Aerospace Application Titanium:Research on laser deposition additive manufacturing technology for large key bearing products of launch vehicle

Additive Manufacturing (AM), also known as 3D printing technology, is a high-end digital manufacturing technology that has developed rapidly in recent years. Additive manufacturing based on three-dimensional CAD design data, the use of discrete materials layer by layer to manufacture solid parts, is a "top-down" material accumulation manufacturing process, and traditional material reduction manufacturing (such as machining, chemical milling and other material removal methods) and equal material manufacturing (casting, stamping and other mold control methods) has an essential difference. Additive manufacturing technology has the advantages of rapid production of complex structure products, efficient utilization of raw materials, high optimization of product structure and adaptation to personalized small batch production. In recent years, with the increasingly mature development of additive manufacturing technology, it has been increasingly applied in the field of aerospace manufacturing at home and abroad, providing a new way to realize agile, flexible manufacturing and near-net forming of complex structural products.

The key load-bearing products of China's launch vehicle body are traditionally produced by forging machine. The core stage bunching support of a certain carrier model is used to transfer the thrust of the booster to the core structure. The product dimensions are 1300 mm×630 mm×350 mm, and the main body is an inverted trapezoid structure of curved wall plate + load-bearing joint. The thinnest wall thickness of the structure is 5 mm, and the maximum wall thickness is 60 mm. The product has large size, complex structure and large difference in wall thickness, and the maximum load of a single piece under the working state is more than 200 t, which is a typical key bearing product of large size and high load complex structure. This product used to be formed by steel forging machine, forging blank mass of about 3000 kg, the mass of the body after processing is about 110 kg, the material utilization rate is less than 4%, and the resource waste is serious.

Titanium alloy Gr23 Titanium Wire has the characteristics of low density, high specific strength, high temperature and excellent corrosion resistance, etc., and is widely used in aviation, aerospace and other fields. Through the combination of Titanium 6AL4V ELI alloy material application and additive manufacturing technology, the purpose of product weight reduction and rapid manufacturing can be achieved, further improving the carrying capacity and efficiency, while overcoming the shortcomings of the "forging + machine plus" mode of complex process and long cycle, and improving material utilization and reducing resource waste.

After optimized design, the raw material of the product is changed to TC11 (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si) titanium alloy material, the material density is less than 60% of the raw steel material density, and the theoretical mass of a single product can be reduced to 60 kg, and the weight is reduced by 45.4%. This structural optimization is expected to achieve an increase of nearly 200 kg in the carrying capacity of the launch vehicle LEO, and the application effect is remarkable.

In view of the manufacturing process of titanium alloy core bundling bearing based on additive manufacturing technology, this paper expounds the process method selection and process design, and analyzes and validates the key links in the development process.