• Title/Summary/Keyword: Case depth

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Study on Effective Case Depth for Case Hardened Rolling Bearings (탄소 표면경화처리 구름베어링의 유효 경화 깊이에 대한 고찰)

  • Lee, Han-Young
    • Tribology and Lubricants
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    • v.32 no.1
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    • pp.18-23
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    • 2016
  • The effective case depth for case-hardened rolling bearing has been discussed. For this purpose, rolling contact fatigue tests for ball bearings built with inner race of various hardness values were conducted until L10 calculating rating life using a bearing life test machine under radial loading. Then, the distribution of residual stress below the inner raceway, which depended on the hardness value, was measured by X-ray diffraction. As a result, the linear relationship was established between the hardness value of the inner race and the theoretical shear stress evaluated at the depth where the residual stress disappeared below the inner raceway. Based on the relationship, it could be found that the factor of safety in bearing manufacturer’s rules for the effective case depth of case hardened rolling bearings was set higher. However, it could be also found that the hardness values at the depth where the maximum shearing stress acted below the raceway surface in a tapered roller bearing hardened by the carburizing process, were not sufficient for preventing plastic deformation under the basic dynamic load rating. Consequently, further efforts were still required to reduce or to disperse the contact load on the material design of a rolling bearing in order to prolong its life.

Nondestructive Measurement of Case Hardening Depth with Eddy Current Method (와전류법을 이용한 강의 표면경화층 깊이의 비파괴적 측정)

  • Lee, K.W.;Han, S.Y.;Park, U.S.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.11 no.1
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    • pp.38-43
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    • 1991
  • The relationship between eddy current response and case hardening depth has been studied on SM40C(KS D-3752) and SCM440(KS D-3711) steels which were surface hardened by high frequency induction hardening. The results obtained in this study were as follows ; 1) Case hardening depth was successfully measured by observing the eddy current impedance changes of each steel. The impedance decreased linearly with increasing case hardening depth. 2) For large impedance gradient between the hardened surface and core metal, the eddy current response was more sensitive to case hardening depth than for low impedance gradient.

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Pridiction of Case Depth in Laser Beam Hardening (레이저 표면경화에서 경화깊이 예측)

  • Kim, Jae-Do;Cho, Chong-du;Seo, Jung-Won;Cho, Yong-Moo
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.6
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    • pp.87-95
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    • 1995
  • In order to predict the case depth and case width in laser transformation hardening, a finite element method was used to analyze the temperature distribution on the material. Laser hardening of the specimens of SM45C and STE11steels was experimented by using the continuous wave CO$_{2}$ laser with the various travel speeds and the defocused Gaussian beam mode. Phosphate coating was adopted on the surface of SM45C to increase the absorption of 10.6 .mu. m laser energy. Experimental data show good agreement with the theoretical predictions. The maximum possible case depth can be predicted for the given laser hardening conditions, such as laser power, and travel speed.

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An experimental study on the in-process measurement of case depth for LASER surface hardening process (레이저 표면경화 공정에서 경화층깊이의 실시간 측정을 위한 실험적 연구)

  • Woo, H.G.;Park, Y.J.;Han, Y.H.
    • Journal of the Korean Society for Precision Engineering
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    • v.10 no.2
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    • pp.66-75
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    • 1993
  • This paper proposes a monitoring method for nondestructive and in-process measurement of the case depth in LASER surface heat treatment process. The method is essentially an eddy-current method, and measures sensing coil's electrical impedance which varies with the changes of the material microstructure due to hardening. To investigate te validity of the proposed method a series of experiments were performed for various hardning depths. The results show that the relationship between the eddy- current sensor output and the changes in case depth is almost linear. This indicates that the eddy-current measuring method can be used as one of the possible monitoring method for mesauring the hardened depth in LASER heat treatment processes.

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A Study on Fatigue Behavior according to Effective Case Depth in Induction Case Hardened SM45C Steel (고주파표면경화한 SM45C 강에서 유교경화층깊이가 피로거동에 미치는 영향)

  • 오세욱;호정원;박원조
    • Journal of Ocean Engineering and Technology
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    • v.5 no.1
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    • pp.71-80
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    • 1991
  • This paper reveals the effect of the effective case depth(ECD) on the fatigue behavior of a high-frequency induction hardened SM45C in rotated bending fatigue test. In addition, the effects of fracture modes(surface origin type, inner origin type) on it are discussed. The fatigue limit of the induction hardened steel is remarkably increased compared with that of base metal. In addition, the fatigue limit is linearly increased as the effective casedepth grows deep in the region of this experiment (ECD/R;0.23-0.49). The S-N curve and fracture mode in the induction case hardened steel are classified into two kinds, as a result : N$_{f}$<10$^{5}$ ;surface origin type fracture(at high stress), N$_{f}$>10$^{5}$ ; in ner origin type fracture(at low stress). In case of inner origin type fracture; as the effective case depth(ECD) gets deep, the fatigue limit is increased by the reason that the fracture origin moves toward center; in reverse, is decreased by reason that the compressive residual stress gets low. As a result, the increasing effect of the former is much bigger than the decreasing effect of the latter, and the fatigue limit is increased as the ECD gets deep.eep.

