• 제목/요약/키워드: Bending

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보일러 튜브 자동벤딩 생산시스템 개발 (Auto-Bending Manufacturing System for Boiler Tubes)

  • 이현수;강문현;박준곤;허관;성준석;허왕순
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1997년도 춘계학술대회 논문집
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    • pp.450-454
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    • 1997
  • This system is the automatic boiler tube bending equipment which has four heads for bending the tube and the carriage for moving the tube. The system consists of two frames for transporting each moving parts, high-frequency heating equipment for heating the tube in hot bending, control panel for inputting the job data operating, remote control unit for concetration and distribution of input/output, and the monitoring system which can establish unmanned operationby receiving the bending job data via LAN form a design teamwhich produces the job data and schedule based on master production plan and diagnoses bending data change, input, whole system status, and system malfunctions. By employing this system, 30% of production improvement was achieved was achieved comparing to the existing bending system.

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복강경수술기구의 벤딩메커니즘 해석 및 벤딩커플러 최적설계 (Bending Mechanism Analysis and Bending Coupler Optimal Design for Laparoscopic Surgical Instrument)

  • 황달연;문대환;최승욱;원종석
    • 한국정밀공학회지
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    • 제30권4호
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    • pp.434-441
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    • 2013
  • Bending motion has been used in the surgical instruments with bending structures and tendon mechanisms. A simplified bending angle amplification ratio between the proximal and distal bending joint was derived in this article. The bending structure of disk and rib in the proximal joint was analyzed based on finite element method with an emphasis on the circumferential uniformity of bending stiffness. Regarding the distal joint, optimal design and sensitivity analysis was done with four design variables of outer and inner diameter, rib height and rib width while maximizing the deformation under the stress distribution below the yield stress. Outer diameter and rib width are most critical to maximum deformation as the outer diameter and inner diameters are so to maximum equivalent stress.

두 개의 압출빌렛을 사용하는 'Λ' 단면 앵글 구조재의 압출굽힘가공에 관한 연구 (A Study on the Extru-Bending Process of the Angle Product with 'Λ' Section Using Two Extrusion Billets)

  • 이경국;진인태
    • 소성가공
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    • 제14권2호
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    • pp.160-167
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    • 2005
  • In the present study about extru-bending of angle product, the bending of extruded angle products with the $'\Lambda'$ section and 'ㄱ', section can be obtained using two extrusion billets by the hot metal extru-bending machine with the two punches moving in the different velocity. The bending curvature can be controlled by the different velocity of billets through the two-hole container. This paper describes simulations and experiments of extru-bending process that can make bending during extruding by the difference of stem velocities. And they are applied to two kinds of dies, that is, one of them is conical dies with symmetry $'\Lambda'$ section and the other one is conical dies with asymmetry 'ㄱ' section. The results of the forming simulation by $DEFORM^{TM}-3D$ and results of experiments show that the bending phenomenon at the die exit during extrusion can be obtained with two extrusion billet by the two stems moving in the different velocity. And it was known that it is possible to design the structure of conical cavity of extrusion dies and to control the curvature of product through the simulation and experiment of extru-bending process.

The Effect of Exposure in Elevated Temperatures on Bending Properties of Wood

  • Park, Joo-Saeng;Lee, Jun-Jae
    • 목재공학
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    • 제27권4호
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    • pp.20-29
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    • 1999
  • Temperature has important effect on mechanical properties of wood. These effect needs to be understood and taken into account in the structural use of wood. Furthermore, the effect of cooling after exposing to high temperature must be explained. In this study, the effect of temperature, exposure time, specific gravity, and cooling on bending properties were investigated. The boundary temperatures at which bending MOE and MOR reduced rapidly were approximately $200^{\circ}C$ and $150^{\circ}C$, respectively. This boundary temperature was nearly constant with independence of species(specific gravity), exposure time, and cooling. Above the boundary temperature, the effect of exposure time was increased with temperature and the reduction of bending MOE and MOR for Japanese Larch with relatively higher specific gravity was smaller than that of Hem-fir. The recovery of bending MOE and MOR after cooling was also more significant above the boundary temperature than below. The degree of cooling effect was larger for MOR than MOE. Consequently, bending properties of wood in elevated temperatures should be considered in terms of the boundary temperature, $200^{\circ}C$ for bending MOE, $150^{\circ}C$ for MOR, and these boundary temperatures must be considered an important factor. Furthermore, to evaluate the safety of structure, the recovery after cooling should be considered.

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Cracking and bending strength evaluations of steel-concrete double composite girder under negative bending action

  • Xu, Chen;Zhang, Boyu;Liu, Siwei;Su, Qingtian
    • Steel and Composite Structures
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    • 제35권3호
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    • pp.371-384
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    • 2020
  • The steel-concrete double composite girder in the negative flexural region combines an additional concrete slab to the steel bottom flange to prevent the local steel buckling, however, the additional concrete slab may lower down the neutral axis of the composite section, which is a sensitive factor to the tensile stress restraint on the concrete deck. This is actually of great importance to the structural rationality and durability, but has not been investigated in detail yet. In this case, a series of 5.5 m-long composite girder specimens were tested by negative bending, among which the bottom slab configuration and the longitudinal reinforcement ratio in the concrete deck were the parameters. Furthermore, an analytical study concerning about the influence of bottom concrete slab thickness on the cracking and sectional bending-carrying capacity were carried out. The test results showed that the additional concrete at the bottom improved the composite sectional bending stiffness and bending-carrying capacity, whereas its effect on the concrete crack distribution was not obvious. According to the analytical study, the additional concrete slab at the bottom with an equivalent thickness to the concrete deck slab may provide the best contributions to the improvements of crack initiation bending moment and the sectional bending-carrying capacity. This can be applied for the design practice.

