POT SPINNING METHOD AND POT SPINNING MACHINE

Abstract

 A pot spinning method according to the present invention includes the steps of: forming a cake (28) by rotating a pot (12) having an opening (23) and winding yarn (18) that has been drawn out to a predetermined thickness around an inner wall (22) of the pot (12); disposing a bobbin (25) inside the pot (12) through the opening (23); discharging, to the outside of the pot (12), a portion of the yarn present in a region of the inner wall (22) of the pot (12) that is closer to the opening (23) side than an opening-side end of the cake (28) by blowing compressed air (33) onto the region; and rewinding the yarn (18) forming the cake (28) onto the bobbin (25) from the inner wall (22) of the pot (12) using the yarn portion discharged to the outside of the pot (12) as a rewinding start point.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention relates to a pot spinning method and a pot spinning machine.

2. Description of the Related Art

[0002] A pot spinning method using a cylindrical pot is well known as a spinning method. Patent Document 1 (Japanese Patent Application Publication Laid-open No. H08-325854) describes a technique relating to a pot spinning method and a pot spinning machine. In the technique described in Patent Document 1, a cylindrical bobbin is disposed on the outside of a yarn guide coaxially with the yarn guide, and a cut-out is formed in one end of the bobbin. After forming a cake by winding yarn spun from the yarn guide around an inner wall of the pot while applying twist to the yarn, the yarn is hooked onto the cut-out by causing the end of the bobbin to project in the axial direction, whereby rewinding of the yarn onto the bobbin is started.

SUMMARY OF THE INVENTION

[0003] With the technique described in Patent Document 1, however, the following problems occur.

[0004] The bobbin used in the technique described in Patent Document 1 has a special structure in which one end of the bobbin is formed so as to widen into a skirt-like shape and the cut-out is formed in that end. Moreover, in the technique described in Patent Document 1, a configuration is employed in which the position of the bobbin is maintained by forming a flange on an upper portion of the bobbin and latching latch means to the flange. Hence, the bobbin used in the technique described in Patent Document 1 has a special structure including a flange.

[0005] With the technique described in Patent Document 1, therefore, when a pot spinning machine is newly introduced into an existing spinning factory in which a ring spinning machine is already installed, for example, a specialized bobbin for pot spinning must be prepared separately from the bobbin used for ring spinning. Moreover, a winder and so on for handling the bobbin following removal from the pot spinning machine must be prepared to special specifications in accordance with the structure of the bobbin. As a result, the cost of introducing the pot spinning machine increases.

[0006] The present invention has been devised to solve the problems described above, and an object thereof is to provide a pot spinning method and a pot spinning machine with which rewinding onto a bobbin can be performed appropriately without using a bobbin having a special structure.

[0007] A pot spinning method according to the present invention includes the steps of:

forming a cake by rotating a pot having an opening and a winding yarn that has been drawn out to a predetermined thickness around an inner wall of the pot;

disposing a bobbin inside the pot through the opening;

discharging, to the outside of the pot, a portion of the yarn present in a region of the inner wall of the pot that is closer to the opening side than an opening-side end of the cake by blowing compressed air onto the region; and

rewinding the yarn forming the cake onto the bobbin from the inner wall of the pot using the portion of the yarn discharged to the outside of the pot as a rewinding start point.

[0008] A pot spinning machine according to the present invention includes:

a yarn guide;

a pot having an opening positioned on a side opposite to the yarn guide (11), a part of the yarn guide being inserted into the pot from a side opposite to the opening; and

a bobbin that is disposed to face the yarn guide in a central axis direction of the pot and is inserted into the pot through the opening of the pot,

a cake being formed by winding yarn that has been drawn out to a predetermined thickness around an inner wall of the pot by operating the yarn guide and the pot, and the yarn forming the cake being rewound onto the bobbin from the inner wall of the pot,

wherein the pot spinning machine includes an air nozzle that is inserted into the pot together with the bobbin in order to blow compressed air against the inner wall of the pot, and

the air nozzle blowing compressed air onto a region of the inner wall of the pot that is closer to the opening side than an opening-side end of the cake, whereby a portion of the yarn present in the region is discharged to the outside of the pot.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 

FIG. 1 is a schematic view showing a configurational example of main parts of a pot spinning machine according to an embodiment of the present invention;

FIG. 2 is a partial enlarged view illustrating an arrangement of an air nozzle;

FIG. 3 is a block diagram showing an example configuration of a drive control system of the pot spinning machine according to this embodiment of the present invention;

FIG. 4 is a view showing a basic flow of a pot spinning method;

FIG. 5 is a sectional view illustrating a first state of the pot spinning method according to this embodiment of the present invention;

FIG. 6 is a view illustrating an operation of a yarn guide;

FIG. 7 is a sectional view illustrating a second state of the pot spinning method according to this embodiment of the present invention;

FIG. 8 is a sectional view illustrating a third state of the pot spinning method according to this embodiment of the present invention;

FIG. 9 is a sectional view illustrating a fourth state of the pot spinning method according to this embodiment of the present invention;

FIG. 10 is a sectional view illustrating a fifth state of the pot spinning method according to this embodiment of the present invention;

FIG. 11 is a sectional view illustrating a sixth state of the pot spinning method according to this embodiment of the present invention; and

FIG. 12 is a sectional view illustrating a second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Embodiments of the present invention will be described in detail below with reference to the figures.

Pot Spinning Machine

[0011] First, a pot spinning machine according to an embodiment of the present invention will be described.

[0012] FIG. 1 is a schematic view showing a configurational example of the main parts of the pot spinning machine according to this embodiment of the present invention.

[0013] As shown in FIG. 1, a pot spinning machine 1 includes a drafting device 10, a yarn guide 11, a pot 12, and a bobbin support 13. Note that these constituent elements together constitute a single spindle, which serves as a single spinning unit. The pot spinning machine 1 includes a plurality of spindles, but here, the configuration of one of the plurality of spindles will be described.

