U.S. patent number 3,788,010 [Application Number 05/229,842] was granted by the patent office on 1974-01-29 for apparatus for treatment of vertically disposed surfaces.
This patent grant is currently assigned to Robert T. Nelson. Invention is credited to James R. Goff.
United States Patent |
3,788,010 |
Goff |
January 29, 1974 |
APPARATUS FOR TREATMENT OF VERTICALLY DISPOSED SURFACES
Abstract
A portable airless blasting head suitable for treatment of
vertically disposed surfaces is described. The blast head comprises
in combination an enclosure with an opening in one side adapted to
contact the surface to be treated, projecting means within the
enclosure for directing a stream of particulate abrasive material
through the opening in the enclosure onto the surface to be
treated, a resilient sealing means around the boundary of the
opening in the opening of the enclosure which contacts the surface
to be treated and retains the abrasive material in the apparatus,
and a recirculation means to return the particulate abrasive
material to the projecting means. Advantageously the apparatus of
the present invention is self-propelled.
Inventors: |
Goff; James R. (Oklahoma City,
OK) |
Assignee: |
Nelson; Robert T. (Oklahoma
City, OK)
|
Family
ID: |
22862894 |
Appl.
No.: |
05/229,842 |
Filed: |
February 28, 1972 |
Current U.S.
Class: |
451/88; 451/456;
451/92; 451/94 |
Current CPC
Class: |
B24C
3/062 (20130101); B24C 3/065 (20130101) |
Current International
Class: |
B24C
3/06 (20060101); B24C 3/00 (20060101); B24c
003/06 (); B24b 055/06 () |
Field of
Search: |
;51/8,9,12,270,273 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kelly; Donald G.
Assistant Examiner: Goldberg; Howard N.
Attorney, Agent or Firm: John W. Behringer et al.
Claims
It is claimed:
1. An apparatus for the treatment of surfaces with particulate
abrasive material which is projected at high velocity against the
surface comprising;
a. an enclosure in the form of a housing having an opening in one
wall;
b. a projecting means within the enclosure for propelling a stream
of particulate abrasive material through the opening in the
enclosure;
c. a resilient sealing means located on the wall of the enclosure
having the opening and being adapted to contact the surface to
establish a sealing relationship between the surface and the
enclosure;
d. a storage means for the particulate abrasive material which is
adapted to supply the projecting means with the particulate
abrasive material, said storage means defining an upper opening
within said enclosure;
e. a member defining a port in the upper portion of the enclosure
for drawing air from the enclosure, said member being located such
that the air from the enclosure is drawn across the opening defined
by the storage hopper to the port; and
f. a recirculation means adapted to collect the propelled
particulate abrasive material from a lower portion of the
enclosure, to convey the collected particulate abrasive material to
the upper portion of the enclosure, and to deliver the particulate
abrasive material at a delivery zone into the storage means,
wherein the delivery zone is located such that the air from the
enclosure which is drawn across the opening defined by storage
hopper, is drawn across the delivery zone.
2. The apparatus of claim 1 wherein the projecting means is a
centrifugal throwing wheel and wherein the centrifugal throwing
wheel is adapted to force circulation of air through the opening in
the enclosure and toward the surface.
3. The apparatus in claim 1 which is self-propelled and includes
therein a hoisting means to propel the apparatus in a vertical
direction.
4. The apparatus of claim 3 which includes a horizontal drive means
to propel the apparatus in a horizontal direction.
5. The apparatus of claim 1 wherein the opening in the enclosure in
oblong and has a major axis which extends vertically and wherein
the apparatus moves in a horizontal direction during treatment of
the surface.
6. The apparatus of claim 5 wherein the resilient sealing means in
a single resilient member extending outwardly from the
enclosure.
7. The apparatus of claim 1 wherein the vacuum port on the
enclosure is in communication with a fan means wherein the fan
means is located on the enclosure.
8. The apparatus of claim 7 wherein the fan means is a centrifugal
fan.
