JP5099495B2 - Surface coated cutting tool - Google Patents

Description

  The present invention provides excellent chipping resistance and wear resistance even when cutting work materials with high weldability such as mild steel and stainless steel under high-speed cutting conditions with high heat generation. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits the properties.

  In general, for coated tools, throwaway inserts that are detachably attached to the tip of the cutting tool for turning and planing of various steel and cast iron materials, drilling of the work material, etc. Drills and miniature drills, and solid type end mills used for chamfering, grooving and shouldering of the work material, etc. A slow-away end mill tool that performs cutting work in the same manner as an end mill is known.

In addition, as a coated tool, on the surface of a tool base composed of tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet,
Composition _{formula: (Al 1-P-Q} Cr P M Q) N ( where, M is chosen Periodic Table 4a except Cr, 5a, elements of Group 6a, Si, B, from among Y 1 Seeds or two or more added components, and P and Q indicate the content ratio of Cr component and M component by atomic ratio)
There is known a coating tool formed by physical vapor deposition of a hard coating layer composed of a composite nitride layer of Al, Cr, and M satisfying the following (hereinafter collectively referred to as (Al, Cr, M) N). In addition, the (Al, Cr, M) N layer, which is a hard coating layer of the above-mentioned coated tool, has high temperature hardness due to the constituent component Al, high temperature strength due to the Cr, and heat resistance due to the coexistence of Cr and Al. In addition, the M component composed of one or more elements selected from the elements of groups 4a, 5a, and 6a of the periodic table excluding Cr, Si, B, and Y is the wear resistance of the hard coating layer. It is also known to exhibit excellent cutting performance when used for continuous cutting and interrupted cutting of various general steels and ordinary cast iron, etc. .

Further, the above-mentioned coated tool, for example, the above-mentioned tool base is loaded into an arc ion plating apparatus which is a kind of physical vapor deposition apparatus shown schematically in FIG. Between the cathode electrode (evaporation source) in which an Al—Cr—M alloy having a predetermined composition corresponding to the target composition of the hard coating layer is set and the anode electrode, for example, at a current of 90 A. Arc discharge is generated under the conditions, and nitrogen gas is introduced as a reaction gas into the apparatus at the same time to form a reaction atmosphere of, for example, 2 Pa. On the other hand, the tool base is applied with a bias voltage of, for example, −100 V. It is also known that a hard coating layer made of an (Al, Cr, M) N layer having a target composition is deposited on the surface of a substrate.
JP 9-41127 A JP 2004-106183 A JP 2004-269985 A JP 2006-82209 A

  In recent years, the use of FA for cutting devices has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting processing. With this, cutting processing is further accelerated and versatility of cutting tools is required. However, in the above-mentioned conventional coated tool, there is no problem when it is used for cutting under normal cutting conditions such as low alloy steel, carbon steel, cast iron, etc. When the work material with high weldability, such as stainless steel, is used for high-speed cutting with high heat generation, the heat resistance and high-temperature strength of the hard coating layer will be insufficient, resulting in chipping (small chipping). ), The occurrence of thermoplastic deformation, uneven wear, etc., and the progress of wear progresses, so that the service life is reached in a relatively short time.

  In view of the above, the inventors of the present invention have a hard coating even when cutting a work material having high weldability such as mild steel and stainless steel under high-speed cutting conditions with high heat generation. In order to develop a coated tool exhibiting excellent chipping resistance and wear resistance, the following findings were obtained as a result of research by focusing on the above-mentioned conventional coated tool.

(A) The (Al, Cr, M) N layer, which is a hard coating layer of the above-mentioned conventional coated tool, is formed as a layer having a substantially single uniform composition over the entire layer. Rather than having a uniform composition layer, it is constructed as a layer consisting of a lower layer and an upper layer, and the lower layer is constructed as an (Al, Cr, M) N layer having a substantially uniform composition as in the prior art. In addition, the upper layer has a composition gradient type concentration distribution structure in which the content ratio of N as a constituent component of the layer decreases from the lower layer side toward the upper layer surface (along the layer thickness direction). When formed as an (Al, Cr, M) N layer, the hard coating layer composed of a two-layer structure of a uniform composition lower layer and a composition gradient type upper layer maintains a predetermined high temperature hardness, high temperature strength, and heat resistance. In addition, by having excellent thermal conductivity, heat dissipation, and lubricity, it is even more To improve wear resistance.

