U.S. patent application number 10/554630 was filed with the patent office on 2007-03-08 for high-speed machining tool.
This patent application is currently assigned to Tatsuhiko AIZAWA. Invention is credited to Tatsuhiko Aizawa, Atsushi Mitsuo.
Application Number | 20070054146 10/554630 |
Document ID | / |
Family ID | 33410126 |
Filed Date | 2007-03-08 |
United States Patent
Application |
20070054146 |
Kind Code |
A1 |
Aizawa; Tatsuhiko ; et
al. |
March 8, 2007 |
HIGH-SPEED MACHINING TOOL
Abstract
Object: A high speed machining component, which has been
improved in wear resistance and lubricating properties, and a high
speed dry machining method using the component are provided.
Particularly, a high speed cutting tool and a high speed cutting
method are provided. Means for solution: A halogen element is
ion-implanted into a machining component having a cemented carbide
as a base material, and the machining component is contacted with a
workpiece at a speed of 150 m/min or higher, whereby the wear
resistance and lubricating properties of the component can be
improved. If the machining component has a Ti-containing coating
layer, its wear resistance and lubricating properties can be
improved similarly. The use of a cutting tool including such a
component enables high speed dry cutting without a cutting oil. By
bringing the machining component of the present invention into
contact with the workpiece at a high speed, a self-lubricating film
can be formed on a surface of contact of the component with the
work material.
Inventors: |
Aizawa; Tatsuhiko;
(Komae-shi, JP) ; Mitsuo; Atsushi; (Kita-ku,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Tatsuhiko AIZAWA
2-5-5, Iwadokita, Komae-shi
Tokyo
JP
201-0004
|
Family ID: |
33410126 |
Appl. No.: |
10/554630 |
Filed: |
April 28, 2004 |
PCT Filed: |
April 28, 2004 |
PCT NO: |
PCT/JP04/06142 |
371 Date: |
November 2, 2006 |
Current U.S.
Class: |
428/544 |
Current CPC
Class: |
B23B 27/14 20130101;
Y10T 428/12 20150115; C23C 14/48 20130101; B23B 2228/10 20130101;
B23B 2224/32 20130101; B23B 27/10 20130101 |
Class at
Publication: |
428/544 |
International
Class: |
B22D 7/00 20060101
B22D007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2003 |
JP |
2003-123418 |
Claims
1. A high speed machining component having a hard material as a
base material, and containing at least one element selected from
the group consisting of fluorine, chlorine, bromine and iodine, a
concentration of the element being in a range of 0.2 mol % to 10
mol % within 1 .mu.m from a surface of the base material.
2. A high speed machining component having a hard material as a
base material, having a coating layer containing Ti and C and/or N
on an outside of the base material, and containing at least one
element selected from the group consisting of fluorine, chlorine,
bromine and iodine, a concentration of the element being in a range
of 0.2 mol % to 10 mol % within 1 .mu.m from a surface of the
coating layer.
3. The component according to claim 2, wherein the coating layer
contains one or more members selected from the group consisting of
TiC, TiN, TiCN and TiAlCN.
4. The component according to any one of claims 1 to 3, wherein the
at least one element selected from the group consisting of
fluorine, chlorine, bromine and iodine has been added by ion
implantation.
5. The component according to any one of claims 1 to 4, wherein a
concentration of Ti is in a range of 0.2 mol % to 80 mol % within 1
.mu.m from a surface of machining component.
6. The component according to any one of claims 1 to 5, wherein the
base material is a cemented carbide.
7. A high speed machining component produced by bringing the
component according to any one of claims 1 to 6 into contact with a
workpiece at a speed of 150 m/min or higher.
8. The component according to any one of claims 1 to 6, further
having a self-lubricating film is a film formed by bringing the
component into contact with the workpiece at a speed of 150 m/min
or higher.
9. The component according to claim 8, wherein the self-lubricating
film is a film formed by bringing the component into contact with
the workpiece at a speed of 150 m/min or higher.
10. The component according to claim 9, wherein the workpiece used
for formation of the self-lubricating film contains Ti in a surface
layer thereof.
11. The component according to any one of claims 8 to 10, wherein
the self-lubricating film contains a Ti oxide and/or a
Ti-containing compound oxide; an average valence of Ti in the oxide
and/or the compound oxide is greater than 2, but less than 4; and
if an amount of Ti in the self-lubricating film is calculated as
TiO.sub.2, a mass ratio expressed as (mass of the calculated
TiO.sub.2/mass of the self-lubricating film) is 5% or more.
12. A high speed machining method including a step of bringing the
component according to any one of claims 1 to 11 into contact with
an article at a relative speed of 150 m/min or higher to machine
the article.
13. A high speed cutting tool including the component according to
any one of claims 1 to 11.
14. The high speed cutting tool according to claim 13 or 14,
wherein a wear width V.sub.B of a tool flank after cutting is
performed under conditions including a depth of cut of 1.0 mm, a
feed rate of 0.1 mm/rev, a cutting speed of 400 m/min, and a
cutting length of 500 m is 70 .mu.m or less.
15. A cutting method including a step of cutting an article by the
cutting tool according to claim 13 or 14 at a cutting speed of 150
m/min or higher without use of a cutting oil.
16. A method for producing a high speed machining component,
including a step of bringing the component according to any one of
claims 1 to 6 into contact with a workpiece at a speed of 150 m/min
or higher.
