end and a second end, and the first end is connected to an upstream end of the first tube part (51) in a traveling direction of the yarn unwound from the yarn feeding bobbin (SB), wherein
the second tube part (52, 52A, 52B, 52C, 52D, 52E, 52F, 52G, 52H, 52I) has a portion having a non-circular cross-sectional shape along a direction orthogonal to the reference axis (L).

2. The guide tube (50, 50A, 50B, 50C, 50D, 50E, 50F, 50G, 50H, 50I) as claimed in claim 1, wherein the second tube part (52, 52A, 52B, 52C, 52D, 52E, 52F, 52G, 52H, 52I) has a tapered shape that gradually expands from the first end thereof toward the second end thereof.

3. The guide tube (50, 50A, 50B, 50C, 50D, 50E, 50F, 50G, 50H, 50I) as claimed in claim 1 or 2, wherein the portion having the non-circular cross-sectional shape of the second tube part (52, 52A, 52B, 52C, 52D, 52E, 52F, 52G, 52H, 52I) is provided in the second end thereof.

4. The guide tube (50, 50A, 50B, 50C, 50D, 50E, 50F, 50G, 50H, 50I) as claimed in claim 3, wherein
the second tube part (52, 52A, 52B, 52C, 52D, 52E, 52F, 52G, 52H, 52I) has a bent portion (W1, W2) that protrudes outward or inward, and
the portion having the non-circular shape of the second tube part (52, 52A, 52B, 52C, 52D, 52E, 52F, 52G, 52H, 52I) is constituted by the bent portion (W1, W2).

5. The guide tube (50, 50A, 50B, 50C, 50D, 50E, 50F, 50G, 50H, 50I) as claimed in claim 4, wherein the second tube part (52, 52A, 52B, 52C, 52D, 52E, 52F, 52G, 52H, 52I) has three or more bent portions (W1) that protrude outward.

6. The guide tube (50, 50A, 50B, 50C, 50D) as claimed in claim 5, wherein the portion having the non-circular shape of the second tube part (52, 52A, 52B, 52C, 52D) has a regular polygonal shape in which the bent portions (W1) and linear portions (WS) connecting the bent portions (W1) are provided alternately.

7. The guide tube (50E, 50F, 50G, 50H, 50I) as claimed in claim 4, wherein
the second tube part (52E, 52F, 52G, 52H, 52I) has as the bent portion an outwardly bent portion (W1) that is the bent portion protruding outward, and an inwardly bent portion (W2) that is a bent portion protruding inward, and linear portions (WS) connecting the outwardly bent portion (W1) and the inwardly bent portion (W2), and
the outwardly bent portion (W1) is provided in plurality,
the inwardly bent portion (W2) is provided in the same number as the outwardly bent portion (W1),
the outwardly bent portion (W1) and the inwardly bent portion (W2) are provided alternately in the circumferential direction of the second tube part (52E, 52F, 52G, 52H, 52I), and the outwardly bent portion (W1) and the inwardly bent portion (W2) are connected by the linear portion (WS).

8. The guide tube (50E, 50F, 50G, 50H, 50I) as claimed in one of claims 4 to 7, wherein the bent portions provided in the second tube part (52E, 52F, 52G, 52H, 52I) extend from the second end to the first end thereof and a degree of protrusion of the bent portions gradually decreases as one goes toward the first end thereof.

9. The guide tube (50, 50A, 50B, 50C, 50D, 50E, 50F, 50G, 50H, 50I) as claimed in one of claims 1 to 8, wherein a shape of the first end of the second tube part (52, 52A, 52B, 52C, 52D, 52E, 52F, 52G, 52H, 52I) is circular.

10. A yarn winding device comprising: in a yarn traveling path, in order from a supply yarn side, a yarn unwinding assisting device (20) including the guide tube (50, 50A, 50B, 50C, 50D, 50E, 50F, 50G, 50H, 50I) as claimed in one of claims 1 to 9, a tension applying device (22), a yarn joining device (26), a yarn monitoring device (28), and a winding device (14).
, Description:BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a guide tube that assists in unwinding a yarn from a bobbin.

