Glyd ring belongs to the piston combined seal ring, and is also one of the most commonly used PTFE combined seals for hydraulic cylinders at present. What are the main characteristics of the glyd ring? What are the standard parameters for the installation of glyd ring? And what are the application fields of GRADE Circle? What is the surface roughness requirement of glyd ring?
What is the glyd ring
The glyd ring is composed of a low friction filled PTFE rectangular sealing ring and an O-ring, which plays a two-way sealing role
Classification
glyd ring for hole and glyd ring for shaft
Material
The selection of glyd ring generally depends on the materials of PTFE and O-ring to adapt to different working conditions. PTFE can be added with different materials and its content can be adjusted to change the nature of its work. The choice of O-ring is generally determined by temperature and medium.
Nitrile rubber, with a temperature range of - 40~120 ℃, is oil resistant. It is often used with PTEF+bronze materials, with high cost performance.
Fluorine rubber: temperature resistance - 20~250 ℃, oil resistance, corrosion resistance. Generally, the working condition with high requirements is to use fluorine rubber with PTFE carbon fiber.
Advantages of the glyd ring
1) Excellent static sealing performance.
2) A large extrusion gap can be allowed.
3) The friction is small, the friction generates less heat, and there is no creeping phenomenon.
4) The groove structure is simple and can be made into an integrated piston. The installation groove conforms to the international standard ISO7425/2.
5) Good wear resistance and long service life,
6) The mating surface will not adhere during a long period of inactivity or storage.
7) Suitable for most hydraulic oils and most modern hardware materials.
8) Excellent pressure resistance
Scope of application
Hydraulic system, reciprocating motion, under the conditions of high pressure, low pressure and high frequency, the sealing performance of heavy-duty two-way piston is very excellent. Suitable for long and short stroke, large fluid range, high temperature and large piston clearance.
Product application
It is suitable for piston seals with pressure on both sides, especially for large diameter pistons. It is recommended to be used in reciprocating and helical motions, such as injection molding machines, hydraulic presses, marine hydraulic systems, manipulators, grinders, metallurgical machinery, large oil cylinders, bulldozers, agricultural machinery, presses and other machine tools
Matters needing attention in the design of glyd ring
1) Design requirements for glyd ring groove
Reasonable seal ring groove design is a necessary prerequisite for the seal ring to play its advantages. Therefore, it is necessary to refer to the corresponding standards and specifications or the manual of Guangzhou Family for reasonable design of the groove. Here, it is necessary to remind that the size of the radial clearance will affect the sealing pressure. The shaft hole size and the cross section size of the glyd ring with different sizes and specifications may also affect the selection of the radial clearance, which requires special attention
The maximum gap dimension (mm) appears on the unpressurized side during operation
L | 100 BAR | 200 BAR | 400 BAR |
2.2 | 0.60 | 0.40 | 0.30 |
3.2 | 0.80 | 0.50 | 0.30 |
4.2 | 0.80 | 0.50 | 0.40 |
6.3 | 1.00 | 0.60 | 0.40 |
8.1 | 1.20 | 0.70 | 0.50 |
9.5 | 1.40 | 1.00 | 0.60 |
13.8 | 2.00 | 1.40 | 1.20 |
> 400 bar → gmax = H8/f8 | |||
2) Lead in angle design
In consideration of the later assembly of the Geying ring, the piston rod and the hydraulic red cylinder shall be designed with corresponding guide chamfers, so as to facilitate the assembly of the seal ring and not easily cause scratch or damage to the seal ring.
Glyd ring piston seal import chamfer
Import Chamfer | Import Chamfer | ||
L | S | L | S |
2.2 | 2.0 | 8.1 | 6.5 |
3.2 | 2.5 | 9.5 | 7.5 |
4.2 | 3.5 | 13.8 | 10.0 |
6.3 | 5.0 | ||
3) Roughness requirements
The reliability and service life of the seal ring largely depend on the quality and surface roughness of the sealing mating surface. Scratches and scratches will not only affect the sealing performance, but also increase the wear of the seal, causing premature seal failure
Static surface: Ra≤0.3μm Rt≤2.5μm
Dynamic surface: Ra≤1.6μm Rt≤6.3μm
In addition to the requirements for Ra and Rz of the sealing mating surface, in order to make the seal more durable, the bearing length ratio Rmr (c) of the contour of the mating surface must be controlled. It is generally required that Rmr (c)=about 70%.
Installation requirements of glyd ring
1) If the chamfer is not introduced into the piston rod, a mounting sleeve is required.
2) Deburr and chamfer, and cover the thread end of the bolt to prevent scratching the seal.
3) All workpieces shall be cleaned and free of ash, debris and other external particles.
4) 4) It is better to apply grease or oil to the sealing element during installation, so as to make the installation easier and more convenient. However, it is necessary to ensure the compatibility between sealing materials and these greases. Lubricants containing solid additives are not allowed to be used.
5) The installation tool used must be free from sharp edges.