The temperature process analysis and control on laser-assisted milling of nickel-based superalloy

Nickel-based alloys of Inconel 718 are well-known for their excellent properties of high-temperature hardness, mechanical strength, and wear resistance and are currently popular and applied in aerospace industry, such as the manufacturing of aero-engine turbine disks and compressor disk. Laser-assisted milling (LAML), which uses laser to locally heat the workpiece to improve the machinability of the material, has the advantage of increasing machining efficiency, reducing tool wear, and improving machining quality. In LAML, laser preheating temperature is the most important parameter influencing laser heating effect; however, constant laser energy commonly used in experiments cannot provide a stable preheating temperature. Therefore, temperature feedback control method is used in LAML and composite simulation models are established to simulate the temperature field and cutting process. The composite simulation models contain laser preheating temperature model, temperature feedback model, temperature difference prediction model, and cutting process model. Finite element method and neural network calculation method are used in building the model, which can be used to get the temperature difference, and then through monitoring to control the temperature of the laser heating. The simulation results show that the laser energy and the laser moving speed are the main factors affecting the laser preheating temperature, the difference between cutting area temperature and monitor temperature. A LAML experiment system is set up; cutting force and cutting chips are obtained through experiments. The simulation results express a good agreement with the experimental results, thus demonstrating the feasibility of the temperature-monitoring laser heating system and capabilities of LAML in fabricating difficult-to-machine parts for industrial implementation.