YARN MONITORING DEVICE, YARN WINDING MACHINE, AND AUTOMATIC
WINDER
BACKGROUND OF THE INVENTION
5 1. Field of the Invention
The present invention mainly relates to a yarn
monitoring device adapted to monitor a travelling yarn.
2. Description of the Related Art
10 Conventionally, a yarn winding machine such as a
spinning machine, an automatic winder, and the like
includes an optical yarn monitoring device adapted to
monitor a yarn being wound. The yarn monitoring device
irradiates a travelling yarn with light and receives
15 transmitted light that has transmitted through the yarn or
reflected light that has been reflected by the yarn with
a light receiving element such as a photodiode to monitor
a thickness of the yarn, and the like in real time and detect
a yarn defect (portion with abnormality in quality of the
20 yarn).
JP2000-327226A and JP2007-131974A disclose this type
of optical yarn monitoring device.
During winding of the yarn, a temperature of the yarn
monitoring device may be lowered when an airflow is
25 generated as a result of the travelling of the yarn, or the
temperature of the yarn monitoring device may rise when a
friction heat is generated as a result of the travelling
of the yarn. A light projecting element and a light
receiving element are influenced by such a temperature
30 change, and hence properties (light amount to be projected,
current to be output, and the like) thereof change. In this
2
regard, JP2000-327226A and JP2007-131974A disclose a
process of correcting an output signal and the like of the
light receiving element in view of the temperature change
during the travelling of the yarn. However, in
5 JP2000-327226A and JP2007-131974A, the timing to carry out
such a correction is not described in detail.
BRIEF SUMMARY OF THE INVENTION
The present invention has been made in view of the
10 above circumstances, and a main object thereof is to provide
a yarn monitoring device, a yarn winding machine, and an
automatic winder which carry out a process of correcting
a thickness of a yarn at an appropriate timing in view of
a temperature change during travelling of the yarn.
15 The problems to be solved by the present invention
are as described above, and now, the means for solving such
problems will be described.
According to a first aspect of the present invention,
a yarn monitoring device having the following configuration
20 is provided. Specifically, the yarn monitoring device
includes an optical yarn thickness detecting section and
a correcting section. The yarn thickness detecting
section is adapted to detect a yarn thickness of a
travelling yarn. The correcting section carries out a
25 first confirmation process of confirming the yarn thickness
detected by the yarn thickness detecting section, and
carries out a first correction of correcting the yarn
thickness when the yarn thickness confirmed in the first
confirmation process satisfies a predetermined increasing
30 condition, in a predetermined first period. The
correcting section also carries out a second confirmation
3
process of confirming the yarn thickness detected by the
yarn thickness detecting section, and carries out a second
correction of correcting the yarn thickness when the yarn
thickness confirmed in the second confirmation process
5 satisfies a predetermined reducing condition, in a
predetermined second period different from the
predetermined first period.
According to a second aspect of the present invention,
a yarn winding machine having the following configuration
10 is provided. Specifically, the yarn winding machine
includes a winding section, a yarn thickness detecting
section, and a correcting section. The winding section is
adapted to wind a yarn to form a package. The yarn thickness
detecting section is adapted to detect a yarn thickness of
15 a travelling yarn. The correcting section carries out a
first confirmation process of confirming the yarn thickness
detected by the yarn thickness detecting section, and
carries out a first correction of correcting the yarn
thickness when the yarn thickness confirmed in the first
20 confirmation process satisfies a predetermined increasing
condition, in a predetermined first period, and carries out
a second confirmation process of confirming the yarn
thickness detected by the yarn thickness detecting section,
and carries out a second correction of correcting the yarn
25 thickness when the yarn thickness confirmed in the second
confirmation process satisfies a predetermined reducing
condition, in a predetermined second period different from
the predetermined first period.
An automatic winder serving as the above-described
30 automatic winder preferably has the following
configuration. Specifically, the automatic winder
4
includes a yarn travelling length detecting section adapted
to detect a yarn travelling length that is a length in which
the yarn has travelled. The winding section winds the yarn
while changing a winding speed at least temporarily. The
5 correcting section carries out the first confirmation
process and determines whether the yarn thickness confirmed
in the first confirmation process satisfies the
predetermined increasing condition every time the yarn
travels a first predetermined length, and carries out the
10 second confirmation process and determines whether the yarn
thickness confirmed in the second confirmation process
satisfies the predetermined reducing condition every time
the yarn travels a second predetermined length.
15 BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view illustrating an overall
configuration of an automatic winder including a yarn
monitoring device according to one embodiment of the
present invention;
20 FIG. 2 is a side view of a winding unit including the
yarn monitoring device;
FIG. 3 is a block diagram illustrating an electrical
configuration of the yarn monitoring device;
FIG. 4 is a graph illustrating a relationship of a
25 yarn travelling length and a voltage of an electrical signal
(yarn thickness);
FIG. 5 is a graph illustrating a relationship of the
yarn travelling length, the yarn thickness, and a
correction amount;
30 FIG. 6 is a flowchart illustrating a first half of
a process of correcting the yarn thickness in view of a
5
temperature change and the like during the travelling of
the yarn; and
FIG. 7 is a flowchart illustrating a second half of
the process of correcting the yarn thickness in view of the
5 temperature change and the like during the travelling of
the yarn.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Next, an embodiment of the present invention will be
10 described with reference to the drawings.
As illustrated in FIG. 1, an automatic winder (yarn
winding machine) 1 includes as main components a plurality
of winding units (yarn winding units) 10 arranged side by
side, and a machine control section 11 arranged at one end
15 in a direction in which the winding units 10 are arranged.
The machine control section 11 includes a display
device 12 capable of displaying information associated with
each winding unit 10, an instruction input section 13 for
an operator to input various types of instructions with
20 respect to the machine control section 11, and the like.
The operator of the automatic winder 1 can check various
types of displays displayed on the display device 12, and
can also appropriately operate the instruction input
section 13 to collectively manage the plurality of winding
25 units 10 with the machine control section 11.
Each winding unit 10 illustrated in FIGS. 1 and 2 is
configured to unwind a yarn from a yarn supplying bobbin
20 and to rewind the yarn around a winding bobbin 22. The
winding bobbin 22 with a yarn 21 wound therearound is
30 referred to as a package 23. In the following description,
“upstream in the yarn travelling direction” and “downstream
6
in the yarn travelling direction” respectively refer to
upstream and downstream when seen in the travelling
direction of the yarn 21.
