WO2022210760A1 - Drilling tip and drilling tool - Google Patents

Abstract

A drilling tip according to the present invention comprises: a tip body (2) having a rear end part (2A) that forms a columnar shape or a disk shape around the center line (C) of the tip, and a head part (2B); and a hard layer (3) covering the head part (2B). The hard layer (3) has an outermost layer (4) comprising a cBN sintered body having cubic boron nitride particles and a binder phase. The binder phase contains Ti₂CN and TiAl₃.

Description

drilling tips and drilling tools

The present invention relates to drilling tips and drilling tools.
This application claims priority based on Japanese Patent Application No. 2021-061362 filed in Japan on March 31, 2021, the content of which is incorporated herein.

As a drilling tip that is attached to the tip of a drilling tool for drilling, in order to extend the life of the impact drilling bit, the tip body of the tip body made of cemented carbide has polycrystals harder than the tip body at the tip of the base body. Drilling tips coated with a hard layer of sintered diamond are known. For example, in Patent Document 1, such a polycrystalline A drilling tip coated with multiple hard layers of sintered diamond has been proposed.

Also, as a drilling tip, a drilling tip joined to the tip of a pick attached to the outer periphery of a rotating drum of a drum-type drilling rig used for open-pit mining or long-wall mining is known. Patent Literature 2 proposes a drilling tip in which a substantially conical tip portion of a tip body is coated with diamond and/or cubic boron nitride. Patent Document 3 discloses that the outermost layer covering the substantially conical tip of the tip body is selected from polycrystalline diamond, polycrystalline cubic boron nitride, single-crystalline diamond, and cubic boron nitride composites. Proposed.

Regarding cubic boron nitride sintered bodies, Patent Document 4 discloses a cubic boron nitride sintered body with a binder phase containing Al ₂ O, AlB ₂ , AlN, TiB ₂ and TiN to improve strength and toughness. A cutting tool has been proposed which is composed of a joint.

U.S. Pat. No. 4,694,918 (B) U.S. Pat. No. 6,051,079 (B) European Patent Application Publication No. 2053198 (A) Japanese Patent Laid-Open No. 8-197307 (A)

However, although the polycrystalline diamond sintered body has higher wear resistance than cemented carbide, it has poor fracture resistance due to its low toughness. Therefore, chipping or chipping of the hard layer may occur unexpectedly during drilling of the superhard rock layer. In addition, diamond sintered bodies cannot be used in Fe-based or Ni-based mines because of their high affinity. Furthermore, since the heat resistance temperature of the diamond sintered body is also about 700° C., the diamond sintered body cannot be used under the condition of being exposed to a temperature higher than this. For example, under high-temperature excavation conditions of 700° C. or higher, such as open-pit mining performed in a dry environment, diamond is graphitized and wear resistance is lowered.

In addition, cubic boron nitride sintered bodies have a low affinity for Fe-based and Ni-based mines, but are inferior in hardness to diamond. The cubic boron nitride sintered body described in Patent Document 4 has relatively low hardness and insufficient wear resistance and chipping resistance, so it was difficult to apply it to a drilling tool.

Conventionally, when cubic boron nitride sintered bodies are used as excavating tools for rock excavation, resistance to fatigue wear due to repeated impacts (fatigue wear resistance) and resistance to abrasive wear (abrasive wear resistance) have been improved. could not secure enough. Furthermore, resistance to damage factors such as damage due to impact and vibration for breaking rocks is not sufficient.
The term "abrasive wear" as used herein refers to wear caused by minute cutting action caused by hard components entering between the cutting edge of the tool and the rock while the crushed rock surrounds the drilling tool.

A digging tool is a tool for digging through the ground or bedrock. On the other hand, rocks in the ground are not uniform in composition and strength, and are brittle materials. Therefore, unlike cutting tools, which emphasize cutting and chipping performance, drilling tools have the performance to withstand the impact and vibration that destroy rocks, as well as the performance to withstand rotation to efficiently remove the destroyed rocks. is necessary.

In other words, the materials used for drilling tools are required to have fatigue wear resistance, abrasive wear resistance, and resistance to damage factors such as chipping due to impact and vibration to break rocks.

The present invention has been made under such a background, and has excellent fatigue wear resistance and abrasive wear resistance, and is resistant to damage factors such as fracture due to impact and vibration for breaking rocks. It is an object of the present invention to provide a tip and to provide a drilling tool fitted with such a drilling tip.

The present inventors paid attention to cBN sintered bodies as a material for drilling tips and studied them. As a result, when the binder phase in the cBN sintered body contains Ti ₂ CN and TiAl ₃ and the XRD peaks of these Ti ₂ CN and TiAl ₃ have a predetermined relationship, fatigue wear resistance and abrasive wear resistance The inventors have found that the resistance to the above-mentioned damage factors can be improved.
The present invention was made based on this finding, and the gist of the present invention is as follows.

A drilling tip according to one aspect of the present invention is a drilling tip that is configured to be attached to the tip of a drilling bit, and has a cylindrical shape or a disk shape centered (axis) on the center line of the drilling tip. a tip body having a rear end portion and a tip portion whose radius from the center line gradually decreases from the rear end portion toward the tip side of the excavation tip; and a hard layer covering the tip portion of the tip body. and wherein the hard layer has an outermost layer made of a cBN sintered body having cubic boron nitride particles and a binder phase, and the binder phase contains Ti ₂ CN and TiAl ₃ and

In the above drilling tip, in the X-ray diffraction pattern of the outermost layer, the peak intensity I _Ti2CN of Ti CN _appearing at a diffraction angle (2θ) of 41.9 to 42.2° and the diffraction angle (2θ) of I _Ti2CN /I _TiAl3 , which is a ratio of the peak intensity I _TiAl3 of TiAl ₃ appearing at a position of 39.0 to 39.3°, may be 2.0 to 30.0.

