JP2021126717A - Surface-coating cutting tool - Google Patents

Abstract

To provide a cutting tool that exhibits excellent welding peeling resistance in high speed cutting of Ti alloy, Ni alloy, etc., and exhibits cutting performance for a long period of time.SOLUTION: In a surface-coating cutting tool, a hard coating layer has: a hard film with an average thickness of 0.5 to 10.0 μm, a W film with an average thickness of 10 to 500 nm right above a tool base body in an interface area between the tool base body and the hard film, and a composition gradient film on right above the W film and in contact with the hard film; the average composition of the hard film is (Ti(1-x-y)AlxMy)N, 0.40≤x≤0.90, and 0.00≤y≤0.20 (M is a group of one of 4 to 6, and one or more of Si, Ce, La, Hf, Nd); the composition gradient film has an average thickness of 10 nm or more and is equal to or less than 1/3 of the hard coating layer, and its average composition is(Ti(1-p-q)AlpMq)N, 0.10≤p<0.40, and 0.00≤q≤0.20 (M is a group of one of 4 to 6, one or more of Si, Ce, La, Hf, Nd); and p increases toward the hard film from a boundary with the W film.SELECTED DRAWING: Figure 1

Description

According to the present invention, even when used for high-speed cutting of titanium alloys, nickel alloys, etc., the hard film layer has excellent welding resistance and chipping resistance, and surface coating cutting that exhibits excellent cutting performance over a long period of use. It relates to a tool (hereinafter sometimes referred to as a covering tool).

Covering tools are used for inserts that are detachably attached to the tip of a cutting tool for turning and planing of various types of steel and cast iron, and for drilling and cutting of work materials. There are drills and miniature drills, as well as solid type end mills used for surface machining, grooving, shoulder machining, etc. of work materials, and inserts can be attached and detached to perform cutting in the same way as solid type end mills. Insert type end mills and the like are known.

Conventionally, as a covering tool, for example, a tool having a hard coating layer formed on a tool substrate such as a WC-based cemented carbide has been known, and attention is paid to the interface between the tool substrate and the hard coating layer to improve the cutting performance. Various proposals have been made for the purpose of improvement.

For example, Patent Document 1 describes a coating tool having a modified layer containing W, Cr, and Co having a bcc structure on the surface of a WC-based cemented carbide substrate, and the coating tool includes high-hardness steel, stainless steel, and cast steel. It is stated that it can be used for cutting.

Further, for example, Patent Documents 2 and 3 describe a coating tool indexed by the crystal structure of WC and provided with an intermediate film having a thickness of 1 to 10 nm composed of carbides containing W and Cr, and this coating is provided. It is stated that the tool is durable even in cutting of high carbon steel, pre-hardened steel and the like.

Japanese Unexamined Patent Publication No. 2014-152345 Japanese Unexamined Patent Publication No. 2016-64487 Japanese Patent No. 638233

The coating tools having a hard coating layer described in Patent Documents 1 to 3 mainly process steel, and have low thermal conductivity, hardness, toughness and cutting like titanium alloys and nickel alloys. At the time of high-speed cutting of a material having a high affinity with a tool, welding peeling occurs at an early stage in the hard film layer, and the life is reached in a short time, so that it is difficult to obtain satisfactory cutting performance.

Therefore, the present invention has been made in view of such a situation, and even if it is used for cutting a material having low thermal conductivity, hard and high toughness such as titanium alloy and nickel alloy, the hard film layer is formed. It is an object of the present invention to provide a cutting tool that exhibits excellent welding resistance and chipping resistance, and in particular, exhibits excellent cutting performance over a long period of time even at high-speed cutting that is twice or more the normal cutting speed. ..

