JP3236910B2 - Surface-coated tungsten carbide based cemented carbide cutting tool with excellent fracture resistance with hard coating layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool made of a surface-coated tungsten carbide-based cemented carbide having a hard coating layer having excellent fracture resistance (hereinafter referred to as a coated carbide cutting tool).

[0002]

2. Description of the Related Art Conventionally, a tungsten carbide-based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate) is generally coated with an average layer thickness of 0.1 to 4 μm by chemical vapor deposition or physical vapor deposition. Carbide of Ti having Ti (hereinafter referred to as TiC)
Layer, nitride (hereinafter referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, carbonate (hereinafter referred to as TiCO) layer, nitride oxide (hereinafter referred to as TiNO) layer, and carbon An oxide having an average layer thickness of 0.2 to 2 μm and at least one of a nitrided oxide (hereinafter referred to as TiCNO) layer (hereinafter collectively referred to as a Ti carbon / nitride / oxide layer) A coated carbide cutting tool in which a hard coating layer composed of an aluminum (hereinafter, referred to as Al ₂ O ₃ ) layer is formed with an average layer thickness of 1 to 6 μm is known. It is also well known that tools are used for continuous cutting and interrupted cutting of steel or cast iron, for example.

[0003]

On the other hand, in recent years, there has been a strong demand for higher efficiency and labor saving in cutting, and with this, cutting has tended to be performed at higher speeds and heavy cutting such as high feed and high cutting. However, in the above-mentioned conventional coated carbide cutting tool, it is used for milling (intermittent cutting) of steel or cast iron, for example, under severe conditions where high toughness such as high speed and high feed and high depth of cut is required. When used, the cutting edge tends to be chipped or chipped (small chipping) due to lack of toughness of the hard coating layer, and 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, attention was paid to the hard coating layer of the conventional coated carbide cutting tool, and a study was conducted to improve the fracture resistance of the hard coating layer.
(% By weight) (% indicates weight% (% by weight)),
An amorphous composite oxide layer of Al, Si, and Ti (hereinafter, referred to as an amorphous layer) containing Si: 1 to 20% and Ti: 0.1 to 10% is added to form the hard coating layer. Ti charcoal
When one or more of nitrides and oxides, an Al ₂ O ₃ layer, and an amorphous layer are used, the resulting hard coating layer has excellent toughness without deterioration in wear resistance. Therefore, coated carbide cutting tools formed with this hard coating layer can be used for cutting edges even when heavy cutting such as high feed and high depth of cut requiring high toughness is performed intermittently and at high speed. We have obtained research results that demonstrate excellent cutting performance over a long period of time without chipping or chipping.

The present invention has been made on the basis of the above research results, and a hard coating layer having a thickness of 1 to 6 μm is formed on the surface of a superhard substrate by a chemical vapor deposition method and / or a physical vapor deposition method.
In the coated carbide cutting tool formed with an average layer thickness of m, the hard coating layer is one of a carbon, nitride and oxide layer of Ti having an average layer thickness of 0.1 to 4 μm. The above, an Al ₂ O ₃ layer having an average layer thickness of 0.2 to ₂ μm, and an Al ₂ O ₃ layer having an average layer thickness of 0.2 to ₂ μm,
The hard coating layer is characterized by being a coated carbide cutting tool having an excellent fracture resistance, comprising an amorphous layer containing -20% and Ti: 0.1-10%. .

Next, the reasons for limiting the numerical values of the coated carbide cutting tool of the present invention as described above will be described. (A) Average thickness of the hard coating layer If the average layer thickness is less than 1 μm, the desired wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 6 μm, particularly severe toughness is required. Under an appropriate cutting condition, chipping and chipping are likely to occur in the cutting blade. Therefore, the average layer thickness is set to 1 to 6 μm, preferably 2 to 4.5 μm.

(B) Average thickness of the carbon / nitride / oxide layer of Ti If the average thickness is less than 0.1 μm, the hard coating layer tends to become brittle, and the cutting edge tends to chip. On the other hand, if the average layer thickness exceeds 4 μm, the progress of wear will be accelerated, so that the average layer thickness is 0.1 to 4 μm,
Desirably, it is set to 0.3 to 3 μm.

(C) Average layer thickness of Al ₂ O ₃ layer If the average layer thickness is less than 0.2 μm, desired abrasion resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 2 μm, Since the fracture resistance is reduced, the average layer thickness is set to 0.2 to 2 μm, preferably 0.5 to 1.5 μm.
μm.

