U.S. patent number RE42,644 [Application Number 11/987,421] was granted by the patent office on 2011-08-23 for indexable cutting insert with chip breaker.
This patent grant is currently assigned to Seco Tools AB. Invention is credited to Mats Jonsson.
United States Patent |
RE42,644 |
Jonsson |
August 23, 2011 |
Indexable cutting insert with chip breaker
Abstract
The present invention relates to a cutting insert for chip
removing machining. The cutting insert has a substantially circular
cutting edge formed at a transition between an upper side and an
edge surface of the cutting insert. The upper side includes a chip
surface including at least one chip breaker portion and the edge
surface includes a clearance surface having an arrangement for
indexing the cutting insert. The chip breaker portion is provided
at varying distance from the associated cutting edge. The
arrangement is provided in a position relative to a reference line
or axis of the tool in order to orient the chip breaker portion in
the chip surface to a desired position.
Inventors: |
Jonsson; Mats (Hedemora,
SE) |
Assignee: |
Seco Tools AB (Fagersta,
SE)
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Family
ID: |
20290012 |
Appl.
No.: |
11/987,421 |
Filed: |
November 29, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/SE2003/002044 |
Dec 17, 2003 |
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Reissue of: |
11160348 |
Jun 20, 2005 |
7198437 |
Apr 3, 2007 |
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Foreign Application Priority Data
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Dec 20, 2002 [SE] |
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0203865 |
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Current U.S.
Class: |
407/115;
407/113 |
Current CPC
Class: |
B23B
27/1618 (20130101); B23C 2200/167 (20130101); B23B
2200/125 (20130101); Y10T 407/23 (20150115); B23B
2200/3627 (20130101); Y10T 407/245 (20150115); Y10T
407/24 (20150115); B23B 2205/16 (20130101); Y10T
407/235 (20150115); B23B 2260/0725 (20130101); B23B
2200/165 (20130101) |
Current International
Class: |
B26B
25/00 (20060101); B26B 27/00 (20060101) |
Field of
Search: |
;407/113,118,119,115 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Fridie, Jr.; Will
Attorney, Agent or Firm: WRB-IP LLP
Parent Case Text
The present application is a continuation of PCT/SE2003/002044,
filed Dec. 17, 2003, which claims priority of SE 0203865-1, filed
Dec. 20, 2002, both of which applications are incorporated by
reference.
Claims
What is claimed is:
1. A cutting insert for chip removing machining, comprising a
substantially circular cutting edge formed at a transition between
an upper side and an edge surface of the cutting insert, the
cutting edge comprising at least one cutting edge portion, the at
least one cutting edge portion extending along substantially an
entire length of the cutting edge, the upper side comprising a chip
surface including at least one chip breaker portion associated with
a corresponding cutting edge portion and the edge surface
comprising a clearance surface, the edge surface connecting to a
lower side of the cutting insert, the lower side comprising means
for indexing of the cutting insert, wherein the at least one chip
breaker portion is provided at a varying distance from the
associated cutting edge portion over substantially an entire length
of the associated cutting edge portion, the indexing means is
provided at a position relative to a reference line or axis of the
tool in order to orient the chip breaker portion in the chip
surface to a desired position.
2. The cutting insert as set forth in claim 1, wherein the indexing
means includes a plurality of structures, and a quantity of chip
breaker portions is a multiple of a quantity of indexing means
structures.
3. The cutting insert according to claim 2, wherein the cutting
insert is single-sided, a plurality of chip breaker portions are
evenly radially spaced on the chip surface, and the indexing means
structures are evenly radially spaced on the lower side of the
cutting insert.
4. The cutting insert according to claim 3, wherein each chip
breaker portion comprises a ridge which follows a curved path
substantially in a direction toward a center of the cutting insert
and the cutting insert has a same quantity of indexing means
structures on the lower side of the cutting insert as a quantity of
chip breaker portions on the upper side.
5. The cutting insert according to claim 2, wherein each chip
breaker portion comprises a ridge which follows a curved path
substantially in a direction toward a center of the cutting insert
and the cutting insert has a same quantity of the indexing means
structures on the lower side of the cutting insert as a number of
chip breaker portions on the upper side.
