_Looms Should Be Adapted to Make a Wide Variety of Goods—Take-Up and
Let-Off Motions—Making the Rubber Warps for Different Classes of
Web—Importance of Uniform Tension—Defects from Uneven Tension and Chafing
of Threads_
The greatest care is necessary in planning out the details of the
harness. On account of the great length it becomes necessary that
everything possible be done to avoid any chance of warping or sagging,
for the least irregularity which may be developed will of course
interfere with the evenness of the shed. The harness frames must be made
of the very best stock obtainable, thoroughly seasoned, and absolutely
straight grained. Each frame must be supported at regular and frequent
intervals by stays or supports mortised in the runners. These stays
are slotted at top and bottom to receive the heddle bars and keep
them accurately in line, and thus prevent them from catching on the
neighboring harness during the operation of the shedding process.
It is necessary also that the top and bottom heddle bars be accurately
spaced so as to allow proper freedom for the heddles to ride easily
on the bars, and thus avoid any binding of heddles which would have a
tendency to crowd the warp stock together and prevent clearance of the
shed. Steel heddles are preferable to ones that bend and twist more or
less and get out of alignment. They are made from tempered steel which is
very flexible and they have round cornerless eyes that cannot possibly
catch or chafe the warp threads. They adjust themselves automatically
to the frame and cannot twist or bend while at work, and are made to
accommodate themselves to every conceivable kind of goods.
INSTALL LOOMS FOR WIDE RANGE
In installing looms for narrow elastic fabrics it is advisable to make
ample provision for creeling the warps necessary for the different
fabrics which may from time to time be required. In the manufacture
of the light single cloth garter webs, not more than two warps to the
piece are required, a face warp and a gut warp, and the temptation to
save a little in the initial cost possibly may suggest a limitation of
creel spaces to immediate requirements. Added expense may seem for the
time being an unnecessary burden. But very soon there may arise a call
for other goods which cannot be made within the limitations of the two
bank creel; therefore changes become necessary which are generally much
heavier than first cost would have been.
Nothing less than a five bank creel should be installed. Many times the
availability of six banks has solved knotty problems of warp division to
care for the various weaves and materials employed in some constructions.
If the entire capacity of the larger creel is not required when first
starting it will not be necessary to clothe all of it with levers,
buttons, etc., which may be procured later. But by all means ample
provision should be made for the full frame work and supporting rods for
same.
TAKE-UP MOTION
Another important consideration is to make proper provision for a
reliable take-up motion, so that the goods may be taken away from the
reed while weaving without any liability to variableness. This liability
was present in many of the earlier looms and exists in some of the
mills today. The old-time fine ratchet gear, even when provided with
a number of pawls, is always liable to erratic picking, which alone
will ruin an otherwise perfect piece of goods and materially change
the cost of manufacturing. A slight irregularity of picking may not be
discernible in non-elastic goods, which will be satisfactory so long as
the variableness is not easily seen and a reasonable average of picks per
inch is maintained. But in elastic goods, where the contraction takes
place after they leave the press rolls, every irregularity is revealed
and intensified so there is no room to take chances. The only safe way is
to employ picking gears making one tooth to each pick of the loom, and
then to change the gears when different picking becomes necessary.
In many of the existing looms there has been no adequate provision
made for the weaver to let the web back to the reed mechanically when
a joining becomes necessary through the breaking of the filling while
weaving, or where a quill may have run off unnoticed. It is almost
impossible to make a joining satisfactorily without proper mechanism
being provided for this purpose. In some of the slow running looms
provision is made for this by the operation of each set of rolls
independently (see Fig. 1), by means of the ratchet gear and pawl A and
worm motion B. This plan has the one disadvantage of taking up too much
space between the individual pieces. Where the fabric woven is say four
or five inches wide, and the space will admit, it is all that can be
desired, and the individually weighted rollers C associated with the
motion are admirably adapted to variable pressure.
