JP4510323B2 - Surface-coated cemented carbide cutting drill with excellent wear resistance in high-speed cutting - Google Patents

Description

【００２０】
【表２】

【００２１】
【表３】

【００２２】
【表４】

【００２３】
【発明の効果】
表１〜４に示される結果から、本発明被覆超硬ドリル１〜５は、いずれも超硬基体がすぐれた高温硬さを有することから、硬質被覆層の具備するすぐれた高温硬さと相俟って、鋼の穴あけ切削加工を高い発熱を伴う高速で行っても、すぐれた耐摩耗性を示し、長期に亘ってすぐれた切削性能を発揮するのに対して、比較被覆超硬ドリル１〜１２に見られる通り超硬基体の配合成分である（Ｗ，Ｔｉ）Ｃの組成、さらに前記（Ｗ，Ｔｉ）ＣおよびＮｂＣの配合割合のうちの少なくともいずれかがこの発明の範囲から低い方に外れると、十分な高温硬さが得られないことから、摩耗進行が速く、一方反対に高い方に外れると、切刃部に欠けやチッピングが発生し、いずれの場合も比較的短時間で使用寿命に至ることが明らかである。
上述のように、この発明の被覆超硬ドリルは、各種の鋼や鋳鉄などの通常の条件での切削加工は勿論のこと、特に高速穴あけ切削加工においてもすぐれた耐摩耗性を発揮し、使用寿命の延命化を可能にするものであるから、穴あけ切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。
【図面の簡単な説明】
【図１】 （ａ）は被覆超硬ドリルの概略正面図で、（ｂ）は同溝形成部の概略横断面図である。
【図２】 アークイオンプレーティング装置の概略説明図である。[0001]
BACKGROUND OF THE INVENTION
The present invention is used for high-speed cutting of steel, cast iron, etc., which has a high-temperature hardness of a substrate made of a tungsten carbide-based cemented carbide (hereinafter referred to as a cemented carbide substrate) and thus has high heat generation. The present invention relates to a surface-coated cemented carbide cutting drill (hereinafter referred to as a coated carbide drill) that exhibits excellent wear resistance.
[0002]
[Prior art]
Conventionally, in general, a coated carbide drill has, for example, a schematic front view in FIG. 1A and a schematic cross-sectional view of a groove forming portion in FIG. It is used for drilling and cutting work materials.
Further, as the above-described coated carbide drill, a hard coating layer composed of a composite nitride of Ti and Al [hereinafter referred to as (Ti, Al) N] is formed on the surface of the cemented carbide substrate with an average layer of 0.5 to 6 μm. A coated carbide drill formed with a thickness is also known.
[0003]
Further, an arc ion plating apparatus in which the (Ti, Al) N layer, which is a hard coating layer of the above-described conventional coated carbide drill, is a kind of physical vapor deposition apparatus schematically shown in FIG. 2, for example, Between the anode electrode and the cathode electrode (evaporation source) in which a Ti—Al alloy having a predetermined composition is set in a state where the inside of the apparatus is heated to a temperature of 500 ° C. with, for example, a vacuum of 0.5 Pa. In addition, for example, arc discharge is generated under the conditions of voltage: 35 V and current: 90 A, and simultaneously, nitrogen gas is introduced into the apparatus as a reaction gas, while a bias voltage of −200 V, for example, is applied to the carbide substrate. It is also known that it is formed.
[0004]
[Problems to be solved by the invention]
On the other hand, there are strong demands for labor saving, energy saving, and cost reduction for cutting such as drilling in recent years, and with this, cutting tends to increase in speed with the high performance of cutting machines. However, in the above conventional coated carbide drill, there is no problem when it is used for drilling cutting under normal conditions such as steel or cast iron. Due to the high heat generated during processing, the high-temperature hardness of the tip part including the cutting edge surface and the thin part (cutting edge part) of the groove forming part is significantly reduced, and as a result, the progress of wear is significantly accelerated. Therefore, the service life is reached in a relatively short time.
[0005]
[Means for Solving the Problems]
Therefore, the present inventors have focused on the above-described conventional coated carbide drill from the above viewpoint, and as a result of conducting research to make the carbide substrate constituting this excellent high-temperature hardness,
(A) As a raw material powder, tungsten carbide (hereinafter referred to as WC) powder, composition formula: (W _1-Y Ti _Y ) C (wherein Y represents 0.3 to 0.5 in atomic ratio) Using W and Ti composite carbide [hereinafter referred to as (W, Ti) C] powder, niobium carbide (hereinafter referred to as NbC) powder, and Co powder, the composition was expressed in mass% (hereinafter referred to as%). Indicates mass%),
Co: 8-10%
(W, Ti) C: 23 ~30%,
NbC: 5 to 7 %,
WC: The rest
When the cemented carbide substrate is composed of a sintered compact of green compact as follows, the cemented carbide substrate is composed of W and Ti having excellent high-temperature hardness together with the WC phase as a dispersed phase. And Nb composite carbide (hereinafter referred to as (W, Ti, Nb) C) phase coexist and the binder phase forms a dispersed phase into Co during sintering. Since it has a structure composed of a Co—W alloy that dissolves and thereby has excellent high temperature strength, it has excellent high temperature hardness.
[0006]
(B) A composition formula: (Ti _1-X Al _X ) N (where X is an atomic ratio) using an arc ion plating apparatus as a hard coating layer on the surface of the superhard substrate of (a) above. When a (Ti, Al) N layer having 0.1 to 0.6) is formed, the high-temperature hardness is further improved.
[0007]