As illustrated in FIG. 2, the winding unit 10 includes
5 a main body frame 24, a yarn supplying section 25, and a
winding section 26 as main components.
The main body frame 24 is arranged at a side of the
winding unit 10. The majority of the components of the
winding unit 10 is directly or indirectly supported by the
10 main body frame 24.
The yarn supplying section 25 is configured to be able
to hold the yarn supplying bobbin 20, adapted to supply the
yarn 21, in a substantially upright state. The winding
section 26 includes a cradle 28 and a winding drum 29.
15 The cradle 28 rotatably supports the winding bobbin
22. The cradle 28 is also configured to allow a peripheral
surface of the supporting winding bobbin 22 to make contact
with a peripheral surface of the winding drum 29. The
winding drum 29 is arranged to face the winding bobbin 22,
20 and is configured to be rotatably driven by a winding drum
drive motor (not illustrated). A traverse groove (not
illustrated) having a reciprocating spiral shape for
traversing the yarn 21 being wound around the winding bobbin
22 is formed on the outer peripheral surface of the winding
25 drum 29.
The winding bobbin 22 is driven and rotated by
rotatably driving the winding drum 29 with the outer
peripheral surface of the winding bobbin 22 in contact with
the winding drum 29. Thus, the yarn 21 unwound from the
30 yarn supplying bobbin 20 can be wound around the winding
bobbin 22 while being traversed by the traverse groove. The
7
component for traversing the yarn 21 is not limited to the
winding drum 29, and instead of the winding drum 29, for
example, an arm-type traverse device adapted to guide the
yarn 21 with a traverse guide driven in a reciprocating
5 manner at a predetermined traverse width can be adopted.
When the arm type traverse device is adopted, the winding
bobbin 22 is preferably rotatably driven directly.
Each winding unit 10 includes a unit control section
30. The unit control section 30 is configured by hardware
10 such as CPU, ROM, and RAM, and software such as a control
program stored in the ROM or the RAM. With the cooperative
operation of the hardware and the software, each component
of the winding unit 10 is controlled. The unit control
section 30 of each winding unit 10 is configured to be
15 communicable with the machine control section 11. Thus,
the operation of each winding unit 10 can be intensively
managed by the machine control section 11.
The winding unit 10 has a configuration in which an
unwinding assisting device 31, a tension applying device
20 32, a yarn joining device 33, and a yarn monitoring device
6 are arranged in this order from the upstream in the
travelling direction of the yarn on a yarn travelling path
between the yarn supplying section 25 and the winding
section 26.
25 The unwinding assisting device 31 includes a
regulating member 35 adapted to make contact with a portion
(balloon) bulged out to the outer side when the yarn 21
unwound from the yarn supplying bobbin 20 is swung around
by a centrifugal force. The contact of the regulating
30 member 35 to the balloon suppresses the yarn 21 from being
swung around in excess, and maintains the balloon to a
8
prescribed size, thus enabling the unwinding of the yarn
21 from the yarn supplying bobbin 20 to be carried out under
a prescribed tension.
The tension applying device 32 is adapted to apply
5 a predetermined tension on the travelling yarn 21. The
tension applying device 32 of the present embodiment may
be a gate-type tension applying device in which movable comb
teeth are arranged with respect to fixed comb teeth. The
tension applying device 32 applies an appropriate tension
10 on the yarn 21 by passing the yarn 21 while being bent between
the comb teeth in a meshed state. Other than the gate-type
tension applying device, a disc-type tension applying
device, for example, may be adopted for the tension applying
device 32.
15 The yarn joining device 33 is configured to join (yarn
joining operation) a yarn (lower yarn) from the yarn
supplying bobbin 20 and a yarn (upper yarn) from the winding
bobbin 22 when the yarn 21 between the yarn supplying bobbin
20 and the winding bobbin 22 is disconnected such as, for
20 example, when the yarn is cut with a cutting device (cutter)
16, to be described later. The configuration of the yarn
joining device 33 is not particularly limited, but a
pneumatic splicer that twists the yarn ends with a whirling
airflow generated by compressed air can be adopted, or a
25 mechanical knotter and the like can be adopted. An upper
yarn suction pipe 44 sucks and catches the yarn end from
the winding bobbin 22, and guides the yarn end to the yarn
joining device 33. A lower yarn suction pipe 45 sucks and
catches the yarn end from the yarn supplying bobbin 20, and
30 guides the yarn end to the yarn joining device 33.
The yarn monitoring device 6 monitors the state
9
(thickness, mixture of foreign substance such as color yarn,
polypropylene, and the like) of the travelling yarn 21, and
detects a yarn defect contained in the yarn 21. The yarn
monitoring device 6 can detect a yarn travelling speed of
5 the travelling yarn 21. The yarn monitoring device 6 also
includes the cutter 16 adapted to cut the yarn 21 when the
yarn monitoring device 6 detects the yarn defect. The
detailed configuration of the yarn monitoring device 6 will
be described later.
10 Now, a description on an operation of when the yarn
defect and the like are detected by the yarn monitoring
device 6 will be briefly made with reference to FIG. 2.
When the yarn defect and the like are detected in the
monitoring yarn, the yarn monitoring device 6 activates the
15 cutter 16 to cut the yarn 2 1, and also transmits a yarn defect
detection signal to the unit control section 30. The yarn
21 located downstream of the cut area is once wound into
a package 23. The yarn 21 wound into the package 23 in this
case includes a portion of yarn defect and the like detected
20 by the yarn monitoring device 6. After receiving the yarn
defect detection signal, the unit control section 30 stops
the winding of the yarn 21 by the winding section 26.
The lower yarn suction pipe 45 sucks and catches the
yarn end supplied from the yarn supplying bobbin 20, and
25 guides the yarn end to the yarn joining device 33. Before
or after this, the upper yarn suction pipe 44 sucks and
catches the yarn end wound into the package 23, and guides
the yarn end to the yarn joining device 33. In this case,
the portion of yarn defect and the like wound into the
30 package 23 is sucked and pulled out by the upper yarn suction
pipe 44.
10
The yarn joining device 33 joins the yarn ends guided
by the upper yarn suction pipe 44 and the lower yarn suction
pipe 45. Thus, after the portion including the yarn defect
and the like is removed, the yarn 21 cut by the cutter 16
5 is again connected.
After the yarn joining operation by the yarn joining
device 33 is completed, the unit control section 30 resumes
the winding of the yarn 21 by the winding section 26.
