BACKGROUND OF THE INVENTION
(1) Field of the Invention
[0001] In a textile machine of a spinning machine, the present invention relates to a spinning
machine having yarn slack eliminating device for eliminating slacks of a yarn that
may occur between a spinning device and a package winding device.
(2) Description of the Related Art
[0002] In a conventional high speed spinning machine such as an air type spinning machine
for winding a spun yarn to form a package, if a yarn defect is detected, the tread
defect is cut away by cutting means such as a cutter, and yarn tips which are sequentially
sent from the spinning device and yarn ends on the side of the package are pieced
by a piecing device. The piecing operation is carried out in a state where the winding
operation of yarn is stopped. Therefore, it is necessary to eliminate slacks in the
yarn between the spinning device and the package winding device.
[0003] As such a technique for eliminating slack in a yarn, there is proposed yarn slack
eliminating device of a spinning machine as described, for example, in
Japanese Patent Application Laid-open No.2004-277946 (Fig. 18, paragraphs [0024] to [0026]). The yarn slack eliminating device described
in this Japanese Patent Application includes a yarn slack eliminating roller 21 which
is rotated, and a rotary yarn hooking member 22. The yarn hooking member 22 is mounted
on the yarn slack eliminating roller 21 such that the yarn hooking member 22 can relatively
rotate concentrically with respect to the yarn slack eliminating roller 21, and a
resistance of appropriate strength can be applied to the relative rotation by a pressing
force (friction force) of a transmission force applying member 22f comprising biasing
means such as a spring. The pressing force (friction force) can be adjusted in a stepless
manner by a fastening operation of a transmission force adjusting section 22g having
a yarning portion.
[0004] According to the technique of the above-mentioned Japanese Patent Application, since
the relative rotation resistance of the yarn hooking member 22 is realized by the
pressing force (friction force) of the transmission force applying member 22f, the
relative rotation resistance can not be obtained stably in many cases due to unintentional
factor such as flaw on a friction surface or change over time factor such as wear
on the friction surface.
[0005] According to the technique of this Japanese Patent Application, when a yarn Y is
released from the yarn slack eliminating roller 21, the relative rotation resistance
is one of factors which determines a yarn winding tension, and if appropriate winding
tension can not stably be obtained in accordance with a kind of yarn and a thickness
of a yarn, a shape off the package 16 and the yarn releasing properties in subsequent
steps are adversely influenced.
[0006] To solve this problem, the present assignee have already proposed a magnetic tensor
device as shown in Figs. 5 and 6 as yarn slack eliminating device of a spinning machine,
etc. capable of applying stable arbitrary winding tension, and have filed an patent
application of this magnetic tensor device. As shown in Figs. 5 and 6, the magnetic
tensor device generates a constant rotation torque between the yarn slack eliminating
roller 71 and the rotatable yarn hooking member 72 in combination with a hysteresis
material 87 and a permanent magnet 86, and changes an area where the hysteresis material
87 and the permanent magnet 86 are superposed (displacement by rotation operation
of the adjusting bolt 82 as shown in Figs. 5 and 6), thereby adjusting the torque
to an arbitrary rotation torque.
[0007] In the magnetic tensor device shown in Figs. 5 and 6, however, when a lot is changed,
or rotation torques of many spindles are to be changed, it is necessary to adjust
the spindles one by one, and much labor is required. Further, it is difficult to change
a rotation torque while keeping the winding operation of a yarn due to its mechanism,
and it is impossible to finely adjust during spinning and to positively change a rotation
torque.
[0008] EP 1 457 448 A2 discloses a spinning machine with a slack eliminating device. The slack eliminating
device comprises a slack eliminating roller and a bar-like member, which can be rotated
synchronously or independently from each other. The bar like-member is mounted on
a wheel member and is in frictional contact with a friction assembly comprising a
nut, a presser member and a force applying member. By adjusting the frictional force
between the wheel member and the friction assembly the threshold value of the rotation
torque for independent rotation of the slack eliminating roller and the bar-like member
is determined. Alternatively the threshold value of the rotation torque is adjusted
on the basis of an electromagnetic force. A tension sensor is proposed, to monitor
the tension of the yarn being unwound. EP'448 does not teach to positively change
the rotation torque during spinning out operation, and to control the rotation torque
based on the measurement signal of the tension measurement device.
