JPH10337602A - Cutting tool made of surface covering cemented carbide and having thick artificial diamond covering layer having superior peeling resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce no peeling of a thick artificial diamond covering layer though the artificial diamond covering layer is in a thick film state in high-speed cutting as well as continuous cutting and intermittent cutting under ordinary conditions. SOLUTION: A cutting tool made of a surface covering cemented carbide is composed by forming a thick artificial diamond covering layer having an average layer thickness of 10-50 μm on the surface of a cemented carbide base composed of a tungsten carbide group cemented carbide. A continuous and/or discontinuous laser beam-machined notched vertical narrow groove having depth in the range of 1/2-1.5 times of the average layer thickness of the thick artificial diamond covering layer is formed on over an entire cutting edge local surface of at least any one of a cutting edge ridge line part intersecting the cutting face with the flank, the cutting face, or the flank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an artificial diamond coating layer formed on a surface of a cemented carbide substrate (hereinafter simply referred to as a cemented carbide substrate) made of a tungsten carbide-based cemented carbide by a gas phase synthesis method. , A surface-coated cemented carbide cutting tool that exhibits excellent peel resistance even if it is made thicker
(Referred to as coated carbide tool).

[0002]

2. Description of the Related Art Conventionally, generally, for example, JP-A-61-52
As described in, for example, JP-A-363-363, the surface of a superhard substrate is coated with a thermionic emission method described in JP-A-58-91100, and described in JP-A-58-110494. Microwave method and Japanese Patent Application Laid-Open No. 58-1351
No. 17, an artificial diamond coating layer is formed using a gas phase synthesis method such as a high-frequency plasma method.
A coated carbide tool formed with an average layer thickness of m is known, and this coated carbide tool is, for example, pure Al or Al-S
It is also well known that it is used for continuous cutting or intermittent cutting of non-metallic materials such as Al alloys such as i-alloys, non-ferrous metal materials such as Cu alloys, and carbon materials.

[0003]

On the other hand, in recent years, the use of FA in cutting devices has been remarkable, and there has been a strong demand for labor saving in cutting. With this, the artificial diamond coating layer in coated carbide tools has become thicker. Although the cutting process tends to be faster, the above-mentioned conventional coated carbide tools exhibit excellent cutting performance over a long period of time in continuous cutting or interrupted cutting under normal conditions. If this is used for high-speed cutting in a state where the film is thickened to an average layer thickness of 10 μm or more, peeling occurs in the thickened artificial diamond coating layer, and the service life is relatively short.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
In view of the above, in the state where the artificial diamond coating layer constituting the coated carbide tool is thickened, the coated carbide tool which does not cause peeling of the thickened artificial diamond coating layer even when used for high-speed cutting. (A) Generally, the artificial diamond coating layer constituting the coated carbide tool is formed at a relatively high temperature of 700 to 900 ° C.
After the formation of the artificial diamond coating layer, a large difference in heat shrinkage occurs between the cemented carbide substrate and the artificial diamond coating layer, which causes a large compressive residual stress in the artificial diamond coating layer. This tendency is further promoted by thickening the average layer thickness: 10 μm or more, so that the thickened artificial diamond coating layer has a still larger compressive residual stress, which causes peeling. thing. (B) In the coated carbide tool, at least any one of a cutting edge ridge portion where a rake face and a flank cross each other (hereinafter, simply referred to as a cutting edge ridge portion), a rake face, and a flank face. A continuous and / or discontinuous laser cut flute having a depth within a range of 1/2 to 1.5 times the average layer thickness of the thickened artificial diamond coating layer is formed on the entire local surface of the cutting blade. When formed over the surface, the compressive residual stress of the thickened artificial diamond coating layer on the local surface of the cutting edge in which the laser-processed cut vertical groove is formed is significantly reduced, and as a result, the coated carbide tool can cut the Demonstrates excellent peel resistance even when used for The research results shown in (a) and (b) above were obtained.

