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Claims  |
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We claim:
1. A portable grinder comprising:
a housing;
a grinding or polishing tool having a first working surface with a
plurality of side edges meeting to form at least one corner region having
an angle less than 90.degree.; and
drive means, supported in said housing, for pivotably oscillating said
grinding tool about a pivot axis, said pivot axis intersecting said
grinding tool in a central region thereof; and wherein
regions of said grinding tool along said side edges are exposed such that
the side edge regions can work along an inside longitudinal edge of a
second surface along the junction of said second surface and a third
surface angled thereto, with one of said side edges engaging said third
surface.
2. A portable grinder as set forth in claim 1 wherein said pivot axis is at
the center of said tool.
3. A portable grinder as set forth in claim 1 wherein said drive means
includes a drive shaft supporting said tool to pivot about said pivot
axis.
4. A portable grinder as set forth in claim 1 wherein said working surface
of said tool is polygonal.
5. A portable grinder as set forth in claim 4 wherein said working surface
of said tool is triangular.
6. A portable grinder as set forth in claim 1 wherein said side edges
adjoining said corner region are convex.
7. A portable grinder as set forth in claim 1 wherein said side edges in
said corner region are straight.
8. A portable grinder as set forth in claim 1 wherein said angle at said
corner region is approximately 80.degree..
9. A portable grinder as set forth in claim 1 wherein said housing is
elongated and has a longitudinal axis which intersects said pivot axis.
10. A portable grinder as set forth in claim 9 wherein said housing extends
laterally rearwardly of said tool and said corner of said working surface
is located in a forward region of said tool.
11. A portable grinder as set forth in claim 10 wherein said corner of said
working surface is located approximately opposite the rearwardly extending
portion of said housing with respect to said pivot axis.
12. A portable grinder as set forth in claim 10 wherein said corner of said
working surface protrudes beyond said housing.
13. A portable grinder as set forth in claim 3 wherein said housing
comprises a motor subhousing and an adjoining gear subhousing, and said
drive shaft is mounted within said gear subhousing.
14. A portable grinder as set forth in claim 1 wherein said tool oscillates
at a frequency between approximately 10,000 and 25,000 times per minute.
15. A portable grinder as set forth in claim 1 wherein said tool pivots
within an angle between approximately 0.5.degree. and 7.degree..
16. A portable grinder as set forth in claim 3 wherein said drive means
further includes a rotating motor and gear means interposed between said
rotating motor and said drive shaft for converting rotational motion of
said rotating motor into oscillating pivotal motion for driving said drive
shaft and said tool.
17. A portable grinder as set forth in claim 3 wherein said tool is
positively connected with said drive shaft.
18. A portable grinder as set forth in claim 17 wherein said drive shaft
has a polygonal cross-section and said tool has a socket of corresponding
cross-section adapted to receive said drive shaft.
19. A portable grinder as set forth in claim 3 wherein said tool is
supported eccentrically in relation to said drive shaft and has a
substantially strip-shaped configuration.
20. A portable grinder as set forth in claim 19 wherein only side edge
regions of said tool comprise a grinding or polishing surface.
21. A portable grinder as set forth in claim 20 wherein said side edge
regions of said tool are angled relative to the central region of said
tool.
22. A portable grinder as set forth in claim 3 wherein
said tool has an aperture, and said drive shaft has a threaded end which
extends into said aperture, said drive shaft also having an annular flange
between the threaded end and an adjacent non-threaded portion, and further
comprising
a threaded element threadably received on said threaded end of said drive
shaft and clamping said tool between said threaded end and said annular
flange.
23. A portable grinder as set forth in claim 22 further comprising a
compression spring inserted between said tool and either said threaded end
or said annular flange of said drive shaft.
24. A portable grinder as set forth in claim 1 wherein said tool comprises
a grinding or polishing element forming said working surface, and a
supporting member supporting said grinding or polishing element, said
grinding or polishing element being removably connected to said supporting
member.
25. A portable grinder as set forth in claim 24 wherein said grinding or
polishing element is flexible, and said supporting member is stiff.
26. A portable grinder as set forth in claim 25 wherein said grinding or
polishing element has recesses on said working surface.
27. A portable grinder as set forth in claim 26 wherein said tool includes
a suction port and said recesses in said working surface join with said
suction port.
