Large propellers generally include hubs, blades, blade roots, edging, blade and leading edges. The manufacture of super-large propellers involves many difficulties such as casting technology (to prevent cavitation) and machining techniques, especially complex shapes. High-precision propellers require high-end multi-axis linkage machine tools!
Some time ago, CCTV reported that the Chinese aircraft carrier Liaoning replaced the propeller data, which indicates that China has completely achieved breakthroughs in the manufacturing technology of a large-scale ship propeller precision welding, manufacturing and installation.
The propeller technology of large ships has been a barrier to the development of large ships in China for quite a long time. Refer to the US Bush aircraft carrier propeller data: Nimitz CVN 77 Bush aircraft carrier propeller diameter 6.4 meters, an aircraft carrier has 4 propellers, each propeller has 5 blades, each blade weight is 30 tons, It is estimated that the total weight of the propeller will reach 600 tons. Then the rotor of China's Liaoning aircraft carrier has a diameter of at least 4.5 meters and a total weight of 400 tons.
So how difficult is the manufacturing technology of the large aircraft propeller propeller?
First, break through the material barrier, due to the long-term operation of the sea in a highly corrosive environment. Then the choice of materials will be the first point to break through. Can not use pure steel, because it can not withstand long-term corrosion, according to international practice, most of the large ships and aircraft carriers use a special copper alloy, that is, copper is the main thing to add manganese, nickel and other metals to improve the alloy The rigidity is not subject to pressure for a long time, and the copper is easily deformed. Slight deformation is nothing. If it reaches a certain range, it will have a greater impact on the accuracy of the orbital navigation. In addition, it will increase noise.
Secondly, multi-axis propulsion technology, the general aircraft carrier will install 4 propellers, in order to improve the turning efficiency of the aircraft carrier large warships. As the saying goes, the good ship is a good turn, but for a large-scale aircraft carrier of 100,000 tons, turn a corner. Not so easy, especially where the water is not very spacious, so the surface of the propeller must be accurately calculated and machined.
Another important point is the manufacturing and processing technology of propeller propellers. In the past, the smaller blades of our country were built by hand. Now, due to the breakthrough of the technology of China Zhenjiang Zhongchuan Wärtsilä Propeller Co., Ltd., the 7-axis five-link machine tool has been developed. The maximum diameter of the processing has exceeded 12.5 meters and 160 tons. The propeller manufacturing technology, the majority of the propellers of the Nimitz-class aircraft carrier, is more than enough to manufacture the most advanced Ford-class nuclear-powered aircraft carrier in the United States. In the past, two workers worked 24 hours a day, and 17 or 8 days to build a small and medium-sized propeller. Now, on a precision CNC machine, programming takes only 3 days to complete.
Therefore, it is no exaggeration to say that the large-scale marine propellers are black technology in the machining industry. The countries that can master this technology are few and far between in the world.
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