Detailed explanation of the commonly used drafting methods of spunbond nonwovens

Author: Date: 2019-12-31 07:50:55 Hits: 2167 spunbond nonwovens are based on the draft air flow means to achieve fiber drawing, drawing with different mechanisms applied, specific The drafting method also varies from model to model. In the spunbond system, the commonly used drafting methods mainly include wide-slit suction (negative pressure) drafting, wide-slit positive pressure drafting, and round tube drafting. 1. Wide slit suction (negative pressure) drafting. The characteristic of wide slit suction (negative pressure) drafting is the use of closed spinning drafting channels, air-laid, positive-pressure drafting airflow and cooling The air flow is combined into one, and the negative pressure generated by the suction device of the web forming machine accelerates the air flow and realizes the drafting of the fiber. Since the basic shape of the drafting channel is a tapered shape with a large upper and a smaller lower, the air flow in the channel is accelerated to realize the drafting of the fiber. The wide-slit suction drafting process is currently the most widely used process in the world. 2. Wide-slit positive pressure drafting. Wide-slit positive pressure drafting adopts an open spinning drafting channel, airflow (some models use static yarn separators) to form a net, and an integral independent drafter Using positive airflow as the drawing power, the spinning channel is fully open. The cooling airflow basically has no drafting function. Compressed air is generally used (the pressure is generally within 1Mpa) to achieve fiber drafting. According to the actual operation situation, the wide-slit positive pressure drafter has a higher drafting speed and better raw material adaptability, but due to the high outlet air velocity of the drafting device, the difficulty of controlling the uniformity of the web is increased. . 3. Round tube drafting. The tube drafting process is often abbreviated as 'tube drafting'. It adopts an open spinning drafting channel. Tubular (tube diameter is about 8-16mm, length can reach several meters) drafting device, using positive pressure airflow as drafting power. After the drafting airflow (compressed air) enters the annular space of the drafter, it is sprayed down from the diversion cavity into the drafting tube, and sprayed from the lower part. The high-speed airflow generates negative pressure at the inlet of the tow, and sucks the tow and ambient air into the tube. The tow is clamped and accelerated by the airflow in the channel to be drawn. In the tubular drafting system, the fiber drafting speed can reach 3000-5000m/min, so it can be used in both PP spinning systems and PET spinning systems that require higher drafting speeds. This round tube drafting method can achieve a higher drafting speed, the yarn speed can reach 5000～7000m/min, the drafting effect is ideal, and the drafting of the fiber is also relatively sufficient. It is currently used in the production of polyester nonwovens in China. The main process. Related tags: Previous: How to use non-woven fabrics in diapers and sanitary napkins-graphic details