U.S. patent application number 12/930099 was filed with the patent office on 2011-06-09 for process for manufacturing a bearing.
Invention is credited to Gunther HH. von Gynz-Rekowski.
Application Number | 20110131810 12/930099 |
Document ID | / |
Family ID | 44080552 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110131810 |
Kind Code |
A1 |
von Gynz-Rekowski; Gunther
HH. |
June 9, 2011 |
Process for manufacturing a bearing
Abstract
A process for manufacturing a bearing, which may be used in a
tool within a bore hole. The process includes providing a tubular
sleeve, applying a hard facing material on an outer surface of the
tubular sleeve so that the hard facing material is fixed to the
outer surface, and thereafter applying a material layer over the
hard facing material so that the material layer is fixed to the
hard facing material. The process further includes machining the
material layer so that a portion of the material layer is removed,
and then machining the inner surface so that only the hard facing
material is left as an inner surface. The process further includes
machining the inner and outer surfaces to form the bearing. The
process further includes placing the bearing into a housing and
inserting a mandrel into the bearing, where a hard coating of the
mandrel abuts the bearing.
Inventors: |
von Gynz-Rekowski; Gunther HH.;
(Montgomery, TX) |
Family ID: |
44080552 |
Appl. No.: |
12/930099 |
Filed: |
December 28, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11157730 |
Jun 21, 2005 |
7882638 |
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12930099 |
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Current U.S.
Class: |
29/898.04 |
Current CPC
Class: |
Y10T 29/49643 20150115;
F16C 2226/12 20130101; F16C 33/14 20130101; F16C 2226/36 20130101;
F16C 2220/82 20130101; F16C 2220/66 20130101; F16C 2220/62
20130101; B21D 53/10 20130101; F16C 2352/00 20130101; E21B 4/003
20130101; F16C 2220/70 20130101; F16C 2226/14 20130101; F16C
2220/60 20130101 |
Class at
Publication: |
29/898.04 |
International
Class: |
B21K 1/10 20060101
B21K001/10 |
Claims
1. A process for manufacturing a radial bearing for use in a down
hole mud motor, the process comprising the steps of: a) providing a
tubular sleeve having a first inner surface and a first outer
surface; b) fusing a hard facing material on the first outer
surface of the tubular sleeve to form a second outer surface of the
tubular sleeve; c) fusing a material layer on the second outer
surface of the tubular sleeve to form a third outer surface of the
tubular sleeve; d) controlled cooling the hard facing material from
a process temperature of about 3500 degrees Fahrenheit to a
temperature of about 500 degrees Fahrenheit in a material specific
time period in the range of two to five minutes; e) machining the
third outer surface of the tubular sleeve so that a portion of the
material layer is removed; f) machining the first inner surface of
the tubular sleeve to form a second inner surface of the tubular
sleeve, said second inner surface composed of the hard facing
material; g) cutting the length of the tubular sleeve; h) machining
the third outer surface of the tubular sleeve; i) machining the
second inner surface of the tubular sleeve in order to form the
radial bearing; j) placing the radial bearing into a housing; and
k) inserting a mandrel into the radial bearing, said mandrel having
an outer surface, and wherein said outer surface has a hard coating
so that the hard coating of the mandrel abuts the radial
bearing.
2. The process of claim 1 further comprising the step of: d1)
slowly cooling the material layer after the material specific time
period by providing an insulation layer around the third outer
surface of the tubular sleeve.
3. The process of claim 2 wherein in step (d1) the material layer
is cooled to a temperature of 250 degrees Fahrenheit with the
insulation layer around the third outer surface of the tubular
sleeve.
4. The process of claim 1 wherein the tubular sleeve is constructed
of a hard plastic.
5. The process of claim 1 wherein the tubular sleeve is constructed
with a carbon steel, stainless steel, or inconel material.
6. The process of claim 5 wherein the step of fusing the hard
facing material is performed using an oxygen settling process.
7. The process of claim 5 wherein the step of fusing the hard
facing is performed using a laser process.
8. The process of claim 7 wherein the material layer is a soft
carbon steel, stainless steel, or inconel material.
9. The process of claim 8 wherein the hard facing material is a
tungsten carbide, silicon carbide, or ceramic.
10. The process of claim 9 wherein the machining of the second
inner surface in step (i) is performed with a grinder tool.
11. The process of claim 9 wherein in step (g) the tubular sleeve
is cut into a plurality of parts so that a plurality of tubular
sleeves are formed.
