JPH11236671A - Throw away cutting tip made of surface-coated cemented carbide excellent in chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tip made of surface-coated cemented carbide excellent in chipping resistance. SOLUTION: In a cutting tip made of surface-coated cemented carbide obtd. by vapor-depositing hard coating layers on the surface of a super hard substrate, the layer structure is composed in such a manner that, as the hard coating layers, over the cutting edge ridgeline part in which the face and flank of the cutting edge part cross in the super hard substrate, in order from the surface of the super hard substrate, (a) a TiN layer having 0.1 to 2 μm average layer thickness and (b) a 1-TiCN layer having 1 to 15 μm average layer thickness are formed, and moreover, on the face and flank, (c) a TiCO layer and/or a TiCNO layer having 0.1 to 2 μm average layer thickness, (d) an α-Al2 O3 layer and/or a κ-Al2 O3 layer having 0.5 to 15 μm average layer thickness and (e) a TiN layer having 0.1 to 3 μm average layer thickness are formed, the exposed face of the 1-TiCN layer is present at a width of 2 to 30 μm along the cutting edge ridgeline part, and further the average layer thickness of the whole body of the hard coating layers in the face and flank is regulated to 3 to 30 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is applicable to the case where intermittent cutting of difficult-to-cut materials such as stainless steel and heat-resistant alloys such as Inconel and Hastelloy is performed under heavy cutting conditions such as high feed and high cutting. The present invention relates to a surface-coated cemented carbide throw-away cutting tip (hereinafter referred to as a coated cemented carbide tip) that exhibits excellent fracture resistance.

[0002]

2. Description of the Related Art Conventionally, generally, as shown in FIG. 2 in which a cutting edge portion is illustrated in a schematic longitudinal sectional view of a main part, a surface of a tungsten carbide-based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate) is granular. A titanium carbide (hereinafter, referred to as TiC) layer, a titanium nitride (hereinafter, also referred to as TiN) layer having a crystal structure,
Titanium carbonitride (hereinafter referred to as TiCN) layer, titanium carbonate (hereinafter referred to as TiCO) layer, titanium oxynitride (hereinafter referred to as TiCO)
TiNO) layer and titanium carbonitride (hereinafter referred to as T
a Ti compound layer composed of one or more of iCNO layers, an α-type aluminum oxide (hereinafter referred to as α-Al ₂ O ₃ ) layer and / or a κ-type layer also having a granular crystal structure. There is known a coated cemented carbide tip obtained by chemical vapor deposition and / or physical vapor deposition of a hard coating layer composed of an Al ₂ O ₃ layer with an average layer thickness of ₃ to 30 μm. For example, it is also known that it is used for continuous cutting or interrupted cutting of steel, cast iron, or the like. Further, for example, Japanese Patent Application Laid-Open Nos. Hei 3-87369 and Hei 6
As described in JP-A-8008, etc., in the hard coating layer of the coated superhard tip, the TiC formed at a high temperature of 1000 ° C. or more using a normal chemical vapor deposition apparatus.
TiC having a vertically-growing crystal structure formed by performing chemical vapor deposition at a medium temperature range of 700 to 950 ° C. using a mixed gas containing an organic carbonitride as a reaction gas.
By replacing the N layer to improve the toughness of the hard coating layer,
There is also known a coated carbide tip in which the occurrence of chipping or chipping (small chipping) of the cutting blade is significantly suppressed.

[0003]

