At present, the domestic aviation engine manufacturing enterprises almost all adopt artificial grinding into the exhaust side of the manufacturing of titanium alloy compressor blades and fan blades and guide vanes, the blade inlet edge thickness difference is large, poor consistency, line type is not accurate, the leaf quality is not high. With the steam turbine industry gradually adopt CNC Abrasive belt grinder blade machining surface and the exhaust side of aero-engine manufacturing enterprises have also proposed the use of CNC Abrasive belt grinding into the exhaust side, eager to be able to solve the problem by CNC Abrasive grinding the exhaust side of aero engine blade manufacturing. By analyzing the characteristics of the technology of titanium alloy blade and the analysis of different blade NC belt grinding production practice, process testing, verification, put forward several necessary conditions for CNC Abrasive Belt Grinding and the corresponding countermeasures to realize the aviation titanium alloy blade.
For aero engine, the core machine once finalized, the subsequent development mainly through the use of new technology, new design, increase the fan diameter, increase booster compressor series, improved high pressure compressor, high-pressure turbine blade design, improve the high pressure turbine blade materials and coating high-temperature performance to improve the efficiency of components and engine thrust. The manufacturing process of aero-engine blade and steam turbine blade is very different. The former mainly adopts the molding method, while the latter mainly adopts the removal material method. The machining of aviation titanium alloy blade is mainly the process of inlet and exhaust, and the processing difficulties of numerical control belt grinding have the following main aspects.
(1) the air inlet and exhaust blades of the aircraft are very thin, and the large fan blades are only about R0.3mm. Some of the small compressor blades even reach the R0.1mm level. This makes it necessary to use very small contact force to grind the abrasive belt grinding, otherwise it is difficult to ensure the accuracy of the surface. This puts forward high requirements for the contact force control of the belt grinding device.
(2) uneven grinding allowance. Titanium alloy compressor blade forging and superplastic forming of fan blades by milling or cutting into the exhaust side line general forging flash, and then the exhaust side of the grinding and polishing processing, the processing features make the exhaust side fillet part machining allowance is not uniform, as shown below: the red part is rough outline, arc part the theory of curve into the exhaust side.
(3) deformation of blade. This problem and the uneven grinding margin is the same problem, titanium alloy blade forging and superplastic forming blades are at a certain temperature to complete the deformation by residual stress are the deformation force effect, especially the compressor blade, and blade deformation magnitude of inlet and outlet edge thickness on the same dose level, reaching more than 0.1mm, and the general aviation blade surface space error by about 0.05mm is too big, must be corrected.
(4) the datum problem, the surface alignment and the consistency after the blade is clamped. Precision blade and superplastic forming blade surface accuracy is very good, but still a rough benchmark, which is compared with the steam turbine blade milling benchmark is still coarse. As mentioned above, this clamping position error is equivalent to the blade deformation error in order of magnitude, which is an important factor that can not be ignored, and must be solved by correcting the coordinate system. In addition, the exhaust side grinding, cooling condition is not good, very thin edge radiation condition is not good, easy to produce the blade into the exhaust side of ablation, it also gives blade edge grinding difficult; for superplastic forming of fan blades, in addition to the exhaust side, grinding polishing needs surface, there are the problem of surplus is not uniform, deformation error etc.
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