Technical breakthrough! Superhard grinding tools CNC machining of complex profile blades is possible

According to domestic media reports, a machine tool innovation research institute achieved breakthroughs in aero-engine blade production. Together with a local machine tool company, they successfully developed a 4-axis linkage and 5-axis linkage 4-array blade grinding and polishing machine, 1 It can process 4 blades at the same time, the processing efficiency and precision are much higher than imported machine tools, and the performance is at the international advanced level, which solves the world problem of difficult processing of complex profile blades.

This paper makes a background analysis based on public information at home and abroad. With the rapid development of China's aviation industry, the production of high-performance aircraft engines, gas turbines and other equipment has increased dramatically. As a key component of these devices, the domestic demand for aero-engine blades and gas turbine blades has also multiplied. It can be said that the processing quality of the blade has a significant impact on the performance and life of the machine.

Because the blade is in the harsh working environment such as high temperature and high pressure for a long time, and it is subjected to the alternating stress of centrifugal force, water or steam, it is made of high hardness and high strength material to ensure the reliability and working life of the blade. In particular, the new generation of aero-engine blades meet the performance requirements, which not only imposes extremely severe precision on the machining accuracy of complex curved surfaces, but also has high requirements on surface roughness.

The general aero-engine blade processing procedure is as follows: after the high-temperature casting of the blade, the surface shape and size are obtained by a high-precision CNC milling machine, and the surface is removed by a finishing process combining abrasive belt polishing and cloth wheel polishing. Residual tool marks, correcting the shape accuracy of the surface and reducing the surface roughness. Due to the lack of special machine tools, the follow-up work of some large, critical and complex blade finishing operations still relies mainly on the manual operation of skilled workers.

Manual polishing not only has low processing efficiency, processing precision is difficult to guarantee, but also endangers the health of workers. More importantly, the quality of manual polishing is extremely high on the quality of workers. In the current situation where the number of highly skilled workers is seriously insufficient, the production time of leaves is relatively high. Long, cost is high, can not meet the low cost, the urgent need to mass produce aero engine blades.

China is the superpower of superhard materials production in the world today. The world's hardest synthetic diamond production reached 16.6 billion carats in 2016, accounting for 90% of the world's total output. The world's second hard cubic boron nitride (but high temperature resistance) And chemical stability is much higher than synthetic diamond. The production in 2017 is about 550 million carats, accounting for about 70% of the world's total output. Using the superhard mechanical properties of synthetic diamonds, grinding and polishing difficult-to-machine materials such as cemented carbide, gemstones, ceramics, titanium alloys, etc., have proven to have unique advantages.

As the domestic super-hard materials industry has widely used China's original six-sided top press technology to mass produce synthetic diamonds, its low price makes people can't believe it. There is information that the domestic 1 carat synthetic diamond is priced at only 0.3 yuan. At the same time, with the rapid breakthrough of China's multi-axis CNC precision machine tool technology, it is possible to CNC machining complex profile blades with super-hard abrasives. Due to the high performance, high life expectancy and high cost performance of domestic high-performance super-hard materials, the price of domestic 5-axis CNC machine tools is only 1/3 of the imported equipment, and the blade superhard abrasive CNC grinding machine is combined with the two. Cutting and polishing technology is an advanced and reasonable production technology route.

A certain area has a domestic leading advantage in the production of low-cost CNC machine tools. A certain airline relies on its advantages in machine structure design and analysis to carry out a large number of improved design of CNC grinding machine tool structure and transmission system, combined with the independent development of Beihang. Rectangular array turntable and oscillating head, successfully developed a 4-axis linkage and 5-axis linkage 4-array blade grinding and polishing machine, each of which can process 4 blades at a time, and its finishing efficiency and speed have been significantly higher. In the efficiency of CNC milling, the machining accuracy is much higher than that of the current CNC milling machine with a value of 6,7 million yuan. The measurement results show that the accuracy of the blade shape accuracy of the four arrays is excellent. Only 10% of the design tolerance.

In the next step of the R&D plan, a 100-axis CNC grinding machine that processes 100 blades at the same time is being developed, which will further expand the cost advantage compared with CNC milling, and the cost of machine tools, land, personnel, etc., which are expected to be used for blades and other parts. Reduce to below the current 10%. At the same time, in order to replace the heavy labor of the blade polishing workers, Zaozhuang Beihang Machine Tool Innovation Research Institute has also developed a variety of 8-10-axis blade and impeller CNC polishing machine tools. The blades of complex curved surfaces have not been seen after polishing by the polishing machine. The processing marks are basically close to the mirror surface, and the new grinding and polishing technology can be used instead of the manual polishing production line.