12. A process for manufacturing a bearing comprising the steps of:
a) providing a tubular sleeve having a first inner surface and a
first outer surface; b) applying a hard facing material on the
first outer surface of the tubular sleeve so that the hard facing
material is fused onto the first outer surface of the tubular
sleeve to form a second outer surface of the tubular sleeve; c)
applying a material layer on the second outer surface of the
tubular sleeve so that the material layer is fused onto the second
outer surface to form a third outer surface of the tubular sleeve;
d) controlled cooling the hard facing material from a process
temperature of about 3500 degrees Fahrenheit to a temperature of
about 500 degrees Fahrenheit in a material specific time period in
the range of two to five minutes; e) machining the third outer
surface of the tubular sleeve so that a portion of the material
layer is removed; and f) machining the first inner surface of the
tubular sleeve to form a second inner surface, said second inner
surface composed of the hard facing material.
13. The process of-claim 12 further comprising the step of: d1)
slowly cooling the material layer after the material specific time
period by providing an insulation layer around the third outer
surface of the tubular sleeve.
14. The process of claim 13 wherein in step (d1) the material layer
is cooled to a temperature of 250 degrees Fahrenheit with the
insulation layer around the third outer surface of the tubular
sleeve.
15. The process of claim 12 further comprising the step of: g)
cutting the length of the tubular sleeve.
16. The process of claim 15 further comprising the step of: h)
machining the third outer surface of the tubular sleeve.
17. The process of claim 16 further comprising the step of: i)
grinding the second inner surface of the tubular sleeve in order to
form the radial bearing.
18. The process of claim 17 wherein the hard facing material is a
tungsten carbide, silicon carbide, or ceramic.
19. The process of claim 18 wherein the material layer comprises a
ductile carbon steel, stainless steel, or inconel material.
20. The process of claim 15 wherein the controlled cooling of the
tubular sleeve in step (d) includes rapidly cooling the hard facing
material.
21. The process of claim 20 wherein the step of rapidly cooling the
hard facing material further includes forming micro cracks within
the hard facing material.
22. The process of claim 21 further comprising the step of: d1)
slowly cooling the material layer after the material specific time
period.
23. The process of claim 22 wherein step (d1) includes providing an
insulation layer around the third outer surface of the tubular
sleeve.
24. The process of claim 23 wherein step (d1) prevents the
formation of major cracks in the material layer.
25. The process of claim 24 wherein in step (d1) the material layer
is cooled to a temperature of 250 degrees Fahrenheit with the
insulation layer around the third outer surface of the tubular
sleeve.
26. A process for manufacturing a wear surface the process
comprising the steps of: a) providing a structure having a first
surface and a second surface, the second surface opposing the first
surface; b) applying a hard facing material on the first surface of
the structure so that the hard facing material is fixed to the
first surface of the structure; c) applying a material layer over
the hard facing material so that the material layer is fixed to the
hard facing material; d) controlled cooling the hard facing
material from a process temperature of about 3500 degrees
Fahrenheit to a temperature of about 500 degrees Fahrenheit in a
material specific time period in the range of two to five minutes,
then slowly cooling the material layer by providing an insulation
layer over the material layer; e) machining the structure so that a
portion of the material layer is removed; and f) machining the
second surface of the structure to expose the hard facing material
in order to form a wear surface.
27. A process for manufacturing an inner wear surface of a radial
bearing for use in a down hole mud motor, the process comprising
the steps of: a) providing a cylindrical member having a first
outer surface; b) applying a hard facing material on the first
outer surface of the cylindrical member so that the hard facing
material is fixed onto the first outer surface of the cylindrical
member to form a second outer surface of the cylindrical member; c)
applying a material layer on the second outer surface of the
cylindrical member so that the material layer is fixed onto the
second outer surface of the cylindrical member to form a third
outer surface of the cylindrical member; d) controlled cooling the
hard facing material from a process temperature of about 3500
degrees Fahrenheit to a temperature of about 500 degrees Fahrenheit
in a material specific time period in the range of two to five
minutes, then slowly cooling the material layer by providing an
insulation layer over the third outer surface of the cylindrical
member; e) machining the third outer surface of the cylindrical
member so that a portion of the material layer is removed; and f)
drilling out the cylindrical member to expose the hard facing
material which forms an inner surface of said cylindrical member in
order to form an inner wear surface of the radial bearing.
28. The process of claim 27 wherein said cylindrical member is a
rod.
29. The process of claim 28 further comprising the steps of: g)
cutting the length of the rod; h) placing the radial bearing into a
housing; and i) inserting a mandrel into the radial bearing, said
mandrel having an outer surface, and wherein said outer surface of
the mandrel has a hard coating so that the hard coating of the
mandrel abuts the inner wear surface of the radial bearing.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This continuation-in-part application claims the benefit of
and priority to U.S. patent application Ser. No. 11/157,730, filed
on Jun. 21, 2005, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a wear surface, hard facing and
process. More specifically, but not by way of limitation, this
invention relates to a bearing used in surface facilities as well
as down hole tools situated in a well bore, and a process for
manufacturing the bearing.
