JP2006082137A - Cutting tool and tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool high in adhesion of a base material and a covering layer formed on its surface, having excellent abrasion resistance and constituted by forming the covering layer on a surface of the base material with silicon nitride as a main component. <P>SOLUTION: This cutting tool constitutes its characteristic feature of having the cutting tool constituted by forming the covering layer on the surface of the base material with the silicon nitride being the main component in which α expressed by an expression:α=ä(X-Y)/X}×100 is 20 to 50%, and this tool constitutes its characteristic feature of having this cutting tool and a supporting body to support this cutting tool. However, X and Y in the expression are as follows: X: Feed speed (mm/rev) in chipping of a knife edge in a chipping resistance test of the base material. Y: Feed speed (mm/rev) in chipping of the knife edge in a chipping resistance test of the cutting tool constituted by forming the covering layer on the surface of the base material. However, a condition of the chipping resistance test is as follows: cutting material: FC200, cutting speed: 150m/min, cutting depth: 2.0mm, cutting method: dry type, knife edge treatment: 0.2mm×25 degrees. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cutting tool and a tool. More specifically, the present invention relates to a silicon nitride-based substrate having high adhesion between a substrate and a coating layer formed on the surface thereof and excellent wear resistance. The present invention relates to a cutting tool in which a coating layer is formed on the surface of a material, and a tool having the cutting tool.

  Ceramics useful as wear-resistant materials and impact-resistant materials are widely used in cutting tools due to their characteristics. Among such ceramics, silicon nitride is particularly useful as a cutting tool material because it has high strength and high toughness and a low thermal expansion coefficient.

  However, when a hard material such as tag tile cast iron is cut with the cutting tool made of silicon nitride, there is a problem that the cutting tool is significantly worn. In order to solve this problem, there has been proposed a cutting tool in which a coating layer made of a specific material is formed on a silicon nitride surface (see Patent Documents 1 and 2).

Japanese Patent Publication No. 3-49682 JP-A-6-246511

In Patent Document 1, an intermediate layer made of a coating layer of Al ₂ O ₃ and / or AlON is provided on the surface of a base material mainly composed of Si ₃ N ₄ , and TiC, TiN or TiCN is coated on the intermediate layer. A cutting ceramic tool provided with an outer layer comprising layers is disclosed.

  Further, Patent Document 2 includes yttrium oxide, rare earth oxide, and silicon oxide, and the remainder is formed on the surface of a silicon nitride-based ceramic substrate as a dispersed phase forming component, Ti carbide, nitride, carbonitride. Nitrid formed by forming a hard coating layer composed of one single layer or two or more layers of carbon oxide, nitride oxide, carbonitride oxide, and aluminum oxide with an average layer thickness of 1 to 20 μm A silicon-based ceramic cutting tool is disclosed.

  The coating layers in Patent Documents 1 and 2 are layers intended to improve wear resistance and impact resistance. However, it is difficult to avoid internal strain caused by residual stress due to heat, and when this internal strain is great, there is a disadvantage that the coating layer is peeled off from the base material.

  That is, since the cutting tool is heated at the time of manufacture or use, the cutting tool is particularly changed from a high temperature state to a low temperature state due to a difference in thermal expansion coefficient between the base material and the coating layer or a difference in thermal expansion coefficient between the coating layers. When migrating, a large residual stress may be applied, and internal stress is generated by the stress.

  By the way, in the said patent documents 1 and 2, regarding the adhesiveness of a base material and a coating layer, the chipping resistance of the base material before forming a coating layer, and the cutting tool formed by forming a coating layer on the surface of a base material No mention is made of the fracture resistance of.

  In order to solve the problems in the cutting tools described in Patent Documents 1 and 2, a silicon nitride tool in which a substrate side layer, an intermediate layer, and an outermost layer are formed on the substrate surface has been proposed (see Patent Document 3).

