Conveyor calibration technique

摘要

A method is disclosed for calibrating a bulk material weighing and metering conveyor of the endless belt type providing a variable frequency signal indicative of feed rate. In such a conveyor system, a belt speed signal and a tare-adjusted weight signal are multiplied to provide a product signal that is converted into a periodic pulse signal whose frequency indicates the feed rate (net weight per unit of time) of the material being metered by the conveyor. In a first calibration step, the weight of the empty conveyor belt is measured over one belt revolution by counting the periods of the feed rate indicative pulse signal. This count is then used to establish a tare weight reference value. With the tare weight reference value established and the feed rate signal compensated therefor, a second calibration step is performed wherein the periods of the feed rate indicative pulse signal are again counted for a known increment of belt travel with a known net weight of material for such increment of belt. This second count is compared to the theoretically expected count, such comparison being used to determine the accuracy of the indicated feed rate and to effect necessary calibration adjustments if needed.