THE OPENING MACHINE.
(39) Mixing being completed, the cotton is treated by machines
specially designed to remove the impurities which are always mixed with
it as received from the shipper. These impurities include sand, dirt,
broken seed, and leaf. In addition to these there is a certain quantity
of “nep” which is caused, as previously described, by the matting
together of short, unripe, or immature fibres. To eliminate the whole
of these substances, two sets of machines are required; the first being
responsible for the removal of the heavier foreign bodies, such as sand
and dirt, and the second for that of leaf, nep, and short fibres.
(40) Of the machines in the first division the opening machine, or
more briefly the “opener,” is the first. Its _raison d’être_ is found
in the matted condition of the cotton as taken from the bale, and the
less open it is when taken from the stack, the greater the work of
the machine. As the name indicates, the object of the latter is to
disentangle the fibres, but it is also designed to remove many of the
impurities held by the cotton. This twofold aim is the one with which
all the series of cleaning machines are constructed.
(41) The method invariably pursued in opening is to beat the cotton
by subjecting it to the blows of arms revolving with considerable
velocity. It may aid in the understanding of the process, if a few
words are said as to the primitive method of cleaning. Formerly the
material was laid upon grids in small quantities, and was submitted
to repeated light blows of rods or sticks delivered manually. In
this way the mass was gradually beaten into a fleecy condition, and
the dirt held by it dropped through the interstices of the grid. In
some respects, this treatment has never been equalled, but it is, of
necessity, very slow, and could not be commercially employed at the
present day. At the same time, it affords a clear indication of the
needs of the case, and is a guide to the proper treatment.
(42) In dealing with the fibre by revolving beaters of any kind, two
things are essential to success. First, the blow given must be of such
a character that the fibres are completely separated, while any rupture
or breakage of them is avoided. Second, the surface against which the
cotton is flung after being struck by the beater, must be arranged to
permit of the free passage of all impurities, while, at the same time,
so arresting the movement of the tufts or pieces of cotton as to shake
out the extraneous substances.
(43) The direction in which the cotton enters the machine, the
diameter, construction, and shape of the beater arm, and the speed of
the beater, are three of the essential features of a machine of this
kind. The successful removal of the impurities depends on the rate of
the feed—that is, the amount of material passed into the machine in a
given time—the shape of the projections on the casing surrounding the
beater, and the distance of these from each other; in other words,
their pitch. It is not a difficult matter to effectually cleanse the
cotton, so long as regard is not paid to the loss arising from damaged
or broken fibres, or from the amount of fibre driven out with the dirt.
It is, however, always to be remembered that it is desirable in any
process to utilise every portion of the material which is capable of
being worked up, and herein lies the chief difficulty of the subject.
In brief, the essential consideration is a commercial one, and that
machine is the best, and is used most skilfully, which effectually
opens the matted cotton and shakes out the largest body of impurities
with the least loss of fibre, either from its being driven out with
the dirt or by breakage or rupture. Economy and efficiency are the
watchwords of a good spinner, and nowhere is this combination more
desirable than in the early stages of the manufacture.
(44) There are three principal forms of machine used for the purpose
of opening—the Oldham Willow, the Porcupine, and the Crighton Opener.
The former is now employed rarely for cotton, but extensively for the
manufacture of yarn from waste. The other two are often employed, but
the Crighton type of machine is perhaps more widely used than any
other. There is another type of machine, which is also in extensive
employment, to which reference should be made, viz., a modified opener,
on the Willow model, of which a description will be given.
