On high-speed CNC machining technology and application analysis

Paper Keywords: high-speed cutting application of key technologies

Abstract: This paper systematically describes the high-speed CNC machining of the basic theory and the development process, analyzing the advantages and high-speed machining applications, summarizes the development of high-speed CNC machining needs of key technologies and research directions.


CNC high speed machining technology (High Speed ​​Machining, HSM, or High Speed ​​Cutting, HSC), is to improve the processing efficiency and processing quality of advanced manufacturing technologies, related technology research has become an important field of advanced manufacturing technology research directions. China is a manufacturing country in the world to try to accept the transfer of industries in the front instead of back-end of the transfer, that is, to master the core technology of advanced manufacturing, or in the new round of international industrial restructuring in China's manufacturing Industry will be further behind. research of advanced technology theory and application is imminent.

1, the meaning of CNC high speed machining
High-speed cutting theory by the German physicist Carl.J.Salomon beginning in the 1930s made through his large number of experimental studies have concluded that: in the normal range of cutting speed, cutting speed if improved, would result in cutting temperature rise, thereby increasing the cutting tool wear; However, when the cutting speed to a certain value, as long as more than the turning point, with the cutting speed, cutting temperature will not rise, but will drop, so long as the cutting speed is sufficient high, can be a good solution to cutting tool wear caused by high temperature is not conducive to cutting problem, get a good processing efficiency.

With the manufacturing Industry, this theory gradually being taken seriously, and has attracted attention of many researchers, on the basis of this theory gradually formed a high-speed CNC machining technology research, CNC high speed machining technology research in developed countries, relatively early, through the theoretical basic research, applied basic research and applied research and development applications, in some areas has entered a substantive application stage.

On high-speed machining areas, generally have the following classification methods, one based on cutting point of view, that the cutting speed is 5-10 times more than conventional cutting speed cutting. Some scholars to define the spindle speed as high speed machining standard that is higher than 8000r/min Spindle speed is high speed machining. well designed from the perspective of the machine spindle to spindle diameter and spindle speed DN define the product, if the DN value to (5 ~ 2000 × 105mm.r/min , is considered to be high-speed machining. production practices, processing methods, different materials, different high-speed cutting speed corresponding generally believed that the turning speed (700 ~ 7000m/min, milling speed (300 ~ 6000m/min, namely, that high-speed cutting.

In addition, from the practical considerations of production, high-speed machining concept not only includes the high-speed cutting process, also includes process integration and optimization, which is a good cost-effective high-speed access to the cutting process, the technology and effectiveness.

High-speed cutting technology is the machine structure and materials, machine design, manufacturing technology, high-speed spindle system, fast feed system, high-performance CNC system, toolholder system performance, high-performance cutting tool materials and tool design and manufacturing technology, high-precision measurement test technology, high-speed cutting mechanism, high-speed cutting process, and many other related hardware and software technologies are fully developed from the basis of comprehensive, therefore, high-speed cutting technology is a complicated systematic project, a development with the continuous development of related technologies concept.

2, the advantages of CNC high speed machining
Because of the substantial increase in cutting speed, high-speed machining techniques not only improve the machining productivity, and compared to conventional cutting also has some obvious advantages: first, the cutting force is small: in the high-speed milling, using a small amount of cutting high cutting speed the cutting form, the cutting force lower than 30% over conventional cutting, in particular, the spindle bearings, cutting tools, workpiece by radial cutting forces drastically reduced. not only to reduce tool wear, and effective control of the processing system vibration will help improve the precision and secondly, material removal rate: high-speed cutting, cutting speed and feed rate are greatly improved, the same time, the material removal rate is greatly increased accordingly, thereby greatly improving the processing efficiency. No. Third, the workpiece thermal deformation: high-speed cutting, cutting most of the heat was high time to pass out of the workpiece chip away, so the processing of the surface of the heating time is short, not because of temperature lead to thermal distortion, help to improve surface accuracy, surface finish of the physical and mechanical properties better than the normal processing methods. Fourth, the high precision: high-speed cutting feed rate is usually relatively small, so that machined surface roughness greatly reduced, and because the cutting force is less than the conventional cutting processing system to reduce vibration, the process is more stable, so that can get good quality, high accuracy, low roughness processing. Fifth, green: high-speed cutting, the machining time, energy and equipment utilization, and processing efficiency, processing and low energy consumption, and because high-speed cutting dry cutting can be achieved, even without cutting fluid to reduce, reduce pollution and energy consumption.

