JP2003127020A - Square endmill made of coated cemented carbide with peripheral cutting edge having superior chipping- resistance in high-speed cutting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a square endmill made of coated cemented carbide with cutting edges having superior chipping-resistance in high-speed cutting. SOLUTION: A cylindrical blind hole is formed on the bottom surface of the hard metal body longitudinally and coaxially. A cylindrical tip made of a heavy tungsten-base cemented carbide is fit into the cylindrical blind hole. The hard metal body of cutting edges is constituted by sintered compact-powder of; Co: 8-10 wt.%, chromium carbide and/or vanadium carbide: 0.1-1.5 wt.%, if necessary composite carbide of Ta and Nb: 0.1-1.5 wt.%, and tungsten carbide: remainder. The cylindrical tip is constituted by sintered compressed-powder of; Co: 0.5-2 wt.% and tungsten carbide: remainder. The diameter of the cylindrical tip will be equivalent to 25-45% of the peripheral cutting edge diameter, and the length to 20-40% of the length of cutting edges.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated cemented carbide square end mill (hereinafter referred to as a coated cemented carbide end mill) which exhibits excellent chipping resistance of an outer peripheral blade particularly in high-speed cutting. .

[0002]

2. Description of the Related Art Conventionally, a coated carbide end mill has been generally used for surface machining, groove machining, shoulder machining, etc. of a work material such as steel or cast iron.
It has a shape consisting of a cutting edge portion having a bottom blade and an outer peripheral edge, and a shank portion, and at least the cutting edge portion is contained in Co contained in a proportion of 4 to 16 mass% as a binder phase forming component. Cr and / or solid solution containing 0.1 to 3 mass%
Or, by the grain growth suppressing effect of the V component, the grain size of tungsten carbide (hereinafter, referred to as WC) as a hard phase forming component is set to an average grain size of desirably 0.7 μm or less to form a fine grain structure, which is further required. Accordingly, for the purpose of substantially forming a dispersed phase to improve the high temperature hardness and thereby further improve the wear resistance, a composite carbide of Ta and Nb [hereinafter, (Ta,
Nb) C]] on the surface of the cemented carbide substrate containing 0.1 to 1.5% by mass of the composition formula: (Ti _1-X Al _X ) N, (Ti _1-X Al _X) ) C
_1-m N _m , the same [Ti _{1- (X + Y )} Al _x Si _Y ] N, and the same [Ti _{1- (X + Y)} Al _x Si _Y ] C _1-m N _m ,
By the measurement by the Auger spectroscopic analyzer in the central part in the thickness direction,
In atomic ratio, X: 0.35 to 0.70, Y: 0.01 to
Ti and A satisfying 0.10 and m: 0.50 to 0.99
a compound nitride [hereinafter, represented by (Ti, Al) N] layer of 1;
Composite carbonitride of Ti and Al [hereinafter, (Ti, Al) CN
Layer], a composite nitride of Ti, Al, and Si [hereinafter,
(Ti, Al, Si) N] layer, and Ti and Al
And Si compound carbonitride [hereinafter, (Ti, Al, Si) C
[N]] A coated carbide end mill formed by vapor deposition of a hard coating layer comprising any one of the layers or two or more types of multilayers and having an average layer thickness of 0.5 to 7 μm. It has been known.

[0003]

On the other hand, in recent years, there is a strong demand for labor saving, energy saving, and cost reduction of the cutting process, and along with this, along with the high performance of the cutting device, the cutting process is Although it tends to be performed at high speed, in the above-mentioned conventional coated carbide end mill, when this is used for high-speed cutting, rotational vibration shake occurs in the end mill itself,
This rotational vibration shake increases as the cutting speed (rotation speed) increases, and as a result, the outer peripheral blade in particular receives a high-pitch mechanical impact, so the outer peripheral blade is prone to chipping, and therefore the end mill is The current situation is that the chip life (fine chipping) generated on the peripheral edge reaches the end of its useful life in a relatively short time.

