This article introduces how the frequency converter can realize frequency conversion speed regulation and automatic transformation in imported carpet textile machinery, and describes the process of the carpet machine using the frequency converter to control the positioning, slow start, and speed during operation. Satisfying the requirements of textile technology, greatly improving the quality of textiles and reducing the labor intensity of operators.
I. Introduction
The frequency converter is recognized as the most ideal and promising speed regulation method at home and abroad due to its excellent speed regulation, starting and braking performance, high efficiency and remarkable power saving effect, and wide application fields. As a high-tech product, the frequency converter has the characteristics of energy saving and environmental protection (the two major themes of today's world economic development), and it is getting more and more attention. It gradually replaces DC speed regulation and has an important position in the transmission system. In recent years, with the continuous improvement of the technical level of textile machinery electromechanical integration, AC frequency conversion speed regulation has become a trend. Almost all of the newly developed textile machinery products have used AC asynchronous motor frequency conversion speed regulation devices.
Many existing textile machines in many Chinese textile factories were imported from abroad in the 1980s and 1990s, especially in the United States, the United Kingdom, and Japan. This equipment is old and the level of automation is not high. But the new equipment produced now basically realizes the mechanical and electrical integration, centralized control system, production efficiency and quality have been greatly improved, but the equipment cost is quite expensive. Now the majority of industrial control personnel have paid great attention to the automation and frequency conversion of textile machinery.
Second, the working principle of the frequency conversion of the carpet machine
This carpet machine was produced in the United States in the 1980s. The entire electrical control structure is relatively simple, the level of automation is low, and the labor intensity of the workers is large. After referring to the working principle and technological requirements of modern imported textile machinery. We have carried out the following technical transformation of this equipment.
Choose one inverter DNV3100 series 15KW inverter (with braking resistor) to simultaneously control two 5.5KW spindle motors, assisted by Omron's photoelectric switch, Schmersal safety cable switch, German P + K proximity switch and other detection components , Control the start, stop, alarm, full yarn and doffing of the whole machine.
1. The working process of frequency converter speed regulation
The spinning machine needs a slow start, slow stop, yarn breakage, full yarn accurate stop process, the whole process of frequency converter speed regulation is as follows
2. Start-up and shutdown process
The motor needs to be prompted for 2s before running, and a 60dB buzzer will beep for 2s before starting to remind the operator to exit the needle work area. In order to overcome the shortcomings of weak start and unsmooth start when starting, the starting frequency is set to 6hz, the starting torque is appropriately increased, and another function of the inverter, the S curve, is added to the starting process, so that it has a slow The startup function has a smoother startup process, which makes people feel the speed change during the ascent from low speed. This solves the problem of frequent motor burnout during direct start, and prevents the occurrence of roving details and broken ends.
In the case of yarn breakage stop, full yarn stop or safety protection stop, the S curve deceleration process is also used. Another special requirement for the roving machine to stop is the positioning of the spindle wing. After the machine decelerates to stop, the spindle wing stops at the same position, the needle exits the cloth layer, 3mm away from the cloth surface (within 1% accuracy) for easy operation Worker's operation. We use the programmable input and output terminals of the inverter and PLC programming to achieve the key points of this technical requirement. The specific process is this. When the inverter decelerates to a set frequency of 6hz, it uses a programmable relay to output a signal to the PLC. After the PLC judges the signal, it outputs a jog signal to the inverter to keep the 6hz low-speed operation for a certain time. At this time, the photoelectric proximity switch starts to work, detects the position detection point installed on the ingot wing wheel, and detects and outputs the switching signal to the PLC. The PLC counts once once after the wheel rotates. After the count is twice, the PLC outputs a signal to the inverter to turn off At the same time, the electromagnetic clutch is activated.
3. Realization of frequency conversion jog
Frequent jogging is another feature of the carpet machine. The jog of the carpet machine will keep running at a certain frequency as long as the jog button is pressed. This low-speed operation is for the convenience of operation, needle testing and maintenance. Requires low-speed operation and can stop at any position. However, the inverter cannot work under 6hz for a long time, and continuous and frequent jogging will cause overcurrent protection. We add a judgment program in the PLC, that is, within a certain time, continuous jog only responds once. When jogging, we do not require exact position to stop, so we add another judgment program in PLC programming to judge whether it is jogging or normal operation. If it is jogging, it will not respond to the prompt sound, the proximity switch will not work, and the electromagnetic clutch will continue to work. Because of its rich programmable instructions, PLC can fully realize these functions. Dien Electric Inverter also has perfect programmable external control terminal input and output, which can be easily connected to PLC. The wiring diagram of the external control terminal of the inverter is as follows:
4. Emergency stop system
In this equipment transformation, we have added many functions: install a safety cable switch before and after the equipment. In an emergency, workers can easily pull the cable to stop the motor immediately. We chose the optical fiber type photoelectric sensor as the detection of disconnection. After the disconnection, the thread floats across the photoelectric detection area, the photoelectric switch acts, and outputs a signal to the PLC. The PLC issues a warning and stops.
Since the rotation of the spindle has a certain inertia, and there is a rapid stop process during the operation of the equipment, the frequency converter is added with a braking resistor to achieve energy consumption braking, ensuring that the frequency converter will not be overvoltage protected.
3. Effect analysis
After being transformed and put into operation, Dien Electric frequency converter equipment is stable and reliable in operation, easy to operate, and has achieved significant economic benefits. After adopting frequency conversion speed regulation, the motor speed can be adjusted as needed to improve production efficiency. The motor runs stably, the quality of the carpet surface is significantly improved, and after the accurate position is stopped, there is no trace left by the shutdown on the woven carpet. The safety protection system is perfect, and the labor intensity of workers is greatly reduced.
4. Conclusion
With the continuous improvement of the level of automation, production equipment is becoming more and more advanced, and product quality is constantly improving. Only products of good quality can be invincible in the market competition. China's existing textile equipment is relatively old, and imported advanced equipment is expensive. The use of inverter, PLC and other automation technologies to transform existing equipment can save equipment costs and improve product quality and production efficiency.
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