Different weft insertion systems
Introduction
Weaving machines are
classified into four groups according to their weft insertion systems;
shuttle, projectile, rapier and jet (i.e. air and water jet) looms. Of these
groups, the shuttle and projectile weft insertion systems have reached the term
of their economic life, because of their low weaving velocity. The water jet
weft insertion system does not have a wide application in practice, as it is
only suitable for yarns made of hydrophobic fibres. Rapier and air jet weft
insertion systems are commonly used for almost all kinds of fibres and yarns.
When air jet and rapier weft insertion systems are compared, it is apparent
that the rapier system has a lower velocity than air jet systems. The air jet
weaving system is commonly preferred due to its high production speed.
In air jet weaving, the weft yarn is
moved by the friction created by the high speed air flow. The forces which are
required to move and accelerate the weft yarn are produced by the air jet.
These forces have to be higher than the combination of the force of the inertia
and the resistance forces of the yarn bobbin and the reserve system. The
carrier and the resistive force characteristics are defined by the consideration
of weft yarn properties and physical properties of the air flow. Air velocity
and yarn structures have complex interrelations due to their properties, such
as turbulent and laminar air flow, constant yarn diameter, linear density (count)
and elasticity. Air flow is important to increase weft velocity and
productivity, and so it must always be controlled, due to the change in the
yarn count and the coefficient of twist. When the coefficient of twist
increases,
the weft velocity decreases. Also, when
the yarn count (tex) increases, the average velocity increases. Weft yarn
velocity for the Toyoda-type weaving machine has been studied by Hasegawa et
al. This velocity achieves a certain average value along the weft insertion. It
reaches constant speed at a certain time tp which is such a function of the
weft diameter, that due to the diameter increase tp also increases . The
insertion force at a constant diameter weft increases due to the increase in
air velocity. With the decrease in weft diameter, the insertion force also
decreases. For this reason, it was observed that the velocity of the weft yarn
has a smaller value.
Air Jet Weaving Systems
The working principles of air jet weaving machines are based on
carrying the yarn by the friction of the air jet. During the yarn’s forward
movement by the air in the sheds, the velocity of the weft yarn decreases
because of the decreasing pressure and the disturbance on the air flow
direction. The air jet must provide a constant speed to the weft yarn along the
weaving wideness. However, weft yarn of a certain mass is carried by a single
jet at a limited distance. That is why the relay nozzles are installed at
certain distances, in order to prevent a decrease in yarn velocity. These are
implemented on a movable hollow-needle or slay system. The basic function of
the main jet is to load the weft yarn into the shed, and then to carry it to
the first relay nozzle at a certain speed. The weft yarn suddenly reaches high
velocity by means of the main jet. To preserve weaving defects and asynchronous
beat-up movement, the weft yarn position and the instant velocity of the weft
yarn must be fully controlled during the weaving process. view of the air jet
and its control system is shown in Figures 1.
Weaving Range
|
This model air jet loom can weave various nature,
manmade, synthetic fiber and blended spinning fiber.
|
Characteristic
|
1、Suitable for high speed and large reed width
→ Use strong box wall board on both sides, beating supper by using rocking shaft mid-supporter. Wide weaving range and also make the small noise and less vibration at high-speed operation. → Rocking shaft is fullness steel which using min-support. This motion improves rigidity of the beating. They ensure smooth and powerful beating even at high speed. → The rush start system delivers high-power torque at starting, enabling increased beating power for first pick, eliminating stop marks, and contributing to high quality production. 2、Digitalized automatic control system → Computer controlling system：there is on i-board in the machine; it can display the loom data such as the running condition, weaving technology data and trouble reasons. All These information can be copied to other looms by memory . → Memory card: Through digital memory card or central computer, all electrical setting caneasiliy storage or transfer duplicate to other JA10 air jet looms. Electrical setting including: weft yarn colors, fabric structure, warp yarn tension, weft yarn density, etc. Software can be upgrading through memory card. → Humanized interface: Customer can choose Chinese or English operation interface. → Fast fabric drop: Use fast interlock locking apparatus, it is easy to change cloth roller, cloth rolling diameter can reach 600mm, and fabric also can be drop while air jet loom running. 3、Weft insertion system: → Adopts main nozzle & sub nozzle & profile reed. The solenoid valves were controlled by CPU, which ensures the even air pressure during the weft insertion. When in ultra-high speed or wide reeds, the customers can choose main nozzle & auxiliary nozzle insertion style. It can accelerate the weft yarns under law air pressure, so it avoids weft yarn hurt and keeps it running stably. → Sub-gas shielded close to sub nozzle, gas supply distance is short, more suitable for high speed and also power consumption. → Using two feelers, making detection or normal weft short or weft bend, as a matter of course, but they also detect filling blow-off or long weft, and never overlook any mis-insertion, the heads are dirt resistant, ensuring a high reliability. → Pulling nozzle: this nozzle can pull the weft from right side, and then decrease the sub-nozzle gas consumption. On the other hand, this nozzle also can prevent the weft relaxing when weaving continuous filament. → New weft-brake device: this device decreases the peak tension, and avoid the breaking and loosing of weft. → Vibration model pooling system: ensure the accumulator release the weft smoothly when the loom is weaving fibrous yarn and wool yarn. 4、Widely shedding system → Completely modularized design, customers can choose various shedding device according to different requirement.? Crank shedding for plain fabrics: max. 6 heald frames; Cam shedding device for plain, twill and satin fabrics: max. 10 heald frames; Positive or negative electronic dobby, wide weaving range, computer controls the fabric design changing: max. 16 heald frames. 5、Excellent anti-stop-mark system: → Main motor start mode options: the rush start system delivers high-power torque at starting, enabling increased beating power for first pick, eliminating stop marks, and contributing to high quality production. → Cloth-fell auto adjustment: warp let-off immediately once loom stops, avoid the reed which is slowly reversing touch the cloth-fell, and debar the occasion for stop mark. When restart, it comes back to the tension set before and insert at normal cloth-fell. → Options for Stop-angle and Start-angle：The stop & start angle can be set freely according to different fabric and stop marks. → Adjustment for let-off capacity: The let-off capacity can be set freely according to different stop reason and stop time, this can prevent stop marks. → One-off insertion: no need beat when restart, directly insert weft, this can prevent stop bar on heavy twill fabrics. 6、Stable cloth-fell → Adopts top-mounted temple which increases the advance acclivitous angle for weaving and guide bar which is arranged close to the cloth-fell, therefore, all the double fabrics, triplet fabric, jacquard fabrics and high-density fabrics can get stable cloth-fell. 7、Compact and decent appearance → Professional design, compact and decent, operating easy. 8、Excellent performance with competitive price. |
SHUTTLELESS
LOOMS
·
The
fundamental principles of weaving are, SHEDDING i.e.
