Created on:2021-06-25 09:07

Fault diagnosis and maintenance of common hydraulic plate bending press

Fault diagnosis and maintenance of common hydraulic plate bending press

Wb67y160t ordinary hydraulic plate bending press is widely used. The hydraulic schematic diagram is shown in Fig. L. the fault analysis and troubleshooting methods are as follows.

L.jpg

(1) The slider doesn't move, but it can go down by its own weight

Axial piston pump can not supply pressure oil: a. the oil tank is short of oil; b. If the motor fails to start, check and repair the start button, AC contactor, thermal relay and motor; c. If the plunger pump itself fails, disassemble and inspect or replace the plunger pump.

② The main oil overflow valve may be blocked, improperly adjusted, spring broken or valve core rusted and stuck. The relief valve needs to be adjusted, repaired or replaced.

(2) The slider is not parallel

① There is air in the balance cylinder. Tighten the hand wheel of the air release valve 7 for air release and oil filling. After removing the air, loosen the air release valve.

② The vent valve 7 has leakage. Remove and check the seal of the vent valve cone, repair or replace the vent valve.

③ Check valve 10 has internal leakage. Disassemble and check the sealing surface of check valve cone. Grind the sealing surface of cone. Line contact is better or replace the check valve.

④ Check the looseness of the inclined iron fastening screw at the head of the piston rod of the balance cylinder and tighten the inclined iron fastening screw at the head of the piston rod.

(3) The slider can't go down

① Electromagnetic directional valve 4 can't change direction. A. ct4a doesn't work. Check the circuit, repair or replace ct4a; b. Ct4a shell fixed screw loose, check and tighten; c. The spool of directional valve is stuck. Clean, grind or replace the spool.

② One way throttle valve 9 spool stuck or closed, maintenance and cleaning.

(4) The slider only goes down but not up

① The solenoid directional valve 4 can not change direction. A. the valve core is stuck. Clean and grind or replace the slide valve; b. If the ct4b does not work or the housing fixing screw is loose, check the circuit, repair or replace the ct4b and tighten the housing fixing screw.

② The hydraulic control check valve 14 cannot be opened, and the valve core is stuck. Repair, clean or replace it.

③ The fault of pressure relay may be that the spring is loose. Turn the hand wheel of pressure relay clockwise to compress the spring.

④ The sealing ring of piston cylinder 13 is seriously worn. Replace the sealing ring.

(5) The return speed of the slider is slow and the pressure is high

① The fault of solenoid directional valve 4 may be that the fixing screw of ct4b shell is loose or the valve core push rod is worn. Tighten the fixing screw of ct4b shell, clean and repair the valve core push rod or replace the slide valve.

② The hydraulic control check valve 14 is faulty, the valve core is stuck, and the oil return is not smooth. Repair, clean or replace the hydraulic control check valve.

(6) Slide down slow

① If the oil filling pressure is too high, tighten the air release handwheel and readjust the oil filling pressure.

② The throttle valve of one-way throttle valve 9 is not adjusted properly or the valve core is stuck for maintenance and cleaning, and the opening amount of throttle valve is readjusted.

(7) When the slider reaches the bottom dead center, it will move

① The charging pressure is too low. Check and adjust the charging pressure.

② The inclined iron fastening screw at the piston rod head of synchronous cylinder is loose, and the inclined iron fastening screw is tightened.

(8) When the system pressure drops to the reset value regulated by the pressure relay, the slider cannot return automatically

① Pressure relay 8 failed to send signal due to its own or control circuit fault, ct4b failed to power on or damaged, solenoid directional valve 4 spool stuck and could not change direction. Check and eliminate one by one.

② Ct15 and ct16 fail to power off or the valve core is stuck. Check and repair the control circuit, clean, grind or replace the slide valve.

(9) There is no main pressure in the system

① The overflow valve 3 is in trouble, the damping hole is blocked, the adjustment is improper, the spring is broken, the cone surface of the valve core is not well sealed or the valve core is stuck. Clean, grind, adjust, repair or replace the overflow valve.

② The solenoid directional valve 15 is faulty and the valve core is stuck. Clean, grind or replace the slide valve.

(10) Remote voltage regulation does not work

① Electromagnetic directional valve 16 can not change direction, ct16 can not act, valve core is stuck or ct16 electromagnet shell fixed screw is loose, check the circuit, repair or replace ct16, clean, grind or replace slide valve, tighten electromagnet shell fixed screw.

② The remote pressure regulating relief valve 5 is faulty, the damping hole is blocked, the spring is broken, the valve core is stuck, or the cone surface is not well sealed. Clean, grind, replace the spring or replace the relief valve.

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