(D) Average thickness of the amorphous layer If the average thickness is less than 0.2 μm, the hard coating layer cannot be provided with the desired excellent toughness, while the average thickness exceeds 2 μm. And the abrasion resistance rapidly decreases, the average layer thickness is set to 0.2 to 2 μm, preferably 0.5 to 1.5 μm. Note that the content ratio of Si and Ti in the amorphous layer was S
i: 1 to 20% and Ti: 0.1 to 10%,
This is because, when the content ratio of either Si or Ti is less than 1% Si and less than 0.1% Ti, it becomes difficult to form an amorphous phase, and the crystallization is strengthened to obtain the desired excellent toughness. Cannot be secured, while Si and T
If any of i exceeds 20% of Si and 10% of Ti, it softens rapidly and the wear progress of the layer itself is accelerated,
This is because it causes a decrease in the wear resistance of the hard coating layer, and is desirably 5 to 10% for Si and 1 for Ti.
The content is preferably up to 5%.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated carbide cutting tool of the present invention will be specifically described with reference to examples. As raw material powders, WC powder having an average particle size of 5 μm (coarse particle) and 0.5 μm (fine particle), and 1.2 μm (Ti, W) CN [T
iC / TiN / WC = 24/20/56 by weight ratio], 1.3 μm (Ta, Nb) C [TaC / NbC]
= 90/10 by weight ratio] Using powder, 1.0 µm Cr powder, and 1.2 µm Co powder, these raw material powders were blended in the blending composition shown in Table 1, and wet-mixed in a ball mill for 72 hours. After drying, the mixed powder is subjected to IS
Press compacted into a green compact having a shape conforming to the O standard SEEN1204AFTN1, and the green compact was vacuum-sintered under the same conditions as shown in Table 1 to produce carbide substrates A to E, respectively. Then, after machining the above-mentioned super hard substrates A to E into a predetermined shape and performing honing, the surface of each super hard substrate was coated on the surface of each super hard substrate under the conditions shown in Table 2 using an ordinary chemical vapor deposition apparatus. By forming a hard coating layer having the composition and average thickness shown in FIGS.
To 12 and conventional coated carbide cutting tools 1 to 12, respectively.

Next, among the coated carbide cutting tools obtained as a result, the coated carbide cutting tools 1 to 7 according to the present invention and the conventional coated carbide cutting tools 1 to 7 were prepared using a work material: FC300 (hardness). : square bar cutting speed of _{H B 180):. 400m /} min, feed:. 0.35 mm / rev, cut: 2 mm, cutting time: perform wet high-speed high feed milling tests cast iron 10 minutes, conditions, also the present invention coated cemented carbide for cutting tools 6-12 and conventional coated carbide cutting tools 6-12, workpiece: SCM440 (hardness: H _B 220) square bar of cutting speed:. 300 meters / min, feed: 0 .38 mm / rev., Depth of cut: 2 mm, cutting time: 10 minutes, a dry high-speed high-feed milling test of steel was performed, and the flank wear width of the cutting edge was measured in each test.
Table 5 shows the results of these measurements.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

[0016]

[Table 5]

[0017]

According to the results shown in Table 5, the coated carbide cutting tools 1 to 12 according to the present invention were obtained by using the carbon / nitride / oxide layer of Ti and the Al
Because of its toughness excellent hard coating layer is composed of ₂ O ₃ layer and the amorphous layer, milling the (interrupted cut) at a high speed, and also lack the cutting edge is performed at high feed and high cut conditions While it shows excellent wear resistance without occurrence of chipping and chipping, conventional coated carbide cutting tools 1 to 12 are required to have particularly high toughness because the hard coating layer does not have sufficient toughness. Under the severe cutting conditions described above, it is apparent that chipping occurs on the cutting edge in a relatively short time, which leads to a long service life. As described above, the coated carbide cutting tool of the present invention has a hard coating layer having excellent toughness, so that the hard coating layer exhibits excellent fracture resistance even under severe cutting conditions, Therefore, it is possible to sufficiently satisfy cutting efficiency and labor saving in cutting work.

Continuing from the front page (72) Inventor ▲ Isao ▼ Hitoshi Toki 1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Pref. Mitsubishi Materials Corporation Tsukuba Works (56) References JP-A-59-219465 (JP, A) JP-A-58-144467 (JP, A) JP-A-59-28565 (JP, A) JP-A-59-219463 (JP, A) JP-A-62-290870 (JP, A) (A) JP-A-1-295702 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23B 27/14 C23C 14/00-14/08 C23C 16/30-16/40

Claims (1)

(57) [Claims] 1. A surface-coated tungsten carbide-based superalloy formed by forming a hard coating layer with an average thickness of 1 to 6 μm on the surface of a tungsten carbide-based cemented carbide substrate by a chemical vapor deposition method and / or a physical vapor deposition method. In a hard alloy cutting tool, the hard coating layer may be formed of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonitride layer, a nitrogen oxide layer, and a Ti layer each having an average layer thickness of 0.1 to 4 μm. One or more of carbonitride oxide layers, an aluminum oxide layer having an average layer thickness of 0.2 to 2 μm, an average layer thickness of 0.2 to 2 μm, and Si: 1 to 20% by weight ( %, And an amorphous composite oxide layer of Al, Si and Ti containing 0.1 to 10% by weight (% by mass) and Ti: excellent fracture resistance. Cutting tool made of surface-coated tungsten carbide based cemented carbide.