U.S. patent application number 12/546902 was filed with the patent office on 2009-12-24 for ultrasonic testing of fitting assembly.
This patent application is currently assigned to SWAGELOK COMPANY. Invention is credited to Richard A. Ales, William H. Glime, John Barry Hull, Jeffrey M. Rubinski, Michael Douglas Seymour, Peter C. Williams, Wenxian Yang.
Application Number | 20090314087 12/546902 |
Document ID | / |
Family ID | 29736633 |
Filed Date | 2009-12-24 |
United States Patent
Application |
20090314087 |
Kind Code |
A1 |
Ales; Richard A. ; et
al. |
December 24, 2009 |
ULTRASONIC TESTING OF FITTING ASSEMBLY
Abstract
Apparatus and method for determining relative and/or absolute
axial position of a conduit end within a fluid coupling includes
application of input ultrasonic energy in the form of transient
shear waves and analyzing the reflected energy. Application of the
input energy collected at different radial positions about a first
axial location is used with wavelet based correlation techniques to
better analyze the reflected energy signals. Quality of the
abutment between the conduit end and a surface associated with the
coupling may also be determined as a separate or combined feature
of the axial position determination.
Inventors: |
Ales; Richard A.; (Mentor,
OH) ; Glime; William H.; (Painesville, OH) ;
Hull; John Barry; (Leicestershire, GB) ; Rubinski;
Jeffrey M.; (Wickliffe, OH) ; Seymour; Michael
Douglas; (Cotgrave, GB) ; Williams; Peter C.;
(Cleveland Heights, OH) ; Yang; Wenxian; (Dunkirk,
GB) |
Correspondence
Address: |
CALFEE HALTER & GRISWOLD, LLP
800 SUPERIOR AVENUE, SUITE 1400
CLEVELAND
OH
44114
US
|
Assignee: |
SWAGELOK COMPANY
Solon
OH
|
Family ID: |
29736633 |
Appl. No.: |
12/546902 |
Filed: |
August 25, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11876150 |
Oct 22, 2007 |
7591181 |
|
|
12546902 |
|
|
|
|
10518337 |
Dec 15, 2004 |
7284433 |
|
|
PCT/US03/19133 |
Jun 17, 2003 |
|
|
|
11876150 |
|
|
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|
60389394 |
Jun 17, 2002 |
|
|
|
Current U.S.
Class: |
73/597 |
Current CPC
Class: |
G01N 29/11 20130101;
G01N 29/46 20130101; G01N 2291/2691 20130101; G01N 2291/0422
20130101; G01N 2291/044 20130101; G01N 29/2462 20130101; G01N
29/2468 20130101; G01N 29/28 20130101; G01N 2291/2634 20130101;
G01N 2291/02491 20130101; G01N 29/043 20130101; G01N 2291/0423
20130101; G01N 2291/056 20130101 |
Class at
Publication: |
73/597 |
International
Class: |
G01N 29/04 20060101
G01N029/04 |
Claims
1. A method for evaluating a pulled-up condition of a fitting of
the type having a conduit assembled at one end to a fitting
comprising a body, a nut, and a conduit gripping device, the method
comprising the steps of: pulling up the fitting on the conduit to
form a fitting assembly wherein the conduit gripping device forms
an impression on the conduit; applying mechanical energy into the
fitting assembly at a reference position; detecting at said
reference position return mechanical energy; and determining
whether the conduit gripping device is correctly installed based on
axial position of said impression relative to said reference
position.
2. The method of claim 1 comprising two conduit gripping
devices.
3. The method of claim 2 wherein said conduit gripping devices
comprise a front ferrule and back ferrule.
4. The method of claim 1 wherein the conduit, nut, body and conduit
gripping device are formed from stainless steel.
5. The method of claim 1 wherein said impression comprises a
deformation formed by the conduit gripping device biting into the
conduit.
6. The method of claim 1 wherein said impression comprises a
deformation of the conduit from a compression of the conduit
gripping device against the conduit after pull-up.
7. Apparatus for evaluating a fitting for conduits, the apparatus
comprising: a fitting comprising a first component, a second
component and at least one conduit gripping device; a conduit
assembled with the fitting to form a pulled-up fitting assembly,
wherein the conduit gripping device forms an impression on the
conduit after the fitting has been pulled-up; first means to apply
mechanical energy into the fitting assembly and to detect returned
energy and produce a signal related thereto; and second means to
determine axial position of the impression on the conduit based on
said signal.
8. The apparatus of claim 7 wherein said first means comprises a
transducer.
9. The apparatus of claim 8 wherein said transducer operates as
both a source of the mechanical energy and a receiver of the
mechanical energy.
10. The apparatus of claim 7 wherein said first means comprises an
ultrasonic transducer.
