Die-casting method and die-casting apparatus

Abstract

A method of die-casting a die-cast article having at least one of an inner circumferential surface and an outer circumferential surface, whose cross sectional shape is a circle, the die-casting article being formed with a die-casting apparatus having a mold cavity therein and a molding portion for forming one of the inner and outer circumferential surfaces of the die-cast article, the method comprising the steps of introducing a molten metal into the mold cavity; and separating the die-cast article and the molding portion from each other while the die-cast article and the molding portion are rotated relative to each other, after the molten metal has solidified into the die-cast article. A die-casting apparatus for practicing the method is also disclosed.

What is claimed is:  
     
         1 . A method of die-casting a die-cast article having at least one of an inner circumferential surface and an outer circumferential surface, whose cross sectional shape is a circle, said die-casting article being formed with a die-casting apparatus having a mold cavity therein and a molding portion for forming one of said inner and outer circumferential surfaces of said die-cast article, the method comprising the steps of: 
 introducing a molten metal into said mold cavity; and    separating said die-cast article and said molding portion from each other while said die-cast article and said molding portion are rotated relative to each other, after said molten metal has solidified into said die-cast article.    
     
     
         2 . A method according to  claim 1 , wherein said die-cast article has a cylindrical hole, said molding portion consisting of a cylindrical portion which forms said cylindrical hole, said cylindrical portion being rotated relative to said die-cast article when said die-cast article and said cylindrical portion are separated from each other.  
     
     
         3 . A method according to  claim 2 , wherein said die-casting apparatus includes: a mold assembly as a main body; and a slide core which has a circular shape in transverse cross section and which is rotatable and axially movable relative to said mold assembly, said slide core being rotated relative to said mold assembly when said slide core is separated from said cylindrical hole of said die-cast article, after said die-cast article has been formed in said mold cavity.  
     
     
         4 . A method according to  claim 1 , wherein said one of said inner and outer circumferential surfaces of said die-cast article includes a plurality of axial portions which have respective different diameters and which are coaxial with one another.  
     
     
         5 . A method according to  claim 1 , wherein said die-cast article is a housing which is used for a compressor and which has a cylindrical hole, said inner circumferential surface of said die-cast article being an inner circumferential surface of said cylindrical hole of said housing.  
     
     
         6 . A method according to  claim 1 , wherein said die-cast article is a cylinder block which is used for a compressor and which has a plurality of cylinder bores, said inner circumferential surface of said die-cast article being an inner circumferential surface of each of said cylinder bores.  
     
     
         7 . A die-casting apparatus for die-casting a die-cast article having at least one of an inner circumferential surface and an outer circumferential surface, whose cross sectional shape is a circle, said apparatus comprising: 
 a first molding member for forming one of said inner and outer circumferential surfaces of said die-cast article;    a second molding member for forming at least one surface of said die-cast article other than said one of said inner and outer circumferential surfaces, said first molding member being rotatable and axially movable relative to said second molding member; and    a drive device for moving said first and second molding members relative to each other in an axial direction thereof while rotating said first and second molding members relative to each other.    
     
     
         8 . An apparatus according to  claim 7 , wherein said drive device includes: a drive source operable to effect one of a relative rotation and a relative axial movement between said first and second molding members; and a motion-generating device operable to effect the other of said relative rotation and said relative axial movement, based on said one of said relative rotation and said relative axial movement.  
     
     
         9 . An apparatus according to  claim 7 , wherein said first molding member consists of a cylindrical portion for forming said inner circumferential surface of said die-cast article.  
     
     
         10 . An apparatus according to  claim 7 , wherein said first molding member includes a slide core for forming said inner circumferential surface of said die-cast article while said second molding member includes a pair of molds which are opened and closed for forming at least one surface of said die-cast article other than said inner circumferential surface.  
     
     
         11 . An apparatus according to  claim 10 , wherein said drive device includes: 
 an axial moving member which is axially movable relative to said pair of molds;    an actuator operable to axially move said axial moving member relative to said pair of molds;    a connecting device disposed between said axial moving member and said slide core and operable to connect said axial moving member and said slide core such that said axial moving member and said slide core are rotatable relative to each other and axially immovable relative to each other; and    a first engaging portion and a second engaging portion which are provided on said pair of molds and said slide core, respectively, said first and second engaging portions being held in engagement with each other and operable to cause said pair of molds and said slide core to be rotated relative to each other on the basis of an axial movement of said pair of molds and said slide core relative to each other.    
     
     
         12 . An apparatus according to  claim 11 , wherein said pair of molds and said slide core have respective two fitting surfaces which engage each other, and wherein said first and second engaging portions have one and the other of an engaging groove and an engaging protrusion fitted in said engaging groove, said engaging groove being formed in one of said two fitting surfaces and having an inclined portion which extends in a direction inclined with respect to an axial direction of said slide core, said engaging protrusion being formed on the other of said two fitting surfaces.