Description
TECHNICAL FIELD
[0001] This invention relates to a component which is excellent in
wear resistance, lubricating properties, and fracture resistance,
and can be used for high speed machining applications. The
invention also relates to a machining tool including the component,
and a high speed machining method, especially, a dry cutting
method, using the tool.
BACKGROUND ART
[0002] In recent years, a high machining speed has been demanded
from the viewpoint of increased productivity, and high speed
cutting has been desired, for example, in the field of cutting. The
range of targets for high speed cutting has been expanded, and
there has been a demand for the application of high speed cutting
to high hardness materials such as hot forging dies after hardening
by heat treatment, and die casting molds.
[0003] With conventional cutting methods, cutting oils were used
for promoting a lubricating action and cooling a cutting edge, and
cutting oils were needed, particularly, in high speed cutting.
However, the use of a cutting oil may aggravate a work environment
because of a foreign odor, dirt, and greasy fumes. In addition,
treatment of a waste oil may pose the problem of environmental
pollution, and cause the corrosion of tools. Thus, dry cutting
using no cutting oil is desired and, for this purpose, there is
need for the development of a cutting tool having wear resistance,
fracture resistance, lubricating properties, and heat resistance.
Such a cutting tool should desirably have the above-mentioned
characteristics even in a high speed region.
[0004] As tools for dry cutting, there are reports on tools having
high hardness coatings formed on hard materials for improved
durability. Their examples include a high speed tool steel having a
Ti--Al--N--C-based coating (see Japanese Patent Application
Laid-Open No. 1999-300518), and cemented carbides having coating
layers comprising constituents such as TiCN, TiAlN, SiC and
Al.sub.2O.sub.3 (see Japanese Application Laid-Open No. 2000-336489
and Japanese Patent Application Laid-Open No. 2001-293611). Methods
such as CVD and PVD are used for the formation of these coating
layers. An attempt has also been made to perform ion implantation
of elements such as Cl and S into tungsten carbide for increased
wear resistance (see U.S. Pat. No. 5,038,645).
[0005] With the conventional methods of applying coatings to base
materials, however, a coating layer, which comprises a different
material from the base material, is deposited, so that peeling is
apt to occur between the coating layer and the base material. To
enhance adhesion, a method of forming a plurality of layers has
been attempted, but involves a complicated process. Furthermore,
even when a coating layer of high hardness is formed, its toughness
may be low and, depending on a material to be cut (namely, a work
material), fracture may occur, resulting in an insufficient tool
life. In addition, when the work material is cut with the high
hardness coating layer, swarf deposits on the coating layer, thus
presenting the problem that cutting resistance in a high speed
region is not fully decreased. With ion implantation of tungsten
carbide, wear resistance is improved in a medium speed region (for
example, a cutting speed of up to 91 m/minute), but performance
obtained is inferior to that of coated tools.
[0006] Because of the above-described problems, the cutting speed
of the current steels is often set at a maximum of 150 to 200 m/min
even with the use of a cutting oil, and is often set at 100 /min or
less in dry cutting. Thus, dry cutting in a high speed region is
difficult.
DISCLOSURE OF THE INVENTION
[0007] The present invention has been accomplished in light of the
above-described circumstances. It is an object of the invention to
provide a machining component, especially, a high speed cutting
tool, improved in wear resistance, fracture resistance, lubricating
properties, cutting resistance, and heat resistance in a high speed
region. It is another object of the invention to provide a high
speed machining method, especially a high speed dry cutting method,
using the machining component of the present invention.
[0008] The present inventors have diligently conducted studies, and
found that when a halogen element is added to a surface layer of a
machining component, and a workpiece is brought into contact with
the so treated machining component at a high speed,
characteristics, such as wear resistance and lubricating
properties, are improved in accordance with the oxidation promoting
effect of the halogen element. This finding has led to the
accomplishment of the present invention. According to the present
invention, the machining component and the workpiece are subjected
to friction at a high speed to cause an interface reaction, whereby
the surface of the machining tool according to the present
invention, because of its excellent lubricating properties, enables
high speed machining without using a lubricating oil.
[0009] The above advantages of the present invention are presumed
to be ascribed to a self-lubricating layer containing a Ti oxide
phase and/or a Ti-containing compound oxide phase (however, the
valence of Ti is greater than 2, but less than 4). The present
invention is also characterized in that the self-lubricating film
can be formed and regenerated in process during a machining process
in a high speed region.
[0010] That is, the gist of the present invention lies in a high
speed machining component having a hard material as a base
material, and containing at least one element selected from the
group consisting of fluorine, chlorine, bromine and iodine, the
concentration of the element being in the range of 0.2 mol % to 10
mol % within 1 .mu.m from the surface of the base material. The
gist of the present invention also lies in such a high speed
machining component that if the high speed machining component has
a coating layer containing Ti and C and/or N on the outside of the
base material, the high speed machining component contains at least
one element selected from the group consisting of fluorine,
chlorine, bromine and iodine, the concentration of the element
being in the range of 0.2 mol % to 10 mol % within 1 .mu.m from the
surface of the coating layer. The at least one element selected
from the group consisting of fluorine, chlorine, bromine and
iodine, can be added by ion implantation. The machining component
of the present invention is brought into contact with a workpiece
at a speed of 150 m/min or higher, whereby the high speed machining
component can be produced.
