U.S. patent application number 14/610169 was filed with the patent office on 2016-08-04 for bondcasting process using investment and sand casting.
The applicant listed for this patent is United Technologies Corpoation. Invention is credited to Mark A. White.
Application Number | 20160221077 14/610169 |
Document ID | / |
Family ID | 55272308 |
Filed Date | 2016-08-04 |
United States Patent
Application |
20160221077 |
Kind Code |
A1 |
White; Mark A. |
August 4, 2016 |
BONDCASTING PROCESS USING INVESTMENT AND SAND CASTING
Abstract
A method of forming a component having a plurality of parts
constructed from at least two different materials includes forming
a first part made from a first material, placing a sandcasting
pattern in a sand molding box, filling the sand molding box with
sand, removing the sandcasting pattern from the sand molding box,
placing the first part in a first portion of a void in the sand
with the void formed by the removal of the sandcasting pattern,
filling a remaining area of the void with a second material, and
allowing the second material to solidify to form a second part.
Inventors: |
White; Mark A.; (Palm City,
FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United Technologies Corpoation |
Hartford |
CT |
US |
|
|
Family ID: |
55272308 |
Appl. No.: |
14/610169 |
Filed: |
January 30, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22D 19/04 20130101;
B22D 19/02 20130101; B22C 9/02 20130101 |
International
Class: |
B22D 19/04 20060101
B22D019/04; B22C 9/02 20060101 B22C009/02 |
Claims
1. A method of manufacturing an apparatus comprising: providing a
first sub-component having a locking feature, the first
sub-component being constructed from a superalloy; placing the
first sub-component into a void in sand in a sand molding box, the
void having a first portion shaped like the first sub-component and
a second portion shaped like a second sub-component with the first
sub-component sitting in the void such that the locking feature is
adjoining the second portion and the second portion is unoccupied
by the first sub-component; introducing a second material in a
fluidic state into the second portion so that the second material
is adjacent to at least a part of the locking feature; and
solidifying the second material to form the second sub-component
adjoining the locking feature.
2. The method of claim 1, the step of placing the first
sub-component into the void in the sand casting mold comprising:
molding part of the first portion of the void and part of the
second portion of the void in a first sand molding box through the
use of a first pattern; placing at least a part of the first
sub-component into the part of the first portion of the void;
molding a remaining part of the first portion of the void and a
remaining part of the second portion of the void in a second sand
molding box through the use of a second pattern; and placing the
second sand molding box adjacent to the first sand molding box.
3. The method of claim 2, wherein the part of the first portion in
the first sand molding box and the remaining part of the first
portion in the second sand molding box form the void that has the
same dimensions as the first sub-component such that when at least
a part of the first sub-component is placed into the part of the
first portion of the first half of the sand molding box the sand in
the first half of the sand molding box is undisturbed and when the
remaining part of the first portion in the second half of the sand
molding box is placed adjacent to the first half of the sand
molding box the sand in the second half of the sand molding box is
undisturbed.
4. The method of claim 1, wherein the first sub-component is made
up of a plurality of pieces with each piece being similarly shaped
and unattached to other pieces of the first component.
5. The method of claim 4, further comprising: aligning the
plurality of pieces in the first portion of the void.
6. The method of claim 4, wherein the second sub-component has an
annular shape and the plurality of pieces of the first
sub-component are arranged radially within the second
sub-component.
7. The method of claim 1, wherein the locking feature is a
projection that extends into the second portion such that the
second sub-component solidifies around the locking feature.
8. The method of claim 1, wherein the first sub-component includes
at least one hollow feature.
9. The method of claim 1, wherein the melting temperature of the
first material is higher than the melting temperature of the second
material.
10. The method of claim 1, wherein the first component is
constructed using investment casting.
11. The method of claim 1, further comprising: performing final
finishing on the first sub-component and the second
sub-component.
12. A method of making an apparatus constructed from at least two
different materials, the method comprising: investment casting a
first sub-component constructed from a first material, the first
sub-component having a locking feature; placing a first pattern in
sand to create a first sand casting mold; placing a second pattern
in sand to create a second sand casting mold; removing the first
pattern and the second pattern; positioning the first sub-component
in a first impression in the first sand casting mold, the first
impression being sized to house at least a portion of the first
sub-component, the first sub-component being positioned so that the
locking feature is adjoining a second impression in the first sand
casting mold that has the same dimensions as at least a portion of
a second sub-component; assembling the first sand casting mold and
the second sand casting mold so that the first sub-component is
within a first cavity having the same dimensions as the first
sub-component and a second cavity having the same dimensions as the
second sub-component is formed adjacent to the locking feature;
introducing a second material in a fluidic state into the second
cavity to form the second sub-component; and allowing the second
material to solidify within the second cavity adjoining the locking
feature.
13. The method of claim 12, further comprising: removing the first
sand casting mold and the second sand casting mold from around the
first sub-component and the second sub-component.
14. The method of claim 12, wherein the second sub-component
solidifies around the locking feature.
15. The method of claim 12, wherein the first sub-component
includes at least one hollow feature.
16. A method of forming a component having a plurality of parts
constructed from at least two different materials, the method
comprising: forming a first part made from a first material;
placing a sandcasting pattern in a sand molding box; filling the
sand molding box with sand; removing the sandcasting pattern from
the sand molding box; placing the first part in a first portion of
a void in the sand, the void formed by the removal of the
sandcasting pattern; filling a remaining area of the void with a
second material; and allowing the second material to solidify to
form a second part.
17. The method of claim 11, further comprising: forming a third
part made from a third material; and placing the third part in a
second portion of the void in the sand.
