Stress relieved molded cover assembly and method of making the same
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorHyman Kessler
Life of this patent
Estimating the term…
Abstract
Hoop stresses are relieved to eliminate the formation of cracks produced ing the molding of a thermoplastic fitment cover about a support ring structure. Heated plastic is directly molded about the support ring to form any desired cover shape. Hoop stresses created in the cover as the fitment shrinks upon cooling are relieved by means of an interfacing cushion of elastomer. Variation in elastomer configuration provides the flexibility of allowing the elastomer to be "snapped-on" or to be directly molded onto the support ring.
Claims11
A stress-relieved, molded hollow cover, comprising:
- A support ring having a marginal recess area;
- An elastomer band disposed within said marginal recess surrounding a portion of said support ring;
- A hollow portion of thermoplastic material injection molded directly about and enveloping the band of elastomer, interlocked with said ring and axially extending from said ring, said hollow portion cooperating with said ring to form said hollow cover.
In the injection molding of a plastic fitment directly onto a support ring having a tubular end region to receive the fitment, a method for reducing the formation of hoop stresses and thereby eliminating fitment cracks comprising the steps of:
- a. providing said support ring tubular end region with a plurality of holes spaced about a marginal recess;
- b. placing the support ring into working relationship with an injection molding machine;
- c. providing a layer of elastomer surrounding said support ring end region;
- d. placing a fitment mold about the support ring end section;
- e. injecting a heated thermoplastic directly into the mold and surrounding said elastomer and allowing the thermoplastic to fill the mold;
- f. allowing the thermoplastic to cool about said support ring;
- and
- g. removing said directly molded thermoplastic fitment from said injection machine.
In the injection molding of a plastic fitment directly onto a receiver base, said receiver base having two tubular ring sections to receive the fitment, a first inner support ring section and a second outer ring section, each of said ring sections having a plurality of holes spaced about a marginal end region of said tubular sections, a method for eliminating hoop stresses and thereby eliminating fitment cracks and for sealing interlockingly together the fitment with the support ring, comprising the steps of:
- placing the receiver base into a working relation with an injection molding machine;
- placing a pre-formed elastomer mold about the inner support ring;
- injecting an elastomer into said pre-form mold and surrounding a portion of said support and allowing the mold and said support ring spaced holes to be filled with said elastomer;
- removing said elastomer mold;
- placing a fitment mold about the support ring end section;
- injecting a heated thermoplastic directly into the mold and surrounding said elastomer, and allowing the thermoplastic to fill the mold and the outer support ring spaced holes;
- allowing the thermoplastic to cool about the support ring;
- and
- removing said directly molded thermoplastic fitment from the injection machine.
Dependencies are inferred from the claim text.