JPH05179310A - Wear resistant cemented carbide end mill - Google Patents

Abstract

PURPOSE:To inhibit the chipping and wear of the edge of the cutting blade of a WC-based cemented carbide end mill and to prolong the cutting life by forming a specified wear resistant coating film of AlTiNC on the surface of the cutting blade of the specified substrate of the end mill. CONSTITUTION:This cemented carbide end mill has a wear resistant coating film of 0.05-5mum thickness formed on the surface of the cutting blade of the substrate. The coating film has a chemical compsn. represented by a formula (AlxTi1-x)(NyC1-y) (where 0.56<=x<=0.75 and 0.6<=y<=1). The substrate is based on WC of <=0.7mum average grain size, contains 8-16wt.% Co as a binder and further contains VC satisfying 0.01-0.09 ratio of VC to Co.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbide end mill having excellent wear resistance, and in particular, a TiAlNC wear resistant coating is formed on the cutting blade surface of a WC-based carbide end mill base material having a specified composition. The present invention relates to a wear-resistant cemented carbide end mill which is formed to suppress the amount of wear and suppresses damage such as chipping and enables a long life.

[0002]

2. Description of the Related Art When manufacturing high speed tool steel, cemented carbide tool steel, etc., in order to obtain better performance such as wear resistance, the surface of the tool base material is made of nitride such as Ti It has been performed to form a wear resistant film made of
For example, cutting tools such as chips and drills have been put to practical use in which a heat-resistant hard coating such as TiAlN, TiAlC, or TiAlNC is formed on the surface thereof.

Among these, the hard coating disclosed in Japanese Patent Application Laid-Open No. 2-194159 filed by the present applicant is (Al _x
Ti _1-x ) (N _y C _1-y ) [where 0.56 ≦ x ≦ 0.
75, 0.6 ≦ y ≦ 1], having excellent heat resistance and oxidation resistance to withstand high cutting heat, and being hard and extremely excellent in wear resistance Therefore, there are great expectations as a means for improving the wear resistance of chips and drills.

[0004]

SUMMARY OF THE INVENTION Based on the above findings, the present inventors have conducted research to utilize the technology for improving wear resistance disclosed in the invention of the prior application to improve the wear resistance of a cemented carbide end mill. I advanced. As a result, in end mills that mainly perform interrupted cutting and place importance on finish cutting, microchipping of the cutting edge due to interrupted cutting is more likely to occur than in chips and drills, and the above-described high-performance wear-resistant coating on the end mill surface. Even if formed, the excellent coating performance cannot be effectively reflected in improving the performance of the end mill (improving wear resistance and prolonging life).

The present invention has been made in view of the above circumstances, and its purpose is to effectively utilize the characteristics of the wear resistant coating disclosed in the above-mentioned prior invention to improve the performance of the end mill. An object of the present invention is to provide a cemented carbide end mill that does not cause microchipping of the cutting edge and has excellent wear resistance.

[0006]

The structure of the wear-resistant cemented carbide end mill according to the present invention, which has been able to solve the above-mentioned problems, has a structure (Al
_x Ti _1-x ) (N _y C _1-y ) [where 0.56 ≦ x ≦
0.75, 0.6 ≦ y ≦ 1] with a chemical composition of 0.05 μm or more and less than 5.0 μm in thickness. Contains WC having an average particle size of 0.7 μm or less as a main component, contains 8 to 16% by weight of Co as a binder, and contains VC so that 0.01 <VC / Co <0.09. However, it has a gist.

[0007]

In the present invention, the chemical composition of the wear-resistant coating is (Al _x Ti _1-x ) (N _y C _1-y ), where 0.5
6 ≦ x ≦ 0.75, 0.6 ≦ y ≦ 1] is assumed to be used. The reason for defining the chemical composition of the coating in this way is as clarified in JP-A-2-194159. When x is less than 0.56, the oxidation resistance of the coating is insufficient, and the cutting edge portion becomes In cemented carbide end mills that often reach high temperatures of over 800 ° C, the heat of cutting causes oxidative deterioration of the coating, and satisfactory wear resistance cannot be obtained. When x exceeds 0.75, the coating becomes excessive. This is because it becomes hard and the flank wear becomes remarkable. The value of y also has a deep relationship with the oxidation resistance and wear resistance of the film. If y is less than 0.6, the oxidation resistance at high temperatures will be extremely poor and the wear resistance will also decrease. Since the wear resistance of the coating improves as y approaches 1, the value of y is 0.6.
If it is above, the one closer to 1 is preferable, and a film in which y is 1, that is, (Al _x Ti _1-x ) N is recommended as one of the most preferable films.

The method for forming the above coating on the surface of the cutting blade of the end mill substrate is not particularly limited, but the most preferable is the arc discharge ion plating method using a cathode as an evaporation source.

