• International Journal of Precision Engineering and Manufacturing
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• v.4 no.2
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• pp.30-38
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• 2003

This paper proposed PID controller for torch slider and PD controller for motor right wheel. to control the motion of two-wheeled welding mobile robot with seam tracking sensor touched on welding line. The motion control is realized in the view of keeping constant welding velocity and precise seam tracking even though the target welding line is on straight line or curved line. The position and direction of the body of the mottle robot are controlled by using signal errors between seam tracking sensor and body positioning sensor attached on the end of torch slider and body side of the mobile robot, respectively. In turning motion, the body and the torch slider are controlled by using the kinematic model related with two motions of body turning and torch sliding. The straight locomotion is controlled according to eleven control patterns obtained from displacements between two sensors of the seam tracking sensor and the body positioning sensor. The effectiveness is proven through the experimental results fur lattice type welding line. Through the experimental results, we can see that the position value of the electrode end point and the welding velocity are controlled almost constantly both in straight and turning locomotion.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.66-76
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• 2002

Automated welding and soldering are an important manufacturing issue in order to lower the cost, increase the quality, and avoid labor problems. An off-line programming, OLP, is one of the powerful methods to solve this kind of diversity problem. Unless an OLP system is ready for the path optimization in welding and soldering, the waste of time and cost is unavoidable due to inefficient paths in welding and soldering processes. Therefore, this study attempts to obtain path optimization using a genetic algorithm based on artificial intelligences. The problem of welding path optimization is defined as a conventional TSP (traveling salesman problem), but still paths have to go through welding lines. An improved genetic algorithm was suggested and the problem was formulated as a TSP problem considering the both end points of each welding line read from database files, and then the transit problem of welding line was solved using the improved suggested genetic algorithm.

• Journal of Welding and Joining
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• v.24 no.5
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• pp.62-66
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• 2006

Panel line is an important process occupying the largest work amount in shipbuilding. In this research product simulation has been carried out to establish the optimal production scheduling. For this purpose a web-based panel line simulator was developed using an object modeling technology and C# language. The balance of work-load and increase in the productivity by the improvement of production facilities and process are the key factors for a good scheduling. In this study SPRT(Shortest Remaining Process Time) rule was applied for the work-load balancing and a good result achieved. To increase the productivity in the stiffener welding stage which is a bottleneck; process, more welding heads and higher welding speed were tested using the developed simulator. The simulation results showed that either more welding head or higher welding speed decreased the total work time. Use of both, however, deteriorated the productivity because of the bottleneck in the following stage. This result points out that the improvement of production facilities and/or process should be evaluated with their influences on the leading and following processing stage.

• Transactions of Materials Processing
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• v.9 no.5
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• pp.453-462
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• 2000

Tailor-welded blanks are used for forming of automobile structural skin components. The main objective of this study is to achieve weight and cost reduction in manufacturing of components. For successful application of tailor-welded blanks, design of initial welded blanks and prediction of the welding line movement are critical. The utilization of the backward tracing scheme of the finite element method shows to be desirable in design of initial welded blanks for net-shape production and in prediction of the welding line movement. First the design of the initial blank in forming of welded thick sheet with isotropy is tried, and it appears successful in obtaining a net-shape stamping product. Based on the first trial approach, the backward tracing scheme is applied to anisotropic tailored blanks. The welding line movement is also discussed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.339-344
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• 1999

For the Tailor Welded Blank sheet used for automobile body panel, the characteristics of fatigue strength and crack propagation behavior were studied. The thickness of specimen was machined to be same (0.9mm+0.9mm) and different (0.9mm+2.0mm). As a base test, mechanical properties around welding zone were examined. The results indicated that there were no significant decreases in mechanical properties, but hardness around welding bead is 2.3 times greater than base material. The fatigue strength was the highest when the loading direction was parallel to the welding direction, which was about 85% of tensile strength of base material. It was decreased by 8.5% when the thickness of specimen and base material was different, and it is increased by 25% when pre-strain was applied. The crack propagation rate was noticeable decreased around welding line and rapidly increased as it passed by welding line. Reviewing the shape of the crack propagation, crack width around welding line was wide around the welding zone due to retardation of crack growth, but it became narrow passing welding line due to decreased toughness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.719-723
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• 1997

