[0001] The present invention relates to a yarn piecing method and a yarn piecing apparatus
used in textile machines such as open-ended spun yarn spinning machines, and fasciated
spun yarn spinning machines and in which a spun yarn spun by and delivered from a
yarn forming means and another yarn withdrawn from a yarn package on which the spun
yarn is wound are pieced to each other.
[0002] Generally speaking, textile machines such as open-ended spun yarn spinning machines
or fasciated spun yarn spinning machines include a drafting means, a yarn forming
means, a yarn taking-up means, a yarn winding means, and the like. When staple fibre
bundles are supplied, a spun yarn such as, a fasciated spun yarn is spun in the yarn
forming means and then wound on a yarn package by the yarn winding means.
[0003] When a yarn breaks in the yarn producing process, a yarn piecing operation is usually
carried out. Namely, the yarn piecing operation includes the steps of stopping a yarn
winding means once, sucking a spun yarn delivered from a yarn forming means (referred
to as a first yarn hereafter) by a first yarn sucking means provided on a yarn piecing
apparatus; withdrawing a yarn from a yarn package (referred to as a second yarn hereafter)
by a second yarn sucking means; and piecing the first and second yarn to each other
by carrying the two yarns to a yarn piecing means.
[0004] In this conventional yarn piecing method, a yarn spun by and delivered from a yarn
forming means during a yarn piecing opeation is sucked and stored in a yarn storing
means provided between a yarn taking up means and the yarn piecing means. Then, when
the yarn piecing operation is completed, the non-rotated yarn package is restarted
to rotate in such a way that the rotational speed thereof is rapidly increased with
a predetermined acceleration to take out the yarn stored in the yarn storing means.
Thereafter, the rotational speed of the yarn package is changed to a predetermined
yarn winding speed to wind up a spun yarn delivered from the yarn forming means.
[0005] In this conventional yarn piecing method, however, since the rotational speed of
the package is increasingly accelerated after the yarn piecing operation is completed,
it is required that the total length of the yarn, i.e. the sum of the length of the
yarn stored in the yarn storing means when the yarn piecing operation is carried out
and the length of the yarn produced during a time from when the yarn package is not
rotated to when the rotational speed of the yarn package reaches a predetermined winding
speed, (usually requiring 0.5 to 1 second), be sucked and stored in the yarn storing
means. Thus, in the conventional method, a yarn storing means having a large yarn
storing capacity is necessary.
[0006] On the other hand, when such a large capacity yarn storing means is provided on a
machine frame, it must be formed in a configuration such that the yarn sucking path
is folded several times as shown in Japanese Unexamined Patent Publication (Kokai)
No. 53-134943, making it difficult to make such a yarn sucking means.
[0007] When a yarn piecing operation is carried out utilizing a knotter, the time required
to piece yarns is very short, for example, 0.1 to 0.3 second, therefore, the yarn
can be sufficiently stored in the yarn storing means without providing a yarn storing
means having a relatively longer length. When a yarn piecing operation is carried
out utilizing a splicer, however, the time required for piecing yarns is usually 0.4
to 0.7 second, longer than the previous method. Accordingly, the amount of yarn stored
in the yarn storing means is increased.
[0008] Therefore, a yarn storing means having an extremely large capacity for storing yarn
is required to be provided when intending to store the yarn produced during the time
in which the rotational speed of the yarn package reaches a predetermined yarn winding
speed from a non-rotated condition and the yarn produced during the yarn piecing operation.
[0009] However, it is very difficult to make a yarn storing means having such a large capacity,
and it is also very difficult to find out a place on a textile machine on which such
a large capacity yarn storing means may be mounted. Thus, it is impossible to use
this kind of yarn storing means in actual production.
[0010] Further, since yarn existing between the yarn piecing means and the yarn package
cannot be wound on the yarn package under a predetermined yarn tension simultaneously
with completion of the yarn piecing operation, a snarling naturally occurs in the
yarn in the yarn piecing means and therefore a problem arises in that snarls are easily
wound onto the yarn package with a normal spun yarn.
[0011] It is an object of the present invention to provide a yarn piecing method and yarn
piecing apparatus in which at least some of the above difficulties are alleviated.
