• Journal of Welding and Joining
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• 제29권6호
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• pp.82-87
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• 2011

In this study, we conducted laser welding by using remote scanner that is 5J32 aluminum alloy to observe the mechanical properties and optimize welding process parameters. As the control factors, laser incident angle, laser power and welding speed were set and as the result of weldablility, tensile shear tests were performed. ANOVA (Analysis of Variation) was also carried out to identify the influence of process variables on tensile shear strength. Strength estimation models were suggested using regression alnalysis and 2nd order polynomial model had the best estimation performance. In addition optimal welding condition was determined in terms with wedalility and productivity using objective function and fitness function. Final optimized welding condition was laser power was 4 kW, and welding speed was 4.6 m/min.

• 소성∙가공
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• 제21권8호
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• pp.467-472
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• 2012

Shaving shear-welding is a solid-state welding process, which utilizes plastic deformation of surplus material. The solid-state nature of this process contributes to high integrity and strength of the weld. The objective of this study was to investigate the effects of process variables on the material flow patterns and identify the process condition for obtaining the best weld. FEM simulations were carried out along with experimental characterizations. The results showed the importance of the cutter angles and the overlap lengths, and helped attain the optimum shaving shear-welding die and the best process condition.

• Journal of Welding and Joining
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• 제35권2호
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• pp.35-42
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• 2017

The GMA welding process involves large number of interdependent variables which may affect product quality, productivity and cost effectiveness. The relationships between process parameters for a vertical weldment and mechanical properties are complex because a number of process parameters are involved. To make the vertical-position welding, a method that predicts bead geometry and accomplishes the desired mechanical properties of the weldment should be developed. In addition, a reliable welding process and conditions must be implemented to reduce weld structure failure. In this study, the welding process analysis of investigates the interaction between the heat input and welding parameter(Welding current, Arc voltage, Welding speed) for predicting the weldment hardness.

• 대한기계학회논문집A
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• 제24권10호
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• pp.2581-2588
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• 2000

In previous studies, the dynamic resistance, which was calculated by the process variables measured at the electrode of the welding machine, and the electrode displacement were used for quality exa mination. However, in-process usage of such systems is not effective in systems that include a welding gun attached to a robot. In order to overcome such problems, we obtained and used the process variables from the welding machine timer. This would allow us to estimate real time in -process weld quality. For quality estimation, the features were extracted as factors from the primary dynamic resistance patterns, which were measured in t he welding machine timer. The relationship between the indexes and nugget size of the welds was observed through the regression analysis. Using the analyzed factors, a regression model that could estimate nugget diameter was developed. Two regression equations of the model were suggested depending on the factors, and it was showed that the model developed by stepwise method was effective one for weld quality estimation. The developed estimation model was in good linearity with the nugget diameter obtained through the experimentation.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1992년도 특별강연 및 추계학술발표 개요집
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• pp.91-95
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• 1992

The resistance spot welding process has been extensively used for joining of sheet metals, which are subject to variation of many process variables. Many qualitive analyses of sampled process variables have been attempted to predict nugget size. In this paper, dynamic resistance and electrode movement signal which is a good indicative of the nugget size was examined by introducing an artificial neural network estimator. An artificial neural feedforward network with back-propagation of error was applied for the estimation of the nugget size. The prediction by the neural network is in good agreement with the actual nugget size for resistance spot welding of galvanized steel. The results are quite promising in that the quantitative estimation of the invisible nugget size can be achieved without conventional destructive testing of welds.

• 한국생산제조학회지
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• 제6권4호
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• pp.89-95
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• 1997

Welding technique is widely applied to general industry such as pressure vessel for chemical plant, pipe system, heavy industry, and automobile. There are some points which must be considered when robot system is used in welding automation process for productivity improvement. Welding quality is governed by heat input, and this quantity can be different according to shape, property, and thick of material . For desired heat input , weld input parameters such as welding voltage, current, and welding velocity must be determined with those consideration. Until now these parameters have been determined mainly by experience of operator. In this study, the size of welding zone was predicted by fuzzy rules were constructed from the relation between welding variables and weld pool size. Inverse model method which welding control input for welder is determined with optimum voltage and current by fuzzy controller is validatied by computer simulation.

