Prediction of Joining Torque for Bit Depth of Subminiature Bolt

초소형 볼트의 비트 깊이에 따른 체결 토크 예측

  • Lee, Hyun-Kyu (Dept. Mech. and Automotive Eng. Seoul Nat. Univ. of Sci. and Tech.) ;
  • Park, Keun (Dept. Mech. System and Design Eng. Seoul Nat. Univ. of Sci. and Tech.) ;
  • Ra, Seung-Woo (Technology Research Center, Seoul Metal) ;
  • Kim, Jong-Bong (Dept. Mech. and Automotive Eng. Seoul Nat. Univ. of Sci. and Tech.)
  • 이현규 (서울과학기술대학교 기계자동차공학과) ;
  • 박근 (서울과학기술대학교 기계시스템디자인공학과) ;
  • 나승우 (서울금속 기술연구소) ;
  • 김종봉 (서울과학기술대학교 기계자동차공학과)
  • Received : 2014.04.17
  • Accepted : 2014.05.27
  • Published : 2014.08.01


Subminiature joining bolts are required for the electronic parts of gadgets such as mobile phones and watch phones. During the miniaturization of bolt heads, it is difficult to obtain sufficient joining force owing to the risk of shear fracture of the bolt head or severe plastic deformation on the bit region. In this study, the maximum joining torque for the bit depth was predicted using finite element analysis. A shear fracture test was conducted on a wire used in bolt forming. The results of this test were subjected to finite element analysis and a fracture criterion was obtained by comparing the experimental and analysis results. The shear fracture of the bolt head during joining was predicted based on the obtained criterion. Furthermore, the maximum joining torque was predicted for various bit depths. Fracture on the boundary between the bolt head and thread was found to occur in lower joining torque as bit depth increases.


Joining Torque;Subminiature Bolt;Bit Depth


Supported by : 산업통상자원부


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