Note: Descriptions are shown in the official language in which they were submitted.
CA 02869673 2014-11-03
ROBOTIC WELDING ASSEMBLY
Technical Field
[0001] The present disclosure relates to robotic welding assemblies.
Summary
[0002] One aspect of the invention provides a robotic welding assembly
including
a base, a mast coupled at a first end to the base, a first horizontal arm
coupled at a first
end to a second end of the mast by a first slew drive, the first slew drive
for rotating the
first horizontal arm relative to the mast, a second horizontal arm coupled at
a first end to
a second end of the first horizontal arm by a second slew drive, the second
slew drive
for rotating the second horizontal arm relative to the first horizontal arm, a
vertical
actuator coupled to a second end of the second horizontal arm, a vertical arm
coupled
to the vertical actuator such that the vertical actuator moves the vertical
arm in a
substantially vertical direction, a robotic welding arm coupled to the
vertical actuator, the
robotic welding arm comprising a first rotary actuator having a first mounting
portion
coupled to the vertical arm and a first moveable portion rotatable relative to
the first
mounting portion about first axis, a second rotary actuator having a second
mounting
portion coupled to the first moveable portion of the first rotary actuator,
and a second
moveable portion rotatable relative to the second mounting portion about a
second axis
generally perpendicular to the first axis, a third rotary actuator having a
third mounting
portion coupled to the second moveable portion of the second rotary actuator,
and a
third moveable portion rotatable relative to the third mounting portion about
a third axis
generally perpendicular to the second axis, a welding torch holder coupled at
a first end
to the third rotary actuator, wherein a longitudinal axis of the welding torch
holder from
the first end to a second end of the welding torch holder is generally aligned
with the
third axis, and a welding torch coupled to the second end of the welding torch
holder.
[0003] Another aspect of the invention provides a sensor coupled to the
second
end of the welding torch holding for sensing a position of the welding torch
relative to a
pipe for positioning the welding torch.
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[0004] Another aspect of the invention provides that the robotic welding
arm
further comprises a camera for imaging a weld area.
[0005] Another aspect of the invention provides that the third actuator
assembly
is coupled to the first end of the welding torch holder.
[0006] Another aspect of the invention provides that the first axis is
substantially
parallel to the longitudinal axis of the vertical arm.
Drawings
[0007] The following figures set forth embodiments in which like
reference
numerals denote like parts. Embodiments are illustrated by way of example and
not by
way of limitation in the accompanying figures.
[0008] FIG. 1 is a perspective view of a robotic welding assembly
according to an
embodiment;
[0009] FIG. 2 is a perspective view of a robotic welding arm of the
robotic welding
assembly shown in FIG. 1;
[0010] FIG. 3 is a perspective view of a robotic welding arm of a robotic
welding
assembly according to another embodiment; and
[0011] FIG. 4 is a cross-section of two pipe segments welded together by
a
multiple pass welding process.
Detailed Description
[0012] The following describes a robotic welding assembly. For simplicity
and
clarity of illustration, reference numerals may be repeated among the figures
to indicate
corresponding or analogous elements. Numerous details are set forth to provide
an
understanding of the examples described herein. The examples may be practiced
without these details. In other instances, well-known methods, procedures, and
components are not described in detail to avoid obscuring the examples
described. The
description is not to be considered as limited to the scope of the examples
described
herein.
[0013] FIGS. 1 and 2 show a robotic welding assembly 100 according to one
embodiment. The robotic welding assembly is configured for installation in a
pipe
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fabrication facility for use in fabricating a pipe P comprising at least two
pipe sections
P1, P2 that are welding together along a seam S at an interface between the
two pipe
segments P1, P2. The two pipe sections P1, P2 are welded together at seam S
using a
process known as "spool welding".
[0014] The robotic welding assembly 100 includes a base 102 that is
supported
on a floor of the pipe fabrication facility. In some embodiments, the base 102
may be
coupled to the floor by, for example, bolts. In other embodiments, the base
102 may not
be coupled to the floor such that the base 102 may be moved to transport the
robotic
welding assembly 100 to different locations in the pipe fabrication facility.
[0015] A mast 104 is coupled to, and extends upwardly from, the base 102.
The
mast 104 may be supported by mast supports 106 extending outward from the mast
104 and coupled to the base 102 along the a lower edge of the mast support
106. The
mast 104 supports 106 increase the stability of the mast 104, inhibiting the
mast 104
from, for example, toppling over. In other embodiments, the base 102 may be
omitted
and the mast 104, and mast supports 106, may be coupled directly to the floor
of the
pipe fabrication facility.
[0016] The top of the mast 104 includes a first slew drive 108 that
couples the
mast 104 to a first horizontal arm 110 at a first end 112. The first slew
drive 108
rotationally moves the first horizontal arm 110 relative to the mast 104. The
first
horizontal arm 110 shown in FIG. 1 is a truss structure. In other embodiments,
other
structures for providing the first horizontal arm 110 may be utilized.
[0017] A second end 114 of the first horizontal arm 110 includes a second
slew
drive 116 that couples the first horizontal arm 110 to a second horizontal arm
118 at a
first end 120 of the second horizontal arm 118. The second slew drive 116
rotationally
moves the second horizontal arm 118 relative to the first horizontal arm 110.
