Efficient machining of typical components in the aerospace industry

Abstract: In recent years, the continuous development of workpiece materials, tool materials and structures has promoted the development of aerospace manufacturing. It can be said that the continuous development of cutting tools is the driving force for the continuous development of aerospace manufacturing. How to choose the correct processing plan and use the tool for high quality cutting has become a very important industry topic. This article provides some efficient machining solutions for the processing difficulties of some typical components.

At present, the aerospace industry is developing rapidly, and the material performance requirements are getting higher and higher, which makes the application of difficult-to-machine materials such as titanium alloys, superalloys and composite materials more and more widely. For example, titanium alloys are mainly used in integral blade discs and engines. Frames, fan casings, impellers and landing gears; superalloys are mainly used in shafts, disk shafts, turbine disks, combustion casings, ISO S holes, etc. Composite materials are mainly used in central wing boxes, vertical tails and machines. Wing and other aspects.

These are typical difficult-to-machined structural parts and have the following typical features: 1 The internal structure is complex, such as deep internal cavity, the tool is shaped, overhanging, easy to cause vibration during processing, difficult to remove chips, and need to be fully prepared during the machining process. Consider the safety clearance between the tool and the workpiece, as well as the dovetail root groove and other poorly accessible grooves. 2 Thin-wall structure, the impact of cutting force on the degree of deformation of the workpiece should be fully considered when selecting the tool. 3 dimensional accuracy requirements are high.

The aerospace various components have complex structures and high processing precision, which is difficult to process. In addition, the materials are mostly difficult-to-machine materials such as high-temperature alloys and titanium alloys, which makes the processing difficult. The materials have the following Features: 1 chemically active, high-hardening layer will form at high temperature; affinity is also large, easy to adhere to the friction surface. 2The thermal conductivity is poor, and the heat dissipation during the cutting process is poor, which causes the temperature of the cutting edge of the tool to rise sharply, the tool wear is accelerated, and the life is shortened. 3The modulus of elasticity is small, and under the action of cutting force, deformation is easy to occur, and the surface of the machined surface rebounds, causing severe friction between the flank face of the tool and the machined surface.

The complexity of aerospace components, the rigor of processing requirements, and the difficulty of processing materials have raised higher product and service requirements for tool companies. After years of development, some tool companies at home and abroad have provided many efficient processing solutions for the industry.

1. Processing of the disc shaft

The disc shaft structure is shown in Figure 1. There are two challenging features in the machining of the spool: deep bore and dovetail.

The following solutions from Sandvik Coromant Cutting Tools Co., Ltd. can safely and reliably complete this challenging feature processing:

(1) Anti-vibration blade with a Sandvik Coromant Capto® interface . Slender tools are used when machining to a depth of 150 mm, but the tool is prone to vibration and the chips generated during machining need to be removed from the grooves. Anti-vibration blades with a Sandvik Coromant Capto® interface (see Figure 2) can effectively solve vibration problems.

The use of the anti-vibration blade for processing has the following significant advantages: 1 The elliptical cross-section of the toothed interface provides good stability and accessibility. The 100 mm high blade provides optimum cutting fluid supply and aids in chip removal. 2 For the longer blade (4 times width), the patented anti-vibration device will be used in design, and the amount of back-feeding knife can be four times higher than that without the anti-vibration device. 3 Cycloid turning technology combined with the ceramic blade of material CC6060 reduces the number of passes. 4 to achieve reliable process safety, and the production efficiency is more than doubled.

The root groove is machined using an elbow blade. Elbow blades are particularly suitable for aero-engine parts turning. Complementing the standard CoroCut 90° blade product line, Sandvik Coromant has introduced 90°, 45° and T-shaped semi-finished products to meet more specific needs (Figure 3).

(2) Using RCMX turning inserts suitable for finishing, as shown in Figure 4, the blades have the following characteristics: 1 RCMX carbide inserts can be mounted on the insert pockets of the corresponding ceramic inserts, which reduces the tool's The quantity reduces the installation time. The groove shape of 2RCMX produces less cutting force and excellent cutting performance.

2. Turbine disk processing

The materials of such parts (such as Inconel 718, Waspalloy, and Udimet 720) are generally more difficult to machine, and the difficult-to-machine features are usually contoured by the cavity, and various interference problems are avoided. Zhuzhou Diamond gives the following specific solutions:

(1) The shank realizes the processing of complex cavities (see Figure 5).

(2) The shaped cutter bar realizes the processing of the dovetail groove (see Figure 6).

3.ISO S hole processing

Surface integrity is critical when processing critical aero engine parts. ISO S hole machining is one of the final processes, which makes reliability and safety very important for delivering high quality parts. The following hole machining solutions from Sandvik Coromant are well suited to ISO S hole machining requirements.

(1) Drilling requires harsh holes. The size and location of the holes have a major impact on the second process, and the unique micro-groove shape of the CoroDrill® R846 (see Figure 7) meets this requirement.

(2) High quality reaming. High tolerance requirements, hole straightness and hole quality are essential elements when reshaping complex and delicate aerospace parts. The CoroReamer® 835 (see Figure 8) has a dedicated groove shape, a distinctive cutting edge design and optimum cutting fluid distribution to ensure top-quality hole machining, combined with the CoroChuck® 930 holder for best results .

