JP2008188740A - Surface coated cutting tool with excellent chipping resistance due to hard coating layer in heavy cutting of difficult-to-cut materials - Google Patents

Abstract

Provided is a surface-coated cutting tool that exhibits excellent chipping resistance in a hard coating layer in heavy cutting of difficult-to-cut materials.
The surface of the tool base has (a) a lower layer made of a composite nitride layer of Cr and Y, and (b) an oxygen concentration distribution structure in which the oxygen content increases in the layer thickness direction. An upper layer composed of a composition-graded vanadium oxynitride layer substantially free of oxygen on the lower surface and substantially free of nitrogen on the outermost surface, and a hard coating layer composed of (a) and (b) above. A surface-coated cutting tool.
[Selection figure] None

Description

  This invention is particularly useful when cutting difficult-to-cut materials that have high viscosity such as Al alloy, mild steel, stainless steel, etc. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent chipping resistance and lubricity with a hard coating layer.

  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, shouldering, etc. 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.

Further, as a coated tool, at least a chromium nitride (hereinafter referred to as CrN) is formed on the surface of a tool base made of tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet. It is known that coated tools formed by physical vapor deposition of a hard coating layer as a hard coating layer and that the CrN layer has excellent lubricity and wear resistance.
Further, in the CrN layer as described above, 0.01 to 10 atomic% yttrium (hereinafter referred to as Y) is contained, and a composite nitride layer of Cr and Y (hereinafter referred to as (Cr, Y) N layer). It is also known to improve its hardness by forming (shown).

Furthermore, the CrN layer of the conventional coated tool or the (Cr, Y) N layer is loaded into an arc ion plating apparatus, for example, a kind of physical vapor deposition apparatus schematically shown in FIG. In the state where the inside of the apparatus is heated to a temperature of, for example, 500 ° C. with a heater, a condition of, for example, a current of 90 A is set between the cathode electrode (evaporation source) on which Cr alloy or Cr—Y alloy is set and the anode electrode. At the same time, an arc discharge is generated and nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of, for example, 2 Pa. On the other hand, vapor deposition is performed on the substrate under a condition in which a bias voltage of, for example, −100 V is applied, It is also known that the CrN layer or the (Cr, Y) N layer can be formed on the substrate surface.
JP 2006-21257 A JP 2002-337008 A Japanese Patent Laid-Open No. 2001-181824

  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, energy saving, and cost reduction for cutting processing. As a result, cutting tools are affected as much as possible by the material type of the work material. There is a tendency to demand a cutting tool that can cut as many grades as possible, but in the above-mentioned conventional coated tools, this is applied to general steel such as low alloy steel and carbon steel, and ductile There is no problem when it is used for normal cutting of ordinary cast iron such as cast iron and gray cast iron, but difficult to cut such as Al alloy, mild steel, stainless steel, etc., which has high chip viscosity and easily adheres to the tool surface. If cutting of the material (work material) is performed under heavy cutting conditions such as high cutting and high feed that locally apply a high load to the cutting edge, the work material and chips are generated by the heat generated during cutting. Is heated to high temperature As a result, the adhesiveness and reactivity to the surface of the hard coating layer further increase, and as a result, the occurrence of chipping (slight chipping) at the cutting edge increases rapidly. At present, the service life is reached in a relatively short time.

In view of the above, the present inventors, in particular, are hard when cutting difficult-to-cut materials such as Al alloy, mild steel, and stainless steel under heavy cutting conditions such as high cutting and high feed. As a result of conducting research while focusing on the above-mentioned conventional coated tools in order to develop a coated tool that exhibits excellent chipping resistance with a coating layer,
(A) The CrN layer, which is a hard coating layer of the conventional coated tool, contains a Y component such that the Y content in the total amount with Cr is 0.1 to 10 atomic% (Cr, Y). When the N layer is constituted, the hardness of the (Cr, Y) N layer becomes large due to the inclusion of the Y component, and the cutting tool coated with the (Cr, Y) N layer shows excellent wear resistance. On the other hand, since the lubricity of the (Cr, Y) N layer is not sufficient due to the inclusion of the Y component, in heavy cutting of difficult-to-cut materials such as Al alloy, mild steel, stainless steel, etc., due to insufficient lubricity , Chipping is likely to occur.

