U.S. patent application number 10/478301 was filed with the patent office on 2005-01-06 for grinding wheel, intermediate product and method for producing a grnding wheel of this type.
This patent application is currently assigned to Sia Abrasives Industries AG. Invention is credited to Muller, Patrick.
Application Number | 20050000166 10/478301 |
Document ID | / |
Family ID | 8183961 |
Filed Date | 2005-01-06 |
United States Patent
Application |
20050000166 |
Kind Code |
A1 |
Muller, Patrick |
January 6, 2005 |
Grinding wheel, intermediate product and method for producing a
grnding wheel of this type
Abstract
A grinding wheel for the grinding of curved surface portions (0)
consists basically of a carrying body (2, 12) and an abrasive (3,
13, 23) applied to the carrying body. The carrying body (2, 12) has
a circumferential surface (4), of which the section relative to a
radial plane (R) has a curvature. The abrasive (3, 13, 23) is
arranged on the carrying body (2, 12), at least in the region of
the circumferential surface (4). The abrasive thereby likewise has,
in section, relative to the radial plane (R), a curvature which
corresponds essentially to the curvature of the circumferential
surface (4).
Inventors: |
Muller, Patrick; (Huttwilen,
CH) |
Correspondence
Address: |
SHOEMAKER AND MATTARE, LTD
10 POST OFFICE ROAD - SUITE 110
SILVER SPRING
MD
20910
US
|
Assignee: |
Sia Abrasives Industries AG
Franuenfeld
CH
8501
|
Family ID: |
8183961 |
Appl. No.: |
10/478301 |
Filed: |
September 1, 2004 |
PCT Filed: |
June 6, 2002 |
PCT NO: |
PCT/EP02/06214 |
Current U.S.
Class: |
51/309 ;
451/541 |
Current CPC
Class: |
B24D 7/00 20130101; B24D
13/04 20130101; B24D 7/18 20130101; B24D 9/00 20130101 |
Class at
Publication: |
051/309 ;
451/541 |
International
Class: |
B24B 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 12, 2001 |
EP |
01810563.5 |
Claims
1. A grinding wheel for grinding curved surface portions comprising
a carrying body and an abrasive applied to the carrying body,
wherein the carrying body has a circumferential surface which has,
in section in a radial plane, at least partially a convex
curvature, and wherein the abrasive is arranged on the carrying
body, at least in the region of the circumferential surface, so
that the abrasive has, in section, relative to the radial plane R,
a curvature which corresponds approximately to the curvature of the
circumferential surface.
2. A grinding wheel of claim 1, wherein the carrying body is
designed as a ring.
3. A grinding wheel of claim 1, wherein the crying body is designed
as a disk.
4. A grinding wheel of claim 1, wherein the abrasive is clamped on
the carrying body by means of a clamping device.
5. A grinding wheel of claim 4, wherein the clamping device is
provided with a holding means for fastening the grinding wheel to a
grinding machine.
6. A grinding wheel of claim 1, wherein the abrasive is glued to
the carrying body.
7. A grinding wheel of claim 1, wherein the abrasive consists of
segments which are arranged on the carrying body preferably so as
to overlap in the circumferential direction.
8. A grinding wheel of claim 7, wherein the segments are of
almond-shaped design.
9. A grinding wheel of claim 2, wherein the abrasive is designed as
a belt which is wound in coils on the ring preferably so as to
overlap, as seen in the circumferential direction.
10. A grinding wheel of claim 7, wherein the overlap is designed in
such a way that the distance of the front end of the segments
respectively the coils, in the direction of rotation, from the axis
of rotation is shorter than the distance of the rear end, in the
direction of rotation, from the axis of rotation.
11. A grinding wheel of claim 1, wherein the abrasive is designed
as a belt which, as seen in the circumferential direction, is
applied to the carrying body at least on an outer circumferential
line of the circumferential surface.
12. A grinding wheel of claim 11, wherein the belt i is provided
along its edges with indentations or cutouts
13. A grinding wheel of claim 1, wherein the circumferential
surface has a radius of curvature of 3 mm to 8 mm.
14. A grinding wheel of claim 1, wherein the carrier consists of
glass-fiber-reinforced plastic.
15. An intermediate product for the production of a grinding wheel
of claim 7, wherein the segments are fastened with an inner end to
the carrying body and wherein the outer end of the segments
projects beyond the outer, circumferential line of the carrying
body.
