JP4069749B2 - Cutting tool for roughing - Google Patents

Description

【００３６】
表１の結果から明らかなように、本発明の試料Ｎｏ．１〜３、５〜７、１０、１１は、いずれも高い強度、硬度を有するとともに荒加工切削においても試料Ｎｏ．１６の超硬合金なみの優れた切削特性を示した。
【００３７】
これに対して、Ｎｉ＋Ｃｏ含有量が１５質量％より少ない試料Ｎｏ．１３では抗折強度が低く、荒加工条件では早期に欠損が発生してしまった。また、Ｎｉ＋Ｃｏ含有量が２２質量％を超える試料Ｎｏ．１５では，金属冨化層が厚くなり耐酸化性および耐塑性変形性が低下し、刃先が摩滅した。
【００３８】
さらに、周期律表４ａ、５ａおよび６ａ族金属総量に対してＴｉの含有量が５５質量％より少ない試料Ｎｏ．１２ではチップの刃先が早期に欠損が発生してしまい、周期律表４ａ、５ａおよび６ａ族金属総量に対してＴｉの含有量が８０質量％を超える試料Ｎｏ．１２では摩耗が進行して早期に切削不能となった。さらに、複合金属炭窒化物の平均粒径が１μｍを超える試料Ｎｏ．４、１４では、荒加工切削で早期に欠損が発生してしまった。
【００３９】
【発明の効果】
以上詳述したように、本発明の切削工具は、ＴｉＣＮ基サーメットでありながら、Ｔｉおよび結合相の含有量、硬質相の粒径を最適化することにより、荒加工領域において超硬合金と同等またはそれ以上の高い切削性能を発揮する工具を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cutting tool comprising a TiCN-based cermet and having high cutting performance for rough machining.
[0002]
[Prior art]
Conventionally, as a material of a throw-away tip for cutting, a cemented carbide obtained by bonding a hard phase made of tungsten carbide with a binder phase of Co (see, for example, Patent Documents 1 and 2), Ti, and a periodic rule other than Ti Table 4a, 5a and TiCN-based cermets in which a hard phase composed of a composite metal carbonitride with at least one of group 6a metals is bonded with a Co and / or Ni bonded phase (for example, Patent Documents 3 and 4) Are mainly used. By the way, currently, cemented carbide is used in a wide range of machining areas from finishing to roughing, but TiCN-based cermets are used in the finishing area by taking advantage of high wear resistance and excellent reaction resistance with steel materials. It is the reality.
[0003]
[Patent Document 1]
JP-A-8-57703 [Patent Document 2]
JP 2001-329331 A [Patent Document 3]
JP 2001-277008 A [Patent Document 4]
JP-A-9-239605 [0004]
[Problems to be solved by the invention]
However, in recent years, there has been a fear of exhaustion of tungsten carbide, and a TiCN-based cermet that exhibits high cutting performance in a wide range of workable areas, particularly in a rough machining region, is desired.
[0005]
However, when conventional TiCN-based cermets such as Patent Documents 3 and 4 are used for roughing, the impact applied to the cutting tool is larger than that for finishing. There was a problem that it did not reach the cutting performance of hard alloys.
[0006]
Accordingly, the present invention has been made to solve the above-mentioned problems, and the object thereof is cutting for rough machining comprising a TiCN-based cermet that exhibits cutting performance equal to or higher than that of cemented carbide in a rough machining region. To provide a tool.
[0007]
[Means for Solving the Problems]
As a result of studying the structure of the cermet suitable for the above rough machining, the present inventor has optimized the content of Ti and binder phase and the particle size of the hard phase to be equivalent to the cemented carbide in the rough machining region. It was also found that a cermet exhibiting a higher cutting performance than that can be obtained.
[0008]
That is, the roughing cutting tool of the present invention includes a binder phase mainly composed of Co and / or Ni, and a hard phase composed of a carbonitride of periodic table 4a, 5a and 6a metal mainly composed of Ti. A TiCN-based cermet consisting of 15 to 22% by mass of Co and Ni, and 55 to 80% by mass of Ti with respect to the total amount of group 4a, 5a and 6a metals, and cermet A binder phase in which the average crystal grain size of the hard phase in the center is 0.6 to 0.9 μm, and the binder phase concentration gradually increases from the surface of the cermet to the extreme surface of 0.01 to 5 μm in thickness. It is characterized by the presence of an enriched region .
