U.S. patent application number 10/558239 was filed with the patent office on 2007-08-02 for method of making a tool component.
Invention is credited to Robert Fries, Iakovos Sigalas.
Application Number | 20070175103 10/558239 |
Document ID | / |
Family ID | 33477334 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070175103 |
Kind Code |
A1 |
Sigalas; Iakovos ; et
al. |
August 2, 2007 |
Method of making a tool component
Abstract
A method of producing a tool component comprising a working
portion of bonded abrasive particles including a non-homogeneous
region. The method includes the step of providing at least two
sources of a material comprising abrasive particles in a suitable
binder, the materials of the sources differing from each other. The
material of one source may comprise diamond or cubic boron nitride
particles, whilst the material of the other source may comprise
carbide particles. Alternatively, the materials of the two sources
may contain the same abrasive particle, such as diamond or cubic
boron nitride particles, but in different particle sizes. The
materials are delivered to a zone where mixing occurs, and the
mixture is applied to a surface to produce a layer of the mixed
materials on the surface, typically by spraying. By controlling the
quantity of material from each source which is delivered to the
mixing zone, different mixtures of the two abrasives can be
created. In this way, layers, e.g. one on top of the other, can be
produced which differ from their neighbours in abrasive particle
composition. These layers, on sintering, form non-homogeneous
regions in the working portion of a tool component.
Inventors: |
Sigalas; Iakovos; (Linden,
ZA) ; Fries; Robert; (Saxonwold, ZA) |
Correspondence
Address: |
SCULLY SCOTT MURPHY & PRESSER, PC
400 GARDEN CITY PLAZA
SUITE 300
GARDEN CITY
NY
11530
US
|
Family ID: |
33477334 |
Appl. No.: |
10/558239 |
Filed: |
May 20, 2004 |
PCT Filed: |
May 20, 2004 |
PCT NO: |
PCT/IB04/01630 |
371 Date: |
January 2, 2007 |
Current U.S.
Class: |
51/298 ; 51/307;
51/308; 51/309 |
Current CPC
Class: |
C04B 2235/405 20130101;
C04B 2235/5436 20130101; C23C 4/185 20130101; C23C 24/08 20130101;
C04B 2235/3847 20130101; C04B 2235/6582 20130101; C04B 35/5626
20130101; C04B 2235/75 20130101; B22F 7/02 20130101; C23C 30/005
20130101; C04B 2235/427 20130101; C04B 35/52 20130101; B24D 18/00
20130101; C23C 24/00 20130101; B24D 3/10 20130101 |
Class at
Publication: |
051/298 ;
051/307; 051/308; 051/309 |
International
Class: |
B24D 3/02 20060101
B24D003/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 22, 2003 |
ZA |
2003/3969 |
Claims
1. A method of producing a tool component comprising a working
portion of bonded abrasive particles, which includes a
non-homogeneous region, the method including the steps of providing
at least two sources of a material comprising abrasive particles in
a suitable binder, the materials of the sources differing from each
other, delivering a quantity of the materials to a zone where
mixing occurs and applying the mixed materials to a surface to
produce a layer of the mixed materials on the surface.
2. A method according to claim 1, wherein the layer of mixed
materials forms at least a part of the non-homogeneous region of
the working portion of the tool component.
3. A method according to claim 1, wherein the non-homogeneous
region differs in size of abrasive particle, in the nature of the
abrasive particle or in a combination thereof.
4. A method according to claim 1, wherein the layer of the mixed
materials is a green state form of the non-homogeneous region.
5. A method according to claim 1, comprising first and second
sources of material, the first source comprising a mass of discrete
ultra-hard abrasive particles in a binder and the second source
comprising a mass of discrete abrasive particles, different to
those of the material of the first source, in a binder.
6. A method according to claim 5, wherein the first source of
material comprises a mass of discrete diamond or cubic boron
nitride particles in a binder and the second source of material
comprises carbide particles in a binder.
7. A method according to claim 1, comprising first and second
sources of material, the materials of the two sources containing
the same abrasive particle, but in different particle sizes.
