U.S. patent application number 14/566041 was filed with the patent office on 2016-06-16 for process for lobe and journal preparation and weld repair.
This patent application is currently assigned to Caterpillar Inc.. The applicant listed for this patent is Caterpillar Inc.. Invention is credited to Larry Bright, Daniel Cavanaugh, Eric Jeffery, Kegan Luick, Jeffery Stark.
Application Number | 20160169056 14/566041 |
Document ID | / |
Family ID | 56110689 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160169056 |
Kind Code |
A1 |
Luick; Kegan ; et
al. |
June 16, 2016 |
Process for Lobe and Journal Preparation and Weld Repair
Abstract
A process for repairing a section of a rotatable shaft is
disclosed. The section of the rotatable shaft has a surface portion
having a surface parallel to an axis of rotation of the rotatable
shaft and axial ends perpendicular to the axis of rotation of the
rotatable shaft. The process includes preparing a well region
extending over a perimeter of the section and extending downward in
the surface portion, depositing material into the well region to
fill the well region using a welding process and displacing a
portion of the material that was deposited in the well region. The
well region has a bottom portion that is substantially parallel to
the axis of rotation and includes opposing sidewalls. Each sidewall
extends proximate to the axial ends of the rotatable shaft and
directly adjoins a remaining portion of the surface portion.
Inventors: |
Luick; Kegan; (Corinth,
MS) ; Stark; Jeffery; (Corinth, MS) ; Bright;
Larry; (Walnut, MS) ; Cavanaugh; Daniel;
(Chillicothe, IL) ; Jeffery; Eric; (Peoria,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Caterpillar Inc. |
Peoria |
IL |
US |
|
|
Assignee: |
Caterpillar Inc.
Peoria
IL
|
Family ID: |
56110689 |
Appl. No.: |
14/566041 |
Filed: |
December 10, 2014 |
Current U.S.
Class: |
29/888.1 |
Current CPC
Class: |
F01L 2001/0476 20130101;
F01L 2001/054 20130101; F01L 2301/00 20200501; F01L 1/047
20130101 |
International
Class: |
F01L 1/047 20060101
F01L001/047 |
Claims
1. A process of repairing a section of a rotatable shaft, wherein
the section includes a surface portion having a surface parallel to
an axis of rotation of the rotatable shaft, the section includes
axial ends perpendicular to the axis of rotation of the rotatable
shaft, the process comprising: (a) preparing a well region
extending over a perimeter of the section and extending downward in
the surface portion, the well region having a bottom portion that
is substantially parallel to the axis of rotation and includes
opposing sidewalls, wherein each sidewall extends proximate to the
axial ends of the section and directly adjoins a remaining portion
of the surface portion; (b) depositing material into the well
region to fill the well region using a welding process; and (c)
displacing a portion of the material that was deposited in the well
region.
2. The process of claim 1, wherein the section is one of the
following: a lobe or a journal.
3. The process of claim 2, wherein the rotatable shaft is a
camshaft.
4. The process of claim 1, wherein the preparing includes forming
fillets between the bottom portion and the sidewalls.
5. The process of claim 1, wherein the preparing utilizes a milling
process.
6. The process of claim 5, wherein the preparing includes at least
one of the following: milling with a key slot cutter or milling
with a ball nose end mill.
7. The process of claim 1, wherein the depositing includes
depositing using Laser Beam (LB) Welding.
8. The process of claim 7, further comprising providing argon gas
during the depositing.
9. The process of claim 1, wherein the depositing includes
depositing with at least one of the following: Plasma Transfer Arc
(PTA) Welding, Electron Beam (EB) Welding, Metal Inert Gas (MIG)
Welding or Tungsten Inert Gas (TIG) Welding.
10. The process of claim 1, wherein the depositing includes
providing one of the following gases proximate to the welding
process: argon, carbon dioxide or helium.
11. The process of claim 1, wherein the displacing includes
displacing utilizing at least one of the following: a grinding
process or a machining process.
12. The process of claim 1, wherein the material deposited is
steel.
13. The process of claim 1, wherein the depositing includes
depositing a powder material.
