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Патент USA US2119412

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May 31, 1938.
Filed Dec. .30, 1935
2 Sheets-‘Sheet 1
o c.a
May 31, 1938. 1
Filed Dec. :50, 1935
2~Sheets-Sheet 2
Patented May 31, 1938
PATENT- oer-"Ice
Albert L. Ball, Lewiston Heights, and Raymond C.
Benner, Niagara Falls, N. Y., assignors, by
inesne assignments, to The Carborundum Com
pany, Niagara Falls, N. Y., a corporation of
Delaware ,
Application December 30, 1935, Serial No. 56,709
13 Claims.
(Cl. 51-206)
This invention relates to segmental abrasive. water.
wheels and relates more particularly to means for
securing a plurality of wheel segments on a rotat
able hub or drum.
, It has become customary to make large wheels
as well as many intermediate sizes by building
them up from a number of segments because of
the difficulties involved in manufacturing and
using unitary abrasive wheels which are several
feet in diameter and which are composed of
arti?cially bonded abrasive. Somewhat smaller
segmental wheels are also desirable in certain
cases, the wheels for grinding pearl buttons be
ing one example, where operating conditions are
15 such that a non-uniform thermal condition is
' brought about by excessive heating of the wheel
periphery. The monolithic or continuous ring
type of structure is easily cracked by such condi
tions whereas the segmental vwheel is not, the
20 smaller abrasive units being capable of resisting
these temperature differences. Some of these
dimculties are found in the attempts to uniform
ly compact, dry and handle abrasive masses
A ceramically bonded abrasive segment
has in general, however, a lower coe?icient of
thermal expansion than that of the metal sup
ports for the segments and a coefficient of ex
pansion which is less than that of the steel driv- ‘
ing shaft. Such differences in thermal expansion
have to be considered in view of the variations in
temperature to which a wheel is subjected. when
shipped to a cold‘ climate, the temperature of a
wheel may be as low as -40° Fahrenheit in
transit. In the course of operation the wheel
may be subjected to temperatures approaching
the boiling point of water, that is temperatures
more than two hundred degrees higher than pos
sible transit temperatures when the wheel is 18
shipped to a cold climate. Abrasive segments
that have been bonded with a synthetic resin have
in general a higher coe?icient of thermal expan
sion than vitri?ed abrasive segments. Moreover
synthetic resins are usually cured at temperatures
not exceeding about 300° Fahrenheit.
After the abrasive segments have been made,
also in uniformly heating and cooling ceramic
their mounting on a rotatable support presents
serious difficulties, the overcoming of which con
stitutes the objects of this invention, such as:
1. The assembly of a large number of segments
masses of these sizes without breakage; the
on a rotatable support in one operation. This is
which may be six feet in diameter and one foot
25 thick such as the wheels used in grinding cutlery,
monetary loss occasioned by the breakage of one
mass weighing several tons is extreme compared
30 to nearly zero loss when manufacturing the same
total mass in the form‘ of small units such as seg
desirable from the points of view of accurate
spacing of the segments and economy of time.
2. The seating of the segments on the support 30
and uniting them to the support and to each other
in such a manner as to give a substantially solid,
balanced wheel.
' 3. The simultaneous attachment of the abrasive
articles made with vitri?able bonds are usually
segments to the rotatable support and to each‘ 35
35 employed. The vitri?cation temperatures em
ployed-in this art are usually at least 1000" C. other including the formation of perfect seating
and generally as high as 1300° C. The uniform ‘ means for the segments against the support.
4. .Provision for easy removal of an injured seg-7 _
heating and cooling of an abrasive segment whose‘
ment and replacement with a new segment.
dhnensionsrare. much smaller than the dimen
For a number of reasons bonded abrasive
According to the present invention, the abrae
complishithan the uniform heating and cooling ' I sive segments are each formed with one or more '
grooves in the faces which are to be placed ad"-' "'
of an: abrasiveiting'a‘.
