In the 21st century, the fierce market competition promotes the development of advanced manufacturing technology with machine manufacturing technology as the guide at an unprecedented speed, and the manufacturing of aviation parts has also entered a period of development characterized by digital manufacturing technology. According to the editor of Huicong surface treatment network, advanced aviation products require aviation parts to have better performance, lower cost and higher environmental protection, while the processing technology requires faster processing speed, higher reliability, high repeatability and reproducibility. The traditional tool can not meet the above requirements, so the tool industry has entered a new pattern of modern tool production with "high precision, high efficiency, high reliability and specialization.
High-speed, high-efficiency cutting
With the advancement of science and technology, we are in a period of rapid development of advanced manufacturing technology. The promotion and application of CNC machine tools has greatly reduced the auxiliary time for parts processing and greatly improved productivity. In the total working hours of aviation parts processing, the auxiliary time is shortened, and the proportion of cutting time is correspondingly increased. In order to further improve the productivity of machine tools, the cutting speed must be greatly increased, which is also the rapid development of high-speed cutting technology in recent decades. The main reason. High-speed processing is mainly used for the processing of light alloys in the aviation industry, and has become the main way for the aviation manufacturing industry to improve processing efficiency and quality and reduce processing costs.
In aviation parts processing, high-speed cutting is being widely used, mainly for the following reasons:
(1) In order to maximize weight reduction and meet other requirements, many components, panels, etc. use the "overall manufacturing method", that is, in the large blank to remove the allowance, the formation of thin-walled, thin-rib structure parts, need to remove a large number of metal materials, resulting in cutting time to occupy a large proportion of the total production time of parts, so one way to improve productivity is to use high-speed cutting.
(2) aircraft parts of the complex structure, high precision, thin-walled parts, thin rib structure stiffness difference, to minimize the processing of radial cutting force and thermal deformation, only the use of high-speed machining to meet these requirements.
(3) Difficult to process materials, such as nickel-based high-temperature alloys, titanium alloys, and high-strength structural steels, are widely used in modern aviation products. These materials have high strength, high hardness, impact resistance, easy hardening during processing, high cutting temperature, and serious tool wear. It is a difficult-to-process material. Generally used very low cutting speed for processing, if the use of high-speed cutting, not only can greatly improve productivity and can effectively reduce tool wear, improve the surface quality of parts.
High-speed machining is different from the traditional cutting technology processing mechanism and application advantages, it is a change in the concept of CNC machining process. According to the material and structural characteristics of aviation products, high-speed machining must be guaranteed by advanced high-speed cutting tools. High-speed cutting tools must have good wear resistance and high strength toughness, advanced tool materials, excellent tool coating technology, reasonable geometric structure parameters, highly dynamic balance tool system, safe and reliable clamping method, and high concentricity of the blade accuracy and so on.
Development Direction and Application of Cutting Tool Materials
At present, in the field of aircraft manufacturing, high-speed steel tools account for about 6% of the total cutting tools, hard alloy tools account for about 35% of the total cutting tools, and superhard tools (cubic boron nitride and diamond) account for no more than 5% of the total cutting tools. In the future, with the continuous emergence of new aviation materials, the application of hard cutting and dry cutting will increase, the proportion of carbide tools, coated tools, ceramic tools, cubic boron nitride tools and polycrystalline diamond tools will be greatly increased.
1. Development of cemented carbide materials
In order to meet the rapid development of high-speed cutting technology, the performance of various cutting tools based on cemented carbide has been comprehensively improved. The development of fine particles and ultra-fine particles of cemented carbide and the application of coating technology on cemented carbide tools have significantly improved the strength and toughness of cemented carbide materials, it lays an important foundation for the popularization and application of high-speed cutting. The whole cemented carbide has also been applied in some complex forming tools to meet the needs of product processing diversity. At present, Xiamen Jinlu Special Alloy Co., Ltd., Zhuzhou Diamond Hard Cutting Tool Co., Ltd., Siping Bolt Process Equipment Co., Ltd. and Shaanxi Aviation Cemented Carbide Tool Co., Ltd. can provide cemented carbide tools for the aviation industry, and its product performance is close to the world's advanced level.
