U.S. patent application number 12/451028 was filed with the patent office on 2010-05-13 for portable grinder.
Invention is credited to Stephan Rieth.
Application Number | 20100120341 12/451028 |
Document ID | / |
Family ID | 39777551 |
Filed Date | 2010-05-13 |
United States Patent
Application |
20100120341 |
Kind Code |
A1 |
Rieth; Stephan |
May 13, 2010 |
PORTABLE GRINDER
Abstract
The invention relates to a portable grinder comprising a
grinding head (5) that can be placed against a workpiece (7) in a
grinding contact zone (26). According to the invention, a stop
(18-21) is disposed at a distance from the grinding contact zone
(26). Said stop (18-21) forms an axis of rotation (27) as a
swiveling axis for the grinding head (5) and as a pivot relative to
at least one handle (2,3).
Inventors: |
Rieth; Stephan; (St. Wendel,
DE) |
Correspondence
Address: |
FRIEDRICH KUEFFNER
317 MADISON AVENUE, SUITE 910
NEW YORK
NY
10017
US
|
Family ID: |
39777551 |
Appl. No.: |
12/451028 |
Filed: |
April 25, 2008 |
PCT Filed: |
April 25, 2008 |
PCT NO: |
PCT/DE2008/000724 |
371 Date: |
October 23, 2009 |
Current U.S.
Class: |
451/359 ;
451/344 |
Current CPC
Class: |
B24B 27/033 20130101;
B24B 23/028 20130101; B24B 23/005 20130101 |
Class at
Publication: |
451/359 ;
451/344 |
International
Class: |
B24B 23/02 20060101
B24B023/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 2007 |
DE |
10 2007 020 199.2 |
Claims
1. A portable grinder with a grinding head (5), the grinding
contact zone (26) of which can be placed against a workpiece (7),
comprising a stop (18-21), which is located a certain distance away
from the grinding contact zone (26) and which, when set against the
workpiece (7), forms a rotational axis (27), serving as a pivot
axis, for the grinding head (5) and as the fulcrum around which at
least one handle (2, 3) can rotate.
2. A portable grinding according to claim 1, wherein two handles
(2, 3), located a certain distance apart, are provided so that the
machine can be held and guided with both hands.
3. A portable grinder according to claim 2, wherein, in a
projection onto the workpiece, the grinding head (5) and/or the
stop (18-21) is located between the handles (2, 3).
4. A portable grinder according to claim 1, wherein the stop is a
guide stop (18-21), which makes it possible for the machine to be
pressed against the workpiece (7) without the danger of tipping in
the direction of the pivot axis.
5. A portable grinder according to claim 1, wherein the stop
(18-21), at least on the side facing the workpiece (7), is rounded
in a cross-sectional plane perpendicular to the pivot axis.
6. A portable grinder according to claim 1, wherein the stop
(18-21) comprises a roller (19, 20), which can be set against the
workpiece (7).
7. A portable grinder according to claim 6, wherein several rollers
(19, 20), arranged a certain distance apart, are provided.
8. A portable grinder according to claim 7, wherein the distance
between the rollers (19, 20) is adjustable.
9. A portable grinder according to claim 7, wherein the rollers
(19, 20) can be locked in place on a shaft (18) or rotate on an
axle.
10. A portable grinder according to claim 7, wherein two rollers
(19, 20) comprise slanted rolling surfaces (24, 25) on their facing
sides, by which the guide stop makes contact with two different
workpiece surfaces coming together at an angle.
11. A portable grinder according to claim 1, wherein the pivot axis
formed by the stop (18-21) extends in the tangential direction
relative to a rotational axis of the grinding head (5).
12. A portable grinder according to claim 1, wherein the pivot axis
formed by the stop (18-21) is parallel to the surface ground by the
grinding head (5).
13. A portable grinder according to claim 11, wherein the stop
(18-21) can be pivoted toward the rotational axis of the grinding
head (5) and locked in place in a desired pivot position.
