JP3319213B2 - Cermet cutting tool with excellent fracture resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is applicable to, for example, high-speed cutting of steel without cutting or chipping (small chipping) of a cutting edge in continuous cutting as well as in intermittent cutting. The present invention relates to a cermet cutting tool exhibiting improved fracture resistance.

[0002]

2. Description of the Related Art Conventionally, as a cermet cutting tool, for example, as described in JP-A-6-256888, a binder phase containing Co and / or Ni as a main component: 5
(A) a hard phase having a single-phase structure composed of titanium carbonitride (hereinafter, referred to as TiCN) (hereinafter, referred to as a single-phase hard phase), (B) Composite carbonitride of Ti and one or more of Ta, Nb, Zr, W, and Mo (hereinafter, (Ti, M)
CN) and a cored double phase structure and / or
A cermet cutting tool comprising a hard phase having a cored triple phase structure (hereinafter, referred to as a cored hard phase) and a cermet having a composition consisting of the above (a) and (b) is known, It is also known that this is used, for example, for continuous cutting and interrupted cutting of steel.

[0003]

On the other hand, in recent years, high performance, high output, and high precision of a cutting apparatus have been remarkable, and accordingly, cutting processing has tended to be accelerated. Conventional cermet cutting tools and many other cermet cutting tools, when used for high-speed cutting of steel, for example, do not cause any problems in continuous cutting, but in intermittent cutting, chipping and At present, chipping or the like easily occurs, and the service life is reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above point of view, focusing on the above-mentioned conventional cermet cutting tool, as a result of conducting research to develop a cermet cutting tool with more excellent fracture resistance compared to this,
The above-mentioned conventional cermet cutting tool is disclosed in JP-A-6-256.
As described in No. 884, page 3, column 4, sintering can be performed, for example, by performing the process of raising the temperature from room temperature to 1100 ° C.
A nitrogen atmosphere of 0 ^-2 torr is set,
Heating process up to a predetermined sintering temperature in the range of 1600 ° C.
The process of holding the sintering temperature for 1 hour and the process of cooling from the end of holding the sintering temperature to room temperature were performed in a nitrogen atmosphere of 100 torr, and the rate of temperature rise was 3 ° C / min and the cooling rate was 5 ° C / mi
The hard phase constituting the cermet is specified to be (Ti, W, Ta) CN or (Ti, W, Ta, Nb and / or Mo) CN. Then, the sintering is started in a vacuum or an inert gas atmosphere at a rate of 20 ° C./min or less from normal temperature at a rate of at most 20 ° C./min. The temperature is raised from the liquid phase appearance temperature to the sintering temperature at a rate of 20 ° C./min or less,
The holding time at the sintering temperature is 1 hour or more, the cooling from the sintering temperature to at least 1150 ° C. is performed at a rate of 70 ° C./min or more, and the subsequent cooling rate to normal temperature is 2
0 ° C./min or less ”, substantially, titanium nitride (hereinafter referred to as TiN), TiCN, (Ti,
A single-phase hard phase composed of at least one of W, Ta) CN and (Ti, W, Ta, Nb and / or Mo) CN, and (Ti, W, Ta) CN or (Ti, W) ,
The cored hard phase comprises a cored hard phase composed of Ta, Nb and / or Mo) CN, and a binder phase containing Co and / or Ni as a main component. _{(Ti 1- (a + b)} W a Ta b) m (C 1-x n x) n, (Ti 1- (a + b + c) W a Ta b Nb c) m (C 1-x n _{x) n, (Ti 1- (} a + b + d) W a Ta b Mo d) m (C 1-x n x) n, (Ti 1- (a + b + c + d) W a Ta b _{nb c Mo d) m (C} 1-x n x) n, in case of expressed respectively, a: 0.02~0.2, b: 0.02~0.2 , c: 0.005~0. 15, d: 0.005 to 0.15, x: 0.1 to 0.6, n / m: 0.8 to 1.2, and dislocation exists in the cored structure hard phase. Cermets are formed, and the resulting cermet-formed cutting tool is Research results have shown that, not only cutting but also intermittent cutting can be performed at high speed, and the cutting edge exhibits excellent chipping resistance without chipping or chipping.