6. The cutting insert according to claim 2, wherein each of the
indexing means structures is provided substantially midway between
two adjacent chip breaker portions when the cutting insert is seen
in a top view.
7. The cutting insert according to claim 2, wherein each of the
indexing means structures forms an acute angle with a centerline of
the cutting insert.
8. The cutting insert according to claim 2, wherein each of the
indexing means structures has a width in a plane of the lower side
that is no larger than a distance between two adjacent radially
external ends of the chip breaker portions.
9. The cutting insert according to claim 2, wherein a distance
between each chip breaker portion and the associated cutting edge
portion increases in a direction toward an adjacent chip breaker
portion.
10. The cutting insert according to claim 1, wherein the indexing
means includes a plurality of structures and each chip breaker
portion comprises a ridge which follows a curved path substantially
in a direction toward a center of the cutting insert and the
cutting insert has a same quantity of indexing means structures on
the lower side of the cutting insert as a quantity of chip breaker
portions on the upper side.
11. The cutting insert according to claim 4, wherein each of the
indexing means structures is provided substantially midway between
two adjacent chip breaker portions when the cutting insert is seen
in a top view.
12. The cutting insert according to claim 11, wherein each of the
indexing means structures forms an acute angle with a centerline of
the cutting insert.
13. The cutting insert according to claim 12, wherein each of the
indexing means structures has a width in a plane of the lower side
that is no larger than a distance between two adjacent radially
external ends of the chip breaker portions.
14. The cutting insert according to claim 13, wherein a distance
between each chip breaker portion and the associated cutting edge
portion increases in a direction toward an adjacent chip breaker
portion.
15. The cutting insert according to claim 1, wherein the indexing
means includes a plurality of structures and the cutting insert is
single-sided, a plurality of chip breaker portions are evenly
radially spaced on the chip surface, and the indexing means
structures are evenly radially spaced on the lower side of the
cutting insert.
16. The cutting insert according to claim 1, wherein the indexing
means includes a plurality of structures and each chip breaker
portion comprises a ridge which follows a curved path substantially
in a direction toward a center of the cutting insert and the
cutting insert has a same quantity of the indexing means structures
on the lower side of the cutting insert as a number of chip breaker
portions on the upper side.
17. The cutting insert according to claim 1, wherein the indexing
means includes a plurality of structures and each of the indexing
means structures is provided substantially midway between two
adjacent chip breaker portions when the cutting insert is seen in a
top view.
18. The cutting insert according to claim 1, wherein the indexing
means includes a plurality of structures and each of the indexing
means structures forms an acute angle with a centerline of the
cutting insert.
19. The cutting insert according to claim 1, wherein the indexing
means includes a plurality of structures and each of the indexing
means structures has a width in a plane of the lower side that is
no larger than a distance between two adjacent radially external
ends of the chip breaker portions.
20. The cutting insert according to claim 1, wherein a distance
between each chip breaker portion and the associated cutting edge
portion increases in a direction toward an adjacent chip breaker
portion.
Description
BACKGROUND AND SUMMARY
The present invention relates to a cutting insert, a cutting tool
for chip removing machining, a shim as well as a method for
mounting a cutting insert according to the preambles of the
independent claims.
In tools for metal machining round cutting inserts of hard and wear
resistant material such as cemented carbide are often used. A
problem, which is created at use of round cutting insert, is that
the cutting insert tends to be twisted arbitrary in the holder both
by the operator and by the cutting forces. Through a number of
documents, for example U.S. Pat. Nos. 6,146,060, 5,478,175,
3,383,748 and 5,346,336 different solutions are proposed in order
to lock the round cutting insert in the holder. Round cutting
inserts have a problematic chip-breaking pattern.