14. The process of claim 1, wherein the depositing includes
depositing a wire material.
15. The process of claim 1, wherein the rotatable shaft is a
component of one of the following: a turbine, a turbocharger, a
starter, a motor, an alternator, a water pump, a hydraulic pump, a
fuel pump, a coolant pump, an oil pump, a transmission, an
auxiliary system for a vehicle, or a drivetrain.
16. The process of claim 1, further comprises pre-weld heat
treatment of the section after the preparing and prior to the
depositing.
17. The process of claim 1, further comprises post-weld heat
treatment of the section after the depositing and prior to the
displacing.
18. The process of claim 1, wherein the section extends
eccentrically from the rotatable shaft.
19. A process of repairing a section of a rotatable shaft, wherein
the section extends eccentrically from the rotatable shaft and
includes a surface portion having a surface parallel to an axis of
rotation of the rotatable shaft, the section includes axial ends
perpendicular to the axis of rotation of the rotatable shaft, the
process comprising: (a) milling a well region extending over a
perimeter of the section and extending downward in the surface
portion, the well region having a bottom portion that is
substantially parallel to the axis of rotation, and opposing
sidewalls, wherein each sidewall extends proximate to the axial
ends of the section and directly adjoins a remaining portion of the
surface portion; (b) depositing material into the well region to
fill the well region by using laser beam welding; and (c) grinding
a portion of the material that was deposited in the well
region.
20. The process of claim 19, wherein the preparing includes forming
fillets between the bottom portion and opposing sidewalls and the
depositing includes at least one of the following: depositing a
powder material or a wire material.
Description
TECHNICAL FIELD
[0001] The disclosure generally relates to a process for repairing
a section of a rotatable shaft, and more particularly to a process
of repairing a section of a rotatable shaft, such as a lobe or a
journal utilizing welding processes.
BACKGROUND
[0002] Rotatable shafts having eccentric features formed on
portions of their outer surfaces are commonly used in various
machines requiring cyclically timed mechanical events or actuations
of various components. For example, an internal combustion engine
may use a rotating camshaft for timed actuation of intake or
exhaust valves controlling the flow of air and exhaust into and out
from one or more combustion chambers. Camshafts are typically
unitary structures having lobes or eccentric features protruding
therefrom. The lobes are arranged to periodically push a roller or
follower connected to another engine component, where the roller or
follower tracks an outer periphery or race of each lobe.
[0003] In a typical camshaft application, each lobe is typically
continuously in contact with a roller or follower. The interface
between the cam lobe and follower is subject to compressive forces
and friction, causing wear and/or damage to the lobe during
prolonged use, or when a defective condition is present. For
example, in instances where inadequate lubrication of the interface
is provided and/or situations when the follower is not properly
aligned with its respective lobe, wear and/or damage to the lobe
may occur. Prolonged extensive use will result in wear as well. A
damaged and/or worn lobe may directly affect the motion of the
follower and, hence, operation of the engine. Therefore, it is
necessary to either replace or rebuild the camshaft.
[0004] One of the challenges associated with rebuilding camshafts
is rebuilding the eccentric features, such as lobes and journals,
on the shaft. These eccentric features commonly have portions that
stand proud of the minor diameter of the feature creating raised,
square-edged, stepped profiles. It is difficult to efficiently
rebuild these features and, in particular to rebuild the
square-edge original to the feature due to welding dynamics and
weld bead surface tension. Economic considerations, however,
dictate that it is usually more desirable to rebuild a worn
camshaft instead of replacing the worn camshaft with a new one.
[0005] Different welding strategies have been employed to repair
the worn portions of rotatable shafts and address issues associated
with the repair such as downtime and material costs. For example,
U.S. Pat. No. 5,172,475 ("Amos et al.") issued Dec. 22, 1992
discloses a prior art method for repairing a rotor that entails
severing the rotor into two or more segments, removing the crack
from the rotor and depositing weld material onto the rotor until
the removed portion is replaced with weld metal. Additional welding
is performed to build up enough stock to machine a welding
preparation, which is used to provide a surface to weld together
the rotor body 14 and the stub end 18. See Col. 2, lines 24-55, and
FIGS. 1 and 2.
