The Jute Industry: From Seed to Finished Cloth by T. Woodhouse and P. Kilgour
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T. Woodhouse and P. Kilgour >> The Jute Industry: From Seed to Finished Cloth
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spindle speed = delivery x twist.
There is thus a constant length of yarn to be wound on the rove
bobbin per minute, and the speed of the bobbin, which is driven
independently of the spindle and flyer, is constant for any one
series of rove coils on the bobbin. The speed of the bobbin differs,
however, for each complete layer of rove, simply because the
effective diameter of the material on the bobbin changes with the
beginning of each new layer.
The eyes of the flyers always rotate in the same horizontal plane,
and hence the rove always passes to the bobbins at the same height
from any fixed point. The bobbins, however, are raised gradually by
the builder during the formation of each layer from the top of the
bobbin to the bottom, and lowered gradually by the builder during
the formation of each layer from bottom to top. In other words, the
travel of the builder is represented by the distance between the
inner faces of the flanges of the rove bobbin.
[Illustration: FIG. 19 ROVING FRAME FAIRBAIRN'S ROVING FRAME IN WORK]
Since every complete layer of rove is wound on the bobbin in virtue
of the joint action of the spindle and flyer, the rotating bobbin,
and the builder, each complete traverse of the latter increases the
combined diameter of the rove and bobbin shaft by two diameters of
the rove. It is therefore necessary to impart an intermittent and
variable speed to the bobbin. The mechanism by means of which this
desirable and necessary speed is given to the bobbin constitutes one
of the most elegant groups of mechanical parts which obtains in
textile machinery. Some idea of the intricacy of the mechanism, as
well as its value and importance to the industry, may be gathered
from the fact that a considerable number of textile and mechanical
experts struggled with the problem for years; indeed 50 years
elapsed before an efficient and suitable group of mechanical parts
was evolved for performing the function.
The above group of mechanical parts is known as "the differential
motion," and the difficulties in constructing its suitable gearing
arose from the fact that the speed of the rove passing on to the
various diameters must be maintained throughout, and must coincide
with the delivery of yarn from the rollers, so that the attenuated
but slightly twisted sliver can be wound on to the bobbin without
strain or stretch. The varying motion is regulated and obtained by a
drive, either from friction plates or from cones, and the whole gear
is interesting, instructive--and sometimes bewildering--two distinct
motions, a constant one and a variable one, are conveyed to the
bobbins from the driving shaft of the machine.
The machine illustrated in Fig. 18 is of special design, and the
whole train of gear, with the exception of a small train of wheels
to the retaining roller, is placed at the pulley end--that nearest
the observer. The gear wheels are, as shown, efficiently guarded,
and provision is made to start or stop the machine from any position
on both sides. The machine is adapted for building 10 in. X 5 in.
bobbins, i.e. 10 in. between the flanges and 5 in. outside diameter,
and provided with either 56 or 64 spindles, the illustration showing
part of a machine and approximately 48 spindles.
The machines for rove (roving frames) are designated by the size of
the bobbin upon which the rove is wound, e.g. 10 in. x 5 in. frame,
and so on; this means that the flanges of the bobbin are 10 in.
apart and 5 in. in diameter, and hence the traverse of the builder
would be 10 in. The 10 in. x 5 in. bobbin is the standard size for
the ordinary run of yarns, but 9 in. x 4-1/2 in. bobbins are
used for the roves from which finer yarns are spun. When the
finished yarn appears in the form of rove (often termed spinning
direct), as is the case for heavier sizes or thick yarns, 8 in. x 4
in. bobbins are largely used.
Provision is made on each roving frame for changing the size of rove
so as to accommodate it for the subsequent process of spinning and
according to the count of the required yarn; the parts involved in
these changes are those which affect the draft gearing, the twist
gearing, and the builder gearing in conjunction with the automatic
index wheel which acts on the whole of the regulating motion.
CHAPTER X. SPINNING
The final machine used in the conversion of rove to the size of yarn
required is termed the spinning frame. The actual process of
spinning is performed in this machine, and, although the whole
routine of the conversion of fibre into yarn often goes under the
name of spinning, it is obvious that a considerable number of
processes are involved, and an immense amount of work has to be done
before the actual process of spinning is attempted. The nomenclature
is due to custom dating back to prehistoric times when the
conversion of fibre to yarn was conducted by much simpler apparatus
than it is at present; the established name to denote this
conversion of fibre to yarn now refers only to one of a large number
of important processes, each one of which is as important and
necessary as the actual operation of spinning.
