JP2001322004A - Surface coated cemented carbide cutting tool with excellent wear resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface coated cemented carbide cutting tool with excellent wear resistance. SOLUTION: In the surface coated cemented carbide cutting tool made by physically depositing a tough hard coating layer made of one kind of single layer or two kinds of multilayers of composite nitride and composite carbonitride of Ti and Al by average thickness of 0. 5 to 15 μm on the surface of a tool substrate made of tungsten carbide group cemented carbide or titanium carbonitride group cermet, an aluminum oxide main body layer made by substituting a part of Al by one kind or not less than two kinds of Ta, V, Nb, W, Mo and Cr of 5 to 20 atomic percent of the total amount with Al to bring a solid solution is physically deposited by average thickness of 0.5 to 15 μm as a wear resistant hard coating layer on the surface of the tool in a state that a crystal structure of aluminum oxide is held.

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 cemented carbide which has excellent wear resistance and therefore exhibits excellent cutting performance over a long period of time, for example, in continuous cutting and interrupted cutting of steel. Hereinafter, referred to as a coated carbide cutting tool).

[0002]

2. Description of the Related Art Conventionally, for example, an arc ion plating apparatus, which is a kind of physical vapor deposition apparatus schematically shown in FIG.
In the state heated to a temperature of ° C., an arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) on which a Ti-Al alloy having a predetermined composition is set, and at the same time, nitrogen gas as a reaction gas is introduced into the apparatus. Alternatively, nitrogen gas and methane gas are introduced, while tungsten carbide (hereinafter referred to as WC)
A tool base made of a base cemented carbide or a titanium cermet (hereinafter, referred to as TiCN) base cermet (hereinafter, collectively referred to as a cemented carbide tool base) is applied under a condition that a bias voltage of -120 V is applied, for example. As described in, for example, JP-A-62-56565, a composite nitride of Ti and Al [hereinafter, (Ti, A
1) N]] layer and composite carbonitride [hereinafter, (Ti,
Al) CN] coated superhard produced by physical vapor deposition of a tough hard coating layer consisting of one single layer or two or more layers of the above layers at an average layer thickness of 0.5 to 15 μm. Cutting tools are known.

[0003]

On the other hand, in recent years, FA and speed of cutting have been remarkable, and there is also a demand for labor saving and energy saving of cutting. As a result, the life of cutting tools has been extended. However, in the case of the above-mentioned conventional coated carbide cutting tool, the tough hard coating layer comprising the (Ti, Al) N layer and the (Ti, Al) CN layer has excellent strength. Although it has good toughness and good chipping resistance (the property that micro-chips are not likely to occur on the tool cutting edge), its wear life is not enough, so the service life can be reached in a relatively short time at present. is there.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
In view of the above, in order to improve the wear resistance of the conventional coated carbide cutting tool, a study was conducted by paying particular attention to the hard coating layer constituting the cutting tool. Al ₂ O ₃ layer as a normal hard coating layer is excellent in heat resistance and has high hardness, it is desirable to improve the wear resistance, but the Al ₂ O ₃ layer is (Ti, Al) N layer and (Ti, A) constituting the above-mentioned conventional coated carbide cutting tool
l) Since the adhesion to the CN layer is inferior, the coated carbide cutting tool obtained by forming the Al ₂ O ₃ layer on the surface of the conventional coated carbide cutting tool is particularly suitable for the tool cutting edge. When intermittent cutting with a high load is performed under heavy cutting conditions such as high depth of cut and high feed, the Al ₂ O ₃ layer is liable to peel off and cannot be put to practical use.

