JP4716006B2 - Surface coated high speed tool steel gear cutting tool with excellent wear resistance with hard coating layer in high speed gear cutting of alloy steel - Google Patents

Description

  In the present invention, the hard coating layer has excellent heat resistance, and also has high-temperature hardness and high-temperature strength. Therefore, particularly when used for high-speed gear cutting with high heat generation such as alloy steel, The present invention relates to a surface-coated high-speed tool steel gear cutting tool (hereinafter referred to as a coated high-speed gear cutting tool) that exhibits excellent wear resistance.

  Conventionally, in general, various gears are used as structural members of automobiles, aircrafts, and various driving devices. For gear cutting of the gear teeth of these gears, a solid hob (for example, see the schematic perspective view of FIG. 3) or a pinion cutter (for example, FIG. 4), and further, a cutting tool such as a shaving cutter is used.

In order to improve the wear resistance of the tool, a hard coating layer is usually provided on the surface of the tool. However, for a gear cutting tool, for example, a high machined shape shown in FIGS. 3 and 4 is used. A coated high-speed gear cutting tool is known in which a gear cutting tool body made of high-speed tool steel is used as a base, and a hard coating layer with excellent wear resistance is provided on the surface of the base. , for example, a composition _{formula: [Ti 1- (X + Y} ) Al X Si Y] N ( provided that an atomic ratio, X is 0.50 to 0.75, Y represents a 0.01-0.10)

It is known that a hard coating layer composed of a composite nitride of Ti, Al, and Si [hereinafter referred to as (Ti, Al, Si) N] satisfying the above conditions is formed by vapor deposition with a thickness of 0.1 to 20 μm. Furthermore, the (Ti, Al, Si) N layer constituting the hard coating layer has the characteristics that the high temperature hardness is increased by Al as a constituent component, the high temperature strength is increased by the Ti, and the heat resistance is further improved by the Si. It is also known that

Furthermore, the coated high-speed gear cutting tool provided with the hard coating layer is applied to the above-mentioned base (high-speed gear cutting tool main body), for example, an arc ion plating apparatus which is a kind of physical vapor deposition apparatus schematically shown in FIG. ) Between the anode electrode and the cathode electrode (evaporation source) in which a Ti—Al—Si alloy having a predetermined composition is set while the inside of the apparatus is heated to a temperature of, for example, 400 ° C. with a heater. For example, arc discharge was generated under the condition of current: 90 A, and nitrogen gas was introduced into the apparatus at the same time as a reaction gas to obtain a reaction atmosphere of, for example, 2 Pa, while a bias voltage of, for example, −100 V was applied to the substrate. It is also known that a hard coating layer composed of the (Ti, Al, Si) N layer is deposited on the surface of the substrate under conditions.
Japanese Patent No. 2793773

  In recent years, the performance of cutting devices has been dramatically improved. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and with this, cutting tends to be faster. For coated gear cutting tools, there is no problem when used under normal gear cutting conditions, but when this is used under high speed gear cutting conditions such as alloy steel with high heat generation, it is particularly hard. Due to the lack of heat resistance of the coating layer, the progress of wear is promoted, so that the service life is reached in a relatively short time.

In view of the above, the present inventors have developed the above-described conventional coating tool to develop a coated high-speed gear cutting tool exhibiting excellent wear resistance with a hard coating layer particularly in high-speed gear cutting of alloy steel. As a result of conducting research by focusing on the (Ti, Al, Si) N layer that constitutes the hard coating layer of high-speed gear cutting tools,
(A) In the (Ti, Al, Si) N layer constituting the hard coating layer, the heat resistance is improved if the content ratio of the Si component is increased, but in the conventional (Ti, Al, Si) N layer, When the Si content is about 10 atomic%, the high heat resistance required for high-speed gear cutting of alloy steel cannot be ensured, and in order to satisfy these requirements satisfactorily, the above 1-10 atomic% In order to use the (Ti, Al, Si) N layer containing 25 to 35 atomic% of Si component, which is much more than 25% by atom, while containing 25 to 35 atomic% of Si component as a hard coating layer, It is necessary to contain a predetermined amount of Ti to ensure a predetermined high temperature strength. In this case, however, the content ratio of the Al component is unavoidably low, and as a result, the high temperature hardness is extremely low. thing.

