• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집C
• /
• pp.83-87
• /
• 2001

A 110 mm diameter aspheric metal secondary mirror for a test model of an earth observation satellite camera was fabricated by ultra-precision single point diamond turning (SPDT). Aluminum alloy for mirror substrates is known to be easily machinable, but not polishable due to its ductility. A harder material, Ni, is usually electrolessly coated on an Al substrate to increase the surface hardness for optical polishing. Aspheric metal secondary mirror without a conventional polishing process, the surface roughness of Ra=10nm, and the form error of $Ra={\lambda}/12({\lambda}=632nm)$ has been required. The purpose of this research is to find the optimum machining conditions for reflector cutting of electroless-Ni coated Al alloy and apply the SPDT technique to the manufacturing of ultra precision optical components of metal aspheric reflector.

• 대한기계학회논문집
• /
• 제14권6호
• /
• pp.1515-1522
• /
• 1990

본 연구에서는 천연다이아몬드의 인선형상을 R형과 S형으로 구분하여 제작하 고 미세이송과 절삭속도 변화를 주어 이에 얻어지는 표현거칠기, 칩 생성기구 및 경면 성을 검토하였다.

• Journal of Astronomy and Space Sciences
• /
• 제22권1호
• /
• pp.13-20
• /
• 2005

지상 및 우주 천체 망원경용 비구면 반사경면 초기 제작공정에는 고정입자 휠을 사용하는 연삭이 있다. 본 연구에서는 매 연삭 가공 이전에 설정한 목표 표면조도를 달성할 수 있도록 입력 연삭변수들을 결정하고, 표면 가공오차를 추적하며 , 가공 경과시간을 최소화하는 새로운 연삭공정을 개발하였다. 특별히 이 공정 기법은 이전 연삭 가공 작업시 까지 수집된 입력 변수 및 가공 결과 표면조도 자료를 다 변수 회귀분석 방법에 대입하여 목표 표면조도에 따른 최적 연삭가공 입력변수를 매 가공 작업 시 진화적으로 제시하는 지능형 공정 조절 능력을 갖추고 있다. 개발된 공정기법과 초정밀 컴퓨터 수치제어 연삭기를 사용하여 $96.1\~65.0nm(Ra)$ 범위 의 목표 표면조도를 갖는 제로듀어 소재에 대하여 10회 가공 실험을 수행 한 결과 $=-0.906{\pm}3.38(\sigma)nm(Ra)$의 가공 정밀도를 달성하여, 지능형 연삭공정의 효율을 입증하였다. 이러한 연구결과는 천체망원경용 반사경면 연삭 가공 시 정성적 경험에 의존하여 가공하는 기존 기술을 극복하고 정량적 수치 모형에 의하여 가공소요시간 최소화 및 나노미터 급 표면조도를 달성하는 진화형 공정 최적화 기술의 확립이라는 의의를 가지고 있다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 춘계학술대회 논문집
• /
• pp.97-101
• /
• 1995

This paper describes a new surface finishing process which uses magnetic abrasive polishing. This is applied to automatic finishing of die & mold surface. Nowadays, most of die & mold meanufaturing procedures have been automated by the introduction of NC machine tool and CAD/CAM system. But the surface finishing of die & mold must be done by hand work of well-skilled workers. Though many attempts were tried in the past 15 years to eliminate this hand work, the automatic finishing of die & mold surface with 3D curvature has not been achieved yet. New magnetic abrasive finishing process is thought as one of the possible methods for the automation of 3D surface finishing. In order to improve the grindability of the method, ultra-high speed and 5-axis machining was introduce. The magnetic abrasive polishing which has adopted these methods was confirmend to improve the efficiencyof die & mold surface finishing.

• 한국기계가공학회지
• /
• 제8권3호
• /
• pp.1-6
• /
• 2009

This paper presents a geometrical error compensation of tool alignment for sharp edge bite on B axis controlled machine. In precision micro patterning, bite alignment is crucial parameter for machined surface. To decrease bite alignment error, plus tilted bite from B axis center is touched to reference work piece(pin gauge) and checked the deviation from original position. Same process is repeated for maximum touch deviation value. From this touched position value, wheel alignment error in X axis and Z axis can be calculated on B axis center. Experimental results show that this compensation method is efficient to correct sharp edge bite alignment.