(45) The Willow is constructed with a revolving cylinder, about forty
inches wide and the same diameter, fixed on a shaft borne by suitable
pedestals. It is provided with several rows of blunt teeth on its
periphery. Above the cylinder a semi-circular casing is fixed, which
is provided with similar projections to those of the cylinder. Below
the latter a grating, grid, or “undercasing,” formed of a number of
parallel bars, is placed. The cotton is flung against these bars, and
the loosened dirt falls through the spaces between them, being drawn
away by an exhaust fan and delivered outside the room. It is the usual
practice to feed the machine by an endless lattice, or apron, of a
similar construction to that previously described. When the cotton
enters the machine it is struck by the teeth on the cylinder and thrown
forcibly against the projections on the casing. The blow thus given,
combined with the periodical arrest of its motion, causes the cotton to
be thoroughly opened and shaken, the dirt falling downwards and being
drawn away by the air current. As has been said, the Willow is falling
into disfavour. The cotton is subjected to too severe punishment, and
is therefore damaged. In addition to this, it is sometimes carried
round several times, and is formed into a sort of rope, which renders
its subsequent treatment more difficult. Moreover, the waste is greater
than is desirable, and, generally speaking, the use of this machine for
cotton is of doubtful utility.
(46) In Fig. 9 a longitudinal section of an opener, which in some
respects is a modified type of Willow, is illustrated. This machine is
made by Messrs. Taylor, Lang and Co., Limited. It consists of a feed
lattice =Q=, which travels in the direction of the arrow, and delivers
the cotton to the pair of feed rollers shown. These are duplicated when
no regulating apparatus is used, and are three inches in diameter. The
cotton is delivered at any desired speed by the rollers, and as it
projects from them is struck by the spikes or teeth on the cylinder
=O=, which revolves in the direction shown by the arrow. Surrounding
the cylinder is a case =P=, the inner surface of which has a number
of projecting nogs formed on it, against which the cotton is flung
with considerable force. This shakes out the dirt to a great extent,
and opens the material. After passing the casing =P= the cotton is
taken over a circular grid surrounding one side of the cylinder, and
contained in the body of the machine. This grid is formed of a number
of steel bars, between each pair of which an opening is left. Thus as
the disentangled cotton passes over it the heavy dirt falls out through
the openings into a space left for the purpose. After passing the grid
the material leaves the cylinder by the passage shown, immediately on
entering which it travels over the top of fixed grids =R=, through
which the sand and similar material can fall. After this the cotton
is either delivered into the room or is carried forward to a pair of
“cages” =S=, through which a current of air is drawn. This part of the
machine will be described in the next chapter, and it is only necessary
to say that the fleece of cotton is formed into a sheet and rolled up
as shown at =L=, into a “lap.” If the cotton is delivered loose it is
thrown on to a second lattice, by which the delivery is made. In order
to secure a regulation of the air current the louvre openings =I= are
provided. The area of the cleansing surface in this machine is great,
and 50,000lbs. of cotton can be cleaned in a week of 60 hours unless a
“lap” is formed, when the quantitity is reduced to 28,000lbs.
[Illustration: FIG. 9. J.N.]
[Illustration: FIG. 10. J.N.]
(47) In Fig. 10 is illustrated, also in longitudinal elevation, a
machine made by Messrs. Dobson and Barlow. The cotton is fed by a
lattice =L=, as in the preceding example, the course of which is
clearly shown. In this case the machine is fitted with pedal levers
=V=, these being employed to regulate the feed. This motion and its
method of action will be described at length in the next chapter. It
suffices to say that the cotton on issuing from the feed roller is
struck by teeth or projections on the surface of the cylinder =O= which
revolves from left to right. Surrounding the latter is a semi-circular
grid =K= with conical teeth, which encircles the cylinder for more than
half its circumference, through which the dirt is thrown, the cotton
being cleaned by these means. It will be noticed that in this machine
the area of the circular grid =K= is large, and that the material at
once passes upon it after it is struck by the cylinder. As soon as the
cotton leaves the surface of =K= it is carried forward over the grid
=U=, placed in a position well calculated to allow of the easy movement
of the material, and by means of which the removal of the dirt and sand
is more easily effected. The grid =U= is also made of considerable
area, so as to afford a large cleaning surface, which is a desideratum
in this class of machine. After leaving =U= the cotton is collected on
the cages =D=, and subsequently passed through the scutching machine,
which in this case is combined with the opener. As this machine is used
as a separate one, it will be better to leave its description until it
is dealt with by itself. It is only necessary to say that it will be
shown by numerous examples that the whole of the cleaning machines are
often combined in various ways, which are arranged to suit the special
circumstances of any case. These are so different that the combinations
are widely diverse.