In the above drilling tip, the binder phase may contain Al ₂ O ₃ and have an average particle size of 0.9 to 2.5 μm.

In the above drilling tip, in the bonding phase, the TiAl ₃ contains an additive element M1, the additive element M1 is one or more of the group consisting of Si, Mg and Zn, and Auger electron spectroscopy Ratio of the average area S _TiAlM1 of the region where Ti and Al and the additional element M1 overlap to the average area S _TiAl of the region where Ti and Al overlap in the mapping images of Ti, Al, and the additional element M1 according to the method S _TiAlM1 /S _TiAl may be 0.05 to 0.98.

In the drilling tip, the hard layer includes an intermediate layer between the outermost layer and the tip body, and the intermediate layer contains 10.0 to 70.0 vol% of cubic boron nitride particles or diamond particles. may contain.

In the above drilling tip, the volume fraction of the cubic boron nitride particles in the outermost layer may be 70.0 to 95.0 vol%.

In the above drilling tip, the cubic boron nitride particles in the outermost layer may have an average particle diameter of 0.5 to 30.0 μm.

Further, a digging tool of one aspect of the present invention is characterized by comprising the above-described digging tip, and a tool body that holds the digging tip on its distal end surface and is rotated around an axis.

INDUSTRIAL APPLICABILITY According to the present invention, a drilling tip having excellent fatigue wear resistance and abrasive wear resistance and resistance to damage factors such as chipping due to impact and vibration for breaking rocks, and such a drilling tip. An attached drilling tool can be provided.

FIG. 1 is a cross-sectional view taken along the centerline of the tip showing an embodiment of the drilling tip of the present invention. FIG. 2 is a cross-sectional view along the centerline of the tip showing a modification of the drilling tip of the present embodiment. FIG. 3 is a cross-sectional view along the axis of the bit body showing an embodiment of the drilling bit of the present invention, in which the drilling tip of the present embodiment shown in FIG. 1 is attached to the tip of the bit body. FIG. 4 is an X-ray diffraction pattern of Example 3 of the present invention. FIG. 5 is a diagram schematically showing overlapping portions of Ti element and Al element based on elemental mapping by Auger electron spectroscopy in Example 8 of the present invention. FIG. 6 is a diagram schematically showing overlapping portions of Ti element, Al element and Si element based on elemental mapping by Auger electron spectroscopy in Example 8 of the present invention.

The drilling tip and drilling tool of the present invention will be described in more detail below. In addition, the lower limit value and the upper limit value are included in the numerical limitation range described below between "-". Numerical values indicated as "less than" and "greater than" do not include the value within the numerical range.

FIG. 1 is a cross-sectional view showing an embodiment of the drilling tip of the present invention, and FIG. 2 is a cross-sectional view along the centerline of the tip showing a modification of the drilling tip of the present embodiment. FIG. 3 is a cross-sectional view showing an embodiment of the drilling bit of the present invention to which the drilling tip of the present embodiment is attached.
The shape of the drilling tip of the present invention is cylindrical with one rounded end. The centerline C of the tip is a straight line parallel to the axial direction of the cylindrical shape and passing through the center of the drilling tip. The center of the drilling tip is the center when the drilling tip is viewed from the axial direction (planar view).

The excavation tip 1 of the present embodiment has a rear end portion 2A having a cylindrical shape or a disc shape centered on the center line C of the tip, and a radius from the center line C extending from the rear end portion 2A toward the tip side. It comprises a tip body 2 integrally formed with a tip portion 2B that gradually becomes smaller, and a hard layer 3 covering the surface of the tip portion 2B of the tip body 2. - 特許庁The chip body 2 is made of cemented carbide, for example. Moreover, the hard layer 3 is made of a material having a higher hardness (Vickers hardness) than the tip body 2 . The hard layer 3 may have a single-layer structure consisting of the outermost layer 4 as shown in FIG. It is good also as a multilayer structure provided.

As shown in FIG. 1, the front end portion 2B of the tip body 2 has a convex portion 2a having a convex arc shape with a surface convex toward the tip side in a cross section along the center line C, and a cross section of the convex portion 2a having a surface. and a concave arc-shaped concave portion 2b which is in contact with the convex arc of . Specifically, as shown in FIG. 1, the surface of the concave portion 2b is in contact with the convex arc of the cross section of the convex portion 2a at the point of contact P, and the outer peripheral side of the chip body 2 is gradually increased toward the rear end side of the chip body 2. It is designed to spread over In this embodiment, the surface of the convex portion 2a is formed in a convex spherical shape centered on the center line C, and the surface of the concave portion 2b in the cross section is aligned with the outer peripheral surface of the rear end portion 2A of the tip body 2. intersect at an obtuse angle.

The diameter D (mm) of the rear end portion 2A of the tip body 2 is appropriately selected from the viewpoint of balancing the impact load when used for excavation and the relaxation of the residual stress generated at the interface between the hard layer 3 and the tip body 2. It may be determined and may range, for example, from 8 mm to 20 mm.

The ratio r1/D of the radius r1 (mm) of the convex arc of the convex portion 2a in the cross section along the center line C to the diameter D (mm) of the rear end portion 2A of the tip body 2 is 0.1 to 0.1. It is preferably within the range of 0.65. By setting r1/D within this range, the residual stress at the interface between the hard layer 3 and the chip body 2 can be more reliably alleviated, and the thickness of the hard layer 3 can be sufficiently secured. As a result, it is possible to extend the life of the drilling tool.

