JP2018164961A - Surface coat cutting tool by which hard coating layer exhibits excellent wear resistance and chipping resistance and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating tool that is excellently tough even if subjected to high speed feed and that exhibits excellent chipping resistance and wear resistance for a long time of use.SOLUTION: A surface coat cutting tool is provided with a hard coating layer on a surface of a tool base body such that: (a) a hard coat layer includes, in a ridge line part, (TiAl)(CN)(60≤x≤0.95, 0≤y≤0.005) with a layer thickness of 1 to 20 μm; (b) the hard coat layer has a columnar structure and includes at least a phase having a face-centered cubic structure of NaCl type; and (c) the hard coat layer decreases in film thickness with respect to the layer thickness of the ridge line part such that the layer thickness of a part extending 200 μm toward a cutting face from the ridge line part is in the range of 30% to 95%, and the layer thickness of a part extending 200 μm toward a flank from the ridge line part is in the range of 30% to 95%.SELECTED DRAWING: Figure 1

Description

In this invention, when carbon steel, alloy steel, cast iron, etc. are cut with high heat generation and high load acting on the cutting edge with high heat, the hard coating layer has excellent chipping resistance, The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent wear resistance after use.

Conventionally, for the purpose of improving the cutting performance of cutting tools, tungsten carbide (hereinafter referred to as WC) based cemented carbide, titanium carbonitride (hereinafter referred to as TiCN) based cermet or cubic boron nitride (hereinafter referred to as cBN). ) A coated tool in which a Ti-Al based composite nitride layer is formed as a hard coating layer on the surface of a substrate (hereinafter collectively referred to as a substrate) composed of a super-high pressure sintered body by vapor deposition. These are known to exhibit excellent wear resistance.
Although the conventional coated tool formed by coating the conventional Ti-Al based composite nitride layer is relatively excellent in wear resistance, it is hard to cause abnormal wear such as chipping when used under high-speed cutting conditions. Various proposals for improving the coating layer have been made.

For example, Patent Document 1 _consists of _{Ti 1-x Al x N,} Ti 1-xA l x C, and / or _Ti 1-x _Al x CN (wherein, 0.65 ≦ x ≦ 0.9) A coated tool is described in which the outer layer has a compressive stress in the range of 100-1100 MPa, and a TiCN layer or an Al ₂ O ₃ layer is disposed below this outer layer.

Special table 2011-513594 gazette

In recent years, there has been a strong demand for energy saving and energy saving in cutting, and along with this, cutting has become a trend toward higher speed, higher feed and higher efficiency. Further, abnormal damage resistance such as chipping resistance, chipping resistance, and peeling resistance is required, and excellent wear resistance is required for long-term use.
However, in the coated tool described in Patent Document 1, the film thickness distribution of the hard coating layer is not taken into consideration, and abnormalities such as chipping associated with processing that requires more wear resistance and micro peeling of the hard coating layer are considered. The tool life could be reached early due to damage.

  Therefore, the present invention has excellent toughness and excellent chipping resistance and wear resistance over a long period of use even when subjected to high-speed high-feed cutting such as carbon steel, cast iron, and alloy steel. An object of the present invention is to provide a coated tool.

The present inventors have at least a composite nitride or composite carbonitride of Ti and Al (hereinafter sometimes referred to as “TiAlCN” or “(Ti _1−x Al _x ) (C _y N _1−y )”). As a result of diligent research to improve the wear resistance and chipping resistance of the coated tool in which the hard coating layer containing the material is formed, the following knowledge was obtained.

  That is, an increase in the thickness of the local hard coating layer in the vicinity of the ridge line portion is suppressed, and the layer thickness of the 200 μm portion is increased from the ridge line portion toward the flank side and the rake face side, respectively. ), The wear resistance is improved by gradually decreasing the film thickness so that it is in the range of 30 to 95%, preferably 40 to 90%. It has been found that abnormal damage such as chipping is suppressed, and as a result, tool life is improved.

  Furthermore, by performing processing such as blasting after film formation by thermal CVD, the increase in the film thickness of the hard coating layer is more reliably suppressed, and the film of the ridge line part from the ridge line part toward the flank and rake face It has also been found that the film thickness can be gradually decreased so as to be in the range of 30 to 95%, preferably 40 to 90% with respect to the thickness.

