전기용접의 효율적인 실기지도 방법에 관한 연구 : 맞대기이음의 결함요인 분석을 중심으로

박재순 삼척대학교 산업대학원 2004 국내석사

우리나라는 5차에 걸친 경제개발이 성공적으로 수행되어 공업입국으로 중화학공업이 육성되었고 금속 및 기계공업은 최근에 와서 급격히 발전하였으며 특히, 용접접합은 공업의 발전에 대단히 중요한 역할을 하고 있는 효율적이고 신뢰성이 있는 경제적인 기계 가공법이다. 용접기술은 기계 제품의 생산과 수리의 주된 수단중의 하나로서 크고 작은 공장에서 널리 사용되고 있고 그 적용범위도 매우 넓어 선박, 항공기, 차량, 공작기계, 압력용기, 탱크, 교량, 건축물, 해양구조물 등의 공업 전 분야에 중요한 가공법이며 현대 과학의 첨단을 걷고 있는 원자로, 급속도로 발전하는 우주개발 공업도 새로운 용접기술의 개발에 의하여 가능하게 된 바와 같이 현재의 산업계 각 분야에서의 기술혁신과 제품 개발의 진행과 더불어 용접기술도 각 방면에 많은 진보가 이루어지고 있으며 이에 따라 맞대기 용접의 기술도 다양하고 심도가 깊어 졌으며 많은 기술적인 문제 또한 안고 있다. 공업계 고등학교 기계과 실습시간에 용접에 관하여 효율적으로 실기지도를 하여 실제적인 용접문제를 해결하고 국가기술 자격증 시험에 많이 합격할 수 있도록 하며 용접기술의 향상을 도모하여 현장에서의 기술을 향상시키는 것이 본 연구를 하게된 목적이며 다음과 같은 결론을 얻게 되었다. (1) 효율적인 실기 지도에서 ① 년 간 실습요소 분석표를 만들어 실습계획을 하였더니 실기지도 과정을 정립하였음. ② 과제별 기초기능단계, 전문기능단계, 평가기능단계, 현장응용 단계로 구분하여 지도하였더니 흥미유발과 기초기능을 심화시킬 수 있었으며 실기평가에서와 같은 결론을 얻었다. ③ 용접의 기본이 맞대기 용접으로부터 응용된다는 핵심을 알고 평가코스에서 60점이상 합격권이 30명으로 국가기술 자격증 실기시험에서 100% 합격을 하였음. (2) 평가 기준의 다양화에서 ① 평가 기준의 다양화로 용접기능의 향상을 가져왔으며 동시에 실기점수가 높아졌고, 기술자격검정 시험에서 100% 합격률을 나타냈음. ② 요소별 평가로 기능이 현저하게 향상되었으며 합리적인 개인 실기평가표 배점으로 기능인으로서의 자질이 향상되어 자기 도약에 큰 영향을 주었다. ③ 위와 같은 다양하고 객관성 있는 평가에 학생들이 실습에 임하는 의욕이 진작되었고 지도교사의 지도방법이 현저하게 이루어짐으로 교수-학습에 능률적이고 기능의 신장을 높힐 수 있었다. Now 5―year plans of economic development 5times in succession have successfully been accomplished for welfare society through industry oriented policy, specially the heavy chemical industry, and metal machinery industry has rapidly grown and, welding industry may well be called an efficient & economical method for development of basic industry. Welding technology, as one of the main ways for production & repairment of machinery, is widely used in factories, large or small, and as the range of its use is very wide, it is used for ship, airplane, vehicle, factory machinery, industrial equipment, press, tank, bridge, construction structure as well as for atomic reactor, space business. Welding technology has been developed with industrial technology innovation & development of products in various fields. Rod-welding, one of the welding technologies, is widely & deeply applied and keeps a lot of problems, too. I wrote this report for the following purposes ; 1. To solve the practical problems happened in Engineering high school. 2. To help for youngsters to take welding licence of national qualification examination. 3. To develop better skills through on the job training course. I suggest to you the following conclusion through my experiments. (1) The leading in efficient practice a) I made a year-plan for practice(table 17) with analysis plan of practicing factors.(table 16) b) As I thought them with a plan of a few steps like basic function, professional function, evaluation function & practical application, I found that interest inducement & basic function were deepened, and the evaluation for practicing technology was found very good as table 19. c) Most of students understood that the basic of welding, starts from rod-welding, which helped them to pass the national qualification examinotion for welder without any failure.(table 20) (2) Diversification in evaluation standard. a) The diversification of evaluation standard of welding has increased the welding technology as well as students grade point, and the appliciants passed the national qualification examinotion 100 percent. b) The students function has significantly increased by evaluation of factors, and thanks to rational evaluation of practicing test,(table 21) the quality of technician has increased, which helped greatly the student's self-training. c) The above simple & rational system of evaluation stimulated the students to practicipate positively in practice, and the method of leading teachers has greatly been bettered with efficient way of lesson & study, which expanded the function of welding.