[0009]
In addition, the cermet pole surface has a binder phase enriched region in which the binder phase concentration gradually increases, so that the cermet has a fracture resistance that can withstand roughing regions , and has a physical vapor deposition or chemical vapor deposition film, etc. Even when formed, excellent adhesion to the tool body can be maintained. Binding phase enriched area of this it is important to present a thickness of 0.01 to 5 [mu] m.
[0010]
Further, just above the surface of the cermet, (Ti _x M _1-x ) (C _y N _1-y ) (where M is a periodic table other than Ti, 4a, 5a and 6a group metals, Al, Si 1 or more, by becoming covering the hard layer represented by 0.4 ≦ x ≦ 1,0 ≦ y ≦ 1), we were both excellent wear resistance and chipping resistance onset volatilizing be able to.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The cutting tool of the present invention is a TiCN-based cermet comprising a binder phase mainly composed of Co and / or Ni and a hard phase composed of a carbonitride of periodic table 4a, 5a and 6a metal mainly composed of Ti. However, according to the present invention, the present invention relates to a tool particularly suitable for rough machining.
[0012]
Here, the roughing region in the present invention refers to processing in a wet or dry state, particularly turning, with a feed of 0.30 mm / rev (rotation) or more, a cutting depth of 2.0 mm or more, and a cutting speed of 250 m / min or more. Point to.
[0013]
According to the present invention, it is important to contain the Co and Ni in a total amount of 15 to 22% by mass in order to obtain a tool suitable for rough machining. That is, when the binder phase content is less than 15% by mass, desired strength and impact resistance cannot be obtained, and conversely, when the binder phase content exceeds 22% by mass, the wear resistance rapidly decreases. In either case, when used for rough machining, the immediate chipping and the plastic deformation of the cutting edge are poor and wear away, making it impossible to obtain excellent cutting performance. Co and Ni are preferably contained in a proportion of 16 to 20% by mass, more preferably 17 to 19.5% by mass.
[0014]
Further, according to the present invention, it is important to contain 55 to 80% by mass of Ti with respect to the total amount of the periodic table 4a, 5a and 6a group metal in the cermet. This is because if the amount of Ti is less than 55% by mass, the strength required for roughing cannot be ensured. Conversely, if the amount of Ti exceeds 80% by mass, the toughness is reduced and the impact resistance during roughing is reduced. descend. In particular, the Ti content is preferably 65 to 77 mass%.
[0015]
The periodic table 4a, 5a and 6a group metals containing Ti form a composite metal carbonitride as a hard phase. In particular, the hard phase has a core portion made of TiCN, Ti, and a period other than Ti. Table 4a, 5a, and 6a group metals, especially composed of at least one of composite carbide, composite nitride, and composite carbonitride with one or more of W, Mo, Ta and Nb The double-core structure or triple-core structure has the effect of controlling grain growth, and the cermet substrate has a fine and uniform structure, and has excellent wettability with the binder phase and high cermet performance. It is desirable in that it contributes to strengthening.
[0016]
Furthermore, according to the present invention, the average crystal grain size of the hard phase at the center of the cutting tool is 0 . It is important that the thickness is 6 to 0.9 μm, and further 0.7 to 0.9 μm. In other words, if the average crystal grain size of the hard phase is smaller than 0.6 μm, the hard phase tends to agglomerate, resulting in a non-uniform structure, and the impact resistance and hardness of the cermet are reduced. Abrasion is reduced. On the other hand, when the average crystal grain size of the hard phase exceeds 0.9 μm, the strength of the cermet is lowered and the chip resistance of the chip is lowered.
[0017]
In the cutting tool of the present invention, it is important that a binder phase-enriched region where the binder phase concentration gradually increases exists on the extreme surface of the cermet. The presence of such a binder phase-enriched region can increase the thermal conductivity of the cutting blade of the cutting tool, thereby increasing the heat dissipation of the cutting blade and increasing the fracture resistance under severe cutting conditions during rough machining. be able to. This also has the effect that the cutting edge is slightly deformed with respect to the shape of the processed surface of the work material and the surface roughness of the processed surface of the work material is smoothed. The thickness of the binder phase-enriched region is 0.01 to 5 μm from the outermost surface as a region having a binder phase amount of 1.1 times or more with respect to the binder phase amount at the center portion of the cutting tool, 1 to 3 [mu] m, further in conjunction with it is 1~2.5μm enhances the heat conductivity, it is important to suppress excessive plastic deformation at the tool cutting edge.
