JP3358533B2 - Slow-away cutting insert made of surface-coated cemented carbide with excellent fracture resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a surface-coated cemented carbide throwing material which exhibits excellent fracture resistance even when intermittent cutting of various steels is performed under heavy cutting conditions such as high feed and high cutting. The present invention relates to a way cutting tip (hereinafter referred to as a coated carbide tip).

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 7-328809.
(A) nitriding of a granular crystal structure having an average layer thickness of 0.1 to 2 μm as a lowermost layer on the surface of a tungsten carbide-based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate). Titanium (hereinafter, referred to as TiN) layer; (b) Titanium carbonitride (hereinafter, referred to as 1-TiCN) having a vertically elongated crystal structure having an average layer thickness of 3 to 15 μm as a lower layer
A layer, (c) an intermediate layer having an average layer thickness of 0.5 to 5 μm, each of which has a granular crystal structure, a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, a nitroxide layer, And a carbonitride layer (hereinafter, TiC layer, TiN layer, T
iCN layer, TiCO layer, TiNO layer, and TiCNO
), And (d) as an upper layer, an α-type and / or κ-type aluminum oxide layer (hereinafter referred to as α-type) having a granular crystal structure having an average layer thickness of 0.5 to 10 μm. An Al ₂ O ₃ layer and a κ-Al ₂ O ₃ layer), (e) a titanium nitride (hereinafter referred to as TiN) layer having a granular crystal structure having an average layer thickness of 0.1 to 2 μm as a surface layer; There is known a coated superhard tip formed by subjecting the hard coating layer constituted by the above (a) to (e) to chemical vapor deposition and / or physical vapor deposition with a total average layer thickness of 5 to 20 μm. It is also well known that the coated cemented carbide tip is used for continuous cutting or intermittent cutting of various steels, for example. Further, the 1-TiCN layer constituting the hard coating layer of the coated superhard tip is disclosed in, for example, JP-A-3-87369.
And Japanese Patent Application Laid-Open No. 6-8008, 700 to 950 using a general chemical vapor deposition apparatus and a mixed gas containing an organic carbonitride as a reaction gas.
It is also known to be formed by performing chemical vapor deposition in a medium temperature range of ° C.

[0003]

On the other hand, in recent years, there has been a strong demand for labor saving and energy saving in the cutting work, and accordingly, in the cutting work, not only the cutting speed has been increased, but also the high feed and the high cutting depth. There is a tendency to be cut under heavy cutting conditions such as, but in the above-mentioned conventional coated carbide tip, because the l-TiCN layer constituting the hard coating layer does not have sufficient toughness, In particular, for example, when intermittent cutting of various steels is performed under heavy cutting conditions such as high feed and high cutting, chips such as chipping and chipping (small chipping) are likely to occur in the cutting edge portion, which causes a relatively short time. At present, the service life is reached.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoint, focusing on the above-mentioned conventionally coated carbide tip, as a result of conducting research to improve the toughness of the l-TiCN layer constituting the hard coating layer, when forming the l-TiCN layer, In the middle of the layer thickness direction, the l-Ti
Titanium oxycarbonitride (hereinafter referred to as TiC) having a vertically grown crystal structure as an extension of the vertically grown crystal structure formed in the CN layer
NO) (shown as NO) is provided at one or more places, has an alternately stacked structure with a TiCNO band phase starting from the TiCN band phase and ending with the TiCN band phase along the layer thickness direction, and is vertically elongated continuously over the entire band phase. When a two-phase stacked layer having a grown crystal structure is formed and this two-phase stacked layer is applied as a lower layer of the hard coating layer of the coated cemented carbide chip, the two-phase stacked layer replaces the hard coating layer of the conventionally coated cemented carbide chip. Since it has much higher toughness than the constituting l-TiCN layer, the coated coated carbide tip of this result can be used, for example, for interrupted cutting of various steels under heavy cutting conditions such as high feed and high cutting. The research results show that even when the cutting is performed, the cutting edge portion will exhibit excellent cutting performance for a long period of time without occurrence of chipping or chipping.

The present invention has been made on the basis of the above research results, and comprises: (a) a TiN layer having an average layer thickness of 0.1 to 2 μm as a lowermost layer,
(B) The lower layer has an average layer thickness of 3 to 15 μm, has an alternately stacked structure with a TiCNO band phase starting from a TiCN band phase and ending with a TiCN band phase along the layer thickness direction, and these band phases as a whole. (C) As an intermediate layer, a TiC layer and a TiN layer having an average layer thickness of 0.5 to 5 μm.
Layer, TiCN layer, TiCO layer, TiNO layer, and Ti
One or more of the CNO layers, (d) as the upper layer, α-Al ₂ O having an average layer thickness of 0.5 to 10 μm
₃ layers and / or κ-Al ₂ O ₃ layers, (e) a TiN layer having an average layer thickness of 0.1 to 2 μm as a surface layer, and a hard coating layer composed of the above (a) to (e) 5-20μ
It is characterized by a coated chip having excellent fracture resistance, which is formed by chemical vapor deposition and / or physical vapor deposition with a total average layer thickness of m.

