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The shrinkage of nylon monofilament is proportional to the temperature of the hot box

An important factor affecting the elasticity of the nylon-spandex air-coated yarn is the stretch ratio of the spandex yarn. When the same spandex is used, the elasticity of the nylon-spandex air-coated yarn increases with the increase of the spandex draw ratio. However, due to the general heat resistance of spandex, downstream customers still have heat treatment processes such as printing, dyeing, and molding. If the stretch ratio is too high, it is easy to cause the spandex to break, resulting in horizontal lines or defects on the fabric surface. According to the customer's requirements for product elasticity, combined with the physical properties of spandex, the author sets the spandex stretch ratio to 3.3 times.​​

D/Y ratio refers to the ratio of friction linear speed to output roller W2 linear speed. If D/Y is too large or too small, it is easy to cause the nylon monofilament to become entangled or stiff, which will affect the air coating effect of the network device. Therefore, choosing an appropriate D/Y ratio is also one of the key points to ensure network degree.​​

Hot box temperature.​​

Relevant data show that the crimpability of nylon monofilament is proportional to the temperature of the hot box. When the process conditions such as the speed and the draw ratio of the nylon monofilament remain unchanged, the crimp rate and crimp stability of the nylon yarn increase with the increase of the hot box temperature, which affects the elasticity of the coated yarn. However, if the temperature is too high, it will produce melting tight spots, which will affect the air coating effect of the network device. After the comparative test, when the processing speed is 720m/min and the hot box temperature is 170c, the nylon monofilament can maintain good elasticity and curling.​​

Feeding angle to overfeeding ratio.​​

The installation position of the network device directly affects the feeding angle of the ammonia-coated silk. The feeding angle is the angle between the yarn before entering the networker and the network channel. According to experience, when the feeding angle of nylon monofilament and spandex yarn is 15~25°, the network effect is better.​​

The overfeed ratio (W1/W2) refers to the speed ratio between the second roller and the auxiliary roller, which directly affects the tension of the tow. Within a certain range, the larger the overfeed ratio, the smaller the tension of the tow, the easier the monofilament is to make saddle motion through the netting device, and the netting degree will increase. However, the overfeed ratio is to a certain extent, and the monofilament is easy to float out of the top roller, resulting in breakage.​​

Therefore, when the feeding angle is 25° and the overfeed ratio (W/W2) is 1.080, the coated silk product has a good network effect.​​

Web Nozzle and Web Pressure.​​

The network effect that affects the quality of gold-ammonia air-coated filaments mainly depends on the structure of the network nozzle [71. At present, domestic and foreign markets. There are many forms of network nozzles, including round, V-shaped and so on. Different forms of nozzles have a great influence on the quality difference of the air-coated wire mesh, among which the double circular and V-shaped nozzles have a good network effect. In addition, the hole type, hole diameter and length ratio of the networker will also affect the network effect. The circular nozzle is especially suitable for high-speed network, so the author chose the high-speed network nozzle with 1.1mm aperture.​​

Another important factor that affects the quality of Jin ammonia air-coated silk is network pressure. Compressed air has a large impact on the air packaging process. Through experiments, it is found that when the compressed air pressure is 0.05mpa, the tow is still in a loose state, and the monofilament can only be loose and cannot be connected. When the pressure reaches 0.10mpa, the exchange between nylon and spandex begins to form, but the network degree and network fastness are low. With the continuous increase of pressure, when it reaches more than 0.15mpa, the compressed air has enough energy to drive the monofilament, and form a network point after blowing the loose filament. With the increase of pressure, the gas injection speed also increases accordingly, the degree of network also increases accordingly, the distribution of network points tends to be uniform, and the tightness of the exchange point changes with the change of air pressure and the change of the degree of exchange. But when the degree of network reaches a certain value, the pressure increases again, and the degree of network no longer increases significantly, because the pressure is too large, and part of the kinetic energy forms a useless eddy current outside the wire.
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