JP3331220B2 - Materials for shaft cutting tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material used for a shaft cutting tool such as a drill, an end mill, and a reamer.
The present invention relates to a shaft cutting tool material having improved wear resistance, chipping resistance, and breakage resistance by combining different materials.

[0002]

2. Description of the Related Art WC-based and TiC-based hard alloys are generally produced by powder metallurgy and widely used as cutting tools for shafts such as drills, end mills, reamers, wear-resistant tools such as bits and rolls, and tools for mining. ing.

Since the above hard alloys are used as cutting tools and wear / impact tools for high-hardness materials such as iron and rock, extremely high wear resistance is required, and high hardness exceeding Vickers hardness exceeding 1000 is required. Material.

However, in general, the higher the hardness, the more brittle the material is, and the hard material is inferior in toughness as compared with high-speed steel (hereinafter referred to as high-speed steel) generally used as a wear-resistant cutting tool. Had. On the other hand, the HIP method capable of completely eliminating pores, which has been a disadvantage of the powder metallurgy method, has been developed, and a hard material having a toughness close to that of high-speed steel has been commercialized by the invention of an ultra-fine-grain cemented carbide. As a result, WC-based hard materials have begun to be widely used in milling tools such as drills and end mills, where high-speed tools have conventionally been the mainstream, and have excellent hardness and heat resistance.
Utilizing the characteristics of high rigidity, it has come to be able to respond to the recent needs of high performance machining such as improvement of machining efficiency and high precision by high speed cutting.

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

Hereinafter, a drill will be described as a typical example of the shaft cutting tool. It is known that the problem of chipping or breaking of a drill made of a hard material depends on both the shape and the material. In terms of shape, a drill has been developed that solves the chipping problem by devising the shape of the chisel. Also, in order to improve chipping and breakage from the material side,
Generally, it is effective means to increase the bending strength and improve the toughness.

However, wear resistance and toughness are contradictory properties, and ultrafine alloys having excellent toughness are no exception. Therefore, carbide drills that are currently widely used are devised from the aspect of material and use a relatively tough P30-equivalent carbide material for the tool material and apply a coating such as TiN to the cutting edge to make the cutting life practical. Although the level is raised to a possible level, there is a problem that the coating portion is easily peeled off, and the variation in the service life is also a problem.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and in a hard material in which breakage resistance and chipping resistance are problematic, a combination of different materials is used to reduce wear resistance. The purpose of the present invention is to provide a material for a shaft cutting tool having a long tool life and excellent reliability by simultaneously improving the chipping resistance and the breakage resistance.

[0009]

The material for a shaft cutting tool of the present invention which has achieved the above object is a material for a shaft cutting tool having a cutting edge having a length L, a radius r, and a shank portion. When the range of 0.1 to 0.4r from the axis center of the blade edge portion of 0.1L to 1.0L from the blade edge is A portion, and the outer peripheral portion of the A portion is B portion, the A portion and the shank portion , And the composition of Part B is defined in the following range. [Part A and shank part] Co: 7 to 30% (meaning by weight, hereinafter the same,
May be replaced by Ni) Cr ₃ C ₂ : 12% or less of Co (however, excluding 0%, and when 50% or less of Co is replaced by Ni,
+ Ni) VC: 5% or less of Co (excluding 0%, and Co
Co + N when 50% or less of
i) Remainder: WC having an average particle size of 0.8 μm or less and unavoidable impurities [Part B] Co: 5 to 15% (however, up to 50% of Co may be replaced with Ni, and the amount of Co in Part A is based on even more than 4% less <br/> physician) TiC, TaC and (Ta, Nb) 1 or more kinds selected from the group consisting of _{C: 0.1~ 20% Cr 3 C} 2: 12% of Co The following (including 0%, C
When 50% or less of o is replaced by Ni, Co + N
i) VC: 5% or less of Co (including 0%, and 5% of Co
Co + Ni when 0% or less is replaced by Ni) The balance: WC having an average particle size of 3 μm or less (however, the WC of part A above)
The average particle size is large) and the composition of the incidental impurities also the A portion and the shank portion than, TaC, Mo ₂
Adding less than 2% of one or more selected from the group consisting of C, ZrC and HfC;
The composition of the part may further contain one or more selected from the group consisting of Mo ₂ C, ZrC and HfC.

