Note: Descriptions are shown in the official language in which they were submitted.
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PROTECTIVE NOZZLE FOR A LASER CAMERA
FIELD OF THE INVENTION
The present invention relates to a protective nozzle for a laser camera for
example as
used in the welding industry and often innerly cooled by pressurized air, and
more
particularly to a protective nozzle for protecting a frontal optical portion
of such a laser
camera, where lenses or windows for optical sensors that need to be protected
against contamination such as welding fumes may be located.
BACKGROUND
A laser camera used for tracking, monitoring or inspection of laser or arc
welding has
one or more transparent windows or lenses that transmit optical signals in or
out of
the camera enclosure. Such a laser camera is often used in robotic processes
and
requires protection for long periods of welding against welding fumes that
could
contaminate the transparent windows or lenses. External air knifes or jets are
often
used to protect these windows or lenses against contaminating welding fumes or
other contamination. US patents Nos 4,859,829 (Dufour), 5,264,678 (Powell et
al.),
5,442,155 (Nihei et al.), 6,270,222 (Herpst) and 7,557,326 (Boillot et al.)
provide
examples of laser cameras of the prior art, some of which including protection
against
welding fumes. In the prior art, the camera windows or lenses are sometimes
protected by air jet covering only a partial portion of the aperture contour,
as
illustrated on Figure 7. In such prior art devices, air pressure is applied on
the internal
surface of a protective plate of the window and notches on the other side of
the
protective plate, covering only a part of the aperture contour, allow air to
escape
outside as depicted by the arrows in Figure. 7. Such a construction provides
only
partial protection of the window area and unsatisfactory long term protection,
especially for large and numerous apertures. Also, fluctuating air pressure
sometimes
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causes undesired vibration of the protective plate in the window and rapid
contamination and even detrimental suction of the contaminating fumes toward
the
optical sensors of the laser camera, especially when different plates are used
to
replace the initial plate.
SUMMARY
An object of the invention is to provide a protective nozzle for protecting a
frontal
optical portion of a laser camera, which overcomes the aforesaid drawbacks of
the
prior art.
Another object of the invention is to provide such a protective nozzle which,
when the
laser camera is innerly cooled by pressurized air, may operate from
pressurized air
coming from the laser camera.
Another object of the invention is to provide such a protective nozzle which
may have
a construction with a single transparent plate facilitating replacement of the
transparent plate when necessary.
According to an aspect of the invention, there is provided a protective nozzle
for
protecting a frontal optical portion of a laser camera, the protective nozzle
comprising:
a body attachable to the laser camera, the body having opposite front and back
sides and being sized and shaped to cover the frontal optical portion of the
laser
camera when attached thereto with the back side of the body in direction of
the laser
camera;
at least one aperture extending through the body between the front and back
sides;
a transparent plate extending crosswise to and blocking each aperture on the
back side of the body;
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an air inlet located on a side of the body for receiving pressurized air;
for each aperture, a contouring air pocket recessed in the back side of the
body under the transparent plate and extending around and spaced from the
aperture
to form a lip projecting around the aperture toward the transparent plate, the
lip
having a distal surface spaced from the transparent plate to define an air gap
for
escape of pressurized air from the contouring air pocket toward the aperture
in a form
of a centripetal air jet along the transparent plate; and
an air passage arrangement extending in the body from the air inlet to each
contouring air pocket.
The following provides an outline of certain possibly preferable or
advantageous
features of the invention which are to be considered non-restrictively and
which will
be more fully described hereinafter.
The clever design of the protective nozzle of the invention thus allows laser
camera
protection without involving air pressure applied on the internal side of a
transparent
plate protecting the laser camera, and needs no external air jet and
pressurized air
supply connection when the laser camera is innerly cooled by pressurized air.
The
integrated air jets are provided by internal passages and gaps that produce a
calibrated air jet all around each optical aperture and deviate fumes or other
contaminants out of and away from the aperture areas. The protective nozzle
according to the invention offers many advantages such as compactness, no
external
pressurized air supply connection necessity when the laser camera is innerly
cooled
by pressurized air, better protection against welding fume contamination even
when
the apertures are large and multiple, longer use between replacements of the
transparent plate, and fast and easy replacement of the plate when necessary.
Another advantage is that a lower flow rate of pressurized air may be used,
which is
more economical and better for the welding, especially the welding of
aluminum.
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BRIEF DESCRIPTION OF THE DRAWINGS
A detailed description of preferred embodiments will be given herein below
with
reference to the following drawings:
Figure 1 is an exploded view of a laser camera provided with a protective
nozzle
according to an embodiment of the invention.
Figure 2 is a back side perspective view of a protective nozzle according to
an
embodiment of the invention.
Figure 3 is an exploded side elevation perspective view of a protective nozzle
according to an embodiment of the invention.
Figure 4 is a back side view of a protective nozzle according to an embodiment
of the
invention.