11. The apparatus of claim 7 wherein said conduit gripping device
comprises a ferrule.
12. The apparatus of claim 7 wherein the first component comprises
a nut and the second component comprises a body, said nut and body
being threadably joined together in the pulled up fitting
assembly.
13. The apparatus of claim 12 wherein the conduit, body, nut and
conduit gripping device comprise stainless steel.
14. Apparatus for evaluating a fitting for conduits, the apparatus
comprising: a fitting comprising a first component, a second
component and at least one conduit gripping device; a conduit
assembled with the fitting to form a fitting assembly, wherein the
conduit gripping device forms an impression on the conduit after
the fitting has been pulled-up; first means to apply mechanical
energy into the fitting assembly and to detect return mechanical
energy and produce a signal related thereto; and second means to
determine whether the conduit gripping device is correctly
installed based on said signal.
15. The apparatus of claim 14 wherein said mechanical energy
comprises ultrasonic energy.
16. Apparatus for evaluating a fitting for conduits, the apparatus
comprising: a fitting comprising a first component, a second
component and at least one conduit gripping device; a conduit
assembled to the fitting to form a fitting assembly, wherein the
conduit gripping device forms an impression on the conduit after
the fitting has been pulled-up; a source adapted to apply
mechanical energy into the fitting assembly; a receiver adapted to
detect return mechanical energy and produce a signal related
thereto; and an analyzer that determines whether the conduit
gripping device is correctly installed based on said signal.
17. A method for evaluating a pulled-up condition of a fitting of
the type having a conduit assembled at one end to a fitting
comprising a body, a nut, and a conduit gripping device, the method
comprising the steps of: pulling up the fitting on the conduit to
form a fitting assembly wherein the conduit gripping device forms
an impression on the conduit; applying mechanical energy into the
fitting assembly; detecting return mechanical energy and producing
a signal related thereto; and determining whether the conduit
gripping device is correctly installed based on said signal.
18. The method of claim 17 wherein said mechanical energy comprises
ultrasonic energy waves.
19. A method for evaluating a pulled-up condition of a fitting of
the type having a conduit assembled at one end to a fitting
comprising a body, a nut, and a conduit gripping device, the method
comprising the steps of: pulling up the fitting on the conduit to
form a fitting assembly wherein the conduit should have a
deformation at an expected axial position on the conduit caused by
compression of the gripping device when correctly installed;
applying mechanical energy into the fitting assembly; detecting
return mechanical energy; and determining whether the conduit
gripping device is correctly installed based on the presence or
absence of the deformation of the conduit at the expected axial
position.
20. The method of claim 19 wherein said deformation comprises one
or both of a bite and radial compression of the conduit gripping
device against the conduit.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
11/876,150 filed Oct. 22, 2007 for ULTRASONIC TESTING OF FITTING
ASSEMBLY which is a continuation of U.S. Ser. No. 10/518,337 filed
on Dec. 15, 2004, now U.S. Pat. No. 7,284,433, issued on Oct. 23,
2007, for ULTRASONIC TESTING OF FITTING ASSEMBLY FOR FLUID CONDUITS
WITH A HAND-HELD APPARATUS, which is a national phase entry under
35 U.S.C. .sctn.371 and claims priority to International
Application No. PCT/US2003/19133, with an International Filing Date
of Jun. 17, 2003, for ULTRASONIC TESTING OF FITTING ASSEMBLY. which
claims the benefit of U.S. Provisional patent application Ser. No.
60/389,394 filed on Jun. 17, 2002 for ULTRASONIC FITTING ASSEMBLY
VALIDATION, the entire disclosure of which is fully incorporated
herein by reference.
TECHNICAL FIELD OF THE INVENTION
[0002] The invention relates generally to apparatus and methods for
non-destructive evaluation of fitting assemblies after assembly is
completed. More particularly, the invention relates to using
mechanical energy to make evaluations of the fitting assembly.
BACKGROUND OF THE INVENTION
[0003] Fluid handling equipment, whether the fluid is gas, liquid,
combination of gas and liquid, slurries and so on, may use many
fluid control devices that are connected together with the use of
fittings. Typical fluid control devices include valves, regulators,
meters and so on that are interconnected in a fluid circuit with
either tube or pipe. The fittings may take on a wide variety of
designs, including but not limited to single ferrule and
multi-ferrule tube fittings, various clamping arrangements using
elastomeric seals, gripping rings and so on. For purposes of this
disclosure we refer to tube and pipe as "conduit" because the
present invention may be used with either tube or pipe.
