Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
PRESSURE-FIT GRINDING PAD ASSEMBLY AND METHOD OF CONSTRUCTION
FIELD OF THE INVENTION
The present invention relates to grinding machines and more particularly to
grinding
disc constructions and grinding pads adapted to be removably connected to the
grinding
disc of such machines for grinding concrete surfaces or like hard surfaces to
form a
smooth surface.
BACKGROUND OF THE INVENTION
Grinding machines of many type of construction are known wherein abrasive pads
are secured to one or more motor driven grinding disc to abrade and polish
hard
surfaces such as concrete surfaces, stone surfaces such as granite, marble,
ceramic or
any hard surface material where a smooth surface finish or polish finish is
required.
These abrasive pads contain abrasive particles such as diamond, silicon
carbide and
other wear resistant particles which are bonded in a carrier such as by
sintered bond,
electroplate bond, vacuum brazed, epoxy and resin materials and other such
suitable
hard bonding materials.
In one known abrasive pad construction these abrasive pads are formed in many
shapes and these pads are braised onto an outer surface of a wedge-shaped
steel
support of sufficient thickness to form a strong bond with the pads. These
supports are
removably connected to a motor driven grinding disc and firmly held in place
by
wedging and the centrifugal force provided by the rotational speed of the
disc. There
are usually two of such abrasive pads braised to a steel mounting base support
in close
proximity to one another. Because the braising operation is time consuming,
usually
taking about five minutes or more to braise two of such pad on a base, and
somewhat
delicate due to the small size of the pads and their close proximity to one
another, such
operation as proven costly. The operation consists of securing the steel base
in a vise
with flux material applied over the top surface of the base. The worker then
has to
place braising material, herein small silver strips, at precise positions on
the base and
then dispose the abrasion pads over the braising material. The steel base is
then
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heated with a torch from underneath until the base and pads becomes red hot
and
reaches a temperature sufficient to melt the braising material and at which
point the
operator must carefully re-align the pads in position on the melted silver.
The steel
base then has to cool and the flux material removed from the surface of the
base.
One disadvantage of this braising process is that the intense heat applied to
the
abrasive pads reduces the life of the pads for the reason that the hard
abrasive chips,
such as diamond chips, become graphitized causing the external surface of the
pads to
break up faster when in use with the weight of the machine resting thereon.
Also if the
assembly is not properly made such as improper amount of braising material
being
applied, there is the risk that the pad could distort or disconnect during a
floor grinding
operation particularly if the floor surface has different hardness and non-
smooth areas.
Another disadvantage is the shape of the pad, for example rectangular or wedge
shape,
which can render the braising operation more difficult and time consuming.
Accordingly, such pad construction is costly and prone to failure if not
properly
constructed. Further, re-cycling the base is not practical and too time
consuming due to
the fact that metal fragments remain on the top surface of the base requiring
grinding.
There is therefore a need to overcome such grinding pad assembly problems by
providing a fabrication method which is less time consuming and not dependent
on a
braising process for connecting grinding pads to an attachment base or disc.
There is
also a need to provide a grinding pad assembly wherein pads can have different
shapes
of abrading heads and mounted on a common support base and further wherein a
single motor driven support disc can be fabricated to receive desired numbers
of
grinding pad assemblies and permit different pad configurations on the
grinding disc.
There is also a need to provide grinding pads which are quickly replaceable by
a user
person without the need to purchase pads assembled to a support base. A
further need
is to provide grinding pad assemblies which overcome substantially all of the
disadvantages of the above mentioned prior art.
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SUMMARY OF THE INVENTION
It is a feature of the present invention to provide a pressure-fit grinding
pad assembly
which substantially overcomes the above mentioned disadvantages of a known pad
construction and provide for the desired needs mentioned herein above.
Another feature of the present invention is to provide a pressure-fit grinding
pad
assembly wherein the grinding pad is immovably secured to an attachment base
by a
press to prevent removal or accidental disconnection of the pad and wherein
disconnection of its attachment base is made only by the application of a
suitable
pressure punching force.