Round cutting inserts have, for example, a difficulty with breaking
chips at small cutting depths and at small feeds. There are,
however, round cutting inserts with chip breaker that to some
extent solve the later problem such as in U.S. Pat. Nos. 5,478,175
and 3,383,748. In U.S. Pat. No. 5,346,336 a circular cutting insert
is shown provided with five plane facets distributed at even
partition on the clearance surface. The facets are provided to
constitute defined positions in connection with indexing of the
cutting insert. Each facet forms an acute angle with the center
axis of the cutting insert. A locking screw locks the cutting
insert to the pocket of the holder insert. A problem with the
latter circular cutting insert is that it has difficulties to break
chips at small cutting depths and small feeds.
Other documents showing circular cutting inserts are JP Patent
Document No. 08-174311 and U.S. Pat. No. 6,164,878.
It is desirable to provide a cutting insert, which avoids the
above-captioned drawbacks.
It is also desirable to provide a cutting insert, which can break
chips at small cutting depths and small feeds.
It is also desirable to provide a cutting insert, which comprises a
built-in positioning of the chip breaker portion.
It is also desirable to provide a tool and a cutting insert that
comprise an adjustable chip breaker portion.
It is also desirable to provide a tool, a cutting insert, a shim
and a method, wherein the cutting insert can be indexed exactly in
a simple manner.
According to an aspect of the present invention, a cutting insert
for chip removing machining comprises a substantially circular
cutting edge formed at a transition between an upper side and an
edge surface of the cutting insert, the upper side comprising a
chip surface including at least one chip breaker portion and the
edge surface comprising a clearance surface, the edge surface
connecting to a lower side of the cutting insert, the lower side
comprising at least one of a projection and a recess for indexing
of the cutting insert. The chip breaker portion is provided at a
varying distance from the associated cutting edge, the at least one
of the projection and the recess is provided at a position relative
to a reference line or axis of the tool in order to orient the chip
breaker portion in the chip surface to a desired position, and a
quantity of chip breaker portions is a multiple of a quantity of
the at least one of the projection and the recess.
In accordance with another aspect of the present invention, a
circular shim for a cutting tool as described above is provided.
The shim is adapted to be placed in the at least one insert pocket
in order to support a circular cutting insert in the cutting tool.
The shim comprises opposite first and second surfaces and a central
hole. The first surface of the shim comprises an abutment surface
for abutting against the at least one insert pocket, and the second
surface of the shim comprises an abutment surface for abutting
against the circular cutting insert and at least one of a
projection and a recess for indexing of the cutting insert.
In accordance with another aspect of the present invention, a
method for mounting a cutting insert in a holder for chip removing
machining is provided. The cutting insert has a substantially
circular basic shape and comprises at least one cutting edge formed
at a transition between an upper side and an edge surface of the
cutting insert. The upper side comprises a chip surface comprising
at least one chip breaker portion and the edge surface comprising a
clearance surface. The cutting tool comprises a clamp for holding
the cutting insert and the holder together. The cutting insert has
at least one of a projection and a recess on its lower side.
According to the method, a holder including at least one insert
pocket with a base surface is provided. A circular shim is provided
in the insert pocket, the shim comprising opposite first and second
surfaces and a central hole, the first surface comprising an
abutment surface for abutting against the base surface, the second
surface comprising at least one of a projection and a recess for
mating with the at least one of the projection and the recess on
the lower side of the cutting insert. The cutting insert is
provided with a quantity of chip breaker portions that is a
multiple of a quantity of the at least one of the projection and
the recess on the lower side of the cutting insert. The shim is
screwed, with a screw, in position relative to the base surface
such that the shim can be rotated. The cutting insert is positioned
on the shim in such a manner that at least one of the at least one
of the projection and the recess on the lower side of the cutting
insert fits to a counterpart one of the at least one of the
projection and the recess on the second surface of the shim. The
cutting insert and the shim are rotated together until a desired
position for the chip breaker portion relative to the holder has
been obtained. The cutting insert is removed and the screw is
tightened such that the shim is fixed in a desired position. The
cutting insert is mounted in the position and the cutting insert is
fixed in the pocket by a clamping arrangement.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the cutting tool according to the present
invention is described below with reference to the enclosed
drawings, wherein:
FIG. 1A shows a top view of a cutting insert according to the
present invention;
FIG. 1B shows a side view of the cutting insert in FIG. 1A;
FIG. 1C shows a cross-section along line C D in FIG. 1A;
FIG. 1D shows an enlarged, partial cross-section along line D in
FIG. 1A;
FIG. 1E shows an enlarged, partial cross-section along line E in
FIG. 1A;
FIG. 1F shows an enlarged, partial cross-section along line F in
FIG. 1A;
FIG. 1G shows a perspective view from below of the cutting insert
according to FIG. 1A;
FIG. 2A shows a top view of a shim according to the present
invention;
FIG. 2B shows a cross-section along line B--B in FIG. 2A;
FIG. 2C shows a perspective view of the shim according to FIG.
