Coordinate Measuring Theory And Software Development Of Pine-Tree Milling Cutter

The pine-tree milling cutter currently products the turbine rotor wheel slot,which has the same structure as pine-tree in the turbine industry. The precision of pine-tree milling cutter has large influence on the slot accuracy level , so pine-tree milling cutter is necessary to be measured. It is usually measured with automatic imagers, which are expensive. The thesis aims at developing a special measurement software for pine-tree milling cutter on CMM to achieve the measurement. The main works are as follows.(1)The profile deviation of pine-tree milling cutter was established as the measurement project after analysing the characteristics of structure. The theoretic coordinates of sampled points were calculated using equal-spaced method, when the mathematical model of blade profile was established. And the assessed algorithm of profile deviation was designed through the conversion between 2-D coordinates and 3-D coordinates.(2)Designed some key techniques on how to measure pine-tree milling cutter on CMM, including the probe angle algorithm, the motion strategy of controlling probe, the normal vector algorithm of measured points and how to set the best number of points.(3)The measurement software was developed with modular design by VB based on CMM, and realized contact-measurement to pine-tree milling cutter. Main function of the software included parameter inputting, data processing, results saving, and inspection report printing.(4)Analyzed the measurement uncertainty and calculated standard uncertainty coming from data processing,standard error, rail lines error, rail vertical error, thermal deformation error and probe error. Then, the expanded uncertainty was synthesized and the repeatability was experimented.All the results indicated that the measurement principles developed in this paper were correct, and the techniques could measurement all types of pine-tree milling cutters reliably.