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1. Oil seal representation method
Common representation methods: Oil seal type-inner diameter-outer diameter-height-material such as: TC40*62*12-NBR indicates that the inner diameter of the inner diameter of the lip skeleton is 40 outer classic 62 thickness and 12 materials are the oil seal of the chore rubber.
2. Material of skeleton oil seal
Dingya rubber (NBR): wear resistance and oil-resistant (cannot be used in polar media) temperature resistance: -40 ~ 120 ℃
Hydrogenated Dentye Rubber (HNBR): wear resistance, oil resistance, aging resistance, temperature resistance: -40 ~ 200 ° C (stronger than NBR temperature resistance)
Flublatin (FKM): acid and alkali, oil-resistant (all oil), temperature resistance: -20 ~ 300 ° C (oil resistance than the previous two)
Polyurethane rubber (TPU): wear resistance, aging resistance, temperature resistance: -20 ~ 250 ℃ (good aging resistance)
Silicon Rubber (PMQ): heat-resistant, cold-resistant, low-deformed small mechanical strength, temperature resistance: -60 ~ 250 ℃ (excellent temperature resistance)
Polytetrafluoroethylene (PTFE): Various media such as good chemical stability, acid and alkali, oil and other media, wear -resistant high temperature and high temperature, high mechanical strength
Generally speaking, the commonly used materials for perfect china oil seal design bone leaf oil seals are butyl rubber, fluorine rubber, and silicone rubber. The effect is better when PTFE is added to bronze. , Steck et al.
Third, distinguish skeleton oil seal model
The oil seal of the C -type skeleton can be divided into five types: SC type, TC type, VC type, KC type, and DC type, namely single lip skeleton oil seal, lip skeleton oil seal, single lipless inner skeleton oil seal , Oil seal with no spring skeleton in the lip, oil seal in the skeleton in the lips
The G -shaped skeleton oil seal is a thread -shaped shape. Its type is the same as the C -type. It is only modified into a thread -shaped shape on the outside. It is similar to the role of the O -type circle. Fixed oil seal does not loosen
The oil seal of the B -type skeleton is that there are rubber materials in the inside of the skeleton or no rubber inside and outside the skeleton. No glue will make the heat dissipation performance better
Type A skeleton oil seal is a prefabricated oil seal. The structure is relatively complicated than the above three types, which is characterized by better pressure performance
Fourth, the sealing principle and application of the skeleton oil seal
• A total of three parts of the skeleton oil seal: self -tight spring, sealing subject, strengthening the skeleton
• The sealing principle of skeleton oil seal: Due to the oily film controlled between the oil seal and the shaft, this oil film has fluid lubrication characteristics.
• Sealing original interpretation: Under the action of the skeleton oil seal, the stiffness of the oil film just makes the oil film and air contact end form a new moon surface, preventing the leakage of the working medium, thereby achieving the sealing of the rotating shaft. The sealing ability of the oil seal depends on the thickness of the sealing mask, which is too large, and the oil seal is leaked; the thickness may be too small, which may cause dry friction, which may cause oil seal and axis. Essence Therefore, during installation, some oils must be applied on the sealing ring, and the skeleton oil seal is vertical and the axis heart line is perpendicular. Damage. During operation, the lubricant in the shell seeps slightly to achieve the formation of the cover.
Fifth, the role of skeleton oil seal
Generally, the parts that need to be lubricated in the transmission parts areolate the parts of the contribution. It will not leak lubricating oil. It is usually used for rotating shafts. It is a rotating shaft lips densely seal. The skeleton is like the reinforcement in the concrete component, which plays an enhanced role and enables the oil seal to maintain the shape and tension. According to the skeleton type, it can be divided into inner skeleton oil seal, outer skeleton oil seal, and exposed skeleton oil seal. The skeleton oil seal is made of high -quality bond rubber and steel plate, with stable quality and long service life.
1. Prevent sediment, dust, water and other invasion of the bearing from the outside;
2. Limit the lubricating oil in the bearing. The requirements for oil sealing are that the size (inner diameter, outer diameter, and thickness) shall meet the requirements; the request has appropriate elasticity, which can be stuck appropriately to play a sealing role; Oil or water, etc.), long service life.
Six, the choice of oil seal
The choice of oil sealing should be based on the sealing medium and working conditions. The sealing medium needs to select the material of the oil seal. The working conditions mainly consider using pressure, working line speed, and working temperature range.