(B) the composition _{formula: [Ti 1- (A + B} ) Al A Si B] N ( provided that an atomic ratio, A is 0.01 to 0.06, B denotes the 0.25-0.35) satisfies A (Ti, Al, Si) N layer having a Si content of 25 to 35 atomic%;
_{Formula: [Ti 1- (C + D} ) Al C Si D] N ( provided that an atomic ratio, C is 0.30 to 0.45, D represents a 0.10 to 0.15) satisfies, relative (Ti, Al, Si) N layer with a large content ratio of Al component,
Are alternately laminated in a state in which each layer thickness is 5 to 20 nm (nanometer), this (Ti, Al, Si) N layer is formed by the above-described high Si by the thin laminated structure. (Ti, Al, Si) N layer (hereinafter referred to as thin layer A) containing excellent heat resistance, Si content rate is lower than the thin layer A, and relatively high Al content ( A relatively high high temperature hardness of the Ti, Al, Si) N layer (hereinafter referred to as the thin layer B).

(C) The (Ti, Al, Si) N layer having the alternately laminated structure of the thin layer A and the thin layer B of (b) above has excellent heat resistance required for high-speed gear cutting of alloy steel and a predetermined value. Although it has a high temperature hardness, it does not have a sufficiently satisfactory high temperature hardness, so it is provided as the upper layer of the hard coating layer, while the lower layer has insufficient heat resistance, but relatively Al (Ti, Al, Si) N layer having a composition corresponding to the above-mentioned conventional hard coating layer having a high component content and excellent high-temperature hardness,
Compositional formula: [Ti _{1− (E + F)} Al _E Si _F ] N (wherein E is 0.50 to 0.60 and F is 0.01 to 0.09 in terms of atomic ratio) (Ti, Al, Si) N layer of single phase structure,
The resulting hard coating layer has excellent heat resistance, high-temperature strength, and high-temperature hardness. Therefore, the coated high-speed tooth formed by vapor-depositing the hard coating layer is provided. Cutting tools should exhibit excellent wear resistance over a long period of time without chipping even in high-speed gear cutting of alloy steel with high heat generation.
The research results shown in (a) to (c) above were obtained.

This invention was made based on the above research results, and on the surface of a high-speed tool steel substrate,
(A) Both are composed of an upper layer and a lower layer made of (Ti, Al, Si) N, the upper layer has a thickness of 0.5 to 1.5 μm, and the lower layer has a thickness of 2 to 6 μm. ,
(B) Each of the upper layers has an alternate laminated structure of thin layers A and B having a layer thickness of 5 to 20 nm (nanometer),
The thin layer A is
Composition formula: [Ti _{1 − (A + B)} Al _A Si _B ] N (wherein A is 0.01 to 0.06 and B is 0.25 to 0.35 in atomic ratio) (Ti , Al, Si) N layer,
The thin layer B is
Composition formula: [Ti _{1− (C + D)} Al _C Si _D ] N (wherein C is 0.30 to 0.45 and D is 0.10 to 0.15 in terms of atomic ratio) (Ti , Al, Si) N layer,
(C) the lower layer has a single phase structure;
Composition formula: [Ti _{1− (E + F)} Al _E Si _F ] N (wherein E is 0.50 to 0.60 and F is 0.01 to 0.09 in atomic ratio) (Ti , Al, Si) N layer,
For coated high-speed gear cutting tools (surface-coated high-speed tool steel gear cutting tools) that exhibit excellent wear resistance in high-speed gear cutting of alloy steel, which is formed by vapor-depositing a hard coating layer consisting of It has characteristics.

