(107) The cylinder E is made from 40in. to 50in. diameter, and from 37in. to 50in. wide. It consists of a cylindrical shell, strengthened throughout its length by small internal ribs, and having near its edges a flange formed. Its position is clearly shown in Fig. [46], and the way in which it is built in Fig. [51]. The inner part of the ends of the cylinder and the face of the vertical flanges are bored out accurately by a specially constructed machine. Into each of these recesses a spider is fitted, consisting of a central boss, arms U, and rim V. The boss is first bored to the size of the shaft upon which it has to fit, and the edge and inner face of the rim are turned to a size corresponding with the recess in the cylinder. The two spiders so prepared are fitted into their places, and are then securely bolted to the cylinder. In this way a firm and accurate fit is secured. A mandrill is fitted into the bosses, and the cylinder is then turned truly on its face. After the shaft is fitted in it is sometimes the practice to grind the face of the cylinder, but, if the needful care is taken in turning it, this is not necessary. It is essential that the periphery of the cylinder shall be rigid, but it is equally important that the latter shall not be too heavy. A velocity ranging from 140 to 200 revolutions per minute is given to it, and it is clear that lightness and perfect balance are alike important. After the turning is completed the surface of the cylinder is drilled with a number of rows of holes about half an inch diameter, into which wooden plugs are driven, so as to facilitate the “clothing” of the cylinder. As a rule the latter is balanced, or rather tested for its balance, by running it at its working speed in bearings which slide when the equilibrium is disturbed. When working, the direction in which the cylinder revolves is indicated by the arrow in Fig. [46], and the cotton is carried from the licker-in B to the doffer F, being treated on its way thither by a special set of teeth, the arrangement of which will be hereafter described.
(108) The doffer is a cast-iron roller, 22in. to 26in. in diameter, the same width as the cylinder, and is placed as shown at F. The doffer is constructed and clothed in a similar way to the cylinder. It revolves, as shown by the arrow, in the contrary direction to the cylinder, and at a much slower rate, making usually about twelve revolutions per minute. In this way the carded fibres are transferred from the cylinder to the doffer, and are placed on the surface of the latter in a thin fleece. The removal of the latter is effected by a narrow thin steel blade G, Fig. [44], known as the “doffer comb,” which is fixed on the ends of short arms fastened on a shaft carried by bearings at each end. A rapid oscillatory motion is given to the comb by means of an eccentric or cam, driven from a pulley on the cylinder by a cord or band, the number of beats per minute reaching 1,100. An arc of about an inch long is described by it, and in this way a continuous fleece, called the “sliver,” is taken off the doffer.
(109) The sliver is loosely gathered together into a strand by means of a specially shaped plate, and passed through a pair of calender rollers H Fig. [44] by which it is partially compressed. A slight traverse is sometimes given to the trumpet-shaped tube through which the sliver is taken to the calender rollers. After leaving the latter the sliver is taken upwards to an opening in the plate at the upper part of the frame I. This frame forms part of the apparatus known as the “coiler,” which is illustrated in vertical section in Fig. [45].
(110) The coiler consists of a frame I within which is a vertical shaft V driven by means of the short horizontal shaft from the calender rollers. At the upper end of the shaft a second pair of bevelled wheels are geared, which drive the calender or feed rollers placed immediately below the trumpet-shaped orifice in the cover T, which is hinged as shown. One of the rollers is supposed to be removed in order to show the arrangement more clearly. The sliver entering by the orifice in T and, passing the rollers, is delivered into a short tube X forming part of the plate Z. The latter is driven in the direction shown by the arrows by means of the spur wheel Y gearing with a rack formed on the edge of the coiler plate Z. The sliver is thus given a slight twist, and is delivered into the can W, placed on a plate free to revolve and borne in the lower part of the coiler frame. The can is placed eccentrically to the coiler plate Z, and is slowly revolved in the opposite direction to it, as indicated by the arrows. In this way the sliver is laid within the can in coils, which are peculiarly disposed so that they do not become entangled. Often, within the can, a pair of discs, coupled by a coarsely pitched helical spring, are placed, upon which the cotton is received. The object of this device is to relieve the strain upon the sliver, which would otherwise arise if it were unsupported as far as the bottom of the can. As the weight comes upon the upper disc the spring compresses.
