1 Overview At the same time of transformation, the automatic control system of the instrument has also been updated. The updated post-processing control system is a set of OCS (Open Control System) control system with temperature and pressure control technology in the production process of advanced polyester staple fiber, which is closely related to product quality. System. It uses the programmable controller (ProgrammableLogic due to the reason of opening and stopping, the temperature of the short wire production process, pressure controller, referred to as PLC) to adjust and control the system parameters, the force changes greatly, the control is unstable. Since the automatic adjustment of the conventional meter is generally suitable for a stable continuous production process, the temperature and pressure adjustment of the short-wire device usually must be controlled by manually controlling the valve opening degree before and after the vehicle is stopped, which reduces the self-control rate of the post-processing instrument. The control accuracy is also reduced, and will directly affect the quality of the product. In order to better meet the production needs, improve the output and quality of short-staple products, the short-wire post-processing equipment and dynamic monitoring by industrial computer (Industrial Personal Compnter, IPC for short) greatly improved the automatic control ability and control precision, and improved The quality of short silk products. 2 polyester short-fiber post-treatment process and control requirements 2.1 post-treatment process flow post-treatment process flow see. 2.2 Post-Processing Process Control Requirements 22.1 The main control and display parameters are used in the power unit of the polyester department of Shanghai Petrochemical Co., Ltd. The engineer and the post-processing instrument mainly control and display the parameters: oil immersion tank temperature, oil bath temperature, and stretching machine temperature. , steam oven pressure, tension heat setting temperature and pressure, tension machine tension, crimp preheater pressure, crimper temperature, dryer temperature. Mainly engaged in instrumentation equipment management post-processing instrument main monitoring parameters are: first stretching machine and second stretching machine oil filter pressure, flow, temperature; third stretching oil filter pressure, flow, temperature and crimping machine pressure. 22.3 Limit (switch) control, interlock alarm and display parameter Switching parameters mainly include: first stretching machine and second stretching machine lubricating oil pressure, liquid level; oil bath level; steam heating box pressure; oil agent Spray level; three-roller guide pressure; crimp preheater pressure, crimper speed; dryer emergency shutdown. Each alarm parameter is equipped with a high alarm display, a low alarm display, a high and high interlock alarm, and a low low interlock alarm. 3 Control scheme selection The automatic control system transformation scheme should not only use advanced control technology to achieve the ideal technical requirements, but also consider the characteristics of the production process, but also make full use of the original instrumentation equipment to reduce the transformation cost as much as possible. Since the short-wire post-processing production is characterized by control and monitoring signals, the majority of the switching quantity is suitable for the PLC. PLC which mainly solves the switching logic control, so that the sequential control, interlock protection and analog loop control are integrated. That is, the integration of electronic control and instrument control. It has the following characteristics: saving investment. The system has high performance-price ratio and can make full use of existing resources. Except that the secondary instrument is replaced by the industrial computer, other instruments can be used. There are few system levels. Only the operation station and the field instrument are two layers, all control strategies are implemented in the on-site PLC module, greatly reducing maintenance and maintenance costs. The system is open. The operating station meter uses the Windows operating system and is open and easy to use. Transmission, the signal is not attenuated and the measurement is accurate, and the system control is stable. 5) The signal output from the on-site PLC control box is transmitted to the operation station by a field bus cable, which is monitored by the industrial computer, which can save a lot of cables and wire racks. Therefore, the short-wire 1 line automatic control system is modified to select an OCS control system with advanced control technology, simple and flexible operation, low investment and PLC logic programming function. 4 control scheme realization 4.1 OCS system hardware composition The entire OCS system is mainly composed of IPC, PLC and field instruments. The field instrument includes a pressure sensor, a temperature transmitter, a thermal resistance, a regulating valve, a pressure switch, a liquid level switch, and the like, and the PLC is connected to the IPC through a serial communication interface. OCS system software OCS system software includes computer operating system software, OCS software, and lower computer software. The operating system adopts the universal Windows98. The OCS software uses Intouch. The lower computer performs PID adjustment control on temperature, pressure and liquid level, and can flexibly realize the interlock, alarm, control, display and graphics required for the post-processing monitoring system of the spinning device. And printing and other functions. 5 system control principle system control principle as shown. The control principle of temperature, pressure and liquid level adjustment circuit will be described below. 51 Temperature control In the post-spinning processing operating system, the temperature is very important (continued from page 27). During the operation, stretching, heat setting, curling, drying, etc., the temperature must be strictly controlled and monitored. In the OCS system, the temperature is measured by the thermal resistance, and after being converted into a 420 mA electric signal by the transmitter, it is sent to the AI ​​module of the PLC, and the CPU is processed and processed (PID adjustment), and the result is sent to the valve controller through the AO module of the PLC. The opening of the regulating valve is controlled by the valve controller to achieve the purpose of controlling the temperature and is dynamically displayed by the IPC. 5.2 Pressure Control Due to the use of saturated steam heating, steam heating chambers and tight heat setting pressure control are important for operational safety and stability. In the OCS system, the pressure of the medium is converted into 4~20mA electric signal by the pressure sensor, and sent to the AI ​​module of the PLC. After the CPU calculates the processing (PID adjustment), the result is sent to the valve controller through the AO module of the PLC. The controller adjusts the valve opening to achieve pressure control and dynamic display on the IPC. 3 pressure, liquid level limit control post-processing process control a large number of switching signals, such as pressure switch, liquid level switch, start and stop switch. The switching signal is sent to the DI module of the PLC. The actuators for these switching signals use a two-position cylinder control valve. The 24V electric signal outputted by the DO module of the PLC directly controls the two-position four-way solenoid valve, and the solenoid valve controls the cylinder valve installed on the process pipeline. Each cylinder valve is equipped with a non-contact position switch, which sends the valve position signal to the DI module of the PLC to form a closed-loop control loop, which completes the effective control of the process requirements and is displayed and alarmed by IPC. 4 The main function of the host computer monitoring software IPC mainly realizes the following functions: setting or modifying the relevant process parameters and transmitting the parameters to the programmable controller, real-time monitoring, dynamic display, security alarm, history recording, curve drawing and Record printing, etc. 6 Conclusions The operation practice in the past few years shows that the 0CS control system with PLC logic control function can effectively improve the reliability and stability of the control system, meet the needs of continuous full-load production, and greatly improve product quality, production efficiency and economy. 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