Molding an elastomeric ring while bonding it to a metal case and to a fluorocarbon washer

• US 4,555,376 A
• Filed: 03/12/1984
• Issued: 11/26/1985
• Est. Priority Date: 03/12/1984
• Status: Expired due to Fees

• Current Assignee: Federal-Mogul Corporation (Apollo Global Management, Inc.)
• Original Assignee: Federal-Mogul Corporation (Apollo Global Management, Inc.)
• Inventors: Butler, John D.
• Primary Examiner(s): Weston, Caleb
• Application Number:
  US06/588,718
• Time in Patent Office: 624 Days
• Field of Search: 156/245, 156/500, 425/DIG. 47, 29/527.1, 29/469.5, 264/266, 264/268, 249/57, 249/83, 249/85, 249/88
• US Class Current: 264/266
• CPC Class Codes: B29D 99/0053 Producing sealings B29D99/0085 takes precedence
• CPC Class Codes: B29L 2031/26 Sealing devices, e.g. packaging for pistons or pipe joints
• CPC Class Codes: Y10S 425/047 Seal ring
• CPC Class Codes: Y10T 29/49906 Metal deforming with nonmetallic bonding
• CPC Class Codes: Y10T 29/4998 Combined manufacture including applying or shaping of fluent material

Abstract

Method and apparatus for molding an elastomeric component of a shaft seal while bonding it to a fluorocarbon seal lip member. The lip member is initially shaped as a flat washer, and a radially outer portion is flexed during molding to a frustoconical shape. Positive retention of the fluorocarbon washer during molding is assured. Radially inner portion of the fluorocarbon washer rests on a planar annular mold ledge, its radially outer portion overhanging a frustoconical mold surface. A ring of uncured elastomer is located above that radially outer portion and radially inwardly from the outer periphery of the ledge. The radially inner portion has a horizontal toothed mold portion with a series of concentric sharp tooth edges. This directly engages the upper surface of the washer and clamps it firmly and immovably against the ledge. When the mold is closed, the elastomer flows and forces the outer portion of the washer down on frustoconical mold surface while bonding elastomer to washer.

Claims

1. A mold comprising:

a base molding member having a radially outer case-supporting portion and, spaced inwardly and away therefrom, a sloping frustoconical mold surface which ends at an inwardly extending upper ledge,

a two-part upper mold assembly having first and second mold members,

said first mold member having a lowermost generally horizontal toothed portion with a series of concentric sharp tooth edges in line with the radially inward portion of said ledge, and a cylindrical wall portion leading up from the outer edge of said toothed portion to an upper radially outwardly extending flange having a lower surface and an upper surface,

said second mold member having a cylindrical inner wall engaging the cylindrical wall portion of said first mold member, a ledge at the upper end thereof against which the lower surface of said outwardly extending flange can abut, a spacing means leading from the outer edge of said ledge to an upper radially inwardly extending surface,

spring means engaging said upper surface of said first upper mold member and urging it down against said ledge of said second mold member, but compressible so that said second mold member can move down relative to said first mold member after said first mold member bottoms against said upper ledge of said base molding member,

said second upper mold member also having a mold-cavity-defining lower surface lying radially outwardly from its said cylindrical inner wall and extending downwardly for closing off said mold cavity,

said cylindrical wall portion of said first mold member normally extending down well below the lower extremity of the cylindrical inner wall of said second mold member and defining an annular corner portion against which a ring of uncured elastomer is placed just prior to molding, and

mold closing means for forcing said upper mold assembly down to bottom said toothed portion and forcing said second mold member down relatively to said first mold member against the pressure of said spring means.

2. The mold of claim 1 wherein there is flash-preventing means between said first mold member'"'"'s cylindrical portion and said cylindrical inner wall of said second mold member for preventing flow of material between them.

3. The mold of claim 2 wherein said flash-preventing means comprises an annular recess, rectangular in cross-section, in said cylindrical portion of said first mold member and a polytetrafluoroethylene O-ring, rectangular in cross-section, in and completely filling said recess and with its outer periphery matching exactly the inner periphery of said cylindrical inner wall of said second mold member.