‘wheel combination
large number
of such
has been
seg- f, jacent the rotatable support, that is in the__'i_5aces '
‘which are opposite to the working surfaces Eif'the
‘adapted to be combined into , segm'ents. Corresponding grooves are for'n'i'ed‘mt
wheelv can be, made from—'abrasive the adjacent portions of the rotatable support
mixes-“containing!?nely‘ divided silicon carbide which may be in'the form of an‘ annular: 111i“
or fused alumina‘, the abrasive grain being bonded; drum. "The grooves maybe formed in "‘th
by meansofia- ceramic bond or_~by means of a ,._ments during the moldingfproces‘s and i_
40 sions of;a completed wheel ‘is much easier to ac-~ '
heat‘hardenablesynthetic resin.v _A ceramic bond
during the casting process. 'Thevgroov‘esi
whichv is cured-by ‘being heated to .a vitrifying of thesebodies may have a
temperature and.vv which is carefully cooled ‘
through the ‘criticalannealing range hasiadvam'
tages for .use. in; wet v grinding from the ’ point of
55 view of resistance to ‘the, disintegrating action of
ways will be referred to generally as dovetail
grooves. The direction of the grooves described
above may be parallel to the axis of rotation of
the wheel or they may be inclined at an angle
thereto. In the assembly of the parts, the an
nularhub is laid on a horizontal base with its
axis vertical, and the abrasive segments are
placed in position on the base in an annular for
mation with the dovetailgrooves mentioned above
10 opposite to the corresponding grooves in the hub
of‘ drum.
The dovetail grooves are then ?lled
simultaneously with a hardenable synthetic resin
in liquid or plastic form such as a thermally re
versible resin, or are filled with metal. The gaps
15 between the segments and the gaps between the
segments and the supporting hub may be ?lled
with the same hardenable synthetic resin that
vis used to ?ll the grooves in one modi?cation 'of
the wheel structure disclosed below.
20 materials or metals may also be used between the
placed that the dovetail grooves ‘I in each seg
ment come directly opposite to corresponding
dovetail grooves 9 in the hub. The cap II of the
mold is then put on the barrel of the mold. A
cylindrical plunger 5 is inserted through a cen
tral opening in the base of the mold 6. The
diameter of the plunger 5 is such ‘that it ?ts
snugly within the hub 4. The upper surface of
the plunger 5 lies below the central horizontal
plane I—I of the'mold. Thermoplastic material 10
I2 (e. g. in granular or powdered form) is placed
above the plunger 5 in su?icient amount to ?ll. ,
the grooves ‘I and 9 as well as the gaps between
adjacent segments and the gap between the seg
ments and the hub as a result of the pressure to 15
be exerted on the plastic material. A second
plunger I0 is placed on top of the thermoplastic
material and the mold is mounted between the
platens of‘ a hot press such as is used in plastic
molding. The plastic material can be, for ex 20
ample, made from a polymerized vinyl acetate
segments or between the segments and the hub.
The methods of assembly of the segments on 'resin in which part of the acetate groups have
the hub which have been brie?y referred to above been replaced by acetaldehyde or by formalde
are illustrated by means of the accompanying hyde, such as can be obtained under the trade
25 drawings in which:
name “Alvar" 15-—70 or “Formvar” 4146. The
Fig. 1 shows a horizontal section of the seg
“Alvar” resin is made from a vinyl acetate resin
which has been polymerized to such an extent
ments of a wheel assembled around a hub and
within the barrel of a mold, the section'being that its molar solution in benzol has a viscosity of
taken on the line I—I of Fig. 2;
15 centipoises at 20° C. and in which 70 per cent
Fig. 2 is a vertical section of. the arrangement ’ of the acetate groups have been replaced by acet 30
shown in Fig. 1, the section being taken on two ' aldehyde. The “Formvar” resin is made from a
vinyl acetate resin in which part of the acetate
vertical planes which intersect in the axis of the
groups have been replaced by formaldehyde. It
wheel as indicated by the line II--II of Fig. 1;
Fig. 3 is va vertical section of the mold and‘ is not intended that the invention be limited to
article taken in the vertical planes used in Fig. 2, this particular material; many others can be used. 35
but indicating a metal ?lling in the grooves and There are also phenol formaldehyde types of resin
which will serve the purpose.
