Views: 2009 Author: Site Editor Publish Time: 2022-01-06 Origin: Site
With the increasing development of technology, modern sheet metal processing, especially the bending process requirements are increasingly high, there are different technical needs for equipment and processing efficiency, and for environmental protection and energy saving, both enterprises and the state have strict control, so compared to hydraulic bending machine, electro-hydraulic servo system control bending machine is increasingly accepted by major customers.
Based on the update of servo technology, this article will discuss how servo technology is applied to bending machines.
CNC press brake electro-hydraulic servo system is a kind of automatic control system established according to the principle of hydraulic transmission by using electro-hydraulic servo mechanism. In this system, the movement of the actuator changes with the change of the control signal.
Working principle and composition
Electro-hydraulic servo valve is a kind of automatic control valve, which is both electro-hydraulic conversion component and power amplifier component. Its function is to convert small power analog signal input into high power hydraulic energy flow and pressure output with the change of electric signal size and polarity, and fast response, so as to realize the control of hydraulic actuator displacement, speed, acceleration and force. The electro-hydraulic servo valve is usually composed of an electrical and mechanical converter, a hydraulic amplifier and a detection feedback mechanism.
The compact design eliminates the need for external piping, and the system is mounted directly on the cylinder, making it cleaner and leak-free compared to electric drives alone.
The system converts the electrical signal from the CNC controller into a mechanical linear motion. To accomplish this motion, signals are transmitted between the machine's CNC controller and the motor drive controller. The synchronous cylinders control the tracking and fast running according to a predefined working curve. A speed-controlled servo pump unit is used to drive and control the position of the bending tool and the bending force during the bending process.
The electro-hydraulic servo bending machine is controlled by the controller through two sets of servo bi-directional pump system to control the flow and pressure of Y1 and Y2 cylinders respectively, and the oil from the upper cavity of the cylinder is directly pumped into the lower cavity of the cylinder to realize the lifting of the upper die, and the oil pump is reversed to pump the oil from the lower cavity of the cylinder directly into the upper cavity of the cylinder to realize the sheet metal bending. The synchronization of the left and right of the upper die of the machine is controlled by two sets of servo bi-directional pumps respectively. The machine not only has high precision, energy saving, low noise, but also is more stable and reliable, using less oil, which is conducive to the manufacture of large stroke ultra-high speed bending machine.
Q: So how to choose DC servo system and AC servo? What is the difference?
A: DC servo motors are divided into brushed and brushless motors.
Brush motor is low cost, simple structure, large starting torque, wide speed range, easy control, requires maintenance, but easy maintenance (change carbon brushes), generates electromagnetic interference, and has requirements for the environment. Therefore it can be used in cost-sensitive general industrial and civil applications.
Brushless motor is small in size, light in weight, large output, fast response, high speed, small inertia, smooth rotation and stable torque. The control is complex, easy to realize intelligent, and its electronic phase change is flexible, can be square wave phase change or sine wave phase change. The motor is maintenance-free, with high efficiency, low operating temperature, low electromagnetic radiation, long life, and can be used in various environments.
AC servo motor is also brushless motor, divided into synchronous and asynchronous motor, at present, synchronous motor is generally used in motion control, which has a large power range and can do a lot of power. Large inertia, low maximum rotation speed, and rapidly decreases as the power increases. Therefore, it is suitable for doing low speed and smooth running applications.
Conclusion: We use the best AC servo motor for our ZFY series electro-hydraulic press brake.
Q: When using electro-hydraulic bending machine to pay attention to the problem?
A: ZFY feel the following checks before operation:
1). Whether the power supply voltage is appropriate (overvoltage is likely to cause damage to the drive module); for the DC input + / - polarity must not be connected to the wrong, drive the controller on the motor model or current setting value is appropriate (not too large at the beginning.
2). Control signal lines firmly connected, industrial sites are best to consider shielding (such as the use of twisted pair.
3). Do not start with the need to connect all the lines connected to only the most basic system, after good operation, and then gradually connected.
4). Be sure to figure out the grounding method, or the use of floating air not connected.
5). Start running within half an hour to closely observe the state of the motor, such as whether the movement is normal, sound and temperature rise, find the problem immediately stop to adjust.
Q: I want to control servo motor directly through communication, is it possible?
A: Yes, it is convenient, but it is only a matter of speed, for applications that do not require high response speed. If you require fast response to control parameters, it is best to use a servo motion control card, which generally has DSP and high speed logic processing circuitry on it to achieve high speed and high precision motion control. Such as S acceleration, multi-axis interpolation, etc.
Q: How about using a switching power supply to power stepper and DC motor systems?
A: Not recommended, especially for large torque motors, unless the switching power supply is more than double the required power. Because, when the motor work is a large inductive load, will form a momentary high voltage on the power supply side. And the switching power supply overload performance is not good, will protect the shutdown, and its precision voltage regulation performance and do not need, sometimes may cause damage to the switching power supply and driver. Can be used with conventional toroidal or R-type transformer-variable DC power supply.
