In 1952, MIT cooperated with Parsons and invented the world's first three-axis CNC milling machine. The control part consists of thousands of electron tubes. Its interpolation device uses pulse multipliers. The success of this machine tool marks the beginning of NC technology and a new era of machine tool manufacturing.
After the first CNC milling machine, with the development of electronic component technology, computer technology, and servo technology, the modern CNC system has been greatly improved in terms of function, performance, stability, and processing speed. As the core part of CNC machine tool control, CNC system plays a great role in the development of CNC technology. Its development is roughly the following:
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With the improvement of machining accuracy and speed, the functions of the NC system are required to be continuously expanded, improved and improved. In particular, high-speed, high-precision control systems are required to meet the requirements of high-speed and high-precision machining, including rapid input of programs and high-speed, high-precision interpolation. Make up, control and output. In addition, the simplification and improvement of the mechanical structure and the improvement of new processing functions require that the software functions of the NC become more and more complex. In addition, the continuous operation and coordination of mechanical processing require the continuous improvement of the reliability of the NC system. Processing and information systems can be controlled, processed, transmitted, managed, and shared via the network. It is because of the above reasons that the open NC unit based on PC-BASED has been widely used in the field of numerical control.
1. Open Numerical Control System The open system structure is defined as a module that allows multiple manufacturers to exchange and interoperate with each other in a competitive environment. Machine tool manufacturers can build their own control systems by adding certain hardware and software to the open system platform. At present, the more popular open CNC has two main structures: 1. CNC+PC motherboard: insert a PC motherboard into the traditional CNC machine, the PC board is mainly run non-real-time control, and the CNC mainly runs real-time control based on coordinate axes. . 2. PC+ Professional Motion Control Card: The motion control card is inserted into the computer's standard slot for real-time control, while the PC is mainly used for processing non-real-time control. In particular, Option 2, which can give full play to its fast computer processing speed and human-machine interface friendly features, is increasingly welcomed by machine tool manufacturers and has become the mainstream of open CNC development in China in recent years.
2. The hardware structure of open CNC system:
The following is an example of the MPC01 motion control card independently developed by Stepper Electromechanical Co., Ltd. This paper introduces the open CNC system of the “PC+ Professional Motion Control Card†structural model. The system adopts the master-slave control structure: in which the PC is responsible for the management of the human-computer interaction interface and the real-time monitoring of the control system (such as the display of system status, the sending of control commands, etc.); the lower position machine uses stepper The company MPC01 series motion control card is used to complete all the details of the control, including output of pulse and direction signals, processing of automatic lifting, detection of signals such as origin and limit, and so on. The CPU of the industrial control computer and the dedicated motion control chip on the MPC01 control card constitute the hardware structure of the dual CPU of "PC+MPC01". DOS or Windows is used as the operating system.
2.1 Control Methods and Features of MPC01 Series Motion Control Cards Step-Servo Co., Ltd. is a professional motion control company based on technology. It is one of the major manufacturers of domestic motion control cards. The MPC01 series sports cards use imported special chips, which are highly integrated and stable and reliable. At the same time, it is equipped with rich and powerful motion function library, which can be used in C/C++ or VB, etc. Called under the environment, it communicates with the computer through the bus. And because it uses the VXD virtual drive technology, it makes good use of the underlying Windows interrupt call, which enables real-time multitasking, which makes it greatly reduce the host and programming burden in both processing time and task switching. Improve the speed and control accuracy of the entire control system.
2.2 Control structure of the system The control system is based on the MPC01 of the industrial PC and uses the Panasonic digital AC servo system to form an open CNC system. The multi-axis motion control function of MPC01 is used to connect the AC servo system with the pulse output channel of the DMC to realize the output of the motor speed signal. At the same time, it can also accept the sampling of the feedback signal of the photoelectric encoder so as to achieve full-closed-loop control. In addition, through the DB15 interface of the DMC, it is possible to input some IO amount related to motion control on the receiver bed. Such as the detection of the machine origin, limit switch and other signals.
The motion control card must communicate with the PC to complete the control tasks of the machine tool. Through the peripherals of the PC, the input of the machining program, editing, setting of parameters, and the real-time status of the machine tool operation can be realized. In addition, the DNC function of the system can be easily realized by virtue of the powerful functions of graphic data processing of the PC.
