• Title/Summary/Keyword: machining load

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A Study on the Precision Hole Machiningof Pre Hardened Mould Steel (프리하든 금형강의 정밀 홀 가공에 관한 연구)

  • Lee, Seung-Chul;Cho, Gyu-Jae;Park, Jong-Nam
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.11 no.2
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    • pp.98-104
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    • 2012
  • In this paper, precision processing is carried out for the pre hardened steel(HRC 54), which is one of injection mould materials. Processing characteristics are estimated according to the number of tool cutting blade and roundness is observed by the 3-Dimensional measuring machine. The surface roughness affected by the wire electric discharge machining are measured. Cutting component force of STAVOX is the highest in condition of 2F processing because load per a blade of cutting tool is high. Especially, the difference in Fz is over 20N by cutting load. The slower spindle rotation speed and tool feed rate are, the better cutting component force is. The roundness of hole processed in condition of 4F is good because feed rate is able to be fast. When rotation speed is increased, the surface roughness is decreased. The surface roughness acquired in condition of 2F processing is higher about 50% than 4F processing.

A Load Balancing Problem in a Parallel Machine Shop Considering Operator Sharing (작업자 공유가 가능한 병렬기계작업장에서 작업자 부하 균형을 고려한 작업할당문제)

  • Moon, Dug-Hee;Kim, Dae-Kyoung
    • IE interfaces
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    • v.12 no.2
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    • pp.166-173
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    • 1999
  • In this paper, a load balancing problem among operators is considered, when one or more identical machines can be assigned to an operator. The operations of a job are separated into three categories : machine-controlled elements, operator-controlled elements and machine/operator-controlled elements. Machining or forming operations are included into the first category. The second category includes inspection and moving to another machine, and the last category includes setup and loading/unloading operation. The objective is to balance the workloads among operators under the constraints of available machine-time and operator-time. A hierarchical heuristic solution procedure is suggested for allocating jobs to each machine and allocating machines to each operator. The performance of the algorithm is evaluated with various data set.

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Forming of Metallic Bipolar Plates by Dynamic Loading (Dynamic Load를 이용한 박막 금속 분리판 성형기술)

  • Koo, J.Y.;Kang, C.G.
    • Transactions of Materials Processing
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    • v.21 no.1
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    • pp.5-12
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    • 2012
  • The weight of the bipolar plate is one of the crucial aspects of improving power density in PEMFC stacks. Aluminum alloys have good mechanical properties such as density, electrical resistivity, and thermal conductivity. Furthermore, using aluminum in a bipolar plate instead of graphite reduces the bipolar plate cost and makes machining easier. Therefore in this study, an aluminum alloy was selected as the appropriate material for a bipolar plate. Results from feasibility experiments with the aim of developing fuel cells consisting of Al bipolar plates with multiple channels are presented. Dynamic loading was applied and the formability of micro channels was estimated as a function of punch pressure and die radius. Sheets of Al5052 with a thickness of 0.3mm were used. For a die radius of 0.1mm the formability was optimized with a sine wave dynamic load of 90kN at maximum pressure and 5 cycles of a sine wave punch travel. The experimental results demonstrate the feasibility of the proposed manufacturing technique for producing bipolar plates.

Remaining Life Estimation of a Level Luffing Crane Component by Computer Simulation (컴퓨터 시뮬레이션을 통한 수평 인입 크레인 구성 재료의 잔존수명 예측)

  • Kim, Sangyeol;Kim, Seongsoo;Choi, Heekyu
    • Korean Journal of Metals and Materials
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    • v.48 no.6
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    • pp.489-497
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    • 2010
  • The remaining life estimation of the level luffing crane component, which has operated for about 20 years is examined carefully, especially on the crane structures. To analyse the crane sructures, the basic load and load combination needed to be considered. We modeled various parts of the level luffing crane to analyse fatigue. Fatigue analysis results showed that the level luffing crane is in the fatigue life so that the crane is in the safe state in fatigue cumulative damage. Analysis results show that the remaining life of a jib upper beam would be about 10 years therefore, the level luffing crane should be stable for fatigue for that period.

