Aluminum alloy casting and method for producing the same, and apparatus for producing slide member

Abstract

There are provided an aluminum alloy casting free from crack-causing needle-shaped crystallized substances and an apparatus and a method for producing a slide member excellent in mechanical properties such as abrasion resistance. A melt of an iron-containing aluminum alloy poured into a vessel in the completely liquid state is vibrated by a vibrating needle of a vibration applying unit, and then a core is inserted into the melt to cool the melt, whereby the aluminum alloy casting is produced as a sleeve of a slide member. The vibrating step is carried out at a frequency of 20 to 1000 Hz, and is continued until just before the melt is cooled to the solid-liquid coexisting temperature region.

1 . An aluminum alloy casting obtained by cooling a melt of an aluminum alloy containing iron, wherein
 a metal structure of at least one surface in the aluminum alloy casting contains the iron in the state of a grain of pure iron or an iron-based intermetallic compound with another metal, and   the metal structure further contains a eutectic silicon having a greatest diameter of 10 μm or less in a two-dimensional surface.   
     
     
         2 . An aluminum alloy casting according to  claim 1 , wherein the aluminum alloy casting is a sleeve having an inner wall and an outer wall, and the inner wall has the one surface. 
     
     
         3 . A method for producing an aluminum alloy casting, comprising the steps of:
 pouring a melt of an aluminum alloy containing iron into a vessel,   vibrating the melt in a completely liquid state using a vibrator at a frequency of 20 to 1000 Hz until the melt is cooled to a solidification point of the melt,   stopping vibrating the melt when the melt is cooled to the solidification point, and   further cooling the melt at a cooling rate higher than that down to the solidification point, thereby solidifying the melt to obtain an aluminum alloy casting, wherein   a metal structure of at least one surface in the aluminum alloy casting contains the iron in the state of a grain of pure iron or an iron-based intermetallic compound with another metal, and   the metal structure further contains a eutectic silicon having a greatest diameter of 10 μm or less in a two-dimensional surface.   
     
     
         4 . A method according to  claim 3 , wherein when the melt is cooled to a solidification starting point, a core having a temperature lower than that of the melt is inserted into the melt, whereby the cooling rate is increased and a cavity corresponding to the shape of the core is formed in the aluminum alloy casting. 
     
     
         5 . A method according to  claim 4 , wherein in the melt, a portion in contact with the core is cooled at a cooling rate of 30° C./second or more, and a portion farthest from the core is cooled at a cooling rate of 10° C./second or less. 
     
     
         6 . A method according to  claim 4 , wherein the aluminum alloy casting is a sleeve having an inner wall and an outer wall, and the inner wall has the one surface. 
     
     
         7 . An apparatus for producing a slide member, comprising
 a vessel for storing a metal melt containing at least a base metal and a hard metal harder than the base metal,   a vibration applying means for vibrating the metal melt in the vessel at a frequency of 1000 Hz or less, and   a core that is inserted into the metal melt vibrated by the vibration applying means to cool the metal melt.   
     
     
         8 . An apparatus according to  claim 7 , wherein the base metal is aluminum, and the hard metal contains iron. 
     
     
         9 . An apparatus according to  claim 7 , wherein the vibration applying means contains a vibration generator and a vibrator,
 the vibration generator has a rotor and an eccentric integrally rotatable with the rotor in an eccentric state with respect to a rotation axis of the rotor, and   the vibrator is connected to the vibration generator, extends in a direction of the rotation axis of the rotor, and is inserted into the metal melt.   
     
     
         10 . An apparatus according to  claim 9 , further comprising
 a stage on which the vessel is placed,   a conveying means for transferring the vessel placed on the stage to a first position and a second position, and   an elevating means for raising and lowering the stage,   wherein   the vibrator is disposed at a position corresponding to the stage in the first position, and   the core is disposed at a position corresponding to the stage in the second position.   
     
     
         11 . An apparatus according to  claim 7 , wherein the vessel comprises a heat insulation material.