• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.6
• /
• pp.837-844
• /
• 2001

Jet cutting technology currently makes use of a generic supersonic gas jet to improve the cutting speed and performance. In order to get a better understanding of the flow characteristics involved in the supersonic jet cutting technology, the axisymmetric Navier-Stokes equations have been solved using a fully implicit finite volume method. Computations have been conducted to investigate some major characteristics of supersonic coaxial turbulent jets. An assistant gas jet has been imposed on the primary gas jet to simulate realistic jet cutting circumstance. The pressure and the temperature ratios of the primary and assistant gas jets are altered to investigate the major characteristics of the coaxial jets. The total pressure and Mach number distributions, shock wave systems, and the jet core length which characterize the coaxial jet flows are strongly affected by the pressure ratio, but not significantly dependent on the total temperature ratio. The assistant gas jet greatly affects the basic flow characteristics of the shock system and the core length of under and over-expanded jets.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.344-349
• /
• 2003

The purpose of this study is to ascertain the ability of New type cutter using Hybrid Rocket Propulsion System to cut normal carbon steel and also compound metal like stainless steel which cannot be cut by regular oxygen-acetylene cutter. To compare cutting performance, Two different types of experiment with oxygen-acetylene and Hybrid Combustion cutters were performed. As a result, Hybrid Combustion cutter is used to cut both carbon steel and stainless steel with cutting speed of 400mm/min(carbon steel) and 250mm/min(stainless steel). Otherwise, oxygen-acetylene cutter can be used to cut only carbon steel with cutting speed of 500 $^{\sim}$ 700mm/min. The possibility of Hybrid Combustion cutter as a cutting machine was confirmed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.4 no.1
• /
• pp.37-42
• /
• 2005

The localization of manufacturing technique development is actualizing for low cost with supplies of display devices. We need more high cutting technique because consumers want flat glasses of various sizes. Recently, most general two methods are normal wheel cutting and laser cutting, but both of them have some faults. First, the wheel cutting has cracks and sharp edges of sections. Second, it is easy for laser cutting to cut curved lines. however, it has thermal damage and low traverse speed. I suggest a new cutting method by high-wave frequency vibration wheel cutting(HFVC), which is good for quality improvement. Vertical cracks and crack depth is observed, after HFVC. When the average of the crack depth is $30{\mu}m$ and the average of the wallner liner depth is $200{\mu}m$, it has the most high quality of the sections in this experiment. As a result, when we consider between the normal wheel cutting method and the HFVC method, the latter has low cracks and good quality.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.12 no.2
• /
• pp.20-26
• /
• 2013

This study focused on how it affects the surface roughness of work piece in cutting SCM415 steel, widely used steel in industry, by TiCN and TiN tools. Following conclusion was drawn from several experiments. The surface roughness of heat treated workpiece was better than that of non heat-treated materials. Moreover, the roughness of surface roughness(Ra 0.25) on feeding rate of 0.05 was better when it was in wet process, rather than dry process. As the feeding rate increases, TiCN coating tool shows better roughness of surface than TiN tool. Also, in heated treatment, TiCN coating tool shows the least straightness dimension deviation at feeding rate of 0.05, 0.15mm/rev, and concave-like R shape appears by the feeding rate orders of 0.05, 0.15, 0.1, 0.125 and 0.075mm/rev.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1995.03a
• /
• pp.70-80
• /
• 1995

광학용 정밀유리와 건축용 패널유리 전문가공을 위한 CNC Glass Scribing Machine 을 개발하였다. 이제까지는 고품질의 고가기계를 수입하여 사용하던가 간이 자동화된 자체 개발기계를 사용하여 여유있게 절단한후 연삭가공에서 정밀칫수를 맞추는 작업을 해왔었다. 그러나 금번 개발된 기계를 사용하여 작업한 결과 연삭공정을 생략할수 있음은 물론 가공칫 수 정밀도도 일급 수준을 얻을수 있었다. 그러나 아직 세계일류의 품질과 성능은 도달치 못 했다. 생산성 향상을 위한 이송속도 향상설계와 가공칫수 정밀도의 초일급 달성을 위한 초 정밀설계를 통해 품질과 성능에서 세계일류의 상품화 개발과정을 준비중에 있다. 본논문에 서는 본 기계의 개발과정 및 주요요소기술들과 개발 결과를 정리하였다.