[0005] The present invention has been made based on the above research results, and is based on TiN, TiCN,
(Ti, W, Ta) CN, (Ti, W, Ta, Nb) C
N, (Ti, W, Ta, Mo) CN, and (Ti,
W, Ta, Nb, Mo) Single-phase hard phase composed of one or more of CN: 3 to 50%, (Ti, W, Ta) C
N, (Ti, W, Ta, Nb) CN, (Ti, W, T
a, Mo) CN, or (Ti, W, Ta, Nb, M)
o) Core-structured hard phase composed of CN: 40 to 95%, Co
And binder phase and inevitable impurities as a main component / or Ni: remainder has a composition consisting of, the cored structure hard phase, respectively _{formula: (Ti 1- (a + b} ) W a Ta b) _{m (C 1-x n x} ) n, (Ti 1- (a + b + c) W a Ta b Nb c) m (C 1-x n x) n, (Ti 1- (a + b + d _{) W a Ta b Mo d)} m (C 1-x n x) n, (Ti 1- (a + b + c + d) W a Ta b Nb c Mo d) m (C 1-x n x) _When represented by _n and, a: 0.02 to 0.2, b: 0.02 to 0.2, c: 0.005 to 0.15, d: 0.005 to 0.15, x: 0 0.1 to 0.6, n / m: 0.8 to 1.2, and further comprising a cermet having dislocations in the cored hard phase, and having excellent fracture resistance. It has features in the cutting tool.

Next, the reason why the composition of the cermet constituting the cermet cutting tool of the present invention is limited as described above will be described. (1) Single-Phase Hard Phase The single-phase hard phase has an effect of improving the high-temperature wear resistance. However, if the ratio is less than 3% by volume, the desired effect cannot be obtained in the above-mentioned operation. If the content exceeds% by volume, the ratio of the binder phase becomes relatively too small and the toughness is reduced. Therefore, the ratio is set to 3 to 50% by volume, preferably 5 to 30% by volume.

(2) Cored structure hard phase The cored structure hard phase composed of the core portion and the peripheral ring portion has an effect of improving fracture resistance without deteriorating wear resistance, and further has an outer periphery of the core portion. The number of dislocations present along the part or the number of dislocations present irregularly in the core has the effect of further improving the fracture resistance. If the ratio is less than 40% by volume, the desired effect is not obtained. On the other hand, if the ratio exceeds 95% by volume, the abrasion resistance is reduced. Therefore, the ratio is set to 40 to 95% by volume, preferably 60 to 85% by volume.

Further, in the composition formula representing the cored structure hard phase, the atomic ratios of the constituent components are limited as described above for the following reasons. (A) W (a) The W component constituting the cored hard phase has an effect of suppressing grain growth of the hard phase itself and thereby improving toughness.
If the ratio is less than 0.02, the desired effect cannot be obtained, while if the ratio is more than 0.2, the wear resistance of the hard phase itself is reduced. 02 to 0.2, preferably 0.05 to 0.15.

(B) Ta (b) Similarly, the Ta component not only improves the plastic deformation resistance of the hard phase itself, but also acts as a solid solution to increase the lattice constant indispensable for dislocation generation. But the ratio is 0.0
If the ratio is less than 2, the desired effect cannot be obtained, while if the ratio exceeds 0.2, the wear resistance is reduced.
The ratio is 0.02-0.2, preferably 0.05-
It was set to 0.15.

(C) Nb (c) The Nb component has an effect of improving the heat resistance of the hard phase, and therefore is contained as necessary.
If the ratio is less than 5, the desired effect of improving heat resistance cannot be obtained, while if the ratio exceeds 0.15, the wear resistance of the hard phase deteriorates.
5, desirably 0.05 to 0.1.

(D) Mo (d) The Mo component improves the wettability between the hard phase and the binder phase,
Therefore, the cermet has an effect of improving the strength of the cermet.
If the content is less than 0.15, the desired effect cannot be obtained. If the content exceeds 0.15, molybdenum carbide (Mo ₂ C) is formed as a hard phase, and the fracture resistance is reduced. The ratio was set to 0.005 to 0.15, preferably 0.05 to 0.1.

(E) N (x) If the ratio of the N component is less than 0.1, the ratio of the C component relatively exceeds 0.9 and becomes too large, and the desired toughness is secured in the hard phase. But the ratio is 0.6
Exceeds, the ratio of the C component is less than 0.4,
Since the wear resistance of the hard phase decreases, the ratio is set to 0.1 to 0.6, preferably 0.3 to 0.5.

