According to the invention, by setting the linear thermal expansion amount when a mold made of a molding sand is heated from a room temperature to 1000° C. to be not more than 0.9%, and the ratio (D/d) between the diameter of a slump (D) and the diameter of a slump cone (d) in a slump test of the molding sand having a hardening agent kneaded to be not less than 1.65, a molding sand preferable for use in a mold produced using the self-hardening type of three dimensional laminate molding sand mold, having low thermal expansibility preventing occurrence of a veining defect, and capable of forming a large and complicated shape can be obtained.

According to the invention, by setting the linear thermal expansion amount when a mold made of a molding sand is heated from a room temperature to 1000° C. to be not more than 0.9%, and the ratio (D/d) between the diameter of a slump (D) and the diameter of a slump cone (d) in a slump test of the molding sand having a hardening agent kneaded to be not less than 1.65, a molding sand preferable for use in a mold produced using the self-hardening type of three dimensional laminate molding sand mold, having low thermal expansibility preventing occurrence of a veining defect, and capable of forming a large and complicated shape can be obtained.

A method for manufacturing railcar coupler headcores includes providing a first corebox having internal walls defining at least in part perimeter boundaries of at least one rotor core cavity. The method further comprises at least partially filling the at least one rotor core cavity with a first sand resin to form at least one rotor core. The method also includes providing a second corebox having internal walls defining at least in part perimeter boundaries of at least one headcore cavity. The at least one rotor core is positioned within the second corebox. The method also comprises at least partially filling the at least one headcore cavity with a second sand resin to form at least one headcore.

A method for manufacturing railcar coupler headcores includes providing a first corebox having internal walls defining at least in part perimeter boundaries of at least one rotor core cavity. The method further comprises at least partially filling the at least one rotor core cavity with a first sand resin to form at least one rotor core. The method also includes providing a second corebox having internal walls defining at least in part perimeter boundaries of at least one headcore cavity. The at least one rotor core is positioned within the second corebox. The method also comprises at least partially filling the at least one headcore cavity with a second sand resin to form at least one headcore.

In one example, a sand core for use in a sand casting process includes a core body comprising a sand composition, the sand composition including sand and a binder; and a burnable fuse extending within the core body along a path and out of a surface of the core body, wherein the burnable fuse is configured such than when the fuse is ignited, the fuse burns within the core body to substantially remove the fuse and form a venting tunnel along the path within the core body with an opening in the surface.

The invention relates to a method for producing three-dimensionally layered shaped bodies by means of layer-by-layer construction using a resin component which contains at least one furane resin, and more than 5% by weight and less than 50% by weight monomer furfuryl alcohol, and an acid. The shaped bodies produced in this manner are suitable inter alia as casting molds and casting cores for metal casting.

The invention relates to a method for producing three-dimensionally layered shaped bodies by means of layer-by-layer construction using a resin component which contains at least one furane resin, and more than 5% by weight and less than 50% by weight monomer furfuryl alcohol, and an acid. The shaped bodies produced in this manner are suitable inter alia as casting molds and casting cores for metal casting.

The present invention provides a curing agent for casting a water glass, including an ester and an amorphous silicon dioxide obtained by a thermal decomposition of ZrSiO.sub.4; and the curing agent for casting the water glass does not contain water. According to the present invention, the curing agent for casting the water glass has a strong adhesion-enhancing effect and a long shelf life, and is easy to use.

The present invention provides a curing agent for casting a water glass, including an ester and an amorphous silicon dioxide obtained by a thermal decomposition of ZrSiO.sub.4; and the curing agent for casting the water glass does not contain water. According to the present invention, the curing agent for casting the water glass has a strong adhesion-enhancing effect and a long shelf life, and is easy to use.

Sand for a casting mold including sand, a binder, and an inorganic compound particle having poor water solubility and generating a gas, which is at least one of water vapor or carbon dioxide gas, by heat from a molten metal.