The main advantage of the application of frequency conversion transformation of spinning frame is that it can realize automatic stepless speed change according to the change law of large, medium and small yarn tension of doffing, and optimize spinning conditions, so as to maintain the tension stability in each stage of spinning as much as possible. It will play a positive role in further reducing broken ends, reducing hairiness, achieving high quality and high yield, reducing energy consumption and reducing labor intensity of lathe workers.
Characteristics of tension variation of spinning frame
Spinning is the last working procedure in spinning process. In spinning production, spinning end breakage is the key to affect product quality, output and energy consumption. The essence of spinning end breakage is: when the strength of the yarn from roller to guide hook is less than the tension of spinning section, yarn breakage occurs. Therefore, to reduce yarn breakage, it is necessary to stabilize spinning tension.
The air ring is formed by spinning at high speed. The fluctuation of air ring in different spinning stages affects the spinning tension, which is the direct factor of the number of broken ends. It is very important to make clear the change characteristics of balloon tension in one doffing to control the spinning tension to change smoothly and reduce the breakage.
(1) The relationship between spinning tension and spindle speed: the relationship between spinning tension and spindle speed is parabola, that is, when the spindle speed increases, the spinning tension increases with the increase of spindle speed, and the higher the spindle speed, the greater the increase of spinning tension.
(2) The change of spinning tension in a doffing process: when the empty tube is spun at the beginning, the spinning tension is large because of the long balloon and the smaller winding diameter. With the rise of the ring plate, the tension of the balloon decreases, but before and after the forming of the pipe bottom, the balloon bulge is large, and the tension is unstable, resulting in the unstable movement of the steel coil. After the tube bottom is formed, the change of winding diameter plays an important role in the yarn tension. When the position of the steel ring plate rises (at the small diameter), the spinning tension is large and the balloon convex is small. When the ring plate is located at the bottom (large diameter), the spinning tension is small and the balloon bulge is large. The spinning tension and balloon shape are stable in the middle spinning stage. However, when the height is too small, the spinning tension rises sharply, and the tension is unstable due to the loss of the adjustment of the tension. Each time the yarn is winded, it will rise and fall slowly and fall quickly. The results show that the peak value of tension changes suddenly when the ring plate turns from top to bottom. At this time, the shape of balloon changes greatly, which is easy to cause breakage and uneven transmission of twist.
Investment and return
1. The effect of increasing yield
The spinning frame installed with Tianlang Weichuang series frequency converter should reduce the speed of small yarn and large yarn by 5% ～ 8% (the purpose is to reduce the breakage rate), and increase the speed by 5% ～ 15% according to the vehicle conditions. The length of the middle yarn accounts for 80% of the whole spinning length, that is, the whole spinning speed is increased by nearly 10%, which greatly improves the effective operation time of the spindle and the spinning frame The production efficiency and output increased by nearly 10%.
2. Improve the quality and reduce the rate of broken head
Yarn breakage is the main harm in spinning production: it affects the output of spinning frame and reduces the production efficiency; it increases the labor intensity of the car stopper; it is easy to cause the increase of fabric defects, causing a large range of quality fluctuation; it increases the consumption of back flowers, silk reels and machine materials; therefore, the end breakage is the obstacle to the development of spinning production with high yield, high quality, low consumption and large package.
And ingot speed. With the increase of spinning speed, the broken ends will increase. When the spindle rotates at constant speed (without frequency conversion), the distribution of doffing broken ends is as follows: more small yarns, less large yarns, and small medium yarns, with the ratio of 5:3:2. Using frequency converter to adjust the speed, the yarn breakage can be reduced by about 10%.
Due to the reduction of broken ends, the stop man can use the saved time to do cleaning work, reduce many sudden yarn defects and ensure the yarn quality.
3. Saving raw materials and electric energy
For some difficult varieties, such as strong twist yarn, core spun yarn, hemp cotton yarn and high-grade combed products, the unit yield can be greatly increased by selecting the better points in the production process by changing the speed, and the unit area yield can be greatly increased, the back joint, the return flower and the roller pattern will be reduced correspondingly, that is to say, the raw materials for rework can be saved.
The main power factor of the motor can be improved by using the frequency converter. Without frequency conversion, the active power of general spinning frame is between 7.3-8.1, and after frequency conversion, the active power reaches more than 9.9, which reduces reactive current, reduces line loss, saves electric energy, and reduces equipment power consumption under the same output.
Energy saving example: let's take a series of data to analyze. The price of a 15kw inverter is 5000 yuan, and the average life is 6 years. If the average maintenance cost is 1200 yuan after the warranty period, the average power consumption is 0.6 yuan. Originally, each 15kw motor runs for 1 hour at 8 yuan, 192 yuan a day. After using the frequency converter, the measured current is reduced by 33.6%. Because most of the current is reactive, the auxiliary power meter is active power meter. According to the normal condition, 13.6% of the active power meter is saved, and the remaining 20% is saved in the high voltage. Taking 13.6% as an example, 26.11 yuan can be saved in one day, and 7833 yuan of electricity can be saved by one car a year if 300 days of work a year are calculated. Regardless of other factors, the cost can be recovered within eight months by simply saving electricity. In six years, 46998 yuan of electricity was saved. After deducting the cost and maintenance cost, 40798 yuan was saved in six years.
4. Improving productivity
(1) Due to the variable frequency governor, it has the function of stepless speed regulation. It does not need to change the belt pulley. It can change the speed anytime and anywhere, so as to improve the production efficiency.
(2) The built-in simple PLC programmable control can realize multi-stage speed automatic energy-saving operation by setting the time and speed. If the machine needs maintenance or shift and stops, the program can be suspended by simple PLC stop button.
(3) The application of frequency converter has great influence on spinning output. By greatly increasing the spinning speed of middle spinning, the output of spinning frame can be increased under the condition of basically unchanged end breakage. In many domestic spinning mills, the warp has been received obvious results. In order to increase the output, many textile mills can only increase the number of spinning frames and spindles. We should change our thinking. It is better to improve the production efficiency of each spindle and increase the output of single spinning frame? In this way, the output can be increased and the competitiveness of enterprises can be increased without increasing equipment, workshops and workers.
5. Prolonging the service life of the machine
In particular, frequency conversion has the function of soft start and soft stop. It can reduce the impact current when the motor starts, reduce the impact on the power grid, reduce the mechanical inertia wear, and greatly extend the service life of the motor and mechanical bearings.
6. Reduce maintenance workload
Frequency conversion can provide on-line monitoring of current, voltage, motor speed, feedback information, time, fault, etc., and has automatic constant voltage control, speed tracking start control, to protect the motor and reduce maintenance workload.