(C) Therefore, the coated carbide drill formed by vapor-depositing the hard coating layer of (b) on the surface of the superhard substrate of (a) is provided with excellent high-temperature hardness. Even if this is used for high-speed drilling with high heat generation, the progress of wear is remarkably suppressed, and excellent wear resistance is exhibited over a long period of time.
The research results shown in (a) to (c) above were obtained.
[0008]
This invention was made based on the above research results,
Co: 8-10%
(W, Ti) C having a composition formula: (W _1-Y Ti _Y ) C (wherein Y represents 0.3 to 0.5 in atomic ratio): 23 to 30%,
NbC: 5 to 7 %
WC: The rest
A sintered compact of a green compact having a composition composed of the following, and by a structure observation with a scanning electron microscope, the dispersed phase is composed of a WC phase and a (W, Ti, Nb) C phase, and the binder phase is By using an arc ion plating apparatus as a hard coating layer on the surface of a carbide substrate having a structure made of a Co-W alloy,
Average layer thickness having a composition formula: (Ti _1-X Al _X ) N (wherein X is 0.1 to 0.6 by atomic ratio): (Ti, Al) N layer of 1 to 6 μm,
It is characterized by a coated carbide drill that is formed by vapor deposition and exhibits excellent wear resistance in high-speed cutting.
[0009]
Next, in the coated carbide drill of the present invention, the compounding composition of the cemented carbide substrate (sintered body), the X value of the hard coating layer, and the average layer thickness of the hard coating layer are limited as described above. Explain why.
(1) Composition of carbide substrate (a) Co
The Co component has an effect of improving the sinterability and improving the room temperature strength of the sintered body. However, if the blending ratio is less than 8%, a desired improvement effect cannot be obtained in the above-described operation, while If the blending ratio exceeds 10%, it becomes easy to cause thermoplastic deformation that causes uneven wear during high-speed cutting. As a result, the progress of wear is promoted, so the blending ratio is set to 8 to 10%. It was.
[0010]
(B) (W, Ti) C
(W, Ti) C combines with NbC during sintering to form (W, Ti, Nb) C having high high-temperature hardness, and this exists as a dispersed phase to increase the high-temperature hardness of the carbide substrate. Although it has the effect of significantly improving, if the blending ratio is less than 23% , the effect of improving the high temperature hardness by the (W, Ti, Nb) C phase cannot be sufficiently secured, while the blending ratio is 30%. it exceeds the, present as dispersed phase (W, Ti, Nb) too the proportion of C phase is large, since the chipping or chipping the cutting edge portion (small chipping) tends to occur, the blending ratio 23 ~ 30%.
In addition, the Ti component of (W, Ti) C has an effect of promoting the bonding of (W, Ti) C with NbC during sintering so that the NbC phase does not exist as a dispersed phase. The proportion (Y value) is the proportion of the total amount with the W component, and if the atomic ratio is less than 0.3, the desired effect cannot be obtained in the above action, and the (W, Ti, Nb) C phase formed further. However, if the ratio (Y value) exceeds 0.5 , the strength of the (W, Ti, Nb) C phase itself formed after sintering is reduced. Since a tendency appears and it becomes easy for chipping and chipping to occur at the cutting edge due to this, the ratio (Y value) was determined to be 0.3 to 0.5 in terms of atomic ratio.
[0011]
(C) NbC
NbC combines with (W, Ti) C during sintering as described above to form a (W, Ti, Nb) C phase, thereby significantly improving the high-temperature hardness of the cemented carbide substrate. If the blending ratio is less than 5%, sufficient high-temperature hardness cannot be secured in the formed (W, Ti, Nb) C phase, while if the blending ratio exceeds 7% , (W, Ti, Nb) The proportion of the Nb component in the Ti, Nb) C phase becomes excessive, and a tendency to decrease in its own strength appears, and this causes the chip edge portion to be easily chipped and chipped. The percentage was set at 5-7 % .
[0012]
(2) X value of the hard coating layer Al in the (Ti, Al) N layer gives heat resistance to TiN having a high room temperature strength and dissolves in order to have excellent high temperature hardness. Therefore, if the X value of the composition formula: (Ti _1-X Al _X ) N is less than 0.1 in atomic ratio, the desired excellent high-temperature hardness cannot be secured, while the value is the same as 0. If it exceeds .6, chipping and chipping are likely to occur in the cutting edge, so the X value was determined to be 0.1 to 0.6 in terms of atomic ratio.
[0013]
(3) constituting the average layer thickness hard layer of the hard coating layer (Ti, Al) the average layer thickness of the N layer, 1 was a ~6μm, in an average layer thickness of less than 1 [mu] m, hard layer This is because the desired high-temperature hardness cannot be stably imparted to the surface, and on the other hand, if the average layer thickness exceeds 6 μm, chipping and chipping are likely to occur on the cutting edge surface.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated carbide drill of the present invention will be specifically described with reference to examples.
