U.S. patent application number 11/794731 was filed with the patent office on 2008-05-15 for coolant delivery.
This patent application is currently assigned to BAE SYSTEMS plc. Invention is credited to Peter Michael Devall, Stephen Arthur Morgan, Andrew David Wescott, Stewart Wynn Williams.
Application Number | 20080110196 11/794731 |
Document ID | / |
Family ID | 37857183 |
Filed Date | 2008-05-15 |
United States Patent
Application |
20080110196 |
Kind Code |
A1 |
Morgan; Stephen Arthur ; et
al. |
May 15, 2008 |
Coolant Delivery
Abstract
A coolant delivery device (100) comprises a coolant outlet (124)
and an exhaust (140, 160). The coolant outlet (124) is contained
within a housing (150) that has an opening provided with sealing
means (180), to which opening the coolant outlet (124) is arranged
to direct a coolant. In use of the device, coolant is delivered to
a surface to be cooled, and the coolant vaporises at the surface so
as to produce coolant gas. Since the sealing means (180), in use of
the device, form a seal between the housing (150) and the surface,
the coolant gas is constrained to escape the device through the
exhaust (140, 160), and does not disturb or disrupt the ambient
environment. The device is particularly useful for applying thermal
tensioning to welds through the delivery of a cryogenic spray to a
weld line.
Inventors: |
Morgan; Stephen Arthur;
(South Gloucestershire, GB) ; Wescott; Andrew David;
(South Gloucestershire, GB) ; Devall; Peter Michael;
(South Gloucestershire, GB) ; Williams; Stewart Wynn;
(Northamptonshire, GB) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
BAE SYSTEMS plc
London
GB
|
Family ID: |
37857183 |
Appl. No.: |
11/794731 |
Filed: |
December 15, 2006 |
PCT Filed: |
December 15, 2006 |
PCT NO: |
PCT/GB06/50458 |
371 Date: |
July 5, 2007 |
Current U.S.
Class: |
62/373 |
Current CPC
Class: |
B23K 37/003
20130101 |
Class at
Publication: |
62/373 |
International
Class: |
F25D 17/06 20060101
F25D017/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2006 |
EP |
06270003.4 |
Jan 11, 2006 |
GB |
0600439.4 |
Claims
1. A coolant delivery device comprising a coolant outlet within a
housing; the housing defining an opening and an exhaust, the
opening being provided with sealing means; and the coolant outlet
being arranged to direct a coolant towards the opening; such that,
in use of the device to deliver the coolant to a surface to be
cooled, at which surface the coolant vaporises to produce coolant
gas, the sealing means are operable to form a seal between the
housing and the surface, thereby constraining the coolant gas to
escape the device through the exhaust.
2. A device as claimed in claim 1 wherein the exhaust is
connectable to extraction means operable to extract coolant gas
from the device.
3. A device as claimed in claim or claim 2 wherein the exhaust
comprises primary and secondary exhausts.
4. A device as claimed in claim 3 wherein the sealing means
comprises first and second sealing members, each operable to form a
seal between the housing and the surface.
5. A device as claimed in claim 4 wherein the first and second
sealing members define a space therebetween, which space provides a
part of a passageway through which coolant gas can reach the
secondary exhaust.
6. A device as claimed in claim 5 wherein the second sealing member
encloses the first sealing member.
7. A device as claimed in claim 3 wherein the primary and secondary
exhausts are independently connectable to extraction means.
8. A device as claimed in claim 3 wherein the exhaust comprises
adjustment means operable to adjust the rate of extraction of
coolant gas from the device.
9. A device as claimed in claim 8 wherein the adjustment means are
provided in the primary exhaust.
10. A device as claimed in claim 1 wherein the housing is generally
cylindrical, and the exhaust and the sealing means are located at
opposite ends of the housing.
11. A device as claimed in claim 1 wherein the sealing means
comprises a flexible seal.
