While automatic welding process has been introduced at the manufacturing site today to improve the welding efficiency and weldment quality, there are still some joint which is difficult to be automatically welded. Horizontal penetration bead welding in Shipyard, for instance, where weld pool shape varies easily and tracing technique for its variation is required, is manually welded by skilled welder. In order to automate such skillful welding, our research team works on development of weld pool recognition technique with visual sensor and control robot system. In this research, feature points of weld pool are recognized by using CNNs based learning model in real time during CO 2 welding on V-groove joint with gap variation. The chemical composition of the flux cored wire is specially designed for bridge performance and back bead quality. It is adopted the straight stepped weaving to adapt a weld pool shape with gap variation. In order to reduce work processes of ceramic backing attachment, with and without ceramic backing welding has been studied in this research. From the images by a CMOS camera, it is confirmed that the pool lead length and width ( PL L , PL W ) which are calculated by feature points are recognized with high accuracy by CNNs learning model. On the other hand, it is also found that a large corpus of labeled images is required to obtain the high performance of learning model. In order to reduce costly expert annotation, we propose a self-training method which uses unlabeled images. As a result, it is confirmed that the PL L and PL W are recognized accurately by the self-training method proposed. Finally, results of demonstration of automatic welding with real time image recognition and robot control are described. These results show that horizontal penetration bead welding with and without ceramic backing is possible to be automated by robot system proposed.
{"title":"Automatic penetration bead welding technology in horizontal position using weld pool image recognition","authors":"Keitaro Ozaki, N. Furukawa, Akira Okamoto, Keito Ishizaki, Yuji Kimura, Takeshi Koike","doi":"10.2207/qjjws.39.309","DOIUrl":"https://doi.org/10.2207/qjjws.39.309","url":null,"abstract":"While automatic welding process has been introduced at the manufacturing site today to improve the welding efficiency and weldment quality, there are still some joint which is difficult to be automatically welded. Horizontal penetration bead welding in Shipyard, for instance, where weld pool shape varies easily and tracing technique for its variation is required, is manually welded by skilled welder. In order to automate such skillful welding, our research team works on development of weld pool recognition technique with visual sensor and control robot system. In this research, feature points of weld pool are recognized by using CNNs based learning model in real time during CO 2 welding on V-groove joint with gap variation. The chemical composition of the flux cored wire is specially designed for bridge performance and back bead quality. It is adopted the straight stepped weaving to adapt a weld pool shape with gap variation. In order to reduce work processes of ceramic backing attachment, with and without ceramic backing welding has been studied in this research. From the images by a CMOS camera, it is confirmed that the pool lead length and width ( PL L , PL W ) which are calculated by feature points are recognized with high accuracy by CNNs learning model. On the other hand, it is also found that a large corpus of labeled images is required to obtain the high performance of learning model. In order to reduce costly expert annotation, we propose a self-training method which uses unlabeled images. As a result, it is confirmed that the PL L and PL W are recognized accurately by the self-training method proposed. Finally, results of demonstration of automatic welding with real time image recognition and robot control are described. These results show that horizontal penetration bead welding with and without ceramic backing is possible to be automated by robot system proposed.","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67996045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Tadano, Y. Nakatani, T. Hino, Haruki Ohnishi, Daisuke Tsuji, Tooru Tanaka
In additive manufacturing of metal products, predicting deformations induced during the process is indispensable for improving the quality of the products and reducing the post-process machining time. Finite element analysis (FEA) based on the inherent strain method using a voxel mesh is an effective prediction method due to its reasonable analysis time, and to efficiently implement the prediction, a method of easily and accurately defining the inherent strain value is required. In this study, an analysis method based on multi-layer model theory was proposed to evaluate the inherent strain applicable to electron beam melting. The inherent strains obtained by the analysis were - 0.835% and - 3.42% for 12Cr steel and Co alloy, respectively. As a verification result using the FEA based on the analyzed inherent strain, the out-of-plane deformation of the base plate and the thickness of the manufactured parts were evaluated with accuracies of ± 2.0mm and ± 0.5mm, respectively.
{"title":"Inherent Strain Analysis Using Experimental Multi-layer Model for Electron-Beam-Melted Parts","authors":"S. Tadano, Y. Nakatani, T. Hino, Haruki Ohnishi, Daisuke Tsuji, Tooru Tanaka","doi":"10.2207/QJJWS.39.1","DOIUrl":"https://doi.org/10.2207/QJJWS.39.1","url":null,"abstract":"In additive manufacturing of metal products, predicting deformations induced during the process is indispensable for improving the quality of the products and reducing the post-process machining time. Finite element analysis (FEA) based on the inherent strain method using a voxel mesh is an effective prediction method due to its reasonable analysis time, and to efficiently implement the prediction, a method of easily and accurately defining the inherent strain value is required. In this study, an analysis method based on multi-layer model theory was proposed to evaluate the inherent strain applicable to electron beam melting. The inherent strains obtained by the analysis were - 0.835% and - 3.42% for 12Cr steel and Co alloy, respectively. As a verification result using the FEA based on the analyzed inherent strain, the out-of-plane deformation of the base plate and the thickness of the manufactured parts were evaluated with accuracies of ± 2.0mm and ± 0.5mm, respectively.","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67996155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Wonthaisong, S. Shinohara, K. Shinozaki, R. Phaoniam, Motomichi Yamamoto
The purpose of this study was to develop a high-efficiency and low-heat-input CO 2 arc-welding process using hot-wire feeding. A previous paper showed that the proposed hot-wire CO 2 arc-welding process has the potential to simultaneously achieve both high efficiency and low heat input. This paper investigated the production of a sound joint with only two welding passes on a butt joint of 20mm-thick steel plates with no defects or unstable welding phenomena using the developed hot-wire CO 2 arc-welding process. Welding condition optimization was investigated using high-speed imaging and cross-sectional observations. The optimized conditions, which were the combinations of the welding current and hot-wire feeding speed as 350A and 7.5m/min, 400A and 5m/min, 450A and 5m/min, 500A and 5m/min, derived to avoid the presence of defects and molten metal precedence, which achieved sound welded joints possessing adequate properties of strength and toughness.
