JP2008137129A - Surface coated cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cutting tool, in which a hard coating layer can show excellent wear resistance in the high speed cutting of a difficult-to-cut material, such as stainless steel and nodular graphite cast iron. <P>SOLUTION: The surface coated cutting tool has a lower layer composed of a Ti compound layer and an upper layer composed of an Al<SB>2</SB>O<SB>3</SB>layer on the surface of the base body of the tool. An outermost layer provided on the Al<SB>2</SB>O<SB>3</SB>layer within the flank region of the tool is composed of a composite nitride layer of Ti, Al, (and M) formed by a PVD process so as to satisfy the following condition: (Ti<SB>1-X-Y</SB>Al<SB>X</SB>M<SB>Y</SB>)N, where 0.30≤X≤0.70, Y=0 or 0.01≤Y≤0.10, by atomic ratio, and M represents additional components of one or more elements selected from Si, Cr, V, Y, and B. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent wear resistance with a hard coating layer in high-speed cutting of difficult-to-cut materials such as stainless steel and ductile cast iron.

Conventionally, in general, on the entire rake face and flank face including the cutting edge ridge line portion of the tool base made of tungsten carbide (hereinafter referred to as WC) based cemented carbide,
As a lower layer, a titanium carbide (hereinafter referred to as TiC) layer, a titanium nitride (hereinafter also referred to as TiN) layer, a titanium carbonitride (hereinafter referred to as TiCN) layer, a titanium carbonate (hereinafter referred to as TiCO) layer And a Ti compound layer comprising one or more of titanium carbonitride oxide (hereinafter referred to as TiCNO) layers and having an overall average layer thickness of 3 to 20 μm,
As an upper layer, an aluminum oxide layer (hereinafter referred to as an α-type Al ₂ O ₃ layer) having an average layer thickness of 1 to 15 μm and having an α-type crystal structure in a state of chemical vapor deposition is provided.
In addition, on the surface of the Al ₂ O ₃ layer on the flank of the tool, a usage status display made of an easily wearable material such as TiN is used to identify whether the coated tool is unused or used. It is known to form the layer by chemical vapor deposition.

In the above-described coated tool, the constituent layer of the hard coating layer generally has a granular crystal structure, and the TiCN layer constituting the Ti compound layer, which is the lower layer, is used for the purpose of improving the strength of the layer itself. It is also known that a vapor deposition apparatus uses a mixed gas containing organic carbonitrides as a reaction gas, and is formed by chemical vapor deposition at an intermediate temperature range of 700 to 950 ° C. to have a vertically grown crystal structure. ing.
It is also known that the surface of the α-type Al ₂ O ₃ layer (upper layer) constituting the hard coating layer of the above-mentioned coated tool is smoothed by wet blasting or the like for the purpose of improving cutting performance. .
JP 2002-144108 A Japanese Patent Laid-Open No. 6-8010

  In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting work, and along with this, cutting work tends to be further accelerated. For coated tools, there is no problem when this is used for cutting under normal processing conditions such as steel and cast iron, but when this is used for high-speed cutting of difficult-to-cut materials such as stainless steel and ductile cast iron. In this case, the progress of wear is promoted by high heat generated during cutting, and even if a usage state display layer such as TiN is formed on the flank of the tool by chemical vapor deposition as in the conventional coated tool, the usage state display layer Since it is formed from an easily wearable material and is merely a layer for identifying the use state, there is almost no effect in improving the wear resistance. As a result, the service life is reached in a relatively short time.

Therefore, the present inventors conducted research to improve the wear resistance of the hard coating layer of the conventional coated tool,
(A) In place of the use state display layer formed by chemical vapor deposition in the above-mentioned conventional coated tool on the surface of the α-type Al ₂ O ₃ layer that is the upper layer of the hard coating layer on the flank of the coated tool, Ti and Al Or a composite nitride layer of Ti, Al, and M (wherein M represents one or more of Si, Cr, V, Y, and B) (hereinafter collectively referred to as (Ti , Al, M) N layer) is formed by physical vapor deposition and the outermost layer of 1 to 10 μm is formed, the (Ti, Al, M) N layer is a hard film and has excellent lubricity. Also, because it is a layer in which compressive stress remains, it exhibits excellent wear resistance even in high-speed cutting of difficult-to-cut materials that generate high heat.

