U.S. patent application number 10/778786 was filed with the patent office on 2004-08-19 for plasma mig welding.
This patent application is currently assigned to Illinois Tool Works Inc.. Invention is credited to Matus, Timm, Zhang, Lin.
Application Number | 20040159644 10/778786 |
Document ID | / |
Family ID | 28453742 |
Filed Date | 2004-08-19 |
United States Patent
Application |
20040159644 |
Kind Code |
A1 |
Zhang, Lin ; et al. |
August 19, 2004 |
Plasma mig welding
Abstract
Methods and apparatuses for plasma MIG welding or TIG MIG
welding are disclosed. They include a plasma or TIG torch for
following along a weld path by a MIG torch (or the order may be
reversed). A constant distance may be maintained between the
torches, and the angle of the torches, relative to the workpiece,
may vary. The MIG process is performed EP or EN in various
embodiments.
Inventors: |
Zhang, Lin; (Appleton,
WI) ; Matus, Timm; (Appleton, WI) |
Correspondence
Address: |
CORRIGAN LAW OFFICE
5 BRIARCLIFF CT
APPLETON
WI
54915
US
|
Assignee: |
Illinois Tool Works Inc.
|
Family ID: |
28453742 |
Appl. No.: |
10/778786 |
Filed: |
February 13, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10778786 |
Feb 13, 2004 |
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10114141 |
Apr 1, 2002 |
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6693252 |
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Current U.S.
Class: |
219/137R ;
219/74; 219/75 |
Current CPC
Class: |
B23K 10/006 20130101;
B23K 9/235 20130101; B23K 9/1068 20130101; B23K 2101/24
20180801 |
Class at
Publication: |
219/137.00R ;
219/075; 219/074 |
International
Class: |
B23K 009/16 |
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A method of plasma MIG welding comprising: creating a plasma arc
between a plasma torch and at least one workpiece; providing
relative movement of the plasma arc along a weld path; creating a
MIG arc between a MIG torch and the at least one workpiece;
providing movement of the MIG arc relative to the at least one
workpiece along the weld path; and wherein the MIG arc follows the
plasma arc along the weld path.
2. The method of claim 1, further comprising maintaining a constant
distance between the plasma torch and the MIG torch.
3. The method of claim 1, wherein the angle of the plasma arc is
between +10 degrees and -10.degree. degrees, where 0 degrees is
perpendicular.
4. The method of claim 3, wherein the angle of the plasma arc is
between perpendicular and +5 degrees, wherein +5 degrees is the
plasma arc angled toward the MIG arc.
5. The method of claim 3, wherein the angle of the MIG arc is
between +10 degrees and -45.degree. degrees, wherein -45 degrees is
the MIG arc angled toward the plasma arc.
6. The method of claim 4, wherein the angle of the plasma arc is
between 0 degrees and -30 degrees, wherein -30 degrees is the MIG
arc angled toward the plasma arc.
7. The method of claim 1, wherein the distance between the plasma
torch and the MIG torch is greater for faster movement along weld
path.
8. The method of claim 1, wherein the MIG process is EN.
9. The method of claim 1, wherein the MIG process is EP.
10. A system of plasma MIG welding comprising: a plasma torch; a
MIG torch; and wherein the MIG torch and the plasma torch are
mounted such that they are a fixed distance from one another.
11. The system of claim 10, wherein the plasma torch is mounted
such that the angle of the plasma torch relative to a workpiece is
between +10 degree and 10.degree. degrees, where 0 degrees is
perpendicular.
12. The system of claim 11, wherein the plasma torch is mounted
such that the angle of the plasma torch relative to the workpiece
is between perpendicular and +5 degrees, wherein +5 degrees is the
plasma torch angled toward the MIG torch.
13. The system of claim 11, wherein the MIG torch is mounted such
that the angle of the MIG arc relative to the workpiece is between
+10 degrees and -45.degree. degrees, wherein -45 degrees is the MIG
torch angled toward the plasma torch.
14. The system of claim 12, wherein the angle of the plasma torch
relative to the workpiece is between 0 degrees and -30 degrees,
wherein -30 degrees is the MIG torch angled toward the plasma
torch.
15. The system of claim 10, wherein the MIG torch has an EN
input.
16. The system of claim 10, wherein the MIG torch has an EP
input.