9. The apparatus of claim 1 wherein the recirculation means is a
conveyor means comprising an endless belt having attached thereon
at intervals scoop or bucket means which are adapted to collect the
particulate abrasive material and deliver the particulate abrasive
material to the storage means.
10. An apparatus for the treatment of surfaces with particulate
abrasive material which is projected at high velocity against the
surface comprising:
a. an enclosure in the form of a housing having an opening in one
wall;
b. a projecting means within the enclosure for propelling a stream
of particulate abrasive material through the opening in the
enclosure;
c. a resilient sealing means located on the wall of the enclosure
having the opening and being adapted to contact the surface to
establish a sealing relationship between the surface and the
enclosure;
d. a storage means for the particulate abrasive material which is
adapted to supply the projecting means with the particulate
abrasive material, said storage means defining an upper opening
within said enclosure, said upper opening having a portion which is
coterminous with a wall of the enclosure;
e. a member defining a port above the storage hopper in the wall of
the enclosure which is coterminous with the upper opening of the
storage hopper for drawing air from the enclosure;
f. a recirculation means adapted to collect the propelled
particulate abrasive material from a lower portion of the
enclosure, to convey the collected particulate abrasive material to
the upper portion of the enclosure, and to deliver the particulate
abrasive material at a delivery zone into the storage means,
wherein the delivery zone is located such that the air from the
enclosure which is drawn across the opening defined by storage
hopper, is drawn across the delivery zone.
11. The apparatus of claim 10 wherein the projecting means is a
centrifugal throwing wheel and wherein the centrifugal throwing
wheel is adapted to force circulation of air through the opening in
the enclosure and toward the surface.
12. The apparatus of claim 10 which is self-propelled and includes
therein a hoisting means and a horizontal drive means to propel the
apparatus in a vertical and a horizontal direction.
13. The apparatus of claim 10 wherein the resilient sealing means
is a single resilient member extending outwardly from the
enclosure.
14. The apparatus of claim 10 wherein the recirculation means is a
conveyor means comprising an endless belt having attached thereon
at intervals scoop or bucket means which are adapted to collect the
particulate abrasive material and deliver the particulate abrasive
material to the storage means.
Description
This invention relates to the treatment of vertically disposed
surfaces and more particularly it pertains to means for cleaning
such vertically disposed surfaces with particulate abrasive
material which is projected at high velocity against the surface to
be treated in order to remove rust, dirt, paint and other deposits
therefrom. This invention is directed to an apparatus which is
mobile and is continuously operable for cleaning surfaces such as
metal. In addition the novel apparatus is provided with means for
recovering the particulate abrasive material for reuse and means
for separating the particulate abrasive material from dust and
other light particles which result from the cleaning of the
surface.
Heretofore vertically disposed surfaces have commonly been air
blasted with crushed slag, sand and other abrasives as the abrasive
in order to provide the desired cleaning action. The crushed slag
abrasives, sand and other abrasives, however, are subject to
considerable disintegration and hence no attempts are made for its
recovery, and the abrasive is simply disposed of after a single
use. Air blasting has several other disadvantages. For instance,
the compressed air which is required is relatively expensive and
contains significant amounts of moisture, and even condensed water,
which tend to enhance reoxidation of treated surfaces before
protective coatings can be applied. Additionally, air blasting
equipment usually necessitates a crew of three men for the
operation of a single head, additional labor and equipment must be
used to remove the abrasive and disposal of the large amounts of
abrasive that is continuously being spent is an additional
consideration. Furthermore, air blasting can be a health hazard due
to the excessive amounts of dust created, and thus, protective
means must be provided to maintain the safety of personnel in the
area surrounding the air blasting operation.
As an alternative, it has been proposed to employ centrifugal
blasting wheels to propel the particulate abrasive material. One
system having a centrifugal blasting wheel is described in U.S.
