U.S. patent application number 13/962993 was filed with the patent office on 2014-02-06 for welding purge control using electronic flow control.
This patent application is currently assigned to Swagelok Company. The applicant listed for this patent is Swagelok Company. Invention is credited to Richard A. Ales, Michael Mussig, William Ponikvar, Kevin Silk, David N. Stafford.
Application Number | 20140034619 13/962993 |
Document ID | / |
Family ID | 39232776 |
Filed Date | 2014-02-06 |
United States Patent
Application |
20140034619 |
Kind Code |
A1 |
Silk; Kevin ; et
al. |
February 6, 2014 |
WELDING PURGE CONTROL USING ELECTRONIC FLOW CONTROL
Abstract
A purging arrangement for a welding system uses automatic flow
control function, such as an MFC, to control purge gas flow rate
and/or pressure at the weld site.
Inventors: |
Silk; Kevin; (Stow, OH)
; Ales; Richard A.; (Solon, OH) ; Ponikvar;
William; (Sagamore Hills, OH) ; Mussig; Michael;
(Painesville, OH) ; Stafford; David N.; (Aurora,
OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Swagelok Company |
Solon |
OH |
US |
|
|
Assignee: |
Swagelok Company
Solon
OH
|
Family ID: |
39232776 |
Appl. No.: |
13/962993 |
Filed: |
August 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12445586 |
Apr 15, 2009 |
8530777 |
|
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PCT/US07/81903 |
Oct 19, 2007 |
|
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13962993 |
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60862233 |
Oct 20, 2006 |
|
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Current U.S.
Class: |
219/121.55 ;
219/60A |
Current CPC
Class: |
B23K 9/325 20130101;
B23K 9/164 20130101; G05D 7/0652 20130101 |
Class at
Publication: |
219/121.55 ;
219/60.A |
International
Class: |
B23K 9/16 20060101
B23K009/16; B23K 9/32 20060101 B23K009/32 |
Claims
1-13. (canceled)
14. Welding system, comprising: a welder power supply, said welder
power supply being connectable to an orbital weld head for
providing electrical power during a welding operation., at least
one mass flow controller, a control system operably coupled to said
at least one mass flow controller, said control system being
configured to control flow rate of a purge gas from said mass flow
controller, a housing that encloses said power supply, said at
least one mass flow controller and said control system.
15. The welding system of claim 14 wherein said housing comprises a
handle that can be manually grasped for portability of the welding
system.
16. The welding system of claim 14 wherein said control system is
operably coupled to said welder power supply and inhibits a welding
operation until a purging operation starts.
17-20. (canceled)
21. A method for controlling purging during a welding operation,
comprising: performing a butt welding operation on end to end
abutting tubular workpieces using an orbital welder, applying a
flow rate profile for purge gas to either an outer diameter region
or an inner diameter region at the weld site, said flow rate
profile comprising at least a first flow rate before a welding
operation begins and a second flow rate during the welding
operation with said second flow rate being lower than said first
flow rate.
22. The method of claim 21 wherein said step of applying a flow
rate profile for purge gas to either an outer diameter region or an
inner diameter region at the weld site comprises a third flow rate
after the welding operation ends with said third flow rate being
higher than said second flow rate.
23. The method of claim 21 wherein said step of applying a flow
rate profile includes using an electronic automatic purge
control.
24. The method of claim 21 wherein a welding operation is
automatically inhibited until purge gas is flowing to the weld
site.
25. The method of claim 21 wherein said step of applying a flow
rate profile includes using a mass flow controller.
26. A method for controlling purging during a welding operation,
comprising: performing a butt welding operation on end to end
abutting tubular workpieces using an orbital welder, applying a
flow rate profile for purge gas to either an outer diameter region
or an inner diameter region at the weld site, said flow rate
profile comprising at least a first flow rate during a welding
operation begins and a second flow rate after the welding operation
ends with said second flow rate being higher than said first flow
rate.
27. The method of claim 26 wherein said step of applying a flow
rate profile for purge gas to either an outer diameter region or an
inner diameter region at the weld site comprises a third flow rate
before the welding operation begins with said third flow rate being
higher than said first flow rate.
28. The method of claim 26 wherein said step of applying a flow
rate profile includes using an electronic automatic purge
control.
29. The method of claim 26 comprising the step of electronically
confirming that purging is functioning properly prior to enabling a
welding operation.
30. The method of claim 26 wherein said step of applying a flow
rate profile includes using a mass flow controller.
