Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
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Study of Characteristics of Assist Gas in Laser Machining Using Flow Visualization Techniques

유동가시화 기법을 이용한 레이저가공의 보조가스 충돌특성에 관한 연구

  • Son, Sang-Hyuk (Dept. of Mechanical and Aerospace Engineering, Korea Aerospace Univ.) ;
  • Lee, Yeol (Dept. of Mechanical and Aerospace Engineering, Korea Aerospace Univ.) ;
  • Min, Seong-Kyu (Dept. of Mechanical and Aerospace Engineering, Korea Aerospace Univ.)
  • 손상혁 (한국항공대학교 항공우주 및 기계공학과) ;
  • 이열 (한국항공대학교 항공우주 및 기계공학과) ;
  • 민성규 (한국항공대학교 항공우주 및 기계공학과)
  • Received : 2010.06.29
  • Accepted : 2010.11.23
  • Published : 2011.02.01
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Abstract

The characteristics of supersonic coaxial/off-axis jet impingements on a slanted kerf surface were experimentally studied, to investigate the role of the assist gas that removes molten materials from cut zone formed by laser machining. In this parametric study, hundreds of high-resolution schlieren images were obtained for various gas pressures, distances between nozzle exit and kerf surface, kerf widths, and alignments of off-axis nozzle. It was noticed that simply increasing the assist gas pressure was not effective in eliminating the flow separation that occurs downstream of the kerf surface. However, it was also observed that by increasing the kerf width and utilizing off-axis nozzles, the separation of the assist gas on the kerf surface can be weakened. The effect of the distance between the nozzle exit and the kerf surface on the characteristics of separation occurring on the kerf surface was found to be lower in the case of supersonic nozzles than that in the case of sonic nozzles.

레이저가공에서 가공부위의 용융물질을 제거하는 보조가스의 역할을 살펴보기 위하여, 절단경사면에 충돌하는 초음속 동축/탈축노즐 유동의 특성이 실험적으로 관찰되었다. 보조가스의 압력, 노즐과 절단면과의 사이거리, 절단폭, 그리고 탈축노즐의 위치 등 다양한 관계변수의 변화에 대하여, 수백 개의 고해상도의 쉴러린 영상이 획득되었다. 그 결과, 단순한 보조가스의 증가가 절단면 하부에서 발생하는 유동박리를 제거하는데 효율적이지 않음이 관찰되었고, 절단폭의 증가와 탈축노즐의 운용으로 절단면에서의 박리현상을 경감시킬 수 있음이 확인되었다. 또한 음속노즐에 비하여 초음속노즐의 경우는 노즐출구와 가공면 사이의 사이거리가 절단면에서의 박리현상에 큰 영향을 미치지 않음이 관찰되었다.

Keywords

References

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