JP2841749B2 - Boron carbide coated cutting tools - Google Patents

Description

The present invention relates to the cutting and drilling of non-ferrous metals and their alloys which do not form compounds with carbon and boron, such as copper and aluminum, and synthetic resins. For example, the present invention relates to a boron carbide coated cutting tool used in the present invention, for example, an indexable insert for Al cutting, a miniature drill for drilling a printed circuit board, and the like.

[Conventional technology]

In general, boron carbide is considered to be from BC to B ₆ C, and among them, B ₄ C is the hardest, having a Vickers hardness of 4000 to 5000, and therefore, conventionally, boron carbide is used for rotating parts, It is used for coating on exterior parts such as watch cases, glass products, etc., and is useful for improving abrasion resistance and preventing the occurrence of surface flaws (JP-A-50-155480, JP-A-50-155480).
See JP-A-54-15481 and JP-A-63-203760).

[Problems to be solved by the invention]

However, B ₄ C, the weak adhesive strength with respect to the tungsten carbide based cemented carbide base material surface, a cutting tool forming the B ₄ C coating tungsten carbide based cemented carbide base material surface, B ₄ C during the cutting There was a problem that the coating layer was easily peeled.

[Means for solving the problem]

Therefore, the present inventors have solved the above-described problems,
Adhesion strength superior B ₄ C coating tungsten carbide based cemented carbide cutting results to conducted research to obtain a tool, Ti, Zr, and Hf carbides, nitrides, among carbonitrides and borides as well as their solid solutions It has been found that a coating layer composed of a single layer or a plurality of layers composed of one or more compounds of the formula (1) has excellent adhesion strength to the B ₄ C coating layer.

The present invention has been made based on such findings, and includes a method of forming a carbide, nitride, carbonitride, and boride of Ti, Zr, and Hf on a surface of a tungsten carbide-based cemented carbide base material, and a mixture thereof. B ₄ via a single-layer or multiple-layer underlayer composed of one or more compounds in the solid solution
A cutting tool comprising forming a C coating layer, the B ₄ C coating layer has a thickness of: having a 0.5 to 3.0 [mu] m, the base layer has a thickness of: boron carbide coatings with 0.5~5.0μm Cutting tools are unique.

Was a 0.5~3.0μm the thickness of the B ₄ C coating layer, 0.5
If the thickness is less than μm, the hardness of B ₄ C as the outermost layer cannot be fully utilized, while if it exceeds 3.0 μm, the toughness is significantly reduced and the peeling is remarkably easy.

One or two of carbides, nitrides, carbonitrides and borides of Ti, Zr and Hf, and solid solutions thereof.
It is known that an underlayer composed of a single layer or a plurality of layers composed of at least one kind of compound has excellent adhesion to a tungsten carbide-based cemented carbide base material, and has a thickness of 0.5%.
The reason why the thickness is set to about 5.0 μm is that if the thickness is less than 0.5 μm or exceeds 5.0 μm, the effect of increasing the adhesion to the B ₄ C coating layer as the underlayer is not sufficiently obtained, and the layer is easily peeled.

〔Example〕

Next, the boron carbide-coated cutting tool of the present invention will be specifically described based on examples.

Example 1 Co: 9% by weight, balance: WC and unavoidable impurities,
WC-based cemented carbide tip has the shape of PGN120308 and respectively mean flow diameter,: 3 [mu] m of B ₄ C powder, TiB ₂ powder was hot pressed respectively, also Ti powder, (Ti + Hf) powder,
(Ti + Zr) powder was sintered diameter: 100 mm, thickness: 10 mm B ₄ C target having a dimension of, TiB ₂ target, Ti target, (Ti, Hf) target, were prepared (Ti, Zr) respectively Target A plurality of WC-based cemented carbide chips and predetermined targets were set in an arc ion plating apparatus. Next, the pressure in the arc ion plating apparatus was maintained at a vacuum of 5 × 10 ⁻⁵ Torr, and then the WC-based cemented carbide tip was heated to about 500 ° C. by an internal heater.
And a negative voltage of -800 V was applied.

On the other hand, a plurality of targets provided in the arc ion plating apparatus were used as cathodes, and the surface of the targets was physically cleaned by setting the arc current flowing on the surfaces of these targets to 110 A. Subsequently, the tip of the WC-based cemented carbide set in the arc ion plating apparatus was set to −300 V, and a predetermined reaction gas, for example, N ₂ , C ₂ H ₂ or the like was introduced into the arc ion plating apparatus. Pressure: 5 × 10
Underlayer shown in Table 1 in a ^-3 Torr vacuum atmosphere
B ₄ C coating layer present invention the boron carbide coating WC-based cemented carbide chips 1-9 with Comparative boron carbide coated WC-based cemented carbide chip 1-5, and conventional boron carbide coated WC-based cemented carbide tip Was prepared.

The resulting boron carbide coated WC-based cemented carbide tips 1-9, the comparative boron carbide-coated WC-based cemented carbide tips 1-5, and the conventional boron carbide-coated WC-based cemented carbide tips thus obtained A continuous dry cutting test was carried out under the following conditions, and when the flank wear width of the insert reached 0.3 mm, the life was measured as the life, and the results are shown in Table 1. Was.

