U.S. patent number 3,795,497 [Application Number 04/831,943] was granted by the patent office on 1974-03-05 for metal bonded grinding wheels.
Invention is credited to Shirley I. Weiss.
United States Patent |
3,795,497 |
Weiss |
March 5, 1974 |
METAL BONDED GRINDING WHEELS
Abstract
Grinding wheels having an electrodeposited metal matrix and
abrasive grit forming a grinding surface, with an electrodeposited
metal backing layer integrated with the composite matrix and grit
layer; the matrix layer having an optimized distribution of grit
therein.
Inventors: |
Weiss; Shirley I. (Ramsey,
NJ) |
Family
ID: |
25260258 |
Appl.
No.: |
04/831,943 |
Filed: |
June 10, 1969 |
Current U.S.
Class: |
51/297;
51/309 |
Current CPC
Class: |
B24D
18/0018 (20130101) |
Current International
Class: |
B24D
18/00 (20060101); B24d 003/06 () |
Field of
Search: |
;51/293,309,308,307,204,297 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Arnold; Donald J.
Attorney, Agent or Firm: Hilbert; Philip G.
Claims
1. A grinding member comprising a core element and an abrasive
layer on said core element, said abrasive layer comprising an
electrodeposited outer stratum consisting of a metallic matrix and
abrasive grit distributed through said matrix and an
electrodeposited inner stratum of metal integrally bonded to said
outer stratum, said matrix having a grit content of from about 40
percent to about 85 percent by volume, said abrasive layer being in
annular form and being in shrink fit relation to
2. A grinding member as in claim 1 wherein said matrix has a grit
content
3. A grinding member as in claim 1 wherein said grit is diamond
particles.
4. A grinding member as in claim 3 wherein the metal of said matrix
is selected from the group consisting of nickel, copper, silver,
nickel
5. A grinding member as in claim 1, wherein the grit in said outer
stratum comprises at least three superposed particles extending
through the
6. A grinding member as in claim 1, wherein said abrasive layer is
of
7. A grinding member as in claim 1 wherein, said outer stratum has
a radial thickness of from about 0.010 inch to about 0.250 inch,
and said inner stratum has a radial thickness of from about 0.050
inch to about 0.500
8. A method of forming a grinding layer for a grinding member
comprising providing a rotatable electrolytic cell including an
annular forming member as the cathode element thereof and an anode
element, with a metal plating solution containing a dispersion of
abrasive grit in said cell, continuously applying plating current
to said cathode and anode while rotating said cell during
successive spaced time intervals with intervening time intervals of
non-rotation to electrodeposit a metallic matrix carrying abrasive
grit on said forming member, the metallic matrix having a grit
content of from about 40 percent to about 85 percent by
9. A method as in claim 8, and thereafter continuously rotating
said cell to electrodeposite a metal backing layer in integrated
relation to said grit carrying matrix, and separating the backed
grit-carrying matrix from
10. A method as in claim 9, wherein said forming member is formed
of a low
11. A method as in claim 8, wherein the alternating rotational and
non-rotational time intervals are from 2 to 30 seconds and the
rotational speed is from 0.25 to 5.0 rpm.
Description
BACKGROUND OF THE INVENTION
Grinding wheels, cutoff wheels and forming wheels having a
grit-matrix grinding surface, have heretofore shown rather limited
useful life; being operable with a rather reduced load relative to
the materials being cut or ground; a tendency to rapid wear at the
edges of the device which necessitates repeated dressing of the
device; and having a limited cutting efficiency.
In known grinding wheel constructions of the sintered metal or
resinoid bonded types, the grit which is diamond particle or the
like, is generally limited to approximately 25 percent by volume of
the composite grit-matrix layer. Attempts to increase the grit
proportion with a corresponding decrease in matrix proportion, has
been directed to sintered metal bonded wheels. However, the reduced
matrix proportion leads to inefficient grit bonding and a resultant
reduction in the useful life of the wheel, as well as poor grinding
qualities.
Accordingly, an object of this invention is to provide improved
grinding wheels, cutoff wheels, forming wheels and the like; having
a grinding surface made up of grit such as diamond particles held
in an electroplated metal matrix; wherein the concentration of grit
is increased substantially and may be of the order of 75 percent to
85 percent of the total volume of the composite grit-matrix.
Another object of this invention is to provide improved grinding
wheels having a grinding surface made up of an electroplated metal
matrix holding a very large proportion of diamond particles; the
useful life of such improved grinding wheels being extended by as
much as 2 to 5 times that of known grinding wheels.