(3) Safety tapping. The CoroTap® 200 SD (see Figure 9) is optimized for the through hole procedure of ISO S materials. The new tapping tool provides smooth cutting and reduces the risk of chipping and improved surface quality.

(4) High accessibility boring. The small diameter holes of honing ISO S materials require extremely high process safety. The new CoroBore® 824 XS (see Figure 10) is capable of boring small holes under large overhangs with small tolerances and excellent surface finish quality due to the ability to make micrometer diameter adjustments.

4. Landing gear processing

Take the aircraft landing gear (see Figure 11) as an example to illustrate the effectiveness of the improved machining tool for improved machining efficiency and reduced machining costs. The material of the landing gear is titanium alloy, which is very difficult to process. It takes about one month for a traditional tool to process a part, and because the parts are difficult to process, the tool wears very quickly, and the cutting edge of the tool can only be processed for less than 1 hour. As a result, the tool for processing such parts is very expensive and the tool cost is high. Under such circumstances, it is eager to find a tool that can greatly improve the processing efficiency while reducing the processing cost or not increasing the processing cost.

For the practical needs of machining, Iskar proposed a large feed milling cutter solution. The FTP milling cutter is a new type of tool developed by Isca based on the HTP gear shaping cutter. It can meet the requirements of both milling and large feed milling, and the cutting is light. For the processing of aerospace difficult-to-machine materials, Iskar has developed an ER-groove and IC830 carbide-coated grade that is more suitable for processing difficult-to-machine materials such as titanium alloys.

The FTP large feed milling cutter with a diameter of 63 mm has 6 effective teeth and 4 cutting edges per blade. The tool can realize face milling and slope milling, and can achieve fast tooling with a milling allowance of no more than 1.8 mm. The maximum distance per tooth can reach 1.5~2.0 mm. The tool types used are: tool body FTP D063-6-27-R-LN10; blade FTP LNHT 1006 ER IC830, as shown in Figure 12.

The FTP milling cutter has the following advantages:

(1) The positioning method is reliable. The front and back sides of the blade are provided with cutting edges, and the blade is thickened. The positioning surface is divided into several small planes, which are located on the side of the blade and form a dovetail groove structure with the rake face, which makes the blade more secure when it is loaded into the blade body, and the tool is added. Rigid, can withstand greater cutting forces, achieve greater feed, while reducing the impact of cutting vibration on tool life.

(2) The blade is economical. Compared to the traditional APKT insert with 2 cutting edges, the FTP milling insert has 4 large feed cutting edges per insert, which is more economical. The special design of the insert and the cutting edge groove shape greatly improves the blade positioning strength and the blade. Self-strength; the cutting process is more stable, the cutting force is smaller, the cutting heat generated by the tool in the actual cutting process is less, the service life of the cutting edge of the tool is greatly improved, and the service life per cutting edge can be increased by about 3 times, effectively reducing The cost of the tool.

5. Vertical tail processing

The vertical tail structure is shown in Figure 13. The main challenges in machining this type of structural part are hole machining, trimming, and so on.

(1) The hole processing of CFRP is shown in Fig. 14.

Working conditions and application requirements: 1 high fiber content carbon fiber reinforced composite material - unidirectional tape material. 2 fiber fragmentation is the least. 3 high surface quality and dimensional accuracy. 4 CNC machining center.

Machining solution: 1 CoroDrill® 854 drill tip, 6.35 mm diameter. 2N20C diamond coating.

Cutting parameters: 1vc = 150 m / min. 2fn=0.06 mm/r.

Features: 1 hole quality is good, no fiber fragmentation. 2 Tool life is 800 holes.

(2) The trimming process of carbon fiber is shown in Fig. 15.

Working conditions and application requirements: 1 carbon fiber skin. 2 fiber fragmentation is the least. 3 high surface quality: Ra = 1.25 μm.

Machining solution: 1 CoroMill® Plura custom machining solution. 2 Option 1: Diamond coated carbide tool. 3 Option 2: PCD welding tool. 4 Tool diameter is 10 mm with 2 cutting edges.

Cutting parameters: 1 speed n=10 000 r/min, table feed vf=3 200 mm/min. 2 roughing: fz=0.03~0.08 mm/z. 3 finishing: fz = 0.02 ~ 0.04 mm / z.

The design and use of future tools should consider the matching of the tool material and the workpiece material. The tool material should be adapted to the needs of the processing object, especially to meet the processing needs of difficult materials, and determine the reasonable tool materials for different workpiece materials and processing conditions. structure type. High-speed, high-efficiency and high-precision machining requires a variety of excellent tools. High toughness and high strength matrix + high hardness and high wear resistance are the main development directions of future tools.

Galvanized Gabion

Gabion boxes are made of Galvanized Wire / ZnAl (Golfan) coated wire / PVC coated wires, the mesh shape is hexagonal style. The gabion boxes are used widely in slope protection, foundation pit suporting, mountain rock holding, river and dams scour protection.