1. Basics and principles of control technology
The precise control of the running speed of the trolley and the car by the Shipbuilding Gantry Crane depends first on the advanced control technology principles. The variable frequency speed regulation technology is the key, and its core lies in adjusting the motor speed by changing the power supply frequency of the motor. In the operation system of the crane, the inverter, as an important speed regulation device, receives instructions from the control system. When the speed of the trolley or the car needs to be adjusted, the control system sends a signal to the inverter, and the inverter changes the output voltage and frequency according to the set frequency to drive the motor to achieve speed change. For example, when lifting precision parts, the speed of the trolley or the car needs to be accurately controlled at a lower level. At this time, the inverter lowers the power supply frequency and the motor speed decreases accordingly. Vector control is also an important part. It decomposes the stator current of the AC motor into the excitation current that generates the magnetic field and the torque current that generates the torque, and controls them separately. This is just like the control method of the DC motor, which can achieve more accurate torque control and thus accurately adjust the speed. In practical applications, when the load of the crane changes, the vector control can dynamically adjust the torque according to the load size to ensure the stability of the speed and avoid speed fluctuations affecting the accuracy of the lifting operation.
2. Accurate monitoring of speed sensors
In order to achieve precise control, high-precision speed sensors are essential. In the trolley and car system of Shipbuilding Gantry Crane, encoders are commonly used speed sensors. The incremental encoder converts the rotational motion into a pulse signal by installing it on the motor shaft or transmission component. For each rotation of the motor, the encoder generates a fixed number of pulses. The control system can accurately obtain the real-time speed of the motor by counting and analyzing the number of pulses per unit time. For example, during the movement of the trolley, the encoder continuously feeds back pulse signals to the control system, and the control system accurately grasps the running speed of the trolley based on these signals. The absolute encoder is more advantageous. It can not only provide speed information, but also determine the absolute position of the motor. Even if it is restarted after an unexpected power outage, the precise position of the motor can be immediately known, providing more comprehensive data for speed control. The data provided by these sensors is the basis for precise control, and their accuracy and reliability directly affect the quality of speed control.
3. Coordination and Optimization of Control System
The control system of Shipbuilding Gantry Crane plays a role of coordination and optimization in precise speed control. The programmable logic controller (PLC) is the core of the control system. The PLC receives feedback data from the speed sensor, the operator's operating instructions, and other related monitoring data, such as lifting weight, running stroke, etc. Internally, the PLC runs complex control programs, which are written according to the operating characteristics and precise control requirements of the crane. When receiving a speed adjustment instruction, the PLC will comprehensively consider various factors, such as current speed, target speed, load conditions, safety limits, etc., and generate appropriate control instructions through precise mathematical operations and logical judgments. For example, when the trolley needs to move quickly to a specified position, the PLC will calculate the frequency adjustment value required by the inverter based on the current speed and position, combined with the impact of the load on the speed, to achieve fast and precise acceleration. At the same time, the PLC also has powerful fault diagnosis and processing capabilities. Once abnormal speed or other faults are found, measures can be taken quickly, such as emergency braking, alarms, and recording fault information to ensure the safe and stable operation of the crane.
4. Calibration and maintenance to ensure accuracy
To maintain accurate control of the running speed of the trolley and the car for a long time, calibration and maintenance are essential. Regular calibration of the speed sensor is the basis for ensuring accuracy. Since the crane operates in a harsh industrial environment, the encoder may be affected by dust, vibration, temperature changes and other factors, resulting in measurement errors. Therefore, it is necessary to regularly calibrate the encoder using professional calibration equipment to ensure that the pulse signal it outputs accurately reflects the actual speed and position of the motor. For the control system, especially the control program in the PLC, it is also necessary to regularly check and optimize. With the increase in the use time of the crane and the change in the operating conditions, the original control program may need to be adjusted. At the same time, the speed control equipment such as the frequency converter should be maintained to check whether its parameter settings are correct and whether the electronic components are aged or damaged. During the maintenance process, attention should also be paid to the performance of the motor, such as the winding resistance, insulation resistance and other parameters of the motor, because changes in motor performance will also affect the accuracy of speed control. Only through rigorous calibration and comprehensive maintenance can the Shipbuilding Gantry Crane maintain accurate control of the speed of the trolley and the car for a long time.