[0012] To attain the objects of the present invention as explained above according to one
aspect of the invention, there is provided a yarn piecing method in which a first
yarn, spun by and delivered from a yarn forming device at a predetermined constant
speed, and a second yarn, withdrawn from a yarn package on which the yarn is wound,
are pieced to each other, the yarn piecing method comprising the steps of withdrawing
the second yarn from the yarn package by a predetermined length, piecing the second
yarn with the first yarn, and starting rotation of the yarn package before a yarn
piecing operation is completed.
[0013] According to another aspect of the present invention, there is provided a yarn piecing
apparatus which comprises a unit travelling along a machine frame provided with at
least a yarn forming means and yarn winding means thereon, the travelling unit being
provided with at least a yarn piecing means, a first-yarn sucking means, a second-yarn
sucking means, a yarn package driving means, and a second-yarn picking-up means, characterized
in that a yarn storing means is further provided on the travelling unit located at
a portion between the yarn piecing means and the yarn winding means provided on the
machine frame.
[0014] Methods and apparatus in accordance with the present invention will now be described,
by way of example only with reference to the accompanying Figures in which:-
Figure 1 is a cross-sectional view of one embodiment of a yarn piecing apparatus of
the present invention used on a spun yarn producing machine;
Figure 2 is an enlarged cross-sectional view of the yarn piecing apparatus shown in
Fig. 1;
Figure 3 is a front plane view of the yarn piecing apparatus taken from a direction
indicated by an arrow Z shown in Fig. 2;
Figure 4 is a schematic view of the yarn gripping means used in the present invention;
and
Figure 5 is a schematic view explaining the sequential yarn piecing operation of the
present invention.
[0015] This embodiment relates to a textile machine with a yarn piecing means thereon. A
drafting means 1 including back rollers 11, middle rollers 12 and front rollers 13
is provided on a machine frame 10.
[0016] Note that in the drafting means 1, the back rollers 11 are provided with a stopping
mechanism for stopping rotation by separating the rollers from a driving shaft (not
shown).
[0017] A yarn forming means 2 is also provided in the machine frame 10 adjacent to the front
rollers 13 of the drafting means 1. A staple fibre bundle delivered from the front
rollers 13 is sucked into it and formed into a fasciated spun yarn, for example, by
applying a whirling force generated by compressed air onto the staple fibre bundle.
[0018] A yarn forming means as shown in Japanese Unexamined Patent Publication No. 63-243335
can be used in the present invention.
[0019] A yarn taking-up means 3 is also provided. It is arranged underneath the yarn forming
means 2 with a predetermined space therebetween.
[0020] The yarn taking-up means 3 includes a driving roller 31 and a nip roller 32 having
a small width. One end of the rotating shaft thereof is supported by a suitable bearing.
The means 3 can take up a spun yarn delivered from the yarn forming means 2 at a predetermined
speed.
[0021] A yarn storing means 4 is provided and arranged underneath and adjacent to the yarn
taking-up means 3.
[0022] The yarn storing means 4 includes a yarn sucking tube 41 having a substantially flat
rectangular cross-sectional configuration. One end is opened to a position through
which the spun yarn passes while the opposite end is connected to a pneumatic duct
42 with a negative pressure source (not shown).
[0023] A tensioning means 5 for applying a suitable tension to a spun yarn is provided underneath
the yarn storing means 4 and includes a yarn tenser 51, a cutter, a slab catcher,
or the like.
[0024] A yarn winding means 6 is provided underneath the yarn tensioning means 5 and includes
a driving roller 61 connected to a line shaft through a clutch mechanism and provided
with a groove on a peripheral surface thereof for traversing a yarn to be wound on
a package and a cradle, rotatably supporting a yarn bobbin and having a pressuring
means whereby the yarn bobbin is attached to a surface of the driving roller 61 with
a predetermined surface pressure to wind the spun yarn delivered from the yarn taking-up
means 3 on the yarn bobbin.
[0025] Usually, a yarn producing unit includes a drafting means 1, a yarn forming means
2, a yarn taking-up means 3, a yarn storing means 4, a yarn tensioning means 5, and
a yarn winding means 6, and a plurality of the yarn producing units are arranged in
a longitudinal direction of a textile machine frame 10 with a predetermined space
therebetween.
