Note: Descriptions are shown in the official language in which they were submitted.
2 ~
-- 1
46663 CAN 7A
C~NTACT ~;Y3EIEEL AND METE~OD
Technical Field
The present invention relates generally to
back-up supports ~or use in grinding assemblies that
include coated abrasive belts for producing a new surface
on a workpiece, and more particularly to contact wheels
for supporting coated abrasive belts.
Backqround Art
Known grinding assemblies which include coated
abrasive belts entrained over contact wheel~ are adapted
to produce new sur~aces on workpieces, such as forgings
15 or castings. One such grinding assembly is known as a
backstand grinding assembly and comprises a contact wheel
and at least one idler wheel, a means for driving or
rotating the contact wheel, an endless coated abrasive
belt entrained over the idler and contact wheels, a means
20 for tensioning the belt to the appropriate tension and
tracking means for ensuring that the abrasive belt tracks
properly on the contact wheel. The endless coated
abrasive belt includes a backing with front and rear
surfaces and an abrasive agglomerate or granules attached
25 along the front surface by a bond system. The contact or
idler wheel is rotated and drives the endless abrasive
belt. To grind the workpiece, the workpiece is brought
into contact (e.g. manually or automatically) with the
coated abrasive belt which is supported by the contact
30 wheel. The surface or area of contact between the
workpiece and the abrasive belt is referred to in this
application as the abrading interface.
Contact wheels may be constructed from
materials such as cloth, rubber, metal and combinations
35 thereof. Cloth and rubber contact wheels are described
on pages 111-128 of Chapter 5 of Coated Abrasives -
Modern Tool of Industry, Coated Abrasives Manufacturers 7
-- 2 --
Institute, McGraw-Hill Book Company, Inc., first edition,
(1958). Rubber contact wheels may be constructed ~rom
rubber "tires" ranging in Shore A durometer hardness from
20 to 100 which may be vulcanized or molded to aluminum
5 wheels or t~ metal rims mounted on hubs.
Generally, the harder the contact wheel, the
faster the coated abrasive belt removes the stock ~rom
the workpiece (i.e. the higher the "cut rate"). However,
the harder the material used to construct the contact
10 wheel (or the higher the cut rate), the coarser the
resultant surface finish on the workpiece. In some
abrading operations, the hardness of the contact wheel is
typically limited by the requirement that the contact
wheel should conform to the workpiece to be abraded, and
15 a user will generally choose the hardest contact wheel
that will sufficiently conform to the workpiece to be
abraded.
A first known contact wheel is known as a
plain-faced contact wheel. As used in this application
20 "Face" applies to the peripheral surface of the contact
wheel. Plain-faced contact wheels have a generally
cylindrical continuous outer periphery and are utilized
for example, for very fine polishing or burnishing. Such
plain-faced contact wheels assure the maximum belt area
25 in contact with the workpiece and thus the lowest unit
grain pressure at the abrading interface.
A second known contact wh~el is known as a
serrated contact wheel and is generally used for
operations which require an increased stock or material
30 removal rate (i.e. a higher cut rate) r and reduced heat
at the abrading interface. Generally as cut rate
increases, the surface finish on the workpiece becomes
coarser. Thus, serrated contact wheels are particularly
suitable ~or grinding operations which require a large
35 amount of stock remo~al and which may tolerate a
relatively coarse or rougher surface finish, at least
until the workpiece is subsequently polished. One
_ 3 2~ 2
example of such an application is when a casting gate or
flash is ground from a cast part such as a golf club.
Serrations on the periphery of a serrated
contact wheel produce alternate lands and grooves across
5 the entire ~ace of a wheel. The ratio of groove width to
land width, the depth of the groove, the shape o~ the
land, and the hardness of the wheel a~ect the cutting
action (e.g. the cut rate) and performance of the coated
abrasive belt. The existence of the grooves in the
10 serrated contact wheel reduces the workpiece temperature
during the grinding operation, and also increases the
effective pressure at the abrading interface. The
increase in the effective pressure between the abrasive
belt and the workpiece affords a higher cut rate but may
15 lead to side effects such as increased abrasive belt wear
and noise levels. One example of increased
abrasive helt wear is known as ~Ishelling~ wherein the
abrasive grains or agglomerates are prematurely released
from the bond systems of the coated abrasive belts. In
~O some grinding operations, shelling is particularly a
problem at the edge of a serrated contact wheel.
