Note: Descriptions are shown in the official language in which they were submitted.
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ARBORS & FASTENERS TO AFFORD TV~~O FORMS OF
EASY/QUICK CHANGE MOUNTING FOR ABRASIVE DISCS
Field of the Invention
[0001] This invention relates generally to abrasive finishing articles and
more
particularly, to a mounting structure for attaching coated abrasive finishing
articles to the
drive member of a power tool and to a coated abrasive finishing article with
the mounting
structure attached thereto..
Description of the Prior Art
[0002] The use of rotatably driven abrasive finishing articles and
particularly
coated abrasive finishing articles such as discs is widespread and familiar in
our industrial
society. Traditionally, such an abrasive disc is removably attached by way of
a hub assembly
including a disc support pad to a power tool. When the hub is rotated, the
disc rotates with it
permitting the moving disc abrasive surface to effectively finish the surface
of worlc pieces.
A variety of hub structures have been used in the prior art to secure the
abrasive finishing
disc to the power tool.
[0003] The earliest and very coimnon of such structures includes a support pad
having a reinforced central aperture arranged to be engaged over the threaded
end of the
rotary shaft of the power tool. The abrasive finishing disc is placed on the
flat surface of the
pad and a flanged nut is turned down onto the threaded end of the rotary shaft
protruding
through the disc. When the nut is tightened, the flange lays flush against the
abrasive surface
of the disc and clamps the disc to the support pad.
[0004] This traditional mode of attaching the abrasive finishing disc to the
rotary
power tool has two major disadvantages. The first of these is that in
engagement of the
rotating finislung disc against the worlc piece, a large amount of torque is
imparted to the hub
which tends to tighten the nut onto the threaded shaft of the power tool
making it quite
difficult to remove the nut in order to replace the disc after it is spent and
usually involves the
use of tools. In many heavy industrial applications, such abrasive discs have
to be replaced
quite often. As a result, when considering the number of power tools which may
be in use at
any given time, there is an excessive amuunt of downtime necessitated by such
disc
replacement. The second disadvantage is that the flange of the nut extends
onto the abrasive
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surface of the finishing disc and the worker must be quite careful to prevent
the flange on the
nut from engaging the work piece which in most cases would impart damage to
the work
piece.
[0005] In order to avoid the problems above referred to, a quick release
abrasive
finishing disc hub was developed and is most clearly shown in U.S. Patent Nos.
3,667,169
and 3,667,170. As is disclosed therein, an adapter is provided which is
adhesively adhered to
the baclc surface of the abrasive finishing disc. One form of such adapter
includes a raised
boss having a central aperture whose rim is turned inward and shaped to form a
screw thread
which receives the threaded end of a stud attached to the power tool or the
end of the power
tool shaft. Another form is a threaded stud which engages a threaded bore on
the power tool
shaft. This allows the user to attach or remove the abrasive disc to the power
tool rather
quickly. It is appaxent that through the utilization of such devices, the
attaching structure is
disposable along with the spent disc. As above noted, the attaching structure
is an adapter
formed to have a screw thread and is adhesively secured to the back of the
coated abrasive
disc. Such structures increase the cost of the materials and labor used in the
abrasive
finishing process.
[0006] In view of the foregoing disadvantages of the prior art coated abrasive
finishing disc mounts, it is desirable to provide a mounting device for coated
abrasive
finishing articles and particularly a coated abrasive finishing disc which is
reusable or
expendable and will provide the ability for the user to quickly and easily
remove and mount
abrasive finishing discs upon a portable power tool without the need for
wrenches,
screwdrivers, or other tools with or without the attachment of external
adapters or other
attachment devices directly to the abrasive finishing discs.
[0007] A typical attachment of the type above referred to for securing a
coated
abrasive disc having a central aperture to the power tool with a nut having a
flange is hown
by the patent to G. L. Bryson, U.S. Patent No. 2,699,020. An additional type
of quick change
structure in addition to the patents above referred to which includes an
adapter secured to the
abrasive discs is shown by the patent to Field, U.S. Patent No. 3,653,858.