A further feature of the present invention is to provide a pressure-fit
grinding pad for
removable securement in selected ones of holes provided in a high speed
rotatable
grinding disc of a floor grinding machine.
A still further feature of the present invention is to provide a grinding pad
assembly
which is removably secured in selected ones of a plurality of cavities formed
about a
circumferential axis of a grinding disc and held secured therein by friction
and the
centrifugal force of the grinding disc when rotatably driven.
Another feature of the present invention is to provide a method of
constructing a
grinding head of a floor grinding disc assembly which overcomes the above
mentioned
disadvantages and which does not use a braising method.
A further feature of the present invention is to provide a novel grinding pad
wherein
the mounting base of the abrasion head is formed as to provide removable
engagement
into attachment means of a grinding disc.
According to the above features, from a broad aspect, the present invention
provides
a pressure-fit grinding pad assembly which is comprised of a mounting base
having one
or more through bores extending from a top surface of the mounting base to a
bottom
surface thereof. The through bores each have an inner surface of defined cross-
sectional shape extending between the top surface to the bottom surface. A
grinding
pad is formed by an abrasion head of abrasion material immovably bonded on a
metal
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attachment base also having a defined cross-sectional shape dimensioned for
pressure
fit connection into the the inner surface of the mounting base by the use of a
press
exerting a pressure sufficient to fully engage the attachment metal base in
the through
bore to prevent removal of the attachment base from its securement therein
without the
use of pressure punching the attachment base from the through bore. The
abrasion
head also projects above the top surface of the mounting base.
According to another broad aspect of the invention there is provided a
pressure-fit
grinding pad for removable securement in a high speed rotatable grinding disc
of a floor
grinding machine. It comprises a circular grinding disc having a plurality of
through
bores extending from a top surface of the grinding disc to a bottom surface
thereof.
Each of the through bores has a common inner cross-sectional surface disposed
between the top surface to the bottom surface of the grinding disc. A grinding
pad is
formed by an abrasion head of abrasion material immovably bonded on a metal
attachment base having a defined cross-sectional shape dimensioned for
pressure fit
connection in selected ones of the through bores by the use of a press. The
press
exerts a pressure sufficient to fully engage the attachment metal base in the
through
bore to prevent removal of the attachment base from its securement therein
without the
use of pressure punching the attachment base from the through bore. The
abrasion
head projects above the top surface of the grinding disc.
According to a still further broad aspect of the present invention there is
provided a
pressure-fit grinding pad assembly for removable securement to a high speed
rotatable
grinding disc. The grinding pad assembly comprises an abrasion head bonded
onto a
mounting base. The disc is a circular flat grinding disc having a plurality of
grinding pad
engaging cavities formed in an outer surface thereof and disposed spaced apart
along a
circumferential axis of the grinding disc. The grinding pad engaging cavity is
in the form
of an open top end cavity having a grinding pad receiving end section and a
grinding
pad engaging section for receiving the mounting base of the grinding pad in
engagement therein and with the grinding pad abrasion head projecting above
the outer
surface of the grinding disc.
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According to another broad aspect of the present invention there is provided a
grinding pad comprised of an abrasion head section of abrasion material
immovably
mounted onto a metal mounting base section. The mounting base section has at
least
sections thereof provided with connecting formations shaped to define
engagement
means for securing the grinding pad in attachment means of a motor driven
grinding
disc of a floor grinding machine.
According to another broad aspect of the invention there is also provided a
method
of constructing a grinding disc for use with a floor grinding machine. The
method
comprises the steps of:
i) forming a grinding pad by immovably bonding an abrasion head formed of
abrasion
material to a metal attachment base, and
ii) pressure-fit connecting the metal attachment base to coupling means
associated
with the grinding disc, and wherein the pressure fit is performed by the use
of sufficient
pressure to prevent removal of the attachment base from the coupling means
without
the use of pressure punching the attachment base from the coupling means.