According to the above operations, the yarn defect and the
10 like detected by the yarn monitoring device 6 can be removed,
and the winding of the yarn 21 into the package 23 can be
resumed.
Furthermore, in the present embodiment, the unit
control section 30 carries out a disturb control (period
15 control) to prevent generation of ribbon winding (a state
in which the yarn 21 is concentrated at one area and wound
in an overlapping manner). Specifically, the unit control
section 30 controls the winding drum drive motor (not
illustrated) and periodically changes the rotation speed
20 of the winding drum 29 to slide the package 23 and the winding
drum 29, thus changing the winding speed. Therefore, in
the present embodiment, the yarn travelling speed of the
yarn 21 is not constant. Furthermore, since the package
23 and the winding drum 29 slide, an accurate yarn
25 travelling speed cannot be detected even if the rotation
speed of the winding drum 29 is used. Moreover, the yarn
travelling speed is not constant even if the disturb control
is not carried out. For example, when forming a cone-shaped
package, the yarn travelling speed significantly changes
30 depending on whether the yarn is wound around the large
diameter side of the package or the small diameter side of
11
the package, and hence it is difficult to detect an accurate
yarn travelling speed based solely on the rotation speed
of the winding drum 29.
Next, a description will be made on the details of
5 the yarn monitoring device 6, in particular, the electrical
configuration with reference to FIG. 3. FIG. 3 is a block
diagram illustrating an electrical configuration of the
yarn monitoring device 6.
As illustrated in FIG. 3, the yarn monitoring device
10 6 includes an optical sensor unit (yarn thickness detecting
section) 50 and a yarn monitoring control section 60.
The sensor unit 50 can measure the state of the yarn
21. The sensor unit 50 includes a drive circuit 51, a light
projecting section 52, a light receiving section 53, an
15 amplifier 54, a high-pass filter 55, and an amplification
circuit 56. The cutter 16 is attached to a housing of the
sensor unit 50. In the present embodiment, a total of two
sets of light projecting section 52 and light receiving
section 53 are arranged, where each set is arranged at a
20 different position on the yarn travelling path. In other
words, the light projecting section 52 includes a first
light projecting section arranged on the upstream of the
yarn travelling path, and a second light projecting section
arranged on the downstream of the yarn travelling path. The
25 light receiving section 53 includes a first light receiving
section arranged on the upstream of the yarn travelling path,
and a second light receiving section arranged on the
downstream of the yarn travelling path.
The light projecting section 52 includes a light
30 emitting element configured by a light emitting diode (LED).
The light projecting section 52 irradiates a space
12
(slit-shaped recess of FIG. 3 ) , through which the yarn 21
travels, with light at a light amount corresponding to a
drive voltage input from the drive circuit 51. The drive
voltage generated by the drive circuit 51 is determined
5 based on an electrical signal input from the yarn monitoring
control section 60.
The light receiving section 53 is arranged on an
opposite side of the light projecting section 52 with a yarn
path therebetween. The light receiving section 53
10 includes a light receiving element configured by a
photodiode and the like. The light receiving section 53
receives transmitted light of the light radiated from the
light projecting section 52 onto the yarn 21, and outputs
the electrical signal (output voltage or output current)
15 corresponding to the light receiving amount. The
electrical signal changes according to the shape
(cross-sectional shape) of the yarn 21 present in a
detection region 70. The transmitted light referred to
herein is the light that reached the light receiving section
20 53 when the light output from the light projecting section
52 is partially shielded by the presence of the yarn 21.
In other words, the transmitted light is the light that
passed through the yarn 21. The detection region 70 is a
region, in the slit-like recess, where the light from the
25 light projecting section 52 collides, and is a region where
the yarn 21 can be detected according to the light receiving
amount of the light receiving section 53.
The electrical signal output by the light receiving
section 53 is amplified by the amplifier 54 and is also
30 subjected to an inversion process. Thus, conversion is
made such that the electrical signal output by the amplifier
13
54 becomes smaller as the light receiving amount of the
light receiving section 53 is greater (i.e., narrower the
yarn 21). A signal of a predetermined high frequency in
the electrical signal output by the amplifier 54 is
5 extracted in the high-pass filter 55, and the electrical
signal is again amplified by the amplification circuit 56.
The sensor unit 50 detects the thickness of the yarn 21 in
such a manner. The sensor unit 50 outputs the electrical
signal indicating the detection result of the yarn
10 thickness to the yarn monitoring control section 60.
The yarn monitoring control section 60 includes a
yarn travelling length detecting section 61 and a
correcting section 62. The yarn travelling length
detecting section 61 detects the length (yarn travelling
15 length) of the yarn 21 travelling through the detection
region 70 by obtaining, from the thickness unevenness and
the like of the yarn 2 1, to what extent the electrical signal
output from one light receiving section 53 is delayed with
respect to the electrical signal output from the other light
20 receiving section 53. The correcting section 62 corrects
the yarn thickness in view of the change in properties and
the like of the light projecting section 52 and the light
receiving section 53 caused by temperature change (to be
described in detail later). The sensor unit 50 and the yarn
25 monitoring control section 60 are arranged for every
automatic winder 1, so that the correction of the yarn
thickness is carried out for every automatic winder 1.
The cutter 16 described above is arranged in
proximity to the detection region 70 formed in the housing
30 of the sensor unit 50. The cutter 16 includes a cutting
blade (not illustrated) driven by a solenoid, for example.
14
The cutter 16 is electrically connected to the yarn
monitoring control section 60, and is able to cut the yarn
21 based on a cutting signal output by the yarn monitoring
control section 60.
5 Next, a description will be made on the correction
carried out by the correcting section 62 of the yarn
monitoring device 6 with reference to FIGS. 4 to 7.
In the graph of FIG. 4, a horizontal axis indicates
a yarn travelling length, and a vertical axis indicates a
10 voltage (i.e., yarn thickness) of an electrical signal
input from the sensor unit 50 to the yarn monitoring control
section 60. Hereinafter, the graph will be described in
time series. At a time point where the yarn travelling
length is at a left end, the winding of the yarn 21 has not
15 started yet, and the yarn 21 is not present in the detection
region 70. Therefore, the voltage of when the yarn
travelling length is at the left end corresponds to a
voltage (initial adjustment value of FIG. 5) output
regardless of the presence/absence of the yarn 21.
