一．Spinning process flow
The conventional melt spinning process is as follows: dry slicing → melt extrusion → mixing → metering → filtration → spinning → cooling and forming → oiling → winding → UDY tube
二. Due to impurities in the melt, filtration is required before spinning. We usually use Candle Filter, Metal Sand, Leaf Disc Filter, Spin Pack Filter, and other filtering materials to filter the melt. The specific and detailed steps of spinning are as follows:
1.Melt extrusion
Slices enter the screw extruder from the feed inlet by their own weight. Due to the rotation of the screw, the slice moves forward along the screw groove. A heating element is installed on the outer side of the screw sleeve, which transfers heat to the slice through the sleeve. At the same time, the friction and compression of the slices inside the screw extruder also generate a certain amount of heat. Slices are melted by heat and compressed by an extruder, resulting in a certain melt pressure.
2.Mixing
It refers to the use of a static mixer to evenly mix the molten material at the screw outlet. This is not an essential step, but using a static mixer for mixing can achieve the goal of strengthening the uniformity of the molten material, while reducing the temperature and residence time difference between the pipe wall and the pipe center when the molten material passes through the bent pipe.
3.Measurement
The molten material output by the screw extruder is distributed by the distribution pipe to the metering pumps at each spinning site for metering, to ensure uniform filament size. The metering pump can also increase the pressure of the melt to meet the needs of high-pressure spinning.
4.Filtering
Before spinning, the melt must be filtered using Metal Sand, Candle Filter, Leaf Disc Filter, Spin Pack Filter and other filtering materials to remove impurities. In high-pressure spinning, the filter layer can also generate high resistance, causing the melt to generate heat through friction, increase temperature, and improve the rheological properties of the melt.
5.Spinning
The melt is filtered and evenly distributed by the distribution plate to each nozzle hole on the spinning plate, and is ejected from the nozzle hole to form a fine flow of the melt.
6.Cooling forming
The process in which a molten stream is cooled by a cooling medium and solidifies into a filament is called cooling forming. During cooling, due to the stretching effect of the spinneret, the fine flow of the melt gradually refines before solidification. Cooling and forming are completed inside the spinning window. The cooling air forced out by the blowing window at the upper end of the spinning tunnel can ensure uniform cooling conditions. The forming conditions have a significant impact on the performance of the filament.
7.Oiling
Conventional spinning uses oil tanker loading. The cooled and formed wire passes through a channel to reach the winding machine and comes into contact with the oil tanker, completing the oiling process.
8.Winding
After changing the direction and adjusting the tension of the oil containing wire rod through the upper and lower guide disks, it is wound on the tube through the transverse guide wire device. The friction rollers on the tube and winding head come into contact with a certain pressure and maintain the same linear velocity through friction transmission. This speed is usually referred to as spinning speed.
Post time: Nov-13-2024