3, CNC high-speed cutting technology research in the field
Given the above characteristics of high-speed machining to make the technology areas of weakness in the traditional process has great potential applications. First, for thin wall parts and thin parts, high-speed cutting, cutting dramatically reduced, heat is chip away, you can make good use of traditional methods because the impact of cutting force and cutting heat caused by the deformation of problems, greatly improving the processing quality. Second, the cutting resistance is small, slow tool wear, high manganese steel, hardened steel, austenitic stainless steel, composites, cast iron and other traditional methods are difficult to machine materials, can be studied using CNC cutting technology to process high-speed addition, in the automotive, tooling, aerospace and other manufacturing areas, some components require a relatively large overall material removal rate, as high-speed CNC cutting feed rate can be increased with a corresponding increase in cutting speed, making unit time of the material removal rate greatly increased, and thus in the mold manufacturing, automobile manufacturing, aerospace manufacturing, CNC high-speed cutting technology will have enormous economic benefits. Fourth, as the high-speed cutting, the process smooth, little vibration , compared with conventional cutting, high-speed cutting can significantly improve the precision 1 to 2, completely abolished the subsequent finishing at the same time, the use of CNC high-speed cutting technology to a single machine to achieve the overall structure of complex parts at the same time rough and finish, reducing the transfer process may be the positioning error, and thus help to improve the machining accuracy, therefore, high-speed cutting precision manufacturing technology has broad application prospects, such as a company processing aluminum mold, mold cavity up to 1500mm, required dimensional accuracy error of +-0.05mm, the surface roughness Ra0.8μm, the original manufacturing process as follows: coarse planing - semi-fine plane - fine planing - scraping by hand - hand-polished, the manufacturing cycle to 60 hours. high-speed milling, after semi-finishing and finishing, processing cycle only six hours, not only efficiency, but also greatly improve the quality of the mold.

Links to free download http://www.hi138.com 4, to achieve high-speed CNC machining of key technologies
CNC high speed machining is a complicated systematic project, involving the cutting mechanism, cutting tools, cutting tools, cutting process monitoring and processing and many other related hardware and software technology, CNC high-speed cutting technology implementation and development depend on this system. the various elements, these high-speed cutting technology is inseparable from NC key technology embodied in the following areas:
1 high-speed cutting mechanism: For a variety of materials in high-speed processing conditions, the chip formation mechanism, cutting force, cutting heat variation, the law of tool wear on surface quality and the impact of law on the basis of the above theory, experiments and research, will help to promote high-speed cutting process and cutting specifications to determine the choice of specific parts and materials to provide a theoretical basis for the development of processing technology, principles of technology are present, black metal and high-speed cutting of difficult materials and cutting the amount of process specifications sure, high-speed cutting production difficulties, the high-speed machining research in the field of focus.

2 high-speed cutting machine tool technology module: high-speed cutting tools require high-speed spindle system, fast feed system and high speed CNC control system, high speed machining spindle unit required to work at high speed, usually spindle speed 10000 r / min or more, and some even up to 60000-100000r/min, and ensure good performance of the dynamic and thermal state which is a key component of the spindle bearing, spindle speed which determines the life and load capacity, high-speed cutting machine is one of the core components of the spindle structure improvements and Performance improvement is an important element of high-speed machine tool technology. Another important cell technology is the high-speed feed system with the spindle speed increases, each tooth to ensure the tool or the same amount of feed per revolution, the machine feed rate and feed acceleration have been increased, while speed of air travel have increased, so the machine feed system must be fast moving and fast and accurate positioning, which is obviously the Machine Tool, servo system, proposed a new table structure higher demands, high-speed machine tool technology is the key to restricting cell technology.