2. Description of the Related Art
An automatic winder that winds a yarn around a winding bobbin while unwinding the yarn from a yarn feeding bobbin is known in the art. In such an automatic winder a balloon of the yarn is formed around the yarn feeding bobbin when the yarn is unwound from the yarn feeding bobbin. Such a balloon is formed as the yarn unwound from the yarn feeding bobbin is swung by a centrifugal force. The automatic winder includes a yarn unwinding assisting device that assists in unwinding the yarn to prevent the yarn from being swung excessively when the yarn is being unwound.
The yarn unwinding assisting device includes a guide tube that is placed around a core tube of the yarn feeding bobbin. In such a yarn unwinding assisting device, the yarn is prevented from being swung excessively by causing the guide tube to contact the balloon. A yarn unwinding assisting device having such a guide tube is disclosed in, for example, Japanese Patent Application Laid-Open No. 2013-67459.
When the speed of unwinding the yarn from the yarn feeding bobbin is increased, the speed at which the yarn is swung increases, and the centrifugal force that acts on the yarn also increases. This increases the expansion of the balloon of the yarn unwound from the yarn feeding bobbin.

SUMMARY OF THE INVENTION
One object of the present invention is to provide a guide tube that can efficiently suppress the expansion of the balloon of the yarn.
According to one aspect of the present invention, a guide tube that assists unwinding of a yarn from a yarn feeding bobbin includes a cylindrical first tube part extending along a predetermined reference axis; and a second tube part that extends along the reference axis, has a first end and a second end, and the first end is connected to an upstream end of the first tube part in a traveling direction of the yarn unwound from the yarn feeding bobbin, wherein the second tube part has a portion having a non-circular cross-sectional shape along a direction orthogonal to the reference axis.
According to another aspect of the present invention, a yarn winding device includes, in a yarn traveling path, in order from a supply yarn side, a yarn unwinding assisting device including the guide tube, a tension applying device, a yarn joining device, a yarn monitoring device, and a winding device.
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of an automatic winder according to an embodiment.
FIG. 2 is a side view of a winding unit.
FIG. 3 is a side view of a structure around a guide tube of a yarn unwinding assisting device.
FIG. 4 is a side view of the guide tube.
FIG. 5 is an end view of a second tube part along a line V-V shown in FIG. 4.
FIG. 6 is a perspective view of the guide tube viewed from the side of the second tube part.
FIG. 7 is a schematic diagram showing a trajectory of a yarn that moves while abutting on a lower end of the second tube part when the guide tube is viewed from the second tube part side.
FIGS. 8A to 8D are perspective views of a guide tube according to a modification when viewed from the second tube part side.
FIG. 9 is a side view of the guide tube according to the modification.
FIG. 10 is an end view of the second tube part along a line X-X shown in FIG. 9.
FIG. 11 is a perspective view of the guide tube shown in FIG. 9 when viewed from the second tube part side.
FIGS. 12A to 12D are perspective views of a guide tube according to another modification when viewed from the second tube part side.

DETAILED DESCRIPTION
Exemplary embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same components will be denoted by the same reference symbols, and redundant description thereof will be omitted.
As shown in FIG. 1, an automatic winder 1 includes a plurality of winding units (yarn winding devices) 3, a machine control device 5, and a doffing device 7. These devices are arranged side by side.
The machine control device 5 communicates with the winding units 3. An operator of the automatic winder 1 manages the winding units 3 collectively by appropriately operating the machine control device 5. The machine control device 5 includes a display screen 5a and one or more input keys 5b. The display screen 5a displays information about the setting contents and/or a state of the winding unit 3, and the like. The setting operation of the winding unit 3 is performed by the operator by appropriately operating the input keys 5b.
Each winding unit 3 unwinds a yarn Y from a yarn feeding bobbin (bobbin) SB and winds the unwound yarn Y around a winding bobbin WB while traversing the yarn Y. The winding unit 3 forms a package P by this operation. The yarn Y may contain a core yarn. The core yarn is, for example, a monofilament yarn, a yarn, or the like.
The doffing device 7 travels to the position of the winding unit 3 when the package P becomes full (a state in which a specific amount of the yarn has been wound) in this winding unit 3, and the full package is removed from the winding unit 3 and an empty winding bobbin WB is set in the winding unit 3.
