Claims
- 1. A method for making a shaft seal of the .Iadd.molded lip .Iaddend.type including an annular elastomeric body.[.,.]. .Iadd.having .Iaddend.a molded lip and the molded lip having .Iadd.a sealing edge and axial sides on opposites of said sealing edge and .Iaddend.a liner of sintered polytetrafluoroethylene, comprising:
- (a) molding.[., at a temperature in the range of from about 300.degree. to 450.degree. F.,.]. an annular elastomeric body .Iadd.at a temperature at which the elastomeric body will flow and the polytetrafluoroethylene will not.Iaddend.; and
- (b) simultaneously with said molding step, forming a ring of sintered polytetrafluoroethylene into a liner on said elastomeric body in the shape of .[.a.]. .Iadd.the .Iaddend.molded lip and bonding said liner to .Iadd.the surface of both axial sides of the molded lip of .Iaddend.said elastomeric body .Iadd.by hydraulic pressure exerted by the elastomer of the elastomeric body during formation of the molded lip during said molding step.Iaddend..
- 2. The method according to claim 1 wherein said simultaneously forming step comprises lining said body for at least 0.060 inch on each axial side of said molded lip.
- 3. The method according to claim 1 wherein said simultaneously forming step includes forming hydrodynamic pumping elements on a shaft-engaging surface of said liner.
- 4. The method according to claim 1 wherein said simultaneously forming step comprises placing said ring of sintered polytetrafluoroethylene in a standard mold cavity having a molded-lip groove of the type for use in making an elastomeric, molded lip seal, and forcing elastomeric material into said mold cavity from behind said ring to force said ring against and into said molded-lip groove to form said ring as a polytetrafluoroethylene liner with a molded lip.
- 5. The method according to claim 4 wherein said placing step comprises placing said ring in said mold cavity at a location spaced away from said molded-lip groove such that said ring is out of contact with said molded-lip groove.
- 6. The method according to claim 4 wherein said placing step comprises placing a polytetrafluoroethylene ring having a thickness of about 0.010-0.050 inch in said mold cavity.
- 7. The method according to claim 4 wherein said placing step includes placing said ring in said cavity such that at least a portion thereof extends radially out into the cavity a sufficient distance such that said portion will extend past said molded-lip groove during said forcing step.
- 8. The method according to claim 7 wherein said simultaneously forming step comprises lining said body for at least 0.060 inch on each axial side of said molded lip.
- 9. The method according to claim 8 wherein said simultaneously forming step includes forming hydrodynamic pumping elements on a shaft-engaging surface of said liner.
- 10. The method according to claim 9 wherein said placing step comprises placing a polytetrafluoroethylene ring having a thickness of about 0.010-0.050 inch in said mold cavity.
- 11. The method according to claim 10 wherein said placing step comprises placing said ring in said mold cavity at a location spaced away from said molded-lip groove such that said ring is out of contact with said molded-lip groove.
- 12. The method according to claim 1 wherein said molding step comprises compression molding said elastomeric body from a pre-form of elastomer, and said forming step comprises forming a flat ring of sintered polytetrafluoroethelene into said liner.
- 13. A method for making a shaft seal of the .Iadd.molded lip .Iaddend.type including an annular elastomeric body.[.,.]. .Iadd.having .Iaddend.a molded lip, and the molded lip having a liner of sintered polytetrafluoroethylene, comprising the steps of:
- (a) compression molding.[., at a temperature in the range of from about 300.degree. to 450.degree. F.,.]. said elastomeric body from an elastomer pre-form.Iadd., at a temperature at which the elastomer pre-form will flow and the polytetrafluoroethylene will not, .Iaddend.while simultaneously foming said liner and bonding said formed liner .[.to.]. .Iadd.on the surface of .Iaddend.said elastomeric body, and
- (b) said forming step comprising:
- (1) placing, beneath said pre-form, a ring of sintered polytetrafluoroethylene in a mold cavity having .Iadd.a wall surface with .Iaddend.a molded-lip groove .Iadd.formed therein .Iaddend.with at least a portion of said ring extending radially out into the seal cavity a sufficient distance such that it will extend .Iadd.from a portion of said wall surface located on a first side of said groove .Iaddend.past said groove .Iadd.onto a second portion of said wall surface located on an opposite side of the groove .Iaddend.when formed in the direction of said groove, and
- (2) closing the mold to cause said elastomer to flow and .[.force.]. .Iadd.exert a hydraulic pressure forcing .Iaddend.said ring against and into said groove, forming said ring .[.as.]. .Iadd.into .Iaddend.a liner .[.with a.]. .Iadd.having the shape of said .Iaddend.molded lip.
