Analyzing The Application Of Automatic Control Technology In Commercial Concrete Mixing Plants.

Automatic control principles have a wide range of applications and have been used in concrete production since the 1980s. In recent years, domestic construction machinery manufacturers have developed new products with a high degree of automation, further improving the quality of concrete mixing. Currently, commercial concrete companies in Zhengzhou use highly automated mixing plants, which feature excellent and stable product quality, low production costs, and good environmental performance. The mixing plant's computer control system is used for automated electronic batching of concrete production and control devices. It consists of an industrial computer, an operating console, and a power distribution cabinet. It can automatically and continuously control the weighing, feeding, mixing, and discharging of various materials according to a given formula. This improves upon the previous method of on-site concrete production, reducing noise and dust pollution.
1. Industrial Computer The industrial computer, as the upper-level control unit, is equipped with a MOXA four-port serial expansion card, a 64-input/64-output opto-isolated digital input/output card, and a parallel expansion card. It uses the RS232C communication protocol for production process control and input.
 2. Weighing Instrument Composed of a DC power supply, A/D converter, microprocessor, keyboard, display, serial interface, memory, and opto-isolated control interface.
3. Control Execution Unit/Process Input Unit Located in the operating console and power distribution cabinet, the control output signals from the industrial computer and weighing and batching system are amplified by transistors to drive 24V intermediate relays, which then drive various loads.  In addition, various production process signals and alarm signals are acquired by the 1/3 board in the industrial computer after level conversion, and then analyzed and processed by software.
 4. Operating Console and Power Distribution Cabinet The power distribution cabinet, composed of circuit breakers, contactors, and thermal relays, provides drive and short-circuit protection and motor overload protection for various equipment motors. The operating console has an automatic/manual conversion switch, various function buttons and switches, and emergency stop buttons. The various buttons and switches on the operating console form a process flow simulation screen. In automatic operation, various equipment and production processes are controlled by the industrial computer software. The process flow simulation screen on the operating console displays the operating status of the equipment. In manual operation, the operating console can be used to debug equipment or manually control production.
5. Upper-level Control System Developed in Delphi under the Windows environment, the program consists of modules such as production, parameter setting, recipe management, material management, customer management, vehicle management, engineering project management, and statistical report management. It is easy to operate and powerful in functionality.
6. Lower-level Control System (Weighing and Batching Machine) It consists of a main program, interrupt service program, and other subroutines. The software adopts a modular design for communication. Display, A/D conversion, data processing, and control functions are primarily achieved by receiving the weighing values of various materials sent by the industrial control computer via serial communication. After receiving the start weighing command from the industrial control computer, the weighing and batching machine performs weighing and batching according to the program, and simultaneously sends the program progress and net weight of the materials to the industrial control computer to complete the weighing and batching process.
7. Software Description The concrete mixing plant uses a program to control the production process. This program generally includes system management, production and transportation management, and production statistics management. Conclusion The application of automatic control principles in automated concrete mixing plants has led to rapid development in the construction industry. Significant improvements have been made in terms of quality and construction speed, and more importantly, it has freed up labor. The widespread promotion of ready-mixed concrete is highly beneficial to urban construction and the development and innovation of automatic control theory.