Fig. 4 is a fragmentary section in a plane per
Plastic material of the type which has just
pendicular to the axis of an abrasive wheel made been described (preferably in granular or pow
40 in accordance with the present invention, the
dered form) is indicated in Fig. 2 as occupying
scale being enlarged as compared with Fig. 1 and at vthe beginning of the operation of the press
the character of the material used for joining the [the space between the two plungers 5 and I 0.
segments to each other and to the hub being of a During the operation of the heated press the plas
similar character to that indicated for ?lling the tic material is forced through‘ the holes l3 into the
grooves 9 and ‘I and thence into the gaps between
45 dovetail grooves in Fig. 1;
Fig. 5 is a view similar to that shown in Fig. 4 the segments I and into the gap between the seg
but indicating a modi?cation of the materials ments and the hub or drum 4. The mold and its
used in the dovetail grooves and in the various contents are then cooled until the material thus
pressed into the cavities of the abrasive wheel has
Fig. 6 is a view similar to that shown in Fig. hardened, forming a substantially rigid segmen
4, but indicating the use of metal in the grooves tal wheel.
and joints; and
In the arrangement for the assembly of the
Figure '7 is a fragmentary view taken. in an abrasive segments illustrated in Fig. 3 the holes
I3 in the hub 4 are omitted. The procedure is
axial plane and illustrating the construction of
55 a composite key which is used to connect an different in some respects from the procedure
abrasive segment and the_adjacent portion of the
just described since the keyways (formed by the
supporting drum.
pairs of dovetail grooves ‘I and 9) and the various
gaps betweenthe members ofthe wheel are to
Referring to'the drawings in detail abrasive
segments I are assembled on the base of a mold
be ?lled with metal by pouring in molten metal.‘
6 with the outer surfaces of the segments abut
ting the inner surface of a mold barrel 2. The
barrel 2 is attached to the base of the mold 6 by
In practicing this modi?cation of the invention 1
the abrasive’segrnents I are arranged about the -.
means of screws as indicated in Fig. 2 of the
drawings. A hub or drum 4 is placed inside the '
abrasive- segments. The segments, the barrel,
and the hub are so proportioned that spaces 3
are left between the segments when they are
assembled and an annular space is left between
the hub and the inner faces of the segments.
Spacing strips can be used to aid the workman
in making the gaps 3 between the segments of
the same thickness for each pair of adjacent seg
ments. Spacers may also be used to obtain a
inside of the barrel 2 and on the base 6 as before,
and the hub 4 is centered with reference to the
base 8 and the barrel 2. The assembly of the
segments I and of the members 2, 6 and 4 is then
heated to about 100° C., after which metal which
has been heated to about 100 centigrade degrees
above its melting point is_ poured into the keyways
uniform gap between the hub and the inner faces
formed by the pairs of dovetail grooves ‘I and 9
and into the gaps between the adjacent segments 70
as well as the gap between the hub 4 and the seg
While the molten material is being
cast into place the entire assembly is jolted or
jarred several times by lifting it an inch or two
of the segments.
and allowing it to drop; or by striking suitable ~75
The segments are also so
3 ,
blows with a hammer or sledge. After ‘cooling
the wheel is removed from 1 the oven and is ‘fin
These constituents are mixed with about eight
ished by using methods similar to those employed‘
The abrasive surfaces to be joined are primed
with suspension made as just described and the
benzol allowed to evaporate. Where a joint
thickness of 3/32 inch is contemplated for the
?nished wheel, rubber sheets having a thickness
of about tin" and having the constituents of
Formula A are prepared. These sheets are cut
to size and applied to the primed faces of the 10
segments. The hub or rotatable support for the
segments is laid on a base plate with the axis of
in the case of other abrasive wheels.
The material which is poured into the keyways
and gaps may be a low melting-point alloy re
sembling Babbitt metal in its general properties.
The alloy should be mechanically strong at the
temperatures of wheel operation, but should be
10 capable of yielding slightly under large pressures
caused by temperature changes in the wheel.
Metals of the following compositions have been
times their weight of benzol.
the hub in a vertical position, a mat of sponge
rubber about 1A" thick being interposed between
the hub and the base plate as a sealing means 15
between the two'. ‘A rubber suspension (made
Tellurium ____________________________ __: _'_
0. 5
Fig. 5 illustrates a form of abrasive wheel of
‘the same general type as that shown in Fig. '4.
