EP1717182A2

EP1717182A2 - Yarn slack eliminating device in textile machine

Info

Publication number: EP1717182A2
Application number: EP06003997A
Authority: EP
Inventors: Kenichi Ueda; Hiroyuki Yagi
Original assignee: Murata Machinery Ltd
Current assignee: Murata Machinery Ltd
Priority date: 2005-04-28
Filing date: 2006-02-27
Publication date: 2006-11-02
Anticipated expiration: 2026-02-27
Also published as: DE602006010134D1; EP1717182A3; JP2006306588A; EP1717182B1

Abstract

The present invention provides a yarn slack eliminating device in a textile machine which allows a yarn hooking member to offer a stable rotational resistance to a slack eliminating roller to enable the formation of packages of a stable quality. A yarn slack eliminating device 12 includes a rotatively driven slack eliminating roller 21 and a yarn hooking member 22 attached concentrically and relatively rotatably to the slack eliminating roller 21. A flyer shaft 33 of the yarn hooking member 22 includes a columnar portion 35 the axis of which coincides with a rotation axis. A permanent magnet 36 is placed around an outer peripheral surface of the columnar portion 35. A hysteresis material is placed opposite the permanent magnet in a radial direction. A cylindrical adjustment bolt 32 in which the hysteresis material 37 is installed is screwed into a nut member 31 fixed to the slack eliminating roller 21. Rotating the adjustment bolt 32 enables a change in the opposite area of the permanent magnet 36 and hysteresis material 37 (Fig. 4).

Description

Field of the Invention

The present invention relates to a yarn slack eliminating device that eliminates a slack that may occur between a spinning device and a winding device in a textile machine such as a spinning machine.

Background of the Invention

Conventional high-speed spinning machines such as pneumatic spinning machines which wind a spun yarn to form a package are configured as described below. A detected yarn defect is cut using a cutter and then removed, and a yarn splicing device subsequently splices the tip of a yarn continuously fed by a spinning device and a yarn end on a package side. This yarn splicing operation is performed with yarn winding stopped, thus requiring a yarn slack to be eliminated.
In view of this, the Unexamined Japanese Patent Application Publication (Tokkai) No. 2004-277946 (Figure 18 and paragraphs 0024 to 0026) discloses a yarn slack eliminating device comprising a rotatively driven slack eliminating roller and a rotary yarn hooking member. The yarn hooking member of the yarn slack eliminating device is attached concentrically and relatively rotatably to the slack eliminating roller. An appropriate resistance can be offered to the relative rotation through the pressing force (frictional force) of a transmission force applying member being composed of urging means such as a spring. The pressing force (frictional force) can be steplessly adjusted by a tightening operation using a transmission force adjustment operating portion having a threading portion.
As described above, with the configuration in accordance with the Unexamined Japanese Patent Application Publication (Tokkai) No. 2004-277946 , the relative rotational resistance of the yarn hooking member is realized by the pressing force (frictional force) of the transmission force applying member. However, the relative rotational resistance is often unstably owing to, for example, an unintended factor such as damage to a friction surface or an age-based factor such as the wear of the friction surface.
Where a yarn is unwound from the slack eliminating roller, the relative rotational resistance is a factor determining the winding tension of the yarn. When a winding tension suitable for the yarn type or yarn thickness is not stably obtained, the shape of the package or the yarn unwinding during a post-process may be affected.
Consequently, the yarn slack eliminating device configured in accordance with the Unexamined Japanese Patent Application Publication (Tokkai) No. 2004-277946 still needs to be improved so as to allow high-quality packages to be stably obtained.
The present invention has been made in view of the above circumstances. An object of the present invention is to provide a yarn slack eliminating device that offers a stable rotational resistance to the slack eliminating roller of the yarn hooking member to form packages of a stable quality.