Also, the ratio r2/D of the radius r2 (mm) of the concave arc of the recess 2b in the cross section along the center line C to the diameter D (mm) of the rear end portion 2A of the tip body 2 is 0.05. It is preferably within the range of ~3.0. By setting r2/D within this range, similarly, the residual stress in the interface between the hard layer 3 and the chip body 2 can be more reliably relaxed, and the thickness of the hard layer 3 can be sufficiently secured. As a result, it is possible to extend the life of the drilling tool.

Furthermore, in the cross section along the center line C, the angle θ (°) formed by the straight line L connecting the contact point P between the convex portion 2a and the concave portion 2b and the center Q of the convex arc of the convex portion 2a with respect to the center line C may be in the range of 20 (°) to 90 (°). By setting the angle θ within this range, the residual stress on the interface between the hard layer 3 and the chip body 2 can be more reliably alleviated, and a sufficient thickness of the hard layer 3 can be ensured. As a result, it is possible to extend the life of the drilling tool.
In addition, the “cross section along the center line C” as used in this specification may be a cross section along the center line C within a range of 0.1 (mm) from the center line C.

In this embodiment, the tip portion 2B of the tip body 1 is covered with the hard layer 3 . As shown in FIG. 1, the rear end portion 3A of the hard layer 3 continues to the tip side of the rear end portion 2A of the tip body 2. As shown in FIG.
Further, the outer peripheral surface of the rear end portion 3A of the hard layer 3 is a cylindrical surface centered on the center line C and having a diameter D (mm) equal to that of the rear end portion 2A of the tip body 2. As shown in FIG. On the other hand, the surface of the front end portion 3B of the hard layer 3 smoothly continues to the outer peripheral surface of the rear end portion 3A and has a convex hemispherical shape with the center Q as the center. That is, the drilling tip 1 of this embodiment is a so-called button tip.
Further, the thickness of the hard layer 3 may be substantially uniform at least on the tip side of the contact point P. As shown in FIG.

The hard layer 3 of this embodiment has an outermost layer 4 made of a cubic boron nitride sintered body (hereinafter also referred to as a "cBN sintered body"). Here, as described above, the hard layer 3 of this embodiment may have a single-layer structure (FIG. 1) consisting of only the outermost layer 4, or an intermediate layer 5 is provided between the outermost layer 4 and the chip body 2. Such a multilayer structure (FIG. 2) may also be used.
The cBN sintered body constituting the outermost layer 4 has cubic boron nitride grains (hereinafter also referred to as “cBN grains”) and a binder phase that bonds the cBN grains to each other.

Although the average particle size of the cBN particles is not particularly limited, it is preferably in the range of 0.5 to 30.0 μm. By dispersing the hard cBN particles having such a particle size range in the cBN sintered body, the outermost layer 4 can be provided with high fracture resistance.
Specifically, it is possible to suppress the occurrence of chipping originating from unevenness caused by cBN particles falling off the surface of the outermost layer 4 during excavation. In addition, the cBN particles can suppress the propagation of cracks that propagate from the interface between the cBN particles and the binder phase caused by the stress applied to the outermost layer 4 during excavation, or cracks that propagate through the cBN particles. . The average particle size of the cBN particles is more preferably 0.5 to 8.0 μm, more preferably 0.5 to 3.0 μm, but is not limited to this.

The content (vol%) of cBN particles in the cBN sintered body is not particularly limited, but is preferably in the range of 70 to 95vol%. If the content of cBN grains in the cBN sintered body is too low, the cBN grains are in contact with each other and the unsintered portion where the cBN grains are in contact with each other and cannot sufficiently react with the binder phase is reduced. As a result, the hardness of the cBN sintered body of the outermost layer 4 is lowered, and wear resistance and chipping resistance may be deteriorated. On the other hand, if the content of cBN grains is excessively high, voids that act as starting points for cracks are likely to be formed in the sintered body, and chipping resistance may be lowered. Therefore, the content of cBN grains in the cBN sintered body is preferably in the range of 70 to 95 vol %. More preferably 70 to 90 vol%, still more preferably 75 to 85 vol%, but not limited thereto. The content of cBN particles can be adjusted by adjusting the mixing ratio of the cBN particle powder and the raw material powder for forming the binder phase when forming the outermost layer 4 .

Here, the average particle diameter of cBN particles and the content of cBN particles in the cBN sintered body can be obtained as follows.

<Method for measuring average particle size of cBN particles>

Here, the average particle size of cBN particles can be obtained as follows. The cross section of the cBN sintered body is mirror-finished, and the mirror-finished surface is subjected to structural observation with a scanning electron microscope (hereinafter referred to as SEM) to obtain a secondary electron image. Next, the cBN grain portion in the obtained image is extracted by image processing, and the average grain size, which will be described later, is calculated based on the maximum length of each grain determined by image analysis.

Here, in extracting the cBN particle portion in the image by image processing, in order to clearly determine the CBN particle and the bonding phase, the image is displayed in 256-gradation monochrome, with 0 being black and 255 being white. The peak value (v) of the pixel value of the cBN particle portion and the peak value (w) of the pixel value of the bonded phase portion are binarized using the value calculated by (w−v)/2+v as the threshold value. .

In addition, as a region for obtaining the pixel value of the cBN grain portion, for example, a region of about 0.5 μm × 0.5 μm is selected, and the average value obtained from at least three different locations within the same image region is calculated. It is preferable to use the peak value of the pixel values described above. Then, a region of about 0.2 μm×0.2 μm to about 0.5 μm×0.5 μm is selected as a region for obtaining the pixel value of the bonded phase portion, and similarly, from at least three different locations within the same image region. Preferably, the determined average value is taken as the peak value of the aforementioned pixel values of the combined phase.