In order to solve the above problems, the present inventor has diligently studied the composition and structure of the interface region between the hard film and the tool substrate. If a composition gradient film is provided directly above the W film, which is in contact with the hard film, contains more Ti than the hard film, and has a composition gradient film in which the Ti content decreases and the Al content increases toward the hard film, the hard film and the tool substrate are provided. Even if the hard coating layer is about to be welded and peeled off, the film in this interface region suppresses chipping and prevents the particles (WC particles) that make up the tool substrate from falling off. I got a lot of knowledge.

The present invention is based on this finding and is as follows.
"(1) A surface-coated cutting tool having a tool base and a hard film layer on the tool base.
The hard film layer includes a hard film having an average thickness of 0.5 to 10.0 μm, a W film having an average thickness of 10 to 500 nm directly above the tool substrate in the interface region between the tool substrate and the hard film, and the like. A composition gradient film in contact with the hard film is provided directly above the W film.
The hard coating, its composition _formula: When expressed in _{(Ti (1-x-y} ) Al x M y) N, 0.40 ≦ x ≦ 0.90,0.00 ≦ y ≦ 0.20 (However, x and y are atomic ratios, M is an atom of groups 4 to 6 of the periodic table of IUPAC, and at least one of Si, Ce, La, Hf, and Nd).
The composition gradient layer has an average thickness of 10nm or more and the average of the hard coating comprising a thickness of 1/3 or less, the composition _{formula: (Ti (1-p-} q) Al p M q ) When represented by N, 0.10 ≦ p <0.40, 0.00 ≦ q ≦ 0.20 (where p and q are atomic ratios, M is an atom of groups 4 to 6 in the periodic table of IUPAC, The composition satisfies at least one of Si, Ce, La, Hf, and Nd), and the p is increased from the boundary with the W film toward the hard film.
Surface coating cutting tool. "

The surface-coated cutting tool of the present invention has a high Ti content in the composition gradient layer, so that the toughness is improved, and even when used for high-speed cutting of titanium alloys, nickel alloys, etc., the hard film layer has excellent welding resistance. By providing chipping resistance, it demonstrates excellent cutting performance over a long period of use.

It is a schematic diagram of the vertical cross section of the hard film layer in the surface coating cutting tool of this invention.

Hereinafter, the covering tool of the present invention will be described in more detail. In the description of the scope of claims in this specification, when the numerical range is expressed using "A to B" (both A and B are numerical values), the range is the upper limit (B) and the lower limit (A). It includes numerical values. Further, the upper limit (B) and the lower limit (A) are the same unit.

FIG. 1 shows a schematic view of a vertical cross section of a hard coating layer in the covering tool of the present invention. As is clear from FIG. 1, a hard film layer is formed on the tool substrate, and this hard film layer has an interface region in the vicinity of the tool substrate. This interface region has a W film on the tool substrate side and a composition gradient film in contact with the hard film immediately above the W film. These will be described in this order below.

Average film thickness of hard film:
The average film thickness of the hard film constituting the hard film layer in the coating tool of the present invention is 0.5 to 10.0 μm. The reason for setting this range is that if it is less than 0.5 μm, excellent wear resistance cannot be exhibited over a long period of use, while if it exceeds 10.0 μm, the crystal grains of the hard film tend to be coarsened. This is because the effect of improving the chipping resistance cannot be obtained.

Hard film composition:
Hard film constituting the hard coating layer in the coated tool of the present invention, its composition _{formula: (Ti (1-x-} y) Al x M y) when expressed in N, 0.40 ≦ x ≦ 0. 90, 0.00≤y≤0.20 (where x and y are atomic ratios, M is an atom of groups 4 to 6 of the periodic table of IUPAC, and at least one of Si, Ce, La, Hf, and Nd). It is preferable to have a satisfactory average composition.
_{Incidentally, (Ti (1-x-} y) Al x M y) and N is 1: may not be combined in the 1.

