Based on the many advantages of arc additive manufacturing, this technology is called a low-energy, sustainable and green manufacturing technology, which is especially suitable for additive manufacturing of difficult-to-process and precious metal parts. The manufacturing process of arc additive composite milling and cutting materials has been applied in aerospace and other fields, and has unique advantages in the manufacture of lightweight and large-scale integral wall panels.
In the manufacture of some large-scale metal structural parts, the European Space Agency and Cranfield University in the UK used MIG arc additive manufacturing technology to manufacture large-scale frame components such as titanium alloy aircraft wing spars and landing gear support outer ribs. Hours of kilograms, welding wire utilization rate of more than 90%, the product's forming time only takes 1 hour, product defects are few, they manufactured 1.2 m long titanium alloy aircraft wing parts, the whole process only takes 37 hours. Lockheed Martin (UK) used ER4043 welding wire as the raw material to develop a large conical cylinder with an arc additive method, which is about 380 mm high; Bombardier uses arc additive technology to manufacture directly on a large flat plate The large aircraft ribs are about 2.5 m long and 1.2 m wide. Norwegian NTi uses rapid plasma deposition (RPD) technology to provide titanium alloy parts for the Airbus A350 aircraft. Domestically, the micro-casting and forging composite 3D printing equipment developed by Wuhan Tianyu Intelligent Manufacturing Co., Ltd., which integrates arc / plasma arc / laser, can print metal range 5 m × 2 m × 1.5 m, covering large, medium and small A variety of complex materials with different specifications.
Foreign institutions have applied arc additive to the manufacturing of integral wall panels, and gradually moved from the prototype stage to the practical stage. The integral siding structure is usually composed of skin and reinforcement ribs, etc. It not only has complex shape characteristics, but also has a staggered internal structure. If the traditional integral milling process is used, most of the material needs to be removed from the thicker substrate, and the processing efficiency is low. If composite manufacturing is adopted, the rib structure is directly deposited on the thin substrate by arc addition, and then supplemented with a small amount of milling material to improve its forming accuracy and surface quality, the material utilization rate can be from 10% to 20 % Is increased to more than 80%, while greatly improving processing efficiency and reducing costs, providing a new type of high-efficiency, high-quality, low-consumption and low-cost process for the manufacture of overall siding structures, thus vigorously promoting resource conservation and efficiency Under the background of manufacturing, it has broad application prospects.
For the described composite manufacturing process, although the milled cut material largely compensates for the inherent deficiencies of the arc added material in terms of geometric size and surface quality, the arc added material belongs to the hot processing process, and the milled cut material belongs to the cold processing process. There are obvious macro and micro error transmission processes in the alternating cycles of cold and hot processing, which restricts the development of the composite manufacturing process to high precision and high performance.
The so-called macro error transmission refers to: in the arc additive, due to uneven temperature distribution and heat accumulation, the solidification and cooling of each part of the part is inconsistent, resulting in residual stress and macro deformation of the part. Research on its control. The macro deformation of the part will be transferred to the subsequent milling and cutting material, resulting in over-cutting or under-cutting. At the same time, as the material is continuously removed, it will cause partial release and redistribution of residual stress and cause secondary deformation of the part. It can be seen that the macro error transmission mainly determines the dimensional accuracy and geometric accuracy of the parts.
The so-called micro error transmission refers to: the arc-additive due to its laminated manufacturing principles and complex heat input characteristics, the size, morphology and residual heat of the resulting deposited parts are significantly different from conventional parts; the size of the deposited parts , The appearance error and the machining residual heat will be transferred to the subsequent milling and cutting materials, which will have a series of effects on the machining allowance, cutting temperature, tool wear, etc., which will affect the surface quality of the parts. It can be seen that the transmission of microscopic errors mainly determines the surface quality of parts.