Next, a configuration of the winding unit 3 will be described with reference to FIG. 2. As shown in FIG. 2, each winding unit 3 includes a unit controller 10, a yarn feeding device 12, and a winding device 14.
The unit controller 10 includes, for example, a CPU (Central Processing Unit) and a ROM (Read Only Memory). The ROM stores therein a computer program that controls various components of the winding unit 3. The CPU executes the computer program stored in the ROM. The unit controller 10 controls various components of the winding unit 3 by cooperation between hardware and software. The unit controller 10 communicates with the machine control device 5. As a result, the operations of the winding units 3 provided in the automatic winder 1 can be centrally managed by the machine control device 5.
The yarn feeding device 12 is a support mechanism that supports the yarn feeding bobbin SB placed on a transport tray at a predetermined position. The yarn Y is unwound from the yarn feeding bobbin SB, and the unwound yarn Y is drawn upward from the yarn feeding bobbin SB. In this manner, the yarn feeding device 12 feeds the yarn Y. The yarn feeding device 12 is not limited to the transport tray device, and may be, for example, a magazine device.
The winding device 14 includes a cradle 16 and a winding drum 18. The cradle 16 includes a pair of not shown rotation supports. The cradle 16 rotatably supports the winding bobbin WB (or the package P) by holding the winding bobbin WB between the rotation supports. The state of the cradle 16 can be switched between a state in which the package P supported by the cradle 16 is in contact with the winding drum 18 and a state in which the package P is separated from the winding drum 18.
The winding drum 18 traverses the yarn Y on the surface of the package P and rotates the package P as well. The winding drum 18 is driven to rotate by a not shown drum drive motor. With the outer peripheral surface of the package P in contact with the winding drum 18, the package P is driven to rotate following the rotation of the winding drum 18. A spiral traverse groove has been formed on the outer peripheral surface of the winding drum 18. The yarn Y unwound from the yarn feeding bobbin SB is wound on the surface of the package P while being traversed by the traverse groove for a specific width. As a result, the package P having a specific winding width can be formed.
Each winding unit 3 includes a yarn unwinding assisting device 20, a tension applying device 22, a tension detecting device 24, a yarn joining device 26, a yarn monitoring device 28, and a wax applying device 30 in the yarn traveling path and between the yarn feeding device 12 and the winding device 14 in this order from the yarn feeding device 12 side. A first capturing and guiding device 32 and a second capturing and guiding device 34 are arranged near the yarn joining device 26.
The yarn unwinding assisting device 20 includes a guide tube 50 that covers a core tube of the yarn feeding bobbin SB. The guide tube 50 has a substantially cylindrical shape. The guide tube 50 is arranged such that it can contact the balloon of the yarn Y formed above the yarn feeding bobbin SB. The balloon is formed as the yarn Y unwound from the yarn feeding bobbin SB is swung by a centrifugal force. By causing the guide tube 50 to contact the balloon, the yarn Y constituting the balloon is prevented from being swung excessively. As a result, the yarn Y can be appropriately unwound from the yarn feeding bobbin SB.
The tension applying device 22 applies a predetermined tension to the traveling yarn Y. In the present embodiment, the tension applying device 22 is a gate type device in which movable comb teeth are arranged with respect to fixed comb teeth. The movable-side comb teeth are urged so that the comb teeth are engaged with each other. The yarn Y is passed between the comb teeth of the tension applying device 22 and tension is applied to the yarn Y when the yarn Y bends when the yarn Y passes between the comb teeth that are in the engaged state. The operation of the tension applying device 22 is controlled by the unit controller 10.
The tension detecting device 24 detects (measures) the tension on the traveling yarn Y at a position between the yarn feeding device 12 and the winding device 14. The tension detecting device 24 outputs to the unit controller 10 a tension measurement signal indicating the measured value of the tension on the yarn Y.
When the yarn Y is disconnected for some reason between the yarn feeding device 12 and the winding device 14, the yarn joining device 26 joins the yarn Y (lower yarn) on the yarn feeding device 12 side and the yarn Y (upper yarn) on the winding device 14 side. In the present embodiment, the yarn joining device 26 is configured as a splicer device that joins the yarns by twisting yarn ends by using a swirling airflow generated by compressed air.