Yet another object of this invention is to provide grinding wheels
of the character described, wherein the total amount of grit
particles is distributed in an electroplated metal matrix of
reduced radial dimension to thereby substantially increase the
concentration of particles in the matrix, thereby allowing a
reduced amount of particles to be of increased effectiveness in use
and reducing the cost of the device.
Still another object of this invention is to provide improved
grinding wheels of the character described, wherein the
distribution and concentration of abrasive grit in an electroplated
metal matrix is of a character to substantially reduce wear at the
edges of the wheel and thereby reduce the need for dressing
operations during the useful life of the wheel.
Yet another object of this invention is to provide improved
grinding wheels of the character described, which are adapted to
withstand increased grinding loads when grinding or cutting very
hard materials, thus realizing relatively high rates of material
removal.
Other objects of this invention will in part be obvious and in part
hereinafter pointed out.
DESCRIPTION OF THE DRAWING
FIG. 1 is a transverse sectional view of a grinding wheel embodying
the invention;
FIG. 2 is a sectional view taken on the line 2--2 of FIG. 1;
FIG. 3 is a sectional view similar to that of FIG. 2, showing a
cutoff wheel embodying the invention;
FIG. 4 is a sectional view similar to that of FIG. 3, showing a
forming tool embodying the invention;
FIG. 5 is an elevational view in section showing apparatus for
forming the devices of the instant invention; and
FIG. 6 is a sectional view taken on the line 6--6 of FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIGS. 1, 2; 10 designates a grinding wheel embodying
the invention. The same comprises a metal core 11 which may be
formed of brass, aluminum, steel or the like. The core 11 has
affixed to the outer cylindrical surface thereof a grinding
assembly 12 which comprises an outer annular layer 13 and a backing
layer 14 integrated therewith.
The annular layer 13 is made up of an electroplated matrix of metal
or metal alloy carrying abrasive grit such as diamond particles or
the like. The grit content of the matrix is of the order of from
about 40 percent to about 85 percent by volume. The backing layer
14 is an electrodeposited layer of metal or metal alloy, preferably
similar to that of the matrix layer 13; the layers 13, 14 being in
integrated relation to each other.
Thus, the metal of layers 13, 14 may be of nickel, copper, silver;
nickel-cobalt; copper-nickel; copper-tin-nickel-cobalt, or other
suitable metals and metal alloys which lend themselves to
electrodeposition. The grit size can vary in accordance with the
desired grinding, cutting or forming characteristics of the wheel,
as related to the character and hardness of the material being
ground or cut; and may be in the range of from 1 micron to 1,200
microns. The radial thickness of layer 13 may be of the order of
from about 0.010 inch to about 0.250 inch, while the thickness of
layer 14 may range from about 0.050 inch to about 0.500 inch.
Alternatively, the invention may be embodied in a cutoff wheel 10A,
shown in FIG. 3, wherein a metal core 11A carries the grinding
assembly 12A, made up of a composite metal matrix and grit layer
13A and a backing layer of electrodeposited metal 14A, as
previously described.
Also, as shown in FIG. 4, the invention is embodied in a forming
wheel or tool 10B, with a core 11B carrying the grinding assembly
12B made up of composit grit-matrix layer 13B and backing layer
14B. Here the grinding layer 13B is contoured to a selected cross
section corresponding to the section of the work piece to be ground
and formed.
The assembly 12, 12A or 12B is formed in apparatus shown in FIG. 5
and generally indicated at 15. Such apparatus comprises a pair of
circular disc members 16, 17 formed of methyl methacrylate or other
suitable synthetic resin. Disc 16 is formed on one surface thereof
with an annular shallow recess 18, providing a shoulder 19. Disc 17
is formed on one surface thereof with a small diameter recess 20
and a concentric larger diameter recess 21; an annular juncture
portion 22 of conical shape; and providing an annular shoulder
23.
The discs 16, 17 are held in axially opposed relation, with
recesses 18, 20 thereof facing each other; by a series of
circumferentially spaced bolts 24 passing through aligned openings
in the peripheral portions 25, 26 respectively of said discs 16,
17.
A tubular member 27 of a diameter to fit the same snugly in
shoulders 19, 23 of discs 16, 17, is disposed between said discs to
form a rotatable plating chamber. Member 27 has an axial extent
equal to the axial extent of grinding wheel 10 to be formed. An
annular layer 28 of a low melting point alloy such as lead-tin or
the like, is cast on the inner surface of member 27 and its annular
inner surface 29 is precision machined to a given inner
diamater.