12. A device as claimed in claim 1 fabricated at least partly from
teflon.
13. A device as claimed in claim 1 adapted for use with welding
apparatus.
14. A device as claimed in claim 13 further comprising attachment
means for attaching the device to a welding rig comprising a
welding tool.
15. A device as claimed in claim 14 wherein the attachment means
are configured such that the position of the device relative to the
welding tool is adjustable.
16. A device as claimed in claim 1, wherein the coolant is a
cryogen.
17. (canceled)
18. A method of cooling a surface comprising the steps of:
delivering coolant to the surface, such that coolant gas evolves;
and extracting coolant gas from the vicinity of the surface through
an exhaust, so as to provide mitigation of the effects of leakage
of coolant gas into the ambient environment.
19. A method as claimed in claim 18, further comprising the step of
balancing the rate of delivery of coolant with the rate of
extraction of coolant gas so as to provide the mitigation.
20.-21. (canceled)
Description
[0001] This invention relates to improvements to coolant delivery.
More particularly, this invention relates to a coolant delivery
device for delivering coolant to a surface, thereby cooling the
surface. The invention also relates to a method of cooling a
surface. The inventive device and method are expected to find
application in the field of welding, amongst other fields.
[0002] The intense and localised thermal cycles applied to
workpieces during welding produce residual stresses that often lead
to distortion in welded components. Welding distortion is a
significant problem in the fabrication of welded structures, and
requires the application of expensive post-weld repair procedures
in order to correct distorted components. A recent report (Cole, B.
R., `Manufacturing Process Improvement, Reduction of Flame
Straightening`, The National Centre for Excellence in Metalworking
Technologies and The Navy Joining Centre Workshop, Aug. 29-30,
1995) estimates the total cost of correcting weld-induced
distortion to be .English Pound.2.2M per ship. A known solution to
this problem is the use of stress engineering techniques, such as
thermal tensioning, during welding. Thermal tensioning can be
applied using cryogenic liquid to induce local tensile stresses in
order to balance the stresses.
[0003] Unfortunately, application of thermal tensioning to welds
using cryogenic liquids is not currently practical. The intensity
of the cryogen spray required to produce the necessary cooling
effect is such that it disrupts most welding processes. For
example, EP 1,151,820 discloses a welding method using a liquid
cryogen spray to provide thermal tensioning. A spray of cryogen is
directed towards the weld line, and no attempt is made, when using
the apparatus disclosed, to contain evolved gas. The method is thus
unfortunately only applicable to friction stir welding, and not,
for example, to arc welding processes that are particularly
sensitive to the ambient gas environment, and therefore easily
disrupted where gas evolved from cryogen sprays is not suitably
contained.
[0004] Some trials have been performed using a barrier (such as a
metal plate) positioned between the spray and the welding source.
However, such barriers have not been successful, either at
containing the spray, or at containing evolved gas, and thus
disruption to the welding process still results. Even if a barrier
could be made effective, the intensity of cryogen spray required to
provide the necessary cooling would be likely to result in molten
material being ejected from the weld line. Clearly, any such
process would be dangerous if applied in a manufacturing
environment. Thus it has previously been necessary to apply the
coolant cryogen from the opposite side of the workpiece to the
welding source. However, during the fabrication of welded
structures, the reverse side is often not accessible, and so such
techniques are not industrially practical.
[0005] There is therefore a need for an improved method of
delivering a coolant to a surface, and an improved coolant delivery
device, that avoid, or at least reduces the effects of, some of the
above-mentioned problems. Accordingly it is an object of the
present invention to provide a coolant delivery device, and a
method of cooling, that enable coolant to be delivered to a surface
in a manner which does not disrupt or significantly disturb the
ambient environment of the device. More particularly, it is an
object of the invention to provide a coolant delivery device that
enables coolant to be delivered to a welded surface in a manner
which does not disrupt or significantly disturb the ambient welding
environment of the device. It is a further object of the invention
to provide a device that allows effective thermal tensioning to be
applied to any welding method.