(B) In forming the (Ti, Al, M) N layer as the outermost layer by physical vapor deposition on the surface of the α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer in the coated tool flank region. On the α-type Al ₂ O ₃ layer, a Ti compound layer (Ti carbide layer, nitride layer, carbonitride layer, oxide layer, carbonate layer and carbonitride) having a total average layer thickness of 0.2 to 2 μm As an intermediate layer of one or more of the oxide layers), the outermost layer can be easily formed by physical vapor deposition on the surface, and between the upper layer and the outermost layer. Bond strength is improved.
The research results shown in (a) and (b) have been obtained.

This invention was made based on the above research results,
“(1) On the surface of the tool base made of tungsten carbide base cemented carbide,
(A) The entire 3-20 μm formed by chemical vapor deposition, consisting of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer. A lower layer comprising a Ti compound layer having an average layer thickness,
(B) An aluminum oxide layer provided on the lower layer of (a) above, having an α-type crystal structure in a chemical vapor deposited state and having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition. Upper layer,
In the surface-coated cutting tool in which the hard coating layer composed of the above (a) and (b) is formed by vapor deposition,
On the upper layer composed of the aluminum oxide layer in the flank region of the surface-coated cutting tool,
(C) having an average layer thickness of 1 to 10 μm, and
Outermost layer composed of a composite nitride layer of Ti and Al formed by physical vapor deposition satisfying the composition formula: (Ti _1-X Al _X ) N (wherein the atomic ratio is 0.30 ≦ X ≦ 0.70) A surface-coated cutting tool characterized by comprising:
(2) In the surface-coated cutting tool of (1),
The outermost layer of (c) is
_{Formula: (Ti 1-X-Y} Al X M Y) N ( provided that an atomic ratio is 0.30 ≦ X ≦ 0.70,0.01 ≦ Y ≦ 0.10, Further, M, A composite nitride layer of Ti, Al, and M formed by physical vapor deposition satisfying one or more additive components selected from Si, Cr, V, Y, and B);
The surface-coated cutting tool according to (1) above, wherein
(3) In the surface-coated cutting tool according to (1) and (2),
(D) 0 consisting of one or more of Ti carbide layer, nitride layer, carbonitride layer, oxide layer, carbonate layer and carbonitride layer, and formed by chemical vapor deposition An intermediate layer comprising a Ti compound layer having an overall average layer thickness of 2 to 2 μm;
The surface-coated cutting tool according to any one of (1) and (2), wherein is interposed between the upper layer and the outermost layer. "
It has the characteristics.

Hereinafter, the hard coating layer (lower layer, upper layer, intermediate layer, outermost layer) of the present invention will be described in detail.
(1) Lower layer (Ti compound layer)
The Ti compound layer exists as a lower layer of the α-type Al ₂ O ₃ layer, contributes to improving the high-temperature strength of the hard coating layer by its excellent high-temperature strength, and includes the tool base and the α-type Al ₂ O ₃ layer. However, if the average layer thickness is less than 3 μm, the above-mentioned effect cannot be fully exerted, while the hard coating layer has an effect of improving the adhesion of the hard coating layer to the tool substrate. When the average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation in high-speed cutting with high heat generation, and this causes uneven wear. Therefore, the average layer thickness is set to 3 to 20 μm.

(2) Upper layer (α-type Al ₂ O ₃ layer)
The upper layer composed of α-type Al ₂ O ₃ formed by chemical vapor deposition has excellent high-temperature hardness and heat resistance and contributes to the wear resistance and chipping resistance of the coated tool, but its average layer thickness is 1 μm. If it is less than 1, the desired excellent cutting performance cannot be exhibited over a long period of time. On the other hand, if the average layer thickness exceeds 15 μm, chipping tends to occur. Was determined to be 1 to 15 μm.

(3) Intermediate layer (Ti compound layer)
A normal chemical vapor deposition apparatus is used on the surface of the upper layer (α-type Al ₂ O ₃ layer) formed by chemical vapor deposition on the entire surface of the tool base, and the normal condition (for example, the conditions shown in Table 2) is 0. Intermediate layers (Ti carbide (TiC) layer, nitride (TiN) layer, carbonitride (TiCN) layer, oxide (TiO) layer, carbonate (TiCO) layer and carbon) with an overall average layer thickness of 2-2 μm Ti compound layer consisting of one or more of the nitride oxide (TiCNO) layers is formed by vapor deposition, and the intermediate layer is interposed between the upper layer and the outermost layer, so that the upper layer and the outermost layer are disposed. Interlayer adhesion and bonding strength can be improved.
If the total average layer thickness of the intermediate layer is less than 0.2 μm, it cannot be expected to improve the adhesion and bonding strength between the upper layer and the outermost layer, and if the thickness exceeds 2 μm, the hard coating layer Since the high-temperature hardness decreases and the wear resistance deteriorates, the overall average layer thickness is determined to be 0.2 to 2 μm.

