茨城大学
理工学研究科(工学野)
機械システム工学領域

顔写真
教授

乾 正知

イヌイ マサトモ
INUI Masatomo
  • 1961年生まれ
  • Tel.0294-38-5204

経歴

  1. 東京大学先端科学技術研究センター助手 1988/04-1991/03
  2. 東京大学工学部講師 1991/04-1993/03
  3. 茨城大学工学部助教授 1993/04-2003/03
  4. 茨城大学工学部教授 2003/04-現在

学歴

  1. 東京大学 工学部 精密機械工学 1984/03 卒業
  2. 東京大学 工学系研究科 情報工学 修士 1986/03 修了
  3. 東京大学 工学系研究科 情報工学 博士 1988/03 中退

学位

  1. 工学博士 東京大学 1991/03

教育・研究活動状況

機械設計製造のコンピュータ支援技術に関する研究と教育
コンピュータグラフィックスなどの幾何情報処理技術を用いて,機械製品の設計や製造を高度化(高品質化,高速化,自動化)するソフトウェア技術の研究・実用化と教育.

研究分野

  1. 生産工学・加工学

研究キーワード

  1. 機械製品の計算機援用設計,計算機援用製造

研究テーマ

  1. 高速かつ頑健な図形処理アルゴリズムに関する研究 離散的な構造を持つ立体データの高速かつ頑健な図形処理アルゴリズムの開発 1997/04-現在
  2. 金型製造の高速化・自動化に関する研究 金型製造において大きな障害になっている工程設計や工具経路計算,工具経路検証を高速に行うアルゴリズムの開発 1997/04-現在

共同・受託研究希望テーマ

  1. 高速かつ頑健な図形処理アルゴリズムの開発 (キーワード) CAD, CAM, コンピュータグラフィックス, GPU 産学連携等、民間を含む他機関等との共同研究を希望 技術相談,受託研究,共同研究 飛び込みでのご相談がそのまま研究につながった例が多数あります.お気軽にメールにてご相談ください.
  2. 金型製造の高度化に関する研究 (キーワード) 金型, CAD, CAM, 工程設計 産学連携等、民間を含む他機関等との共同研究を希望 技術相談,受託研究,共同研究 既に多くのCAD/CAMソフトが出回っていますが,工程設計などの手間のかかる作業を支援できるものは意外に少ないものです.それらの分野をカバーできるプログラムを開発しています.かなり研究志向のテーマですので,大手企業との共同研究を希望しています.
  3. 曖昧さをふくむ形状の計算機処理に関する研究 (キーワード) 公差,形状誤差 産学連携等、民間を含む他機関等との共同研究を希望 共同研究 これは非常に研究志向のテーマです.汎用的な手法は多分ないでしょうから,しばらくは個々のケースについて最適な手法を検討していくことになるでしょう.

著書

  1. GPU並列図形処理入門 乾 正知 技術評論社 2014/03/25 978-4-7741-6304-8 GPUの並列処理機能を活用して様々な図形処理を高速に行う手法を,OpenGLとCUDAのサンプルプログラムを交えて解説した.
  2. CIMの設計と構築 (共著) 佐田登志夫,他多数 オーム社 1992 4-274-03383-X
  3. Artificial Intelligence in Design (共著) D.T.Pham 他多数. Springer-Verlag 1991 3-540-50634-9