[0006] In broad terms, the present invention resides in the concept
of providing a coolant delivery device, for delivering coolant to a
surface, that incorporates extraction means for extracting any gas
that evolves from the action of the coolant on the surface. By
extracting gas, it is ensured that the ambient external environment
is not affected by the cooling, and thus that the device can be
used in conjunction with a wide variety of welding devices. The
invention extends to the concept of providing a method of cooling
ensures that the ambient environment is not affected by the cooling
process.
[0007] In accordance with a first aspect of the present invention,
there is provided a coolant delivery device comprising a coolant
outlet within a housing; the housing defining an opening and an
exhaust, the opening being provided with sealing means; and the
coolant outlet being arranged to direct a coolant towards the
opening; such that, in use of the device to deliver the coolant to
a surface to be cooled, at which surface the coolant vaporises to
produce coolant gas, the sealing means are operable to form a seal
between the housing and the surface, thereby constraining the
coolant gas to escape the device through the exhaust. Since the
evolved gas can escape only through the exhaust, the external
environment is not affected by cooling applied using the coolant
delivery device. This is advantageous where the device is to be
used for applications such as the application of thermal tensioning
to the arc welding process, which is highly sensitive to the
ambient environment.
[0008] Preferably, the exhaust is connectable to extraction means
operable to extract coolant gas from the device. The device may
then be connected to extraction means, such as a vacuum pump, so
that the coolant gas can be extracted more rapidly.
[0009] Conveniently, the exhaust comprises primary and secondary
exhausts. The primary and secondary exhausts may be independently
connectable to extraction means. For example, if the extraction
means are provided by vacuum equipment, the exhausts may be
independently connected to the same vacuum pump, or may be
connected to separate vacuum pumps. Provision of both a primary and
a secondary exhaust enables the in-flow of coolant to the device to
be more easily balanced with the out-flow of coolant gas. Such flow
balancing advantageously ensures that leakage of coolant gas
through the sealing means is limited whilst efficient cooling is
maintained.
[0010] The sealing means optionally comprises first and second
sealing members, each operable to form a seal between the housing
and the surface. Preferably, the first and second sealing members
define a space therebetween, which space provides a part of a
passageway through which coolant gas can reach the secondary
exhaust. The secondary exhaust can then provide extraction power at
the surface, through the first sealing member. This reduces the
likelihood of coolant being extracted from the device directly
through the primary exhaust, before it reaches the surface, and
thus enables a high cooling efficiency to be achieved whilst
maintaining the seal between the device and the surface. In one
embodiment, the second sealing member encloses the first sealing
member. The sealing means may comprise a flexible seal. Flexible
seals provide a simple method of forming a seal between the surface
and the housing, whilst advantageously still allowing the device to
move along the surface without breaking the seal. For example, the
sealing means may comprise a PTFE flexible seal. PTFE,
advantageously, is suitable for use both at low temperatures (and
therefore can be used with cryogenic coolants) and at high
temperatures (and therefore can be placed in contact with a
just-welded, still-hot surface without incurring damage). PTFE is
therefore suitable for use where the device is to be used to
provide thermal tensioning to a weld. In accordance with one
preferred embodiment, the housing is generally cylindrical, and the
exhaust and the sealing means are located at opposite ends of the
housing.
[0011] Preferably, the exhaust comprises adjustment means operable
to adjust the rate of extraction of coolant gas from the device.
The adjustment means may be provided in the primary exhaust. Such
adjustment means may be a valve provided in the primary exhaust,
operable to choke the flow through the exhaust, or may simply be
arranged to allow a variable amount of air into the flow through
the exhaust. Advantageously, when adjustment means are present in
the exhaust, the rate of flow of coolant gas through the exhaust
can be varied. This enables the device to achieve the appropriate
rate of extraction of coolant gas over a range of values of coolant
in-flow rate. The adjustment means may alternatively be provided in
both the primary and the secondary exhausts, leading to greater
flexibility in the flow parameters, and thus enhanced
flexibility.
