• Title/Summary/Keyword: Boring

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A Case on Excavation Plan and Design of Adjacent Railroad Tunnel (근접 철도터널의 굴착계획 및 설계 사례)

  • 김선홍;정동호;석진호;정건웅;서성호
    • Explosives and Blasting
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    • v.20 no.3
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    • pp.59-71
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    • 2002
  • The points of this design case are the planning and excavation method of a new double-tracked railroad tunnel which is approx. 11∼22 meters apart from existing single-tracked railroad tunnel. For the optimum excavation method some needs are required in design stage, such as the reduction of noise and vibration, public resentment, damage of buildings and construction costs. Hence the estimation and application of allowable noise and vibration criterion is important. The ground coefficient (K, n) of this site is determined by field trial blasting. The excavation method is chosen to satisfy the allowable noise and vibration criterion. In addition, in order to ensure the stability of existing single-tracked railroad tunnel, the instrumentation of maintenance level is accompanied during the construction stage. As a result of this design condition, central diaphragm excavation with line drilling and pre-large hole boring blasting is applied to the area within 15 meters apart from existing tunnel. And above 15 meters apart, pre-large hole boring blasting is designed.

A Study on the Characteristics of CNC Deep Hole Machining for Marine Part Materias with the Single Tube System BTA Tools (싱글튜브시스템 BTA공구에 의한 박용부품소재의 CNC 심공가공 특성에 관한 연구)

  • 전태옥;전언찬;장성규;심성보
    • Journal of Ocean Engineering and Technology
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    • v.8 no.1
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    • pp.131-143
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    • 1994
  • The BTA(boring and trepanning association) deep hole machining has an increasing demands because of its wide applications and its good productivity. The main feature of the BTA tools is that the tool cutting edges are unsymmetrically located on the boring head. This provides a stabilizing cutting force resultant necessary for self guidance of the boring head. The BTA tools are capable of machining for having a large length to diameter ratio in single pass. A study of the accuracy and surface finish of holes produced would reveal quite useful information regarding the process. This study deals with the experimental results obtained during BTA machining on SM55C, SM45C steel under differnt machining conditions.

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An Optimization Method for Self-Boring Pressuremeter Holding Test to Determine a Horizontal Coefficient of Consolidation under Partial Drained Soil Conditio (부분배수가 발생하는 지반의 수평압밀계수 결정을 위한 자가굴착식 프레셔메터 유지시험의 최적화 해석법)

  • Kim, Young-Sang
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.370-375
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    • 2005
  • This paper describes a systematic way of identifying the horizontal coefficient of consolidation for clayey soil under undrained condition and silty soil under partial drained condition by applying an optimization technique to the early part of dissipation data measured from the self-boring pressuremeter strain holding test. An analytical solution developed by Randolph & Wroth (1979) was implemented in normalized form to express the build-up and dissipation of excess pore pressures around a pressuremeter as a function of the rigidity index. Horizontal coefficient of consolidation was determined by minimizing the differences between theoretical and measured excess pore pressure curves using optimization technique. It was found that the proposed optimization technique can evaluate in-situ horizontal coefficient of consolidation rationally, which is similar with that obtained from the piezocone dissipation test. Furthermore, proposed method can evaluate appropriate coefficient of consolidation for soil under partially drained condition.

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Effect of Hone Stone on Accuracy of Honing in 2-Cycle Engine Cylinder having Open Hole (열린 홀을 가진 2사이클 엔진실더의 호닝가공시 호닝의 정밀도에 미치는 혼스톤의 영향)

  • 장명진
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.3
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    • pp.143-149
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    • 2000
  • Grinding technology in morden industry society is focusing on research and development for grinding stone and machin-ing parts for the purpose of high accuracy and high efficiency of products. But in order to equip the high technology and high accuracy of micro stone which is one of grinding stone a continuous effort on R& D is require. In this study the honing processing work of 2 cycle engine cylinder for motorcycle which has an open hole is carried out so as to investigate the boring and hone stone effects on accuracy of honing. As the experimental result of this study we could conclude that it is possible to secure good conditions of honing by controlling and keeping appropriate cycle-time in the stage of boring for the prior step of honing.

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Determination of Undrained Shear Strength of Clayey Soils from Self-Boring Pressuremeter Test (자가굴착식 프레셔미터 시험을 이용한 비배수 전당강도 산정)