• Journal of Welding and Joining
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• 제35권3호
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• pp.75-81
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• 2017

Recently in the welding field, the establishment of unmanned and automated systems are rapidly developing. Accurate interpretation of the welding phenomenon is applied a number of monitoring systems. In this paper, butt welding (6t) type I using Plasma-MIG welding was carried out. And we evaluated characteristics of the Al-5083 aluminium alloy in Plasma-MIG hybrid welding. Process variables including the plasma current, MIG voltage, wire feeding rate and the welding speed were used. Butt welding was conducted 1 pass. Argon gas was used as the protective gas that results from the experiment were able to achieve full penetration. In addition to monitoring the welding process occurring during MIG welding current, welding votage and Plasma current, voltage were collected in real time, the photodiode and CCD cameras observing the phenomenon that the welding is in progress were measured using a quantity of light.

• Journal of Welding and Joining
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• 제26권1호
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• pp.63-68
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• 2008

This paper has aimed to prevent excessive heat input by controlling arc distribution and heat input capacity with pulse GTAW in order to improve weld quality in 0.08mm pressure gauge diaphragm and flange welding parts. A design of experiment was designed using Box-Behnken method to optimize a welding process. The pulse GTAW parameters such as pulse current, base current, pulse duty, frequency and welding speed were set to input variables while hydraulic pressure that represents welding characteristics in diaphragm and flange joint were set to output variables. Based on the test result, a second regression equation was obtained between input and output variables and turned out significant. Besides, an influence of parameters has been confirmed through response surface analysis using the second-order regression equation and optimum welding condition was obtained through a grid-search method. The optimum welding condition was set to pulse current 84.4(A), base current 29.6(A), pulse duty 58.8(%), frequency 10(%), and welding speed 596(mm/min). Then, decent bead shape was acquired with no excessive heat input under the $2.3kgf/cm^2$ of hydrostatic pressure.

• International Journal of Korean Welding Society
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• 제2권2호
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• pp.47-50
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• 2002

Because of the environmental problems, automotive companies are trying to reduce the weight of car body. Therefore, TRIP(TRansformation Induced Plasticity) steels, which have high strength and ductility have been developed. Welding process is a complex process; therefore deciding the optimal welding conditions on the basis of experimental data is an effective method. However, trial-and-error method to decide the optimal conditions requires too many experiments. To overcome these problems, response surface methodology was used. Response surface methodology is a collection of mathematical and statistical techniques that are used in the modeling and analysis of problems in which a response of interest is influenced by several variables and the objective is to optimize this response. This method was applied to the resistance spot welding process of the TRIP steel to optimize the welding parameters.

• 소성∙가공
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• 제27권3호
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• pp.145-153
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• 2018

Magnesium material could be widely used in the automotive industry because of its high strength to weight ratio, but the electric resistance spot welding process of magnesium sheets is difficult because of its low electric resistance and high thermal conduction and thermal expansion. For this reason, an electric resistance surface friction spot welding process using rotating dies is suggested for the spot welding of magnesium metal sheets. This welding method can be characterized by three heating methods: (1) electric resistance heating on contacted surface, (2) surface friction heating by rotating dies, and (3) thermal conduction heating from heated steel electrodes, for the fusion of metal at the interfacial zone between the two magnesium sheets. This welding process also has variables to explore, such as welding currents, diameters of the steel electrode, and rotating dies. It was found that the welding strength could reach industrial requirements by applying a welding current of 11.0kA, with steel electrodes of 12mm diameter, with rotating dies of 4.4 mm diameter, under the condition of a revolution speed of 1200rpm of rotating dies, for the surface friction spot welding process of AZ31 magnesium alloy sheets of 1.4mm thickness.