What factors influence the shape of the sealing ring grooves?

The design of the sealing ring grooves needs to take into account multiple factors comprehensively to ensure sealing performance, service life and processing feasibility. The following are the key factors that affect the shape of the grooves and their specific roles:

I. Types and Material Characteristics of Sealing Rings

Sealing Ring Types

O-ring: Commonly uses rectangular grooves, as they have a simple structure and uniform compression.

Y-ring/Lip Ring: Requires designing trapezoidal or dovetail grooves to match the lip structure and ensure the lip tightly adheres to the cover under pressure.

U-ring: Uses grooves with guiding angles to prevent the sealing ring from flipping under high pressure.

Combined Seals (such as Strobel, Gland Rings): Requires designing composite grooves, integrating support rings and sealing lips, such as stepped grooves or irregular grooves.

Material Characteristics

Hardness: Harder materials (such as 90 Shore A) can reduce the groove width, while softer materials (such as 60 Shore A) require wider grooves to prevent extrusion.

Elastic Modulus: High elastic materials (such as silicone rubber) allow for a smaller compression ratio, and the groove depth can be appropriately increased.

Thermal Stability: High-temperature materials (such as fluororubber) need to consider the thermal expansion coefficient, and the groove size should be reserved for expansion space.

 wear Resistance: For dynamic sealing scenarios, the surface roughness of the groove needs to be optimized (such as Ra ≤ 0.8 μm) to reduce wear. Temperature range

High temperature: Material thermal expansion may cause changes in the compression rate of the sealing ring, which requires compensation through groove depth adjustment (e.g., reducing the groove depth by 0.1 to 0.3 mm).

Low temperature: Material contraction may lead to leakage, requiring an increase in the initial compression rate or the selection of a low-temperature flexible material (such as silicone rubber).

Medium properties

Corrosive medium: Select corrosion-resistant materials (such as PTFE-coated O-rings), and design a smooth groove surface (Ra ≤ 0.4 μm) to reduce medium retention.

Lubricating medium: Reduce the roughness of the groove surface to reduce friction; for non-lubricating media, increase the groove width to reduce wear.

High-pressure gas: Design a gas erosion prevention structure (such as adding ventilation holes at the bottom of the groove).

III. Motion mode and direction

Repetitive motion

The groove width should meet the rolling requirements of the sealing ring (usually 1.1 to 1.3 times the wire diameter), and control the groove depth to prevent crawling.

High-speed motion requires optimizing the groove radius (radius 0.3 to 1 mm) to reduce stress concentration.

Rotary motion

Axial sealing requires the design of a stepped or labyrinth groove to prevent the sealing ring from being pressed into the gap.

Radial sealing requires controlling the groove depth to the ratio of the groove depth to the shaft diameter (usually the groove depth ≤ 0.5 times the shaft diameter).

Composite motion

For swing + rotation conditions, design an irregular groove (such as elliptical) to adapt to multi-directional deformation.

IV. Assembly and processing constraints

Assembly method

Radial assembly: The groove needs to be designed with a guiding angle (usually 30° to 45°) to facilitate installation.

Axial assembly: Reserve installation space (such as the groove width being larger than the sealing ring diameter by 0.5 to 1 mm).

Processing method

Milling: Suitable for processing rectangular grooves, but control the bottom round corner (radius ≤ 0.5 mm).

Grinding: Can achieve high-precision grooves (such as Ra ≤ 0.2 μm), but has a higher cost.

Electrical Discharge Machining (EDM): Applicable to hard materials or complex-shaped grooves (such as irregular grooves).

Cost limitations

Simple shapes (such as rectangles) have low processing costs and are suitable for mass production; complex shapes (such as trapezoids) require special tools and have higher costs.

V. Sealing performance requirements

Leakage rate control

High-pressure sealing requires the design of multiple grooves (such as double O-ring structure) or labyrinth sealing.

Vacuum sealing requires controlling the roughness of the groove surface (Ra ≤ 0.1 μm) to reduce gas permeation.

Friction and wear

Low friction requirements (such as hydraulic cylinders) require optimizing the surface treatment of the groove (such as hard chrome plating) or selecting self-lubricating materials (such as PTFE).

High wear requirements (such as construction machinery) require increasing the hardness of the groove (such as quenching treatment).

Life expectancy

Long-life design requires increasing the groove width to reduce sealing ring compression fatigue, or using a combined sealing structure to distribute stress.

VI. Standards and norms

International standards

ISO 3601: Specifies the tolerance of groove dimensions for O-ring grooves (such as groove width tolerance ± 0.1 mm).

DIN 3760: For hydraulic system sealing ring grooves, recommends a trapezoidal groove angle of 75°.

Industry standards

Aerospace: Must meet the NAS1613 standard, with the groove surface requiring anodized treatment.

Food and medicine: Must comply with FDA standards, with the groove material being non-toxic and easy to clean.

VII. Environmental factors

Vibration and shock

Design a loosening prevention structure (such as adding a spring at the bottom of the groove) or increase the groove depth to absorb vibration.

Radiation and chemical pollution

In the nuclear industry, select anti-radiation materials (such as ethylene propylene rubber), and design sealing grooves to prevent radiation leakage.

In the chemical field, design anti-corrosion coatings (such as polytetrafluoroethylene spraying) or use all-metal grooves.

The shape of the groove can be optimized to achieve reliable sealing, long service life, and controllable cost.

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