[0003] In the search for oil and gas, operators find it necessary
to drill with a down hole tool that utilizes a down hole motor. As
those of ordinary skill in the art will appreciate, the down hole
motor includes a stationary housing and a concentrically disposed
drive shaft, wherein the drive shaft has attached a bit means for
boring a bore hole. The mandrel is rotated while concentrically
located within the stationary housing. The friction created by the
rotation of the stationary housing relative to the rotating mandrel
can cause significant problems including wear, deformation and
over-heating. Bearings have been developed for use in these tools.
Prior art remedies include use of a coating process about the drive
shaft, as well as the inner diameter of the stationary housing.
Prior art techniques further include use of carbide inserts as well
as using standard roller and ball bearing technology.
[0004] At least two prior art coating processes are available,
namely the adhesion process and the fusion process. Generally, the
fusion process is more reliable than the adhesion process because
when fusion occurs, the coating material melts into the carrier
metal. One inexpensive adhesion process is spray coating, wherein
the coating material bonds to the carrier material only due to
adhesion force. There are several commercial adhesion process
applications available.
[0005] As those of ordinary skill in the art will recognize, the
fusion process requires significant temperature to melt the surface
of materials. Thus, large spray heads and large heating sources are
required, and wherein these space limitations make it very
impractical for the fusion of inner diameter surfaces such as
required for the down hole motors.
[0006] As noted earlier, solid carbide and carbide tiles (or splits
or balls) are also available for bearings, and wherein the solid
carbide and/or carbide tiles are compressed or glued into the inner
diameter of a radial bearing. The solid carbide is very sensitive
to shock loading, and the filler matrix of the tiles is very
sensitive to temperature, which are both problematic.
[0007] Therefore, there is a need for a bearing that can withstand
the high temperature and shock loading of down hole applications.
There is also a need for an efficient and economical bearing for
use with surface equipment and down hole tools. Further, there is a
need for a radial bearing used in mud motors. These and many other
needs will be met by a reading of the following disclosure.
SUMMARY OF THE INVENTION
[0008] A process for manufacturing a bearing is disclosed. The
process comprises providing a tubular sleeve having an inner
diameter and an outer diameter, and applying a hard facing material
on the outer diameter of the tubular sleeve so that the hard facing
material is fused onto the outer diameter of the tubular sleeve.
The process further includes applying a material layer on the outer
diameter of the tubular sleeve so that the material layer is fused
onto the outer diameter, and then machining the outer diameter of
the tubular sleeve so that a portion of the material layer is
removed, and machining the inner diameter of the tubular sleeve so
that only the hard facing material is left as an inner
diameter.
[0009] The process may further comprise cutting the length of the
tubular sleeve, and thereafter machining the outer diameter of the
tubular sleeve. The process may include grinding the inner diameter
of the tubular sleeve in order to form the bearing. In one
preferred embodiment, the hard facing material is selected from the
group consisting of: tungsten carbide, silicon carbide, or
ceramics. Also, the material layer comprises a ductile carbon
steel, in one preferred embodiment.
[0010] The step of applying the hard facing material may include
rapidly cooling the hard facing material, and wherein the step of
rapidly cooling may include cooling the hard facing material (post
application) from approximately 3500 degrees Fahrenheit to
approximately 200 degrees Fahrenheit in roughly two (2) to five (5)
minutes. Additionally, the step of rapidly cooling may further
include forming micro cracks within the hard facing material.
[0011] Also disclosed is a process for manufacturing a radial
bearing for use in a down hole mud motor. The process comprises
providing a tubular sleeve having an inner diameter and an outer
diameter, fusing a hard facing material on the outer diameter of
the tubular sleeve so that the hard facing material is applied onto
the outer diameter of the tubular sleeve, and fusing a material
layer on the outer diameter of the tubular sleeve so that the
material layer is applied onto the outer diameter. The process
further includes machining the outer diameter of the tubular sleeve
so that a portion of the material layer is, removed, and machining
the inner diameter of the tubular sleeve so that only the hard
facing material is left as an inner diameter. The operator could
then cut the length of the tubular sleeve, machine the outer
diameter of the tubular sleeve, and then machine the inner diameter
of the tubular sleeve in order to form the radial bearing. The
process further includes placing the radial bearing into a housing,
and inserting a mandrel into the radial bearing, and wherein the
outer diameter of the mandrel has a hard coating so that the hard
coating of the mandrel abuts the radial bearing. In one preferred
embodiment, the tubular sleeve is constructed with a carbon steel
material, the material layer may be a soft carbon steel, and the
hard facing material is selected from the group consisting of:
tungsten carbide, silicon carbide, or ceramics. Also, the step of
fusing the hard facing is performed using a laser process, in the
most preferred embodiment.
