What are the six main features of CNC precision machining?
发布日期：19年05 月02日 Source: Jindong Metal Products Release Date: May 02, 19
CNC precision machining is in development and currently has the following characteristics.
(1) The formation of systems engineering precision machining and ultra-precision machining is a multi-disciplinary comprehensive advanced technology. To achieve high precision and high surface quality, not only the machining method itself must be considered, but also the material being processed, processing equipment and process equipment , Detection methods, working environment and human skills. Therefore, the isolated processing method cannot achieve the intended effect, and must be supported by comprehensive technology and conditions, thereby forming a precision processing system engineering. The combination of precision machining technology with system theory, methodology, computer technology, information technology, sensor technology, and digital control technology has further contributed to the formation of precision machining system engineering. While studying the theories of precision machining and ultra-precision machining, the mechanism of surface formation, and establishing mathematical models, we must also study related technologies.
(2) Precision processing and ultra-precision processing are closely related to micro-processing and ultra-fine processing. Micro-processing and ultra-micro-processing refer to the production and processing technology of manufacturing micro-sized parts and ultra-micro-sized parts. The emergence and development of microfabrication and ultra-microfabrication are closely related to integrated circuits. Integrated circuits require the manufacture of more elements on semiconductor material chips with small areas to form circuits of various complex functions. Therefore, the number of unit logic gate circuits on the unit chip, the number of sub-components on the unit chip, and the minimum line width are signs of the integration of the integrated circuit, and they also indicate its manufacturing difficulty and level. The table lists the parameters and performance of small, medium, large, and ultra-large-scale integrated circuits.
The concept and mechanism of microfabrication and general dimensional processing are different. In general dimensional processing, accuracy is expressed in tolerance units. Tolerance = tolerance grade factor x tolerance unit. The same accuracy has the same tolerance grade factor, but the tolerance unit As the size of the basic size is different, the larger the basic size, the larger the tolerance unit. There are different formulas for calculating the range of the basic size. When the surface is finely machined, the accuracy is expressed by the absolute value of the size because the machining size is small. This is because from a workpiece perspective, the biggest difference between general machining and micromachining is the size (thickness) of chips. During micro-machining, the amount of back-knife is extremely small. The cutting is performed inside the crystal of the material. The amount of cutting removal is expressed by the "processing unit size" or "processing unit". The size of the processing unit represents the level of processing accuracy, such as the molecule Level processing, atomic level processing. Although microfabrication and general size processing are different in concept and mechanism, from the perspective of processing technology, micromachining is mainly processing small sizes, while precision processing and ultra-precision processing both process large sizes. It also processes small sizes, so micro-machining belongs to the category of precision machining and ultra-precision machining. In fact, many of the machining methods are the same, but the processing objects are different.
(3) Precision processing and ultra-precision processing are closely related to special processing. Special processing refers to non-traditional processing methods that use mechanical, optical, electrical, acoustic, thermal, chemical, magnetic, atomic and other energy sources for processing, and has developed rapidly in recent years. , Not only can adopt a single processing method, but also can adopt a composite processing method, which is widely used. At present, many precision machining and precision machining methods use special processing techniques such as laser processing and ion beam processing, which have opened up new paths for precision processing and ultra-precision processing. Some high-hardness and brittle difficult-to-machine materials, such as quenched steel, hard Carbide alloys, ceramics, quartz, diamonds, etc., some parts with poor rigidity and easy deformation during processing, such as thin-walled parts, elastic parts, etc., in precision machining and ultra-precision machining, special machining is already necessary or even the only means , Formed a precision special processing.
At present, although the traditional processing method still occupies a large proportion and is the main processing method, it should be valued and further developed. However, due to the rapid rise of special processing, not only many new processing mechanisms have appeared, but also various composite processing technologies. Integrating several processing methods together, giving full play to their strengths and complementing each other, has great potential to improve processing accuracy, surface quality and efficiency, and expand the scope of processing applications.
(4) Machining and inspection The precision and surface quality of integrated precision machining and ultra-precision machining are very high. Therefore, there must be corresponding inspection methods to explain whether the technical requirements have been met. Therefore, in precision machining and ultra-precision machining, processing and inspection are difficult problems, and often the detection is more difficult. Only the integration of processing and inspection strategies is adopted, and inspection is considered while processing. From the analysis of the detection process, the detection can be divided into three categories: offline detection, in-place detection and online detection. Off-line testing refers to testing in the inspection room after processing is completed. Therefore, processing and testing are separated. If the testing fails, it is generally difficult to return for repair because of high processing accuracy. In-place inspection refers to that the workpiece is not unloaded after the processing is completed, and the inspection is performed on the machine tool. If the inspection side is unqualified, it can be repaired in time without causing errors caused by re-clamping during rework, but it is necessary to consider offline inspection and in-place inspection. The impact of the test on the test results due to differences in the test environment. On-line detection is a real-time detection during the processing process. It is a dynamic detection process to grasp the processing error value and its development trend at any time and perform real-time control.
Error compensation is an effective technical measure to improve machining accuracy. It can be divided into two categories: static error compensation and dynamic error compensation. Static error compensation is mainly used to compensate system errors in process systems, such as error correction rulers. Dynamic error compensation is real-time compensation during processing, which can compensate for random errors and system errors in the process system. Dynamic error compensation and online detection are closely related.
The development of numerical control technology, computer control technology, sensor technology, and micro-displacement mechanism has enriched error compensation methods, and in particular, has made great progress in online detection and dynamic error compensation. In precision machining and ultra-precision machining, inspection and error compensation are important measures for the integration of machining and inspection.
(5) Precision machining and ultra-precision machining are closely linked with automation technology. Manufacturing automation is an important part of advanced manufacturing technology. Its role is not only to improve efficiency, improve labor productivity, improve the working environment and workers' labor conditions, but also improve processing accuracy. And surface quality, to avoid human error caused by manual operation, to ensure the processing quality and stability of the intended measures. At the same time, it is a powerful measure to quickly respond to market demand and shorten the production surplus cycle. To achieve high quality in precision machining and ultra-precision machining, automation technology can guarantee it. Technologies such as process optimization and adaptive control, detection and error compensation, and computer control are all automated technologies that improve and guarantee processing quality. Although the quality of precision machining and ultra-precision machining still depends on the skills of workers, such as grinding, scraping and other processing methods still rely on manual, but from the development trend, the proportion of automation technology to replace manual is increasing Larger, the processing effect is getting better.
(6) The development of precision machining and ultra-precision machining is closely linked to product needs. Precision machining and ultra-precision machining require high processing quality, are technically difficult, involve a wide range, and have many influencing factors. Therefore, investment is often large. Therefore, the development of precision machining and ultra-precision machining is closely related to specific product requirements. For example, with the support of the Department of Energy, the Lawrence livemsr laboratory and the y12 factory at the University of California in the United States jointly developed the DM-3 ultra-precision diamond lathe in 1989, which is aimed at processing various mirrors and large celestial bodies for laser fusion. Telescope antennas, etc., reflect the needs of space technology. China's development of precision machining and ultra-precision machining technology is also combined with the specific needs of aerospace and aviation technology. At present, the standardization and series of precision machine tools and ultra-precision machine tools are far less than ordinary machine tools, and there are not enough varieties, mainly due to insufficient technical promotion, general versatility, and very expensive prices. With the expansion of market demand, With the improvement of product quality and the maturity of precision processing technology, generalized and serialized sugar dense processing and ultra-precision processing equipment will surely be more widely used in production practice.