Increasing the groove width of a serrated
contact wheel at the expense of land area increases the
effective pressure until a point is reached where the
25 rigidity of the land and performance of the contact wheel
is adversely affected. Typically, the narrower the land
width, the more likely the land will deflect or flex
during an abrading operation. Such-flexing may result in
fatigue damage especially at the root or the bottom
30 portion of the land. If the groove width is too large,
shelling and destruction of the belt along with damage to
the contact wheel may result due to the increased unit
pressures. If thP groove width is too narrow, cut rate
may be sacrificed. The depth and shape of the land along
35 with the durometer (wheel hardness) govern the point
where further increase in groove width tends to decrease
~ 4 --
effective unit pressure by introducing resiliency and a
heightened potential fGr flexing.
Existing contact wheels and the effects of
factors such as wheel diameter, hardness, eontact area,
5 impact, and serrations on the resultant ground workpiece
are described in "Guidelinles for Grinding", the
Industrial Abrasives Division of Minneso~a Mining and
Man~lfacturing Company (3M) #60-4400-0385-7 ~65.4) VP.
Known rubber contact wheels having serrations
10 extending entirely across their peripheral face have a
tendency to fail or breakdown over time, partlcularly
along their edges. It is believed that such failure may
be attributed to several phenomenon. First, since the
edges of the serrated contact wheel are not supported as
15 well as the middle portion of the contact wheel, the
portions of the lands adjacent the edgss of the contact
wheel are more susceptible to amplified and repeated
flexing which eventually results in fatigue damage and
other types of failure particularly at the root or base
20 of the land adjacent the edge of the contact wheel.
Second, the amplified flexing of the portions of the
lands adjacent the edges of the contact wheel affords
increased penetration of the belt and workpiece into the
grooves resulting in impact between the land and the
25 belt/workpiece. Such impact potentially damages the
contact wheel, belt and workpiece. Additionally, in some
grinding operations the abrasive belts tend to drift from
the edge of a contact wheel and expose the edge of the
~heel to direct contact with the workpiece which may
30 result in damage both to the contact wheel and the
workpiece.
Existing contact wheels also encounter problems
due to their limited usefulness. For example, if a
grinding procedure first requires a high cut rate
35 followed by a second polishing operation, a user may
generally (1) use a serrated faced contact wheel with an
abrasive belt and then (2) use a plain-faced contact
2~6~?.
- 5 -
wheel with the same or finer grade abrasive belt. A
serrated and plain-faced contact wheel may be ganged
together for such a procedure. If the two wheels are not
care~ully aligned, a seam is present at the inter~ace
5 between the wheels which may leave a mark on a workpiece.
If the plain-~aced or serrated contact wheels are located
at locations remote from each other, changing between the
two contact wheels wastes time. Additionally, as
mentioned above, shelling of the abrasive grains and
10 destruction of the edges of the wheel may be problems,
particularly when a serrated contact wheel is used.
Disclosure of the Invention
The present invention provides a contact wheel
15 for use in a grinding assembly for forming a new surface
on an object such as a forging (e.g. a golf club or a
wrench) or a casting (e.g. a golf club or a faucet). The
present invention provides a contact wheel with both
serrated and plain-faced or "support" portions which
20 resists damage to its edges, which increases the cut rate
over conventional serrated contact wheels by providing
increased support for the lands of the serrated portions
to deter undesirable flexing of the lands, which reduces
the potential for damage and premature wear including
25 shelling of an abrasive belt, which reduces the effective
pressure at the abrading interface when the abrading
interface is adjacent the edge of the wheel, and which
affords a single contact wheel so that an operator may
conveniently and efficiently use the serrated portion of
30 the wheel for stock removal and the support portion of
the wheel for finishing.
The contact wheel according to the present
invention is adapted to support an endless coated
abrasive belt during abrading or grinding of a workpiece.
35 The contact wheel comprises a hub having an axis and a
generally cylindrical peripheral surface about the axis,
a generally monolithic contact portion having a
~ 6
cylindrical inner surface coaxial with the hub and which
is mounted on the peripheral surface of the hub, and ~n
outer cylindrical coaxial peripheral face surface having
axial spaced edges. The contact portion has
5 circumferentially spaced parallel elongate grooves having
opposite ends. The grooves are recessed from the face
surface with land parts of the peripheral face disposed
between the grooves. The contact portion has at least
one end of each of the qrooves spaced from the adjacent
10 edge of the face surface to provide a continuous support
part of the peripheral face surface adjacent the adjacent
edge of the face surface.