[0012] Also disclosed is a down hole mud motor for rotating a bit
in a well bore. The down hole mud motor comprises a stationary
tubular housing and a radial bearing concentrically disposed within
the tubular housing. The radial bearing is produced by fusing a
first material to an outer surface of a core sleeve, fusing a
second material to the outer surface, and machining the core sleeve
so that the radial bearing comprises the first material and the
second material. The down hole mud motor further comprises an inner
mandrel concentrically disposed within the tubular housing, and
wherein the inner mandrel has a hard coating applied to an outer
diameter of the inner mandrel so that the hard coating and the
radial bearing abut. The inner mandrel is capable of rotating the
bit. In one preferred embodiment, the housing has an opening for
placement of a punch means for punching and removing the radial
bearing from the stationary tubular housing.
[0013] In yet another embodiment, there is disclosed a process for
manufacturing an inner wear surface of a radial bearing for use in
a down hole mud motor. The process comprises providing a
cylindrical member having an outer diameter and applying a hard
facing material on the outer diameter of the cylindrical member so
that the hard facing material is fixed onto the outer diameter of
the cylindrical member. The process further includes applying a
material layer on the outer diameter of the cylindrical member so
that the material layer is fixed onto the outer diameter of the
cylindrical member and machining the outer diameter of the
cylindrical member so that a portion of the material layer is
removed. In preferred embodiment, the cylindrical member is a rod
and the process further comprises drilling out the rod so that only
the hard facing material is left as an inner diameter. The process
further includes cutting the length of the rod, machining the outer
diameter of the tubular sleeve, and grinding the inner diameter of
the tubular sleeve in order to form an inner wear surface of a
radial bearing. The process may further include placing the radial
bearing into a housing, and inserting a mandrel into the radial
bearing, and wherein the mandrel has an outer diameter that has a
hard coating so that the hard coating of the mandrel abuts the
inner wear surface of the radial bearing.
[0014] An advantage of the present invention includes use of an
outer diameter fusion process which eliminates the need for
separate radial bearing systems and components. Another advantage
is that the radial bearing product of the present invention is
stronger and more rugged than prior art bearings. Yet another
advantage is that the coating of the present invention will endure
the severe temperature and shock loads imposed on down hole tools
employed in boring holes in subterranean formations.
[0015] Another advantage of the present invention is that no radial
bearing components are needed other than the housing and mandrel,
which are an integral part of a radial bearing. Thus, a more robust
mandrel and housing can be used since more radial space is
available within the housing. Accordingly, more loading capacity
and better reliability are experienced with the radial bearing of
the present disclosure.
[0016] Yet another advantage is the rapid cooling of the hard
facing material in one embodiment which allows for good particle
distribution. Also, the rapid cooling process allows, in one
preferred embodiment, for the formation of micro cracks in the hard
facing material.
[0017] A feature of the present invention is that the materials
used are applied to the outer diameter of a core sleeve. Another
feature is that the outer diameter of the core sleeve, with the
materials of the present invention applied thereto, can be machined
with conventional tools. Still yet another feature is that the core
sleeve, after application of the various materials, can be machined
from the inner diameter using known milling and grinding tools. A
feature of the present invention is that the starting tubular
sleeve may be of sufficient length that it is possible for the
operator, after the application of the various layers and machining
of the outer and inner diameter, to cut the bearings into several
predetermined lengths so that a plurality of bearings are produced,
which will result in cost savings and lessen the manufacturing
time.
[0018] In another embodiment, a process for manufacturing a radial
bearing for use in a down hole mud motor may include providing a
tubular sleeve having a first inner surface and a first outer
surface and fusing a hard facing material on the first outer
surface of the tubular sleeve to form a second outer surface of the
tubular sleeve. The process may include fusing a material layer on
the second outer surface of the tubular sleeve to form a third
outer surface of the tubular sleeve. The process may include
controlled cooling the hard facing material from a process
temperature of about 3500 degrees Fahrenheit to a temperature of
about 500 degrees Fahrenheit in a material specific time period in
the range of two to five minutes. The third outer surface of the
tubular sleeve may be machined so that a portion of the material
layer is removed, and the first inner surface of the tubular sleeve
may be machined to form a second inner surface of the tubular
sleeve composed of the hard facing material. The process may also
include cutting the length of the tubular sleeve, machining the
third outer surface of the tubular sleeve, machining the second
inner surface of the tubular sleeve in order to form a radial
bearing. The radial bearing may be placed into a housing and a
mandrel may be inserted into the radial bearing. The mandrel may
have an outer surface with a hard coating so that the hard coating
of the mandrel abuts the radial bearing.
