• 제목/요약/키워드: Welding technique

검색결과 476건 처리시간 0.023초

Validation of Efficient Welding Technique to Reduce Welding Displacements of Ships using the Elastic Finite Element Method

  • Woo, Donghan
    • 해양환경안전학회지
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    • 제26권3호
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    • pp.254-261
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    • 2020
  • Welding is the most convenient method for fabricating steel materials to build ships and of shore structures. However, welding using high heat processes inevitably produces welding displacements on welded structures. To mitigate these, heavy industries introduce various welding techniques such as back-step welding and skip-step welding. These techniques effect on the change of the distribution of high heat on welded structures, leading to a reduction of welding displacements. In the present study, various cases using different and newly introduced welding techniques are numerically simulated to ascertain the most efficient technique to minimize welding displacements. A numerical simulation using a finite element method based on the inherent strain, interface element and multi-point constraint function is introduced herein. Based on several simulation results, the optimal welding technique for minimizing welding displacements to build a general ship grillage structure is finally proposed.

Comparisons Fitness in Implant Abutment between Gas Soldering and Laser Welding

  • Cho, Mi-Hyang;Nam, Shin-Eun
    • International Journal of Clinical Preventive Dentistry
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    • 제14권4호
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    • pp.247-255
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    • 2018
  • Objective: Osseointegration is essential process for successful implants and effects to implant in long term, therefore, passive fitness of good prosthesis is necessary. To make a good prosthesis, at first it should be done a sectioned casting and then joined method of sectioned casting body is recommended. Methods: In this study, to provide the fundamental data on stable connection method for successful implants, the author tested fitness of casting body, and compared difference between gas soldering technique and laser welding technique. Results: In fitness test of 2 abutment (test A, C), gas soldering group's fitness in the opposite part of connection was worse than laser welding group. In fitness test of 3 abutment (test B, D), gap distance was increased both in gas soldering technique and laser welding technique. Gap distance at the connecting part and the opposite part of the abutment in gas soldering technique was worse than laser welding technique and the more additional abutment, the worse gap distance in gas soldering technique. In fitness test of 3 abutment (test B, D), there's little variation in No. 2 abutment when connecting soldering process was done and there's little influence on already soldered connection part when the additional soldering connection was done. Conclusion: On weak loading condition and the part which is needed an accuracy, laser welding technique is more effective and on long-span prosthesis and frequent chewing loading part, laser welding technique is recommended first and applying additional gas soldering technique would be better for making much more successful prosthesis.

알루미늄합금의 마찰교반접합 및 그 적용 (Friction Stir Welding of Aluminium alloys and Its Application)

  • 연윤모;정승부;박종목
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2000년도 추계학술대회 논문집
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    • pp.226-234
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    • 2000
  • The friction stir welding technique is a derivative of conventional friction welding, which enables the advantages of solid-phase welding to be applied to the fabrication of long butt and lap joints, with very little postweld distortion. Friction stir welding is a remarkable new welding technique for joining aluminum alloys and has the potential for welding other ferrous materials. It has already been developed beyond a laboratory curiosity and has been proved as a potential practical welding technique offering low-distortion, high-quality, low-cost welds from simple concept machine tool welding equipment. To bring this remarkable method of welding aluminum alloys to the attention of Industry, this article introduces the basic principle of friction stir welding, pointing out the practical advantages and most important of all, describes the exceptionally good metallurgical and mechanical properties.

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Ir-192 방사선원의 밀봉 용접부 품질에 미치는 저항용접 공정변수의 영향 (The Effect of Process Parameters on Sealing Quality for Ir-192 Radiation Source Capsule using Resistance Spot Welding)

  • 한인수;손광재;이영호;이유황;이준식;장경덕;박울재;박춘득
    • Journal of Welding and Joining
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    • 제27권1호
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    • pp.65-70
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    • 2009
  • Ir-192 radiation sealed sources are widely employed to the therapeutic applications as well as the non-destructive testing. Production of Ir-192 sources requires a delicate but robust welding technique because it is employed in a high radioactive working environment. A GTA(Gas Tungsten Arc) welding technique is currently well established for this purpose. However, this welding method requires a frequent replacement of the electrode, which results in the delay of the production to take a preparatory action such as to isolate the radiation sources from the working place before getting access to the welding machine. Hence, a resistance welding technique is considered as an alternative method of the GTA welding technique. The advantages of resistance welding are high welding speed and high-rate production. Also it has very long life of electrode comparing to GTA welding. In this study, the resistance welding system and proper welding conditions were established for sealing Ir-192 source capsule. As a results of various experiments, it showed that electrode displacement can be employed as a indicator to predict welding quality. We proposed two mathematical models(linear and curvilinear) to estimate electrode displacement with process parameters such as applied force, welding current and welding time by using regression analysis method. Predicting results of both linear and curvilinear model were relatively good agreement with experiment.

유공압 밸브스풀용 강재의 봉대봉 동종재 마찰용접과 AE 평가 (Bar-to-bar similar friction welding of hydraulic or pneumatic value spools and AE evaluation)

  • 오세규;장지훈;전태언;박형동;유인종
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 1995년도 특별강연 및 춘계학술발표 개요집
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    • pp.118-122
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    • 1995
  • The hydraulic or pneumatic valve spools become essential as the important components on the production of automatic hydraulic or pneumatic machinaries as mechanical industry is developed rapidly. The machining precision is asked for manufacturing the valve spools. They could be unstable in the quality by the conventional arc welding and they have a lot of technical problems in manufacturing because their shapes are generally small. By the Precision casting process such as lost wax process, the production cost will be increased. But by the friction welding technique, they will be able to be made without such problems. Furthermore, there is a few study on friction welding of such hydraulic valve spool steels and in-process real-time weld quality evaluation technique by acoustic emission. So that, the final purpose of this study is 1) the development of design and manufacturing technique of hydraulic or pneumatic valve spool by optimizing of friction welding, and 2) the development of in-process real-time weld quality evaluation technique by acoustic emission.