[0006] While prior art methods of repairing worn rotatable shafts
are useful to some extent, these methods do not specifically
address the difficulties associated with welding eccentric features
such as lobes and journals. Therefore, there remains a need to more
efficiently repair rotatable shafts, including features such as
lobes and journals while maintaining the square edge original to
the feature. Accordingly, the disclosed process for repairing a
section of a rotatable shaft is directed at overcoming one or more
of these disadvantages in currently available repair methods.
SUMMARY
[0007] In accordance with one aspect of the disclosure, a process
for repairing a section of a rotatable shaft is disclosed. The
section of the rotatable shaft includes a surface portion having a
surface parallel to an axis of rotation of the rotatable shaft. The
section of the rotatable shaft further includes axial ends
perpendicular to the axis of rotation of the rotatable shaft. The
process includes preparing a well region extending over a perimeter
of the section and extending downward in the surface portion. The
well region has a bottom portion that is substantially parallel to
the axis of rotation and includes opposing sidewalls. Each sidewall
extends proximate to the axial ends of the section and directly
adjoins a remaining portion of the surface portion. The process
further includes depositing material into the well region to fill
the well region using a welding process and displacing a portion of
the material that was deposited in the well region.
[0008] In accordance with another aspect of the disclosure, a
process of repairing a section of a rotatable shaft is disclosed.
The section extends eccentrically from the rotatable shaft and
includes a surface portion having a surface parallel to an axis of
rotation of the rotatable shaft. The section also includes axial
ends perpendicular to the axis of rotation of the rotatable shaft.
The process includes milling a well region extending over a
perimeter of the section and extending downward in the surface
portion. The well region has a bottom portion that is substantially
parallel to the axis of rotation and includes opposing sidewalls.
Each sidewall extends proximate to the axial ends of the section
and directly adjoins a remaining portion of the surface portion.
The process further includes depositing material into the well
region to fill the well region by using laser clad welding and
grinding a portion of the material that was deposited in the well
region.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The above-mentioned and other features and advantages of
this disclosure, and the manner of attaining them, will become
apparent and be better understood by reference to the following
description of one aspect of the disclosure in conjunction with the
accompanying drawings, wherein:
[0010] FIG. 1 is a front plan view of a section of a rotatable
shaft that may utilize the process according to an aspect of the
disclosure.
[0011] FIG. 2 is a flowchart of the process of repairing a section
of a rotatable shaft according to an aspect of the disclosure.
[0012] FIG. 3 is a front plan view of the section of the rotatable
shaft shown in FIG. 1 after the well region is prepared according
to an aspect of the disclosure.
[0013] FIG. 4 is a partial cross-section view of the section shown
in FIG. 3 cut along the axis of rotation according to an aspect of
the disclosure.
[0014] FIG. 5 is a graphical representation of the process of
repairing a section of the rotatable shaft according to an aspect
of the disclosure.
[0015] FIG. 6 is a combustion engine having components that may be
repaired utilizing aspect of the disclosure.
DETAILED DESCRIPTION
[0016] FIG. 1 is a front plan view of a section of a rotatable
shaft that may utilize the process according to an aspect of the
disclosure. Referring to FIG. 1, a section 10 of the rotatable
shaft 20 is shown. The rotatable shaft 20 may be an elongated
member, such as, for example, a camshaft. The rotatable shaft 20
has an axis of rotation A and is configured to rotate three-hundred
and sixty degrees (360 degrees) around the axis of rotation A. The
rotatable shaft 20 may be driven to rotate, such as, for example,
by a camshaft drive, chain, or other suitable means.
[0017] The rotatable shaft 20 includes a section 10, which rotates
as substantially one body with the rotatable shaft 20. The section
10 is, for example, affixed to or integral with the rotatable shaft
20. The section 10 includes a surface portion 30 with a surface
that may be parallel to the axis of rotation A. The section 10
further may include axial ends 40 that are perpendicular to the
axis of rotation A of the rotatable shaft 20.