20 The oppositely disposed grooves ‘I and 9 (in the
abrasive segments and in the hub respectively)
are, however, ?lled with metal, while resilient
joints are provided between the, abrasive seg
ments and between the segments and the sup
In view of the somewhat more
complex character of the mounting in this form‘
of segmental abrasive wheel, a more detailed
description is given as an example of a method:
of assembly of the abrasive segments and of the
25 porting hub.
30 manner in which they are joined to each other
and to the supporting hub.
' 7
Before the segments are brought together,
sheets of vulcanizable material are made with
the ingredients given in Formula A below.
Formula A
Percentage of
by Weight
Smoked sheet rubber _______________________ __
Plasticizer and accelerat
61. 5
Ammonium carbonate__
4. 3
Sulphur ______________ __
6. 2
This composition gives a porous elastic hard
rubber on heating to a suitable vulcanization
temperature; it is capable‘ of being deformed
under pressure such as might result from cool
ing the assembled wheel and of expanding to
50 ?ll the joint space upon release of pressure.
The faces of the segments’ which are to bev
joined are primed as a preliminary stepv with a
rubber suspension of the type indicated in For
mula B. The priming serves to ?ll the pore
7' spaces in the abrasive and to reinforce the sur
face against break-down when the abrasive wheel
is trued or sharpened. It is customary when
using abrasive for certain classes of grinding,
etc. to cut a pattern on the working face. This
60 is done with a burring tool which may be pro
vided with either narrow steel cutting edges or
steel points; in some instances the wheel face
is simply hacked with a steel tool. It is obvious
therefore that abrasive corners at joints must be
65 reinforced in order not to chip away excessively.
Formula B
up according to Formula B) is brushed between ‘
adjacent dovetails on the peripheral surface of
the hub which is to be joined to the segments.
This priming ‘coating need not be continuous
between the dovetail grooves but should be put
on midway between the edges of the grooves as
, in a narrow strip extending parallel to the groove '
openings. After the benzol has evaporated, nar
row strips, of the rubber sheet mentioned above
are applied to the brushed surfaces of the hub.
The abrasive segments are then placed around,
the hub, spacers having a thickness of Iiég" being
used to obtain this distance between the adjacent
segments and the hub. The strips of rubber 30
sheet at this stage of the assembly extend only
half way across the 136,2 inch gaps.
A band or
hands are placed around the ring of segments
to hold them securely in position with respect
to each other and with respect to the hub which 35
they enclose. If additional abrasive annuli are
to be>added, i. e. superimposed upon the first
annulus, the horizontal abrasive surfaces which
are to be adjacent are primed with the solution
given by Formula B and‘benzol, and ?tted with 40
sheets prepared according to Formula A. Spacer
strips are placed on the upper surface of the
?rst annulus and. the remaining annular rows of _
segments are built up in a manner similar to
that described above in detail for the ?rst an 45
nulus. The joints between the annuli are thus
formed of the same materials and in the same
manner as the joints between segments. The
dovetail grooves in the various segments are
placed in each case directly opposite to the cor 50
responding grooves in the hub. Where it is de
‘sired to stagger the segments in adjacent annuli
the dovetail grooves in the hub may be made
with interconnecting portions between the annuli
so that all the dovetail grooves can be ?lled with
molten metal from the upper side of the assem
bled wheel. The assembled wheel segments are
placed in an oven or are covered in such a manner
that‘ the assembly can be heated up to the vul
canization temperature of the rubber.> For ex
- ample, the article may be heated up at the rate
of 25, degrees an hour to 300° F; and held at that
temperature for 12 hours. During the curing
process the gas forming material in the, rubber
strips causes them to swell so that they extend
across the gaps between segments and across the
gaps between the hub and the adjacent segments.
The-dovetail grooves in the hub and the corre
Percentage of
by weight
Smoked shee't rubber. _ H.
Plasticizer and accelerator
Sulphur ........................ .. _
4. 4
sponding grooves in the adjacent segments re
main connected so ‘that they can be ?lled with
molten metal poured in from the upper side of
v the wheel while the assembly is still hot. The
cured rubber strips form seals on each side of the
keyways so that the metal‘ ?lls substantially only
a series of keyways extending from one side of
the wheel to the other and forms a perfectly
?tting supporting surface of metal between the
base of each segment and the hub surface.
