Note: Descriptions are shown in the official language in which they were submitted.
95~9
Ihe present invention relates to metal working and,
in particular, to cutting tools and methods of manufacture
thereof.
T~e invention may be used for making cutting tools
from various tool materials.
One of the modern trends in developing metal wor-
king techniques is improvement of operating characteris-
tics of cutting tools by applying wear-resistant coats
to their surfaces.
Hitherto much attention has been paid to refining
tool characteristics by choosing a proper chemical com-
position of coatings to suit particular operating condi-
tions. However, the tool characteristics may also be
refined by improving the structure of coatings.
There is known a cutting tool comprising a base
made of hard alloys and having a wear-resistant coat
~ composed of microcrystals of a refractory compound in-
; cluding metals and elements of the C, N and/or B group.
In such a cutting tool a wear-resistant coat includes
metals from the Ti, Zr, Hf, V, Nb, Ta group.
There is also known a method of manufacturing a
cutting tool (cf. UK accepted application no.l,303,910,
Cl. C23C 11/08, Jan.l, 1973 published Jan. 24,-1973)
comprising the steps of heating a base to a temperature
of 1,000 to 1,100C introducing reagents containing
metals and elements from the C, N, B group, and forming
a coat on the surface of said cutting tool, said
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coat including microcrystal3 of a refractory Metal compound,
the coat being obtained as a result of a chemical reaction
between reagents containing components thereof.
liowever, the foregoing cutting tools manufactured by the
above method have high surface energy, a factor leading to
its active adhesive and diffusive interaction with a material
being machined.
Also known in the art i9 a cutting tool comprising a base
who~e working surface i~ provided vlith a wear-resistant
coat including microcrystals of a refractory metal compound
comprising elements of the C, N, 0, B group.
There i6 also known a method of manufacturing a cutting
tool comprising the steps of evaporating and ionizing metal
in a vacuum environment, and subsequently introducing a gas
reagent into said vacuum environment, the gas reagent contai-
ning elements C, N, 0, B the final step being formation of a
wear-resistant coat as a result of interaction between said
metal and said elements. In this method metals are evapora-
ted by an electron beam, using a special purpose electroe'e
for their ionization, metals interacting with the elements
from the C, N, 0, B group on a cool surface.
But the temperature conditions during coating application
in this method of manufacturing cutting tools result in absor-
btion of energy of interacting metals and elements from the
C, N, 0, 3 group by the cool base which in turn results in
formation of a coating having a high level of free surface
energy and impair~ durability of cutting tools.
9549
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In addition, thi~ method oP manufacturin~, cutting tools
employs the steps of evaporation and ioni~ation of metals
without reaching a suitably high level of their ionization
which also leads to formation of a coating having a high
level of free surface energy, a factor already mentioned
above as detrimental to durability of cutting tools.
Known in the art is another method of manufacturing
cutting tools (cf., for example, thesis by S.V~ Kasianov,
Inve~tigation of Cutting Properties of Tools Having Wear-Re-
sistant Coatings and ~evelopment Trends in the Field, Il:osco~q,
1979, Moskovsky Stanko-Ins-trumentalny Institut, p.50, in Rus-
sian) comprising the steps of evaporation and ionization of
at least one metal in a vacuum environment, heating the base
of the cutting tool and cleaning the working surface thereof
by bombardment by ions of at least one metal, subsequent
introduction of a gas reagent into the vacuum environment
and interaction of at lsast one metal .with at least one ele-
ment until a ~ear-resistant coating is formed.
But even this method of manufacturing cutting tools
cannot help achieve ~he minimum working surface free energy,
a disadvanta~e causing intensive diffusive and adhesive in-
teraction of the working surface and the material being
machined which in turn reduces durability of the prior art
cutting tools.
It is an object of the present invention to provide
cutting tools having higher durability.
Another object of this invention is to provide a method
of manufacturing such cutting tools having higher durability.
.
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There is provided a cutting tool comprising
a base whose working surface has a wear-resistant
coa-ting lncluding microcrystals of a refractory com-
pound comprising at least one metal and at least one
element from the C, N, O, B group, in which, accor-
ding -to the invention, a maximum number of micro-
crystals of the refractory compound comprising at
least one metal and a-t least one element from the
C, N, O, B group, and additionally Si, is oriented
]0 in parallel to -the working surface of the base in
the same crystallographic plane.
It is advantageous that in the cutting
tool according to the invention the crystallographic
plane in which said microcrystals are oriented should
have minimum surface energy.
There is also provided a method of manu-
facturing the proposed cutting -tool, comprising the
steps of evaporating and ionizing at least one metal
in a vacuum environment, heating a base of said cut-
ting tool and cleaning its working surface by bom-
bardment by ions of at least one metal, and subse-
quently introducing a gas reagent into said vacuum
environment, and interacting of at least one metal
with at least one element to form a wear-resistant
coat made of their compound and comprising micro-
crystals, in which, according to the invention, the
base of the cutting tool is heated to a temperature
not less than 100C. below its softening temperature,
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~2~ 9
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a heating tempera-ture of the base during coa-t forma-
tion being maintained within the range of from .said
temperature of the base and +50C., and -the gas-
reagent pressure kept in the range from 13.33 to
--21.33.10 Pa.
