The weighing hopper feeder is a dynamic weighing and feeding method for the hopper scale. In the quantitative weighing device, an integrated mechanical and electrical equipment driven by an electric motor (commonly known as a screw feeder motor) is placed between the silo and the hopper. The electronic control device realizes the dynamic quantitative weighing of powder and granular materials. The powder and granular materials in the silo rotate with the rotation of the screw feeder mechanism and enter the hopper. There are three strain-type weighing modules between the hopper and the scale frame. When the set weight value is reached, the screw feeder motor is turned off to stop feeding, and the hopper door is opened to discharge the material, thus completing a dynamic weighing and quantitative feeding process.

The structural layout of the Quantitative hopper scale is as follows: grab → hopper scale → feeding hopper → feeding belt conveyor → electric three-way → wharf belt conveyor. It is composed of a hopper scale, an electro-hydraulic arc-shaped gate, a weighing module, a threshold type support steel structure, etc. The hopper scale is not firmly fixed on the steel structure of the ship unloader, but a set of sill support steel structure is designed for this hopper scale. The frame-supported steel structure is composed of the support beam of the hopper scale, the door legs on the river side and the door legs on the land side of the pulley, as well as the connecting reinforcement beam.

The hopper feeder mainly consists of a spiral feeder, a buffer hopper, a hopper scale, a variable frequency motor, an electromagnet, etc. The feeder is composed of two spiral propellers of different diameters. During the high-speed loading stage, to increase the loading speed, the double-wound wheel operates at high speed simultaneously; during the low-speed fine adjustment stage, the clutch is used to disengage the large wheel and the small wheel is used alone for loading. The entire loading process is equipped with the stepless speed regulation feature of the variable frequency motor, thus enabling precise loading.

The hopper screw scale can achieve precise material weighing by controlling the screw rotation speed. This can further improve the weighing accuracy. The prerequisite for improving the weighing accuracy is to enhance the accuracy of controlling the screw number. A toothed belt drive can be adopted. Through the small pulley in a tower-shaped structure and by changing the position of the toothed belt on the pulley, the screw rotation speed can be accurately calculated, and this can further improve the precision.

The hopper feeder achieves fast and slow feeding by controlling the input signal size of the frequency converter. Firstly, it performs fast feeding. Once the feeding reaches a certain value, the feeding speed gradually slows down. The stopping time of the feeding motor is adjusted by adjusting the starting torque of the frequency converter. By using multiple frequency converters to control multiple motors, the starting torque of each frequency converter can be adjusted separately to adjust the stopping time of each motor, thereby improving the weighing accuracy of various materials.

The weighing hopper system automatically calculates the set value and stop-sifting value of the hopper scale before loading. Before each material loading, the hopper scale calculates automatically according to the set weight of the hopper scale and the weight needed to compensate for the previous weighing error by the program. To reduce the loading deviation caused by mechanical inertia and the residual vibration of the feeding equipment during feeding, the weighing system must send a signal indicating that the hopper is full to stop the feeding equipment in advance. The full signal is sent when the weight of the hopper reaches the stop-sifting value.

The hopper screw scale is composed of an upper computer, PLC, instruments and a frequency converter. The PLC adopts Siemens S7-300 and exchanges data with the upper computer via industrial Ethernet. The detection instruments and actuating elements are directly connected to the I/ O module of the PLC. The entire line is controlled by PLC programs. Programming uses ladder diagrams and is uniformly programmed in combination with the external characteristics of the controlled electrical system to achieve sequential control, logical control, interlocking and interlocking. Manual and automatic operation modes can be switched.

The automatic control system of the negative pressure hopper scale automatically adds two or more types of materials in a certain weight ratio into the hopper scale, and discharges the materials automatically after weighing reaches the predetermined requirements. It adopts automated control to realize automatic control and supervision of processes such as raw material loading, weighing measurement, vacuum feeding, dispersion and transportation. The dispersion time and cylinder number can be selected and adjusted on the computer according to production requirements. The opening and closing of the motor equipment and the opening and closing of the feeding valve are all controlled by the computer during the process.

The hopper formula scale uses a laser distance sensor for measurement. The distance sensor transmits continuous electrical signals to the PLC. The PLC outputs corresponding analog signals to the pilot proportional directional valve according to the preset acceleration and deceleration positions and workstations to control the start and stop of the feeding hopper and the running speed. The discharging process and the material sticking situation of the hopper are detected by the weighing module. During the running discharging process, when the electrical signal of the weight sensor is less than the preset weight of the hopper skin, the discharging is ended and the discharging door is closed. When the weight of the hopper skin exceeds a certain weight, an alarm signal is issued to prompt the operator to clean it in time.