• Journal of Welding and Joining
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• v.18 no.5
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• pp.63-69
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• 2000

A genetic algorithm was applied to an arc welding process to determine near optimal settings of welding process parameters which produce good weld quality. This method searches for optimal settings of welding parameters through systematic experiments without a model between input and output variables. It has an advantage of being able to find optimal conditions with a fewer number of experiments than conventional full factorial design. A genetic algorithm was applied to optimization of weld bead geometry. In the optimization problem, the input variables was wire feed rate, welding voltage, and welding speed and the output variables were bead height, bead width, and penetration. The number of level for each input variable is 16, 16, and 8, respectively. Therefore, according to the conventional full factorial design, in order to find the optimal welding conditions, 2048 experiments must be performed. The genetic algorithm, however, found the near optimal welding conditions from less than 40 experiments.

• International Journal of Korean Welding Society
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• v.1 no.1
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• pp.44-50
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• 2001

A genetic algorithm was applied to the arc welding process as to determine the near-optimal settings of welding process parameters that produce the good weld quality. This method searches for optimal settings of welding parameters through the systematic experiments without the need for a model between the input and output variables. It has an advantage of being capable to find the optimal conditions with a fewer number of experiments rather than conventional full factorial designs. A genetic algorithm was applied to the optimization of the weld bead geometry. In the optimization problem, the input variables were wire feed rate, welding voltage, and welding speed. The output variables were the bead height bead width, and penetration. The number of levels for each input variable is 16, 16, and 8, respectively. Therefore, according to the conventional full factorial design, in order to find the optimal welding conditions,2048 experiments must be performed. The genetic algorithm, however, found the near optimal welding conditions in less than 40 experiments.

• KSBB Journal
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• v.7 no.2
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• pp.144-148
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• 1992

The purpose of this study is to develop a continuous process for sorbitol production using dried Zymomonas mobilis immobilized in K-carrageenan. The methods of glularaldehyde cross-linking of enzymes in CTAB (celyltrimetylammoniumbromide) treated cells immobilized in K-carrageenan showed stability for the production of sorbitol for 30 days of operation. K-carrageenan beads entrapping permeabilized cells were dried to Improve bead rigidity and storage stability. A semi-batch process with dry beads was carried out and only a small loss of enzyme activity (less than 8%) was observed during 72h. The value of Vmax for the dry K-carrageenan beads was found to be one half or that for free cells. It was shown that the productivities of the continuous process with wet K-carrageenan beads and dry beads at a dilution rate 0.1h-1 were 3.4g/L-h and 2.88h/L-h, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.160-163
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• 1993

In this paper, design of an automatic grinding robot system for car brazing bead is introduced. Car roof and side panels are joined using brazing, and then the brazing bead is processed so that the bead is invisible after painting. Up to now the grinding process is accomplished manually. The difficulties in automation of the grinding process are induced by variation of position and shape of the bead and non-uniformity of the grinding area due to surface deformation. For each car, the grinding area including the brazing bead is sensed and then modeled using a 2-D optical sensor system. Using these model data, the position and the direction of discrete points on the car, body surface are obtained to produce grinding path for a 6 degrees of freedom grinding robot. During the process, it is necessary to sense the reaction forces continuously to prepare for the unexpected circumstances. In addition, to meet the line cycle time it is necessary to reduce the required time in sensing, signal processing, modeling, path planning and data transfer by utilizing real-time communication of the information. The key technique in the communication and integration of the complex information is obtaining in-field reliability. This automatic grinding robot system may be regarded as a jump in the intelligent robot processing technique.

• Journal of Welding and Joining
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• v.14 no.4
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• pp.33-42
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• 1996

In recent years there has been a significant growth in the use of the automated and/or robotic welding system, carried out as a means of improving productivity and quality, reducing product costs and removing the operator from tedious and potentially hazardous environments. One of the major difficulties with the automated and/or robotic welding process is the inherent lack of mathematical models for determination of suitable welding process parameters. Partial-penetration, single-pass bead-on-plate welds were fabricated in 12mm AS 1204 mild steel flats employing five different welding process parameters. The experimental results were used to develop three empirical equations: curvilinear; polynomial; and linear equations. The results were also employed to find the best mathematical equation under weld bend width to assist in the process control algorithms for the Gas Metal Arc Welding(GMAW) process and to correlate welding process parameters with weld bead width of bead-on-plates deposited. With the help of a standard statistical package program. SAS, multipe regression analysis was undertaken for investigating and modeling the GMAW process, and significance test techniques were applied for the interpretation of the experimental data.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.8
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• pp.42-51
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• 2021

