• Journal of Aerospace System Engineering
• /
• v.12 no.5
• /
• pp.1-7
• /
• 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
• /
• 2010.05a
• /
• pp.575-576
• /
• 2010

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.2
• /
• pp.207-212
• /
• 2016

High-frequency induction hardening (HFIH) is used in many industries and has a number of advantages, including reliability and repeatability. It is a non-contact method of providing energy-efficient heat in the minimum amount of time without using a flame. Recently, HFIH has been actively studied using the finite-element method (FEM), however, these studies only focused on the accuracy of the analysis. In this paper, we analyzed HFIH by using a variable frequency based on the conditions of the same shape and input power then comparing the analysis results to experimental results. The analysis and experimental results indicate that the hardening depths are approximately the same using the optimal frequency of 3kHz.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.1089-1092
• /
• 2001

In the stereolithography process, build parameters are laser power, scan velocity, scan width, bean diameter, layer thickness and so on. These values are determined according to product accuracy and build time. Build time can be reduced by improving of scan velocity, laser power, layer thickness, hatching space and so on. But variation of these parameters influence part accuracy, surface roughness, strength. This paper observed cure properties in various beam diameter. In order to examine these, relationships of scan velocity and cure depth, scan velocity and cure width according to various beam diameter in one scan line are measured. And cure thickness is measured according to beam diameter and scan velocity in scan surface of one layer. For reduction of build time, beam diameter and scan velocity is proposed in stereolithography process.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.3
• /
• pp.529-539
• /
• 1994

In laser heat treatment process of steels, the thin layer of substrate is rapidly heated to the austenitizing temperature and subsequently cooled at a very fast rate due to the self-quenching effect. Consequently, it is transformed to martensitic structure which has low magnetic permeability. This observation facilitates the use of a sensor measuring the change of electromagnetic field induced by the hardening layer. In this paper, the eddy-current electromagnetic field is analyzed by a finite element method. The purpose of this analysis is to investigate how the electrical impedance of the sensor's sensing coil varies with the change in permeability. To achieve this, a numerical model is formulated, taking into consideration the hardening depth, distance of the sensor from the hardened surface and the frequency driving the sensor. The results obtained by numerical simulation show that the eddy-current measurement method can feasibly be used to measure the changing hardening depth within the frequency range from 10 kHz to 50 kHz.

• Journal of Welding and Joining
• /
• v.14 no.2
• /
• pp.10-18
• /
• 1996

Al합금과 경합을 하는 경량재료에는 금속재료로서는 Mg 및 Ti이 있는데, 이들 은 고가라는 단점이 있다. 또 비금속재료로는 플라스틱.수지등이 있는데, 산업폐기물 등의 문제가 있으나, Al합금은 재활용이 용이하다. 그러나 구조재료로서의 Al합금의 특성에는 아직 많은 결점을 가지고 있으며, 가장 큰 결점의 하나는 철강재료에 비하여 내마모성이 현저하게 떨어진다는 것이다. 그러므로 이 점이 개선된다면, Al합금은 경량구조용 재료로서 다양한 분야에서 철강재료를 대신할 수 있을 것으로 전망된다. Al합금에 대한 내마모특성을 부여하기 위한 종래의 표면경화기술로서는, 고경도합금 의 채용, 알루마이드처리등이 있는데, 충분한 경도가 얻어지지 않거나, 또는 고경도가 얻어져도 경화층의 깊이가 마이크론단위에 불과하여 고하중하에서의 내마모특성 등에 대한 문제가 있었다. 이들 방법 이외에도 PVD, CVD, 도금 등에 의한 표면피복 방법과 표면의 합금화에 의한 표면경화법 등에 있어서 여러 방법들이 있으나, 경도가 높고 또한 후막의 경화층으로서 박리의 위험이 적은 표면경화처리기술은 확립되어 있지 않다고 할 수 있다. 따라서, 이 분야에 대한 기술개발이 산업계로부터 강하게 요구되 고 있으며, 또한 이것과 관련된 연구가 활발하게 진행되고 있다. 본 해설에서는. 내마 모특성에 따른 Al후막기술의 현상과 그 대표적인 기술로서, 표면용융에 의한 합금화 를 이용하는 표면경화기술에 대하여 소개한다.

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

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.212-217
• /
• 1993

In this paper, the hardening depth in Laser surface hardening process is estimated using a multilayered neural network. Input data of the neural network are surface temperature of five points, power and travelling speed of Laser beam. A FDM(finite difference method) is used for modeling the Laser surface hardening process. This model is used to obtain the network's training data sample and to evaluate the performance of the neural network estimator. The simulational results showed that the proposed scheme can be used to estimate the hardening depth on real time.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2007.11a
• /
• pp.159-160
• /
• 2007

저온 플라즈마 침탄 처리 후 연속적인 공정으로 저온 플라즈마 질화를 실시하여 내식성과 표면경도를 향상시키는 처리에서 질화처리 시 Ar 가스가 표면특성에 미치는 영향을 조사 하였다. 모든 시편의 경도가 미처리재 보다 약4배 증가하였으며, Ar가스의 양이 증가할수록 N의 침투깊이가 깊어졌다. 전체 경화증의 두께는 거의 일정하였고, 경화층은 모재보다 내식성이 증가되어 단면조직사진에서 밝게 나타났다.

• Korean Journal of Materials Research
• /
• v.3 no.5
• /
• pp.538-545
• /
• 1993

By using propagation characteristics of ultrasonic surface wave, the depth of the surface hardened layer of SCM440 steel with different high frequency induction heat treatments was measured and the same was done on the carburized SCM415 steel. The propagation velocity of surface wave was constant and independent of frequency in t.he specimens with identical microstructure, it was, however, decreased by 59m/s in the hardened layers compared to the unhardened part. From t.he relationship between the effective case depth and the wave length of surface wave, the depth of the hardened layer could be measured and evaluated nondestructively for both induction hardened and carburized steels.