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Патент USA US3078847

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Feb. 26, 1963
P. R. THOMAS
3,078,835
METHOD FOR DRESSING GRINDING WHEELS
Filed May 27, 1960
_
_
INVENTOR.
Philip R Thomas
HIS A TTORNE Y
3,078,835
Patented Feb. 26, 1963
2
3,078,335
METHGl) FOR DRESSING GRINDING WHEELS
Philip R. Thomas, Livonia, Mich, assignor to The Car
borundurn Company, Niagara Falls, N.Y., a corpora
tion of Delaware
tional passes using an infeed of .0005” per pass and two
passes using an infeed of .0002” per pass. The open dress
is quicker, but the ?ne dress produces a better ?nish.
Irrespective of which technique is used, it is common to
encounter a taper condition which must be manually
corrected by adjustment of the axes of rotation of the
grinding wheel and the regulating wheel so that the faces
of the two wheels are aligned, i.e., so disposed that the
This invention relates to the art of cylindrical grinding,
portions of the wheels which contact the work piece are
and more particularly to a method of dressing centerless 10 parallel within the permissible tolerance. This trouble
some and time-consuming operation can be eliminated by
grinders and to a dressing pin used therein. Further,
this invention relates to a method of dressing wheels for
the use of my invention.
My new method comprises passing a diamond coated
center-type grinders and to a wheel dresser for use therein.
dressing pin through the centerless grinder after the con
Centerless grinding wheels are well known in the art.
They are particularly useful for precision work in which 15 ventional open or ?ne dress has been completed. The
feed or speed at which the pin is run through the grinder
large numbers of relatively small pieces are to be ground
and the ground surfaces bear no exact relationship to
is not critical. However, I prefer to use the same feed
as will be used in the grinding operation. This step
another surface except as a whole. No chucking of the
corrects for small inaccuracies of machine set since it
work on mandrels or other holding devices is required,
yet the work is rigidly supported and there is no tendency 20 not only dresses the grinding wheel but also dresses the
feed wheel to produce a dead-true alignment. Where the
for chatter or de?ection of the work. Since a true floating
dressing pin is the same diameter as the ?nish dimension
condition exists during the grinding process, less grinding
of the workpiece, the ?nal precise adjustment of the
stock is required. Less skill is required in the operation
machine by hand is eliminated since this is done by the
of centerless grinders than in the operation of other
cylindrical grinders. However, in order to obtain precise 25 pin which trues both the grinding and feed wheels into
dead true alignment. Furthermore, the use of a diamond
work having a minimum taper and a high ?nish, the
dressing pin eliminates irregularities in the wheel surface
center-less grinder must be meticulously adjusted. Such
and any build-up on the work rest blade.
adjustments are not only diflicult to make, but require
As shown in FIGURE 3, a diamond dressing pin 19,
substantial time while the machine is idle. My invention
used in my new method, comprises a steel core 20 to
provides a method whereby precise adjustment can be
which an abrasive section 22 consisting of bonded
made with little effort and in a minimum amount of
diamond grains is brazed. Any conventional type of
time. I have found that by passing a diamond impreg
bond may be used. I have successfully used a tungsten
nated pin through a centerless grinder, the grinder can
Filed May 27, 1960, Ser. No. 32,150
4 Claims. (Cl. 125—11)
new
M.e
be automatically adjusted and the ?nal precise manual
carbide and cobalt bond. In that instance, a mix con
35 sisting of .375 gram of diamond grit, 2.99 grams of
adjustment now required can be eliminated.
tungsten carbide and 2.45 grams of cobalt was hot pressed
This invention also provides a method for improved
in a graphite mold at a temperature of approximately
dressing of grinding wheels used in center-type grinders
1300" C. and a pressure of 3000-4000 psi. to form an
and to a wheel dresser for use therein.
‘abrasive section 1/2” long having an inside diameter of
In the drawings, FIGURE 1 is a diagrammatic view of
40 %" and an outside diameter of %". Three such sec
a centerless grinder;
tions were brazed to a steel core %” in diameter and
FiGURE 2 is a side elevation of the grinder shown in
FEGURE 3 is a longitudinal section taken through a
11/2" long.
The following speci?c examples will serve to illustrate
diamond dressing pin made according to this invention;
the effectiveness of my invention as applied to centerless
and
FIGURE 4 is a plan view of a pin-type wheel dresser,
made in accordance with the present invention, for use
in dressing a center-type grinding machine wheel.