Figure 5 is a cross-sectional view of the protective nozzle taken along the
line 4-4 of
Figure 4.
Figure 6 is a schematic cross-sectional view of a protective nozzle
illustrating air flow
in the protective nozzle according to the invention.
Figure 7 is a schematic cross-sectional view of a protective arrangement of
the prior
art illustrating air flow in such arrangement.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figure 1, there is shown a protective nozzle 2 for protecting a
frontal
optical portion 4 of a laser camera 6 innerly cooled by pressurized air as
received
through a side air inlet 8. The laser camera 6 may have an enclosure 10
provided
with a top lid 12 that can be unscrewed to have access to optical sensors and
other
components (not shown) inside the laser camera 6. The frontal optical portion
4 may
be provided with lenses or other optical devices 22 such as LEDs or simple
holes for
allowing passage of light or radiations as needed for the operation of the
laser
camera 6.
The protective nozzle 2 has a body 14 attachable to the laser camera 6, for
example
using a knurled bolt 16 screwable into a threaded hole 60 through the
enclosure 10 of
the laser camera 6. Other fastening arrangements may be used if desired, like
clipping, clamping or bracket arrangements (not shown) depending on the shape
and
configuration of the laser camera 6 and of the protective nozzle 2 whose body
14 has
opposite front and back sides 18, 20 and is sized and shaped to cover the
frontal
optical portion 4 of the laser camera 6 when attached to it with the back side
20 of the
body 14 in direction of the laser camera 6.
The protective nozzle 2 has one or multiple apertures extending through the
body
between the front and back sides 18, 20. In the illustrated case, the
protective nozzle
has five apertures 24 for the five lenses or optical devices 22. A transparent
plate 26
extends crosswise to and blocks each aperture 24 on the back side 20 of the
body
14.
Referring to Figures 2, 3 and 4, an air inlet 28 is located on the back side
20 of the
body 14 for receiving pressurized air from the laser camera 6 (shown in Figure
1). For
each aperture 24, a contouring air pocket 30 is recessed in the back side 20
of the
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body 14 under the transparent plate 26 (as better seen in Figures 5 and 6) and
extending around and spaced from the aperture 24 to form a lip 32 projecting
around
the aperture 24 toward the transparent plate 26.
Referring to Figures 5 and 6, each lip 32 has a distal surface 34 spaced from
the
transparent plate 26 to define an air gap 36 (as best shown in Figure 6) for
escape of
pressurized air from the contouring air pocket 30 toward the aperture 24 in a
form of a
centripetal air jet along the transparent plate 26 as depicted by arrows 38 as
shown in
Figure 6. The contouring air pockets 30 and/or the lips 32 may extend fully
around the
apertures 24, i.e. around the whole peripheries of the apertures 24, or may
extend
discontinuously around the apertures 24 if desired provided that the resulting
arrangements form gaps 36 that produce the centripetal air jets along the
transparent
plate 26 where it blocks the apertures 24.
Referring to Figures 4 and 6, an air passage arrangement 40 extends in the
body 14
from the air inlet 28 (shown in Figure 4) to each contouring air pocket 30.
The air
passage arrangement 40 may take the form of an elongated air passage 42 as
shown
in staple lines in Figure 4, longitudinally extending within the body 14. The
elongated
air passage 42 has an opening defining the air inlet 28 and openings defining
air
outlets 44 feeding respective contouring air pockets 30. The elongated air
passage 42
may be bored from a lateral side of the body 14, a resulting bore opening in
the lateral
side being then closed with a stopper element 46 (as shown in Figure 1) such
as a
set screw that may be screwed or otherwise fastened to the body 14. Likewise,
the
openings defining the air outlets 44 may be bored from the back side 20 of the
body
14. In such configuration, the elongated air passage 42 has a generally
straight
course and the air outlets 44 are aligned with one another. The air passage
arrangement 40 may have other suitable configurations depending for example on
the
locations of the apertures 24, and may be formed in other ways for example by
molding in the case where the body 14 is made of assembled parts.
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The air inlet 28 may be located on another side of the body 14 if desired, for
example
at the location of the stopper element 46 which then would be removed or not
used.
In such a case, an external air supply connection such as with a hose (not
shown)
may be used to bring pressurized air from the laser camera 6 or from another
pressurized air supply source (not shown) to the air inlet 28.
Referring to Figure 4, the contouring air pockets 30 may have widening
sections
receiving the respective air outlets 44 of the elongated air passage 40 for
example to
facilitate a boring of the outlets 44 or for better distribution of the
pressurized air in the
contouring air pockets 30. Some of the apertures 24 may share a common
contouring
air pocket 30, particularly when the apertures 24 are smaller compared to the
other
ones in the body 14. Each air outlet 44 may have a diameter calibrated as
function of
a size and an area of the aperture 24 to be fed in pressurized air by the air
outlet 44.
