Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
.
This invention relates to the field of metalcutting
tools and, more specifically, it relates to those metal-
cutting tools known as drills.
The prior art method of drilling holes has been by
the use of twist drills, twist drills with brazed
carbide tips or drills having indexable carbide inserts.
The use of drills having indexable carbide inserts is
often preferred because of their consistent quality and
overall cost effectiveness.
Notwithstanding the economical advantages of drills
having indexable carbide inserts, twist drills are still
used for holes under about one- half inch in diameter.
The principal reason for still using the small twist
drills is that it has generally been thought to be
impractical to manufacture a small drill having index-
able carbide inserts.
It woul~ be desirable to have a small drill that
uses indexable carbide inserts because such a tool can
drill a~ higher speeds, for longer periods of time and
for less cost than twist drills.
However, the obstacles to manufacturing a small
drill having indexable carbide inserts are twofold.
Since such drills have a minimum of two inserts, the
inserts would have to be made very small so as to both
fit on the drill shank. These inserts would be costly
to make as well as difficult to handle. The first
obstacle then is that a drill employing small indexable
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indexable carbide inserts simply would not be economical
to manufacture. The second obstacle is that the shank
would become too weak to withstand ~he anticipated cut-
ting loads if two inserts were placed on the same end of
the shank.
Applicant, however, has solved the problems of the
prior art by utilizing a single indexable carbide insert
that acts as if it were two inserts. So far as appli-
cant is aware, this is the first use of a single index-
able insert on a drill.
A single carbide tip has been used in a ball end
mill as shown in United States Patent No. 4,132,493.
It is thus an object of this invention to manufac-
ture a drill that uses indexable carbide inserts and
that can drill holes under about one-half inch in
diameter.
It is another object of this invention to econo~
cally manufacture a drill that uses indexable carbide
inserts and that can drill holes under about one-half
inch in diameter.
It is a still further object of this invention to
manufacture a small drill that uses indexable carbide
inserts and that can effectively replace twist drills.
BRIEF SUMMARY OF I'HE INVENTION
.
According to the invention, there is disclose~ a
drill with a shank having a central axis of rotation.
There is only one inser~ on one end of the shank. The
insert has two cutting edges. The first cutting edge
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has a negative radial rake sur~ace and the second cut-
ting edge has negative axial and positive radial rake
surfaces. The first and second cutting edges cooperate
to form a radiused hole when rotated about the central
axis.
In another embodiment of the invention, there may
be more than one insert on the end of the shank.
The central axis of rotation passes through the
axial rake face of the second cutting edge. The first
cutting edge may have zero axial rake or positive axial
rake.
Preferably, the insert is indexable.
In a preferred embodiment, the first cutting edge
is substantially perpendicular to the central axis of
rotation so that a hole with a substantially flat bottom
is formed.
Preferably, the insert is in the shape of a diamond
when viewed in plan and the smaller of the included
angles of the diamond is between 75 degrees and 85
degrees. It is also preferable for the insert to be in
the shape of a square when viewed in plan.
The shank has a reduced diameter portion. The
insert is held to the shank by fastening means passing
through a perforation in the insert and terminating in a
recess in the shank.
The second cutting edge axial rake face preferably
extends outwardly with respect to the insert so as to
break out of the insert.
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In another embodiment, the insert ha.s at least one
other cutting edge having negative axial and positive
radial rake surfaces. This at least one other cutting
edge cooperates with the first and second cutting edges
to form a radiused hole when rotated about the central
axis.
In a further embodiment, the second cutting edge
may be concave.
According to the invention, there is a drill dis-
closed with a shank having a central axis of rotation.Only one cutting insert is disposed on the end of the
shank and the insert has first and second cutting edges
and a clearance face. The first cutting edge extends
inwardly and parallel to a plane containing the axis of
rotation. The second cutting edge extends inwardly from
the first cutting edge and when viewed from the end
forms an included angle of greater than 90 degrees
therewith. The first and second cutting edges are
oriented along the forward portion in the rotational
sense of the clearance face. The clearance face inter-
sects the plane without intersecting the axis of rota-
tion. The first and second cutting edges cooperate so
as to rotatably cut a hole.
