研究生: |
Tran Anh Son Tran - Anh Son |
---|---|
論文名稱: |
Automatic Determination of Undercut Regions and Their Releasing Directions
in Plastic Mold Design Automatic Determination of Undercut Regions and Their Releasing Directions in Plastic Mold Design |
指導教授: |
林清安
Alan C. Lin |
口試委員: |
鄭正元
Jeng-Ywan Jeng 周明 Min Jou |
學位類別: |
博士 Doctor |
系所名稱: |
工程學院 - 機械工程系 Department of Mechanical Engineering |
論文出版年: | 2014 |
畢業學年度: | 102 |
語文別: | 英文 |
論文頁數: | 174 |
中文關鍵詞: | CAD 、Injection mold design 、Undercut regions 、Releasing directions. |
外文關鍵詞: | CAD, Injection mold design, Undercut regions, Releasing directions. |
相關次數: | 點閱:322 下載:11 |
分享至: |
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The determination of undercut regions and their releasing directions plays an important role in injection mold design. Most of the approaches in the literature face difficulties in recognizing the undercut regions of real-life parts. This thesis proposes an approach to automating the determination of undercut regions and their releasing directions for complex parts with free-form surfaces. In order to delineate the border of undercut regions, orthogonal cutting planes are firstly employed to automatically find the inner loops of a part model using the concept of “shared vertices” and “adjacent points”. The inner loops are classified into two groups: closed inner loops and open inner loops. In order to determine undercut regions, open loops are further converted to closed ones through the introduction of additional line segments. To discover the surfaces belonging to undercut regions, attributes are then assigned to the surfaces of the part model based on the topological relationship of adjacent surfaces of each inner loop. After that, the concept of “target facets” is proposed to separate the undercut regions from other surfaces in the model. Through the recognized surfaces of the undercut regions, the concept of “visibility map” is further applied to determine feasible releasing directions for each of the undercut regions. Delaunay triangulation is adopted here to represent a set of releasing directions. The undercut regions having the same releasing direction are finally grouped to form a slider in the injection mold.
In addition to proposing the methodologies to find undercut regions and their releasing directions for free-form surfaces, this thesis also uses commercial software packages Pro/Engineer Wildfire 5.0 and Matlab 9.0 to implement the algorithms developed for the proposed methodologies. Several real-life parts, such as cell phone cover and bike helmet, are used as testing examples to demonstrate the applicability of the implemented system. While these example parts contain a large number of complicated free-form surfaces, the implementation results show that undercut regions and their releasing directions can be found within acceptable range of time.
The determination of undercut regions and their releasing directions plays an important role in injection mold design. Most of the approaches in the literature face difficulties in recognizing the undercut regions of real-life parts. This thesis proposes an approach to automating the determination of undercut regions and their releasing directions for complex parts with free-form surfaces. In order to delineate the border of undercut regions, orthogonal cutting planes are firstly employed to automatically find the inner loops of a part model using the concept of “shared vertices” and “adjacent points”. The inner loops are classified into two groups: closed inner loops and open inner loops. In order to determine undercut regions, open loops are further converted to closed ones through the introduction of additional line segments. To discover the surfaces belonging to undercut regions, attributes are then assigned to the surfaces of the part model based on the topological relationship of adjacent surfaces of each inner loop. After that, the concept of “target facets” is proposed to separate the undercut regions from other surfaces in the model. Through the recognized surfaces of the undercut regions, the concept of “visibility map” is further applied to determine feasible releasing directions for each of the undercut regions. Delaunay triangulation is adopted here to represent a set of releasing directions. The undercut regions having the same releasing direction are finally grouped to form a slider in the injection mold.
In addition to proposing the methodologies to find undercut regions and their releasing directions for free-form surfaces, this thesis also uses commercial software packages Pro/Engineer Wildfire 5.0 and Matlab 9.0 to implement the algorithms developed for the proposed methodologies. Several real-life parts, such as cell phone cover and bike helmet, are used as testing examples to demonstrate the applicability of the implemented system. While these example parts contain a large number of complicated free-form surfaces, the implementation results show that undercut regions and their releasing directions can be found within acceptable range of time.
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