31. Welding system for tubular workpieces, comprising: a welder
power supply, the welder power supply being connectable to an
orbital weld head for providing electrical power during a welding
operation; at least one automatic flow control for purge gas, said
automatic flow control having an inlet connectable to a source of
purge gas and an outlet for providing a flow of purge gas to an
outer diameter region of a weld site for tubular workpieces within
the orbital weld head; said automatic flow control applying a flow
rate profile for purge gas to either an outer diameter region or an
inner diameter region at the weld site, said flow rate profile
comprising at least a first flow rate before a welding operation
begins and a second flow rate during the welding operation with
said second flow rate being lower than said first flow rate.
32. The welding system of claim 31 wherein said flow rate profile
comprises a third flow rate after the welding operation ends with
said third flow rate being higher than said second flow rate.
Description
RELATED APPLICATIONS
[0001] The present application is a continuation application of
U.S. Ser. No. 12/445,586, filed Apr. 15, 2009 titled WELDING PURGE
CONTROL USING ELECTRONIC FLOW CONTROL, which is the U.S. national
phase entry of PCT/US2007/081903, filed Oct. 19, 2007, titled
WELDING PURGE CONTROL USING ELECTRONIC FLOW CONTROL, which claims
the benefit of pending U.S. provisional application Ser. No.
60/862,233 filed on Oct. 20, 2006, for WELDING PURGE CONTROL USING
MASS FLOW CONTROL, the entire disclosures of which are fully
incorporated herein by reference.
BACKGROUND
[0002] In arc welding, such as for example an orbital welder, a
welder power supply is used that produces a low voltage high
current power source to maintain a stable arc. The arc is initiated
or struck by a high voltage breakdown across the gap between the
electrode and the workpiece. Once the arc is struck, the voltage
across the gap is much lower than the breakdown voltage and the
current increases substantially. An arc start circuit may be used
to strike the arc, and then the welder power supply is used during
the welding operation.
[0003] One type of welder that is commonly used today is an orbital
welder, in which an electrode revolves around the weld site during
a welding operation. The electrode movement occurs within a weld
head that generally surrounds and generally encloses the weld site.
An orbital welder, for example, is commonly used for butt welding
two tubes or pipes together. During some types of welding such as
for example TIG welding used for stainless steel tubing, it is
important to provide an inert purge gas at the weld site. The purge
gas prevents oxidation and other deleterious effects during the
welding operation The purge gas is provided within the tubing (ID
purge) and around the outside of the tubing (OD purge).
SUMMARY
[0004] In accordance with one inventive aspect of the present
disclosure, a purge system or arrangement is provided that uses an
automatic flow control function, such as for example, a mass flow
controller (MFC), to control the flow and/or pressure of the purge
gas. In one embodiment, an automatic flow control function may be
used for dynamic OD (outer diameter) purge control, in another
embodiment an automatic flow control function may be used for
dynamic ID (inner diameter) purge control, and in still another
embodiment a first automatic flow control function may be used for
dynamic ID purge control and a second automatic flow control
function may be used for dynamic OD purge control.
[0005] In accordance with another inventive aspect of the
disclosure, one or more automatic flow control devices, such as for
example an MFC, may be used for dynamic purge control which may be
incorporated into or integrated with a welder power supply. In one
embodiment, MFC dynamic purge control is incorporated into a welder
power supply for an orbital welding system.
[0006] In accordance with another inventive aspect of the
disclosure, dynamic purge control may be used to carry out a
dynamic purge sequence that includes an increased purge flow rate
during a pre-weld purge operation and optionally an increased purge
flow rate during a post-weld purge operation, or both a pre-weld
and a post-weld high flow purge operations, wherein the pre and
post weld flow rates are higher than the purge flow rate during a
welding operation. In one embodiment, one or more automatic flow
control devices such as MFC devices are used to control flow rate
and/or pressure of the purge gas. The use of MFC type devices, for
example, permits both a dynamic purge sequence as well as an
automatic purge sequence. An automatic flow control function in
another embodiment may be use to confirm that purging begins before
a welding system is enabled for a welding operation.
[0007] In accordance with another inventive aspect of the
disclosure, methods for dynamic purge control are provided,
including dynamic ID purge control, dynamic OD purge control and
optionally both during a welding operation. In one embodiment, an
automatic flow rate control function may be used to compensate ID
purge pressure variation during a welding operation.
