The Story of the Cotton Plant Part 8

=Cotton Mixing and the Bale Breaker.=--As before stated, the first operation in the mill is the opening out of bales of raw material and making a "mixing." Of course the weight of the bale is ascertained before it is opened.

All varieties of cotton vary in their commercial properties, this variation being due to a number of causes. From a commercial value point of view, there is an enormous difference between the very best and the very worst cottons; so much so, indeed, that they are never blended together. Between these two extremes there is a well-graded number of varieties and cla.s.sifications of cotton, and some approximate so closely to others in quality, that they are often blended together in the "mixing."

Further than this, the same cla.s.s of cotton often varies in spinning qualities from a number of circ.u.mstances that need not here be named.

This is, however, an additional reason why cotton from various bales should be blended together in order to secure uniformity.

A cotton "mixing" may be described as a kind of "stack," resembling somewhat the haystack of the farm yards.

The method usually pursued in making this mixing is somewhat as follows:--A portion of cotton from a certain bale is taken off and spread over a given area of floor s.p.a.ce. Then a similar portion from another bale is placed over the first layer already lying on the floor.

The same operation is followed with a third and fourth layer from different bales, and so on with as many bales as the management consider there are variations in quality, the larger the mixing the better for securing uniformity of yarn.

When it is desired to use the cotton, it should be pulled down vertically from the face of the "mixing," so as to secure a fair portion from each bale composing the mixture. Before spreading the cotton out it is usually pulled into pieces of moderate size by the hands of the operative.

During recent years it has become the very general practice to use a small machine called the "Bale Breaker" or "Cotton Puller," and to have also working in conjunction with this machine long travelling "lattices"

called "mixing lattices." These perform the operation of "pulling" and "mixing" the cotton much more quickly and effectively than by hand labour.

The "Cotton Puller" or "Bale Breaker" (see Fig. 12) simply consists, in its most useful form, of four pairs of coa.r.s.ely fluted or spiked rollers of about 6 inches diameter with a feed ap.r.o.n or lattice such as is shown in the ill.u.s.tration.

Image: FIG. 12.--Bale breaker or puller.

The method adopted with the "Bale Breaker" and "mixing lattices" in use is as follows:--

The various bales of cotton intended for "mixing" are placed very near to the feed ap.r.o.n of the Bale Breaker, and a layer from each bale in succession is placed on the ap.r.o.n. The latter feeds the cotton at a slow rate to the revolving rollers of the machine, and as each pair of top and bottom rollers that the cotton meets is revolving more rapidly than the preceding pair, the result is a pulling asunder of the cotton by the rollers, into much smaller pieces, quite suitable for the next machine.

The Bale Breaker delivers the cotton upon long travelling ap.r.o.ns of lattice work, which carry the cotton away and deposit it upon any desired portion of the floor to form the "mixing."

=Opening.=--The name of the next process, viz., "opening," has been given it because its primary function is "to open" out the cotton to such an extent that the greater bulk of the seed, leaf, sand, and dust is readily extracted. The details of this machine and indeed practically of all machines used in cotton spinning, vary so much with different makers, that it would be utterly out of place to deal with them here, so that it may be said at once, that all such points are entirely omitted from this treatment of the subject.

The essential and princ.i.p.al portions of the machines are practically identical for all makers, and it is with these only that it is proposed to deal, taking in all cases the best present-day practice.

The opener, then, is a very powerful machine, being in fact the most powerful used in cotton spinning, and the most important feature of the machine is the employment of a strong beater, to which is fitted a large number of iron or steel knives or spikes. These beat down the cotton and open it at a terrific rate, the beater having a surface speed of perhaps 4000 feet a minute. Various fans, rollers, and other parts are employed to feed the cotton to the beater, and to take it away again after treatment. It will perhaps best serve the purpose of our readers if the pa.s.sage of the cotton be described through an opener of the most modern and approved construction, dealing with the subject in non-technical terms.

With this object in view, take for example what is termed "The Double Cotton Opener" with "Hopper Feed Attachment." This machine is shown in Fig. 13.

