• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.118.5-118
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• 2002

To apply induction hardening method to a press die having 3-D free surface, the induction hardening tool moves on a press die above 1～2mm gap with constant velocity. Since the induction hardening process requires its own hardening path for each die, a direct teaching method which generates working path directly guided by operators is more suitable than an offline method using CAD/CAM data. The direct teaching apparatus in this work includes a teaching tool with a force/torque sensor and data processing computer to finally generate robot's Induction hardening program , in direct teaching operation, an operator teaches working path maintaining contact with surface of press die by holding...

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.813-823
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• 2023

In this study, microstructure, hardening layer hardness, and case depth were evaluated after induction hardening(IH) of base metal specimen(BM) treated with annealing and quenching-tempering specimen(QT) treated with quenching and tempering. The microstructure after IH was significantly influenced by the microstructure before IH and the induction coil heating movement speed, but the effect of the induction frequency was very small. The hardness of the hardened layer at an induction coil heating movement speed of 15 mm/s or less was more influenced by the microstructure before IH than the induction coil travel speed and induction frequency. The induction coil travel speed has the significantly effect on the case depth, the induction frequency has effect and the microstructure before IH has a small effect.

• Journal of Ocean Engineering and Technology
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• v.23 no.2
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• pp.74-80
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• 2009

Surface hardening treatments, such as using the high-frequency induction hardening method, are widely used to increase the fatigue life and prevent the failure of materials by locally increasing the surface hardness. This method, in particular, brings an improvement in static strength by compressive residual surface stress due to the hardening. In this study, the mechanical properties of high-frequency induction hardened SCM440 steel were investigated. These results were also compared with those for base metal and a Q/T (tempering after quenching) treatment specimen. The test results showed that partially high-frequency induction hardened SCM440 steel specimens were more improved in static strength, surface hardness, fatigue limit, and anti-wear than the base metal and Q/T treatment specimens. In particular, the fatigue limit of the high-frequency induction hardened SCM440 steel increased by more than about 52% compared to that of base metal and by about 25% compared to that of the Q/T specimen.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.459-463
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• 2008

Induction hardening has been used to improve torsional strength and characteristics of wear for axle shaft which is a part of automobile to transmit driving torque from differential to wheel. After rapidly heating and cooling process of induction hardening, the shaft has residual stress and material properties change which affect allowable transmit torque. The objective of this study is to predict the distribution of residual stress and estimate the torsional strength of induction hardened axle shafts which has been residual stress using finite element analysis considered thermo mechanical behavior of material and experiments. Results indicate that the torsional strength of axle shaft depends on the surface hardening depth and distribution of residual stress.

• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.1-7
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• 2018

In this study, we proposed a high frequency induction hardening analysis method based on electromagnetic-thermal co-simulation. In the high frequency induction heating analysis, the results of the finite element analysis (FEA) (considering the change of the material property and the cooling factor according to the temperature) and those of the high frequency induction hardening experiment (using the S45C specimen) were compared. The hardness of the S45C specimens was measured using the micro Vickers hardness test to determine the depth of hardening. The measurement results were then compared with the results of FEA. The result of high frequency induction heating analysis showed that the temperature was more than $750^{\circ}C$, which is the A2 transformation point of S45C, while the temperature during quenching was below $200^{\circ}C$. The results showed that the difference of the depth of hardening between the FEA and the experiment is 0.2mm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.676-679
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• 1995

Practically, induction surface hardening is used widely to enhance the local strength of structure. In this study, Fatigue limit and its S-T characteristic for raw and induction hardened specimen of SCM440 is studied experimentally. The life prediction was considered by Juvinall's equation and its predicted result is compared with experiment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.6
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• pp.533-539
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• 2008

An high frequency induction hardening technology of vehicle body press-formed of thin sheet steel has been developed to increase the strength of vehicle body parts locally by high frequency induction heating, thereby eliminating the need for reinforcements. And this technique for increasing the tensile strength of sheet steel was practically applied to the front floor cross member and center pillar reinforcement of a passenger car. The side impact behavior has been investigated when induction hardening technology is applied to the conventional low-carbon steel and weight reduction of an automotive body is expected. In this paper, basic experiments were performed for the hat-shaped specimen under high frequency induction heating process. Martensitic transformation was found in the heating zone through microscopic observation which showed higher hardness. In addition, the hardness and strength of the center-pillar specimen made of boron steel increased remarkably by high frequency induction heating.

• Journal of the Korean Society of Safety
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• v.23 no.1
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• pp.12-17
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• 2008

The earn shaft is very important for the safety of automobiles. The earn shaft needs a surface hardening process by high frequency induction to have both strength and toughness. It is required for safety of automobile to consider how the characteristics of tensile strength and toughness are changed according to the condition of surface hardness. In this study, we prepared surface hardened SM53C which is used as cam shaft materials. We examined the tensile strengths according to the depth of surface hardening and the effect of tempering. We also investigated the fracture toughnesses according to the depth of surface hardening(1mm, 2mm).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.645-649
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• 2010

Induction hardening has been used to improve the torsional strength and characteristics of wear for axle shaft that is used to transmit driving torque from the differential to the wheel in automobiles. After the rapid heating and cooling processes of induction hardening are carried out, the shaft has residual stress and material properties change; this affects the allowable transmitted torque. The objective of this study is to predict the distribution of residual stress and estimate the torsional strength of induction-hardened axle shafts with residual stress. In this study, the finite element method is used to study the thermomechanical behavior of the material, and the results are compared with experimental results. The results indicate that the torsional strength of the axle shaft depends on the surface hardening depth and distribution of residual stress.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.130-136
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• 2005

Induction hardening increases hardness near the surface where it's most needed, and leaves the surface in compression which improves fatigue life. Although case depth and chemical composition are same, the structure of induction hardened shaft affects the fatigue strength and life because of austenization during hardening. Therefore torsional fatigue tests of specimens from various structures, which are obtained by nomalizing, spheriodized annealing and tempering after quenching, were conducted on induction hardened automotive drive shafts with various case depths and loads applied in order to evalute the relation between structure and fatigue strength.