[0008] These and other aspects and advantages of the disclosure and
inventions herein will be readily understood and appreciated from a
reading of the following detailed description in view of the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is an exemplary functional block diagram of a welding
system;
[0010] FIG. 2 is an exemplary flow chart of a purge function that
may be implemented, for example, in the system of FIG. 1; and
[0011] FIG. 3 is a simplified schematic of an embodiment of an
orbital welder power supply that includes a purge flow control in a
common housing.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0012] Although the inventive aspects and exemplary embodiments are
described and illustrated herein with reference to an orbital
welder and tubular workpieces, such examples are not to be
construed as limiting the scope of the inventions set forth herein.
Various inventions described herein will find applications beyond
orbital welding or tubular workpieces. Furthermore, although a mass
flow controller (MFC) is illustrated for use with the exemplary
embodiments of an automatic flow control function and automatic
purge control, it is well known that automatic or electronic flow
control may be realized in many ways other than just an MFC, and
the present disclosure is intended to cover all such alternatives,
whether known or later developed.
[0013] While various inventive aspects, concepts and features of
the inventions may be described and illustrated herein as embodied
in combination in the exemplary embodiments, these various aspects,
concepts and features may be used in many alternative embodiments,
either individually or in various combinations and sub-combinations
thereof. Unless expressly excluded herein all such combinations and
sub-combinations are intended to be within the scope of the present
inventions. Still further, while various alternative embodiments as
to the various aspects, concepts and features of the
inventions--such as alternative materials, structures,
configurations, methods, circuits, devices and components,
software, hardware, control logic, alternatives as to form, fit and
function, and so on--may be described herein, such descriptions are
not intended to be a complete or exhaustive list of available
alternative embodiments, whether presently known or later
developed. Those skilled in the art may readily adopt one or more
of the inventive aspects, concepts or features into additional
embodiments and uses within the scope of the present inventions
even if such embodiments are not expressly disclosed herein.
Additionally, even though some features, concepts or aspects of the
inventions may be described herein as being a preferred arrangement
or method, such description is not intended to suggest that such
feature is required or necessary unless expressly so stated. Still
further, exemplary or representative values and ranges may be
included to assist in understanding the present disclosure;
however, such values and ranges are not to be construed in a
limiting sense and are intended to be critical values or ranges
only if so expressly stated. Moreover, while various aspects,
features and concepts may be expressly identified herein as being
inventive or forming part of an invention, such identification is
not intended to be exclusive, but rather there may be inventive
aspects, concepts and features that are fully described herein
without being expressly identified as such or as part of a specific
invention, the scope of the inventions instead being set forth in
the appended claims or the claims of related or continuing
applications. Descriptions of exemplary methods or processes are
not limited to inclusion of all steps as being required in all
cases, nor is the order that the steps are presented to be
construed as required or necessary unless expressly so stated.
[0014] With reference to FIG. 1, a welding system 10 is
schematically represented, and in this exemplary embodiment
includes a weld head 12 having an electrode 14. The inventive
aspects that are part of this disclosure may be used with many
kinds of welder power supplies and weld heads, for example, a weld
head such as model SWS-5H-C available from Swagelok Company,
Cleveland, Ohio. The weld head 12 may be manual or automatic and
typically includes or is associated with a fixture 13 that holds or
positions a workpiece WP near the electrode 14 for a welding
operation. For example, an orbital welder may include a weld head
15 that holds the electrode 14 (and motor to rotate the electrode)
and interfaces with the fixture 13 or holder that supports two tube
ends. The tube ends are typically clamped in end to end abutting
engagement with the abutting ends being the weld site W proximate
the electrode 14 for welding.
[0015] The welding system 10 further includes a welder power supply
16, for example, model SWS-M100-1-1 available from Swagelok
Company, Cleveland, Ohio. The power supply 16 provides the
appropriate voltage and current profiles to carry out each welding
operation. The welder power supply 16 typically provides the power
needed after the weld arc is struck, and may also include or be
operable with an arc start circuit. A control system 20 carries out
overall control of a welding operating including control of the
power supply 16, electrode drive motor of the weld head, purge
control and so on. An exemplary control system 20 may be model M100
available from Swagelok Company, Cleveland, Ohio. Any suitable
control arrangement may be used for the control system 20,
including but not limited to software based microprocessors or
microcontrollers, PLC type systems, discrete circuits and so on to
name a few examples. Functionally, the arc start circuit provides
high voltage, low current power, such as a pulse, that breaks down
or ionizes the gap G between the electrode 14 and the workpiece WP.
