The cutting technology of aviation difficult-to-machine materials and parts is a complex system engineering. In the selection of tools, new high-efficiency tools that match the mechanical properties, chemical properties and physical properties of the machined parts should be reasonably selected. Some high-speed steel cutting tools with excellent performance, carbide-coated cutting tools, ceramic and superhard material cutting tools are the first choice for efficient cutting of typical parts of aviation difficult-to-machine materials.
The following are successful cases of aviation parts processing:
(1) Machining of a certain nickel-based superalloy GH4169 ring parts. This material is equivalent to the American material grade Inconel718, with a hardness of 35-47HRC. The line speed is 400m/min, the feed speed is 0.25mm/r, and the cutting depth is 1.6mm. When cutting the knife, the new technology of oblique cutting is adopted, that is, the depth of cut is gradually reduced during the cutting process, and the effect is very good. Not only the blade is slightly worn, the shape of the blade is intact, but also efficient cutting is realized and the processing quality is guaranteed.
(2) A certain casing type parts, the material is GH2132. After solid solution and aging, the hardness is higher. The material has a high cutting temperature and a high tendency to work hardening. The depth of the hardened layer can reach 0.05mm during cutting, which will have an adverse effect on the cutting process. The material has high strength, high plasticity and toughness, and large surface residual stress. In the cutting process, the cutting depth and feed rate should be selected reasonably so that the cutting edge cuts under the hardened layer, otherwise it will accelerate the tool wear. The part has a large diameter and thin wall thickness, and the rigidity of the part is not strong, which leads to an increase in cutting force. Vibration occurs during processing, which causes deformation of the part, and the surface of the part is prone to oscillating waves. In the cutting test, multiple layered processing is carried out according to the depth of cut of the workpiece.
Test equipment: five-axis CNC milling machine, the spindle speed of the machine tool can reach 1 800r/min, and the feed speed can reach 500-700mm/min.
Test tool: Use solid carbide end mills with a diameter of 12mm, 4 equidistant teeth, an entering angle of 90º, a shank diameter of 12mm, a helix angle of 45º, a blade length of 26mm, a knife length of 75mm, TiALN coating, and high-pressure cooling . The 45º helix angle can effectively increase the chip holding space. The cutting edge and helix angle of the milling cutter are reasonably optimized, which reduces the cutting force and prolongs the tool life. The surface quality of the parts meets the technical requirements.