JP6959577B2 - Surface coating cutting tool - Google Patents

Description

According to the present invention, in cutting difficult-to-cut materials such as Ti-based alloys and stainless steel, the hard coating layer has excellent lubricity, suppresses the occurrence of welding, chipping, etc., and provides excellent cutting performance over a long period of use. It relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exerts its effect.

Generally, as a covering tool, for turning and planing of various types of steel, cast iron, etc., for throw-away chips that are detachably attached to the tip of a cutting tool, for drilling and cutting of the work material, etc. Known drills and miniature drills, end mills used for surface cutting, grooving, shoulder processing, etc. of the work material, solid hobs, pinion cutters, etc. used for lathe cutting of the tooth profile of the work material, etc. There is.
And, many proposals have been made conventionally for the purpose of improving the cutting performance of the covering tool.

For example, as shown in Patent Document 1, chipping resistance when a high-hardness steel such as a hardened material of an alloy tool steel is subjected to high-speed intermittent cutting conditions in which a high heat is generated and an intermittent / impact load acts. _{, The composition formula: (Cr 1-XY-Z} Al _X Ti _Y B _Z ) N is represented on the surface of the tool substrate for the purpose of improving fracture resistance, peel resistance, and abrasion resistance (however, , X, Y, and Z are all atomic ratios and satisfy 0.40 ≦ X ≦ 0.65, 0.01 ≦ Y ≦ 0.20, 0.005 ≦ Z ≦ 0.08) Cr and A surface coating formed by depositing a hard coating layer made of a composite nitride of Al, Ti, and B, and forming the hard coating layer as an alternating laminated structure of a thin layer A having a granular crystal structure and a thin layer B having a columnar crystal structure. Cutting tools have been proposed.

Further, in Patent Document 2, the composition formula: (Ti _a , Cr _b , Hard film represented by Al _c , S _d , _Be , M _1-ab-c-d-e ) (C _1-f N _f ) (where M is W and / or Mo, 0 <a ≦ 0.7, 0 <b ≦ 0.7, 0.25 ≦ c ≦ 0.75, 0 ≦ d + e ≦ 0.2, 0.03 ≦ (1-ab-c-d-e) ) ≤ 0.35, 0.5 ≤ f ≤ 1) have been proposed.

Japanese Unexamined Patent Publication No. 2011-224671 Japanese Unexamined Patent Publication No. 2011-94241

In recent years, the shift to FA for cutting equipment has been remarkable, while there are strong demands for labor saving, energy saving, and cost reduction for cutting processing, and along with this, cutting processing tends to become faster and more efficient. At the same time, there is a tendency that a versatile cutting tool capable of cutting as many work materials as possible is required.
In the conventional covering tools proposed in Patent Documents 1 and 2, when this is used for cutting under normal cutting conditions such as carbon steel and alloy steel, no particular problem occurs.
However, when used for cutting difficult-to-cut materials such as Ti-based alloys and stainless steel, the lubricity is inferior in the low temperature region at the initial stage of cutting, and the work material and chips become hot due to heat generated during cutting. As a result, the welding property of the coating tool to the surface of the hard coating layer is further increased, and as a result, the occurrence of welding and chipping at the cutting edge is rapidly increased. The current situation is that the service life is reached in a relatively short time due to the cause.

Therefore, the present invention has excellent lubricity in cutting work accompanied by high heat generation of difficult-to-cut materials such as Ti-based alloys and stainless steel, suppresses the occurrence of welding and chipping, and is excellent over a long period of use. It is an object of the present invention to provide a covering tool that exhibits cutting performance.

From the above viewpoint, the present inventors have provided the hard coating layer with excellent lubricity under high-efficiency cutting conditions for difficult-to-cut materials such as Ti-based alloys and stainless steel, thereby providing excellent welding resistance. As a result of intensive research focusing on the component system constituting the hard coating layer in order to develop a coating tool that exhibits chipping resistance, the following findings were obtained.
On the surface of a tool substrate made of tungsten carbide-based cemented carbide, titanium nitride-based cermet, cubic boron nitride sintered body, high-speed tool steel, etc., a composite nitride of Al, Ti, Cr, and B (hereinafter, "( The coating tool provided with a hard coating layer composed of layers (indicated by Al, Ti, Cr, B) N) is well known as a coating tool having excellent wear resistance because it has high-temperature hardness and oxidation resistance. (See Patent Documents 1 and 2 above).
Then, the present inventors improve the lubricity of the hard coating layer at the time of cutting in the coating tool coated with the hard coating layer composed of the (Al, Ti, Cr, B) N layer, and the work material and the hard. By making the coating layer contact via a lubricating film, it can be applied to difficult-to-cut materials such as Ti-based alloys and stainless steel, which are work materials with low thermal conductivity and high chemical affinity with tool materials. The applicability as a cutting tool can be enhanced, and as a result, in high-efficiency cutting of difficult-to-cut materials such as Ti-based alloys and stainless steel, welding, chipping, etc. can be prevented and long-term use is possible. Over the years, it has been found that a covering tool exhibiting excellent wear resistance can be obtained.