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Model Test on the Effect of the Depth of Revetment by Inter Sand Layer in Soft Ground (모형토조 실험을 이용한 연약지반내 중간모래층이 호안제방하부 강제치환 깊이에 미치는 영향 연구)

  • Chung, Hyung-Sik;Bang, Chang-Kuk;Lee, Yong-Jun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.956-965
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    • 2005
  • In this paper, the effect on the forced replacement depth of the revetment in soft soil with inter sand layer is analyzed by model test. In the result, the forced replacement occur in 60 second from filling the embankment material. The shape of the forced replacement depth is like to punching shape. Then, in case of thin inter sand layer and near the embankment, the forced replacement depth of inter sand layer case is more than only clayed soil case.

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Ion Nitriding Using Pulsed D.C Glow Discharge Combined with Inductively Coupled Plasma (펄스직류방전과 유도결합방전의 복합에 의한 SCM440강의 이온질화)

  • Kim, Yoon-Kee
    • Journal of the Korean institute of surface engineering
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    • v.43 no.2
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    • pp.91-96
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    • 2010
  • SCM440 steels were nitrided using pulsed dc plasma combined with inductively coupled plasma (ICP) generated by 13.56 MHz rf power in order to enhance case hardening depth. The case hardening depth was increased with rf power. The effective case-depth with ICP at 900 watt was as 1.6 times as that nitrided without ICP. The hardening depth was also increased up to 1.45 times. The compound layers formed on top surface were dense and thin when pulsed dc plasma was combined with ICP.

Effect of Prior Structure on Torsional Fatigue Strength of Induction Surface Hardened Medium Carbon Steel (고주파 표면경화된 중탄소강의 비틀림 피로강도에 미치는 초기조직의 영향)

  • Kim, Heung-Jip;Chung, In-Sang
    • Journal of the Korean Society for Heat Treatment
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    • v.11 no.4
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    • pp.247-257
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    • 1998
  • In order to evaluate the relation between prior structure and fatigue strength on a induction surface hardened medium carbon steel(SAE1050M) for automotive drive shafts, torsional fatigue test were conducted with various cases of different hardened depths and applied loads. Prior structures of the steel such as pearlite, fine pearlite and spheroidal pearlite were prepared by conventional nomalizing, tempering after quenching and spheroidized annealing, respectively. Maximum torsional fatigue strength can be obtained when the case depth is 18~25% diameter of the bar in each prior structure. The effect of case depth on the torsional fatigue strength was different depending on applied load to specimen, but the most good fatigue life was shown in the case of pearlitic structure when the case depth was 4.0~5.5mm(18~25% of bar diameter). Among three different prior structures, energy consumption, to obtain high strength or to get the same case depth, was the most saved in the case of pearlitic structure.

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Experimental Study on Seepage Losses in Earth Channel (흙 수로에 대한 삼수손실량 추정에 관한 실험적 연구)

  • 정하우;유한열
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.15 no.1
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    • pp.2853-2877
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    • 1973
  • Models of cross-sections and channels were made in order to measure seepage losses. Cross-sections were made of sand, sandy clay loam and loam, their thicknesses being 30cm and 40cm, respectively. Flow depths kept in the cross-sections were 4cm, 6cm, 8cm and 10cm. Straight and curved channel models were provided so as to measure seepage losses, when constant water depths maintained at the heads of the channels were 7.3cm and 5.7cm, respectively. The results obtained in this experiment are presented as follows: 1) A cumulative seepage loss per unit length at a point in the channel varies in accordance with time and flow depth. The general equation of cumulative seepage loss may be as follows(Ref. to Table V.25): $$q_{cum}=\int_{o}^aq(a)dt+\int_a^bq(b)dt+\int_b^tq(c)dt$$ 2) In case that the variation of water depth through the channel is slight, the total seepage loss may be computed by applying the following general equation: $$\={q}_{cum}{\cdot}x=\int_o^tq_{cum}\frac{{\partial}x}{{\partial}t}dt$$ 3) Because seepage loss varies considerably according to water depth in case that the variation of flow depth through the channel is great, seepage loss should be computed by taking account of the change of flow depth. 4) The relation between time and traveling distance of water flow may be presented as the following general equation(Ref. to Table V.29): $$x=pt^r$$ 5) The ratios of the seepage losses of the straight channel to the curved channel are 1:1.03 for a flow depth of 7.3cm and 1:1.068 for that of 5.7cm. 6) The ratios of the seepage losses occurring through the bottom to those through the inclined plane in the channel cross-section are 1:2.24 for a water depth of 8cm and 1:2.47 for a depth of 10cm in case that soil-layer is 30cm in thickness. Similarly, those ratios are 1:2.62 and 1:2.93 in case of a soil-layer thickness of 40cm(Ref. to Table V.5).

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Study on Effect of Channel Intrusion Depth on the Two-Phase Flow Distribution at Header-Channel Junction (헤더-채널 분기관의 채널 돌출길이가 2상 유동 분배에 미치는 영향에 대한 연구)

  • Lee, Jun Koung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.28 no.11
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    • pp.444-449
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    • 2016
  • The main objective of this work is to experimentally investigate the effect of angle variation and intrusion depth of channels on the distribution of two-phase flow at header-channel junctions. The dimensions of the header and the channels in cross-section were fixed at $16mm{\times}16mm$ and $12mm{\times}1.8mm$, respectively. Air and water were used as the test fluids. Two different header-channel positions were tested : a vertical header with horizontal channels (case VM-HC) and a horizontal header with horizontal channels (case HM-HC). In all cases, the intrusion depths of the channels are 0 mm, 2 mm, and 4 mm. For the case of the intrusion depth of VM-HC, the flow distribution became more uniform. However, the intrusion depth negatively affected the flow distribution for the case of HM-HC because liquid separation delay occurred.