Summary of the Invention

A description has been given of the problems to be solved by the present invention. A description will be given of means for solving the problems and its effects.
A first aspect of the present invention provides a yarn slack eliminating device in a textile machine comprising a rotatively driven slack eliminating roller and a yarn hooking member attached concentrically and relatively rotatably to the slack eliminating roller, one of the slack eliminating roller and the yarn hooking member comprising a permanent magnet and the other comprising a hysteresis material.
The expression "comprising the permanent magnet" means not only that the permanent magnet is provided in the slack eliminating roller or the yarn hooking member but also that the slack eliminating roller or yarn hooking member itself is magnetized to form a permanent magnet.
The above configuration enables the improvement of the lasting stability and reliability of the rotational resistance. In particular, the above configuration can stably offer a low rotational resistance that allows an appropriate unwinding tension to be applied to a yarn unwound from the slack eliminating roller. This is very suitable for textile machines.
The yarn slack eliminating device in the textile machine is preferably configured as described below. The yarn hooking member comprises a columnar portion the axis of which coincides with a rotation axis. One of the permanent magnet and the hysteresis material is placed around an outer peripheral surface of the columnar portion, whereas the other of the permanent magnet and the hysteresis material is placed opposite the one of the permanent magnet and the hysteresis material in a radial direction.
This enables a portion offering the rotational resistance to be housed in a small space, and the yarn slack eliminating device can thus be compactly constructed. Further, the part of the yarn hooking member in which the permanent magnet or hysteresis material is installed is formed like a column that is concentric with the rotation axis. This makes it possible to reduce the inertia moment of the yarn hooking member to allow a variation in a yarn draw-out speed to be successfully followed.
In the yarn slack eliminating device in the textile machine, the permanent magnet and the hysteresis material are configured so as to be movable relative to each other in an axial direction and so that the relative movement enables a change in the opposite area of the permanent magnet and the hysteresis material.
This enables a change in the magnetic coupling intensity between the permanent magnet and the hysteresis material, thus making it possible to flexibly deal with a change in yarn type or yarn thickness.
The yarn slack eliminating device in the textile machine is preferably configured as described below. A cylindrical member is provided around an outer periphery side of the columnar portion, and the permanent magnet or the hysteresis material is placed around an inner periphery of the cylindrical member. Threaded portions are formed on the cylindrical member and on the slack eliminating roller, and the cylindrical member can be threadably moved in an axial direction by rotating the cylindrical member with respect to the slack eliminating roller.
This enables the rotational resistance of the yarn hooking member to be easily changed by rotating the cylindrical member.
The position of the cylindrical member can be precisely adjusted by threadably moving the threaded portion. This configuration is thus suitable for precisely adjusting the rotational resistance of the yarn hooking member.
A second aspect of the present invention provides a textile machine comprising a yarn slack eliminating device configured as described above.
This makes it possible to improve the lasting stability and reliability of tension of the yarn unwound from the slack eliminating roller, and the quality of packages formed can thus be improved.

Brief Description of the Drawings

Figure 1 is a front view showing a general configuration of a spinning machine to which a yarn slack eliminating device in accordance with the present invention is applied.
Figure 2 is a vertically sectional side view of the spinning machine.
Figure 3 is a partly sectional side view showing a general configuration of the yarn slack eliminating device.
Figure 4 is an enlarged sectional view showing the configuration of a slack eliminating roller and a yarn hooking member.
Figure 5 is an enlarged sectional view showing that the slack eliminating roller and yarn hooking member shown in Figure 4 have been moved by rotating an adjustment bolt.

