Manifold block

How to deal with abnormal movement of Manifold block hydraulic system actuator?

How to deal with abnormal movement of Manifold block hydraulic system actuator?

 

The frequent failure phenomenon of the hydraulic system actuator is: the normal system pressure actuator has no action, the actuator moves too slowly, and the mechanism crawls. These types of faults are closely related to abnormal traffic. Therefore, when the hydraulic actuator can not work normally, the fault can often be found by the flow of this working parameter and be eliminated.

 

Performance one, the system pressure normal implementation element no action

 

Fault reason 1. Hydraulic cylinder structure reason

 

A. The end face of the piston and the end face of the cylinder are close together, the working area is insufficient, so it can not start;

 

Elimination method: to add an oil groove on the end face, so that the working liquid quickly flow to the end face of the piston.

 

B. The one-way valve on the cylinder with a buffer device is blocked by the piston;

 

Elimination method: the position of oil inlet and outlet of cylinder should be staggered with the end face of piston.

 

2. The piston rod moves “don’t be strong”

 

A. The clearance between cylinder and piston, guide sleeve and piston rod is too small;

 

Elimination method: check the fit clearance, and match to the specified value.

 

B. The fit between the piston rod and the laminated bakelite guide sleeve is too small;

 

Elimination method: check the fit clearance, repair the guide sleeve hole, meet the requirements of the fit clearance.

 

C. Poor assembly of hydraulic cylinder (such as poor coaxiality between piston rod, piston and cylinder head, and poor parallelism between hydraulic cylinder and workbench);

 

Elimination method: reassembly and installation, unqualified parts should be replaced.

 

Fault cause 3. Cause caused by hydraulic circuit

 

The main reason is that the oil in the back pressure chamber of the hydraulic cylinder is not communicated with the oil tank, and the throttle port of the speed control valve on the oil return road is regulated too small or the directional valve connected with the oil return is not moved;

 

Elimination method: Check the cause and eliminate.

 

Performance two, the executive component action is too slow

 

Cause 1. The internal leakage is serious

 

A. Seals are seriously damaged;

 

Elimination method: replace the seal.

 

B. The viscosity of oil is too low;

 

Elimination method: replace hydraulic oil with suitable viscosity.

 

C. The oil temperature is too high;

 

Elimination method: Check the cause and eliminate.

 

Cause 2. The external load is too large

 

A. Design error, selection pressure is too low;

 

Elimination method: replace components after accounting, adjust the working pressure.

 

B. Process and use errors, resulting in the external load is greater than the predetermined value;

 

Elimination method: use according to the specified value of equipment.

 

Fault reason 3. “don’t be strong” when the piston moves

 

1. Machining accuracy is poor, the taper and roundness of cylinder hole are out of tolerance

 

A. Piston rod and piston are not coaxial

 

Elimination method: correction of both coaxiality

 

B. Full length or local bending of the piston rod

 

Elimination method: alignment of piston rod

 

C. Poor straightness of inner hole of hydraulic cylinder (drum taper, etc.)

 

Elimination method: boring and grinding repair, rematch the piston

 

D. Corrosion and hair pulling in the cylinder

 

Elimination method: slight repair rust and burr, serious must boring and grinding

 

2. Poor assembly quality

 

A. Coaxiality difference between piston, piston rod and cylinder head;

 

Elimination method: reassemble as required.

 

B. Parallelism difference between hydraulic cylinder and workbench;

 

Elimination method: reassemble as required.

 

C. The clearance between the piston rod and the guide sleeve is too small;

 

Elimination method: check the fit clearance, repair the guide sleeve hole, meet the requirements of the fit clearance.

 

3. The sealing ring of the end cover of the hydraulic cylinder is pressed too tight or too loose

 

Elimination method: adjust the sealing ring, so that it is not tight or loose, to ensure that the piston rod can be pulled back and forth by hand smoothly without leakage.

 

4. The nuts at both ends of the double piston rod are screwed too tight, so that its coaxiality is bad

 

Elimination method: the nut is not easy to screw too tight, generally by hand can be tightened, to keep the piston rod in a natural state.

 

Fault reason 4. Dirt enters the sliding part

 

A. The oil is dirty;

 

Elimination method: filter or replace the oil.

 

B. The dust ring is damaged;

 

Elimination method: replace the dust ring.

 

C. The assembly is not cleaned or dirt is brought in;

 

Elimination method: open cleaning, assembly should pay attention to cleaning.

 

Cause of failure 5. The speed of the piston at the end of the stroke drops sharply

 

A. The buffer regulating valve orifice adjustment is too small, in the buffer stroke, the piston may stop or speed sharply decreased;

 

Elimination method: the opening of the buffer throttle valve should be adjusted appropriately, and can play a buffering role.

 

B. The diameter of the orifice in the fixed buffer device is too small;

 

Elimination method: appropriately increase the throttle diameter.

 

C. The gap between the fixed buffer throttling ring and the buffer plunger on the cylinder head is too small;

 

Elimination method: appropriately increase the gap.

 

Performance three, the organization crawl

 

Hydraulic cylinder movement speed in 5mm/s below, should try to prevent crawling phenomenon.

 

1. The new hydraulic cylinder, the repaired hydraulic cylinder or the hydraulic cylinder whose downtime is too long, the air in the cylinder or the exhaust in the hydraulic cylinder pipeline is not drained;

 

Elimination method: no load large stroke reciprocating motion, until the air exhaust.

 

2. Negative pressure is formed inside the cylinder, and air is inhaled from the outside;

 

Elimination method: first seal the joint surface and joint with grease, if the suction situation is better, tighten the fastening screw and joint.

 

3. The volume of the pipeline from the cylinder to the reversing valve is much larger than the content of the hydraulic cylinder. When the hydraulic cylinder is working, the oil in this section of the pipeline is not exhausted, so it is difficult to drain the air.

 

Elimination method: the exhaust valve can be added at the top of the pipeline near the hydraulic cylinder, and the valve can be unscrewed. The piston rod moves for many times under the condition of full stroke, and then the exhaust valve is closed after the air is exhausted.

 

Fault cause 4. Pump suction air

 

A. A certain amount of air dissolved in the oil, and bubbles are generated in the process of work;

 

Elimination method: add a separator in the oil tank, and then inhale the return oil after defoaming through the separator, and the defoaming agent in the oil.

 

B. The oil return eddy current strongly generates foam;

 

Elimination method: the suction pipe and the return pipe should be separated from a certain distance, the return pipe mouth should be inserted below the oil level.

 

C. There is air in the pipe or the pump housing memory;

 

Elimination method: no-load operation, air exclusion.

 

D. The depth of the suction pipe immersed in the oil surface is not enough;

 

Elimination method: lengthen the suction pipe, fill oil into the tank to raise the liquid level.

 

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Manifold Block hydraulic system common faults and troubleshooting – hydraulic system noise, vibration, how to do