2A;
FIG. 3 shows a perspective view of the cutting insert and the shim
in cooperation with each other;
FIG. 4 shows a tool according to the present invention in a
perspective view;
FIGS. 5A, 5B and 5C show the cutting insert according to the
present invention in a top view in different engagements with a
work piece;
FIGS. 6A 6C show an alternative embodiment of a cutting insert for
chip removing machining according to the present invention in a top
view, in a side view and in a perspective view, respectively;
and
FIGS. 7A 7C show an additional alternative embodiment of a cutting
insert for chip removing machining according to the present
invention in a top view, in a side view and in a perspective view,
respectively.
DETAILED DESCRIPTION
The cutting insert 10 in FIGS. 1A 1D has a substantially circular
basic shape and comprises an upper side 11, a lower side 12 and a
truncated, substantially conical, edge surface 13, which
substantially connects the upper 11 and lower sides 12. The cutting
insert 10 side 11 is shown as a grid, which is not visible on the
physical specimen of the cutting insert.
Said grid shall substantially be understood as altitude contour.
The cutting insert 10 is single-sided and has a positive geometry,
that is the edge surface 13 forms an inner acute angle with the
upper side 11. The upper side 11 comprises a chip surface 15 while
the edge surface 13 constitutes a clearance surface. The upper side
11 comprises a circular cutting edge 14, localized at the periphery
of the cutting insert 10. The chip surface 15 is substantially
concave and slopes radially inwardly and downwardly from the
cutting edge 14 and then rises above the plane of the cutting edge.
The cutting edge 14 is provided at the line of intersection between
the edge surface 13 and the chip surface 15 and constitutes the
most peripheral part of the upper side 11. The edge surface 13
coincides with a portion of an imaginary cone. The tip of the cone
intersects the centerline CL1 of the cutting insert below the lower
side 12.
In the shown embodiment the cutting insert 10 has been provided
with a fastening hole 17 intended to receive a fastening screw (not
shown) which shall secure the cutting insert 10 to the insert
holder.
The chip surface 15 comprises five chip breaker portions 18 or 18A,
18B, 18C, 18D, 18E provided at even partition, that is with
partition of 72.
The radially innermost parts of the chip breaker portion are
provided above the edge of the insert 14 planar. Each chip breaker
portion 18 extends with varying distance from the associated
cutting edge 14. Each chip breaker portion 18 comprises a ridge 19
that follows a curved path from about 0.02 mm from the periphery
and further in direction towards the fastening hole 17 of the
cutting insert. The ridge 19 successively rises in direction
towards the fastening hole 17. The curved path may be defined by a
radius of the same order of magnitude as the radius that defines
the periphery of the cutting insert. The radius center for the
curved path is provided within the periphery of the cutting insert.
Each chip breaker portion 18 preferably extends with continously
increasing distance from the associated cutting edge 14 in
direction towards an adjacent chip breaker, i.e. the ridge 19
becomes increasingly spaced from the cutting edge in direction
towards an adjacent chip breaker. Generally, the ridge 19 or a
tangent thereof forms an acute angle with the associated cutting
edge or a tangent thereof when the cutting insert is seen in a top
view. From FIGS. 1 D 1 E is apparent the position for the minimum
point of the chip surface 15 in different cross-sections. The
distance X indicates the radial distance between the minimum point
and the cutting edge 14, which distance is 1.49 mm, 0.72 mm
respective 0.14 mm in the shown the embodiment. The distance of the
ridge 19 from the associated cutting edge 14 is a function of the
distance X, that is, the distance of the ridge from the associated
cutting edge 14 in a cross-section is preferably bigger than 2
times X. Furthermore, the appearance of the chip surface on each
side of the ridge 19 is visible.
