JPH08300204A - Cutting tool made of titanium carbonitride cermet - Google Patents

Abstract

PURPOSE: To provide a carbonitride titanium cermet made cutting tool excellent in the thermal shock resisting property by a hard dispersion phase comprising a predetermined vol.% of incomplete core structure grains structured to be enclosed by the outer peripheral part so as to expose a portion of the core part. CONSTITUTION: The hard dispersion phase of a carbonitride titanium cermet made cutting tool consists of incomplete core structure grains 3 structured to be enclosed such that a portion of the core part is exposed from the outer peripheral part 2 and occupy 30-100vol.% of the whole hard dispersion phase. Since the core part 1 is not completely enclosed by the outer peripheral even if this incomplete core structure grains are heated, the thermal stress is relaxed by the opened end even if a difference in the thermal expansion quantity by difference of thermal expansion coefficient between the core part 1 and outer peripheral part 2 is generated to produce the thermal stress. Thus, the incomplete core structure grains are not broken out from the interior and further cracks are not extended every time the cycle of the heating and cooling is repeated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention shows excellent fracture resistance and excellent thermal shock resistance when used in continuous wet cutting with high feed and high depth of cut, especially under severe conditions. The present invention relates to a cutting tool made of titanium carbonitride-based cermet.

[0002]

2. Description of the Related Art In recent years, along with the trend of high efficiency and labor saving of cutting, the cutting time is shortened by increasing the cutting speed, or a process from multi-step cutting such as rough cutting and finish cutting to one-step cutting. The rationalization of cutting is being promoted in all aspects, such as shortening of the tool and automatic tool replacement assuming constant replacement.

On the other hand, the titanium carbonitride-based cermet cutting tool exhibits superior performance to high-efficiency machining by increasing the cutting speed, as compared with cemented carbide, and compared with cemented carbide. It is widely used because it can finish work materials with high precision.

For example, as a titanium carbonitride-based cermet cutting tool, Japanese Patent Publication No. 56-51201 discloses Co.
And a binder phase containing 1 or 2 of Ni as a main component: 1 to 30% by volume, the balance containing Ti as a main component, and 4a, 5a and 6a in the periodic table other than Ti.
One or more kinds of group metals (hereinafter, one or more kinds of 4a, 5a and 6a metals in the periodic table other than Ti is referred to as M), and non-containing C and / or N In a titanium carbonitride-based cermet cutting tool having a composition of a hard disperse phase composed of a metal element, the hard disperse phase has a core portion composed of a composite metal carbonitride solid solution having a high Ti concentration and a low M concentration, and a core portion. And a peripheral portion made of a composite metal carbonitride solid solution having a lower Ti concentration and a higher M concentration than that of, and the outer peripheral portion is composed of cored structure particles having a structure completely surrounding the core portion. ing.

The reason why the hard dispersed phase particles are controlled to have a core structure is as follows. That is, when the hard disperse phase particles are single hard disperse phase particles having a high titanium concentration, the titanium compound has poor wettability with respect to the binder phase, so that the force of the binder phase to hold the hard disperse phase particles is weakened, and the cermet strength is increased. Is reduced. The hard dispersed phase particles having a cored structure have a hard dispersed phase particle having a cored structure composed of a core portion and an outer peripheral portion, and lower the titanium content in the outer peripheral portion of the cored structure of the hard dispersed phase particle and wet the binder phase. By increasing the concentration of the M element having good properties, the adhesive force of the hard dispersed phase particles to the binder phase is increased, the wettability of the entire hard dispersed phase particles is improved, and the strength is improved.

[0006]

However, the conventional titanium carbonitride-based cermet cutting tool is vulnerable to thermal shock, so that the tool often breaks in wet cutting using a cutting fluid, and the stability of the cutting edge is reduced. being insufficient.

[0007]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of research to obtain a cutting tool made of titanium carbonitride-based cermet that has better thermal shock resistance than before, it was found that the core part was incompletely surrounded so that it was exposed from the outer periphery. At least 3 hard dispersed phases consisting of core structure particles
The cutting tool made of titanium carbonitride-based cermet containing 0% by volume is
Compared with conventional titanium carbonitride cermet cutting tools,
We have obtained the knowledge that it has excellent thermal shock resistance.

The present invention has been made on the basis of such findings, and contains a binder phase containing 1 or 2 of Co and Ni as main components: 1 to 30% by volume, and the balance of Ti. It has a structure composed of a hard disperse phase containing M and C and / or N as a main component, and the hard disperse phase is composed of a composite metal carbonitride solid solution having a high Ti concentration and a low M concentration. In a cutting tool made of a titanium carbonitride-based cermet, which comprises a core portion made of a composite metal carbonitride solid solution having a lower Ti concentration and a higher M concentration than the core portion, the hard dispersed phase is a core portion. To a cutting tool made of titanium carbonitride-based cermet containing 30 to 100% by volume, and more preferably 50 to 100% by volume of incompletely cored structural particles having a structure incompletely surrounded so that a part of is exposed from the outer peripheral portion. Features It is intended to.

