JPH06246512A - Cutting tool made of surface coating tungsten carbide-group cemented carbide alloy with excellent abrasion resistance and defect resistance - Google Patents

Abstract

PURPOSE:To attain excellent abrasion resistance and defect resistance by disposing shot peening forming crack on a hard coating layer formed on the surface of a tungsten carbide-group cemented carbide alloy, and setting the crack distribution concentration higher at a lower part on the base substance side than that on the surface side upper part. CONSTITUTION:This cutting tool is formed with its hard coating layer which has average layer thickness of 1-15mum on the surface of a tungsten carbide-group cemented carbide alloy base substance. The base substance contains 5-20weight% of metallic combined phase which is mainly composed of Co and/or Ni, and the rest is composed of a hard phase which is mainly composed of tungsten carbide. The hard coating layer is formed with a single layer of one kind or multiple layers of at least two kinds from among Ti carbide, nitriding, aluminum oxide and so on. A shot peening forming crack whose crack distribution concentration differs from each other at an upper part on the surface side and a lower part on the base substance side is disposed on the hard coating layer. The crack distribution concentration is set higher on the lower part on the base substance side than that on the upper part on the surface side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent wear resistance and fracture resistance, and is particularly suitable for heavy cutting such as high feed cutting and high depth cutting of steel which requires fracture resistance. The present invention relates to a surface-coated tungsten carbide (hereinafter referred to as WC) based cemented carbide cutting tool that exhibits excellent wear resistance when used for high speed cutting.

[0002]

2. Description of the Related Art Conventionally, for example, in continuous cutting or interrupted cutting of steel under normal conditions, a metallic binder phase mainly composed of Co and / or Ni in weight% (hereinafter,% means weight%): On the surface of a WC-based cemented carbide substrate containing 5 to 20% and the rest consisting of a hard phase mainly composed of WC, a Ti carbide, a nitride, a carbonitride, or a carbonate of Ti is formed by a chemical vapor deposition method.
Nitride oxide, carbonitride oxide, and aluminum oxide (hereinafter, TiC, TiN, TiCN, TiC, respectively)
O, TiNO, and TiCNO, and Al ₂ O ₃ ), a surface coating formed by forming a hard coating layer composed of one single layer or two or more multiple layers with an average layer thickness of 1 to 15 μm. It is well known that WC-based cemented carbide cutting tools are used. Also, for example, Japanese Patent Laid-Open No.
As described in JP-A-254144, for the purpose of improving fracture resistance, and thus improving wear resistance in heavy cutting such as high feed cutting and high depth cutting of steel, the above surface-coated WC group is used. A surface-coated WC-based cemented carbide cutting tool is also known in which shot peening is performed on the surface of the cemented carbide cutting tool, and cracks are positively and uniformly formed in the hard coating layer constituting the cutting tool. There is.

[0003]

On the other hand, in recent years FA cutting and labor saving in cutting processing have been remarkable, and along with this, there is a strong demand for versatility of cutting tools that is not easily affected by cutting conditions. The conventional surface-coated WC-based cemented carbide cutting tool in which shot peening-forming cracks are uniformly present in the above hard coating layer has excellent wear resistance in heavy cutting under normal conditions, but has a high speed. In such a case, the progress of wear becomes extremely fast, and the service life is reached in a relatively short time.

[0004]

Therefore, the present inventors have
From the viewpoint as described above, the conventional surface coating W in which the shot peening formation cracks are uniformly distributed in the hard coating layer described above.
As a result of research to solve the problems of the C-based cemented carbide cutting tool, in the above-mentioned surface-coated WC-based cemented carbide cutting tool, the hard coating layer constituting the surface-coated upper part is If shot peening formation cracks having different crack distribution densities are present in the lower part on the substrate side, and the crack distribution density is made higher in the lower part on the substrate side than in the upper part on the surface side, Surface coating W
The research results show that the C-based cemented carbide cutting tool exhibits excellent wear resistance even when heavy cutting of steel is performed at high speed, and exhibits excellent cutting performance for a remarkably long period of time.

The present invention has been made based on the above-mentioned research results, and contains a metal binder phase containing Co and / or Ni as a main component: 5 to 20%, and the rest containing WC as a main component. TiC, TiN, TiCN, TiCO, TiNO, on the surface of the WC-based cemented carbide substrate composed of phases,
A surface-coated WC-based cemented carbide cutting tool formed by forming a hard coating layer consisting of one single layer or two or more multiple layers of TiCNO and Al ₂ O ₃ with an average layer thickness of 1 to 15 μm. In the above hard coating layer, shot peening forming cracks having different crack distribution densities in the upper surface side portion and the lower body side portion are present, and the crack distribution density is higher than that of the surface side upper portion. This is characterized by a surface-coated WC-based cemented carbide cutting tool whose wear resistance and fracture resistance are improved by making the lower side portion higher.

In the cutting tool of the present invention, the content of the metallic binder phase in the base material constituting the cutting tool is set to 5 to 20%. If the content is less than 5%, the sinterability is lowered and the base material is However, if the content exceeds 20%, the hardness decreases, and the progress of wear of the substrate itself is rapidly accelerated. Moreover, the average layer thickness of the hard coating layer constituting the cutting tool of the present invention is limited to 1 to 15 μm because the desired wear resistance improving effect cannot be obtained when the average layer thickness is less than 1 μm, while the average value This is based on the reason that when the layer thickness exceeds 15 μm, chipping or chipping (fine chipping) occurs in the cutting edge.