Investigations of process parameters are essential when fabricating high-quality parts using additive manufacturing. This study investigates the change in the mechanical characteristics of a SUS316L specimen fabricated using selective laser melting based on the energy density and bead overlap ratio. The SUS316L powder particles were spherical and 35 ㎛ in size. Single-bead and hexahedral shape deposition experiments were performed sequentially. A single bead experiment was performed to obtain the bead overlap ratios for different laser parameters utilizing laser power and scan speed as experimental parameters. A hexahedral shape deposition experiment was also performed to observe the difference in mechanical properties, such as the internal porosity, surface roughness, and hardness, based on the energy density and bead overlap ratio of the three-dimensional printed part. Laser power, scan speed, overlap ratio, and layer thickness were chosen as parameters for the hexahedral shape deposition experiment. Accordingly, the energy density applied for three-dimensional printing, and the experimental parameters were calculated, and the energy density and bead overlap ratio for fabricating parts with good properties have been suggested.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.239-242
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• 2005

In the roll forming, a flat strip is progressively deformed by feeding it through a series of rotating rolls. There are various layouts for the tube toll-forming stages. The process sequences are as follows: leveling, roll-forming, welding, bead removing, seam annealing, cooling, sizing and cutting. Electric resistance welded(ERW) tubes have been widely used for the machinery parts, especially for hydroformed automotive parts. However conventional ERW tubes do not have a high formability because of hardening of welded portion by rapid cooling. Moreover the decrease in thickness of the welded portion during the grinding of the inner and outer bead may reduce the formability of the tube. In case of applying the tubular parts without grinding the bead, the flow of the fluid can be prevented due to the turbulent flow induced by the inner bead. In attempt to determine the optimal bead grinding amount in the roll forming process, in the present paper, the effects of the removal depth and width of the inner beads on the hydroformability are analyzed by the finite element simulation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.71-78
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• 2007

There have been continuous efforts to automate welding processes. This automation process could be said to fall into two categories, weld seam tracking and weld quality evaluation. Recently, the attempts to achieve these two functions simultaneously are on the increase. For the study presented in this paper, a vision sensor is made, and using this, the 3 dimensional geometry of the bead is measured in real time. For the application in welding, which is the characteristic of nonlinear process, a fuzzy controller is designed. And with this, an adaptive control system is proposed which acquires the bead height and the coordinates of the point on the bead along the horizontal fillet joint, performs seam tracking with those data, and also at the same time, controls the bead geometry to a uniform shape. A communication system, which enables the communication with the industrial robot, is designed to control the bead geometry and to track the weld seam. Experiments are made with varied offset angles from the pre-taught weld path, and they showed the adaptive system works favorable results.

• Journal of Welding and Joining
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• v.17 no.6
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• pp.46-52
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• 1999

The auxiliary gas-shielded MAG (AMAG) process, which was devised to provide an argon-rich shielding environment using small amount of argon gas, was investigated experimentally to figure out its effects on metal transfer and weld quality. Proper conditions for the AMAG process including the argon gas ratio, position and direction of the auxiliary nozzle were determined experimentally. Performance of the AMAG process was compared with that of the double gas-shielded MAG(DMAG) and MAG processes by monitoring the bead profile, current and voltage waveforms. The AMAG process was found to provide better bead profile, more stable arc and wider operating range of spray transfer mode compared with the DMAG process. In general, performance of the AMAG process using the argon ratio of 30% was comparable to that of the MAG process using 80% argon and 20% CO₂ gas.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.672-678
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• 1993

The bead shape in high frequency electric resistance (HER) pipe welding gives important information ons judging current welding state. In most manufacturing process, the heat input is controlled by skilled operators observing color and bead shape. We proposed the bead shape monitoring system in HERW pipe process by using structured light beam. We reconstructs 3-D shape of bead from the measured data, and compare this shape with real 3-D shape obtained by coordinate-measuring machine. This experiment results show that the proposed system can monitor the bead shape with good accuracy.