In compliance with the invention inter-
molecular interaction between the cutting tool and
a material being machined
r; - ;3
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is minimized, an ac'vantage ~ecreasing intonsity of adhesi~e,
c!~lcmical and diffusive processes occurring betw~en the cut-
ting tool and the material being machined, which, in turn,
enhances durability of the cutting tool forming the subject
of the invention.
The invention ~Nill now be described further with reference
to a specific embodiment thereof, taken in conjunction with
the accompanying drawings ~herein:
The other objects and advantages of the present invention
~rill become apparent from the discussion of a specific embodi-
ment thereof 9 taken in conjunction with the accompanying dra-
~ings, wherein:
FIGURE 1 is a general view of a cutting tool manufactured
in accordance with the proposed method (a partial cut-a~lay
view);
~ IGURE 2 is a general view of the cutting tool of FIGU-
RE 1 with crystallographic planes of microcrystals having
minimum surface energy according to the invention (a partial
cut-away view).
Refe~ring ~o the drawings the cutting tool forming the
subject of the in~ention comprises a base 1 (FIG. 1) whose
orking surface 2 has a coat 3 formed by a TiN compound.
FIGURE 1 is an enlarged sc.^ematic view of TiN microcrys-
tals oriented by similar crystallographic planes 4 parallel
o the base 1.
FIGURE 2 is an enlarged schematic view of the TiN micro-
crystals oriented by a crystallographic plane 5 having min-
' F:Um surfase energy parallel to the base 1-
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~L2~
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The proposed method of manufacturing -the
cutting -tool in compliance with the invention com-
prises the steps of evaporating and ionizing at least
one metal in a vacuum environment. Thereafter the
base of the cut-ting tool is heated, and its working
surface is cleaned by metal-ion bombardment. The
base of the cu-tting tool is heated -to a temperature
which is not less than 100C. below its softening
temperature. The heating temperature of the base
during coat formation is main-tained within the range
from this temperature to +50C. Next, there is
introduced a gas reagent comprising elements C, N,
O, B, Si, its pressure being adjusted in the range
from 13.33 to 1.33-10 2Pa, the following step being
interaction between at leas-t one metal and at least
one element from the C, N, O, B, Si group, which
results in foxmation of a wear-resistan-t coat inclu-
ding microcrystals of a refractory compound compris-
ing at least one metal and at least one element from
the group C, N, O, B, Si, said microcrystals being
oriented by the same crystallographic plane parallel
to the working surface of the base.
The cutting tool forming the subject of
the invention operates in the following manner.
During metal-working procedures, the wear-
resistant coat 3 (FIGS. 1, 2) interacts with a metal
workpiece under high temperature and pressure
conditions occurring in the cutting zone. Orientation
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of a maximum number of microcrys-tals by the same
crystallographic plane 4 parallel to the working sur-
face 2 of the base 1 permits decreasing free energy
of the working surface 2 of the base 1, a feature
reducing in-
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tensity of intermolecular interaction betvJeen the YJorking
surface 2 and the material bein~ machined.
~ hen the crystallographic plane 5 (FIG. 2), ~/herein
said microcrystals are oriented, ha~ minimum surface energy,
intermolecular interaction is minimized, a advantage increa-
sing still further durability of the cutting tool. Examples
belov~ are given to enable better understanding of the pre-
sent invention.
Example 1
There were provided drills, dia, 5 mm, and specimens
for an X-ray diffraction analysis of a steel coating having
the following composition:
... . _ _ . . _ . _
C Cr W V 2ilo ~e
0.85 3.6 6.o 2.0 500 The balarr
., _ _ , , . . . _ _
The steel tempering temperature was 560C.
The drills and the specimen to be subjected to an X-ray
di~fraction analysis were cleaned of contamination, placed
in special containers and simultaneously immersed in a va-
cuum chamber in which a titanium cathode was installed. A va-
cuum of 6,65-10 3 Pa was created in the chamber Y~hereupon an
electric arc was initiated. Thus, the titanium was evaporated
and ionized.
The drills and the specimen subjeGted to zn X-ray diffrac-
tion analysis were fed ith a negative voltage accelerating
positively charged titanium ions. Bombardment of the ~orkin&
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5~L~
surface of the drills and specimen with titanium iona vJas
used to clean their ~urfaces and heat the base. Then the
voltage applied to the drills and the specimen wa~ decre-
ased. Simultaneou~ly nitrogen was introduced into the cham-
ber. Said nitrogen reacted ~ith the -titanium, thereby for-
ming a coat of a refractory compound (TiN) comprising mic-
rocry~tals. The coat of TiN was applied to the working sur-
face of the drills and to the surface of the test specimen
under different heating conditions thereof and at different
nitrogen pressures.