(Drafting device)

[0014] The drafting device 10 is a device for drawing out a yarn material such as roving to a predetermined thickness. The drafting device 10 is formed using a plurality of roller pairs constituted by a back roller pair 15, a middle roller pair 16, and a front roller pair 17. The plurality of roller pairs are arranged in order of the back roller pair 15, the middle roller pair 16, and the front roller pair 17 from an upstream side toward a downstream side in a conveyance direction of the yarn material.

[0015] The respective roller pairs 15, 16, 17 rotate when driven by a drafting drive unit, to be described below. When rotation frequencies per unit time (rpm) of the respective roller pairs 15, 16, 17 are compared, the rotation frequency of the middle roller pair 16 is higher than the rotation frequency of the back roller pair 15, and the rotation frequency of the front roller pair 17 is higher than the rotation frequency of the middle roller pair 16. Hence, the respective roller pairs 15, 16, 17 have different rotation frequencies, and using these rotation frequency differences, or in other words rotation speed differences, the drafting device 10 draws the yarn material out thinly. In the following description, the rotation frequencies of the roller pairs will also be referred to as rotation speeds. The rotation frequency and the rotation speed of each roller pair have a mutual corresponding relationship.

(Yarn guide)

[0016] The yarn guide 11 guides yarn 18 drawn out to the predetermined thickness by the drafting device 10 into the pot 12. The yarn guide 11 is formed in the shape of a long, narrow tube. The yarn guide 11 has a circular shape on a cross-section cut in an orthogonal direction to a length direction thereof.

[0017] The yarn guide 11 is disposed coaxially with the pot 12 on the downstream side of the drafting device 10. A lower portion of the yarn guide 11 is inserted into the pot 12. The yarn guide 11 guides the yarn 18, which is supplied from the front roller pair 17 through a yarn supply pipe 14, into the pot 12. The yarn 18 drawn out by the drafting device 10 is pulled into the yarn supply pipe 14 using a swirling flow of air, for example, and then introduced into the yarn guide 11 through the yarn supply pipe 14. The yarn 18 introduced into the yarn guide 11 is spun from a lower end 11a of the yarn guide 11. The yarn guide 11 is provided to be movable in a vertical direction by a yarn guide drive unit, to be described below.

[0018] A yarn sensor 19 is disposed between the front roller pair 17 and the yarn supply pipe 14. The yarn sensor 19 is a sensor for detecting the state of the yarn drawn out by the drafting device 10. In this embodiment, yarn breakage is used as an example of a state of the yarn detected by the yarn sensor 19. Further, in this embodiment, the yarn sensor 19 is formed using an optical sensor combining a light-emitting device 19a and a light-receiving device 19b, for example.

Pot

[0019] The pot 12 is used to form a cake 28 and rewind the yarn. The pot 12 is formed in a cylindrical shape. The pot 12 is provided to be capable of rotating about a central axis K of the pot 12. The central axis K of the pot 12 is disposed parallel to the vertical direction. Accordingly, one side of the central axis direction of the pot 12 is an upward side and the other side is a downward side.

[0020] The pot 12 rotates when driven by a pot driving unit, to be described below. A yarn guide insertion port 21 is formed in an upper end side of the pot 12. The yarn guide insertion port 21 is an opening through which the yarn guide 11 is inserted into the pot 12. An opening 23 is formed in a lower end of the pot 12. The yarn guide insertion port 21 opens upward and has a smaller diameter than a diameter (referred to hereafter as a "pot inner diameter") that defines an inner volume of the pot 12 and is based on the position of an inner wall 22. The opening 23 opens downward and has a diameter identical to the pot inner diameter.

Bobbin Support

[0021] The bobbin support 13 supports the bobbin 25. The bobbin support 13 includes a bobbin base 26 and a bobbin mounting portion 27. The bobbin base 26 is formed in a plate shape. The bobbin mounting portion 27 is fixed to the bobbin base 26. The bobbin mounting portion 27 is formed in a columnar shape and disposed so as to project upward from an upper surface of the bobbin base 26.

[0022] The bobbin mounting portion 27 is a part on which the bobbin 25 is detachably mounted. The bobbin mounting portion 27 is disposed coaxially with the yarn guide 11 and the pot 12 so as to oppose the yarn guide 11 in the central axis direction of the pot 12. Further, the bobbin mounting portion 27 is disposed below the yarn guide 11. Hence, when the bobbin 25 is mounted on the bobbin mounting portion 27, the bobbin 25 is disposed facing the yarn guide 11 on the central axis K of the pot 12.

[0023] The bobbin 25 has a tapered structure such that a bobbin outer peripheral diameter varies continuously from one end side toward the other end side in a bobbin central axis direction. The bobbin 25 corresponds to a general-use bobbin also used in ring spinning and so on. The bobbin 25 has a hollow structure on at least one end side thereof. By fitting the hollow part on one end side of the bobbin 25 to the bobbin mounting portion 27, the bobbin 25 is supported so as to stand vertically upright from the bobbin base 26.

[0024] The bobbin support 13 is provided to be movable in the vertical direction by a bobbin drive unit, to be described below. The outer peripheral diameter of the bobbin 25 is set to be smaller than the minimum diameter of the cake 28 formed on the inner wall 22 of the pot 12. Thus, contact between the bobbin 25 and the cake 28 can be avoided when the bobbin 25 is inserted into the pot 12 through the opening 23 in the pot 12 and disposed therein.

Air Nozzle

[0025] The pot spinning machine 1 according to this embodiment of the present invention includes an air nozzle 31 in addition to the constituent elements described above. The air nozzle 31 blows compressed air onto a region 22a closer to the opening 23 side than a winding end-side end 28b of the cake 28, which is formed on the inner wall 22 of the pot 12 by the operations of the yarn guide 11 and the pot 12. By blowing compressed air, the air nozzle 31 discharges to the outside of the pot 12 a portion of the yarn that is wound in the region 22a of the pot 12 and serves as a rewinding start point for rewinding the yarn onto the bobbin 25.

[0026] The rewinding start point is the part of the yarn that is wound onto the bobbin 25 first when the yarn forming the cake 28 is rewound onto the bobbin 25. Accordingly, rewinding onto the bobbin 25 starts when the portion of the yarn serving as the rewinding start point is wound onto the bobbin 25. In this embodiment, of the yarn wound around the inner wall 22 of the pot 12, the part of the yarn that is wound between the winding end-side end of the cake 28 and the opening 23 in the central axis direction of the pot 12 serves as the rewinding start point. Further, when seen in the central axis direction of the pot 12, the winding end-side end of the cake 28 corresponds to the opening 23 side end of the cake 28.