Japanese Patent Laid-Open No. 10-212183

  In Patent Document 3, in a surface-coated silicon nitride tool having a coating layer on the surface of a substrate mainly composed of silicon nitride, the coating is a substrate side layer made of AlON provided on the surface of the substrate; The three layers of the intermediate layer provided on the surface of the substrate side layer and the outermost layer made of TiN provided on the surface of the intermediate layer are provided, and the thickness of the coating layer is 2 to 8 μm, A surface-coated silicon nitride tool is disclosed in which the intermediate layer is composed of one or more intermediate layers selected from AlON, TiC, TiN, and TiCN.

  The surface-coated silicon nitride tool is a tool intended to improve wear resistance while maintaining good adhesion between the substrate and the coating layer. However, the silicon nitride tool has not yet reached a satisfactory level in terms of practical and stable cutting performance under severe cutting conditions.

  Also in Patent Document 3, regarding the adhesion between the substrate and the coating layer, the fracture resistance of the base material before forming the coating layer and the fracture resistance of the cutting tool formed by forming the coating layer on the surface of the base material There is no mention of sex.

  In recent years, under the severely and chemically severe cutting conditions, in the cutting of work materials, the labor saving and efficiency have been increasingly demanded. As described above, This has been dealt with by forming a coating layer on the surface of the substrate and making the coating layer formed thicker.

  However, when the base material is silicon nitride, there is a problem that the adhesion between the silicon nitride as the base material and the coating layer formed on the surface thereof is poor due to the poor chemical affinity. there were. For this reason, in a cutting tool in which a coating layer is formed on the surface of a base material containing silicon nitride as a main component, inconvenience that chipping or peeling of the coating layer at the blade edge portion is likely to occur.

  The present invention solves such a conventional problem, has high adhesion between the base material and the coating layer formed on the surface thereof, and has excellent wear resistance, and is based on silicon nitride as a main component. It is an object of the present invention to provide a cutting tool in which a coating layer is formed on the surface of a material and a tool having the cutting tool.

The first means for solving the problems of the present invention is as follows:
A cutting tool characterized in that a coating layer is formed on the surface of a base material mainly composed of silicon nitride, in which α represented by the following formula is 20 to 50%.
α = [(X−Y) / X] × 100
However, in the said formula, X and Y are as follows.
X: Feed speed (mm / rev) at the time of chipping of the cutting edge in the chipping resistance test of the substrate.
Y: Feed rate (mm / rev) at the time of chipping of the cutting edge in a chipping resistance test of a cutting tool formed by forming a coating layer on the surface of the substrate.
However, the conditions for the fracture resistance test are as follows.
Work material: FC200
Cutting speed: 150 m / min
Cutting depth: 2.0mm
Cutting method: Dry type Cutting edge treatment: 0.2 mm x 25 degrees

Preferred embodiments of the first means of the present invention include the following cutting tools (1) to (4).
(1) A cutting tool in which the base material contains at most 4% by volume of a sintering aid as an allowable amount.
(2) The cutting tool in which the sintering aid is at least one selected from Mg, Al, Y, Ti, Zr, Hf, Sr, rare earth element oxides or nitrides, and solid solutions thereof.
(3) The cutting tool, wherein the coating layer is a single layer or a plurality of layers formed of at least one selected from Al, Ti oxides, nitrides, carbides, borides, and solid solutions thereof.
(4) A cutting tool in which the coating layer is formed by a chemical vapor deposition method.

The second means for solving the problems of the present invention is as follows:
A tool comprising the cutting tool according to the first means and a support for supporting the cutting tool.

  According to the present invention, there is provided a cutting tool having a coating layer formed on the surface of a base material mainly composed of silicon nitride, to which fracture resistance is reduced to some extent. However, the degree of decrease in the fracture resistance does not cause chipping or peeling of the coating layer at the cutting edge, and is practically limited to a range that does not hinder the machinability.

  The cutting tool according to the present invention is a tool that improves the adhesion between the base material and the coating layer formed on the surface thereof after accepting the above-described decrease in fracture resistance to a practical extent. Thus, the cutting tool has excellent wear resistance under severely and chemically severe cutting conditions.

  Moreover, according to this invention, the tool which has the said cutting tool and a support body is provided. Thus, the contribution to the field of tool design and manufacture is enormous.