In the method, the coupling means is a metal mounting base, and wherein the
step
(i) of forming the grinding pad comprises boring one or more through bores of
predetermined cross-section in the metal mounting base. The mounting base
bottom
surface is a flat bottom surface. The step (ii) comprises pressure fit
connecting the
metal attachment base of the grinding pad in one of the said one or more
through bores
with the abrasion head projecting above the top surface of the mounting base
by the
use of the press exerting sufficient pressure to prevent removal of the metal
attachment
base without the use of pressure punching the metal attachment base from the
through
bore.
Also in the method, the coupling means is constituted by a plurality of
grinding pad
engaging cavities formed in an outer surface of a single flat grinding disc
and disposed
spaced apart along a circumferential axis of the flat grinding disc. The
grinding pad
engaging cavity is an open-top-end cavity having a grinding pad receiving end
section
and a grinding pad engaging section. The step (ii) comprises positioning the
metal
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attachment base of the grinding pad in the grinding pad receiving end section
and
displacing the metal attachment base into the grinding pad engaging section
for
connecting the grinding pad to the flat grinding disc with the abrasion head
projecting
above the outer surface of the flat grinding disc.
Still further in the method each of the retention means is a mounting base
engaging
cavity defining a mounting base receiving end section and a mounting base
engaging
section of wedge-shaped configuration defining opposed inwardly tapered side
walls.
The step (ii) is comprised by positioning the metal mounting base of the
grinding pad
assembly in the mounting base receiving end section with the attachment means
aligned with the mounting base engaging section and displacing the grinding
pad
assembly to cause the sloping opposed side surfaces of the metal mounting base
to
wedge under the opposed inwardly tapered side walls of the mounting base
engaging
section of the mounting base engaging cavity.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention will now be described with
reference to examples thereof as illustrated in the accompanying drawings in
which:
Figure 1 is a perspective view of a typical type of floor grinding machine
capable of
being fitted with grinding discs equipped with pressure-fit grinding pads of
the present
invention;
Figure 2 is a bottom view of the floor grinding machine of Figure 1 showing
three
grinding discs equipped with the pressure-fit grinding pad assemblies of the
present
invention;
Figure 3 is a perspective view of a grinding pad assembly constructed in
accordance
with the prior art and wherein the grinding pads in disc form are braised on
the top
surface of a steel attachment wedge-shaped base;
Figure 4A is a perspective view of the construction of the grinding pad used
in the
grinding pad assembly of the present invention and wherein the pad is formed
with an
abrasion head bonded to a steel attachment base;
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Figure 4B is a side view of Figure 4A;
Figure 5 is a top view of the wedge shaped metal mounting base constructed to
receive pressure-fit grinding pads of the invention and illustrating, in an
exaggerated
form, the tapered through bores formed in the mounting base;
Figure 6 is a cross-sectional view of the grinding pad assembly and wherein
the
grinding pad is shown press fitted into the metal mounting base and wherein
there are
no braising material deposits deposit formed about the grinding pad;
Figure 7 is a perspective view of the assembled pressure fit grinding pad
assembly
constructed in accordance with an embodiment of the present invention;
Figure 8A is a perspective view of a grinding disc showing the grinding pad
assembly, of Figure 7, and illustrating how the pressure fit grinding pad
assembly is
secured to the disc;
Figure 8B is a perspective view similar to Figure 8A showing all three
grinding pad
assemblies at a secured position;
Figure 9A is a perspective view of another embodiment wherein a single motor
driven support disc assembly is provided and wherein a detachable grinding
disc is
formed with a plurality of engaging cavities for receiving in pressure-fit, in
selected ones
of the cavities, the grinding pad of figures 4A and 4B, and as herein
illustrated, the
grinding disc is shown detached from its support disc to permit it to be used
in a press
to immovable pressure fit grinding pads in selected ones of the cavities;
Figure 9B is a perspective view of the support disc assembly of Figure 9A with