As the raw material powder, WC powder having an average particle diameter of 3.0 μm, (W _0.7 Ti _0.4 ) C powder of 1.8 μm, (W _0.5 Ti _0.5 ) C powder of 1.9 μm, 2.0 μm ( W _0.4 Ti _0.6 ) C powder, 1.2 μm NbC powder, and 1.8 μm Co powder are prepared, and the required raw material powders of these raw material powders are blended in the composition shown in Table 1, respectively. Further, wax was added and mixed in a ball mill for 24 hours in acetone, dried under reduced pressure, and then pressed into various green compacts having a predetermined shape at a pressure of 100 MPa. These green compacts were placed in a 6 Pa vacuum atmosphere. The temperature is increased to a predetermined temperature within a range of 1370 to 1470 ° C. at a temperature increase rate of 7 ° C./min, held at this temperature for 1 hour, sintered under furnace cooling conditions, and having a diameter of 8 mm, 13 mm, and Sintered round bars for forming three types of 26 mm carbide substrates Further, from the above-mentioned three kinds of round bar sintered bodies, the diameters and lengths of the groove forming portions are 6 mm × 13 mm, 10 mm × 22 mm, and 20 mm in the combinations shown in Table 1 by grinding. Carbide substrates a, b, g, h, and i having dimensions of 45 mm were manufactured, respectively.
[0015]
Next, these superhard substrates a, b, g, h, i are ultrasonically cleaned in acetone and dried, and each is loaded into a normal arc ion plating apparatus illustrated in FIG. On the other hand, a Ti-Al alloy having various component compositions was attached as a cathode electrode (evaporation source), and the inside of the apparatus was heated to 500 ° C. with a heater while evacuating the apparatus and maintaining a vacuum of 0.5 Pa. Then, Ar gas is introduced into the apparatus to form an Ar atmosphere of 10 Pa. 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 with Ar gas bombardment, and then as a reaction gas in the apparatus. Nitrogen gas was introduced to make a reaction atmosphere of 6 Pa, and the bias voltage applied to the cemented carbide substrate was lowered to −200 V to generate an arc discharge between the cathode electrode and the anode electrode. The cemented carbide substrate a, b, g, h, on the respective surfaces of the i, to form the target composition shown in Table 3 (X value) and the target layer thickness of (Ti, Al) N layer as a hard coating layer Te Thus, the coated carbide drills 1 to 5 of the present invention having the shape shown in the schematic front view of FIG. 1A and the schematic cross-sectional view of the groove forming portion in FIG.
[0016]
For the purpose of comparison, as shown in Table 2 of the carbide substrate A'～l ', relates to the composition of the cemented carbide substrate, it affects the high-temperature hardness (W, Ti) composition and C, further wherein ( Comparative coated cemented carbide drills 1-12 as shown in Table 4 under the same conditions except that at least one of the blending ratios of W, Ti) C and NbC is a blending composition that is out of the scope of the present invention. Were manufactured respectively.
[0017]
In addition, about the present invention coated carbide drills 1 to 5 and comparative coated carbide drills 1 to 12, the structure of the carbide substrate was observed using a scanning electron microscope and an Auger spectroscopic analyzer. , (W, Ti, Nb) shows a structure composed of a dispersed phase of C phase and a binder phase of a Co—W alloy, and the composition (measured in the center in the thickness direction) and thickness ( When the cross-section measurement) was measured, all showed substantially the same values as the target composition and the target layer thickness.
[0018]
Next, among the present invention coated carbide drills 1 to 5 and the comparative coated carbide drills 1 to 12, the present invention coated carbide drills 1 and 2 and the comparative coated carbide drills 1 to 4,
Work material: Plane dimensions of 100 mm × 250, JIS / SCM440 plate material having a thickness of 50 mm,
Cutting speed: 140 m / min,
Feed: 0.2mm / rev,
About the wet high-speed drilling test of alloy steel under the conditions of the present invention, the present invention coated carbide drills 3 and 4 and the comparative coated carbide drills 5-8,
Work material: Plane dimensions of 100 mm × 250, JIS / SCM440 plate material having a thickness of 50 mm,
Cutting speed: 150 m / min,
Feed: 0.25mm / rev,
For the wet high speed drilling test of alloy steel under the conditions of the present invention, the coated carbide drill 5 of the present invention and the comparative coated carbide drills 9-12,
Work material: Plane dimensions of 100 mm × 250, JIS / SCM440 plate material having a thickness of 50 mm,
Cutting speed: 160 m / min,
Feed: 0.3mm / rev,
Wet high speed drilling test of alloy steel under the conditions of
In each wet (using water-soluble cutting oil) high-speed drilling test, the number of drilling processes until the flank wear width of the cutting edge surface reached 0.3 mm was measured. The measurement results are shown in Tables 3 and 4, respectively.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
[Table 3]