The cutting tool of the present invention is formed by forming a coating layer on the surface of a base material mainly composed of silicon nitride, in which α expressed by the following formula is 20 to 50%.
α = [(X−Y) / X] × 100

However, in the said formula, X and Y are as follows.
X: Feed speed (mm / rev) at the time of chipping of the cutting edge in the chipping resistance test of the substrate.
Y: Feed rate (mm / rev) at the time of chipping of the cutting edge in a chipping resistance test of a cutting tool formed by forming a coating layer on the surface of the substrate.

However, the conditions for the fracture resistance test are as follows.
Work material: FC200
Cutting speed: 150 m / min
Cutting depth: 2.0mm
Cutting method: Dry type Cutting edge treatment: 0.2 mm x 25 degrees

  The base material constituting the cutting tool of the present invention contains silicon nitride as a main component. The base material may be silicon nitride alone or may contain a sintering aid.

  There is no limitation on the method for producing the base material containing silicon nitride as a main component, and a well-known manufacturing method can be widely adopted. For example, first, a raw material powder containing silicon nitride as a main component and desired The mixture with the sintering aid used is molded to obtain a molded body, and then the molded body is heated in nitrogen gas at 1700 to 1800 ° C. for 0.5 to 5 hours (this heat treatment is performed as “ Furthermore, it may be referred to as “primary sintering treatment”), and further heated in nitrogen gas at 1400 to 1600 ° C. for 0.5 to 3 hours (this heating treatment is referred to as “secondary sintering treatment”). Can be manufactured.

  In producing the substrate, it is desirable to sinter the raw material powder without using a sintering aid. This is because the sintering aid contained in the base material produced using the sintering aid acts as an impurity. However, in order to efficiently sinter raw material powder and produce a high-density substrate, the use of a sintering aid is unavoidable.

Although the sintering aid is not limited, for example, Mg, Al, Y, Ti, Zr, Hf, Sr, rare earth elements (Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, There may be mentioned at least one selected from oxides or nitrides of Dy, Ho, Er, Tm, Yb, and Lu) and their solid solutions. Among these sintering aids, Al ₂ O ₃ , MgO, Y ₂ O ₃ , ZrO ₂ and Yb ₂ O ₃ are preferable.

  The solid solution is in a state where the different elements or compounds are in solid solution with each other. As the sintering aid, the element, the compound or the solid solution may be used alone, or two or more kinds may be used in combination.

  As described above, it is best to sinter the raw material powder without using a sintering aid to produce the base material. When producing the material, the amount of sintering aid contained in the resulting substrate is allowed to be at most 4% by volume.

  The base material mainly composed of silicon nitride thus manufactured is polished into the SNGN120408 shape defined in the ISO standard. The cutting tool of the present invention is a tool formed by forming a coating layer on the surface of a base material mainly composed of silicon nitride thus manufactured.

  The coating layer formed on the surface of the base material is not limited, but for example, a layer formed of at least one selected from Al or Ti oxides, nitrides, carbides or borides, and solid solutions thereof. Can be mentioned.

  The coating layer formed on the surface of the substrate may be a single layer formed of at least one selected from the oxides, nitrides, carbides or borides of Al or Ti and their solid solutions. A plurality of layers formed of different compounds may be used.

  The coating layer formed on the surface of the substrate may be formed by a chemical vapor deposition method (CVD method) or a physical vapor deposition method (PVD method). Since the coating layer having excellent adhesion can be formed by the mutual diffusion and reaction, it is preferable to use the CVD method. As this CVD method, a commonly used method can be adopted, and there are no special restrictions on conditions.

As described above, the cutting tool of the present invention is formed by forming a coating layer on the surface of a base material mainly composed of silicon nitride, and α expressed by the following formula is 20 to 50%. .
α = [(X−Y) / X] × 100

However, in the said formula, X and Y are as follows.
X: Feed speed (mm / rev) at the time of chipping of the cutting edge in the chipping resistance test of the substrate.
Y: Feed rate (mm / rev) at the time of chipping of the cutting edge in a chipping resistance test of a cutting tool formed by forming a coating layer on the surface of the substrate.