4. The mold of claim 1 wherein said series of concentric sharp tooth edges comprises each said edge having a radially inner vertical wall and a radially outer frustoconical wall.

5. A mold for molding an elastomeric component of a shaft seal while bonding it to a metal case and to a fluorocarbon seal lip member that is initially in the shape of a flat washer and a portion of which is, during molding, flexed to a desired frustoconical shape, said mold assuring positive retention of the fluorocarbon washer during molding, comprising:

a base molding member having a case-supporting portion and, spaced away therefrom, an inwardly sloping frustoconical mold surface which ends at an inwardly extending upper ledge, said fluorocarbon washer being placed on said upper ledge prior to molding and overhanging said frustoconical mold surface,

a two-part upper mold assembly having a first mold member with a lowermost generally horizontal toothed portion having a series of concentric sharp tooth edges for directly engaging the upper surface of said fluorocarbon washer and clamping it firmly and immovably against said upper ledge and a radially outer generally vertical cylindrical portion leading up from the outer edge of said toothed portion to an upper radially outwardly extending flange having a lower surface, an upper surface and an outer cylindrical rim, said vertical cylindrical portion having an annular recess with a sealing O-ring therein,

said upper mold assembly also having a second mold member having a generally vertical cylindrical inner wall engaging said vertical cylindrical portion and said O-ring to seal against passage of flash, a ledge at the upper end thereof against which the lower surface of said outwardly extending flange can abut, a cylindrical portion abutting said outer cylindrical rim of said outwardly extending flange and extending beyond the upper surface of said outwardly extending flange a substantial distance, and an upper radially inwardly extending surface, having axially extending openings therethrough, with spring means in said openings for engaging said upper surface of said first upper mold member and urging it down against said ledge of said second mold member,

said second upper mold member also having a mold-cavity-defining lower surface extending radially outwardly from said cylindrical inner wall and a downwardly extending portion for closing off said mold cavity,

said vertical cylindrical wall of said first upper mold member extending down below the lower surface of said second upper mold member and defining an annular corner portion against which a ring of uncured elastomer is placed just prior to molding, so that the elastomer does not interfere with said direct engagement of said fluorocarbon washer by the toothed portion of said first upper mold member,

heating means for heating said mold members to molding and curing temperatures, and

mold closing means for forcing said upper mold assembly down so that said toothed portion first engages the radially inner portion of said fluorocarbon washer and bites into it and retains it against movement while said mold closing means forces said second mold member down relatively to said first mold member, overcoming the pressure of said spring means, causing said elastomer to flow and closing off the mold cavity, while forcing the outer portion of said fluorocarbon washer down on said first frustoconical mold surface where the frustoconical portion of said washer is bonded to said elastomer.

6. The mold of claim 5 wherein said annular recess is rectangular in cross-section and said sealing O-ring is rectangular in cross-section and completely fills said recess and matches in periphery the inner periphery of said cylindrical inner wall of said second mold member.

7. The mold of claim 6 wherein said sealing O-ring is made of polytetrafluoroethylene.

8. The mold of claim 5 wherein said series of concentric sharp tooth edges comprises each said edge having a radially inner vertical wall and a radially outer frustoconical wall.

9. A mold comprising:

a base molding member having an inwardly sloping first frustoconical mold surface which ends at an inwardly extending upper ledge for holding a fluorocarbon washer therein,

a movable two-part upper mold assembly, having an inner mold member and an outer mold member,

said inner mold member having a lowermost generally horizontal toothed portion aligned with a radially inner portion of said upper ledge and having a series of concentric sharp tooth edges,

said outer mold member being mounted for vertical movement relative to said inner mold member with yieldable means between said inner and outer mold members for urging said inner mold member downwardly relative to said outer mold member

said outer mold member also having a mold-cavity-defining lower surface and a downwardly extending portion for closing off said mold cavity,

means on said upper mold assembly for retaining a ring of uncured elastomer radially outwardly from said upper ledge, so that the elastomer does not interfere with direct engagement of said fluorocarbon washer by the toothed portion of said inner mold member, and

mold closing means for forcing said upper mold assembly down so that said toothed portion engages and bites into the radially inner portion of said fluorocarbon washer and retaining it against movement, said mold closing means then forcing said outer mold member down relatively to said inner mold member, overcoming the pressure of said yieldable means, and closing off the mold cavity.