[0004]

Therefore, the present inventors have
From the above viewpoint, in order to develop a coated carbide end mill that can prevent the occurrence of rotational vibration shake in high-speed cutting,
In particular, as a result of conducting research by paying attention to the above conventional coated carbide end mill, at least the cutting edge portion, that is, the cutting edge portion (in this case, the shank portion has a joining structure composed of high-speed steel) or the cutting edge portion. Replace the cemented carbide substrate of the shank with C
o: 8 to 10% by mass, chromium carbide (hereinafter referred to as Cr ₃ C ₂ ) and / or vanadium carbide (hereinafter referred to as VC): 0.1 to 1.5% by mass, and if necessary (Ta ，
Nb) C, preferably expressed by the composition formula: (Ta _1-X Nb _X ) C, X: 0.1 to 0.4 is satisfied (Ta, N
b) C: 0.1 to 1.5% by mass, WC: the balance, a sintered compact of a green compact (density: about 14.6 g
/ Cm ³ ), and as shown in the schematic side view (a), schematic front view (bottom blade surface side) (b), and schematic longitudinal sectional view (c) of FIG. A cylindrical notched bottomed hole is formed concentrically along the lengthwise direction of the cutting blade on the bottom blade surface of the cemented carbide substrate of the blade portion, and Co: 0.5 to 2 is provided in this cylindrical notched bottom hole. Mass%, WC: balance, sintered compact of green compact (density: about 15.6 g /
cm ³ ), the diameter of the cylindrical tip is 25 to 45% of the outer diameter of the outer peripheral blade of the cutting edge portion, and the same length is obtained as a result of repeated experiments. Is 20% to 40% of the length of the cutting edge portion, and in the coated carbide end mill obtained as a result, the cylindrical cutting bottomed hole of the bottom blade surface of the cutting edge portion is Due to the relatively heavy cylindrical tip attached, the occurrence of rotational vibration shake is significantly suppressed even at high speed cutting, thereby preventing the occurrence of chipping of the outer peripheral blade and achieving excellent cutting performance for a long period of time. I got the result of the research.

The present invention has been made based on the above-mentioned research results, and is composed of a cutting edge portion and a shank portion, and at least the cutting edge portion is formed on the surface of the cemented carbide substrate by the composition formula: (Ti _1-X Al _X ) N, the same (Ti _1-X Al _X ) C
_1-m N _m , the same [Ti _{1- (X + Y )} Al _x Si _Y ] N, and the same [Ti _{1- (X + Y)} Al _x Si _Y ] C _1-m N _m ,
By the measurement by the Auger spectroscopic analyzer in the central part in the thickness direction,
In atomic ratio, X: 0.35 to 0.70, Y: 0.01 to
0.10, m: 0.50 to 0.99 are satisfied (Ti,
Al) N layer, (Ti, Al) CN layer, (Ti, Al, S
i) A hard coating layer comprising an N layer and a single layer of any one of (Ti, Al, Si) CN layers, or a multilayer of two or more kinds, and having an average layer thickness of 0.5 to 7 μm. In a coated cemented carbide end mill formed by vapor deposition, a cylindrical cutting bottomed hole exists concentrically along the length direction of the cutting edge portion on the bottom edge surface of the cemented carbide substrate of the cutting edge portion, The cut-out bottomed hole has a structure in which a cylindrical tip made of a relatively heavy cemented carbide is fitted, and the main body of the cemented carbide substrate of the cutting edge portion is made of Co: 8- 10% by mass, Cr ₃ C ₂ and / or VC: 0.1 to 1.5% by mass, optionally (Ta, Nb) C: 0.1 to 1.5% by mass, WC: balance. It is a sintered compact of a green compact having a blending composition, and the above cylindrical tip has a blending composition comprising Co: 0.5 to 2 mass% and WC: the rest. And the diameter of the cylindrical tip is 25 to 45% of the outer diameter of the outer peripheral blade of the cutting blade portion, and the same length is 20 to 4 of the length of the cutting blade portion.
It is characterized by a coated cemented carbide end mill that exhibits excellent chipping resistance in the outer peripheral blade in high-speed cutting, which has dimensions corresponding to 0%.

