Through a survey of the main key parts manufacturing processes and equipment of aircraft and aero-engines, it is found that the aviation industry urgently needs special equipment to process composite parts, and the engine and parts processing requires a large number of high-precision machine tools.
“High-end CNC machine tools and basic manufacturing equipment†is one of the 16 major scientific and technological projects identified in the “National Medium- and Long-Term Science and Technology Development Plan (2006-2020)â€. At present, the special implementation plan has entered the stage of expert demonstration and approval. In June and July of this year, the Industry Development and Reform Commission Industry Department commissioned the China Machine Tool Industry Association to organize an industry survey to further demonstrate the objectives, implementation conditions and work plans of major projects. Accordingly, the association organized 30 industry experts to conduct special research on 61 companies and institutions in the aviation, shipbuilding, automotive, power generation equipment and machine tool industries.
According to a person from the China Machine Tool Industry Association, the focus of this survey is to investigate the manufacturing process and equipment of major key components of aircraft and aerospace engines. The main users of the aviation industry research are: Shenyang Aircraft Company, Shenyang Liming Aero Engine Company, Shanghai Aircraft Manufacturing Plant, Xi'an Aircraft International Corporation, and Xi'an Aero Engine Company.
Urgent need for special equipment to process composite parts
Typical parts of the aircraft include beams, ribs, ribs, frames, siding, joints, etc. The blanks are plates, forgings and extruded profiles. At present, more than 90% of the parts are made of aluminum alloy, and a small amount is stainless steel and titanium alloy.
The main structural forms of aircraft parts fall into two categories. One type is long-plate type parts, such as beams, rims, ribs and siding parts. The aspect ratio is large, and the inner and outer edges are spatial curved surfaces with complex shapes. For example, a certain type of aircraft edge strip part is a T-shaped thin-walled part, the material is a T-shaped high-strength aluminum alloy extruded profile, 6700mm×110mm×200mm, with an angle requirement of 91.68°, the theoretical shape accuracy is plus or minus 0.25mm; the upper wall Both the plate and the lower plate are made of high-strength aluminum alloy, the longest is 5600mm, the widest is 750mm, the thinnest is 2mm, and it needs to be clamped by vacuum platform during processing. The processing of aluminum alloy parts requires high-speed cutting because the beam and wing The whole wall is made of the whole material.
The other type is frame-shaped parts, such as profiled ribs, brackets or joints. Mainly frame-shaped structure, complex shape and large processing capacity. For example, the rear beam hinge joint of a certain aircraft is the main force-receiving part of the balance tail. The structure is complex, the blank is forging, the outer dimension is 420mm×340mm×225mm, the geometrical tolerance is 0.1mm; the rib web blank is high-strength aluminum alloy board. The largest 925mm × 260m × 76mm, the smallest 590mm × 190mm × 35mm search enterprise network, divided into single-sided frame, double-sided frame two kinds of web, the thinnest part is only 0.9mm, material utilization rate is 12%, which means 88% The material was cut off. The warehouse door is also a frame type component. The material is 7150~T7351 high-strength aluminum alloy. The blank size is 40mm×3100mm×800mm. There are also single and double-sided frames, as well as door ribs and door frame joints.
In order to improve the processing efficiency, the aluminum alloy parts are processed by high-speed cutting, which requires the use of high-speed machine tools. The spindle speed is above 15000r/min-18000r/min, the acceleration is about 1g, the positioning accuracy is 0.02mm, the machining accuracy is 0.1mm~0.15mm, and the whole stroke accuracy is achieved. 0.3mm.
In the aerospace industry, the use of titanium alloys is increasing, and aluminum-lithium alloys are also beginning to be applied. Machining titanium alloy parts requires sufficient torque and power for the machine tool. It belongs to high-torque and powerful cutting. The spindle speed is about 6000r/min. The machine tool should have sufficient rigidity and five-axis machining function. It should be equipped with A/B swing angle milling head or A / C swing angle milling head. The rigidity of the A/B swing angle milling head is good. The rigidity of the A/C swing angle milling head is less. The five-axis linkage has a swing angle of plus or minus 25° and the machine positioning accuracy is 0.02 mm.
