The weighing hopper utilizes PLC interlocking technology to ensure the smooth progress of dosage. After the batching starts, the industrial control machine sends a signal to PLC to start adding materials, PLC controls the frequency converter to drive the motor to add materials quickly, the industrial control host continuously reads the weighing data of the weighing instrument through the serial port, when the weight value is close to the set value, the industrial control host sends the control instruction to PLC to stop adding materials, PLC controls the frequency converter to add materials slowly, by estimating the residue of raw materials on the conveyor in advance, the difference between the set value and the actual added material and the difference between the set value and the actual added material will be displayed in real time, which is the same with the actual added material. By estimating the residual value of raw materials on the conveyor in advance, when the difference between the set value and the actual feeding and the residual value of raw materials on the conveyor are comparable, PLC will issue a stop command, which will be executed by the frequency converter, thus controlling the motor to stop, and after stopping, there is no residual value of raw materials on the conveyor, and the accuracy of the dosing is in accordance with the requirements.

The dosage scale consists of an industrial computer, a PLC, an industrial weighing instrument, a frequency converter, a vibration motor, a mixing machine, a sensor, a conveyor belt and other components. PLC provides human-computer interaction interface, completes the functions of control information input, data management, data display, storage, statistics and reports, etc. According to the operator's instruction, it reads a certain numbered recipe, and then according to the proportion and sequence of ingredients in the recipe, PLC sends out the instruction to start the batching, which makes PLC able to start a specific frequency converter.

Batching scale to achieve material transfer, batching control, formula design, production data management and other functions. And it can realize the collection control of multiple ingredients through the network. With PLC as the next machine ingredients, once the production plan is completed in the entire production process, the computer will weigh each raw material according to the plan, no longer need manual intervention. In this process, the worker only takes the material, and the computer checks the weight through the data sent by the electronic weighing, which reduces the work burden of the worker and improves the work efficiency.

The electrical part of pneumatic batching scale is mainly composed of weighing sensor, weighing instrument, programmable controller (PLC), inverter, industrial computer and printer. In the process of dynamic weighing, the weight signal of the weight sensor on the quantitative weighing hopper is received. When the weight of the material in the hopper reaches each set value, the output I/O quantitative signal to the PLC. PLC collects the quantitative output signal of the weighing instrument, and controls the output frequency of each frequency converter through PLC, so as to control the thickness and fine feeding amount of the corresponding vibration feeder and the switching door action of each weighing hopper.

The weighing hopper system measures through the weighing module, and compares the measured value with a given value (the given value is determined by the ratio of material A and material B) and the measured value, and then transmits the result of the comparison to the PLC's A/D analog module, and then transmits the control signal (4-20mA current signal) through the PLC's D/A analog module to the electric regulating valve, and then controls the servo motor in the electric regulating valve to open the electric regulating valve to control the size of material B inlet. The control signal will control the servo motor in the electric control valve to adjust the opening degree of the electric control valve, so as to achieve the control of the feeding size of material B.

The weighing belt conveyor is used for the quantitative feeding of bulk materials, the feeding process is a continuous feeding of the belt, the feeder will be from the user feed silo or other feeding equipment to transport the material and through the weighing bridge for weight detection, at the same time mounted in the tail pulley of the speed sensor to detect the speed of the belt. The measured weight and speed signals are sent to the accumulator for differential processing and display the instantaneous flow in tons per hour for comparison, and according to the size of the deviation from the output of the corresponding signal value (PID signal), through the frequency converter to change the speed of the motor to change the feeding volume, so that it is a certain amount of time with the set value, so as to complete the control of a constant feeding flow.

Belt scale is composed of four parts, such as weighing frame, weighing sensor, velocity sensor and display instrument. The weighing instrument integrates the speed signal and the weighing signal to obtain the instantaneous flow rate and the cumulative amount. The speed sensor is directly connected to the large diameter speed measuring drum and provides a series of pulses, each representing a belt movement unit, and the frequency of the pulse is proportional to the belt speed. The weighing instrument receives signals from the weighing sensor and the speed sensor, and obtains an instantaneous flow value and cumulative weight value through integral calculation, and displays them respectively.

The construction of an electronic belt scale consists of a bracket and a belt, which is attached to the bracket at each end. When an object is placed on the electronic belt, the object exerts a force vector onto the belt, and the belt is tensioned as a result. The belt sends out an electronic signal with a frequency related to the degree of tension. When the belt is stressed, the electronic components inside will determine the weight of the object through the output signal of the pressure sensor through the computer processing system.

The electronic belt scale transmits the weight signal of the material on the belt and the speed signal of the belt to the on-site totalizer through the front channel weighing equipment and the rear channel weighing equipment installed on the conveyor. Inside the on-site totalizer, the weight signal is converted to a digital quantity by AD and transformed into a weight value by the built-in microcontroller; the speed pulse is transformed into a speed value by the built-in microcontroller and multiplied by the weight value to obtain the instantaneous flow rate; the two channels accumulate the instantaneous flow rate at the same time to obtain the totalized amount of the material in the two channels respectively, which is saved in the internal non-volatile memory. When the two channels are normal, the remote display adopts the average value of the accumulated quantity of the two channels, and if one of the channels fails, the normal one will be displayed.