JP7471440B2 - Coated tool and cutting tool equipped with same - Google Patents

Description

The present disclosure relates to a coated tool used in cutting processing and a cutting tool equipped with the same.

Currently, cermets whose main component is titanium (Ti) are widely used as the base material for cutting tools, wear-resistant components, sliding components, and other components that require wear resistance, sliding properties, and chipping resistance.

For example, Patent Document 1 describes a cutting insert made of a surface-coated titanium carbonitride-based cermet having a through hole for attachment to a tool body. Patent Document 1 also describes providing a metal stain layer on the inner surface of the attachment through hole in order to provide an insert that is less susceptible to abnormal damage even during high-load cutting.

JP 2012-245581 A

The coated tool of the present disclosure is a coated tool comprising a substrate which is a cermet containing hard particles and a binder phase, and a coating layer located on the substrate. The coated tool has a first surface, a second surface, a cutting edge located on at least a part of the ridge of the first surface and the second surface, a third surface located opposite the first surface, and a through hole extending from the first surface to the third surface. The inner wall constituting the through hole has a binder phase-rich layer at least in the center, which has a higher binder phase content than the inside of the substrate. The thickness T1 of the binder phase-rich layer in the center is thicker than the thickness T2 of the binder phase-rich layer at the end of the inner wall. The coating layer is located at least on the binder phase-rich layer. The coating layer has a first layer containing cubic titanium carbonitride. The first layer has an orientation coefficient Tc(220) of titanium carbonitride of 3.0 or more by X-ray diffraction analysis.

FIG. 1 is a perspective view showing an example of a coated tool according to the present disclosure. FIG. 2 is a schematic diagram in cross section showing an example of a coated tool of the present disclosure. FIG. 3 is an enlarged schematic cross-sectional view of a coated tool of the present disclosure. FIG. 4 is an enlarged schematic cross-sectional view of another embodiment of a coated tool of the present disclosure. FIG. 5 is an enlarged schematic cross-sectional view of another embodiment of a coated tool of the present disclosure. FIG. 6 is a schematic enlarged view of a coating layer of the coated tool of the present disclosure. FIG. 7 is a plan view showing an example of a cutting tool according to the present disclosure. FIG. 8 is an enlarged schematic view of a cross section of a coated cutting tool according to the present disclosure.

<Coated tools>
The coated tool of the present disclosure will be described in detail below with reference to the drawings. However, for the sake of convenience, each of the drawings referred to below shows only the main components necessary for explaining the embodiment in a simplified manner. Therefore, the coated tool of the present disclosure may include any component not shown in each of the drawings referred to. Furthermore, the dimensions of the components in each drawing do not faithfully represent the dimensions of the actual components and the dimensional ratios of each component. These points are also true for the cutting tool described below.

It is desirable for coated tools used in cutting processes to have little abnormal damage. The present disclosure provides a coated tool with little abnormal damage and a cutting tool equipped with the same.

The coated tool of the present disclosure has a substrate that is a cermet containing hard particles and a binder phase. The hard particles are, for example, TiCN, TiC, TiN, or (TiM)CN (wherein M is one or more selected from W, Nb, Ta, Mo, and V). The binder phase is mainly composed of an iron group metal such as Ni or Co. The main component is one that occupies 50% or more by mass of the constituent components.

As shown in Figures 1 and 2, the shape of the coated tool 1 of the present disclosure may be, for example, a rectangular plate shape. The first surface 5, which is the top surface in Figure 1, is a so-called rake surface. The coated tool 1 also has a second surface 7, which is a side surface connected to the first surface 5.

The coated tool 1 has a third surface 9, which is the underside opposite to the first surface 5. The second surface 7 is connected to each of the first surface 5 and the third surface 9.

The coated tool 1 of the present disclosure has a cutting edge 11 located at least in a part of the ridge where the first surface 5 and the second surface 7 intersect. In other words, the coated tool 1 of the present disclosure has a cutting edge 11 located at least in a part of the ridge where the rake face and the flank face intersect. The cutting edge 11 has a fourth surface that is continuous with the first surface 5 and the second surface 7. The fourth surface may be a C surface (chamfered surface) in which the corner between the first surface 5 and the second surface 7 is cut obliquely and linearly. The fourth surface may also be an R surface (rounded surface) in which the corner between the first surface 5 and the second surface 7 is rounded.