[0019] The process may further include slowly cooling the material
layer after the material specific time period by providing an
insulation layer around the third outer surface of the tubular
sleeve. The material layer may cooled to a temperature of 250
degrees Fahrenheit with the insulation layer around the third outer
surface of the tubular sleeve. The tubular sleeve may be
constructed of hard plastic, carbon steel, stainless steel, or
inconel material. The step of fusing the hard facing material may
be performed using an oxygen settling process or a laser process.
The material layer may be a soft carbon steel, stainless steel, or
inconel material. The hard facing material may be a tungsten
carbide, silicon carbide, or ceramic. The step of machining the
second inner surface may be performed with a grinder tool. The
tubular sleeve may be cut into a plurality of parts so that a
plurality of tubular sleeves are formed.
[0020] In another embodiment, a process for manufacturing a bearing
may include providing a tubular sleeve having a first outer surface
and a first inner surface, applying a hard facing material on the
first outer surface so that the hard facing material is fused onto
the first outer surface to form a second outer surface of the
tubular sleeve, and applying a material layer on the second outer
surface so that the material layer is fused onto the second outer
surface to form a third outer surface of the tubular sleeve. The
process may include controlled cooling the hard facing material
from a process temperature of about 3500 degrees Fahrenheit to a
temperature of about 500 degrees Fahrenheit in a material specific
time period in the range of two to five minutes. The third outer
surface of the tubular sleeve may be machined so that a portion of
the material layer is removed, and the first inner surface of the
tubular sleeve may be machined to form a second inner surface
composed of the hard facing material.
[0021] The process may further include slowly cooling the material
layer after the material specific time period by providing an
insulation layer around the third outer surface of the tubular
sleeve. The material layer may cooled to a temperature of 250
degrees Fahrenheit with the insulation layer around the third outer
surface of the tubular sleeve. The process may further include
cutting the length of the tubular sleeve, machining the third outer
surface of the tubular sleeve, and grinding the second inner
surface of the tubular sleeve in order to form the radial bearing.
The hard facing material may be tungsten carbide, silicon carbide,
or ceramic. The material layer may be a ductile carbon steel,
stainless steel, or inconel material. The controlled cooling of the
tubular sleeve may include rapidly cooling the hard facing material
which may involve forming micro cracks within the hard facing
material. The process may further include slowly cooling the
material layer after the material specific time period. The step of
slowly cooling the material layer may include providing an
insulation layer around the third outer surface of the tubular
sleeve. The material layer may cooled to a temperature of 250
degrees Fahrenheit with the insulation layer around the third outer
surface of the tubular sleeve. The step of slowly cooling the
material layer may prevent the formation of major cracks in the
material layer.
[0022] In yet another embodiment, a process for manufacturing a
wear surface may include providing a structure having a first
surface and a second surface opposing the first surface, applying a
hard facing material on the first surface so that the hard facing
material is fixed to the first surface, and applying a material
layer over the hard facing material so that the material layer is
fixed to the hard facing material. The process may also include
controlled cooling the hard facing material from a process
temperature of about 3500 degrees Fahrenheit to a temperature of
about 500 degrees Fahrenheit in a material specific time period in
the range of two to five minutes, then slowly cooling the material
layer by providing an insulation layer over the material layer. The
process may further include machining the structure so that a
portion of the material layer is removed, and machining the second
surface of the structure to expose the hard facing material in
order to form a wear surface.
[0023] In still another embodiment, a process for manufacturing an
inner wear surface of a radial bearing for use in a down hole mud
motor may include providing a cylindrical member having a first
outer surface, applying a hard facing material on the first outer
surface so that the hard facing material is fixed onto the first
outer surface to form a second outer surface of the cylindrical
member, and applying a material layer on the second outer surface
so that the material layer is fixed onto the second outer surface
to form a third outer surface of the cylindrical member. The
process may include controlled cooling the hard facing material
from a process temperature of about 3500 degrees Fahrenheit to a
temperature of about 500 degrees Fahrenheit in a material specific
time period in the range of two to five minutes, then slowly
cooling the material layer by providing an insulation layer over
the third outer surface of the cylindrical member. The process may
also include machining the third outer surface of the cylindrical
member so that a portion of the material layer is removed, and
drilling out the cylindrical member to expose the hard facing
material which forms an inner surface of the cylindrical member in
order to form an inner wear surface of the radial bearing. The
cylindrical member may be a rod. The process may further include
cutting the length of the rod, placing the radial bearing into a
housing, and inserting a mandrel into the radial bearing. The outer
surface of the mandrel may have a hard coating so that the hard
coating of the mandrel abuts the inner wear surface of the radial
bearing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a cross-sectional view of a core sleeve of the
present invention.
[0025] FIG. 2 is a cross-sectional view of the core sleeve of FIG.
1 with a first coating applied thereto.
[0026] FIG. 3 is a cross-sectional view of the core sleeve of FIG.