The welding automation in ship manufacturing process,especially in the sub-assembly line is considered to be a difficult job because the welding part is too huge, various, unstructured for a welding robot to weld fully automatically. The weld orocess at the sub-assembly line for ship manufacturing is to joint the various stiffener on the base panel. In order to realize automatic robot weld in sub-assembly line, robot have to equip with the sensing system to recognize the position of the parts. In this research,we developed a vision system to detect the position of base panle for sub-assembly line is shipbuilding process. The vision system is composed of one CCD camera attached on the base of robot, 2-500W halogen lamps for active illumination. In the image processing algorithm,the base panel is represented by two set of lines located at its two corner through hough transform. However, the various noise line caused by highlight,scratches and stiffener,roller in conveyor, and so on is contained in the captured image, this nosie can be eliminated by region segmentation and threshold in hough transform domain. The matching process to recognize the position of weld panel is executed by finding patterns in the Hough transformed domain. The sets of experiments performed in the sub-assembly line show the effectiveness of the proposed algorithm.

• Journal of Welding and Joining
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• v.25 no.6
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• pp.64-70
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• 2007

Recently, several models to control weld quality, productivity and weld properties in arc welding process have been developed and applied. Also, the applied model to make effective use of the robotic GMA(Gas Metal Arc) welding process should be given a high degree of confidence in predicting the bead dimensions to accomplish the desired mechanical properties of the weldment. In this study, a development of the on-line learning neural network models that investigate interrelationships between welding parameters and bead width as well as apply for the on-line quality control system for the robotic GMA welding process has been carried out. The developed models showed an excellent predicted results comparing with the predicted ability using off-line learning neural network. Also, the system will extend to other welding process and the rule-based expert system which can be incorporated with integration of an optimized system for the robotic welding system.

• Journal of Ocean Engineering and Technology
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• v.16 no.1
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• pp.64-70
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• 2002

This paper shows the results of the development of a small size of digital type continuous and intermittent welding auto-carriage based on microprocessor (Intel 80196KC) for welding process with long welding line. The developed welding auto-carriage loads welding torch and tracks welding line. It is an automaton largely used for welding process with a lot of long welding lines such as shipbuilding and structure. Most traditional auto-carriages have been developed based on analog circuit for open loop control. So this analog circuit welding auto-carriage cannon control welding speed. Specially welding auto-carriage for intermittent welding condition is so complicated and has the low precision of control performance in welding distance and non-welding distance. The auto-carriage developed in this paper has the following characteristics: It has not only functions of traditional carriage but also functions such as pseudo-welding process of big iron structures, intermittent welding in order to limit heat for welding thin plates, crater treatment of the final step of welding, acceleration at the initial step of welding and deceleration in the final step of welding. The main control board of auto-carriage, power supply system and DC motor drive wee developed and manufactured. The welding speed and the welding distance of the developed auto-carriage are controlled accurately by feedback control using photo-sensor. Hardware and software robust against the heat and noise produced on the welding process are developed.

• Proceedings of the KWS Conference
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• 2003.05a
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• pp.155-158
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• 2003

Orbital GTA welding is used in the pressure pipe line of auto-mobile, LNG and plant piping. To weld the pipe line safely, to some extent, the back bead must be formed in the root pass. In the plate welding the back bead can be observed, but in the pipe welding, the back bead can not be observed directly. In the welding around circumference, the parameters such as gravity, surface tension and arc force are different at each position. And then D/B for welding condition at each position are required. We also studied about the setting of the optimum orbital welding condition by controlling heat input.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1752-1756
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• 2003

Welding automation in shipbuilding process, especially in the assembly line is considered to be a difficult job because welding part is too huge , various and unstructured for a welding robot to weld the whole part automatically. We developed an automatic welding robot to improve those difficult process. This paper show how to systematically operate the integrated automation system which consists of several robots. We introduce our software and system integration method. Specially we focus that network communication and operating process. The developed system visualizes the operation environment using Open Inventor and communicates with the entire system via TCP/IP and FTP.