10. The mold of claim 9 having flash flow preventing means between said inner and outer mold members.

11. The mold of claim 10 wherein said flash preventing means comprises mating, relatively slidable cylindrical walls on both the inner and outer mold members, a rectangular shaped annular recess in one said wall, and a rectangular O-ring completely filling said recess and made from a material having greater thermal expansion than the material from which the inner and outer mold members are made.

12. A mold for molding an elastomeric component of a shaft seal while bonding it to a fluorocarbon seal lip member that is initially in the shape of a flat washer and a portion of which is, during molding, flexed to a desired frustoconical shape, said mold assuring positive retention of the fluorocarbon washer during molding, comprising

a base molding member having an inwardly sloping first frustoconical mold surface which ends at an inwardly extending upper ledge, said fluorocarbon washer being placed on said upper ledge prior to molding and overhanging said frustoconical mold surface,

a movable two-part upper mold assembly having an inner mold member and an outer mold member,

said inner mold member having a lowermost generally horizontal toothed portion having a series of concentric sharp tooth edges for directly engaging the upper surface of said fluorocarbon washer and clamping it firmly and immovably against said upper ledge

said outer mold member being mounted for vertical movement relative to said inner mold member with yieldable means between said inner and outer mold members for urging said inner mold member downwardly relative to said outer mold member

said outer mold member also having a mold-cavity-defining lower surface and a downwardly extending portion for closing off said mold cavity,

means on said upper mold assembly for retaining a ring of uncured elastomer radially outwardly from said upper ledge, so that the elastomer does not interfere with said direct engagement of said fluorocarbon washer by the toothed portion of said inner mold member,

heating means for heating said mold members to molding and curing temperatures, and

mold closing means for forcing said upper mold assembly down so that said toothed portion first engages the radially inner portion of said fluorocarbon washer and bites into it and retains it against movement while said mold closing means forces said outer mold member down relatively to said inner mold member, overcoming the pressure of said yieldable means, causing said elastomer to flow, closing off the mold cavity, and forcing the outer portion of said fluorocarbon washer down on said frustoconical mold surface where its frustoconical portion is bonded to said elastomer.

13. A mold for molding an elastomeric component of a shaft seal while bonding it to a metal case and to a fluorocarbon seal lip member that is initially in the shape of a flat washer and a portion of which is, during molding, flexed to a desired frustoconical shape, said mold assuring positive retention of the fluorocarbon washer during molding, comprising

a base molding member having a lowermost mold ledge joined by a step to an intermediate ledge for initial placement upon said intermediate ledge of a radial flange of a case member, said radial flange being bent during molding to help to close off said mold and to achieve bonding of elastomer to the inner portion of said radial flange which is bent, during mold closure, to a frustoconical shape, the outer portion of said radial flange thereby being forced down against said lowermost ledge, said base molding member also having a short vertical portion leading from the inner edge of said intermediate ledge to an upwardly and inwardly sloping first frustoconical mold surface which ends at an upper ledge, said upper ledge extending inwardly to an inner, second frustoconical mold surface, said fluorocarbon washer being placed on said upper ledge prior to molding and overhanging and frustoconical mold surface,

a two-part upper mold assembly having a first upper mold member with a radially inner frustoconical wall which, upon mold closure, mates with said second frustoconical mold surface, a lowermost generally horizontal toothed portion having a series of concentric sharp tooth edges for directly engaging the upper surface of said fluorocarbon washer and clamping it firmly and immovably against said upper ledge, a radially outer generally vertical cylindrical portion leading up from the inner edge of said toothed portion to an upper radially outwardly extending flange having a lower surface and an upper surface, said vertical cylindrical portion having an annular recess with a sealing O-ring therein filling said recess and made of material having greater expansion than the material from which the mold assembly is made,

