The rapid development of the real estate industry has led to the flourishing of the ceramic and wood industries. However, the production and processing environment of ceramics is heavily polluted, and the large-scale investment in wood has led to a sharp decline in forest greening. With the increasing awareness of human environmental protection, more and more new material products have emerged. A woodworking machinery in Guangde County, Anhui Province adopts a brand new polyethylene low foaming calcium plastic board, which has the advantages of high mechanical strength, good buffering performance, strong temperature adaptability, and radiation resistance. But it is prone to variability in the production and processing process, and requires high printing standards. Therefore, there are extremely high requirements for the driving part. This article describes the application of Dongli Kechuang CT1 series frequency converter in the field, and elaborates on Dongli Kechuang's application plan in the wood traction machine industry.
Introduction to the Electrical Control Principle of Plate Traction Machine
Composition of the electrical control system for CNC engraving machine
Introduction to Traction Machine Function: The function of the board traction machine is to produce plastic boards with fixed thickness, fixed width, and special printing. After the board is formed, it is used for real estate construction. The first part of the processing is the plastic extruder, which mixes raw materials and forms them into thermoplastic shapes before extruding them. The sheet pulling mechanism pulls out the extruded sheet. However, due to the uneven material output from the front-end extruder, it may result in some sheets being wide and others being narrow. Therefore, a position sensor needs to be installed for width signal feedback.
Control requirements
1. High low-frequency torque and high speed stability accuracy: Because the actual operating speed is not high, it is necessary to ensure constant torque output, even at low speeds, to ensure a large output; It is necessary to ensure that the thickness of the board is consistent, so the speed stability accuracy must be high, otherwise it will result in uneven thickness of the board.
2. Width positioning control: It is necessary to ensure consistent width, therefore width positioning is required. Position information can be sampled through position sensors as feedback for the width signal of the board. The frequency converter determines whether to increase or decrease the speed by receiving width signals to understand the current quantity of incoming materials.
3. Composite frequency setting: In most cases, the standard speed can meet the requirements, so a basic and appropriate fundamental frequency setting needs to be given. Occasionally, uneven incoming materials require frequency adjustment. The frequency converter outputs a composite frequency through PID adjustment, and the superimposed frequency ensures response to the current width information, ensuring quick response even in case of material abnormalities.
4. Controllable frequency adjustment: Slow speed adjustment can lead to slow system response and uneven thickness of the board; Adjusting the speed too quickly can cause large fluctuations in rotational speed and uneven printing surface. Therefore, the superposition frequency needs to be limited by a lower limit.
The start stop method of the frequency converter is terminal start stop, which means that the DI1/DI command is given to the frequency converter through an external button through a digital input terminal to achieve the start stop of the motor.
Considering that rapid braking may be required in case of emergency system failure to avoid mechanical damage, the emergency stop function is implemented through DI3 as the terminal. The fault signal of the frequency converter is output through the programmable relay terminal, and the system receives the fault signal to avoid mechanical damage caused by misoperation when the frequency converter fails. After the fault is cleared, the fault lock can be released through the reset terminal.
Due to the system using a combination of two frequency sources, there may be some instability during the testing process. Therefore, a single action switch has been added, which can be used to switch the frequency source during debugging mode through a single action button.
The system speed regulation method is a combination of two frequency combinations, with the main setting being given by the keyboard, the secondary setting being given by PID, and the secondary setting being given by a small adjustment amount. A smaller upper and lower limit can be set.
Key point explanation: As the speed of the front-end feeding mechanism is basically constant, the adjustment amount of the auxiliary adjustment part does not need to be too large. If the auxiliary frequency adjustment is too small, the response to the position signal will be slow, which will result in uneven board width and thickness; If the auxiliary adjustment frequency is too high and the speed changes too much per unit time, it will cause abnormal printing on the board, resulting in patterns that are either deep or shallow. Therefore, the upper and lower limits of PID adjustment need to be set reasonably.
Technical Description of CT100 Series Inverter
The CT100 frequency converter of Shenzhen Dongli Kechuang Technology Co., Ltd. is based on a DSP control system and adopts domestically leading PG free vector control technology, combined with multiple protection methods, which can be applied to asynchronous motors and provide excellent driving performance. The product has greatly improved customer usability and environmental adaptability in terms of air duct design, hardware configuration, and software functionality.
Technical Features
◆ Accurate motor parameter self-learning: Accurate self-learning of rotating or stationary motor parameters, easy debugging, simple operation, providing higher control accuracy and response speed
Vectorized V/F control: automatic stator voltage drop compensation and slip compensation, ensuring excellent low-frequency high torque and torque dynamic response even in VF control mode.
◆ Software current and voltage limiting function: Good voltage and current limiting, effectively limiting key control parameters to reduce the risk of inverter failure.
◆ Multiple braking modes: Provides multiple braking modes to ensure stable, accurate, and fast system shutdown.
Strong environmental adaptability: With a high overall overheating point, independent air duct design, and thickened three proof paint treatment, it is more suitable for situations where woodworking machinery has high humidity and a lot of wood powder.
◆ Speed tracking restart function: Achieve smooth and impact free starting of the rotating motor.
◆ Automatic voltage adjustment function: When the grid voltage changes, it can automatically maintain a constant output voltage.
Comprehensive fault protection: protection functions for overcurrent, overvoltage, undervoltage, overtemperature, phase loss, overload, etc.
Conclusion
The power of the sheet metal traction machine is very small, and the control scheme is not very complex, but it is sensitive to the accuracy of speed adjustment and feedback of sheet metal width information, so it requires very fine adjustment. The CT100 series frequency converter is a high-performance open-loop vector frequency converter newly developed by Shenzhen Dongli Sci Tech Innovation Technology Co., Ltd. Its excellent performance and rich functions have made it very well applied in CNC sheet metal traction machines and received excellent praise from customers.