In another embodiment of the drill, there is at
least one cutting insert disposed on the end of the
shank.
The second cutting edge has a rake face and prefer-
ably the axis of rotation passes through the rake face.
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The first cutting edge has a negative radial rake
surface and the second cutting edge has negative a~ial
and positive radial rake surfaces. The first cutting
edge may have zero axial rake or positive axial rake.
The insert is most preferably indexable.
Preferably, the first cutting edge is substantially
perpendicular to the axis of rotation so that a hole
with a substantially flat bottom is formed.
The insert may be in the shape of a diamond when
viewed in plan with the smaller of the included angles
of the diamond being between 75 degrees and 85 degrees.
Alternatively, the insert may be in the shape of a
square when viewed in plan.
The shank has a reduced diameter portion and the
insert is disposed on the end of the reduced diameter
portion of the shank. The insert is held to the shank
by fastening means passing through a perforation in the
insert and terminating in a recess in the shank. The
drill may also have means for supplying coolant which
are internal to the shank and exit the shank at the end
of the reduced diameter portion.
The second cutting edge may comprise a plurality o~
cutting segments. The orientation of each of the seg-
ments differs in orientation from the previous cutting
segment so that when viewed from the end the included
angle between the first of said segments and the first
cutting edge and the included angle between each
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subse~uent cutting segment and the previous cutting seg-
ment is greater than 90 degrees.
In another embodiment, the second cutting edge is
substantially concave. l'he concave cutting edge and its
axial rake face form a groove which narrows in depth and
width away fro~ the concave cutting edge.
According to the invention, disclosed i9 a cutting
insert of hard wear resistant material. The insert has
top and bottom faces and a peripheral wall joining the
top and bottom faces. The insert body is polygonal when
viewed in plan. One of the top and bottom faces acts as
a seating face and the other acts as a cutting face.
There are first cutting edges formed on opposite sides
of the cutting face at the juncture of the cutting face
with the peripheral wall. One end of each of the first
cutting edges terminates in a juncture with a second
cutting edge that extends from said cutting face toward
said seating face. The first and second cutting edges
cooperate to form a radiused hole when rotated about a
central axis.
Each of the second cutting edges has a rake face
which extends upwardly awây from the seating face so
that it breaks out through the cutting face.
Preferably, the insert is indexable.
Preferably, the insert is in the shape of a diamond
when viewed in plan and the smaller of the included
angles o~ the diamond is between 75 degrees and ~5
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degrees. Preferably, also, the insert is in the shape
of a square when viewed in plan.
In other embodiments, each of the second cutting
edges joins with at least one other cutting edge that
extends toward the seating face. Alternatively, each of
the second cutting edges is concave away from the
seating face.
According to the invention, disclosed is a hard
wear resistant cutting insert. The insert has a top and
bottom parallel to the top joined by four lateral faces.
At least one of the lateral faces is a clearance face.
The clearance face has a first cutting edge which is
formed by the intersection of the top and the clearance
face. The clearance face also has a second cutting edge
intersecting the first cutting edge at an included angle
of greater than 90 degrees when viewed perpendicularly
to the clearance face. The second cutting edge is
formed by the intersection of a rake face of the second
cutting edge and the clearance face. The rake face is
defined by a plane which intersects the clearance face,
one of said lateral faces and the top. This plane is
not perpendicular to either of the clearance face,
lateral face or top so that a flat is formed extending
away from the second cutting edge~
Preferably, the insert is indexable.
In a further embodiment, the insert is preferably in
the shape of a diamond when viewed in plan with the
smaller of the included angles of the diamond being
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between 75 degrees and 85 degrees. In another embodi-
ment, the insert is in the shape of a s~uare when viewed
in plan.
