Typical parts for machine tool machining in aircraft manufacturing

Structural features of aircraft parts

The typical structural features of aircraft parts are thin-walled structures with complex shapes, large changes in the shape of the bevel, and the appearance of hyperboloids, requiring precise forming. In order to reduce the weight of the aircraft, increase the maneuverability of the aircraft and increase the payload and range, lightweight design is adopted, and new lightweight materials are widely used.

In order to improve part strength and work reliability, the overall blank and the overall thin wall structure are mainly used. A large number of aluminum alloys, titanium alloys, high temperature resistant alloys, high strength steels, composite materials, and the like are now used. The thin-walled parts and honeycomb parts with complicated structure are not only complicated in shape, but also have many holes, holes, grooves, reinforcing ribs, etc., and the process rigidity is poor.

Typical parts that need to be machined in aircraft manufacturing

Typical parts that need to be machined in aircraft manufacturing, mainly aircraft fuselage structural parts and key parts of the engine:

1. Typical parts of the fuselage structure

Typical parts of the aircraft fuselage structure are beams, ribs, ribs, frames, siding, joints, slides and other parts. It is mainly composed of flat parts, elongated parts, multi-chamber parts and ultra-thin wall frame structure. The blanks are sheets, forgings and extruded aluminum alloy profiles. The material utilization rate is only about 5%-10%, and the amount of raw materials removed is large. At present, more than 90% of domestic aircraft parts are aluminum alloy parts, a small amount is stainless steel and titanium alloy steel, and more and more structural parts are used. The application of composite materials is the future development direction.

Structural features of typical parts of fuselage structural parts

(1) The outline size of the piece is getting larger and larger. If any beam parts have a length of 13m.

(2) The angle of the bevel angle of the part changes greatly, and the thin wall and the like. The thinnest part is only about 0.76mm, so the processing rigidity is poor.

(3) The structure of the parts is more and more complicated, and many parts adopt the overall structure.

(4) The dimensional accuracy and surface quality requirements of parts are getting higher and higher. For example, some defects such as burrs appear after machining are not allowed to be manually removed.

Main equipment required to process typical parts of aircraft fuselage

(1) Three-axis machining center, such as large gantry vertical machining center;

(2) Five-axis linkage machining centers, such as large gantry vertical machining centers, shall be equipped with A/B swing angle milling heads or A/C swing angle milling heads;

(3) From the perspective of development, a large gantry-type dual-spindle five-axis machining center is required, and the table size is 5m×20m for processing beam parts;

(4) Processing of aluminum alloy parts requires high-power high-speed machining center, power ≥40kW, spindle speed of 20000r/min or more, with two-axis swing angle milling head;

(5) Due to the large amount of cutting of the whole aluminum alloy parts, in order to facilitate chip removal, it is better to require a horizontal machining center where the table can be turned over 90°. At present, there is no such horizontal machining center in China;

(6) There are many types of aircraft fuselage structural parts, different shapes, and poor process rigidity, which requires a large number of fixtures. In order to reduce costs and shorten the production preparation cycle, various flexible fixtures are required;

(7) Sheet metal forming parts mainly involve the forming of skins such as skins, profiles and pipes, and require precise forming. In order to ensure the manufacturing precision, a large-size skin stretching machine, a skin roll forming machine, a three-axis rolling leveling machine, a profile bending machine, and a duct forming machine are required. Aircraft parts assembly also requires automatic drilling and riveting equipment;

(8) In order to reduce the weight of the aircraft, the application of composite materials is more and more, and the production of composite components requires a tape laying machine, etc. (the tape laying machine is still blank in China).

2. Key parts and processing requirements for aircraft engines

The key components of the aircraft engine are organic flaws, various types of blades and integral leaf discs.

