Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CERTIFICATION OF A WELD PRODUCED BY FRICTION STIR WELDING
Field of the Invention
[0001] The field of the invention is friction stir welding (FSW).
Background
[0002] The background description includes information that may be useful in
understanding
the present inventive subject matter. It is not an admission that any of the
information
provided herein is prior art or relevant to the presently claimed inventive
subject matter, or
that any publication specifically or implicitly referenced is prior art.
[0003] Friction stir welding ("FSW") is a solid-state welding process in which
a rotating tool
heats and intermixes two workpieces at a seam (e.g., a junction, joint, or
boundary between
the workpieces). More specifically, the rotating tool has a pin that is
pressed into the seam as
the tool rotates, producing frictional heat between the tool and the
workpieces. Enough heat
is generated such that regions of the workpieces plasticize. A shoulder of the
FSW tool
assists in causing the plasticized regions to intermix, thus joining (i.e.,
FSW) the workpieces
at the seam. The rotating tool travels along the entire length of the seam to
form a weld joint
line between the two workpieces.
[0004] FSW provides numerous advantages over other welding processes, in part,
due to the
fact that FSW occurs at much lower temperatures and without a filler material.
Some of the
advantages of FSW include: better mechanical properties at the weld; less
porosity,
shrinkage, and distortion; little or no toxic fume emissions; no consumable
filler material; and
ease of automation. Since its conception in 1991, FSW has been heavily
researched and
successfully applied to numerous industries in a wide variety of applications.
[0005] The ability to produce high quality and high strength welds has made
FSW an
attractive process for joining large-diameter pipe sections made of high
strength, such as
those used in transporting petroleum. However, in order to achieve a high
quality weld,
many different process parameters must be monitored and controlled (e.g.,
travel speed rate,
rotational speed rate, alignment, pressure, temperature, etc).
[0006] Numerous references describe FSW systems that have sensors for
monitoring and
controlling FSW process parameters in order to achieve high quality welds.
U.S. Patent No.
5,893,507 and International Patent Application Publication No. WO 00/02704,
for example,
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describe FSW systems that monitor and/or control pressure at the FSW tool tip
using pressure
sensors. U.S. Patent No, 6,050,475 describes a method of maintaining a
constant pressure at
the FSW tool tip by using the current of a drive motor to estimate actual
pressure. U.S.
Patent No. 6,299,050 describes a FSW system that monitors and controls the
distance
between the FSW tool and the workpieces using a sensor just ahead of the
moving FSW tool.
International Patent Application Publication No. WO 98/13167 describes a FSW
system that
uses an ultrasonic device to measure variations in the thickness of the
workpieces in order to
control the distance between the FSW tool and the workpieces.
[0007] Other examples of FSW processes that monitor and control process
parameters using
sensors are found in European Patent Application EP2094428, U.S. Patent
Application No.
2012/0261457, and International Patent Application Publication No. WO
2012/133411.
[0008] These and all other extrinsic materials discussed herein are
incorporated by reference
in their entirety. Where a definition or use of a term in an incorporated
reference is
inconsistent or contrary to the definition of that term provided herein, the
definition of that
term provided herein applies and the definition of that term in the reference
does not apply.
[0009] Even when FSW process parameters are carefully monitored and
controlled, a certain
number of defects will inescapably be present in a weld. Examples of common
defects
include volumetric defects (e.g., gaps or voids), root flaws or weld line
defects (e.g., a portion
of the seam fails to bond along the weld line), joint line remnants (i.e.,
when remnants of
undesirable joint line materials, such as surface oxidation, mix into the
weld), and excessive
flash (i.e., when workpieces are overly heated and the FSW tool ejects
material from the weld
region). Weld deflects reduce weld quality and can even cause the weld to fail
(e.g., break,
crack, leak).
[0010] There are a variety of destructive and nondestructive methods for
detecting such
defects, including both "offline" (e.g., after the welding is completed) and
"online" (e.g.,
while the weld is still in process or the workpieces are still associated with
the FSW device)
methods. Online, nondestructive methods are often preferable, as they have the
potential to
allow repair of the defect while the workpieces are still in place and the
equipment is in
operation. Online methods are especially preferred when the FSW equipment is
large, heavy,
and difficult to transport.
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[0011] Visual inspection is one example of an online nondestructive method for
detecting
defects. Visual inspect can be an effective, although labor intensive, method
of identifying
surface flaws. Visual inspection can be automated through the use CCD cameras
and
appropriate image processing hardware and software.
