U.S. patent application number 17/678410 was filed with the patent office on 2022-06-09 for three layer grinding wheel.
The applicant listed for this patent is ATLANTIC GmbH. Invention is credited to Karsten KORSCHELT, Peter REHLICH, Marco WEBER, Ingolf WIEGNER.
Application Number | 20220176517 17/678410 |
Document ID | / |
Family ID | 1000006221651 |
Filed Date | 2022-06-09 |
United States Patent
Application |
20220176517 |
Kind Code |
A1 |
WIEGNER; Ingolf ; et
al. |
June 9, 2022 |
THREE LAYER GRINDING WHEEL
Abstract
A multilayer circular grinding wheel includes at least three
substantially planar layers including an inner layer and two outer
layers immediately adjacent to the inner layer, of which at least
the inner layer has a proportion of diamond abrasive grit, the
proportion of diamond in the abrasive grit being greater in the
inner layer than in the outer layers.
Inventors: |
WIEGNER; Ingolf; (Kaarst,
DE) ; REHLICH; Peter; (Meckenheim, DE) ;
KORSCHELT; Karsten; (Bonn, DE) ; WEBER; Marco;
(Koln, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ATLANTIC GmbH |
Bonn |
|
DE |
|
|
Family ID: |
1000006221651 |
Appl. No.: |
17/678410 |
Filed: |
February 23, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2020/073533 |
Aug 21, 2020 |
|
|
|
17678410 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24D 99/005 20130101;
B24D 3/344 20130101; B24D 5/14 20130101; B24D 3/346 20130101; B24D
3/28 20130101 |
International
Class: |
B24D 5/14 20060101
B24D005/14; B24D 3/28 20060101 B24D003/28; B24D 3/34 20060101
B24D003/34; B24D 99/00 20060101 B24D099/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 23, 2019 |
DE |
10 2019 122 711.9 |
Claims
1. A multilayer circular grinding wheel comprising: at least three
substantially planar layers including an inner layer and two outer
layers immediately adjacent to the inner layer, of which at least
the inner layer has a proportion of diamond abrasive grit such that
the proportion of diamond in the abrasive grit is greater in the
inner layer than in the outer layers.
2. The grinding wheel according to claim 1, wherein the inner layer
has a proportion of at least 50% by weight of diamond in the
abrasive grain.
3. The grinding wheel according to claim 1, wherein the inner layer
has a proportion of at least 75% by weight of diamond in the
abrasive grain.
4. The grinding wheel according to claim 1, wherein the inner layer
has a proportion of at least 90% by weight of diamond in the
abrasive grain.
5. The grinding wheel according to claim 1, wherein the outer
layers each have a proportion of less than 90% by weight diamond in
the abrasive grain.
6. The grinding wheel according to claim 1, wherein the outer
layers each have a proportion of less than 75% by weight diamond in
the abrasive grain.
7. The grinding wheel according to claim 1, wherein the outer
layers each have a proportion of less than 50% by weight of diamond
in the abrasive grain.
8. The grinding wheel according to claim 1, wherein the grinding
wheel includes exactly three layers including abrasive grains.
9. The grinding wheel according to claim 1, wherein the outer
layers have a same structure or substantially a same structure, and
a same axial thickness or substantially a same axial thickness.
10. The grinding wheel according to claim 1, wherein the inner
layer and the outer layers are made of a synthetic resin bond.
11. A method of using the grinding wheel according to claim 1.
12. The method according to claim 11, wherein the grinding wheel is
bonded with an outer side to a metallic support plate.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority to German
Patent Application No. 102019122711.9 filed on Aug. 23, 2019 and is
a Continuation Application of PCT Application No. PCT/EP2020/073533
filed on Aug. 21, 2020. The entire contents of each application are
hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a grinding wheel and to a
use of such a grinding wheel.
[0004] 2. Description of the Related Art
[0005] Grinding wheels consisting of a single homogeneous layer of
abrasive material are generally known. For example, WO 2006/079444
A1 shows a grinding wheel with a homogeneous layer of
diamond-containing abrasive grain in a synthetic resin bond for
grinding ceramic balls. The grinding wheel is acted upon in the
axial direction, and the balls to be ground run in grooves aligned
concentrically to the axis of rotation.
[0006] Multi-layer grinding wheels are also known, for example from
the document JP 2003300166 A, which discloses a grinding wheel with
three layers arranged on top of each other in a sandwich-like
manner in the axial direction is described. The grinding wheel is
part of a grinding device for precise cuts in the radial direction.