[0010]

In the material for a cutting tool of the present invention, the composition of the portion A and the shank on the shaft center is intended to improve the breakage resistance of the cutting tool. By adopting it, the toughness is improved.

[0011] Co plays a role of a binder phase. If the content is too small, the toughness becomes insufficient and the effect on the breakage resistance cannot be exerted. On the other hand, even if it exceeds 30%, the toughness is reduced.
Was 5 to 30%. Note that Ni has the same effect as Co.
(Hereinafter, when Co is used, it is assumed that 50% or less is replaced with Ni.)

Cr ₃ C ₂ is a compound that acts as a grain growth inhibitor during sintering. If the amount is too small, the effect of suppressing grain growth is not exhibited, and the average particle size of WC is 3 μm due to sintering.
Or abnormally grown particles are formed, toughness is reduced, and the effect on breakage resistance cannot be exhibited. On the other hand, if it exceeds 12% with respect to Co, the effect of suppressing grain growth can be exhibited,
Since the amount of addition is large, a crystallized substance that impairs toughness is generated depending on the temperature during sintering or cooling, and the effect cannot be exhibited.

VC has the same effect as Cr ₃ C ₂ , but its upper limit must be 5% with respect to Co. If the average particle size of the WC exceeds 0.8 μm, the toughness is deteriorated and it is not possible to exert the effect on the breakage resistance.
Was set as the upper limit.

In addition to the above, one or two or more selected from the group consisting of TaC, Mo ₂ C, ZrC and HfC may be contained for the purpose of suppressing the grain growth of WC.
However, if the amount is too large, the toughness deteriorates. Therefore, it is desirable to set the upper limit to 2%.

The composition of the portion B on the outer peripheral side of the cutting tool according to the present invention is intended to improve the life of the cutting tool. Alternatively, by adopting a composition in which a Ta-based carbide is contained in the binder phase Co, heat resistance and wear resistance are enhanced, and the life of the cutting tool is extended.

The reasons for limiting each component will be described below. Co plays a role of a binder phase. If Co is too small, chipping occurs at the cutting edge, so that 5% or more is added. However, if Co is too large, wear resistance deteriorates and a desired cutting tool life cannot be achieved, so 15% is added. The upper limit was set.

One or more members selected from the group consisting of TiC, TaC and (Ta, Nb) C are added for the purpose of improving heat resistance. However, if less than 0.1%, a sufficient effect is not exhibited. If it exceeds 20%, chipping becomes a problem and the desired life cannot be achieved, so the content was made 0.1 to 15%.

Cr ₃ C ₂ is a compound which acts as a grain growth inhibitor during sintering. If the amount is too small, the effect of suppressing grain growth is not exhibited, and the average particle size of WC is 3 μm due to sintering.
Or abnormally grown particles are formed, toughness is reduced, and the effect on breakage resistance cannot be exhibited. On the other hand, if it exceeds 12% with respect to Co, the effect of suppressing grain growth can be exhibited,
Since the amount of addition is large, a crystallized substance that impairs toughness is generated depending on the temperature during sintering or cooling, and the effect cannot be exhibited. VC is also Cr
_It has the same effect as ₃ C ₂ , but its upper limit must be 5% with respect to Co.

In order to suppress the growth of fine carbonitrides during sintering, Mo ₂ C, ZrC and H
One or more selected from the group consisting of fC may be contained, but if too much, the toughness is adversely affected, so that the upper limit is preferably 2%.

Further, for the purpose of enhancing the integrity of the above-mentioned parts A and B, the joint between the parts A and B may be a mixed composition of the parts A and B. The ratio of the A portion and the B portion in the radial direction when the shaft cutting tool material is processed into the cutting tool may be appropriately selected depending on the type of the cutting tool, the required characteristics of the workpiece, and the like. In case A, 0.2 to 0.
It is recommended that the 3r and B parts be in the range of 0.8 to 0.7r.

[0021]

EXAMPLES As raw material powder, WC of 0.5 to 5 μm, 1.3
The following treatment was performed using μm of TiC, TaC, VC, Cr ₃ C ₂ , and 1.0 μm of Co. First, the above raw material powders were blended so as to have the final composition shown in Table 1, and mixed in an organic solvent for 8 hours using an attritor, followed by dry granulation.