16. A method of making a grinding wheel of claim 7, comprising
steps of providing an intermediate product comprising abrasive
segments arranged on a carrying body so as to overlap in a
circumferential direction, the segments having an outer end
fastened to the carrying body and an outer end projecting beyond an
outer circumferential line of the carrying body, bending of the
outer ends of the segments around the curved circumferential
portion and fastening of the outer ends to the carrying body.
Description
[0001] The invention relates to a grinding wheel for the grinding
of curved surface portions and also to an intermediate product and
to a method for the production of such a grinding wheel, having the
features of the preamble of the independent claims.
[0002] Various types of grinding wheels are known. The grinding of
flat surfaces, for example, sheetlike wheels are used, to one or
both sides of which an abrasive is applied.
[0003] It is known from U.S. Pat No. 5,722,881, to apply abrasive
flaps to the outside of a disk-shaped carrier.
[0004] EP 911 116 discloses grinding wheels, in which abrasives are
arranged next to one another in segments, so as to overlap, on both
surfaces.
[0005] These known grinding wheels are suitable for the grinding of
essentially flat surfaces. In specific applications, however, it is
desirable to grind radii, for example in the case of weld seams
which connect sheetlike parts to one another. Above all with regard
to applications where there are stringent hygiene requirements or
where corrosion is to be avoided, it is important that the surface
of the weld seam is smooth, in particular has no depressions or
pores. Such concavely curved surfaces can be ground with relatively
poor quality by means of conventional grinding wheels.
[0006] An object of the present invention is, therefore, to avoid
the disadvantages of the known prior art, in particular, therefore,
to provide a grinding wheel which is suitable for the grinding of
curved concave surfaces. The grinding wheel is to be capable of
being produced in a simple way and is to have long service
life.
[0007] These objects are achieved, according to the invention, by
means of a grinding wheel having the features of the characterizing
part of claim 1.
[0008] The grinding wheel consists basically of a carrying body and
of abrasive applied to the carrying body. By "abrasive" is meant in
this connection, in particular, a flexible sheetlike carrier which
is provided with abrasive, that is to say, typically, a grinding
belt or sections from a grinding belt or a flat grinding wheel. It
is also conceivable, however, to apply abrasive directly, and
without a carrier, to the carrying body, in particular to glue
abrasive material directly to the carrying body.
[0009] The grinding wheel is rotatable about an axis, for example
by means of a grinding machine. The carrying body has a
circumferential surface which, in section in a radial plane, has at
least partially a concave curvature. A radial plane is a plane
which runs through the axis of rotation. The abrasive is arranged
on the carrying body, at least in the region of the circumferential
surface. The abrasive therefore likewise has, in section, relative
to the radial plane, a curvature which corresponds approximately to
the curvature of the circumferential surface.
[0010] The grinding wheel according to the invention is of
approximately rotationally symmetrical design. Of course, as seen
in the circumferential direction, the outer surface of the carrying
body has a curvature. Here and hereafter, by the "curvature of the
circumferential surface" is meant the curvature of the
circumferential surface in a radial plane.
[0011] Since the carrying body is provided with a convex
circumferential surface and the abrasives are applied to the
carrying body, at least in the region of the circumferential
surface, concave surface portions can be ground in a simple
way.
[0012] Since, according to the invention, an abrasive is applied to
a carrying body having a predetermined shape with a curvature, the
shape of the abrasive is at all times defined exactly by the
carrying body. In contrast to bound abrasives, in which the shape
of the grinding surface may change in the course of time due to the
removal of the abrasive, the curved grinding surface according to
the invention remains defined over the lifetime of the grinding
wheel.
[0013] According to a first exemplary embodiment, the carrying body
is designed as a ring. Designing the carrying body as a ring has
various advantages. Thus, the carrying body can be produced at a
relatively low outlay in terms of material. Moreover, a carrying
body designed as a ring can be fastened in a simple way to a
grinding machine by means of a fastening device, such as is
described, for example, in EP 911 116.
[0014] In an alternative exemplary embodiment, the carrying body is
designed as a disk. One advantage of this construction is that the
disk can be fastened directly to the grinding machine.
[0015] In a preferred embodiment, the abrasive is clamped on the
carrying body by means of a clamping device. The sheetlike flexible
abrasive is curved around the curvature of the circumferential
surface of the carrying body and is clamped laterally. Such a
clamping device reliably ensures that the abrasive does not come
loose even at high loads.
[0016] Moreover, the clamping device may be designed as a holding
means for fastening the grinding wheel to a grinding machine. The
clamping device in this case serves at the same time for holding
the grinding wheel and for fastening the abrasive.
[0017] According to an alternative exemplary embodiment, the
abrasive is glued to the carrying body. Gluing is simpler than
clamping, since a specific clamping device can be dispensed with.