[0004] Common to nearly all fluid circuits that use fittings to
connect conduit to a flow control device or process is the desire
to verify in a non-destructive manner that a fitting has been fully
assembled. Most connections via fittings involve the positioning of
a conduit within a fitting body or other structure associated with
a fluid coupling (referred to herein as a fitting assembly of a
conduit and coupling) such that an end of the conduit abuts a
shoulder or wall of the fitting body or other structure. This
abutment or "bottoming" as we also refer to it herein, is usually
desirable as it allows that gripping device, such as a ferrule, to
be installed onto the conduit without the conduit moving
axially.
[0005] Inherent in the assembly process, however, is the practical
circumstance that once the fitting is installed there is no
cost-effective non-destructive way, known to date, to determine
that the conduit is fully bottomed. For example, it is known to use
x-rays to observe the fitting condition, however, this is a very
expensive process and simply not practical for many if not most
assemblers. Various techniques are known that are used to verify
proper installation of the fitting components, or to verify proper
pull-up based on the number of turns of a fitting nut or axial
displacement of the conduit relative to the nut. For example, the
fitting may be disassembled after pull-up, visually inspected and
then reassembled, but such steps are time consuming and costly. In
another known technique, the tubing may be pre-marked in an
appropriate manner prior to assembly, but this technique is subject
to error in the marking or interpretation process. None of these
techniques can absolutely determine in a final assembled fitting
that the conduit is bottomed, and also determine the nature or
quality of the contact or abutment between the conduit and the
associated structure.
[0006] The need exists therefore to provide process and apparatus
for non-destructive analysis and evaluation of whether a conduit is
properly bottomed within a fitting.
SUMMARY OF THE INVENTION
[0007] The invention contemplates in one aspect determining
position of a conduit end using input energy applied to the
conduit. In one exemplary embodiment, ultrasonic energy emitted
from a shear wave transducer is applied to the conduit and
propagates through the conduit as mechanical waves. Alternatively
or in combination, the input energy may be applied through one or
more of the fluid coupling components such as the fitting body, for
example. Reflected energy (also sometimes referred to herein
alternatively as return signals, return energy, return energy
signals, reflected signals or reflected energy signals) is
converted into electrical signals by the transducer and these
electrical signals are analyzed to determine position of the
conduit end. In a specific exemplary application the invention may
be used to determine the position of an end of the conduit within a
fluid coupling installed thereon. In alternative applications, the
invention may be used to determine proper assembly of one or more
of the ferrules in a single or multi-ferrule tube fitting by
detecting a characteristic of the tube bite or indentation
typically associated with ferrule-type tube fittings, such as, for
example, the axial location thereof or the presence/absence
thereof.
[0008] In accordance with another aspect of the invention,
correlation techniques are used to more clearly discriminate the
reflected energy signals. In one exemplary embodiment, ultrasonic
energy is applied to the conduit at different radial positions
about a first location of the conduit that is axially spaced from
the conduit end. Reflected energy signals are correlated to
determine relative axial position of the conduit end. Noise
reduction may also be applied to the return signals.
[0009] In accordance with another aspect of the invention, the
quality and/or nature of contact between the conduit and a surface
associated with a fluid coupling installed on the conduit end may
be determined. In one exemplary embodiment, ultrasonic energy is
applied to the conduit and the amplitude of reflected energy is
analyzed to determine the quality of the contact or bottoming of
the conduit end against the surface associated with the fluid
coupling, such as, for example, whether the conduit end is fully
bottomed, partially bottomed or not bottomed. Correlation analysis
may also be used in connection with this aspect of the
invention.
[0010] In another embodiment of the invention, a tool is provided
that integrates a source that applies mechanical energy waves, an
analyzer that determines the characteristics of a fitting assembly
as a function of reflected portions of energy waves, or both, with
a gap gauge.
[0011] These and other aspects and advantages of the present
invention will be readily appreciated and understood from the
following detailed description of the invention in view of the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a prior art two ferrule flareless tube fitting as
an exemplary fluid coupling that the present invention may be used
with, illustrated in half-view longitudinal cross-section;
[0013] FIG. 2 is an elevation of a fluid coupling assembly and the
present invention;
[0014] FIG. 3 is a functional block diagram of an analyzer in
accordance with the invention; and
[0015] FIG. 4 is an end view of an optional configuration for an
ultrasonic transducer location in accordance with another aspect of
the invention.
[0016] FIG. 5 is an alternative embodiment wherein a source and/or
an analyzer is integrated with a hand-held tool, such as a gap
gauge.
[0017] FIG. 6 is the tool shown in FIG. 5 implemented through the
fitting neck.
[0018] FIG. 7 is the tool shown in FIG. 6 implemented through the
tube and nut.
[0019] FIG. 8 is an assembly of fittings wherein the tool of FIG. 5
can be implemented.
