• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.137-142
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• 1995

고정밀도와 높은 생산성을 갖는 가공방법은 좋은 제품을 값싸게 제작하여야 하는 당면과제를 해결하기 위하여 필수적인 조건이 되었다. 이를 위하여 우선적으로는 공작기계가 고강성과 고속용 스핀들을 지녀야하며 정밀한 신속한 위치제어가 가능해야한다. 이와 더불어 절삭가공의 최첨병인 절삭공구가 고속가공에서 고정밀도와 오랜수명을 보장하는 우수한 성능 또한 가장 중요한 요소중의 하나이다. 이를 위하여 고속도강으로부터 시작하여 초경합금, ceramic, CBN & PCD 공구로 이르는 고속용 재종개발이 계속되었고 또한 절삭저항의 감소와 원활한 칩배출을 위한 형상개발이 꾸준히 이루어져왔다. 이와 함께 주어진 공작기계와 공구를 사용하여 최고의 효율과 정밀도를 유지할 수 있는 최적의 절삭조건의 선정과 적용 또한 중요하다.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.16-21
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• 2005

The cutting characteristics of hardened steel(AISI 52100) by PCBN tools is investigated with respect to cutting force, workpiece surface roughness and tool flank wear by the vision system. Hard Owning is carried out with various cutting conditions; spindle rotational speed, depth of cut and feed rate. Backpropagation neural networks(BPNs) are used for detection of tool wear. The input vectors of neural network comprise of spindle rotational speed, feed rates, vision flank wear, and thrust force signals. The output is the tool wear state which is either usable or failure. The detection of the abnormal states using BPNs achieves $96.8\%$ reliability even when the spindle rotational speed and feedrate are changed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.1
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• pp.96-101
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• 2000

Ceramic, PCD and CBN tools are available for the difficult-to-cut-materials such as hardened carbon tool steel, stainless steel, Inconel 718 and etc.. Ceramic toolsare likely to be chipped and abruptly broken before the appearance of normal wear in turning. Ther2efore ceramic tools are suitable for continuous cut in turning not for intermittent in milling. In this study, TiN/TiCN multi-layer coated ceramic tools were found to restrain the chipping, breaking and early fracture and to increase the critical cutting speed owing to TiN/TiCN multi-layer coating in Arc Ion Plating of PVD method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.1
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• pp.10-16
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• 2002

This study is to evaluate the tool performance in honing using diamond reamer and present grounds whether the localized products are sufficiently competitive comparing with the existing imported ones. The heads of the tool performance evaluation are roundness, roughness, tool life of the workpiece and so on. When evaluating the tool performance, cutting process is divided by three areas which are rough semi-finish and finish cut. cloning improves the accuracy such as boring and reaming after manufacturing the inside diameter, and finishing directly by honing is a recent trend. This honing is used greatly In hard cutting materials like cemented carbides and it is the CBN and diamond that is used in hard cutting materials. Both of them are expensive and most oi them are imported.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.452-455
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• 2005

The cutting characteristics of hardened steel by a PCBN tool is investigated with respect to workpiece surface roughness, cutting force and tool flank wear of the vision system. Backpropagation neural networks (BPNs) were used for detection of tool wear. The neural network consisted of three layers: input, hidden and output. The input vectors comprised of spindle rotational speed, feed rates, vision flank wear, and thrust force signals. The output was the tool wear state which was either usable or failure. Hard turning experiments with various spindle rotational speed and feed rates were carried out. The learning process was performed effectively by utilizing backpropagation. The detection of the abnormal states using BPNs achieved 96.4% reliability even when the spindle rotational speed and feedrate were changed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.9
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• pp.1520-1530
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• 1997

Machining pressed compacts of ceramic and WC-Co materials can be the most cost effective way of forming the bodies prior to sintering when the required number of pieces is small. In this study, in order to clarify the machinability for turning, the $Si_3N_4$ and the WC-Co green compacts unsintered were machined under different cutting conditions with various tools. Absorbing chips by vacuum hose decreases tool wear. The tool wear becomes larger in the order of the ceramic, CBN and cemented carbide tools in machining the $Si_3N_4$ green compacts. In machining the WC-Co green compacts, the tool wear becomes larger in the order of the ceramic, cemented carbide and CBN tools. The land of cutting edge does not affect tool wear. When machining with cemented carbide tool, the tool wear i equal cutting length is nearly identical in spite of the increase of cutting spee, and the roughness of machined surface was the best in the cutting speed of 90 m/min. The tool wear decreases with the increase of rake angle and relief angle and with the decrease of nose radius. The machined surfaces become worse with the increase of feed rate and depth of cut, and with the decrease of rake angle and relief angle. The tool wear is not affected by the feed and depth of cut.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.6
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• pp.1002-1012
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• 1997

When the presintered ceramics are machined with ceramic tool, the tool life becomes extremely short. The CBN tool exhibits the best performance in dry machining of the ceramics presintered at $1450^{\circ}C$ among all cutting tests. The roughness of the machined surface of the ceramics presintered below $1350^{\circ}C$ is smaller than that of the ceramics presintered at $1450^{\circ}C$ While the performance of the cemented carbide and CBN tools is better in dry than in wet machining, the diamond tool shows adverse tendency. The tool life is not affected by the feed rate and depth of cut. During the following full-sintering after the machining of the presintered ceramics, the surface roughness decreases up to 62%. The finished surface in machining the presintered ceramics is much better than that in machining the full-sintered ceramic.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.14-20
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• 1998

Automatic finishing process requires the development of high efficient and precision abrasive machining method for dies and molds. This study describes the evaluation of the finishing characteristics, such as surfrace roughness, topography and material removal depth of the electrolytic mixed abrasive machining methods. Experimental setup is composed of 3 axis machining center, a newly developed finishing attachment with constant pressure, electrode and electrolytic bath. Finally, we achieved a successful result that surface roughness is $0.01\mu$m Ra and material removal depth is $120\mu$m using electrolytic(0.8A. 30V) mixed abrasive (#400 CBN, #320 SiC) machining method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.5
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• pp.469-476
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• 2009

Hard facing overlay welding in high chromium carbide is a representative way of extending the fatigue life or recompensing damage, because workpiece surface is uniformly overlay-welded by alloy material. In general, grinding process is currently used for finish due to hardness of weld material. The development of tool material, such as PCBN, has made it possible to use turning instead of grinding. There are many advantages of hard Owning, as lower equipment costs, shorter setup time, fewer process steps, higher material removal rate, better surface integrity and the elimination of cutting fluid. In this paper, machining characteristics and cutting performance are examined to investigate turning possibility of overly welding in high chromium carbide.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.98-104
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• 2020

In this work, a study on the 5-axis machining of ball gear cam is conducted which is a continuation of reference [1]. The ball gear cam used in this study delivers motion in conjunction with the ball supported by the turret. Therefore, it requires carbonizing heat treatment and is usually completed using a 4-axis machining with a carbide ball end mill. If the nose part of the ball end mill is not allowed to participate in the machining, then CBN tools without the nose part can be used. However, machining of certain shapes can be carried out only by contacting the ball in some of the areas on either side which can improve the surface of the machining. This requires a 5-axis machining in order to maintain a constant angle for the processing path. Therefore, in this work, the 5-axis machining method is studied in order to maintain the direction of the cutter axis at a constant angle with the tangent direction of the curve-ball gear cam. Furthermore, the 5-axis machining program for the ball gear cam was developed and the machining experiment was completed and verified.