(B) Therefore, the (Cr, Y) N layer is formed as a lower layer of the hard coating layer with an average layer thickness of 1 to 5 μm, and an upper layer of vanadium oxide (vanadium oxide is the degree of oxidation) Can form various compound forms such as VO, V ₂ O ₃ and VO _2, but these are collectively referred to as VO), and the VO layer is excellent in lubricity. Even when the work material (hard-to-cut material) and its chips are heated at high temperatures due to the heat generated by the tool, the cutting edge (the rake face and flank face, the cutting edge ridge line where these two surfaces intersect), the work material and the chips In the meantime, excellent lubricity and welding resistance are always ensured, and the adhesion and reactivity of the work material and chips to the surface of the cutting edge are significantly reduced.

(C) However, when a VO layer is directly provided as an upper layer on a lower layer made of a (Cr, Y) N layer, the (Cr, Y) N layer as the lower layer and the VO layer as the upper layer are provided. Adhesion with the layer is not sufficient, and the high temperature strength of the VO layer itself, which is the upper layer, is not sufficient, which is due to insufficient adhesion between the lower layer and the upper layer of the hard coating layer and insufficient high temperature strength of the upper layer. The occurrence of chipping cannot be sufficiently prevented.

(D) In providing the VO layer on the lower layer composed of the (Cr, Y) N layer, the surface of the (Cr, Y) N layer is substantially free of oxygen-containing vanadium nitride (hereinafter referred to as “vanadium nitride”). VN) is formed by vapor deposition, and the vapor deposition is continued. As the thickness of the upper layer increases, the oxygen content ratio of the deposited layer is gradually increased (the nitrogen content ratio is gradually increased). When the deposition is performed so that vanadium oxide containing substantially no nitrogen is formed on the surface of the upper layer, the upper layer is a vanadium oxynitride layer as a whole, but the composition changes in the layer thickness direction. As a result, a composition-graded upper layer having an oxygen (nitrogen) concentration distribution is formed along the thickness direction of the upper layer, where the oxygen content gradually increases, while the nitrogen content decreases gradually. thing.

(E) And the upper layer made of the composition gradient type vanadium oxynitride is vanadium nitride which does not substantially contain oxygen in the vicinity of the lower layer made of the (Cr, Y) N layer, On the other hand, the surface area of the composition graded upper layer is vanadium oxide that does not substantially contain nitrogen, so it has excellent lubricity and the work material (difficult to cut material) due to heat generated during cutting. ) And its chips are heated at high temperature, ensuring excellent lubricity and welding resistance between the cutting edge and the work material and the chips, and the composition graded vanadium oxynitride layer Since the compositional change of oxygen (or nitrogen) along the layer thickness direction is continuous, the mechanical and chemical property changes within the layer are also continuous, like a stacked structure of different layers. There was no discontinuous change in mechanical and chemical properties The upper layer made of composition-gradient type vanadium oxynitride as a whole has excellent high-temperature strength, and the adhesiveness and reactivity of the work material and chips to the cutting edge surface are significantly reduced, resulting in high heat generation. In addition, it exhibits excellent chipping resistance in heavy cutting of difficult-to-cut materials that require high local loads on the cutting edge.

