Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE OF THE INVENTION:
Abrasive Blasting Assembly
FIELD OF THE INVENTION
The present invention relates to an abrasive blasting
assembly for use in abrasive blasting metal and other
substrates.
BACKGROUND OF THE INVENTION
The external surface of crude oil storage tanks and
other large steel surfaces are abrasive blasted prior to
painting and coating. Abrasive blasting is required in order
to provide cleanliness and anchor profile on the steel
substrate for the paint to adhere to. Abrasive blasting is
labour intensive and time consuming. Production is limited
to between 50 and 200 square feet per man hour; if the
abrasive blaster is well equipped and is accompanied by
adequate ground support.
2 0 g~u~gy OF THE INVENTION
The present invention is an abrasive blasting assembly
that provides a relatively high production method of abrasive
delivery.
According to the present invention there is provided an
abrasive assembly which includes a shaft support, with a
rotating shaft supported by the shaft support. The shaft has
an input end and an output end. Means is provided for
rotating the shaft. An abrasive media line is provided which
is adapted to deliver abrasive media to the input end of the
shaft. An air propellant line is provided which is adapted
to deliver air to the input end of the shaft. At least two
diverging outlet conduit are mounted at the output end of the
shaft and adapted to create a vortex effect upon rotation of
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the shaft during operation.
The above described multi-outlet design provides for
uniform high volume abrasive deliver at up to 150 pounds per
square inch (psi). The diverging outlet conduit create a
vortex effect, which amplifies the abrasive delivery while
reducing abrasive media consumption. It has been found that
abrasive consumption can be reduced to approximately 3.5
pounds per square foot, as compared to approximately 8 pounds
per square foot with conventional systems when preparing new
steel to commercial grade.
Although beneficial results may be obtained through the
use of the abrasive blasting assembly as described above,
even more beneficial results may be obtained when the
following optional features are incorporated into the
abrasive blasting assembly.
Even more beneficial results may be obtained when the
~0 diverging angle of the outlet conduit is adjustable. It is
preferred that the outlet conduit diverge by not less than
0.5 degrees and not more than 15 degrees. The degree of
divergence required to maintain the strongest vortex effect
depends upon the distance from the working surface that the
outlet conduit are positioned. The preferred working
distances are 2 feet and 15 feet. At the first distance of 2
feet, it has been found that an angle of divergence of 8 to
15 degrees brings the best results. At the second distance
of 15 feet, it has been found that an angle of divergence of
0.5 to 8 degrees brings the best results. All angles are
expressed in terms of divergence in relation to the
longitudinal axis of the rotating shaft.
Even more beneficial results may be obtained when a
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stationary pressurized delivery chamber is positioned at and
matingly engaged with the input end of the shaft. The
pressurization of the delivery chamber reduces abras~_ve wear
by equalizing backpressure. Abrasive wear may be even further
reduced through the use of a tapered wear sleeve which
extends from the pressurized delivery chamber into the input
end of the shaft. The tapered wear sleeve prevents abrasive
media from striking in the vicinity of the connection.
Even more beneficial results may be obtained when some
form of bearing or bearings are disposed between the shaft
support and the shaft.
There are various types of drive systems that can be
used to rotate the shaft. Beneficial results have been
obtained when the means for rotating the shaft includes a
drive motor having an output pulley, a circumferential input
pulley around the shaft, and a belt drive coupling extending
between the output pulley of the drive :motor and the input
pulley. The drive motor provides a motive force via the belt
drive coupling which rotates the shaft. It has been found
that rotational speeds of between 25 and 100 RPM are
sufficient to ensure that desired vortex effect is achieved.
Even more beneficial results may be obtained when a
transition coupler is provided between the output end of the
shaft and the outlet conduit. A divider is positioned in the
transition coupler to divide flow at the output end of the
shaft into two outlet streams. It has been found that the
use of the divider creates a media cushion which reduces wear
at the output end of the shaft and in the outlet conduit.
Even more beneficial results may be obtained when the
shaft support is mounted to an unmanned lifting apparatus
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which is operated by remote control. Conventional abrasive
blasting assemblies use compressed air, normally at 350 CFM,
to provide a nozzle pressure of about 100 to 110 PSI. Due to
weight and back pressure, the operation of each assembly
requires one man. The height of the storage tanks can exceed
60 feet. Each man must, therefore, be equipped with fall
arrest equipment. Working in close proximity to the abrasive
blasting, each man must be equipped with breathing apparatus
and protected against abrasive media ricochet by safety gear.
The above described abrasive blasting assembly is so
effective, in comparison with conventional abrasive blasting
assemblies, that it can be mounted on a lifting apparatus and
operated remotely.
BRIEF DESCRIPTION OF THE DRAinTINGS
These and other features of the invention will become
more apparent from the following description in which
reference is made to the appended drawings, the drawings are
for the purpose of illustration only and are not intended to
in any way limit the scope of the invention to the particular
embodiment or embodiments shown, wherein:
FIGURE 1 is a side elevation view, i.n section, of an
abrasive blasting assembly constructed in accordance with the
teachings of the present invention.
