• 한국강구조학회 논문집
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• 제12권2호통권45호
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• pp.143-150
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• 2000

마찰접합용 고장력 볼트 셋트의 관련 규격에서 허용하는 치수공차 범위 내에서 너트 구멍의 편심과 와셔 구멍 지름의 공차는 체결 시 편심에 의한 접촉면적의 결손을 초래하고 체결력의 산포를 유발하는 요인이 된다. 편평한 너트 자리면과 와셔의 접촉시 분포되는 압력의 비선형성을 고려하여 편평한 자리면 형상을 원호곡면으로 바꾸면 초기 선 접촉은 체결이 진행됨에 따라 면 접촉으로 발전한다. 원호 접촉면은 편심에 의한 접촉면적의 결손을 감소시켜 접촉상태가 양호해지므로 자리면 마찰토크(체결력) 안정화에 기여하게 된다. 유한요소법으로 너트와 와셔 접촉면의 압력을 구하고 나사면과 자리면의 마찰계수는 토크계수 A, B급이 포함되도록 조합하고 최대편심 시 토크계수를 계산하였다. 토크계수의 분포로부터 원호자리면의 적정 곡률반지름이 결정된다.

• 한국표면공학회지
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• 제44권1호
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• pp.21-25
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• 2011

This test focuses on the correlation between the lubrication, ductility and strength through the change of nut lubricant which decides joining angle for A490 bolt sets required in the AASHTO (American Association of State Highway & Transportation Officials). Because the lubrication of high tension bolt, nut, washer sets becomes an important factor to ductility and joining load, the quality improvement is required for improving reliability and securing enough lubrication of maker and user. This study examines the quality characteristics required in the specification through tests because only this standard specifies joining quality in the extreme conditions (as much about two times of the joining angle on site as normal condition). Moreover, this study is limited to the test on joining axial force required in the AASHTO for the three nut lubrication conditions of A490 bolt set. It is concluded that the nuts should be coated or waxed enough for the improvement of the joining axial force and ductility of bolts required in the standards. It is shown that in the case of plain high tension bolt sets, a rust preventing lubricative oil shall be applied and the torque coefficient value for A490 bolt sets should be maintained below 0.175.

• 한국안전학회지
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• 제19권1호
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• pp.12-17
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• 2004

By using an experimental approach recently developed to determine the torque-tension relationship for bearing frictional characteristics of several typical bolted joints were studied. The experimental approach allows the direct determination of the bearing friction between the nut and its bearing surface. Detailed friction studies were made on the influences of the size and shape of the hole, the use of a slot in a bolted joint, contact area and position, and other factors such as turning speed, coating, and the use of wax on the bearing surface. The contact area and position of the washer have a marginal effect on the bearing friction. The organic coating on the nuts reduces the bearing friction significantly. Nuts with organic coating over a washer with zinc finish provide the smallest and the most consistent bearing friction. The results from the experimental investigation will be helpful for the better design of bolted joints bearing friction. The results from the experimental investigation Will be helpful for the better design of bolted joints.

• 한국표면공학회지
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• 제48권3호
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• pp.93-99
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• 2015

This test focuses on the correlations between joining axial force at non-room temperature and at room temperature according to the surface treatment (Geomet, Dacro, Green Kote, Armore Galv.). The quality characteristics of the fastening axial force required by the KSB 2819 and EN14399-10 standards were discussed. Surface treatment was implemented to S10T and 10.9HRC sets of bolts under the same environmental factors. Development for the stabilization of the fastening axial force required by each standard should continually be enforced, and the fastening and storage in the field should be maintained at room temperature. Managing stabilization of torque enumerated data is required after application of surface treatment. It is concluded that, by conducting the test of applying surface treatment to effectively manage, each lot-specific rate of axial force at room temperature conditions should be maintained below the maximum 4.47%. The decline rate of axial force should be maintained under 2.15% maximum, and the standard deviation of the room temperature condition should be maintained below 0.5.