The second cutting edge may comprise a plurality of
cutting segments The orientation of each of the seg-
ments differs in orientation from the previous cutting
segment so that when viewed perpendicularly to the clear-
ance face the included angle between the first of the
segments and the first cutting edge and the included
angle between each subsequent cutting segment and the
previous cutting segment is greater than 90 degrees.
Each of the segments has a rake face which differs in
orientation, corresponding to the differences in
orientation of each of the segments. Each of the rake
faces intersects the rake faces on either side thereof.
The lines of intersection formed by the rake faces all
converge to a point away from the segments.
In another embodiment, the second cutting edge has a
concave portion and a corresponding concave axial rake
face. The concave portion and axial rake face form a
groove which narrows in depth and width away from the
concave cutting portion.
BRIEF DESCRIPTION OE THE DRAWINGS
The exact nature of the present invention will
become more clearly apparent upon reference to the
following detailed specification taken in connection with
the accompanying drawings in which:
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Figure 1 is a side view of the drill according to
the present invention
Figure 2 is an end view of the drill in Fi~ure 1.
Figure 3 is a schematic illustration of a hole made
by a drill according to the invention.
Figure 4 is an enlarged view of Figure 2.
Figure 5 is a side view of another embodiment of the
drill according to the invention.
Figure 6 is a perspective view of an insert accord-
ing to the invention.
Figure 7 is a plan view of the insert of Figure 6.
Figure 8 is a view of Figure 7 in the direction
shown by arrow VIII.
Figure 9 is a perspective view of another insert
according to the invention.
Figure 10 is a plan view of the insert of Flgure 9.
Figure 11 is a view of Figure 10 in the direction of
arrow XI.
Figure 12 i6 a perspective view of another insert
according to the invention.
Figure 13 is a plan view of the insert of Figure
12.
Figure 14 is a view of Figure 13 in the direction of
arrow XIV.
Figure 15 is a perspective view of another insert
according to the invention.
Figure 16 is a plan view of the insert of Figure
15.
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Figure 17 is a view of the insert of Figure 16 in
the direction of arrow XVII.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings somewhat more in detail,
according to the invention there is disclosed a drill 2
as shown in Figures 1 and 2. The drill has a shank 4
having a central axis of rotation 6. The direction of
rotation is shown by arrow 7. There is only one insert 8
on one end 10 of the shank. The insert has two cutting
edges 12 and 14. The first cutting edge 12 has a nega-
tive radial rake surface and the second cutting edge 14
has negative axial and positive radial rake surfaces.
The first and second cutting edges cooperate to form a
radiused hole when rotated about the central axis.
The operation of the drill according to the inven-
tion can best be understood by referring to Figure 3.
Figure 3 schematically illustrates a hole 16 being
drilled hy the drill according to the invention. The
first cutting edge removes the outer portion 18 of the
hole while the second cutting edge removes the inner
portion 20 of the hole. The second cutting edge must be
located slightly away from the axis of rotation so that
there is never a point of zero velocity on the second
cutting edge. Since the second cutting edge is slightly
removed from the axis of rotation, a small nib 22 is left
after each rotation of the drill. However, in the prac-
tical application of the drill, this nib would frequently
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break off during the drilling operation so as not to be
evident in the finished hole.
According to the invention, there is disclosed
another embodiment of the drill. There is a shank 4
haviny a central axis of rotation 6. ~here is at least
one insert ~ on one end 10 of the shank. For larger
holes, the use of two or more inserts may be preferable.
The insert has two cutting edges 12 and 14~ The first
cutting edge 12 has a negative radial rake surface and
the second cutting edge 14 has negative axial and posi-
tive radial rake surfaces. The first and second cutting
edges cooperate to form a radiused hole when rotated
about the central axis.
This invention has been found to be most useful for
drilling holes less than one inch in diameter and
especially useful for drilling holes less than one-half
inch in diameter. It is contemplated within the scope of
this invention that this drill may also be used for holes
larger than one inch in diameter.