- 14. The method according to claim 13 wherein said placing step comprises placing said ring in said mold cavity at a location spaced away from said molded-lip groove such that said ring is out of contact with said molded-lip groove. .Iadd.
- 15. A method for making a shaft seal of the type including an annular elastomeric body and a liner of sintered polytetrafluoroethylene on a shaft engaging surface of said seal, comprising the steps of:
- (a) placing a ring of sintered polytetrafluoroethylene on a core that forms a portion of a mold cavity of a mold, said core having at least one recess, with axial sides, in a surface thereof which contacts and defines the shaft engaging surface of said seal:
- (b) placing a pre-form of elastomer in said mold cavity above said ring; said pre-form having a volume greater than the volume of the mold cavity when closed;
- (c) compression molding said elastomeric body from said pre-form, at a temperature at which the elastomer will flow and the polytetrafluoroethylene will not, while simultaneously forming said liner from said ring and bonding said formed liner onto a surface of said elastomeric body, said forming step comprising forcing said elastomer to flow against said ring and hydraulically force said ring against and into said at least one recess to form said liner with a ridge, having axial sides on opposite sides of an edge thereof and corresponding to the shape of the recess in the mold surface that defines the shaft engaging surface of said seal; and
- (d) opening the mold and removing the seal therefrom. .Iaddend. .Iadd.
- 16. The method according to claim 15 wherein said at least one recess includes a hydrodynamic pumping element groove and wherein said ridge is a hydrodynamic pumping element. .Iaddend. .Iadd.17. The method according to claim 16 wherein said at least one recess is a plurality of hydrodynamic pumping element grooves and wherein said corresponding ridge is a
- plurality of hydrodynamic pumping elements. .Iaddend. .Iadd.18. The method according to claim 15 wherein said surface of said core is a conical surface. .Iaddend. .Iadd.19. The method according to claim 15 including placing an annular metal shell in said mold cavity and bonding said elastomeric body to said shell. .Iaddend. .Iadd.20. The method according to claim 15 wherein said at least one recess includes at least one edge where two flat surfaces of said recess meet with a v-shaped cross-section. .Iaddend. .Iadd.21. The method according to claim 15 wherein the cross-sectional shape of the radially innermost portion of
- said at least one recess is v-shaped. .Iaddend. .Iadd.22. The method according to claim 15 wherein said ring placing step includes placing said ring in said cavity such that at least a portion thereof extends radially out into the cavity a sufficient distance such that said portion will
- extend past said recess during said forcing step. .Iaddend. .Iadd.23. The method according to claim 22 wherein said simultaneously forming step comprises lining said body for at least 0.060 inch on each axial side of said recess. .Iaddend. .Iadd.24. The method according to claim 23 wherein said ring placing step comprises placing said ring in said mold cavity at a location spaced away from said recess such that said ring is out of contact with said recess. .Iaddend. .Iadd.25. The method according to claim 24 wherein said pre-form placing step comprises placing said pre-form directly on top of said ring. .Iaddend. .Iadd.26. The method according to claim 25 wherein said surface of said core is a conical surface. .Iaddend. .Iadd.27. The method according to claim 25 including placing an annular metal shell in said mold cavity and bonding said elastomeric body to said shell. .Iaddend. .Iadd.28. The method according to claim 27 wherein at least one said recess includes at least one edge where two flat surfaces of said groove meet with a v-shaped cross-section. .Iaddend.
.Iadd.CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation of application Ser. No. 313,273, filed Oct. 21, 1981, and now abandoned, and which is a reissue application for U.S. Pat. No. 4,171,561 which was issued on Oct. 23, 1979 on application Ser. No. 746,392. Application Ser. No. 746,392 was filed on Dec. 1, 1976. .Iaddend.
US Referenced Citations (19)
Foreign Referenced Citations (2)
Number |
Date |
Country |
46-23681 |
Jul 1971 |
JPX |
467935 |
Jun 1937 |
GBX |
Continuations (1)
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Number |
Date |
Country |
Parent |
313273 |
Oct 1981 |
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Reissues (1)
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Number |
Date |
Country |
Parent |
746392 |
Dec 1976 |
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