설문조사를 통한 전기용접 근로자의 안전사고 유형분석 및 원인 고찰

김재기 東國大學校 産業技術環境大學院 1998 국내석사

The purpose of this study was, accordingly, to serve as a basis for safety measure planning and for the improvement of all sorts of problems, including potential dangerous factors in the process of electric welding, by examining the way of thinking about industrial disaster and the need of safety, and by grasping the substance of disaster and what problems there were. First, as a result of investigating the disasters occurred during electric welding process, it's found that the most dangerous spot for electric welding disaster was a moist place. The most frequent accident pattern was an electric shock, and the physical part that was most vulnerable to an electric shock was hand, followed by head and foot in the order named. Among electric welding equipments, the most dangerous one was an electric welding holder, and the next was an electric welding machine, a cable and an electric rod in the order named. The electric disaster appeared to be caused mainly by welder's unsafe behavior. An electric shock disaster in welding is caused most often by an electric welding holder, and the Bakelite that exists around an electric conductor must be made up of new material. In particular, an automatic electric shock-proof machine must be installed without exception, and there is a need to manage a working environment carefully, including ventilation facilities, by having welders wear a protective helmet approved by the authorities concerned, and so on.

기계구조용 탄소강관의 전기저항용접에 관한 연구

이현진 晋州産業大學校 産業大學院 2008 국내석사

Several electric resistance welding (ERW) processes are available for tube and pipe production. ERW is created by applying a combination of heat and pressure, or forging force, to the weld zone. A successful forged weld uses the optimum amount of heat, which is normally slightly less than the melting point of the material, and a nearly simultaneous application of circumferential pressure to the section, which forces the heated edges together In this thesis, we discribed main examples and factors of the welding defect in ERW process of pipe production and suggested the optimum welding condition of STKM11A and 16A welding material through nonmetallic containment test, metallic structure test, the state and defect analysis of welding surface etc.

첨단고강도강 전기저항점용접부의 비산현상과 인장성질에 미치는 합금원소의 영향

공종판 부산대학교 대학원 2015 국내박사

-Effect of Alloying Elements on Expulsion in RSW of AHSS- This study examined the effects of alloying elements, such as Cr, Si, Al, C and Mn, which are normally used to modify the composition of advanced high strength steels(AHSS), on the expulsion phenomenon during electric resistance spot welding(RSW) as well as the effects of alloying elements on the expulsion limit current (CExp.). Anequation for the CExp. prediction was derived from the correlation between the CExp. and alloying element: CExp. (kA) = 9.85 – 0.74Si – 0.67Al – 0.28C – 0.20Mn – 0.18Cr. The coefficient of determination between the calculated and measured values was sufficiently high (R2=0.94) so that this equation could be used to predict the CExp. of AHSS by RSW. The extent of the effects of the alloying elements on the CExp. was in the order of Si, Al, C, Mn and Cr. From the correlations among the CExp. and resistivity (R), the coefficient of thermal expansion (α) and yield strength (Y.S1200℃), the CExp. was calculated to be CExp. (kA) = 9.3-0.057R -0.035α + 0.22Y.S1200℃ and the coefficient of determination was sufficiently high (R2=0.96). This equation could also be used to predict the CExp. of steel from its properties. Over the given composition range, the expulsion shape was a spray type in steel, where more than 0.5% Si was added due to the lower viscosity, melting point and high temperature yield strength. -Effect of Alloying Elements on Tensile Properties in RSW of AHSS- Regardless of the alloying elements, the specimens under 5t1/2(t=sheet thickness) were fractured at the interfacial failure mode. Pull-out failure occurred at the softened zone which was the interface of base metal and HAZ. This zone was the place where hardness was the lowest in the welds and generated by tempering of the martensite due to the welding heat. Tensile-shear load (TSL) of the welds which showed pull-out failure (PF) mode was increased with FDsz and HvSZ. Interfacial failure (IF) occurred along the interface between two spot welds specimens. Shear load (SLIF) of IF mode was dependent only on the fractured diameter. From the equation to predict SLIF of the specimen showed IF mode and TSL of the PF mode, the SLIF=β∙0.5∙σBM.W.Q (HvN / HvBM.W.Q) ∙π∙(FD/2)2and TSL= α∙t∙σBM∙(HvSZ/HvBM) ∙(ND+1.5)). Correlation coefficients between measured value and calculated value were 0.98 and 0.97 respectively. In the low current (under 6.4kA) condition, IF occurred because the real nugget diameter (ND) was smaller than the critical nugget diameter (NDCri) regardless of the alloy elements, while the PF was in the high current (over 7.4kA) condition because the ND was smaller than the NDCri.

