News

Exploration and Application of Production and Processing of Aviation Titanium Alloy Fasteners

In the 21st century, aerospace has shown broader development prospects, with high-level or ultra high level aerospace activities becoming more frequent. Their role will far exceed the field of science and technology itself, and will have a broader and more profound impact on politics, economy, military, and even human social life.
It should be pointed out that the tremendous achievements in the aerospace industry are inseparable from the development and breakthroughs of aerospace material technology, and titanium alloys have an irreplaceable position in the aerospace field due to their high strength and light surface quality.
Titanium alloy fasteners generally require solution aging heat treatment to ensure that they meet the shear strength requirements of 660MPa and tensile strength requirements of 1100MPa,
Fasteners made of titanium alloy require a detailed inspection, in addition to observing the appearance for any damage, as well as mechanical and metallurgical properties. Titanium alloy fasteners have strict material standards, quality, performance standards, and requirements,
The processing technology conditions for titanium alloy fasteners should comply with the relevant requirements proposed in the AMS4967 standard (wire, annealing, forgings and rings, heat treatable titanium alloy rods), which has clear standard and performance requirements in material tolerances, dimensions, metallography, appearance, defect control, and mechanical properties.
1. Problems in the processing of titanium alloy fasteners
Corrosion issue. When installing titanium alloy fasteners, it is easy to form a certain gap, which can cause surface coating to flow in between metal air strikes, making the fasteners vulnerable to clothing during the production process. During subsequent use, the tightness of the connection will be affected. The main reason for the corrosion resistance of titanium alloy materials is the protective oxide film on their surface. This film can effectively protect the titanium alloy inside the material from oxidation, thereby improving the corrosion resistance of the titanium alloy material.
Problems in turning machining. Titanium alloy material is a difficult to machine material with poor thermal conductivity. The heat generated during the machining process does not diffuse through the parts and machine structure, but is concentrated in the cutting area, which has a strong sensitivity to notches and may lead to edge breakage and deformation; If the blade becomes dull, it will generate even higher heat and further reduce the tool life. The high temperature generated during the cutting process will also cause the workpiece to continuously harden. This phenomenon will affect the surface integrity of titanium and may lead to inaccurate geometric accuracy of the part, seriously reducing its fatigue strength. Generally speaking, under reasonable mechanical processing conditions, the turning process is not difficult. If it is for large-scale production, continuous cutting, or cutting with relatively large metal removal, hard alloy cutting tools need to be used; Reasonable adjustment of steel cutting tools is required during forming cutting or cutting, and metal ceramic cutting tools may be used if necessary.
The precision issue of machining titanium alloy fasteners. The precision requirements for machinery will be higher. In mechanical production, due to the fact that the cutting tools are in a state of working wear during each production process, and are calibrated according to the program, titanium alloy fasteners have a higher density. The cutting tools are easily worn during the machining process. Even in a worn state, the cutting tools are still machined according to the program, which can easily affect the precision of the fasteners during the machining process. If the precision of fasteners is not strictly controlled within the error range throughout the entire machining process, titanium alloy and other materials cannot be tightly connected during use, which will have a certain impact on subsequent use. Improving the precision of titanium alloy fasteners in mechanical processing production is a major challenge that needs to be overcome in the production process. For example, the fastener process product shown in the picture is made in a high-precision production workshop, which has better connection performance.
2. Process Tips for Processing Titanium Alloy Fasteners
Using blades with regular angular geometry to reduce cutting force, cutting heat, and workpiece deformation; Keeping the blade edge sharp, blunt cutting tools are the cause of thermal accumulation and wear, which can easily lead to tool failure.
Maintain a constant feed to avoid hardening of the workpiece. During the cutting process, the tool should always be in the feed state, and the radial cutting amount ae during milling should be 30% of the radius.
High pressure and high flow cutting fluid is used to ensure the thermal stability of the machining process and prevent surface deformation of the workpiece and tool damage caused by high temperature.
Process titanium alloy in a soft state as much as possible, as the material becomes more difficult to process after quenching, and heat treatment improves the strength of the material.
Use a large tool tip arc radius or chamfer to cut in and insert as many cutting edges as possible into the cutting process. This can reduce the cutting force and heat at every point, preventing local damage. When milling titanium alloys, the influence of cutting speed on tool life (vc) among various cutting parameters is *, followed by radial cutting amount (milling depth) (ae).
3. Applications in aviation
According to data, titanium alloy fasteners are widely used on airplanes.
Each domestically produced C919 aircraft in China requires approximately 200000 pieces of titanium alloy fasteners, and to complete the first batch of 100 start-up orders, 20 million pieces of titanium alloy fasteners are needed.
If calculated based on the plan to produce 150 large aircraft annually in 2018, 30 million pieces of titanium alloy fasteners are needed each year. The development potential of titanium alloy fasteners is enormous, and the market prospects are very promising.
In recent years, the rapid development of China's aerospace industry has led to a sharp increase in demand for aviation fasteners.
In addition, China has made great progress in the manufacturing of large aircraft. Although there is still some time before the first flight in 2014, 100 start-up orders were obtained at the air show at the end of 2010. To fulfill these orders, there is a huge demand for titanium alloy fasteners, and the market prospects for titanium alloy fasteners are very promising.
To ensure the continuous and safe flight of aerospace equipment, extremely high requirements are placed on titanium fasteners. Especially after commercial aircraft are put into operation, they need to operate for 20-30 years and fly continuously for more than ten hours a day. The requirements for fasteners are even higher than aerospace standards, and titanium alloy fasteners can meet the above needs.
In addition, titanium alloy fasteners can greatly reduce the weight of the aircraft itself, not only improving aircraft performance, but also reducing operating costs, mainly reducing fuel consumption.
Such excellent performance is bound to be widely used in aircraft manufacturing, and the main problem currently hindering its development is titanium alloy materials.
Analysis of the mechanical industry indicates that China is a major producer of fasteners, with output ranking first in the world for many consecutive years. However, China is not a strong producer of fasteners.
Most of the fasteners produced in China are low-end and low value added products. The market share of high-end fasteners such as aviation fasteners is relatively low, and the product types and specifications are very limited. The related technology and production still need to be improved.
*In recent years, titanium alloy materials have been widely used, which cannot be separated from innovation driven and national grand plans.
With the continuous decrease in processing costs of titanium alloys, their application in aircraft structures will become increasingly widespread in the future.
With the rapid development of China's aviation industry and the continuous improvement of aircraft performance requirements, future high-performance aviation fasteners require higher strength, higher fracture toughness, and higher fatigue performance in the manufacturing of titanium alloy materials.

[ 上一页 ] What are the class...[ 下一页 ] Application of Num...