18. The method of claim 17, wherein the first part and the third
part are formed using investment casting.
19. The method of claim 16, wherein the first part is a plurality
of similarly shaped pieces.
20. The method of claim 16, wherein the first part is made from a
high temperature alloy.
Description
BACKGROUND
[0001] The present disclosure relates to a method of manufacturing
and, more particularly, a method of casting an apparatus
constructed from at least two, but possibly many, different
materials.
[0002] It is desirable to form complex apparatuses from multiple
materials where unique properties of one material are needed in one
area of the finished apparatus while unique properties of another
material are needed in another area of the finished apparatus. When
multiple materials are needed, combining these sub-components into
one final finished apparatus becomes troublesome. The
sub-components can be manufactured separately and fastened to one
another through rivets, bolts, or welds, but that requires
additional manufacturing steps that are time consuming and
inefficient. Another process includes manufacturing the
sub-components made from one material and then investment casting
or die casting other sub-components made from a different material
around the first sub-components. This process is only applicable
when the first sub-components are made from a material that can
withstand investment or die casting without melting or becoming
damaged or when the second sub-component has a configuration suited
for investment or die casting (the sub-component is not too large
and/or does not have features that cannot be investment or die
casted). Additionally, the investment or die casting processes may
need to be altered to accommodate the inclusion of the first
sub-components that are not being investment or die casted.
[0003] Therefore, there is a need for a process of forming a
finished apparatus made from multiple materials that is more
efficient and less time consuming.
SUMMARY
[0004] A method of manufacturing an apparatus includes forming a
first sub-component having a locking feature with the first
sub-component being constructed from a superalloy (or another high
temperature alloy), placing the first sub-component into a void in
sand in a sand molding box with the void having a first portion
shaped like the first sub-component and a second portion shaped
like a second sub-component and the first sub-component sitting in
the void such that the locking feature is adjoining the second
portion and the second portion is unoccupied by the first
sub-component, introducing a second material in a fluidic state
into the second portion so that the second material is adjacent to
at least a part of the locking feature, and allowing the second
material to solidify to form the second sub-component adjoining the
locking feature.
[0005] A method of making an apparatus constructed from at least
two different materials includes investment casting a first
sub-component constructed from a first material with the first
sub-component having a locking feature, placing a first pattern in
sand to create a first sand casting mold, placing a second pattern
in sand to create a second sand casting mold, removing the first
pattern and the second pattern, positioning the first sub-component
in a first impression in the first sand casting mold with the first
impression being sized to house at least a portion of the first
sub-component and the first sub-component being positioned so that
the locking feature is adjoining a second impression in the first
sand casting mold that has the same dimensions as at least a
portion of a second sub-component, assembling the first sand
casting mold and the second sand casting mold so that the first
sub-component is within a first cavity having the same dimensions
as the first sub-component and a second cavity having the same
dimensions as the second sub-component is formed adjacent to the
locking feature, introducing a second material in a fluidic state
into the second cavity to form the second sub-component, and
solidifying the second material within the second cavity adjoining
the locking feature.
[0006] A method of forming a component having a plurality of parts
constructed from at least two different materials includes forming
a first part made from a first material, placing a sandcasting
pattern in a sand molding box, filling the sand molding box with
sand, removing the sandcasting pattern from the sand molding box,
placing the first part in a first portion of a void in the sand
with the void formed by the removal of the sandcasting pattern,
filling a remaining area of the void with a second material, and
allowing the second material to solidify to form a second part.
[0007] The present summary is provided only by way of example and
not limitation. Other aspects of the present disclosure will be
appreciated in view of the entirety of the present disclosure,
including the entire text, claims, and accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a flow chart of a bondcasting process.
[0009] FIG. 2A is a cross-section of a portion of a mold used in
the bondcasting process.
[0010] FIG. 2B is a cross-section of the mold in FIG. 2A with a
portion of a first sub-component of an apparatus.
[0011] FIG. 2C is a cross-section of a portion of the finished
apparatus constructed through use of the mold in FIG. 2A.
[0012] FIG. 3 is a cross-section of a portion of a finished
apparatus constructed through the bondcasting process having
another embodiment of a locking feature.
[0013] FIG. 4 is a cross-section of a portion of a finished
apparatus constructed through the bondcasting process having yet
another embodiment of a locking feature.
[0014] FIG. 5A is a cross-section of a portion of a turbine exhaust
case constructed through the bondcasting process.
[0015] FIG. 5B is a cross-section of a portion of the turbine
exhaust case of FIG. 3A taken along section line B-B.
[0016] While the above-identified figures set forth embodiments of
the present disclosure, other embodiments are also contemplated, as
noted in the discussion. In all cases, this disclosure presents the
invention by way of representation and not limitation. It should be
understood that numerous other modifications and embodiments can be
devised by those skilled in the art, which fall within the scope
and spirit of the principles of the invention. The figures may not
be drawn to scale, and applications and embodiments of the present
invention may include features, components, and steps not
specifically shown in the drawings.