[0018]
In addition, the average crystal grain size r ₁ of the hard phase on the surface of the cermet substrate is the average crystal grain of the hard phase at the center of the cermet in terms of adhesion to the hard coating layer, which will be described later, improvement in thermal conductivity, and suppression of plastic deformation. It is desirable that it is larger than the diameter r ₂ , specifically, r ₁ = 0.5 to ₂ μm.
[0019]
Furthermore, according to the present invention, (Ti _x M _1-x ) (C _y N _1-y ) (where M is a periodic table other than Ti, group 4a, 5a and 6a metals, Al And a hard coating layer (hereinafter abbreviated as Ti-based coating layer) represented by one or more of Si, 0.4 <x ≦ 1, 0 ≦ y ≦ 1). It is important that the cermet is formed immediately above the cermet base material. Furthermore, from the viewpoint of heat resistance such as high hardness and high temperature stability, M is most preferably one selected from the group consisting of Al, Si, Zr and Cr, and most preferably Al.
[0020]
In addition to the Ti-based coating layer, the hard coating layer includes, for example, one or more of diamond, cubic boron nitride, alumina, Zr, Hf, Cr, Si carbide, nitride, and carbonitride. Other hard coating layers can also be formed.
[0021]
To manufacture a cutting tool comprising the TiCN-based cermet of the present invention, first, as raw material powder, as a hard phase forming component, TiCN powder, and carbides, nitrides, and carbonitrides of periodic table 4a, 5a and 6a metals Using at least one kind of powder selected from the group, Ti is weighed so that the Ti amount is 55 to 80% by mass, particularly 65 to 77% by mass with respect to the total amount of the metals in Group 4a, 5a and 6a. Moreover, it mix | blends so that the ratio of N / (C + N) of carbon (C) and nitrogen (N) in the whole hard phase formation component may be 0.4-0.6.
[0022]
Further, the TiCN powder used at this time needs to be a fine powder having an average particle diameter of 0.4 to 1.0 μm. If the average particle size of the TiCN powder at this time is larger than 1.0 μm, it becomes difficult to make the average crystal particle size of the hard phase in the cermet 1 μm or less. Moreover, when smaller than 0.4 micrometer, it will become difficult to make the said average crystal grain diameter of a hard phase 0.5 micrometer or more.
[0023]
The average particle size of at least one powder selected from the group of carbides, nitrides, and carbonitrides of Group 4a, 5a, and 6a metals is suitably 0.5-2 μm.
[0024]
Further, Ni and / or Co powder having an average particle size of 0.3 to 4 μm is added as a binder phase forming component at a ratio of 15 to 22% by mass.
[0025]
These weighed powders are mixed by a ball mill or the like, then formed into a predetermined cutting tool shape by a known forming method such as press molding, extrusion molding or injection molding, and then fired.
[0026]
In firing, in order to form a hard phase with a cored structure and suppress grain growth of the hard phase, the temperature is raised from room temperature to around 950 ° C. at 10 to 15 ° C./min at a vacuum degree of 0.01 Torr or less. After that, the temperature is raised to about 1300 ° C. at 1 to 5 ° C./min, further raised to 1500 ° C. to 1600 ° C. at 3 ° C. to 15 ° C./min, and allowed to cool to room temperature within a holding time of 1 hour. It is desirable to bake under conditions of cooling at 10 ° C. to 15 ° C./min.
[0027]
Further, in order to form a binder phase enriched region on the cermet surface, nitrogen gas is treated in a nitrogen gas of 0.1 to 0.3 kPa from room temperature to 1250 ° C. to 1350 ° C. under the above firing conditions, Only during the temperature rising process from 1250 ° C to 1350 ° C to 1500 to 1600 ° C, the vacuum is set to 0.01 Torr or less, and after firing at 1500 ° C to 1600 ° C, the vacuum is set to 0.01 Torr or less to 10 ° C to 15 ° C / min. It is desirable to cool with.
[0028]
In addition, using the TiCN-based cermet produced by the above method as a base material, a chemical vapor deposition method (CVD method), a physical vapor deposition method such as a sputtering method, an ion plating method, a vapor deposition method (on the surface) A coating layer as described above may be formed by a PVD method or the like.
[0029]
【Example】
As the raw material powder, TiCN powder having an average particle diameter shown in Table 1, and TiN powder having an average particle diameter of 0.5 to 2 μm, TaC powder, NbC powder, WC powder, ZrC powder, VC powder, and average particle diameter Co powder of 2 μm, Ni powder or alloy powder of Co and Ni were used, these raw material powders were blended in the blending composition shown in Table 1, and wet mixed and pulverized by a ball mill. The average particle diameter is measured by the microtrack method.