17. A system of plasma MIG welding comprising: means for creating a
plasma arc between a plasma torch and at least one workpiece;
plasma movement means for providing relative movement of the plasma
arc along a weld path, connected to the plasma torch; means for
creating a MIG arc between a MIG torch and the at least one
workpiece; and means for providing movement of the MIG arc relative
to the at least one workpiece along the weld path, connected to the
MIG torch and the plasma and connected to the plasma movement
means, whereby the MIG arc follows the plasma arc along the weld
path.
18. The system of claim 17, further comprising means for
maintaining a constant distance between the plasma torch and the
MIG torch, connected to the MIG torch and the plasma torch.
19. The system of claim 17, wherein the angle of the plasma torch
relative to the workpiece is between +10 degrees and -10.degree.
degrees, where 0 degrees is perpendicular.
20. The system of claim 19, wherein the angle of the plasma torch
relative to the workpiece is between perpendicular and +5 degrees,
wherein 5 degrees is the plasma arc angled toward the MIG
torch.
21. The system of claim 19, wherein the angle of the MIG torch
relative to the workpiece is between +10 degrees and -45.degree.
degrees, wherein -45 degrees is the MIG torch angled toward the
plasma torch.
22. The system of claim 20, wherein the angle of the plasma torch
relative to the workpiece is between 0 degrees and -30 degrees,
wherein -30 degrees is the MIG torch angled toward the plasma
torch.
23. The system of claim 17, wherein the means for creating a MIG
arc includes means for creating an EN arc.
24. The system of claim 17, wherein the means for creating a MIG
arc including means for creating an EP arc.
25. A system of plasma MIG welding comprising: a plasma torch; a
MIG torch; and means for mounting the MIG torch and the plasma
torch a fixed distance from one another.
26. A system for plasma MIG welding comprising: at least one power
source having a plasma power output, a MIG power output, and a
control input; and a controller operatively connected to the
control input.
27. The system of claim 26, wherein the at least one power source
further comprises at least one plasma power source connected to the
plasma power output, and a MIG power source connected to the MIG
power output.
28. The system of claim 27, wherein the controller comprises a
plasma controller connected to a control input on the plasma power
source and a MIG controller connected to a control input on the MIG
power source.
29. The system of claim 28, further comprising a plasma torch
connected to the plasma power output and a MIG torch connected to
the MIG power output.
30. The system of claim 29, wherein the plasma torch and the MIG
torch are mounted to one another.
31. A system for plasma MIG welding comprising: power means for
providing a plasma power output and a MIG power output; and control
means for controlling the power means, operatively connected to the
power means.
32. A product formed by the process of plasma MIG welding a
plurality of work pieces, wherein at least one of the plurality is
comprised of galvanized steel.
33. The process of claim 30 wherein the galvanized steel is G-60
galvanized steel.
34. The process of claim 30 wherein the galvanized steel is G-90
galvanized steel.
35. A method of TIG MIG welding comprising: creating a TIG arc
between a TIG torch and at least one workpiece; providing relative
movement of the TIG arc along a weld path; creating a MIG arc
between a MIG torch and the at least one workpiece; providing
movement of the MIG arc relative to the at least one workpiece
along the weld path; and wherein the MIG arc follows the TIG arc
along the weld path.
36. The method of claim 35, wherein the angle of the TIG arc is
between perpendicular and +5 degrees, wherein +5 degrees is the TIG
arc angled toward the MIG arc.
37. The method of claim 36, wherein the angle of the TIG arc is
between 0 degrees and -30 degrees, wherein 30 degrees is the MIG
arc angled toward the TIG arc.
38. A system of TIG MIG welding comprising: a TIG torch; a MIG
torch; and wherein the MIG torch and the TIG torch are mounted such
that they are a fixed distance from one another.
39. A system of TIG MIG welding comprising: means for creating a
TIG arc between a TIG torch and at least one workpiece; TIG
movement means for providing relative movement of the TIG arc along
a weld path, connected to the TIG torch; means for creating a MIG
arc between a MIG torch and the at least one workpiece; and means
for providing movement of the MIG arc relative to the at least one
workpiece along the weld path, connected to the MIG torch and the
TIG and connected to the TIG movement means, whereby the MIG arc
follows the TIG arc along the weld path.
40. The system of claim 39, further comprising means for
maintaining a constant distance between the TIG torch and the MIG
torch, connected to the MIG torch and the TIG torch.
41. A system of TIG MIG welding comprising: a TIG torch; a MIG
torch; and means for mounting the MIG torch and the TIG torch a
fixed distance from one another.
42. A system for TIG MIG welding comprising: at least one power
source having a TIG power output, a MIG power output, and a control
input; and a controller operatively connected to the control
input.