As shown in the drawings, a centerless grinder com
prises a grinding wheel 10- and a regulating wheel 12.
A Cincinnati Centerless Grinder having a
bonded 60 grit alumina grinding wheel with a
ameter and 6" face and a rubber bonded 80 grit
regulating wheel with'an 11" diameter and a
FEGURE 1;
7 Any conventional grinding wheel such as a vitri?ed
bonded alumina wheel may be used.
grinding.
Example I
vitri?ed
20" di
alumina
6" face
was used to compare an open type dress without a pin
The regulating
dress and an open type dress followed by a pin dress
according to my invention. Also, in one instance, the
is composed of a rubber-bonded abrasive such as alumina.
open type dress was followed by the customary precise
A work piece 14 is supported between the wheels 10 and
manual adjustment. The dressing tool was of the cluster
12 on a work rest 16. The regulating wheel 7.2v has
type, a cluster of diamonds being embedded in the end
frictional characteristics which enable it to rotate the
of 1a tungsten carbide rod. The work rest blade was made
work at its own rotational speed. Axial movement or"
of tungsten carbide and had a 30° angle. A 2° draw
the work past the grinding wheel is obtained by tilting
angle was used. The diamond dressing pin was 11/2" long
the regulating wheel at a slight angle from the horizontal 00 and %" in diameter consisting of a 1/16" thick abrasive
as shown at 18 in FIGURE 2. This angle may vary
section brazed to a mild steel pin. The results of the
from 0 to 8 or 10 degrees. The larger the angle, the
tests are tabulated below.
faster the rate of feed.
wheel is generally smaller than the grinding wheel and
Two types of dressing are generally used for grinding
wheels.
Type 01' Dressing
In an open dress technique, a diamond tipped
Finish
Max.
(M.I.)
Taper
dressing tool is passed over the surface of the grinding
wheel as many times as necessary to true up the wheel
at an infeed of about .001” per pass and at a lateral speed
of about 20” per minute. In ?ne dress technique, the
70
lateral speed is reduced to 4" per minute and the initial
infeed passes at .001" per pass are followed by two addi
Open-No pin ___________________________ __
D0
D0
28
_
_
Open-Pin ______________________________ ._
D0
‘
D0
_
Open—Precise AdJustment ______________ __
____________ __
0007
_-
010
19
19
0001
0002
.0001
. 0001
8,078,836
3
A test was also made identical in all respects to that
discussed in Example I except that a ?ne dress was sub
stituted for the open dress of Example I. The results
is 1/2" or greater, the structure will preferably contain
a steel core, because of economic considerations.
are tabulated below.
Type of Dressing
Fino~No pin ____________ __
Finish
Taper
10-23
.0004
Fine-Pin ________________ __
8
.0001
Fine-Precise Adjustment"
l4
. 0001
10
The foregoing results show clearly that by using my
ness in the range from about 1/32" to about '~}f;g”.
Bonds applicable to use in forming the abrasive sec
tion of pins of the present invention include bronze,
tungsten carbide, steel and the like. The essential factor
is that the bond be very strong to retain the grains of
diamond in place during the dressing operation and thus
new process and dressing pin, the ?nal precise adjust
ment of the centerless grinder may be eliminated without
any sacri?ce in accuracy of the set.
In
the larger sizes, the bonded diamond grain will have a
thickness in the range from about liég" to about Mr”.
Preferably the bonded diamond grain will have a thick
Max.
(M.I.)
4
in all instances, it is preferred for convenience of manu
facture, to form the pin entirely of bonded diamond grain
when the diameter is less than 1/2". When the diameter
Example [I
assure long life to the dressing pin.
The diamond content of dressing pins made in accord
Small inaccuracies
ance with the present invention can vary over a sub
in machine set are corrected by running my pin through
stantial range. In the trade a diamond concentration
the centerless grinder as described.
of 100 denotes 72 carats by weight of diamond per cubic
While the embodiment of the present invention illus 20 inch of abrasive matrix. Thus the diamond concentra
trated in FIGURE 3 has been shown as having a uniform
diameter, it is to be considered within the scope of the
invention to fabricate the dressing pin in a stepped con
tion of the pins of the present invention can vary over
?guration for use in dressing wheels for the production
of infeed ?nished articles. In this method of operation, 25
the grinding wheel is dressed to stepped con?guration
and the work piece is fed into the wheel and then with
the range from 121/2 to 150. ‘This means that from about
17 carats per cubic inch to about 108 carats per cubic
inch of bonded matrix can be employed.