Particularly good dimensional accuracy is to be achieved in that a
middle layer with relatively coarse abrasive grit is made of
diamond, while the two axially adjacent outer layers are made of
abrasive grit of diamond with a finer grain size. In use, wear of
the two outer layers causes the grinding peripheral surface of the
wheel to become convex so that the wheel centers itself in the
workpiece. Further, CN106944938 discloses a three-layer grinding
wheel in which the two outer layers contain a proportion of diamond
abrasive grit, while the middle or inner layer contains alumina and
synthetic resin. This design improves heat dissipation through the
inner layer of the grinding wheel.
[0007] Grinding wheels with a matrix containing homogeneous or
equal amounts of diamond abrasive grit in all layers are expensive
to manufacture. A three-layer grinding wheel with a middle or inner
layer free of diamond abrasive grit is not suitable for grinding
ceramic balls.
SUMMARY OF THE INVENTION
[0008] Preferred embodiments of the present invention provide
grinding wheels each including at least three layers, is less
expensive to manufacture than the prior art, and is particularly
suitable for grinding ceramic balls.
[0009] Because a grinding wheel according to a preferred embodiment
of the present invention is provided with an inner or middle layer
and at least two outer layers, and the inner layer has a higher
proportion of diamond in the abrasive grit than the two outer
layers immediately adjacent to the inner layer, it is possible to
save on diamond abrasive grit compared with grinding wheels with
homogeneous construction or grinding wheels with layers that differ
only in grit size but not in diamond content. In addition, such a
grinding wheel can be used advantageously for grinding ceramic
balls, since the guide grooves are quickly formed in the outer
layer coming into contact with the balls, and the inner layer acts
predominantly or exclusively abrasively, i.e., to perform the
actual grinding process.
[0010] Advantageously, at least the inner layer is designed with
abrasive grain in a synthetic resin bond. It is further
advantageous if the two outer layers directly adjacent to the inner
layer on a respective surface side of the inner layer have the same
abrasive grain, and in particular, it is further advantageous that
these two outer layers have the same thickness or substantially the
same thickness in the axial direction.
[0011] When used for ball grinding, the new grinding wheel is
preferably bonded with one outer plane side to a metallic backing
plate. The outer layer lying directly on the backing plate is then
not used for grinding or guiding purposes during ball grinding.
However, it has proved advantageous to provide this layer opposite
to the other outer layer, which is of identical design, since this
reduces or minimizes distortion of the entire grinding wheel and in
particular of the inner layer during production.
[0012] The above and other elements, features, steps,
characteristics and advantages of the present invention will become
more apparent from the following detailed description of the
preferred embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Examples of preferred embodiments of the present invention
are described below with reference to the drawings.
[0014] FIG. 1 shows a section of a three-layer grinding wheel in a
view in the radial direction.
[0015] FIG. 2 shows the grinding wheel of FIG. 1 with prepared
guide grooves for use in ball grinding.
[0016] FIG. 3 shows the grinding wheel from FIG. 1 and FIG. 2 in
its use for ball grinding in a corresponding device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] In FIG. 1, a grinding wheel 1 according to a preferred
embodiment of the present invention is schematically illustrated in
a cross-section in broken-off form. The grinding wheel 1 includes
an inner layer 2, which is sandwiched between a first outer layer 3
and a second outer layer 4. The inner layer 2 has a higher
proportion of diamond in the abrasive grain than the two outer
layers 3 and 4. For example, the inner layer 2 may have a
proportion of 50% by weight (wt%), 75% by weight or even 90% by
weight of diamond in the abrasive grain. This specification is the
proportion in the abrasive grain without the bond matrix. In a
preferred embodiment, the abrasive grain may also consist of 100%
diamond. The grit size of the abrasive grain is not essential to
preferred embodiments of the present invention. Suitable grit sizes
are known from the prior art.
[0018] The two outer layers 3 and 4 have the same or essentially
the same structure. They also contain abrasive grit, but with a
lower or no diamond content. Thus, the content of diamond in these
two layers may be less than 50% by weight, in particular less than
25% and even less than 10%. In a preferred embodiment, the two
outer layers 3 and 4 are essentially free of diamond abrasive
grain, i.e., except for impurities or traces unavoidable in the
manufacturing process.
[0019] If the inner layer 2 is not manufactured with 100% of
diamond abrasive grit, the required total of 100% can be
supplemented with less expensive abrasive grit such as corundum
(Al.sub.2O.sub.3), in particular high-grade corundum, silicon
carbide (SiC), but also any other known abrasive grit. The two
outer layers also contain conventional abrasive grit. In
particular, in the preferred embodiment in which the two outer
layers 3 and 4 are free of diamond abrasive grit, all of the
abrasive grit is selected from lower cost material such as
corundum, SiC, another abrasive grit, or a mixture of the eligible
non-diamond abrasive grits.