DETAILED DESCRIPTION
[0017] A method entitled "bondcasting" is disclosed herein that can
include elements of the investment casting process and the sand
casting process and introduces new elements to cast a finished
apparatus that has sub-components constructed from multiple
materials. The bondcasting process does not require the
sub-components to be welded, riveted, bolted, or otherwise fastened
to one another after the bondcasting process is complete because
the sub-components are locked together through mechanical
engagements (the geometry of the sub-components holds the
sub-components stationary relative to one another). The bondcasting
process can be performed even if a sub-component is constructed
from a material that has a relatively high melting point, like a
superalloy (such as a nickel based superalloy), and/or if a
sub-component requires hollow features or an opening within the
sub-component. The bondcasting process can also be performed even
if a sub-component is too large to be efficiently constructed
through another casting process, such as die casting. Additionally,
the bondcasting process is flexible and allows for easy adjustment
to produce sub-components that are closer to the desired
configuration because the pattern and molds used to make the
finished apparatus can be formed and altered more easily than other
processes. This flexibility is important when multiple
sub-components are being constructed together to form a finished
apparatus.
[0018] While the bondcasting process described below discusses a
summary of the investment casting process (which occurs before the
steps of the sand casting sub-process of the bondcasting process),
some steps of the investment casting process can be added or
omitted. Additionally, the sub-component does not need to be
constructed through the investment casting process and can be
constructed through another process, such as forging. Likewise,
while the bondcasting process described below discusses a version
of the sand casting process with modifications and additions, some
steps of the sand casting process can be added or omitted.
[0019] FIG. 1 is a flow chart of an embodiment of a bondcasting
process. Bondcasting process 10 is separated into investment
casting sub-process 12, which includes some steps that are related
to the industry-known investment casting process, and sand casting
sub-process 14, which includes some steps that are related to the
industry-known sand casting process. Both investment casting
sub-process 12 and sand casting sub-process 14 have additional
and/or modified steps that accommodate bondcasting process 10 and
distinguish bondcasting process 10 from known processes. Also,
bondcasting process 10 can omit investment casting sub-process 12
and instead include another sub-process used to construct a first
sub-component (known as the investment cast sub-component
below).
[0020] Investment casting sub-process 12 of bondcasting process 10
includes the steps of forming the investment 20, removing the wax
pattern from the investment 22, introducing the investment casting
material into the investment 24, and removing the investment
26.
[0021] Sand casting sub-process 14 of bondcasting process 10
includes placing the pattern into the molding boxes 30, filling the
molding boxes with sand 32, removing the pattern to form the molds
34, placing the investment cast sub-component in the mold 36,
aligning the investment cast sub-component 38, combining the
molding boxes to create a complete mold 40, introducing the sand
casting material into the mold 42, solidifying the sand cast
sub-component 44, removing the molding boxes and molds 46, and
performing the final finishing 48.
[0022] Investment casting sub-process 12 can begin by forming the
investment 20. To form the investment 20, a wax pattern can be
constructed (through the use of a master pattern and/or master
die). Then the wax pattern is encapsulated with the investment,
which can include coating the wax pattern with slurry, stuccoing
(covering) the coating/wax pattern with a powder/particulate
(usually a ceramic based particulate), and hardening the
coating/stucco. The coating/stucco should completely and fully
encapsulate the wax pattern so that the coating/stucco has the same
inner geometry as an outer geometry of the wax pattern (the
coating/stucco is the negative of the dimensions of the wax
pattern). These steps can be repeated as needed to arrive at an
investment (which is the coating/stucco shell) that is sufficiently
thick and structurally supportive to withstand the remaining steps
of investment casting sub-process 12.
[0023] Removing the wax pattern from the investment 22 is then
executed. During this process, the wax pattern is melted and/or
vaporized to remove it from within the investment. The method used
to remove the wax pattern from the investment depends on the
material used to create the wax pattern and the resiliency of the
investment, but removal of the wax pattern should be done in such a
way so as to not disturb the inner geometry of the investment.
[0024] Introducing the investment casting material into the
investment 24 is usually performed by pouring an investment casting
material, which is the material used to make the desired
sub-component (known as the investment cast sub-component), into a
void in the investment that was previously occupied by the wax
pattern. To pour the investment casting material into the void in
the investment, the investment casting material should be in a
fluidic state, likely at an elevated temperature. The investment
casting material can be a variety of materials, including a
metallic material, a superalloy (such as a nickel based
superalloy), or any other desired material that is able to be
melted, poured into the investment, and hardened to form the
investment cast sub-component. The temperature needed to
liquefy/melt the casting material can govern the materials used to
make the investment, for the investment must be suited to handle
the elevated temperature of the investment casting material and the
stresses incurred during the cooling of the investment casting
material. After the investment casting material is within the
investment, the investment casting material is cooled so that it
hardens into a solid in the shape of the previously removed wax
pattern (the solid is known as the investment cast
sub-component).
[0025] Once the investment cast sub-component has hardened,
removing the investment 26 separates the investment (the hardened
coating/stucco) from the investment cast sub-component. The
investment can be removed through hammering, blasting, vibrating,
water-jetting, chemical dissolving, and/or other processes. Removal
of the investment results in the investment cast sub-component
remaining without the investment (the coating/stucco shell).
Depending on the configuration of the investment cast
sub-component, final finishing, such as grinding, can be performed
as desired to arrive at the final finished investment cast
sub-component. The final design of the total component (the
finished apparatus made through bondcasting process 10, which
includes the sub-component made through investment casting
sub-process 12 along with the sub-component made through sand
casting sub-process 14) may call for multiple investment cast
sub-components. If multiple investment cast sub-components are
required, the multiple pieces can go through investment casting
sub-process 12 together by being attached to a common structural
support (known as a tree), put through the investment process
together, and separated after the investment has been removed.