(B) That is, in the lower layer composed of the (Al, Cr, M) N layer having a substantially uniform composition, the constituent Al component improves the high temperature hardness and heat resistance of the hard coating layer, and the Cr component is high temperature. It has the effect of improving the strength and improving high-temperature oxidation resistance by coexistence of Cr and Al. Further, among the M components, elements of the periodic tables 4a, 5a and 6a excluding Cr, Si, B, Has the effect of improving the wear resistance of the hard coating layer, and Y has the effect of improving the high temperature oxidation resistance of the hard coating layer, but the surface roughness of the layer formed by vapor deposition is large. When this is used as a hard coating layer for cutting tools, the lubricity with work materials with particularly high weldability becomes insufficient, and as a result, wear resistance is satisfactory in high-speed cutting of these work materials. On the surface of the lower layer When a composition gradient type (Al, Cr, M) N layer having a concentration distribution structure in which the N content ratio decreases toward the upper layer surface is formed by vapor deposition, the surface of the upper layer having a low N content ratio is roughened. Since the degree of smoothness is small and the lubricity is excellent, the upper layer having a surface layer with a low N content ratio has high thermal conductivity and excellent heat dissipation, so that mild steel, stainless steel, etc. In high-speed cutting of work materials with high weldability, even if the hard coating layer is heated to a high temperature, heat is immediately dissipated, it is not overheated, thermoplastic deformation or uneven wear does not occur, and long-term Exhibit excellent wear resistance.

(C) A hard coating layer composed of a lower layer composed of a substantially uniform (Al, Cr, M) N layer and an upper layer composed of a composition gradient type (Al, Cr, M) N layer is shown in FIG. Using a conventionally known arc ion plating apparatus shown in Fig. 1 in a schematic plan view, an arc discharge is generated between a cathode electrode (evaporation source) and an anode electrode of an Al-Cr-M alloy having a predetermined composition. Then, a substantially uniform (Al, Cr, M) N layer having a predetermined composition is deposited on the surface of the tool base with an average layer thickness of 2 to 10 μm, and then an Al—Cr—M alloy cathode electrode (evaporation source). By gradually reducing the nitrogen content ratio of the atmosphere in the apparatus while continuing the arc discharge between the anode electrode and the anode electrode, the nitrogen content ratio of the upper layer surface has an average layer thickness of 0.3-1 μm Compositional gradient type (Al, Cr, M ) The N layer can be formed by vapor deposition.

This invention was made based on the above research results,
"On the surface of the tool base made of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) The lower layer has an average layer thickness of 2 to 10 μm, and its composition is
Composition _{formula: (Al 1-α-β} Cr α M β) N γ
In the atomic ratio, 0.2 ≦ α ≦ 0.4, 0.01 ≦ β ≦ 0.25, 0.9 ≦ γ ≦ 1 (where M is the periodic table 4a excluding Cr) , 5a, 6a group element, Si, B, or Y selected from one or more additive components, α is the Cr content, β is the M content, and γ is the N content A composite nitride layer of Al and Cr having a uniform composition satisfying
(B) As an upper layer, it has an average layer thickness of 0.3-1 μm, and its composition is
Composition formula: (Al _1-α-β Cr _α M _β ) N _δ
In the atomic ratio, 0.2 ≦ α ≦ 0.4, 0.01 ≦ β ≦ 0.25, 0.5 ≦ δ <1 (where M is the periodic table 4a excluding Cr) , 5a, 6a group element, Si, B, or Y selected from one or more additive components, α is the Cr content, β is the M content, and γ is the N content And a concentration distribution structure in which the nitrogen content in the upper layer decreases from the lower layer side toward the upper layer surface, and the upper layer surface. A composition-graded Al, Cr, and M composite nitride layer in which the nitrogen content ratio (ε value) satisfies 0 ≦ ε ≦ 0.35,
A surface-coated cutting tool formed by vapor-depositing a hard coating layer composed of the above (a) and (b). "
It has the characteristics.

  Next, the reason why the numerical values of the lower layer and the upper layer of the coated tool of the present invention are limited as described above will be described.

