WO2012152808A1 - Joint d'étanchéité à texture - Google Patents

Joint d'étanchéité à texture Download PDF

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Publication number
WO2012152808A1
WO2012152808A1 PCT/EP2012/058492 EP2012058492W WO2012152808A1 WO 2012152808 A1 WO2012152808 A1 WO 2012152808A1 EP 2012058492 W EP2012058492 W EP 2012058492W WO 2012152808 A1 WO2012152808 A1 WO 2012152808A1
Authority
WO
WIPO (PCT)
Prior art keywords
coating material
coating
contact surface
sealing element
seal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2012/058492
Other languages
English (en)
Inventor
Barbera Stellario
George POPOVICI
Bo Xiao ZHOU
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SKF AB
Original Assignee
SKF AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SKF AB filed Critical SKF AB
Publication of WO2012152808A1 publication Critical patent/WO2012152808A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J15/00—Sealings
    • F16J15/16—Sealings between relatively-moving surfaces
    • F16J15/32—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings
    • F16J15/3244—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings with hydrodynamic pumping action
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J15/00—Sealings
    • F16J15/16—Sealings between relatively-moving surfaces
    • F16J15/32—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings
    • F16J15/328—Manufacturing methods specially adapted for elastic sealings

Definitions

  • the present invention relates to the field of dynamic seals, for sealing a gap between relatively moving components. More specifically, the present invention relates to an elastomeric seal having a texturized contact surface, and to a method for manufacturing the seal.
  • Seals are used to prevent leakage between two environments and/or to prevent the ingress of particulate contaminants from one environment to another.
  • the seal In a dynamic seal, the seal has a surface that is in sliding contact with a moving counterface, and provides dynamic sealing. When the counterface is stationary, the seal provides static sealing.
  • a dynamic seal is an oil seal, which may be mounted between a shaft and the bore of a bearing housing.
  • the oil seal has an elastomeric sealing element with at least one lip that bears against the shaft surface.
  • the seal lip must remain in contact with the counterface. Therefore, friction occurs during dynamic conditions. The friction generates heat, leading to energy losses. The friction also leads to wear of the elastomeric material, which will ultimately cause a loss of sealing function.
  • lubrication of the contact interface is important.
  • a thin elasto-hydrodynamic oil film builds up between the seal lip and the moving counterface.
  • the oil film reduces the frictional forces. Therefore, one way of reducing friction in a dynamic seal is to ensure that the contact interface remains well lubricated.
  • the movable counterface may be provided with a texture that facilitates hydrodynamic pumping of the lubricant (oil) in the direction of the seal lip.
  • a texture that facilitates hydrodynamic pumping of the lubricant (oil) in the direction of the seal lip.
  • One such texture is disclosed in US3572730, whereby triangular asperities are provided on a rotatable counterface, to improve reverse pumping. It is also possible to provide such a texture on the seal lip.
  • a hydrodynamic pumping action is obtainable by means of helical ribs on a contact surface or surfaces of a seal lip.
  • helical ribs are provided at both the oil side of a seal lip and at the air side.
  • the main function of the helices is to prevent leakage, by pumping oil to the oil side of the seal.
  • the air-side helices pump the oil towards the seal lip, which therefore has the additional effect of keeping the lip contact interface supplied with lubricant.
  • Dynamic seals are also used in reciprocating applications, and it has been suggested to provide the contact surface of such seals with a surface texture.
  • a functional texture on a seal lip can have several benefits in terms of improving lubrication and/or reducing leakage.
  • One solution for reducing wear is to provide a wear-inhibiting coating on the surface texture.
  • a PTFE coating is suggested.
  • a disadvantage of providing a coating on a texturized surface is that the coating will lessen the texture. Indentations become less deep and protrusions become less high. The coating must therefore be provided in a thin layer, which increases the likelihood that the coating will get worn off. Also, when the texturized surface comprises e.g. micro-dimples, even a thin coating layer will clog the dimples, drastically impairing the functionality of the surface texture.
  • the present inventors have discovered that it is possible to provide the contact surface of an elastomeric sealing element with a wear-resistant surface texture, by introducing the texture into a wear-resistant coating that is applied on the contact surface.
  • the coating may be applied in a thickness that provides long-lasting resistance to wear, while the beneficial effects of the surface texture are reliably obtained, without any unpredictable clogging.
  • the present invention provides a method of manufacturing a coated elastomeric sealing element, the method comprising steps of;
  • ⁇ providing an elastomeric sealing element having a contact surface which, in use, is adapted to bear against a moveable counterface
  • Preferred elastomers for the sealing element include acrylate rubber, fluoro rubber, nitrile rubber, hydrogenated nitrile rubber, or mixtures of two or more thereof.
  • the contact surface of the elastomeric sealing element, prior to application of the coating is substantially smooth. This allows standard moulds to be used in the manufacture of the elastomeric sealing element.
  • the coating material preferably comprises a polymeric material such as polyurethane or polytetrafluoroethylene.
  • the coating material suitably has a hardness of between 90 Shore A and 25 Shore D.
  • the coating material is provided in a thickness that is sufficient to accommodate the height/depth of the texturing features to be provided.
  • the texturing features are distinct from mere surface roughness. They are deeper and may be specifically arranged on the surface to provide the beneficial effects.
  • the coating thickness lies between 0.05 and 1.00 mm.
  • the thickness can be measured by techniques known in the art and is measured from the contact surface of the elastomeric seal to an upper surface of the coating, which upper surface will bear against the counterface.
  • the texturing features may comprise indentations in the upper surface of the coating.
  • the indentations may be grooves or dimples with a depth of between 5 and 150 microns.
  • An appropriate thickness for the coating is then 0.1 to 0.3 mm.
  • the dimples may be spherical, cylindrical, square, rectangular, triangular, hexagonal, or any other suitable shape.
  • the dimples are provided in a predetermined array.
  • the predetermined array may be a regular array, adapted to enhance oil film formation.
  • the predetermined array may also be irregular, so as to provide a desired pressure differential across the contact interface, to promote pumping in a desired direction.
  • the indentations may also be provided with a non-predetermined distribution.
  • the texturing features may comprise protrusions, whereby an upper surface of the protrusions coincides with the upper surface of the coating.