[0026] On the other hand, a yarn piecing apparatus 7, i.e., a traveling unit, is provided
in the machine frame 10 and travels along rails 10a and 10b arranged in a longitudinal
direction of the machine frame 10 to piece yarns on a yarn producing unit in which
yarn breakage occurs.
[0027] Note that when yarn breakage occurs, a first yarn delivered from the yarn forming
means 2 and a second yarn withdrawn from a yarn package 80 on which a spun yarn is
wound are pieced to each other.
[0028] A detailed description of the yarn piecing apparatus will be explained hereunder
with reference to Figs. 2 and 3.
[0029] In Fig. 2, a splicer 71 is provided on the traveling unit 70 and arranged between
the tensioning means 5 and yarn winding means 6 as explained above to piece a first
yarn delivered from the yarn forming means 2 and a second yarn withdrawn from a yarn
package on which a spun yarn is wound.
[0030] The splicer 71 is fixedly mounted on a traveling unit 70 by a bracket 93 and includes
a yarn guiding plate for guiding a yarn to a predetermined place at which the yarn
piecing operation will be carried out, yarn gripping needles for gripping the first
and the second yarn, and a yarn piecing means.
[0031] A first-yarn sucking means 72 is provided pivotally mounted on the traveling unit
70, it swings around a rotating rod 90 having a hollow tube 96 therein, one end thereof
being connected to a negative pressure source (not shown), for example, a blower.
[0032] The another end of the hollow tube 96 is connected to an opening portion 95 of the
first yarn sucking means 72 to form a yarn sucking aperture.
[0033] The sucking aperture can move between a yarn sucking portion (A) beneath the yarn
taking-up means 3 and a waiting portion (B) beneath the yarn splicer 71 so the yarn
delivered from the yarn taking-up means 3 is sucked into the sucking means 72 as a
first yarn and thus the first yarn is carried to a yarn piecing portion of the splicer
71.
[0034] A second-yarn sucking means 73 is provided pivotally mounted on the unit 70. It swings
around a rotating rod 92 having a hollow tube 97 therein, one end thereof being connected
to a negative pressure source (not shown), for example, a blower.
[0035] The other end thereof is formed as a yarn sucking aperture 98 having the same width
as that of the yarn package and is connected to a negative pressure source as mentioned
above through the hollow tube 97.
[0036] The sucking aperture 98 thereof can move between a yarn sucking portion (C) adjacent
to a yarn package 80 provided on a cradle 62 and a waiting portion (D) beneath the
yarn splicer 71.
[0037] In the present invention, a roller driving means 74 is provided and includes an arm
74a pivotally mounted on the unit 70, utilizing a bearing means, a roller 74b rotatably
mounted on one end of the arm 74a, a cylinder for rotating the arm 74a (not shown),
and an electric motor such as an induction motor, or a pulse motor (not shown) for
rotating the roller both forward and reverse.
[0038] Therefore, the driving roller 61 of the yarn winding means 6 can be rotated both
forward and reverse.
[0039] A yarn storing means 75 is provided on the traveling unit arranged between the yarn
winding means 6 and the yarn splicer 71 and includes a yarn sucking tube 75a, one
end thereof being close to a yarn passage, being cut and opened to form a yarn sucking
aperture, while the longitudinal direction thereof being perpendicular to a yarn
traveling direction which is vertical, and another end of the yarn sucking tube 75a
is connected to a negative pressured source (not shown), for example, a blower.
[0040] A yarn gripping means 76 is also provided on the unit 70 and arranged adjacent to
an upper portion of the yarn storing means 75.
[0041] As shown in Fig. 4, the yarn gripping means 76 includes a supporting means 76a, a
solid portion 76b for gripping yarns fixedly mounted on the supporting means 76a,
a movable portion 76c for gripping yarn and slidably mounted on the solid portion
76b and solid by an electric actuator (not shown), and a detector 76d for detecting
a yarn. When a yarn withdrawn from the yarn package 80 is detected, the yarn is gripped
by the yarn gripping means 76.
[0042] Accordingly, when the package 80 is rotated in the reverse direction, the yarn is
sucked by and stored in the sucking tube 75 of the yarn storing means 73.
