Fig. 47
YARN SPUN FROM NETTLE FIBRE
Requirements of the Fancy Trade.—In the chapter on woollen underwear yarns the characteristics of material and structure were discussed in relation to the trade in underwear. In this chapter a number of materials have been referred to which take their place in the what is known as the fancy trade for outer and intermediate garments. If it is a question of the fancy stitches, it is required to bring out the features of these with yarns clear in surface and neat in structure so that the eye may follow the intersections of the yarns in the fabric. The silk and artificial silk productions belong to the most highly valued of the ornamental branches of the knitting industry, and these may be utilized to bring out in the clearest effect stitches such as shogged patterns, rib varieties and lace designs where definiteness of stitch and brilliance of colour combine to give results of a high value for elegant garments. In the case of materials of camel hair, Angora fur or pure cashmere class, the stitch as a rule is subsidiary, being usually of the plainest description so as to allow of the fullest display of the natural properties of the material. In the fancy trade it is futile to employ features which compete with each other for the attention of the observer. In a fancy-stitch article the mono-colour should prevail; where the stitch is simple the best ground is afforded for the display of several colours in the goods.
CHAPTER X
Hosiery Yarn Winding
In former chapters it has been pointed out that the knitted stitch is apparently a simple structure, but on closer examination a number of elements are discovered which together form a complex whole. In the knitting operation the chief essential is accuracy of loop formation and regularity of stitch right along the entire width of loops in the course. If at any point the thread is drawn slightly tighter than the normal, this tightening is at once apparent in the formation of the loops and a grave defect occurs which on account of its minuteness is impossible to remedy in after operations. In the knitting operation correct tension of thread is indispensable to good quality fabric, and this again depends on an absolutely uniform feed of yarn to the needles of the machine. In this yarn supply one of the first essentials is a proper package for the yarn and one which will insure that the thread unwinds with absolutely even tension throughout. It is a very serious matter indeed to the hosiery manufacturer if even slight obstacles occur on the bobbin for these at once injure the fabric quality. Another frequent cause of defects occurs by what is termed the ballooning of the thread as it comes from the bobbin, that is, the swing which the thread makes in unwinding itself when it encounters the resistance of the air, a matter which depends on the bulk of the thread and the amount and nature of its surface fibre. It also varies according as the bobbin is full or nearly empty with intermediate stages of differential variation. So important is this matter of uniform yarn feed recognized to be for first-class fabric, that the Americans in particular have given the utmost attention to yarn supply devices, by which the yarn is measured into the needles by an arrangement which deadens all the minor variations of tension before the yarn approaches the sinkers and needles, and the amount fed into the needles is measured absolutely level for each stitch. There is also a growing disinclination amongst manufacturers to undertake the winding of yarn owing to the loss incurred by imperfect work, and this branch is being more and more relegated to the spinner who delivers the material in a form ready to work on the frame. Of course in a varied class trade it will be found impossible to eliminate the winding operation entirely, for we have the problem of the conservation of small quantities of yarn and their subsequent working into fabric. One of the chief difficulties of the winding department is the correct piecing of the ends with a minimum of waste and this department has been largely left to young workers as their first job in entering the factory. With the enormous rise in the prices of yarns manufacturers are now recognizing that the operation has developed from a subsidiary to a primary one, and better results are being obtained by having the winding performed by older and more experienced workers who have a correct idea of the value of the material and are properly schooled in the avoidance of waste. With inexperienced workers much weekly loss is caused not only by the waste incurred in piecing the ends but also because these knots are not properly secured or are ragged in appearance. Very often they are quite firm, but on account of their size are unable to pass through the eye of the thread-carrier or if they do emerge successfully from this ordeal the chances are that the sinkers will refuse to take them in, and the needles bend or breakage of the springs result. If the knot does get safely into the fabric, the trouble is by no means finished, for if it is untidy in appearance it lowers the quality of the fabric and reduces the saleability. A frequent point of danger is the eye of the thread-carrier which is fine in aperture, and unless the knot is of reasonable size, it stands a strong chance of causing a press-off on the machine, with loss of time in having the fabric picked on again added to the loss due to stoppage of the other machine sections. What is probably worse in effect is the momentary tightening of the loops due to the knot being caught in the eye of the thread-carrier which usually takes the form of several inches of stitches attenuated in length compared with the rest of the fabric and which constitutes an instant blemish on the fabric texture quality. The chief waste in winding is made when piecing the two ends together when it requires skill to perform the operation of knotting with the finger tips so as to employ less material. The primitive mode is to bring hands, wrists, and even the elbows into play with a considerable amount of waste incidental to the process. With yarns at 12/-per lb. a careless worker can soon dissipate a considerable amount of money in waste and it is advisable to have some form of checking the waste made by any particular worker so as to form a proper estimate of their individual efficiency.
