U.S. patent application number 17/480642 was filed with the patent office on 2022-03-10 for rotor construction for high speed motors.
The applicant listed for this patent is Ingersoll-Rand Industrial U.S., Inc.. Invention is credited to George C. Hansen, James Lawrence Robb, Juha Tuomas Saari.
Application Number | 20220074317 17/480642 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-10 |
United States Patent
Application |
20220074317 |
Kind Code |
A1 |
Robb; James Lawrence ; et
al. |
March 10, 2022 |
ROTOR CONSTRUCTION FOR HIGH SPEED MOTORS
Abstract
A rotor shaft for a high speed motor that has a coating that is
secured to a shaft body. The coating and the shaft body are formed
from dissimilar materials. More specifically, the coating may be an
alloy material, such as, for example, a copper alloy, while the
shaft body may be a steel material. According to certain
embodiments, the alloy material of the coating may be secured to at
least a portion of a rotor body blank in a solution treated
condition via a low temperature welding procedure. Additionally,
the coating may be hardened, such as for example, through the use
of an age hardening process. The coating and the rotor body blank
may be machined together to form the rotor shaft. According to
certain embodiments, such machining may configure the rotor shaft
for use with a turbo-compressor that is configured for air
compression.
Inventors: |
Robb; James Lawrence; (China
Grove, NC) ; Saari; Juha Tuomas; (Espoo, FI) ;
Hansen; George C.; (Onalaska, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ingersoll-Rand Industrial U.S., Inc. |
Davidson |
NC |
US |
|
|
Appl. No.: |
17/480642 |
Filed: |
September 21, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16377950 |
Apr 8, 2019 |
11125107 |
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17480642 |
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14973121 |
Dec 17, 2015 |
10253649 |
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16377950 |
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62098818 |
Dec 31, 2014 |
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International
Class: |
F01D 25/00 20060101
F01D025/00; F01D 5/02 20060101 F01D005/02; C09D 5/24 20060101
C09D005/24; F04D 29/02 20060101 F04D029/02; F04D 29/043 20060101
F04D029/043; H02K 1/22 20060101 H02K001/22; H02K 17/16 20060101
H02K017/16; H02K 15/00 20060101 H02K015/00 |
Claims
1-21. (canceled)
22. A method for manufacturing a rotor shaft for a high speed
motor, the method comprising: forming a rotor body blank from a
steel material; solution heat treating an alloy material, wherein a
duration of heat treating the alloy material is dependent on a
thickness of the alloy material, the alloy material and the steel
material of the rotor body blank being different materials;
securing the solution treated alloy material to at least a portion
of the rotor body blank to provide a coating; heat treating the
coating when the coating is secured to the rotor body blank, the
heat treating process adapted to minimize the loss of a core
property of the steel material of the rotor body blank; and
machining the rotor body blank and the coating to form the rotor
shaft, the rotor shaft configured for operation in the high speed
motor.
23. The method of claim 22, wherein the duration of heat treating
the alloy material ranges from three minutes to three hours.
24. The method of claim 22, wherein the alloy material is a copper
alloy.
25. The method of claim 24, wherein the step of securing the alloy
material includes using a low temperature welding process.
26. The method of claim 25, wherein the step of securing the alloy
material includes using explosion welding to cover the at least a
portion of the rotor body blank with the alloy material.
27. The method of claim 25, wherein the step of heat treating the
coating includes age hardening the coating.
28. The method of claim 27, further including the step of stress
relieving the coating.
29. The method of claim 28, wherein the rotor shaft is manufactured
to operate at a tip speed greater than 300 meters/second.
30. The method of claim 28, wherein the step of machining the rotor
body blank and the coating includes forming the rotor shaft for use
with a turbo-compressor that is configured for air compression.
31. A method for manufacturing a rotor shaft for a high speed
motor, the method comprising: providing a rotor body blank from a
steel material; providing an alloy material which has been solution
heat treated, the alloy material and the steel material of the
rotor body blank being different materials; securing the alloy
material which has been solution heat treated to at least a portion
of the rotor body blank to provide a coating; and heat treating the
coating when the coating is secured to the rotor body blank.
