Information
-
Patent Grant
-
6733378
-
Patent Number
6,733,378
-
Date Filed
Thursday, February 1, 200123 years ago
-
Date Issued
Tuesday, May 11, 200420 years ago
-
Inventors
-
-
Examiners
- Hail, III; Joseph J.
- Grant; Alvin J
Agents
- Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
-
CPC
-
US Classifications
Field of Search
US
- 451 530
- 451 539
- 451 548
- 451 540
- 451 541
- 175 428
-
International Classifications
-
Abstract
An abrasive body which includes an abrasive layer bonded to a substrate along an interface and at least one strip-like projection extending from the interface into the substrate. The projection has a profile which includes a substantially flat central portion and connecting surfaces to either side of the central section. The surface is sloped from the central section to the interface.
Description
BACKGROUND OF THE INVENTION
This invention relates to an abrasive body and more particularly to an abrasive body which can be used as a tool insert.
Composite abrasive compacts are products used extensively as inserts for abrasive tools such as drill bits. Such composite abrasive compacts comprise an abrasive compact layer bonded to a cemented carbide support. The abrasive compact will typically be a diamond abrasive compact, also known as polycrystalline diamond or PCD, or a cubic boron nitride compact, also known as polycrystalline CBN or PCBN.
Composite abrasive compacts are manufactured under elevated temperature and pressure conditions. e.g. diamond or cubic boron nitride synthesis conditions.
As it is known that PCD composite compacts contain considerable residual stresses as a result of the high temperature/high pressure conditions used in their manufacture. Further, methods of mounting such compacts into drill bits, for example press fitting or brazing, can modify the stress distributions in the compacts. Additional stresses are imposed on the compacts during their use in applications such as drilling. Stresses may be introduced into the interface between the abrasive compact layer and the cemented carbide support. These stresses may be reduced or modified by providing a recess which extends into the cemented carbide support from the compact/carbide interface and which is filled with the abrasive compact. In the prior art, the recess has taken various shapes such as a plurality of concentric rings, a V-shaped recess, a cross-shaped recess, and a recess which incorporates a number of steps. A purpose in most of such designs is to reinforce and support the cutting edge by providing overall rigidity for the composite compacts.
U.S. Pat. No. 5,472,376 describes a tool component comprising an abrasive compact layer bonded to a cemented carbide substrate along an interface. A recess extends from the interface into the substrate and is filled with abrasive compact. The recess has a stepped configuration and is located entirely within the carbide substrate.
EP 356097 describes a tool insert comprising an abrasive compact bonded to a cemented carbide substrate. The abrasive compact is located in a recess formed in the substrate. The abrasive compact has a top surface which provides a cutting edge for the tool insert, a bottom surface complimentary to the base of the recess and a side surface at least partially located in the recess, the portion of the side surface located in the recess being complimentary to the side of the recess. The side surfaces may be sloping.
SUMMARY OF THE INVENTION
According to the present invention, an abrasive body, for use, for example, as a tool insert, comprises an abrasive layer bonded to a substrate along an interface and at least one strip-like abrasive projection extending from the interface into the substrate, the projection having a profile which includes a substantially flat central portion and surfaces to either side thereof which slope towards the interface.
More than one strip-like projection may be provided. Such projection or projections may extend from one peripheral surface of the abrasive body to an opposite peripheral surface. The projection or projections preferably have a surface coincident with a peripheral surface of the body.
In another form of the invention, three parallel strip-like projections are provided, the inner projection having a width greater than that of the outer projections.
In yet another form of the invention, the strip-like projection has an essentially U-form in plan. Preferably, the limbs of the U have ends coincident with an outer surface of the body.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a plan view of a first embodiment of the invention,
FIG. 2
is a section along the line
2
—
2
of
FIG. 1
,
FIG. 3
is a section along the line
3
—
3
of
FIG. 1
,
FIG. 4
is a plan view of a further embodiment of the invention,
FIG. 5
is a section along the line
5
—
5
of
FIG. 4
,
FIG. 6
is a section along the line
6
—
6
of
FIG. 4
, and
FIG. 7
is a sectional side view of a further embodiment of the invention.
