There are many classifications of looms. According to the weft insertion method of weaving, they can be divided into shuttle looms and shuttleless looms.
The weft insertion of shuttle loom is a loom that uses traditional wooden shuttle or plastic shuttle for weft insertion. Due to the large size and heavy weight of the shuttle, the shuttle is repeatedly projected back and forth, causing the machine to vibrate loudly, produce high noise, high energy consumption, slow speed, and low efficiency.
There are also various weft insertion methods for shuttleless looms, including rapier, air jet, water jet, projectile and multi-shed (multi-phase) methods.
Today we will talk about air jet looms among shuttleless looms
Air jet loom
The air-jet loom is a new type of loom that uses the high-speed airflow generated by the release of compressed air to pull the weft yarn through the cloth fell to complete the weft insertion. It is currently the fastest growing type of shuttleless loom.
1. Historical development
1949
Czechoslovakia first made an air-jet loom. Due to the lack of control measures for the spread of airflow, the width of the woven fabric was only 45cm.
1956
The combined duct piece was developed to limit the diffusion of air flow, making a breakthrough in jet technology.
1963
The Netherlands has developed auxiliary nozzle weft insertion technology, which greatly increases the width and loom speed.
1970s
The advent of special-shaped buckles, a new form of restricting airflow diffusion, has brought new progress in the range and quality of fabrics woven by air-jet looms.
recent years
The new development trends of air-jet looms are energy saving, intelligence, networking, expanded variety adaptability, high speed and low vibration, etc.
2. Principle of weft insertion
Air-jet weft insertion uses air as the weft insertion medium, and uses the jetted compressed airflow to produce frictional traction on the weft yarn, bringing the weft yarn through the shed, and achieving the purpose of weft insertion through the jet generated by the air-jet.
Characteristics of jet weft insertion
The characteristics of air-jet weft insertion are high speed, large tension, small shed, and relatively high requirements for raw yarn and semi-finished products.
Air-jet weft insertion is a passive weft insertion method. When the weft yarn jumps over the shed, the tension is small and there is no control. Therefore, it lacks sufficient traction for weft yarns with high linear density or fancy yarns. At the same time, the warp opening state has a great influence on the quality of weft insertion, and it is easy to produce fabric defects such as weft shrinkage and weft foldback.
3. Main structure and characteristics
The air-jet loom mainly consists of a frame, a transmission and braking system, a shedding mechanism, a weft insertion mechanism, a beating-up mechanism, a let-off mechanism, a take-up mechanism, an edge-twisting mechanism, a scissors mechanism, an edge yarn catching device, a centralized oil supply and an automatic Control system and other components.
The main structural and technical characteristics of air-jet looms:
1. Weft insertion method: Under the action of the main and auxiliary nozzles and special-shaped reeds, the high-speed airflow generated by the release of compressed air is used to pull the weft yarn through the fabric fell to complete the weft insertion. to
2. Opening methods include crank opening, cam opening, dobby opening and jacquard opening, which can be selected according to the fabric weave. The general conventional configuration is a cam opening.
3. There are three types of beat-up methods: four-link beat-up, six-link beat-up and conjugate cam beat-up.
4. The warp let-off mechanism mainly adopts electronic semi-active and semi-passive continuous let-off and mechanical semi-active and semi-passive continuous let-off.
5. The coiling mechanism includes mechanical continuous coiling and electric coiling. Domestic air-jet looms are generally equipped with mechanical continuous take-up.
6. Cloth rolling: Generally, the cloth is rolled inside the machine, and the cloth rolling outside the machine is optional.
7. Rack: Japanese models use box-type wall panel racks, while European models mostly use panel-type wall panel racks. Both types of frames exist in domestic air-jet looms.
8. Transmission and braking: Reluctance motor direct transmission and braking, with stepless speed regulation; super-start motor transmission, electromagnetic brake braking; ordinary motor and flywheel and clutch transmission, electromagnetic brake braking. to
9. Lubrication: The main transmission part adopts oil bath lubrication, and other parts adopt oil cup lubrication or centralized oil supply.
10. Yarn supply: A floor-standing yarn supply rack is installed outside the machine, which can be equipped with 2 packages, 4 packages, 6 packages or 8 packages.
