JP2003205404A - Surface-coated cemented carbide cutting tool capable of demonstrating excellent wear resistance when cutting hardly machinable material at high speed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cemented carbide cutting tool capable of demonstrating excellent wear resistance when cutting a hardly machinable material at a high speed. <P>SOLUTION: In this surface-coated cemented carbide cutting tool, an oxidation resistant coated layer which has a mean layer thickness of 2-12 μm, satisfies the composition formula (Al<SB>1-(</SB>V<SB>+</SB>W<SB>)</SB>TiVSiW)N (where, V is 0.10-0.25, and W is 0.05-0.20 in terms of atom ratio), and consists of an Al-based composite nitride layer having a cubic crystalline structure physically vapor-deposited on a surface of a tungsten carbide-based cemented carbide base body or carbo-nitride titanium cermet base body via a crystalline history layer which has a mean layer thickness of 0.05-1 μm, satisfies the composition formula (Al<SB>1-(</SB>X<SB>+</SB>Y<SB>)</SB>TiXSiY)N (where, X is 0.35-0.60, and Y is 0.01-0.15 in terms of atom ratio), and consists of an Al-Ti composite nitride layer similarly having the cubic crystalline structure. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxidation-resistant coating layer having excellent high-temperature characteristics, and particularly to a difficult-to-cut material such as stainless steel or mild steel which generates high heat. The present invention relates to a surface-coated cemented carbide cutting tool that exhibits excellent wear resistance when used in high-speed cutting (hereinafter, referred to as a coated cemented carbide tool). 2. Description of the Related Art Generally, a cutting tool includes a throw-away tip which is removably attached to a tip of a cutting tool for turning or planing of a work material such as steel or cast iron. There are drills and miniature drills used for drilling and cutting work materials, and solid type end mills used for face milling, grooving, shoulder processing, etc. of the work material. A throw-away end mill tool or the like which is freely mounted and performs cutting in the same manner as the solid type end mill is known. In recent years, tungsten carbide (hereinafter referred to as W
C) based cemented carbide or titanium carbonitride (hereinafter referred to as Ti
The composition formula: (Al) is formed on the surface of a substrate made of a base cermet (indicated by CN)
_{1- (V + W) Ti V} Si W) N ( provided that an atomic ratio, V is 0.
Al-based composite nitride satisfying 10 to 0.25 and W represents 0.05 to 0.20 [hereinafter referred to as (Al-ti-si)
N)], a coated carbide tool formed by physical vapor deposition of an oxidation-resistant coating layer having an average layer thickness of 2 to 12 μm, which is particularly suitable for cutting difficult-to-cut materials such as stainless steel and mild steel. It is attracting attention. [0004] Further, the above coated super hard tool is prepared by charging the above super hard substrate into an arc ion plating apparatus which is a kind of physical vapor deposition apparatus schematically shown in FIG. The atmosphere is, for example, 1.3 × 10 ^−3.
In a state of heating to a temperature of 500 ° C. as a vacuum of Pa,
An arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) on which an Al-ti-si alloy having a predetermined composition is set, for example, under the conditions of a voltage: 35 V and a current: 90 A, and simultaneously reacts in the apparatus. Nitrogen gas was introduced as a gas, while the cemented carbide substrate was applied to the surface of the cemented carbide substrate under the condition that a bias voltage of, for example, -200 V was applied.