According to one embodimsnt of the present
invention, only one end of each of the grooves is spaced
15 from the adjacent edge of the face surface. According to
another embodiment of the present invention both ends of
each of the grooves are spaced from the adjacent edges of
the face surface to provide continuous support parts of
the peripheral face surface adjacent both edges of the
20 face surface.
The contact wheel of the present invention may
also be conveniently and efficiently utilized in a novel
method for grinding or abrading a workpiece wherein the
same contact wheel is used in grinding operations which
25 require a first relatively high cut rate for stocX
removal and a second relatively lower cut rate for
finishing. The method of abrading a workpiece using a
single contact wheel comprises the steps of (l) providing
a hub having an axis and a generally cylindrical
30 peripheral surface about the axis, (2) providing a
gener~lly monolithic contact portion having a cylindrical
inner surface coaxial with the hub, and an outer
cylindrical coaxial peripheral face surface having axial
spaced edges, ~3) mounting the cylindrical inner surface
35 of the contact portion on the peripheral surface of the
hub, (4) providing the contact portion with
circumferentially spaced parallel elongate grooves having
2 ~ 2
opposite ends, the grooves being recessed from the face
surface with land parts of the peripheral face disposed
betwesn the grooves, (5~ spacing at least one end of each
of the grooves from the ad~acent edge of the face surface
5 to provide a continuous support part of the peripheral
face surface adjacent the adjacent edge; (6) providing an
endless coated abrasive bel1; adapted to grind the
workpiece, (7) supporting the endless coated abrasive
belt with the contact portion, ~8) grinding the workpiece
lO at a relatively high cut rate at a position generally
adjacent the land parts; and (9) grinding the workpiece
at a different and relatively lower cut rate at a
position generally adjacent the continuous support part.
Brief Descri~tion of the Drawing
The present invention will be further described
with reference to the accompanying drawing wherein like
reference numerals refer to like parts in the several
20 views, and wherein:
Figure 1 is a perspective view of a first
embodiment of contact wheel according to the present
invention illustrating continuous support parts adjacent
both edges of the outer peripheral face of the wheel;
Figure 2 is a sectional view of the contact
wheel shown in Figure 1 taken approximately along line
2-2 of Figure l with portions broken away to show detail;
Figure 3 is a front vertical view of a second
embodiment of contact wheel according to the present
30 invention;
Figure 4 is a schematic illustration of a
grinding assembly which includes the contact wheel of the
present invention and a workpiece to be abraded; and
Figure 5 is a front vertical view of a third
35 embodiment of contact wheel according to the present
invention.
8 --
Detailed Description
Referring now to Figures 1, 2 and 4 of the
drawing, there is shown a first embodimPnt of contact
wheel 10 according to the present invention which is
5 adapted for use with a grinding assembly which includes
a coated abrasive belt for creating a new surface on a
workpiece 4 that may be initially relatively rough, such
as a golf club or wrench formecl by means such as but not
limited to forging mechanisms or investment castings.
Figure 4 schematically illustrates a backstand
grinding assembly 40 which comprises the contact wheel 10
and an idler wheel 42. The grinding assembly 40 includes
a continuous abrasive belt 17 (e.g., the abrasive belt
sold by Minnesota Mining and Manufacturing, St. Paul
15 Minnesota, under th2 trade designation 3M '7Regal" T.M.
Resin Bond Cloth Belts, or the abrasive belts also sold
by Minnesota Mining and Manufacturing Company, St. Paul,
Minnesota, under the trade designation 3M 331D
"Three-M-ite" T.M. Resin Bond Cloth Belts or 3M 359F
~0 "Multicut" T.M. Resin Bond Cloth Belts) having a flexihle
backing with front and rear surfaces 18 and 19, and
abrasive grain or agglomerate attached along its front
surface 18 by a bond system, means for driving or
rotating the contact wheel 10 to thereby drive the
25 abrasive belt 17 in a first direction along a path
relative to the workpiece 4 in the form of any
convantional contact wheel drive mechanism 43, such as,
but not limited to the mechanisms associated with
backstands, polishing jacks or vertical slack belt
30 machines sold by KLK Industries, Crystal, Minnesota, or
G ~ P Industries, Indianapolis, Indiana.
