용접이상화에 의한 용접부정의 예측과 정도

이재익,장경호,김유철,Lee, Jae-Yik,Chang, Kyong-Ho,Kim, You-Chul 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.5

In order to reduce a grand compute time in prediction of welding distortion and residual stress by 3D thermal elastic plastic analysis, idealization of welding that is methods to heat input simultaneously in all weld metal on the same welding direction is carried out on two weld joints(butt welding and fillet welding). Then, the accuracy of acquired results is investigated through the comparison of the high accuracy prediction results. The thermal conduction analysis results by idealization of welding, the temperature is raised accompany with beginning of heat input because all of weld metal is heated input at the same time. On the other side, the temperature witch predicted with high accuracy is raised at the moment heating source passes the measuring points. So, there is difference of time between idealization of welding and considering of moving heat source faithfully. However, temperature history by idealization of welding is well simulated a high accuracy prediction results.

자동차용 박강판의 Spot 용접시 통전방식에 따른 용접특성에 대한 연구

이성호 ; 조휘창 김천대학교 1995 김천대학교 논문집 Vol.16 No.-

The mechanical properties and nugget feature for thin plated steel studied in current cntrol types of spot welding. Test pieces, used in this study, prepared for following - thin plated steel for a car body. For the influence of welding current control types, it appeared annealing effect in the slope control welding. In the pulsation weld-ing, tensile shear strength appeared high on the short cooling time, and hardness appeared high on the long cooling time, in temper welding showed the same trend with single impulse welding.

초음파 용접을 이용한 전선의 접합

이철구,황병주,허인호 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.4

In this study, the purpose finds out the best welding conditions for bonding of electric wire by ultrasonic welding. The material was plastic-insulating low-voltage cables for automobiles. The experiment varied the values of welding time and welding pressure and fixed the values of amplitude and energy. With the facts, the best condition for ultrasonic welding to achieve bonding exactly is gained according to the size of the cross-sectional area of the cable, and the adhesive intensity is greatly influenced by the variables of welding time and weld-ing pressure. Also when the welding time and welding pressure increase as the cross-sectional areas of the cable increase, the welding result is gained exactly.

APPROACH TO ASSESS A FAST WELDING SIMULATION IN AN INDUSTRIAL ENVIRONMENT - APPLICATION FOR AN AUTOMOTIVE WELDED PART

W. PERRET,R. THATER,U. ALBER,C. SCHWENK,M. RETHMEIER 한국자동차공학회 2011 International journal of automotive technology Vol.12 No.6

Fusion welding processes are widely used for joining metal structures, such as pipes, ships, and cars. In general, these joining processes offer a very good compromise between reliability, safety, cost and maintenance which are important issues in the current economical context. The negative heat effects of welding, i.e. distortions and residual stresses of the welded parts, are well known and many researches in this field have already been done in the last decades in order to minimize them. On the experimental side, many sophisticated procedures have become state of the art to deal with this problem. On the computational side, the improvement of the simulation algorithms and the computing power enables the simulations of many physical phenomena occurring during the welding process. The implementation of welding simulation techniques is nevertheless not an easy task and often associated with expert knowledge which hinders their global application in an industrial environment. This paper is focused on the industrial requirements of a welding simulation software with special respect to the needs of the automotive industry. The necessary information to run a welding simulation and the expectations of a weld specialist without deep knowledge in numerical methods are investigated. These expectations are tested on an automotive welded assembly with a commercially available welding simulation software designed especially for the needs of the automotive industry. A welding experiment is done and the measured temperature distributions and distortions serve as reference to validate the simulation results. The result quality of the simulations of temperature fields and distortions is in best agreement with experimental data. The workflow is well adapted for the considered industrial requirements and the time-tosolution as well as the computational costs are acceptable, whereas the efficient calibration of the heat input model is still a point which will be further investigated in current and future research works.

시계열 데이터를 이용한 딥러닝 기반 용접 공정 모니터링 리뷰

이재헌,황환이,정태순,김덕용,안정빈,이규찬,이승환 대한용접접합학회 2024 대한용접·접합학회지 Vol.42 No.4

The quality of welds during welding processes significantly affects the performance and the reliability of the final products. Therefore, to guarantee a high quality of the products, technologies that utilize time-series data measured by various sensors for monitoring the welding processes are required. Because the time-series data measured during the welding processes exhibit nonlinear and nonstationary characteristics, deep learning techniques, which can automatically learn the features of nonlinear and nonstationary signals through deep network structures, have recently gained recognition as a new monitoring method. Therefore, in this review, recent research that applied deep learning models based on time-series data measured during welding processes to monitor welding processes are introduced. In addition, the types of time-series data and deep learning model structures that are predominantly used to monitor the welding processes, such as predicting the penetration states and identifying the welding defects are discussed. Lastly, based on the research cases discussed herein, future research directions and the prospects of deep learning- based welding process monitoring technology that uses time-series data are discussed.