(B) When forming the Al ₂ O ₃ layer on the surface of the (Ti, Al) N layer and the (Ti, Al) CN layer constituting the above-mentioned conventional coated carbide cutting tool by physical vapor deposition. , Ta, V, N having an ion radius larger than that of Al
b, W, Mo and Cr, that is, an ionic radius of 0.5
For 7 Å of Al, Ta has an ion radius of 0.68 Å, Nb of 0.69 Å, V of 0.65 Å, W of 0.65 Å, and W of 0.68 Å, respectively.
Angstrom Mo and the 0.64 Å Cr, one or more of, Al ₂ O
_When a part of the Al atoms in the crystal structure of No. ₃ is substituted with 5 to 20 atomic%, preferably 7 to 15 atomic% in a proportion of the total amount with Al, the solid solution is contained. ₂ Al will always have the crystal structure with the O _{3 2} O ₃
Although the main layer has a compressive residual stress of 0.2 to 0.8 GPa, the ordinary physical vapor deposition Al ₂ O ₃ layer is affected by the layer thickness due to a remarkable increase in intra-lattice strain due to a large ion radius difference. On the other hand, the Al ₂ O ₃ main layer having a high compressive residual stress has a compressive residual stress of 1 to 2 GPa, and the (Ti, Al) N layer and the (Ti, Al) C
Since it adheres extremely strongly to the N layer and maintains the characteristics of Al ₂ O ₃ as it is, the (Ti, Al)
The surface of the N layer and the (Ti, Al) CN layer further includes
l ₂ O ₃ main layers of physical vapor deposition and formed by coating cemented carbide cutting tools, for example, the intermittent cutting of steel, even if especially in heavy cutting conditions such as high cut and high feed consuming high load on the tool cutting edge the The Al ₂ O ₃ main layer exhibits excellent wear resistance over a long period of time without peeling. (A)
The research results shown in (b) were obtained.

The present invention has been made based on the results of the above-mentioned research, and has the following features: (T)
one of the (i, Al) N layer and the (Ti, Al) CN layer
In a coated carbide cutting tool obtained by physical vapor deposition of a tough tough hard coating layer consisting of one kind of single layer or two kinds of multiple layers with an average layer thickness of 0.5 to 15 μm, the surface of the tough tough hard coating layer is
Further, as a wear-resistant hard coating layer, Ta, Nb, V, and W are 5 to 20 atomic% in a ratio of a part of Al to the total amount of Al while maintaining the crystal structure of Al ₂ O _3. , M
one or more substituted solid solution to become Al ₂ O ₃ based layer coating excellent in wear resistance formed by physical vapor deposition with an average layer thickness of 0.5~15μm carbide of o and Cr The cutting tool has features.

The reason why the average thickness of the tough hard coating layer is set to 0.5 to 15 μm in the coated carbide cutting tool of the present invention is that if the thickness is less than 0.5 μm, the hard coating layer has a desired thickness. The toughness cannot be ensured, and as a result chipping and chipping (small chipping) easily occur on the cutting edge. On the other hand, if the thickness of the layer exceeds 15 μm, thermoplastic deformation is caused by high heat generated during cutting and cutting. This is based on the reason that uneven wear occurs on the blade, and the wear progresses rapidly due to this, and the average layer thickness of the wear-resistant hard coating layer (Al ₂ O ₃ main layer) When the thickness is 0.5 to 15 μm, if the layer thickness is less than 0.5 μm, the desired wear resistance cannot be secured, while if the layer thickness exceeds 15 μm, chipping or chipping occurs in the cutting edge. Because it ’s easier.

