Overview
Belt scale batching scales are real-time controllers used to measure and control the speed and material flow of belt conveyors. They are mainly used in industries such as power plants, mines, metallurgy, chemicals, and feed processing. Due to the harsh working environments, large voltage fluctuations in the power grid, long production lines, and complex control processes in these industries, belt scale batching systems are multivariable and nonlinear time-varying systems, requiring reliable control, accurate batching, and strong anti-interference capabilities. Therefore, we researched a control system based on automation software to solve the problem of accurate calculation.
Two-belt scale control system
1. Working principle
A hopper sits atop the belt of a belt conveyor. As the belt runs, a feeding device transports material along with it. The conveyor belt is driven by a slip-ring motor. A speed sensor provides an electrical signal with a frequency proportional to the belt speed. A load sensor below the belt provides a voltage signal proportional to the material on the belt. The belt feed scale controller receives the speed signal from the speed sensor and the weight signal from the load sensor, calculates the instantaneous and cumulative flow rates of the material on the belt, displays the results, and compares them with a given flow rate value. Through fuzzy control, it outputs a current control signal to control the speed of the slip-ring motor, thereby stabilizing the material flow rate at the given value.
2. Control System Composition
The belt scale control system consists of two main parts: hardware and software. The hardware comprises belt scale instruments, an industrial control computer, data acquisition cards, and communication cards, distributed across various production lines. The belt scale instruments provide real-time cumulative weight, instantaneous flow rate, and belt speed information for bulk materials on the production line. The communication cards connect the belt scale instruments (RS-485 interface) to the industrial control computer. The data acquisition cards collect other signals required on-site and provide them to the industrial control computer. The system's human-machine interface (HMI) processes the data from the belt scale instruments and data acquisition cards, displays the processing results promptly, and serves as the system's interface. The software part is the belt scale control system software. Its function is to enable users to statistically manage materials based on the process flow and on-site conditions, using information provided by the instruments and acquisition cards. It then informs users of the results, generates various reports according to user needs for easy access and printing, produces various charts to aid data analysis, and provides network query functionality for real-time data access by management at all levels within the factory.
2.1 Human-Machine Interface Control System
Create process flow diagrams according to on-site requirements, and display trends, alarms, belt operation, etc. on human-machine interface to more intuitively monitor and control on-site equipment and understand the operating status in real time;
2.2 Reporting System
The system can automatically calculate the daily output value and generate daily reports and reports, facilitating statistical analysis of the data for a specific day in future work.
2.3 Alarm System
Zijinqiao software offers five levels of alarm settings. When collected data exceeds the set limit, a corresponding alarm will be generated to promptly alert operators to the abnormality. Zijinqiao software also provides a historical alarm retrieval function, allowing users to search alarm records for any given day.
III. Conclusion
This system has small flow error, stable and reliable operation, simple control algorithm, can be modified online according to site requirements, and is easy to debug and maintain.
