JPH08192304A - Titanium carbonitride cermet cutting tool provided with excellent crack resistance - Google Patents

Abstract

PURPOSE: To carry out intermittent cutting requiring breakage resistance without causing any breakage or chipping in a cutting tool by forming the specific volume percent or more of a cored hard phase possessing a reverse M constituent concentration distribution, in which the M constituent content is gradually increased from the inside to the outside in a ring, in a hard phase. CONSTITUTION: In a titanium carbonitride cermet cutting tool consisting of 5-30 volume % of a binding phase, in which Co and/or Ni are/is principle constituent(s), and the rest of a hard phase, the main body of the hard phase is provided with a cored structure consisting of a core part and a ring part. The core part and the ring part are formed of cored hard phases consisting of composite carbonitride composed of Ti and M constituent (one or more kind/kinds of metal/metals selected from 4a, 5a, and 6a groups metal in the periodic table except Ti). In this process, the cored hard phase ring part occupying 60 volume % or more in the whole hard phase is prepared so as to be provided with a reverse M constituent concentration distribution, in which the M constituent content is gradually increased from the inside to the outside, so that breakage resistance is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can be used for intermittent cutting of steel, for which fracture resistance is particularly required. The present invention relates to a cutting tool made of titanium carbonitride-based cermet (hereinafter, simply referred to as cermet) that exhibits excellent cutting performance for a long period of time without the occurrence of such).

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-62-170452.
As disclosed in JP-A No. 63-83241 and JP-A No. 1-162744, a binder phase containing Co and / or Ni as a main component: 5 to 30% by volume
And the rest is composed of a hard phase, and the main body of the hard phase has (a) a cored structure of a core part and a ring part, and the core part and the ring part have Ti and M components (however, The M component is a group 4a, 5a, and 6a metal of the periodic table excluding Ti, that is, Zr, Hf, V, Nb, Ta, Cr, and M.
a core hard phase composed of a composite carbonitride (hereinafter, represented by (Ti, M) CN) with (1 or more of O and W), and (b) of the core and the ring. It has a cored structure, and the core part is substantially Ti carbonitride (hereinafter, TiCN
Is shown) and the ring portion is composed of a cored hard phase made of (Ti, M) CN and a cermet made of the above (a) and / or (b).

[0003]

FA of cutting equipment in recent years
However, there is a strong demand for labor saving and cost reduction, and accordingly, there is a tendency for a cutting tool capable of continuous cutting and interrupted cutting. For cutting tools,
Although continuous cutting has no problem, when it is used for intermittent cutting, the cutting edge is apt to be chipped or chipped, and the service life is relatively short.

[0004]

Therefore, the present inventors have
From the above viewpoint, as a result of research to develop a cutting tool made of cermet having excellent fracture resistance, (1) the conventional cutting tool made of cermet described above is usually prepared from a green compact having a predetermined composition. The temperature rising process from room temperature to 1100 ° C was conducted with a nitrogen atmosphere of 0.05 to 0.1 torr, and
A condition in which a nitrogen atmosphere of 5 torr is used for the temperature raising process from 00 ° C. to 1420 to 1550 ° C., the holding process at the sintering temperature, and the cooling process from the sintering temperature to room temperature (hereinafter, referred to as A It is manufactured by sintering under the conditions). (2) Regarding the conventional cermet cutting tool sintered under the above condition A, when observing the ring portion of the cored hard phase of the cermet constituting the conventional cutting tool, the ring portion extends from the inner side (core side) to the outer side. To have an M component concentration distribution in which the above M component content gradually decreases. (3) A green compact having a predetermined composition (having a smaller amount of carbon blended than usual) was heated from room temperature to 1350 ° C. in a nitrogen atmosphere of 0.05 to 0.1 torr, and
The temperature rising process from 50 ° C. to 1420 to 1550 ° C. was made into a mixed gas introduction atmosphere of methane, hydrogen and nitrogen of 0.1 to 20 torr, and the holding process at the sintering temperature was made to be 1-2.
Cermet cutting by sintering in a mixed gas introduction atmosphere of 0 torr and in a nitrogen atmosphere of 0.05 to 0.1 torr in the cooling process from the sintering temperature to room temperature (hereinafter referred to as condition B) When the tool is manufactured, the M component concentration distribution is reversed in the ring portion of the cored hard phase of the cermet that constitutes the resulting cermet cutting tool, and the M component content increases from the inner side (core side) to the outer side. To have a gradually increasing inverse M component concentration distribution. (4) When 60% by volume or more of the ring portion of the cored hard phase of the cermet forming the cermet cutting tool has the inverse M concentration distribution in the ratio of the whole hard phase, the cermet cutting is performed. The tool should have excellent fracture resistance while having excellent wear resistance. The research results shown in (1) to (4) above were obtained.

The present invention has been made based on the above-mentioned research results, and contains a binder phase containing Co and / or Ni as a main component: 5 to 30% by volume, and the rest consisting of a hard phase, And, the main body of the hard phase has (a) a cored structure of a core portion and a ring portion, and the core portion and the ring portion are composed of (Ti, M) CN, and (b) a core portion. It has a cored structure of a ring part, and the core part is substantially TiC.
A cored hard phase composed of N, wherein the ring portion is composed of (Ti, M) CN, and a cermet composed of the above (a) and / or (b). The ring portion of the cored hard phase having a volume ratio of 60% by volume or more in the entire hard phase has an inverse M component concentration distribution in which the M component content gradually increases from the inside to the outside, and has excellent fracture resistance, It is also characterized by a cermet cutting tool with excellent wear resistance.