The present invention has been made on the basis of the above research results, and has a surface of a super-hard substrate of 10 to 50 μm.
In a coated carbide tool formed by forming a thickened artificial diamond coating layer with an average layer thickness of at least one of a cutting edge ridge portion, a rake face, and a flank, the local surface of the cutting edge has the thick film. Of the average layer thickness of the artificial diamond coating layer
/ 2 to 1.5 times the depth of the continuous and / or discontinuous laser cut vertical grooves formed over the entire local surface of the cutting edge, and the artificial diamond coating having a large thickness. It is characterized by a coated carbide tool whose layer has excellent peel resistance.

[0006] In the coated carbide tool of the present invention,
The average thickness of the thickened artificial diamond coating layer is 10 to 50.
If the average layer thickness is less than 10 μm, the desired excellent wear resistance cannot be ensured for a long period of time, while if the average layer thickness exceeds 50 μm, chipping or chipping of the cutting edge may occur. This is because chipping is likely to occur, and the average layer thickness is desirably 20 to 40 μm. The depth of the laser-processed vertical groove (hereinafter simply referred to as vertical groove) is preferably The reason why the average thickness of the film-forming artificial diamond coating layer is set to 1/2 to 1.5 times that when the depth is less than 1/2 the average layer thickness of the film-forming artificial diamond coating layer, It is difficult to reduce the compressive residual stress existing in the diamond coating layer to a level that does not cause delamination even when high-speed cutting is performed. On the other hand, when the depth exceeds 1.5 times the same, the fracture resistance sharply decreases. When chipping or chipping is likely to occur on the cutting blade, Cormorant is from reasons, preferably it is from a depth corresponding to the average layer thickness of the thicker artificial diamond coating layer to the depth of the 1.3-fold. Further, the vertical fine grooves can be formed under ordinary conditions using a widely known YAG laser processing machine or CO ₂ processing machine.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated carbide tool of the present invention will be specifically described with reference to examples. As the raw material powder, W having a predetermined average particle size in the range of 1 to 3 μm
A C powder, a Co powder, a TaC powder, and a Cr ₃ C ₂ powder were prepared, and these raw material powders were used for the carbide substrate A in terms of% by weight (hereinafter,% indicates% by weight), WC-2% Cr _Three
C ₂ -4% Co, WC-6% Co for the carbide substrate B,
WC-2% TaC-8% Co for carbide substrate C
And mixed in a ball mill for 72
After being wet-mixed for hours and dried, the mixture is pressed into a green compact at a pressure of 1.5 ton / cm ² , and these green compacts are
Sintered at 1400 ° C. for 1 hour, ground, and ground to have a chip shape conforming to ISO standard SPGN120412, and the honing applied to the ridge of the cutting edge is R: 0.05 m.
m of super-hard substrates A to C were respectively manufactured.

Next, as a pre-treatment, these super-hard substrates A to C are first subjected to a heat treatment for coarsening the surface WC grains in a nitrogen atmosphere at 1650 ° C. for 1 hour, followed by 5%
A surface etching treatment of immersion in a nitric acid aqueous solution for 10 minutes is performed to remove Co on the surface, and the average particle size is 0.5 μm.
In a state where ultrasonic surface damage treatment is performed for 10 minutes in an alcohol containing diamond powder dispersed and contained therein, a filament: metal tantalum, filament Temperature: 2200 ° C., ambient pressure: 50 torr, surface temperature of super-hard substrate: 800 ° C., reaction gas composition: CH ₄ / H ₂ = 1
By forming a thickened artificial diamond coating layer having an average layer thickness shown in Table 1 under the conditions described in Table 1, a comparative coating super-coated with a relatively thick artificial diamond coating layer as compared with the conventional coated carbide tool described above. Hard tools 1 to 10 were manufactured respectively.

