Note: Descriptions are shown in the official language in which they were submitted.
3~
Background of the Invention
This invention relates to improvements in a process for
the automatic exchange of bobbins during windlng of a yarn,
preferabl~ a yarn of Spandex, and it relates fur-ther to an apparatus
adapted for carrying out said process. Such an apparatus is known
as an auto-doffer among those skilled in the art.
Although the invention is not limited to the exclusive
use o~ elastic yarns, of which Spandex is preferably the following
description will be made with the use of elastic yarns because the
invention can be most favorably adapted in the manufacture of such
treatment-sensitive kinds of yarns.
In the exchange operatlon of fully wound bobbins on yarn
winding machines which are used in the wet-, melt- and dry spinning
processes of elastic yarns, a conventional technique has developed.
This techni~ue individually removes a fully wound bobbin,
preferably consistina of a paper tube, and positions a new bobbin
on the holder. But the initiation o~ the conventional winding
occurs only a-Eter cutting the continuously supplied yarn and
introducing the end of the yarn into a suction gun on winding the
end a.round a roll.
The result is the accumulation of a large amount of
waste ~arn. Therefore, yarn production and packaging costs rise.
In the case of the elastic yarns as compared with o~her
kinds of yarns, the winding yarn quantity must be considerably
reduced mainly for technical reasonsl and therefore, the bobbin
exchange frequency must be increased despite obvious uneconomical
and lnefficien-t operational results.
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Even if the bobbin exchange jobs are carried out
exclusi~ely or subs~an-tial~y manually, unwieldy operation is
invited by virtue of the difficulty in handling elastic yarns.
For these reasons, the bobhin exchange job, including
manual operations for exchanying bobbins are highly ~roublesome
and inefEicient.
Various and numerous improvements have been proposed
and executed in the auto-doffering of bobbins if the yarns are
other than elastic yarns. However, in the case of polyurethane
elastic yarns, the auto-doffer appliances could not be used per se,
on account of the rubber-like elastic nature of such modern yarns.
Even if conventional yarn cutters are used in the yarn-
cut jobs during the bobbin exchange, reliable cutting could not be
achieved, because these elastic yarns are highly extendable and
! elastic. Threading and unthreading o these elastic yarns through
individual traversing members were also very highly troublesome
because of the elastic extension of these yarns.
Specifically designed various means for an automatic
yarn cutter and/or auxiliary means for assisting in the yarn catch
by the bobbin must be provided for the automatic bobbin exchange
machineries to provide a solution to the lony-felt problems of the
prior art.
Summary of the Invention
It is therefore an object of the present invention to
provide an efficient and improved techni~ue for the achievement
of an automatic bobbin exchange technique, without producin~ a
significant amount of waste yarn, even if elastic ~arns are used.
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Other objects, features and advantages of the present
invention will become more apparent when the following detailed
description of the invention is read in consultation with the
accompanying drawings which substantially illustrate an embodlment
of the invention.
Brief Description of the Drawings
-
In the drawings:
Fig. 1 is a side elevation of essential parts of an
inventive bobbin exchanger.
Fig. 2 is an enlarged perspective view of a friction
drive roll, a drive and an operation control of t~e latter and a
bobbin under cooperation with said drive roll, as main constituents
of said exchanger machine.
Fig, 3 is a plan view of the machine shown in Fig. 1.
Fig. 4 is a sectional front view of an intermediate
coupling ring member through which, drive is transmitted from the
friction drive roll to head portion thereo~.
Fig. 5 is a sectional plan view of essential parts
shown in Figv 1.
Fig. 6 is a substantially sectional view of an embodiment
of an eccentric doughnut ring and an operating arm thereo made
integral therewith.
Fig. 7 is a front view thereof.
Fig. 8 is a side view of a pneumatic piston-and-cylinder
unit adapted for operational control of the eccentric doughnut
ring shown specifically in Figs. 6 and 7.
Fig. 9 is a front view of a ratchet plate attached to a
bobbin holder employed.
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Fig. 10 is a timing schedule chart oE four difEerent
pneumatic piston-cylinder units employed in the machine.
Fig. 11 is an enlarged view of a part of Fig. 5.
Figs. 12 and 13 are two schematic explanatory views
of the cooperation of friction drive roll r doughnut ring and
bobbin.
