THE PREPARING AND SPINNING MACHINERY FOR HEMP AND OTHER SOFT FIBRES
Since there is such a great variety of ropes, cords and twines, not only
in regard to diameters, but also in regard to the different fibres used
in the manufacture of these goods, it is not surprising to find that
there are many different kinds of machines involved in the various
operations; some of these machines are introduced for the special
purpose of reducing the fibres to practicable lengths, but these
machines are, of course, used only for the type of fibres which exceed
about 36 in. On the other hand, it is sometimes found desirable to cut
certain types of fibres which do not exceed the limits demanded by the
capacity of the machines, but this is done only as a selective operation
to obtain the best and strongest part of the fibre.
While certain classes of soft fibres such as Russian, French, Chinese
and Indian hemps may be used without any previous hackling operation in
the spinning of certain sizes of cordage, it is found that Italian,
Serbian, Roumanian and Neapolitan hemps must be cut into suitable
lengths and hackled before they can be passed through the preparing
machines; in these latter machines the fibres are arranged into a
practicable condition before they are subjected to the actual spinning
operation.
The production of yarn for use in the making of cotton driving ropes
involves the use of the whole system of cotton-spinning machinery,
while, on the other hand, hemp yarns, besides being prepared
mechanically, are still produced by a series of the simplest and oldest
methods of hand hackling and hand spinning.
Fine ropes and twines may be, and often are, produced by an elaborate
system of machinery, and modified forms of such a system, in which a
smaller number of machines are employed, may be adopted for the spinning
of the heavier yarns.
A complete plant for the manufacture of these yarns from soft fibres
would include the following--
Softening Machine,
Cutting or Breaking Machine,
Hackling Machines,
Spread Boards,
Drawing and Doubling Frames,
Roving and Gill Spinning Machines,
Automatic Spinning Machines,
Throstle Spinning Machines.
The yarns employed may be as small as 60’s for the finer sizes and as
thick as 18’s for the heavy or common sizes; the significance of this
yarn numbering will be explained later.
In order to have some definite purpose in view, let it be assumed that
it is necessary to make a high-class rope from Italian hemp; the fibre
to be used must, of course, be of a good quality of cordage hemp. When
the bale of hemp is opened, the fibre will be found to be in “heads” or
“stricks,” that is, collected into groups with a girth of from 8 to 12
in., and to be from 7 to 12 ft. in length and sometimes even longer.
The first operation is that known as “softening,” which makes the
fibres, as the name of the operation indicates, more supple, and hence
better adapted for undergoing the subsequent operations. Different makes
of machines are in use for softening the fibrous material, the chief
feature in each machine is that the heads or stricks of fibre are
squeezed between fluted rollers.
In one type of machine the end of the strick is passed between the first
pair of blades of an Archimedean screw, then between the fluted rollers
of which there may be three, and its end brought round and joined to the
other end of the strick; in this way an endless band of fibres is
formed. The fluted rollers act as indicated, and at the same time the
Archimedean screw gradually conveys the endless band of fibres from one
end of the screw to the other end, each slight movement causing the
fibres to enter between the fluted rollers at a different place. This
type of machine, which is, however, rather dangerous for certain classes
of workers, is considered quite efficient and satisfactory by many
spinners, but the machine which is most extensively used is known as a
“reciprocating softener,” and is made by such firms as Messrs. Reynolds
and Messrs. Combe Barbour, both of Belfast, and by Messrs. Lawson of
Leeds.
The action of the rollers of the reciprocating softener is rather
complicated, for, in addition to the usual method of rotating in one
direction for the sake of delivering the material, the rollers are moved
bodily forwards and backwards a short distance alternately. The
multiplicity of motions has for its aim that of subjecting every
particle of the strick as much as necessary to the softening action of
the flutes; the effect of these operations on the hemp is quite evident
when the stricks emerge from the delivery end, for the material is much
more pliant than when it entered, and is in such a condition that it may
be greatly refined in the subsequent operations.
In this machine the forward motion of the rollers is obtained by a
special arrangement of gearing from the pulley shaft which extends
through the machine and carries a further belt pulley at the other end.
A belt from the latter pulley drives by means of another pulley an upper
shaft, while a further belt connection from a pulley on this upper shaft
conveys motion to a pulley running on a stud projecting from the main
frame. Compounded with the latter pulley is the speed change pinion, and
a train of gearing, consisting of four pairs of compound wheels, conveys
the desired motion to the fourteen pairs of fluted rollers which are
arranged in two concentric semicircles in the upper part of the machine.
The centre of these concentric semicircles is the central shaft of the
machine, and on this shaft is placed the pinion and wheel of the second
compound. Near the ends of this central shaft, and close to the outer
part of the two main frames, swings two substantially-constructed
brackets; each bracket has two horizontal arms from each of which a
short shaft projects to carry a wheel and pinion, while the extreme
lower end of the bracket is attached by means of a connecting rod to a
crank placed on the large wheel below, and driven from, the main pulley
shaft.
