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

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.132-140
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• 2000

Plasma arc cutting is one of the most widely used processes in metal cutting fields and is a process that produces parted metal plates by cutting them with an arc plasma established between the electrode tip and the plate(workpiece). When the tip-to-workpiece distance varies during cutting, the cut quality, for example the kerf width, is deteriorated by the change of plasma arc. The variations of tip-to-workpiece distance are due to the different factors such as inaccuracies in setting the torch or workpiece, thermal distortions during cutting, and uneven surface of workpiece. The control to keep the tip-to-workpiece distance constant is thus indispensable to improve the flexibility of automatic plasma arc cutting system applications. In this study, an arc sensor which utilizes the electrical signal obtained from the plasma arc itself was developed. The arc sensor has an advantage that no particular sensing device is necessary and real-time sensing of the tip-to-workpiece distance is possible directly under the plasma arc. The relationship between plasma arc voltage and tip-to-workpiece distance was determined through the repeated experimental results. The model was used for developing an automatic tip-to-workpiece distance control system of plasma arc cutting. It could be shown that the proposed system has a successful capability of tip-to-workpiece distance control.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.149-154
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• 2003

The cutting tests of high tensile steel plate(AH36) were carried out using CNC plasma arc cutting machine. Both top and bottom width of kerf and the surface roughness(Ra, Rmax) of cut surface are measured under various cutting conditions such as cutting speed, steel plate thickness, etc. In the CNC plasma arc cutting, the surface roughness decreases as cutting speed increases. The hardness is high up to 4mm depth from the cutting surface. In the cutting speed 1300~2100mm/min, the ratio of proper kerf width(Wt/Wb) is around 2.6. Through the series the series of experiments, the satisfactory cutting conditions of high tensile steel plate were found.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5919-5924
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• 2014

Accumulated dross adhered to the cutting support degrades the cutting accuracy and aggravates the working environment by reducing the efficiency of the dust collector. Furthermore, the cutting machine and product can be damaged by the scattering of molten metal. In this study, an attempt was made to increase the productivity of steel cutting process and improve the working environment by dross control. The dross adhesion characteristics were invested by a cutting experiment and the design concept for a dross removal machine was devised. Finally, a cutting support cleaning system and its operating algorithm were developed. The applicability of the developed system was examined and verified by a long-term field test after installation of the plasma arc cutting system of a shipyard.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.885-886
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• 2012

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.93.2-93.2
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• 2015

플라즈마를 포함한 반응성 가스 공정 분석용 사중극자 질량분석기의 필라멘트의 파손양상을 조사하였다. 또한 유전체 증착층이 이온원 성능에 미치는 영향을 분석하기 위하여 이온원의 일반적인 가동 전압 조건에서 Poisson방정식을 이용하여 전위를 수치 해석으로 구하였다. 사용중 파손된 필라멘트의 파단면을 주사전자현미경으로 관찰결과, 수직으로 절단되는 양상과 직경이 점차 작아지면서 erosion되는 두가지 양상을 보였다. 또한 파단면은 표면균열과 패시팅(faceting) 현상을 보였다. 필라멘트 사용시 가장 큰 문제는 패시팅(faceting)이다. 대부분의 결정에서는 다른 결정면보다 에너지 준위가 낮은 결정면이 존재한다. W 원자는 고온에서 확산 또는 증발하여 표면에서 다시 응축할 때 표면 에너지를 최소화하기 위한 독특한 평형 형상이 만들어 지는데 이것이 패시팅의 구동력이다. 이때 국부적으로 단면적이 감소하는 곳이 생기는데, 이 지점이 집중적으로 가열되고 증발이 가속화하여 파손된다. 파단면을 EDS 분석결과, 산화물을 포함한 F, Fe 및 C이 검출되었다. 이 F과 C는 공정중 사용된 CF4의 분해에 의한 것으로 생각되며, 파손된 필라멘트를 Ar 유도결합 플라즈마로 처리한 결과 이 F, Fe 및 C의 양이 감소하였다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.3
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• pp.112-123
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• 2015

There are many systems for cutting plates or pipes into a desired shape. A typical system is a plasma cutter. It uses plasma, which means that an effective design of the table supporting the workpiece is an important issue in order to ensure a long operational career. Conventional roller-support worktables have a short lifespan due to scratches from the plasma, and it is also difficult to maintain the roller balance. By using a bolt-fastening method, deformation and failure of the final product can occur due to the stress concentration at bolting points. To escape these issues, a polygon support and bracket fastening method was designed. Due to polygons having a number of support surfaces, when one surface has been damaged, it is possible to reuse the support by utilizing a different surface. The bracket-fastening method can extend the worktable lifetime and increase productivity by reducing stress concentration. In this paper, the polygon support/bracket-fastening method is compared with existing technologies. Consequently, performance benchmarks are verified through a structure analysis and experimentation.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1361-1366
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• 2009

This study is to see the internal flow for the plasma cutting fume collector. Plasma cutters are widely used in the canning industry and Fume cause the device because it will affect the performance of the design of dust collector. Therefore, to determine the distribution of the internal flow using CFD and Solver was used for calculated with commercial CFD code STAR-CCM+. The results show that design of chamber was incorrect after passed the filter for exhaust to the fan. And the location of the duct to the influx of dust collector and the design was incorrect. In addition, an array of filter was also inappropriate. As a result, present fume collector need to improvement.

• Journal of Welding and Joining
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• v.35 no.2
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• pp.30-34
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• 2017

The trend of the plasma cutting and laser cutting technology of metal alloys including high strength steel, aluminum alloys for the welding structures has been studied. The high-precision plasma systems offer a denser, higher energy arc that in effect produces a sharper cutting tool and high quality cutting products. The high-quality fiber laser systems with compact design and easy set-up make it ideal for cutting in the pipeline or steel structre manufacturing. This paper covers the scientometric analysis of the high efficient cutting technology which are based on the published research works in the 'plasma and laser', and 'cutting technology' obtained from Web of Science, and deals with the details of the background data of the plasma cutting and laser cutting technology.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1999.06a
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• pp.201-206
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• 1999

The influence of surface preparation methods after plasma cutting on the quality of welding zone is investigated. For comparison. three types of welded specimens are prepared by machining(YM), plasma cutting with light regrinding(WPG) and without regrinding(WP), by using three kinds of materials, carbon steel(S45C), stainless steel(Type304) and aluminum alloy (6061-T6). Nondestructive examination, hardness test, microstructure examination, and fracture toughness test are performed. The results show that there is no appreciable reduction in hardness or fracture toughness in WP specimens. But a little difference in heat affected gone size is observed.