Ji-Yeon Shim

A Study on Distributions of Electromagnetic Force of the Dissimilar Metal Joining in MPW Using a FEM

Recent trends of welding system have been focused on the development of new process in order to achieve better quality, higher productivity and friendly to the environmentally in welding process. The Magnetic Pulse Welding(MPW) process is based on the principle of a tremendous amount of energy compressed and discharged for an extremely short period of time. The purpose of this paper is to investigate welding characteristics according to the distributions of an electromagnetic force on the weldment using a finite element method and to find the optimal process parameters such as input current and frequency. To successfully accomplish this objective, a 2-dimensional axisymmetric electromagnetic numerical model has firstly been developed. The equation was solved using a general electromagnetic mechanics computer program, ANSYS code. The comparison between the calculated and measured results has been carried out to verify the developed system.

Development of Working Coil for Magnetic Pulse Welding

출원번호출원명 출원인출원연도US6977361 Molecular bonding of vehicle frame components using magnetic impulse welding techniquesDana Co. Ltd. 2005US687596 Apparatus for electromagnetic forming, joining and weldingFord Motor Company 2005US6548791 Energy storage apparatus and inductor tools for magnetic pulse welding and formingInli, LLC 국외 전자기 펄스 용접 기술은 이스라엘 Pulsar사의 2003US6389697 Fabricating automotive spaceframes using electromagnetic forming or magnetic pulse weldingFuel Cell and Integrators, Inc. 2002US6104012Molecular bonding of vehicle frame components using magnetic impulse welding techniquesDana Co. Ltd. 2000US5981921Method of magnetic pulse welding an end fitting to a driveshaft tube of a vehicular driveshaftDanaCo. Ltd. 1999US5824998Joining or welding of metal objects by a pulsed magnetic forcePulsar Welding Ltd. 1998* 「마그네틱 응용기술 및 시장분석」 (주) 비아글로벌 2006

A Study on Development of STACO Model to Predict Bead Height in Tandem GMA Welding Process

One of the main challenges of the automatic arc welding process which has been widely used in various constructions such as steel structures, bridges, autos, motorcycles, construction machinery, ships, offshore structures, pressure vessels, and pipelines is to create specific welding knowledge and techniques with high quality and productivity of the production-based industry. Commercially available automated arc welding systems use simple control techniques that focus on linear system models with a small subset of the larger set of welding parameters, thereby limiting the number of applications that can be automated. However, the correlations of welding parameters and bead geometry as welding quality have mostly been linked by a trial and error method to adjust the welding parameters. In addition, the systematic correlation between these parameters have not been identified yet. To solve such problems, a new or modified models to determine the welding parameters for tandem GMA (Gas Metal Arc) welding process is required. In this study, A new predictive model called STACO model, has been proposed. Based on the experimental results, STACO model was developed with the help of a standard statistical package program, MINITAB software and MATLAB software. Cross-comparative analysis has been applied to verify the reliability of the developed model.

A Study about Analysis of Weld Distortion using Genetic Algorithm

Abstract In the process to manufacture for metallic structures, control of welding deformation is one of an importantproblems connected with reliability of the manufactured structures so that welding deformation should be measured and controlled with quickly and actively. Also, welding parameters which have as lot of effects on welding deformation such as arc voltage, welding current and welding speed can also be controlled. Theobjectives for this study were to develop a simple 2-D FEM to calculate not only the transient thermalhistories but also the sizes of fusion and heat-affected zone (HAZ) in multi pass arc welds including the butt and fillet weld type with dissimilar thickness, and to concentrate on a developed model for the finding the parameters of Godak’s moving heat source model based on a GA. The developed model includes a GA program using MATLB and GA toolbox, and a batch mode thermal model using ANSYS software. Not only the thermal model was verified by comparison with Goldak’s work but also the developed model was validated with molten zone section experimental data.Key Words : Weld distortion, Genetic algorithm, Double-ellipse heat input model, Finite element method

Principle and Application of Magnetic Pulse Welding

최근 금속가공산업은 자동차, 조선 기계, 전자 등의 부품소재 제조에 있어 핵심적인 산업으로 자리하고 있다. 특히 가장 많은 비중을 차지하고 있는 용접산업은 저임금을 바탕으로 한 중국기술의 추격과 선진국의 고품질화에 직면하고 있으며 이러한 문제를 해결하기 위하여 친환경 공정기술의 개발과 신기술을 통한 제품의 부가가치 제고가 요구된다. MPW는 자기장에 의한 전자기력을 사용하므로 물리적인 접촉 없이 금속을 가공하는 방법으로서, 용접(brazing과 soldering 포함), 금형 및 소성가공공정에서 환경오염 발생원인 용접재료, 가스, 용가재, 플럭스, 윤활유 및 세척유 등이 필요 없이도 고품질의 제품을 생산할 수 있는 친환경적인 공정기술이다. 그 외에도 도금된 상태에서 작업이 가능하여 기존의 공정에서 결함이 발생되었을 때 재도금을 실시하는 후공정이 생략되어 도금공정에서 배출되는 오염물질도 줄일 수 있고, 작업이 수 μs 하에서 이루어지기 때문에 전력소모가 매우 적으며 작업시간을 절약할 수 있는 장점을 갖고 있다