[0011] Further, the gist of the present invention also lies in the
above high speed machining component treated in such a manner as to
be brought into contact with a workpiece at a speed of 150 m/min or
higher.
[0012] The gist of the present invention also lies in the above
high speed machining component further having a self-lubricating
film on a surface in contact with the workpiece. The
self-lubricating film is formed by bringing the high speed
machining component into contact with the workpiece at a speed of
150 m/min or higher. A material containing Ti on a surface layer is
named as the workpiece used for formation of the self-lubricating
film. The self-lubricating film contains a Ti oxide and/or a
Ti-containing compound oxide, the average valence of Ti in the
oxide and/or the compound oxide is greater than 2, but less than 4,
and if the amount of Ti in the self-lubricating film is calculated
as TiO.sub.2, the mass ratio expressed as (mass of the calculated
TiO.sub.2/mass of the self-lubricating film) is 5% or more.
[0013] The gist of the present invention also lies in a high speed
machining method using the above-mentioned machining component. It
also lies in a high speed cutting tool including the above
machining component. With the high speed cutting tool of the
present invention, the wear width V.sub.B of a tool blank after
cutting is performed under conditions including a depth of cut of
1.0 mm, a feed rate of 0.1 mm/rev, a cutting speed of 400 m/min,
and a cutting length of 500 m can be set at 70 .mu.m or less.
Moreover, cutting can be carried out at a cutting speed of 150
m/min or higher without the use of a cutting oil.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 shows a model drawing of a cutting step.
[0015] FIG. 2 shows the cutting speed dependence of a cutting
resistance resultant force in connection with an ion-implanted P10
tool, a TiN-coated P10 tool, and an untreated P30 tool.
[0016] FIG. 3 shows the cutting speed dependence of a feed force in
connection with the ion-implanted P10 tool, the TiN-coated P10
tool, and the untreated P30 tool.
[0017] FIG. 4 shows the cutting speed dependence of a coefficient
of friction in connections with the ion-implanted P10 tool.
[0018] FIG. 5 shows the results of a wear test of the ion-implanted
P10 tool.
[0019] FIG. 6 shows the results of observation of sections of the
ion-implanted P10 tool used in cutting of a Ti-deoxidized
steel.
[0020] FIGS. 7(a) to 7(d) show the results of elemental analysis,
by XMA, of sections of the ion-implanted P10 tool used in cutting
of the Ti-deoxidized steel.
[0021] FIG. 8 shows the results of XPS which measured the surfaces
of a TiN-coated tool (upper) and an ion-implanted TiN-coated tool
(lower) after cutting.
[0022] FIG. 9 shows the results of selected area electron
diffraction performed at 4 locations of the surface layer of an
ion-implanted TiN-coated tool after cutting.
[0023] FIG. 10 shows the results of a cutting test conducted on a
TiCN-coated tool implanted with ions and a TiCN-coated tool not
implanted with ions.
[0024] FIG. 11 shows a tool flank wear width after cutting with the
use of an ion-implanted TiCN-coated tool. A cutting speed was set
at 500 m/min, and a cutting length was set at 500 m or 1,000 m.
[0025] FIG. 12 shows sectional views of flank wear states after
cutting under the conditions of FIG. 11.
[0026] FIG. 13 shows the results of observation of flank and a tool
section (inset) after a cutting test performed in connections with
an ion-implanted TiCN-coated tool, with a Ti-deoxidized steel as a
work material. The observation of the flank was made by a laser
microscope, while the observation of the tool section was carried
out by an optical microscope. The upper part of the inset
corresponds to a region of 26 mm (long).times.60 mm (wide), and the
lower part of the inset corresponds to 80 .mu.m (long).times.100
.mu.m (wide).
[0027] FIG. 14 shows the results of observation of a flank and a
tool section (inset) after a cutting test performed in connection
with an ion-unimplanted TiCN-coated tool, with an Al-deoxidized
steel as a work material. The observation of the flank was made by
a laser microscope, while the observation of the tool section was
carried out by an optical microscope. The upper part of the inset
corresponds to a region of 26 mm (long).times.60 mm (wide), and the
lower part of the inset corresponds to 80 .mu.m (long).times.100
.mu.m (wide).
DETAILED DESCRIPTION
[0028] Hereinbelow, the present invention will be described in
detail.
[0029] The base material of the high speed machining component
according to the present invention can be selected, as appropriate,
in accordance with the material for a workpiece and the shape of
the workpiece after machining, and is preferably a hard material.
The hard material includes cemented carbide tool materials,
ceramics, and ultra-high pressure sintered compacts defined under
JIS B 4053, and refer to sintered materials harder than metallic
materials produced by the melting method. For example, there can be
used alloy tool steels, carbon tool steels, high speed tool steels,
powdery high speed tool steels, cemented carbides, cermets,
ceramics, forging die steels, alloy tool steels for hot dies, alloy
tool steels for cold dies, bearing steels, stainless steels, heat
resisting steels, aluminum and its alloys, titanium and its alloys,
molybdenum and its alloys, and tungsten and its alloys.
[0030] The base material may be coated, or need not be coated. The
material for the coating layer is preferably a high hardness
material such as a material containing Ti and C and/or N. For
example, TiC, TiN, TiCN and TiAlCN are named. In any of these
materials, part of Ti may be substituted by other metallic element.