(111) The parts thus described are common to all cotton carding machines, and would remove the major portion of the motes and heavier impurities, but only a partial parallelisation of the fibres would occur; nor would more than a small portion of the short, broken, or immature fibres or “neps” be removed. It therefore becomes necessary to devise a means by which, while the cotton is on the cylinder, it may be treated so that the completion of the cleansing and the arrangement of the fibres are carried out. In order to do this the fibres must be submitted to a combing process, by which, while held by the cylinder teeth, another set of teeth act upon them. The form of carding engine which first found extensive employment, and which is yet preferred by many spinners, is known as the “roller and clearer card.” This machine is illustrated in Fig. [47], as made by Mr. John Mason, in perspective, and in Fig. [46] diagrammatically. After the cotton has been taken from the licker-in B by the cylinder E it is carried past a roller J, known as a dirt roller. The diameter of this is from 5in. to 6in., and it revolves at about eight revolutions a minute. When the fibres are taken up by the cylinder wire, they are partially embedded in the interstices of the clothing, but the motes remain on the surface, from which they are easily removed. The dirt roller J takes these up, and, being covered with a coarser pitched wire than E, the motes become fixed in the former, from which they can be stripped. This can be effected by a hand comb at regular intervals, or by an oscillating comb suitably operated in the way made by Messrs. John Hetherington and Sons, as illustrated in Fig. [48] (page 60). In this case the dirt roller A is driven by a side shaft by means of the worms B and D, the latter gearing into the wheel E, which is keyed on the dirt roller spindle. A cam F fixed on the first working roller gives a reciprocating motion to the rail G by which the comb H is operated, the roller J being thus stripped. An iron tray I is fixed, as shown, into which the strippings fall.
Fig. 46.J.N.
Fig. 47.
(112) After passing the dirt roller the cotton is treated by the teeth on a smaller roller, K, known as a “worker” roller, which revolves in the direction of the arrow. Each worker has a smaller roller, L, placed in contact with it and called a “clearer.” The teeth on the worker have an inclination which is the reverse of those on the cylinder, and any cotton which is not fixed in the wire surface of the latter, or which is flung up by the centrifugal action of the cylinder, is seized by the worker teeth and removed. The worker revolves at a slower speed than the cylinder, its surface velocity being about 20 feet per minute, and varies in diameter from 5 to 6 inches. The clearer, which is 3 or 31⁄2 inches in diameter, has its teeth set in the same direction as its motion, and its surface speed being about 400 feet per minute, it takes the cotton from the worker and again transfers it to the cylinder. As the surface velocity of the latter is higher than that of the clearer, the cotton is struck by its teeth and is drawn off the clearer and carried forward to the next pair of rollers. It should be pointed out that, although the cotton on the cylinder passes the clearer before it reaches the worker, the inclination of the clearer teeth is such that they cannot take up the fibres; while, on the other hand, the worker teeth are so set that, as previously pointed out, they take up the fibres from the cylinder. Again, the different velocities off the workers, clearers and cylinders cause a series of condensations and attenuations of the fleece to occur. The short fibres and “nep” are laid hold of, and are either sufficiently loosened to be thrown off as “fly,” or are embedded in the teeth of the workers and clearers, which, in consequence, require periodical stripping, this being usually effected manually. The setting of the rollers must be such that they do not approach the cylinder too closely, but simply deal with the fibres thrown up by the revolution of the cylinder. The lighter the carding, provided cleanliness is achieved, the better for the cotton, as with too heavy carding considerable damage is done to the material.