It is also known to be manufactured by depositing an oxidation-resistant coating layer consisting of the (Al-ti-si) N layer. [0005] In recent years, the performance of cutting equipment has been remarkably improved, and on the other hand, there has been a strong demand for labor saving, energy saving, and further cost reduction in the cutting work. Although there is a tendency to increase the speed, in the above-mentioned conventional coated carbide tools, there is no problem in the cutting of difficult-to-cut materials such as stainless steel and mild steel under normal conditions, but this is When the cutting of the work material is performed under high-speed cutting conditions with extremely high heat generation, since the oxidation-resistant coating layer does not have sufficient high-temperature characteristics,
At present, the progress of abrasion of the cutting blade is remarkably accelerated, and as a result, the service life of the cutting blade is relatively short. Means for Solving the Problems Accordingly, the present inventors have proposed:
From the viewpoints described above, even when cutting hard-to-cut materials such as stainless steel and mild steel under high-speed cutting conditions, in order to develop a coated carbide tool that demonstrates excellent wear resistance, in particular, the above-mentioned The inventors focused on the oxidation-resistant coating layer that forms the conventional coated carbide tool, and as a result of conducting research, (a) the oxidation resistance of the (Al-ti-si) N layer that forms the above-described conventional coated carbide tool The coating layer has a “hexagonal” crystal structure. Before forming the “hexagonal” oxidation-resistant coating layer on the surface of the superhard substrate by physical vapor deposition, the composition formula: (Al _{1− ( X + Y)} Ti _X
Si _Y ) N (where X is 0.35 to 0.6 in atomic ratio)
0 and Y represent 0.01 to 0.15), and as a result, an Al—Ti-based composite nitride [hereinafter referred to as (Al, Ti-si) N When a layer is formed by vapor deposition with an extremely thin average layer thickness of 0.05 to 1 μm, the above-mentioned (Al-ti-si) physically deposited thereon and having an originally “hexagonal” crystal structure is formed. ) The N layer also has the same “cubic” crystal structure as its crystal structure due to the crystal hysteresis effect of the (Al, Ti-si) N layer. (B) (Al-t) having a “cubic” crystal structure
The i-si) N layer has the same “hexagonal” (Al-ti-s)
i) High temperature characteristics (high temperature oxidation resistance, high temperature strength,
And high-temperature hardness), so that the oxidation-resistant coating layer composed of a (cubic) (Al-ti-si) N layer is physically vapor-deposited on the surface of the super-hard substrate. The tool must exhibit excellent wear resistance in high-speed cutting of difficult-to-cut materials such as stainless steel and mild steel with high heat generation. 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 cemented carbide substrate of 0.05 to 1%.
having an average layer thickness of μm and a composition formula: (Al _{1− (X + Y)}
Ti _X Si _Y ) N (where X is 0.35
0.60, Y represents 0.01 to 0.15) and has a cubic crystal structure (Al, Ti-s
i) having an average layer thickness of 2 to 12 μm via a crystal history layer composed of an N layer, and having a composition formula: (Al _{1− (V + W)} Ti _V S
i _W ) N (where V is 0.10 to 0.2 in atomic ratio)
5, W represents 0.05 to 0.20) and also has a cubic crystal structure (Al-ti-s
i) physical oxidation of an oxidation-resistant coating layer composed of an N layer,
It is characterized by a coated carbide tool that exhibits excellent wear resistance in high-speed cutting of difficult-to-cut materials. Next, the reason why the composition and the average thickness of the crystal hysteresis layer and the oxidation-resistant coating layer constituting the coated carbide tool of the present invention are limited as described above will be described. (A) Crystal history layer [(Al, Ti-si) N layer] (A
The Ti in the l, Ti-si) N layer is included for the purpose of making the crystal structure of the layer “cubic”, and therefore, the ratio of Ti to the total amount of Al and Si (atomic ratio; If the ratio is less than 0.35, a cubic crystal structure cannot be secured, while if the ratio exceeds 0.60, the high-temperature hardness and heat resistance of the layer itself tend to decrease. From 0.35 to 0.60
It was decided. Similarly, Si is contained for the purpose of improving the hardness of the layer, but if the ratio is less than 0.01 in the total amount of Al and Ti, the desired effect of improving the hardness cannot be obtained. If it exceeds 0.15, it becomes difficult to maintain the crystal structure of the layer in “cubic”, so the ratio was set to 0.01 to 0.15. When the average layer thickness is less than 0.05 μm, the crystal history effect of converting the originally “hexagonal” crystal structure of the (Al-ti-si) N layer to “cubic” can be sufficiently exerted. On the other hand, since the crystal hysteresis effect requires an average layer thickness of up to 1 μm, the average layer thickness is determined to be 0.05 to 1 μm. (B) Oxidation resistant coating layer [(Al-ti-s
i) N layer] (Al-ti-si) The ti of the N layer is included for the purpose of improving the strength of the AlN layer having excellent oxidation resistance, and the proportion of the ti in the total amount of Al and Si. If the ratio is less than 0.10, the desired strength-improving effect cannot be obtained. On the other hand, if the ratio exceeds 0.25, the oxidation resistance of the layer is sharply reduced, and wear during cutting accompanied by high heat generation is accelerated. Therefore, the ratio was set to 0.10 to 0.25. Similarly, Si is contained for the purpose of improving the hardness of the layer, but the content is 0.1% in the total amount of Al and Ti.