3 high-speed cutting tool technology modules: from the machine, tool and workpiece composed of high-speed machining technology systems, the tool is the most active factor cutting tools to ensure smooth high-speed machining technology, the most critical one with the cutting speed substantial increase of the cutting tool material, tool geometry, tool body structure and so made differs from traditional requirements of cutting speed, high-speed cutting tool material and tool manufacturing technology have undergone great changes, high-speed machining, to to ensure high productivity and precision, but also to ensure safe and reliable. Therefore, high-speed cutting tool system must meet the good geometric accuracy and high clamping repeatability, clamping stiffness, high-speed running good balance and secure as much as possible to reduce the quality of the tool body to reduce the high-speed rotation when the subject of centrifugal force, to meet the security requirements of high-speed cutting, improved tool clamping. tool system technology research and development is the key to high-speed CNC machining tasks.

4 high-speed CNC machining technology: high-speed cutting as a new cutting method to be applied to actual production, the lack of reference of the application instance, and no practical cutting and machining parameters database, high-speed machining process parameters to optimize the current constraints One of the key technologies of its application. Also, high-speed cutting of parts required NC program must ensure that the load throughout the cutting process stability, but now most of CNC software using the automatic programming functions can not meet this requirement, which requires be supplemented and optimized manual programming, which to some extent, reduce the value of high-speed cutting, must study a new way of programming, the cutting data for high-speed spindle power curve, give full play to the advantages of CNC high-speed cutting.

High-speed machining technology and application depends on the above principle, the machine tools, cutting tools, technology and other key cell technology development and integration.

5, high-speed cutting technology applications research status and development trends
As high-speed cutting in improving production efficiency has great potential, early has become the United States, Japan, Germany and other countries competing for research in key technology areas. United States and Japan and other countries as early as in the early 1960s, began a study of the mechanism of high-speed cutting. On In the 1970s, the United States has developed a maximum speed of 20000r/min high-speed milling machine. Today, Europe and other developed countries produce different specifications of the various high-speed commercial production of machine tools and has to enter the market, in aircraft, automotive and mold manufacturing Industry practical applications, for example, in the U.S. aircraft manufacturer Boeing, etc., have adopted CNC high speed machining technology ultra high-speed milling aluminum alloy, titanium and other thin-walled structural parts and the whole waveguide, flexible top frame and other common methods difficult to machine parts In recent years, the United States, Europe, Japan and other countries for a new generation of CNC machine tools, high-speed machining centers, high-speed tool to study the system and to further accelerate the process of industrialization, high-performance spindle technology and its products, increase the pace of production specialization, high-performance tool system technology is progressing rapidly, linear motor technology for high-speed feed system.

Our research and development in high-speed cutting technology, the efforts of many universities and research institutes and exploration, including the cutting mechanism, tool material, spindle bearings, etc., have also made considerable achievements, however, compared with foreign industrial countries , there are still large gaps, basically still in the laboratory research stage. to meet the social and economic development needs to meet the aerospace, automotive, tooling and other manufacturing requirements of various industries, CNC high speed machining technology research long way to go.

Currently, the research for high-speed cutting technology from the experimental phase to the application stage in the application of research consists of two levels: first, high-speed processing of basic research of key technologies, including high-speed spindle unit and high-speed feed unit, etc., to achieve high-speed localization of machine the other hand, in the existing laboratory technology practice, based on the process performance and the scope of application of technology which, the research on high-speed cutting technology is currently one of the most active areas of research, the main objective is to test or the introduction of advanced technology equipment directly to research efforts to address the key components of the processing problems, develop and improve high-speed cutting of special materials, process methods, research and development for high-speed processing of CAD / CAM software systems and after-treatment system, based on new detection technology based on the processing status of safety monitoring system.

References
[1] H. Schulz a, Overview of high speed machining, Wang Chih-kang translation, machine manufacturing and automation [J] .2002 (1.

[2] Sun Wencheng high-speed machining of mold key technologies [J] .- Machinery Manufacturing and Automation 2008 (5).

[3] Ai Xing, high speed machining technology [M]. Beijing: National Defence Industry Press, 2003.

[4] Liu Zhan-Qiang, high-speed cutting technology research and application of [D]. Shandong University doctoral thesis, 2001.

[5] Zhang Yaqiong, thin-walled parts lathe fixture design [J]. Chinese high-tech enterprises, 2010 (8 Links to free download http://www.hi138.com