After the binarization process, a process for separating the portions where the cBN grains are considered to be in contact with each other, such as watershed image processing, is used to separate the cBN grains that are considered to be in contact. do.

　The part (black part) corresponding to the cBN particles in the image obtained after the above-mentioned binarization processing is subjected to particle analysis, and the obtained maximum length of each cBN particle is taken as the diameter of each cBN particle. As a particle analysis for determining the maximum length, the value of the larger length from the two lengths obtained by calculating the Feret diameter for one cBN particle is the maximum length, and that value is the diameter of each cBN particle. .

Assuming that each cBN particle is an ideal sphere having this diameter, the volume obtained by calculation is the volume of each particle, and the cumulative volume is obtained. Based on this cumulative volume, the vertical axis is the volume percentage (%) and the horizontal axis is the diameter. (μm), and the diameter when the volume percentage is 50% is taken as the average particle diameter of the cBN particles. This is performed for three observation areas, and the average value is taken as the average particle size of cBN particles (μm, this average particle size is called D50).

When performing this particle analysis, the length (μm) per pixel is set using the scale value known from the SEM in advance. As the observation area, at least 30 or more cBN particles are observed in the observation area, that is, when the average particle size of the cBN particles is about 3 μm, the observation area is preferably about 15 μm×15 μm, for example.

<Content of cBN particles>
The content of cBN grains in the cBN sintered body can be determined as follows.
First, an arbitrary cross-sectional structure of the cBN sintered body, which is the outermost layer 4, is observed by SEM to obtain a secondary electron image. A portion corresponding to the cBN grains in the obtained secondary electron image is extracted by image processing similar to the method for measuring the average grain size of the cBN grains. Then, the area occupied by the cBN particles is calculated by image analysis, and the ratio occupied by the cBN particles in one image is obtained. The average value of the content of cBN particles obtained by processing at least three images is defined as the content (vol %) of cBN particles in the cBN sintered body. The observation area used for image processing is preferably a square area having a side length five times the average particle size of the cBN particles. For example, when the average particle size of cBN particles is 3 μm, the observation area used for image processing is preferably an area of about 15 μm×15 μm.

In this embodiment, the binder phase in the cBN sintered body contains _Ti2CN and _TiAl3 . Thus, by including Ti ₂ CN and TiAl ₃ in the binder phase, it is possible to improve the adhesion between the cBN grains and the binder phase and improve the toughness of the cBN sintered body. As a result, fatigue wear resistance and abrasive wear resistance can be improved, and resistance to damage factors such as chipping due to impact and vibration during rock excavation can be improved.

In the present embodiment, in the X-ray diffraction pattern of the outermost layer, I _Ti2CN /I _TiAl3 , which is the ratio of the peak intensity I _Ti2CN of Ti ₂ CN to the peak intensity I _TiAl3 of TiAl ₃ , is 2.0 to 30. .0 is preferred. Specifically, in the diffraction pattern obtained by X-ray analysis (XRD) of the outermost layer, the peak intensity I _Ti2CN of _Ti CN that appears at a diffraction angle (2θ) of 41.9 to 42.2°, I _Ti2CN /I _TiAl3 , which is the ratio of the peak intensity I _TiAl3 of TiAl ₃ appearing at a diffraction angle (2θ) of 39.0 to 39.3°, is preferably 2.0 to 30.0.

For Ti ₂ CN and _{TiAl 3} which are components of the _binder phase, fatigue wear resistance, fatigue wear resistance, It has excellent abrasive wear resistance, and can further improve resistance to damage factors such as chipping due to impact and vibration during rock excavation. If I _Ti2CN /I _TiAl3 is less than 2.0, the amount of TiAl ₃ in the cBN sintered body increases excessively, and cBN particles may react with this TiAl ₃ to form coarse TiB ₂ . As a result, coarse TiB ₂ may become a starting point of fracture during excavation of rocks, resulting in damage such as the chipping described above. On the other hand, if I _Ti2CN /I _TiAl3 is greater than 30.0, the amount of _TiAl3 in the cBN sintered body becomes excessively small, resulting in a decrease in adhesion between the cBN grains and the binder phase and a decrease in the toughness of the cBN sintered body. may invite. For these reasons, I _Ti2CN /I _TiAl3 is more preferably 2.0 to 25.0, and even more preferably 5.0 to 15.0. The peak intensity ratio I _Ti2CN /I _TiAl3 can be controlled by adjusting the compounding ratio of the raw materials of the cBN sintered body.

Here, the peak intensity of Ti ₂ CN (I _Ti2CN ) and the peak intensity of TiAl ₃ (I _TiAl3 ) are determined by X-ray analysis (XRD) using CuKα radiation. Specifically, first, the diffraction peak of the {111} plane of cBN is set to 2θ=43.3, and this peak position (angle) is used as a reference. Then, the peak appearing at 2θ = 41.9 to 42.2° is Ti ₂ CN, the peak appearing at 2θ = 39.0 to 39.3° is TiAl ₃ , and the peak search is performed after removing the background. to obtain I _Ti2CN and I _TiAl3 , respectively.

