JP2009119550A - Surface coated cutting tool with excellent chipping resistance due to hard coating layer - Google Patents

Abstract

Provided is a surface-coated cutting tool that exhibits excellent chipping resistance with a hard coating layer in high-speed cutting of a work material that is easy to cause welding with low hardness.
The surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet has an average layer thickness of 1 to 5 μm, and has a composition formula: (Cr _1- XY _X ) A surface-coated cutting tool formed by forming a hard coating layer composed of a composite nitride layer of Cr and Y that satisfies N (provided that the atomic ratio is 0.01 ≦ X ≦ 0.1).
[Selection figure] None

Description

  The present invention has an excellent hard coating layer especially when a work material having a low hardness, such as a copper alloy or carbon steel, which is easy to weld chips to the cutting edge, is cut under high-speed cutting conditions. The present invention relates to a surface-coated cutting tool that exhibits chipping resistance (hereinafter referred to as a coated tool).

  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.

  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. A coating tool formed by physical vapor deposition of a hard coating layer as a layer is known, and this CrN layer is known to have excellent lubricity.

Then, the CrN layer of the above-mentioned conventional coated tool is charged with, for example, an arc ion plating apparatus which is one type of physical vapor deposition apparatus shown schematically in FIG. An arc discharge is generated between the cathode electrode (evaporation source) on which the Cr alloy is set and the anode electrode, for example, at a current of 90 A, and at the same time, nitrogen gas is used as a reaction gas in the apparatus. It is also known that the CrN layer can be formed as a hard coating layer by vapor deposition under the condition that a bias voltage of, for example, −100 V is applied, for example, to a reaction atmosphere of 2 Pa. Yes.
Japanese Patent Laid-Open No. 11-156992

  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. However, in the above-mentioned conventional coated tools, this is a low hardness such as copper alloy, carbon steel, etc. When used for high-speed cutting of work materials that are easily welded to the tool surface, the work material and chips are heated to a high temperature due to the heat generated during cutting, and the viscosity increases further. The adhesion and reactivity to the surface of the layer have further increased, and as a result, the occurrence of chipping (slight chipping) at the cutting edge part has increased rapidly, and this has led to a service life in a relatively short time. is there

In view of the above, the inventors of the present invention, especially when cutting a low-hardness workpiece material that easily adheres to the tool surface, such as a copper alloy or carbon steel, is performed under high-speed cutting conditions. In order to develop a coated tool that exhibits excellent chipping resistance with a hard coating layer, as a result of conducting research while focusing on the above-mentioned conventional coated tool,
When 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 1 to 10 atomic%, and the (Cr, Y) N layer is configured. Because the heat resistance of the (Cr, Y) N layer is improved by the inclusion of the Y component, high heat is generated during cutting in the cutting of work materials that have low hardness and are easily welded to the tool surface, such as copper alloys and carbon steel. Even if this occurs, the occurrence of welding at the cutting edge is suppressed, and the lubricity of the (Cr, Y) N layer is not deteriorated. As a result, the occurrence of chipping (small chipping) at the cutting edge is prevented. The present invention has been found and the present invention has been achieved.

This invention
"On the surface of the tool base made of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) having an average layer thickness of 1-5 μm, and
Composite nitride of Cr and Y satisfying the composition formula: (Cr _1-X Y _X ) N (where X is the Y content and the atomic ratio is 0.01 ≦ X ≦ 0.1) A surface-coated cutting tool in which a hard coating layer composed of layers is formed. "
It has the characteristics.

  Next, the present invention will be described in detail.

  The composite nitride of Cr and Y (hereinafter abbreviated as (Cr, Y) N) constituting the hard coating layer has predetermined high-temperature hardness, high-temperature strength, and lubricity, and Y, which is a constituent component thereof. Depending on the component, it will have excellent heat resistance, so that it will maintain a low coefficient of friction even under high temperature cutting conditions and will exhibit excellent lubricity, but the X value indicating the Y content is Cr and When the ratio (atomic ratio, the same applies hereinafter) in the total amount of less than 0.01, heat resistance cannot be ensured and a lubricating effect cannot be expected, while the X value indicating the ratio of Y When the ratio exceeds 0.10, the Cr content ratio is relatively reduced, and not only the high-temperature strength required for high-speed cutting of a work material having low hardness and high weldability cannot be secured. Reduce lubricity and prevent chipping From becoming difficult, defining the X value 0.01 to 0.10 (atomic ratio, hereinafter the same) and.

  If the average layer thickness of the (Cr, Y) N layer constituting the hard coating layer is less than 1 μm, it is not sufficient to exhibit its excellent heat resistance and lubricity over a long period of time. If the thickness exceeds 5 μm, chipping is likely to occur at the cutting edge in high-speed cutting of work materials with low hardness and high weldability, such as copper alloys and carbon steel, so the average layer thickness is 1 to 5 μm. It was determined.