The present invention has been made based on the above findings,
“(1) In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base composed of either a WC cemented carbide, a TiCN-based cermet, or a cBN-based ultrahigh-pressure sintered body,
(A) The hard coating layer includes at least a composite nitride or composite carbonitride layer of Ti and Al having a ridge line thickness of 1 to 20 μm, and has a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the average content x of Ti in the total amount of Ti and Al in the composite nitride or composite carbonitride layer, and the average content of C in the total amount of C and N ( However, x and y are both atomic ratios) satisfy 0.60 ≦ x ≦ 0.95 and 0 ≦ y ≦ 0.005, respectively.
(B) The hard coating layer includes a columnar structure and includes at least a phase of a composite nitride or composite carbonitride of Ti and Al having a NaCl-type face-centered cubic structure,
(C) The hard coating layer has a layer thickness in the range of 30% to 95% from the ridge line part to the rake face side to the rake line part from the ridge line part to the flank side and 200 μm from the ridge line part to the flank side. A surface-coated cutting tool characterized in that the film thickness is gradually reduced so that the layer thickness in each of the points is within a range of 30% to 95%.
(2) With respect to the layer thickness of the ridge line portion, the layer thickness at the location of 200 μm from the ridge line portion to the rake face side is in the range of 40% to 90%, and the layer thickness at the location of 200 μm from the ridge line portion to the flank side. Is in a range of 40% to 90%, the surface-coated cutting tool according to (1).
(3) In the cross section of the composite nitride layer in the direction perpendicular to the tool substrate, the area ratio occupied by the composite nitride or composite carbonitride of Ti and Al having a NaCl type face centered cubic structure is 70% or more. The surface-coated cutting tool according to (1) or (2), wherein
(4) At least one of an Al oxide layer or a nitride layer, or a Ti nitride layer, a carbide layer, a carbonitride layer, a carbonate layer, and a carbonitride layer on the hard coating layer. The surface-coated cutting tool according to any one of (1) to (3), wherein one layer or two or more layers are formed with a total layer thickness of 1 to 25 μm.
(5) One or more Ti compound layers of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer between the tool base and the hard coating layer The surface-coated cutting tool according to any one of (1) to (4), wherein a lower layer having a total average layer thickness of 0.1 to 20 μm is present. Is.

The present invention has outstanding wear resistance even in high-speed and high-feed machining, and is capable of prolonging the tool life by suppressing abnormal damage such as chipping caused by minute falling off or peeling of the hard coating layer. It has a great effect.
In other words, on the flank side where the work material flows, chipping is likely to occur along with the detachment of the product present at the interface between the tool and the work material, but chipping is caused by making the layer thickness thinner than the ridge line part. On the other hand, on the rake face side where chips generated by cutting flow, film detachment is likely to occur due to scraping with the chips, but abnormal damage is caused by making the layer thickness thinner than the ridgeline part. Can be suppressed.

It is a cross-sectional schematic diagram of the coated tool of this invention.

  Next, the hard coating layer of the coated tool of the present invention will be described in more detail.

Composite carbonitride layer of Ti and _{Al ((Ti 1-x Al} x) (C y N 1-y)) the average composition the composite carbonitride layer of the composition _{formula: (Ti 1-x Al x} ) ( C _y N _1-y ), the average content ratio x in the total amount of Ti and Al in Al and the average content ratio y in the total amount of C and N in C (where x and y are In either case, the ratio of the number of atoms) controls the composition so as to satisfy 0.60 ≦ x ≦ 0.95 and 0 ≦ y ≦ 0.005, respectively.
The reason is that if the average content ratio x of Al is less than 0.60, the (Ti _1-x Al _x ) (C _y N _1-y ) layer is inferior in oxidation resistance, and high-speed, high-feed such as alloy steel If the average content ratio x of Al exceeds 0.95, the amount of hexagonal crystals inferior in hardness increases and the hardness decreases. Wear resistance is reduced. Therefore, the average content ratio x of Al was determined to be 0.60 ≦ x ≦ 0.95.
Further, when the average content y of the C component contained in the (Ti _1-x Al _x ) (C _y N _1-y ) layer is a small amount in the range of 0 ≦ y ≦ 0.005, the lubricity is improved. alleviate the impact during cutting by chipping resistance of the resulting _{(Ti 1-x Al x)} (C y N 1-y) layer, chipping resistance is improved. On the other hand, if the average content ratio y of the C component departs from the range of 0 ≦ y ≦ 0.005, the toughness of the (Ti _1-x Al _x ) (C _y N _1-y ) layer is reduced, so chipping resistance, It is not preferable because the fracture resistance is lowered. Therefore, the average content ratio y of C was determined as 0 ≦ y ≦ 0.005.
Note that the average Al content x of the composite nitride or composite carbonitride layer was measured using an electron beam microanalyzer (Electron-Probe-Micro-Analyzer: EPMA) and the surface was polished. Irradiated from the surface side, it was determined from the average of 10 points of the analysis results of the characteristic X-rays obtained. About the average content rate y of C, it calculated | required by secondary ion mass spectrometry (Secondary-Ion-Mass-Spectroscopy: SIMS). That is, the ion beam was irradiated in a range of 70 μm × 70 μm from the sample surface side, and the concentration in the depth direction was measured for the component emitted by the sputtering action. The average content ratio y of C shows the average value of the depth direction about the composite nitride or composite carbonitride layer of Ti and Al. However, the content ratio of C excludes the inevitable content ratio of C that is included without intentionally using a gas containing C as a gas raw material. Specifically, the content ratio (atomic ratio) of the C component contained in the composite nitride or composite carbonitride layer when the supply amount of Al (CH ₃ ) ₃ is 0 is determined as the inevitable C content ratio. , The inevitable C content is subtracted from the C component content (atomic ratio) contained in the composite nitride or composite carbonitride layer obtained when Al (CH ₃ ) ₃ is intentionally supplied. The value was determined as y.