(F) n / m If the ratio is less than 0.8 or exceeds 1.2, vacancies will be present in the lattice of the hard phase, and a decrease in the strength of the hard phase is inevitable. From 0.8 to 1.2,
Desirably, it is set to 0.9 to 1.1. Further, in the hard phase having a cored structure of the cermet constituting the cutting tool of the present invention, even if impurities such as Zr, Hf, V, and Cr are contained in a solid solution, the content affects the occurrence of dislocation. There is no problem if the amount is small enough not to affect

[0014]

Next, the cermet cutting tool of the present invention will be described in detail with reference to examples. TiC having an average particle size in the range of 0.5 to 2 μm as a raw material powder
Powder, TiN powder, WC powder, Mo ₂ C powder, TaC powder, NbC powder, TiCN powder (TiC / TiN = 50/50 by weight ratio), (Ti, W) CN
Powder (TiC / TiN / WC = 35/35/30),
(Ti, W, Mo) CN powder (TiC / TiN / WC /
Mo ₂ C = 30/30/30/10), (Ti, Ta)
CN powder (TiC / TiN / TaC = 35/35/3
0), (Ta, Nb) C powder (TaC / NbC = 90 /
10), Co powder, and Ni powder were prepared, and these raw material powders were blended to have the composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and then 1.5 ton / cm ^2.
Press molding into a green compact at a pressure of
In a nitrogen atmosphere of rr, from room temperature to 1150 ° C, 5-20
The temperature is raised at a desired rate in the range of 1 ° C./min, and the temperature is raised from 1150 ° C. to the liquid phase appearance temperature at a predetermined rate in the range of 50 to 100 ° C./min.
Up to a predetermined sintering temperature within the range of 00 ° C, 5-20 ° C / mi
The temperature is raised at a predetermined rate within the range of n and maintained at the predetermined sintering temperature for 1 hour.
Cool at a predetermined rate within the range of min.
Sintering under the condition of cooling at a predetermined rate within the range of 5 to 20 ° C./min.
Cermet cutting tools of the present invention (hereinafter, referred to as cutting tools of the present invention) 1 to 15 each having a throwaway tip shape conforming to the standard of G432 were manufactured.

For the purpose of comparison, as shown in Table 2, the composition was the same for each of the cutting tools 4, 6 and 15 of the present invention as shown in Table 1, and the sintering was carried out from room temperature to 1 point.
The temperature raising process up to 150 ° C. is a nitrogen atmosphere of 10 ⁻² torr, the temperature raising process from 1150 ° C. to a predetermined sintering temperature in the range of 1400 to 1600 ° C., the holding process at the sintering temperature for 1 hour, In addition, the cooling process from the end of holding the sintering temperature to the room temperature was performed in a nitrogen atmosphere of 100 torr, and the temperature rising rate was 3
C / min, and a cooling rate of 5 ° C./min.
Conventionally called cutting tools) 1 to 3 were manufactured respectively.

[0016] Next, the various cutting tools obtained as a result are subjected to image analysis of microstructure photographs of the cermets constituting the cutting tools by a scanning electron microscope, whereby a single-phase hard phase, a cored-structure hard phase, and a binding phase are obtained. Was measured.
The measurement results are shown in Tables 3 and 4. Further, a specimen having a size of 3 mm in diameter and 50 μm in thickness was cut out from the center of each of the above cutting tools, and the polished surface thereof was subjected to an ion thinning treatment. ,
The hard phase having a cored structure present in an arbitrary area of 10 μm × 10 μm was observed, and the presence or absence of dislocation was observed at a magnification of 60,000. The results are shown in Tables 5 and 6. Also, FIG.
3 shows the microstructure of the cored hard phase (60,000 times) observed in the inventive cutting tools 6 (FIG. 1), 14 (FIG. 2), and 5 (FIG. 3), respectively. Furthermore, the polished surface of the specimen cut out from the central part of each of the above-mentioned various cutting tools was observed using a scanning Auger electron spectrometer, and the constituent components of any hard phase having a cored structure were quantitatively analyzed. The results are shown in Tables 5 and 6.

Further, the above-mentioned various cutting tools, work material: SNCM439 (Hardness: H _B 270) round bar, Cutting speed:. 250 meters / min, cut: 2 mm, Feed: 0.3 mm / rev,. cutting time: 20 min, dry high-speed continuous cutting test of steel in the conditions, as well as work material: SNCM439 (hardness: H _B 270) in the length direction at equal intervals of four longitudinal grooves containing round bar, cutting speed: A dry high-speed intermittent cutting test of steel was performed under the conditions of 250 m / min., Depth of cut: 2.5 mm, feed: 0.2 mm / rev., Cutting time: 5 minutes, and the flank wear width of the cutting edge was measured. . Table 7 shows the results.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6]

[0024]

[Table 7]

[0025]

From the results shown in Tables 1 to 7, the cutting tools 1 to 15 of the present invention show excellent wear resistance not only in high-speed continuous cutting but also in high-speed intermittent cutting. Conventional cutting tools 1 to 3 which have substantially no dislocation in the cored structure hard phase show the same excellent wear resistance in high-speed continuous cutting, but chipping or chipping of the cutting edge occurs in high-speed interrupted cutting However, it is clear that the service life is reached in a relatively short time. As described above, the cermet cutting tool of the present invention exhibits excellent fracture resistance to continuous cutting and intermittent cutting at high speed, so that it can sufficiently cope with recent remarkable cutting equipment, It demonstrates excellent performance.