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After the first CNC milling machine, with the development of electronic component technology, computer technology, and servo technology, the modern CNC system has been greatly improved in terms of function, performance, stability, and processing speed. As the core part of CNC machine tool control, CNC system plays a great role in the development of CNC technology. Its development is roughly the following:
With the improvement of machining accuracy and speed, the functions of the NC system are required to be continuously expanded, improved and improved. In particular, high-speed, high-precision control systems are required to meet the requirements of high-speed and high-precision machining, including rapid input of programs and high-speed, high-precision interpolation. Make up, control and output. In addition, the simplification and improvement of the mechanical structure and the improvement of new processing functions require that the software functions of the NC become more and more complex. In addition, the continuous operation and coordination of mechanical processing require the continuous improvement of the reliability of the NC system. Processing and information systems can be controlled, processed, transmitted, managed, and shared via the network. It is because of the above reasons that the open NC unit based on PC-BASED has been widely used in the field of numerical control.
1. Open Numerical Control System The open system structure is defined as a module that allows multiple manufacturers to exchange and interoperate with each other in a competitive environment. Machine tool manufacturers can build their own control systems by adding certain hardware and software to the open system platform. At present, the more popular open CNC has two main structures: 1. CNC+PC motherboard: insert a PC motherboard into the traditional CNC machine, the PC board is mainly run non-real-time control, and the CNC mainly runs real-time control based on coordinate axes. . 2. PC+ Professional Motion Control Card: The motion control card is inserted into the computer's standard slot for real-time control, while the PC is mainly used for processing non-real-time control. In particular, Option 2, which can give full play to its fast computer processing speed and human-machine interface friendly features, is increasingly welcomed by machine tool manufacturers and has become the mainstream of open CNC development in China in recent years.
2. The hardware structure of open CNC system:
The following is an example of the MPC01 motion control card independently developed by Stepper Electromechanical Co., Ltd. This paper introduces the open CNC system of the “PC+ Professional Motion Control Card†structural model. The system adopts the master-slave control structure: in which the PC is responsible for the management of the human-computer interaction interface and the real-time monitoring of the control system (such as the display of system status, the sending of control commands, etc.); the lower position machine uses stepper The company MPC01 series motion control card is used to complete all the details of the control, including output of pulse and direction signals, processing of automatic lifting, detection of signals such as origin and limit, and so on. The CPU of the industrial control computer and the dedicated motion control chip on the MPC01 control card constitute the hardware structure of the dual CPU of "PC+MPC01". DOS or Windows is used as the operating system.
2.1 Control Methods and Features of MPC01 Series Motion Control Cards Step-Servo Co., Ltd. is a professional motion control company based on technology. It is one of the major manufacturers of domestic motion control cards. The MPC01 series sports cards use imported special chips, which are highly integrated and stable and reliable. At the same time, it is equipped with rich and powerful motion function library, which can be used in C/C++ or VB, etc. Called under the environment, it communicates with the computer through the bus. And because it uses the VXD virtual drive technology, it makes good use of the underlying Windows interrupt call, which enables real-time multitasking, which makes it greatly reduce the host and programming burden in both processing time and task switching. Improve the speed and control accuracy of the entire control system.
2.2 Control structure of the system The control system is based on the MPC01 of the industrial PC and uses the Panasonic digital AC servo system to form an open CNC system. The multi-axis motion control function of MPC01 is used to connect the AC servo system with the pulse output channel of the DMC to realize the output of the motor speed signal. At the same time, it can also accept the sampling of the feedback signal of the photoelectric encoder so as to achieve full-closed-loop control. In addition, through the DB15 interface of the DMC, it is possible to input some IO amount related to motion control on the receiver bed. Such as the detection of the machine origin, limit switch and other signals.
The motion control card must communicate with the PC to complete the control tasks of the machine tool. Through the peripherals of the PC, the input of the machining program, editing, setting of parameters, and the real-time status of the machine tool operation can be realized. In addition, the DNC function of the system can be easily realized by virtue of the powerful functions of graphic data processing of the PC.
3. The software composition of the open CNC system:
This system gives full play to the advantages of rich PC software resources and fast data processing speed. It absorbs the features of CAD/CAM. After using the modeling software to generate the parts drawing, the graphics DXF format file is converted into a processing G code. Then, the G code is interpreted as the motion control function of the board, and finally the machine tool control is achieved by calling the interpolation motion function in the MPC01 motion function library.
4 Conclusion:
"PC + motion control card" type numerical control system will be a milestone in the open CNC system. This system supports the customization of motion control strategies and embodies a core level of openness. Starting from this system, the CNC system will enter the era of “completely openâ€.