Improving quality of laser material processing by spatial and temporal modulation of laser power
| Autor: | Chih-Hsiang Yang, 楊智翔 |
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| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 Scanning along the contour of the workpiece with a Gaussian power distribution CO2 laser will lead to a Gaussian distribution of energy absorption which results in the cutting edge being not sharp. In addition, laser scanning during the accelerating, decelerating or turning around a corner, the various speed leads to the variation of the irradiation time, the absorbed energy in the low-speed portion is too high while the absorbed energy in the high-speed portion is too low. The aim of this study is to improve the quality of laser material processing by spatial and temporal modulation of laser power. Spatial modulation was that using a beam shaper, which transfers the Gaussian distribution of the laser beam shape to the hat-top shape distribution, and a focusing lens to obtain a smaller light spot in the imaging point. The power distribution of the light spot was uniform. The equal energy absorbed in the irradiation area led to a sharp cutting edge. Temporal modulation was that using a CO2 laser with a power feedback control system, and an acousto-optic modulator for adjusting the laser power in accordance with the speed of the workpiece. The faster the workpiece speed is, the higher the laser power is, and vice versa. Consequently, the energy absorbed in the low-speed region and in the high-speed region can be equal. Finally, a scanning on parts and then a microscopic investigation to verify the quality improvement using above technology were conducted. This technology can be applied to laser drilling, cutting, welding, and other laser material processing. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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