The Winding Operation.—Sufficient has been stated to indicate that the winding of yarn usually regarded as subsidiary in other branches of textiles is a first essential in the knitting business. An evenly-wound package is of great importance, and in regard to the size of bobbin conditions are quite different to those prevailing in the weaving trade. In weaving the weight of the package is restricted to the capacity of the shuttle, this being limited in size so that the weight may be kept at the minimum required for throwing across the lay of the loom. In knitting the position is more favourable, for the bobbin or yarn package is usually stationary and the thread is drawn from it to be fed into the needles of the frame. For this it is naturally an advantage to have the package as large as possible so as to reduce to the lowest minimum the time required for changing from an empty bobbin to a full one. To insure uniformity of yarn delivery to the needles and sinkers it is essential to have a perfectly built bobbin, and for the older types of winding frames, the usual shape was a bobbin with a high centre where the yarn got frequently caught in the grooves or on the bottom end. This primitive system of yarn winding was not unsuitable for the coarser types of knitting yarns in the stout gauges, and for this work the older form of winder is found in many of our factories even to-day. This machine has the advantage of being simply constructed and easily manipulated by an unskilled worker, and it is also rapid in action.
Figs. 48 and 49
The Modern Hosiery Winder.—In the hosiery trade there is practical unanimity as regards the type of machine most suitable for the general purposes of a knitting factory, and herewith in Fig. 48 is given a side view of a section of the chief functional parts of a machine which enjoys a large popularity with manufacturers as having proved itself immensely suitable for general purposes. It is somewhat vaguely known as the Foster winder, made with variations by a number of firms, and through each the leading principles of construction are the same. The bobbin is marked B, and is of the type invariably employed in the underwear trade, this being placed on a spindle where it is kept in position by a groove which fits the shape of the metal part on which it rests. Further down in the machine the friction wheel FW is attached, this being in the form of a circular disc rotated by the driving wheel marked DW. This wheel has its rim covered with rough leather so that it can turn the wheel or disc FW and so cause the bobbin B to revolve. In front of the bobbin is a finger operated by the worker which has the effect of raising the friction disc FW away from the driving wheel DW, thus bringing the bobbin to a standstill. The yarn is indicated by T which is seen to pass upwards from the hank H which is stretched over the racers U. On the way to the bobbin the thread passes successively between the plates of the yarn-clearing apparatus YC, over the roller R, and then through the eye of the guide G direct to the bobbin.
Bobbin Building.—The outstanding advantage of this machine is the efficient manner in which the bobbin is built, and in this process several factors have to be considered. The thread guide G has a regular up-and-down motion for the traverse, this upward and downward sweep being brought about by the heart-shaped cam C which, by its revolving action, causes the whole stage P to rise and fall, thus giving a similar motion to the thread guide. Partaking in this traverse is the spiral S with the wheel W, which has a ribbed surface to preserve contact with the yarn level. The wheel W has a finger V attached, which in turn works into the spiral of rod S, and whenever the yarn rises to a certain level on the bobbin, it comes into frictional contact with the ribbed wheel which receives a turn sufficient to cause the wheel and guide to rise higher on the spiral and with it the thread guide also assumes a more elevated position. In this way the wheel W and the thread guide G travel from the lower end of the spiral S to the other upper end during the operation of filling a single bobbin. Up to this stage the action may be detailed thus: the thread guide receives its traverse over a certain distance of the bobbin by the action of the heart-shaped cam C, this being denoted by the dotted positions C1 for cam, K1 for stud, P1 for the stage, G1 for the guide, and this motion proceeds regularly during the winding operation. There is next the gradual rising of the guide on the spiral rod caused by the turning of the bobbin B, the high part of the bobbin B having friction with the ribbed wheel W causing it to rise gradually on the spiral.
The Differential.—The final element in successful bobbin building is the differential and the means of securing this are ingenious in the highest degree. The driving wheel DW with its rough leather rim works on the disc FW and causes it to rotate, but the speed of rotation must vary according as the upper or the lower part of the bobbin is being filled. When the yarn is passing on to the bare part of the bobbin as it does at the upper sweep of the traverse, one revolution coils a very much smaller length of thread than it does at its lowest position when the bobbin is full. The rate of winding varies differentially according to the intermediate positions of the thread, in the upward sweep of the traverse the speed of the bobbin accelerates as the bare part is approached, whilst on the downward sweep the speed of the bobbin decreases, reaching its slowest when the full part of the bobbin is attained. This differential is produced by a side-to-side movement of the driving wheel DW over the rim of the disc FW, from the outer rim and slowly towards the inner rim and vice versâ. When the wheel is driving at its extreme position on the outer rim the bobbin is running at its slowest, because the driving wheel has a longer distance to traverse in order to effect one bobbin revolution. When the driving wheel is acting at its furthest position inwards the bobbin is at its highest speed, and this takes place with graduated differences in the intermediate stages of the process.