Detailed Description of the Preferred Embodiments

Now, with reference to the drawings, a description will be given of a spinning machine that is a textile machine in accordance with an embodiment of the present invention. The terms "upstream" and "downstream" refer to an upstream and downstream sides, respectively, based on the direction in which a yarn runs during spinning. Figure 1 is a front view showing a general configuration of a spinning machine to which a yarn slack eliminating device in accordance with the present invention is applied. Figure 2 is a vertically sectional side view of the spinning machine.
Figure 1 shows a spinning machine 1 comprising a large number of spinning units 2 arranged in a line. The spinning machine 1 is provided with a yarn splicing carriage 3 that can run in a direction in which the spinning units 2 are arranged, a blower box 4, and a motor box 5.
As shown in Figure 1, each of the spinning units 2 is mainly composed of a draft device 7, a spinning device 9, a yarn feeding device 11, a yarn slack eliminating device 12, and a winding device 13 which are arranged in this order from an upstream side to a downstream side. The draft device 7 is provided in the vicinity of an upper end of a casing 6 of the spinning machine 1 main body. A fiber bundle 8 fed by the draft device 7 is spun by the spinning device 9. A spun yarn 10 discharged from the spinning device 9 is fed, by the yarn feeding device 11, through a yarn clearer 52, described later, and the yarn is then wound by the winding device 13 to form a package 45.
As shown in Figure 2, the draft device 7 drafts a sliver 15 into a fiber bundle 8. The draft device 7 is composed of, for example, four rollers, a back roller 16, a third roller 17, a middle roller 19 around which an apron belt 18 is installed, and a front roller 20.
The detailed configuration of the spinning device 9 is not shown in the drawing. In the present embodiment, the spinning device 9 is of a pneumatic type that utilizes a whirling air current to generate a spun yarn 10 from the fiber bundle 8.
The yarn feeding device 11 is composed of a delivery roller 39 supported on the casing 6 of the spinning machine 1 main body, and a nip roller 40 that contacts the delivery roller 39. In this configuration, the spun yarn 10 discharged from the spinning device 9 is sandwiched between the delivery roller 39 and the nip roller 40. The delivery roller 39 is rotatively driven by an electric motor (not shown in the drawings) to feed the spun yarn 10 toward the winding device 13.
The winding device 13 comprises a cradle arm 71 supported so as to be pivotable around a support shaft 70, and the cradle arm 71 can rotatably support a bobbin around which the spun yarn 10 is wound. The winding device 13 further comprises a winding drum 72 that abuts against a peripheral surface of a bobbin or a package 45 formed by winding the spun yarn 10 around the bobbin, and a traverse device (not shown in the drawings). The winding drum 72 is driven by an electric motor (not shown in the drawings) to rotate the package 45, which is in contact with the winding drum 72, and the spun yarn 10 is thus wound.
The yarn clearer 52 is provided in the front side of the casing 6 of the spinning machine 1 and slightly downstream of the yarn feeding device 11. The spun yarn 10 spun out by the spinning device 9 passes through the yarn clearer 52 before being wound by the winding device 13. The yarn clearer 52 monitors the thickness of the running spun yarn 10. Upon detecting a yarn defect in the spun yarn 10, the yarn clearer 52 transmits a yarn defect detection signal to a unit controller (not shown in the drawings).
Upon receiving the yarn defect detection signal, the unit controller immediately uses a cutter 57 to cut the yarn and further stops the draft device 7, the spinning device 9, and the like. The unit controller further causes the yarn splicing carriage 3 to run to the spinning unit 2. The unit controller subsequently drives the spinning device 9 and the like again and causes the yarn splicing carriage 3 to splice the yarn. The unit controller then causes spinning and winding to be resumed.
As shown in Figure 1, the yarn splicing carriage 3 runs on a rail 41 provided in the casing 6 of the spinning machine 1 main body. The carriage 3 comprises a yarn splicing device (for example, splicer) 43, a suction pipe 44 that can be turned upward and downward in the carriage 3 and which swings around a shaft, while sucking and catching a yarn end discharged from the spinning device 9 and guiding it to the yarn splicing device 43, and a suction mouth 46 that can be turned upward and downward in the carriage 3 and which swings around a shaft, while sucking and catching a yarn end from the package 45 rotatably supported by the winding device 13 and guiding it to the yarn splicing device 43.
The yarn slack eliminating device 12, provided in each of the plurality of spinning units 2, can be engaged with the spun yarn 10 or prevented from engaging with the spun yarn 10.
Specifically, as shown in Figure 3, the yarn slack eliminating device 12 mainly comprises a slack eliminating roller 21 around the outer periphery of which the spun yarn 10 is wound and stored, a yarn hooking member 22 that rotates integrally with or independently of the slack eliminating roller 21 depending on conditions, an upstream side guide 23 placed slightly upstream side of the slack eliminating roller 21, an air cylinder (forward and backward moving means) 24 that drives the upstream side guide 23 so that it moves forward or backward, an electric motor (driving means) 25 that drives the slack eliminating roller 21, and a downstream side guide 26 provided downstream side of the slack eliminating roller 21.
The slack eliminating roller 21, upstream side guide 23, air cylinder 24, electric motor25, downstream side guide 26, and the like are supported in the spinning unit 2 via a fixing member such as a bracket 27.
