The variable frequency dosing machine and the equal pressure mixer, weighing system and new conveying pump constitute the dosing system. The weighing module is installed under the powder bin and its function is to feed the metering device. The powder enters through the dosing feeder and adjusts the speed of the dosing feeder according to the comparison result of the instantaneous flow measurement value and the set value, so that the instantaneous value always tracks the set value, so as to realize the measurement and control of the feeding amount. The measured powder enters the powder conveying pipeline through the new conveying pump.

Speed dosing machine through the touch screen to complete the field dosing control and formula weight collection, the field operator only need to carry out the necessary manual intervention, you can complete the entire production, avoid human error, but also improve the production efficiency. With rich functions such as production monitoring, recipe management, batch statistics, alarm prompt and report printing, it is very suitable for real-time, multi-task control. Through the supporting communication interface, the relevant production information can also be uploaded to the data server or ERP to achieve information sharing.

The dosing machine adopts pulse width modulation (PWM) control method based on incremental PID algorithm, i.e., the duty cycle of PWM square wave is derived from the incremental PID algorithm. The regulation signal derived from the algorithm is output to the D/A holding circuit through the PB1 port (PWM) of ATmega8, and the amount of regulation determines the duty cycle of the PWM square wave. The D/A holding circuit converts the duty cycle of the PWM square wave into the corresponding 0-5V voltage value and outputs it after optoelectronic isolation, and the frequency inverter determines the screw rotation speed according to the voltage value so as to control the flow rate of materials.

Weighing and batching machine consists of big storage bin, bag filter, induced draft fan, balance valve, screw feeding device, storage hopper, etc. Powder sent by conveying system is sent to different big storage bins for storage according to models. When conveying the powder, the induced draft fan will automatically open and control the powder flying through the bag filter, the balance valve will automatically open to balance the pressure in the big storage bin, the screw feeding device at the bottom of the big storage bin will send the powder to the storage hopper to wait for further conveying to the weighing system, the balance valve will be automatically closed after the conveying is finished.

The measuring dosing machine adopts the pulse width modulation control method based on the incremental PID algorithm. The adjustment signal obtained by the incremental mode is output to the D/A holding circuit through the PB1 port. The D/A holding circuit converts the duty cycle of the PWM square wave into the corresponding 0-5V voltage value, and outputs it after photoelectric isolation.

Measuring and batching machine gives the control current of pump according to the ratio value, PLC outputs 4-20mA to control the pump and pump frequency converter, so that the flow control of discharging material is PID regulation, and according to the ratio of process requirements, the corresponding tracking flow is calculated and transmitted to PLC. PLC gives the control current of 4-20mA to control the frequency converter of the auxiliary material scale, so that the corresponding flow of the batching material is controlled in the range of the tracking flow most. The premixer, distribution screw machine and the umbrella fan are equipped with on-site shoulder and stop buttons, which are converted by remote control and connected to the central control room. The start-stop control of the equipment can be realized through the start-stop button on the lip distribution cabinet, or the start-stop button on the human-machine interface after the distribution process can also be manipulated. It can also realize the start/stop control by controlling PLC.