• International Journal of Korean Welding Society
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• v.1 no.2
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• pp.7-11
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• 2001

Almost every die for automobiles must be corrected or remodeled for minor geometrical changes or fur better hardness characteristics by an arc welding process. Although many other kinds of arc welding processes have been automated with robots, the molten metal deposition process for die remodeling still depends entirely on experienced welders. In this study, a database for bead shapes with respect to welding parameters is constructed through experiments to automate molten metal deposition by the arc welding process. Changes in the welding parameters for inclined base metal are studied to consider the effect of die geometries on the welding process.

• Transactions of Materials Processing
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• v.28 no.6
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• pp.347-353
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• 2019

The porthole extrusion process is a classic metal forming process to produce complex cross-section shaped aluminum profile. It is very difficult to design porthole die and extrusion process because of the complex shape of extrusion die and internal metal flow. The main variables in this process are ram speed, initial billet and tool temperature, and die shape. In general, the metal flow of porthole extrusion process can be divided into two steps. During the first step, the billet is divided into several parts in the porthole die bridge. During the second step, the divided billets are welded in the welding chamber. In the welding chamber, the level of welding pressure is very important for the quality of the final product. The purpose of this study is to increase the welding pressure in the welding chamber by using a two stage welding chamber. The porthole extrusion die was designed by using the Taguchi method with orthogonal array. The effectiveness of the optimized porthole die was verified by using the finite element analysis.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.110-114
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• 2001

The welding pressure in porthole die extrusion is affected by the shape of welding chamber. It is very important to increase the welding pressure when the tube is used particulary as the materials of hydroforming processing. The high circumferential stress of the tube would make the welding pressure increase during the porthole die extrusion. In order to increase the circumferential stress, it is necessary to make the billets pass through the narrow gap between the conical die and the conical mandrel. This paper describes the welding pressure by the experiments with the two types of the chamber. One of them is the chamber between the flat die and straight mandrel, and the other one is the chamber between the conical die and conical mandrel. The result of the experiments show that the conical chamber makes the welding pressure increase by the effect of the reducing the diameteres of tube.

• Transactions of Materials Processing
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• v.26 no.2
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• pp.115-120
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• 2017

Porthole extrusion process is a very effective metal forming process to produce aluminum profiles with hollow sections. The structure of porthole extrusion die is very complex. In this process, the billet is divided by porthole bridge, and then the divided billet is welded in the welding chamber. The welding pressure in the welding chamber is very important. The higher welding pressure improves the quality of the aluminum profiles. Therefore, the objective of this study is to develop a new porthole extrusion die for improving the welding pressure in the welding chamber by using numerical analysis. The effectiveness of the new porthole extrusion die was verified by using numerical analysis. Through numerical analysis, the welding pressures in the welding chamber between the new porthole die and the conventional porthole die were compared with each other.

• Transactions of Materials Processing
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• v.11 no.6
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• pp.495-502
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• 2002

The welding pressure in extru bending process is affected by the shape of welding chamber of porthole die. It is very important to increase the welding pressure when the tube should be extruded particulary from four billets of the materials. The high circumferential stress of the tube can make the welding pressure increase during the extru-bending. In order to increase the circumferential stress, it is necessary to make the billets pass through the narrow gap between the conical die and the conical plug. This paper describes the welding pressure by the experiments and the analysis with the two types of the chamber. One of them is the chamber between the flat die and straight mandrel, and the other one is the chamber between the conical die and conical plug. The results of the experiments and the analysis shows that the conical chamber makes the welding pressure increase by the effect of the reducing diameter of tube and the welding pressure by the conical dic and plug is stronger than the welding pressure by the flat die and straight mandrel.

• Journal of Welding and Joining
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• v.20 no.3
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• pp.60-66
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• 2002

Almost every die fur automobiles must be corrected or remodeled for minor geometrical changes or for better hardness characteristics by arc welding process. Although many other kinds of arc welding processes have been automated with robots, this molten metal deposition process for die remodeling still depend entirely on experienced welders. In this study, the database for bead shapes with respect to welding parameters are constructed by experiments to automate the molten metal deposition by arc welding process. And the changes of welding parameters for inclined base metal are studied to consider the effect of die geometries fur the welding process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.74-77
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• 2000

Porthole die extrusion has a great advantage in the forming of hollow section tubes difficult to produce by conventional extrusion with a mandrel on the stem. Because of the complicated structure of die assembly, extrusion process as a forming of hollow section tubes has been investigated experimentally Therefore, analytic approaches that are useful in profitable die design and in the improvement of productivity are inevitably demanded Welding strength is affected by many parameters, which are such as extrusion ratio, extrusion speed, die shape, porthole number, bearing length, billet temperature and mandrel shape. In this paper, the parameters, which are such as billet temperature, bearing length and tube thickness, are examined. The welding pressures are examined through 3D simulation of non steady state and compared with experimental results.

• Journal of Power System Engineering
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• v.4 no.4
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• pp.54-58
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• 2000

The complete joining method for dissimilar hot die punch materials and its real-time evaluation method are not available at present. Brazing method has been used for joining them, but it is known that the welded joint by the brazing has the lower bonding efficiency and reliability than the diffusion welding. The friction welding with a diffusion mechanism in bonding was applied in this study. So, this work was carried out to determine the optimal friction welding conditions and to analyze mechanical properties of friction welded joints of hot die punch materials (STD61 for the blade part of hot die punch) to alloy steel (SCM440 for the shank part of hot die punch) such as plunger. In addition, acoustic emission test was carried out during friction welding to evaluate the weld quality.

• Transactions of Materials Processing
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• v.12 no.3
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• pp.214-220
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• 2003

In the case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. There have been few studies about condenser tube extruded by porthole die. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to variation of chamber length in porthole die. The welding chamber height in condenser tube was calculated by using finite element method. Forming analysis results for condenser tube would provide useful information for the optimal design of porthole die.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.66-72
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• 2003

In case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. However, there have been few studies about condenser tube extruded by porthole die. Original metal flow of condenser tube by porthole die extrusion is similar to hollow cylinder extrusion but the estimation of metal flow for extrusion parameters is different. For example, variation of chamber length in hollow extrusion only affects the welding pressure, however, the welding chamber length in condenser tube extrusion influences to the welding pressure as well as the deflection of mandrel. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to angular variation in the bottom of chamber in porthole die. Estimation was carried out using finite element method in as non-steady state. Analytical results can provide useful information the optimal design of porthole die.