• 한국공작기계학회논문집
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• 제10권6호
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• pp.1-7
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• 2001

It is very important to test circular motion accuracy of NC machine tools as it affects all other machines machined by them in industries. In this paper, it has become possible to detect errors of linear displacement of radial directions for circle tar motion accuracy test using newly assembled magnetic type of linear scale so called Magnescale ball-bar system. It has also organized computer program systems using tick pulses come out from computer for getting error motion data at colt start time interval in circular motion test on NC lathe. Error data gotten from test is expressed to plots and analysed to numerics by various statistical treatments.

• 소성∙가공
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• 제5권2호
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• pp.115-121
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• 1996

Recently it is attempted to manufacture gears by various cold forging methods to meet requirements of mass production and uniform qualities. Compared to machined gears cold forged ears reveal higher tooth strength and better surface roughness but they reveal lower geometrical accuracies. Therefore in the present study a series of experiments are performed to investigate relations between geometrical accuracies of dies and billet and those of the final product. The geometrical accuracies of forged gears are considered through functional gear-element tolerances by measuring pitch error profile error lead error radial error tooth thickness and rolling test. Results of the experiments can be summarized as follows: (1) involute spur gears of KS 5(or AGMA7) accuracies can be made,(2) concentricity of die set should be maintained within 0.01mm (3) clearance between the billet and die set should be less than 0.1mm (4) con-centricity and radial runout should be less than 0.08mm and 0.1mm respectively. However it is thought that FEM analysis of elastic/thermal deformations of dies and the billet is necessary for a better understanding of the findings obtained through the present study.

• 한국정밀공학회지
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• 제20권3호
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• pp.187-193
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• 2003

This paper presents an on-machine measurement method of flatness error fur surface machining processes. There are two kinds of on-machine measurement methods available to measure flatness errors in workpieces: i.e., surface scanning method and sensor scanning method. However, motion errors are often engaged in both methods. This paper proposes an idea to realize a measurement system of flatness errors and its rigorous application for estimation of motion errors of the positioning system. The measurement system is made by modifying the straightness measurement system, which consists of a laser, a CCD camera and processing system, a sensor head, and some optical units. The sensor head is composed of a retroreflector, a ball and ball socket, a linear motion guide unit and adjustable arms. The experimental .results show that the proposed method is useful to identify flatness errors of machined workpieces as well as motion errors of positioning systems.

• 대한기계학회논문집A
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• 제36권2호
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• pp.195-201
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• 2012

다양한 소비자의 요구에 따라 가공된 제품을 좀더 신속하고 정확하게 측정할 수 있는 공작기계 내 자동계측장치를 적용하는 사례가 급격히 증가하고 있다. 자동 계측으로 가장 많이 활용되는 접촉식 측정 프로브는 주로 공작물의 가공 원점을 설정하고, 정확한 치수 검사를 통한 불량유무 판정 및 보상가공에 많이 활용된다. 따라서 본 연구에서는 기기상 자동계측장치인 접촉식 측정 프로브를 활용하여 가공된 형상을 신속하고 정확하게 측정하는 방법을 연구하였으며 이를 위하여 가장 많이 활용되는 홀 측정 사이클에 대한 매크로 프로그램을 개발하였다. 또한 측정 시 홀의 진원도 오차에 따라 발생할 수 있는 편심량을 시뮬레이션하여 분석하였으며 본 연구의 신뢰성을 높이기 위하여 기기상에서 개발된 홀 측정 매크로 프로그램을 이용하여 홀플레이트에 대한 측정이 이루어졌으며, 진원도 오차에 따른 편심량을 검증하였다.

• 대한기계학회논문집A
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• 제31권11호
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• pp.1053-1058
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• 2007

Micro-EDM technology (or the manufacture of miniature parts is used to make a micro hole. Two electrode shaping methods, mechanical electrode grinding and WEDG technique, have been studied. In this study, an electrode shaping method by using previously machined hole is introduced in order to obtain an optimal hole-making condition. Key factors such as applied voltage, capacitance, feedrate, and hole-dimension have an influence on the fabricating error of electrode shaping, which are taper ratio of a hole, electrode form accuracy, and electrode surface. Therefore, we try to investigate the optimal fabricating of electrode shaping from various experiments. Results from experiments, it was able to minimize the electrode fabricating error as voltage increases, and also applied feedrate and capacitance decreases.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.380-384
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• 1997

For improving the motion accuracy of hydrostatic table, corrective machining algorithm is proposed in this paper. The algorithm consists of three main processes. Reverse analysis is performed firstly to estimate rail profile from measured linear and angular motion error, in the algorithm. For the next step, correctwe machining information is decided as referring to the estimating rail profile. Finally, motion errors on correctively machined rail are analized by using motion error analysls method proposed in the previous paper. These processes can be rtcrated if the analized motion errors are worse than target accuracy. In order to verify the validity of the algorithm theoretically, motion errors by the estimated rail after corrective machining are compared with motion errors by true rail assumed as the measured value. Estimated motion errors show good agreement with assumed values, and it is confirmed that the algorithm IS effective to acquire the corrective machming information to improve the accuracy of hydrostatic table.

• 한국기계가공학회지
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• 제8권3호
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• pp.1-6
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• 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.

• 한국생산제조학회지
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• 제22권4호
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• pp.735-739
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• 2013

The error motion of a machine tool spindle directly affects the surface errors of machined parts. Spindle motion errors such as three translational motions and two rotational motions are undesirable. These are usually due to the imperfectness of bearings, stiffness of spindle, assembly errors, and external force or unbalance of rotors. The error motions of the spindle need to be reduced for achieving the desired performance. Therefore, the level of error motion needs to be estimated during the design and assembly process of the spindle. In this study, an estimation method for five degree-of-freedom (5 DOF) error motions for a spindle with an angular contact ball bearing is suggested. To estimate the error motions of the spindle, the waviness of the inner-race of bearings and an external force model were used as input data. The estimation model considers the geometric relationship and force equilibrium of the five DOFs. To calculate the error motions of the spindle, not only the imperfections of the shaft and bearings but also driving elements such as belt pulley and direct driving motor systems are considered.

• 한국정밀공학회지
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• 제18권4호
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• pp.97-103
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• 2001

Accuracy of a machined part is determined by the relative motion between the cutting tool and the workpiece. One of the important factors which affects the relative motion is the geometric errors of a machine tool. In this study, firstly, geometric errors are measured by laser interferometer, and the positioning error of each control point selected uniformly on the control surface CAD model can be estimated from th oirm shaping model and geometric error data base. Where a form shaping function is derived from the link of homogeneous transformation matrix. Secondly, control points are shifted to the estimated amount of positioning errors. A new control surface is modeled with NURBS(Non Uniform Rational B-Spline) surface approximation to the shifted control points. By generating tool paths to the redesigned control surface, we reduce the machining error quite.

• 한국정밀공학회지
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• 제26권6호
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• pp.50-58
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• 2009

Micro laser fabrication techniques can potentially be used for the manufacture of microstructures on the thin flat surfaces with large diameter that are frequently used in semiconductor industries. However, the large size of wafers can cause the degraded machining accuracy of the surface because it can be tilted or distorted by geometric errors of machines or the holding fixtures, etc. To overcome these errors the off-line focusing error compensation method is proposed. By using confocal autofocus system, the focusing error profile of machined surface is measured along the pre-determined path and can be compensated at the next machining process by making the corrected motion trajectories. The experimental results for silicon wafers and invar flat surfaces show that the proposed method can compensate the focusing error within the level of below $6.9{\mu}m$ that is the depth of focus required for the laser micromachining process.