DETAILED DESCRIPTION OF THE INVENTION
1. Introduction
[0020] The present invention is directed to apparatus and methods
relating to determining position of a conduit within a fluid
coupling installed on the conduit. This determination may include,
separately or combined, determining the axial position of an end of
the conduit within a fluid coupling, and determining the quality of
contact between the conduit and a surface associated with the fluid
coupling.
[0021] Determining the axial position of a conduit within a fluid
coupling is particularly useful, for example, with tube fittings of
the type that have a threadably coupled nut and body and at least
one ferrule that is used to provide a fluid tight coupling between
the tube end and the body. Although the invention is described
herein with particular reference to its use with a two ferrule
flareless tube fitting, those skilled in the art will readily
appreciate that the invention may be used in many other
applications, and generally to any application wherein it is
desired to determine the relative and/or absolute axial position of
an end of a conduit, such as tubing or pipe, whether the conduit
end is positioned with a fluid coupling, a fluid flow device or so
on.
[0022] Determining the nature or quality of contact is also
particularly useful, for example, with the aforementioned tube
fittings. In particular, the fitting body includes a generally
radial shoulder against which the tube end is preferably abutted
after a complete pull-up of the fitting. By "pull-up" is simply
meant the final assembly and tightening of the coupling nut (beyond
the initial finger tight assembly) and body so as to secure the one
or more ferrules onto the tube end in a seal-tight manner. The
quality of this abutting relationship is affected by many factors,
including but not limited to, the facing operation of the tube end,
such as the degree of flatness and square alignment of the tube
end, the nature of the radial shoulder in the body including its
flatness and square alignment, the amount of tube deformation that
may occur during pull-up, the amount of compressive load between
the tube end and the body shoulder, and so on. The quality of the
bottoming is therefore a general reference to the completeness of
the bottoming and the load between the abutting surfaces, as
exhibited by the nature of the contact in terms of the amount of
contact area, the characteristics of the abutting surfaces and so
on. The particular characteristics of quality and nature of the
abutment may be selected as required for a particular application.
Again, the invention will find application beyond two ferrule
flareless tube fittings, and may be used in many applications
wherein it is desired to determine the quality of the abutment
between a conduit end and a surface in a fluid element such as a
tube fitting, a flow control device and so on. In many coupling
applications, simply knowing the quality of the conduit end
insertion, for example whether the conduit end is fully bottomed,
partially bottomed or not bottomed, is the most useful information,
regardless of the ability to detect axial position of the conduit
end.
[0023] In the exemplary embodiments herein, the invention is
realized using ultrasonic energy as an input energy signal. The
more specific, but not necessarily required, characteristics of the
ultrasonic energy in the exemplary embodiments is ultrasonic energy
in the form of a generally continuous mechanical wave or waves
having one or more discontinuities. In other words, the input
energy may be applied as a series of one or more transient
waveforms. The input energy signal in the exemplary embodiments
therefore is in the form of one or more packets or pulses of the
energy waveform. By "pulse" or "packet" we do not intend to
restrict the waveform of the input signal to any particular or
required waveform shape or characteristic either in the time,
frequency, wavelength or amplitude domains. In the exemplary
embodiments, the input energy signal is realized in the form of a
transient signal having one or more harmonic waveforms with
decreasing amplitudes over the time duration of the transient
signal. The input waveform characteristics may be selected to
facilitate analysis of the return signals, such as by the
correlation techniques described herein. Alternatively, the applied
waveform may be any Fourier series waveform for example, including
an impulse harmonic waveform, a square wave, and so on. Those
skilled in the art will appreciate that the invention may be used
with any conveniently available form of reflectable mechanical
energy, as distinguished from electromagnetic energy such as
x-rays, that is transmitted by pressure waves in a material medium,
such as, for example, the conduit or one or more parts of a fluid
coupling, and detected therefrom.
[0024] While the invention is described and illustrated herein with
particular reference to various specific forms and functions and
steps of the apparatus and methods thereof, it is to be understood
that such illustrations and explanations are intended to be
exemplary in nature and should not be construed in a limiting
sense. For example, the present invention may be utilized with any
fluid coupling between a conduit and a fluid flow member including
but not limited to another conduit. The term fluid coupling
therefore is used in its broadest sense to refer to any mechanical
connection between a conduit end and an abutment surface of another
fluid flow element. Furthermore, while the invention is described
herein with reference to stainless steel tubing and tube fittings,
the invention will find application with many other metals and
indeed non-metal applications such as plastics, as well as to
tubing, pipe and so on.
