U.S. patent number RE30,519 [Application Number 06/094,591] was granted by the patent office on 1981-02-17 for accessory support plates for a magnet base drill.
Invention is credited to Everett D. Hougen.
United States Patent |
RE30,519 |
Hougen |
February 17, 1981 |
Accessory support plates for a magnet base drill
Abstract
A magnet base drill having a pair of plates formed of magnetic
material removably mounted on either the side walls or the bottom
face of the electromagnet forming the base of the drill and
adjustable thereon to contact portions of a convex support surface
spaced laterally outwardly from the central lonitudinal axis of the
electromagnet when the latter is positioned on the support
surface.
Inventors: |
Hougen; Everett D. (Flint,
MI) |
Family
ID: |
22246039 |
Appl.
No.: |
06/094,591 |
Filed: |
November 15, 1979 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
745393 |
Nov 26, 1976 |
04047827 |
Sep 13, 1977 |
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Current U.S.
Class: |
408/76 |
Current CPC
Class: |
B25H
1/0071 (20130101); Y10T 408/554 (20150115) |
Current International
Class: |
B25H
1/00 (20060101); B23B 039/00 () |
Field of
Search: |
;408/72,76,103,105,108,241,712 ;409/175 ;90/DIG.23 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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896945 |
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May 1944 |
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FR |
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1260818 |
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Apr 1961 |
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FR |
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50-39479 |
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Nov 1975 |
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JP |
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Primary Examiner: Hinson; Harrison L.
Attorney, Agent or Firm: Barnes, Kisselle, Raisch &
Choate
Claims
I claim: .[.1. In combination, a portable drill unit having an
electromagnetic base for magnetically adhering the drill to a
magnetic support, said base having a bottom wall and a pair of
opposite side walls, a pair of plates formed of magnetic material,
means for mounting said plates on the side walls of said base for
vertical adjustment thereon, said plates having lower edge portions
and being adjustable on said base so that said lower edge portions
project downwardly below said bottom wall of said base, and means
for rendering at least the central portion of said bottom wall and
said plates magnetic when the electromagnet is energized, whereby,
when said base is mounted on a convex magnetic support surface,
said plates can be extended downwardly to a position wherein the
lower edge portions thereof engage portions of said support surface
at locations spaced laterally outwardly on opposite sides from the
central portion of said base to thereby magnetically adhere the
drill on said support in a stable position when the electromagnet
is energized..]. .[.2. The combination set forth in claim 1
including means for mounting said plates on said bottom wall for
lateral adjustment towards and away from each other in a plane
parallel to said bottom wall..]. .[.3. The combination set forth in
claim 1 wherein said plates are generally L-shaped..]. .[.4. The
combination set forth in claim 1 wherein said plates have a length
generally corresponding to the length of said base..]. .[.5. The
combination set forth in claim 4 wherein the plates have a width
equal to at least one-half the width of said base..]. .[.6. The
combination set forth in claim 5 wherein each plate has a pair of
parallel slots therein extending substantially the full width
thereof..]. .[.7. The combination set forth in claim 1 wherein the
means for adjustably mounting said plates on said base comprise a
pair of vertically elongated slots on each plate and a screw
extending through each slot and threaded into said base..]. .[.8.
The combination set forth in claim 1 wherein the side walls of said
base are formed of a magnetic material and form part of the
magnetic circuit of said electromagnet..]. .[.9. The combination
set forth in claim 8 wherein said plates contact the side walls of
said base to form part of said magnetic circuit..]. .[.10. The
combination set forth in claim 1 wherein each plate in vertical
section comprises a vertical leg having a short foot at one end
thereof angularly inclined to said vertical leg..]. .[.11. The
combination set forth in claim 9 wherein said foot is disposed
perpendicular to said vertical leg..]. .[.12. The combination set
forth in claim 8 wherein said foot is inclined to said vertical leg
at an acute
angle..]. .Iadd.13. In combination, a portable drill unit having an
electromagnetic base for adherring the drill to a magnetic support,
said base having a rectangular bottom wall and a pair of opposite
side walls, a pair of plates formed of magnetic material and
adapted to be mounted on said base for magnetically adherring the
drill unit to a cylindrical support surface having a diameter less
than the width of said base, each plate having a long planar leg
and a short transversely inclined foot extending lengthwise along
one edge thereof, means for mounting the plates one on each side
wall of said base, said plates being adapted to be mounted on the
side walls for vertical adjustment thereon with the feet extending
along lower edges thereof and projecting inwardly toward each other
in a plane below said bottom wall, and means for rendering said
bottom wall and said plates magnetic when the electromagnet is
energized, whereby, when said base is mounted on said support
surface with the longitudinal central portion of said bottom wall
abutting said surface, said plates can be adjusted vertically on
the side walls of the base to a position wherein the opposed inner
edge portions of said feet abut portions of said cylindrical
support surface at locations spaced laterally outwardly on opposite
sides from the central portion of said base, to thereby
magnetically adhere the drill unit on said cylindrical support
surface in a stable position when the electromagnet is energized.