A photographical reproduction of a large spinning flat in one of the
Indian jute mills appears in Fig. 20, showing particularly the wide
"pass" between two long rows of spinning frames, and the method
adopted of driving all the frames from a long line shaft. Spinning
frames are usually double-sided, and each side may contain any
practicable number of spindles; 64 to 80 spindles per side are
common numbers.
[Illustration: FIG 20. AN INDIAN SPINNING FLAT]
The rove bobbins, several of which are clearly seen in Fig. 20, are
brought from the roving frame and placed on the iron pegs of a creel
(often called a hake) near the top of the spinning frame-actually
above all moving parts of the machine. Each rove bobbin is free to
rotate on its own peg as the rove from it is drawn downwards by the
retaining rollers. The final drafting of the material takes place in
this frame, and a considerable amount of twist is imparted to the
drawn out material; the latter, now in the desired form and size of
yarn, is wound simultaneously on to a suitable size and form of
spinning bobbin.
When the rove emerges from the retaining rollers it is passed over a
"breast-plate," and then is entered into the wide part of the
conductor; it then leaves by the narrow part of the conductor by
means of which part the rove is guided to the nip of the drawing
rollers, The rove is, of course, drafted or drawn out between the
retaining and drawing rollers according to the draft required, and
the fibrous material, now in thread size is placed in a slot of the
"thread-plate," then round the top of the flyer, round one of the
arms of the flyer, through the eye or palm at the end of the flyer
arm and on to the spinning bobbin. The latter is raised and lowered
as in the roving frame by a builder motion, so that the yarn may be
distributed over the full range between the ends or flanges.
Each spindle is driven separately by means of a tape or band which
passes partially round the driving cylinder and the driven whorl of
the spindle, and a constant relation obtains between the delivery of
the yarn and the speed of the spindle during the operation of
spinning any fixed count or type of yarn. In this connection, the
parts resemble those in the roving frame, but from this point the
functions of the two frames differ. The yarn has certainly to be
wound upon the bobbin and at the same rate as it is delivered from
the drawing or delivery rollers, but in the spinning frame the bobbin,
which rotates on the spindle, is not driven positively, as in the
roving frame, by wheel gearing; each spinning bobbin is actually
driven by the yarn being pulled round by the arm of the flyer and
just sufficient resistance is offered by the pressure or tension of
the "temper band" and weight. The temper band is simply a piece of
leather or hemp twine to which is attached a weight, and the other
end of the leather or twine is attached to the builder rail.
[Illustration: FIG. 21 A LINE OF SPINNING FRAMES]
The front part of the builder rail is provided with grooves into one
of which the temper-band is placed so that the band itself is in
contact with a groove near the base of the bobbin flange. A varying
amount of resistance or tension on the bobbin is required in virtue
of the varying size of the partially-filled bobbin, and this is
obtained by placing the temper-band successively in different groves
in the builder so that it will embrace a gradually increasing arc of
the spinning bobbin, and thus impart a heavier drag or tension.
The spinning frames in Fig. 20 are arranged with the ends of the
frame parallel to the pass, whereas the end frames in Fig. 21 are at
right angles to the pass, and hence an excellent view of the chief
parts is presented. The full rove bobbins are seen distinctly on the
pegs of the creel in the upper part of the figure, and the rove
yarns from these bobbins pass downwards, as already described, until
they ultimately enter the eyes of the flyer arms to be directed to
and wound upon the spinning bobbins. The flyers--at one time termed
throstles--are clearly visible a little above the row of temper
weights. The chief parts for raising the builder--cam lever,
adjustable rod, chain and wheel--are illustrated at the end of the
frame nearest the observer.
CHAPTER XI. TWISTING AND REELING
In regard to cloth manufacture, most yarns are utilized in the form
they leave the spinning frame, that is, as single yarns. On the
other hand, for certain branches of the trade, weaving included, it
is necessary to take two, three, or more of these single yarns and to
combine them by a process technically termed twisting, and sometimes
"doubling" when two single yarns only are combined.
Although the commonest method, so far as weaving requirements go, is
to twist two single yarns together to make a compound yarn, it is
not uncommon to combine a much higher number, indeed, sixteen or
more single yarns are often united for special purposes, but, when
this number is exceeded, the operation comes under the heading of
twines, ropes and the like. The twist or twine thus formed will have
the number of yarns regulated by the levelness and strength required
for the finished product. The same operation is conducted in the
making of strands for cordage, but when a number of these twines are
laid-up or twisted together, the name cord or rope is used to
distinguish them.[1]
[Footnote 1: See _Cordage and Cordage Hemp and Fibres_, by T.
Woodhouse and P. Kilgour.]
