• 인지과학
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• 제29권1호
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• pp.17-38
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• 2018

본 연구의 목적은 도구를 사용하더라도 닿지 않는 거리에 놓인 대상에서 도구 길이에 따라 지각된 거리가 상이한 정도로 압축되는지, 그리고 가리키는 대상에서만 도구 길이에 따라 지각된 거리가 압축되는지를 검증하는 것이다. 자기중심적 거리를 측정한 실험 1은 도구를 사용하여 닿지 않는 거리에 놓인 대상에서도 도구 길이가 길어질수록 대상까지의 거리를 더 가깝게 지각한다는 것을 발견하였다. 자기중심적 거리를 측정한 실험 2는 가리키는 대상과 가리키지 않는 대상이 시야에 공존할 때 도구 길이가 가리키지 않는 대상까지의 거리 지각에 영향을 미치지 않는다는 것을 발견하였다. 실험 3은 실험 2와 동일한 환경에서 표적과 측정 대상 사이의 거리인 대상중심적 거리를 측정하여 도구 길이가 표적의 거리지각에만 영향을 미친다는 것을 발견하였다. 이와 같은 실험 결과는 도구를 사용하여 닿을 수 없는 거리에서도 지각된 거리의 압축 현상이 나타나며 이와 같은 지각된 거리의 압축 현상은 가리키는 대상에 국한된다는 것을 시사한다.

• International Journal of CAD/CAM
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• 제8권1호
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• pp.45-53
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• 2009

As the point sampling technology evolves rapidly, there has been increasing need in generating tool path from dense point set without creating intermediate models such as triangular meshes or surfaces. In this paper, we present a new tool path generation method from point set using Euclidean distance fields based on Algebraic Point Set Surfaces (APSS). Once an Euclidean distance field from the target shape is obtained, it is fairly easy to generate tool paths. In order to compute the distance from a point in the 3D space to the point set, we locally fit an algebraic sphere using moving least square method (MLS) for accurate and simple calculation. This process is repeated until it converges. The main advantages of our approach are : (1) tool paths are computed directly from point set without making triangular mesh or surfaces and their offsets, and (2) we do not have to worry about no local interference at concave region compared to the other methods using triangular mesh or surface model. Experimental results show that our approach can generate accurate enough tool paths from a point set in a robust manner and efficiently.

• 한국생산제조학회지
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• 제7권5호
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• pp.127-133
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• 1998

This research intends to gain the sight for the qualitative characteristics of precision cutting by using the CNC lathe with a mono-crystal diamond(MCD) and a poly-crystal diamond(PCD) tool on the cutting distance. In case of an MCD tool, as the cutting distance increases, the surface roughness becomes worse and the standard deviation of surface roughness is small. In case of a PCD tool, as the cutting distance increases, the surface roughness becomes stable with a large standard deviation. The cutting force ratio(Ft/Fn) decreases as the nose radius increases and the decreasing ratio becomes larger for small nose radius.

• 한국생산제조학회지
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• 제7권5호
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• pp.15-28
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• 1998

Recently may investigations have been studied on the high-speed machining by using machine tools. A CNC machine tool makes some tool path errors caused by software acceleration/deceleration. The faster a cutting feedrate is, the bigger the tool path errors are. Some known methods reduce these kinds of errors, but they make the total cutting time increased. This paper presents a feed-forward algorithm that can be generated by distorting the original tool path, and reduces the tool path errors and the total cutting time. The algorithm to generate a new tool path is represented as following; 1)calculating each distance of software acceleration/deceleration between two adjacent blocks, 2) estimating the distorted distance which is the adjacent-ratio-constant(k1, k2) multiply the distance of software acceleration/deceleration, 3) generating a 3-degree Bezier curve approximating the distorted tool path, 4) symmetrically transforming the Bezier curve about the intersection point between two blocks, and 5) connecting the transformed Bezier curve with the original tool path. The algorithm is applied to FANUC 0M. The study is to promote the high-precision machining and to reduce the total cutting time.

• 한국공작기계학회논문집
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• 제14권5호
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• pp.13-20
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• 2005

Micro EDM process is generally used for machining microholes, cavities, and three dimensional shapes. For machining micro structures, first of all, micro tool electrode is indispensable and WEDG system is proposed for tool fabrication method. When using WEDG, its machining characteristics are highly affected by many EDM parameters such as applied voltage, current, rotation speed, capacitance, and pulse duration. Therefore, the design of experiment is introduced to fully understand the effect of the EDM parameters on machining tool electrode. And an attempt has been made to develop the mathematical model for predicting the size of the tool electrode by calculating spark distance. The suggested model was verified with experiment and predicted working gap distance is in good accord with the measured value.