That is, in order to improve the lubricity of the hard coating layer composed of the (Al, Ti, Cr, B) N layers, a specific amount of Ag is contained as a component of the hard coating layer, and silver oxide having a melting point of about 100 ° C. is added. By generating it, the lubricity in the low temperature region at the initial stage of cutting is enhanced, and by further containing a specific amount of W as a component of the hard coating layer, it has lubricity at 550 ° C. or higher during cutting. Magneli phase W _{n O 3n-1} is produced, further Magneli phase to become a melting point at 680 ℃ (G.Gassner et al "Surface & Coatings Technology" 201 (2006) 3335 -. see 3341), these cutting Lubrication is imparted to the surface of the hard coating layer by liquefying due to the heat generated at the time.
As described above, the formation of silver oxide or a magnetic phase on the surface of the hard coating layer during cutting makes it possible to impart lubricity to the surface of the hard coating layer in a wide temperature range from low temperature to high temperature.

That is, the coating tool of the present invention contains Ag as a component of the hard coating layer in the hard coating layer composed of the (Al, Ti, Cr, B) N layers, or further contains W. Welding resistance by imparting excellent lubricity in high-efficiency cutting of difficult-to-cut materials such as Ti-based alloys and stainless steel, which are work materials with low thermal conductivity and high chemical affinity with tool materials. It improves the properties and chipping resistance, and as a result, can exhibit excellent cutting performance over a long period of use.

The present invention has been made based on the above findings.
"(1) Surface coating cutting in which a hard coating layer is provided on the surface of a tool substrate made of any one of tungsten carbide-based cemented carbide, titanium nitride-based cermet, cubic boron nitride sintered body, and high-speed tool steel. In the tool
The hard coating layer is a composite nitride layer of Al, Ti, Cr, B, W, and Ag having an average layer thickness of 0.5 to 10 μm .
The composite nitride,
Composition formula: (Al _a Ti _b Cr _{(1- (a + b + c + d + e))} B _c W _d Ag _e ) N
When represented by, 0.40 ≦ a ≦ 0.85, 0.05 ≦ b ≦ 0.30, 0.005 <c ≦ 0.100, 0 <d ≦ 0.100, 0.005 ≦ e ≦ 0 A surface coating cutting tool comprising .050, (where a, b, c, d, e all indicate atomic ratios).
(2) The composition formula: (Al _a Ti _b Cr _{(1- (a + b + c + d + e))} B _c W _d Ag _e ) The Al content ratio a in N satisfies 0.55 ≦ a ≦ 0.68. The surface-coated cutting tool according to (1) above. "
It has the characteristics of.

The present invention will be described in detail below.

Average thickness of composite nitride layer of Al, Ti, Cr, B, W and Ag:
Hard layer of the present invention, a composite nitride of A l Ti, Cr, B, W and Ag (hereinafter sometimes designated "(Al, Ti, Cr, B, W, Ag) N") layer although, (Al, Ti, Cr, B, W, Ag) when the average layer thickness of the N layer is less than 0.5μm can not exhibit sufficient abrasion resistance over long-term use, On the other hand, if the average layer thickness exceeds 10 μm, abnormal damage such as chipping and chipping may occur. Therefore, the average layer thickness of the (Al, Ti, Cr, B, W, Ag) N layer is 0.5. It is desirable to set it to 10 μm.

(Al, Ti, Cr, B, W, Ag) Component composition of N layer:
(Al, Ti, Cr, B, W, Ag) The composition of the components constituting the N layer,
Composition formula: (Al _a Ti _b Cr _{(1- (a + b + c + d + e))} B _c W _d Ag _e ) N
When represented by, 0.40 ≦ a ≦ 0.85, 0.05 ≦ b ≦ 0.30, 0.005 <c ≦ 0.100, 0 <d ≦ 0.100, 0.005 ≦ e ≦ 0 It is necessary to satisfy .050 (where a, b, c, d, and e all indicate atomic ratios) for the following reasons.

