The spinning process of aramid staple fibers mainly includes the following steps:
Opening: Aramid fibers are prone to friction and static electricity during the spinning process, resulting in problems such as fiber floating and flying. In order to solve these problems, 2% antistatic agent can be added during the opening process, sprayed on the loose aramid fiber raw materials, and fully mixed and evenly stacked for more than 12 hours. The operating environment should be controlled at a humidity of 70-80% and a temperature ≥24 degrees Celsius.
Cleanup: Due to the high modulus and high strength of aramid fibers, the cleanup process needs to follow the principles of short process, less feeding, light beating, large spacing, and light quantity to reduce fiber damage. After the cotton rolls are rolled, they should be wrapped with plastic film to prevent the oil from volatilizing.
Combing: Combing is the most critical process in the aramid spinning process. Polyester card clothing is used to enlarge the spacing between the cylinder and the cover plate to reduce the possibility of static electricity generated by the friction between the fiber and the card clothing causing winding of the cylinder. In actual production, the process principle of low speed, light weight and large gauge is adopted. The main process parameters include cylinder speed of 300 rpm, doffer speed of 25 rpm, licker-in speed of 645 rpm, operating environment temperature greater than 24℃, and humidity of 80-90%.
Drawing: The drawing process adopts the process principle of slow speed, large gauge, heavy pressure and smooth drafting. Use anti-static rubber rollers to clean the veil channel in time. Specific parameters such as 8 strands and 1 strand, 25 grams/m, 180 m/min, and 11% moisture regain; 10 strands and 1 strand, 16 grams/5 m, 180 m/min, and 10% moisture regain; 8 strands and 1 strand, 15 grams/5 m, 180 m/min, and 10% moisture regain.
Roving: The roving process adopts the process principle of slow speed, heavy pressure, larger back zone gauge and smaller draft multiple. Appropriately increase the twist coefficient of roving. Specific parameters include roving dry weight 4 g/10 m, roller pressure 15 daN/double spindle, gauge block specification, spindle speed 500 rpm.
Spinning: The spinning process needs to control the spinning tension to ensure the quality of the yarn. Specific parameters include spindle speed 7500 rpm, front roller speed 30 m/min.
Steaming: Steaming is to eliminate the stress inside the yarn and improve the uniformity and strength of the yarn. Specific parameters include steaming temperature 100℃, time 30 minutes.
Self-winding: Self-winding is to wind the yarn into a bobbin shape for subsequent processing. Specific parameters include bobbin diameter 30 cm, bobbin length 1000 m.
Double-threading: Double-threading is to combine two or more single yarns into one yarn to improve the strength and uniformity of the yarn. Specific parameters include double-threading speed 300 m/min.
Twist twice: Twist twice is to increase the twist of the yarn, improve the stability and strength of the yarn. Specific parameters include twist speed of 3000 rpm.
Finished yarn: After the above processes, the finished aramid staple yarn is obtained