As shown in the enlarged diagram in Figure 4, the slack eliminating roller 21 is mainly composed of a roller main body 42 and a nut member 31 secured integrally to the inside of the roller main body 42. When that side of an outer peripheral surface 42a of the roller main body 42 which has the yarn hooking member 22 is defined as a leading end and that side of the outer peripheral surface 42a which is connected to the electric motor 25 is defined as a base end, a taper portion (a), a cylindrical portion (b), and a taper portion (c) are formed in this order from the base end to leading end of the outer peripheral surface 42a. The taper portions (a), (c) are gently tapered so that their end surface side has a larger diameter. The cylindrical portion (b) is shaped to have an almost uniform diameter and is seamlessly connected to the opposite taper portions (a), (c).
The roller main body 42 is fixed to a motor shaft 25a of the electric motor 25 via an appropriate set screw 28 screwed into the roller main body 42 in a radial direction.
During a yarn splicing operation by the yarn splicing carriage 3, the yarn hooking portion 22 of the yarn slack eliminating device 12 winds the spun yarn 10 from the spinning device 9 side around the outer peripheral surface 42a of the slack eliminating roller 21 (roller main body 42); the winding starts from the base end side and progresses toward the leading end. Once the yarn splicing operation is finished, the spun yarn 10 wound and stored around the outer peripheral surface 42a is unwound via the yarn hooking device 22; the unwinding starts from the leading end side and progresses toward the winding device 13 side.
In the outer peripheral surface 42a of the roller main body 42, the taper portion (a) at the base end side smoothly moves the supplied and wound spun yarn 10 from the larger diameter portion to the smaller diameter portion until the spun yarn 10 reaches the intermediate cylindrical portion (b). The spun yarn 10 is regularly wound around the surface of the cylindrical portion (b). The taper portion (c) at the leading end side has a function of preventing a slip-out phenomenon in which all the wound spun yarn 10 slips out at a time during unwinding. The taper portion (c) also has a function of sequentially winding back the spun yarn 10 from the smaller diameter portion to the larger diameter portion at the end surface side to ensure the smooth drawing-out of the spun yarn 10.
As shown in Figures 3 and 4, the yarn hooking member 22, located at the leading end side of the slack eliminating roller 21, is attached concentrically rotatably to the slack eliminating roller 21. Specifically, the yarn hooking member 22 is composed of a relatively rotatably supported flyer shaft 33 and a flyer 38 secured to the leading end.
With reference to Figure 4, a detailed description will be given of how the yarn hooking member 22 is attached. A concave portion 42b is formed at the leading end side of the roller main body 42 of the slack eliminating roller 21, and a nut member 31 is integrally fixed in the concave portion 42b by an appropriate method such as press fitting so as to be concentric with the roller main body 42.
An adjustment bolt 32 is screwed into the nut member 31 through the leading end surface side of the roller main body 42. The adjustment bolt 32 is shaped to have a cylindrical hole that penetrates the bolt 32, and a head of the adjustment bolt 32 has a known hexagonal shape. Threaded portions 29 are formed on a shaft portion of the adjustment bolt 32 and on the nut member 31.
The flyer shaft 33 is inserted through the cylindrical hole in the nut member 31, and the flyer shaft 33 is rotatably supported on inner peripheral surfaces of the nut member 31 and adjustment bolt 32 via bearings 34, 34. A leading end of the flyer shaft 33 projects from the leading end surfaces of the adjustment bolt 32 and slack eliminating roller 21. The flyer 38 is fixed to the leading end of the flyer shaft 33.
The flyer 38 rotates integrally with the flyer shaft 33. The flyer 38 is appropriately bent from the periphery of leading end surface of the roller main body 42 toward the outer peripheral surface 42a so as to engage with the spun yarn 10 (the spun yarn 10 is hooked to the flyer 38) to reliably wind the spun yarn 10 around the outer peripheral surface 42a of the roller main body 42.
The flyer shaft 33 comprises a columnar portion 35 located in its middle in its axial direction and having a slightly larger diameter, and an outer peripheral surface of the columnar portion 35 can be located opposite the inner peripheral surface of the adjustment bolt 32 in the radial direction of the columnar portion 35. The diameter of the columnar portion 35 is preferably minimized to allow the columnar portion 35 to successfully follow a variation in yarn draw-out speed.
A permanent magnet 36 is placed around the outer peripheral surface of the columnar portion 35. The permanent magnet 36 is magnetized so as to alternately form an N pole and a S pole in its circumferential direction. A hysteresis material (semi-rigid magnetic material) 37 is placed around the inner peripheral surface of the adjustment bolt 32.
The permanent magnet 36 and the hysteresis material 37 lie opposite each other in their radial direction (that is, in a non-contact manner) so that an appropriate cylindrical gap is created between them. When the yarn type or thickness is changed, the opposite area of the hysteresis material 37 and permanent magnet 36 can be changed by gripping the head of the adjustment bolt 32 (or using an appropriate tool) to rotate and screw the adjustment bolt 32 through the nut member 31 so that the adjustment bolt 32 moves threadably in the axial direction relative to the columnar portion 35 of the flyer shaft 33 to move the hysteresis material 37 relative to the permanent magnet 36. Figure 5 shows that the hysteresis material 37 as shown in Figure 4 has been moved together with the adjustment bolt 32 as shown in Figure 4.