The yarn monitoring device 28 monitors the state of the yarn Y traveling on the yarn path and detects the presence or absence of a yarn defect based on the monitored information. The yarn monitoring device 28 detects, for example, a thickness abnormality of the yarn Y and/or presence of a foreign substance in the yarn Y as the yarn defect. The yarn monitoring device 28 also detects whether the yarn has run out, that is, whether the yarn Y is present in the yarn path. A cutter 29 capable of cutting the yarn Y is arranged near the yarn monitoring device 28. The cutter 29 is operated by the yarn monitoring device 28.
The wax applying device 30 is arranged between the winding device 14 and the yarn monitoring device 28. The wax applying device 30 applies wax to the yarn Y traveling from the yarn monitoring device 28 to the winding device 14.
Next, the configuration of the yarn unwinding assisting device 20 will be described in detail. As shown in FIG. 3, the yarn unwinding assisting device 20 assists unwinding of the yarn Y from the yarn feeding bobbin SB at a position above the yarn feeding bobbin SB that has been supported in an upright state by the yarn feeding device 12. The yarn unwinding assisting device 20 controls the size of the balloon formed by the yarn Y unwound from the yarn feeding bobbin SB, and applies an appropriate tension to the yarn Y.
Specifically, the yarn unwinding assisting device 20 includes a guide tube 50, a fixed tube 54, and an elevating mechanism 56. The fixed tube 54 is a substantially cylindrical member whose upper and lower ends are open. The fixed tube 54 is fixed to a frame of the winding unit 3 via a holder 58. A yarn guide 55 is arranged at the lower end of the fixed tube 54.
The guide tube 50 is a substantially cylindrical member with upper and lower ends open. The guide tube 50 is supported by the elevating mechanism 56 via a holder 57. A lower part of the fixed tube 54 is inserted inside an upper part of the guide tube 50. The guide tube 50 is moved up and down by the elevating mechanism 56 to cover an upper part of the yarn feeding bobbin SB. The central axis of the yarn feeding bobbin SB and the central axes of the fixed tube 54 and the guide tube 50 coincide with each other.
The yarn unwinding assisting device 20 includes a sensor that detects the height of a chase portion T formed by the yarn Y wound around the yarn feeding bobbin SB. The position of the chase portion T descends as more yarn Y is unwound. The elevating mechanism 56 lowers the guide tube 50 according to the height of the chase portion T detected by the sensor.
The fixed tube 54 regulates the expansion of the balloon while the fixed tube 54 is in a fixed state. The guide tube 50 moves following the unwinding of the yarn Y from the yarn feeding bobbin SB to regulate the expansion of the balloon. Thus, the fixed tube 54 and the guide tube 50 assist unwinding of the yarn Y by regulating the expansion of the balloon.
Next, details of the guide tube 50 will be described. The guide tube 50 is shown in FIGS. 4 to 6. This guide tube 50 assists in unwinding the yarn Y from the yarn feeding bobbin SB as described above. The guide tube 50 includes a first tube part 51 and a second tube part 52. The first tube part 51 has a cylindrical shape extending along a central axis (predetermined reference axis) L thereof. That is, the first tube part 51 has a circular cross-section in the direction orthogonal to the central axis L.
The second tube part 52 extends along the central axis L. The second tube part 52 is connected to a lower end of the first tube part 51. That is, the second tube part 52 is connected to, between the two ends (upper and lower ends) along the central axis L of the first tube part 51, the lower end that is an upstream end in the traveling direction of the yarn Y unwound from the yarn feeding bobbin SB.
The second tube part 52 has a tapered shape whose diameter increases toward a lower end thereof. That is, the second tube part 52 has a tapered shape that gradually expands as one goes from the end (first end) connected to the first tube part 51 (upper end) to the end (second end) on the other side of the first end connected to the first tube part 51 (lower end).
The second tube part 52 has a portion that has a non-circular cross-section in the direction orthogonal to the central axis L. That is, a portion of the second tube part 52 has a cross section that is not a true circle. The meaning of not a true circle is, for example, a shape such as that of English letter C which is not a complete ring but has a cut part. In other words, even if the second tube part 52 has a cut part, the cross-sectional shape of the second tube part 52 at a position where the yarn Y abuts the inner surface of the second tube part 52 when the yarn is swung inside the second tube part 52 is circular.
