Stock material or miscellaneous articles – All metal or with adjacent metals – Honeycomb – or with grain orientation or elongated elements...
Reexamination Certificate
2000-11-10
2002-09-17
Zimmerman, John J. (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Honeycomb, or with grain orientation or elongated elements...
C428S603000, C029S897320, C029S521000, C072S363000, C072S379200, C072S379600
Reexamination Certificate
active
06451447
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to multilayer metal foil shields which have utility as heat shields and as acoustic shields.
BACKGROUND OF THE INVENTION
Multilayer metal foil insulation has been used for many years, as illustrated by U.S. Pat. No. 1,934,174. Such metal foil insulation has typically been used in high temperature applications for reflective heat insulation. In those applications, the layers of metal foils are embossed to provide separation between the layers, and the stack of layers are protected in a container or rigid cover to prevent the stack of metal foils from becoming compressed at any portion, which would decrease the heat insulation value of the stack.
U.S. Pat. No. 5,011,743, discloses that multilayer metal foil insulation can provide enhanced performance as a heat shield when a portion of the multilayer metal foil is compressed to provide a heat sink area through which heat is collected from the insulating portions of the stack and dissipated from the heat shield. Such multilayer metal foil heat shields are formed from a stack of embossed metal foil layers by compressing portions of the stack to create the desired heat sink areas. The layers are attached to each other or stapled together to prevent the layers from separating. The heat shields and acoustic shields formed according to the disclosure of the U.S. Pat. No. 5,011,743 are typically compressed in the heat sink areas and cut to a desired pattern. Such multilayer metal foil heat shields do not normally have sufficient structural strength for stand-alone use in many applications. For many applications, the metal foil heat shields are typically attached to a structural support member or pan to provide a final assembly which is then placed in service as a heat shield or acoustic shield. The support members are typically metal pans or stampings or metal castings. Typical applications for such heat shield assemblies include automotive heat shield applications.
The disclosures of the above patents are incorporated herein by reference.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a multilayer metal foil insulation structure which has sufficient structural strength to function as a stand alone unitary heat shield or acoustical shield without the necessity of the multilayer metal foil insulation being preassembled on a support member.
The multilayer metal foil structures of this invention comprise at least three metal layers at least two of which are metal foil layers having a thickness of 0.006 in. (0.15 mm) or less. It is generally preferred that the structures of this invention contain at least three layers of metal foil and more preferably will typically contain five to seven layers of metal foil. Preferably, the metal foil layers will be 0.005 in. (0.12 mm) or less with 0.002 in. (0.05 mm) metal foil being a preferred thickness for interior layers in many shield applications. In addition to the layers of metal foil, optional protective exterior layers of metal sheet on one or both sides of the shield structure can be included. The metal sheets have a thickness greater than 0.006 in. (0.15 mm) and up to about 0.050 in. (1.27 mm). The thickness of the optional exterior protective metal sheet is selected such that it can be formed and shaped as part of the unitary multilayer metal foil shield structure according to this invention. Preferably the protective exterior metal sheet layers will be between about 0.008 in. (0.20 mm) and about 0.030 in. (0.76 mm). In the multilayer metal foil structures of this invention, one or more layers of such metal sheets may be placed between the metal foil layers, if desired, for additional structural strength of the final unitary multilayer metal foil shield structure. For some shield applications the multilayer metal foil structure can be made entirely of metal foils having a thickness of 0.006 in. or less, without the use of any thicker metal sheet layers. The multilayer metal foil structures have surprising structural strength and rigidity when forge formed according to this invention.
The multilayer metal foil shield structures according to this invention are shaped by a forming process which includes providing a preform of at least three layers of metal sheet, at least two of which layers are metal foil layers having a thickness of 0.006 in. (0.15 mm) or less, where the layers are spaced apart to provide gaps between the layers, forming the multilayer preform over a shaping mold whereby a first portion of the preform is held in position to maintain the spaced apart positions to maintain desired gaps between the layers, a second portion of the preform is placed under tensile stress to shape that second portion of the preform into ridges or corners to form the desired three dimensional form and a third portion of the preform is placed under compression to shape that third portion of the preform into a wall section positioned at an angle from the plane of the first portion and an edge section to interlock the layers together in that third portion. The second portion provides the transition from the first portion having spaced apart layers and the third portion having compressed, interlocked layers. The third portion comprises a wall section and an edge section. It is preferred that the layers be compressed and interlocked together in both the wall section and the edge section. However, in some configurations of the structures of this invention, the layers may be compressed and shaped to form the wall section, but the layers are not interlocked together in part or all of the wall section. But in such configurations, the layers are always compressed and interlocked together in the edge section where the layers are preferably folded, curled or rolled together at the edge to form a bead along the edge of the structure. The compressed portion provides three dimensional shape of the structure and imparts structural strength to the overall multilayer metal foil structure by folding or wrinkling the sheets of the preform into interlocking relationship in the third portion to form a unitary rigid multilayer metal foil structure. The forming operation, which simultaneously stretches the second portion and compresses the third portion of the multilayer metal foil preform into the final multilayer metal foil structure, imparts three dimensional rigidity and structural strength to the final formed multilayer metal foil structure, while also maintaining the spaced apart layers and the gaps between the layers in the first portion of the preform. The forming operation also interlocks the layers at an edge portion of the structure preferably by folding, curling or rolling the edge, e.g., forming a cylindrical bead along the edge of the multilayer structure.
The present invention provides a formed metal structure comprising at least three layers of metal sheet, at least two of which layers are metal foil layers having a thickness 0.006 in. (0.15 mm) or less, formed into a three dimensional unitary structure whereby in a portion of the structure the layers have gaps therebetween provided by spacers to hold the layers apart and in a portion of the structure the layers are interlocked and folded together to substantially eliminate gaps between the layers thereby providing the three dimensional structural strength of the final part. The multilayer metal foil structure is three dimensionally formed from a preform of a stack of said metal layers over a mold whereby portions of the layers are shaped under tensile stress and portions of the layers are shaped under compressive conditions to form the metal foil layers into interlocking folds, wrinkles or rolls, while portions of the layers are maintained in spaced apart relationship with gaps between the layers.
This invention provides multilayer metal foil structures which are free standing, three dimensionally stable or rigid structures, which may be assembled or installed as stand-alone products for heat shield or acoustical shield uses, particularly in automotive applications, without the requirement
Fairchild Stephen J.
Ragland Christopher V.
Ragland G. William
Ragland Raymond E.
Remke Matthew S.
ATD Corporation
Burns Doane Swecker & Mathis
Zimmerman John J.
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