The
second horizontal arm 118 shown in FIG. 1 is a truss structure. In other
embodiments,
other structures for providing the second horizontal arm 118 may be utilized.
[0018] In other embodiments, the first slew drive 108, the second slew
drive 116,
or both, shown in FIG. 1 may be replaced with a slew ring and disk mechanism
with a
braking system. In this embodiment, an operator moves either of the first
horizontal arm
110, second horizontal arm 118, or both by releasing pushing a button, or
activating
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other means, that releases the horizontal arm's braking system(s), causing the
horizontal arm(s) to be free to rotate. When the horizontal arm has reached
the desired
position, the operator releases the button, which engages the braking system,
stopping
rotation of the horizontal arm.
[0019] A second end 122 of the second horizontal arm 118 is coupled to a
vertical actuator 124. The vertical actuator 124 includes a cavity 126
extending through
the vertical actuator 124 from top to bottom. A vertical arm 128 is received
in the cavity
126 and is moved linearly in a substantially vertical direction by the
vertical actuator
124. The vertical actuator 124 may move the vertical arm 128 by a rack and
pinion
mechanism or by any other suitable mechanism. In some embodiments, the
vertical
actuator 124 may comprise a telescopic linear actuator.
[0020] A first end 130 of the vertical arm 128 is coupled to a robotic
welding arm
132. In the embodiment shown in FIG. 1, the first end 130 of the vertical arm
128 is the
end of the vertical arm 128 located below the vertical actuator 124 in order
to utilize the
robotic welding arm 132 for welding objects that are located below the height
of the
vertical actuator 124.
[0021] The first horizontal arm 110, the second horizontal arm 118, the
first slew
drive 108, and the second slew drive 116 are utilized to coarsely position the
robotic
welding arm 132 horizontally. The vertical actuator 124 and the vertical arm
128 are
utilized to coarsely position the robotic welding arm 132 vertically. Once the
robotic
welding arm 132 is coarsely positioned, the robotic welding arm may be finely
positioned as described in more detail below.
[0022] Referring now to FIG. 2, the robotic welding arm 132 of the
welding
assembly of FIG. 1 is shown. The robotic welding arm 132 includes a welding
arm
holder 134 that is coupled to the vertical arm 128 by a first rotary actuator
136, a second
rotary actuator 144, and a third rotary actuator 154.
[0023] The first rotary actuator 136 includes a first mounting portion
138 and a
first moveable portion 140. The first mounting portion 138 of the first rotary
actuator 136
couples to the first end 130 of the vertical arm 128. The first moveable
portion 140 of
the first rotary actuator 136 is rotatable relative the first mounting portion
138 about a
first axis 142.
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[0024] In the embodiment shown in FIG. 2, the first rotary actuator 136
is coupled
to the vertical arm 128 such that the first axis 142 is approximately parallel
to the
longitudinal axis of the vertical arm 128. The first axis 142 is offset from
the longitudinal
axis of the vertical arm 128.
[0025] The second rotary actuator 144 includes a second mounting portion
146
and a second moveable portion 148. The second mounting portion 146 of the
second
rotary actuator 144 couples to the first moveable portion 140 of the first
rotary actuator
136 such that the second rotary actuator 144 moves about the first axis 142
when the
first rotary actuator 136 is actuated.
[0026] The second moveable portion 148 of the second rotary actuator 144
is
rotatable relative to the second mounting portion 146 about a second axis 150.
The
second rotary actuator 144 is coupled to the first rotary actuator 136 such
that the
second axis 150 is substantially perpendicular the first axis 142.
[0027] The welding torch holder 134 is coupled at a first end 152 to the
second
rotary actuator 144 by a third rotary actuator 154. The third rotary actuator
154 includes
a third mounting portion 155 that couples the third rotary actuator 154 to the
second
moveable portion 148 of the second rotary actuator 144 such that the third
rotary
actuator 154 rotates about the second axis 150 when the second rotary actuator
144 is
actuated.
[0028] A third moveable portion 153 of the third rotary actuator 154
couples to the
first end 152 of the welding torch handle 134. The third moveable portion 153
is
rotatable relative to the third mounting portion 155 of the third rotary
actuator 154 about
a third axis 157 that is approximately parallel to the longitudinal axis of
the welding torch
holder 134 from the first end 152 to a second end 156.
[0029] The second end 156 of the welding torch holder 134 is coupled to a
welding torch 158.
[0030] In other embodiments, the first end 152 of the welding torch
holder 134
may be directly coupled to the second moveable portion 148 of the second
rotary
actuator 144, and the second end 156 of the welding torch holder 134 may be
coupled
to the welding torch 158 by the third rotary actuator 154. In this alternative
embodiment,
the welding torch 158 rotates relative to the welding torch holder 134 about
the third
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axis 157, and the welding torch holder 134 is in a fixed relation to the
second moveable
portion 148 of the second rotary actuator 144.
[0031] The welding torch 158 shown in FIGS. 1 and 2 includes a sensor
assembly 160 coupled to the welding torch 158 by the sensor mounting member
162.