In the cutting tool of the present invention, the proportion of the binder phase of the cermet constituting the cutting tool is 5 to 30% by volume.
When the ratio is less than 5% by volume, the sinterability deteriorates, and as a result, the strength is inevitably decreased. On the other hand, when the ratio exceeds 30% by volume, the wear resistance sharply decreases. Is due to
Also, of the hard phase of cermet, the ring part is reverse M
The ratio of the cored hard phase having the component concentration distribution is set to 60% by volume or more based on the entire hard phase. If the ratio is less than 60% by volume, the desired excellent fracture resistance is secured as described above. It is based on the reason that it is not possible. Further, the cermets constituting the cutting tool of the present invention each have a single phase of TiCN or (T
i, M) CN, TiN, etc. may be contained in some cases, but the content ratio of these is 30 in the entire hard phase.
Since it is not desirable to contain it in excess of volume% from the viewpoint of wear resistance and fracture resistance, the content must be limited to 30 volume% or less.

[0007]

EXAMPLES Next, the cutting tool of the present invention will be specifically described by way of examples. As raw material powder, 0.5-
Having a predetermined average particle size within the range of 2 μm, and
Various kinds of carbide powder, nitride powder, carbonitride powder, (Ti, M) CN powder, TiCN powder, Co
A powder and a Ni powder were prepared, and these raw material powders were blended to the blending composition shown in Tables 1 and 2, and the powder was milled with a ball mill
After wet-mixing for a period of time and drying, the green compact was press-molded at a pressure of 1.5 ton / cm ² , and then these green compacts were subjected to the above-mentioned conditions A or B as shown in Tables 1 and 2. By sintering, the cutting tool 1 of the present invention having a throw-away tip shape in conformity with the standard of SNMG432
-15 and conventional cutting tools 1-8, respectively.

Next, regarding the various cutting tools obtained as a result, 10 μm × 10 of the cermet constituting the cutting tools is formed.
The hard phase was analyzed at 5 arbitrary points of μm using an Auger electron spectroscopy analyzer, and the type and content ratio of each hard phase were measured using an image analyzer from the results of this analysis. The results of these measurements are shown in Tables 3 and 4. The "normal M component concentration distribution" in Tables 3 and 4 is the same as that found in the ring portion of the cored hard phase of the cermet that conventionally constitutes a cermet cutting tool, and the M component content gradually decreases from the inside to the outside. Showing the M component concentration distribution
Similarly, the "inverse M component concentration distribution" indicates the M component concentration distribution in which the M component content gradually increases from the inside to the outside of the ring portion of the cored hard phase, contrary to the normal M component concentration distribution. is there.

Further, regarding these various cutting tools, a work material: a round bar of SNCM439 (hardness: H _B 270), a cutting speed: 180 m / min, a cut: 1.5 mm, a feed: 0.3 mm / rev ., Cutting time: 20 minutes, continuous dry cutting test of steel, and Work material: SNCM439 (hardness: H _B 270) with three longitudinally spaced round bars with longitudinal grooves, Cutting speed : 150 m / min, Depth of cut: 3 mm, Feed: 0.15 mm / rev., Cutting time: 5 minutes, dry intermittent cutting test of steel was performed, and the flank wear width of the cutting edge was measured in each test. .

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

[Table 5]

[0015]

From the results shown in Tables 3 to 5, the cutting tools 1 to 15 of the present invention are all 60% by volume of the hard phase.
The above is composed of a cored hard phase having a reverse M component concentration distribution in which the M component content gradually increases from the inner side to the outer side, and not only continuous cutting but also intermittent cutting requiring fracture resistance. It shows excellent wear resistance without chipping or chipping on the cutting edge during cutting, whereas conventional cutting tools 1-8
Although it shows excellent wear resistance in continuous cutting, it is clear that in intermittent cutting, the cutting edge is chipped in a relatively short time after the start of cutting due to lack of fracture resistance, and it reaches its useful life. is there. As described above, the cermet cutting tool of the present invention exerts excellent cutting performance not only for continuous cutting but also for interrupted cutting in particular for a long period of time, which brings about an expansion of the range of application of the cutting process and can be widely performed. It enables cutting over a wide range.

Claims (1)

[Claims] 1. A binder phase containing Co and / or Ni as a main component: 5 to 30% by volume, the rest consisting of a hard phase, and the main component of the hard phase is (a) a core part and a ring part. The core portion and the ring portion have Ti and M components (however, the M component is Ti).
A composite carbonitride containing one or more of 4a, 5a, and 6a metals of the periodic table excluding (1) and (2) a core of a core and a ring. A cored hard phase having a structure, in which the core portion is substantially made of Ti carbonitride, and the ring portion is made of a composite carbonitride of Ti and the M component; and (a) and / or (b) ), A cutting tool composed of a titanium carbonitride-based cermet comprising 60% of the above cored hard phase in the whole hard phase.
Ring part of cored hard phase with capacity% or more is inside (core side)
Inverse M in which the M component content gradually increases from the outside to the outside
A titanium carbonitride-based cermet cutting tool with excellent fracture resistance characterized by having a component concentration distribution.