[0030]
Next, the mixed powder is press-molded into a chip shape and a bent specimen shape at a molding pressure of 98 MPa, and each molded body is heated to 950 ° C. at a rate of 12 ° C./min in a vacuum of 0.01 Torr or less. The temperature was raised from 950 ° C. to 1300 ° C. at 2 ° C./minute, raised to the firing temperature shown in Table 1 at 5 ° C./minute, held for 1 hour, and then cooled to room temperature at 12 ° C./minute in vacuum. Thus, a cermet having a shape of CNMG120408 was produced. Sample No. 8 and 9 were fired in the same manner as described above, except that the temperature was raised to 1300 ° C. in 0.2 KPa nitrogen.
[0031]
About the produced cermet, while measuring three-point bending strength according to JISR1601, the toughness (IF method) was measured according to JISR1607. The results are shown in Table 2.
[0032]
Furthermore, the cross-section of the obtained chip center was observed with an electron microscope, and the crystal grain size of the hard phase was measured by the intercept method at two observation regions of 7 × 7 μm, and the average crystal grain size was measured.
[0033]
Further, the concentration change of Ni and Co in the binder phase near the surface of the chip is measured by EPMA method, the change in concentration of Ni + Co is observed by adding the concentration change of Ni and Co, and the concentration of the central portion from the surface is observed. The thickness up to a region having a concentration of 1.1 times or more of the thickness was measured at three locations, and the average was determined.
[0034]
Further, for each of the 10 throwaway chips obtained, cutting was performed under the following rough cutting condition A, and Table 1 shows the feed when missing.
Cutting condition Work material: SCM435
Work material: Round groove with 4 grooves Cutting speed: 250 m / min
Feeding and cutting time: After cutting at 0.1 mm / rev for 10 seconds, feed is increased by 0.05 mm / rev and cut for 10 seconds each (up to a maximum feed of 0.5 mm / rev)
Cutting depth: 2mm
[0035]
[Table 1]

[0036]
As is clear from the results in Table 1, sample No. 1-3, 5-7, 10 and 11 all have high strength and hardness, and also in sample cutting with rough machining. Excellent cutting characteristics of 16 cemented carbides.
[0037]
In contrast, Sample No. with a Ni + Co content of less than 15% by mass. In No. 13, the bending strength was low, and the chipping occurred early in the roughing condition. Further, Sample No. with Ni + Co content exceeding 22 mass%. In No. 15, the metal hatched layer was thickened, the oxidation resistance and plastic deformation resistance were lowered, and the cutting edge was worn.
[0038]
Furthermore, the sample No. 5 containing less than 55% by mass of Ti with respect to the total amount of the periodic table 4a, 5a and 6a group metals. In No. 12, the cutting edge of the tip was damaged early, and the sample No. No. 1 in which the Ti content exceeded 80% by mass with respect to the total amount of metals in the periodic tables 4a, 5a, and 6a. In No. 12, wear progressed and cutting became impossible early. Further, Sample No. with an average particle size of the composite metal carbonitride exceeding 1 μm. In Nos. 4 and 14, the chipping occurred early in the roughing cutting.
[0039]
【The invention's effect】
As described above in detail, the cutting tool of the present invention is equivalent to a cemented carbide in the rough machining region by optimizing the content of Ti and binder phase and the particle size of the hard phase while being a TiCN-based cermet. Alternatively, a tool that exhibits a higher cutting performance than that can be provided.

Claims (2)

A TiCN-based cermet composed of a binder phase mainly composed of Co and / or Ni and a hard phase composed of a carbonitride of the periodic table 4a, 5a and 6a metals mainly composed of Ti, and the Co and Ni 15 to 22% by mass in a total amount, 55 to 80% by mass of Ti with respect to the total amount of metals in the periodic tables 4a, 5a and 6a, and the average crystal grain size of the hard phase in the center of the cermet The roughness is 0.6 to 0.9 μm, and there is a bonded phase enriched region in which the binder phase concentration gradually increases from the surface of the cermet to the extreme surface having a thickness of 0.01 to 5 μm. Cutting tool for machining. Just above the surface of the cermet, (Ti _x M _1-x ) (C _y N _1-y ) (where M is one of the periodic table 4a, 5a and 6a group metals other than Ti, Al, Si) above, 0.4 ≦ x ≦ 1,0 ≦ y ≦ 1) roughing cutting tool according to claim 1 Symbol mounting, characterized in that formed by coating a hard coating layer represented by.