• Journal of Welding and Joining
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• 제32권3호
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• pp.1-10
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• 2014

The efficient application of any welding process depends on the understanding of associated process parameters influence on the weld quality. The weld quality includes the weld bead dimensions, temperature distribution, metallurgical phases and the mechanical properties. A detailed review on the experimental and numerical approaches to understand the parametric influence of a single wire submerged arc welding (SAW) and multi-wire SAW processes on the final weld quality is reported in two parts. The first part deals with the experimental approaches which explain the parametric influence on the weld bead dimensions, metallurgical phases and the mechanical properties of the SAW weldment. Furthermore, the studies related to statistical modeling of the present welding process are also discussed. The second part deals with the numerical approaches which focus on the conduction based, and heat transfer and fluid flow analysis based studies in the present welding process. The present paper is the first part.

• 소성∙가공
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• 제26권6호
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• pp.348-355
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• 2017

In recent years, dissimilar materials such as aluminum, magnesium, titanium, and advanced high strength steel are widely used in automotive body due to environment concerns and fuel consumption. Therefore, joining technology is important for assembling components made of dissimilar materials. In this study, friction stir hole clinching (FSHC) was proposed as a new mechanical joining method to join dissimilar materials. This process stirs and heats the upper sheet, forming mechanical interlocking with the lower sheet. The feasibility of this FSHC process was verified by comparing cross-section of joint in FSHC and hole clinching process under the same processing condition. Taguchi method was also applied to the FSHC process to estimate the effect of process parameters on joint strength and obtain optimal combination of process parameters. Joint strength of FSHC with optimal process condition was compared to that of FSHC with initial process condition as well as that of hole clinching with optimal process condition. Results showed that the FSHC process was useful for joining dissimilar materials, even if the formability of materials was low.

• Journal of Welding and Joining
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• 제31권4호
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• pp.23-27
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• 2013

Laser heat source was used for automotive interior and exterior parts to reduce weights. Typically, 900's nm wavelength of laser has been widely used for polymer joining, however, the transmittance of the laser beam thorough clear polymers such as PMMA or PC has been an issue to overcome. To solve this issue, 1,940nm laser was applied on the clear polymer for the better absorption and 900nm laser beam was used for main laser for the joining. Conventional Gaussian or Elliptical heat source approximation has limitation in polymer which had deeper skin depth where major laser beam absorbs. To accurately simulate the physical laser beam absorption and joining optical properties were experimentally measured for the computer FEM simulation. The simulation results showed close correlation between theoretical and experimental results. The developed laser process is expected to increase productivity and gap closing which can cause failure of joining in laser material processing.

• 한국기계가공학회지
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• 제21권2호
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• pp.87-93
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• 2022

The demand for metal-polymer joining technology have been increasing, especially in the industrial fields of automotive and aerospace, which require the manufacturing of various lightweight parts. Conventional joining processes have technical hurdles on aspects such as thermal degradation, need for chemical surface treatment, or complicated process settings. These issues can be alleviated by employing interlocking structures for the metal-polymer joined interface. In this study, we joined 3D-printed metal and polymer parts, which were featured with 3D-printed interlocking structures at their interface. By using high frequency induction heating, the joined region could be locally heated to reduce the thermal degradation and distortion of polymer parts. In addition, through the adjustment of interface morphologies and compression conditions, the polymer flow could be optimized to completely fill the interlocking grooves on metal parts, thereby achieving high joining strength. This suggests feasible guidelines for manufacturing metal-polymer joined structures involving 3D-printed architectures.

• Journal of Welding and Joining
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• 제24권6호
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• pp.28-32
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• 2006

Laser Transmission Joining (LTJ), which is a joining process of polymers by using different transmission rates of materials, was studied numerically. Unlike previous studies, energy loss by reflection at the surface was included. Besides, energy absorbed in the transparent substrate is also considered to increase the accuracy of the analytical results. Furthermore, thermal deformations of the substrates were also calculated. Temperature distribution of the substrates on the joining process could be effectively predicted by using the thermal analysis model developed, which could also analyze the rising phenomenon of the absorbing substrate by bulge effect. Calculated results show that temperature of the absorbing substrate is higher than that of transparent substrate when the laser is being radiated, and this temperature difference causes more thermal deformation in absorbing substrate, which results in the surface rise of the absorbing substrate. Comparison of calculated results with corresponding experimental results could confirm the validity of the numerical analysis model proposed.

