• Title/Summary/Keyword: Forming grinding

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Mirror Surface Grinding Using Ultrafine Grit Wheel (초미립 숫돌에 의한 경면연삭)

  • Jeong, H.D.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.6
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    • pp.45-51
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    • 1996
  • Silicon wafers are required to be finished under the roughness of nanometer order for the subsequent chip fabrication processes. Recently, the finish grinding techniques have been researched for the improvement of accuracy and surface roughness simultaneously. Among them, the grinding technique using fine abrasive has been known as an easily accessible method. However, the manufacture of the fine grit grinding wheel has been very difficult because of the coherence of the grits. In this paper, the development of the ultrafine grit silica($SiO_2$) grinding wheel by the combination of the binder coating and the vacuum forming techniques is reported. And, the mechanochemical removal effects of the grinding conditions are discussed. Finally, a successful result of Ra O.4nm. Rmax 4nm in the ground surface roughness of a 6 inch silicon wafer was achieved.

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The effects of the grinding depth of the inner bead on the steel tube hydroformability (강관의 내면비드 제거 깊이가 하이드로포밍 성형성에 미치는 영향도 분석)

  • Kim B. J.;Park K. S.;Kim D. H.;Moon Y. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.239-242
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    • 2005
  • In the roll forming, a flat strip is progressively deformed by feeding it through a series of rotating rolls. There are various layouts for the tube toll-forming stages. The process sequences are as follows: leveling, roll-forming, welding, bead removing, seam annealing, cooling, sizing and cutting. Electric resistance welded(ERW) tubes have been widely used for the machinery parts, especially for hydroformed automotive parts. However conventional ERW tubes do not have a high formability because of hardening of welded portion by rapid cooling. Moreover the decrease in thickness of the welded portion during the grinding of the inner and outer bead may reduce the formability of the tube. In case of applying the tubular parts without grinding the bead, the flow of the fluid can be prevented due to the turbulent flow induced by the inner bead. In attempt to determine the optimal bead grinding amount in the roll forming process, in the present paper, the effects of the removal depth and width of the inner beads on the hydroformability are analyzed by the finite element simulation.

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A Study on the Development of Diamond Grinding Wheel with Multi-Porous Structure (다기공 다이아몬드 연삭숫돌의 개발에 관한 연구)

    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.7 no.2
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    • pp.100-107
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    • 1998
  • Diamond wheels with fine grains and multi-porous structures are newely trial developed for smoothing and mirror finishing materials. Grinding wheel must have performed both to remove tool marks efficienitly and to contact elastically with curved surfaces, that are employed for ultra precision and high performance grinding of difficult-to materials such as tungsten carbide alloy using tool and die materials, Diamond grains are bonded by a melamine resin to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures are developed to increase the flexibility of the grinding wheel, and to induce self-sharpening by increasing contact pressure between the grinding wheel and workpiece surfaces. In this paper, melamine-bonded diamond wheels try to manufacture, then the forming method of grinding wheel are suggested, and the grinding characteristics of melamine-bonded diamond grinding wheel are also illustrated.

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A Study on Grinding Wheel Manufacture and Assessment for Application in Weaving Machine (방직산업용 연삭숫돌 제작 및 성능평가에 관한 연구)

  • Kim, Chang-Rok
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.3
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    • pp.19-27
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    • 2011
  • A weaving machine for texture industry uses a lot of needles and the nib of these needles is necessary to be kept with sharp edge. The re-grinding of the needle by a special purpose of the grinding wheel can be selected for achieving this aim. This study focused on the manufacture and performance assessment the special grinding wheel. A forming mold for the grinding wheel was designed and a sintering process for furnace process control was established. Manufactured wheels were tested for determining suitable grade of the wheel. The selection of optimal grinding conditions was achieved by a response surface method and a genetic algorithm.

A Study on Structural Safety of Integrated Machine for Grinding Wheel Forming (연삭 휠 형상 복합가공시스템의 구조 안전성에 관한 연구)

  • Lee, Won-Suk;An, Beom-Sang;Kim, Jin-Hyeon;Lee, Jong-Chan;Woo, Bong-Geun;Lee, Young-Sik
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.15 no.2
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    • pp.84-88
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    • 2016
  • This study evaluated the structural safety of a heavy-duty integrated machine for grinding wheel forming. Structural analysis was performed to evaluate the structural safety of the base. The base was designed by dividing the single base and detachable base. The analysis conditions were applied to the own weight and the load of component parts. From the structural analysis results, although the stress of the detachable base was decreased, the amount of deformation was increased. If the deformation of the detachable base decreases, it is expected to be safer than the single base.

A study on the Beneficiation for Magnesite by the Grinding Characteristic of Rock Forming Minerals (조암광물의 분쇄특성을 이용한 마그네사이트 정제기술 연구)

  • Kim, Sang-Bae;Park, Hyung-Kyu;Kim, Wan-Tae;Kim, Yun-Jong
    • Korean Journal of Materials Research
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    • v.17 no.11
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    • pp.606-611
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    • 2007
  • This study was conducted to beneficiation of magnesite by dry grinding and air classification. The raw ore was ground in a ball mill and pin mill controlled with grinding time and linear velocity of grinding media and fractionated in an air classifier. Pin mill is more efficient than the ball mill for liberation. As a result, the MgO grade of concentrate was 47.1% with recovery of 51.51% for classified with 3,000rpm of air classifier for ground at 13,000rpm in pin mill.