The reasons why the coated carbide end mill of the present invention is numerically limited as described above will be described below. (A) Co content of the cemented carbide base body of the cutting edge The Co component has the effect of improving the sinterability and forming a binder phase to improve the strength of the cemented carbide base body.
If the proportion is less than 8% by mass, the desired strength required for the cemented carbide base body cannot be secured, and the density difference with the cylindrical tip collapses, and rotational vibration shake easily occurs.
On the other hand, when the proportion exceeds 10 mass%, the wear resistance is rapidly softened and the progress of wear is promoted. Therefore, the proportion is set to 8 to 10 mass%.

(B) Cr of the cemented carbide base body of the cutting edge
₃ C ₂ and VC content These components significantly suppress the growth of WC that forms a hard phase in the state of solid solution in Co that forms a binder phase during sintering, and changes the WC particle size to the average particle size. And preferably 0.7μ
There is an effect of forming a fine grain structure of m or less, but this effect becomes insufficient when the ratio of Cr ₃ C ₂ and VC is less than 0.1% by mass, and when the ratio exceeds 1.5% by mass, The binder phase which is solid-dissolved is hardened and causes chipping, so the proportion thereof is set to 0.1 to 1.5% by mass.

(C) (T of the cemented carbide base body of the cutting edge portion)
The a, Nb) C content (Ta, Nb) C component has a function of substantially forming a dispersed phase to improve high-temperature hardness, and thus contributes to further improvement of wear resistance. However, if the proportion is less than 0.1% by mass, the desired improving effect on the above-mentioned action cannot be obtained, and if the proportion exceeds 1.5% by mass, chipping tends to occur. The ratio was set to 0.1 to 1.5% by mass.

(D) Co Content of Cemented Carbide of Cylindrical Tip Cylindrical tip does not require strength, but 0.5% by mass or more is required for forming a sintered body, while the ratio is 2% by mass.
When the value exceeds 0.5, the density difference from the main body of the cemented carbide substrate collapses, and rotational vibration shake easily occurs, so the ratio is 0.5.
Was determined to be 2% by mass.

(D) Dimension of Cylindrical Tip The dimension of the cylindrical tip is empirically determined as described above, and therefore, the diameter and the length of the tip may be above or below the above range. Since the balance of the density difference between the hard alloy base body and the main body of the hard alloy base is lost and rotational vibration shake occurs, its diameter is set to 25
.About.45%, and the same length was defined as a dimension corresponding to 20 to 40% of the length of the cutting edge portion.

