SUMMARY OF PHD. THESIS

Transcription

1 FACULTY OF MACHINE BUILDING Eng. Sever-Adrian Radu SUMMARY OF PHD. THESIS Theoretical and experimental researches regarding the vacuum casting of the non-metallic complex parts PhD. Supervisor Prof. Dr. Ing. Petru Berce Cluj-Napoca 2011

2 FACULTY OF MACHINE BUILDING Eng. Sever-Adrian Radu SUMMARY OF PHD THESIS THEORETICAL AND EXPERIMENTAL RESEARCHES REGARDING THE VACUUM CASTING OF THE NON-METALLIC COMPLEX PARTS PhD. Supervisor, Prof.dr.eng.Petru Berce Committee for public upholding: PRESIDENT: MEMBERS: - Prof.Dr.Eng. Dănuţ JULEAN Vice Dean, Faculty of Machine Building, Technical University of Cluj-Napoca; - Prof.Dr.Eng. Petru BERCE PhD Supervisor, Faculty of Machine Building, Technical University of Cluj-Napoca; - Prof.Dr.Eng. Nicolae-Valentin IVAN - Reviewer, Transilvania University of Braşov; - Prof.Dr. Eng. Laurenţiu SLĂTINEANU - Reviewer, Gh. Asachi University of Iaşi; - Prof.Dr.Eng. Nicolae BÂLC Reviewer, Faculty of Machine Building, Technical University of Cluj-Napoca. Cluj-Napoca 2011

3 Contents Introduction Chapter 1. Technologies posibility of manufacturing the active elements of molds Introduction Cutting manufacturing of molds active elements [3],[4] Molds manufacturing by CNC systems Cold compressing manufacturing of mold cavities [8], Deep-drawing dies for car body panel [9] Dies for deep-drawing combined with blanking operations Electric erosion processing of the mold components Processing by solid electrode [3] Processing by wire cutting Molds processing by Metal Spraying technology [19] Manufacturing of silicone rubber molds [19] Comparative studies. Conclusions Chapter 2. Objectives of the PhD. thesis Chapter 3. Evolution of Rapid Prototyping systems and manufacturing Introduction Actual systems of Rapid Prototyping manufacturing Sistemized technologies of FRP Stereolitography (SLA) Laminated Objet Manufacturing (LOM) Fused Deposition Modelling (FDM) Solid Ground Curing (SGC) D Printing Selective Laser Sintering (SLS) Selective Laser Melting (SLM) Chapter 4. Application of RSM to optimize the vacuum casting process Introduction Development of the mathematical model... 80

4 4.2.1 Liniar regression model Evaluation of the parameters included in a liniar regression model Assessing the adequacy of the model ANOVA dispersion analysis Principle of the dispersion analysis Data structure Interpretation of the bifactorial ANOVA results Conclusions Chapter 5.Numerical simulation of vacuum casting non-metallic parts General aspects Steps of the numerical simulation of vacuum casting process Experimental determination of poliurethanic resin viscozity Chapter 6.Modeling and optimization of vacuum casting process in the silicone rubber mold Introducere Standard optimization using the numerical analysis Optimization using the numerical analysis and response surface methodology Stages of the mathematical model development Planning the experiment Mathematic model of filling the mold time Mathematic model of air bubbles volume from casting parts Mathematic model of the viscozity resin Conclusions Chapter 7. Experimental researches regarding the vacuum casting of the non-metallic parts int to the silicone rubber molds General aspects Elastomers clasification Manufacturing master model using Selective Laser Sintering technolgy Steps of manufacturing the silicone rubber mold to obtain the vacuum casting the non-metallic parts Analyzing of the master model

5 7.4.2 Cleaning and protection of the master model surfaces Materialization of the parting line Box construction, suspending the master model, attaching the feeder and risers The first degasification of the silicone rubber The casting of the silicone rubber mold in the box and the second degasification The separation of the upper mold and removing the master model Preparation of the silicone rubber mold casting Vacuum casting of resins Vacuum casting of SG95 polyurethanic resin Vacuum casting of F19 polyurethanic resin Vacuum casting of Enydyne polyester resin Vacuum casting of Larit L285 epoxy resin Vacuum casting of wax parts Experimental determination of the air bubbles captured in the cast parts Chapter 8. Synthesis of the experimental research on the vacuum casting of non-metallic parts Variation of the filling time Volume of the air bubbles captured in the cast parts Viscozity of the resin cast under vacuum conditions Dimensional accuracy of the cast parts Measurement of the resin parts Measurement of the wax parts Chapter 9. Final conclusions, personal contributions and future perspectives of the research Theoretical contributions Applicative contributions Future perspectives of the researches Bibliography Appendices