As a further modi?cation of this segmental
abrasive wheel having metal keys and resilient
joints, the dovetail keys or bars may be provided
described for the use of Formulae A and B, the
difference for the modi?cation under discussion
being that Formula D is sheeted to £2" thickness
and thus ?lls the joint spaces, and the use of
shims or solid spacers is omitted, the segments
being held in position by bands as before. When
the temperature of the joint material is approxi
mately 250°
it is soft and the bands are tight
ened just sufficiently to cause it to ?ll completely
with resilient interruptions at‘ relatively short
intervals along the length of each dovetail bar
for the purpose of localizing stresses which may
10 be set up along the length of the assembly due
the joint space volume it is intended to occupy.
to the diiferential expansion of the various parts.
and then the cure is continued to completion.
A further modi?cation may also be resorted
This can be done for example by partially ?ll
’ irrg the dovetails with metal, then interrupting
to when utilizing this invention for joining abraL
sive segments to a rotatable support. The highl
resilient nature of the joints as given by the
sheeted materials disclosed in either Formula
the pour to insert short spacers of cured resilient
15 or porous rubber, just above the cast metal sur
faces in the keyways. This step-is followed by
pouring more metal in the keyways, and if neces
or D may be substituted by a less resilient struc
ture as produced by the use of a joint material
sary additional cured rubber spacers may be in
troduced at the desired intervals, until the key
ways are completely cast. This type of key is il
lustrated in Figure 7 which shows a composite
which is heat hardenable at approximately
300° F. but which is heatdisintegrable when the 20
temperature is increased several hundred degrees
beyond 300° F. An example of an easily applied
joint material possessing these properties is:
key lying between a metal support on the left and
an abrasive segment on the right.
This com
posite key is shown as being formed of metalj
25 keys interrupted by porous rubber connecting ele
The rubber strips formed from the ingredients
given in Formula A above vulcanize into porous
elastic hard rubber joints. The principal pur
30 pose of these joints is to balance differences in
thermal expansion between the abrasive and the
supporting‘ hub.
Formula E
stage) __________________________ __
Water _______________________________ __
Inert ?ller of fused quartz ball milled and
screened into two fractions:
/ Fraction passing 40 mesh and re
Another example of joint materials which have
tain'ed on 180 meshl ____________ __
been found to serve the purposes of this invention
35 as illustrated in Figure 5 are given in Formulae
C and D. Formula C_ represents a mixture for
?lling pores in abrasive which when hardened
serves to reinforce the abrasive surface to prevent
chipping during wheel truing and so oh as de
scribed earlier in this speci?cation. Formula D
represents a rubber mixture which can be sheeted,
cut and applied to surfaces to be joined. When
cured the sheets have suitable compressibility to
relieve stresses in the assembled wheel.
Formula C
. Parts by weight
Water dispersed rubber containing.
10% } 50
Water \ 50%
sulphur _____________________________ __ 20
This mixture is of easily spreadable consistency
and is readily rubbed into the pores of an abrasive
surface. It is suitably hardened by heating 8 to 10
hours at 175° F., raising the temperature at 40° F.
per hour to 287° F. and maintaining the tempera
55 ture of 287?? F. for 8 to 10 hours.
Formula D
\ ‘
Percent by weight
Smoked sheet rubber _________ ___ _____ __
Antil-oxidant____,_ ____________________ __
Zinc oxide _______________ _.. __________ __
Carbon black ________________________ __
Sulphur__'___- ________________________ __
Rubber accelerators __________________ __
65 12 to 30 mesh ground cork ____________ __
These constituents are milled and sheeted in
the customary manner for blending rubber com
pounds, and are cured after being placed in the
70 desired locations in the assembly by raising the
temperature at the rate of 40° F. per hour to
287° F. and maintaining this latter temperature
for 90 minutes.
Per cent by weight
Phenol formaldehyde type resin (liquid
' A segmental abrasive wheel utilizing Formulae
.75 C and D is formed substantially in the‘ manner
Fraction passing 180 mesh and con
taining all ?nes ________________ __
It will be found that a cement according to
Formula E is of mortar-like, readily spreadable
consistency, that it can be rubbed into the porous
surfaces of abrasive segments for surface rein
forcement, trowelled on to the surfaces in such. 40
thicknesses that are necessary to form jointsifrom
3%" to 1%" thick if necessary), and furthermore
that it has nearly the same coeihcient of thermal ‘
expansion as a vitri?ed bonded fused alumina
abrasive; by slightly altering the ratio of resin 45
to ?ller, cements of different coef?cients ofjex
pansion can be obtained to agree closely with
a particular abrasive selected for use.