Next, the reason why the numerical values of the hard coating layer of the coated high-speed gear cutting tool of the present invention are limited as described above will be described.
(A) Composition formula and layer thickness of the lower layer As described above, the Al component in the (Ti, Al, Si) N layer constituting the hard coating layer improves high-temperature hardness, while the Ti component has high-temperature strength. In addition, the Si component has an effect of improving heat resistance, and the lower layer has a relatively high Al component content to provide a high temperature hardness, but the E value indicating the Al content is If the proportion of the total amount of Ti and Si (atomic ratio, the same shall apply hereinafter) is less than 0.50, the proportion of Ti is relatively high, and excellent high-temperature hardness required for high-speed gear cutting of alloy steel. However, when the E value indicating the proportion of Al exceeds 0.60, the proportion of Ti becomes relatively small, resulting in a high temperature. The strength drops sharply, resulting in chipping (slight chipping). Since it becomes easy to produce, E value was set to 0.50-0.60.
Further, the F value indicating the proportion of Si is the proportion of the total amount of Ti and Al. If the F value is less than 0.01, the predetermined heat resistance cannot be ensured, while the F value exceeds 0.09. Since it is difficult to ensure the predetermined high-temperature strength, the F value was set to 0.01 to 0.09.
Further, if the layer thickness is less than 2 μm, the excellent high-temperature hardness cannot be imparted to the hard coating layer over a long period of time, resulting in a short tool life. On the other hand, if the layer thickness exceeds 6 μm, chipping occurs. The layer thickness was determined to be 2 to 6 μm because it easily occurs.

(B) Composition formula of upper layer thin layer A The Si component in (Ti, Al, Si) N of the upper layer thin layer A is relatively increased in content as described above to improve heat resistance. Therefore, it is contained for the purpose of adapting to high-speed gear cutting of alloy steel with high heat generation. Therefore, if the B value is less than 0.25, the desired excellent heat resistance cannot be ensured, while the B value is When 0.3 exceeds 0.35, even if a thin layer B having excellent high-temperature strength is present adjacently, a decrease in high-temperature strength of the upper layer is unavoidable and causes chipping. It was set as 25-0.35.
Further, the A value indicating the proportion of Al is the proportion of the total amount of Ti and Si, and if it is less than 0.01, the minimum high-temperature hardness cannot be ensured, causing wear promotion, while the same A When the value exceeds 0.06, a decreasing tendency appears in the high-temperature strength and causes chipping. Therefore, the A value was set to 0.01 to 0.06.

(C) Composition formula of upper layer thin layer B In the upper layer thin layer B, the Si component content ratio is relatively low, while the Al component content ratio is maintained relatively high. High temperature hardness is reinforced to reinforce the shortage of the high temperature hardness of the adjacent thin layer A, so that the excellent heat resistance of the thin layer A and the predetermined high temperature hardness of the thin layer B can be achieved. When the C value indicating the Al content ratio in the composition formula of the thin layer B is less than 0.30, the Al content ratio becomes too small, and a predetermined high-temperature hardness is formed. However, if the C value exceeds 0.45, the content ratio of the Ti component is relatively reduced, and the high temperature strength is reduced. Since it is unavoidable and causes chipping, the C value is set to 0.30 to 0.4. It was set as 5.
Further, if the D value indicating the proportion of Si is a proportion of the total amount of Ti and Al, and if it is less than 0.10, the heat resistance of the entire upper layer is unavoidably reduced, while if the D value exceeds 0.15, Since the high temperature strength of the entire upper layer is lowered, the D value is set to 0.10 to 0.15.

(D) Layer thicknesses of upper layer thin layer A and layer B If each layer thickness is less than 5 nm, it is difficult to form each thin layer clearly with the above composition. Excellent heat resistance and predetermined high-temperature hardness cannot be ensured, and when the thickness of each layer exceeds 20 nm, the disadvantages of each thin layer, that is, if it is thin layer A, high-temperature hardness is insufficient, thin In the case of the layer B, insufficient heat resistance appears locally in the layer, and this makes it easy for chipping to occur or promotes the progress of wear. Therefore, the thickness of each layer is set to 5 to 20 nm. It was.

(E) Layer thickness of the upper layer If the layer thickness is less than 0.5 μm, the excellent heat resistance of itself cannot be imparted to the hard coating layer over a long period of time, causing short tool life, while the layer thickness is If the thickness exceeds 1.5 μm, chipping is likely to occur. Therefore, the layer thickness is set to 0.5 to 1.5 μm.

