• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.210-215
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• 2008

This paper presents an experimental study on a bending actuator with a shape memory alloy wire. In this study, we introduced design process and experimental result of the bending actuator. The bending actuator consists of a SMA wire, springs, and a glass/epoxy strip. In the bending actuator, springs were used to restore the SMA wire to its initial shape right after actuation. To obtain properties of the SMA wire, DSC test was performed and the behavior of the SMA wire under different loadings was observed. Finally, the proposed bending actuator shows reasonable actuation behavior with relatively lower power consumption, fast response and effective efficiency.

• 대한기계학회논문집A
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• 제25권1호
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• pp.161-167
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• 2001

The overhead transmission wires operating both at warm temperature and tighten state for a long period of time in a power transmission plant are degraded by air pollution, wind, creep and slip between steel wire and aluminium conductor. The objective of this study is to investigate to investigate the characteristics of fatigue properties with tension and bending loading of a high carbon steel wire. The fatigue behaviors have been carried out by tension-tension, 4 points bending and 3 points bending loading. In the present study, a conventional fatigue strengths between 4 points bending and tension-tension fatigue were determined by Gerber, Sorderberg and Goodmans theory and we investigated S-N diagram for bending and tensile loading.

• 한국기계가공학회지
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• 제7권4호
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• pp.50-55
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• 2008

CNC wire bending machines are used in industries to make a type variety of wire products such as long links. The machines have a long arm device to rotate in order to remove forming errors by flexibility of wire. Generally, the machines which constructed servo motors in the arm have the rotating range of the arm under 360 degree because the servo motors connect with fixed control devices on frame by many cables. The rotating angle under 360 degree limits working speed and forming geometry. Therefore this study developed a gear train to drive a parts in arm and to be independent on arm rotation movement. The developed gear train can transfer four movements to four components in arm and is consists parallel of four pairs of satellite gear trains. This study constructed the CNC wire bending machine with the developed gear train and verified that the gear train could drive internal components independently on arm rotation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.274-279
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• 2000

The overhead transmission wires operating both at warm temperature and tighten state for a long period of time in a power transmission plant are degraded by air pollution, wind, creep and slip between steel wire and aluminium conductor. The objective of this study is to investigate a high carbon steel wire. We tested for basic mechanical properties and 3 types fatigue behavior, tension-tension, 4 points bending and 3 points bending fatigues. In this study, a conventional fatigue strengths between 4 points bending and tension-tension fatigue were determined by Gerber, Sorderberg and Goodman's theory and we investigated S-N diagram for bending and tensile loading.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.464-467
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• 2003

In this paper, we analyzed on the characteristics of the stranded wire disconnected by bending stress. The stranded wire that used in the experiment are PVC insulated flexible cords(VCTFK) of $0.75mm^2,\;1.25mm^2,\;and\;2.0mm^2$. They are used to connect the load in low voltage. The stranded wires disconnected by bending stress were magnified with optical microscope. Using X-ray, the disconnected wire were photographed. we compared mechanical characteristics of the stranded wire between disconnected tendency and allowable current. On the mechanical strength of vinyl captyre ellipse type cords under bending stress, $1.25mm^2$ VCTFK was the strongest of them. When it was bended $826.3{\pm}7\;times$, it appeared the disconnected tendency that element wires of $1.25mm^2$ VCTFK are more about 1.67 times than element wires of $0.75mm^2$ VCTFK. In mechanical strength, $1.25mm^2$ VCTFK is higher about 1.7 times than $0.75mm^2$ VCTFK. Therefore, we found out that mechanical strength will be higher, if element wire is a lot. In comparison with bending stress, $1.25mm^2$ VCTFK is the strongest among samples, and then it is the most useful in wires of movable type.

• Journal of the Korean Wood Science and Technology
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• 제13권4호
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• pp.67-72
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• 1985

To improve the bending strength of sawdustboard, verious resin contents of 10, 13, 16, and 19% were applied to the thin shell (face layer) composed with wire net or not. The shell effect of sawdust and wire net composition formed with core sawdustboard were evaluated. Forcusing on the effects of wire net composition and noncomposition including a comparison with chipboard and veneer complyboard, bending properties (Modulus of rupture (MOR), Modulus of elasticity (MOE), Stress at proportional limit ($S_{pl}$). Work to maximum load ($W_{ml}$))were analyzed and discussed. 1. In modulus of rutpute, veneer comply was the highest (621.5 kg/$cm^2$), and next decreasing order was wire net composition (159.1 kg/$cm^2$), chipboard (81.75 kg/$cm^2$), and wire net noncomposition (76.21 kg/$cm^2$) as in modulus of elasticity, work to maximum load, except for stress at proportional limit. 2. The highly significant effects were shown in both wire net composition and noncomposition, at the same time wire net composition exceeded two times of noncomposition throughout resin contents in bending properties. Chipboard was similar to the mean or 16% resin content in noncomposirion. 3. Every board in wire net composition above 10% resin content was beyond 100 kg/$cm^2$ in MOR, minimum allowable strength for structural use according to KS F 3104. In conclusion, the feasibility for improving the bending strength of weak sawdustboard by wire net composed shell was offered.

