1. Summary
This article introduces the application scheme of Oerlikon Drive's vector frequency converter with torque sensor instead of torque motor in the winding equipment of plastic machinery and printing machinery. Due to its wide speed / torque setting range and smoother running characteristics, More and more are used in plastic packaging and printing companies.
(1) Overview of torque motor
Torque motor is a special motor with soft mechanical characteristics and wide speed range. Torque motors include: DC torque motors, AC torque motors, and brushless DC torque motors.
(2) Construction principle of torque motor
When the load increases, the motor speed can be automatically reduced, and the output torque increases to maintain balance with the load. Torque motors have high stall torque and low stall current, and can withstand the stall operation for a certain period of time. Due to the high rotor negative current, large losses, and large heat generation, especially during low-speed operation and stalling, the motor is equipped with an independent axial or centrifugal fan on the rear end cover (small output torque) 100 machine seats and below) except for forced ventilation and cooling, the torque motor is equipped with thyristor control device, which can adjust the voltage and speed, the speed range can reach 1: 4, and the speed change rate is ≤10%. The characteristics of this series of motors make it suitable for winding, unwinding, stalling and speed regulation and other applications, and are widely used in industrial fields such as textile, wire and cable, metal processing, papermaking, rubber, plastics and printing machinery.
(3) Main features of torque motor
The characteristic of torque motor is that it has soft mechanical characteristics and can be blocked. When the load torque increases, it can automatically reduce the speed and increase the output torque. When the load torque is a certain value, the speed can be adjusted by changing the motor terminal voltage. But the speed adjustment rate is not good! Therefore, a speed measuring device is added to the motor shaft and equipped with a controller. The output voltage of the speed measuring device is compared with the voltage given by the controller to automatically adjust the terminal voltage of the motor. stable!
It has the characteristics of low speed, large torque, strong overload capacity, fast response, good linearity of characteristics, and small torque fluctuations. It can directly drive the load and save the reduction gear, thereby improving the operating accuracy of the system. In order to obtain different performance indicators, the motor has three different structural forms: small air gap, medium air gap, and large air gap. The small air gap structure can meet the requirements of general use accuracy, and the advantage is lower cost. The large air gap structure, due to the increase in air gap , Eliminates cogging effect, reduces torque fluctuations, basically eliminates non-linear changes in reluctance, motor linearity is better, electromagnetic air gap is increased, armature inductance is small, electrical time constant is small, but manufacturing cost is high ; Medium air gap structure, its performance index is slightly lower than the motor of the air gap structure, but much higher than the motor of the small air gap structure, and the volume is smaller than the motor of the air gap structure, the manufacturing cost is lower than the motor of the air gap structure.
(4) Torque motor application
In industries such as machinery manufacturing, textiles, papermaking, rubber, plastics, metal wires and wires and cables, products need to be wound on reels (dishes). The diameter of the winding is larger from the beginning to the end. In order to keep the tension of the object to be uniform (that is, the linear speed is constant), it is required that the rotating speed of the reel be smaller and the winding force is larger. Application characteristics: winding, uncoiling (brake constant power characteristics), stepless speed regulation, etc.
1. Winding
In the processing of wire and cable, textile, metal processing, paper making, etc., winding is a very important process. The diameter of the reel gradually increases when the product is wound. It is very important to maintain the tension of the rolled product throughout the process, because excessive tension will thin or even break the wire diameter, or cause uneven thickness of the product. If the tension is too low, it may cause slack winding. In order to keep the tension constant during the winding process, the output torque of the motor driving the reel must also increase when the diameter of the product wound onto the reel increases, and at the same time to keep the linear speed of the wound product constant, The speed of the reel must be reduced accordingly, and the mechanical characteristics of the torque motor can meet this requirement.
2. Uncoiling (brake constant power characteristic)
Unwinding is also called unwinding, unwinding, unwinding, etc. In industrial production, it is sometimes necessary to transport the product wound on the drum to the next process. During the conveying process, it is required to apply a tension to the product in the opposite direction of the transmission, and at the same time it is required to keep the linear velocity and reverse tension of the product transmission constant with the change of the cylinder diameter, which requires the motor to have a constant braking power characteristic.
3. Stepless speed regulation
The mechanical characteristics of the torque motor can achieve higher rigidity under the control of modern servo drives, so it can replace the original mechanical transmission device to achieve direct drive. At present, there are already CNC rotary tables and CNC swing angle milling heads that use torque motors as the core power components. These products are not as good as the mechanical transmission device in terms of volume-to-power ratio, but due to their advantages of no transmission gap, no wear, high transmission accuracy and efficiency, etc., they have begun to promote the use of precision equipment.
4. Stalling
In some special occasions, the motor is sometimes required to maintain a static torque for a period of time, such as the cable must be kept tight at the beginning of winding; the forging clamping device for large forging presses. Due to the large impedance of the torque motor; its blocked current is small, and forced ventilation is used at the same time, so it can meet the requirements of locked rotor within a certain period of time. The allowed stall time should be according to the value calibrated on the nameplate. If a longer stall time is required, a larger torque motor can be selected, which can be obtained by reducing the terminal voltage of the torque motor.
5. Other
Torque motors can also be flexibly applied according to their various characteristics. For example, if they have the characteristics of a DC series motor, they can be partly used instead of DC motors. If the rotor has high resistance characteristics, the starting (blocking) torque is large, so it can be applied. In the opening and closing gate (valve) door and the drag system with large resistance torque; it can also be used for its characteristics of large starting (blocking) torque, small starting (blocking) current, and high mechanical strength of the solid rotor. It is used in various machines with frequent forward and reverse rotation or other similar actions.
Second, the configuration of F3000 instead of torque motor
1 F3000 series inverter
2 Variable frequency vector motor
3 Rotary encoder
3. Inverter parameter setting and wiring
In the actual working process, the most commonly used is to only use analog adjustment to control the torque, and the speed limit control uses a fixed value, which is not lower than the maximum working frequency required by the equipment.
4. The working process of F3000 inverter driving variable frequency vector motor
After F3000 frequency converter and frequency conversion motor replace torque motor, it can fully achieve the function of torque motor:
1 When starting with no load, adjust the torque control potentiometer to adjust the motor torque, usually the customer will have an empirical value, then the motor speed will rise to the set speed limit.
2 When the winding starts with the load, the winding motor will reduce the speed due to loading. When the tension of the plastic film from the traction point to the winding shaft reaches the torque adjusted by the motor, the speed remains unchanged and the winding continues. If the speed is increased, then the tension of this section of film will be reduced, less than the current torque of the motor, then the speed of the inverter will be accelerated until it is consistent. vice versa.
3 If the traction motor stops working, the winding motor will also stop due to the excessive tension of the film, and the frequency of the inverter will be reduced to zero, while maintaining the existing torque size so that the film will not relax. Once the traction motor starts to work, the winding motor will accelerate and decelerate accordingly.
V. Conclusion
The torque motor is replaced by Oerui frequency converter to achieve constant tension winding and unwinding function, which has superior torque characteristics, and greatly improves the reliability of the equipment, overcomes the heating situation of the motor, saves electrical energy, and can also reduce the fault of the motor . Therefore, more and more customers began to use frequency converters to replace torque motors to achieve transverse tension control.
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Parking locks, also called parking space locks, parking barriers.
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Features
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