Detailed Description of the Invention
Referring no~ to the accompanying drawings, a preferred
embodiment of the invention will be described in detail.
In Fig. 1, numeral 1 represents a radial arm type,
bobbin holder, having a plurality, (four in the present embodiment~,
of arms la, lb, lc and ld, the root ends of the latter being made
integral with a center boss 6. These radial arms mount respective
bobhins 2, 3, 4 and 5 at their ou-ter ends in an easily detachable
- manner, as will be later more fully described.
The bobbin 2 is shown in Fig. 1 in its engaging position
with a friction drive roll 51 which is shown only schematically
and in its position on account of its conventionally known design.
Each of the radial arms la, 1~, lc and ld represents a channel
configuration when seen in its front or sectional configuration
as shown in Fig. 5.
As most clearly seen from Fig. 5, the boss 6 is practically
a sleeve which is rigidly coupled by means of a key 7 with a shaft
8 which is rotatably moun-ted in a pair of separated front and rear
' antifriction bearing units 9 and 10.
Non-rotatable part 9a of the front bearing unit 9 is
slidably supported through a bearing sleeve 1~ on a horizontally
extending rod member 11 of a framework 15. Non-rota-table part lOa
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of the rear bearing unit 10 is slidably mounted throuyh mounting
sleeves 18 and 19 on a pair of mutually parallel rod members 13
and 1~ o~ sald framework 15, these members 13 and 14 being also
parallel to the foregoing rod member 11. The plurality of parallel
rod members acts to slidably support the bearing means. If
necessary, however, these two rod members 13 and 1~ may be replaced
by a single rod. In ~ig. 5, the oppositely arran~ed bobbins 2 and
are shown on the radial arms la and lc which are positioned
vertically in Fig. 1.
During the bobbin exchange operation, a certain idle
gap must be kept between the friction drive roll and a new empty
bobbin, so as to avoid otherwise possible yarn catch by the
drive roll. Such a procedure is rather` conventional. It should
be noted, however, the basic properties of the yarn part (as
- wound on the new bobbin after initiation of the winding action
thereon and until the yarn part will have filled the said idle
gap so that the bobbin will carry out its yarn winding operation at
; its normal operational speed by direct contact with the drive roll)
are dif~erent from those of the further yarn part which will be
wound further on the bobbin; and therefore, the initial yarn part
must be removed from a completely wound-up bobbin, so as to ensure
an equal quality o~ the whole yarn mass regardless of specific
outer or inner yarn layers. This yarn part's removal from the
completely wound-up yarn package or bobbin has caused much trouble
in the yarn packaying operation. One of the main features of the
present invention resides in the novel technique in which the
necessary idle gap is formed between a new bobbin and the
drive roll during the yarn e~chanye period. ~Ihile the yarn windiny
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speed i5 substantially accelerated subseauent to the completion
of the yarn exchange operation, the said idle gap is caused to
disappear and at the same time the bobbin is caused to recover its
normal yarn winding speed.
Referring now to Fig. 2, the mechanism employed ~or the
above~purpose will be described in detail.
The friction drive roll is shown again at 51 r yet in a
more specific way. This roll 51 is continuously ~riven at a certain
constant rotational speed. The new bobbin is shown at 2 as before.
Numeral 100 represents only schematically the yarn which is fed
from a conventional yarn suppl~ source, not shown. ~ double headed
arrow 101 indicates the reciprocations of a conventional traverse
guide 103 which is shown only schematically. This yuide is
positioned in proximity to said drive roll 51 which has an enlarged
head or shoulder 52.
In Fig. 3, numeral 53 represents an eccentric dou~hnut
ring, made o~, preerably, rubber or soft synthetic resin material,
aaa~ted for cooperation with the enlarged head portion 52 of the
drive roll. A unique cooperation mode between these two members
52 and 53, to be described, provides an important feature of the
invention.
Referring to Fig. 2, when the drive roll head 52 is brought
into contact with a rubber end portion 58 of bobbin 2, an engaging
relationship between drive roll 51 and the bohbin 2 will be
established, which drives the bobbin at its surface speed at at
least 50% of the speed of the drive roll 51 by virtue of a
substantial difference between the respective diameters. The
rotational center of the enlarged head 52 and ihat of the drive
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roll proper 51 is ~ept sligh-tly eccentric, as will be described
later more in detail.