A tubular anode 30 is axially mounted on disc 16 by way of a rod 31
and a nut 32 on its threaded inner end. The outer end portion of
rod 31 passes through an axial opening 33 in disc 16 and terminates
in a socketed coupling head portion 34. A cathode connector 35
having a threaded portion 36 is screwed into the outer portion of
disc 16 to make electrical contact with member 27 and layer 28.
A filler opening 37 is formed in disc 17, being closed by a
threaded plug 38, to allow the plating chamber 40 formed by
assembled discs 16, 17 and member 27, to receive a plating solution
PS to a level above the anode 30. The solution PS typically may be
of a nickel salt such as nickel sulfamate or the like, in which
case the anode 30 is also of nickel.
The solution PS also contains a calculated quantity of diamond or
other abrasive grit of selected size. The apparatus 15 is arranged
for rotation about its horizontal axis, by suitable motor means,
not shown, through coupling head 34. Leads from a suitable plating
current source are connected to cathode connector 35 and anode rod
31, in a manner known in the art. The current source has a voltage
of from 2 to 6 volts and an amperage of the order of from 5 to 30
amperes per sq. ft.
The apparatus 15 is operated in two successive phases. Initially,
the device is alternatively rotated at a given constant speed and
stopped; with the rotational periods ranging from 2 to 30 seconds
and the rest periods ranging from 2 to 30 seconds. The rotational
speed is of the order of from about 0.25 to 5.0 rpm.
During such initial phase of operation, the composite layer 13 made
up of metal or metal alloy and grit is electrodeposited on the
inner surface 29 of annular layer 28. Upon exhausting the diamond
grit content of solution PS, the layer 13 is completed to a
selected radial dimension. Such layer 13 may have a grit content of
up to 75 percent to 85 percent by volume. Reduced volumetric
proportions of grit, to values of about 40 percent by volume may be
attained by suitable adjustment of the rotational and rest periods
of the initial phase of operation of apparatus 15.
The apparatus 15 is then operated in its second phase, by rotating
the device continuously at a rate of from about 0.25 to about 5.0
rpm, to form the backing layer 14 of metal or metal alloy in
integrated relation to layer 13. The radial thickness of layer 14
may vary from 0.050 inch to 0.500 inch; and may be suitably related
to the radial thickness of layer 13.
The apparatus 15 is provided with a breather assembly 41 mounted on
disc 17; the same comprising a nipple 42 with an upstanding
breather tube 42A; the nipple 42 passing through an opening 43 in
disc 17 with a packing 44 and gland nut 45 sealing the same. A stem
46 extending from an outer portion of nipple 42 anchoring the same
as at 47 to maintain tube 42A in its upright position while the
apparatus rotates. Thus, gases discharged in chamber 40 during the
electrodeposition operation, may be evacuated by way of breather
tube 42A and nipple 42.
When the electrodeposition operations have been completed, the
remaining solution PS is drained by way of opening 37 and the discs
16, 17 are disassembled from the member 27. The member 27 is then
subjected to a temperature sufficient to melt layer 28, permitting
the assembly 12 to be separated from member 27.
The composite 13, 14 of assembly 12 is now ready to be mounted on
core 11. To this end, the I.D. of assembly 12 is machined to a
given value and the O.D. of core 11 is machined to a value slightly
greater than that of the I.D. of assembly 12. The core 11 is then
cooled by dry ice, liquid nitrogen, or the like to temporarily
reduce the O.D. to a value slightly less then the I.D. of assembly
12, allowing insertion of core 11 in assembly 12. On regaining room
temperature, the core 11 is in a gripping relation to assembly 12,
to form the finished grinding wheel 10.
It will be apparent that assembly 12 may be secured in mounted
relation to core 11, as by soldering or brazing; or by an
interlayer of epoxy resin adhesive.
It is understood that member 27 is replaced by other members when
forming the cutoff wheel 10A, in which case member 27 has a small
axial extent of the order of the thickness of core 11A. Also, the
member 27 may be profiled at its periphery to provide an
appropriate transverse contour in deposited layer 28, which in turn
produces the composite 13B, 14B, FIG. 4, of corresponding contour
to form with core 11B, forming tool 10B.
It will be apparent that plating solution PS is made up in a known
manner, to include salts corresponding to the metal or alloy to be
deposited to form the matrix carrying the abrasive grit.
It has been found that the procedure hereinbefore disclosed, allows
for the layer 13 of the grinding assembly 12 to be made up of
superposed diamond or other abrasive particles with interposed
metal matrix material. Thus, the radial dimension of layer 13 is
dependent on the number of superposed particles, particle size and
proportion of metal matrix.
* * * * *