Note: Descriptions are shown in the official language in which they were submitted.
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1 "VARIABLE ANGLE CORNER TOOL"
2
3 FIELD OF THE INVENTION
4 The invention relates to adjustable corner tools and in particular to
variable angle corner tools for use in finishing corners with spreadable
material
6 such as drywall compound.
7
8 BACKGROUND OF THE INVENTION
9 Drywall corner tools are commonly used to finish wall corners
provided by adjacent intersecting walls. Many conventional drywall corner
11 finishing tools in the marketplace are limited to applications against
typical 90
12 degree angular inside corner wall joints. In recent years, the use of other
angular
13 measurements have been incorporated in building construction, resulting in
larger
14 and smaller angles than 90 degrees, such as vaulted ceilings or corner bay
window coves.
16 Angles other than 90 degrees can be finished by hand using a joint
17 knife or variable angle hand trowel. This method is very time consuming
since
18 each side of the angle must be finished separately and allowed to dry. To
assist
19 in this finishing process, a product called "corner bead" was made
available in a
variety of popular angles, which is placed into the corner to fill the joint
gap and
21 provide a straight vertical corner line before drywall compound (mastic or
mud) is
22 applied and finished by hand. Such corner bead strips, however, increase
the
23 cost of drywalling.
24 To alleviate problems associated with variable wall corner angles,
drywall corner tools have been developed having adjustable corner angles. For
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1 example, such tools have been disclosed in U.S. Patent Nos.: 5,442,832,
issued
2 on August 22, 1995; 5,467,497, issued on November 21, 1995; 5,544,384 issued
3 on August 13, 1996; and Patent No. 5,774,924, issued on July 7, 1998. Each
of
4 these patents disclose corner tools having hinged blades for pivotal
movement of
the blades about the hinge axis to form a variety of corner angles. Slideably
or
6 pivotally connected arms extend between the blades to support the blades and
7 adjust the blades to a desired corner angle. Typically, the angle is fixed
by a
8 locking member that prevents sliding or rotation of the arms about the
handle
9 prior to use. Alternatively, the '497 patent discloses a locking pin bolt
extending
through the hinge for fixing the blades at a desired angle.
11 In some cases, a particular wall corner angle is variable, either by
12 design or because the corner is not true, such that fixedly variable angle
corner
13 tools may not adequately finish such a corner. Although it is possible to
not fix
14 the angle of the prior art corner tools to allow the blades to move
together for
adjusting to decreasing wall corner angles during use, the blades will not
16 automatically return to their original position or adjust to increasing
wall angles.
17 There is, therefore, a need for an improved adjustable corner tool.
2
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1 SUMMARY OF THE INVENTION
2 An improved adjustable corner tool for finishing wall corners with
3 spreadable material is provided that allows the angle defined by the blades
of the
4 corner tool to dynamically adjust to variations in wall corner angles during
use.
The corner tool can be used for finishing wall corners in the range of about
160
6 degrees to 40 degrees and can also be fixed at a specific angle is so
desired,
7 therefore is useful for a wide variety of applications.
8 In one embodiment invention, the adjustable corner tool comprises
9 a pair of hinged blades that are outwardly biased to urge the blades apart
and
whereby force applied against the blades moves the blades together. To
11 outwardly bias the blades, an angle control assembly is connected between
the
12 back surfaces. Generally, the angle control assembly includes a central
13 mounting block, fixed-length arms pivotally connected to each of the blades
and
14 the central mounting block, and springs that rotate the arms away from each
other to thereby outwardly bias the blades. Preferably, pairs of spaced upper
and
16 lower arms are used to optimize the transfer of force between the angle
control
17 assembly and the length of the blades. Furthermore, while only one spring
is
18 required to outwardly bias the blades, preferably at least twa springs are
used,
19 with each spring acting on an arm connected to one or the other blades. The
invention may also be adapted to suit a variety of purposes. For example, the
21 arms can be clamped to resist or prevent rotation and thereby substantially
fix the
22 angle of the corner tool. Stops that prevent rotation of the arms can also
be used
23 to define a maximum angle of the corner tool.
