JPH06246513A - Cutting tool made of surface coating silicon-nitride group ceramics with excellent adhesion of hard coating layer - Google Patents

Abstract

PURPOSE:To provide a cutting tool made of a surface coating WC-group cemented carbide with excellent abrasion resistance and defect resistance. CONSTITUTION:On the surface of a WC-group cemented carbide base body which contains a metallic bond layer whose main components are Co and/or Ni: 5-20weight% and the rest formed of a hard layer mainly consisting of WC, a hard coating layer composed of one kind of single layer or multiple layers of two or more kinds of TiC, TiN, TiCN, TiCO, TiNO, TiCNO and Al2O3 is formed with average layer thickness of 1-15mum. The lower part on base body side of the hard coating layer is made a shot peening formed crack distributed layer.

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-described surface-coated WC-based cemented carbide cutting tool, the hard coating layer constituting the surface-coated lower portion of the base side is Desirably, cracks formed by shot peening are distributed in a layer thickness of 20 to 80% with respect to the total layer thickness of the hard coating layer.
In the C-based cemented carbide cutting tool, excellent fracture resistance is secured by the shot peening formation crack distribution layer in the lower portion on the substrate side of the hard coating layer, while excellent wear resistance is obtained by the remaining upper portion on the surface side. Since it is ensured that fracture resistance is required, for example, even if heavy cutting of steel is performed at high speed, the cutting edge will not be chipped or chipped, and the progress of wear will be significantly suppressed, and for a long time We obtained the research results that show excellent cutting performance.

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 second aspect, the lower portion of the hard coating layer on the substrate side is a shot peening formation crack distribution layer, which is characterized in that abrasion resistance and fracture resistance are improved.

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 of the present invention
The manufacturing tool will be specifically described by way of examples. Raw powder
As a predetermined average particle size within the range of 1 to 6 μm
WC powder, TiC powder, TiN powder, TaC powder having
Powder, NbC powder, Cr₃C₂Powder, VC powder, Co powder
Powder and Ni powder were prepared, and these raw material powders are shown in Table 1.
Formulated in the composition shown and wet in a ball mill for 72 hours
After mixing, 1ton / cm²Press forming into green compact with pressure
Then, apply the green compact to a predetermined amount within the range of 10 to 100 torr.
N ₂Range of 1380 to 1430 ° C. in partial pressure nitrogen atmosphere
ISO standard by sintering at a predetermined temperature for 1 hour
W with throwaway tip shape of SNMN432
C-based cemented carbide substrates A to I were formed.

Then, a single or multiple hard coating layer having the composition and average layer thickness marked with "*" in Table 2 is formed on the surface of each of the substrates A to I by using a normal chemical vapor deposition apparatus. , Shot: cast iron spheres having an average particle size of 0.4 mm, shot speed: 60 m / sec, shot time: 3 minutes, and shot peening was performed as a shot peening formation crack distribution layer. Then, by forming a single-layer or multiple-layer hard coating layer having the same composition and average layer thickness as shown in Table 2 above, the crack distribution densities differ, but the lower portion of the hard coating layer on the substrate side. The surface-coated WC-based cemented carbide cutting tools of the present invention (hereinafter referred to as the present coated cutting tools) 1 to 13 were manufactured by using as a shot peening formation crack distribution layer.

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 size of 0.4 mm, projection speed: 60 m / sec, projection time: 3 minutes, shot peening was performed, and 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 SNCM439 (hardness: H _B 260), cutting speed: 230 m / min, depth of cut: 4 mm, feed: 0.25 mm / rev., cutting time: 30 min, continuous high cut speed cutting test of the steel under the condition of, and, workpiece: SNCM439 (hardness: H _B 260) round bar, cutting speed: 150 meters / min, cut: 4 mm, feed : 0.25 mm / rev., Cutting time: 30 minutes, a continuous high cutting depth cutting test of steel was performed, and the flank wear width of the cutting edge was measured in each test. 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, since all of the coated cutting tools have excellent fracture resistance, the cutting speed is high even if a high-cut cutting test for steel requiring fracture resistance is performed. Under normal cutting conditions of 150 m / min, the cutting edge will not be chipped or chipped, but the cutting speed is 230
In the case of high-speed cutting of m / min, the coated cutting tools 1 to 13 of the present invention, in which only the lower portion of the hard coating layer on the substrate side is a shot peening formation crack distribution layer, the whole hard coating layer is a shot peening formation crack distribution layer. It is obvious that the coated cutting tools 1 to 13 have excellent wear resistance. As described above, since the surface-coated WC-based cemented carbide cutting tool of the present invention has excellent wear resistance and fracture resistance, it was used for heavy cutting of steel for which fracture resistance is particularly required. In this case, even if this is performed by high-speed cutting, the progress of wear is significantly suppressed, so that excellent cutting performance is exhibited over a long period of time.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // B24C 1/10 A 7411-3C

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. A surface-coated tungsten carbide based cemented carbide cutting tool formed with an average layer thickness of 15 μm, characterized in that the lower part of the hard coating layer on the substrate side is a shot peening formation crack distribution layer. And surface-coated tungsten carbide based cemented carbide cutting tool with excellent fracture resistance.