Most people know that there is a part called O-ring seal design, it is mainly used in cylinder, cylinder and other cylinder design, it is characterized by simple structure, easy disassembly, low price, pressure resistance, corrosion resistance, high and low temperature resistance and other characteristics, can work between -120℃~200℃.
Let's learn about the O-ring selection design calculation and other issues.
First, O-type sealing ring selection design criteria:
1. The O-ring can be regarded as a wearing part, and its installation position should be fully considered in the design to facilitate disassembly, so it is often installed near the end of the shaft or hole, and the entrance is often treated with a longer Angle, which can be chamfer 20°x2, or 30°x2.
2. The specifications of the O-type sealing ring should match the corresponding groove depth and width to ensure that the friction between the sealing ring and the cylinder wall is the minimum when the sealing ring is used as a dynamic seal, and does not affect the performance and effect of pressure resistance and leakage prevention of the seal, otherwise it is prone to excessive friction resistance, reduced life, and the sealing ring is easy to extrude the groove. Tear or conversely too loose, leakage and other bad effects.
3. In order to enhance the sealing effect, multiple sealing rings can be used to meet the sealing requirements in the same position segment
4. The clearance between the shaft and the hole of the sealing ring should be reasonable. If necessary, a stop ring can be added in the groove to ensure the installation reliability of the sealing ring.
Second, the depth and width of the O-ring installation groove design
Trench depth and width design according to national standards:
1. When the outer diameter of the O-type sealing ring is the nominal diameter of the selection parameter, the groove standard is GB1235-1976;
2. When the nominal diameter of the O-ring is used as the selection parameter, the groove standard is: GB/ T34452.1-2005;
Note: When can the sealing ring groove size be selected according to the "1" standard? When can the trench size be selected according to the "2" standard?
Select groove size according to "1" standard when using radial seal; Select the groove size according to the "2" standard for axial sealing. The so-called radial seal means that when the cylinder hole diameter is certain, the sealing ring is installed on the piston or drive shaft in a radial seal way; The so-called axial seal refers to the way in which the sealing ring is installed between the shaft end or the hole end face and the two plane joint surfaces.
O-ring mounting shaft and aperture size calculation
Note: Generally, the unilateral clearance between the shaft and the hole of the installation seal is treated as 0.125, so that the actual size of the shaft and hole can be calculated combined with the size of the sealing groove above, and the specifications of the sealing ring are fully determined. Here are some examples:
The diameter is Ø35, the sealing place is the axle diameter of the end cover and the static seal of the hole, and it does not withstand high pressure, then the sealing ring with a smaller diameter is preferable, and the specification can be determined by looking at the table for Ø35x1.9, so that the size of the shaft and the hole can be calculated
According to the table, the groove size corresponding to the line diameter of 1.9 is: depth 1.5, width 2.5, then the shaft size is 35- (0.125x2) =34.75, and the shaft diameter at the bottom of the groove is 34.75- (1.5x2) =31.75. Of course, the size of the hole is the same as the nominal outer diameter of the sealing ring.