Preferably, the central axis of rotation 6 passes
through the axial rake face 24 of the second cutting edge
14.
It is preferred that the first cutting edge has 2ero
axial rake or positive axial rake.
Most preferably, the insert is indexable.
In a preferred embodimentl and as best shown in
Figure 1, the first cutting edge 12 is substantially
perpendicular to the central axis of rotation 6 so that a
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hole with a substantially flat bottom is formed. It had
previously been thought to be impossible to drill a flat
bottom hole. However, according to the invention, a flat
bottom hole is easily drilled.
~ eferring now to Figure 7, the insert is preferably
in the shape of a diamond when viewed in plan and the
smaller of the included angles at 26 of the diamond is
between 7~ degrees and 85 degrees. Normally, there will
be two cutting positions on the insert at 28 and 30.
Referring now to Figures 5 and 10, there is another
embodiment of the drill 2 wherein the insert ~ is in the
shape of a square when viewed in plan. The advantage of
using a square insert is that four cutting positions 34,
36, 38 and 40 are now possible.
It should be noted that a flat bottom hole is no
longer possible when a square insert is used. The reason
is that a clearance angle is needed on the outside of the
insert so that the side of the insert does not rub
against the wall of the hole. To obtain this clearance
angle, the insert must be tilted slightly, with the
result that the first cutting edge would no longer be
perpendicular to the axis of rotation.
Referring back to Fiyures 1 and 2, the shank prefer-
ably has a reduced diameter portion 42. The insert is
disposed on the end 10 of the reduced diameter portion of
the shank.
The insert is held to the shank by fastening means
44 passing through a perforation 46 in the insert. The
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fastening means terminates in a recess 94 in the shank.
The fastening means may be any of those well known in the
prior art.
As can he seen most clearly in Figures 6 through 8,
the second cutting edge axial rake face 24 extends out-
wardly with respect to the insert so as to break out of
said insert at 48.
In another embodiment of the drill, as can be seen
in Figures 12 through 14, the insert 8 has at least one
other cutting edge 50. This cutting edge has negative
axial and positive radial rake surfaces. The at least
one other cutting edge cooperates with the first and
second cutting edges to form a radiused hole when rotated
about the central axis.
Referring now to Figures 15 ~hrough 17, there is a
further embodiment of the drill wherein the second cut-
ting edge 14 is concave 52.
According to the invention, disclosed is a drill as
can be seen in Figures 1 and 2, but can be best seen in
Figure 4. The drill has a shank 4 and the shank has a
central axis of rotation 6. The direction of rotation is
shown by arro~ 7. There is only one cutting insert 8
disposed on the end 10 of the shank. As shown in Figure
4, the insert has first and second cutting edges 12 and
14, respectively, and clearance face 54. The first cut-
ting edge 12 extends inwardly and parallel to a plane 56
containing the axis of rotation. The plane rotation.
The plane 56 is positioned so as to be perpendicular to
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the plane of the paper. The second cutting edge 14
extends inwardly from the first cutting edge and when
viewed from the end forms an included angle 58 of greater
than 90 degrees therewith. The first and second cutting
edges are oriented along the forward portion 60 in the
rotational sense of the clearance face 54. The clearance
face intersects the plane 56 without intersecting the
axis of rotation. The intersection of the clearance face
and the plane is along a line that would be drawn from 62
to 64. The first and second cutting edges cooperate so
as to rotatably cut a hole.
The operation of the drill according to the inven-
tion is schematically illustrated in ~igure 3. Hole 16
is being drilled with outer portion 18 of the hole being
removed by the first cutting edge and the inner portion
20 of the hole being removed by the first cutting edge.
In order for the objects of the invention to be achieved,
the second cutting edge is located slightly off center so
as to avoid any point of zero velocity. Because the
second cutting edge is located sllghtly off center, ~ou
get nib 22, which is broken off periodically during the
operation of the drill.
