Reasons and elimination methods for oil leakage of hydraulic seal U Cup seal part

1. Oil leakage due to root wear The main reason for root wear is that the pre-compression is too large. Therefore, it is necessary to pay attention to the size of the inner and outer diameters of the sealing ring and the size of the sealing groove. It is necessary to reasonably select the inner and outer diameters of the sealing ring, the oil diameter and the size of the sealing groove, and pay attention to their coordination.

2. The dirt in the hydraulic oil and the dirt entering the hydraulic cylinder from the piston rod due to dust damage will often cause abnormal wear of the U Cup sealing ring. Therefore, in addition to keeping the cleanliness of the hydraulic oil, it should be A dust-proof ring is arranged on the extending end of the piston rod.

3. Oil leakage due to eccentric wear When the sealing ring is subjected to an eccentric load, a large amount of wear occurs in the position where the load is concentrated, while the other positions have little or no wear. Wear does not occur on the full circle of the lip, plus partial wear. The reasons for eccentric wear are: a. Bearing eccentric load (for example, a large clamping cylinder placed horizontally, eccentric load is formed due to the sag of the piston); b. The processing of the sealing groove is eccentric; c. The matching clearance is too large, resulting in the compression allowance Uneven (for example, the axis line of the piston and the piston rod is prone to be misaligned with the center line of the installed sealing ring in the hydraulic cylinder at this time); d. The hydraulic cylinder is not well assembled.

4. Oil leakage due to cracks When the U Cup seal is used under some severe conditions, the cracks shown in Figure 2 may appear. For example, U Cup used under high temperature and high pressure often produce this phenomenon, cracks lead to seal failure and oil leakage. It can be solved by choosing the appropriate material and using the rubber U Cup with cloth. In addition, the U Cup seal lip is not easy to crack.

5. The assembly is not easy to cut and seal, resulting in oil leakage. When inserting the piston with the U Cup into the cylinder, if the guiding tool is not used, there will be a compression allowance on the lip, and the cylinder hole will not be It is easy to chamfer, but it is difficult to push the piston in. Because it has to be pushed in by prying with a screwdriver, this will cause the sealing lip to turn over and crack, resulting in oil leakage. Therefore, be sure to use the split-type tapered guide tool shown below to install the U Cup. And when installing, be careful not to bring in dirt such as iron filings, dust, etc., so as not to strain the U Cup and cause oil leakage.

6. When the pressure of the U Cup exceeds 20MPa, a retaining ring should be used to prevent oil leakage from being cut into the gap.

7. The material of the seal is incompatible with the hydraulic oil.