As indicated, this mechanism is duplicated, one set on each side of the
machine. The object of the small pinions on the horizontal arms of the
swinging brackets is to drive the fourteen pairs of fluted rollers
through the medium of two large wheels, one on each side, each wheel
being provided with internal teeth. The object of the cranks and
connecting arms to the said brackets is to cause the fourteen pairs of
rollers to reciprocate. This reciprocation adds to the effective
softening of the stricks by rotating the material for a longer time in
the machine, and thus repeating the softening effect of the rollers on
different parts of the fibrous material.
After the stricks have been efficiently softened in one or other of the
machines mentioned, they are conveyed to the cutting or breaking machine
which is adapted to sever the stricks into lengths suitable for
treatment in the hackling machine.
[Illustration: _By permission of Messrs David Bridge & Co., Ltd._
FIG. 18
BREAKING MACHINE]
These cutting or breaking machines are of two distinct types--
(_a_) Those in which the fibres of the stricks are torn asunder; and
(_b_) Those in which the fibres are broken by the action of what are
known as “cutting wheels.”
A good example of a machine which tears or breaks the stricks is that
illustrated in Fig. 18, and made by Messrs. David Bridge & Co., Ltd.,
Castleton, Manchester. The machine is of substantial construction, but
experienced operatives are required to take charge of it. One end of the
softened strick is wrapped round the back fixed square bar to the left
of the illustration; then about two turns of the strick are wrapped
round the front square bar which rotates when the attendant presses down
the foot lever near the floor. Since the revolving bar has a tendency to
carry the strick round with it in virtue of the movement given to it by
the train of wheels from the motive part, it follows that ultimately the
stretch of fibres between the two square bars will be broken, and then
the operation is repeated with the remainder of the long strick. The
friction clutch, on the right of the three pulleys, and the main shaft
are revolving continuously while the belt on the middle pulley is in
motion, but the friction pulley itself moves only when the friction
clutch is expanded due to the downward movement of the foot lever which,
at the same time, releases the brake on the left pulley of the three.
When the foot is removed from the foot lever or treadle, the clutch fork
slides the clutch on the shaft and breaks the contact between the
friction clutch and friction wheel; simultaneously the brake grips its
pulley and thus arrests the wheels and the rotating square bar.
The cutting or breaking type is designed on quite different lines from
the above machine, and a very popular and efficient machine of the
former type is known as the “Revolving Cutting Machine.” A series of
round pins (sometimes V-shaped teeth) project from the face or periphery
of a large central revolving wheel, and on each side of this wheel, and
at a suitable distance from it, is a pair of slowly-moving rollers which
are grooved on their circumferences to intersect with each other and so
grip or hold the material as it is being fed to the pins of the cutting
wheel. The operative cutter stands in front of the machine with a long
strick of hemp in his hands. He grips the strick at two convenient
places, and, having decided upon the point where the piece should be cut
or broken, he arranges for this point to pass into the machine midway
between the two pairs of feed or retaining wheels. The machine is made
in duplicate so that the same cutting, or breaking wheel may serve for
both, but each operative has, naturally, his own set of feed wheels.
As already stated, the lengths of the pieces when broken or cut will
depend upon the type of hackling machine in which the severed lengths
are next to be treated, and also upon the particular class of rope into
which the fibres are to be spun. The usual length limits are 24 in. and
30 in., although conditions might arise in which it is desirable to go
beyond the extremes of these common lengths.
The suitable lengths of cut material are now made up into convenient
sizes or bunches and conveyed to the machine hackling department.
Certain classes of Russian, French, Chinese, Indian and Italian hemps
may be considered in common in all subsequent operations, and, in
general, will require most of the treatment which is given to the
specific case of Italian hemp under discussion.
[Illustration: _By permission of the Edinburgh Roperie Co._
FIG. 19
HACKLING MACHINE]
The hackling machines which are used in modern cordage or rope walks are
similar to that reproduced in Fig. 19. In this particular machine there
are sixteen different holders with pieces of hemp fibre depending from
each, the lowest visible part of the fibre being on the same level as
the uppermost part of the hackles or tools. The visible parts of the
latter extend to a point in line with the waist of the attendant. There
are four sections of tools in the full width, and each section is made
up of four sets, while each set contains twenty-four tools, the whole
arranged in a closed path so that while they rotate, the pins in the
tools may act upon the pieces of hemp as the latter move in a vertical
plane under the influence of what is termed the “head” of the machine.
The number of tools vary according to the accommodation available in the
department devoted to this section of the work. The tools are fixed to a
series of bars which in turn are riveted to a set of leather sheets, the
whole being rotated as indicated by means of carriers which are arranged
on two shafts with suitable fixings.