The sensor mounting member 162 supports the sensor assembly 160 at a location
proximate a welding torch head 164 of the welding torch 158. The sensor
assembly
160 may comprise a laser sensor utilized to determine a distance between the
welding
head 164 and the object being welded, such as the seam S at the interface of
the pipe
segments P1, P2. In some embodiments, the sensor assembly 160 may comprise a
camera utilized to provide an image of the welding area to a control system
(not shown)
or to an operator.
[0032] In some embodiments, a voltage sensor may be utilized tracking the
welding path of the welding. In these embodiments, the distance may be
determined
based on the measured voltage changes in the welding arc.
[0033] Signals from the sensor assembly 160 may be sent to an automated
control system (not shown) that actuates the first rotary actuator 136, the
second rotary
actuator 144, and the third rotary actuator 154 based on the signals received
from the
sensor assembly 160 in order to finely position the welding torch. In other
embodiments, an operator may monitor the signals from the sensor assembly 160
and
manually control the first rotary actuator 136, the second rotary actuator
144, and the
third rotary actuator 154 in order to finely position the welding torch 158.
[0034] Referring to FIG. 3, another embodiment of a robotic welding arm
132 is
shown. In this embodiment, a wire-feeder system 300 is coupled to the robotic
welding
arm 132 by a wire-feeder bracket 302. The wire-feeder system 300 supplies wire
from
a wire source (not shown) to the welding torch 158.
[0035] In the embodiment shown in FIG. 3, the wire-feeder bracket 302 is
coupled to the first mounting portion 138 of the first rotary actuator 136. In
other
embodiments, the wire-feeder bracket 302 may be mounted, for example, on the
vertical arm 128, the vertical actuator 124, the second horizontal arm 118, or
any other
suitable location on the robotic welding assembly 100.
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[0036] In operation, the pipe P is positioned and supported by a pipe
positioner
(not shown). The pipe segments P1, P2 are positioned such that the
longitudinal axes
of the pipe segments P1, P2 are substantially aligned. Prior to welding, the
pipe
segments P1, P2 may be held together by clamps or straps or the like (not
shown). The
robotic welding arm 132 is coarsely positioned by actuating the first slew
drive 108, the
second slew drive 116, and the vertical actuator 124. Coarse positioning of
the robotic
arm 132 may be automated or may be carried out by an operator controlling the
first
slew drive 108, the second slew drive 116, and the vertical actuator 124. In
the above
described embodiment in which the first slew drive 108 and the second slew
drive 116
are replaced by slew ring and disk mechanisms and braking systems, coarse
positioning is carried out by an operator.
[0037] After coarse positioning, the welding torch 158 is finely
positioned
proximate to the seam S at the interface of the pipe segments P1, P2 by
actuating the
first rotary actuator 136, the second rotary actuator 144, and the third
rotary actuator
154. Fine positioning of the welding torch 158 may be automated or may be
carried out
by an operator controlling the first rotary actuator 136, the second rotary
actuator 144,
and the third rotary actuator 154.
[0038] After the welding torch 158 is finely positioned proximate the
seam S, the
pipe positioner rotates the pipe segments P1, P2 around the longitudinal axes
of the
pipe segments P1, P2. As the pipe segments P1, P2 rotate, the welding torch
158
welds the pipe segments P1, P2 together at the seam S. During welding, the
welding
torch arm 132 may be finely positioned to adjust for, for example, contour of
the
surfaces of the pipe segments P1, P2. Fine positioning during welding may be
automated based on the signals received from the sensor assembly 160.
[0039] The robotic welding assembly 100 may be utilized to weld the pipe
segments P1, P2 using a multiple pass welding process. FIG. 4 shows a cross
section
of a wall of pipe segments P1, P2 that have been welded along the seam S using
a
multiple pass welding process. Pipe segments P1, P2 have respective ends 402,
404
that are cut at an angle such that the seam S is narrower toward the inner
surfaces 406,
408 of the pipe segments P1, P2. During welding, the seam S is filled during
multiple
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passes of the welding torch 158, each pass depositing a weld 410a-d. The
multiple
pass weld shown in FIG. 4 includes approximately forty welds 410a-d.
[0040] In spool welding, multiple pass welding is utilized to provide a
uniform
weld with a constant parameter for each pass. In some embodiments, the robotic
welding assembly 100 may be configured to utilize a program to automatically
control
the robotic welding arm 132 to utilize a multiple pass welding process in
which welds
410a-d are made in different positions relative to each other in order to weld
the seam S
of the pipe segments P1, P2. The program may control the welding torch 158 to
carry
out each pass having a different specification including, for example,
voltage, wire
speed, and weld speed.
[0041] The present disclosure describes a robotic welding assembly for
use in
spool welding pipe segments in a pipe fabrication facility. The described
embodiments
are to be considered in all respects only as illustrative and not restrictive.
The scope of
the claims should not be limited by the embodiments set forth in the examples,
but
should be given the broadest interpretation consistent with the description as
a whole.
All changes that come with meaning and range of equivalency of the claims are
to be
embraced within their scope.
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