• Title/Summary/Keyword: Surface roughness Direction Ratio

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Roughness and micro pit defects on surface of SUS 430 stainless steel strip in cold rolling process

  • Li, Changsheng;Zhu, Tao;Fu, Bo;Li, Youyuan
    • Advances in materials Research
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    • v.4 no.4
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    • pp.215-226
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    • 2015
  • Experiment on roughness and micro pit defects of SUS 430 ferrite stainless steel was investigated in laboratory. The relation between roughness and glossiness with reduction in height, roll surface roughness, emulsion parameters was analyzed. The surface morphology of micro pit defects was observed by SEM, and the effects of micro pit defects on rolling reduction, roll surface roughness, emulsion parameters, lubrication oil in deformation zone and work roll diameter were discussed. With the increasing of reduction ratio strip surface roughness Ra(s), Rp(s) and Rv(s) were decreasing along rolling and width direction, the drop value in rolling direction was faster than that in width direction. The roughness and glossiness were obtained under emulsion concentration 3% and 6%, temperature $55^{\circ}C$ and $63^{\circ}C$, roll surface roughness $Ra(r)=0.5{\mu}m$, $Ra(r)=0.7{\mu}m$ and $Ra(r)=1.0{\mu}m$. The glossiness was declined rapidly when the micro defects ratio was above 23%. With the pass number increasing, the micro pit defects were reduced, uneven peak was decreased and gently along rolling direction. The micro pit defects were increased with the roll surface roughness increase. The defects ratio was declined with larger gradient at pass number 1 to 3, but gentle slope at pass number 4 to 5. When work roll diameter was small, bite angle was increasing, lubrication oil in micro pit of deformation zone was decreased, micro defects were decreased, and glossiness value on the surface of strip was increased.

A Study on the Texturing Characteristics of Work Roll and Variation of Strip Surface Roughness in 4-Hi Mill (4단 압연기용 작업롤의 표면조도가공 특성과 판면조도 변화에 관한 연구)

  • Kim, Moon Kyung;Jeon, Eon Chan;Kim, Soon Kyung
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.7
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    • pp.167-175
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    • 1996
  • Work roll wear in the cold rolling of steel strip is strongly affected by rolling materials, rolling conditions and lubrication. Tests were performed to find the effects of rolling materials under the same lubricating conditions. Surface roughness of cold rolled steel strip as well as the coating technique itself is quite improtant in obtaining high image clarity of electronic products and car outer panels. Therefore this paper reviews for improvement of roughness and peak count about the surface of Cr coated work roll is investigated from the actual temper mill. The conclusions were obtained as follows; 1) Work roll wear in the cold rolling of steel strip is strongly affected by carbon contents of rolling materials, but there is not a separating force and total reduction ratio. 2) The roughness of strip surface is larger in the direction of width than in roll direction. 3) The electro-discharge textured roll has more uniform roughness distribu- tion than shot blasted roll and it's life time is two times longer than shot blasted because it has more harmonic wave roughness, and the higher peak count of surface roughness. 4) The life time of Cr coated work roll is 2 times longer than that of shot blasted work roll and variation of peak count, roughness and life time of Cr coated work roll is similar to electro-discharge texturing work roll. 5) The proper Cr coating thickness is 10 .mu. m at the work roll of temper mill.

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Study on Nickel Plating of Leadframe using Pulse Technique (펄스법을 이용한 리드프레임의 니켈도금에 관한 연구)

  • Chung W.S.;Min B.S.;Lim J.J.;Chung U.C.
    • Journal of Surface Science and Engineering
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    • v.36 no.3
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    • pp.242-250
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    • 2003
  • Electrodeposition of Ni was carried out on copper substrate from Ni Sulfamate bath by DC and high frequency pulse current. During the electroplating, bath temperature was steady $60^{\circ}C$ , agitation was applied. Morphology and surface roughness of electrodeposits was investigated with the AFM. Crystalline structure of electrodeposits was investigated with XRD. Also, surface electric resistivity was investigated with 4-point probe. The result of crystalline structure by X-ray diffractometer, in the case of DC, <200> direction was dominant growing direction. But in the case of PC, the ratio of <200> direction vs. other direction decreased. As the pulse frequency increased, the enhanced properties of deposits were shown. With increasing frequency, the degree of surface properties increased DC more than that of PC, eg surface morphology, roughness and the degree of compactness of grains. With increasing duty cycle, the surface properties such as the degree of the morphology, roughness and electroconductivity was deteriorated.

Characteristics of Fluid Supply in Discontinuous Wheel Grinding (단속연삭의 유제공급 특성)

  • Kwak, Yong-Gil;Hong, Sun-Ik;Song, Ji-Bok;Koo, Yang
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.857-861
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    • 1997
  • In discontinuous wheel grinding, temperature is different form conventional grinding. The characteristics of discontinuous grinding with respect to various slotted wheel were compared with those of general grinding. Thermal conditions vary with intermittent ratio, direction of fluid supply for discontinous wheel. According to three direction of grinding fluid supply and intermittent ratio,temperature and surface roughness were analyzed.