Moreover, a plurality of coating layers may be stacked.
[0031] If the base material is not coated, at least one element
selected from the group consisting of fluorine, chlorine, bromine
and iodine is added to the surface layer within 10 .mu.m,
preferably within 5 .mu.m, more preferably within 1 .mu.m, from the
surface of the base material. If the base material is coated, at
least one element selected from the group consisting of fluorine,
chlorine, bromine and iodine is added to a surface layer within 10
.mu.m, preferably within 5 .mu.m, more preferably within 1 .mu.m,
from the surface of the coating layer. This element may extend to
the base material, without being confined in the coating layer. If
the region where the element exists is too thin, durability
deteriorates, but if it is too thick, the step of implanting the
element is complicated.
[0032] The concentration of the fluorine, chlorine, bromine and
iodine is 0.2 mol % or higher, preferably 0.5 mol % or higher, more
preferably 1 mol % or higher, but 20 or lower, preferably 10 mol %
or lower, more preferably 8 mol % or lower. If the concentration if
too low, lubricating properties are difficult to improve. If the
concentration is too high, the crystal structure of the base
material and/or the coating layer may be damaged. The concentration
of the element within x .mu.m refers to the maximum element
concentration in the range of the depth 0-x .mu.m when the
distribution was measured by XPS, and the element concentration was
plotted against the depth.
[0033] Ion implantation is named as the method of adding the
fluorine, chlorine, bromine and iodine. Various publicly known
apparatuses and conditions can be used in ion implantation, and the
surface concentration and energy of ion implantation can be
selected, depending on the base material and/or the coating layer,
in order to fulfill the above-mentioned surface layer
concentration. For example, the surface concentration is
1.times.10.sup.15 ions/cm.sup.2 or higher, preferably
1.times.10.sup.16 ions/cm.sup.2 or higher, but 1.times.10.sup.18
ions/cm.sup.2 or lower, preferably 5.times.1.sup.17 ions/cm.sup.2
or lower. Acceleration energy can be set at 20 keV or more,
preferably 30 keV or more, but 500 keV or less, preferably 200 keV
or less.
[0034] An element other than those described above can be used
instead of those elements or in combination with those elements, if
this element is an element which is incorporated into the surface
layer of the machining component in the state where the element can
contribute as an oxidizing agent during the machining step.
[0035] The base material may further contain Ti. The form of Ti is
not limited, but its examples are titanium carbide, metallic Ti,
titanium oxide, and titanium nitride. It suffices that these Ti
compounds are present at least in the surface layer of the base
material, and no restrictions are imposed on the Ti concentration,
as long as it exerts no influence on the characteristics of the
base material. If the base material is cemented carbide, for
example, the Ti concentration can be set at 0.2 mol % or higher,
preferably 1.0 mol % or higher, but 30 mol % or lower, preferably
15 mol % or lower.
[0036] If the machining component of the present invention does not
have the Ti-containing coating layer, it is preferred for the base
material to contain Ti. In this case, Ti can be rendered existent
at the above concentration in the surface layer ranging 20 .mu.m,
preferably 10 .mu.m, more preferably 1 .mu.m, from the surface of
the base material. If the Ti concentration is too low, improvements
in characteristics, such as wear resistance, lubricating properties
and fracture resistance, may be insufficient. If the Ti
concentration is too high, the characteristics of the base
material, such as hardness and strength, may be impaired. However,
Ti may be supplied from the outside by a method, such as the sue of
a workpiece containing Ti. The Ti concentration is the surface
layer ranging y .mu.m from the surface references to the average Ti
concentration in the region with the y .mu.m from the surface.
[0037] If the machining component has the coating layer, the Ti
concentration is 0.2 mol % or higher, preferably 1.0 mol % or
higher, but 80 mol % or lower, preferably 60 mol % or lower, more
preferably 30 mol % or lower, even more preferably 15 mol % or
lower, in the surface layer ranging 20 .mu.m, preferably 10 .mu.m,
more preferably 1 .mu.m, from the surface of the component. The
region where Ti is present at the above concentration may be the
Ti-containing coating layer.
[0038] Surface treatment for bringing the machining component,
which incorporates at least one element selected from the group
consisting of fluorine, chlorine, bromine and iodine, into contact
with the workpiece at a high speed can improve the characteristics,
such as wear resistance, fracture resistance, lubricating
properties and heat resistance. The high speed refers to the
relative speed of the machining component and the workpiece with
respect to each other being 150 m/min or higher, preferably 200
m/min or higher, more preferably 250 m/min or higher. There is no
upper limit on the relative speed, but if it is 1000 m/min or
lower, the durability of the machining component is easy to retain.
The surface treatment at this high speed can be performed without a
lubricating oil.
[0039] If the machining component has no Ti-containing coating
layer, the base material substantially does not contain Ti, and the
workpiece free from the Ti is used, it is preferred to bring the
machining component into contact with a Ti-containing workpiece
beforehand at a high speed (this treatment will be hereinafter
referred to as "high speed pretreatment"), thereby improving
lubricating properties can be improved during the machining
process, even without high speed pretreatment. However, not only
excellent characteristics can be obtained, beginning at a time
immediately after the start of use of the machining component, but
can the characteristics such as lubricating properties be also
optimized, by carrying out the height speed pretreatment.
