Method and apparatus for metering and blending different material ingredients

A method of metering and blending different plastic material ingredients for discharge to an extrusion machine, comprising:

• metering to a common hopper a plurality of individual plastic material ingredients at controllable individual material discharge rates,
• blending the ingredients discharged from the individual material hoppers to form a blend in the common hopper,
• discharging the blended materials from said common hopper to said extrusion machine at a discharge rate,
• determining loss of weight of the blended materials in said common hopper due to discharge of the blended materials to the extrusion machine,
• determining the extrusion rate of the extrusion machine from the sum of the material discharge rates of the ingredients to the common hopper and the discharge rate of the blended materials from the common hopper to the extrusion machine, and
• controlling the material discharge rates of the ingredients to the common hopper in response to said determined extrusion rate as needed to maintain a preset recipe of the blended ingredients at said determined extrusion rate.

Apparatus for metering different material ingredients for discharge to a material processing machine, comprising:

• a plurality of metering devices for providing a controlled discharge rate of individual material ingredients, each of said metering devices comprising an individual material hopper for containing the material ingredient to be metered, first weighing means operably associated with each individual material hopper for detecting loss in weight of the material ingredient therein, a driven discharge device operably associated with each material hopper for discharging the material ingredient therefrom, and computer control means coupled to the weighing device for determining a material discharge rate and operably associated with the driven discharge device of each hopper for controlling the material discharge rate thereof,
• a common hopper for receiving the ingredients discharged by the metering devices,
• second weighing means operably associated with the common hopper for detecting a change in weight of the ingredients therein during discharge from the common hopper to the material processing machine, and
• a master computer control unit coupled to said individual computer control devices and to said second weighing means, said master computer control device being operative to determine the material processing rate of said machine based on the sum of said material discharge rates from the metering devices to the common hopper plus or minus the discharge rate of the ingredients from the common hopper to the processing machine and to control the material discharge rates of the metering devices as needed to maintain a preset recipe of said ingredients at said determined material processing rate.

Apparatus for metering and blending different plastic material ingredients for discharge to an extrusion machine, comprising:

• a plurality of metering devices for providing a controlled discharge rate of individual plastic material ingredients, each material metering device comprising an individual material hopper for containing the material ingredient to be metered, first weighing means operably associated with each individual material hopper for detecting a loss in weight of the ingredient therein, a motor-driven discharge device operably associated with each material hopper for discharging the ingredient therefrom, and a computer control device coupled to the first weighing means for determining a material discharge rate and operably associated with the motor-driven discharge device of each hopper for controlling the material discharge rate thereof,
• a cascade chamber for receiving and mixing the ingredients discharged by the metering devices to form a blend,
• a common hopper for receiving the blend of ingredients from the cascade chamber,
• second weighing means operably associated with the common hopper for detecting a change in weight of the blend therein during discharge from the common hopper to the extrusion machine,
• a master computer control unit coupled to said individual computer control devices and to said second weighing means, said master computer control device being operative to determine the extrusion rate of said machine based on the sum of said material discharge rates from the metering devices to the common hopper plus or minus the discharge rate of the blend from the common hopper to the extrusion machine and to control the material discharge rates of the metering devices to the common hopper as needed to maintain a preset recipe and substantially constant weight of said ingredients in the common hopper at said determined extrusion rate.