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Excellent air-stretching equipment should be able to achieve the following functions: ①has the high-efficiency ability to adjust the stretching speed; ② can change according to the production process and variety changes; ③ energy saving; ④ the equipment is simple and easy to control; ⑤ helps fiber Evenly spread the net. Take this five points to take a look at our four current air stretching equipment.
The first is tube stretching. This method is the earliest stretching method of spunbonding. It originated from German Luqi Company. At present, there are more than 30 production lines using this method in China, which are composed of dozens of monofilaments. Stretched with compressed air in Ф10mm stainless steel pipe. An equipment with a width of 3.2mm is composed of dozens of small tubes. The advantage of this method is that it can make the fiber pulling speed reach about 5000m / min, but there are many disadvantages and the equipment structure is complex. For stainless steel pipes, there are a large number of metering pumps, spinnerets, melt valves, compressed air valves, and a large number of under-tube swing piece equipment that are suitable for it, and the energy consumption is also high. And the variety changes, the fiber web is not uniform enough. At present, the United States, Japan, and Germany have eliminated this type of tube stretching, and only Italy's STP and ORV are still using it. The relevant spunbond factories in China should also consider reforming this outdated old method, transforming their own stretching equipment, and improving the quality of spunbond fabrics.
Then there is the small slit stretching method, which started in Italy. W. Company T was later copied by many of our country. In this way, the fibers from multiple spinnerets diagonally arranged in a line were drawn into a small slit drafter for stretching. The structure of this equipment is also relatively complicated. There are many metering pumps, many melt valves, many spinnerets, many air pressure valves, many oscillating rollers, and uneven fiber formation. Its advantages are better lateral strength of the cloth and width of the cloth It can be adjusted to a narrow direction. In recent years, China has basically stopped manufacturing such equipment.
Long slit-type negative pressure stretching was first used in China from the introduction of Leifen equipment. In recent years, many places in China have produced similar equipment according to this principle. Its feature is that only a long spinneret is used. One or several metering pumps cover the drafter on the netting machine, and draw the air under the netting machine for stretching. The main advantage of this form is that there is only one spinneret, and the spinning box is much simpler and not much. The drafting pipeline eliminates the rocking method, so the uniformity of the cloth becomes better and the power consumption is the lowest. The disadvantage is that the stretching speed is relatively low and cannot be adjusted high, and the lateral tensile force of the spunbond fabric is low. In addition, its The equipment is all fixed on the steel platform and cannot change with the process and variety.
Long slit-type positive pressure stretching is a new type of method successfully developed in recent years. The equipment imported from Japan and the United States in the three plants of Liaohua, Zhangjiagang and Shaoxing in recent years was selected in this way, and the spinning method is also A long spinneret, one or several metering pumps, is relatively simple, especially its drawing equipment, which uses a long small box, the fiber passes through the middle gap, is drawn by compressed air, and this The drafting box can also change its position up and down according to different processes and varieties, and its drafting speed can reach 6000-8000m / min, which makes the first few stretchers out of reach. The biggest advantage of this kind of drafter is: drafting speed High, the equipment structure is relatively simple and easy to control, can adapt to a variety of different processes and varieties changes, the fiber is more uniform, is the current direction of airflow stretching equipment reform, its shortcomings are higher energy consumption and lower transverse tension of the cloth, Room for improvement.
Spunbond machinery-a method of reforming airflow stretching equipment
The fiber drawing of spunbond nonwoven fabric is drawn by air flow, which is different from the unique drawing method of chemical fiber filaments and is the heart of spunbond. At present, there are four ways of this kind of air-stretching in China, namely â‘ tubular stretching, such as polyester spunbond production line, STP production line and MODERN production line; â‘¡ narrow slit positive pressure stretching, such as NWT production line and Shenyang Early production lines of the Center, 606 Institute and Shanghai Synthetic Fiber Institute; â‘¢Long slit negative pressure production lines, such as Leifen type and recent Wenzhou Changlong company domestic production lines; â‘£Long slit positive pressure production lines, such as NKK, Nordson The company and Hongda Research Institute etc. These production methods can be used for normal production of spunbond fabrics, but their effect on the stretching effect and the uniformity of the finished cloth are different.