The idler 42 and contact 10 wheels are spaced
and the abrasive belt 17 is entrained over them~ A means
for tensioning the belt 17 to the appropriate tension is
35 provided in the form of any convsntional belt tensioning
device 44 such as pneumatic or spring tensioning or dead
weight mechanisms. A tracking means that ensuras the
- 9 -
abrasive belt 17 tracks properly is provided in the form
of any conventional belt tracking device 46, such as
crowned idler wheels, center pivot tracking systems or
pneumatic trackers. The contact wheel 10 is rotated by
5 the contact wheel drive mechanism 43 (alternatively the
idler wheel 42 may be rotated) and drives the endless
abrasive belt 17 which also rides over the idler wheel
42. During grinding, the contact wheel 10 supports the
coated abrasive belt 17 at the abrading interface (Figure
10 4~.
While the belt grinding assembly 40 has been
described with reference to a backstand grinding assembly
it should be noted that the contact wheel 10 and the
method according to the present invention may be
15 practiced with any suitable grinding assembly that
utilizes contact wheels such as, but not limited to,
grinding a~semblies with endless and non-endless abrasive
belts, and grinding assemblies with a plurality of idler
wheels. For example, the bench, formed wheel,
20 conveyorized, centerless, surface, flexible bed sheet,
rotary table surface, and swing yrinders (described on
pages 19-21 of Metalworking, Reference Manual, published
by the Industrial Abrasives Division of ~Iinnesota Mining
and Manufacturing, ~60-4400-036~-7 (1294)JR) may utilize
25 the contact wheel and method of the present invention.
Referring now to Figures 1 and 2 there is shown
a first embodiment of contact wheel 10 according to the
present invention. The contact wheel 10 comprises a hub
11 having an axis and a generally cylindrical peripheral
30 surface 12 about the axis. The hub 11 may be
constructed of metal or a high strenqth plastic and
includes surfaces defining an arbor hole 22 for mounting
the wheel 10 on a suitable drive shaft for the drive
mechanism ~3.
The contact wheel 10 also comprises a generally
monolithic contact portion 24 having a cylindrical inner
surface 25 coaxial with the hub 11 and mounted on the
2 ~
-- 10 --
peripheral surface 12 of the hub 11 by any suitable
methods such as vulcanization, mechanical fasteners,
molding or chemical bonding, and an outer cylindrical
coaxial peripheral face surface 27 having axial spaced
5 edges 32 and 34. The contact portion 24 ha~
circumferentially spaced parallel elongate grooves 53
having opposite ends 54 and 56. The grooves 53 are
recessed from the face surface 27 with land parts of the
peripheral face surface 27 dispo~ed between the grooves
10 53. The grooves may be disposed at an angle relative to
the axis of the hub between 5 and 85 degrees and are
preferably disposed at an angle between 30 and 50
degrees. The contact portion 24 has at least one
end 54 or 56 of each of the grooves 53 spaced from the
15 adjacent edge 32 and 34 of the face surface 27 to provide
a continuous support or "smooth" part 36 of the
peripheral face surface 27 adjacent the adjacent edge 32
or 34 of the face surface 27. The embodiment of wheel 10
shown in Figures 1 and 2 includes two support parts 36
20 adjacent the edges 32 and 34 of the wheel 10. The
contact portion 24 may be constructed from any suitable
material such as cloth or an elastomer such as natural or
synthetic rubber having a Shore A durometer hardness
preferably between 20 and 100.
25The support part 36 is adapted to reduce damage
to the endless coated abrasive belt 17, since the support
part 36 assures the maximum belt area in contact with the
workpiece 4 at the edges of the contact wheel 10 and thus
provides the lowest unit pressure at the edges 32 and 34
30 of the contact wheel 10. Lowering the unit grain
pressure at the edg~s 32 and 34 of the contact wheel 10
tends to reduce the potential for shelling of the
abrasive belt 17 resulting in extended life for the belt
17.
35The support part 36 also prevents damage to the
contact wheel 10 and provides an increased cut rate as
the support part 36 provides support for the land parts
2 0 ~ 2
-- 11 --
of the peripheral face surface 27 to reduce undesirable
flexing. The reduced flexing of the lands diminishes the
potential for fatigue damage to the lands, particularly
at their roots or bases.
Should a belt 17 fail to track properly (e.g.
a mistract) and expose an edge 32 or 34 of the wheel 10
to direct contact with the workpiece 4, the support part
36 assures the maximum edge area in contact with the
worXpiece 4 and thus provides t~le lowest unit pressure at
10 the edges of the contact wheel 10 to thereby deter
breakage or other damage to an edge 32 or 34 of the
contact wheel 10 or to the workpiece 4. The support part
36 also acts as a barrier to restrict penetration of the
belt 17 and workpiece 4 into the grooves 53 at the edge
15 32 or 34 of the contact wheel lo reducing the potential
for impact between the workpiece 4 and wheel 10.
