The hydraulic system of a bending machine plays a crucial role in its operation, providing the force necessary to bend metal sheets accurately and efficiently. Understanding the working principle of the hydraulic system can shed light on how these machines function.
Hydraulic System Components
Hydraulic Pump: The hydraulic pump is responsible for generating hydraulic pressure by converting mechanical energy into fluid energy. It draws hydraulic fluid from the reservoir and delivers it to the hydraulic system at high pressure.
Hydraulic Fluid: Typically, oil is used as the hydraulic fluid in bending machines due to its excellent lubricating properties and ability to withstand high pressures. The hydraulic fluid transfers energy within the system and ensures smooth operation.
Control Valves: Control valves regulate the flow and direction of hydraulic fluid within the system. They open and close in response to signals from the operator or control system, controlling the movement of hydraulic cylinders and other actuators.
Hydraulic Cylinders: Hydraulic cylinders are the primary actuators responsible for exerting force on the bending machine’s ram or beam. They convert hydraulic pressure into linear motion, pushing or pulling the bending tool to bend the metal sheet.
Pressure Relief Valve: The pressure relief valve is a safety device that limits the maximum pressure in the hydraulic system. It prevents overloading and damage to the components by diverting excess fluid back to the reservoir when the pressure exceeds a predetermined level.
Working Principle of Bending Machine Hydraulic System
Start
All the electromagnets are not energized, and the main pump output oil is unloaded through the valve 6 and the valve 21 in the neutral position.
Master cylinder quickly descends
The electromagnets 1Y, 5Y is energized, the valve 6 is in the right position, and the control oil is opened through the valve 8 to make the pilot operated check valve 9 open.
Inlet path: pump 1- valve 6 right position – valve 13 – upper cylinder upper chamber.
Return line: main cylinder lower chamber – valve 9 – valve 6 right position – valve 21 neutral – fuel tank.
The master cylinder slide descends rapidly under the action of its weight. Although the pump 1 is in the maximum flow state, it still cannot meet its needs. Therefore, the upper chamber of the master cylinder forms a negative pressure, and the oil of the upper tank 15 enters the upper chamber of the master cylinder through the filling valve 14.
The master cylinder is approaching the workpiece at a slow speed and pressurizing
When the master cylinder slider is lowered to a certain position to touch the stroke switch 2S, 5Y loses power, the valve 9 is closed, and the oil in the lower cylinder of the master cylinder passes through the back pressure valve 10, the right position of the valve 6, and the position of the valve 21 to the oil tank.
At this time, the upper chamber pressure of the master cylinder rises, the valve 14 is closed, and the master cylinder slowly approaches the workpiece under the action of the pressure oil supplied from the pump 1. After contacting the workpiece, the resistance increases sharply, the pressure is further increased, and the output flow of the pump 1 is automatically reduced.
Holding pressure
When the upper chamber pressure of the master cylinder reaches a predetermined value, the pressure relay 7 sends a signal to deactivate the Y1, the valve 6 returns to the neutral position, the upper and lower chambers of the master cylinder are closed, and the tapered surfaces of the check valve 13 and the liquid filling valve 14 ensure a good seal. Sex, keep the master cylinder under pressure.
The holding time is adjusted by the time relay. During the holding pressure, the pump is unloaded through the center of valve 6.21.
Pressure relief
The main cylinder return stroke is over, the time relay sends a signal, 2Y is energized, and valve 6 is in the left position.
Since the pressure in the upper chamber of the master cylinder is high, the pressure slide valve 12 is in the upper position, the pressure oil causes the external control sequence valve 11 to be opened, and the pump 1 outputs the oil to return to the oil tank through the valve 11. The pump 1 is operated at low pressure, and the pressure is insufficient to open the main spool of the filling valve 14, but the unloading spool of the valve is first opened, so that the oil in the upper cylinder of the master cylinder is vented back to the upper tank through the opening of the unloading spool. The pressure gradually decreases.
When the pressure in the upper cylinder of the master cylinder leaks to a certain value, the valve 12 returns to the lower position, the valve 11 is closed, the pressure of the pump 1 is raised, the valve 14 is fully opened, and the oil inlet path is at this time: the pump 1 – the valve 6 left position – the valve 9 – the main Under the cylinder. Return oil circuit: master cylinder upper chamber – valve 14 – upper fuel tank 13. Realize the master cylinder quick return.
Master cylinder stop in situ
When the master cylinder slider rises to the touch stroke switch 1S, 2Y loses power, the valve 6 is in the neutral position, the hydraulic check valve 9 closes the lower chamber of the master cylinder, and the master cylinder stops in place. The pump 1 output oil is unloaded through the valve 6 valve 21 in the neutral position.
Lower cylinder ejector and return
3Y is energized and valve 21 is in the left position.
Intake circuit: pump 1 – valve 6 neutral – valve 21 left position – lower cylinder lower chamber.
Return line: upper cylinder upper chamber – valve 21 left position – fuel tank. The lower piston rises and ejects.
3Y loses power, 4Y gets electricity, valve 21 is in the right position, and the lower cylinder piston goes down and returns.
Floating flange
After the lower piston first rises to a certain position, the valve 21 is in the neutral position, and the lower cylinder piston is forced to descend when the main cylinder slide is depressed, and the lower cylinder oil is returned to the oil tank through the throttle 19 and the backpressure valve 20, The lower pressure of the lower cylinder is maintained to maintain the required blanking pressure. The valve 20 can be adjusted to change the pressure of the floating pressure. The upper chamber of the lower cylinder is replenished from the mailbox through the center of the valve 21. The relief valve 18 is the lower cylinder safety valve.
Conclusion
In summary, the hydraulic system of a bending machine operates on the principle of converting mechanical energy into hydraulic pressure, which is then used to actuate hydraulic cylinders and bend metal sheets with precision and control. This system enables efficient and reliable bending operations in various metal fabrication applications.
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