A Study on Nano/micro Pattern Fabrication of Metals by Using Mechanical Machining and Selective Deposition Technique (기계적 가공과 무전해 선택적 증착기술을 이용한 나노/마이크로 금속패턴 제작에 관한 연구)

  • Cho S.H.;Youn S.W.;Kang C.G.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1507-1510
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    • 2005
  • This study was carried out as a part of the research on the development of a maskless and electroless process for fabricating metal micro/nanostructures by using a nanoindenter and an electroless deposition technique. $2-\mu{m}-deep$ indentation tests on Ni and Cu samples were performed. The elastic recovery of the Ni and Cu was 9.30% and 9.53% of the maximum penetration depth, respectively. The hardness and the elastic modulus were 1.56 GPa and 120 GPa for Ni and 1.49 GPa and 100 GPa for Cu. The effect of single-point diamond machining conditions such as the Berkovich tip orientation (0, 45, and $90^{\circ}$) and the normal load (0.1, 0.3, 0.5, 1, 3, and 5 mN), on both the deformation behavior and the morphology of cutting traces (such as width and depth) was investigated by constant-load scratch tests. The tip orientation had a significant influence on the coefficient of friction, which varied from 0.52-0.66 for Ni and from 0.46-0.61 for Cu. The crisscross-pattern sample showed that the tip orientation strongly affects the surface quality of the machined area during scratching. A selective deposition of Cu at the pit-like defect on a p-type Si(111) surface was also investigated. Preferential deposition of the Cu occurred at the surface defect sites of silicon wafers, indicating that those defect sites act as active sites for the deposition reaction. The shape of the Cu-deposited area was almost the same as that of the residual stress field.

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A Study on the Development and Surface Roughness of Roller Cam SCM415 by 5-Axis Machining (5축 가공에 의한 SCM415 롤러 캠 개발과 표면조도 연구)

  • Kim, Jin Su;Lee, Dong Seop;Kang, Seong Ki
    • Journal of the Korean Society for Precision Engineering
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    • v.30 no.4
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    • pp.397-402
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    • 2013
  • In this study, we carried out the each lines of section, using GC (green silicon carbide) whetstone, the SCM415 material which separated by after and before heat treatments process, in 3+2 axis machining centers for integrated grinding after cutting end mill works, the spindle speed 8000 rpm and feed rate 150 mm/min. For the analysis of the centerline average roughness (Ra), we measured by 10 steps stages. Using Finite element analysis, we found the result of the load analysis effect of the assembly parts, when applied the 11 kg's load on both side of the ATC (Automatic tool change) arm. The result is as follows. For the centerline average roughness (Ra) in the non-heat treatment work pieces, are appeared the most favorable in the tenth section are $0.510{\mu}m$, that were shown in the near the straight line section which is the smallest deformation of curve. In addition, the bad surface roughness appears on the path is to long by changing angle, the more inclined depth of cut, because the chip discharging is not smoothly.

A Study on Nano/Micro Pattern Fabrication of Metals by Using Mechanical Machining and Selective Deposition Technique (기계적 가공과 무전해 선택적 증착기술을 이용한 나노/마이크로 금속패턴 제작에 관한 연구)

  • Cho Sang-Hyun;Youn Sung-Won;Kang Chung-Gil
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.8 s.185
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    • pp.171-177
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    • 2006
  • This study was performed as a part of the research on the development of a maskless and electroless process for fabricating metal micro/nanostructures by using a nanoindenter and an electroless deposition technique. $2-{\mu}m$-deep indentation tests on Ni and Cu samples were performed. The elastic recovery of the Ni and Cu was 9.30% and 9.53% of the maximum penetration depth, respectively. The hardness and the elastic modulus were 1.56 GPa and 120 GPa for Ni and 1.51 GPa and 104 GPa for Cu. The effect of single-point diamond machining conditions such as the Berkovich tip orientation (0, 45, and $90^{\circ}$ ) and the normal load (0.1, 0.3, 0.5, 1, 3, and 5 mN), on both the deformation behavior and the morphology of cutting traces (such as width and depth) was investigated by constant-load scratch tests. The tip orientation had a significant influence on the coefficient of friction, which varied from 0.52-0.66 for Ni and from 0.46- 0.61 for Cu. The crisscross-pattern sample showed that the tip orientation strongly affects the surface quality of the machined are a during scratching. A selective deposition of Cu at the pit-like defect on a p-type Si(111) surface was also investigated. Preferential deposition of the Cu occurred at the surface defect sites of silicon wafers, indicating that those defect sites act as active sites for the deposition reaction. The shape of the Cu-deposited area was almost the same as that of the residual stress field.