In the “head” the necessary mechanical parts are placed for moving the
holders, and therefore the pieces of hemp, collectively and
intermittently along what is known as the “channel.” The inclined rod,
immediately under the name plate of the machine, with its additional
parts convey this motion to each of the holders. In this manner, each
holder, with its complement of hemp, is moved in regular succession
opposite each of the sixteen sets of hackles or tools, and therefore
passes from one end of the machine to the other. This movement takes
place when the hemp is at or near its highest point. As each holder
reaches the end of the machine, it is removed from the channel, the bolt
of the holder unscrewed, the plate removed, and the piece of hemp turned
end for end. After this the plate is again placed in position, the nuts
screwed tight, and the holder entered into a similar channel on the
other side of the machine, but with the undressed end of hemp downwards.
A very similar movement is now imparted to the holders at this side of
the machine so that the same process of hackling as that performed
already may be imparted by an identical group of tools. The work is, of
course, continuous in this respect that the girl or boy is almost
constantly engaged with the attention of the holders as they reach the
end in regular short periods of ten to fifteen seconds. The hemp
ultimately reaches the end of the machine from which it started, but in
a different plane, and is withdrawn from the holder to be replaced by an
undressed piece.
Until a comparatively short time ago all the above operations of feeding
were done by hand as explained, but most modern hackling machines have
now attached automatic mechanism for performing these functions. The
machine in Fig. 19 is provided with this automatic screwing and
unscrewing mechanism. One attendant introduces the pieces of hemp
between the plates of the holder when such plates have been separated by
the apparatus, but from this point all the operations, including the
removal of the holder, the turning of the piece of hemp, the unscrewing
and screwing of the nuts, and the insertion of the holder with the
unhackled ends downwards into the second channel, are performed by this
ingenious group of automatic machinery. The design of such machinery
differs with different machine makers, but very similar principles are
embodied in all. The ends of the hackling machine frame are in all cases
substantially made so that all parts may give the minimum amount of
trouble in actual work.
The size of the pieces which are held by the holder and acted upon by
the tools during the operation of hackling will depend upon the class of
yarn to which the fibre has to be spun. As a general rule, the pieces
for rope and twine yarns are arranged so that there are two to four per
pound; in other words, the pieces are from ¼ lb. to ½ lb. each. It must
be remembered that the finer the quality of yarn desired, the more
hackling must take place, and hence it will be necessary to use a
hackling machine with finer tools, and also to employ more tools in a
row.
As a general rule the best yield of fibre is obtained when the maximum
number of tools are used, but at the same time it is necessary that the
grading of the pins or hackles in such tools should be judiciously
chosen in order that the splitting or cutting should be gradual, and
thus exercise a less violent action on the fibre than would obtain with
an indifferent grading.
In addition to the grading of the pins, advantage may also be taken of
what is known as the “grouping,” that is, the order in which the pins
are arranged on the tools. The grouping is of the greatest value in the
coarser-pitched tools, and although some hackling experts prefer to have
the pins in two rows on the finest tools, the Authors consider that when
all the pins in the finer tools are in one row, the work is done better
for the line, and the tow produced is of good quality, while such an
arrangement offers the best and most economical facilities for keeping
the tools in good condition. A good arrangement of grading and grouping
on ten tools may give a greater variation in the splitting or cutting
than would result from an indifferent arrangement of grading and
grouping on a larger number of tools.
Three different arrangements of grading appear below--
Number of pins per inch width of tool
───────────────────────────────────────────────────
¼ ½ ¾ 1 1½ 2 4 6 8 10 = 10 tools
⅛ ¼ ⅓ ½ ⅔ 1 1½ 2 3 4 5 6 8 10 = 14 „
⅛ ⅙ ¼ ⅓ ½ ⅔ 1 1½ 2 3 4 5 6 7 8 10 = 16 „
All modern hackling machines should be arranged to give the best
possible yield of line, and also of tow, from the material which is in
process, since by this effort an increase in the relative value of the
finished article is obtained, and a highly-valued product secured at a
comparatively low cost of manufacture.
As the pieces of hackled hemp are delivered from the hackling machine,
they are made up into suitably-sized bundles and conveyed to the line
store.
A record of all the materials in the various stages of manufacture is
kept in the books of the respective departments, and such records can
quickly be referred to at any time by those who are responsible for the
production of the various classes of goods which are being made.
As already indicated, certain classes of hemp may be so clean when
purchased, that they can be used for some types of cordage yarns without
any preliminary hackling, and goods made in this way may compete
favourably with those made by processes which include hackling. The
object aimed at in these cases is usually one of price and not exactly
of quality, for when the latter is the predominating condition, the
superior value is attached to the yarns made from hackled fibre.
Nevertheless, when it is simply a question of equivalent suitability for
specific purposes, and when approximate values are obtainable by the two
methods of manufacture, the conditions offer a choice which is of
extreme importance at those times when the available suitable fibre for
either method is scarce, or when either is very abundant.
Although the above choice presents itself for the cases mentioned, it
will be understood that for the better grades of cordage one must employ
either a very high grade of cleaned hemp, or a grade of hemp which has
been hackled and cleaned by hand or by suitable kinds of machines.
