_Softening and Softening Machines_. Two distinct courses are
followed in the preparation of the jute fibre after it leaves the
bale opener, and before it is carded by the breaker card. These
courses are designated as--
1. Hand Batching.
2. Machine Batching.
In the former process, which is not largely practised, the pieces of
jute are neatly doubled, while imparting a slight twist, to
facilitate subsequent handling, and laid in layers in large carts
which can be wheeled from place to place; if this method is not
convenient, the pieces are doubled similarly and deposited in large
stalls such as those illustrated in Fig. 10.
On the completion of each layer, or sometimes two layers, the
necessary measured amount of oil is evenly sprayed by hand over the
pieces from cans provided with suitable perforated outlets--usually
long tubes. After the oil has been added, water, from a similar
sprayer attached by tubing to a water tap, is added until the
attendant has applied what he or she considers is the proper quantity.
The ratio between a measured amount of oil and an unmeasured amount
of water is thus somewhat varied, and for this reason the above
method is not to be commended. A conscientious worker can, however,
with judgment, introduce satisfactory proportions which are, of
course, supplied by the person in charge. In Fig. 10, the tank on
the right is where the oil is stored, while the oil can, and the
spray-pipe and tube for water, are shown near the second post or
partition on the right.
[ILLUSTRATION: FIG. 10 HAND-BATCHING DEPARTMENT WITH UNPREPARED AND
PREPARED FIBRE]
The first stall--that next to the oil tank--in Fig. 10 is filled
with the prepared pieces, and the contents are allowed to remain
there for some time, say 24 hours, in order that the material may be
more or less uniformly lubricated or conditioned. At the end of this
time, the pieces are ready to be conveyed to and fed into the
softening machines where the fibres undergo a further process of
bending and crushing.
All softening machines for jute, or softeners as they are often
called, are similar in construction, but the number of pairs of
rollers varies according to circumstances and to the opinions of
managers. Thus, the softener illustrated in Fig. 11, which, in the
form shown, is intended to treat jute from the above-mentioned stalls,
is made with 47, 55, 63 or 71 pairs of rollers or any other number
which, minus 1, is a measure of 8. The sections are made in 8's. The
illustration shows only 31 pairs.
The first pair of rollers--that next to the feed sheet in the
foreground of Fig. 11--is provided with straight flutes as clearly
shown. All the other rollers, however, are provided with oblique
flutes, such flutes making a small angle with the horizontal. What
is often considered as a standard softening machine contains 63
pairs of fluted rollers besides the usual feed and delivery rollers.
As mentioned above, this number is varied according to circumstances.
The lubricated pieces of jute are fed on to the feed roller sheet,
and hence undergo a considerable amount of bending in different ways
before they emerge from the delivery rollers at the other end of the
machine.
[Illustration: Fig. 11 Softening machine without batching apparatus]
Machine batching is preferred by many firms because the application
of oil and water, and the proportion of each, are much more uniform
than they are by the above mentioned process of hand batching. On the
other hand, there is no time for conditioning the fibre because the
lubrication and the softening are proceeding simultaneously,
although conditioning may proceed while the fibre remains in the
cart after it has left the softener.
The mechanical apparatus as made by Messrs. Urquhart, Lindsay & Co.,
Ltd., Dundee, for depositing the oil and water on the pieces or
"stricks" of jute is illustrated in Fig. 12. The actual lubricating
equipment is situated on the top of the rectangular frame in the
centre of the illustration. This frame is bolted to the side frames
of the softening machine proper, say that shown in Fig. 11. Its
exact position, with respect to its distance from the feed, is a
matter of choice, but the liquid is often arranged to fall on to the
material at any point between the second and twelfth rollers.
In Fig. 12 the ends of 13 rollers of the upper set are seen clearly,
and these upper rollers are kept hard in contact with the stricks or
pieces of jute by means of the powerful springs shown immediately
above the roller bearings and partially enclosed in bell-jars.
Outside the rectangular frame in Fig. 12 are two rods, one vertical
and the other inclined. The straight or vertical rod is attached by
suitable levers and rods to the set-on handles at each end of the
machine and to the valve of the water pipe near the top of the frame,
while the upper end of the inclined or oblique rod is fulcrumed on a
rod projecting from the frame. The lower or curved end of the
oblique rod rests against the boss of one of the upper rollers.
[Illustration: Fig. 12]
The water valve is opened and closed with the starting and stopping
of the machine, but the oblique rod is moved only when irregular
feeding takes place. Thus, the upper rollers rise slightly against
the pressure of the springs when thick stricks appear; hence, when a
thick place passes under the roller which is in contact with the
curved end of the oblique rod, the end moves slightly clockwise, and
thus rotates the fulcrum rod; this results in an increased quantity
of oil being liberated from the source of supply, and the mechanism
is so arranged that the oil reaches the thick part of the strick.
When the above-mentioned upper roller descends, due to a decrease in
the thickness of the strick, the oblique rod and its fulcrum is
moved slightly counter-clockwise, and less oil is liberated for the
thin part of the strick. It will be understood that all makers of
softening machines supply the automatic lubricating or batching
apparatus when desired.
A view of a softener at work appears in Fig. 13. The bevel wheels at
the end of the rollers are naturally covered as a protection against
accidents. In many machines safety appliances are fitted at the feed
end so that the machine may be automatically stopped if the
operative is in danger. The batching apparatus for this machine is
of a different kind from that illustrated in Fig. 12; moreover, it
is placed nearer the feed rollers than the twelfth pair. The feed
pipes for the oil and the water are shown coming from a high plane,
and the supply is under the influence of chain gearing as shown on
the right near the large driving belt from the drum on the shafting.
The feed roller in this machine is a spirally fluted one, and the
nature of the flutes is clearly emphasized in the view. The barrow
of jute at the far end of the machine is built up from stricks which
have passed through the machine, and these stricks are now ready for
conditioning, and will be stored in a convenient position for future
treatment.
[Illustration: Fig. 13 Softening machine with batching apparatus]
While the jute as assorted and baled for export from India is graded
in such a way that it may be used for certain classes of yarn
without any further selection or treatment, it may be possible to
utilize the material to better advantage by a judicious selection
and treatment after it has undergone the operation of batching.
What are known as cuttings are often treated by a special machine
known as a "root-opener." The jute cuttings are fed into the
machines and the fibre rubbed between fixed and rotating pins in
order to loosen the matted ends of stricks. Foreign matter drops
through the openings of a grid to the floor, and the fibre is
delivered on to a table, or, if desired, on to the feed sheet of the
softener.
The root ends of stricks are sometimes treated by a special machine
termed a root-comber with the object of loosening the comparatively
hard end of the strick. A snipping machine or a teazer may also be
used for somewhat similar purposes, and for opening out ropes and
similar close textures.
The cuttings may be partially loosened by means of blows from a
heavy iron bar; boiling water is then poured on the fibre, and then
the material is built up with room left for expansion, and allowed
to remain in this condition for a few days. A certain quantity of
this material may then be used along with other marks of jute to
form a batch suitable for the intended yarn.
A very common practice is to cut the hard root ends off by means of
a large stationary knife. At other times, the thin ends of the
stricks are also cut off by the same instrument. These two parts are
severed when it is desired to utilize only the best part of the
strick. The root ends are usually darker in colour than the remainder,
and hence the above process is one of selection with the object of
securing a yarn which will be uniform in colour and in strength.