14. A portable grinder according to claim 1, wherein the machine
comprises an elongated housing (1) enclosing the drive motor for
the grinding head (5), where a drive shaft (4) for the grinding
head (5) projects, preferably at an angle, from the housing
(1).
15. A portable grinder according to claim 14, wherein the stop is a
component of a unit (9) which comprises the grinding head (5) and
which can be connected to the housing (1).
16. A portable grinder according to claim 1, wherein the lengthwise
dimension of the handle (3) near the grinding head is preferably
parallel to the pivot axis.
17. A portable grinder according to claim 1, wherein the grinding
head comprises a multi-layer grinding disk, preferably with a steel
backing plate.
18. A portable grinder according to claim 15, wherein the unit (9)
comprises a bushing part (28), in which the grinding head (5) is
rotatably supported.
Description
[0001] The present invention pertains to a portable grinder with a
grinding head, the grinding contact zone of which can be placed
against a workpiece.
[0002] Portable grinders of this type which can be placed against a
workpiece so that the machine resists tipping in at least one
direction are known from WO 2005/095052 A1. What is described here
is, among other things, a grinder with a conical grinding head for
grinding down edges. The machine has a ring-shaped plate
concentrically surrounding the grinding head by which the grinder
can be set against a workpiece surface adjacent to the edge. This
portable grinder makes it possible to remove large amounts of the
material quickly. The degrees of freedom for the movement of the
grinding head, however, are limited. Angle grinders with grinding
heads which can be moved into any desired position are also
known.
[0003] The invention is based on the goal of creating a novel
portable grinder which combines greater flexibility with respect to
the movement of the grinding head with high removal capacity and
grinding quality.
[0004] The inventive portable grinder which achieves these goals is
characterized by a stop, which is located a certain distance away
from the grinding contact zone. When the grinder is placed against
the workpiece, the stop forms a pivot axis for the grinding head
and the fulcrum of a lever around which at least one handle can be
rotated
[0005] It is advantageous that the angular position of the grinding
head relative to the direction toward the pivot axis is largely
determined by the stop, which is located a certain distance away
from the grinding contact zone. Changes to this angular position
are possible only in association with the approach of the grinding
head to the surface of the workpiece in the direction more-or-less
perpendicular to that surface. The user of the grinder can
therefore, without the tilting of the grinding head in the
direction just mentioned, i.e., with a high degree of grinding
accuracy, exert a large amount of grinding contact force and a
large amount of force in the forward-feed direction parallel to the
workpiece surface.
[0006] In the preferred embodiment, two handles, arranged a certain
distance apart, are provided, so that the machine can be held and
guided with both hands, wherein, in a projection onto the
workpiece, the grinding head and/or the stop is located between the
handles.
[0007] The stop is preferably designed so that the machine can be
pressed against the workpiece without the danger of tilting in the
direction of the pivot axis. Thus, the user can focus to an even
greater degree on the exertion of suitable grinding contact and
forward-feed forces.
[0008] The stop is preferably rounded in a cross-sectional plane
perpendicular to the pivot axis. It can be formed, for example, by
a pin with a circular cross section.
[0009] In an especially preferred embodiment of the invention, the
stop comprises a roller, which can be set on the workpiece, wherein
several rollers arranged a certain distance apart can be provided.
The distance between the rollers is preferably adjustable.
[0010] The rollers can be locked in place on a shaft or can rotate
on an axle. Preferably the rollers can be locked in place on the
shaft at the desired distance from each other.
[0011] In another embodiment of the invention, two rollers are
provided, and the sides of these roller which face each other
comprise slanted rolling surfaces, by which the guide stop makes
contact with two different workpiece surfaces, which come together
at an angle. A guide stop of this type with rolling surfaces
beveled at a 45.degree. angle can, for example, be set against two
surfaces of a workpiece which come together at a right angle in
order to grind a 45.degree. bevel on the edge formed by the meeting
surfaces.
[0012] The rolling surfaces can be beveled to different angles. For
example, one can have a 30.degree. angle, the other a 60.degree.
angle, so that a 30.degree. bevel is produced.
