• Title/Summary/Keyword: Shape of the Drilled hole

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Drilled Hole Variation of Air Bearing Spindle for PCB according to RUNOUT (PCB드릴링용 공기베어링 스핀들의 런아웃(RunOut)에 따른 가공 홀의 형상변화)

  • Bae M.I.;Kim S.J.;Kim H.C.;Kim K.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1555-1558
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    • 2005
  • In this study, we measured cylindricity and Runout of the air bearing spindle, and tested PCB(printed circuit boards) drilling with 0.4mm micro drill at 90,000rpm and 110,000rpm in order to obtain drilling hole error. Results are as follows; The air bearing spindle's Runout was not so high within $10\mu{m}$ from 20,000rpm to 80,000rpm but it grew after 80,000rpm. Drilling hole size error was 9% at 80,000rpm and 12% at 110,000rpm because of spindle's Run out. Drilled hole shape falsified more 110,000rpm than 90,000rpm.

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A Study on the Effect of the Components of Cutting Resistance upon Friction between Drill and Inside Wall of Drilled Hole in Drilling (Drill가공시 Drill과 가공구명내벽과의 마찰이 절삭저항성분에 미치는 영향)

  • Koo, Youn-Yoog
    • Journal of the Korean Society for Precision Engineering
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    • v.2 no.3
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    • pp.28-40
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    • 1985
  • In this study, to check up on the effect of the components of cutting resistance upon friction between drill and inside wall of hole in drilling, the experiment was performed with individual specimen of carbon steel, cast iron, aluminium alloy under various cutting conditions: depth of hole, cutting speed, feed rate, shape and material of specimen. On the basis of the experimental results, the following conclusions are drawn; 1. The components of cutting resis- tance were increased in proportion to the increase of depth of hole owing to frictional resistance of drill margin and chip-jamming. 2. As feed rates increase, torque and thrust were increased. When comparing to the increasing rate for these components respecitively, thrust is higher tendency than torque. 3. As drill diameter increase, torque and thrust were increased. When comparing to the increasing rate for these components respectively, torque is higher tendency than thrust. 4. In the case of torque, the frictional resistance between drill margin and inside wall of drilled hole accounts for about 20 percent of carbon steel, 14 of cast iron, 10 aluminium alloy in drilling. But the effect of thrust force could be negligible. 5. Comparison between the theoretical and experimental results showed a close agreement so far as depth of hole is about three times of drill diameter. But there was a wide difference between them beyond the rane of three times, because of characteristics of the drilling process.

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AJM을 이용한 HDM에 의한 잔류응력 계측에 관한 연구 1

  • 이택순
    • Journal of Welding and Joining
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    • v.6 no.3
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    • pp.37-42
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    • 1988
  • The Hole Drilling Method(HDM) is widely used to measure residual stresses in the welded structures. The purpose of this study is to evaluate the accuracy fo measuring residual stresses when drilling the hole by Air-abrasive Jet machine(AJM). Simulated residual stresses wre introduced by applying known stresses to steel bars. These known streses were then compared with measured stresses relaxed from hole drilling. the obtained results are summarized as follows; 1) It was possible to obtain well defined holes with the nozzle designed for this study. 2) If the hole shape is not cylindrical, critical may occur. 3) In the uniaxial strain field, the measurement error of the maximum principal stress was within .+-.10 percent. The orientation angle of the maximum principal stress was within 8.deg. from the given directioin. 4) meausrements were made varying hole depths. Little or no change of stresses occurs since holse were drilled more than the depth of the 0.6 times diameter. 5) The air-abrasive jet machining for drilling holse does not cause appreciable apparent stresses which si critical to measure residual stresses.

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An Experimental Study for Machined Patterns of Friction Surface on Disc Brake Rotor in Performance Aspect (디스크 브레이크 로터 마찰면 가공 형태에 따른 성능 변화 연구)

  • Jung, Taeksu;Cha, Bawoo;Hong, Yunhwa;Kim, Cheongmin;Hong, Younghoon;Cho, Chongdu
    • Transactions of the Korean Society of Automotive Engineers
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    • v.24 no.4
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    • pp.471-479
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    • 2016
  • Cross-drilling and slotting on the frictional surface of a brake rotor are methods used for improving the performance of the brake system. These shapes have particular advantages, such as the shaving effect of a slotted shape, which maintains a clean pad-to-rotor contact surface, and the venting effect of a drilled shape, which provides passageways for the gas to escape. In order to understand the effect of the machined pattern on the brake performance aspect, an experimental method is adopted along with the dynamometer test. The cross-drilled rotor, slotted rotor, and mixed pattern rotor with cross-drilling and slotting machining are prepared and tested in terms of friction coefficient, temperature, braking torque, and noise.

