JP3223626B2 - Tungsten carbide based cemented carbide cutting tool with excellent wear resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tungsten carbide-based cemented carbide cutting tool exhibiting excellent wear resistance (hereinafter referred to as a cemented carbide cutting tool).

[0002]

2. Description of the Related Art Conventionally, generally, for example, JP-A-56-20
As described in JP-A-141 and JP-B-58-2580, by volume% (hereinafter,% indicates volume%),
Bound phase consisting essentially of Co: 8-20%, Ti and Ta
WC having a composition consisting of: a hard phase of carbonitride of W and W [hereinafter referred to as (Ti, Ta, W) CN]: 10 to 35%, tungsten carbide (hereinafter referred to as WC) and inevitable impurities: remaining Base cemented carbide (hereinafter referred to as cemented carbide)
Is known, and it is well known that this is applied as various throw-away tips and drills.

[0003]

On the other hand, in recent years, for example, in the field of cutting, the use of FA has been remarkable, and the demand for labor saving has been severe. Accordingly, it has been strongly desired to extend the service life of cutting tools. However, in the case of the conventional carbide cutting tools described above, the wear resistance is not yet sufficient, and at present, it is not always possible to satisfy these requirements satisfactorily.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above point of view, focusing on the above-mentioned conventional carbide cutting tools, as a result of conducting research to further improve the wear resistance of the conventional carbide cutting tools, the above-mentioned conventional carbide cutting tools are generally used as a raw material powder. , WC powder, (Ti, W) CN powder, (T
i, Ta, W) CN powder, Co powder, and Ta
C powder, TaN powder and TaCN powder are used, provided that the (Ti, W) CN powder and (Ti, Ta, W)
CN powder has a C / (C + N) molar ratio of 0.1 to 0.5,
Ti / (Ti + W) molar ratio: 0.58 to 0.99, (T
(i + Ta) / (Ti + Ta + W) molar ratio: 0.58-
Satisfies the condition of 0.99, these raw material powders are blended in a predetermined composition, mixed, and then pressed into a green compact, and the green compact is, for example, placed in a nitrogen atmosphere of 0.1 to 500 torr. It is manufactured by holding at a temperature of 1300 to 1500 ° C. for a predetermined time and then sintering under cooling conditions. The above raw material powders (Ti, W) CN powder and (T
i, Ta, W) Instead of CN powder, C / (C + N) molar ratio: 0.01 to less than 0.1 (Ti / (Ti + W)
And the (Ti + Ta) / (Ti + Ta + W) molar ratio is the same), that is, C is relatively small compared to the N content.
(Ti, W) CN powder with significantly lower content and (T
When a cemented carbide cutting tool is manufactured using i, Ta, W) CN powder and the other conditions are the same, (Ti, Ta) in the cemented carbide constituting the cemented carbide cutting tool is manufactured. , W) The CN hard phase is a single phase in the cemented carbide constituting the conventional cemented carbide cutting tool. However, the central part and the peripheral part having relatively higher hardness than the central part are used. And the concentrations of the constituent W and C components are higher in the center than in the periphery, while the concentrations of Ti, Ta and N components are higher in the center. In contrast, the peripheral portion has a higher component concentration distribution, and thus a double structure (Ti,
Ta, W) The cemented carbide cutting tool composed of the cemented carbide in which the CN hard phase is present has the same toughness as the conventional cemented carbide cutting tool composed of the above-mentioned conventional cemented carbide, and is obtained by The research results show that they exhibit even more excellent wear resistance, exhibit excellent cutting performance over a long period of time, and significantly extend tool life.

The present invention has been made based on the results of the above research, and has a bonded phase consisting essentially of Co:
8-20%, (Ti, Ta, W) CN hard phase: 10-3
5%, WC hard phase and unavoidable impurities: having the following composition: and the (Ti, Ta, W) CN hard phase has a double structure consisting of a central part and a peripheral part,
Concentrations of the constituent W and C components are higher in the central portion than in the peripheral portion, while concentrations of Ti, Ta, and N components are higher in the peripheral portion than in the central portion. The present invention is characterized by a carbide cutting tool having excellent wear resistance made of a cemented carbide having the following characteristics.

Next, the reason why the component composition of the cemented carbide constituting the cemented carbide cutting tool of the present invention is limited as described above will be described. (A) Binder phase The binder phase is substantially Co (Co, which is a raw material powder during sintering).
Other components are dissolved in the powder), and the presence of the component provides strength and toughness. However, if the proportion is less than 8%, desired strength and toughness cannot be secured. If the proportion exceeds 20%, the proportion of the hard phase becomes relatively small and the abrasion resistance decreases, so the proportion is set to 8 to 20%.

(B) (Ti, Ta, W) CN hard phase The (Ti, Ta, W) CN hard phase has a function of further improving the wear resistance. An excellent effect of improving wear resistance cannot be obtained. On the other hand, if the proportion exceeds 35%, a tendency to decrease in toughness appears, so the proportion is set to 10 to 35%.