While I have described my invention in terms of the
presently’ preferred embodiments, it should be understood
that it may be otherwise embodied within the scope of
drawn, as contrasted to a through feed type of operation
the following claims.
where articles of uniform diameter are produced by feed
I claim:
ing the work piece into one side of the machine and out 30
l._In a method of dressing centerless grinders having
the other side. ‘
v
_
a grmding wheel, a regulating wheel, and a work rest,
The concept of the present invention is also applicable
to cylindrical grinders of the center-type. In these ma
the step of passing a cylindrical diamond dressing pin
between and in contact with the wheels in a path sub
chines the work piece, or the piece to be ground, is sup
ported between a pair of aligned centers and rotated.
While so supported, a rotating grinding wheel is engaged
with the surface of the work piece to effect a grinding
mg wheel while said wheels are rotating and while said
dressing pin is supported on said work rest.
operation thereon.
mg pin is of substantially the same diameter as the work
stantially parallel with the axis of rotation of said grind
_ 2. A method as set forth in claim 1 in which said dress
‘
As shown in FIGURE 4, a dressing pin made in accord~
ance with the present ‘invention is so fabricated as to be 10
a
supported by the centers of the grinding machine, as a
work piece would be supported. In this embodiment the
diamond dressing pin‘24 is of the same general structure
piece to be ground.
3. A method of dressing centerless grinders having a
grinding wheel, a regulating wheel, and a work rest which
comprises the steps of initially dressing the peripheral
surface of said grinding wheel, relatively adjusting the
axes of said grinding wheel and said regulating wheel so
as the pin 19 illustrated in FIGURE 3. Thus it com
prises a core 26 and an abrasive section, or shell 28 45 that» said axes lie in vertical planes that are substantially
parallel, and thereafter ?nally dressing the peripheral
therearound. However, the core is of elongated con
surfaces of both of said wheels while said wheels are ro—
?guration and extends beyond each end of the abrasive
tating by passing a cylindrical diamond dressing pin, sup
section 28. The core is suitably shaped at each end to
provide center holes 30, whereby the pin 24 can be sup 50 ported on said work rest, between and in contact with
said wheels in a path substantially parallel with the axis
ported between the centers (not shown) of a center-type
cylindrical grinding machine. The periphery of the
of said grinding wheel, whereby to eliminate irregularities
abrasive section 28 can be of greater or lesser width than
in the wheel surfaces and correct for small inaccuracies
of machine setting so that the wheels are in true alignment.
4. In a method of dressing centerless grinders having
a grinding wheel, a regulating wheel, and a work rest,
the grinding wheel to be dressed thereby. In FIGURE
4 the width of the grinding wheel 32 is illustrated as
being narrower than the abrasive section.
the steps of placing a cylindrical diamond dressing pin
The abrasive section 28 of the pin 24 is shown as being
between and in contact with said wheels while said wheels
substantially at the longitudinal center of the core 26.
are rotating and drawing said dressing pin through said
However, it is to be, considered within the scope of the
invention to place the abrasive section at any position 60 grinder by said regulating wheel in a path substantially
parallel with the axis of rotation of said grinding wheel
on the core. Also it is within the scope of the invention
while said dressing pin is supported on said work rest.
to form the abrasive section as a stepped con?guration
for dressing a grinding wheel of stepped con?guration.
References Cited in the ?le of this patent
UNITED STATES PATENTS
. The diameter of the pin of the present invention, as
applied to centerless grinding, will vary with the diameter
of the work piece.
Though they need not be exactly the same size as the
?nish dimension of the Work piece, this is an optimum
operation goal, as hereinbefore described. When ap
plied to center-type grinding, the diameter of the dress
ing'pin can be substantially greater or less than the di
meter of the work piece.
While, as described above, a steel core can be utilized
70
1,099,984
2,413,167
2,704,705
2,730,848
2,896,377
Kirsten _____________ __
Bugley _____________ __
Gifford _____________ __
Wallace ____________ __
June
Dec.
Mar.
Jan.
Walkling ____________ __ July
16,
24,
22,
17,
28,
1914
1946
1955
1956
1959
FOREIGN PATENTS
604,950
Great Britain ________ __ July 13, 1948
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