Insertable riser base, sand mould, moulding device consisting of the insertable riser base and the sand mould, and method for producing the moulding device

Abstract

The riser base is an insert obtained by manual moulding or by blowing having an insulating or exothermal composition. The composition includes hollow microspheres of aluminium silicate. The mould is mainly comprised of silica sand and presents a main cavity configured to be filled with molten metal to obtain a cast part and one or several auxiliary cavities. The insert fits into the auxiliary cavity made in the mould and presents an interior cavity configured to receive molten metal from a feeding riser or mini-feeding riser and an exterior geometry which coincides with the geometry of the aforesaid auxiliary cavity. The auxiliary cavity or cavities made in the mould itself are disposed in such a way that when the riser base is inserted into the auxiliary cavity, the interior cavity of the riser base is left in communication with the main cavity of the mould to allow passage of the molten metal.

1 . A riser base insertable into a sand mould for casting metal parts, which comprises a main cavity configured to be filled with molten metal to obtain a cast part and at least one auxiliary cavity, wherein the riser base has an exterior geometry that allows the insertion of the riser base into the at least one auxiliary cavity of the mould, and in that the riser base further includes an interior cavity which communicates said main cavity of the mould with a feeding riser, when the riser base is inserted into the at least one auxiliary cavity, said riser base comprising an insulating or exothermal composition. 
     
     
         2 . The riser base according to  claim 1 , wherein the insulating or exothermal composition comprises hollow microspheres of aluminium silicate and a binder, the hollow microspheres presenting an alumina content of equal to or less than 38% in weight. 
     
     
         3 . The riser base according to  claim 2 , wherein the hollow microspheres present an alumina content of 20 to 38% in weight. 
     
     
         4 . The riser base according to  claim 2 , wherein the insulating or exothermal composition comprises non-fibrous fillers, selected from the group formed by oxidable metals, oxidants, and inorganic fluorinated fluxes. 
     
     
         5 . The riser base, according to  claim 2 , wherein the insulating and/or exothermal composition comprises cold or hot box curing binders. 
     
     
         6 . The riser base according to  claim 1 , wherein the exterior geometry is prismatic, truncated pyramidal, cylindrical, or semi-spherical. 
     
     
         7 . A sand mould for casting metal parts, configured to receive the incorporation of an insertable riser base provided with an interior cavity configured to receive molten metal from a feeding riser, wherein the sand mould comprises a main cavity which can be filled with molten metal to obtain a cast part and, at least, one auxiliary cavity with a geometry that allows the insertion of said riser base, the auxiliary cavity being disposed in respect to the main cavity in such a way that, when the riser base is inserted into the auxiliary cavity, the interior cavity of the riser base puts said main cavity of the mould in communication with a feeding riser, and in that the sand mould is made of silica sand. 
     
     
         8 . The sand mould according to  claim 7 , wherein the interior geometry of the auxiliary cavity is prismatic, truncated pyramidal, cylindrical, or semi-spherical. 
     
     
         9 . A moulding device formed by the sand mould according to  claim 7 , wherein said riser base is inserted into said sand mould. 
     
     
         10 . A method for obtaining a moulding device for casting cast parts wherein the method includes the following steps:
 Obtaining a mould of silica sand which comprises a main cavity which can be filled with molten metal to obtain a cast part and at least one auxiliary cavity which presents a geometry that is configured to allow the insertion of a riser base;   Obtaining the riser base having a composition of insulating and/or exothermal material, which comprises an interior cavity to receive molten metal from a feeding riser and an exterior geometry that allows the insertion of the riser base into the at least one auxiliary cavity of the mould.   Inserting the riser base in the at least one auxiliary cavity of the mould, in such a way that the interior cavity of the riser base is in communication with the main cavity of the mould.   Placing a feeding riser on the riser base, in such a way that the interior of the riser is in communication with the interior cavity of the riser base.   
     
     
         11 . The method according to  claim 10 , wherein the riser base comprises an insulating or exothermal composition which comprises hollow microspheres of aluminium silicate and a binder, the hollow microspheres presenting an alumina content of equal to or less than 38% in weight. 
     
     
         12 . The method according to  claim 11 , wherein the aluminium silicate presents an alumina content of 20 to 38%. 
     
     
         13 . The method according to  claim 11 , wherein the riser base comprises non-fibrous fillers, selected from the group formed by oxidable metals, oxidants, and inorganic fluorinated fluxes. 
     
     
         14 . The method according to  claim 11 , wherein the insulating and/or exothermal composition comprises a hot or a cold box cured binder. 
     
     
         15 . The method according to  claim 10 , wherein the exterior geometry of the riser base and the interior geometry of the auxiliary cavity of the mould is of a prismatic, truncated pyramidal, cylindrical, or semi-spherical shape.