JPS62228305A - Alumina coated tool and manufacture method therefor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a coated tool with excellent toughness, and more particularly to a coated tool in which the outermost layer of the coating layer is formed of alumina, and a method for manufacturing the same.

(Prior art) Cutting tools have traditionally been manufactured from tool steel, high-speed steel, die steel, cemented carbide, etc., but recently, in order to further improve cutting characteristics, cutting tools have been manufactured using the above-mentioned materials as base materials. ,
A coating layer having excellent wear resistance is formed on the outer surface by a vapor phase growth method such as a CVD method.

As such a coating layer, titanium-based materials such as titanium carbide and titanium carbonitride, and alumina-based materials are mainly used, but in terms of strength and toughness as coated tools,
Because titanium-based materials are superior, titanium-based materials are often used for tough coating tools.

However, since alumina-based materials have excellent chemical stability and heat resistance, they are useful coating materials when used in high-speed cutting areas, so it is possible to improve the strength and toughness of alumina-based coated tools. This is considered to be one issue.

Therefore, FIG. 1 shows a microscopic photograph of the surface structure of a conventional alumina film.

Normally, when an alumina film is formed by a vapor phase growth method such as the CVD method, the alumina film is formed as an aggregate of fine crystals with a grain size of several microns, as is clear from Figure 1. The unevenness is formed according to the

In addition, aggregates of tens of microns may sometimes be formed due to abnormal growth of crystal grains.

When such uneven portions are cut, stress is locally applied to the film itself due to friction with chips of the work material, which causes a decrease in toughness. In addition, if the workpiece material is soft, chips may be welded to the uneven portions, causing a reduction in the performance of the tool.

(Structure of the Invention) The present inventors have conducted research to solve the above problem, and have found that by polishing the surface of an alumina film formed by a vapor phase growth method while leaving a certain thickness, the surface can be smoothed. It has been found that while maintaining the wear resistance of the film itself, it can increase strength and toughness and prevent damage to the cutting edge during cutting.

That is, according to the present invention, in a coating tool in which an alumina film is formed on the outer surface of the base including at least the blade portion, the alumina film has a thickness of 0.5 to 5 μm or more, and the surface roughness of the film is Provided is an alumina coated tool characterized by a thickness of 1 μm or less.

Further, according to the present invention, after forming an alumina film on the outer surface of the substrate by a vapor phase growth method, the surface of the alumina film including at least the blade part has a surface roughness of 1 μm or less and a thickness of 0.5 μm.
Provided is a method for manufacturing an alumina coated tool, which is characterized by mechanical polishing to a thickness of 5 μm or more.

The present invention will be explained in detail below.

According to the present invention, it is important to control the surface roughness of the alumina film surface to 1 μm or less, particularly 0.5 μm or less.

The surface roughness here refers to the maximum height roughness according to JISBO601.
). This configuration reduces the resistance between the chips of the workpiece and the blade surface, prevents the generation of local external stress, reduces film defects, and improves tool life. I can do it.

The surface of the alumina film when it is formed is smoother as the film thickness decreases, depending on the film formation conditions, but in order to obtain the desired cutting performance, it is necessary to increase the film strength. The thickness should be controlled between 0.5 and 5 μm, especially between 1 and 3 μm. If the film thickness is less than 0.5 μm, the wear resistance of alumina will not be sufficiently exhibited. On the other hand, if the thickness exceeds 5 μm, the film strength will be insufficient and defects will easily occur.

The substrate used in the present invention itself requires a certain degree of mechanical strength, such as WC.

Examples include carbides such as TiC, T1CN, and TiN, cemented carbides or cermets mainly composed of carbonitrides, and sintered bodies such as zirconia and 5iJ4+StC. In particular, cemented carbide is desirable from the viewpoint of cutting performance for alumina film.

In particular, it is desirable to coat a carbide or carbonitride such as Tic or T1CN on a cemented carbide base, and then coat alumina thereon.

According to the method of manufacturing an alumina coated tool of the present invention, first, a known vapor phase growth method such as thermal CVD, RF plasma CVD, microwave C
VD, ECR Braz? CVD, etc. (7) After forming an alumina film by a PVD method such as a CVD method, an ion beam method, or a suvafuta method, the alumina film is polished by known mechanical polishing, such as barrel polishing or honing treatment,
The surface roughness is set to 1 μm or less, particularly 0.5 μm or less. FIG. 2 is a micrograph of the surface structure of the alumina film after polishing according to the present invention. In this polishing process, the crystal grain size of the alumina film provided on the substrate is important.

As is clear from Example 2 described later, the defect rate depends on the crystal grain size. Therefore, according to the present invention, the toughness of the film is improved by the polishing treatment in any case, but in particular, the toughness is improved by 0.1 to 3.
．． At a particle size of 0 μm, the effect is significant.

Also, the alumina film after polishing is set to have a thickness of 0.5 to 5 μm, particularly 1 to 3 μm, for the reasons mentioned above.

