Application of CNC High Speed ​​Machining in Aviation Product Manufacturing

Xi'an Aviation Power Control Co., Ltd. (West Control Company) is a professional manufacturer of engine fuel control system products of China Aviation Industry Corporation. It also cooperates with world famous aircraft manufacturing companies such as Honeywell, Hansheng, Goodrich, Eaton and other companies. Established a cooperative relationship and carried out the parts processing business of subcontract production. In the process of producing aero-engine products and aircraft parts, Xikong has undergone technological transformation due to the use of advanced processing equipment and technology, and introduced advanced processing equipment, so that the numerical control rate of the company's aviation manufacturing equipment is higher. The higher the efficiency, the high-efficiency, high-quality CNC machining is widely used in the company, which promotes the development of the company's production technology.
The application status of numerical control high-speed processing equipment in the product manufacturing of Xikong Company
In recent years, with the rapid development of the national economy and the national defense industry, the country's demand for aviation manufacturing equipment has also grown rapidly. In order to improve the manufacturing quality of aviation products and shorten the production cycle, AVIC West Control Company has increased investment in technological transformation, introduced advanced processing equipment, and equipped corresponding CNC tools. In the process of CNC high-speed machining, although related supporting technologies (such as tool technology and high-speed machining technology) have not been able to keep up with it in time, it is quite difficult to process some difficult-to-machine parts, but in the process of new product development and production. Also accumulated valuable experience. For example, the company adopts a curved cam machine machined by a high-speed five-axis linkage machining center. The surface of the cam part is a complex surface. The material is nitrided after heat treatment of 38CrMoAlA, and the surface hardness is HRC≥62. To complete the production and development, to ensure the processing accuracy of the part profile, the company's development technology experts, craftsmen from the cam profile design, the preparation of the processing program, the determination of the process route, the control of the heat treatment deformation of the parts, the selection of CNC tools, The design and manufacture of abrasive tools have been carried out in scientific research and technology, and finally the processing of complex curved surfaces with curved surfaces has been realized. The success of the development and processing of curved cams represents the high-tech, high-level and high-quality production capacity of Xikong. At present, the company continues to carry out new challenges and breakthroughs in the processing of special-shaped parts for aero-engine fuel control regulators.

1West Control Company's demand for CNC high-speed machining in the manufacture of aviation products
The company's aviation products are divided into military products and subcontracting 2, and the products are summarized as “high-precision”. First of all, in the structure of the company's aviation products, a large number of composite structural parts, as well as aluminum alloy, titanium alloy, stainless steel and high-temperature alloy materials. Secondly, in terms of process equipment, the metal-type aluminum alloy molds required for the development of high-performance aero-engine fuel control system components, the processing difficulty of colored, ferrous metal forging molds and forging steel molds are also increasing.

Traditional machining technology has been unable to effectively meet these needs, and the characteristics and advantages of high-speed machining technology provide a more effective solution for the processing of new structures, new materials and high-precision process equipment for aerospace products. High-speed machining with high spindle speed and high feed rate enables smooth machining and high precision. The surface quality of the machined workpiece can be almost comparable to the grinding process, achieving the effect of “milling and grinding”. Therefore, high-quality machining of shells, bushings, and profiled parts can be realized. For the slender, shaft and thin-walled parts with poor rigidity in aerospace products, it can be processed with high quality; for the processing of cavity surface on high-precision process equipment, the process of benching and trimming can be omitted and directly processed. Nitrided and quenched alloy steel curved cams and precision shutter bushing assemblies are also directly machined.

2 core technology of CNC high speed machining
CNC high-speed machining technology, CNC high-speed cutting tool technology, CNC high-speed machining technology and CNC high-speed machining testing technology are the core of developing CNC high-speed machining technology, and the choice of CNC cutting tools directly affects high-speed machining equipment to achieve high efficiency and low cost. Foundation. In the development of high-speed cutting, the development of machine tools and tools complements each other and promotes each other. In the cutting process system consisting of machine tools, tools and parts, the tool is the most active factor. The cutting performance of the tool depends on the material and tool structure of the tool, especially the productivity of high-speed machining, the service life of the tool, the processing cost, the machining accuracy and the quality of the machined surface. Reasonable choices depend on tool material and tool structure. Therefore, the choice of CNC tools is critical to the process of CNC high-speed machining.