Numeral 7~ represen-tsa provisionally fixed and manually
rotatable sleeve and the said doughnut ring 53 is mounted on the
cylindrical outer surface of said sleeve 74, the head portion 52
being in practice and more specifically a separate me~ber which is
mounted through antifrictional bearing means 27 on the cylindrical
surfac~ of the ring 53 (refer to also Flg. 5).
A line shaft 55 is rotatably mounted by bearing means
to be described within the sleeve 74, so as to transmit driving
tor~ue to the friction drive roll 51.
Numeral 102 denotes a driver for driving the line shaft
55 and comprises a pair of mutually meshing mating gears S6a and
56b. The latter gear 56b is ~echanically connected to a prime
mover, preferably an electric motor, not shown, and is driven
therefrom.
Bobbin end portion 58, made preferably of rubber or
the like resilient material, as was already referred to herein-
before, constitutes a reduced cylinder and is adapted for
cooperation with the outer periphery of the drive roll head 52,
as was referred to.
Numeral 59 represents, schematically a double-acting
fluid piston-cylinder assembl~ to be operated by introduction of
compressed air although inlet and outlet openings and conduits
therefor have been o~itted from the drawin~ for simplicity of the
drawing. The piston, no-t shown, of the assembly 59 is mechanically
connected with a piston rod 59a which is lin~ed at its forward
end with the tip end oE an operating arm 60, the root end of the
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latter being made integral with the said riny 53. As shown in
Fig. 2, the operating angular range of said operating arm 60
is represented by 0 which ma~ preferably be 9~ deyrees. When the
piston occupies its retrac-ted position within the cylinder, the
arm is kept at its full line position. With the piston occupying
its advanced position, the arm will be at its chain-dotted line
position 60'.
The torque transmission to the head portion 52 is made
through friction drive roll 51. However, since the head portion
52 throuyh antifriction bearing means 80 and the rotational axes
of roll 51 and head portion 52 are offset from each other by a
certain small definite distance l'e", the necessary coupling means
provided between them must have a special design, as will be
described below.
! - More specifically, head por-tion 52 has a number of
parallel and concentric longitudinaI coupling pins 64 as most
clearly seen from Figs. 4 and 5. In Fig. 5, however, these
coupling pins 64 are represented b~ only one pin. These pins
are kept in engagement by a corresponding number of reception
recesses 63a which are formed in the outer peripheral surface
o a COUpling ring 63 made of a resilient plastic, thus the
both members 52 and 63 are rotatable in synchronization with each
other.
Second series of reception recesses 63b are formed
periodically in the inner peripheral surface of the same ring 63
for reception of a second series of concentrically arranged,
longitudinally extending coupling pins 62 which are fixed to the
friction drive roll 51. Therefore, it will be seen that the both
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members 51 and 63 are adapted for rotation in synchronization with
each other.
The rotational center of the first coupling pins 62 is
shown at 62' in Figs. 3 and 4, while that of the second coupling
pins 64 is shown at 64', the offse-t dis-tance being "e" as shown.
The driver 102 includes more specifically a drive shaft
70 which is attached rigidly to the gear 56b by a key 70a, as shown
in Fig. 5.
The drive shaft 70 is rotatably mounted in a pair of
antifriction bearings 71a; 71b which are separated a certain
definite distance from each other by means of a separator sleeve
72, said bearing being positioned within a socket like projection
104a of machine frame 104. The outer end of the drive shaft 70 is
connected with a prime mover, as was indicated only brie~ly here-
inbefore. A laxge and outer sleeve 73 and a smaller and inner
sleeve 74 are coupled rigidly to each other by press fit or other
conventional fixing technique and rigidly mounted in the said
machine frame 104, althouah the mounting means have been omitted
for simplicity. The line shaft 55 is rotatably mounted more
specifically by means of a pair of bearings 75a and 75b which are
positioned in the smaller and larqer sleeves 74 and 73, respectively.
Friction drive roll 51 is fixedly attached to the line
shaft 55, more specifically by means of a key 76 shown in Fig. 5,
for synchronized rotation. The operation arm 60 is shown in Figs.
2, 3 and 5, and a modified shape of the arm is shown at 60" in
Figs. 6 - 7. In Fiy. 8, the arm is shown as having been modified,
but denoted with former reference characters 60 and 60'.