  • 장인성;권오순;정충기;김명모
    • Journal of the Korean Geotechnical Society
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    • v.16 no.6
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    • pp.117-125
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    • 2000
  • 자가굴착식 프레셔미터 시험(Self-Boring Pressuremeter Test, SBPT)은 지반의 교란을 최소화할 수 있기 때문에 점성토의 비배수 전당강도($S_{u}$ )를 비교적 정확하게 평가할 수 있는 방법 중의 하나로 알려져 있으며, 많은 연구자들에 의하여 SBPT 결과로부터 $S_{u}$ 를 산정하는 여러 가지 방법들이 제안되었다. 본 연구에서는 국내 5개지역에서 총 33회의 SBPT를 수행한후, 기존에 제안된 여러 가지 방법들을 이용하여 $S_{u}$ 를 산정하고, 그 중 변형률 경화 거동을 보이는 지반에서의 $S_{u}$ 를 동일 현장에서 수행한 현장베인시험 결과와 비교. 분석하여 각 방법들의 적용성과 신뢰성을 분석하였다. 그리고, $S_{u}$ 산정 결과에 대한 프레셔미터 멤브레인의 유일한 길이의 영향을 수치해석으로 분석하였으며, 그 결과를 이용하여 기존의 접선영 방법(Subtangent method)을 보정하는 식을 제안하였다. 새로이 보정된 방법으로 산정한 $S_{u}$ 를 현장베인시험 결과와 비교하여 개선 효과를 확인하였다.

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Study on the dynamic stiffness variation of boring bar by Taguchi Method (다구찌 방법을 이용한 보링바의 동강성 변동에 관한 연구)

  • Chun, Se-Ho;Ko, Tae-Jo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.8 no.3
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    • pp.98-104
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    • 2009
  • The objective of this paper is to investigate the effect of factors on the dynamic stiffness variation of boring bar. The experiment was carried out by Taguchi Method and Orthogonal array table. The results indicate that overhang was found out to be dominant factor with 95% confident intervals and feed rate and depth of cut were insignificant. In addition, analysis of loss function shows that loss value increased sharply from 3D to 4D(D is a shank diameter). Consequently, there is critical point which changes property of dynamic stiffness.

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Influence of Chucking Forces upon the Accuracy of Circular Hole in Boring Process on the Turning (선반으로 보링가공 할 때 척킹력이 가공 정도에 미치는 영향)

  • Lee, Sang-Soo;Kang, Shin-Gil;Jeon, Young-Seog
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.2
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    • pp.58-64
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    • 2008
  • The cutting process of materials is accompanied with the elastic and plastic deformation due to chucking forces in the boring process of thin holes on the turning. Upon removal of chucking forces at the end of process, the original shape is remained in the plastic deformation; on the other hand, it is modified in the elastic deformation due to spring back. Fixing materials by chucks on the turning has influence on roundness because the process is conducted with unbalanced distribution load induced from the fixing of three jaws. Moreover, the amount of spring back depends on the magnitude of fixing forces. We studied the change of roundness according to fixing forces as well as the method to reduce the influence of chucking forces.

Influence of fixed pressure on the machining accuracy of inner diameter of hollow shaft (고정압이 중공축 내경의 가공정밀도에 미치는 영향)

  • Jeon, Young-Seog;Jang, Sung-Min;Kang, Shin-Gil
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.19 no.3
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    • pp.381-387
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    • 2010
  • This paper presents a study of the influence of fixed pressure in turning. The effect of roundness error and diameter deformation were studied with respect to the fixed pressure applied inside the cylindrical work piece made by boring tool in CNC lathe. The boring tool used in this study is a tungsten carbide coated. The material of workpiece is SM45C and the machining method is dry cutting. Cutting conditions as cutting speed, feed rate and depth of cut are constant. Finally, the change of fixed pressure had influence on the roundness error and diameter deformation.

Development of Flow Control Block for Hydraulic System of Tunnel Boring Machine (터널 굴착기 유압시스템용 유량 제어 블록 개발)

  • Lee, Jae-Dong;Lim, Sang-Jin
    • Journal of the Korean Society of Mechanical Technology
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    • v.20 no.6
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    • pp.929-935
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    • 2018
  • This paper develops a flow control block for a hydraulic system of a tunnel boring machine. The flow control block is a necessary component to ensure stability in the operation of the hydraulic system. In order to know the pressure distribution of the flow control block, the flow analysis was performed using the ANSYS-CFX. It was confirmed that the pressure and flow rate were normally supplied to the hydraulic system even if one of the four ports of the flow control block was not operated. In order to evaluate the structural stability of the flow control block, structural analysis was performed using the ANSYS WORKBENCH. As a result, the safety factor of the flow control block is 1.54 and the structural stability is secured.

Dynamic behavior of boring bar with continuous system analysis (연속계 해석에 의한 보오링 바의 동적 거동에 관한 연구)

  • Kim, Jeong-Suk;Kang, Myeong-Chang;Park, Soo-Kil
    • Journal of the Korean Society for Precision Engineering
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    • v.11 no.4
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    • pp.38-46
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    • 1994
  • The vibration amplitude of boring bar is generally large at the tool tip, because it has the high length-diameter(L/D) ratio. A new dynamic cutting force model is presented by considering the change of shear angle under dynamic cutting. The boring bar is modelled as a cantilever with dynamic force acting at the tool end point. Based on this realistic continuous system model, the equation of motion of borring bar is solved by numerical computations. A good agreement is found between the proposed model and the experimental results.

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