20 Thereafter, the upper yarn suction pipe 44 and the
lower yarn suction pipe 45 guide the yarn ends to the yarn
joining device 33 to insert the yarn 21 into the detection
region 70. In the graph of FIG. 4, after the yarn 21 is
inserted into the detection region 70, the yarn 21 is
25 shielded by light and thus the voltage of the electrical
signal becomes high. Since the yarn 21 is not travelling
at this stage, the yarn thickness does not change, and hence
the voltage of the electrical signal is constant.
Thereafter, the yarn joining device 33 performs the
30 yarn joining operation, and then the travelling of the yarn
21 is started. In the graph of FIG. 4, after the start of
15
the travelling of the yarn 21, the voltage of the electrical
signal changes according to the thickness unevenness and
the like of the yarn 21.
The correcting section 62 obtains a “yarn reference
5 thickness”, which is a value obtained by subtracting the
initial adjustment value described above from an average
of the yarn thicknesses (voltages of electrical signals)
from the start of the travelling of the yarn 21 until the
yarn 21 travels a predetermined length (25 m in the present
10 embodiment) (see FIG. 5 ) . The yarn reference thickness may
be obtained from the average of the yarn thicknesses from
the start of the travelling of the yarn 21 until elapse of
a predetermined time. The predetermined length and the
predetermined time in obtaining the yarn reference
15 thickness may always be constant, or a value corresponding
to the winding conditions (type, winding speed, and the like
of yarn 21) may be used.
After the yarn reference thickness is obtained, the
correcting section 62 obtains (calculates) a yarn average
20 thickness. The yarn average thickness is the average
(moving average) of the yarn thicknesses of the yarn 21 at
a predetermined length or predetermined time in the past.
The yarn average thickness is a value including an
adjustment value, as opposed to the yarn reference
25 thickness. In the present embodiment, the average of the
yarn thicknesses of 25 m in the past, which is the same as
the yarn reference thickness, is assumed as the yarn average
thickness. The predetermined length or the predetermined
time in calculating the yarn reference thickness are
30 preferably the same but may be different from the
predetermined length or the predetermined time in
16
calculating the yarn average thickness. Therefore, at the
start of the calculation of the yarn average thickness (L0
of FIG. 4 ) , the (yarn reference thickness + initial
adjustment value) and the yarn average thickness are equal.
5 In the present embodiment, the correcting section 62
updates the yarn average thickness every time the yarn 21
travels 5 m.
The correcting section 62 starts to correct the yarn
thickness after the start of the calculation of the yarn
10 average thickness. Hereinafter, a description will be
made on the correction carried out by the correcting section
62 with reference to FIGS. 6 and 7. FIGS. 6 and 7 are
flowcharts illustrating a process of correcting the yarn
thickness in view of the temperature change and the like
15 during the travelling of the yarn.
The correcting section 62 first acquires the yarn
travelling length detected by the yarn travelling length
detecting section 61 (S101). Then, the correcting section
62 waits until the acquired yarn travelling length is an
20 integral multiple of a first predetermined length (5 m)
(S102). The first predetermined length is a period for
carrying out a correction of the yarn thickness
(hereinafter referred to as first correction) when the
detected yarn thickness is increased (including a case in
25 which the voltage of the electrical signal is increased by
the temperature change). In other words, the correcting
section 62 determines whether or not to carry out the first
correction every time the yarn 21 travels the first
predetermined length. Furthermore, the correcting
30 section 62 carries out a confirmation process (first
confirmation process) of confirming the yarn thickness and
17
determines whether the yarn thickness confirmed in the
first confirmation process satisfies a predetermined
increasing condition every time the yarn 21 travels the
first predetermined length. The period of the first
5 correction is not limited to the yarn travelling length,
and may be carried out every predetermined time (first
predetermined time).
When the yarn travelling length becomes an integral
multiple of the first predetermined length (5, 10, 15 m,
10 and the like), the correcting section 62 obtains the yarn
average thickness as described above, and determines
whether or not the yarn average thickness is greater than
the yarn average thickness of one period before (i.e., 5
m before) (S103). When the yarn average thickness of one
15 period before does not exist or is zero (immediately after
the start of the travelling of the yarn 21, and the like),
the yarn average thickness obtained this time is stored,
and the process is terminated.
When the yarn average thickness obtained this time
20 is greater than the yarn average thickness of one period
before, the correcting section 62 turns ON a first
correction execution flag (S104), and proceeds to the next
process. When the yarn average thickness obtained this
time is smaller than or equal to the yarn average thickness
25 of one period before, the correcting section 62 proceeds
to the next process without turning ON the first correction
flag.
Next, the correcting section 62 determines whether
or not the acquired yarn travelling length has reached a
30 second predetermined length (35 m) (S105). The second
predetermined length is a period for carrying out a
18
correction of the yarn thickness (hereinafter referred to
as second correction) when the yarn thickness is reduced
(including a case in which the voltage of the electrical
signal is reduced by the temperature change). In other
5 words, the correcting section 62 determines whether or not
to carry out the second correction every time the yarn 21
travels the second predetermined length. Furthermore, the
correcting section 62 carries out a confirmation process
(second confirmation process) of confirming the yarn
10 thickness and determines whether the yarn thickness
confirmed in the second confirmation process satisfies a
predetermined reducing condition every time the yarn 21
travels the second predetermined length. The period of the
second correction is not limited to the yarn travelling
15 length, and may be carried out every predetermined time
(second predetermined time).
When the yarn travelling length has reached
(exceeded) the second predetermined length, the correcting
section 62 determines whether or not the yarn average
20 thickness obtained this time is smaller than the yarn
average thickness of one period before (i.e., 35 m before)
(S106). When the yarn average thickness obtained this time
is smaller than the yarn average thickness one period before,
the correcting section 62 turns ON a second correction
25 execution flag (S107), and proceeds to the next process.
When the yarn average thickness obtained this time is
greater than the yarn average thickness of one period before,
the correcting section 62 proceeds to the next process
without turning ON the second correction flag. In S106 and
30 S107, whether or not the yarn average thickness of the
current second period is continuously reduced may be
19
determined, and the second correction execution flag may
be turned ON if the yarn average thickness is continuously
reduced.
When the determination of S106 is carried out, the
5 correcting section 62 clears the value of the yarn
travelling length (S108). Accordingly, the yarn
travelling length is again counted from zero.
The correcting section 62 then determines whether or
not the first correction execution flag or the second
10 correction execution flag is turned ON (S109 of FIG. 7 ) .
When neither of the correction execution flags is turned
ON, the correcting section 62 terminates the process. When
one of the correction execution flags is turned ON, the
correcting section 62 acquires the yarn reference thickness
15 obtained at the start of the travelling of the yarn 21
(S110).
