JPH04300104A - Surface-coated cutting tool - Google Patents

Abstract

PURPOSE:To prolong the service life of a tool by providing at least one hard layer, of which residual tensile and compressive stresses shows specified values in a tool, of which substrate is made of WC-group cemented carbide, etc., and on which a hard layer is coated. CONSTITUTION:Either one of a WC-group cemented carbide, a Ti(CN)-group cermet, a Si3N4-group ceramic, and a Al2O3-group ceramic is used as a substrate, and a specified hard layer is coated on the surface of the substrate to obtain a desired cutting tool. The hard layer is composed of two kinds of multiple layers of more than one or more layers of compounds of one or more of metal elements selected from 4a, 5a, and 6a group metals and Al and Si groups in a periodic table and one or more of non-metal elements selected from a group consisting of carbon, nitrogen, oxide, and boron. Then the hard layer is adjusted so that residual tensile and compressive stresses in the coating layer are below 9kg/mm<2> by a treatment such as sand blasting, etc.

Description

[Detailed description of the invention]

[Industrial Application Field] This invention relates to WC-based cemented carbide, T
The present invention relates to a cutting tool having a substrate made of any one of i(CN)-based cermet, Si3 N4-based ceramics, and Al2 O3-based ceramics, and whose surface is coated with a hard layer. This invention relates to a surface-coated cutting tool that has high adhesion to a substrate and has excellent wear resistance.

0002

[Prior Art] Cutting tools that have a WC-based cemented carbide as a base and have a hard layer coated on the surface by chemical vapor deposition have been widely used.Generally, the hard layer coated by chemical vapor deposition is
It is also known that tensile residual stress due to thermal stress acts after coating due to the relationship of the coefficient of thermal expansion with the substrate, and that this reduces chipping resistance.

For example, “Journal of the Japan Institute of Metals Vol. 50
No. 3 (1986) 320-327, a study was reported on the residual stress of TiN coated on WC-based cemented carbide by chemical vapor deposition (hereinafter referred to as CVD).
According to this document, tensile residual stress acts on the TiN layer formed by the CVD method. The hard layer under such tensile residual stress is prone to cracking.
Because of the poor fracture resistance, Japanese Patent Application Laid-Open No. 64-31972 proposes applying an impact force of 50 kg/m to the coating layer by applying as strong an impact force as possible to the surface of the coated sintered alloy using the CVD method.
A coated sintered alloy with improved strength and fracture resistance by applying a compressive stress of m2 or more is disclosed.

0004

[Problem to be solved by the invention] However, the above conventional C
Cutting tools made with coated sintered alloys that have high tensile residual stress using the VD method, or coated sintered alloys that have been coated with high compressive residual stress by applying a strong impact force from the surface after coating, are designed to have cutting stress on the cutting edge. When used for concentrated micro-cutting, finishing cutting, etc., abnormal wear is likely to occur due to shedding of crystal particles constituting the coating layer, and the life of this cutting tool is short.

[0005]

[Means for Solving the Problems] The present inventors have conducted various studies to solve the problems, and have found that although compressive residual stress in the coating layer does lead to improved fracture resistance,
High compressive residual stress and high tensile residual stress cause abnormal wear due to shedding of crystal grains that make up the coating layer.
Furthermore, the adhesion between the coating layer and the coating layer or between the coating layer and the substrate is reduced, and if a hard layer is coated with almost no residual stress, the crystal grains of the coating layer will be less likely to fall off, and the They found that adhesive strength could be obtained.

[0006] The present invention was made based on this knowledge, and includes WC-based cemented carbide, Ti(CN)-based cermet, Si3 N4-based ceramics, and Al2-based cemented carbide.
The base is made of any one of O3-based ceramics, and the surface is coated with metals from groups 4a, 5a and 6a of the periodic table, Al,
One or more metal elements selected from the group of Si,
1 selected from the group consisting of carbon, nitrogen, oxygen and boron
In a cutting tool coated with a hard layer composed of one kind of single layer or two or more kinds of multilayers of a species or a compound of two or more nonmetallic elements, the tensile residual stress or compressive residual stress of the coating layer is The present invention is characterized by a surface-coated cutting tool coated with at least one hard layer having a hardness of 9 kgf/mm2 or less. Furthermore, in the surface-coated cutting tool of the present invention, it is more preferable that all the coating layers have a tensile residual stress or a compressive residual stress of 9 kgf/mm 2 or less.

[0007] As a method of reducing the tensile residual stress or compressive residual stress of the hard layer by the CVD method of the present invention to 9 kgf/mm2 or less, a mechanical treatment method or a surface treatment method in which sandblasting or shot peening is applied to the surface after the hard layer is coated. There are physical treatment methods such as ion irradiation.

