U.S. patent application number 16/070594 was filed with the patent office on 2021-07-08 for manufacturing method and tooling for ceramic cores.
The applicant listed for this patent is Mikro Systems, Inc., Siemens Aktiengesellschaft. Invention is credited to Roy Eakins, Gary B. Merrill.
Application Number | 20210205876 16/070594 |
Document ID | / |
Family ID | 1000005504389 |
Filed Date | 2021-07-08 |
United States Patent
Application |
20210205876 |
Kind Code |
A1 |
Merrill; Gary B. ; et
al. |
July 8, 2021 |
MANUFACTURING METHOD AND TOOLING FOR CERAMIC CORES
Abstract
A method of manufacturing a tooling assembly and the tooling
assembly (10) for ceramic cores. The tooling assembly includes a
backing plate (12) comprising a top surface (20), side surfaces
(18), and a bottom surface (16) and a plurality of lithographically
derived inserts (14) each comprising a bottom surface (24), side
surfaces (26), and a positive top surface (28) and pieced together
on the top surface (20) of the backing plate (12). The method
includes providing the backing plate (12) and plurality of
lithographically derived inserts (14). A non-conformal positive
surface is generated from the plurality of lithographically derived
inserts (14). A negative flexible mold is created from the
non-conformal positive surface. The negative flexible mold is then
prepared for casting for an advanced ceramic core.
Inventors: |
Merrill; Gary B.; (Orlando,
FL) ; Eakins; Roy; (Madison, VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Siemens Aktiengesellschaft
Mikro Systems, Inc. |
Munchen
Charlottesville |
VA |
DE
US |
|
|
Family ID: |
1000005504389 |
Appl. No.: |
16/070594 |
Filed: |
March 18, 2016 |
PCT Filed: |
March 18, 2016 |
PCT NO: |
PCT/US2016/023017 |
371 Date: |
July 17, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22C 9/10 20130101 |
International
Class: |
B22C 9/10 20060101
B22C009/10 |
Claims
1. A master tooling assembly for ceramic cores, comprising: a
backing plate comprising a top surface, side surfaces, and a bottom
surface; a plurality of lithographically derived inserts each
comprising a bottom surface, side surfaces, and a positive top
surface, wherein the plurality of lithographically derived inserts
are pieced together on the top surface of the backing plate; a
second backing plate comprising a top surface, side surfaces, and a
bottom surface; and a second plurality of lithographically derived
inserts each comprising a bottom surface, side surfaces, and a
positive top surface, wherein the plurality of lithographically
derived inserts are pieced together on the top surface of the
second backing plate.
2. The master tooling assembly of claim 1, wherein the backing
plate and second backing plate are each a single step machined
surface.
3. The master tooling assembly of claim 1, wherein the plurality of
lithographically derived inserts comprises one hundred percent
surface coverage over the backing plate.
4. The master tooling assembly of claim 1, wherein the plurality of
lithographically derived inserts are pieced together by location
features in the master tool surface.
5. The master tooling assembly of claim 1, wherein the plurality of
lithographically derived inserts are pieced together by contour
location and interlocking edge features of the lithographically
derived inserts.
6. The master tooling assembly of claim 1, wherein the plurality of
lithographically derived inserts are pieced together by suction
ports located in the master tool.
7. The master tooling assembly of claim 1, wherein the plurality of
lithographically derived inserts are pieced together by reversible
thin layer bonding media.
8. A method of manufacturing of a tooling assembly for ceramic
cores, comprising: providing a plurality of lithographically
derived inserts and a second plurality of lithographically derived
inserts each comprising a bottom surface, side surfaces, and a
positive top surface; providing a backing plate and a second
backing plate each comprising a top surface, side surfaces and a
bottom surface, the backing plate and the second backing plate
provided as a locator surface; generating a non-conformal positive
surface from the plurality of lithographically derived inserts
pieced together and placed on the backing plate; generating a
non-conformal positive surface from the second plurality of
lithographically derived inserts pieced together and placed on the
second backing plate; creating a first negative flexible transfer
mold from the non-conformal positive surface of the plurality of
lithographically derived inserts; creating a second negative
flexible transfer mold from the non-conformal positive surface of
the second plurality of lithographically derived inserts; and
preparing the negative flexible molds for casting an advanced
ceramic core.
9. The method of tooling of claim 8, wherein the backing plate and
the second backing plate are each a single step machined
surface.
10. The method of claim 8, wherein the advanced ceramic core is for
a component within the power industry.
11. The method of claim 8, wherein the advanced ceramic core is for
a turbine blade.
Description
BACKGROUND
1. Field
[0001] The present invention relates to manufacturing advanced
ceramic cores and the master tooling for the manufacturing of
ceramic cores.