Using the obtained mixed powder, a predetermined amount of the A powder accumulated in the hopper is first charged into a molding die, and then a predetermined amount of the B powder is charged so that the A powder becomes an axis portion. 1.
Compacting was performed at 0 ton / cm ² . After dewaxing and half-baking the molded body obtained in this way, half-baking was performed to obtain a drill-shaped material. About half this product
After sintering at 1300-1450 ° C for 1 hour in a vacuum atmosphere of Torr, Ar
A HIP treatment was performed at 1350 ° C. for 1 hour under an atmosphere of 1000 atm to obtain a sintered body. The sintered body is machined and 0.5 L from the cutting edge
Up to 3.0 mmφ and 6.
A 0 mm φ drill was manufactured and tested. The length of the cutting edge composed of both the A composition and the B composition is 3.0 mm.
The diameter was 12.5 mm and 6.0 mm with the φ drill and 20.0 mm with the φ drill.
The cutting conditions for the drilling test are as shown in Table 2, and the results are also shown in Table 2.

As a comparative example, one of the conditions according to the present invention was used.
Table 2 shows the results of drills obtained in the same manner as in the example except that an alloy that did not satisfy at least one was used.

[0024]

[Table 1]

[0025]

[Table 2]

Nos. 1 to 5 are examples of the present invention, and have a long drill life because they have the component composition according to the present invention. Nos. 6 to 12 are any one of the component compositions according to the present invention.
This is a comparative example in which not more than one is satisfied, and the drill life is short. Nos. 6, 11, and 12 are comparative examples when the amount of Co in the A portion and the shank portion is too small, and No. 7 is a comparative example when the amount of Cr ₃ C ₂ and VC in the A portion and the shank portion are too large. . 8 is a comparative example when the average particle size of WC is too large. No. 9 is a comparative example when the amount of Co in part B is too large, and No. 10 is a comparative example when the average particle size of part B is too large.

[0027]

Since the present invention is constructed as described above, abrasion resistance, chipping resistance, and breakage resistance are simultaneously increased, and a long tool life and excellent reliability for shaft cutting materials are provided. It can be done.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuo Abe Referee, 538 Hiraoka-cho Tsuchiyama, Akashi City Referee Masatoshi Koike Referee Tomoya Kato Referee Akihide Mihara (56) References JP-A-64-52043 (JP, A) JP-A-62-63005 (JP, A) JP-A-2-221353 (JP, A)

Claims (2)

(57) [Claims] 1. A shaft cutting tool material having a cutting edge having a length L, a radius r, and a shank portion, wherein the material is 0.1 L to 1.0 L from the cutting edge and 0% from the axis of the cutting edge. .
When the range of 1 to 0.4r is A part and the outer periphery of the A part is B part, each composition of the A part, the shank part, and the B part is determined in the following range. Material for shaft cutting tools. [Part A and shank part] Co: 7 to 30% (meaning by weight, hereinafter the same,
May be replaced by Ni) Cr ₃ C ₂ : 12% or less of Co (however, excluding 0%, and when 50% or less of Co is replaced by Ni,
+ Ni) VC: 5% or less of Co (excluding 0%, and Co
Co + N when 50% or less of
i) Remainder: WC having an average particle size of 0.8 μm or less and unavoidable impurities [Part B] Co: 5 to 15% (however, up to 50% of Co may be replaced with Ni, and the amount of Co in Part A is based on even more than 4% less <br/> physician) TiC, TaC and (Ta, Nb) 1 or more kinds selected from the group consisting of _{C: 0.1~ 20% Cr 3 C} 2: 12% of Co The following (including 0%, C
When 50% or less of o is replaced by Ni, Co + N
i) VC: 5% or less of Co (including 0%, and 5% of Co
Co + Ni when 0% or less is replaced by Ni) The balance: WC having an average particle size of 3 μm or less (however, the WC of part A above)
Average particle size larger than) and unavoidable impurities 2. The material for a shaft cutting tool according to claim 1, wherein the composition of the A portion and the shank portion is TaC, Mo _2.
One or more selected from the group consisting of C, ZrC and HfC are added in an amount of less than 2% and / or the composition of part B is selected from the group consisting of Mo ₂ C, ZrC and HfC. A material for a shaft cutting tool comprising one or more kinds.