Note: Descriptions are shown in the official language in which they were submitted.
A Dressing Roll for Grinding Wheels
Field of the Invention:
This invention relates to a dressing roll for grinding wheels.
Background of the Jnvention:
0 As is well known the term dressing means the fine machining of a rotating
grinding member. The purpose thereof is the making or remaking of the geometrical
shape and/or the abrasive property of the coating of the grinding member or tool.
Grinding tools the coating of which includes hard material grains or CBN grains
(boron nitrite grains) generally are machined by dressing rolls having diamond coa-
tings. It has become known to provide profiled diamond dressing rolls or formed
diamond dressing rolls which are coated by coatings including diamond grains. One
disadvantage of such dressing rolls is that the obtainable minim~l radius is relatively
substantial. Therefore, it is difficult to satisfactorily dress grinding wheel profiles of
small radii. Basically, it would be possible to perform such dressing by a single dia-
mond. However, single diamonds wear relatively quickly. Replacement of the single
diamonds in the carrier member requires a lot of time.
When for example gear members are ground by grinding wheels of not preci-
sely dressed geometries, the required geometrical shape of the tooth profile will not
be obtained. This may result in additional vibrations causing undesired noises in the
gear mechanism and even in broken teeth. The precision obtainable by grinding de-
pends on the preciseness of the grinding surface, and this depends on the preciseness
of the shape of the dressing tool.
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Summary ofthe Invention:
It is an object of the invention to provide a dressing roll including diamonds,
s in particular for dressing CBN grinding wheels which dressing roll has a long ser-
vice life, is adapted to provide for minim~l radii and which allows to precisely ma-
chine coating surfaces.
To this end the present invention provides a dressing roll for grinding wheels,
said dressing roll including: a circular disk member of resilient material and having
o circumferentially spaced radial holding slots at its periphery, a plurality of diamonds
of substantially same dimensions adapted to be substantially fittingly received in
said holding slots, and at least one support disk of deflection resistent material on
one side of said disk member and having an outer radius approximately similar tothe outer radius of said disk member.
s The dressing roll of the present invention includes at least three parts,namely
a circular disk member having radial holding slots at its periphery, elongated dia-
monds received in said holding slots, and at least one support disk on at least one
side of the disk member.
The diamonds may be monocrystalline diamonds (MKD) or polycrystalline
diamonds (PKD) which are inserted into the holding slots. The diamonds preferably
are dimensioned such that they are clampingly received in the holding slots. Thedimensions of the diamonds are within certain tolerances. Selection of the diamonds
ensures that the diamonds are clampingly received in the holding slots. Compensa-
tion of the dimensional tolerances of the diamonds may be obtained by providing
2s radial compensation slots at the periphery of the disk members between adjacent
holding slots in predetermined circumferentially spaced relationship, which com-pensation slots enable the segments therebetween to yield when the diamonds are
overdimensioned. The compensation slots allow to compensate for any tolerances of
the diamonds which may be of elongated shape. Preferably holes are provided in the
area of the compensation slots to receive fastening means such as screws which al-
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low to spread more or less the segments adjacent to the compensation slot so as to
exert clamping forces upon the diamonds inserted in the holding slots.
The diamonds are ground at their outer ends so as to provide for a predeter-
mined geoemtry, i.e. a radius. In order to use a small radius it is preferred that the
support disk adjacent to the diamonds in an axial direction be of only small dimen-
sions, preferably of conical shape such that a very acute angle will result. Such a
dressing roll, therefore, allows to provide predetermined radii at the grinding tools.
The dressing roll of the invention allows to obtain substantial advantages.
The diamonds are mechanically fixed and therefore may be replaced if this is requi-
o red. The use of a large number of individual diamonds at the periphery of the dres-
sing roll increases the useful service life significantly as compared to that of e.g. a
single diamond. Furthermore, lifetime of the dressing roll may be increased by fre-
quent grinding thereof.
The structure of the dressing roll (modular structure of the individual parts)
allows to manufacture the dressing rolls precisely in a reproducible manner. Thesingle parts may be premanufactured.