Of course, gluing can also be combined with clamping. For this
purpose, the abrasive is glued to the carrying body in a first
step. To increase the resistance, the abrasive is at the same time
also clamped.
[0018] In a further exemplary embodiment, the abrasive is formed
from segments which are arranged next to one another on the
carrying body so as to overlap in the circumferential direction.
The abrasive is fastened to one side of a carrying body in a
similar way to EP 911 116. In contrast to EP 911 116, however, the
carrying body has a curved outer surface, over which the abrasive
is applied in a curved manner. Individual segments can be adapted
to the curvature of the circumferential surface in a particularly
simple way.
[0019] The segments are particularly advantageously of
almond-shaped design. In this connection, "almond-shaped" means
that the segments have rounded side edges which narrow toward both
ends of the segment. This shape reduces the thickening of the layer
consisting of the segments which is caused by the overlapping.
[0020] According to an alternative exemplary embodiment, the
abrasive is designed as a belt which, as seen in the
circumferential direction, is wound in coils on the carrying body
designed as a ring. This type of fastening is particularly
advantageous, because the belt, as it were, fastens itself to the
carrier on account of the coils. Since only a one-piece abrasive is
applied, the outlay in terms of production is reduced.
[0021] The overlapping of the segments or of the coils is in this
case advantageously designed in such a way that the distance of the
front end of the segments or coils, as seen in the direction of
rotation, from the axis of rotation is greater than the distance of
the rear end. Overlapping of this type leads to an advantageous
self-renewing effect and consequently to an increase in service
lives. During operation, the rear end of the segments or coils
which is furthest on the outside is removed first.
[0022] According to a further exemplary embodiment, the abrasive is
designed as a belt which, as seen in the circumferential direction,
is applied to the circumferential surface. The belt is applied as a
closed belt to the circumferential surface and is bent around along
its side edges toward the surfaces of the carrying body. The
advantage of this exemplary design is that, in contrast to
overlaps, the grinding surface is essentially flat, that is to say
has no steps.
[0023] In order to make it easier for the edges of the closed belt
to be folded round, the belt may be provided along its edges with
indentations or cutouts. The segments formed between indentations
or cutouts can be folded onto the surfaces of the carrying body and
at the same time slightly overlap one another. A corrugation of the
sheetlike abrasive is thereby avoided.
[0024] According to a further exemplary embodiment, the abrasive in
the form of abrasive material (abrasive grain) is glued directly to
the surface of the carrying body by means of a binder. Fastening
and deformation of abrasive on a substrate are therefore
unnecessary.
[0025] The radius of curvature of the circumferential surface is
typically adapted to the curved surface to be ground. The radius is
preferably between 3 mm and 8 mm. The carrying body of the grinding
wheel is advantageously formed from glass-fiber-reinforced plastic.
The abrasive can be glued especially permanently to such a carrying
body. It is also conceivable, however, in particular, to
manufacture a carrying body designed as a ring, for example, from
aluminum or from plastic. The curved portion of the circumferential
surface of the carrying body advantageously extends over an angle
of more than 180.degree., that is to say the carrying body has a
ringlike outer circumference. A particularly large actively usable
grinding surface is thereby made available.
[0026] The invention is explained in more detail below in exemplary
embodiments and with reference to the drawings in which:
[0027] FIG. 1 shows a section through a surface to be ground and
through part of a grinding wheel according to the invention,
[0028] FIG. 2 shows a top view of a first exemplary embodiment of a
grinding wheel according to the invention,
[0029] FIG. 3 shows a cross section through the exemplary
embodiment according to FIG. 2,
[0030] FIG. 4 shows an enlarged illustration of abrasives according
to the exemplary embodiment from FIG. 2,
[0031] FIG. 5 shows a top view of a second exemplary embodiment of
the invention,
[0032] FIG. 6 shows a cross section through a grinding wheel
according to the exemplary embodiment from FIG. 5,
[0033] FIG. 7 shows a top view of an intermediate product for the
production of a grinding wheel according to the invention,
[0034] FIG. 8 shows a cross section through part of the
intermediate product according to FIG. 7 and a grinding wheel
produced from it,
[0035] FIG. 9 shows a top view of a third exemplary embodiment of
the grinding wheel according to the invention,
[0036] FIG. 10 shows a top view of the abrasive for a grinding
wheel according to the exemplary embodiment from FIG. 9, and
[0037] FIG. 11 shows a cross section through a fourth exemplary
embodiment of a grinding wheel.