Summary of the Invention
[0008] A disposable, reusable mounting apparatus for rotatably securing a
coated
abrasive finishing article to the drive member of a power tool which includes
a support
member and a nut adapted to extend through an aperture in the finishing
article for engaging
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the finishing article with the power tool which comprises an outer surface on
the body of the
nut which is adapted to engage an edge of the aperture through the finishing
article in an
interference fit and an externally threaded shanlc for engagement with the
power tool drive
member, a support pad is provided defining a centrally located aperture and a
face to engage
the abrasive finishing article with the support pad having a reduced tluckness
region adjacent
and surrounding the aperture therethrough. The support member further includes
a hollow
externally threaded cylinder having an outwardly extending flange at one end
thereof and a
compression ring. The support pad is secured between the flange and the
compression ring to
secure the support pad upon the cylinder. The end of the cylinder having the
flange defines a
recess to receive a flange extending outwardly from one end of the nut so that
when
assembled in operational configuration, the flange on the nut is below the
abrasive finishing
article surface so that it cannot engage a worlc piece during use.
(0009] In the reusable mounting apparatus of the present invention the
mounting
nut includes an irregular surface on the body of the nut which is adapted to
engage an edge of
the aperture through the finishing article in an interference fit and when the
coated abrasive
finishing article is spent the nut may be popped out of the aperture in the
finishing article and
then reused with a new finishing article by inserting the nut through the
central aperture
therein.
[0010] In the disposable mounting apparatus of the present invention the nut
is
formed of a plastic material and further includes a retention member which
engages the body
of the nut immediately adjacent the finishing article in am interference fit
to secure the nut to
the finishing article with the combination of the nut and the finishing
article being disposed
of when the finishing article is spent.
Brief Description of the Drawings
[0011] Figure 1 is a cross-sectional view of a coated abrasive finishing disc
assembled with the reusable mounting device of the present invention;
Figure 2 is a partially exploded view of the structure as illustrated in
Figure 1;
Figure 3 is a partially exploded view of an embodiment of a disposable
mounting
stnzcture in accordance with the present invention;
Figure 4 is a sideview of a disposable abrasive finishing disc with the nut of
the
present invention secured thereto;
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Figure 5 illustrates the reusable attachment nut constructed in accordance
with the
principles of the present invention secured to a coated abrasive disc; and
Figure 6 illustrates in cross-section schematically one embodiment of a
support pad
constructed in accordance with the principles of the present invention.
Detailed Description
[0012] Referring now more particularly to Figure 1 there is illustrated
schematically in cross-section, an reusable or reusable mounting device for
coated abrasive
discs constructed in accordance with the principles of the present invention
with a coated
abrasive member secured thereon. As is illustrated in Figure 1, the support
member
constructed in accordance with the present invention is adapted to secure an
abrasive
finishing article 10 in the form of a coated abrasive disc having a first
surface 12 with
abrasive finishing material thereon and a second uncoated surface 14 on the
opposite side
thereof. The disc 10 defines an aperture 16 centrally disposed therethrough. A
nut 18 having
a flange 20 extending outwardly from one end thereof is pushed through the
aperture in such
a manner that an outer surface 22 having an iiTegular configuration forms a
substantially
interference fit with the edge 24 of the aperture. As will be described more
fully herein
below, the irregular surface may be formed by a plurality of alternating
ridges and grooves
which may take any shape desired and preferably would be disposed parallel
with the axis 26
of the nut. The nut includes a shanlc 26 which is externally threaded so as to
be received
within the threaded end 28 of a drive member 30 which is adapted to be affixed
to a power
tool (not shown) but well lcnown to those spilled in the art. A support pad 32
is provided and
has a surface 34 which engages the surface 14 of the abrasive disc 10. The
support pad also
defines an aperture 35 centrally disposed therethrough. The surface 34 of the
support pad 32
immediately adjacent the opening 35 therethrough has a reduced thicl~ness
which is adapted
to receive a second flange 36 on a cylinder 42. The support pad 32 in
accordance with a
preferred embodiment of the present invention is useful with smaller discs and
includes a
semi-rigid member 38 which may be formed of plastic having an elastomeric
material 40
secured thereto with the elastomeric material 40 engaging the surface 36 of
the abrasive disc
10. The support member further includes the hollow cylindrical member 42
having an
externally threaded surface 44. Threadably secured upon the external surface
44 is a
compression ring 46. As is shown, the support pad 32 is disposed upon an
outwardly
extending lip or flange 36 of the cylindrical member 42. It should be apparent
to those
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skilled in the art that the support pad 32 is captured between the flange 36
and the
compression ring 46. It should also be noted that the flange 36 is received
within the reduced
thiclcness area of the support pad 32. The end of the cylinder adjacent the
flange 36 defines a
recess which is adapted to receive the flange 20 on the nut 18 so that when
assembled on the
mounting device, the flange 20 is below the abrasive finishing to particles on
the surface 12
of the disc 10 to preclude the flange coming into contact with the worlc
piece.