28. A portable grinder as set forth in claim 27 wherein said drive means
includes a motor, and further comprising a suction fan driven by said
motor and communicating with said suction port.
29. A portable grinder as set forth in claim 27 wherein said drive means
includes a drive shaft supporting said tool to pivot about said pivot
axis, said drive shaft being hollow and communicating with said suction
port.
30. A portable grinder as set forth in claim 27 further comprising a dust
collecting container in communication with said suction port.
31. A portable grinder as set forth in claim 24 wherein said grinding or
polishing element comprises a foamed material.
32. A portable grinder as set forth in claim 24 wherein said grinding or
polishing element comprises felt.
33. A portable grinder as set forth in claim 24 wherein said working
surface of said grinding or polishing element comprises a hook and loop
fastening material.
34. A portable grinder as set forth in claim 25 wherein an edge region of
said grinding or polishing element protrudes laterally beyond said
supporting member, and further comprising spring means for biasing said
edge region toward a surface to be worked upon.
35. A portable grinder as set forth in claim 34 further comprising a rivet
connecting said spring means to said supporting member, a head of said
rivet pointing in the direction of said surface to be worked upon being
accommodated in a recess in said grinding or polishing element.
36. Grinding tool for a grinder with drive means for pivotably oscillating
said grinding tool about a pivot axis, comprising a working surface with a
plurality of side edges meeting to form at least one corner having an
angle of less than 90.degree., wherein regions along said side edges are
exposed such that the side edge regions can work along an inside edge
along the junction of two surfaces angled relative to each other.
37. Grinding tool according to claim 36, characterized in that the grinding
tool comprises a polygonal working or front surface.
38. Grinding tool according to claim 37, characterized in that the front
surface is in the form of a triangular surface.
39. Grinding tool according to claim 36, characterized in that the free
side edges which are suitable for grinding are of convex outwardly bent
configuration adjoining the region of the corner.
40. Grinding tool according to claim 36, characterized iin that th side
edges are of straight-line configuration in the region of the corner.
41. Grinding tool according to claim 36, characterized in that the angle in
the corner is approximately 80.degree..
42. Grinding tool according to claim 36, further comprising means for
mounting said grinding tool on said drive means disposed in a central
region of said grinding tool.
43. Grinding tool for a grinder with drive means for pivotably oscillating
said grinding tool about a pivot axis, comprising a working surface with a
plurality of side edges meeting to form at least one corner region and
regions along said side edges being exposed such that the side edge
regions can work along an inside edge along the junction of two surfaces
angled relative to each other and having a convex outwardly bent
configuration adjoining the region of the corner.
44. Grinding tool as set forth in claim 43 wherein the grinding tool
comprises a polygonal working or front surface.
45. Grinding tool as set forth in claim 44 wherein the front surface is in
the form of a triangular surface.
46. Grinding tool as set forth in claim 43 wherein the free side edges
which are suitable for grinding meet the corner region at an angle of less
than 90.degree..
47. Grinding tool as set forth in claim 43 wherein the side edges are of
straight-line configuration in the region of the corner.
48. Grinding tool as set forth in claim 46 wherein the angle in the corner
is approximately 80.degree..
49. Grinding tool as set forth in claim 43 wherein means for mounting said
grinding tool on said drive means are arranged in a central region of said
grinding tool.
50. A portable grinder comprising:
a housing;
a grinding or polishing tool having a first working surface with a
plurality of side edges meeting to form at least one corner region; and
drive means, supported in said housing, for pivotably oscillating said
grinding tool about a pivot axis, said pivot axis intersecting said
grinding tool in a central region thereof;
and wherein regions of said grinding tool along said side edges are exposed
such that the side edge regions can work along an inside longitudinal edge
along the junction of two surfaces angled relative to each other and
having a convex outwardly bent configuration adjoining said corner region.
51. A portable grinder as set forth in claim 50 wherein said pivot axis is
at the center of said tool.
52. A portable grinder as set forth in claim 50 wherein said drive means
includes a drive shaft supporting said tool to pivot about said pivot
axis.
53. A portable grinder as set forth in claim 50 wherein said working
surface of said tool is polygonal.
54. A portable grinder as set forth in claim 53 wherein said working
surface of said tool is triangular.
55. A portable grinder as set forth in claim 50 wherein said side edges
meet in said corner region at an angle of less than 90.degree..