.Iaddend. .Iadd.14. The combination as called for in claim 13
including means for mounting said plates on said bottom wall in
laterally opposed relation with the short feet projecting
downwardly along the inner opposed edges of the long legs and being
laterally adjustable toward and away from each other in a
horizontal plane parallel to said bottom wall to a position where
said short feet abut the convex surface of a cylindrical workpiece
having a diameter less than the width of the base when the central
portion of the bottom wall engages said convex workpiece surface.
.Iaddend. .Iadd.15. The combination as called for in claim 13
wherein said plates are generally L-shaped in cross section.
.Iaddend. .Iadd.16. The combination as called for in claim 13
wherein the long leg of each plate has a width equal to at least
one-half the width of said base. .Iaddend.
Description
This invention relates to a magnet base drill and, more
specifically, to accessory means for such drills to enable the firm
attachment thereof to convexly shaped support surfaces.
Drills having a base in the form of an electromagnet for supporting
the magnet on a magnetic support surface have been used for many
years. When the magnetic support surface is flat, such as the face
or web of a structural beam, little difficulty is encountered in
retaining the magnet in a fixed, stable position on the support.
However, such drills have not been used with any degree of success
on magnetic surfaces which are convex in shape, such as pipes and
cylindrical tanks. On a convex surface it is difficult to retain
the magnet in a stable position because of the inability to obtain
sufficient area of contact between the electromagnet and the convex
support surface and also because of the fact that the support
surface is in itself curved while the bottom face of the
electromagnet is flat.
The object of the present invention is to provide an accessory for
such magnet base drills which enables the drills to be easily and
firmly supported on a convex surface, such as an iron pipe.
More specifically, the present invention contemplates a pair of
plates formed of a magnetic material which are adapted to be
mounted on either the side walls or the bottom wall of the
electromagnet and so adjusted as to contact portions of the convex
surface spaced laterally outwardly from the central portion thereof
and thus provide sufficient additional contact surfaces for
enabling the drill to be firmly supported magnetically on the
support.
Other objects, features and advantages of the present invention
will become apparent from the following description and
accompanying drawings, in which:
FIG. 1 is a side elevational view of a magnet base drill having the
accessory plates of the present invention mounted on the bottom
face thereof;
FIG. 2 is a fragmentary end view of the drill shown in FIG. 1;
FIG. 3 is a bottom plan view of the drill along line 3--3 in FIG. 1
with the accessory plates removed;
FIG. 4 is a perspective view of one of the accessory plates
according to the present invention; and
FIGS. 5 through 9 show various arrangements of the accessory plates
on the base of the drill for accommodating the electromagnet to
workpieces of different sizes.
In FIG. 1 numeral 10 designates a magnet base drill substantially
identical with that shown in my U.S. Pat. No. 3,969,036, dated July
13, 1976. The base of the drill comprises an electromagnet 12 of
rectangular shape which is adapted to be energized and de-energized
by a switch S. Electromagnet 12 comprises a housing 14 formed as a
ferrous casting having front and rear end walls 15, flat side walls
16, a top wall 17 and an open bottom. Within the housing 14 there
is arranged an iron core 18 around which is wound a coil (not
illustrated). Core 18 is connected to or formed integrally with top
wall 17 and is spaced out of contact with walls 15,16.
Electromagnet 12 has a substantially flat bottom wall 20 defined by
the lower edges of the housing and the lower end face of the core
18. The space therebetween is filled with an insulating material,
such as a resin. The two poles of the magnet are defined by the
walls of the housing and core 18. When the lower edges of side
walls 16 and the lower end face of core 18 are bridged by a body of
magnetic material and the electromagnet is energized, the body of
magnetic material forms a continuous magnetic flux path between the
housing 14 of the electromagnet and core 18. The electromagnet base
thus far described is of conventional construction.