[0027] The air nozzle 31 is provided on the bobbin support 13. The air nozzle 31 is attached to the bobbin base 26. The air nozzle 31 is disposed near the bobbin mounting portion 27 so as to stand vertically upright from the bobbin base 26.

[0028] The air nozzle 31 includes an ejection port 32 for ejecting the compressed air. The ejection port 32 of the air nozzle 31 is disposed near the upper end of the air nozzle 31. The compressed air ejected through the ejection port 32 of the air nozzle 31 is blown diagonally onto the inner wall 22 of the pot 12 toward the opening 23 side of the pot 12 in response to driving operations performed by the bobbin drive unit and an air nozzle drive unit, to be described below.

[0029] Here, as shown in FIG. 2, when compressed air 33 is blown onto the inner wall 22 of the pot 12 through the air nozzle 31, a blowing angle θ at which the compressed air 33 is blown onto the inner wall 22 of the pot 12 has a predetermined angle of incline toward the opening 23 side. The blowing angle θ of the compressed air 33 is preferably no less than 20 degrees and no more than 60 degrees, and more preferably no less than 30 degrees and no more than 45 degrees. By setting the blowing angle θ of the compressed air 33 thus, a suitable distance L for blowing the compressed air 33 is secured easily between the inner wall 22 of the pot 12 and the air nozzle 31.

[0030] FIG. 3 is a block diagram showing a configurational example of a drive control system of the pot spinning machine according to this embodiment of the present invention.

[0031] As shown in FIG. 3, the pot spinning machine 1 includes a control unit 51, a drafting drive unit 52, a yarn guide drive unit 53, a pot drive unit 54, a bobbin drive unit 55, and a nozzle drive unit 56.

Control Unit

[0032] The control unit 51 performs overall control of all of the operations of the pot spinning machine 1. The drafting drive unit 52, the yarn guide drive unit 53, the pot drive unit 54, the bobbin drive unit 55, and the nozzle drive unit 56 are electrically connected to the control unit 51 as operational control objects. The yarn sensor 19 is also electrically connected to the control unit 51. When yarn breakage occurs in the drafting device 10, the yarn sensor 19 outputs a yarn breakage occurrence signal informing the control unit 51of the yarn breakage.

Drafting Drive Unit

[0033] The drafting drive unit 52 rotates the back roller pair 15, the middle roller pair 16, and the front roller pair 17 at the respective predetermined rotation frequencies thereof. The drafting drive unit 52 rotates the back roller pair 15, the middle roller pair 16, and the front roller pair 17 by implementing driving on the basis of a drafting drive signal applied to the drafting drive unit 52 from the control unit 51.

Yarn Guide Drive Unit

[0034] The yarn guide drive unit 53 operates the yarn guide 11. The yarn guide drive unit 53 operates the yarn guide 11 to move in the vertical direction. The yarn guide drive unit 53 moves the yarn guide 11 in the vertical direction by implementing driving on the basis of a yarn guide drive signal applied to the yarn guide drive unit 53 from the control unit 51.

Pot Drive Unit

[0035] The pot drive unit 54 rotates the pot 12. The pot drive unit 54 rotates the pot 12 using the central axis K of the pot 12 as a rotational center by implementing driving on the basis of a pot drive signal applied thereto from the control unit 51.

Bobbin Drive Unit

[0036] The bobbin drive unit 55 operates the bobbin 25. The bobbin drive unit 55 operates the bobbin 25 mounted on the bobbin mounting portion 27 of the bobbin support 13 to move in the vertical direction integrally with the bobbin support 13 and the air nozzle 31. The bobbin drive unit 55 moves the bobbin 25 in the vertical direction by implementing driving on the basis of a bobbin drive signal applied thereto from the control unit 51.

Nozzle Drive Unit

[0037] The nozzle drive unit 56 operates the air nozzle 31. The nozzle drive unit 56 operates the air nozzle 31 so that compressed air is ejected through the ejection port 32 in the air nozzle 31. The nozzle drive unit 56 causes the air nozzle 31 to eject compressed air by implementing driving on the basis of a nozzle drive signal applied thereto from the control unit 51.

Pot Spinning Method

[0038] Next, a pot spinning method according to this embodiment of the present invention will be described.

[0039] FIG. 4 is a view showing a basic flow of the pot spinning method.

[0040] As shown in FIG. 4, the pot spinning method includes a drawing-out step S1, a cake-forming step S2, and a rewinding step S3.

[0041] The drawing-out step S1 is a step for drawing out a yarn material such as roving to a predetermined thickness. The cake-forming step S2 is a step for forming the cake 28 by winding the yarn drawn out to the predetermined thickness in the drawing-out step S1 around the inner wall 22 of the pot 12. The rewinding step S3 is a step for rewinding the yarn forming the cake 28 onto the bobbin 25. Operations of the pot spinning machine 1 based on the respective steps will be described below.

[0042] It is assumed that before the pot spinning machine 1 is operated, the yarn guide 11 has been disposed near the yarn supply pipe 14, the bobbin 25 has been mounted on the bobbin mounting portion 27 of the bobbin support 13, and the bobbin 25 has been disposed below and away from the pot 12.

Drawing-out Step

[0043] The drawing-out step S1 is performed using the drafting device 10. The drafting drive unit 52 rotates the back roller pair 15, the middle roller pair 16, and the front roller pair 17 at the respective predetermined rotation speeds thereof by implementing driving on the basis of the drafting drive signal applied thereto from the control unit 51. As a result, the yarn material, such as roving, is conveyed by the rotation of the respective roller pairs 15, 16, 17.

[0044] At this time, the control unit 51 sets the rotation speed of the back roller pair 15 at a lower speed than the rotation speed of the middle roller pair 16 and sets the rotation speed of the middle roller pair 16 at a lower speed than the rotation speed of the front roller pair 17. Accordingly, the yarn is drawn out between the back roller pair 15 and the middle roller pair 16 by the rotation speed difference between these roller pairs. Similarly, the yarn is drawn out between the middle roller pair 16 and the front roller pair 17 by the rotation speed difference between these roller pairs.

