US Patent 7726380 Method for manufacturing sand mold

A method of producing a sand mold, comprising: after defining a mold space at least by a pattern plate, a flask, and a squeeze means, and after blow-charging molding sand held in a sand blowing device located above the mold space into the mold space by ejecting a first compressed air near sand ejecting ports of the sand blowing device thereby fluidizing the molding sand near the sand ejecting ports, while supplying a second compressed air to a surface of the molding sand held in the sand blowing device, moving the squeeze means toward the pattern plate, where in the pressure of the first compressed air and the period of time for supplying the first compressed air are adjusted to produce a good sand mold. To determine the period of time for ejecting the first compressed air, the distance of the movement of the squeeze feet toward the pattern plate is measured when the squeeze of the molding sand in the mold space is completed, and the difference between the measured distance and a target distance is calculated. The period is adjusted to be a shorter or lengthened one based on the result of the calculation.