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노경보(Kyoung-Bo Ro),유영태(Young-Tae Yoo),오용석(Yong-Seak Oh),신호준(Ho-Jun Shin),김지환(Ji-Hwan Kim) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
The Nd: YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. In spite of its good mechanical application due to the poor welding properties. The major process parameters studied in the present laser welding experiment were position of focus, travel speed and laser power.
SM45C와 SUS304의 Nd:YAG 레이저 맞대기용접특성
오용석(Yong-Seok Oh),유영태(Young-Tae Yoo),노경보(Kyoung-Bo Ro),신호준(Ho-Jun Shin),김지환(Ji-Hwan Kim) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
Welding characteristics of austienite 304 stainless steel and SM45C using a continuous wave Nd: YAG laser are experimentally investigated. Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. This paper describes the weld ability of SM45C carbon steel and austienite 304 stainless steel for machine structural use by Nd: YAG laser.
신호준(Ho-Jun Shin),유영태(Yong-Tae Yoo),오용석(Yong-Seak Oh),노경보(Kyoung-Bo Ro) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Laser heat treatment is an affetive technique used to impreve the triboperies and also to increase the servise life of automobile components such camshafts, crankshatfs. lorry brake drums and gears. High power CO2 lasers and Nd:YAG lasers are employed for hardening of materls and hence are of potentoal appliication in the autombile industries, The heat is conducted rapidiy into bulk of the specimen causing self-quenching to oeeur and the formation of matrensitic struture. In this in vestigtion, the mierostructrual features occurring in Md:YAG laser hardening SM45C and STD? steel are discussed with the use of optical mieroseopic and seanning electrom moerosepic analysis Moreover This peper deseribes optimisation of the processing parameters for maxmum hardened depth of SM45C and STD steel specimens of 10mm theckness by using CW Nd:YAG laser.
레이저 열처리 광학계를 이용한 금형소재의 표면 열처리 특성
신호준(Ho-Jun Shin),유영태(Young-Tae Yoo),신병헌(Hyung-Heon Shin),노경보(Kyoung-Bo Ro) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Laser surface treatment technologies have been used to improve characteristics of wear and to enhance the fatigue resistance for mold parts. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with a uniform hardness. The objective of this research work is to investigate the influence of the process parameters, such as power of laser and defocused spot position, on the characteristics of laser surface treatment for the case of SKD61 steel and SCM4 steel. From the results of the experiments, it has been shown that the maximum average hardness is approximatly 700~780 Hv when the power, focal position and the travel of laser are 1,095 W, 0㎜ and 0.3 m/min, respectively. In samples treated with lower scanning speeds, some small carbide particles appear in the interdendritic regions. This region contains fine martensite and carbide in proportions which depend on the local thermal cycle.
연속파형 Nd:YAG 레이저를 이용한 SM45C 용접특성
유영태,노경보,오용석 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.2
The Nd:YAG laser in combination with the optical fiber increase the automation and the flexibility of a whole industry. The Nd:YAG laser welding process in one of the most advanced manufacturing technologies owing to its high speed and penetration. This paper describes the weldability of SM45C carbon steel for machine structural use by Nd:YAG laser. Major process parameters were position of focus, travel speed and laser power. The results showed that peneration depth of the weld was increased with increasing applied laser power. Microstructural examinations and calculations and indicated that the microstructure of the laser weld, which experienced very high heating and cooling cycle during welding process. The results of this study provide application possibility of Nd:YAG laser welding for SM45C carbon steel
연속파형 Nd:YAG SM45C 레이저 용접의 결함 감소연구
유영태,오용석,노경보,신호준 朝鮮大學校 機械技術硏究所 2003 機械技術硏究 Vol.6 No.1
본 연구에서는 Nd:YAG 연속파형 레이저를 이용하여 레이저 용접시 레이저빔의 출력에 대한 레이저범의 이송속도를 변화시켜 심입용접을 실시했다. 열처리를 하지 않고 용접을 실시했을 경우 매우 조대한 기공이 많이 발생하였지만 열처리 후 용접을 실시했을 때는 몇몇 미세한 기공만 발생하였다. Present investigation reports on the effect of incorporating pre-heating on the mechanical properties of laser weldi'ng joints. The Nd:YAG laser in combination with the optical fiber increase the automation and the flexibility of a whole industry. The Nd:YAG laser welding process is one of the most advenced menufacturing technologies owing to its high sped and penetration. This paper describes the weldability of Sh4456 carbon steel fox machine structural use by Nd:YAG laser. Optical microscopy SEM were performed to observe the micro structures and to determine the structures of welded zone. In addtion, mechanical propreties, were measured by tensile test to evaluate the formablity of the welded specimen. The results show that proper selection of the control parameters for per-heating technique can result the porosity and cracking of the welding significantly, and improve the welded joints mechanical properties, such as higher tensile strength and better durability.