[0045] As a result, the yarn material, such as roving, is drawn out to the predetermined thickness while passing in order through the back roller pair 15, the middle roller pair 16, and the front roller pair 17. The yarn 18 drawn out in this manner is then pulled into the yarn supply pipe 14 using a swirling flow of air and then introduced into the yarn guide 11.

[0046] Further, before the start of the drawing-out step S1, the control unit 51 applies the pot driving signal to the pot drive unit 54 to rotate the pot 12 at a predetermined rotation frequency.

Cake-forming Step

[0047] The cake-forming step S2 is performed using the yarn guide 11 and the pot 12. The yarn guide drive unit 53 moves the yarn guide 11 by a predetermined amount downward by implementing driving on the basis of the yarn guide drive signal applied thereto from the control unit 51. Further, the pot drive unit 54 continues to rotate the pot 12 by implementing driving on the basis of the pot drive signal applied thereto from the control unit 51. Note that when the yarn guide 11 is moved downward, the yarn guide 11 is in a positionremoved from the yarn supply pipe 14. Further, the yarn 18 introduced into the yarn guide 11 from the yarn supply pipe 14 is spun from the lower end 11a of the yarn guide 11.

[0048] Centrifugal force generated by the rotation of the pot 12 acts on the yarn 18 spun from the lower end 11a of the yarn guide 11, and as a result of this centrifugal force, the yarn 18 is pressed against the inner wall 22 of the pot 12. Further, the yarn 18 pressed against the inner wall 22 of the pot 12 is twisted by the rotation of the pot 12. As a result, the yarn 18 spun from the lower end 11a of the yarn guide 11 is wound around the inner wall 22 of the pot 12 in a state where twist is applied thereto by the rotation of the pot 12.

[0049] Furthermore, as shown in FIG. 5, by implementing driving on the basis of the yarn guide drive signal, the yarn guide drive unit 53 displaces the position of the yarn guide 11 relatively downward while moving the yarn guide 11 in a vertical reciprocating motion repeatedly at predetermined intervals. As a result, the cake 28 is formed on the inner wall 22 of the pot 12. The cake 28 is a laminated body formed from the yarn 18 wound around the inner wall 22 of the pot 12.

[0050] FIG. 6 is a view illustrating the operation of the yarn guide during the cake-forming step. The vertical axis of the figure shows the position of the yarn guide in the pot central axis direction, and the horizontal axis shows time.

[0051] In FIG. 6, first, the yarn guide 11 descends to a P1 position, then ascends to a P2 position, then descends to a P3 position, and then ascends to a P4 position. In other words, the yarn guide 11 repeatedly performs a vertical reciprocating motion. In this case, a period T1 from the point at which the yarn guide 11 reaches the P1 position to the point at which the yarn guide 11 reaches the P3 position and a period T2 from the point at which the yarn guide 11 reaches the P2 position to the point at which the yarn guide 11 reaches the P4 position each serve as one period. Further, to displace the position of the yarn guide 11 relatively downward, the P3 position is set to be lower than the P1 position and the P4 position is set to be lower than the P2 position. A vertical deviation H1 between the P1 position and the P3 position and a vertical deviation H2 between the P2 position and the P4 position each serve as a displacement step amount of the yarn guide 11 during one period. In other words, the yarn guide 11 is displaced downward by one fixed displacement step amount at a time while performing a vertical reciprocating motion repeatedly at fixed period intervals. This operation of the yarn guide 11 continues until the yarn guide 11 reaches a Pm position. In this case, the P1 position defines a winding start-side end 28a of the cake 28, shown in FIG. 1, and the Pm position defines a winding end-side end 28b of the cake 28, shown in the same figure.

[0052] The control unit 51 operates the yarn guide 11, as shown in FIGS. 5 and 6, by applying the yarn guide drive signal to the yarn guide drive unit 53. As a result, the cake 28 is formed on the inner wall 22 of the pot 12 in the shape shown in FIG. 5. In this embodiment, the following step is further included after the cake 28 is formed by the operation of the yarn guide 11 in the cake-forming step S2.

[0053] After the yarn guide 11 reaches the Pm position, the control unit 51 moves the yarn guide 11 downward by a predetermined amount Lh. As a result, as shown in FIG. 7, the portion of the yarn 18a that serves as the rewinding start point for rewinding the yarn onto the bobbin 25 is wound around the inner wall 22 of the pot 12 in the region 22a closer to the opening 23 side than the terminal end 28b of the cake 28. The portion of the yarn 18a may be wound in a single layer or a plurality of layers. When the portion of the yarn 18a is wound in a single layer, yarn cutting may be performed at a stage where the yarn guide 11 is lowered from the Pm position to a Pn position. Further, when the portion of the yarn 18a is wound in a plurality of layers, yarn cutting may be performed at a stage where an operation for lowering the yarn guide 11 from the Pm position to the Pn position and then raising the yarn guide 11 to a higher position than the Pn position has been performed at least once. Note that the predetermined amount Lh is preferably no less than 3 mm and no more than 7 mm.

[0054] Here, the difference between "yarn cutting" and "yarn breakage" will be described.

[0055] Yarn cutting is performed intentionally at the stage where the yarn 18 is wound around the inner wall 22 of the pot 12 in a predetermined amount set in advance. Yarn breakage, on the other hand, is a phenomenon whereby the yarn 18 breaks for one of various reasons before being wound around the inner wall 22 of the pot 12 in the predetermined amount.

[0056] Yarn cutting is performed under the control of the control unit 51. More specifically, the control unit 51 controls the driving implemented by the drafting drive unit 52 so that rotation of both the back roller pair 15 and the middle roller pair 16 is stopped while the front roller pair 17 continue to rotate. As a result, the yarn 18 is forcibly cut on the downstream side of the middle roller pair 16.