(4) Outermost layer ((Ti, Al, M) N layer)
(A) On the intermediate layer in the coated tool flank region, for example, by the physical vapor deposition apparatus shown in the schematic explanatory diagram of FIG. 1, the target compositions and target layer thicknesses (Ti, Al, M) The N layer is formed by physical vapor deposition with an average layer thickness of 1 to 10 μm, and the composite nitride layer of Ti and Al (and M) constituting the outermost layer is hard and excellent in lubricity, Since it is a layer having residual compressive stress, it exhibits excellent wear resistance in high-speed cutting of difficult-to-cut materials. That is, the Al component that is a constituent component of the (Ti, Al, M) N layer improves the high temperature hardness and heat resistance of the hard coating layer, and the Ti component has the effect of improving the high temperature strength. The outermost layer improves the chipping resistance and wear resistance of the hard coating layer formed in the flank area of the coated tool. Further, when component M is contained in the composite nitride layer, Si as additive component M contributes to improvement of heat resistance and heat plastic deformation of the layer, and Cr contributes to improvement of heat resistance and high temperature strength. , V contributes to improvement of lubricity, Y contributes to improvement of high-temperature oxidation resistance, B further contributes to improvement of thermal conductivity, and any additive component has the effect of improving the characteristics of the outermost layer. Therefore, one or more of Si, Cr, V, Y, and B is added as a constituent component of the outermost layer as the additive component M according to desired characteristics required for the coated tool flank region. .
And if the X value indicating the proportion of Al is less than 0.30 in the proportion of the total amount of Ti and M (atomic ratio, the same shall apply hereinafter), the predetermined high temperature hardness and heat resistance cannot be ensured. This causes a decrease in wear resistance. On the other hand, when the X value indicating the Al ratio exceeds 0.70, the Ti ratio is relatively less than 0.30, and high-speed cutting with high heat generation is caused. Since the high-temperature strength required in the above cannot be ensured and it becomes difficult to prevent the occurrence of chipping, the X value is determined to be 0.30 to 0.70.
In addition, Si, Cr, V, Y, and B as the additive component M included each component element when the total content ratio of each component was less than 0.01 in the total amount of Ti and Al. On the other hand, if the total content ratio of each component exceeds 0.1 in the total content of Ti and Al, the content ratio of Ti and Al is relatively decreased. Therefore, in order to be unable to maintain the high-temperature hardness, heat resistance, and high-temperature strength of the upper layer required for high-speed cutting, the Y value representing the total content of the additive component M was determined to be 0.01 to 0.10.
And, when the average layer thickness is less than 1 μm, the outermost layer is insufficient to exhibit its excellent properties (high temperature hardness, high temperature strength, heat resistance, etc.) over a long period of time, When the average layer thickness exceeds 10 μm, chipping is likely to occur during high-speed cutting, so the average layer thickness of the upper layer is set to 1 to 10 μm.

(B) A polishing liquid in which 15 to 60% by mass of Al ₂ O ₃ fine particles are blended in the rake face region of the tool base on which the outermost layer is vapor-deposited, for example, as a spraying abrasive in the total amount with water. The surface of the α-type Al ₂ O ₃ layer on the rake face can be smoothed by removing the intermediate layer and the outermost layer provided in the rake face region with a wet brass or the like. The surface roughness of the α-type Al ₂ O ₃ layer, which is a hard coating layer in the surface area, is extremely small, and the tensile residual stress of the α-type Al ₂ O ₃ layer is reduced, resulting in chipping resistance of the rake face. , Wear resistance is improved.

(C) In addition, the surface smoothening of the rake face is not only performed with the outermost layer removal (including the intermediate layer) but also directly with the α-type Al ₂ without forming the outermost layer (including the intermediate layer) in the rake face region. Of course, it can be performed on the O ₃ layer. Depending on which process is performed, there is no influence on the chipping resistance, wear resistance, etc. of the obtained coated tool. Surface smoothing and tensile residual stress reduction treatment for the α-type Al ₂ O ₃ layer on the rake face is performed by dry or wet blasting using a grindstone, nylon brush, SiC, ZrO ₂ particles, etc. as media. It is also possible to use a wet blasting process.