In this embodiment, the binder phase preferably further contains Al ₂ O ₃ and has an average particle size of 0.9 μm to 2.5 μm. When the average particle size of Al ₂ O ₃ is less than 0.9 μm, it is necessary to reduce the particle size of Ti ₂ AlC or Ti ₃ AlC ₂ as a raw material, which is necessary for producing Al ₂ O ₃ . As a result, the ratio of Ti ₂ CN and TiAl ₃ generated in the cBN sintered body decreases, and the toughness of the cBN sintered body may decrease. On the other hand, if the average grain size of Al ₂ O ₃ exceeds 2.5 μm, cracks tend to occur due to fatigue accumulation originating from the Al ₂ O ₃ grains in the binder phase, and the toughness of the cBN sintered body decreases. There is a risk of

The average particle size of Al ₂ O ₃ in the binder phase can be determined from Al element and O element mapping by SEM-EDX (Energy Dispersive X-ray Spectroscopy). That is, by SEM-EDX, the portion where these two elements overlap is recognized as Al ₂ O ₃ , the grain size of each recognized grain is obtained by image analysis, and then the average grain size of Al ₂ O ₃ is calculated.

Specifically, first, the cross-sectional structure of the cBN sintered body is observed by SEM in the same manner as in the above-described <method for measuring the average particle size of cBN particles>, and a secondary electron image is obtained. Next, a mapping image of the Al element and the O element is acquired by EDX, and the overlapping portion of the Al element and the O element is identified as Al ₂ O ₃ and binarized by image processing to extract Al ₂ O ₃ .
In extracting the Al ₂ O ₃ portion in the image by image processing, first, this secondary electron image is displayed in monochrome with 256 gradations, where 0 is black and 255 is white, and the above-mentioned <average of cBN particles Particle size measurement method>, binarization processing is performed so that Al ₂ O ₃ becomes black.

After such a binarization process, a process is performed to separate the portions where the Al ₂ O ₃ particles are considered to be in contact with each other. For example, one image processing operation, watershed, is used to separate Al ₂ O ₃ particles that appear to be in contact. In this way, the portion corresponding to Al ₂ O ₃ is extracted by image processing from the image obtained by binarizing the secondary electron image.

The portion corresponding to Al ₂ O ₃ extracted by the above treatment (black portion) is subjected to particle analysis, and the maximum length of the portion corresponding to Al ₂ O ₃ particles is obtained. The determined maximum length is taken as the maximum length of each Al ₂ O ₃ particle, and this is taken as the diameter of each Al ₂ O ₃ particle. As a particle analysis for determining the maximum length, the Feret diameter is calculated for one Al ₂ O ₃ particle, and the larger of the two obtained lengths (horizontal length and vertical length) is Let the length value be the maximum length, which is the diameter of each Al ₂ O ₃ particle.

Next, each Al ₂ O ₃ particle is virtually regarded as a sphere, and the volume of each Al ₂ O ₃ particle is calculated from the obtained diameter. Based on the volume of each Al ₂ O ₃ particle, the integrated distribution of the particle size of the Al ₂ O ₃ particles is obtained. Specifically, for each Al ₂ O ₃ particle, the sum of its volume and the volume of Al ₂ O ₃ particles having a diameter equal to or smaller than that diameter is obtained as an integrated value. For each Al ₂ O ₃ particle, the vertical axis is the volume percentage [%], which is the ratio of the above integrated value of each Al ₂ O ₃ particle to the total volume of all Al ₂ O ₃ particles, and the horizontal axis is each Al _{2 Plot} the graph as the O3 particle diameter [μm]. The diameter (median diameter) at which the volume percentage is 50% is defined as the average particle diameter of the Al ₂ O ₃ particles in one image.

These treatments were performed on at least three secondary electron images, and the average value of the average particle size of the Al ₂ O ₃ particles obtained from each image was calculated as the average particle size of Al ₂ O ₃ in the binder phase [ μm]. When performing such particle analysis, the length (μm) per pixel is set using the scale value known in advance from the SEM. Also, in the particle analysis, in order to remove noise, regions smaller than 0.02 μm in diameter are not calculated as particles.

In this embodiment, TiAl ₃ in the binder phase may contain additional element M1 consisting of one or more of the group consisting of Si, Mg and Zn. That is, one or more of Si, Mg, and Zn may be present so as to be dispersed in TiAl ₃ in the binder phase. Thus, by including the additive element M1 in TiAl ₃ , fatigue fracture can be suppressed.

Further, when TiAl ₃ in the binder phase contains the additional element M1, the average of the regions where Ti and Al overlap in the respective mapping images of Ti, Al, and the additional element M1 by Auger electron spectroscopy (AES) S _TiAlM1 /S _TiAl , which is the ratio of the average area S _TiAlM1 of the overlapping region of Ti, Al, and the additive element M1 to the area S _TiAl , is preferably 0.05 to 0.98. Thereby, fatigue fracture can be suppressed more.

As an example of elemental mapping by AES, based on the observation results of the present invention chip 8 of the example described later, FIG. 5 shows where Ti element and Al element overlap, and FIG. Schematically shows overlapping portions. Comparing the two figures, as is apparent, the overlapping portion in FIG. 5 is part of the overlapping portion in FIG.

Here, it is not clear why the presence of one or more of Si, Mg, and Zn in TiAl ₃ in the binder phase makes it difficult for fatigue fracture to occur, but the following assumptions are made. there is

In the present invention, Ti ₂ AlC or Ti ₃ AlC ₂ is used as a raw material, and these can produce Ti ₂ CN and TiAl ₃ in the sintered body through ultra-high pressure sintering. When this TiAl ₃ and cBN react, TiAl ₃ decomposes and AlN is produced together with TiB ₂ .
This AlN has a low strength, and is particularly likely to be the starting point of fracture caused by the impact applied when the cBN sintered body is used as a drilling tool. However, by blending one or more of Si, Mg, and Zn as raw materials for the binder phase, Al generated by the decomposition of TiAl ₃ is mainly Since it becomes Al ₂ O ₃ , the generation of AlN can be suppressed. Furthermore, since the Ti—Al alloy produced by the decomposition of TiAl ₃ contains one or more of Si, Mg, and Zn, it is believed that the wear resistance is improved.