Once the arc is struck, the arc start circuit may be disabled and
the power supply 16 used to provide low voltage, high current power
to maintain the arc during a welding operation. The supply 16 may
be connected to the electrode 14 and a negative reference or ground
for the workpiece using electrical cables 17.
[0016] A general power source 22, such as conventional AC wall
power, is used to power the power supply 16 and the overall system
10. Some welding systems 10 may include or use a portable supply or
generator for the source 22. Thus the supply 22 may be conventional
110 VAC, 220 VAC or other power input sufficient to power the
system 10. The system 10 may also operate from a DC source.
[0017] In accordance with an inventive aspect of the disclosure, an
automatic flow control function may be realized, for example, with
one or more mass flow controllers (MFCs) or other suitable
arrangement to achieve automatic flow control functionality, to
effect automatic purge control. A suitable device for automatic
flow control functionality is a mass flow controller such as the
GFC Series, available from AALBORG, Orangeburg, N.Y. In the
exemplary embodiment, a first MFC may be used for OD purge control
24 and a second MFC may be used for ID purge control 26. The OD
purge control 24 receives at an inlet 29 purge gas from a first
source connection 28 and the ID purge control 26 receives at an
inlet 31 purge gas from a second source connection 30. Both purge
controls may alternatively be connected to a common purge gas
inlet. Also, in alternative embodiments a welding system 10 may
only need one of the two purge controls, or may have them both
present but only use one of them during a particular welding
operation.
[0018] The purge gas flowing out of the OD purge control 24 flows
through a connection or hose 32 to the weld head 12 so as to flow
along the outside surface and surrounding volume at the weld site
W. The purge gas flowing out of the ID purge control 26 flows
through a connector or hose 34 to the workpiece WP so as to flow
through the interior volume of the workpieces being welded
together.
[0019] The use of automatic flow control functions as taught
herein, such as with an MFC for example, for purge control allows
for automatic purge gas flow profiles and control, in contrast to
prior systems that used manual valve adjustments and flow meters.
These prior systems require substantial set-up time in order to
achieve the proper purge gas flow for a particular welding
operation. By automatic purge control is simply meant that the
purge flow profile and sequences may be carried out electronically,
for example, by programming the control system 20, rather than
having to manually adjust flow valves and observe flow rates on a
flow meter. A separate control function may alternatively be used
for automatic purge control, rather than the welder control system
20. In such an alternative embodiment, the purge control function
may send a signal to the control system 20 indicating that purging
has been properly initiated prior to enabling a welding operation.
The term "automatic" is not intended to exclude the option of
allowing an operator to input changes to the purge sequence. The
term automatic purge control is intended to include the options of
flow control as well as pressure control via flow control. Changing
the purge gas flow profile may be necessary, for example, when a
welding operation is changed. The use of an automatic purge control
also facilitates use of dynamic purge sequences, meaning that the
purge gas flow rate and/or pressure may be adjusted or changed over
the course of a welding operation, as well as during pre-weld and
post-weld purging operations.
[0020] Prior systems typically have the purge system separate from
the welder and power supply so that an operator could forget to
perform the purging operation. The use of automatic purge control
in accordance with the inventions herein overcomes many issues with
prior manual systems because the control system 20 may easily be
programmed to execute various purge flow profiles before, during
and after welding. The automatic purge control, for example, allows
for feedback to the control system 20 so that the welding system 10
may be inhibited in the absence of adequate purging.
[0021] For OD purge, purge gas flow rate is a significant
consideration. Sufficient flow must be present to prevent
oxidation, but too high a flow can cause the arc to "bend" or even
extinguish. The use of automatic flow control functionality allows
for automatic control of the OD purge gas flow rate. The flow rate
used for specific welding operations may be empirically
determined.
[0022] For ID purge, in addition to flow rate it may be desirable
in some cases to maintain pressure inside the workpieces
particularly at the weld site. The inner pressure may be used, for
example, to offset the effect of gravity on the weld puddle. Also,
as a welding operation proceeds, internal pressure can build due to
a decrease in purge gas "venting" through the weldment. The use of
automatic flow control function allows for automated or dynamic
internal pressure adjustment as a function of flow rate. The flow
rate set point for achieving desired pressure within the workpieces
may be empirically determined. For example, a T-connection (not
shown) may be inserted at the weld site as part of a calibration
procedure. A magnahelic pressure sensor (not shown) may be inserted
into the T-connection to sense pressure at different flow rates
from the corresponding MFC. The T-connection is then removed and
the welding operations can be performed, with the control system 20
storing relationships between commanded flow rates and desired
internal pressure readings.
