MarketsHydraulic systems in the power and coal industries

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Electricity and coal are important parts of the energy industry. The mechanical equipment used in the modern coal industry includes mining machinery, coal cutting machinery, washing machinery, transportation and secondary processing machinery, etc. The application of hydraulic technology in modern coal machinery and equipment is becoming more and more extensive. In addition to the well-known hydraulic drive coal face comprehensive mechanized complete set of equipment, hydraulic technology is used in mine drawworks brakes, computerized electro-hydraulic control and performance testing of supporting equipment, and ground coal It has also been used in equipment such as loading and unloading production lines and raw coal sampling machines.

The working principle of the entire hydraulic system is as follows:


    After the steel pipe of a predetermined length is fed into the elbow mold, the electromagnet 15YA is energized to switch the reversing valve 21 to the left position, and the quantitative pump 19 increases the pressure (the pressure is set by the valve 18). The solenoid 7YA is energized, the reversing valve in the oil circuit 6 is switched to the left position, and the pressure oil of the pump 19 enters the upsetting clamping cylinder through the check valves 15, 17 and the pressure reducing valve and the throttle valve in the oil circuit 6} The rodless cavity is connected to the hydraulic control check valve in the oil circuit 6 to clamp the steel pipe, and the cylinder 1 has a rod cavity through the left check valve, hydraulic control check valve and cooler in the oil circuit 6. 24 and the filter 27 drain oil to the oil tank. After the steel pipe is clamped, the pressure relay 2YJ in the oil circuit 6 sends a signal, the compression wheel and the measuring wheel are reset, the solenoid 9YA is energized, the reversing valve in the oil circuit 7 is switched to the left position, and the pressure oil of the pump 19 is unidirectional Valves 15, 17 and the pressure reducing valve, throttle valve, and left hydraulic control check valve in the oil circuit 7 enter the rod cavity of the tightening cylinder 2 and conduct the right hydraulic control check valve, and the cylinder 2 drives and starts. The elbow mold makes it at the center of the steel pipe bending. Then, the solenoid 9YA is de-energized, 11YA is energized, the directional valve in the oil circuit 8 is switched to the left position, and the pressure oil of the pump 19 enters through the check valves 15, 17 and the pressure reducing valve and throttle valve in the oil circuit 8. The rodless cavity of the hydraulic cylinder 3 of the upper and lower pipe bending molds is connected with a hydraulically controlled one-way valve. The cylinder 3 drives the upper and lower pipe bending molds to be in place and close successively, and the clamp blocks on the pipe bending mold clamp the steel pipe. Then, the electromagnet 9YA is energized again, the tightening cylinder 2 is tightened and locked, and the steel pipe is always tightly attached to the pipe bending die through the chute. At this point, the hydraulic auxiliary part has completed the clamping action on the steel pipe, waiting for the pipe bend.


    Before the pipe is bent, the electromagnet 16YA is energized, the system pressure rises to the constant pressure value set by the constant pressure variable pump 20 (set by the pilot relief valve 22), the remote control sequence valve 14 is opened, and the pump 19 is unloaded through the valve 14. The clamping force of each clamping cylinder to the steel pipe is guaranteed by the pressure oil of the constant pressure variable pump 20, and the pump 20 supplies oil to the hydraulic servo circuit. Under the control of the servo loop, the pipe bending cylinder 5 drives the pipe bending die to rotate the pipe, and the upsetting cylinder 4 pushes the upsetting clamping cylinder 1 to apply axial thrust to the steel pipe. The two coordinate and cooperate to complete the task of bending the steel pipe. (The position servo control principle of the two cylinders is shown in the block diagram 3-2). At the same time, the pneumatic oil injection pump continuously injects a certain amount of lubricant into the elbow mold to prevent wrinkle lubrication of the steel pipe. After bending, in order to avoid scratching the pipe wall when opening the mold, let the bending mold rebound slightly.

(图1)


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