JP3087504B2 - Manufacturing method of surface-coated tungsten carbide based cemented carbide cutting tools with excellent wear and fracture resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention has excellent wear resistance and chipping resistance, and is particularly useful for heavy cutting such as high feed cutting and high cutting of steel, which requires chipping resistance. The present invention relates to a method for producing 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, in general, for example, in continuous cutting or intermittent cutting of steel under ordinary conditions, in terms of weight% (mass%) (weight% and mass% show substantially the same ratio, the following Weight%, ie, weight%), Co and / or Ni
Metal bonded phase mainly composed of: 5-20%, the remainder being made of a hard phase mainly composed of WC. ,
Carbonitrides, carbonates, nitrides, and carbonitrides, and aluminum oxides (hereinafter, TiC, Ti
N, TiCN, TiCO, TiNO, and TiCN
O and Al ₂ O ₃ ), a surface-coated WC-based cemented carbide formed by forming a hard coating layer composed of one kind of single layer or two or more kinds of layers with an average layer thickness of 1 to 15 μm. It is well known that cutting tools are used. Further, for example, as described in JP-A-2-254144, for the purpose of improving fracture resistance, and thereby improving wear resistance in heavy cutting such as high-feed cutting or high-cut cutting of steel, for example. The surface-coated WC-based cemented carbide is obtained by subjecting the surface of the cutting tool made of the surface-coated WC-based cemented carbide to shot peening to form cracks positively and uniformly in a hard coating layer constituting the cutting tool. Cutting tools are also known.

[0003]

On the other hand, in recent years, it has been remarkable that FA and labor saving of cutting work have been remarkable, and accordingly, there has been a strong demand for versatility of cutting tools which is less affected by cutting conditions. Conventional surface-coated WC-based cemented carbide cutting tools, in which shot peening cracks are uniformly present in the above-mentioned hard coating layer, show excellent wear resistance in heavy-duty cutting under normal conditions, but have a higher speed. In such a case, the wear progresses remarkably rapidly, 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 viewpoint as described above, the conventional surface coating W in which the shot peening cracks are uniformly distributed in the hard coating layer.
As a result of conducting research to solve the problems of the cutting tool made of C-base cemented carbide, when manufacturing the above-mentioned surface-coated cutting tool made of WC-based cemented carbide, the formation of the hard coating layer constituting the cutting tool was 2 times. The hard coating layer formed first is preferably 20% in a ratio to the total thickness of the hard coating layer.
A shot peening treatment is applied to the hard coating layer having a thickness of about 80% to obtain a shot peening-formed crack distribution layer, and the remaining hard coating layer is also subjected to chemical vapor deposition to form a surface of the shot peening-formed crack distribution layer. When formed, the resulting surface-coated WC-based cemented carbide cutting tool has excellent fracture resistance due to the shot peening formed crack distribution layer in the lower portion of the hard coating layer on the base side, while remaining The superior upper part of the surface ensures excellent wear resistance.
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, the wear progress will be significantly suppressed, and excellent cutting performance will be exhibited over a long period of time The research result was obtained.

The present invention has been made on the basis of the above-mentioned research results, and comprises a metal binder phase mainly composed of Co and / or Ni: 5 to 20%, with the balance being mainly composed of WC. When forming a hard coating layer having an average layer thickness of 1 to 15 μm on the surface of a WC-based cemented carbide substrate composed of a phase, (a) First, TiC, TiN, TiC
N, TiCO, TiNO, TiCNO, and Al ₂ O
After forming a hard coating layer composed of one kind of single layer or two or more kinds of _three layers, shot peening is performed on the hard coating layer to form a shot peening formed crack distribution layer. (B) a) On the surface of the shot peening formed crack distribution layer, the above-mentioned TiC, TiN, TiCN, TiCO, TiN
By forming a hard coating layer composed of a single layer of O, TiCNO, and Al ₂ O ₃ or a multilayer of two or more types, a surface coating WC having excellent wear resistance and chipping resistance can be obtained.
The present invention is characterized by a method of manufacturing a base cemented carbide cutting tool.

In the method of manufacturing a cutting tool according to the present invention, the content of the metal binder phase in the substrate constituting the cutting tool is set to 5 to 2%.
The reason why the content is set to 0% is that if the content is less than 5%, the sinterability deteriorates, and sufficient strength cannot be ensured for the substrate, while if the content exceeds 20%, the hardness decreases. This is because the wear of the substrate itself is rapidly accelerated. In the method for manufacturing a cutting tool according to the present invention, the average thickness of the hard coating layer is limited to 1 to 15 μm. If the average thickness is less than 1 μm, a desired effect of improving wear resistance cannot be obtained. When the average layer thickness exceeds 15 μm, it is based on the reason that chipping or chipping (micro chipping) occurs on the cutting edge.