(Al, Ti, Cr, B, W, Ag) The Al component, which is a constituent of the N layer, has the effect of improving the high-temperature hardness of the hard coating layer, and the Ti component improves the high-temperature strength. It works. The Cr component also has an effect of improving high-temperature strength, but in particular, heat resistance and high-temperature oxidation resistance are improved by coexisting and containing the Cr component and the Al component.
However, when the Al component content ratio a is less than 0.4, or when the Ti component content ratio b exceeds 0.3, the Al content ratio becomes too small, and the desired excellent high-temperature hardness is obtained. On the other hand, when the content ratio a of the Al component exceeds 0.85 or the content ratio b of the Ti component is less than 0.05, the Ti component is small. If it becomes too high, the high temperature strength will decrease, chipping (micro chips) will easily occur on the cutting edge, and a hexagonal structure phase will be generated and the high temperature hardness will also decrease. It is determined that 0.40 ≦ a ≦ 0.85 and the content ratio b of the Ti component is 0.05 ≦ b ≦ 0.30, respectively.
The content ratio a of the Al component satisfies 0.55 ≦ a ≦ 0.68 in order to exhibit excellent wear resistance over a long period of use while maintaining welding resistance and chipping resistance. Is preferable.

(Al, Ti, Cr, B, W, Ag) The B component, Ag component and W component in the N layer all form oxides due to high heat generation during cutting, and these oxides are liquefied. This contributes to improving the lubricity of the hard coating layer.
The oxides are liquefied at different temperatures (boron oxide is liquefied at about 450 ° C., silver oxide is liquefied at about 100 ° C., and tungsten oxide is liquefied at about 680 ° C.), and W is oxidized at 550 ° C. or higher. Since the material produces a magnetic phase having lubricity, it is possible to impart lubricity to the surface of the hard coating layer in a wide temperature range from low temperature to high temperature during cutting.
However, if the content ratio c of the B component is 0.005 or less or the content ratio e of the Ag component is less than 0.005, sufficient oxides are not formed, so that the effect of improving lubricity is not sufficient.
On the other hand, when the content ratio c of the B component exceeds 0.100, embrittlement is likely to occur, so that chipping is likely to occur, and when the content ratio e of the Ag component exceeds 0.050, the hardness is increased. Decreases.
Therefore, the content ratio c of the B component and the content ratio e of the Ag component are 0.005 <c ≦ 0.100 and 0.005 ≦ e ≦ 0.050, respectively.

Further, when the W component as a constituent component is further contained in the (Al, Ti, Cr, B, W, Ag) N layer, the tungsten oxide forms a magnetic magnelli phase having lubricity, and further. , The liquefaction has the effect of improving the lubricity of the above-mentioned hard coating layer.
However, when the content ratio d of the W component exceeds 0.1, the hardness of the hard coating layer decreases and the wear resistance decreases. Therefore, the content ratio e of the W component is 0 <d ≦ 0.100. (Preferably 0.005 ≦ d ≦ 0.100).

In the (Al, Ti, Cr, B, W, Ag) N layer, the content ratio (atomic ratio) of the N component to the total amount of the components constituting the layer is 0.50, which is a stoichiometric ratio. It is not limited, and may be a range in which an effect equivalent to this can be obtained, for example, a range of 0.40 or more and 0.60 or less.

