Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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(3655)
DRAW MODULE
BACKGROUND OF THE INVENTION
This invention generally relates to the art of produc-
ing or processing man-made fibres and specifically to draw-
ing of such fibres as a part of a melt-spinning production
method or as a separate processing step.
Generally, drawing of man-made fibres, i.e. those con-
sisting essentially of a synthetic or semi-synthetic
polymer material, such as a nylon, polyester or polyalky-
lene, comprises an elongation of the fibre in solid state
- so as to achieve molecular orientation, or crystallization,
of the fibres generally leading to an increased tensile
strength and to obtain a "low oriented", "partially
oriented" or "high oriented" yarn (LOY, POY and FOY,
respectively) depending upon the degree of orientation
achieved in one or more drawing stages.
Drawing may involve heating of the fibres by con-
vection or contact and a typical conventional draw module
comprises a number of subsequent drawing stages, each stage
- involving a passage of the yarn, typically in the form of
one or more multi-filament strands, around a pair of
adjacent rollers in which the "down-stream" roller rotates
~5 at a higher peripheral speed than the "up-stream" roller of
each pair.
:
The terms "up-stream" and "down-stream" as used herein
are relative terms and refer to a position closer to, or
more removed from, the infeed portion of the drawing
process or apparatus. In other words, yarn at an up-stream
portion of the process or apparatus will have a relatively
lower degree of orientation than at a more down-stream
portion of the same process or apparatus.
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A main problem in any continuous process involving
treatment of filaments, man-made or otherwise, is rupture
or breakage of the yarn, and various means are known for
-~ maintaining continuous plant operation upon breakage of a
filament or yarn in an apparatus in which a number of
filaments or yarns is processed simultaneously. Typically,
the path of the yarn, strand or filament is provided with
several control and "deviating devices" which will trap and
carry away the continuously supplied up-stream end portion
of the yarn, strand or filament after a break.
It should be noted that the terms i'yarn" and "strand"
as used herein both refer to a continuous structure
composed of a plurality of monofilaments, the difference
being one of a differing degree of entanglement in the
sense that a strand will have little or no mutual entangle-
ment, intertwining, twisting or the like of the essentially
parallel filaments whereas as typical yarn will show less
or no parallel alignment of the filaments that constitute
the yarn. However, as the degree of parallel alignment, on
the one hand, and entanglement, intertwining, twisting or
the like, on the other hand, of the filaments of a strand
or yarn is believed to be of subordinated importance
herein, the term strand is assumed to encompass yarns, and
vice versa.
Accordingly, whenever the term "strand" is used herein
below, it will encompass strands with any degree of
parallel alignment of its filaments as well as strands
wherein the filaments show entanglement, intertwining,
twisting or the like.
Generally, deviation of a broken filament or strand is
effected by a stationary suction nozzle that catches and
swallows, generally by suction, the broken end of the up-
stream portion and continues to remove that filament or
strand yarn portion into a yarn waste bin until an operator
supplied with a cutter and mobile suction device severs the
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filament or strand at a point before its entry into the
deviating device and proceeds to "draw" the broken filament
or strand down-stream and around or throuyh any subsequent
stages of the processing method ox apparatus. For this
reason and to provide access to all portions of a multi-
stage draw module, the roller pairs are arranged in a
staggered or stepped arrangement so that any downstream
roller pair protrudes beyond the adjacent up-stream roller
pair by an axial offset corresponding essentially to the
"operative width" or of the down-stream roller pair. The
term "operative width" as used herein refers to that part
of the axial length of a roller, or roller pair, which is
in direct physical contact with the windinys of the
filament or strand.
