JP2003176177A - Cutting tip made of high pressure sintered cubic boron nitride having excellent chipping resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tip made of high pressure sintered cubic boron nitride which has excellent chipping resistance. <P>SOLUTION: The cutting tip consists of the high pressure sintered cubic boron nitride compact made by a press molding, which has a three phase structure consisting of a continuous phase, a hard dispersion phase and an intermediate adhesion phase lying between the continuous phase and the hard dispersion phase by structural observation with a scanning electron microscope, and has a blended composition consisting of, as the continuous phase forming components, by mass, 15 to 56% of two or more kinds selected from titanium nitride, titanium carbonitride and titanium carbide or titanium carbonitride, and as the intermediate adhesion phase forming components, 2 to 10% compound nitride of Ti and Al and 2 to 10% tungsten carbide, and the balance (40 to 65%) cubic boron nitride as the hard dispersion phase forming components. <P>COPYRIGHT: (C)2003,JPO

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 ultrahigh pressure which exhibits excellent chipping resistance even when high-hardness hardened steel and other difficult-to-cut materials are subjected to finish cutting at high speed. Cutting tip made of sintered material (hereinafter, c-BN
It is referred to as a base sintered cutting tip).

[0002]

2. Description of the Related Art Conventionally, as a c-BN based sintered cutting tip, as described in, for example, Japanese Patent Laid-Open No. 53-77811, a substantially continuous bonded phase is observed by observing a structure with a scanning electron microscope. And a two-phase structure of a hard dispersed phase,
In addition, titanium nitride (hereinafter referred to as TiN) and titanium carbonitride (hereinafter referred to as T
iCN), and one or more of titanium carbide (hereinafter, TiC): 20 to 45%, as the hard dispersed phase forming component, cubic boron nitride (hereinafter,
c-BN): c, which is composed of a cubic boron nitride-based ultra-high pressure sintered material (hereinafter referred to as a c-BN-based material), which is a sintered body of a press-molded body having a compounding composition of
A BN-based sintered cutting tip is known, and it is also known that it is used for surface finishing cutting of various steels and cast irons, for example.

[0003]

On the other hand, in recent years, cutting equipment has been remarkably improved in performance and output, and there is also a strong demand for labor saving and energy saving in the cutting work. Although there is a tendency, the above-mentioned conventional c-
BN-based sintered cutting chips and other c-BN-based sintered cutting chips form a continuous bonded phase when used for high-speed finish cutting of hard-to-cut materials such as high hardness hardened steel. The c-BN phase, which is a hard disperse phase substantially to the TiCN phase, is insufficient due to insufficient adhesion.
The N phase is easily peeled off, and as a result, chipping (fine chipping) is generated on the cutting edge, and it is the current situation that the useful life is reached in a relatively short time.

[0004]

Therefore, the present inventors have
From the above viewpoint, c- which has excellent chipping resistance
As a result of research to develop a BN-based sintered cutting tip, when manufacturing a c-BN-based sintered cutting tip, c-BN powder and TiN powder, which are used as raw material powders,
In addition to TiCN powder and TiCN powder,
A composite nitride of i and Al [hereinafter referred to as (Ti, Al) N] powder and tungsten carbide (hereinafter referred to as WC) powder were used as raw material powders, and these were used in mass% (hereinafter,% means mass%). 2) or more of TiN, TiCN, and TiC, or TiCN: 15 to 56%, (Ti, Al) N: 2 to 10%, WC: 2 to 10%, c-BN: rest ( However, when a press-molded product formed by mixing and mixing is mixed with a compounding composition of 40 to 65%), (Ti, A
l) N powder and WC powder preferentially aggregate on the surface of c-BN powder during sintering and react to form a reaction product, and in the c-BN based material after sintering, the reaction product Intervenes between the continuous binder phase consisting essentially of the TiCN phase and the hard disperse phase consisting of the c-BN phase, and the reaction product is the TiCN phase constituting the continuous binder phase, and the hard dispersion phase. The c-BN-based sintered cutting tip made of this c-BN-based material has, for example, a high hardness because it adheres extremely strongly to any of the c-BN phases constituting the phase and acts as an intermediate adhesion phase. Even when it is used for high-speed finish cutting of hard-to-cut materials such as hardened steel, the cutting edge is c-B
The research results show that chipping does not occur due to insufficient N-phase adhesion and excellent cutting performance is exhibited over a long period of time.

The present invention has been made on the basis of the above-mentioned research results, and it has been confirmed by a scanning electron microscope that the structure is substantially continuous bonded phase, hard dispersed phase, and the continuous bonded phase and hard dispersed phase. Showing a three-phase structure of an intermediate close contact phase interposed between the two, two or more kinds of TiN, TiCN, and TiC as the above continuous binder phase forming component, or TiCN: 15 to 56%, the above intermediate close contact phase forming component (Ti, Al) N: 2 to 10%, WC: 2 to 10%, and as the hard dispersed phase forming component, c-BN: the rest (however, 40 to 65% contained). C-B, which is a sintered compact of a press molded body
Excellent chipping resistance c composed of N-based material
-Features a BN-based sintered cutting tip.

Next, the reason why the composition of the c-BN-based material constituting the c-BN-based sintered cutting tip of the present invention is limited as described above will be explained. (A) TiN, TiCN, and TiC These components have the effects of improving the sinterability and forming a continuous bonded phase consisting essentially of the TiCN phase to improve the strength. If it is less than 15%, the desired strength cannot be ensured. On the other hand, if the blending ratio exceeds 56%, the wear resistance is sharply reduced. Therefore, the blending ratio is set to 15 to 56%. . It is preferably 30 to 50%.

(B) (Ti, Al) N and WC As described above, these components are preferentially c-B during sintering.
Agglomerates on the surface of N powder and reacts to form a reaction product,
The c-BN based material after sintering, TiCN of the continuous binder phase
Phase and the c-BN phase of the hard dispersed phase. Moreover, this reaction product is the T of the continuous bonded phase.
Since the iCN phase and the c-BN phase of the hard dispersed phase have a property of firmly adhering and joining,
The adhesion of the TiCN phase to the TiCN phase, which is a continuous binder phase, is remarkably improved, and as a result, the chipping resistance of the cutting edge is improved, but the mixing ratio of any of these components is out of the above range. However, it is not possible to secure strong adhesion between the hard dispersed phase and the continuous binding phase as an intermediate adhesion phase, and therefore (Ti, Al) N and WC
The above-mentioned mixing ratio of is determined empirically in order to secure strong adhesion. Desirably 3 to 3 each
8% is recommended.