• Journal of Welding and Joining
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• 제23권5호
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• pp.25-29
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• 2005

Steel has been mainly used in the automotive industry, because of good mechanical properties, weldability and so on. However, there has been increase in using aluminum to reduce the weight of vehicle. This leads to improve fuel efficiency and to reduce air pollution. A steel-aluminum hybrid body structure is recently used not only to reduce the weight of vehicle but also to increase safety. In this paper, the laser beam joining method is suggested to join steel and aluminum. To avoid making brittle intermetallic compounds(IMC) that reduce mechanical properties of the joint area, only aluminum is melted by laser irradiation and wetted on the steel surface. The brittle IMC layer is formed with small thickness at the interface between steel and aluminum. By controlling the process parameters, brittle IMC layer thickness is suppressed under 10 micrometers which is a criterion to maintain good mechanical properties.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.282-288
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• 2002

A new on-line bar joining technology employing the concept of a solid-state joining has been developed for the endless rolling by POSCO, RIST and MHMM Inc.. In the process, the bars are partially descaled, partially overlapped, joined by shearing action and crops are finally removed. The feasibility of the developed process was evaluated in this study in terms of microstructures and mechanical properties of joints, and the response of the joint to rolling.

• 소성∙가공
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• 제13권4호
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• pp.342-349
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• 2004

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. The joining strength from the process ranges 50-70 percent of that of the resistance spot welding. In this paper, a new form-joining process with the aid of an adhesive is proposed in which an epoxy adhesive is applied to a sheet metal pair, and before it cures the pair is clinched to cause the geometric constraint in the form of a protrusion. In order to reduce the forming load and the height of protrusions, a new die and punch set with a very small clearance is devised to reduce the depth of drawing and the forming load. Taguchi method is employed to find the optimal values of design parameters. To implement each case of the orthogonal array, the finite element method is used. The experiments show that in the tensile-shear test, the bonding strength of the new form-joining process with an epoxy adhesive is approximately the same as that of the resistance spot welding; and in comparison with the other two form-joining processes with an epoxy adhesive, the height of protrusions is reduced by more than 65 percent and the forming load by 50 percent.

• Journal of Welding and Joining
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• 제25권2호
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• pp.43-48
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• 2007

Laser Transmission Joining (LTJ) of plastics is a process in which light of suitable wavelength is transmitted through a transparent substrate that is in contact with an absorbing one. In this paper, LTJ is investigated by preliminary experiments from the viewpoint of mechanical engineering. To understand transmitting characteristics of each polymer substrate, transmission rate, reflection rate and absorption coefficient of polymer are measured by using a laser power-meter. Characteristics of joining in the spot welding and seam welding are investigated by measuring the fracture load. Fracture load increases in accordance to the laser power and irradiation time. However, when the laser power is over 60W and irradiation time over 4seconds, fracture load decreases. This phenomenon is probably due to heat-softening of materials. Besides, cavities are generated at a joint by evaporation of water molecules, which can be suppressed by introduction of a gap between two substrates.

• Journal of Welding and Joining
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• 제30권6호
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• pp.49-55
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• 2012

The tandem welding process is one of the most efficient welding processes widely used in material joining technique such as manufacturing of strong and durable structures. It facilitates high rate of joint filling with little increase in the overall rate of heat input due to the simultaneous deposition from two electrode wires. The two electrodes in tandem welding process helps in high-efficiency and high productive of welding process. In this study a automated tandem welding system is developed to determine the correlation between cathode and anode and compared with current ratio of the two electrode torch. Three different inter-electrode distances were chosen, 25mm, 35mm and 45mm to perform the experiment with three different current ratio. From the experiment results, the current ratio between two torch has a large impact on width, height and depth of penetration. In addition, a stable bead geometry is obtained when inter-electrode distance is 35mm.