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1.
T. Okuno (1), K. Somiya (1), Y. Takagi (1), K. Yano (1), S. Baba (2)
Mie University, Faculty of Eng., Dept. of Mech. Eng., 1577 Kurimamachiya-cho, Tsu, Mie, Japan (1)
Flow Sience Japan, Inc., Tokyo, Japan (2)
OPTIMUM DESIGN OF BRANCH PATTERN CONSIDERING PRODUCT SHAPE FOR DIE CASTING DESIGN
Abstract
Die casting is a method in which molten metal is poured into a sleeve and pressed with a plunger into a precise metal mold at high speed and high pressure. It is used to mass-produce superior casting of cast skin in a short time. Die casting has many advantages, including allowing products with complicated shapes to be molded with dimensional accuracy, and reducing material cost compared to sand mold castings. However, in order to rapidly solidify the molten metal, it is necessary to fill the metal mold quickly and inject the plunger at high speed. Therefore, internal defects such as air entrainment are generated by the blowhole. This is a factor that significantly reduces the mechanical properties of the product. Therefore, measures to address it are needed.
Efforts to prevent such defects from occurring have conventionally used optimally designed gating systems. In this laboratory, in contrast, we propose a nonparametric optimization method using curves. Curves that constitute the outline of the runner shape are used as variables to prevent air entrainment in the gating system. However, as products to be manufactured become larger and more complicated, potential for air entrainment in product also rises. Therefore, it is necessary to consider the product when determining the optimum design of the runner shape. In that case, it may be necessary to change the behaviour of the molten metal in the product substantially. This includes not only the outer shape of the runner, but also the optimum design including branching patterns in design space is necessary.
In this research, we propose a new optimization method including branch patterns in the design space. This method uses both combinatorial optimization and the nonparametric optimization method. For the optimization procedure, we first optimize only the runner shape with all the branching patterns. Next, we optimize the runner shape considering the product as the initial optimum shape obtained as a result. Therefore, this proposed methos is a two-stage optimization.
Finally, we optimally design the runner shape for simple shapes of products manufactured by the die casting method to verify the effectiveness of the proposed methos. We find the method is superior compared to the conventional optimization method.
Key words: HPDC, CFD, Optimum Design, Runner, Branch Pattern
2.
A. Sladek, M. Bruna
KTI, SjF, ŽU Žilina, Univerzitna 1, 010 26 Žilina, Slovakia
NEW APPLICATIONS IN TECHNOLOGICAL PREPARATIONS FOR INVESTMENT CASTING PRODUCTIONS
Abstract
Nowadays, foundries do not sufficiently utilize computer support during the creation of technical documentation. Instead of computer documentation is used classical method for designing technological documentation and the use of computer support is only discrete. For the area of casting technology is not appropriate to use conventional CAPP systems with use of group technology, because they work with a simple representative selection from the database according to the characteristics. The submitted article shows a solution for systems interconnection and the possibilities of using the concurrent engineering. In our department was designed a system serving as the creation tools for technological documentation, whose role is to effectively benefit from group technology.
Key words: Aluminium alloys, reoxidation, gating system, numerical simulation, bifilm
3.
M. Kambič (1), F. Cecchetto (2), P. Grubelnik (1)
Olma d.o.o. (SI) (1), MotulTech-Baraldi (I) (2)
SOME ASPECTS AND CHALLENGES OF LUBRICATING THE FOUNDRY PISTON WITH OIL
Abstract
Lubricating the piston of high-pressure casting machines has always been a unique challenge. A sufficient amount of lubricant has to be added to ensure sufficient lubrication and to achieve an acceptably high number of cycles of the foundry piston and shot chamber. Part of the lubrication burns out during the filling phase of the sleeve, and part of the lubrication passes into melt and thus contaminates it with the combustion products. When lubricant burns, gases and some solid combustion residues occur, which increases the gas porosity od the castings and non-metallic black inclusions.
The part of the lubricant that burns during the filling of the shot sleeve with the melt causes an unwanted flame and the emission of toxic and carcinogenic smoke around a casting machine.
Some synthetic oils offer significantly better lubrication, as the amount of oil needed is significantly reduced.
With better lubricating properties, the number of cycles that can be performed with one piston is increased, and the lifetime of the shot chamber is also extended. By extending the lifetime of the piston and shot chamber and shortening the downtime due to piston replacements, productions costs are also reduced.
Some types of synthetic lubricants are formulated to decompose at high temperatures into non-toxic components that evaporate without residue. The man focus of the article will therefore be on the use of synthetic oils without graphite. With certain synthetic oils, we noticeably reduce the porosity of the castings, eliminate some of the inclusions as residues of lubricant combustion, and significantly reduce the flame. By eliminating the smoke generated by the combustion of classical lubricants, we prevent the emission of toxic and carcinogenic gases thus making the surroundings of the machine safer and cleaner.
Key words: high pressure dies casting, casting machine, piston lubrication, synthetic oil