(C) c-BN c-BN which constitutes the hard dispersed phase is extremely hard, which improves wear resistance. However, if the compounding ratio is less than 40%, the desired excellent wear resistance is obtained. However, if the compounding ratio exceeds 65%, c
-Since the BN-based material itself has reduced sinterability, and as a result, chipping is likely to occur at the cutting edge, the ratio is 44-
It was set at 65%. It is desirable to set it to 45 to 60%. The c-BN-based sintered cutting tip of the present invention described above has titanium nitride (hereinafter referred to as TiN) having a golden color tone on its surface as a discrimination layer before and after using the cutting tip.
The layer may be formed by vapor deposition. In this case, if the average layer thickness is less than 0.5 μm, it is not possible to impart a golden color tone sufficient for identification, while the identification is up to 5 μm. Since the thickness is sufficient, the average layer thickness may be 0.5 to 5 μm.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the c-BN-based sintered cutting tip of the present invention will be specifically described with reference to Examples. As raw material powders, TiN powder and TiCN powder for forming a continuous binder phase, each having a predetermined average particle size within the range of 0.5 to 2 μm, further TiC powder, WC powder for forming an intermediate adhesion phase, And (Ti, Al) N powder, ( _{Ti 0.65} Al _0.35 ) N powder, (Ti _0.50 Al _0.50 ).
N powder, and (indicating numbers atomic ratio of either the _{formula) (Ti 0.35 Al 0. 65)} N powder, further providing a c-BN powder as a hard dispersed phase forming, Table these raw powders 1 and 7 in a ball mill.
After wet-mixing for 2 hours and drying, it is press-molded at a pressure of 100 MPa into a compact having a dimension of diameter: 50 mm x thickness: 1.5 mm, and the compact is 900- 1 for a given temperature within the range of 1300 ° C
Pre-sintered under the condition of holding time, and then super-high pressure in a state where it was superposed with a cemented carbide chip (composition: WC-8% Co) having dimensions of diameter: 50 mm x thickness: 2 mm prepared separately. It is charged into a sintering machine, sintered at a predetermined temperature within the range of 1200 to 1400 ° C. under a pressure of 5 GPa for 30 minutes, and after sintering, the upper and lower surfaces are ground with a diamond grindstone and arc-discharged. 1 to 1 of the present invention c-BN-based sintered cutting tip (hereinafter referred to as the present cutting tip) lined with the above-mentioned cemented carbide by sizing by wire cutting according to
2 and comparative c-BN based sintered cutting chips (hereinafter referred to as comparative cutting chips) 1 to 12 were manufactured. In addition,
Each of the comparative cutting tips 1 to 12 has a compounding composition in which the compounding ratio of any of the (Ti, Al) N powder and the WC powder, which are the components forming the intermediate contact phase, is out of the range of the present invention. . In addition, the cutting tip 11 of the present invention and the comparative cutting tip 11 were ultrasonically cleaned in acetone and dried, and then mounted in a normal arc ion plating apparatus, and metal Ti was used as a cathode electrode (evaporation source). First, exhaust the inside of the device to 0.5P
While maintaining a vacuum of a
After heating to 0 ° C., a DC bias voltage of −1000 V was applied to the cutting tip, while a current of 100 A was passed between the metal Ti of the cathode electrode and the anode electrode to generate an arc discharge. T the cutting tip surface
i-Bombart cleaning, and then nitrogen gas was introduced into the apparatus as a reaction gas to make a reaction atmosphere of 5 Pa, and a DC bias voltage of -100 V was applied to the cutting tip, while a cathode electrode and an anode electrode were applied. Is 10
A current of 0 A is applied to generate arc discharge, and a TiN layer having an average layer thickness of 1.5 μm and a golden color tone is formed on the surfaces of the cutting tip 11 of the present invention and the comparative cutting tip 11 by vapor deposition. did.

The structure of each of the c-BN base materials constituting the various cutting tips obtained as a result was observed with a scanning electron microscope, and it was found that all the cutting tips had a substantially continuous bonding phase. , A hard disperse phase, and an intermediate cohesive phase interposed between the continuous binder phase and the hard disperse phase.

Further, these cutting tips are brazed to the notch step formed at the tip of the cutting edge of the cemented carbide body (composition: WC-10% Co) to JIS TN.
For the cutting inserts 1 to 4 of the present invention and the comparative cutting inserts 1 to 4, a slow-away type cutting tool having a shape specified in MA160408 is used. Work material: carburized and hardened steel (JIS SCM415, hardness: HRC62) Round bar, cutting speed: 350 m / min, depth of cut: 0.15 mm, feed: 0.1 mm / rev, cutting time: 30 minutes, dry high-speed continuous turning cutting test of difficult-to-cut materials, and cutting according to the present invention About the chips 5-8 and the comparative cutting chips 5-8, the work material: carburized and hardened steel (JIS SCM415, hardness: HRC62) four longitudinally equidistant round bars, cutting speed: 300 m / Min, depth of cut: 0.15 mm, feed: 0.2 mm / rev, cutting time: 60 minutes, dry high-speed intermittent surface finish cutting test for difficult-to-cut materials,
Further, regarding the present cutting tips 9 to 12 and the comparative cutting tips 9 to 12, work material: spheroidal graphite cast iron (JIS / FCD70), cutting speed: 450 m / min, depth of cut: 0.15 mm, feed: 0.2 mm / Rev, cutting time: 30 minutes, a dry high-speed continuous surface finishing cutting test was performed on difficult-to-cut materials, and the flank wear width of the cutting edge was measured in each cutting test. The measurement results are shown in Tables 1 and 2. In addition, when the TiN layer having a golden color tone was vapor-deposited and formed on the surface of the cutting tip as a discrimination layer before and after using the cutting tip, the surface after the cutting test was observed, and it was found that the rake face of the cutting edge portion was obtained. The chip contact portion of the flank, as well as the TiN layer at the cutting edge ridge portion where the rake face and the flank intersect, the TiN layer is abraded, and the gray color of the cutting chip base material is exposed, It was possible to easily identify before and after use from the contrast between the golden color of the portion other than the worn portion of the TiN layer and the gray color of the cutting chip base material.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