[0007]

EXAMPLES Next, the surface-coated WC-based cemented carbide cutting tool of the present invention will be specifically described by way of examples. As raw material powders, WC powders, TiC powders, TiN powders, TaC powders, NbC powders, Cr ₃ C ₂ powders, VC powders, Co powders, and Ni powders each having a predetermined average particle size within the range of 1 to 6 μm Were prepared, and these raw material powders were blended to the blending composition shown in Table 1, wet-mixed for 72 hours in a ball mill, and then press-molded into a green compact at a pressure of 1 ton / cm ^2. W having a throwaway tip shape of ISO standard SNMN432 by sintering at a predetermined temperature in the range of 1380 to 1430 ° C. for 1 hour in a nitrogen atmosphere of a predetermined N ₂ partial pressure in the range of to 100 torr.
C-based cemented carbide substrates A to I were formed.

Then, for the purpose of forming a high-density crack distribution layer on the surface of the above-mentioned substrates A to I, first, for the purpose of forming a high-density crack distribution layer, a single layer having the composition and average layer thickness shown in Table 2 or After forming a multilayer hard coating layer (marked with * in Table 2), shot: cast iron ball having an average particle size of 0.4 mm, projection speed: 80 m / sec, projection time: 3 minutes For the purpose of performing shot peening and subsequently forming a low-density crack distribution layer, a single-layer or multiple-layer hard coating layer having the same composition and average layer thickness as shown in Table 2 is formed, and shot: Cast iron balls having an average particle size of 0.3 mm, shot speed: 40 m / sec, shot time: 1 minute, shot peening gives different crack distribution densities, but in each case Lower part on the substrate side Surface upper crack distribution density of the shot peening forming cracks than the portion higher present invention surface coating WC-based cemented carbide cutting tool (hereinafter, referred to as the present invention a coated cutting tool) 1 to 13 were prepared.

For the purpose of comparison, the same chemical vapor deposition apparatus is used on the surfaces of the above-mentioned substrates A to I, and a hard coating layer having a composition and an average layer thickness corresponding to each of the coated cutting tools 1 to 13 of the present invention. After forming, shot: peening iron balls having an average particle diameter of 0.4 mm, shot speed: 80 m / sec, shot time: 3 minutes, shot peening was performed under the following conditions to obtain a uniform crack distribution in the hard coating layer. Conventional surface-coated WC-based cemented carbide cutting tools (hereinafter referred to as conventional coated cutting tools) 1 to 13 were manufactured by forming shot peening formation cracks of high density.

Next, in order to examine the crack distribution density of the various coated cutting tools obtained as a result, the longitudinal section of the hard coating layer was observed under a microscope, and the lengths at the substrate interface and the outermost surface were: The number of cracks existing within 1 mm was visually measured at arbitrary 5 points. The results of this measurement are shown in Tables 3 and 4 as average values.

Regarding the above various coated cutting tools, the work material: a round bar of SCM440 (hardness: H _B 170), cutting speed: 250 m / min, depth of cut: 4.5 mm, feed: 0.3 mm / rev ., Cutting time: 30 minutes, a continuous high-incision high-speed cutting test of steel was performed, the flank wear width of the cutting edge was measured, and the work material: SCM440 (hardness: H _B 170) Round bar, cutting speed: 180 m / min, depth of cut: 4.5 mm, feed: 0.3 mm / rev., Cutting time: 30 minutes. The flank wear width of the blade was measured. The results of these measurements are also shown in Tables 3 and 4.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

[0016]

From the results shown in Tables 1 to 4, in the coated cutting tools 1 to 13 of the present invention, the crack distribution density of the shot peening forming cracks in the hard coating layer constituting the coated cutting tools 1 to 13 is the same as that of the upper portion on the surface side and the substrate. The lower side portion differs from the lower side portion and has a higher crack distribution density in the lower portion on the substrate side than in the upper portion on the surface side, whereas the conventional coated cutting tools 1 to 13 all have a hard coating layer. The two are different in that the crack distribution density of shot peening formation cracks is almost uniform over the entire layer, and as a result, the former requires high-cut cutting of steel under normal conditions as well as high-speed cutting. Although it shows excellent wear resistance and chipping resistance, the latter shows excellent chipping resistance and wear resistance without chipping or chipping of the cutting edge under normal conditions. , It is evident that exhibits a more rapid wear progress in high-speed cutting of les. As described above, the surface-coated WC-based cemented carbide cutting tool of the present invention is
Since it has excellent wear resistance and fracture resistance, especially when it is used for heavy cutting of steel, for example, when it is used for heavy cutting of steel, even if this is done at high speed cutting, wear progress is significantly suppressed , It shows excellent cutting performance over a long period of time.

Claims (1)

[Claims] 1. A metal-bonded phase mainly composed of Co and / or Ni: 5 to 20% by weight, and the balance consisting of a hard phase mainly composed of tungsten carbide on the surface of a tungsten carbide-based cemented carbide substrate, 1 to 1 of a hard coating layer composed of a single layer or two or more multi-layers of Ti carbide, nitride, carbonitride, carbon oxide, oxynitride, and oxycarbonitride, and aluminum oxide. In a surface-coated tungsten carbide-based cemented carbide cutting tool formed with an average layer thickness of 15 μm, in the hard coating layer, shot peening with different crack distribution densities in the upper part on the surface side and the lower part on the substrate side. A surface-coated carbonized material having excellent wear resistance and chipping resistance, characterized in that cracks are present and the crack distribution density is higher in the substrate-side lower portion than in the surface-side upper portion. Cutting tool made of Nungsten base cemented carbide.