[0026] As mentioned above, investment casting sub-process 12 can be
used to construct a sub-component from a material that has a
relatively high melting point, like a superalloy (such as a nickel
based superalloy). Investment casting sub-process 12 is also used
when the investment cast sub-component requires hollow features or
an opening within the investment cast sub-component. Additionally,
investment casting sub-process 12 is used to preserve the chemical
and physical properties of the investment casting material to
arrive at a material composition that exhibits desired
characteristics, such as desired metallic grain structure (e.g.,
single crystal grain structure). As discussed below with regards to
sand casting sub-process 14 of bondcasting process 10, the
investment cast sub-component (or multiple sub-components) is
incorporated into sand casting sub-process 14 to create a finished
apparatus constructed from more than one material.
[0027] Bondcasting process 10 can omit investment casting
sub-process 12 and can instead include another sub-process, such as
forging or permanent mold casting, to form the sub-component that
will be inserted into the mold during sand casting sub-process 14.
Also, multiple sub-components that will be inserted into the mold
during sand casting sub-process 14 can be formed through different
sub-processes, such as one sub-component made through investment
casting sub-process 12 and another sub-component made through
forging, permanent mold casting, or another sub-process. Thus, when
discussing sand casting sub-process 14 or the embodiments in FIGS.
2A-5B below, the investment cast component can be formed through
another sub-process.
[0028] During sand casting sub-process 14 of bondcasting process
10, the first step is placing the pattern into the molding boxes
30. In this step, a pattern, which is a replica of the finished
apparatus having the same dimensions as the finished apparatus, is
placed into a molding box. The pattern is shaped such that when
sand is filled around the pattern and the pattern is removed, a
void is left behind that is a replica of the finished apparatus.
The various methods for constructing the pattern are known in the
industry and include the use of a master die and/or etching or
machining the pattern directly into a form. The pattern can be two
pieces, known as the cope and the drag, that each include a portion
of the replica having the same dimensions as part of both the
investment cast sub-component and the sand cast sub-component (the
two patterns are used in a first sand molding box and a second sand
molding box and the two sand molding boxes and then brought
together). The pattern can be made from a variety of materials,
including wood, plastic, metal, or another material. Aside from the
portion of the pattern that is the replica of the finished part,
each pattern also includes planar extending surfaces that, when
combined with the molding boxes (discussed below), create a
box-like structure that is able to hold sand to create the mold.
The portion of the pattern that is the replica of the finished
apparatus may need to be configured to form a void that is slightly
larger than the desired finished apparatus to account for
contraction of the sand casting material during
solidification/cooling (the pattern may need to have slightly
larger dimensions than the finished apparatus). Because only the
sand casting material may contract during sand casting sub-process
14, it may be necessary only for the void that will be filled with
the sand casting material to be enlarged. Each pattern is placed
into a corresponding molding box, which usually has four sides
forming a rectangle. The pattern attaches to the four sides and
forms a fifth side which, together with the four sides, creates a
box into which sand may be introduced and contained to create the
mold. The pattern is attached to the four sides in such a manner
that the portion of the replica of the finished apparatus extends
into the sand molding box. Generally there are two molding boxes,
but other configurations can have just one molding box or more than
one molding box.
[0029] Once the molding boxes have been assembled, filling the
molding boxes with sand 32 is performed to create the mold. With
each of the two patterns forming one side of each of the molding
boxes (the first molding box and the second molding box), the
molding boxes are completely filled with sand and packed so that
when the patterns are removed, an indent remains in each of the
sand-filled molding boxes that has a portion of the same dimensions
as the finished apparatus such that when the first molding box and
second molding box are combined, the indent forms a void with the
same dimensions as the finished apparatus. As discussed in the next
step, the packed sand with the indent caused by the pattern is
known as the mold.
[0030] The "sand" used to fill the molding boxes to create the
molds does not necessarily have to be pure silica or calcium
carbonate sand, for "sand" is an industry term of art. The sand
material can be a variety of materials and/or mixtures, such as a
mixture that includes silica sand, chromite sand, zircon sand,
olivine, staurolite, graphite, bentonite (clay), water, inert
sludge, anthracite, adhesive, binders, oil, resin, cushioning
material, reducing agents, iron oxide powder, sodium silicate,
synthetic sand, or other materials. The sand should collectively
form a substance that can completely form to the shape of the
pattern and sustain that shape after the pattern has been removed
from the molding boxes and while the void in the mold is filled
with the investment cast sub-component and the sand casting
material. After the molding boxes are filled with sand, the sand
can be left to harden or may undergo further treatment to ensure
the sand hardens (such as heating).
[0031] Then, removing the patterns from the molding boxes 34 is
executed. The patterns are each removed from the molding boxes so
that the molding boxes are left behind and a mold (the remaining
formed sand structure) is formed in the sand in each molding box
with each mold having a void (the indent left in the mold by the
pattern). The molds should be a negative replica of the finished
apparatus such that the voids formed by each of the molds should
have the same dimensions as a portion of the finished apparatus
such that when the molds are brought together the void formed has
the same dimensions as the finished apparatus.
[0032] Because the patterns can be made from a variety of materials
that are easily manipulated; such as wood, plastic, plaster, and
others; and the molds are made from sand or another material that
is easily formed, the patterns and molds can be easily adjusted if
the finished apparatus needs to have a different configuration than
what was intended in the original design. Therefore, bondcasting
process 10 is flexible and allows for adjustment on the fly (i.e.,
after bondcasting process 10 has begun) without the need to scrap
the partially-constructed cub-components, which increases
efficiency and reduces time and cost.