유한요소해석을 이용한 최적용접조건의 선정에 관한 연구

강석균 한밭大學校 産業大學院 2003 국내석사

본 연구는 전기저항용접의 한 종류인 점 용접에 대한 연구이다. 강재의 용접, 특히 자동차산업에 널리 쓰이는 용접법으로 자동차 차체의 경량화와 재질의 개선을 위해 점용접의 기술개발이 필요하다. 따라서 본 연구에서는 일 타점 저항 용접부를 모델링 하여 유한요소해석을 시도하여 열전도 이론을 정식화한 후 열 탄소성 해석 및 축 대칭해석 프로그램을 개인용 컴퓨터 및 워크스테이션 환경에서 구동될 수 있도록 개발을 도모하고자 하였다. 저항 점 용접시 통전은 발열에 관계하는 모재의 함수이므로 열원은 일정 하지 않고 시간과 거리의 함수가 된다. 본 해석에서는 통전 단계에서 프로그램 해석 시 미소시간 증분마다 통전부 요소들의 온도를 계산한 후 발열량을 계산하였다. 연구에 사용된 용접기는 정치식&프로잭션 용접기이며 시험재료는 6000계열과 5000계열의 1mm 박판 이다. 시험방법은 용접 가압력을 측정하여 조절 후 용접조건을 컨트롤박스를 이용하여 통전 전류, 통전 시간을 입력한 후 용접 후 얻은 데이터를 컨트롤박스의 용접 스코프 이용하여 점검한 후 컴퓨터에 데이터를 입력시켰다. 사용된 시험에는 인장전단시험, 비틀림 시험을 실시하였다. 시험결과 온도분포는 5052 알루미늄 합금이 높은 온도분포를 보였으며 최적용접 조건으로 선정되는 8cycle(0.13sec)에서 최대온도를 나타내었고 인장강도에서는 6061합금이 비교적 우수하였다. 너깃 직경 변화에서는 최적 용접조건에서의 너깃과 인장전단강도의 관계는 다른 용접조건에 비해 선형적으로 비례함을 알 수 있다. 비틀림 시험에서는 통전 전류 크기를 변환시켜도 비틀림 강도는 그다지 크게 변하지 않음을 알 수 있다. 이러한 결과로 보아 본 연구를 통해 차후 잔류 응력 및 열탄소 해석을 가능 하게 할 수 있으며 첨단화된 점용접의 연구에 도움이 될 수 있을 것으로 사료된다. For many years now resistance spot welding has assumed a dominant role in the manufacturing industry, particularly in the production of automotive parts and white goods. Its extensive use is primarily due to the simple and flexible nature of the technology, which has made successful automation of the process possible. Therefore, In the case of resistance welding, the choice of the optimum welding parameters may be extremely dependent on the material, possibly even on the batch in question. Mathematical optimisation methods were therefore applied and assessed in order to determine the welding range and the optimum welding parameters(welding duration, welding current and electrode force). The target variable was the highest possible tensile shear force of the welded spot. It was shown that the modified simples method was the most suitable method. The mechanical properties of spot weld of aluminum alloy were evaluated by tensile shear test, torsion test and by peel test at room temperature. In order to have a better understanding on weldability, the baslc experiments were performed after conducting pre-tests with the same material and the finite element modeling. The numerical analysis of mechanical behavior as well as heat conduction is carried out for the spot welding process. For this numerical analysis, axial symmetric computer program for the spot welding analysis by F.E.M, has been developed considering heat conduction and thermal elastic-plastic theory. Material properties depending on temperature such as density, heat conductivity, heat expansion coefficient, specific heat, yield stress, elastic modules, and specific resistance considered. Using the results of temperature distribution obtained from heat conduction analysis, the thermal elastic-plastic analysis is carried out to clarify mechanical behavior of spot welded specimen. In order to evaluate the effect of residual stresses, numerical analyses are carrid out under tension-shear load in two cases respectively. The results obtained from the mechanical and metallographic investigations revealed a strong dependency of the tensile strength of the titanium joints on the micro-structure of the weldment. The values of the critical expulsion current and the strong electrode sticking current were measured through the weld lobe test machines. Further more, it was intended to decide and develop the mass-producible aluminum alloys through the characterization and the evaluation on weldability, formability, surface treatability and mechanical properties for the aluminum alloys developed domestically. In the case of the elaborated method, it must be taken into account that knowledge about suitable initial welding parameters makes is considerably easier to find optimized parameters. The tests have shown that the optimised parameters are found using the modified simplex method but that the number of steps is extremely dependent on the starting spot.