In the 21st century, cemented carbide tool materials should focus on two aspects of development: one is to refine the grain to reach the nanoscale microcrystalline level. The smaller the grain size of cemented carbide, the higher the hardness of cemented carbide, the better the wear resistance, the higher the toughness and stiffness, thus expanding its application range; the second is the application of new technologies and new processes to develop new cemented carbide to improve the intrinsic performance and quality of cemented carbide.
2. Development of coating technology
Tool coating technology plays a very important role in modern cutting and tool development, since its inception has developed very rapidly, especially in recent years has made significant progress, chemical coating (CVD) is still the main coating process of indexable inserts, successively developed new processes such as medium temperature CVD, thick film alumina, transition layer, etc., on the basis of the improvement of the substrate material, so that the wear resistance and toughness of CVD coatings have been improved; the physical coating (PVD) technology has also made major breakthroughs, and has made significant progress in the structure, process, and automatic control of coating equipment. It has developed heat resistance for high-speed cutting, dry cutting, and hard cutting. Better coating, through the innovation of coating structure, a large number of new coatings such as nano and multilayer structures have been developed, which greatly improves the hardness and toughness of the coating.
3. Development of superhard tool materials
Superhard materials refer to diamond and cubic boron nitride (CBN), whose hardness is several times higher than other tool materials. Diamond is the hardest substance in nature, and the hardness of CBN is second only to diamond. In recent years, superhard tool materials have developed rapidly.
Diamond tool materials are divided into 5 categories: natural diamond (ND), synthetic polycrystalline diamond compact (PCD/CC), diamond thin film coated tools (CD), diamond thick film tools (FCD) and synthetic polycrystalline diamond (PCD). ND crystal anisotropy, in the use of knife grinding must choose the appropriate direction; synthetic diamond isotropic, its hardness is lower than ND, but the strength and toughness is better than ND.
Diamond tools can effectively process non-ferrous metal materials and non-metallic materials. Such as copper, tungsten and other non-ferrous metals and their alloys, ceramics, cemented carbide, various fiber and particle reinforced composite materials, plastics, rubber, graphite, glass and wood, etc., but diamond avoid cutting steel and other iron group elements.
Cubic boron nitride (CBN) tool material has extremely high hardness and red hardness, is the ideal tool material for high-speed finishing or semi-finishing of hardened steel, chilled cast iron and high-temperature alloys. As CBN tools can obtain good surface roughness when machining high hardness parts, CBN tools can be used to cut hardened steel ".
4. Development of high speed steel materials
In the future development of tool materials, the development of high-speed steel materials should still be mentioned. Although the sales of high-speed steel materials in the world are decreasing year by year, the use of high-performance cobalt high-speed steel and powder metallurgy high-speed steel is still increasing. These two kinds of high-performance high-speed steel have better wear resistance, red hardness and reliability than ordinary high-speed steel. With the improvement of people's pursuit of cutting efficiency and the change of concept, these high-performance high-speed steel tools are widely used in the aviation field. Such as aviation difficult to process materials, automatic drilling and riveting machine used in drilling, reaming, countersink integrated high-precision composite tools and processing aircraft parts complex surface of various types of composite tools.
With the advancement of science and technology, advanced manufacturing systems, high-speed cutting, ultra-precision machining, and the development and implementation of green manufacturing, new requirements are put forward for tools, and tool materials will also have significant development in the future. The alternating development and mutual promotion of both tool materials and workpiece materials have become the historical law of the continuous development of cutting tools. In the future, tool materials will face more severe challenges in improving workpiece performance, increasing processing batches and improving manufacturing accuracy. The progress of materials science has promoted the development of tool materials, and the development of tool materials should consider the constraints of raw material resources. The emergence of new varieties, the change of the proportion of new and old varieties and the pattern of competition and mutual supplement between them will become the new characteristics of the development of tool materials in the future.