JP2010023118A - Surface-coated cutting tool exhibiting excellent self-lubricity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool exhibiting excellent abrasion resistance by making a hard coating layer exhibit excellent self-lubricity in cutting work of a material to be cut having high weldability. <P>SOLUTION: On a tool substrate surface of the surface-coated cutting tool, there are vapor-deposited a Ni carbonitride layer and a nitride layer satisfying 0.1≤X≤1.0, where X is an atomic ratio, when expressed in a composition formula: Ni(C<SB>1-X</SB>N<SB>X</SB>) though or not through a composite nitride-based hard coating layer of Al and Ti or a composite nitride-based hard coating layer of Al and Cr. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In particular, the present invention exhibits excellent self-lubricating properties even when a work material with high weldability, such as mild steel and stainless steel, is machined under high-speed cutting conditions with high heat generation. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent wear resistance over a long period of time.

  In general, for coated tools, throwaway inserts that can be used detachably attached to the tip of a cutting tool for turning and planing of various steel and cast iron, drilling of the work material, etc. Drills and miniature drills, and solid type end mills used for chamfering, grooving, shouldering, etc. of the work material, etc. A slow-away end mill tool that performs cutting work in the same manner as an end mill is known.

As a specific coated tool, for example, a hard film is formed on the surface of a tool base made of tungsten carbide group (hereinafter referred to as WC group) cemented carbide or titanium carbonitride group (hereinafter referred to as TiCN group) cermet. Is generally known to improve wear resistance and tool life of coated tools.
For example, a coated tool in which a composite nitride hard coating layer of Al and Ti is vapor-deposited on the surface of the tool base, and a coated tool in which a composite nitride hard coating layer of Al and Cr is vapor-deposited on the surface of the tool base. It is known that when used for cutting carbon steel or alloy steel, it exhibits excellent wear resistance.
In addition, a coated tool is also known that improves the lubricity of the coated tool by further forming a Ni oxide film on the composite nitride-based hard coating layer.
JP-A-7-300649 JP-A-8-209333 JP 2004-106183 A Japanese Patent Laying-Open No. 2005-330539 JP 2006-82209 A JP 2000-233324 A

  In recent years, the use of FA for cutting devices has been remarkable. On the other hand, there has been a strong demand for labor saving and energy saving and further cost reduction for cutting processing, and along with this, cutting processing tends to be further accelerated. In the case of a coated tool, there is no problem when it is used for cutting under normal conditions, but this is especially true for work materials with high weldability, such as mild steel and stainless steel, at high speed with high heat generation. When used for cutting, the hard coating layer is overheated by the high heat generated during cutting, resulting in insufficient high-temperature hardness and lubricity, and welding, resulting in reduced wear resistance and chipping. As a result, the service life is reached in a relatively short time.

In view of the above, the present inventors, from the above viewpoint, have a hard coating layer with excellent lubrication when cutting work materials such as soft steel and stainless steel that are likely to be welded under high-speed cutting conditions that generate high heat. As a result of conducting research while focusing on the above-mentioned conventional coated tools in order to develop coated tools that exhibit high performance and wear resistance,
(B) For example, an arc ion plating (AIP) apparatus having a structure shown in FIG. 1 (a) in a schematic plan view and in FIG. 1 (b) in a schematic front view is used. The substrate) is provided with a turntable for mounting, and a Ni carbonitride or nitride (hereinafter referred to as Ni (C, N)) layer forming cathode electrode is provided in the apparatus, and if necessary, for example, Al / Ti composite nitride (hereinafter referred to as (Al, Ti) N) hard coating layer (or Al and Cr composite nitride (hereinafter referred to as (Al, Cr) N) hard coating layer) (Forming) Cathode electrode (hereinafter referred to as an underlayer forming electrode) is provided, and the tool base is mounted in a ring shape on the tool base mounting rotary table. When rotating the rotary table In addition, an arc discharge is generated between the cathode electrode for forming the Ni (C, N) layer and the anode electrode while rotating the tool base itself for the purpose of uniforming the thickness of the hard coating layer to be formed. And a Ni (C, N) layer should be vapor-deposited on the tool base surface.