An Analysis of Closed Die Forging of Laser Printer Shaft by Finite Element Method (레이저 프린터용 샤프트 밀폐단조 성형해석)

  • Cho, S.H.;Shin, M.S.;Kim, J.H.;Ra, S.W.;Kim, J.B.
    • Transactions of Materials Processing
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    • v.18 no.2
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    • pp.150-155
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    • 2009
  • A shaft for laser printers has to be produced with high dimensional accuracy of a few micrometers. Most companies produce the shaft, therefore, by machining. These days, forging process is tried to be employed in manufacturing the shaft for productivity. In this study, the dimensional inaccuracy of straightness is studied and the underfill is not focused because the shaft shape is simple and the load capacity of press is sufficient. The straightness and concentricity of the shaft is important for the operation of a laser printer. Many design parameters such as preform shapes, tooling dimensions, forging load, and billet geometries may affect on the dimensional accuracy. In the forging process of shafts, a billet which is cut from wires is used. The billet, therefore, may be a little bit curved but not always straight. The elastic recovery is considered to cause the dimensional inaccuracy. Therefore, the effect of the forging load on the elastic recovery and straightness is investigated through the finite element analyses using DEFORM-3D and ABAQUS.

Maskless Pattern Fabrication on Si (100) Surface by Using Nano Indenter with KOH Wet Etching (나노인덴터와 KOH 습식 식각 기술을 병용한 Si(100) 표면의 마스크리스 패턴 제작 기술)

  • 윤성원;신용래;강충길
    • Transactions of Materials Processing
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    • v.12 no.7
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    • pp.640-646
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    • 2003
  • The nanoprobe based on lithography, mainly represented by SPM based technologies, has been recognized as potential application to fabricate the surface nanostructures because of its operational versatility and simplicity. The objective of the work is to suggest new mastless pattern fabrication technique using the combination of machining by nanoindenter and KOH wet etching. The scratch option of the nanoindenter is a very promising method for obtaining nanometer scale features on a large size specimen because it has a very wide working area and load range. Sample line patterns were machined on a silicon surface, which has a native oxide on it, by constant load scratch (CLS) of the Nanoindenter with a Berkovich diamond tip, and they were etched in KOH solutions to investigate chemical characteristics of the machined silicon surface. After the etching process, the convex structure was made because of masking effect of the affected layer generated by nano-scratch. On the basis of this fact, some line patterns with convex structures were fabricated. Achieved patterns can be used as a mold that will be used for mass production processes such as nanoimprint or PDMS molding process. All morphological data of scratch traces were scanned using atomic force microscope (AFM).

An Analysis of the Thermal Deformation of the Main Spindle for Small and Precision Lathe (소형 정밀 선반용 주축의 열 변형 해석)

  • Jian, Jin;Ko, Tae-Jo;Kim, Hee-Sool
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.6 no.1
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    • pp.43-49
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    • 2007
  • Multi-function and miniaturization of the medical equipment and tele-communication systems need small and high precision machined parts. For the economic machining of the small size workpiece it should be machined by small and high precision machine tools with high speed machining. The belt type driving system in turning lathe has a limitation of spindle speeds because of the vibrations from driving mechanism, built-in type of driving mechanism is used to reduce the vibration. However, the main spindle of the built-in motor is connected directly to the motor, so the heat generation of the motor and bearing makes bad influence of the accuracy of machine tools. In this study, the analysis of heat generation from motor and bearings supporting main spindle and experiment were carried out. The results of theoretical simulation of temperature and deformation of the main spindle are good agreement with those of measured.

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