The thin-walled rotating body shell made by the spinning technology solves the technical problems such as low rigidity, high vibration and low precision in turning machining, or can not be processed at all. It has many advantages in the aerospace field.
The United States powerful spinning production φ3900mm large missile shell, radial size accuracy of 0.05mm, surface roughness Ra 1.6 ~ 3.2μm, wall thickness ≤ 0.03mm. US titanium manufacturing company with 1.5m vertical spinning machine spinning φ1524mm Ti-6Al-4V titanium alloy missile pressure vessel head, each head of the spinning time of 5min. Militia Intercontinental Missile the second stage solid engine shell uses Ti-6Al-4V titanium alloy, and with strong spinning forming, forming the titanium alloy shell weight by 30%. Around the aerospace model of light, high strength, large-scale aerospace demand, Germany MT Aerospace company using spinning technology to prepare φ1905mm high-strength Ti-15V-3Cr alloy propulsion system tank, and applied to the European Alpha communications satellite giant platform, significant weight loss of the satellite platform, increasing the payload.
China's spinning technology and equipment research from the early 1960s, titanium alloy spinning began in the last century 70's, after 40 years of development, the basic form from the equipment development to the development of a mature system.Titanium alloy and spinning products used in domestic spaceflight, such as rocket engine housings, vane hoods, gyro guide hoods, inner skin tiles, etc.The Ti8Al1Mo1V high titanium alloy for engine blade heat treatment to strengthen the titanium alloy spinning forming; TB2 titanium alloy for small spray Tube spinning and so on.
Xi'an Aerospace Power Machinery Factory developed the largest diameter of the titanium alloy cylindrical parts; through the positive and negative pass with two straight turn spirals φ500mm thin-walled semi-circular titanium ring, parts for spacecraft micro-dynamic attitude adjustment.
China Aerospace Science and Technology Corporation 703 institute of the use of universal rotation and strong spin-coupled technology to TC3, TC42 kinds of titanium alloy sheet for the blank, hot spinning prepared two kinds of titanium alloy hemispherical (φ 522mm × 2.0mm ), a cylindrical tank body (φ163mm × 2.0mm × 200mm cup, φ163mm × 2.0mm × 360mm and φ112mm × 6.0mm × 1000mm cylindrical).
In recent years, with the development of computer simulation technology, numerical simulation has been widely used in the analysis of metal parts spinning process. Institute of aerospace materials and technology, the computer simulation of TC4 cylindrical parts was carried out. The influence of the parameters such as the angle of rotation of the rotor, the trajectory of the wheel and the time of the rotation was analyzed of the TC4 titanium alloy cylindrical parts. Although the titanium alloy precision spinning technology for the field of space to provide a variety of alloy spinning rotary high diameter ratio of spinning parts, but the engineering application of parts and spinning complex analysis, need to be further strengthened. In general, the spinning technology in the domestic aerospace industry has been widely used, but the large diameter, thin-walled titanium alloy hot spinning process has no application examples, diameter 2.25m tank bottom of the overall spinning technology, diameter 5m low temperature storage box bottom melon molding, titanium alloy and high temperature alloy complex structure forming technology is still in the process of exploring the stage.
Rapid Prototyping Technology of Titanium Alloy Laser
Since the 1990s,with the rapid development of computer technology, laser direct manufacturing technology has become a hot topic in the field of manufacturing research. There are two methods in laser direct rapid prototyping that can be used to directly fabricate metal parts, namely, Selective Laser Melting (SLM) and Near King Forming (LENS). The research on laser direct rapid prototyping technology of large-scale titanium alloy structure mainly focuses on the United States. US AeroMet company in 2002 to 2005 to achieve a direct laser forming titanium alloy structure in the application of aircraft. 2001 Aero-Met company began for the Boeing company F / A-18E / F carrier-based joint fighter / attack aircraft small batch trial engine compartment thrust beam, wing rotary folding joints, spar, with reinforced wall panels such as titanium Alloy sub - bearing structure. 2002 developed a "Ti6Al4V titanium alloy laser rapid prototyping products," aerospace materials standards (ASM4999) and in the same year in the world to achieve the first laser rapid prototyping of titanium alloy sub-bearing structure in the F / A-18 and other fighters on the verification assessment and installed applications. In the aerospace sector, the NASA Marshall Space Flight Center (NASA) is selected for the manufacture of complex metal parts for aerospace engines in several models in 2012. Laser direct rapid prototyping technology is also often used for titanium alloy parts or mold repair.
China's titanium alloy structure of direct laser rapid prototyping technology research, since 2001 has been subject to the government's major scientific and technological management departments attach great importance to the aircraft, the engine and other titanium alloy structure of laser rapid prototyping manufacturing process, complete sets of equipment R & D and engineering applications Key technology research and other aspects have made great progress.
Beijing University of Aeronautics and Astronautics laser materials processing and manufacturing technology laboratory to aircraft sub-bearing titanium alloy complex structure as the object, to carry out laser rapid prototyping engineering application technology research, has made TA15 titanium alloy box nearly 200 pieces, completed the "laser Rapid forming TA15 titanium alloy structural parts in a plane on the installation of the review",the first piece of laser rapid forming TA15 titanium alloy structural parts through a certain type of aircraft on the application of the test assessment, so that China became the second in the world after the United States A master of the aircraft titanium alloy complex structure laser rapid prototyping engineering technology and the realization of laser rapid prototyping of titanium alloy structural parts in the aircraft on the application of the country.
Beijing University of Aeronautics and Astronautics Wang Huaming presided over the "aircraft titanium alloy large and complex overall component laser forming technology" project development and production of China's aircraft equipment so far the largest size, the most complex structure of titanium alloy and other high-performance difficult to process the key components of the whole metal, and in China large aircraft and other aircraft development and production in the practical application, so that China has become the world's only breakthrough aircraft titanium alloy large bearing capacity of the rapid prototyping technology and realize the application of the country.
Compared with the research and application of domestic aviation field, the application of laser rapid prototyping technology in China's aerospace field is basically still in the initial stage. In fact, the aerospace liquid and solid rocket engine difficult to process materials, complex sections of the structural parts and weapons difficult to process materials,light weight heat-resistant structural parts can be well selected laser melting technology to achieve high-precision machining.
The use of laser direct rapid prototyping technology to manufacture aerospace with the overall titanium alloy structure with high material utilization, processing margin is small, short cycle and high flexibility advantages. (Internal defects, grain and microstructure, etc.) and mechanical performance control is still a major bottleneck in the development and application of large-scale titanium alloy key structural components for laser rapid prototyping technology, but also in the process of laser rapid prototyping. The
In this paper, the advanced thermoforming technology of titanium alloy has also made some technical problems. At the same time, with the rapid development of the aerospace industry, the engineering application of large-scale titanium alloy components is relatively small. Precision thermoforming technology must enter a new period of development, in view of the outstanding advantages of titanium alloy and precision thermoforming technology, the combination of the two in the future contribution of aerospace industry will be more significant role in the future its main development direction is: (1) large-scale or large complex (thin-walled) structural parts of the overall precision forming, low cost, engineering applications;(2) computer simulation (simulation) technology, CAD / CAM technology, numerical control technology and the combination of precision forming technology,to provide a new way for the formation of new aerospace components.