2 with a second coating applied thereto.
[0027] FIG. 4 is a cross-sectional view of the core sleeve of FIG.
3 having been machined on the outer diameter.
[0028] FIG. 5 is a cross-sectional view of the core sleeve of FIG.
4 having been machined on the inner diameter.
[0029] FIG. 6 is a cross-sectional view of the core sleeve of FIG.
5 having been machined on the outer diameter.
[0030] FIG. 7 is a cross-sectional view of the core sleeve of FIG.
6 having been machined on the inner diameter.
[0031] FIG. 8 is a partial cross-sectional view of the core sleeve
of FIG. 7 concentrically disposed within a housing of a mud
motor.
[0032] FIG. 9 is a partial cross-sectional view of a mandrel with a
hard coating applied to the outer diameter.
[0033] FIG. 10 is a partial cross-sectional view of the mandrel
within the housing of a mud motor.
[0034] FIG. 11A is a schematic illustration of a preferred
embodiment of the hard facing material and the material layer which
had undergone a controlled and rapid cooling.
[0035] FIG. 11B is a schematic illustration of the one embodiment
of the hard facing material and the material layer which had not
undergone rapid cooling.
[0036] FIG. 11C is a schematic illustration of the one embodiment
of the hard facing material and the material layer which had not
undergone controlled applying and cooling.
[0037] FIG. 12 is a schematic illustration of the micro cracks
formed in the hard facing material after rapid cooling.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] Referring now to FIG. 1, a cross-sectional view of a core
sleeve 2 of the present invention is shown. The core sleeve 2 is
made up from easy weldable and machinable material such as carbon
steel in the preferred embodiment. The core sleeve 2 can also be
constructed of a hard plastic. The core sleeve 2 has an outer
diameter surface 4 and an inner diameter surface 6. As will be more
fully set out, it is important to retain an accurate measurement of
the outer diameter surface 4.
[0039] FIG. 2 is a cross-sectional view of the core sleeve 2 of
FIG. 1 with a first coating applied thereto. More specifically, the
operator will apply a layer of hard facing to the outer diameter
surface 4. In the most preferred embodiment, the fusion process is
utilized. An oxygen settling process or a laser process, both of
which are commercially available, can be utilized in this hard
facing step. In the most preferred embodiment, the laser process is
utilized as set out below. Also in the most preferred embodiment,
the hard facing material can be selected from the group consisting
of tungsten carbide, silicon carbide or ceramics, all of which are
commercially available. In the most preferred embodiment, tungsten
carbide is used, and is commercially available. Thus, the hard
facing material does not have to be heated up above temperatures
that would change the mechanical property of the core or carrier
sleeves. Also, very hot application temperatures can cause cracks
in the structure (of the hard facing material) of the wear
particles.
[0040] As noted earlier, in the most preferred embodiment, a laser
assisted procedure with inert gas coverage is used to apply the
hard facing, and the temperature should not exceed 3500 degrees
Fahrenheit. It should be noted that it is also possible to use a
high velocity oxygen fuel process system (HVOS) in order to apply
the hard facing to the outer diameter surface 4. Both the HVOS and
the laser assisted procedure is commercially available. The hard
facing application in effect generates a new outer diameter surface
8.
[0041] Referring now to FIG. 3, a cross-sectional view of the core
sleeve 2 of FIG. 2 with a second coating applied thereto will now
be described. More specifically, the process would include applying
a layer of metal (material layer) on the top of the previously
applied hard facing surface 8. Thus, a new outer diameter surface
10 is formed. In this step, the operator applies a layer of metal
on top of the hard facing. In the most preferred embodiment, the
same process that was used for applying the hard facing is used in
the step shown in FIG. 3. Also, the same set up is used, namely a
laser assisted procedure with inert gas coverage while not going
over temperatures above 3500 degrees Fahrenheit. The metal should
have high ductility and medium yield i.e. soft carbon steel. In the
most preferred embodiment, the metal used in FIG. 3 is commercially
available.
[0042] FIG. 4 is a cross-sectional view of the core sleeve 2 of
FIG. 3 having been machined on the outer diameter 10. In the
preferred embodiment, a commercial lathe can be used. It is
important to keep as close as possible to a cylindrical shape.
Hence, this first cut is referred to as rough since it is important
to get a cylindrical shape so that the inner diameter can be
measured and machined, as will be discussed in more detail.