(F) The hard coating layer of (e) is, for example, an arc ion plating apparatus having a structure shown in a schematic plan view in FIG. 1A and a schematic front view in FIG. A tool base mounting rotary table is provided, and a metal V is disposed as a cathode electrode (evaporation source) on one side of the rotary table, and Cr-Y having a predetermined composition as a cathode electrode (evaporation source) on the other side. Using an arc ion plating apparatus in which an alloy is disposed, a plurality of tool bases are mounted in a ring shape along the outer peripheral portion at a predetermined distance in the radial direction from the central axis on the rotary table of the apparatus. While rotating the rotary table with the atmosphere inside the apparatus as a nitrogen atmosphere and rotating the tool base itself for the purpose of uniforming the thickness of the hard coating layer to be deposited, An arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode of the Cr—Y alloy so that the (Cr, Y) N layer as the lower layer is formed on the surface of the tool base to a target layer thickness. After vapor deposition,
The arc discharge between the cathode electrode (evaporation source) and the anode electrode of the Cr—Y alloy is stopped, and then the metal V serving as the cathode electrode (evaporation source) is kept in a nitrogen gas atmosphere in the apparatus. An arc discharge is generated between the anode electrode and first, vanadium nitride is deposited and formed.
After that, while the arc discharge between the cathode electrode (evaporation source) and the anode electrode of the metal V is continued, the atmosphere in the apparatus is changed to an oxygen-nitrogen mixed gas atmosphere, and gradually contains oxygen gas as the deposition proceeds. Vapor deposition is continued while increasing the ratio, and a composition gradient type vanadium oxynitride layer is deposited,
When the thickness of the vapor deposition layer approaches the predetermined target layer thickness, the oxygen gas content in the oxygen-nitrogen mixed gas atmosphere is further increased, and the vapor deposition layer is substantially formed on the outermost surface of the target layer thickness of vanadium oxynitride. By forming vanadium oxide containing no nitrogen in
A hard coating layer comprising a (Cr, Y) N layer as a lower layer and a composition gradient type vanadium oxynitride layer as an upper layer can be formed by vapor deposition.

(G) The coated tool formed by vapor-depositing the hard coating layer composed of the lower layer and the upper layer described above is particularly suitable for cutting difficult-to-cut materials such as Al alloy, mild steel, and stainless steel with high viscosity and adhesion. Even under heavy cutting conditions such as high depth of cut and high feed with high load, the (Cr, Y) N layer, which is the lower layer, has excellent high-temperature hardness, predetermined high-temperature strength, and lubricity. The layer is composed of a composition graded vanadium oxynitride layer having an oxygen concentration distribution structure in which the oxygen content gradually increases along the layer thickness direction, and the upper layer is superior to the lower layer by the oxygen concentration distribution structure in the upper layer. The hard coating layer consisting of the lower layer and the upper layer as a whole has excellent adhesion and bonding strength, as well as excellent lubricity and welding resistance to the work material (hard-to-cut material). ,soon It has excellent lubricity, welding resistance, excellent high-temperature strength, and wear resistance. Heavy cutting can be performed in a state where the adhesion and reactivity of difficult-to-cut materials and chips to the cutting edge surface are significantly reduced. Since it is performed, chipping is not generated at the cutting edge, and excellent wear resistance is exhibited over a long period of time.
The research results shown in (a) to (g) above were obtained.

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 1 to 5 μm, and
Cr and Y composite nitride satisfying the composition formula: (Cr _1-X Y _X ) N (where X is the Y content and the atomic ratio is 0.001 ≦ X ≦ 0.1) layer,
(B) As an upper layer, an acid having an average layer thickness of 1 to 5 μm and having an oxygen concentration distribution structure in which the oxygen content increases from the lower layer side of (a) toward the surface in the layer thickness direction. A vanadium oxynitride layer that is substantially free of oxygen at the lowermost surface of the vanadium oxynitride layer and substantially free of nitrogen at the outermost surface of the vanadium oxynitride layer;
A surface-coated cutting tool that exhibits a chipping resistance in which the hard coating layer is excellent in heavy cutting of difficult-to-cut materials, which is formed by forming the hard coating layer configured as described above in (a) and (b). "
It has the characteristics.

  Next, regarding the constituent layers of the hard coating layer of the coated tool of the present invention, the reason why the numerical values are limited as described above will be described.

A lower layer comprising a (Cr, Y) N layer;
The (Cr, Y) N constituting the lower layer has a predetermined high-temperature strength and lubricity, and has excellent high-temperature hardness due to its constituent Y component. When the indicated X value (= Y / (Cr + Y), but the atomic ratio) is less than 0.001 (atomic ratio) in the proportion of the total amount with Cr, the predetermined high-temperature hardness cannot be secured, This causes a decrease in wear resistance. On the other hand, if the X value indicating the ratio of Y exceeds 0.10 (atomic ratio), the Cr content decreases relatively, which is necessary for heavy cutting of difficult-to-cut materials. The X value is determined to be 0.001 to 0.10 (atomic ratio) because not only the high-temperature strength that can be achieved cannot be ensured but also the lubricity is lowered and it becomes difficult to prevent the occurrence of chipping. It was.
Further, if the average layer thickness is less than 1 μm, it is insufficient to exhibit its excellent wear resistance over a long period of time, whereas if the average layer thickness exceeds 5 μm, the above-mentioned high viscosity is difficult. In the heavy cutting of the cutting material, chipping is likely to occur at the cutting edge, so the average layer thickness was set to 1 to 5 μm.