[0057] Further, the control unit 51 modifies the spinning conditions during yarn cutting so that the yarn strength of the portion of the yarn 18a that serves as the rewinding start point for rewinding the yarn onto the bobbin 25 is greater than the yarn strength of the portion of the yarn forming the cake 28. In this case, the control unit 51 corresponds to a spinning condition modification unit. The yarn strength increases steadily as the thickness of the yarn increases. The yarn strength also increases steadily as the number of twists in the yarn increases. One or a plurality of spinning conditions may be modified to increase the yarn strength. In this embodiment, the rotation speed of the front roller pair 17 is used as an example of the spinning condition to be modified. When the rotation speed of the front roller pair 17 is modified, the rotation speed difference between the middle roller pair 16 and the front roller pair 17 varies accordingly.

[0058] Hence, the control unit 51 reduces the rotation speed of the front roller pair 17 so as to increase the strength of the portion of the yarn 18a that serves as the rewinding start point, as described above. When the rotation speed of the front roller pair 17 is reduced, the rotation speed difference between the middle roller pair 16 and the front roller pair 17 decreases. Moreover, the speed at which the yarn is fed from the front roller pair 17 decreases, leading to an increase in the number of twists. As a result, the thickness of the yarn 18 drawn out by the drafting device 10 increases. Hence, the yarn strength of the portion of the yarn 18a that serves as the rewinding start point can be increased by reducing the rotation speed of the front roller pair 17 when the yarn 18 to be wound around the region 22a of the inner wall 22 of the pot 12 passes through the drafting device 10.

[0059] The cake-forming step S2 ends when cake formation and yarn cutting, as described above, are completed and a yarn end formed by the yarn cutting is wound around the inner wall 22 of the pot 12.

Rewinding Step

[0060] The rewinding step S3 is performed using the pot 12, the bobbin 25, and the air nozzle 31. In the rewinding step S3, the bobbin 25 and the air nozzle 31 are disposed inside the pot 12 through the opening 23 by the driving implemented by the pot drive unit 54. The pot drive unit 54 continues to rotate the pot 12 by implementing driving on the basis of the pot drive signal applied thereto from the control unit 51. As shown in FIG. 9, the bobbin drive unit 55 moves the bobbin support 13 upward by implementing driving on the basis of the bobbin drive signal applied thereto from the control unit 51. As a result, the bobbin 25 mounted on the bobbin mounting portion 27 (see FIG. 1) and the air nozzle 31 attached to the bobbin base 26 both move upward. Further, the bobbin 25 and the air nozzle 31 enter the pot 12 through the opening 23 in the pot 12. At this time, the ejection port 32 of the air nozzle 31 is disposed in a diagonally downward orientation toward the inner wall 22 of the pot 12. Meanwhile, as shown in FIG. 9, the yarn guide drive unit 53 moves the yarn guide 11 upward by implementing driving on the basis of the yarn guide drive signal applied thereto from the control unit 51. As a result, before the bobbin 25 enters the pot 12, the lower end 11a of the yarn guide 11 retreats to a position inside the pot 12 where the yarn guide 11 does not contact the bobbin 25.

[0061] Next, as shown in FIG. 10, the control unit 51 applies the nozzle drive signal to the nozzle drive unit 56 so that the compressed air 33 is ejected through the ejection port 32 in the air nozzle 31. The ejection time of the compressed air 33 is to be set within a range of no less than 0.2 seconds and no more than 2 seconds, for example. As a result, the compressed air 33 ejected through the ejection port 32 in the air nozzle 31 is blown toward the inner wall 22 of the pot 12. The blowing angle θ (see FIG. 2) of the compressed air 33 is preferably set at no less than 20 degrees and no more than 60 degrees, and more preferably no less than 40 degrees and no more than 50 degrees, toward the opening 23 side relative to the inner wall 22 of the pot 12. The compressed air 33 ejected by the air nozzle 31 is blown onto the yarn portion wound closer to the opening 23 side than the terminal end 28b of the cake 28, or in other words the portion of the yarn 18a that serves as the rewinding start point for rewinding the yarn onto the bobbin 25. As a result, the portion of the yarn 18a is pushed out of the pot 12 by the compressed air 33 so as to be discharged through the opening 23 in the pot 12.

[0062] While the compressed air 33 is being blown, the control unit 51 controls the driving implemented by the pot drive unit 54 so as to relatively reduce the rotation frequency of the pot 12. More specifically, the rotation frequency of the pot 12 during formation of the cake 28 is set as a first rotation frequency (rpm), and the rotation frequency of the pot 12 during blowing of the compressed air is set as a second rotation frequency (rpm). In this case, the control unit 51 controls the driving implemented by the pot drive unit 54 so that the second rotation frequency falls below the first rotation frequency. Here, when the first rotation frequency is set as A (rpm) and the second rotation frequency is set as B (rpm), the control unit 51 preferably controls the driving implemented by the pot drive unit 54 so that the condition "0.6 A ≤ B ≤ 0.8 A" is satisfied.

[0063] By controlling the rotation frequency of the pot 12 in this manner, while the compressed air is blown, the force for pressing the yarn against the inner wall 22 of the pot 12, or in other words the centrifugal force, weakens. Accordingly, when the compressed air 33 is blown from the air nozzle 31, the yarn portion 18a can be more easily peeled away from the inner wall 22 of the pot 12. In comparison with a case where the rotation frequency of the pot 12 is not reduced, therefore, the portion of the yarn 18a can be discharged to the outside of the pot 12 with less force. Moreover, by reducing the rotation frequency of the pot 12, tension acting on the yarn is reduced. Thus, the yarn portion 18a discharged to the outside of the pot 12 by the compressed air 33 blown thereon is less likely to break, and as a result, the risk of failure during rewinding due to yarn breakage can be reduced.

[0064] When the yarn portion 18a that serves as the rewinding start point for rewinding the yarn onto the bobbin 25 is discharged to the outside of the pot 12, as described above, the yarn portion 18a discharged to the outside of the pot 12 cannot rotate integrally with the pot 12 and is therefore rotated with a delay by the rotation of the pot 12. As a result, the yarn portion 18a starts to be wound onto the bobbin 25 disposed on the central axis K of the pot 12. Thus, rewinding onto the bobbin 25 can be started using the yarn portion 18a discharged inside the pot 12 as the rewinding start point.