[0013] If desired, an additional baclcing member or disc 50 may be provided
along
with the support pad 32 to provide additional rigidity. Depending upon the
application and
the rigidity desired, the additional bacleup disc 50 maybe constructed of
metal. Under those
circumstances, it may also be desirable to provide an elastomeric washer 52
which is seated
between the metal disc 50 and the compression ring 46 to assist in securing
the back pad and
supporting discs in proper relation to provide the support desired for the
abrasive finishing
disc 10.
[0014] As is further shown in Figure 1, the drive member 30 includes a flange
54
which seats against a surface 56 of the cylinder 42. The cylinder 42 defines
an opening 58
through which the drive member extends. The lower portion of the drive member
extending
through the opeung 58 carries an O-ring 60 which provides frictional
engagement with the
opening 58. Through the frictional engagement, the support member is retained
upon the
drive member 30 during the time the coated abrasive disc 10 is detached for
removal and
replacement after it is spent. It is an important feature of the present
invention that the
support member ~s not in any way threadably attached to the drive member 30.
It should be
recognized that the support pad 32 along with the abrasive disc 10 is
rotatable with respect to
the drive member 30. As a result, the abrasive disc 10 and the support pad 32
may be rotated
by hand to attach the nut 18 to the threads 28 on the drive member 30. Also,
together (or
simultaneously) the support pad along with the disc may be rotated in the
opposite direction
by hand once the disc is spent to remove the nut 18 from the threaded bore 28
of the drive
member 30.
[0015] Refernng now, more particularly, to Figure 2, the reusable attaching
apparatus in accordance with the present invention is illustrated in partially
exploded
schematic fashion without the abrasive disc. The same reference numerals are
utilized for the
same parts as set forth in the description of Figure 1. By reference to Figure
2, the recess on
the end of the cylinder adjacent the flange 36 is more clearly shown at 64.
The flange 20 on
the nut 18 seats within the recess 64 with the coated abrasive disc trapped
between the flange
20 and the bottom of the recess 64 to thus cause the flange 20 to be
positioned below the
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outer surface of the abrasive disc (below the surface of the abrasive
particles) so that it will
not come into contact with the work piece. The irregular surface 22
constructed as a plurality
of alternating ridges and grooves which cut through the edge of the aperture
35 in the
abrasive disc 10 are more clearly illustrated in Figure 2. As shown, the drive
member 30 is
an arbor that may be inserted into the chuck or collet of a portable power
tool.
[0016] It should also become more clear from the illustration shown in Figure
2
that the only threaded engagement with the drive member 30 which is
interconnected to the
power tool at any portion of the mounting member is between the threads 28 on
the drive
member 30 and the external threads on the shank 26 of the nut 18.
[0017] By referring now more particularly to Figures 3 and 4, there is
illustrated
that embodiment of the present invention which is intended to be disposable
after the abrasive
finishing article is spent during use. Figure 3 illustrates the components of
the invention
schematically and in exploded view. As is therein shown an abrasive finishing
article 62
including abrasive particles 64 on one surface thereof has an uncoated surface
66 on the
opposite side thereof. A central aperture 68 is provided through the abrasive
finishing article
62. A securing, nut 70 is provided. The nut 70 for this embodiment of the
invention is
formed preferably from an extruded rod of polyvinylchloride plastic material.
The plastic
material is then formed in an automatic screw machine to provide a blank which
includes a
flange 72 and a body 74 which extends the entire length of the nut 70 as shown
in Figure 3.