If it is less than 0.05, the desired hardness improving effect cannot be obtained, while if its proportion exceeds 0.20, the proportion of Al becomes relatively too small and the oxidation resistance rapidly decreases. , And the ratio was determined to be 0.05 to 0.20.
If the average layer thickness is less than 2 μm, the desired wear resistance cannot be secured, while the average layer thickness is 12 μm
If the average thickness exceeds 2 mm, chipping is likely to occur on the cutting edge. Therefore, the average layer thickness is set to 2 to 12 μm. Next, the coated carbide tool of the present invention will be specifically described with reference to examples. (Example 1) As raw material powders, WC powder, TiC powder, ZrC powder, V
C powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, T
An iN powder, a TaN powder, and a Co powder were prepared, and these raw material powders were blended in the blending composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and then dried.
a into a green compact at the pressure of a
sintering in a vacuum at a temperature of 1400 ° C. for 1 hour, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.05 to form a WC having a chip shape of ISO standard CNMG120408. Substrates A1 to A10 made of base cemented carbide
Was formed. In addition, as raw material powders,
TiCN having an average particle size of 2 μm (by weight ratio TiC /
(TiN = 50/50) 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 into the composition shown in Table 2. After wet-mixing with a ball mill for 24 hours and drying, the mixture is pressed into a green compact at a pressure of 100 MPa, and the green compact is heated in a nitrogen atmosphere of 2 kPa at a temperature of:
Sintered under the condition of holding at 1500 ° C. for 1 hour, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.03 to obtain a TiC having a chip shape conforming to ISO standard, CNMG120408.
Carbide substrates B1 to B6 made of N-based cermet were formed. Next, these super-hard substrates A1 to A10 and B1 to B6 are ultrasonically cleaned in acetone and dried, and each is charged into a usual arc ion plating apparatus illustrated in FIG. On the other hand, the cathode electrode (evaporation source) has various component compositions (Al, Ti-s
i) After mounting the alloy and the (Al-ti-si) alloy, evacuating the inside of the apparatus and keeping the apparatus at a vacuum of 1.3 × 10 ⁻³ Pa, the inside of the apparatus was heated to 500 ° C. with a heater, and then Ar was heated. A gas was introduced into the apparatus to form an Ar atmosphere of 10 Pa, and under this condition, a bias voltage of -800 V was applied to the superhard substrate to clean the surface of the superhard substrate by Ar gas bombardment. To a reaction atmosphere of 6 Pa, and a bias voltage applied to the cemented carbide substrate is reduced to -200 V to generate an arc discharge between the cathode electrode and the anode electrode. To each surface of ~ A10 and B1 ~ B6,
By depositing a crystal hysteresis layer [(Al, Ti-si) N layer] and an oxidation-resistant coating layer [(Al-ti-si) N layer] having the target composition and target layer thickness shown in Tables 3 and 4. ,
FIG. 2 (a) is a schematic perspective view, and FIG. 2 (b) is a throw-away tip made of a surface-coated cemented carbide alloy of the present invention as a coated carbide tool of the present invention having a shape shown in a schematic longitudinal sectional view (hereinafter, the present invention) 1 to 20). For the purpose of comparison, as shown in Tables 5 and 6, the conventional surface as a conventional coated carbide tool was obtained under the same conditions except that the crystal hysteresis layer [(Al, Ti-si) N layer] was not formed. Coated cemented carbide throw-away tips (hereinafter referred to as conventional coated cemented carbide tips) 1 to 20 were produced, respectively. Next, the coated carbide tips 1-2 of the present invention