A new set of drills and a new test specimen were used
in each test mode. The degree of orientation of the microcrys-
tals of the refractory TiN compound was evaluated by perfor-
ming an X-ray diffraction analysis of the test specimen
with respect to the height of the diffraction peak of ~-
radiation from the crystallographic plane 4 (5) of a micro-
crystal having~minimum surface energy. The maximum height
of the diffraction peak of X-radiation from the plane 4 (5)
in the given aeries of experiments was taken to be lOO~o. In
other experiment3, the above height was used for referenca
in evaluating the height of diffraction peaks in said plane
containing the TiN microcrystals.
Five drills of each lot of finished articles having a
coat of a refractory TiN compound were tested in drilling
holes, 15 mm deep, in steel having the following composition:
0.42-0.49 Balance
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1~ vert,ical drilling machine was u~ed under tho follo~ing
operating conditions:
speed, 45 m/min;
feed, 0.13 mm.
The table below give~ the results obtained in testing
lots of drills and specimens subjected to an X-ray diffraction
analysis, which were manufactured under nine different ope-
rating conditions. The test results sho~ that the highest
durability of the drills was obtained under the following
conditions: a drill-base heating temperature of 500 to 550C
before introduction of nitrogen; a nitrogen pressure of
1~19 Pa; and a drill-heating temperature of ~50 to 500C at
the time titanium reacts with nitrogen. The highest durabi-
lity was obtained in the case of drills having a coat of a
refractory TiN compound including microcrystals~ a maximum
number of which vJas oriented parallel to the working ~urface
of the base by the plane 4 (53.
Example 2
There were manufactured drills, dia. 5 mm, and specinens
to be subjected to an X-ray diffraction analysisO The hard
alloy used had the follo~ling composition:
WC Co
92~ Balance
~ he softenin~ temperature was t = 700-720C.
The drills and the specimen to be subjected to an ~-ray
diffraction analysis were simultaneously loaded into a 7a-
cuum chamber containing a cathode made of an alloy which
~ ~9 ~ ~ ~
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was 50/o Ti and 50~ Hf. The coat was applied in rnuch the same
manner as in Exa~nple 1, the sole differenoe being that the
cathode installed in the chamber was 50~ Ti and 505~0 Hf.
The surfaces of the drills and the test 6pecimens were coa-
ted with a refractory compound (Ti, Hf) N under different
heating conditions thereof and at different nitrogen pressu-
res. The degree of orientation of microcrystals of the ài-
fficulty fusible compound was evaluated as in ~xample 1.
~ ive drills of each lot of` finished articles having a
coat of the refractory compourd (Ti, ~'f) ~ were tested by
drilline holes in graphite with a vertical drilling machine
under the follo;ing cutting con~itions:
speed, 68 m/min;
feed, 0.18 mm/r;
hole depth, 16 mm.
The table below give8 the results obtained in testing
tha drills and specimens subjected to an X-ray diffraction
analysis under different operating conditions. The test re-
sults shov/ that the highest durability of the drills vas
obtained under the following con~itions: a hard-alloy base
heating temperature of 600 to 700C before introduction of
nitrogen; a nitrogen pressure of 6.65-10 lPa; and a hard-alloy
base heating temperature of 100 to 600C at the time the
coat v~as applied
The highest durability was obtained in the case of
drills having a coat oI a refractory compound (Ti, Hf) N,
that included microcrystals, a maximum nuLnber of which was
oriente~ parallel to the v~orkin~ surface of the base b~ the
plane 4(5) havi~g minimum surface energy~
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Table
. . . . . , _ . . . . . .
No. Tool
metalion coat forma-
bombardment tion (C)
(C)
1 2 3 4
1. Steel drill~ 500 400
coated with TiN
refractory com- 500 400
pound 500 400
500 400
500 400
550 40
550 50
550 400
- 550 500
2. Hard-alloy drill3 650 600
coated with refrac-650- 600
~tory compound,(TiHf)N. 650 600
:: 650 600
~50 600
650 40
650 80
650 100
650 500
750 500
400 400
.
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Table continued
No. Nitrogen pressure Intensity Te3t re- Durability
(Pa) of diffrac- sults gain
tion of X- (number factor
-radiation o~
from micro- holes)
crystal
orientation
plane
6 7 8
1. 1.33-10- ~ 40 450 1.0
2.66~10-2
6.65-10-2 60 650 1.44
3.99,1o~2 gO 750 1.7
: 1.19 lG0 810 1.8
2.66 - 350.
3.99.10~1 30 450 1.0
3.99O10-1 80 700 1.6
3,99.1o~l 90 750 1.7
3.99-10-1 100 800 1.8
2. 1.33-10-2 40 410 1.8
6.65-10-2 60 500 2.08
1~19 . 90 800 3.3
1.33 100 1070 4.4
2.66 - 240
6.65-10-1 30 260 1.1
6.65-10-1 60 500 2.1
6.65-10-1 80 750 3.1
6.65-10-1 100 1070 4.4
6.65-10-1 100 800 3.3
: 6.65-10-1 85 580 2.4
5~9
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This invention can be used Por metal working under
various cutting conditions.
Furthermore, this invention makes it po~sible to improve
the quality oP decorative and antirust coats.
Al80, the invention may improve operating characteristics
of ~riction unit partq.