(A) Lower layer The lower layer is composed of an Al, Cr, and M composite nitride layer ((Al, Cr, M) N layer) having a substantially uniform composition. The high temperature hardness and heat resistance in the hard coating layer are improved, the Cr component has the effect of improving the high temperature strength, the high temperature oxidation resistance by coexistence of Cr and Al, and of the M component, The elements 4a, 5a and 6a of the periodic table excluding Cr, Si and B, have the effect of improving the wear resistance of the hard coating layer, and Y improves the high temperature oxidation resistance of the hard coating layer. There is an action to make. However, if the α value (atomic ratio), which indicates the content ratio of Cr in the total amount of Al and M, is less than 0.2, it is minimally required for high-speed cutting of work materials with high weldability. However, when the α value (atomic ratio) exceeds 0.4, the relative Al content decreases, resulting in a decrease in high-temperature hardness and heat resistance. The improvement in wear resistance can no longer be expected due to the occurrence of uneven wear, the occurrence of thermoplastic deformation, etc., and the β value (atomic ratio) indicating the content ratio of the M component in the total amount of Al and Cr ) Is less than 0.01, improvement in properties such as wear resistance and high-temperature oxidation resistance due to inclusion of the M component cannot be expected. On the other hand, if the β value exceeds 0.25, the strength is reduced to high-temperature strength. Since a tendency appears, α value is 0.2 to 0.4, β value is 0. It was defined as 01 to 0.25.
Note that the β value is a total value of the content ratios of the respective components including Si, B, and Y elements included in the periodic table 4a, 5a, and 6a excluding Cr, which are contained as the M component.
Further, when the total amount of the metal components Al, Cr, and M in the lower layer is 1, the γ value indicating the content ratio (however, atomic ratio) of the N component to these metal components is in the range of 0.9 ≦ γ ≦ 1. Since the high temperature hardness and high temperature strength required for high-speed cutting of a work material with high weldability cannot be maintained, the N component content (γ value) (however, the atomic ratio) is It was determined that 0.9 ≦ Y ≦ 1.
Further, if the average layer thickness of the lower layer is less than 2 μm, it is insufficient to exhibit its excellent wear resistance over a long period of time, while if the average layer thickness exceeds 10 μm, high-speed cutting is required. Since the chipping is likely to occur at the cutting edge, the average layer thickness is determined to be 2 to 10 μm.

(B) Upper layer The composition-gradient Al, Cr, and M composite nitride layer ((Al, Cr, M) N layer) constituting the upper layer has a N content ratio from the lower layer side toward the upper layer surface. Has a concentration distribution structure that decreases. Therefore, the upper layer in the vicinity of the lower layer has a composition close to the average composition of the lower layer, and the lower layer and the upper layer are formed as layers having compositional continuity. Even if a hard coating layer is formed from a two-layer structure, an upper layer having high bonding strength between layers and excellent high-temperature hardness, high-temperature strength, and heat resistance is formed. On the other hand, since the N content in the (Al, Cr, M) N layer decreases toward the surface side of the upper layer, the surface of the upper layer is excellent in thermal conductivity and heat dissipation and has a smooth surface. A layer having excellent properties is formed, and lubricity with the work material is improved.
Regarding the average composition of the upper layer, the Cr content ratio (α value) and the M content ratio (β value) in the total amount of Al, Cr, and M are the same as in the lower layer. α ≦ 0.4 and 0.01 ≦ β ≦ 0.25.
Moreover, when the total amount of the metal components Al, Cr, and M in the upper layer is 1, with respect to the content ratio of N relative to these metal components, the upper layer as a whole ensures a predetermined high temperature hardness, high temperature strength, and heat resistance. Therefore, the content ratio (δ value) of N as an average composition was determined to be 0.5 ≦ δ <1.
However, when the content ratio (ε value) of the N component in the layer on the surface of the upper layer exceeds 0.35, the effect of improving the thermal conductivity, heat dissipation, and surface smoothness on the surface of the upper layer is small, and as a result Since the lubricity and wear resistance with the work material are not sufficient, when the total amount of Al, Cr, M on the surface of the upper layer is 1, the N content on the upper layer surface with respect to these metal components The ratio (ε value) was set to 0 to 0.35. Here, the value of ε is 0 (zero), but the upper layer surface is not a composite nitride of Al, Cr, and M, but is formed of an alloy of Al, Cr, and M. In the present invention, not only the surface of the upper layer is a composite nitride of Al, Cr and M but also a case of an Al—Cr—M alloy, for the sake of convenience, a composite nitride layer of Al, Cr and M ( (Al, Cr, M) N layer) (in the case where the upper layer surface is an Al—Cr—M alloy, naturally, ε = 0).
Also, if the average layer thickness of the composition-graded upper layer is less than 0.3 μm, it is not possible to sufficiently exhibit excellent thermal conductivity and heat dissipation characteristics, and the average layer thickness is 1 μm. If it exceeds the upper limit, welding tends to occur between the workpiece and the average thickness of the upper layer is determined to be 0.3 to 1 μm.
Therefore, a hard coating layer having a two-layer structure formed of a lower layer made of a uniform composition (Al, Cr, M) N layer and an upper layer made of a composition gradient type (Al, Cr, M) N layer is In addition to excellent high-temperature hardness, high-temperature strength, and heat resistance, it also has excellent thermal conductivity, heat dissipation, and surface smoothness, and excellent chipping resistance in high-speed cutting of work materials with high weldability. Demonstrate and wear resistance.

