Apparatus for compacting molding sand using pressurized gas

Claim 1

An apparatus for compaction of molding sand by gas pressure, the apparatus comprising an enclosed gas space containing gas under pressure sealed by a sealing means and a mold area located therebelow, the mold area including a mold box closed at a bottom thereof by a pattern plate with a pattern thereon, a filling frame on a top of the mold area, a space above an upper surface of the molding sand heaped on said pattern, a piston plate is disposed a short distance above the upper surface of the molding sand, said piston plate forming said sealing means of said enclosed gas space and separating said space above the surface of the molding sand from the enclosed gas space, said piston plate being freely movable under the effect of the pressure of the gas in the enclosed gas space so that the gas disposed between the piston and the molding sand becomes compressed in a range of milliseconds and the sand undergoes compaction, a circumference of said piston plate is approximately equal to an inner cross sectional area of said filling frame, means for moving the piston plate to an initial position above the surface of the molding sand after the molding sand is compacted, and means for releasably locking the piston plate in the initial position.

Claim 2

An apparatus for compaction of molding sand by gas pressure, the apparatus comprising an enclosed gas space containing gas under pressure sealed by a sealing means and a mold area located therebelow, the mold area including a mold box closed at a bottom thereof by a pattern plate with a pattern thereon, a filling frame on a top of the mold area, a space above an upper surface of the molding sand heaped on said pattern, a piston plate is disposed a short distance above the upper surface of the molding sand, said piston plate forming said sealing means of said enclosed gas space and separating said space above the surface of the molding sand from the enclosed gas space, said piston plate being freely movable under the effect of the pressure of the gas in the enclosed gas space so that the gas disposed between the piston and the molding sand becomes compressed in a range of milliseconds and the sand undergoes compaction, a circumference of said piston plate is approximately equal to an inner cross sectional area of said filling frame, means for moving the piston plate to an initial position above the surface of the molding sand after the molding sand is compacted, and means for releasably locking the piston plate in the initial position.

Claim 18

An apparatus for compaction of molding sand by gas pressure, the apparatus comprising a flask, a pattern plate and pattern thereon, said pattern plate forming a lower floor of said flask, a filling frame placed on said flask and forming an enclosure in which there is an enclosed gas space above an upper surface of the molding sand heaped on said pattern, a piston plate positioned a small distance over said heaped sand and adapted to separate, at least at the beginning of said compaction under the action of gas in said enclosed gas space, the sand from the space over said piston plate, said piston plate being adapted to move freely while under the effect of gas pressure over said piston plate and thereby apply pressure to said enclosed gas space so that said gas in said enclosed gas space becomes compressed in a time period in an order of milliseconds and said molding sand undergoes compaction, said piston plate having an outline corresponding to an inner cross-section of the enclosure, and means for moving said piston plate back to an initial position thereof, said gas pressure is generated by producing an explosive gas mixture in said space over said piston plate, components of said gas mixture are mixed in said space over said piston plate by being blown therein in the form of a vortex so that they are mixed by free turbulent flow, and wherein free tubulence mixing means are placed in said space over said piston plate, said mixing means being composed of a downwardly widening mixing tube with a lower open end and tapering inwards at such open end and widening out in the form of a hollow ring at a top closed part thereof, and a tengential inlet opening in said hollow ring for at least one gas component.

Claim 19

An apparatus for compaction of molding sand by gas pressure, the apparatus comprising a flask, a pattern plate and pattern thereon, said pattern plate forming a lower floor of said flask, a filling frame placed on said flask and forming an enclosure in which there is an enclosed gas space above an upper surface of the molding sand heaped on said pattern, a piston plate positioned a small distance over said heaped sand and adapted to separate, at least at the beginning of said compaction under the action of gas in said enclosed gas space, the sand from the space over said piston plate, said piston plate being adapted to move freely while under the effect of gas pressure over said piston plate and thereby apply pressure to said enclosed gas space so that said gas in said enclosed gas space becomes compressed in a time period in an order of milliseconds and said molding sand undergoes compaction, said piston plate having an outline corresponding to an inner cross-section of the enclosure, and means for moving said piston plate back to an initial position thereof, said gas pressure is generated by producing an explosive gas mixture in said space over said piston plate, components of said gas mixture are mixed in said space over said piston plate by being blown therein in the form of a vortex so that they are mixed by free turbulent flow, and wherein free tubulence mixing means are placed in said space over said piston plate, said mixing means being composed of a downwardly widening mixing tube with a lower open end and tapering inwards at such open end and widening out in the form of a hollow ring at a top closed part thereof, and a tengential inlet opening in said hollow ring for at least one gas component.