{"title":"Evaluation of Butt Joint Produced by a Hot-Wire CO2 Arc Welding Method","authors":"S. Wonthaisong, S. Shinohara, K. Shinozaki, R. Phaoniam, Motomichi Yamamoto","doi":"10.2207/QJJWS.39.96","DOIUrl":"https://doi.org/10.2207/QJJWS.39.96","url":null,"abstract":"The purpose of this study was to develop a high-efficiency and low-heat-input CO 2 arc-welding process using hot-wire feeding. A previous paper showed that the proposed hot-wire CO 2 arc-welding process has the potential to simultaneously achieve both high efficiency and low heat input. This paper investigated the production of a sound joint with only two welding passes on a butt joint of 20mm-thick steel plates with no defects or unstable welding phenomena using the developed hot-wire CO 2 arc-welding process. Welding condition optimization was investigated using high-speed imaging and cross-sectional observations. The optimized conditions, which were the combinations of the welding current and hot-wire feeding speed as 350A and 7.5m/min, 400A and 5m/min, 450A and 5m/min, 500A and 5m/min, derived to avoid the presence of defects and molten metal precedence, which achieved sound welded joints possessing adequate properties of strength and toughness.","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67996243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"FEM Simulation of Stress Fields During Resistance Spot Welding","authors":"Manabu Fukumoto, H. Ueda","doi":"10.2207/JJWS.90.194","DOIUrl":"https://doi.org/10.2207/JJWS.90.194","url":null,"abstract":"","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68676925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Technique for Preventing Solidification Cracking at the end part in One-Side Submerged Arc Welding","authors":"Hiroyoshi Yokota","doi":"10.2207/JJWS.90.269","DOIUrl":"https://doi.org/10.2207/JJWS.90.269","url":null,"abstract":"","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68677708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Developing the Innovative Digital Twin and Its Fundamental Technologies","authors":"Ryoji Nakamura, Yoshiaki Takeuchi","doi":"10.2207/JJWS.90.5","DOIUrl":"https://doi.org/10.2207/JJWS.90.5","url":null,"abstract":"","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68679219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fatigue crack propagation stage is considered to be the dominant in fatigue fracture of welded joints and some solutions regarding stress issue have been developed. It is known that fatigue crack forms slip band at crack tip and propagates by accumulation of irreversible deformation against cyclic loading. Then if angle difference between (110) plane which is the main slip plane of body centered cubic lattice and the plane of which angle is 45 ° to the crack plane with respect to crack propagation direction is maximum, suppression of fatigue crack growth is expected. And the delay of fatigue crack growth is also expected, when the compressive stress is developed in the steel plate. In the present study, fatigue crack path and fatigue crack growth rate in the test steel with highly oriented texture and internal stress distribution were investigated. The angular difference with (110) plane and crack plane got largest by accumulating the (110) plane perpendicular to the plane thickness direction and propagating the crack in the thickness direction. Fatigue crack growth rate of steel with highly oriented texture was lower than that of normalized steel, and the crack growth was remarkably suppressed when compressive stress was superimposed inside the steel plate. It is considered that crack closure effect by fracture surface contact with increase of the fracture surface ruggedness appeared, because fatigue crack branching and bending in steel with highly oriented texture were observed.
{"title":"Investigation on the Influence of Highly Oriented Texture and Internal Stress on Fatigue Crack Growth","authors":"Takashi Hiraide, T. Handa, S. Igi","doi":"10.2207/qjjws.39.406","DOIUrl":"https://doi.org/10.2207/qjjws.39.406","url":null,"abstract":"Fatigue crack propagation stage is considered to be the dominant in fatigue fracture of welded joints and some solutions regarding stress issue have been developed. It is known that fatigue crack forms slip band at crack tip and propagates by accumulation of irreversible deformation against cyclic loading. Then if angle difference between (110) plane which is the main slip plane of body centered cubic lattice and the plane of which angle is 45 ° to the crack plane with respect to crack propagation direction is maximum, suppression of fatigue crack growth is expected. And the delay of fatigue crack growth is also expected, when the compressive stress is developed in the steel plate. In the present study, fatigue crack path and fatigue crack growth rate in the test steel with highly oriented texture and internal stress distribution were investigated. The angular difference with (110) plane and crack plane got largest by accumulating the (110) plane perpendicular to the plane thickness direction and propagating the crack in the thickness direction. Fatigue crack growth rate of steel with highly oriented texture was lower than that of normalized steel, and the crack growth was remarkably suppressed when compressive stress was superimposed inside the steel plate. It is considered that crack closure effect by fracture surface contact with increase of the fracture surface ruggedness appeared, because fatigue crack branching and bending in steel with highly oriented texture were observed.","PeriodicalId":39980,"journal":{"name":"Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67995856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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