Titanium alloy is an important structural metal that was developed in the 1950s. It is widely used in aviation equipment manufacturing due to its high strength, good corrosion resistance, and high heat resistance. It is mainly used in the production of engine compressors. However, titanium alloy plate polishing has its own unique physical and chemical properties, so it is difficult for the quality and performance of the materials after processing to change well, resulting in a large loss in the production process, and it will also affect the safety of the engine.
The polishing process of titanium alloy plates for aviation engines, the engineering detection method of ablation (injury), and the surface state of the blades after ablation (injury), analyze the causes of ablation (injury), introduce a series of processing tests to avoid ablation (injury) problems, and through repeated experiments on various processing methods and parameters, summarize the reasonable processing methods and parameters to avoid the problem of ablation (injury) of titanium alloy plate polishing, and summarize certain experience for the high-quality and efficient processing of titanium alloy plates.
Polishing process:
The blades to be processed are made of materials marked as TC4. The length and width of the blade surface structure are 110mm and 35mm, respectively. During the processing, the blade basin, blade back, inlet, and exhaust edges, and the transition between the surface and the mounting plate need to be polished. The equipment used is a grinding wheel polisher. To meet the roughness and shape technical requirements for the surface and edge in the design drawing, the polishing process should include: rough polishing process, semi-finishing polishing process, and fine polishing process.
1. Rough polishing of the blade surface
Rough polishing (commonly known as shaping and residual removal) is the preparatory work before fine polishing of blades. A 46# grit silicon carbide grinding wheel is used to remove the excess left by machining on the blade surface and to trim the shape of the blade surface. The roughness of the rough polished blade body surface is below Ra3.2μm. Under normal circumstances, the rough titanium alloy plate polishing margin is 0.08mm.
2. Semi-finishing polishing of the surface
Semi-finishing polishing is the preparatory work for fine polishing. Semi-finishing polishing is to polish the profile with a wool felt wheel and 100#~120# silicon carbide sand. The purpose of semi-finishing polishing is to further polish the profile, eliminate ripples, and reduce the roughness Ra value. The semi-finishing blade profile has a margin of 0.02mm. The surface roughness of the semi-finished blade body is Ra0.8μm.
3. Profile surface finishing
Fine polishing is a process of finishing the profile based on semi-finishing polishing to achieve the specified roughness and technical requirements of the drawing and dimensional accuracy requirements. The grinding and polishing of the blade profile is a dry grinding process without coolant.
Titanium alloy plate profile surface polishing, ablation detection method, and cause:
1. Titanium alloy plate profile surface polishing ablation detection method
Titanium alloy plate material is relatively soft. The method for engineering detection of the ablation phenomenon of the blade profile grinding and titanium alloy plate polishing of this material is to use the surface weak corrosion test method. The phenomenon reflected is the appearance of tiny corrosion pits on the surface of the blade profile.
2. Causes of ablation during the polishing of the titanium alloy plate surface
Based on the actual understanding of the blade surface titanium alloy plate polishing process and the actual situation, it can be found through analysis that most of the sand particles that fall off are generated on the upper part of the grinding wheel, which will be subjected to grinding pressure during the grinding process, so the titanium alloy material will have a strong softening tendency, and thus welding will occur instantly in this case.
