CUTTING INSERT AND MILLING CUTTER PROVIDED WITH THE SAME
Technical Field
[001] The present invention relates to a cutting insert having improved main cutting edges and a
milling cutter provided with the same
[002] Particularly, the present invention relates to a cutting insert and a milling cutter provided with
the same, wherein the main cutting edges of the cutting insert have a concavo-convex shape and
are asymmetrically configured. A plurality of cutting inserts are mounted in different orientations
so that the concavo-convex patterns of the main cutting edges are staggered with respect to each
other.
Background Art
[003] Generally, pluralities of cutting edges are assembled on a surface of a milling cutter to
machine a workpiece. Therefore, the effectiveness of the milling cutter depends on the cutting
depth and the shape of a cutting insert.
[004] Recently, the development of new machining tools has enabled the milling process to
realize high speed machining and high speed transfer machining. In addition to the introduction of
new tools, in order to improve productivity the cut depth has been increased, so a method for
removing chips has been widely used.
[005] A conventional cutting insert 1 comprises a total of six surfaces having front and back
surfaces 2 and 3 in a thicknesswise direction and upper, lower, left and right surfaces 4, 5,6 and
7 configured along the perimeters of the front and back surfaces 2 and 3. In addition, the cutting
insert 1 is provided with main cutting edges 8 positioned along the four sides of both the front and
back surfaces 2 and 3 of the cutting insert, and subsidiary cutting edges 9 which are located along
the two sides of both the upper and lower surfaces 4 and 5 thereof.
[006] If the entire length of a main cutting edge is used for cutting in order to increase the cutting
area when a workpiece is cut using such a cutting insert 1, there is a problem in that the cutting
resistance is increased thereby reducing the life of the cutting insert. Further, there is a problem
in that since an increase in vibration and noise is proportional to an increase in the cutting
resistance, the degree of machining for a workpiece may be reduced.
Disclosure
[007] Accordingly, the present invention has been conceived in order to solve the aforementioned
problems in the prior art. An object of the present invention is to provide a cutting insert, in which
the main cutting edges have concavo-convex portions and are asymmetrically configured, so that
the cutting resistance can be reduced.
[008] In addition, another object of the present invention is to provide a milling cutter, wherein the
cutting inserts of the present invention can be mounted so that the concavo-convex patterns of
the main cutting edges are staggered with respect to each other, thereby being economical and
making it easy to mount the cutting inserts.
[009] According to a first aspect of the present invention, a cutting insert is provided, which has a
hexahedral shape with front and back surfaces in a thicknesswise direction and upper, lower, left
and right surfaces along the perimeter of the front and back surfaces. The cutting insert is formed
with a coupling hole passing through the front and back surfaces, and includes main cutting edges
along both lengthwise edges of the front surface. The main cutting edges of the front surface have
concavo-convex shapes, and the concavo-convex shapes are staggered and asymmetrical with
each other.
[010] According to a second aspect of the present invention, a milling cutter is provided wherein a
plurality of the cutting inserts of the present invention are mounted to pockets formed on a side
surface of a main body of the milling cutter so that the concavo-convex shapes of the main cutting
edges are staggered with each other in upward and downward directions.
Description of Drawings
[011] Fig. 1 is a perspective view showing an example of a conventional cutting insert.
[012] Fig. 2 is a perspective view of a cutting insert according to the present invention.
[013] Fig. 3 is a front or rear view of the cutting insert according to the present invention.
[014] Fig. 4 is a view showing a milling cutter assembled with cutting inserts according to the
present invention.
[015] Fig. 5 is a view showing cutting inserts according to the present invention before being
assembled in the pocket of the milling cutter according to the present invention.
[016] Fig. 6 is a view showing the cutting operation being performed after the cutting inserts
according to the present invention are mounted so as to be staggered with each other.
[017] Fig. 7 is a view showing the cutting insert according to the present invention normally seated
in a pocket.
[018] Fig. 8 is a view showing the cutting insert according to the present invention abnormally
seated in the pocket.
[019] Fig. 9 shows a cutting insert according to another embodiment of the present invention.
[020] Fig. 10 shows a cutting insert according to a further embodiment of the present invention.