(B) A base layer made of (Al, Ti) N hard coating layer or (Al, Cr) N hard coating layer is interposed between the tool base surface and the Ni (C, N) layer. In some cases, an arc discharge is generated between the cathode electrode for forming the underlayer and the anode electrode to form an underlayer by vapor deposition, and then between the cathode electrode for forming the Ni (C, N) layer and the anode electrode. The arc discharge may be started.

(C) The Ni (C, N) layer formed by vapor deposition is a hard coating layer having a predetermined high-temperature hardness, and therefore exhibits a predetermined wear resistance when used for high-speed cutting. However, in addition to this, the Ni (C, N) layer is overheated by high heat generated during cutting, and a part of the Ni (C, N) layer is nickel oxide, nitride oxide, carbonate, carbonitride (hereinafter referred to as “carbonitrate”). These are collectively referred to simply as NiO.) Since this NiO has self-lubricating properties, in high-speed cutting of work materials with high weldability, lubricity with the work materials Because it has the effect of increasing welding and suppressing welding, it does not cause welding, chipping, uneven wear, etc. even when a highly weldable work material such as stainless steel is machined under high-speed cutting conditions that generate high heat. It will provide excellent wear resistance over a long period of time. .

(D) Further, the Ni (C, N) layer is vapor-deposited on the surface of the tool base through an underlayer composed of an (Al, Ti) N-based hard coating layer or an (Al, Cr) N-based hard coating layer. In this case, Al, which is a constituent component of the underlayer, improves the high temperature hardness, heat resistance and oxidation resistance, and the Ti and Cr improve the high temperature strength. The hard coating layer composed of the (C, N) layer not only further improves cutting tool properties such as chipping resistance and wear resistance, but also exhibits excellent lubricity even in cutting under high temperature conditions. To exhibit excellent wear resistance over a long period of time without causing chipping or uneven wear.
The findings shown in (a) to (d) above have been obtained.

This invention has been made based on the above findings,
“(1) In a surface-coated cutting tool in which a hard coating layer is deposited on the surface of a tool base composed of a tungsten carbide group (WC group) cemented carbide or a titanium carbonitride group (TiCN group) cermet,
At least one layer of the hard coating layer is
Composition formula: Ni (C1 _{- XNx} )
In this case, it is characterized by being a Ni carbonitride layer and a nitride layer (Ni (C, N) layer) satisfying 0.1 ≦ X ≦ 1.0 (where X is an atomic ratio). Self-lubricating surface coated cutting tool.
(2) Al / Ti composite nitride ((Al, Ti) N) system between the surface of the tool base and the Ni carbonitride layer and nitride layer (Ni (C, N) layer) The self-lubricating surface-coated cutting tool according to (1), wherein a hard coating layer or a composite nitride ((Al, Cr) N) hard coating layer of Al and Cr is interposed. "
It has the characteristics.

  Next, the coated tool of the present invention will be described in detail.

Ni (C, N) layer;
The method of forming the Ni (C, N) layer itself is not particularly limited. For example, the deposition amount is set in a mixed atmosphere gas of nitrogen gas and methane gas with metal Ni as a target under the following conditions. By performing arc ion plating while adjusting the thickness, a Ni (C, N) layer having a predetermined thickness can be formed by vapor deposition.
Deposition conditions:
Reaction gas composition (volume%): CH ₄ 0-90%, balance N ₂
Reaction gas pressure: 1.33-13.3 Pa,
Bias voltage: 0--500V, period 1 kHz-500 kHz pulse bias,
The deposited Ni (C, N) layer has excellent lubricity and high temperature hardness.
Composition formula: Ni (C1 _{- XNx} )
When the value of X is less than 0.1, the effect of improving lubricity and the effect of improving welding resistance are reduced, so 0.1 ≦ X ≦ 1.0 (where X is an atomic ratio) It is necessary to have a composition that satisfies
Therefore, a coated tool in which a Ni (C, N) layer is vapor-deposited as a hard coating layer can be used even when a work material with high weldability such as mild steel or stainless steel is cut under high-speed conditions. N) The layer has excellent high-temperature hardness and at the same time has excellent self-lubricity, thereby preventing the occurrence of welding due to high heat, chipping, chipping, peeling, etc., and at the same time having a hard coating layer Abrasion resistance can be maintained over a long period of time.
As for the layer thickness of the Ni (C, N) layer, if it is too thin, sufficient lubricity cannot be exhibited over a long period of use. On the other hand, if it is too thick, chipping tends to occur. Moreover, since abrasion resistance also comes to show a decreasing tendency, it is desirable that it is 1.0-10.0 micrometers.

