• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.1
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• pp.95-103
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• 2015

This paper presents the effects of the tool shape on the geometrical characteristics of flat end-milled side walls. A tool shape is characterized by such parameters as helix angle, number of cutting edges, and diameter. The geometrical characteristics of the side walls are represented by the surface profiles in the feed and axial directions, which are orthogonal to each other. The geometrical defects in each direction are estimated based on the instantaneous apparent cutting areas, which are represented by the interference area between the tool and workpiece and that between the cutting edge and workpiece. It is confirmed that a geometrical defect in the feed direction is formed when the tool leaves the workpiece and the curvature of the tool path changes. Defects in the axial direction are also found in the side walls, except for the defect zone in the feed direction. An up-cut using an end-mill with a steeper helix angle, a greater number of cutting edges, and a smaller diameter are thus found to improve the geometrical accuracy of end-milled side walls.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.48-53
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• 2010

5-axis CNC machining now is getting popular because it can deal with complex shapes such as impeller, turbine blade and propeller without additional equipment or process, proving a set of various tool orientations. CAM software related to 5-axis machining is being developed quickly so that users can take advantage of potential capacities of 5-axis machine tools. However, only a few researches can be found in the area of control strategy development for 5-axis machining. This paper proposes a 5-axis cross-coupling control system based on a novel tool orientation error model. The proposed tool orientation error model provides accurate information on the tool orientation error in real time, which in turn enables directly controlling the tool orientation accuracy. The proposed control system also employs a contour error model to calculate the contour error and reflect it in the control as well. The accuracy of the proposed tool orientation error model is verified and the performance of the 5-axis cross-coupling control system in terms of both contouring and tool orientation accuracy is evaluated through computer simulations compared with existing 5-axis control systems.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.2001-2011
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• 1993

This study deals with the machining of sculptured surfaces on 5-axis CNC milling machine with end mill cutter. The study (I) has the following contents. In 5-axis CNC milling, CL-data consist of CC-data and cutter axis direction vector at the CC-point. Thus, in machining of the sculptured surface on 5-axis CNC milling machine, determination of the direction vector of the milling cutter is very important. The direction vector is obtained by the fact that bottom plane of the milling cutter must not interfere with the free-form surface being machined. The interference is checked by the z-map method which can be applied in all geometric types of the sculptured surfaces. After generating NC part programs from 5-axis post-processing algorithms, sculptured surfaces were machined with 5-axis CNC milling machine (CINCINNATI MILACRON, 20V-80). From these machining tests, it was shown that the machining of the free-form surfaces on 5-axis CNC milling machine with the end mill has smaller cusp heights and shorter cutting time than on 3-axis CNC milling machine with the ball-end mill. Thus, 5-axis CNC end milling was effective machining method for sculptured surfaces. The study (II) deals with the prediction of cusp height and the determination of tool path interval for the 5-axis machining of sculptured surfaces on the basis of study(I).

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.2012-2022
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• 1993

For the machining of the sculptured surfaces on 5-axis CNC milling machine, the milling cutter direction vector was determined in the study (I) with 5-axis post-processing. Thus, it was possible to cut the sculptured surfaces on five-axis CNC milling machine with the end mill cutter. Then, for smooth machined surfaces in five-axis machining of free-from surfaces, this study develops an algorithm for prediction of cusp heights. Also, it generates tool path such that the cusp heights are constrained to a constant value or under a certain value. For prediction of the cusp height between two basis points, a common plane, containing the line crossing two basis points and the summation vector of two normal vectors at two basis points, is defined. The cusp height is the maximum value of scallops on the common plane after end mill cutter passes through the common plane. Sculptured surfaces were machined with CINCINNATI MILACRON 5-axis machining center, model 20V-80, using end mill cutter. Cusp heights were verified by 3-dimensional measuring machine with laser scanner, WEGU Messtechnik GmbH.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.161-167
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• 1996

In five-axis milling, optimal CL-data (cutter location data) should be generated to have advantages over three-axis milling in terms of accuracy and efficiency. This paper presents an algorithm for generating collision-free CL-data for five-axis milling using potential energy method. By virtually charging the cutter and part surfaces with static electricity, global collision as wells as local interference is eliminated. Additionally, machining efficiency is improved by minimizing the curvature difference between the part surface and tool swept surface at a CC-point (cutter contact point) simultaneously.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.189-189
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• 2004