[0043] A yarn picking-up means 77 is further provided pivotally mounted on the unit 70 through
a rotatable rod 91. It can move between a yarn pulling up position (E) above the yarn
splicer 71 and a waiting position (F) beneath the yarn sucking means 75 in accordance
with a rotation of the rod 91, whereby a yarn between the yarn gripping means 76 and
the second yarn sucking means 72 can be picked up and carried to a yarn piecing portion
of the splicer 71.
[0044] The yarn is withdrawn from the package by rotating it in an opposite direction to
the normal yarn winding direction with the roller driving means 74. The yarn length
(L) stored in the yarn storing means 75 at that time must be the sum of the yarn length
(l₁) wound on the yarn package during a time in which the rotation of the yarn package
reaches a predetermined speed from the non-rotated condition and a yarn length (l₂)
corresponding to an error.
[0045] The yarn length (l₂) should be determined taking into account the accuracy of the
electric motor of the roller driving means 74 or inverter for controlling the rotation
of the motor and the variation of the yarn length withdrawn from the package depending
upon a diameter of the yarn package 80, yarn traversing position, yarn traversing
width, or the like.
[0046] Therefore, when a pulse motor is used as a roller driving means, the length (l₂)
can be reduced and can be set at the range of 10 to 50 cm.
[0047] The acceleration when the rotational speed of the yarn package is increased from
the non-rotated condition to a predetermined yarn winding speed is preferably set
at the maximum extent at which slippage does not occur between the roller 74b supported
by a swing arm 74a of the roller driving means 74 and the driving roller 61 of the
yarn winding means 6 or between the driving roller 61 and the yarn package 80.
[0048] The swing arm 74a is pivotably mounted on a rotatable rod 94 whereby the arm 74a
can be swung in accordance with rotation of the rod 94.
[0049] In the present invention, a yarn piecing operation can be carried out with the same
timing regardless of the yarn package size being small or large, by keeping the yarn
length stored in the yarn storing means 75 constant and setting a driving force for
driving the roller driving means 74 and a time for increasing the rotational speed
of the package from a non-rotated condition to a predetermined rotational speed so
as to keep the acceleration of the package constant regardless of the package size.
[0050] Measurement of yarn length stored in the yarn storing means can be carried out by
counting the rotation of the roller driving means 74 or by a yarn detector provided
at a predetermined position in the yarn storing means 75.
[0051] On the other hand, the timing for energizing the splicer may be varied depending
upon the difference of acceleration of the yarn package keeping the yarn length stored
in the yarn storing means constant.
[0052] The drafting means 1, the yarn winding means 6, and the yarn piecing means 7, are
controlled by a controlling means comprising an input circuit for setting operations,
a memory circuit, a comparator, a processing circuit, a operation directing circuit,
or the like (not shown), or a microcomputer.
[0053] When yarn breakage occurs during a yarn forming operation and yarn winding operation
in the spun yarn spinning machine as explained above, first the rotation of the back
rollers 11 in the drafting means 1 is stopped in response to a signal generated from
a controller (not shown), whereby delivery of a spun yarn from the yarn forming means
2 is interrupted. Rotation of the yarn package 80 is stopped due to the driving roller
61 being removed from a line shaft by actuating a clutch (not shown).
[0054] Then, when the yarn piecing apparatus 7 is moved to the yarn producing unit on which
the yarn breakage occurred, the yarn piecing operation is carried out along sequential
steps shown in Fig. 5 in turn.
[0055] First, when the first yarn sucking means 72 is rotated and the sucking aperture thereof
is moved to the position (A) beneath the yarn taking-up means 3, the drafting means
1 is restarted to supply a staple fiber bundle to the yarn forming means 2, whereby
a fasciated spun yarn or open-ended spun yarn is spun out therefrom and delivered
from the yarn taking-up means 3 at a predetermined speed.
[0056] Next, the yarn delivered from a point formed between the driving roller 31 and the
nip roller 32 is sucked by the yarn sucking aperture as a first yarn.
[0057] Simultaneously with the operational movement as mentioned above, the second yarn
sucking means 73 is rotated and the aperture thereof is moved to a position (C) for
sucking the second yarn above the yarn package 80 while the roller driving means 74
is actuated, whereby the arm 74a is rotated enabling the roller 74b to be contacted
to the drive roller 61 of the yarn winding means 6.