[0012] Radiographic testing is another example of an online nondestructive
method for
detecting defects in welds and can even be used to identify "hidden" defects
(i.e., defects not
readily observable with the natural eye). Radiographic testing operates by
exposing the weld
to a radiation source (e.g., emission from gamma radiation sources such as
192Ir, 60Co, and
137Cs) and measuring the amount of radiation that penetrates the workpiece.
Radiographic
testing provides information on the thickness and composition of the weld.
[0013] Another method for online nondestructive testing is ultrasonic
characterization. This
method provides information on the density distribution of materials and is
well suited for
detecting voids and root flaws. U.S. Patent Application Publication No.
2003/0057258, for
example, discloses a FSW machine that includes an ultrasonic probe that trails
the path of the
FSW tool to identify and mark defects. U.S. Patent Application Publication No.
2009/0140026A1 and Japanese Patent Application Publication No. JP2004317475
also
disclose the use of ultrasonic probes to characterize defects in FSW welds.
[0014] Yet another example of an online nondestructive testing method is eddy
current
detection, which yields information regarding the density and composition of
material within
the weld. Unfortunately, eddy current detection does not penetrate workpieces
well and thus
is limited to relatively thin workpieces. Examples of FSW systems that include
eddy current
detection of defects are found in U.S. Patent Application Nos. 2010/0117636A1,
2004/239317, and U.S. Patent No. 6,168,066.
[0015] Other methods of detecting defects in welds involve inferring the
presence of a defect
based on correlative data. For example, "Monitoring and Control in Friction
Stir Welding"
by Paul A. Fleming (dissertation submitted to the Faculty of Graduate School
of Vanderbilt
University, May, 2009) describes utilizing acoustic and electromagnetic
emissions generated
by the FSW tool during the welding process to infer the presence of defects in
a weld.
Similarly, attempts have been made to train neural networks to associate force
and torque
data gathered during FSW with the presence of weld defects. While these
attempts have
shown some success, those of ordinary skill in the art have failed to produce
adequate
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quantitative information about the presence and severity of specific defects
to provide an
online certification method.
[0016] As used herein, "online certification" as it applies to FSW, means to
provide a
certification of a FSW weldment while the FSW device is still associated with
the workpieces
that are being joined. As used herein, "associated" means that the FSW device
is still
attached to, in physical contact with, or at least within close proximity to
(e.g., in the same
room, building, or worksite), the workpieces. The terms "dissociation,"
dissociated,"
"disassociate" and the like are used herein to refer to a FSW device that is
no longer
associated with the workpieces and/or weld site (e.g., the FSW device has been
detached
from and/or removed from the worksite).
[0017] While various methods of detecting weld defects and flaws are known,
these methods
fail to provide an online nondestructive method for automatically or semi-
automatically
certifying that a weld complies with the standards of standard setting
organization. Examples
of standard setting organizations include the International Organization for
Standardization
(ISO), the American Welding Society (AWS), and the American Society of
Mechanical
Engineers (ASME). Since the certification of weld quality is critical in
certain applications, it
would be advantageous to determine whether a weld passes certification while
workpieces
and FSW devices are still associated with one another, thereby facilitating
efficient repair of
the flawed piece.
[0018] Thus, there remains a need for a system and method that provides online
certification
of friction stir welds.
Summary of The Invention
[0019] The inventive subject matter provides apparatus, systems, and methods
of acquiring
certification-related information related to a weld. In one aspect of some
embodiments, the
method comprises utilizing a FSW device to produce a weld that joins two or
more
workpieces, and operating a sensor to gather data related to one or more
properties of the
weld. In some embodiments, the step of operating a sensor to gather data is
performed while
the FSW device is still attached to, or in physical contact with, the
workpieces. In other
embodiments, the step of operating a sensor to gather data is performed after
the FSW device
has been removed from the workpieces, but still within close proximity to the
workpieces
(e.g., in the same room, building, or worksite).
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[0020] Contemplated methods may also include the steps of storing the sensor
data in an
electronic storage medium and comparing the data to a set of certification
data. The
certification data represent a set of threshold weld characteristics that are
defined by an
extrinsic standard setting organization (e.g., ISO, AWS, ASME, etc). In some
embodiments,
the threshold characteristics correspond to a FSW standard. For example, the
threshold
characteristics may correspond to ISO code no. 25239-5:2011. Alternatively,
the threshold
characteristic may correspond to an AWS D17.3/D17.3M:2010. In some
embodiments, the
threshold characteristics may correspond to two or more sets of FSW standards.
[0021] The step of comparing the sensor data to the certification data is
preferably performed
automatically and electronically using a certification engine and while the
FSW device is still
associated with the workpieces.