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) Lowermost layer (TiN layer) The TiN layer has excellent adhesion to the surface of the superhard substrate, and prevents diffusion and migration of the components of the superhard substrate into the hard coating layer. It has an effect of suppressing the deterioration of the property, but if the layer thickness is less than 0.1 μm, the above effect is not sufficiently exerted. On the other hand, the above effect is sufficient with a layer thickness of up to 2 μm. It was determined to be 1-2 μm.

(B) Lower Layer (Two-Phase Stacked Layer) The two-phase stacked layer exhibits higher toughness as compared with the l-TiCN layer, and particularly provides a high feed rate for interrupted cutting of various steels that require high toughness. Even when performed under heavy cutting conditions such as high cutting depth, there is an effect of suppressing the occurrence of chipping and other defects in the cutting edge portion, but when the layer thickness is less than 3 μm, the above effect is sufficiently suppressed. On the other hand, when the layer thickness exceeds 15 μm, thermoplastic deformation is likely to occur in the cutting edge portion, which causes uneven wear. Therefore, the layer thickness is set to 3 to 15 μm.

(C) Intermediate layer (TiC layer, TiN layer, Ti
CN layer, TiCO layer, TiNO layer, and TiCNO
Layer) TiCN band phase constituting the lower layer and α- and κ-A
adhesion between l ₂ O ₃ layer is relatively low, if the both are laminated directly, but cause a hard coating layer peeling, these layers are all the TiCN band phase, further α-
It is firmly adhered to both the Al ₂ O ₃ layer and the κ-Al ₂ O ₃ layer, and thus has an effect of improving the adhesion between the constituent layers of the hard coating layer. Does not have the effect of improving the adhesion, while the layer thickness is 5 μm.
If it exceeds m, chipping or chipping is likely to occur in the cutting edge portion, so the layer thickness is set to 0.5 to 5 μm.

(D) Upper layer (α-Al ₂ O ₃ layer and κ-
Al ₂ O ₃ layer) Since 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, the rake face in the cutting edge portion However, when the layer thickness is less than 0.5 μm, the desired effect of improving the wear resistance cannot be obtained. On the other hand, when the layer thickness exceeds 10 μm, the cutting edge lacks. Since layering and chipping easily occur, the layer thickness is set to 0.5 to 10 μm.

(E) Surface layer (TiN layer) Since the TiN layer itself has a golden color tone, it is formed to make it easy to identify the cutting tip before and after use. Therefore, when the layer thickness is less than 0.1 μm, the application of the color tone is insufficient, and on the other hand, the layer thickness up to 2 μm is sufficient, so the layer thickness is set to 0.1 to 2 μm. .

(F) Overall Average Layer Thickness of Hard Coating Layer When the layer thickness is 5 μm, the desired excellent wear resistance cannot be ensured. On the other hand, when the layer thickness exceeds 20 μm,
Since chipping and chipping easily occur in the cutting edge,
The overall average layer thickness was determined to be 5 to 20 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, 1.2 μm ZrC powder, 1.3 μm
m (Ta, Nb) C (TaC / NbC = 90/10)
Powder, 1 μm Cr powder, and 1.2 μm Co powder
Powders are prepared, and these raw material powders are blended in the composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and then pressed into a green compact of a predetermined shape. By performing vacuum sintering under the conditions shown in Table 1, carbide substrates A to E having a shape conforming to ISO • CNMG120412 were respectively manufactured. Further, the cemented carbide substrate E was heated to 80 Torr in a CH ₄ gas atmosphere at a temperature of 1: 1.
After holding at 420 ° C. for 1 hour, a slow cooling carburization treatment is performed, and after the treatment, carbon and Co adhering to the surface of the super hard substrate are removed by acid and barrel polishing, so that the maximum Co content at a position of 10 μm from the surface is obtained. Amount: 17.2% by weight, depth: 36μ
A Co-enriched zone of m was formed on the surface of the substrate. In addition, the sintered body C was provided with a Co-enriched zone having a maximum Co content of 9.5% by weight and a depth of 23 μm at a position of 17 μm from the surface on the surface of the super-hard substrate C. In the base D,
Maximum Co content on the surface at a position 20 μm from the surface: 1
A Co-enriched zone of 1.6% by weight and a depth of 27 μm was respectively formed, and the remaining carbide substrates A and B had no homogenous structure, and had an overall homogeneous structure. I had it. Table 1 shows that the super hard substrates A to E
Of each sample (Rockwell hardness A scale).

