What are the details to pay attention to when detecting and maintaining REXRPTH cylinders
The REXRPTH cylinder barrel and cylinder head, piston and piston rod, sealing device, buffering device, and exhaust device constitute a non-standard cylinder. As the main component of oil cylinders, mining single supports, hydraulic supports, cannon barrels and other products, the machining quality of non-standard oil cylinders directly affects the service life and performance of the entire product. The processing requirements for cylinder barrel are high, and its inner surface roughness requires strict requirements for coaxiality and wear resistance. The basic characteristic of cylinder barrel is deep hole machining, which has always troubled the workers. Using rolling processing, due to the residual compressive stress left on the surface layer, it helps to close small cracks on the surface and hinders the propagation of erosion.
The REXRPTH cylinder is an actuator that converts hydraulic energy into mechanical energy in a hydraulic system. The faults can be basically summarized as non-standard hydraulic cylinder misoperation, inability to push the load, and piston slip or crawling. It is not uncommon for non-standard oil cylinders to shut down due to malfunctions, as fault diagnosis and maintenance of non-standard oil cylinders are crucial.
The main methods for checking and maintaining non-standard oil cylinders in REXRPTH are as follows. We hope it can be helpful for everyone's operation. More information about non-standard oil cylinders will continue to be organized for everyone. Please stay tuned.
(3) The hydraulic system control pressure is too low. The throttling resistance in the control pipeline may be too high, the flow valve may be improperly adjusted, the control pressure may be inappropriate, and the pressure source may be disturbed. At this point, the control pressure source should be checked and the pressure adjusted to the specified value of the system.
(4) Air enters the hydraulic system. Mainly due to leaks occurring in the system. At this time, it is necessary to check the liquid level of the hydraulic oil tank, the sealing components and pipe joints on the suction side of the hydraulic pump, and whether the suction coarse filter is too dirty. If so, hydraulic oil should be replenished, seals and pipe joints should be treated, and the coarse filter element should be cleaned or replaced.
(5) The initial movement of the hydraulic cylinder is slow. At low temperatures, hydraulic oil has high viscosity and poor fluidity, resulting in slow hydraulic cylinder movement. The improvement method is to replace the hydraulic oil with better viscosity and temperature performance. At low temperatures, a heater or the machine itself can be used to heat up the oil temperature during startup. The normal operating oil temperature of the system should be maintained at around 40 ℃.
2. Cannot drive load during operation
The main manifestations include inaccurate piston rod positioning, insufficient thrust, decreased speed, unstable operation, etc. The reasons are:
(1) Internal leakage of hydraulic cylinder. Internal leakage of hydraulic cylinders includes leakage caused by excessive wear of the hydraulic cylinder body seal, piston rod and seal cover seal, and piston seal.
The reason for the leakage of the piston rod and sealing cover seal is due to the wrinkling, squeezing, tearing, wear, aging, deterioration, deformation, etc. of the seal. At this time, a new seal should be replaced.
The main reasons for excessive wear of piston seals are improper adjustment of the speed control valve, resulting in excessive back pressure and improper installation of seals or hydraulic oil contamination. Secondly, there are foreign objects entering during assembly and poor quality of sealing materials. The consequence is slow and powerless movement, and in severe cases, it can also cause damage to the piston and cylinder, resulting in the phenomenon of "pulling the cylinder". The solution is to adjust the speed control valve and make necessary operations and improvements according to the installation instructions.
(2) REXRPTH cylinder circuit leakage. Including leaks in valves and hydraulic pipelines. The maintenance method is to operate the directional valve to check and eliminate leaks in the hydraulic connection pipeline.
(3) REXRPTH oil cylinder bypass return tank. If the overflow valve gets stuck in the valve core due to dirt, causing the overflow valve to remain open, hydraulic oil will bypass the overflow valve and flow directly back to the oil tank, resulting in no oil entering the hydraulic cylinder. If the load is too large, although the regulating pressure of the relief valve has reached the maximum fixed value, the hydraulic cylinder still cannot obtain the thrust required for continuous operation and does not move. If the adjustment pressure is low, it will not reach the required vertebral force due to insufficient pressure, resulting in insufficient thrust. At this time, the overflow valve should be checked and adjusted.
3. Piston slippage or crawling
The sliding or crawling of the REXRPTH cylinder piston will cause unstable operation of the hydraulic cylinder. The main reasons are as follows:
(1) The REXRPTH cylinder has internal stagnation. Improper assembly, deformation, wear, or tolerance limitations of internal components in hydraulic cylinders, coupled with excessive resistance to movement, can cause the piston speed of the hydraulic cylinder to change with different stroke positions, resulting in slippage or crawling. Most of the reasons are due to poor assembly quality of the parts, surface scratches or iron filings generated by sintering, which increase resistance and decrease speed. For example, the piston and piston rod are not concentric or the piston rod is bent, the hydraulic cylinder or piston rod is offset from the guide rail installation position, and the sealing ring is installed too tightly or too loosely. The solution is to repair or adjust again, replace damaged parts and iron filings.
(2) Poor lubrication or poor machining of hydraulic cylinder aperture. Due to the relative motion between the piston and cylinder barrel, guide rail and piston rod, poor lubrication or poor hydraulic cylinder aperture can exacerbate wear and reduce the straightness of the cylinder barrel line. In this way, when the piston works inside the hydraulic cylinder, the frictional resistance will vary, resulting in slippage or crawling. The elimination method is to first grind the hydraulic cylinder, then prepare the piston according to the matching requirements, grind the piston rod, and configure the guide sleeve.
(3) REXRPTH cylinder or hydraulic cylinder enters the air. Air compression or expansion can cause piston slippage or crawling. The elimination measure is to check the hydraulic pump, set up a specialized exhaust device, and quickly operate the full stroke back and forth several times to exhaust.
(4) The quality of seals is directly related to slippage or crawling. When used under low pressure, O-ring seals are more prone to sliding or crawling compared to U-shaped seals due to their higher surface pressure and greater difference in dynamic and static friction resistance; The surface pressure of the U-shaped sealing ring increases with the increase of pressure. Although the sealing effect also improves accordingly, the difference in dynamic and static friction resistance also increases, and the internal pressure increases, affecting the elasticity of the rubber. Due to the increased contact resistance of the lip, the sealing ring will tilt and the lip will elongate, which is also prone to sliding or crawling. To prevent it from tilting, a supporting ring can be used to maintain its stability.