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Interwoven Resistance Heater Element

IP.com Disclosure Number: IPCOM000008043D
Publication Date: 2002-May-14
Document File: 2 page(s) / 8K

Publishing Venue

The IP.com Prior Art Database

Abstract

This invention broadly relates to the construction of cylindrical ohmic heating elements. In particular, this invention relates to the use of cylindrical ohmic heating elements to heat the nozzle of an injection mold hot runner. The proposed heater is to be made by weaving an insulated resistive element (made of NICHROME, or similar) wire in a cylindrical shape. (Sleeve) Woven tubes will be made from suitable resistance wire inter-woven with high temperature ceramic composites. An inherent characteristic of the woven tubular element is that it does not require any clamping means to hold it in place.

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This is the abbreviated version, containing approximately 57% of the total text.

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Field of the Invention

       This invention broadly relates to the construction of
cylindrical ohmic heating elements. In particular, this
invention relates to the use of cylindrical ohmic heating
elements to heat the nozzle of an injection mold hot runner.

Summary of the Prior Art

       Currently bi-metal type heaters are used quite
extensively to heat nozzles, wherein two materials are used to
sandwich the cable heater between the inner and outer cylinder.
The inner sleeve is heated, and caused to expand. The outer
sleeve is made of titanium and is used to restrict expansion,
forcing the inner sleeve to fold around the nozzle body. This is
a complex, complicated, and very expensive assembly that
involves precision machined parts. Tolerances are critical for
proper functioning of this heater. An out of tolerance assembly
does not perform the gripping function, but rather opens the
inner sleeve and therefore reduces heat sinking ability of the
heater; this in turn overheats the heating elements.

Summary of the Invention

       The primary objective of the invention is to provide a
cylindrical ohmic heating element for use with a nozzle of an
injection mold hot runner.

Advantages of this invention over prior art include:
1. Self clamping
2. Easy to install
3. Flexibility in manufacturing

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4. No machining involved - fully automated process
5. Reliability ensured by design
6. Reduced cost
7. Non-hygroscopic (MgO currently used absorbs
moisture)
8. Low labor manufacture

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