8. A method according to claim 1, wherein the mixed materials are
delivered from the mixing zone in the form of a spray.
9. A method according to claim 1, wherein the surface to which the
layer or layers of mixed material is applied is the surface of a
cemented carbide substrate producing a green state composite
abrasive compact.
10. A method according to claim 1, wherein the surface to which the
layer or layers of mixed materials is applied is the surface of a
substrate which is sacrificed leaving a green state layer or layers
of mixed materials which may be sintered.
11-12. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a method of making a tool
component.
[0002] Abrasive compacts are used extensively in cutting, milling,
grinding, drilling, boring and other abrasive operations. Abrasive
compacts consist of a mass of diamond or cubic boron nitride
particles bonded into a coherent, polycrystalline conglomerate. The
abrasive particle content of abrasive compacts is high and there is
generally an extensive amount of direct particle-to-particle
bonding. Abrasive compacts are made under elevated temperature and
pressure conditions at which the abrasive particle, be it diamond
or cubic boron nitride, is crystallographically stable.
[0003] Diamond abrasive compacts are also known as polycrystalline
diamond or PCD and cubic boron nitride abrasive compacts are also
known as polycrystalline CBN or PCBN.
[0004] Abrasive compacts tend to be brittle and in use they are
frequently supported by being bonded to a cemented carbide
substrate or support. Such supported abrasive compacts are known in
the art as composite abrasive compacts. Composite abrasive compacts
may be used as such in a working surface of an abrasive tool. Where
the composite abrasive compact has a thick abrasive compact layer,
particularly a thick diamond compact layer, residual tensile
stresses in the abrasive compact layer develop giving rise to
problems in use. These stresses contribute to delamination and
fracture of the compact layer in use. To minimise these problems,
the interface between the abrasive compact layer and carbide
substrate may be profiled and/or the composition of the compact
layer varied, for example by introducing some carbide particle
content in a region or regions adjacent the substrate/compact layer
interface.
[0005] Cemented carbide is used as a material for producing tool
components which have an abrasiveness and hardness less than PCD or
PCBN. Such tool components may consist of a homogeneous cemented
carbide or a cemented carbide which varies in composition.
SUMMARY OF THE INVENTION
[0006] According to the present invention, a method of producing a
tool component which comprises a working portion of bonded abrasive
particles and which includes a non-homogeneous region includes the
steps of providing at least two sources of a material comprising
abrasive particles in a suitable binder, the materials of the
sources differing from each other, delivering a quantity of the
materials to a zone where mixing occurs and applying the mixed
materials to a surface to produce a layer of the mixed materials on
the surface. The layer of mixed materials will form at least a part
of the non-homogeneous region of the working portion of the tool
component. The non-homogeneous region can differ in size of
abrasive particle, in the nature of the abrasive particle or in a
combination thereof. The layer of the mixed materials is a green
state form of the non-homogeneous region.
[0007] In one form of the invention, the material of one source
comprises a mass of discrete ultra-hard abrasive particles such as
diamond or cubic boron nitride in a binder. The material of the
other source comprises a mass of discrete abrasive particles
different to those of the material of the first source, for example
carbide particles, in a binder. By controlling the quantity of
material from each source which is delivered to the mixing zone,
different mixtures of the two abrasives can be created. In this
way, layers, e.g. one on top of the other, can be produced which
differ from their neighbours in abrasive particle composition.
These layers, on sintering, form non-homogeneous regions in the
working portion of a tool component.
[0008] In another form of the invention, the materials of the two
sources contain the same abrasive particle, but in different
particle sizes. In a similar manner by controlling the quantity of
material from each source which is. delivered to the mixing zone,
layers which differ in particle size composition from each other
can be produced.
[0009] It is preferred that the mixed materials are delivered from
the mixing zone in the form of a spray.
[0010] The surface to which the layer or layers of mixed material
is applied may be the surface of a cemented carbide substrate
producing, for example, a green state composite abrasive compact.
