The reversing process of the cylinder of the servo hydraulic machine:
The reversing process is as follows: When the hydraulic cylinder is reversing, the pilot valve spool is first moved by the control of the stopper. After the pilot valve is reversed, the hydraulic reversing valve controlled by the servo hydraulic machine operates the hydraulic reversing valve to control the oil path. The oil path is the same as the aforementioned flow path. The oil return path changes the direction of the oil path three times successively, so that the spool of the reversing valve sequentially produces the first quick jump one + slow movement → the second quick jump.
In this way, the reversing process of the hydraulic cylinder has experienced three stages: rapid braking, stopping, and rapid reverse start. The specific process is as follows.
When the right to left stop of the worktable hits the pilot valve lever to move the spool to the left, the right brake cone a2 on it gradually closes the oil return passage of the hydraulic cylinder, and the hydraulic cylinder gradually decelerates to achieve prefabrication move. When the pilot valve spool moves, its right ring groove connects control oil circuits 4 and 6, and its left ring groove connects oil circuit 5 to the tank, the control oil circuit is switched, and the flow of the control oil circuit at this time The route is as follows.
The hydraulic machine inlet oil line z hydraulic pump → fine filter → oil line 1 → oil line 4 one + pilot valve one is called by way 6 → one-way valve I → reversing valve right cavity. Depending on the position of the spool, there are three oil passages for the return parking from the left cavity of the reversing valve to the fuel tank. The first oil circuit is the oil return route at the stage when the spool starts to move. The left cavity of the reversing valve is a route 8-, oil circuit 5→pilot valve→oil tank. There is no throttling element in the oil return path, and the oil path is unobstructed, so the spool moves at a high speed, resulting in the first rapid jump.
The first quick jump causes the middle shoulder of the valve core to move to the undercut groove of the valve sleeve, causing the oil passages of the two chambers of the hydraulic cylinder to communicate and the workbench to stop moving. When the cylindrical part of the left end of the reversing valve spool covers the oil passage 8 in the Hydraulic Press, the first quick jump ends. After that, the return parking of the left cavity can only pass through the throttle valve J1 to the oil circuit 5 and return to the fuel tank. In this way, the spool moves slowly at the speed set by the throttle valve J1.
During this period, the two chambers of the hydraulic cylinder continue to communicate with each other, and the workbench is stopped for a period of time. This is the end stop before the worktable is reversed. The dwell time of the hydraulic press is set by the throttle valve J1, and the adjustment range is 0~5s.
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