Introduction to the Working Principle of Screw Metering Scale

The material is transported from the inlet to the outlet via a conveyor. An electronic weighing device (consisting of weighing levers, load cells, etc.) installed below the screw conveyor detects the weight of the material and generates a voltage signal proportional the load on the weighing lever, which is sent to a dynamic weighing meter. Simultaneously, a speed sensor installed at the tail of the screw conveyor inputs the speed signal of the conveyor' main shaft. The weight signal and speed signal are sent together to the controller for calculation, yielding the instantaneous flow rate and cumulative weight value. The control system outputs control signals through PID to dynamically adjust the speed of the feeding equipment, thereby achieving quantitative feeding and keeping the actual feeding flow rate stable near the set value.

Structural Composition

The core structure of the metering scale consists of a screw conveyor, a load cell, and an intelligent control system.

Mechanical Structure

The mechanical structure of the screw metering scale includes a support frame. fixed seats are welded to the top of the support frame, and removable bearing housings are provided on top of the fixed seats. A cylindrical body is located above the support frame, with an pipe and a discharge chute welded to its outer wall, communicating with its inner cavity. A rotatable auger shaft is coaxially installed within the cylindrical body, with screw blades welded its outer wall. The end of the sealing plate is equipped with a drive assembly to drive the auger shaft. Removable sealing flanges and sealing plates are provided at both ends of cylindrical body. Some designs utilize a double-layer screw tube, where the upper layer stabilizes the flow and transports material, while the lower layer transports and weighs. The flow-stabil screw can feature a variable pitch structure. Some designs employ a flexible connection structure.

Weighing System

The core components of the weighing system include load cells and weighing levers. sensor sends the full weight of the metering screw as a voltage signal proportional to the weighing load to the controller. Some patented technologies mention using a single high-precision tension sensor installed at golden force measurement point and support structure. A speed sensor is installed at the tail of the screw conveyor to detect the main shaft rotation speed signal.

Control System

The core controller the control system includes a weighing controller, such as an intelligent weighing controller. The control system outputs control signals through PID regulation to the variable frequency drive, dynamically adjusting the speed of the auger to achieve quantitative feeding. The control system is typically integrated into an electrical control cabinet and can easily communicate with host computers, DCS, and PLC systems