~ he surface area ratio of the lands to grooves
will depend on the particular abrading application and
may typically range from 1:9 to 9:1. An exampl~ of a
20 wheel according to the embodiment shown in Figure 1 may
have a diameter from the axis of the hub 11 to a radially
outer point on a land on the peripheral face surface 27
of approximately 35.7 centimeters with and overall width
of the face surface 27 between ends 32 and 34 of about
25 7.6 centimeters and with the width of each of the support
portions 36 ~eing approximately 1.25 centimeters. The
width of an individual land may be approximately 0.95
centimeters and the width of an individual groove may be
about 0.95 centimeters. It should be noted that these
30 dimensions are for purposes of describing the invention
and are not intended to be limiting.
Figure 3 illustrates a second alternative
embodiment of contact wheel according to the present
invention with the contact wheel generally designated by
35 the reference character 20 which has many parts that are
esRentially the same as the parts of the contact wheel 10
- 12 -
and which have been identified by the same reference
number to which the suffix "A" has been added.
Like the contact wheel 10 described in Figures
1 and 2, the contact wheel 20 shown in Figure 3 comprises
5 a hub having an axis and a generally cylindrical
peripheral surface about the axis. The hub includes
surfaces defining an arbor hole for mounting the wheel 20
on a drive mechanism.
The contact wheel 20 also comprises a generally
10 monolithic contact portion 2~A having a cylindrical inner
sur~ace coaxial with the hub and mounted on the
peripheral surface of the hub, and an outer cylindrical
coaxial peripheral face surface~27A having axial spaced
edges 32A and 34A. The contact portion 24A has
15 circumferentially spaced parallel elongate grooves 53A
having opposite ends 54A and 56A. The grooves 53A are
recessed from the face surface 27A with land parts of the
peripheral face surface 27A disposed between the grooves
53A. The contact portion 24A has both ends 54A and 56A
20 of each o~ the grooves 53A spaced from the adjacent edges
32A and 34A of the face surface 27 to provide a
relatively narrow continuous support part 36A adjacent
one edge 34A of the peripheral face surface 27A and a
relatively wide continuous support part 72 adjacent the
25 other adjacent edge 32A of the face surface 27A.
The contact wheel 20 has a width W and a
diameter Y. The width W may range from approximately 1.5
inches (3.8 centimeters) to about 100 inches (254
centimeters) and the diameter Y of the wheel 20 may range
30 from about 2 inches (5.1 centimeters) to approximately 30
inches (76.2 centimeters).
Unlike the contact whsel 10, the contact wheel
shown in Figure 3 comprises a relatively wide
continuous support part 72 having a length X. For
35 example, a contact wheel with a diameter of 14 inches
(35.7 centimeters) and a width of 6 inches (15.2
centimeters) may have a relatively wide continuous
C~
- 13 ~
support part 72 with a length of 3 inches (7.6
centimeters). The relatively wide continuous support
part 72 is particularly suitable for use in a method of
abrading a workpiece using a single contact wheel which
5 is discussed later in this application.
The support parts 36A and 72 are adapted to
reduce damage to the endless coated abrasive belt 17,
since it is believed that the support parts 36A and 72
assure the maximum belt are.a in contact with the
10 workpiece 4 at the edges of the contact wheel 20 to
reduce the unit pressure at the edges 32A and 34A of the
contact wheel 20. Similar to the support part 36 of the
wheal 10, the support parts 36A and 72 also deter damage
to the contact wheel 20 as the support parts 36A and 72
15 provide support for the land parts of the peripheral face
surface 27A to limit their flexing.
Figure 5 illustrates a third alternative
embodiment of contact wheel according to the present
invention with the contact wheel generally designated by
20 the reference character 30 which has many parts that are
essentially the same as the parts of the contact wha~l 20
and which have been identified by the same reference
number to which the suffix "A" has been replaced by the
suffix "B".
Like the contact wheel 20 described in Figure
3, the contact wheel 30 shown in Fiyure 5 comprises a hub
having an axis and a generally cylindrical peripheral
surface about the axis. The hub includes surfaces
defining an arbor hole for mounting the wheel 30 on a
30 drive mechanism. The contact wheel 30 also comprises
a generally monolithic contact portion 24B having a
cylindrical inner surface coaxial with the hub and
mounted on the peripheral surface of the hub, and an
outer cylindrical coaxial peripheral face surface 27B
35 having axial spaced edges 32B and 74. The contact
portion 24B has circumferentially spaced parallel
elongate grooves 73 having an end 75 and an end 79. The
- 14 -
grooves 73 are recessed from the face surface 27B with
land parts of the peripheral face surface 27B disposed
betwe~n the grooves 73. The contact portion 24B has the
end 75 of each of the grooves 73 spaced from the adjacent
5 edge 32B of the face surface 27A to provide a relatively
wide continuous support part 72B.