56. A portable grinder as set forth in claim 55 wherein said angle between
said side edges in said corner region is approximately 80.degree..
57. A portable grinder as set forth in claim 55 wherein said side edges in
said corner region are straight.
58. A portable grinder as set forth in claim 50 wherein said housing is
elongated and has a longitudinal axis which intersects said pivot axis.
59. A portable grinder as set forth in claim 58 wherein said housing
extends laterally rearwardly of said tool and said corner of said working
surface is located in a forward region of said tool.
60. A portable grinder as set forth in claim 59 wherein said corner of said
working surface is located approximately opposite the rearwardly extending
portion of said housing with respect to said pivot axis.
61. A portable grinder as set forth in claim 50 wherein said corner of said
working surface protrudes beyond said housing.
62. A portable grinder comprising:
a housing;
a grinding or polishing tool having a first working surface with a
plurality of side edges;
regions of said grinding tool along said side edges being exposed such that
the side edge regions can work along an inside longitudinal edge along the
junction of two surfaces angled relative to each other; and
drive means, supported in said housing, for pivotably oscillating said
grinding tool about a pivot axis at a pivoting frequency of approximately
10,000 to 25,000 oscillations per minute and a pivot angle of
approximately 0.5.degree. to 7.degree., said pivot axis intersecting said
grinding tool in a central region thereof.
63. A portable grinder as set forth in claim 62 wherein said pivot axis is
at the center of said tool.
64. A portable grinder as set forth in claim 62 wherein said drive means
includes a drive shaft supporting said tool to pivot about said pivot
axis.
65. A portable grinder as set forth in claim 62 wherein said working
surface of said tool is polygonal.
66. A portable grinder as set forth in claim 65 wherein said working
surface of said tool is triangular.
67. A portable grinder as set forth in claim 64 wherein said tool is
positively connected with said drive shaft.
68. A portable grinder as set forth in claim 67 wherein said drive shaft
has a polygonal cross-section and said tool has a socket of corresponding
cross-section adapted to receive said drive shaft.
69. A portable grinder as set forth in claim 64 wherein said tool is
supported eccentrically in relation to said drive shaft and has a
substantially strip-shaped configuration.
70. A portable grinder as set forth in claim 69 wherein only side edge
regions of said tool comprises a grinding or polishing surface.
71. A portable grinder as set forth in claim 70 wherein said side edge
regions of said tool are angled relative to the central region of said
tool.
72. A portable grinder as set forth in claim 64 wherein said tool has an
aperture, and said drive shaft has a threaded end which extends into said
aperture, said drive shaft also having an annular flange between the
threaded end and an adjacent non-threaded portion, and further comprising
a threaded element threadably received on said threaded end of said drive
shaft and clamping said tool between said threaded end and said annular
flange.
73. A portable grinder as set forth in claim 72 further comprising a
compression spring inserted between said tool and either said threaded end
or said annular flange of said drive shaft.
74. A portable grinder as set forth in claim 62 wherein said tool comprises
a grinding or polishing element forming said working surface, and a
supporting member supporting said grinding or polishing element, said
grinding or polishing element being removably connected to said supporting
member.
75. A portable grinder as set forth in claim 74 wherein said grinding or
polishing element is flexible, and said supporting member is stiff.
76. A portable grinder as set forth in claim 75 wherein said grinding or
polishing element has recesses on said working surface.
77. A portable grinder as set forth in claim 76 wherein said tool includes
a suction port and said recesses in said working surface join with said
suction port.
78. A portable grinder as set forth in claim 77 wherein said drive means
includes a motor, and further comprising a suction fan driven by said
motor and communicating with said suction port.
79. A portable grinder as set forth in claim 77 wherein said drive means
includes a drive shaft supporting said tool to pivot about said pivot
axis, said drive shaft being hollow and communicating with said suction
port.
80. A portable grinder as set forth in claim 77 further comprising a dust
collecting container in communication with said suction port.
81. A portable grinder as set forth in claim 74 wherein said grinding or
polishing element comprises a foamed material.
82. A portable grinder as set forth in claim 74 wherein said grinding or
polishing element comprises felt.
83. A portable grinder as set forth in claim 74 wherein said working
surface of said grinding or polishing element comprises a hook and loop
fastening material.