43. The system of claim 42, wherein the at least one power source
further comprises at least one TIG power source connected to the
TIG power output, and a MIG power source connected to the MIG power
output.
44. The system of claim 43, wherein the controller comprises a TIG
controller connected to a control input on the TIG power source and
a MIG controller connected. to a control input on the MIG power
source.
45. The system of claim 42, wherein the at least one power source
further comprises at least one TIG power source connected to the
TIG power output, and a MIG power source connected to provide the
MIG power output as EN.
46. The system of claim 42, wherein the at least one power source
further comprises at least one TIG power source connected to the
TIG power output, and a MIG power source connected to provide the
MIG power output as EP.
47. A product formed by the process of TIG MIG welding a plurality
of work pieces, wherein at least one of the plurality is comprised
of galvanized steel.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to the art of
welding and welding power supplies. More specifically, it relates
to welding with a plasma process or a TIG process and a MIG
process.
BACKGROUND OF THE INVENTION
[0002] There are a wide number of known welding processes used for
a variety of welding applications. Various processes have strengths
and weaknesses with respect to characteristics such as speed,
precision, workpiece composition, cost, flexibility, etc.
[0003] For example, MIG welding (metal inert gas welding) is
relatively fast, but somewhat imprecise. The process is fast
because, in part, a consumable wire electrode is used as a filler
metal. However, for some applications, such as welding galvanized
steel, MIG does not perform well, at least in part because the MIG
process, which is typically DC, does not, effectively prepare for
welding (or remove) the zinc on the steel. If not properly prepared
the zinc can vaporize during the welding process and cause bubbles
in the weld. Also, for some applications an even faster MIG process
is desired.
[0004] Another process, TIG welding, is precise and can work with
galvanized steel, but TIG is a relatively slow process. Thus, it is
often used for high-quality, low speed applications.
[0005] Plasma arc welding (PAW) is a welding process that also does
not lend itself readily to high speed welding. For example, PAW is
best performed at under 100 amps, and it is particularly useful for
welding under 20 amps and as low as 0.1 amp. If higher current is
needed, PAW is performed in a keyhole process, where the plasma gas
creates a hole in the workpiece, and molten metal flowing behind
the moving hole creates the weld bead.
[0006] TIG welding has been combined with plasma welding in plasma
TIG welding. Plasma TIG welding has been performed using a TIG
torch, followed by a plasma torch, followed by a TIG torch. Plasma
TIG welding is not well suited for galvanized steel, and TIG can be
slow.
[0007] A weld process that can be fast and precise is laser MIG
welding. This entails the simultaneous application of a laser beam
and a MIG arc on the weld. While the process may be fast, precise,
and useful on galvanized steel, it is expensive and may be
difficult to use.
[0008] Accordingly, a welding process that provides for relative
high speed, acceptable precision, without excess cost is desirable.
Preferably the process will weld galvanized steel.
SUMMARY OF THE PRESENT INVENTION
[0009] According to a first aspect of the invention a method of
plasma MIG welding includes creating a plasma arc and a MIG arc
between torches and a workpiece. There is relative movement between
the torches and a weld path.
[0010] A constant distance is maintained between the plasma torch
and the MIG torch in one embodiment.
[0011] According to a second aspect of the invention a system of
plasma MIG welding includes a plasma torch and a MIG torch. The MIG
torch and the plasma torch are mounted such that they are a fixed
distance from one another.
[0012] The angle of the plasma arc is between +10 degrees and -100
degrees, or between +5 degrees and perpendicular, and the angle of
the MIG torch is preferably between +10 degrees and -45.degree., or
between 0 degrees and -30 degrees, in various embodiments
[0013] The distance between the plasma torch and the MIG torch is
greater for faster movement along weld path in another
embodiment.
[0014] According to a third aspect of the invention a system for
plasma MIG welding includes at least one power source having a
plasma power output and a MIG power output. The power source also
has a control input and a controller is operatively connected to
the control input.
[0015] The power source includes a plasma power source and a MIG
power source, and the controller includes a plasma controller and a
MIG controller in various embodiments.
[0016] According to a fourth aspect of the invention a product is
formed by the process of plasma MIG welding a plurality of
workpieces. At least one of the workpieces is comprised of
galvanized steel, such as G-60 or G-90.
[0017] According to'a fifth aspect of the invention a method of TIG
MIG welding includes creating a TIG arc and a MIG arc between
torches and a workpiece. There is relevant movement between the
torches and a weld path.
