U.S. patent application number 11/002664 was filed with the patent office on 2005-08-25 for indexable cutting inserts and methods for producing the same.
This patent application is currently assigned to Sandvik AB. Invention is credited to Lindholm, Mikael, Sjogren, Clas E..
Application Number | 20050183893 11/002664 |
Document ID | / |
Family ID | 36565329 |
Filed Date | 2005-08-25 |
United States Patent
Application |
20050183893 |
Kind Code |
A1 |
Sjogren, Clas E. ; et
al. |
August 25, 2005 |
Indexable cutting inserts and methods for producing the same
Abstract
A method of making a cutting insert includes: (i) forming a
blank having a substrate and superhard material, the substrate
having more than 4 pockets, the superhard material disposed within
the pockets; (ii) removing cutting tips from the blank by cutting
the blank along cutting lines; (iii) providing a cutting insert
body having a plurality of cavities for receiving a corresponding
number of cutting tips; (iv) inserting a cutting tip into each of
the plurality of cavities; and (v) brazing the cutting tips to the
cutting insert body. A related cutting insert includes: a cutting
insert body having a plurality of cavities formed therein; a
plurality of cutting tips, each of the plurality of cutting tips
disposed in a respective cavity, the cutting tips having a geometry
that provides a mechanical retention or lock when inserted into the
cavities of the cutting insert body, said geometry including a
generally trapezoidal anchor portion with its base substantially
flat and spaced away form the cutting edge of the body, the cutting
tips further being brazed in the cutting insert body.
Inventors: |
Sjogren, Clas E.; (West
Midlands, GB) ; Lindholm, Mikael; (Hagersten,
SE) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
Sandvik AB
Sandviken
SE
|
Family ID: |
36565329 |
Appl. No.: |
11/002664 |
Filed: |
December 3, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11002664 |
Dec 3, 2004 |
|
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|
10918391 |
Aug 16, 2004 |
|
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Current U.S.
Class: |
175/426 ;
76/108.4 |
Current CPC
Class: |
B23B 2226/315 20130101;
B22F 5/003 20130101; B23B 2240/11 20130101; B23P 15/28 20130101;
B22F 2005/001 20130101; B23B 2215/68 20130101; B22F 2998/10
20130101; C22C 26/00 20130101; B23B 2226/125 20130101; B22F 7/06
20130101; B22F 5/003 20130101; B23B 51/00 20130101; B22F 7/06
20130101; B23B 2200/201 20130101; B22F 2998/10 20130101; B23B
2240/21 20130101; B22F 7/06 20130101; C22C 2026/005 20130101; B23B
27/007 20130101; B23B 27/04 20130101; E21B 10/573 20130101; B23B
27/141 20130101; B22F 2998/00 20130101; B22F 2998/00 20130101; B23B
2226/18 20130101; B23B 2240/08 20130101 |
Class at
Publication: |
175/426 ;
076/108.4 |
International
Class: |
E21B 010/36 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 13, 2004 |
WO |
PCT/SE04/00028 |
Claims
What is claimed is:
1. A method of making a cutting insert, the method comprising: (i)
forming a blank comprising a substrate and superhard material, the
substrate having more than 4 pockets, the superhard material
disposed within the pockets; (ii) removing cutting tips from the
blank by cutting the blank; (iii) providing a cutting insert body
having a plurality of cavities for receiving a corresponding number
of cutting tips; (iv) inserting a cutting tip into each of the
plurality of cavities; and (v) brazing the cutting tips to the
cutting insert body.
2. The method of claim 1, wherein the cutting insert is
indexable.
3. The method of claim 1, wherein the blank is generally
disk-shaped.
4. The method of claim 1, wherein the blank has the shape of a
polygon.
5. The method of claim 1, wherein the blank is provided with a
through-hole.
6. The method of claim 1, wherein the pockets have an arcuate
shape.
7. The method of claim 1, wherein the substrate is provided with at
least 6 pockets.
8. The method of claim 1, wherein the substrate is provided with at
least 7 pockets.
9. The method of claim 1, wherein the substrate is provided with at
least 8 pockets.
10. The method of claim 1, wherein the substrate is provided with
at least 9 pockets.
11. The method of claim 1, wherein the substrate is formed from a
cemented carbide, cermet, or hard metal alloy.