Next, the comparative coated carbide tools 1 to 10
The YAG laser is used on at least any one of the cutting edge ridge, the rake face, and the flank of the cutting edge, and a repetition frequency of 1 to 60 KH in Ar gas.
_Under the conditions of _Z and average power: 7 W, the distributions shown in the simplified plan view and the simplified front view in FIG. 1 (the outermost surface measurement width of the vertical fine grooves: 6 μm, the pitch between the parallel fine vertical grooves:
0.8 mm), by forming vertical grooves in the combinations shown in Table 2 and at a depth, the coated super hard tool 1 of the present invention was obtained.
To 10 were respectively manufactured.

With respect to the resulting artificial diamond coating layers of various types of coated carbide tools obtained as a result, in the coated carbide tools 1 to 10 of the present invention, an arbitrary portion of the local surface of the cutting edge for forming a vertical groove, and In the case of the comparative coated carbide tools 1 to 10, the X-ray diffraction pattern of the corresponding part is
Target: Cu, measurement crystal plane: (331), measurement method: incident angle fixing method, normal angle (degree): 0, 18, 26,
33, 40, and 45, measurement angle: 2θ = 137.5-
145 degrees, step angle / time: 0.04 degrees / 5 seconds, current: 300 mA, voltage: 40 KV, entrance slit: none, light receiving slit: 12 mm, and the peak position is specified from this X-ray diffraction pattern. ： Half width midpoint method,
Young's modulus of diamond: 107100 Kg / mm ² ,
The compressive residual stress was calculated with the Poisson's ratio of diamond being 0.2. As a result, the coated carbide tools 1 to 10 of the present invention are:
All show a compressive residual stress in the range of 68 to 98 kg / mm ² , whereas the comparative coated carbide tools 1 to 10 all have a much larger 126 to 155 kg / mm 2.
^It showed a compressive residual stress in the range of ² .

[0011] Further, regarding the above-mentioned various coated carbide tools, work material: round bar with four longitudinal grooves at equal intervals in the longitudinal direction of Al-14% Si alloy, cutting speed: 700 m / min, depth of cut: 2 mm, feed : 0.3 mm / rev, Cutting time: 20 minutes, Wet high-speed intermittent cutting test of Al alloy was performed under the following conditions, and the flank wear width of the cutting edge was measured. Tables 1 and 2 show the measurement results.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

According to the results shown in Tables 1 and 2, the coated residual carbide tools 1 to 10 of the present invention have compressive residual stress of the thick artificial diamond coating layer formed by the thin vertical grooves formed on the local surface of the cutting edge. Because it has been significantly reduced, even if the intermittent cutting is performed at high speed, without occurrence of peeling in the thickened artificial diamond coating layer, while exhibiting excellent wear resistance for a long time, In the comparative coated carbide tools 1 to 10 in which the vertical fine grooves were not formed, the compression residual stress in the thickened artificial diamond coating layer was in a high state. It is evident that time will lead to a useful life. As described above, the coated cemented carbide tool of the present invention can be used not only for continuous cutting and intermittent cutting under normal conditions, but also for high-speed cutting, although the artificial diamond coating layer is in a thickened state. In this case, the thick artificial diamond coating layer exhibits excellent cutting performance over a long period of time without peeling.
Therefore, it is possible to satisfactorily cope with labor saving and labor saving in cutting.

[Brief description of the drawings]

FIG. 1 is a view showing a distribution state of vertical narrow grooves in a coated carbide tool.

Claims (1)

[Claims] 1. A surface-coated cemented carbide cutting tool comprising a cemented carbide substrate made of a tungsten carbide-based cemented carbide and a thick artificial diamond coating layer having an average layer thickness of 10 to 50 μm formed on the surface of the cemented carbide substrate. At least one of the cutting edge ridge line portion where the rake face and the flank intersect, the rake face, and the flank, at the local face of the cutting edge, １ ／ to の of the average layer thickness of the thickened artificial diamond coating layer. A thick artificial diamond coating layer formed by forming continuous and / or discontinuous laser cut notches having a depth within a range of 0.5 times over the entire local surface of the cutting blade. Surface coated cemented carbide cutting tool with peel resistance.