The (Al, Ti, Cr, B, W, Ag) N layer of the present invention described above is, for example, an arc ion plating (hereinafter referred to as “AIP”) apparatus shown in FIG. 1, which is a kind of physical vapor deposition method. Can be formed using.
(A) First, in the AIP apparatus, a tool substrate composed of either a tungsten carbide-based cemented carbide, a titanium nitride-based cermet, a cubic boron nitride sintered body, or a high-speed tool steel is cleaned and dried. It is mounted along the outer peripheral portion at a position separated by a predetermined distance in the radial direction from the central axis on the rotary table of.
(B) while maintaining the inside of the apparatus to the following vacuum ¹⁰ -2 Pa exhaust, after heating the inside of the apparatus to 500 ° C. by the heater, set to Ar gas atmosphere 0.5～2.0Pa, the rotation A DC bias voltage of −200 to −1000 V is applied to the tool substrate that rotates while rotating on the table, and the surface of the tool substrate is bombarded with argon ions for 5 to 30 minutes.
(C) Subsequently, while maintaining the inside of the apparatus to a vacuum of ¹⁰ -2 Pa, also in the apparatus with a heater, maintained at a temperature of 620 ° C. to 650 ° C.. Next, an arc discharge is generated between the cathode electrode (evaporation source) made of an Al-Ti-Cr-B-W-Ag alloy having a predetermined composition and the anode electrode arranged in the apparatus under the condition of, for example, a current of 100 A. At the same time, nitrogen gas is introduced into the apparatus as a reaction gas to create a reaction atmosphere of, for example, 4 Pa, while the tool is vapor-deposited on the tool substrate under the condition that a bias voltage of, for example, -100 V is applied. An N layer (Al, Ti, Cr, B, W, Ag) having a target composition and a target average layer thickness is formed on the surface of the substrate.
The covering tool of the present invention can be produced by the above steps (a) to (c).

The coated tool of the present invention is used for high-efficiency cutting of difficult-to-cut materials such as Ti-based alloys and stainless steel, which are work materials having low thermal conductivity and high chemical affinity with tool materials. Since the (Al, Ti, Cr, B, W, Ag) N layer of the hard coating layer has excellent lubricity in a wide temperature range from low temperature to high temperature, it is possible to suppress the occurrence of welding, chipping, etc. At the same time, it demonstrates excellent cutting performance over a long period of use.

A schematic explanatory view of an arc ion plating apparatus for forming a hard coating layer of the coating tool of the present invention is shown, (a) is a plan view, and (b) is a side view.

Next, the covering tool of the present invention will be specifically described with reference to Examples.
In the following examples, the case where the covering tool of the present invention is used in milling will be described, but the use in turning, drilling, etc. is not excluded at all.
The case where a WC-based cemented carbide is used as the tool substrate will be described, but the same applies even when a TiCN-based cermet, a cubic boron nitride sintered body, or a high-speed tool steel is used as the tool substrate. The effect is obtained.

_{As raw material powders, WC powder, Cr 3} C ₂ powder and Co powder, each having an average particle size of 1 to 3 μm, are prepared, these raw material powders are blended into the blending composition shown in Table 1, and wax is further added. After mixing with a ball mill in acetone for 24 hours, drying under reduced pressure, press molding into a powder having a predetermined shape at a pressure of 98 MPa, and this powder in a vacuum of 5 Pa, a predetermined value within the range of 1370 to 1470 ° C. Vacuum-sintered under the condition of holding the temperature for 1 hour, and after sintering, a WC-based cemented carbide tool substrate having an insert shape of ISO standard SEEN1203AFEN was manufactured.

(A) These tool substrates are mounted along the outer peripheral portion at a position radially separated from the central axis of the rotary table of the AIP device by a predetermined distance, and Al-Ti-Cr-B having a predetermined composition is installed in the AIP device. A target (cathode electrode) made of −W—Ag alloy is placed.
(B) First, the tool base is heated to 500 ° C. with a heater while the inside of the device is exhausted and kept in a vacuum, and then a DC bias voltage of −1000 V is applied to the tool base that rotates while rotating on the rotary table. Then, the surface of the tool substrate is bombard-cleaned with argon ions for 5 to 30 minutes.
(C) Next, nitrogen gas is introduced into the apparatus as a reaction gas to obtain the nitrogen pressure shown in Table 2, and the temperature of the tool substrate rotating while rotating on the rotary table is maintained within the temperature range shown in Table 2. At the same time, the DC bias voltage shown in Table 2 is applied, and the arc current shown in Table 2 is passed between the Al-Ti-Cr-B-W-Ag alloy target and the anode electrode to generate an arc discharge ( By depositing and forming Al, Ti, Cr, B, W, Ag) N layers, the coating tools of the present invention (hereinafter referred to as the tools of the present invention) 1 to 7 having the hard coating layer shown in Table 3 were produced.