By changing the opposite area of the permanent magnet 36 and hysteresis material 37 as described above, it is possible to steplessly adjust the rotational resistance of the flyer 38 to the slack eliminating roller 21. That is, where the permanent magnet 36 and the hysteresis material 37 lie opposite each other over a large area as shown in Figure 4, a tight magnetic coupling occurs between the permanent magnet 36 and the hysteresis material 37, and this results in a strong resistance to the relative rotation of the flyer 38 and the slack eliminating roller 21. On the other hand, if the opposite area of the permanent magnet 36 and hysteresis material 37 is almost zero as shown in Figure 5, the flyer 38 can rotate almost independently of the slack eliminating roller 21. The present embodiment thus enables the relative rotational resistance of the flyer 38 to the slack eliminating roller 21 to be arbitrarily adjusted by rotating and moving the adjustment bolt 32 in the axial direction.
The upstream side guide 23 is driven forward and backward by the air cylinder 24. When the upstream side guide 23 is at a forward position (shown by a solid line in Figure 3), a yarn path for the spun yarn 10 is held by the upstream side guide 23 so as to prevent the spun yarn 10 from engaging with the yarn slack eliminating device 12. When the upstream side guide 23 is at a backward position (shown by a chain line in Figure 3), the yarn path is moved to a position where the spun yarn 10 engages with the yarn slack eliminating device 12 and is wound around the slack eliminating roller 21.
Now, a description will be given of the operation of the spinning machine 1 configured as described above. Each spinning unit 2 of the spinning machine 1 causes the draft device 7 to feed the fiber bundle 8 into the spinning device 9. The spun yarn 10 spun and generated by the spinning device 9 is fed downstream side by the yarn feeding device 11, and the spun yarn 10 then passes through the cutter 57 and yarn clearer 52 and is finally fed to the winding device 13 via the yarn slack eliminating device 12. The spun yarn 10 is then wound into a package 45.
If the yarn clearer 52 of any spinning unit 2 detects a defect in the spun yarn 10, the unit controller (not shown in the drawings) of the spinning unit 2 uses the cutter 57 to cut the spun yarn 10. At almost the same time, the unit controller stops the rotation of the back roller 16 and third roller 17 of the draft device 7. The fiber bundle 8 is cut between the stopped third roller 17 and the continuously rotating middle roller 19 in such a way that it is torn off.
A part of the spun yarn 10 which is located downstream side of the cut portion is sucked and removed by suction means (not shown in the drawings).
The unit controller of the spinning unit 2 then transmits a yarn splicing request signal to the yarn splicing carriage 3, which moves to and stops at a position where it stands opposite the spinning unit 2. The unit controller then starts rotating the slack eliminating roller 21 of the yarn slack eliminating device 12 at an appropriate time. At the same time, the upstream side guide 23 of the yarn slack eliminating device 12 is advanced by the air cylinder 24 to hold the yarn path so that the next spun yarn 10 to be spun engages with the yarn hooking member 22 in the yarn slack eliminating device 12 only when required.
Then, when the suction pipe 44 in the yarn splicing carriage 3 is rotatively moved upward, the draft device 7 and spinning device 9 start to be driven almost in synchronism with the rotative movement. The spun yarn 10 spun out by the spinning device 9 is thus sucked by caught in the suction pipe 44. At the same time, in the winding device 13 side, the suction mouth 46 in the yarn splicing carriage 3 is rotatively moved downward to suck and catch the yarn end wound around the package 45. The suction pipe 44 and the suction mouth 46 guide the sucked yarn ends to the yarn splicing device 43 for yarn splicing.
Immediately before the yarn splicing device 43 starts a yarn splicing operation, the air cylinder 24 in the yarn slack eliminating device 12 withdraws to move the upstream side guide 23 to the backward position. The yarn path for the spun yarn 10 is then changed so as to coincide with the rotation trajectory of the flyer 38 as show by a chain line in Figure 3. This allows the spun yarn 10 to be wound around the outer peripheral surface 42a of the slack eliminating roller 21 by the flyer 38.
That is, during the yarn splicing operation of the yarn splicing device 43, the spinning device 9 continues to spin out the spun yarn 10. This may result in a large amount of spun yarn 10 remaining upstream side of the yarn splicing device 43. During a yarn splicing operation by the splicing device 43, the yarn slack eliminating device 12 accordingly winds the spun yarn 10 around the slack eliminating roller 21 to prevent the spun yarn 10 from slacking or remaining. The yarn slack eliminating device 12 thus achieves a smooth yarn splicing and spinning resuming operations.
As previously described, the flyer 38 and the flyer shaft 33 can rotate independently of the slack eliminating roller 21. The previously described mechanism being composed of the permanent magnet 36 and hysteresis material 37 allow the flyer 38 to rotate integrally with the slack eliminating roller 21 unless a load of at least a given magnitude (the load overcoming the magnetic coupling between the permanent magnet 36 and the hysteresis material 37) is imposed on the flyer 38. During the yarn splicing operation, the downstream side of the spun yarn 10 is at a stop, with only a light load imposed on the flyer 38. The flyer 38 thus rotates integrally with the slack eliminating roller 21 to wind the spun yarn 10 around the outer periphery of the slack eliminating roller 21.
Once the yarn splicing device 43 finishes the yarn splicing operation, the package 45 is rotated by the winding drum 72 in the winding device 13 and thus starts to be wound again.