An underlayer comprising an (Al, Ti) N-based hard coating layer or an (Al, Cr) N-based hard coating layer;
By interposing and forming a base layer made of an (Al, Ti) N-based hard coating layer or an (Al, Cr) N-based hard coating layer between the surface of the tool base and the Ni (C, N) layer. Further, the wear resistance of the coated tool can be further improved. In particular, in the hard coating layer, it is well known that Al as its component improves high temperature hardness, heat resistance and oxidation resistance, and the Ti component and Cr component improve high temperature strength. .
As a specific (Al, Ti) N-based hard coating layer or (Al, Cr) N-based hard coating layer, various known hard films can be used. For example, (Al, Ti) Examples of the N layer, the (Al, Cr) N layer, and a hard film containing components such as IVa group, Va group, VIa group element, Si, B, etc. as the additive component M to these layers. it can.

In the coated tool of the present invention, the Ni (C, N) layer has excellent high-temperature hardness, and further forms NiO having excellent self-lubricating property at the time of cutting, thereby improving lubricity. Even when work materials with high weldability such as stainless steel are processed under high-speed cutting conditions with particularly large heat generation, they exhibit excellent chipping resistance and welding resistance, and exhibit excellent wear resistance. .
Further, in a coated tool in which an (Al, Ti) N-based hard coating layer or an (Al, Cr) N-based hard coating layer is interposed between the tool base surface and the Ni (C, N) layer as an underlayer. The Ni (C, N) layer exhibits excellent high-temperature hardness and lubricity, and the underlayer has excellent high-temperature hardness, high-temperature strength, heat resistance, oxidation resistance, etc. As a whole layer, it exhibits superior high-temperature hardness, high-temperature strength, heat resistance, oxidation resistance, and lubricity, and it is possible to cut work materials with high weldability such as mild steel and stainless steel, especially at high speeds with large heat generation. Even when processed under the conditions, it exhibits excellent chipping resistance and welding resistance, exhibits no uneven wear, and exhibits even better wear resistance over a long period of time.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders are blended in the composition shown in Table 1, wet mixed by a ball mill for 72 hours, dried, and then pressed into a green compact at a pressure of 100 MPa. Medium, sintered at 1400 ° C for 1 hour, after sintering, WC-based carbide with honing of R: 0.03 on the cutting edge and chip shape of ISO standard CNMG120408 Alloy tool bases A1 to A10 were formed.

In addition, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, mix these raw material powders into the composition shown in Table 2, wet mix for 24 hours with a ball mill, dry, and press-mold into green compact at 100 MPa pressure The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to meet ISO standards / Tool bases B1 to B6 made of TiCN base cermet having a chip shape of CNMG120408 were formed.

Next, each of the tool bases A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, and mounted on the rotary table of the arc ion plating apparatus shown in FIG. As an electrode for forming a base layer of a plating apparatus, alloys 1 to 10 (referred to as cathodes 1 to 10) having various compositions shown in Table 3 are mounted, and metal Ni is used as an electrode for forming a Ni (C, N) layer. Furthermore, metal Ti is also attached as a cathode electrode for bombard cleaning, and the inside of the apparatus is first heated to 500 ° C. with a heater while maintaining a vacuum of 0.5 Pa or less. A DC bias voltage of −1000 V is applied to the rotating tool base while rotating above, and the metal electrode Ti between the bombard cleaning cathode electrode and the anode electrode is applied. By flowing a 100A current to generate arc discharge, a tool substrate surface was washed Ti bombardment with,
(B) Next, when forming the base layer, nitrogen gas or a mixed gas of nitrogen gas and methane gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 3 Pa and rotate on the rotary table. While applying a DC bias voltage of −100 V to the rotating tool base and causing a current of 100 A to flow between the base layer forming electrode and the anode electrode, arc discharge is generated, and predetermined components shown in Tables 4 and 5 Composition, undercoat layer with a predetermined target layer thickness is formed by vapor deposition,
(C) Next, a mixed gas of nitrogen gas and methane gas is introduced as an atmosphere in the apparatus to maintain a reaction atmosphere of 3 Pa, and a tool base that rotates while rotating on the rotary table has a period of 20 kHz, 0 to −100 V. The DC pulse bias voltage is applied to cause a 90 A current to flow between the metal Ni as the Ni (C, N) layer forming electrode and the anode electrode to generate an arc discharge. By vapor-depositing a Ni (C, N) layer having a predetermined composition,
To ISO / CNMG120408 having a Ni (C, N) layer (directly through or without (Al, Cr) N-based hard coating layer or (Al, Cr) N-based hard coating layer) on the tool base surface. The present invention coated tools 1 to 16 (hereinafter referred to as the present coated chips 1 to 16) each having a defined throwaway tip shape were manufactured.