On the other hand, in recent years, high performance and high output of cutting machines have been remarkable, and there has been a strong demand for labor saving. Accordingly, cutting has been performed at high speed and high feed and high cutting depth. Tend to be heavy cutting,
In the above-mentioned conventional coated carbide tips, this is used for cutting, for example, stainless steel, and intermittent cutting of difficult-to-cut materials such as heat-resistant alloys such as Inconel and Hastelloy under heavy cutting conditions such as high feed and high cutting. And, although the Al ₂ O ₃ layer constituting the hard coating layer has excellent wear resistance and heat resistance, since it is highly brittle, it is easy for chips such as chipping or chipping to occur in the cutting edge portion, Due to this, the service life is currently reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoints, as a result of researching to develop a coated cemented carbide chip having excellent fracture resistance, the structure of the hard coating layer of the coated cemented carbide chip was changed in the order of (a) granular A TiN layer having a crystal structure (hereinafter simply referred to as a TiN layer), (b) a TiCN layer having a vertically elongated crystal structure (hereinafter referred to as an l-TiCN layer), (c) a TiCO layer having a granular crystal structure and / or Or a TiCNO layer (hereinafter simply referred to as a TiCO layer and a TiCNO layer), (d) an α-Al ₂ O ₃ layer having a granular crystal structure and / or a κ-
Al ₂ O ₃ layer (hereinafter simply referred to as α-Al ₂ O ₃ layer and κ-
Al ₂ O ₃ layer), (e) T having a granular crystal structure
After specifying the iN layer (hereinafter simply referred to as a TiN layer), the rake face, flank face, and the cutting edge ridge line where the rake face and the flank intersect with each other are provided as follows: ) Average layer thickness: 0.1 to 2 µm TiN layer, (b) Average layer thickness: 1 to 15 µm l-TiCN layer, and (c) average layer thickness on the rake face and flank face : 0.1 to 2 μm TiCO layer and / or
Or a TiCNO layer; (d) an α-Al ₂ O ₃ layer and / or a κ-Al ₂ O ₃ layer having an average layer thickness of 0.5 to 15 μm; and (e) a TiN layer having an average layer thickness of 0.1 to ₃ μm. Therefore, as shown in FIG. 1, the cutting edge portion is shown in a schematic longitudinal sectional view of a main part, and the above-mentioned TiCO
Layer and / or a TiCNO layer, an α-Al ₂ O ₃ layer and / or a κ-Al ₂ O ₃ layer, and a TiN layer, and the width of 2 to 30 μm along the cutting edge line.
-The exposed surface of the TiCN layer is present, and the total average layer thickness of the hard coating layer on the rake face and flank face is 3 to 30 μm
With a layered structure, even when intermittent cutting of difficult-to-cut materials such as stainless steel or heat-resistant alloys is performed under heavy cutting conditions such as high feed and high depth of cut, direct contact with the work material causes severe cutting impact. What is received is a highly tough l-TiCN layer exposed over a predetermined width at the cutting edge ridge, and since the brittle Al ₂ O ₃ layer does not exist at the cutting edge ridge, chipping or chipping of the cutting edge may occur. The occurrence of deficiency is significantly suppressed,
The research results show that excellent cutting performance is exhibited over a long period of time.

The present invention has been made on the basis of the above-mentioned research results, and is directed to a coated superhard chip formed by chemical vapor deposition and / or physical vapor deposition of a hard coating layer on the surface of a superhard substrate. As a layer, over the rake face, flank face, and cutting edge ridge line where the rake face and the flank face intersect with each other, in order from the cemented carbide substrate surface side in the cemented carbide substrate, (a) average layer thickness: Forming a TiN layer of 0.1 to 2 μm, (b) an average layer thickness: 1-TiCN layer of 1 to 15 μm, and further, on the rake face and flank face, (c) average layer thickness: 0.1 to 2 μm TiCO layer and / or
Or a TiCNO layer; (d) an α-Al ₂ O ₃ layer and / or a κ-Al ₂ O ₃ layer having an average layer thickness of 0.5 to 15 μm; and (e) a TiN layer having an average layer thickness of 0.1 to ₃ μm. , And therefore, the above-mentioned Ti
The CO layer and / or the TiCNO layer, the α-Al ₂ O ₃ layer and / or the κ-Al ₂ O ₃ layer, and the TiN layer do not exist, and the width of 2 to 30 μm is set along the cutting edge ridge. An exposed surface of the TiCN layer is present, and the total average layer thickness of the hard coating layer on the rake face and flank face is 3 to 30 μm.
This is characterized by a coated carbide tip having a layer structure of m and excellent in fracture resistance.

Next, the reason why the average layer thickness and the overall average layer thickness of the constituent layers of the hard coating layer of the coated superhard tip of the present invention are limited as described above will be described. (A) TiN layer The TiN layer has excellent adhesion to the surface of the superhard substrate, and prevents diffusion and migration of the constituents of the superhard substrate into the hard coating layer, thereby suppressing a decrease in wear resistance of the hard coating layer. However, if the layer thickness is less than 0.1 μm, the above-mentioned effect is not sufficiently exhibited. On the other hand, the above-mentioned effect is sufficient with a layer thickness of up to 2 μm. I decided.