grinding pads of the present invention shown pressure-fit connected in two
circumferential rows of engaging cavities
Figure 10 is a fragmented side view showing the construction of the detachable
grinding disc;
Figure 11 is a fragmented view showing the basic parts of the motor driven
detachable disc assembly;
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Figure 12A is a perspective view of another embodiment of the construction of
the
grinding pad and wherein the metal attachment base has a different
configuration than
the one illustrated in Figure 8A and 8B;
Figures 12B to 12D are top, front and rear views respectively of the grinding
pad
illustrated in Figure 12A;
Figure 13A is a perspective view of a still further embodiment of a single
large
grinding disc in which is formed a plurality of open-top-end engaging cavities
for
receiving in sliding friction fit the grinding pad as illustrated in Figure
12A and wherein a
plurality of the grinding pads are shown in their loaded position prior to be
engaged at
their engaged position;
Figure 13B is a perspective view similar to Figure 13A showing the grinding
pads at
their engaged position in the cavities;
Figure 14A is a perspective view of another type of grinding machine, herein a
hand-
held type grinder, capable of being fitted with small grinding discs equipped
with
pressure-fit grinding pads of the present invention;
Figure 14B is a top view of the grinding disc illustrating the grinding pad
assembly
using the combination of modified retainers of Figure 8A, herein formed in the
top
surface of the disc, for use with the grinding pads of Figures 12A to 12D;
Figure 14C is a cross-sectional view illustrating a grinding pad secured
between the
clamping ridges formed and projecting from the outer surface of the grinding
disc;
Figure 15A is an exploded perspective view of the press component assembly for
forming a plurality of grinding pad assemblies as illustrated in Figure 7 and
in a single
press stroke operation, and
Figure 15B is a side view showing the press component assembly in an assembled
condition prior to be placed in a press for engaging the grinding pads in
their respective
mounting base.
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DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, and more particularly to Figures 1 and 2, there
is
shown generally at 10 a typical floor grinding machine which is comprised of a
grinding
head assembly 11 which is displaced by a framework 12 mounted on a wheel
assembly
13. A pair of handles 14 is connected to the framework for a user person to
displace
the grinding head assembly 11 over a floor surface constructed of concrete,
stone or
other such hard materials. The head assembly is provided with an annular
protective
skirt 17 to permit, by the use of a vacuum, the removal of dust particles
which can
cause nausea to the user person when grinding concrete surfaces. The head
assembly
11 has a motor 14 mounted thereon to impart rotation to one or more grinding
discs,
herein three grinding discs 15, by drive coupling means, not shown but obvious
to a
person skilled in the art. Such drive coupling means may consist of various
linkage
arrangements which do not form part of the present invention. The motor and
drive
linkages constituting the head assembly provides weight onto the grinding
discs 15.
Has shown in Figure 2, the grinding discs are equipped with press-fit grinding
pad
assemblies 16 constructed in accordance with one example of the present
invention.
Referring to Figure 3 there is shown a grinding pad assembly 18 constructed in
accordance with the prior art and wherein two grinding pads 19, herein in the
form of a
circular discs but they could have any suitable form, are braised directly on
a flat top
surface 20 of a wedge-shaped steel plate which forms a mounting base 21. Has
herein
shown, braising silver material 22 is use to heat braise the grinding pads 19
to the
mounting base 21 and silver deposits can be seen fused about the base of the
pads 19.
The mounting base is machined to form connecting flanges 24 on opposed sides
thereof for retention engagement between the retainer plates 23 secured to the
outer
face of the grinding discs 15. The many disadvantages of such grinding pad
assembly
18 has been described herein above.
The present invention overcomes the problems of the prior art grinding pad
assembly 18 of Figure 3 as illustrated by Figures 4A to 7. As shown in Figures
4A and
4B, the grinding pad 25 of the present invention is formed in two parts,
namely an
abrasion head 26 of abrasion material which is bonded on a metal attachment
base 27.