[0018] A constant distance is maintained between the TIG torch and
the MIG torch in one embodiment.
[0019] According to another aspect of the invention a system of TIG
MIG welding includes a TIG torch and a MIG torch. The MIG torch and
the TIG torch are mounted such that they are a fixed distance from
one another.
[0020] The angle of the TIG arc is between +10 degrees and
-10.degree. degrees, or between +5 degrees and perpendicular, and
the angle of the MIG torch is between +10 degrees and -45.degree.,
or between 0 degrees and -30 degrees, in various embodiments
[0021] The distance between the TIG torch and the MIG torch is
greater for faster movement along weld path in another
embodiment.
[0022] According to yet another aspect of the invention a system
for TIG MIG welding includes at least one power source having a TIG
power output and a MIG power output. The power source also has a
control input and a controller is operatively connected to the
control input.
[0023] The power source includes a TIG power source and a MIG power
source, and the controller includes a TIG controller and a MIG
controller in other embodiments.
[0024] According to an eighth aspect of the invention a product is
formed by the process of TIG MIG welding a plurality of work
pieces. At least one of the workpieces is comprised of galvanized
steel, such as G-60 or G-90.
[0025] The MIG and/or TIG process is performed EP or EN in various
embodiments.
[0026] Other principal features and advantages of the invention
will become apparent to those skilled in the art upon review of the
following drawings, the detailed description and the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a diagram of a plasma MIG system in accordance
with the present invention; and
[0028] FIG. 2 is a diagram of a plasma torch mounted with a MIG
torch.
[0029] Before explaining at least one embodiment of the invention
in detail it is to be understood that the invention is not limited
in its application to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments or of being practiced or carried out
in various ways. Also, it is to be understood that the phraseology
and terminology employed herein is for the purpose of description
and should not be regarded as limiting. Like reference numerals are
used to indicate like components.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] While the present invention will be illustrated with
reference to a particular system and method using particular power
supplies, it should be understood at the outset that the invention
may be implemented using other embodiments, including other
components and other methods.
[0031] Generally, the invention is a method and apparatus for
plasma MIG welding. Plasma MIG welding, as used herein, includes a
welding process performed with a plasma arc and a MIG arc acting on
a common weld path, either sequentially in any order, or
simultaneously.
[0032] The preferred embodiment provides that a plasma torch is
mounted with a MIG torch, such that as the plasma torch is moved
along the weld path, the MIG torch trails by a small distance
({fraction (1/2)} inch, e.g.). Two power supplies are provided, one
for the plasma torch, and one for the MIG torch. The torches move
relative to the weld path on the workpiece, by moving the torches,
or moving the workpiece, or moving both torches and the workpiece.
Relative movement of a torch along a weld path, as used herein,
includes movement of the torch relative to the workpiece, and
either the workpiece can be moved, or the torch can be moved.
[0033] The present invention performs particularly well with
galvanized steel because the plasma arc prepares the zinc in the
steel for welding in advance of the MIG arc, and the MIG arc
provides the welding energy and filler metal. The speed of plasma
MIG can be 3-4 times the speed of MIG alone. Also the disadvantage
of MIG welding--difficulty in welding a workpiece that needs
cleaning or preparing, such as galvanized steel, is overcome.
[0034] A plasma MIG system 100 in accordance with the present
invention is shown in FIG. 1 and includes a power source 101, a
controller 106, a wire feeder 109, a plasma torch 111, and a MIG
torch 112. Power source 101 provides power to the torches, and wire
feeder 109 provides wire to MIG torch 112 (through the power
source). Controller 106 controls the process. The torches are moved
along a weld path on a workpiece 113 (in the direction of arrow
115) in the plasma MIG process.
[0035] The preferred embodiment provides that power source 101
includes a plasma power source 102, having a plasma power output
and a MIG power source 101, having a MIG power output. Plasma power
source 102 is controlled by a plasma controller 107, and MIG power
source 103 is controlled by a MIG controller 108. Power source, or
source of power, as used herein, includes the power circuitry such
as rectifiers, switches, transformers, SCRs, etc. that process and
provide the output power. Plasma power output, as used herein,
includes an output having sufficient power for use in a plasma
process (it may require transformation before being used in the
plasma process). MIG power output, as used herein, includes an
output having sufficient power for use in a MIG process (it may
require transformation before being used in the MIG process).
