JPH02269509A - Surface-covered tungsten carbide group cemented carbide cutting tool - Google Patents

Abstract

PURPOSE:To prevent peeling of a hard covering layer by laminating single layer or multiple layers made of Ti carbide of the like on the surface of a tungsten carbide group cemented carbide basic material through a single layer of Zr carbide or the like to form a cutting tool member. CONSTITUTION:A substrate layer which consists of a single layer made on one kind among Zr carbide, Zr nitride and Zr carbonitride is formed at an average layer thickness of 0.05-1mum on the surface of a tungsten carbide group cemented carbide basic material. Next, a hard covering layer which consists of a single layer made of one kind among Ti carbide, Ti nitride and Ti carbonitride or multiple layers made of more than two kinds of them is formed at an average layer thickness of 1-10mum on the substrate layer to obtain a cutting tool member made of surface-covered tungsten carbide group cemented carbide. A top layer made of aluminium oxide can be also provided on the covering layer made of Ti carbide or the like.

Description

Detailed Description of the Invention [Industrial Application Field] This invention has an extremely high adhesion of the hard coating layer to the substrate surface, and the hard coating layer can be used not only for continuous cutting but also for intermittent cutting. This invention relates to a cutting tool member made of a surface-coated tungsten carbide-based cemented carbide (hereinafter abbreviated as a coated carbide cutting tool) that exhibits excellent performance over a long period of time because peeling is suppressed. .

[Conventional technology]

Conventionally, Ti carbides, nitrides, and carbonitrides (hereinafter referred to as WC) have been deposited on the surface of a tungsten carbide (hereinafter referred to as WC)-based cemented carbide substrate by chemical vapor deposition (CVD) or physical vapor deposition (PVD). TiC, TiN, and TiC
A single layer or a multilayer of two or more of the following (indicated by N),
and aluminum oxide (hereinafter AJ720) as necessary.
A coated carbide cutting tool formed by forming a hard coating layer with an average layer thickness of 1 to 10 μm consisting of the uppermost layer (indicated by No. 3) is used for continuous cutting or interrupted cutting of steel and the like.

[Problem 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 as a result, there is a tendency for cutting to be performed under harsh conditions. At present, they tend to peel off and have a relatively short service life.

[Means to solve the problem]

Therefore, from the above-mentioned viewpoint, the present inventors focused on the conventional coated carbide cutting tool, and in order to suppress the peeling of the hard coating layer from the base surface, firstly, the present inventors focused on the conventional coated carbide cutting tool. When we investigated the reasons why the hard coating layer of tools is likely to peel off, we found that one of the reasons was that the coefficient of thermal expansion of the hard coating layer and the base material was significantly different, that is, the TI constituting the hard coating layer
The thermal expansion coefficient of C is 8.6X106/'C, and that of TiN is 9
, 8×10 /'C1 and the same TiCN is 9.4Xl
This is due to the fact that the WCC cemented carbide substrate has a temperature of about 5X106/'C, whereas the
One is that during the formation of the hard coating layer, the constituent components of the substrate (in most cases Go, henceforth referred to as Co) diffuse and move into the hard coating layer together with the W component dissolved therein, and the substrate after the Co transfer As a result of conducting research to solve these problems, we came to the conclusion that bores are formed on the surface and that the formation of these bores also causes a decrease in the adhesion of the hard coating layer. , a single layer consisting of one of Zr carbides, nitrides, and carbonitrides (hereinafter referred to as ZrC, ZrN, and ZrCN, respectively) is provided as an underlayer between the hard coating layer and the substrate. When interposed in a relatively thin layer with respect to the underlying layer, the ZrC constituting the base layer has a thermal expansion coefficient of 7, OXIO/℃, and ZrC.
N is 7.9X10-6/'C1=6 and ZrCN is 7.9X10-6/'C1=6. As GXlo 6/℃,
Since the hard coating layer has an intermediate coefficient of thermal expansion between the hard coating layer and the substrate, it not only alleviates the thermal strain caused between the hard coating layer and the substrate due to the high heat generated during cutting, but also reduces the thermal expansion coefficient between the hard coating layer and the substrate. has the property of inhibiting the diffusion and movement of CO in the substrate, so that the formation of bores on the surface of the substrate due to the diffusion and movement of CO is prevented.
Coupled with the fact that the base layer itself has excellent adhesion to the substrate and the hard coating layer, it is hard enough not only for high-speed cutting, heavy cutting such as high feed and high depth of cut, but also for interrupted cutting under severe conditions. It was discovered that peeling of the coating layer was prevented and excellent wear resistance was exhibited over a long period of time.

This invention has been made based on the above findings, and has an average layer thickness of a single layer of one of ZrC, ZrN, and ZrCN on the surface of a WCC cemented carbide substrate:
TiC, TiN through a base layer of 0.05 to 1
and a single layer of one kind or a multilayer of two or more kinds of TiCN, and if necessary A i! The coated carbide cutting tool is characterized by forming a hard coating layer having an average layer thickness of 1 to 10 μm and consisting of the most two layers of 20 μm.

