• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.39-46
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• 2006

In this work a dynamic cutting force model in ball end milling of inclined surface is introduced. To represent the complex cutting geometry in ball end milling of inclined surface, workpiece is modeled with Z-map method and cutting edges are divided into finite cutting edge elements. As tool rotates and vibrates, a finite cutting edge element makes two triangular sub-patches. Using the number of nodes in workpiece which are in the interior of sub-patches, instant average uncut chip thickness is derived. Instant dynamic cutting forces are computed with the chip thickness and cutting coefficients. The deformation of cutting tool induced by cutting farces is also computed. With iterative computation of these procedures, a dynamic cutting force model is generated. The model is verified with several experiments.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.15-16
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• 2010

The field experiments and analyses were performed to apply Post-Tensioned Prestressed Concrete Pavement(PTCP) at the Weigh-in-Motion(WIM) sensor installed sections. The experimental results showed that PTCP could be acceptable for WIM sections because the displacements were negligibly smaller at the cutting location for sensor installation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.102-106
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• 1996

In the ball end-milling process of a 3-dimensional mold, it is important to select cutting conditions and tool path considering the geometrical shape of a workpiece to reduce machining time. In this study, experiments were performed to decide allowable feed rate not breaking stability of system for different geometrical shapes. It was found that downcut is more stable than upcutting in machining side wall and downward is preferable to upward in inclined part depending on the angle of the inclination and depth of cut.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.04b
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• pp.8-8
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• 2002

서멧이란(Cermet) '세라믹 경질상과 금속 결합상의 복합체"를 의미하나 절삭 골구계에서는 좁은 의미의 "TiC 혹은 Ti(CN)을 바탕을 Ni,Co를 결합상으로 하는 초경재료"를 의미한다. 이런한 서멧은 전략 물질적 성격이 강한 Co,W로 구성된 WC-Co 초경 합금을 대체하기 위해 고안되었는ㄴ데 ㄴ놓은 경도와 고온에서의 화학적 안정성, 낮은 비중과 저렴한 원료 가격등이 장점이나 WC-Co에 비해 상대적으로 낮은 인성이 문제점으로 지적 되어왔다.TiC-Ni 서멧의 낮은 인성을 향상시키기 위해 Ti(CN) 고용체를 바탕으로 하고 제2ㅇ, 제3의 탄화물이나 질화물을 첨가하는 개발 연구가 과거 30여 년간 진행되어왔다. 그러나 많은 연구결과가 조성 개발 위주로 진행되어 왔고, 또 실험간의 불일치와 재현성 결여로 인해 보여진 여러 현상에 대한 보편적인 결론을 내리기 힘든 점이 있었다. 특히, 미세구조와 기ㅔ적 특성에 관한 통합적이고 조직적인 연구가 진행되지 못하였다. 이번 발표에서는 발표자 실험실에서 지난 8 년 간 행하여 온 실험 결과를 바탕으로 탄화물서멧에 나타나는 독특한 현상, 고용체 탄질화물의 열역학적 안정성, 서멧 재료의 유심구조, 표면 에너지 및 strain, 에너지가 미세 구조 형성에 미치는 영향, 그리고 표면층 형성 등 서멧 개발에 관한 중요 관심사에 대해 간단히 살펴보려고 한다.해 간단히 살펴보려고 한다.

• Korean Journal of Materials Research
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• v.1 no.1
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• pp.9-17
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• 1991

TiC coating formed on $Si_3N_4-TiC$ composite ceramic by chemical vapor deposition (CVD) has an improved microstructures, better thermal shock resistance and interfacial bonding than TiN coating does. TiN coating formed by CVD, however, has lower friction coefficients against steels and better chemical stability. The experimental results indicate that the coated insert is superior to the uncoated one in flank and crater wear resistance. And the multilayer coating shows an improved wear resistance than the monolayer coating.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.395-404
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• 2021

