| 摘要 |
CONTROL APPARATUS FOR PLASTIC BLENDING MACHINERY Apparatus for controlling the discharge of fluent, particulate plastic material from a supply to a blending hopper comprises a delivery tube having a discharge orifice at its lower end that may be closed by a circular valve which seats against the delivery tube to close and seal the orifice. The valve is movable from its closed position to a fully open position in which a relatively large clearance exists between the discharge orifice and a body of material supported at its angle of repose on the valve. Material thus is able to cascade through the clearance to a receiving hopper whose weight is monitored by one or more load cells coupled to a microprocessor. When the weight of the receiving hopper increases to a selected value due to the delivery of material thereto, the valve is moved from its fully open position to a partially open position in which the aforementioned clearance is reduced substantially, thereby materially slowing the rate of discharge of material from the supply. When a predetermined quantity of material has been delivered to the receiving hopper, the valve is returned to its fully closed position, thereby terminating the discharge of material. The delivery tube has a chamber therein adjacent the discharge orifice that is devoid of material as long as material flows through the discharge orifice, and in which material supported atop the valve may be accommodated when the valve moves to its closed position. |