Image: FIG. 13.--"Double opener" with "hopper feed."

The Hopper Feed is about the most recent improvement of any magnitude generally adopted in cotton spinning mills. It is an attachment to the initial or feed end of an opener with the object of feeding the cotton more cheaply and effectively than it can be done by hand.

It may be said to consist of a large iron feed box, into which the cotton is pa.s.sed in considerable quant.i.ties at one time. At the bottom of the feed box, or hopper, is a travelling ap.r.o.n which carries the cotton forward, so as to be brought within the action of steel pins in an inclined travelling ap.r.o.n or lattice. This latter carries the cotton upwards, and special mechanism is provided in the shape of what is termed an "Evener roller," to prevent too much cotton going forward at once.

The cotton that pa.s.ses over the top of the inclined lattice or ap.r.o.n is stripped off by what is denominated the stripping roller, and is then deposited on the feed ap.r.o.n of the opener, where formerly it was placed by hand.

It may be said that one man can feed two machines with Hopper Feeds as against one without them, and in the best makes the work is done more effectively.

The feed lattice of the opener carries the cotton along to the feed rollers, which project it forward into the path of the large beater. It is here that the opening and cleaning actions are chiefly performed.

The strong knives or spikes of the beater break the cotton into very small portions indeed, and dash it against "cleaning bars" or "grate bars" specially arranged and constructed. Through the interstices of these bars much of the now loosened seed and dirt present in the cotton pa.s.ses into a suitable receptacle, which is afterward cleaned out at regular intervals.

The opened and cleaned cotton is taken away from the action of the beater by an air current produced by a powerful fan. This latter creates a partial vacuum in the beater chamber by blowing the air out of certain air exit trunks specially provided. To supply this partial vacuum afresh, air can only be obtained from the beater chamber, and the air current thus induced, takes the cotton along with it, and deposits it in the form of a sheet upon what are termed "cages" or "sieve cylinders."

These are hollow cylinders of iron or zinc perforated with a very large number of small holes through which the air rushes, leaving the cotton, as it were, plastered on the outer surfaces of the cages.

It is usual to have a pair of these cages, working one over the other like the pair of rollers in a wringing machine.

The cotton now pa.s.ses between two pairs of small guide rollers, and is fed by the second pair to a second beater, but of very different construction from the first one.

This consists of two or three iron or steel blades extending the full width of the machine and carried by specially constructed arms from a strong central shaft.

The edges of these beater blades are made somewhat sharp, and they strike down the cotton from the feed roller at the rate of 2000 or more blows per minute.

This of course carries the opening work of the cotton of the first beater to a still further degree, and as in this case the cotton is also struck down upon "beater bars" or cleaning bars, a further quant.i.ty of loosened impurities pa.s.ses through the bars. As before, another powerful fan creates an air current by which the cotton is carried away from the beater and placed upon a pair of "Cages." From this point the cotton is conducted in the form of a sheet between four heavy calender or compression rollers, the rollers being superimposed over each other, and the cotton receiving three compressions in its pa.s.sage.

This makes a much more solid and tractable sheet of cotton, and it is now simply wound upon an iron roller in the form of a roll of cotton termed a "lap," being now ready for the subsequent process, as shown in the ill.u.s.tration (Fig. 14).

Image: FIG. 14.--Scutching machine with "lap" at the back.

=Scutching.=--This term obviously means beating, and the process itself is simply a repet.i.tion of the opening and cleaning properties of the opener, these objects being attained to a greater degree of perfection.

For the best cla.s.ses of cotton it is often deemed sufficient to pa.s.s it through the opener alone, and then to immediately transfer the lap to the process of carding. For some cottons it is the practice to pa.s.s the cotton through two scutchers in addition to the opener, while in other cases it is the practice to use one scutcher only in addition to the opener.

