Current situation and development trend of the hot

The current situation and development trend of high-speed and efficient machining technology

I. Introduction

at present, China has become an important subcontracting country of aircraft parts in the world. Boeing, McDonnell Douglas, Airbus and other world-famous aircraft manufacturing companies subcontract production of various parts from tail wing, fuselage, hatch to engine in China. Advanced processing equipment and processing technology must be used in the processing and production of these aircraft parts. For this reason, domestic aircraft manufacturing companies have carried out large-scale technological transformation and introduced a large number of foreign advanced processing equipment, making the CNC rate of aircraft manufacturing equipment in China higher and higher. At the same time, a large number of high-speed, efficient, flexible, composite, environmentally friendly foreign cutting and processing new technologies continue to emerge, making the cutting and processing technology have undergone fundamental changes. The application technology of cutting tools in aerospace machining field has entered a new stage characterized by the development of high-speed cutting, the development of new cutting processes and machining methods, and the provision of complete sets of technology. In sharp contrast, China's equipment manufacturing industry and the traditional tool industry with manufacturing as the main service object can not meet the requirements of aerospace industry for modern manufacturing equipment and advanced processing technology

next, combined with the current situation and development trend of machining technology in China's aerospace industry, the production and application of high-efficiency and high-speed cutting tools in China are emphatically introduced, and their own views on the development status and existing problems of China's tool industry are put forward

II. Current situation and development trend of processing technology in aerospace industry

1 Development trend and characteristics of aviation structural parts materials

① aluminum alloy structural parts represented by integral parts

in order to improve the reliability of parts, reduce costs and reduce weight, the traditional riveted structure is gradually replaced by the machined structural parts with integral thin wall. Since most of these parts are thin-walled and fine ribbed structural parts made of solid aluminum alloy, 70% - 95% of the materials need to be removed in processing, and high-speed cutting produces less heat, less cutting force and less part deformation, the only way to improve production efficiency is to use four axis or five axis linkage machine tools for high-speed milling

② hard cutting material parts represented by titanium based and nickel based alloy parts

due to the characteristics of titanium (nickel) alloy, such as high specific strength, good thermal strength and high chemical activity, titanium based and nickel based alloy materials are gradually used in important components of aircraft engines at present. After adopting high-speed cutting, the cutting speed can be increased to more than 100m/min, which is 10 times of the conventional cutting speed. The machining characteristics of this kind of material are: large cutting force, high cutting temperature, serious work hardening and tool sticking, and easy wear of tools

③ composite structural parts represented by carbon fiber composite parts

composite materials have become one of the main materials of the new generation aircraft body structure, such as large integrally formed wing wall panels on aircraft, integral lower wing with longitudinal walls, etc. The main cutting processes include drilling and trimming

2. Cutting technology of aviation structural parts

from the development trend and characteristics of aviation structural parts materials, it can be seen that the cutting technology of aviation structural parts mainly includes high-speed cutting technology for aluminum alloy structural parts and cutting technology for difficult to machine materials such as titanium (nickel) based alloys

① aluminum alloy high-speed cutting technology

at present, the spindle speed of machining centers suitable for aluminum alloy high-speed cutting is generally above 10000r/min, some can be as high as 60000 ~ 100000r/min, the cutting speed can be as high as 2000 ~ 5000m/min, the processing feed speed can be as high as 2 ~ 20m/min, the material removal rate is 30 ~ 40kg/h, and the acceleration (deceleration) speed of the workbench can reach 1 ~ 10g

in recent years, the backbone aircraft manufacturing enterprises of the two major aviation groups in China have carried out large-scale technological transformation, and the total number of CNC metal cutting machines introduced has exceeded 500, the vast majority of which are high-speed machining machines imported from Europe, the United States and Japan. However, due to the failure to keep up with the relevant supporting technologies of high-speed machining (such as cutting tool technology and high-speed machining process technology), The actual spindle speed of most equipment in production is about 10000r/min, which fails to give full play to the efficiency of the equipment. Some enterprises can only use domestic cutters below 6000r/min, and imported cutters above 15000r/min must be used

② machining technology of difficult to machine materials

the aviation power department uses nickel base alloys (such as Inconel718) and titanium alloys (such as tial6v4) to manufacture aircraft engine parts. For these difficult to machine materials, the domestic cutting technology level is still relatively low at present. Only a few enterprises have carried out some research and application, and the cutting speed can only reach 80 ~ 100m/min, which has not been applied in large-scale production

3. High speed cutting tool material

in the development of high speed cutting technology, tool technology plays a very key role. Great changes have taken place in high-speed cutting tool materials and tool manufacturing technology. Generally speaking, there are three kinds of tool materials suitable for high-speed cutting:

-- various coated cemented carbide tools

-- ceramic cutting tools

-- superhard material tool

4. High speed tool system

tools for high-speed cutting, especially high-speed rotating tools, have high requirements for their clamping technology, both in terms of ensuring machining accuracy and operating safety, due to their high rotation speed. 7: The traditional tool holder forms such as taper handle, spring collet, screw and the clamping method of the tool can no longer meet the needs of high-speed machining. Developing new high-speed tool system has become an important part of high-speed cutting system

in terms of tool holders: ISO standard HSK tool holders have become the mainstream of high-speed cutting tool holders

in terms of clamping parts: foreign tool companies have developed various tool clamping systems, such as hydraulic chucks, hot fitting chucks, and press in chucks

in terms of tool safety technology: according to the provisions of iso1940/1, the dynamic balance of rotating tools has reached above G40 level, and the unbalanced quality of some finishing high-speed milling cutters has reached G2, providing automotive manufacturers with high-performance materials and processing technology Level 5, and the tool dynamic balancing machine launched by American balance technology company can even be balanced to level g1.0