[0025] Additionally, various aspects of the invention are described
herein and are illustrated as embodied in various combinations in
the exemplary embodiments. These various aspects however may be
realized in alternative embodiments either alone or in various
other combinations thereof. Some of these alternative embodiments
may be described herein but such descriptions are not intended to
be a complete or exhaustive list of available alternative
embodiments or modifications. Those skilled in the art may readily
adopt one or more of the aspects of the invention into additional
embodiments within the scope of the present invention even if such
embodiments are not expressly disclosed herein. Additionally, even
though some features and aspects and combinations thereof may be
described herein as having a preferred form, function, arrangement
or method, such description is not intended to suggest that such
preferred description is required or necessary unless so expressly
stated. Those skilled in the art will readily appreciate that the
invention may be used with additional modifications, improvements
and equivalents either known or later developed as substitute or
alternatives for the embodiments described herein.
2. Detailed Description of Embodiments of the Invention
[0026] With reference to FIG. 1, there is illustrated a highly
successful two ferrule tube fitting A. This fitting A is described
in U.S. Pat. No. 3,103,373 owned by the assignee of the present
invention and fully incorporated herein by reference. The
illustration of FIG. 1 shows only one half of the fitting, it being
recognized by those skilled in the art that the other half of the
view is identical about the centerline CL.
[0027] The fitting A includes a body B, a nut C that is threadably
engaged with the body B during finger-tight assembly and pull-up, a
front ferrule D and a back ferrule E. The fitting A is illustrated
installed on a conduit, in this case in the form of a tube end T.
The tubing T may carry a media such as liquid, gas, slurry and so
on. The assembly in FIG. 1 is illustrated in the pulled-up
condition, with the ferrules D and E plastically deformed so as to
provide a fluid tight seal and strong grip on the tube end T.
[0028] It is desirable that the inner end F of the tube end T abut
at the region TA defined at a radial shoulder G formed in the body
B. This abutment is referred to as "bottoming" the tube end T and
is desirable to provide a strong mechanical assemblage, including
forming a good seal and having a strong tube grip, that can
withstand environmental conditions such as temperature variations
and vibration effects. A seal may but need not be formed at the
abutment between the surfaces F and G. Whether a seal is formed
there or not, it would be advantageous to be able to determine that
the tube end is bottomed and the quality, nature or completeness of
the contact. A tube end could be partially or incompletely bottomed
by virtue of the assembler failing to properly insert the tube end
sufficiently into the body B in accordance with the manufacturer's
instructions.
[0029] A fully bottomed conduit end would be a condition in which
there was substantial surface to surface contact between the
conduit end and the body shoulder and good solid mechanical contact
or compression therebetween. A partially bottomed conduit end would
be a condition in which, for example, there is not substantial
surface to surface contact due to poor end facing of the conduit
end, a cocked or tilted conduit, or simply a lack of strong
compression between the two abutting surfaces. A conduit end that
is not bottomed would be a condition of little or no surface to
surface contact or the presence of an actual axial gap between the
non-abutting surfaces. Therefore, as used herein, the nature or
quality of the contact between the conduit end and the abutting
surface refers generally but not exclusively to various features
either alone or in various combinations including the amount of
surface area where contact is made, the force or load between the
conduit end and the abutting surface, presence of a gap
therebetween, lack of square alignment of the abutting surfaces,
and so on.
[0030] With reference to FIG. 2 we illustrate a first embodiment of
the invention. An input energy source or input device 12 is coupled
to the conduit T so as to apply mechanical input energy into the
conduit T, wherein a portion of the applied input energy is
reflected back or returned. The source device 12 may be, for
example, a transducer that converts an electrical drive signal into
vibration or mechanical energy. One example is an ultrasonic
transducer that emits a high frequency signal which may be
reflected or otherwise returned to the source 12 by a variety of
conditions including but not limited to inclusions,
micro-structural deformations, voids, the tube end F, and tubing
deformations or indentations such as the ferrule bite or
compression. The source 12 is used as a transmitter as well as a
receiver or sensor and converts the reflected energy that reaches
the source 12 into a corresponding electrical signal.
Alternatively, the transmitter and receiver may be separate or
different devices. The source 12 is coupled via a cable 14 or other
suitable connection to an electronics arrangement 16. The
electronics 16 includes appropriate circuitry that generates the
drive signal for the source device 12 and that receives the
electrical signals from the source device 12.
[0031] We have found that--although a surface wave transducer or a
delay line transducer may be used to determine the bottomed
condition of a tube end, as well as proper assembly of the tube
fitting, and that either of these transducers is a useful
alternative to the exemplary embodiment herein--a preferred
technique and device is to use a shear wave transducer to apply the
input energy to the conduit T. A shear wave transducer is
distinguished from a delay line transducer in that the shear wave
transducer applies energy into an object generally longitudinally
or along the direction of the surface of the object, whereas a
delay line transducer applies energy generally normal to the
surface, and thus may be used to determine wall thickness. The
shear wave transducer is thus able to produce a better return
reflection or echo of the end of the conduit, particularly when the
conduit is only partially bottomed or completely not bottomed.