[0012] The cooling power exerted by the device, in use, may be
varied by changing the rate of in-flow of coolant to the device.
The height of the coolant outlet may also be adjustable, thereby
providing an alternative means of adjusting the cooling power.
[0013] Preferably, the coolant is a cryogen. Cryogens are able to
exert large cooling powers since they are ejected from the coolant
outlet at a low temperature. More preferably, the coolant comprises
liquid carbon dioxide. Liquid carbon dioxide is stored under
pressure, and, on entry into an atmospheric pressure environment,
solidifies. When impacting on the surface, the solid carbon dioxide
sublimes, thus absorbing a large latent heat. Carbon dioxide is
therefore an effective coolant. The device is optionally fabricated
at least partly from PTFE. PTFE is an appropriate material to use
in conjunction with cryogens.
[0014] Optionally, the device is adapted for use with welding
apparatus. The device may comprise attachment means for attaching
the device to a welding rig comprising a welding tool. A particular
benefit of the invention is that it may be easily retro-fitted to
existing welding rigs. The device is particularly useful in the
field of welding since it allows thermal tensioning to be
effectively applied to a weld, from the weld side of the workpieces
to be joined, without disrupting the welding process. Thus, through
use of the invention, thermal tensioning can be applied in an
industrially practical manner. In particular, arc-welding
processes, that are sensitive to the ambient atmosphere, are
expected to benefit from the invention, since it allows thermal
tensioning to be applied without coolant gas escaping into the
vicinity of the weld tool. Furthermore, the containment of the
cryogen spray combined with the extraction of the evolved gas has
been found to negate the problem of molten material being ejected
from the weld line.
[0015] The attachment means may be configured such that the
position of the device relative to the welding tool is adjustable.
The appropriate position of the device relative to the weld tool
will vary in dependence on the nature of the weld. By configuring
the attachment means such that this distance can be varied, the
device is made more flexible, and can be used to apply thermal
tensioning to a wider range of welds, and to a wider range of
welding processes.
[0016] According to a second aspect of the invention, there is
provided a method of cooling a surface comprising the steps of:
delivering coolant to the surface, such that coolant gas evolves;
and extracting coolant gas from the vicinity of the surface through
an exhaust, so as to provide mitigation of the effects of leakage
of coolant gas into the ambient environment. By extracting the
coolant gas from the vicinity of the surface, it is advantageously
ensured that the ambient environment is not affected by the coolant
delivery. The inventive method may therefore be applied to provide
thermal tensioning to arc welding processes. The method may further
comprise the step of balancing the rate of delivery of coolant with
the rate of extraction of coolant gas so as to provide the
mitigation. Such balancing can be accomplished, for example, by
varying the extraction power exerted through the exhaust, and
allows efficient cooling to be combined with minimal coolant gas
leakage for a given application. The invention extends to a welding
method comprising cooling the welded surface according to the above
method.
[0017] A preferred embodiment of the invention will now be
described with reference to the accompanying drawings in which:
[0018] FIG. 1 is a perspective view of a device according to a
first embodiment of the invention;
[0019] FIG. 2 is a cross sectional view of the device shown in FIG.
1;
[0020] FIG. 3 is a photograph of the device shown in FIGS. 1 and 2
in use with a welding tool;
[0021] FIG. 4 is a graph illustrating the variation in distortion
of welded panels with cooling power applied using a method in
accordance with an embodiment of the invention;
[0022] FIG. 5 is a photograph of a device according to a second
embodiment of the invention; and
[0023] FIGS. 6a and 6b are photographs of a device according to a
third embodiment of the invention.