Next, the correcting section 62 calculates a new
correction amount (S111). Specifically, as illustrated in
FIG. 5, a correction adjustment value is calculated by
20 subtracting the yarn reference thickness from the yarn
average thickness obtained this time. Describing this
computation, the yarn reference thickness more or less
clearly indicates the yarn thickness since the yarn
reference thickness is obtained in a situation where
25 influence and the like of the temperature change is small.
Therefore, the adjustment value (correction adjustment
value) that takes into consideration the influence of the
current temperature change, the change in the fiber amount
of the yarn 21, or the like can be calculated by subtracting
30 the yarn reference thickness from the yarn average
thickness. Furthermore, the fluctuation amount
20
(correction amount) of the voltage by the influence of
temperature change, the change in the fiber amount of the
yarn 21, or the like is obtained by subtracting the initial
adjustment value from the correction adjustment value.
5 The correction amount is positive in the example
illustrated in FIG. 5, but may be negative depending on the
situation.
After the computation described above, the
correcting section 62 determines whether or not an absolute
10 value of the correction amount is greater than a
predetermined threshold value (S112). When the absolute
value of the correction amount is greater than the
predetermined threshold value, the correcting section 62
determines that the changing amount of the detection value
15 by the influence of temperature change becomes large and
the influence on the gain becomes too large, and thus
operates the cutter 16 to cut the yarn 21 (S113).
On the other hand, when the absolute value of the
correction amount is smaller than or equal to the
20 predetermined threshold value, the correcting section 62
corrects the yarn thickness based on the calculated
correction amount (S114). Therefore, when the first
correction execution flag is turned ON, the first
correction is carried out. For example, when the yarn
25 travelling length of FIG. 5 is 0 m to 35 m (first count),
the yarn average thickness is gradually increased compared
to 5 m before, and thus the correction amount is corrected
every first predetermined length (every 5 m ) . When the
second correction execution flag is turned ON, the second
30 correction is carried out. For example, when the yarn
travelling length of FIG. 5 is 35 m (second and third counts),
21
the yarn average thickness is reduced compared to the yarn
average thickness 35 m before, and thus the correction
amount is corrected. When both the first correction
execution flag and the second correction execution flag are
5 turned ON, one of the corrections defined in advance is
carried out.
Thus, in the present embodiment, the period for
determining whether or not the correction is necessary
differs between when the increased amount of the detected
10 yarn thickness is greater than or equal to a predetermined
amount (when the first correction is carried out) and when
the reduced amount of the detected yarn thickness is greater
than or equal to a predetermined amount (when the second
correction is carried out). This is due to the following
15 reasons. That is, a case in which the yarn thickness is
increased includes a situation where cotton fly is
entangled around the yarn 21 at the stage of generating the
yarn 21, and the like, and the yarn thickness rapidly
becomes large in such a situation. On the other hand, when
20 the yarn thickness becomes thick by the influence of
temperature change, the detection value of the sensor unit
50 (i.e., detected yarn thickness) gradually changes.
Therefore, whether the yarn thickness is actually increased
or the yarn thickness seems to be increased by the influence
25 of temperature change can be distinguished in a short time.
Thus, whether or not the yarn thickness is increased can
be frequently (shorter period) determined. A case in which
the yarn thickness is reduced includes a situation where
fibers contained in the yarn 21 at the stage of generating
30 the yarn 21 is gradually removed, and the like, and the yarn
thickness gradually becomes small in such a situation. On
22
the other hand, when the yarn thickness is reduced by the
influence of temperature change, the detection value of the
sensor unit 50 (i.e., detected yarn thickness) gradually
changes. Therefore, when the yarn thickness is reduced,
5 the period needs to be made long to distinguish whether the
yarn thickness is actually reduced, or the yarn thickness
seems to be reduced by the influence of temperature change.
In view of the above, the period of the first correction
is made shorter than the period of the second correction
10 in the present embodiment.
When the yarn is disconnected (yarn breakage or yarn
cut by the cutter) after the start of the correction as
illustrated in FIG. 4, the initial adjustment value is
corrected. Furthermore, the yarn reference thickness can
15 be calculated by the yarn 21 travelling a length (25 m in
the present embodiment) corresponding to the calculation
of the yarn reference thickness from the start of the
travelling of the yarn 21. Therefore, the correction of
the yarn thickness is again resumed at this timing.
20 As described above, the yarn monitoring device 6 of
the present embodiment includes the optical sensor unit 50,
and the correcting section 62. The sensor unit 50 detects
the yarn thickness of the travelling yarn 21. The
correcting section 62 carries out a first correction of
25 correcting the yarn thickness at a predetermined period
(when correction is required) based on the increased amount
of the yarn thickness detected by the sensor unit 50, and
a second correction of correcting the yarn thickness at a
period different from the first correction (when correction
30 is required) based on the reduced amount of the yarn
thickness detected by the sensor unit 50.
23
Thus, since the behavior in the change of the yarn
thickness differs between when the yarn thickness is
increased and when the yarn thickness is reduced, the period
corresponding to each case is set so that the yarn thickness
5 can be corrected at an appropriate timing corresponding to
the change in the yarn thickness while taking into
consideration the temperature change during the travelling
of the yarn.
The yarn monitoring device 6 of the present
10 embodiment includes the yarn travelling length detecting
section 61 adapted to detect the yarn travelling length that
is the length in which the yarn 21 has travelled. The
correcting section 62 determines whether or not to carry
out the first correction every time the yarn 21 travels the
15 first predetermined length, and determines whether or not
to carry out the second correction every time the yarn 21
travels the second predetermined length, based on the yarn
travelling length detected by the yarn travelling length
detecting section 61.
20 The timing of correction is thus determined based on
the yarn travelling length, so that the yarn thickness can
be more accurately corrected compared to the case in which
the timing of correction is determined based on time.
Moreover, in the yarn monitoring device 6 of the
25 present embodiment, the correcting section 62 obtains, as
a yarn reference thickness, a value based on the average
of the yarn thicknesses from the start of the travelling
of the yarn 21 until the yarn 21 travels a predetermined
length, and carries out the first correction or the second
30 correction based on the increased amount or the reduced
amount from the yarn reference thickness.
24
Thus, the influence of temperature change is assumed
to be small for a predetermined time from the start of the
travelling of the yarn 21, so that the influence of
temperature change and the like can be accurately estimated
5 by taking the average of the yarn thickness (yarn reference
thickness) acquired during that time as a reference.
