• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.29-32
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• 2002

The mechanical joining process of a sheet metal pair has been developed in order to replace the resistance spot welding process in case that joining of mechanically unweldable materials and coated sheet metals with different thickness are needed. Form-joining or clinching, a kind of mechanical joining process, is defined as joining process of a sheet metal pair by geometric constraint imposed by plastic deformation of workpieces without any additive part. It has been reported that the joining strength by commercial form-joining apparatus is 50∼70 percent of that by resistance spot welding. Therefore, a two-step form-joining process with a secondary punch is proposed. The device is designed to improve the joining strength by increasing the geometric constraint of the deformed shape by combining a primary punch, a secondary punch and a female die. In order to verify the improved joining strength by the designed process, the tensile-shear strength, the peel-tension strength and the asymmetric peel-tension strength are compared with those by the TOX process and resistance spot welding.

• Transactions of Materials Processing
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• v.16 no.2 s.92
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• pp.107-112
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• 2007

In this study, the mechanical joining process for double sheet metals was investigated by using physical modeling method. Process parameters of mechanical joining such as friction coefficient, drawing depth, pouch radius, die radius and material thickness are preliminarily analyzed by finite element method. Referring to the finite element analysis results mechanical joining system is designed on the basis of physical similarities. From the physical modeling test, the effect of process parameters on the deformation for the mechanical joining are experimentally investigated and optimized joining shape that can provide strong joining strength is obtained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.752-760
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• 2000

Mechanical press joining has been used in sheet metal joining processes because of its simple process and possibility of joining dissimilar metals, such as steel and aluminum. The strength of mechanical press joining varies with joining conditions. The optimum joining conditions considering tensile-shear and peel-tension strength have to be established to assure the reliability in the joining strength. Therefore, optimization of joining conditions has been investigated for improving joining strength of sheet metal. It is possible to obtain optimum strength from improvement on the joining strength of peel-tension mechanical press joint under multiaxial stress states.

• Journal of Welding and Joining
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• v.33 no.3
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• pp.12-18
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• 2015

The ultimate goal of developing body is revealed the "lightweight" at latest EuroCarBody conference 2012 and the most core technology is joining process to make lightweight car body design. Accordingly, in this study, the car body assembly line for the assembly process applies to any introduction, particularly in the assembly of aluminum alloy and composite materials applied by the process for the introductory approached. Process were largely classified by welding (laser, arc, resistance, and friction stir welding), bonding (epoxy bonding) and mechanical fastening (FDS, SPR, Bolting and clinching). Applications for each process issues in the case and the applicable award was presented, based on the absolute strength of the test specimens and joining characteristics for comparative analysis were summarized. Finally, through this paper, we would tried to establish the characteristics of the joint for lightweight structure.

• Journal of Welding and Joining
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• v.32 no.4
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• pp.20-25
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• 2014

Laser heat source was applied on 3D poly urethane model built by 3D printer and cellulous acetate for joining. A diode laser with 808nm wavelength was transmitted through the 3D model and applied on the boundary of ABS/Acetate and 3D poly urethane model. Based on the experimental result, the ABS and 3D built poly-urethane polymers was successfully joined, but the mechanical strength was not enough at the joining boundaries in the range of 6watt to 8watt of laser heat source. However, biodegradable acetate was successfully joined without damaging the 3D built model and mechanical strength was properly achieved. The optimum laser power was found between 5watt and 8watt with scanning speed of 500mm/min, 700mm/min and 1,000mm/min. Based on the SEM analysis the filling mechanism was that the applied pressure on 3D built model squeezed the fluidic thermoplastics, ABS and acetate, into the structure of 3D model. Therefore soundness of joining was strongly depending on the viscosity of thermoplastics in polymers. The developed laser process is expected to increase productivity and minimize the cost for the final products.

• Journal of Welding and Joining
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• v.32 no.5
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• pp.50-57
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• 2014

Friction Stir Welding (FSW) is a complex process with several mutually interdependent parameters. A slight difference from known settings may lead to imperfections in the stirred zone. These inhomogeneities affect on the mechanical properties of the FSWed joints. In order to prevent the failure of the welded joint it is necessary to detect the most critical defects non-destructive. Especially critical defects are wormhole and lack of penetration (LOP), because of the difficulty of detection. Online thermography is used process-accompanying for defect detecting. A thermographic camera with a fixed position relating to the welding tool measures the heating-up and the cool down of the welding process. Lap joints with sound weld seam surfaces are manufactured and monitored. Different methods of evaluation of heat distribution and intensity profiles are introduced. It can be demonstrated, that it is possible to detect wormhole and lack of penetration as well as surface defects by analyzing the welding and the cooling process of friction stir welding by passive online thermography measurement. Effects of these defects on mechanical properties are shown by tensile testing.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.1-6
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• 2011

New methods for joining sheet of metal are being sought. One of the most promising methods is MPJ (mechanical press joining). It has been used in thin metal work because of its simple process and relative advantages over other methods, as it requires no fasteners such as bolts or rivets, consumes less energy than welding, and produces less ecological problems than adhesive methods. In this study, the joining process and static behavior of single overlap joints has been investigated. During fixed die type joining process for SPCC plates, the optimal applied punching force was found. The maximum tensile-shear strength of the specimen produced at the optimal punching force was 1.75 kN. The FEM analysis result on the tensile-shear specimen showed the maximum von-Mises stress of 373 MPa under the applied load of 1.7 kN, which is very close to the maximum tensile strength of the SPCC sheet(= 382 MPa). This suggests that the FEM analysis is capable of predicting the maximum tensile load of the joint.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.53-60
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• 2014

The automatic arc welding is generally accepted as the preferred joining technique and commonly chosen for assembly of large metal structures such as in areas of automotive, aircraft and shipbuilding due to its joint strength, reliability, and low cost compared to other joint processes. Recently, several mathematical models have been developed and studied for control and monitoring welding quality, productivity, microstructure and weld properties in arc welding processes. This study indicates the prediction of process parameters for the expected welding quality with accordance to the adaptive GTA welding process. Furthermore, the mathematical models is also develop to aid the selection of an optimal welding process as the generation of process controls to predict the bead geometry as a function output parameters in the GTA welding process. The developed models through this study showed comparatively excellent predicted results, and will extend to other welding processes to integrate an optimized system for the robotic welding process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.131-135
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• 2003

The form-joining process (or clinching) uses a set of die and punch to impose the plastic deformation-induced geometric constraint on a sheet metal pair, But their joining strength ranges 50-70 percent of that of the resistance spot welding. In this paper, a new form-joining process with the aid of adhesive is proposed in which an epoxy adhesive is applied to a sheet metal pair, to improve joining strength. The strength and mechanical properties of the new process are discussed and compared for other joining processes.

• Journal of Welding and Joining
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• v.34 no.2
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• pp.54-58
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• 2016

SPR(Self-Piercing rivet) is mechanical element of joining sheet metal components without the need for pre-punched or pre-drilled holes. Newly designed SPR is developed for high joining strength and shearing strength than semi-tubular rivet. In this study, divided shank of self-piercing rivet were designed for joining DP440 and SILAFONT. Newly designed SPR was simulated by using FEM code DEFORM-3D. In simulations of SPR process, various shape of self-piercing rivet were considered for semi-tubular and newly designed SPR. In other to examine the joinability, joining load and lap-shear load of newly designed SPR were compared with semi-tubular by simulated results and experimental ones.