32. The method of claim 31, wherein the alloy material is a copper
alloy.
33. The method of claim 32, wherein the step of securing the alloy
material includes using a low temperature welding process.
34. The method of claim 33, wherein the step of securing the alloy
material includes using explosion welding to cover the at least a
portion of the rotor body blank with the alloy material.
35. The method of claim 33, wherein the step of heat treating the
coating includes age hardening the coating.
36. The method of claim 35, further including the step of stress
relieving the coating.
37. A method for manufacturing a rotor shaft for a high speed
motor, the method comprising: forming a rotor body blank from a
steel material; solution treating an alloy material, the alloy
material and the steel material of the rotor body blank being
different materials; securing the solution treated alloy material
to at least a portion of the rotor body blank to provide a coating;
heat treating the coating when the coating is secured to the rotor
body blank, the heat treating process adapted to minimize a
strength loss of the steel material; and machining the rotor body
blank and the coating to form the rotor shaft, the rotor shaft
configured for operation in the high speed motor.
38. The method of claim 37, wherein the alloy material is a copper
alloy.
39. The method of claim 38, wherein the step of securing the alloy
material includes using a low temperature welding process.
40. The method of claim 39, wherein the step of securing the alloy
material includes using explosion welding to cover the at least a
portion of the rotor body blank with the alloy material.
41. The method of claim 39, wherein the step of heat treating the
coating includes age hardening the coating.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/098,818, filed Dec. 31, 2014, which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] A variety of different technologies, such as, for example,
high speed, direct drive turbo-compressors, utilize high speed
motors. Often, the operating speed of high speed motors, including
asynchronous and synchronous motors, may be limited at least in
part by the construction of the associated rotor. For example, due
to the development of stresses in the magnet retention sleeve,
typical permanent magnet motors may often be limited to achievable
tip speeds of approximately 150 meters/second (m/s). Additionally,
the laminated construction of asynchronous motors, such as, for
example, induction motors, may also limit asynchronous motors to
similar achievable tip speeds. Yet, to the detriment of the
performance and reliability of the equipment that is being driven
by the motor, lower tip speeds may impair the ability of the motor
to obtain greater power density or more critical speed margins.
[0003] Prior attempts to overcome tip speed limitations have
included the use of solid steel rotors. While such solid steel
construction for the rotor may allow for higher achievable tip
speeds, such as, for example, tip speeds in excess of 300
meters/second (m/s), and even tip speeds in excess of 500
meters/second (m/s), the electrical conductively of steel is
typically too low for the associated machines to be designed with
acceptable efficiency. Attempts to overcome conductivity
deficiencies with solid steel rotors have included applying a
copper coating to the solid steel rotor. Such construction utilizes
the copper coating to carry an induced current at the surface of
the rotor and to act as the rotor cage. Yet, with such
construction, the peripheral speed of the rotor is limited to the
coating strength and/or the strength of the bond between the copper
coating and the steel rotor body. Further, the joining of
dissimilar metals such as copper and steel, as well differences in
their properties, such as, for example, melting temperatures, may
limit the manner in which these two metals may be joined or bonded.
For example, typically in rotor applications, the copper is applied
to the steel rotor body via explosion welding, wherein the copper
is able to come into close enough contact with the surface of the
steel rotor body to form a weld. Yet, for at least certain
applications, such bonding may be insufficient to allow the copper
coated steel rotor to achieve the prerequisite degree of
durability. For example, such bonding may be insufficient for
turbo-compressor applications in which the motor is relatively
frequently started and stopped and/or is exposed to relatively high
temperatures.
BRIEF SUMMARY
[0004] One aspect of the present disclosure is a rotor shaft for a
high speed motor. The rotor shaft includes a shaft body and a
coating. The shaft body is configured for rotational displacement
during operation of the high speed motor, and is constructed from a
steel material. The coating is secured to at least a portion of an
outer surface of the shaft body. Additionally, the coating is an
alloy material that is configured to carry an induced electrical
current for the rotational displacement of the shaft body. Further,
the alloy material of the coating and the steel material of the
shaft body are dissimilar materials.