In very special cases, _e.g._, high-class threads and cord yarns, where
great strength and uniformity are desired, it has been found advisable
to prepare the fibre entirely by a system of “hand dressing.” The hand
method lends itself naturally to more careful selective treatment. It
should, however, be stated that it is not usual to adopt this method
except for the production of a comparatively small quantity of fine
yarns, that is, thin yarns. Sewing twines and cords should be level and
strong, but not necessarily fine, unless for the finest class of work
into which these threads are to be introduced, as, for example, in the
glove industry in which case the fibre used is often flax. These finer
grades of threads and twines, as well as the finer classes of cordage,
may require the whole range of operations to produce the finest and
cleanest product consistent with the work for which it is intended to be
used, although, as stated, the hand hackling may be employed for the
flax intended for use in the manufacture of fine thin yarns, whereas, it
is preferable to employ machine hackling for the equally valuable but
thicker yarns. From this stage, however, the operations for the
continuation of the processes of manufacture from the two distinct types
of dressed line are conducted mechanically.
In perhaps the most extensive scheme of hackling there is a combination
of hand and machine work. The first operation is termed “Roughing,” and
consists of drawing the pieces of hemp or flax through a set of hackle
pins arranged or grouped in a wooden block, and termed a “Rougher’s
Tool.” This operation, when correctly performed, leaves the fibres
practically parallel, their ends approximately in line with each other,
and separates these long fibres from the shorter ones which are left
amongst the hackle pins, and which are removed regularly to be
ultimately used as “tow” in what is known as the “carding” process.
These long, partially-combed and split fibres are now taken to the
hackling machine to undergo a further treatment of combing and splitting
as already briefly described. Finally, when the pieces leave the
hackling machine they have to undergo for a second time a hand process
of hackling which is termed “Sorting and Selecting,” after which the
material is made up into a bundle.
It is obvious that such an extensive scheme of hackling is not only slow
but also costly, and is attempted only for the most valuable raw
materials to be used for costly finished goods such as fishing lines,
fine cords, and for valuable threads which are used in the glove,
leather and cognate industries.
It will thus be seen that there are in reality three distinct methods of
preparing the fibres into the product known as “line,” and the finished
product thus obtained then passes through a series of machines, termed a
“system,” in which the fibres are first arranged in such a way as to
form a continuous thin and broad ribbon termed a “sliver,” then into a
more or less circular and slightly-twisted form termed a “rove,” and
ultimately into a much finer circular and twisted form termed a “yarn”
or “single thread.” Rope and heavy cordage yarns are often made by a
simpler process than that just enumerated. The operations which these
yarns or single threads subsequently undergo will be discussed at the
proper place. In the meantime we purpose mentioning the different
machines, and then briefly to describe and illustrate these machines
which jointly form what we have called a “system.”
────────────────────┬────────────────────┬───────────────────────
System I for Fine │ System II for │ System III for Common
Classes of Line │ Heavier Line │ Yarns from Tow.
Yarn. │ Yarns. │
────────────────────┼────────────────────┼───────────────────────
Spread Board │ Spread Board │ Carding Machine
│ │
Sett Frame │ Sett Frame │ Drawing Frames
│ │
Drawing Frame │ Finishing Drawing │ Roving Frame
│ Frame │
│ │
Roving and Gill │ Automatic Spinning │ Dry Spinning or
Spinning │ │ Automatic Spinning
│ │
Dry Spinning │ │
────────────────────┴────────────────────┴───────────────────────
The machine known as the “spread-board” is so called because the
function which it performs is the mechanical sequel to the manual
operation which was conducted somewhat as follows: A board about 9 ft.
long was covered with an even layer of the pieces of hackled flax or
hemp so arranged that each succeeding piece partially overlapped the one
immediately before it much in the same way, so far as overlapping is
concerned, as obtains with the scales of a fish or the parts of a fir
cone. One operative would place his hands on the material thus arranged,
while another operative would draw forward the material, reducing it in
girth but increasing it in length, by causing some of the fibres, and
all of them in turn, to slide a distance on their neighbouring fibres.
At the same time the drawn-out material would be kept as uniform as
possible in thickness, and the operation would be continued until the
thin drawn-out length was probably five to ten times the length of the
more bulky material which was originally laid as explained on the board.
The modern technical term for this elongation or attenuation of groups
of fibres is “drafting,” and the dual operation described above is now
performed in the modern spread-board, the delivery end of one of which
is illustrated in Fig. 20.
[Illustration: FIG. 20
SPREAD BOARD]
The use of the spread-board is rendered necessary because the pieces of
material from the hackling machine are made up of individual and
comparatively short lengths of fibre, and the essential object for the
satisfactory continuation of the processes of manufacture is to convert
these short lengths into a continuous length termed a “sliver.”