In the following, combined with the current situation of the company's aviation products CNC high-speed machining technology and the problems that need to be solved, the paper introduces the situation and common problems of the CNC tools and high-speed machining tools in the high-efficiency and high-speed cutting of the West Control Company.

Development Status of CNC High Speed ​​Machining Technology for Aviation Products of Xikong Company
1 company's materials for aerospace composite structural parts
(1) Structural parts of monolithic stainless steel and aluminum alloy materials.

In order to improve the reliability of the parts, reduce the cost and reduce the weight, most of these parts are structural parts made of solid stainless steel and aluminum alloy. 80%~90% of the material should be removed during processing, and high speed. Cutting heat is less, cutting force is small, and parts are less deformed. Therefore, the only way to improve production efficiency is to use a machining center for high-speed milling.

(2) Titanium alloy and nickel-based alloy hard-to-cut material parts.

Titanium (nickel) alloy has the characteristics of high strength, good thermal strength and high chemical activity. At present, the company's important components of aerospace products using titanium-based and nickel-based alloy materials are gradually increasing. After high-speed cutting, the cutting speed can be increased to more than 80m/min, which is 8 times of the conventional cutting speed. The processing characteristics of such parts are large cutting force, high cutting temperature, severe work hardening and sticking, and easy wear of the tool.

2 cutting technology of aviation composite structural parts
From the development trend and characteristics of aerospace composite structural materials, the cutting technology of aerospace composite structural components mainly includes high-speed machining technology of aluminum alloy structural parts and cutting processing technology of difficult-to-machine materials such as titanium (nickel)-based alloys. .

(1) High-speed aluminum alloy cutting technology.

The spindle speed suitable for high-speed cutting of aluminum alloy is generally above 10000r / min, some can be as high as 60000~100000r /min, the cutting speed can reach 2000~5000m/min, and the processing feed rate is 2~20m / min. The removal rate of the material is 30-40 kg / h, and the addition (decrease) speed of the table reaches 1 to 10 g. At present, the actual spindle speed of most of the company's machine tool spindles in production is about 8000r / min, which fails to fully utilize the machine's performance. Some machine tools can only be used below 3000~4000r/min with domestic tools, and imported tools must be used above 8000r/min.

(2) Cutting technology for difficult-to-machine materials.

Inconel 718 (GH169) nickel-based alloy and Ti 6 6V4 titanium alloy are typical difficult-to-machine materials used in the company's products. Because they are difficult to process, they generally use very low cutting speeds. At present, the company is still exploring and researching the level of cutting technology. The cutting speed can only reach 80-100m / min, and it has not been applied in large-scale production. If high-speed machining is used, the production efficiency can be greatly improved, the tool wear can be reduced, and the surface quality of the product parts can be improved.

3 high speed cutting tool materials
Tool technology plays a very important role in the development of high-speed cutting technology. High-speed cutting tool materials and tool manufacturing techniques have undergone tremendous changes. Tool materials suitable for high-speed cutting are: PCBN cubic boron nitride tools, coated carbide tools, ceramic tools and superhard material tools.

4 high speed tool system
The tool holder is a key component of high-speed machining. Because of the high rotation speed of the tool, the tool for high-speed cutting has high clamping technology regardless of the machining accuracy and operational safety. Claim. The traditional tool holder and machine tool spindle are connected by 7:24 taper shank (BT, ISO). The traditional shank form and the tool clamping method of the spring chuck and screw can not meet the requirements of high speed machining. Therefore, the development of new high-speed tool systems has become an important part of improving high-speed cutting systems. In terms of the shank, Germany developed the HSK hollow short taper shank connection. The HSK short taper shank adopts a 1:10 taper. Its taper is shorter than the standard 7:24 taper shank, which can realize the flange end face and The simultaneous contact of the taper shank has high connection precision and rigidity. It can adopt the system technology of high-level balance and automatic balance of the spindle. It can guarantee the machining precision during high-speed machining, ensure high productivity, and is safe and reliable. At present, the I SO/DI S standard and the German DI N69893-1 HSK tool holder developed by the International Standardization Organizing Committee have become the mainstream of the company's high-speed cutting tool holder.

