Method for making upper and lower molds and an apparatus therefor

Abstract

The purpose of this invention is to provide a method for making upper and lower molds and an apparatus therefor that can prevent the resulting molds from being warped and match-plates from being broken. The method of this invention comprises the step of holding a match-plate 1 between cope and drag flasks 2 and 3, inserting upper and lower squeezing means 4 and 5 into the respective openings of the cope and drag flasks 2 and 3, which openings are opposite to the match-plate 1, so as to define upper and lower molding spaces, supplying molding sand to the upper and lower molding spaces, and then causing the upper and lower squeezing means 4 and 5 to move forward to the match-plate 1 so as to squeeze the molding sand and make upper and lower molds, wherein during the step of causing the upper and lower squeezing means to move forward to the match-plate the difference between the squeezing pressures of the upper and lower molding spaces is kept within a predetermined tolerance.

1 . A method for making upper and lower molds comprises the steps of holding a match-plate between cope and drag flasks, inserting upper and lower squeezing means into the respective openings of the cope and drag flasks, which openings are opposite to the match-plate, thereby defining upper and lower molding spaces, then supplying molding sand to the upper and lower molding spaces, and causing the upper and lower squeezing means to move forward to the match-plate for squeezing the molding sand in the upper and lower molding spaces,
 wherein during the step of causing the upper and lower squeezing means to move forward to the match-plate the difference between the squeezing pressures of the upper and lower molding spaces is kept within a predetermined tolerance.   
   
   
       2 . An apparatus for making upper and lower molds is an apparatus for holding a match-plate between cope and drag flasks, inserting upper and lower squeezing means into the respective openings of the cope and drag flasks, which openings are opposite to the match-plate, thereby defining upper and lower molding spaces, then supplying molding sand to the upper and lower molding spaces, and causing the upper and lower squeezing means to move forward to the match-plate for squeezing the molding sand in the upper and lower molding spaces, comprising
 upper and lower driving means that cause the respective upper and lower squeezing means to move forward to and backward from the match-plate,   upper and lower squeezing pressure-measuring means that are installed on the upper and lower driving means and that measure the respective pressures when the sand is squeezed, and   a command-transmitting means that determines the difference between the values measured by the upper and lower squeezing pressure-measuring means and compares it to a predetermined tolerance, and if the difference is larger than the tolerance, the command-transmitting means will send a command to the driving means so as to stop causing the driving means that has the larger pressure to move forward until the difference falls within the predetermined tolerance.   
   
   
       3 . The apparatus for making the upper and lower molds of  claim 2 ,
 wherein the upper and lower driving means are hydraulic cylinders with a hydraulic power unit, and the upper and lower squeezing pressure-measuring means are pressure sensors that are installed on the hydraulic power unit.   
   
   
       4 . The apparatus for making the upper and lower molds of  claim 3 ,
 wherein the pressure sensors are load cells that measure the force of the hydraulic cylinders.   
   
   
       5 . The apparatus for making the upper and lower molds of  claim 2 ,
 wherein the upper and lower driving means are electric cylinders with a power supply unit, and the upper and lower squeezing pressure-measuring means are voltmeters that are installed on the power supply unit.   
   
   
       6 . The apparatus for making the upper and lower molds of  claim 5 ,
 wherein the upper and lower squeezing pressure-measuring means are load cells that measure the force of the electric cylinders.   
   
   
       7 . The apparatus for making the upper and lower molds of  claim 2 ,
 wherein the upper and lower driving means are electric cylinders with a power supply unit, and the upper and lower squeezing pressure-measuring means are ammeters that are installed on the power supply unit.   
   
   
       8 . The apparatus for making the upper and lower molds of  claim 7 ,
 wherein the upper and lower squeezing pressure-measuring means are load cells that measure the force of the electric cylinders.