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Reduction of Radius of Curvature in Thin-Sheet-Metal Bending by Ultrashort-Pulsed Laser Peen Forming
摘要： Ultrashort-pulsed laser peen forming is a method of thin-sheet-metal forming using laser-induced shock waves. The authors have applied the process to microsheet parts bending, which is accomplished by repeating line scanning. However, when a severe curvature is requested, nonnegligible reduction of sheet thickness is induced by laser ablation. In order to restrict the thickness reduction, the authors attempted to improve the bending efficiency, which would allow a reduction in the number of necessary pulses. Scanning velocity and scanning pitch were changed, while the total irradiated pulse number was constant. The obtained results showed that a scanning velocity higher than the conventional one is favorable for improving the bending efficiency. In addition, smaller scanning pitches were adopted to reduce the radius of curvature. The influence of the scanning pitch on the bending efficiency was much weaker than that of scanning velocity. From the results of the evaluation of efficiency and scanned surface asperity, a scanning velocity of 20 mm·s-1 was judged to be the best. The best scanning condition achieved a 40% smaller radius of curvature than the conventional one.
关键词： bending,bending efficiency,laser-induced shock wave,ultrashort-pulsed laser,incremental forming,scanning velocity,forming property,laser peen forming
更新于2025-09-23 15:21:01
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Efficiency improvement of thin-sheet-metal bending by femtosecond laser peen forming
摘要： Femtosecond laser peen forming is die-less incremental sheet forming using laser induced shock waves. It was applied to bending of thin sheet micro parts. When severe curvatures are requested, the process needs dense laser pulse irradiation, which reduces sheet thickness remarkably owing to excessive laser ablation. High bending efficiency per pulse is necessary to realize a small radius of curvature without sheet thickness reduction. The authors attempted to improve the bending efficiency by changing scanning velocity and scanning pitch. Optimized scanning achieved 40% smaller radius of curvature than conventional one, in spite of same irradiated pulse density. Obtained knowledge is effective in miniaturization and productivity increase.
关键词： Femtosecond laser,Bending,Thin-sheet-metal,Laser peen forming,Bending efficiency,Laser induced shock wave,Micro parts
更新于2025-09-12 10:27:22
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Ultra‐High Fidelity Laser‐Induced Air Shock from Energetic Materials
摘要： Recent interest in the implementation of the Laser-induced Air Shock from Energetic Materials (LASEM) technique prompted an investigation using ultra-high-speed imaging diagnostics to provide early-time (sub-μs) shock-wave-radius-versus-time data necessary to accurately determine the characteristic laser-induced-shock velocity (y-intercept) for high explosives (HE) of interest. Ultra-high-speed focused-shadowgraphy images were collected from nanosecond-pulsed laser-ablated samples of HE similar to those in the published literature. Shadowgraphy images were collected using interframe times ranging from 50–750 ns, with exposure times of 5 ns. Acquired shock-wave-radius-versus-time data permitted a high-fidelity assessment of the shock wave velocity produced at the characteristic radius of the generated laser-plasma pulse. The resulting data from eight different HE indicated that early-time energy contributions and the resulting laser-induced shock velocity profiles produced from ablation of the HE material were indistinguishable amongst the explosives tested for the majority of the time domain characterized (0–12 μs).
关键词： laser-induced shock wave,shock physics,energetic-material characterization,detonation performance,laser-induced plasma
更新于2025-09-11 14:15:04