Apparatus and apparatus for mixing and cooling molding sand

An improved apparatus for mixing and cooling molding sand for use in combination with a molding sand mixer having an elongated tube having an arcuate bottom, an elongated shaft extending axially within the tub, a series of paddles mounted on the shaft and extending radially toward the tub wall, power means for rotating said shaft, said paddles having blade and shank portions, at least said blade portions being disposed at an oblique angle to the tub axis to advance sand along the tub when the shaft rotates, the blade portions of the paddles having a greater circumferential extent than the shank portions, the aggregate circumferential extent of said blade portions at least almost filling the space around the periphery of said arcuate bottom of the tub when viewed in end elevation, there being substantial gaps between said shank portions of the paddles when viewed in end elevation, whereby the blade portions will substantially completely sweep the arcuate bottom of the tub, but some of the sand in the vicinity of the shanks may be missed by the shanks and be bypassed, said tub wall being lined with a resilient material and the paddle blade portions being provided with a resilient edge, said resilient material and said resilient edge coating to inhibit sand encrustation of said wall, the improvement comprising:

• an adjustable water supply means for variably supplying water to the molding sand in the molding sand mixer;
• a first set of output sensors having a temperature sensor and an electrical conductivity sensor;
• a second set of output sensors having a temperature sensor and an electrical conductivity sensor;
• a sand supply means for supplying molding sand to the molding sand mixer so that a substantially continuous flow of molding sand enters into and exits out of the molding sand mixer;
• an adjustable blower means for variably blowing air into the molding sand mixer;
• and a programmable logic control mechanism, programmed to independently adjust the water supply means and the blower means in response to input from the second set of output sensors, having a plurality of information inputs and command outputs;
• at least one command output being connected to the adjustable water supply means;
• at least one other command output being connected to the adjustable blower means;
• the first set of output sensors being in contact with a flow of molding sand coming from the sand supply means and entering into the molding sand mixer;
• the first set of output sensors measuring the temperature and moisture content of the molding sand entering into the molding sand mixer;
• the second set of output sensors being in contact with a flow of molding sand exiting the molding sand mixer;
• the second set of output sensors measuring the temperature and moisture content of the molding sand exiting the molding sand mixer;
• the first set of output sensors and the second set of output sensors being connected to the inputs of the programmable logic control mechanism;
• the programmable logic control mechanism being programmed to maintain the moisture content of the exiting sand in the range of 1-3.5%.

A process for controlling the temperature and moisture content of molding sand, the process using an improved apparatus for mixing and cooling molding sand, including a molding sand mixer that mixes molding sand, having an adjustable water supply means for variably supplying water to the molding sand in the molding sand mixer;

• a first set of output sensors having a temperature sensor and an electrical conductivity sensor;
• a second set of output sensors having a temperature sensor and an electrical conductivity sensor;
• a sand supply means for supplying molding sand to the molding sand mixer so that a substantially continuous flow of molding sand enters into and exits out of the molding sand mixer;
• an adjustable blower means for variably blowing air into the molding sand mixer;
• and a programmable logic control mechanism, programmed to independently adjust the water supply means and the blower means in response to input from the second set of output sensors, having a plurality of information inputs and command outputs;
• at least one command output being connected to the adjustable water supply means;
• at least one other command output being connected to the adjustable blower means;
• the first set of output sensors being in contact with a flow of molding sand coming from the sand supply means and entering into the molding sand mixer;
• the first set of output sensors measuring the temperature and moisture content of the molding sand entering into the molding sand mixer;
• the second set of output sensors being in contact with a flow of molding sand exiting the molding sand mixer;
• the second set of output sensors measuring the temperature and moisture content of the molding sand exiting the molding sand mixer;
• the first set of output sensors and the second set of output sensors being connected to the inputs of the programmable logic control mechanism;
• the programmable logic control mechanism being programmed to maintain the moisture content of the exiting sand in the range of 1-3.5% and a temperature of less than 120.degree. F., the process of the present invention comprising:
• a first step in which a constant and controlled volume of sand is furnished to the sand mixer;
• a second step in which the hot sand is mixed with water pursuant to a water addition formula prior to the introduction of air;
• a third step in which the sand and water are mixed with an air flow at a predetermined rate for a predetermined period of time;
• a fourth step in which the second set of output sensors measure the temperature and moisture content of the sand at a discharge end of the sand mixer;
• a fifth step in which the programmable logic control mechanism receives the temperature and moisture content of the sand at the discharge end of the sand mixer from the second set of output sensors and automatically effects air and water changes necessary to maintain the moisture content of the exiting sand in the range of 1-3.5% and a temperature of less than 120.degree. F.