84. A portable grinder as set forth in claim 75 wherein an edge region of
said grinding or polishing element protrudes laterally beyond said
supporting member, and further comprising spring means for biasing said
edge region toward a surface to be worked upon.
85. A portable grinder as set forth in claim 84 further comprising a rivet
connecting said spring means to said supporting member, a head of said
rivet pointing in the direction of said surface to be worked upon being
accommodated in a recess in said grinding or polishing element. |
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Claims |
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Description |
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The invention relates to a portable grinder with a drive motor and a
grinding or polishing tool oscillatingly driven by it. Such portable
grinders are known as so-called vibratory grinders and are widely
propagated. They serve, for example, to prepare a surface which is to be
subsequently coated with paint or the like. The oscillating plate is
driven by means of an electric motor and an interposed eccentric and it
usually carries an exchangeable abrasive sheet. The oscillatory motion is
either straight-line back and forth or orbital, i.e., in addition, a
transverse motion is superimposed on the back and forth motion. In all,
the oscillating plate executes a motion of the order of approximately one
centimeter which is at least oriented in the longitudinal direction. To
avoid damage, the edges at the ends of the oscillating plate must be kept
a sufficiently large distance away from further surfaces extending
transversely to the workpiece surface which is being worked upon. This is
particularly applicable if one of these surfaces is a pane of glass. Such
vibratory grinders are, therefore, not usable, or only to an inadequate
extent, to grind, for example, glass retaining ledges and inside edges
meeting at right angles on window frames. At any rate, grinding right into
the corners is not possible.
Apart from the above-mentioned portable grinders with an oscillatingly
driven grinding tool, there are also portable grinders with a rotating
grinding tool, for example, angle grinders or portable grinders with a
circulating grinding tool such as, for example, belt grinders. There are
also certain grinding operations, in particular, the grinding of inside
edges and inside surfaces which cannot be performed with these portable
grinders, or only with unsatisfactory results.
The object underlying the invention is, therefore, to so develop a portable
grinder of the kind described at the outset that it can be used to grind
surfaces right into converging inside edges or to carry out similar
grinding operations which are spatially difficult to perform.
To achieve this object, it is proposed, in accordance with the invention,
that the portable grinder according to the preamble of claim 1 be designed
in accordance with the characterizing clause of this claim. The principle
of the oscillatingly driven grinding or polishing tool, which is
advantageous as such, is adhered to in this portable grinder. Instead of
the straight-line motion back and forth or the orbital, elliptic-type
grinding motion, the grinding or polishing tool of this portable grinder
executes a pivotal motion by oscillating about a fixed axis of the
apparatus, with the pivot angle being kept relatively small, but the
frequency during operation being high. This different type of oscillating
motion of the grinding or polishing tool enables the tools to be designed
in a completely new way, particularly as far as the working surface of the
grinding or polishing tool is concerned. This does, of course, not exclude
use of grinding or polishing tools of conventional shape.
Further advantageous embodiments are the subject of the subclaims. Within
the scope of the inventive solution, it should be emphasized, in
particular, that in one embodiment the grinding or polishing tool may be
designed to comprise a corner region tapering to a point, with its side
edges including an angle of less than 90 degrees. Hence this corner region
preferably enables grinding of corners, which is not possible with the
hitherto known grinding tools.
The grinding tool further comprises free side edges adjoining the corner.
It is, therefore, also possible to grind inside longitudinal edges with
such an inventive grinding tool as the grinding tool can be operated with
the side edges adjoining the corner resting against these inside
longitudinal edges.
In accordance with the invention, it is highly advantageous for the side
edges adjoining the corner to be of convex outwardly bent configuration
since such convex bending of the side edges results in the grinding tool
resting only in an outermost region of the curve against the inside
longitudinal edge and executing with it during its oscillatory motions a
movement oriented parallel to this inside longitudinal edge. It can,
therefore, be guided along this inside longitudinal edge without being
struck away from it, whereas with a straight side edge, the front and rear
regions of the side edge would strike perpendicularly against the inside
longitudinal edge during an oscillatory motion and hence would also
accelerate the grinding tool away from this inside longitudinal edge.