[0022]
[Table 4]

[0023]
【The invention's effect】
From the results shown in Tables 1 to 4, since the coated carbide drills 1 to 5 of the present invention all have a high temperature hardness with which the cemented carbide substrate is excellent, it is compatible with the excellent high temperature hardness of the hard coating layer. Therefore, even if the drilling of steel is performed at high speed with high heat generation, it exhibits excellent wear resistance and exhibits excellent cutting performance over a long period of time. As shown in FIG. 12, at least one of the composition of (W, Ti) C, which is a blending component of the carbide substrate, and the blending ratio of (W, Ti) C and NbC is lower from the scope of the present invention. If removed, sufficient high-temperature hardness cannot be obtained, so wear progresses rapidly.On the other hand, if it is removed higher, chipping or chipping occurs in the cutting edge, and in any case, it can be used in a relatively short time. It is clear that it reaches the end of its life.
As described above, the coated carbide drill of the present invention exhibits excellent wear resistance not only in cutting processing under normal conditions such as various steels and cast iron, but also in high-speed drilling processing. Since the service life can be extended, it is possible to satisfactorily cope with labor saving and energy saving of drilling and cost reduction.
[Brief description of the drawings]
1A is a schematic front view of a coated carbide drill, and FIG. 1B is a schematic cross-sectional view of the groove forming portion.
FIG. 2 is a schematic explanatory diagram of an arc ion plating apparatus.

Claims (1)

% By mass
Co: 8-10%
Compound carbide of W and Ti having a composition formula: (W _1-Y Ti _Y ) C (wherein Y represents 0.3 to 0.5 in atomic ratio): 23 to 30%,
Niobium carbide: 5-7%,
Tungsten carbide: the rest,
A sintered compact of a green compact having a composition composed of: a dispersed phase is composed of a tungsten carbide phase and a composite carbide phase of W, Ti, and Nb, and a bonded phase by a structure observation by a scanning electron microscope Using an arc ion plating apparatus as a hard coating layer on the surface of a substrate composed of a tungsten carbide base cemented carbide having a structure made of a Co-W alloy,
Average layer thickness having a composition formula: (Ti _1-X Al _X ) N (wherein X represents 0.1 to 0.6 in atomic ratio): 1 to 6 μm of a composite nitride layer of Ti and Al,
Made by depositing form, surface-coated cemented carbide cutting drill exhibits wear resistance excellent in high-speed cutting.

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