Note: Descriptions are shown in the official language in which they were submitted.
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1 This invention relates to a machine for acting on
- continuously running textile yarns. In British Patent No.
137 124~ there is described a crimping machine which has an
improved doffing system. The present invention is applicable
to a false twisting machine, and also to other machines acting
on continuous running flexible yarns, for example machines
for re-winding yarn from one package to another.
The doffing system in the aforesaid British Patent has
doffer tubes one inch (25mm) in diameter and tubes used pre-
viously have usually been from about 25 mm up to 50 mm indiameter. Such relatively large tubes have always been thought
necessary in order to prevent drag, i.e. frictional losses,
and to ensure sufficient air flow to generate adequate tension
in a yarn being doffed. It has never been thought possible
to use smaller tubes, although this would be desirable as
they are cheaper and take up less space on the machine.
Surprisingly, we have found that it is possible to use
tubes smaller than 25 mm diameter, provided the size of the -~
apertures therein is carefully controlled, and provided a
lower diameter limit is not passed. This lower limit is set
by the increasing costs of handling and machining small stock.
Still further surprising is that the smaller tubes give
greater yarn tension then previous systems-and the system
using the smaller tubes requires substantially less power than ~ '!"' ''
known systems. This means that running costs are less.
The present invention provides a machine for acting
on continuously-running yarn wherein a doffer system is
provided having an exhauster including a prime mover, fan and
filter, a plurality of tubes, each extending along the machine
and each having a plurality of spaced-apart apertures each
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1 normally closed by a sleeve of resilient material slidable
along the tube, wherein each tube has an internal diameter
between 10 and 20 mm and the area ratio (that is the area of
each aperture to the internal cross-sectional area of the
tube) is greater than 30%. Preferably the area of each
aperture lies between 30% and 100% of the cross-sectional
area of the tube.
Preferably each aperture has an area between 50% and
70% of the internal area of the tube, which advantageously
has an internal diameter from 15 to 17 mm.
The invention will be described further, by way of
example, with reference to the accompanying drawings,
wherein:
Fig. 1 is a general arrangement of a known doffer
system of a texturising machine; ~ ~-
Fig. 2 is a detail of the portion ringed in Fig.l;
Fig. 3 is a general arrangement of a doffer system
of a preferred embodiment of machine of the invention, again ; -
a textilising machine;
Fig. 4 is an enlarged fragmentation detail, part
sectional, of the left-hand ringed portion of Fig. 3;
Flg. S is a similar detail of the right-hand ringed
portion of Fig. 3; and
Fig. 6 is a view similar to that of Fig. 4, but ~ -
showing a variant.
Referring firstly to Figs. l and 2, it will be seen -
that a known doffer system on a texturising machine (indicated
in dotted lines) has an exhauster lO and a pair of doffer
tubes ll extending the full length of the machine. Each tube
is about 25 mm in outside diameter (22 mm inside diameter) and
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1 has a plurality of apertures 12 spaced therealong, each about
12 mm in diameter. Each aperture is normally sealed by a res-
pective sleeve 13 whose body is of resilient material so that it
can sealingly engage the edges of the aperture 12 to prevent
leakage of air into the tube 11. The area of each aperture is
about 33% of the cross sectional area of the tube. The exhauster
10 comprises a yarn receiving compartment 14, a yarn arrester
15, a fan 17 and an electric motor 16. The exhauster 10 is a
rectangular casing about 900 mm x 850 mm x 450 mm and the
tO motor 16 is rated at 5.5 horsepower (4103 watts).
Turning now to Figs.3 to 6 of the drawings, a doffer
system 20 of a preferred embodiment of machine of the invention
(a texturising machine similar to that described in British
- Patent Specification No. 1371244) whose central structure is
indicated in dotted lines, has an exhauster 21. Exhauster 21
is similar in constuction to exhauster 10, having a yarn-
receiving compartmènt, yarn arrester, fan and electric motor
(all not shown). The exhauster 21 is contained within a casing
which is about 600 mm x 750 mm x 350 mm, i.e. has less than
2Q half the volume of exhauster 10. The motor of exhauster 21
has a rating of 3 horsepower (2238 watts), that is less than
55~ of the rating of the motor of exhauster 10. The fan
typically has characteristics of 2300 mm WG at zero volume and
about 260 cu.m per minute at zero suction.
Doffer tubes 22 extend along the length of the machine
and each has spaced apart apertures 23 normally closed by
sleeves 23 similar to sleeves 13. The apertures 23 combe
slots 24 (as in Fig. 4) or circular holes 25 (as in Fig. 6).
This point will be discussed later. Each doffer tube 22 is
connected via a special L-shaped elbow 26 to a flexible tube
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1 27, of larger diameter than the doffer tube 22, which connects
with the exhauster 21. Tube 27 is greater in diameter than
the doffer tube 22 in order to reduce the possible friction :
between yarn and the flexible tube 27. Elbow 26 (Fig. 5)
has a first limb 28,of diameter equal to the diameter of
doffer tube 22 connecting with a second limb 29, at right
angles to the first limb 28, of the same diameter of the
first limb 28 to the diameter of tube 27. The upper end of the
second limb 29 is closed except for a central aperture 30,
which allows increased air flow through tube 27 to compensate
for the increased diameter thereof so to maintain the air
velocity the same in tube 27. Where the limb 28 meets limb 29,
a short extension 31 is provided which forms a yarn guide
- to maintain yarn 32 central in the two limbs and reduce friction
as it changes direction. .
The size of doffer tubes 22 which have been used are
(A) nominal 3/4 inch and (B) nominal 5/8 inch tubes which have
internal diameters of approximately 17 and 15 mm respectively.
Circular apertures about 9.5 mm in diameter have been used -
(a) as well as slots 9.5 x 15.8 mm (b) and 9.5 x 22.2 mm lc).
Apertures (a) have been used in relation to tube B, when the
area ratio (area of aperture/area of tube) % was abaut 37%.
Apertures (b) and (c) have been used with tube A, when the
- area ratio was 66~ and 97%. All combinations of the given :
apertures and tube sizes can be used, however, but combination
(c) B gives an area ratio of 150%, which is not preferred,
because no significant increase in yarn tension is obtained
with an area ratio greater than 100~. :
Slots are preferred in most instances, because for the
same area they extend over more of the length of the tube and ;
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1 it is therefore easier for an operative to 'hit' the aperture
when he 'throws' a yarn to be doffed.
The yarn tension obtained with the doffer system on
the machine of the invention is considerably greater than that
obtained with the known doffer system, a typical increase,
under comparable conditions, being about ~0%. The new doffer
system also has considerable advantages in threading up the
machine. During threading up, the operative leads a yarn from
the heater of the machine, through the non-rotating spinner,
and to the doffer tube. This yarn must be moved past the -
heater at its running speed to avoid melting of the yarn by
the heater and fouling of the latter. Because the spinner
is not operating the yarn being doffed is 'flat', i.e. is not
texturised, and thus is not so easily "gripped" by the air-
stream. Thus the increased tension applied by the new doffer
system greatly speeds up the threading of the machine and
so considerably reduces machine downtime.
The invention is not limited to the foregoing and
variations can be made thereto. For example the machine does
not have to be a texturising machine and can be any ~achine
acting on continuously-running yarn, such as a machine for
re-winding yarn from one package to another.
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