Alternatively, the radius center for the curved path can be
provided outside of the cutting insert periphery. Alternatively the
path can be parabolic or elliptical or similar. Alternatively, the
ridge 19 can be constituted by a number of from each other spaced
projections with substantially the same effect on the chip
breaking. Alternatively, 2 4 or 6 chip breaker portions can be
provided on the upper side at even partition, i.e. 180, 120, 90 and
60, respectively. A roughing insert with 2 3 chip breaker portions
is used for great cutting depths while a cutting insert with 6 chip
breaker portions is used for small cutting depths. Then the
roughing insert with 2 chip breaker portions preferably is provided
with a progressive reinforcing chamfer along the edge, that is a
chamfer whose width increases between two chip breaker portions in
the anticlockwise direction in FIG. 1A. Of course also the diameter
of the cutting insert decides the area of application.
The lower side 12 of the cutting insert comprises a number of
indexing portions 20 or 20A, 20B, 20C, 20D, 20E provided at even
partition, that is with a partition of 72, and intended for
indexing of the cutting insert. Each recess 20A 20E is made of a
radially extending groove, the extension line of that intersects
the centerline CL1 of the cutting insert.
The recess 20A 20E may start in the clearance surface 13 and
thereby have open ends such as FIG. 1G shows. The recess can
alternatively be developed with one or two closed ends. The
geometry of the groove is such that the strength of the cutting
insert is influenced as a little as possible, that is sharp corners
are avoided in the groove. Simultaneously it is desirable that the
groove also prevents a limited rotation of the cutting insert
relative to the projection of the shim. The recess 20A 20E is
provided substantially midways between two adjacent chip breaker
portions when the cutting insert is seen in a top view. Each recess
20 has a width in the plane of the lower side 12 or a plane
parallel thereto that is in the same order of magnitude as or less
than the distance between two adjacent radially external ends of
the chip breaker portions 18. In the shown embodiment the chip
breaker portions are rotated 36 relative to the indexing portions.
Alternatively, projections instead of recesses 20A 20E can be
provided on the lower side 12. Alternatively, 2 4 or 6 recesses or
projections can be provided on the lower side 12. A cutting insert
shall preferably have the same number of recesses on the lower side
of the cutting insert as the number of chip breaker portions on the
upper side.
In FIGS. 2A 2C a shim 21 according to the present invention is
shown. The shim 21 is circular and comprises opposite first 22 and
second 23 surfaces and a central hole 24. The surfaces 22,23 are
plane parallel in order to form plane surface abutments against the
insert pocket and the cutting insert. The shim has a cylindrical,
circumferential surface 25. The first surface or the lower side 22
is substantially parallel with the second surface or the upper side
23. The upper side 23 has a projection or a shoulder 26. The
projection 26 has a substantially radial dimension such that its
imaginary extension line intersects the centerline of the shim. The
projection geometry is such that it will prevent even a limited
rotation relative to the active, cooperating groove of the cutting
insert. The cross-section of the projection should consequently be
substantially complementary with the cross-section of the groove
but should have a height that is somewhat lower than the depth of
the groove in order to avoid tilting of the cutting insert.
Alternatively, 2, 3, 4 or 6 recesses instead of the projection 26
can be provided on the upper side 23 for the case 2, 3, 4 or 6
projections are provided in the lower side 12 of the cutting insert
at even partition, i.e. 180, 120, 90, 72 or 60.
With reference now to FIGS. 3 and 4 a cutting tool 30 according to
the present invention is shown. The cutting tool comprises a holder
31, which is a holder for a turning tool having a pocket 32 in
order to receive cutting inserts. The pocket comprises a
substantially planar base surface 33 and upright shoulders 34,35.
Each shoulder has an upper concave surface, provided to abut
against the edge surface 13 of the cutting insert. A threaded
boring is provided close but not in the base surface 33 center, in
order for a locking screw in a known manner to be able to force the
cutting insert against shoulders and the base surface 33. The shim
21 is provided to be fastened in a conventional manner by a locking
screw, not shown.
