May 07, 2021

Looking at the future market development of China's tool industry from the needs of aviation industry

Entering the 21st century, fierce market competition has driven advanced manufacturing technology pioneered by machine manufacturing technology to move forward at an unprecedented speed. The manufacture of aerospace components has entered a period of development characterized by digital manufacturing technology. According to the editor of HC Surface Treatment Network, advanced aerospace products require aerospace parts with superior performance, lower cost and higher environmental protection, while the processing technology requires faster processing speed and higher reliability. High repeatability and reproducibility. The traditional tool can no longer meet the above requirements, and the tool industry has entered a new pattern of modern tool production with high precision, high efficiency, high reliability and specialization.

High speed, efficient cutting
With the advancement of science and technology, we are in the period of rapid development of advanced manufacturing technology, the promotion and application of CNC machine tools, greatly reducing the auxiliary time of parts processing, and greatly improving productivity. In the total working hours of aerospace parts processing, the auxiliary time is shortened, and the proportion of time taken by the cutting is increased accordingly. In order to further increase the productivity of the machine tool, the cutting speed must be greatly improved. This is also the rapid development of high-speed cutting technology in recent decades. The main reason. High-speed machining was first used in the processing of light alloys in the aerospace industry. It has become the main way to improve processing efficiency and quality and reduce processing costs in the aviation industry.

In the processing of aerospace parts, high-speed cutting is being used in a large number of applications, mainly for the following reasons:

(1) In order to minimize weight loss and meet other requirements, many components, siding, etc. adopt the "integral manufacturing method", that is, to remove the margin on the large blank, to form thin-walled, fine-rib structure parts, which need to be removed. A large amount of metal materials, resulting in a large proportion of the total production time of the parts taken by the cutting time, so one of the ways to improve productivity is to use high-speed cutting.

(2) The structure of the aircraft parts is complex and high in precision. The thin wall and fine rib structure of the parts have poor rigidity. It is necessary to minimize the radial cutting force and thermal deformation during machining. Only high-speed machining can meet these requirements.

(3) Difficult-to-machine materials, such as nickel-based superalloys, titanium alloys, and high-strength structural steels, are widely used in modern aerospace products. These materials have high strength, high hardness, impact resistance, easy hardening during processing, high cutting temperatures, and severe tool wear. , belonging to difficult to process materials. It is generally processed at a very low cutting speed. If high-speed cutting is used, not only can the productivity be greatly improved, but also the tool wear can be effectively reduced and the surface quality of the part can be improved.

High-speed machining has different processing mechanisms and application advantages from traditional cutting technology. It is a change in the concept of CNC machining. According to the material and structural characteristics of aerospace products, high-speed machining must be ensured by advanced high-speed cutting tools. High-speed cutting tools must have good wear resistance and high strength and toughness, advanced tool materials, excellent tool coating technology, reasonable geometric parameters, highly dynamic tool system, safe and reliable clamping, and high concentricity. The accuracy of the blade and so on.

Development direction and application of cutting materials
At present, in the field of aircraft manufacturing, high-speed steel tools account for about 60% of the total cutting tools, and carbide tools account for about 35% of the total tool. Superhard tools (cubic boron nitride, diamond) account for The total amount of all tools is less than 5%. In the future, with the continuous emergence of new aviation materials, the application of hard cutting and dry cutting will increase. Carbide tools, coated tools, ceramic tools, cubic boron nitride tools and polycrystalline diamond tools will The ratio will increase significantly.

1. Development of cemented carbide materials
In order to meet the rapid development of high-speed cutting technology, the performance of various tool materials based on cemented carbide has been comprehensively improved. The development of fine-grained and ultra-fine particle cemented carbide and the application of coating technology to cemented carbide tools are significant. The strength and toughness of cemented carbide materials have been improved. The overall alloy tool made by it is gradually replacing traditional high-speed steel tools, which has improved the cutting speed and processing efficiency several times, laying an important foundation for the popularization and application of high-speed cutting. Solid carbides are also used in some complex forming tools to meet the diverse needs of product processing. At present, Xiamen Jinlu Special Alloy Co., Ltd., Zhuzhou Diamond Hard Cutting Tool Co., Ltd., Siping Bolt Craft Equipment Co., Ltd. and Shaanxi Aviation Carbide Tools Co., Ltd. can provide carbide tools for the aviation industry. Close to the world's advanced level.

The 21st century cemented carbide tool materials should focus on two aspects: First, refine the grains to achieve nano-scale crystallite grade. The smaller the grain size of the cemented carbide, the higher the hardness of the cemented carbide, the better the wear resistance, the higher the toughness and rigidity, thus expanding its application range. Second, the application of new technology and new technology to develop a new type of hard Alloys improve the intrinsic properties and quality of cemented carbides.

