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Selection of machining conditions for microchannels in ultraprecision diamond turning
Duong, Thanh-Hung,Kim, Hyun-Chul,Lee, Dong-Yoon SAGE Publications 2013 PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGIN Vol.227 No.10
<P>In ultraprecision machining for microchannels, deformation occurs with high frequency because the diamond tool pushes against the channel structure during the machining process. Conservative cutting conditions decrease the cutting force and avoid deformation, but they reduce productivity. Therefore, it is important to select suitable cutting conditions in practice. This article presents a theoretical decision model for optimum machining conditions in manufacturing rectangular micropatterns. The model involves the prediction of cutting force and deformation. To forecast deformation phenomena, a rectangular pattern was considered as a cantilever beam with a distributed load, and the maximum principal stress that acts on the rectangular micropatterns could then be determined. For verifying this solution, several experiments were carried out to obtain a rectangular pattern by single-point diamond turning. Finally, the machining condition decision model was implemented and verified in practice.</P>
김우순,채왕석,김동현,난바의치 한국공작기계학회 2003 한국공작기계학회 춘계학술대회논문집 Vol.2003 No.-
To obtain the surface roughness with range from 10nm to lnm, we need a ultra-precision machine, cutting condition, and the study of materials. And we have to also consider the chip and vibration of diamond tool during processing. In this paper, the cutting conditions for getting mirror surface of aluminum alloy have been examined experimentally by using ultra-precision turning and single crystal diamond tool. In generally, the cutting conditions have effect on the surface roughness in ultra-precision turning. The result of surface roughness was measured by the ZYGO New View 200.
이준용(Joon-Yong Lee),배찬열(Chan-Yeol Bae),김창호(Chang-Ho Kim) 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.3
This study presents the optimal hardness range for a coated layer of a workpiece when the diamond tool cuts the corner-cube pattern on the coated plates using an ultra-precision diamond-turning machine. Two kinds of coated plates, which have the hardness range of 211~328 Vickers hardness, are used on the first experiments. The form accuracy for the corner-cube pattern could be achieved through the following experiments using the accumulated thin copper plates in second experiments, having optimal 265~275 Vickers hardness based on the basic first experiments without tool wear. When the number of machining adjustments was increased to seven times, having machining depth was reduced successively in second experiment, a fine surface could be achieved without tool wear.
Design and Manufacture of an Off-axis Aluminum Mirror for Visible-light Imaging
Jizhen Zhang,Xin Zhang,Shuanglong Tan,Xiaolin Xie 한국광학회 2017 Current Optics and Photonics Vol.1 No.4
Compared to one made of glass, an aluminum mirror features light weight, compact design, low cost,and quick manufacturing. Reflective mirrors and supporting structures can be made from the same material,to improve the athermal performance of the system. With the rapid development of ultraprecise machiningtechnologies, the field of applications for aluminum mirrors has been developed rapidly. However, mostof them are rotationally symmetric in shape, and are used for infrared applications. In this paper, the designand manufacture of an off-axis aluminum mirror used for a three-mirror-anastigmat (TMA) optical systemat visible wavelengths is presented. An optimized, lightweight design provides a weight reduction of morethan 40%, while the surface deformation caused by earth’s gravity can meet the required tolerance. Thetwo pieces of an off-axis mirror can be diamond-turned simultaneously in one setup. The centrifugaldeformation of the off-axis mirror during single-point diamond turning (SPDT) is simulated through thefinite-element method (FEM). The techniques used to overcome centrifugal deformation are thoroughlydescribed in this paper, and the surface error is reduced to about 1% of the original value. Afterpost-polishing, the form error is 1/30 λ RMS and the surface roughness is better than 5 nm Ra, whichcan meet the requirements for visible-light imaging.
절삭 깊이의 무작위 제어를 적용한 다이아몬드 선삭공정에서 소재회전 반경에 따른 미세패턴의 크기변화 분석 연구
정지영,한준세,최두선,제태진,Jeong, Ji-Young,Han, Jun-Se,Choi, Doo-Sun,Je, Tae-Jin 한국금형공학회 2020 한국금형공학회지 Vol.14 No.1
Ultra-high brightness and thin displays need to optical micro-patterns which can uniformly diffuse the lights and low loss. The micro random patterns have characteristics to rise the optical efficiency such as light extraction, uniform diffusion. For this reason, various fabrication processes are studied for random patterns. In this study, the micro random patterns were machined by diamond turning which used a controlled cutting tool path with random cutting depth. The machined patterns had random shape and directionality along the circumferential direction. The average width and length of machined random pattern according to rotation radius were 40.13㎛~55.51㎛ and 37.25㎛~59.49㎛, and these results were compared with the designed result. Also, the machining error according to rotation radius in diamond turning using randomly controlled cutting depth was discussed.