[0009] US 6 244 395 B1 discloses an electromagnetic hysteresis brake consisting of a stationary brake magnet,
inner and outer pole ring parts, an electromagnet, a rotating armature, a permanent
magnet and a hysteresis ring projecting into an annular air gap which is formed between
the inner and the outer pole ring parts. The electromagnet is controlled by an external
controller, to adjust the magnetic friction force acting on the rotating armature.
This document does not disclose to control the rotation torque between a yarn slack
eliminating roller and a yarn hooking member by feedback control based on a tension
measurement signal.
SUMMARY OF THE INVENTION
[0010] Hence, the present invention has been accomplished to solve all of the problems in
the conventional technique, and an especially important element is to provide yarn
slack eliminating device provided therein with an electromagnetic tensor capable of
realizing a stable rotation resistance with respect to a yarn slack eliminating roller
of the yarn hooking member, and capable of forming a package of stable quality.
[0011] To achieve the above object, according to a first aspect of the present invention,
yarn slack eliminating device in which an electromagnetic tensor is incorporated includes
a rotating and driving source, a yarn slack eliminating roller which is rotated and
driven by the rotating and driving source, and a yarn hooking member which is mounted
on the yarn slack eliminating roller such that the yarn hooking member can relatively
rotate concentrically with the yarn slack eliminating roller, the yarn slack eliminating
roller is provided with magnetic field forming means by electromagnet so that a magnetic
field is applied to the yarn hooking member, a rotation torque is generated between
the yarn slack eliminating roller and the yarn hooking member by the magnetic field
generated by the magnetic field forming means, and the rotation torque is controlled
by input control to the electromagnet.
[0012] The rotation torque is set between the yarn slack eliminating roller and the yarn
hooking member in unison from a control device with respect to the yarn slack eliminating
device of each spinning unit.
[0013] Each of the spinning units includes yarn tension measuring means for measuring an
actual yarn tension at the time of a spinning out operation, and a rotation torque
between the yarn slack eliminating roller and the yarn hooking member is feedback
controlled based on a tension measurement signal.
[0014] According to a second aspect of the invention, the yarn slack eliminating device
in which the electromagnetic tensor is incorporated in the first aspect of the invention
is provided, wherein the magnetic field forming means includes a stationary annular
exciting coil, an outer magnetic pole member having an outer magnetic pole is disposed
outside the exciting coil, an inner magnetic pole member having an inner magnetic
pole is disposed inside the exciting coil, the outer and inner magnetic pole members
and the yarn slack eliminating roller are integrally rotated, a magnetic field is
generated between the outer magnetic pole and the inner magnetic pole, and an annular
member of hysteresis material is disposed integrally with the yarn hooking member
so as to intersect with the magnetic field generated between the outer magnetic pole
and the inner magnetic pole.
[0015] According to the yarn slack eliminating device in which the electromagnetic tensor
of the invention is incorporated, the magnetic field forming means by the electromagnet
is provided in the yarn slack eliminating roller, the rotation torque is generated
between the yarn slack eliminating roller and the yarn hooking member by the magnetic
field generated by the magnetic field forming means, and the rotation torque is controlled
by the input control to the electromagnet. With this, it is possible to realize a
stable rotation resistance against the yarn slack eliminating roller of the yarn hooking
member, and to form a package of stable quality.