Therefore, the yarn thickness can be more accurately
corrected.
Furthermore, in the present embodiment, the winding
10 section 26 winds the yarn 21 while changing the winding
speed at least temporarily to carry out the disturb control.
The correcting section 62 determines whether or not to carry
out the first correction every time the yarn 21 travels the
first predetermined length, and determines whether or not
15 to carry out the second correction every time the yarn 21
travels the second predetermined length, based on the yarn
travelling length detected by the yarn travelling length
detecting section 61.
Accordingly, even with the automatic winder adapted
20 to wind the yarn 21 while changing the winding speed, the
yarn thickness can be corrected at an appropriate timing
by carrying out the correction based on the yarn travelling
length.
The preferred embodiment of the present invention has
25 been described above, but the above-described
configuration may be modified as below.
In the above-described embodiment, the yarn
monitoring device 6 has the voltage inverted by the
amplification circuit 56, and hence the yarn thickness
30 becomes larger as the voltage of the electrical signal input
to the yarn monitoring control section 60 is greater.
25
However, a configuration in which the voltage is not
inverted may also be adopted. In this case, the correction
of when the voltage of the electrical signal input to the
yarn monitoring control section 60 becomes small (i.e.,
5 when the yarn thickness is increased) corresponds to the
first correction.
In the above-described embodiment, the yarn
monitoring device 6 has a configuration in which the cutter
16 is incorporated. However, the present invention is not
10 limited thereto, and the cutter may be arranged outside the
yarn monitoring device 6, and the cutter may be controlled
by the unit control section 30. In this case, the yarn
monitoring control section 60 outputs the yarn cutting
signal to the unit control section 30, and the unit control
15 section 30 drives the cutter based on the yarn cutting
signal. Furthermore, the yarn monitoring device 6 is
configured to cut the yarn 21 with the cutter 16 and remove
the yarn defect when the yarn defect is detected, but the
yarn monitoring device of the present invention may be a
20 device that merely monitors the state of the yarn 21 without
cutting the yarn 21 with the cutter 16.
In the above-described embodiment, the yarn
monitoring device 6 includes the yarn thickness detecting
section and the yarn travelling length detecting section,
25 but each of the yarn thickness detecting section and the
yarn travelling length detecting section may be realized
with different devices. When the yarn monitoring device
6 does not include the yarn travelling length detecting
section, and the yarn travelling length (travelling speed
30 of the yarn 21) is detected with a device different from
the yarn monitoring device 6, the yarn monitoring device
26
6 may have a configuration including a set of light
projecting section and light receiving section.
The yarn monitoring device 6 is not limited to the
configuration in which a total of two sets of light
5 projecting section and light projecting section are
arranged, where each set is arranged at different positions
on the yarn travelling path. As described above, only one
set of light projecting section and light receiving section
may be arranged. Regardless of whether only one set of
10 light projecting section and light receiving section is
arranged or plural sets are arranged, the number of light
projecting sections and the number of light receiving
sections arranged in one set are not limited to one each.
For example, in one set, one or a plurality of light
15 projecting sections and one or a plurality of light
receiving sections may be arranged. Specifically, a first
set arranged upstream may include one light projecting
section and three light receiving sections, and a second
set arranged downstream may include two light projecting
20 sections and two light receiving sections.
In the above-described embodiment, the predetermined
length for obtaining the yarn reference thickness is
assumed as 25 m, the period of the first correction is
assumed as 5 m, and the period of the second correction is
25 assumed as 35 m, but such values are arbitrary and can be
appropriately changed (e.g., may be double or triple of the
above values). Furthermore, in the above-described
embodiment, the predetermined length for obtaining the yarn
reference thickness and the period of the second correction
30 are assumed to be integral multiple of the period of the
first correction, but may not be integral multiple.
27
The process described in the above-described
flowcharts is one example, and addition, change, change of
order, deletion, and the like of the flow can be made within
a scope not deviating from the present invention.
5 In the above-described embodiment, the period of the
first correction is shorter than the period of the second
correction, but the period of the first correction may be
longer than the period of the second correction depending
on the winding conditions and the like.
10 In the above-described embodiment, the computation
is carried out by introducing values such as the yarn
reference thickness, the yarn average thickness, the
initial adjustment value, the correction adjustment value,
and the correction value, but such computation is one
15 example and can be appropriately changed. For example, the
computation may be carried out assuming the value obtained
by adding the initial adjustment value to the yarn reference
thickness of the above-described embodiment as the “yarn
reference thickness”.
20 Furthermore, in the above-described embodiment, the
correction amount is calculated from the changing amount
when the electrical signal is changed by the temperature
change as illustrated in S111 in the flowchart of FIG. 7.
However, rather than calculating the correction amount from
25 the changing amount, for example, a predetermined fixed
value may be added/subtracted with respect to the previous
correction adjustment value to correct the yarn thickness
when determined that the correction is necessary for every
correction period. Accordingly, the correction can be
30 carried out in a simple manner.
More specifically, a predetermined first fixed value
28
is added every first period to the initial adjustment value
to obtain the correction adjustment value (correction
amount), and the first correction is carried out based on
the obtained correction amount. Furthermore, a
5 predetermined second fixed value is subtracted every second
period from the initial adjustment value to obtain the
correction adjustment value (correction amount), and the
second correction is carried out based on the obtained
correction amount. For example, describing using FIG. 5,
10 at the time point where the yarn travelling length is 5 m
of the first period, the first fixed value is added to the
initial adjustment value to obtain the correction
adjustment value to carry out the first correction. At the
time point where the yarn travelling length is 10 m of the
15 second period, the first fixed value is further added to
the previous correction adjustment value (value obtained
by adding the first fixed value to the initial adjustment
value) to obtain the correction amount to carry out the
first correction.
20 As previously described, the initial adjustment
value is defined when the yarn 21 is not present in the
detection region 70 before the start of the travelling of
the yarn 21. The predetermined fixed value is preferably
set to different values for when the yarn 21 becomes thick
25 and when the yarn 21 becomes thin, but may be set to a same
value. For the predetermined fixed value, a numerical
value that allows apparent change in the yarn thickness and
the actual change in the yarn thickness by temperature drift
to be recognizable in a distinguished manner can be
30 experimentally (by repeating experiments) set in advance.
At least one part of the process carried out by the
29
yarn monitoring control section 60 (e.g., correction
carried out by the correcting section 62) may be carried
out by the unit control section 30 or the machine control
section 11.