0 and conventional coated carbide tips 1 to 20 were screwed to the tip of a tool steel tool with a fixing jig. Work material: JIS 304 stainless steel round bar, Cutting speed: 200 m / min . Infeed: 2 mm Feed: 0.21 mm / rev. , Cutting time: 8 minutes, Dry high-speed continuous turning test of stainless steel under the following conditions: Work material: JIS SUS304, four longitudinal grooves at equal intervals in the longitudinal direction, Cutting speed: 180 m / min. Infeed: 0.1 mm Feed: 0.17 mm / rev. , Cutting time: 2 minutes, Dry high-speed intermittent turning test of stainless steel under the following conditions:
Further, a work material: a round bar with four longitudinal grooves at equal intervals in the longitudinal direction of JIS S15C, a cutting speed: 300 m / min. Infeed: 2 mm Feed: 0.3 mm / rev. A dry high-speed intermittent turning test of mild steel was performed under the following conditions: cutting time: 3 minutes, and the flank wear width of the cutting edge was measured in each turning test. The measurement results are shown in Tables 7 and 8. [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] [Table 6] [Table 7] [Table 8] Example 2 As raw material powder, average particle size:
Medium coarse WC powder having 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, 1.2 μm
NbC powder, 1.2 μm ZrC powder, 2.3 μm
m Cr ₃ C ₂ powder, 1.5 μm VC powder, 1.0
μm of (Ti, W) C powder and 1.8 μm of Co
Powders were prepared, and each of these raw material powders was blended into the blending composition shown in Table 9, further added with wax, and ball-mixed in acetone for 24 hours, and dried under reduced pressure.
Press molding at a pressure of 0 MPa into various green compacts of a predetermined shape, and pressing these green compacts in a vacuum atmosphere of 6 Pa at 7 ° C. /
The temperature was raised to a predetermined temperature in the range of 1370 to 1470 ° C. at a heating rate of 1 minute, kept at this temperature for 1 hour, and then sintered under the condition of furnace cooling to obtain a sample having a diameter of 8 mm, 13 mm, and 26 mm. Kinds of round bar sintered bodies for forming a cemented carbide substrate are formed, and the above three kinds of round bar sintered bodies are subjected to grinding processing in a combination shown in Table 9 to obtain a diameter x length of a cutting edge portion. Is 6mm × 1 each
3mm, 10mm x 22mm, and 20mm x 45m
Carbide substrates (end mills) a to h having a size of m were manufactured, respectively. Next, these super-hard substrates (end mills)
a to h were ultrasonically cleaned in acetone, dried and charged in a usual arc ion plating apparatus also illustrated in FIG. 1 under the same conditions as in Example 1 above.
A crystal hysteresis layer having a target composition and a target layer thickness shown in Table 10 on each surface of the carbide substrates a to h [(A
l, Ti-si) N layer] and an oxidation-resistant coating layer [(Al
-Ti-si) N layer] to obtain FIG.
(A) is a schematic front view, and (b) is an end mill made of a surface-coated cemented carbide of the present invention as a coated carbide tool of the present invention having a shape shown by a schematic cross-sectional view of a cutting edge portion (hereinafter, the present invention). (Referred to as coated carbide end mills) 1 to 8 respectively.
For the purpose of comparison, as shown in Table 11, under the same conditions except that the above-mentioned crystal hysteresis layer [(Al, Ti-si) N layer] was not formed, the conventional surface-coated ultra-hard tool as the conventional coated carbide tool was used. Hard metal end mills (hereinafter referred to as conventional coated carbide end mills) 1 to 8 were manufactured, respectively. Next, the coated carbide end mill 1 of the present invention will be described.
