JPH0712565B2 - Tungsten carbide based cemented carbide cutting tool - Google Patents

Description

The present invention relates to a cutting tool made of a tungsten carbide based cemented carbide having excellent wear resistance.

[Conventional technology]

Conventionally, as a cutting tool, tungsten carbide (hereinafter referred to as WC) is the main component, and hard materials such as 4a, 5a and 6a group carbides, nitrides and carbonitrides of the periodic table A cutting tool made of WC-based cemented carbide in which the hard phase is bonded with a metal such as Co has been put to practical use.

[Problems to be solved by the invention]

However, recently, as the strength and hardness of the work material are gradually improved and the efficiency of cutting is also required to be increased, the emergence of a cutting tool having further excellent wear resistance is desired. However, the conventional WC-based cemented carbide cutting tool as described above has a problem in that the wear resistance sufficient to meet the above demand has not yet been sufficiently obtained.

[Findings based on research]

In view of the above problems, the present inventors have conducted various studies to develop a cutting tool made of a WC-based cemented carbide with excellent wear resistance, and as a result, the WC-based cutting tool that is a constituent material of the cutting tool. The cemented carbide is made of any one or more of 4a, 5a and 6a carbides, nitrides and carbonitrides of the periodic table, or two or more of any of these compounds. Consisting of a solid solution consisting of, or a continuous reticulated hard phase consisting of a mixture of these compounds and a solid solution, and composed of a massive WC-based cemented carbide, and the network of the reticulated hard phase is said massive WC-based cemented carbide It was found that, when the WC-based cemented carbide in the form of a block is filled with the above structure to form a structure in which the reticular hard phase is bonded, the WC-based cemented carbide exhibits remarkably excellent wear resistance.

[Means for solving problems]

This invention was invented based on the above findings, in the cutting tool made of WC-based cemented carbide, the WC-based cemented carbide is a carbide, nitride of 4a group, 5a group and 6a group of the periodic table. And any one or more of carbonitrides,
Alternatively, a solid solution consisting of any two or more of these compounds, or a continuous reticulated hard phase composed of a mixture of these compounds and a solid solution, and a massive WC-based cemented carbide, and the reticulated hard The mesh of the phase is the massive WC
It is characterized in that it is filled with a base cemented carbide and has a structure in which this massive WC-based cemented carbide is bonded with the network hard phase.

[Specific Description of the Invention]

(1) Reticulated hard phase Examples of materials constituting the reticulated hard phase include TiC, WC, and T.
4a group, 5a of the periodic table such as aC, NbC, TiN, TaN, TiCN, TaCN
Group 6 and 6a carbides, nitrides, carbonitrides, solid solutions of two or more of these compounds, eg (Ti, W) C, (Ta, N
b) C, (Ti, W, Ta) C, (Ti, W) CN and mixtures of such compounds with solid solutions can be used.

As shown in the schematic explanatory view in FIG. 1, when the average thickness of the reticulated hard phase 1 is less than 2 μm, no improvement in wear resistance is obtained in the cutting tool, while it is 30 μm.
If it exceeds, the toughness to be provided as a cutting tool is remarkably lowered, so that the average thickness is preferably 2 to 30 μm in general.

(2) Bulk WC-based cemented carbide As the material for the bulk WC-based cemented carbide, any known WC-based cemented carbide can be used. For example, WC or WC Small amount of TiC, TaC, NbC, TiN,
(Ti, W) C, (Ti, W) CN, (Ti, W, Ta) C, TiCN, TaCN
In addition to the above, it is possible to use a WC-based cemented carbide in which this is combined with one or more of Co, Ni, and Fe.

Similarly, as shown in the explanatory view of FIG. 1, this massive WC
When the average lengths of the base cemented carbide 2 in the directions of the minor axis a and the major axis b are less than 30 μm and less than 50, respectively, the proportion of the reticulated hard phase 1 becomes relatively large and the toughness of the tool remarkably decreases. When the average lengths in the directions of the minor axis a and the major axis b exceed 300 μm and 500 μm, respectively, conversely, the proportion of the reticulated hard phase 1 is relatively insufficient, and the wear resistance cannot be improved. The average lengths of the base cemented carbide in the minor axis direction and the major axis direction are 30 to 300 μm and 50 to 500 μm, respectively.
It is preferably m.

In addition, such a reticular hard phase 1 and massive WC-based cemented carbide 2
The WC-based cemented carbide of the present invention consisting of and, by providing various suitable coating layers thereon, naturally exhibits even greater effects as a base material for a so-called coated cemented carbide cutting tool. .

(3) Manufacture of WC-based cemented carbide The WC-based cemented carbide that is a constituent material of the cutting tool of the present invention is
First, appropriately prepared raw material powders such as WC powder, TiC powder, TaC powder, TiN powder, and Co powder are blended so as to have a predetermined WC-based cemented carbide composition and mixed, and then this mixed powder has a predetermined particle size. Granules, and then, on the surface of the granules, for example, the hard phase powder slurried with alcohol or the like is applied, and after drying, the hard phase powder-applied granules thus prepared are pressed into a powder compact Can be manufactured by press molding and sintering the green compact.

