Drive control system 0 of the hottest paper machin

2022-09-21
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The drive control system of the paper machine division

many old paper machines use a single DC motor drive, which distributes the speed mechanically. Due to mechanical wear, belt slipping and other factors in the production process, the speed matching is out of balance, which is easy to form paper breaks and uneven thickness. At the same time, due to the high temperature and humidity on site, the maintenance of the motor is increased. In order to optimize product quality and improve labor productivity, the vice president has changed it to multi motor segment transmission on site, that is, cancel the mechanical transmission part of DC motor and its power, install AC motor in each transmission segment, and adopt AC multi-point transmission mode

1. requirements of paper machine for transmission control. The transmission of paper machine includes sections such as the press, dryer, sizing, calendering, coiling, etc. Its transmission is variable speed transmission. In order to meet the needs of the change of paper characteristics in the production process, the transmission of the paper machine must be able to adjust the speed within a certain range, and the speed of each segment can be adjusted independently. A. The speed of each segment is accurate and easy to adjust. B. High transmission efficiency, reducing power by 10%-15%. C. The load control and transmission management of each part are convenient. D. It is convenient for automatic control and adjustment of the production process, reducing maintenance costs and saving labor

2. inverter selection according to the control requirements of paper machine for transmission, Siemens vector frequency converter 6SE70 is selected, with the following characteristics: A. standardization and modularization. The structure of the whole inverter is very compact. The main board and expansion board are connected through bus slots, and each component is close to facilitate maintenance. Due to the improvement of integration, the device has high reliability. B. It has good disturbance performance, reliable operation, is not affected by component aging and temperature drift, and can maintain stable control accuracy for a long time. C. It adapts to a wide range of power supply voltage fluctuations and can automatically adapt to the change of electrical frequency Hz. D. It has a strong self diagnosis and processing function, and provides supplementary information about the cause of the fault, making troubleshooting easier and convenient for maintenance. E. Flexible communication capability. It can be communicated and connected in various ways, such as USs, peer to peer, PROFIBUS-DP, can, SIMOLINK, etc

3. synchronization in the papermaking process, it is particularly important to keep the synchronous operation between the transmission subsystems. This synchronization is not only required for stable speed operation, but also the thermal insulation material, thickness and thermal performance parameters of its enclosure structure should be written into the residential operation manual. It is also necessary to ensure the consistency of linear speed in the dynamic process of acceleration and deceleration. To this end, we take the following two measures to achieve the purpose of synchronization

3.1 improve the dynamics of the system. At this time, the machine automatically prints out the sample number, the values of f1p1 and f2p2 and the experimental stiffness p12 value. In response, all frequency converters adopt the feedback mode of photoelectric encoder. Through vector operation, it can determine and control the current components of torque and magnetic flux, and obtain dynamic characteristics comparable to DC transmission. This ensures the realization of synchronization on the basis

3.2 establish a speed setting value chain and establish a device to device communication process between each frequency converter. In this way, the speed setting value can be quickly and accurately calculated by digital quantity. After the end of the experiment, the arithmetic mean value of 10 samples can be automatically calculated and accurately transmitted to the first frequency converter, eliminating the adverse effects of signal drift and interference caused by line loss and interference in the transmission of simulated signals. The different mechanical changes between each segment are controlled by different scale factors inside the frequency converter, so as to realize the constant proportional operation of the linear speed of each segment in dynamic and steady state

the frequency converter option board scb2 has an electrically isolated RS485 port, which can realize device to device connection between multi-function frequency converters through x129. Here, we adopt the parallel connection method, using one frequency converter as the driving device and the other as the driven device, so that the driving device can transmit the given value of the system linear speed to the driven device, thereby increasing the reliability of the whole system. Through the transformation of the paper machine production line, users believe that the use of frequency conversion speed regulation system has significant advantages in improving product quality, output, reducing daily maintenance and energy saving, and can fully meet the needs of the production site

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