As described above, the spun yarn 10 spun out by the spinning device 9 is continuously wound around the outer peripheral surface 42a of the continuously rotating slack eliminating roller 21 between the start of the yarn splicing operation by the yarn splicing device 43 and the resumption of winding. However, when the winding device 13 resumes a winding operation, the speed at which the spun yarn 10 is wound around the slack eliminating roller 21 is higher than that at which the spun yarn 10 is drawn out from the slack eliminating roller 21. This is because the ratio of the feeding speed of the yarn feeding device 11 to the winding speed of the winding device 13 is set so as to apply an appropriate tension to the spun yarn 10. Consequently, the flyer 38 of the yarn slack eliminating device 12 rotates independently of the slack eliminating roller 21, continuously rotating in the winding direction. The spun yarn 10 wound and stored on the slack eliminating roller 21 is thus gradually unwound.
While the spun yarn 10 is being unwound from the slack eliminating roller 21, the flyer 38 guides the spun yarn 10 so as to allow it to be averagely unwound from the slack eliminating roller 21, while preventing it from slipping out.
The flyer 38 contacts the spun yarn 10 to apply an appropriate resistance and thus an appropriate tension to it, thus allowing it to be successfully wound around the package 45.
That is, the flyer 38 in accordance with the present embodiment has a yarn hooking function of introducing the spun yarn 10 into the slack eliminating roller 21 immediately before the start of a yarn splicing operation. The flyer 38 also has a function of applying a predetermined unwinding tension to the spun yarn 10 before unwinding the spun yarn 10 wound around the slack eliminating roller 21. The present embodiment applies the unwinding tension by offering a resistance based on the magnetic coupling between the permanent magnet 36 and the hysteresis material 37, to the rotation of the flyer shaft 33 (flyer 38) relative to the slack eliminating roller 21.
The relative rotational resistance is thus offered to the rotation of the flyer 38 to the slack eliminating roller 21 on the basis of the non-contact magnetic coupling. This makes it possible to improve the lasting stability and reliability of the rotational resistance. The winding device 13 can thus stably form packages 45 of an appropriate shape.
The configuration in accordance with the Unexamined Japanese Patent Application Publication (Tokkai) No. 2004-277946 utilizes the pressing force (frictional force) of the transmission force applying member to allow the yarn hooking member to offer the relative rotational resistance. Consequently, the frictional force obtained is unsatisfactorily stable, resulting in frequent irregular or temporal variations in rotational resistance owing to a long-term use.
In particular, in textile machines that wind a yarn into a package, the yarn hooking member 22 (flyer 38) needs to offer a substantially small rotational resistance in order to apply an appropriate unwinding tension (winding tension) to the yarn. Consequently, the above variation in rotational resistance exerts a big bad influence on the quality of the package. Specifically, even a slight change in the friction state of the transmission force applying member may degrade the quality of the package; the yarn may be slip off from the end surface of the package or steps may be formed on the end surface of the package.
In contrast, the yarn slack eliminating device 12 in accordance with the present embodiment allows the flyer 38 to offer a rotational resistance in a non-contact manner. This makes it possible to stably offer a substantially small rotational resistance as described above. This in turn makes it possible to successfully stabilize the tension of the spun yarn 10 being unwound from the slack eliminating roller 21, and the quality of the package 45 can thus be markedly improved.
In the yarn slack eliminating device 12 in accordance with the present embodiment, the flyer shaft 33 of the yarn hooking member 22 comprises the columnar portion 35 the axis of which coincides with the rotation axis. The permanent magnet 36 is placed around the outer peripheral surface of the columnar portion 35, and the hysteresis material 37 is placed opposite the permanent magnet 36 in the radial direction. This allows the portion offering a rotational resistance to be housed in a small space, thus making it possible to compactly construct the yarn slack eliminating device 12. Further, the part of the yarn hooking member 22 in which the permanent magnet 36 is installed is formed like a column that is concentric with the rotation axis. This makes it possible to reduce the inertia moment of the yarn hooking member 22 to allow a variation in the yarn draw-out speed of the spun yarn 10 to be successfully followed.
A comparison of Figure 4 with Figure 5 clearly indicates that the present embodiment allows the permanent magnet 36 and the hysteresis material 37 to move relative to each other in the axial direction. This relative movement enables a change in the opposite area of the permanent magnet 36 and hysteresis material 37. The rotational resistance of the yarn hooking member 22 (flyer 38) can thus be arbitrarily varied by changing the level of the magnetic coupling between the permanent magnet 36 and the hysteresis material 37. This makes it possible to flexibly deal with a change in yarn type or yarn thickness.
The present embodiment also comprises the cylindrical adjustment bolt 32, which covers the outer periphery of the columnar portion 35, and the hysteresis member 37 is placed around the inner peripheral surface of the adjustment bolt 32. The threaded portions 29 are formed on the adjustment bolt 32 and on the nut member 31 in the slack eliminating roller 21, and rotating the adjustment bolt 32 relative to the slack eliminating roller 21 thus enables the adjustment bolt 32 to be threadably moved in the axial direction. This allows the rotational resistance of the yarn hooking member 22 to be easily changed by rotating the adjustment bolt 32. The threaded portions 29 also enable the position of the adjustment bolt 32 to be adjusted both precisely and easily. The threaded portions 29 further enable the rotational resistance of the yarn hooking member 22 (flyer 38) to be precisely adjusted.
The preferred embodiment of the present invention has been described above. The above embodiment can be modified, for example, as described below.

