We want to understand the cylinder seals matters

(1) Size of cylinder seals

When the seal is not installed, there are four sizes, which can be seen by everyone and measured with a measuring tool. The four dimensions are: the inner diameter of the seal root, the outer diameter of the root, the inner diameter of the lip and the outer diameter of the lip.

(2) The size of the seal device into the groove

When the seal device is not working in the groove, the groove size remains unchanged, and the size of the seal has all changed, the four dimensions are: the outer diameter of the seal root and the outer lip diameter change to the groove outer diameter at the same time; The diameter of the inner lip is the diameter of the piston rod, and the inner diameter of the root is the gap between the seal and the piston rod plus the diameter of the piston rod.

(3) When the cylinder starts working, the state of the seal

When the cylinder starts to work, the working state of the cylinder seals is: the inner and outer lips are close to the inside, and the outer wall is slightly moved backward. The root of the seal is squeezed backwards, and as the pressure increases, the hydraulic oil exerts greater force on the seal, and the overall deformation of the seal increases. When the working cycle is completed and the cylinder is under no pressure, the seal is restored to its original state. Repeat deformation, repeat recovery, until the effective volume of the seal lips is lost, the seal is damaged.

Cylinder groove size tolerance and seal fit

(1) cylinder seals are commonly used in reciprocating cylinders of hydraulic systems.
The pressure surface of the seal has a lip shape, and there is a small amount of interference in the device, so that the lip edge and the sealing surface are in full contact and have a sealing effect. When the cylinder is working, the contact force and contact area increase with the increase of pressure, and the sealing performance improves with the increase of pressure. When the cylinder returns, the pressure decreases, the contact area and contact force decrease, and the sealing performance decreases accordingly. This lip operation process is similar to the human breathing process. In addition, this process also acts as a smooth lip.

(2) The production of seals in all countries in the world has strict requirements on the tolerance and roughness of the groove size. Therefore, cylinder production must be produced strictly according to tolerance and roughness requirements.

cylinder seals are prone to appear

Condition one. If the trench is too deep, two conditions will arise:

A. The gap between the seal root and the groove becomes larger, which will cause the seal root to be unfixed.

B. The interference quality of the seal lip and sealing surface becomes smaller, and the rebound force of the seal becomes smaller, so the fault rate of low-pressure oil leakage will increase when the piston rod beats.

Condition two, the groove is too shallow, will also produce two conditions:

A, resulting in the sealing oil lip and sealing surface of the interference increased, the contact area increased, resulting in greater friction, in the cylinder return trip seal lip can not be effectively lubricated, increase in heat, accelerate the damage to the seal lip.

B, resulting in a smaller clearance of the seal root, resulting in an increased chance of the seal root being squeezed out when the cylinder is under high pressure.

Condition three, the roughness of the cylinder

If the roughness of the hydraulic cylinder exceeds the requirements, it will also lead to two conditions:

A. It will lead to increased friction between the inner and outer lips of the seals, and speed up the damage of the lips.

B. The amount of oil in each contact surface area of the seal and the cylinder increases, and the possibility of oil seepage increases.