[0020] The inner layer 2 and the outer layers 3 and 4 are produced
by hot pressing in a synthetic resin bond. The ratio between
abrasive grit and synthetic resin is suitably selected, as is
common in the prior art. The pore volume of an abrasive wheel
according to a preferred embodiment of the present invention is
preferably between 3 and 10%.
[0021] The essentially identical structure of the two outer layers
3 and 4 ensures that the grinding wheel practically does not warp
during or after manufacture, for example, in the cooling phase. In
the case of a grinding wheel with an outer layer applied on only
one side, warpage is to be expected due to different heat
conduction and heat capacity as well as due to different thermal
expansion of the materials.
[0022] The grinding wheel is a circular wheel, which is
rotationally symmetrical to an axis D.
[0023] The thickness in the direction of the axis D can be selected
depending on the application. Thus, the dimensions of the wheel and
of the individual layers 2, 3 and 4 are selectable and dependent on
the application situation. The wheel diameter can also be selected
and adapted to the needs of the grinding machine. In particular,
the thickness of the outer layers 3 and 4 can be smaller than the
thickness of the inner layer 2, as these mainly serve to stabilize
the grinding wheel. Layer 3, which serves as the infeed layer for
the ceramic balls, is ground down after hot pressing to a dimension
appropriate for the application, i.e., for the ball diameters to be
ground in use.
[0024] FIG. 2 shows the grinding wheel 1 from FIG. 1 in a likewise
cut, broken-off representation. Here it can be seen in
cross-section that, compared with the initial situation in FIG. 1,
the upper outer layer 3 is subsequently (after hot pressing)
provided with guide grooves 5, which prepare the grinding wheel 1
for use in ball grinding. The guide grooves 5 are concentric,
circular circumferential grooves which are arranged in the outer
surface of the outer layer 3 and which are symmetrically and
concentrically aligned with respect to the axis of rotation D.
[0025] FIG. 3 illustrates the use of the grinding wheel 1 according
to a preferred embodiment of the present invention for ball
grinding on a machine with a vertical drive axis. FIG. 3 shows in a
schematic representation the device for ball grinding in a side
view. Here, a stationary guide disc 1 is provided, preferably made
of cast steel. The guide disk 10 has circumferential guide grooves
11 on its underside, in which a plurality of balls 12 to be ground
are guided. From the underside, a backing plate 13 is provided with
the grinding wheel 1 arranged thereon with the inner layer 2 and
the two outer layers 3 and 4, which is to be set in rotation by a
drive shaft 15.
[0026] For grinding, a pressure P is exerted on the stationary
guide disk 10 from the upper side. The backing plate 13 is set in
rotation by a drive, so that the balls 12 roll in the guide grooves
11 and in particular also in the guide grooves 5 of the grinding
wheel 1. While the guide grooves in the first outer layer 3 do not
yet make any appreciable contribution to the ablation of ceramic
balls, the effective grinding process begins when the balls 12 have
worked their way through the layer 3 and come into contact with the
diamond-containing layer 2. The speed differences in the different
areas of the guide grooves cause the abrasive grain to move
relative to the surface of the ceramic ball. The abrasive grain
then causes an abrasion of the surface of the ball and thus an
improvement of the surface quality and the ball shape.
[0027] A grinding wheel according to a preferred embodiment of the
present invention can be used on a ball grinding machine with a
vertical drive shaft as well as on a ball grinding machine with a
horizontal drive shaft.
[0028] An advantage of the grinding wheel described in this
respect, especially when used for ball grinding, is that the entire
thickness of the inner layer 2 can be used for the grinding
process. The outer layers, which are manufactured with less
expensive abrasive grit, serve only for the initial guidance of the
ball blanks in the guide groove 5 and to fasten the grinding wheel
on the backing plate 13. The supporting layer 4 has the further
effect that the grinding diamond-containing layer 3 can be used up
to the breakthrough and, in contrast to single-layer discs, a
reduction of the diamond material to be discarded is thus achieved.
If both tasks were performed by the diamond layer in the case of a
single-layer diamond grinding wheel, the overall consumption of
diamond abrasive grain is higher than in the case of the multilayer
grinding wheel shown above with an inner layer containing a higher
proportion of diamond. Furthermore, the softer running-in layer 2
leads to the fact that the process of groove formation on the one
hand takes place significantly faster than in the hard diamond
layer and on the other hand the number of ball batches with low
quality is reduced.
[0029] While preferred embodiments of the present invention have
been described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present invention. The
scope of the present invention, therefore, is to be determined
solely by the following claims.
* * * * *