Pat. No. 3,566,543, issued to Fogel. The patentee discloses a
blasting head comprising a housing, a centrifugal blasing wheel, an
opening in the housing through which the particulate abrasive is
projected onto the surface to be cleaned, and a pair of resilient
sealing members extending continuously around the opening in the
housing positioned so as to effect a seal between the surface to be
treated and the housing. However, several disadvantages exist in
the prior art device such as the necessity of replacement of the
pair of resilient seals which are subject to wearing due to their
contact with the surface undergoing cleaning, the extensive frame
required to support and move the blast head which substantially
reduces its portability, and the necessity of an operator to be
positioned relatively close to the blast head and thus often
expensive safety equipment must be incorporated into the blast
head.
The present invention provides a portable, continuously operable
surface treating apparatus for the cleaning of vertically disposed
surfaces. The novel apparatus is economical to manufacture and
simply constructed yet sturdy and durable upon extended use and
operates with relative freedom from wear. Furthermore, the
operation of the apparatus of this invention requires minimal
expense in labor and operating costs. A highly efficient means is
provided to prevent loss of particulate abrasive materials and for
the isolation of the particulate abrasive materials for recycling.
Also, means are provided by the present invention for removal of
dust and grit from the surface undergoing cleaning. Hence, this
invention can operate with almost complete elimination of the
passage of grit and dust to the atmosphere and thus can provide a
highly acceptable reduction in pollution normally attendant in the
use of conventional surface treating apparatus.
Importantly, the highly portable nature of the present invention
allows the apparatus without concern to geographic location of the
vertically disposed surface to be treated. The apparatus may be
employed over rough terrain, water, oil, etc. without the necessity
to provide support for a frame external from the surface being
treated. An extensive frame is not required for its operation.
Thus, the apparatus of the present invention may be set up for
operation quickly and early and its use is not prohibited or
restricted by the terrain surrounding the vertically disposed
surface to be treated. The apparatus of this invention is adapted
for uniform coverage of surfaces of variable or changing contour,
e.g., vertical curvature as well as horizontal curvature. The
apparatus of the present invention can be operated remotely, adding
greater safety to its operation.
This invention provides a mobile, continuously operable surface
treating apparatus useful for treating vertically disposed surface
to be treated, projecting means within the enclosure for directing
a stream of particulate abrasive material through said opening in
the enclosure onto the surface to be treated, a resilient sealing
means on the side of the enclosure having the opening which
contacts the surface to be treated and retains the abrasive
material in the enclosure and a recirculation means to return the
particulate abrasive material to the projecting means. The
apparatus of the present invention is advantageously
self-propelled; however, it is also possible to propel the
apparatus by other means.
The portable, continuously operable apparatus of the present
invention is generally easily adaptable to numerous uses and is
thus broadly practical and salable. For instance, the apparatus may
be used to clean the outer side walls of a ship's hull, large
conservation tanks for water, gas petroleum or other fluids or
solids, walls, exteriors of buildings and the like. The material
may be metal, concrete or other material where abrasive cleaning
may be desired.
For a fuller understanding of the invention, reference should be
made to the following detailed description, taken in connection
with the accompanying drawings, in which:
FIG. 1 is a perspective view of an apparatus of the present
invention;
FIG. 2 is a front elevational view with a break away section of the
apparatus; and
FIG. 3 is a schematic view of the apparatus in a suitable rigging
for operation to treat a vertically disposed surface.
With reference to FIG. 1, the apparatus, or blast head, is
generally indicated at 10. The blast head 10 comprises an enclosure
of housing 12 which defines a blast chamber having opening 14
through which particulate abrasive material is passed to contact
the surface to be treated. Opening 14 also receives rebounding
particles from the surface being treated and the scale, deposits or
other material being removed from the surface. The shape of the
opening may be of various configurations. Preferably, the opening
is oblong and in an oval or rectangular shape with the major axis
of the opening parallel to the projecting means, for example a
centrifugal throwing wheel, located in the housing and is more
preferably at or near perpendicular to the desired direction of
travel of the blast head. When, for example, the apparatus is
traveling in a horizontal direction, the major axis of the opening
is vertical.