For the purpose of comparison, among these tool bases A1 to A10 and B1 to B6, the tool bases A1 to A5 and B1 to B3 are ultrasonically cleaned in acetone and dried, respectively, in the arc shown in FIG. The ion plating apparatus was charged, cathodes 1 to 10 shown in Table 3 were attached as cathode electrodes (evaporation source), metal Ni was attached as a cathode electrode for Ni oxide film formation (evaporation source), A metallic Ti cathode electrode for bombard cleaning is also mounted, and the inside of the apparatus is evacuated and kept at a vacuum of 0.5 Pa or less, and the inside of the apparatus is heated to 500 ° C. with a heater, and then a DC bias voltage of −1000 V is applied to the tool base. Is applied, and a current of 100 A is caused to flow between the metal Ti of the cathode electrode for bombard cleaning and the anode electrode to generate an arc discharge, thereby providing a tool base. The surface was washed Ti bombardment,
Next, nitrogen gas is introduced into the apparatus as a reaction gas to make a reaction atmosphere of 2 Pa, and the bias voltage applied to the tool base is lowered to −100 V, so that the cathodes 1 to 5 of the present invention and the anode electrode are interposed. A hard layer having a target composition and a target layer thickness shown in Tables 6 and 7 is formed on the surface of each of the tool bases A1 to A5 and B1 to B3 by causing an electric current of 90 A to flow. Corresponding to the underlying layer)
Thereafter, an atmosphere gas composed of oxygen is introduced as a reaction gas into the apparatus to obtain a reaction atmosphere of 2 Pa, and a DC bias voltage of −100 V is applied to the tool base that rotates while rotating on the rotary table, An arc discharge is generated by passing a current of 90 A between the cathode electrode and the anode electrode for forming the Ni oxide film, and a Ni oxide film layer having a predetermined thickness shown in Tables 6 and 7 is formed on the hard layer by vapor deposition. By doing
Similarly, conventional coated tools 1 to 5 and 11 to 13 (hereinafter referred to as conventional coated chips 1 to 5 and 11 to 13) each having a throwaway tip shape were manufactured.

For comparison purposes, among these tool bases A1 to A10 and B1 to B6, the tool bases A6 to A10 and B4 to B6 are ultrasonically cleaned in acetone and dried, as shown in FIG. Installed in the arc ion plating apparatus, mounted with cathodes 1-10 shown in Table 3, and also mounted with a metallic Ti cathode electrode for bombard cleaning, and evacuated the apparatus and kept at a vacuum of 0.5 Pa or less. However, after heating the inside of the apparatus to 500 ° C. with a heater, a DC bias voltage of −1000 V was applied to the tool base, and a current of 100 A was passed between the metal Ti and the anode electrode of the cathode electrode for bombard cleaning. Arc discharge is generated, and the tool substrate surface is cleaned with Ti bombardment,
Next, nitrogen gas is introduced into the apparatus as a reaction gas to make a reaction atmosphere of 2 Pa, and the bias voltage applied to the tool base is lowered to −100 V, so that the cathodes 1 to 5 of the present invention and the anode electrode are interposed. A hard layer having a target composition and a target layer thickness shown in Tables 6 and 7 is formed on the surface of each of the tool bases A6 to A10 and B4 to B6. By vapor deposition)
Similarly, conventional coated tools 6 to 10 and 14 to 16 having a throwaway tip shape (hereinafter referred to as conventional coated chips 6 to 10 and 14 to 16) were produced.