This green state composite abrasive compact, on sintering at
temperature and pressure conditions at which the abrasive particle
is crystallographically stable, results in a composite abrasive
compact being produced. The surface to which the layer of mixed
materials is applied may be the surface of a substrate which is
sacrificed leaving a green state layer or layers of mixed materials
which may be sintered.
BRIEF DESCRIPTION OF THE DRAWING
[0011] The invention will now be described in more detail, by way
of example only, with reference to the accompanying drawing which
is a diagrammatical representation of apparatus suitable for
carrying out an embodiment of the invention.
DESCRIPTION OF EMBODIMENTS
[0012] Embodiments of the invention will now be described with
reference to the accompanying drawing. Referring to the drawing,
there is shown apparatus comprising containers 10, 12. The
containers are suitable for holding a mass of abrasive particles in
a suitable binder. Examples of suitable binders are organic binders
such as methyl or ethyl cellulose or polyvinylpyrrolidone. The
abrasive particles will generally be uniformly dispersed in the
binder and will be flowable. The abrasive particles of container 10
will, for example, be ultra-hard abrasive particles such as diamond
or cubic boron nitride. The abrasive particles of container 12 will
be different to those of container 10 and will, for example, be
carbide particles. Passage 14 from container 10 leads to a mixing
zone 16. Flow of material from the container 10 is controlled from
valve 18. Passage 20 from container 12 leads to the mixing zone 16.
Flow of material from container 12 is controlled by valve 22.
[0013] In use, a substrate 24, typically a cemented carbide
substrate, is provided. The substrate is cylindrical in shape and
has an upper flat surface 26 and a lower flat surface 28. A first
layer 30 of mixed materials is applied to the surface 26. This is
achieved by opening valves 18, 22 to a desired extent, thereby
delivering material from each of the containers 10, 12 to the
mixing zone 16. The materials are thoroughly mixed in zone 16 and
thereafter sprayed through nozzle 32 on to the surface 26.
Thereafter, a second layer 34 is applied to the layer 30. This
layer will also be applied using this wet powder spraying (WPS)
method, save that the proportions of material delivered from
containers 10 and 12 will be varied by means of the amount
delivered through the valves 18, 22. Additional layers are added to
the layer 34. The compositions of these additional layers will be
tailored to meet specific requirements.
[0014] The layered product is a green state product. The layers on
the substrate 34 are all coherent and hold their shape. The green
state product is then sintered to cause the various layers to
sinter and bond to each other and the layer 30 to bond to the
substrate. For example, the container 10 may contain diamond
particles, in which event the container will generally contain
finely particulate metal such as nickel, iron or cobalt as a
mixture with the diamond particles. The container 12 may contain
carbide particles. The layers 30 and 34 will generally contain a
mixture of diamond particles and carbide particles in varying
amounts. The outer layer or layers will generally contain only
diamond particles. The green state product will be sintered under
diamond synthesis conditions and the resulting product will be a
composite diamond abrasive compact. A diamond compact layer will be
formed from the green state layers. The diamond compact layer of
such a product will be substantially stress-free.
[0015] In an alternative embodiment of the invention, the container
10 may contain abrasive particles of a particular size and the
container 12 contain the same abrasive particles but of different
size. The various layers in the green state product may thus all
contain the same abrasive particles but the size composition of
each layer may be varied to achieve a particular objective.
[0016] It will be appreciated that by use of the method of the
invention, it is possible to produce layered structures having a
wide range of compositions varying from each other. Further, the
illustrated embodiment has the layers one on top of the other. The
method can also be used to produce layers which are vertically or
otherwise disposed relative to each other.
[0017] The layered structure may be applied directly to a substrate
to which it is desired to bond the layers on sintering.
Alternatively, the layers may be applied to a surface, then removed
from that surface and applied to a surface of a substrate to which
bonding takes place.
[0018] The method of the invention may be further understood with
reference to the following non-limiting Examples.