[0022] In yet other aspects, contemplated methods include the step of
reporting a certification
status of the weld to a user. For example, a report may be generated for the
user that
compares a sensed characteristic of the weld to the corresponding threshold
characteristic. In
some embodiments, the certification status is reported prior to separation of
the workpieces
from the FSW device. In other embodiments, the certification status is
reported while the
FSW device is still within about 10 meters of the weld.
[0023] Examples of sensor data include, but are not limited to, data related
to a conductivity,
density, permittivity, magnetic permeability, radiolucency, and/or optical
characteristics (e.g.,
reflectivity, color) of the weld. Other examples of sensor data include
temperature data of the
weldment and workpieces, temperature data of the FSW tool, and load data
(e.g., force data)
of the FSW tool in the x, y, and z directions.
[0024] In other aspects of some embodiments, sensor data can be gathered from
either one
sensor, or a plurality of sensors. Alternatively, a single sensor that
utilizes multiple sensory
modes may be used.
[0025] The inventive subject matter also provides a FSW device that includes a
first arm that
is coupled with a FSW tool and a second arm that is coupled with a sensor that
produces a
signal which includes sensor data. The FSW device further includes a control
system that
controls movement of the first arm and second arm and a certification engine
that receives the
sensor signal and compares the sensor data to certification data. The FSW
device can also
include a reporting engine and reporting device coupled with the certification
engine and
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configured to report certification status of the weld to a user. In such
embodiments
certification data may represent one or more threshold weld characteristics
defined by an
extrinsic standard setting organization.
[0026] Various objects, features, aspects and advantages of the inventive
subject matter will
become more apparent from the following detailed description of preferred
embodiments,
along with the accompanying drawing figures in which like numerals represent
like
components.
Brief Description of The Drawing
[0027] Fig. 1 shows a schematic of a method of acquiring certification-related
information
related to a weld.
[0028] Fig. 2 shows a friction stir welding tool for joining two pipe
segments.
[0029] Fig. 3 shows a friction stir welding device that has sensors and a
certification engine.
[0030] Fig. 4 shows a schematic of a certification engine for acquiring
certification-related
information and reporting a certification status.
Detailed Description
[0031] The following discussion provides many example embodiments of the
inventive
subject matter. Although each embodiment represents a single combination of
inventive
elements, the inventive subject matter is considered to include all possible
combinations of
the disclosed elements. Thus if one embodiment comprises elements A, B, and C,
and a
second embodiment comprises elements B and D, then the inventive subject
matter is also
considered to include other remaining combinations of A, B, C, or D, even if
not explicitly
disclosed.
[0032] It should be noted that while the following description is drawn to
certification
systems for FSW devices and processes, various alternative configurations are
also deemed
suitable and may employ various computing devices including servers,
interfaces, systems,
databases, agents, peers, engines, controllers, or other types of computing
devices operating
individually or collectively. Such computing devices may be integrated into a
FSW device,
or may be nonintegrated devices that are located proximate to the FSW device.
Alternatively,
various computing components can be located at a remote site. One should
appreciate that
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computing devices comprise a processor configured to execute software
instructions stored
on a tangible, non-transitory computer readable storage medium (e.g., hard
drive, solid state
drive, RAM, flash, ROM, etc.). The software instructions preferably configure
the
computing device to provide the roles, responsibilities, or other
functionality as discussed
below with respect to the disclosed apparatus. In some embodiments, the
various servers,
systems, databases, or interfaces exchange data using standardized protocols
or algorithms,
possibly based on HTTP, HTTPS, AES, public-private key exchanges, web service
APIs,
known financial transaction protocols, or other electronic information
exchanging methods.
Data exchanges preferably are conducted over a packet-switched network, the
Internet, LAN,
WAN, VPN, or other type of packet switched network.
[0033] One should also appreciate that the disclosed techniques provide many
advantageous
technical effects including online nondestructive weld certification methods
and systems.
More specifically, the inventive subject matter provides apparatus, systems,
and methods by
which one can generate an online certification of a friction stir weld. Such
certification
provides the user with documentation that a weld meets acceptance standards
and insures the
quality of the welded workpieces. Alternatively, failure to meet such
standards can serve to
alert a user to flaws in the weld, which may then be repaired while workpieces
are still in
place on the FSW device, thus avoiding costly relocation, remounting, and/or
realignment of
the workpieces with the FSW device.
[0034] Figure 1 illustrates a method 100 of acquiring weld information for
certifying a weld.
Method 100 begins with step 110, in which the workpieces to be welded by a FSW
process
are aligned with a FSW device. In step 110, the FSW process is initiated by
placing a
rotating FSW tool tip at the seam (e.g., joint, junction, boundary, weld site,
etc.) of the
workpieces and applying pressure so that the a pin of the FSW tool tip
penetrates the seam.