The coated tool of the present invention has an (Ti, Al) layer on the α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer in the tool flank region, via an intermediate layer made of a Ti compound layer as necessary. Since the outermost layer composed of an Al, M) N layer is formed by physical vapor deposition, it has excellent chipping resistance and wear resistance. Furthermore, α-type Al ₂ constituting the upper layer of the hard coating layer in the tool rake face region The O ₃ layer is excellent in chipping resistance because its tensile residual stress is reduced and its surface is smoothed. Therefore, the coated tool of the present invention exhibits excellent chipping resistance and wear resistance as a whole even when used for high-speed cutting of difficult-to-cut materials such as stainless steel and ductile cast iron. This makes it possible to further extend the service life.

  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 were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. Then, the green compact was vacuum sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour, and after sintering, the cutting edge portion was R: 0.03 honed By processing, WC based cemented carbide tool bases A to D having a throwaway tip shape specified in ISO / CNMG120408 are manufactured, and after sintering, the width of the cutting edge portion is 0.15 Tool bases C to F made of WC-base cemented carbide having a throwaway tip shape defined in ISO / SEEN1203AFSN1 were manufactured by processing R: 0.03 mm on Chamfor Honing with an angle of 20 mm and an angle of 20 degrees. .

Then, each of these tool bases A to F is charged into a normal chemical vapor deposition apparatus,
First, Table 2 (l-TiCN in Table 2 indicates the conditions for forming a TiCN layer having a vertically grown crystal structure described in JP-A-6-8010, and other than that, a normal granular crystal structure is shown. The Ti compound layer and the α-type Al ₂ O ₃ layer having the target layer thicknesses shown in Table 3 and Table 4 are deposited as the lower layer and the upper layer of the hard coating layer under the conditions shown in FIG. Forming,
Then, under the conditions shown in Table 2, the Ti compound layer having the target layer thickness shown in Tables 3 and 4 is also vapor-deposited as an intermediate layer over the entire flank area and rake face area.
Subsequently, the tool base is inserted into the arc ion plating apparatus schematically shown in FIG. 1, nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 4 Pa, and −100 V is applied to the tool base. A direct current bias voltage is applied, and an arc discharge is generated by flowing a current of 120 A between the Ti—Al—M alloy for forming the outermost layer of the cathode electrode and the anode electrode, and on the intermediate layer of the tool base, The outermost layer composed of (Ti, Al, M) N layers having the target composition and target layer thickness shown in Tables 3 and 4 is formed by physical vapor deposition with an average layer thickness of 1 to 10 μm.
Subsequently, only the rake face region of the tool base was mixed with 35% by mass of the Al ₂ O ₃ fine particles having a particle diameter of 30 to 60 μm as a spraying abrasive in the total amount with water, and 0.2 MPa. Wet blasting with pressure and smoothing to a surface roughness of about 0.13 μm with Ra, and simultaneously reducing the tensile residual stress of the α-type Al ₂ O ₃ layer of the rake face, 24 were produced respectively.

For the purpose of comparison, as shown in Table 5, it is the same as the coated tool of the present invention except that a use state display layer composed of a TiN layer is formed on the α-type Al ₂ O ₃ layer in the flank region by chemical vapor deposition. Conventionally, the conventional coated tools 1 to 12 were manufactured under the conditions. The formation of the usage state display layer made of the TiN layer was the same as the formation conditions of the intermediate layer TiN shown in Table 2.
In addition, after forming the use state indicating layer composed of the TiN layer, the rake face of the conventional coated tools 1 to 12 is subjected to wet blasting under the same conditions as in the case of the coated tools 1 to 24 of the present invention, thereby smoothing the surface. And to reduce the tensile residual stress.

  When the composition of each layer of the hard coating layers of the present invention coated tools 1 to 24 and the conventional coated tools 1 to 12 was measured with an Auger spectroscopic analyzer in the thickness direction, each was substantially the same as the target composition. The composition was further measured, and the thickness of each layer was measured using a scanning electron microscope (longitudinal section measurement). The average layer thickness (average value of five-point measurement) was substantially the same as the target layer thickness. Indicated.