[0065] Subsequently, when all of the yarn forming the cake 28 has been rewound onto the bobbin 25, as shown in FIG. 11, the control unit 51 moves the bobbin support 13 downward by applying the bobbin drive signal to the bobbin drive unit 55. As a result, the rewinding step S3 is complete.

[0066] As a result of the operation described above, the bobbin 25 is obtained with a yarn tube 29 wound thereon. The bobbin 25 with the yarn tube 29 wound thereon is removed from the bobbin mounting portion 27. An empty bobbin 25 is then mounted on the bobbin mounting portion 27, whereupon a similar operation to that described above is performed.

Effects of Embodiment

[0067] This embodiment of the present invention employs a configuration in which the air nozzle 31 is provided in the pot spinning machine 1. Further, the pot spinning method employs a configuration in which the yarn is rewound onto the bobbin 25 by blowing compressed air using the air nozzle 31 onto the yarn portion 18a that serves as the rewinding start point for rewinding the yarn onto the bobbin 25, which is wound around the region 22a of the inner wall 22 of the pot 12, in order to discharge the yarn portion 18a to the outside of the pot 12. Thus, rewinding onto the bobbin 25 can be appropriately performed without using a bobbin having a special structure. Therefore, when a pot spinning machine is newly introduced into an existing spinning factory in which a ring spinning machine is already installed, for example, the bobbin used for ring spinning can be used as is for pot spinning. As a result, the cost involved in introducing the pot spinning machine can be reduced. Moreover, in the prior art, the bobbin is mounted on the outside of the yarn guide, making it necessary to increase the diameter of the upper opening in the pot and the diameter of a bearing for supporting the pot, and as a result, problems occur in terms of the life of the bearing, power consumption, and cost. With this embodiment, these problems do not occur.

[0068] Furthermore, according to this embodiment of the present invention, with respect to the cake 28 formed on the inner wall 22 of the pot 12, a non-contact method in which compressed air is blown onto the cake 28 is employed instead of a contact method in which a member physically contacts the cake 28. As a result, rewinding onto the bobbin 25 can be performed without causing any of the various problems that may arise with a contact method. Note that the problems that may arise with a contact method include, for example, a reduction in durability due to wear on the member, a reduction in the quality of the yarn tube due to intermixing of wear particles, and so on.

[0069] Moreover, according to this embodiment of the present invention, when yarn breakage occurs midway through the cake-forming step S2, more response time for dealing with an abnormal spindle can be secured than with the technique described in Patent Document 1. The reason for this is as follows.

[0070] First, in the technique described in Patent Document 1, when a cake is formed by winding yarn around the inner wall of the pot, yarn cutting is performed by causing one end of the bobbin to project in the axial direction while continuing to spin the yarn from the lower end of the yarn guide so that the yarn is hooked onto the cut-out in the bobbin. Therefore, if the end of the bobbin is not caused to project at a timing (referred to hereafter as a "full pot timing") when a predetermined amount of the yarn is wound around the inner wall of the pot, surplus yarn exceeding the predetermined amount is wound, leading to a reduction in the inner diameter of the cake. Hence, when the bobbin is caused to project, the bobbin may contact the cake rotating together with the pot, and as a result, various problems, for example breakage of the bobbin, inappropriate rewinding onto the bobbin, and so on, may occur. With the technique described in Patent Document 1, therefore, the bobbin must be caused to project while continuing to spin the yarn at the full pot timing in order to start rewinding onto the bobbin.

[0071] In this embodiment of the present invention, meanwhile, yarn cutting is performed by having the control unit 51 control the drafting device 10 at the stage where a predetermined amount of the yarn 18 is wound around the inner wall 22 of the pot 12, and thereafter, rewinding onto the bobbin 25 does not start until the compressed air is ejected from the air nozzle 31. This means that rewinding onto the bobbin 25 can be started at any desired timing after the yarn 18 has been wound around the inner wall 22 of the pot 12 in the predetermined amount. With the technique described in Patent Document 1, on the other hand, the timing at which to start rewinding onto the bobbin cannot be chosen as desired and is limited to an extremely narrow range.

[0072] Hence, according to this embodiment of the present invention, when yarn breakage occurs midway through the cake-forming step S2, rewinding onto the bobbin 25 can be put on standby until the abnormal spindle has been dealt with, even if the timing at which yarn breakage occurs is immediately before the full pot timing, for example. More specifically, the ejection timing of the compressed air can be delayed by the amount of time needed to deal with the abnormal spindle. Therefore, even when yarn breakage occurs immediately before the full pot timing, sufficient time for dealing with the yarn breakage can be secured. With regard to this point, in the technique described in Patent Document 1, rewinding onto the bobbin must be started substantially simultaneously with the full pot timing, and therefore, when yarn breakage occurs immediately before the full pot timing, sufficient time for dealing with the yarn breakage cannot be secured.

[0073] Incidentally, the time required to respond to yarn breakage is as follows, for example.

[0074] When yarn breakage occurs midway through the cake-forming step S2, the yarn sensor 19 outputs a yarn breakage occurrence signal, and the control unit 51, upon reception of the yarn breakage occurrence signal, specifies the spindle to which the yarn sensor 19 that output the yarn breakage occurrence signal belongs. Further, the control unit 51 moves a self-propelled wagon (not shown) provided in the pot spinning machine 1 to the position of the specified spindle. The wagon includes an elevating machine for raising the air nozzle provided in each spindle so that rewinding onto the bobbin 25 is started in the spindle where the yarn breakage has occurred at a similar timing to the other spindles. Therefore, every time yarn breakage occurs in one of the spindles, time for moving the wagon and operating the elevating machine is required, and this time is the time required to respond to yarn breakage.

[0075] Furthermore, this embodiment of the present invention employs a configuration in which the spinning conditions are modified at the time of yarn cutting so that the yarn strength of the portion of the yarn 18a that serves as the rewinding start point is greater than the yarn strength of the yarn portion forming the cake 28. Thus, the portion of the yarn 18a discharged to the outside of the pot 12 by the compressed air blown thereon is less likely to break than when the spinning conditions are not modified at the time of yarn cutting. Accordingly, the portion of the yarn 18a discharged to the outside of the pot 12 can be wound around the bobbin 25 more reliably, and as a result, the risk of failure during rewinding onto the bobbin 25 can be reduced.