A Study on Analysis of Weld Distortion in Multi‐pass Arc Welding

Since prediction and control of welding deformation are one of an important problems connected with reliability of the manufactured structures, welding deformation should be measured and controlled with quickly and actively. Also, welding variables which have lots of effects on welding deformation such as arc voltage, welding current and welding speed can also be controlled. This study focuses on development of a simple 2D(a two‐dimension) FEM(Finite Element Method) to calculate not only the transient thermal histories, but also the sizes of Fusion Zone(HZ) and Heat‐Affected Zone (HAZ) in multi‐pass arc welding including the butt weld type with dissimilar thickness, and to develop the new model for finding the parameters of Godak’s heat source model based on a GA(Genetic Algorithm). The developed model included a GA program using MATLB and GA toolbox, and a batch mode thermal model using ANSYS software. The thermal model was verified by comparison with Goldak’s work and the molten zone section from obtain...

Prediction model for bead reinforcement area in automatic gas metal arc welding

Automatic welding systems are widely used for high-volume production industries, where the cost of related equipment is justified by the large number of pieces to be made. Detailed movement devices are required, including predetermined welding parameter sequences and timers, to form the weld joints. Automatic gas metal arc welding processes require new mathematical models to predict optimal welding parameters for a given bead geometry to accomplish the desired mechanical properties of the weldment. The developed algorithm should be able to be employed across a wide range of material thicknesses and all welding positions, and available in analytical form to be easily applied to the welding robot with high degree of confidence in predicting bead dimensions. Therefore, this study investigated welding voltage, arc current, welding speed, contact tube weld distance, and welding angle on bead reinforcement area for automated gas metal arc welding processes using a central composite design to generate response surface methodology and artificial neural network models. Average absolute deviation was used to compare accuracy between the two models. Analysis of variance showed coefficients of determination of 0.894 and 0.948 with average absolute deviation 4.01% and 3.11% for the response surface methodology and artificial neural network models, respectively. This suggests that artificial neural network is a better modeling technique for predicting bead reinforcement area compared to response surface methodology.

Development of Electrohydraulic Forming Process for Aluminum Sheet with Sharp Edge

Electrohydraulic forming (EHF), high-velocity forming technology, can improve the formability of a workpiece. Accordingly, this process can help engineers create products with sharper edges, allowing a product’s radius of curvature to be less than 2 mm radius of curvature. As a forming process with a high-strain rate, the EHF process produces a shockwave and pressure during the discharge of an electrical spark between electrodes, leading to high-velocity impact between the workpiece and die. Therefore, the objective of this research is to develop an EHF process for forming a lightweight materials case with sharp edges. In order to do so, we employed A5052-H32, which has been widely used in the electric appliance industry. After drawing an A5052-H32 Forming Limit Diagram (FLD) via a standard limiting dome height (LDH) test, improvements to the formability via the EHF process were evaluated by comparing the strain between the LDH test and the EHF process. From results of the combined formability, it is confirmed that the formability was improved nearly twofold, and a sharp edge with less than 2 mm radius of curvature was created using the EHF process.

A Study on Magnetostrictive Sensor for Detecting the Weld Defects

Industries such as gas, oil, petrochemical, chemical, and electric power have generally employed for the operation and used to enlarge the equipment or structures that require a high capital investment. In order to meet these requirements, the industries are increasingly moved toward saving the experimental verifications and computer simulation. Therefore industries to reduce the maintenance costs without compromising operational safety have been forced on finding better and more efficient methods to inspect their equipment and structures. It was motivated to meet the industrial needs and to secure and maintain the institutes technical initiative and leadership in the development of this new and exciting technology. Also, the system with many sensors could be detected the weld defects, and was useful for real-time monitoring. This paper is focused on the development of the real-time non-contract monitoring system as an efficient tool for the experimental study of weld defects based on the relationship between the measured voltage and input parameters. The monitoring technology involves the use of Ms S (Magnetostrictive Sensors) for the generation and detection of the guided waves. The developed system was employed to the experimental study in order to fine the weld defects for steel object with artificial defects used in the welding field.

Application of Magnetic Pulse Welding for Manufacturing Automobile Parts

배기가스 및 연비와 직결되어 있는 자동차 중량 절감의 중요성이 강조됨에 따라 자동차 경량화 기술은 환경 친화적인 자동차 개발의 핵심기술로 연구되고 있다. 그러나 소비자의 편의성 추구, 안전기준의 강화 등으로 중량은 지속적으로 증가하고 있어 이를 혁신적으로 절감할 수 있는 기술 개발이 요구된다. 따라서 차체 중량의 경량화를 위한 새로운 가공 및 조립 기술의 개발, 최적화 설계 기술 도입 등이 고려되고 있으며 특히, 대체 경량 재료의 적용에 연구가 집중되고 있다. Table 1은 국외 자동차업체에서 고급차종의 차체 및 부품에 적용되고 있는 강재를 알루미늄, 마그네슘과 같은 경량재로 대체하여 스페이스 프레임에 적용한 사례이다