12. The method of claim 11, wherein the substrate is formed of a
cemented carbide comprising WC and Co, the cemented carbide
comprising 10-20 weight % Co.
13. The method of claim 1, wherein step (i) further comprises
introducing the superhard material in the form of a powder into the
pockets.
14. The method of claim 13, wherein step (i) further comprises
pressing and sintering the blank thereby unifying the substrate and
superhard material.
15. The method of claim 13, wherein step (i) further comprises
introducing the superhard material in the form of pre-pressed green
bodies into the pockets.
16. The method of claim 15, wherein step (i) further comprises
sintering the blank thereby unifying the substrate and superhard
material.
17. The method of claim 1, wherein the superhard material comprises
cubic boron nitride or polycrystalline diamond.
18. The method of claim 17, wherein the superhard material further
comprises at least one of a nitride, carbonitride, oxide or boride
of a metal chosen from groups IVa-VIa of the Periodic Table.
19. The method of claim 17, wherein the superhard material
comprises a composite having a first phase comprising cubic boron
nitride or polycrystalline diamond particles and a second phase
comprising a metal, a metalloid, or alloys thereof.
20. The method of claim 1, wherein the blank comprises a top
surface and an opposing bottom surface, and the superhard material
extends from the top surface to the bottom surface.
21. The method of claim 1, wherein step (ii) comprises wire cutting
to remove the cutting tips from the blank.
22. The method of claim 1, wherein step (ii) comprises providing
the cutting tips with a geometry that provides a mechanical
retention or lock when inserted into the body of the cutting
insert, said geometry including a generally trapezoidal anchor
portion with its base substantially flat and spaced away from the
cutting edge of the body.
23. The method of claim 1 wherein the cutting tip is provided with
a generally dovetail shape.
24. The method of claim 23, wherein the cutting tip is provided
with a rounded forward nose and a pair of converging forward
surfaces that meet at the nose.
25. The method of claim 24, wherein at least the rounded forward
nose portion of the cutting tip comprises the superhard
material.
26. The method of claim 25, wherein the superhard material is
provided a leg length of at least 2 mm, the leg length being
defined as distance between a first point on one of the converging
forward surfaces where the superhard material is connected to the
substrate material, and a second point defined by the point of
intersection between two imaginary lines drawn along each of the
converging forward surfaces.
27. The method of claim 26, wherein the leg length is at least 3
mm.
28. The method of claim 24, wherein the cutting tip is provided
with a waisted section of reduced width.
29. The method of claim 28, wherein the waisted section comprises a
first pair of angled surfaces and a second pair of surfaces that
meet at the section of reduced width.
30. The method of claim 29, wherein the length of one surface of
said second pair of surfaces is different from the other of said
surfaces.
31. The method of claim 1, wherein the cutting insert body is
formed from a cemented carbide, cermet, or hard metal alloy.
32. The method of claim 31, wherein the cutting insert body is
formed of a cemented carbide comprising WC and Co, the cemented
carbide comprising 10-20 weight % Co.
33. The method of claim 1, wherein the cutting insert body is
provided in the form of a polygon, oval or circle.
34. The method of claim 1, wherein the cutting insert is provided
in the form of a polygon.
35. The method of claim 1, wherein the cavities are provided with a
geometry that is complimentary to the geometry of the cutting tips
received therein.
36. The method of claim 1, further comprising applying at least one
coating to at least a portion of the cutting tip and/or cutting
insert body.
37. The method of claim 1, further comprising forming a
chip-breaker structure on the cutting insert body.
38. The method of claim 1, comprising forming the cutting insert
body in the shape of a polygon, and providing no more than 2
cavities therein.
39. The method of claim 1, comprising forming the cutting insert
body in the shape of a polygon, and providing no more than 4
cavities therein.
40. A cutting insert comprising: a cutting insert body having a
plurality of cavities formed therein; a plurality of cutting tips,
each of the plurality of cutting tips disposed in a respective
cavity, the cutting tips having a geometry that provides a
mechanical retention or lock when inserted into the cavities of the
cutting insert body said geometry including a generally trapezoidal
anchor portion with its base substantially flat and spaced away
from the cutting edge of the body and further comprising a braze
joint between each of the cutting tips and the cutting insert
body.
41. The cutting insert of claim 40, wherein each of the cutting
tips comprises, at least in part, a superhard cutting material.