-8 and the conventional coated carbide end mills 1-8, the coated carbide end mills 1-3 of the present invention and the conventional coated carbide end mills 1-3 are: work material: plane dimension: 100 mm × 250 mm, thickness: 5
0 mm JIS SUS304 plate, Cutting speed: 35 m / min. , Groove depth (cut): 2.5 mm, Table feed: 130 mm / min, Wet high-speed groove cutting test of stainless steel (using water-soluble cutting oil) under the following conditions: coated carbide end mills 4 to 6 of the present invention and For the conventional coated carbide end mills 4 to 6, work material: plane dimension: 100 mm x 250 mm, thickness: 5
0 mm JIS S15C plate, Cutting speed: 100 m / min. , Groove depth (cut): 4 mm, Table feed: 450 mm / min, Dry high-speed groove cutting test of mild steel, coated carbide end mills 7 and 8 of the present invention and conventional coated carbide end mills 7 and 8 , Work material: Plane dimensions: 100 mm x 250 mm, thickness: 5
0 mm JIS SUS304 plate, Cutting speed: 30 m / min. , Groove depth (cut): 8 mm, Table feed: 110 mm / min, Wet stainless steel high-speed groove cutting test (using water-soluble cutting oil) under the following conditions: The cutting groove length was measured until the diameter of the tip surface of the blade portion decreased by 0.2 mm, which is a standard for the service life. The measurement results are shown in Tables 10 and 11, respectively. [Table 9] [Table 10] [Table 11] (Example 3) The diameters of 8 mm (for forming the super-hard substrates a to c), 13 mm (for forming the super-hard substrates d to f), and 26 mm (for the super-hard substrate g) produced in Example 2 described above. h
(For forming), the diameter x length of the groove forming portion was 4 mm x 13 mm (carbide substrate a ') by grinding from the three types of round rod sintered bodies. ~ C '), 8mm
× 22 mm (carbide substrate d ′ to f ′) and 16 mm ×
Carbide substrates (drills) a 'to h' each having a size of 45 mm (carbide substrates g 'and h') were manufactured. Next, these super hard substrates (drills) a '
~ H 'was ultrasonically cleaned in acetone, dried and charged in a usual arc ion plating apparatus also illustrated in FIG. 1 under the same conditions as in Example 1 above.
A crystal hysteresis layer [(Al, Ti-si) N layer] and an oxidation resistant coating layer [((Al, Ti-si) N layer] having target compositions and target layer thicknesses shown in Table 12 on the respective surfaces of the cemented carbide substrates a 'to h'. Al-ti-si) N layer],
FIG. 4 (a) is a schematic front view, and FIG. 4 (b) is a surface-coated cemented carbide drill (hereinafter, referred to as a coated cemented carbide tool) having the shape shown in the schematic cross-sectional view of the groove forming portion. Conventional coated carbide drills) 1 to 8 were manufactured respectively. For the purpose of comparison, as shown in Table 13, under the same conditions except that the above-mentioned crystal hysteresis layer [(Al, Ti-si) N layer] was not formed, the conventional surface-coated super-hard tool as the conventional coated carbide tool was used. Drills made of hard alloy (hereinafter referred to as conventional coated carbide drills) 1 to 8 were manufactured, respectively. Next, the above-described coated carbide drills 1 to 8 of the present invention will be described.
Of the coated carbide drills 1 to 8 of the present invention, the coated carbide drills 1 to 3 of the present invention and the coated carbide drills 1 to 3 of the present invention are: work material: plane dimension: 100 mm × 250 mm, thickness: 8
mm JIS SUS304 plate material, Cutting speed: 30 m / min. , Feed: 0.08 mm / rev, Wet high-speed drilling test of stainless steel under the following conditions: coated carbide drills 4 to 6 of the present invention and conventional coated carbide drills 4 to 6 : 100 mm x 250 mm, thickness: 1
6 mm JIS SUS304 plate, Cutting speed: 30 m / min. , Feed: 0.15 mm / rev, Wet high-speed drilling cutting test of stainless steel under the following conditions: For coated carbide drills 7 and 8 of the present invention and conventional coated carbide drills 7 and 8, work material: plane dimensions : 100mm x 250mm, thickness: 3
2 mm JIS S15C plate material, Cutting speed: 80 m / min. , Feed: 0.30 mm / rev, Wet high-speed drilling and cutting test of mild steel under the following conditions: In any wet high-speed drilling and cutting test (using water-soluble cutting oil), flank wear of the cutting edge at the tip 0.3 width
The number of drilling processes up to mm was measured. The measurement results are shown in Tables 12 and 13, respectively. [Table 12] [Table 13] The coated carbide tips 1-20, coated end mills 1-8, and coated drill 1 of the present invention as the coated carbide tools of the present invention obtained as a result.