(E) Composition of hard coating layer and average layer thickness (Ti, Al) N layer, (Ti, Al) CN layer, (Ti,
Al in the Al, Si) N layer and the (Ti, Al, Si) CN layer is a solid solution for increasing the high temperature hardness and heat resistance of the layer and thus improving wear resistance,
Therefore, the composition formula: (Ti _1-X Al _X ) N, the same (Ti _1-X Al _X ) N
Al _X ) C _1-m N _m , the same [Ti _{1- (X + Y)} Al _X Si _Y ] N, and the same [Ti _{1- (X + Y)} Al _X Si _Y ] C _1-m N _m If the X value is less than 0.35, the desired effect of improving the high temperature hardness and heat resistance cannot be obtained. On the other hand, if the value exceeds 0.70,
The X value is set to 0.35 to 0.70 (atomic ratio) for the reason that chipping is likely to occur in the hard coating layer. Further, the (Ti, Al, Si) N layer and the (T
Si in the (i, Al, Si) CN layer has an effect of further improving the heat resistance of the layer, but if the Y value of the above composition formula is less than 0.01, the desired heat resistance improving effect cannot be obtained. If the value exceeds 0.10, chipping of the hard coating layer is likely to occur, so that the Y value is 0.01 to 0.01.
It was set to 0.10 (atomic ratio). Furthermore, (Ti, Al)
Since the C component in the CN layer and the (Ti, Al, Si) CN layer has a function of further improving hardness, (T
The i, Al) CN layer and the (Ti, Al, Si) CN layer are the (Ti, Al) N layer and the (Ti, Al,
Si) N layer has a relatively high hardness, but in this case the ratio of the C component is less than 0.01, that is, the m value is 0.
If it exceeds 99, the predetermined hardness improving effect cannot be obtained, while C
The ratio of the components exceeds 0.50, that is, the m value is 0.5.
If it is less than this, the toughness will drop sharply, so the m value was set to 0.50 to 0.99. Further, in this case, if the average layer thickness is less than 0.5 μm, the above-mentioned characteristics possessed by it cannot be sufficiently exhibited, while if the average layer thickness exceeds 7 μm, chipping occurs in the hard coating layer. Therefore, the average layer thickness is set to 0.5 to 7 μm.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the coated carbide end mill of the present invention will be specifically described by way of Examples. As the raw material powder, WC powder, Cr ₃ C ₂ powder, VC powder, and Co powder each having a predetermined average particle size within the range of 0.1 to ₃ μm, and (Ta, Nb) C [TaC / NbC =
A mass ratio of 80/20] powder was prepared, and these raw material powders were compounded in the compounding composition shown in Table 1 and the results were measured by a ball mill.
Mixed powder a-1 to a-1 for forming a main body of a cemented carbide substrate including a cutting edge portion and a shank portion after wet mixing for 2 hours and drying.
4 and cylindrical tip forming mixed powders b-1 to b-4 were prepared, and then 75
Extrusion press molding with a pressure of MPa into a compact for forming a main body of a cemented carbide substrate having a predetermined dimension (diameter and length) and a compact for forming a cylindrical tip (both are round bar shapes),
First, among the green compacts, the green compact for forming a cylindrical tip is placed under a vacuum of 1.3 Pa in a nitrogen atmosphere at a temperature of 135.
Sintering is performed by sintering at a predetermined temperature within a range of 0 to 1480 ° C. for 1 hour, while the body forming green compact is heated to a temperature of 600 ° C. in a reduced pressure nitrogen atmosphere of 100 Pa. In the state of degreasing under the condition of holding for 1 hour, a cylindrical notched bottomed hole having a size corresponding to the size of the cylindrical tip was concentrically formed on the cutting edge surface forming surface, and Table 2 The sintered body of the cylindrical tip is bonded by the combination shown in, and in this state, the sintered body is sintered under the same conditions as the sintering conditions of the sintered body of the cylindrical tip, and finally ground. By processing, the cemented carbide bases A1 to A14 of the present invention each having the size and shape shown in Table 2 were manufactured.

For the purpose of comparison, as shown in Table 3, except that the above-mentioned cylindrical notched bottomed hole is not formed, and therefore the cylindrical tip is not attached to the cylindrical notched bottomed hole. The above-mentioned cemented carbide substrate A1 to A1 of the present invention
Comparative Cemented Carbide Substrates B1 to B1 under the same manufacturing conditions as in No. 4
4 were each manufactured.