[0043] Referring now to FIG. 5, a cross-sectional view of the core
sleeve 2 of FIG. 4 having been machined on the inner diameter 6
will now be described. A commercially available lathe can also be
used. Hence, the operator will utilize known techniques to machine
out the inner diameter 6 to a specific dimension, the specific
dimension depending on the specific size mud motor used, thereby
exposing a new inner diameter surface 12. Additionally, the core
sleeve 2 is cut to a specific length L, wherein the length L
corresponds to the mud motor dimension as will be more fully set
out later in the disclosure. The type of tool used to cut the
length may be a commercially available saw. It should be noted that
it is within the teachings of this invention that the starting
tubular sleeve may be of sufficient length that it is possible for
the operator, in this step, to cut several bearings to a
predetermined length from this single piece. In other words, the
finished bearing of FIG. 5 may be cut into a plurality of bearings
so that several bearings are produced, which will save on
manufacturing cost and improve time efficiency.
[0044] In FIG. 6, the cross-sectional view of the core sleeve 2 of
FIG. 5 having been machined on the outer diameter surface 10 to the
specific dimensions and tolerances of the mud motor is shown.
Therefore, FIG. 6 depicts a new outer diameter surface 14 having
been exposed through machining. A commercially available lathe may
be used in this step. Referring now to FIG. 7, a cross-sectional
view of the completed bearing, which is represented by the numeral
15. Hence, bearing 15 is the core sleeve 2 of FIG. 6 having been
machined on the inner diameter thereby producing a new inner
diameter surface 16. In the most preferred embodiment, this cut is
the final machine to the inner diameter area to given
specifications and tolerances. The type of tool used to machine the
inner diameter, in one preferred embodiment, is a grinding type of
tool well known in the art. The steps illustrated in FIGS. 4
through 7 represent the most preferred embodiment of manufacturing
the bearing 15 and were done in this specific order, and wherein
this specific order has been shown by experimentation to prevent
deformation of the bearing 15 due to residual stress generated when
machining. Another option to reduce residual stress caused when
machining is a controlled heat stress relieve process which entails
controlled heating and cooling procedures of the bearing.
[0045] Referring now to FIG. 8, a partial cross-sectional view of
the bearing 15 of FIG. 7 concentrically disposed within a lower
housing 20 of a mud motor is illustrated. The bearing 15 is a
product made by the process illustrated in steps of FIGS. 1 through
7. The bearing 15 is press fitted in the most preferred embodiment
into the inner bore 22 of the lower housing 20. It should be noted
that it is also possible to utilize heat shrinking or welding of
the bearing 15 into the inner bore portion 22 of the lower housing
20. All these processes are commonly used and known throughout the
industry. The combination of the outer radial bearing female 15
placed in the lower housing 20 with the mandrel (that will be
described in the discussion of FIG. 9) provides a complete radial
bearing assembly means of the present invention.
[0046] Returning to FIG. 8, the lower housing 20 contains an outer
surface 24, which is generally cylindrical. The inner bore portion
22 contains a first inner diameter portion 26 that extends to a
second inner diameter portion 28, and wherein the inner bore
portion 22 contains the radial shoulder 30. The end 32 of the
bearing 15 will abut the radial shoulder 30. The lower housing 20
has an opening 33a for placement of punch means 33b for punching
and removing the bearing. For instance, the operator may find it
desirable to remove and replace the bearing, and therefore, the
operator can utilize the punch 33b via opening 33a to crimp the
radial bearing and remove as appropriate.
[0047] FIG. 9 is a partial cross-sectional view of a mandrel 34
with a hard coating 36 applied to the first outer diameter surface
38. The mandrel 34 may also be referred to as the drive shaft 34.
The hard coating 36 is applied to the outer diameter surface 38
using known techniques of applying metal material, as was discussed
with reference to FIG. 2 above. Returning to FIG. 9, the first
outer diameter surface 38 extends to a second outer diameter
surface 40, which is an enlarged cylindrical surface. Extending
radially inward is the inner bore 42. Generally, the mandrel 34 is
the rotational component of the mud motor, and the mandrel 34 can
be attached to a bit means, as will be more fully explained later
in the application.
[0048] Referring now to FIG. 10, a partial cross-sectional view of
the mandrel 34 within the lower housing 20 of a mud motor 44 will
now be described. As will be appreciated by those of ordinary skill
in the art, mud motors are commercially available from several
vendors, and are attached to a drill string 45. For instance, Baker
Hughes Inc. has a commercially available mud motor under the name
Navi Drill. FIG. 10 depicts the lower housing 20 being connected to
an upper housing 46, and wherein the drive shaft 34 (i.e. mandrel
34) is disposed therein. The bearing 15 is shown disposed within
the lower housing 20 and wherein the bearing 15 will cooperate with
the hard coating 36 of the drive shaft 34. The lower housing 20 and
the upper housing 46 is collectively referred to as the housing.
With the drive shaft 34 disposed within the housing, a cavity is
formed, and wherein the thrust bearing 48 is disposed therein. The
purpose of the thrust bearing 48 is to transmit the axial load from
the drill string via drive shaft 34 to the bit 50.
