JP2697110B2 - Surface-coated tungsten carbide based cemented carbide cutting tool members - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hard coating layer which has extremely high adhesion to a substrate surface and is used not only for continuous cutting but also for intermittent cutting. The present invention relates to a surface-coated tungsten carbide-based cemented carbide cutting tool member (hereinafter, abbreviated as a coated cemented carbide cutting tool) which exhibits excellent performance for a remarkably long period of time because peeling is suppressed. .

[Conventional technology]

Conventionally, carbides, nitrides, and carbonitrides (hereinafter, referred to as Ti, respectively) of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide substrate are formed on a surface of a cemented carbide substrate by a chemical vapor deposition method (CVD method) or a physical vapor deposition method (PVD method). Average thickness of one single layer or two or more layers of TiC, TiN, and TiCN) and, if necessary, an uppermost layer of aluminum oxide (hereinafter, referred to as Al ₂ O ₃ ): A coated carbide cutting tool having a hard coating layer of 1 to 10 μm is used for continuous cutting or interrupted cutting of steel or the like.

[Problems to be solved by the invention]

On the other hand, in recent years, there has been a strong demand for labor saving and shortening of the cutting process, and there has been a tendency for cutting under severe conditions to accompany this. Particularly, in the case of intermittent cutting, a hard coating layer of a coated carbide cutting tool is required. At present, peeling is apt to occur, and only a relatively short service life is exhibited.

[Means for solving the problem]

Therefore, the present inventors focused on the above-mentioned conventional coated carbide cutting tool from the above-described viewpoint, and firstly, in order to suppress the peeling of the hard coating layer from the substrate surface, first, the conventional coated carbide cutting tool was used. When the cause of peeling of the hard coating layer of the tool was sought, one of the reasons was that the thermal expansion coefficient of the hard coating layer was significantly different from that of the substrate.
The thermal expansion coefficient of N is 9.8 × 10 ^-6 / ° C, and the TiCN is 9.4 × 10
^-6 / ° C, whereas that of the WC-based cemented carbide substrate is about 5 × 10 ^-6 / ° C. In most cases, Co is diffused into the hard coating layer together with the W component dissolved therein, and pores are formed on the surface of the substrate after the Co migration. The conclusion that the formation of also causes a decrease in the adhesion of the hard coating layer,
As a result of conducting research to solve these problems, as a base layer between the hard coating layer and the substrate, a nitride layer and a carbonitride layer of Zr (hereinafter, referred to as ZrN and ZrCN, respectively) were used. When a single layer of one kind is interposed in a state of a relatively thin layer thickness with respect to the hard coating layer, the underlayer has a thermal expansion coefficient of ZrN constituting 7.6 × 10 ⁻⁶ / ° C.,
And the ZrCN has an intermediate coefficient of thermal expansion between the hard coating layer and the substrate such that the ZrCN is 7.6 × 10 ^-6 / ° C. Therefore, the thermal strain generated between the hard coating layer and the substrate due to high heat generated during cutting Not only is reduced, but also because the underlayer has the property of preventing the diffusion and transfer of Co in the substrate, pores are formed on the surface of the substrate by the diffusion and transfer of Co. Is prevented, and in combination with the fact that the underlayer itself has excellent adhesion to the substrate and the hard coating layer, not only high-speed cutting, heavy cutting such as high feed and high cutting, but also severe Under such conditions, the occurrence of peeling of the hard coating layer can be prevented even under intermittent cutting, and it has been found that excellent wear resistance is remarkably exhibited for a long period of time.

The present invention has been made based on the above findings, and has an average layer thickness of one kind of one of ZrN and ZrCN: 0.05 to 1 μm on the surface of a WC-based cemented carbide substrate. A single layer or two of TiN and TiCN
The present invention is characterized by a coated carbide cutting tool having a hard coating layer having an average layer thickness of 1 to 10 μm, comprising a plurality of kinds of layers and, if necessary, an uppermost layer of Al ₂ O ₃ .

In the coated carbide cutting tool of the present invention, the average layer thickness of the underlayer is set to 0.05 to 1 μm because the layer thickness is 0.1 μm.
If the thickness is less than 05 μm, the desired thermal strain relaxation effect and Co diffusion transfer inhibition effect cannot be obtained. On the other hand, the layer thickness of up to 1 μm is sufficient, and if the thickness is larger than this, the underlayer itself is relatively soft. This is because the wear resistance of the cutting tool member itself is reduced, and the average layer thickness of the hard coating layer is set to 1 to 10 μm when the layer thickness is less than 1 μm. This is because the abrasion resistance cannot be ensured. On the other hand, when the thickness exceeds 10 μm, the hard coating layer itself is chipped or chipped.

