• 한국산업융합학회 논문집
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• 제10권4호
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• pp.195-200
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• 2007

These days, various and complex threads are developed, so it is necessary to develop the cutting a thread sensors for checking a cut thread in severe environment and it is very important to evaluate the quality of the cutting a thread sensors. The analysis of variance(ANOVA) method is very useful method on the quality evaluation field. In this study, the quality is evaluated by one way layout ANOVA method with the surface roughness data. The experiment is carried out by 3 sensors and the result show that the sensors have the good quality in precision.

• Journal of Welding and Joining
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• 제21권5호
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• pp.525-533
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• 2003

The dimensional accuracy and global roughness between successive layers of VLM-s, which is a new rapid prototyping process using hotwire cutter and EPS foam, depend significantly on the operating parameters of hotwire cutter. In the present study, the effect of cutting angle on the kerf width and edge shape in hotwire cutting of EPS foam for the case of single-sloped cutting with one cutting angle was investigated. Through single-sloped cutting tests, the modified relationship between kerf width and effective heat input, considering the effect of the cutting angle, and the relationship between the melted area and the cutting angle were obtained. In order to investigate the effect of cutting angles on the thermal field in EPS foam, transient heat transfer analyses using single-sloped volumetric heat flux model and locally-conformed mesh were performed. Through the comparison between experimental and numerical results, it was shown that the proposed analysis model is needed to estimate the three-dimensional temperature distribution of the EPS foam for the case of single-sloped hotwire cutting.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.279-284
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• 2000

The object of this paper is to evaluate the chip breakability using the experimental equation of surface roughness, which is developed in turning by an orthogonal array method. L$\sub$9/(3$^4$) orthogonal array method, one of fractional factorial design has been used to study effects of main cutting parameters such as cutting speed, feed rate and depth of cut, on the surface roughness. The evaluation of chip breakability is used the chip breaking index(C$\sub$B/), non-dimensional parameter. And the analysis of variance (ANOYA)-test has been used to check the significance of cutting parameters. Using the result of ANOYA-test, the experimental equation of chip breakability, which consists of significant cutting parameters, has been developed. The coefficient of determination of this equation is 0.866.

• 대한산업공학회지
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• 제22권4호
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• pp.741-751
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• 1996

The three dimensional cutting-stock problem is to maximize the total value of pieces which are smaller cubics-cut from a original cubic stock. This paper suggests a method to maximize the total value of different size cut pieces using the orthogonal non-guillotine cut technique. We first formulated a zero-one integer programming, then developed a Lagrangeon relaxation method far the problem. The solutions were given by using a brunch-end-bound technique associates with Lagrangean relaxation, which guarantees an optimal solution.

• 대한기계학회논문집A
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• 제24권8호
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• pp.2123-2130
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• 2000

Radial immersion ratio is an important factor to determine the threshold in face milling and should be estimated in process for automatic force regulation. In this paper, presented is a method of on-line estimation of the radial immersion ratio using cutting force. When a tooth finishes sweeping, sudden drop of cutting forces occurs. This force drop is equal to the cutting force that acts on a single tooth at the swept angle of cut and can be obtained from cutting force signal in feed and cross-feed direction. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the swept angle of cut is a function of the swept angle of cut and the ratio of radial to tangential cutting force. In the research, it is found that the ratio of radial to tangential cutting force is not affected by cutting conditions and axial rake angle. Therefore, the ratio of radial to tangential cutting force determined by just one preliminary experiment can be used regardless of the cutting conditions. Using the measured cutting force and predetermined ratio, the radial immersion ratio is estimated. Various experiments show that the radial immersion ratio and instantaneous ratio of the radial to tangential direction cutting force can be estimated very well by the proposed method.

• 한국정밀공학회지
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• 제14권3호
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• pp.75-81
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• 1997

Automatic monitoring the cutting state is one of the important problems to increase the reliability of modern machining processes. In this study, cutting force signals were used in order to monitor the tool wear and fracture in the turning process. Turning experiments were performed using cemented carbide insert tools(K20) and STS304 steel as a workpiece. Cutting force signal characteristics and histogram analysis method were used to recognize the cutting states. It was found that tool wear and fracture can be diagnosed from the cutting force signal coefficient of variation(C.V.) and histogram analysis.

