JPH04152004A - Cutting tool - Google Patents

Abstract

PURPOSE:To enhance heat resistance and wear resistance, to improve cutting- edge workability and to prolong the life of a cutting tool in the cutting tool such as a drill, by adopting the composition mainly consisting of a Ti nitride to the end part thereof, and by using a fine-grain WC alloy to the root part thereof. CONSTITUTION:The cutting-edge part having a groove part of a length L and the shank part of the cutting tool are made up of different compositions. Denoting by part A the range of 0.1 to 1.0L from the end of the tool and by part B the shank part, the compositions of the parts A, B are determined to be within the following range. The part A contains 5 to 40% WC and/or MoC, 5 to 30% Co and/or Ni, 0.1 to 10% TaC and/or (Ta,Nb)C, and the remainings of at least one kind selected from the group consisting of TiC, TiN, and Ti(C,N) and unavoidable impurities. The part B contains 5 to 30% Co and/or Ni, 0.1 to 2.O% of at least one kind selected from the group consisting of Cr3C2, VC, MoC, and TaC, and 0.1 to 2.0% the remainings of WC of average grain size of 3mum or less and unavoidable impurities.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to cutting tools such as drills, end mills, and reamers, and in particular, by combining different materials, it has improved wear resistance, chipping resistance, and breakage resistance. This invention relates to an improved cutting tool.

[Prior art] WC-based and TiC-based hard alloys are generally produced by powder metallurgy, and are widely used as cutting tools such as drills, end mills, and reamers, wear-resistant tools such as bits and rolls, and mining tools. ing.

The above hard alloys are used as cutting tools for high-hardness materials such as iron and rocks, and are wear-resistant and? # Since it is used as a hammer tool, extremely high wear resistance is required, and it has a Vickers hardness of 1.
It is a high hardness material with a hardness exceeding 0.000.

However, in general, the higher the hardness, the more brittle the material becomes, and the above hard materials have the disadvantage of being inferior in toughness compared to high-speed steel (hereinafter referred to as high-speed steel), which is commonly used as a wear-resistant cutting tool. was. On the other hand, the HIP method was developed to completely eliminate the bore, which was a drawback of powder metallurgy, and with the invention of ultrafine cemented carbide, hard materials with toughness close to that of high speed steel were commercialized. As a result, WC-based hard materials have begun to become popular even in milling tools such as drills and end mills, where high-speed steel tools have traditionally been the mainstream. It has become possible to meet recent needs for high-performance machining, such as improved machining efficiency and higher precision through cutting.

However, even with the above-mentioned hard materials, there is a problem in that the tool life varies due to sudden breakage, chipping, etc. depending on the usage conditions, and improvement of reliability remains an issue.

Below, a drill will be explained as a typical cutting tool.

It is known that the problem of chipping and breaking of drills made of hard materials is affected by both the shape and the material. In terms of shape, drills have been developed that solve the problem of chipping by devising the shape of the chisel part. In addition, in order to improve the resistance to chipping and breaking from the viewpoint of material quality, an effective means for boat fishing is to increase the transverse rupture strength and improve the toughness.

However, wear resistance and toughness are contradictory properties, and ultrafine grained alloys with excellent toughness are no exception. Therefore, the currently widely used carbide drills have been devised from the material standpoint, using a relatively tough P30 equivalent carbide material as the tool material, and coating the cutting edge with TiN etc. to extend the cutting life to practical use. Although this has been improved to the level that is possible, there is a problem in that the coating part easily peels off, and variations in lifespan are still a problem.

[Problems to be Solved by the Invention] The present invention has been made focusing on the above-mentioned circumstances, and it is possible to improve wear resistance by combining different materials in hard materials where breakage resistance and chipping resistance are problematic. The aim is to provide a cutting tool with excellent reliability by simultaneously increasing chipping resistance and breakage resistance.

[Means for solving the ff problem] The first invention of the cutting tool of the present invention that achieves the above object is a cutting tool having a long groove and having different compositions in a cutting edge portion and a shank portion, the tool 0.1 from the cutting edge
When the range of L to 1.0L is defined as part A and the shank part is defined as 8 parts, the gist is that the compositions of parts A and 8 are defined in the following ranges.

[Part A WC and/or MOC: 5-40% CO and/or Ni: 5-3o% TaC and/or (Ta,
Nb) C: 0.1-10% Balance: one or more selected from the group consisting of TiC, TiN, Ti (C, N) and inevitable impurities.

[Part B] Co and/or Ni: 5 to 30% Crs One or more selected from the group consisting of C2, VC, MoC, and TaC = 0.1 to 2.0% Balance: Average particle size 3
WC and unavoidable impurities below μm.