The use of composite materials in the aircraft industry has increased, especially for carbon fiber materials. At present, there is an urgent need for special equipment for composite processing, such as tape laying machines. The key to the tape laying machine is to have functions such as inspection, laser positioning, infrared monitoring, compaction, and ultrasonic cutting.
High-precision machine tools for engine machining
The key components of the aero engine are mainly the casing and the blades. There are three types of casing: split ring structure, integral ring shape, and shaped shell. The aero engine casing is a high-strength high-strength titanium alloy material. The front casing temperature is 200°C-300°C, while the rear casing is resistant to higher temperatures, which is difficult to process. The casing is also a large part. A 15,000 kg thrust engine has a diameter of 800 mm and a long processing time. Therefore, it is important to improve the machining efficiency.
Machine processing requires multi-functional, high-precision CNC machine tools, such as CNC vertical lathes, CNC precision boring machines and five-axis machining centers. It requires dual-station, on-line measurement and simulation functions. The magazine has a capacity of 60 knives and the CNC system has advanced Programming function, high-speed machining spindle speed 10000r/min or more, spindle power 15 kW ~ 30 kW. Roughing is done by heavy cutting Hanyang Technology, so the machine tool must have sufficient strength. Finishing uses high-speed cutting, and many small holes in the casing are punched with an electric machine.
Blade machining is divided into two parts, namely the turbine blade and the impeller (ie the integral blade disc). The blade material is a high-temperature resistant titanium alloy material, which requires a five-axis linkage machining center, a five-axis high-speed gantry milling machine, and the like, and the milling process is large. The broaching machine for the processing of the roots and the slow-feeding to the powerful grinding machine requires the slow-feeding grinding machine to have the function of changing the grinding wheel and the wheel dressing wheel. It also needs online measurement, program adjustment and automatic compensation.
Electrolytic machining of the blade surface can greatly improve the processing efficiency, and it needs to be polished by numerically controlled six-axis belt polishing equipment, which requires the machine to have a blade surface inspection device. If electrolytic machining is used, it is necessary to prevent corrosion, electrolyte treatment, and insulation measures, which will increase environmental protection costs.
The blade has a lot of holes for cooling, and is punched with electric pulses, such as laser drilling (laser drilling has a hardened layer), but now the electroforming hole has no hole-pervious display, and the operation is difficult. The user unit hopes to solve this problem and enable the machine to display the punching process.
Most need a five-axis linkage machine
The structural features of typical parts of the aerospace industry are the extensive use of integral thin-walled structures with complex shapes. In order to increase the mobility of the aircraft, increase the payload and range, reduce the cost, carry out lightweight design and extensive use of new lightweight materials, and the material performance requirements are getting higher and higher. A large number of aluminum alloys, high-temperature alloys, titanium alloys, high-strength steels, composite materials, engineering ceramics, etc. are now used. The thin-walled parts and honeycomb parts with complicated structure have poor process rigidity.
The aviation industry needs a five-axis linkage machining center with A/B swing angle or A/C swing angle, high-speed machining center, large double-gantry vertical machining center, large-scale CNC gantry boring and milling machine, precision CNC lathe, large CNC precision vertical turning Center, turning and milling composite machining center, blade efficient machining center, section arc tooth grinding machine, high speed rotor tip grinding machine, slow feeding strong grinding machine, broaching machine, electric processing machine tool, laser cladding machine tool, and moldless parts Point forming presses, directional single crystal melting furnaces, electro-hydraulic beam devices, and the like. The machine tool is required to have sufficient rigidity, simple operation, clear human-machine interface, spline interpolation (NURBS), process uniform control and online measurement simulation.
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