U.S. patent application number 09/823942 was filed with the patent office on 2001-12-27 for cubic boron nitride flat cutting element compacts.
Invention is credited to Cheynet De Beaupre, Jerome J., Keshavan, Madapusi K., Miess, Daniel J., Russell, Monte E..
Application Number | 20010054332 09/823942 |
Document ID | / |
Family ID | 26889434 |
Filed Date | 2001-12-27 |
United States Patent
Application |
20010054332 |
Kind Code |
A1 |
Cheynet De Beaupre, Jerome J. ;
et al. |
December 27, 2001 |
Cubic boron nitride flat cutting element compacts
Abstract
Flat composite cutting elements are provided having a layer of
Cubic Boron Nitride comprising less than 80 volume percent Cubic
Boron Nitride sandwiched between two layers each made from a
material brazeable to carbide or steel.
Inventors: |
Cheynet De Beaupre, Jerome J.;
(Sandy, UT) ; Miess, Daniel J.; (Orem, UT)
; Russell, Monte E.; (Orem, UT) ; Keshavan,
Madapusi K.; (Sandy, UT) |
Correspondence
Address: |
CHRISTIE, PARKER & HALE, LLP
350 WEST COLORADO BOULEVARD
SUITE 500
PASADENA
CA
91105
US
|
Family ID: |
26889434 |
Appl. No.: |
09/823942 |
Filed: |
March 30, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60193864 |
Mar 30, 2000 |
|
|
|
Current U.S.
Class: |
76/108.1 |
Current CPC
Class: |
B22F 7/06 20130101; B32B
18/00 20130101; C04B 2237/361 20130101; C23C 30/005 20130101; B22F
2005/001 20130101; C04B 2237/363 20130101 |
Class at
Publication: |
76/108.1 |
International
Class: |
B21K 005/04 |
Claims
1. A cutting tool composite compact blade comprising: a first layer
formed from a material selected from the group consisting of
refractory metals and carbides of refractory metals selected from
the groups IVB, VB and VIB of the periodic table; a second layer
formed from a material selected from the group consisting of
refractory metals and carbides of refractory metals selected from
the groups IVB, VB and VIB of the periodic table; and a third layer
of ultra hard between the first and second layers, wherein said
third layer comprises less than 80% by volume CBN.
2. A composite compact blade as recited in claim 1 wherein the
first layer is formed from a refractory metal and wherein the
second layer is formed from a material selected from the group
consisting of carbides of refractory metals selected from the
groups IVB, VB and VIB of the periodic table.
3. A composite compact blade as recited in claim 1 wherein the
first layer is formed from a material selected from the group
consisting of carbides of refractory metals selected from the
groups IVB, VB and VIB of the periodic table and wherein the second
layer is formed from a material selected from the group consisting
of carbides of refractory metals selected from the groups IVB, VS
and VIB of the periodic table.
4. A composite compact blade as recited in claim 1 wherein the
first layer is formed from a refractory metal and wherein the
second layer is formed from a refractory metal.
5. A composite compact blade as recited in claim 1 wherein each of
the first and second layer comprises a binder phase in the range of
5% to 20% by volume.
6. A composite compact blade as recited in claim 1 wherein the
third layer comprises less than 40% by volume CBN.
7. A composite compact blade as recited in claim 1 wherein the
third layer further comprises a material selected from the group of
AlN, AlB.sub.2 and Tungsten Carbide in the range of about 10% to
15% by volume.
8. A composite compact blade as recited in claim 1 wherein the
third layer further comprises a second phase material in the range
of about 0 to 45% by volume.
9. A composite compact blade as recited in claim 8 wherein the
second phase material comprises a material selected from group
consisting of TiN, TiC, and TiCN.
10. A composite compact blade as recited in claim 8 wherein the
second phase material comprises a C:N ratio not greater than 1.
11. A composite compact blade as recited in claim 1 wherein the
first layer comprises a thickness and wherein the third layer
comprises a thickness and wherein the ratio of the thickness of the
first layer to the thickness of the third layer is in the range of
about 9:1 to about 36:1.