In addition, the composition of part A above includes V(C,N), Cr(C,N)
, Hf (C,N), B (C,N).

One or more selected from the group consisting of Nb (C, N) and Zr (C, N) may be contained in an amount of 0.1 to 5%,
Or/and the composition of part B is further TiC.

1 selected from the group consisting of TaC, (Ta, Nb)C
Species or more = 30% or less, and/or Hf (C, N),
B (C,N), Nb (C,N).

It may contain 0.1 to 5% of one or more selected from the group consisting of Zr (C, N) carbonitride, TiN, and TaN.

[Function] The composition of part A on the tip side of the cutting tool according to the present invention is intended to improve the life of the cutting tool, and by adopting a composition mainly composed of Ti-based carbonitride, heat resistance, This is designed to improve wear resistance and extend the life of cutting tools.

The reasons for limiting each component will be explained below.

WC and/or MoC are added for the purpose of improving heat resistance, but if it is less than 5%, the effect will not be sufficiently obtained, while if it is too much, wear resistance will be low and the desired cutting tool life cannot be achieved, so 40% was set as the upper limit.

If CO and/or Ni is less than 5%, chipping will occur on the cutting edge, so add 5% or more, but if it is too much, the wear resistance will deteriorate and the desired cutting tool life cannot be achieved, so add 30%.
was set as the upper limit.

TaC and/or (Ta, Nb)C are added for the purpose of improving heat resistance, but if it is less than 0.1%, sufficient effect will not be exhibited, and if it exceeds 15%, chipping will become a problem and the desired life will not be achieved. Since it is not possible, the TaC content is 0.1 to 1.
It was set at 5%.

In addition to the above, V, Cr, Hf, and B are added for the purpose of suppressing grain growth of fine carbonitrides during sintering.

Carbonitride of one or more elements selected from the group consisting of Nb and Zr may be contained in an amount of 0.1% or more, but if it is too large, it will have a negative effect on toughness, so it is desirable to keep the upper limit at 5%. .

Next, in the cutting tool of the present invention, the composition of part B, which is the root side, is intended to improve the breakage resistance of the cutting tool, and by adopting a composition mainly composed of fine W-based carbide, the toughness can be improved. It was planned.

If the Co and/or Ni content is less than 5%, the toughness will be insufficient and the breakage resistance will not be effective. On the other hand, even if it exceeds 30%, the toughness decreases, so the content of CO and Ni should be 5 to 5%.
It was set at 30%.

Cr, C2, VC, MoC and TaC are compounds that act as grain growth inhibitors during sintering, and their 1f! If the above content is less than 0.1%, the effect of suppressing grain growth will not be exhibited, and the average grain size of WC will exceed 3 μm or abnormally grown grains will be formed due to sintering, resulting in decreased toughness and breakage resistance. cannot be effective. On the other hand, if the amount exceeds 2%, grain growth suppressing effects can be exhibited, but due to the large amount added, depending on the temperature during sintering and cooling, crystallized substances may be formed that impair toughness, making it impossible to demonstrate the effect, so 2% was set as the upper limit. .

If the average particle diameter of WC exceeds 3 μm, the toughness will deteriorate and the breakage resistance will not be effective, so the upper limit was set at 3 μm.

In addition to the above, for the purpose of preventing thermal damage of chips discharged through the groove during cutting, improving heat resistance, and suppressing grain growth, in addition to the above, a material selected from the group consisting of TiCTaC and (Ta, Nb)C is used. One or more types may be contained.

However, if it is too large, the toughness will deteriorate, so it is desirable that the upper limit is 30%.

In addition, Hf and B are added for the purpose of suppressing grain growth.

One or more selected from the group consisting of carbonitrides of Nb and Zr and nitrides of Ti and Ta may be contained in an amount of 0.1% or more; however, if it is too large, it will have a negative effect on toughness, so it should not exceed 5%. It is preferable that

In addition, for the purpose of increasing the integrity of the above A part and B part,
It is preferable that the joint between parts A and B has a mixed composition of parts A and B.

[Example〕 First, the first invention will be explained based on examples.

Example I The raw material powder for part A (hereinafter sometimes referred to as A powder) was 0.8 μm Ti (C,N).

T i C, WC, 1, 3 μm MoC, TaC, 1,
Co and Ni of 0 μm are used, and W of 0.6 to 1.5 μm is used as the raw material powder for part B (hereinafter also referred to as B powder).
C, 1.3 μm 1 of TaC, VC.

Part A above using Crs C2, 1,0 μta of CO.

Each of the raw material powders in Part B was subjected to the following treatments.

First, the above raw material powders were blended to have the final composition shown in Table 1, mixed in an organic solvent for 8 hours using an attritor, and then dried and granulated.

