Nickel-based super alloy was widely used in many industrial applications due to their good structural, physical and chemical properties, such as the aerospace industry, which is one of the strategic industries. Poor cutting performance is troublesome problem for machine operators due to low accuracy and poor surface finish. In the cutting process of the nickel-base super alloy, the cutting chatter is somewhat highly unstable due to complicated mechanical vibration phenomenon, which can reduce the production efficiency and machining precision. When using cutting tools with high hardness and high brittleness such as PCBN, the blade chatter easily leads to crack. So, the principles of metal cutting, cutting chatter theory, cutting experiment and MATLAB software are adopted. These principles are used to explore the rule of the influence of cutting parameters on chatter, stability and surface quality in the process of high-speed cutting nickel-based super alloy with PCBN cutting tools. Specific studies are as follows:
- The study of chatter vibration mechanics of model in cylindrical turning. The two degrees of freedom dynamic model was established in the feeding and radial direction. It was based on the cylindrical turning processing mechanism of vibration and chatter, the criteria of the stability of cutting system were determined, and the limit cutting width of the cutting system were given in this research, and the influences of cutting vibration also were analyzed by computer simulation.
- The dynamic parameters of the machine tool cutting system were given in this research. The mechanical parameters (intrinsic frequency ωn, stiffness k, damping ratioζ) and dynamic parameters (proportional cutting force coefficient kcu, kcv) of machine tool cutting system were determined by using impulse technique modal test and orthogonal cutting tests method. The limit cutting blim in the nickel-based super alloy were predicted; the main components of machine tool also was used for the modal test, which provides the basic for determining the main vibrating system.
- The simulation study is regeneration cutting chatter model based on MATLAB/Simulink platform. This platform was used to build two degrees of freedom (2DOF), three degrees of freedom (3DOF) regenerative model of the cylindrical turning chatter, and established a method for determining the effective cutting state based on cutting parameter. The simulation model was used to predict the stability limit cutting depth of nickel-based super alloy to determine the main chatter vibration direction of cutting process. According to the results of numerical simulations, explored the process parameters such as cutting speed, feed rate and cutting depth for regenerative effect under the action of the influence law of cylindrical turning vibration characteristics.
- Experimental study on the stability and quality of the nickel-based superalloy cutting. By the test of cutting time-varying cutting depth, to test the predicted limiting cutting width of nickel-based superalloy and determine the validity of the main vibration system choice; using a single factor of cylindrical turning test and combining with the results of numerical simulation to study the cutting parameters such as spindle speed, feed rate and depth of cut to the PCBN cutting tool’s vibration characteristics of high-speed turning of nickel-base superalloy; under the condition of machining vibration, analyze the influence law of process parameters on surface roughness.
In conclusion, the researches in this topic provide a theoretical reference to improve the nickel-base superalloy processing performance and improve workpiece quality.
Evaluation of Regenerative Chatter Stability of High-Speed Turning of Nickel-based Super Alloy GH4169 using PCBN Cutting Tool.pdf (4.9% u)