Such a locking screw has an external thread as well as an internal
thread in order to receive another screw for fastening the cutting
insert after the shim has been secured. Each recess 20A 20E is
provided in a position relative to a reference line or axis CL2 of
the tool, see FIG. 4, to orient the chip breaker portion 18A 18E in
the chip surface 15 to a desired position.
The tool's axis CL2 coincides with the bisector for an angle
between edges 31A and 31B of the holder that connect to the
shoulders 34,35 or with a normal to the center line CL1 of the
cutting insert. In a milling tool the axis CL2 is the rotational
axis of the tool. The number of chip breaker portions 18A 18E is a
multiple of the number of projections or recesses 20A 20E, wherein
the multiple preferably being integers of 1, 2, 3 or 4.
In a conventional holder the conventional circular shim is replaced
by a shim according to the present invention. The shim has a
central hole provided with a collar against which a screw is drawn
lightly. Thereby the shim can be rotated by hand. The cutting
insert according to the present invention is placed on the shim in
such a manner that some of the recesses 20A 20E in the lower side
12 of the cutting insert fits against the indexing projection of
the shim. In this position the cutting insert and the shim
continuously are rotated together until the desired position for
the chip breaker portion 18A 18E has been obtained. The desired
position of the projection should be as close as possible in line
with or parallel with the tool's axis CL2, in order to minimize
loads on the projection at the screw-tightening of the cutting
insert against the shim. The cutting insert is then removed and the
screw is tightened such that the shim is secured in desired
position. Then the cutting insert is mounted again in the
above-mentioned position and a means for fastening, such as a clamp
or another screw or a combination thereof, is tightened. Since the
chip breaker portions of the cutting insert are adapted to the
recesses 20A 20E in the lower side of the cutting insert and the
indexing projection 26 in the shim a new edge can be indexed into
position or the cutting insert can be replaced and obtain exact the
same chip breaking as the former worn-out cutting edge.
In addition, the cutting insert is fully utilized since the
indexing becomes more exact. The chip breaker portion 18A 18E is
developed to be able to increase or diminish tendency for chip
breaking, and thereby to be able to vary the cutting forces,
depending on how the shim and thereby the cutting insert initially
was positioned.
Thus the chip breaker portion 18A 18E is adjusted such as in FIG.
5A in order to obtain good chip breaking at turning with a little
cutting depth a.sub.p and/or low feed speed in the feed direction
F. The chip breaker portion 18A 18E is provided close to the active
part of the circular cutting edge 14, or as close as possible to
the rotational axis of the workpiece. This is a preferred position
also at turning of hard-to-break material. The chip breaker portion
18A 18E is adjusted such as in FIG. 5B in order to obtain good chip
breaking at turning with medium-sized cutting depth and/or
medium-sized feed speed. The chip breaker portion 18A 18E is
provided farther from the active part of the circular cutting edge
14, or farther from the rotational axis of the workpiece than in
FIG. 5A. The chip breaker portion is adjusted such as in FIG. 5C in
order to obtain good chip breaking at turning with great cutting
depth and/or high feed speed. The chip breaker portion is provided
farther from the active part of the circular cutting edge 14, or
farther from the rotational axis of the workpiece than in FIG. 5B.
A new chip breaker portion enters into position according to FIG.
5C, which gives a positive contribution as regards chip breaking at
heavier longitudinal turning with great cutting depth or at
planing/copying with feed motion in the feed direction F', that is
at least partially in radial direction. At machining against and of
a 90 corner, with an intermediate radius, a cutting insert having
four chip breaker portions can be used with advantage. Then the
same chip breaker adjustment at the longitudinal turning can be
obtained as at machining of an adjacent collar. The useable
interval for adjustment of the cutting insert is within about 40,
that is from 0 40, having the position according to FIG. 5A as
reference(0). The size of the interval for adjustment depends on
the number of chip breaker portions on the cutting insert.
