Dual density earplug
View Patent ↗An earplug ( 10 ) that includes a soft foam body ( 12 ) and a stiffener ( 14 ) in the body, is produced by a method that has minimum steps and that results in an earplug of attractive design and that uses a minimum of material. One method includes molding an earplug body in a body cavity ( 52 ) while a mandrel ( 56 ) lies in the body cavity. After the foam material in the body cavity has at least partially solidified, the mandrel is removed, leaving an empty stiffener cavity ( 60 ) in the foam body ( 12 ). With the body remaining in the body mold ( 54 ), flowable stiffener material ( 14 A) is poured into the stiffener cavity of the body and allowed to solidify, to produce an earplug with a molded-in stiffener ( 14 ). Another method, results in an earplug ( 90 ) with a stem ( 95 ) having a rearwardly-projecting stem portion ( 96 ). This method includes molding a stem rear portion ( 96 ) in a stiffener cavity ( 110 ) while allowing stiffener material to project forward of the rear portion to form a stem free front portion ( 120 ). The free front portion is projected into a body cavity ( 104 ) while foam material in the body cavity is still plastically deformable.
1. A method for molding earplugs that each includes a body of resilient soft foam material and a stiffener in said body, comprising:
establishing foamable material of said body in a body cavity of a body mold, and allowing the foamable material to expand in the body cavity to form at least a major portion of said body;
establishing a majority of a quantity of flowable but solidifiable elastomeric stiffener material that is more than twice as stiff as said foamable material of said body when both materials solidify, in a stiffener cavity to form at least a major portion of said stiffener in said stiffener cavity, including establishing at least a front portion of the stiffener in said body cavity and allowing said materials of said body and stiffener to solidify and bond to one another, all without removing said body from the body cavity, and without removing said stiffer major portion from said stiffener cavity, whereby to minimize handling of parts.
2. A method for molding earplugs that each includes a body of soft foam material and a stiffener in said body, comprising:
establishing foamable material of said body in a body mold cavity that has an axis, while a mandrel lies in said body mold cavity and is centered on said axis, so the foamable material expands in the earplug cavity to form a body with an inner stiffener cavity where the mandrel lies;
after said foamable material of said body at least partially sets, removing said mandrel to leave said inner stiffener cavity empty, establishing a flowable and solidifiable stiffener material in said inner stiffener cavity, wherein when said stiffener material has solidified it is stiffer than said foam material, and allowing said stiffener material to solidify.
3. The method described in claim 2 including:
said step of establishing a flowable stiffener material in said inner stiffener cavity, includes leaving said body with an inner stiffener cavity in said earplug mold in which said foamable material expanded, while pouring said flowable stiffener material into said inner stiffener cavity.
4. A method for molding earplugs that each includes a body of soft foam material and a stiffener of stiffener material that is stiffer than said soft foam material, said stiffener having a front stiffener portion that lies in said body and a rear stiffener portion that projects rearward of said body and that forms a handle that is graspable during insert of the body in an ear canal and during removal of the body from the ear canal, comprising:
molding a rear portion of the stiffener in a cavity of a first mold, while establishing stiffener material at a front portion of the stiffener that projects out of the cavity and forms a projecting stiffener portion;
holding said soft foam material in a body cavity and, while said soft foam material is in a state wherein it is plastically deformable, moving said first mold and body cavity closer until said front portion of said stiffener lies in a rear portion of said body cavity, and allowing said materials to solidify.
5. A method for molding earplugs that each includes a body of resilient soft foam material and a stiffener in said body, comprising:
establishing foamable material of said body in a body cavity of a body mold, establishing a mandrel in said body cavity with the mandrel centered on a body cavity axis and allowing the foamable material to expand in the body cavity to form at least a major portion of said body with an inner stiffener cavity where the mandrel lies;
removing said mandrel to leave said stiffener cavity empty, and then pouring a quantity of flowable but solidifiable elastomeric stiffener material that is more than twice as stiff as said foamable material of said body when both materials solidify, in said stiffener cavity to form at least a major portion of said stiffener in said stiffener cavity, including establishing at least a front portion of the stiffener in said body cavity and allowing said materials of said body and stiffener to solidify and bond to one another, all without removing said body from the body cavity, and without removing said stiffer major portion from said stiffener cavity, whereby to minimize handling of parts.
6. The method described in claim 5 including:
inserting a front end of a post ( 80 ) into said stiffener before it solidifies, with a rear end of the post projecting rearward of the body mold cavity.
7. A method for molding earplugs that each includes a body of resilient soft foam material and a stiffener in said body wherein said stiffener has a rear portion that extends rearward of said body by at least a centimeter to form a handle, comprising:
establishing foamable material of said body in a body cavity of a body mold, and allowing the foamable material to expand in the body cavity to form at least a major portion of said body;
establishing a majority of a quantity of flowable but solidifiable elastomeric stiffener material that is more than twice as stiff as said foamable material of said body when both materials solidify, in a stiffener cavity that is separate from said body mold including forming a front portion of said stiffener so it is free of engagement with walls of said stiffener mold as said front portion of said stiffener is formed;
establishing at least a portion of the stiffener in said body cavity including pressing at least said front stiffener portion into said foamable material while said foamable material still lies in said body cavity, and allowing said materials of said body and stiffener to solidify and bond to one another.
8. The method described in claim 7 wherein:
said step of molding said stiffener includes molding said stiffener rear portion in a stiffener mold cavity while forming said stiffener front portion as a projection that projects forward of said stiffener mold cavity;
said step of pressing at least said front stiffener portion into said body mold cavity, occurs while said stiffener rear portion remains in said stiffener mold cavity to thereby provide an earplug with a molded stem.
9. The method described in claim 7 wherein:
said step of establishing said front projecting stiffener portion in said rear portion of said body cavity, includes pressing said front projecting stiffener portion into said body cavity while said projecting stiffener portion is heated above 130° F., whereby to establish a better bond of the stiffener to the body.
10. The method described in claim 7 wherein:
said step of establishing said front projecting stiffener portion in said rear portion of said body cavity, includes first allowing said foam to expand to fill a majority of its said body cavity, and then establishing said projecting stiffener portion in said body cavity.