(1) For the permanent magnet 36, a cylindrical permanent magnet may be externally fitted around the columnar portion 35 or the outer peripheral surface of the columnar portion 35 may be directly magnetized to form a permanent magnet.
(2) The arrangement of the permanent magnet 36 and hysteresis material 37 may be inverted. That is, the permanent magnet may be placed around the inner peripheral surface side of the adjustment bolt 32, whereas the hysteresis material may be placed around the outer peripheral surface side of columnar portion 35 of the flyer shaft 33. Alternatively, the permanent magnet and the hysteresis material may be arranged opposite each other in the axial direction by, for example, constructing a disk-like portion in the middle of the flyer shaft 33 in place of the columnar portion.
(3) Figure 1 illustrates the cheese package 45 formed by winding the yarn around a straight bobbin. However, the yarn slack eliminating device 12 is applicable to a cone-like package formed by winding the yarn around a cone bobbin. With the cone-like package, the winding speed varies periodically as the traverse device in the winding device 13 traverses the yarn. However, the above configuration with the permanent magnet and hysteresis material enables the yarn slack eliminating device 12 to follow the variation in winding speed both appropriately and stably.
(4) The specific configuration of the slack eliminating roller 21 is not limited to the one described above. For example, the roller main body 42 and the nut member 31 may be formed into an integral member. Further, the method of fixing the roller main body 42 to the motor shaft 25a is not limited to the use of the set screw 28.
(5) In the present embodiment, the columnar portion 35 is solid. However, the columnar portion 35 may be hollow so as to reduce the inertia moment.
(6) In the above embodiment, the yarn slack eliminating device 12 is installed in the spinning machine 1. However, the present invention is not limited to this. The present embodiment is applicable to common textile machines comprising a yarn splicing device and the like.