For the (Al, Ti, Cr, B, W, Ag) N layers of the tools 1 to 7 of the present invention, the composition analysis of the cross section of each layer perpendicular to the surface of the tool substrate is performed by transmission electron microscopy-energy dispersive X-ray spectroscopy. (TEM-EDS) was used.
That is, the (Al, Ti, Cr, B, W, Ag) N layers of the tools 1 to 7 of the present invention are 0.01 μm or less with respect to the vertical cross section of the upper layer in an observation range of 20 μm in the direction parallel to the surface of the tool substrate. The spatial resolution of the elemental mapping was performed, and the composition of the coated (Al, Ti, Cr, B, W, Ag) N layer was measured.
Furthermore, the average layer thickness of the (Al, Ti, Cr, B, W, Ag) N layer was measured using a scanning electron microscope (SEM).
Table 3 shows each of these measured values.

Next, for the purpose of comparison, the AIP apparatus was used to form a vapor deposition on the surface of the tool substrate under the conditions shown in Table 4 in the same manner as in the steps (a) to (c) of Example 1. , Comparative coating tools (hereinafter referred to as comparative tools) 1 to 7 provided with N layers (Al, Ti, Cr, B, W, Ag) having the composition and the target average layer thickness shown in Table 5 were prepared.
Further, for reference, a conventional coating tool 1 having a hard coating layer (specifically, (Al, Ti, Cr, B) N layer) satisfying the component composition shown in Patent Document 1 (hereinafter, conventional coating tool 1). A conventional coating tool 2 (hereinafter referred to as a conventional coating tool 2) having a hard coating layer (specifically, (Al, Ti, Cr, B, W) N layer) satisfying the component composition shown in Patent Document 2 and the tool 1). Tool 2) was prepared by the arc ion plating method under the conditions shown in Table 4.

For the comparative tools 1 to 7, the composition of the (Al, Ti, Cr, B, W, Ag) N layer was analyzed in the same manner as in Example 1, and (Al, Ti, Cr, B, W) were analyzed. , Ag) The average thickness of the N layer was measured.
Also, for the conventional tools 1 and 2, the composition analysis of the hard coating layer and the measurement of the average layer thickness were performed.
Table 5 shows each of these values.

Then, the tools 1 to 7 of the present invention, the comparative tools 1 to 7, and the conventional tools 1 and 2 were subjected to a wet face milling cutter and a center cut cutting process test, which are a kind of intermittent cutting, and the damage state of the cutting edge was observed. ..

[Cutting test]
Cutting test: Wet face milling, center cut cutting,
Work material: JIS / Ti-6Al-4V alloy (60 types) Block material Width 60 mm, Length 250 mm,
Cutter diameter: 85 mm,
Cutting speed: 74 m / min. ,
Notch: 3 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 12 minutes,
Table 6 shows the results of the cutting test.

From the results shown in Table 6, the tools 1 to 7 of the present invention have a high Ti-based alloy because the hard coating layer composed of (Al, Ti, Cr, B, W, Ag) N layers has excellent lubricity. It exhibits excellent welding resistance and chipping resistance in efficient cutting, and also exhibits excellent cutting performance over a long period of use.
On the other hand, the comparative tools 1 to 7 and the conventional tools 1 and 2 have a short tool life due to welding and chipping due to insufficient lubricity of the hard coating layer.
In particular, the conventional tools 1 and 2 have reached the end of their life in a short time because the cutting resistance increases at the initial stage of cutting and a defect occurs.

The covering tool of the present invention exhibits excellent welding resistance and chipping resistance in high-efficiency cutting of difficult-to-cut materials such as Ti-based alloys and stainless steel, and can extend the service life. Of course, it can also be used for cutting of other work materials and cutting under other conditions.

Claims (2)

In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool substrate made of any of tungsten carbide-based cemented carbide, titanium nitride-based cermet, cubic boron nitride sintered body, and high-speed tool steel.
The hard coating layer is a composite nitride layer of Al, Ti, Cr, B, W, and Ag having an average layer thickness of 0.5 to 10 μm .
The composite nitride,
Composition formula: (Al _a Ti _b Cr _{(1- (a + b + c + d + e))} B _c W _d Ag _e ) N
When represented by, 0.40 ≦ a ≦ 0.85, 0.05 ≦ b ≦ 0.30, 0.005 <c ≦ 0.100, 0 <d ≦ 0.100, 0.005 ≦ e ≦ 0 A surface coating cutting tool comprising .050, (where a, b, c, d, e all indicate atomic ratios). The composition formula: (Al _a Ti _b Cr _{(1- (a + b + c + d + e))} B _c W _d Ag _e ) The Al content ratio a in N satisfies 0.55 ≦ a ≦ 0.68. The surface coating cutting tool according to claim 1.

Images