Using the obtained mixed powder, first a predetermined amount of A powder accumulated in a hopper was put into a molding die, and then a predetermined amount of B powder was put into the mold and compaction was performed at 1.5 ton/cm''. .

After dewaxing and semi-baking the thus obtained molded body, it was subjected to a semi-baking process to form a drill-shaped material. This half-baked amount is approximately 14 in a vacuum atmosphere of I Torr.
After sintering at 00℃ for 1 hour, sintering at 1000 atm under Ar atmosphere
A sintered body was obtained by performing HIP treatment at 350°C for 1 hour. The sintered body is machined, and the area from the cutting edge to 20+m is A composition, and the rest is B composition, 6.0 amφ and 10.0ma.
A +φ drill was manufactured and the conventional carbide coating (T
iN) The performance of drills and hole-cutters was compared based on the number of possible holes. The results are shown in Table 2.

Example 2 The starting raw material powder was 0.8μ Ti (C,N).

T i C, WC, 1, 3 μm MoC, TaC, 1,
Co and Ni of 0 μm0 are used as powder, and 0.5 to 0.
8μm WC, 1.3μm TaC, Cr, C2,1,
0μ Co was used as B powder. A above.

End mill materials were obtained by the same manufacturing method as in Example 1, except that the B powders were blended so as to obtain the final compositions shown in Table 3.

This was machined, and a 4-flute end mill with a diameter of 110l1φ and a helix angle of 30° was manufactured, with the blade part 22III having composition A and the rest having composition B. Cutting was performed under the following conditions, and the total cutting The length and surface roughness at a cutting length of 8 m were measured.

An ultrafine particle carbide end mill was used as a comparison material.

Cutting speed = 70 m/min Feed: 0.07ma+/blade Depth of cut 2nd radial direction −〇, OFvmφ Axial direction -15a+m Cutting material: 555C (H8=190) Cutting method: down cut, wet method The results are shown in Table 4.

Table 3: Example 3 The raw material powders used in Example 2 were blended so that the final composition would be Invention Alloy 1'EL and Comparative Alloy 1 shown in Table 3, and a reamer material was obtained using the same manufacturing method as Example 1. Ta.

These were machined to produce a 20 mm diameter reamer in which the cutting edge of the material of the present invention had composition A and the rest had composition B, and reaming was performed under the following conditions.

Cutting speed: 1500++m/minute feed Re: 0.4a+m/Blade cutting length: 25ma+Through reaming: 0.2a+m Work material: 550C (Ha "179) Cutting method: Wet 1.5, 50, 500th hole Table 5 shows the measured ranges of surface roughness, roughness, and roundness.

It can be seen that the surface roughness and roundness values of the tires using the materials of the present invention in Table 1 are much smaller than those of the comparative materials, indicating that they have excellent wear resistance.

[Effects of the Invention] Since the present invention is configured as described above, a cutting tool having excellent wear resistance, chipping resistance, and breakage resistance can be provided.

Furthermore, since a fine-grained WC alloy with good grindability is used on the root side to solve the problem of grindability that occurs with TiC-based single alloys, it is possible to perform moon cutting on the same level as with conventional cemented carbide.

Claims (2)

[Claims] (1) A cutting tool having a groove of length L and having different compositions in the cutting edge and the shank, the cutting tool having a groove with a length L, the cutting tool having a groove having a length L and having different compositions in the cutting edge and the shank.
．． A cutting tool characterized in that the compositions of parts A and B are defined in the following ranges, where part A is the range of 1L to 1.0L, and part B is the shank part. [Part A] WC and/or MoC: 5 to 40% (meaning of weight %, same below) Co and/or Ni: 5 to 30% TaC and/or (Ta, Nb)C: 0.1 to 10
% Remainder: one or more selected from the group consisting of TiC, TiN, Ti (C, N) and unavoidable impurities. [Part B] Co and/or Ni: 5-30% One or more selected from the group consisting of Cr_3, C_2, VC, MoC, TaC: 0.1-2% Remaining part: WC with an average particle size of 3 μm or less and Unavoidable impurities. (2) The cutting tool according to claim (1), wherein the composition of part A further comprises V(C,N), Cr(C,N), Hf(C,
N), B (C, N), Nb (C, N), Zr (C, N)
One or more selected from the group consisting of: 0.1 to 5%/And the composition of part B further includes TiC, TaC, (Ta, Nb)C
One or more selected from the group consisting of: 30% or less, and/or Hf (C, N), B (C, N), Nb (C,
A cutting tool containing 0.1 to 5% of one or more selected from the group consisting of N), Zr (C, N), TiN, and TaN.