Means are provided to effect a sealing relationship between the
surface being treated and the housing. The sealing means is
advantageously designed to abate the release of dust, scale or
other deposits to the atmosphere at the point of contact with the
surface and the loss of the particulate abrasive material from the
housing. The sealing means is preferably sufficiently resilient to
pass over obstructions present on the surface being treated and to
allow sealing over a moderately curved surface which is sufficient
to prevent release of dust or other material through gaps which
would otherwise be formed. The sealing means can be constructed out
of any suitable material such as natural rubbers, synthetic rubbers
and other elastomeric materials. For instance, polyurethane
elastomerics, butadiene rubbers and the like may be advantageously
employed. The sealing means 16 is depicted as extending from
boundary of opening 14, although it may be located in any manner on
the housing which would enable result to be obtained. The sealing
means can advantageously be of a design which enables easy
replacement of the sealing means on the housing. Beneficially, at
least the lower portion of the sealing means, that is, the section
of the sealing means which is positioned at the bottom of opening
14 during normal operation of the blasting head, projects
angularly, outwardly from the housing in a direction toward the
axis perpendicularly extending from the center of the plane of the
opening. The angular projection of the sealing means facilitates
the passage to any material deposited thereon to the housing.
Suitable sealing has been observed using a single resilient member
for the sealing means.
The movement of the blast head over the surface to be treated is
facilitated by casters 18 which are mounted on the housing. The
casters are rotatably mounted and are affixed to the housing by
clamps 20. Clamps 20 permit the casters to be positioned either a
greater or lesser distance from the housing, and the positioning of
the casters can be done manually or remotely. Thus, the working
compress upon sealing means 16 can easily be adjusted to provide a
seal which is sufficient for the nature of the surface being
treated. For example, a greater working compress will be necessary
when treating a rough, irregular surface in order to abate the
escape of dust and the like, whereas a relatively smooth surface
may require a substantially lesser working compress on the sealing
means. Additionally, the casters can be positioned to control the
attitude of the apparatus. It is readily seen that by the use of
casters, the use of a complex support frame means to position to
apparatus with respect to the surface being treated may not be
required. Nor is continual readjustment of the casters necessary to
provide a sufficient seal with the surface. The casters are shown
as being laterally positioned on the housing. Other placements of
the casters can be made; for instance, a set of three casters may
be employed which are placed on the housing in a triangular
configuration.
As shown in FIG. 1 is fan housing 22. While the fan means is
depicted as being directly attached to the housing, the fan means
may also be located more distant from the apparatus and employed
with, for example, a flexible line, to provide the desired effect.
The fan in fan housing 22 is designed to draw air in from the
chamber formed by housing 12 via vacuum air line 24. The fan draws
in air from the chamber which is laden with dust and fine particles
resulting from the cleaning operation. The air and materials in
association therewith are expelled from the fan to air exhaust duct
26. The fan is powered by a fan motor which is contained in fan
motor housing 28 which is shown as attached to fan housing 22. The
air fed to the chamber in housing 12 is desirably provided in
association with the particulate abrasive material and is
circulated in the chamber by the projecting means. Desirably, the
projecting means forces air toward the surface being treated and is
drawn upward under the influence of the fan means. The air serves
to separate fines created by the treatment of the surface from
heavier particles such as the particulate abrasive material and
larger pieces of scale or deposit which is removed from the
surface. Also, the circulation of air and its exhaust from the
blast head prevents heat buildup in the abrasive and in the various
components of the blast head assembly. The importance of this
feature is readily understood when it is realized that large
amounts of head are generated by the impact of the abrasive against
the surface to be treated. Thus, by the circulation of air it
becomes possible to operate the apparatus of the present invention
continously over relatively long periods of time with little, if
any, heat buildup in the particulate abrasive material.
If desired, the air exhausted from the blast head via exhaust duct
26 can be transmitted to a conventional dust collector (not shown)
for removal of the particulate contaminants in the air. The dust
collector can be separate from the blast head, in which case, the
communication means between exhaust duct 26 and the dust collector
is preferably flexible and allows movement of the blast head over
the surface being treated. On the other hand, the dust collector
may be affixed securely to the housing of the blast head. The
release of dust and the like from between the sealing means and the
surface being treated can, in part, be abated by operating the
apparatus so as to maintain subatmosphere pressure, i.e., a
pressure lower than ambient, in the chamber. Therefore, if any gap
occurs between the sealing means and the surface being treated by
reason of, for example, an irregularity on the surface being
treated, the atmospheric air, being at the higher pressure, will be
drawn into the chamber at the point of the gap and carrying with it
material which might otherwise escape to the surroundings.
Projection means motor housing 30 is affixed to housing 12. Also
shown in FIG. 1 is elevator motor housing 32. The elevator motor
therein powers a conveyor means which returns the discharged
particulate abrasive material to the projecting means to be reused.
A motor to propel the blast head in a horizontal direction is
provided in drive motor housing 34. The motor is used to drive
horizontal track engaging means 36. The slippage between the
horizontal track engaging means and a horizontal track means which
is engaged, is avoided through design to provide friction contact
or other essentially non-slipping contact. The horizontal track
means can be, for example, a cable, rigid or flexible track, chain
or other suitable device. One particularly advantageous means of
providing frictional contact of the engaging means 36 to, for
example, a cable is to provide a freely rotable pulley on the
opposing side of the cable from the engaging means. The freely
rotably pulley can then be drawn towards the engaging means by, for
example, a tension spring, pneumatic or hydraulic means, or other
suitable means to force the cable into contact with the engaging
means to provide the desired, frictional contact. Desirably, the
horizontal tract means is relatively flexible and positioned such
that the track means is bowed with an apex at the engaging means or
adjacent to the engaging means. When, for instance, a cable is
employed as the track means, friction suitable for traction can be
achieved be providing a pulley means which can be activated in a
direction essentially perpendicular to the surface being cleaned to
engage the cable and increase the tension in the cable. Suitable
activation means are, for instance, a pneumatic or hydraulic
cylinder. Beneficially, the pulley and the engaging means can be
cable sheaves, each with three grooves. The cable can be threaded
on the side furthest from the surface being treated of one sheave,
across to and around the second sheave and back to and around the
first sheave and across over the last groove of the second sheave.
By increasing the distance, in any desirable direction, between the
pulley and engaging means, the tension in the cable can be
increased.
Winch means 38 are provided on both sides of the housing 12 and
preferably extend perpendicularly therefrom. The winch means are
adapted for engaging a vertical support means, which can be, for
example, a flexible cable, whereby the vertical support means can
be wound on the winch means to elevate the blast head. The winch
means are preferably interconnected by a rigid shaft means and is
powered by a hoist drive means. Desirably, a hoist drive means
employed to activate the winch means is provided with a
self-braking gear drive. The vertically disposed cable can be
supported by a frame means having pulley means thereon with the
cable being attached to housing 12, passed over the pulley means on
the frame and back to winch means 38.
FIG. 2 depicts the apparatus of FIG. 1 in a front-elevational view
with a break away section to permit viewing of chamber 40 which is
enclosed by housing 12 and a further break away to permit viewing
of the supply means to supply particulate abrasive material to the
projecting means. Projecting means 42 is represented as a
centrifugal throwing wheel driven by a centrifugal throwing wheel
motor in housing 30. A drive means 44 can be employed to transmit
the power from the motor to projecting means 42. Projection means
42 can be a conventional centrifugal throwing wheel which can be
commercially obtained such as the type manufactured and sold by The
Wheelabrator Corporation and described in U.S. Pat. Nos. 2,708,814
and 2,819,562 or as the type manufactured and sold by the Pangborn
Corporation, a division of the Carborundum Company. In general, the
Wheelabrator type wheels comprise a plurality of radially extending
blades 43 arranged in circumferentially spaced apart relation
between confining disc plates. The particulate abrasive material,
which can be metallic particles, for example, steel shot, steel
grit, crushed iron, chilled iron grit, glass beads, aluminum oxide
particles, silica or the like, can be fed into the inner ends of
the blades, and the particulate abrasive material is thrown
centrifugally at high velocity from the outer ends of the blades
since the wheel is rotated at high speed about its axis, typically
at about 1,000 to 4,000 rpm. The particulate abrasive material is
thrown forward by and through opening 14 into engagement with the
surface being treated. The abrasive may contact the surface at a
slight angle to perpendicular in order to improve the cleaning
action.
The particulate abrasive material is stored in storage means 46.
Storage means 46 is provided with abrasive material transfer means
48 to supply the abrasive material to projecting means 42. As
depicted, the abrasive material transfer means is located outside
of the housing and communicates with the storage means 46 which is
depicted as in the interior of the housing. The abrasive particles
flow by gravity through abrasive material transfer means, shown as
a conduit, to a charging means 50 which is shown as a funnel having
the large opeining at the top and which is curved in a manner to
provide release of the particulate abrasive material to the center
of, for example, the centrifugal throwing wheel. Desirably, the top
of the funnel surrounds the lower end abrasive material transfer
means 48 and provides a gap sufficient to allow passage of air into
the funnel, but yet is preferably designed such that the
particulate abrasive material does not escape. The centrifugal
throwing wheel can simultaneously perform as a centrifugal air fan.
Thus, during operation, the low pressure area which exists to the
center of the throwing wheel can be employed as a motivational
force to draw in air through the gap formed at the top of the
funnel. Additionally, the presence of air being drawn into the
center of the throwing wheel assists the flow of particulate
abrasive materials into the throwing wheel. The air exhausted by
the centrifugal throwing wheel can circulate within the chamber of
the housing and desirably flow through the particulate abrasive
material after impinging upon the surface being treated so as to
wash the abrasive material and remove fine particles such as dust
and the like. The abrasive material supply means may be provided
with a valve means or motive means to control or facilitate flow of
the particulate abrasive material to the projecting means.
The particulate abrasive material, after impinging upon the surface
being treated, falls by the force of gravity to the bottom of the
chamber formed by housing 12. The spent abrasive material is picked
up by particulate abrasive conveyor means 52 to be recycled to the
projecting means 42. Conveyor means 52 is depicted as an endless
belt running in a clockwise direction on the loop around the inside
of housing 12; however, other elevator means might be used such as
pneumatic lift devices and other conventional mechanical elevators.
The endless belt may employ scoops or bucket means attached thereto
at various intervals. The drawing depicts several representative
scoops 53; however, it is realized that the scoops are spaced at
regular intervals on the entire endless belt. When operating the
scoop or bucket means is empty on the vertical downpath of the
continuous loop. As the belt passes horizontally through the lower
portion of the housing, the scoop itself can be in a vertical
collecting position. Continuing its course on the vertical up path,
the scoop or bucket means contains the abrasive material. Upon
reaching the top of the vertical up path which is preferably
located in the upper portion of the housing, the scoop or bucket
passes horizontally across the top, itself in a vertical dumping
position. The conveyor means, in this delivery zone, releases the
particulate abrasive material to the storage means. The scoops or
bucket means are preferably below the belt during the lower
horizontal pick up flight, and hence, are above the belt during the
upper horizontal dumping flight. The scoop or bucket means is
essentially free from contact which may result in friction caused
by wear. Additionally, by employing a conveyor belt having the
scoop or bucket means, less power is required for its operation
then, for example, a pneumatic elevator. The scoop or bucket means
can be designed so that a high percentage of the particulate
abrasive material, often in the neighborhood of 95 percent or more
falls into storage means 46.
The continuous belt can be a V-belt made of sturdy, flexible
material such as synthetic resins or natural rubber. The continuous
belt can contact pulleys 54 at three corners of housing 12 and
power pully 56 in the remaining corner and thus form the
configuration, of the continuous loop. Rather than a V-belt and
pulley system, the conveyor means may comprise, for example, a
chain and sprocket system wherein the pulleys are replaced by
sprockets. Power pulley 56 is depicted as engaging with conveyor
means 52 in order to move the conveyor means in a clockwise
direction. Power pulley 56 is driven by elevator motor in housing
32. The elevator motor may be attached to suitable drive means to
transmit the power to power pulley 56. An abrasive collector means
may optionally be provided in the lower portion of housing 12 to
assist the recovery of the particulate abrasive material. The
abrasive collector means may be, for instance, a hopper which is
adapted to localize the particulate abrasive material to facilitage
its pick up by the conveyor means.
The particulate abrasive material drops from conveyor means into
storage means 46. Desirably, air which is drawn from chamber 40 to
the fan means in fan housing 22 exits the chamber by a vacuum port
means which is in communication with the fan by means of vacuum air
line 24 and which is preferably located on housing 12 behind the
upper horizontal path of conveyor means 52. The air circulation in
chamber 40 can be approximately diagrammed as follows. Air enters
centrifugal throwing wheel 42 and is circulated in a direction
towards the surface being treated. The air can serve to wash the
particulate abrasive material of fine particulate matter generated
due to the action of the abrasive material on the surface. Also,
the forced air may serve to dislodge particles on the surface that
are not removed by the impact of the particulate abrasive material.
The air is then swept upward towards the inlet means carrying with
it dust and other fine particulate materials generated in the
course of the treatment of the surface. Due to the location of the
inlet means to the fan, the air passes around the conveyor means.
The proximity of the inlet means to the horizontal path of conveyor
means allows the maintenance of relatively high air velocities past
the conveyor means. These higher air velocities can beneficially be
employed to separate particles of a lower specific gravity which
are transported by the conveyor from the particulate abrasive
material. For instance, when steel shot or the like is used as the
particulate abrasive material, relatively large particles, such as
rust or paint, which are not washed from the particulate abrasive
material by the air circulated by the centrifugal wheel, may be
carried by conveyor means 52 with the steel shot to be returned to
storage means 46. The velocity of air entering the inlet means may,
however, be sufficient to remove the relatively large particles of
lower specific gravity before they enter storage means 46 and
essentially vacuum the lower density particles from chamber 40. The
laden air can be exhausted from the system via the fan and exhaust
port 26. Particles which may not be removed from the steel shot are
normally sufficiently fragile that upon being propelled by
centrifugal throwing wheel 42 and impacting upon the surface being
treated, they disintegrate to a particle size which can be readily
removed from the system.
Advantageously, storage means 46 can be provided with port 57
through which air in the chamber is drawn and thus the air can be
further directed to pass around the conveyor means to insure that
the low density particles are swept from the particulate abrasive
material. A valve means can be provided in connection with the port
means for vacuum line 24 to adjust the rate of air withdrawal from
chamber 40, and hence, the velocity of air over conveyor means 52.
An additional vacuum line may communicate from the fan means to the
housing and be adapted to sweep air from other portions of the
enclosure.
Motor housing 58 contains a hoist motor to actuate winch means 38
to provide a means of vertical movement of the blast head. The
motor is preferably attached to a drive means to power shaft 60
which is connected to winch means 38. As stated previously, the
drive means for winch means 38 is desirably self-braking.
FIG. 3 illustrates the apparatus to the present invention in
connection with a suitable rigging means for transporting the
apparatus over the surface being treated. In particular, the
surface being treated is indicated as 62 and has thereon a deposit
or scale represented by the shaded area. The blast head 10 is
positioned upon surface 62 in such a manner that the sealing means
contacts the surface to provide a relatively air tight seal. In
actual operation, the seal of the sealing means with the surface
will be broken by, for example, abrupt protusions or indentations
on the surface and thus surrounding air will be drawn into the
chamber. Casters 18 contact surface 62 and serve to position the
blast head a desired distance away from the surface so as to enable
the sealing means to properly contact the surface.