[0032] A suitable and exemplary transducer is a Phoenix-ISL shear
wave transducer model SSW-4-70 that is resonant at 4 Megahertz.
Other transducers commercially available or later developed will
also be suitable for the present invention, and the invention is
not limited to the use of ultrasonic energy waves. Non-ultrasonic
wave frequencies may be used provided that adequate and detectable
energy is reflected back from the tube end. It is also possible to
use a tuned frequency that provides the strongest echo from the
conduit end depending on the conduit dimensions, material,
temperature, the fluid coupling associated therewith, and so
on.
[0033] It is worth noting at this time that a particular advantage
of the present invention is that it may be used to determine the
bottoming condition of a conduit within a fluid coupling in a
non-destructive manner, even while the fluid is present in the
conduit. Thus there is no need to necessarily purge the system or
disassemble any components, although such may be desirable in some
circumstances.
[0034] We have further found that easily interpreted data can be
obtained after noise filtering and performing correlation analysis
to the reflected energy. We have moreover found that a Morlet
wavelet function, well known to those skilled in the art as to its
mathematical form, aids the filtering function with the invention,
however, the present invention is not limited to using such a
Morlet wavelet function. For example, other types of exponential
sinusoidal wavelet functions, or other filtering functions, may be
alternatively useful in some applications.
[0035] With reference to FIG. 3, we illustrate a detailed
functional block diagram of the electronics arrangement 16 in the
form of an analyzer. It is desirable that the invention be realized
in the digital analysis domain, however, such is not required and
it may be suitable in some applications to perform analog or hybrid
analog/digital analysis.
[0036] FIG. 3 also illustrates additional aspects of the invention
relating to the mounting of the source 12. In this example, the
source 12 is a shear wave transducer and is firmly supported on a
base 20 that can be suitably attached to or placed in contact with
the conduit surface TS. The base 20 preferably is made of a high
transmission material, such as acrylic resin, so that the energy
emitted from the transducer face 22 is coupled with good efficiency
into the conduit T. The use of a base 20 or other suitable
structure enhances the coupling because the base 20 can be provided
with a surface 24 that conforms to the surface profile of the
conduit surface TS. This usually will be an improvement over simply
trying to position the typically flat transducer face 22 against a
cylindrical surface TS, however, in some applications, especially
large diameter conduits, such a direct mounting may be useable. A
suitable low attenuation coupling material may also be applied
between the base surface 24 and the conduit surface TS. A suitable
low attenuation liquid couplant may be water for example, however
other coupling material such as solid or paste may be used, such as
for example, latex or silicone rubber or AQUALENE.TM. available
from R/D Tech. The use of a coupling material may be omitted in
cases where the signal coupling between the conduit and the
transducer does not adversely attenuate either the drive signal
into the conduit or the reflected energy back into the
transducer.
[0037] FIG. 3 illustrates that the base 20 may be configured so
that the transducer face 22 is angled away from normal towards the
conduit longitudinal axis CL. In this manner, the input energy
enters the conduit structure at an angle .theta..sub.R. We have
found that a suitable range for .theta..sub.R is from about greater
than 0.degree. to about 90.degree., more preferably about
45.degree. to about 85.degree., and most preferably about
65.degree. to about 75.degree.. However, the selected angle for
.theta..sub.R in any particular application may be selected based
on the angle that produces the best or most useful return energy
profiles. Materials having appropriate indices of refraction may be
selected to allow refraction to assist in the input energy entering
the coupling assembly at the desired angle .theta..sub.R.
[0038] With continued reference to FIG. 3, the analyzer 16 may be
realized in the form of any suitable digital processor including
but not limited to DSP, microprocessors, discrete digital circuits
and so on. The analyzer processor 16 may conveniently be any
commercially available or later developed circuit that is
programmable in accordance with programming techniques well known
to those skilled in the art, to carryout the functions described
herein. The analyzer processor 16 thus includes a signal generator
26 that produces a suitable drive signal that is coupled to the
transducer 12 via a suitable cable or wire 28. The analyzer
processor 16 further includes a filter function 30 that may be used
for noise reduction, since the electrical signal from the
transducer 12 will typically include a substantial amount of
background undesired noise. Any suitable filter design in circuitry
or software well known to those skilled in the art may be used.
Note that in FIG. 3 the noise filtering function is performed on
the analog signal from the transducer 12. Alternatively, digital
filtering may be performed in cases when the transducer signal has
been digitized. Still farther, a filter function may be included in
the transducer itself, and special shielding on the cables and
transducer assembly may be used as required to further reduce
noise.
