Spinning machine transforms semi-finished roving or sliver into spun yarn by drawing, twisting and winding, which is the main machine of spinning. The production quantity and quality of spun yarn is the comprehensive reflection of the spinning process.
The production unit of spinning machine is spindle, and the production (kilogram) of per-thousand spindle and per-hour is often used to measure the production level of spinning machine. The production scale of spinning factory is always expressed by the total number of spindles and the yarn on each spindle is often broken due to various reasons, therefore, the breakage rate is often expressed by the number of broken ends in per-thousand spindles per-hour, which affects labor productivity, equipment productivity, spinning quality and dust content in the workshop. Spinning machine is the most energy-consuming machine in spinning production. During the production process, when a roll is finished (Pipe yarn), it will stop production, and then the yarn can be continued after the roll is replaced by an empty one. Therefore, the size of the roll also affects labor productivity, equipment productivity, and energy consumption.
The spindle speed, roll and breakage rate are interrelated and restrict each other, which is the symbol of the spinning technical level, and should be considered comprehensively from the aspects of society, technology and economy, so as to determine a more appropriate value.
Ⅱ. Process Requirements
Spinning is the last process in spinning production and the breakage rate of spinning is the key to affect product quality, output and energy consumption. The essence of spinning broken ends is that the strength of yarns between roller and guide hook is less than the tension of spinning section. So the spinning tension must be stabilized to reduce the breakage rate of yarn.
Spinning winding at high speed forms balloons. The fluctuation of balloons at different spinning stages affects the value of spinning tension, which is the direct factor that causes breakage rate. Finding out the tension change characteristics of balloons in doffing is very important to control a steady tension and reduce the breakage rate.
1.The relationship between the spinning tension and spindle speed: there is a parabolic relationship between the tension and speed, that is, the spinning tension increases with the increase of spindle speed, and when the spindle speed is higher, the spinning tension increases even more.
2.The spinning tension change in doffing: at the beginning of spinning, the yarn tension reaches max value, because of the longest balloons and smaller winding diameter. With the rising of the steel plate, the balloon tension gets less, but the maximum balloon appears before and after the forming of pipe bottom,and the tension is the most unstable at this time, resulting in the instability of steel ring movement. After the forming of pipe bottom, the change of winding diameter plays a major role in the yarn tension. When the steel plate position is rising (small diameter), the spinning tension is large, and balloons shape is small.
When the steel plate is positioned at the bottom (large diameter), the spinning tension is small and balloons shape is large. Spinning tension and balloons shape reach the most stable at middle yarn stage. Before the full yarn, the balloons shape is flat, but the spinning tension has a sharp recovery phenomenon when the height is too high, and it will lose the regulating effect on the tension, so that the tension is unstable. When the yarn winding rises and falls in short range each time, which rises slowly and falls fast, and if it is measured by the tension meter, the peak value of tension changes sharply when the steel plate turns from top to bottom. At this time, the balloons shape change is also very large which causes the breakage and irregularity of the twist.
Ⅲ. Solution of VEICHI Products
After the installation of VEICHI AC80C, the spinning speed should be reduced by 5% ~ 8% in small yarn and big yarn spinning (aiming to reduce the breaking rate). And the spinning speed should be increased by 5% ~ 15% for the middle yarn according to the on-site conditions. Considering the length of middle yarn is 80% of the whole length of yarn, the overall speed of spinning is increased by nearly 10%, greatly improving the effective operation time of spindle and improving the spinning production efficiency , and thus the production is also increased by nearly 10%.
The high efficiency spinning system with VEICHI inverter could achieve steady and reliable operation, and gain high economic benefits for customers. And VEICHI overall solution is highly praised by customers through the actual production test. The specific advantages are as below:
1. Increase the volume of production;
2. Improve the quality and reduce the breakage rate;
3. Save materials and electric energy;
4. Improve production efficiency;
5. Extend the service life of machine;
6. Reduce maintenance workload.