[Illustration: FIG. 11. J.N.]
[Illustration: FIG. 12. J.N.]
(48) The Porcupine opener is so named from the employment of a cylinder
or beater consisting of a number of teeth spikes or blades. Two forms
of the beater, as made by Messrs. Lord Brothers, are shown respectively
in Figs. 11 and 12. The form shown in Fig. 11 is intended for use in
cleaning long-stapled cotton, and consists of a number of discs secured
to a central shaft. To these steel blades are bolted, which are so
shaped that they can be reversed when worn. The beater illustrated
in Fig. 12 is formed of a number of cast-iron discs, each of which is
hollowed on one side, and has a projecting flange or boss on the other.
These are turned to fit one another, and are bolted together by long
screws. They are further bound by a nut fitting on a screwed part at
one end of the shaft, by which they are pressed against a collar at
the other end. The teeth are =V= shaped and are chilled, being readily
sharpened after wear. In the event of the teeth of one of the discs
being broken, it is only necessary to remove it by breaking it up. An
additional disc can then be put on the end of the shaft, and the whole
screwed up again as at first. In this way the whole of the advantages
of a solid roller are secured, with much greater facilities for repair.
[Illustration: FIG. 13. J.N.]
(49) However the cylinder is constructed it is sustained by bearings
secured to the framing of the machine. Beneath it a grating or grid
is fixed, similar in construction to those previously described.
The bars are in all cases shaped so as to present a sharp angle to
the cotton as it is thrown forward by the cylinder. A dirt chamber
is, as usual, formed below the grid. The cotton is fed by a lattice
and feed rollers. The latter are formed in the ordinary way, with a
number of circumferential =V= grooves, crossed by a series of similar
longitudinal grooves, so as to form a large number of teeth, which
securely hold the material as it is fed. As the cylinder revolves 1,000
times per minute, the teeth strike the cotton and disentangle the
fibres, throwing them with considerable force against the grid.
(50) Although the Porcupine opener can be used separately and the
cotton discharged into the room, it is more usually employed in
connection with some other type of opener, or with a scutching machine.
Formerly it was a common practice to use this machine separately, in
which case it was fitted with two cylinders one behind the other.
Now it is mostly employed as a feeder to another machine, and the
combination gives very effective cleaning.
(51) Such an arrangement is shown in Fig. 13, which is a special one of
Messrs. Platt Bros. and Co. The lattice feed =F= is placed alongside
the mixing bins, and is provided with a large collecting roller,
behind which are a series of pedals, described in the next chapter, and
two pairs of breaker cylinders. By these the cotton is fed regularly
and broken up into small pieces, or partially opened before being
passed forward to the opener cylinder. The Porcupine feed rollers =G=
deliver the cotton, in the case illustrated, into the air tubes =D=,
and thence over a patent dust trunk =K=, where much of the dirt is
deposited, and which is afterwards described.
[Illustration: FIG. 14.]
(52) The opener, as made by Messrs. Platt Brothers and Co., Limited,
is shown in perspective in Fig. 14. The cotton enters the opener
chamber by the tube, as described, and is at once acted on by the
cylinder, which revolves horizontally. The cylinder is surrounded
by grids, against which the cotton is thrown, and through which the
dirt is ejected. The forward movement of the cotton is induced by the
exhaustion of the air, produced by means of a pair of fans, placed one
at each side of the machine and adjoining the exit orifice from the
cylinder chamber. Power of lateral adjustment is given to these fans,
so that they may be set in towards the centre of the machine to a
greater or less extent. In this way the stream of cotton, as it issues
from the cylinder, is directed on to the cages as required, and a very
even lap or sheet is thus obtained. It is obvious that the guiding
power of the air current is the right thing to rely upon, and, by the
arrangement described, ample regulation of it is obtained. A lap which
is even in thickness is absolutely essential to good work, and the
arrangement of fans in the way described ensures this being obtained.