論文

  1. 研究論文(学術雑誌) 共著 Bounded distance field for assisting interactive layout design of water circuits Masatomo INUI, Tomohiro IMAI and Nobuyuki UMEZU Journal of Advanced Mechanical Design, Systems, and Manufacturing 13/ 4 2019/05 The idea of a “bounded distance field” is proposed, which is a distance field in a limited region around the boundary surface of a solid object. Gaps generated during parts placement that are too narrow can be detected by checking the distance value at the surface polygon of the object in the field. Based on a placement of new objects or a position change of objects, the distance field in the modeling space must be updated. To reduce the update cost, we introduce the idea of a “lazy evaluation” into the distance computation. In this method, a thickness and clearance evaluation is performed by using individual fields associated with the objects, and the computation of the combined distance field of all objects is postponed for as long as possible. To evaluate the practical application of the bounded distance field and the lazy evaluation of the distance value, an interactive system to assist in the layout design of water circuits in a mold cavity is demonstrated.
  2. (MISC)総説・解説(商業誌) 単著 CAM/加工シミュレーションを活用したモノづくり技術の今後の展開 乾正知 機械技術, 2019年1月号 日刊工業新聞社 16-21 2019/01
  3. 研究論文(学術雑誌) 共著 Cutter Engagement Feature Extraction Using Triple-Dexel Representation Workpiece Model and GPU Parallel Processing Function M.Inui, M. Kobayashi, N.Umezu Computer-Aided Design and Applications 16/ 1, 89-102 2019/01 10.14733/cadaps.2019.89-102 For an accurate analysis of the cutting force, the cutter engagement feature (CEF) representing the contact area between the cutter and workpiece must be extracted for each small feed motion of the cutter. We previously proposed a method for accelerating the CEF computation using the parallel processing function of a graphics processing unit. To improve the stability in the CEF computation, we propose a novel CEF extraction algorithm using an intersection analysis between the cutter and the workpiece shape. A triple-dexel model is adopted to represent the workpiece shape to realize a highly accurate computation. The algorithm is extended to compute the CEF, not only for the cylindrical surface portion of a cutter but also for the flat area of a flat-end cutter and the spherical surface area of a ball-end cutter. Our cutting simulation system based on this algorithm can compute a single CEF in 0.12 ms to 0.25 ms.
  4. (MISC)研究論文 共著 GPUによる工具工作物接触面積検出の高速化 乾正知, 小林正佳 型技術誌, 2018年12月号 日刊工業新聞社 62-63 2018/12
  5. 研究論文(学術雑誌) 共著 Visualization of potential sink marks using thickness analysis of finely tessellated solid model Masatomo Inui, Shunsuke Onishi, Nobuyuki Umezu Journal of Computational Design and Engineering 5/ 4, 409-418 2018/10 https://doi.org/10.1016/j.jcde.2018.02.003 Sink marks are unwanted shallow depressions on the molded plastic surface caused by localized shrinkage during the hardening process of injection molding. Sink marks appearing in the exterior impair the aesthetic quality of the product. In this study, a novel method for extracting potential sink marks that can occur on the part surface is proposed. The thicker portion of the part shrinks with a greater amount than that of the thinner portion. This difference in the shrinkage amount is the main cause of the sink mark. In the plastic part design practice, engineers often check the thickness distribution to predict potential sink marks in the part surface. Our method can be considered as an automated technique of such manual inspection task. A polyhedral solid model of the part with sufficiently small triangles of nearly the same size is prepared. The amount of shrinkage at each polygon is estimated based on its thickness and the shrinkage ratio of the part. The developed algorithm extracts the potential sink marks by analyzing the shrinkage distribution on the part surface.