[0058] Therefore, the yarn package 80 is rotated in an opposite direction to the yarn winding
direction with the driving roller 61.
[0059] After that, an end of the yarn contacting a peripheral surface of the yarn package
is sucked into the yarn sucking aperture (shown in Fig. 5-1).
[0060] When the yarn is withdrawn from the yarn package 80 as a second yarn, the second
yarn sucking means 73 is rotated to move back the yarn sucking aperture to a waiting
position (D) (shown in Fig. 5-2).
[0061] After this, when the yarn is detected by the yarn detector 76d of the yarn gripping
means 76, an electromagnetic actuator (not shown) is actuated to withdraw the movable
portion 76c, whereby the yarn is fixedly gripped between the movable portion 76c and
the solid portion 76b.
[0062] During these operations, the yarn package is continuously rotated, whereby a certain
amount of the yarn is withdrawn from the yarn package 80.
[0063] Accordingly, the yarn withdrawn from the yarn package 80 is sucked into the yarn
sucking tube 75a of the yarn storing means 75 through an aperture thereof and stored
in the yarn storing means in a U-like form (shown in Fig. 5-3).
[0064] During the operation as shown in Fig. 5-3, the first-yarn sucking means 72 is rotated
to move back the sucking aperture to the waiting position (B), thereby the yarn is
carried to a yarn piecing portion of the splicer 71.
[0065] On the other hand, when a predetermined yarn length (L) is sucked into the yarn sucking
tube 75a due to the reverse rotation of the yarn package 80, the roller driving means
74 is actuated to stop the rotation of the roller 74b (shown in Fig. 5-4).
[0066] The yarn carried to the yarn piecing portion of the splicer 71 in the operation as
above is fixedly gripped by a gripping needle (not shown).
[0067] Therefore, the yarn delivered from the yarn taking-up means 3 is sucked into the
yarn storing means 4 in a U-shaped form.
[0068] After that, the yarn between the yarn gripping means 76 and the second-yarn sucking
means 72 is picked up by the rotating yarn picking-up means 77 to carry the yarn to
the position (E) locating above the splicer 71, whereby a part of the yarn can be
carried to the yarn piecing means, i.e., a splicer 71.
[0069] When the yarn picking-up means 77 is rotated, the roller driving means 74 is actuated
simultaneously with or before the rotation of the yarn picking-up means, so the yarn
package can be rotated in a yarn winding direction by the driving roller 61 of the
yarn winding means 6 due to the rotation of the roller 74b.
[0070] At this time, the yarn package 80 is rotated with a predetermined acceleration when
the package is started to rotate from the non-rotated condition and to the condition
at which the package is rotated at a predetermined speed. (This acceleration means
the maximum acceleration not causing any slippage between the roller 76b and the driving
roller 61 or between the driving roller 61 and the yarn package 80.) The yarn stored
in the yarn storing means 75 is withdrawn therefrom gradually and wound on the yarn
package again.
[0071] Then, when the splicer is actuated, the first yarn delivered from the yarn taking-up
means 3 and the second yarn withdrawn from the yarn package 80 are pieced to each
other (shown in Fig. 5-5).
[0072] When the yarn piecing operation by the yarn splicer 71 is completed, the yarn gripping
means 76 is simultaneously actuated to project the movable portion 76c, whereby the
yarn gripped by the yarn gripping means is released.
[0073] Up to this time, the yarn previously stored in the yarn storing means 75 is mostly
wound up on the yarn package 80 and no yarn remains therein.
[0074] While, in the present invention, no snarling will occur in the yarn piecing means
because a suitable yarn tension is stably applied to the yarn between the splicer
71 and the yarn package 80 by the yarn storing means 75 (shown in Fig. 5-6).
[0075] When all the yarn stored in the yarn storing means 75 is wound on the package, a
yarn winding operation of the yarn stoed in the yarn storing tube 4 is started.
[0076] At this time, the rotating speed of the yarn package 80 already reaches a predetermined
yarn winding speed (shown in Fig. 5-7).
[0077] When the yarn piecing operation as explained above is completed, the roller driving
means 74 is actuated to rotate the arm 74a and to remove the roller 74b from the package
80, while the clutch of the yarn winding means 6 is actuated to couple the driving
roller 61 with the line shaft, whereby the normal yarn winding operation is carried
out.