Preparation of Seaweed Calcium Microparticles by Wet-grinding Process and their Particle Size Distribution Analysis (초미세습식분쇄공정의 공정변수에 따른 해조칼슘의 입자크기 분석)

  • Han, Min-Woo;Youn, Kwang-Sup
    • Food Engineering Progress
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    • v.13 no.4
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    • pp.269-274
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    • 2009
  • The main objective of this study was to establish optimum condition of wet grinding process for manufacturing microparticulated seaweed calcium. Process parameters such as concentration of forming agent, rotor speed, bead size, feed rate, and grinding time were adapted during wet-grinding of seaweed calcium. The particle size range of the raw seaweed calcium was 10-20 $\mu$m. The calcium particles were reduced to under 1 $\mu$m as nano scale after grinding. Gum arabic was suitable for forming agent and 5%(w/v) concentration was the most effective in grinding efficiency. A wet-grinding process operated at 4,000 rpm rotor speed, 0,4 mm bead size, and 0.4 L/hr feeding rate, respectively, produced less than 600 mm(>>90%)-sized particles. In batch systems, 8 cycles of grinding showed higher efficiency, but 20 min of grinding time in continuous processing was more efficient to reduce particle size than the batch processing. Based on the result, the optimum conditions of the wet grinding process were established: operation time of 20 minutes, rotor speed of 4,000 rpm, bead size of 0.4 mm, feed rate of 40 mL/min and 30% mixing ration with water. The size of the resulting ultra fine calcium particles ranged between 40 and 660 mm.

Influences of the Addition of Hydride-Forming Elements and Oxide and Hydriding-Dehydriding Cycling on the Hydriding and Dehydriding Characteristics of Mg

  • Song, Myoung Youp;Kwak, Young Jun;Park, Hye Ryoung
    • Korean Journal of Metals and Materials
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    • v.50 no.5
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    • pp.375-381
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    • 2012
  • Magnesium prepared by mechanical grinding under $H_2$ (reactive mechanical grinding) with transition elements or oxides showed relatively high hydriding and dehydriding rates when the content of additives was about 20 wt%. Ni was chosen as a transition element to be added. $Fe_2O_3$ was selected as an oxide to be added. Ti was also selected since it was considered to increase the hydriding and dehydriding rates by forming Ti hydride. A sample $Mg-14Ni-3Fe_2O_3-3Ti$ was prepared by reactive mechanical grinding, and its hydrogen storage properties were examined. This sample absorbs 4.02 wt% H for 5 min, and 4.15 wt% H for 10 min, and 4.42 wt% H for 60 min at n = 2. It desorbs 2.46 wt% H for 10 min, 3.98 wt% H for 30 min, and 4.20 wt% H for 60 min at n = 2. The effects of the Ni, $3Fe_2O_3$, and Ti addition, and hydriding-dehydriding cycling were discussed.

A study on material selection for semiconductor die parts and on their modification and manufacture (반도체금형에서 부속부품의 재료선정 및 개선과 제작에 관한 연구)

  • Kim, Sei-hwan;Choi, Kye-kwang
    • Design & Manufacturing
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    • v.8 no.1
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    • pp.27-30
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    • 2014
  • Alloy tool steel such as SKD11 and SKD61 or high speed tool like SKH51 are used as materials for semiconductor dies. Cavities, curl blocks, pot blocks and housings are made from those materials. To make those parts from alloy tool steel or high speed tool, one utilizes discharge machining, and mechanical machining including machining center, milling, drilling, forming grinding and others. In the process of cutting machining and polishing, the die materials become unsuitable for machining owing to bubbles and foreign substances in them, which hinders production process. Therefore, this study focuses on die material selection criteria, and on analysis and comparison of material characteristics to help companies to solve their problems, make die manufacture less burdensome and extend die life.

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Finite Element Analysis of Glass Lens Forming Process Using Open Die (개방형 금형을 이용한 유리 렌즈 성형 해석)

  • 나진욱;임성한;전병희;오수익
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.143-147
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    • 2003
  • Despite of outstanding optical performance of glass lens, glass lens have not been widely used because of poor productivity and high cost due to manufacturing process i.e. grinding, polishing. However, press-forming method of glass lens overcomes this disadvantage because of mass production. When glass lens is produced by press-forming method using closed die, it is needed that the volume of glass lens preform precisely measured in order to prevent incomplete products and to increase in life of die. The present paper shows the shortcoming of forming process with closed die, and performs FEM simulation of forming process with open die in order to overcome this shortcoming. The design parameter of open die is selected in standard of assembly with optical module and maintenance of optical performance. FEM simulation is carried out with selected parameter of open die and two basic preform. According to distribution of effective strain in glass lens, optical property of glass lens formed at each set of die and preform is compared.

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