Nex-t, referring to Figs. 12 and 13, the workiny
cooperation be-tween the drive roll 51 and the bobbin 2 will he
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described. Fig. 12 illustrates -the normal working condition
while Fig. 13 illus-trates the operating condition when a new
empty bobbin has been.brought to position.. In these Figures,
however, the working angle of operating arm 60 or 60" of the
doughnut ring 53, not shown in these Figures, is assumed to be
180 for clearer illustration of the invention although such a
large operating angle is impractical.
In the normal working condition, the head portion 52
of drive roll 51 rotates in the direc-tion shown by a small arrow
105. The head portion 52 rotates through bearing means 80 around
doughnut ring 53 which is kept stationary during normal yarn winding
operation shown in Fig. 12~ The center "i" of the doughnut ring is
offset from the center "c" of the drive roll 51.
- During the normal yarn wind-up operation, drive roll 51
is kept in pressurized rolliny contact with the bobbin 2, yarn 100
is wound on the bobbin 2 in the transfer mode, and the head portion
52 is kept in separation from rubber bobbin end 58 with a certain
predetermined idle gap ~ shown in Fig. 12. The drive roll and the
bobbin have a common surface speed.
When this bobbin 2 reaches its fully wound state with
part of the yarn 100, it is carried away from this position and
the superseding bobbin 3 is brought to this position so as to
be synchronized wi-th the drive roll. Then, this roll must be accele-
rate~ to a substantially higher speed to accomplish reliable ~linding
operation of the now slackened part of the yarn 100. At this
stage, the doughnut ring is rotated 180 in the present i~ealized
condition around its offset center "c", thereby the rotational
center of head portion 52 shifti.ng relatively from "i" to "i "' as
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shown in Fig. 3. In this way, the head portion 52 is brought
into contact with rubber bobbin end 58, and the bobb;n is driven
at a substantially increased speed relative to the normal yarn
which is wound, while the drive roll and bobbin 3 are separated
from each other.
In the operation of the machine/ torque is transmitted
from the prime mover through successive members 70; 56b; 56a; 55;
51; 62; 63 and ~4 to head portion 52.
It is now assumed that a fully wound-up bobbin 2 has
been carried along from position and a new empty one 3 is brought
to position to synchronize with the friction drive roll 51 as shown
by way of example in Fig. 3. Then, the corresponding resilient
end portion as at S8 of the new ~obbin 3 will occupy a slightly
lower position than drive roll 51, thereby an idle gap ~ is
formed and maintained in Fig. 3, while the head portion 52 having
a lar~er diameter is kept in enga~ement with bobbin end 58 having
a smaller diameter. In this way and at this operational stage,
the bobbln 3 is driven at a higher rotational speed than usual with
an increase of at least 50%, so as to pick up the now slackened
yarn 100 which is supplied through the horizon-tally reciprocating
traverse 103 by the new bobbin 3 in a definite and positive manner.
At this stage, the pi,ston of compressed air cylinder
59, and its piston rod 59a, occupies its re-tracted position
corresponding to their full line position in Fig. 2 and to their
chain-dotted line position shown in Fig. 8, respectively. In
this way, the problem of yarn catch by the friction drive roll can
be avoided in a highly simplified way and without use of specially
provided complicated means.
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When the slac~ened yarn part of the constantly fed
yarn has been wound up substantially completely, compressed air
is introduced into the cylinder 59, so as to advance the piston
together with its rod 59a to the full line position thereo from
its former retracted imaginary line posi-tion 60' in Fig. 8.
Although the operating angle of operating arm 60 is shown as
about 60 in Fig. 8, this may vary to a lesser or larger degree,
dependlng upon the degree of eccentricity of the doughnut ring 53.
When piston rod 59a is brought in this way to its full
line position in Fig. 8, the head portion 52 of roll 51 will be
shifted to its chain-dotted line position 52' in Fig. 3, the
hitherto mutually contacting parts 58 and 52' are separated from
each other, while bobbin 3 and roll 51 are bxought to their
normally synchronizing and mutually contacting po~ition~ The
i result is that the bobbin is restored to its regular operating
condition rotating at its normally winding speed, until it will
attain its fuily wound state.