While such prior art multi-stage draw modules are
available commercially, e.g. as Draw Module Multisystem
from Filteco s.p.a of Cerrio Maggiore, Milano, Italy, and
have been well received by the industry because of
favourable performance properties and applicability to
various processing environments, they tend to have a rela-
tively large overall "size", "width" or "depth" i. e. that
dimension of the draw module that increases with each
roller pair by the operative width of that roller pair, and
this may be a major disadvantage when operating space is at
a premium.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is a main object of the invention to
provide for a multi-stage draw module where the "depth" or
"width" dimension of the apparatus does not increase by
another operative width when another roller pair is added,
but without any sacrifice of accessibility of the draw
rollers for breakage repair in the conventional manner.
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It is a further object of the invention to improve the
ease of access of and to a multi-stage draw module for pur-
poses of maintenance or repair without the need to use ex-
ternal aids, such as scaffolds, ladders or the like means
Now, according to the present invention, these main
objects as well as further advantages explained in more
detail below will be achieved by a novel draw-module of the
type having a number of draw roller pairs, e.g. from 2 to 6
roller pairs or eYen more, comprising at least one upper
and at least one lower draw roller pair in a staggered
arrangement relative to a theoretical plane of reference,
each draw roller pair including two rollers having essenti-
ally parallel axes and essentially the same axial length,
and all draw roller pairs having essentially parallel axes
arranged substantially perpendicularly to said plane of
reference; said staggered arrangement of said draw roller
pairs being defined essentially by a longitudinal offset of
each of said upper draw roller pair relative to an adjacent
lower draw roller pair, said offset corresponding essen-
tially with the operative width, or strand-contacting axial
length, of an upper draw roller pair; according to a
general feature of the invention, the said theoretical
plane of reference has an inclination of between about 20
and about 60 degree relative to a horizontal plane,
preferably of bout 35 degree.
EXPLANATION OF THE DRAWINGS
:.
The invention will be better understood and further
objects will become apparent when considering the enclosed
drawings in which:
Fig. 1A is a semi-diagrammatic side view of a prior
art multi-stage draw module with a plurality of
axially off-set draw roller pairs;
Fig 1B is a front view of the prior art draw module
shown in Fig. 1A;
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Fig. 2A is a semi-diagrammatic side view of a pre-
ferred embodiment of the novel draw module according
to the invention; and
Fig. 2B is`a front view of the draw module shown in
Fig. 2A.
The prior art draw module 10 shown semi-diagrammati-
cally in a side view in Fig. 1A comprises a frame 11
provided with three draw roller pairs 12, 13 and 14 and a
feed-in roller device 15 for passing and drawing four
multifilament strands S fed into draw module 10 at the
upstream end via a conventional breakage control and
deviating device 16. The preceding apparatus portion (not
shown) or process step could be a conventional melt-
spinning apparatus or a yarn packaye holder (not shown). A
take-up device or winder 18 is provided at the downstream
end of module 10, preferably including a conventional
intermingling device. Strand guides 171 and 172 are
provided to control the travel path of each multifilament
strand. While only one draw roller 121, 131 and 141 is
shown in Fig. 1A it will be appreciated that the axes of
all roller except the holding roller 152 of the entry
roller device 15 are arranged in parallel and include an
angle of about 90 degree with a theoretical reference plane
P1 which, in turn, is essentially arranged vertically, i.e.
perpendicular in that it includes an angle ~1 of about 90
; degree with the horizontal. In other words, the term
"staggered arrangement relative to a theoretical plane of
reference" is understood as referring a theoretical plane
positioned at an angle of about 90 relative to the axes of
the draw rollers.
It should be noted that the infeed roller-device 15
having a larger roller 151 and a slightly inclined smaller
roller 152, such arrangement can well be replaced with a
pair of parallel rollers of the same or a different
diameter as roller 151. Regardless of wether a pair of
equally dimensioned parallel rollers or the dissimilar-pair
~; 5
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arrangement 151, 1~2 shown in Fig lA is used, it is
apparent from Fig.lA that each 'Idown-stream'' roller pair
(actually the roller pair in the 'lupperll position in Fig.
lA) is offset in an axial direction relative to the
preceding l'lower" or "upstream" pair by the working "width"
(axial roller length covered by windings of the strands) of
the preceding upstream roller pair.