For the very narrow elastic fabrics, which require considerable roller
pressure to hold the web snug and firm while weaving, and where it is
necessary to make very accurate joinings after a break has occurred,
a better movement is one in which the web roll is placed on the main
take-up shaft in the form of a sleeve. It is carried around by the shaft
as it turns while the goods are being woven, but can be released and
turned both backwards and forwards by a conveniently placed hand wheel,
which operates a series of differential gears. This movement is entirely
independent of the movement of the main take-up shaft drive.
TENSION ON RUBBER WARP
Too much importance cannot be attached to properly controlling the
tension of the rubber warp. On its uniformity depends not only the
quality, but also the cost of the web. The greater the weight of slack
rubber woven into the web the more costly it becomes and the poorer
the quality. A very accurate sense of touch is required in testing the
tension of the rubber threads as they are being delivered into the goods.
The rubber warp requires the highest possible tension before breaking or
chafing of the thread takes place. Each rubber thread should be under
this high tension so that when the goods come through the press roll the
desired contraction will take place uniformly, and a flat piece of web
will be produced that will have plenty of life.
It must always be remembered that the individual threads of rubber which
constitute a rubber warp will act as a series of small springs, working
in unison with each other. Each one should have equal power to contract
the fabric at its own particular part. If any one of these strands or
springs is chafed and weakened, it lessens the contracting power, and
the result is that the weakened or less contracted part is of relatively
greater length than the parts where the rubber threads have retained
their full power.
Moreover, the appearance of the goods will be spoiled by the chafed
particles of rubber pricking through the face, particularly on the white
and lighter colored goods. Before such webs can be marketed they must be
subjected to a buffing operation to remove these dirty particles, which
is accomplished by passing them over a highly speeded, cloth covered
roller, which will remove the loose particles by friction and high
velocity. But this operation adds to the cost.
A high and uniform tension of the rubber warp is so important that most
manufacturers keep men specially employed in the testing of the threads,
instead of leaving this matter to the weavers. These testers acquire
such a keen sense of touch that they can obtain very economical and
satisfactory results. Talc or soapstone is freely used as a lubricant to
reduce the risk of chafing and breaking of the rubber threads. The warps
are arranged so as to allow the threads to pass through a bed of plush,
loaded with talc, which adheres to the rubber threads and makes them work
very smoothly. This is especially important in damp weather, which is the
worst condition for the weaving of elastic goods. At times factories have
stopped operations when the weather was especially humid.
LET-OFF MOTION
[Illustration: Fig. 1.—Individual Take-Up Motion for Wide Space Looms]
[Illustration: Fig. 2.—Individual Rubber Warp Let-Off Motion]
When we remember that the front reed will pass by the rubber threads
possibly six or seven hundred times from their entrance into the shed
to their reaching the leaving line, it is not to be wondered at that
chafing is liable to take place. With all this liability of spoiling
goods it becomes readily apparent that any device employed to regulate
such an important feature as the tension of the rubber warps must be very
sensitive and dependable.
On looms making wide goods, and where space will allow, regulation is
accomplished by a worm and gear movement as shown in Fig. 2. The iron
rubber beam is threaded on to a square shaft A, at one end of which a
gear wheel B is fastened. In this gear is meshed the worm C, which is
operated by a heavy linen cord D passed twice around a pulley E. The cord
derives its movement from a rocking shaft F, on which there is fastened a
screw extension G, by which adjustment can be made so as to deliver very
accurately any amount from the rubber beam.
With this kind of movement, and in order to feed the thread uniformly
into the web, it becomes necessary to use mechanically made warps where
the same uniformity has been maintained in putting the warps on the
beams. The warps so made must come from the thread manufacturer in
individual warps, which are done up in chain form, each warp containing
the requisite number of threads.
