Modeling and optimization of the milling process of compressor rotors

螺杆式空气压缩机的效率在很大程度上取决于其成对螺杆转子之间的间隙。间隙不足会导致运行中成对转子之间的干涉，间隙过大会导致齿隙和效率损失。虽然转子间隙经过精心设计以避免此类问题，但实际转子间隙可能会因各种因素而偏离其标称设计，而制造误差是导致这种偏差的主要因素。当前确定制造误差对转子轮廓偏差的贡献并在设计阶段对其进行补偿的实践涉及许多昂贵的试验和错误，这些试验和错误可能不会导致转子及其制造过程的最佳设计。替代地，用制造过程的建模和仿真代替物理试验可以导致显著的成本节约和提高压缩机效率。该项目的目标是通过开发基于物理的转子铣削过程模拟来识别和最小化由于制造误差而导致的转子轮廓偏差。开发的模拟将使用该过程的运动学模型来预测基于刀具轮廓和加工参数的加工转子轮廓的形状。此外，将使用虚拟加工系统（VMS）模拟过程中产生的力和振动。然后，将使用过程模拟来确定最佳加工参数，这些参数将导致加工轮廓形状的最小偏差，而不影响生产率。VMAC当前的转子轮廓将被用作案例研究，以验证开发的模拟在减少转子铣削过程中的制造误差的有效性。

The efficiency of rotary screw air compressors is highly dependent on the clearance between their paired screw rotors. Insufficient clearance leads to interference between the paired rotors in operation, and excessive clearance leads to backlash and loss of efficiency. Although rotor clearance is carefully designed to avoid such problems, the actual rotor clearance can deviate from its nominal design due to various factors, and manufacturing errors are among the major contributors to this deviation. The current practice to determine the contribution of manufacturing errors to rotor profile deviations, and compensating for them in the design stage, involves numerous costly trial and errors which may not result in the optimum design of the rotor and its manufacturing process. Alternatively, substituting physical trials with modeling and simulation of the manufacturing process can lead to substantial cost savings and improving compressor efficiency. The objective of this project is to identify and minimize the deviation of the rotor profile due to manufacturing errors by developing physics-based simulations of rotor milling processes. The developed simulations will use the kinematic models of the process to predict the shape of the machined rotor profile based on the tool profile and machining parameters. In addition, forces and vibrations that arise during the process will be simulated using a Virtual Machining System (VMS). Process simulations will then be used to determine optimum machining parameters that would lead to minimum deviations in the shape of the machined profile without compromising productivity. The current rotor profiles at VMAC will be used as case studies to verify the effectiveness of the developed simulations in reducing manufacturing errors in rotor milling processes.