[0033] After the patterns are removed to form the molds in the sand
and leave behind the void having the same dimensions as the
finished apparatus, placing the investment cast sub-component in
the mold 36 is performed. The investment cast sub-component is
placed in one of the molds (to fill at least a portion of the void)
in one of the molding boxes, for the two molding boxes are separate
from one another up until a subsequent step (when the first sand
molding box and the second sand molding box are combined). Here,
the investment cast sub-component is positioned in the void in one
mold, which has a portion of the same shape as the investment cast
sub-component and the sand cast sub-component. The void should be
sized so the mold in the molding boxes is not disturbed (the sand
does not shift) by the placement of the investment cast
sub-component, and the sand should provide sufficient support in
the mold to support the investment cast sub-component.
[0034] Next, aligning the investment cast sub-component in the mold
38 is performed. A number of different pieces, including multiple
investment cast sub-components, can be placed in the void, with the
different investment cast sub-components being carefully aligned in
the void to produce a finished apparatus with multiple investment
cast sub-components adjoining the sand cast sub-component (as shown
in FIG. 5A). As described further below, one or more of the
investment cast sub-components can include one or multiple locking
features having a variety of configurations, such as projections,
grooves, or other configurations (shown in FIGS. 2C, 3, 4, 5A, and
5B) that adjoin or extend outward into a remaining portion of the
void (the portion not filled by the investment cast
sub-component(s)) so that when the sand casting material is
introduced into the remaining portion of the void and solidifies,
the locking feature and the sand cast sub-component form a
mechanical engagement that prevents movement of the investment cast
sub-component relative to the sand cast sub-component. Depending on
the configuration of the sand cast sub-component, other features
can be aligned in the remaining portion of the void, such as cores,
which are features that are used to produce cavities in the sand
cast sub-component. These features are then removed after the sand
cast sub-component solidifies to leave behind cavities in the sand
cast sub-component.
[0035] With the investment cast sub-component on the mold (in the
void) in one of the molding boxes, combining the molding boxes to
create a complete mold 40 is performed to create a fully enclosed
void that has the same dimensions as the sand cast sub-component.
Combining the molding boxes to create a complete mold 40 should be
done with care so that the mold and the void are not disturbed (the
sand does not shift). The remaining portion of the void can be
adjoining the investment cast sub-component and can have within it
one or multiple locking features and/or other features (as
discussed above). The sand should be structurally sufficient to
allow for movement and combining of the molding boxes without the
sand shifting and altering the molds.
[0036] Introducing the sand casting material into the mold 42 is
performed to create the sand cast sub-component having the same
shape as the remaining portion of the void formed by the complete
mold (the combination of the mold in the first sand molding box and
the mold in the second sand molding box). The sand casting material
can be introduced into the void through a hole in the sand that
extends from the surface of the molding box to the void. The sand
casting material used to fill the void can be a variety of
materials, such as metal, an alloy, a plastic, or a resin. The
material can have a melting point equal to or less than the melting
point of the investment cast sub-component to ensure that the
investment cast sub-component does not melt when the high
temperature liquefied/molten sand casting material is introduced
into the void adjoining the investment cast sub-component. If the
temperature of the sand casting material is close to the melting
point of the investment cast sub-component when it is introduced
into the void, a metallurgical or semi-metallurgical bond can form
between the investment cast sub-component and the sand cast
sub-component due to partial or complete melting of the surface of
the investment cast sub-component adjoining the sand cast
sub-component (in additional to a mechanical engagement). If the
temperature of the sand casting material is significantly less than
the melting point of the investment cast sub-component when it is
introduced into the void, no melting of the investment cast
sub-component will result and only a mechanical engagement (due to
the locking feature) is formed.
[0037] After the sand casting material is introduced into the mold
and in place in the void, solidifying the sand cast sub-component
44 ensures that the sand casting material takes the shape of the
remaining void to form the desired configuration of the finished
apparatus. The sand cast sub-component can be allowed to solidify
on its own, or various measures can be taken to ensure the sand
casting material of the sand cast sub-component solidifies properly
to preserve the chemical and physical properties of the sand cast
sub-component. If the investment cast sub-component has a locking
feature (or multiple locking features), the sand casting material
is allowed to solidify adjacent to the locking feature such that
the configuration of the solidified sand cast sub-component and the
locking feature form a bond that prevents the sand cast
sub-component and the investment cast sub-component from moving
relative to one another. The mechanical engagement formed between
the locking feature and the sand cast sub-component is a result of
the geometry of both, which prevents the two from moving relative
to one another.
[0038] Once the sand cast sub-component has solidified, removing
the molds and molding boxes 44 is performed. With the sand cast
sub-component solidified and in place adjacent to the investment
cast sub-component, the molds, which are constructed from sand, and
the molding boxes are separated from the finished apparatus.
Usually, the molding boxes can be separated from the sand, molds,
and finished apparatus without much difficulty. Depending on the
composition of the sand, various means of removing the sand can be
used, including hammering, blasting, vibrating, water-jetting,
chemical dissolving, and/or other processes.
[0039] After the sand is removed, performing the final finishing 46
is done, if needed, on the finished apparatus (which includes the
investment cast sub-component and the sand cast sub-component) to
remove any imperfections. The final finishing can be done through
grinding or another process, such as cleaning the finished
apparatus with a chemical solution.
[0040] As mentioned above, bondcasting process 10 results in a
finished apparatus that has multiple sub-components made from
different materials. Bondcasting process 10 enables the
construction of a finished apparatus having materials that are not
able to be incorporated into a finished apparatus through another
process without the need for costly and time consuming fabrication
through welding, bolting, or otherwise fastening the sub-components
together. The differing sub-components, referred to above as the
investment cast sub-component(s) and the sand cast sub-component,
can be secured to one another through one or multiple locking
features. The locking feature can have a variety of configurations,
with some nonlimiting embodiments provided in FIGS. 2C, 3, and
4.
