Heat insulation plunger sleeve for die casting machine

Abstract

The invention provides a plunger sleeve for use in die casting machines which is outstanding in heat insulating and heat-retaining properties and which is capable of suppressing the drop in the temperature of molten nonferrous metal to the greatest extent and maintaining a stabilized casting operation under pressure. The plunger sleeve comprises a first metal layer made of a metal having high heat resistance and forming the inner periphery of the sleeve, a second metal layer providing the outer periphery of the sleeve, and a ceramic layer formed between the first metal layer and the second metal layer. The ceramic layer comprises a ceramic powder and/or a ceramic fiber consolidated to at least 50% to not greater than 90% in relative density.

1 . A heat insulating plunger sleeve for use in die casting machines which comprises a hollow cylinder provided at a base end thereof with a molten metal outlet adapted to communicate with a die and connecting means connectable to the die, the hollow cylinder having an opening at an outer end thereof for a plunger tip to be inserted thereinto and a molten metal inlet formed in a peripheral wall thereof for injecting a molten metal into the cylinder therethrough, 
 the plunger sleeve being characterized in that the sleeve comprises a first metal layer made of a metal having high heat resistance and providing an inner periphery of the sleeve, a second metal layer providing an outer periphery of the sleeve, and a ceramic layer formed between the first metal layer and the second metal layer, the ceramic layer comprising a ceramic powder and/or a ceramic fiber consolidated to at least 50% to not greater than 90% in relative density.    
   
   
       2 . The heat insulating plunger sleeve for use in die casting machines according to  claim 1  wherein the second metal layer comprises a plurality of metal layers, and a ceramic layer comprising a ceramic powder and/or a ceramic fiber consolidated to at least 50% to not greater than 90% in relative density is positioned between the metal layers.  
   
   
       3 . The heat insulating plunger sleeve for use in die casting machines according to  claim 1  wherein each of the ceramic layers is up to 2 mm in thickness.  
   
   
       4 . The heat insulating plunger sleeve for use in die casting machines according to  claim 2  wherein each of the ceramic layers is up to 2 mm in thickness.  
   
   
       5 . The heat insulating plunger sleeve for use in die casting machines according to  claim 1  wherein the first metal layer is 3 to 15 mm in thickness.  
   
   
       6 . The heat insulating plunger sleeve for use in die casting machines according to  claim 2  wherein the first metal layer is 3 to 15 mm in thickness.  
   
   
       7 . The heat insulating plunger sleeve for use in die casting machines according to  claim 1  wherein the first metal layer consists essentially of, in % by weight, 0.32 to 0.42% of C, 0.8 to 1.2% of Si, up to 0.5% of Mn, 4.5 to 5.5% of Cr, 1.0 to 1.6% of Mo, 0.5 to 1.2% of V and the balance substantially Fe.  
   
   
       8 . The heat insulating plunger sleeve for use in die casting machines according to  claim 2  wherein the first metal layer consists essentially of, in % by weight, 0.32 to 0.42% of C, 0.8 to 1.2% of Si, up to 0.5% of Mn, 4.5 to 5.5% of Cr, 1.0 to 1.6% of Mo, 0.5 to 1.2% of V and the balance substantially Fe.  
   
   
       9 . The heat insulating plunger sleeve for use in die casting machines according to  claim 1  wherein each of the ceramic layers comprises at least one powder or fiber selected from the group consisting of Al 2 O 3 , Al 2 O 3 —SiO 2 , ZrO 2 , SiO 2 , Si 3 N 4 , BN, TiB 2 , SiC and MoSi 2 .  
   
   
       10 . The heat insulating plunger sleeve for use in die casting machines according to  claim 2  wherein each of the ceramic layers comprises at least one powder or fiber selected from the group consisting of Al 2 O 3 , Al 2 O 3 —SiO 2 , ZrO 2 , SiO 2 , Si 3 N 4 , BN, TiB 2 , SiC and MoSi 2 .