Application of Integrated Database to the Casting Design

Transcription

1 J. Mater. Sci. Technol., Vol.24 No.3, Application of Integrated Database to the Casting Design In-Sung Cho, Seung-Mok Yoo, Chae-Ho Lim and Jeong-Kil Choi KITECH, 7-47 Songdo-dong, Yeonsu-gu, Incheon, , KOREA [Manuscript received September 22, 2007] Construction of integrated database including casting shapes with their casting design, technical knowledge, and thermophysical properties of the casting alloys were introduced in the present study. Recognition technique for casting design by industrial computer tomography was used for the construction of shape database. Technical knowledge of the casting processes such as ferrous and non-ferrous alloys and their manufacturing process of the castings were accumulated and the search engine for the knowledge was developed. Database of thermophysical properties of the casting alloys were obtained via the experimental study, and the properties were used for the in-house computer simulation of casting process. The databases were linked with intelligent casting expert system developed in center for e-design, KITECH. It is expected that the databases can help non casting experts to devise the casting and its process. Various examples of the application by using the databases were shown in the present study. KEY WORDS: Integrated database; Casting design; Shape recognition 1. Introduction Casting processes, which has a long history from the bronze-age of several thousand years ago, have continued to manufacture the metal products in a convenient way and the numbers of the casting processes and their technologies have been developed. However the making of castings is known as very difficult task, since there are no same casting design for producing the various products, so that the casting engineer must have a new design when the new casting is needed to be produced. The only way to overcome the difficulty is found to be experiences of the casting experts, who have worked for a long time in this field. Nowadays Korean foundries face serious problems such as aged casting engineer experts and longer delivery date for lack of ability of process design. The problems may discontinue casting expert experiences; therefore the foundries may lose international competitiveness in world markets without knowledge and power for the fast and systematic casting product/process design. In order to solve the problem, a new paradigm is necessary. This article discusses a new paradigm for the preserving the knowledge of the casting technology, such as construction of the integrated database for designing casting systems and process parameters. This article also discussed its application to the real casting processes. 2. Construction of Integrated Database and Its Applications Figure 1 shows a flow and relation diagram of intelligence expert system with integrated database. The intelligent expert system had been developed since 2001, sponsored by MOCIE (Ministry of Commerce, Industry and Energy, Korea). The intelligent expert system consists of computer simulation of the casting processes, the intelligent casting design system and the optimization of the casting design, Ph.D., to whom correspondence should be addressed, ischo@kitech.re.kr. and integrated database for their support. The three parts aforementioned were linked with each other, in order to help novice casting expert. The integrated database consists of casting shape database, technical knowledge database, and thermo-physical properties for the casting simulation. Three kinds of database will be discussed in detail thereafter. 2.1 Construction of casting shape database and its application The shape database has 3D casting shapes in CAD format and their casting design data in geometric parameters. Figure 2 shows a schematic diagram of the workflow of automatic casting design. Initial casting design can be retrieved from the shape database, if one want to make a new casting design. The initial casting design is then simulated and optimized by computer simulation, and the design is stored back to the shape database and used for the future casting design [1 8]. Figure 3 shows a schematic diagram for shape recognition system. As shown in Fig.3(a), the 3D casting shape can be stored as shape at 6-axis and 2D sectional data and the shape retrieval system. The stored data then extracted unique features from the 2D images, and the features are vectorized. These vectors of the recognition system can be used by measuring similarities. For the present study, Fourier descriptor, immortal moment descriptor, edge histogram descriptor, multi-eigenvector, curvature scale space descriptor, robust pattern recognition descriptor of the descriptors in MPEG-7, were used for the shape descriptors. Figure 3(b) shows a retrieval system program. If someone needs to retrieve an adequate casting design from the shape database, one will use the casting retrieval system, and after retrieval of the similar casting shape, the casting design also can be obtained. At that time the shape database must have a casting design database, and offer the casting design CAD file. Figure 4 shows construction of shape database by industrial computer tomography (CT). The castings and casting designs were reversely engineered by industrial CT converted to CAD file.

2 352 J. Mater. Sci. Technol., Vol.24 No.3, 2008 In addition, the shape database also needs CAD Fig.1 Flow diagram and the relation of intelligent expert system with integrated database Fig.2 Schematic diagram of the workflow of automatic casting design with integrated database Fig.3 (a) Schematic diagram of the construction of shape database and (b) casting shape retrieval system design files for each casting shapes, in order to incorporate with automated casting design system. The parameter based geometry files were used in the present study, as shown in Fig.5. Figure 5(a) shows CAD file of casting with casting design. The casting design was cut out, and replaced by simple geometry with parameters, as shown in Fig.5(b). The parameters can be written as Fig.5(c). The geometry of casting design such as riser, sprue, runner and ingate was then aromatized by using the modeler, and applied to automated design of the casting. In order to design the gating and riser system automatically, a parametized geometric modeler must be provided. The parametric modeler for casting design was developed with commercial CAD software such as Unigraphics NX, etc. Figure 6 shows

