Method and apparatus for combining high speed horizontal and high speed vertical continuous mixing of chemically bonded foundry sand

Apparatus for combining high speed horizontal and high speed vertical continuous mixing of sand and binder ingredients for mold making purposes comprising:

• a pair of side-by-side horizontally extending cylindrical first mixing chambers having contiguous upwardly facing inlet openings adjacent their rearward ends and contiguous downwardly facing discharge openings adjacent their forward ends;
• first feeder means for introducing sand into the first mixing chambers including a hopper which extends vertically above the first mixing chambers and defines a conduit which communicates with their inlet openings, and first gate means normally sealing the conduit and actuable to open the conduit to allow a predetermined amount of sand supplied to the hopper to flow into each of the first mixing chambers;
• second feeder means for introducing a first liquid binder ingredient into one of the first mixing chambers and a second liquid binder ingredient into the other one of the first mixing chambers, the second feeder means including pipe means adjacent the rearward ends of the first mixing chambers for injecting liquid binder ingredient into the chambers, means for supplying liquid binder ingredient to the pipe means, and means for supplying air under pressure to the pipe means for forcing the liquid binder ingredient into the first mixing chambers;
• a pair of first shafts extending horizontally and centrally one through each of the first mixing chambers, means for rotatably supporting the first shafts including front bearing plates which seal the forward ends of the first mixing chambers and means for detachably mounting the front bearing plates to the forward ends of the first mixing chambers, each first shaft carrying helical blades at each end for conveying sand towards the intermediate portions of the first mixing chambers, a plurality of fixed similarly pitched paddle blades for mixing the sand and the first liquid binder ingredient in the one first mixing chamber to form a first preliminary mixture and for mixing the sand and the second liquid binder ingredient in the other first mixing chamber to form a second preliminary mixture and for conveying the first and second preliminary mixtures forwardly, and a plurality of radially extending flinger blades for discharging the first and second preliminary mixtures out of the first mixing chambers through their discharge openings;
• first motor means for rotating the first shafts at from about 300 revolutions per minute to about 1500 revolutions per minute;
• a vertically extending second mixing chamber positioned underneath the forward portions of the first mixing chambers, the second mixing chamber having an inlet opening at its upper end sufficiently large to receive the first and second preliminary mixtures discharged from the first mixing chambers and a discharge opening at its lower end;
• means for detachably securing the second mixing chamber underneath the forward portions of the first mixing chambers so that the inlet opening of the second mixing chamber is underneath the discharge openings of the first mixing chambers;
• a second shaft extending vertically and centrally through the second mixing chamber, means for rotatably supporting the second shaft, a plurality of blades fixed to the second shaft including upper blades extending vertically along substantially the entire length of a cylindrical first inner surface of the second mixing chamber to mix the first and second preliminary mixtures and scrape them from the first inner surface during rotation of the second shaft, vertically spaced support arms for fixing upper blades to the second shaft and lower blades which spiral downward and inward from the lower ends of the upper blades to further mix the first and second preliminary mixtures and scrape them from a frusto-conical second inner surface of the second mixing chamber to form a final mixture and to impel the final mixture downwardly through the discharge opening of the second mixing chamber during rotation of the second shaft;
• second motor means for rotating the second shaft at from about 300 revolutions per minute to about 800 revolutions per minute;
• and
• second gate means normally sealing the discharge opening of the second mixing chamber and actuable to open the same to allow the final mixture to be discharged from the second mixing chamber.