2. Description of the Related Art
[0002] In gas turbine engines, compressed air discharged from a
compressor section and fuel introduced from a source of fuel are
mixed together and burned in a combustion section, creating
combustion products defining a high temperature working gas. The
working gas is directed through a hot gas path in a turbine section
of the engine, where the working gas expands to provide rotation of
a turbine rotor. The turbine rotor may be linked to an electric
generator, wherein the rotation of the turbine rotor can be used to
produce electricity in the generator.
[0003] In view of high pressure ratios and high engine firing
temperatures implemented in modern engines, certain components,
such as airfoils, e.g., stationary vanes and rotating blades within
the turbine section, must be cooled with cooling fluid, such as air
discharged from a compressor in the compressor section, to prevent
overheating of the components.
[0004] Effective cooling of turbine airfoils requires delivering
the relatively cool air to critical regions such as along the
trailing edge of a turbine blade or a stationary vane. The
associated cooling apertures may, for example, extend between an
upstream, relatively high pressure cavity within the airfoil and
one of the exterior surfaces of the turbine blade. Blade cavities
typically extend in a radial direction with respect to the rotor
and stator of the machine.
[0005] Airfoils commonly include internal cooling channels which
remove heat from the pressure sidewall and the suction sidewall in
order to minimize thermal stresses. Achieving a high cooling
efficiency based on the rate of heat transfer is a significant
design consideration in order to minimize the volume of coolant air
diverted from the compressor for cooling. However, the relatively
narrow trailing edge portion of a gas turbine airfoil may include,
for example, up to about one third of the total airfoil external
surface area. The trailing edge is made relatively thin for
aerodynamic efficiency. Consequently, with the trailing edge
receiving heat input on two opposing wall surfaces which are
relatively close to each other, a relatively high coolant flow rate
is entailed to provide the requisite rate of heat transfer for
maintaining mechanical integrity.
[0006] Current methods of manufacturing ceramic cores for
investment casting in order to produce these blades and vanes
involve providing master tooling. Currently, the system to produce
master tooling includes multi axis machining of an aluminum block
to define the positive surface geometry of one side of a tooling
block. In areas where non-conformal features are required,
typically an insert is applied to the tooling surface to define
advanced tool surface geometry. Due to the non-conformal features,
these features are un-machinable. This insert has been manufactured
using either bonded photo chemically etched copper foils bonded to
make a three dimensional surface or electrical discharge machining
(EDM) machined insert.
[0007] From the master tool surfaces, or overall tool surfaces,
flexible mold liners are generated which becomes the casting vessel
for making advanced ceramic cores for investment casting. A metal
alloy component may be cast using a hollow ceramic core. The
ceramic core defines the shape of the open volume when the
component is cast within an outer casting shell.
[0008] As trailing edges become more advanced and fine feature
based the issue of cost is exacerbated further due to increasing
number of smaller features. When changes need to be made a whole
new core and master tooling needs to be manufactured at high costs.
Variants are not possible with this form of manufacturing. Rapid
changes are not possible with this form of manufacturing as
well.
SUMMARY
[0009] In an aspect of the present invention, a tooling assembly
for ceramic cores, comprises: a backing plate comprising a top
surface, side surfaces, and a bottom surface; a plurality of
lithographically derived inserts each comprising a bottom surface,
side surfaces, and a positive top surface, wherein the plurality of
lithographically derived inserts are pieced together on the top
surface of the backing plate; a second backing plate comprising a
top surface, side surfaces, and a bottom surface; and a second
plurality of lithographically derived inserts each comprising a
bottom surface, side surfaces, and a positive top surface, wherein
the plurality of lithographically derived inserts are pieced
together on the top surface of the second backing plate.
[0010] In another aspect of the present invention, a method of
manufacturing of a tooling assembly for ceramic cores, comprises:
providing a plurality of lithographically derived inserts and a
second plurality of lithographically derived inserts each
comprising a bottom surface, side surfaces, and a positive top
surface; providing a backing plate and a second backing plate each
comprising a top surface, side surfaces, and a bottom surface, the
backing plate and the second backing plate provided as a locator
surface; generating a non-conformal positive surface from the
plurality of lithographically derived inserts pieced together and
placed on the backing plate; generating a non-conformal positive
surface from the second plurality of lithographically derived
inserts pieced together and placed on the second backing plate;
creating a first negative flexible mold from the non-conformal
positive surface of the plurality of lithographically derived
inserts; creating a second negative flexible transfer mold from the
non-conformal positive surface of the second plurality of
lithographically derived inserts; and preparing the negative
flexible mold for casting an advanced ceramic core.