12. A composite compact blade as recited in claim 1 wherein the
third layer comprises a non-uniform face, facing toward the first
layer.
13. A composite compact blade as recited in claim 1 wherein the
first layer comprises a non-uniform face facing toward the third
layer.
14. A composite compact blade as recited in claim 1 wherein the
first and second layers each comprise a non-planar face, wherein
the non-planar face of the first layer faces toward the non-planar
face of the second layer.
15. A composite compact blade as recited in claim 1 wherein the
third layer comprises a first non-planar face facing toward the
first layer and a second non-planar face opposite the first
non-planar face facing toward the second layer.
16. A method for making a composite compact blade comprising a CBN
layer sandwiched between a refractory metal layer and a carbide
layer, the method comprising the steps of: providing a can made
from a refractory metal the can having an open end and a cover;
placing a layer of CBN in the can; covering the can open end with
the cover forming an assembly; and sintering the assembly for
forming the cutting element having a CBN layer and another layer
formed by a portion of the can.
17. A method as recited in claim 15 further comprising the step of
cutting the sintered assembly to remove portions of the sintered
can.
18. A method as recited in claim 15 wherein another portion of the
can forms another layer of refractory metal, wherein the two
refractory metal layers sandwich the CBN layer.
19. A method as recited in claim 15 further comprising the step of
providing a layer of a carbide material between the can and the CBN
layer, the carbide material selected from the group consisting of
carbides of a refractory metals selected from the groups IVB, VB
and VIB of the periodic table.
20. A method as recited in claim 15 wherein the refractory metal
can comprises a material selected from the group consisting of
refractory metals selected from the groups IVB, VB and VIB of the
periodic table.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims priority on U.S.
Provisional Patent Application No. 60/193,864 filed on Mar. 30,
2000, which is fully incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to flat cutting elements and more
specifically to flat composite cutting elements having an ultra
hard material layer, comprising less than 80 volume percent cubic
boron nitride, sandwiched between two outer layers of material.
Each of the two outer layers is be made from a material brazeable
to carbide or steel.
BACKGROUND OF THE INVENTION
[0003] Flat cutting elements are used in drill blanks or shafts of
flat drills or other cutting tools. Current flat composite elements
containing an ultra hard material layer sandwiched between two
layers of a refractory metal are typically brazed in drill blanks.
Once the cutting element is brazed, the drill body may be fluted
and shaped.
[0004] Typical flat composite elements comprise a layer of
polycrystalline diamond sandwiched between two layer of a
refractory metal. Other cutting elements have incorporated a
central layer of cubic boron nitride (CBN) containing more than 80%
by volume CBN and sandwiched between two layers of refractory
metal. However, forming a flat cutting element using CBN central
layer between two layers at least one of which is a carbide layer,
as for example a Tungsten Carbide layer, has been avoided because
the carbide layer tends to crack or delaminate from the CBN.
SUMMARY OF THE INVENTION
[0005] Flat composite cutting elements (also referred to herein as
"compacts" or blades") are provided for use in a drill blank or a
shaft of a flat drill or other cutting tool. An exemplary
embodiment inventive cutting element incorporates CBN sandwiched
between two layers, each layer made from a material selected from
the group comprising a carbide of a refractory metal selected from
the groups IVB, VB, and VIB of the periodic table, or any metal
that is brazeable to a carbide or steel, and any combinations
thereof. Less than 80% by volume of CBN is used to form the CBN
layer.
[0006] In a further exemplary embodiment, the flat cutting element
comprises a layer of CBN sandwiched between a layer made from a
material selected from the group comprising carbides of refractory
metals from the groups IVB, VB, and VIB of the periodic table, and
any combination thereof, and a layer of a refractory metal selected
from the groups IVB, VB, and VIB of the periodic table as for
example tungsten, niobium, tantalum or molybdenum. With this
embodiment, less than 80% by volume of CBN may be used to form the
CBN layer.