[0024] Referring firstly to FIGS. 1 and 2, there is shown
schematically a coolant delivery device 100 according to a first
embodiment of the invention. FIG. 1 is a perspective view of the
device 100, and FIG. 2 is a cross-sectional view of the device 100.
Device 100 is intended to be used to cool a surface by delivering a
coolant that will vaporise on contact with the surface. Cooling
results primarily through the latent heat of vaporisation of the
coolant. Such coolants may be cryogenic fluids or solids. Device
100 is therefore made primarily from PTFE, a material that is
compatible with cryogenic materials that are typically at very low
temperatures. Solid carbon dioxide, for example, sublimes at
atmospheric pressure and 194.7 K. It also exhibits a large latent
heat and is therefore a particularly efficient coolant.
Furthermore, it may be stored, under pressure, as a liquid,
solidifying only on entry into an atmospheric pressure environment,
and thus it may be easily directed at the surface to be cooled.
[0025] Device 100 comprises a housing 150 that is generally
cylindrical, hollow, and open at both ends. Coolant enters the
device 100 through coolant inlet 120, which extends into the
interior of device 100 (as can be seen most clearly from FIG. 2)
and then axially within the device through centring rings 126,
before terminating at nozzle 124. Nozzle 124 ejects the coolant
towards one end of the device, at which end there is a seal 180. In
operation of the device 100, seal 180 forms a seal between the
device and the surface. The coolant, once ejected from the nozzle
124, moves towards the seal end of device 180, where it impacts the
surface. The coolant vaporises on contact with the surface, thereby
cooling the surface and evolving coolant gas.
[0026] The evolved coolant gas is unable to escape device 100 at
the seal end of the device due to the operation of seal 180.
Instead, coolant gas is substantially constrained to move to the
opposite end of the device, at which end is formed primary exhaust
140. Seal 180 in fact comprises two flexible seals: an inner
flexible seal 182 and an outer flexible seal 184 (shown in FIG. 2).
By using flexible seals, it is ensured that the device 100 can move
along a surface without breaking the seal between the device and
the surface. Inner and outer flexible seals 182 and 184 are
concentric, and together define an annular hollow space 104 (shown
in FIG. 2) in between them. The annular hollow space 104 extends
part way up the side of the device 100 to a secondary exhaust 160.
Inner brush seal 182 separates the lower part of the interior of
device 100 from the lower part of annular hollow space 104, whilst
outer brush seal 184 separates annular hollow space 104 from the
external environment. Both primary and secondary exhausts 140 and
160 are connectable to vacuum pumps (not shown), so that coolant
gas can be actively extracted from the device.
[0027] Device 100 is configured so that the coolant in-flow to the
device, through inlet 120 (shown by the inwardly directed arrows in
FIGS. 1 and 2), can be balanced with the coolant gas out-flow
through the primary and secondary exhausts (shown by the outwardly
directed arrows in FIGS. 1 and 2). This flow balancing is a key
property of device 100: if the extraction power is too great in
comparison to the coolant in-flow, efficient cooling is not
possible since the coolant is extracted from the device before it
reaches the surface. On the other hand, if the coolant in-flow is
too great in comparison to the extraction power, there will
inevitably be leakage of coolant gas through brush seals. When flow
balancing is achieved, efficient cooling is combined with minimal
leakage of coolant gas. Flow balancing is achieved by varying
appropriate flow parameters of the device 100.