Once the proper pressure, depth, revolutions per minute (RPM), and attack
angle of the FSW
tool has been achieved, the FSW tool tip is moved along the path of the
desired weld,
softening and mixing the material of the workpieces to form a weld (also
referred to as a
FSW weldment).
[0035] The workpieces to be welded can be flat pieces, pipe segments, or even
irregular-
shaped pieces. The material of the workpiece can be aluminum, aluminum alloy,
stainless
steel, high strength steel alloys, or any other metal, non-metal, and/or
composite
compositions suitable for use with a FSW process. The inventive subject matter
is not
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intended to be limited to any particular workpiece configuration (e.g., size,
shape,
composition, etc.). Likewise, the inventive subject matter is not limited to
any particular
seam configuration. In some embodiments, the seam is a butt joint or a lap
joint.
[0036] Step 120 involves operating one or more sensors to obtain information
about the weld
for the purposes of characterizing the weld quality (e.g., identifying
defects), providing a
certification status, and/or controlling the FSW process parameters. In some
embodiments,
step 120 is performed while the workpieces are still engaged with the FSW
device (e.g., the
workpieces are still physically attached to, or in contact with, a component
of the FSW
device such as an anvil, platform, or platform clamps). The one or more
sensors may begin
to acquire signals before, during, or even after the FSW process to obtain
information
relevant to characterizing the weld. In some embodiments, the sensor(s) start
to acquire data
before the FSW tool has penetrated the workpieces and continues to acquire
data until the
FSW tool tip is removed from the workpieces and the workpieces have reached
room
temperature.
[0037] Contemplated sensors can include any sensor suitable for gathering data
related to
characterizing a weld and/or controlling process parameters. In some
embodiments, the
sensor comprises an optical sensor configured to detect optical
characteristics of a weld.
Such optical sensors may be used in conjunction with image recognition
software and
hardware that permits characterization of an optical image. Such
characterization may
provide information related to composition, for example, the presence of
oxidized material.
The characterization of optical sensor data may also provide information
related to the
dimensions of a weld, gaps or discontinuities in the weld, and/or the presence
of flash
material.
[0038] In other embodiments, the sensor can comprise a radiation sensor,
configured to work
in concert with a radiation source for radiographic detection. Suitable
radiation sources
include, but are not limited to X ray sources and radioactive isotopes. Such
radiation sensors
provide data related to radiation intensity from such a radiation source when
the weld is
interposed between them. Such data may provide information related to
radiolucency of
material of a weld, gaps or voids within a weld, thickness of a weld, and/or
composition of a
weld.
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[0039] In yet other embodiments, the sensor can comprise an ultrasonic sensor.
The
ultrasonic sensor can include an emitter and a detector, which may be used in
concert to
gather data regarding a weld. Such data includes, but is not limited to,
information related to
the presence of gaps and/or voids within a weld, depth of a weld, density of
the material of a
weld, and discontinuities in a weld.
[0040] Still another embodiment of the inventive method may use an eddy
current sensor
configured to characterize a weld. Such eddy current sensors may utilize a
magnetic field to
induce an electric field in the material of a weld, thereby gathering data
regarding a weld.
Such data includes, but is not limited to, the presence of gaps or voids
within a weld, depth of
a weld, density of material of a weld discontinuities in a weld, composition
of material of a
weld, conductivity of material of a weld, and permittivity of material of a
weld. Such an
eddy current sensor may be an array of eddy current sensors.
[0041] In some embodiments, the sensor can comprise one or more force
transducers (e.g.,
load cells) that measure and record the forces (e.g., load data) experienced
by the FSW tool.
The sensor(s) can be configured to measure forces in all three directions
within a three-
dimensional space: the x-direction (i.e., the direction of travel of the FSW
tool), the y-
direction (i.e., the direction perpendicular to the direction of travel and
within the plane of the
workpiece surface), and the z-direction (i.e., the direction perpendicular to
the plane of the
workpiece surface). For non-planar workpiece surfaces, the "plane" of the
workpiece surface
is a hypothetical plane that is substantially tangential to the workpiece
surface. The three
directions of force are illustrated in Figure 2.
[0042] Figure 2 shows a perspective view of a FSW tool 200, which is about to
engage seam
210. Seam 210 is the junction at which two non-planar workpieces, namely, pipe
segment
220 and 230, meet. During the FSW process, FSW tool 200 will travel in an
orbital fashion
along seam 210 in direction 235 (parallel to the x-direction) to form a weld.
As FSW tool
200 travels, force transducer 250 gathers load data that represent the forces
experienced by
FSW tool 200 in the three directions illustrated by axes 240, namely, the x-
direction, y-
direction, and z-direction. The load data can be used, either independently or
in combination
with other data, to characterize the weld, provide a certification status,
and/or control the
FSW process parameters.