DESCRIPTION OF EMBODIMENTS
The abrasive body may have various shapes, but is preferably right circular cylindrical.
The substrate layer will typically be a cemented carbide substrate layer. The cemented carbide of the substrate may be any known in the art such as cemented titanium carbide, cemented tungsten carbide, cemented tantalum carbide, cemented molybdenum carbide, or mixtures thereof. As is known, such cemented carbides will typically have a binder content of 3 to 30% by mass. The metal binder will typically be cobalt, iron or nickel or an alloy containing one or more of these metals.
The abrasive layer will generally be an abrasive compact layer or a layer of diamond produced by chemical vapour deposition (CVD). When the abrasive layer is an abrasive compact layer, it will preferably be a diamond compact layer or a cubic boron nitride compact layer.
A first embodiment of the invention will now be described with reference to
FIGS. 1
to
3
. Referring to these figures, there is shown an abrasive body comprising an abrasive compact layer
10
bonded to a substrate
12
, generally a cemented carbide substrate, along an interface
14
(see FIG.
2
). The top surface
16
of the layer
10
provides an abrasive surface for the body and the peripheral edge
18
provides a cutting edge, remote from the interface. The interface
14
has portions
14
a
and
14
b
which slope relative to the surface
16
and central portions
14
c
and
14
d
which are parallel to this surface. All these portions of the interface
14
may, in an alternative embodiment, be parallel to the surface
16
.
The abrasive body is characterised, in particular, by the provision of three strip-like projections
20
of abrasive compact which extend from the interface
14
into the substrate
12
. These projections
20
extend from one peripheral side surface of the abrasive body to an opposite peripheral side surface. Thus, each projection has a surface identified as
22
and
24
coincident with a peripheral side surface of the abrasive body.
The profile i.e. the longitudinal cross-sectional shape, of the strips is best illustrated by FIG.
3
. Referring to this figure, it will not noted that the profile is such that there is a central flat section identified as
26
and surfaces
28
,
30
to either side of the central section. The surfaces
28
,
30
slope from the central section
26
to the interface
14
.
It will be noted from
FIGS. 1 and 2
that the width in plan of the central strip-like projection is greater than that of the outer strip-like projections. This is a preferred configuration. Other configurations, e.g. in which the widths are the same, are possible.
A second embodiment of the invention will now be described with reference to
FIGS. 4
to
6
. Referring to these figures, an abrasive body comprises an abrasive compact
100
bonded to a substrate
102
, particularly a cemented carbide substrate, along an interface
104
. The surface
106
of the abrasive compact layer
100
provides an abrasive surface for the body, while the peripheral edge
108
provides a cutting edge, remote from the interface.
An abrasive compact projection
110
extends from the interface
104
into the substrate
102
. This projection has an essentially U-shape in plan, as can be seen from FIG.
5
. The limbs of the U extend to the outer surface
112
of the abrasive body. Thus, the limbs have edge surfaces
114
coincident with the outer surface
112
of the body.
The profile of the projection
110
is illustrated from different directions by
FIGS. 5 and 6
. It will be noted from these figures that the profile is such that there is a central flat section
116
and surfaces
118
which slope from the central section
116
to the interface
104
.
The abrasive bodies described above may be made by methods known in the art. Generally this will involve providing a cylindrical shaped cemented carbide body having a recess, to receive the components necessary to make an abrasive compact, formed in one end thereof. An example of such a body, to produce an abrasive body of
FIGS. 1
to
3
, is shown in FIG.
7
. Referring to this figure, a cemented carbide body
60
is of right-circular cylindrical shape having flat ends
62
and
64
. A recess
66
is provided in the end
62
. This recess is filled with the components necessary to make an abrasive compact. The thus produced unbonded assembly is placed in the reaction zone of a conventional high temperature/high pressure apparatus to form an abrasive compact of the components which bonds to the body
60
. The abrasive body illustrated by
FIGS. 1
to
3
is produced by simply removing the sides of the body
60
, as illustrated by the dotted lines. However, the bonded body which is recovered from the reaction zone after compact formation and without removal of the carbide sides, may be used as a tool insert itself, and forms another aspect of the invention. In this form of the insert, the edge
70
will provide the cutting edge. This edge is likely to wear away fairly rapidly until the abrasive compact edge
72
is reached. Thereafter it is this edge
72
which provides the cutting edge for the component.