24 In a broad aspect of the invention, there is provided an adjustable
corner tool comprising: first and second blades, each blade having a mating
3
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1 edge, a front surface and a back surface, the blades hingedly connected at
the
2 mating edges, the back surfaces defining an angle; and an angle control
3 assembly connected between the back surfaces, the angle control assembly
4 outwardly biasing the blades to urge the blades apart to increase the angle
and
wherein pressure applied against the front surfaces moves the blades together
to
6 thereby decrease the angle.
7 In another broad aspect of the invention, there is provided an angle
8 control assembly for a corner tool having first and second blades, each
blade
9 having a mating edge, a front surface and a back surface, the blades
hingedly
connected at the mating edges, the back surfaces defining an angle, the angle
11 control assembly comprising: first and second mounting plates; and a
mounting
12 block pivotally connected between first and second mounting plates, the
angle
13 control assembly outwardly biasing the first and second mounting plates for
14 moving the plates apart, wherein attachment of the first mounting plate to
the first
blade and attachment of the second mounting plate to the second blade
16 outwardly biases the blades to urge the blades apart to increase the angle
and
17 wherein pressure applied against the front surfaces moves the blades
together to
18 thereby decrease the angle.
19 The adjustable corner tool may be used with any spreadable
material, such as drywall compound, plaster, and grout. Although the
adjustable
21 corner tool is intended for use in finishing wall corners, it can be used
in any
22 application in which finishing of such spreadable material in a corner is
required.
23 The adjustable corner tool may also be modified to also function as an
injection
24 head for applying spreadable material to a corner.
4
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1 BRIEF DESCRIPTION OF THE DRAWINGS
2 In drawings which are intended to illustrate embodiments of the
3 invention and which are not intended to limit the scope of the invention:
4 Figure 1A is a back perspective view of one embodiment of an
adjustable corner tool of the present invention;
6 Figure 1 B is a back perspective view of the angle control assembly
7 of Fig. 1A shown in isolation from the blades;
8 Figure 2 is a front perspective view of the adjustable comer tool
9 according to Fig. 1;
Figures 3A-C are top plan views of another embodiment of a corner
11 tool of the present invention, with the blades actuated to 160 degrees
(with the
12 stops removed in Fig. 3A), 95 degrees and 40 degrees, respectively;
13 Figure. 4 is a back view of the adjustable corner tool of the present
14 invention according to Fig. 3B
Figures 5A and 5B are top plan and bottom plan views,
16 respectively, of the adjustable corner tool according to Fig. 1;
17 Figure 6 is an exploded view of the adjustable corner tool according
18 to Fig. 1;
19 Figure 7 is a perspective view of a blade of the adjustable corner
tool of the present invention;
21 Figure 8 is a top plan view of an embodiment of a portion of the
22 hinge connection of an adjustable corner tool of the present invention
having a
23 beveled mating edge; and
5
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Figure 9A is a bottom plan view and Figure 9B is a back view of
2 another embodiment of an adjustable corner tool of the present invention
having
3 an injection head modification.
6
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1 DESCRIPTION OF THE PREFERRED EMBODIMENT
2 Referring to Figs. 1 A-3C, a variable angle corner tool 100 is shown
3 having generally planar outwardly biased first and second blades 10a, 10b
4 connected at mating edges 12 by a hinge 14 and an angle control assembly 16
positioned between the back surtaces 18a, 18b of the blades 10a, 10b. Herein,
6 the surface of the blades 10a, 10b which engage the wall are deemed to be
the
7 front surface 26a, 26b and the opposing surface accessed by an operator is a
8 back surface 18a, 18b. The angle control assembly 16 maintains a general V
9 arrangement of the blades 10a, 10b and allows the angle A defined by the
back
surfaces 18a, 18b to be dynamically adjusted from about 160 degrees to 40
11 degrees, as particularly seen in Figs. 3A-C. The angle control assembly 16
12 includes a mounting block 20 positioned between the back surfaces 18a, 18b,
13 pivotal connections 22 between each of the mounting block 20 and the first
and
14 second blades 10a, 10b, and outwardly biasing means 24. The pivotal
connections 22 allow the blades 10a, 10b to move apart or together upon
16 application of appropriate force to the blades 10a, 10b, typically
initiated through
17 the mounting block 20. In particular, outwardly biasing force provided by
the
18 outwardly biasing means 24 urges the blades 10a, 10b apart to thereby
increase
19 the angle A, while reactive force applied against the front surfaces 26a,
26b acts
against the outwardly biasing force to move the blades 10a, 10b together to
21 thereby decrease the angle A.