An alternative embodiment of a single-sided cutting insert 10' for
chip removing machining is shown in FIGS. 6A 6C. The cutting insert
is intended to be supported by a conventional shim or by the base
surface of the insert pocket. The cutting insert 10' is circular
and comprises means, such as five planar facets 20' distributed at
even partition in the edge surface 13' for indexing of the cutting
insert in the holder, not shown. Facets are provided to constitute
defined positions in connection with indexing of the cutting
insert. Each facet forms an acute angle with the center axis of the
cutting insert. The cutting insert 10' has a substantially circular
cutting edge 14' formed at the transition between an upper side 11'
and the edge surface 13' of the cutting insert. The upper side 11'
comprises a chip surface 15' including at least one chip breaker
portion 18'. The edge surface 13' constitutes a clearance surface.
The edge surface 13' may have another geometry, for example convex
or concave in cross-section or may comprise recesses. The chip
breaker portion 18' is provided at varying distance from the
associated cutting edge 14'. Each facet 20' is provided in a
position relative to a reference line or axis of the tool, see FIG.
4, in order to orient the chip breaker portion 18' in the chip
surface 15' to a desired position. The cutting insert has a facet
for each chip breaker portion and the cutting insert thereby
obtains five fixed positions relative to the holder.
Each facet 20' has a width in the plane of the lower side 12' that
is in the same order of magnitude or less than the distance between
two adjacent radially external ends of the chip breaker portions
18'.
An additional alternative embodiment of a single-sided cutting
insert 10'' for chip removing machining, is shown in FIGS. 7A 7C.
The cutting insert is intended to be supported by a conventional
shim or by the base surface of the insert pocket. The cutting
insert 10'' is circular and comprises means, such as ten planar
facets 20'' distributed at even partition in the edge surface 13''
for indexing of the cutting insert in the holder, not shown. Facets
are provided to constitute defined positions in connection with
indexing of the cutting insert. Each facet forms an acute angle
with the center axis of the cutting insert. The cutting insert 10''
has a substantially circular cutting edge 14'' formed at the
transition between an upper side 11'' and the edge surface 13'' of
the cutting insert. The edge surface 13'' may have another
geometry, for example convex or concave in cross-section or
comprise recesses. The upper side 11'' comprises a chip surface
15'' including at least one chip breaker portion 18''. The edge
surface 13'' constitutes a clearance surface. The chip breaker
portion 18'' is provided at varying distance from the associated
cutting edge 14''. Each facet 20'' is provided in a position
relative to a reference line or axis of the tool, see FIG. 4, in
order to orient the chip breaker portion 18'' in the chip surface
15'' to a desired position. The cutting insert has two facets for
each chip breaker portion in order to enable two different
positions for the chip breaker relative to the holder. The cutting
insert thereby obtains ten fixed positions relative to the holder.
Each facet 20'' has a width in the plane of the lower side 12''
that is smaller than the distance between two adjacent radially
external ends of chip breaker portions 18''.
Thus the present invention relates to a tool and a cutting insert,
which can break chips at small cutting depths and at small feeds
with the aid of an adjustable chip breaker portion, wherein the
cutting insert simply can be exactly indexed. Furthermore, the
shown cutting insert can be used in a conventional holder with or
without conventional or a shim according to the present
invention.
Although the described embodiment of the invention relates to a
turning application the invention is also applicable on milling
tools where round cutting inserts are provided at the tool's
periphery. The cutting insert is shown here as a right-hand design,
but its geometry can of course be mirror-inverted and exhibit a
left-hand design.
In the present application, the use of terms such as "including" is
open-ended and is intended to have the same meaning as terms such
as "comprising" and not preclude the presence of other structure,
material, or acts. Similarly, though the use of terms such as "can"
or "may" is intended to be open-ended and to reflect that
structure, material, or acts are not necessary, the failure to use
such terms is not intended to reflect that structure, material, or
acts are essential. To the extent that structure, material, or acts
are presently considered to be essential, they are identified as
such.
The invention is in no manner limited to the described embodiments
above, but can be varied within the limits of the subsequent
claims.
Different combinations of the above-captioned cutting insert
geometries are conceivable.
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