, .
It is only by such a staggered or stepped arrangement
of the draw roller pairs that an operator can draw the
"end" of a broken strand downstream onto the next roller
pair since otherwise the strand portions would have
to"cross" each other which is not only impractical but
operatively unfeasible. Obviously, the "end" of the broken
strand is not a stationary portion of a strand but a
dynamically changing strand portion defined ~y the "type"
of the mobile suction device (not shown) used by the
operator when "mending" the path of a broken strand.
When considering Fig. 1B in conjunction with Fig.1A it
is apparent that both rollers of each pair 12, 13 and 14
have the same diameters, are of the same length, and are
arranged in parallel within each pair and between all
pairs, again with the exception of an angularly displaced
infeed roller 151 when such a feeding device is actually
~ used (as shown in the drawings). Since draw modules of the
;~ 25 type shown in Fig. 1A, 1B are known in the art, a detailed
discussion of further components is omitted herein for
brevity. It should be noted however, that conventional
drives for the draw rollers will be used (not shown in the
drawings~) in accordance with the power requirements and the
draw ratios required for any given situation. Also, some or
all draw rollers may be heated in a conventional manner if
this is advantageous for any given application.
The novel draw module illustrated in Fig. 2A and 2B is
composed essentially of the same or similar elements and
this is indicated in the figures by using the same second
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digits in the reference numerals and changing only the
first digit in accordance with the numbering of the
figures. The main difference regarding element structure
resides in the roller supports which are essentially
S regular cylindrical in Figs. lA and 1~ (120,130,140) while
they are irregular cylinders in Fiqs. 2A and 2B in that the
axial mantle lines at the upper portions of the supports
220, 230, 240 are substantially shorter than the axial
mantle lines of the lower support portions.
Notwithstanding the relatively minor structural
modification of the draw roller supports apparent from a
comparison of Figs. 1A,1B on the one hand, and Figs. 2A,
2B, on the other, the overall effect is substantial:
because the theoretical plane P2 of reference according to
the invention is not vertical or perpendicular but includes
an angle ~2 of about 20 to about 60 degree with the
horizontal, the staggered arrangement and axial offset of
the drawing roller pairs 22, 23, 24 as well as the larger
roller 251 of the feeding roller device 25 needed for
- 20 access by an operator when re-feeding a broken strand by
means of a mobile suction device through all downstream
stations is maintained while the lateral "width" or "depth"
of a draw ~odule according to the invention is not only
substantially shorter than a comparable prior art machine
but does not increase in depth if one or more additional
draw roller pairs are added, and achieving such reduction
at no sacrifice of accessibility for conventional strand
breakage repair.
It is higly preferred according to the invention that,
in addition to the change of angular position of the axes
of substantially all draw rollers, substantially all draw
roller axes should be essentially in parallel alignment.
More specifically, maximum deviation from such parallelity
should be less than 10 and preferably not more than about
5.
:
:
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It is apparent from the drawing~ that the "working
width" of each roller of each draw roller pair, i. e. the
axial length thereof that is essentially covered with the
strand windings, is almost equal to the actual length of
the rollers and corresponds typically to at least about 80
of the actual length. This is preferred for practical pur-
` poses and optimum efficiency.
Generally, the draw module according to the
invention can be operated essentially under the same
conditions as comparable prior art machines and, according-
ly, a more detailed discussion of operational details is
omitted for brevity,
,:
The obvious and substantial advantages of a draw
module according to the invention when compared with a
prior art apparatus of the same capacity are believed to be
an indication of the unobviousness of the invention as dis-
closed herein. It will be understood that the above showing
of a preferred embodiment of the invention as illustrated
; in Figs. 2A and 2B is not intended to limit the invention
and that many modifications within the scope of the
inventive teaching will be apparent to those skilled in the
art.