빅 데이터(Big Data)를 이용한 용접품질에 연구

김일수(Ill Soo Kim),신윤덕(Yun-De Shen) 제어로봇시스템학회 2021 제어·로봇·시스템학회 논문지 Vol.27 No.12

Generally, in welding technology, big data refers to data that is too large, fast, or complex for processing using traditional methods. For the past years, the act of accessing and storing large amounts of information for welding has been utilized. Welding technology is a central component of numerous value creation chains and plays an important role in this development. In this study, gas metal arc (GMA) welding experiments were conducted to develop an algorithm for predicting welding defects in the GMA melting process of flat plates on SS400 materials using big data technology. The correlation between various welding parameters was analyzed using the real-time measured current and voltage data during welding. In addition, the welding quality related to the weld bead was analyzed using a 3D scanner. The optimal welding parameters were predicted using a CHMM model for the welShen Yun Deding current signal in the normal welding section, which is one of the machine learning technologies. By learning this, the similarity between the normal welding current signal and the weld defect was expressed as a probability, and the changed pattern of the Log-pdf value was used to predict the welding quality.

Spectrogram Based Detection Algorithm for Back-Bead in Gas Metal Arc Welding Process using Convolution Neural Network

Chengnan Jin,Sangrin Park,Sehun Rhee 대한용접·접합학회 2021 대한용접·접합학회지 Vol.39 No.2

An automated welding system is essential to ensure a stable and good welding quality and improve productivity in the gas metal arc welding (GMAW) process. Therefore, various studies have been conducted on the establishment of smart factories and the demand for good weldability in the fields of production and manufacturing. In shipbuilding welding and pipe welding, the uniformly generated back-bead is an important criterion for judging the mechanical properties and weldability of the welded structure, and is also an important factor that enables the realization of an automated welding system. Therefore, in this study, the welding current signal measured in real-time in the GMAW process was pre-processed by a short time Fourier transform (STFT) to obtain a time-frequency domain feature image (spectrogram). Based on this, a back-bead generation detection algorithm was developed. To accelerate the training speed of the proposed convolution neural network (CNN) model, we used non-saturating neurons and a highly efficient GPU implementation of the convolution operation. As a result of applying the proposed detection model to actual welding process, the detection accuracies with and without the back-bead regions were 95.8% and 94.2%, respectively, which confirmed the excellent classification performance for back-bead generation.

용융아연도금 강판 저항 점 용접 시 정전류 및 적응제어 적용에 따른 연속타점 특성 평가 및 고찰

서정철,최일동,손홍래,지창욱,김치호,서성부,서진석,박영도,Seo, Jeong-Chul,Choi, Il-Dong,Son, Hong-Rea,Ji, Changwook,Kim, Chiho,Suh, Sung-Bu,Seo, Jinseok,Park, Yeong-Do 대한용접접합학회 2015 대한용접·접합학회지 Vol.33 No.2

With using adaptive control of the resistance spot welding machine, the advantage on electrode life time for galvanized steels has been addressed. This study was aimed to evaluate the electrode life time of galvanized steels with applying the constant current control and the adaptive control resistance spot welding process for a comparison purpose. The growth in diameter of electrode face was similar for both the constant current and the adaptive control up to 2000 welds. The button diameter was decreased with weld numbers, however, sudden increase in button diameter with use of the adaptive control after 1500 welds was observed. The peak load was continuously decreased with increasing number of welds for both the constant current and the adaptive control. The current compensation during a weld was observed with using the adaptive control after 1800 welds since the ${\beta}$-peak on dynamic resistance curve was detected at later weld time. The current compensation with adaptive control during resistance spot welding enhanced the nugget diameter at the faying interface of steel sheets and improved the penetration to thinner steel sheet.

회주철의 마찰용접 특성에 관한 연구 - 입열량 이론식을 중심으로 -

정호신,방국수,Jeong, Ho-Shin,Bang, Kook-Soo 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.3

Joining of grey cast iron by fusion welding has much difficulties for its extremely low ductility and low toughness because of the flake form of the graphite. And the brittle microstructure, i.e. ledeburite may be formed during fusion welding by its rapid cooling rates. By these kinds of welding problem, preheat and post heat treatment temperature must be increased to avoid weld crack or welding problems. In order to avoid these fusion welding problem, friction welding of cast iron was carried out for improving joint soundness, establishing friction welding variables. There is no factor for evaluating friction weldability in continuous drive type friction welding. In this point of view, this study proposed the parameters for calculating friction weld heat input. The results obtained are as follows ; 1. There was a close relationship between tensile strength and flash appearance of friction welded joint. 2. Tensile strength was decreased and flash was severely oxidized as increasing frictional heating time. 3. As increased forging pressure $P_2$, flash had a large crack and tensile strength was decreased. 4. As powdered graphite by rotational frictional force induced flat surface and hindered plastic flow of metal, tensile strength of welded joint was decreased. 5. Heat input for continuous drive type friction welding could be calculated by the factors of $P_1$, $P_2$ and upset distance(${\delta}$).

토션바 재료의 마찰용접에 관한 연구

정순억 慶尙大學校 1999 論文集 Vol.38 No.-

This thesis studied whether friction welding of SUP9A, torsion bar material could be accomplished or not. And then optimum welding conditions were examined and leaded through tensile, impact, torsion and hardness test after postweld heat treatment of the actual field condition. Obtained results were as follows; Linear relationship was existed between heating time and total upset, and a quadratic equation model could be made between tensile strength and heating time. Optimum welding conditions with fine structure were as follows in case total upset(U)=8.3mm; the number of rotations(n)=2,000 rpm, heating pressure(p1)=80 MPa, upset pressure(p₂)=200 MPa, heating time(t₁)=4 sec, upset time(t₂)=3 sec.