FIGURE 2 is a partially cut away exploded perspective
view of an input end of a rotating .shaft of the abrasive
blasting assembly illustrated in FIGURE 1-
FIGURE 3 is a side elevation view, in section, of the
input end of a rotating shaft of the abrasive blasting
assembly illustrated in FIGS 1.
FIGURE 4 is a partially cut away exploded perspective
view of an outlet end of the rotating shaft of the abrasive
blasting assembly illustrated in FIGURE 1-
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FIGURE 5 is a detailed perspective view of diverging
outlet conduit at the output end of the rotating shaft of the
abrasive blasting assembly illustrated in FIGURE 1-
FIGURE 6 is a perspective view showing unmanned remote
5 operation of the abrasive blasting assembly illustrated in
FIGURE 1
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment, an abrasive blasting assembly
generally identified by reference numeral 10, will now be
described with reference to FIGURES 1 through 6.
Referring to FIGURE to blasting assembly 10 has a shaft
support 12 that supports a rotating shaft 14 having an input
end 16 and an output end 18. Referring to FIGURES 2 and 3,
bearings 20 are disposed between shaft support 12 and shaft
14. Referring to FIGURE 1= a drive motor 22 is provided
which has an output pulley 24. Rotating shaft 14 is adapted
with a circumferential input pulley 26. A belt drive
coupling 28 extends between output pulley 24 and input pulley
26 such that drive motor 22 provides motive force to rotate
shaft 14.
Referring to FIGURE 2~ a stationary pressurized delivery
chamber 30 is positioned at and matingly engaged with input
end 16 of shaft 14. Referring to FIGURE 3. delivery chamber
is adapted with a tapered wear sleeve 32 which extends
into input end 16 of shaft 14. Referring to FIGURE 1. an
30 abrasive media line 34, adapted to deliver abrasive media,
and an air propellant line 36, adapted to deliver air, are in
connection to delivery chamber 30 at input end 16 of shaft
14. Referring to FIGURE 5. two diverging outlet conduit 38
are mounted at output end 18 of shaft 14. Conduit 38 are
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adapted to create a vortex effect upon _rotation of shaft 14.
A transition coupler 40 is positioned between output end 18
of shaft 14 and outlet conduit 38. Referring to gIG~ g,
Transition coupler 40 is adapted with an internal divider 42.
Divider 42 divides the flow at output end 18 of shaft 14 into
two outlet streams 44, as illustrated in gIG~ 5. Referring
to g=G~ 6, blasting assembly 10 is mcunted to a remote
control, unmanned lifting apparatus 46.
Operation:
The use and operation of abrasive blasting assembly 10
will now be described with reference to ~IG~S 1 through 6.
Referring to gIG~ 1, blasting assembly 10 is assembled and
configured such that abrasive media line 34, pressurized
delivery chamber 30, rotating shaft 14, transition coupler 40
and diverging outlet conduit 38 are in fluid connection with
each other. Air line 36 is connected to delivery chamber 30.
Referring to FIGURES 2 and g, shaft support 12 supports
shaft 14 upon bearings 20. Referring to FIGURE 5o in the
illustrated embodiment, outlet conduit 38 may be adjusted by
interchanging transition coupler 40 with another of varied
specification. Referring to FIGURE 1~ upon activation of
drive motor 22, motive force is applied through output pulley
24 through drive coupling 28 to input pulley 26 causing shaft
14 to rotate at variable speeds between 25 and 100 RPM.
Abrasive media is delivered through abrasive media line 34
and air is delivered through air propellant line 36 at
pressures of between 50 and 150 PSI. The abrasive media
stream merges with the air propellant stream in delivery
chamber 30. Referring to FzGURE 3~ the mixed abrasive
media/air propellant stream enters input end 16 of shaft 14
with tapered sleeve 32 serving to reduce abrasive wear.
Referring to FIGURE 4~ as abrasive medium passes through
output end 18, divider 42 divides the f_Low into one of outlet
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conduit 38. This also serves to create a media cushion,
reducing wear. Referring to ~gG~ 5, as shaft 14 rotates,
outlet conduit 38 also rotate and, in doing so, create a
vortex effect at outlet streams 44, amplifying the abrasive
delivery. Referring to ~IG~ 6, where abrasive conditioning
is to be applied to remote or perilous situations (the
exterior of a large storage tank is shown), mounting blasting
assembly 10 to unmanned lifting apparatus 46 allows remote
operation, avoiding the need for fall arrest precautions,
protection from ricochet and other problems associated with
direct human operation. This remote operation wou7_d not be
possible, were it not for the superior performance of
blasting assembly 10. Blasting assembly 10 delivers the
abrasive media a greater distance, over a wider area and at a
higher speed. The result is a more effective cleaning action
which actually requires less abrasive media than conventional
abrasive blasting assemblies.
In this patent document, the word "comprising" is used
in its non-limiting sense to mean that items following the
word are included, but items not specifically mentioned are
not excluded. A reference to an element by the indefinite
article "a" does not exclude the possibility that more than
one of the element is present, unless the context clearly
requires that there be one and only one of the elements.
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment
without departing from the spirit and scope of the invention
as hereinafter defined in the Claims.
