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Патент USA US2404192

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July 16, 1946.
K. G. RlEs ET AL
' 2,404,192
Filed DGO. 29, 1944
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Patented July 16, 1946
_UNITED `s'rrrl‘iëz-s `PATENT OFFICE*
Kernell G. Ries, Niagara Falls, Norman I’. Robie,
Lewiston, and Phyllis von D'oenhoff, Niagara
Falls, N. Y., assignors to The Carborundum
Company, Niagara Falls, N. Y., a corporation of
ApplicationDecember 2 9, i944,seria1No. 570,314
This invention relates tothe lmanufacture of
It has, therefore, long been desirable to iind
abrasive articles. More particularly, it relates to
the manufacture of composite abrasive articles
some other more advantageous way of making
vsuch articles. Previous attempts to form the
comprising two or more resin bonded bodies con
aforesaid articles from liquid mixtures of bond
taining iillers, at least one of which is abrasive in
character and capable of use for abrading pur
poses, the individual filler-containing resin bodies
being integrally united to form the composite
article. The invention also pertains to methods
of using liquid or «casting resins as bonds in the 10
and abrasive or other iiller materials have not
mety with complete success due to the inability to
obtain a satisfactorily strong union between the
constituent'parts of the article and at the same
time prevent an undesirable mixingor intermin
manufacture of such articles in which the con
stituent bonded bodies of~ the >article >are inte
fillers employed in making the article.
satisfactory results that such combination sharp
tions. The porous diaphragm allows the liquid,
unpolymerized bond to pass through and join-the
gling of the various abrasive and/ or non-abrasive
It is an object of the present invention to >pro
vide such composite abrasive articles having an
grally combined, but with the ñllers of those
improved uniformity and structure.. It is a fur
constituents sharply segregated one from another.
The present invention is especially adap-table 15 ther object to provide improved methods of man
ufacturing such articles which will avoid the dis
for making dense, ñne grit abrasive articles, as
advantages and undesirable features of prior art
for example, the making of dual-purpose or com
methods as above set forth.
bination honing stones embodying in the one
We have found that composite abrasive articles
article a resin bonded abrasive body containing
a relatively _coarse grit size abrasive ñller for 20 can be made with a plurality of casting composi
tions in one article Withoutintermixing ofthe
rough grinding and a resin bonded abrasive body
powdered ñller materials contained in those cast
containing an abrasive filler of much liner par~
ing compositions by the use of .a porous diaphragm
ticle size for ñnishing grindingor ñnal sharpen
inserted between the different casting composi
ing operations. It is highly desirable for most
ening stones or hones be as dense and uniform
as possible in order to avoid uneven or irregular
mixes into a unitary article without permitting
cutting action on the instrument being sharpened
the intermixing of the various ñller materials.
According to the present invention, composite
and also that the different size abrasive particles
employed in making the article be kept from in-` 30 abrasive articlesof the type described above are
made by first formingv a suitable mixture of a
termingling one with the other. Heretofore such
liquid or casting resin together with the selected
combination sharpening stones have been formed
by pressure molding relatively dry but ldampened
iìller or fillers for forming one part of the article
mixtures of the abrasive powder and powdered
and placing a sufficient amount of the mixture
resin in a hot mold, followed by a prolonged oven 35 in a mold of the desired shape to form that part
cure. When prepared according to such pro
of the article when set, after which a thin layer
cedures, the aggregation of the resin powder into
of porous sheet materiaLisuch as -a sheet of coarse
larger particles has prevented a thorough wetting
filter paper, is placed in the mold over the con
and dispersing of the iinely divided abrasive ma
Y tents of liquid resin and nller as a diaphragm.
terial, and, as a result, the articles so made have 40 A mixture of liquid resin and ñller which is to
not been as uniform as could be desired. The
constitute the second part of the composite article
formation of such articles by pressing methods
is then prepared and poured into the mold on top
hasalso required the use of costly molds and
of the thin sheet of porous material and the entire
mold contents are allowed to harden orl set after
presses, and required long, high temperaturecures.