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A Method for Measurement of Roughness of Ground Surfaces by Using Fluxes of Scattered Lights (산란광속측정에 의한 연삭가공 표면 거칠기 측정방법)

  • Hong, Seong-Wook;Kim, Hyun-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.4
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    • pp.46-54
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    • 1995
  • This paper presents a simple method for measurenemt of roughness of ground surfaces. The present method utilizes fluxes of scattered lights condensed through lenses aligned along the specular direction. A theoretical analysis is preformed for the purpose of investigating the possibility of the method as well as determining the experimental condition. Experiments are also performed to show the effectiveness and robustness of the proposed method. The theoretical and experimental results show that the proposed method is simple enouth to implement and has a potential to identify a wide range of roughness of ground surfaces.

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Surface pressure measurements in translating tornado-like vortices

  • Kassab, Aya;Jubayer, Chowdhury;Ashrafi, Arash;Hangan, Horia
    • Wind and Structures
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    • v.33 no.6
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    • pp.447-462
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    • 2021
  • High spatial and temporal surface pressure measurements were carried out in the state-of-the-art tornado simulator, the Wind Engineering, Energy and Environment (WindEEE) Dome, to explore the characteristics of stationary and translating tornado-like vortices (TLV) for a wide range of swirl ratios (S=0.21 to 1.03). The translational speed of the TLV and the surface roughness were varied to examine their effects on tornado ground pressures, wandering, and vortex structure. It was found that wandering is more pronounced at low swirl ratios and has a substantial effect on the peak pressure magnitude for stationary TLV (error percentage ≤ 35%). A new method for removing wandering was proposed which is applicable for a wide range of swirl ratios. For translating TLV, the near-surface part lagged behind the top of the vortex, resulting in a tilt of the tornado vertical axis at higher translating speeds. Also, a veering motion of the tornado base towards the left of the direction of the translation was observed. Wandering was less pronounced for higher translation speeds. Increasing the surface roughness caused an analogous effect as lowering the swirl ratio.

A Study on the Grinding Characteristics of the Quartz (Quartz의 연삭 특성에 관한 연구)

  • Lim, Jong-Go;Ha, Sang-Baek;Kim, Sung-Hun;Choi, Hwan;Lee, Jong-Chan
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.7
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    • pp.106-111
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    • 2001
  • This study reports the grinding characteristics of quartz. Grinding experiments were performed at various grinding conditions including wheel mesh, table speed and depth of cut. The grinding forces and specific grinding energies were measured. Surface roughness was also measured with tracer and the ground surfaces were observed with SEM. A new parameter SDR(Surface roughness Direction Ratio) is proposed to characterize the grinding mechanisms of quartz. A set of experiments was performed to verify the effectiveness of the suggested parameter. The experimental results indicate that the ductile mode is the dominant material removal mode at the grinding conditions which show the higher value of SDR whereas the material is removed by brittle fracture in a lower value of SDR value increases with wheel mesh size.

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A Study on the Grinding Characteristics of the Quartz(II) (Quartz의 연삭 특성에 관한 연구 (II))

  • Lim, J. G.;Ha, S. B.;Kim, S. H.;Choi, H.;lee, J. C.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.875-879
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    • 2000
  • In the previous report1), the grinding characteristics of quartz were investigated. In this paper, the grinding mechanisms of brittle materials including ceramics and quartz are modeled and a new parameter SDR(Surface roughness Direction Ratio) is proposed to characterize the grinding mechanisms of such materials. A set of experiments were performed to verify the effectiveness of the suggested parameter. The experimental results indicate that the plastic deformation is the dominant material removal mode at the grinding conditions which show the higher value of SDR. In the case of quartz, the material was removed by brittle fracture in a lower value of SDR and by plastic deformation in a higher value of it. SDR is not affected by wheel mesh size when brittle fracture occured. But in the plastic deformation case, SDR value increases with wheel mesh size.

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Influence of Joint Secondary Roughness on Roughness Parameter in Direct Shear Test (직접전단시험에서 절리면의 2차 거칠기가 거칠기 정량화 파라미터에 미치는 영향)

  • Lee, Deok-Hwan;Choi, Sung-Oong
    • Tunnel and Underground Space
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    • v.24 no.1
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    • pp.89-96
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    • 2014
  • Rock joint surface roughness, which is known to be one of the most important factors for defining shear strength of rock mass, has been researched in various methods. However, approaches to separate a roughness into two groups (primary and secondary) for evaluating the roughness have been rarely performed. In this study, elements of secondary roughness were eliminated through direct shear testing with tensile joint specimen and they were quantified with joint parameters. It is revealed that roughness parameters decrease with increasing the normal stress and sampling intervals, except for the case in which the normal stress is larger than 1.5 MPa. Also it is analyzed that ratio of area reduction in the opposite direction of shearing decreases with increasing the roughness parameter.

Comparison of 3 Typical methods for ultra-precision grinding (가공방식에 따른 초정밀 연삭의 비교)

  • Park, Soon-Sub;Lee, Ki-Young;Kim, Hyoung-Mo;Lee, Jae-Seol
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.6 no.3
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    • pp.9-15
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    • 2007
  • Three methods for grinding: cross grinding, slanted tool axis grinding and parallel grinding, were carried out to study the machinability of tungsten carbide mold for glass formed aspherics lens. In our research, the optimum grinding conditions were investigated in terms of feed-rate, relative velocity of wheel and work piece, tool marks and surface roughness. It is shown that cross grinding are most effective in removal ratio but poor in surface roughness. In addition, tool marks of each method were differentiated on direction and shape.

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