By the way, in order to effectively exhibit the characteristics of the (Al _x Ti _1-x ) (N _y C _1-y ) coating excellent in the above-mentioned oxidation resistance and abrasion resistance, the constitution of the end mill substrate is used. And the film thickness of the film are extremely important. First, as the end mill base material, WC having an average particle size of 0.7 μm or less is contained as a main component, and Co as a binder is contained in an amount of 8 to 16% by weight. A film containing VC in an amount of 01 <VC / Co <0.09 is used, and the thickness of the film is 0.0
It must be more than 5 μm and less than 5.0 μm.

The constitution of the end mill base material is defined as above in order to impart toughness to the base material itself to withstand intermittent cutting and solve the problem of microchipping, thereby effectively exhibiting the characteristics of the above coating. When the crystal grain size of WC, which is the main constituent material, exceeds 0.7 μm, chipping due to microchipping is likely to occur in the cutting edge portion in the cutting process, resulting in excellent wear resistance as intended in the present invention. You will not be able to get sex. In addition, Co contained as a binder
Content of WC is such that fine WC particles are strongly bonded to each other.
It is extremely important to prevent chipping and breakage due to falling of grains, and it must be contained in an amount of at least 8% by weight or more in order to secure a sufficient binding force. However, if the amount of Co is too large, the material is likely to be plastically deformed, and the cutting edge tends to be damaged with a relatively small amount of cutting, so it is necessary to suppress the content to 16% by weight or less. The more preferable content of Co is in the range of 12 to 14% by weight.

Next, VC is an essential component for exerting its excellent toughness by maintaining the above-mentioned WC particles finely and uniformly and making the entire substrate a uniform structure,
The content is selected from the range satisfying the requirement of 0.01 <VC / Co <0.09 based on the amount of Co contained as a binder. If the content is out of this range, the structure becomes uneven in any case. Therefore, the performance intended by the present invention cannot be obtained. A more preferable ratio of VC / Co is 0.
It is in the range of 03 to 0.07.

The essential components of the end mill base material in the present invention are as described above, and Cr _{3 is} another component.
The inclusion of a small amount of carbide selected from the group consisting of C ₂ , HfC, NbC and TaC is effective in further increasing the toughness and heat resistance of the material itself. However, if the content of these carbides becomes too large, the toughness of the base material deteriorates and causes chipping. Therefore, even if added, the content must be kept to 2% by weight or less in the total ratio. ..

The method for producing the end mill base material having the above requirements is not particularly limited, but the most general method is as follows:
For example, the raw material powder is blended to have the above component composition,
After mixing in an attritor in an organic solvent, drying and granulating, the resulting granulated powder is compacted and then dewaxed and semi-baked, and then semi-baked to make it into an end-mill shaped material. And then sintering in a vacuum atmosphere,
Finally, a method of performing HIP processing for eliminating internal defects is exemplified.

A WC-based end mill substrate satisfying the above requirements
The (Al that is formed on the surface of the cutting blade _x Ti_1-x ) (N_y 
C_1-y ) The thickness of the film is more than 0.05 μm and less than 5.0 μm
Must be set in the range of, and the film thickness is insufficient.
In this case, the effect of extending the cutting life by forming a hard film is sufficiently
If it is not volatilized and is too thick, film peeling occurs in the cutting process.
It becomes easy and the purpose of forming a hard film cannot be fulfilled. Hard leather
It is more preferable to secure both cutting life and peel resistance of the film.
The thickness of the above-mentioned coating is in the range of 1.0 to 4.0 μm.
It

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0016]

【Example】

Example 1 WC-based carbide end mill material (average particle size of WC: 0.5 μ)
m, Co content: 12% by weight, VC content: 0.3% by weight)
A cutting test was carried out on the surface of the cutting blade having the AlTiNC wear-resistant film having the film thickness shown in Table 1 under the following conditions, and the state of wear of the cutting blade and the occurrence of chipping at the cutting edge were examined.

However, the method of forming the abrasion resistant film was as follows. That is, the end mill base material is attached to the substrate holder of the cathode arc type ion plating apparatus using Al _0.6 Ti _0.4 as the cathode electrode. In this device, a substrate rotating mechanism and a heater were installed to ensure the uniformity of the film formation state.