(B) l-TiCN layer The l-TiCN layer has excellent toughness, and particularly heavy cutting such as high feed and high cutting in intermittent cutting of stainless steel or heat-resistant alloy, etc., which requires high toughness. Even when the cutting is performed under the conditions, the cutting edge is exposed over a predetermined width and has an action of suppressing the occurrence of chipping and chipping or other defects in the cutting edge. When the layer thickness exceeds 15 μm, thermoplastic deformation tends to occur on the cutting edge, which causes uneven wear. Therefore, the layer thickness is set to 1 to 15 μm. . Therefore, when the exposed surface width of the l-TiCN layer is less than 2 μm,
When the excellent toughness of the TiCN layer cannot be sufficiently exhibited, when the width of the exposed surface exceeds 30 μm, uneven wear tends to occur on the ridge of the cutting edge, which causes a shortened service life. Therefore, the exposed surface width is 2 to 30 μm
It was decided.

(C) TiCO layer and TiCNO layer Generally, for example, an l-TiCN layer and an α-Al_Two O_Three Layer density
Adhesion is relatively low, and when both are directly laminated,
Although it causes the hard coating layer to peel off, the TiCO layer and Ti
Each of the CNO layers includes an l-TiCN layer, a TiC layer,
Α-Al_Two O _Three Layer and κ-Al_Two O_Three With any of the layers
Firmly adheres to each other, and thus the adhesion between the constituent layers of the hard coating layer
It has the effect of contributing to improvement, but its thickness is less than 0.1 μm.
If it is not enough, the desired effect of improving adhesion cannot be obtained, while the
Exceeds 2μm, chipping or chipping occurs at the cutting edge
The thickness of the layer is set to 0.1 to 2 μm
Was.

(D) α-Al ₂ O ₃ layer and κ-Al ₂
O ₃ layer The α-Al ₂ O ₃ layer and the κ-Al ₂ O ₃ layer are both excellent in oxidation resistance and thermal stability and have high hardness. However, if the layer thickness is less than 0.5 μm, the desired effect of improving wear resistance cannot be obtained, while if the layer thickness exceeds 15 μm, chipping or chipping of the cutting edge may occur. The layer thickness is determined to be 0.5 to 15 μm because it is likely to occur.

(E) TiN layer Since the TiN layer itself has a golden color tone, it is formed to facilitate discrimination between before and after use of the cutting tip. When the layer thickness is less than 1 μm, the application of the color tone is insufficient. On the other hand, when the layer thickness is up to 3 μm, the layer thickness is set to 0.1 to 3 μm.

(F) Overall Average Thickness of Hard Coating Layer If the thickness is 3 μm, the desired excellent wear resistance cannot be ensured. On the other hand, if the thickness exceeds 30 μm,
Since chipping and chipping easily occur in the cutting blade, the overall average layer thickness was determined to be 3 to 30 μm.

[0012]

Next, the coated cemented carbide tip of the present invention will be specifically described with reference to examples. As raw material powder,
Average particle size: fine WC powder having 1.5 μm, same as 3 μm
Medium WC powder, 1.2 μm (Ti, W) CN (weight ratio, same hereafter, TiC / TiN / WC = 24/20)
/ 56) Powder, ZrCN (ZrC / Zr) of 1.2 μm
N = 70/30) powder, 1.3 μm (Ta, Nb)
C (TaC / NbC = 90/10) powder, 1 μm C
r powder and Co powder of 1.2 μm were prepared, and these raw material powders were blended in the composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and then formed into a green compact of a predetermined shape. Press molding and vacuum sintering of this green compact under the conditions shown in Table 1 also provide ISO · CNMG1
Carbide substrates A to E having a shape conforming to No. 60612 were produced. Furthermore, 100 To
After holding for 1 hour at a temperature of 1400 ° C. in an atmosphere of rr CH ₄ gas, a slow cooling carburizing treatment is performed, and after the treatment, carbon and Co adhering to the surface of the carbide substrate are removed by acid and barrel polishing. A Co-rich zone having a maximum Co content of 17.5% by weight and a depth of 39 μm was formed on the surface of the substrate at a position 11 μm from the surface. In addition, the sintered body C had a maximum Co content of 11.2% by weight and a depth of 28 μm at a position 20 μm from the surface of the super-hard substrate C as sintered.
In the Co-enriched zone of m and the carbide substrate D, a Co-enriched zone having a maximum Co content of 9.7% by weight and a depth of 25 μm is formed on the surface portion at a position of 18 μm from the surface. The remaining cemented carbide substrates A and B did not have the Co-enriched zone and had an overall homogeneous structure. Table 1 shows the internal hardness (Rockwell hardness A scale) of each of the carbide substrates A to E.