Experiment-based statistical prediction on diamond tool wear in micro grooving Ni?P alloys
Kim, S.J.,Le, D.,Lee, S.W.,Song, K.H.,Lee, D.Y. Elsevier 2014 Diamond and related materials Vol.41 No.-
Diamond tool wear in grooving micro patterns on nickel alloys has caused an increase in the pattern geometry defect rate over time. Therefore, it is important to be able to understand and predict diamond tool wear and tool life. However, as experiments related to diamond micro grooving are extremely expensive and time consuming, the problem of limited data must be faced. In this paper a new method of predicting diamond tool wear which combines experimental equations with statistics is introduced. The wear model shows the relation of cutting condition, safe wear and probability, which was built by the first experiment. The predicted average wear was the same as the measured value of the verification experiment and the probability was a little smaller than the verification experiment due to the bigger standard deviation of the first experiment, which was not stable compared to the verification experiment.
단결정 다이아몬드 공구에 의한 Corner Cube 가공 시, 형상정밀도에 미치는 동 도금층의 경도의 영향
이준용(J. Y. Lee),김창호(C. H. Kim),서충완(C. W. Sea) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.5
This article presents machining experiments to assess the relationship between the profile accuracy and the workpiece hardness using a natural diamond tool on an ultra-precision diamond turning machine. The study is intended to secure a corner cube prism pattern for reflective film capable of high-quality outcomes. The optical performance levels and edge images of corner cubes having various hardness levels of the copper-coated layer on a carbon steel plate are analyzed. The hardness of the workpiece has a considerable effect on the profile accuracy. The higher the hardness of the workpiece, the better the profile accuracy and the worse the edge wear of the diamond tool.
초고온·고압 소결 공정으로 제조된 다결정 다이아몬드 컴팩트(PDC)의 VTL 마모 특성에 미치는 Co 제거의 영향
백민석,김지원,박배건,박희섭,이기안 대한금속·재료학회 2020 대한금속·재료학회지 Vol.58 No.7
Polycrystalline diamond compact (PDC) has excellent wear resistance, high impact resistance, superior fatigue properties, and has been used in the oil and gas drilling industries. This study investigated the effect of Co leaching on the microstructure, vertical turning lathe (VTL) wear properties of PDCs manufactured by high-temperature and high-pressure (HTHP) sintering. The VTL wear test has the advantage of simulating the actual oil drilling environment by using granite as the workpiece. PDC sintered material that did not receive Co leaching was named HTHP sintered PDC-A, and the material subjected to Co leaching was called Co-leached PDC-B in this study. As a result of XRD analysis of both PDCs, diamond and WC peaks were detected, and only the HTHP sintered PDC-A exhibited some Co peaks. In the HTHP sintered PDC-A, the binder WC and Co were evenly distributed at the diamond interface. However, in the Co-leached PDC-B, some empty spaces were observed at the diamond interface. The HTHP sintered PDCA exhibited a similar or slightly higher VTL wear resistance than the Co-leached PDC-B, but only in the short sliding distance. In the long sliding distance after 9 km, Co-leached PDC-B showed significantly superior wear resistance compared to the HTHP sintered PDC-A. The HTHP sintered PDC-A exhibited both abrasive and adhesive wear behaviors, while the Co-leached PDC-B showed only abrasive wear. Based on the above results, the VTL wear mechanism of PDCs, and ways of improving wear resistance were also discussed.
정지영,최환진,박종성,심종근,김영재,곽은지,최두선,제태진,한준세 한국정밀공학회 2024 한국정밀공학회지 Vol.41 No.2
Here in, a high-quality automotive camera lens was developed based on an ultra-precision diamond turning core and cyclic olefin polymer (COP) injection molding process. To improve surface roughness and achieve the accuracy of plastic injection molding lens, systematic mold core machining process was developed and demonstrated using the diamond turning machine. The cutting tool path was generated by using NanoCAM 2D, and it was partly revised to prevent interference between the cutting tool and the workpiece. After the initial machining using the generated tool path, the compensationcutting process was conducted based on the measured surface profile of an initially machined surface. After two times of compensation machining, the fabricated core mold showed a shape error of 100 nm between peak to valley (PV) and Arithmetic mean roughness (Ra) of 3.9 nm. The performance of the fabricated core was evaluated using an injection molding test. Injection molded aspheric plastic lens showed contrasts that were higher than 55% at 0.0 F, 30% at 0.3 F, and 20% at 0.7 F without any moiré phenomenon that meets the specification for automotive vision module with 1MP and 140o field of view.
Improvement in Surface Roughness by Multi Point B Axis Control Method in Diamond Turning Machine
김영복(Young-Bok Kim),황연(Yeon-Hwang),안중환(Jung-Hwan An),김정호(Jeong-Ho Kim),김혜정(Hye-Jeong Kim),김동식(Dong-Sik Kim) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.11
This paper details a new ultra-precise turning method for increasing surface quality, “Multi Point B Axis Control Method.” Machined surface error is minimized by the compensation machining process, but the process leaves residual chip marks and surface roughness. This phenomenon is unavoidable in the diamond turning process using existing machining methods. However, Multi Point B axis control uses a small angle (<1 °) for the unused diamond edge for generation of ultra-fine surfaces; no machining chipping occurs. It is achieved by compensated surface profiling via alignment of the tool radial center on the center of the B axis rotation table. Experimental results show that a diamond turned surface using the Multi Point B axis control method achieved P-V 0.1 μm and Ra 1.1nm and these ultra-fine surface qualities are reproducible.