Method of making a two-component gasket

Claim 1

In the manufacture of a two-piece gasket comprising a thinner rigid component and a thicker preformed compressible component wherein the thicker component has two flat opposite major faces which are generally parallel to one another and a side surface between said major faces, and the thinner component is bonded to the side surface of the thicker component, a method of forming a reproducible, durable edge where the thinner component adjoins the thicker component, said method comprising, compressing said compressible component between mating mold halves which engage the major faces thereof, forming said thinner component in situ by an injection molding process wherein a flowable, hardenable resin is injected into a die cavity formed by said mold halves so that the resin contacts said side surface of said compressible component, providing an elongated narrow rib on at least one said mold half, said rib positioned adjacent the edge of said side surface of said compressible component, said rib defining a side edge of the cavity into which said resin is injected so that the resin flows up to and against said rib, applying pressure to said mold halves during said molding so that said rib locally deforms said compressible component beyond its elastic limit to a thickness less than that of the thinner component, said rib forming a dam preventing flow of said resin past it onto the major face of said compressible component thereby demarcating said edge, and causing said resin to rigidify within said cavity thereby to form said rigid component in situ, bonded to the side surface of the compressible component, and bounded by a groove formed by said rib.