The status quo and problems of high speed cutting of CNC tools
1 The status quo of developing high-speed cutting tools in the domestic tool industry
In recent years, with the increasing demand for high-speed machining tools in the national aviation manufacturing industry, domestic tool manufacturers have carried out a series of research and development work on high-speed machining technology and high-speed machining tools, and have made certain progress. For example, the key enterprises in the tool industry, such as Chengdu Tool Research Institute, Chengliang Group Company, Shanghai Tool Factory Co., Ltd., have invested more in high-tech processing technology in the field of cemented carbide materials, coatings and tool processing. Initial results have been achieved, providing products and technology to aviation companies.

2Western Control Company's problems in high-speed cutting tools
At present, more than 80% of the high-precision, high-efficiency and high-reliability cutting tool products and processing technologies required by the company in the manufacturing industry rely on imports. China's tool industry cannot meet the needs of high-speed machining of aviation products. The main reason is that there is a big gap between the R&D and innovation capabilities of China's tool industry compared with foreign countries.

(1) The development of cemented carbide grades as the main tool material has a large gap with foreign products, which affects the improvement of the overall cutting level. At present, only the performances of individual brands such as Zhuzhou Diamond Cutting Tool Co., Ltd. and Chengdu Tool Research Institute are close to those of foreign products, and the speed of innovation and upgrade of new grades is slow, which makes China's large-scale cutting machining level of general machining industry. It is generally in a state of low speed and inefficiency.

(2) In terms of coating technology, in addition to the development of coating technology and equipment by Chengdu Tool Research Institute, China lacks basic theoretical research and lacks application technology and equipment development. The industry basically adopts equipment and introduces technology. Road.

(3) In terms of tool structure innovation, it is basically blank. At the international machine tool exhibition, it is difficult to find China's original tool products. The reason is that the main body of China's tool industry is still in the mode of producing traditional standard tools, and the output of general standard tools still accounts for the vast majority of major tool companies.

The backwardness of cutting technology and cutting tools in China is also reflected in the structure of China's tool industry. In China, only a few tool companies have two core technologies, namely hard alloy tool materials and coatings. Most tool factories lack cemented carbide materials. The core technology of some of the tool factories, although the introduction of coating equipment, but does not have the ability to develop, restricting the tool company to further enlarge and become stronger.

Common problems in the use of CNC high-speed processing equipment in the company
CNC high-speed cutting equipment realizes “zero-grinding” polishing of parts and precision machining of high-hardness materials, resulting in higher processing efficiency. While we are seeing that CNC high-speed cutting equipment is “stunning”, we must also clearly understand that there are some difficulties and problems in the application of CNC high-speed cutting equipment:

(1) The cost of CNC high-speed processing equipment is high and the investment return period is long. Not only the cost of the numerical control equipment itself is high, but also the cost of use is high. The price of the high-end high-speed machining numerical control equipment exceeds 150-1.6 million yuan. Under the high-speed running state, the average service life of the main shaft is generally only 3 years. The cost of a primary spindle is 1/3 of the total machine.

(2) The numerical control tools used in high-speed machining mainly rely on imports, and the procurement cost is high.

(3) The processing technology is required to be high, and the improper cutting amount will cause great damage to the tool. If the equipment is not used properly, the tool selection is not suitable. Not only can the performance of the equipment not be fully utilized, but the tools (including the blades) will be scrapped in large quantities, resulting in increased costs and huge waste.

(4) The numerical control high-speed processing equipment has high requirements for the staff who prepare the processing program. At present, the operator prepares the machining program by himself, and the skill level of the operator and the knowledge level of the material knowledge of the parts are uneven, which results in a large difference in the hardness and cutting parameters of the selected tool during machining.

(5) The processing preparation cycle is long.

(6) The maintenance and maintenance of machine tools are poor.