• Korean Journal of Construction Engineering and Management
• /
• v.19 no.6
• /
• pp.115-123
• /
• 2018

The primary objective of this study is to develop an all-in-one based steel pipe pile cutting robot prototype that improves the conventional steel pipe pile head cutting work in safety, quality, and productivity. For this, the following research works are conducted sequentially; 1)literature review and expert survey, 2)selection of core technology using AHP analysis, 3)deduction of detail design, 4)verification of structural stability, 5)development of full-scale prototype. As a result leveling laser and laser detector(94.46), plasma cutter(96.72), rotary grapple(98.45) are selected as a core technologies. As an outcome, it is analyzed that gripper, cylinder pivot bracket and gripper base are structurally stable. Their maximum stresses are shown as 43.0%, 19.4%, 5.3% compared to their yield strength respectively. The development of full-scale prototype in this study will be utilized for the development of the all-in-one attachment based steel pipe pile cutting robot commercialization model.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.3
• /
• pp.1-7
• /
• 2004

Abrasive water-jet(AWJ) machining can cut various materials such as metal, glass and plastics. However, the AWJ machining has some troubles including kerf, rounding and side taper. In this study, we experimently investigated the correlation between the traverse speed of the abrasive water-jet and the dimensional error of the workpiece according to the thickness and the types of the material. The specimen was the stainless steel and the mild steel and the predetermined contour cutting was conducted. A comer radius error, an uncut width and a kerf were measured and evaluated.

• 유공압시스템학회:학술대회논문집
• /
• 2010.06a
• /
• pp.66-69
• /
• 2010

A punched pipe in a muffler for an automobile has many important variables, like location of holes in the pipe and length of the pipe related to noise reduction of a diffuser. This pipe is cut depending on length of product and this process, generally workers cut pipes by hands. In this process, there are many errors and it relies on the skill of workers, so it can happen that cycle time for complete product gets long and productivity gets low. Therefore, we need a vision system to distinguish holes in the punched pipe and a transfer system to set the cutting position automatically by moving the pipe depending on forward and backward part of the holes. This paper explains the development of an automatic transfer device which will cause the beating pipe to be cut correctly, exactly the same length as the product.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1997.11a
• /
• pp.20-20
• /
• 1997

고강도 알루미늄 대형 링롤재를 급냉할 때 발생하는 잔류응력을 2차원 및 3차원 유한 요소 해석하였고, 3단계 절단법에 의해 측정된 변형율과 ABAQUS의 요소제거 기능을 이용한 해석 값을 직접 비교하였다. 급냉후 잔류응력 해석결과는 2단과시효 후 측정값과 비슷한 경향을 보였으나 그 절대값의 차이가 크게 나타났다 이는 시편 링의 높이가 작아 실험 값이 부정확하였기 때문이며 링의 높이를 증가시켜 높이방향으로 균일한 응력분포를 갖도록 하면 그 차이가 감소될 것으로 판단된다. 잔류응력을 측정하는 3단계 절단 과정을 모사한 3차원 해석결과와 측정된 변형율을 직접 비교함으로써 실험과 해석의 정확성을 향상시킬 수 있도록 하였다. 이로부터 잔류응력이 존재하는 일반적인 알루미늄 구조물의 기계가공에 의한 변형을 정확히 예측할 수 있는 기반을 마련하였으며 구조해석 시 잔류응력의 영향을 고려할 수 있게 되었다.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.9
• /
• pp.68-74
• /
• 1999

The influence of surface preparation methods after plasma cutting on the quality of weld zone was investigated. For comparison, three types of welded specimens were prepared by machining (WM), plasma cutting with light regrinding (WPG) and without regrinding (WP), by using three kinds of materials, carbon steel (SM45C), stainless steel (STS304) and aluminum alloy (A6061-T6). Nondestructive examination, hardness test, microstructure examination, and fracture toughness test were performed. The results showed that there was no appreciable reduction in hardness or fracture toughness in WP specimens. But a little difference in heat affected zone size was observed.