• 한국생산제조학회지
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• 제22권1호
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• pp.85-91
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• 2013

The machinability of wear-resistible tungsten carbides and the tool wear behavior in machining of V30 and V50 tungsten carbides using PCD (Poly Crystalline Diamond) cutting tool was investigated to understand machining characteristics. This material is one of the difficult-to-cut materials in present, but their usage has been already broadened to every commercial applications such as mining tools, and impact resistant tools etc. Summary of the results are as follows. (1) Tool wear progression of PCD tools in turning of wear-resistible tungsten carbides were observed specially fast in primary cutting distance within 10m. (2) Three components of cutting resistance in this research were different in balance from the ordinary cutting such as that cutting of steel or cast iron. Those were expressed large value by order of thrust force, principal force, feed force. (3) If presume from viewpoint of high efficient cutting within this research, a proper cutting speed was 15m/min and a proper feed rate was 0.1mm/rev. In this case, it was found that the tool life of PCD tool was cutting distance until 230m approximately. (4) In cutting of wear-resistible tungsten carbides such as V30 and V50, it was recognized that the tool wear rate of V30 was very fast as compared with V50. (5) When the depth of cut was 0.1mm, there was no influence of the feed rate on the feed force. And the feed force tended to decrease as the cutting distance was long, because the tool was worn and the tool edge retreated. (6) It was observed that the tungsten carbides were adhered to the flank.

• 한국생산제조학회지
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• 제9권2호
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• pp.66-71
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• 2000

Laser induced surface hardening of Tool steel(STC5) can be achieved either with or without surface melting. In trans-formation hardening as the surface is heated to a temperature below its melting point and is rapidly cooled solidified microstructures are usually much finer and stronger than those of the base matals. For this reason surface modification of tool steel by YAG laser irradiation has been studied as a function of processing parameters such as power density pulse width defocusing distance and molten depth. The high energy density changes and refines the microstructure of the near surface layer. In the case of beam passes martensite formed in the melt zone exhibited very high vickers hardness values. Molten depth and width depend on defocusing distance and energy of black color painting is more absorptive than other color painting.

• 한국정밀공학회지
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• 제32권8호
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• pp.699-704
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• 2015

Laser-assisted machining has shown its potential to significantly improve product quality and reduce manufacturing costs; additionally, laser-assisted turning (LAT) and laser-assisted milling (LAM) have been studied by numerous researchers. A research study on the determination of the distance between the laser heat source and the tool for laser-assisted machining, however, has not yet been attempted; we conducted such an analysis by using a finite-element method and heat-transfer equation. The results of this analysis can be used as a reference for the determination of the distance between the laser heat source and the tool for laser-assisted machining.

• 한국정밀공학회지
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• 제28권12호
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• pp.1366-1371
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• 2011

In ultra precision machining, it is necessary to adjust the horizontality and reference position of a workpiece in a noncontact manner. For this, a simple process by measuring impedance between a tool tip and a workpiece which are connected to impedance analyzer is proposed. As the distance between the tool and the workpiece gets closer, the reduction rate of impedance becomes higher over all frequency ranges. By setting threshold value of impedance reduction rate at specific frequencies through preliminary experiments, the distance between the tool and the workpiece can be predicted and it directly enables us to horizontalize the workpiece and to set the tool to the desired reference position.

• International Journal of CAD/CAM
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• 제7권1호
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• pp.51-60
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• 2007

This paper presents an algorithm of optimal cutting tool selection for machining of the point-based surface that is defined by a set of surface points rather than parametric polynomial surface equations. As the ball-end and fillet-end mills are generally used for finish machining in a 3-axis computer numerical control machine, the algorithm is applicable for both cutters. The optimum tool would be as large as possible in terms of the cutter radius and/or corner radius which maximise (s) the material removal rate (i.e., minimise (s) the machining time), while still being able to machine the entire point-based surface without gouging any surface point. The gouging are two types: local and global. In this paper, the distance between the cutter bottom and surface points is used to check the local gouging whereas the shortest distance between the surface points and cutter axis is effectively used to check the global gouging. The selection procedure begins with a cutter from the tool library, which has the largest cutter radius and/or corner radius, and then adequacy of the point-density is checked to limit the accuracy of the cutter selection for the point-based surface within tolerance prior to the gouge checking. When the entire surface is gouge-free with a chosen cutting tool then the tool becomes the optimum cutting tool for a list of cutters available in the tool library. The effectiveness of the algorithm is demonstrated considering two examples.