In the coated tool 1, the entire outer periphery of the first surface 5 may be a cutting edge 11, but the coated tool 1 is not limited to this configuration and may, for example, have a cutting edge 11 on only one side of a rectangular cutting face, in other words, on one of the four fourth surfaces.

The coated tool 1 of the present disclosure has a through hole 15 penetrating the substrate 3 from the first surface 5 to the third surface 9. As shown in FIG. 3, a binder-enriched layer 19 is present at least in the central portion 17a of the inner wall 17 constituting the through hole 15. The binder-enriched layer 19 contains hard particles and a binder phase, and is a region having a higher binder phase content than the inside of the substrate 3. The inside of the substrate 3 means a portion 500 μm or more away from the surface of the substrate 3. The binder-enriched layer 19 does not need to be present on the entire inner wall 17 of the through hole 15, but it is sufficient that it is located at least in the central portion 17a.

The central portion 17a is the middle portion when the through hole 15 is divided into nine equal parts in the depth direction. The end portion 17b is the end portion when the through hole 15 is divided into nine equal parts in the depth direction.

3, in the coated tool 1 of the present disclosure, the thickness T1 of the binder-enriched layer 19 in the central portion 17a of the inner wall 17 constituting the through hole 15 is thicker than the thickness T2 of the binder-enriched layer 19 in the end portion 17b of the inner wall 17 constituting the through hole 15. The thickness T1 of the binder-enriched layer 19 in the central portion 17a and the thickness T2 of the binder-enriched layer 19 in the end portion 17b are each an average value. The thicknesses T1 and T2 may be measured by observing the cross section of the coated tool 1 using a metallurgical microscope or an electron microscope. The binder-enriched layer 19 may not be present in the end portion 17b.

The coated tool 1 of the present disclosure has such a configuration, which prevents abnormal damage to the coated tool 1 originating from the inner wall 17 to which a large force is applied when the coated tool 1 is fixed to the holder (not shown).

Figure 6 is a schematic enlarged view of the coating layer of the coated tool 1 of the present disclosure. As shown in Figure 6, the coated tool 1 has a coating layer 30.

The coating layer 30 is located at least on the binder phase-enriched layer 19. The coating layer 30 may be located on the first surface 5, or on a surface of the substrate 3 other than the first surface 5. The coating layer 30 improves the properties of the coated tool 1 in cutting, such as wear resistance and chipping resistance.

The coating layer 30 has a first layer 31 and a second layer 32. The first layer 31 is located on the first surface 5 and contains cubic titanium carbonitride. The second layer 32 is located on and in contact with the first layer 31. The second layer 32 may contain, for example, aluminum oxide (Al ₂ O ₃ ).

A titanium nitride layer 33 may be provided between the first layer 31 and the substrate 3. With such a configuration, the bonding between the substrate 3 and the first layer 31 is high.

The first layer 31 has a titanium carbonitride layer 34. In addition to titanium carbonitride, the first layer 31 may contain, for example, titanium carbide, nitride, oxide, carbonate, and carbonitride. Furthermore, as long as the first layer 31 contains cubic titanium carbonitride, it may be a single layer or a laminate of multiple layers.

The main components of the titanium nitride layer 33 and the titanium carbonitride layer 34 are titanium nitride and titanium carbonitride, respectively. "Main component" means the component with the largest mass percentage value compared to other components. The titanium nitride layer 33 and the titanium carbonitride layer 34 may contain components other than titanium nitride and titanium carbonitride, respectively.

The coating layer 30 may be composed of only the first layer 31 and the second layer 32, or may have layers other than these layers. For example, another layer may be present between the substrate 3 and the first layer 31, or another layer may be present on the second layer 32.

The first layer 31 is located at least on the binder-enriched layer 19. The first layer 31 has a portion that is harder than the binder-enriched layer 19. With this configuration, the wear resistance of the clamping portion is increased. The first layer 31 may be formed by a CVD method or a PVD method.