[0036] In various embodiments the components are housed separately,
or in various combinations. For example, in the preferred
embodiments plasma power source 102 and plasma controller 107 are
implemented with a Miller.RTM. Dynasty power supply (operated in a
dc mode), which provides a single housing for the plasma controller
and plasma power supply. Also, MIG power source 103 and MIG
controller 108 are implemented with a Miller Invision.RTM. power
supply (operated in a dc mode), which also provides a single
housing. Other embodiments entail a single power source that
provides power for both MIG and plasma, that may include two output
circuits.
[0037] The controllers may be combined on a single board, and the
entire system disposed in a single housing. Wire feeder 109 may be
part of the housing, or outside the housing. Also, controller 106
may directly control wire feeder 109, and wire feeder 109 provides
control signals to a control input on power source 103 (thus
controller 106 also controls power source 103). Controller, as used
herein, includes digital and analog circuitry, discrete or
integrated circuitry, microprocessors, DSPs, etc., and software,
hardware and firmware, located on one or more boards, used to
control a device such as a power supply. Control input, as used
herein, includes an input received that controls a power supply or
other component, such as a setpoint, gate-signals, phase control
signals, etc.
[0038] The invention is performed with the MIG process as EN
(electrode negative) or EP (electrode positive) in various
alternatives. Speed or quality of the weld for various applications
may be improved by appropriately selecting EP or EN. Using EP can
result in shunting (or partial shunting) of the arc from the
workpiece to the plasma torch. Therefore in at least some
embodiments EN will be preferred.
[0039] Referring now to FIG. 2, plasma torch 111 and MIG torch 112
are mounted on a bracket 201, which hold them a fixed distance
apart. As the welder or robot moves MIG torch 112 in the direction
of arrow 115, plasma torch 111 precedes it in the direction of
travel. Plasma torch 111 is shown perpendicular to workpiece 113 in
this embodiment. It is angled between +10 and -10 degrees, and
between +5 degrees and perpendicular, or at any other angle in
various embodiments. Angles are measured from the perpendicular,
and the angle is negative when the arc is angled in the direction
of travel.
[0040] MIG torch 112 is disposed at an angle .alpha., which as
negative 30 degrees in this embodiment. Other embodiments provide
for MIG torch 112 to be angled between +10 and -45 degrees, or at
any other angle.
[0041] When choosing the particular angle of plasma torch 111 and
MIG torch 112 the distance between the arcs, the interaction of the
arcs, and physical limitations of mounting the torches should be
considered. Generally, perpendicular arcs will have less
interaction, and should be able to weld at a higher speed. However,
the diameter of the torches (near bracket 201) may result in the
arcs being to far apart for high speed welding if the torches are
perpendicular.
[0042] Bracket 201 is chosen with the desired distance between arcs
in mind. Higher speed welding may be performed with the separation
greater, although it is generally useful to have the arcs as close
as possible without interaction. The distance is about {fraction
(1/2)} inch in the preferred embodiment, between 1/4 and 1 inch in
another embodiment, and any distance in other embodiments.
[0043] The output current is selected based on type of material,
speed, desired precision, etc. Generally, the plasma cone is larger
than the MIG cone for a given current. It may be desirable to
control the plasma cone to keep it narrow so that the current
density (and resultant heating and preparation of the zinc) is
greater.
[0044] The present invention is particularly well suited for
welding galvanized steel such as G-90 or G-60, because the plasma
arc prepares the zinc in the steel, allowing the MIG arc to weld at
a higher rate. G-60 and G-90 galvanized steel is steel wherein the
weight of zinc on the steel is 0.60 or 0.90 oz. per square foot,
respectively.
[0045] One alternative embodiment is a TIG-MIG system where TIG
torch is used to prepare the zinc, followed by a MIG torch that
weld the workpiece. Thus, in FIGS. 1 and 2 torch 111 maybe a TIG
torch, power source 102 maybe a TIG power source, and controller
107 maybe a TIG controller. Other alternatives include various
combinations of EP and EN, as desired for particular
applications.
[0046] Numerous modifications may be made to the present invention
which still fall within the intended scope hereof. Thus, it should
be apparent that there has been provided in accordance with the
present invention a method and apparatus for plasma MIG welding
that fully satisfies the objectives and advantages set forth above.
Although the invention has been described in conjunction with
specific embodiments thereof, it is evident that many alternatives,
modifications and variations will be apparent to those skilled in
the art. Accordingly, it is intended to embrace all such
alternatives, modifications and variations that fall within the
spirit and broad scope of the appended claims.
* * * * *