The body 74 has a first diameter dl. This blanlc without the threads is then
placed into a
feeder bowl and from there to a thread rolling machine. The thread rolling
machine then
forms the threads 76 on the lower portion of the body 74. A standard thread
rolling machine
is utilized for this purpose even though such machines traditionally are used
to form threads
on metal blanks. Also provided is a washer 78 which defines a second aperture
80
therethrough. The second aperture 80 has a second diameter d2. The second
diameter d2 is
no larger than the first diameter dl and preferably may be slightly less than
the diameter d1
so that when the assembly of the components as shown in Figure 3 is completed,
as will be
described more fully in conjunction with Figure 4 below, the washer 79 engages
the body 74
of the nut 70 in an interference fit.
[0018] The completed structure of the disposable abrasive finishing article is
shown in Figure 4. As is therein illustrated the flange 72 is completely below
the surface 64
of the abrasive particles on the finishing article 62. It should be noted that
the nut 70 has
been inserted through the aperture 68 through the utilization of an assembly
jig (not shown)
which simulates the depression 64 as shown more clearly in Figure 2. Thus, the
disc is
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formed around the flange 72 and the washer 78 is forced into an interference
fit with the body
74 of the nut 70. When the washer is forced over the body 74, it is canted or
tilted to assume
the slope of the surface 66 of the abrasive disc 62. Such canting causes the
edge of the
washer defining the aperture to cut into the body 74 to more securely fasten
the nut and disc
together. Such construction causes the abrasi ve disc 62 to more readily fit
upon the support
pad and structure of the type as shown in Figure l and Figure 2. It will be
readily recognized
by those spilled in the art that the disc with the disposable nut as
illustrated in Figure 4
readily fits upon the support pad as shown in Figures 1 and 2.
[0019] Referring now more particularly to Figure 5, the cooperative
relationship
between the abrasive disc 10 and the nut 18 is better illustrated for reusable
use. As is shown
therein, the shanl~ 92 of the nut 18 has formed thereon the irregular surface
22 in the form of
alternating ridges and grooves which preferably are substantially parallel to
the longitudinal
axis of the nut 18. Preferably the nut 18 for reusable use is constructed of
steel that has been
machined to the desired form and then case hardened. When the nut 18 is forced
into place
through the central aperture formed in the abrasive disc 10, the ridges cut
into the surface
defining the central aperture in such a way that an interference fit is
formed.between the nut
18 and the central aperture in the abrasive disc 10. The interference fit then
provides the
ability to tunz the disc 10 and at the same time, turn the nut 18 so that the
threads formed
internally in the bore provided therein engage the threads 28 on the drive
member 30. thus,
pulling the flange 20 on the nut 18 down and into the recess 64 carrying with
it that portion of
the abrasive disc 10 immediately surrounding the aperture through which the
shanlt 92 has
been extended thereby clamping the disc 10 in place on the support pad 32 for
use. It is
important to note that the flange 20 is completed below the abrasive particles
on the finishing
surface of the disc and therefore cannot contact the worlc piece. This
provides the additional
advantage of increasing the amount of surface available for use in finishing
of the worlcpiece
surface. It should be understood by those spilled in the art that the abrasive
disc 10 may be
constructed of any coated abrasive material know to those skilled in the art,
for example, the
disc 10 may be formed of cloth, paper, vulcanized fiber, or the like.
[0020] Referring now, more particularly, to Figure 6, the support pad 32 is
shown
in greater detail and the reduced diameter area is shown more clearly at 94.
The plastic
material of the support pad 32 as shown at 96 may be any type of plastic
material desired but
preferably, would be molybdenum disulfide filled nylon material.
[0021] There has thus been disclosed a mounting device for a coated abrasive
finishing article in a form which may be reused indefinitely and which permits
easy
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attachment and detaclnnent by hand without the use of tools for the
replacement of spent
abrasive discs. Alternatively, the momting device may be in a form which is
permanently
secured to the disc and discarded therewith when the disc is spent. The
mounting device is
constructed in such a manner that the nut for attaching the abrasive disc to
the support
member is recessed below the surface of the abrasive disc and thus will not
contact a work
piece during use.
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