III. current situation and existing problems of high-speed cutting tools in China

1 Current situation of developing high-speed cutting tools in China's tool industry

in recent years, with the increasing demand for high-speed machining tools in China's aviation manufacturing industry, domestic tool manufacturing enterprises have increased their investment in technological transformation, carried out a series of research and development work for high-speed machining technology and high-speed machining tools, and achieved certain results

the following is a brief introduction to the development and production of high-speed cutting tools in several major domestic high-speed machining tool manufacturers:

① Zhuzhou Diamond Cutting Tools Co., Ltd.

the whole body cemented carbide milling cutter with ultra-fine PVD coating grades ybg102, ybg20 and CVD coating grades ybm351 developed by the company has been applied in aviation manufacturing enterprises with its rotational speed up to 30000r/min and feed speed up to 2m/min, The three edge solid carbide high-speed milling cutter developed by the company for the processing of thin-walled parts of aircraft cabin structure, with a rotational speed of up to 15000r/min, has replaced imports and formed localization. At present, 25000 ~ 30000r/min high-speed milling cutters are being developed

② Shaanxi aviation cemented carbide tool company

the company is an enterprise affiliated to the aerospace industry. At present, it is mainly for the aviation manufacturing industry to develop and produce welded spiral blades. The best way is to use a regulated power supply that can filter interference. End mills and integral carbide milling cutters are mainly supplied to aviation manufacturing enterprises. At present, the performance of domestic cemented carbide materials can not meet the requirements of high-speed machining of aviation enterprises. Therefore, the bars of integral cemented carbide milling cutters mainly rely on imports

③ Siping Xinggong cutting tools Co., Ltd.

in the early 1990s, the company was the first in the country to introduce the overall tool processing production line of German guhring company, specializing in the development and production of overall cemented carbide rod tools. The whole carbide cutting tools produced by the factory have been supplied to many aviation manufacturing enterprises. The bars of the company's overall carbide milling cutter are also mainly imported

④ Zigong Cemented Carbide Co., Ltd. Chengdu Branch

the cutters provided by the company for the aviation manufacturing industry are mainly solid cemented carbide rod cutters, mainly solid cemented carbide end mills. The single tooth high-speed solid cemented carbide end mills produced by the company can rotate at a speed of 8000 ~ 12000r/min, and the cutting speed of end mills for processing titanium alloy can reach 40m/min, The company also mainly relies on imports of bars of solid carbide milling cutters for high-speed cutting

⑤ Sentai inger (Chengdu) CNC Tool Co., Ltd.

the HSK hot fitting tool system for high-speed machining developed and produced by the company has reached the level of similar foreign products

⑥ Harbin Measuring and cutting tools Group Co., Ltd.

kelch links, a subsidiary of the company, mainly produces and sells high-efficiency and high-precision fixtures and tool hot set equipment. Among them, HSK tool handle can accept batch order

in addition, in recent years, Chengdu Tool Research Institute, Chengliang group company, Shanghai Tool Factory Co., Ltd. and other key enterprises in the tool industry have also increased their investment in technological transformation in cemented carbide materials, coatings and tool processing around high-speed machining technology, and achieved preliminary results. They have begun to provide products and technologies for the aerospace industry

2. At present, China's high-speed cutting tools development problems

at present, China's modern manufacturing industry needs high-precision, high-efficiency, high reliability cutting tools products and processing technology, more than 80% rely on imports, The reasons why China's cutting tool industry can't meet the needs of high-speed machining in the aviation industry are mainly in the following aspects:

① lack of understanding of the necessity and urgency of developing modern cutting tool industry

large and medium-sized state-owned enterprises in China's cutting tool enterprises produce standardized cutting tools under the condition of long-term planned economy, forming a habit of sticking to conventions. In recent years, although we have seen the rapid technological progress of foreign tool industry, we have not recognized that what modern manufacturing industry needs is "three high schools and one special school (high precision, high efficiency, high reliability and specialization)" modern tools. Although some advanced technologies and equipment have been introduced for more than a decade, the total amount of these equipment is not enough. Secondly, a large part of them have been used in the production line of standard cutting tools, and continue to produce the same standardized cutting tools. They lack understanding of the necessity and urgency of developing modern cutting tool industry

② insufficient understanding of the development characteristics of "high starting point, large investment, large-scale and internationalization" of modern tool industry, and the low input intensity also affects the development.

due to the insufficient understanding of the development characteristics of "high starting point, large investment, large-scale and internationalization" of modern tool industry by insiders, the input intensity is too low. There are many tool giants in the world whose assets exceed those of the main engine manufacturers. There are billions of dollars at most and hundreds of millions of dollars at least. From the perspective of the structure of the whole industry, China's tool industry should form a reasonable pattern of a few large and strong, and most small and specialized. However, from the overall perspective, the investment scale of a few leaders, 1-1.5 billion yuan, is the lowest threshold