JP2003236710A - Cutting tip made of cubic crystal boron nitride group ultrahigh pressure sintered material having excellent resistance to chipping - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tip made of a cubic crystal boron nitride group ultrahigh pressure sintered material having excellent resistance to chipping. <P>SOLUTION: This cutting tip made of the cubic crystal boron nitride group ultrahigh pressure sintered material is made of the cubic crystal boron nitride group ultrahigh pressure sintered material which is a sintered body of press molding having a blending composition composed of two kinds or more of titanium nitride, titanium carbonitride, and titanium carbide or titanium carbonitride as a continuous connection phase formation component of 10 to 36% by mass % which show three phase texture of a continuous connection phase, a hard dispersed phase, and an intermediate close adhesion phase provided between the continuous connection phase and the hard dispersed phase substantially by observation of texture using a scanning type electronic microscope, any of tantalum carbide and niobium carbide or both of them of 5 to 20%, composite nitride of Ti and Al as an intermediate close adhesion phase formation component of 2 to 10%, tungusten carbide of 2 to 10%, and cubic crystal boron nitride as a hard dispersed phase formation component of remaining parts (containing 40 to 65%). <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): 10 to 36%, tantalum carbide (hereinafter, TaC) and niobium carbide (hereinafter, NbC) Either or both: 5 to 20
%, As the hard dispersed phase forming component, cubic boron nitride (hereinafter referred to as c-BN): the rest, a cubic boron nitride-based ultrahigh pressure which is a sintered body of a press-molded product A c-BN-based sintered cutting tip made of a sintered material (hereinafter referred to as a c-BN-based material) is known, and is used for surface finishing cutting of various steels and cast irons, for example. Is also known.

[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 TiN powder and TiCN powder, TaC powder and NbC powder, a composite nitride of Ti and Al [hereinafter (Ti, Al) N] powder and tungsten carbide (hereinafter WC) powder are also added. Used as raw material powder,
These are represented by mass% (hereinafter,% represents mass%) in Ti
Two or more of N, TiCN, and TiC, or TiCN: 10 to 36%, either TaC or NbC, or both: 5 to 20%, (Ti, Al) N: 2 to
10%, WC: 2 to 10%, c-BN: rest (however,
40-65% content), and when the press-formed body formed by mixing and mixing is subjected to ultra-high pressure sintering, (Ti, Al) N powder and WC powder among these components are
During sintering, the c-BN powder is preferentially aggregated on the surface of the c-BN powder and reacts to form a reaction product, and in the c-BN-based material after sintering, the reaction product is substantially a continuous binder phase forming component. Which is a mixture of two or more of TiN, TiCN, and TiC, or a solid solution of TiCN and either or both of TaC and NbC, and Ti and Ta, and / or
Alternatively, a compound carbonitride of Nb [hereinafter, (Ti, Ta / N
b) Shown as CN] continuous bonded phase composed of phases and c-BN
Interspersed between the hard dispersed phase composed of phases,
Moreover, this reaction product is a product of (Ti, T
a / Nb) It adheres extremely strongly to both the CN phase and the above-mentioned c-BN phase of the hard dispersed phase, and acts as an intermediate adhesion phase. Therefore, c composed of this c-BN-based material
-BN-based sintered cutting chips can be used for high-speed finishing cutting of hard-to-cut materials such as high-hardness hardened steel even when they are used for high-speed finish cutting. We obtained the results of research that shows excellent cutting performance over a long period of time without any occurrence.

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. 3 shows a three-phase structure of an intermediate coherent phase interposed between the two.
Two or more of iCN and TiC, or TiC
N: 10 to 36%, either or both of TaC and NbC: 5 to 20%, (Ti, Al) N: 2 to 10%, WC: 2 to 10 as the above-mentioned intermediate adhesion phase forming component.
%, As the hard dispersed phase forming component, a c-BN base material which is a sintered body of a press-molded product having a compounding composition of c-BN: the rest (however, containing 40 to 65%). It is characterized by a c-BN-based sintered cutting tip having excellent chipping resistance.