42. The cutting insert of claim 41, wherein each of the cutting
tips are entirely made of a superhard cutting material.
43. The cutting insert of claim 41, wherein the superhard material
comprises cubic boron nitride or polycrystalline diamond.
44. The cutting insert of claim 43, wherein the superhard material
further comprises at least one of a nitride, carbonitride, oxide or
boride of a metal chosen from groups IVa-VIa of the Periodic
Table.
45. The cutting insert of claim 40, wherein the superhard material
comprises a composite having a first phase comprising cubic boron
nitride or polycrystalline diamond particles and a second phase
comprising a metal, a metalloid, or alloys thereof.
46. The cutting insert of claim 40, wherein the cutting tip
comprises a top surface and an opposing bottom surface, and the
superhard material extends from the top surface to the bottom
surface thereby defining two cutting edges.
47. The cutting insert of claim 40, wherein the cutting tips have a
general dovetail shape.
48. The cutting insert of claim 47, wherein the cutting tip
comprises a rounded forward nose and a pair of converging forward
surfaces that meet at the nose.
49. The cutting insert of claim 48, wherein at least the rounded
forward nose portion of the cutting tip comprises the superhard
material.
50. The cutting insert of claim 49, wherein the superhard material
is provided with a leg length of at least 2 mm, the leg length
being defined as distance between a first point on one of the
converging forward surfaces where the superhard material is
connected to the substrate material, and a second point defined by
the point of intersection between two imaginary lines drawn along
each of the converging forward surfaces.
51. The cutting insert of claim 50, wherein the leg length is at
least 3 mm.
52. The cutting insert of claim 48, wherein the cutting tip is
provided with a waisted section of reduced width.
53. The cutting insert of claim 52, wherein the waisted section
comprises a first pair of angles surfaces and a second pair of
surfaces that meet at the section of reduced width.
54. The cutting insert of claim 51, wherein the length of one
surface of said second pair of surfaces is different from the other
of said surfaces.
55. The cutting insert of claim 40, wherein the base of each of the
cutting tips has a length different from the length of the base of
the other of the cutting tips.
56. The cutting insert of claim 40, wherein the cutting insert body
is formed from a cemented carbide, cermet, or hard metal alloy.
57. The cutting insert of claim 56, wherein the cutting insert body
is formed of a cemented carbide comprising WC and Co, the cemented
carbide comprising 10-20 weight % Co.
58. The cutting insert of claim 40, wherein the cutting insert body
is in the shape of a polygon, an oval or a circle.
59. The cutting insert of claim 58, wherein the cutting insert body
is in the shape of a polygon.
60. The cutting insert of claim 40, wherein the cavities have a
shape that is complimentary to the shape of the cutting tips.
61. The cutting insert of claim 40, wherein at least one of the
cutting tips and cutting insert body comprises a coating disposed
on at least a portion thereof.
62. The cutting insert of claim 40, wherein the cutting insert body
comprises a chip-breaker structure.
63. The cutting insert of claim 40, wherein the cutting insert
comprises no more than 2 cutting tips.
64. The cutting insert of claim 40, wherein the cutting insert
comprises no more than 4 cutting tips.
65. The cutting insert of claim 40, wherein the cutting tip is
arranged symmetrically about a bisector through a corner of the
insert.
66. The cutting insert of claim 40 wherein the cutting tip is
arranged asymmetrically about a bisector through a corner of the
insert.
67. The cutting insert of claim 40 wherein the cutting insert is a
turning insert.
68. The cutting insert of claim 40 wherein the cutting insert is
disposed on a drill.
69. The cutting insert of claim 68 wherein the cutting insert is
disposed substantially parallel to the central axis of the
drill.
70. The cutting insert of claim 68 wherein the cutting insert is
disposed substantially perpendicular to the central axis of the
drill.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part application of
U.S. patent application Ser. No. 10/918,391, filed Aug. 16, 2004
(Attorney Docket No. 024445-308).
FIELD OF THE INVENTION
[0002] The present invention relates to cutting inserts having
cutting edges formed from a superhard abrasive material, and
methods of making the same.
BACKGROUND OF THE INVENTION
[0003] In the description of the background of the present
invention that follows, reference is made to certain structures and
methods, however, such references should not necessarily be
construed as an admission that these structures and methods qualify
as prior art under the applicable statutory provisions. Applicants
reserve the right to demonstrate that any of the referenced subject
matter does not constitute prior art with regard to the present
invention.
