• Title/Summary/Keyword: 체결력

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Study of Production and Material Properties of Micro Screw Using SWCH18A and SUS XM7 Materials (SWCH18A 와 SUS XM7 을 적용한 초소형 나사제작 및 물성분석에 관한 연구)

  • Ra, Seung-Woo;Kim, In-Rak;Hwang, Sung Tack
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.9
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    • pp.1043-1048
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    • 2014
  • As micro screws feature reduced screw lengths and pitches, the resulting clamping force diminishes because of the reduced length of the actual joints. The elements of the clamping force are material, geometry, and friction. We studied the shrinking size of the screw and the methods to improve the clamping force by changing the material. We developed a micro screw using SWCH18A and SUS XM7 materials, and obtained the precision and thickness of the pitch through three-dimensional measurement. We also measured the external resistance of the micro screw by applying the Vicker's hardness test and conducted a break surface analysis using a break torque test and SEM for obtaining the break characteristics.

An Experimental Study on the Static Load Capacity of T-Type Tension Joints with High Tension Bolt (고장력볼트 T-인장이음의 정적내력에 관한 실험적 연구)

  • Lee, Seung Yong;Choi, Jun Hyeok;Kim, Kyong Tae
    • Journal of Korean Society of Steel Construction
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    • v.27 no.1
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    • pp.53-61
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    • 2015
  • The tension type joint is a mechanically very efficient connection method, as it directly uses the load capacity of base metal or high tension bolt, the reduction of the number of drilling hole and fastening and the fatigue resistance. It is applied to the joint of girder and cross beam, horizontal joints of towers, beam to column joints, the secondary member joints of deck floor ends, and brackets. In this paper, static load tests for the T-type tension joint were conducted to investigate the structural behavior of the joint. The parameters were bolt diameter, flange thickness, and the reduction of clamping force of the joint. The failure modes and load capacity of joints and the effects of flange thickness, bolt diameter and clamping force were investigated.

Time Dependent Reduction of Clamping Forces of High Strength Bolt F13T (시간에 따른 F13T 고장력 볼트의 체결력 감소)

  • Jo, Jae Byung;Seong, Taek-Ryong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.4A
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    • pp.291-297
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    • 2009
  • Relaxation of high strength bolts was investigated. Block type and splice type specimens were fabricated with different types of bolts and different clamping lengths. Bolts were tightened to the specified torque. Clamping forces were measured through strain gauges installed on the shafts of bolts, while specimens were kept in a constant temperature and humidity. In all cases, ratio of clamping force reduction is less than 10%. Test results of different types of specimens and bolts and different clamping lengths were compared each other by using a simple model, which is suggested in this study for the estimation of bolt relaxation. The suggested model shows reasonably good agreements with test results for all cases. No difference is found between F13T and F10T bolts, but Dacro coated bolts shows higher relaxation than black bolts by approx. 30%. And also the comparison of test results shows that ratios of bolt relaxation become larger as clamping lengths of bolt shorter and the number of faying surfaces greater.

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Slip Behavior of Friction Type High-Tension Bolted Joints with Oversize Hole (과대공을 갖는 고장력 볼트 마찰이음부의 미끄러짐 거동)

  • Cho, Sun Kyu
    • Journal of Korean Society of Steel Construction
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    • v.9 no.3
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    • pp.301-307
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    • 1997
  • In field fabrication of steel members, the oversize hole is frequently required due to reaming and mismatching. But, there are no provisions and investigations about oversize hole in the Korean specifications. So, in this study, the tension test of friction type high-tention bolted joints is performed with parameters of bolt hole size, surface treatment and tightening force, and investigate the effect of slip behavior with those parameters. From the results, the enough tightening force is needed to obtain some degree slip load in shot blast treatment case, although tightening force is reduced somewhat, it is no problem to guarantee slip load in zincrich primer case. The slip behavior of joints with oversize hole(26mm) is similar to the slip behavior of joints with hole of nominal size.

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Launch and On-orbit Environment Verification Test of Flight Model of Hinge Driving Type Holding and Release Mechanism based on the Burn Wire Release (열선분리방식을 이용한 힌지구동형 구속분리장치 비행모델의 발사 및 궤도환경 검증시험)

  • Lee, Myeong-Jae;Lee, Yong-Keun;Kang, Suk-Joo;Oh, Hyun-Ung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.3
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    • pp.274-280
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    • 2016
  • Hinge driving type holding and release mechanism based on the burn wire release for application of cubesat is main payload of STEP Cube Lab. (Cube Laboratory for Space Technology Experimental Project) to be launched at 2015. It has high constraint force, low shock level as well as surmounting drawbacks of conventional nichrome burn wire release method that has relatively low constraint force and system complexity for application of multi-deployable systems. In this paper, we have proposed a flight model of holding and release mechanism for the verification of the constraint force and deployment status signal acquisition. To validate the effectiveness of the flight model, launch and on-orbit environment verification test have been performed.

Estimation of Long Term Clamping Force of High Strength Bolts By Coating Thickness Parameters of Slip Faying Surfaces (미끄럼 표면 도막두께변수에 따른 고력볼트 장기축력 예측)

  • Nah, Hwan-Seon;Lee, Hyeon-Ju;Ryoo, Jae-Yong;Choi, Sung-Mo
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.3 no.1
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    • pp.8-15
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    • 2012
  • The initial clamping forces of high strength bolts depending on different faying surface conditions drop within 1,000 hours regardless of loading, any other external force or loosening of the nut. This study is focused on an expectation model for relaxation of high strength bolt, which is confined to creep on coated faying surfaces after initial clamping. The range of this experiment is limited to estimate the relaxation of bolted joints coated by inorganic zinc primer. The candidate bolts were dacro-coated tension control bolts. The parameters of coated thickness for the faying surface were 96, 168,and $226{\mu}m$ respectively. From experiments, it exhibited that the logarithmic function for creep strain was derived due to the parameter of coating thickness. By using the creep strain, subsequently the quantitative model for estimating long term relaxation of high strength bolt can be taken with the elapsed time. The experimental results showed that the relaxation after the initial clamping of high strength bolt rose to a much higher range from 10% to 18% due to creep of the coating as the coating thickness was increased. This study showed that the clamping force reflecting relaxation after the elapse of constant time can be calculated from the initial clamping force of high strength bolt.