한국해양대학교

Detailed Information

Metadata Downloads

레이저 용접현상의 유동가시화에 의한 고찰

DC Field Value Language
dc.contributor.author 태경봉 -
dc.date.accessioned 2017-02-22T06:01:51Z -
dc.date.available 2017-02-22T06:01:51Z -
dc.date.issued 2007 -
dc.date.submitted 56850-02-09 -
dc.identifier.uri http://kmou.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002174866 ko_KR
dc.identifier.uri http://repository.kmou.ac.kr/handle/2014.oak/8979 -
dc.description.abstract The main purpose of this study was to achieve optimum bead welding conditions when weld the STS304 stainless steel sheet with the pulse- Nd:YAG laser. The conducting characteristics of plasma/plume using the schlieren system and a high speed camera -a flow visualization technique- were observed and analyzed. The laser output characteristics of the STS304 stainless steel sheet were investigated from multiple viewpoints as follows: 1) the relation of laser output energy and peak power on pulse width, 2) the relation of laser output energy and peak power on lamp voltage, 3) the relation of welding bead width and penetration depth on defocused distance. Afterwards, the effects of the shield gases while laser welding under actual conditions were closely analyzed: in air, static, and dynamic shield gas atmosphere. In air, the occurrence of many spatters was observed, even in the low-end laser output condition. But, in a shield gas atmosphere, the spatters rarely occurred, even in the high-end laser output condition, and the plasma stabilized quickly. The laser outputs in a static shield gas atmosphere, were measured under three voltages (243V, 250V, 280V) -
dc.description.abstract the occurrences under actual conditions of the plasma/plume were compared and analyzed. Measuring for various types of shield gas atmospheres (nitrogen, argon, and helium) revealed a gradual weakening in plasma intensity from argon to nitrogen to helium. The plasma volume gradually decreased, and the gas flow was virtually undetectable in the helium shield gas atmosphere. Afterwards, the occurrences of spatter and plasma phenomena with nozzle diameters of 2, 4, 6, 8, and 10 mm, at the distances of 13, 16, 19, and 21 mm from the end of nozzle to the welding point, at nozzle angles of 0, 20, 40, and 60 degrees, and shield gas flow-rates of 5, 15, and 25 liters/min were observed and analyzed. The optimum laser welding condition, using a nozzle in a dynamic shield gas atmosphere, was determined by the nozzle diameter, the distance from the nozzle end to the welding point, the nozzle angle, and the flow rate of the shield gas. Using the STS304 stainless steel sheet as a test material, the optimum bead welding condition with the pulse-Nd:YAG laser was confirmed to be a nozzle diameter of 6 mm, at the distance of 13 mm from the nozzle end to the welding point, at a nozzle angle of 40 degrees, and at a shield gas flow-rate of 25 liters/min. -
dc.description.tableofcontents 1. 서론 = 1 1.1 연구 배경 및 목적 = 1 1.2 연구내용 = 2 2. 이론적 배경 = 4 2.1 유동가시화기법의 종류와 원리 = 4 2.2 Nd:YAG 레이저의 발진원리와 특성 = 25 2.2.1 Nd:YAG 레이저의 발진원리 = 25 2.2.2 Nd:YAG 레이저의 특성 = 33 2.3 실드가스의 종류와 특성 = 39 2.3.1 실드가스의 종류 = 39 2.3.2 실드가스의 특성 = 40 3. 실험 장치 및 방법 = 45 3.1 실험 재료와 장치 = 45 3.1.1 실험재료 = 45 3.1.2 펄스 Nd:YAG 레이저 용접장치 = 49 3.1.3 고속도카메라 및 슈리렌 시스템 = 53 3.2 실험방법 = 57 3.2.1 레이저빔의 비드 점용접 방법 = 57 3.2.2 정적 및 동적 실드가스 분위기에서의 용접방법 = 59 3.2.3 슈리렌 시스템을 이용한 용접현상의 관찰방법 = 63 4. 실험결과 및 고찰 = 65 4.1 레이저빔의 출력특성 = 65 4.1.1 펄스폭에 따른 레이저 출력특성 = 65 4.1.2 인가전압 변화에 따른 레이저 출력특성 = 67 4.2 레이저빔의 용접특성 = 69 4.2.1 집광 광학계의 비초점거리에 따른 용접특성 = 69 4.2.2 레이저 출력에 따른 용접특성 = 71 4.2.3 대기 및 정적 실드가스 분위기에서의 용접특성 = 74 4.3 정적 실드가스 분위기 변화에 따른 레이저용접 현상 = 84 4.3.1 각종 실드가스 분위기에서의 레이저 유기플라즈마의 거동 = 84 4.3.2 각종 실드가스와 레이저 출력변화에 따른 용접현상 = 89 4.3.3 정적 실드가스에 의한 스패터 발생 = 101 4.4 동적 실드가스 분위기에서의 레이저용접 현상 = 109 4.4.1 실드가스 노즐의 직경에 따른 레이저용접 현상 = 110 4.4.2 실드가스 유량변화에 따른 레이저용접 현상 = 115 4.4.3 실드가스 거리에 따른 레이저용접 현상 = 119 4.4.4 실드가스 분사각도에 따른 레이저용접 현상 = 123 4.4.5 실드가스 종류에 따른 레이저용접 현상 = 129 5. 결론 = 133 참고문헌 = 135 -
dc.language kor -
dc.publisher 한국해양대학교 해사산업대학원 -
dc.title 레이저 용접현상의 유동가시화에 의한 고찰 -
dc.title.alternative Consideration by Flow Visualization of Laser Welding Phenomenon -
dc.type Thesis -
dc.date.awarded 2007-02 -
dc.contributor.alternativeName Tae -
dc.contributor.alternativeName Gyung-Bong -
Appears in Collections:
기관시스템공학과 > Thesis
Files in This Item:
000002174866.pdf Download

Items in Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse