• 한국정밀공학회지
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• 제12권6호
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• pp.112-119
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• 1995

Early fracture and cutting force of ceramic tool for hardened STC3 steel was investigated in this study. It was found that early fracture of ceramic tool was mostly occurred before normal wear was progressed beyond a critical cutting speed and normal wear was performed under the critical cutting speed. The relationships among critical cutting speed, which was a cause of early fracture, suggested cutting cross section, that is, maximum thickness of cut and width of cut, and cutting force were examined. The following conclusions were obtained: (1)Critical cutting speed showed a high value in the case of small maximum thickness of cut and large nose radius, but was not influenced by width of cut, (2)Principal, feed and radial force, respectively, showed the proportional value to constant cutting area, width of cut and maximum thickness of cut orderly, (3)Occurrence of early fracture was dependent upon radial force.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.344-349
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• 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.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.873-874
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• 2006

PCBN tools are used worldwide for machining of hardened steel parts in automotive industries. But in heavy interrupted cutting of hardened steel, the tool life is not so stable by sudden breakage of the cutting edge, and total cost of cutting by PCBN is not so economical compared to the grinding. To solve this problem, new PCBN has been developed. New PCBN has very fine and homogeneous microstructure to increase the toughness of sintered body that it provides a reliable tool life for heavy interrupted cutting.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4637-4641
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• 2023

For nuclear decommissioning applications, a study was conducted to investigate the feasibility of using a laser for long-distance cutting in complex structures. Cutting tests were performed on stainless steel plates with thicknesses ranging from 10 mm to 30 mm at distances of 300 mm-700 mm from the laser head, using a laser power of 6 kW. Remarkably, the 10 mm and 20 mm thick stainless-steel plates were successfully cut at a distance of 700 mm from the head. Based on the trends observed in the results, it is anticipated that these thicknesses could also be cut at distances of approximately 1 m. Similarly, the 30 mm thick stainless-steel plate was effectively cut at a distance of 500 mm from the head. To evaluate the amount of secondary waste generated, the kerf width was measured. Due to the long-distance cutting, the average kerf width ranged from 6 mm to 16 mm. Despite the wider kerf width, long-distance cutting holds promise for efficiently handling hard-to-reach targets in nuclear decommissioning scenarios.

• Journal of Welding and Joining
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• 제14권5호
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• pp.59-68
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• 1996

This study was aimed to characterize the laser cutting process for the cold rolled stainless steel sheet. The principal process parameters of the cutting process were applied to both the continuous wave form and the pulsed wave form for the laser output mode. The laser-oxygen cutting process and the laser-nitrogen cutting process were also considered to characterize the quality and efficiency of the cutting process. The laser-oxygen cutting process revealed the better productivity than the laser-nitrogen cutting process, since the laser energy and the exothermic oxidation energy exerted on the laser-oxygen cutting process simultaneously during the entire cutting process. However, the straightness of the cutting section, which was considered as the most important factors, was inferior to that of the laser-nitrogen cutting process due to the formation of chromum oxide on the cutting surface. Frequency and duration of the pulsed wave form act as the main factors for the better quality, When the frequency increased from 100 Hz to 200 Hz and the duty increased from 20% to 40%, the quality factors such as the height of dross and the surface roughness were improved remarkably. The increase in the frequency from 200 Hz to 300 Hz, on the other hand, revealed the less effective in the cutting quality.