6 Appendix 1 Measurement protocol of the casting parts dimensions and for the resin and wax too; Appendix 2 Source code of Visual C++ programm which defines the minimum and the maximum of the STL file, to arrange the funnel and the risers adequately; Appendix 3 - Source code of Visual C++ programm to optimize the quantity of the silicone rubber according the dimensions of the master model and calculate the exact quantity of the resin automaticaly; Appendix 4 Determination of the filling time of a silicone rubber mold ussing the simulation software MoldFlow according to the experiment design Abstract of the PhD. Thesis Keywords: silicone rubber molds, vacuum casting, rapid tooling, rapid prototyping, injection molding resins, MoldFlow simulation, response surface methodology. Rapid Prototyping (RP), a new forming process and principle, is an important breakthrough in the manufacturing industry. It was developed in the late 1970s and 1980s. RP technology allows the production not only of models and prototypes for visualization purposes, but also of functional parts. Industrial competition has accelerated the development of Rapid Prototyping systems. The use of rapid prototyping systems can accelerate manufacturing process and the marketplacement of products. Consequently, reducing the processing time and ensuring the precision of the production have dominated the improvement of rapid prototyping systems. The PhD thesis entitled Theoretical and experimental researches regarding the vacuum casting of the non-metallic complex parts is structured in 9 chapters and 4 appendices, their content being briefly presented as follows. Chapter 1, entiled Technological possibilities of manufacturing the active elements of moulds presents the significant technologies of obtaining the active elements of the molds and comparisons between these technologies, emphasizing a few criteria such as:

7 the dimensional accuracy, the roughness, the class of fabricated products, the productivity of the manufacturing, the construction time and the cost of these technologies. Chapter 2 of the PhD thesis summarize The objectives of the PhD thesis. The principal objectives of this PhD thesis are: - A study on the research in the field of vacuum casting using silicone rubber molds at national and international level; - Research on the optimisation of the vacuum casting process(filling time, temperature of the cast material and corect placement of the funnel and especially of the risers) to obtain quality products taking into account both the economical and functional aspects; - Using the RSM method for obtaining nonmetallic parts by vacuum casting in the silicone rubber molds and identifying the mathematical model used for establishing an accurate connection between the variables of the casting process; - Using the Visual Basic programming language to optimize the dimensions of the silicone rubber mold box by considering the master model in use; - Testing four resins to obtain a minimum volume of air bubbles in the parts; - Experimental determination of the viscozity of SG95 poliurethanic resin considering the mixing time and the temperature of the resin; Chapter 3, entiled Evolution of Rapid Prototyping systems and manufacturing presents Rapid Prototyping classification systems, a brief description of the manufacturing technologies by material deposition or removal. For each of this RP systems the materials used to obtain a few parts are presented, focusing on the advantages and disadvantage of the technologies. Chapter 4, entiled Aplications of RSM to optimize the vacuum casting process present the mathematical formulation of this method, which is a collection of statistical and mathematical techniques used for developing, improving and optimizing processes. The mathematical regression models are presented and the methodology of verifying the accuracy of the model on its ability to describe the relationship response and independent variables. Chapter 5 present Numerical simulation of vacuum casting nonmetallic parts using Autodesk MoldFlow programme and determination of poliurethanic SG 95 resin viscozity by experiments.

8 Chapter 6, entitled Modeling and optimization of vacuum casting process in the silicone rubber mold describes the methodology of the three mathematical models obtained. The first model describes the connection between the mold filling time, the temperature used for melting the wax and the temperature used for heating the mold. The second mathematical model describes the connection between the number of risers, the mold temperature and the bubbles volume which has been entrapped in the parts. The last mathematical model describes the connection between the viscozity of the resin and the mixing time of the mixture. Chapter 7, entitled Experimental researches regarding the vacuum casting of the nonmetallic parts in silicone rubber molds describes the materials wich are going to be vacuum casted in the silicone rubber mold (especially the f types of resin and three types of wax). It is also presented the way which the model master is realized by Selective Laser Sintering. This chapter presents the steps of obtaining the silicone rubber molds by two methods. In the end of the chapter the experimental determination of the air bubble volume obtained by vacuum casting parts is presented. Chapter 8, The synthesis of th results about vacuum casting of nematallic parts presents the analysis of the results considering swiching the filling time, volume of the bubbles captured in the parts, the viscozity of the resin and finally the accuracy of casted parts. The last chapter of the PhD thesis, Chapter 9, entiled Final conclusions, personal contributions and future perspective of the researches emphasisez the main original contributions of the author and presents possible future directions of the theoretical and experimental researches that could be developed in this field. Cluj-Napoca, Eng. Sever-Adrian RADU Theaching Assistant