The procedure for making a segmental wheel,_
patterned alongthe lines shown in Fig. 5 in which 50
the joint materialbetween adjacent abrasive sur
faces is to be of Formula E, is .as follows, omit
ting for the sake of brevity those preparatory
steps which have been already taught by this dis
1. Apply'joint cement per Formula E to abra
sive surfaces which are to be adjacent, leaving
a moderate excess of cement upon the surfaces
so that when segments are brought together in
the desired alignment the excess material may 60
be ‘forced out leaving the joint thickness‘ (1. e.
2. Form the segments to which cement has
been applied into. an annulus; light blows with
a rawhide hammer upon the ends of segments
will serve to force the segments into the desired
locations and simultaneously force out any excess
joint cement. Fasten a steel retaining-band in
3. Harden the joint cement by heating at the 70
rate of 10° to .25" per hour to 300° F. and main
taining this temperature for 24 hours to "72 hours
depending upon the size of the wheel under con~
4. Insert the metal hub within the abrasive
annulus, heat the assembly to approximately 300°
abrasive segments mounted on a rotatable hub,
F., pour the dovetails full of molten metal such grooves in the outer surface of the hub adjacent
as that represented by~Formula N, and jar or the segments and extending parallel to the axis
' of the hub, corresponding grooves in the inner
jolt the assembly as previously described.
In those cases in which the jointing and key surfaces of the segments disposed approximately
materials which are utilized in carrying out this opposite to said grooves in the hub, a ?lling of
mechanically strong resinous material in the key
invention are of a fusible or softenable or disin—
tegrable nature, as compared to the abrasive and ways formed by pairs of oppositely disposed
hub which they serve to unite,'the replacement of grooves, and strips of resilient rubber vulcanized
in situ to join adjacent segments and to join the .10
10 defective segments is much facilitated. The as
sembly process to form an integral wheel unit hub to the segments across the gaps situated be
tween the keys.
from a support and abrasive segments is inex
5. The steps in the method of making a seg
pensive while the support and abrasive segments‘
are expensive. It is'therefore both possible and mental abrasive wheel which comprise coating
the segmental surfaces to be joined with a heat
15 economical to replace a defective segment or
segments, the procedure being simply to heat the hardenable material, hardening the coating to
wheel to such a degree that the joining materials
substantially its ?nal condition, preparing sheets
soften or disintegrate su?iciently to permit gen
of hardenable material of approximately the
tly disassembling it. Obviously, the softening, thickness of‘the joints which they are to ?ll, as
sembling the segments around a hub with said 20.
20 disintegrating or melting points of the materials
used are selected to be safely in excess of any
sheets distributed in the joint spaces, heating the
contemplated operating temperatures. The de
assembly to soften the sheets, pressing the seg
fective segments are replaced by acceptable new ments toward each other and toward the hub
segments and the Wheel'reassembled.
until the joint spaces are substantially ?lled with
Various changes may be made in the materials said material, and'raising the temperature of the
used in forming the joints and keys of the abra
assembly to complete the cure of the joint mate
sive wheel without departing from the invention, rial.
which is de?ned within the compass of the fol
6. The steps in the method of making a seg
lowing claims.
mental abrasive wheel which comprise coating
We claim:
the segmental surfaces which are to be joined 30
1, An abrasive wheel comprising a plurality of to each other and to the supporting hub with a,
abrasive segments mounted on a rotatable hub,
mixture of water dispersed rubber and vulcan
grooves in the outer surf-ace of the hub adjacent izing agent, vulcanizing the coating on said seg
the segments, corresponding grooves in the inner mental surfaces, forming rubber sheets for ?ll
surfaces of the segments disposed approximately ing the joint spaces by incorporating a vulcaniz-' 35
opposite said grooves in the hub, a metal ?lling ing agent into smoked sheet rubber, assembling
the keyways formed by pairs of oppositely dis
the segments around a hub with said sheets dis
posed grooves, and strips of resilient material tributed between the surfaces to be joined, heat
consisting of porous rubber vulcanized to a plu
ing the assembly to the softening point of the
‘sheet rubber, pressing the segments toward each 40
40 rality of the surfaces separatedby narrow gaps
to join adjacent segments and to join the hub other andthe hub until the softened rubber ?lls
to the segments across the gaps situated between the joint spaces, and completing the vulcaniza
the keys.