[0076] However, when yarn breakage occurs midway through cake formation, cake formation is substantially completed at the stage where the end of the yarn 18 that is generated by the yarn breakage is wound around the inner wall 22 of the pot 12. Accordingly, the position in which the end of the yarn 18 that is generated by the yarn breakage is wound (referred to hereafter as the "yarn breakage position") deviates upward relative to the corresponding position in a case where yarn cutting is performed after cake formation is completed normally. In this case, the distance from the yarn breakage position to the opening 23 of the pot 12 increases. Therefore, with a configuration in which compressed air is blown using the air nozzle 31, it becomes more difficult to discharge the end of the broken yarn 18 to the outside of the pot 12.

Second Embodiment

[0077] Therefore, in a second embodiment of the present invention, a configuration shown in FIG. 12 is employed.

[0078] In FIG. 12, an air nozzle 61 is attached to the bobbin base 26 of the bobbin support 13. The air nozzle 61 can be raised and lowered by elevating means, not shown in the figure, in accordance with the height of the yarn breakage position. A plurality of ejection ports 62 are provided in the air nozzle 61. The plurality of ejection ports 62 respectively eject compressed air. The plurality of ejection ports 62 are provided at intervals in the vertical direction serving as the central axis direction of the pot 12. The compressed air ejected through the respective ejection ports 62 is blown diagonally onto the inner wall 22 of the pot 12 toward the opening 23 side of the pot 12. Further, the air nozzle 61 is disposed so that the compressed air ejected from the ejection port 62 on the side furthest from the opening 23 of the pot 12, among the plurality of ejection ports 62, is blown onto the end of the yarn 18 that is generated by the yarn breakage, or in other words the yarn breakage position. The yarn breakage position of the cake 28 corresponds to the opening 23 side end of the cake 28 when seen in the central axis direction of the pot 12. Similarly to the above embodiment, the angle at which the compressed air is blown onto the inner wall 22 of the pot 12 is preferably no less than 20 degrees and no more than 60 degrees, and more preferably no less than 30 degrees and no more than 45 degrees. The direction in which the compressed air is blown relative to an inner peripheral direction of the pot 12 may be set as a parallel direction to a normal direction perpendicular to the inner peripheral direction of the pot 12, for example. This point is similar to the first embodiment.

[0079] In the second embodiment of the present invention, when yarn breakage occurs midway through cake formation during the cake-forming step S2, the control unit 51 specifies the yarn breakage position on the cake on the basis of the yarn breakage occurrence signal output from the yarn sensor 19. Next, in the rewinding step S3, the control unit 51 disposes the bobbin 25 and the air nozzle 61 inside the pot 12 through the opening 23 by raising the bobbin base 26, and then uses the air nozzle 61 to blow compressed air onto the inner wall 22 of the pot 12 in a range extending from the specified yarn breakage position to the opening 23.

[0080] Compressed air is blown using the air nozzle 61 by having the control unit 51 output a nozzle drive signal to the nozzle drive unit 56. As a result, compressed air is blown onto the inner wall 22 of the pot 12 in a range extending from the yarn breakage position to the opening 23 in a plurality of locations at intervals in the central axis direction of the pot 12. At this time, by blowing the compressed air ejected through the uppermost ejection port 62 toward the yarn breakage position, the yarn can be peeled away from the inner wall 22 of the pot 12 in the yarn breakage position. Moreover, the yarn peeled away from the inner wall 22 of the pot 12 can be moved to the opening 23 side by the compressed air blown thereon from the ejection ports 62 positioned below the uppermost ejection port 62, whereby the yarn can be discharged to the outside of the pot 12. Hence, even when yarn breakage occurs midway during cake formation, the yarn can be rewound onto the bobbin 25 from the inner wall 22 of the pot 12 by blowing compressed air through the air nozzle 61.

[0081] Note that the air nozzle 61 is not limited to a case in which yarn breakage occurs midway during cake formation and may also be applied to rewinding following the normal completion of cake formation. In this case, to ensure that the compressed air ejected through the plurality of ejection ports 62 is not blown directly onto the cake 28, a configuration in which a nozzle position adjustment mechanism for adjusting the position of the air nozzle 61 in the central axis direction of the pot 12 is provided and driving of the nozzle position adjustment mechanism is controlled by the control unit 51 may be employed. Further, as regards the position of the air nozzle 61, a configuration in which the control unit 51 specifies the yarn breakage position on the basis of the timing at which the yarn breakage occurrence signal is output from the yarn sensor 19 and controls driving of the nozzle position adjustment mechanism in accordance with the specified yarn breakage position may be employed.

[0082] Furthermore, the nozzle position adjustment mechanism is not limited to a configuration in which the air nozzle 61 is provided and may also be applied to a configuration in which the air nozzle 31, described above, is provided. By employing this configuration, when the terminal end position of the cake 28 is modified in the central axis direction of the pot 12, the air nozzle 31 can be disposed in an appropriate position corresponding to the modified terminal end position of the cake 28.

Modified Examples etc.

[0083] The technical scope of the present invention is not limited to the embodiments described above, and also includes embodiments obtained by applying various modifications and amendments within a scope in which the specific effects obtained by the constituent elements of the invention and combinations thereof can be derived.

[0084] For example, in the above embodiments, examples in which the yarn guide 11 is disposed relatively upward and the bobbin 25 is disposed relatively downward were described as the configuration of the pot spinning machine 1, but the present invention is not limited thereto, and instead, the yarn guide 11 may be disposed relatively downward and the bobbin 25 may be disposed relatively upward. Further, the central axis K of the pot 12 (see FIG. 1) does not necessarily have to be parallel to the vertical direction. For example, the central axis K of the pot 12 may be disposed at an incline relative to the vertical direction or perpendicular to the vertical direction.