The first layer 31 has a maximum peak on the (220) plane of the cubic titanium carbonitride crystal planes by X-ray diffraction (XRD). The orientation coefficient Tc (220) of titanium carbonitride by X-ray diffraction analysis is 3.0 or more. With such a configuration, the adhesive force between the binder phase-enriched layer 19 and the first layer 31 is strengthened, and peeling from the interface between the binder phase-enriched layer 19 and the first layer 31 is less likely to occur, thereby suppressing abnormal damage to the coated tool 1 caused by peeling. In addition, when another layer is located between the first layer 31 and the binder phase-enriched layer 19, the adhesive force between the other layer and the first layer 31 is strengthened, and peeling from the interface between the other layer and the first layer 31 is less likely to occur, thereby suppressing abnormal damage to the coated tool 1 caused by peeling.

The orientation coefficient Tc(hkl) is calculated by the following formula.
Tc(hkl) = {I(hkl) / _I0 (hkl)} / [(1/7) x Σ{I(HKL) / _I0 (HKL)}]

Here, (HKL) refers to all of the crystal planes (111), (200), (220), (311), (331), (420), and (422). Also, (hkl) refers to each of the crystal planes.

I(HKL) and I(hkl) are the peak intensities of the peaks assigned to each crystal plane detected in the X-ray diffraction analysis of the cubic titanium carbonitride of the first layer 31.

I ₀ (HKL) and I ₀ (hkl) are the standard diffraction intensities of each crystal plane described in JCPDS Card No. 00-042-1489.

The above orientation coefficient Tc(hkl) may be measured from the flat upper surface of the first layer 31, for example, from the second surface 7.

Examples of the second layer 32 containing aluminum oxide include α-alumina (α-Al ₂ O ₃ ), γ-alumina (γ-Al ₂ O ₃ ), and κ-alumina (κ-Al ₂ O ₃ ). When the second layer 32 contains α-alumina, the heat resistance of the coated tool 1 can be improved. The second layer 32 may contain only one of the above compounds, or may contain a plurality of the above compounds.

Whether the aluminum oxide contained in the second layer 32 is one of the above compounds can be evaluated, for example, by performing X-ray diffraction (XRD) analysis and observing the distribution of peak values.

The first layer 31 may contain a component other than titanium carbonitride. The second layer 32 may contain a component other than aluminum oxide. For example, the first layer 31 may contain aluminum oxide. The second layer 32 may contain a titanium compound such as titanium carbonitride. In such a case, the bonding strength between the first layer 31 and the second layer 32 is improved.

The binder-enriched layer 19 has a lower hardness than the substrate 3 and a higher hardness than the metal stain layer as described in Reference 1. Therefore, the binder-enriched layer 19 is more inhibited from deforming than the metal stain layer.

Due to the above-mentioned configuration, when the coated tool 1 is fixed to the holder by the clamp, the local force acting on the substrate 3 is small due to the suppressed deformation of the binder phase-enriched layer 19 in the central portion 17a of the inner wall 17 at the time of contact between the central portion 17a and the clamp, and therefore the coated tool 1 is less likely to crack or be abnormally damaged.

The size of the coated tool 1 is not particularly limited, but for example, the length of one side of the cutting face is set to about 3 to 20 mm. The thickness of the coated tool 1 is set to about 1 to 20 mm, for example. In addition, while a rectangular coated tool 1 is illustrated in FIG. 1, it may be, for example, triangular or disc-shaped.

As shown in FIG. 4, the coated tool 1 of the present disclosure may have an expanded diameter portion 21 connected to the inner wall 17. There is a step at the boundary between the through hole 15 and the expanded diameter portion 21. In the example shown in FIG. 4, the binder-enriched layer 19 is not present on the inner wall of the expanded diameter portion 21, but the binder-enriched layer 19 may also be present in the expanded diameter portion 21. In the coated tool 1 of the present disclosure, the expanded diameter portion 21 is not included in the through hole 15. The expanded diameter portion 21 is a so-called countersunk surface. The diameter of the expanded diameter portion 21 is larger than the diameter of the through hole 15 by 300 μm or more.

The thickness T1 of the binder-enriched layer 19 in the central portion 17a may be 1 μm or more. Also, the thickness T1 may be 20 μm or less. With such a configuration, abnormal damage to the coated tool 1 is suppressed. The thickness T1 may be 3 μm or more. Also, the thickness T1 may be 10 μm or less.

The thickness T2 of the binder-enriched layer 19 at the end 17b may be 0.2 μm or more. The thickness T2 may be 6 μm or less. With this configuration, abnormal damage to the coated tool 1 is suppressed.

