The weighing Feeding machine is composed of a pre-feeding bin, pneumatic feeding valve, hopper scale, precision screw conveyor, speed-regulating drive part, industrial control machine and electrical control part, etc. It lifts the material to be processed to the pre-feeding bin through the pneumatic conveying device. When the material is fed to the set weight, the pneumatic conveying device stops feeding and the pneumatic feeding valve automatically opens. The material enters the hopper scale from the pre-feeding bin. When the material in the hopper scale is added to the rated weight, the pneumatic feeding valve automatically closes, the screw Feeder starts, and the system enters the metering and feeding state. When the material in the pre-feeding bin drops to the minimum material level, the pneumatic conveying device automatically feeds the material into the pre-feeding bin. When the material in the hopper scale drops to the set minimum material level, the feeding valve automatically opens, and the pre-feeding bin fills the material bin. The industrial control computer displays the material quantity in both bins at any time.

Before the system starts working, the process requirement quantity is manually input into the industrial control computer as the standard quantity. When the screw conveyor feeds materials, the reduction of the material in the silo within a unit of time is the actual feeding quantity, which is transmitted to the industrial control computer through the weighing module and simultaneously displayed as the actual material quantity in the silo at that time. The actual feeding amount is constantly compared with the preset standard amount. The deviation is randomly adjusted by the industrial control computer to the rotational speed of the precision screw conveyor, making the total amount approach zero. At the same time, the corresponding cumulative amount is calculated and displayed. While the pre-feeding bin is feeding materials to the hopper scale through the feeding valve, the control system automatically switches to the volumetric feeding mode and feeding state (in the design, the volumetric feeding time is shortened as much as possible to improve the feeding accuracy). When the hopper scale has completed feeding, the pneumatic feeding valve automatically closes to stop feeding, and the system automatically enters the metering feeding state again. This cycle continues Intermittent feeding is carried out on the hopper scale, with volumetric metering feeding and metering feeding alternating, ensuring continuous and stable feeding during the operation of the system and achieving high-precision automated and precise feeding.

The on-site data is collected in real time by using the analog input template in the PLC. The main collected contents include the actual weighing value, screw speed, current parameters, and the operating status of each device. Based on the different flow ranges of each screw scale, the actual values are calculated, and the average value of the converted values is taken to minimize the flow fluctuation, facilitating the application of the values to the PID loop regulation and ensuring the stability of the regulation. The display of material level adopts a method of one channel on-site and one channel in the main control room, which facilitates real-time monitoring of the material level in the silo by both parties. This ensures that on-site personnel can take measures to add materials when the material level is low, preventing the occurrence of material shortage.

The frequency of the feeding hopper is controlled by two methods: PLC output and weighing instrument setting. When the PC feeding machine malfunctions, it can be switched to different weighing instrument outputs, ensuring the continuity of production. When the PLC outputs, the on-site hopper frequency converter is controlled through three methods: proportioning setting, flow setting and frequency setting. When the operator selects the proportioning on the operation screen, they only need to input the total flow rate of the ingredients and the proportioning ratio of each sub-scale. Then, the feeding amount of each scale can be automatically calculated and tracked and adjusted based on this feeding amount. This method reduces the workload of operators in calculating the flow rate of each sub-scale based on the ratio, and the calculation is accurate. Flow setting is to control the flow of each sub-scale through the flow setting area on the screen. This setting method should be used when tuning the PID parameters of each scale. The frequency setting principle is to fix the output frequency of the frequency converter of the on-site hopper. This setting method should be used when conducting physical weighing. At a given frequency, the discharge volume of each screw scale is compared with the total weighing value of the screw scales, and the flow rate of the screw scales is corrected based on the difference. This method is both intuitive and convenient.