The formation features of welded connections of aluminum alloys by combined laser radiation are considered. The
mechanism of a molten pool formation is investigated by numerical modeling and experimentally. The attainment
criteria of qualitative butt-welded connection are determined.
The laser systems with passive Q-switching by LiF:F2 crystals for precision technology are submitted. It is shown, that the application of laser system of the combined radiation allow to increase the processing productivity, and laser systems with the combined Q-switching-the processing quality.
The laser cutting of color metals and alloys by a thickness more than 2 mm has significant difficulties due to high reflective ability and large thermal conduction. We made it possible to raise energy efficiency and quality of laser cutting by using a laser processing system (LPS) consisting both of the YAG:Nd laser with passive Q-switching on base of LiF:F2- crystals and the CO2 laser. A distinctive feature of the LPS is that the radiation of different lasers incorporated in a coaxial beam has simultaneously high level of peak power (more than 400 kW in a TEM00 mode) and significant level of average power (up to 800 W in a TEM01 mode of the CO2 laser). The application of combined radiation for cutting of an aluminum alloy of D16 type made it possible to decrease the cutting energy threshold in 1.7 times, to increase depth of treatment from 2 up to 4 mm, and velocity from 0.015 up to 0.7 m/min, and also to eliminate application of absorptive coatings. At cutting of steels the velocity of treatment was doubled, and also an oxygen flow was eliminated from the technological process and replaced by the air. The obtained raise of energy efficiency and quality of cutting is explained by an essential size reducing of a formed penetration channel and by the shifting of a thermal cutting mode from melting to evaporation. The evaluation of interaction efficiency of a combined radiation was produced on the basis of non-stationary thermal-hydrodynamic model of a heating source moving as in the cutting direction, and also into the depth of material.
The threshold modes of metal cutting by combined radiation of CO2 laser with a ring TEM01 mode, 800 W power, 200 microns beam diameter and pulse-periodic Nd:YAG laser with a TEM00 mode, 90 microns beam diameter, 80 W average power are investigated. It was established, that improvement of CO2 laser radiation usage efficiency and narrowing of the cutting channel to Nd:YAG laser spot diameter is caused by tightening of radiation into the narrow channel.
Are known powerful technological YAG:Nd-lasers with passive Q-switching on a LiF:F2- crystal. At use of the unstable resonator with a convex mirror was received single- mode pulse-periodic radiation with high spatial brightness, small divergence and large coherent length. The phase conjugation of technological Nd-lasers on the dynamic hologram in a LiF:F2- crystal has allowed to increase efficiency of laser processing. In the present work the modes of generation and technological opportunities of YAG:Nd-lasers and on Nd-glass c by adaptive resonators on a basis of Sagnac interferometer (SI) are investigated at pulse-periodic pumping. Phase conjugation and passive Q- switching were carried out simultaneously with the help of a LiF:F2- crystal, placed in SI. Crystal transparency linearly changes on length, therefore by moving of a crystal normally to an optical axis it is possible over a wide range to operate power and temporary parameters of laser radiation. High power and spatial parameters of radiation, as the opportunity of their control, directly during processing by crystal moving, have allowed effectively to carry out the calibrated drilling in various materials by a diameter 50 - 400 micrometers and depth up to 20 mm. For increase of efficiency of fragile materials destruction the combination of spatial and temporary modulation of laser radiation was used. The formation in a volume or on the material's surface of alternating areas with high gradients of thermally induced pressure has allowed to decrease the destruction's power threshold in some times. Besides by optimization of spatial parameters it is possible to improve quality of laser processing by decreasing thermally induced pressure and deformations.
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