  In the coated high-speed gear cutting tool of the present invention, the hard coating layer is composed of a (Ti, Al, Si) N layer, and the upper layer of the hard coating layer is excellent by adopting an alternate laminated structure of the thin layer A and the thin layer B. Since the lower layer of the single phase structure has excellent high-temperature hardness, even in high-speed gear cutting of alloy steel with high heat generation, there is no occurrence of chipping in the hard coating layer, It exhibits excellent wear resistance over a long period of time.

  Next, the coated high-speed gear cutting tool of the present invention will be specifically described with reference to examples.

The material is made of a high-speed tool steel of JIS / SKH51 and SKH55, and has an overall diameter of 75 mm × length: 110 mm by machining from a material having a diameter of 80 mm × length: 130 mm, And the high-speed gear cutting tool main body (solid hob) shown by the schematic perspective view in FIG.

(A) Next, a high speed gear cutting tool body (solid hob) made of the above two materials is used as a base, and each of these bases is ultrasonically cleaned in acetone and dried, and the arc shown in FIG. Attached along the outer peripheral portion at a predetermined distance in the radial direction from the central axis on the rotary table in the ion plating apparatus, each having a target composition shown in Table 1 as a cathode electrode (evaporation source) on one side. As the Ti-Al-Si alloy for forming the upper layer A having the corresponding component composition and the cathode electrode (evaporation source) on the other side, each had the same component composition corresponding to the target composition shown in Table 1. A Ti-Al-Si alloy for forming a thin layer B as an upper layer is disposed opposite to the rotary table, and the cathode is formed along the rotary table at a position shifted by 90 degrees from both the Ti-Al-Si alloys. The Ti-Al-Si alloy for the lower layer formed by mounting a cathode electrode (vapor source),
(B) First, after the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, the inside of the apparatus is heated to 400 ° C. with a heater, and then rotates on the rotary table while rotating on the rotary tool main body base. A DC bias voltage of −1000 V is applied, and a current of 100 A is passed between the Ti—Al—Si alloy for forming the lower layer and the anode electrode to generate an arc discharge. Bombarded with Ti-Al-Si alloy,
(C) Introducing nitrogen gas as a reaction gas into the apparatus to make a reaction atmosphere of 3 Pa, applying a DC bias voltage of −100 V to the gear cutting tool main body rotating while rotating on the rotary table, and An arc discharge is generated by flowing a current of 100 A between the Ti—Al—Si alloy for forming the lower layer and the anode electrode, so that the target composition shown in Table 1 is formed on the surface of the high speed gear cutting tool main body. (Ti, Al, Si) N layer having a single phase structure with a target layer thickness is deposited as a lower layer of the hard coating layer,
(D) Next, nitrogen gas was introduced into the apparatus as a reaction gas to make a reaction atmosphere of 2 Pa, and a DC bias voltage of −100 V was applied to the gear cutting tool main body rotating while rotating on the rotary table. In this state, a predetermined current in the range of 50 to 200 A is passed between the cathode electrode and the anode electrode of the Ti-Al-Si alloy for forming the thin layer A to generate arc discharge, and the gear cutting tool body A thin layer A having a predetermined layer thickness is formed on the surface of the substrate. After the thin layer A is formed, arc discharge is stopped, and instead, between the cathode electrode and the anode electrode of the Ti-Al-Si alloy for forming the thin layer B Similarly, a predetermined current in the range of 50 to 200 A is supplied to generate arc discharge to form a thin layer B having a predetermined thickness, and then the arc discharge is stopped (in this case, starting from the formation of the thin layer B). You may) Formation of the thin layer A by arc discharge between the cathode electrode and the anode electrode of the Ti-Al-Si alloy for forming the layer A, and arc discharge between the cathode electrode and the anode electrode of the Ti-Al-Si alloy for forming the thin layer B The thin layer B is repeatedly formed alternately, so that the thin layer A and the thin layer B having the target composition and the target layer thickness shown in Table 1 along the layer thickness direction are formed on the surface of the high-speed cutting tool main body. The coated high-speed gear cutting tools 1 to 6 of the present invention were manufactured by vapor-depositing the upper layers composed of the alternating layers with the overall target layer thicknesses shown in Table 1, respectively.