Then, these cemented carbide substrates A1 to A14
And B1 to B14 were ultrasonically cleaned in acetone and dried, and then charged into the arc ion plating apparatus shown in FIG. 2, respectively, while the cathode electrode (evaporation source) had various component compositions. After mounting the Ti-Al alloy and the Ti-Al-Si alloy respectively, and heating the inside of the apparatus to 500 ° C. with a heater while exhausting the inside of the apparatus and maintaining a vacuum of 0.5 Pa, Ar gas was introduced into the apparatus. And an Ar atmosphere of 10 Pa is introduced, and in this state, a bias voltage of −800 V is applied to the cemented carbide substrate to clean the surface of the cemented carbide substrate by Ar gas bombardment, and then the inside of the apparatus is 1.3 × 10 ^−3. While maintaining the vacuum of Pa while heating the inside of the device to a predetermined temperature within the range of 600 to 700 ° C. with a heater, nitrogen gas or nitrogen gas and methane gas as reaction gas in the device. The mixed gas was introduced with a reactive atmosphere of 6 Pa, lowering the bias voltage applied to the carbide substrate to -200 V, the cathode electrode (Ti
-Al alloy or Ti-Al-Si alloy) and an anode electrode to generate an arc discharge, so that the target composition and the target layer thickness shown in Tables 4 and 5 are formed on the respective surfaces of the cemented carbide substrate. By forming the hard coating layer, the coated carbide end mills 1 to 14 of the present invention and the comparative coated carbide end mills 1 to 14 were manufactured.

Regarding the hard coating layers of the coated end mills 1 to 14 of the present invention and the comparative coated cemented carbide end mills 1 to 14 obtained as a result, the compositions of the respective central portions in the thickness direction of the constituent layers are analyzed by an Auger spectroscopic analyzer. And the thickness of the constituent layers of the hard coating layer were measured by a cross section using a scanning electron microscope, and both showed substantially the same values as the target composition and the target layer thickness.

Next, for each of the above coated carbide end mills, a JI having a width of 400 mm as a work material
Using S / SKD11 (hardness: HRC60) plate material, high-speed shoulder milling was performed under the conditions shown in Tables 6 and 7, and the flank wear width of the outer peripheral blade of the cutting edge portion is shown in Tables 6 and 7, respectively. The cutting length up to the value used as a guideline was measured. The results of these measurements are shown in Tables 6 and 7 as average values.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

[Table 4]

[0021]

[Table 5]

[0022]

[Table 6]

[0023]

[Table 7]

[0024]

From the results shown in Tables 1 to 7, all of the coated carbide end mills 1 to 14 of the present invention can be used for high speed cutting due to the relatively heavy cylindrical tip attached to the tip of the cutting edge. Since the rotational vibration shake of itself is remarkably suppressed, chipping of the outer peripheral blade is eliminated and excellent wear resistance is exhibited, while the cylindrical coated comparative end mills 1- In No. 14, it is apparent that rotational vibration shake occurs in high-speed cutting, chipping easily occurs on the outer peripheral blade due to this, and the service life is reached in a relatively short time. As described above, the coated carbide end mill of the present invention exhibits excellent chipping resistance of the outer peripheral blade not only for cutting under normal conditions but also for high-speed cutting, and has excellent cutting performance over a long period of time. Therefore, it is possible to satisfactorily deal with labor saving and energy saving of the cutting process and further cost reduction.

[Brief description of drawings]

1A is a schematic side view illustrating a coated carbide end mill of the present invention, FIG. 1B is a schematic front view thereof, and FIG. 1C is a schematic longitudinal sectional view thereof.

FIG. 2 is a schematic explanatory view of an arc ion plating device.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiyuki Taniuchi             1511 Furumagi, Ishishita-cho, Yuki-gun, Ibaraki Prefecture             Mitsubishi Materials Corporation Tsukuba Works F-term (reference) 3C022 KK03

Claims (2)