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[0043] Those of skill in the art will appreciate that step 120 of method 100
can comprise
operating a single sensor to acquire information about a weld and could also
comprise
operating two or more sensors to acquire information about a weld. In some
embodiments
step 120 comprises operating a single sensor that utilizes two or more sensing
modes.
[0044] To facilitate the gathering of sensor data prior to disassociation of
the workpieces and
the FSW device, some embodiments may utilize a particular temporal
relationship between
activity of a FSW tool and gathering of data related to a weld characteristic
by a sensor. For
example, a sensor may be configured such that it maintains a fixed distance
from a FSW tool.
In such an embodiment a sensor may gather data characterizing a weld at less
than about 1, 2,
3, 4, 5, 10, 15, 20, 25, 30, 45, or 60 minutes from the production of a weld
or seam.
[0045] In other embodiments, the time at which data is gathered may be related
to the
temperature of the weld, seam, surrounding workpiece, or FSW tool. This
temperature may
correspond to the upper tertile of a functional temperature range of a sensor
mode or
technology. In such an embodiment a sensor may gather data characterizing a
weld after it
reaches a temperature of less than about 25 C, 35 C, 50 C, 75 C, 100 C, 200 C,
350 C, or
500 C.
[0046] In yet other embodiments, the sensor(s) may maintain a particular
spatial arrangement
with a FSW device (or a portion thereof). In such embodiments, the sensor may
follow
behind the FSW tool tip at a fixed distance. Alternatively, a sensor may
follow behind FSW
tool tip at a distance of less than about 1 cm, 2 cm, 5 cm, 10 cm 25 cm, 50
cm, 75 cm, 1
meter, 2 meters, 3 meters, 4 meters, or 5 meters. In addition, the sensor may
be configured to
acquire weld data when the FSW tool tip is less than about 1, 2, 3, 4, 5, 7.5,
or 10 meters
from the weld or seam. In other embodiments the sensor may maintain an angle
relative to
the path of the FSW tool tip. In such embodiments the sensor may trail the
path of the tool
tip at an angle of 0.5 radians, 1 radian, 2 radians, 3 radians, or 4 radians.
[0047] In other aspects of some embodiments, the sensor(s) may be coupled to
an arm of the
FSW device. In some embodiments, an arm holding the FSW tool also holds at
least one
sensor. In other embodiments, the sensors are held by separate arms than the
FSW tool.
[0048] In step 130 of method 100, data obtained from the sensor(s) may be
stored on any
suitable electronic storage medium. Suitable electronic storage media include,
but are not
limited to, magnetic media (such as, for example, a hard drive), SRAM, DRAM,
EEPROM,
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ECC memory, and/or flash memory. The electronic storage medium may be located
proximate to the weld or may be located at a remote site. In some embodiments,
data
obtained from a sensor is transmitted to more than one memory location, for
example to a
computing device integrated into a FSW device and to a remote database or
server utilized by
an offsite plant or project modeling system.
[0049] In step 140, data obtained from the sensor(s) is utilized by a
certification engine. The
certification engine can be configured to perform an operation or algorithm
that relates sensor
data to one or more certification data that represent, or relate to,
certification requirements
and/or standards. One example of certification data may include threshold
values related to
the presence, dimensions, location, and/or number of defects in a weld. In
some
embodiments, the certification data is determined by the user (e.g., the
welder) or entity in
direct or indirect control of the FSW process (e.g., general contractor or
Engineering/Procurement/Construction firm). In a preferred embodiment of the
inventive
subject matter, the certification data are obtained from an extrinsic standard
setting
organization. As used herein, "extrinsic" entities are entities not under the
control of the user
of the inventive method and/or the FSW device. Examples of extrinsic standard
setting
organizations include, but are not limited to, the American Welding Society,
the International
Standards Organization, and the National Aeronautics and Space Administration.
Certification data can be obtained from weld standards such as ISO 25239-
1:2011 through
ISO 25239-5:2011 and AWS D17.3/D17.3M:2010.
[0050] In some embodiments, the certification data could represent two or more
distinct
standards set by different organizations. In such embodiments, the
certification engine
compares the sensor data with the two or more distinct standards to determine
whether each
standard has been satisfied.
[0051] In other aspects, step 140 may additionally include the step of
configuring the
certification engine to process sensor data to produce derived data. The
derived data can then
be compared with certification data, either in addition to, or instead of the
sensor data (e.g.,
raw data), to determine a certification status. For example, when the sensor
data comprises
load data (from a force transducer) and temperature data (from a temperature
sensor), the
certification engine can be configured to correlate the load data and
temperature data to
provide a new set of derived data. The derived data can then be used to
characterize the weld
and determine a certification status.
