| The structure of injection molding machine determines the discrete distribution of itselectrical components and local concentration of its main control box. It is the far-linetransmission of IO signals that is important factor that influences the precision of injectionmolding machine. At the same time, control accuracy is to a great extent related to theposition signal and the temperature signal acquisition precision. So the ways picking up thekey signals using special chips and anti-interference measures are taken as the effectivemeans to improve the control precision. At present, there is a big gap between the domesticinjection molding machine controllers and foreign products on the control accuracy. Foreignadvanced controller is generally designed and developed based on the deep understanding ofthe characteristics of the injection molding machine. Some famous vendors, such as B&R,Gefran, have designed some controllers dedicated to injection molding machine which adoptsdistributed structure design, and use high performance chip to realize the collection of the keysignal. While domestic controllers basically all are common central integration type. So, forimproving the injection molding machine control precision, how to obtain technologybreakthroughs in architecture design, signal acquisition, anti-jamming and real-timecommunication and so on has become the focus of current research.According to the characteristics of the injection molding machine, a design scheme ofcentralized distribution controller based on ePLC is presented in this paper. The controllercan be divided into main control module, digital I/O module, temperature acquisition module,temperature output module, electronic ruler signal acquisition module, analog signal outputmodule, etc. The communication between modules is realized using the CAN field busprotocol. A method of remote transmission digitally is put forward in the design of thetemperature acquisition module and electronic ruler signal acquisition module, which is topick up and process analog signals on the spot, and to transfer data in the form of digitalsignal to the main controller through CAN bus, avoiding the signal is interfered in the processof the long transmission in the form of analog.In the temperature control and motion control of injection molding machine, intelligentcontrol algorithms are common adopted. For implementation of complex algorithm, highprocessor speed is needed to achieve good real time response. In the design scheme, atwin-engine architecture design method is proposed. Based on TI new Concerto dual-coremicrocontrollers, the tasks of communication management and logic process control are realized by ARM-side engine in the ARM kernel, while the execution of algorithm isimplemented in DSP-side engine in the DSP kernel. Two kernels can be executed in parallel.Algorithm implementation will not affect system response time. The scheme also designs thecommunication interface between the dual-core, realizes the mutex and synchronizationbetween the dual-core. The design method support synchronous development of dual coreengine, significantly reducing the development cycle. And engine is realized based on CASSdevelopment platform, supporting the field programming.Experiments show that this controller simplifies the electrical wires. The acquisitionprecision of temperature signal and the electronic ruler signal has reached±0.01mm.Position control accuracy is to±0.03mm and the temperature control precision is to±1℃.The result meets the design requirements. |
