• 한국기계가공학회지
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• 제13권1호
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• pp.85-91
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• 2014

The rotation of a spindle unit must be accurate for high-quality machining and to improve the quality of the machine tools. Therefore, the proper measurement of the rotation accuracy and ensuring a proper analysis are very important. Separate processes are necessary because spindle errors and roundness errors associated with the test balls can both factor into the measured rotation error values. We used three methods to discern test ball errors and analyzed which could be deemed as the most proper technique in a test of the rotation accuracy of the main spindle of a machine tool.

• 한국정밀공학회지
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• 제16권10호
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• pp.45-52
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• 1999

The online realtime positioning error compensation system 'SKY-PACS' is developed to correct geometric errors, thermal errors and tool deflection errors induced by cutting forces on the vertical machining center. 'SKY-PACS' communicates position commands and position compensation signals with the CNC controller at 100Hz, which is CNC control frequency. So the compensation procedure can be applied during axis movement. Using 'SKY-PACS', Maximum 1 axis positioning accuracy was corrected from 5{\mu}m$ to 2{\mu}m$and the squareness error of X-Y table was corrected from 51{\mu}m$/m to below 4{\mu}m$/m. The error compensation under the cutting condition is carried out by ISO10791-7. And the measurement of test-pieces shows that the roundness is corrected rom 8{\mu}m$ to below 5{\mu}m$.

• Design & Manufacturing
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• 제8권1호
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• pp.40-44
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• 2014

As a rotating machine element, plastic gears are more and more widely used in such as industrial machine element, since plastic gear is lighter, higher wear-resistance, and higher vibration absorbing ability than metal gears. When operating plastic parts, tooth breakage and fatigue life shortened due to increasing number of applying load and tooth flank temperature rising, such that accuracy of plastic gears is divided from allowable range to cause vibration and noise. On this study, a internal plastic gears are developed which improved the filling balance molding process by a new injection mold structure. The new mold structure called HR3P(hot runner type 3plate mold). As the result from this studies, we obtained a very accurate roundness internal gears by using design of experiment.

• 한국공작기계학회논문집
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• 제13권3호
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• pp.61-67
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• 2004

In micro hole punching process the burr occurs inevitably, but the burr must be minimized in order to improve the quality and accuracy of the product. In this study, magnetic field-assisted polishing technique is applied to remove the burr which exists in nozzles for ink-jet printer head and proved to be a feasible for deburring by experiment. The deburring characteristics of sheet metals was investigated changing with polishing time and magnetic abrasive size. After the deburring, the burr size has remarkably reduced and roundness of the hole also has improved.

• 한국정밀공학회지
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• 제12권7호
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• pp.5-18
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• 1995

1775년에 Steam Engine의 Cylinder를 제작하기 위하여 Horizontal Boring Machine이 영국의 John Wikinson에 의해서 제작되었다. 그것이 인류가 제작한 금속을 절삭할 수 있는 최초의 공작기계라고 기록되고 있다. 그 때의 공작기계 정밀도는 얼마나 되었을까\ulcorner Tolerance와 Roundness등은 얼마나 되었을까\ulcorner 라는 의문과 현재 실현할 수 있는 공작기계의 정밀도는 얼마나 될 것인가를 생각하면서 오늘날의 공작기계가 있게 한 그 동안의 과정과 기술의 발전을 더듬어 보아야 할 것이다. 1983 CIRP Meeting에서 Taniguchi교수가 특색있는 Key-Note Paper를 발표하였다. 그가 발표한 내용은 Fig 4-1에서 볼 수 있는 바와 같이 도달할 수 있는 가공정밀도를 보통, 정밀, 초정밀의 세가지로 나누어 1900년과 2000년 사이에 변천하는 과정을 정리하였다. 여기서 정밀도라 함은 Dimensional Accuracy로서 Tolerance(Length, Diameter)를 말한다.

• 한국해양공학회지
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• 제8권1호
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• pp.131-143
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• 1994

The BTA(boring and trepanning association) deep hole machining has an increasing demands because of its wide applications and its good productivity. The main feature of the BTA tools is that the tool cutting edges are unsymmetrically located on the boring head. This provides a stabilizing cutting force resultant necessary for self guidance of the boring head. The BTA tools are capable of machining for having a large length to diameter ratio in single pass. A study of the accuracy and surface finish of holes produced would reveal quite useful information regarding the process. This study deals with the experimental results obtained during BTA machining on SM55C, SM45C steel under differnt machining conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1517-1521
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• 2007

On this study, technical aspects were reviewed to drill a series of micro holes (${\phi}$0.10) over 200 within a few micron tolerance in diameter and position on the stainless steel material. Dedicated tools & jigs were designed and manufactured and optimum cutting conditions were found. On this micro hole drilling process, guide drill and step feeding were applied to help chip discharge, prevent drill breakage and finally improve the accuracy of positioning and roundness. The processing results indicated that most holes are distributed within a few micron tolerance in diameter and position intervals.

• 소성∙가공
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• 제7권4호
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• pp.393-399
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• 1998

For minimizing wall thickness thinning of circular shells, a new stamping technology, the deep draw-ing process combined with ironing is approached and investigated. The design requirements for the deep drawing shells are to keep the optimum wall thickness with max. 10 percent thickness thinning of the initial blank thickness, to make uniform thickness strain distribution for the wall of circular shell and to improve the shape accuracy for the roundness and concentricity. In order to check the validity and effectiveness of proposed work, a sample process design is applied to a circular shell needed for a 4multi-stepped deep drawing. Through experiments, the variations of the thickness strain distribution in each drawing process are observed. Also a series of experiments are performed to investigate optimum process variables such as the geometry of tooling, radius and drawing rate. In particular, the advantage of current approach with ironing is shown in contrast to the conventional deep drawing process. From the results of proposed method, the optimum value of process variables are obtained, which contribute more uniform thickness strain distribution and better quality in the drawn product.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.329-333
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• 2003

In micro hole punching process the burr occurs inevitably, but the burr must be minimized in order to improve the quality and accuracy of the product. In this study, magnetic field assisted polishing technique is applied to remove the burr which exists in nozzles for ink-jet printer head and proved to be a feasible for deburring by experiment. The deburring characteristics of sheet metals was investigated changing with polishing time. After the deburring, the burr size has remarkably reduced and roundness of the hole also has improved.

• 한국공작기계학회논문집
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• 제11권1호
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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.