[0008] Further, A in the wear-resistant hard coating layer
The substitution content of Ta, Nb, V, W, Mo and Cr was set to 5 to 20 atomic% because the content of
If the content is less than 20 at%, it is impossible to form a compressive residual stress capable of securing sufficient adhesion between the wear-resistant hard coating layer and the tough hard coating layer. %, The compressive residual stress becomes too large and self-destruction easily occurs. Further, a TiN layer having an average thickness of 0.1 to 2 μm may be formed on the abrasion-resistant hard coating layer, if necessary, since the TiN layer has a golden color tone. In this case, the layer thickness is 0.1 μm, because the color tone makes it easy to distinguish the cutting tool before and after use.
If it is less than m, the application of the color tone is insufficient, while the application of the color tone is sufficient with an average layer thickness of up to 2 μm.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated carbide cutting tool of the present invention will be specifically described with reference to examples. WC powder having an average particle diameter of 1 to 3 μm,
TiC powder, ZrC powder, VC powder, TaC powder, Nb
A C powder, a Cr ₃ C ₂ powder, a TiN powder, a TaN powder, and a Co powder were prepared, and these raw material powders were blended in the composition shown in Table 1, wet-mixed in a ball mill for 72 hours, and dried. It is press-molded into a green compact at a pressure of 1.5 × 10 ⁸ Pa, and the green compact is heated in a vacuum at a temperature of 1400 ° C.
For 1 hour, and after sintering, add R:
Honing process of 0.05 and ISO standard / SPG
Carbide tool bases A1 to A8 made of a WC-based cemented carbide having a chip shape of A120408 were formed. In addition, as raw material powders, T powder having an average particle size of 0.5 to 2 μm is used.
iCN (TiC / TiN = 50/50 by mass ratio) powder,
Mo ₂ C powder, ZrC powder, NbC powder, TaC powder,
WC powder, Co powder, and Ni powder were prepared, and these raw material powders were blended in the composition shown in Table 2, wet-mixed in a ball mill for 24 hours, and dried, and then 9.8 × 10
^A green compact is press-molded at a pressure of ⁷ Pa, and the green compact is pressed in a nitrogen atmosphere of 1.3 × 10 ³ Pa at a temperature of 1540 ° C.
For 1 hour, and after sintering, add R:
Applying honing process of 0.03, ISO standard, CNM
Carbide tool bases B1 to B6 made of TiCN-based cermet having a chip shape of G120406 were formed.

[0010] Then, the carbide tool bases A1 to A8 and B1 to B6 are ultrasonically cleaned in acetone and dried, and each is charged into an arc ion plating apparatus shown in FIG. Ti-Al alloys with various component compositions are installed as electrodes (evaporation sources),
While the inside of the apparatus was evacuated and kept at a vacuum of 1.3 × 10 ⁻³ Pa, the inside of the apparatus was heated to 500 ° C. with a heater.
A gas was introduced into the apparatus to make an Ar atmosphere of 2.5 Pa,
In this state, a pulse bias voltage of -800 V is applied to the cemented carbide substrate to wash the surface of the cemented carbide substrate with Ar gas bombardment. Then, nitrogen gas or a mixture of nitrogen gas and methane gas is introduced into the apparatus as a reaction gas. And a pulsed bias voltage applied to the cemented carbide tool base was reduced to -200 V to generate an arc discharge between the cathode electrode and the anode electrode. Conventionally coated super hard tool substrates 1 to 22 were produced by forming a tough hard coating layer having the target composition and target layer thickness shown in Tables 3 and 4 on the respective surfaces of A8 and B1 to B6.

Next, the conventional coated carbide cutting tools 1 to 1
The arc ion pump of FIG.
Using a cathode electrode (evaporation source) with a rating device
And one of Ta, Nb, V, W, Mo and Cr
Or Al- (Ta, Nb,
(V, W, Mo, Cr) alloy and exhaust the inside of the device
3 × 10^-3While maintaining the vacuum of Pa, the device with the heater
Was heated to a predetermined temperature in the range of 620 to 720 ° C.
In this state, the pulse bias voltage applied to the carbide substrate is -7.
00 V, and then oxygen gas as a reaction gas in the apparatus.
While introducing, between the cathode electrode and the anode electrode
To generate an arc discharge, and the target composition and
Al of target layer thickness_TwoO_ThreeWear-resistant hard coating consisting of main layer
By forming a layer, the coated carbide cutting tool of the present invention 1-2
2 were each manufactured. The above-mentioned coated carbide cutting tool 1 of the present invention
Constituting the wear-resistant hard coating layer of No. 22 to No. 22_TwoO _ThreeMain layer
Of Ta, Nb, V, W, Mo and Cr in
Is quantitatively analyzed using an energy dispersive X-ray analyzer.
As a result, the content was substantially the same as the target content in Table 5.
And the Al_TwoO_ThreeX-ray response to compressive residual stress of main layer
When measured using the force measurement method, the results shown in Table 5 were obtained.
showed that. Furthermore, the composition and thickness of various coating layers
Also measured by Auger spectroscopy and light microscopy
At this time, it is substantially the same as the target composition and target layer thickness in Tables 3 to 5.
Shows the same composition and average layer thickness (average value of measurements at five arbitrary locations)
did.

