Working Principle Of Air Jet Loom
Air jet weaving machines were invented in Czechoslovakia and later refined by the Swiss, Dutch, and Japanese were designed to retain the tension less aspect of the picking action of the water jet while eliminating the problems caused by the use of water.
Air Jet Loom:
The air jet weaving machine combines high performance with low manufacturing requirements. It has an extremely high insertion rate. Due to its exceptional performance, air jet machines are used primarily for the economical production of standard fabrics, covering a wide range of styles. Meanwhile, more and more niches and special fabric segments are covered; heavy cotton fabrics such as denim, terry fabrics, glass fabrics, etc.
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| Air Jet Weaving Machine |
Main Parts of Air Jet Loom for Weft Insertion:
1) TENSIONER: Additive disk type tensioner is used for weft insertion which maintain proper tension in the weft yarn.
2) WEFT BREAK SENSOR: It is an electric sensor which detect any weft break in the region between weft package and accumulator and automatically stop the loom in case any weft break.
3) ACCUMULATOR: It is adevice which fitted between weft package and main nozzle that unwinds a predetermined length of weft from the package and store it in the form of no. of coils on a cylindrical drum. This yarn then fed in to insertion device.
4) STOPPER: It is an electronically controlled electromagnetic device integrated along with the accumulator. Its function in releasing the yarn at starts of insertion and stop it at the end of insertion.
5) BALLOON BREAKER: It is fitted just after accumulator, its function is to separate the balloon formation. So as to reduce as ballooning tension as well as minimize the tension fluctuation. It is generally used for coarser yarn.
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6) FIXED MAIN NOZZLE: Its function is to form the air jet from compressed air with the required velocity and acceleration characteristics and project it in a proper direction in to air guide channel.
7) RELAY NOZZLE OR SUB NOZZLE: Fitted in series along the sley. It creates an additional air flow in the direction of air jet. So as to comensate the loss of air velocity.
8) PROFILE REED: Here the reed is profiled. So as to form a guide channel which guide the air jet as well as weft during insertion.
9) WEFT CUTTER: It is cam operated device fitted in the region between the moveable main nozzle and the reed at picking side. Its function is to gripping and cutting the weft after every pick at around beat-up.
10) AIR GUIDE CHANNEL: It is formed on the reed. Its function is guiding and confining the free expansion of the air jet in order to maintain the velocity over larger distance as possible.
11) WEFT DETECTOR: It is an optical device fitted at the end of reed at the receiving side. Its function is to check the arrival of weft at the receiving side .In case of late arrival or miss pick, then it sense and automatically stopped the loom.
12) STRETCH NOZZLE: Located just beside the weft detector .It supplement the effect of enhanced stretching action on the weft by the closely spaced relay nozzle at the end of insert ion. So as to prevent the chance of weft recoiling due to action of stopper.
13) SELVEDGE CUTTER: Located at the receiving side. It is an electronically operated mechanical device which cut the weft yarn extending between fabric and auxiliary selvedge .So as to separate the auxiliary selvedge which is passed out as a waste.
The yarn is pulled from the supply package at a constant speed, which is regulated by the rollers, located with the measuring disk just in front of the yarn package. The measuring disk removes a length of yarn appropriate to the width of the fabric being woven. A clamp holds the yarn in an insertion storage area, where an auxiliary air nozzle forms it into the shape of a hairpin.
The main nozzle begins blowing air so that the yarn is set in motion as soon as clamp opens. The hairpin shape is stretched out as the yarn is blown into the guiding channel of the reed with the shed open. The yarn is carried through the shed by the air currents emitted by the relay nozzles along the channel. The initial propulsive force is provided by a main nozzle. Electronically controlled relay nozzles provide additional booster jets to carry the yarn across the shed. The maximum effective width for air-jet weaving machines is about 355 cm. At the end of the each insertion cycle the clamp closes; the yarn is beaten in, and then cut, after the shed is closed. Again some selvage-forming device is required to provide stability to the edges of the fabric.
These weaving machines use a jet of air to propel the weft yarn through the shed at rates of up to 600 ppm. Date from manufacturers indicate that air-jet looms operate at speed up to 2200 meters of pick inserted per minute. They can weave multicolored yarns to make plaids and are available with both dobby and jacquard patterning mechanism.
Air jet weaving is more popular because the machines cost less to purchase, install, operate, and maintain than rapier or projectile weaving machines, and the air jet can be used on a broader variety of yarns than a water jet.
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