Silk fabric mechanical finishing equipment-drying equipment

Silk fabric mechanical finishing equipment-drying equipment

After the fabric is dehydrated, there is still bound water adsorbed by the fibers, which must be removed by drying and vaporizing with heat.
Drying equipment used in the dyeing and finishing production process can be divided into three types: drum dryer, hot air dryer and infrared dryer. Silk fabric is relatively soft and cannot withstand excessive tension. It should not be dried too quickly or excessively. Currently, two types of drum dryers and hot air dryers are commonly used in silk dyeing and finishing factories.
　(1) Roller finishing machine: The single-roller finishing machine is a contact dryer and consists of a frame, a drying cylinder, a telescopic expansion roller and a transmission device, as shown in Figure 10-26.

This machine mainly uses an iron or stainless steel roller, which is heated by steam to dry the fabric. The steam pressure of the drying cylinder is 0.20~0.30MPa, and the vehicle speed is 25m/min. The fabric is rolled into a roll and heated under tension through the surface of a heated roller. Since the fabric is in direct contact with the steam-heated metal roller and is subject to the pressure of the upper pressure roller, the fabric is ironed while drying. Some factories call the single-roller finishing machine a flat finisher. This is the reason. Another feature of this machine is that there is a stretching roller at each entrance and exit part of the fabric. The stretching force is very strong. The wetter the fabric, the tighter the warp direction, the greater the stretching effect. It is usually used in factories without tenter equipment. This machine is used for both drying and width shaping. Some factories also install a vacuum water suction machine in front of the machine to improve drying efficiency.
The single-roller finishing machine is the main drying equipment for silk printing and dyeing products. It has a simple structure, a small footprint, and is easy to operate. The finished fabrics are flat and smooth. It is mainly suitable for thin fabrics such as electric spinning and foreign spinning. , and can be used in conjunction with other machinery. However, due to the tight finishing, the surface of the fabric and the roller are in repeated contact, which easily causes friction and a hard feel; the fabric is rolled under high tension in a hot and humid state, and the colored and all-over printed fabrics are prone to “loosening” print”.
In order to improve drying efficiency, some factories often connect two or three single-roller machines together, or build a multi-roller dryer, which can dry at one time. In order to improve the feel of the finished product, many silk dyeing and finishing factories combine a vacuum suction machine, two single-roller dryers and a small felt finishing machine to form a “three-in-one” felt finishing machine. However, because it is a tight finishing, it does not improve the quality of the finished product.
　(2) Hot air dryer: Hot air dryer uses hot air to transfer heat to dry fabrics to remove moisture. Depending on the state of the fabric in the drying room, hot air dryers come in various forms such as hanging type, rotary screen type, and air cushion type.
①Suspended hot air dryer: The suspended hot air dryer is a loose drying equipment. Its shape is a tall rectangular parallelepiped, which is surrounded by asbestos and iron plates for heat preservation. The body has four straight-standing dryers. The blower blows hot air from the top of the machine, and below the air outlet is a row of high-temperature-resistant cloth guide rollers for hanging silk. As shown in Figure 10-27.

When the fabric enters the drying room from the front and top of the machine, due to the direct speed difference between itself and the guide roller circulation chain, with the help of the fabric’s own weight and the wind force from the blower, a certain length is automatically formed between adjacent guide rollers. The cloth ring is suspended on the cloth guide roller and slowly moves to the exit of the drying room with the circulating chain. This equipment is divided into two types: long loop and short loop. In the short loop equipment, the fabric is supported by rotating guide rollers.
Short-ring hot air dryers are often double-layered, three-layered or five-layered. Heavy fabrics and fabrics that are difficult to loop generally use short loops; otherwise, use long loops. The length of the loop is achieved by adjusting the speed ratio between the incoming and outgoing cloth speed and the forward speed of the guide roller chain. The length of the loop is about 1.5 to 1.2m. The main features of this machine are loose drying, uniform drying, small fabric elongation and low shrinkage. However, the fabric after drying is not flat enough and needs further ironing. The hanging hot air dryer is suitable for drying general finished products and semi-finished products, especially for fabrics with concave and convex patterns and crepe fabrics. It should not be used for silk fabrics that require a flat surface.
② Rotary mesh and metal crawler mesh hot air dryers: Rotary mesh and metal crawler mesh hot air dryers are also loose drying equipment, as shown in Figure 10-28.

The rotary mesh dryer rolls the fabric into a shaft first, guides it onto rubber tracks, and spreads it flat without tension into the hot drying room. There are two large metal circular meshes inside the dryer, and the fabric is wrapped in Passing through the rotary screen, the hot air is blown into the rotary screen from the top and bottom. The inside of the rotary screen is sucked by a centrifugal fan to circulate the hot air through the fabric gaps, so the drying efficiency is higher and the silk surface is flatter.
The principle of the metal crawler mesh dryer is the same as that of the rotary mesh dryer, except that the metal rotary mesh is changed to metal crawlers. The fabric is spread flat on the crawler belt (no tension in the warp and weft directions) and enters the hot air room. The hot air flows from The top blows in, and the exhaust fan suctions under the crawler track, so that the fabric can be dried in a tension-free state. This equipment is very suitable for crepe and embossed fabrics. This machine has high drying efficiency, flat silk surface and strong adaptability. It is suitable for drying crepe and patterned fabrics.
③Loose tension-free air cushion drying machine: This machine is mainly composed of cloth feeding device, drying room, hot air circulation system, conveyor net, cloth dropping device, etc., as shown in Figure 10-29(a) Show. The open-width fabric is introduced from the cloth feeding frame, and the fabric is spread flat on the conveyor net through the feeding roller. There is a knob on the cloth feeding frame to adjust the amount of cloth feeding, so that the fabric can be fully fed in a loose manner. The conveyor net carries the fabric into the drying room.

There is a hot air circulation system in the hot air room. The staggered upper and lower air nozzles are fixed on the voltage stabilizing box to make the hot air ejected more evenly. The upper air nozzle sprays strong hot air, blowingThe fabric is pressed onto the conveyor net; the hot air ejected from the lower nozzle lifts the loose fabric away from the conveyor net, causing the dried fabric to move forward in a wave shape in the air cushion. The schematic diagram of the nozzle blowing air is shown in Figure 10-29(b). The fabric is then guided away from the equipment by the drop mechanism.
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