JPH11268956A - Cutting chip made of ultra-high pressure sintered material based on cubic boron nitride having excellent chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting chip made of a sintered c-BN (ultra-high pressure sintered cubic boron nitride) having excellent chipping resistance. SOLUTION: The objective c-BN-based sintered cutting chip is made of a c-BN-based material having a composition composed of 30-70 areal % of a hard dispersed phase and the remaining part of a binder phase and inevitable impurities determined by the tissue observation with an electron microscope. The hard dispersed phase is composed of c-BN having smoothed surface and the binder phase is composed of a TiN-based ceramic having a composition composed of 10-20% (areal % in the binder phase) of TiNO, 3-1% of TiB2 , 3-8% of Al2 O3 , 2-5% of AlN and the remaining part of TiN. The TiN phase constituting the continuous phase contains TiNO phase, TiB2 phase, Al2 O3 phase and AlN phase in dispersed state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cubic boron nitride based ultra-high pressure quenching which exhibits excellent chipping resistance even when high-speed cutting of difficult-to-cut materials such as hardened steel is performed at a high speed. The present invention relates to a cutting tip made of a binding material (hereinafter referred to as a c-BN based sintered cutting tip).

[0002]

2. Description of the Related Art Conventionally, as a c-BN based sintered cutting tip, as described in, for example, JP-A-53-77811, the structure of a hard dispersed phase having a surface area of 40 to 80 was observed by electron microscopy. %, Binder phase and unavoidable impurities: a composition consisting of the remainder, wherein the hard dispersed phase is composed of cubic boron nitride having a crushed surface (hereinafter, referred to as c-BN), and the binder phase is a periodic table. 4a, 5a, and 6 of
a cubic boron nitride group consisting of carbides, nitrides, borides and silicides of a group a metal, and at least one of two or more of these solid solutions, wherein the bonded phase forms a continuous phase 2. Description of the Related Art A c-BN-based sintered cutting tip composed of an ultra-high pressure sintered material (hereinafter, referred to as a c-BN-based material) is known, and it is also known that this is used for cutting steel, cast iron, and the like. ing.

[0003]

On the other hand, in recent years, high performance and high output of cutting equipment have been remarkable, and there has been a strong demand for labor saving and energy saving of cutting processing. Although there is a tendency, the above conventional c-
In the case of BN-based sintered cutting tips and other c-BN-based sintered cutting tips, when used for high-speed finishing of difficult-to-cut materials such as hardened steel, for example, toughness and insufficient strength are caused. The chipping easily occurs on the cutting blade,
Therefore, at present, the service life is reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the viewpoints described above, c- has excellent chipping resistance.
As a result of conducting research to develop a BN-based sintered cutting tip, c-BN that forms a hard dispersed phase with the c-BN-based material constituting the c-BN-based sintered cutting tip is in a pulverized surface state. The raw material powder has, for example, a smooth surface formed by performing a dipping process in an alkali melt,
Further, the ratio (area%) of the binder phase to the binder phase is as follows: titanium oxynitride (hereinafter referred to as TiNO): 10 to 20
%, Titanium boride (hereinafter referred to as TiB ₂ ): 3 to 7
%, Aluminum oxide (hereinafter referred to as Al ₂ O ₃ ): 3
８8%, aluminum nitride (hereinafter referred to as AlN): 2
-5%, titanium nitride (hereinafter referred to as TiN): The composition consisting of the remainder and the TiN phase forming a continuous phase contain T
When composed of TiN-based ceramics having a structure in which the iNO phase, TiB ₂ phase, Al ₂ O ₃ phase, and AlN phase are dispersed and distributed, the resulting c-BN based sintered cutting tip particularly forms a hard dispersed phase. Due to the action of TiNO constituting the binder phase with c-BN on the smoothened surface, while maintaining the same abrasion resistance as the above-mentioned conventional c-BN-based sintered cutting tip, the toughness is further improved. And has strength,
Therefore, even if this is used for high-speed finishing of hard-to-cut materials such as hardened steel, which requires high toughness and high strength, excellent cutting performance can be achieved without chipping of the cutting edge. The research results show that they can be used over a long period of time.