Claims

A yarn slack eliminating device in a textile machine characterized by comprising a rotatively driven slack eliminating roller and a yarn hooking member attached concentrically and relatively rotatably to the slack eliminating roller, one of the slack eliminating roller and the yarn hooking member comprising a permanent magnet and the other comprising a hysteresis material.
A yarn slack eliminating device according to Claim 1, characterized in that the yarn hooking member comprises a columnar portion the axis of which coincides with a rotation axis, and one of the permanent magnet and the hysteresis material is placed around an outer peripheral surface of the columnar portion, whereas the other of the permanent magnet and the hysteresis material is placed opposite the one of the permanent magnet and the hysteresis material in a radial direction.
A yarn slack eliminating device according to Claim 2, characterized in that the permanent magnet and the hysteresis material are configured so as to be movable relative to each other in an axial direction and so that the relative movement enables a change in the opposite area of the permanent magnet and the hysteresis material.
A yarn slack eliminating device according to Claim 3, characterized in that a cylindrical member is provided around an outer periphery side of the columnar portion and the permanent magnet or the hysteresis material is placed around an inner periphery of the cylindrical member, and in that threaded portions are formed on the cylindrical member and on the slack eliminating roller, and the cylindrical member can be threadably moved in an axial direction by rotating the cylindrical member with respect to the slack eliminating roller.
A textile machine comprising a yarn slack eliminating device according to any one Claims 1 to 4.