First, let’s take a look at PBF’s metal melting 3D printing technology based on a metal powder bed. PBF is considered a direct metal 3D printing technology. This type of technology uses laser or electron beam as a heat source to melt metal powder layer by layer. Solidified into the shape of the part.
Compared with metal 3D printing technology, PBF is currently the most widely used metal 3D printing technology. Including General Electric’s US$1.4 billion acquisition of Concept Laser and Arcam, the market’s attention has also been focused on metal powder bed melting, including two processing methods, laser melting and electron beam melting. At present, laser melting is more widely used.
Due to the realization of very complex product manufacturing, PBF technology not only makes the manufacture of complex products more feasible, but also creates greater comprehensive economic benefits around the product life cycle.
In terms of power equipment, the products achieved by PBF technology do not remain in the concept development stage, but have entered space with rockets and spacecraft, as the aircraft soars in the sky, and play a “four or two strokes” in the field of power generation. Benefit magnification. The next generation of products created by 3D printing have greatly improved the level of human use of resources, and all this has come to us.
In this regard, the well-known GE 3D printed fuel nozzle  has a top structure only the size of a walnut, but there are 14 precise fluid channels inside. The 3D printed fuel injector is a precise whole, and the original 20 parts are manufactured as one part. The weight of the new nozzle is 25% lighter than the previous generation, the durability is 5 times that of the previous generation, and the cost-effectiveness is 30% higher than the previous generation. GE’s Auburn plant delivered a total of 8,000 fuel nozzles in 2017 with more than 40 3D printers.
As of the end of 2018, the total number of 3D printed fuel nozzle heads completed by the factory has exceeded 33,000. However, it is worth noting that, unlike the traditional processing technology that ranks among the track of PK production efficiency, GE’s greatest benefit from fuel nozzles is not the fuel nozzles themselves, but LEAP and GE9X engines equipped with fuel nozzles. , 3D printing is promoting aero engine innovation, and GE has initiated the layout of the commanding heights of next-generation aero engine technology.
There are numerous similar success stories, except for the well-known SpaceX, NASA, GE, Siemens, etc. through 3D printing that are constantly breaking the performance limits of next-generation spacecraft, commercial aircraft, gas turbine generators and other products.
In 2020, Europe, which is not to be outdone, is also catching up. The ESA European Space Agency’s full-scale 3D printed copper alloy thrust chamber passed the first hot test. Additive manufacturing reduced the number of thrust chamber parts from hundreds to three, shortening The production time is reduced, the cost is reduced, and the competitiveness of the liquid propulsion engine in the European launch vehicle is significantly improved. Internationally, the full-size thrust chamber has a 3D printed copper alloy lining, which has an integrated cooling channel, and its outer layer is a high-strength jacket created by cold air spraying. Not only that the manifold and integral fuel injection of the thrust chamber are also 3D printed.
The components of micro gas turbine engines are complex and miniaturized. Previously, this field still had to rely on foreign products and technologies. Shenzhen Yidong Aviation and Anshi Asia-Pacific successfully developed two fully 3D printed micro turbojet engines, the NK-10 with 10kg thrust and the NK-50 with 50kg thrust. In 2018, the over-temperature test above 1200℃ has been completed. The indicators meet the design requirements, and the maximum speed in the test is higher than 140,000 rpm.
The development of the domestic aerospace industry through 3D printing has also shown a springing up trend. In 2019, China’s Deep Blue Aerospace liquid oxygen kerosene engine once again carried out a long-distance test run in the thrust chamber and achieved complete success. In terms of thrust performance, Deep Blue Aerospace optimized the design of main functional components and adopted a large number of 3D printing processes to achieve a technical leap from 95% to 99% of the thrust chamber efficiency of domestic liquid oxygen kerosene rocket engines, reaching the international advanced level.
Blite undertook the metal 3D printing of the two parts of the engine injector shell and thrust chamber body for this test run. Engine injector shell and thrust chamber body are the key components of aerospace engine. The use environment is harsh. There are more than 100 cooling channels inside the parts. The traditional milling and welding processes are not only used for long manufacturing cycle, high cost, but also for parts performance. It is also difficult to be guaranteed.
In the automotive field, GKN and automobile manufacturer Porsche developed new applications for new electronic drive powertrains through metal 3D printing. Based on the characteristics of powder bed metal melting 3D printing technology, GKN has developed a specific steel material for higher design freedom, more efficient and more integrated power system. This steel material can withstand high wear and load, combined with 3D printing The realized function integration further reduces weight.