The author recently saw the first lap made on a machine of this type in
a large Oldham spinning mill, and the regularity of the thickness and
evenness of the selvedge was very noticeable. The machine as shown in
Fig. 14 is a combined one.
(53) The Crighton Opener is a machine the distinctive feature of which
is the employment of a vertical conical beater. A sectional elevation
of the machine as made by Messrs. Crighton and Sons is shown in Fig.
15. The beater consists of a number of cast-iron discs =D= securely
keyed upon a vertical shaft, which is sustained at its lower end by a
bearing =E= in the frame =F=, and at its upper end by the bearing =A=.
On the discs are fastened steel blades, and it will be noticed that
their diameter increases from 18in. to 33in. Surrounding the beater is
a casing =B=, in which are a number of longitudinal slots, the inner
surface of the grids being in most cases made of the shape shown in
section in Fig. 16. A recent improvement by Messrs. Crighton and Sons
is shown in Figs. 17, 18, and 19.
[Illustration: FIG. 15. J.N.]
[Illustration: FIG. 17.]
(54) The cotton is fed by the tube placed at =C=, and a fan is fixed
just below the entrance of the tube into the beater chamber. The
direction in which the cotton enters and the positions of the fans
are important points of construction. The feed tube is not fixed in a
straight line, but is slightly curved so as to direct the cotton upward
as it enters the beater chamber. As it enters it comes in contact
with the serrated surface of a truncated conical dish, within which
the lowest arm =D= of the beater revolves. Immediately below this
dish a fan disc of the Schiele type is fixed in machines in which a
combination of feed table, air trunks, and opener is made. The object
of this fan is to exhaust the air in the tubes up to that point, and
draw the cotton forward until it reaches the cylinder. There is a
decided advantage in this arrangement over one in which the fan is
placed beyond the exit orifice at the top of the opener chamber. In
the latter case the air is required to draw the cotton through the
dust trunks into the opener, upwards past the cylinder, and so on to
the cages. In the machine as made by Messrs. Crighton, the fan at the
bottom of the dish is sufficient to bring the cotton to that point,
and all that is subsequently required of the fans placed beyond the
cylinder is to lift the cotton upwards during its progress through the
beater chamber. On this account a slower moving current of air can
be employed, and the fans connected with the cages can be revolved
at a less velocity. The full advantages of this arrangement will be
afterwards pointed out, but as the cotton is raised slowly while being
beaten, it is thoroughly opened and cleaned.
[Illustration: FIG. 16.]
[Illustration: FIG. 19.]
[Illustration: FIG. 18. J.N.]
(55) When the cotton enters the beater chamber it is at once struck by
the blades of the beater, which revolve at a speed of about 1,000 turns
per minute. The peripheral velocity of the blades is thus at the bottom
4,712 feet per minute, and at the top 8,639 feet. The blow thus given
disentangles the cotton and flings it against the inner surface of the
grid, thus momentarily arresting its motion. As the beater revolves,
the cotton continues to find its way upwards, and in its course is
repeatedly struck by the blades, which, as has been seen, have a
continually increasing peripheral velocity as they near the top. In
this way, as the cotton nears the exit orifice, which is placed at the
upper part of the machine frame, on the opposite side to the tube =C=,
it is thoroughly beaten into a fleecy condition, with its fibres well
disentangled.