[021] Fig. 11 shows a cutting insert according to a still further embodiment of the present
invention.
Mode for Invention
[022] A cutting insert and a milling cutter according to the present invention will be described in
detail with reference to the accompanying drawings and following embodiments.
[023] Fig. 2 is a perspective view of a cutting insert according to the present invention, and Fig. 3
is a front or rear view of Fig. 2.
[024] As shown in the figures, a cutting insert 10 according to the present invention has a
rectangular hexahedral shape with front and back surfaces 11 and 12 in a thicknesswise direction
and upper, lower, left and right surfaces 13, 14,15 and 16 along the perimeters of the front and
back surfaces 11 and 12.
[025] In addition, the cutting insert 10 according to the present invention is formed with a coupling
hole 17 in the front and back surfaces 11 and 12, through which a coupling screw S passes.
[026] Further, the cutting insert 10 according to the present invention has two or four main cutting
edges for cutting a surface of a workpiece, and two or four subsidiary cutting edges for cutting an
orthogonal surface of the workpiece adjacent to the surface to be cut.
[027] The main cutting edges 18a, 18b, 18c and 18d may comprise the first and second main
cutting edges 18a and 18b which are located along the two lengthwise edges of the front surface
11 of the cutting insert 10, and may further comprise the third and fourth main cutting edges 18c
and 18d which are located along the two lengthwise edges of the back surface 12.
[028] According to the present invention, the main cutting edges 18a to 18d have wave-shaped
concavo-convex portions. As shown in Figs. 2 and 3, it is preferable that each of the main cutting
edges 18a, 18b, 18c and 18d have a wave shape as viewed in a thicknesswise direction of the
cutting insert, and have a linear shape as viewed in a widthwise direction of the insert body.
[029] Further, it is preferable that the wave shape be repeated and formed periodically with the
same size and shape. However, the wave shape may not be periodically repeated if necessary,
and a wave having a combination of various lines and curves may be allowed. The
aforementioned wave shape may cause the length of the cutting edge to be longer than that of a
cutting edge having a linear shape.
[030] According to a preferred embodiment, the concavo-convex shapes of the first and second
main cutting edges 18a and 18b are configured so as to be staggered with respect to each other
and to be asymmetrical with each other. The third and fourth main cutting edges 18c and 18d are
configured so as to be rotationally symmetrical with the first and second main cutting edges 18a
and 18b by 180 degrees with respect to a longitudinal central axis VS of the insert body. That is,
the front and back surfaces 11 and 12 are shaped so as to be interchangeable with respect to the
longitudinal central axis VS.
[031] Fig. 4 shows cutting inserts 10 according to the present invention mounted to a cutter main
body 20; and Fig. 5 is a front view showing the cutting inserts 10 before they are mounted to the
cutter main body 20.
[032] As shown in the figures, if a first cutting insert 10 according to the present invention is
mounted to the cutter main body 20 so that the first main cutting edge 18a of the cutting insert is
configured to be the active main cutting edge, an adjacent second cutting insert is mounted in the
cutter main body so as to be reversed by 180 degrees with respect to the central axis of the front
and back surfaces of the first cutting insert 10 so that the second main cutting edge 18b of the
adjacent second cutting insert is configured as the active main cutting edge. Accordingly, the
cutting inserts may be mounted so that the concavo-convex portions of the active main cutting
edges of two adjacent cutting inserts are alternately staggered with each other.
[033] Fig. 6 is a view showing the cutting operation being performed after the cutting inserts
according to the present invention are mounted so that the concavo-convex portions of the active
main cutting edges of the cutting inserts are staggered with respect to each other.
[034] As shown in Fig. 6, according to the aforementioned mounting method, a workpiece is
mostly cut by ridge portions of the main cutting edge in one cutting insert and relatively
insignificantly cut by valley portions thereof. However, a trailing cutting insert is mounted so that
the ridge and valley portions thereof are staggered with those of the leading cutting insert.
Accordingly, the portions insufficiently cut by the leading cutting insert may be complementarily
cut by the ridge portion of the trailing cutting insert, so that precise and uniform cutting can be
realized.