As already explained the indivudal diamonds may be mechanically clamped
within the holding slots. Preferably, in order to improve the uniform clamping of
diamonds, said holding slots have radially inwards extended portions of a width
20 which is smaller than that of said holding slots so as to define between said holding
slots segments adapted to be deflected within the plane of said disk member.
Preferably, the segments are shaped such that, as a result of a deformation thereof,
the surfaces of the holding slots which clamp a diamond are displaced in substantial-
ly parallel relationship to each other so that substantially planar clamping is ensured.
In order to improve the deflection characteristics of the segments the inner ends of
the extended slot portions each may open into a hole. Enlarged slot areas may beprovided in the area of the extended slot portions. The bit of a screwdriver for ex-
ample may be inserted into said enlarged slot areas so as to spread adjacent seg-
ments. This allows to remove a diamond and replace it by another diamond.
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The support disks are preferably of conical shape at their periphery and pre-
ferably include a very small angle thereat. The support disks preferably are of a hard
material which may be ground together with the diamonds. Grinding of the dia-
monds requires a special grinding coating which could smear the material when
5 support wheels of steel are used. This is not the case when hard materials such as
cermet or ceramics are used. Preferably the invention uses a hard metal, cermet,ceramics, or a steel coated by a hard material. Such material is also advantageous
because it is resistent to bending when the diamonds are loaded.
Said disk member and said at least one support disk are axially clamped toge-
o ther, preferably by suitable screw means. Since the thickness of the diamonds varieswithin tolerances, it is preferred to provide a compensation layer between the disk
member and the support disk. The compensation layer may be made of plastics, a
molding alloy, a solder alloy, cellulose, galvanically separated metal or the like.
When two or more disk members are clamped between a pair of substantially simi-
lar support disks, a compensation layer may be disposed also between the disk
members. When two or more disk members having holding slots of identical cir-
cumferential spacings are used, the diamonds of the respective disk members may
be axially aligned or circumferentially offset with respect to each other.
When the dressing roll is to be formed as a conical roll, the disk member may
20 be shaped as a conical disk in its radially outer area and may be supported on one
side by a matingly shaped support disk. Such a conical dressing roll allows precisely
to machine planar coatings of CBN disks or the like. In such an arrangement the dia-
monds preferably are of thickness somewhat in excess of the thickness of the coni-
cal portion of the disk member so that they may become effective in the plane of the
25 cone envelope.
Two or more diamonds may be radially staggered. The radially staggered dia-
monds may be disposed either in common slots or in separate slots; in the latter case
the diamonds would be offset with respect to each other. Diamonds arranged alongdifferent pitch circles may be positioned under different cone angles.
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Such a conical dressing roll may be made by different methods. One such
method includes the making of a pair of rotationally symmetrical formed members,preferably by turning. One of said formed members includes a concial recess and
preferably has a cylindrical periphery. The other formed member includes an axially
s extending conical portion which is fittingly received in said conical recess. The
second formed member may also be of cylindrical shape, preferably with a diameter
identical to that of the first formed member. Furthermore, the second formed mem-
ber may be provided with an axial land which is fittingly received in a central bore
of the first formed member. The two formed members are clamped together; there-
10 after they may be provided with bores to receive connecting bolts. Furthermore, thefirst formed member will be machined (by turning) on its side remote from the
second formed member, in particular to form a conical disk portion in its radially
outer area. Thereafter the first formed member will be released from the second
formed member, and the conical disk area will be machined to make holding slots
and compensation slots if desired. This machinig may be performed in different
ways, for example by punching, eroding, laser operations etc. Thereafter, the first
and second formed members are again clamped together, and at the same time or
before the diamonds are inserted into the holding slots. When the diamonds are
fixed, the second formed member will be machined on its side remote from the first
20 formed member as to obtain a conical disk which is received by the first formed
member, i.e. in its conical recess. The diamonds extend slightly beyond the outer
periphery of such conical disk. Thereafter, the diamonds are ground to obtain the
desired geometrical shape, for example a radiused shape.