Machine processing

There are three types of aircraft engine casings, one is a split ring structure, the other is a monolithic ring structure, and the other is a profiled casing. The casing material is a high-temperature resistant titanium alloy material that is difficult to process. The casing is also a thin-walled, weakly rigid structure with complex profiles, high precision requirements and high processing difficulty. The casing is a large-sized part, and a helicopter with a thrust of 15,000 kg has a diameter of φ800mm. The large-sized fan of the large aircraft has a size of φ1823.5mmx546mm, and the thinnest part has a wall thickness of 3mm. Therefore, the machining needs to be medium and large. Functional, high-precision CNC machine tools. For example, CNC vertical lathes and precision CNC vertical lathes with a diameter of φ2000mm; gantry-type five-axis linkage machining centers with a working table size of 2400mm×5000mm need to have dual-station, on-line measurement and simulation functions, and the tool magazine has a capacity of 60 knives. The CNC system has advanced programming functions, and the gantry type CNC boring and milling machine of 3000mm×5000mm is used.

Blade processing

The blade material of the aero-engine is a high-temperature resistant titanium alloy material, which requires a five-axis linkage machining center and a five-axis high-speed gantry milling machine to process the blade surface. The processing of the leaf root hoe requires the use of broaching and slow-feeding to the powerful grinding machine, and it is hoped that the powerful grinding machine has the function of changing the grinding wheel and the wheel dressing wheel. It also needs online measurement, program adjustment and automatic compensation.

Electrolytic processing of the blade surface can greatly improve the processing efficiency, and it needs to be polished by a numerical control six-axis belt polishing device. It is desirable to have a blade surface inspection device.

Large wide-chord hollow fan blades with wide chord, hollow and damped boss structure, diameter φ1600mm or more, fan tip speed up to 457m/s, lighter weight titanium alloy or resin-based material, five coordinates are required to manufacture such blades Blade milling machine; automatic polishing machine; combined sealing and diffusion bonding and superplastic forming equipment.

The blade has a lot of holes for cooling, and it is better to punch holes with electric pulses than to use laser drilling (laser drilling has a hardened layer), but now, the electromachining punching machine does not have a shallow hole display, and the operation is difficult. I hope to solve this problem and show the depth of the punch. Nickel-based single crystal turbine blades with high temperature resistance of 1100 °C have good high temperature strength and comprehensive performance. There are many cooling film holes with diameters of φ0.3~φ0.4mm on the blades. Single crystal melting furnace, ceramic core roasting furnace, core making machine, grinding center, numerical control jog grinding machine and electro-hydraulic beam flow equipment and small hole processing unit for blade hole making.

Whole leaf disc processing

The integral leaf disc is a thin-walled disc type with a bladed groove on the circumference of the leaf disc. Straight grooves can be processed by broaching and grinding. The circular groove can be machined by milling and forming, but the detection of the circular groove is difficult. The processing of the leaf ring and the leaf disc requires a CNC sleeper and a precision CNC vertical car. The processing machine tool is required to have good rigidity and high positioning accuracy, and the positioning accuracy is about 2 to 3 μm. The blade portion of the whole leaf disc can be processed by a five-axis high-speed machining center, and can also be processed by electric spark forming. The diameter of heavy-duty gas turbine blades can reach 2000-3000mm, which requires high-speed grinding machines with a grinding wheel speed of 100m/s or more.

The main equipment required to process critical parts of the engine are:

5-axis simultaneous machining center with A/B angle milling head or A/C angle milling head;

Five-axis blade milling machine;

Integrated leaf disc efficient machining center;

Workbench 3000mm×5000mm CNC gantry boring and milling machine;

Precision CNC vertical turning center;

CNC vertical lathe;

Precision CNC lathe;

Turning and milling composite machining center;

Special machining center for caries rounding;

Laser cladding machine tool;

Electric spark milling machine tool;

CNC horizontal lathe;

CNC vertical grinding machine;

CNC slow feed grinding machine;

End face grinding machine;

High speed rotor tip grinder;

700t electric screw press;

Plate-type parts without mold multi-point forming press;

Directional/single crystal melting furnace;

Electro-hydraulic beam flow equipment for blade making, small hole processing unit, vacuum heat treatment furnace, and the like.

The above equipment requires the machine to have sufficient rigidity, simple operation, clear human-machine interface, spline interpolation (NURBS) function, uniform process control to reduce the impact on the machining accuracy at the corner, and online measurement and simulation functions.