Next, among the various coated carbide cutting tools obtained as a result, the coated carbide cutting tools 1 to 16 of the present invention and the conventional coated carbide cutting tools 1 to 16 are described below. Work material: JIS SNCM439 Round bar with four longitudinal grooves at equal intervals in the length direction, Cutting speed: 300 m / min., Feeding: 0.3 mm / rev., Depth of cut: 2.6 mm, Cutting time: 10 min. Intermittent high-cut cutting test, and work material: JIS S50C, longitudinally spaced round bar with four longitudinal grooves, cutting speed: 280 m / min., Feed: 0.4 mm / rev., Depth of cut: 1. 5mm, cutting time: 10 minutes, dry intermittent high feed cutting test of carbon steel under the following conditions:
Also, for the coated carbide cutting tools 17 to 22 of the present invention and the conventional coated carbide cutting tools 17 to 22, a work material: JIS S30C, a longitudinally-elongated round bar with four longitudinal grooves, a cutting speed: 380 m / min., feed: 0.3 mm / rev., depth of cut: 2.6 mm, cutting time: 10 minutes, dry intermittent high depth of cut feed cutting test of carbon steel, and work material: length of JIS SNCM439 Round bar with 4 vertical grooves at equal intervals in the length direction, Cutting speed: 350 m / min., Feed: 0.42 mm / rev., Depth of cut: 1.5 mm, Cutting time: 10 min. Perform high-feed cutting test,
In each cutting test, the flank wear width of the cutting edge was measured.
Table 6 shows the measurement results.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

[0016]

[Table 4]

[0017]

[Table 5]

[0018]

[Table 6]

[0019]

According to the results shown in Tables 3 to 6, in the coated carbide cutting tools 1 to 22 of the present invention, the Al ₂ O ₃ main layer constituting the wear-resistant hard coating layer is smaller than that of Al. It substitutes and contains one or more of Ta, V, Nb, W, Mo, and Cr having a large ionic radius, thereby maintaining a remarkably high compressive residual stress to constitute a tough hard coating layer ( Ti, Al) N layer and (Ti, Al) CN
Since it comes to adhere firmly to the layer, even if intermittent cutting of steel is performed under high cutting and high feed heavy cutting conditions, the Al ₂ O ₃ main layer does not peel and excellent wear resistance is obtained. In contrast to conventional coated carbide cutting tools 1-22
It is evident that the wear progresses rapidly under the severe conditions as described above due to insufficient wear resistance of the tough hard coating layer. As described above, the coated cemented carbide cutting tool according to the present invention provides an abrasion-resistant hard coating layer comprising Al ₂ O
_{(3) Due to the} excellent wear resistance and adhesion of the main layer, continuous cutting and intermittent cutting of various steels under normal conditions, as well as intermittent cutting under extremely severe cutting conditions, with high cutting and high feed weights The above A
l ₂ O ₃ in the main layer without occurrence of peeling, and no chipping or chipping occurs the cutting edge, it showed excellent wear resistance, which exhibits a superior cutting performance over a long period of time, the cutting It can respond satisfactorily to energy saving and labor saving.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of an arc ion plating apparatus.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C23C 14/08 C23C 14/08 A

Claims (1)

[Claims] 1. A tool base comprising a tungsten carbide based cemented carbide or a titanium carbonitride based cermet,
Physically vapor-depositing a tough hard coating layer composed of one single layer or two or more multiple layers of a composite nitride layer of Ti and Al and a composite carbonitride layer with an average layer thickness of 0.5 to 15 μm. In a cutting tool made of a surface-coated cemented carbide, the surface of the tough hard coating layer is further treated as A wear-resistant hard coating layer while retaining the crystal structure of aluminum oxide.
5 to 20 atomic% in a proportion of l to the total amount with Al
Characterized in that an aluminum oxide-based layer obtained by substituting and solid-dissolving one or more of Ta, V, Nb, W, Mo and Cr is physically vapor-deposited with an average layer thickness of 0.5 to 15 μm. Surface-coated cemented carbide cutting tools with excellent wear resistance.