For these reasons, S _TiAlM1 /S _TiAl is preferably 0.05 to 0.98. When S _TiAlM1 /S _TiAl is less than 0.05, a large amount of AlN is generated in the cBN sintered body, and fatigue fracture is likely to occur. In addition, since this AlN is enlarged, cracks generated in the sintered body are likely to propagate, which may reduce the toughness. On the other hand, when S _TiAlM1 /S _TiAl exceeds 0.98, the formation of AlN is suppressed, but a large amount of Al ₂ O ₃ and TiCNO are formed in the binder phase due to oxygen originating from the raw material. Since Al ₂ O ₃ and TiCNO are likely to become starting points for causing fatigue fracture, there is a risk of lowering the toughness of the cBN sintered body. Therefore, S _TiAlM1 /S _TiAl is more preferably 0.15 to 0.50.

_The binder _phase in the hard layer ₃ of the present embodiment has been described above. ₂ , TiC, AlN, and Al ₂ O ₃ are preferably included. Furthermore, the hard layer 3 of the present embodiment may contain other alloys as inevitable impurities in addition to the composition described above within a range that does not impair the effects of the present invention.

In addition, the structure (composition) of the binder phase described above can be identified by the diffraction pattern obtained by the above-described X-ray analysis (XRD).

FIG. 2 shows a modification of the drilling tip of this embodiment. As shown in FIG. 2 , the hard layer 3 of this embodiment may include an intermediate layer 5 between the outermost layer 4 and the chip body 2 . That is, at least one intermediate layer 5 may be provided between the outermost layer 4 and the chip body 2 . Thereby, peeling of the outermost layer 4 can be prevented. That is, when the outermost layer 4 made of the above cBN sintered body is directly formed on the tip body 2, the difference in shrinkage between the tip body 2 and the outermost layer 4 made of a hard material such as cemented carbide may result in Depending on the thickness of the outermost layer 4, cracks may occur at the interface between the chip body 2 and the outermost layer 4 due to residual stress. In the modification shown in FIG. 2, since the intermediate layer 5 is provided between the outermost layer 4 and the chip body 2, the intermediate layer 5 functions as a stress relaxation layer. As a result, the occurrence of cracks can be suppressed, and peeling of the outermost layer 4 can be prevented.

The structure of the intermediate layer 5 is not particularly limited except that the content of the hard phase (diamond, cBN, or both) is smaller than that of the outermost layer 4 and that its hardness (Vickers hardness) is greater than that of the tip body 2. For example, the intermediate layer 5 is a cBN sintered body of a ceramic binder phase mainly composed of Ti carbonitride or boride, or a catalyst metal containing Al and at least one of Co, Ni, Mn, and Fe, and tungsten carbide. It may be a cBN sintered body sintered by. A metal additive containing at least one of W, Mo, Cr, V, Zr and Hf may be added to the metal catalyst. Further, the intermediate layer 5 can be composed of a polycrystalline diamond sintered body composed of diamond, cobalt, and tungsten carbide.

Here, the intermediate layer 5 preferably contains 10.0 to 70.0 vol% of cBN grains or diamond grains. When the content of cBN particles or diamond particles, which are hard particles, is less than 10.0 vol %, the intermediate layer 5 functions as a stress relaxation layer, but has low impact resistance and is highly likely to become the starting point of breakage. In addition, when the content of cBN particles or diamond particles exceeds 70.0 vol%, the difference in shrinkage rate between the tip body 2 and the intermediate layer 5 becomes large, and as a result, when the drilling tip is used as a tool, Due to the impact, cracks, which are starting points of tool breakage, are likely to occur near the interface between the tip body 2 and the intermediate layer 5 . Therefore, in order for the intermediate layer 5 to sufficiently function as a stress relaxation layer, the content of cBN grains or diamond grains in the intermediate layer 5 is preferably 10.0 to 70.0 vol %. More preferably, it is 30.0 to 60.0 vol%.

Although the intermediate layer 5 has a single-layer structure (one-layer structure) in the example shown in FIG. 2, the present embodiment is not limited to this. That is, in this embodiment, the intermediate layer 5 may have a multi-layer structure of two or more layers. However, when the intermediate layer 5 has a multi-layer structure of three or more layers, it is desirable to give a gradient to the hardness so that the Vickers hardness decreases from the outermost layer 4 side toward the tip body 2 side. That is, when the intermediate layer 5 has a multi-layered structure, it is desirable to adjust so that the content of cBN grains or diamond grains in the intermediate layer 5 gradually decreases from the outermost layer 4 side toward the tip body 2 side.

The thickness of the outermost layer 4 on the center line C is preferably 0.3 mm or more and 4.0 mm or less. If the thickness of the outermost layer 4 is less than 0.3 mm, the drilling tip may wear out quickly and have a short life. On the other hand, if the thickness of the outermost layer 4 is more than 4.0 mm, cracks are likely to occur due to residual stress during sintering, which may lead to sudden breakage during excavation. The thickness of the outermost layer 4 is more preferably 0.4 mm or more and 2.5 mm or less.

Also, the thickness of the entire intermediate layer 5 on the center line C is preferably 0.2 mm or more and 1.0 mm or less. When the thickness of the intermediate layer 5 is less than 0.2 mm, it is difficult to form a uniform layer, and thus it is difficult to absorb the residual stress during sintering. As a result, there is a possibility that the role of stress relaxation of the chip cannot be fulfilled. On the other hand, if the thickness of the intermediate layer 5 exceeds 1.0 mm, the thickness of the entire hard layer 3 (the outermost layer 4 and the intermediate layer 5) becomes large, and cracks tend to occur due to residual stress during sintering. Furthermore, as a result, there is a risk of causing sudden breakage during excavation. Therefore, the thickness of the entire intermediate layer 5 is more preferably 0.3 mm or more and 0.8 mm or less.