In addition, in the coated carbide cutting tool of the present invention, the average layer thickness of the base layer is set to 0.05 to 11EII because the layer thickness is 0.0! If the layer thickness is less than 1 ozm, the desired thermal strain relaxation effect and Co diffusion movement inhibiting effect cannot be obtained;
μI is sufficient, and if the layer thickness is thicker than this, the underlying layer itself is relatively soft, so the wear resistance of the cutting tool member itself decreases. The reason why the average layer thickness of the coating layer is set to 1 to 10 IU is because if the layer thickness is less than 1 u1n, the desired wear resistance cannot be ensured, and on the other hand, if the content is 10! ErI
This is because if the hard coating layer itself exceeds this, chipping or chipping will occur in the hard coating layer itself.

〔Example〕

Next, the coated carbide cutting tool of the present invention will be specifically explained using examples.

As raw material powders, WC powder, various metal carbide powders, composite metal carbide solid solution powders, and Co powders, all of which have average particle diameters within the range of 0.5 to 1 OurrI, were prepared. The mixture was mixed in a ball mill for 72 hours, dried, and then press-molded into a green compact at a pressure of 1,5 tons/(!J). 90°C to a predetermined temperature within the range of 1350 to 1500°C in vacuum.
The sintered body is sintered under conditions of holding for a minute to obtain a sintered body having substantially the same composition as the compounded composition, and this sintered body is cut to form an indexable tip whose base shape corresponds to JIS 5NG432. Then, coated carbide cutting tools 1 to 9 of the present invention are prepared by forming a base layer and a hard coating layer shown in Table 1 on the surface of this WCC cemented carbide base chip using a normal chemical vapor deposition method. manufactured respectively.

For comparison, conventional coated carbide cutting tools 1 to 9 were manufactured under the same conditions except that no underlayer was formed.

For the various coated carbide cutting tools obtained as a result, the critical peeling load was measured using a scratch tester, and the following results were obtained: Work material: SN CM439 (hardness: HB 260)
) round bar, cutting speed: 200 m/min.

Feed: 0.3 mm/rev.

Depth of cut + 1.5 mm.

Cutting time: 15 minutes.

Dry continuous high-speed cutting test of steel under the following conditions, and workpiece material: S N CM439 (hardness: HB31.0) grooved round bar cutting speed: 140 rn/mtn feed 20, 25 mm/rev, .

A dry interrupted cutting test was conducted on steel under the condition of depth of cut: 2 mm. In the former, the flank wear width and rake face wear depth of the cutting edge were measured, and in the latter, the cutting time until chipping occurred on the cutting edge was measured. measure,
Table 1 shows the average value of the number of 10 test cutting edges.

〔Effect of the invention〕

From the results shown in Table 1, the coated carbide cutting tool 1 of the present invention
-9 all have intermediate thermal expansion coefficients between the substrate and the hard coating layer, and the hard coating layer has strong adhesion by forming a base layer that prevents the diffusion and movement of CO in the substrate to the hard coating layer. It is strongly bonded to the substrate surface, and peeling of the hard coating layer is significantly suppressed during cutting, so it has excellent wear resistance not only in high-speed cutting but also in interrupted cutting under severe conditions. In contrast, in the conventional coated carbide cutting tools 1 to 9 in which the underlayer is not formed, Co in the base material diffuses into the hard coating layer. In addition to movement, rapid changes between the substrate and the hard coating layer tend to cause peeling of the hard coating layer, and it is clear that this is likely to cause chipping, especially in interrupted cutting.

As mentioned above, in the coated carbide cutting tool of the present invention, the adhesion of the hard coating layer to the substrate surface is extremely high, and the peeling of the hard coating layer is prevented not only when used for continuous cutting but also especially when used for interrupted cutting. Since the cutting speed is significantly suppressed, it has industrially useful properties such as excellent cutting performance over an extremely long period of time.

Claims (2)

[Claims] (1) Zr on the surface of the tungsten carbide-based cemented carbide base
Average layer thickness consisting of a single layer of one of Ti carbides, nitrides, and carbonitrides: Through a base layer of 0.05 to 1 μm, one of Ti carbides, nitrides, and carbonitrides is Average layer thickness consisting of one type of single layer or two or more types of multilayer: 1 to 1
A surface-coated tungsten carbide-based cemented carbide cutting tool member formed with a hard coating layer of 0 μm. (2) Zr on the surface of the tungsten carbide-based cemented carbide base
Average layer thickness consisting of a single layer of one of Ti carbides, nitrides, and carbonitrides: Through a base layer of 0.05 to 1 μm, one of Ti carbides, nitrides, and carbonitrides is A cutting tool member made of a surface-coated tungsten carbide-based cemented carbide formed by forming a hard coating layer having an average layer thickness of 1 to 10 μm and consisting of one type of single layer or two or more types of multiple layers and an uppermost layer of aluminum oxide.