On the other hand, Porsche’s engineering department is studying how to implement new materials in its electronic drive power system. Using structural optimization technology combined with GKN materials, Porsche has realized the unique design of the differential (including the ring gear). Through this combination of gear weight reduction and rigid shape, more efficient transmission is achieved.
PBF technology is still giving birth to the development of next-generation heat exchangers. In 2019, GE announced that it will cooperate with the University of Maryland and Oak Ridge National Laboratory to develop UPHEAT ultra-high-performance heat exchangers. The development plan will be completed within two and a half years to achieve more efficient energy. Conversion and lower emissions. GE hopes that the new heat exchanger will operate at temperatures exceeding 900°C and pressures above 250 bar, and the thermal efficiency of the supercritical CO2 power cycle will increase by 4%, which will increase power output while reducing emissions.
In terms of materials, this new type of heat exchanger will use a unique high-temperature, crack-resistant nickel-based superalloy, which is a material designed by the GE research team for the additive manufacturing process. The heat exchanger includes multiple additive manufacturing methods that make the fluid channel smaller in size, have a thinner wall and form a fluid path, and have intricate shapes. These heat exchangers cannot be manufactured using previous traditional manufacturing methods.
In the field of power generation, both GE and Siemens have broken their own net efficiency records through 3D printing manufacturing technology. Among them, GE defeated its previous design with a combined cycle efficiency of 64% in the test at the Greenville, South Carolina plant. GE attributed the improvement of HARriet efficiency to “combustion efficiency breakthroughs brought about by continuous innovation”, and the innovations here are inseparable from the many key components of gas turbines manufactured by 3D printing technology. GE uses metal 3D printing technology to manufacture the optimized combustion system components to achieve more complex geometries. This improves the premixing of fuel and air in the HArriet gas turbine, thereby maximizing the power generation efficiency of the gas turbine.
In addition to molds with conformal cooling channels, tools with complex internal cooling structures, fuel nozzles with internal cooling channels, and engine combustion chambers, high value-added products achieved through PBF, the manufacturing of complex lattice structures becomes PBF metal 3D printing technology Another major feature application. In 2019, the world’s first 3D printed full-lattice entire star structure was successfully put into orbit. The Qiancheng-1 entire star structure was developed by the Mechanical System Division of the General Department of the Fifth Aerospace Academy. It adopts a lightweight three-dimensional lattice structure for additive manufacturing. The design method is designed, and the whole star structure is integratedly prepared by aluminum alloy additive manufacturing technology.
The weight of the traditional micro-satellite structure is about 20%, and the frequency of the whole satellite is generally about 70 Hz. The weight of the entire satellite structure of the Qiancheng-1 microsatellite has been reduced to less than 15%, the entire satellite frequency has been increased to 110 Hz, the number of entire satellite structure components has been reduced to 5, and the design and preparation cycle has been shortened to one month. The size of the entire satellite structure exceeds the envelope size of 500mm×500mm×500mm, which is currently the largest integrated satellite structure for additive manufacturing.
In addition, the 3D printing lattice structure can also be applied to the manufacture of high-strength compressor parts. The main part of the lightweight, high-strength compressor component has an internal area with a dot matrix structure. The dot matrix structure is realized by 3D printing. The main body also realizes an internal fluid delivery channel through 3D printing. The fluid delivery channel is used to allow lubricating oil to flow. Through the main part of the compressor components. However, the combination of lattice and 3D printing is not as easy as imagined. In this respect, simulation software is needed to improve the success of modeling and manufacturing. Based on multi-scale algorithms, users can use equivalent homogenization technology to perform finite element analysis on lattice structures. .
In addition, the equivalent material parameters of the heterogeneous lattice structure are extracted. After the macro-mechanical analysis of the homogenized equivalent solid model, detailed stress verification of the cell structure can be performed through local analysis. Design, software and materials help release the potential of 3D printing. In terms of materials, not only high-temperature alloys and aluminum alloys have achieved a leap in the performance of parts through the PBF process. Motors with cast copper rotors can help ordinary induction motors to effectively reduce the rotor loss of the motors. , Other metal materials such as 3D printing copper metal process.
It is expected to solve the challenges of casting and brazing of cast copper parts for electric vehicles, replacing casting and brazing, and realizing more economical, complex and efficient production of copper parts, which is expected to be used in the manufacture of parts such as rotors, radiators, inductors, etc. .
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