In the present embodiment, the second tube part 52 has a portion having a quadrangular cross-sectional shape as the portion having the non-circular cross-sectional shape in the direction orthogonal to the central axis L. The portion having the quadrangular cross-sectional shape is provided in the second end of the second tube part 52. That is, the portion of the second tube part 52 whose cross-sectional shape is the quadrangular is provided in the second end of the second tube part 52 that is on the other side of the first end that is connected to the first tube part 51.
In this manner, the second tube part 52 has four outwardly bent portions (bent portions) W1 that protrude outward. The portion of the second tube part 52 having the quadrangular shape in cross section is constituted by the four bent portions W1 and linear portions WS that connect the bent portions W1. In the present embodiment, the inner angle of the bent portion W1 at the second end of the second tube part 52 is 90°. The bent portions W1 are provided at the second end of the second tube part 52 and extend from the second end to the first end of the second tube part 52.
The degree of protrusion of the bent portion W1 provided in the second tube part 52 gradually decreases toward the first end that is connected to the first tube part 51. The degree of protrusion refers to the amount of deviation from the first tube part 51 when the second tube part 52 is viewed from the axial direction. That is, when the degree of protrusion is zero, the first tube part 51 and the second tube part 52 have the same shape. Then, as shown in FIG. 5, the shape of the first end of the second tube part 52 that is connected to the first tube part 51 is circular. That is, the cross-sectional shape of the second tube part 52 gradually changes from the quadrangular shape to the circular shape from the second end to the first end of the second tube part 52.
Next, a trajectory of the yarn Y when the yarn Y unwound from the yarn feeding bobbin SB and swung moves along the inner peripheral surface of the second tube part 52 will be described. Here, the trajectory of the yarn Y moving along the inner peripheral surface of the second end of the second tube part 52 will be described while referring to FIG. 7. Note that, FIG. 7 shows only the second end of the second tube part 52 and the yarn Y (cross section of the yarn Y) that is in contact with the second end of the second tube part 52.
As shown in FIG. 7, the yarn Y is swung by the centrifugal force, and moves in the circumferential direction along an inner peripheral surface 53 of the second tube part 52 in a state of being in contact with the inner peripheral surface 53. The trajectory of the yarn Y is referred to as trajectory K. The four inner surfaces constituting the inner peripheral surface 53 of the second tube part 52 are referred to as inner surfaces 53a. That is, the yarn Y is swung so as to sequentially contact the four inner surfaces 53a.
As described above, the second tube part 52 is provided with the bent portions W1. For this reason, when the yarn Y moves from the inner surface 53a to which the yarn Y is currently in contact to the next inner surface 53a via the bent portion W1, the yarn Y temporarily separates from the inner peripheral surface 53 and collides at a colliding position Z of the next inner surface 53a. When the yarn Y contacts the next inner peripheral surface 53 at the colliding position Z, the moving direction of the yarn Y is suddenly changed, so that an impact is applied to the yarn Y. Due to this impact the yarn Y vibrates (the wavy trajectory K in FIG. 7). Due to such vibrations, the expansion of the balloon of the yarn Y is suppressed, and the centrifugal force applied to the yarn Y is reduced. In the present embodiment, while the yarn Y makes one round along the inner peripheral surface 53 of the second tube part 52, the impact is applied four times to the yarn Y at the colliding positions Z of the inner surfaces 53a.
As described above, in the guide tube 50, the yarn Y unwound from the yarn feeding bobbin SB passes through the second tube part 52 and then passes through the first tube part 51. That is, the second tube part 52 guides the yarn Y to the first tube part 51 after suppressing the expansion of the balloon of the yarn Y unwound from the yarn feeding bobbin SB. Moreover, the first tube part 51 suppresses the expansion of the balloon by the inner peripheral surface. The second tube part 52 has the portion having the non-circular cross-sectional shape. That is, in the present embodiment, the second tube part 52 has the portion having the quadrangular shape in cross section. Accordingly, when the yarn Y is swung in a state in which the balloon of the yarn Y is in contact with the inner peripheral surface 53 of the second tube part 52, impact is applied to the swinging yarn Y due to the presence of the portion having the quadrangular shape whereby the yarn Y vibrates. Due to such vibrations, the strength of the centrifugal force applied to the yarn Y fluctuates and the formation of the balloon is inhibited. As described above, because the guide tube 50 has the second tube part 52 having the portion with the quadrangular shape, the expansion of the balloon of the yarn Y can be efficiently suppressed.
