Automation in dispensing materials is often performed using one or more weighing devices to quantify flow of a product at a particular location. For example, dispensation from a feed source can be monitored/controlled using a loss-in-weight feeder in which load cells on the feed source provide a quantitative signal indicating the actual material flow. In further downstream locations, belt scales can be used to provide a quantitative measure of material flow. Typical examples for such devices and methods are shown in U.S. Pat. Nos. 5,081,600 and 6,446,836, and 5,296,654.
While such devices and methods are often satisfactory for situations where the flow of the material must remain constant, currently known devices and methods have significant difficulties where the flow rate of a first material needs to be adjusted to a variable flow rate of a second material to retain a substantially constant ratio of the first and second materials. To circumvent problems associated with variable flow rates, the continuous flow rate may be at least temporarily converted to a batch process where a fixed quantity of the first material is added to the second material once the second material has reached a predetermined weight in a holding or otherwise accumulating device. While such batch processing advantageously increases accuracy of the ratio between first and second materials, batch processing is not always suitable for all operations.
Consequently, although various configurations and methods for dispensing materials are known in the art, all or almost all of them suffer from one or more disadvantages. Thus, there is still a need to provide improved methods and configurations for dispensing a material at a flow rate and quantity that is a function of the flow rate and quantity of another material.