[0011] These and other features, aspects and advantages of the
present invention will become better understood with reference to
the following drawings, description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The invention is shown in more detail by help of figures.
The figures show preferred configurations and do not limit the
scope of the invention.
[0013] FIG. 1 is a perspective view of lithographically derived
inserts of the exemplary embodiments of the present invention;
[0014] FIG. 2 is a perspective view of a schematic of a portion of
a master tooling assembly with lithographically derived inserts in
an exemplary embodiment of the present invention; and
[0015] FIG. 3 is a side view of a schematic of a master tooling
assembly in an exemplary embodiment of the present invention.
DETAILED DESCRIPTION
[0016] In the following detailed description of the preferred
embodiment, reference is made to the accompanying drawings that
form a part hereof, and in which is shown by way of illustration,
and not by way of limitation, a specific embodiment in which the
invention may be practiced. It is to be understood that other
embodiments may be utilized and that changes may be made without
departing from the spirit and scope of the present invention.
[0017] Broadly, a method of manufacturing a tooling assembly and
the tooling assembly for ceramic cores. The tooling assembly
includes a backing plate comprising a top surface and a plurality
of lithographically derived inserts pieced together on the top
surface of the backing plate. The method includes providing the
backing plate and plurality of lithographically derived inserts. A
non-conformal positive surface is generated from the plurality of
lithographically derived inserts. A negative flexible mold is
created from the non-conformal positive surface. The negative
flexible mold is then prepared for casting for an advanced ceramic
core.
[0018] Within the power industry, gas turbine engines are required
to provide movement to produce electricity in a generator. In gas
turbine engines, compressed air discharged from a compressor
section and fuel introduced from a source of fuel are mixed
together and burned in a combustion section, creating combustion
products defining a high temperature working gas. The working gas
is directed through a hot gas path in a turbine section of the
engine, where the working gas expands to provide rotation of a
turbine rotor. The turbine rotor may be linked to an electric
generator, wherein the rotation of the turbine rotor can be used to
produce electricity in the generator.
[0019] Modern engines and certain components such as airfoils, e.g.
stationary vanes and rotating blades within the turbine section,
implement high pressure ratios and high engine firing temperatures.
As advancements are made, components are seeing higher and higher
temperatures and require more and more expensive materials to
produce these components.
[0020] As trailing edges on turbine blades become more advanced and
fine feature based, the manufacturing of these airfoils and the
costs involved become more important. The ability to change
manufacturing methods allows for a reduced cost and time savings.
Components are typically made from ceramic cores. For the purposes
of this application, any reference to a ceramic material may also
be any other material that functions in a similar fashion. Further,
the reference to turbines and the power industry may also be for
other processes and products that may require a core made from a
casting process. Producing a blade can require first a production
of a mold. The mold is produced from a master tooling surface.
[0021] A manufacturing process that allows for rapid low cost
master tooling and for multiple variants in the tooling assembly is
desirable. Embodiments of the present invention provide a method of
manufacturing that may allow for the reduction of cost in
manufacturing a master tooling assembly as well as the master
tooling assembly itself. The turbine blade and airfoil are used
below as an example of the method and tooling assembly; however,
the method and tooling assembly may be used for any component
requiring detailed features along a core for casting purposes. The
turbine blade can be within the power generation industry.
[0022] The method and tooling assembly mentioned below may be in
conjunction with a process that starts with a 3D computer model of
a part to be created. From the model a solid surface is created
from which a flexible mold can be created that is used in
conjunction with a second mating flexible mold to form a mold
cavity. The flexible mold is created from a machined master tool
representing roughly fifty percent of the surface geometry of the
core to be created. From such a tool, a flexible transfer mold can
be created. In order to form a mold cavity, a second half of the
master tool that creates a second flexible transfer mold, can be
combined with the first flexible transfer mold to form the mold
cavity. From such a mold cavity a curable slurry can be applied to
create a three dimensional component form. An example of such a
form can be a ceramic core used for investment casting.
[0023] In certain embodiments, such as a ceramic core used for
investment casting, materials of construction can be specifically
selected to work in cooperation with the casting and firing
processes to provide a core that overcomes known problems with
prior art cores. The materials and processes of embodiments of the
present invention may result in a ceramic body which is suitable
for use in a conventional metal alloy casting process.