portion, as for example, the making of a resin
which the molded shape is removed from the
mold, Vand when desired, given a suitable oven
cure'. Other porous materials can be used as the
intercalary diaphragm in place of the iilter paper
between the constituent resin-ñller mixes so long
as the material chosen is permeable to the resin
bond and impervious to the different granula
bonded grinding wheel having the abrasiveV par
ticles confined to that part of thewheel in the
The employed
liquid resin
in bond
forming thev two
vicinity of one or both i‘lat faces or extending
radially inward but a short distance from the
periphery of the wheel. As in the making of the
different parts of the article is usually the same
although different resins can be used to form the
Certain of the above disadvantages havel also
been encountered in the making of composite
abrasive articles embodying a resin bonded abra
sive 'grinding surface integrally combined with a
non-abrasive resin bonded supporting or body
various `parts of the article, providing they are
combination sharpening stones mentioned above,
the manufacture of such articles by pressing pro
cedures entails the use of expensive equipment
and“ lengthy processes.
compatible and are capable of penetrating the
porous intercalary sheet material. In the article
so formed, it will also be found that if the proper
-materials are selected, the granular ñllers con
tained in the various parts of the article Will not
mixture into-the mold.. >This can be accomplished
pass through the porous Vsheet material; so that
more easily by forming the article in molds such
` there will be a sharp, clear dividing line betweenv
ras those shown in Figures 2 and 3, which are
the component parts of the resulting abrasive '
article _with no intermingling of the different ñller '
usually of suitable metallic construction with the
exception ofthe diaphragm which is usually aV
porous ñbrous sheet material.
A modified method of makingabrasive articles Y
Y embodying the principle of the present invention,
The mold con
struction depicted in Figure 2 consists of a lower
mold half I4 and an upper mold half I5 which
' anda method which is particularly adaptable' to Y
fits tightly over the lower half I4, holding the
forming abrasive articles of the type wherein'the 10 porous diaphragm I 6 in place. The slight out
` » .
abrasiveis conñned to a relatively small portion
of the'article in the immediate-vicinity of the
grinding surface, can -be carried out asA follows.
The porous diaphragm or separating medium,
such as a layer of ñlter paper, is first coated on
one side with a mixture of liquid or casting resin
ward iiare I1 of the upper mold half assists in
quickly placin-g the upper half in position on the
lower half. In use', the lower mold'half I 4 is i'llled
with the first liquid, filler-containing Vmixture
15 and the sheet I6 of porous material constituting
and abrasive particles, either by first applyinga
the diaphragm Vis placed upon the top of the
Vfreshly poured contents and held tightly in place
coating of the resin to the .filter paper and then
while the upper half of 'the mold is placed in
addingtheabrasive particles to the adhesively
position, thereby holding »the diaphragm ñrmly
coated surface or mixing the abrasive particles 20 and accurately in place. The second liquidv mix
with the liquid resin and applying the mixture to
ture'containing a diiîerent ñlleris then poured
the Vi‘llter paper or other porous sheet material.
on top of the diaphragm to ñll the upper half of
The thus coated filter paper is then suitably
the mold. Themold contents are then allowed
placed in a mold with the resin and abrasive coat
to set, removed from the mold and usually given
ed side facing the inner mold surfaces and the 25 an oven cure to mature the resin bond. If de
mold ñlled with the liquid resin mixture, usually
sired, the mold contents can be subjected to a
containing a non-abrasive filler, `which is to con
heat treatment at low temperature to hasten set
stitute the body of the article, and the mold con
tents allowed to set or harden, after which the
ting of the resin bond..
strongly combine the abrasivecontaining portion
the porous diaphragm 22 tightly in position. The
clamps 23 serve to draw the mold lips tightly
The mold in Figure 3, like that in Figure 2, con
article so formed is removed from the mold and 30 sists of a lower moldhalf I8 and an upper mold
usually‘given'an oven cure. « Again, thevabrasive
half I9 and is used similarly. The two mold con-_
e particles will be preserved in position at and ad
structions differ fin the Vmanner of holding the
jacent to the grinding surface ofthe resulting
porous diaphragm in place.? In Figure 3 the upper
' ' article whereas the penetration of the resin bond
and lower mold halves I8 and I9 are equipped
therefor through the. porous sheet serves to 35 with side lips 20 and 2| which ñt together to hold
to the main body of the article with no danger
of delamination~
In order to better understand the nature of the
Figure 4 Ais a side view of a modified abrasive
invention, reference is made to the accompanying 40 sharpening stone 24 similar in'shape and con-V
drawing, in which: ,
struction to that depicted in Figure 1 but diñ‘er
Figure 1 is a side view of a combination abra
ing therefrom in the composition of the two
sive sharpening stone made in accordance with
bodies 25 and 26 which make up the article.’ The
the present invention;
abrasive article shown in Figure 4 is composed
Figure 2 is a vertical cross-sectional view illus
of a resin-bonded, ,Áñne grit size abrasive body 25
f trating one form of .mold set-up used in
out the present invention; and
, and a resinous non-abrasive body 26, the two
bodies 25 and 26 being separated in a sharp line
Figure 3 is a vertical cross-sectional view illus
of Vdemarcation between them by reason of the
trating a modified form of mold set-up which can
presence between the twol bodies of a thin sheet
be used in connection With the present invention. 50 of porous filter paper 9 which is permeable to theY `
Figure 4 is aside View of a modiñed form of
resin bond I0 but is impervious to the i’ine abra
abrasive sharpening` stoneY made in accordance
siveparticles I 2 of the resin bonded abrasive body
with the present invention.