  In the coated tool of the present invention, the substantially uniform (Al, Cr, M) N layer constituting the lower layer of the hard coated layer has excellent high-temperature hardness, heat resistance, and high-temperature strength. In addition to the above characteristics, the upper layer composed of a composition gradient type (Al, Cr, M) N layer having a concentration distribution structure in which the N content ratio decreases from the surface toward the upper layer surface has excellent thermal conductivity, Because of its heat dissipation and surface smoothness, the hard coating layer as a whole has excellent high temperature hardness, heat resistance, high temperature strength, heat dissipation and lubricity. Even when such a highly weldable work material is machined under high-speed conditions with high heat generation, chipping, uneven wear, and thermoplastic deformation do not occur in the hard coating layer, providing excellent chipping resistance over a long period of time. And exhibits wear resistance.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders are blended in the composition shown in Table 1, wet mixed by a ball mill for 72 hours, dried, and then pressed into a green compact at a pressure of 100 MPa. Medium, sintered at 1400 ° C for 1 hour, after sintering, WC-based carbide with honing of R: 0.03 on the cutting edge and chip shape of ISO standard CNMG120408 Alloy tool bases A-1 to A-10 were formed.

In addition, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, mix these raw material powders into the composition shown in Table 2, wet mix for 24 hours with a ball mill, dry, and press-mold into green compact at 100 MPa pressure The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to meet ISO standards / Tool bases B-1 to B-6 made of TiCN base cermet having a chip shape of CNMG120408 were formed.

(A) Next, each of the tool bases A-1 to A-10 and B-1 to B-6 is ultrasonically cleaned in acetone and dried, and then the arc ion plating shown in FIG. Attached along the outer periphery at a position away from the central axis on the turntable in the apparatus in the radial direction along the outer periphery, and an Al-Cr-M alloy having a predetermined composition is arranged as a cathode electrode (evaporation source), Furthermore, a cathode electrode made of metal Ti for bombard cleaning is arranged,
(B) First, the inside of the apparatus is heated to 500 ° C. with a heater while the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, and then the tool base that rotates while rotating on the rotary table is −1000 V. A DC bias voltage is applied and a current of 100 A is passed between the cathode electrode and anode electrode for bombard cleaning made of metal Ti to generate an arc discharge, thereby bombard cleaning the tool base surface.
(C) Next, nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 4 Pa, a DC bias voltage of −100 V is applied to the tool base that rotates while rotating on the rotary table, and An arc discharge is generated by passing a current of 120 A between the cathode electrode (evaporation source) made of the Al—Cr—M alloy and the anode electrode, and the surfaces of the tool base are shown in Tables 3 and 4. After vapor-depositing the (Al, Cr, M) N layer with the target (uniform) composition and target average layer thickness,
(D) While continuing arc discharge between the cathode electrode (evaporation source) made of the Al—Cr—M alloy and the anode electrode, the atmosphere in the apparatus is gradually switched from the nitrogen gas atmosphere to the argon gas atmosphere. Finally, in a 0.5 Pa nitrogen-argon mixed gas atmosphere or argon gas atmosphere, a current of 120 A is passed between the cathode electrode (evaporation source) and the anode electrode to generate arc discharge, By vapor-depositing the composition gradient type (Al, Cr, M) N layer having the target average composition, the target surface N amount, and the target average layer thickness shown in Table 3 and Table 4 as an upper layer,
The surface-coated throwaway tips (hereinafter referred to as the present invention-coated tips) 1 to 16 as the present invention-coated tools were produced, respectively.
The “surface N amount” in Examples 1 to 3 is the composition of the surface of the upper layer composed of a composition gradient type (Al, Cr, M) N layer (Al _1−α−β Cr _α M _β ). The ε value (where 0 ≦ ε ≦ 0.35) when represented by N _ε .