In the following the invention will be explained in more detail with reference
25 to examples shown in the drawings.
Fig. 1 is an elevation of a disk member of the dressing roll of the invention.
Fig. 2 shows a detail of the disk member in Fig. 1 on an enlarged scale.
Fig. 3 shows an exploded view of a dressing roll including a pair of disk
members shown in Fig. 1 and a pair of support rolls.
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Fig. 4 shows the mounted assembly of a dressing roll of the invention accor-
ding to Fig. 3, however, including only one disk member.
Fig. 5 is a view of the dressing roll in Fig. 4 as seen in the direction of arrow
5.
Fig. 6 shows six method steps of making a conical dressing roll of the inven-
tion.
Fig. 7 is a side elevation, partially in section, of the final conical dressing roll.
Fig. 8 is a side elevation of the conical dressing roll in Fig. 7 as seen in thedirection of arrow 8.
o Fig. 9 shows a detail ofthe dressing roll in Fig. 8 on an enlarged scale.
Fig. 1 shows a flat annular disk member 10 of steel of a thickness between
0.8 and 1 mm for example. At its outer periphery disk member 10 is provided with a
row of holding slots 12 having a predetermined circumferential spacing. Details of
the holding slots 12 are shown in Fig. 2. As may be seen the slots 12 comprise aholding portion 14 which is interrupted by a projection 16 extending into the slot 12.
Below the projection 16 there is a slot portion 18 which is of a greater width than
the portion 14. Below the portion 18 there is an arcuate narrow slot portion ~0
which opens into a circular hole 22. This structure provides for radial segments 24
between slots 12; segments 24, due to the shape of the slots, are resiliently deform-
able, i.e. they may be deformed also within the plane of disk member 10; during
such deformation the opposite faces of the slot portion 14 will be displaced such that
they will remain substantially parallel to each other.
Furthermore, Fig. 2 shows a radial compensation slot 26 which subdivides a
segment 24 substantially centrally between adjacent holding slots 12. A circularhole 28 is provided approximately at the center of the longitudinal extent of the
compensation slot 26. The circular hole may have a chamfer (not shown) for recei-
ving a (not shown) bolt, screw or other clamping element. The bolt, screw or clamp-
ing element may be used to spread more or less the respective segment portions
formed by the compensation slot 26.
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Elongated or rod-like diamonds 32 will be inserted into the holding portions
14 of the slots. The diamonds are of a length of for example 4 mm and may be of
substantially square cross-section of e.g. 0.8 x 0.8 mm. The width of the holding slot
portions 14 may also be substantially 0.8 mm varying within tolerances as indicated
5 in Fig.2. The dimensions of the diamonds 32 also vary within substantial toleran-
ces. When the width of a diamond 32 is identical to that of a holding slot portion 14,
the diamond will be fittingly received therein. When the diamonds 32 are selected to
be inserted into the holding slots 12 the following procedure will be preferred:When an e.g. overdimensioned diamond is inserted into a holding slot, an under-
10 dimensioned diamond should be inserted in the following slot and possibly also in
the next following slot so that all diamonds will be clampingly received in the slots
between adjacent compensation slots. A still remaining overdimensioning then maybe compensated for by the compensation slot 28. On the other hand a remaining un-
derdimensioning between adjacent compensation slots may be compensated for by
spreading the compensation slot 26 by means ofthe above mentioned screw or bolt.The length ofthe holding slot portion 14 or the diamond 32 is such that the diamond
32 will be received in slot 12 in a predetermined arrangement.
Fig.3 is a side elevation of a pair of disk members 10a, 10b which are similar
to disk member 10 containing diamonds 32. The disk members 10a, 10b can be
20 positioned relative to each other in different ways, for example such that the dia-
monds 32 are axially aligned or are circumferentially offset with respect to each
other. Furthermore, different circumferential spacings of the holding slots of disk
members 10a, 10b may be selected. Furthermore, the diamonds may be retained by
both disk members uniformly so as to provide for an overlap in the axial direction.