; The friction drive~roll 51 may have normally a diameter
just or substantially the same as that of the bobbin, or alternat-
ively, it may have a still larger diameter, as large as about three
times the bobbin diameter. The cylindrical surface o roll 51
may preferably be finished by polishing or galvanized with a hard
chromium coating. Line shaft 55 is rotatably mounted by means of
bearings 75b and 75a.
As shown in Fig. 1, a suspension wire or rope 25 extends
horiæontally from bobbin holder 1 and through a guide 26 rigidly
attached to machine frame 15 downwardly. To the forward end of the
rope 25, a mass of weight 27 is attached fixedly. By the provision
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of this weight suspension unit, it will be noted that the bobbin
holder 1 is always subjected to a mechanical pull acting in the
rightward direction seen in Fig. 1, therehy the bobbin which has
been brought to its operating position during bobbin exchange
period being kept in its proper pressure contact with the friction
drive roll through the intermediary of the bobbin holder.
It should be noted, however, in accordance ~lith our
practical experience, that during the bobbin exchange operation,
slip may occur occasionally between the resilient end 58 of a new
bobhin and the head portion 52 with use of such gravity pressure
system. In such case, the yarn lO0 may represent excess slackening
'n the yarn part extending between the departing fully wound bobbin
and the new one and in pursuit oE the attainment of the desired
rapid bobbin acceleration to at least a 50%-increase from the
regular winding speed, the result i5 frequently an entanglement of
the yarn around the drive roll 51.
In order to avoid such a problem, the related cooperating
parts 52 and 58 must be pressed against e~ch other with a
substantially accentuated pressure relative to the usual pressure
appearing in the normal yarn winding period. The increased pressure
may be two to th ee times greater than the usual pressure, and
must be applied directly after completion of each stepwise feeding
step necessary for a bobbin exchange operation by steppingly
rotating the bobbin holder l, so as to suppress the said kind of
slip .
For this purpose, a further fluid-opera-ted piston-and-
cylinder unit 28/ preferably operable with compressed air, is
fixedly attached to machine frame 15, so as to exert pressure on
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the cooperating parts 52 and 58, pushing them against each other.
This unit 28 has a movable piston rod 28a which is shown at its
retracted position in Fig. 1 by dotted lines.
When it is required, the unit 28 is activated with
pressure fluid, so as to advance the rod 28a rightwards to exert a
substantial internal pressure against the bobbin holder 1. At
each time when the stepwise rotational feed of the bobbin holder has
been completed and the yarn chan~e-over operation has also been
fully and satisfactorily executed, the unit 28 is instantly
deactivated by retracting the piston with its rod 28a, releasing
the bobbin holder from the application of lateral pressure. For
simplicity, inlet and outlet and their related conduit means have
been omitted from the dra~Ting, since the necessary dual purpose
structure is very well known to thbse skilled in the artO
- There is provided a still further fluid-operated piston-
cylinder unit 29 of the dual purpose type for stepping rotational
feed of the bobbin holder 1 which is pivotably moun-ted on a slide
10 and having a movable piston rod 29a linked at its forward end
with an arm 31a extending from a ratchet plate 31 arranged
20 concentrically with the bobbin holder 1, as shown most clearly in
Fig. 9. This ratchet plate 31 is further provided with a second
arm 31b arranged diametrally opposite to the said first arm 31a.
At the forward end of the second arm, a ratchet pawl 32 is pivotably
attacned. A brake element 34 is so arranged to cooperate with the
boss of ratchet plate 31, a coil spring 33 being provided so as to
urge the brake element to exert a brake pressure ayainst the said
ratchet plate boss.
When pressurized fluid is properly supplied to the
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cylinder unit ~9, which is shown at its contracted position in
Fig. 1, its piston, not shown, will advance together with its rod
29a. In this way, the latter will advance in rightwards and Upwards
in Figs. 1 and 9, thereby the ratchet pawl 32 kept in engagement
with one of notches 31a formed on the periphery surface of ratchet
plate 31 arranged concentrically with bobbin holder 1 pushing
forcibly the plate, so as to execute one step ro-tary feed of the
bobbin holder in counter clockwise direction for an angle of 90
in this embodiment. In this way, a new bobbin as at 3 is brought
into its operational position where the preceding and fully
wound bobbin 2 was situated and then is brought to its one-step
advanced position at 5 adapted or being removed from the bobbin
holder. The new bobbin 2 is brought into pressure engagement,
with drive roll 51. When this operation has been completed,
pressure fluid supply mode to the cylinder 29 is reversed, so as to
recede the piston rod 29a. Although not shown, bob~in holder 1
and ratchet plate 31 are joined together, so as to constitute a
unified member adapted for executing a unitary motion.