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[0052] As another example, the step of producing derived data could include
performing a
fast Fourier transform operation on the temperature data and/or x-direction
load data and y-
direction load data in a manner that characterizes the weld. In addition to
performing a
Fourier transform, the certification engine can be configured to compare the
signal phases of
the x-direction load data and y-direction load data to produce derived data.
The derived data
can then be used to provide a characterization of the weld. It is also
contemplated that the
step of producing derived data could include numerous iterations of
correlations and
derivations using algorithms that account for many FSW process parameters and
sensor data
(e.g., load cell voltage, amperage, tool travel speed, tool RPM, optical data,
temperature
profiles, etc.).
[0053] Step 150 comprises reporting a certification status of a weld. In some
embodiments,
the certification status is reported prior to separating the welded workpieces
from the FSW
device. As noted above, this provides the user with the opportunity to repair
a flawed weld
(should a weld fail to pass certification) without the need to remount and
realign the
workpieces and FSW device. A report of certification status may be provided
directly to a
user of the FSW device. Alternatively, a report of certification status may be
transmitted to a
database of a plant or project modeling system. In some embodiments, a report
of
certification may be provided to multiple sites and/or users. Suitable
reporting devices
include, but are not limited to, a monitor or display, and/or a printer.
Alternatively, a
reporting device may transmit an electronic certification status report in the
form of an email,
text message, and/or database entry.
[0054] Method 100 could additionally include the step of configuring a control
engine or
control module to analyze the sensor data and provide a control signal to an
actuator of the
FSW process. For example, the control signal could cause an actuator to change
the travel
speed, RPM, depth, or z-direction force of the FSW tool. The signal could also
cause an
actuator to change the temperature of a heating/cooling element in contact
with the
workpieces.
[0055] The control engine is preferably configured to provide a control signal
that improves
at least one characteristic of the weld. For example, the control engine could
be configured to
analyze many process parameters in a manner that anticipates the formation of
a defect and/or
the formation of a particular molecular structure (e.g., austenite,
martensite, pearlite, large
grain sizes, small grain sizes, etc.). Based on the inferences derived from
the sensor data, a
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control signal can adjust process parameters to avoid defects while still
achieving the desired
molecular structure.
[0056] Figure 3 shows a FSW device 300 and a seam 310. Seam 310 represents the
joint
between two workpieces, namely, pipe segment 320 and pipe segment 330. Device
300
comprises a frame 305 movably coupled with clamp 307 and clamp 309. Clamp 307
is used
to clamp FSW device 300 to pipe segment 320, while clamp 309 is used to clamp
FSW
device 300 to pipe segment 330.
[0057] Frame 305 has an arm 340 that holds a FSW tool 345. Tool 345 includes a
shoulder
portion and a pin portion. During the FSW process, arm 340 hydraulically
extends toward
seam 310 while rotating FSW tool 345 such that the shoulder portion is pressed
against the
surface of seam 310 while the pin portion penetrates into seam 310. Frame 305
then travels
orbitally around seam 310 via tracks on clamps 307 and 309. The frictional
heat produced by
the rotation and travel of FSW tool 345 is sufficient to melt and mix the
workpieces at seam
310, thus producing a solid sate weldment along seam 310.
[0058] Arm 340 also includes a force transducer 347, which measures load data
in the x, y,
and z directions (see Figure 2) experienced by FSW tool 345.
[0059] Frame 305 also has a first sensor 351 and a second sensor 353. Sensor
351 and sensor
353 collect data relevant to characterizing a weld and/or controlling FSW
process parameters.
Sensor 351 and sensor 353 can comprise any sensor suitable for characterizing
a weld.
Examples of sensors include, but are not limited to, optical sensors,
radiation sensors,
ultrasonic sensors, eddy current sensors, or any sensor modality appropriate
for
characterizing the composition and nature of the weld. Sensor 351 and sensor
353 gather
data before, during, and after the active welding step (i.e., the period
during which FSW tool
345 rotates, penetrates, and travels along seam 310).
[0060] Sensor 351 and sensor 353 produce data signals that are transmitted to
computing
system 360. Computing system 360 includes an electronic storage medium,
processor,
executable code, and other electrical and non-electrical components necessary
for storing and
analyzing electronic data. Computing system 360 also includes a certification
engine and a
control engine. The certification engine is configured to store sensor data
provided by the
signals from sensor 351 and sensor 353 in the electronic storage medium. The
certification
engine is also configured to compare sensor data with certification data to
determine a
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certification status of the weld. In some embodiments, the certification
engine is additionally
configured to analyze sensor data and process parameter data to produce a set
of derived data
that is useful for characterizing a weld.