〔Example〕

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

As raw material powders, WC powders, all kinds of metal carbide powders, composite metal carbide solid solution powders, and Co powders, each having an average particle size in the range of 0.5 to 10 μm, are prepared. WC-6% (T
i, W) C-4% TaC-8% Co (for base A), WC-8% (T
i, W) C-5% NbC-10% Co (for substrate B) and WC-5.
9% (Ti, W) C-4% (Ta, Nb) C-6% Co (for base C)
And wet-mixed in a ball mill for 72 hours.
After drying, it is pressed into a green compact at a pressure of 1.5 ton / cm ² , and the green compact is heated to 1350 to 1500 ° C. in a vacuum of 1 × 10 ⁻³ torr.
Sintered under the condition of holding for 90 minutes at a predetermined temperature within the range described above, to obtain a sintered body having substantially the same component composition as the compounded composition, and subjecting this sintered body to cutting processing, the shape is JIS · Substrate A as a throw-away chip equivalent to SNG432 C, respectively, and then the WC-based cemented carbide substrate A ~
By forming a base layer and a hard coating layer shown in Table 1 on each surface of C by a normal chemical vapor deposition method, the coated carbide cutting tool of the present invention (hereinafter referred to as the present tool).
1 to 3 were manufactured respectively.

For the purpose of comparison, conventional coated carbide cutting tools (hereinafter, referred to as conventional tools) 1 to 3 were manufactured under the same conditions except that the underlayer was not formed.

This resulting various tools to calculate the adhesion strength by measuring the critical peeling load by the scratch tester, work material: SNCM439 (Hardness: H _B 260) round bar, Cutting speed: 200 meters / min ., feed Ri: 0.3 mm / rev, cut:. 1.5 mm, cutting time: 15 minutes, dry continuous high-speed cutting test of steel in the conditions, as well as work material: SNCM439 (hardness: H _B 310) of Round bar with groove, cutting speed: 140m / min., Feed: 0.25mm / rev., Depth of cut: 2mm, dry intermittent cutting test of steel is performed.In the former test, the flank wear width of the cutting edge and The rake face wear depth was measured, and in the latter test, the cutting time until the occurrence of chipping on the cutting edge was measured. Table 1 shows the average value of the number of 10 test cutting edges.

〔The invention's effect〕

From the results shown in Table 1, the tools 1 to 3 of the present invention have an intermediate coefficient of thermal expansion between that of the substrate and the hard coating layer, and that of the base layer which prevents diffusion and transfer of Co in the substrate to the hard coating layer. Due to the formation, the hard coating layer is bonded to the substrate surface with strong adhesion strength, and the occurrence of peeling of the hard coating layer during cutting is significantly suppressed, so that not only high-speed cutting but also severe conditions While it shows excellent wear resistance even under intermittent cutting underneath and exhibits excellent cutting performance over a remarkably long period of time, the conventional tools 1 to 3 without the formation of the underlayer, the Co In addition to diffusion transfer into the hard coating layer,
It is clear that the hard coating layer easily peels due to a sudden change between the substrate and the hard coating layer, and it is evident that chipping easily occurs particularly in interrupted cutting.

As described above, the coated cemented carbide cutting tool of the present invention has extremely high adhesion of the hard coating layer to the substrate surface, and not only continuous cutting, but also peeling of the hard coating layer particularly when used for intermittent cutting. Since it is significantly suppressed, it has industrially useful characteristics such as exhibiting excellent cutting performance for an extremely long period.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Sonichi Takahashi 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Metals Central Research Laboratory (72) Inventor Yoshikazu Okada 1-27-20 Nishishinagawa, Shinagawa-ku, Tokyo Mitsubishi (56) References JP-A-56-112462 (JP, A) JP-A-55-128574 (JP, A) JP-A-62-213903 (JP, A)

Claims (2)

(57) [Claims] The present invention relates to a method of manufacturing a titanium carbide-based cemented carbide substrate, comprising the steps of: forming a single layer of at least one of nitride and carbonitride of Zr on an underlayer having an average thickness of 0.05 to 1 μm; Cutting tool made of a surface-coated tungsten carbide-based cemented carbide formed by forming a hard coating layer having an average thickness of 1 to 10 μm, consisting of a single layer of nitride or carbonitride or a multilayer of two or more layers. Element. 2. The method according to claim 1, wherein the surface of the tungsten carbide-based cemented carbide substrate is provided with an underlayer having an average layer thickness of 0.05 to 1 μm consisting of a single layer of one of nitride and carbonitride of Zr. Surface-coated tungsten carbide formed by forming a single layer of one or more of nitrides and carbonitrides and a multilayer of aluminum oxide and an uppermost layer of aluminum oxide: a hard coating layer having a thickness of 1 to 10 μm Cutting tools made of base cemented carbide.