A still further fluid-operated piston-cylinder unit 36
of the dual purpose type is mounted on a slidable plate, not
shown, which is mounted in turn on the machine frame 15, said
unit having a piston rod 36a. This piston rod is provided with
an enlarged head 37 acting as a positioner adapted for cooperation
with any one of a series of radially arranged receiving recesses
as at 37a, on the periphery of said ratchet plate 31. In practice
and more specifically, this plate 31 has been made into a douhle-
plate structure, as most clearly be seen from Fig. 9. When the
~ositioner 37 is advanced, it is brought into one of said recesses
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37a, in order to ~ix the position of the plate 31. On the other
hand, when the positioner has been receded from its operating
position in engagement with said recess, the plate 31 is unlocked
for its free rotation.
In the following, the operation of the machine so ~ar
shown and described will be set ~orth in detail.
It is assumed that the yarn 100 was threaded from a
constant delivery supply source, not shown, through the traverse
103 and drive roll 51 to th~ bobbin 2, and indeed, in the transfer
mode so called, as ~ost clearly illustrated in Fig. 2 and that the
bobbin 2 has attained at its fully wound condition. Such ully
wound state of a bohbin can be sensed by auto~atically urging
electrically a timer on upon lapse of a certain predetermined time
period, such as 30 minutes counted from initiation of yarn winding
- of the same bobbin. ~f necessary, however, a co~bination o~ a
feeler adapted for sensing the yarn wound state o~ a bobbin, with
a microswitch arranged to be on-off controlled by the ~eeler, could
be utilized.
~en the said timer turns on, the cylinder unit 36 is
energized 50 as to recede the positioner 37 from position, thereby
other cylinder 29 being actuated by actuation of a limit switch
not shown, as shown in Fig. 10 illustrative of a ti~ing schedule
chart. When the cylinder 29 is thus activated, bobbin holder l is
caused to execute one step rotary feed in counter clockwise
direction in Fig. l and thus, the ~ully wound bobbin 2 is brought
into its of~-position at 5, while, at the same time a new bobbin
3 is brought to its working position in place of the foregoing
bobbin 2. During a predeter~ined short time period such as 0.3
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second as sho~ln in the timing schedule char-t, the new bobbin 3
is kept in its present state.
BeEore the elapse of this time period of 0.3 second,
a further timer which is not shown is turned on, and the
positioning cylinder 36 is actuated in its expanding stroke so that
the positioner 37 may be advanced into engagement wi-th one of
recesses 31c for Iocking the ratchet plate 31 and bobbin holder 1
at its newly divided position. Upon lapse of said time limit of
0.3 second, a still ~ur-~her timer, not shown, is caused to go on
and the initial pressurizing cylinder 28 is caused to ini~iate its
advancing stroke and further cvlinders 29 and 36 are caused to
initia~e their respective return strokes so as to recede their
piston rods 29a and 36a, thereby the pawl 32 being disengaged
~rom one o~ notches 31c. At the same time, the positioner 37 will
receae from its engaging position with one of the recesses 37a,
thereb~ ratchet plate 31 and bobbin holder being freed, whereupon
the contacting position between new bobbin 3 and friction drive roll
51 is maintained under the action of gravity weight mass 27.
With the same timing as that for the initial pressurizing
cylinder, the cylinder unit 59 for driving of the eccentric doughnut
is actuated, and the rubber bobbin end 58 and head portion 52 are
brought into mutual contact with each other, thereby a small idle
gap ~ being established maintained between the drlve roll and the
new bobbin. In this way, bobbin 3 is rotated in a substantially
accelerated way with an increased speed higher at least 50~ than
the usual yarn winding speed. At this operational stage, the
receded full-wound~bobbin 5 continues its winding operation ~or
~ur-ther take-up o~ yarn 100, however, with gradually decreasing
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speed. Thus, the yarn which is being fed always at a predetermined
constant speed regardless of the bobbin exchange operation will
become slackened as extending between the receded full-wound bobbin
and the new bobbin which has been brought to its newly yarn-winding
position cooperative with the friction drive roll.
