Noise-prevention grommet and process for manufacturing the same

A method of manufacturing a grommet, the grommet being formed of an elastic material and comprising a small tube portion through which a wiring harness is passed, having an edge at one end thereof, a frustoconical tube portion extending from the edge of the small tube portion and having a flared-out portion and inner and outer surfaces, wherein on the outer surface of the frustoconical tube portion is formed a recess for fitting into an automobile body panel, an internal tube portion through which the wiring harness is passed, wherein the internal tube portion depends from the edge of the small tube portion, extending substantially along an axial direction in the frustoconical tube portion and having an open edge and an outer edge, and a closing portion having a through-hole being substantially centrally located, the method comprising:

• a) integrally forming the small tube portion and the frustoconical tube portion in a first mold in the presence of a vulcanizing agent, whereby a grommet core part which is half-vulcanized is provided;
• b) integrally forming the internal tube portion and the closing portion in a second mold in the presence of a vulcanizing agent, whereby a grommet sub-part which is half-vulcanized is provided, the grommet core part and the grommet sub-part having corresponding binding sites;
• c) placing the grommet core part and the grommet sub-part into a third mold, such that the corresponding binding sites are in contact;
• and
• d) heating the third mold until the grommet core part and the grommet sub-part become fully vulcanized, whereby the corresponding binding sites are melted and bound to yield the grommet.

A method of manufacturing a grommet, the grommet being formed of an elastic material and comprising a small tube portion through which a wiring harness is passed, having an edge at one end thereof, a frustoconical tube portion extending from the edge of the small tube portion and having a flared-out portion and inner and outer surfaces, wherein on the outer surface of the frustoconical tube portion is formed a recess for fitting into an automobile body panel, an internal tube portion through which the wiring harness is passed, wherein the internal tube portion depends from the edge of the small tube portion, extending substantially along an axial direction in the frustoconical tube portion and having an open edge and an outer edge, and a closing portion having a through-hole being substantially centrally located, comprising:

• a) integrally forming the small tube portion and the frustoconical tube portion in a first mold in the presence of a vulcanizing agent, whereby a grommet core part which is half-vulcanized is provided;
• b) forming the closing portion in a second mold in the presence of a vulcanizing agent, whereby a grommet sub-part which is half-vulcanized is provided, the grommet core part and the grommet sub-part having corresponding binding sites;
• c) placing the grommet core part and the grommet sub-part into a third mold, such that the corresponding binding sites are in contact;
• and
• d) heating the third mold until said parts become fully vulcanized, whereby the corresponding binding sites are melted and bound to yield the grommet.