[0007]

Next, the carbide cutting tool of the present invention will be described in detail with reference to examples. As raw material powder,
WC powder having a predetermined average particle size in the range of 3 μm, T
For the production of aC powder, TaN powder, TaCN powder, and Co powder, and the carbide cutting tool of the present invention, the following carbonitride A to D powders: (1) Carbonitride A powder TiC / TiN / WC = 31/1/68, C / (C + N) = 0.15 (Ti, W) C in molar ratio
N powder (2) Carbonitride B powder TiC / TiN / WC = 40.5 / 3.5 /
(Ti, W) CN powder having a molar ratio of C / (C + N) = 0.55, (3) carbonitride C powder TiC / TiN / TaC / WC = 28.5 /
1.5 / 4.5 / 65.5, in molar ratio, C / (C + N)
(Ti, Ta, W) CN powder of 0.020; (4) Carbonitride D powder TiC / TiN / TaC / WC = 28/5 /
(Ti, Ta, W) CN powder having a C / (C + N) = 0.090 in a molar ratio of 46/21, and the C / (C + N) molar ratio in any of the above (1) to (4) is 0.01. (Ti, W) CN powder and (Ti, Ta,
W) CN powder was prepared.

Conventionally, for the manufacture of carbide cutting tools, the following carbonitride a to d powders, namely: (a) carbonitride a powder, TiC / TiN / WC = 29/20 / 51,
(Ti, W) with a molar ratio of C / (C + N) = 0.305
CN powder, (b) Carbonitride b powder TiC / TiN / TaC / WC = 26.5 / by weight ratio
8.5 / 4.5 / 60.5, molar ratio C / (C + N)
(Ti, Ta, W) CN powder of 0.15, (c) carbonitride c powder TiC / TiN / TaC / WC = 14/16 by weight ratio
(51,19), (Ti, Ta, W) CN powder of C / (C + N) = 0.30 in molar ratio, (d) carbonitride d powder TiC / TiN / TaC / WC = 5 in weight ratio / 23 /
(Ti, Ta, W) CN powder having a C / (C + N) = 0.45 in a molar ratio of 62/10, and the C / (C + N) molar ratio in any of (a) to (d) is 0.1. (Ti, W) CN powder and (Ti, Ta, W) CN in the range of ~ 0.5
Powder was prepared.

Then, these raw material powders are blended in the composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and then pressed into a green compact at a pressure of 1 ton / cm ^2. The powder is sintered in a nitrogen atmosphere at a predetermined N ₂ partial pressure in the range of 10 to 100 torr and maintained at a predetermined temperature in the range of 1380 to 1430 ° C. for 1 hour, as shown in Table 1. Carbide cutting tools 1 to 6 of the present invention and conventional carbide cutting tools 1 to 4 which are made of a cemented carbide having the following composition and have a throw-away insert shape defined in ISO SNGN 120408 were manufactured.

An arbitrary cross section of each of these carbide cutting tools is polished, and (Ti, Ta, W) CN on the polished surface is polished.
Observation of the hard phase revealed that the carbide cutting tools 1 to 6 of the present invention all showed a double structure in which the central portion and the peripheral portion were clearly divided, whereas the conventional carbide cutting tools 1 to 4 No double structure appeared in the (Ti, Ta, W) CN hard phase, and each showed a single phase.

Further, any (Ti,
Ta, W) CN hard phase is selected, and the selected hard phase is analyzed using an electronic analyzer (EPMA).
With a beam diameter of μm, the composition (constituent component content) of the central part and peripheral part of the hard phase was measured. The composition of the center of the hard phase was measured with the beam center positioned almost at the center of the hard phase. For the composition of the periphery, the beam center was placed at the center where the three hard phases were in contact with each other, and the beam circle was measured. The measurement was carried out in such a manner that the circumferential portions of three hard phases were respectively entered into the inside by about 1/3. Table 2 shows the results of these measurements.

Furthermore, the above-mentioned various carbide cutting tools, work material: SCM440 (hardness: H _B 300) round bar, Cutting speed:. 150 meters / min, Feed: 0.3 mm / re
. v, cut: 3 mm, Cutting time: 10 minutes, dry continuous cutting test of steel under the conditions of, as well as work material: SCM440 (hardness: H _B 220) in the length direction at equal intervals of four longitudinal grooves filled Round bar,
Dry intermittent cutting test of steel under the conditions of cutting speed: 100 m / min., Feed: 0.3 mm / rev., Depth of cut: 1 mm, cutting time: 10 minutes, and flank wear of cutting edge in all tests The width was measured. The results of these measurements are also shown in Table 2.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

According to the results shown in Tables 1 and 2, in the cemented carbide cutting tools 1 to 6 of the present invention, the (Ti, Ta, W) CN hard phase in the cemented carbide constituting the cemented carbide is the central part. The central portion has a relatively high concentration of W and C components, while the peripheral portion has a double structure including a peripheral portion.
A high concentration of i, Ta, and N components shows a component concentration distribution, so that the (Ti, Ta, W) CN hard phase is a single phase in both the continuous and interrupted cutting tests. It is clear that the hard cutting tools 1 to 4 exhibit more excellent wear resistance. As mentioned above,
Since the carbide cutting tool of the present invention has excellent wear resistance, it exhibits excellent cutting performance over an extremely long period of time,
It can respond satisfactorily to FA and labor saving.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 29/00-29/18

Claims (1)

(57) [Claims] 1% by volume, a binder phase consisting essentially of Co: 8 to 20%, a carbonitride hard phase of Ti, Ta and W: 10 to 35%, a tungsten carbide hard phase and unavoidable impurities: And the carbonitride hard phase is composed of a central part and a peripheral part.
In addition to having a heavy structure, the concentrations of the constituent W and C components are higher in the central portion than in the peripheral portion, while Ti,
Tungsten carbide-based cemented carbide having excellent wear resistance, characterized in that the Ta and N components are composed of a tungsten carbide-based cemented carbide having a higher component concentration distribution at the peripheral portion than at the central portion. Alloy cutting tool.