When two or three threads are united by twisting, the operation can
be conducted in a twisting frame which differs little from a
ordinary spinning frame, and hence need not be described. There may
be, however, appliances embodying some system of automatic stop
motion to bring the individual spindles to rest if one thread out of
any group which are being combined happens to break. When several
threads have to be twisted together, special types of twisting
frames are employed; these special machines are termed "tube twisters,"
and the individual threads pass through holes suitably placed in a
plate or disc before they reach the tube.
More or less elaborate methods of combining yarns are occasionally
adopted, but the reader is advised to consult the above-mentioned
work on Cordage and similar literature for detailed information.
When the yarn leaves the spinning frame, or the twisting frame, it
is made up according to requirements, and the general operations
which follow spinning and twisting are,--reeling, cop-winding, roll
or spool winding, mill warping or link warping. The type or class of
yarn, the purpose for which the yarn is to be used, or the equipment
of the manufacturer, determines which of these methods should be
used previous to despatching the yarn.
_Reeling_. Reeling is a comparatively simple operation, consisting
solely of winding the yarns from the spinning or twisting bobbins on
to a wide swift or reel of a suitable width and of a fixed diameter,
or rather circumference. Indeed, the circumference of the reel was
fixed by an Act of Convention of Estates, dating as far back as 1665
and as under:
"That no linen yarn be exported under the pain of confiscation, half
to the King and half to the attacher."
"That linen yarn be sold by weight and that no reel be shorter than
_ten quarters_."
The same size of reel has been adopted for all jute yarns. All such
yarns which are to be dyed, bleached, or otherwise treated must be
reeled in order that the liquor may easily penetrate the threads
which are obviously in a loose state. There are systems of dyeing
and bleaching yarns in cop, roll or beam form, but these are not
employed much in the jute industry. Large quantities of jute yarns
intended for export are reeled, partly because bundles form suitable
bales for transport, and partly because of the varied operations and
sizes of apparatus which obtain in foreign countries.
YARN TABLE FOR JUTE YARNS
90 inches, or 2-1/2 yards = 1 thread, or
the circumference of the reel
120 threads or 300 yards = 1 cut (or lea)
2 cuts or 600 yards = 1 heer
12 cuts or 3,600 yards = 1 standard hank
48 cuts or 14,400 yards = 1 spyndle
Since jute yarns are comparatively thick, it is only the very finest
yarns which contain 12 cuts per hank. The bulk of the yarn is made
up into 6-cut hanks. If the yarn should be extra thick, even 6 cuts
are too many to be combined, and one finds groups of 4 cuts, 3 cuts,
2 cuts, and even 1 cut. A convenient name for any group less than 12
cuts is a "mill-hank," because the number used is simply one of
convenience to enable the mill-hank to be satisfactorily placed on
the swift in the winding frame.
The reeling operation is useful in that it enables one to measure
the length of the yarn; indeed, the operation of reeling, or forming
the yarn into cuts and hanks, has always been used as the method of
designating the count, grist or number of the yarn. We have already
seen that the count of jute yarn is determined by the weight in lbs.
of one spyndle (14,400 yds.).
For 8 lb. per spyndle yarn, and for other yarns of about the same
count, it is usual to have provision for 24 spinning bobbins on the
reel. As the reel rotates, the yarn from these 24 bobbins is wound
round, say,
6 in. apart, and when the reel has made 120 revolutions, or 120
threads at each place from each bobbin, there will be 24 separate
cuts of yarn on the reel. When 120 threads have been reeled as
mentioned, a bell rings to warn the attendant that the cuts are
complete; the reel is then stopped, and a "lease-band" is tied round
each group of 120 threads.
A guide rod moves the thread guide laterally and slowly as the
reeling operation is proceeding so that each thread or round may be
in close proximity to its neighbour without riding on it, and this
movement of the thread extends to approximately 6 in., to accommodate
the 6 cuts which are to form the mill-hank.
Each time the reel has made 120 revolutions and the bell rings, the
reeler ties up the several cuts in the width, so that when the
mill-hank is complete, each individual cut will be distinct. In some
case, the two threads of the lease-band instead of being tied, are
simply crossed and recrossed at each cut, without of course breaking
the yarn which is being reeled, although effectively separating the
cuts. At the end of the operation (when the quantity of cuts for the
mill-hank has been reeled) the ends of the lease-band are tied.
The object of the lease-band is for facilitating the operation of
winding, and for enabling the length to be checked with approximate
correctness.