According to the invention, there is disclosed a
drill 2 as can also be seen in Figures 1 and 2. There is
a shank 4 having a cental axis of rotation 6. There is
at least one cutting insert 8 disposed on the end 10 of
the shank. For larger holes, it may be preferable to
have two or more inserts located on the end of the shank.
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For larger holes, it may be preferable to have two or
more inserts located on the end of the shank. Referring
now to Figure 4, the insert has first and second cutting
edges 12 and 14, respectively, and a clearance face 54.
The first cutting edge 12 extends inwardly and para:Llel
to a plane 56 containing the axis of rotation. This
plane 56 is perpendicular to the plane of the paper. The
second cutting edge 14 extends inwardly from the first
cutting edge and when viewed from the end forms an
included angle 58 of greater than 90 degrees therewith.
The first and second cutting edges are oriented along the
forward portion 60 in the rotational sense of the clear-
ance face 54. The clearance face intersects the plane 56
without intersecting the axis of rotation. The first and
second cutting edges cooperate so as to rotatably cut a
hole.
The preferred use of this invention is for holes
less than about one inch in diameter, in which case one
insert would preferably be used. However, drilled holes
greater than about one inch in diameter are also contem-
plated within the scope of the invention~ In this latter
case, it may be found to be preferable to use two or more
inserts.
The second cutting edge has a rake face 24 and,
preferably, the axis of rotation 6 passes through the
rake face.
Preferably, the first cutting edge has a negative
radial rake surface and the second cutting edge has
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negative axial and positive radial rake surfaces. The
first cutting edge also has a zero axial rake or positive
axial rake. Preferably, the insert is indexable.
In a preferred embodiment, the first cutting edge 12
is substantially perpendicular to the axis of rotation 6
so that a hole with a substantially flat bottom is
formed. In the prior art, it was thought to be impossi-
ble to get a flat bottom hole; however, such a hole is
found to be achievable according to the invention.
As can be seen in Figures 1 and 7, the insert 8 is
in the shape of a diamond when viewed in plan and the
smaller of the included angles at 26 of the diamond is
between 75 degrees and 85 degrees. Normally, with such
an insert shape, there would be two cutting positions
located at 28 and 30.
In another embodiment, as shown in Figures 5 an 10,
the insert 8 is in the shape of a square when viewed in
plan. With this type of insert, it is possible to have
four cutting positions with each cutting position located
at the corners 34, 36, 38 and 40 of the square. Because
of the clearance angles required on the outside of the
insert, the insert must be tilted slightly. Accordingly,
a flat bottom hole is no longer possible with a s~uare
insert.
The shank has a reduced diameter portion 42. The
insert is disposed on the end 10 of the reduced diameter
portion of the shank.
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The insert is held to the shank by fastening means
44 passing through a perforation 46 in the insert. The
fastening means terminates in a recess 94 in the shank.
The drill preferably comprises means 66 for supply-
ing coolant. The coolant means are internal to the shank
and exit the shank at the end 10 of the reduced diameter
portion.
In another embodiment, as shown in Figures 12
through 14, the second cutting edge is comprised of a
plurality of cutting segments. As shown in the figures,
there is one additional segment 50, but it is contem-
plated within t~e scope of the invention that there may
be several such segments. The orientation of each of the
segments differs in orientation rom the previous cutting
segment so that when viewed from the end the included
angle 58 between the first of the segments and the first
cutting edge and the included angle 68 hetween each sub~
sequent cutting segment and the previous cutting segment
is greater than 90 degrees.
A further embodiment is now shown in ~igures 15
through 17. In this embodiment of the drill, the second
cutting edge 14 is substantially concave as shown by 52.
The concave cutting edge 52 and its axial rake face 70
form a groove which narrows in depth 72 and width 74 away
from the concave cutting edge 52.