The provision of the strip-like projections in the abrasive bodies of the invention result in an effective reinforcement and support for the cutting edge by providing overall rigidity for the bodies. Further, in use the cutting edges in the regions of the surfaces
22
,
24
of the projection for the
FIGS. 1
to
3
embodiment and in the region of the surfaces
114
of the projection for the
FIGS. 4
to
6
embodiment will be employed. The extra abrasive available in these regions increases effectiveness of the abrasive action of the body.
Claims
- 1. An abrasive body comprises an abrasive layer bonded to a substrate along an interface and at least three parallel strip-like projections extending from the interface into the substrate, the projections each having a profile which includes a substantially flat central portion and connecting surfaces which join the flat central portion to the interface and slope towards the interface, wherein an inner projection is provided with a width greater than that of outer projections.
- 2. An abrasive body according to claim 1 wherein the strip-like projections extend from one peripheral surface of the abrasive body to an opposite peripheral surface.
- 3. An abrasive body according to claim 1 wherein the projections have a surface coincident with a peripheral surface of the body.
- 4. An abrasive body according to claim 1 wherein the abrasive layer is selected from an abrasive compact and a layer of diamond produced by chemical vapour deposition.
- 5. An abrasive body according to claim 1 wherein the substrate is a cemented carbide substrate.
- 6. An abrasive body according to claim 1 which has a right-circular cylindrical shape.
- 7. An abrasive body according to claim 1, wherein the abrasive layer has a cutting edge, and wherein the projections are oriented substantially perpendicular to the cutting edge.
- 8. An abrasive body comprises an abrasive layer bonded to a substrate along an interface and a plurality of strip-like projections extending from the interface into the substrate, the abrasive layer having a planar top surface, the projections each having a profile which includes a substantially flat central portion and connecting surfaces which join the flat central portion to the interface and slope from the central portion towards the top surface, wherein the strip-like projections are substantially U-shaped in plan view.
- 9. An abrasive body according to claim 8 wherein limbs of the U have ends coincident with an outer surface of the body.
- 10. An abrasive body comprises an abrasive layer bonded to a substrate along an interface and at least one strip-like projection extending from the interface into the substrate, the abrasive layer having a planar top surface, the projection having a widthwise profile which includes a substantially flat central portion and first connecting surfaces which join the central portion to the interface and extend from the central portion towards the top surface, and the projection having a lengthwise profile which includes the substantially flat central portion and second connecting surfaces which join the central portion to the interface and incline from the central portion towards the top surface.
- 11. A method of using an abrasive body including an abrasive layer bonded to a substrate along an interface and at least one strip-like projection extending from the interface into the substrate, the projection having a profile which includes a substantially flat central portion and connecting surfaces which join the flat central portion to the interface and slope towards the interface, the abrasive layer having a cutting edge wherein the at least one strip-like projection is oriented substantially perpendicular to the cutting edge, the method comprising the step of:mounting the abrasive body as an insert for an abrasive tool wherein the cutting edge is oriented to cut an object being worked on by the abrasive tool.
Priority Claims (1)
Number |
Date |
Country |
Kind |
98/5923 |
Jul 1998 |
ZA |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/IB99/01230 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO00/01917 |
1/13/2000 |
WO |
A |
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
5472376 |
Olmstead et al. |
Dec 1995 |
A |
5645617 |
Frushour |
Jul 1997 |
A |
Foreign Referenced Citations (4)
Number |
Date |
Country |
0 356 097 |
Feb 1990 |
EP |
0 659 510 |
Jun 1995 |
EP |
0 692 607 |
Jan 1996 |
EP |
0 692607 |
Mar 1996 |
EP |