In accordance with the present invention the bottom face of the
electromagnet is provided with four threaded openings 22 at the
four corners thereof and each of the two side walls 16 is also
provided with a pair of threaded openings 24 spaced upwardly from
the bottom wall 20 of the electromagnet. The threaded openings
22,24 are utilized for attaching to the electromagnet a pair of
accessory plates 28. Accessory plates 28 are formed of a ferrous
material, such as steel, and are preferably of L-shape, having a
long leg 30 terminating in a short foot 32 extending perpendicular
to leg 30. In addition, each plate 28 is provided with a pair of
elongated slots 34, the spacing of which corresponds to the spacing
between openings 22,24. Plates 28 have a length generally
corresponding to the length of housing 14 and are adapted to be
secured to the side walls 16 or the bottom wall 20 of the
electromagnet by means of screws 36.
If it is desired to support drill 10 on a pipe, for example, which
has a diameter substantially smaller than the width of the
electromagnet, plates 28 can be mounted on the bottom face of the
electromagnet in the manner illustrated in FIGS. 1 and 2. Screws 36
extend through slots 34 and into threaded opening 22. Before the
screws are tightened the electromagnet is centered longitudinally
on the pipe 38. Thereafter the two plates 28 are shifted inwardly
until the feet 32 thereof contact the outer surface of the pipe.
Screws 36 then are tightened. When switch S is thereafter actuated
to energize the electromagnet, plates 28 cooperate with the pipe to
form a continuous magnetic flux path between core 18 and the
housing 14. The drill thus firmly adheres to the pipe in a stable
upright position so that the rotating drill bit 39 can be driven
downwardly to cut a hole in the pipe at a location forwardly of
base 12.
If the pipe on which the drill is to be supported has a diameter
only slightly smaller than the width of housing 14, then plates 28
can be mounted on the side walls 16 of housing 14 in the manner
illustrated in FIG. 5. More specifically, in FIG. 5 plates 28 are
mounted on side walls 16 with feet 32 of the plates projecting
inwardly toward each other. The plates are adjusted vertically and
clamped in place by screws 36 so that the inner opposed ends 41 of
feet 32 contact the periphery of pipe 40 above the center thereof
when the bottom face 22 of housing 14 is resting on the upper
surface of the pipe.
FIGS. 6 and 7 show the drill mounted on convex surfaces of
progressively greater diameters. In the arrangements shown in these
figures the feet 32 of plates 28 project outwardly and the rounded
corner portions 42 of the plates contact the convex support
surface. In FIG. 6 the support comprises a large diameter pipe 44
and in FIG. 7 the support comprises an even larger diameter convex
surface 46. In each instance plates 28 are adjusted vertically on
the side walls of housing 14 so that, when the bottom face 20 of
the electromagnet is positioned on the top of the support, the
corner portions 42 of plates 28 engage the convex support surface
at portions thereof spaced laterally outwardly from the central
longitudinal axis of the electromagnet.
In the event the support surface has an unusually large diameter,
such as the side wall of a large cylindrical tank, the accessory
plates 28 can be arranged on the side walls 16 of housing 14 in the
manner illustrated in FIG. 8. In this arrangement plates 28 are
secured to the side walls of the housing with the feet 32 at the
upper ends thereof so that the lower straight ends 48 of the plates
engage the support surface 50. The broken line showing in FIG. 8
illustrates the fact that it is not necessary to remove the plates
28 from housing 14 when the drill is used on a flat support
surface. In this case it is merely necessary to loosen screws 36,
shift the plates vertically to the position indicated at 28' and
then tighten screws 36. In this position the lower straight edges
48 of plates 28 are disposed above the bottom face 20 of the
housing.
FIG. 9 shows a modified form of accessory plate. Accessory plate 52
is similar in all respects to accessory plate 28, except that the
foot portion 54 thereof is inclined to the vertical leg of the
plate at an acute angle rather that at a right angle. Under some
circumstances the location of foot 54 at an acute angle such as
shown in FIG. 9 will present a larger area of surface contact
between the accessory plate and the convex support surface 56.
It will be appreciated that where plates 28 are arranged on housing
14 so that they contact the convex support surface along lines
disposed above the center of curvature of the convex surface the
drill is vertically supported along three laterally spaced
locations. This tends to provide a very stable positioning of the
drill on the convex surface. As shown in FIG. 5, this type of
support is obtainable even when the diameter of the pipe is less
than the width of the electromagnet base. This form of support is
also obtainable when the pipe diameter is as small as shown in FIG.
2 by simply mounting plates 28 on the bottom face of the base so
that the straight edges 48 engage the surface of the pipe instead
of the feet 32. This is possible because slots 34 extend
substantially the full width of legs 30 and the width of each leg
30 is equal to at least half the width of housing 14.
* * * * *