함티탄 자철광의 환원분말을 피복한 전기용접봉의 용접 특성에 관한 연구

이양춘 부산대학교 1975 국내박사

전기저항용접 강관의 인발균열 방지를 위한 인발공정 최적화 모델 개발

이동활 부산대학교 대학원 2004 국내석사

For the large reduction in tube cross section, the tube drawing process is usually performed by two successive passes. In multi-pass drawing process, the balance in drawing strains is important to prevent drawing cracks. Therefore in this study, the model for uniform strain distributions in two-pass drawing process has been developed on the basis of cross sectional variation of drawn tube. For the given product geometry the model provides optimal diameter and thickness that can evenly distribute drawing stains. The capability of model is well confirmed by finite element analysis of tube drawing process. Criteria curves at variation limit strains to determine whether the drawn tube would fail during drawing process are also proposed by newly developed model.

전기저항용접 강관의 홈부식 기구 연구

서도수 울산대학교 대학원 1998 국내석사

퍼스날 전기 용접기 분석 및 제품디자인 개발

김영호 신라대학교 일반대학원 2016 국내석사

디자인행위는 디자인의 고유한 형태적 접접 뿐 아니라 디자인에서 느낄 수 있는 인간의 암묵적 행위인 인지적 표현으로 형태를 느끼고, 즐기며, 생각한다. 본 연구에서의 디자인 방향을 개인의 용접기 디자인의 개발 프로세스의 일반적인 산업적 프로세스를 연구하면서도 디자인의 표현적인 구체성을 디자인공식으로 해석하려 노력하였으며 이러한 절차를 통해 표현하는 디자인연구는 디자인 개발의 명확한 방향성과 실무적인 표현이 무엇보다 중요한 연구라 말 할 수 있다. 이러한 다 학제적인 디자인 연구에 대한 디자인적용방향을 살펴보고 디자인 개발의 의미를 탐색할 수 있다. 디지털화, 기계화 정보화 되어진 현 사회에서 개인의 만족과 가치를 높이는 개인작업에 대한 욕구는 점점 열기가 높아가는 현실에서 용접기라는 특수한 분야의 이론적 고찰과 제품의 다양성을 접할 수 있는 선행연구를 바탕으로 디자인이 서비스적인 측면에서 학문의 꼭지점에 있음을 확인시켜 주고자 하였다. 디자인은 소비자중신의 사고에서 벗어나면 위험한 경제적 불이익을 당 할 수 있지만 반대로 생각하면 경제적인 이익 때문에 왜면 받는 소비자가 나올 수도 있는 것이다. 이러한 뒤편에 내몰린 소비자의 감성을 어루만지고 소비자의 본연의 소비자권리를 회복시키기 위해서는 산업 제품으로 분류된 용접기를 합리적 기준으로 제작하여 제품 사용자가 안전하고 경제적인 만족을 느끼면서 사용할 수 있는 제품개발이 절실함을 알 수 있었다. 이러한 산업 용접기도 산업에서 사용하는 경우가 대부분이지만 개인의 작업욕구를 충족시키는 환경에서의 사용 가능성이 점점 높아지므로 개인용 용접기의 분석 및 제품디자인 개발이 더욱 필요한 것이다. 개인 용접기의 가장 두드러지는 디자인형태적 특징은 제품의 기능적 서비스를 만족시킬 수 있는 형태적 서비스가 선행되어야 하며 각 제품의 디자인적 획일성 / 통합성 / 기능성을 창의적이고 독자적인 디자인 IDENTITY로 인간의 감성만족을 디자인으로 서비스 하여야한다. 본 연구에서는 실질적인 디자인 개발과 더불어 디자인의 개발프로세스 사고과정에 대한 문제해결방법과 디자인프로세스로 접근하여 아이디어 스케치와 디자인 이미지맵, 색채적인 특징연구, 기술적 접근 및 재료의 특성까지 고려한 디자인을 개발하였다. 또한 합리적이고 융합적 실무방향으로 기능의 특성을 높일 수 있는 좋은 기술로 부각되기 위하여 3차원 렌더링을 제작하여 디자이너의 고유한 기술한 감성적 디자인 서비스의 전 과정을 디자인행위로 연구하고자 하였다. 개발에 있어 디자인관점은 소비자와 개발자의 합목적관점의 사고과정이 필요하며 이러한 양쪽관계를 디자이너의 논리적 표현으로 절차적 문제해결방향 해결방향을 모색하고 연구하는 중요과정이 디자인 과정이며 이러한 해결을 위한 문제점을 결과물에 대한 해결과정을 통하여 양산하는 소비자 용구에 충족하는 다품종 소량생산을 목표로 신제품을 개발하고자 하였다. 제품디자인 개발은 기업의 경제적 목표를 달성하기 위한 문제해결의 중요과정이며 제품디자인 이익에 부합된 결과물로 이끌 수 있는 것이 무엇보다 중요하다. Design activity involves not only its inherent morphological aspects but also a series of psychological aspects including sense, enjoyment, and thought in its perceptual expressions to be implicatively interpreted by humans. Although this study approached a design process of personal electric welding machines in a category of a generalized industrial process, significant efforts were made to analyze expressional concreteness and diversity based on design principles. Such a design study in pursuit of an effective solution for product design can be regarded as a multidisciplinary research spanning cognitive psychology, artificial intelligence, anthropology, philosophy, and computer science. This study has a significant value in proposing a novel design process to accomplish more systematic and specialized product development by broadening design applications to multidisciplinary areas and switching emotional concepts to reasonable and concrete expression in design outputs. In a modern society which is matured with digitization, mechanization and informatization, desires over a personalized process to realize self-oriented satisfaction and values in product design