• 한국정밀공학회지
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• 제29권8호
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• pp.863-872
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• 2012

The squareness measurement of driving axes of a machine tool is very important to evaluate the performance of the machine. Laser interferometer measurement system is one of the most reliable equipment to measure the squareness. However, squareness measurement using laser system with an optical square result in restriction of straightness optics setup and Abbe's offset. This offset combines with angular errors during the motion of an axis to cause Abbe's error. In addition, the difficulty in optical square setup causes restriction of other optics and limitation of measurable range. In this paper, mathematical approaches are presented to eliminate the Abbe's error and to estimate squareness for full range by using the best fit of straightness data measured without an optical square. Experiments for squareness measurement of 3 axis machine tool were conducted and the proposed techniques were used for squareness evaluation with elimination of Abbe's error and squareness estimation for the full travel range.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.287-288
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• 2006

This paper introduces an approach of method to compensate accuracy error of diagonal direction. The measurement of squareness error is an important parameter in performance test of two axis Linear Motor and this exerts influence on accuracy error of diagonal test. However, previous knowledge management approaches are limited in deviation measurement of optical axis or restrictive elements of diagonal measurements using laser interferometer. But this proposed method calculated diagonal accuracy error which was occurred by squareness error and compensated squareness error using orthogonal correction method of PMAC. From this result, diagonal accuracy error is significantly reduced. This experimental results show that geometric error of squareness error is easily corrected by dynamic coordinate correction.

• 한국정밀공학회지
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• 제33권4호
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• pp.295-301
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• 2016

The out-of-squareness is one of the error sources that affect the positioning accuracy of machine tools and coordinate measuring machines. Laser interferometer is widely used to measure the position and angular errors, and can measure the squareness using an optical square. However, the squareness measurement using the laser interferometer is difficult, as compared to other errors due to complicated optics setup and Abbe's error occurrence. The effect of out-of-squareness mainly appears at the face-diagonal of the movable plane. The diagonal displacements are also affected by the position dependent geometric errors. In this study, the squareness estimation techniques via diagonal displacement measurement using the laser interferometer without an optical square were proposed. For accurate estimation and measurement time reduction, the errors selected from proposed discriminant were measured. Discrepancy between the proposed technique with the laser interferometer (with an optical square) result was $0.6{\mu}rad$.

• 한국정밀공학회지
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• 제19권4호
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• pp.124-131
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• 2002

In this paper, an extended volumetric error model considering backlash in a three-axis machine tool was proposed and utilized for calculating the volumetric error of the machine tool at any position in three-dimensional workspace. Backlashes are interrelated; i.e. the angular backlash affects the straightness errors which then affect talc calculated squareness errors. Therefore, a new concept was introduced to define the backlash of squareness errors to incorporate the backlash of squareness error into the volumetric error, and the characteristics of the backlash of squareness error were investigated. The effects of backlash errors were assessed, by experiments. for 21 geometric errors of a machine tool. The backlash error was shown to be one of the systematic errors of a machine tool. And a generalized volumetric error model formulator for three-axis machine tools was developed, which allowed us to formulate machine tool synthesis error models far all possible machine tool configurations only with machine tool topology information. Based on these volumetric error model and model formulator, a computer-aided volumetric error analysis system was developed for a three-axis machine tool in this paper. Then the volumetric error at an arbitrary position can be obtained, and displayed in a three-dimensional graphic form.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.676-680
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• 2000

In this paper, an extended volumetric error model considering backlash in a three-axis machine tool was proposed and utilized for calculating the volumetric error of the machine tool at any position in three-dimensional workspace. Backlashes are interrelated; i.e. the angular backlash affects the straightness errors which then affect the calculated squareness errors. Therefore, a new concept was introduced to define the backlash of squareness errors to incorporate the backlash of squareness error into the volumetric error, and the characteristics of the backlash of squareness error were investigated. The effects of backlash errors were assessed, by experiments, fur 21 geometric errors of a machine tool. The backlash error was shown to be one of the systematic errors of a machine tool. Based on this volumetric error model, a computer-aided volumetric error analysis system was developed for a three-axis machine tool in this paper. Then the volumetric error at an arbitrary position can be obtained, and displayed in a three-dimensional graphic form.

• 한국재료학회지
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• 제14권9호
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• pp.655-658
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• 2004

Lithium ferrites are a low-cost material which have been prominent in the high frequency core industry because of their excellent temperature performance and high squareness ratio. In order to develope the lithium ferrites with the high squareness and low coercive force, the ferrites of $Li_{0.48}Bi_{0.02}Ni_{0.04}Fe_{2.46-x}O_4$ were investigated the by varying composition, temperature and frequency. Electric loss of the Li-ferrite was lowered with the substitution of $Mn_{2}O_3$. The addition of $Mn_{2}O_3$ increased the magnetic induction (Bm&Br) but decreased the coercive force (Hc) and the squareness ratio (R=Br/Bm). Also, the Br value was stable at environmental temperature variation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.307-308
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.849-850
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• 2012

• 한국자기학회지
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• 제9권5호
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• pp.234-238
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• 1999

각종 microwave용 통신기기 소자 및 고주파용 memory 소자로 사용하기 위해서 각형비가 크고 보자력이 작은 lithium ferrite를 개발하고 물리적인 특성을 조사하기 위하여 Li0.48-0.5xBi0.02Ni0.04ZnxFe2.46-0.5xO4의 조성식을 갖는 시편을 제조하였다. ZnO을 첨가하여 변화시킴에 따라 잔류자기(Bm)가 증가하고 보자력(Hc)이 낮아졌으나 각형비 R은 감소하였다. 105$0^{\circ}C$에서 소결한 시편의 경우 R=0.82, Hc=1.8Oe로 나타났고 110$0^{\circ}C$에서 소결한 시편의 경우 R=0.75 및 Hc=1.70Oe인 값을 얻었다. Tc는 463$^{\circ}C$로 측정되었고 주변온도 변화에 대한 Br값의 변화가 매우 안정된 0.09~0.11 값으로 나타났다.

• 한국자기학회지
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• 제4권2호
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• pp.89-93
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• 1994

Mg-페라이트에 있어서 B-H hysteresis loop 특성에 미치는 소결체의 밀도, 내부 응력, 입자 크기의 영향을 조사하였다. 밀도가 증가함에 따라서 보자력은 감소하였으며 각형비는 증가 하였다. 보자력은 내부 응력에 매우 의존적이었으며 시편 내부에 응력이 존재할때 보자력은 1.95 [Oe]에서 4.35[Oe]로 증가하였다. 그러나 각형비는 큰 차이가 없었다. 입자 크기가 6-11[um] 범위 내에서의 보자력 및 각형비는 입자 크기에 의존성을 갖지 않았다.