Purpose. The purpose of present study was to evaluate the effect of changing structural stability of wax disc on the fit of prosthesis when the milling proceeded in order. Materials and methods. Prepared maxillary left first molar was used to fabricate a Ni-Cr alloy reference model. This was scanned to design crown and then wax pattern was milled, invested and cast to fabricate prosthesis. The wax patterns located in a row centrally within a single wax disc were set into a total of five groups ranging from WM1 group that was first milled to WM5 group that was last milled and the number of each group was set as 10. Silicone replica technique was used to measure the marginal gap, axial internal gap, line angle internal gap, occlusal internal gap. Data was evaluated with one-way ANOVA with significance level set at α = .05 and then Tukey HSD test was conducted for post analysis. Results. Marginal gap measured in each group, it was 40.41 ± 2.15 ㎛ in WM1 group, 40.44 ± 2.23 ㎛ in WM2 group, 39.96 ± 2.25 ㎛ in WM3 group, 39.96 ± 2.48 ㎛ in WM4 group, and 40.57 ± 2.53 ㎛ in WM5 group. No significant difference was found between groups. The significant difference between the groups was also not found in the axial internal gap, line angle internal gap, and occlusal internal gap. Conclusion. Internal and marginal fit of single crown to the sequential order of milling processing in the single machinable wax disc did not seem to be affected by the sequence.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.15-29
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• 1996

공작기계의 성능향상의 기본과제인 고정도화, 고능률화, 그리고 자동화를 더욱 강력히 추진하기 위해서는 FMS의 핵심이 되는 Machining Center(MC)에서, 공작물의 자동교환장치, 공구관리장치, 자동계측장치, 절삭상태 감시장치를 보유하고, System의 자동화를 신뢰성있게 하기 위한 자동진단 장치를 포함하는 종합적인 System이 절실히 요구되고 있다. 이와같은 System으로서의 높은 정도 안정성과 신뢰성을 전제로 한다.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.8
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• pp.693-698
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• 2015

Recently, the quality of products after the corresponding machining processes were scrutinized in the interest of maintaining a high product-quality standard. The structure and stability of machine tools are important for the prediction of product quality. A structural analysis needs to be carried out to achieve the stable design of machine tools before the initial design stage in the manufacturing process of a precision product. In this study, a structural analysis was carried out using a finite element analysis (FEA) simulation to obtain the design stability of the main parts of a grinding machine. The sizes and locations of both the maximum stress and deformation in consideration of the cutting force of the chuck, tail stock, and bearing of the grinding machine were analyzed. Finally the grinding machine was successfully developed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.993-998
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• 2002

Ultra precision processing technology is the field which is seriously protected its technology by advanced nations. Because of this reason, this technology is very difficult to supply for domestic companies, also domestic companies are revealed the limit of technology development by itself. And then, those are depend on the technology development of advanced nation, domestic companies are not conquer application step with already developed parts. Of course, some cases of its research are succeed. those are included element technology, system technology and so on, for development of ultra precision processing system. To conquer technology holding ultra precision processing accuracy of no level, active research are needed. In this paper, stability of ultra precision cutting unit is analyzed, this unit is the kernel unit in ultra precision processing machine. According to alteration of shape and material about hinge, stability investigation is performed Through this stability investigation, trial and error is reduced in design and manufacture, at the same time, we are accumulated foundation data for un it control.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.36-36
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• 2018

4차 산업 혁명의 영향으로 인공지능, 로봇이 활발히 이용됨에 따라, 산업은 software 면에서 지능화 및 무인자동화로 빠른 변화를 일으키고 있다. 이에 따라 사용되는 hardware는 고신뢰성 및 고성능화를 필요로 하게 되고, 이들의 내구성 및 장수명화를 요구하고 있다. 하지만 장시간 사용 안정성, 사용 기계 부품의 내구성 향상은 사용부품의 소재, 사용 조건등의 변화를 요구하게 되고, 이들은 학문적 의미에서의 트라이볼로지적 특성 향상이 필연적으로 뒷받침되어야 한다. 본 발표에서는 트라이볼로지적 특성 향상을 위한 표면코팅처리 기술로, 자장여과아크방식을 활용하여 solid carbon을 이용한 무수소 DLC 증착 기술에 대하여 발표하고, 그 응용으로 자동차 부품 및 절삭공구 등에 적용한 사례를 소개하고자 한다.