본 논문은 CNC 밀링머신을 이용한 절삭가공 등 2축시스템의 위치제어 시스템을 대상으로 한다. 기존의 제어방식은 크게 독립축제어와 상호결합제어로 분류할 수 있다. 독립축제어는 두 축의 통합된 운동을 각각의 독립된 축에 대한 추적제어를 수행하여 원하는 공구경로의 위치 정밀성을 향상시키고자 하는 것이고, 상호결합제어는 지령경로에 대한 추적성능보다는 현재의 윤곽오차를 감소시키는 방향으로 제어입력을 인가하여 가공윤곽의 오차를 감소시키는데 주목적이 있다. 또한 최근의 작업공정의 고속화 경향은 윤곽오차를 감소시키면서도 추적성능이 우수한 제어방식을 요구하고 있다.(중략)

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.5
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• pp.391-399
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• 2017

This paper presents the effects of the cutting speed and feed rate on the axial shape of flat end-milled down cut side walls. Experiments were performed using the cutting speed, tool diameter, and feed per tooth as variables, and the thrust force and axial shape were measured as the experimental results. The results of this study confirmed that a smaller feed per tooth, which is proportional to the value obtained by dividing the feed rate by the cutting speed, results in a higher axial shape accuracy. In addition, the axial shape can be simplified to a form in which two straight lines having different slopes meet at a singular point. Therefore, it was concluded that the shape accuracy could easily be estimated during the operation and improved by adjusting the feed per tooth.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.114-123
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• 1998

In the end milling process, the information of the surface errors plays an important role in adaptive control systems for precision machining. As the measuring accuracy of the surface errors directly matches the control's, it is an important factor for evaluating the performance of the system. In order to obtain the surface errors, the prediction using the cutting force, torque, motor power etc. is frequently practiced owing to the easiness in measurement. In the implementation of the prediction, the information on the cutting depths make it concrete and precise. Actually the axial depth of cut limits the range of the calculation. In general, it is not easy to know the cutting depths due to irregular shape of workpieces, inaccurate positioning of them on the table of machine tool, and machining error in the previous cutting. In addition to, even if cutting depths are informed, it is difficult to match the individual position of the cutter on the varying shape of the work material. This work suggests an algorithm estimating the cutting depths based on cutting force and makes it precise to predict the surface error. The proposed algorithm can be applied in more extensive cutting situations, such as presence of the tool wear, change of the work material hardness, etc.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.19-26
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• 1997

The manufacture of an impeller typically requires the 5-axis CNC machining, since the impeller is usually under working conditions such as high speed, high temperature, and high pressure. Thus, this study contributes to development of an exclusive CAM system for effective 5-axis CNC machining of a ruled surface type impeller. In this study, the sampled impeller is made of blades and a body and the blade consists of ruled surfaces between hub curve and shroud curve. In the post processing for 5-axis NC part program, the cutter axis direction vector is the straighten vector on ruled surface. The position of ball center in ball end mill cutter is decided on the interference check between the cutter and body surface of impeller using with the modified z-map method that z-axis is the same of cutter axis direction vector. The exclusive CAM system for an impeller developed in this study was very effective for designs and 50-axis machining of a ruled surface type impeller.

• CDE review
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• v.17 no.3
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• pp.22-25
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• 2011

명확히 말하자면, '모두에 딱 들어맞는 한 사이즈는 없다.' 식의 접근은 이상적인 선반 프로젝트에 이용될 수 있다. 성공적인 프로젝트는 요구된 결과에 큰 수의 요소들을 적절히 균형 맞출 수 있는 능력의 프로그래머를 요구한다. 이 낯선 계산들 때문에, 경험이 있는 프로그래머가 가장 상업적으로 성공한 프로젝트를 운영할 수 있다. 현대 CAM 소프트웨어는 경험이 적은 프로그래머가 베테랑과 경쟁에 설 수 있는 짧은 학습 곡선을 가능하게 한다. 이것은 고려해야 할 요소들의 수를 최소화 시킴으로써 가능하다. 수학적인 계산의 툴 방향을 제공하고, 높은 수준의 프로세스를 시뮬레이션 이전에 보장하고, 회전하는 축에 부가되는 압력을 줄여 주고 자재의 부피를 효율적으로 크게 줄여주는 앞선 생각의 공구경로 알고리즘을 이용함을 통해 성공적인 5축 선반 프로젝트는 보다 편리하게 목표에 도달할 수 있도록 해준다.