[0040] If the machining component has the Ti-containing coating
layer, the lubricating properties can be improved during the
machining process without the high speed pretreatment. By
performing the high speed pretreatment, however, not only excellent
characteristics can be obtained, beginning at a time immediately
after start of use of the machining component, but can the
characteristics such as lubricating properties be also
optimized.
[0041] There are no restrictions on the workpiece, but if the
workpiece is a Ti-containing material such as a Ti-deoxidized
steel, there is an advantage for the improvement of the lubricating
properties. The presence of Ti in the surface layer of the
workpiece, in particular, in advantageous for imparting the
lubricating properties in high speed pretreatment and retaining the
lubricating properties during the machining process.
[0042] If, after lubricating properties are imparted to the
machining component, its surface of contact with the workpiece
wears and its lubricity declines, the machining component is
contacted again with a Ti-containing workpiece at a high speed,
whereby lubricating properties can be imparted. From the point of
view of supplying Ti to the interface reaction, it is preferred for
the Ti-containing workpiece to contain Ti at least in its surface
layer.
[0043] The reason why the wear resistance and the lubricating
properties are improved by the above treatment is not entirely
clear. However, it is speculated that a self-lubricating film
formed on the surface of contact between the machining component
and the workpiece may contribute to these improvements. The
self-lubricating film is not a coating layer (for example, the
Ti-containing coating layer) adhered from the outside before the
machining component is put to machining applications, but refers to
a lubricating film formed by a reaction ascribed to the machining
component itself. If the machining component has the coating layer,
the self-lubricating film is formed on this coating layer. If the
machining component has no coating layer, the self-lubricating film
is formed on the base material.
[0044] The lubricating film formed by such a process, unlike the
conventional coating layer, is advantageous in that is worn, it is
regenerated whenever necessary, an d shows stable performance.
Furthermore, the step of forming the coating layer can be omitted,
and the adhesion between the protective layer and the base material
can be enhanced. Besides, the self-lubricating film can suppress
the deposition of the work material on the surface of the machining
component.
[0045] The thickness of the self-lubricating film is not limited as
long as it enables the effects of the present invention to be
exhibited, but the thickness is, for example, 0.05 .mu.m or more,
but 10 .mu.m or less.
[0046] The constituent of the self-lubricating film is not limited,
as long as it imparts wear resistance, lubricating properties, etc.
However, if it can undergo shearing deformation in accordance with
a contact pressure exerted, lubricating properties can be improved.
Thus, the constituent having such deformability is preferred.
Examples of such a constituent are Ti oxides represented by
TiO.sub.x (1<x<2), various Mo oxides, W oxides, and Nb
oxides. As the Ti oxide phase, a Magneli phase represented by
Ti.sub.nO.sub.2n-1 (n: integer) is named. A compound oxide
containing one or more elements selected from the group consisting
of Ti, Mo, W and Nb is also named. The compound oxide may contain
Si and/or Mn, and may, for example, be MnTiO.sub.3. The
self-lubricating film may contain only one of the above phases, and
may contain a plurality of the phases.
[0047] Ti of the self-lubricating film may be supplied from the
machining component of the present invention, of may be supplied
from the work material. If the machining component has the coating
layer, Ti can be supplied from the coating layer. If the machining
component has no coating layer, Ti can be supplied from the base
material. If the Ti oxide and/or the Ti compound oxide is contained
in the self-lubricating film, the average valence of Ti can be
greater than 2, but less than 4. If the machining component has no
Ti-containing coating layer, the proportion, in the
self-lubricating film, of the amount of Ti in the self-lubricating
film calculated as the mass of TiO.sub.2 (hereinafter referred to
as the calculated TiO.sub.2 mass), namely, the following proportion
[0048] calculated TiO.sub.2 mass/mass of the self-lubricating
film.times.100 (%) can be set at 5% or more, preferably 10% or
more. If the machining component has the Ti-containing coating
layer, the proportion of the calculated TiO.sub.2 mass can be 10%
or more, preferably 20% or more, more preferably 40% or more. There
is not upper limit on the calculated TiO.sub.2 mass, and the
self-lubricating film may be composed of a Ti compound alone.
However, the proportion of the calculated TiO.sub.2 mass is often
90% or less, for example, 80% or less, partly because an ingredient
derived from the work material may get in.
[0049] Herein, the value obtained as in Example 3 is used as the
mass of the self-lubricating film. That is, W, Si, Nm, Al and Ti
are measured by XPS, the sum of their masses is calculated on the
assumption that they are present as WC, SiO.sub.2, MnO,
Al.sub.2O.sub.3 and TiO.sub.2, respectively, and the total value is
taken as the mass of the self-lubricating film. The calculated
TiO.sub.2 mass refers to the mass of TiO.sub.2 when all of Ti is
assumed to be present as TiO.sub.2.
[0050] The mechanism by which the self-lubricating film is formed
by fraction at a high speed is not necessarily clear. However,
there may be the following situation: In an environment in which a
high pressure load is imposed on the surface layer of the base
material, for example, the halogen element in the abase material is
reduced into monovalent negative ions. In accordance with this
reduction, Ti is oxidized, with the result that the aforementioned
Ti intermediate oxide lay is formed.