The guide tube 50 suppresses the yarn Y from being excessively drawn because of the centrifugal force by suppressing the balloon from expanding. With such a guide tube 50, the slack of the yarn Y in an unintended part, and the like can be suppressed, and the yarn Y is prevented from coming out of the yarn feeding bobbin SB in a circular shape (so-called sluffing). Further, in the guide tube 50, it is possible to suppress the undesired winding of the yarn Y unwound from the yarn feeding bobbin SB around the core tube of the yarn feeding bobbin SB, and the tension of the yarn Y when the yarn Y is pulled out from the yarn feeding bobbin SB can be reduced. With the guide tube 50, it is possible to increase the unwinding speed of the yarn Y while suppressing the breaking of the yarn Y.
The second tube part 52 has a tapered shape whose diameter increases toward the second end thereof. The second tube part 52 of the guide tube 50 can have a shape that matches the shape of the chase portion T. As a result, in the guide tube 50, it is possible to bring the chase portion T and the second tube part 52 closer to each other, and the expansion of the balloon of the yarn Y can be further suppressed.
The portion of the second tube part 52 having a quadrangular cross-sectional shape is provided at the second end of the second tube part 52. The vibrations generated in the yarn Y in the portion of the second tube part 52 in which the second tube part 52 has the quadrangular shape are efficiently conveyed to the balloon in the portion (in which the balloon does not contact the guide tube 50) between an unwinding position at which the yarn Y of the yarn feeding bobbin SB is unwound and the second tube part 52. As a result, with the guide tube 50, it is possible to more efficiently suppress the expansion of the balloon of the yarn Y.
The portion of the second tube part 52 having the quadrangular shape is constituted by the four bent portions W1 and the linear portions WS that connect the bent portions W1. Thus, with the guide tube 50, it is possible to suppress the expansion of the balloon of the yarn Y as the impact is applied to the yarn Y in the portion of the second tube part 52 in which the bent portions W1 are provided. The four bent portions W1 are provided in the second tube part 52. Therefore, in the guide tube 50, the impact can be efficiently applied to the yarn Y by the four bent portions W1, and the expansion of the balloon of the yarn Y can be further suppressed.
The degree of protrusion of the bent portion W1 provided in the second tube part 52 gradually decreases toward the first end of the second tube part 52 that is connected to the first tube part 51. Therefore, the second tube part 52 can smoothly guide the yarn Y toward the cylindrical first tube part 51. The first end of the second tube part 52 that is connected to the first tube part 51 has the circular shape. Therefore, the second tube part 52 can guide the yarn Y more smoothly toward the first tube part 51.
The embodiments of the present invention have been described above; however, the present invention is not limited to the embodiments described above. For example, the portion of the second tube part 52 having the non-circular cross-sectional shape is not limited to the portion having the quadrangular shape shown in FIG. 6. That is, as long as the portion has a non-circular shape, this portion of the second tube part may have a polygonal shape instead of the quadrangular shape. For example, like a guide tube 50A shown in FIG. 8A, a portion of a second tube part 52A can have a triangular shape with three bent portions W1 and three linear portions WS. Similarly, for example, like a guide tube 50B shown in FIG. 8B, a portion of a second tube part 52B can have a pentagonal shape with five bent portions W1 and five linear portions WS. For example, like a guide tube 50C shown in FIG. 8C, a portion of a second tube part 52C can have a hexagonal shape with six bent portions W1 and six linear portions WS. For example, like a guide tube 50D shown in FIG. 8D, a portion of a second tube part 52D can have an octagonal shape with eight bent portions W1 and eight linear portions WS. Even in these cases, the guide tubes 50A to 50D can exhibit the same effects as the guide tube 50 in the above embodiment. The triangular shape, quadrangular shape, pentagonal shape, hexagonal shape, and octagonal shape can be referred to as regular polygonal shapes.