  • the protrusions may be formed by ridges, such as helical ribs.
  • the ribs typically have a height of between 0.05 and 0.3 mm, whereby the coating may be provided in a thickness of 0.25 - 0.7 mm.
  • the protrusions may also be provided in a regular or irregular predetermined array, or with a non-predetermined distribution, as described above with reference to indentations.
  • the protrusions may be spherical in shape, or cylindrical, triangular, square, rectangular, etc.
  • the protrusions in the array have a height of 5 to 150 microns and the coating is suitably provided in a thickness of 0.15 to 0.35 mm.
  • the step of processing is carried out after a layer of coating material has been applied.
  • the texturing features as described above are created by removing material from the coating layer.
  • the step of processing may comprise laser etching or machining the texturing features into the coating material.
  • the coating material comprises a soluble filler and the step of processing comprises the dissolving soluble filler.
  • the soluble filler may contain sodium chloride crystals, which are removed to leave indentations in the surface of the coating, when they are washed (dissolved) away.
  • a deformation process may also be used to create the desired surface texture in the coating material.
  • the step of processing comprises stamping the texturing features into the coating material.
  • the coating material may comprise a blowing agent.
  • Blowing agents are used to produce bubbles in the coating material. If the bubble is formed close to the surface then it may be used to provide a void or dimple in the surface. If the bubble is below the surface then it may form a dome on the surface of the coating layer. Blowing agents include physical blowing agents such as CFCs, HCFCs, hydrocarbons (e.g. pentane, isopentane, and cyclopentane) and solid or liquid C0 2 .
  • the bubble/foam-making process often requires heat initiation.
  • the step of processing comprises initiating the blowing agent.
  • Chemical blowing agents such as isocyanate and water (which react to release C0 2 ) are especially useful for forming expanded polyurethanes.
  • Other examples include azo-, hydrazine and other nitrogen-based materials and sodium bicarbonate.
  • the blowing material may be distributed throughout the coating material and only selectively activated or initiated. In this way, the bubbles only form surface texture in a desired distribution on the coated surface.
  • the material forming the coating is a polymeric material
  • the curing treatment may be selectively applied to the coating material. In this way, uncured material can be removed from the surface to provide a surface texture in a desired distribution on the coated surface.
  • curing may be initiated before the step of processing the coating to create a surface texture.
  • the coating material can be hardened while the texture is formed.
  • the step of processing comprises deformation and/or machining of the coating material, these operations are performed before curing is complete.
  • stamping is suitably carried out while the coating is still uncured or only partially cured.
  • the step of processing the coating to provide a textured coating is performed as part of the step of providing the coating material on the seal contact surface.
  • the step of processing comprises providing a non-bonding agent on one or more portions of the contact surface, prior to application of the coating material.
  • a textured coating is created in that at least the portions of the contact surface provided with the non-bonding agent have a reduced amount of coating material thereon.
  • the step of processing comprises masking one or more portions of the contact surface, prior to application of the coating material.
  • the mask(s) used suitably constitute a "negative" of the desired surface texture.
  • the present invention also provides an elastomeric sealing element having a substantially smooth contact surface provided with a coating layer, wherein the coating layer has a surface texture comprising a plurality of dimples, protrusions, ribs and/or grooves.
  • the elastomeric sealing element may be adapted for use in a rotary seal, such as a shaft seal or a seal for a rolling element bearing, or may be adapted for use in a reciprocating seal. Such seals are well known in the art. Furthermore, an elastomeric sealing element according to the invention may be adapted for use in combination with a variety of lubricants such as oil, grease or water, depending on the application.
  • Figure 1 shows a cross-section of part of a seal according to the invention.
  • FIG 2 is a flowchart of a method according to the invention, used in the manufacture of the seal in Figure 1. Detailed Description
  • FIG 1 shows an example of a shaft seal 10 comprising a metal casing 15 to which an elastomeric sealing lip 20 has been bonded.
  • the seal is mounted in an annular gap between the bore of a bearing housing 30 and a shaft 35, whereby the sealing lip 20 has a contact surface 25 which bears against a counterface on the shaft 35.
  • the lip is preloaded with a garter spring 40.
  • an interface between the contact surface 25 and the shaft 35 is lubricated with a grease (not shown).
  • the contact surface 25 is provided with a wear-resistant coating material and has a surface texture comprising texturing features.
  • the texturing features are provided only in the coating material.
  • the texturing features provided on the contact surface are dimples.
  • the dimples have a diameter of approximately 30 microns, a depth of 10 microns, and have an essentially cylindrical geometry.
  • the dimples are provided in a regular array and cover approximately 20 percent of the contact surface area.
  • the dimpled texture promotes the formation of a thicker oil film under elasto-hydrodynamic sealing conditions; i.e. when the lip contact surface 25 is in sliding contact with the shaft 35.
  • a first step 210 the elastomeric sealing lip 20 is moulded from nitrile rubber in a standard mould.
  • the standard mould has substantially smooth surfaces which are not adapted to create any kind of surface texture on a surface of the lip.
  • the rubber lip is then cured.
  • a polymer coating material comprising polyurethane is applied to a predetermined surface of the elastomeric lip 20, which predetermined surface will serve as the lip contact surface 25 in use of the seal.
  • the coating is sprayed onto the predetermined surface in a thickness of approximately 0.25 mm.
  • the coating is then cured.
  • the described array of micro-dimples are laser etched into the coated contact surface 25.
  • a short-pulse Nd: YAG laser may be used, at a spot size of 30 microns.
  • the seal 10 is further assembled as known in the art; i.e. the lip 20 is bonded to the metal casing 15 and the garter spring is fitted.
  • the coated contact surface can be texturized after the elastomeric lip 20 has been bonded to the casing 15 and the garter spring 40 has been installed.
  • the dimpled surface texture on the contact surface provides low friction under dynamic sealing conditions, as is known from conventional texturized seals. Unlike such conventional seals, a seal according to the invention has significantly greater wear resistance and is able to provide the beneficial functionality for a considerably greater duration.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Manufacturing & Machinery (AREA)
  • Sealing With Elastic Sealing Lips (AREA)