[0004] Indexable cutting inserts typically have a polygonal shape
with a superhard material disposed generally at the corners. The
superhard material, often a cubic boron nitride or polycrystalline
diamond material, aids in the cutting of hard workpiece materials
such as metals. These cutting inserts are typically mounted in a
fixed position to a cutting tool so as to present one of the
corners or areas containing superhard material to the surface of a
workpiece. After being used for a period of time, the area of
superhard material becomes worm. The cutting insert can then be
unfastened from the cutting tool and rotated so as to present a new
fresh corner or area of superhard material to the surface of the
workpiece.
[0005] There are two predominant ways of making such inserts.
According to one technique, a stacked structure is formed
comprising a first layer of hard backing material and a layer of
superhard cutting material superimposed onto the backing layer.
Cutting tips are then cut from this stacked structure and brazed to
a cutting insert body, typically at a corner thereof. U.S. Pat. No.
5,183,362 to Kuroyama et al., the disclosure of which is
incorporated herein by reference, in its entirety, describes such a
technique.
[0006] However, several problems are associated with such
techniques. The braze joint connecting the cutting tips to the body
of the cutting insert creates an inherent weak point in the
structure. This is particularly true due to the high temperatures
that tend to exist during use of such cutting inserts, these high
temperatures being in close proximity to the braze joint. Another
problem posed by such techniques is that the extent of superhard
material presented to the workpiece and available for wear is
limited, thus limiting the useful operating period for that
particular cutting edge.
[0007] A second technique for forming indexable cutting inserts
involves providing a blank or substrate having pockets formed
therein which are filled with superhard material, then subjecting
the blank to a sintering operation which bonds the superhard
material to the substrate. The blank is then subsequently machined
to give the cutting insert its final shape, i.e.--a generally
polygonal body with superhard material disposed at the corners
thereof. U.S. Pat. No. 5,676,496, the disclosure of which is
incorporated herein by reference, in its entirety, describes such a
technique.
[0008] Such techniques also present certain difficulties. The
process by which the superhard material is bonded to the blank or
substrate is difficult and costly. In this regard, the cost of the
superhard and substrate raw materials are relatively minor when
compared with the costs associated with the process cycle necessary
to join them. Thus, from a production efficiency point of view it
would seem preferable to form an indexable insert with many corners
containing superhard material. That way, the number of costly
joining process cycles could be minimized while producing inserts
that had many cutting corners. However, customers of such cutting
inserts seem to strongly favor cutting inserts having relatively
few cutting corners, which are more costly to make on a per unit
basis using this technique. Most cutting inserts sold have only 2-4
cutting corners.
[0009] Another disadvantage associated with this second technique
is that if a single pocket of superhard material is defective, the
entire insert cannot be sold and may have to be scrapped. Yet
another disadvantage or inefficiency is that only a single cutting
insert is produced from each costly and difficult process
cycle.
[0010] French Patent Publication No. 2,691,657 discloses a cutting
insert made with a special autocentering shape made of
polycrystalline diamond, CBN or other cutting material. The insert
is clamped into the tip by a spring without brazing.
[0011] French Patent Publication No. 2,706,339, also an insert of
similar materials of a shape (including securing lugs) such that
the insert can be secured in the corresponding hole in the tip by a
mechanical wedging without brazing.
[0012] Thus, a need exists in the art to address the problems
discussed above and others.
SUMMARY OF THE INVENTION
[0013] The present invention provides devices and methods that
address the above-mentioned problems, and others.
[0014] The present invention provides improved indexable cutting
inserts and improved methods of producing the same.
[0015] According to one aspect, the present invention provides a
method of making a cutting insert which includes: (i) forming a
blank having a substrate and superhard material, the substrate
having more than 4 pockets, the superhard material disposed within
the pockets; (ii) removing cutting tips from the blank by cutting
the blank along cutting lines; (iii) providing a cutting insert
body having a plurality of cavities for receiving a corresponding
number of cutting tips; (iv) inserting a cutting tip into each of
the plurality of cavities; and (v) brazing the cutting tips to the
cutting insert body.