(56) The shape of the grids surrounding the cylinder is an important
matter. In the form illustrated in Fig. 16, the projections on the
grid are triangular in shape, and have slots between each pair through
which the dirt can freely pass. It will be easily seen that the shape
of these grids is one which will only exercise a little clinging
effect upon the cotton, which, as it is impelled by the stroke of the
beating blade, will very readily roll pass the projections. As the
rapid rotation of the cylinder tends to slightly compress the air,
the latter finds an outlet if possible. This is the object of the
slots in the grid casing, and they fulfil it very well. But there is
always a liability that along with the air and dirt—which also passes
the grids—a little fibre may escape. It is desirable to avoid “fat
droppings” as they are called, and the grid shown in Figs. 17 to 19 has
been designed for this purpose. Each of the pockets =C= Fig. 18 shown
becomes a resting place for the opened fibre, and as its lower end
=C^{2}= is open, the dirt can fall freely. In order that the air can
easily get away, between each pair of pockets a small slot is formed,
and in this way there is no downward impulse given to the cotton while
held in the pocket. Thus each blow given to the material opens it,
drives it into the pockets where it dwells for a short time, and from
which after the passage of the beater blade =A=, it is drawn by the
suction of the air. By this system there are given short periods of
rest, which very materially facilitate the fall of the dirt.
(57) Instead of feeding the opener manually as shown in Fig. 15,
a lattice feed can be adopted. Among the many important points in
connection with the Crighton, or, as it is sometimes called, the
“exhaust” opener, none is more so than the construction and lubrication
of the footstep. This is arranged so that the foot of the beater shaft
revolves in a constant bath, either of oil or water, and great care is
taken to cover it so as to prevent the entrance of sediment or dust.
(58) In Fig. 20, a longitudinal section of the machine as made by
Messrs. Lord Bros., is given, and is accompanied by a plan of the same
machine as combined with a porcupine feed. Referring first to the
plan, the lattice feed =A= delivers the cotton to the porcupine roller
=C=, by which it is passed in a partially opened condition to the air
trunks =D=. By these it is conducted to the opening chamber =F=, being
admitted to it by flap valves =G=. The cotton enters the chamber =F= by
the tube =H=, terminating in the dish =I=. The exit orifice is placed
at the top of the chamber =F=, the course of the cotton being shown by
the arrows. The cylinder is similar to the Crighton, but the blades =E=
are fixed in malleable iron arms =L= fastened to the shaft, and can,
after wear, be reversed. Below the foot of the shaft, and within the
bearing =O=, is a loose washer =P=, which can rotate with the pressure
of the shaft, this arrangement considerably lessening the wear. At
each side of the exit of the delivery tube, fans =N= are fixed, which,
like those in the Platt machine, can be adjusted sideways for the same
object. The cotton then passes over grids =R= on to the cages =T=, from
whence it passes through the scutching beater =W= to another pair of
cages =S=, as indicated by the arrows, and is finally formed into a lap
as shown. The special construction of the beaters enables the cotton to
pass freely upwards, and prevents any stringing occurring. The speed of
the beater in this machine is 520 revolutions per minute for American
cotton, and 720 for Indian. The slower velocities used necessarily
imply the use of less power.
(59) There are one or two points to be noticed in concluding the
consideration of the Crighton type of machine. The distance from the
face of the grids to the ends of the beater blades should be carefully
arranged to suit the class of cotton treated, as, if it is too great,
the opening is not properly effected, and, if too little, the cotton is
liable to be damaged. The rate at which the feed is conducted should
always be carefully watched, because, if the material is passed in too
quickly, its bulk becomes so great in the lower part that the dirt
cannot fall freely, but is received by the entering cotton. Cleaning
is not, therefore, so effectually carried out. In addition to this, it
is desirable that the cotton should be allowed to assume a perfectly
open condition, which it would do with difficulty if the space were
overfilled. Cotton has been passed through, for a short time, at the
rate of 110,000lbs. per week of 60 hours, but for the reasons stated,
30,000lbs. is ample.
(60) It might be thought that the pitch of the projections on the
inner surface of the grid should be as small as possible, but this is
a mistake. It is essential that the cotton should strike not merely
the top or apex, but one face or side of the projection, if the full
cleaning effect is to be obtained. It is obvious that if the pitch
is too fine no such face blow would be given, and very inefficient
purification would occur. The considerations thus stated are founded on
actual experience in working the machines, and should be borne in mind
in constructing or controlling an opener of this type.
(61) It is considered by some makers to be advisable when using
this style of machine to employ one with two beaters revolving in
separate chambers, connected to each other by an air pipe. This is
more especially the case when Indian or short stapled cotton is used.
