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Technical Field
This invention relates ,to cast articles and in particular to forming composite cast articles having
insulating portions intermediate cast portions thereof.

Background Art
In applications such as exhaust manifold applications, it is desirable to provide an insulative
layer so as to reduce the exterior temperature of the manifold to approximately 204°C. or less.
One conventional solution to the problem of
providing such a low exterior temperature has been to utilize a water cooled manifold. This structure, how-ever has the disadvantage of increased cost and maintenance as well as in undesirably cooling the exhaust gases, thus preventing possible use of the thermal
energy of the gases as with associated apparatus.
In one known form of manifold design, formed
and welded sheet metal walls are provided with a formed inner layer of insulation material. In U. S. Patent RE. 28,988 issued to Scheitlin et al, on October 5, 1976 such an exhaust gas manifold is disclosed wherein the insulating material comprises a layer of compressible material interposed between the inner and outer sheet metal sleeves.
U. S. Patent 3,173,451 issued to Slayter, on
March 16,1965 shows a cast manifold with liner wherein the manifold includes a layer of separate, partic- ulate, highly refractory fibers and a refractory, in-

O PI organic binder, with a body of a cast metal bonded to the layer so as to have a portion of the cast metal extend partially into the layer. This structure requires that the binder have a .melting point in excess of the melting point of the metal.
U. S. Patent 3,949,552 issued to Kaneko et al, on April 13, 1976 shows heat insulating castings
adapted for use in parts of the exhaust system of an internal combustion engine as well as to other parts through which hot gases, liquid or powders may flow.
The Kaneko et al castings comprise triple structure castings including a heat and corrosion resistant
metal sheet with a heat insulating refractory material covering a significant portion of the sheet.
A cast metal envelope is formed about the sheet and refractory material so as to sandwich the refractory material therebetween.
U. S. Patent 2,830,343 issued to Shroyer on
April 26,, 1956 discloses a cavityless -casting mold
and method of making the mold wherein the pattern is provided in a mold body which is burnable by the cast metal as it is poured in so as to be replaced by the cast metal in forming the desired casting. Shroyer teaches the use of expanded plastics, such as poly-styrene or polyethylene, as the pattern material.
U. S. Patent 3,991,808 issued to Nieman et al on November 16, 1976 discloses in one form of casting, control of the characteristics of the cast metal by introducing an alloying material into the cast metal as it is poured into the mold. Thus, the alloying, or inoculating, material is maintained at molten form in the casting metal only for a short period of time until the casting metal cools, thereby providing improved reproducible control over the microstructure and final properties of the castings.

A - W1P Disclosure of Invention
The present invention provides an improved
insulative casting composite article and method of
forming the same wherein both .inner and outer cast
portions are formed in situ at opposite sides of an
insulative barrier member whereby the barrier member
serves as a portion of the pattern of the castings and is retained therebetween in the final article.
In the illustrated embodiment, the castings are formed by gasifying an expendable gasifiable pattern juxtaposed to the insulative member with the assembly of the patterns and insulative member being provided in a suitable mold formed of suitable particulate
material, such as sand, etc.
Both the inner and outer portions of the composite article may be cast simultaneously, or they
may be cast independently, as desired. The casting
may be effected from the common source of molten metal where each of the inner and outer .cast portions are to be formed of similar metal.
Where the inner and outer portions are to be
cast of different metals, separate sprues and gates
may be provided as desired.
Where the different metals differ solely in
additive -characteristics , the casting may be effected from a single source of molten metal with the metal
flowing to one or both of the patterns having additive material added thereto as desired during the flow of the metal to the pattern.
The patterns may be preformed of suitable
gasifiable material, and in the illustrated embodiment, each of the patterns is formed of a plurality of
The assembly of the patterns and insulative

O PI portion. may be provided with an outer refractory
coating. The pattern portions may be adhesively
joined prior to the application of the coating.
The castings and insulative portion of the
composite article may be interlocked together to
maintain the desired integrity of the article.
In the illustrated embodiment, the patterns are formed of styrofoam and the refractory coating is an airdried slurry.
The composite article and method of forming the same of the present invention are extremely
simple and economical while yet providing the highly desirable insulative structure as discussed above.

Brief Description of Drawings
The invention will be further described with reference to the drawing, in which:
FIGURE 1 is a perspective view of a composite article embodying the invention;
FIGURE 2 is a fragmentary vertical section of a mold provided with expendable patters and intermediate insulative portions, the inner casting being shewn as upon completion of the casting process and the outer casting being shown as being formed by the delivery of molten metal through the sprue and gate
associated therewith;
FIGURE 3 is a fragmentary section taken substantially along the line 3-3 of Figure 2;
FIGURE 4 is a fragmentary vertical section illustrating the method of forming the composite article wherein a common source of molten metal is utilized to provide the casting material to from both inner and outer casting portions; and

y)y W1P FIGURE 5 is a fragmentary vertical section illustrating a modified method of forming the composite article wherein a common source of molten metal is utilized, but wherein one of the streams is provided with additive material prior to the delivery thereof to one of the patterns .