[0007] The CBN layer compositions may include second phase
materials such as TiN, TiC, TiCN ranging from 0-45 volume percent
and which have a C:N ratio less than or equal to 1. In addition
10-15 volume percent of the CBN layer composition may be a solution
of AlN, AlB2 or Co-Wc. Moreover, the CBN layer compositions may
include a binder phase in the range of 5% to 20% by volume.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of a exemplary embodiment flat
cutting element compact of the present invention.
[0009] FIG. 2 is a perspective view of the flat cutting element
disclosed in FIG. 1 incorporated in a slot of a standard drill
blank.
[0010] FIG. 3 is a cross-sectional view of a can including a stack
of components for forming an exemplary embodiment cutting element
of the present invention.
[0011] FIG. 4 is cross-sectional view of a can including a stack of
components for forming alternate exemplary embodiment cutting
element of the present invention.
[0012] FIG. 5 is a cross-sectional view of a can including a stack
of components used to form a further exemplary embodiment cutting
element compact of the present invention.
[0013] FIG. 6 is a cross-sectional view of a can including a stack
of components used to form another exemplary embodiment cutting
element compact of the present invention.
[0014] FIG. 7 is a cross-sectional view of a can including a stack
of components used to form a further exemplary embodiment cutting
element compact of the present invention.
[0015] FIG. 8 is a table depicting the feed compositions of various
CBN grades for forming a CBN layer used of a cutting element of the
present invention.
[0016] FIG. 9 is a cross-sectional view of another exemplary
embodiment flat cutting element compact of the present
invention.
DETAILED DESCRIPTION
[0017] The present invention relates to composite cutting elements
and specifically to flat composite cutting elements which are also
referred to herein as "compacts" or "blades". Flat composite
cutting elements are described in U.S. Pat. Nos. 4,906,528;
4,527,643; and 4,627,503 all three of which are fully incorporated
herein by reference. In an exemplary embodiment, an inventive
cutting element may be formed in any desired shape as for example a
flat chevron shape for forming the tip of drill bit. In other
exemplary embodiments, the inventive cutting element may be formed
as a flat rectangular piece 10 (FIG. 1). The rectangular cutting
element may be cut if necessary using EDM and other cutting methods
to any desired shape.
[0018] The inventive cutting element incorporates an ultra hard
material layer 16 comprising cubic boron nitride (CBN) sandwiched
between two layers 18, 20 (FIG. 1) of less hard material. For
convenience, the ultra hard material layer 16 is referred to herein
as the "CBN layer". The two layers of less hard materials are then
brazed onto the slot of the appropriate blank, as for example the
slot 12 of drill blank 14 shown in FIG. 2. Once the cutting element
is brazed, the blank may be fluted and shaped. In an exemplary
embodiment, the flat cutting element comprises a layer of CBN
sandwiched between two layers of Tungsten Carbide. In another
exemplary embodiment, the CBN layer is sandwiched between a layer
of Tungsten Carbide and Cobalt on one side and another layer made
of a material selected from the group comprising Tungsten Carbide,
or any other carbide of a refractory metal selected from the groups
IVB, VB, and VIB of the periodic table, and any combination
thereof. It should be noted that groups IVB, VB and VIB of the
periodic table referred to herein are the CAS version groups which
correspond to groups IVA, VA and VIA, respectively in the IUPAC
form of the periodic table.
[0019] In another exemplary embodiment, the CBN layer is sandwiched
between two layers each made from a material selected from the
group comprising carbides of refractory metals from the groups IVB,
VB, and VIB of the periodic table, and any combination thereof. In
a further exemplary embodiment, the flat cutting element comprises
a layer of CBN sandwiched between a layer made from a material
selected from the group of carbides of refractory metals from the
groups IVB, VB, and VIB of the periodic table, and any combination
thereof, and a layer of a refractory metal from the groups IVB, VB,
and VIB of the periodic table, as for example a layer of Tungsten,
Niobium, Tantalum or Molybdenum. In yet a further exemplary
embodiment, the flat cutting element comprises a layer of CBN
sandwiched between two layers each comprising a refractory metal
selected from the groups IVB, VB and VIB of the periodic table. In
another exemplary embodiment, the flat cutting element comprises a
layer of CBN sandwiched between two layers each made from a
material brazeable to carbide or steel.
