Method of producing sand mold

Abstract

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.

1 . A method of producing a sand mold, comprising:
 after defining a mold space by at least 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,   wherein 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, the difference between the measured distance and a target distance is calculated, and based on the result of the calculation the period of time for ejecting the first compressed air is made shorter or lengthened to change a condition for blow-charging the molding sand in the mold space.   
     
     
         2 . The method of producing a sand mold of  claim 1 , wherein the mold space is defined by a pattern plate, a flask placed on the pattern plate, a filling frame placed on the flask, and multiple squeeze feet as the squeeze means inserted in the filling frame from above. 
     
     
         3 . The method of producing a sand mold of  claim 1 , wherein the mold space is defined as upper and lower mold space halves by a pattern plate, upper and lower flasks holding the pattern plate therebetween, and upper and lower squeeze feet as the squeeze means inserted in openings of the upper and lower flasks, respectively, the openings being opposite the other openings thereof located at the pattern plate. 
     
     
         4 . The method of producing a sand mold of  claim 1 , wherein the pressure of the first compressed air is 0.05-0.18 MPa. 
     
     
         5 . The method of producing a sand mold of  claim 1  or  4 , wherein the pressure of the second compressed air is 0.05-0.18 MPa. 
     
     
         6 . The method of producing a sand mold of  claim 3 , wherein one or more vent holes are formed in the match plate, an air discharging port is formed in each of the upper and lower flasks, and wherein at a initial stage of blow charging of the molding sand into the upper and lower mold space halves, the air vent ports are closed, while the vent hole or holes in the match plate is opened to discharge the compressed air therefrom to sufficiently compact the molding sand near the vent hole or holes, and at a last stage of the blow charging the air discharge ports are opened to discharge the compressed air therefrom to sufficiently compact the molding sand near the air discharge ports and to facilitate to discharge the compressed air from the upper and lower flasks. 
     
     
         7 . The method of producing a sand mold of  claim 3  or  6 , wherein the pressures of the first and second compressed airs and the period of time to supply the first and second compressed airs to the sand blowing device are adjusted relative to volumes of the upper and lower mold space halves based on measurements of a produced sand mold. 
     
     
         8 . A method of producing a sand mold, comprising:
 after defining upper and lower mold space halves by upper and lower flasks, each having a sand blow-in port in a sidewall thereof, a pattern plate disposed between the upper and lower flasks, and upper and lower squeeze means having a plurality of squeeze feet to be inserted in openings of the upper and lower flasks, the openings being opposite the other openings thereof located at the match plate, and after blow-charging molding sand from a sand blowing device into the mold space halves 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,   the method comprising the steps of:   positioning the upper and lower mold space halves at a vertical position under the sand blowing device so that the sand blow-in ports mate with the sand ejecting ports of the sand blowing device; and   ejecting the first compressed air of 0.05-0.18 MPa to the molding sand near the sand ejecting ports to fluidize the molding sand near the sand ejecting ports; and   supplying the second compressed air to a position above the molding sand held in the sand blow device, thereby pressing and blow-charging the molding sand into the upper and lower mold space halves.   
     
     
         9 . The method of producing a sand mold of  claim 8 , further comprising a step of controlling discharging the compressed airs from the upper and lower mold space halves when the molding sand is blow-charged into the upper and lower mold space halves. 
     
     
         10 . The method of producing a sand mold of  claim 8  or  9 , wherein the pressure of the second compressed air is 0.05-0.18 MPa. 
     
     
         11 . The method of producing a sand mold of  claim 8 ,  9  or  10 , wherein the first and second compressed airs are supplied to the sand blowing device with the pressure of the first compressed air being kept greater than that of the second compressed air and with the pressures of the both the first and second compressed airs being made greater stepwise over time, and wherein the compressed airs are discharged from the sand blowing device with the pressure of the first compressed air being kept greater than that of the second compressed air after the pressure in the position above the molding sand in the sand blowing device becomes a target value. 
     
     
         12 . The method of producing a sand mold of any one of  claims 8 - 11 , wherein one or more vent holes are formed in the match plate, an air discharging port is formed in each of the upper and lower flasks, and wherein at a initial stage of blow charging of the molding sand into the upper and lower mold space halves, the air vent ports are closed, while the vent hole or holes in the match plate is opened to discharge the compressed air therefrom to sufficiently compact the molding sand near the vent hole or holes, and at a last stage of the blow charging the air discharge ports are opened to discharge the compressed air therefrom to sufficiently compact the molding sand near the air discharge ports and to facilitate to discharge the compressed air from the upper and lower flasks. 
     
     
         13 . The method of producing a sand mold of any one of  claims 8 - 12 , wherein the pressures of the first and second compressed airs and the period of time to supply the first and second compressed airs to the sand blowing device are adjusted relative to volumes of the upper and lower mold space halves based on measurements of a produced sand mold.