• 한국초전도ㆍ저온공학회논문지
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• 제25권4호
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• pp.19-23
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• 2023

The Second-generation high-temperature superconducting (HTS) Rare-Earth Barium Copper Oxide (REBCO) wire is a composite laminate having a multi-layer structure (8 or more layers). HTS wires will undergo multiple loads including the bending-tension loads during winding, high current density, and high magnetic fields. In particular, the wires are subjected to bending stress and magnetic field stress because HTS wires are wound around a circular bobbin when making a high-field magnetic. Each of the different laminated wires inevitably exhibits damage and fracture behavior of wire due to stress deformation, mismatches in thermal, physical, electrical, and magnetic properties. Therefore, when manufacturing high-field magnets and other applications, it is necessary to calculate the stress-strain experienced by high-temperature superconducting wire to present stable operating conditions in the product's use environment. In this study, the finite element model (FEM) was used to simulate the strain-stress characteristics of the HTS wire under high current density and magnetic field, and bending loads. In addition, the result of obtaining the neutral axis of the wire and the simulation result was compared with the theoretical calculation value and reviewed. As a result of the simulation using COMSOL Multiphysics, when a current of 100 A was applied to the wire, the current value showed the difference of 10^-9. The stress received by the wire was 501.9 MPa, which showed a theoretically calculated value of 500 MPa and difference of 0.38% between simulation and theoretical method. In addition, the displacement resulted is 30.0012 ㎛, which is very similar to the theoretically calculated value of 30 ㎛. Later, the amount of bending stress by the circular mandrel was received for each layer and the difference with the theoretically obtained the neutral axis result was compared and reviewed. This result will be used as basic data for manufacturing high-field magnets because it can be expanded and analyzed even in the case of wire with magnetic flux pinning.

• 소성∙가공
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• 제17권8호
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• pp.649-656
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• 2008

Springback is one of factors affecting precision in metal forming. Its effect is particularly prominent in bending process. In this study, bending and forging process are used in order to manufacture a micro spring with two bending region from $60{\mu}m$ diameter wire. Springback in the process lowers the precision of the micro spring. Overbending for springback compensation has wide usage in a general way. However, this method requires repeated modifications of press dies until the tolerance is allowable, which causes that production cost and time increase. In this paper, we analyzed the mechanism of springback in the forming process of the micro spring using finite element method. In addition, a simple method to control springback without modifying dies was proposed by performing numerical analysis with various parameters.

• 대한치과교정학회지
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• 제22권3호
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• pp.647-656
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• 1992

The purpose of this study was to evaluate the elastic memory process in cold worked stainless steel wire and the effect of heat treatment on it. 0.018 inch round and $0.019\times0.025$ inch rectangular wire (ORMCO stainless wire) were used in this study. Each wire type had 4 groups: non-heat treatment group, furnace heat treatment group, electric current heat treatment group, and bending after heat treatment group. Each group was consisted of 10 specimens. With the Jig, each wire was bent into v-shape uniformly, and width of two free ends of each v-shaped wire was measured by caliper (to the point of 0.1 mm correctly) at time interval of offjig, after heat treatment, 1, 2, 3, 4 hours, 1, 2, 3, 4, 5, 6 days, 1, 2, 3, 4 weeks after. The results were as follows: 1. In non-heat treatment group and bending after heat treatment group, elastic memory process was occured $60\%$ within 1 hour, and more than $90\%$ within 1 week. 2. In furnace and electric current heat treatment group, almost all elastic memory process was occured during teat treatment, and then specimen was stabilized dimensionally. 3. Magnitude of deformation by elastic memory was greater in heat treatment group than non heat treatment group and bending after heat treatment group. 4. There was no remarkable difference in deformation pattern between 0.018 inch round wire and $0.019\times0.025$ inch rectangular wire.

• Composites Research
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• 제22권2호
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• pp.37-42
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• 2009

이 논문은 형상기억합금 선재를 이용한 굽힘 작동기의 실험적인 설계방법을 다루고 있다. 제안된 굽힘 작동기는 유리섬유 프리프레그를 이용하여 만든 스트립, 스프링 그리고 형상기억합금 선재로 구성된다. 굽힘 작동기에서 스트립은 초기에 형상기억합금 선재에 초기하중을 가하기 위하여 굽힘 형태로 정되며, 스프링은 형상기억합금 선재가 작동 후 빠른 시간내에 초기 형상으로 돌아오기 위한 보조수단으로 사용된다. 먼저 형상기억합금 선재의 특성을 알아보기 위하여 시차주사열량계(DSC)를 이용한 실험, 여러 종류의 초기 하중을 가한 후 작동 성능 실험, 인장 시험, 온도 변화에 따른 기계적 거동을 조사하였다 이를 바탕으로 스트립, 스프링, 인가 전압에 의한 영향을 관찰하고 소모전력을 분석하여 굽힘 작동기를 설계하였다. 특정 조건을 갖는 굽힘 작동기는 낮은 소모전력으로 빠른 응답성능을 나다내었다.