Application of B&R PCC to realize intelligent control of extruder


With the development of the domestic construction industry and the improvement of people's living standards, plastic steel doors and windows are gradually replacing the aluminum alloy doors and windows and iron doors and windows with the characteristics of environmental protection, energy saving, aesthetics and practicality, and put high demands on the demand for profiled materials. It will inevitably promote the technical upgrading and upgrading of profile extrusion production equipment. The control system of the early profile extrusion machine adopts temperature control instrument plus relay control or simple PLC logic control. The circuit is complicated, maintenance and maintenance are difficult, and the operation is not convenient, which affects the production efficiency and the quality of the profile products. . Major foreign profile extruder manufacturers, such as Battenfeld, Cincinnati, Tyson, etc., adopted B&RPCC's intelligent control system in the early 1990s to replace the traditional control method, greatly improving the production control of the extruder. Level. Therefore, the intelligent control system based on B&RPCC will be the development direction of the automatic control system of the extruder. This paper will introduce the application of the B&R PCC control system in the Fukuda profile extrusion line.


1 B&R PCC system configuration


The control system adopts upper and lower position machine control and control mode. The upper computer adopts powerful PROVIT-2000 series industrial computer, 10.4 inch LCD display and full Chinese operation interface; the lower position machine adopts high performance programmable computer controller PCC-2003 series. The setting table and the traction cutting machine respectively adopt the CaN bus expansion module; the B&R temperature module is equipped with the PID temperature control software to replace the traditional temperature control table; and the three Fuji inverters are controlled by the RS485 bus communication mode. The control system can centrally monitor the whole line on the man-machine interface; the tractor can be controlled and adjusted in the main machine, the setting table and the traction machine, which greatly facilitates the unit to adjust the production; the inverter can be controlled by the complete digital communication mode. Synchronous speed regulation of the whole line; high-precision temperature control, current monitoring and display in the heating zone; automatic fault alarm and random help function; the entire system configuration and control functions have reached the international leading level. The system configuration block diagram is shown in Figure 1.

2 machine intelligence


2.1 Software development


B&R's PCC controller uses a time-sharing multitasking system, so control requirements can be divided into multiple tasks and executed simultaneously in one scan cycle; Windows programming environment automatonStudio supports standard C, Basic, ladder, instructions Six standard development languages, such as tables and sequential structure diagrams; can be programmed in multiple languages ​​in the same project as needed. At the same time, the programming environment contains a wealth of function libraries and function blocks (Functionblock), greatly reducing the workload of the development staff.


In the software development of PCC in this control system, we mainly adopt the programming mode based on C language and supplemented by ladder diagram. Due to the implementation of time-sharing multi-tasking, we divide the control requirements into the following parts:


(1) Temperature control (C language) The PIDxh function can be used to control the infinite temperature adjustment. In this system, 10 to 12 channels of temperature control are generally controlled. Since the C language is used, we can dynamically define how many temperature controls are currently available.


(2) Inverter communication control (C language) uses FrameDriver to write communication protocol with Fuji inverter. In fact, since FrameDriver is a free communication protocol, any brand of inverter communication protocol can be written on any serial interface (such as RS232, RS485/422, TTY, etc.); similarly, this also applies to the communication interface. Smart Meter.


(3) Auxiliary machine control (ladder diagram) controls the movement of mechanical devices such as cutting machines, tractors, and vacuum tables.


(4) Data block control (C language) stores various system parameters.


(5) Fault detection and alarm (C language) detects faults in operation, protects machinery, and provides various alarm modes.


The programming of the host computer adopts VB language. VB is a visual programming language with a large number of controls that can be used, so it is easy to develop a human-machine interface like a trend graph. The communication between the upper and lower computers depends on the B&RPVI protocol. B&R provides a communication control PVIControl.ocx. Simply insert the control into the VB program, create an instance of the control on the Form and define a variable correspondence table to access all the variables in the PCC. Due to the requirements of factory management, it is necessary to record various data in the production process, such as parameters, shift number, alarm record, motor current, heating current, etc., and save the above data for several months. Therefore, we have adopted Access the natural mdb database and read and write via ODBC. The database can be recalled and innately available for analysis by the manufacturer.


2.2 Intelligent implementation


For the intelligence of the control system, it is manifested in the following aspects:


(1) Adaptive function


The control of the extruder requires a variety of parameters (such as temperature setting, speed setting, etc.) and plays a decisive role in the control effect.


The setting of these parameters often requires the skill of manipulating the accumulated experience of the staff. Therefore, we use the self-learning function in the software, which can automatically or manually record the parameters required by the system under different time periods, different raw materials and different molds. It can be stored in the data module of PCC and can be called at any time. It can also be set manually. To automatically control from heating to holding to extrusion. Due to the variety of heating or cooling methods of the extruder (such as heating coil or core temperature heating, air cooling or oil cooling), ordinary temperature control table or PID regulator is difficult to perform proper temperature control; and B&R intelligent temperature PIDxh The software can automatically calculate the PID parameters required for different temperature control, so that the temperature control is accurate to ±1 °C.


(2) Fault detection and alarm function


In the normal production process, if you encounter a fault, you need to deal with it in time. Traditional control systems are unable to display the cause of the failure and are therefore difficult to repair. In this system, everything is very easy. The alarms in the extruder are roughly divided into: temperature alarm, inverter or motor alarm, mechanical action alarm. Since the temperature control uses centralized software control, it can directly display the actual temperature and set temperature on the man-machine interface to alarm the over-temperature or low temperature; at the same time, the control system monitors each heating unit for reporting at any time. Abnormal state of heating. The control of the inverter adopts RS485 bus mode, so it can directly read the alarm status when the inverter is faulty and can be directly reset on the man-machine interface. At the same time, it is also possible to determine the mechanical failure of the setting table, the traction cutter, etc. through the limit switch or the contact. All alarms can be recorded and saved for later viewing, and the system can automatically respond differently depending on the fault level. Therefore, in the event of a failure, the operator can query the cause of the fault from the HMI and immediately process it.


(3) Self-protection function


In order to operate the extrusion performance safely, it needs to be fully protected. Typically, the main screw is prohibited from starting when the temperature does not reach the set value and the holding time is insufficient.


(4) Hierarchical governance function


In the man-machine interface, different manipulation objects can have different manipulation authority by code and password, and record the behavior of the operator. Therefore, the manipulative authority of the worker is different from that of the technical staff, and the manufacturer may have a higher level of authority. The advantage of this is to reduce human interference, prevent unnecessary troubles caused by mishandling and manage the operator.


(5) Remote diagnosis and network function (optional)


In order to provide technical support to the ultimate user in time, B&RPCC can conduct remote online diagnosis and provide corresponding solutions through telephone lines and modems. With the scale of production, many customers need network management and remote control of multiple extruders. The B&RPCC promises to connect to the computer via Ethernet and can read the current status of each line on the terminal computer of the office or even directly control the production line to realize the integration of management and control.


(6) Database function


Thanks to the use of the industrial computer, it is possible to record data parameters, automatically generate data reports and summarize them through the network to strengthen production management.


(7) Easy to operate


Although the control system has such powerful functions, the user-friendly interface design, the fair button layout and rich online help make the operation very easy.


3 conclusions


Compared with the traditional PLC, it is very difficult to achieve the above various functions. The system's leading position in B&RPCC technology and Futian's years of experience in the plastics industry enable the control system to be developed in a short period of time. The system not only achieves international leading level in control functions and control accuracy. It is also one step ahead in the management of intelligentization, providing conditions for the profile manufacturing enterprises to achieve factory automation.

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