〔Example〕

Next, the WC-based cemented carbide cutting tool of the present invention will be specifically described by way of examples.

As a raw material powder, WC powder having an average particle diameter of 5 μm, 1
Prepare TiC powder of 1 μm, TaC powder of 1 μm, NbC powder of 1 μm, TiN powder of 1.5 μm, and Co powder of 1 μm, and mix these raw material powders with the composition shown in Table 1, respectively. After wet mixing for 72 hours in a ball mill,
From this mixed powder, a spray dryer was used to granulate fine particles each having an average particle size shown in Table 1, and then the surfaces of these fine particles were made into a slurry with alcohol. The average particle diameter shown in the table is 1 μm, and the hard phase powder is also applied with the average thickness shown in Table 1, dried, and then pressed at a pressure of 10 Kg / mm ² with the shape specified in ISO standard SNMN120408. The WC-based cemented carbide cutting tools 1 to 7 of the present invention were manufactured by press molding into powder and sintering the green compact at a temperature of 1380 ° C. in a vacuum of 1 × 10 ⁻³ torr.

The WC-based cemented carbide cutting tools 1 to 7 of the present invention obtained as a result
When the average lengths in the minor axis and major axis directions of the massive WC-based cemented carbide and the average thickness of the hard phase were measured, the results shown in Table 1 were obtained.

Also, for the purpose of comparison, the above raw material powders were blended so as to have the blending composition shown in Table 1, and these blended powders were wet mixed in a ball mill for 72 hours and dried, and then 10 kg
Press molding into a green compact with the same shape as above with a pressure of / mm ² ,
Next, this green compact was also subjected to 1450 in a vacuum of 1 × 10 ^-3 torr.
Conventional WC-based cemented carbide cutting tools 1 and 2 were manufactured by sintering at a temperature of ℃.

Next, the above-mentioned present invention a cutting tool 7 and a conventional cutting tool 1-2, Workpiece: JIS · SNCM439 (Hardness: H _B 310) roundwood of cutting speed: 120 m / min, Feed: 0.25 mm / rev., depth of cut: 2 mm, perform cutting test 1 for continuous dry cutting of steel, and measure the cutting time until the flank wear width reaches 0.4 mm, that is, the service life of the cutting tool. , Work material: FC30 (hardness: H _B 160) round material, Under the conditions of cutting speed: 140 m / min, feed: 0.3 mm / rev., Depth of cut: 1.5 mm, a cutting test 2 in which cast iron was continuously cut dry was carried out, and the service life of the cutting tool was similarly measured.

The service life of each cutting tool obtained in the above cutting test is also shown in Table 1.

〔The invention's effect〕

From the results shown in Table 1, it is clear that the WC-based cemented carbide cutting tools 1 to 7 of the present invention exhibit a significantly longer service life than the conventional WC-based cemented carbide cutting tools 1 and 2. ,
These results show that the WC-based cemented carbide cutting tool according to the present invention has remarkably excellent wear resistance as compared with the conventional one.

As is clear from the above-mentioned results, the WC-based cemented carbide that constitutes the cutting tool of the present invention is a lump (granular) WC-based cemented carbide that surrounds the net-like hard phase to integrally integrate those lumps. Since it has a combined structure, it exhibits extremely excellent wear resistance, and has an industrially useful effect that a remarkably long service life is obtained even when cutting various work materials.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing the structure of a WC-based cemented carbide that constitutes the cutting tool of the present invention. In the figure, 1 ... continuous reticulated hard phase, 2 ... massive WC-based cemented carbide.

Claims (3)

[Claims] 1. A tungsten carbide based cemented carbide cutting tool, wherein the tungsten carbide based cemented carbide is any one of carbides, nitrides and carbonitrides of Groups 4a, 5a and 6a of the periodic table. 1 or 2 or more, or a solid solution composed of any 2 or more of these compounds, or a continuous reticulated hard phase composed of a mixture of these compounds and a solid solution, and massive tungsten carbide-based cemented carbide And a network of the reticulated hard phase is filled with the bulk tungsten carbide-based cemented carbide, having a structure in which the bulk tungsten carbide-based cemented carbide is bonded in the reticulated hard phase, The cutting tool made of the above-mentioned tungsten carbide based cemented carbide. 2. The tungsten carbide based cemented carbide cutting tool according to claim 1, wherein the reticulated hard phase has an average thickness within the range of 2 to 30 μm. 3. A dimension in which the bulk tungsten carbide-based cemented carbide has an average length in the minor axis direction of 30 to 300 μm and an average length in the major axis direction of 50 to 500 μm. The tungsten carbide-based cemented carbide cutting tool according to claim (1) or (2), characterized in that: