Note: Descriptions are shown in the official language in which they were submitted.
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DEVICE AND METHOD FOR
EXTRACTION OF DUST FROM A GRINDER
BACKGROUND OF INVENTION
This invention relates to a machine and consumables for grinding surfaces,
such as those formed of concrete, and particularly to an improved method for
the
collection of dust and other loose material generated as part of the grinding
process.
SUMMARY OF INVENTION
A common problem that arises in grinding applications is dust or fines left on
the surface that is being ground. Conventional systems, even those with
relatively
efficient dust extraction, leave a large quantity of dust and other material
on the
ground or other surface being treated. This becomes a problem in four ways.
First, as a grinding process is being carried out, the grinding surfaces pass
over
the loose material, effectively grinding it as much as the surface being
treated. This
shortens the life of the grinding surface itself, as well as increasing the
overall time to
complete a particular job.
Second, the working surfaces of grinders are often cooled with water,
producing a dust-water mixture called slurry. Cleaning up the slurry adds time
to a
grinding operation.
Third, the dust left on the ground obscures the operator's view of the work
surface. It is difficult to achieve a consistent finish if the operator cannot
judge the
amount of material being removed.
An additional problem with typical grinding machines is that the high surface
feet-per-minute rate grinding of generates a great deal of heat through
friction that can
decrease the life of the tool.
The invention is directed to methods and arrangements for collecting dust in
machines adapted to grind surfaces that address these problems.
In one aspect of the invention, plug for a grinding machine comprises a hole
bored in the plug for use as a dust collection port.
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In another aspect of the invention, plug for a grinding machine comprises a
plurality of holes bored in the plug for use as dust collection ports.
In another aspect of the invention, a grinding machine comprises a housing; a
drive mechanism, including a shaft extending through the housing; a shroud
surrounding the shaft and abutting the housing to form a plenum; a head
connected to
the drive mechanism; at least one grinding plug having a working surface
mounted in
the head; and at least one channel extending from proximate the working
surface into
the plenum.
In another aspect of the invention, a plug-type grinding machine comprises
one or more individual shrouds for each grinding plug.
BRIEF DESCRIPTION OF DR.AWINGS
The accompanying drawings are not intended to be drawn to scale. In the
drawings, each identical or nearly identical component that is illustrated in
various
figures is represented by a like numeral. For purposes of clarity, not every
component
may be labeled in every drawing. In the drawings:
FIG. 1 is a cross-sectional view of a grinding apparatus illustrating one
embodiment of the invention;
FIG. 2A is a side view of a portion of one embodiment of a grinding apparatus
according to the invention;
FIG. 2B is an upper perspective view of the apparatus portion of Fig. 2A;
FIG. 2C is a lower perspective view of the apparatus portion of Fig. 2A;
FIG. 3A is an upper perspective view of a grinding plug according to one
aspect of the invention;
FIG. 3B is a lower perspective view of the grinding plug of Fig. 3A;
FIG. 3C is a side view of the grinding plug of Fig. 3A;
FIG. 3D is a top view of the grinding plug of Fig. 3A;
FIG. 3E is cross-section view taken along line 3E-3E;
FIG. 4A is a lower perspective view of a second grinding plug suitable for use
with the invention;
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FIG. 4B is an upper perspective view of the grinding plug of Fig. 4A;
FIG. 4C is a side view of the grinding plug of Fig. 4A;
FIG. 4D is a top view of the grinding plug of Fig. 4A;
FIG. 4E is cross-section view taken along line 4E-4E.
S FIG. 5A is a bottom view of a one embodiment of a grinding head according
to the invention;
FIG. 5B is an side view of the head of Fig. 5A;
FIG. 5C is a perspective view of the head of Fig. 5A;
FIG. 5D is a cross-section view taken along line 5D-5D;
FIG_ 6A is a bottom view of another embodiment of a grinding head according
to the invention;
FIG. 6B is a side view of the head of Fig. 6A;
FIG. 6C is a perspective view of the head of Fig. 6A;
FIG. 7A is a bottom view of another embodiment of a grinding head according
to the invention; and
FIG. 7B is a side view of the head of Fig. 7A.
DETAILED DESCRIPTION
This invention is not limited in its application to the details of
construction and
the arrangement of components set forth in the following description or
illustrated in
the drawings. The invention is capable of other embodiments and of being
practiced
or of being carried out in various ways. Also, the phraseology and terminology
used
herein is for the purpose of description and should not be regarded as
limiting. The
use of "including," "comprising," "having," "containing," "involving," and
variations
thereof is meant to encompass the items listed thereafter and equivalents
thereof, as
well as additional items.
Referring to Fig. 1, an exemplar floor grinding machine 1 suitable for use
with
the invention includes a frame 100, a housing 200, and a grind assembly 400.
Suitable grinding machines for use with the invention include, but are not
limited to,
the Blastrac BMG 2500 Plug Style Grinder. Note that "grinding" is defined
herein
to encompass all operations that concern the surfacing of hard materials, such
as
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concrete, stone, terrazzo, and the like, including the processes commonly
known as
grinding, sanding, polishing, and bufFing.
In this embodiment, the frame 100 is connected to a drive mechanism
including wheels (not shown) and a handle assembly with controls (also not
shown),
as is conventional in the art. A dust collection system (not shown), including
a dust
collection bin or bag, may be mounted in or on the housing, or may be separate
from
the floor grinding machine 1.
In the exemplar embodiment, the frame 100 is connected to the housing 200
that supports a motor (not shown) for driving the grind assembly 400 via shaft
150.
The housing 200, constructed of sheet steel or other durable material,
includes a top
portion 202 as well as peripheral wall portions 204 that extend to the floor
or other
surface to be ground. The wall portions may include seals 206 where they meet
the
surface to be ground. The seals, when used, may be rubber or plastic gaskets,
nylon
bristles, metal shrouds, or any other suitable material or structure, as would
be
understood by one of skill in the art.
The shaft 150 projects through the housing 200 and drives one or more heads
240 in a rotating fashion. In some embodiments, a coupling mechanism 270, such
as
a Morflex coupler, may be positioned between the shaft 150 and the one or
more
heads 240. In one embodiment, the grinding machine 1 includes two heads 240.
In this exemplar embodiment, each head 240 includes at least one bore 245 for
receiving a wear plug 300. In some embodiments, the bores 245 are tapered, so
that
the wear plugs 300 may be held in place by a friction fit, aided by the weight
of the
machine. In one embodiment, each head 240 includes three bores 245 for
receiving
three wear plugs 300.
The wear plugs 300 of this embodiment may be made of any appropriate
materials or materials. One suitable plug is the Blastrac X Type Diamond
Plug.
This plug has an X-shaped extension with a course grit diamond coating. A
Blastrac(@
X Type Diamond Plug modified for use with one embodiment of the invention is
illustrated on Figs. 3A-3E. Another suitable plug would be the Blastrac 30-40
Grit
Diamond Plug, shown, as modified for use with one embodiment of the invention,
in
Figs. 4A-4E. It should be understood that the abrasive used in conjunction
with this
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invention also may be formed of or comprise any appropriate material or
materials
other than diamond, and that it may be of any suitable grit.
It should be understood that other wear plugs may be suitable for use with the
invention, as would other types of consumables, including discs or wheels, as
would
be understood by one of skill in the art.
In the exemplar embodiment, the wear plugs 300 are generally cylindrical and
are tapered along at least part of their length, so as to facilitate the
friction fit into
bores 245. In other embodiments, the wear plugs 300 may be shapes other than
cylinders and may or may not be tapered. Other methods of securing the wear
plugs
300 into the bores 245 may also be used, including threads, clips, pins,
bolts, or any
other appropriate method.
In some embodiments, the wear plugs 300 are attached to the floor grinding
machine 1 by other means, such as by surface mounting and fixation to the head
240
by means of the bolt or other threaded element, or otherwise. The method of
connecting the wear plugs to the machine is not material to the invention.
The wear plugs 300 include a working surface 305; commonly coated with a
thickness of diamond grit or another abrasive, and one or more channels 310.
By
"working surface" it is meant the portion of the plug that performs the
grinding
operation. In the case of the Blastrac X Type Diamond Plug, for example, the
working surface would include the face of the "X," indicated by reference
numeral
305 in Figs. 3A-3E. In this and other embodiments, the working surface 305
need not
be flat, and may instead be convex, concave, or undulating. In some
embodiments,
the working surface 305 may have rounded or chamfered edges.
In one embodiment of the invention, the wear plugs 300 include one channel
310 in the center of the wear plug 300, along its axis. In other embodiments,
there
may be, in addition to or instead of a center channel, a plurality of channels
310
spaced around the axis of the wear plug 300, either regularly or irregularly.
In the illustrated embodiment, the channels 310 are cylindrical bores that are
approximately 3/8 of an inch in diameter, although other cross-sectional
shapes and
sizes could be appropriate. Other embodiments may employ a larger number of
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channels of the same, a smaller, or a larger cross-sectional area. In some
cases,
channels 310 may be of one or more different diameters.
Where the channels 310 are spaced about the axis, they may run in a direction
parallel to the axis of the plug, or some or all may taper in the direction
of, or away
from, the axis.
The channels 310 may be arranged such that they all exit the wear plugs 300
and the same radial distance from the axis, or, in other embodiments, the
channels 310
may exit the wear plugs 300 at different radial positions relative to the axis
of the
wear plug 300. In some embodiments, the channels 310 may exit the plug through
the
1 o working surface 300; in others, they may exit the plug a position
proximate to, but not
on, the working surface 300.
In the illustrative embodiment, the wear plug 300 also includes a recess 320
in
the end opposite the working surface 305. The recess 320 may be sized and
positioned such that each channel 310 opens into recess 320, forming a small
plenum,
rather than extending to the top of the plug.
In some embodiments, the inventive system includes individual plug shrouds
330 enclosing the portion of each wear plug 300 that protrudes below the head
240.
The plug shrouds 330 may be made of a flexible material, such as urethane, and
may
be held in place by friction and/or by a taper on the wear plugs 300. In some
embodiments, the plug shrouds 330 are sized to have the same axial length as
the
portion of the wear plug 300 extending below the head 240. As the wear plugs
300
are worn, the plug shrouds 330 also wear, so that shrouds 330 always extend to
the
working surface.
In some embodiments, the plug shrouds 330 may include one or more reliefs
(not shown) formed on the inside (i.e., the side in contact with the wear plug
330) to
facilitate the flow of air and/or reduce clogging.
On the upper surface of the head. 240 of this embodiment there are projecting
tubular cuffs 250 that are positioned to correspond to the location of each
wear plug
300. In the illustrative embodiment, the cuffs 250 are terminated in a plane
such that
the radial outermost portion extends further above the top side of the head
240 than
the radial innermost portion. The cuffs 250 each receive a hose 260 made of an
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abrasive resistant material. The hoses 260 may be sized for a friction fit
over the cuffs
250 and/or may be secured with a clamp or by other means.
. The other end of each hose 260 is connected to an inverted shroud 210. The
inverted shroud 210 is bowl-shaped and surrounds the shaft 150. The bottom of
the
shroud 210 is connected to the shaft 150, directly or indirectly, such that it
rotates
with the shaft 150. The shroud 210 is flexible and is also constructed of an
abrasive
resistant material. The lip 215 of the shroud rests against, but is not
connected to, the
lower surface of the top 202 of the housing 200.
Extending through the top 202 of the housing 200 is at least one dust
evacuation port 280. The port 280 is positioned such that it communicates with
the
plenum formed by the shroud 210 and the top of the housing 202. The port 280
may
be perpendicular to the top of the housing or, as in the illustrative
embodiment,
arranged with its axis at an angle relative to the top 202 of the housing 200.
An evacuation hose (not shown) connects the port 280 to a dust collector (also
not shown).
In operation, the dust collector draws air and entrained dust and fines
through
the channel(s) 310 in each plug, through the recess 320 in each plug, through
the cuffs
250 on the head 240, through each hose 260, and into the plenum formed by the
shroud 210 and the top 202 of the housing 200. The air, dust, and fines are
then
drawn through the port 280 and into the dust collector.
There are at least four benefits of the inventive system of this invention.
First, dust is removed much more effectively than previous methods. Second,
with
more effective dust removal, the grinding tool itself is able to operate more
efficiently.
Third, the focused flow of air through the plugs cools the wear plugs 300,
including
any diamond or other material forming the working surface 305, and prolongs
the life
of the plug. Fourth, the material is removed more efficiently from the surface
being
treated, allowing the operator a better view of the progress being made.
The holes in the grinding tooling, in effect, become high velocity ports in
close proximity to the development of dust. The ports travel with the plug,
immediately capturing airborne dust as well as dust falling back to the
surface. As a
result, only a minimal amount of dust falls to the surface between plugs,
allowing
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each successive plug can more efficiently engage the work surface. The system
also
allows air to flow through the tool, dissipating heat and avoiding clean-up
associated
with water-cooling of the wear plugs or working surface.
Another embodiment of the invention is illustrated in Figs. 5A-D. In this
arrangement, a head 500 carries three wear solid wear plugs 510, which may be
mounted by any suitable method. Optional shrouds 520 are positioned about the
solid
wear plug 510. One or more local dust evacuation ports 530 extend through the
circular head 500 and communicate with a gap between the solid wear plugs 510
and
the shrouds 520. This embodiment provides localized high velocity ports that
travel
with each solid wear plug 510, without the need for channels extending though
the
plugs themselves.
Figs. 6A-C depict another embodiment of the invention. In this arrangement,
a head 600 carries three solid wear plugs 610, mounted, as above, in any
appropriate
manner. Positioned behind each wear plug 610, relative to the direction of
travel of
the rotating head 600, are elongated evacuation ports 630. The elongated
evacuation
ports 630 extend through the head 600 and to the surface being treated. The
elongated
evacuation ports 630, which may be made of any appropriate rigid or semi-rigid
material and have a cross-section that is rectangular or any other suitable
shape, wear
as the plugs 610 wear and provide localized high-velocity dust collection.
Figs. 7A-B show a head 700 that includes a plurality of wear plugs 710.
Positioned behind each wear plug 710, relative to the direction of travel of
the rotating
head 700, are elongated agitators 720. The agitators, which may be made of
bristles,
urethane, neoprene, or any other appropriate rigid or semi-rigid material,
operate to
stir up dust or other debris from the surface of being treated to allow it to
be entrained
in the flow of air to a dust collection system. Elongated agitators 720 may be
used in
a system with conventional dust collection, or in conjunction with one or more
of the
localized, high velocity systems described above.
Having thus described several aspects of at least one embodiment of this
invention, it is to be appreciated various alterations, modifications, and
improvements
will readily occur to those skilled in the art. Such alterations,
modifications, and
improvements are intended to be part of this disclosure, and are intended to
be within
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the spirit and scope of the invefntion. Accordingly, the foregoing description
and
drawings are by way of example only.