As shown in Figure 5, the diameter R1 at the center portion 17a may be larger than the diameter R2 at the end portion 17b. With this configuration, the contact area between the clamp and the inner wall 17 is increased, and the clamping force is increased.

The diameter R1 at the center portion 17a may be 5 μm or more and 30 μm or less larger than the diameter R2 at the end portion 17b. With this configuration, abnormal damage to the coated tool 1 is suppressed.

The hardness of the binder-enriched layer 19 in the central portion 17a may be 10 GPa or more and 20 GPa or less. With this configuration, when the clamp pin contacts, the binder-enriched layer 19 is appropriately deformed, and the clamping force is increased. The hardness of the binder-enriched layer 19 in the central portion 17a may be measured by using a nanoindentation method to measure the exposed binder-enriched layer 19 in the cross section of the coated tool 1.

The binder-enriched layer 19 in the central portion 17a may have a metal layer (not shown) on the through-axis side of the through-hole 15 that has a higher binder phase content than the binder-enriched layer 19. This metal layer does not include a hard layer and is composed only of metal. With such a configuration, the metal layer functions as a buffer between the clamp described below and the binder-enriched layer 19, thereby suppressing abnormal damage to the coated tool 1. The thickness of the metal layer may be 0.3 μm or more and 2 μm or less.

<Method of manufacturing coated tools>
The method for producing the coated tool of the present disclosure will be described below.

The raw material powders used in the manufacture of the coated tools of the present disclosure are those typically used in the manufacture of cermets.

The substrate may contain, for example, 40% by mass or more and 80% by mass or less of TiCN as hard particles and 6% by mass or more and 30% by mass or less of Co as a binder phase. In order to further improve the characteristics, the substrate may contain WC, TaC, NbC, _Mo2C , VC, ZrC, etc.

The raw material having the above-mentioned composition is formed into a shape having a space that will become a through hole after firing. Then, for example, the raw material is fired at a temperature of 1400° C. or more and 1600° C. or less. The firing atmosphere may be a _N2 partial pressure atmosphere.

When the _N2 partial pressure is 1 kPa or more, the thickness of the binder-phase-rich layer after firing becomes thick. Also, when the average particle diameter d50 of the hard particles used as the raw material is 0.7 μm or less, a binder-phase-rich layer having a metal layer with a higher binder phase content than the binder-phase-rich layer is obtained on the through-hole axis (not shown) side.

In addition, if the molding pressure is high during the above molding, deformation during firing can be suppressed. On the other hand, if the molding pressure is low during molding, the diameter R1 at the center of the inner wall tends to become larger than the diameter R2 at the end. The relationship between molding pressure and deformation varies depending on the composition and firing temperature, so it is recommended to adjust it in various combinations.

For example, after firing, a rotating brush is inserted into the through hole from both ends to polish the inner wall of the through hole, so that the thickness T1 of the binder-enriched layer in the center is thicker than the thickness T2 of the binder-enriched layer at the ends. The brush may be inserted from both sides of the through hole, or may be inserted twice from one side.

Next, a coating layer is formed on the surface of the substrate by chemical vapor deposition (CVD). First, a titanium carbonitride layer in the first layer is formed on the surface of the substrate. A first mixed gas is prepared by mixing hydrogen gas with 0.5% to 10% by volume of titanium tetrachloride gas, 1% to 60% by volume of nitrogen gas, and 0.1% to 3.0% by volume of acetonitrile gas. While introducing this first mixed gas into the chamber, the acetonitrile gas is increased by 0.4% by volume per hour from the start of film formation. At this time, the first mixed gas is introduced into the chamber at a gas partial pressure of 6 kPa to 12 kPa, and a titanium carbonitride layer containing MT-titanium carbonitride is formed in a temperature range of 830°C to 870°C.

Next, the second layer 32 is formed. The film formation temperature is set to 950°C or more and 1100°C or less, the gas pressure is set to 5 kPa or more and 20 kPa or less, and the composition of the reaction gas is prepared by mixing hydrogen gas with 5 vol% or more and 15 vol% or less of aluminum trichloride (AlCl ₃ ) gas, 0.5 vol% or more and 2.5 vol% or less of hydrogen chloride (HCl) gas, 0.5 vol% or more and 5.0 vol% or less of carbon dioxide gas, and 0 vol% or more and 1 vol% or less of hydrogen sulfide (H ₂ S) gas to prepare a second mixed gas. The second mixed gas is introduced into the chamber, and the second layer 32 is formed. In this way, the coated tool 1 of the present disclosure can be obtained.