When selecting the material of the oil seal, the compatibility of the material on the working medium, the adaptability of the working temperature range, and the ability to follow the rotating axis at high speed of the rotation axis. The temperature of the lip margin is higher than the temperature of the working medium at 20 ~ 50 ° C during the work medium, and you should pay attention when selecting the oil seal material.
The use pressure of ordinary oil seals generally does not exceed 0.05MPa. When the work pressure exceeds this value, a pressure -resistant oil seal should be used.
Under the same diameter conditions, the oil seal manufactured by different materials is different from the speed of rotation line rotation. The line speed range used in oil seal is generally less than 15m/s.
The working range of oil seal is related to the material used for oil seal: the material is -40 ~ 120 ° C at the time of the chores (NBR), the Alek rubber (ACM) -30 ~ 180 ° C, and the fluorine rubber (FPM) -25 ~ 300 ° C.
7. Design requirements for the corresponding axis and cavity
Design of axis:
1. The surface roughness. Because the speed of the axis is different from the amount of oil, the roughness of the axis is too large or too small, which will affect the leakage and wear of the oil seal. The surface roughness of the shaft is RZ1.0 ~ 5.0 μm; RA0.2 ～ 0.8 μm. Seal 2.5 to 1.6 μmrz with oil on the rotating shaft.
2. Hardness, the surface hardness of the rotating shaft is generally ≥35HRC. When the medium is dirty, there are pollution impurities from the outside world, or the axis speed> 12m/s, the surface hardness of the axis should be above 55HRC, and the depth of the shaft surface quenching layer> 0.mm.
3. Facking of the axis, the recommended value of 15 ° ~ 30 °,; the principle of allowing the oil seal to be installed without damaging the oil seal lip margin.
4. The processing of the axis, the correct axis processing is the decisive factor to ensure the normal operation of the sealing system. The appropriate oil seal shaft processing method is to grind it in horizontally, and the diamond sandpaper is polished. The unsuitable processing method is to process it on the lathe, super fine processing, rolling processing, and diamond sandpaper polishing (sandpaper moves at the axis).
5. The material of the axis is mainly ordinary carbon structure steel, such as C35 and C45, and also cast iron, ceramic, resin plastic, but the axis of the latter three materials have defects on the sealing of the oil seal.
Design of the cavity:
1. The surface roughness, and the diameter tolerance are shown in the table below.
|
Site |
Diameter tolerance |
Surface roughness/mm |
||
|
Ra≤ |
Rz≤ |
|||
|
Seat hole |
Skeleton oil seal |
H11 |
3.2 |
12.5 |
|
Skeleton oil seal |
H8或H7 |
1.6 |
6.3 |
|
|
Rotating shaft |
h9或f9 |
0.8~0.4 |
3.2~1.6 |
|
2. Install the recommended value of 15 ° ~ 30 °.
3. The material of the cavity is steel or cast iron, and the outer peripheral is a rubber or metal oil seal. Generally, light alloys and resin thermal expansion coefficients are large, and it is suitable for oil sealing peripheral rubber.
4. The unsuitable cavity structure, such as stamping processing, is installed with a thread combination, and the open -type cavity.
Eight, the installation of oil seal
1. Before installation, the oil seal should be applied between the lips and the lithium -based lithium ester with molybdenum sulfide to prevent the axis from starting in an instant. As soon as possible, assemble. If the oil seal is not installed immediately, it is recommended to cover the oil seal with cloth coverage on it. Hands or tools with lithium -based fat must be clean.
2. The oil seal should be packed, and there must be no inclined phenomenon. It is recommended to use oil pressure equipment or sleeve tool installation. Don’t be too stressful, the speed is uniform and slow.
3. When the oil seal is installed, the oil or lubricant should be applied and the shaft end and shaft shoulder should be rounded.
4. When installing the oil seal, the end of the lip edge must be facing the sealing oil on the side.
5. When the oil seal is loaded into the seat hole, the dedicated tool should be pushed in to prevent the position from sinking.
6. Threads, bond slots, bonds, etc. of the lip edion of the oil seal should be taken to prevent lip margin damage and assemble it with a dedicated tools.
7. When removing oil sealing, avoid the surface and the surface of the internal and shaft of the cavity;
8. The use of oil seal, even if the appearance cannot be used, must be replaced by a new oil seal;
9. When there are bumps or rust on the surface of the axis, it must be repaired;
10. When loading the new oil seal, in order to leave the old lip contact site, the pads should be used to avoid the original friction marks.