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The abrasion head 26 is herein shown as a circular disc but it may have other
forms
such as rectangular shape, wedge shape, diamond shape, etc. bonded on top of
the
attachment base 27. The abrasion head can also have abrasion material of a
specific
grit count as desired for grinding different hard surface materials. The
attachment base
27 is herein shown as having a circular cross-section but it can also have a
different
cross-sectional shape for reasons as will be described herein. As shown the
attachment base 27 is also formed with a slight inward conical taper 27' for
ease of
connection in holes or bores formed in the mounting base 280f Figure 7.
As shown in Figures 5 to 7, the mounting base 28 is constructed similar to the
base
21 of Figure 3, with the exception that two through bores 29 are formed in the
steel
base to receive in pressure-fit therein the attachment base 27 of the grinding
pad 25.
The through bores 29 extend from a flat top surface 31 to a flat bottom
surface 32 of the
mounting base 28 Also, the mounting base is of wedge shape, similar to Figure
3, and
formed with connecting flanges 33 and these constitutes attachment means. The
through bores 29 can also be formed with a complimentary tapered inner surface
29', in
the range of 5 to 10 degrees, complimentary to the conical shaped of the
attachment
base 27 of the pad, to facilitate the press-fit assembly of the pad therein.
It is pointed
out that to secure the grinding pads 25 into the through bores 29, the
mounting base 28
of the pads 25 positioned over their respective bores, and disposed on a press
which is
capable of exerting a pressure of about 250 psi or more and the press is
actuated to
press the pads into the through bores as illustrated by Figure 6. Accordingly,
this
pressure-fit engagement prevents the pads from being accidently dislodged
during use
but more importantly reduces manufacturing costs, is less hazardous to
fabricate, and
not prone to errors in its assembly. Also, after the abrasion head 26 is worn
out
replacement pads can be secured in the mounting base 28 by the use of pressure
punching the attachment base 27 from its press fit connection in the through
bore 29
and installing new grinding pads 25 by the use of a press.
It is to be noted that several mounting bases 28 with pads 25 positioned
thereon can
be press fitted at the same time in a single operation. Such technique greatly
reduces
assembly time as compared to the assembly of the prior art, as shown in Figure
3,
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grinding pad assembly 18 of the prior art wherein each grinding pad assembly
is
individually manufactured by a time consuming process and subjected to errors
in its
fabrication. Further, with the present invention, a user person of the floor
grinding
machine can attend to the replacement of grinding pads from the grinding discs
of its
floor grinding machine resulting in a cost saving to the user person by not
having to
purchase pad assemblies.
Figure 7 illustrates the assembled pressure fit grinding pad assembly 30
constructed
in accordance with Figures 4A to 6 and Figures 8A and 8B illustrates how these
pad
assemblies are secured to the grinding discs 15 of the floor grinding machine
10
illustrated in Figures 1 and 2. The retainer plates 23 are secured spaced-
apart on the
flat top surface 34 of the grinding disc 15 and define between spaced side
edges
thereof open top end wedge shaped cavities 35 to receive in friction fit
therein the
mounting bases 28 of the grinding pad assembly 30. Their side edges are also
formed
with a top projecting flange 36 to project in friction fit over the connecting
flanges 33 of
the mounting base 28. As shown in Figure 8A, two grinding pad assemblies 30
are
shown in secured position while the pad assembly 30' is shown at a position
prior to
being inserted into the vacant open top end cavity 35. The connecting flanges
33 have
wedge shaped straight side surfaces 33' for friction fit engagement with the
side walls of
the cavities 35 for frictional engagement therein. Also, during use, the
centrifugal force
generated by the high speed rotation of the disc 15 maintains the grinding pad
assemblies 30 firmly engaged in their respective open top end cavities 35, as
shown in
Figure 8B.