22 The mounting block 20 also provides a point of attachment for a
23 handle (not shown), such as a pole, to assist the user in the operation of
the
24 corner tool 100. As shown, the mounting block 20 provides a socket 28
between
7
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1 upper and lower ends 30, 32 for accommodating a pole with a conventional
ball
2 joint and as secured by a retaining spring clip 34.
3 With further reference to Figs. 4-6 the pivotal connections 22 of the
4 angle control assembly 16 are provided by pivotally connected arms 36a, 36b,
38a, 38b extending at a fixed length between the mounting block 20 and the
6 blades 10a, 10b. More particularly, each of a spaced apart first upper arm
36a
7 and first lower arm 38a is pivotally connected at a distal end 40 to the
first blade
8 10a, while each of a spaced apart second upper arm 36b and second lower arm
9 38b is pivotally connected at a distal end 40 to the second blade 10b, with
the
upper arms 36a, 36b and lower arms 38a, 38b each pivotally connected at a
11 proximal end 44 to upper and lower ends of the mounting block 30, 32. For
12 connection of the arms 36a, 36b, 38a, 38b to the blades 10a, 10b, first and
13 second mounting plates 48a, 48b are attached to the first and second blades
14 10a, 10b. A pair of upper and lower posts 50, 52 extend perpendicularly
from
each of the mounting plates 48a, 48b to which the upper arms 36a, 36b and
16 lower arms 38a, 38b are respectively attached.
17 The mounting plates 48a, 48b are attached to the blades 10a, 10b
18 by any suitable means, such as bolts 49 or welding. While the mounting
plates
19 48a, 48b may be of any suitable shape (Figs. 1A and 4), mounting plates
48a,
48b that substantially cover the back surfaces 18a, 18b, as particularly seen
in
21 Fig. 4, are preferred for providing structural support to the blades 10a,
10b.
22 Pivotal connection of the arms 36a, 36b, 38a, 38b is achieved by
23 passing a suitable pivot fastener 54, such as a rivet, pin or bolt, through
aligned
24 pivot holes 56 formed in the arms 36a, 36b, 38a, 38b, mounting plates 48a,
48b,
and mounting block 20, as required. Preferably, each pair of upper arms 36a,
8
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1 36b and lower arms 38a, 38b are pivotally connected to the mounting block 20
by
2 a single pivot fastener 54, thereby providing a common pivot point for each
pair of
3 upper arms 36a, 36b and lower arms 38a, 38b. The pivot fasteners 54 can be
4 adjustable to clamp the arms 36a, 36b, 38a, 38b to provide variable
resistance to
pivotal movement of the arms 36a, 36b, 38a, 38b or to lock the arms 36a, 36b,
6 38a, 38b in place at a specific angle, as desired. For example, as shown,
the
7 pivot fastener 54 is a threaded bolt whereby the fastened arm is retained
8 between the head of the bolt 58 and a nut 60 threaded onto the shaft 62. To
9 clamp the arms 36a, 36b, 38a, 38b, the nut 60 is simply threaded further
onto the
shaft 62, while loosening of the nut 60 will unclamp the arm 36a, 36b, 38a,
38b.
11 Alternatively, upper and lower fasteners may interconnect to form such a
nut-and-
12 bolt arrangement, as seen in Fig. 4.