[0078] Thus, since the yarn of the yarn package can be wound with a predetermined winding
tension simultaneously with the completion of the yarn piecing operation, no snarling
occurs in the yarn in the yarn piecing means.
[0079] Generally speaking, since the yarn winding speed of the yarn winding means 6 is faster
by 2 to 3% than the yarn delivering speed of the yarn taking-up means 3, the yarn
stored in the yarn storing means 4 during the yarn piecing operation, can be wound
on the yarn package 80 (shown in Fig. 5-8).
[0080] According to the yarn piecing method of the present invention, in the case of a yarn
spun out from a yarn forming means at a constant speed and pieced with a yarn withdrawn
from a yarn package on which a yarn was wound, first a yarn piecing operation is carried
out by withdrawing a predetermined amount of yarn from the yarn package and the package
is rotated with a certain acceleration before the yarn piecing operation is completed.
[0081] Therefore, the yarn can be wound on the yarn package simultaneously with the completion
of the yarn piecing operation, enabling shortening of the length of the yarn storing
means mounted on the machine frame and facilitating production of the same.
[0082] On the other hand, since the rotational speed of the yarn package reaches a desired
yarn winding speed at the time when the yarn piecing operation is completed, yarn
piecing operation utilizing a splicer can be carried out during the time in which
the rotational speed of the yarn package is increased from the non-rotated condition
to the predetermined rotational speed and thus a yarn piecing operation with a splicer
is possible by reforming a conventional textile machine provided with a knotter as
a yarn piecing means.
[0083] Further, in accordance with the yarn piecing method of the present invention, occurrence
of snarling can be effectively prevented on a yarn in the yarn piecing means because
a suitable yarn tension is applied to the yarn between the yarn piecing means and
the yarn package by the yarn storing means and the yarn can be wound on the package
at predetermined yarn winding tension simultaneously with the completion of the yarn
piecing operation.
[0084] In the yarn piecing method as explained above, the yarn piecing operation can be
stably carried out by effecting the following:
storing a yarn withdrawn from a yarn package in a yarn storing means provided between
a yarn piecing means and the yarn package;
winding again the yarn withdrawn from the yarn package on the yarn package on or just
after the completion of the yarn piecing operation:
making the amount of yarn withdrawn from the yarn package and stored in the yarn storing
means constant regardless of a winding diameter of the yarn package; and
making an acceleration ratio to rotate the yarn package approximately constant regardless
of a winding diameter of the yarn package.
[0085] The yarn piecing method as mentioned above can be carried out by utilizing a yarn
piecing apparatus mounted on a traveling unit moving along a machine frame and including
a yarn piecing means, a first-yarn sucking means, a second-yarn sucking means, a roller
driving means, and a yarn picking-up means. The yarn piecing apparatus may be further
provided with a yarn storing means used for the yarn piecing operation on the traveling
unit arranged between the yarn piecing means and the yarn winding means provided on
the textile machine frame.
[Example]
[0086] First embodiment of the present invention will be explained hereunder.
[0087] A roller driving means 74 driven by a motor is provided in a yarn piecing apparatus
and an arm 74a is pressed by a fluid cylinder with a predetermined pressure causing
a roller 74b of the roller driving means 74 to be pressed against a driving roller
61.
[0088] The driving roller 61 has a clutch inside thereof and thereby the driving roller
61 can rotate freely due to the driving roller being separated from a driving shaft
when a yarn piecing operation is carried out.
[0089] On the other hand, when the driving roller is accelerated, a cradle 62 is swang by
the fluid cylinder to press a package 80 against the driving rolle 61 with a pressure
of 6 kg which is higher than that in a normal yarn winding operation to rotate the
roller 74 and thus the package 80 is rotated by the driving roller 61.
[0090] In this embodiment, a friction coefficiency between the package 80 and the driven
roller 61 is about 0.18 and accordingly, a driving force (T) on a surface of the package
80 which is transferred from the driving roller 61 to the package 80 will be 1.08
kg (6 kg x 0.18 = 1.08 kg).