The pieces of hemp or the like are first weighed in a balance near the
feed end of the machine, and are then arranged by hand on narrow endless
travelling belts, termed “spread leathers,” so that the thin end of one
piece of hemp is overlapped by the thick end of the next piece and so
on. These “spread leathers” form the moving bases of narrow channels,
the sides of which keep the pieces of hemp in their own channel. But
instead of only one row of moving fibres or pieces as in the primitive
process, there may be four or six of the above-mentioned channels.
The neatly-arranged pieces in each channel are carried forward slowly
but continuously, each group by its own endless belt, until all the
groups reach the first pair of rollers called the back or retaining
rollers. After the pieces leave these rollers they are penetrated by a
large number of pins or hackles arranged on what are known as “gills” or
“fallers.” There may be four or six gills on each faller, and the
fallers rise in turn to cause the pins to enter the narrow sheets of
fibres, to join the faller which immediately preceded it, and to move
along with the majority of the fallers in a body towards the drawing
rollers. In the spread-board illustrated in Fig. 20 there are four
channels, and therefore four pressing rollers in contact with the
drawing roller which extends the full width of the machine; all the four
pressing rollers are distinctly shown near the upper part of the
illustration.
It will be understood that the four narrow sheets of fibres will
ultimately reach the drawing and pressing rollers, and since the surface
speed of these rollers is much greater than that of the back or
retaining rollers, the fibres which are clear of the grip of the
retaining rollers will slide on those whose movements are restrained by
the rollers and gill pins, and since there is always a quantity thus
liberated, the draft is accomplished according to the relative speeds of
the two sets of rollers. The effective contact between the rollers for
drafting is obtained by means of levers two of which are shown near the
floor and to the right of the sliver can in Fig. 20.
The gills or fallers are moved forward by spirals or screws and at
practically the same surface speed as the “spread leathers” and the
retaining rollers; as each faller reaches its full forward position, it
is caused to move downward and then backward in a lower plane, and
ultimately to rise again to enable the pins to enter into a fresh
portion of the sheet of fibres; after this cycle is completed, the same
functions are repeated while the machine remains in motion.
The four slivers which leave the drawing and pressing rollers unite into
two pairs through the medium of doubling plates; one pair of slivers
thus united is guided to a conductor, and then passes between the
delivery rollers and into a sliver can shown in the foreground of Fig.
20, while the other pair, part only of which appears in the
illustration, follows a similar course into a neighbouring sliver can.
The extent to which the fibres are drawn out in the spread-board, that
is, the draft of the material, varies from about ten to twenty.
The gradual tendency to call into action mechanical parts to perform
work which was originally done by hand is further emphasized in the
latest attempt to feed the above-mentioned short pieces of hemp or the
like automatically from the hackling machine to the spread-board. This
ingenious device, the invention of Mr. Joshua Eves, of Belfast, carries
the hackled pieces from the holders of the hackling machine and lays
them on the “spread leather” in the channel, and, in addition, it is
provided with a regulating device to preserve as near as possible
uniformity in the thickness of the resulting sliver which, as usual, is
delivered into sliver cans as already described.
Even with the greatest care, the most efficient type of machine and the
finest stage of hackled fibre, it is practically impossible to achieve
an absolutely uniform sliver. In order, therefore, to approach a
practicable ideal sliver, it is usual to resort to a process of
“doubling” and a further operation of drawing; indeed, the next machine
to which the slivers pass is termed a “drawing frame.” Before dealing
with this machine, however, it is desirable to discuss another distinct
method of forming the initial sliver from fibrous material.
In general, the sliver prepared by the spread-board is intended for the
production of level and high quality yarns, but it is evident that,
during the operations of scutching and hackling, a certain quantity of
the shorter fibres will become detached from the main body of the
strick. These shorter fibres, termed tow, are not only weaker than the
line fibres but are also accompanied by impurities which must be removed
in the subsequent operations; they are graded according to quality, and
ultimately treated by a distinct method which, however, prepares them
into a sliver very similar to that which emerges from the delivery
rollers of the above-described spread-board. Then, as already mentioned,
the after processes for both types of sliver are practically identical.
The conversion of this tow into a sliver takes place in what is known as
a “carding” machine. This is a particular construction of a general type
of machine which is used for the same purpose in most textile trades
where comparatively short fibres have to be converted into sliver form.
The function which the card--a contraction for carding machine--performs
is to split up the fibres and to lay them parallel with their
neighbours; for this purpose the machine is provided with a series of
rollers which are covered or clothed with sharp pointed pins, the size,
direction and inclination of which depend upon the particular work which
each set has to perform. A set of cards comprises two or more machines
each of which differs slightly from the others, and invariably arranged
so that succeeding machines in a set are provided with finer clothing,
_i.e._, smaller and shorter pins and more closely set. The simplest set
is where two machines are involved, the first one termed a “Breaker
Card,” and the second one termed a “Finisher Card.” In both machines a
series of comparatively small rollers, say from 8 to 20 in. diameter,
and covered with pins, are arranged partially round and close to a large
central roller of 4 to 5 ft. diameter, also covered with pins and termed
a cylinder. The general appearance of the machines will be gathered from
the two rows in Fig. 21; the nearest machine on the left shows the
delivery side of a breaker card where the sliver is delivered into a
can; the nearest machine on the right illustrates both feed and delivery
sides of a finisher card.