A compositionally graded upper layer comprising a vanadium oxynitride layer (VNO layer);
The composition-graded vanadium oxynitride layer (VNO layer) that forms the upper layer of the hard coating layer has different oxygen (nitrogen) content along the layer thickness direction, so its characteristics are also oxygen (nitrogen) content. Vanadium nitride that does not substantially contain oxygen is formed near the surface of the lower layer (the lowermost surface of the upper layer). The adhesion strength is also high. On the other hand, on the surface (near) of the upper layer, the vanadium oxide substantially containing no nitrogen (that is, the N content ratio N / (N + O) in the total amount with O is an atomic ratio). (Less than 0.1 vanadium oxide), it has excellent lubricity and welding resistance, and has extremely low adhesion and reactivity to work materials (hard-to-cut materials) and chips. State where the work material is heated at high temperature during cutting From being maintained without also changes, which is the lower layer (Cr, Y) to protect the N layer from the high temperature heated workpiece and chips, it exerts an action to suppress this chipping occurred.
In the present invention, “the lowermost surface of the vanadium oxynitride layer does not substantially contain oxygen” or “near the surface of the lower layer (the lowermost surface of the upper layer) substantially contains oxygen. `` No vanadium nitride '' means that the oxygen content is measured in a region having a measurement width of 0.1 to 0.2 μm on the upper layer side from the interface between the upper layer and the lower layer in the lowermost region of the upper layer adjacent to the lower layer. When measured, the oxygen content detected in the region (that is, the ratio of O content to the total content with N content (= O / (N + O), where the atomic ratio) is 0.1 or less. In addition, “the vanadium oxynitride layer is substantially free of nitrogen” or “the vanadium oxide substantially free of nitrogen is present on the surface of the upper layer (nearly)” Measured when measuring the oxygen content of the upper layer surface. Oxygen content (i.e., the ratio of O content relative to the total amount of the N content (= O / (N + O), provided that means that atomic ratio) is 0.9 or more.
Also, if the average layer thickness of the upper layer is less than 1 μm, even if the upper layer is provided, improvement in lubricity and welding resistance cannot be expected, while if the average layer thickness exceeds 5 μm and becomes too thick. Since the chipping tends to occur, the average layer thickness is set to 1 to 5 μm.

  In the coated tool of the present invention, the lower layer (Cr, Y) N layer constituting the hard coating layer has excellent high-temperature hardness, predetermined high-temperature strength and lubricity, and compositionally graded vanadium oxynitride Since the upper layer consisting of layers combines excellent lubricity (surface slipperiness), welding resistance, and high-temperature strength, the hard coating layer as a whole is excellent in addition to excellent high-temperature hardness and high-temperature strength. It has lubricity and adhesion resistance, and as a result, it generates heavy heat from difficult-to-cut materials such as Al alloy, mild steel, and stainless steel, which are particularly viscous and sticky. Even so, it exhibits excellent chipping resistance and exhibits excellent wear resistance over a long period of time.