25 and also impervious to any non-abrasive ñller
Referring further'to the drawing, Figure 1 is a
substances whichV may be incorporated, when de
sidefview oi"v aY combination sharpening stone 6 55 sired, in the non-abrasive resinous body 26.’
composed of a coarse grit size abrasive body 'I
The following example is given as illustrative.
and a iine grit size abrasive body `8, the abrasive
A combination abrasive hone, such as that
fillers of the two bonded abrasive bodies 'I and
shown in Figure 1, was _made having one face
8Vbein~g separated in a sharp line of demarcation
suitable for preliminary honing comprising resin
between them by reason of the presence between ï
bonded 320 mesh size, silicon carbide andthe op- l
the two bonded bodies of a, thin sheet of porous '
posite face suitable for finish honing and coml
filter paper 9 which'is permeable to the resin bond
prising resin bonded, 600 mesh and finer fused
I0 but is impervious to either the coarse abrasive
alumina. The same bond was used throughout.
particles I_ I of the bonded body 'I or the ñne abra
The mixture for the bottom layerwas composedr
` ¿E sive particles I2 of the resin bonded bodyV 8.
of 26% allyl resin monomer (suchas that known
The composite sharpening stone shown in Fig'- V` and sold by the Columbia Chemicals Division of
Pittsburgh Plate Glass Co. as CR-39 resin mono
ure 1 can be formedin the usual type of mold by
partially ?illingthe mold with the ñrst pourable,
mer) and 74%V 320 mesh silicon carbide and con
liquid resin mixture, inserting the porous sheet
taining dissolved iny the monomer benzoyl per
material on top of the mold contents by hand, 19 oxide catalyst to the extent of 3% of the mono
and ñlling the balance of the mold with the sec
mer. This liquid mixture was poured into a=rec-`
Vond desired mixture. However,4 it is desirable to '
tangular mold such as that shown in Figure 2.
hold the porous diaphragm tightly in position in
A sheet of _very porous ñlter paper was then laid
order to prevent wrinkling or dislocation of the
upon the freshly poured mix. A second casting-
sheetmaterial during the pouring of the second 76 mixture was poured onto the filter paper to fill
the mold. This second casting mixture consisted
characteristic abrasive material of each abrading
body of the article being separated from the abra
sive material c-f the adjoining'abrading body by
of 30%' of allyl resin monomer known as CR-39
monomer, 70% very fine fused alumina, polishing
Ipowder having a particle size of 600 mesh and
nner and 3% benzoyl peroxide based on the
The mold contents were allowed to
solidify after which the cast article was removed
from the mold and the resin bond cured at 150°
F, for 18 hours, then raised 15 degrees per hour
for two hours, 10 degrees per hour for two hours,
and finally held one hour at 200° F. The cured
hone was surfaced on a rotating metal lapping
a thin layer of sheet material permeable to the
resin bonds but impervious to the abrasive ma»
terials of said article.
2. v.A resin bonded composite abrasive article
having at least two dissimilar abrading bodies
integrally united by means of a resin bond com-A
mon to the constituent bodies thereof, the char
acteristic abrasive material of each labrading
body of the article being separated from the
disc charged with abrasive andwater, The fin
abrasive material of the adjoining abrading body
ished article was extremely uniform and of high
density with a sharp line of demarcation between
by a thin layer of sheet material permeable to
the resin bond but impervious to the abrasive ma
,the different bonded abrasive bodies thereof.
The resin bond thoroughly penetrated through
and hardened in the ñlter paper so that there
was no sign of delamination or weakness in the
terials of said article.
