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US 11,786,408 B2Granted
Push-in earplug and method of making the same using a mandrel
Assignee3M Innovative Properties Company
InventorsJacob H. Ely, Robert C. Coffin, James D. Brown
Life of this patent
Estimating the term…
Abstract
A push-in earplug is provided. The push-in earplug comprises an elongate core comprising a core material. The push-in earplug also comprises an outer layer comprising a foam material, the outer layer covering at least a portion of an outer surface of the elongate core. The push-in earplug also comprises a channel extending through the elongate core from a first end of the elongate core to the second end of the elongate core.
Claims20
A method of manufacturing an earplug, the method comprising:
- forming an earplug preform with a first end and a second end opposite the first end portion, the earplug preform comprising a substrate covered by a core layer and an outer layer, wherein the substrate is chemically inert with respect to a core material, and wherein the core material comprises a polyamide mixture comprising a polyamide and an impact modifier;
- positioning the earplug preform at least partially within a mold cavity;
- and
- applying heat to at least a portion of the mold cavity such that at least a portion of the outer layer expands and conforms to a shape of the mold cavity and the outer layer thermally bonds to the core layer;
- and
- removing the substrate, wherein, after the substrate is removed, the core layer has a channel extending from the first end to the second end.
3 more elements
A method of making an article, the method comprising:
- covering a substrate with a core layer, wherein the substrate comprises a first end and a second end, and the core layer substantially covers an outer surface of the substrate, and wherein the core layer comprises a mixture of a polyamide and an impact modifier;
- covering the core layer with an outer layer to prepare a preform having a first end portion and a second end portion, the outer layer comprises an expandable material having an activation temperature, and wherein the substrate comprises a material with a melting point above the activation temperature;
- positioning the first end portion of the preform in a first cavity of a mold and the second end portion in a second cavity of the mold, the first mold cavity having a diameter that is smaller than a diameter of the second mold cavity at its widest point;
- and
- increasing the temperature of the mold to at least the activation temperature of the expandable material to activate the expandable material within the second end portion to form the second end portion into a sound-attenuating portion.
2 more elements
A method of forming an earplug, the method comprising:
- forming a core layer with a first end and a second end, wherein the core layer has a hollow interior extending from the first end to the second end, and wherein the core layer is formed around a mandrel, and wherein forming comprises:
- extruding the core layer over the mandrel;
- laminating the core layer over the mandrel;
- dipping the mandrel into a core layer material;
- spraying a core layer material over the mandrel;
- or molding the core layer over the mandrel;
- covering the core layer with an expandable outer layer;
- activating the expandable outer layer, wherein activating the expandable outer layer comprises causing the expandable outer layer to expand and form a sound attenuating portion and a stem portion, and wherein a density of the earplug is greater at the first end than the second end;
- and wherein the hollow interior of the core layer is maintained during activation of the outer layer such that the earplug has a channel extending from the first end to the second end;
- and
- wherein the core layer comprises a mixture of a polyamide and an impact modifier.
8 more elements
Dependencies are inferred from the claim text.