[0049] As understood by those of ordinary skill in the art, the
circulation of drilling fluid down the inner portion of the drill
string, and through the mud motor 44, will cause the drive shaft 34
to rotate. The drive shaft 34 will be connected to a bit means 50
for boring a bore hole 52. The purpose of the radial bearing is to
allow rotation of the drive shaft 34 relative to the lower housing
20, to clutch radial forces and to allow stabilization of the drive
shaft relative to the lower housing 20 while minimizing the
friction forces. Operators find it desirable to design the mud
motors to rotate at 100 to 300 revolutions per minute. Hence,
having a bearing section is critical. The present invention allows
for an economical and efficient bearing assembly, with a long life
as compared to prior art bearing assemblies.
[0050] Referring now to FIG. 11A, a partial schematic illustration
of a preferred embodiment of the hard facing material 60 and the
material layer 62, which have been applied according to the
teachings of the present invention, as set out in FIGS. 1 thru 7.
Additionally, the hard facing material 60 has undergone rapid
cooling after application. More specifically, FIG. 11A depicts the
particulate material 64 suspended within the filler material (seen
generally at 66). The particulate material 64 may be a carbide and
the filler material may be a cobalt or nickel composition, both
being commercially available and well known in the art. The hard
facing material 60, which may also be referred to as the wear
surface 60, is the surface that will abut the mandrel. Therefore,
the wear surface 60 bears the rotational and radial force
(including friction) of the moving components. The material layer
62 will bear the stress imposed during operation. For instance, in
the mud motor application, the material layer 62 will bear the
normal stress, shear stress, radial stress, etc.
[0051] FIG. 11A depicts a good distribution of the particulate
material. As understood by those of ordinary skill in the art, the
hard facing material is applied at temperatures in the 3500 degree
Fahrenheit range. One of the methods of obtaining good particle
distribution is to rapidly cool the hard facing material after
controlled application. In other words, the hard facing material is
not allowed to cool normally, but rather is rapidly cooled so that
the particles are not allowed to settle. This is done by fast
cooling which includes cooling the hard facing, material from a
temperature of 3500 degrees Fahrenheit (immediately after
application) to a temperature of approximately 500 degrees
Fahrenheit in approximately 2 to 5 minutes. Continued rapid cooling
beyond this point could result in major cracks in the material
layer 62 which could result in portions of the material layer 62
breaking off from the hard facing material. Instead, after the
rapid cooling, the material layer 62 may be wrapped or otherwise
covered with a layer of insulation and allowed to cool slowly. The
material layer may be slowly cooled to a temperature of 250 degrees
Fahrenheit with the layer of insulation around the material layer
62. More preferably, the material layer may be slowly cooled to a
temperature of 200 degrees Fahrenheit in this manner. In an
alternate embodiment, the material layer may be cooled to ambient
temperature in this manner. This subsequent slow cooling step will
help to prevent major cracks in the material layer 62 while
achieving good particle distribution in the hard facing material
60. The layer of insulation may be formed of any insulating
material. For example, a heat blanket may be used as the insulation
layer.
[0052] FIG. 11B is a partial schematic illustration of one
embodiment of the hard facing material and the material layer,
wherein the hard facing material had not undergone rapid cooling.
In the embodiment seen in FIG. 11B, the particle distribution is
poor. This poor distribution was caused by improper cooling.
Referring now to FIG. 11C, a schematic illustration of another
embodiment of the hard facing material and the material layer,
wherein the hard facing material has not been applied in a
controlled manner. In FIG. 11C, the particle distribution is poor.
This poor distribution was caused by improper cooling, and an
improper mixture of the filler material. Thus, according to the
teachings of the present invention, the rapid cooling of the hard
facing material 60 and the subsequent slow cooling of the material
layer 62 will allow for good particle distribution in the hard
facing material 60 and will prevent major cracks in the material
layer 62, thereby allowing the hard facing material 60 and the
material layer 62 to assist its load and wear function of the
bearing.
[0053] FIG. 12 is a schematic illustration of the micro cracks
formed in the hard facing material after rapid cooling, according
to one preferred embodiment. The micro cracks are represented by
the diagonal lines traversing FIG. 12. The micro cracks, such as
seen at 68, are introduced into the hard facing material 60 by the
rapid cooling. The micro cracks makes the hard facing material
flexible. At the same time, the hard facing material 60 is not
allowed to chip and fall off. Hence, the hard facing material 60 is
flexible, but does not fall off.
[0054] While preferred embodiments of the present invention have
been described, it is to be understood that the embodiments
described are illustrative only and that the scope of the invention
is to be defined solely by the appended claims when accorded a full
range of equivalence, many variations and modifications naturally
occurring to those skilled in the art from a review thereof.
* * * * *