If the proportion of incompletely cored structured particles having a structure in which the core portion is incompletely surrounded by the hard dispersed phase so as to be exposed from the outer peripheral portion is less than 30% by volume, the effect on the thermal shock resistance is improved. Since it is not sufficient, the proportion of incompletely cored structured particles in the hard dispersed phase is preferably 30% by volume or more (including 100% by volume).

Next, 30 to 30 particles of incompletely cored structure particles having a structure in which the titanium carbonitride-based cermet cutting tool of the present invention is incompletely surrounded so that a part of the core portion is exposed from the outer peripheral portion.
The hard dispersed phase containing 100% by volume is visually described with reference to the drawings. FIG. 1 is an explanatory view of the structure of the titanium carbonitride-based cermet cutting tool of the present invention, and the hard dispersed phase of the titanium carbonitride-based cermet cutting tool of the present invention, as shown in FIG. Incomplete core-structured particle 3 having a structure incompletely surrounded so that a part of 1 is exposed from the outer peripheral portion 2.
Is composed of a hard dispersed phase which occupies at least 30% by volume of the entire hard dispersed phase.

Charcoal comprising a hard dispersed phase containing imperfect cored structured particles 3 having a structure in which a part of the core part 1 of the present invention shown in FIG. 1 is incompletely surrounded so as to be exposed from the outer peripheral part 2. In the titanium nitride cermet cutting tool, even if heat is applied to the incompletely cored structure particles 3, the core portion 1 is not completely surrounded by the outer peripheral portion 2, so that the thermal expansion of the core portion 1 and the outer peripheral portion 2 occurs. Even if thermal expansion occurs due to a difference in coefficient of thermal expansion due to a difference in coefficient, the thermal stress is relieved by the open end, so that no fracture occurs from the inside of the imperfect cored structured particle 3 and further heating is performed. It is considered that the thermal shock resistance is improved without the crack expanding each time the cooling cycle is repeated.

On the other hand, the conventional hard disperse phase shown in FIG. 2 has completely cored particles 4 having a structure in which the core 1 is completely surrounded by the outer periphery 2. When heat is applied to the titanium carbonitride-based cermet of the completely core-structured particles 4 shown in FIG. 2, the difference in thermal expansion coefficient between the core 1 and the outer peripheral portion 2 causes a difference in thermal expansion amount between the core 1 and the outer peripheral portion 2. Occurs, fracture occurs from the inside of the completely core-structured particle 4, and a crack spreads every time the heating / cooling cycle is repeated,
Therefore, it is considered that the cutting edge of the tool is damaged before the ultimate life of wear resistance is finally reached.

The T of incomplete core-structured particles constituting the hard dispersed phase of the titanium carbonitride cermet cutting tool of the present invention.
The core having a high i concentration and a low M concentration is composed of a composite metal carbonitride solid solution containing Ti: 85 to 100% by weight and M: 0 to 15% by weight as a metal component.
The outer peripheral portion having a low i concentration and a high M concentration is preferably composed of a composite metal carbonitride solid solution containing Ti: 15 to 50 wt% and M: 50 to 85 wt% as metal components.

In the titanium carbonitride-based cermet cutting tool of the present invention, raw material powders are blended, mixed and press-molded to produce a green compact having a predetermined composition, and the green compact is sintered in a sintering furnace. It is inserted into and sintered, but it can be produced by controlling the dissolution and precipitation reaction in this sintering step.
That is, as the dissolution and precipitation reaction proceeds in the sintering step, the hard dispersed phase changes from incompletely cored structure particles to completely cored structure particles, but in the present invention, the dissolution and precipitation reaction does not proceed excessively. It can be manufactured by stopping the dissolution and precipitation reaction in the sintering step on the way.

At this time, since it is necessary to densify the sintered body without excessively promoting the dissolution-precipitation reaction, it is possible to prevent the particle size of the raw material powder of titanium carbonitride from being unnecessarily miniaturized and having a narrow particle size distribution. It is necessary to select a titanium nitride powder. Further, in order to prevent an excessive dissolution and precipitation reaction in the sintering step, it is preferable to perform the sintering on the low temperature side in the shortest possible time.

Furthermore, the cutting tool made of the titanium carbonitride-based cermet of the present invention is used as a substrate, and TiC, TiN, TiC is formed on the surface thereof by means of ordinary physical vapor deposition or chemical vapor deposition.
A coated cermet cutting tool can be manufactured by coating a hard layer of N, TiCO, TiCNO, Al ₂ O ₃ , TiAlN or the like.