[0091] While, an inertial force GD² of a bobbin, a package and a driving roller respectively
will be given as follows;
Item |
Diameter |
DG² |
Bobbin |
60 mm |
0.00015 kgm² |
Package |
150 mm |
0.011808 kgm² |
Package |
280 mm |
0.146831 kgm² |
Package |
300 mm |
0.193595 kgm² |
Driving roller |
82 mm |
0.0048 kgm² |
[0092] And when a winding seed is 185 m/min. a rotation number of the bobbin, the package
and the driving roller respectively will be given as follows;
Item |
Diameter |
R.P.M. |
Bobbin |
60 mm |
981 R.P.M. |
Package |
150 mm |
392 R.P.M. |
Package |
280 mm |
210 R.P.M. |
Package |
300 mm |
196 R.P.M. |
Driving roller |
82 mm |
718 R.P.M. |
an accelerated time for the package 80 (a rising up time for the yarn winding speed)
having a maximum torque without occurring a slip between the package 80 and the driving
roller 61, can be calculated utilizing the data as follows;
Item |
Diameter |
Accelerated time |
Bobbin |
60 mm |
0.01 sec |
Package |
150 mm |
0.15 sec |
Package |
280 mm |
0.54 sec |
Package |
82 mm |
0.62 sec |
[0093] Note, that the accelerated time (a rising up time for the yarn winding speed) will
become maximum when the diameter of the package is 300 mm in which the rotational
number is minimum while the GD² is maximum.
[0094] Accordingly, regarding the accelerated time of the package (a rising up time for
the yarn winding speed), when the package is accelerated linealy from 0 m/min to 185
m/min with more than 0.62 seconds, the slippage between the package 80 and the driving
roller 61 will be prevented and thereby the yarn winding speed on the package can
be risen with the same accelerating speed from one package condition the diameter
thereof being 60 mm to another package condition the diameter thereof being 300 mm.
[0095] In the yarn piecing apparatus of this embodiment, when a driving motor requires a
voltage source having a frequency of 60 Hz at a time when the driving roller 61 rotates
at a rotational seed of 185 m/min, the yarn winding speed is risen linearly within
0.62 seconds by changing the frequency of the driving motor from 0 Hz to 60 Hz utilizing
an inverter.
[0096] In a practical operation in the apparatus above, the actual accelerated time of the
package (a rising up time for the yarn winding speed) may be set at around 0.7 second
taken errors into the account not to reduce the actual accelerated time of the package
below 0.62 seconds.
[0097] Second embodiment of the present invention may be considered as follows;
[0098] When the yarn storing means has a lots of capacities, a feed back control is not
required, although in order to improve its accuracy, a feed back control may be adopted
in which a frequency of an inverter is changed with response to a detected signal
with respect to a rotation number of an output axis of a motor.
[0099] Alternatively, another method may be used in which a DC motor is utilized and the
voltage to be supplied thereto may be changed in accordance with a detected rotational
speed of the motor or in which a pulse motor, a survo-motor or the like is used.
[0100] The third embodiment of the present invention may be considered as follows;
[0101] In the previous embodiment, a method in which the yarn winding speed will be risen
with a constant accelerated speed, is disclosed, although another method may also
be used in which a torque of the driving motor for the driving roller 61 is set at
a constant level and utilizing an amount of a yarn withdrawn from the yarn storing
means corresponding to an amount of a yarn stored in the yarn storing means, calculated
from the accelerated time as mentioned above, as a reference, a large amount of yarn
is stored in the yarn storing means when the diameter of the package is small, while
a small amount of yarn is stored therein when the diameter of the package is large.
[0102] In this method above, however, a means for detecting a diameter of the package is
necessary and further since the accelerated time of the package (a rising up time
for the yarn winding speed) is relatively high when the diameter of the package is
small, when the condition of the accelerated time thereof is set at the same condition
as that of the package having a large diameter, the amount of the yarn stored in the
yarn storing means should be increased and thus the total length of the yarn storing
means 75 should be enlarged with respect to that used in a method in which a constant
accelerated speed is used.
[0103] The fourth embodiment of the present invention also may be considered as follows;
[0104] Further, there is another method in which the accelerated speed can be calculated
by measuring a yarn length (yarn length stored in the yarn storing means) which is
withdrawing from the yarn storing means 75.
[0105] This method, however, will be resulted in the same method as that in which a constant
accelerated speed is utilized if the package is accelerated under a condition such
as no slippage will occur between the package 80 and the driving roller 61.