Unlike th~ contact wheels 10 and 20, the outer
peripheral face surface 27B of the contact wheel 30
includes only a single support part 72B adjacent the edge
10 32B of the peripheral surface 27B. At khP other edge 74
of the peripheral surface 27B, the grooves 73 extend to
the edge 74 of the wheel 30. The ratio of the diameter
to the width of the contact wheel 30 may be approximately
4:1 and is particularly suitable for use with a
15 relatively wide belt abrasive, such as an abrasive with
a width of 14 inches (35.56 centimeters) or qreater.
OPERATION
The present invention may also be described as
20 a method of abrading a workpiece using a single contact
wheel comprising the steps of (1) providing a hub having
an axis and a generally cylindrical peripheral surface
about the axis, ~2) providing a g~nerally monolithic
contact portion having a cylindrical inner surface
25 coaxial with the hub, and an outer cylindrical coaxial
peripheral face surface having axial spaced edges, (3)
mounting the cylindrical inner surface of the contact
portion on the periphsral surface of the hub, (4)
providing the contact portion with circumferentially
30 spaced parallel elongate grooves having opposite ends,
the grooves being recessed from the face surface with
land parts of the peripheral fac~ disposed between the
grooves, (5) spacing at least one end of each of the
grooves from the adjacent edge of the face surface to
35 provide a continuous support part of the peripheral face
surface adjacent the adjacent edge; (6) providing an
endless coated abrasive belt adapted to grind the
- 15 -
workpiece, (7) supporting the endless coated abrasive
belt with the contact portion, (8) grinding the workpiece
at a relatively high cut rate at a position generally
adjacent the land parts; and (9) grinding the workpiece
5 at a different and relatively lower cut rate at a
position gen~rally adjacent the continuous support part.
The embodiments of contact wheels shown in
Figures 3 and 5 are particularly suitable for use in the
method of abrading a workpiece using a single contact
10 wheel according to the present invention. The workpiece
4 may be a golf club formed by a casting process which
leaves a casting gate or flash on the golf club. The
operator may first grind the flash or gate from the golf
club at an initially aggressive, high cut rate and
15 subsequently grind the surface of the golf club at a
different relatively lower cut rate to provide a finer
finish or smooth surface on the golf club.
U~ing the method and contact wheel of the
present invention, the operator may first grind the golf
20 club at a position generally adjacent the land parts of
the wheel 20; and then at a different and relatively low
cut rate at a position spaced from the land parts (e.g.
adjacent the support part 72) to produce a finer,
finished surface on the golf club. Tha user is spared
25 the additional task of using a different contact wheel
(such as a plain-faced contact wheel) for the low cut
rate/finer finish operation. Thus, an operator may
accomplish two tasks without moving from a single
grinding station. Thus, it is believed that the method
30 of the present invention may save operator time during
some grinding operations.
The present invention has now been described
with reference to several embodiments thereof. It will
be apparent to those skilled in the art that many changes
35 can be made in the embodiment described without departing
from the scope of the present invention. For example,
the contact wheel of the present invention may comprise
a shaped contact wheel including a hub having an axis,
and a generally monolithic contact portion including an
outer peripheral face surface having axial spaced edges
which peripheral face surface is not cylindrical and
5 coaxial with the hub but which is instead intentionally
shaped in the form of a new surface to be ground on a
workpiece. Additionally, the contact wheels of the
present invention may include grooves that extend
completely around the periphery of the wheel, that are
10 generally coaxial with the axis of the hub and that do
not include ends (e.g. the contact wheels sold by
Minnesota Mining and Manufacturing, St. Paul Minnesota,
under the trade designation 3M "Serr-X" T.M. Contact
Wheels) so long as the wheel also includes at least one
15 end of other grooves being spaced from the adjacent edge
of the face surface to provide a continuous support part
of th~ peripheral face surface adjacent the adjacent
edge. Also, the contact wheel of the present invention
may comprise a contact portion having portions having a
20 different hardness or durometer ~e.g., the contact wheel
30 shown in FIG. 5 may have a serrated portion with a
harder durometer than the plain faced portion).