The present invention has been made based on the results of the above-mentioned research, and it has been found that a composition comprising a hard dispersed phase: 30 to 70 area%, a binder phase and unavoidable impurities: remaining, is observed by microscopic observation with an electron microscope. The hard dispersed phase is composed of c-BN having a smooth surface, and the binder phase accounts for TiNO: 10 to 20 as a percentage (area%) of the binder phase.
_{%, TiB 2: 3~7%,} Al 2 O 3: 3~8%, Al
N: 2 to 5%, TiN: remaining, and a TiN phase forming a continuous phase, including a TiNO phase and a TiB
Excellent chipping resistance c-BN made of a c-BN base material composed of TiN base ceramics having a structure in which _two phases, Al ₂ O ₃ phase and AlN phase are dispersed and distributed
It has features in the base sintered cutting tip.

Next, the reason why the composition of the c-BN base material constituting the c-BN base sintered cutting tip of the present invention is limited as described above will be described. (A) Ratio of Hard Dispersed Phase When the ratio of the hard dispersed phase is less than 30% by area, the ratio of the binder phase is relatively too large, and the excellent resistance provided by the hard c-BN constituting the hard dispersed phase is excellent. The abrasion is rapidly reduced, while the ratio is 70 area%.
On the other hand, if the ratio exceeds 2, the proportion of the binder phase becomes too small, whereby the strength and toughness are reduced, and chipping and chipping of the cutting edge are apt to occur, so that the proportion is 30 to 70 area%, preferably 40 to 65 area%. It was determined as area%. Further, c-BN which is a hard dispersed phase of the c-BN base material constituting the c-BN base sintered cutting tip of the present invention is, for example, a NaOH melt melted by heating to 350 ° C. Having a smooth surface formed by performing immersion treatment for a predetermined time in an alkali melt of TiN-based ceramics having a binding phase formed by such a smooth surface.
By the combined action with the iNO component, the c-BN base material has high strength and high toughness.

(B) Composition of Binder Phase (a) TiNO The TiNO component exists as a binder phase forming component as described above to improve the strength and toughness of the c-BN base material, and thus the smoothness of c-BN. Has an effect of significantly improving the chipping resistance of the cutting insert in combination with the surface, but if the content is less than 10 area%, the desired effect cannot be obtained in the above-mentioned action, while the content exceeds 20 area%. When,
Since the hardness of the binder phase itself decreases and causes a decrease in wear resistance, the content ratio is set to 10 to 20 area%, preferably 12 to 17 area%.

(B) TiB _{2 The} TiB ₂ component has the effect of improving the hardness of the binder phase itself and thereby contributing to the improvement of the wear resistance of the cutting tip.
If the content is less than 3 area%, the desired effect of improving wear resistance cannot be obtained, while if the content exceeds 7 area%, the binder phase itself becomes brittle and chipping or chipping of the cutting edge is liable to occur. Therefore, the content ratio was determined to be 3 to 7 area%.

(C) Al ₂ O _{3 The} Al ₂ O ₃ component has an effect of improving the welding resistance and heat resistance of the binder phase and thereby contributing to the improvement of the wear resistance of the cutting edge. Is less than 3 area%, a desired improvement effect cannot be obtained in the above operation, while the content ratio is 8 area%.
If the ratio exceeds 3, the strength and toughness of the binder phase decrease, and chipping easily occurs on the cutting edge. Therefore, the content ratio is set to 3 to 8 area%.

