Batch weighing/supply device, and operating method therefor

An operating method for a batch weighing/supply device in which an inner tube is provided above a circular bottom plate on a shared central axis and with a predetermined gap therebetween, an outer tube is provided on the circular bottom plate concentrically with the inner tube such that an annular passage is formed between the inner and outer tubes, a raw material in the inner tube is paid out to the annular passage side from a lower end of the inner tube at a predetermined angle of repose, a plurality of rotary blades are provided so as to rotate on the circular bottom plate about the central axis, a discharge port for the raw material conveyed through the annular passage by the rotary blades is provided in the annular passage, and weighing means is provided to weigh the raw material discharged through the discharge port,

• wherein a primary height adjustable scraper provided on an upstream side of the discharge port in order to reduce the quantity of conveyed raw material when lowered, a secondary height adjustable scraper provided on a downstream side of the primary height adjustable scraper and directly adjacent to the discharge port on the upstream side thereof in order to further reduce the quantity of conveyed raw material after the quantity has been reduced by lowering the primary height adjustable scraper, a sliding gate for stopping the raw material from dropping down through the discharge port, control means for drive-controlling the rotary blades, the primary and secondary height adjustable scrapers, and the sliding gate on the basis of a weighed value from the weighing means, and storage means for storing a set value of batch weighing, a primary set value, and a secondary set value are provided in the annular passage,
• an upstream-side edge portion of the discharge port is formed as an inclined side edge that intersects the rotary blades, and
• the control means executes the steps of:
• performing a normal weighing operation for causing the raw material to drop down so as to be supplied through the discharge port, in which the primary height adjustable scraper and the secondary height adjustable scraper are both in raised positions and the raw material is supplied by driving the rotary blades to rotate, until the weighed value reaches the primary set value;
• performing a primary reduction operation, in which the quantity of conveyed raw material is reduced by lowering the primary height adjustable scraper and the rotation speed of the rotary blades is reduced, from a point at which the weighed value reaches the primary set value;
• performing a secondary reduction operation, in which the quantity of conveyed raw material is further reduced by lowering the secondary height adjustable scraper and the rotation speed of the rotary blades is further reduced, from a point at which the weighed value reaches the secondary set value;
• and
• stopping the rotary blades from rotating and stopping the raw material from dropping down through the discharge port by closing the sliding gate from a point at which the weighed value reaches the set value.