• Journal of Welding and Joining
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• v.29 no.1
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• pp.115-122
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• 2011

This study is to propose an in-process monitoring system for micro resistance spot welding processes using minute accelerometer. A minute accelerometer is mounted on the upper moving electrode tip holder. With its high sensitivity and frequency response characteristics, accelerometer output signal has been successfully recorded and integrated twice to reflect electrode expansion during micro spot welding processes. The analysis of electrode expansion pattern was attempted to find its correlation with spot weld quality. Major previous findings1-6) regarding spot weld quality assessment with the electrode expansion signal in large scale resistance spot welding processes were proved to be true in this in-process monitoring system.

• Proceedings of the KWS Conference
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• v.43
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• pp.76-78
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• 2004

The phenomenon of weld shrinkage mainly occurs owing to residual stress by heating, which largely effects on welding quality, Actually as the shrinkage rate depends on the weld deposit amount, so it is desired that the sectional area of weld joint shall be reduced. In this respect the Electron beam welding has more profitable position compare to Narrow-gap TIG welding which is even superior to other arc welding processes. In case of thick austenitic stainless steel the shrinkage rate of Electron beam welding has about $10\%$ of Narrow-gap TIG welding's, which means that residual stress is a lot less than that of Narrow-gap TIG welding. And heat input and welded section area also indicate large difference between two processes.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.2
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• pp.152-159
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• 2005

This paper describes the application of a model-based system design method critical to complex intelligent systems, PSARE, to a welding robot development to define its top level architecture. The PSARE model consists of requirement model which describes the core processes(function) of the system, enhanced requirement model which adds technology specific processes to requirement model and allocates them to architecture model, and architecture model which describes the structure and interfaces and flows of the modules of the system. This paper focuses on the detailed procedure and method rather than the detailed domain model of the welding robot. In this study, only the top level architecture of a welding robot was defined using the PSARE method. However, the method can be repeatedly applied to the lower level architecture of the robot until the process which the robot should perform can be clearly defined. The enhanced data flow diagram in this model separates technology independent processes and technology specific processes. This approach will provide a useful base not only for improvement of a class of welding robots but also for development of increasingly complex intelligent real-time systems.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.15-21
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• 2014

FCAW(Flux Cored Arc Welding), SAW(Submerged Arc Welding), EGW(Electro Gas Welding), and three-pole SAW are applicable in manufacturing the offshore wind tower. In this paper, mechanical properties of these welded-joints for TMCP steels were evaluated in all above welding processes. The tensile strength of welded-joints for all the welding methods satisfied the standard guideline (KS D 3515). No cracking on weldment was found after the bending test. Changes of weldedments hardness with welding processes were observed. In a weld HAZ (heat-affected zone), a softened HAZ-zone was formed with high heat input welding processes (SAW and EGW). However, the welded-joint fractures were found in the base metal for all cases and small decrease in welded-joint strength was caused by a softened zone. The multi-pole SAW welds exhibited similar mechanical properties comparing to the one with one-pole SAW process.

• Journal of Welding and Joining
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• v.12 no.4
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• pp.127-140
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• 1994

Resistance spot welding has been widely used in the sheet metal joining processes because of its high productivity and convenience. In the resistance spot welding processes the size of molten nugget is a criterion to assess weld quality. Many research have founded on measuring weld nugget size at the same time monitoring welding process parameters such as dynamic resistance and electrode movement. With increasing demand of energy saving, many efforts were made to employ aluminum alloys that are lighter than steel and have relatively equivalent strength to steel in the automobile industry. In this paper, spot weldability of aluminum alloys for various welding conditions were examined by series of experiments. One of the 6000 series (Mg-Si) aluminum alloy, 6383-T4 was chosen, which is currently considered as a substitute for the galvanized steel. Dynamic resistance, electrode movement and corresponding nugget size were observed and compared to the case of steel. Finally, resistance spot welding of dissimilar material (galvanized steel-aluminum alloy) was attempted.