13 In general, the outwardly biasing means 24 acts between any of the
14 arms 36a, 36b, 38a, 38b and the mounting block 20 to rotate the respective
arm
36a, 36b, 38a, 38b about the pivot fastener 54, while the arms 36a, 36b, 38a,
38b
16 act between the mounting block 20 and the blades 10a, 10b to move the
blades
17 10a, 10b outwardly and away from each other. In particular, the outwardly
18 biasing means 24 includes upper and lower springs 64, 66 attached to the
first
19 upper arm 36a and the second lower arm 38b, respectively. To pre-load the
springs 64, 66, a distal end of each spring 66 is secured to its respective
arm
21 36a, 38b, a proximal end of each spring 69 is secured to the mounting block
20,
22 and the coils of the springs 64, 66 are positioned about a biasing post 70.
23 Conveniently, the biasing posts 70 correspond to the pivot fasteners 54
24 positioned on the mounting block 20, with a bushing 71 and washer 72 also
positioned around the fastener 54. The springs rotationally bias the arms 36a,
9
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1 38b to rotate the arms 36a, 38b away from each other so that the mounting
block
2 20 moves toward the back surfaces 18a, 18b (see Figs. 3A-3C) causing the
arms
3 36a, 38b to push against the blades 10a, 10b and urge the blades 10a, 10b
4 apart. In other words, the upper spring 64 acts on the first upper arm 36a
to
outwardly bias the first blade 10a, while the lower spring 66 acts on the
second
6 lower arm 38b to outwardly bias the second blade 10b. Alternatively, the
upper
7 and lower springs 64, 66 may be inversely attached to the upper second arm
36b
8 and lower first arm 38a without affecting the overall operation of the
corner tool
9 100.
Any suitable means for securing the distal and proximal ends of the
11 springs 68, 69 may be used. As shown, the distal end of the springs 68 are
12 hooks that are inserted into spring holes 74 formed in the arms 36a, 38b,
while U-
13 shaped proximal ends 68, 69 are positioned about spring retainer pins 76
14 attached to the upper and lower ends of the mounting blocks 30, 32 and
adjacent
to the respective biasing posts 70. To prevent the spring retainer pins 76
from
16 interfering with the pivotal movement of the arms 36a, 36b, 38a, 38b, cut-
outs 78
17 are provided in the arms 36a, 36b, 38a, 38b, as required.
18 In use for finishing a wall corner, the outwardly biased blades 10a,
19 10b of the corner tool 100 form a first angle that is larger than the
maximum
angle of the wail corner. The corner tool 100 is then placed in the wall
corner,
21 generally having drywall compound or other spreadable material applied
thereto,
22 with the front surfaces 26a, 26b engaging the walls. Moderate pressure is
23 applied upon the mounting block 20 towards the blades 10a, 10b to push the
24 corner tool 100 into the wall corner and, consequently, resistive forces
applied to
the blades 10a, 10b compress the springs 64, 66 and cause the blades 10a, 10b
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1 to move together to form a second angle corresponding to the angle of the
wall
2 corner. As the corner tool 100 is stroked along the length of the wall
corner with
3 continual application of pressure to spread the compound, the angle A of the
4 blades 10a, 10b will adjust to substantially always match the angle of the
wall
corner. In particular, the combination of the outward biasing and the pivotal
6 connection of the blades 10a, 10b allow the angle A to dynamically increase
or
7 decrease according to variations in the wall corner angle, such as if the
corner is
8 not true.
9 Preferably, the first angle of the blades 10a, 10b is slightly larger
than the maximum angle of the wall corner. For example, for a right angle wall
11 corner, the first angle may be 95 degrees. To restrain the blades 10a, 10b
to a
12 maximum angle, stops 80, such as bolts, are positioned on the mounting
block 20
13 adjacent to an outer edge 82 of each of the arms 36a, 36b, 38a, 38b to
restrict
14 rotational biasing of the arms 36a, 38b, 38a, 38b. If the desired first
angle is
larger that maximally permitted by the stops 80, the stops 80 may be removed
as
16 necessary, as seen in Fig. 3A. In addition, the placement of stops 80
beside
17 pairs of first and second arms 36a, 36b, 38a, 38b also act to help keep the
18 mounting block 20 centered to the blades 10a, 10b, particularly if the user
is
19 standing off center of the comer tool 100 when pressure is being applied.