A particularly advantageous further development of the above-described
embodiment is obtained, in accordance with the invention, if, in addition,
the pivot axis intersects the grinding tool in a central region as the
convex side surfaces can then be designed in accordance with the invention
such that in their outermost region they do not execute a radial motion
with respect to the pivot axis, but merely a motion extending
perpendicularly to the radial direction, which makes the grinding tool
rest extremely smoothly against an inside longitudinal edge. A further
advantage of a pivot axis arranged in a central region of the grinding
tool is to be seen in the fact that imbalances and hence vibrations of the
entire portable grinder can be avoided.
However, by choosing, for example, a two-edged or preferably a three-edged
shape for the grinding or polishing tool, one obtains a grinding or
polishing tool with an end region which tapers to a point and thereby also
enables grinding of minute surfaces and parts of surfaces. With it, one
can also reach into inside edges which meet spatially at right angles, for
example, in the corner regions of the panes when old paint is being rubbed
down from window frames. By virtue of the high frequency, a high removal
rate is achieved, while, in contrast to the vibratory grinder, the minimal
pivot angle causes only a minimal deflection motion of the grinding or
polishing tool, more particularly, transversely to the fixed axis of the
apparatus. With a certain pivot angle, this deflection is, of course, all
the smaller, the smaller the distance of the free end of the grinding or
polishing tool from this fixed axis of the apparatus. In this way, the
deflection of the tool during the oscillatory motion can be influenced by
using differently sized grinding or polishing tools. It is readily
possible to keep the deflection so small that it is hardly perceivable
with the naked eye. One then has the impression that the grinding or
polishing tool is not moving at all although it is, of course, performing
its work correctly. In this case, neat work can, in fact, be performed
right into the inside corner.
When mention is made herein of an axis fixed in relation to the apparatus,
this primarily relates to the geometrical axis about which the grinding or
polishing tool is pivoted back and forth in the direction of rotation. It
will be readily understood that this geometrical axis need not necessarily
be arranged centrally in relation to the working surface of the grinding
or polishing tool. For example, with a two-edged configuration or the
like, a geometrical axis which is offset in the longitudinal direction of
the tool has the advantage that oscillation amplitudes of different range
are obtained at the two tool ends protruding in the direction of opposite
sides. Expediently, however, a pivot of, for example, peg-shaped
configuration is provided, on which the grinding or polishing tool is held
and whose geometrical axis extends through the apex of the pivot angle.
The oscillating pivotal motion of the grinding or polishing tool can be
achieved in a manner known per se with a conventional drive motor, for
example, an electric motor and an accentric driven by it. The drive is,
therefore, not illustrated or described in greater detail. The eccentric
transfers its rotational motion to a rotatably mounted rocker whose
geometrical axis of rotation may at the same time be the geometrical axis
for the angular oscillating motion of the grinding or polishing tool. The
eccentric engages the end remote from the above-mentioned bearing axis of
the rocker, whose longitudinal axis in particular runs approximately
parallel to the longitudinal axis of the drive shaft of the eccentric or
the drive shaft of the motor. Instead of an electric drive motor, it is,
of course, also possible to use any other motor by means of which, for
example, such a rocker or a comparable element can be driven in a back and
forth pivoting manner.
The previously known vibratory grinders operate with a frequency of the
order of ten thousand oscillations per minute. It is expedient to also
allow the grinding or polishing tool of the inventive portable grinder to
oscillate at least in this order of magnitude. Hence in a preferred
embodiment of the invention, the pivoting frequency of the grinding or
polishing tool is approximately ten thousand to twenty-five thousand
oscillations per minute. This means that with this tool one can go
substantially higher with the frequency than in the known prior art. As a
rule, however, particularly if the frequency is electronically controlled,
one will go to the upper limit of this range with smaller grinding or
polishing tools rather than with comparatively larger ones. Also, the high
frequencies will be primarily used for polishing. Accordingly, with this
portable grinder it is readily possible to polish away, for example,
scratches on sensitive windshields which can be caused by the windshield
wiper of an automotive vehicle being operated on a dry windshield covered
with a layer of dust or grains of sand.
In order not to lose the advantages of this novel type of grinding, the
pivot angle should not exceed a certain maximum value with respect to its
maximum deflection. In principle, there are no limits in the downward
direction. Seen from this viewpoint, it is considered expedient to keep
the pivot angle of the grinding or polishing tool within a range of
approximately 0.5 degrees to 7 degrees. It is quite conceivable to make
the pivot angle alterable, but this involves a certain expenditure.