Furthermore, the polishing treatment is sufficient to eliminate the valleys formed between the individual crystal grains of the formed alumina film, and further polishing will only reduce the alumina film thickness and improve the wear resistance. undesirable as it tends to deteriorate the

The invention is illustrated by the following example.

Example A cemented carbide substrate was placed in a reaction vessel, and the substrate was heated to 1000°C, and 11□, C) 12 and T
Introducing and introducing a mixed gas of iC1a at a ratio of 87:5:8,
TiCrrJ with a thickness of about 6 μm was formed on the surface of the substrate.

Next, H2, GO□ and AlCl3 gases were introduced into the same container at a volume ratio of 45:45:10, and the substrate was heated to 1000°C, with an average film thickness of 3 μm and a crystal grain size of 2.3 μm.
of Alz(hN) was formed.

Note that the maximum surface roughness of this film surface was 1.3 μm.

The obtained sample was subjected to a honing treatment on the AlzO film surface at the cutting edge portion using a commercially available beater alterter, and a plurality of samples with different surface roughness of the polished surface were manufactured.

Flank wear amount was measured for each sample under the following cutting conditions.

Chip shape TNMG332 (blade honing N
0.06mm) Work material SCM435 Cutting speed V・200m/min Feed f=0.3mm/rev Depth of cut
d=2mm In addition, the fracture rate was determined as a toughness test under the following cutting conditions. The breakage rate was expressed as the percentage of cutting edges that were broken within 15 seconds.

Chip shape TNMG332 Work material 545C 4 grooves (groove width 5mm) Cutting speed V=100m/muin Depth of cut d
=2mm feed f=0.3mm/rev cutting time
15 (sec) The results are shown in 11hl-5 of Table 1. Furthermore A1zO
A similar cutting test was conducted on a sample prepared by providing an i-film of 7.0 μm and undergoing polishing treatment. The results are shown in Table 1 N116. In addition, the deposition conditions of the AlzOz film were changed, and the crystal grain size was 3.
．． A 5 μm film was provided, polished, and tested in the same manner.

The results are shown in Table 1.

As is clear from Table 1, sample No. 1 with a surface roughness of more than 1 μm has less flank wear but has a large chipping rate and low toughness.

On the other hand, samples 2 to 4 of the present invention, each having a surface roughness of 1 μm or less, were able to keep the defect rate to 40% or less, and it was confirmed that the toughness of the film was improved. Note that the film thickness decreases depending on the honing treatment time.
It can be seen that since the amount of flank wear tends to increase, the amount of polishing by the honing process should be minimized.

Therefore, if the film thickness is less than 0.5 μm (grade 5), the amount of wear increases and the alumina coating becomes ineffective.On the other hand, if the film thickness exceeds 5 μm (inhibition 6), the defect rate increases and the crystallization Even when the particle size exceeds 3 μm (Arashi 7), the defect rate increases.

Example 2 Next, in Example 1, the conditions for forming the alumina film were changed so that the film thickness was 3 μm and the alumina crystal grain size was 0.1 μm.
less than m, 0.1 to 1.0 μrn, 1.0 to 2.0 μm
, 2.0-3.0 μm, 3.0-7.0
Five types of samples were prepared. The obtained sample was honed for 5 seconds.

These samples were tested under the following cutting conditions, and the defect rate was determined in the same manner as in Example 1.

Chip shape TNMG332 (blade honing'!
0.06mm) Work material SCM435 (4
Cutting speed V=120m/min Depth of cut d=2mm Feed f=0.3mm/rev Cutting time
The 15 second results are shown in Table 2.

Table 2 From Table 2, it was found that alumina crystal grains having a diameter of 0.1 μm or more, particularly o, l to 2.0 μm, are excellent in terms of toughness as a tool.

(Effects of the Invention) As described above in detail, according to the alumina coating tool of the present invention, the irregularities on the surface of the alumina film formed by the vapor growth method are polished by mechanical polishing, thereby removing the film caused by the irregularities. It becomes possible to provide a strong alumina-coated tool that can prevent peeling, strength deterioration, and welding, and has a long life and excellent wear resistance.

[Brief explanation of drawings]

Figure 1 shows a diagram of the surface structure of a conventional alumina film W1. mirror photo,
FIG. 2 is a micrograph of the surface structure of the alumina film after polishing according to the present invention.

Claims (4)

[Claims] (1) In a coating tool in which an alumina film is formed on the outer surface of the base including at least the blade part, the alumina film has a thickness of 0.5 to 5 μm, and the surface roughness of the film is 1 μm or less. An alumina coated tool characterized by: (2) The crystal grain size of the alumina film is 0.1 to 3.0μ
The alumina coated tool according to claim 1, which is m. (3) After forming an alumina film on the outer surface of the substrate by a vapor growth method, the surface of the alumina film, including at least the blade part, is mechanically polished to a surface roughness of 1 μm or less and a thickness of 0.5 to 5 μm. A method for manufacturing an alumina coated tool characterized by: (4) The crystal grain size of the alumina film is 0.1 to 3.0μ
The method for manufacturing an alumina-coated tool according to claim 3, wherein the alumina-coated tool is m.