[0016] According to further aspect, the present invention provides
a cutting insert which includes: a cutting insert body having a
plurality of cavities formed therein; a plurality of cutting tips,
each of the plurality of cutting tips disposed in a respective
cavity, the cutting tips having a geometry that provides a
mechanical retention or lock when inserted into the cavities of the
cutting insert body, said geometry including a generally
trapezoidal anchor portion with its base substantially flat and
spaced away from the cutting edge of the body, and further
comprising a braze joint between each of the cutting tips and the
cutting insert body.
BRIEF DESCRIPTION OF THE DRAWING FIGS.
[0017] FIG. 1 is a top view of a blank or preform constructed
according to the principles of the present invention.
[0018] FIG. 2 is a top view of the blank of FIG. 1, but with the
pockets thereof filled with a superhard material, and cut lines for
removal of a plurality of cutting tips therefrom.
[0019] FIG. 3 is a top view showing details of the geometry of a
cutting tip formed according to the principles of the present
invention.
[0020] FIG. 4 is a top view of various cutting tips formed
according to the principles of the present invention.
[0021] FIG. 5 is a top view of a cutting insert body formed
according to the present invention.
[0022] FIG. 6 is a top view of an indexable cutting insert formed
according to the present invention.
[0023] FIG. 7 is a top view of an alternative indexable cutting
insert formed according to the present invention.
[0024] FIG. 8 is an image comparing a cutting insert formed
according to the present invention with a conventional cutting
insert.
[0025] FIGS. 9A and 9B are a top view of a threading and
thread-milling insert, respectively, formed according to the
present invention.
[0026] FIGS. 10A and 10B are top views of other types of threading
insert formed according to the present invention.
[0027] FIGS. 11A, B, C, D and E are top views of other inserts
formed according to the present invention.
[0028] FIGS. 12A and B are side cross-sectional view and top view,
respectively, of a drill formed according to the present
invention.
[0029] FIGS. 13A, B and C are side cross-sectional views of drill
configurations formed according to the present invention.
[0030] FIG. 14 is a representation of an insert which can be used
for internal turning formed according to the present invention.
[0031] FIGS. 15A and B are side views and top views of a slotting
or boring tool formed according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] Exemplary arrangements and techniques according to the
present invention will now be described by reference to the drawing
figures.
[0033] According to the present invention, a blank is formed from a
hard material and a superhard cutting material. The blank having a
number of pockets for receiving superhard cutting material and a
superhard cutting material therein. An illustrative embodiment of
such a blank is shown in FIG. 1. As shown in FIG. 1, the blank 10
comprises a substrate 12 of a hard material having a plurality of
pockets 14 formed therein. While the blank 10 is illustrated as
having a disk-like shape, other geometries are clearly possible,
such as a polygon. It is also possible to form a through-hole in
the blank 10, which may facilitate handling. Similarly, the pockets
14 may have a size, location, distribution, and number with differ
from the illustrated embodiment. For example, the pockets 14 are
shown as having a curved or arcuate shape. However, other shapes
are clearly contemplated, such as an oval or a polygon.
[0034] In the illustrated embodiment, eight pockets 14 are provided
in the substrate 12. Other numbers are clearly possible. As
previously discussed, it is an advantage of the present invention
to form the blank 10 with as many pockets 14 for receiving
superhard cutting material as is feasible. Thus, according to one
embodiment, the substrate has more than 4 pockets. According to a
further embodiment, the substrate has at least 6 pockets. According
to another embodiment, the substrate has at least 8 pockets.
[0035] While the illustrated embodiment shows an even number of
pockets that are symmetrically distributed. It is also within the
scope of the present invention to provide an odd number of pockets,
such as 7 or 9. It is also contemplated that the pockets can be
located in a pattern that is not symmetrical.
[0036] The substrate 12 is formed from any suitable hard material.
Examples of suitable materials include cemented carbides, cermets,
and hard metal alloys. One suitable composition is a WC-Co cemented
carbide having 10-20 weight % Co, and preferably having 15-17
weight % Co.
[0037] As shown in FIG. 2, a superhard material 16 is provided in
one or more, and preferably all, of the pockets 14. The superhard
material can comprise any suitable material chosen for its cutting
characteristics. The superhard material 16 can initially be
provided in the form of a powder. Alternatively, the superhard
material 16 can be pre-pressed green bodies.