[0005] Another aspect of the present disclosure is a method for
manufacturing a rotor shaft body for a high speed motor. The method
includes forming a rotor body blank from a steel material.
Additionally, an alloy material, which is a material different than
the steel material of the rotor blank, is solution heat-treated
prior to the cladding operation. The solution treated alloy
material is secured to at least a portion of the rotor body blank
to provide a coating. Further, the coating may undergo subsequent
heat treating, such as, for example, age hardening. Additionally,
the rotor body blank and the coating are machined to form a rotor
shaft that is configured for operation in a high speed motor.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0006] FIG. 1 is a cross sectional view of a rotor shaft body for a
turbo-compressor that is at least partially coated with a
dissimilar metal material according to an embodiment of the present
disclosure.
[0007] FIG. 2 is a cross sectional view of a rotor shaft body blank
having a coating of a dissimilar material according to an
embodiment of the present disclosure.
[0008] FIG. 3 is a flow diagram of a process for manufacturing a
solid steel rotor shaft body that includes a copper alloy coating
according to an embodiment of the present disclosure.
[0009] The foregoing summary, as well as the following detailed
description of certain embodiments of the present disclosure, will
be better understood when read in conjunction with the appended
drawings. For the purpose of illustrating the disclosure, there is
shown in the drawings, certain embodiments. It should be
understood, however, that the present disclosure is not limited to
the arrangements and instrumentalities shown in the attached
drawings.
DETAILED DESCRIPTION
[0010] FIG. 1 is a cross sectional view of a rotor shaft 10 for a
turbo-compressor that includes a shaft body 12 that is at least
partially coated with a coating 14 of a dissimilar material
according to an embodiment of the present disclosure. As shown, in
the illustrated embodiment, the shaft body 12 is operably connected
to impellers 16a, 16b of low and high pressure compressors,
respectively. According to the illustrated embodiment, the shaft
body 12 has a generally unitary and/or solid body construction. For
example, the shaft body 12 may be a forged, machined, and/or molded
piece of metal, such as steel, that provides and/or assists in
attaining the desired rotor shaft body 12 size(s) and
configuration.
[0011] In the embodiment illustrated in FIG. 1, the coating 14 may
be a metal that is dissimilar to the metal of the rotor shaft body
12. For example, according to the illustrated embodiment, the rotor
shaft body 12 is constructed from steel, while the coating 14 can
be a copper or copper alloy material, such as, for example, copper
chromium (UNS No. C18200) or copper chromium zirconium (UNS No.
C18150), among other copper alloys. Other suitable coating
materials as would be known to one skilled in the art are also
contemplated by the present disclosure. The selection of the
material for the coating 14 may be based on a variety of different
criteria. For example, the material for the coating 14 may be
selected to improve the electrical connectivity characteristics of
the rotor shaft 10 to levels beyond the connectively
characteristics of the shaft body 12. Further, the material for the
coating 14 may be selected based on the manner in which the coating
14 may be applied to and/or bonds with the material of the shaft
body 12. Moreover, the coating 14 material may be selected based on
the mechanical properties of the coating 14 and/or the properties
of the bond between, or attachment of, the coating 14 and/to the
shaft body 12.
[0012] FIG. 3 is a flow diagram of a process 100 for manufacturing
a rotor shaft 10 that includes a copper alloy coating 14 according
to an embodiment of the present disclosure. At step 110, a rotor
body blank 18, as shown for example in FIG. 2, is formed from a
steel material. Such forming may include, for example, forging,
casting, and/or machining the rotor body blank 18 to obtain a
particular shape, size, and/or configuration. For example, for
illustration purposes, FIG. 2 illustrates a rotor body blank 18
that has been formed, turned or otherwise milled to a diameter that
is approximately equal to the largest diameter of the shaft body
12.