Then, the (Cr, Y) N layer is, for example, charged in an arc ion plating apparatus which is one type of physical vapor deposition apparatus schematically shown in FIG. An arc discharge is generated between the cathode electrode (evaporation source) on which a Cr—Y alloy having a predetermined composition is set and the anode electrode, for example, at a current of 90 A, while being heated to a temperature of ℃. Nitrogen gas is introduced as a reaction gas to form a reaction atmosphere of, for example, 2 Pa. On the other hand, the (Cr, Y) N layer is hardened on the substrate by vapor deposition under a condition of applying a bias voltage of, for example, −100 V. It can be formed as a coating layer.

  In the coated tool of the present invention, the (Cr, Y) N layer constituting the hard coating layer has excellent high-temperature hardness and high-temperature strength, and further excellent heat resistance and lubricity. Even when cutting work materials such as copper alloy and carbon steel with high weldability to the cutting edge under high-speed cutting conditions with large heat generation, they exhibit excellent lubricity and chipping resistance. It exhibits excellent wear resistance over a wide range.

  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. The tool base is inserted into the apparatus, and a Cr-Y alloy for forming a hard coating layer having a predetermined composition and an anode electrode are disposed as a cathode electrode (evaporation source) in the apparatus.
(B) First, the inside of the apparatus was heated to 500 ° C. with a heater while the inside of the apparatus was evacuated and maintained at a vacuum of 0.1 Pa or less, and then a −1000 V DC bias voltage was applied to the tool base, and the cathode A current of 100 A is passed between the Cr-Y alloy of the electrode and the anode electrode to generate an arc discharge, and the tool base surface is bombarded,
(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, and the Cr—Y alloy of the cathode electrode and An arc discharge is generated by flowing a current of 120 A between the anode electrode and a hard coating layer comprising a (Cr, Y) N layer having a target composition and a target layer thickness shown in Table 3 on the surface of the tool base. Vapor deposition with an average layer thickness of 1-5 μm,
By the said (a)-(c), this invention surface covering throwaway tip (henceforth this invention coating tip) 1-16 as a this invention coating tool was manufactured, respectively.

  For comparison purposes, these tool bases A-1 to A-10 and B-1 to B-6 are ultrasonically cleaned in acetone and dried, and then the arc ion plating apparatus shown in FIG. After mounting the metal Cr as a cathode electrode (evaporation source), the apparatus was first heated to 500 ° C. with a heater while evacuating the apparatus and maintaining a vacuum of 0.1 Pa or less. A DC bias voltage of −1000 V is applied to the tool base, and a current of 100 A is applied between the metal Cr and the anode of the cathode electrode to generate an arc discharge, thereby cleaning the surface of the tool base by bombarding. Nitrogen gas as a reaction gas is introduced to form a reaction atmosphere of 3 Pa, and the bias voltage applied to the tool base is lowered to -100 V, so that the cathode electrode and the anode of the metal Cr are Arc discharge is generated between the electrodes and the tool bases A-1 to A-10 and B-1 to B-6 on the respective surfaces of chromium nitride (CrN) having a target layer thickness shown in Table 4. Surface-coated throwaway tips (hereinafter referred to as comparative coated tips) 1 to 16 as comparative coated tools were produced by vapor-depositing hard coating layers composed of layers.

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 / S45C round bar,
Cutting speed: 270 m / min. ,
Cutting depth: 2.0 mm,
Feed: 0.30 mm / rev. ,
Cutting time: 5 minutes,
Dry continuous high-speed cutting test of carbon steel under the conditions (cutting condition A) (normal cutting speed is 150 m / min.),
Work material: JIS C1100 round bar,
Cutting speed: 240 m / min. ,
Cutting depth: 2.0 mm,
Feed: 0.20 mm / rev. ,
Cutting time: 5 minutes,
Dry continuous high-speed cutting test of copper alloy under the conditions (cutting condition B) (normal cutting speed is 120 m / min.),
Work material: JIS / S10C round bar,
Cutting speed: 250 m / min. ,
Cutting depth: 2.0 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 5 minutes,
Dry continuous high-speed cutting test of mild steel under the conditions (cutting condition C) (normal cutting speed is 130 m / min.),
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 5.

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 powders were prepared, each of these raw material powders was blended in the composition shown in Table 6, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and then shaped 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 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 types of round bar sintered bodies are shown in Table 6 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. By superposing the hard coating layer consisting of the (Cr, Y) N layer having the target composition and the target layer thickness shown in Table 7 under the same conditions as in Example 1, the surface coating superconductor of the present invention as the coating tool of the present invention is formed. Hard end mills (hereinafter referred to as the present invention coated end mills) 1 to 8 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, by depositing a hard coating layer composed of a CrN layer having a target layer thickness shown in Table 7 under the same conditions as in Example 1 above, a surface coated carbide end mill as a conventional coated tool (hereinafter, comparison) 1 to 8 were produced.