With reference now to Figures 9A to 11, there is illustrated another example
of the
construction of the pressure-fit grinding pad assembly wherein the grinding
pad 25 of
Figures 4A and 4B is secured in a mounting base which is herein constituted by
a
grinding disc 40 which is provided with a plurality of through bores 41
extending from a
top surface 42 thereof to a bottom surface 43. Each bore 41 is formed with a
common
inner cross sectional surface dimensioned to receive the attachment base 27 of
the
grinding pad 25 in friction fit therein by the use of a press exerting a
pressure as
mentioned herein above to firmly engage the pad and permit removal of the
attachment
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base of the pad only by the use of a punching pressure with sufficient force
to detach
the base from the disc 40. The through bores 41 may have a slight conical
taper as well
as the attachment base to facilitate mating the attachment base with a
selected one of
the through bores 41, as described above with respect to the other embodiment.
As
herein illustrated, through bores 41 are formed along two circumferential
paths of the
grinding disc 40 adjacent the outer edge 44 thereof. Figure 9B shows grinding
pads 25
secured in all through bores 41 of the disc 40. In practice a floor grinding
machine
operator will secure or have secured grinding pads in selected ones only of
the through
bores. The operator may also mount grinding pads having different abrasion
head
shapes or may equip a few of the grinding discs 40 with grinding pads having
different
grit counts, for example 16 grit or 20 grit, for quick interchange, depending
on the
surface to grind.
The grinding disc 40 is also provided with connectors projecting from the
bottom
surface 43 for quick connection under the head assembly 11, herein provided by
two
spaced-apart connector pins 45. The connector pins 45 are formed with an
engaging
head which is configured for clamping engagement by spring connectors 46
secured in
matting holes 55 of a support disc 47. The support disc 47 has a circumference
substantially the same as that of the circular grinding disc 40. The support
disc 47 is
coupled to a rotatable drive platform 49 through a flexible connecting
assembly 48
whereby the grinding disc 40 and its grinding pads 25 can pivot over floor
surface
irregularities. Such is well known in the art. A spacing stabilizing support
plate 50 or
formation is provided on the top face 51 of the support disc 47 to abut the
bottom
surface 43 of the grinding disc 40 to retain the grinding disc 40 parallel to
the support
disc 47 to prevent the transfer of shearing forces forces to the connector
pins 45 cause
by any unstable and shaky movement of the grinding disc 40 during rotational
drive
thereof by the motor of the floor grinding machine. The holes 52 in the
central area of
the grinding disc 40 permits access to fasteners there under and not shown.
With reference now to Figures 12A to 13B there will be described a still
further
example of the pressure-fit grinding pad assembly of the present invention for
removal
securement in a high speed rotatable grinding disc 60, as illustrated in
Figures 13A and
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136. With this particular embodiment, the grinding pad 25' has a different
construction
in that its mounting base 61 is formed with connecting formations which, as
herein
shown with a circular shaped head 63, projects outwardly from the
circumference of the
abrasion head 63 to define engagement means for securing the grinding pad 25'
in
attachment means constituted by grinding pad engaging cavities 64 formed in an
outer
surface 65 of the grinding disc 60.
The grinding pad 25' mounting base 61 is formed with tapered side walls 65 and
as
shown in Figure 126 two of the opposed sidewalls, namely side walls 65'
converge in a
common direction to form a wedge shaped mounting base 61. The side walls 65'
also
slope outwardly downwards. The front and rear side walls 65" and 65" are
straight side
walls. The bottom surface 66 is a flat bottom surface for sliding engagement
on a flat
bottom wall 67 of the cavities 64. Although the abrasion head 63 is herein
shown as a
circular disc shape head, it can have other shapes as mentioned herein above.
With reference to Figures 13A and 13B, it can be seen that grinding pad
engaging
cavities 64 are open-top-end cavities disposed equidistantly spaced all along
a
circumferential outer surface of the grinding disc 60. Each cavity 64 define a
grinding
pad receiving end section 68 for receiving the mounting base 61 of the
grinding pad 25'
therein. The cavities 64 have a depth substantially equal to the thickness of
the
mounting base 61 of the grinding pad 25'whereby the grinding pad abrasion head
63
projects above the outer surface 69 of the grinding disc 60. The cavities 64
also define
a grinding pad engaging section 70. These grinding pad engaging sections 70
are
formed with tapering side walls 71 to define a wedging section complimentary
to the
wedge shape mounting base 61 of the grinding pad 25'. These side wall 71 also
taper
inwards from the outer surface 69 of the grinding disc 60 to the flat bottom
wall 67 of the
cavities 64 and at a sloping angle which is the same as that of the opposed
side walls
65' of the wedge shaped mounting base 61 of the grinding pad 25'.