• 한국공작기계학회논문집
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• 제15권2호
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• pp.73-80
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• 2006

This paper describes a analysis on the chip thickness model required for cutting force simulation in ball-end milling. In milling, cutting forces are obtained by multiplying chip area to specific cutting forces in each cutting instance. Specific cutting forces are one of the important factors for cutting force predication and have unique value according to workpiece materials. Chip area in two dimensional cutting is simply calculated using depth of cut and feed, but not simply obtained in three dimensional cutting such as milling due to complex cutting mechanics. In ball-end milling, machining is almost performed in the ball part of the cutter and tool radius is varied along contact point of the cutter and workpiece. In result, the cutting speed and the effective helix angle are changed according to length from the tool tip. In this study, for chip thickness model analysis, tool and chip geometry are analyzed and then the definition of chip thickness and estimation method are described. The resulted of analysis are verified by compared with geometrical simulation and other research. The proposed chip thickness model is more precise.

• 한국결정성장학회지
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• 제24권6호
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• pp.274-278
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• 2014

가공정밀도 요구특성의 지속적인 향상에도 불구하고, 공작기계와 절삭공구를 이용한 절삭가공공정에서의 채터진동은 아직도 개선의 여지가 많이 남아있다. 특히, 더욱 고속화, 고정밀화 되고 있는 가공현장에서 채터진동의 효과적인 감소대책에 대한 다양한 연구가 필요하다. 본 연구에서는 이러한 문제점을 해결하기 위해 고정밀 공구동력계를 이용한 실시간 절삭력 측정과 유한요소해석 방법을 이용해 사용 빈도와 활용이 매우 큰 터닝센터(turning center)에서 폭넓게 적용되고 있는 3종의 절삭공구 툴링에서의 채터진동 특성을 평가하여, 공구형상 및 툴링 특성에 따른 채터진동과의 상관성을 연구하고, 향후 채터진동 저감형 공구개발을 위한 근간 기술자료로 활용코자 한다.

• International Journal of Precision Engineering and Manufacturing
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• 제6권1호
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• pp.65-72
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• 2005

Drilling process is one of the most common, yet complex operations among manufacturing processes. The performance of a drill is largely dependent upon drilling forces, Many researches focused on the effects of drill parameters on drilling forces. In this paper, an effective theoretical model to predict thrust and torque in drilling is presented. Also, with the predicted forces, the stress analysis of the drill tool is performed by the finite element method. The model uses the oblique cutting model for the cutting lips and the orthogonal cutting model for the chisel edge. Thrust and torque are calculated analytically without resorting to any drilling experiment, only by tool geometry, cutting conditions and material properties. The stress analysis is performed by the commercial FEM program ANSYS. The geometric modeling and the mesh generation of a twist drill are performed automatically. From the study, the effects of the variation of the geometric features of the drill and of the cutting conditions of the drilling on the drilling forces and the stress distributions in the tool are calculated analytically, which can be applicable for designing optimal drill geometry and for improving the drilling process.

• 한국기계가공학회지
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• 제5권4호
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• pp.59-64
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• 2006

High Speed Machining(HSM) reduces machining time and improves surface accuracy because of the high cutting speed and feedrate. Development of HSM makes it allowable to machine difficult-to-cut material and use small-size-endmill. It is however limited to cutting condition and tool material. In the machining operation, it is important to check main parameter of tool life and select optimal cutting condition because tool breakage can interrupt progression of operation. In this study, cutting parameters are determined to 3 factors and 3 levels which are a spindle speed, a feedrate and a width of cut. Experiment is designed to orthogonal array table for L9 with 3 outer array using Taguchi method. Also, it is proposed to inspect significance of the optimal factors and levels by ANOVA using average of SN ratio for tool life. Finally, estimated value of SN ratio in the optimal cutting condition is compared with measured one in the floor shop and reduction of loss is predicted.