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 improve the sinterability as well as TaC.
And NbC form a continuous bonded phase to improve the strength and toughness of the c-BN based material, but if the blending ratio is less than 10%, the desired improving effect on the above operation cannot be obtained. If the blending ratio exceeds 36%, the wear resistance will suddenly decrease, so the blending ratio was set to 10 to 36%.

(B) TaC and NbC These components include TiN and TiC during sintering as described above.
N and TiC are solid-solved with each other (Ti, Ta /
Nb) has a function of forming a continuous bonded phase composed of CN phase and improving the high temperature strength thereof, but its compounding ratio is 5%
If it is less than the above range, the desired effect of improving high-temperature strength cannot be obtained, while if the blending ratio exceeds 20%, the wear resistance will be rapidly reduced, so that the blending ratio is set to 5 to 20%.

(C) (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,
It is a c-BN based material after sintering, and the (Ti,
It comes to intervene between the Ta / Nb) CN phase and the c-BN phase of the hard dispersed phase. Moreover, since this reaction product has the property of firmly adhering to both the (Ti, Ta / Nb) CN phase of the continuous binding phase and the c-BN phase of the hard dispersed phase, the above-mentioned c-BN The adhesion of the phase to the (Ti, Ta / Nb) CN phase, which is a continuous bonded phase, is remarkably improved, and as a result, the chipping resistance of the cutting edge is improved. Even if the ratio is out of the above range, it is not possible to secure a strong adhesiveness between the hard dispersed phase and the continuous binder phase as an intermediate adhesive phase, and therefore, the above-mentioned content of (Ti, Al) N and WC cannot be ensured. The blending ratio is empirically determined in order to secure strong adhesion.

(D) c-BN c-BN which constitutes the hard dispersed phase is extremely hard, and this improves wear resistance. However, if the compounding ratio is less than 40%, 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 40-
It was set at 65%. The c-BN-based sintered cutting tip of the present invention described above has titanium nitride (hereinafter, referred to as T) having a golden color tone on its surface as a discrimination layer before and after using the cutting tip.
(denoted by iN) may be formed by vapor deposition. In this case, if the average layer thickness is less than 0.5 μm, a golden color tone sufficient for discrimination cannot be imparted, while the discrimination is 5 μm.
Since the average layer thickness up to 0.5 is sufficient, 0.5-5 μm
The average layer thickness of

[0010]

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, TiCN powder, TiC powder, TaC powder, and N for forming a continuous binder phase, each having a predetermined average particle diameter within the range of 0.5 to 2 μm,
bC powder, WC powder for forming an intermediate contact phase, and (Ti, Al) N powder (Ti _0.65 Al _0.35 ) N
[Hereinafter, represented by (Ti, Al) N-1] powder, (Ti
_0.50 Al _0.50 ) N [hereinafter referred to as (Ti, Al) N-2] powder, and (Ti _0.35 Al _0.65 ) N [hereinafter referred to as (T
i, Al) N-3] powder (both numbers in composition formula indicate atomic ratio), and c-BN powder for forming hard dispersed phase are prepared. Compounded with the compounding composition shown in Fig. 1, wet mixed with a ball mill for 72 hours, dried, and then at a pressure of 100 MPa, diameter: 50 m.
m × thickness: press-formed into a compact having a dimension of 1.5 mm, and the compact is pressed in a vacuum atmosphere at a pressure of 1 Pa for 90
Pre-sintering under the condition of holding at a predetermined temperature within the range of 0 to 1300 ° C. for 1 hour, and then separately preparing this diameter: 50
mm × thickness: The cemented carbide chips (composition: WC-8% Co) having a size of 2 mm are placed in a super-high pressure sintering apparatus in a state of being superposed, and a predetermined temperature within a range of 1200 to 1400 ° C. Sintered under a pressure of 5 GPa for 30 minutes, the upper and lower surfaces were ground with a diamond grindstone after sintering, and the size was adjusted by wire cutting by arc discharge. Invention c-BN based sintered cutting chips (hereinafter referred to as the present invention cutting chips) 1 to 12 and comparative c-BN based sintered cutting chips (hereinafter referred to as the comparative cutting chips) 1 to 12 were manufactured. The comparative cutting chips 1 to 12 are all intermediate adhesion phase forming components (T
The compounding ratio of at least one of the i, Al) N powder and the WC powder 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, the inside of the device is evacuated to 0.5 Pa.
While maintaining the vacuum below, use a heater to
After heating to ℃, a DC bias voltage of −1000V is applied to the cutting tip, while the metal T of the cathode electrode is applied.
A current of 100 A is passed between i and the anode electrode to generate an arc discharge, so that the surface of the cutting tip is Ti.
After bombard cleaning, nitrogen gas was introduced into the device 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 100
A current of A is applied to generate an 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. As a result, 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.