Ti composite carbonitride layer of _{Al ((Ti 1-x Al} x) (C y N 1-y)) TiAlCN layer crystal structure present invention is a TiAlCN crystal grains having a face-centered cubic structure of NaCl type Configure to include. In the cross section in the direction perpendicular to the tool base of the (Ti _1-x Al _X ) (C _y N _1-y ) layer, the area ratio occupied by the NaCl-type face-centered cubic structure is preferably 70% or more. The reason is that when the area ratio exceeds 70%, particularly excellent chipping resistance and wear resistance are exhibited.
The area ratio of the NaCl-type face-centered cubic structure in the (Ti _1-x Al _x ) (C _y N _1-y ) layer is determined by the composite nitriding of Ti and Al using an electron beam backscattering diffractometer. A hard coating layer made of a material layer is set in a lens barrel of a field emission scanning electron microscope in a state in which a cross section in a direction perpendicular to the tool base is a polished surface, and is 15 kV at an incident angle of 70 degrees on the polished surface. An electron beam with an acceleration voltage is irradiated with an irradiation current of 1 nA to each crystal grain existing within the measurement range of the cross-sectional polished surface, and the length of the composite nitride layer is 50 μm in length in the horizontal direction and normal to the tool base. A crystal having a NaCl-type face-centered cubic structure by measuring an electron beam backscatter diffraction image at an interval of 0.01 μm / step with respect to the hard coating layer below the film thickness and analyzing the crystal structure of each crystal grain. Grain structure and other fine crystals And the identification of the crystal structure, by obtaining the ratio of the number of pixels corresponding to a cubic structure occupying the total number of pixels of these crystal structures were determined area ratio of the cubic crystal structure.

The layer thickness of the hard coating layer at the location of 200 μm from the ridge line portion to the rake face side is within a range of 30% to 95%, and the layer thickness of the hard coating layer at the location of 200 μm from the ridge line portion to the clearance surface side is 30 to 95%. The thickness of the hard coating layer is 30% to 95% at a location of 200 μm from the ridge line portion to the rake face side with respect to the layer thickness of the ridge line portion. On the flank side where the work material flows, by gradually reducing the distance from the ridge line part to the flank side so as to be within the range of 30 to 95% at the 200 μm portion, the interface between the tool and the work material Chipping tends to occur at the time of detachment of the intervening product, but chipping can be suppressed by making the layer thickness thinner than the ridge line part, and on the rake face side where chips generated by cutting flow, By rubbing with chips, Away it is likely to occur, but it is possible to suppress abnormal damage by thinner than the ridge line part of thickness.
Moreover, the suppression of the above-mentioned chipping and the above-described suppression of the damage are within the range of 40% to 90% of the layer thickness of the hard coating layer with respect to the layer thickness of the ridge line portion from the ridge line portion to the rake face side at 200 μm. Further, it is more certain by gradually reducing the ridgeline portion from the ridgeline portion to the flank side so that it is within a range of 40 to 90% at a location of 200 μm.
In addition, as shown in FIG. 1, the ridge line part as used in this invention is the area | region (namely, hard coating layer surface) which connected the point which the said straight line bends, when a rake face and a flank face are each approximated by a straight line. In the region from the rake face bending point to the flank bending point), the point on the surface of the hard coating layer that is closest to the intersection of the approximate lines (the point indicated by the dotted line arrow), and the rake line to the rake face The distance to the side and the flank side is the distance from the intersection.