After firing, a binder-enriched layer may be present in areas other than the through holes, such as the first, second and third surfaces, but this layer may be removed if necessary.

<Cutting tools>
Next, the cutting tool of the present disclosure will be described with reference to the drawings.

The cutting tool 101 of the present disclosure is, for example, a rod-shaped body extending from a first end (upper end in FIG. 7) to a second end (lower end in FIG. 7) as shown in FIG. 7. The cutting tool 101 includes a holder 105 having a pocket 103 on the first end side (tip side) and the coated tool 1 located in the pocket 103 as shown in FIG.

As shown in FIG. 8, the clamp 107 is inserted into the through hole 15 (see FIG. 1) of the coated tool 1. In the example shown in FIG. 8, the clamp 107 is in direct or indirect contact with the binder-enriched layer 19 (see FIG. 2) located in the central portion 17a. Indirect contact between the clamp 107 and the binder-enriched layer 19 means a state in which a metal layer or a coating layer exists between the binder-enriched layer 19 and the clamp 107. The binder-enriched layer 19 with which the clamp 107 is in contact is more easily deformed than the substrate 3, so that a strong local force is not likely to be applied to the coated tool 1. In addition, when the coated tool 1 has the binder-enriched layer 19, the contact area between the clamp 107 and the binder-enriched layer 19 is large, so that the coated tool 1 is less likely to move in the pocket during cutting. Due to these effects, the coated tool 1 of the present disclosure is less likely to be abnormally damaged. The cutting tool 101 is provided with the coated tool 1, so that stable cutting can be performed for a long period of time.

The pocket 103 is a portion in which the coated tool 1 is attached, and has a seating surface parallel to the underside of the holder 105 and a restraining side surface inclined relative to the seating surface. The pocket 103 is also open on the first end side of the holder 105.

The coated tool 1 is located in the pocket 103. At this time, the underside of the coated tool 1 may be in direct contact with the pocket 103, or a sheet (not shown) may be sandwiched between the coated tool 1 and the pocket 103.

The coated tool 1 is attached to the holder 105 so that at least a part of the portion used as the cutting edge 11 at the ridge where the rake face and the flank face intersect protrudes outward from the holder 105. In this embodiment, the coated tool 1 is attached to the holder 105 by a clamp 107. That is, the coated tool 1 is attached to the holder 105 by inserting the clamp 107 into the through hole 15 of the coated tool 1 and inserting the tip of the clamp 107 into a screw hole (not shown) formed in the pocket 103 to screw the threaded portions together.

The holder 105 may be made of steel, cast iron, or the like. Of these materials, steel may be used, which has high toughness.

In this embodiment, a cutting tool 101 used for so-called turning is exemplified. Examples of turning include internal diameter machining, external diameter machining, groove machining, and end face machining. The cutting tool 101 is not limited to those used for turning. For example, the coated tool 1 of the above embodiment may be used for the cutting tool 101 used for turning.

The coated tools of the present disclosure are described below.

The substrate was prepared as follows. After adding a binder to the raw powder containing 40% by mass of TiCN, 12% by mass of TiN, 20% by mass of WC, 8% by mass of NbC, 20% by mass of Co, and other unavoidable carbides, the raw powder was pressed into the desired shape to produce a molded body in the shape of a tool having a through hole. These raw powders are generally used in the manufacture of cermets. The composition of the substrate disclosed herein is also not special. After removing the binder component, the substrate was fired in a nitrogen atmosphere of 3 kPa at a temperature of 1530°C for 1 hour to obtain a substrate having a binder-phase-enriched layer with a metal layer on the inner wall of the through hole. After that, a coating layer was formed on the substrate based on the above-mentioned coating layer formation process.

Thereafter, the inner wall of the through hole was polished with a brush to prepare a coated tool having the configuration shown in Table 1. Note that in the areas where no binder-enriched layer was present or where the binder-enriched layer was thin, the time of polishing with the brush was extended.