[035] According to the present invention, as shown in Fig. 5, the coupling hole 17 of the cutting
insert 10 is configured so as to be eccentric from the center of the insert body in a lengthwise
direction, so that it is possible to prevent a cutting insert mounting error when the active main
cutting edges of the respective cutting inserts are mounted so as to be alternately staggered with
respect to each other as described above.
[036] That is, if the coupling holes 17 of the respective cutting inserts 10 are configured so as to be
eccentric in the lengthwise direction, the position of the coupling holes 17 of the respective cutting
inserts 10 are alternately changed upwards and downwards when the cutting inserts 10 are
alternately normally and reversibly mounted with respect to each other.
[037] Accordingly, if a screw connection hole 22 formed in each pocket 21 of the cutter main body
20 according to the present invention is designed so as to be positioned corresponding to the
coupling hole 17, a mounting error can be prevented since the cutting insert 10 is precisely
mounted in the pocket 21 only when the position of the coupling hole 17 is identical to that of the
screw connection hole 22.
[038] However, since the mounting error cannot be completely prevented only by the
arrangement of the coupling hole 17 and the screw connection hole 22, it is preferable that a
configuration for preventing a mounting error, as a means of settling the problem, is provided
which comprises a convex portion 23 and a concave portion 19 respectively provided at the cutter
main body 20 and the cutting insert 10.
[039] Such a configuration for preventing a mounting error will be appreciated with reference to
Figs. 7 and 8.
[040] If the first main cutting edge 18a of one cutting insert, which is mounted in the normal
direction, is configured as the active main cutting edge, the second main cutting edge 18b of
another cutting insert, which is mounted in the reverse direction, should be configured as the
active main cutting edge. However, it is difficult to completely prevent the error that a cutting
insert is mounted in order for the third main cutting edge 18c to function as the active main cutting
edge only by means of the eccentric configuration of the coupling holes 17 and the screw
connection holes 22 as described above.
[041] Accordingly, the concave portion 19 is provided eccentrically in the lengthwise direction on
the left or right surface 15 or 16 of the cutting insert 10 according to the present invention, while
the convex portion 23 is provided on a mounting surface of the pocket 21 opposite thereto.
Accordingly, when the cutting insert is normally mounted, the convex portion 23 and the concave
portion 19 are aligned with each other as shown in Fig. 7, whereas when the cutting insert is
abnormally mounted, the convex portion 23 and the concave portion 19 are unaligned as shown
in Fig. 8 and thus cannot be smoothly mounted to each other, so that the mounting error can be
completely prevented.
[042] Figs. 9, 10 and 11 respectively show cutting inserts according to other embodiments of the
present invention.
[043] According to the figures, the main cutting edges of the cutting insert 10 according to the
present invention may be configured so as to have a square-wave type concavo-convex shape,
which is formed in the widthwise direction of the insert body, instead of the wave shape. Further,
as shown in Figs. 9 and 10, the main cutting edges may be formed on both the front and back
surfaces 11 and 12. Alternatively, as shown in Fig. 11, the main cutting edges may be formed on
any one of the front and back surfaces 11 and 12.
[044} in a first embodiment in which the main cutting edges 18a to 18d are configured so as to
have a square-wave type concavo-convex shape, as shown in Fig. 9, asymmetrical grooves h are
formed on the front and back surfaces 11 and 12 of the insert body in both sides of the coupling
hole 17. Here, the grooves h are gradually deeper from the coupling hole 17 towards the
widthwise edges of the front and back surfaces 11 and 12, so that the cutting edges having
concavo-convex shapes can be formed along the widthwise edges of the front and back surface
11 and 12.
[045] In a second embodiment in which the main cutting edges 18a to 18d are configured so as to
have a square-wave type concavo-convex shape, as shown in Fig. 10, asymmetrical grooves h
are formed on the left and right surfaces 15 and 16 of the insert body towards both sides with
respect to the longitudinal central axis of the left and right surfaces. Here, the grooves are
gradually deeper from the longitudinal central axis towards the thicknesswise edges, so that the
cutting edges having concavo-convex shapes can be formed along the thicknesswise edges of
the left and right surfaces.