[0051] The high speed machining in the present invention refers to
machining at a relative speed, between the machining component and
the workpiece, of 150 m/min or higher, preferably 200 m/min or
higher, more preferably 250 m/min or higher. If the machining
component of the present invention is used, dry machining (for
example, dry cutting) can be performed without the use of a
lubricating oil.
[0052] The high speed machining component of the present invention
can be sued for any instrument, if it is applied to a site where
friction occurs upon contact between the machining component and
the workpiece at a high speed. For example, the machining component
can be used for cutting tools such as a drill, a milling cutter, a
shaving cutter, a hob and an end mill, various molds such as hot
forging dies and cold forging dies, and sliding components. If the
machining component is used for a cutting tool, the durability of
the cutting tool can be improved to extend its life, and its
machining accuracy can also be improved.
[0053] With the cutting tool of the present invention, the
self-lubricating film is formed on the tool flank, so that wear is
suppressed. The replacement or regrinding of the cutting tool is
usually performed at a time when the flank wear width B.sub.B of
the tool reaches 200 to 300 .mu.m, and V.sub.B serves as a good
indicator of the degree of wear. With the cutting tool of the
present invention, the wear width when dry cutting is performed
under the conditions, a depth of cut of 1.0 mm, a feed rate of 0.1
mm/rev, a cutting speed of 400 m/min, and a cutting length of 500
m, can be set at 70 .mu.m or less, preferably 60 .mu.m or less. In
connection with the wear width V.sub.B .mu.m after dry cutting is
performed under the conditions, a cutting speed of V m/min, and a
cutting length of 500 m, the tool of the present invention can
fulfill the conditions: [0054] V.sub.B.ltoreq.V.sub.B0+0.06375V
where V is 100 m/min or more, but 500 m/min or less, and V.sub.B0
is 30 .mu.m. As noted here, the wear width B.sub.B is suppressed
even at the high cutting speed V, so that the cutting tool can be
rendered long-lived. The dry cutting conditions for the
above-mentioned measurement of the wear width are as described in
Examples 1 and 5.
EXAMPLES
[0055] The present invention will be described in greater detail by
the following Examples, but the present invention is in no way
restricted by these Examples.
<Work Material>
[0056] Work materials used in the Examples are an Al-deoxidized
steel and a Ti-deoxidized steel. These steels were prepared by
melt-forming a steel of the S45C composition by a 100 kg high
frequency induction furnace, deoxidizing the product with Ti and Al
when dividedly pouring it for 50 kg steel ingots, hot rolling the
steel ingots to o75 mm, and normalizing the hot rolled plates. The
chemical compositions of the resulting steels are as shown in
Table1. The use of Ti for deoxidation is found to increase the Ti
concentration in the steel material. TABLE-US-00001 TABLE 1
Chemical analysis values of the work materials (mass %) Type of
steel C Si Mn P S Cu Ni Cr Mo S--Al T--N Ti O Ti- 0.44 0.34 0.80
0.002 0.001 <.01 <.01 <.01 <.01 <.002 0.0009 0.0100
0.0011 deoxidized steel Al- 0.45 0.35 0.80 0.003 <.001 <.01
<.01 <.01 <.01 0.021 0.0006 0.0005 0.0006 deoxidized
steel
<Preparation of Cutting Tool>
[0057] An untreated P10 type-corresponding tool (composition:
WC-TiC (TaC) 30%-Co 10%, Sumitomo Electric Industries, Ltd., shape:
TNUN331 (triangular tip), model: ST10P), a TiN-coated P10
type-corresponding tool (P10 type-corresponding tool
multi-layer-coated with TiCN, Al.sub.2).sub.3, and TiN in this
order, MITSUBISHI MATERIALS CORP., shape: comparable to P10 tool,
model: UE6005), and a TiCN-coated P10 type-corresponding tool (P10
type-corresponding tool vapor-deposited alternatively with
ultra-thin films of TiC and ultra-thin films of TiN, Sumitomo
Electric Industries, Ltd., shape: TNUN331, model: K29J) were
ion-implanted using chlorine. The conditions for the ion
implantation were 100 keV and 1>10.sup.17 ions/cm.sup.2 for all
of the tools. The ion implantation was performed only for the rake
face. The maximum chlorine concentration measured by XPS was 5 mol
%.
[0058] The Ti concentration of the uncoated P10 type-corresponding
tool was 23 mol %, while the surface Ti concentration of the coated
films were 1 to 5 .mu.m.
Example 1
Cutting Resistance Test of the Uncoated Tool
[0059] The ion-implanted P10 tool, and an ion-unimplanted
TiN-coated P10 tool were subjected to a dry cutting test in a low
speed to a high speed region to measure cutting resistance. As a
control, a P30 tool (an untreated product which has not been
ion-implanted or coated, composition WC-TiC (TaC) 8%-Co 10%,
MITSUBISHI MATERIALS CORP., shape: comparable to P10 tool, model:
UT20T) was also subjected to the test. The cutting conditions were
as follows: [0060] Depth of cut Dc: 1.0 mm [0061] Feed rate f: 0.1
mm/rev [0062] Work materials: Al-deoxidized steel and Ti-deoxidized
steel of Table 1 [0063] Cutting speed: Increased from 10 m/min to
300 m/min with the same tool
[0064] A force exerted on the tool during cutting, and the
formation of a self-lubricating film are shown in FIG. 1.