[Illustration: FIG. 21
BREAKER AND FINISHER CARDS]
The tow, which has been previously softened, is laid as evenly as
possible on a travelling endless sheet by means of which the fibrous
material is carried to the pins of the “feed roller” which rotates very
slowly and at the same surface speed as the feed sheet. Immediately the
material emerges from the feed rollers, or feed roller and “shell,” it
is acted upon by a series of hackle pins projecting from the periphery
of the cylinder, and moving at a surface speed of more than 2,000 ft.
per minute. The fibres are therefore combed and carried off the pins of
the feed roller by the pins of the cylinder to a series of rollers
arranged in pairs, each pair consisting of a “worker” and a “stripper.”
When the fibres on the pins of the cylinder reach the first pair of
worker and stripper, the bulk of the material is carded and ultimately
returned to the pins of the cylinder to be carried to the next pair of
rollers, and so on, until it has been sufficiently equalized and cleaned
for the particular yarn into which it is to be made.
By this time the uneven fibres have been considerably reduced in
thickness, and have indeed been converted into a thin wide film or sheet
of fibrous material, and in this state it is removed from the pins of
the cylinder by the pins of a “doffing roller” or “doffer.” The thin,
broad film of fibres now enters between a pair of drawing rollers--seen
near the top of the machine on the left in Fig. 21--and into the upper
and wide part of an almost vertical tin conductor. The width of this
conductor decreases from the upper to the lower end, and ultimately its
width is contracted to about 3 in. where the contracted sheet, now much
thicker and about 3 in. wide, is in the well-known form of a sliver. The
sliver emerges from the mouth of the conductor, enters between the
delivery rollers and ultimately drops into a sliver can in a very
similar manner to that depicted in Fig. 20.
About ten or twelve of these sliver cans from the breaker card are now
transferred across the space, termed a “pass,” to the feed of the
finisher card on the right of Fig. 21. These ten or twelve slivers are
fed into this machine and they undergo a further and similar treatment
with from four to six pairs of rollers, and finally the finished and
single sliver is delivered into a can near the side of the machine. In
both machines the material is drafted according to requirements.[1]
We have thus arrived by two several ways at the production of a
continuous sliver. Both types of sliver pass next to what is known as a
“Drawing Frame,” or rather to a set of drawing frames, usually termed,
first drawing, second drawing, third drawing, and so on, if more than
three are employed.
The machines used for the two kinds of slivers are practically identical
in principle and construction, the only difference being that provision
is made to suit the lengths of fibres of which the respective slivers
are formed; in technical phraseology the “reach” for the line sliver is
longer than the “reach” for the tow sliver and is, approximately,
proportional to the maximum length of fibres which compose the two types
of sliver.
It will be understood that, in general, the ultimate aim is the
production of a thread of some kind, the sectional area of which is less
than that of the sliver which is produced either at the spread-board or
the finisher card. And it will be obvious that if we unite two or more
slivers at the feed side of the “Drawing Frame” we increase the
thickness or volume proportionately; hence, if the sliver which is
delivered from the drawing frame is required to be smaller in volume
than any of the single slivers which enter the machine, and this is
generally the case, although not universally so, the process of drawing
out the fibres, or drafting, must be continued. In the first drawing
frame uniformity is chiefly the object, and it may happen that in the
combined processes of doubling and drafting it may be convenient to
produce in this frame a sliver of greater volume than the individual
slivers at the feed. In such cases, most of the drafting would take
place in the succeeding drawing frames.
The first drawing frame is often termed a “Sett Frame,” and sometimes a
“Doubling Frame.” The first-named of the three owes its designation to
the process of attenuation or drafting, the second to the number of
slivers which in the process are employed to form one sliver, and the
third to the particular case where two slivers only are united. Although
the exact meaning of doubling is the combination of two slivers, the
same word is used however many slivers are combined in one group.
The drawing frame has a great resemblance to the spread-board, so far as
the principles of the operations are concerned; it differs from it in
the fact that whereas the latter is fed by short detached lengths, the
former is fed by continuous slivers.
The length of sliver which is delivered from the spread-board is
measured; this is accomplished by the size of one of the drawing rollers
and the necessary subsequent mechanism; these jointly cause a bell to
ring, or to move a hand over the face of a clock. The length thus
indicated is called the “bell or clock length,” and whichever system is
adopted, the operative receives a certain weight of material which must
be fed into the machine between two consecutive ringings of the bell, or
during the time that the clock hand makes one complete revolution.