Next, a preferred method for manufacturing the drilling tip of this embodiment will be described.
A preferred method for manufacturing the drilling tip of the present embodiment includes the steps of obtaining a mixed powder obtained by mixing the raw material powder of the binder phase in the outermost layer 4 and cBN particles, the step of heat-treating the mixed powder, and the step of heat-treating the mixed powder. and a step of sintering the mixed powder, the raw material powder of the intermediate layer 5 and the chip body 2 .

First, raw material powder of the binder phase in the outermost layer 4 and cBN particles are mixed so as to have a predetermined composition to obtain a mixed powder. As the raw material powder of the binder phase of the outermost layer 4, for example, Ti ₂ AlC powder, Ti ₃ AlC ₂ powder, TiN powder, TiC powder, TiCN powder, and TiAl ₃ powder with a range of 1 μm to 500 μm can be used.

Next, the obtained mixed powder is subjected to heat treatment at, for example, 250° C. or higher and 900° C. or lower using a vacuum furnace. As a result, the adsorbed water on the raw material surface can be reduced without decomposing coarse-grained Ti ₂ AlC or Ti ₃ AlC ₂ into TiO ₂ and Al ₂ O ₃ . Al ₂ O ₃ produced can be reduced.

Here, by using coarse-grained Ti ₂ AlC or Ti ₃ AlC ₂ as the raw material powder, the reaction with oxygen during sintering is suppressed from progressing to the inside of the grains, and the sintered body after sintering contains Ti ₂ CN and TiAl ₃ can be produced. TiAl ₃ in the sintered body reacts with cBN to produce TiB ₂ and AlN, which can increase the bonding strength between cBN and the binder phase. Furthermore, by leaving TiAl ₃ , which is an alloy of Ti and Al, in the sintered body, the TiAl ₃ can compensate for the decrease in toughness due to coarse grains in the binder phase component. As a result, it is possible to obtain a drilling tip that is excellent in wear resistance and abrasive wear resistance during rock excavation, and highly resistant to damage factors such as breakage due to impact and vibration during rock excavation.

Next, the mixed powder after the heat treatment, the raw material powder of the intermediate layer 5, and the chip body 2 are charged into a normal ultra-high pressure sintering apparatus, and subjected to, for example, a pressure of 5 GPa or more and a temperature of 1600° C. or more. It is sintered for a predetermined time under ultra-high pressure and high temperature conditions. By integrally sintering the outermost layer 4, the intermediate layer 5 and the tip body 2 in this manner, the drilling tip of the present embodiment can be manufactured. In addition, by producing a cBN sintered body containing Ti ₂ CN and TiAl ₃ in the binder phase, fatigue wear due to impact and crushed rock surround the drilling tool. To obtain a hard layer 3 according to the present embodiment that is highly resistant to abrasive wear due to minute cutting action that occurs between rocks and rocks, and damage factors such as defects due to impacts and vibrations for breaking rocks. can be done.

Next, an excavation bit (excavation tool) to which the excavation tip 1 according to the present embodiment as described above is attached to the tip will be described.
As shown in FIG. 3, the drilling bit according to this embodiment has a bit body 11 that is approximately cylindrical with a bottom and centered on the axis O. As shown in FIG. In this embodiment, the bottomed portion of the bit body 11 serves as the tip portion (the upper portion in FIG. 3), and the drilling tip 1 is attached to this tip portion. The bit body 11 is made of, for example, steel. In the bit body 11, a female screw portion 12 is formed on the inner periphery of the cylindrical rear end portion (lower portion in FIG. 2). A drilling rod connected to the drilling rig is screwed into this female threaded portion 12, and the impact force and thrust toward the tip side in the direction of the axis O and the rotational force around the axis O are transmitted, whereby the drilling tip 1 Break the bedrock to form a borehole.

The tip of the bit body 11 has a slightly larger outer diameter than the rear end. In addition, a plurality of discharge grooves 13 extending parallel to the axis O are formed on the outer periphery of the tip portion at intervals in the circumferential direction. It is discharged to the rear end side through the discharge groove 13 .
A blow hole 14 is formed along the axis O from the bottom surface of the female screw portion 12 having a bottom. The blow hole 14 branches obliquely with respect to the axis O at the tip of the bit body 11 and opens at the tip face of the bit body 11 . With such an arrangement, a fluid, such as compressed air, supplied through the drilling rod is ejected to facilitate the ejection of debris.

Further, the tip surface of the bit body 11 is positioned on a circular face surface 15 centered on the axis O perpendicular to the axis O on the inner peripheral side, and on the outer periphery of this face surface 15. and a truncated conical gauge surface 16 directed toward the rear end side of the . The blow hole 14 opens on the face surface 15 and the tip of the discharge groove 13 opens on the outer peripheral side of the gauge surface 16 . A plurality of mounting holes 17 having a circular cross section are formed perpendicular to the face surface 15 and the gauge surface 16 so as to avoid openings of the blow hole 14 and the discharge groove 13, respectively. is formed in

The drilling tip 1 of this embodiment is embedded and attached to the attachment hole 17 as shown in FIG. Specifically, with the rear end portion 2A of the tip body 2 being buried in the mounting hole 17, the drilling tip 1 is fixed by interference fitting such as press fitting or shrink fitting, or by brazing. be done. The tip of the drilling tip 1 coated with the hard layer 3 protrudes from the face surface 15 and the gauge surface 16, and crushes the bedrock by the above-described impact force, thrust force and rotational force.

