I. Introduction
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In the aluminum-plastic composite pipe production line, several heating zones are involved, such as the barrel heating zone, the flange heating zone, and the die heating zone. In practice, at least one to two temperatures are required in each heating zone. Control table to set the temperature and output heating control temperature. The temperature control table of traditional equipment can only be observed and set temperature manually to achieve the temperature control of the corresponding heating zone, and cannot be controlled in a centralized manner. With the improvement of 3C (computer, communication, and control) technologies, the communication field has also undergone earth-shaking changes. Now that communication between a temperature control meter with communication functions and a touch screen is selected, centralized control can be fully realized. A touch screen can communicate with 31 temperature control meters at the same time. The communication method is RS-485 serial communication. In this way, all the parameters in the temperature control table can be seen in the touch screen at a glance. Convenient to modify the settings of the parameters in the temperature control table.
Second, the system introduced
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This article takes the Fuji touch screen and temperature control table as an example to introduce its practical application in the aluminum-plastic composite pipe production line.
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1, electrical system
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The entire system uses a programmable controller (PLC), touch screen, temperature control meter, frequency converter and other electrical accessories.
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(1) Touch screen
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Touch screen selection Fuji UG420H-SC1, 10.4-inch, 128-color STN display, can communicate with nearly 30 manufacturers of PLC, highly compatible, but also can communicate with computers (open communication protocol), based on Windows95/98/NT operation The dedicated configuration software under the platform is friendly and intuitive, easy to learn and use, and it greatly saves the product development cycle. And the product model is complete with 5.7, 7.7, 10.4, 12.1 inch monochrome color, etc., to facilitate the selection. With RS232/422/485 communication port, convenient to connect PLC and peripheral products of other manufacturers (such as: bar code, memory card, inverter, personal computer, etc.). A large number of graphic libraries (switches, lamps, bar graphs, etc.) are available for selection in the programming software, and the required process graphics can be edited according to the user’s needs, and the BMP files and DXF files in AUTOCAD can be converted. Also has a message board function for shift record use. In the programming software, the closing time of the backlight of the touch screen can be set to save its service life. The touch screen has internal programming instructions – macro commands, which can ease the PLC programming burden, and even some simple devices can replace the PLC, and the touch screen programming directly communicates with other devices. The parallel port on the touch screen can also be directly connected to the printer for real-time or scheduled printing of current or historical data. This system adopts UG420H-SC1 to communicate with SIEMENS S7-200CPU226 through different communication ports at the same time, and FUJI PXR4 temperature control table communicates in RS-485 mode. After selecting the touch screen and PLC model in the programming software, select FUJI PXR (which can also communicate with other manufacturer’s temperature control meter) in the system settings, and use another communication port and temperature control table in the touch screen. communication. The baud rate for communication with the Fuji PXR4 is 9600 bps; parity is odd parity; data length is 8 bits; stop bit is 1 bit; communication method is RS-485.
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(2) Temperature control table
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Use Fuji’s PXR4 temperature control meter with communication function. It is a new type of temperature control table introduced by Fuji Electric. It has RS-232/485 communication function and has self-tuning function. It automatically sets PID parameters through the measurement and calculation functions of the controller. With fuzzy control function, fuzzy operation is used to suppress overshoot to improve the response to external disturbances. Absolute value alarm, deviation alarm, etc. It also has various functions such as output limitation, parameter masking, slope/insulation and so on.
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2, system production process
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The aluminum-plastic composite pipe consists of five layers of inner pipe, inner rubber, aluminum pipe, outer rubber and outer pipe. The material production sequence is divided into 65 mm inner pipe extruders (4 fuselage heating zones and 3 machine heads). Heating zone), 45mm inner plastic extruder (3 heating zones in the fuselage, 3 heating zones in the machine head), automatic vertical displacement constant tension tractor (without heating zone), 45mm outer plastic extruder (body 3 Heating area, head 3 heating areas) 65mm outer tube extruder (4 heating zones in the fuselage, 3 heating zones in the machine head). Therefore, there are 26 temperature controlled heating zones that need to be controlled, and 26 temperature control tables are controlled by a touch screen. The
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When the system is powered on, first start the temperature control, that is, when the temperature control table is powered on, the inverter cannot be powered on. After the power is turned on, 2 commands are sent to each temperature control table immediately. 1 The output of the temperature control table is prohibited from heating (does not affect the actual measurement. Temperature (2) is to set a lower initial heating temperature, because the thermocouple is inserted inside the heating zone, the heating ring is on the outside, so as to avoid uneven heating temperature over the entire heating ring. The initial value of the power-up for the 26 heating zones can be the same. After the power is turned on, if the communication detection is normal, the parameters of each heating zone will be displayed on the touch screen, the temperature of each heating zone may be set on the touch screen, and the heating allow/disable status of each heating zone may also be changed on the touch screen. The above two commands are regarded as randomly occurring, and can also be implemented in the read temperature control table in the interrupt measurement mode. For the temperature setting of each heating zone, a numeric keypad in the touch screen may be used. When a certain temperature in a certain heating zone is set, the setting zone of the heating zone is clicked and a setting keyboard pops up to set the zone. After pressing the “Confirm” key, the keyboard will automatically close, which is convenient and clear.
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In order to maximize the actual temperature refresh rate of the 26 heating zones displayed in the touch screen, the “relay” communication reading mode is adopted, that is, when reading a zone (there are 3 situations: success, verification error, and communication timeout) Take the next district. Communication error processing: An error counter can be set for the communication of each slave station. This counter is incremented when a slave communication check or communication time-out error occurs, and is automatically cleared after the communication is successful. When a certain counter is increased to a preset value (the touch screen can be modified), the buzzer will alarm, and the communication failure alarm screen will pop up, and details how to deal with it. During operation of the system, if an overheat/low temperature alarm occurs in a certain heating zone, the “Alarm” alarm lamp on the temperature control table turns to red, and at the same time, alarm information is immediately popped up in the touchscreen, such as: alarm time, fault handling method, etc. Easy and timely troubleshooting. Truly reflect the uniqueness of the touch screen – man-machine dialogue. The touch screen itself has a “recipe” function, and its internal macros can store different process recipes of different products in it, calling it at any time, and greatly improving work efficiency.
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Third, the conclusion
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The system has been successfully run in a factory in Zhejiang for more than four years. The on-site operation proves that the electrical system is reasonable in terms of software and hardware design, reliable operation, and has strong anti-interference, so that the level of industrial automation A new step has been made and it is worth promoting in the extruder industry.
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