[0020] The thickness ratio A:B (FIG.1) of a carbide layer to the
CBN layer of a flat composite cutting elements of the present
invention is in the range of about 9:1 to 36:1. The thickness ratio
A:B of a refractory metal layer to the CBN layer of a flat
composite cutting element of the present invention is in the range
of 0.3:1 to 2.25:1.
[0021] Applicants discovered that they can produce a flat composite
cutting element having a CBN layer sandwiched between two layers of
Tungsten Carbide without cracking of the Tungsten Carbide layers or
delamination of the Tungsten Carbide layers from the CBN layer, by
forming the CBN layer with a volume content percentage of CBN that
is less than 80%. By using a CBN layer formed with a volume content
of CBN that is less than 80%, the modulus mismatch between the CBN
layer and Tungsten Carbide layers is reduced thereby reducing the
risk of cracking or delamination of the Tungsten Carbide layers.
While reducing the volume percent content of the CBN reduces the
hardness of the CBN layer, the reduction in the CBN content
enhances the chemical stability of the CBN layer. In fact,
applicants discovered that by being able to use a CBN layer having
a volume percentage content of CBN of less than 80%, applicants
were able to tailor the CBN layer to have chemical and thermal
stability when the cutting element is used to cut different
materials. Exemplary grades of CBN include applicant Megadiamond's
MN-50 grade whose feed composition is depicted in FIG. 8. A feed
composition is the composition a material prior to sintering. It is
envisioned that the CBN layer may have a volume percentage of CBN
that may be 40% or less. It should be notes that all volume
percentages unless otherwise specified are volume percentages after
sintering.
[0022] The CBN layer compositions used in the cutting elements of
the present invention may include second phase materials such as
TiN, TiC, TiCN ranging from 0-45 volume percent and which have a
C:N ratio less than or equal to 1. In addition 10-15 volume percent
of the CBN layer composition may be a solution of AlN, AlB2 or
Co-Wc. Moreover, the CBN layer compositions may include a binder
phase in the range of 5% to 20% by volume.
[0023] Applicants have also discovered that the risk of cracking
and delamination to a Tungsten Carbide layer adjacent to CBN layer
is decreased by using a refractory metal layer on the other side of
the CBN layer, e.g., by sandwiching the CBN layer between the
Tungsten Carbide layer and a refractory metal layer selected from
the groups IVB, VB, and VIB of the periodic table, as for example,
Tungsten, Niobium, Tantalum and Molybdenum. Applicants have
discovered the residual stress distribution generated at the
interface between the carbide layer and the CBN layer when the
third layer is a refractory metal layer is not as conducive to the
initiation of cracks when compared to the stress distribution
generated at the interface between the Tungsten Carbide layer and
the CBN layer when the third layer is also a carbide layer.
[0024] Because there are modulus and coefficient of thermal
expansion mismatches between CBN and Tungsten Carbide, in any of
the above references exemplary embodiments, a cobalt solution is
infiltrated into the CBN composition which reduces the modulus
mismatch between the resulting CBN composition and the Tungsten
Carbide layer. This may be accomplished by using cobalt as the
binder in forming the Tungsten Carbide layer. As a result the
residual stresses generated at the interface between the CBN and
Tungsten Carbide are reduced.
[0025] Another way to reduce the magnitude of the residual stresses
generated at the interface between the central CBN layer and any of
the adjacent layers is to make the interface between the CBN layer
and its adjacent layer non-planar. An exemplary embodiment cutting
element 10 of the present invention having non-planar interface 40
between the CBN layer 16 and a first outer layer 18, and having
non-planar interface 42 between the CBN layer 16 and a second outer
layer 20 is shown in cross-section in FIG. 9. The geometries of the
interface may vary and may be formed with any of well known
methods.