To 8 (Hi, Si-N) layer and oxidation resistant coating layer ((Al-ti-si) N layer), and the conventional coated carbide tips 1 to 4 as the conventional coated carbide tool. 2
0, high-temperature oxidation-resistant coating layers of conventional coated carbide end mills 1 to 8 and conventional coated carbide drills 1 to 8 [(Al-ti-
si) N layer], the center in the thickness direction was measured using an Auger spectroscopic analyzer. As a result, each of the compositions showed substantially the same composition as the target composition. Further, when the thickness of the above-described constituent layers of the coated carbide tool of the present invention and the conventional coated carbide tool was measured in cross section using a scanning electron microscope, the average layer thickness was substantially the same as the target layer thickness. Thick (5
(Average value of point measurements). Tables 3 to 6 and Tables 10 to 13 show the results of cross-sectional measurement of the crystal structure of the above-described constituent layers of the coated carbide tool of the present invention and the conventional coated carbide tool using a transmission electron microscope. . From the results shown in Tables 3 to 13, the oxidation-resistant coating layer has a cubic crystal structure due to the interposition of the crystal hysteresis layer, and has excellent high-temperature characteristics (high-temperature oxidation resistance). , High-temperature strength, and high-temperature hardness), the coated carbide tools of the present invention exhibit excellent wear resistance even when cutting stainless steel or mild steel at high speed with high heat generation. On the other hand, in conventional coated carbide tools with a hexagonal crystal structure of the oxidation-resistant coating layer, it is clear that the wear progresses quickly due to lack of high-temperature characteristics, and the service life is relatively short. is there. As described above, the coated cemented carbide tool of the present invention exhibits excellent wear resistance even in high-speed cutting of difficult-to-cut materials such as stainless steel and mild steel, which have a particularly high viscosity and generate high heat, for a long time. Since it shows excellent cutting performance, it is possible to sufficiently satisfactorily cope with high performance of the cutting device, labor saving and energy saving of the cutting process, and further cost reduction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic explanatory view of an arc ion plating apparatus. FIG. 2A is a schematic perspective view of a coated carbide tip, and FIG.
1 is a schematic vertical sectional view of a coated carbide tip. FIG. 3 (a) is a schematic front view of a coated carbide end mill,
(B) is a schematic transverse sectional view of the cutting blade portion. FIG. 4A is a schematic front view of a coated carbide drill, and FIG.
FIG. 3 is a schematic cross-sectional view of the groove forming portion.

Continuation of front page    (72) Inventor Yusuke Tanaka             179 Kanegasaki Nishi-Oike, Uozumi Town, Akashi City, Hyogo Prefecture             1. MMC Kobelcourt Co., Ltd.             Inside F-term (reference) 3C037 CC02 CC04 CC09 CC11                 3C046 FF03 FF05 FF10 FF13 FF16                       FF19 FF25                 4K029 AA04 BA58 BB02 BB07 BC02                       BD05 EA01

Claims (1)

Claims: 1. A surface of a tungsten carbide-based cemented carbide substrate or a titanium carbonitride-based cermet substrate, having an average layer thickness of 0.05 to 1 μm, and a composition formula: (Al _{1 - (X + Y) Ti X} Si Y) N ( provided that an atomic ratio, X is from .35 to 0.60, Y 0.01 to 0.1
5), has an average layer thickness of 2 to 12 μm via a crystal history layer composed of an Al—Ti-based composite nitride layer having a cubic crystal structure, and has a composition formula: ( Al _{1- (V + W)} Ti _V Si _W ) N (where V is 0.10 to 0.25 and W is 0.05 to 0.2 in atomic ratio)
0), and excellent wear resistance in high-speed cutting of difficult-to-cut materials formed by physical vapor deposition of an oxidation-resistant coating layer composed of an Al-based composite nitride layer also having a cubic crystal structure. A surface-coated cemented carbide cutting tool that shows off.