서지주요정보
레이저 미세용접에서 시각센서를 이용한 용접선 추적 및 용융풀 모니터링에 관한 연구 = A study on the seam tracking and weld pool monitoring in laser microwelding by using a vision sensor
서명 / 저자 레이저 미세용접에서 시각센서를 이용한 용접선 추적 및 용융풀 모니터링에 관한 연구 = A study on the seam tracking and weld pool monitoring in laser microwelding by using a vision sensor / 이승기.
저자명 이승기 ; Lee, Seung-Key
발행사항 [대전 : 한국과학기술원, 2003].
Online Access 원문보기 원문인쇄

소장정보

등록번호

8014307

소장위치/청구기호

학술문화관(문화관) 보존서고

DME 03030

SMS전송

도서상태

이용가능

대출가능

반납예정일

초록정보

Vision sensors adopted for automatic seam tracking in fusion welding are generally based on optical triangulation. They basically have an auxiliary light source and preview distance - the distance between welding and sensing position. It can generate some tracking error in automatic seam tracking, especially in micro welding of small parts. On the other hand, vision systems adopted for the weld pool monitoring are generally equipped with a high-speed camera and intense illumination. In this study, a vision sensor was applied to find the weld seam by monitoring the weld pool in pulsed Nd:YAG laser welding. The vision sensor with a 810nm bandpass filter and 1/30000 shutter speed observed the weld pool and the weld seam was extracted from the image of monitored weld pool. No auxiliary illuminating light source was used for monitoring the weld pool. Pulsed Nd:YAG laser welding is characterized by the interaction of multiple laser pulses, while the shape and brightness of the weld pool change temporally even in one pulse duration. Therefore, the shutter of the CCD camera was synchronized with the start of each pulse, and opened with a specific time delay from the laser pulse start. Experiments were carried out to find the appropriate moment of shutter triggering for relatively clear images. The principle of seam tracking using the developed vision sensor is based on the separation angle between the vision sensor and Nd:YAG laser focusing optics to find the 3D information of weld pool centerline. The CCD camera and Nd:YAG laser beam, instead of the laser diode plane as in the generally used vision sensor, have a separation angle and the weld pool is imaged in CCD. As a result, the cross-section of Nd:YAG laser beam in a developed vision sensor can be regarded as the plane of laser diode in other vision sensors using a structured light. Consequently the weld pool centerline, where the cross-section of laser beam intersects the weld pool, is acting as the laser stripe on workpiece. Weld pool image contains the information about the weld penetration. The information about a penetration can be extracted from the geometry and brightness of weld pool. Weld pool parameters that represent the characteristics of the weld pool image were selected based on the geometrical appearance and brightness profile. In order to achieve accurate prediction of the weld penetration, which is non-linear model, neural network with the selected weld pool parameters was applied. The tests for the proposed monitoring and prediction method were performed to the various weld conditions and workpiece conditions. As a result of the test, the proposed parameters including the information from the brightness profile resulted in the improvement of prediction because of the more accurate description of the weld pool image. Finally, penetration control was successfully performed to the workpiece of continuous width change. As a specific target, the previous penetration prediction and control test were applied to 200 μm edge joint.

서지기타정보

서지기타정보
청구기호 {DME 03030
형태사항 x, 155 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Seung-Key Lee
지도교수의 한글표기 : 나석주
지도교수의 영문표기 : Suck-Joo Na
수록잡지명 : "A study on automatic seam tracking in pulsed laser edge welding by using a vision sensor without auxiliary light source". Journal of manufacturing systems
학위논문 학위논문(박사) - 한국과학기술원 : 기계공학전공,
서지주기 참고문헌 : p. 148-155
주제 시각센서
레이저 미세용접
용접선 추적
용융풀 모니터링
용입 예측 및 제어
vision sensor
laser microwelding
seam tracking
weld pool monitoring
penetration prediction and control
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