[0016] Further, according to this invention, the magnetic field forming means includes a
stationary annular exciting coil, an outer magnetic pole member having an outer magnetic
pole is disposed outside the exciting coil, an inner magnetic pole member having an
inner magnetic pole is disposed inside the exciting coil, the outer and inner magnetic
pole members and the yarn slack eliminating roller are integrally rotated, a magnetic
field is generated between the outer magnetic pole and the inner magnetic pole, and
an annular member of hysteresis material is disposed integrally with the yarn hooking
member so as to intersect with the magnetic field generated between the outer magnetic
pole and the inner magnetic pole. With this, if current flows through the exciting
coil, the magnetic field rotates together with the yarn slack eliminating roller,
and a relative rotation torque is obtained in the yarn hooking member with respect
to the rotating yarn slack eliminating roller. This rotation torque is varied depending
upon the magnitude of the magnetic field and thus, if voltage or current applied to
the coil is varied, an arbitrary rotation torque can be obtained. As a result, if
a predetermined control value is input, an arbitrary rotation torque can be set with
a simple operation.
[0017] In this invention, with the above-described structure, if high-end control device
is provided, torques of the plurality of spindles can be changed at a time. It is
also possible to change a rotation torque during the spinning out operation and thus,
it is possible to positively change the tension during the winding operation. If means
for measuring an actual yarn tension at the time of the spinning out operation is
provided, feedback control based on its signal can be performed. Therefore, even if
the tension is varied due to some reason such as disturbance, it is possible to change
the magnetic field in real time and the tension can be returned to any tension.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018]
Fig. 1 is a schematic front view showing one example of the entire spinning machine
to which the present invention is applied;
Fig. 2 is a schematic partial sectional side view of the spinning machine shown in
Fig. 1;
Fig. 3 shows a concrete example of yarn slack eliminating device, and is a schematic
half sectional perspective view showing an internal structure thereof;
Fig. 4A is a schematic vertical sectional view of the yarn slack eliminating device
7, and Fig. 4B is a schematic transverse sectional view taken along the line 4B-4B
as viewed from the arrow in Fig. 4A;
Fig. 5 is a schematic side sectional view showing an example of a conventional magnetic
sensor which is a combination of a permanent magnet and a hysteresis material; and
Fig. 6 is a schematic side sectional view showing the conventional magnetic sensor
shown in Fig. 5 in which an adjusting bolt is displaced.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] Yarn slack eliminating device provided therein with an electromagnetic tensor of
the invention will be explained in detail based on a concrete embodiment shown in
the drawings.
[0020] Fig. 1 is a schematic front view showing one example of the entire spinning machine
to which the present invention is applied. Fig. 2 is a schematic partial sectional
side view of the spinning machine shown in Fig. 1.
[0021] First, a spinning machine 1 to which the present invention is applied will be explained.
As shown in Fig. 1, in the spinning machine 1, many spinning units U are arranged
in a longitudinal direction of the spinning machine 1 between a motor box MB and a
dust box DB. The spinning machine 1 is provided with rails R running along a direction
in which the spinning units U are arranged, and a piecing truck 3 can reciprocate
in the lateral direction on the rails R. The piecing truck 3 runs to the spinning
unit U which requires piecing, stops at a position of the corresponding spinning unit
U, and carries out the piecing operation.
[0022] As shown in Figs. 1 and 2, each spinning unit U includes a draft device 4, a spinning
device 5, a yarn feeding device 6, a slack eliminating device 7 and a winding device
8 as main constituent elements disposed from upstream to downstream. The draft device
4 is for drawing a sliver SL to obtain a fiber bundle Y. Each draft device 4 includes
four pairs of rollers, i.e., a pair of back rollers 9 including a top roller and a
bottom roller, a pair of side rollers 10, a pair of middle rollers 12 around which
an apron belt 11 is wound, and a pair of front rollers 13.
[0023] A detailed structure of the spinning device 5 is not illustrated but in this embodiment,
an air type structure is employed in which a turning wind current from an air injection
nozzle is utilized and a spun yarn SY is produced from a draught fiber bundle Y.
[0024] The yarn feeding device 6 includes a delivery roller 14 and a nip roller 15 provided
such that it comes into contact with the delivery roller 14. A spun yarn SY sent out
from the spinning device 5 is sandwiched between the delivery roller 14 and the nip
roller 15 and is sent downward by rotation of the delivery roller 14.
[0025] The spun yarn SY sent out from the spinning device 5 is fed downstream by the yarn
feeding device 6, and is winding around a winding package WP by the winding device
8 through a cutter device 16 which removes a defect of a yarn, a yarn clearer 17 and
yarn slack eliminating device 7.
[0026] The yarn clearer 17 monitors a thickness of the running spun yarn SY, and when the
yarn clearer 17 detects a yarn defect of the spun yarn SY, the yarn clearer 17 sends
a yarn defect detection signal to a unit controller (not shown). If the unit controller
receives the yarn defect detection signal, the unit controller immediately operates
the cutter device 16 to cut the yarn, stops the draft device 4 and the spinning device
5, and allows the piecing truck 3 to run in front of that spinning unit U. Then, the
spinning device 5 and the like are again driven, and the piecing truck 3 is allowed
to piece, and the spinning and winding operations are restarted.
[0027] As shown in Fig. 1, the piecing truck 3 is provided such that it run along the rails
R provided on a casing 2 of a main body of the spinning machine 1. The piecing truck
3 includes a suction pipe (supply side yarn end capturing means) 18 for sucking and
capturing a spun yarn SY which is continuously supplied from the supply side spinning
device 5, a suction mouth (winding side yarn end capturing means) 19 for sucking and
capturing a spun yarn SY on the winding package WP side, and a piecing device 20 for
piecing a spun yarn SY captured by the suction pipe 18 and a spun yarn SY captured
by the suction mouth 19 to each other.
[0028] A suction air flow is generated at ends of the suction pipe 18 and the suction mouth
19 by a suction flow generating source (not shown), and the yarn end is sucked and
captured. The piecing device 20 includes a clamp section, a cutter section and a splicer
or a knotter (not shown). A spun yarn SY which is draught and spun by the spinning
machine 1 is formed as a winding package WP by the winding device 8.
[0029] In this invention, the yarn slack eliminating devices 7 respectively provided in
the plurality of spinning units U can engage or do not engage the spun yarn SY.
[0030] In this invention, as shown in Figs. 3 and 4, the yarn slack eliminating device 7
includes the yarn slack eliminating roller 21 for winding a spun yarn SY around its
outer periphery and stores the same, the yarn hooking member 22 which coaxially rotates
integrally with or independently from the yarn slack eliminating roller 21 in accordance
with a condition, an upstream guide 23 disposed slightly upstream from the yarn slack
eliminating roller 21, advancing and retreating means (e.g., air cylinder 24) which
advances or retreat the upstream guide 23, a rotating and driving source 25 such as
an electric motor for rotating the yarn slack eliminating roller 21, and a downstream
guide 26 provided downstream from the yarn slack eliminating roller 21.
[0031] The upstream guide 23 is moved forward and backward by the air cylinder 24. When
the upstream guide 23 is in the advance position, the yarn road is held by the upstream
guide 23 so that the spun yarn SY is not engaged with the yarn hooking member 22 in
the yarn slack eliminating device 7. When the upstream guide 23 is the retreat position,
the spun yarn SY moves on the yarn road to a position where the spun yarn SY is engaged
with the yarn hooking member 22 in the yarn slack eliminating device 7 and wound around
the yarn slack eliminating roller 21.
[0032] Of constituent members of the yarn slack eliminating device 7, the yarn slack eliminating
roller 21, the upstream guide 23, the air cylinder 24, the rotating and driving source
25 and the downstream guide 26 are supported by the spinning unit U through a fixing
member such as a bracket 27.
[0033] Fig. 3 shows a concrete example of the yarn slack eliminating device 7, and is a
schematic half sectional perspective view showing an internal structure thereof. Fig.