Comparative Example 1

For the purpose of comparison, the tool substrates A-1 to A-10 and B-1 to B-6 were ultrasonically cleaned in acetone and dried, and then installed in the arc ion plating apparatus shown in FIG. Then, an Al—Cr alloy having a predetermined composition is mounted as a cathode electrode (evaporation source). First, the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, and the inside of the apparatus is heated to 500 ° C. with a heater. Then, a DC bias voltage of −1000 V is applied to the tool base, and an arc discharge is generated by flowing a current of 100 A between the cathode electrode (evaporation source) and the anode electrode. Then, nitrogen gas is introduced as a reaction gas into the apparatus to make a reaction atmosphere of 3 Pa, and the bias voltage applied to the tool base is lowered to −100 V, and the Al—Cr— An arc discharge is generated between the cathode electrode (evaporation source) made of an alloy and the anode electrode, so that the surface of each of the tool bases A-1 to A-10 and B-1 to B-6 is shown in Table 5, By vapor-depositing the (Al, Cr, M) N layer with the target (uniform) composition and target average layer thickness shown in Table 6 as a hard coating layer,
Comparative surface-coated throwaway tips (hereinafter referred to as comparative coated tips) 1 to 16 as comparative coated tools were produced, respectively.

Next, in the state where each of the above various coated chips is screwed to the tip of the tool steel tool with a fixing jig, the present coated chips 1-16 and the comparative coated chips 1-16,
Work material: JIS / S55C round bar,
Cutting speed: 350 m / min. ,
Cutting depth: 1.2 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 10 minutes,
Dry high-speed continuous cutting test of carbon steel under the conditions (cutting condition A) (normal cutting speed is 200 m / min.),
Work material: JIS / SCM440 round bar,
Cutting speed: 370 m / min. ,
Cutting depth: 1.5 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 10 minutes,
Dry high-speed continuous cutting test of alloy steel under the following conditions (cutting condition B) (normal cutting speed is 250 m / min.),
Work material: JIS / SUS304 round bar,
Cutting speed: 250 m / min. ,
Cutting depth: 1.2 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 5 minutes,
Dry high-speed intermittent cutting test of stainless steel under the conditions (cutting condition C) (normal cutting speed is 180 m / min.),
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 7.

As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, ZrC of 1.2 μm Powder, 2.3 μm Cr ₃ C ₂ powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C [by mass ratio, TiC / WC = 50/50] powder, and 1 Prepare 8 μm Co powder, mix these raw material powders with the composition shown in Table 8, add wax, ball mill in acetone for 24 hours, dry under reduced pressure, and press at a pressure of 100 MPa. The green compacts were press-molded, and these green compacts were heated to a predetermined temperature in the range of 1370 to 1470 ° C. at a rate of temperature increase of 7 ° C./min in a 6 Pa vacuum atmosphere. After holding at temperature for 1 hour, sintering under furnace cooling conditions Thus, three types of tool base forming round bar sintered bodies having diameters of 8 mm, 13 mm, and 26 mm are formed, and further, the three kinds of round bar sintered bodies are shown in Table 10 by grinding. In combination, the diameter x length of the cutting edge is 6 mm x 13 mm, 10 mm x 22 mm, and 20 mm x 45 mm, respectively, and each is made of a WC-based cemented carbide with a 4-flute square shape with a twist angle of 30 degrees Tool bases (end mills) C-1 to C-8 were produced.

Subsequently, the surfaces of these tool bases (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and then charged into the arc ion plating apparatus shown in FIG. Under the same conditions as in Example 1, the target (uniform) composition shown in Table 9 and the (Al, Cr, M) N layer having the target average layer thickness as the lower layer, and the target average composition also shown in Table 9; By forming a composition gradient type (Al, Cr, M) N layer having a target surface N amount and a target average layer thickness as an upper layer,
The surface-coated carbide end mills (hereinafter referred to as the present invention-coated end mills) 1 to 8 as the present invention-coated tools were produced, respectively.