[0008]

[Example] Example 1 A commercially available WC-based cemented carbide cutting tool (shape: SNMG120408) equivalent to ISO standard M20 was used as a base, and a single layer or two types shown in Table 1 were coated on the surface of this base using a normal CVD method. After coating the above multiple hard layers, the single layer or two layers described above are applied.
Approximately 5.0 kg/cm2 of alumina balls with an average particle size of 0.2 mm are placed on the surface of each layer of the multi-layered hard layer.
The surface-coated cutting tools 1-5 of the present invention and the comparative surface-coated cutting tools 1-5 (however, the surface-coated cutting tools 1-5 of the present invention and the comparative surface-coated cutting tools 1-5 were Coated cutting tools 1 and 2 were manufactured without shot peening. The residual stress was measured by X-ray diffraction using the 2θ-Sin2Ψ method, and the measured residual stress of each layer is shown in Tables 1 to 4.

Using these surface-coated cutting tools 1 to 5 of the present invention and comparative surface-coated cutting tools 1 to 5, cutting tests were conducted under the following conditions, and the results are shown in Table 5. (Cutting test 1) Work material: SCM440 (HB 250), cutting speed: 2
00m/min, Feed: 0.05mm/rev, Depth of Cut: 0.3mm, dry, micro-cutting was performed, and the time until the flank wear width reached 0.4mm was measured. (Cutting test 2) Work material: FC3
0 (HB 160), Cutting speed: 250 m/min, Feed: 0.1 mm/rev, Depth of cut: 0.5 mm, dry, finish cutting and measure the time until the flank wear width reaches 0.4 mm. .

0010

[Table 1] ☆: Beyond the scope of the present invention.

[0011]

[Table 2] ☆: Beyond the scope of the present invention.

0012

[Table 3]

[0013]

[Table 4]

[0014]

[Table 5]

Example 2 Commercially available tool shapes: TiCN-based cermet of TNGN160412, Si3 N4-based ceramics, and Al2
Using various tool materials made of O3-based ceramics as a base, the surface of this base is coated with multiple hard layers shown in Tables 6 to 7 by a normal CVD method, and then the respective surfaces of each layer of the multiple hard layers are coated. The surface-coated cutting tool 6 of the present invention was prepared by subjecting the surface-coated cutting tool 6 of the present invention to alumina balls having an average particle diameter of 0.2 mm and bombarding the surface with compressed air of approximately 5.0 kg/cm2 for a predetermined period of time to impart residual stresses shown in Table 6. - 8 and comparative surface-coated cutting tools 6-8 (however, comparative surface-coated cutting tools 1-2 were not subjected to shot peening). The residual stress was measured by X-ray diffraction using the 2θ-Sin2Ψ method in the same manner as in Example 1, and the measured residual stress of each layer is shown in Tables 6 and 7.

Using these surface-coated cutting tools 6 to 8 of the present invention and comparative surface-coated cutting tools 6 to 8, cutting tests were conducted under the following conditions, and the results are shown in Table 8. (Cutting test 3) Work material: SNCM439 (HB 310) Cutting speed: 230 m/min Feed: 0.05 mm/rev Depth of cut: 0.3 mm Dry micro-cutting was performed. Measure the time until the flank wear width reaches 0.2mm.

[0017]

[Table 6] ☆: Beyond the scope of the present invention.

[0018]

[Table 7]

[0019]

[Table 8]

[0020]

Effects of the Invention As is clear from the results of Examples 1 and 2 above, WC-based cemented carbide, Ti(CN)-based cermet, Si3 N4-based ceramics, and Al2 O3
Any one of the base ceramics is used as a base, and on the surface thereof, one or more metal elements selected from the group of group 4a, 5a and 6a metals of the periodic table, Al, and Si, carbon,
A single layer or two of a compound of one or more nonmetallic elements selected from the group consisting of nitrogen, oxygen, and boron.
In a cutting tool coated with a hard layer composed of multiple layers of different types, the surface-coated cutting tool is coated with at least one hard layer whose tensile residual stress or compressive residual stress of the coating layer is 9 kgf/mm2 or less. It can be seen that the tool has excellent flank wear resistance in continuous cutting, especially in micro-continuous cutting.

Claims (2)

[Claims] [Claim 1] WC-based cemented carbide, Ti(CN)-based cermet, Si3 N4-based ceramics, and Al2
The base is made of any one of O3-based ceramics, and the surface is coated with metals from groups 4a, 5a and 6a of the periodic table, Al,
one or more metal elements selected from the group of Si;
1 selected from the group consisting of carbon, nitrogen, oxygen and boron
In a cutting tool coated with a hard layer composed of one type of single layer or two or more types of multilayers of a species or a compound of two or more nonmetallic elements, the tensile residual stress or compressive residual stress of the coating layer is A surface-coated cutting tool characterized by being coated with at least one hard layer having a hardness of 9 kgf/mm2 or less. 2. The surface-coated cutting tool according to claim 1, wherein the tensile residual stress or compressive residual stress of all the coating layers is 9 kgf/mm 2 or less. 0001