[0007]

Next, a method for producing a surface-coated WC-based cemented carbide cutting tool according to the present invention will be described in detail with reference to examples.
As the raw material powder, WC powder, TiC powder, TiN powder, each having a predetermined average particle size in the range of 1 to 6 μm,
TaC powder, NbC powder, Cr ₃ C ₂ powder, VC powder,
A Co powder and a Ni powder are prepared, and these raw material powders are blended in the composition shown in Table 1, wet-mixed for 72 hours by a ball mill, and then press-molded into a green compact at a pressure of 1 ton / cm ² (98 MPa). Then, this green compact is 10-1
In a nitrogen atmosphere at a predetermined partial pressure of N ₂ within a range of 00 torr (1.3 to 13 KPa), sintering is performed at a predetermined temperature within a range of 1380 to 1430 ° C. for 1 hour, and throw-away according to ISO standard SNNM432. W having a chip shape
C-base cemented carbide substrates A to I were formed.

Next, a single-layer or multiple-layer hard coating layer having a composition and an average layer thickness marked with * in Table 2 is formed on the surfaces of the substrates A to I using a conventional chemical vapor deposition apparatus. In addition, shot: cast iron ball having an average particle diameter of 0.4 mm, projection speed: 60 m / sec, projection time: 3 minutes, shot peening is performed, and this is used as a shot peening formed crack distribution layer. Then, the method of the present invention was carried out by forming a single-layer or multiple-layer hard coating layer having the same composition and average layer thickness as shown in Table 2, and shot peening the lower portion of the hard coating layer on the substrate side. A cutting tool made of a surface-coated WC-based cemented carbide of the present invention having a formed crack distribution layer (hereinafter, referred to as a coated cutting tool of the present invention)
1 to 13 were each manufactured.

For the purpose of comparison, the compositions corresponding to each of the coated cutting tools 1 to 13 of the present invention manufactured by the above-described method of the present invention using the same chemical vapor deposition apparatus on the surfaces of the above substrates A to I. And after forming the entire hard coating layer having an average thickness, shot: cast iron ball having an average particle size of 0.4 mm; projection speed: 60 m / sec; projection time: 3 minutes; The conventional method is performed by forming a shot peening forming crack having a uniform crack distribution density in the hard coating layer, and a cutting tool made of a surface-coated WC-based cemented carbide (hereinafter referred to as a conventional coated cutting tool).
1 to 13 were manufactured respectively.

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 with a microscope, and the length of the hard coating layer at the interface between the substrate and the outermost surface was: The number of cracks within 1 mm was visually measured at any five locations. The measurement results are shown in Tables 3 and 4 as average values.

Further, the above-mentioned various coated cutting tool, work material: SNCM439 (Hardness: H _B 260) round bar, Cutting speed: 230 m / min, 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-cut cutting test of steel was performed, and the flank wear width of the cutting edge was measured in each test. These measurement results are also shown in Tables 3 and 4.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

[0016]

According to the results shown in Tables 1 to 4, all the coated cutting tools are excellent in chipping resistance. Therefore, even if a high cutting depth test of steel requiring chipping resistance is performed, the cutting speed is reduced. Under normal cutting conditions of 150 m / min, there is no chipping or chipping on the cutting edge, but the cutting speed is 230 m / min.
In the case of high-speed cutting at m / min, the coated cutting tools 1 to 13 of the present invention, in which only the lower part of the hard coating layer on the substrate side is a shot peening-formed crack distribution layer, use the shot peening-formed crack distribution layer as the entire hard coating layer. It is clear that the abrasion resistance is much higher than that of the conventional coated cutting tools 1 to 13 described above. As described above, according to the method of the present invention, a surface-coated WC-based cemented carbide cutting tool can produce a surface-coated WC-based cemented carbide cutting tool having excellent wear resistance and chipping resistance. Therefore, when it is used for heavy cutting of steel, for example, which is required to have high fracture resistance, the wear progress is remarkably suppressed even when the cutting is performed at high speed. It demonstrates excellent cutting performance.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B23B 27/14 B23P 15/28 C04B 35/56 C23C 16/30

Claims (1)

(57) [Claims] 1. A tungsten carbide-based cemented carbide substrate comprising a metal binder phase mainly composed of Co and / or Ni: 5 to 20% by weight (mass%), the remainder being a hard phase mainly composed of tungsten carbide. When a hard coating layer having an average layer thickness of 1 to 15 μm is formed on the surface of (a), first, a carbide, nitride,
After forming a hard coating layer comprising a single layer or a multilayer of two or more of carbonitride, carbonate, nitroxide, and carbonitride, and aluminum oxide, this is subjected to shot peening treatment. To form a shot peening-formed crack distribution layer. (B) Then, on the surface of the shot peening-formed crack distribution layer of (a), the above-mentioned Ti carbide, nitride, and carbon Forming a hard coating layer composed of a single layer or a multilayer of at least one of nitride, carbonate, nitroxide, and carbonitride, and aluminum oxide. Method for manufacturing surface-coated tungsten carbide based cemented carbide cutting tools with excellent fracture and fracture resistance.