The cans are weighed as they are filled and the net weight of the sliver
marked on. After a sufficient number of cans have been filled, say
eight, averaging 20 lb. each, or 160 lb. in all, and the length of
sliver in each can, say 250 yd., eight cans are placed at the feed side
of the drawing frame. The average weight of the combined slivers on
entering the drawing frame is, therefore--
160 lb. × 16 oz. per lb.
──────────────────────── = approximately 10 oz. per yd.
250 yd. length
If the draft is, say 12, the 160 lb. of material when delivered in the
form of a single sliver will be--
250 yards × 12 draft = 3,000 yd.
Then--
160 lb. × 16 oz. per lb.
──────────────────────── = 0·85 of an ounce per yd.
3,000 yd. of sliver
The operation of drawing is conducted as in the spread-board by means of
retaining or back rollers, gills, drawing and pressing rollers. It
should be again pointed out that the distance between the retaining
rollers and the drawing rollers--termed the “reach”--should be regulated
by the length of the fibres under treatment, and should be greater than
the longest individual fibres, otherwise such fibres, instead of sliding
on those already held, would obviously be broken because the surface
speed of the drawing rollers is much greater than that of the retaining
rollers; in the case under notice the ratio is 12 to 1.
The best scheme yet devised for filling up this intervening space
between the two pairs of rollers, and of providing support for the
moving fibres is that of the above-mentioned gills. The use of gills in
the machine is of great importance, for on the correct adaptation of the
gills to the material in process depends the degree of efficiency of the
machine.
As the gills move from the retaining rollers towards the drawing rollers
in virtue of the action of suitable spiral or other mechanism, each
group forms a compact sheet or field of hackle pins, and this field of
pins regulates and restrains the movements of the fibres to the
requisite extent as the latter move amongst them due to the pulling
action of the drawing rollers.
In this way each individual sliver in its own set of pins is reduced in
size, and any local defect in a sliver is calculated to be overshadowed
or eliminated when the said sliver joins the remainder of the slivers at
the “doubling plates” which are situated between the drawing and the
delivery rollers. The result is, therefore, a single sliver of greater
uniformity than any of the constituent slivers, such sliver being
smaller, equal to, or greater than, any of the individual slivers from
which it has been made according to the ratio of the doublings and
draft.
A series of drawing frames in system as illustrated in Fig. 22, will
provide the necessary doubling and drafting, and so reduce the sliver to
a suitable size for use in any of the following yarn-forming or spinning
machines--
(_a_) The Roving Frame which would be used to convert the sliver into a
somewhat circular form, and simultaneously to wind this twisted sliver
on to a large two-ended bobbin ready for the spinning frame (dry
spinning).
(_b_) The Gill Spinning Frame which is a machine by means of which very
high-class yarns can be produced with a perfect system of drafting and
twisting in one operation.
(_c_) The Automatic Spinning Frame in which the heaviest class of
cordage yarn is spun by the simplest and most direct method.
[Illustration: FIG. 22
DRAWING FRAMES]
The roving frame is one of the most complicated groups of mechanism and
one of the most perfect machines which is used in the whole system. Its
function is of a multiple type, for the mechanism of the machine not
only necessitates the use of retaining rollers, gills and drawing
rollers to effect a draft, but after the reduced sliver has been passed
through the delivery rollers, it introduces a certain amount of twist to
the sliver--incidentally making it somewhat circular in section--and
finally winds the twisted sliver, termed “rove,” on to a large bobbin.
The method of drafting has already been briefly described, hence, no
recapitulation is necessary. The essential amount of twist for each
individual sliver is imparted by its own spindle, an upright rod which
rotates rapidly, and upon which the large bobbin runs or rotates
loosely, while attached to the top of the spindle is a “flyer”
resembling an elongated inverted U, thus: ⋂. Most of these parts are
clearly seen in Fig. 23, which represents, of course, the delivery side
of the machine. At the other side of the machine, the feed side, there
is a sliver can with its sliver for each thread and bobbin, the bobbins
being arranged in two rows upon discs in corresponding holes in the long
shelf, termed the “lifting rail,” the “builder rail,” or simply the
“builder.”
[Illustration: FIG. 23
ROVING FRAME]
The extreme ends of the two legs of the flyer are bent to form or carry
eyes, and into one of these eyes the twisted sliver is passed, while
between this eye and the delivery rollers the sliver is centralized by
passing it through a guide eye. The function of the eye in the flyer is
that of guiding or winding the rove on to the bobbin, and this is made
possible because the bobbin itself is made to rise and fall between the
legs of the flyer through a distance equal to the length of the
bobbin--hence the necessity for the long legs of the flyer or inverted
U.