EXAMPLE 1
[0019] A cylindrical-shaped component was prepared with a
WC/diamond gradient in the axial direction using the wet powder
spraying (WPS) method of the invention. The starting layer of the
cylinder was a 4 mm layer of WC/Co. This was not prepared using the
wet powder spraying method, but was rather pressed from
commercially available powder at 100 MPa to obtain a strong, porous
support for the subsequent layer deposition. This base layer was
then strengthened further by a pre-sintering treatment under
hydrogen at 600.degree. C. The porosity of this layer was chosen to
achieve a similar shrinkage behaviour to the overlying layers. The
WC/Co grain composition was the same as that used in the diamond
graded layers.
[0020] 49 gradient layers, each of approximately 100 .mu.m
thickness, with WC/diamond ratios varying in a monotonic manner
were then deposited onto the WC/Co base by the WPS method. The
diamond and WC particles were provided from separate containers,
each in a suspension which included polyvinylpyrrolidone as binder,
Lupasol P as dispersant and water. The composition ranged from 98%
WC/2% diamond (by mass) in the layer immediately adjacent to the
base layer to 100% diamond in the uppermost layer. The composition
was altered in 2% steps by altering the flow of WC particles from
one container and diamond particles from another container. In
order to preserve a cylindrical shape in the component, a
cylindrical mold was used for containing the sprayed layers.
[0021] As the concentration of diamond particles, which had an
average particle size of about 4 .mu.m, in the suspension increased
(according to the axial gradient), so the overall composition of
the suspension altered. The decrease in matrix mass due to the
density difference between diamond and WC/Co meant that the binder
and dispersant masses had to decrease in a similar fashion. The
overall water content therefore increased with respect to the dry
powder weight. Each layer was dried before the subsequent layer was
sprayed to prevent shrinkage problems.
[0022] The green compact was then de-binded at a sufficiently high
temperature to remove the binder and dispersant phases. A high
pressure, high temperature treatment was then used to sinter the
green compact to produce a sintered compact. The sintered compact
exhibited a marked reduction in residual tensile stresses in the
abrasive compact layer.
EXAMPLE 2
[0023] A cylindrical-shaped component was prepared with a diamond
grain size gradient in the axial direction using a wet powder
spraying (WPS) method similar to that described in Example 1. The
diamond layer immediately adjacent to the WC/Co base layer was
chosen to have an average grain size of approximately 25 .mu.m,
whilst the diamond layer in the uppermost layer was chosen to have
an average grain size of approximately 4 .mu.m. 50 layers were
deposited, each of approximately 100 .mu.m in thickness. The ratio
of the two diamond grain sizes was altered in monotonic manner in
2% compositional intervals, from 100% 25 .mu.m diamond at the base
surface to 100% 4 .mu.m diamond at the uppermost surface.
[0024] The mass composition of the WPS suspension did not alter
signficantly from the base to the top layers, as the matrix
material was consistently diamond throughout. The final compact was
de-binded in a similar fashion to the compact generated in Example
1, and was then treated under high pressure and high temperature to
achieve a fully sintered compact with diamond to diamond bonding.
The sintered compact once again provided an abrasive compact layer
with a significant reduction in residual tensile stresses.
EXAMPLE 3
[0025] A cylindrical-shaped component was prepared with a gradient
in diamond grain size and chemical composition in the axial
direction using a wet powder spraying (WPS) method similar to that
described in Example 1.
[0026] The layer immediately adjacent to the WC/Co base layer
contained diamond grains of 25 .mu.m in size and WC/Co particles of
2.5 .mu.m in size in a 75:25 (diamond:WC/Co) mass ratio. The
uppermost layer contained 100% diamond material of an average of 4
.mu.m in size. The ratio of these two source compositions was
altered in monotonic manner in 2% compositional intervals, from
100% (25 .mu.m diamond/(WC/Co) mix) at the base surface to 100% 4
.mu.m diamond at the uppermost surface.
[0027] The final compact was then de-binded in a similar fashion to
the compact generated in Example 1, and was then treated under high
pressure and high temperature to achieve a fully sintered compact
with diamond to diamond bonding. Residual tensile stresses were
once again significantly reduced in the abrasive compact layer.
* * * * *