[0026] One way to form the cutting element compact is to use a can
or cup which is made from a refractory metal selected from the
groups IVB, VB and VIB of the periodic table, as for example,
Tungsten, Niobium, Tantalum or Molybdenum. A typical can or cup 22
is shown in FIG. 3. A tungsten metal disk 24 is placed on the
bottom 26 of the can. CBN powder with a binder and other
appropriate constituents as for example set forth in FIG. 8, are
then placed over the disk for forming a CBN layer 16. A preferred
binder is AlN. The CBN layer 16 is covered by a layer 25,
comprising Tungsten Carbide powder and a binder such as Cobalt. The
Cobalt may be applied as a separate layer, as for example, a disc.
The can is covered with a cover 30 and the entire assembly is then
sintered under high pressure and temperature for forming a flat
cutting element compact having a CBN layer sandwiched between a
Tungsten layer and a Tungsten Carbide layer.
[0027] In an alternate exemplary embodiment shown in FIG. 4, the
can itself is used to form one layer of the cutting element
compact. For example, a Niobium can 22 may used to form a Niobium
layer. With this embodiment, at least one disk of Niobium 34 is
placed in the can over which is placed the CBN powder with
appropriate constituents and binder for forming the CBN layer 16. A
Tungsten Carbide powder with binder is then placed over the CBN
layer for forming the carbide layer 25. The can is then covered
with a cover 30 and the entire assembly is then sintered under high
pressure and temperature whereby the Niobium can bottom 26 and
Niobium disk 34 form a refractory metal layer of the cutting
element.
[0028] In a further alternate embodiment shown in FIG. 5, the CBN
powder with appropriate constituents and binder is placed directly
on the refractory metal can bottom 24 for forming the CBN layer 16.
The CBN powder is covered with Tungsten Carbide powder with binder
for forming the carbide layer 25. The assembly is then covered with
cover 30 and sintered. The sintered assembly is cut to remove
portions of the sintered can such that the can bottom 26 forms a
refractory metal, i.e., in this example a Niobium layer, which
sandwiches the CBN layer 16 with a Tungsten Carbide layer.
Alternatively, the carbide powder and binder is placed on the can
bottom followed by the CBN powder and constituents. The can in the
covered and sintered under high temperature and pressure. With this
latter embodiment, the cover of the can forms a refractory material
layer of the cutting element.
[0029] In yet a further exemplary embodiment shown in FIG. 6, CBN
powder with appropriate constituents and binder for forming a CBN
layer 16 is placed in the refractory metal can 22 and sintered.
With this embodiment, portions of the can, as for example the can
bottom and cover are used to form the two refractory metal layers
sandwiching the CBN layer.
[0030] To form a cutting element of the present invention
comprising a layer 16 of CBN sandwiched between two carbide layers,
Tungsten Carbide powder and a Cobalt binder or a Tungsten Carbide
disk and a Cobalt binder or Tungsten Carbide Cobalt disk is placed
on the refractory metal can bottom 26 (FIG. 7). CBN powder with
constituents and binder placed over the carbide powder. The CBN
powder is then covered by Tungsten Carbide powder and binder. The
assembly is then covered with cover 32 and sintered. Furthermore,
with any of the aforementioned embodiments, instead of powder form,
the CBN layer 16 may be in sheet form which may be preformed with
the inclusion of a binder. If a carbide layer comprising a carbide
of a refractory metal from the groups IVB, VB, and VIB of the
periodic table or any combination thereof is desired then such
carbide material may be substituted for forming the layer 25. The
carbide layers may also be preformed in sheet form.
[0031] With any of the aforementioned embodiments, the sintered can
assembly is cut to expose the cutting element.
[0032] Although the present invention has been described and
illustrated to respect multiple embodiments thereof, it is to be
understood that it is not to be so limited, since changes and
modifications may be made therein which are within the full
intended scope of this invention as hereinafter claimed.
* * * * *