“It used to take a month for two skilled welding technicians to weld at the same time, but now it takes two days to complete welding with a Robot.” Zhang Changwu, founder and CEO of Blue Arrow Aerospace, introduced that the diameter of the nozzle of the 80-ton liquid oxygen methane engine is about More than 1 meter, the robot fully automatic laser welding can greatly reduce the manufacturing cost of the nozzle, shorten the manufacturing cycle, improve the product quality, and facilitate the mass manufacturing of products.
The nozzle is like a “honeycomb” and can resist “difficult waters”
During the launch and flight of the rocket, the temperature of the gas passing through the nozzle is between 1000-3000 degrees Celsius. “Although the temperature is not as high as the sun, the heat felt per square meter is very close to the surface of the sun.” Industry experts said that the high-temperature-resistant metal materials currently mastered by human beings cannot withstand it.
To do this, propellant is used on liquid rocket engines to cool the nozzles. By making the structure of the nozzle into an interlayer, before entering the combustion chamber, the propellant “turns” in the interlayer to take away the heat and ensure that the nozzle is not burned.
The cross-section of the sandwich nozzle is more like a honeycomb panel, with “ice” flowing in the middle and the surface to withstand the heat of the sun. The “hot water” mode poses a huge challenge to the “firmness” between the interlayers.
The method to ensure the “firmness” in engineering is to rely on welding, so that the inner and outer “two bodies” that constitute the interlayer are integrated into “one body”, but the nozzle has a complex structure, a huge shape, and high welding deformation control requirements, a little crack or bubble. It can cause damage to the nozzle of the rocket during flight, so very high requirements are placed on the welding quality.
Robots “shot” to improve quality and efficiency
In addition to sudden changes in temperature, the nozzle has to be “ravaged” by various forces – axial thrust, internal hydraulic pressure, strong vibration… Therefore, it must have sufficient structural strength and rigidity, but aerospace components must also do their best. Possibly lighter to improve engine thrust-to-weight ratio. Therefore, the nozzle should be rigid and tough while being light and thin.
Welded wall pipes are often less than 1 mm, and it is quite demanding for labor to overcome the deformation caused by welding. Many aerospace “welders” even tie sandbags with their hands to train for a long time in order to practice qualified techniques.
“In order to realize the intelligent manufacturing of liquid rocket engines, the nozzle of Blue Arrow Aerospace’s ‘Tianque’ 80-ton liquid oxygen methane engine has chosen robotic laser welding. For more than a year, our engineers have been continuously experimenting, achieving independent innovation, and at the same time Built the nozzle robot laserautomationwelding equipment. Zhang Changwu introduced that the robot “welder” does not need to use the X-ray online positioning system of the inner wall rib, which greatly reduces the complexity and cost of the equipment, and the deformation is controllable and can be directly formed.
Due to its high degree of flexibility and large reachable area, the robot “welder” can also take into account the welding of other engine components. Zhang Changwu said that with the further maturity of the subsequent process, the welding time is expected to be reduced to less than 10 hours, and the manufacturing cycle and cost are only about 1/10 of the spiral tube bundle nozzle. The whole set of process and tooling scheme has been fully declared for invention patent in 2018.
The Links: ABB 3HAC14178-1 3HAC030923-001