SWCH18A 와 SUS XM7 을 적용한 초소형 나사제작 및 물성분석에 관한 연구

나승우(Seung-Woo Ra),김인락(In-Rak Kim),황성택(Sung Tack Hwang) 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.9

체결부품의 사이즈가 작아질수록 실제 접합부의 면적이 줄어들기 때문에 체결력은 감소한다. 이러한 체결부품의 체결력을 결정하는 요소는 소재(Material), 구조(Geometry), 마찰(Friction)이 있다. 본 연구에서는 체결부품의 사이즈가 줄어들면서 체결력을 향상시킬 수 있는 방법 중의 하나인 소재 변경에 대하여 연구하였다. SWCH18A 와 SUS XM7 을 적용하여 초소형 나사를 제작하였으며, 3 차원 치수 측정을 통하여 피치정밀도와 두께정밀도를 측정하였다. 비커스 경도 측정을 통하여 나사가 외부의 힘에 의해 변형에 대한 저항력을 분석하였다. 또한 파단토크 시험과 SEM 을 이용한 파단면 분석을 통해 파단특성을 분석한다. 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.

A Study on the Clamping Improvement of Precision Screws according to the Materials and Thread Changes

황우채(Woo Chae Hwang),나승우(Seung Woo Ra) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.6

In this study, we compare the performance of the screw through the Clamping force of the test materials to change shape and structure, one of the ways to maintain and improve the engaging force to cope with the miniaturization of the fastener threads are further thinner and lighter precision way that can improve the fastening force of the screw results were as follows. The clamping force according to the materials was 7.57Nㆍcm in SUS XM7 and SWCH18A was 5.97 Nㆍcm. This result was to be found to average 13.5% high in the Clamping force of SUS XM7 materials. In the case of the clamping force of the screw thread shape change, the clamping force of symmetrical and asymmetrical thread was 6.78 Nㆍcm and 7.57 Nㆍcm. The clamping force of the asymmetrical thread showed an average high of 11.6%.

단면형상이 다른 Al/CFRP 혼성박육부재의 축압궤특성

황우채(Woo Chae Hwang),이길성(Kil Sung Lee),차천석(Cheon Seok Cha),김지훈(Ji Hoon Kim),나승우(Seung Woo Ra),양인영(In Young Yang) 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.9

본 연구에서는 Al/CFRP 혼성 구조부재가 승용차용 사이드부재에 사용될 것을 상정하여 Al/CFRP 혼성 구조부재의 단면형상의 변화, 최외각층의 변화가 압궤 특성에 어떠한 영향을 미치는가를 실험적으로 고찰하여 수송기계의 경량화를 위한 사이드부재로 사용될 수 있는 설계 데이터를 얻고자 하였다. 실험결과 다음과 같은 결론을 얻었다. 최외층각이 0°로 적층된 원형 Al/CFRP 혼성 충격 흡수부재가 사각 Al/CFRP 혼성 충격 흡수부재 보다 52,9%, 모자형 Al/CFRP 혼성 충격 흡수부재 보다 49.93% 높게 나타났으며, 최외층각이 90°로 적층된 경우 원형 Al/CFRP 혼성 충격 흡수부재 사각 Al/CFRP 혼성 충격 흡수부재 보다 50.49% , 모자형 Al/CFRP 혼성 충격 흡수부재 보다 49.2% 높게 나타났다. In the present study, we aimed to obtain design data that can be used for the side members of lightweight cars by experimentally examining the types of effects that the changes in the section shape and outermost layer of an aluminum (Al)/carbon fiber reinforced plastic (CFRP) composite structural member have on its collapse characteristics. We have drawn the following conclusions based on the test results: The circular Al/CFRP composite impact-absorbing member in which the outermost layer angle was laminated at 0° was observed to be 52.9 and 49.93 higher than that of the square and hat-shaped members, respectively. In addition, the energy absorption characteristic of the circular Al/CFRP composite impact-absorbing member in which the outermost layer angle was laminated at 90° was observed to be 50.49 and 49.2 higher than that of the square and hat-shaped members, respectively.