Comparative Example 2

For the purpose of comparison, the surface of the tool base (end mill) C-1 to C-8 was ultrasonically cleaned in acetone and dried, and one cathode electrode (evaporation source) shown in FIG. An arc ion plating apparatus is provided, and an (Al, Cr, M) N layer having a target (uniform) composition and a target average layer thickness shown in Table 10 is deposited under the same conditions as in Comparative Example 1 above. By
Comparative surface coated carbide end mills (hereinafter referred to as comparative coated end mills) 1 to 8 as comparative coated tools were produced, respectively.

Next, of the present invention coated end mills 1-8 and comparative coated end mills 1-8,
About this invention coated end mills 1-3 and comparative coated end mills 1-3,
Work material-Plane size: 100 mm x 250 mm, thickness: 50 mm JIS / S55C plate material,
Cutting speed: 150 m / min. ,
Groove depth (cut): 5 mm,
Table feed: 400 mm / min,
Carbon steel dry high-speed grooving test (normal cutting speed is 100 m / min.),
About this invention coated end mills 4-6 and comparative coated end mills 4-6,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SCM440 plate material,
Cutting speed: 180 m / min. ,
Groove depth (cut): 8 mm,
Table feed: 450 mm / min,
Dry high-speed grooving test of alloy steel under the conditions of (normal cutting speed is 120 m / min.),
About this invention coated end mills 7 and 8 and comparative coated end mills 7 and 8,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 160 m / min. ,
Groove depth (cut): 16 mm,
Table feed: 350 mm / min,
Stainless steel dry high-speed grooving test (normal cutting speed is 100 m / min.),
In each high-speed groove cutting test, the cutting groove length was measured until the flank wear width of the outer peripheral edge of the cutting edge reached 0.1 mm, which is a guide for the service life. The measurement results are shown in Tables 9 and 10, respectively.

  The diameters produced in Example 2 above were 8 mm (for forming the tool bases C-1 to C-3), 13 mm (for forming the tool bases C-4 to C-6), and 26 mm (tool bases C-7 and C). -8 for forming), and from these three types of round bar sintered bodies, the diameter x length of the groove forming part is 4 mm x 13 mm (tool base D) by grinding. −1 to D-3), 8 mm × 22 mm (tool base D-4 to D-6), and 16 mm × 45 mm (tool bases D-7 and D-8), and all having a twist angle of 30 degrees 2 WC-base cemented carbide tool bases (drills) D-1 to D-8 having a single-blade shape were produced, respectively.

Next, the cutting edges of these tool bases (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone, and dried to the arc ion plating apparatus shown in FIG. Then, under the same conditions as in Example 1 above, the target (uniform) composition and target average layer thickness (Al, Cr, M) N layer shown in Table 11 is deposited as a lower layer, By vapor-depositing the composition gradient type (Al, Cr, M) N layer having the target average composition, target surface N amount, and target average layer thickness shown in Table 11 as an upper layer,
The surface-coated carbide drills (hereinafter referred to as the present invention-coated drills) 1 to 8 as the present invention-coated tools were produced, respectively.

Comparative Example 3

For the purpose of comparison, the surfaces of the above-mentioned tool bases (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone and dried, and the arc ion plating shown in FIG. A hard coating layer composed of an (Al, Cr, M) N layer having a target (uniform) composition and a target average layer thickness shown in Table 12 is formed by vapor deposition under the same conditions as in Comparative Example 1 above. By doing
Comparative surface coated carbide drills (hereinafter referred to as comparative coated drills) 1 to 8 as comparative coated tools were produced, respectively.

Next, of the present invention coated drills 1-8 and comparative coated drills 1-8, for the present invention coated drills 1-3 and comparative coated drills 1-3,
Work material-Plane size: 100 mm x 250 mm, thickness: 50 mm JIS / S55C plate material,
Cutting speed: 140 m / min. ,
Feed: 0.20 mm / rev,
Hole depth: 8 mm,
Wet high-speed drilling test of carbon steel under the conditions (normal cutting speed is 80 m / min.),
About this invention coated drill 4-6 and comparative coated drill 4-6,

Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SCM440 plate material,
Cutting speed: 150 m / min. ,
Feed: 0.25 mm / rev,
Hole depth: 15 mm,
Wet high-speed drilling cutting test of alloy steel under the conditions (normal cutting speed is 80 m / min.),
About this invention covering drills 7 and 8 and comparative covering drills 7 and 8,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 140 m / min. ,
Feed: 0.15 mm / rev,
Hole depth: 28 mm,
Wet high-speed drilling test of stainless steel under the conditions of (normal cutting speed is 80 m / min.),
In each wet high-speed drilling test (using water-soluble cutting oil), the number of drilling processes until the flank wear width of the tip cutting edge surface reached 0.3 mm was measured. The measurement results are shown in Tables 11 and 12, respectively.