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 / S45C plate,
Cutting speed: 60 m / min. ,
Groove depth (cut): 3 mm,
Table feed: 250 mm / min,
Dry high-speed grooving test of carbon steel under the conditions (normal cutting speed is 30 m / min.),
About this invention coated end mills 4-6 and comparative coated end mills 4-6,
Work material-planar dimensions: 100 mm x 250 mm, thickness: 50 mm JIS C1100 plate material,
Cutting speed: 50 m / min. ,
Groove depth (cut): 3.5 mm,
Table feed: 200 mm / min,
A dry high-speed grooving test of a copper alloy under the conditions (normal cutting speed is 30 m / min.),
For the coated end mills 7 and 8 and the comparative coated end mills 7 and 8 of the present invention,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / S10C plate,
Cutting speed: 50 m / min. ,
Groove depth (cut): 3.5 mm,
Table feed: 230 mm / min,
A dry high-speed grooving test of mild steel under the conditions (normal cutting speed is 30 m / min.),
In each groove cutting test, the cutting groove length was measured until the flank wear width of the outer peripheral blade of the cutting edge portion reached 0.1 mm, which is a guide for the service life. The measurement results are shown in Table 7, 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. As a coated tool of the present invention, a hard coating layer composed of a (Cr, Y) N layer having a target composition and a target layer thickness shown in Table 8 is formed by vapor deposition under the same conditions as in Example 1 above. The surface-coated carbide drills (hereinafter referred to as the present invention-coated drills) 1 to 8 of the present invention were produced.

  For comparison purposes, 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 ions shown in FIG. By superposing the surface coating as a comparative coating tool by depositing in a plating apparatus and depositing a hard coating layer composed of a CrN layer having the target layer thickness shown in Table 8 under the same conditions as in Example 1 above. Hard drills (hereinafter referred to as comparative coated drills) 1 to 8 were produced.

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 / S45C plate,
Cutting speed: 80 m / min. ,
Feed: 0.4 mm / rev,
Hole depth: 8 mm,
Wet high-speed drilling test of carbon steel under the conditions (normal cutting speed is 50 m / min.),
About this invention coated drill 4-6 and comparative coated drill 4-6,
Work material-planar dimensions: 100 mm x 250 mm, thickness: 50 mm JIS C1100 plate material,
Cutting speed: 70 m / min. ,
Feed: 0.35 mm / rev,
Hole depth: 8 mm,
Wet high-speed drilling test of copper alloy under the conditions (normal cutting speed is 40 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 / S10C plate,
Cutting speed: 45 m / min. ,
Feed: 0.2 mm / rev,
Hole depth: 7 mm,
Wet high-speed drilling machining test of mild steel under the conditions (normal cutting speed is 30 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 Table 8, respectively.

  As a result of the present invention coated tool, the present coated chips 1 to 16, the present coated end mills 1 to 8, and the (Cr, Y) N layer of the hard coating layer of the present coated drill 1 to 8 When the composition was measured by energy dispersive X-ray analysis using a transmission electron microscope, it showed substantially the same composition as the target composition.

  Moreover, when the cross-sectional measurement was carried out using the scanning electron microscope for the average layer thickness of the hard coating layer of this invention coating tool and a comparison coating tool, all were the average value (average value of five places) substantially the same as target layer thickness. showed that.

  From the results shown in Tables 5, 7, and 8, the coated tool of the present invention performs cutting of a work material having a low hardness, such as a copper alloy and carbon steel, which easily adheres to the tool surface, under high-speed cutting conditions. Even in this case, the hard coating layer made of the (Cr, Y) N layer has heat resistance and excellent lubricity, so that it exhibits excellent wear resistance over a long period of time without occurrence of chipping. In the comparative coated tool in which the hard coating layer is composed of the CrN layer, the adhesion and reactivity between the work material and the chips and the hard coating layer are further increased, while the lubricity is lowered. In addition, it is clear that chipping occurs at the cutting edge and the service life is reached in a relatively short time.

  As described above, the coated tool according to the present invention is not only for cutting of general steel and ordinary cast iron, but particularly for high-speed work materials that have low hardness such as copper alloy and carbon steel and are easily welded to the tool surface. Even in cutting, it exhibits excellent lubricity and exhibits excellent cutting performance over a long period of time, so it is sufficient for FA of cutting equipment, labor saving and energy saving of cutting, and further cost reduction It can respond to satisfaction.

It is a schematic explanatory drawing of the arc ion plating apparatus used in forming the hard coating layer which comprises a coating tool.

Claims (1)

On the surface of the tool substrate made of tungsten carbide based cemented carbide or titanium carbonitride based cermet, and having an average layer thickness of 1 to 5 μm, and
Composition formula: (Cr _1-X Y _X ) N (where X represents the content ratio of Y, and is an atomic ratio, 0.01 ≦ X ≦ 0.1)
A surface-coated cutting tool in which a hard coating layer composed of a composite nitride layer of Cr and Y that satisfies the above conditions is formed.

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