[Brief description of the drawings]

FIG. 1 is a microscopic structural view (magnification: 60,000 times) of a cored structure hard phase of a cutting tool 6 of the present invention as viewed with a transmission electron microscope.

FIG. 2 is a microscopic structural view (magnification: 60,000 times) of the cored hard phase of the cutting tool 14 of the present invention as viewed with a transmission electron microscope.

FIG. 3 is a microscopic structural view (magnification: 60,000 times) of the cored structure hard phase of the cutting tool 5 of the present invention viewed with a transmission electron microscope.

Continuation of the front page (56) References JP-A-6-248385 (JP, A) JP-A-5-75776 (JP, A) JP-A-4-231467 (JP, A) JP-A-4-13841 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B23B 27/14 B23P 15/28 C22C 29/04

Claims (4)

(57) [Claims] 1. Titanium nitride, titanium carbonitride, and Ti
Single-phase hard phase composed of at least one of carbon and nitride composites of W and Ta: 3 to 50% by volume, hard phase having a cored structure: 40 to 95% by volume, mainly containing Co and / or Ni And a hard phase having a cored structure is composed of a composite carbonitride of Ti, W and Ta, and is represented by a composition formula: (Ti _{1- (a + b) W a Ta b)} m ( when expressed in _{C 1-x n x) n} , in atomic ratio, a: 0.02~0.2, b: 0.02~0.2 , x: 0 0.1 to 0.6, n / m: 0.8 to 1.2, and the cored structure hard phase is composed of a cermet having dislocations. Excellent cermet cutting tool. 2. Titanium nitride, titanium carbonitride, and Ti
Single phase hard phase composed of one or more of composite carbonitrides of W, Ta, and Nb: 3 to 50% by volume, cored structure hard phase: 40 to 95% by volume, Co and / or Ni A binder phase having a main component and an unavoidable impurity having the following composition: The cored hard phase is composed of a composite carbonitride of Ti, W, Ta, and Nb, and is represented by a composition formula: (Ti _{1- (a + b + c)} if expressed in _{W a Ta b Nb c) m} (C 1-x n x) n, in atomic ratio, a: 0.02~0.2, b: 0.02 -0.2, c: 0.005-0.15, x: 0.1-0.6, n / m: 0.8-1.2, and the cored structure hard phase Is a cutting tool made of cermet with excellent fracture resistance, which is made of cermet having dislocations. 3. Titanium nitride, titanium carbonitride, and Ti
Single-phase hard phase composed of at least one of carbon nitrides of W, Ta, and Mo: 3 to 50% by volume, cored structure hard phase: 40 to 95% by volume, Co and / or Ni A binder phase having a main component and an unavoidable impurity: having the composition of the remainder, and the cored structure hard phase is composed of a composite carbonitride of Ti, W, Ta, and Mo, and has a composition formula: (Ti _{1- (a + b + d)} when expressed in _{W a Ta b Mo d) m} (C 1-x n x) n, in atomic ratio, a: 0.02~0.2, b: 0.02 ~ 0.2, d: 0.005 to 0.15, x: 0.1 to 0.6, n / m: 0.8 to 1.2, and the cored structure hard phase Is a cutting tool made of cermet with excellent fracture resistance, which is made of cermet having dislocations. 4. Titanium nitride, titanium carbonitride, and Ti
Single-phase hard phase composed of one or more of composite carbonitrides of W, Ta, Nb and Mo: 3 to 50% by volume, hard phase having a cored structure: 40 to 95% by volume, Co and / or A binder phase having Ni as a main component and an unavoidable impurity: a balance, and the cored structure hard phase is composed of a composite carbonitride of Ti, W, Ta, Nb, and Mo. _{formula: (Ti 1- (a + b} + c + d) W a Ta b Nb c Mo d) m when represented by _{(C 1-x n x)} n, in atomic ratio, a: from .02 to 0 0.2, b: 0.02 to 0.2, c: 0.005 to 0.15, d: 0.005 to 0.15, x: 0.1 to 0.6, n / m: 0.8 A cutting tool made of cermet having excellent fracture resistance, wherein the cutting tool satisfies the following (1) to (2), and the cored structure hard phase is formed of a cermet having dislocations.