Abstract: The auxiliary shaft hoisting signal system is a crucial component of the auxiliary shaft hoisting electrical control system. Its performance directly impacts the safe operation of the hoist and even the overall safe production of the coal mine. This paper designs a hoisting signal system for a mine auxiliary shaft using a PLC controller as the core. The system design block diagram and functions are presented, and the working principle is explained. The system has been initially tested in several coal mines in Pingdingshan City. Results show that the system operates normally, has stable performance, accurate signal transmission, and reliable display, effectively ensuring the reliability of hoisting safety and laying a solid foundation for safe coal mine production.
Henan Province is a resource-rich province, with Pingdingshan City being particularly rich in coal resources. Transforming the traditional coal industry, changing its image, improving modern management levels of enterprises, and enhancing coal mine safety will enable it to gain a competitive edge in the market. The application of computer control and network technologies in the coal industry has changed its technological and industrial structure, increased coal production and safety, and improved the automation and management levels of enterprises.
The auxiliary shaft hoisting signal system is a crucial component of the auxiliary shaft hoisting electrical control system, and its performance directly impacts the safe operation of the auxiliary shaft hoist. With the development of computer technology and electronic components, a digital computing electronic device specifically designed for industrial applications—the Programmable Logic Controller (PLC)—has emerged. It employs a programmable memory to store instructions for performing logical, sequential, timing, counting, and arithmetic operations, and can control various types of machinery or production processes through digital or analog inputs and outputs. Because PLCs and their related peripherals are easily integrated into industrial control systems, expanding their functionality, they have become the most widely used industrial control devices today, an indispensable core control component in electromechanical control. With the increasing demands for automation in industrial production, more reliable PLCs have been applied to various systems in the coal industry. This paper proposes a design scheme for a mine auxiliary shaft hoisting signal system based on a PLC.
1 Overall Design
Figure 1 shows the design block diagram of a mine auxiliary hoisting signal system with PLC as its core. This system mainly consists of a PLC controller, signal inputs, signal outputs, a signal box at the mine entrance, a signal box at the bottom of the mine, a signal box in the winch room, and a protection system.
The PLC controller is the core component of the entire system. It has advantages such as flexible function changes, simple programming, automatic fault detection, low noise, high reliability, strong anti-interference ability, complete hardware support, comprehensive functions, wide applicability, low workload in system design, installation and debugging, convenient maintenance, easy modification, small size, light weight, and low energy consumption.
The signal input mainly includes the hoist's destination, position, and functional signals. Among them, the hoist signals include ore hoisting, material hoisting, personnel hoisting, upward movement, and downward movement signals.
The signal output mainly includes downlink audio and display signals, uplink audio and display signals, material lifting, ore lifting, and personnel lifting counting signals, and television display signals.
The wellhead signal box mainly includes Chinese character displays and sound prompts for various hoisting signals, as well as button detection for various signals. It performs interlocking functions for various signals at this level and for downhole signals, while also sending corresponding signals to the winch room.
The bottom hole signal box mainly includes Chinese character displays and sound prompts for various hoisting signals, as well as button detection for various signals. It completes the sending of corresponding signals to the wellhead and simultaneously performs the interlocking function for various signals at this level.
The winch room signal box mainly displays digital and Chinese characters and provides audio prompts for hoisting signals at the wellhead and bottom, as well as storing and displaying the previous signals. It also performs functions such as interlocking the safety circuit with emergency stop signals, issuing stroke change signals, and interlocking with stop signals.
The protection system mainly includes fault signal prediction, accident stop signal, and emergency stop signal. When a fault occurs in the hoist control system, the protection system sends a signal, which is then sent to the winch room by the PLC controller to perform corresponding operations, playing a very important role in the safety of the coal mine.
2 System Analysis
2.1 System Functions
The designed PLC-based mine auxiliary shaft hoisting signal system can achieve the following functions: 1) hoisting signals have digital display function; 2) hoisting commands have Chinese character display function; 3) emergency stop alarm function and emergency stop extension function; 4) the signals above and below ground must be consistent before the machine can be started; 5) underground signals can only be transmitted to the winch room through the signals above ground, and cannot be directly transmitted to the winch room; 6) at the accident point and the stop point, the signals are directly transmitted to the winch room from above ground and below ground to stop the winch operation; 7) realize the directional interlocking function; 8) realize the fast and slow interlocking function.
2.2 System Working Principle
The working principle diagram of the system is shown in Figure 2, and the distribution of its dot signals is shown in Table 1.
The system works as follows:
Once the hoist is in position, the electromagnetic sensor at the wellhead transmits a positioning signal to the PLC controller. After processing by the PLC controller, an operating command is sent to the winch room. The signalman can then operate the hoist, opening the safety door, lowering the rocking platform, and activating the car stopper. The signal sequence is: lower wellhead → upper wellhead → winch room. After the hoist is fully loaded, all wellhead locks are released: the safety door is closed, the rocking platform is raised, and the front car stopper is deactivated.
1) Hoisting quickly
The lower wellhead makes two initial markings. After processing by the PLC controller, X1 moves twice, shifting the shift register two bits to the left, activating internal relay R20, and triggering Y8 twice. The lower wellhead display shows the signal count as "2", and both the upper and lower wellhead bells ring twice simultaneously. Upon receiving the marking signal, the upper wellhead marking device X3 marks "2", shifting the shift register two bits to the left, activating Y0, and causing the motor to move rapidly upwards. Simultaneously, due to Y0 interlocking, circuit Y7 is activated, and the red indicator light illuminates.
When marking the mark at the upper wellhead, relays Y4, Y5, and Y6 are activated, and the electric bells at the lower wellhead, upper wellhead, and hoist room ring. The number of rings is the same as the number of marks. At this time, Y9 is activated, triggering the upper wellhead display circuit to display "2". When the well surface is reached, the X4 mark register of the stop switch is reset, the coil is de-energized, the hoist stops, and the display is reset.
2) Hoist rapid descent
The lower wellhead is marked three times. After being controlled by the PLC controller, the shift register is shifted to R2, R0-R2 are connected, R1 and R20 are de-energized, and R21 is energized. The corresponding contacts close, the upper and lower wellhead bells ring, and the lower well displays "3". Upon hearing the instruction, the upper well begins marking, and the process is the same as above. The hoist is then started.
3) The elevator slowly ascends.
When the machine is running at slow speed in the positive direction, the "4" mark is used to indicate slow speed. After processing by the PLC controller, the display shows "4". The interlocking effect of R4 prevents the other relays from working, and the circuit operation is switched through the external contacts connected to ZJ3.
4) The elevator descends slowly.
That is, the machine is driven slowly in the opposite direction. When it goes down into the well, the "4" mark indicates slow speed. After processing by the PLC controller, the display shows "4". The interlocking effect of R4 prevents the other relays from working, and the circuit operation is switched through the external contacts connected to ZJ3.
3. Conclusion
After its design, the system has been initially tested in some coal mines in Pingdingshan City. Since the trial, the system has been operating normally, with stable performance, accurate signal transmission, and reliable display, effectively ensuring the reliability of safety and laying a solid foundation for safe production in coal mines.