MAKING RUBBER WARPS
The machine used for making the warps, shown at Fig. 3, is mounted on an
iron frame A, which carries the power driven warp beam B. Behind this is
an open top expansion reed C, the dents of which are regulated to open,
coarse or fine by an internal spring which is regulated by a hand wheel.
This reed also has a screw sidewise adjustment for centering. Behind the
reed C are fixed two pairs of nip rolls, D and E, and an open roller
F, which is followed by a belt-driven beater roll G, used to beat the
threads out straight as they leave the chain.
The rubber warp is first laid on a cloth on the floor, under the beater
roll. The end is then passed over the beater roll G, over the open roll
F, through the two pairs of nip rolls D and E, over the expansion reed C,
and then looped to a leader on the rubber beam, where the knot is put in
a counter-sink on the beam barrel, so as not to interfere with the lay
of the warp. The section of the warp between the two pairs of nip rolls
is brought down in loop form, shown at H, and the nip rolls are then
closed while the warp is in this position. The two sets of nip rolls are
speeded alike and the rubber is always kept slack between the gripping
points, so that all threads passing through the last set of nip rolls,
D, are perfectly gauged in length and tension when passing through the
reed C and on to the beam B. The threads of rubber are under considerable
tension, inasmuch as the beam B is driven faster than the nip rolls D and
E.
FRICTION LET-OFF
Where there is limited loom space, and where a small number of threads
are employed, as in the narrower garter fabrics, it is not as practical
to have the warps made mechanically, and for this reason they are not
likely to be put on the beams with as much uniformity of tension. In
such cases it becomes necessary to have some automatic device that will
correct any irregularities and maintain a uniform delivery throughout.
The device for doing this is shown at Fig. 4.
The warp carrier A is fastened to the back rail, which carries the warp,
over which is passed the friction cloth G which is hung from a rod D.
The friction cloth is fastened at the bottom to the graduated warp lever
E, which is bolted to the bottom rail H, as shown. The rubber threads
constituting the warp pass in a direct line to the harness C, and then
to the breast beam B. The lever E, and the weights F, allow for proper
adjustment of the friction cloth so as to keep the lever level as the
warp beam empties.
[Illustration: Fig. 3.—Rubber Warping Machine]
In making the rubber warps for narrow fabrics such as garters and
suspenders, where the last described method of warp delivery takes place,
it is customary to work from an entire sheet of rubber, splitting it up
into the required sections or strips of the various sizes called for in
the warps. This splitting and warping process must be done in a long room
where the warp can be stretched out to its full length, if possible,
after it is unchained. These warps are usually about 60 yards long. The
“head” of the sheet, or the part where the cutting knife has not gone
through, is spread out flat on a series of hooks at the beaming machine
and the tail end is fixed securely on a strong hook at the other end of
the room.
The requisite number of threads for the several warps which are to be
beamed are counted off and each different section is fastened to a beam.
The end knot is laid snugly in the counter-sink made in the beam barrel
for this purpose. A wide reed is used, covering the number of beams
operated in the machine, which is usually about four, and the threads are
reeded over spaces opposite the different beams. This reed can be moved
sidewise across the face of the beams and each warp properly centered so
as to keep the warp level. The operator then starts the beaming machine,
which may be operated either by hand or power, and the warps are wound
up. At the same time a helper walks towards the beamer carrying the tail
end of the warps and keeping the tension as nearly uniform as possible.
When the warps are all wound on the several beams, a lease is taken
in each of them in the ordinary manner, and each separate section is
securely fastened.
[Illustration: Fig. 4.—Automatic Friction Let-Off for Rubber Warps]
Should floor space be limited, a horizontal reel is used, which is about
six feet long and about five feet in diameter. On this the sheet of
rubber is wound after being split in proper sections at the head end and
divided by a coarse reed, so as to be able to distribute the different
sections all across the reel. Each section can then be taken off the reel
as required for the beams. The tension of the threads is governed by a
weighted leather strap passed over the face of the reel.