While the invention has thus far been described with respect to the
21 preferred embodiment, other embodiments are also contemplated. For example,
22 outwardly biasing means 24 may be attached to all of the arms or to only
one arm
23 36a, 36b, 38a, 38b. Alternatively, only one pair of first and second arms
36a, 36b
24 or 38a, 38b can be used with outwardly biasing means 24 attached to one or
both
arms 36a, 36b, 38a, 38b. Notably, the use of outwardly biasing means 24 for
11
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1 biasing both the first and second blades 10a, 10b allows force to be applied
2 equally through to both blades 10a, 10b if uneven force is applied, such as
if the
3 user is standing off-centre of the corner tool 100. In addition, the
arrangement of
4 the spaced apart upper and lower arms 36a, 36b and 38a, 38b provides
structural support along the length of the corner tool 100 as force is being
6 applied.
7 With reference to Figs. 6 and 7, the blades 10a, 10b may be of any
8 shape suitable for the construction and purpose of the corner tool 100. As
9 shown, the blades 10a, 10b are as found in a typical drywall flusher head,
with
each blade having a general wing shape with angled tips 84 and lower edges 86
11 and downwardly projecting sliders 88 extending from each of the front
surfaces
12 26a, 26b.
13 Any hinge connection that permits pivotal movement of the blades
14 can be used. For example, with reference to Figs. 7 and 8, the hinge 14 is
a
piano hinge formed from spaced apart hinge cylinders 90 projecting from and
16 extending along the mating edge 12 of each of the blades 10a, 10b. The
hinge
17 cylinders 90 are aligned for receiving a rod 92 therethrough, such that the
mating
18 edge 12 of each blade 10a, 10b is adjacent to the hinge cylinders 90 of the
other
19 blade 10a, 10b. In general, the hinge connection should be substantially
flush
with the front surfaces 26a, 26b to minimize impact on the surface of the
finished
21 corner. Furthermore, with particular reference to Fig. 8, the mating edge
12 may
22 be chamfered or beveled inwardly to allow for a substantially tight fitting
of the
23 mating edge 12 with the hinge member 90 and therefore allow for a smoother
24 finish. For example, for a hinge having an outer diameter of about 1/8",
the
mating edge is beveled at about 60 degrees.
12
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1 The corner tool 100 may be made of any material suitable for the
2 purpose for which it is intended, including metal, plastic, or a combination
thereof.
3 In addition, the corner tool 100 may be constructed in any manner which
4 achieves the ultimate function. For example, the posts 50, 52 may be
integrally
formed with the blades 10a, 10b such that mounting plates 48a, 48b per se are
6 not required.
7 Referring to Figs. 9A and 9B, the corner tool 100 can be modified to
8 also function as an injection head for applying spreadable material, such as
9 drywall compound, to a wall corner. In this case, the socket 28 in the
mounting
block 20 accommodates a compound conduit having a ball member (not shown)
11 and the socket 28 is adapted to include a cavity 98. Tubing 94 is connected
12 between openings (not visible) in the mounting block 20 and the blades 10a,
10b,
13 where the openings in the mounting block 20 are in communication with the
14 cavity 98. Preferably the mounting block 20 would have increased depth to
accommodate the cavity 98 and the openings therein.
16 In use, a pump delivers drywall compound through the compound
17 conduit to the socket 28 and the compound is injected into the cavity 98.
The
18 compound then flows through the tubing 94 to the front surfaces 26a, 26b of
the
19 blades 10a, 10b, where the compound can be spread along a wall corner with
the
corner tool 100, as described previously. If necessary, seals (not shown) are
21 used to prevent leakage of compound from the socket 28.
22 One or more tubing 94 can be used, as desired, and the tubing 94
23 can be made of any flexible material that permits movement of the blades
10a,
24 10b. For example, as shown, the tubing 94 is plastic and fittings 99, such
as
13
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1 brass fittings, are used to connect the tubing 94 to the mounting block 20
and the
2 blades 10a, 10b. The tubing 94 can also be made of metal having hinged
joints.
3 Although preferred embodiments of the invention have been
4 described in some detail herein above, those skilled in the art will
recognize that
various substitutions and modifications of the invention may be made without
6 departing from the scope of the invention as defined by the claims as
defined
7 herein.
14