굽힘이력을 고려한 딥드로잉공정의 유한요소역해석 (Finite Element Inverse Analysis of the Deep Drawing Process Considering Bending History)

  • 허지향;윤종헌;바오이동;허훈
    • 소성가공
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    • 제16권8호
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    • pp.590-595
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    • 2007
  • This paper introduces a new approach to take account of bending history in finite element inverse analysis during sheet metal forming process. A modified membrane element was adopted for finite element inverse analysis so that bending-unbending energy was additionally imposed in the total plastic energy, predicting bending-unbending regions using the geometry of the final shape and tools. An algorithm was applied to a cylindrical cup deep drawing process. The blank shape and the distribution of the thickness strain were compared with those obtained from the incremental finite element analysis in order to evaluate the effect of the bending history. The algorithm reduced the difference between the results of the inverse analysis from those of the incremental analysis due to bending history. The analysis was also carried out with the variation of the thickness of the initial blank to investigate the effect of bending deformation. The results showed that the difference was remarkably reduced as the thickness of the initial blank increased. This indicates that the finite element inverse analysis cooperated with the suggested scheme is useful to obtain more accurate results, especially when bending effects are significant.

열린 단면 부재의 굽힘 붕괴 실험 및 해석에 관한 연구 (A Study on the Bending Collapse at the Open Cross-Section Members with Experiment and Analysis)

  • 이승철;강신유
    • 한국정밀공학회지
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    • 제21권4호
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    • pp.132-139
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    • 2004
  • The open section members have been used as the members of vehicle such as automotives, airplanes and trains. When vehicles are crashed, these members have absorption of the energy and it is necessary for retainment of the survival space, and as the result, the prediction for the displacement of members in this case of the crash of vehicles is very important. The displacements of members in this case of the crash of automotives show combined aspect of both axial collapse and bending collapse. In the rollover accident when bending collapse happen, the collapse of each members is progressed by the plastic hinge which made from bending moment, and therefore the research for the behavior of members under bending moment after collapse is necessary to determine the internal energy which the members can absorb and the deformed shapes of the members on the step of design. In this paper, the characteristics of bending collapse at the members of the open cross-section were studied with experiment and numerical analysis. We made a comparative studied of the result of the experiment, and changed the axis according to the parallel-axis theorem.

호흡에 따른 한국무용 굴신동작이 운동학적 변인과 지면반력에 미치는 영향 (Effect of Breathing on Ground Reaction Force and Kinematic Variables dur ing Bending in Korean Dance)

  • 박양선
    • 한국운동역학회지
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    • 제21권3호
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    • pp.327-334
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    • 2011
  • The objective of this study was to develop a scientific approach for investigating Korean dance in detail, and to examine the intense expressions and various movements, which are based on Danjeon breathing. For the purpose, we analyzed the movement changes and distribution of forces resulting from the switch in movement between exhalation and inhalation while bending, which is the most basic movement in Korean dance. The following conclusions were drawn from this study. In Korean dance, bending with breathing involves less back-and-forth-movement and more up-and-down movement, as compared to bending without breathing; this indicates greater body stability and a wider range of movements while bending with breathing. In addition, less time is required for bending with breathing at the point of switching from exhalation to inhalation, and it involves less movement of the supporting leg; thus, vending with breathing involves faster switching from bending movements to extending movements. While bending, the raised leg goes through a less smooth curve while breathing, which indicates stronger movement of the toes. Bending with breathing requires a greater braking force than bending without breathing, and the vertical force, generated by switching from exhalation to inhalation, is transferred to extending movements using the ground load. The results of this study can be potentially employed to investigate the expressions used in Korean dance on th basis of its principle of forces. Korean dance has evolved into various creative forms, and basic analytical studies of these diverse forms and related breathing methods re required in the future.

이종 접합재의 굽힘 및 인장강도에 미치는 시험편 형상의 효과 (Effect of Specimen Geometry on Bending and Tensile Strength of Material Used in Dissimilar Joints)

  • 허장욱
    • 대한기계학회논문집A
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    • 제34권3호
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    • pp.341-346
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    • 2010
  • 이종 접합재($\beta-Si_3N_4/S45C$)의 굽힘강도와 인장강도에 미치는 시험편 형상의 영향을 정량적으로 평가하였다. 평균 굽힘강도와 평균 인장강도는 원형단면 시험편이 4각형 단면 시험편보다 약간 높았다. 또한, 초음파(AE)를 이용하여 균열발생응력을 성공적으로 측정할 수 있었으며, 균열발생응력은 굽힘강도의 60~80% 이었다. 아울러, 세라믹측 접합계면 근처의 잔류응력 측정을 굽힘강도 시험전에 X선 회절법에 의해 실시하였으며, 굽힘강도와 균열발생응력은 잔류응력 증가와 더불어 감소하였다. 마지막으로 인장시험에서 굽힘변형률 성분의 영향을 평가하였으며, 인장강도는 굽힘변형률 성분의 증가와 더불어 감소하고 굽힘강도의 약 80%에 해당되었다.

굽힘반복에 따른 슬랙스 무릎부위의 역학적특성 변화 (Mechanical Properties Change of the Slacks Knee Part by the Bending Time)

  • 이정숙;권헌선;성수광
    • 한국의류산업학회지
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    • 제6권4호
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    • pp.497-502
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    • 2004
  • The mechanical properties of jean slacks to the type of cutting lines in knee region and the bending time, after doing bending 0 times, 500 times, and 1500 times, the effects of whether or not cutting line, the fabric direction of the cutting area, and the number of cutting lines were investigated for tensile, shearing, compression, and mixing value of mechanical properties. The results are as follows: EM to bending times were larger in order of weft