• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.567-572
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• 2000

From the experimental study of W-EDM for alloyed steel, the characteristics such as Hand Drum Form and surface roughness have been observed and evaluated for various conditions. In square hole, the increase of IP as to made condition, the calculate high value of surface roughness. Also compare dimensionless square hole with circle hole' graph, In circle hole, if a value of surface roughness IP 6 in a side of circle it show a 0.4${\mu}{\textrm}{m}$ and in IP 8, 0.6${\mu}{\textrm}{m}$, in IP 10, 0.7${\mu}{\textrm}{m}$, in IP 12, 0.8${\mu}{\textrm}{m}$ higher than before. This figure show the surface roughness is higher than before, because a table move in either X-axis or Y-axis in square hole, on the contrary, in circle there table move in X-axis and Y-axis at the same time. hand drum form getting small when wire tension increase 1000gf to 1500gf, at the same working conditions. The smaller of off time, the maller of hand drum form in same condition and same wire tension. but if you compare square hole with circle hole' graph, hand drum form displayed in maintained term of working condision, on the contrary, in case of square hole variation of hand drum form is more increase than a grow of IP

• 대한조선학회논문집
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• 제35권2호
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• pp.51-62
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• 1998

본 연구에서는 공동수조(Cavitation Tunnel) 실험용 모형프로펠러의 5축 가공을 위해 Windows NT와 PC 환경하에서 작동하는 CAD/CAM 시스템을 개발하였다. 본 시스템은 그 성격에 따라 크게 4가지의 모듈로 구성되어 있다. 먼저, 프로펠러 설계를 위해 기존에 사용하고 있던 텍스트 위주의 S/W(Text based S/W)를 그래픽화 하여 통합함으로써 설계의 효율을 향상시켰다. 설계의 결과로 출력되는 점 데이터는 NURBS(Non-Uniform Rational B-Spline) 방법을 이용하여 복합곡면 (Composite Surface)으로 모델링하였고 가공은 황삭, 중삭, 정삭 및 잔삭으로 수행하였다. 각각의 경우에 있어서 공구와 공작물의 충돌 및 간섭을 체크하여 공구경로를 산출하였으며 그것을 역기 구학 해석하여 NC 데이터로 변환하였다. 또한, 가공의 상태를 화면상에서 검증하기위해 공구 및 공작물을 그래픽화하여 NC 데이터를 검증할 수 있도록 하였다. 끝으로 5축 가공의 가공 효율을 최대화하기 본 연구에서는 공동수조 실험용 모형프로펠러의 5축 가공을 위해 Windows NT와 PC 환경하위해 실험을 통하여 최적의 절삭조건을 선정하고 이를 시스템내에 데이터베이스화 함으로써 설계부터 가공까지를 자동으로 수행할 수 있는 시스템으로 구축하였다.

• 한국정밀공학회지
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• 제29권2호
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• pp.129-138
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• 2012

In this study, three types of large scale multi-tasking machine tools together with core technologies involved have been developed and introduced; a multi-tasking machine tool for large scale marine engine crankshafts, a multi-tasking vertical lathe for windmill parts, and a large scale 5-axis machine tool of gantry type. Several special purpose devices has been necessarily developed for the purpose of handling and machining big and heavy workpieces accurately, such as PTD (Pin Turning Device) with revolving ring spindle for machining eccentric crankshaft pins, hydrostatic rotary table and steady rest for supporting and resting heavy workpieces, and 2-axis automatic swiveling head for high-quality free surface machining. Core technologies have been also developed and adopted on their detail design stage; 1) structural design optimization with FEM structural analysis, 2) theoretical hydrostatic analysis for the PTD and rotary table bearings, 3) box-in-box type cross-rail and octagonal ram design to secure machine rigidity and accuracy, 4) constant spindle rpm control against gravitational torque due to unbalanced workpiece.

• 산업공학
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• 제11권2호
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• pp.65-78
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• 1998

The letters of the automobile tire are usually engraved on the side-wall. The shape of the side-wall is a sculptured surface generated by the rotational sweeping of a profile curve. The letters laid on the side-wall are usually designed by a 2-dimensional CAD. It is impossible to machine the letters on the surface accurately by 3-axis NC machining, because the axis of cutter should be tilted to align with the normal vector of the surface. In this case. the degree of freedom for the machine is at least four. This paper describes an idea for tool path generation of a 4-axis machine by using the 2-dimensional CAD data of the letters and the surface of the side-wall. This study includes the following procedures; (1) measuring the profile of the side-wall surface and curve-fitting of the measured points. (2) the 'non-parallel projection' of the letters on the side-wall, and (3) an inverse kinematics of the 4-axis lettering machine. Procedures in this paper are programmed in C-language on Windows95 environment. With a PC based CNC controller and a 4-axis lettering machine. these are tested sucessfully for the practical use.