Next, the surface of each of these superhard substrates A to E was subjected to honing processing, and a conventional chemical vapor deposition apparatus was used.
Under the conditions shown in Japanese Patent Application Laid-Open No. 010-101, a hard coating layer having a layer configuration and an average layer thickness shown in Tables 3 and 4 is formed under the conditions shown in Table 3 below. Hard chips 1 to 10 and comparative coated super hard chips 1 to 10 were produced, respectively.

Next, the coated carbide tips 1 to 1 according to the present invention will be described.
0 and the comparative coated carbide tips 1 to 10 Work material: SCM440 lengthwise round bar with four longitudinal grooves, cutting speed: 300 m / min. Infeed: 1.5 mm Feed: 0.45 mm / rev. , Cutting time: 10 minutes, Dry high-feed intermittent cutting test of alloy steel under the following conditions: Work material: S45C round bar with four longitudinal grooves at regular intervals in the longitudinal direction, Cutting speed: 300 m / min. Infeed: 4.5 mm Feed: 0.3 mm / rev. , Cutting time: 10 minutes, dry high cut intermittent cutting test of carbon steel under the conditions of
In each cutting test, the flank wear width of the cutting edge was measured.
Table 5 shows the results of these measurements.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

[Table 4]

[0019]

[Table 5]

[0020]

From the results shown in Table 5, it can be seen that the lower layer of the hard coating layer has an alternately stacked structure with the TiCNO band phase starting from the TiCN band phase and ending with the TiCN band phase, and has a continuous longitudinal shape throughout these band phases. Each of the coated carbide tips 1 to 10 according to the present invention, which are constituted by a two-phase stacked layer formed with a growth crystal structure, has chipping or chipping at the cutting edge due to the high toughness of the two-phase stacked layer. In contrast, the comparative coated carbide tips 1 to 10 in which the lower layer of the hard coating layer is formed of an l-TiCN layer, while exhibiting excellent cutting performance, are all due to insufficient toughness of the l-TiCN layer. In interrupted cutting under heavy cutting conditions for steel requiring high toughness, chipping and chipping occur at the cutting edge,
It is clear that the service life can be reached in a relatively short time. As described above, the coated cemented carbide tip of the present invention is not limited to continuous cutting and intermittent cutting of various steels under ordinary conditions, for example.
In particular, it shows excellent fracture resistance even when performing intermittent cutting requiring extremely high toughness under heavy cutting conditions such as high feed and high depth of cut, and exhibits excellent wear resistance over a long period of time. Is what you do.

Continuing on the front page (72) Inventor ▲ Issue Toshi 1511 Furamaki, Oshiki, Ishishita-cho, Yuki-gun, Ibaraki Prefecture Inside the Tsukuba Works, Mitsubishi Materials Corporation (72) Inventor Yuki Hamaguchi 1511 Furimagi, Ishishita-cho, Yuki-gun, Ibaraki Prefecture Mitsubishi Materials Corporation Tsukuba Works (72) Inventor Masayuki Miichi 1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Pref. Mitsubishi Materials Corporation Tsukuba Works (56) References JP-A-11-117264 (JP, A) Kaihei 7-136808 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B23B 27/14 C23C 14/00-16/56

Claims (1)

(57) [Claims] 1. A surface of a tungsten carbide-based cemented carbide substrate, comprising: (a) a titanium nitride layer having a granular crystal structure having an average layer thickness of 0.1 to 2 μm as a lowermost layer; It has an average layer thickness of 15 μm, has an alternating stacking structure with the titanium carbonitride zone phase starting from the titanium carbonitride zone phase and ending with the titanium carbonitride zone phase along the thickness direction, and (C) an intermediate layer having an average layer thickness of 0.5 to 5 μm and a Ti carbide layer and a nitride layer each having a granular crystal structure, One or more of a carbonitride layer, a carbonate layer, a carbonitride layer, and a carbonitride layer, (d) a granular crystal structure having an average layer thickness of 0.5 to 10 μm as an upper layer Α-type and / or κ-type aluminum oxide layer (E) As a surface layer, a titanium nitride layer having a granular crystal structure having an average layer thickness of 0.1 to 2 μm, and a hard coating layer composed of the above (a) to (e) having an overall average layer thickness of 5 to 20 μm Slow-way cutting inserts made of surface-coated cemented carbide with excellent fracture resistance, obtained by chemical vapor deposition and / or physical vapor deposition.