In the fiber laser cutting of steel with nitrogen assist gas, the effect of positional relationship between the centers of a nozzle and a laser beam on the cutting quality was investigated by laser cutting experiments and computational fluid dynamics analysis of the assist gas flow. The laser cutting experiment of 3.2 mm cold rolled steel was carried out by a 3 kW fiber laser. The spot diameter of the laser beam and the inner diameter of the nozzle were 140 μm and 2.0 mm, respectively. In laser cutting, by shifting the center of the laser beam toward the cutting direction inside the nozzle, the dross height becomes large. In the nozzle shifting setup, the cooling effect becomes high due to a large inflow of assist gas into the kerf, and the reduction of assist gas pressure results in the control of the cooling effect. The formation of appropriate kerf shape by changing the focusing position inside the workpiece leads to an appropriate flow field of assist gas in the kerf. As a result, similar dross height could be obtained by the nozzle shifting setup, compared with that by the coaxial setting of the nozzle and laser beam. The nozzle shifting setup can perform the equivalent dross height to the coaxial setting of the laser beam and nozzle even at lower pressure of the assist gas, and the reduction of assist gas consumption is possible at the same level of dross height in fiber laser cutting of steel.

中文翻译：

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通过移动喷嘴轴减少钢纤维激光切割中的锡渣的基础研究

在用氮气辅助气体对钢进行纤维激光切割时，通过激光切割实验和辅助气体流动的计算流体动力学分析，研究了喷嘴中心和激光束之间的位置关系对切割质量的影响。通过3 kW光纤激光器对3.2 mm冷轧钢进行了激光切割实验。激光束的光斑直径和喷嘴的内径为 140μ分别为m和2.0 mm。在激光切割中，通过使激光束的中心朝向喷嘴内的切割方向移动，浮渣高度变大。在喷嘴移位设置中，由于辅助气体大量流入切缝中，冷却效果变高，并且辅助气体压力的降低导致了冷却效果的控制。通过改变工件内部的聚焦位置来形成适当的切口形状，导致在切口中产生适当的辅助气体流场。结果，与通过喷嘴和激光束的同轴设置相比，通过喷嘴移动设置可以获得类似的浮渣高度。即使在辅助气体压力较低的情况下，喷嘴移动装置也可以执行与激光束和喷嘴同轴设置相同的浮渣高度，