2. Development of coating technology
Tool coating technology plays a very important role in modern cutting and tool development. It has developed very rapidly since its inception, especially in recent years. Chemical coating (CVD) is still the main coating for indexable inserts. The layer process has successively developed new processes such as medium temperature CVD, thick film aluminum oxide, and transition layer. On the basis of the improvement of the base material, the wear resistance and toughness of the CVD coating are improved; and 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, and developed a heat-resistant coating suitable for high-speed cutting, dry cutting, and hard cutting. Through the innovation of the coating structure, a large number of new coatings such as nano- and multi-layer 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), which are several times harder than other tool materials. Diamond is the hardest substance in nature, and CBN is second only to diamond. In recent years, superhard tool materials have developed rapidly.

Diamond tool materials are divided into five categories: natural diamond (ND), synthetic polycrystalline diamond compact (PCD/CC), diamond film coated tool (CD), diamond thick film cutter (FCD) and synthetic polycrystalline diamond (PCD). . The crystal anisotropy of ND must be selected in the proper direction when using the knife grinding; the synthetic diamond is isotropic, its hardness is lower than ND, but the strength and toughness are better than ND.

Diamond tools can efficiently process non-ferrous and non-metallic materials. Such as copper, tungsten and other non-ferrous metals and their alloys, ceramics, hard alloys, various fiber and particle reinforced composite materials, plastics, rubber, graphite, glass and wood, but diamonds do not cut steel and other iron elements.

Cubic boron nitride (CBN) tool material is extremely hard and hard, and is an ideal tool material for high-speed finishing or semi-finishing hardened steel, chilled cast iron, superalloy, which can be obtained when CBN tools are used to process high hardness parts. Good surface roughness, so the use of CBN tools for cutting hardened steel can achieve "cutting and grinding".

4. Development of high speed steel materials
In the future development of tool materials, the development of high-speed steel materials is still mentioned. Although the sales of high-speed steel materials are decreasing year by year, the use of high-performance cobalt high-speed steel and powder metallurgy high-speed steel is still increasing. Two high-performance high-speed steels have better wear resistance, red hardness and reliability than ordinary high-speed steel. These high-performance high-speed steel tools have been widely adopted in the aviation field as people pursue improvements in cutting efficiency and change in their concepts. Such as aviation difficult-to-machine materials, drilling, expansion, hinge, and boring integrated high-precision composite tools used in automatic drilling and riveting machines, as well as various composite tools for processing complex profiles of aircraft parts.

With the advancement of science and technology, the development of advanced manufacturing systems, high-speed cutting, ultra-precision machining, and green manufacturing, and the realization of new requirements for tools, the future development of tool materials will also have significant development. The tool material and the workpiece material alternately develop and promote each other, which becomes the historical law of the continuous development of cutting tools. In the future, tool materials will face more severe challenges in terms of improved workpiece performance, increased processing throughput and improved manufacturing accuracy. Advances in materials science have driven the development of tool materials, and the development of tool materials should take into account the constraints of raw material resources. The emergence of new varieties, the changes in the proportion of new and old varieties, and the pattern of competition and complementarity between them will become new features in the development of tool materials in the future.

Development and trend of new technology, new structure and new varieties of cutting tools
With the rapid development of the manufacturing industry, key industries such as the aviation industry and the mold industry have repeatedly put forward higher requirements for cutting and processing, and promoted the emergence of new technology and new structure tools, and continuously enriched the variety of tools. Tool manufacturers at home and abroad, such as Xiamen Golden Heron Special Alloy Co., Ltd., in order to meet the requirements of aerospace manufacturing tools, work closely with aerospace manufacturers to develop new tools. Because aircraft parts have complex structure, high precision, thin parts and aircraft parts using titanium alloy, nickel-based alloy, carbon fiber and other difficult materials, it guides the development of aviation tools in the following directions.

(1) High precision, high efficiency and high surface quality.

(2) Ultra-high precision and long life.

(3) Difficult to machine materials such as high strength and high rigidity.

(4) Interlayer processing of various metal materials and various composite materials.

(5) Develop multi-function tools and high-efficiency special tools.

(6) The indexable tool is widely used. In the past, the majority of the tools in the aerospace materials processing, with the increase in the application of titanium alloys, high-temperature alloys and high-strength steels in aviation materials, the application of indexable tools has gradually increased, and the indexable tools have not been used. Welding, no cracks and other defects, to give full play to the cutting performance of the original blade, and reduce the machine tool stop grinding knife, the auxiliary time of loading and unloading tools, etc., the use of indexable tools can improve the cutting efficiency by more than 35%. At present, the indexable tools in Western countries have entered maturity, their varieties are increasing, the structure is optimized, the geometric parameters are more reasonable, and the occupancy rate in cutting tools is about 80%, which is less than 30% in China. Therefore, for the processing of parts in China's aviation industry, the wider use of indexable tools is the future development direction.

(7) Digitization of tool design and development. Modern tools should not only meet the requirements of advanced cutting technology such as high-speed cutting, dry cutting, hard cutting, and composite cutting, but also meet the higher requirements of product diversification, structural rationalization, and practical appearance. However, the design of tools in the past relied mainly on experience and relied on the test method. This design method has low efficiency, long design cycle and difficulty in developing new products. Obviously, it has hindered the development and use of new tools and cannot meet the needs of advanced cutting technology.

