Research on high efficiency machining process of titanium alloy integral impeller

As a typical complex part in manufacturing industry, the overall impeller is widely used in high-tech fields such as aviation, aerospace, modern turbomachinery, compressor, turbomachinery and rocket launch propulsion device. With the progress of material science and machining technology, titanium alloy integral impeller has gradually become the mainstream material because of its excellent mechanical properties. However, the difficult machinability of titanium alloy and its complex blade structure bring many challenges to the machining process. The purpose of this paper is to discuss the efficient machining process of titanium alloy monolithic impeller in order to improve the machining efficiency, machining quality and reduce the manufacturing cost.
Difficulties in machining titanium alloy integral impeller
The main difficulties faced in the processing of titanium alloy impeller include the following aspects:
Material properties: titanium alloy (such as TC4) cutting performance is poor, small modulus of elasticity, high hardness, cutting process is prone to deformation, sticking knife, let the knife and other phenomena, affecting the surface quality and geometric accuracy.
Complex surface: impeller blade shape is complex, mostly free-form surfaces, curvature changes, frequent changes in the cutting force during the machining process and the direction is uncertain, easy to produce vibration, affecting the surface quality.
Insufficient blade rigidity: long and thin blades have poor rigidity in the machining process, and are prone to elastic deformation during the finishing process, which makes it difficult to guarantee the machining accuracy.
High processing costs: high-performance four and five-axis linkage of CNC machine tools are expensive, long machining cycle, low efficiency, increasing the manufacturing cost.

High-efficiency machining process research
1. Tool selection and path planning
Tool selection: for the difficult machining of titanium alloy, SKG fast feed milling cutter specially developed for titanium alloy is used for roughing, SKG milling cutter adopts small deflection angle and low resistance S-type insert, the cutting force is mainly in the axial direction, and the outer periphery of the tool adopts the avoidance of hollow structure, which is suitable for the impeller's thin-walled structure and the characteristics of the special shape processing, and it can improve the roughing efficiency and reduce the cost of tool use.
Path planning: At the rough grooving stage, a top-down grooving method is adopted layer by layer along the direction of the runner to realize the amount of retention on the blade by controlling the machining area of each layer between the runners to ensure the rigidity of the blade. In the finishing stage, point milling is used to reasonably determine the finishing allowance of the blade, select appropriate finishing tool parameters, reduce the cutting force, and ensure processing stability and precision.
2. Optimization of milling parameters
Orthogonal experimental method: use orthogonal experimental method to study the characteristics of multi-axis milling of titanium alloy, and analyze the effects of milling speed, feed per tooth, milling width, milling depth and tool inclination angle on the milling force and surface roughness. The regression prediction model of five-factor milling force and surface roughness of TC4 titanium alloy milling by carbide ball cutter based on emulsion as milling fluid is established and its rationality is verified.
Simulation and experimental validation: The calculation of tool axis vector and the visualization of toolpath are completed by using MATLAB with MAX-PAC and UG joint simulation. The feasibility and superiority of the optimized toolpath trajectory are verified through simulation and actual machining test.
3. Multi-objective optimization
Roughing optimization: Aiming at the problem of high cost and low efficiency of titanium alloy overall impeller roughing, establish a multi-objective optimization mathematical model with the minimum tool consumption and the highest milling efficiency as the objective function, and solve the multi-objective optimization problem of the Pareto optimal solution frontier with the improved algorithm toolbox.
Finishing optimization: for the requirements of high surface quality and high efficiency of titanium alloy impeller finishing, establish a multi-objective optimization mathematical model with optimal surface quality and highest milling efficiency as the objective function, and improve the machining quality and efficiency through the optimization algorithm.
Through the research on the efficient machining process of titanium alloy integral impeller, this paper proposes a comprehensive solution from tool selection and path planning, milling parameter optimization to multi-objective optimization. These measures effectively improve the machining efficiency and machining quality of titanium alloy integral impeller and reduce the manufacturing cost. The research results have high engineering application value and provide technical support for the machining of difficult-to-machine material parts with complex structures. With the continuous progress of technology, the efficient machining process of titanium alloy integral impeller will be further improved and optimized in the future.