[0041] FIG. 2A is a cross-section of a portion of molds 50 used in
bondcasting process 10, FIG. 2B is a cross-section of the portion
of molds 50 with a first sub-component of a finished apparatus, and
FIG. 2C is a cross-section of finished apparatus 59 constructed
through the use of molds 50 in FIG. 2A.
[0042] FIG. 2A shows a portion of molds 50 (first mold 50A and
second mold 50B) having void 53 with first portion 52 (which will
house the investment cast sub-component) and second portion 54
(which will house the sand cast sub-component). As shown in the
illustrated embodiment, first mold 50A and second mold 50B each
have a part of first portion 52 and second portion 54, which is
formed by the two patterns discussed in bondcasting process 10
above. After the two patterns (not shown) are removed, first mold
50A and second mold 50B remain behind, with first mold 50A within
the first sand molding box (not shown) and second mold 50B within
second sand molding box (not shown). While FIG. 2A shows first mold
50A adjacent to second mold 50B (to show void 53), the two molds
would not be adjacent to one another until combining the molding
boxes to create the molds 40, which is after the investment cast
sub-component is placed in first portion 52, which is shown in FIG.
2B.
[0043] FIG. 2B shows a portion of molds 50 (first mold 50A and
second mold 50B) having void 53 with investment cast sub-component
62 (within first portion 52, hidden by investment cast
sub-component 62) and second portion 54. Investment cast
sub-component 62 includes locking feature 64 (with projection 64A
and end 64B) and hollow feature 66. Investment cast sub-component
62 will be described in greater detail in regards to FIG. 2C. FIG.
2B shows investment cast sub-component 62 within first portion 52
of void 53, with locking feature 64 extending into second portion
54. First portion 52 should have a similar shape as investment cast
sub-component 62 so that molds 50 are not disturbed when investment
cast sub-component 62 is placed within first portion 52 during
bondcasting process 10.
[0044] FIG. 2C includes finished apparatus 59 having sand cast
sub-component 60 and investment cast sub-component 62. Investment
cast sub-component 62 has locking feature 64 (with projection 64A
and end 64B) and hollow feature 66.
[0045] Investment cast sub-component 62 is formed through
investment casting sub-process 12 of bondcasting process 10 and is
configured to include locking feature 64 having projection 64A,
which extends away from the body of investment cast sub-component
62, and end 64B, which extends away from projection 64A and
provides an extension around which sand cast sub-component 60 can
solidify to hold sand cast sub-component 60 and investment cast
sub-component 62 stationary relative to one another. During
bondcasting process 10, investment cast sub-component 62 is placed
and then aligned within the mold such that locking feature 64
extends into second portion 54 of void 53, which is then filled
with the second casting material to form sand cast sub-component 60
around end 64B, producing a mechanical engagement. As shown in
FIGS. 2A and 2B, sand would be in place in the space between sand
cast sub-component 60 and investment cast sub-component 62 during
some of the steps of sand casting sub-process 14 of bondcasting
process 10 to ensure that finished apparatus 59, as seen in FIG.
2C, includes such a space. As mentioned above, the temperature of
the sand casting material when introduced into second portion 54 of
void 53 can be varied to cause the surface of locking feature 64 to
melt such that when sand cast sub-component 60 and locking feature
64 solidify, a metallurgical or semi-metallurgical bond forms along
with the mechanical engagement. While FIG. 2C shows locking feature
64 as a generally T shape, locking feature 64 can have other
configurations as desired for particular embodiments. Investment
cast sub-component 62 also has hollow feature 66, which is an
opening that allows air, another fluid, or another part to go
therein. Creation of hollow feature 66 in investment cast
sub-component 62 would be difficult through the use of another
process, such as die casting, but is a common practice in the
investment casting process and can be accommodated in bondcasting
process 10.
[0046] FIG. 3 is a cross-section of a finished apparatus
constructed through bondcasting process 10 having another
embodiment of a locking feature. FIG. 3 includes finished apparatus
159 having sand cast sub-component 160 and investment cast
sub-component 162. Investment cast sub-component 162 has locking
feature 164.
[0047] Investment cast sub-component 162 is formed through
investment casting sub-process 12 of bondcasting process 10 and is
configured to include locking feature 164, which is a groove into
which sand cast sub-component 160 can extend (into which the
liquefied sand casting material can flow and eventually solidify).
Locking feature 164 can have a dovetail configuration in which the
sides of locking feature 164 angle inward to prevent sand cast
sub-component 160 from becoming separated from investment cast
sub-component 162. During bondcasting process 10, investment cast
sub-component 162 is placed and aligned within the mold such that
investment cast sub-component 162 and locking feature 164 are
adjacent to a void which is then filled with the second casting
material to form sand cast sub-component 160. Sand cast
sub-component 160 then solidifies adjacent to and within locking
feature 164, producing a mechanical engagement. As mentioned above,
the temperature of the sand casting material when introduced into
the void can be varied to cause the surface of investment cast
sub-component 162 to melt such that when second cast sub-component
160 and the surface of investment cast sub-component 162 solidify,
a metallurgical or semi-metallurgical bond forms along with the
mechanical engagement. While FIG. 3 shows locking feature 64 as one
groove, locking feature 64 can have other configurations, such as
multiple grooves or holes.