[046] In a third embodiment in which the main cutting edges 18a and 18b are configured so as to
have a square-wave type concavo-convex shape, as shown in Fig. 11, the left and right surfaces
15 and 16 of the insert body are tapered in one direction, and grooves h are formed towards one
side with respect to the longitudinal central axis of the left and right surfaces. Here, the grooves
are gradually deeper from the longitudinal central axis towards the lengthwise edges, so that the
cutting edges having concavo-convex shapes can be formed along the side edges of the left and
right surfaces.
[047] If the grooves and the projections in the square-wave type concavo-convex portions as
described above are smoothly curved, they can be converted into the wave-shaped
concavo-convex portions.
[048] According to the present invention so described, main cutting edges are configured to have
concavo-convex shapes and be asymmetrical with each other, whereby the length of each main
cutting edge may be magnified. Further, the cutting inserts are mounted in different mounting
directions so that the concavo-convex patterns of the main cutting edges can be staggered with
respect to each other, whereby it is possible to realize the functional effects which would be
obtained by mounting two different types of cutting inserts.
[049]Further, a means for preventing a mounting error is provided, so that the mounting error of
the cutting inserts can be prevented when the cutting inserts are mounted in ordef for the main
cutting edges thereof to be staggered with each other, thereby providing a user with convenience.
[050] The aforementioned embodiments of the present invention are disclosed for illustrative
purposes only. It will be apparent to those skilled in the art that various modifications, changes
and additions thereto may be made within the spirit and scope of the invention. These
modifications, changes and additions will be included in the scope defined by the appended
claims.
We Claim:
1. A cutting insert, which has a hexahedral shape with front and back surfaces in a
thicknesswise direction and upper, tower, left and right surfaces along the perimeters of the front
and back surfaces, is formed with a coupling hole passing through the front and back surfaces,
and includes main cutting edges along both lengthwise edges of the front surface,
wherein the main cutting edges along both the lengthwise edges of the front surface have
concavo-convex shapes, and the two concavo-convex shapes are staggered and asymmetrical
with respect to each other.
2. The cutting insert as claimed in claim 1, further comprising main cutting edges positioned
along both lengthwise edges of the back surface, wherein the main cutting edges of the back
surface are rotationally symmetrical with those of the front surface by 180 degrees with respect to
a longitudinal central axis of the cutting insert.
3. The cutting insert as claimed in claim 1, wherein the concavo-convex shape is a wave or
square-wave type concavo-convex shape.
4. The cutting insert as claimed in claim 3, wherein the concavo-convex shape is formed in
a widthwise or thicknesswise direction of the cutting insert.
5. The cutting insert as claimed in claim 1, wherein the coupling hole is positioned so as to
be eccentric in a fengthwise direction from the center of the cutting insert.
6. The cutting insert as claimed in claim 1, wherein concave portions for preventing a
mounting error of the cutting insert are formed on the left and right surfaces of the cutting insert,
the concave portions being eccentric in a lengthwise direction from the center of the cutting insert.
7. A milling cutter,
wherein a plurality of the cutting inserts, each of which is claimed in any one of claims 1 to
6, are mounted in pockets formed on a side surface of the milling cutter so that the
concavo-convex shapes of the main cutting edges are staggered with respect to each other along
upward and downward directions.
8. The milling cutter as claimed in claim 7, wherein screw connection holes of the pockets to
which the cutting inserts are fixed are arranged so as to be staggered with respect to each other
along upward and downward directions.
9. The milling cutter as claimed in claim 7, wherein convex portions corresponding to the
concave portions for preventing a mounting error of the cutting inserts are arranged so as to be
staggered with respect to each other along upward and downward directions.

The present invention relates to a cutting insert having improved main cutting edges and
a milling cutter provided with the same.
In a cutting insert according to the present invention, main cutting edges positioned along
both lengthwise edges of a front surface have a wave shape and are asymmetrical with each
other, and other main cutting edges positioned along both lengthwise edges of a back surface are
rotationally symmetrical by 180 degrees from the main cutting edges of the front surface with
respect to a longitudinal central axis of the cutting insert.
In a milling cutter according to the present invention, the cutting inserts are alternately
mounted in pockets formed on a side surface of the milling cutter so that the concavo-convex
portions of the active main cutting edges of the cutting inserts which are adjacent to each other
are staggered with respect to each other.