Best Mode for Carrying Out the Invention
In the exemplary embodiment of the invention as disclosed in the drawing, a composite article gen-erally designated 10 is shown to comprise an inner cast portion, 11, an outer cast portion 12, and an
"'intermediate insulative portion 13. In the article 10, the insulative portion 13 effectively defines the pattern for the outer surface 14 of the inner cast portion 11 and the pattern for the inner surface 15 of the outer cast portion 12. Thus, as shown in
Figure 2 of the drawing, the arrangement is such that the cast portions are interlocked together automatically with the insulative portion 13 locked in facial engagement with each of the inner and outer cast portions to define an effectively laminated insulated casting.
As shown in Figure 2 , the patterns for forming the composite cast article may include an inner ex- pendable gasifiable pattern 16 and outer expendable gasifiable pattern 17. As shown in Figure 3, the patterns and insulative portion are snugly assembled and may be formed in a plurality of separate parts joined by suitable interlocking portions 18 which may be adhesively secured as desired. Thus, the outer surface 19 of the inner pattern 16 is facially juxtaposed to the inner surface 20 of the insulative layer 13 and the outer surface 21 of the insulative layer is facially juxtaposed to the inner surface 22 of the outer pattern 17.

Upon completion of the assembly, including the gating portion 23, such as illustrated in Figure 2, the entire assembly may be coated with a suitable refractory slurry which may be, airdried to form a thin refractory coating 24 on the assembly.
The coated assembly may then be placed in a suitable mold box and surrounded with a flowable mold material, such as sand or metal shot, adapted to flow under vibration to provide a high density,
uniform particulate mold 32 about the assembly, as shown in Figure 2. As shown, the top of the gate portion 23 at 25 and 26 may define entrance portions into which casting metal 27 may be poured from .a suitable crucible 28, in the conventional manner.
In the embodiment of Figure 2, a dam 29 may be provided to separate the gate 23 into a first portion 23a for delivering cast metal to the outer pattern 17 a a second portion 23b for delivering the motel metal to the inner pattern 16. In the illustration of Figure 2, the casting process relative to the inner portion of the casting has been completed with the cast metal 27 extending throughout the pattern space. In effecting such casting, the incoming molten casting metal gasifies the gate and pattern material so as to drive it into the surrounding mold sand, or other particulate material, as described in the above-mentioned Shroyer patent 2,830,343. The gasifying of the expendable pattern material, such as in the gate portion 23a, is illustrated in Figure 2 adjacent the upper gate portion 25.
In the illustrated embodiment, the pattern and gate material may be formed of the same material, and illustratively may comprise styrpfoam. The styrofoam may be accurately formed into the desired pattern confifguration and, thus, offers a low cost, accurate ethod of providing the desired- manifold cast portions .
Upon completion of the casting of both metal portions of the composite article and cooling thereof, the mold box may be broken open and the mold particulate material removed, permitting the gate portions to be removed from the article in the conventional
manner, thereby completing the forming of the article, as shown in Figure 1. As a result of the configuration of the article, the cast portions are intermittently interlocked with the insulative portion to provide a permanent, unitary assembly.
As indicated briefly above, where the metal
forming both the inner and outer cast portions of the article is similar, the gate may be provided with a single inlet portion, such as inlet portion 125 of
gate portion 123, illustrated in Figure 4.
Further, as illustrated in Figure 5, the pouring of the molten metal to both the inner and outer patterns may be effected simultaneously. Where the metal of one of the portions is to differ from that of the other portion as by the inclusion of additives or alloying material, such additives or alloying material may be added to the stream 130 of the molten metal 27 as it is flowing inwardly through gate 126 from a
common source 128. Thus, in the embodiment of Figure 5, the inner and outer cast portions are effectively formed of metals having different characteristics while yet being formed simultaneously from a common supply of casting metal. As will be obvious to those skilled in the art, different additives may be provided to each of the streams 130 and 131 if desired.
The embodiments of Figures 4 and 5 are similar to that of the embodiment of Figures 1-3 in all other respects.

OMPI The material of which the insulative portion is formed and the thickness thereof may be suitably preselected to provide the desired temperature
recucing effect.
The foregoing disclosure of specific embodiments is illustrative of the broad inventive concepts comprehended by the invention.

Ay W1