The reason for determining the range of x, y as described above is as follows.
If the value of x is less than 0.40, not only high hardness cannot be obtained, but also the crystal grains tend to be coarsened. On the other hand, if it exceeds 0.90, the crystal structure of some crystals is a NaCl-type face-centered cubic. The structure changes to a hexagonal structure, and the hardness decreases. A more preferable range is 0.45 ≦ x ≦ 0.70.
Further, when the average content ratio y of M added as needed exceeds 0.20, the toughness is lowered and chipping and chipping are likely to occur.

Here, regarding the average composition and the average layer thickness of the hard film, the scanning electron microscope (SEM), the transmission electron microscope (TEM), and the energy dispersive X-ray spectroscopy (Engry Dispersive) -It can be obtained by cross-sectional observation using a ray spectrum (EDS).

W film in the interface region:
Immediately above the tool substrate in the interface region, there is a W film in contact with the composition gradient film, and the average thickness thereof, that is, the average until W is detected from the tool substrate toward the hard film and Ti is detected instead of WC. The distance is preferably 10 to 500 nm. When the average thickness of the W film is in this range, the hard film layer has excellent welding resistance and chipping resistance. Since the W film in this region is obtained by sputtering W atoms as described later, it is clearly different from the one formed by W which may diffuse from the tool substrate to the hard film. be.

Interface region composition gradient film:
Immediately above the W film in the interface region, there is a composition gradient film in contact with the hard film. Composition The composition of the graded composition layer _formula: When expressed in _{(Ti (1-p-q} ) Al p M q) N, 0.10 ≦ p <0.40,0.00 ≦ q ≦ 0.20 ( provided that , P, q are atomic ratios, M is an atom of groups 4 to 6 of the periodic table of IUPAC, and at least one of Si, Ce, La, Hf, and Nd). It is preferable that p, which is a ratio of M to the total amount, increases from the boundary with the W film toward the hard film. Here, there is no restriction on the mode of increase, but linearity is preferable.
This composition gradient film has an action of firmly adhering the hard film to the tool substrate, and when it has the above-mentioned gradient composition, this action is more reliably exhibited.
It should be _{noted that (Ti (1-p−q)} Al _{pM q} ) and N do not have to be combined at a ratio of 1: 1.

The average thickness of this composition gradient film, that is, the distance from the tool substrate toward the hard film until Ti is detected and the ratio of Al to the total amount of Ti, Al and M becomes 0.40 or more is 10 nm or more. Moreover, it is preferably 1/3 or less of the average thickness of the hard film. When the average thickness is in this range, the above action is more reliably exerted.

Tool base:
As the tool substrate, any substrate containing WC conventionally known as this type of tool substrate can be used as long as it does not hinder the achievement of the object of the present invention.

Production method:
The hard film layer of the coating tool of the present invention can be produced by using an arc ion plating (AIP) device which is a kind of PVD, and the W film is formed by sputtering a W target. The composition gradient film can be formed by simultaneously sputtering two types of targets, a Ti—Al—M alloy having a predetermined composition and Ti, and the discharge amount of Ti can be gradually reduced (for example, linearly reduced). More preferred. Further, as the hard film, two types of targets, Ti—Al—M alloy and Ti having a predetermined composition, are used, and the discharge amount of Ti is controlled so as to have a predetermined composition.

Next, an example will be described.
Here, as a specific example of the coated tool of the present invention, a tool applied to an insert cutting tool using a WC-based cemented carbide as a tool base will be described, but the tool base may contain WC as described above. The same applies when the tool is applied to a drill, an end mill, or the like.

First, as raw material powders, Co powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and WC powder are prepared, and these raw material powders are blended into the blending composition shown in Table 1, and further. Wax is added, wet-mixed in a ball mill for 72 hours, dried under reduced pressure, press-molded at a pressure of 100 MPa, these powder compacts are sintered, processed to a predetermined size, and according to ISO standard SEEN1203AFTN1. Tool bases 1 to 3 made of WC-based cemented carbide having an insert shape were produced.