[0038] FIG. 1 shows schematically the use of a grinding wheel 1
according to the invention in cross section. The grinding wheel 1
serves, for example, for the grinding of radii into the surface O
of a weld seam S which, for example, joins together two metal parts
M1, M2.
[0039] A grinding wheel 1 is fastened rotatably about an axis A.
The grinding wheel 1 has a carrying body which, according to the
following exemplary embodiments, may be designed as a ring 2 or as
a disk 12. FIG. 1 shows a section through the grinding wheel 1
along a radial plane R (see FIG. 2). Planes running through the
axis A are designated as radial planes. The carrying body of the
grinding wheel 1 has a circumferential surface 4. This
circumferential surface 4 is the surface defining the circumference
of the grinding wheel 1. The circumferential surface 4 is curved
convexly, in section, relative to the radial plane R. In the region
of the circumferential surface 4, the carrying body of the grinding
wheel 1 is provided with an abrasive which, according to the
following exemplary embodiments, may be designed as a segment or as
a belt or as abrasive grain applied to the carrying body by means
of a binder. On account of the convex curvature of the
circumferential surface 4, the abrasive, for example a segment 3,
applied to the circumferential surface 4 also acquires a convex
shape. The radius can be ground into the surface O of the weld
location S by means of the curved abrasive.
[0040] A first exemplary embodiment of the grinding wheel according
to the invention is shown in FIGS. 2 to 4. FIG. 2 shows a top view
of the grinding wheel 1. The grinding wheel 1 according to this
exemplary embodiment has a carrying body designed as a ring 2. The
ring 2 is formed from aluminum, steel or nylon or from a
glass-fiber-reinforced plastic. Along the outer circumferential
surface 4, the ring 2 is curved convexly in a radial sectional
plane R. Mutually overlapping segments 3 lying next to one another
and consisting of a flexible abrasive are arranged on the ring 2.
Typically, abrasive segments with a carrying material consisting of
fabric (cotton or polyester), on which desired abrasive grain is
held by means of a binder, are used. Segments 3 are glued to the
underside and top side of the ring 2 by means of an adhesive, for
example a polyurethane adhesive. In addition, the segments 3 are
clamped by means of a clamping device (see FIG. 3). The clamping
device consists of an upper part 5 and a lower part 6 which are
held together, for example, by means of screws 10 and thus clamp
the ring 2 together with the segments 3. Moreover, the clamping
device consisting of the parts 5, 6 may be provided with a holding
device 7 (illustrated by broken lines), by means of which the
grinding wheel 1 can be fastened to a grinding machine (not
illustrated).
[0041] The overlapping of the segments 3 is selected such that the
distance d of the front end 8 of the segments 3 in the direction of
rotation D, from the axis of rotation A of the grinding wheel l is
shorter than the distance of the rear end 9 of the segment 3, as
seen in the direction of rotation D, from the axis of rotation A.
This results in a softer grinding action. At the same time, during
operation the rear end 9 is removed, so that the grinding wheel 1
is self-renewing.
[0042] As shown in FIG. 3 the circumferential surface 4 is
provided, in a radial sectional plane R, with a radius of curvature
r. The circumferential surface 4 does not need to run exactly along
a circle, that is to say the radius of curvature of the
circumferential surface is not constant. The radius of curvature r
is selected according to the type of grinding location to be
treated. It is typically 3 mm to 8 mm.
[0043] When the grinding wheel 1 is worn away, the clamping device
consisting of the parts 5, 6 can be released and the ring 2
replaced. Owing to the clamping device, it is not necessary for the
holding device 7 connected to the clamping device 5, 6 to be
replaced.
[0044] FIG. 4 shows a preferred shape of the segments 3. The
segments 3 are of almond-shaped design. That is to say, the
segments have the greatest width in a middle region 15. The middle
region 15 bears against the ring 2 along an outer circumferential
line 16. The segments 3 narrow away from the center line 15, the
front end 8 and the rear end 9 being of curved design. This shape
of the segments 3 takes into account the desired curvature of the
segments 3. The problem of thickenings due to additional material
in the region of the fastening of the segments 3 on the ring 2 is
thereby avoided.