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용접법의 우선순위 결정 방법 (Decision-Making Method of Priority Welding Process)

  • 김종도;김광희;윤문철
    • 한국기계가공학회지
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    • 제15권5호
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    • pp.39-47
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    • 2016
  • Nowadays, several welding processes are generally used to join parts together, and the materials are generally steel, aluminum, copper, stainless steel, and other difficult-to-weld materials. If a proper welding process is chosen, it is helpful for welding parts. However, there is no desirable technique for appropriately deciding on the welding process in the industry. Therefore, an appropriate method of selecting a welding process is needed for the novice worker in the industry. In this sense, a new analytic network process (ANP) technique is used for effective decision making in welding. By considering several criteria in ANP, a selection method is suggested to decide on the proper welding process. In the study, several criteria were considered for the proper welding of parts. By considering a matrix of prior interdependence effects among various welding processes, a decision-making method based on an ANP is accomplished using a weighting matrix, which is supposed to select an appropriate welding process. In addition, for appropriate decision criteria of the welding process, several factors, such as material, shape, precision, economics, and equipment, are used to accomplish the ANP algorithm. Moreover, the final weighting matrix is calculated following its ANP strategy. Furthermore, this decision-making technique is applied to both stainless razor spot joining and thick steel pipe joining. The results show its reliability and practicality, and the novice engineer and manager can use this technique to determine the best welding process.

크랭크 샤프트강재의 마찰용접 최적화와 AE 실시간 평가 (Optimization of Friction Welding for Crank Shaft Steels and Its Real Time AE Evaluation)

  • 오세규;최혜영;공유식
    • 한국해양공학회지
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    • 제13권4호통권35호
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    • pp.98-104
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    • 1999
  • The crank shafts need anti-corrosion materials. So STS 304 is the essential material to manufacture this shaft. However, it costs more to manufacture the shafts by using only STS 304 than welding of STS 304 to other carbon steels. And it has been difficult to weld this sort of dissimilar materials. They could be unstable in the quality by the conventional arc welding. And also they have a lot of technical problems in manufacturing. But by the friction welding technique, it will be able to be made without such problems. Then, this study aimed not only to develop the optimization of dissimilar friction welding of crank shafts steels of STS 304, SM35C, but also to develop the application technique of the acoustic emission to accomplish in-process real-time quality(such as tensile) evaluation during friction welding of the shafts by the AE technique.

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플런저용 강재의 이종재 마찰용접과 AE에 의한 실시간 평가 (Friction Welding of Dissimilar Plunger Materials and Its Real Time Evaluation by AE)

  • 공유식;조상근;김영대;오세규
    • 동력기계공학회지
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    • 제6권2호
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    • pp.48-53
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    • 2002
  • Plunger (piston rod) materials are used in high-pressure condition. So STD11 is the essential material to build this plunger. However, it costs more to make a plunger by using only STD11 than using the welding of STD11 to SCM440 and other dissimilar material. And it has been difficult to weld this sort of dissimilar materials. They could be unstable in the quality by the conventional arc welding. And also they have a lot of technical problems in manufacturing. But, by the friction welding technique, it will be able to be made without such problems. And then, on account of such reasons, we need a new approach of study on real-time quality evaluation by acoustic emission (AE) techniques as well as a domestic development of the plunger by friction welding. So that, the purpose of this study for such developments is the development of a plunger by optimizing of friction welding with more reliability and more applicability. Then, this study aimed not only to develop the optimization of friction welding of dissimilar plunger steels of STD11 to SCM440, but also to develop the application technique of the acoustic emission to accomplish an in-process real-time quality evaluation during friction welding of the plunger materials by the AE technique.

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Evaluation of the Weldability in Spot Welding using Ultrasonic Technique

  • Hong, Min-Sung;Kim, No-Hyu
    • 비파괴검사학회지
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    • 제25권3호
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    • pp.209-214
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    • 2005
  • Spot welding is the most widely used in automotive and aerospace industries. The quality of weld depends upon the size of nugget between the overlapped steel plates. Recently, the thickness of the steel plates is much thinner and hence, it introduces the smaller size of nugget. Therefore, it is necessary not only to develop the criterion to evaluate the quality of weld but also to obtain the optimal welding conditions for the better performance. In this paper, the steel plates, 0.5 mm through 1.5 mm thickness, have been spot welded at different welding conditions and the nugget sizes are examined by ultrasonic technique (C-scan type). The relationships between the nugget sizes and the weldability have been investigated. The result of ultrasonic technique shows the good agreement with that of the tensile test.

Finite Element Analysis and Measurement on the Release of Residual Stress and Non-linear Behavior in Weldment by Mechanical Loading(I) -Finite Element Analysis-

  • Jang, K.B.;Kim, J.H.;Cho, S.M.
    • International Journal of Korean Welding Society
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    • 제2권1호
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    • pp.29-32
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    • 2002
  • In previous study, the decrease and recovery of total stiffness in welded structure was discussed on the basis of experimental examination through tensile loading and unloading test of welded specimen. The recovery of structure stiffness was caused by the release of welding residual stress through mechanical loading. In this study, analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result. Thermal elasto-plastic analysis for welding process was performed by non- coupled analysis. Analysis results of welding process were transfer to elasto-plastic model for tensile loading & unloading by restart technique. In elasto-plastic analysis model for mechanical loading & unloading, hardening appearance of weld metal was considered by rezoning technique and tying technique was used for JIG condition of test machine.

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