• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.53.5-53
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• 2001

In continuous galvanizing process at steel making plant, coating weight on the surface of strip that pass through air knife is controlled by the pressure at the chamber of air knife and the gap between the nozzle of air knife and strip. The pressure can be easily measured and controlled. But it is difficult to measure the distance between Air knife nozzle and strip, and also difficult to decide how much distance air knife move. Because, the gap between nozzle and strip varies with the height of air knife, intermesh of stabilizing roll and welding of strips that have different thickness. In this research, we developed a gap sensor that can measure the relative distance between Air knife nozzle and strip. And several tests are performed to find optimal condition for application at real plant. We performed test in which the possibility of the sensor to apply ...

• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1068-1073
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• 2010

용접 넥 플랜지는 파이프간의 상호연결에 널리 사용되고 있다. 이 플랜지는 열간 단조 공정으로 제작되며, 심해에서 고압이 요구되는 분야에 사용되는 경우 플랜지 기저부 및 목 부분에 높은 항복강도가 요구된다. 일반적으로 항복강도 향상을 위해 탄소함유량을 높이면 고 강도를 얻을 수 있으나, 용접이 요구되는 제품의 특성상 탄소함유량을 최대 0.47로 제한함으로써 고용체 강화에 의한 강도 향상에는 한계가 있다. 이러한 경우 탄소 함유량의 변화 없이 강도를 향상시킬 수 있는 결정립 미세화 강화를 이용하여 제품의 항복강도를 향상시킬 수 있다. 본 연구에서는 다구찌 기법을 통해 최적의 결정립 미세화를 위한 단조공정을 제시하고 타당성을 검토하기 위해 유한요소해석을 수행하였다.

• 한국안전학회지
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• 제29권6호
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• pp.28-33
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• 2014

Vibro ripper worked by high frequency vibration is developed to do rock fragmentation and work of ripper is the different concept with other existing breakers. The gear box-shank welded joint of vibro ripper is very important part to deliver vibromotive force to tooth, so this part should endure high frequency vibration environments. The purposes of this study are to choose the optimal welding conditions for fatigue strength. The conditions were made using three kind of shank materials and two kind of filler metals. Shank materials are Hadox-hituf, Posten80 and AR400, and filler metals are CSF-71T and CSF-81T. The fatigue test was conducted each condition. Fracture surface was observed to estimate fracture characteristics of welded joint using SEM.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.571-576
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• 1994

In recent years, ultrasonic has been widely applied in measurement and industrial fields and its application range has been expanded as a result of continuous research and development. Wire Bonding Machine, an instrument fabricating semi-conductor, makes use of ultrasonic bonding method. In order to improve the currently used wire bonding machine using ultrasonic energy, technical accumulation is needed steadily through development of exciting device of ultrasonic composed of piezoelectic vibrator and horn. This study investigates the design conditions affecting the dynamic characteristics through the theoretical and experimental analysis of piezoelectric vibrator and horn, The study conducts separately the system identification of piezoelectric vibrator in time domain and the modal analysis of horn in frequency domain. In theoretical model, the integrated modeling is conducted via a combination of dynamic identification of piezoelectric vibrator and theoretical analysis of horn. Hence comparison is made for theoretical and experimental results of the dynamic characteristics of the ultrasonic transducer composed of piezoelectric vibrator and horn. Form the results of this study we develop the design technique of ultrasonic transducer using dynamic characteristic analysis and propose the possibility of ultrasonic welding considering the optimal condition of the natural frequency and vibration mode of horn.

• 대한치과보철학회지
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• 제44권5호
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• pp.642-653
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• 2006

Purpose : The purpose of this study was to investigate the effect of the output energy(voltage) of laser welding on the strength and properties of joint of cast titanium(CP Gr II) and titanium alloy(Ti-6Al-4V). Material and method : Cast titanium and its alloy rods(ISO6871) were prepared and perpendicularly cut at the center of the rod. After the cut halves were fixed in a jig, and the joints welded with a laser-welding machine at several levels of output voltage of $200V{\sim}280V$. Uncut specimens served as the non-welded control specimens The pulse duration and pulse spot size employed in this study were 10ms and 1.0mm respectively. Tensile testing was conducted at a crosshead speed of 0.5mm/min. The ultimate tensile strength(MPa) was recorded, and the data (n=6) were statistically analyzed by one-way analysis of variance(ANOVA) and Scheffe's test at ${\alpha}$=0.05. The fracture surface of specimens investigated by scanning electron microscope (SEM). Vickers microhardness was measured under 500g load of 15seconds with the optimal condition of output voltage 280V. Results : The results of this study were obtained as follows, 1. When the pulse duration and spot size were fixed at 10ms and 1.0mm respectively, increasing the output energy(voltage) increased UTS values and penetration depth of laser welded to titanium and titanium alloy. 2. For the commercial titanium grade II, ultimate tensile strength(665.3MPa) of the specimens laser-welded at voltage of 280V were not statistically(p>0.05) different from the non-welded control specimens (680.2MPa). 3. For the titanium alloy(Ti-6Al-4V), ultimate tensile strength(988.3MPa) of the specimens laser-welded at voltage of 280V were statistically(p<0.05) different from the non-welded control specimens (665.0MPa). 4. The commercial titanium grade II and titanium alloy(Ti-6Al-4V) were Vickers microhardness values were increased in the fusion zone and there were no significant differences in base metal, heat-affected zone.