[0013] At step 120, a metal coating material that is to be used for
the coating 14, such as, for example, an age-hardenable copper
alloy, may be solution treated in preparation for age hardening
after the bonding process. For example, according to certain
embodiments, a copper alloy that is to be used for the coating 14
may undergo solution heat treatment. Thus, according to certain
embodiments, the copper alloy may be subjected to a high
temperature soak, such as, for example, being subjected to
temperatures of approximately 1450-1850 degrees Fahrenheit. The
duration of the high temperature soak may be based on a variety of
different factors, including, for example, the thickness of the
copper alloy that is undergoing the solution treatment. For
example, according to certain embodiments, the copper alloy may
undergo the heat soak for approximately three minutes to
approximately three hours. Additionally, according to certain
embodiments, the high temperature soak may be followed by air
cooling or quenching of the copper alloy, such as, for example,
quenching the copper alloy in a water quench. By solution treating
the coating material, the coating material may be in a relatively
softer condition, and thus have improved ductility and plasticity
characteristics. Also by solution treating the coating material
prior to bonding the coating material to the rotor body blank 18,
the bonding performance and process reliability of the bond between
the coating 14 and the rotor body blank 18 can be improved.
Moreover, solution treating the coating material, and thereby
adjusting the relative hardness of the coating material to the
material of the rotor body blank 18, may allow for the bonding
process to be less prone to defects. For example, the solution
treatment process may increase the ductility of the coating
material, thereby improving the plastic flow of the coating
material. Further, by improving the plastic flow of the coating
material, the bonding process may be more uniform and tolerant of
parameter variations, including, for example, standoff gap and
explosive velocity, among other parameters, which may thereby
improve the reliability of the bond between the coating 14 and the
rotor body blank 18.
[0014] At step 130, the metal coating material for the coating 14
may, while in the solution treated condition, be secured, such as,
for example, bonded, to at least a portion of the rotor body blank
18 to provide a coating 14, as shown in FIG. 2. For example,
according to certain embodiments, a copper alloy coating 14 may be
bonded to the rotor body blank 18 using a low temperature, high
integrity bonding process, such as, for example, via explosion
welding or explosive bonding, diffusion bonding, or hot-isostatic
pressing, among other bonding processes. Further, the improved
ductility and plasticity characteristics of the solution treated
coating material may reduce the propensity for cracks forming in
the coating material and/or along the coating 14 and rotor body
blank 18 interface from or during the application and/or bonding of
the coating material to the rotor body blank 18. Such reduction in
cracking may improve the overall integrity of the resulting coating
14 and/or the bond between the coating 14 and the rotor body blank
18.
[0015] At step 140, the coating 14 on the rotor body blank 18 or
shaft body 12 may be heat treated. For example, according to
certain embodiments, a copper alloy coating 14 may undergo
precipitation hardening or age hardening so that the copper alloy
of the coating 14 attains a desired strength level, hardness,
and/or electrical conductivity characteristics. Such heat treating
of the coating 14 at step 140 may provide the coating 14 with at
least a hardened outer portion that improves the ability of the
coating 14 to resist creep and fatigue, including temperature
dependent creep. According to certain applications, such as, for
example, high speed motor applications, the heat treatment process
employed at step 140 may seek to attain a higher degree of coating
14 strength at the possible detriment of the ductility
characteristics of the coating 14. Conversely, in other
applications, such as, for example, applications in which the
cyclic loading capability of the rotor shaft 10 may be of greater
emphasis, the heat treatment process employed may be tailored to
obtaining enhanced ductility characteristics of the coating 14 to
the possible detriment of the hardness of the coating 14.
[0016] For example, according to certain embodiments in which the
coating 14 is a copper alloy such as copper chromium, the copper
alloy may be elevated to the alloy's solution precipitation
temperature so that chromium is precipitated out of the solid
solution. More specifically, according to certain embodiments in
which the copper alloy is C18200, the copper alloy may be subjected
to a temperature of approximately 795 to 935 degrees Fahrenheit for
approximately two to four hours. However, the particular heat
treatment process employed, and the associated procedure, may also
consider core properties of the steel of the rotor body blank 18 so
that the properties or mechanical characteristics of the resulting
shaft body 12 are not adversely impacted by the heat treatment
process. For example, age hardening of the coating 14 may occur at
temperatures that seek to avoid tempering the steel material of the
rotor shaft 10, and thereby prevent or minimize the age hardening
process from adversely impacting core properties of the steel
material of the rotor shaft 10, such as, for example, the strength
of the steel, among other properties.