Optimal Design of Dielectric shape and Topology using Smooth Boundary Topology Optimization Method (부드러운 경계 위상 최적설계기법을 이용한 유전체 형상 및 위상 최적설계)

  • Jeung, Gi-Woo;Choi, Nak-Sun;Kim, Nam-Kyung;Kim, Dong-Hun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.10
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    • pp.1936-1941
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    • 2009
  • This paper deals with a new methodology for topology optimization in which the topology of the design domain may change during the shape optimization process. To achieve this, the concept of the topological gradient is introduced to compute the sensitivity of an objective function when a small hole is drilled in the domain. Based on shape and topological sensitivity values, the shape and topology of the design domain may be simultaneously changed during design iterations if necessary. To verify the advantages and also to facilitate understanding of the method itself, two electrostatic design problems have been tested by using 2D finite element analysis: the first is the inverse problem of a simple dielectric model and the second is the rotor design of a MEMS actuator.

Structural Behavior of Holed RC Beam mixed with Sawdust (폐톱밥 혼입 RC 유공보의 구조거동에 관한 실험적 연구)

  • Son, Ki-Sang;Lee, Jae-Hyeong
    • Journal of the Korean Society of Safety
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    • v.21 no.1 s.73
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    • pp.96-104
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    • 2006
  • This study is to find out how the sawdust-mixed RC beam with holes acts compared to two case of normal one with sawdust without hole, without sawdust. variables are ED3H1, ED3H2, ED3H1UB, ED3H2L, ED5H1, ED5H1UB, ED5H2, ED5H2L, Normal with sawdust PLA without sawdust. All sand, aggregate, cement are in accordance with KS. mixing design is also in accordance with KS and done at D remicon company in order to decrease any error in mixing manually. ED3H1 showed 7tone of maximum load capacity having only minor tensile deformation around hole, compared to the center of the beam. ED5H2L showed almost same shape of tensile strain between hole area and center of two beam length, while having 9.5 tone load capacity, incase of two holes being in the longitudinal axis. But ED5H2 in case of two holes being in same forcing direction showed 8.4tone of load capacity while having minor tensile chape around hole and normal tensile shape in the center of beam length. Two diameter 3cm hole in longitudinal axis give more effective behavior than the other case, practically. Capacity decrease between 5cm and 3cm in eccentric position form the longitudinal axis is less than percents. There is minor capacity difference between hole diameter 3cm hole, but 13tone difference of load capacity between hole diameter 5cm.

A Study on Characteristics of the Unit Skin Friction Using the Wall Roughness in the Soft Rock (연암부 벽면거칠기를 이용한 단위주면마찰력 특성에 관한 연구)

  • Hong, Seok-Woo;Hwang, Geun-Bae
    • Journal of the Korean Geotechnical Society
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    • v.35 no.12
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    • pp.7-13
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    • 2019
  • In the case of the drilled shaft, one of the methods for calculating unit skin friction stress of rock socket parts is to measure the roughness of the excavated face. This method is to estimate the unit skin frictional resistance using a device which measures the roughness shape of the excavated face in the excavation step. In this study, the roughness shapes of the face of the rock socket part in the drilled shaft were measured directly in the perforated hole and the results are used to identify the characteristics of the unit skin friction of the bedrock. In addition, the static load test and the load transfer test were performed on the same pile to verify the result of the roughness test.

Development of an Automated System for Predicting Shape and Volume of Air Pocket on the Draw Die (드로우 금형의 에어 포켓 형상 및 체적예측 자동화 시스템 개발)

  • Jung, Sung-Yuen;Hwang, Se-Joon;Park, Warn-Gyu;Kim, Chul
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.1
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    • pp.72-78
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    • 2008
  • Metal stamping is widely used in the mass-production process of the automobile. During the stamping process, air may be trapped between the draw die and the panel and/or between the punch and the panel. Air pocket rapidly not only increases forming load in the final stage, but also deforms the product just formed by compressive air inside the air pocket in knockout process. To prevent these problems air bent holes are drilled in the die to exhaust the trapped air but all processes associated with air bent holes are performed by empirical know-how of workers in the field due to lack of researches. Therefore this study developed an automated design system for predicting the shape and position, and volume of air pocket on the draw die by using the AutoLISP language under AutoCAD circumstance. The system is able to display the shape of air pocket occurred in the draw die and to calculate automatically its volume by strokes. So it makes a stepping stone to calculate theoretical size of an air bent hole and numbers according to it by predicting and analyzing the position and volume of air pocket. Results obtained from the system enable the designers or manufacturers of the stamping die to be more efficient in this field.

Development of 3-D Modeling for Abrasive Waterjet Drilling Process (어브레시브 워터젯에 의한 Drilling의 3차원 모델링 연구)

  • Kwak, Hyo-Sung;Kovacevic, Rodovan
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.7
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    • pp.7-14
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    • 1999
  • 어브레시브 워터젯을 이용한 Drilling시 깊이에 대한 예측은 가장 중요한 변주중의 하나다. 이 논문에서는 구멍 깊이의 예측 및 구멍 형상을 연구하기 위하여 3차원 해석 모델이 제안되었다. 해석 모델은 크게 두 가지로 구성되었다. 하나는 비선형 반복 방정식에서 생성된 입자의 운동식이며, 다른 하나는 수많은 입자에 의한 충돌시 가공능력을 규정지우는 Constitutive Equation으로 구성되었다. 이 모델은 구멍 가공이 진행됨에 따라 발생하는 감쇠 효과를 고려하였다.실험적인 고찰이 해석모델의 유용성을 검증하기 위하여 이루어졌으며, 근사한 결과를 보였다.

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