Research On On-line Inspection And Error Compensation Method For Integral Impeller

As one of the most typical examples in complex surface parts, the integral impeller is widely used in aerospace, aviation, electric power, energy and other industries. It is generally machined by5-axis CNC machine tool because of the complex shape. However, because of thickness of the blade and weak rigidity, the deformation will occur in machining, and the machining accuracy of the blade is influenced. On-line inspecting and compensating technology is an effective method to improve the blade machining efficiency. In this thesis, in order to improve the integral impeller machining accuracy, the on-line inspection and error compensation method is studied for the integral impeller on the5-axis NC machine tool. The main work is as follows:(1) The analysis of the machine tool geometric error and the pre-traval error. The model of the geometric error is established after analyzing the NC machine tool geometric error of each axis. Then the on-line inspection station is set up based on the5-axis CNC machine tool. After debugging the system, the model between the pre-travel error and the influence factors is established by the measurement experiments with the standard ball.(2) On-line inspection of the blade and surface modeling. After planning the detection path of the blade, the blade is inspected with the detection program, and the machine tool geometric error is eliminated firstly. According to the theory of B-spline surface, the actual machined blade surface is modeled with the blade data after geometry transformation without pretravel error.(3) Evaluation and compensation of the blade machining error. The machined blade surface is compared with the theoretical surface firstly. Along the normal direction of the measuring point on the theoretical surface, one point on the machined blade surface can be found. The distance between the two points is the machining error. The blade data after composition is obtained using mirror symmetry method, and the surface with new data is generated.(4) NC machining experiment. According to the new blade surface, the NC machining program is carried out with the UG software. The program is simulated using the VERICUT sofeware. The machining accuracy of the blade is inspected after machining on the5-axis machine tool. After comparing with the blade machining accuracy before compensation, it proves the error compensation mentioned in this thesis is effective.