However, the conditions for the fracture resistance test are as follows.
Work material: FC200
Cutting speed: 150 m / min
Cutting depth: 2.0mm
Cutting method: Dry type Cutting edge treatment: 0.2 mm x 25 degrees

  Under the condition of the fracture resistance test, α represented by the above formula is 20 to 50%, which means that the cutting tool has a certain degree of fracture resistance reduction. However, the degree of the decrease in the fracture resistance does not cause chipping or peeling of the coating layer at the blade edge portion, and is practically limited to a range that does not hinder the machinability.

  A cutting tool in which a coating layer is formed on the surface of a base material containing silicon nitride as a main component can exhibit excellent machinability even under severely and thermally severe cutting conditions. In order to be able to do so, how to strengthen the adhesion between the base material and the coating layer is an extremely important factor.

  However, as a result of various studies on the above points, the stronger the adhesion, the more the coating layer is formed on the surface of the base material against the fracture resistance of the base material before forming the coating layer. It has been found that the fracture resistance of the substrate of the cutting tool is significantly reduced.

  When the coating layer is formed on the surface of the base material, since the difference in thermal expansion between the base material and the coating layer is extremely large, residual stress is generated inside the cutting tool. It is caused by stress.

  On the other hand, if the adhesion between the substrate and the coating layer is poor, the coating layer easily peels off, so that the decrease in fracture resistance is reduced, but the coating layer is formed on the surface of the substrate, The object of obtaining a cutting tool with excellent wear resistance cannot be achieved.

  The cutting tool according to the present invention is based on the above-mentioned anti-twisting event, and accepts a slight decrease in fracture resistance that can be tolerated. The intended tool could be a cutting tool having excellent wear resistance and impact resistance under severely and chemically severe cutting conditions.

  Α represented by the above formula needs to be 20 to 50%. If it is less than 20%, the adhesion between the substrate and the coating layer is poor, and if it exceeds 50%, it cannot be used practically.

Moreover, the tool of this invention has the said cutting tool and the support body which supports this cutting tool.
An example of the tool of the present invention is shown in FIG. The tool 1 is formed by attaching a cutting tool 4 having a coating layer 3 formed on the surface of a substrate 2 to a support 5. In FIG. 1, the tool 1 is shown in a state in which a part of the coating layer 3 in the cutting tool 4 is partially peeled to expose the base material 2. 6 is a flank. The substrate 2 and the coating layer 3 are as described above.

As long as the tool of this invention has the cutting tool 4 and the support body 5, it is not restrained by the shape shown by FIG.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples.
(Examples 1-7 and Comparative Examples 1-8)

Α-type silicon nitride (oxygen amount 1.0%) powder having an average particle size of 0.5 μm, Al ₂ O ₃ , MgO, Y ₂ O ₃ , ZrO ₂ or Yb ₂ O ₃ powder having an average particle size of 1 μm, respectively, 1 was weighed and collected so as to have the composition shown in FIG. 1, and wet mixed and pulverized for 24 hours using a ball mill using ethyl alcohol as a solvent. Thereafter, 2% by mass of paraffin was added and press-molded at a pressure of ¹ ton / cm ² (9806.65 × 10 ⁻¹ Pa) to obtain a molded body.

After degreasing the molded body, the firing conditions shown in Table 2 under a nitrogen gas atmosphere [however, for the molded body 1, nitrogen at 1600 ° C. for 2 hours and 1000 atm (1013.25 × 10 ⁵ Pa) Hot isostatic pressing (HIP) was performed in gas. ] To obtain a dense sintered body having the theoretical density ratio shown in Table 2. This sintered body was polished into the ISO standard SNGN120408 shape to obtain a base material.

The base material was set in a chemical vapor deposition apparatus (CVD apparatus), and a coating layer (TiCN layer, TiN layer, Al ₂ O ₃ layer) was formed on the surface of the base material according to the following conditions. The cutting tool shown in FIG.