Next, in order to form a hard film layer on the tool substrates 1 to 3 using an AIP apparatus having a DC (DC) sputtering vapor deposition source, these are ultrasonically cleaned in acetone and dried in the AIP apparatus. It was mounted along the outer peripheral portion at a position on the rotary table at a predetermined distance in the radial direction from the central axis. Further, as a cathode electrode (evaporation source), a W target, a Ti target, and a Ti—Al—M alloy target for obtaining a hard film having a predetermined composition were arranged.

Then, while holding the evacuating the AIP apparatus ¹⁰ -2 Pa or less of vacuum, after heating the inside of the apparatus to 400 to 1000 ° C. by the heater, set to Ar gas atmosphere 0.1~2.0Pa A DC bias voltage of −200 to -1500 V was applied to the tool substrate rotating while rotating on the rotary table, and the surface of the tool substrate was bombarded with argon ions for 10 to 120 minutes.

As the reaction gas, Ar gas having a partial pressure in the range of 0.1 to 1.0 Pa shown in Table 2 was introduced into the AIP apparatus for a predetermined time, and the temperature inside the furnace also shown in Table 2 was maintained. A predetermined DC bias voltage in the range of -30 to -200 V shown in Table 2 is applied to the tool substrate that rotates while rotating on the above, and the sputtering power of the W target is adjusted to 500 to 1000 W to form a W film. A film was formed.

Subsequently, a predetermined DC bias voltage in the range of -30 to -200 V shown in Table 2 is applied so that the Ti content becomes a predetermined amount, and the Ti target and the Ti—Al—M alloy target (M is By adjusting the arc current in the range of 80 to 240 A (see Table 3), the arc current of the Ti target is linearly reduced, while the arc current of the Ti—Al—M alloy target is kept constant. composition gradient _film: it was formed _{(Ti (1-p-q} ) Al p M q) N film. After that, a predetermined current in the range of 80 to 240A shown in Table 2 is passed between the cathode electrode (evaporation source) made of the Ti—Al—M alloy target and the anode electrode to generate an arc discharge, and a hard film is formed. 1 to 9 of the covering tool of the present invention (hereinafter, referred to as “the tool of the present invention”) shown in Table 3 were produced.

On the other hand, for comparison, each film was vapor-deposited on the tool bases 1 to 3 using the same AIP device as described above under the conditions shown in Table 2, and the film tools of the comparative examples shown in Table 4 (hereinafter referred to as the film tools). (Refered to "Comparative Example Tool") 1 to 3 were produced.

The average layer thickness of each film constituting the hard coating layer, and the composition of the hard film and the composition gradient film are the hard film perpendicular to the surface of the tool bases of the tools 1 to 9 of the present invention and the tools 1 to 3 of the comparative examples produced above. Regarding the layer longitudinal section (section perpendicular to the tool substrate), the width in the direction parallel to the surface of the tool substrate is 10 μm, and the scanning electron microscope (scanning electron microscope) is set so as to include the entire thickness region of the hard film layer. It was determined by cross-sectional observation using a scanning electron microscope (SEM), a transmission electron microscope (TEM), and an energy dispersive X-ray spectroscopy (EDS).

Specifically, as for the average layer thickness, the observed cross section was enlarged 5000 times, and the layer thickness at 5 points was obtained to calculate the average layer thickness. The average composition of the hard film, the composition of the composition gradient film, and the change in the Al content were calculated by performing five EDS line analyzes at equal intervals of 100 μm in the layer thickness direction. Further, only the atoms constituting the hard coating layer of (Ti, Al, M, N) start to be detected, and the Al content is 0 from the point closest to the surface of the tool substrate having an Al content of less than 40 atomic% toward the surface side of the tool substrate. The point of .5 nm was set as the position on the tool base side, and the point of 0.5 nm toward the tool base side was set as the position on the tool surface side rather than the point where the Al content ratio did not increase any more. The positions of these points were measured from the surface of the tool substrate. In Tables 3 and 4, the Al contents at the position on the tool base side and the position on the tool surface side are shown as average values of the five analyzes, respectively. The average layer thickness of the interface region is the distance between the position on the tool substrate side and the position on the tool surface side plus 1 nm.
Tables 3 and 4 show these results.

