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.
[Illustration:
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.
_Yarn Clearing._—On most winding machines for the hosiery trade are
placed in front of each spindle for winding a pair of upright plates
which comprise the yarn clearers YC, which are regulated in their
distance from each other by means of a small screw. The thread clearer
is shown in front section in Fig. 49 where the plates are marked YC,
their distance apart being regulated to a nicety by the small screw
marked X operated by the two fingers. These thread clearers are fixed
there so that by passing the yarn through between them on its way to the
bobbin B, thick places, burrs, slubs, etc., may be removed from the
yarns and extra large knots caught between them. In other words, the
function of the thread clearer may be stated as a qualifying of the
thread for its passage through the thread-carriers into the needles and
sinkers of the knitting frame, and by removing these obstructions in
winding, subsequent trouble in knitting is avoided and loss of time
averted. In many hosiery factories, however, it is noted that these
clearers are by no means in general use, and certainly if the yarn is in
anything like clean condition, it should be permitted to pass on to the
bobbin in an unruffled condition.
_Damping._—Damping is one of the subsidiary operations of hosiery
manufacture which, apparently of little account, may yet have serious
consequences if neglected or improperly performed. Manufacturers are
divided as to the merits of damping or lubricating as it is often
called, and in many progressive factories it is seldom if ever
performed. The object of damping is to soften those classes of woollen,
silk and cotton yarns which are deficient in pliability and do not allow
themselves to be formed into symmetrical loops. In the case of woollen
yarns some varieties are hard and unyielding, and when knitted in loops
they display small irregularities of stitch which are known popularly
under the term of pinholes. These occur irregularly all over the texture
and seriously impair its quality and lubrication or damping is found to
have a beneficial effect by giving greater elasticity and bending power
to the thread. The lubricating or damping agent varies according to the
type of yarn, woollen yarns are damped with an emulsion of oil and soap,
lard is often used for silk materials, whilst cottons are passed through
cakes of paraffin wax. For woollen yarns the lubricating is performed on
the winding machine by passing the yarn through a lubricating trough
marked N, Fig. 48, the trough being half filled with liquor marked L and
in which the roller R is made to revolve. The ideal emulsion for the
damping agent is olive oil and soft soap heated and mixed together to
form an emulsion, but the high cost of these commodities have placed
them out of the reach of practical work and now various substitutes are
employed. The roller R is made to revolve in the damping solution by
means of a band connected with the side drive of the machine, and this
brings a fresh supply of liquor into persistent contact with the thread.
The yarn should be worked on the frame as soon as possible after
winding, for when the bobbin has stood for twelve hours or so the liquor
begins to lose its effect due to evaporation, and if left standing
overnight the effect of the damping may to a considerable extent be lost
on a yarn.
_Evils of Damping._—The beneficial effects of damping dry and hard
woollen yarn is at once evident in the improved nature of the fabric,
but there are serious drawbacks to the indiscriminate adoption of the
process. Woollen yarn has considerable hygroscopic capacity and it laps
up this moisture very greedily, altering its physical properties
considerably in so doing. One effect of damping is to considerably
augment the elasticity and stretch of the yarn and this induces
variation in the dimensions of garments, introducing an unstable element
which is very difficult to gauge accurately. The sizes of garments tend
to vary considerably, and difficulty is experienced in seaming or
joining them together to have each side terminate equally. There are
also differences in the weight of the garments owing to the capacity
which the woollen fibre has of absorbing moisture far in excess of what
is recognized as essential, and the effect is to vitiate size
measurements. This gives rise to pants longer in one leg than another,
and one side of a seam going to a greater length than the neighbouring
one to which it has to be attached. The lubricating materials supplied
as substitutes have not always proved suitable, for in many instances
they fail to emulsify, and if the oil is left to go on to the yarn by
itself it causes stickiness if the brand proves to be inferior or
contains resinous substitutes. In the coarser varieties of hosiery yarn
which are spun in the grease, lubrication is not so essential, as the
yarn is quite pliable, but in the varieties known as dry-spun where
little or no oil is inserted in the sliver during preparation, damping
greatly improves the loop-forming propensities. It would seem that a
certain amount of fat is essential to the fullest possession of the wool
fibre of all its important properties; in wool scouring the natural fat
or yolk of the material is extracted, and if this be not replaced at a
subsequent stage of spinning or knitting, the resilient properties are
seriously diminished. In dry spinning we have greater cleanliness of
yarn, but what is gained in cleanness is lost in resilience and
pliability, and to restore these physical properties the natural oil or
fat present in the cells of the fibre is artificially replaced by a
soap-oil emulsion. In the case of silk it is often found that the
crispness of fibre and the frictional resistance cause the fibres to
resist the curves of looping and a form of electricity is generated
during the contact of the silk material with the needles of the frame.
In such cases when the quality of stitch is seriously impaired the yarns
are passed through cakes of lard on their way to the winding bobbin
which has the effect of greatly improving the knitting qualities of the
yarn, the loops being at once transformed from half-made and rugged
structures into perfectly-arched specimens.