[0028] The extraction power exerted through the primary exhaust 140
can be varied using collar 142. Collar 142 is provided with a
number of holes, as shown most clearly in FIG. 1, and is rotatable
such that the holes may be aligned to a varying extent with cut-out
parts of the upper section of the device 100. A variable amount of
air is thus let into the flow through the primary exhaust 140,
correspondingly reducing the extraction power exerted at the seal
end of the device 100. Flow balancing can thereby be achieved
through varying the position of collar 142. Provision of the
additional, secondary exhaust 160 enables flow balancing to be
achieved more easily. It is thought that this is because, by
providing an additional source of extraction power at the
to-be-cooled surface, the likelihood of coolant ejected from the
nozzle 124 escaping directly through the primary exhaust, without
impacting the surface, is lessened. In addition, by exerting
extraction power though the annular hollow space 104 surrounding
inner flexible seal 182, the likelihood of coolant gas leakage into
the external environment is also lessened: in effect, there is
provided a double-barrier (by inner and outer flexible seals 182
and 184) against coolant leakage. The extraction power exerted
through secondary exhaust 160 is also variable, independently of
the primary exhaust extraction power. This independence may be
obtained, for example, by choking the flow through the secondary
exhaust 160 to the required extent using a valve in the pumping
line (not shown).
[0029] In practice, flow balancing is achieved entirely through
altering the extraction power exerted through the primary and
secondary exhausts 140 and 160. Of course, other flow parameters
may also be varied. For example, the height of the coolant inlet
120, and thus the coolant nozzle 124, can be varied using sliding
height adjuster 122. Furthermore, the rate of coolant in-flow is
variable--either through altering the size of nozzle 124, through
use of a valve at the coolant inlet 120, or through altering the
pressure at which coolant is supplied to the device 100. However,
the height of the nozzle 124 and the rate of coolant in-flow are
determined by the cooling power required by a given application,
and so it is not usually possible to alter either of these
parameters in order to achieve flow balancing. In contrast,
altering the extraction power exerted though the primary and
secondary exhausts 140 and 160 does not alter the cooling power
exerted by the device, unless the primary exhaust extraction power
is sufficiently large to extract coolant from the device before it
reaches the surface.
[0030] Whilst coolant delivery devices in accordance with the
invention may be used in a wide variety of applications, device 100
is particularly suited to providing thermal tensioning to a weld.
As such, device 100 is provided with threaded inserts 110 for
attaching device 100 to a welding rig. Device 100 is, in such an
application, positioned approximately 60-90 mm behind the welding
tool or torch, and moves with the welding tool or torch along the
weld line as the welding process is carried out. Generally, the
higher the thermal input from the welding process, the greater the
separation required. The device 100 is attached to the welding rig
such that its position relative to the welding tool 300 can be
varied so as to optimise their separation. FIG. 3 is a photographic
image illustrating device 100 in situ attached to a MIG (metal
inert gas) welding tool 300, an arc-welding tool. In use, carbon
dioxide coolant is used, and the device 100 is adjusted to balance
the in-flow of coolant with the out-flow of vaporised carbon
dioxide. No carbon dioxide escapes into the ambient environment,
and therefore the welding process is not affected.
[0031] The results of the application of the thermal tensioning
process are illustrated in FIG. 4, which is a graph showing the
variation in distortion index (on the vertical axis) for three
different welded panels (labelled with reference numerals 401, 402,
and 403). The distortion index is a measure of the amount of
distortion present in a panel. Panels 401 and 402 have been welded
using device 100 to apply thermal tensioning to the weld, with a
higher cooling power being applied to panel 401 (through use of a
larger nozzle size, which permits a more rapid flow of coolant to
the welded workpiece surface). Panel 403 has been welded without
the application of thermal tensioning. As is seen, panel 403
exhibits the highest distortion index, whilst panels 402 and 401
exhibit progressively less distortion. Whilst some residual
distortion is present, even in panel 401, it is thought that this
could be eradicated by lessening the separation between the welding
torch and the device. In the early stage trials whose results are
shown here, this separation was limited to 95 mm minimum, in
comparison to an expected optimum separation of 60 mm.