From the results shown in Tables 1 and 2, the cutting chips 1 to 12 of the present invention can be used as cutting edges even when carburizing and quenching steel, which is a difficult-to-cut material, is turned or surface-finished at high speed. It shows excellent wear resistance without chipping and exhibits excellent cutting performance over a long period of time, while Ti- which is an intermediate adhesion phase forming component as shown in Comparative Cutting Tips 1-12. Even if the compounding ratio of any one of the Al compound powder and the WC powder deviates from the range of the present invention, chipping of the cutting edge occurs, and it is apparent that this leads to a relatively short service life. As described above, in the c-BN-based sintered cutting tip of the present invention, the c-BN phase constituting the hard dispersed phase is extremely strongly bonded to the TiCN phase constituting the continuous bonded phase due to the interposition of the intermediate cohesive phase. It adheres closely and, of course, it exhibits excellent chipping resistance in high-speed cutting and high-speed surface finishing cutting of difficult-to-cut materials such as high hardness hardened steel as well as cutting under normal conditions. It can fully satisfy the needs for higher performance and higher output of cutting equipment, as well as labor saving and energy saving of cutting processing.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C04B 35/58 101 C04B 41/87 N 41/87 C23C 14/06 A C04B 35/58 103H C23C 14/06 35/56 S (72) Inventor Seki Nakata 1002-14 Mukayama, Naka-machi, Naka-gun, Ibaraki Prefecture Mitsubishi Material Co., Ltd. Naka Research Center, R & D Center (72) Inventor Kazuo Yamamoto 1002-Mukayama, Naka-machi, Naka-gun, Ibaraki Prefecture 14 Mitsubishi Material Co., Ltd. Central Research Laboratory Naka Research Center F-term (reference) 3C046 FF03 FF10 FF19 FF25 FF32 FF40 4G001 BA25 BA31 BA34 BA38 BA57 BA61 BB25 BB31 BB34 BB38 BB57 BB61 BC72 BD12 BD18 BE01 4K029 A05 CA06 DD EA01 FA04 FA05

Claims (2)

[Claims] 1. A three-phase microstructure consisting of a continuous binder phase, a hard disperse phase, and an intermediate close contact phase interposed between the continuous binder phase and the hard disperse phase, which is obtained by observing the structure with a scanning electron microscope. In terms of mass%, two or more of titanium nitride, titanium carbonitride, and titanium carbide as the above-mentioned continuous binder phase forming component, or titanium carbonitride: 15 to 56%, and Ti and Al as the above intermediate adhesion phase forming components A composite nitride of: 2 to 10%, tungsten carbide: 2 to 10%, a cubic boron nitride as the hard dispersed phase forming component: the rest (however, containing 40 to 65%), a press having a compounding composition A cutting tip made of a cubic boron nitride-based ultra-high pressure sintered material having excellent chipping resistance, characterized by being made of a cubic boron nitride-based ultra-high pressure sintered material which is a sintered body of a compact. 2. A cubic with excellent chipping resistance according to claim 1, wherein a titanium nitride layer having an average layer thickness of 0.5 to 5 μm is formed by vapor deposition on the surface of the cutting tip as a discrimination layer before and after use of the tip. Cutting tip made of boron nitride based ultra high pressure sintered material.