The grinding pad 25' is engaged within the cavities 64 by simply inserting the
mounting base 61 of the grinding pad 25' into the grinding pad receiving end
section 68
of the cavity 64 which is larger than the circumference shape of the mounting
base 61
and to slide the grinding pad 25' into the grinding pad engaging section 70
until the
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opposed wedge shaped side walls 65' of the mounting base are in frictional
engagement with the undercut wedging tapered side walls 71 of the grinding pad
engaging section 70. There is sufficient frictional engagement of the grinding
pads 25'
within the cavity engaging sections 70 to permit manipulation of the grinding
disc 60 to
be installed under the head assembly 11 of the floor grinding machine 10. Of
course,
during use of the machine when the grinding disc 60 is placed into rotation
and the
centrifugal force produced by the rotating grinding disc will apply a pushing
force on the
grinding pads 25' to wedge the grinding pads 25' firmly within their grinding
pad
engaging sections 70 of the cavities. Although, Figures 13A and 13B illustrate
grinding
pads installed in all of the cavities 64, there may be less grinding pads
equidistantly
mounted in only selected ones of the cavities.
Referring now to Figure 14A there is shown another type of grinding machine,
herein
a hand-held grinder 90 in which there is housed an electric motor and gearing
to impart
rotation to a small grinding disc 91. As shown in Figures 14B and 14C, the
disc 91 is
provided with grinding pad engaging means in the form of pairs of clamping
ridges 92
which are formed in the outer surface 93 of the disc 91 by a machining
process. Each
pair of clamping ridges 92 is comprised by spaced apart ridge formations 92'
which are
spaced apart a predetermined distance and shaped to define there between a
wedge
shape opening 94 with opposed side walls 95 of the pair of clamping ridges 92'
being
inwardly inclined as shown in Figure 14C to receive in frictional pressure-fit
there
between the tapered and sloping side walls 65' of the grinding pad 25' as
illustrated in
Figures 12A-12D. These pads 25' are pressed into the wedge shape opening with
sufficient force when assembling the disc 91with grinding pads 25' and during
use, the
pads are maintained forceably between their pair of clamping ridges 92 by the
centrifugal force developed by the rotating disc 91. To remove the grinding
pads 25'
after their abrasion head 63 is worn, it is necessary to punch out the
mounting base 61
by applying a sufficient punching force of atleast 250 psi in the direction of
arrow 96 as
shown in Figure 14B.. Has herein shown, there are pairs of clamping ridges 92
spaced-
apart along an outer circumferential axis of the disc and also about an inner
circular
concentric axis.
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The examples of the preferred embodiment described herein above provide a
simple
method of constructing a grinding disc for use in a floor grinding machine or
hand-held
grinder and which can be briefly summarized as follows. A grinding pad is
formed by
immovably bonding, by suitable means such as braising, an abrasion head of
abrasion
material to a metal attachment base which as described herein is a steel base.
The so
form grinding pad is then pressure fit connected to a metal attachment base by
a
coupling means associated with the grinding disc. The pressure-fit connection
is
performed in a press exerting sufficient pressure to prevent ease of removal
of the
attachment base from the coupling means and wherein the attachment base can be
removed from the coupling means only by applying a punching force sufficient
to eject
the attachment base of the grinding pad from the coupling means.
