Application of AC Frequency Conversion Technology in New Textile Equipment and Retrofit of Old Machines

1. Introduction In the fierce market competition in the past 10 years, domestic and foreign textile machinery manufacturers have adopted PLC control, frequency control, electromechanical integration, etc. to replace the traditional mechanical structure with electronic technology, and improve the reliability of the entire textile machinery. Sex, improve the quality and degree of automation of spinning, expand the adaptability of the variety, easy to use. All textile manufacturers also invest in retrofitting old machine equipment. There is a more used technology - AC variable frequency speed control technology.

2. Advantages of AC frequency conversion speed control technology AC frequency conversion speed control technology has been rapidly popularized and promoted in some technologically advanced countries in the past 20 years, and gradually dominated in electronic dragging, forming the theory of power electronics. Power electronics is the use of electronic semiconductor components for power conversion and control technology. In 1973, the Electrical Society of America, at its conference on power electronics, defined power electronics as the technical discipline that studied the marginal fields of electrical electronics and control. Power electronics is an AC asynchronous motor that is not suitable for speed control and has the same speed control performance as a DC motor.
AC frequency conversion speed control drive has the following characteristics:
1, can make ordinary asynchronous motor stepless speed regulation.
2. Startup current is small, reducing the power equipment capacity.
3, start smooth, eliminate mechanical impact, protect machinery and equipment.
4, the motor has a protective function, reduce motor maintenance costs.
5, has a significant power-saving effect.
As the AC variable frequency speed control drive technology has the above characteristics, it has begun to replace the DC speed control device and become the development direction of modern electric drive.

3, the necessity of the application of AC frequency conversion technology in cotton textile equipment
In the spinning process flow, the electrical driving of the processing equipment is required to be stable, and the jogging, starting, and lifting speeds should all be smoothly achieved. In this way, the drafting of the fiber is uniform, and the uneven weight and the dry CV value are reduced. In the transmission system of cotton spinning equipment, belts and gears are all responsible. Due to the hardness of motor starting, belt slipping and gear impact are inevitable during the jogging and starting. In mechanical transmission trains, the more gears there are, the greater the chance of damage to the gears. Applying AC inverter technology can solve the problem of smooth startup, eliminate the impact of mechanical startup, achieve stepless speed regulation, and satisfy the production process. Requirements, improve the quality of yarn. When this technology is used to change yarn types, it is not necessary to change the teeth or the pulley. The change of the process speed of the equipment can be accomplished simply by setting the frequency conversion.

4. Application of AC Frequency Conversion Technology in Textile Equipment
4.1 AC frequency conversion speed regulation has been widely used in new domestic cotton spinning equipment. In the 7th China International Textile Machinery Exhibition in 2000, FA201B card machines, FA326 drawframe machines, FA423 roving machines, FA710 high-speed drawframes, and FA231 twisters were all adopting frequency control. The new domestic spinning frame F1513 series and F0128 series adopt PLC, programmable control, frequency conversion speed regulation, spinning can be speed-controlled spinning according to the setting procedure. Especially EJM128JL type spinning frame 1008 spindles, the spindle speed can be controlled by 10 stages of frequency control. The FA 716 is based on collective variable frequency speed control, and can also be used after different types of requirements, the implementation of single spindles, grouping or subsection frequency control, to meet the requirements of many varieties of cotton yarn winding and winding.
4.2 The application of AC variable frequency speed regulation in carding machine.
4.2.1 In the design of the old carding machine, due to the technical conditions at the time, equipment manufacturing costs, market needs and other factors, there are inevitable deficiencies. For example, the electromagnetic clutch in the drive system of the A186D carding machine is often caused to stop because of the high failure rate. From time to time, a fire alarm occurs, causing a certain loss to the production efficiency and product quality. It requires a lot of manpower and material resources to maintain and maintain. Some companies have used inertial wheel electromagnetic clutches. In this way, thin strips are produced in the process of slow turn of Doffer. In severe cases, there is a broken edge, and the phenomenon of broken cotton nets affects the quality of the sliver. In order to avoid this phenomenon, some companies use improper methods of operation to make up for the above-mentioned equipment defects, but it is also undesirable to create a large number of scraps.
4.2.2 The process of improving the running status of the carding machine. A186D card machine In order to make Doffer achieve up and down speed smooth, in the mechanical transmission design two-speed motor, inertia wheel, electromagnetic clutch, electrical and mechanical means to achieve. In the design of the A186E, A186F, and FA201 carding machines, the star-triangle conversion control system was added to the motor, thereby further improving the ascent and descent speed slopes. FA201B, FA212 carding machine adopts AC variable speed control, which can achieve arbitrary adjustment of the Dov's speed-up slope, and any variable function of the doffer process speed. Provide a good example for the transformation of old machines. The A186D old machine is undergoing AC frequency conversion and speed control transformation, which will not only improve equipment performance, but also reduce downtime. It can also increase production efficiency and sliver quality.
4.3 The application of variable frequency speed regulation on the roving frame replaces the anti-detail device. The bobbin winding of the roving frame and the rotation speed of the front roller are likely to be different during the start and stop, resulting in too much and too small tension of the roving, so that it is easy to form rough details of the roving, in order to reduce the occurrence of coarse details in the roving frame. Transmission design reactor, time relay plus electromagnetic clutch, collectively referred to as anti-detail device. The role of the reactor is to make the main motor in a three-phase unbalanced state when the roving frame is started, thereby reducing the starting torque of the motor and achieving the purpose of soft start. The time relay and the electromagnetic clutch are the iron gun and the bobbin when the roving frame is stopped. The winding phase is disengaged, the bobbin stops winding, and the front roller still continues to output the roving with inertia, and the roving between the roller and the flyer has a certain degree of slack so as to prevent excessive tension when the roving is driven again.
This kind of anti-detail device has serious defects in actual use. One is that the reactor string is in one phase of the three-phase circuit. The three-phase unbalanced principle is used to reduce the starting torque of the motor. After the roving machine is started, the reactor is shorted by the time relay to restore the three-phase balance of the motor. Put into normal operation. If there is a problem with the time relay, the motor will be in a three-phase unbalanced operation for a long time, causing the motor to overheat and burn out. The second is that the clutching time of the electromagnetic clutch for parking is achieved through the adjustment of the two time relays, which makes it more difficult to grasp the degree of slackness of rovings. In addition, the malfunction of the electromagnetic clutch is also high; therefore, such anti-detail devices are There is very little that can be maintained in actual production, and the problem of preventing rovings from being detailed has not been well resolved. At present, new types of roving machines and old machines are transformed using AC frequency conversion technology. Solve this process problem. After testing the yarn quality of the FA413 roving machine before and after its transformation, the CV% of the roving bar at the start-up segment was decreased by 2-3%, and the coarse yarn detail was reduced by more than 90%.
4.4 The application of variable frequency speed regulation on the sizing machine reduces the mechanical structure and the motor. In the G142 series sizing old machine transformation using AC frequency control, to reduce the original design of the first set of mechanical continuously variable transmission, while eliminating the need for a servo motor and a slow motor. In satisfying the sizing process, the speed is changed from the slow speed, the host plus the lift speed to the uninterrupted stepless speed regulation of the speed of the process road by the starter road. Adjusting the pressure for changes in the speed of the vehicle | The sizing sizing rate is now balanced.
4.5 The application of variable frequency speed regulation in textile and air conditioning has made energy conservation significantly. In the application of air-conditioning fan control, the fan can be steplessly speed-regulated according to the environmental conditions of the workshop, and the adjustment range is expanded. Because most of the fans work in 50-80% efficiency, the power-saving effect is as high as 60%. In the pump control application, the speed of the water supply pump can be adjusted according to the amount of water, achieving energy saving and achieving near constant pressure water supply.