In forming the film, the substrate temperature is kept at 400 ° C. by a heater, a bias voltage of −70 V is applied to the substrate, and a high-purity N ₂ gas is supplied to the inside of the apparatus.
By introducing up to × 10 ^-3 Torr and performing arc discharge, the discharge time was adjusted to obtain a predetermined film thickness. The film composition was determined by Auger spectroscopy (Al _0.62 T
i _0.38 ) N, and the film thickness was confirmed by a scanning electron microscope of the film cross section. <Cutting conditions> Cutting blade: 2 blades, diameter 10 mm Work material: SKD11 (HB206) Cutting speed: 60 m / min Feed speed: 0.044 mm / tooth Depth of cut: Rd1 mm x Ad15 mm Cutting method: Down cut Cutting oil: Dry cutting Length: 6m

The results are also shown in Table 1. In the bare material on which no coating is formed, the cutting edge is chipped at a short cutting length, and the chipping is mainly caused when the film thickness is 0.5 μm or less. Abrasion is remarkable, and when the film thickness is 5.0 μm or more, peeling of the abrasion resistant film is observed. On the other hand, in the case where the film thickness is adjusted to more than 0.5 μm and less than 5.0 μm, chipping of the cutting edge portion and film peeling are not recognized, and the amount of wear is very small.

[0020]

[Table 1]

Example 2 A WC-based cemented carbide end mill substrate having a Co content of 12% by weight, a VC content of 0.4% by weight, and a WC average particle size of 0.5 μm, 0.7 μm or 1.0 μm. Using a certain material, a wear resistant coating of (Al _0.62 Ti _0.38 ) N of about 2.5 μm was formed on the surface of the cutting edge of the base material in the same manner as in Example 1, and the cutting test was conducted under the following conditions. I did. <Cutting conditions> Cutting blade: 2 blades, diameter 10 mm Work material: SKD61 (HRC45) Cutting speed: 80 m / min Feed rate: 0.044 mm / tooth Depth of cut: Rd1 mm x Ad15 mm Cutting method: Down cut Cutting oil: Dry cutting Length: 6m

The results are shown in Table 2. When the WC average particle size of the end mill base material exceeds 0.7 μm, chipping occurs at the cutting edge with a short cutting length, whereas the WC average particle size is 0. It can be seen that with a microstructure having a fineness of 0.7 μm or less, no chipping was observed at the cutting edge even after cutting 6 m, and the amount of wear was small.

[0023]

[Table 2]

Example 3 An end mill base material having a WC average particle diameter of 0.5 μm and various Co and VC contents was used. According to Al _0.60
A wear resistant coating of Ti _0.40 N _0.8 C _0.2 was formed. In the film formation, Al _0.60 Ti _0.40 was used as the cathode electrode.
Was used, and the same conditions as in Example 1 were adopted, except that N ₂ / CH ₄ mixed gas was used as the introduction gas to the ion plating apparatus. A cutting test was performed on each of the obtained film forming materials under the following conditions, and the results shown in Table 3 were obtained. <Cutting conditions> Cutting blade: 2 blades, diameter 10 mm Work material: SKD61 (HRC45) Cutting speed: 80 m / min Feed rate: 0.044 mm / tooth Depth of cut: Rd1 mm x Ad15 mm Cutting method: Down cut Cutting oil: Dry cutting Length: 6m

[0025]

[Table 3]

In Table 3, No. 1 has a lack of Co content, so a chip is generated in a very small amount of cutting due to a lack of binding force.
In addition, since No. 9 has an excessively high Co content, chipping due to softening of the material is observed. Further, in Nos. 4, 6 and 10, the VC content was out of the specified range of the present invention, and all of them had chipping of the cutting edge. For these, No. 2, 3,
Nos. 5, 7, 8, 11, and 12 are examples satisfying the prescribed requirements of the present invention, in which the cutting edge does not chip and the amount of wear is small.

[0027]

The present invention is constituted as described above, and the AlTiNC system having the chemical composition and the thickness specified on the cutting blade surface of the WC type cemented carbide end mill base material having the specified component composition and the WC particle size is specified. By forming an oxidation resistant and wear resistant film of, it is possible to obtain a carbide end mill that has excellent wear resistance without causing edge damage due to microchipping, etc., and has an extremely excellent cutting life. For example, H _RC
It has become possible to provide a high-performance end mill that can sufficiently withstand high-speed cutting of a high hardness work material of 40 or more.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Takeo Komine 3-34-27 Yamate, Kakogawa-shi (72) Inventor Yusuke Tanaka 7-16-4-104 Nishimaiko, Tarumi-ku, Kobe (72) Inventor Koichiro Wakihira Kobe 4-13-8 Gakugaoka, Tarumi-ku, Yokohama

Claims (1)

[Claims] 1. A surface of a cutting blade in a WC-based carbide end mill is made of (Al _x Ti _1-x ) (N _y C _1-y ) [however, 0.5
6 ≦ x ≦ 0.75, 0.6 ≦ y ≦ 1] in a wear-resistant cemented carbide end mill formed by forming a wear-resistant film having a chemical composition of 0.05 μm or more and less than 5.0 μm, The end mill base material contains WC having an average particle size of 0.7 μm or less as a main component, contains 8 to 16% by weight of Co as a binder, and has 0.01 <VC / Co <0.09. A wear-resistant cemented carbide end mill characterized by containing VC.