研究発表

  1. 口頭発表(一般) Milling simulation-based approach for determining optimal milling direction of ejector pin International Congress and Conferences on Computational Design and Engineering 2019 (I3CDE 2019) 2019/07 In the injection molding, ejector pin is used to push out the molded product from the mold core. Since the top surface of the ejector pin is a part of the mold surface, it must be machined to have the same curved shape of the mold surface. Fixed 5-axis milling method is usually used for fabricating the ejector pin. Determination of a proper milling direction of the ejector pin is important in the fixed 5-axis milling. In this paper, the authors propose an algorithm for automatically determining the optimal milling direction of the top part of the ejector pin. Our algorithm extracts the top part of the pin-shape as a target shape of the machining. Some candidate cutter axis directions are selected based on the geometric property of extracted target shape. For each candidate direction, a CAM software is applied to generate a cutter path for machining the target. Cutting simulation system is further applied to obtain the result shape of the machining. The optimal milling direction is determined as a direction whose corresponding milling result has the maximum machined area in the target shape.
  2. 口頭発表(一般) Contour-Type Cutter Path Computation Using Ultra High Resolution Dexel Model Proceedings of CAD’19 2019/06 We propose a novel algorithm for computing a contour-type cutter path for a mold CAD model in the polyhedral representation. Our algorithm uses a Minkowski sum shape of the mold model and a cutter model in the inverted orientation. To realize robust Minkowski sum computation, a grid-based shape representation named two-directional dexel model is used. This method can represent the 2D object with much smaller amount of the memory than the regular square mesh-based method. Utilizing this advantage, we realize two-directional dexel models based on an ultra-high-resolution grid. Parallel processing with many cores of graphics processing unit (GPU) is also introduced for reducing the computation time. An experimental path computation software is implemented and its accurate and robust performance is demonstrated.
  3. 口頭発表(一般) Towards Construction of Innovative Digital Validation Environment 77th ISO TC184/SC4&WGs Toulouse Meeting OTF (Open Technical Forum) 2019/05 Innovative digital validation technology is a technology for supporting early phase functional design of mechano-electric/electrical and software product where 1D CAE serves as a key technology. The following three interface functions are key requirements for realizing innovative digital validation technology. Interface for realizing co-simulation of multiple simulations in different technical domains (mechanical, electrical, electric and software domains). Interface for sharing 1D CAE model and model-related documents between different companies in the collaborative design. Interface for connecting 1D CAE models and 3D CAD models so that the simulation result is properly reflected to the shape models of 3D CAD and CAE and vice versa. We plan to refine the requirements on the interface mechanism and specify available information technology for realizing the mechanism. They will be included in the technical report we intend to develop.
  4. 口頭発表(一般) GEOMETRIC APPROACH FOR EVALUATING MANUFACTURABILITY OF PARTS PRODUCED WITH INJECTION MOLDING AND DIE CASTING Proc. of Model Based Enterprise Summit, 2019 2019/04 Cost and time reduction of mold and die production is a critical issue for any manufacturing company. Machine part designers are not always manufacturing experts; therefore, they often design parts with various problems for manufacturing using injection molding and die casting. These problems are usually detected by manufacturing engineers in later production stages. Problems are reported to the part designer, and they are resolved by modifying the part shape. The reduction of such reworks would aid the efficient production of the mold and die and, consequently, efficient part production. In this work, a software system, named “manufacturability assistant”, that reduces the number of reworks is explained. This system detects the shape elements of a part with potential manufacturability problems by applying various shape extraction procedures to the computer-aided design model of the part. By using this system, designers can evaluate the quality of a part from the perspective of manufacturability. They can reflect the evaluation result in the part design to obtain a part with higher manufacturability
  5. ポスター発表 Study on Efficient Development of 1D CAE Models of Mechano-Electrical Products 13th International Modelica Conference 2019/03 To promote the use of 1D CAE model in the mechano-electrical industry, it is necessary to resolve the issues associated with the model and reduce the cost of creating it. We are in the process of developing the guidelines for creating proper 1D CAE models that will help reduce the modeling cost. A mechano-electrical product is generally a complex system of mechanical, electrical/controlling, and software components. In the industry, Modelica and MATLAB/Simulink are emerging as popular tools for modeling the mechanical and electrical/controlling components, respectively. Programming languages derived from C are usually used for describing the software necessary in the mechano-electrical product. For example, SystemC is recognized as a standard tool for describing a hardware behavior in the design of electronic circuits to be incorporated in the product. In this study, we investigated a method for the combined use of these tools. We explain our findings in our experimental construction of 1D CAE models of a mechano-electrical product using Modelica, MATLAB/Simulink, and SystemC simultaneously.

知的財産権

  1. 特許 機械加工検証支援方法および装置,機械加工検証支援用プログラムおよび記憶媒体 2008-139125 2008
  2. 特許 機械加工検証支援方法および装置,機械加工検証支援用プログラムおよび記憶媒体 特願2007-291807 2007/11/09
  3. 特許 工具の加工姿勢設定法 特願2005-369151 2005
  4. 特許 加工経路の生成方法,加工残りの判定方法,加工経路の生成用プログラム,加工残り判定用プログラムおよび記録媒体 特願2004-103141 2004
  5. 特許 工具経路面計算方法,工具経路面計算プログラム,及び工具経路面計算プログラムを記録した記録媒体 特願2002-056858 2002/03/04 特許第3792584号 2006/04/14

受賞

  1. Best Paper Award 2019 Integrated Congress and Conferences on Computational Design and Engineering
  2. 精密工学会論文賞 2018 実験とシミュレーションによる砥粒径のばらつきがウエハ研削面に与える影響の調査
  3. Best Paper Award, The 15th International Conference on Precision Engineering Data Conversion from Dexel Model to B-reps Solid Model 2014/07/24
  4. 奨励賞 コンピュータグラフィックス技術を利用したCAM処理の高速化(型技術者会議2004) 2005/06/15
  5. Best Paper Award, 2003 IEEE International Symposium on Assembly and Task Planning Inverse Offset of Z-map Model for Process Planning Assistance 2003/07/10

担当授業科目

  1. 幾何情報処理
  2. 幾何情報処理(Bコース)
  3. 機械製造技術特論
  4. 応用情報システム(Bコース)
  5. コンピュータシステムⅡ

所属学協会

  1. 精密工学会 1984/04-現在
  2. 情報処理学会 1984/04-現在
  3. 電気電子学会(IEEE) 1984/04-現在
  4. 計算機学会(ACM) 1984/04-現在

委員歴

  1. 精密工学会 理事 2010/04-2012/03