• 한국레이저가공학회지
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• 제4권3호
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• pp.30-39
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• 2001

This work was tamed out to apply a laser welding technique in joining between a Zn coated low carbon steel plate(SECC) and a free cutting carbon steel shaft(SUM24L) with or without W coating. Experiments were carried out and analysed by applying the FD(factorial design)method to obtain the optimum Laser welding condition. Optical microscopy, SEM, TEM and XRD analyses were performed in order to observe the microstructures in the fusion zone and the HAZ. Mechanical properties of the welded specimens were examined by microhardness test, tensile test and twist test. There was no flawed Zn in the fusion zone by EDS analysis. This means that during the welding process, Zn gas could be eliminated by appropriate shielding gas flow rate and butt welding gap. Ni coating itself did not influence on the tensile strength and hardness. However, twist bending strength and the weld depth of the Ni-coated free cutting carbon steel were lower as compared with those of the uncoated free cutting carbon steel. It was attributed to a lower absorbance of laser beam to the shin Ni surface. According to the results of the factorial design tests, the twist bending strength of welded specimens was primarily affected by pulse width, laser power, frequency and speed.

• Geomechanics and Engineering
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• 제23권6호
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• pp.523-533
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• 2020

The current study focuses on the effect of the end shape of steel pipe piles on installation effort and bearing resistance using the pressing method of installation under dense ground conditions. The effect of pile rotation on the installation effort and bearing resistance is also investigated. The model steel piles with a flat end, cone end and cutting-edge end were used in this study. The test results indicated that cone end pile with the pressing method of installation required the least installation effort (load) and showed higher ultimate resistance than flat and cutting-edge end piles. However, pressing and rotation during cutting-edge end pile installation considerably reduces the installation effort (load and torque) if pile penetration in one rotation equal to the cutting-edge depth. Inclusion of rotation during pile installation reduces the ultimate bearing resistance. However, if penetration of the cutting-edge end pile equal to the cutting-edge depth in one rotation, the reduction in ultimate resistance can be minimized. In comparing the cone and cutting-edge end piles installed with pressing and rotation, the least installation effort is observed in the cutting-edge end pile installed with penetration rate equal to the cutting-edge depth per rotation.

• 화약ㆍ발파
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• 제36권2호
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• pp.10-18
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• 2018

철골 구조물의 발파해체에 사용하는 성형폭약은 국내외 대부분의 경우에 사용이 제한적이거나 수급이 불가능하여 적용하지 못하는 경우가 많이 발생한다. 이러한 문제를 해결하기 위해서는 산업용 폭약을 사용하여 금속 제트가 발생할 수 있는 장치가 필요하다. 본 연구에서는 금속 제트가 발생하는 강재 절단용 장약용기를 제작하였다. 절단 성능 실험을 통해 두께 25mm의 강판에 대한 장약용기의 절단 성능을 평가하였다. 또한 침투 과정 수치 모사와 절단 성능 실험에서의 결과를 비교하고, 두께 35mm와 70mm의 강판에 대한 절단 성능을 평가하였다.

• 대한기계학회논문집A
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• 제28권2호
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• pp.196-205
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• 2004

The cutting characteristics and the deformed layer of nitrogen(N)-added type 316LN stainless steel were comparatively investigated to type 316L stainless steel. The cutting force, the surface roughness(Ra) and the tool wear in face milling works were measured with cutting conditions, and the deformed layers were obtained from micro-hardness testing method. The cutting resistance of type 316LN was similar to type 316L in spite of its high strength. The surface roughness of type 316LN was superior to type 316L for all the cutting conditions. In particular, in the high cutting speed above 345m/min, the surface roughness of the two stainless steels was closely same. The deformed layer thickness of the two stainless steels was generated in the 150$\mu\textrm{m}$-300$\mu\textrm{m}$ ranges, and its value of type 316LN was lower than that of type 316L. This is due to the high strength properties by nitrogen effect. It was found that type 316LN was higher in the tool wear than that type 316L, and flank wear was dominant to crater wear. In face milling works of type 316LN steel, tool wear is regarded as a important problem.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 춘계학술발표대회 개요집
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• pp.36-38
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• 2002

This paper is a study on the effect of the cutting speed, length of tip-specimen and cutting thickness in CNC gas cutting of the high-tensile steel plate(AH36). Experiments were performed to investigate the variations of cutting surface, surface roughness and kerf width under various cutting conditions.