Method and apparatus for bonding polytetrafluoroethylene to a metal substrate and articles thereby produced
AssigneeMather Seal Company
InventorEugene A. Duncan
Life of this patent
Estimating the term…
Abstract
Polytetrafluoroethylene (PTFE) is bonded to a metal substrate such as an oil seal casing via an intermediary bonding layer of fluorinated ethylene propylene (FEP). Induction heating is used to rapidly melt the FEP and PTFE without degrading their physical properties. The induction heating unit is preferably controlled by a temperature signal representing the temperature of the metal substrate.
Claims16
A method for bonding a first seal element comprising polytetrafluorethylene having predetermined physical properties to a second element capable of being heated by an induction heating apparatus so as to form a radial lip seal, wherein said method comprises:
- providing a layer of a fluorinated resin adhesive having a melting point lower than said polytetrafluorethylene between said first and second elements;
- contacting said first and second elements;
- induction heating said second element to a temperature of at least the melting temperature of polytetrafluoroethylene in less than about 60 seconds so as to melt said resin;
- maintaining said second element at said temperature of at least the melting temperature of polytetrafluoroethylene for a time period in which only a minor portion of said polytetrafluoroethylene is melted, said melting of said minor portion of said polytetrafluorethylene being insufficient to significantly alter the predetermined physical properties of unmelted portions of said first element;
- controlling said induction heating with a temperature signal representing the temperature of said second element;
- and
- cooling said first and second elements so as to form a bond therebetween.
A method for manufacturing a seal by bonding a sealing element wafer comprising polytetrafluoroethylene to an inductively heatable substrate, said wafer having first and second opposed sides separated by a predetermined thickness, said wafer being formed with predetermined physical properties, wherein said method comprises:
- interposing a layer of a fluorinated resin having a melting point below the melting point of said wafer between said substrate and at least a portion of said first side of said wafer;
- and
- applying inductively generated heat and external pressure to said wafer, to said substrate and to said resin to form a bond between a limited portion of said first side of said wafer and said substrate by rapidly melting said resin and only a portion of said thickness of said wafer adjacent said limited portion of said first side without melting said second side during formation of said bond by limiting application of said heat and external pressure to said bond within predetermined ranges for controlled periods of time such that said predetermined physical properties of unmelted portions of said wafer are not significantly altered.
A radial lip seal, comprising:
- a wafer having predetermined physical properties and comprising polytetrafluoroethylene, said wafer having first and second opposed sides separated by a predetermined thickness, said wafer forming a contact sealing surface;
- an inductively heatable substrate for supporting said wafer;
- and
- a bond formed between said first side of said wafer and said substrate, said bond comprising a region of a fluorinated resin adhesive intermingled with said polytetrafluoroethylene, said adhesive having a melting point less than the melting point of said wafer, said bond being formed by heating by induction and cooling said substrate, said adhesive and said polytetrafluoroethylene, said bond extending through only a portion of said thickness of said wafer and separated from said contact sealing surface such that said predetermined physical properties of said wafer at said contact sealing surface are substantially unaffected by formation of said bond.
Dependencies are inferred from the claim text.