• 한국기계가공학회지
• /
• 제18권7호
• /
• pp.56-62
• /
• 2019

The high-precision laser scriber carries out scribing alumina ceramic substrates for manufacturing ultra-small chip resistors. The ceramic substrates are loaded, aligned, scribed, transferred, and unloaded. The entire process is fully automated, thereby minimizing the scribing cycle time of the ceramic substrates and improving the throughput. The scriber consists of the laser optical system, pick-up module of ceramic substrates, pre-alignment module, TH axis drive work table, automation module for substrate loading / unloading, and high-speed scribing control S/W. The loader / unloader unit, which has the greatest influence on the scribing cycle time of the substrates, carries the substrates to the work table that carries out the cutting line work by driving the X and Y axes as well as by adsorbing the ceramic substrates. The loader / unloader unit consists of the magazine up / down part, X-axis drive part for conveying the substrates to the left and right direction, and the vision part for detecting the edge of the substrate for the primary pre-alignment of the substrates. In this paper, the laser scribing machining simulation is performed by applying the instrument mechanism of each component module. Through this study, the scribing machining process is first verified by analyzing the process operation and work area of each module in advance. In addition, the scribing machining process is optimized by comparing and analyzing the scribing cycle time of one ceramic substrate according to the alignment stage module speed.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1993년도 춘계학술대회 논문집
• /
• pp.108-113
• /
• 1993

The material for the machine tool structure should have high static stiffiness and damping in its property to improve both the static and dynamic performances. The static stiffness of a machine tool can be inceased by using either higher modulus material in the structure of a machine tool. However, the machine tool structrue with high stiffness but low damping is vulnerable to vibration at the resonance frequencies of the structure . For the high precision and highsped machine tool structure, therefore, the high damping capacity is most important in order to suppress vibration. The damping of a machine tool can not be increased by increasing the static stiffness. The best way to increase the damping capacity of the machine tool structure is to use a composite material which is composed of on material with high stiffness with low damping and another material with low stiffness with high damping. Therefore, in this paper, the bed of the ultra high precision grinding machine for mirror surface machining of brittle materials such as ceramics and composite materials was designed and manufactured with the epoxy concrete material. The epoxy concrete material was prepared by mixing epoxy resin with different size sands and gravels. The modulus, compressive strength, coefficient of thermal expansion, specific heat, and damping factor were measured by varying the compaction ratio, sizes and contents of the ingredients to assess the effect of the processing parameters on the mechanical properties of the material. Based of the measured properties, the prototype epoxy resin concrete bed for the mirror surface CNC grinding machine was designed and manufactured.

• 한국정밀공학회지
• /
• 제19권10호
• /
• pp.195-201
• /
• 2002

This paper deals with the precision grinding for aspherical surface of optical parts. A parallel grinding method using the spherical wheel was suggested as a new grinding method. In this method, the wheel axis is positioned at a $\pi$/4 from the Z-axis in the direction of the X-axis. An advantage of this grinding method is that the wheel used in grinding achieves its maximum area, reducing wheel wear and improving the accuracy of the ground mirror surface. In addition, a truing by the CG (curve generating) method was proposed. After truing, the shape of spherical wheel transcribed on the carbon is measured by the Form-Talysurf-120L. The error of the form in the spherical wheel which is the value ${\Delta}x$ and $R{^2}{_y}$ inferred from the measured profile data is compensated by the re-truing. Finally, in the aspherical grinding experiment, the WC of the molding die was examined by the parallel grinding method using the resin bonded diamond wheel with a grain size of ＃3000. A form accuracy of 0.16${\mu}m$ P-V and a surface roughness of 0.0067${\mu}m$ Ra have been resulted.

• 대한기계학회논문집A
• /
• 제39권8호
• /
• pp.759-763
• /
• 2015

레이저 가공 공정은 마스크 없이 전극을 가공할 수 있다는 장점 때문에 우수한 공정들 중의 하나로 제안되고 있다. 본 논문에서는, 서로 다른 열적 물성을 가지는 금속들에 레이저 가공을 수행하였다. 이 금속들은 서로 다른 표면형상, 열영향부, 그리고 재융착층을 나타내었고 이는 열전도도, 끓는점, 그리고 열확산계수에 의존하였다. 또한 재융착층을 제거하기 위하여 초음파 원용 레이저 가공을 적용, 높은 열확산계수를 가지는 재료에서 그 초음파 가진에 의한 표면 품질의 향상을 발견하였다.

• 한국정밀공학회지
• /
• 제26권8호
• /
• pp.55-61
• /
• 2009

Recently, many studies are being conducted to realize high quality polishing technology, but because of high dependence on field experience and insufficient research for ultra-precision polishing technology, it is difficult to establish standardization of polishing conditions. The purpose of this study is to determine high-efficiency superfinishing conditions which are applicable in the field of machining. To achieve this, we have a developed a superfinishing device and conducted a series of polishing experiments for mechanical materials such as SM45C, Brass, Al7075, and Ti, from the perspective of oscillation speed, the rotational speed of the workpiece, contact roller hardness, contact pressure, and feed rate. From the experimental results, it was confirmed that the polishable superfinishing conditions range and efficient feed rate of polishing film can be determined.