Moreover, while the portion of the second tube part has three or more bent portions W1 in the examples shown in FIG. 6 and FIGS. 8A to 8D, the portion of the second tube part can have one or two bent portions W1. Even in this case, because the guide tube has the bent portions W1, the guide tube can apply an impact to the yarn Y and can provide the same effect as the guide tube 50 in the above embodiment.
In addition to the outwardly bent portions W1, the second tube part 52 can have inwardly bent portions that protrude inward. Specifically, as shown in FIGS. 9 to 11, a guide tube 50E is constituted by the first tube part 51 and a second tube part 52E. The second tube part 52E has four bent portions W1 protruding outward, and four bent portions (inwardly bent portions) W2 protruding inward. The bent portions W1 and W2 are provided alternately in the circumferential direction of the second tube part 52E, and adjacent bent portions W1 and W2 are connected by the linear portions WS. The inner angle of the bent portion W1 is less than 90°. The inner angle of the bent portion W2 is larger than 180°. Thus, the portion of the second tube part 52E having a non-circular cross-sectional shape is constituted by four bent portions W1 and four bent portions W2.
Even in this case, because the second tube part 52E can efficiently apply an impact to the yarn Y when the yarn Y is swung by the alternately provided bent portions W1 and W2, the expansion of the balloon of the yarn Y can be suppressed. Thus, the guide tube 50E can achieve the same effect as the guide tube 50 in the above embodiment. In the guide tube 50E, the magnitude of the impact applied to the yarn Y can be adjusted by changing the size of the inner angle of the bent portions W1 and W2.
Also, for example, it is not limited that the second tube part 52E has four bent portions W1 and W2 as shown in FIG. 11 as the portion having the non-circular cross-sectional shape. That is, the second tube part can have a plurality of bent portions W1 and the same number of the bent portions W2 as the bent portions W1. For example, like a guide tube 50F shown in FIG. 12A, a second tube part 52F thereof can have a portion having a non-circular shape with three bent portions W1 and three bent portions W2. Similarly, for example, like a guide tube 50G shown in FIG. 12B, a second tube part 52G can have a portion having a non-circular shape with five bent portions W1, five bent portions W2, and ten linear portions WS (in FIG. 12B some of these reference letters have been omitted) connecting these bent portions. For example, like a guide tube 50H shown in FIG. 12C, a second tube part 52H can have a portion having a non-circular shape with six bent portions W1, six bent portions W2, and twelve linear portions WS (in FIG. 12C some of these reference letters have been omitted) connecting these bent portions. For example, like a guide tube 50I shown in FIG. 12D, a second tube part 52I can have a portion having a non-circular shape with eight bent portions W1, eight bent portions W2, and sixteen linear portions WS (in FIG. 12D some of these reference letters have been omitted) connecting these bent portions.
Moreover, while the portion of the second tube part has three or more bent portions W1 and three or more bent portions W2 in the examples shown in FIG. 11 and FIGS. 12A to 12D, the portion of the second tube part can have one or two bent portions W1 and one or two bent portions W2. In the second tube part, the number of bent portions W1 and the number of bent portions W2 can be different from each other. Even in this case, because the guide tube has the bent portions W1 and W2, the guide tube can apply an impact to the yarn Y and can provide the same effect as the guide tube 50 in the above embodiment.
Further, the second tube part can have only one or more bent portions W2 that protrude inwardly. Even in this case, because the guide tube has the bent portion W2, the guide tube can apply an impact to the yarn Y and can provide the same effect as the guide tube 50 in the above embodiment.
Further, it is not limited that the portion having the non-circular cross-sectional shape of the second tube part 52 is formed by the bent portion W1. In the second tube part 52, the portion having the non-circular cross-sectional shape can be formed by a configuration other than the bent portions W1 and the bent portions W2. The cross-sectional shape of the second tube part can be, for example, elliptical. Moreover, the second tube part 52 does not have to have a tapered shape that gradually expanding toward the second end thereof. The portion having the non-circular cross-sectional shape need not be provided at the second end of the second tube part 52. The portion having the non-circular cross-sectional shape can be provided at any position of the second tube part 52.
It is not limited that the degree of protrusion of the bent portion W1 of the second tube part 52 gradually decreases toward the first end that is connected to the first tube part 51. That is, the degree of protrusion of the bent portion W1 of the second tube part 52 can be constant. Further, the shape of the first end of the second tube part 52 that is connected to the first tube part 51 does not have to be circular.