Next, in the state where each of the above-mentioned various coated chips is screwed to the tip of the tool steel tool with a fixing jig, the present coated chips 1-16 and the conventional coated chips 1-16,
Work material: JIS / SUS347 round bar,
Cutting speed: 160 m / min. ,
Cutting depth: 2.0 mm,
Feed: 0.5 mm / rev. ,
Cutting time: 5 minutes,
Austenitic stainless steel dry high-speed cutting test under normal conditions (cutting condition A) (normal cutting speed is 100 m / min.),
Work material: JIS / S22C round bar,
Cutting speed: 280 m / min. ,
Cutting depth: 2.0 mm,
Feed: 0.5 mm / rev. ,
Cutting time: 5 minutes,
Dry high-speed cutting test of mild steel under the conditions (cutting condition B) (normal cutting speed is 250 m / min.),
Work material: JIS / SNCM220 round bar,
Cutting speed: 190 m / min. ,
Cutting depth: 3.0 mm,
Feed: 0.5 mm / rev. ,
Cutting time: 4 minutes,
Dry high-speed cutting test of alloy steel under the following conditions (cutting condition B) (normal cutting speed is 130 m / min.),
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 8.

As a result, the (Al, Ti) N-based hard coating layer, (Al, Cr) N-based hard coating layer, and Ni (C) constituting the hard coating layers of the present coated chips 1 to 16 as the present coated tool are obtained. , N) The composition of each component of the layer was measured by energy dispersive X-ray analysis using a transmission electron microscope, and showed substantially the same composition as the target composition.
Moreover, when the composition of each layer constituting the hard coating layer of the conventional coated chips 1 to 16 as the conventional coated tool was measured by an energy dispersive X-ray analysis method using a transmission electron microscope, the target composition and each of the layers were substantially equal to each other. Showed the same composition.

From the results shown in Tables 4 to 8, the coated tool of the present invention is a case where a work material having high weldability such as mild steel and stainless steel is used for cutting under high-speed conditions accompanied by high heat generation. However, since at least one layer of the hard coating layer is made of a Ni (C, N) layer having excellent high temperature hardness and lubricity, there is no occurrence of welding, chipping and uneven wear, and it has been excellent over a long period of time. In contrast to the wear resistance, the conventional coated tools have high heat generation during high-speed cutting, especially due to insufficient lubricity, resulting in welding, uneven wear, and chipping. It is clear that the service life is reached in a relatively short time.
In addition, not only the coated chip but also a coated end mill and a coated drill were prepared and the same cutting test was performed. As a result, the same results as the coated chip were obtained for the coated end mill and the coated drill.

  As described above, the coated tool of the present invention can be used not only for cutting of general steel and ordinary cast iron, but also for high-speed cutting with high heat generation of work materials with high weldability such as mild steel and stainless steel. Even when it is used, it exhibits excellent chipping resistance and wear resistance over a long period of time and exhibits excellent cutting performance. Therefore, FA of the cutting device, labor saving and energy saving of cutting processing, Furthermore, it can cope with cost reduction sufficiently satisfactorily.

It is a schematic plan view of the arc ion plating apparatus used for forming a hard coating layer. It is the schematic of the arc ion plating apparatus used in order to form the hard coating layer of the conventional coating | coated chips 6-10 and 14-16.

Claims (2)

In a surface-coated cutting tool in which a hard coating layer is deposited on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
At least one layer of the hard coating layer is
Composition formula: Ni (C1 _{- XNx} )
A self-lubricating surface-coated cutting tool characterized by being a Ni carbonitride layer and a nitride layer satisfying 0.1 ≦ X ≦ 1.0 (where X is an atomic ratio).   An Al and Ti composite nitride hard coating layer or an Al and Cr composite nitride hard coating layer is interposed between the surface of the tool base and the Ni carbonitride layer and nitride layer. The self-lubricating surface-coated cutting tool according to claim 1, wherein

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