[0045] FIGS. 5 and 6 show an alternative exemplary embodiment of
the grinding wheel 1 according to the invention. As in FIGS. 2 to
4, the carrying body is designed as a ring 2. In contrast to the
preceding exemplary embodiment, the abrasive is designed as a belt
13 which is wound in coils 14 around the ring 2. The coils 14 are
arranged, in a similar way to the segments 3, such that the
distance of the front end 8 of the coils, as seen in the direction
of rotation, from the axis of rotation A is greater than the
distance of the rear end 9 of the coils 14. One advantage of the
winding is that individual segments do not have to be fastened to
the ring. A gluing of the abrasive to the ring 2 may be dispensed
with. The clamping device, evident in FIG. 6, consisting of an
upper and a lower part 5, 6 serves for pressing the grinding belt
13 onto the ring 2. The ring 2 is provided on its top side and
underside with a concave pressing region 17. The parts 5, 6 press
the grinding belt 13 into the concave region 17. This leads to a
tensioning of the grinding belt 13 in the region of the curved
circumferential surface 4.
[0046] FIG. 7 shows a top view of an intermediate product of a
grinding wheel which is constructed in a similar way to the
exemplary embodiment according to FIGS. 2 to 4. In contrast to the
exemplary embodiment according to FIGS. 2 to 4, according to FIG. 7
the carrying body is designed as a continuous disk 12. The disk 12
consists, for example, of glass-fiber-reinforced plastic. To
produce a grinding wheel according to this exemplary embodiment,
first, segments 3 are glued to a surface of the disk 12, so that an
inner end 11a is glued to the surface and an outer end 11b of the
segments projects (see the cross section in FIG. 8) beyond the
outer circumferential line 16 of the disk 12 to an extent such that
the projecting end 11b can subsequently be curved downward and
likewise be glued to the underside 12 of the disk 12. In this case,
the segment 3 assumes the convex shape of the circumferential
surface 4.
[0047] Of course, a grinding wheel according to FIG. 2 to 4 having
a ring-shaped carrying body can also be produced by means of the
production method thus illustrated.
[0048] FIGS. 9 and 10 show a further exemplary embodiment of the
invention. The carrying body is designed as a ring 2 in a similar
way to the exemplary embodiment according to FIG. 2 to 4. The
abrasive is designed as a belt 23 which is applied to the ring 2 in
the circumferential direction U along the outer circumferential
line 16. The belt 23 is intrinsically flat. So that the belt 23
acquires a curved surface, the edges 24 of the belt 23 are folded
onto the top side and underside of the wheel 2 and fastened, for
example glued and/or clamped, thereto. So that the belt 23 is not
corrugated when the edges 24 are folded round, the belt is provided
with indentations 25 extending from the edges 24 toward the middle
26 of the belt 23. The belt 23 overlaps itself in the region of the
indentations 25 on the top side and underside of the wheel 2 (see
FIG. 9). FIG. 10 shows a top view of a detail of the belt 23. The
middle 26 of the belt is laid onto the wheel 2 along the outer
circumferential line 16. FIG. 10 illustrates cutouts 25. The size
of the cutouts 25 may be selected according to the degree of
curvature. Indentations are also conceivable in which no material
is removed from the belt 23. The exemplary embodiment according to
FIGS. 9 and 10 can be implemented both with a carrying body as a
ring 2 and with a disk-shaped carrying body 12. The grinding belt
23 is a conventional grinding belt. The grinding belt can be glued
along the outer circumferential line 16 and to the top side and
underside of the carrying body and/or be clamped by means of a
clamping device in a similar way to the preceding exemplary
embodiments.
[0049] FIG. 11 shows a cross section through a fourth exemplary
embodiment of the invention. A carrying body designed as a ring 2
is formed as an injection molding, in which the ends 11a, 11b of
the segments 3 are anchored. Such anchoring is, of course, also
conceivable in connection with a continuous disk, according to the
exemplary embodiment in FIG. 7 and 8, and with a belt applied in
the circumferential direction, according to FIGS. 9 and 10. The
parts of the fastening device 5, 6 for all the exemplary
embodiments shown can be manufactured, for example, from aluminum.
Plastic injection moldings may, however, also be envisaged.
[0050] In the exemplary embodiments according to FIGS. 1, 3, 6 and
11, the curved circumferential surface extends over an angle .beta.
of more than 180.degree.. That is to say, a circumferential portion
of at least 180.degree. can be used for grinding. The carrying body
has in this case a region of greatest thickness in the axial
direction. The thickness of the carrying body decreases radially
inward from this region, so that a drop-shaped cross section is
obtained. The abrasive is applied to the carrying body radially
inward over and beyond the region of greatest thickness.
[0051] According to a further exemplary embodiment not illustrated
in the figures, the abrasive is applied, without substrate,
directly to the carrying body, for example a ring, as shown in FIG.
2 and 3. For this purpose, abrasive grain is applied by means of a
binder (for example, epoxy resin) to the surface of the ring 2 (for
example, consisting of aluminum, steel or plastic).
* * * * *