dividing the longitudinal threads
called 'warp' into two sheets;
PICKING i.e. insertion of transverse thread
called 'weft' into
the space created by the division of
warp sheets and BEATING
i.e. pulling the inserted wefts one
after the other to form
cloth. There is no change in these
principles whether it is
Handloom, Powerloom. Automatic Loom
or Shuttleless Loom
technology.
·
Shuttleless
looms have been developed to overcome the inherent
problems created by the dynamics of
the picking mechanism on
the conventional Fly Shuttle Looms
and make use of entirely
different methods of weft insertion.
Air Jet, Water Jet, Rapier,
Gripper (Projectile) and Multi-Phase
are the various types of
Shuttleless Weaving Machines named
after the method employed
for weft insertion.
·
Shuttleless
Weaving Machines are generally of wider widths
enabling the simultaneous weaving of
two or more widths; upto
400/420 cms. in the case of Air Jet
and Rapier and upto 540 cms.
in case of Gripper. The weft
insertion rates achieved are 1560,
1480, 2850 and 2565 Mtrs./Mt. for
Gripper, Rapier, Air Jet and
Water Jet Weaving Machines
respectively.
1.4 Shuttleless Weaving Machines are
sviitably designed to match the
requirements of high insertion rates,
shedding, beating and other
auxiliary motions. Let-off and
take-up mechanisms and weft
monitoring are invariably controlled
through microprocessors. The
machines are equipped with features
like automatic pick finding &
repairing.
Comparison of weft insertion systems
·
Projectile
Weaving Machines offered are upto 540 cms. width,
working at maximum insertion rates of
1560 mtrs/mt with 4 colour
pick sequence and with features like
automatic pick finding,
electronically controlled warp
let-off, weft accumulator and feeder,
electronically controlled lubrication
system and with a choice of
tuck-in, leno or fused selvedges.
Machine monitoring and controls
are aided by microcompressors to
improve efficiency, reduce
failures, simplify maintenance by
adjusting the operational status
of the machines during their
operation.
·
Similarly,
Rapier Machines are also available with similar elctronic
features. Machine design, material and
workmanship have been
perfected to make the Rapier a highly
versatile machine capable of
using the widest range of yarns and
weaving all types of fabrics.
·
With
the development of Air Jet technology, new models are offered
with maximum weft insertion rates of
2850 mtrs. per minute not
so far achieved on any other system of
Shuttleless Weaving
Machine, apart from multicolour weft
insertion upto 6 colours and
unusual electronic features like
bidirectional communication with
host computer, automatic pick
repairing, automatic controls on
weft insertion timings, looming robot
and automatic cloth doffing.
·
Water
Jet Machines continue to be offered in comparatively narrow
widths upto 230 cms. but with high
insertion rates of 2565 mtrs./
mt. maximum. The electronic monitoring
and control systems
available on other types of Shuttleless
Weaving Machines are also
available on Water Jet Machines.
·
Weft
Feeders have contributed in a big way to improve the
productivity of sophisticated weaving
machines. Feeders available
offer precise control of weft tension,
matching winding speed to the
varying speed of weaving machines, yarn
exhaustion and weft
breakage detection before the yarn has
left the spool.
·
Use
of electronics on Shuttleless Weaving Machines has not only
eased the operation of weavers but has
simplified supervision and
maintenance and also provided
integrated process automation.
Shuttleless Weaving Machines installed
in a shed can communicate
to a centralised data collection and
process monitoring system
and get feed-back for integrated
working to achieve maximum
corporate benefit. Systems are
available to load fabric designs onto
the jacquards equipped on looms, from a
central computer store.
Looms can be monitored for production
scheduling and necessary
instructions issued for changes.
Production Planning and Control
technique can be exercised on the
complete weaving shed through
such an integrated computerised control
system.
·
There
are about 40 well known manufacturers of Shuttleless
Weaving Machines mostly from Evirope and
Japan. Most of them
are offering more than one system.
However, Gripper (projectile)
System is offered by 4 manufacturers, the
most popular of them is
Sulzer of Switzerland. The features and
speeds offered by the
various manufacturers are more or less
comparable.and weft accumulators.
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