[0048] FIG. 4 is a cross-section of a finished apparatus
constructed through bondcasting process 10 having a third
embodiment of a locking feature. FIG. 4 includes finished apparatus
259 having sand cast sub-component 260 and investment cast
sub-component 262. Investment cast sub-component 262 has locking
feature 264.
[0049] Investment cast sub-component 262 is formed through
investment casting sub-process 12 of bondcasting process 10 and is
configured to include locking feature 264, which is a relatively
wide projection that extends away from the body of investment cast
sub-component 262 to provide an extension around which sand cast
sub-component 260 can solidify to hold sand cast sub-component 260
and investment cast sub-component 262 stationary relative to one
another. During bondcasting process 10, investment cast
sub-component 262 is placed and aligned within the mold such that
locking feature 264 extends into a void which is then filled with
the second casting material to form sand cast sub-component 260
around locking feature 264, producing a mechanical engagement. In
this configuration, sand would be in place in the space between
sand cast sub-component 260 and investment cast sub-component 262
during some of the steps of sand casting sub-process 14 of
bondcasting process 10 to ensure that finished apparatus 259
includes such a space. As mentioned above, the temperature of the
sand casting material when introduced into the void can be varied
to cause the surface of locking feature 264 to melt such that when
second cast sub-component 260 and locking feature 264 solidify, a
metallurgical or semi-metallurgical bond forms along with the
mechanical engagement. While FIG. 4 shows locking feature 64 as a
generally dovetail shaped projection, locking feature 64 can have
other configurations.
[0050] FIG. 5A is a cross-section of a portion of a turbine exhaust
case constructed through bondcasting process 10, while FIG. 5B is a
cross-section of a portion of the turbine exhaust case of FIG. 3A
taken along section line B-B. Turbine exhaust case 359 includes
first sand cast sub-component 360, a plurality of investment cast
sub-components 362 (with each investment cast sub-component 362
having a plurality of locking features 364), and second sand cast
sub-component 368.
[0051] Turbine exhaust case 359 is an exemplary embodiment of a
device that can be constructed through bondcasting process 10. To
constructed turbine exhaust case 359, first the six investment cast
sub-components 362 are made through investment casting sub-process
12. The six investment cast sub-components 362 are similar in shape
and size and can be made at the same time (going through investment
casting sub-process 12 together by being attached to a tree) or can
be made independently by going through investment casting
sub-process 12 individually. Because FIG. 5A shows a cross-section
of turbine exhaust case 359, the hollow features within each
investment cast sub-component 362 are not shown even though each
investment cast sub-component 362 includes at least one hollow
feature. Also, while FIG. 5A shows a finished apparatus that
includes six investment cast sub-components 362, bondcasting
process 10 can be used to construct a finished apparatus with more
investment cast sub-components 362.
[0052] After the six investment cast sub-components 362 have been
constructed, sand casting sub-process 14 of bondcasting process 10
is performed with a pattern being used to make a mold forming a
void or multiple voids having the same dimensions of first sand
cast sub-component 360, investment cast sub-components 362, and
second sand cast sub-component 368. After the mold is made,
investment cast sub-components 362 are placed in the mold and
carefully aligned so that locking features 364 on each investment
cast sub-component 362 are adjoining the voids that will eventually
form first sand cast sub-component 360 and second sand cast
sub-component 368.
[0053] Once investment cast sub-components 362 are aligned, the
mold is completed by placing the two molds in the first and second
molding boxes together. This creates the complete void having the
same shape as first sand cast sub-component 360 and another
complete void having the same shape as second cast sub-component
368. Then the two voids are filled with a sand casting material.
One material can be used to form first sand cast sub-component 360
and another material can be used to form second sand cast
sub-component 368 or the same material can be used to form both.
The sand casting materials completely fill the voids such that
locking features 364, which project into the voids, are surrounded
by the sand casting material. Finally, the sand casting materials
are solidified to create first sand cast sub-component 360
adjoining the outer side of investment cast sub-components 362 and
second sand cast sub-component 368 adjoining the inner side of
investment cast sub-components 362. Once the molds are removed and
final finishing is performed, turbine exhaust case 359 is a
finished apparatus with sub-components that are of different
materials.
[0054] The sub-components are prevented from movement relative to
one another through locking features 364, with an exemplary
embodiment shown in FIG. 5B as a dovetail configuration that
prevents first sand cast sub-component 360 from separating from
investment cast sub-component 362 (the structure forms a
geometrical configuration that does not allow sand cast
sub-component 360 to be pulled away from investment cast
sub-component 362; this configuration is known as a mechanical
engagement). While FIG. 5B shows locking feature 364 as a
projection having a dovetail configuration, locking feature 364 can
have various other configurations that prevent the sub-components
from moving relative to one another, with some examples shown in
previous figures.
[0055] As mentioned above, bondcasting process 10 includes
investment casting sub-process 12 and sand casting sub-process 14,
with new steps incorporated therein that are necessary to
manufacture a finished apparatus that has sub-components
constructed from multiple materials. Bondcasting process 10 can
omit investment casting sub-process 12 and can include another
sub-process suited to produce the first sub-component. Bondcasting
process 10 does not require the sub-components (the investment cast
sub-components and the sand cast sub-components) to be welded,
riveted, bolted, or otherwise fastened to one another after
bondcasting process 10 is complete because the sub-components will
be locked together through mechanical engagements. Bondcasting
process 10 can be performed even if a sub-component is constructed
from a material that has a relatively high melting point, like a
superalloy (such as a nickel based superalloy), and/or if a
sub-component requires hollow features or an opening within the
sub-component. Bondcasting process 10 can also be performed even if
a sub-component is too large to be efficiently constructed through
another casting process, such as die casting. Additionally,
bondcasting process 10 is flexible and allows for easy adjustment
to produce sub-components that are closer to the desired
configuration because the pattern and molds used to make the
finished apparatus can be formed and altered more easily than other
processes. This flexibility is important when multiple
sub-components are being constructed together to form a finished
apparatus.