11. Length measurement and weft storage: The electric drum stores the weft, and the drum diameter and yarn stop pin are fixed in length. to
12. The edge-twisting mechanism includes planetary edge-twisting, leno edge-twisting, electronic edge-twisting, fold-in edge and hot-melt edge-twisting. Choose according to fabric requirements.
13. There are two types of fabric edge: raw edge and smooth edge. Depends on the institution chosen. to
14. Ring temple support. Choose the number of loops and needle size according to the fabric. to
15. Weft cutting includes mechanical scissors and electronic scissors.
16. Weft detection Photoelectric weft finder. Divided into reflective and transmissive types.
17. Weft stopping device By TanThe weft detector detects the flight status of the weft yarn, and determines whether the flight is normal or not through the weft detection control unit and issues an instruction to stop or continue running.
18. The stop device includes an electrical contact rod stop rack type stop device, a far-infrared detection stop device and a comb-type stop device. At present, the warp-stop type is mostly used, and 4, 6 or 8 rows can be used according to the warp density.
19. Display keyboard display (parameter setting, loom status monitoring, self-diagnosis of faults); multi-color indicator lights indicate warp stop, weft stop, waiting and other information. to
20. Accessory devices: auxiliary main spray, drafting spray, weft braking device, etc.
21. The control system uses a microcomputer as the control core to control weft insertion, weft selection, weft storage, warp let-off and loom action respectively, and set the weaving process parameters (warp tension, color, solenoid valve opening and closing time, etc.) on the keyboard. . Each control unit controls the corresponding actions. There is an operation button board on the left, right or in the middle of the front of the loom to facilitate the operator’s operation.
4. Scope of application and fabric varieties
The early air-jet looms had a small adaptability range and were mainly used to produce white gray fabrics. The fabric width was small, the speed was slow, the fabrics had great limitations, and the fabric quality was not high. However, starting from the early 1980s, with the development of special-shaped reed and relay weft insertion technology of air-jet looms, as well as the application of electronic computers, sensors and frequency conversion speed regulation technology, the speed of air-jet looms and the automatic monitoring of looms have been greatly improved. level, especially the rapid development of air-jet looms in the past 10 years, which has enabled air-jet looms to have many advantages such as high quality, high speed, high output, high automatic control level, etc., and the range of varieties has been greatly improved.
The width of the air-jet loom has increased from 190cm and 280cm to more than 340cm, 360cm and 400cm; the main nozzle has been increased from single nozzle to double nozzle and four nozzle; the multi-color weft insertion system controlled by computer software can carry out 4-color to Weft selection in 12 colors; weft yarn raw materials can be chemical fiber filament, chemical fiber staple fiber, pure cotton yarn, wool yarn, glass fiber yarn, various fancy yarns, etc.; product varieties range from high-count, fine, thin, high-end fabrics to thick-count, high-density fabrics Both thick and thick fabrics can be produced, and Dornier air jet looms have been used to produce industrial fabrics such as filter fabrics, abrasive twill fabrics, steamed fabrics and fiberglass wall coverings. The new air-jet looms of Belgium’s Picano and Japan’s Tsudakoma are also equipped with electronic jacquard, dobby and other shedding systems to adapt to the production of multiple types of fabrics.
5. Comparison with other shuttleless looms
rapier loom
Rapier looms have unique advantages in variety adaptability, but the weft insertion rate is lower than that of air-jet looms, only 1400m/min, which is about 50% of that of air-jet looms; the yarn recovery rate is higher than other shuttleless looms. At present, rapier looms are mainly used for the production of small batches and various weft yarn fabrics such as decorative items.
Projectile loom
Projectile looms have advantages in weaving extra-wide fabrics and high-end decorative fabrics, but the weft entry is lower than that of air-jet looms, which is 1200m/min; the energy consumption for projectile acceleration only accounts for 15%, and the energy consumption is unreasonable; The material performance and mechanical weaving accuracy of the shuttle torsion shaft are relatively high; the price is expensive and the one-time investment cost is large.
water jet loom
Water-jet looms have limitations in weaving quality and are only suitable for weaving hydrophobic yarns such as synthetic fibers and glass fibers. Relevant components on the loom should be made of stainless steel.
polyphase loom
Polyphase looms can weave at extremely high pick rates. But it can only produce simple ordinary fabrics, and the power consumption per square meter of fabric is higher than other shuttleless looms.
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