• Title/Summary/Keyword: Section shape

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Effects of cutter runout on cutting forces during up-endmilling of Inconel718 (Inconel 718 상향 엔드밀링시 절삭력에 미치는 공구형상오차)

  • 이영문;양승한;장승일;백승기;김선일
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2002.04a
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    • pp.302-307
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    • 2002
  • In end milling process, the undeformed chip section area and cutting forces vary periodically with phase change of the tool. However, the real undeformed chip section area deviates from the geometrically ideal one owing to cutter runout and tool shape error. In this study, a method of estimating the real undeformed chip section area which reflects cutter runout and tool shape error was presented during up-end milling of Inconel 718 using measured cutting forces. The specific cutting resistance, K. and $K_t$ are defined as the radial and tangential cutting forces divided by the modified chip section area. Both of $K_r$, and $K_t$ values become smaller as the helix angle increases from $30^\circ$ to $40^\circ$ Whereas they become larder as the helix angle increases from $40^\circ$ to $50^\circ$. On the other hand, the $K_r$, and $K_t$ values show a tendency to decrease with increase of the modified chip section area and this tendency becomes distinct with smaller helix angle.

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Effects of Cutter Runout on End Milling Forces I-Up Eng Milling- (엔드밀링 절삭력에 미치는 공구형상오차 I- 상향 엔드밀링 -)

  • Lee, Yeong-Mun;Yang, Seung-Han;Song, Tae-Seong;Gwon, O-Jin;Baek, Seung-Gi
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.8
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    • pp.63-70
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    • 2002
  • In end milling process, the undeformed chip section area and cutting forces vary periodically with phase change of the tool. However the real undeformed chip section area deviates from the geometrically ideal one owing to cutter runout and tool shape error. In this study, a method of estimating the real undeformed chip section area which reflects cutter runout and tool shape error was presented in up end milling process using measured cutting forces. The average specific cutting resistance, Ka is defined as the main cutting force component divided by the modified chip section area. Ka value becomes smaller as the helix angle increases from $30^circC \;to\;40\circC$. But it becomes larger as the helix angle increases from $40^\circ$to 50 . On one hand, the Ka value shows a tendency to decrease with increase of the modified chip section area and this tendency becomes distinct with smaller helix angle.

A Study of the Extrusion Process of Circular Section Products with Helical Fins by Rotating Extrusion Dies (회전압출다이를 이용한 헬리컬 핀붙이 원형단면 압출가공에 관한 연구)

  • Park S. M.;Jin I. T.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2004.05a
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    • pp.31-34
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    • 2004
  • A new extrusion process of the circular section product with helical fins could be developed by using rotating extrusion dies. The twisting of extruded product is caused by the twisted conical die surface connecting the die entrance section and the die exit section linearly. But, until now, because the process has used fixed extrusion dies, it needs high pressure in order to twist billet and form fin shape on the surface of billet. So, during extruding billet, in order not to twist billet, the extrusion dies is needed to rotate itself instead of twisting billet. And in order to rotate dies, the shape of inside contour of extrusion dies must have conical type with twisted Inclined die surface connecting the die entrance section and the die exit section linearly. The results of experiments show that, in spite of using twisted extrusion dies, twisting of the billet should not happen because of rotating dies in the opposite direction of twisting direction of billet during extruding billet, and, from the results, it shows that it can decrease the power of extrusion pressure and could prevent crack of teeth for fin forming.

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Effects of Cutter Runout on Cutting Forces in Up-endmilling of Inconel 718 (Inconel 718 상향 엔드밀링시 절삭력에 미치는 공구형상오차의 영향)

  • 이영문;양승한;장승일;백승기;김선일;이동식
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.5
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    • pp.45-52
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    • 2002
  • In an end milling process, the undeformed chip section area and cutting forces vary periodically with the phase change of the tool. However, the real undeformed chip section area deviates from the geometrically ideal one owing to the cutter runout and tool shape error. In the current study, a method of estimating the real undeformed chip section area which reflects the cutter runout and tool shape error is presented during up-end milling processes of Inconel 718. The specific cutting forces, $K_r$ and $K_t$ are defined as the radial and tangential cutting forces divided by the modified chip section area, respectively. Both of the $K_{r}$ and $K_t$ values become smaller as the helix angle increases from $30^{\circ}$ to $40^{\circ}$. Whereas they become larger as the helix angle increases from $40^{\circ}$ to $50^{\circ}$. The $K_r$ and $K_t$ values show a tendency to decrease with increase of the modified chip section area.a.

Intake Performance Characteristics according to S-duct Cross-section Shape in UAV (무인기 S형 흡기구의 단면 형상에 따른 흡기구 성능 특성)

  • Eom, Hee-Ok;Bae, Ji-Yeul;Lee, Namkyu;Kim, Jihyuk;Nam, Juyeong;Jo, Hana;Cho, Hyung Hee
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.5
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    • pp.107-114
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    • 2019
  • In many military aircraft, s-shaped diffusers are used to prevent the fan blades of the turbofan engine from being exposed to the outside. The inlet configurations of the air intakes for military aircraft vary, such as the rectangular intake of the F-22, the crescent-like intake of the F-16, elliptical intake of the MQ-25. In this study, the aerodynamic performance of s-shaped diffusers with various inlet configurations was evaluated using numerical analysis. In addition, the configuration of the middle section of an s-shape duct was changed to the crescent shape, and the effects on its aerodynamic performance were investigated. As a result, there was a slight difference in total pressure recovery according to various inlet configurations with ellipse-shaped middle sections. Also, the total pressure distortion was the lowest in the rectangular inlet shape. When the configuration of the middle section was changed from an ellipse to a crescent shape, the total pressure recovery remained at a high level, except for the ellipse-shaped inlet configuration. In terms of total pressure distortion, the duct with the crescent-shaped middle section showed a significantly more uniform pressure distribution than that with the ellipse-shaped middle section.