[0039] The filter function 30 receives the electrical output signal
from the transducer 12 via a cable or other suitable connection 32
(note that the wire 32 and the wire 28 are part of the
aforementioned cable 14 of FIG. 2).
[0040] The filtered signal from the transducer 12 is then input to
a conventional analog to digital (A/D) converter 34. The A/D
converter 34 converts the electrical signal from the transducer 12
into a digitized signal that can be conveniently stored in a
storage device such as a memory 36. The memory 36 may be volatile
or non-volatile memory or both depending on the type of data
analysis to be performed.
[0041] In some applications, the reflected energy signal may have a
very pronounced and easily discernible signal level that
corresponds to the axial position of the conduit end relative to
the energy source 12. Note that the axial position of the conduit
end relative to the transducer may be determined either as an
absolute number or a relative number, and is computed based on
knowing the propagation speed of the energy through the conduit, as
is well known in the art of ultrasonic analysis. If the reflected
energy provides an easily discernible signal stored in the memory
36, then the controller 16 can simply be programmed to determine
the characteristics of the signal to ascertain the axial position
of the conduit end.
[0042] In accordance with another aspect of the invention, the
relative strength of the reflected energy is an indication of the
quality of the bottoming. We have found that when there is good or
complete bottoming, very little energy is returned from the conduit
end because the energy passes through into the fitting body
material (and/or other contacting structures) and there is thus a
substantial attenuation in the reflected or returned energy. Thus
interestingly, the absence of a strong reflected energy level
actually indicates excellent bottoming. For an un-bottomed conduit
end, a high and sharply pronounced reflected energy level is
returned due to reflection at the gap interface between the conduit
end and the body shoulder. For a partially bottomed conduit end,
the reflected energy will be somewhere in between a fully bottomed
conduit end and an un-bottomed conduit end. Test samples and
empirical data may be used to calibrate the system 16 as
required.
[0043] We have further found through experimentation, however, that
the mechanical complexity of a typical fluid coupling and conduit
micro-structure renders a nice clean easy-to-detect reflected
energy signal to not be a practical reality. Instead, all sorts of
false or non-repeatable echoes may arise. Furthermore, we have
found that for a single axial location of the transducer relative
to the conduit end, the circumferential position of the transducer
may significantly influence the nature of the reflected energy. For
example, the reflected energy from the conduit end may not always
appear at the same time delay marker when the transducer is moved
about different circumferential positions, even at the same axial
location, on the conduit. We attribute this to micro-variations in
the conduit and the fluid coupling structure, but whatever the
causes may be, the practical consequence is that they typically
will be present.
[0044] In accordance then with another aspect of the invention, the
energy applied into the conduit T is done at two or more
circumferential positions about the selected axial location of the
source transducer 12. This is illustrated in FIG. 4 wherein
reflected energy data is collected and stored for two or more
circumferential positions of the source transducer 12 about the
conduit at the axial location selected. This can be performed using
a plurality of transducers positioned at different positions about
the conduit T, or more simply by repositioning a single transducer
12 and then collecting data at each location as indicated by the
dashed lines in FIG. 4. The different positions may be but need not
be evenly spaced about the conduit.
[0045] Each application of input energy at a particular
circumferential position produces reflected or return energy that
is converted into an electrical signal, filtered and stored as
previously described herein. Data is collected for two or more, and
preferably about three, different circumferential positions at the
selected axial location of the transducer (which in the exemplary
embodiment is just behind the nut C of the fitting assembly A.) A
correlation function 40 is then applied to the set of data from the
plurality of circumferential positions. The correlation analysis
substantially eliminates or "filters" the random return energy
signals from the micro-variations in the conduit because their
positions relative to the applied energy transducer source 12
changes as the transducer is repositioned about the conduit T. The
conduit end relative position, however, does not, and correlation
analysis distinctly discriminates the corresponding signal. The
correlation analysis may be conventional, such as for example but
not limited to, the analysis disclosed in Correlation Analysis of
Spatial Time Series Datasets: A Filter and Refine Approach, Zhang,
Huang, Sheldiar and Kumar, University of Minnesota, Technical
Report Abstracts, 2001, the entire disclosure of which is fully
incorporated herein by reference. We have found that the selected
signal correlation analysis may be significantly facilitated by
optionally but preferably using the wavelet based correlation
method disclosed in Complex Wavelet Analysis of Ultrasonic Signals,
Hull, Yang, and Seymour, to be published in IMechE (Institution of
Mechanical Engineers, London), June, 2003, the entire disclosure of
which is fully incorporated herein by reference, and which may be
implemented/programmed in software or firmware using conventional
and well known techniques. The analyzer 16 can thus produce an
output 42, in any suitable form including but not limited to a
visual output, printed output and so on, of the quality of the
conduit end bottoming and, if so desired or alternatively
separately desired, the absolute or relative axial position of the
conduit end as a function of the axial location of the source
12.
