Automation plays a crucial role in the global economy. In industries like food processing and packaging, there is a pressing demand for efficient and flexible production systems. Traditional systems controlled by electromagnetic relays suffer from issues such as high complexity and slow response. PLCs are widely adopted due to their advantages like accuracy, ruggedness, and reliability. This project is centered around using Mitsubishi PLC to design and implement an automatic bottle filling and conveying system for the filling machine, aiming to enhance the performance of the filling machine, boost production efficiency, minimize human intervention, cut costs, and strengthen the flexibility and reliability of the overall system.
Hardware Part
PLC (Mitsubishi): As the core control unit of the filling machine's automation system, the PLC (Mitsubishi) functions similar to a computer. It manages the manufacturing process of the filling machine, offering diverse analog and digital input and output interfaces. It processes signals, converts data, and based on user - defined programs, scans the inputs and precisely controls the outputs, which are essential for the smooth operation of the filling machine.
Photoelectric Sensor: The photoelectric sensor, with a working voltage of 6 - 36V DC and an output current of 300mA, and a response frequency of 0.5kHz, is a key component in the filling machine. By using a photoelectric transmitter and receiver, it can detect the distance and presence of objects. In this project, a diffused photoelectric sensor is installed on the filling machine to detect plastic bottles on the conveyor belt. Its features like long - distance measuring, quick response time, non - contact sensing, easy adjustment, color identification, and high resolution ensure accurate bottle detection during the filling process of the filling machine.
Solenoid Valve: The solenoid valve is an electromechanical device that is vital for the filling operation of the filling machine. It uses an electric current to generate a magnetic field, which in turn controls the opening and closing of the valve. This mechanism precisely controls the pouring of liquid into the bottles at a specific time. Comprising parts such as the valve body, inlet port, outlet port, coil/solenoid, coil windings, lead wires, plunger or piston, and spring, the solenoid valve is a critical part of the filling machine's liquid - filling mechanism.
Relay and Motor: The relay, an electrically - operated switch relying on the magnetic field strength of the coil, is used in conjunction with the motor in the filling machine. It controls the motor through its normally open (NO) and normally closed (NC) states. The 12V DC motor, equipped with a gearbox to adjust torque and speed, powers the conveyor belt of the filling machine. It enables the movement of bottles under the filling valve before filling and transports the filled bottles away after the filling process is completed.
Conveyor Belt: The conveyor belt of the filling machine is made of a rubber composite. Its properties such as stretchability, resistance to various environmental factors like moisture and chemicals, non - breakability, and smooth surface make it suitable for the continuous operation of the filling machine. It ensures the stable and efficient transportation of bottles during the filling process.
Software Part
Project Operation Method: The operation of the filling machine begins when the start button is pressed. This action activates the DC motor, setting the conveyor belt of the filling machine in motion. As the bottles are conveyed along the belt, when the first bottle reaches the position under the solenoid valve, the photoelectric sensor on the filling machine detects the bottle and sends a signal to the PLC. The PLC then commands the motor to stop, halting the conveyor belt, and simultaneously activates the solenoid valve to start the filling process. The filling time is regulated by a timer in the PLC, with the solenoid valve remaining open for t seconds. Once the bottle is filled, the solenoid valve closes, and the motor restarts, moving the filled bottle away from the filling area via the conveyor belt. If another bottle is detected under the valve, the entire filling process is repeated. Pressing the stop button terminates the operation of the entire filling machine system.
Ladder Programming: Ladder programming is selected to operate the PLC in the filling machine due to its simplicity and suitability for handling Boolean signals. The program is developed using GX Works3 software. In this program, inputs such as the start button (X0), stop button (X1), and sensor (X2) are defined, and outputs like the solenoid valve (Y0) and motor (Y1) are specified. Each rung of the ladder program has a specific logic control function for the filling machine, ensuring the coordinated operation of all components during the filling process.
System Testing and Conclusion: After thorough testing, this automation system for the filling machine has proven to be effective. It significantly improves the production efficiency of the filling machine, ensures consistent quality and quantity of the filled liquid in each bottle, reduces the need for human intervention, cuts down on costs, and meets the production requirements of small - scale enterprises. Overall, it successfully achieves the expected design goals for the filling machine.