4A is a schematic vertical sectional view of the yarn slack eliminating device 7.
4B is a schematic transverse sectional view taken along the line 4B-4B as viewed from
the arrow in Fig. 4A.
[0034] As shown in Figs. 3 and 4, the yarn slack eliminating roller 21 is constituted by
a rotary structure RS which is integrally rotated by the rotating and driving source
25. The rotary structure RS includes an inner magnetic pole member 29 connected to
a rotation shaft 28 of the rotating and driving source 25, an outer magnetic pole
member 32 connected to the inner magnetic pole member 29 through a non-magnetic member
31 mounted by a mounting screw 30, and a yarn slack eliminating roller main body 33
fixed to the outer magnetic pole member 32. These members are integrally rotated by
rotation of the rotating and driving source 25.
[0035] If a side of an outer peripheral surface 33a of the yarn slack eliminating roller
main body 33 having the yarn hooking member 22 is defined as a tip end and a side
of the outer peripheral surface 33a of the yarn slack eliminating roller main body
33 connected to the rotating and driving source 25 is defined as a base end, a base
end side tapered portion a, a cylindrical portion b and a tip end side tapered portion
c are arranged from the base end toward the tip end. The base end side tapered portion
a and the tip end side tapered portion c have the largest diameters and are gently
tapered toward the other ends. The cylindrical portion b is tapered to its tip end,
and is continuously connected to both tapered portions seamlessly.
[0036] At the time of the piecing operation by the piecing truck 3, the yarn slack eliminating
device 7 winding the spun yarn SY from the spinning device 5 from the base end of
the yarn slack eliminating roller main body 33 around the outer peripheral surface
33a of the yarn slack eliminating roller main body 33 by the yarn hooking member 22.
After the piecing operation is completed, the spun yarn SY wound and stored around
the outer peripheral surface 33a is released from the tip end of the yarn slack eliminating
roller main body 33 toward the winding device 8 through the yarn hooking member 22.
[0037] In the outer peripheral surface 33a of the yarn slack eliminating roller main body
33, the base end side tapered portion a smoothly moves the supplied and wound spun
yarn SY from a large diameter portion toward a small diameter portion of the base
end side tapered portion a, and the spun yarn SY reaches the intermediate cylindrical
portion b, thereby regularly winding the spun yarn SY around the surface of the intermediate
cylindrical portion b. When releasing the spun yarn SY, the tip end side tapered portion
c prevents the wound spun yarn SY from coming out at a time, and winding the spun
yarn SY from the small diameter portion to the end surface side large diameter portion
sequentially to reliably pull out the spun yarn SY smoothly.
[0038] A magnetic field forming means 34 by an electromagnet includes a stationary annular
exciting coil 35 fixed to the bracket 27 or the like. The inner magnetic pole member
29 is disposed inside 35a of the annular exciting coil 35, and the outer magnetic
pole member 32 is disposed outside 35b of the exciting coil 35.
[0039] The inner magnetic pole member 29 includes an opposed portion 36 which is opposed
along the inside 35a of the annular exciting coil 35, and an inner magnetic pole 37
extending in the axial direction from the opposed portion 36. The outer magnetic pole
member 32 includes an opposed portion 38 opposed along the outside 35b of the exciting
coil 35, and an outer magnetic pole 39 extending in the axial direction from the opposed
portion 38.
[0040] As shown in Fig. 4B, the inner magnetic pole 37 includes eight outward convex portions
40 extending radially outward at equal distances from each other. The outer magnetic
pole 39 includes, for example, eight inward convex portions 41 extending radially
inward at equal distances from each other. Magnetic field forming spaces 42 are formed
between the outward convex portions 40 of the inner magnetic pole 37 and the inward
convex portions 41 of the outer magnetic pole 39.