[0017]

EXAMPLE As a raw material powder, TiCN (TiC / TiN = 5) having a predetermined average particle diameter within the range of 0.5 to 2 μm was used.
0/50) powder, TiN powder, TaC powder, NbC powder, WC powder, Mo ₂ C powder, VC powder, ZrC powder,
Cr ₃ C ₂ powder, (Ti, W, Mo) CN (however, T
i: W: Mo = 6: 3: 1, C: N = 6: 4) powder,
(Ti, Nb, W, Mo) CN (however, Ti: Nb:
W: Mo = 6: 2: 1: 1, C: N = 5: 5) powder,
(Ti, Ta, Nb) CN (however, Ti: Ta: Nb
= 8: 1: 1, C: N = 5: 5) powder, Co powder, Ni
Powder and graphite powder were prepared, and these raw material powders were blended so as to have the blending composition shown in Table 1, wet-mixed in an attritor mill for 15 hours, dried, and then dried at 1.5 ton / cm ² . Powder compacts A to H were produced by press molding with pressure.

[0018]

[Table 1]

These green compacts A to H are sintered under the conditions shown in Table 2 and processed into ISO standard CNMS120408.
The present invention cermet cutting tools (hereinafter referred to as the present invention cutting tools) 1 to 8 and the comparative cermet cutting tools (hereinafter referred to as the comparative cutting tools) 1 to 5 having the above shapes were manufactured.

[0020]

[Table 2]

Further, commercially available conventional cermet cutting tools (hereinafter referred to as conventional cutting tools) 1 to 3 were also prepared. By image analysis of these cutting tools 1 to 8 of the present invention, comparative cutting tools 1 to 5 and conventional cutting tools 1 to 3, the proportion of the hard dispersed phase in the titanium carbonitride cermet substrate, the titanium carbonitride cermet substrate The proportion of incompletely cored structured particles in the hard dispersed phase and the proportion of incompletely cored structured particles in the entire hard dispersed phase were measured, and the results are shown in Table 3.
~ 4.

Using these cutting tools 1 to 8 of the present invention, comparative cutting tools 1 to 5 and conventional cutting tools 1 to 3, a work material: SNCM439, a cutting speed: 250 m / min. , Feed: 0.3 mm / rev. , Depth of cut: 2 mm, cutting oil: water-soluble, wet high speed continuous cutting of steel is performed, and cutting time is 10
The flank wear width of the cutting edge at 20 and 20 minutes,
The results are shown in Tables 3 to 4, and at that time, the presence or absence of damage to the cutting edge was examined, and the results are shown in Tables 3 to 4 to evaluate the strength of the cutting edge against thermal shock (thermal shock resistance).

[0023]

[Table 3]

[0024]

[Table 4]

From the results shown in Tables 3 to 4, the cutting tools 1 to 8 of the present invention in which the ratio of incomplete cored structured particles to the entire hard dispersed phase is 30% by volume or more do not have incomplete cored structured particles. It can be seen that compared with the conventional cutting tools 1 to 3, there is no damage due to thermal shock, and the wear resistance is significantly improved. However, as seen from the comparative cutting tools 1 to 5, it is understood that when the conditions of the present invention are not satisfied, sufficient thermal shock resistance and wear resistance are not exhibited.

[0026]

The titanium carbonitride-based cermet cutting tool of the present invention can greatly improve the tool life as compared with the prior art, and has industrially excellent effects.

[Brief description of drawings]

FIG. 1 shows the structure of a titanium carbonitride-based cermet cutting tool of the present invention containing 30% by volume or more of incompletely cored structured particles having a structure in which the outer peripheral portion is incompletely surrounded so that a part of the core portion is exposed. It is an explanatory view for explaining.

FIG. 2 is an explanatory diagram for explaining the structure of a conventional titanium carbonitride-based cermet cutting tool composed of completely cored structured particles having a structure in which a core part is completely surrounded by an outer peripheral part.

[Explanation of symbols]

 1 core part 2 outer peripheral part 3 incomplete core-structured particle 4 perfect core-structured particle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisashi Tsujizaki 1511 Furumagi, Ishishita-machi, Yuki-gun, Ibaraki Pref. 1511, Tsukuba Works, Mitsubishi Materials Corporation (72) Katsuhisa Nonaka 1511 Furumagi, Ishishita-machi, Yuki-gun, Ibaraki Address Mitsubishi Materials Corporation Tsukuba Works

Claims (1)

[Claims] 1. A binder phase containing 1 or 2 of Co and Ni as main components: 1 to 30% by volume, the balance being T.
i as a main component, 4a, 5 in the periodic table other than Ti
One or more of the metals a and 6a (hereinafter, 4a, 5a and 6a in the periodic table other than Ti)
One or more of the group metals are described as M) and a hard dispersed phase composed of a nonmetallic element of C and / or N, and the hard dispersed phase has a high Ti concentration and M Consisting of particles composed of a core portion made of a composite metal carbonitride solid solution having a low concentration and an outer peripheral portion made of a composite metal carbonitride solid solution having a lower Ti concentration and a higher concentration of M than the core portion. In the titanium carbonitride-based cermet cutting tool, the hard dispersed phase is composed of incompletely cored particles having a structure in which the hard dispersed phase is incompletely surrounded by the outer peripheral portion so that a part of the core portion is exposed.
A cutting tool made of titanium carbonitride-based cermet, characterized in that the cutting tool contains 100% by volume.