[Claims] 1. A composition comprising a cutting edge portion and a shank portion, wherein at least the cutting edge portion is formed on a surface of a cemented carbide base made of a tungsten carbide based cemented carbide, a composition formula: (Ti _1-X Al _X ). N, same (Ti _1-X Al _X ) C
_1-m N _m , the same [Ti _{1- (X + Y )} Al _x Si _Y ] N, and the same [Ti _{1- (X + Y)} Al _x Si _Y ] C _1-m N _m ,
By the measurement by the Auger spectroscopic analyzer in the central part in the thickness direction,
In atomic ratio, X: 0.35 to 0.70, Y: 0.01 to
Ti and A satisfying 0.10 and m: 0.50 to 0.99
l composite nitride layer, Ti and Al composite carbonitride layer, Ti
And a composite nitride layer of Al and Si, and Ti, Al and Si
Of the composite carbonitride layer described above, or a surface-coated cemented carbide formed by vapor deposition forming a hard coating layer having a mean layer thickness of 0.5 to 7 μm, the hard coating layer being composed of two or more kinds of multiple layers. In an alloy square end mill, a cylindrical cutting bottomed hole exists concentrically in the bottom blade surface of the cemented carbide substrate of the cutting edge portion along the length direction of the cutting blade portion, and the cylindrical cutting bottomed hole Has a structure in which a cylindrical tip made of a relatively heavy tungsten carbide-based cemented carbide is fitted, and the main body of the cemented carbide substrate of the cutting edge portion is made of Co: 8 to 10% by mass. , Chromium carbide and / or vanadium carbide: 0.1
1.5% by mass, tungsten carbide: balance, a sintered compact of a powder compact having a compounding composition of the above cylindrical tip, Co: 0.5 to 2% by mass, tungsten carbide: balance, It is composed of a sintered compact of a green compact having a composition, and the diameter of the cylindrical tip is 25 times the outer diameter of the outer peripheral blade of the cutting edge portion.
~ 45%, and the same length was set to a dimension corresponding to 20 to 40% of the length of the cutting edge portion, respectively, the outer peripheral blade exhibits excellent chipping resistance in the high-speed cutting process. Hard alloy square end mill. 2. A composition consisting of a cutting edge portion and a shank portion, at least the cutting edge portion being formed on a surface of a cemented carbide base made of a tungsten carbide based cemented carbide, a composition formula: (Ti _1-X Al _X ). N, same (Ti _1-X Al _X ) C
_1-m N _m , the same [Ti _{1- (X + Y )} Al _x Si _Y ] N, and the same [Ti _{1- (X + Y)} Al _x Si _Y ] C _1-m N _m ,
By the measurement by the Auger spectroscopic analyzer in the central part in the thickness direction,
In atomic ratio, X: 0.35 to 0.70, Y: 0.01 to
Ti and A satisfying 0.10 and m: 0.50 to 0.99
l composite nitride layer, Ti and Al composite carbonitride layer, Ti
And a composite nitride layer of Al and Si, and Ti, Al and Si
Of the composite carbonitride layer described above, or a surface-coated cemented carbide formed by vapor deposition of a hard coating layer composed of two or more types of multilayers and having an average layer thickness of 0.5 to 7 μm. In an alloy square end mill, a cylindrical cutting bottomed hole exists concentrically in the bottom blade surface of the cemented carbide substrate of the cutting edge portion along the length direction of the cutting blade portion, and the cylindrical cutting bottomed hole Has a structure in which a cylindrical tip made of a relatively heavy tungsten carbide-based cemented carbide is fitted, and the main body of the cemented carbide base body of the cutting edge portion is made of Co: 8 to 10% by mass. , Chromium carbide and / or vanadium carbide: 0.1
1.5 mass%, composite carbide of Ta and Nb: 0.1 to 1.5 mass%, tungsten carbide: balance, a sintered compact of a powder compact having the following composition: : 0.5 to 2% by mass, tungsten carbide: balance, and a sintered compact of a powder compact having a composition of: and the diameter of the cylindrical tip is 25 times the outer diameter of the outer peripheral blade of the cutting edge portion.
~ 45%, and the same length was set to a dimension corresponding to 20 to 40% of the length of the cutting edge portion, respectively, the outer peripheral blade exhibits excellent chipping resistance in high-speed cutting processing. Hard alloy square end mill.