For comparison purposes, the high-speed gear cutting tool main body made of the above two types of materials is ultrasonically cleaned in acetone and dried, and then loaded into the arc ion plating apparatus shown in FIG. As the cathode electrode (evaporation source), a Ti—Al—Si alloy having a component composition corresponding to the target composition shown in Table 2 is attached, and the apparatus is first evacuated to a vacuum of 0.1 Pa or less. While being held, the inside of the apparatus was heated to 400 ° C. with a heater, and then a DC bias voltage of −1000 V was applied to the base of the gear cutting tool main body, and between the Ti—Al—Si alloy of the cathode electrode and the anode electrode A current of 100 A is applied to the electrode to generate an arc discharge, so that the surface of the main body of the gear cutting tool is bombarded with the Ti—Al—Si alloy, and then nitrogen gas is introduced into the apparatus as a reaction gas. The reaction atmosphere is 3 Pa, and the bias voltage applied to the base of the gear cutting tool body is lowered to −100 V to generate an arc discharge between the cathode electrode and the anode electrode of the Ti—Al—Si alloy. Thus, a hard coating layer composed of a (Ti, Al, Si) N layer having a single-phase structure having the target composition and target layer thickness shown in Table 2 is formed on the surface of the high-speed gear cutting tool main body by vapor deposition. Thus, coated high-speed gear cutting tools 1 to 6 (hereinafter referred to as comparative coated high-speed gear cutting tools 1 to 6) were produced, respectively.

Next, using the above-described coated high-speed gear cutting tools 1 to 6 and the comparative coated high-speed gear cutting tools 1 to 6, the material is alloy steel of JIS / SCr420H,

Module: 1.5, pressure angle: 14.5 degrees, number of teeth: 70, twist angle: 30 degrees right-hand twist, tooth width: processing of gears with dimensions and shapes of 22.5 mm,

Cutting speed (rotational speed): 240 m / min,
Feed: 3 mm / rev,
Processing form: climb, no shift, dry (air blow),
Under the conditions of high speed gear cutting (the cutting speed in the case of machining of the above JIS / SCr420H alloy steel gear is usually 150 m / min),
The number of gears processed until the flank wear width reached 0.2 mm was measured.
The measurement results are shown in Tables 1 and 2, respectively.

Further, as a high-speed gear cutting tool body, from a material having the same outer diameter: 105 mm × thickness: 22 mm made of a high-speed tool steel of the same material as JIS / SKH51 and SKH55, the pitch circle diameter by machining is: A disk-type pinion cutter (100 type described in JIS B 4356) shown in a schematic perspective view in FIG. 4 having an overall size of 100 mm × thickness: 18 mm and a shape of the number of cutter teeth: 50 was manufactured. .

  Next, the above-described high-speed gear cutting tool body (pinion cutter) is used as a base, and the surfaces of these bases are ultrasonically cleaned in acetone and dried, and then loaded into the arc ion plating apparatus shown in FIG. Then, under the same conditions as in Example 1, the lower layer composed of a (Ti, Al, Si) N layer having a single-phase structure with the target composition and target layer thickness shown in Table 1, and also in the layer thickness direction Along with the target composition shown in Table 1 and the upper layer consisting of alternating layers of thin layers A and B having a single target layer thickness, the present invention is coated by vapor deposition with the overall target layer thickness also shown in Table 1. High-speed gear cutting tools 7 to 12 were produced, respectively.

For comparison purposes, the surface of the base of the above-mentioned high-speed gear cutting tool body (pinion cutter) is ultrasonically cleaned in acetone and dried, and then loaded into the arc ion plating apparatus shown in FIG. By depositing a hard coating layer composed of a (Ti, Al, Si) N layer having a single phase structure with the target composition and target layer thickness shown in Table 2 under the same conditions as in Example 1 above. Coated gear cutting tools 7 to 12 (hereinafter referred to as comparative coated high speed gear cutting tools 7 to 12) were produced.

