| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 88 === Abstract
Based on the regenerative trajectory grinding theory, both the hydraulic and the pneumatic surface grinding systems are developed in this thesis. Both systems grind precisely any part of arbitrary surfaces automatically. The generative grinding systems have the advantage of not being affected by the precision of the attached CNC machine structure. Therefore, they can be used to polish a mold surface with the precision higher than that of the attached CNC machine .
In this paper, we accomplished several key tasks including (1) 3D mold surface scanning, (2) 3D surface reconstruction, (3) trajectory planning for reconstructive surfaces (4) characterization of the best working range of key grinding parameters based upon numerical simulation, (5) experimental design for minimum experimental runs under a given resolution, and (6) comparative study between both the hydraulic and the pneumatic surface grinding systems. The process parameters thus obtained are used to construct the pneumatic self-adjusted constant-pressure grinding device. Finally, the performance of the hydraulic and the pneumatic grinding systems are evaluated. The study also characterize important system parameters and process factors that affect the resulting quality of mold surfaces. The size of the abrasives is also shown to be crucial. Although both of the hydraulic and the pneumatic grinding systems can achieve high surface quality at the level of micrometer, the efficiency that is given by the pneumatics based system (Ra= 0.023 mm) turns out to be better than that of the hydraulic system (Ra= 0.090 mm). This is mainly attributed to the soft grinding head and the constant pneumatic pressure, particularly design for this project.
Two sets of precision free surface grinding systems are presented and experiments are conducted to verify the results. In order to make the system suitable for automation, several major tasks are accomplished. These tasks include (1) surface scanning and reconstruction, (2) mathematical modeling of grinding trajectory on mold surfaces, (3) analysis of optimal parameter ranges for surface grinding, (4) experimental design of the hydraulic and the pneumatic grinding systems, and (5) performance evaluation of both grinding systems. The experimental results indicate that both systems are able to work for various mold surfaces.
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