• Journal of Environmental Health Sciences
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• v.30 no.4
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• pp.320-328
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• 2004

A number of health hazards are generated in welding processes. In this paper, the characteristics of fumes and some other hazardous agents in welding are reviewed. Fumes in welding are generated by complex mechanism like physical ejection of particles, oxidation-enhanced vaporization, vaporization-condensation-oxidation, and spatter contribution. Fume generation rates could be described as a power function in a given process. Most of fume constituents was originated from consumables rather than base metal. The mass distribution for the welding fumes is unimodal and very small to penetrate respiratory system. So, almost fractions of fumes are classified into the respirable particulate mass. Total chromium contents in FCAW were similar to those from SMAW whereas hexavalent chromium concentrations in fume were similar to those produced from MIG welding fume. Hexavalent chromium was mostly soluble which was similar to the characteristic solubility of fume hexavalent chromium from SMAW.

• Journal of the Korean Society of Industry Convergence
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• v.11 no.2
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• pp.83-91
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• 2008

GMAW(Gas Metal Arc Welding) processes are usually used in industrial side in order to get its high productivity. But those are only adopted in the semi-automated welding equipment because of a lot of welding spatters. Many industrial robot actually percents from being engaged in the welding processes. The welding spatter problem of causes blocking them being a fully automated welding process.This study was carried out to investigate the optimal conditions for minimizing welding spatter generation at GMAW robot. The spatter can be significantly reduced below 2% of welding spatter generation at the following conditions ; First, below 18V at the wire-feed rate 2.0mm/min Second, below 23V at the wire-feed rate 3.6mm/min Third, below 24V at the wire-feed rate 5.5mm/min.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.4
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• pp.73-80
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• 2004

A dual purpose robot automation system is developed for both arc welding and spot welding by one robot within a cell. The need for automation of both arc welding and spot welding processes is urgent while the production volume is not so big as to accommodate separate station for the two processes. Also, space is too narrow for separate station to be settled down in the factory. A spot welding robot is chosen and the function for arc welding are implemented in-house at cost of advanced functions. For the spot welding, a single pole type gun is used and the robot has to push down the plate to be welded, which causes the robot positioning error. Therefore, position error compensation algorithm is developed. The basic functions for the arc welding processes are implemented using the digital I/O board of robot controller, PLC, and A/D conversion PCB. The weaving pattern is taught in meticulously by manual teach. A fixture unit is also developed for dual purpose. The main aspects of the system is presented in this paper especially in the design and implementation procedure. The signal diagrams and sequence logic diagrams are also included. The outcome of the dual purpose welding cell is the increased productivity and good production stability which is indispensable for production volume prediction. Also, it leads to reduction of manufacturing lead time.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.6
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• pp.13-19
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• 1995

A dual purpose robot automation system is developed for both arc welding and spot welding by one robot within a cell. The need for automation of both arc welding and spot welding processes is urgent while the production volume is not so big as to accommodate separate stations for the two processes. Also, space is too narrow for separate stations to be settled down in the factory. A spot welding robot is chosen and the functions for arc welding are implemented in-house at cost of advanced functions. For the spot welding, a single pole type gun is used and the robot has to push down the plate to be wolded, which causes the robot positioning error. Therefore, position error compensation algorithm is developed. The basic functions for the arc welding processes are implemented using the digital I/O board of robot controller, PLC, and A/D conversion PCB. The weaving pattern is taught in meticulously by manual teach. A fixture unit is also developed for dual purpose. The main aspects of the system is presented in this paper especially in the design and implementation procedure. The signal diagrams and sequence logic diagrams are also included. The outcome of the dual purpose welding cell is the increased productivity and good production stability which is indispensable for production volume prediction. Also, it leads to reduction of manufacturing lead time.

• Journal of Welding and Joining
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• v.15 no.4
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• pp.166-177
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• 1997

The high strength AlZnMgCu0.5 alloy is a light metal with good age hardenability, and has a high tensile and yielding strength. Therefore, it can be used for structures requiring high speciple strength. Even though high strength AlZnMgCu alloy has good mechanical properties, it has a lot of problems in TIG and MIG welding processes. Since lots of high heat absorption is introduced into the weldment during TIG and MIG processes, the microstructural variation and hot cracks take place in heat affected zone. Therefore, the mechanical properties of high strength AlZnMgCu0.5 alloy can be degraded in weldment and heat affected zone. Welding process utilizing high density heat source such as electron beam should be developed to reduce pore and hot cracking, whichare usually accompanied by MIG and TIG welding processes. In this work, electron beam welding process were used with or without AlMg4.5Mn as filler material to avoid the degradation of mechanical properties. Mechanical and metallurgical characteristics were also studied in electron beam weldment and heat affected zone. Moreover hot cracking mechanism was also investigated.