[0013] Whereas a belt grinder head, for example, can be used as the
grinding head, a rotating grinding head is used in the preferred
embodiment of the invention, wherein the pivot axis formed by the
guide stop extends in a tangential direction relative to the
rotational axis of the grinding head.
[0014] The pivot axis formed by the guide stop is also preferably
parallel to the surface ground by the grinding head.
[0015] The guide stop can preferably be pivoted toward the
rotational axis of the grinding head and locked in place in a
desired position. The position can be adjusted in correspondence
with the inclination of the slanted ring-shaped grinding surfaces
attached to the end surface of the grinding disk.
[0016] In the preferred embodiment of the invention, the machine
has an elongated housing, which encloses a drive motor for the
grinding head, wherein a drive shaft for the grinding head
projects, preferably at an angle, from the housing.
[0017] A handle can be provided a certain distance away from the
pivot axis, especially at each of the two longitudinal ends of the
housing, as a result of which the length of the lever extending to
the pivot axis becomes quite long. This makes it possible in turn
to exert a large amount of pressure on the workpiece and thus also
to exert high grinding forces. It is advisable here for the
lengthwise dimension of the handle near the grinding head to be
parallel to the pivot axis.
[0018] In an especially preferred embodiment, the guide device is a
component of a unit which comprises the grinding head and which can
be connected to the housing. Thus, for example, the housing of a
standard commercial angle grinder can be used, and the angle
grinder can be converted into the inventive device.
[0019] In one embodiment of the invention, the grinding head
comprises a multi-layer grinding disk, especially with a wire
backing plate, so that high contact forces can be absorbed. It is
advisable to provide a hexagonal socket, for example, to prevent
normal grinding heads from being used in such grinders.
[0020] The invention is explained in greater detail below on the
basis of exemplary embodiments and the attached drawings, which
illustrate these embodiments:
[0021] FIG. 1 shows a perspective view of a first exemplary
embodiment of an inventive portable grinder,
[0022] FIG. 2 shows the portable grinder of FIG. 1 in a perspective
view rotated 90.degree. from that of FIG. 1,
[0023] FIG. 3 shows a detail of the portable grinder of FIG. 1,
[0024] FIG. 4 shows an exploded perspective view of the portable
grinder of FIG. 1, which comprises a unit which can be connected to
a standard commercial angle grinder,
[0025] FIG. 5 shows a cross-sectional side view of the unit of FIG.
4 in isolation,
[0026] FIG. 6 shows a partial perspective view of the unit of FIG.
4, and
[0027] FIGS. 7-9 show various perspective views of another
exemplary embodiment of an inventive portable grinder.
[0028] A portable grinder comprises an elongated housing 1 with a
handle 2 at one end and another handle 3, designed as a U-shaped
bracket, at the opposite end.
[0029] A drive shaft 4 (FIG. 4) projects from the side of the
housing 1. This shaft is in drive connection with a motor/gear
assembly (not shown) installed in the housing 1.
[0030] The drive shaft 4 drives a grinding head 5 with a grinding
disk 6. The grinding disk 6 comprises, on the side facing the
workpiece 7, a ring-shaped surface 8 (FIG. 3), which is at a
certain angle to the grinding plane and which is in grinding
contact with the workpiece 7.
[0031] The grinding head 5 is a component of an assembly 9, shown
separately in FIG. 4, which comprises a cylindrical connecting
piece 10, which can be clamped to a shoulder 11 on the housing 1.
When this clamping connection is established, the drive shaft 4 is
brought into drive connection with the grinding head 5.
[0032] The cylindrical connecting piece 10 of the assembly 9 is
attached to a U-shaped retaining part 12 with side pieces 13 and
14, which thus form the sides of the U. A U-shaped sheet metal part
15 is hinged to these side pieces by screwed connections. A certain
distance away from each of these screwed connections, another
screwed connection is provided, wherein the screw of each these
connections passes through a slot 16 in the associated side piece
of the U-shaped sheet-metal part 15. A spark shield 22 is screwed
to one side of the U-shaped sheet-metal part 15.