5 The configuration of the present invention is not
limited to the automatic winder, and can be applied to other
yarn winding machines such as, for example, a rewinding
machine, a spinning machine (e.g., a pneumatic spinning
machine, an open-end spinning machine), and the like.
10 According to a first aspect of the present invention,
a yarn monitoring device having the following configuration
is provided. Specifically, the yarn monitoring device
includes an optical yarn thickness detecting section and
a correcting section. The yarn thickness detecting
15 section is adapted to detect a yarn thickness of a
travelling yarn. The correcting section carries out a
first confirmation process of confirming the yarn thickness
detected by the yarn thickness detecting section, and
carries out a first correction of correcting the yarn
20 thickness when the yarn thickness confirmed in the first
confirmation process satisfies a predetermined increasing
condition, in a predetermined first period. The
correcting section also carries out a second confirmation
process of confirming the yarn thickness detected by the
25 yarn thickness detecting section, and carries out a second
correction of correcting the yarn thickness when the yarn
thickness confirmed in the second confirmation process
satisfies a predetermined reducing condition, in a
predetermined second period different from the
30 predetermined first period.
Thus, since behavior in the change of the yarn
30
thickness differs between when the yarn thickness is
increased and when the yarn thickness is reduced, the period
corresponding to each case is set so that the yarn thickness
can be corrected at an appropriate timing corresponding to
5 the change in the yarn thickness while taking into
consideration the temperature change during the travelling
of the yarn.
In the yarn monitoring device, the first period is
preferably shorter than the second period.
10 Thus, when the yarn thickness is increased, the yarn
thickness may rapidly change, and hence the period needs
to be set short to frequently carry out the correction. On
the other hand, when the yarn thickness is reduced, the yarn
thickness gradually changes. However, the detection value
15 of the yarn thickness detecting section (i.e., detected
yarn thickness) also gradually changes by the influence of
temperature change. Therefore, when the yarn thickness is
reduced, the period needs to be made long to distinguish
whether the yarn thickness is actually reduced or the yarn
20 thickness seems to be reduced by the influence of
temperature change. When the yarn thickness is increased,
the actual yarn thickness basically changes rapidly, but
the detection value of the yarn thickness detecting section
by the influence of temperature change changes relatively
25 gradually as described above. Therefore, whether the yarn
thickness is actually increased or the yarn thickness seems
to be increased by the influence of temperature change can
be distinguished easily (in a short time). The yarn
thickness thus can be corrected at an appropriate timing
30 corresponding to the change in the yarn thickness.
The above-described yarn monitoring device
31
preferably has the following configuration. Specifically,
the yarn monitoring device includes a yarn travelling
length detecting section adapted to detect a yarn
travelling length that is a length in which the yarn has
5 travelled. The correcting section, based on the yarn
travelling length detected by the yarn travelling length
detecting section, carries out the first confirmation
process and determines whether the yarn thickness confirmed
in the first confirmation process satisfies the
10 predetermined increasing condition every time the yarn
travels a first predetermined length, and carries out the
second confirmation process and determines whether the yarn
thickness confirmed in the second confirmation process
satisfies the predetermined reducing condition every time
15 the yarn travels a second predetermined length.
The timing of correction is thus determined based on
the yarn travelling length, so that the yarn thickness can
be more accurately corrected compared to the case in which
the timing of correction is determined based on time.
20 In the above-described yarn monitoring device, the
correcting section preferably carries out the first
confirmation process and determines whether the yarn
thickness confirmed in the first confirmation process
satisfies the predetermined increasing condition every
25 time a first predetermined time has elapsed, and carries
out the second confirmation process and determines whether
the yarn thickness confirmed in the second confirmation
process satisfies the predetermined reducing condition
every time a second predetermined time has elapsed.
30 The timing of correction thus can be determined
without detecting the yarn travelling length, whereby the
32
process can be simplified.
In the above-described yarn monitoring device, the
correcting section preferably obtains, as a yarn reference
thickness, a value based on an average of yarn thicknesses
5 from start of travelling of the yarn until the yarn travels
a predetermined length or until a predetermined time
elapses, and carries out the first correction based on an
increased amount of the yarn thickness from the yarn
reference thickness, and carries out the second correction
10 based on a reduced amount of the yarn thickness from the
yarn reference thickness.
Thus, the influence of temperature change is assumed
to be small for a predetermined time from the start of the
travelling of the yarn, and hence the influence of
15 temperature change and the like can be accurately estimated
by taking, as a reference, the average (yarn reference
thickness) of the yarn thicknesses acquired during that
time. Therefore, the yarn thickness can be more accurately
corrected.
20 Furthermore, in the above-described yarn monitoring
device, the correcting section preferably carries out the
first correction based on a correction amount obtained by
adding a predetermined first fixed value defined in advance
for every first period to an initial adjustment value
25 defined before the start of the travelling of the yarn, and
carries out the second correction based on a correction
amount obtained by subtracting a predetermined second fixed
value defined in advance for every second period from the
initial adjustment value.
30 In the above-described yarn monitoring device, the
first correction is preferably carried out when a yarn
33
thickness at a terminating time point of a current first
period confirmed in the first confirmation process is
increased by a predetermined amount from a yarn thickness
at a terminating time point of a previous first period, and
5 the second correction is preferably carried out when a yarn
thickness of a current second period confirmed in the second
confirmation process is continuously reduced.
In the above-described yarn monitoring device, the
correcting section preferably calculates an average of yarn
10 thicknesses in a predetermined length or a predetermined
time in past, and carries out the first correction of
correcting the yarn thickness when the average of the yarn
thicknesses at the terminating time point of the current
first period satisfies the predetermined increasing
15 condition.
According to a second aspect of the present invention,
a yarn winding machine having the following configuration
is provided. Specifically, the yarn winding machine
includes a winding section, a yarn thickness detecting
20 section, and a correcting section. The winding section is
adapted to wind a yarn to form a package. The yarn thickness
detecting section is adapted to detect a yarn thickness of
a travelling yarn. The correcting section carries out a
first confirmation process of confirming the yarn thickness
25 detected by the yarn thickness detecting section, and
carries out a first correction of correcting the yarn
thickness when the yarn thickness confirmed in the first
confirmation process satisfies a predetermined increasing
condition, in a predetermined first period, and carries out
30 a second confirmation process of confirming the yarn
thickness detected by the yarn thickness detecting section,
34
and carries out a second correction of correcting the yarn
thickness when the yarn thickness confirmed in the second
confirmation process satisfies a predetermined reducing
condition, in a predetermined second period different from
5 the predetermined first period.