[0041] The yarn hooking member 22 in the yarn slack eliminating device 7 is assembled such
that the yarn hooking member 22 can rotate independently from a rotation system of
the yarn slack eliminating roller 21. More specifically, the yarn hooking member 22
is integrally provided with a flier shaft 44 which is supported by a bearing means
43 such that the flier shaft 44 can relatively coaxially rotate with the inner magnetic
pole member 29, a flier 45 fixed to the outer end 44a of the flier shaft 44, and an
annular member 46 of hysteresis material extending and positioned in the magnetic
field forming space 42.
[0042] The flier 45 has such a shape that the flier 45 is engaged with the spun yarn SY
(caught on the spun yarn SY) to appropriately curve the spun yarn SY toward the outer
peripheral surface 33a of the yarn slack eliminating roller main body 33.
[0043] In such a structure, the yarn slack eliminating device 7 is operated as follows.
That is, when current is supplied to the exciting coil 35 in the magnetic field forming
means 34, the inner magnetic pole member 29 an and the outer magnetic pole member
31 are excited. A hysteresis annular member 46 which is integrally assembled to the
yarn hooking member 22 such that the hysteresis annular member 46 intersects with
the magnetic field is disposed in a magnetic field forming space 42 formed between
the inner magnetic pole 37 in the inner magnetic pole member 29 and the outer magnetic
pole 39 in the outer magnetic pole member 31. A rotation torque can be generated between
the yarn slack eliminating roller 21 and the rotatable yarn hooking member 22 by the
electromagnet with respect to the yarn slack eliminating roller 21 and the hysteresis
annular member with respect to the yarn hooking member 22.
[0044] Like the concrete embodiment shown in Figs. 3 and 4, the exciting coil 35 is handled
as a stationary system, the inner magnetic pole member 29 and the outer magnetic pole
member 31 are disposed with respect to the exciting coil 35, and they are rotated
integrally with the yarn slack eliminating roller 21. If current flows through the
exciting coil 35 in such a state, the magnetic field rotates together with the yarn
slack eliminating roller 21. If the hysteresis annular member which is integral with
the yarn hooking member 22 is disposed in the magnetic field, a relative rotation
torque is obtained in the yarn hooking member 22 with respect to the rotating yarn
slack eliminating roller 21.
[0045] This rotation torque is varied depending upon the magnitude of the magnetic field.
Thus, if voltage or current given to the exciting coil 35 is varied, an arbitrary
rotation torque can be obtained. As a result, if a preset control value is input,
an arbitrary rotation torque can be set with a simple operation.
[0046] In the above structure, if a high-end control device is provided, torques of a plurality
of spindles can be changed in unison. Further, it is possible to change the rotation
torque during spinning out operation and thus, it is possible to positively change
tension during the winding operation. If means for measuring the actual yarn tension
during the spinning out operation, a feedback control based on a signal of the means
can be performed, Thus, when the tension is varied due to some reason such as disturbance,
it is possible to change the magnetic field in real time, and to return the tension
to any tension.
[0047] The operation of the spinning machine 1 having the above-described structure will
be explained. Each spinning unit U of the spinning machine 1 sends out the fiber bundle
Y to the spinning device 5 by the draft device 4. The spun yarn SY spun and produced
in the spinning device 5 is supplied to the downstream by the yarn feeding device
6, passes through the cutter device 16 and the yarn clearer 17, and finally feed the
winding device 8 through the yarn slack eliminating device 7, and is winding as the
package WP.
[0048] When the yarn clearer 17 of any of the spinning units U detects a defect of the spun
yarn SY, the unit controller (not shown) of that spinning unit U cut the spun yarn
SY using the cutter device 16, and substantially at the same time, rotations of the
pair of back rollers 9 and the pair of side rollers 10 of the draft device 4 are stopped.
The fiber bundle Y is yanked and cut between the stopped pair of third rollers 10
and the rotating pair of middle rollers 12, and the spun yarn SY downstream from the
cut portion are sucked and removed by the suction means (not shown).