In one of its aspects, the coupling means is a metal mounting base and the
method
comprises boring through holes in the mounting base to receive the attachment
base of
the grinding pad in pressure fit therein. The through holes may be formed with
a slight
taper as well as forming the attachment base with a suitable similar taper to
facilitate the
press-fit connection. When the abrasion head is worn after use, the remaining
attachment base in the through hole is removed by pressure punching the
attachment
base with sufficient force to remove it from the hole. A new grinding pad can
now be
installed in the vacated bore by the use of a press. It is pointed out that
the boring of
through holes into the steel mounting base can be accomplished by several
boring
means to configure the hole to produce a frictional fit connection with the
attachment
base of the pads.
In another aspect the method comprises forming the attachment base with a
wedge
shaped form wherein the attachment base with the grinding pad is secured to a
grinding
disc by wedge retention means with the grinding disc and making it easy to
remove the
attachment plate with the wedge retention means. The wedge retention means can
be
formed by spaced retainer plates secured to the top surface of the grinding
disc or by
retention cavities formed about the grinding disc
In a further aspect, the method comprises boring one or more through holes in
a
grinding disc along circular axes of the disc and connecting the grinding pads
in
CA 3007383 2018-06-06
selected ones of the through holes by pressure-fit securing the attachment
base of the
grinding pads in the through holes. The grinding disc is of course removably
secured in
the grinding head assembly of the floor grinding machine.
Referring now to Figures 15A and 15B, there is shown generally at 80 a
grinding pad
component assembly for forming a plurality of grinding pads on a press, not
shown but
obvious. The components of the assembly comprises a support tray 81 formed by
a
steel plate formed with support handles 82 at opposed ends thereof to
transport the
component assemble and position it into and out of a press. On the support
tray 81
there is positioned a mounting plate template 83 having a plurality of cut-
outs 84 shaped
to the contour of the mounting base 28, has herein illustrated there are nine
of such cut-
outs to receive therein, at precise locations, nine mounting bases 28 on each
of which
has been positioned into the top end of their respective through bores two
grinding pads
25. A spacer plate 85 formed with a plurality of oblong shaped bores 86 is
then
positioned over the assembly of mounting bases with the grinding pads 25 top
portion
extending through the oblong bores 86. The thickness of the spacer plate 85 is
the
same as the thickness of the abrasion head 26 of the pads 25. A flat top steel
plate 87
is then placed over the top ends of the grinding pads 25 and the component
assembly is
now completed and ready to be placed on a support platform 88 of a press, see
Figure
15B, where a top press plate 89 is actuated to apply a downward pressure on
the
component assembly until the top steel plate 87 is arrested on the top surface
90 of the
spacer plate 85 causing all of the attachment bases 27 of the grinding pads 25
to be
pressure fitted in their respective through bores 29 and the abrasion heads 26
all
projecting above the top surface 31 of their respective mounting base 21.
Accordingly,
as can be seen a plurality of pressure fit grinding pad assembly can be
manufactured in
a very short period of time and in a safer manner than with the prior art
assembly as
discussed herein above.
It within the ambit of the present invention to encompass all obvious
modifications of
the examples of the preferred embodiment described herein provided such
modifications fall within the scope of the appended claims. As examples only,
the
through bores could consist of holes formed in the top surface of the mounting
base and
16
CA 3007383 2018-06-06
extending partly within the base and with a small hole drilled in a bottom
wall of the hole
for the escape of air to permit the pressure-fit connection of the attachment
base of the
grinding pad within the hole. Also, the attachment base of the grinding pad
can be
formed with a variety of connecting means, such as flanges, tapers, slots in
opposed
side walls, etc., wherein to secure to a complimentary connection means formed
with or
secured to the grinding disc outer surface. As previously mentioned the
abrasion head
to the grinding pad can have several shapes and formed of different grits and
grinding
particles. Also, the attachment base of the grinding pad can be removed from
its
pressure-fit connection in the holes of the metal attachment base or disc by
de-pressing
in a press or by punching the attachment base with an instrument to which a
suitable
punching force can be applied, and as an example, by the use of a steel punch
and
hammer. It is further pointed out that the cross-sectional shape of the pad
attachment
base and the through bores can have a variety of complimentary shapes.
17
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