  In order to improve wear resistance, an Al oxide layer or nitride layer, or a Ti nitride layer, carbide layer, carbonitride layer, carbonate layer and carbonitride layer may be formed on the hard coating layer. One or two or more of the oxide layers may be formed with a total layer thickness of 1 to 25 μm.

  Furthermore, as the bonding layer, one or more Ti layers of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer between the tool base and the hard coating layer are used. A lower layer made of a compound layer and having a total average layer thickness of 0.1 to 20 μm may be formed.

The production method of the present invention is roughly as follows.
1. A cemented carbide substrate is manufactured by a normal manufacturing method.
2. Next, a binder phase is formed on the cemented carbide substrate as necessary.
3. Subsequently, film formation is performed by a normal CVD apparatus to form a hard coating layer.
For example, reaction gas composition (volume%)
Gas group A: NH ₃ : 0.8 to 1.6%, H ₂ : 45 to 55%
Gas group B: AlCl ₃ : 0.5 to 0.7%, TiCl ₄ : 0.1 to 0.3%,
_{N 2: 0.0~10.0%, C 2} H 4: 0.0~0.2%, H 2: remainder feed period: 1-5 seconds,
Gas supply time per cycle: 0.15 to 0.25 seconds,
Phase difference between gas supply A and gas supply B: 0.10 to 0.20 seconds Reaction atmosphere temperature: 700 to 900 ° C.
Reaction atmosphere pressure: 4-5 kPa,
By depositing under the above conditions, a hard coating layer satisfying 0.70 ≦ x ≦ 0.95 and 0 ≦ y ≦ 0.005 (where x and y are atomic ratios) can be formed. it can.
4). Adjustment of the layer thickness of the hard coating layer Various methods can be used to adjust the layer thickness of the hard coating layer to 200-μm from the ridge line part to the rake face side and 200 μm from the flank side to 30-95% of the layer thickness of the ridge line part. For example, a method by wet blasting using Al ₂ O ₃ is desirable.

Next, the coated tool of the present invention will be specifically described with reference to examples. In addition, as an Example, although the coated tool which uses a WC base cemented carbide as a tool base | substrate is described, it is the same also when using a TiCN base cermet and a cBN base super high pressure sintered compact as a tool base | substrate.

As raw material powders, WC powder, TaC powder, Cr ₃ C ₂ powder and Co powder all having an average particle diameter of 1 to ₃ μm are prepared, and these raw material powders are blended into the blending composition shown in Table 1, After adding wax and ball-milling in acetone for 24 hours, drying under reduced pressure, it was press-molded into a green compact of a predetermined shape at a pressure of 98 MPa, and this green compact was within a range of 1370 to 1470 ° C. in a vacuum of 5 Pa. The tool substrate α made of WC-base cemented carbide having an insert shape of ISO standard SEEN1203AFSN was manufactured after sintering under vacuum at a predetermined temperature of 1 hour under the condition of holding for 1 hour.

Next, a normal CVD apparatus is used on the surfaces of these tool bases α. First, (Ti _1-x Al _x ) (C _y N _1-1 ) having a predetermined composition under the conditions shown in Tables 2 and 3. _y ) A layer is formed by vapor deposition until the target layer thickness is reached, and then (Ti _1-x Al _x ) (C _y on the rake face side and flank face side from the ridge line portion by wet blasting using Al ₂ O _3. The layer thickness of the N _1-y ) layer was adjusted, and the present coated tools 1 to 12 shown in Table 5 were produced. In addition, about this invention coated tools 10-12, on the conditions described in Table 4, the lower layer and / or the upper layer are provided.

Further, for the purpose of comparison, a conventional CVD apparatus was similarly used on the surface of the tool base α, and under the conditions shown in Tables 2 and 3, (Ti _1-x Al _x ) (C _y N _1-y of the comparative example). The comparative coating tools 1-12 shown in Table 6 were manufactured by vapor-depositing layers with the target layer thickness. In addition, about the comparison coating tools 10-12, on the conditions described in Table 4, the lower layer and / or the upper layer are provided.

Moreover, the cross section of the coating layer of this invention coating tool 1-12 and comparative example coating tool 1-12 is measured using a scanning electron microscope, and the location of 200 μm from the ridge line part and the ridge line part to the rake face side and the flank face side The layer thicknesses were measured and listed in Tables 5 and 6. Moreover, about this invention coated tool 1-12, it confirmed that the layer thickness from the ridgeline part to the rake face side and the flank face side to the 200 micrometers location was decreasing gradually.

   Tables 5 and 6 show the results of the average Al content ratio x and the average C content ratio y of the hard coating layer.