Next, the tools 1 to 9 of the present invention and the tools 1 to 3 of Comparative Examples were subjected to a single-blade face milling test using a cutter of SE445R0506E. High-speed cutting tests were conducted on nickel alloys and titanium alloys under the following cutting conditions.

Cutting test A:
Work Material: Ni-19% Cr-18.5% Fe-5.2% Cd-5% Ta-3% Mo-0.9% Ti-0.5% Al-0.3% by mass% Block material of Ni-based alloy having a composition of Si-0.2% Mn-0.05% Cu-0.04% C, width 60 mm x length 200 mm Cutting speed: 80 m / min.
Notch: 1.8 mm
Feed: 0.11 mm / tooth.
A wet high-speed high-feed cutting process test (normal cutting speed and feed of 25 to 40 m / min., 0.08 mm / tooth) was performed on the Ni-based alloy under the conditions of. The cutting length was cut to 2.0 m, the flank wear width was measured, and the wear state of the cutting edge was observed.
The results of cutting test A are shown in Table 5.

Cutting test B:
Work material: Block material with a width of 60 mm and a length of 200 mm with a mass% of Ti-6% Al-4% V Cutting speed: 90 m / min.
Notch: 1.8 mm
Feed: 0.12 mm / tooth.
Wet high-speed high-feed cutting processing test of Ti-based alloy under the conditions of (normal cutting speed and feed are 30 to 45 m / min., 0.08 mm / tooth) was performed. The cutting length was cut to 2.0 m, the flank wear width was measured, and the wear state of the cutting edge was observed.
The results of cutting test B are shown in Table 6.

According to the results of Tables 5 and 6, the tools 1 to 9 of the present invention did not cause abnormal damage such as chipping and peeling under any of the cutting conditions A and B, and were either weld resistant or chipping resistant. It turns out that is also excellent.
On the other hand, it is clear that the tools 1 to 3 of Comparative Examples reach their end of life in a short time due to the occurrence of chipping or the progress of flank wear under any of the cutting conditions A and B.

The surface-coated cutting tool of the present invention can be used not only for cutting under normal cutting conditions such as various types of steel, but also for titanium alloys, nickel alloys, etc. In high-speed cutting, it exhibits excellent welding resistance and chipping resistance, and exhibits excellent cutting performance over a long period of time. Furthermore, it is possible to sufficiently satisfy the cost reduction.

Claims (1)

A surface-coated cutting tool having a tool substrate and a hard film layer on the tool substrate.
The hard film layer includes a hard film having an average thickness of 0.5 to 10.0 μm, a W film having an average thickness of 10 to 500 nm directly above the tool substrate in the interface region between the tool substrate and the hard film, and the like. A composition gradient film in contact with the hard film is provided directly above the W film.
The hard coating, its composition _formula: When expressed in _{(Ti (1-x-y} ) Al x M y) N, 0.40 ≦ x ≦ 0.90,0.00 ≦ y ≦ 0.20 (However, x and y are atomic ratios, M is an atom of groups 4 to 6 of the periodic table of IUPAC, and at least one of Si, Ce, La, Hf, and Nd).
The composition gradient layer has an average thickness of 10nm or more and the average of the hard coating comprising a thickness of 1/3 or less, the composition _{formula: (Ti (1-p-} q) Al p M q ) When represented by N, 0.10 ≦ p <0.40, 0.00 ≦ q ≦ 0.20 (where p and q are atomic ratios, M is an atom of groups 4 to 6 in the periodic table of IUPAC, The composition satisfies at least one of Si, Ce, La, Hf, and Nd), and the p is increased from the boundary with the W film toward the hard film.
Surface coating cutting tool.

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