In addition, the first, second, and third surfaces of all coated tools were blasted to remove the binder-enriched layer.

Polishing with a brush was performed by applying an abrasive liquid made of 0.1 to 3 μm diamond powder and lubricating oil to a boar hair brush, and then inserting the boar hair brush into the through hole while rotating it.

The thickness at the center and ends of the binder phase-enriched layer, the diameter R1 at the center, and R2 at the ends were measured on a cross section obtained by cutting the substrate in the thickness direction at a plane including the through axis.

In addition, when the hardness inside the substrate and the hardness of the binder-enriched layer were measured using a cross-section of the coated tool, the hardness of the binder-enriched layer was found to be lower than the hardness inside the substrate.

The obtained coated tool was placed in the pocket of the holder, and a clamp was inserted into the through hole of the coated tool to fix the coated tool. Then, a cutting test was performed under the following conditions.

<Failure resistance test>
Work material: SCM435 with 4 grooves (5mm width) Cutting speed: 300m/min
Feed: 0.3 mm/rev
Cutting depth: 0.5 mm
Cutting condition: Wet evaluation method: The presence or absence of chipping or damage after applying impact 10,000 times was judged.

In addition, the first layer of all samples in Table 1 had a titanium carbonitride orientation coefficient Tc(220) of 3.5 as determined by X-ray diffraction analysis. Samples No. 1, 2, and 9, which do not have the configuration of the coated tool of the present disclosure, experienced abnormal damage. The coated tool of the present disclosure suppressed abnormal damage. In addition, the coated tool was well held in the holder, and the surface roughness of the machined workpiece was also good.

The coated tool and cutting tool equipped therewith of the present disclosure described above are merely examples, and may have different configurations without departing from the gist of the present application.

REFERENCE SIGNS LIST 1: Coated tool 3: Base 5: First surface 7: Second surface 9: Third surface 11: Cutting edge 15: Through hole 17: Inner wall 17a: Center portion 17b: End portion 19: Binder-enriched layer 21: Enlarged diameter portion T1: Thickness of binder-enriched layer at center portion T2: Thickness of binder-enriched layer at end portion R1: Diameter at center portion R2: Diameter at end portion 101: Cutting tool 103: Pocket 105: Holder 107: Clamp

Claims (9)

1. A coated tool comprising a substrate, the substrate being a cermet containing hard particles and a binder phase, and a coating layer disposed on the substrate, the coating layer comprising:
The coated tool comprises:
The first page and
The second side,
A cutting edge located at least part of a ridge line of the first surface and the second surface;
a third surface located opposite the first surface, and a through hole extending from the first surface to the third surface,
an inner wall constituting the through hole has, at least in a central portion, a binder-phase-enriched layer having a higher content of the binder phase than the inside of the base;
a thickness T1 of the binder-phase-rich layer at the central portion is greater than a thickness T2 of the binder-phase-rich layer at the end portion of the inner wall;
the coating layer is located on at least the binder phase enriched layer;
The coating layer has a first layer containing cubic titanium carbonitride,
the first layer has an orientation coefficient Tc(220) of the titanium carbonitride of 3.0 or more as determined by X-ray diffraction analysis. A coated tool as described in claim 1, wherein the thickness T1 is 1 μm or more and 20 μm or less. A coated tool as described in claim 1 or 2, wherein the thickness T2 is 0.2 μm or more and 6 μm or less. A coated tool according to any one of claims 1 to 3, wherein the diameter R1 at the central portion is greater than the diameter R2 at the end portion. The coated tool of claim 4, wherein the diameter R1 is greater than the diameter R2 by 5 μm or more and 30 μm or less. A coated tool according to any one of claims 1 to 5, wherein the hardness of the binder phase-enriched layer in the central portion is 10 GPa or more and 20 GPa or less. A coated tool according to any one of claims 1 to 6, wherein the binder-enriched layer in the central portion has a metal layer on the through-axis side of the through hole that has a higher binder phase content than the binder-enriched layer. A coated tool according to any one of claims 1 to 7, wherein the coating layer has a portion having a higher hardness than the binder phase-enriched layer. a holder having a length extending from a first end to a second end and having a pocket located on the first end side;
The coated tool according to any one of claims 1 to 8, which is located in the pocket;
a clamp inserted into the through hole of the coated tool.

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