Computer numerical control technology:
Summary: With the rapid reduction of the cost performance of computer hardware and the popularization and application of graphic display, modern CNC system no longer needs punched paper tape, but is directly controlled by computer, CNC for short. It uses a small general-purpose computer or personal computer to directly control a machine tool, and the control program of the machine tool is stored in the memory of the computer, which is easy to modify and expand its functions and has good flexibility.
Composition: Computer numerical control system consists of hardware and software, and the understanding of the architecture of numerical control system should be carried out from both hardware and software. Its core is computer digital control device. Through the system control software and system hardware, it reasonably organizes and manages the input, data processing, interpolation and output information of the numerical control system, controls the executive parts, and makes the numerical control machine tool automatically process according to the requirements of the operator. The CNC system takes the computer as the control component, and usually some or all CNC functions are realized by the CNC system software residing in it, so as to control the movement of the machine tool in real time. As long as the control software of computer numerical control system is changed, a brand-new control mode can be realized. There are many types of CNC systems, including lathes, milling machines and machining centers. The CNC system of various CNC machine tools generally includes the following parts: CPU, ROM/RAM, I/O devices, operation panel, display and keyboard, paper tape punch, programmable controller, etc.
Function:
In order to give full play to the potential of the computer, the function of modern CNC system is far from just completing the basic linear and circular interpolation calculation, but it is equipped with a large number of special software, which can complete many tasks, some of which are impossible or difficult to complete by traditional CNC. The following describes the main functions that modern numerical control systems usually have.
(1) axis control can control 3, 4 and 5 axes simultaneously. It can achieve higher cutting speed and processing quality.
(2) Tool Offset Compensation Modern CNC systems often have the function of tool radius compensation in three-dimensional straight lines.
(3) Programming function system provides some programming functions. Usually, the color graphic display terminal of the system can be used to manually compile the processing program of plane contour parts composed of straight lines and circular arcs, and the system is equipped with software to automatically calculate the intersection and tangent points of contours.
(4) Parallel operating system can realize two working modes in parallel: machine tool control mode and programming mode.
When the system is controlling the machine tool to process a part, the operator can complete the manual programming work with the keyboard at the same time, or input external programs or edit and modify existing programs through the data transmission interface. When the machine tool is machining, the graphic display terminal can simulate the execution of another machining program at the same time for inspection and editing.
(5) Tool Management and Monitoring Modern CNC machine tools are developing to machining centers. Usually, milling and boring machines have dozens of tool depots, and turning centers often have tool depots. Numerical control system has the function of controlling and managing tool magazine. Tool replacement is controlled by the numerical control system according to the program, and the tool is automatically replaced on the processing machine tool.
(6) The feed speed control performance of the high-speed and low-speed feed control system for machine tool moving parts is an important performance index of the numerical control system. Modern numerical control system can control the cutting motion of machine tools at a fairly high feed rate in a very short distance. This is very beneficial to the machining of curved surfaces, which can greatly shorten the machining time, especially for the transition zone with large curvature change, and still obtain good machining quality.
(7) The electronic contact alignment system provides a three-dimensional measuring contact (similar to a measuring probe), which is very convenient for aligning the workpiece.
(8) Physical measurement and automatic generation of processing program Physical objects (samples to be copied) can be scanned and measured with the above three-dimensional electric probe. The system automatically collects measuring point data, and the distance between points is related to the scanning speed. The scanning point data automatically generates a linear interpolation NC program through the interface, which can be executed without any post-processing.
(9) The execution of external programming and DNC operating system are usually equipped with standardized data communication interfaces, which can accept external programs, such as machining programs output by CAD/CAM system. For short programs, they can be stored in the warehouse; Long programs for machining complex surfaces can be input into the system in blocks and executed synchronously. This ensures that the system can adapt to the DNC operation mode controlled and managed by other computers.
(10) Portable electronic manual manipulator system usually provides portable electronic manual manipulator. The operator can use it to sensitively adjust the movement of the moving parts of the machine tool in the clearest and most convenient place, and its control range is 0.02 ~ 20 mm