Time:2023-04-14 09:09:10 Browse: 120
The hydraulic pump of the four-column hydraulic press is a quantitative pump, and the reversing valve is a two-position four-way electromagnetic reversing valve, which saves the valve on the oil return path of the hydraulic cylinder, so this system is a oil return speed control system. When the hydraulic cylinder returns, the hydraulic oil enters the rod cavity of the hydraulic cylinder from the one-way valve. The security valve acts as a constant pressure and overflow in the system. The failure phenomenon of hydraulic press system is that the hydraulic cylinder speed is slow and there is no large return speed.
After checking and debugging the system, it was found that the hydraulic cylinder was fast forward and the operation was normal. This is not normal when the return journey is fast. Check whether the check valve operates normally. When the hydraulic cylinder returns, there is no working load, and the system pressure is relatively low at this time. The outlet flow of the hydraulic pump of the four-column hydraulic press is input into the hydraulic cylinder through the rod cavity, so the hydraulic cylinder should have a higher rotating speed. However, it is found that the return speed of hydraulic cylinder is not only slow, but also the system pressure is still very high at present.
Disassembling and assembling the reversing valve, it is found that the reversing valve not only lacks elasticity, but also has tilt phenomenon, which makes the valve core of the reversing valve unable to return to its original position after cutting off the power supply. Therefore, the opening of the slide valve is too small to pass. The oil of the reversing valve is saved. Most of the pressure oil output by the hydraulic pump is returned to the oil tank through the overflow valve. At this time, switch the pressure in front of the valve to the set pressure of the security valve, which is the reason why the pressure rises during the return of the hydraulic cylinder.
The increase of return resistance of the valve core may also be caused by dust entering the clearance of the slide valve, which then makes the movement of the valve core difficult. The gap between the valve core and the valve hole is too small, causing the valve to expand and get stuck when the oil temperature rises. The resistance of the seal of the electromagnetic push rod is too large, and the valve hole is deformed when the solenoid valve is installed. As long as you can find the real cause of the paper jam, the corresponding cleaning method will be easy.
Because most pressure oil overflows into the fuel tank, there is less oil in the Rod cavity through the reversing valve of the four-column hydraulic press. Therefore, the return stroke of the hydraulic cylinder does not have a large speed.
The solution to the failure of this type of four-column hydraulic press is that the slide valve cannot return to the original position, which is the reason for the spring and the qualified spring should be replaced. If sliding is caused by poor precision and radial clamping occurs, the valve core should be repaired or manufactured from scratch. The tolerance of common valve core bitter taper is 0.003-0.005. It is better to make the valve core have a small taper, and its big end is on the side of the low-pressure chamber, which can automatically reduce problems, reduce friction, and then reduce or avoid warping clamping force.
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