The principle of hydraulic press is made by using Pascal's law. There are many kinds of hydraulic press. Of course, the uses are varied according to the needs. For example, according to the type of liquid transmission pressure, there are two major types of oil press and hydraulic press.
1. The hydraulic pump is the prime power of the hydraulic system. The work of the hydraulic press is to make the hydraulic oil enter the cylinder / piston through the hydraulic pipeline by the driving force of the pump.
2. There are several groups of seals in the oil cylinder / piston that match each other. The sealing in place in one step is not suitable, but all of them play an important role in sealing, so that the hydraulic oil does not flow out.
3. Finally, the hydraulic oil circulates in the oil tank through the one-way valve to make the oil cylinder / piston cycle work.
The basic principle is that the oil pump delivers the hydraulic oil to the integrated cartridge valve block, and distributes the hydraulic oil to the upper chamber or lower chamber of the oil cylinder through each one-way valve and overflow valve. Under the action of high-pressure oil, the oil cylinder moves. Hydraulic press is a kind of equipment that uses liquid to transmit pressure. When liquid transfers pressure in a closed container, Pascal's law is obeyed. The hydraulic transmission system of four column hydraulic press is composed of power mechanism, control mechanism, actuator, auxiliary mechanism and working medium. The power mechanism usually uses the oil pump as the power mechanism, which is generally an integral oil pump. In order to meet the requirements of the speed of the actuator, one or more oil pumps are selected. Gear pump for low pressure (oil pressure less than 2.5MP), vane pump for medium pressure (oil pressure less than 6.3mp), plunger pump for high pressure (oil pressure less than 32.0mp). It can also be used for pressing powder products, grinding wheels, bakelite and resin thermosetting products.
When the hydraulic compressor is working, the electro-hydraulic directional valve 6 is powered on by the electric pump 3, and then enters the right position of the electro-hydraulic directional valve 6 through the sequence valve 4, and then enters the upper chamber of the upper cylinder 12 through the check valve 9, and then enters the upper chamber of the oil cylinder through the solenoid valve 7. The return oil flows back to the oil tank through the back pressure valve 13 of the one-way sequence valve and 14 of the hydraulic control valve, and returns to the oil tank through the electro-hydraulic directional valve 7; the upper cylinder of the hydraulic press operates under its own weight The oil in the make-up tank will be sucked into the upper chamber of the upper cylinder through the hydraulic control one-way valve to eliminate the vacuum and maintain the rapid downward movement of the upper cylinder.
When the upper cylinder of the oil compressor drives the upper mold and the lower mold to close, the oil continues to enter the upper cavity of the upper cylinder, the pressure of the upper chamber of the oil cylinder increases, the hydraulic control check valve at the make-up tank is closed, the oil supply of the make-up tank is cut off, the downward speed of the upper cylinder 12 starts to slow down, and the pressure of the upper chamber of the oil cylinder continues to increase. When the setting value of the pressure relay 10 is exceeded, the signal will be sent out to control the conversion of the electro-hydraulic directional valve 6 Cut off the oil supply to the upper chamber of oil cylinder 12 at the middle position, stop the movement system of the upper cylinder of the hydraulic press, and maintain the pressure for about 40s; after the completion, the left position of the hydraulic electromechanical hydraulic directional valve 6 is connected, and the pressure oil of pump 3 flows through the sequence valve 4, the left position of the electro-hydraulic directional valve 6, and the hydraulic control check valve 14 And back pressure valve 13 enter the lower chamber of upper oil cylinder 12 to push the oil cylinder to move upward. At the same time, the solenoid valve 7 is switched to the left position, and the oil tank replenishes oil to accelerate the return journey; the return oil from the upper chamber of the oil cylinder 12 of the hydraulic press flows back to the makeup tank 11 through the hydraulic control one-way valve, and the upper cylinder can quickly return to its original position.
When the middle position of the electro-hydraulic directional valve 6 is connected with the right position of the electro-hydraulic directional valve, the pressure oil pumped out by the pump 3 enters the lower chamber of the lower cylinder 16 through the left position of the Electro-hydraulic Directional Valve of the oil compressor. The return oil flows into the oil return tank from the upper chamber of the lower cylinder 16 through the left position of the electro-hydraulic directional valve, and the lower cylinder pushes out the workpiece upward. After the workpiece is taken out, the right position of the hydraulic reversing valve starts to work, and the pressure oil enters the upper chamber of the lower cylinder 16, The return oil from the lower chamber of the lower cylinder flows into the oil return tank through the right position of the valve, and the lower cylinder moves downward to return to its original position; the valve 13 can prevent the oil from flowing backward in the upper chamber of the upper cylinder 12, and the travel switch 15 is used to control the limit position of the upper and lower cylinders. At this time, the pressure gauge shows the pressure values of the upper and lower cylinders of the hydraulic press and the whole system.