  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, and after sintering, tool bases A-1 to A-10 made of WC-based cemented carbide with ISO standard / CNMG120408 chip shape 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 Then, the green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, a tool base B made of TiCN-based cermet having an ISO standard / CNMG120408 chip shape was obtained. -1 to B-6 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 predetermined distance in the radial direction from the central axis on the rotary table in the apparatus, cathode electrodes (evaporation sources) are arranged on opposite sides across the rotary table, one of which Is arranged with a metal V as a cathode electrode (evaporation source), and a Cr-Y alloy for forming a lower layer having a predetermined composition as a cathode electrode (evaporation source) on the other side.
(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 an arc discharge is generated by flowing a current of 100 A between the cathode electrode Cr-Y alloy for forming the lower layer and the anode electrode, whereby the tool base surface is made of the Cr-Y alloy. Bombard washed,
(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 Cr—Y alloy of the cathode electrode and the anode electrode, and the target composition and the lower part of the target layer thickness shown in Tables 3 and 4 are formed on the surface of the tool base. After the (Cr, Y) N layer as a layer is deposited with an average layer thickness of 1 to 5 μm, the arc discharge between the cathode electrode (evaporation source) and the anode electrode of the Cr—Y alloy is stopped,
(D) Then, with the atmosphere in the apparatus kept in a nitrogen gas atmosphere, an arc discharge was generated between the metal V as the cathode electrode (evaporation source) and the anode electrode, and first, vanadium nitride was deposited and formed.
(E) Thereafter, the arc atmosphere between the cathode electrode (evaporation source) of the metal V and the anode electrode is continued, the atmosphere in the apparatus is changed to an oxygen-nitrogen mixed gas atmosphere, and gradually, as the deposition proceeds. Vapor deposition is continued while increasing the oxygen gas content ratio, and a composition gradient type vanadium oxynitride layer is deposited,
(F) When the thickness of the vapor deposition layer approaches the predetermined target layer thickness, the oxygen gas content in the oxygen-nitrogen mixed gas atmosphere is further increased, and vapor deposition is performed on the outermost surface of the target layer thickness of vanadium oxynitride. Vanadium oxide substantially free of nitrogen (the value of O / (N + O) depending on the atomic ratio at the surface is 0.9 or more) is formed, and the vanadium oxynitride layer having the target layer thickness shown in Tables 3 and 4 After vapor-depositing, the arc discharge between the metal V and the anode electrode is stopped,
According to the above (a) to (f), a hard coating layer composed of a (Cr, Y) N layer as a lower layer and a composition gradient type vanadium oxynitride layer as an upper layer is formed by vapor deposition. The surface-coated throwaway tips (hereinafter referred to as the present-coated tips) 1 to 16 of the present invention were produced.

  For comparison purposes, these tool bases A-1 to A-10 and B-1 to B-6 were ultrasonically cleaned in acetone and dried, respectively, and the arc ion plating shown in FIG. The device was charged and a Cr—Y alloy having a predetermined composition was attached as a cathode electrode (evaporation source). First, the inside of the device was evacuated and kept at a vacuum of 0.1 Pa or less, and the inside of the device was 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 Cr-Y alloy of the cathode electrode and the anode electrode. Was bombarded with the Cr-Y alloy, nitrogen gas was introduced into the apparatus as a reaction gas to make a reaction atmosphere of 3 Pa, and a bias voltage applied to the tool base was -100 V An arc discharge is generated between the cathode electrode and the anode electrode having the predetermined composition, and the surface of each of the tool bases A-1 to A-10 and B-1 to B-6 is formed on the surface of Table 5 A surface-coated throwaway tip (hereinafter referred to as a comparative coated tip) as a comparative coating tool is formed by vapor-depositing a hard coating layer composed of a (Cr, Y) N layer having a target composition and a target layer thickness shown in Table 6. 1 to 16 were produced.

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 A5083 lengthwise equidistant four round grooved round bars,
Cutting speed: 800 m / min. ,
Cutting depth: 4.0 mm,
Feed: 1.0 mm / rev. ,
Cutting time: 10 minutes,
Of the aluminum alloy under the above conditions (cutting condition A), a dry intermittent high cutting test (normal cutting is 1.0 mm),
Work material: JIS / S11C round bar,
Cutting speed: 235 m / min. ,
Cutting depth: 3 mm,
Feed: 0.5 mm / rev. ,
Cutting time: 5 minutes,
Dry continuous high-cut cutting test of mild steel under the above conditions (cutting condition B) (normal cutting is 1.5 mm),
Work material: JIS / SUS304 lengthwise equidistant four round grooved round bars,
Cutting speed: 240 m / min. ,
Incision: 2 mm,
Feed: 0.5 mm / rev. ,
Cutting time: 10 minutes,
Was performed in a dry interrupted high feed cutting test (normal feed is 0.25 mm / rev.), And the flank wear width of the cutting edge was measured in any cutting test. did. The measurement results are shown in Tables 7 and 8.