Continuous cutting test conditions Work material: cylindrical body made of Al alloy containing 12% Si, diameter: 250mm, cutting speed: 500m / min, feed: 0.2mm / rev., Depth of cut: 1.5mm, and carbonization of the present invention described above Using 10 pieces each of boron coated WC-based cemented carbide chips 1 to 9, comparative boron carbide coated WC-based cemented carbide chips 1 and 10, and conventional boron carbide coated WC-based cemented carbide chips, the following conditions , A two-minute intermittent dry cutting test was performed, and the number of chipped chips out of the ten chips was measured. The results are shown in Table 1.

Intermittent cutting test conditions Work material: A cylindrical body with a diameter of 200 mm, which is made of an Al alloy containing 12% Si and has four grooves parallel to the axial direction, cutting speed: 180 m / min, feed: 0.2 mm / rev ., Depth of cut: 1 mm, Example 2 Co: 9% by weight, TiC: 0.5%, TaC: 0.5%, remaining: W
A miniature drill made of WC-based cemented carbide made of C and inevitable impurities and having a tip diameter of 0.6 mm was prepared. The diameter of the miniature drill prepared in Example 1 was 100 m.
m, thickness: 10 mm B ₄ C target, TiB ₂ target, Ti target, (Ti, Hf) target, as in Example 1 (Ti, Zr) in an arc ion plating apparatus used in conjunction with Example 1 Target Set to

Next, the pressure in the arc ion plating apparatus was maintained at a vacuum of 5 × 10 ⁻⁵ Torr. The miniature drill made of WC-based cemented carbide is heated to about 450 ° C and a negative voltage of 100 V is applied. On the other hand, the above-mentioned target is used as a cathode, and the surface of the target is temporarily heated to a high temperature by an arc. evaporated, cationized, TiN, TiC, TiCN, ( Ti, Hf) C, (Ti, Zr) CN, a titanium compound TiB ₂ is formed as a base layer of WC-based cemented carbide miniature drill, on which B ₄ C coating layer to produce a present invention boron carbide coated WC-based cemented carbide miniature drill 1 to 9,
Comparative boron carbide coated WC-based cemented carbide miniature drill 1
To 5, and a conventional WC-based cemented carbide miniature drill coated with boron carbide.

Using these miniature drills, 6 mm thick copper
Drill rotation speed: 700
00r.pm, drilling feed rate: 2.1m / min, drilling was performed under the condition of 2.1mm / min. The number of perforations was measured, and the results are shown in Table 2.

〔The invention's effect〕

From the results shown in Table 1, the boron carbide coated WC of the present invention was
All of the base cemented carbide tips 1 to 9 have significantly longer cutting time until the end of the life of the tip compared to conventional boron carbide coated WC based cemented carbide tips, and have even better wear resistance. You can see that. As shown in Comparative Boron Carbide Coated WC-base Cemented Carbide Chips 1 to 5, when the conditions deviate from the conditions of the present invention (in Table 1, the values deviating from the conditions of the present invention are marked with *). It is also clear that the cutting time until the end of the life of the insert is shortened.

Furthermore, from the results shown in Table 2, the miniature drills 1 to 9 made of the WC-based cemented carbide coated with boron carbide of the present invention are all smaller in miniature drills than the conventional miniature drills made of WC-based cemented carbide coated with boron carbide. It can be seen that the number of perforations until the end of the life is large, and that the material has much better wear resistance. As shown in the comparative boron carbide coated WC-based cemented carbide miniature drills 1 to 5, when the conditions deviate from the conditions of the present invention (in Table 2, the values deviating from the conditions of the present invention are marked with *). It is clear that the number of drills before the life of the miniature drill is reduced.

As described above, the boron carbide coated WC-based cemented carbide cutting tool of the present invention has excellent wear resistance, and in practical use, exhibits excellent effects over a long period of time by exhibiting excellent performance over a long period of time. Things.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-106960 (JP, A) JP-A-1-246003 (JP, A) JP-B-60-53721 (JP, B2) (58) Field (Int.Cl. ⁶ , DB name) B23B 27/14 B23B 51/00 C23C 14/06

Claims (3)

(57) [Claims] 1. A carbide, nitride, carbonitride and boride of Ti, Zr and Hf and one or more compounds of a solid solution thereof on a surface of a tungsten carbide-based cemented carbide base material. a single layer or a cutting tool that is configured through the underlying layer by forming a B ₄ C coating layer in multiple layers consisting of the B ₄ C coating layer, thickness: have 0.5~3.0μm The boron carbide-coated cutting tool, wherein the underlayer has a thickness of 0.5 to 5.0 μm. 2. The boron carbide coated cutting tool according to claim 1, wherein said boron carbide coated cutting tool is a throw-away insert. 3. The boron carbide coated cutting tool according to claim 1, wherein said boron carbide coated cutting tool is a miniature drill.