[0038] The superhard material can comprise a boron nitride, such as
cubic boron nitride (CBN), or a diamond material such as
polycrystalline diamond (PCD). The CBN or PCD material may have
additions of other materials, such as carbides, nitrides,
carbonitrides, oxides, and/or borides of metals chosen from groups
IVa to VIa of the periodic table. The superhard material 16 can be
in the form of a composite of CBN or PCD particles forming a first
phase, and at least a second phase of a semiconductor (e.g.--Si),
metal (e.g.--Cu, Ti, Al), metalloid, or alloys thereof.
[0039] After the superhard material 16 is placed within the pockets
14, the blank 10 is then subjected to a suitable treatment to unite
the superhard material 16 and the substrate material 12. The
treatment can comprise a sintering type treatment performed at
elevated temperatures and pressures. When the superhard material is
initially in the form of a loose powder, a pressing operation may
be performed before or during the sintering treatment, as
described, for example, in U.S. Pat. No. 5,676,496. Examples of
suitable processes are described, for example, in U.S. Pat. Nos.
4,991,467 and 5,115,697, the disclosures of which are incorporated
herein by reference, in their entirety.
[0040] The superhard material 16 preferably extends continuously
from a top surface of the blank 10 (visible in FIGS. 1-2) to an
opposing bottom surface of the blank 10 (not visible in FIGS. 1-2)
and is attached to an edge surface of the substrate 12 defined by
the pockets 14.
[0041] After above-mentioned step of uniting the superhard material
16 to the substrate 12, material is then cut or otherwise removed
from the blank. For example, the blank 10 can be cut along lines
18, which define therein the contour of a cutting tip 20.
[0042] The cutting tips 20 can be removed by any suitable cutting
or material removal/separation procedure. Once such procedure is
wire cutting, such as EDM wire cutting.
[0043] The cutting tips are provided with a geometry that will
provide a particularly efficacious mechanical retention or lock
when placed within the body of an indexable cutting insert. A
mechanical retention or lock provides a certain amount of stability
for the insert within the tip. However, a much greater stability is
provided when the insert is also brazed into the body as will be
described in more detail. According to the illustrated embodiment,
a cutting tip 20 which is removed from the blank 10 includes a
rearward portion 21 which is shaped generally as a trapezoid with
its base 29 being substantially flat and spaced away from what will
be the cutting edge of the insert. This shape at the rear of the
cutting tip provides a substantial anchor for the cutting tip in
the cutting insert.
[0044] A specific illustrative example of this type of cutting tip
geometry comprehended by the present invention is illustrated in
FIG. 3. The geometry or shape of the cutting tip 20 illustrated in
FIG. 3 can be described as follows. A pair of converging forward
surfaces 22a and 22b meet at a forward nose 24, which is preferably
rounded. The nose 24 is presented to the workpiece during use of
the cutting tip. As illustrated in FIG. 3, a portion of the
surfaces 22a and 22b, and the nose 24 comprise superhard cutting
material 16. The extent of superhard cutting material 16 extending
from the apex of the nose 24 and back along surfaces 22a and 22b
corresponds to dimension "L", and can be termed the leg length.
According to one embodiment of the present invention, the dimension
L is at least 2 mm. According to another embodiment, the dimension
L can be at least 3 mm.
[0045] Moving in the direction away from the forward nose 24,
subsequent to the converging surfaces 22a and 22b is an area of
reduced width or a waisted section 25. The waisted section is
defined by a first pair of angled surfaces 26a and 26b, as well as
a second set of surfaces 28a and 28b. Surfaces 26a and 28a, as well
as 26b and 28b meet at the area of reduced width and define a
trough-like formation. As described in more detail below, surfaces
28a and 28b can be the same or different lengths. The cutting tip
also comprises the generally planar rear surface 29.
[0046] The particular design of the rearward portion, that is, the
generally trapezoidal shape with the generally planar rear surface
29 facing away from the cutting edge, provides a solid anchor for
the cutting insert within the tip.
[0047] FIG. 4 is illustrative of three alternative cutting tip
configurations: 20a, 20b and 20c. These cutting tip configurations
differ with respect to the amount of superhard material contained
therein, and consequently the leg length (L) thereof. Otherwise,
the shape and particularly the rearward portion of each is the same
as in FIG. 3. The amount of superhard material contained in the
cutting tip 20 can be varied by choosing the location of the
cutting lines 18 (FIG. 2), as well as by the size, configuration
and/or depth of the pockets 14 in the blank 10. As illustrated in
FIG. 4, a cutting tip 20c can be configured such that it is formed
entirely from superhard cutting material, or a cutting tip 20a can
be configured such that the superhard material in a relatively
minor component thereof.
[0048] The above-described cutting tips of the present invention
are affixed to the body of an cutting insert. One illustrative
example of an appropriate cutting insert body is shown in FIG. 5.
The illustrated cutting insert body 30 comprises a body 32 of hard
material provided with a suitable number of cavities 34, 35 for
receiving cutting tips 20. The cavities 34, 35 are preferably
provided with a shape or geometry that is complimentary to the
shape or geometry of the cutting tips disposed therein.
[0049] The body 32 is composed of any suitable hard material.
Examples of suitable materials include cemented carbides, cermets,
and hard metal alloys. One suitable composition is a WC-Co cemented
carbide having 10-20 weight % Co, and preferably having 15-17
weight % Co.
[0050] Numerous modifications to the illustrated example are
contemplated. For example, the illustrated blank 30 is generally in
the shape of a polygon or a diamond and is configured to receive
two identical cutting tips. However, the shape of the body can be
other polygonal shapes, an oval, or circular. The central through
hole 36, which can be used for a particular type of mounting, can
be omitted. The body 30 can be configured to receive more than two
tips. For example, up to four tips can be provided at each corner.
It is not necessary that the tips disposed in the body 30 be
identical to one another. The cutting tips and/or the body 30 may
be machined, prior to, and/or, subsequent to installation of the
cutting tips. The cutting insert body 30 and/or the cutting tip(s)
20 may be provided with one or more coating(s). Further, the body
30 may be provided with a "chip-breaker" configuration, such as
described in U.S. Pat. No. 5,569,000, the disclosure of which in
incorporated herein by reference, in its entirety.
[0051] FIG. 6 is an illustrative indexable cutting insert 60
comprising a cutting insert body 32 having cutting tips 20 retained
thereby. The cutting tips 20 can be affixed to the body 32 by any
suitable technique. Suitable techniques include soldering or
brazing. One such technique is described in U.S. Pat. No.
5,183,362, the disclosure of which is incorporated herein, by
reference, in its entirety. In the illustrated embodiment, the
cutting tips are affixed to the body 32 by a braze joint 40.
[0052] FIG. 7 is another illustrative embodiment of an indexable
cutting insert 70 formed according to the principles of the present
invention. The cutting insert 70 has cutting tips 20c configured as
described in connection with FIG. 4.
[0053] FIG. 8 is an image comparing a cutting insert 300 formed
according to the present invention, with a conventionally formed
cutting insert 1000. As illustrated in FIG. 8, the leg length of
the superhard material of the cutting insert 300 of the present
invention is significantly greater than the leg length of the
superhard material of the conventional cutting insert thereby
providing the possibility of increased useful service life of the
cutting tip.
[0054] FIG. 9A is an embodiment of the present invention of a
threading insert which can be used in turning operations. In this
instance, the cutting tip 20A is formed and inserted so that it
lays asymmetrically with respect to a bisector A-A of the corner of
the insert. For the embodiments of FIGS. 6 and 7, for example, each
cutting tip was located symmetrically with respect to a bisector of
the cutting edges of that insert.
[0055] FIG. 9B is an embodiment of the present invention of a
thread-milling insert. In this case, the cutting tip is
symmetrically arranged along the cutting edge. Also, in this
instance, the cutting tip can be formed of a generally trapezoidal
shape with the planar rear surface facing away from the cutting
edge with two anchor portions 21 to provide even greater locking
and retention. In FIG. 9A, only one such anchor portion 21 is shown
or generally needed.
[0056] FIG. 10A is another embodiment of a threading insert of the
present invention. Again, it can be seen that the cutting tip is
asymmetrical with respect to a bisector of the corner of the
cutting insert. In FIG. 10B, a similar insert is shown in which
each of the generally planar rear surfaces 29 are of different
lengths. The angled surfaces 28a and 28b of each cutting tip may be
the same or different from each other and from the corresponding
portion of the other cutting tips.
[0057] FIGS. 11 A-E show other embodiments of cutting inserts of
the present invention. FIG. 11A is a generally square (although it
could be rectangular) cutting insert with cutting tips arranged
asymmetrically with respect to a bisector of the corner of the
insert. FIGS. 11B and D are similar, triangularly shaped inserts in
which the cutting tips are arranged symmetrically (FIG. 11B) and
asymmetrically (FIG. 11D) with respect to a bisector of the corner
of the insert. FIGS. 11C and E are also similar parting-off type
tools again with the cutting tips arranged symmetrical and
asymmetrical to a bisector through the cutting edge.
[0058] FIG. 12 shows still another embodiment of the present
insertion. In this case, the cutting tip 52 is located in a drill
generally indicated as 50. As shown in FIG. 12A, the drill may have
a single cutting tip while the drill shown in FIG. 12B has 2
cutting tips 52 disposed on either side of the central axis of the
drill. Although not shown, the drill can have flutes and is
otherwise a conventional product. In FIG. 12A, the cutting tip is
arranged essentially parallel to a central axis of the drill while
in FIG. 12B, the cutting tips are disposed essentially
perpendicularly to that axis.
[0059] FIG. 13 represents side cross-sectional views of drills of
the present invention. For example, FIG. 13A is a view taken at
90.degree. from the left of FIG. 12A. FIGS. 13B and 13C also are
different views of the embodiment of FIG. 12B.
[0060] FIG. 14 represents another embodiment of the present
invention in which the surfaces 28a' and 28b' are of different
lengths and are thus asymmetrical. In this particular embodiment,
the insert can be used as a boring bar or for internal turning of a
piece.
[0061] FIG. 15A is a side view of an insert of the present
invention similar to FIG. 11C in which the insert is used as, for
example, a parting-off tool. The insert is held within a cavity
generally indicated as 60, which corresponds in shape to the anchor
portion of the insert, in a holder body 62.
[0062] The present invention and the above-described embodiments
thereof provide numerous advantages over conventional cutting
inserts and their methods of fabrication.
[0063] By forming a blank having a relatively large number of
pockets of superhard material, a relatively large number of cutting
tips can be produced by each costly and difficult
pressing/sintering process cycle, thereby providing an advantage in
terms of economy. By removing the tips from the blank and affixing
them to the body of a cutting insert, each cutting insert can have
a number of tips that is less that the number removed from the
blank. Thus, cutting inserts having a relatively few number of
cutting tips, for example 2-4 tips, can be manufactured provided to
meet the demands of the market, but retain the advantage of being
made in an economical manner. The manufacturing costs of producing
these indexable cutting inserts according to the method of the
present invention can be on the order of 50-60% less than the costs
of producing inserts according to the second technique described in
the Background of the Invention section herein.
[0064] The technique of the present invention also provides the
advantage of having an increased yield when compared to techniques
such as the second technique described in the Background of the
Invention section. When utilizing the technique of the present
invention, one defective superhard material pocket may result in
one cutting tip being scrapped. By comparison, a single defective
superhard material pocket in the second conventional technique
described herein can result in the entire cutting insert being
scrapped.
[0065] According to the present invention, the cutting tips are
provided with a geometry that positively locates the tip within the
body of the cutting insert upon assembly, thus eliminating the need
for complicated fixtures to hold the insert in place during
brazing. In addition, the geometry of the cutting tip provides for
mechanical retention within the body of the cutting insert in
addition to the retention provided by brazing.
[0066] A cutting tip formed according to the principles of the
present invention also facilitates the formation of a cutting tip
wherein the superhard material has a leg length that is greater
than that readily attainable by conventional techniques (e.g. 2-3
mm or more). Increased leg length provides more superhard material
available for machining the workpiece, thereby adding length to the
useful service life of the cutting tip. Moreover, the superhard
material of the cutting tip of the present invention extends from
the top surface thereof to the bottom surface, thereby providing a
first cutting edge surface on the top, and a second cutting edge
surface on the bottom of the cutting tip that can be accessed by
flipping the cutting insert over.
[0067] Additional advantages will be evident to those of ordinary
skill in the art. The described embodiments of the present
invention are intended to be illustrative rather than restrictive,
and are not intended to represent every possible embodiment of the
present invention. Various modifications can be made to the
disclosed embodiments without departing form the spirit or scope of
the invention as set forth in the following claims, both literally
and in equivalents recognized by law.
* * * * *