5. The feasibility of the application of AC variable frequency speed control technology in cotton textile equipment The AC variable frequency speed control technology has been widely used in new domestic cotton textile equipment. There is very little promotion and application of cotton textile equipment currently in service. The editor-in-chief of the Cotton Textile Technology magazine Zhai Lei once mentioned the issue of adopting high and new technology to transform traditional textile equipment in the article “Thinking and Proposing for Technical Progress in China's Textile Industry” [2000.1]. Most cotton and textile companies currently use equipment VII and VIII. For the equipment produced in the ten years, these devices can still be used for a considerable period of time in terms of the mechanical state. All recent updates are impossible, but it is entirely feasible to carry out partial electric drive modifications.
Take the example of the implementation of frequency conversion technology in the two processes of carding and roving. A cotton spinning enterprise with a production capacity of 50,000 spindles, equipped with about 80 sets of carding processes, and about 20 sets of roving processes. If the carding machine is a 186D or A186F type, the conversion fee A is about 280,000 yuan, but the electromagnetic clutch, 2 contactors, intermediate relays and rectifiers etc. are cancelled during the conversion of frequency conversion technology. These electrical materials saved nearly 1,000 yuan. He effectively protected Doffer motor and Doffer drive trains, reduced the failure rate, and reduced maintenance costs. This saved 1200 yuan in material costs per unit, and saved 96,000 yuan in 80 units. Through simple calculations, the payback period is 4.35 years, and the total investment return rate is 22.97%. Roving machine frequency conversion technology also has a good price. The total cost of the roving process is 220,000 yuan, which also saves material consumption such as reactors, contactors, time relays and electromagnetic clutches.

6. Concluding remarks
The application of AC frequency conversion speed regulation technology in cotton textile equipment is necessary. It is also feasible to popularize and apply traditional cotton textile equipment. The use of AC frequency conversion technology in cotton textile equipment currently in service is relatively small. There are many factors here: First, most of the equipment currently in operation appeared in the 1970s and 1980s, but this new technology has not yet been applied. Second, the benefits of the cotton textile industry in recent years have been poor and they have not been able to apply this new technology. In the selection of equipment, due to the price difference factors, equipment with new technology was abandoned; third, the management level and maintenance power were not good, and they did not dare to use equipment with high technical content. With the progress of society, the development of technology and accession to the WTO, we must improve the equipment level of our country's existing cotton textile equipment, increase our technological content, and increase the competitiveness of cotton yarn and cloth in the international market. Therefore, the high-tech AC variable frequency speed control will be widely used in cotton textile equipment.