[0085] Furthermore, in the above embodiments, a configuration in which the air nozzle 31 is attached to the bobbin base 26 of the bobbin support 13 so that the air nozzle 31 moves in the vertical direction integrally with the bobbin support 13 was described, but the present invention is not limited thereto, and instead, for example, a configuration in which the air nozzle 31 is capable of moving in the vertical direction separately from the bobbin support 13 may be employed. This point applies similarly to the air nozzle 61 described as the second embodiment.

[0086] Further, in the above embodiments, as the operation of the yarn guide 11 for forming the cake 28, as shown in FIG. 6, the yarn guide 11 is operated to descend continuously from the Pm-1 position through the Pm position to the Pn position, but the present invention is not limited thereto, and instead, for example, the operation for lowering the yarn guide 11 may be stopped temporarily at the stage where the yarn guide 11 reaches the Pm position from the Pm-1 position, and the yarn guide 11 may be lowered to the Pn position thereafter. Also, in FIG. 6, the speed at which the yarn guide 11 descends when lowered from the Pm-1 position to the Pm position and the speed at which the yarn guide 11 descends when lowered from the Pm position to the Pn position are identical, but the present invention is not limited thereto, and the operations for lowering the yarn guide 11 may be performed at different speeds. More specifically, the speed at which the yarn guide 11 descends when lowered from the Pm position to the Pn position may be made either higher or lower than the speed at which the yarn guide 11 descends when lowered from the Pm-1 position to the Pm position.

[0087] Furthermore, in the above embodiments, the bobbin 25 that can be applied to ring spinning is used, but the present invention may be implemented using a different bobbin.

[0088] Moreover, in the above embodiments, the yarn portion 18a that serves as the rewinding start point for rewinding the yarn onto the bobbin 25 is wound around the region 22a on the opening 23 side of the terminal end 28b of the cake 28 by moving the yarn guide 11 downward by the predetermined amount Lh after the yarn guide 11 reaches the Pm position, but depending on the type of yarn, the yarn inside the yarn guide 11 following yarn cutting may be wound in several layers in the region 22a so as to form the portion of the yarn 18a that serves as the rewinding start point. In this case, following yarn cutting, the step for discharging the portion of the yarn 18a to the outside of the pot using compressed air can be implemented without moving the yarn guide 11 downward from the Pm position by the predetermined amount.

[0089] Furthermore, a different cake-forming step (a step such as that disclosed in Japanese Patent Application Publication Laid-open No. H04-308227, for example) to the cake-forming step shown in FIG. 6 may be performed.

[0090] Moreover, the opening of the pot may be on the upper side.

[0091] A pot spinning method according to the present invention includes the steps of: forming a cake by rotating a pot having an opening and winding yarn that has been drawn out to a predetermined thickness around an inner wall of the pot; disposing a bobbin inside the pot through the opening; discharging, to the outside of the pot, a portion of the yarn present in a region of the inner wall of the pot that is closer to the opening side than an opening-side end of the cake by blowing compressed air onto the region; and rewinding the yarn forming the cake onto the bobbin from the inner wall of the pot using the yarn portion discharged to the outside of the pot as a rewinding start point.

Claims

1. A pot spinning method comprising the steps of:

forming a cake (28) by rotating a pot (12) having an opening (23) and a winding yarn (18) that has been drawn out to a predetermined thickness around an inner wall (22) of the pot (12);

disposing a bobbin (25) inside the pot (12) through the opening (23);

discharging, to the outside of the pot (12), a portion of the yarn present in a region of the inner wall (22) of the pot (12) that is closer to the opening (23) side than an end of the cake (28) on the opening (23) side by blowing compressed air (33) onto the region; and

rewinding the yarn (18) forming the cake (28) onto the bobbin (25) from the inner wall (22) of the pot (12) using the portion of the yarn discharged to the outside of the pot (12) as a rewinding start point.

2. The pot spinning method according to claim 1, wherein the pot (12) is rotated at a first rotation frequency when forming the cake (28) and at a second rotation frequency, which is lower than the first rotation frequency, when blowing the compressed air (33).

3. The pot spinning method according to claim 1 or 2, wherein a blowing angle (θ) at which the compressed air (33) is blown is no less than 20 degrees and no more than 60 degrees toward the opening (23) side relative to the inner wall (22) of the pot (12).

4. The pot spinning method according to any one of claims 1 to 3, comprising the step of winding the portion of the yarn that serves as the rewinding start point (25) in a region of the inner wall (22) of the pot (12) that is closer to the opening (23) side than a winding end-side end (28b) of the cake (28).

5. The pot spinning method according to any one of claims 1 to 4, wherein the yarn strength of the portion of the yarn that serves as the rewinding start point is greater than the yarn strength of a portion of the yarn forming the cake (28).

6. The pot spinning method according to any one of claims 1 to 5, wherein, when yarn breakage occurs during formation of the cake (28), the portion of the yarn that is formed by winding the yarn (18) extending from a yarn breakage location to the cake (28) in the region is discharged to the outside of the pot (12) by blowing the compressed air (33) in a plurality of locations set at intervals in a central axis direction of the pot (12) onto the inner wall (22) of the pot (12) from the portion of the yarn up to the opening (23).

7. A pot spinning machine comprising:

a yarn guide (11);

a pot (12) having an opening (23) positioned on a side opposite to the yarn guide (11), a part of the yarn guide (11) being inserted into the pot (12) from a side opposite to the opening (23); and

a bobbin (25) that is disposed to face the yarn guide (11) in a central axis direction of the pot (12) and is inserted into the pot (12) through the opening (23) of the pot (12),

a cake (28) being formed by winding yarn (18) that has been drawn out to a predetermined thickness around an inner wall (22) of the pot (12) by operating the yarn guide (11) and the pot (12), and the yarn (18) forming the cake (28) being rewound onto the bobbin (25) from the inner wall (22) of the pot (12),

wherein the pot spinning machine includes an air nozzle (31) that is inserted into the pot (12) together with the bobbin (25) in order to blow compressed air (33) against the inner wall (22) of the pot (12), and

the air nozzle (31) blowing the compressed air (33) onto a region of the inner wall (22) of the pot (12) that is closer to the opening (23) side than an end of the cake (28) on the opening (23) side, whereby a portion of the yarn present in the region is discharged to the outside of the pot (12).

Drawing