• 대한기계학회논문집A
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• 제40권12호
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• pp.1047-1053
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• 2016

본 연구에서는 최대 출력 6.3 kW의 연속 출력 파형 파이버 레이저를 사용하여 순 티타늄 용접을 실시하였다. 용접 시 티타늄은 산화 및 질화로 인한 취성영역을 형성하기 쉽기 때문에 적절한 실드가스를 사용하여 용접부를 대기로부터 보호해야한다. 따라서 최적의 실드가스를 선정하기 위하여 실드가스의 종류를 변화시켜 실험을 실시하였으며 그에 따른 용접성을 평가하였다. 비드색을 통하여 산화 및 질화정도를 간접적으로 판별하였으며 EDS와 EPMA를 사용하여 용접부의 성분분석을 실시하였다. 또한 광학 현미경 및 전자 주사 현미경으로 용접부의 미세조직을 관찰하였으며 경도측정을 통해 기계적 특성을 파악하였다. 용접부가 산화 또는 질화될 경우 회색 또는 노란색의 비드를 얻을 수 있었으며 비드표면뿐만 아니라 용접부 내부까지 산소 및 질소량이 증가하여 경도값이 모재 대비 3배 이상 크게 증가하였다. 결과적으로 아르곤 가스를 전면실드에 사용하였을 때 은백색의 건전한 비드를 얻을 수 있었다.

• 대한기계학회논문집
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• 제11권6호
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• pp.953-962
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• 1987

본 연구에서는 국산 구조용강의 SM 45C 와 SUS 304 재를 최고 강도치가 나타 나는 압접조건하에서 압접하여 우재료의 용착금속부, 열영향부, 각 모재부 소정의 장 소에 미소원공을 가공한 시험편을 토대로 피로크랙의 발생 및 전파거동을 응력 레벨의 고저를 고려하여 고찰하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제11권2호
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• pp.71-81
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• 1987

Nowadays, the high development of industrial technique demands the optimal design of marine structures to be welded under the water, because the underwater welding of the ship hull and marine structures can decrease manpower and cost of production. However there is not available at present any report on fatigue behavior about underwater welded joints. In this paper under tention- tension repeated fatigue stress with frequency of 10 cycles per second by local controlled system, the fatigue strength properties of underwater welded joints of SM41A-2 Plate-to-Plate of 10 mm thickness were experimentally examined. The results obtained were as follows : 1) The fatigue strength of underwater welded joints of SM41A-2 was peaked at the heat input of about 1, 400 joule/mm(180 A, 36 V), while, at the heat input of more than about 1, 100 joule/mm (160 A, 33 V) that of the underwater welds at the higher than cycle of life rather than the lower cycle was higher than that of the base metal but lower than that of the atmosphere welds on account of both cooling and notch effects. 2) The fatigue limit of underwater welds increased with an increase of heat input resulting in a peak of that at the heat input of about 1, 400 joule/mm and then decreased gradually. 3) The fatigue strength at N cycles was peaked between the heat input of about 1, 400 and 1, 700 joule/mm where the strain was rapidly increased. 4) It was confirmed that the optimal zone of heat input condition for obtaining the underwater welds fatigue strength higher than that of the base metal exists, and if out of this zone, the fatigue strength of the underwater welds was lower than that of the base metal because of lack weld penetration, inclusion of slag, voids, etc. 5) By the fatigue test, the underwater welds fractured brittly without visual deformation, so the strain was remarkably less than of the atmosphere welds. 6) The fatigue life factor was peaked at the heat input of about 1, 600 joule/mm (200 A, 36 V) at which the mean strain is a little higher than that of the base metal but quite lower than those of the atmosphere welds, resulting in good underwater welds because both fatigue strength and ductility of the underwater welds are higher than those of the base metal at such heat input.