[0033] Between the side pieces of the sheet-metal part 15, the base
side of which preferably comprises a Plexiglas-covered opening 17,
there extends a shaft 18, which is rotatably supported in shaft
bearings 21 on the side pieces and on which two rollers 19, 20 are
seated, which can be connected nonrotatably to the shaft by
clamping screws. Instead of the shaft, it would also be possible to
provide an axle pin, connected rigidly to the U-shaped sheet-metal
part 15, on which the rollers are free to rotate independently of
each other.
[0034] As can be seen in FIGS. 5 and 6, a rotating part 26 of the
grinding head 5, which can be connected to the grinding disk 6, is
supported rotatably by a ball bearing 27 in a bushing part 28. The
bushing part 28 is connected to the connecting piece 10. The drive
shaft 4 engages in a bore 29 in the rotating part 26, wherein a
clutch 30 establishes the drive connection with the rotating part
26.
[0035] So that the flat surface of the workpiece 7 can be ground,
e.g., so that the projecting part of a weld 23 can be ground off
(FIG. 2), the grinding contact zone 26 of the grinder is pressed
with the help of the two handles 2 and 3 against the workpiece 7
and with the help of the rollers 19, 20, wherein, in particular, by
suitably distributing the load, the user can generate the desired
grinding pressure perpendicular to the workpiece surface and also
the desired forward-feed in the longitudinal direction of the weld
23. The rotational axis of the shaft 18 forms a fulcrum for the
rotation of the handles and a pivot axis 27 for the grinding head
5. The distance of the axis from the handle 2 is approximately 300
mm, the distance to the handle 3 about 150 mm. During the process
of feeding the grinder forward along the weld 23, the rollers or
wheels 19 and 20 roll over the workpieces surface. Because of the
distance between the rollers, which is adjustable, the grinder is
unable to tilt in the direction of the rotational axis of the shaft
18, that is, perpendicular to the forward-feed direction. The
grinder sits on the surface of the workpiece 7 with 3-point
support. The guidance by the shaft 18 with the rollers 19 and 20
makes it possible for the user of the grinder to focus fully on the
exertion of the correct pressing and forward-feed forces. The
rollers 19 and 20 mounted nonrotatably on the shaft 18,
furthermore, make it much easier to guide the grinder straight
along the weld 23.
[0036] Instead of the rollers, between which the weld is located,
it would also be possible to use a shaft with a suitable profile.
In the case of the exemplary embodiment according to FIGS. 5-7, the
same or equivalent parts are designated by the same reference
numbers as those used for the preceding exemplary embodiment, where
the letter "a" is attached to the reference number in question.
[0037] The exemplary embodiment according to FIGS. 5-7 differs from
the preceding exemplary embodiment in that rollers 19a and 20a,
seated nonrotatably on a shaft 18a, comprise ring-shaped surfaces
24, 25, oriented at an angle of 45.degree. to the axis of the
shaft, on their facing sides.
[0038] The portable grinder according to FIGS. 5-7 can therefore be
set against the surfaces of a workpiece 7a which come together at a
right angle and thus be used as a bevel grinder. The machine cannot
tip in the direction perpendicular to the longitudinal direction of
the bevel. The grinding of flat bevels is thus facilitated even
more.
[0039] The assembly 9 or 9a of the previously described bevel
grinder can be locked in place in the desired position relative to
the rotational axis of the grinding head 5, wherein this position
depends on the angle of inclination of the ring-shaped surface 8 on
the grinding disk 7. The setting is accomplished in such a way that
the surface line of the ring-shaped surface 8 is parallel to the
workpiece surface in the forward-feed direction.
[0040] In certain applications, it can be advantageous for only an
axle or shaft to rest directly on an edge. The shaft can be
profiled, so that it cannot slide off laterally. In such
applications the rollers can be pushed all the way to the ends of
the shaft and locked in place there.
* * * * *