단면형상이 다른 Al/CFRP 혼성박육부재의 축압궤특성

황우채(Woo Chae Hwang),이길성(Kil Sung Lee),양용준(Yong Jun Yang),김지훈(Ji Hoon Kim),나승우(Seung Woo Ra),양인영(In Young Yang) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.4-3

On Clamping Force Characteristics in M1.4 Subminiature Screw for CFRP Stacking Angles

김정호(Jung Ho Kim),나승우(Seung Woo Ra),김희성(Hee Seong Kim),김지훈(Ji Hoon Kim) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.6

Recent development of core techniques the IT electronics industry can condense into lightweight and slimmer. In this circumstance, researches for the lightweight materials and subminiature screw have been attracted. In this study, the CFRP was produced by stacking angle to obtain the tensile properties. And Comparing the coated screws and non-coated screws on the specimen, and evaluating the adequacy for the application of CFRP using the result. So The clamping force measured by comparison evaluation. Low screw reverse and Superior torque value at each stacking angle were found the optimum conditions, when Subminiature Screw is applied on smart devices. Both tensile strength and stiffness of [±0°]<SUB>10</SUB> is the highest. Followed by [90°/0°]<SUB>10</SUB> is the highest. The largest clamping torque is [90°/0°]<SUB>10</SUB> When Subminiature Screw is applied coating and non-coating to prevent loosening. Based on the above, Subminiature Screw should be applied in smart devices, because [90°/0°]<SUB>10 </SUB>meet both tensile properties and clamping force.

컴퓨터용 Lead Screw의 자동검사 시스템 개발

배진호(Bae, Jin-Ho),나승우(Ra, Seung-Woo),유필상(Yu, Pill-Sang),김성관(Kim, Sung-Gaun) 한국산학기술학회 2010 한국산학기술학회논문지 Vol.11 No.11

컴퓨터용 Lead Screw는 검사방식이 수동검사로 이루어져 작업자의 주관적 판단으로 인한 미검출과 과검출이 발생하고, 생산성이 저하되는 단점이 있다. 따라서 본 연구에서는 이러한 단점을 보완하고자 Lead Screw 자동검사 시 스템을 개발했다. 검사시스템은 Lead Screw 자동공급 및 이송을 위한 공급․이송 장치와, 표면검사를 위한 360° 회전 장치, 치수검사를 위한 머신비젼 부분으로 구성된다. Lead Screw 자동검사 시스템으로 표면과 치수 측정결과, 오검률 및 미검률이 수동검사 결과보다 우수함을 보였다. In manual inspection of Lead Screw of computers many workers are needed to inspect samples, and its main disadvantage is that such types of inspection system not only gives low production, but also gives low perfection. Besides, in manual inspection system, the inspection cost of samples is higher than that of the automatic inspection system. Therefore, in this study to compensate these shortcomings, an automatic inspection system is developed. For the inspection of the surfaces and different dimensional parameters of computer Lead screw, a 360° rotating machine vision system is developed. From the detailed analysis of the inspection results using the present developed inspection system, it is observed that the developed Lead Screw automatic inspection system is superior to those of manually inspection system.

Torx 형상 나사머리 검사 알고리듬

하종은(Jong Eun Ha),나승우(Seung Woo Ra) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.4-3

비트 깊이에 따른 볼트 체결응력 해석

이현규(Hyun Kyu Lee),나승우(Seung-Woo Ra),김종봉(Jong-Bong Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

As the thickness of IT produce such as mobile phone and watch phone reduce, the size of bolts also should be reduced. These days, bolts of sub-millimeter diameter are used. Even though the bolt size is reduced, the bolt should have enough joining force. The joining force of bolt is dependent on thread shape, screw head thickness, and bit shape. In this study, the effect of bit depth on the joining force is investigated.

광선추적기법을 사용한 정밀나사 비전검사 광학계의 최적설계

백순보(Soon Bo Baek),박근(Keun Park),나승우(Seung Woo Ra) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.6

유한요소해석을 사용한 초소형 나사의 체결력 평가

민경빈(Kyeong-Bin Min),박근(Keun Park),나승우(Seung-Woo Ra) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

Recent trends in the miniaturization and weight reduction of portable electronic parts have driven the use of subminiature screws with a micrometer-scale pitch. As both screw length and pitch decrease in subminiature screws, the resulting clamping force becomes diminishes. To improve clamping force of subminiature screws, a new screw design is considered by modifying screw thread angle: the thread angle is varied as an asymmetric way unlike the conventional symmetric thread angle. Finite element (FE) analyses were performed in order to compare the clamping characteristics of each subminiature screw with different thread angle. The effect of thread angles on the clamping force is then discussed in terms of structural safety for both screws and workpieces.