Research On Technology Of Integral NC Machining For Runner Of Pelton Turbine

Over the years, manufacture of Pelton runner mainly adopts cast grinding, welding,riveting technology and means to carry out processing. Although the methods andprocesses are simple, the production is efficiency and technology level are relatively low.They also can not guarantee the dimensional accuracy and quality of the runner so that therunner’s service life and operating efficiency are greatly affected. With the rapiddevelopment of CNC machining technology and equipment, the manufacture of Peltonrunner has begun to shift from the split to the overall. By using special five-axis CNCmachine tools with NC rotary table on the integral NC machining to Pelton runner inabroad，it is not only improves the production efficiency and dimensional accuracy but alsoenhances product competitiveness and economic benefits. For the domestic wheel bucketprocessing technique is backward, lack of special machine tools and the three axis CNCmachining equipment general situation, studying on new methods, new technology andnew technology of three-axis CNC machine tools with NC rotary table on four-axisintegral NC machining for Pelton runner is undoubtedly to have great realistic significanceand wide range of application in the future.Because of complex surface, compact structure and poor openness, it’s easy to havethe collision, interference, over-cut and so on in the processing of Pelton runner so that thehe realization of integral NC machining for Pelton runner is more difficult. Therefore,according to the structural characteristics and processing requirements of Pelton runner,when studying on three-dimensional digital modeling method, four-axis integral NCmachining process、tool structural design and finite element analysis、CNC machining toolpaths’ generation, machining simulation, NC Programming and so on for Pelton runner,eventually it forms a more perfect integral NC machining technology.The specific studies are as follows:1, Taking a certain the two-dimensional product drawings of a certain type of Peltonrunner for the foundation, the basic principles of the relevant curves and surfaces toestablish three dimensional digital model of the Pelton runner with UG/CAD software.2, Analyzing the structural characteristics of the Pelton runner and processingdifficulties, studying on four-axis NC machining characteristics and processing methods,to choose the reasonable cutting methods and tool paths, develop integral NC machining process and parameters for the Pelton runner.3, According to the process characteristics and requirements of the surface finishingPelton runner, design large cantilever and high stiffness shank structure to avoid collision,interference and over-cut. By the finite element analysis with HyperWorks software, theshank structure had proved to be reasonable and reliable.4, Using UG/CAM on the Pelton runner cutting simulation to generate reasonableCNC machining tool paths; Based on the UG own post processor for two times thedevelopment, CNC machining tool paths can be applied to practical production of NCprogramming,and qualified products are got finally.