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 .8 μm Co powder was prepared, each of these raw material powders was blended in the blending composition shown in Table 9, and then added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and then pressed into a predetermined shape 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 Then, three types of round rod sintered bodies for forming a tool base having diameters of 8 mm, 13 mm, and 26 mm were formed, and further, the three types of round rod sintered bodies were ground by grinding as shown in Table 9. 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 (Cr, Y) N layer having the target composition and target layer thickness shown in Table 10 and the target layer thickness also shown in Table 10 and O at the atomic ratio on the layer surface. The surface coating cemented carbide end mill (hereinafter referred to as the present invention) as a coated tool of the present invention is formed by vapor-depositing a hard coating layer composed of a composition gradient type vanadium oxynitride layer having a value of / (N + O) of 0.9 or more. Invention-coated end mills) 1 to 16 were produced.

  For the purpose of comparison, the surfaces of the tool bases (end mills) C-1 to C-8 are ultrasonically cleaned in acetone and dried, and then mounted on the arc ion plating apparatus shown in FIG. Then, under the same conditions as in Example 1, a hard coating layer composed of a (Cr, Y) N layer having the target composition and target layer thickness shown in Table 11 is vapor-deposited, so that the surface coating as a conventional coating tool is performed. Carbide end mills (hereinafter referred to as comparative coated end mills) 1 to 8 were produced.

Next, of the present invention coated end mills 1-16 and comparative coated end mills 1-8,
For the present coated end mills 1-6 and comparative coated end mills 1-3,
Work material-Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS A5083 plate material,
Cutting speed: 300 m / min. ,
Groove depth (cut): 15 mm,
Table feed: 700 mm / min,
Aluminum alloy dry-type high-groove grooving test (normal groove depth is 10 mm),
For the inventive coated end mills 7-12 and comparative coated end mills 4-6,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / S11C plate,
Cutting speed: 40 m / min. ,
Groove depth (cut): 12 mm,
Table feed: 150 mm / min,
Dry high-feed groove cutting test of mild steel under normal conditions (normal table feed is 100 mm / min),
About this invention coated end mills 13-16 and comparative coated end mills 7 and 8,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 50 m / min. ,
Groove depth (cut): 4 mm,
Table feed: 230 mm / min,
Stainless steel dry-type high-grooving groove cutting test (normal groove depth is 3 mm),
In each 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 Table 10 and Table 11, 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. The (Cr, Y) N layer having the target composition and target layer thickness shown in Table 12 and the target layer thickness and layer surface also shown in Table 12 under the same conditions as in Example 1 above. The surface coating cemented carbide of the present invention as a coated tool of the present invention is formed by vapor-depositing a hard coating layer composed of a composition-graded vanadium oxynitride layer having an atomic ratio of O / (N + O) of 0.9 or more. Drills (hereinafter referred to as the present invention-coated drills) 1 to 16 were produced.

  For the purpose of comparison, the surface of the tool base (drill) D-1 to D-8 is subjected to honing, ultrasonically cleaned in acetone and dried, and the arc ions shown in FIG. By charging the plating apparatus and depositing a hard coating layer composed of a (Cr, Y) N layer having the target composition and target layer thickness shown in Table 13 under the same conditions as in Example 1 above, 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 1-16 and comparative coated drills 1-8, for the present invention coated drills 1-6 and comparative coated drills 1-3,
Work material-Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS A5083 plate material,
Cutting speed: 160 m / min. ,
Feed: 0.8 mm / rev,
Hole depth: 6 mm,
Wet high feed drilling machining test of aluminum alloy under the conditions (normal feed is 0.4 mm / rev),
About this invention coated drills 7-12 and comparative coated drills 4-6,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / S11C plate,
Cutting speed: 40 m / min. ,
Feed: 0.35 mm / rev,
Hole depth: 7 mm,
Wet high-feed drilling test of mild steel under normal conditions (normal feed is 0.2 mm / rev),
About this invention covering drills 13-16 and comparative covering drills 7 and 8,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 100 m / min. ,
Feed: 0.4 mm / rev,
Hole depth: 10 mm,
Stainless steel wet high feed drilling cutting test under normal conditions (normal feed is 0.2 mm / rev),
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.

