Computational fluid-dynamics modeling of the hydrodynamics of fluidization in the sand surrounding a lost-foam casting p
- PDF / 1,772,843 Bytes
- 11 Pages / 612 x 792 pts (letter) Page_size
- 38 Downloads / 157 Views
I. INTRODUCTION
CAST parts are found in most of the durable goods manufactured in the United States. A major problem with their production is the trial and error involved in developing the casting-process designs and methods. Unfortunately for the metal-casting industry, the development of casting manufacturing processes is often part-specific. Indeed, the development of an engineering process that produces a complex cast part is a time-consuming and expensive affair which leaves considerable opportunity for improvement. For example, it can take several years[1] to develop an effective casting process for many complex engine components (blocks, heads, manifolds, etc.), and research continues worldwide into the NATHANAEL HUDSON, formerly a Graduate Research Assistant with the Department of Mechanical Engineering, Auburn University, is now a Department of Energy Fellow with the Neely Nuclear Research Center, Georgia Institute of Technology, Atlanta, GA 30332. SUSHIL H. BHAVNANI and RUEL A. OVERFELT, Professors, are with the Department of Mechanical Engineering, Auburn University, Auburn, AL 36849-5341. Contact e-mail: [email protected] Manuscript submitted June 8, 2001 METALLURGICAL AND MATERIALS TRANSACTIONS B
development of efficient casting procedures on a more scientific basis. This should have the effect of helping manufacturers in the United States become more competitive, while yielding cast parts that are more reliable and less expensive. The lost-foam casting technology is advancing rapidly due to the many inherent advantages that the technology possesses for making complex components. In the typical lost-foam process, a foam pattern is made of expanded polystyrene beads. The pattern is then coated with a fine refractory slurry, and the slurry is allowed to dry. The coated foam pattern is then placed into a metal flask, and molding sand is poured into the flask and vibrated around the pattern to produce the mold. Molten metal is then poured into the foam pattern, which melts and vaporizes, the vapors exiting the pattern cavity through the porous refractory coating. One of the typical problem areas in the lost-foam technique is in getting the loose molding sand to uniformly fill and compact around the foam pattern without distorting the dimensions of the pattern. This problem can become critical if the pattern is for a thin-walled casting with significant complexity. Computational techniques are urgently needed to assist manufacturers in the proper design of the sand-filling process. VOLUME 33B, AUGUST 2002—565
Application of fluidized beds is common and is considered a mature technology employed in many metallurgical processes. Fluidization is an industrial technique whereby a particulate phase (sand, for example) in a vessel is kept in a fluidized state by a steady stream of gas (air), flowing in through the bottom of the bed. Researchers are now considering applying the techniques of sand-air fluidization to lostfoam casting production. The objective involves using the concept of sand particles f
Data Loading...