[0065] FIG. 2 shows the cutting speed dependence of a cutting
resistance resultant force (R). All of the tools had maximum values
in the medium speed region (40 to 100 m/min), and the values
decreased as the speed became high. However, the ion-implanted tool
showed a characteristic behavior in the high speed region.
[0066] At 20 to 50 m/min, it is seen that the ion-implanted tool
has a greater cutting resistance resultant force than that of the
TiN-coated tool, and the rate of tan increase in the resistance
resultant force in accordance with the increase in the speed was
also greater. As the cutting speed was further increased, however,
the ion-implanted tool showed lower R. That is, it is found that
the results in the high speed region are different from the results
in the medium speed region; in the high speed region, the
ion-implanted tool obtains higher lubricating tool at 300 m/min
decreased from the value of the TiN-coated tool by 12%.
[0067] A comparison between the P30 type-corresponding tool and the
tool of the present invention shows that an advantageous effect is
obtained in the medium speed range as well. At the cutting speed of
50 m/min or higher, R decreased by about 20% in the tool of the
present invention as compared with the P30 type tool.
[0068] A similar phenomenon was observed with a feed force (Fs;
FIG. 3). At a cutting speed of 300 m/min, the tool of the present
invention was able to reduce Fs by 10 to 15% in comparison with the
TiN-coated tool. Even compared with the P30 type-corresponding
tool, the tool of the present invention was able to reduce Fs by
about 25% at a cutting speed of 50 m/min or higher. As noted from
these results, according to the present invention, the machining
force can be decreased markedly by implanting ions into the base
material, without applying a coating.
[0069] Moreover, regarding the friction coefficient on the
tool-swarf contact surface (.mu.: FIG. 4) geometrically calculated
from the principal force (Fc) and the feed force (Fs), the
ion-implanted tool showed excellent characteristics in the high
speed region. In connection with the friction coefficient at 300
m/min, for example, the value of the ion-implanted tool decreased
by 10% in comparison with the TiN-coated tool, showing that the
ion-implanted tool is excellent in wear resistance. Compared with
the P30 type-corresponding tool, the ion-implanted tool showed a
decrease of about 10% in the friction coefficient at a cutting
speed of 50 m/min or higher. As seen from these results, the
friction coefficient on the tool-cutting contact surface can also
be decreased by the present invention.
[0070] In the cutting test of the ion-implanted tool, the tow types
of work materials with different Ti concentrations (i.e.,
Ti-deoxidized steel and Al-deoxidized steel) were used, and higher
performance was obtained for the work material with a higher Ti
content (Ti-deoxidized steel). These results show that if Ti is
present in the work material, the lubricating properties of the
cutting tool of the present invention are further improved.
Example 2
Wear Characteristics of Ion-Implanted Uncoated Tool
[0071] A wear test, by dry cutting, of the P10 ion-implanted tool
was conducted. The conditions for the test are as follows: [0072]
Cutting speed V: 50-250 m/min [0073] Cutting length: 500 m [0074]
(Cutting time depends on the cutting speed: for example, it is 10
minutes at V=50 m/min, and 2 minutes at B=250 m/min) [0075] Work
materials: Al-deoxidized steel and Ti-deoxidized steel described
above
[0076] Other conditions were the same as those in Example 1.
[0077] The rake face wear depth (k.sub.T) and flank wear width
(V.sub.B) of the tool after the test were measured to evaluate wear
(FIG. 5). As shown in FIG. 5, when the Ti-deoxidized steel is used
as the work material, k.sub.T and V.sub.B are smaller, and thus
wear characteristics are improved.
Example 3
Analysis of Self-Lubricating Film of Ion-Implanted Uncoated
Tool
[0078] In connection with the ion-implanted P10 tool used in the
same cutting as in Example 1, the resulting self-lubricating film
was observed with an optical microscope (FIG. 6). As a result, the
formation of the film on the surface of contact with the work
material was noted.
[0079] The composition of the film was measured by XAM (FIGS. 7(a)
to 7(d). As shown in FIGS. 7(a) to 7(d), Ti--Mn--Si compound oxides
are formed in the vicinity of the surface of contact with the work
material.
[0080] In FIGS. 7(a) to 7(d), W, Si, Mn, Al and Ti were measured in
the film region, and their masses were calculated on the assumption
that they would exist as WC, SiO.sub.2, MnO, Al.sub.2O.sub.3 and
TiO.sub.2, respectively, and the sum of these masses was taken as
100%. The values of the mass % obtained for each compound based on
this assumption were indicated for the respective elements in FIGS.
7(a) to 7(d). In regard to Ti, for example, the mass ration
expressed as [0081]
TiO.sub.2/(WC+SiO.sub.2+MnO+Al.sub.2O.sub.3+TiO.sub.2).times.100
(%) was indicated. Actually, however, W, Si, Mn, Al and Ti can
exist in different forms from WC, SiO.sub.2, MnO, Al.sub.2O.sub.3
and TiO.sub.2. The indication (sSiO.sub.2-bMnO-cTiO.sub.2) in FIGS.
7(a) to 7(d) shows that the Si/Mn/Ti molar ratio is roughly
a/b/c.