The development of modern cutting technology urgently requires advanced tool design technology. The tool design is characterized by difficult calculation of space angle, complex shape, large size and complicated cutting mechanism. However, with the rapid development of computer technology and CAD/CAM technology, advanced technology is adopted. The development of tools with technology and dedicated application software and tool simulation technology will be the direction of future tool design and development.

Development of new technologies related to tools
The cutting of the tool depends not only on the tool itself, but also on the use of the machine tool, the connection between the tool and the machine tool, the tool holder system, the tool balance, the tool safety monitoring system, etc., and the tool-related technology is also together with the tool technology. New progress has been made under the advancement of science and technology.

1. Tool holder system for high speed cutting
CNC machine tools such as machining centers have always used the traditional 7:24 solid taper shank tool system. Because of the combination of the taper and the taper, the joint rigidity of the shank and the main shaft is low. The spindle speed exceeds 10000r/min. The shortcoming is more obvious. For the tool change with ATC tool holder, the radial dimension of the tool may change after each tool change, and there is a problem of low repeatability. To solve these problems, the standard 7:24 tool holder is mainly improved. Inspired by the HSK tool holder, a new type of coupling technology with a 7:24 tool holder has emerged in recent years. For example, Japan Nikko Co., Ltd. and Dazhaohe have developed three types of contact (3LOCKSYSTEM) and double-sided (BIGPLUS) 7: 24 joint holders. Compared to standard 7:24 shanks, they have higher joint rigidity and precision for high speed, high efficiency cutting and are compatible with existing 7:24 shanks or machine tools, which is a 7:24 shank for the future. In the development direction, in addition to the modification of the standard 7:24 shank structure, the new HSK shank and KM shank are mainly used.

The HSK shank is a new type of high-speed tapered shank. The interface adopts the method of simultaneous positioning of the tapered surface and the end surface. The shank is medium-sized and the length of the cone is short, which is beneficial to realize the light-weight and high-speed of the tool change. Due to the use of end face positioning, the axial positioning error is completely eliminated, making high-speed and high-precision machining possible as well as the development direction of tool manufacturing in our domestic manufacturing plants. The connection technology between high-speed tools and spindles will continue to develop with the advancement of technology, and some new concept holders—HSK, KM, 3LOCK, BIGPLUS and other tool holders will be further improved and improved.

The current development direction of the spindle and tool connection technology is:

(1) adopting a double-sided positioning system;

(2) High clamping precision, good clamping rigidity and compact structure;

(3) the handle with balance and vibration damping device;

(4) Develop multifunctional and intelligent tool holders.

2. Tool dynamic balance technology
There are balance and safety issues for high-speed rotating tools. In high-speed spindle systems, the imbalance of any rotating body produces centrifugal force. The centrifugal force generated by unbalanced tools or shanks during high-speed cutting causes the machine to vibrate. The unbalanced amount will cause a large centrifugal force during high-speed cutting, and the irregular cutting force generated by the tool imbalance will cause irregular wear, and the result will affect the machining accuracy and surface quality of the workpiece on the other hand. Affect the service life of spindle bearings and tools, and more importantly affect the safety of high-speed cutting, so high-speed cutting requires careful balancing of the tool.

At present, foreign companies have developed special tool dynamic balance meters and vertical tool dynamic balance meters according to the requirements of tool dynamic balance, which can realize fully automatic tool dynamic balance measurement. The development direction of the new dynamic balance measuring instrument is accurate and efficient measurement, convenient operation and powerful function.

3. Development of cutting edge passivation
At present, most of the imported knives or indexable inserts of foreign countries have been passivated. The passivated tool or blade edge micro-defects are completely removed, effectively increasing the edge strength, and the tool durability can generally be increased by 20% to double. Most of the tools in China are not passivated, and the durability is Low, the tool consumption is large, so the passivation of the cutting edge of the tool is a direction of the current tool manufacturing development in China.

Conclusion
China's aviation manufacturing and processing is in a period of rapid development. The development of new aircraft and large aircraft poses a challenge to aviation manufacturing and processing. In the machining of aviation products, we must fully understand the importance of cutting tools in machining. According to the editor of HC Surface Treatment Network, in machining, the tool is called the "teeth" and "twin brother" of the machine tool. No matter what kind of metal cutting machine, you have to rely on this "teeth" to make a difference. If you leave this "twin brother", nothing can be done. In the future, with the improvement of the level of science and technology, the speed of equipment upgrading is getting faster and faster (10 to 15 years for another generation). To earn back equipment investment and create profits in a short period of time, it is necessary to study the potential of relying on tools to mine, so in machining It is necessary to configure a tool with excellent performance in order to make the machine run at high speed and high efficiency.

According to the editor of HC Surface Treatment Network, at present, the domestically produced tools can not fully meet the processing needs of the aviation manufacturing industry. They need to import a large number of tools every year. In the future, domestic tool manufacturing enterprises should accelerate their technological innovation and technological transformation. Increase research and development efforts, accelerate the development of new tools, multi-tools and tool materials, coating technology, improve product quality, enable domestic tools to reach the world's advanced level as soon as possible, and provide high-quality and efficient tool products for China's aviation industry.
 

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