A particularly preferred variant of the invention is characterized in that
a drive shaft comprising or forming the fixed axis of the apparatus is
oscillatingly drivable in the direction of rotation by a motor and an
interposed gearing. Accordingly, the output shaft of the motor executes a
rotational motion, in the usual manner, and, as previously mentioned, it
is preferably a high-speed electric motor. The gearing converts this
rotational motion into a reciprocating angular pivotal motion of the
above-mentioned frequency.
A further embodiment of the invention consists in the grinding or polishing
tool being positively connected with the drive shaft, with the drive shaft
being, in particular, of polygonal or star-shaped cross-section and the
tool comprising a socket or an opening of corresponding cross-section. In
this way, a positive connection of the grinding or polishing tool with the
oscillating drive shaft is achieved which, on the one hand, can contend
with the stresses which occur and, on the other hand, enables simple and
quick exchange of the tool.
In an axially symmetrical or centrally symmetrical design, the grinding or
polishing tool is preferably arranged concentrically with the drive shaft.
As the drawings show, it is, above all, a question of a grinding or
polishing tool with a polygonal shape, for example, a triangular or
quadrangular shape, with the longitudinal edges extending in a straight
line or being concave or convex. In accordance with FIG. 7 of the
drawings, quite special edge shapes are also readily possible.
Accordingly, the grinding or polishing tool very advantageously exhibits a
non-circular, in particular, approximately polygonal working surface.
Another variant of the invention is characterized in that the grinding or
polishing tool is arranged eccentrically in relation to the drive shaft
and, in particular, is of substantially bar-shaped or strip-shaped
configuration. This tool is suited, above all, for working on small and
minute surfaces or on inside edges and inside corners.
Special operations can be carried out with a grinding or polishing tool
which is advantageously characterized in that only the free end region of
this tool comprises a grinding or polishing surface. In a further
development of the invention, the free end or the free end region is
angled and only the angled part comprises a grinding or polishing surface,
as is apparent from FIG. 6 of the drawings. Grinding and polishing
operations for which no hand tool has existed hitherto, can be
mechanically performed with this tool.
In a further particularly advantageous embodiment of the inventive portable
grinder, the housing extends substantially laterally in the direction away
from the pivot axis, i.e., the pivot axis is, for example, located in a
front gearing section of this housing and the latter then extends in one
direction away from the pivot axis. This has the great advantage,
particularly when working on corners, that the grinding tool can be easily
introduced into any corners with a part thereof which is located opposite
the housing with respect to the pivot axis. Advantageously, the corner
region of the grinding tool having an angle less than 90 degrees should
then be arranged in the region of the grinding tool located opposite the
housing in order that the operator has a good view of it and introduction
of this corner region into a corner is not impeded by the housing itself
as it extends in the opposite direction with respect to the pivot axis.
In a last embodiment lying within the scope of the inventive solution, it
is of advantage, in a further development of the above-mentioned
embodiments, for the housing to comprise a longitudinal axis which
includes approximately a right angle with the pivot axis. As a rule, in
such an embodiment, the longitudinal axis of the housing will coincide
with the axis of rotation of the rotating motor. Hence the axis of
rotation of the rotating motor will likewise be approximately at a right
angle to the pivot axis. The advantage of such an embodiment is that a
particularly simple and advantageous design of the gearing which converts
the rotating motion into an oscillating motion is possible.
This embodiment, furthermore, has the advantage that the housing, in
particular, the part of the housing accommodating the rotating motor does
not impede working in a corner since it is located approximately opposite
the corner region of the grinding tool and hence awards the operator an
optimal view thereof.
Finally, in accordance with the invention, it is particularly advantageous
for the housing containing the rotating motor to be simultaneously
designed as a handle for the operator.
Further configurations and advantages of the inventive portable grinder are
apparent from the following description of various embodiments.