[TiCN layer]
Temperature: 900 ° C
Pressure: 75hPa
H ₂ : 18 L / min
N ₂ : 9.5 L / min
TiCl ₄ : 1.5 ml / min
CH ₃ CN: 0.28 ml / min

[TiN layer]
Temperature: 900 ° C
Pressure: 600 hPa
H ₂ : 13 L / min
N ₂ : 10.5L / min
TiCl ₄ : 1.1 ml / min

[Al ₂ O ₃ layer]
Temperature: 1000 ° C
Pressure: 80hPa
H ₂ : 17 L / min
CO ₂ : 0.5 L / min
HCl: 0.9 L / min
AlCl ₃ : 1.2 ml / min
H ₂ S: 60 mL / min

  However, about Comparative Examples 6-8, the coating layer (TiCN layer, TiN layer) was formed by the physical vapor deposition method (PVD method) on the following conditions.

[TiCN layer]
Temperature: 550 ° C
Pressure: 2.7Pa
N ₂ : 1000 ml / min
CH ₄ : 1000 ml / min
Arc current: 150A
Bias voltage: 300V

[TiN layer]
Temperature: 500 ° C
Pressure: 4.0Pa
N ₂ : 1000 ml / min
Arc current: 150A
Bias voltage: 150V

  The tool shown in FIG. 1 was produced using the cutting tool manufactured in this way. Separately, a tool having a cutting tool made of a base material on which the coating layer was not formed was produced. Using these two types of tools, a chipping resistance test of the cutting tools was performed. The conditions for this fracture resistance test are as follows.

Work material: FC200
Cutting speed: 150 m / min
Cutting depth: 2.0mm
Feeding speed: 0.7-1.3mm / rev
Cutting method: Dry type Cutting edge treatment: 0.2 mm x 25 degrees

Table 4 shows α represented by the following formula.
α = [(X−Y) / X] × 100

However, in the said formula, X and Y are as follows.
X: Feed rate (mm / rev) at the time of chipping of the cutting edge in the chipping resistance test of the base material (base material on which the coating layer is not formed).
Y: Feed speed (mm / rev) at the time of chipping of the cutting edge in the chipping resistance test of the cutting tool 4.

  Moreover, the wear resistance test of the cutting tool was implemented using the two types of tools. The conditions for this abrasion resistance test are as follows.

Work material: FC200
Cutting speed: 100 m / min
Cutting depth: 1.0mm
Feeding speed: 0.1mm / rev
Cutting method: Dry Cutting edge treatment: 0.2 mm x 25 degrees Cutting time: 60 min

  Table 4 shows the wear amount of the flank.

  From the results shown in Table 4, the cutting tool having α of 20 to 50% is a cutting tool having high adhesion between the base material and the coating layer formed on the surface thereof and having excellent wear resistance. I understand.

FIG. 1 is a plan view showing an example of the tool of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tool 2 Base material 3 Covering layer 4 Cutting tool 5 Support body 6 Flank

Claims (6)

The cutting tool characterized by forming a coating layer on the surface of the base material which has silicon nitride as a main component and (alpha) represented by a following formula is 20 to 50%.
α = [(X−Y) / X] × 100
However, in the said formula, X and Y are as follows.
X: Feed speed (mm / rev) at the time of chipping of the cutting edge in the chipping resistance test of the substrate.
Y: Feed rate (mm / rev) at the time of chipping of the cutting edge in a chipping resistance test of a cutting tool formed by forming a coating layer on the surface of the substrate.
However, the conditions for the fracture resistance test are as follows.
Work material: FC200
Cutting speed: 150 m / min
Cutting depth: 2.0mm
Cutting method: Dry type Cutting edge treatment: 0.2 mm x 25 degrees   The cutting tool according to claim 1, wherein the base material contains an allowable amount of at most 4% by volume of a sintering aid.   The cutting tool according to claim 2, wherein the sintering aid is at least one selected from Mg, Al, Y, Ti, Zr, Hf, Sr, rare earth element oxides or nitrides, and solid solutions thereof. .   4. The coating layer according to claim 1, wherein the coating layer is a single layer or a plurality of layers formed of at least one selected from oxides, nitrides, carbides and borides of Al or Ti, and solid solutions thereof. The cutting tool according to Item.   The cutting tool according to any one of claims 1 to 4, wherein the coating layer is formed by a chemical vapor deposition method. A tool comprising the cutting tool according to any one of claims 1 to 5 and a support for supporting the cutting tool.

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