Molded lip seal with polytetrafluoroethylene liner and method for making the same

• US 4,171,561 A
• Filed: 12/01/1976
• Issued: 10/23/1979
• Est. Priority Date: 12/01/1976
• Status: Expired

• Current Assignee: Garlock Inc. (Enpro Industries Incorporated)
• Original Assignee: Garlock Inc. (Enpro Industries Incorporated)
• Inventors: Denton, Dennis N., Bainard, Dean R.
• Primary Examiner(s): Smith, Robert J.
• Application Number:
  US05/746,392
• Time in Patent Office: 1,056 Days
• Field of Search: 29/527.1, 29/558, 29/559, 264/275, 264/271, 264/156.3, 277/152, 277/153, 277/134
• US Class Current: 29/527.1
• CPC Class Codes: B29C 43/027 having an axis of symmetry B29C43/102 takes precedence
• CPC Class Codes: B29C 43/18 incorporating preformed parts or layers, e.g. compression moulding around inserts or for coating articles B29C43/206 takes precedence
• CPC Class Codes: B29D 99/0053 Producing sealings B29D99/0085 takes precedence
• CPC Class Codes: B29K 2021/00 Use of unspecified rubbers as moulding material
• CPC Class Codes: B29L 2031/26 Sealing devices, e.g. packaging for pistons or pipe joints
• CPC Class Codes: F16J 15/328 Manufacturing methods specially adapted for elastic sealings moulding B29C
• CPC Class Codes: F16J 15/3284 characterised by their structure; Selection of materials
• CPC Class Codes: Y10S 277/924 Deformation, material removal, or molding for manufacture of seal
• CPC Class Codes: Y10S 425/047 Seal ring
• CPC Class Codes: Y10T 29/4998 Combined manufacture including applying or shaping of fluent material

Abstract

A shaft seal (and method for making the same) of the type having an annular elastomeric body, a molded lip, and the molded lip having a liner of sintered polytetrafluoroethylene bonded thereto. The elastomer is molded simultaneously with the polytetrafluoroethylene liner being formed and bonded to the elastomer. The method for making the seal employs the same mold used to make common, molded lip elastomeric seals.

Claims

1. A method for making a shaft seal of the type including an annular elastomeric body, a molded lip and the molded lip having a liner of sintered polytetrafluoroethylene, comprising:

(a) molding, at a temperature in the range of from about 300°

to 450°

F., an annular elastomeric body; 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 molded lip and bonding said liner to said elastomeric body.

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 type including an annular elastomeric body, 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°

to 450°

F., said elastomeric body from an elastomer pre-form while simultaneously forming said liner and bonding said formed liner to 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 a molded-lip groove with at least a portion of said ring extending radially out into the seal cavity a sufficient distance such that it will extend past said groove when formed in the direction of said groove, and

(2) closing the mold to cause said elastomer to flow and force said ring against and into said groove, forming said ring as a liner with a 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.