[0018] The section 10 of the rotatable shaft 20 has a generally
circular cross-section. The circular cross-section of the section
10, however, may be non-uniform. In some aspects, the section 10 is
eccentric (i.e., non-concentric) relative to the axis of rotation A
of the rotatable shaft 20. The profile of the section 10 depends on
the particular application of the section 10 and the rotatable
shaft 20.
[0019] In some aspects, the section 10 is a lobe for a rotatable
shaft 20, such as a camshaft for an engine. In other aspects, the
section 10 is a journal or other type of bearing for a rotatable
shaft 20. The section 10 and the rotatable shaft 20 are composed of
materials such as cast iron, cast steel, forged steel, aluminum or
other materials suitable for their application.
[0020] During operation of the rotatable shaft 20, the section 10
may suffer wear and/or become damaged. For example, wear or damage
may occur in situations when inadequate lubrication, misalignment,
or another failure occurs that affects the working interface
between the section and another component or in general, any
follower component contacting the section. Excessive operation may
result in a worn section 10 as well. Such conditions can require
replacement and scrapping of the rotatable shaft 20. The rotatable
shaft 20, however, may advantageously be repaired by the disclosed
process as described below.
[0021] The disclosure provides various aspects for a process
associated with repairing a section 10 of a rotatable shaft 20 that
is worn or damaged to avoid scrapping the rotatable shaft 20 in
favor of a new one. FIG. 2 illustrates a flowchart of a process 100
for repairing a section 10 of a rotatable shaft 20 according to one
aspect of the disclosure. At process 110, a well region 50 is
prepared in the worn section 10. A milling process may be employed
to prepare the well region 50. The milling process may be performed
using a key slot cutter or a ball nose end mill. Alternatively, the
well region 50 may be prepared using a grinding process or a
machining process. Preparing the well region 50 requires removing
at least the worn or damaged portion of the section 10 of the
rotatable shaft 20. Additional material, however, may be removed
from the section 10 during process 110. Once process 110 is
completed, the repair process 100 may optionally proceed to process
120 (pre-weld heat treatment) as explained below. Alternatively,
after process 110, the process 100 may omit process 120 and proceed
to process 130 (depositing material in the well region 50) after
process 110 is completed.
[0022] Referring now to FIG. 3, a portion of the section 10 of the
rotatable shaft 20 is shown after the well region 50 has been
prepared in process 110. FIG. 4 illustrates a partial cross-section
view of the section 10 shown in FIG. 3 cut along the axis of
rotation A. As shown, the well region 50 extends downward into the
surface portion 30 and extends throughout the perimeter of the
section 10. The well region 50 has a bottom portion 60 and opposing
sidewalls 70. The bottom portion 60 may be substantially parallel
to the axis of rotation A. Each sidewall 70 extends proximate to
the axial ends 40 and directly adjoins a remaining portion of the
surface portion 30. In some aspects, fillets 80 may be formed
between the bottom portion 60 and the sidewalls 70 to reduce
strain. The well region 50 may have geometries differing from the
one shown in FIGS. 3 and 4. For example, the bottom portion 60 and
the sidewalls 70 may be curved such that the well region 50 is
curved. For example, the well region 50 may have a curved bottom
portion 60 and curved sidewalls 70. The well region 50 may also
have sidewalls 70 that are angled.
[0023] At 120, the section 10 may be pre-weld heat treated to
prepare the well region 50 and the section 10 for subsequent
processes in the repair process 100. This pre-weld heat treatment
occurs after preparing the well region 50 in the section 10
(process 110) and prior to depositing material into the well region
50 (process 130). The pre-weld heat treatment occurs at a high
temperature for a specified period of time to ensure that the
surface of the well region 50 is adequately prepared for depositing
material in the well region 50. This pre-weld heat treatment
process 120 is optional and depends on the welding process used in
process 130, and the type of material deposited into the well
region 50 as well as the material of the section 10 and the
specific application of the section 10. Pre-weld heat treatment
prior to welding may achieve better weld penetration and slow the
cooling process after welding to allow for added stress relief,
reduced material hardening and the like. Once process 120 is
completed, the repair process 100 proceeds to process 130
(depositing material into the well region 50) as explained below.