When the reel has been filled with, say, twenty-four 6-cut hanks,
there will evidently be 3 spyndles of yarn on the reel. The 24
mill-hanks are then slipped off the end of the reel, and the hanks
taken to the bundling stool or frame. Here they, along with others
of the same count, are made up into bundles which weigh from 54 lb.
to 60 lb. according to the count of the yarn. Each bundle contains a
number of complete hanks, and it is unusual to split a hank for the
purpose of maintaining an absolutely standard weight bundle. Indeed,
the bundles contain an even number of hanks, so that while there
would be exactly 56 lb. per bundle of 7 lb. yarn, or 8 lb. yarn,
there would be 60 lb in a bundle of 7-1/2 lb. yarn, and 54 lb.
in a bundle of 9 lb. yarn.
The chief point in reeling is to ensure that the correct number of
threads is in each cut, i.e. to obtain a "correct tell"; this ideal
condition may be impracticable in actual work, but it is wise to
approach it as closely as possible. Careless workers allow the reel
to run on after one or more spinning bobbins are empty, and this
yields what is known as "short tell." It is not uncommon to
introduce a bell wheel with, say, 123 or 124 teeth, instead of the
nominal 120 teeth, to compensate for this defect in reeling.
CHAPTER XII. WINDING: ROLLS AND COPS
The actual spinning and twisting operations being thus completed,
the yarns are ready to be combined either for more elaborate types
of twist, or for the processes of cloth manufacture. In its simplest
definition, a fabric consists of two series of threads interlaced in
such way as to form a more or less solid and compact structure. The
two series of threads which are interlaced receive the technical
terms of warp and weft--in poetical language, warp and woof. The
threads which form the length of the cloth constitute the warp,
while the transverse threads are the weft.
The warp threads have ultimately to be wound or "beamed" on to a
large roller, termed a weaver's beam, while the weft yarn has to be
prepared in suitable shape for the shuttle. These two distinct
conditions necessitate two general types of winding:
(_a_) Spool winding or bobbin winding for the warp yarns.
(_b_) Cop winding or pirn winding for the weft yarns.
For the jute trade, the bulk of the warp yarn is wound from the
spinning bobbin on to large rolls or spools which contain from 7 to
8 lb. of yarn; the weft is wound from the spinning bobbin into cops
which weigh approximately 4 to 8 ounces.
Originally all jute yarns for warp were wound on to flanged bobbins
very similar to, but larger than, those which are at present used
for the linen trade. The advent of the roll-winding machine marked a
great advance in the method of winding warp yarns as compared with
the bobbin winding method; indeed, in the jute trade, the latter are
used only for winding from hank those yarns which have been bleached,
dyed or similarly treated. Fig. 22 illustrates one of the modern
bobbin winding machines for jute made by Messrs. Charles Parker,
Sons & Co., Dundee. The finished product is illustrated by two full
bobbins on the stand and close to a single empty bobbin. There are
also two full bobbins in the winding position, and several hanks of
yarn on the swifts. Each bobbin is driven by means of two discs, and
since the drive is by surface contact between the discs and the
bobbin, an almost constant speed is imparted to the yarn throughout
the process. An automatic stop motion is provided for each bobbin;
this apparatus lifts the bobbin clear of the discs when the bobbin
is filled as exemplified in the illustration.
The distance between the flanges of the bobbin is, obviously, a
fixed one in any one machine, and the diameter over the yarn is
limited. On the other hand, rolls may be made of varying widths and
any suitable diameter. And while a bobbin holds about 2 lb. of yarn,
a common size of roll weighs, as already stated, from 7 to 8 lb.
Such a roll measures, about 9 in. long and 8 in. diameter; hence for
8 lb. yarn, the roll capacity is 14,400 yards.
Rolls very much larger than the above are made on special machines
adopted to wind about six rolls as shown in Fig. 23. It is built
specially for winding heavy or thick yarns into rolls of 15 in.
diameter and 14 in. length, and this particular machine is used
mostly by rope makers and carpet manufacturers. One roll only is
shown in the illustration, and it is winding the material from a 10
in. x 5 in. rove bobbin. The rove is drawn forward by surface or
frictional contact between the roll itself and a rapidly rotating
drum. The yarn guide is moved rapidly from side to side by means of
the grooved cam on the left, the upright lever fulcrumed near the
floor, and the horizontal rod which passes in front of the rolls and
upon which are fixed the actual yarn guides. This rapid traverse,
combined with the rotation of the rolls, enables the yarn to be
securely built upon a paper or wooden tube; no flanges are required,
and hence the initial cost as well as the upkeep of the foundations
for rolls is much below that for bobbins.
[Illustration: _By permission of Messrs. Charles Parker, Sons & Co_.
