Application of frequency conversion speed regulati

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Application of variable frequency speed regulation in strip steel color coating production line

Abstract: in the unit of strip steel color coating production line, the roller coater adopts frequency converter speed regulation control, and the frequency converter is connected with PLC control equipment through Fieldbus proufibs to form a communication network control system to realize the process operation and speed control of the roller coater. Due to the network control, the roller coater can adjust the speed of each roller at any time according to the production state of the whole line, To ensure the surface coating quality of strip steel

key words: frequency converter; Roller coater; Proufibus

1 overview

roller coating machine is the key equipment in the strip steel color coating production line. Its operation determines the descending thickness and coating quality, and directly affects the operation rate of the machine button. Therefore, it is necessary to correctly select the more appropriate coating equipment and the best coating process. The roller coater is the most widely used coating equipment at present. It has the advantages of flexible process, convenient operation, coating saving and easy control of coating thickness

the roll coating sail is generally named according to the roll coating method, such as two roll edge machine, three roll roller machine, forward roll scribing machine, reverse roll rubber machine, etc. there are many basic types of roll coating methods. On the same roll dissolving machine, different roll coating methods can be used, which mainly depends on the process situation. The most commonly used roll coating methods are natural roll coating method, natural reverse method and full reverse method. In order to meet the needs of various wiping l materials, coating thickness and different base materials, and ensure the different speed ratio between each roll and strip steel required by the process, at present, each coating roller base car of the roller coater is driven separately. In the 1250mm wide-band steel color coating production line of Nanfang iron and steel company, the roller Dai machine is a two roll roller coater, and the roller coating method is a two roll natural reversal method

2 working principle of two roll natural inversion method

it can be seen from Figure 1 that the working principle of two roll self inversion method is that the rotation direction of the coating roll is opposite to that of the actinide belt, and the rotation direction of the adhesive roll runs opposite to that of the coating roll. The control of steel plate coating thickness is realized by changing the relative speed and gap (extrusion force) of each roll. When the gap between rolls is certain, the speed of the scribing roll should follow the speed change of the support roll, that is, the running speed of the steel strip (unit). The running speed of the unit is set as 100%. Generally, the speed of the coating roll is 50% ~ 150% of the running speed of the steel strip, and the speed of the bonding roll is about 20% ~ 60% of the running speed of the steel strip. However, due to different coatings, different substrates and different coating thickness requirements. Therefore, the construction degree of each roller is sometimes determined according to the production process, which is determined by the characteristics of the polyester layer process. In view of this characteristic, we choose the variable value drive for the coating roller driving device, and carry out process operation and speed control through network communication. In practical application, the system is easy to operate and can meet the speed of each work roll required by different process requirements. Greatly save equipment success rate and production cost. The system control system is shown in Figure 2

(1) selection of inverter motor

the running speed of the color coating line unit of Southern iron and steel company is not high, and the running speed of the strip steel is generally between 30-40/min. the coating roller motor usually operates at low speed to ensure the uniformity of the surface layer of the strip steel. Therefore, the coating roller motor is required to have good low-speed performance, smooth torque and maintain constant torque during low-frequency operation. Ordinary three-phase asynchronous motor is difficult to meet this requirement, Therefore, our roller coating motor selects y1sp series variable value adjustable catch three-phase asynchronous motor produced by Shanghai Nanyang Electric Machinery Factory. This series of variable frequency adjustable speed three cap asynchronous motor is specially designed to cooperate with various high-performance IGBT pulse width word system inverters at home and abroad. The motor has strong overload capacity in high-frequency operation and maintains constant torque output in low-frequency operation. And it is generally not necessary to use an external filter. Ytsp series has two cooling methods: one is ic411 series and the other is 1c416 series. We have selected ic416 series. Tan series has a separate axial flow fan for forced ventilation, which can ensure that the temperature rise of the motor does not exceed the allowable value when running at low speed (5Hz)

according to the performance characteristics and control requirements of the coating roller transformer motor, according to the rated parameters of the motor and considering a certain margin, we select Siemens micro-master440 frequency converter to control the coating roller motor. Micromaster 440 frequency converter is a new generation of Siemens frequency converter. In addition to the basic functions of other similar frequency converters, it has the following unique functions: it adopts flexible configuration design, can configure different operation panels as required, and has built-in RS485/232 interface, which is convenient to communicate with the upper computer. Simovis debugging software can be used to provide PROFIBUS options, which is compatible with Siemens profidrive software, so as to realize the fully integrated automation system. The vector control of Micromaster 440 has excellent torque output characteristics at low frequency and reverse rotation. The local interface and PROFIBUS can be used to realize the diagnosis function at the same time

(2) variable frequency speed regulation control system of coating roller motor

① the control of the motor speed by the frequency converter can be realized in many ways, that is, the local control can be realized by the keys on the front panel of the frequency converter, can also be controlled by PROFIBUS field bus, and can also be controlled by the analog input of potentiometer on the operating platform

② the frequency converter controlling the gluing roller and coating roller motor is equipped with PROFIBUS module, which is connected with the bus through pr0nbus interface. Together with other transmission systems of the production line and PLC, it forms a pr0nbus fieldbus control system

⑧ realization process of variable frequency motor speed control: PLC reads the speed value of the transmission device on the production line through Profibus fieldbus, that is, the speed of the strip steel on the production line, and then calculates the speed relationship between the gluing roll and the coating roll of the roll coater according to the working principle of two roll natural inversion method, and transmits the calculation result to the frequency converter through Fieldbus to control the motor speed, However, due to different coatings, different substrates and different required coating thickness, different speed signal values should be allocated to the speed of bonding roller and coating roller, which can be realized in two ways: 1. Make a process table in advance, select a working state in the process table according to the process requirements, and allocate the process speed to the bonding roller and coating roller of roller coater. 2. It can be adjusted manually through the potentiometer on the console. The signal of the potentiometer on the console is also transmitted to the canthus through the fieldbus. The PLC superimposes the value from the potentiometer on the console with the value previously calculated by the PLC, and then transmits the final calculation result to the frequency converter to adjust the speed value of the gluing roller and the coating roller of the applicator, so as to meet the requirements of the production process

④ ABS has good mechanical property control. The experimental machine we usually see should actually be called the material experimental machine. The operating platform is equipped with a speedometer of the actual speed of the gluing roller and the gluing roller, which is used to display the actual linear speed of the gluing roller and the gluing roller. At the same time, the control console is also equipped with a signal display device for the working state of the gluing roller and the gluing roller

3 operation effect and summary

the roller coater adopts frequency converter speed regulation system, which meets the requirements of process production, saves investment and facilitates equipment installation and commissioning. Since the roller coater of Nanfang iron and steel company was put into operation in 2003, the equipment has operated stably, the amount of equipment maintenance work is less, the equipment productivity has been improved, and good economic benefits due to the existence of stress concentration have been achieved. The roller coating machine adopts frequency converter speed regulation system and PROFIBUS field bus control, which can not only meet the requirements of industrial control system of modern enterprises, but also have stable operation, flexible operation and convenient debugging

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