In lieu of process 120 or in addition to process 120, the well
region may be cleaned and prepared for the next process. This
process may include sanding, sandblasting, grease removal,
grinding, coating removal, and the like.
[0024] At process 130 of the repair process 100, material is
deposited into the well region 50 to fill the well region 50. The
material deposited in process 130 replaces the material that was
removed from the section 10 when the well region 50 was prepared in
process 110. In general, the amount of material deposited in
process 130 may be greater than the amount of material that was
removed from the section 10 in process 110 to prepare the well
region 50. The material deposited in process 130 may be the same or
similar to the material that the section 10 is composed of and
includes materials such as iron, steel, aluminum, stainless steel,
titanium, nickel or other suitable materials for a section 10 of a
rotatable shaft 20. The material deposited may also include
titanium-based alloys, nickel-based alloys such as Inconel.RTM. and
other alloys. Powder or wire feedstock may be used as the source of
material to be deposited. In some aspects according to the
disclosure, steel powder or steel wire is used as feedstock for the
material deposited.
[0025] Process 130 may be carried out using at least one of the
following welding processes: Laser Beam (LB) Welding, Plasma
Transfer Arc (PTA) Welding, Electron Beam (EB) Welding, Metal Inert
Gas (MIG) Welding, Tungsten Inert Gas (TIG) Welding, or any other
suitable welding processes. These welding processes can be carried
out under an inert gas atmosphere, with inert gas shielding, or
under vacuum to prevent excessive oxidation. For example, argon,
carbon dioxide, helium gas or the like may be provided with some of
aforementioned welding processes. In one aspect according to the
disclosure, Laser Beam (LB) Welding is used in process 130 to
deposit material into the well region 50. In yet another aspect,
argon gas is used with Laser Beam (LB) Welding in process 130 to
deposit material into the well region 50. Laser Beam (LB) Welding,
however, may be performed with other protective gases such as
carbon dioxide or helium. Of course, process 130 may be implemented
without any specialized inert gas atmosphere.
[0026] Process 130 may be performed using multiple consecutive
passes as necessary to fill the well region 50 with deposited
material. Once process 130 has been completed, the repair process
100 may optionally proceed to process 140 (post-weld heat
treatment) as explained below. Alternatively, the repair process
100 may omit process 140 and directly proceed to process 150
(displacing a portion of the deposited material) after process 130
is completed.
[0027] At process 140, the section 10 of the rotatable shaft 20 may
be post-weld heat treated to relieve stress or the like. This
post-weld heat treatment process 140 occurs after depositing
material in the well region 50 (process 130) and prior to
displacing a portion of the deposited material (process 150). The
post-weld heat treatment process 140 is similar to a post-weld heat
treatment that is well known to those skilled in the art. In the
post-weld heat treatment process 140, the section 10 of the
rotatable shaft 20 is typically heated at a high temperature for a
specified period of time. This post-weld heat treatment process 140
is optional but in some instances may substantially reduce the risk
that the section 10 and the rotatable shaft 20 will crack after
welding. The post-weld heat treatment may have some other benefits
as well. In some instances, this post-weld heat treatment process
140 depends on the welding process used in process 130, the
specific application of section 10, and the type of material
deposited into the well region 50. Once process 140 is completed,
the repair process 100 proceeds to process 150 (displacing a
portion of the deposited material) as explained below.
[0028] At process 150 of the repair process 100, a portion of the
material deposited in the well region 50 is displaced. A grinding
process can be used to displace a portion of the material
deposited. Alternatively, a milling or machining process may be
used to displace a portion of the material deposited in the well
region 50. Process 150 is performed until all of the excess
material that was deposited in the well region during process 130
is removed and the section 10 of the rotatable shaft 20 is returned
to its original or desired shape. In some aspects, the section is
polished after the grinding process. Once process 150 is complete,
the repair process 100 is also complete and the section 10 of the
rotatable shaft 20 is considered repaired and ready for use. It
should be noted that process 140 may be implemented after process
150 as well.
[0029] FIG. 5 is a graphical representation of the disclosed
process 100 of repairing the section 10 of the rotatable shaft 20.