The air pressure and the gap size may be calibrated on an empirical or a
theoretical
basis to ensure sufficient jet air speed to provide protection of the full
aperture areas.
Each air pocket 30 is thus fed by its own air inlet calibrated to insure
sufficient air
supply to provide adequate air jet velocity for each of the apertures 24 that
can be of
different size and area.
Referring to Figures 2 and 3, the back side 20 of the body 14 may conveniently
have
a recess sized and shaped to receive the transparent plate 26 in a blocking
position
of each aperture 24.
Referring to Figure 3, when the transparent plate 26 extends across most of
the back
side 20 of the body 14 and there is not enough space left to position the air
inlet 28 on
a side of the transparent plate 26, or depending on where the pressurized air
supply
48 (as shown in Figure 1) from the laser camera 6 is located, then the
transparent
plate 26 may have a hole 50 aligned with the air inlet 28, and the air inlet
28 may be
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provided with a tubular element 52 projecting through the hole 50, for
receiving
pressurized air from the air supply 48. The tubular element 52 may be provided
with a
gasket 54 for sealing engagement with the transparent plate 26 to prevent
leakage of
pressurized air. The tubular element 52 may have a surrounding groove 70 into
which
the gasket 54 partially engages for better gasket support and positioning
purposes.
When a knurled bolt 16 or like fastener element is used to attach the
protective nozzle
to the laser camera 6 (as shown in Figure 1), then the body 14 may have a hole
56
extending between the front and back sides 18, 20 and the transparent plate 26
may
also have a hole 58 aligned with the hole 56 in the body 14, so that the
knurled bolt
16 is insertable from the front side 18 of the body 14 into the holes 56, 58
in the body
14 and in the transparent plate 26 and can be screwed into the threaded hole
60 (as
shown in Figure 1) for screw attachment of the protective nozzle 2 to the
laser
camera 6.
The body 14 may be made of heat conducting material exhibiting resistance to
welding spatter adherence, welding heat and wear from welding spatters, such
as
copper or copper alloys. Other materials may be used if desired, depending on
the
environment where the laser camera 6 is to be used. The transparent plate 26
may
be made of polycarbonate material or other suitable transparent plastics or
materials,
for example glass, quartz, fused silica and sapphire. The transparent plate 26
may
advantageously be made in a single piece, for easier replacement when needed
and
economical reasons. However, it may be made of multiple pieces or in multiple
sections adjoining one another or not if desired.
The frontal optical portion 4 of the laser camera 6 may project from a front
side 62 of
the laser camera 6 (as shown in Figure 1). Then, the back side 20 of the body
14 may
have a peripheral flange 64 defining a housing for snugly receiving the
frontal optical
portion 4 of the laser camera 6. The housing may have a depth substantially
.. corresponding (with some play if desired) to a thickness of the transparent
plate 26
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and a thickness of the frontal optical portion 4 so that the transparent plate
26 is
sandwiched between a bottom surface 66 of the housing and a front surface 72
of the
frontal optical portion 4 (as shown in Figure 1) when the body 14 is attached
to the
laser camera 6. The housing may have a bottom peripheral shoulder 68 defining
a
space snugly receiving the transparent plate 26 and against which the front
surface
72 of the frontal optical portion 4 rests when the body 14 is attached to the
laser
camera 6.
Table I below provides an example of possible dimensions in millimeters (mm)
for
certain parts of the protective nozzle 2. The dimensions in table I are given
for
instructive purposes only and should not be considered as !imitative in any
way.
Table I
overall nozzle height: 32 mm
overall nozzle thickness: 14 mm
lip width: 0.8 mm
lip height: 1 mm
air gap height: 0.5 mm
air pocket width: 2.2 mm
air passage diameter: 3.2 mm
The invention thus enables integration, in a compact camera nozzle 2, of
various air
inlets/outlets 28, 44, passages 40, air pockets 30 and calibrated gaps 36
around
multiples apertures 24 between a single transparent plate 26 and a metal
supporting
body 14. A single central screw attachment 16, 60 can allow easy and fast
replacement of the single transparent plate 26. The apertures 24 may be
shielded by
full contouring air jets with air gaps 34 covering the full contours of the
apertures 24.
The protective air jets involve no application of air pressure on the internal
plate face,
a central or near central screw attachment 16, 60 can tightly held the plate
26 in
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place, and no air pressure fluctuations may cause fumes being sucked inside
the
apertures 24. In the case of a laser camera 6 innerly cooled by pressurized
air, air
supply coming from the pressurized camera enclosure 10 makes it unnecessary to
have separate external air supply (although such external air supply may be
used if
desired) while contributing to a neat and compact nozzle construction.
While embodiments of the invention have been illustrated in the accompanying
drawings and described above, it will be evident to those skilled in the art
that
modifications may be made therein without departing from the invention.