[0017] At step 150, the rotor body blank 18 having a coating 14 may
be machined to the size, shape, and/or configuration of the rotor
shaft 10. According to certain embodiments, such machining may
remove at least a portion of the coating 14 that had been applied
to the rotor body blank 18, as well as a portion of the steel
material of the rotor body blank 18. Further, such machining may be
performed before or after the coating 14 that has been applied to
the rotor body blank 18 has been heat treated, such as before or
after step 140. Further, according to certain embodiments in which
the machining of step 150 occurs after the heat treatment process
of step 140, the coating 14 remaining on the shaft body 12 may
undergo further stress relieving treatment.
[0018] In one aspect, the present disclosure includes a rotor shaft
for a high speed motor, the rotor shaft comprising: a shaft body
configured for rotational displacement during operation of the high
speed motor, the shaft body being constructed from a steel
material; and a coating secured to at least a portion of an outer
surface of the shaft body, the coating configured to carry an
induced electrical current for the rotational displacement of the
shaft body, the coating being an alloy material, the alloy material
of the coating and the steel material of the shaft body being
dissimilar materials.
[0019] In refining aspects, the present disclosure includes a rotor
shaft, wherein the alloy material is a copper alloy; wherein the
coating is secured to the shaft body by a low temperature bonding
process; wherein the coating is secured to the shaft body by
explosion welding; wherein the coating is an age hardened material;
wherein the shaft body has a unitary construction; wherein the
rotor shaft is configured to operate at a tip speed greater than
300 meters/second; wherein the rotor shaft is configured for use
with a turbo-compressor that is configured for air compression;
wherein the copper alloy is copper chromium; and wherein the copper
alloy is copper chromium zirconium.
[0020] In another aspect, the present disclosure includes a method
for manufacturing a rotor shaft for a high speed motor, the method
comprising: forming a rotor body blank from a steel material;
solution treating an alloy material, the alloy material and the
steel material of the rotor body blank being different materials;
securing the solution treated alloy material to at least a portion
of the rotor body blank to provide a coating; heat treating the
coating when the coating is secured to the rotor body blank, the
heat treating process adapted to minimize the loss of a core
property of the steel material of the rotor body blank; and
machining the rotor body blank and the coating to form the rotor
shaft, the rotor shaft configured for operation in a high speed
motor.
[0021] In refining aspects, the present disclosure includes a
method for manufacturing a rotor shaft for a high speed motor,
wherein the alloy material is a copper alloy; wherein the step of
securing the alloy material includes using a low temperature
welding process; wherein the step of securing the alloy material
includes using explosion welding to cover at least a portion of the
rotor body blank with the alloy material; wherein the step of heat
treating the coating includes age hardening the coating; further
including the step of stress relieving the coating; wherein the
rotor shaft is manufactured to operate at a tip speed greater than
300 meters/second; wherein the step of machining the rotor body
blank and the coating includes forming the rotor shaft for use with
a turbo-compressor that is configured for air compression; wherein
the step of heat treating the coating includes enhancing the
ductility of the coating; wherein the step of heat treating the
coating includes enhancing the hardness of the coating; and wherein
the step of heat treating includes enhancing the temperature
dependent creep resistance of the coating.
[0022] While the disclosure has been described with reference to
certain embodiments, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted without departing from the scope of the disclosure. In
addition, many modifications may be made to adapt a particular
situation or material to the teachings of the disclosure without
departing from its scope. Therefore, it is intended that the
disclosure not be limited to the particular embodiment disclosed,
but that the disclosure will include all embodiments falling within
the scope of the appended claims.
* * * * *