2. An' abrasive wheel comprising a plurality of
abrasive segments mounted on a rotatable hub,
grooves in the outer surface of the hub adjacent
the segments, corresponding grooves in the inner
surfaces of the segments disposed approximately
opposite to said grooves in the hub to ‘form a
plurality of keyways, a ?lling of metal inter
50 spersed with connections of resilient rubber in
one or more of said keyways and metal ?llings
in the remaining keyways, and strips of resilient
rubber vulcanized in situ to join adjacent (seg
ments to each other and to join the hub to' the
55 segments at positions between the keys.
3. The method of making a segmental abrasive
wheel which comprises priming the segmental
surfaces to be joined to each other and to a ro
tatable hub with a‘ suspensionjof rubber and vul
60 canizer in a liquid, vaporizing the liquid and
applying strips of sheet rubber containing vul
canizing material and a gas forming material to
the primed surfaces of the segments, assembling
7. In a segmental abrasive wheel reinforced
joints between abrasive segments comprising lay
ers of heat hardened material'?lling the pores
'in the rough surfaces adjacent joint spaces, and
bridges of tough resilient material extending
across said joint spaces and attached to saidhard
surface layers.
joints between abrasive segments comprising lay
ers of heat hardened material ?lling the. pores‘ of
the rough surfaces adjacent joint~ spaces, and
bridges of porous resilient material extending 55
across said’joint spaces and attached to said
hardened surface layers.
9. An abrasive wheel comprising a plurality of
abrasive segmentsjmounted on a rotatable hub,
grooves in the outer surface of the hub adjacent
the segments and extending parallel to the axis
of the hub, corresponding grooves in the inner
surfaces of the segments approximately opposite
to said grooves in the hub, a ?lling of metal in
of the hub and segments come approximately
opposite to one another to form keyways between
posed grooves, and strips of resilient rubber vul
canized in situ to join adjacent segments and to
join the hub to the segments‘ across the gaps sit
the hub and the segments, heating the assembled
segments and the hub to a temperature which
will cause the rubber strips to expand and bridge
the gaps between the segments and between the
8. In a segmental abrasive wheel reinforced
the segments around a rotatable hub in such posi
65 tions that dovetail grooves in adjacent surfaces
tion of the rubber in the joints.
the keyways formed by pairs ‘of oppositely dis
uated between the keys.
10. In a segmental abrasive wheel reinforced
joints between abrasive {segments comprising rel- '
‘segments and the hubjandy?lling the keyways
atively thin layers of tough non-resilient material
with metal.
4. An abrasive wheel comprising a plurality of
?lling the pores in the rough surfaces adjacent
joint spaces, and bridges of tough resilient ma
terial extending across said joint spaces and at
tached to said tough surface layers.
11. An abrasive wheel ‘comprising a rotatable
support, a plurality of abrasive segments mount
ed on the peripheral surface of said support, and
a plurality of keys formed of hard thermoplastic
resin interconnecting each of said segments and
said rotatable support.
12. The steps in the method of making a seg
10 mental wheel which comprise coating with a
heat-hardenable material the segmental surfaces
intersegmental material, and raising the temper- ‘
ature of the assembly to complete the cure of the
intersegmental material.
13. An abrasive wheel comprising a plurality of
abrasive segments mounted on a rotatable hub,
grooves in the outer surface of the hub adjacent
the segments and extending parallel to the axis of
the hub, corresponding grooves i the inner sur
faces of the segments approxim tely opposite to
said grooves in the hub, a ?lling of metal in the 10
keyways formed by pairs of oppositely disposed
to be joined, hardening the coating to [substan .1 grooves, bridges of tough resilient material join
tially its ?nal condition, assembling the segments ing the hub to the segments across the gaps that
around a hub with small gaps between adjacent
15 segments and at least partially ?lling said gaps
with a heat-hardenable material, pressing the
segments toward each other and toward the hub
until said gaps are substantially ?lled with the
are located between the keyways, and similar
bridges between adjacent segments.
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