Discussion of Possible Embodiments
[0056] The following are non-exclusive descriptions of possible
embodiments of the present invention.
[0057] A method of manufacturing an apparatus includes providing a
first sub-component having a locking feature with the first
sub-component being constructed from a superalloy, placing the
first sub-component into a void in sand in a sand molding box with
the void having a first portion shaped like the first sub-component
and a second portion shaped like a second sub-component and the
first sub-component sitting in the void such that the locking
feature is adjoining the second portion and the second portion is
unoccupied by the first sub-component, introducing a second
material in a fluidic state into the second portion so that the
second material is adjacent to at least a part of the locking
feature, and allowing the second material to solidify to form the
second sub-component adjoining the locking feature.
[0058] The method of the preceding paragraph can optionally
include, additionally and/or alternatively, any one or more of the
following features, configurations, steps, and/or additional
components:
[0059] The step of placing the first sub-component into the void in
the sand casting mold includes molding part of the first portion of
the void and part of the second portion of the void in a first sand
molding box through the use of a first pattern, placing at least a
part of the first sub-component into the part of the first portion
of the void, molding a remaining part of the first portion of the
void and a remaining part of the second portion of the void in a
second sand molding box through the use of a second pattern, and
placing the second sand molding box adjacent to the first sand
molding box.
[0060] The part of the first portion in the first sand molding box
and the remaining part of the first portion in the second sand
molding box form the void that has the same dimensions as the first
sub-component such that when at least a part of the first
sub-component is placed into the part of the first portion of the
first half of the sand molding box the sand in the first half of
the sand molding box is undisturbed and when the remaining part of
the first portion in the second half of the sand molding box is
placed adjacent to the first half of the sand molding box the sand
in the second half of the sand molding box is undisturbed.
[0061] The first sub-component is made up of a plurality of pieces
with each piece being similarly shaped and unattached to other
pieces of the first sub-component.
[0062] Aligning the plurality of pieces in the first portion of the
void.
[0063] The second sub-component has an annular shape and the
plurality of pieces of the first sub-component are arranged
radially within the second sub-component.
[0064] The locking feature is a projection that extends into the
second portion such that the second sub-component solidifies around
the locking feature.
[0065] The first sub-component includes at least one hollow
feature.
[0066] The melting temperature of the first material is higher than
the melting temperature of the second material.
[0067] The first component is constructed using investment
casting.
[0068] Performing final finishing on the first sub-component and
the second sub-component.
[0069] A method of making an apparatus constructed from at least
two different materials includes investment casting a first
sub-component constructed from a first material with the first
sub-component having a locking feature, placing a first pattern in
sand to create a first sand casting mold, placing a second pattern
in sand to create a second sand casting mold, removing the first
pattern and the second pattern, positioning the first sub-component
in a first impression in the first sand casting mold with the first
impression being sized to house at least a portion of the first
sub-component and the first sub-component being positioned so that
the locking feature is adjoining a second impression in the first
sand casting mold that has the same dimensions as at least a
portion of a second sub-component, assembling the first sand
casting mold and the second sand casting mold so that the first
sub-component is within a first cavity having the same dimensions
as the first sub-component and a second cavity having the same
dimensions as the second sub-component is formed adjacent to the
locking feature, introducing a second material in a fluidic state
into the second cavity to form the second sub-component, and
solidifying the second material within the second cavity adjoining
the locking feature.
[0070] The method of the preceding paragraph can optionally
include, additionally and/or alternatively, any one or more of the
following features, configurations, steps, and/or additional
components:
[0071] Removing the first sand casting mold and the second sand
casting mold from around the first sub-component and the second
sub-component.
[0072] The second sub-component solidifies around the locking
feature.
[0073] The first sub-component includes at least one hollow
feature.
[0074] A method of forming a component having a plurality of parts
constructed from at least two different materials includes forming
a first part made from a first material, placing a sandcasting
pattern in a sand molding box, filling the sand molding box with
sand, removing the sandcasting pattern from the sand molding box,
placing the first part in a first portion of a void in the sand
with the void formed by the removal of the sandcasting pattern,
filling a remaining area of the void with a second material, and
allowing the second material to solidify to form a second part.
[0075] The method of the preceding paragraph can optionally
include, additionally and/or alternatively, any one or more of the
following features, configurations, steps, and/or additional
components:
[0076] Forming a third part made from a third material and placing
the third part in a second portion of the void in the sand.
[0077] The first part and the third part are formed using
investment casting.
[0078] The first part is a plurality of similarly shaped
pieces.
[0079] The first part is made from a high temperature alloy.
[0080] Any relative terms or terms of degree used herein; such as
"substantially," "essentially," "generally," "approximately," and
the like; should be interpreted in accordance with and subject to
any applicable definitions or limits expressly stated herein. In
all instances, any relative terms or terms of degree used herein
should be interpreted to broadly encompass any relevant disclosed
embodiments as well as such ranges or variations as would be
understood by a person of ordinary skill in the art in view of the
entirety of the present disclosure, such as to encompass ordinary
manufacturing tolerance variations, incidental alignment
variations, alignment or shape variations induced by thermal,
rotational, or vibrational operations, and the like.
[0081] While the invention has been described with reference to an
exemplary embodiment(s), it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
* * * * *