Seal for rubber molds

Claim 2

A mold unit for flashless molding of composite parts, said mold unit including first and second mold assemblies, at least one portion of said first assembly and one portion of said second assembly having generally oppositely directed surface portions defining the interior of a molding cavity in the closed position of said mold, a land on a portion of said second assembly for engaging a downwardly facing, radially extending surface of a relatively rigid insert element constituting one of said composite parts, means on said second assembly for receiving and supporting a portion of uncured rubber to be forced into said molding cavity, said first assembly including inner and outer concentrically disposed mold parts arranged for axial movement relative to each other, a land on said first assembly adapted to engage an upwardly facing portion of said radially directed surface, axially extending means forming a compressible, resilient connection between said relatively movable mold parts, a circumferentially extending annular seal ring support means in one of said movable parts, a lubricous, stiff but resilient seal ring positioned on said support means and having a working surface adapted to engage an oppositely directed surface of said other movable part under a given force to create a snug but sliding fit, means associated with said one of said relatively movable mold parts for confining said seal ring on all the surfaces thereof except said working surface, and means for adjusting the confinement of said seal ring in order to increase said given force.

Claim 3

A mold unit as defined in claim 1 wherein said seal ring comprises polytetrafluoroethylene.

Claim 4

A mold unit as defined in claim 1 wherein said means for adjusting the confinement of said seal ring comprises a threaded adjustment ring having a connection with said one movable mold part so as to be movable axially thereof and which further includes force applying means disposed between said seal ring and said adjustment ring.

Claim 5

A mold unit as defined in claim 1 wherein at least one of said axially movable parts has a tapered surface communicating with the interior of said molding cavity, said seal ring being closely spaced apart from said tapered surface.

Claim 6

A mold unit for flashless molding of an article having composite parts, said mold including first and second mold part units, one of said mold part units being adapted to remain fixed and having portions thereof for supporting a relatively stiff portion of the element to be molded, portions of said one mold part unit also defining at least a portion of the molding cavity in which said article is to be formed and the other of said mold part units having two mold elements urged apart from each other by resilient means, one of said mold elements including an annular surface portion of substantial axial extent and the other mold element being adapted for movement therealong, said other mold element having a portion of reduced axial extent adapted to be received in guiding relation to said annular surface portion, said other mold element also including a shoulder for receiving a stiff but resilient sealing ring, a sealing ring made from a lubricous material and seated upon said shoulder, a positioning element disposed atop said sealing ring and having a surface thereof engaging one surface of said sealing ring, whereby said sealing ring is confined on three surfaces and exposed for sealing contact with said annular surface of said one mold element, and an adjustment ring received in threaded relation on said other mold element, said adjustment ring being axially movable and having portions engaged with said positioning element along a surface opposite from the surface engaging said sealing ring, whereby said adjustment ring may be moved axially to adjust the axial force on said sealing ring and thereby vary the position of said mold contacting surface so as to control the working clearance between said sealing ring and said annular surface portion of said one mold element.

Claim 7

A mold unit for flashless molding of an article having composite parts, said mold including first and second mold part units, one of said mold part units being adapted to remain fixed and having portions thereof for supporting a relatively stiff portion of the element to be molded, portions of said one mold part unit also defining at least a portion of the molding cavity in which said article is to be formed and the other of said mold part units having two mold elements urged apart from each other by resilient means, one of said mold elements including an annular surface portion of substantial axial extent and the other mold element being adapted for movement therealong, said other mold element having a portion of reduced axial extent adapted to be received in guiding relation to said annular surface portion, said other mold element also including a shoulder for receiving a stiff but resilient sealing ring, a sealing ring made from a lubricous material and seated upon said shoulder, a positioning element disposed atop said sealing ring and having a surface thereof engaging one surface of said sealing ring, whereby said sealing ring is confined on three surfaces and exposed for sealing contact with said annular surface of said one mold element, and an adjustment ring received in threaded relation on said other mold element, said adjustment ring being axially movable and having portions engaged with said positioning element along a surface opposite from the surface engaging said sealing ring, whereby said adjustment ring may be moved axially to adjust the axial force on said sealing ring and thereby vary the position of said mold contacting surface so as to control the working clearance between said sealing ring and said annular surface portion of said one mold element.