Next, in the state where each of the above various coated tools is clamped to a tool steel cutter tip portion with a cutter diameter of 125 mm by a fixing jig, the present invention coated tools 1 to 12 and comparative example coated tools 1 to 12, The following three types of dry high-speed face milling, which is a kind of high-speed high-feed cutting of alloy steel, and a center-cut cutting test were performed, and the flank wear width of the cutting edge was measured.
<Cutting test 1>
Work material: Block material of JIS / SCM440 width 100mm, length 400mm
Rotational speed: 892 min ⁻¹
Cutting speed: 350 m / min,
Cutting depth: 2.0 mm,
Single blade feed rate: 0.2 mm / tooth,
Cutting time: 8 minutes <Cutting test 2>
Work material: Block material of JIS / S55C width 100mm, length 400mm
Rotational speed: 968 min ⁻¹
Cutting speed: 380 m / min,
Cutting depth: 2.0 mm,
Single blade feed rate: 0.2 mm / tooth,
Cutting time: 8 minutes <Cutting test 3>
Work material: Block material of JIS / FCD700 width 100mm, length 400mm
Rotational speed: 892 min ⁻¹
Cutting speed: 350 m / min,
Cutting depth: 2.0 mm,
Single blade feed rate: 0.2 mm / tooth,
Cutting time: 8 minutes Table 7 shows the results of the cutting tests.

From the results shown in Tables 5 to 7, the coated tools 1 to 12 of the present invention have a layer thickness of the hard coating layer at 200 μm from the ridge line portion to the rake face side with respect to the layer thickness of the hard coating layer in the ridge line portion. Since the thickness of the hard coating layer in the range of 30 to 95% is in the range of 30 to 95% from the ridgeline portion to the flank side within the range of 30% to 95%, the layer thickness is sequentially changed. Excellent chipping resistance and wear resistance in feed processing.
On the other hand, for the comparative coated tools 1 to 12 that do not satisfy the invention-specific matters of the present invention, not only abnormal damage such as chipping, chipping or peeling occurs in the hard coating layer, but also for a relatively short time. It is clear that the service life is reached.

As described above, the coated tool of the present invention can be used as a coated tool for various work materials as well as high-speed high-feed cutting of alloy steel, and has excellent chipping resistance over a long period of use. Since it exhibits wear resistance, it can satisfactorily meet the demands for higher performance of cutting devices, labor saving and energy saving of cutting, and cost reduction.

Claims (5)

In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base composed of either a WC cemented carbide, a TiCN-based cermet, or a cBN-based ultrahigh-pressure sintered body,
(A) The hard coating layer includes at least a composite nitride or composite carbonitride layer of Ti and Al having a ridge line thickness of 1 to 20 μm, and has a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the average content x of Ti in the total amount of Ti and Al in the composite nitride or composite carbonitride layer, and the average content of C in the total amount of C and N ( However, x and y are both atomic ratios) satisfy 0.60 ≦ x ≦ 0.95 and 0 ≦ y ≦ 0.005, respectively.
(B) The hard coating layer includes a columnar structure and includes at least a phase of a composite nitride or composite carbonitride of Ti and Al having a NaCl-type face-centered cubic structure,
(C) The hard coating layer has a layer thickness in the range of 30% to 95% from the ridge line part to the rake face side to the rake line part from the ridge line part to the flank side and 200 μm from the ridge line part to the flank side. A surface-coated cutting tool characterized in that the film thickness is gradually reduced so that the layer thickness in each of the points is within a range of 30% to 95%. The layer thickness at the 200 μm portion from the ridge line portion to the rake face side is in the range of 40% to 90% with respect to the layer thickness of the ridge line portion, and the layer thickness at the 200 μm portion from the ridge line portion to the relief surface side is 40%. The surface-coated cutting tool according to claim 1, which is in a range of ˜90%. In the cross section of the composite nitride layer in the direction perpendicular to the tool substrate, the area ratio occupied by the composite nitride or composite carbonitride of Ti and Al having a NaCl-type face-centered cubic structure is 70% or more. The surface-coated cutting tool according to claim 1 or 2, characterized in that One of an oxide layer or a nitride layer of Al or at least one of a nitride layer, a carbide layer, a carbonitride layer, a carbonate layer, and a carbonitride layer of Ti on the hard coating layer The surface-coated cutting tool according to any one of claims 1 to 3, wherein the layer or two or more layers are formed with a total layer thickness of 1 to 25 µm. Between the tool base and the hard coating layer, consisting of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer of one or two or more Ti compound layers, The surface-coated cutting tool according to any one of claims 1 to 4, wherein a lower layer having a total average layer thickness of 0.1 to 20 µm is present.