The apparatus is vertically supported by vertical support frame
means 64. Frame means 64 is depicted as comprising a plurality of
support members 66 adapted to support themselves and the blast head
when positioned at the upper edge of the surface. The frame means
can preferably run along track means 67 which is located adjacent
to the upper edge of the surface. Desirably, the track means
provides support for the frame means for vertical forces, e.g., to
counteract gravity, and for a lateral force in a direction
perpendicular and away from the surface. Caster means 68 are
provided on the frame means and contact the front of the surface
and reduce friction of movement of the frame means over the
surface. Thus, the frame means will be in equilibrium by its
contact with the track means and the front of the surface and is
adapted to move freely along the edge of the surface. Pulley means
70 are shown as affixed to the upper lateral support members of
frame means 64 and are adapted to receive vertical support means
72. The vertical support means attach to housing 12 at attachment
means 74 pass over pulley means 70 and attach to winch means 38. By
drawing more of vertical support means 72 onto winch means 38, the
blast head can move in an upwardly direction, and by releasing a
length of vertical support means 72, the blast head can be lowered.
Preferably frame supports means 64 is designed to enable passage of
the blast head at least partially into its interior. By locating
pulley means 70 to the interior of frame means 64, it is possible
to raise the blast head to a position to enable the sealing means
to reach or surpass the upper edge of the surface.
The track means which frame means 64 rides upon may be a rail or
groove in which wheel means 75, or the like, affixed to frame means
can engage. If a rail is employed, the wheel means are preferably
designed such that vertical forces and lateral forces developed by
the frame means are conteracted by contact of the wheel means and
the track means. The rail can be rigid or somewhat flexible. The
track means may be permanently secured or may be detachable.
Affixing means operable are, for example, vacuum cups, magnets,
clamps, or other fastening devices.
Attached to the surface being treated on opposing sides of the
blast head are horizontal track securing means 76. The securing
means may be permanently attached to the surface being treated or
it may be detachable. Attachment means include vacuum cups,
magnets, clamps and the like. Securing means 76 can be in the form
of a grooved track wherein the point of attachment of horizontal
track means can be quickly adjusted to the desired height, either
manually or remotely, and even automatically. Since the blast head
traverses horizontal track means, 78, it is often advantageous to
maintain about an equal the distance from the top edge of the
surface to the point at which the track means is secured to each
securing means 76. Thus, for a given vertical position of the blast
head, a horizontal pass may be made, and minimal, if any,
concurrent readjustment of the vertical position need be made. The
blast head pulls itself along the horizontal track means by
engaging means 36 which is driven by a horizontal drive motor
contained in housing 34. Normally, to affect engagement of engaging
means 36 with the track means to provide the necessary frictional
contacts, a tensioning means is provided on the blast head.
However, the tension of the track means against the engaging means
may be increased by shortening the length of track means between
the securing means. This can be done by providing, for instance, a
winch means on one of the securing means. The track means may also
be provided with a turnbuckle means for decreasing its length.
In the operation of an apparatus of the type depicted in the
drawings, the frame means 66 is at the upper edge of the surface to
be treated and above the blast head. The vertical support means 72
is attached to the blast head housing, passed over pulley means 70
and attached to winch means 38. The winch means is activated and
the blast head is elevated to the desired position. Horizontal
track means is then affixed to securing means 76 so that it is
equidistant from the top edge of the surface and contacts engaging
means 36. The horizontal drive motor can be activated to move the
blasting head horizontally across the surface. Upon starting the
projection means and conveyor means, the treatment of the surface
commences. The control of the apparatus of the present invention
can be operated remotely, thus the operator need not be closely
positioned to the blast head. After a horizontal pass, the
horizontal track means can be released from engaging means 36, and
the blast head can be raised or lowered to place it in position for
additional passes over the surface. The horizontal track means can
be repositioned to engage with the blast head and operation can
continue.
While the description of the apparatus has been in terms of travel
in a horizontal direction, it is apparent that the novel apparatus
is not limited to such horizontal operation. For example, the
opening in one side of the enclosure may have its major axis
essentially horizontal. Vertical drive can be effected by actuating
the winch means. The horizontal drive track can be replaced by a
vertical tension line passing from a point above the apparatus to a
point below the apparatus. The vertical tension line contacts a
freely rotable pulley located on the housing in a manner which
enables the tension line to force the apparatus into contact the
surface being treated.
* * * * *