According to the invention, there is a cutting
insert disclosed as shown in Figures 6 through 8. The
insert is comprised of a body of hard wear resistant
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material having top 76 and bottom 78 faces and a peri-
pheral wall 80 joining the top and bottom faces. The
hard wear resistant material is preferably cemented
carbide. The body is polygonal when viewed in plan. One
of the top and bottom faces acts as a seating face and
the other acts as a cutting face. First cutting edges 12
are formed on opposite sides of the cutting face at the
juncture of the cutting face with the peripheral wall.
One end of each of the first cutting edges terminates in
a jt~ncture 82 with a second cutting edge 14 that extends
from the cutting face toward the seating face. The first
and second cutting edges cooperate to form a radiused
hole when rotated about a central axis.
Each of the second cutting edges has a rake face 24
which extends upwardly away from the bottom face so that
it breaks out through the cutting face at 48.
It is preferable that the insert is indexable.
Preferably, the insert is in the shape of a diamond
when viewed in plan and the smaller of the included
20 angles at 26 of the diamond is between 75 degrees and 85
degrees. As shown in the figures, there would normally
be two cutting positions located at 28 and 30.
Referring now to Figures 9 through ll, the insert
may be in the shape of a square when viewed in plan.
When the insert has a square shape, there would normally
be four cutting pGsitions located at each corner of the
square.
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In another embodiment of the insert, as shown in
Figures 12 through 14, each of the second cutting edges
14 joins with at least one other cutting edge 50 that
extends toward the seating face.
In a further embodiment, as shown in Figures 15
through 17, each of the second cutting edges 1~ of the
insert is concave away from the seating face.
According to the invention, there is disclosed a
hard wear resistant cutting insert. The hard wear
resistant material is preferably cemented carbide. As
best seen in Figures 6 through 8, there is a top 76 and a
bottom 78 parallel to the top joined by four lateral
faces 80. At least one of the lateral faces is a clear-
ance face 54. The clearance face has a first cutting
edge 12 which is formed by the intersection of the top 76
and the clearance face 54. There is a second cutting
edge 14 intersecting at 82 the first cutting edge at an
included angle 58 of greater than 90 degrees when viewed
perpendicularly to the clearance face. The second cut-
ting edge is formed by the intersection of a rake face 24of the second cutting edge and the clearance face. The
rake face is defined by a plane which intersects the
clearance face at 14, one of the lateral faces at 84 and
the top at 86. This plane is not perpendicular to either
of the clearance face, the one of the lateral faces or
the top so that a flat is formed extending away from the
second cutting edge.
Most preferably, the insert is indexable.
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Preferably~ the insert is in the shape of a diamond
when viewed in plan and the smaller of the included
angles at 26 of the diamond is between 75 degrees and 85
degrees. With a diamond shape, there would normally be
two cutting positions.
Preferably, also, the insert is in the shape of a
square when viewed in plan, and there would normally be
four cutting positions.
In another embodiment of the insert, as shown in
Figures 12 through 14, the second cutting edge comprises
a plurality of cu~ting segments. The orientation of each
of the segments differs in orientation from the previous
cutting segment so that, when viewed perpendicular to the
clearance face 54, the included angle 58 between the
first 14 face segments and the first cutting edge 12 and
the included angle 6g between each subsequent cutting
segment 50 and the previous cutting segment is greater
than 90 degrees. Each of the segments has a rake face 88
and 90 which differs in orientation corresponding to the
differing in orientation of each of the segments 14 and
50, respectively. Each of the rake faces intersects the
rake faces on either side thereof. As shown in the
figures, rake faces 88 and 90 would intersect at 92. The
lines of intersection formed by the rake faces all con-
verge to a point 48 away from the segments.
In a further embodiment of the insert, as shown in
Figures 15 through 17, the second cutting edge 14 has a
concave portion 52 and a corresponding concave axial rake
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face 70. The concave portion and the axial rake face
form a groove which narrows in depth 72 and width 74 away
from the cutting force.
Modifications may be made within the scope of the
appended claims.
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