In the scutcher it is the most common practice to take four laps from the opener and to place them in a specially constructed creel and resting on a travelling "lattice" or ap.r.o.n. By this they are slowly unwound and the four sheets are laid one upon another and pa.s.sed in one combined sheet, through feed rollers, to a two or three bladed beater, exactly like the second one described when treating upon the double opener. Also, exactly in the same manner, a lap is formed ready for the immediately succeeding process of carding. In the scutcher the doubling of four laps together tends to produce a sheet of cotton more uniform in thickness and weight than that from the opener. This object of equality of lap is also invariably aided by what are termed Automatic Feed Regulators, which regulate the weight of cotton given to the beater to something like a continuous uniformity. The action is clearly seen in the ill.u.s.tration.

=Carding.=--By many persons this is deemed to be the most important operation in cotton spinning. Its several duties may be stated as follows:--

1. The removal of a large proportion of any impurities, such as broken leaf, seed and sh.e.l.l, that may have escaped the previous processes. It may usually be deemed to be the final process of cleansing.

2. To open out and disentangle the cl.u.s.ters of fibres into even greater individualisation than existed when first picked, and to leave them in such condition that the subsequent operations can easily draw them out, and reduce them to parallel order.

3. The extraction of a good proportion of the short, broken and unripe fibres, present more or less in all cottons grown, and practically worthless from a manufacturing point of view.

4. The reduction of the heavy sheet or lap of cotton from the scutcher, into a comparatively light and thin sliver. Ordinarily, one yard of the lap put up behind the card weighs more than 100 times as heavy as the sliver delivered at the front of the card.

There are several varieties of Carding Engine, but in each case nearly all the essential features are practically the same in one card as in another. At the present time, the type of Carding Engine which has practically superseded all others is denominated the "Revolving Flat Card." This Card originated with Mr. Evan Leigh, of Manchester, and after being in close compet.i.tion with several other types has almost driven them out of the market. Of course it has been considerably improved by later inventors, and various machine makers have their own technical peculiarities.

In the ill.u.s.tration seen in Fig. 15 there is conveyed an excellent idea of the appearance of the heavy lap of cotton as it is placed behind the Carding Engine, and of the manner in which the same cotton appears as a "sliver" or soft strand of cotton as it issues from the front of the same machine, and enters the cylindrical can into which it is pa.s.sed, and coiled into compact layers, suitable for withdrawal at the immediately succeeding process.

Image: FIG. 15.--Two views of the carding engine: upper view, cotton entering; lower view, cotton leaving.

In the main, the parts which operate upon the cotton fibres in their pa.s.sage through this machine consist of a number of cylinders or rollers of various diameters, but practically equal in width. Some of these rollers are merely to guide and conduct the cotton forward, but the more important are literally bristling all over with a vast number of closely set and finely drawn steel wire teeth, whose duty it is to open, and comb out, and clean the fibers as they pa.s.s along.

To begin with, the "lap" or roll of cotton is placed behind the machine so as to rest on a roller of 6 inches in diameter, which slowly unwinds the lap at the rate of about 9 inches per minute, by frictional contact therewith.

Here, it may be said that the width of this and other chief rollers and cylindrical parts of the card may be about 38 inches or 40 inches wide, there being a tendency to make present-day Carding Engines rather narrower than formerly, in order to give greater strength to certain parts. From the lap roller the sheet of cotton is conducted for about 8 inches over a smooth feed plate, and then it goes underneath a fluted roller of 2-1/4 inches diameter, termed the feed roller, having practically the same surface speed as the lap roller, or possibly a small fraction more to keep the cotton lap tight.

At this stage the actual work of the Carding Engine may be said to commence. While the feed roller and the feed plate hold the end of the sheet of cotton and project it forward at the slow rate of 8 or 9 inches per minute, this projecting end of the lap becomes subject to the action of a powerful roller or beater termed the taker-in or licker-in.

The most recent and improved construction of this roller is termed the Metallic Taker-in, and it is covered all over with strong steel teeth shaped something like those of a saw. It is about 9 inches in diameter, and its strong teeth strike the cotton down from the feed roller with a surface speed of nearly 1000 feet per minute.