  The uniform composition (Al, Cr) constituting the lower layer of the hard coating layer of the present coated chips 1-16, the present coated end mills 1-8, and the present coated drills 1-8 as the present coated tool obtained as a result of this. , M) Composition of the N layer, and a uniform composition (Al, Cr, M) N layer of the comparative coated tips 1-16, comparative coated end mills 1-8 and comparative coated drills 1-8 as comparative coated tools, Further, the composition (ie, target average composition and target surface N amount) of the composition gradient type (Al, Cr, M) N layer constituting the upper layer of the coated tool of the present invention is a surface using Auger spectroscopy. As a result of analysis, it showed substantially the same composition as each target composition.

  Further, the uniform composition (Al, Cr, M) N layer of the present invention coated tool, the composition gradient type (Al, Cr, M) N layer, and the uniform composition (Al, Cr, M) N layer of the above comparative coated tool. When the average layer thickness was measured by a cross-section using a scanning electron microscope, all showed the same average value (average value of five locations) as the target layer thickness.

  From the results shown in Tables 7 and 9 to 12, the coated tool of the present invention is uniform even when a work material with high weldability such as mild steel or stainless steel is cut under high-speed cutting conditions with high heat generation. The lower layer composed of the (Al, Cr, M) N layer having the composition has excellent high temperature hardness, heat resistance and high temperature strength, and is composed of the composition gradient type (Al, Cr, M) N layer. However, it exhibits excellent thermal conductivity, heat dissipation, and lubricity, prevents the hard coating layer from being overheated, and suppresses the occurrence of uneven wear and thermoplastic deformation, thereby eliminating the occurrence of chipping. In comparison with the coated tool in which the hard coating layer is composed of only a uniform composition (Al, Cr, M) N layer, the thermal conductivity and heat dissipation are excellent. Due to insufficient lubricity, high heat generated during high-speed cutting Te, chipping, thermal plastic deformation results in uneven wear and the like, it is clear that lead to a relatively short time service life.

  As described above, the coated tool of the present invention is capable of high-speed heat generation with high heat generation of a work material having high weldability such as mild steel and stainless steel as well as cutting under normal conditions such as general steel and ordinary cast iron. Also in cutting, it shows excellent cutting performance over a long period of time, so it can fully satisfactorily respond to FA conversion of cutting equipment, labor saving and energy saving of cutting processing, and further cost reduction. .

It is a schematic plan view of the arc ion plating apparatus used for forming a hard coating layer.

Claims (1)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) The lower layer has an average layer thickness of 2 to 10 μm, and its composition is
Composition _{formula: (Al 1-α-β} Cr α M β) N γ
In the atomic ratio, 0.2 ≦ α ≦ 0.4, 0.01 ≦ β ≦ 0.25, 0.9 ≦ γ ≦ 1 (where M is the periodic table 4a excluding Cr) , 5a, 6a group element, Si, B, or Y selected from one or more additive components, α is the Cr content, β is the M content, and γ is the N content A composite nitride layer of Al and Cr having a uniform composition satisfying
(B) As an upper layer, it has an average layer thickness of 0.3-1 μm, and its composition is
Composition formula: (Al _1-α-β Cr _α M _β ) N _δ
In the atomic ratio, 0.2 ≦ α ≦ 0.4, 0.01 ≦ β ≦ 0.25, 0.5 ≦ δ <1 (where M is the periodic table 4a excluding Cr) , 5a, 6a group element, Si, B, or Y selected from one or more additive components, α is a Cr content, β is an M content, δ is an N content And a concentration distribution structure in which the nitrogen content in the upper layer decreases from the lower layer side toward the upper layer surface, and the upper layer surface. A composition-graded Al, Cr, and M composite nitride layer in which the nitrogen content ratio (ε value) satisfies 0 ≦ ε ≦ 0.35,
A surface-coated cutting tool formed by vapor-depositing a hard coating layer composed of the above (a) and (b).

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