[0012] Further, these cutting tips are brazed to a cutting step formed at the tip of the cutting edge of a cemented carbide body (composition: WC-10% Co) to JIS / TN.
It is a throwaway type cutting tool with the shape specified in MA160408. Work material: Carburized and hardened steel (JIS SCM415, hardness: HRC62) Eight-grooved round bar at equal intervals in the length direction, Cutting speed: 250 m / Min, depth of cut: 0.15 mm, feed: 0.2 mm / rev, cutting time: 30 minutes, dry high-speed surface finish cutting test of difficult-to-cut materials was performed, and flank wear width of cutting edge was measured. .. The measurement results are shown in Tables 1 and 2. Further, on the surface of the cutting tip, Ti having a golden color tone as a discrimination layer before and after using the cutting tip
When the surface after the above-mentioned cutting test was observed for the one in which the N layer was vapor-deposited and formed, it was found that the chip contact portion of the rake face and the flank of the cutting edge part and the ridge line part of the cutting edge where the rake face and the flank intersect The TiN layer is worn away, and the gray tone of the cutting chip base material is exposed in the worn portion of the TiN layer.
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.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

From the results shown in Tables 1 and 2, the cutting tips 1 to 12 of the present invention can be chipped to the cutting edge even when the surface finish cutting of the carburized and hardened steel, which is a difficult-to-cut material, is performed at high speed. It does not occur, exhibits excellent wear resistance, and exhibits excellent cutting performance for a long period of time, while it is an intermediate adhesion phase forming component (Ti, Al as shown in Comparative Cutting Tips 1-12). ) Even if the blending ratio of at least one of N powder and WC powder deviates from the range of the present invention, it is clear that chipping occurs in the cutting edge, which causes the service life to be reached in a relatively short time. As mentioned above,
In the c-BN-based sintered cutting tip of the present invention, the c-BN phase that constitutes the hard dispersed phase is substantially a (Ti, Ta / Nb) CN phase that constitutes a substantially continuous bonded phase due to the interposition of the intermediate adhesion phase. It adheres firmly, and it exhibits excellent chipping resistance not only for cutting under normal conditions, but also for high-speed surface finishing cutting of difficult-to-cut materials such as hardened hardened steel as described above. It can fully satisfy the needs for high performance and high output of equipment, labor saving and energy saving for cutting.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Seki Nakata             1002-14 Mukoyama, Naka-machi, Naka-gun, Ibaraki Prefecture             Terari Co., Ltd.             Inside (72) Inventor Kazuo Yamamoto             1002-14 Mukoyama, Naka-machi, Naka-gun, Ibaraki Prefecture             Terari Co., Ltd.             Inside F-term (reference) 3C046 FF35 FF40 FF42 FF44 FF48                       FF52 HH06                 4G001 BA24 BA25 BA34 BA36 BA38                       BA57 BB24 BB25 BB34 BB36                       BB38 BB57 BC23 BC42 BC46                       BC55 BC61 BC72 BC73 BD12                       BD18 BE11                 4K029 AA04 BA60 BC00 BD05 CA04                       EA01

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 mass%, two or more of titanium nitride, titanium carbonitride, and titanium carbide, or titanium carbonitride: 10 to 36%, one or both of tantalum carbide and niobium carbide, as the continuous binder phase forming component. : 5 to 20%, as the intermediate adhesion phase forming component, Ti / Al composite nitride: 2 to 10%, tungsten carbide: 2 to 10%, as the hard dispersed phase forming component, cubic boron nitride: the rest (Provided that the content is 40 to 65%), which is composed of a cubic boron nitride-based ultra-high pressure sintered material, which is a sintered body of a press-formed body having a compounding composition of Cutting tip made of cubic boron nitride based ultra high pressure sintered material. 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.