[0024] As is illustrated in FIGS. 1 through 3, a master tooling
assembly 10 may be produced with a backing plate 12 and a plurality
of lithographically derived inserts 14. Precision machined surfaces
produced from computer numerical control (CNC) machines are
replaced with the plurality of lithographically derived inserts 14
and backing plate 12. A single step machined surface, the backing
plate 12, may serve as a locator surface for the plurality of
lithographically derived inserts 14 pieced together to define a
master tooling surface 22. Such features may include, but are not
limited to, simple mechanical interlocking features and/or
alignment locating features. Additionally, inserts may also be
bonded with reversible bonding compounds. The backing plate 12 may
be a single step machined surface. The backing plate 12 may include
a top surface 20, side surfaces 18, and a bottom surface 16.
[0025] The plurality of lithographically derived inserts 14 may be
produced by stereolithographic apparatus which converts liquid
plastic into solid objects. Such technology may be used to create
surface features not producible by traditional machining methods.
Such technology may also be used to produce accurate surface
tolerances as required for high definition applications.
[0026] Each of the plurality of lithographically derived inserts 14
may include a bottom surface 24, side surfaces 26, and a positive
top surface 28, that may become the master tooling surface 22. The
positive top surface 28 may be non-conformal. The plurality of
lithographically derived inserts 14 may expand across the entire
top surface 20 of backing plate 12. In certain embodiments, the
plurality of lithographically derived inserts 14 may include
various amounts of pieces. In certain embodiments, the plurality of
lithographically derived inserts 12 includes three through eight
inserts. The amount of plurality of lithographically derived
inserts 14 may depend upon the complexity of the surface geometry
and the degree of flexibility requested.
[0027] A method of manufacturing the master tooling assembly 10 for
ceramic cores may include providing the plurality of
lithographically derived inserts 14. The backing plate 12 may be
provided as a locating surface for the plurality of
lithographically derived inserts 14. The plurality of
lithographically derived inserts 14 may be pieced together and
placed on the backing plate 12. A non-conformal positive surface is
generated from the plurality of lithographically derived inserts 14
pieced together. Examples of piecing together or combining a
plurality of lithographically derived inserts 14 may involve, but
is not limited to, 1) interlocking into the backing plate 12, 2)
precision thin layer bonding, and 3) vacuum assisted surface
contacting. The precision thin layer bonding may be with
accomplished with a reversible thin layer bonding media. The
backing plate 12 may include suction ports located in the top of
the plate 20. Once the plurality of lithographically derived
inserts 14 is set in position along the backing plate 12, a portion
of the master tooling assembly 10 may be complete.
[0028] The plurality of lithographically derived inserts 14 and the
backing plate 12 may form a first half 32 of a master tool. A
second half 34 of the master tool may be formed by a second
plurality of lithographically derived inserts 14 and a second
backing plate 38. The second backing plate 38 may include a top
surface 20, side surfaces 18, and a bottom surface 16. The second
half 34 of the master tool may be combined with the first half 32
of the master tool to form a mold cavity. The combining of the
first half 32 and the second half 34 of the master tool provides
the master tooling assembly 10. Two negative flexible transfer
molds may be created from the non-conformal positive surfaces of
the plurality of lithographically derived inserts 14 and a second
plurality of lithographically derived inserts 36 respectively. The
negative flexible transfer molds may then be combined to produce a
mold cavity into which a slurry can be introduced and cured to
create a ceramic green body (ceramic core). The advanced ceramic
core may be used for the investment casting of an advanced turbine
blade. The second plurality of lithographically derived inserts 36
and the second backing plate 38 have the same properties as the
plurality of lithographically derived inserts 14 and the backing
plate 12 except for the second plurality of lithographically
derived inserts 36 may have different non-conformal positive
surfaces. Each of the second plurality of lithographically derived
inserts 36 may include a bottom surface 24, side surfaces 26, and a
positive top surface 28, that may become the master tooling surface
22.
[0029] As mentioned above, the backing surface may be a single step
machined surface. Each of the plurality of lithographically derived
inserts 14 and second plurality of lithographically derived inserts
36 may be interchanged for other lithographically derived inserts
14, 36 for minor changes. In applications where rapid iterations
and prototypes need to be made, this method with interchangeable
plurality of lithographically derived inserts 14 and second
plurality of lithographically derived inserts 36 allows for quick
adjustments. The tooling assembly, being readily adjustable, allows
for a reduction in manufacturing costs and reduces the time in
between required changes. FIG. 1 shows an example of advanced
detailed features 30 of the plurality of lithographically derived
inserts 14 for a turbine component.
[0030] While specific embodiments have been described in detail,
those with ordinary skill in the art will appreciate that various
modifications and alternative to those details could be developed
in light of the overall teachings of the disclosure. Accordingly,
the particular arrangements disclosed are meant to be illustrative
only and not limiting as to the scope of the invention, which is to
be given the full breadth of the appended claims, and any and all
equivalents thereof
* * * * *