Masanori Shiomi

Forming of Aluminum Foams by Deposition Process

In order to produce aluminum foams with designed density distribution, a deposition process of aluminum foam is examined. The precursor is made with the mixture of aluminum powder and a blowing agent, and it is heated, extruded with foaming and deposited onto the foam. In the density distribution of an aluminum foam bar made by the deposition process, high density area is found at the connection between the deposited foams. The combination of extrusion with foaming and without foaming makes clear variation of density within the deposited foam.

Influence of Gravity and Mold Shape on Molding of Aluminum Foams

A molding process of aluminum foams by using a rotating mold is proposed in order to improve the mold filling and forming process for light-weight parts of vehicles. Aluminum powder mixed with a foaming agent is extruded into the mold through the die heated to a temperature higher than the melting point, and the mold is filled with the aluminum foam. When the diameter of a cylindrical mold is large, the influence of gravity is significant and the mold is not filled successfully. In the proposed molding, the aluminum foam is extruded into the rotating mold of large diameter and the volumetric ratio of foam to mold cavity is improved. However, the effect of the mold rotation on the mold filling is limited due to friction.

FEM Analysis of Melting Behavior of Metal Powders in Laser Prototyping

F E M Analysis of Melting Behavior of Metal Powders in Laser Prototyping Fumie Abe ,A k i h r o Yoshidome ,Kozo Osakada and Masnori Shiom I n o r d e t o use m e t a l s i n r a p i d p r o t y p i n g ,a f o r m i n g method ,i n whic m e t a l i c powders a r e s u c e s i v e l y m e l t d i n a m i c r o s p i c zone by l a s e r and s o l i d i f i e d ,i s p r o s e d . The c o e f i c i e n t o f t h e h e a t c o n d u c t i v t y o f c o p e r powders was measured and f o u n d t o v a r y t o a l a r g e e x t n by t h e d e n s i t y o f powder. The t e m p r a u change was c a l c u l a t e d by u s i n g t h e f i n i t e e l m n t method. I n t h e a n a l y s i s ,t h e h e a t d p a r t above t h e m e l t i n g p o i n t i s asumed t o m e l t and s h r i n k s t o a b a l l by s u r f a c e t e n s i o n . By comparing t h e c a l c u l a t e d r e s u l t s w i t h t h e e x p r i m e n t a l r e s l t l t s f o r t h e c o m b i n a t o o f coper powders and YAG p u l s e l a s e r ,t h e a b s o r p t i o n r a t i o o f l a s e r beam i s e s t i m a e d t o be a b o u t 0 . 4 The amount o f t h e m e l t d mas a g r e s w e l w i t h t h e e x p r i m e n t a l r e s u l t s f o r v a r i o u s c o n d i t o n s o f l a s e r o p e r a t i o n .