FIG. 22 BOBBIN WINDING MACHINE WITH HANKS]
Precisely the same principles are adopted for winding the ordinary 9
in. x 8 in. or 8 in. x 7 in. rolls for the warping and dressing
departments. These rolls are made direct from the yarn on spinning
bobbins, but the machines are usually double-sided, each side having
two tiers; a common number of spools for one machine is 80.
The double tier on each side is practicable because of the small
space required for the spinning bobbins. When, however, rolls are
wound from hank, as is illustrated in Fig. 24, and as practised in
several foreign countries even for grey yarn, one row only at each
side is possible. Both types are made by each machine maker, the one
illustrated in Fig. 24 being the product of Messrs. Charles Parker,
Sons & Co., Dundee.
In all cases, the yarns are built upon tubes as mentioned, the
wooden ones weighing only a few ounces and being practically
indestructible, besides being very convenient for transit; indeed it
looks highly probable that the use of these articles will still
further reduce the amount of yarn exported in bundle form.
[Illustration: FIG. 23 ROLL WINDER FOR LARGE ROLLS _By permission of
Messrs. Douglas Fraser & Sons, Ltd_.]
The machine illustrated in Fig. 24, as well as those by other makers,
is very compact, easily adjustable to wind different sizes of rolls,
can be run at a high speed, and possesses automatic stop motions,
one for each roll.
A full roll and a partially-filled roll are clearly seen. A recent
improvement in the shape of a new yarn drag device, and an automatic
stop when the yarn breaks or the yarn on the bobbin is exhausted,
has just been introduced on to the Combe-Barbour frame.
[Illustration: FIG. 24 ROLL WINDING MACHINE (FROM HANKS) _By
permission of Messrs. Charles Parker, Sons & Co_.]
Weft Winding. A few firms wind jute weft yarn from the spinning
bobbins on to pirns (wooden centres). The great majority of
manufacturers, however, use cops for the loom shuttles. The cops are
almost invariably wound direct from the spinning bobbins, the
exception being coloured yarn which is wound from hank. There are
different types of machines used for cop winding, but in every case
the yarn is wound upon a bare spindle, and the yarn guide has a
rapid traverse in order to obtain the well-known cross-wind so
necessary for making a stable cop. The disposition of the cops in
the winding operation is vertical, but while in some machines the
tapered nose of the cop is in the high position and the spinning
bobbin from which the yarn is being drawn is in the low position, in
other machines these conditions are opposite. Thus, in the cop
winding frame made by Messrs. Douglas Fraser & Sons, Ltd., Arbroath,
and illustrated in Fig. 25, the spinning bobbins are below the cops,
the tapered noses of the latter are upwards in their cones or shapers,
and the yarn guides are near the top of the machine. This view shows
about three-fourths of the full width of a 96-spindle machine, 48
spindles on each side, two practically full-length cops and one
partially built. The illustration in Fig. 26 is the above-mentioned
opposite type, and the one most generally adopted, with the spinning
bobbins as shown near the top of the frame, the yarn guides in the
low position, and the point or tapered nose of the cop pointing
downwards. Six spindles only appear in this view, which represents
the machine made by Messrs. Urquhart, Lindsay & Co., Ltd., Dundee,
but it will be understood that all machines are made as long as
desired within practicable and economic limits.
[Illustration: _By permission of Messrs. Douglas Fraser & Sons, Ltd_.
FIG. 25 COP WINDING MACHINE]
The spindles of cop machines are gear driven as shown clearly in Fig.
26; the large skew bevel wheels are keyed to the main shaft, while
the small skew bevel wheels are loose on their respective spindles.
The upper face of each small skew bevel wheel forms one part of a
clutch; the other part of the clutch is slidably mounted on the
spindle. When the two parts of the clutch are separated, as they are
when the yarn breaks or runs slack, when it is exhausted, or when
the cop reaches a predetermined length, the spindle stops; but when
the two parts of the clutch are in contact, the small skew bevel
wheel drives the clutch, the latter rotates the spindle, and the
spindle in turn draws forward the yarn from the bobbin, and in
conjunction with the rapidly moving yarn guide and the inner surface
of the cone imparts in rapid succession new layers on the nose of
the cop, and thus the formed layers of the latter increase the
length proportionately to the amount of yarn drawn on, and the
partially completed cop moves slowly away from its cup or cone until
the desired length is obtained when the spindle is automatically
stopped and the winding for that particular spindle ceases. Cops may
be made of any length and any suitable diameter; a common size for
jute shuttle is 10 in. long, and 1-5/8 in. diameter, and the
angle formed by the two sides of the cone is approximately 30 degrees.
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