Analysis of the Shape of Gathered Skirts using a Three-Dimensional Measurement System (3차원 계측시스템을 이용한 개더스커트 형상 분석)

  • Jung Hee-Kyeong;Lee Myung-Hee
    • Journal of the Korean Society of Clothing and Textiles
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    • v.29 no.11
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    • pp.1399-1409
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    • 2005
  • The purpose of this study was to analyze the shape of gathered skirts using a three-dimensional measurement system. And in this experiment, I try to accumulate three-dimensional data of wearing model and to figure out analyzing method made by shape of clothes. The experimental design consists of two factorial designs. I set up three different kinds of fabrics, ratio of gathers. Therefore nine samples were made. The instrument and tools for three-dimensional measurement was whole body 3D scanner. Analysis program used in experiment is RapidForm 2004 PP1 and Pattern Design 2000. Data analysis utilizes SPSS WIN 10.0 Package. T-test to effect an inspection of evidence, there was difference about measurement times. One-way ANOVA to analysis effect of gather made by gathering conditions. The following results were obtained; 1. As a result of inspecting an error several times using a three-dimension measurement system, convinced data was obtained. 2. At front, distribution of gap amount was larger than back. And as ratio of gathers increased, distribution of gap amount showed regularly. 3. After analyzing horizontal sectional figure of skirts, as a height of skirt changed from waist to the bottom of skirts, the results showed as follows. While section width, section thickness, node width, node depth increased, node count decreased. 4. With the horizontal section levels of gather skirt, the silhouette on middle hip section was similar with the silhouette of body line. And as ratio of gathers around hip section increased, nodes showed regularly. At the bottom of skirts showed different nodes by different gathering condition.

The Analysis of H-Shape Rolling by the Finite Element Method (유한요소법에 의한 H형강 압연공정의 해석)

  • 신현우;김낙수;박종진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.5
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    • pp.1095-1105
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    • 1993
  • Shape rolling processes to produce H-section beams are numerically simulated by the simplified three-dimensional finite element method. The 2-dimensional finite element method, used for the generalized plane strain condition, is combined with the slab method. Computer simulation results of the 19-passes in H-section beam rolling in practice include the grid distortions, the cross-sectional area changes, the roll separating forces, and the roll torques. Also, the amount of side spread can be found during the multi-pass rolling simulations. The finite element mesh system is remeshed with I-DEAS whenever the billet distorts severely. This study would contribute to CAD/CAM of shape rolling process through the optimal roll pass schedule.

An Experimental Study in Rectangular High Strength Concrete Columns under Both Axial Load and Biaxial Bending (2축 편심 축하중을 받는 직사각형 고강도 RC기둥의 거동에 대한 실험적연구)

  • 이종원;조문희;한경돈;유석형;반병열;신성우
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.11a
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    • pp.209-214
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    • 2001
  • Most reinforce concrete Columns of Building structure are subjected to both axial load and biaxial bending. However, It is hard to estimate the moment capacity of biaxial bending by exact solution. Thus, columns under biaxial bending are designed by approximate methods in practice. The purpose of this study is to compare experimental result with approximate methods and exact solution by computer. Parameters of the present test are compressive strength of concrete (350, 585, 650kgf/$\textrm{cm}^2$) and shape ratio of rectangular section. Ultimately, an experimental shape factor for rectangular RC column section is obtained through the test program. The shape of load contour is dominated by this shape factor obtained experimentally. So, reasonable design of RC columns subjected to both axial compression and biaxial bending depends on load contour.

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SHAPE OPTIMIZATION OF UCAV FOR AERODYNAMIC PERFORMANCE IMPROVEMENT AND RADAR CROSS SECTION REDUCTION (공력 향상과 RCS 감소를 고려한 무인 전투기의 형상 최적설계)

  • Jo, Y.M.;Choi, S.I.
    • Journal of computational fluids engineering
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    • v.17 no.4
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    • pp.56-68
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    • 2012
  • Nowadays, Unmanned Combat Air Vehicle(UCAV) has become an important aircraft system for the national defense. For its efficiency and survivability, shape optimization of UCAV is an essential part of its design process. In this paper, shape optimization of UCAV was processed for aerodynamic performance improvement and Radar Cross Section(RCS) reduction using Multi Objective Genetic Algorithm(MOGA). Lift and induced drag, friction drag, RCS were calculated using panel method, boundary layer theory, Physical Optics(PO) approximation respectively. In particular, calculation applied Radar Absorbing Material(RAM) was performed for the additional RCS reduction. Results are indicated that shape optimization is performed well for improving aerodynamic performance, reducing RCS. Further study will be performed with higher fidelity tools and consider other design segments including structure.

A Study on the Use and Features of Bangyeon on the Seungtap (방연(方椽)이 표현된 승탑의 용례와 특징에 관한 연구)

  • Cho, Hyun-Jung;Kim, Wang-Jik
    • Journal of architectural history
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    • v.26 no.2
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    • pp.7-14
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    • 2017
  • Rafter is a member for roof and plays a role in protecting shaft members under rafter such as pillar, beam and girder from natural environment and to fix by supporting finished materials of roof. It is common in the Korean architecture that rafter cross-section is paired with circular form and Buyeon cross-section is paired with the square shape. However, while there are not many, some architectures have rafter end header in the square shape. The aim of this study is to examine the square shape cases of rafter end header with special reference to stone structure. As a result, among stone structure related to Bangyeon, the majority case is seen at Palgakwondang type Seungtap. It was shown in the Seungtap of monk of Gusanseonmun school in the later Unified Silla to the early Goryeo period that succeeded Seodang Jijang.