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기하학적인 방법을 이용한 3 Rotary 형식 5축 가공기의 후처리 방법
윤재득(Jaedeuk Yun),정융호(Yoongho Jung),박도현(Dohyun Park) (사)한국CDE학회 2009 한국CDE학회 논문집 Vol.14 No.5
This paper presents a post-processing algorithm for 5-axis machines with three rotary axes (3R-2L type). 5-axis machining needs the postprocessor for converting cutter location (CL) data to machine control (NC) data. The existing methods for post-processing use inverse kinematics equations from forward kinematics. However in case of 5-axis machines with three rotary axes, the inverse kinematics equations are not induced directly since the forward kinematics equations are non-linear. In order to get the joint values from the forward kinematics equations, previous algorithms use numerical method for the post-processing, which needs searching algorithms with computation time and may result in fail. This paper proposes a geometric method for the post-processing of 3 rotary type 5-axis machines. Our algorithm has three advantages: first, it does not need establishing forward kinematics equations. Second, it is reliable method that eliminates any numerical methods for the inverse kinematics, resulting in the exact solution. Finally, the proposed algorithm can also be applied to 2R-3L type of 5-axis machines.
FRP의 원통형 압력 용기제작을 위한 필라멘트 밴드의 감김 시뮬레이션
윤재득(Jaedeuk Yun),Jianhui Fu,정융호(Yoongho Jung) (사)한국CDE학회 2014 한국CDE학회 논문집 Vol.19 No.1
The filament winding method is widely used to manufacture products of fiber reinforced plastics (FRP), such as high pressure vessels, launch tubes and pipes. For reducing winding time, the method of winding by filament band which consists of several filament fibers is used. NC winding machine is used for precise winding and NC path is needed. Before filament winding, users should verify that winding path which presented by a line is appropriate by filament winding simulation. Also, the used length of each filament is different. So, if the peak filament exhausted, it causes to stop manufacturing. In this research, we developed software which visualizes 3D graphic of filament band winding path and simulates winding process on real time. And we proposed algorithm about calculation of each filament usage. We use geodesic equation for generating filament band surface and calculating the usage length of each filament.
주응력의 방향을 이용한 필라멘트 와인딩 복합재의 섬유 궤적 생성
윤재득(Jaedeuk Yun),정융호(Yoongho Jung),푸쟌훼이(Jianhui Fu) (사)한국CDE학회 2014 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2014 No.2
필라멘트 와인딩은 유리나 탄소 섬유를 맨드릴에 감아서 성형하는 공법으로 고압 밀폐 용기나 각종 파이프 등을 제작할 때 사용된다. 필라멘트 와인딩 궤적을 생성할 때는 반드시 구조물에 가해지는 하중의 방향을 고려해서 감겨지는 섬유의 방향을 결정해야 강도 높은 복합재 구조물을 제작 할 수 있다. 본 논문에서는 벡터장에 접하는 곡선을 의미하는 스트림라인을 사용하여 섬유 궤적을 생성하는 방법을 제시하고자 한다. 제안한 방법을 사용하면 구조해석을 통해 생성된 주응력 방향과 정확히 일치하는 섬유의 궤적을 생성할 수가 있다. 또한, 와인딩을 수행할 때 미끄러짐과 같은 현상이 발생하지 않는 섬유 궤적을 생성하는 방법을 제시하였다. 본 연구에서 제안한 방법을 사용하여 동일한 맨드릴 형상에 대해 다양한 하중조건에서 섬유 궤적을 생성하였으며, 그 결과 각각의 하중 조건에 대하여 최적의 섬유 궤적을 생성하였다. 제안한 방법은 삼각면으로 근사화한 모델인 STL 모델을 사용하여 섬유 궤적을 생성하기 때문에 복잡한 형상에도 적용이 가능하다.
윤곽 가공을 위한 삼각 스플라인을 이용한 오프셋 곡선의 생성
고구용(Jiulong Gu),윤재득(Jaedeuk Yun),정융호(Yoongho Jung) (사)한국CDE학회 2010 한국CDE학회 논문집 Vol.15 No.4
This paper presents algorithms for computing offsets of freeform curves. The approach first divides the original curve into several segments at the inflexion points. Based on the obtained new control polygon and its offsets, quadratic trigonometric splines are constructed to approximate the offset curves. Finally, the shape parameter value of trigonometric spline is determined to satisfy the required tolerance. The degree of the output curve is two, independent of the original curve’s degree. Because of the great controllability, the proposed method can generate a completely overestimating offset curve by adjusting the value of the shape parameter, which guarantees no overcutting in NC machining. Furthermore, it also produces the lowest number of control points compared with other works.
소범식(Bumsik So),정융호(Yoongho Jung),윤재득(Jaedeuk Yun) (사)한국CDE학회 2009 한국CDE학회 논문집 Vol.14 No.1
This paper proposes an analytical method of evaluating the maximum error by modeling the exact tool path for the tool traverse singular region in five-axis machining. It is known that the NC data from the inverse kinematics transformation of 5-axis machining can generate singular positions where incoherent movements of the rotary axes can appear. These lead to unexpected errors and abrupt operations, resulting in scoring on the machined surface. To resolve this problem, previous methods have calculated several tool positions during a singular operation, using inverse kinematics equations to predict tool trajectory and approximate the maximum error. This type of numerical approach, configuring the tool trajectory, requires much computation time to obtain a sufficient number of tool positions in a region. We have derived an analytical equation for the tool trajectory in a singular area by modeling the tool operation into a linear and a nonlinear part that is a general form of the tool trajectory in the singular area and that is suitable for all types of five-axis machine tools. In addition, we have evaluated the maximum tool-path error exactly, using our analytical model. Our algorithm can be used to modify NC data, making the operation smoother and bringing any errors to within tolerance.
박재엽(Jaeyeob Bak),김성준(Seongjun Kim),만예동(Ruidong Man),윤재득(Jaedeuk Yun),정융호(Yoongho Jung) (사)한국CDE학회 2020 한국CDE학회 논문집 Vol.25 No.1
Roll-on and roll-off (Ro-Ro) ship is the most economical transporting method for large freights such as train, helicopter, and aircraft body. To ship a large freight to a designated location on deck of Ro-Ro ship, tractor is used to pull a trailer with a connecting link of goose neck shape, on which the freight is secured. When the freight is long enough, the trajectory of trailer is not same as that of trailer and is a three dimensional path, which can cause any collision with ramp, gate, and obstacles in the deck. This research proposes a method of calculating possible trajectories to drive a tractor, along which does not cause any collision. Assuming reasonably low speed of a tractor, the proposed method generates possible tractor paths based on Bezier curve to calculate the trailer path considering tilt of tractor and trailer when they go up the inclined ramp. Finally, it calculates the best three paths without any collision in order of priority with minimum shipping time. The proposed method can be useful for the transport company to determine the shipping possibility as well as to generate driving order for a tractor driver.