1.Introduction

The main advantage of frequency conversion transformation of spinning frame is that it can realize automatic endless speed change according to the tension change law of large, medium and small yarn, optimize spinning conditions, and keep the tension stability of each stage of spinning as much as possible. It will play a positive role in further reducing the broken head, reducing hair, achieving high quality and high yield, reducing energy consumption and reducing the labor intensity of turning workers.

2.Tension change characteristics of spinning frame

Spinning is the last process in the spinning process. In spinning production, yarn breakage is the key to affect product quality, output and energy consumption. The essence of fine yarn breakage is that it occurs when the strength of the spinning section yarn between the front roller and the yarn guide is less than the tension borne by the spinning section, so the spinning tension must be stabilized to reduce the fine yarn breakage.

The air ring is formed when the fine yarn is winding at high speed. The fluctuation of the air ring in different spinning stages affects the spinning tension and is the direct factor that causes the number of broken ends. It is very important to understand the changing characteristics of the air ring tension in a falling yarn to control the steady change of spinning tension and reduce the breakage.

The relationship between spinning tension and spindle speed: the relationship between spinning tension and spindle speed is parabolic, that is, when the spindle speed increases, the spinning tension increases with the increase, and the higher the spindle speed, the greater the increase in spinning tension.

3.Input and return

(1）The effect of increasing yield

After installing the FD200 series frequency converter produced by FGI, the spinning machine should reduce the speed of 5% ~ 8% in small yarn and large yarn (the purpose is to reduce the break rate), and increase the speed of 5% ~ 15% according to the condition of the yarn, and the length of the yarn accounts for 80% of the entire length of the yarn, that is, the overall speed of spinning increased by nearly 10%. The effective running time of the spindle is greatly improved, the production efficiency of the spinning frame is improved, and the output is increased by nearly 10%.

(2)Improve the quality of the role, reduce the breakage rate

 Fracture analysis

Yarn breakage is the main harm in spinning production: it affects the output of spinning frame and reduces the production efficiency; Increase the labor intensity of the car holder; It is easy to increase cloth surface defects and cause large quality fluctuation; Increase the consumption of recycled flowers, recycled silk and machine materials; Therefore, the broken end is the obstacle to the development of high yield, high quality, low consumption and large roll production.

Influence with spindle speed. With the increase of spindle speed, the breakage after yarn formation increases. When the spindle is rotating at a constant speed (no frequency conversion), the distribution of dotting broken ends is as follows: small yarn, large yarn less times, small yarn, the ratio is 5:3:2. Using frequency converter speed regulation, yarn breakage can be reduced by about 10 percentage points.

The breakage rate is reduced when the yarn is falling, because the reduction of the breakage can be used to save the time to do cleaning work, reduce many sudden yarn defects, and ensure the yarn quality.

(3) Save raw materials and electricity

For some difficult varieties such as strong twist yarn, core yarn, hemp and cotton yarn and high-grade combing products, by changing speed to select the best point of the production process, it can greatly improve the unit yield, reduce the post-joint, reduce the back flower, and reduce the roller flower, which is to save the waste of raw materials for rework.

Using frequency converter to control the main motor can tap the motor's no power, make full use of and improve the power factor, so as to achieve the purpose of saving electricity. Without frequency conversion, the active power of the general spinning frame is between 7.3-8.1, and the active power reaches more than 9.9 after frequency conversion, which reduces the reactive current, reduces the line loss, saves electric energy, and reduces the power consumption of the equipment in the case of the same output.

4.Increase productivity

(1) Because the frequency conversion governor has a stepless speed regulation function itself, there is no need to replace the belt disc, and the speed can be changed anytime and anywhere, thereby improving production efficiency.

(2) Built-in simple PLC programmable control, through the set time and speed, can achieve multi-speed automatic energy-saving operation. If the machine needs to be stopped for maintenance or shift, the program can be paused by the simple PLC stop button.

(3) The application of frequency converter has great influence on the spinning output. By greatly increasing the spinning speed in the spinning process, the output of the spinning frame can be increased under the condition that the broken end is basically unchanged. In many domestic spinning mills have received obvious results. In order to increase production, many textile mills can only use the method of increasing the number of spinning machines and increasing the number of spindles, we should change our thinking, by improving the production efficiency of each ingot, improving the output of a single spinning machine to achieve not better? In this way, we can increase the output and increase the competitiveness of enterprises without increasing the equipment, without increasing the plant, and without increasing the workers.

5.Extend machine life

In particular, frequency conversion has soft start and soft stop functions. Reduce the impulse current when the motor starts, reduce the impact on the power grid, reduce the mechanical inertia wear, greatly extend the service life of the motor and mechanical bearings.

6.Reduce maintenance effort

Frequency conversion can provide online monitoring of current, voltage, motor speed, feedback information, time, failure, etc., and has automatic constant voltage control, speed tracking start control, protect the motor, reduce maintenance workload.