[0046] The present invention contemplates not only the structure of
the aforementioned apparatus, but also the methods embodied in its
use, and furthermore a method for determining position of a conduit
end within a fluid coupling and a method for determining the
quality of the bottoming of a conduit end against a structural
surface. Such a method includes the steps of applying energy into
the conduit structure, detecting reflected or returned energy from
the conduit end and determining the position of the conduit end as
a function of the location of the source. In another method, the
quality of the bottoming of a conduit end is determined by applying
energy into the conduit structure, detecting reflected or returned
energy from the conduit end and determining the quality of
bottoming of the conduit end as a function of the reflected energy
signal strength. Both methods may be used alone or in combination
with each other or other analysis, and both methods may optionally
utilize the above-described noise filtering and correlation
techniques.
[0047] As some of the many available alternatives, the electronics
16 may be incorporated into any suitable package for use in the
desired application and environment. For example, the electronics
16 including the source 12 may be incorporated into a device or
tool that also is used as a conventional gap gauge. The electronics
16 may produce an output of any desired format, and for example,
could simply be a light that indicates a go/no go result of the
bottoming of the tube end. The electronics may also incorporate
intelligent rules based software such as neural nets for
calibration and/or analysis and may include the above described
noise filtering and correlation techniques.
[0048] The source 12 may alternatively be configured to apply the
input energy into a component of the fluid coupling, rather than or
in addition to the conduit. This would only require a simply
reconfiguration of the interface geometry of the base 20 for
example. Depending on the surface for mounting, the base 20 may
even be unnecessary. For example, the source 12 may apply the input
energy into the fitting body B, such as at the head or neck of the
fitting body.
[0049] Still further, the present invention may be used to
determine, separately or in combination with the conduit end
position, other evaluations of the fitting assembly. As described
herein above, the present invention may be used to determine the
position and abutment characteristics of the conduit end. The
invention may also be used to determine the position and
characteristics of other normal deformations and structural
variations of the conduit such as are associated with the fluid
coupling, as such conditions may also produce reflected energy. For
example, but not limited thereto, the invention may be used to
detect the presence and/or location of the bite or tube indentation
or compression caused by one or more of the ferrules. By
determining that the selected condition is positioned properly and
has the desired quality, the user may know that the fitting
assembly has been properly completed, such as knowing that the
ferrules are correctly installed and pulled up. Absence of such
signals may indicate improper assembly or pull-up.
[0050] In another embodiment, the invention is a tool that can be
used to check both the correctness of the geometric pull-up and the
internal integrity of a twin-ferrule tube fitting. Using ultrasonic
sensor(s) and a microprocessor embedded with advanced mathematical
software, the tool will be able to detect if the tubing is fully
bottomed against the tube bore shoulder (i.e. correct tube
installation, See Feature 4). The main advantage of this design is
to provide an alternative that is non-destructive (e.g. actual
disassembly/re-assembly of fitting) and low in cost (relative to
X-raying fitting connections) and greatly reduces the potential for
the product to be installed improperly.
[0051] The hand-held tool shown in FIGS. 5-7 verifies correct
geometric pull-up, as shown in Feature 8 (i.e. 11/4 turns past
finger-tight by gauging the "nut-to-body" gap) and detects if the
tubing is fully bottomed against the tube bore shoulder. Further,
use of the tool does not require the fitting to be disassembled and
thereby eliminates the need to use of X-ray equipment. The
tube-gripping portion of the tool verifies the correctness of the
geometric pull-up by gauging the "nut-to-body" gap. The nut-to-body
gap is held consistent due to tightly toleranced critical
dimensions placed on the nut, ferrules, and fitting body. This
feature is designed such that the tool cannot fit in between the
nut and the fitting body when the required "nut-to-body" gap is
reached. As such, the tool acts as a conventional gap gauge, as
disclosed in U.S. Pat. No. 3,287,813, the disclosure of which is
fully incorporated herein by reference. The back end of the tool
detects if the tubing is fully bottomed against the tube bore
shoulder, located inside the fitting body (i.e. correct tube
installation). Using one or more ultrasonic sensors and a
microprocessor embedded with advanced mathematical software, the
tool can selectively scan critical internal features of the fitting
body and components and notify the user, audibly or visually, if
the tubing is correctly installed. The tool may scan the fitting
using any of the methods described herein above.
[0052] The invention has been described with reference to the
preferred embodiment. Modifications and alterations will occur to
others upon a reading and understanding of this specification. It
is intended to include all such modifications and alterations
insofar as they come within the scope of the appended claims or the
equivalents thereof.
* * * * *