said upper mold assembly also having a second mold member having a generally vertical cylindrical inner wall engaging said vertical cylindrical portion and said O-ring to seal against passage of flash, a ledge at the upper end thereof against which said outwardly extending flange abuts, a cylindrical surface at the outer periphery of said outwardly extending flange and considerably higher than the thickness of said flange, and an upper radially inwardly extending surface, having axially extending openings therethrough, with spring means in said openings for engaging said upper surface of said first upper mold member and to urge it down against said ledge of said second mold member,

said second upper mold member also having a mold-cavity-defining lower surface and a downwardly extending portion for abutting said case'"'"'s radial flange during mold closure forcing it down against said lowermost ledge, and for closing off said mold cavity,

said vertical cylindrical wall of said first upper mold member extending down below the lower surface of said second upper mold member and defining an annular corner portion against which a ring of uncured elastomer is placed prior to molding, so that the elastomer does not interfere with said direct engagement of said fluorocarbon washer by the toothed portion of said first upper mold member,

heating means for heating said mold members to molding and curing temperatures, and

mold closing means for forcing said upper mold assembly down so that said toothed portion engages the radially inner portion of said fluorocarbon washer and bites into it and retains it against movement while said mold closing means then forces said second mold member down relatively to said first mold member, overcoming the pressure of said spring means, causing said elastomer to flow and forcing said downwardly extending portion against said metal case to close off the mold cavity, forcing the outer portion of said fluorocarbon washer down on said first frustoconical mold surface and to bond said washer to said elastomer.

14. A method for molding an elastomeric component of a shaft seal while bonding it to a metal case and a fluorocarbon seal lip member while shaping the fluorocarbon seal lip member that is initially in the shape of a flat washer having a radially inner portion and a radially outer portion, so that said radially outer portion is, during molding, flexed to a desired frustoconical shape, said method assuring positive retention of the fluorocarbon washer during molding, comprising:

emplacing said fluorocarbon washer with said radially inner portion thereof resting on a stationary planar annular mold ledge and said radially outer portion thereof over-hanging a frustoconical mold surface,

seating an annular metal case on an outer stationary portion of said mold,

locating a ring of uncured elastomer on a movable mold member above the radially outer portion of said washer and radially inwardly from the outer periphery of said planar annular ledge,

engaging the radially inner portion of said washer with a relatively movable generally horizontal mold portion, at least one of said planar annular mold ledge and said generally horizontal mold portion having a series of sharp tooth edges, directly engaging said radially inner portion of said fluorocarbon washer on at least one surface thereof with said edges and clamping it in direct engagement firmly and immovably between said annular planar ledge and said generally horizontal mold portion, and

closing the mold while causing said elastomer to flow against said case and to flow against and to force said radially outer portion of said fluorocarbon washer onto said frustoconical mold surface while bonding said elastomer to said washer.

15. A method for molding an elastomeric component of a shaft seal while bonding it to a fluorocarbon seal lip member that is initially in the shape of a flat washer having a radially inner portion and a radially outer portion, said radially outer portion of said washer being flexed during molding to a desired frustoconical shape, said method assuring positive retention of the fluorocarbon washer during molding, comprising

emplacing said fluorocarbon washer with said radially inner portion thereof resting on a planar annular mold ledge and said radially outer portion thereof overhanging a frustoconical mold surface,

locating a ring of uncured elastomer having the radially outer portion of said washer and radially inwardly from the outer periphery of said ledge,

engaging said radially inner portion of said washer with a generally horizontal toothed mold portion having a series of concentric sharp tooth edges, directly engaging the upper surface of said fluorocarbon washer with said edges and clamping it firmly and immovably against said ledge, and

closing the mold while causing said elastomer to flow and to force the outer portion of said fluorocarbon washer down on said frustoconical mold surface while bonding said elastomer to said washer.