Furthermore, Fig.3 shows a pair of support disks 34,36 including an annular
land 38 and 40, respectively, on their sides remote from disk members 10a and 10b
and having conical disk portions 42 and 44, respectively, with a very small coneangle of for example 12 to 23~ at their radially outer ends. Finally, Fig.3 shows a
mounting sleeve 46 including a sleeve portion 48 adapted to be fittingly passed
30 through the openings of the support disks 34,36 and the disk members 10a, 10b,
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and a flange portion 50. The mounting sleeve 46 is provided to assist in assembling
the shown parts and, if desired, to calmp the dressing roll of Figs. 4 and 5 in a dres-
sing machine. As indicated in Fig. 3 the shown parts are clamped together by screws
or bolts, with a bolt being indicated at 52. The bores in the support disks 34, 36 are
5 preformed or may be bored after assembly of all parts, with the disk members 1 Oa,
lOb also including thrubores for bolts 52.
The parts shown in Fig. 3 after assembly thereof are shown, without the
mounting sleeve in Fig. 4. However, only one disk member lO is disposed between
the support disks 34, 36. As may be seen a small angle a of for example only 25~ is
o provided at the periphery of the assembly. Of course the angle a may be chosen so
as to be larger. After the assembly the diamonds 32 are ground to provide for a
small radius thereof, for example between 0.05 and 0.5 mm. The support disks 42,44 are made of a material which can be ground together with diamonds 32. Such
material is for example hard metal, cermet, ceramics, steel coated with a hard mate-
rial, or the like.
In order to compensate for tolerances of the thickness of the diamonds a re-
spective compensation material may be disposed between the disk members 10 or
lOa, lOb and the support disks 34, 36. Such a compensation material may be for
example plastics, a molding alloy, a solder alloy, cellulose or a galvanically separa-
20 ted metal.
Fig. 6a shows two members 54, 56, with member 54 being a cylindrical parthaving a central bore and a conical recess 58 on one side as indicated by dotted li-
nes. Recess 58 extends to the outer periphery of the formed member 54. The formed
member 56 includes also a cylindrical portion 60 being of the same diameter as
25 formed member 54 and also including a conical portion 62 which is complementary
to recess 58. Integral with the conical portion 52 is an axial hub portion 64 which is
fittingly received in the bore of the formed member 52. The formed member 56 hasa thrubore as indicated by dotted lines.
Fig. 6b shows the manner in which the formed members 52, 56 are clamped
together. There are bores one of which is indicated at 64 by dotted lines. As may be
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seen in Fig. 6c the formed member 54 has been machined so as to provide for a co-
nical disk 66 having an axial land 68. The conical disk 66 is shown by itself, in part
section, in Fig. 6d after the formed member 56 has been removed.
The conical portion of the conical disk 66 may be provided, for example, by
5 eroding, with holding slots 12a which are approximately similar to the holding slots
12 in Fig. 2. Therefore, the shape of slots 12a will not be described in more detail.
Furthermore, there are provided compensation slots 26a. The holding slots 12 recei-
ve rodlike diamonds 32a. As may be seen in Fig. 7, the diamonds 32a project be-
yond the plane of the outer cone surface. As a result such cone surface and the base
o of the cone include an angle of about 20~.
When the disk 66 has been manufactured it will be reassembled with the
formed member 56a as may be seen in Fig. 6e. Thereafter, bores 70 and 72 will bebored into the formed member 56 substantially perpendicularly to the conical porti-
on of disk 66. When the diamonds 32a have been assembled in accordance with Fig.6f, the disk 66 may be additionally fixed to the formed members 56 by bolts 74. The
lower bolts may extend through bores 76 (Fig. 8), and the upper bolts 74 may ex-tend into chamfered bores 28a in order to clampingly hold the diamonds 32a in the
disk 66.
In a last step the formed member 56 will be machined such as to provide for a
20 conical disk 78 according to Fig. 7 which will be completely received in the conical
disk 66.
The result is a conical dressing roll. Thereafter the diamonds 32a will be gro-
und to provide for a radiused shape thereof.
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