Next, in a state where the surfaces of these superhard substrates A to E have been subjected to honing processing, a conventional chemical vapor deposition apparatus is used, and Table 2 (indicated by * in the table, TiCN is JP-A-6-80).
No. 10 has a vertically-grown crystal structure), and a hard coating layer having a layer configuration and an average layer thickness shown in Table 3 is uniformly formed in each thickness. Thus, comparative coated carbide tips 1 to 10 were produced.

Then, along the respective cutting edge ridges of the comparative coated carbide tips 1 to 10 obtained as described above, using a grindstone having various curved surfaces, a TiCO layer and / or a TiCNO layer, α An Al ₂ O ₃ layer and / or κ
The Al ₂ O ₃ layer and the TiN layer were removed by polishing, and the exposed surface of the 1-TiCN layer was formed along the cutting edge ridge over the width shown in Table 4 and shown in FIG. The coated superhard chips 1 to 10 of the present invention were manufactured by using a layer structure as shown.

Next, the coated carbide tips 1 to 1 according to the present invention will be described.
0 and comparative coated carbide tips 1 to 10 Work material: stainless steel (SUS304) with four longitudinal grooves at regular intervals in the longitudinal direction, cutting speed: 200 m / min. Infeed: 5 mm Feed: 0.35 mm / rev. Cutting time: 10 minutes A wet high-cut intermittent cutting test of stainless steel was performed under the following conditions, and the flank wear width of the cutting edge was measured. Table 4 shows the results of these measurements.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

From the results shown in Table 4, all of the coated carbide tips 1 to 10 of the present invention in which the hard coating layer has an exposed surface of the l-TiCN layer having a predetermined width along the cutting edge ridge line, are all present. Since the l-TiCN layer having high toughness directly abuts the stainless steel as a work material directly from the start of cutting and sufficiently absorbs a severe cutting impact, the cutting edge portion is excellent without chipping or chipping. In comparison coated carbide tips 1-10, where the layer configuration and average layer thickness of the hard coating layer are the same over the rake face, flank face, and cutting edge ridge portion, while exhibiting cutting performance, In any case, it is apparent that chipping or chipping occurs in the cutting edge ridge portion due to a high cutting impact particularly applied to the Al ₂ O ₃ layer at the cutting edge ridge portion, which leads to a short service life in a relatively short time. . As described above, the coated cemented carbide tip of the present invention is not limited to continuous cutting and interrupted cutting under ordinary conditions such as general steel and cast iron, and heat-resistant alloys such as stainless steel and inconel, which are difficult-to-cut materials. In particular, even when performing these cuttings under heavy cutting conditions such as high feed and high cutting, intermittent cutting with extremely high impact, it shows excellent fracture resistance and excellent wear resistance over a long period of time. To demonstrate.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a main part of a cutting blade portion of a coated carbide tip according to the present invention.

FIG. 2 is a schematic longitudinal sectional view of a main part of a cutting blade portion of a conventional coated carbide tip.

Claims (1)

[Claims] 1. A cutting tool made of a surface-coated cemented carbide obtained by chemical vapor deposition and / or physical vapor deposition of a hard coating layer on the surface of a tungsten carbide-based cemented carbide substrate. Over the rake face, flank face, and cutting edge ridge line where the rake face and the flank face intersect, the base cemented carbide substrate has, in order from the substrate surface side: (a) average layer thickness: 0.1 to A titanium nitride layer having a granular crystal structure of 2 μm, (b) a titanium carbonitride layer having an average layer thickness of 1 to 15 μm and a vertically-grown crystal structure are formed, and the rake face and the flank include (c) Average layer thickness: titanium carbonate layer and / or titanium carbonitride layer having a granular crystal structure of 0.1 to 2 μm, (d) average layer thickness: α type having a granular crystal structure of 0.5 to 15 μm and / or Or a κ-type aluminum oxide layer, (e) an average layer thickness: a titanium nitride layer having a granular crystal structure of 0.1 to 3 μm is formed, and the above-mentioned titanium carbonate layer and / or Titanium oxynitride layer,
No α-type and / or κ-type aluminum oxide layer and no titanium nitride layer are present, and 2-3 along the cutting edge ridge.
A surface having excellent fracture resistance, wherein the exposed surface of the titanium carbonitride layer has a width of 0 μm, and the total average layer thickness of the hard coating layer on the rake face and the flank is 3 to 30 μm. Throwaway cutting insert made of coated cemented carbide.