Thus, since the behavior in the change of the yarn
thickness differs between when the yarn thickness is
increased and when the yarn thickness is reduced, the period
corresponding to each case is set so that the yarn thickness
10 can be corrected at an appropriate timing corresponding to
the change in the yarn thickness.
The above-described automatic winder preferably has
the following configuration. Specifically, the automatic
winder includes a yarn travelling length detecting section
15 adapted to detect a yarn travelling length that is a length
in which the yarn has travelled. The winding section winds
the yarn while changing a winding speed at least temporarily.
The correcting section carries out the first confirmation
process and determines whether the yarn thickness confirmed
20 in the first confirmation process satisfies the
predetermined increasing condition every time the yarn
travels a first predetermined length, and carries out the
second confirmation process and determines whether the yarn
thickness confirmed in the second confirmation process
25 satisfies the predetermined reducing condition every time
the yarn travels a second predetermined length.
Accordingly, even with the automatic winder adapted
to wind the yarn while changing the winding speed, the yarn
thickness can be corrected at an appropriate timing by
30 carrying out the correction based on the yarn travelling
length.
35
We Claim:
1. A yarn monitoring device (6) characterized by
comprising:
an optical yarn thickness detecting section (50)
adapted to detect a yarn thickness of a travelling yarn
(21); and
a correcting section (62) adapted to carry out
correction of the yarn thickness,
wherein the correcting section
carries out a first confirmation process of
confirming the yarn thickness detected by the yarn
thickness detecting section, and carries out a first
correction of correcting the yarn thickness when the yarn
thickness confirmed in the first confirmation process
satisfies a predetermined increasing condition, in a
predetermined first period, and
carries out a second confirmation process of
confirming the yarn thickness detected by the yarn
thickness detecting section, and carries out a second
correction of correcting the yarn thickness when the yarn
thickness confirmed in the second confirmation process
satisfies a predetermined reducing condition, in a
predetermined second period different from the
predetermined first period.
2. The yarn monitoring device according to claim 1,
characterized in that the first period is shorter than the
second period.
3. The yarn monitoring device according to claim 1
or 2, characterized by further comprising:
a yarn travelling length detecting section (61)
adapted to detect a yarn travelling length that is a length
in which the yarn has travelled,
wherein the correcting section,
based on the yarn travelling length detected by the
yarn travelling length detecting section,
carries out the first confirmation process and
determines whether the yarn thickness confirmed in the
first confirmation process satisfies the predetermined
increasing condition every time the yarn travels a first
predetermined length, and
carries out the second confirmation process
and determines whether the yarn thickness confirmed in the
second confirmation process satisfies the predetermined
reducing condition every time the yarn travels a second
predetermined length.
4 . The yarn monitoring device according to claim 1
or 2, characterized in that the correcting section
carries out the first confirmation process and
determines whether the yarn thickness confirmed in the
first confirmation process satisfies the predetermined
increasing condition every time a first predetermined time
has elapsed, and
carries out the second confirmation process and
determines whether the yarn thickness confirmed in the
second confirmation process satisfies the predetermined
reducing condition every time a second predetermined time
has elapsed.
5. The yarn monitoring device according to any one
of claims 1 to 4, characterized in that the correcting
section
obtains, as a yarn reference thickness, a value based
on an average of yarn thicknesses from start of travelling
of the yarn until the yarn travels a predetermined length
or until a predetermined time elapses,
carries out the first correction based on an
increased amount of the yarn thickness from the yarn
reference thickness, and
carries out the second correction based on a reduced
amount of the yarn thickness from the yarn reference
thickness.
6. The yarn monitoring device according to any one
of claims 1 to 4, characterized in that the correcting
section
carries out the first correction based on a
correction amount obtained by adding a predetermined first
fixed value defined in advance for every first period to
an initial adjustment value defined before the start of the
travelling of the yarn, and
carries out the second correction based on a
correction amount obtained by subtracting a predetermined
second fixed value defined in advance for every second
period from the initial adjustment value.
7 . The yarn monitoring device according to any one
of claims 1 to 6, characterized in that
the first correction is carried out when a yarn
thickness at a terminating time point of a current first
period confirmed in the first confirmation process is
increased by a predetermined amount from a yarn thickness
at a terminating time point of a previous first period, and
the second correction is carried out when a yarn
thickness of a current second period confirmed in the second
confirmation process is continuously reduced.
8 . The yarn monitoring device according to any one
of claims 1 to 7, characterized in that the correcting
section
calculates an average of yarn thicknesses in a
predetermined length or a predetermined time in past, and
carries out the first correction of correcting the
yarn thickness when the average of the yarn thicknesses at
the terminating time point of the current first period
satisfies the predetermined increasing condition.
9. A yarn winding machine (1) characterized by
comprising:
a winding section (26) adapted to wind a yarn to form
a package;
a yarn thickness detecting section (50) adapted to
detect a yarn thickness of a travelling yarn; and
a correcting section (62) adapted to correct the yarn
thickness,
wherein the correcting section
carries out a first confirmation process of
confirming the yarn thickness detected by the yarn
thickness detecting section, and carries out a first
correction of correcting the yarn thickness when the yarn
thickness confirmed in the first confirmation process
satisfies a predetermined increasing condition, in a
predetermined first period, and
carries out a second confirmation process of
confirming the yarn thickness detected by the yarn
thickness detecting section, and carries out a second
correction of correcting the yarn thickness when the yarn
thickness confirmed in the second confirmation process
satisfies a predetermined reducing condition, in a
predetermined second period different from the
predetermined first period.
10. An automatic winder (1) serving as the yarn
winding machine according to claim 9, the automatic winder
characterized by comprising:
a yarn travelling length detecting section (61)
adapted to detect a yarn travelling length that is a length
in which the yarn has travelled,
wherein the winding section winds the yarn while
changing a winding speed at least temporarily, and
the correcting section,
based on the yarn travelling length detected by the
yarn travelling length detecting section,
carries out the first confirmation process and
determines whether the yarn thickness confirmed in the
first confirmation process satisfies the predetermined
increasing condition every time the yarn travels a first
predetermined length, and
carries out the second confirmation process
and determines whether the yarn thickness confirmed in the
second confirmation process satisfies the predetermined
reducing condition every time the yarn travels a second
predetermined length.