Next, using the above-described coated high-speed gear cutting tool 7 to 12 and comparative coated high-speed gear cutting tool 7 to 12, the material is made of alloy steel of JIS / SCr420H,

Module: 2, Pressure angle: 20 degrees, Number of teeth: 15, Teeth width: Processing of gears with dimensions and shapes of 22.5 mm,

Number of strokes: 1200 stroke / min,
Circumferential feed: 0.3 mm / stroke,
Radial feed: 0.03 mm / stroke,
Measures the number of gear machining until the flank wear width reaches 0.2 mm with high speed gear cutting (typically 750 strokes / min when machining JIS / SCr420H alloy steel gears) did. The measurement results are shown in Tables 1 and 2, respectively.

The thin layer A and thin layer B constituting the hard coating layer made of (Ti, Al, Si) N of the coated high-speed gear cutting tools 1 to 12 of the present invention obtained as a result, and the composition of the lower layer, In addition, the composition of the hard coating layer made of (Ti, Al, Si) N of the comparative coated high-speed gear cutting tools 1 to 12 was measured by energy dispersive X-ray analysis using a transmission electron microscope. The composition was substantially the same as the composition.

Further, when the average layer thickness of the constituent layers of the hard coating layer was subjected to cross-sectional measurement using a transmission electron microscope, all showed the same average value (average value of five locations) as the target layer thickness.

From the results shown in Tables 1 and 2, the coated high-speed gear cutting tool according to the present invention has a single-phase structure lower layer composed of (Ti, Al, Si) N and a hard coating layer each having a different composition, Consists of an upper layer having an alternating laminate structure of thin layers A and B each having a thickness of 5 to 20 nm, the lower layer has excellent high temperature hardness, and the upper layer has excellent heat resistance and is hard Since the coating layer combines these excellent characteristics, even when gear cutting of alloy steel gears is performed under high-speed gear cutting conditions with high heat generation, it has excellent chipping resistance and excellent resistance. Compared with the high-speed gear cutting conditions, comparatively coated high-speed gear cutting tools with a hard coating layer consisting of a (Ti, Al, Si) N layer with a single-phase structure are particularly resistant to heat. Wear progresses quickly due to the service life in a relatively short time It is clear that to reach.
As described above, the surface-coated high-speed tool steel gear cutting tool of the present invention (the present invention coated high-speed gear cutting tool) is not limited to gear cutting under normal conditions, particularly various alloy steel gears, etc. Even when the gear cutting is performed under high-speed gear cutting conditions with high heat generation, the hard coating layer exhibits excellent wear resistance and exhibits excellent performance over a long period of time. It is possible to satisfactorily cope with the high performance of the cutting device, the labor saving and energy saving of gear cutting, and the cost reduction.

The arc ion plating apparatus used for forming the hard coating layer which comprises the covering high-speed gear cutting tool of this invention is shown, (a) is a schematic plan view, (b) is a schematic front view. It is a schematic explanatory drawing of a normal arc ion plating apparatus. It is a schematic perspective view of a solid hob. It is a schematic perspective view of a disk-type pinion cutter.

Claims (1)

On the surface of the gear cutting tool body made of high-speed tool steel,
(A) Both are composed of an upper layer and a lower layer made of a composite nitride of Ti, Al, and Si, the upper layer has an average layer thickness of 0.5 to 1.5 μm, and the lower layer has an average layer thickness of 2 to 6 μm. Have
(B) Each of the upper layers has an alternately laminated structure of thin layers A and B each having an average layer thickness of 5 to 20 nm (nanometer),
The thin layer A is
Ti satisfying the composition formula: [Ti _{1− (A + B)} Al _A Si _B ] N (wherein A is 0.01 to 0.06 and B is 0.25 to 0.35 in atomic ratio) A composite nitride layer of Al and Si;
The thin layer B is
Ti satisfying the composition formula: [Ti _{1- (C + D)} Al _C Si _D ] N (wherein C is 0.30 to 0.45 and D is 0.10 to 0.15 in atomic ratio) A composite nitride layer of Al and Si,
(C) the lower layer has a single phase structure;
Ti satisfying the composition formula: [Ti _{1− (E + F)} Al _E Si _F ] N (wherein E represents 0.50 to 0.60 and F represents 0.01 to 0.09 in atomic ratio) A composite nitride layer of Al and Si;
A surface-coated high-speed tool steel cutting tool that exhibits excellent wear resistance in high-speed gear cutting of alloy steel, characterized in that the hard coating layer is formed by vapor deposition.

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