These embodiments are illustrated in the drawings, in which:
FIG. 1 is a perspective, partly broken-off view from below of a first
variant of the invention;
FIG. 2 is a plan view of the working surface of a grinding and polishing
tool which differs from the illustration in FIG. 1;
FIG. 3 is a sectional view taken on line III--III of FIG. 2 in conjunction
with a broken-off and longitudinal sectional illustration of the portable
grinder of FIG. 1;
FIG. 4 is a vertical longitudinal sectional view of a third embodiment of
the tool;
FIG. 5 is a view from below of the tool of FIG. 4;
FIG. 6 is a plan view of a fourth variant of the grinding and polishing
tool;
FIG. 7 is yet another view from below of a fifth embodiment of the grinding
and polishing tool;
FIG. 8 is a view corresponding to FIG. 3 of the tool of FIG. 7;
FIG. 9 is a view from below of a sixth variant of a grinding and polishing
tool;
FIG. 10 is a sectional view taken on line X--X of FIG. 9;
FIG. 11 is a plan view of the tool of FIG. 9.
The grinder illustrated in FIG. 1 is provided with a motor 1 accommodated
in the housing. In lieu of the preferably provided electric motor, a
different drive, for example, a pneumatic one is conceivable. Adjoining
the motor 1 is a gearing 2 which is likewise accommodated in the housing.
In the gearing 2, the rotational motion of the electric motor is converted
into an oscillating motion of a grinding or polishing tool 3. More
specifically, the grinding or polishing tool performs a rotational motion
back and forth about the fixed geometrical axis 29 of the apparatus. The
angle of rotation is preferably of the order of 0.5 degrees to 7 degrees
and the frequency is, in particular, approximately ten thousand to
twenty-five thousand oscillations per minute.
In accordance with FIG. 3, the grinding and polishing tool 3, referred to
hereinafter for simplicity merely as "tool 3", which should not be
construed as a limitation, is connected, in particular, releasably, with
the drive shaft 4 which is the output shaft of the gearing. Hence its
geometrical axis 29 is a pivot fixed in relation to the apparatus, about
which the tool 3 oscillates.
In FIG. 1, the tool 3 comprises an approximately square-shaped working
surface 5. In FIG. 2, the tool 3 is of triangular shape. With the shape
shown in FIG. 2 one can reach better into corners which taper to a point.
Further polygonal shapes are also conceivable for the tool 3. In many
applications, a holder of elliptical shape may be used or the working
surface 5 may be of bulging configuration. In the drawings, the lines
joining the corner points are of arched configuration. However, to
facilitate working in corners, these lines can be straight in the corner
region.
An abrasive paper 6 or the like may, for example, be attached to the
working surface 5 of the tool 3. In accordance with the two picture halves
of FIG. 4, the abrasive paper 6 may be attached by hook and loop
fastening, by clips 7 or by self-adhesion.
The tool 3 consists of a dimensionally stable carrying or supporting member
and a grinding or polishing element 9. The latter comprises the working
surface 5 on its side facing away from the carrying or supporting member
8. An exchangeable and self-adhesive hook and loop fastening material 10
may be attached to the working surface 5 to hold an appropriate abrasive
paper or the like fixed. To connect the drive shaft 4 with the tool 3, the
carrying or supporting member 8 comprises an opening 11, in particular, a
polygonal hole. However, the hole may also be round. A bore 13 is provided
at the center of the grinding or polishing element 9 to enable a nut 12 to
be fixed with the carrying or supporting member on the drive shaft 4. In
this way, the drive shaft 4 can be inserted through the polygonal hole 11
until the shoulder 14 of the drive shaft 4 rests on the carrying or
supporting member 8. In the region protruding through the member 8, the
drive shaft 4 is designed in accordance with the polygonal hole 11 so as
to provide a positive connection between drive shaft 4 and carrying or
supporting member 8. The member 8 is pressed against the shoulder 14 by
the nut 12 which is screwed onto the thread 15 located at the end of the
drive shaft 4.
The drive shaft 4 comprises an, in particular, central bore 16 for the
removal of dust by suction. In order that the dust is not removable only
centrally, grooves 17 are machined in the radial direction from the bore
13, on the working surface 5 of the tool 3. To enable removal by suction
from the edge, also in the FIG. 4 embodiment, holes 18 are provided in the
abrasive paper or the like. There, the grinding dust is removed from the
edges of the holder via the grooves 17 and/or through the bore 13 and the
bore 16 of the drive shaft 4. These suction channels are connected, for
example, to a suction device, not depicted, via a hose 19 attached to the
gearing housing.
The variant shown in FIG. 6 is a grinding or polishing tool 20 which is
preferable for use under particularly confined space conditions. Its
clampin | | |