[0061] The control engine is configured to monitor and record the FSW process
parameters.
The control engine is also configured to produce at least one control signal
that is transmitted
to at least one actuator (e.g., hydraulic systems, servo-motors, etc.). The
control signal
adjusts process parameters during the FSW process to improve weld quality and
process
performance (e.g., efficiency, cost, etc.).
[0062] FSW device 300 also has a heating/cooling element 370 that can regulate
the
temperature of seam 310 before, during, and/or after welding.
[0063] Those of ordinary skill in the art will appreciate that numerous
variations and
alternative configurations for FSW device 300 are possible without departing
from the
inventive concepts described herein. For example, FSW device 300 could include
only one
sensor, or three or more sensors. Some sensors may be in contact with the
workpiece surface
while others may be noncontact sensors. In other aspects, some sensors may be
supported by
a common arm rather than distributed on two or more different arms. Some
sensors may
even be statically placed on the workpieces and remain stationary while frame
305 rotates
orbitally around seam 310.
[0064] Sensor signals could be transmitted to computing system 360 via a wired
connection,
such as an Ethernet cable, a USB cable, a serial data cable, and/or a parallel
data cable.
Alternatively, signals may be transmitted wirelessly via, for example,
Bluetooth and or WiFi
transmission protocols.
[0065] In yet other embodiments, computing system 360 may be located apart
from frame
305. For example, computing system 360 could be a desktop computer located at
the
worksite but physically decoupled from frame 305. In such embodiments,
computing system
360 is still communicatively coupled with the sensors and actuators of FSW
device 360,
either via a wired or wireless communication channel.
[0066] Computing system 360 may include a display (e.g., monitor screen) to
provide
certification status reports to a user. Computing system 360 may also include
any number of
input/output devices for user interaction (e.g., keyboard, mouse, touch screen
display,
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microphone and voice recognition, printers, email capabilities, etc.). In some
embodiments,
computing system 360 may be coupled with an information network, such as, for
example,
the intern& and/or a company intranet.
[0067] While computing system 360 is shown as a single component, computing
system 360
could also comprise a plurality of individual computing devices (e.g.,
distributed
storage/processing, virtual storage/processing, etc.). The executable code
that represents the
certification engine and control engine could be stored together in one device
and in one
electronic file, or across multiple devices and files.
[0068] Figure 4 shows a schematic of a certification and control engine 400.
Engine 400 has
a control module 410 and a certification module 420. Engine 400 receives
sensor signals
from a plurality of sensors 401, 402, and 403 via sensor interface 430.
Interface 430 provides
sensor signal data to modules 410 and 420 for analysis. Control module 410
analyzes sensor
signal data to determine whether adjustments should be made to FSW process
460. If
adjustments need to be made, control module 410 transmits a control signal to
FSW actuator
450 via actuator interface 440. Actuator 450 makes an adjustment to FSW
process 460.
Sensors 401, 402, and 403 produce new sensor signals based on the adjustments
to 460. The
new sensor signals are transmitted to sensor interface 430 and the previous
steps are repeated.
[0069] Sensor signals are also transmitted to certification module 420. Module
420
compares the sensor signals to certification data to determine whether FSW
process 460 has
produced a weld that passes certification standards. In some embodiments the
certification
data is provided by an extrinsic standard setting organization. Certification
module 420
provides a certification status report to user display 480 via user interface
470. In some
embodiments the certification status report is transmitted to user display 480
while the FSW
device of FSW process 460 is still associated with the workpieces.
[0070] Engine 400 is in communication with a database (not shown). Engine 400
stores
sensor signal data on the database as sensor data objects. Engine 400 also
stores other data
objects on the database that represent certification status reports, data
derived from sensor
data, and process parameter data. The database also includes certification
data objects that
represent certification standards. Engine 400 compares sensor data objects
with certification
data objects to provide a certification status report.
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[0071] Different applications of certification and control engine 400 are
illustrated below by
way of non-limiting examples.
Example 1
[0072] Two flat workpieces can be mounted in a FSW device and aligned to form
a butt
joint. The FSW device can be programmed to form a 15 meter long weld at the
joint between
the work surfaces. The FSW tool can be moved along the seam and trailed by a
CCD-based
optical sensor by a distance of 15 cm. Image characterization software can be
utilized to
identify areas of reduced reflectivity and calculate their dimensions and
orientation. This
data can be transmitted to a certification engine, which includes a database
containing ISO
certification standards for FSW welds. The standard could include the
requirement that no
more than 3 weld line defects occur along the length of the weld and that they
occupy no
more than 0.2% of the total length of the weld. The certification engine
interprets sensor data
by applying algorithms that correlate sensor data with weld defects in order
to derive weld
defect data. The certification engine then compares the sensor data and/or
weld defect data
derived from sensor data to the ISO standards.