  (Cr, Y) N layer (this constitutes the hard coating layer of the present coated chips 1 to 32, the present coated end mills 1 to 16, and the present coated drills 1 to 16 as the present coated tool obtained as a result. The composition of the lower layer) and the composition of the hard coating layer comprising the (Cr, Y) N layers of the comparative coating tips 1 to 16, the comparative coating end mills 1 to 8 and the comparative coating drills 1 to 8 as the comparative coating tool. When measured by energy dispersive X-ray analysis using a transmission electron microscope, each showed substantially the same composition as the target composition.

  Further, for the composition gradient type vanadium oxynitride layer constituting the upper layer of the hard coating layer of the coated tool of the present invention, the area of the lowermost surface of the upper layer is measured by the Auger electron spectroscopic analysis on the cross-section polished surface of the hard coating layer. When the oxygen content was measured at 0.1 to 0.2 μm, the oxygen content detected in the region (that is, the ratio of O content to the total content with N content by atomic ratio (= O / ( N + O)) was 0.1 or less, and it was confirmed that the lowermost surface of the upper layer was composed of substantially vanadium nitride containing no oxygen. When the oxygen content on the outermost surface of the layer was measured, the ratio of O content to the total content with N content by atomic ratio (= O / (N + O)) was 0.9 or more in all cases, and the upper layer The outermost surface of the substrate substantially contains nitrogen. It was confirmed that are formed in the vanadium oxide does not.

  Moreover, when the average layer thickness of each layer which comprises said hard coating layer was cross-sectional measured using the scanning electron microscope, all showed the substantially same average value (average value of five places) as target layer thickness. .

  From the results shown in Tables 7, 8, and 10-13, the coated tools of the present invention are particularly heavy, such as high cuts and high feeds of difficult-to-cut materials such as Al alloys, mild steel, and stainless steel, which are particularly highly viscous and sticky. Even in cutting under the cutting conditions, the (Cr, Y) N layer, which is the lower layer of the hard coating layer, has excellent high-temperature hardness, high-temperature strength, and predetermined lubricity in a state where it is tightly bonded to the tool base surface. And the upper layer composed of the composition-gradient type vanadium oxynitride layer maintains the strength of the upper layer itself and the adhesion strength with the lower layer, and is excellent between the work material and the chips. As the lubricity and welding resistance are ensured, chipping does not occur and excellent wear resistance is demonstrated over a long period of time, whereas the hard coating layer is composed of (Cr, Y) N layers. A composition graded vanadium oxynitride layer In the comparative coated tools that are not used, the heavy cutting of the difficult-to-cut material further increases the adhesiveness and reactivity between the work material (hard-to-cut material) and chips and the hard coating layer. It is clear that chipping occurs at the blade and the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention exhibits excellent chipping resistance not only for cutting of general steel and ordinary cast iron, but particularly for heavy cutting of the above difficult-to-cut materials, and for a long time. Since it shows excellent cutting performance, it can fully satisfactorily cope with the FA of the cutting apparatus, labor saving and energy saving of cutting, and cost reduction.

The arc ion plating apparatus used for forming the hard coating layer which comprises this invention coated tool is shown, (a) is a schematic plan view, (b) is a schematic front view. It is a schematic explanatory drawing of the conventional arc ion plating apparatus used in forming the hard coating layer which comprises a comparative coating tool.

Claims (1)

On the surface of the tool base composed of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) The lower layer has an average layer thickness of 1 to 5 μm, and
Cr and Y composite nitride satisfying the composition formula: (Cr _1-X Y _X ) N (where X is the Y content and the atomic ratio is 0.001 ≦ X ≦ 0.1) layer,
(B) As an upper layer, an acid having an average layer thickness of 1 to 5 μm and having an oxygen concentration distribution structure in which the oxygen content increases from the lower layer side of (a) toward the surface in the layer thickness direction. A vanadium oxynitride layer that is substantially free of oxygen at the lowermost surface of the vanadium oxynitride layer and substantially free of nitrogen at the outermost surface of the vanadium oxynitride layer;
A surface-coated cutting tool that exhibits a chipping resistance in which the hard coating layer is excellent in heavy cutting of difficult-to-cut materials, which is formed by forming the hard coating layer configured as described above in (a) and (b).

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