are increasing. In this trend, this study provides a theoretical analysis and literature reviews on various product designs in a specialized field of welding machines. Based on such analysis, this paper aims to verify the high-level role and values of design in multidisciplinary fields associated with productional services. Product design tends to focus on the majority of customers for maximizing economic profits. Ironically, this tendency can minimize the majority of design preferences which customers might possess. Therefore, a novel design process of personalized welding machines in a reasonable standard can substitute industrial welding machines with expanding customers' rights in choosing their preferred design and reflecting their own design sensitivity to actual products. Such a design process can contribute to the enhancement of customer's safety and economic satisfaction. Although industrial welding machines are generally utilized in industrial fields rather than personalized jobs, analysis and research on personal welding machines and their product design are indispensable to improve their usability and suitability in personalized jobs. This study recognized the most crucial factor in design of personal welding machines as a morphological feature to satisfy its functional priority. In addition, a creative and unique design in uniformity, unification, and functionality can be regarded as a design IDENTITY to emotionally satisfy customer's preference. This study developed a series of design process consisting of idea sketches, image maps, coloristic features, technical approaches and material properties based on problem-solving approaches as a perceptual design process. In addition, actual design samples through the process are demonstrate to validate its efficiency and practicality. Furthermore, to provide qualitative and scientific analysis on the preposed design method, 3D renderings of design outputs are presented to validate how accurately designer's emotional factors are expressed and reflected to the design outputs.

자동차용 강판의 전기저항 점용접부 열처리에 의한 인장전단강도 특성

이현철 동의대학교 산업대학원 2008 국내석사

The characteristics of tensile shear strength in resistance spot weld of 0.8㎜ thick galvanizing automobile steel plate(SGARC35) under heat treatment were investigated by tensile-shear strength tests. Optimized welding conditions of resistance spot welding were fixed welding time and welding force with change of welding current. The specimens were heat-treated by the temperature of RT, 70°C, 150°C and 250°C during 1 hour and cooled by air, respectively. Then, Tensile shear strength tests were performed in accordance with KS B0851. The results of this experimental investigation are as follows; 1) Maximum loads are increased with increasing welding current at 12cycle welding time and 270MPa welding force. Maximum loads at the specimen of both heat treated and as-welded are similar trend. but maximum loads were decreased with increasing heat-treated temperature. 2) Tensile shear strengths are increased with increasing welding current at 12cycle welding time and 270MPa welding force. Tensile shear strength were high as 11.5㎄ welding current. 3) Tensile shear strengths and maximum loads of as-welded specimens are high at 11.5㎄ welding current. but tensile shear strengths and maximum loads of heat-treated specimens were low at 7.5㎄ welding current and 250°C heat-treated temperature. 4) Penetration size of nugget shape were increasing with increasing welding current. but blow hole, expulsion and surface flash were decreased. Weldability, maximum loads and tensile shear strengths were high at 11.5㎄ welding current.