Effective application of CNC high speed machining equipment
If you think that you can purchase high-speed CNC machine tools, you can achieve efficient production. Actually, because many CNC high-speed machine tools can not be optimized, in addition to some technical reasons, the deviation of understanding and the improper use of methods are also The exertion of its effects has a negative impact. If all the product processing steps are completed on the CNC high-speed machining machine, the result is a waste of processing equipment. After many investigations and investigations, the author has a relatively successful practice at home and abroad. The CNC high-speed machining machine tools are used together with CNC machining centers, general machining machines and copy milling machines to give full play to their respective processing advantages to achieve the best processing system. The purpose of effective operation. For example, most of the cutting amount (heavy cutting) is performed by a common machining machine or a copy milling machine, and the remaining machining allowance of 2 to 3 mm is completed quickly, efficiently, and with high quality by the numerical control high-speed machining machine. This has many advantages: ordinary heavy-cutting machine tools are common, processing costs are very low; large processing capacity, high precision requirements are easy to achieve; tools are cheap; CNC high-speed machine tools are high-speed cutting, because the processing object is close to molding, cutting amount Relatively uniform; saves the polishing and polishing process and time, the finished parts can reach the surface finish of the mirror effect, the surface integrity is also very good; the matching size is accurate; although the tool is expensive at high speed, the processing time is short, cutting The amount is small and cost-effective. Therefore, the company combines product characteristics, appropriate supporting equipment, and exerts high-precision, high-efficiency, high-quality processing characteristics of CNC high-speed processing equipment to achieve high-efficiency, high-precision, low-cost manufacturing of products.

Now the country vigorously advocates the combination of production, education and research, strengthens scientific research and development and the transformation of results. The aviation industry is undergoing profound changes and an important period of transformation. As a AVIC industrial enterprise, Xikong Company can fully improve the application level of CNC high-speed machining technology. Give play to its advantages and effects? Indeed, compared with the developed countries of CNC machine tools, there is still a certain gap between the domestic CNC high-speed processing equipment and technical level, and the application level of CNC high-speed machining technology of the company's aviation products is improved. The company's scientific and technological experts, technicians, equipment and tool management personnel are duty-bound. It is necessary to closely integrate with the production unit to carry out research on numerical control high-speed machining equipment, basic process test research, cutting tool research, integrated system process integration research and related technical training.

Give full play to the role of CNC high-speed cutting
Expand the range of high-speed cutting parts and high-speed cutting technology, and establish a database of cutting processes for aerospace products. Develop high-speed machining programming technology, promote high-speed cutting technology, dry (quasi-dry) cutting green manufacturing technology, and actively establish a sound promotion and application mechanism.

For the aerospace products commonly used materials, such as aluminum alloy, titanium alloy, stainless steel, nickel-based superalloy and other materials to carry out cutting process test research, establish a high-speed cutting database of related materials, carry out high-speed cutting processing state monitoring, collect information, and continuously improve.

Strengthen the research on the high-speed processing and manufacturing process specifications of the company's aviation products. According to the requirements of the quality management system GJB9001A, the provisions of the new product development process documentation and the standard development process plan, under the premise of ensuring the qualified assembly of aviation products, in the assembly test development process, repeated trials and trials. From the perspective of equipment, it is necessary to use CNC high-speed processing equipment as the core, high-middle and low-grade processing equipment to match, comprehensively select equipment characteristics, and prepare new research drawings and processing process roadmaps to reduce costs, improve efficiency, and develop and produce good quality. Development process documentation system with high precision and stable assembly performance of product parts.

Carry out technical support and personnel training in CNC high-speed machining, and cultivate high-quality technical talents for the effective application of CNC high-speed machining technology in the company's aviation products.

Conclusion
CNC high-speed cutting tools and related technologies are the basic conditions for achieving high-speed CNC machining. CNC high-speed cutting technology is an advanced manufacturing technology. The application of CNC high-speed cutting technology can not only greatly improve the efficiency, quality and cost of machining, but also Drive the development of a series of high-tech industries. Strengthen the basic research of CNC high-speed cutting on CNC tool materials and tool structure, establish a complete process parameter table and numerical control high-speed cutting database, CNC high-speed cutting safety technical standards, research on CNC high-speed tool online monitoring system, CNC high-speed tool dynamic balance, etc. In combination with the actual situation of aviation material processing, based on the existing tool design and manufacturing capabilities, and drawing on advanced experience at home and abroad to accelerate the research and development of CNC high-speed cutting tool system and CNC high-speed cutting machine tool system, to further improve the company's aviation industry CNC machining technology. Level.

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