The spindles and bobbins are driven independently and positively by
wheel gearing, and it is obvious that the rove must be wound on to the
bobbin at the same rate as it is produced. Since the speed of the
drawing and delivery rollers is constant, the delivery of the sliver is
constant, and so is the production of rove, although the length of rove
delivered is infinitesimally less than that of the sliver in virtue of
the small contraction which takes place during the twisting. If the
diameter of the rove on the bobbin always remained the same size, which
is obviously impossible, the revolutions of the bobbin would be
constant. But every layer of rove which is wound on to the bobbin by the
joint action of the rotating spindle, the rotating bobbin, and the
vertical movement of the bobbin on the builder, adds for each vertical
movement, up or down, one more layer of rove to the partially-filled or
empty bobbin, and thus increases the diameter of the combined bobbin and
rove. Hence it is necessary to impart what may be termed an intermittent
and variable motion to the bobbin; this is done by an exceptionally
unique and intricate group of mechanical parts termed the “differential
motion.” The function of the differential motion is to alter the speed
of the bobbin after each complete layer of rove has been wound on to it,
because it will be clear that when the direction of the builder is
changed, the winding of the rove is performed on a diameter which is
greater than the last by approximately twice the diameter of the rove.
The discs upon which the bobbins rest are provided with two vertical
pins which enter two of the holes in the flange of the bobbin, seen
clearly in the empty bobbins near the frame, and by means of which the
bobbins are driven at the desired speed. Accurate adjustment of the
parts is necessary, and a lengthy description with numerous line
drawings are essential to a clear understanding of this ingenious
mechanism.[2]
SPINNING.--The bobbins filled with rove yarn, as illustrated in Fig. 23,
are ready to be removed or “doffed,” as the operation is technically
called, preparatory to being taken to some type of spinning frame where
a further extension or “draft” of the yarn takes place, and
simultaneously the finished product of the desired thickness or “count”
is wound upon a much smaller two-ended bobbin.
A large-used type of dry spinning frame is illustrated in Fig. 24, and
this type of machine is usually employed for spinning yarns the “counts”
or “sizes” of which are represented by the numerals 3 to 16. Yarns which
happen to be of lower or higher count than these limits are produced on
other similar or different type of machine.
In Fig. 24 the large rove bobbins are seen distinctly on projecting
pins--termed a creel--at the top of the machine. Each rove from its
bobbin, which can rotate freely on its peg, is passed between retaining
rollers, and over what is known as a “breast-plate,” through the
contracted groove of a “tin conductor,” between a pair of drawing
rollers, through a slot in the “thread-plate,” through an eye in one of
the legs of the flyer, and ultimately on to the bobbin which rotates on
a spindle upon the upper end of which the flyer is fixed. In
“long-reach” machines it may be necessary to use additional rods or
binders which act as auxiliary breast-plates.
[Illustration: _By permission of the Edinburgh Roperie Co._
FIG. 24
DRY SPINNING FRAME]
All the spindles on one side of the frame are individually driven by
flat tapes or round bands from a driving tin cylinder situated near the
floor and inside the frame as shown in Fig. 24, and driven direct from
the main pulley. The flat tape or band passes partially round this
cylinder, and then partially around a “whorl” or bobbin-shaped pulley of
about 1½ to 3 in. diameter on the spindle; these whorls and tapes are
seen clearly on the first three spindles in the illustration, and in the
same line as the “temper weights.” The latter hang from cords attached
to the back of the “builder” which imparts the up and down motion to the
bobbins during the operation of spinning, and so enables the yarns to be
distributed over the full length of the bobbin. The cord which is
attached to the temper weight is caused to bear on the grooved flange of
the bobbin, and by moving the cord into successive grooves or notches in
front of the builder as the bobbin fills, a greater part of the groove
is acted upon by the cord and weight, and thus the drag is increased.
Demi-sec spinning, as the name implies, refers to a process between dry
spinning and wet spinning. In the demi-sec frames a slight quantity of
water is added to the drawn-out and partially-twisted threads as the
latter pass from the drawing rollers to the flyers. The purpose of this
moisture is to smooth and lay the hairs of fibre which would otherwise
project from the main body of the yarn as in the case of dry-spun yarns.
It is usual to apply this method of spinning to thread yarns.
The draft necessary for converting the rove to the desired size or count
of yarn is regulated by changing the value of the gearing, the wheels of
which are enclosed in the oval covering at the end of the view in Fig.
24; near this covering is also seen the heart-shaped cam, lever and rod
which are used for operating the builder.
GILL SPINNING.--In the ordinary spinning frame the material supplied is
from rove bobbins, but in the gill spinning machine, the material is
supplied as a sliver from a sliver can, one for each spindle. The gill
spinner has a drawing head similar to that in a roving frame, and the
spindles and flyers are usually driven by bands. The machine used for
gill spinning might be compared with a roving frame with or without the
winding motion or differential gear.
[1] For an exhaustive description of Carding see the Authors’ work on
_Jute and Jute Spinning: Part I_.
[2] Readers who are sufficiently interested in this and several other
machines which are briefly described in this work, might consult the
following works of the Authors, which are at present appearing
serially, and which will be published in book form when completed:
“_Jute and Jute Spinning_”: _The Textile Manufacturer_; “_Flax and
Flax Spinning_”: _The Textile Recorder_.