Example 4
[0081] Analysis of Self-Lubricating Film of Ion-Implanted
TiN-Coated Tool
[0082] Cutting was performed in the same manner as in Example 1
with the use of the ion-implanted TiN-Coated tool. Then, the
elemental analysis of the self-lubricating film was make by XPS
(FIG. 8), and the crystal structure was examined by selected area
electron diffraction (SAED) (FIGS. 9(a) to 9(d)). FIG. 8 also shows
the results on an ion-unimplanted TiN-coated tool as a control. The
spectra in the upper part and the lower part of FIG. 9 were
measured by the same analytical device under the same conditions,
so that the peak absolute intensities of both spectra can be
compared. On comparison of the peak intensities due to Ti, the
ion-implanted tool, a strong peak due to Fe is observed, suggesting
that the work material is deposited on the surface layer. In the
ion-implanted tool of the present invention, on the other hand,
strong Ti peaks are observed, suggesting that the deposition of the
work material is suppressed, and a Ti-containing self-lubricating
film is formed.
[0083] In FIG. 8, only the peaks of TiO.sub.2 and TiN showed
identity. However, the peaks of Ti of Ti oxide and/or compound
oxide phases having a Ti balance of more than 2, but less than 4
are presumed to become shoulders on a lower binding energy side
than the peak of TiO.sub.2. The presence of these Ti oxide phases
is backed up by the electron diffractions of FIGS. 9(a) to
9(d).
[0084] FIGS. 9(a) to 9(d) also show the phases identified by the
diffraction patterns. Ti oxide phases (including a Magneli phase)
having a Ti valence of greater than 2, but less than 4 are seen to
have been formed. The results of FIGS. 9(a) to 9(d) show the
formation of a self-lubricating film containing Ti oxide
phases.
Example 5
Cutting Test of Ion-Implanted TiCN-Coated Tool
[0085] In connection with the ion-implanted TiCN-coated P10 tool,
cutting was performed under conditions including a depth of cut
(Dc) of 1.0 mm, a feed rate (f) of 0.1 mm/rev, and a cutting length
of 500 m to investigate wear characteristics (FIG. 10). The
aforementioned Al-deoxidized steel and Ti-deoxidized steel were
used as work materials. For purposes of comparison, the test was
also conducted on an ion-unimplanted TiCN-coated tool.
[0086] When ion implantation was not performed, the wear width
V.sub.B sharply increased when the cutting speed exceeded 300
m/min, making cutting difficult at 500 m/min. With the
ion-implanted tool of the present invention, on the other hand,
cutting was possible even at the cutting speed of 500 m/min,
showing that wear was suppressed. Particularly when the work
material was the Ti-deoxidized steel, the increase in the wear
width was slow even at the cutting speed of 300 m/min or higher,
and V.sub.B after cutting over a distance of 500 m at the cutting
speed of 500 m/min in the high speed region remained to be 57
.mu.m. Even if the replacement of the tool is to be carried out
when V.sub.B=200 .mu.m, it is expected that cutting over 1,700 m or
more can be performed.
[0087] FIG. 11 shows the relationship between the tool wear width
V.sub.B and the cutting length at a cutting speed of 500 m/min.
When the work material was the Al-deoxidized steel, V.sub.B
increased nearly proportionately with the increase in the cutting
length. With the Ti-deoxidized steel, on the other hand, the
increase in V.sub.B was seen to slow when the cutting length
exceeded 500 m. A comparison of the amount of increase in V.sub.B
between the cutting lengths of 500 m and 1,000 m shows that the
value of the Ti-deoxidized steel was only 1/6 of the value of the
Al-deoxidized steel.
[0088] As a cause of such a difference, a difference in the nature
of the self-lubricating film formed on the tool flank is named. The
self-lubricating film corresponds to the region described as Belag
in FIG. 12. When a Ti-containing material such as a Ti-deoxidized
steel is used as the work material, it is speculated that a
self-lubricating film containing a Ti-containing oxide phase is
formed, and effectively protects the tool flank from rubbing
against the machined surface.
[0089] In connection with the tool used in the cutting test of
Example 5, the surface of the flank was observed with a laser
microscope, and a section of the tool was observed with an optical
microscope.
[0090] FIG. 13 shows the results of observations with a laser
microscope (scanning laser microscope, 1LM21W, Lasertec Corp.) and
an optical microscope after the above test was performed over a
cutting length of 500 m in connection with the ion-implanted
TiCN-coated P10 tool, with the Ti-deoxidized steel as a work
material. An oblique surface generated on the surface of the flank
reflects a self-lubricating film formed during cutting. A dark,
dense area observed in the sectional view is considered to
correspond to the self-lubricating film.
[0091] FIG. 14 shows the results of observations with the laser
microscope and the optical microscope after the above test was
performed over a cutting length of 500 m in connections with the
ion-unimplanted TiCN-coated P10 tool, with the Al-deoxidized steel
as a work material. In FIG. 14, unlike FIG. 13, the formation of a
clear self-lubricating film was not observed. These results suggest
that the formation of a self-lubricating film is promoted by
ion-implanting a halogen and using a Ti-containing work
material.
INDUSTRIAL APPLICABILITY
[0092] According to the present invention, a high speed machining
component excellent in wear resistance and lubricating properties
can be obtained by ion-implanting a halogen, and/or a Ti-containing
coating layer, and further bringing the so treated product into
contact with a workpiece at a high speed. High speed dr cutting can
be performed by a cutting tool using this component.
* * * * *