How big is the impact of the “machine brain” on CNC machi
source：未知
To understand the impact of the CNC system on CNC machine tools, we must first understand the structure of the CNC system. The numerical control system is mainly composed of human-computer interaction interface + numerical control core + programmable logic controller + driver, in which human-computer interaction interface is used for human-computer interaction; numerical control core is the core of numerical control system, used for calculation of trajectory, position Adjustments, and related controls such as acceleration, tool data, zero offset, and various complex machine functions. The programmable logic controller is used for the control of the machine logic, such as the tool magazine, hydraulic equipment, etc. The drive is the actuator, which adjusts the current loop and speed loop of the motor so that it can quickly and accurately complete the commands issued by the CNC core. .
CNC system is not only an accessory for CNC machine tools, but also a complete solution, which includes hardware and software, only when it is combined with software and hardware, and human-computer interaction interface in CNC system, CNC The core, programmable logic controller and drive cooperate to complete the control of the machine tool to ensure the high precision and high quality of the machine tool. Therefore, the quality of the CNC system will directly affect the accuracy and efficiency of the CNC machine.
In general, the “good CNC system” defined by Volkswagen will be equipped with high-end servo motors. A good CNC system can provide a variety of types of motors for users to choose, such as high dynamic motors, large inertia motors. Users can select motors with different characteristics according to different requirements of the machine. A good servo motor will generally have a higher encoder resolution. The higher the resolution, the smaller the speed fluctuation. Motors with high-resolution encoders will be more stable and more precise.
As everyone in the industry knows, there will be many elastic connections between the motor and the machine (such as elastic couplings). After a series of elastic links, the machine will have slight errors in the transmission process, and the system only knows the feedback of the motor. The error in the drive is not known, so the actual control accuracy will be affected by this. In response to this situation, the high-end CNC system can be connected to the grating scale as a direct measurement system to form a "full-closed loop", so that the system can directly control and adjust the mechanical feedback through the grating scale to improve the machine tool. Precision.
Today, many high-end CNC systems have been able to achieve more than half of the calculation accuracy. This also means that high-end CNC systems can provide higher control accuracy to achieve a better interpolation trajectory. Not only that, the machine tool will inevitably be affected by the vibration caused by the external environment during the production process, such as cooling equipment, hydraulic equipment, or other machine tools. This type of problem can generally be detected by the grating scale to detect the interference, but it is difficult to suppress and eliminate by adjusting the dynamic response parameters of the machine. High-end CNC machine tools can often suppress external interference by the same method as the advanced positioning control function of Siemens APC (Advance Position Control), thereby further improving the machining performance of the machine.
I remember when interviewing Mr. Li Jinhe, the assistant to the president of Yamazaki Mazak (China) Co., Ltd. at CCMT2018, he once said that the human-machine dialogue function of the seventh-generation CNC system has developed over the past 20 years and is now showing its superiority. The practical performance, in today's computer is so developed, many CNC equipment needs people to control, and Mazak's control system can edit the program through daily conversational language, which not only provides convenience for users, but also The production costs of personnel are largely saved. From this point of view, the high-end CNC system has demonstrated its exceptional superior performance.
Although the core of CNC machine tools lies in the machine tool itself, good mechanical performance is the basis, but a good, high-quality CNC system can make the machine's excellent mechanical performance more vivid, and achieve the goal of icing on the cake.