Next, of the present invention coated tools 1 to 24 and the conventional coated tools 1 to 12, the present coated tools 1 to 8, 13 to 20 and the conventional coated tools 1 to 8 are turned according to the cutting conditions A and B. A machining test was carried out, and the milling test was carried out under the cutting condition C for the inventive coated tools 5-12, 17-24 and the conventional coated tools 5-12.
[Cutting conditions A]
Work material: JIS / FCD450 round bar,
Cutting speed: 450 m / min. ,
Cutting depth: 2.0 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 10 minutes,
Continuous wet high speed cutting test of ductile cast iron under the conditions of (normal cutting speed is 250 m / min.),
[Cutting conditions B]
Work material: JIS / SUS316 round bar,
Cutting speed: 400 m / min. ,
Cutting depth: 1.5 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 8 minutes,
Continuous dry high-speed cutting test of stainless steel under the conditions of (normal cutting speed is 200 m / min.),
[Cutting conditions C]
Work material: Block material of JIS / FCD700,
Cutting speed: 300 m / min,
Cutting depth: 2.0 mm,
Single blade feed rate: 0.2 mm / rev. ,
Cutting time: 10 minutes,
Continuous wet high-speed cutting test of ductile cast iron under the conditions (normal cutting speed is 200 m / min).
The flank wear width of the cutting edge in each of the above cutting tests was measured, and the measurement results are shown in Tables 6 and 7.

From the results shown in Tables 3 to 7, the coated tools 1 to 24 of the present invention are provided with an outermost layer excellent in chipping resistance and wear resistance in the flank region, and, if necessary, Ti By providing the outermost layer through an intermediate layer made of a compound layer, the bonding strength between the upper layer and the outermost layer is increased, and if necessary, the α-type Al ₂ O ₃ layer in the rake face region is smoothed. By reducing the tensile residual stress, the hard coating layer has excellent chipping resistance and wear resistance in high-speed cutting with high heat generation of difficult-to-cut materials such as stainless steel and ductile cast iron. While exhibiting excellent cutting performance, a conventional coated tool 1 in which a use state indicating layer composed of a TiN layer or the like is formed by chemical vapor deposition on the upper layer (α-type Al ₂ O ₃ layer) in the flank region. 12, high speed of difficult-to-cut materials In cutting machining, since wear resistance of the hard coating layer is poor, it is clear that lead to a relatively short time service life.

  As described above, the coated tool of the present invention is not only for cutting under normal conditions such as various types of steel, stainless steel and cast iron, but particularly difficult-to-cut materials such as stainless steel and ductile cast iron with high heat generation. Even under high-speed cutting conditions, it exhibits excellent chipping resistance and wear resistance, and exhibits excellent cutting performance over a long period of time. Furthermore, it can cope with cost reduction sufficiently satisfactorily.

It is a schematic explanatory drawing of an arc ion plating apparatus.

Claims (3)

On the surface of the tool base made of tungsten carbide base cemented carbide,
(A) The entire 3-20 μm formed by chemical vapor deposition, consisting of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer. A lower layer comprising a Ti compound layer having an average layer thickness,
(B) An aluminum oxide layer provided on the lower layer of (a) above, having an α-type crystal structure in a chemical vapor deposited state and having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition. Upper layer,
In the surface-coated cutting tool in which the hard coating layer composed of the above (a) and (b) is formed by vapor deposition,
On the upper layer composed of the aluminum oxide layer in the flank region of the surface-coated cutting tool,
(C) having an average layer thickness of 1 to 10 μm, and
Outermost layer composed of a composite nitride layer of Ti and Al formed by physical vapor deposition satisfying the composition formula: (Ti _1-X Al _X ) N (wherein the atomic ratio is 0.30 ≦ X ≦ 0.70) A surface-coated cutting tool characterized by comprising: The surface-coated cutting tool according to claim 1,
The outermost layer of (c) is
_{Formula: (Ti 1-X-Y} Al X M Y) N ( provided that an atomic ratio is 0.30 ≦ X ≦ 0.70,0.01 ≦ Y ≦ 0.10, Further, M, A composite nitride layer of Ti, Al, and M formed by physical vapor deposition satisfying one or more additive components selected from Si, Cr, V, Y, and B);
The surface-coated cutting tool according to claim 1. The surface-coated cutting tool according to claim 1 or 2,
(D) 0 consisting of one or more of Ti carbide layer, nitride layer, carbonitride layer, oxide layer, carbonate layer and carbonitride layer, and formed by chemical vapor deposition An intermediate layer comprising a Ti compound layer having an overall average layer thickness of 2 to 2 μm;
The surface-coated cutting tool according to claim 1, wherein is interposed between the upper layer and the outermost layer.

Images