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Molding Plastic Around a Thin Wire

IP.com Disclosure Number: IPCOM000049208D
Original Publication Date: 1982-May-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Boysen, RD: AUTHOR [+3]

Abstract

A plastic sleeve is molded concentrically around a thin wire by using a retractable metal insert surrounding the wire in the mold cavity.

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Molding Plastic Around a Thin Wire

A plastic sleeve is molded concentrically around a thin wire by using a retractable metal insert surrounding the wire in the mold cavity.

In the manufacture of wire-matrix print heads and many other applications, a thin, flexible wire 1 on the order of 0.3 mm diameter must be placed accurately in the center of a plastic sleeve 2 having a length of 10 mm or more. Fig. 1 shows an injection mold assembly 3 into which thin wire 1, brazed at one end to barrel 4, has been inserted. The wire runs through a small hole in retractable plunger 5, which is held toward barrel 4 by spring 6.

As plastic material 7 (Fig. 2) is injected into mold 3, it flows through holes 8 in barrel 4 and forces plunger 5 downward against the force of spring 6. This gradual retraction holds wire 1 firmly in place as sleeve 2 of material 7 is being formed around it, so that the wire cannot be bent out of position. Shoulder 9 stops the travel of plunger 5 when the full length of sleeve 2 has been achieved.

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