• 한국산업융합학회 논문집
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• 제26권4_2호
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• pp.605-613
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• 2023

The multi-axis combined machining technology has enabled combined machining, which was difficult. However, the reality is that manufacturing costs are rising due to expensive equipment and there is a shortage of machine operation engineers. The purpose of this research is to present the optimum cutting conditions for the surface roughness when processing the inner diameter of SUS440C, which is an egg material, using a CNC automatic lathe. As a result of measuring the surface roughness, dry machining was the best at R_a0.481㎛ at a spindle speed of 4,000rpm, a feed rate of 0.05rev/min, and a cutting depth of 0.3mm. In wet machining, the highest value was R_a0.317 at a spindle speed of 2,000 rpm, a feed rate of 0.05 rev/min, and a cutting depth of 0.2 mm. The lower the feed rate, the better surface roughness appears. It was found that the feed rate had more influence than the number of revolutions and depth of cut.

• 한국정보처리학회논문지
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• 제7권7호
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• pp.2188-2195
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• 2000

This paper deals with the problem of determining small-bands enclosing a given set of points on the sphere. The small-band is a spherical region, whose boundary is composed of two circles, and which does not contain any great circle. It is a kind of domains that is derived from formalizing the local accessibility problems for 3-axis NC machining into sperical containment problems so as to avoid the grouping. It also can be generated in 4- and 5-axis machine. When a set of points U and the size of a great-band are given, the methods for computing a feasible band and all feasible bands enclosing U in O(n) and O(n log n) time have been suggested, respectively. The methods can be applied into the cases of small bands since the solution region may contain holes. In this paper, we concentrate on the method for determining the smallest small-band enclosing U and suggest an O(n long n) time algorithm, where n is the number of points on the sphere.

• 한국CDE학회논문집
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• 제8권4호
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• pp.278-288
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• 2003

Presented in this paper is a numerical method for calculating the intersection points between Z-map vectors and the tool swept surface for circularly moving filleted-end mills. In numerically controlled(NC) machining simulation for large moulds and dies, a workpiece is frequently approximated as a set of z-axis aligned vectors, called Z-map vectors, and then the machining processes can be simulated through updating the Z-map with the intersection points. Circular motions are typically used for machining the free-form surfaces. For fast computation, we express each of intersection points with a single-variable non-linear equation and calculate the candidate interval in which the unique solution exists. Then, we prove the existence of a solution and its uniqueness in this candidate interval. Based on these properties, we can effectively apply numerical methods to finally calculate the solution of the nonlinear equation within a given precision. Experimental results are given for the case of a TV monitor and the hood of a car.

• 한국정밀공학회지
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• 제21권4호
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• pp.64-71
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• 2004

The growing need for higher precision and productivity in manufacturing industry has lead to an increased interest in computer numerical control (CNC) systems. It is well known fact that the cross-coupling controller (CCC) is an effective method for contouring applications. In this paper, a multi-axis contour error controller (CEC) based on a contour error vector using parametric curve interpolator is introduced. The contour error vector is a vector from the actual tool position to the nearest point on the desired path. The contour error vector is the closest error model to the contour error. The simulation results show that the CEC is more accurate than the conventional CCC for a biaxial motion system. In addition, the experimental results on 3-axis motion system show that the CEC is simply applied to 3-axis motions and contouring accuracy is significantly improved.

• 항공우주시스템공학회지
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• 제12권4호
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• pp.18-25
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• 2018

가공의 정밀도와 난삭재 가공이 요구되는 항공기부품용 공작기계의 헤드프레임 구조는 정밀 고속가공을 위해 경량화 및 절삭력에 의한 변형최소화가 필요하다. 본 논문에서는 고강성 경량화 구조 최적설계를 위해 유한요소해석을 수행하여 초기형상을 설계하였고, 컴플라이언스를 최소화하여 경량, 고강성 및 저진동 구조의 위상 최적화 설계를 수행하였다. 최적화 설계결과 프레임 중량은 17.3% 감소되었고, 최대 처짐량은 0.007 mm 이하, 고유진동수는 30.6% 증가되었다. 구조 정강성은 각 축 방향으로 증가되었고, 동강성은 축에 따라 상반된 결과를 나타내었다. 위상 최적화 설계 구조에서 저진동의 고강성을 갖는 최적화된 구조를 확인하였다.

• 한국레이저가공학회지
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• 제18권4호
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• pp.17-22
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• 2015

In this paper, ablation rate of $Al_2O_3$ ceramics by femtosecond laser fluence is derived with experimental method. The automatic three axis linear stage makes laser optics to move with high spatial resolution. With 10 times objective lens, minimal pattern width of $Al_2O_3$ is measured in the focal plane. Ablated surface area is shown as linear tendency increasing number of machining times with various laser power conditions. Machining times is most sensitive condition to control $Al_2O_3$ pattern width. Also, the linear increment of pattern width with laser power change is investigated. In high machining speed, the ablation volume rate is more linear with fluence because pulse overlap is minimized in this condition. Thermal effect to surrounding medium can be minimized and clean laser process without melting zone is possible in high machining speed. Ablation volume rate decelerates as increasing machining times and multiple machining times should be considered to achieve proper ablation width and depth.