[0073] A report can be generated by the certification engine indicating that
the weld is either
passes or fails the certification standards. The report may also indicate the
positions and
dimensions of the weld line defects while the welded workpieces are still
engaged with the
FSW device. This allows the operator of the FSW device to repeat portions of
the welding
operation in order to repair these defects without re-mounting.
Example 2
[0074] A FSW device can be used to join two segments of steel pipe with an
internal
diameter of 2 meters. The pipe segments may be aligned and a FSW device
programmed to
move along the external diameter of the joint in order to form a weld at the
joint between the
work surfaces. As the FSW tool moves along the seam it may be trailed by an
ultrasonic
sensor by a distance of 1 meter. The ultrasonic sensor can include an emitter
and a receiver.
Echoes from the emitted ultrasound can be used to characterize the dimensions
of the weld
and enumerate/estimate the dimensions of volumetric defects within the weld by
methods
known in the art. This data can be transmitted to a certification engine,
which includes a
database containing AWS standards for friction stir welds. These standards can
include a
requirement that the accumulated volume of volumetric defects does not exceed
0.05% of the
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total volume of the welded. A report can be generated by the certification
engine indicating
if the weld is certified. The certification engine can be configured to (i)
print the report for
the FSW operator and (ii) transmit the report to a project database associated
with a project
model system.
Example 3
[0075] A FSW device can be used to join planar workpieces. During the FSW
process, a
sensor gathers load data that represents the forces experienced by the FSW
tool in the x, y,
and z directions. The FSW device also includes a plurality of temperature
sensor that
measure the temperature of the workpieces just head of the FSW tool, behind
the FSW tool,
and the area surrounding the seam. The load data and temperature data are
transmitted to a
certification and control engine. The engine monitors and processes the sensor
data and other
process parameters (e.g., FSW tool's rpm and travel speed) and runs an
algorithm(s) that is
configured to anticipate the formation (or probability of formation) of a weld
defect and/or
determine the presence of a weld defect.
[0076] The algorithm(s) utilizes a known correlative relationship between a
temperature
profile (e.g., temperature of an area over time, rates of temperature changes,
etc.) and weld
characteristics (e.g., presence of defects, molecular phase of an alloy, etc.)
to anticipate a
weld defect formation or to determine the presence of a weld defect. The
algorithm(s) also
utilizes a known correlative relationship between load data and weld
characteristics. For
example, the algorithm(s) could apply a fast Fourier transform to the x and y
forces.
Alternatively, the algorithm(s) could compare the phases of the x and y
forces, thus avoiding
the heavy processing requirements of Fourier transform operations.
[0077] When the certification and control engine anticipates the formation of
a weld defect,
the engine sends a signal to various actuators that control and adjust process
parameters (e.g.,
z force, depth of FSW tool, travel speed of FSW tool, RPM's of FSW tool,
etc.). The
certification and control engine also provides real-time certification
reporting that notifies a
user when the weld fails a certification standard. The user can then decide
whether to
terminate the FSW process early or allow the FSW device to continue running.
[0078] As used herein, and unless the context dictates otherwise, the term
"coupled to" is
intended to include both direct coupling (in which two elements that are
coupled to each
other contact each other) and indirect coupling (in which at least one
additional element is
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located between the two elements). Therefore, the terms "coupled to" and
"coupled with" are
used synonymously.
[0079] Unless the context dictates the contrary, all ranges set forth herein
should be
interpreted as being inclusive of their endpoints, and open-ended ranges
should be interpreted
to include commercially practical values. Similarly, all lists of values
should be considered as
inclusive of intermediate values unless the context indicates the contrary.
[0080] It should be apparent to those skilled in the art that many more
modifications besides
those already described are possible without departing from the inventive
concepts herein.
The inventive subject matter, therefore, is not to be restricted except in the
scope of the
appended claims. Moreover, in interpreting both the specification and the
claims, all terms
should be interpreted in the broadest possible manner consistent with the
context. In
particular, the terms "comprises" and "comprising" should be interpreted as
referring to
elements, components, or steps in a non-exclusive manner, indicating that the
referenced
elements, components, or steps may be present, or utilized, or combined with
other elements,
components, or steps that are not expressly referenced. Where the
specification claims refers
to at least one of something selected from the group consisting of A, B, C
.... and N, the text
should be interpreted as requiring only one element from the group, not A plus
N, or B plus
N, etc.
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