[0032] A photograph of a coolant delivery device 500 according to a
second embodiment of the invention is shown in FIG. 5. The device
500 is very similar to the device 100 of the first embodiment of
the invention, and delivers coolant in the same way as is described
above in relation to the first embodiment of the invention. The
only difference between the device 500 and the device 100 is that
the head portion 510 of the device, which contacts the surface to
be cooled, is angled slightly relative to the main body 520 of the
device 500. In the example shown, the head portion 520 is angled at
approximately 30 degrees relative to the main body 520 of the
device. As can be seen from FIG. 5, this enables the separation
between the welding torch 550 and the coolant delivery device 500
to be lessened in comparison to the minimum possible with the
device 100 of the first embodiment of the invention. In the case of
the device 100, as can be seen from FIG. 3, other parts of the
welding rig prevent the coolant delivery device from being
positioned very closely adjacent to the welding torch: this problem
is avoided, in the case of the welding rig on which these tests
were carried out, by the slight angling of the head portion 510 of
the device 500 relative to the main body 520.
[0033] In the case of the arrangement shown in FIG. 5, the
separation between the device 500 and the welding torch is 60 mm.
This separation was chosen in light of the initial trials performed
using device 100, and was expected to result in significantly less
weld-induced distortion than that found using the device 100. It
was found that the distortion of panels welded using the device 500
in the welding rig shown was comparable to the distortion found in
plate material free from welds, demonstrating the successful
application of thermal tensioning to the arc-welding process. Those
skilled in the art will appreciate that similar optimisation of the
separation between coolant delivery device and welding torch could
be carried out for other welding tasks.
[0034] FIGS. 6a and 6b are side photographic views of a coolant
delivery device 600 in accordance with a third embodiment of the
invention intended for use with fillet welds rather than butt
welds. The device 600 is again very similar to the device 100 of
the first embodiment of the invention, and to the device 500 of the
second embodiment of the invention, and delivers coolant to a
surface in the same way as described above in relation to the first
embodiment of the invention. As in the case of the second
embodiment of the invention, the head portion 610 of the device 600
is angled slightly relative to the main body 620 of the device. The
only difference to the second embodiment of the invention is in the
part of the head portion 620 that contacts the surface to be
cooled: it is shaped to be conformal with the T-shape of a fillet
weld. A flexible seal is also present at the conformal part of the
head portion 620 in order to provide a seal between the device and
the surface to be cooled, although this is not shown in FIGS. 6a or
6b.
[0035] It is to be appreciated that the above described embodiments
are purely exemplary. As will be understood by those skilled in the
art, it is possible for a coolant delivery device according to the
invention to be made without, for example, means for adjusting the
height of the coolant outlet, or indeed without any of the
adjustment means included in device 100: in particular, where such
a device is to be used repetitively for a single task only, it may
be advantageous to produce a device specifically designed to
balance coolant in-flow and coolant gas out-flow for that single
task. It is noted also that any coolant may be used in conjunction
with device 100--for example, cryogens other than solid carbon
dioxide could be used, such as liquid nitrogen. Furthermore, whilst
it has been described above to use PTFE to fabricate the device
100, it will be understood by those skilled in the art that any
cryogen-compatible material could be used to fabricate the device.
Moreover, any flexible seal compatible with cryogenic conditions
could be used for seal 180.
[0036] Whilst devices according to the embodiments described above
are configured to deliver coolant to a planar surface or a surface
incorporating a right angle such as may be the case where it is
desired to deliver coolant to a fillet weld, it is noted that the
device could be modified in order to deliver coolant to any shape
of surface. It is envisaged that one device could be provided with
means for connecting a variety of head portions, such that one
coolant delivery device could be used for a number of different
weld configurations. It is also envisaged that the device may be
adapted to provide a thermal tensioning mechanism appropriate for
use in any type of welding.
[0037] The above-described and other variations and modifications
are possible without departing from the scope of the invention,
which is defined in the accompanying claims. Furthermore, it is to
be understood that any feature described in relation to any one
embodiment may be used alone, or in combination with other features
described, and may also be used in combination with one or more
features of any other of the embodiments, or any combination of any
other of the embodiments.
* * * * *