As shown in FIG. 5, 500 represents the section 10 of the rotatable
shaft 20 that is worn and in need of repair. As shown in 500, there
are slight indentations or scuff marks imparted to the outer
surface of the section 10. Further shown in FIG. 5, 502 represents
the section 10 of the rotatable shaft 20 after process 110
(preparing a well region 50) and prior to process 130 (depositing
material into the well region 50). As shown in 502, the
indentations and scuff marks are no longer present in the section
10 and the well region 50 has been prepared. As further shown in
FIG. 5, 504 represents the section 10 of the rotatable shaft 20
after process 130 (depositing material into the well region 50) and
prior to process 150 (displacing a portion of the deposited
material). As shown in 504, the well region 50 has been filled with
the deposited material. Next, 506 represents the section 10 of the
rotatable shaft 20 after process 150 (displacing a portion of the
deposited material). As shown in 506, the profile of the section 10
has been reformed and the section 10 is now fully repaired and the
rotatable shaft 20 is ready to be returned to service.
[0030] FIG. 6 is a combustion engine having components that may be
repaired utilizing the disclosed process. Referring to FIG. 5, an
internal combustion engine 601 includes one or more shafts that may
be repaired according to an aspect of the disclosure. The internal
combustion engine 601 may include an engine block 610 and a
turbocharger system 612. The engine block 610 may include a
crankcase within which a crankshaft may be supported. The
crankshaft may be connected to pistons (not shown), which may be
movable within respective cylinders during operation of the engine.
The engine block 610 may further include a camshaft (not shown)
having lobes arranged thereon for valve actuation or the like. The
turbocharger system 612 may include at least one turbocharger
having components that rotate about a shaft. The internal
combustion engine 601 may further include a pump associated with
the cooling system. The cooling system may include a water pump or
coolant pump that may include a shaft. The internal combustion
engine 601 may further include a lubrication system that may
include a lubrication pump or oil pump having a shaft. The internal
combustion engine 601 may further include a hydraulic pump to
provide a source of pressurized hydraulic fluid. The hydraulic pump
may include a shaft. The internal combustion engine may further
include a starter motor having a shaft. The internal combustion
engine 601 may further include a fuel pump. The fuel pump may have
components rotating about a shaft. The internal combustion engine
601 may further include components that include at least one shaft
that may be repaired according to an aspect of the disclosure
including a transmission, drive train, alternator, auxiliary system
and the like.
INDUSTRIAL APPLICABILITY
[0031] The disclosure may find applicability in repairing sections
10 of a wide range of rotatable shafts 20. The process may be
utilized, for example, in any engine or machine that performs some
type of operation associated with industry such as mining,
construction, farming transportation, or any other industry known
in the art.
[0032] The process disclosed herein may be used in applications
such as motor vehicles, machines, locomotives, marine engines,
electrical power generators, small mechanical engines, work
implements, pumps, etc. The rotatable shaft 20 may be used as a
component for a turbine, a turbocharger, a starter, a motor, an
alternator, a water pump, a hydraulic pump, a fuel pump, a coolant
pump, an oil pump, a transmission, an auxiliary system for a
vehicle, and a drivetrain. For example, the section 10 of the
rotatable shaft 20 may be a lobe, a journal or a bearing configured
on a rotatable shaft 20 for a camshaft, a crankshaft, a water pump
shaft, a fuel pump shaft, a coolant pump shaft, etc.
[0033] The disclosed repair process may lead to more efficiently
operating machines and engines because of the quality of the repair
that is achieved. If the section 10 is repaired and the original
shape and profile is restored then the rotatable shaft 20 will be
able to operate in a more efficient manner, ultimately resulting in
an increase operational savings. The disclosed repair process may
also be useful to prolong the life of various rotatable shafts 20
as well as prolonging the life of the machines and engines that use
the repaired rotatable shafts 20. As a result, the disclosed repair
process may lead to concomitant savings in part costs as well as
labor. The process may also result in reducing scrap and therefore,
presenting a greener solution to rotatable shaft 20 repair.
* * * * *