3. A resin bonded abrasive article comprising
a surface portion of resin bonded abrasive ma
terial integrally united to a resinous body portion
line of union between the different bonded parts
through an intercalary fibrous sheet material im
of the article.
pervious to the abrasive particles of said surface
The bonds which may be >used to make cast
portion but permeated by the resin bond.
articles accordingto the practices of the present
4. A resin bonded abrasive article comprising
invention include those resins produced from un
a body of resin bonded abrasive material integral
saturated monomers by addition polymerization. 25 ly united to a non-abrasive resinous body through
'I‘ypical monomers are the vinyl, acrylic and allyl
an intercalary fibrous shëet material inpervious
monomers, such as diallyl phthalate, diallyl
to the abrasive particles of the abrasive body but
maleate, diallyl fumarate, methyl-methacrylate,
permeated by the resin bond of the article.
vinyl acetate, styrene, diallyl diethylene glycol
5. A method of making bonded abrasive articles
carbonate, and the like. Mixtures of monomers . which comprises preparing amixture comprising
to produce copolymers and cross linked resins may
a liquid resin and an abrasive filler, pouring said
also be used. We may also’use solutions -of re~
mixture into a suitable mold, placing a thin sheet
active resins in monomers such as a solution of
of ñbrous material permeable to the liquid resin
an unsaturated alkyd ofthe glycol~maleic anhy
but impervious to the abrasive filler of the afore
dride type in diallyl phthalate or styrene mono- i said mixture over ethe top surface of the mixture
mer. It is also possible to use certain initial con
contained in said mold, preparing a second mix
densation polymers in liquid form, such as heat
ture comprising a liquid resin and an abrasive
hardenable, liquid urea or phenolic casting resins.
filler differing from the filler of the ñrst mixture,
In practicing the invention any of the abrasive
pouring the second mixture into the aforesaid
materials in common use may be employed such 40 mold on top of said sheet material, allowing the
as silicon carbide, diamonds, boron carbide, fused
mold contents to set and removing them from
aluminum oxide, nint, corundum,`emery, rouge,
the mold.
and similar substances. The size of the abrasive
6. A method of making bonded abrasive articles
particles may vary from the finest polishing or
which comprises preparing a mixture comprising
buiflng powder to the coarser grit sizes used in 45 a casting resin and an abrasive filler, pouring
grinding. When composite abrasive articles are
said mixture into a suitable mold, placing a thin
being formed wherein one of the resin bonded
sheet of porous material permeable to the casting
bodies constituting the entire article is non
resin but impervious to the abrasive filler of the
abrasive in character any organic or inorganic
aforesaid mixture over the top surface of the mix
non-abrasive fillersA may be incorporated in the 50 ture contained in said mold, preparing a second
resin bond thereof, such as carbon black, clays,
mixture comprising a casting resin and an abra
wood flours, mineral fillers and the like.
sive filler diifering from the filler of the first
The present invention is very adaptable to
mixture, pouring the second mixture into the
making composite abrasive articles which employ
aforesaid mold on top of said sheet material,
a relatively finely divided abrasive material and 55 allowing the mold contents to set and removing
dense bond in one or more of the sections mak
them from the mold.
ing up the article, such as the combination hone
7. A method of making bonded abrasive articles
previously illustrated. The shape of the sec
which comprises preparing a mixture comprising l
tions making up the article may vary and may
a liquid resin and an abrasive filler, pouring said
consist of cylinders, rods, sections of a circle and
mixture into a suitable mold, placing a thin sheet
other shapes as well as layers. Other composite
of fibrous material permeable to the liquid resin
articles which can be made include mounted hon
but impervious to the abrasive ñller of the afore
ing wheels, diamond wheels, discs for lapping
said mixture over the top surface of the mixture
machines, die honing sticks, polishing discs,
contained in said mold, preparing a second mix
thread grinding wheels, and so forth.
ture comprising a liquid resin and a non-abra
Having described and set forth the invention
sive ñller, pouring the second mixture into the
in detail, the scope of the invention is not to be
aforesaid mold on top of said sheet material,
confined other than by the appended claims.
allowing -the mold contents to set and removing
We claim:
them from the mold.
1. A resin bonded composite abrasive article
having at least ftwo dissimilar abrading bodies
Áintegrally united by means of compatible resin
bonds of the lconstituent abrasive bodies, the
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