At least some of the embodiments and the various modifications described above may be arbitrarily combined.
According to one aspect of the present invention, a guide tube that assists unwinding of a yarn from a bobbin includes a cylindrical first tube part extending along a predetermined reference axis; and a second tube part that extends along the reference axis. The second tube part has a first end and a second end, and the first end is connected to an upstream end of the first tube part in a traveling direction of the yarn unwound from the yarn feeding bobbin. The second tube part has a portion having a non-circular cross-sectional shape along a direction orthogonal to the reference axis.
In this guide tube, the yarn unwound from the bobbin passes through the second tube part and then passes through the first tube part. That is, the second tube part guides the yarn to the first tube part while suppressing expansion of the balloon of the yarn unwound from the bobbin. In the first tube part, the expansion of the balloon is suppressed by the inner peripheral surface. Here, the second tube part includes a portion having a non-circular cross-sectional shape. Therefore, when the yarn is swung while the balloon is in contact with the inner peripheral surface of the second tube part, an impact is applied to the swinging yarn due to the presence of the portion having the non-circular cross-sectional shape, and the yarn vibrates. Due to such vibrations, the magnitude of the centrifugal force applied to the yarn varies and the formation of the balloon is inhibited. As described above, the guide tube includes the second tube part having the portion with the non-circular cross-sectional shape, whereby the expansion of the balloon of the yarn can be efficiently suppressed.
In the above guide tube, the second tube part has a tapered shape that gradually expands from the first end thereof toward the second end thereof. In this case, the second tube part of the guide tube can have a shape that matches the chase portion formed by a yarn wound around the bobbin. As a result, in the guide tube, it is possible to arrange the chase portion and the second tube part closer to each other, and the expansion of the balloon of the yarn can be further suppressed.
In the above guide tube, the portion having the non-circular cross-sectional shape of the second tube part is provided in the second end of the second tube part. In this case, the vibration generated in the yarn in the portion of the second tube part having the non-circular cross-sectional shape can be efficiently transmitted to the balloon in the portion between an unwinding position of the yarn on the bobbin and the second tube part. Thus, the guide tube can more efficiently suppress the expansion of the balloon of the yarn.
In the above guide tube, the second tube part has a bent portion that protrudes outward or inward, and the portion having the non-circular shape of the second tube part is constituted by the bent portion. In this case, in the guide tube, because the impact is applied to the yarn by the portion provided with the bent portion, it is possible to suppress the expansion of the balloon of the yarn.
In the above guide tube, the second tube part has three or more bent portions that protrude outward. Moreover, the portion having the non-circular shape of the second tube part has a regular polygonal shape in which the bent portions and linear portions connecting the bent portions are provided alternately. In this case, in the guide tube, the impact can be efficiently applied on the yarn and the expansion of the balloon of the yarn can be further suppressed.
In the above guide tube, the second tube part has as the bent portion an outwardly bent portion that is the bent portion protruding outward, and an inwardly bent portion that is a bent portion protruding inward, and linear portions connecting the outwardly bent portion and the inwardly bent portion, and the outwardly bent portion is provided in plurality, the inwardly bent portion is provided in the same number as the outwardly bent portion, the outwardly bent portion and the inwardly bent portion are provided alternately in the circumferential direction of the second tube part, and the outwardly bent portions and the inwardly bent portions are connected by the linear portions. In this case, in the guide tube, the impact can be efficiently applied to the yarn by the outwardly bent portions and the inwardly bent portions that are provided alternately.
In the above guide tube, the bent portions provided in the second tube part extend from the second end to the first end thereof and a degree of protrusion of the bent portions gradually decreases as one goes toward the first end. In this case, the second tube part can smoothly guide the yarn toward the first tube part.
In the guide tube, a shape of the first end of the second tube part is circular. In this case, the second tube part can guide the yarn more smoothly toward the first tube part.

According to an aspect of the present invention, expansion of the balloon of the yarn can be efficiently suppressed.
In the above explanation, the meaning of "a plurality of" also includes "a predetermined number of".
Although the invention has been explained with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the scope of the claims.