Abstract

La présente invention concerne un élément d'étanchéité en élastomère et un procédé de fabrication d'un élément d'étanchéité en élastomère (20) ayant une surface de contact (25) qui comporte une texture de surface. Selon l'invention, la surface de contact (25) comporte un revêtement résistant à l'usure et la texture de surface est introduite dans le revêtement.
PCT/EP2012/058492 2011-05-12 2012-05-09 Joint d'étanchéité à texture Ceased WO2012152808A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP2011002350 2011-05-12
EPPCT/EP2011/002350 2011-05-12

Publications (1)

Publication Number Publication Date
WO2012152808A1 true WO2012152808A1 (fr) 2012-11-15

Family

ID=46125420

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2012/058492 Ceased WO2012152808A1 (fr) 2011-05-12 2012-05-09 Joint d'étanchéité à texture

Country Status (1)

Country Link
WO (1) WO2012152808A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023040418A1 (fr) * 2021-09-16 2023-03-23 舍弗勒技术股份两合公司 Dispositif d'étanchéité et son procédé de fabrication

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3572730A (en) 1969-06-13 1971-03-30 Timken Co Wear surface for facilitating lubrication of elements in engagement therewith
US4239243A (en) * 1979-04-04 1980-12-16 Garlock Inc. Molded lip seal with polytetrafluoroethylene liner and method for making the same
US6276691B1 (en) 1998-02-27 2001-08-21 Nok Corporation Oil seal
US20040113366A1 (en) 2002-10-04 2004-06-17 Ina-Schaeffler Kg Lip-type shaft seal
DE102008039805A1 (de) * 2008-08-19 2010-02-25 Kaco Gmbh + Co. Kg Dichtring, insbesondere Radialwellendichtring, sowie Verfahren zu seiner Herstellung

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3572730A (en) 1969-06-13 1971-03-30 Timken Co Wear surface for facilitating lubrication of elements in engagement therewith
US4239243A (en) * 1979-04-04 1980-12-16 Garlock Inc. Molded lip seal with polytetrafluoroethylene liner and method for making the same
US6276691B1 (en) 1998-02-27 2001-08-21 Nok Corporation Oil seal
US20040113366A1 (en) 2002-10-04 2004-06-17 Ina-Schaeffler Kg Lip-type shaft seal
DE102008039805A1 (de) * 2008-08-19 2010-02-25 Kaco Gmbh + Co. Kg Dichtring, insbesondere Radialwellendichtring, sowie Verfahren zu seiner Herstellung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Koyo Engineering Journal English", article "Effects of Surface Dimples on Friction Coefficient of Reciprocating Model Lip Seals"

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023040418A1 (fr) * 2021-09-16 2023-03-23 舍弗勒技术股份两合公司 Dispositif d'étanchéité et son procédé de fabrication

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