3 J. Mater. Sci. Technol., Vol.24 No.3, 2008 a workspace of the modeler of the expert system[8 9]. 353 The document database mainly contains documents published in KITECH such as casting technol- 2.2 Construction of technical knowledge database and its application Fig.4 Process for obtaining casting shapes (a) CT Scanning, (b) Reverse engineering, (c) Cut out casting design and arrangement Fig.5 Example for shape database (a) scanned casting geometry, (b) processed geometry with parameter, (c) parameters for casting design defects for ferrous alloys. Since the documents were mostly the printed matters, the documents were converted to electronic documents and arranged by the keyword[10]. The pages of documents collected reaches over pages. Also the database covers articles of Journal of Korean Foundrymen s Society from the first volume to volumes in Center for e-design, KITECH, has endeavored to collect technical documents continuously, the database is updating regularly. Fig.6 Workspace of the modeler with Unigraphics NX CAD Software ogy handbook, newsletters, and seminar data books, and trouble shooting data which present solutions for die-casting defects for non-ferrous alloys and casting The search engine for the document was also developed featuring keyword search and full-text search, as common internet search engines have. The search engine can apply to on-line (via internet), with the help of Microsofts NET technology. The search engine was programmed with Visual C#. Figure 7 shows a schematic diagram of the search engine for document database.

4 354 J. Mater. Sci. Technol., Vol.24 No.3, 2008 The search engine, named DBManager, has a function of searching the documents from database incorporated with SQL server, and display data. Also it equips with interaction with intelligent casting design module (Z-Design, ForCasts), and simulation program (Z-Cast). Interactions can be accomplished by using windows messaging feature. For the interaction with Z-Cast, the message hooking scheme was used. When the user positioned the Fig.7 Schematic diagram of the search engine for document database by using the word. After searching the word, DBManager displays the title and abstract of the searching results, and displays the detailed contents by clicking the title. Figure 8 shows the menus of DBManager. Figure 8(a) shows a DBManager displaying titles searched, and Fig. 8(b) shows DBManager displaying contents searched by keyword. DBManager communicates with Z-Design with windows messaging technology. Z-Design have a help (? mark button) in the menus. When user click the? mark button, pre-determined keyword automatically goes to DBManager, and DBManager searches the keyword sent, and displays the appropriate contents. Fig.8 Menu and display of DB Manager, technical knowledge database search engine mouse over the Z-Cast program, DBManager recognizes the word over it, which automatically searches 2.3 Construction of Thermo-physical Properties Database The physical property database contains the physical properties of 76 ferrous and non-ferrous alloys such as Al, Cu, Mg alloys. The properties were obtained by thermal analysis experiment in 9 Korean academies and a research institute, establishing thermo-physical properties database. The properties list density, heat capacity, thermal conductivity, liquidus and solidus temperature, latent heat and viscosity. Moreover, mechanical properties such as Young s modulus, Poisson s ratio were obtained for selected materials, and TTT diagram for various steels were obtained for the simulation of heat treatment process. Thermo-physical properties data are linked with

5 J. Mater. Sci. Technol., Vol.24 No.3, simulation module for simulation input data, and improve precision of simulation result. 3. Concluding Remarks In the present study, the construction of the integrated database for the designing of casting and the casting processes was discussed. The integrated database could be used for the automated casting design, retrieving the most similar shape of the casting from the shape database, and applied for the newly introduced casting. The technical knowledge database can help non-experts to design the casting and casting processes quickly and easily. Finally, the thermo-physical database was used for the accurate simulation for the casting processes. The integrated database is expected to be a new paradigm that the foundries have international competitiveness in world markets with the knowledge and power for the fast and systematic casting products and processes. REFERENCES [1 ] Korean Patent No [2 ] Korean Patent No [3 ] Korean Patent No [4 ] Korean Patent No [5 ] Japanese Patent No [6 ] EU Patent No. ep [7 ] US Patent No [8 ] I.S.Cho, S.M.Yoom, C.H.Lim and J.K.Choi : Proc. of the 1st Korea-Sino Advanced Computer Modeling Conference for Manufacturing Technoliogies, 2006, 115. [9 ] C.H.Lim, J.H.Nam, I.S.Cho, S.M.Yoom and J.K.Choi: Proc. World Foundry Congress 67, 2006, 173. [10] I.S.Cho, S.M.Yoo, Y.S.Choi, J.K.Choi, M.K.Choi and J.I.Kim: Prof. of Korean Foundrymens Meeting, 2006, 130.