When the double machine is used, the conducting tube between the two
leaves the first chamber at the top, and enters the second at the
bottom. The driving of the opening machine is usually obtained from a
counter shaft, by which means the speed of the driving pulley becomes a
moderate one.
(62) A machine, of which large numbers have been made by Messrs. Lord
Brothers and Howard and Bullough, has a conical beater placed in a
horizontal position, and the opener proper is usually combined with a
scutching and lap machine. As this type of machine is very similar in
its general principles to that previously described, and is not now
so largely made as formerly, it is not necessary to give a detailed
description of its mechanism.
(63) It has been repeatedly stated that the various machines are united
by means of tubes, so that the cotton can readily be taken from one
machine to another. It does not matter whether the machines are in the
same room or not, or what distances separate the rooms in which they
are placed. This has been shown in Figs. 6, 7, and 8, referred to in
the preceding chapter, and the further arrangement is illustrated in
Fig. 13. In this case the cotton, after being delivered into the dust
trunk, or tube =D=, on its way to the opening cylinder, may be carried
two or three hundred yards, if desired, before it reaches the latter.
There is, of course, a limit to the distance it may be conveyed, but
it is a very wide one. There are many conveniences arising from this
procedure. It is becoming a very common practice to build the mixing
and scutching rooms away from the main body of the mill in order to
minimise the risk of fire. But even where this practice does not
obtain, the employment of air tubes is a good one, as it enables the
material to be transferred from one point to another without handling.
In this way the cost of labour is much reduced, and in addition the
cotton is less liable to damage.
(64) At one portion =K= of the conducting tube =D= an arrangement
is fitted by which a partial cleansing of the cotton occurs before
it reaches the opener. Below the level of the tube a chamber nearly
square in section is formed, as shown in section at the left-hand
corner in Fig. 20, forming the tube into a =D= shape. This chamber is
made of a length which is determined by the character of the material
used and considerations of its position, etc. At intervals of a few
inches plates are arranged so as to divide the chamber into a number
of compartments, as shown by the sectional view. Over the top of
these plates the material rolls in its forward movement, and a large
quantity of dust, sand, and heavy impurities are deposited in the
trunk. Doors are fitted to the underside of the chamber, by which the
droppings can be removed at intervals as desired. The use of these
grids has been attended with unmistakeable benefit, and leads to a much
more effective cleaning of the cotton.
[Illustration: FIG. 20. J.N.]
(65) By the method just described it is necessary to cleanse the trunks
manually at intervals, and if any neglect occurs there is some danger
of the dirt being carried forward. To obviate this, Messrs. Platt Bros.
and Co. Limited have patented and applied the arrangement shown in Fig.
21. In this case the dust chamber =L= is sustained in a manner arranged
to suit the circumstances of the case. Instead of being fitted with the
vertical plates described, an endless band is carried over two drums,
one at each end of the chamber. This band =K= is driven from the pulley
shown by means of worm gear, and receives a traverse at its top side
in the reverse direction to the air current. On the band are fitted a
number of blades or teeth, between which the dust or dirt can fall.
The traverse of the lattice carries the dirt forward, and when the
teeth are turned downward it falls into the spout or receptacle =N=,
and on to the top of an iron flap =P=, usually kept in a horizontal
position by the balanced lever fitted on the spindle on which the flap
oscillates. The collection of a sufficient quantity of dirt destroys
the equilibrium and causes the flap to tip, allowing the dirt to fall
into a sack suspended below the orifice to receive it. In the event of
any dirt falling on to the bottom of the chamber, two or three special
blades are arranged to scrape along it and draw the dirt to the other
down spout =O=, where a similar action occurs. This arrangement has two
advantages. It constantly presents to the advance of the cotton new and
clean receptacles for the dirt, and it automatically removes the latter
from the path of the material. These are decided improvements, and the
arrangement is a considerable advance on its predecessor.
[Illustration: FIG. 21. J.N.]
[Illustration]