• 대한기계학회논문집A
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• 제21권12호
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• pp.2073-2080
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• 1997

Recently, the plane strain puch stretching test(called PSST) has been developed and used successfully in the evaluation of the press formability of automotive steel sheets. In this paper, the optimum punch geometry of the original PSST tool was investigated by the FEM analysis. The puch length, crown and corner radius are chosen to be optimized according to the Taguchi's experiment technique with the $L_4$ orthogonal array.

• 한국정밀공학회지
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• 제13권1호
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• pp.123-130
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• 1996

The procedure on the design of a new tungsten cabide throw-away cutting tool system for deep grooving or cut-off machining is suggested. For relieving the maximum stress level at the corner radius of the blade holder, the finite element method is used. Also the pulling test device is proposed for measuring the holding force of the insert between the blade holder and the insert considering the materials in contact and configuration parameters of the holder.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 추계학술대회논문집
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• pp.158-163
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• 1997

In this paper the tool geometry of the PSS test were optimized in order to assure the reliability of the test. Considering many factors for optimization of the tool geometry, computer-simulation technique using three-dimensional finite element method(FEM) was used. Three design variables -the punch length, punch crown and punch corner radius- are chosen to be optimized according to the Taguchi's experiment technique with the L9 orthogonal array. The optimum condition to ensure the plane strain mode over the overall area of the specimen was clarified. Moreover the simulation results are confirmed by experiment.

• 한국공작기계학회논문집
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• 제13권3호
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• pp.1-7
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• 2004

Abrasive water-jet(AWJ) machining can cut various materials such as metal, glass and plastics. However, the AWJ machining has some troubles including kerf, rounding and side taper. In this study, we experimently investigated the correlation between the traverse speed of the abrasive water-jet and the dimensional error of the workpiece according to the thickness and the types of the material. The specimen was the stainless steel and the mild steel and the predetermined contour cutting was conducted. A comer radius error, an uncut width and a kerf were measured and evaluated.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.837-841
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• 2000

Spinning process is a chipless metal forming method for axi-symmetric parts, which is more economical, efficient and versatile method of producing parts than the other sheet metal forming process such as stamping or deep drawing. It is a point deformation process where a metal disc. cylinderical workpiece. or preform in contact with a rotating chuck is plastically deformed by axial or axial-radial Motions of a tool or roller. in this study the variation of spring back with respect to various forming roller corner radius(Rr) and angle of roller holder($\alpha$) is investigated. Good as a result will help to get more precise shape by control of spring back.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.352-356
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• 1998

This paper is a study about Ac servo motor position and speed control characteristics which depend on feedforward control, the acceleration / deceleration time constant after the interpolation, and PI control, automatic deceleration at corner in order to shape cutting control of feed drive system of the machine tool. The shape error caused by delay of the servo system in the direction of radius at the time of circular cutting is reduced by feedforward control. The shape error generated by the position command delay is minimized by using the acceleration / deceleration time constant after the interpolation. The results were verified to optical machining center experimentation of the machine tool.

• 한국기계가공학회지
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• 제19권3호
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• pp.63-70
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• 2020

Two rotational motions of the 5-axis machine tool maximize the degree of freedom of the tool axis vector, which improves tool accessibility; however, this lowers feed speed and rigidity, which impairs machining stability. In addition, cutting efficiency is lowered when compared with a flat end mill because typically, the ball-end mill is used when machining by rotational motion. This study increased cutting efficiency by using a corner radius flat end mill during impeller roughing. Furthermore, we proposed a fixed controlled machining of the rotary motion using geometric shape information to improve the feed speed and machining stability. Finally, we proposed a finishing tool path generation method using a vector net to increase the convenience and practicality of tool path generation. To verify its effectiveness, we compared the machining time, shape accuracy, and surface quality of the proposed method and an existing dedicated module.

• 한국기계가공학회지
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• 제19권4호
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• pp.71-78
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• 2020

The rotary feed axes of a 5-axis machine tool can increase the freedom of the tool posture, while reducing feed speed and rigidity. In addition, as a ball-end mill is inevitably used during machining by rotational feed, the step-over length is reduced compared to the flat-end mill, thereby reducing the material removal rate. Therefore, this study attempts to improve the material removal rate, feed speed, and machining stability using the corner radius flat-end mill and a fixed controlled machining method for the rotary feed axes during roughing. In addition, the tapered ball-end mill and simultaneously controlled machining method for the rotary feed axes were used for finishing to improve the propeller's 5-axis machining efficiency by enhancing the surface quality. In order to create the tool path effectively and easily, we propose a specific approach for using the propeller's geometric properties and evaluate the effectiveness of the proposed method by comparing it with the method of the dedicated module.

• 한국정밀공학회지
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• 제20권12호
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• pp.168-175
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• 2003

In this paper, the tube forming by radial-forward extrusion is analyzed by numerical simulation and experiments. The paper discusses the effects of process variables such as gap height, relative gap width and die corner radius on tube forming. The influence of deformation patterns of flange in radial extrusion on forward extrusion for tube forming is investigated and summarized in terms of the maximum forming force and hardness variations along the extrusion path. Furthermore the external defects are shown experimentally during the forming operation. Based on finite element analysis in conjunction with experimental test in Al alloy, analysis is performed for important parameter combination in order to reduce forming defects. Eventually, the process parameters for safe forming are suggested in order to reduce the forming defects.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.370-373
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• 2008

It is known that the temperatures of die, punch, holder and punch pad need to be kept different to get better formability in Mg sheet forming processes. Heating and cooling channels are usually equipped in each tool to assign different temperature. This study focused on the optimal design of the heating and cooling channels for a cross-shaped deep drawing die set. While the die and blankholder were heated to and kept at $250^{\circ}C$ by using heat cartridges, the punch and punch pad were kept at much lower temperature than that of the die and blankholder by water circulating through cooling channels. All the approaches were done by numerical analyses, aiming to maximize the cup height and to minimize the punch corner radius without any failure.