Transmission structure of single column hydraulic press
single column hydraulic presstransmission structure
When the drive shaft continues to rotate, its vector diameter decreases, and the working plunger extends outward under the action of the return spring, so that the volume of the sealed working chamber becomes larger and a vacuum is formed. The hydraulic oil in the oil tank pushes the suction valve open. Enter the working chamber under the action of atmospheric pressure. When the eccentric drive shaft rotates to the point, the oil suction is completed. The eccentric drive shaft rotates once, and the pump sucks and discharges oil once.
It can be seen that the hydraulic pump can absorb and discharge oil according to the volume change of the sealing working chamber. Therefore, the hydraulic pump is called a positive displacement pump. The single plunger pump has only one working chamber, the output liquid has poor continuity and large pulsation, and can only be used for very simple liquid delivery equipment or operating equipment.
As the energy component of the hydraulic transmission and control system, the hydraulic pump of the press needs to meet the following conditions to meet the requirements:
(1) In terms of structure, several sealed working chambers with variable volume are required.
All studios can be changed from small to large, from large to small, smooth and continuous change.
Oil absorption and oil discharge need to be strictly separated, that is, there needs to be an oil distribution mechanism.
single column hydraulic pressWith the characteristics of the overflow valve
Pressure control valve-relief valve is a key indicator to measure the operating performance of single column hydraulic press. It plays a role of constant pressure overflow, pressure stabilization, system unloading and safety protection in hydraulic equipment. The core indicators include static and dynamic performance indicators, such as the stroke of the unloading pump and the return chamber of the back pressure hydraulic cylinder.
single column hydraulic pressThe principle of using the overflow valve and the specific effect of the five core indicators:
single column hydraulic press: Relief valve principle
In the metering pump throttle control system, the metering pump provides a constant flow rate, and when the system pressure increases, the flow demand will decrease. At this time, the overflow valve is opened to overflow the excess flow back to the tank to ensure the inlet pressure of the overflow valve.
In the metering pump throttle control system, the metering pump provides a constant flow. As the system pressure increases, the flow demand will decrease. At this time, the overflow valve is opened to overflow the excess flow back to the tank to ensure that the inlet pressure of the overflow valve, that is, the pump outlet pressure is constant.
single column hydraulic pressFunction of overflow valve;
1. Pressure regulating overflow
When the system adopts the throttling speed regulation of the fixed pump oil supply, a throttle valve or a speed control valve is often set on the oil inlet or return road to make part of the pump oil enter the hydraulic cylinder to work, and the excess oil flows back through the overflow valve The oil tank is in the normally open state of its set pressure, and the preload of the spring is adjusted to adjust the working pressure of the system. Therefore, in this case, the function of the overflow valve is to adjust the pressure of the overflow valve
2. Safety protection
When the system uses a variable pump to supply oil, there is no excess oil overflow in the system, and its working pressure is determined by the load. At this time, the overflow valve with pump in parallel only needs to be opened in the case of overload to ensure the safety of the system. Therefore, the overflow valve in this system is also called safety valve.
3. Unloading pump When the external control port of the valve is connected to the fuel tank, when the inlet pressure is very low, the main valve core can be quickly lifted, thereby unloading the pump and reducing energy loss. When the solenoid is energized, the external control port of the overflow valve opens to the tank, thereby unloading the pump.
4. Remote voltage regulation
When the external control of the pilot relief valve is connected to the relief valve with lower pressure adjustment, as long as the oil pressure in the upper cavity of the main spool reaches the adjustment pressure of the low pressure valve, the main spool will rise and overflow, so as to realize remote pressure adjustment. When the solenoid valve works in the correct position without power supply, the external control port of the pilot relief valve is disconnected from the low pressure regulating valve, which is equivalent to blocking the external control port, and then the pilot valve on the main valve Adjust the pressure. Two-stage pressure regulation can be achieved by solenoid valve, but the set pressure of the remote pressure regulating valve needs to be lower than the set pressure of the pilot valve
5. Establish back pressure
An overflow valve is set on the oil return path of the hydraulic cylinder to generate back pressure in the stroke of the oil return cavity, thereby eliminating the forward thrust phenomenon of the hydraulic cylinder when the load suddenly decreases or becomes zero, and improving the stability of the moving parts. Therefore, the valve used for this purpose is also called a back pressure valve.