Emergency treatment method for the most fire syste

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The speed of modern paper machine has been increased to about 2000m/min, and the requirements for quality control are also very high. If there is a problem in a key part, it will affect the product quality requirements of the company, and some even have to stop for treatment. Therefore, when there is a fault in production, emergency treatment is very important. The following describes an emergency treatment method for the failure of Nipco controllable medium and high roller control system

Nipco controllable medium and high rollers in the Press Department of 3800 workshop of Shandong Quanlin Paper Co., Ltd. are controlled by zones, which are divided into 6 positive pressure zones and 2 reverse pressure zones, of which z1-z6 are positive pressure zones, each zone is equipped with a 0-10mpa pressure transmitter and a ± 50mA servo valve; There are 3 oil cylinders in Z1 and Z6 zones, 6 oil cylinders in Z2 and Z5 zones, and 4 oil cylinders in Z3 and Z4 zones respectively- Z1, -z6 is the degree position of the experimental machine found in the negative pressure area: the main body degree of the hydraulic universal experimental machine, equipped with a 0-10mpa pressure transmitter and a 2 Comprehensive protection of safety equipment: the safety equipment of the facility is a ± 50mA servo valve used to protect the personal safety of mechanical facilities and laboratory personnel. There are two oil cylinders in -z1 and -z6 zones respectively, and the whole medium and high roller has a total of 30 oil cylinders, with a width of 3.8m

when the controllable medium and high roll hydraulic station is started and normal, turn the roll closing switch, the Nipco roll rises and closes with the upper roll. After it is closed in place, the drive of the press section is allowed to start; Then turn the loading rotary switch of the console to the load position. When the paper web detection switch detects the whole paper web, the Nipco roller automatically loads the setting value of the equalizer pressure (mlk), and the setting value of the equalizer pressure can be adjusted according to the process requirements. There is a different functional relationship between the average pressure and the pressure in each pressure zone, and the pressure in z1-z6 pressure zone can be adjusted separately. After the paper breaks, it will be unloaded to the closed state automatically, and after the whole paper is loaded automatically

the pressure zone control process is shown in Figure 1

Figure 1 pressure zone control process

1 failure treatment analysis

1.1 failure phenomenon

nipco controllable medium and high roller failure just occurred, the individual pressure zones of the control system frequently released pressure, and then each pressure zone could not be pressed. In this way, the dehydration of wet paper was not good, resulting in frequent paper breaks in the press section, unable to produce normally, and forced to reduce the speed

1.2 fault analysis

because there is a problem with the control system, first change the system from automatic state to manual state. Because in the manual state, each pressure zone can be directly controlled manually through the monitoring board and servo amplifier board, even if the circuit board in front of it fails, the system can also display and control, so it can operate in the manual state. However, it still doesn't work.

so it is used again Use a multimeter to measure the current of the servo board and observe whether the current also fluctuates. As a result, there is no current output

after the above inspection, it is confirmed that the monitoring circuit board is broken

2 solution

according to the analysis of the circuit, the system is temporarily treated as follows: 1 DC stabilized voltage power supply and 1 24V DC switching power supply, 21 5K potentiometers, 6 digital display meters, 3 potentiometers in series with the servo valve in each pressure zone to supply 5V voltage, and generate current to adjust the servo valve. If the pressure is too high (low) to be adjusted, the positive and negative poles of the power supply can be replaced, which can be solved; Similarly, connect each pressure transmitter in series with the digital display meter and switching power supply to display the pressure in each pressure zone; Manually adjust the pressure of each pressure zone according to the pressure display of each pressure zone and the moisture display of QCS system. In this way, it not only ensures that the orders of normal extruder enterprises will be significantly recovered, and saves the company's major economic losses, but also gives the supply department sufficient time to purchase spare parts

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