(D) AlN The AlN component has the effect of improving the heat resistance and the heat-resistant plastic deformation of the binder phase and thereby suppressing the uneven wear of the cutting edge. If the desired improvement effect cannot be obtained in the action, and if the content ratio exceeds 5% by area, the binder phase itself becomes brittle and chipping or chipping easily occurs in the cutting edge. It was determined as 5 area%.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As a raw material powder, c-BN powder which has been subjected to a dipping treatment in a NaOH melt heated to 350 ° C. and melted for a predetermined time within a range of 5 to 15 minutes to obtain a smooth surface, C-BN powder on the pulverized surface without performing the immersion treatment,
TiN powder, TiAl ₃ powder, TiAl powder, TiAl powder each having a predetermined average particle size in the range of 0.5 to 2 μm.
₂ Al powder, TiNO powder, and Al ₂ O ₃ powder were prepared, and these raw material powders were blended to a predetermined composition, wet-mixed in a ball mill for 72 hours, dried, and then dried.
mm × thickness: Press-molded into a compact having a size of 1.5 mm, and heat-treated this compact in vacuum at a predetermined temperature in the range of 900 to 1300 ° C. for 1 hour. This was superposed on a cemented carbide chip (composition: WC-9 wt% Co) having a size of diameter: 20 mm × thickness: 2.0 mm and charged into an ultra-high pressure sintering apparatus, and 1200
Sintering at a predetermined temperature within the range of ~ 1400 ° C under a pressure of 5 GPa for 1 hour, and after sintering, grinding the upper and lower surfaces using a diamond grindstone and dividing into four by wire cutting by arc discharge. And the comparative c-BN based sintered cutting tips (hereinafter referred to as comparative cutting tips) 1 to 11 and the comparative c-BN based sintered cutting tips (hereinafter referred to as comparative cutting tips) backed by the cemented carbide described above. ) 1 to 3 were each manufactured. In addition, the comparative cutting tip 1 is a raw material powder c
-BN powder was not subjected to immersion treatment with an alkali melt, but was manufactured using c-BN powder in a pulverized state, and the comparative cutting tip 2 contained TiNO in the binder phase.
Containing no component, and comparative cutting tip 3
Is manufactured using c-BN powder on the crushed surface as a raw material powder and not containing a TiNO component.

For each of the resulting c-BN base materials constituting the various cutting tips, an X-ray diffractometer, a scanning electron microscope, a scanning Auger electron spectrometer,
And forming a hard dispersed phase using an image analyzer.
The BN content ratio, average particle size, and surface properties, as well as the composition and structure of the binder phase were observed and measured. The results of these observations and measurements are shown in Table 1. Although not shown in Table 1, any of the cutting inserts has c-B
The binder phase of the N-based material is in a TiN phase forming a continuous phase,
TiNO phase, TiB ₂ phase, Al ₂ O ₃ phase, and AlN
The phase had a structure in which the phases were dispersed and distributed.

Further, these cutting tips are brazed to a cutting step formed at the tip of a cutting edge of a cemented carbide body (composition: WC-10% by weight Co) to obtain a JIS.
A throw-away type cutting tool having the shape specified in TNMA160408 is used, and the work material is carburized hardened steel (SC
M420, round bar hardness H _R C62), Cutting speed: 350 meters / min, cut: 0.2 mm, Feed: 0.15 mm / rev, Cutting time: Wet fast finishing cutting difficult-to-cut materials at 30 minutes, the condition A test was performed to measure the flank wear width of the cutting blade. The measurement results are shown in Table 1.

[0014]

[Table 1]

[0015]

According to the results shown in Table 1, the cutting tips 1 to 11 of the present invention do not generate chipping on the cutting edge even when performing high-speed finish cutting of carburized and hardened steel, which is a difficult-to-cut material. While excellent wear resistance is exhibited, the c-BN constituting the hard dispersed phase has a pulverized surface or a TiNO component in the binder phase as shown in Comparative Cutting Tips 1 to 3. It is clear that chipping occurs on the cutting edge when no is contained, which results in a relatively short service life. As described above, the c-B of the present invention
The N-base sintered cutting tip is composed of c-BN which forms a hard dispersed phase.
Because of the smooth surface and the effect of the TiNO component of the binder phase, it has much higher strength and toughness compared to the conventional c-BN based sintered cutting tip, so high strength and high toughness are required. For example, even when used for high-speed finish cutting of hard-to-cut materials such as hardened steel, excellent cutting performance is exhibited for a long time without chipping of the cutting edge.

Claims (1)

[Claims] 1. Structure observation by an electron microscope shows a composition comprising a hard dispersed phase: 30 to 70 area%, a binder phase and an unavoidable impurity: remaining, and wherein the hard dispersed phase has a smoothed surface. The above-mentioned binder phase is a ratio (area%) of the binder phase to titanium oxynitride: 10 to 20%, titanium boride: 3 to 7%, aluminum oxide: 3 to 8%, aluminum nitride: 2 ５5%, titanium nitride: remaining, having a composition consisting of: and a structure in which a titanium oxynitride phase, a titanium boride phase, an aluminum oxide phase, and an aluminum nitride phase are dispersed and distributed in a titanium nitride phase forming a continuous phase. Made of cubic boron nitride based ultra-high pressure sintered material composed of titanium nitride based ceramics and characterized by excellent chipping resistance cubic boron nitride based ultra high pressure sintered material Cutting chip.