[0023] For both ID purge control and OD purge control it may be
desirable to have an increased purge gas flow rate prior to a
welding operation in order to minimize or reduce purging time.
Also, after a welding operation is completed, it may be desirable
to again have an increased purge gas flow rate to reduce purge
time, cool the weld and minimize oxidation. For both scenarios, the
use of automatic purge control such as with an MFC device, for
example, allows for automatic and precise dynamic control and
change of the purge gas flow rates, which in prior systems would be
time consuming and manually performed, and in many cases not even
possible.
[0024] With continued reference to FIG. 1, in another embodiment,
dynamic flow control may be realized on a more real-time basis, as
distinguished from empirically predetermined flow rate versus
pressure profiles. Such dynamic flow control may be used for
dynamic purge control, especially with respect to ID purge control.
As noted herein above, ID purge gas pressure typically varies
during a welding operation because venting decreases as the
weldment forms. In accordance with another inventive aspect of this
disclosure, dynamic purge control may be realized by the use of
pressure sensing in combination with automatic flow rate control as
described herein above. By dynamic is simply meant that a purge gas
flow may be adjusted on a real time or near real time basis in
response to a sensed condition, such as for example, pressure at
the weld site.
[0025] In accordance with this aspect, a pressure transducer 50 or
other pressure sensing arrangement may be disposed near the weld
site W (such as with a T-connection as noted herein above) so as to
sense the ID purge gas pressure prior to a welding operation. The
flow rate of various pressures can then be determined, much the
same way as using a magnahelic as described above. This transducer
50 is then removed for a welding operation. A second pressure
transducer 52 or other pressure sensing arrangement may be disposed
along the flow path between the MFC ID 26 and the welder, such as
near an outlet of the MFC 26. During a welding operation, the
control system 20 monitors the pressure sensor 52 which will detect
dynamic pressure changes as the welding operation is performed. The
control system 20 in response to these pressure changes can
dynamically adjust the flow rate of purge gas from the MFC 26 to
maintain a desired ID pressure. In some cases, the pressure sensed
at the MFC outlet may not be the same pressure at the weld site W
due to pressure drop or flow resistance along the flow path. These
variations can easily be determined during calibration while
profiling the flow versus pressure characteristics with the first
transducer 50, and used as an adjustment factor during a welding
operation.
[0026] With reference to FIG. 3, in accordance with another
inventive aspect of the disclosure, the use of automatic purge
controls allows for the purge function to be incorporated with the
power supply into a single and preferably portable assembly. For
example, a housing 40 (which may for example be portable with use
of a handle 41 for example) encloses the purge controls 24, 26 as
well as the power supply 16 and the control system 20. An operator
may simply plug in the supply 16 to an outlet 22, connect gas lines
(not shown) between the purge gas connections 28, 30 and purge gas
supply tanks (not shown), connect the electrical cable 17 between
the power supply output connectors 19a, 19b and the weld head 12,
and run the purge lines 32, 34 to the weld head 12. The control
system 20 may be programmed to check that there is the correct
purge flow to the welder prior to allowing an arc to be struck.
This avoids an operator forgetting to connect and purge the system
properly prior to welding. In this manner, the system 10 can
self-check for proper purging, whereas in prior systems the purge
operation was a separate stand alone assembly, with an operator
using manual purging operations that are separate and independent
from the power system so that purging errors could occur without a
disable of the weld system.
[0027] FIG. 2 illustrates an exemplary functional flow chart for an
exemplary purge operation facilitated by use of the automatic purge
controls.
[0028] At step 100 the control system 20 obtains either from a
memory or a user input the ID and OD purge set points for a
selected welding operation. For example, a look up table may be
used to store different flow set points for ID and OD purge during
different welding operations. At steps 102 and 104, increased purge
flow rates may be used as discussed above. At step 106, reduce
purge flows are used during a welding operation. These flow rates
are controlled at steps 108, 110 by control 20 interfacing with the
MFC devices. At step 112 the welding operation is completed. At
steps 114 and 116, increased purge flow rates may be used, again as
discussed above. Although not illustrated in FIG. 2, the control
system 20 may execute a routine to determine that the purge system
is functioning properly prior to enabling the weld system to
operate.
[0029] 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.
* * * * *