[0049] The unit controller of the spinning unit U sends a yarn piecing request signal to
the piecing truck 3, and the piecing truck 3 moves to a position opposed to that spinning
unit U and stops. Then, the unit controller starts rotating the yarn slack eliminating
roller 21 of the yarn slack eliminating device 7 at appropriate timing. At the same
time, the unit controller moves the upstream guide 23 of the yarn slack eliminating
device 7 forward by the air cylinder 24, and holds the yarn road so that a spun yarn
SY which is spun next is not engaged with the yarn hooking member 22 of the yarn slack
eliminating device 7 when it is unnecessary.
[0050] If the suction pipe 18 of the piecing truck 3 is turned upward, the driving operations
of the draft device 4 and the spinning device 5 are started substantially in synchronization
with the upward turning, and the spun yarn SY which is spun out from the spinning
device 5 is sucked and captured by the suction pipe 18. The suction mouth 19 of the
piecing truck 3 is turned downward on the side of the winding device 7, and the yarn
end wound around the package WP is sucked and captured. The suction pipe 18 and the
suction mouth 19 guide the sucked yarn ends to the piecing device 20 and carry out
the piecing operation.
[0051] Immediately before the piecing operation is started by the piecing device 20, the
air cylinder 24 retreats in the yarn slack eliminating device 7, and the upstream
guide 23 is moved to the retreat position. The yarn road of the spun yarn SY is changed
such that the yarn road is superposed on the rotation locus of the flier 45 in the
yarn hooking member 22. As a result, the spun yarn SY is wound around the outer peripheral
surface 33a of the yarn slack eliminating roller 21 by the flier 45.
[0052] That is, the spinning out operation of the spun yarn SY from the spinning device
5 is continued also during the piecing operation at the piecing device 20. Thus, if
it is left as it is, a large amount of spun yarn SY stays upstream of the piecing
device 20. The yarn slack eliminating device 7 winds the spun yarn SY around the yarn
slack eliminating roller 21 during the piecing operation by the piecing device 20,
thereby preventing the slack and residence of the spun yarn SY, and realizing smooth
piecing operation and spinning resuming operation.
[0053] As described above, the flier 45 and the flier shaft 44 can rotate independently
from the yarn slack eliminating roller 21, but the flier 45 rotates integrally with
the yarn slack eliminating roller 21 unless a load greater than a given magnification
(load overcoming a hysteresis torque acting on the electromagnet and the hysteresis
annular member) is applied by a mechanism comprising the electromagnet and the hysteresis
annular member 46. During the piecing operation, downstream side of the spun yarn
SY is stopped, and a load applied to the flier 45 is small. Thus, the flier 45 rotates
integral with the yarn slack eliminating roller 21 and winds the spun yarn SY around
the outer periphery of the yarn slack eliminating roller 21.
[0054] After the piecing operation by the piecing device 20 is completed, the package WP
is rotated by a winding drum in the winding device 8, and the winding operation of
the spun yarn SY is resumed.
[0055] The spun yarn SY which is spun out from the spinning device 5 is wound around the
outer peripheral surface 33a of the yarn slack eliminating roller 21 which keeps rotating
while the winding operation is resumed from the start of the piecing operation by
the piecing device 20. If the winding operation by the winding device 8 is resumed,
since a ratio of a feeding out speed of the yarn feeding device 6 and a winding speed
of the winding device 8 is set such that appropriate tension is given to the spun
yarn SY, a speed of yarn pulled out from the yarn slack eliminating roller 21 is faster
than a speed of yarn wound around the yarn slack eliminating roller 21. Therefore,
the flier 45 of the yarn slack eliminating device 7 rotates independently from the
yarn slack eliminating roller 21 which keeps rotating in the winding direction, and
the spun yarn SY wound and stored around the yarn slack eliminating roller 21 is gradually
released. The tension given to the spun yarn SY at that time is determined by the
relative rotation torque between the yarn hooking member 22 and the yarn slack eliminating
roller 21 of the invention.