By the actuation of initial pressurizing cylinder 28,
bob~in holder 1 is subjected to a rightwardly acting pressure when
seen in Fig. 1 and thus, the mutually contacting pressure between
new bobbin 3 and head portion 52 is suhstantially increased. Now,
the slackened yarn portion is wound on the new bobhin 3, the rotat-
ional speed of which is greatly, though temporarily,increased.
Then, the yarn will strongly be pulled between these two bobbins 2
and 3 until it is finally severed.
Immediately subseauent to the intentional severing of
the yarn the piston and its rod of the cylinder unit 59 will return
to their receded position representatively illustrated by the full
line position of the piston rod in ~ia. 2. In this way, the rubber
end of new bobbin 3 and the head portion are disengaged from each
other, while the drive roll and the new bobbin are brought into
mutual contact with each other. Then, -the initial ~ressurizing
cylinder 28 is brought to its receded piston position, thereby
initiating usual yarn winding at the normal winding speed.
~ Jith this improved s-tructural arrangement and its uniaue
operational mode, an auto-dofing operation can be done in a highly
simplified manner without the production o-f uneconomical and
troublesome waste yarn as is necessarily encountered with the
conventional comparative bobbin exchange system.
As represented in the foreqoing descrip-tion, the notches
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adapted for cooperation with the ratche-t pawl 32 and the recesses
adapted for cooperative engagement with the positioner 37 must have
the same operational phase; these no-tches and recesses may
preferably be made so they axe separated from each other as was
shown and described.
In the foregoing description, the yarn threading ~ode
was of the transfer mode. But, when necessary, the yarn may be
introduced into the co-engaging zone as provided between the bobbin
and friction drive roll, so as to execute the normal threading
mode. In this case, however, the stepwise rotational feed of the
bobbin holder should be reversed in its operational direction or
clockwise direction as shown in Fig. 1.
In addition, the machine may be designed in such way that
the posi-tloner 37, acting as a kind of a stop means may be caused
to disengage from its mating recess 37a when each bobbin has
attained its fully wound position.
To avoid the occurrence of a mechanical shock when the
positioner 37 engages its notch 37a to stop any rotational
movement of ratchet plate 31 and bobbin holder 1 by locking the
plate and the holder in position, the brake element 34 should
preferably be actuated directly before the lockinc~ operation.
In the following paragraphs, a practical numerical example
will be given to promote a clear understanding of the yarn change-
over operation.
Example
A conventionally used Spandex spinning liquor, viscosity:
2,500 p, was spun in the dry spinning process by use of dimethyl
formaldehyde as solvent, into a 40-denier yarn at a spinning speed
of 500 m/min. At -t'ne yarn winding zone, a machine of the ty e
i" ~
'1~5'~
shown and described in the foregoing paragraphs. Yarn change-over
operations were carried out so as to determine the likelihoocl of
a satisfactory yarn catch by a new empty bobbin kept at posltion,
and by transfer of the yarn from a fully wound bobbin. The
likelihood was measured upon completion oi a thousand tests for
each specifically selected test conditlon.
The friction drive roll was usecl in the form of a conven-
tional paper tube, having an outer diameter of 80 mm.
The minor idle gap ~ was set to 0.5 mm between the
friction drive roll and a new bobbin substituted by each bobbin
exchange operation. The operation of each of several main working
parts of the machine was synchronized with that which is listed in
the timing schedule chart shown in Fi~. 10. Five kinds of outer
diameter ratio between the head portion 52 and rubber bobbin end
58 were set to 1.2; 1.3; 1.4; 1.5 and 1.75, respectively, and the
; following results were obtained. The employment of the above ive
various ratios means that the winding speed during each bobbin
exchange was increased by 20~; 30%; 40%; 50~ and 75%, respectively,
relative to the normal winding speed.
Results
Rate of acceleration 20~ 30% 40% 50% 75%
Percentage of success
65-70 70-83 85-92 100 100
of yarn change-over, %
The less than perfect percentages of success were
caused in each case by yarn catch by the friction drive roll.
It will be seen from the foregoing paragraph that the
objects of this invention could be achieved by increasing the yarn
winding speed during bobbin exchange by at least 50% in comparison
with the normal yarn winding speed.
.
'1,,' ' ~j~ ~7W 1/.