As shown in FIG. 3, the drilling tip 1 may be fixed at an angle with respect to the axis O of the drilling bit. does not necessarily match the axial direction of .

Although the drilling tip and drilling bit (drilling tool) according to the embodiments of the present invention have been described above, the present invention is not limited to this, and can be modified as appropriate without departing from the technical idea of the invention. . That is, each configuration and combination thereof in each embodiment of the present invention is an example, and addition, omission, replacement, and other modifications of the configuration are possible without departing from the gist of the present invention. Moreover, the present invention is not limited by the embodiments.

Next, examples of the drilling tip and drilling bit of the present invention will be given to demonstrate the effects of the present invention.

(Example 1)
First, as Example 1, an example of a drilling tip in which a cBN sintered body is applied to the outermost layer is given to demonstrate the effects of the present invention.

(1) Outermost Layer (1-1) Preparation of Raw Material Powder for Outermost Layer As a hard raw material for the outermost layer, cBN powder (cBN raw material) having an average particle size within the range of 0.5 to 35 μm was prepared.
In addition, Ti ₂ AlC powder and Ti ₃ AlC ₂ powder were prepared as raw material powders constituting the binder phase. Both the Ti ₂ AlC powder and the Ti ₃ AlC ₂ powder had an average particle size of 50 μm. In addition, TiN powder, TiC powder, TiCN powder, _TiAl3 powder, Al powder, _SiO2 powder, _MgSiO3 powder, and ZnO powder were separately prepared as raw material powders of the binder phase. Among these raw material powders, the average particle size of TiN powder, TiC powder, TiCN powder, and _TiAl3 powder is 0.3 μm to 0.9 μm, and the average particle size of _SiO2 powder, _MgSiO3 powder, and ZnO powder is 0. 0.015 μm to 0.9 μm. Table 1 shows the composition of the raw materials of the binder phase.

(1-2) First mixing Among these raw material powders for the outermost layer, powders other than powders containing the elements Si, Mg, and Zn are placed in a container lined with a cemented carbide with balls made of cemented carbide. It was filled with acetone, capped and mixed by a ball mill. The mixing time was set to 1 hour so as not to finely pulverize the raw material powder. Although not adopted in this embodiment, it is more preferable to use an ultrasonic stirrer to break up agglomerates of the raw material powder in the mixing process of the raw material powder.

(1-3) First Temporary Heat Treatment The raw material powder for the outermost layer obtained by the above steps was subjected to a preliminary heat treatment to evaporate the adsorbed water from the powder surface.
The preliminary heat treatment was performed in a vacuum atmosphere with a pressure of 1 Pa or less at the "heat treatment temperature after mixing" listed in Table 3. The reason is as follows.
If the heat treatment temperature in the preliminary heat treatment is less than 250°C, the adsorbed water may not be sufficiently dissociated from the raw material surface. As a result, Ti ₂ AlC or Ti ₃ AlC ₂ reacts with the moisture adsorbed to the raw material during ultra-high pressure and high temperature sintering, and is decomposed into TiO ₂ and Al ₂ O ₃ . The presence of Ti ₂ AlC and TiAl ₃ in the binding phase of the sintered body after bonding decreases, and the toughness of the sintered body decreases. On the other hand, if the heat treatment temperature in the preliminary heat treatment is higher than 900° C., Ti ₂ AlC or Ti ₃ AlC ₂ reacts with oxygen in the adsorbed water during the preliminary heat treatment and decomposes into TiO ₂ and Al ₂ O ₃ . In particular, TiAl ₃ disappears in the binder phase of the sintered body after ultra-high pressure and high temperature sintering, and the toughness of the sintered body is reduced. Therefore, the heat treatment temperature in the preliminary heat treatment is preferably 250 to 900.degree.

(1-4) Second mixing The raw material powder subjected to the first preliminary heat treatment, SiO ₂ powder, MgSiO ₃ powder, and ZnO powder are placed in a ball mill container lined with cemented carbide with balls made of cemented carbide. Filled with acetone and mixed. The mixing time was 1 hour so as not to pulverize the raw material powder. Although not performed in the present embodiment, it is more preferable to perform this mixing using an ultrasonic stirrer while crushing agglomeration of the raw material powder.

(2) Intermediate layer (2-1) Preparation of raw material powder for intermediate layer cBN powder (hard particles) with an average particle size of 6 μm, TiCN powder with an average particle size of 4 μm, and Al with an average particle size of 0.9 μm and powder were blended so that the content of cBN particles when the total amount of these was 100 vol % was the ratio shown in Table 2, wet-mixed, and dried. As a result, the raw material powder of the intermediate layer (type I) of the example of the present invention was obtained.
In addition, diamond particles (hard particles) with an average particle size of 10 μm and an average particle size of 2 μm, TaC powder with an average particle size of 4 μm, and Ta powder with an average particle size of 1 μm are added to the total amount of 100 vol %. The contents of the diamond particles were blended so that the content of the diamond particles was the ratio shown in Table 2, wet-mixed, and dried. As a result, raw material powder for the intermediate layer (type III) of the example of the present invention was obtained.
In addition, cBN powder (hard particles) with an average particle size of 6 μm, Ti ₂ AlC powder with an average particle size of 50 μm, and TiC powder with an average particle size of 4 μm are mixed, and the total amount of these is 100 vol%. The contents of cBN particles were blended so as to have the proportions shown in Table 2, wet-mixed, and dried. As a result, the raw material powder of the intermediate layer (type II) of the example of the present invention was obtained.

(2-2) Mixing These raw material powders for the intermediate layer were placed in a container lined with cemented carbide together with balls made of cemented carbide and acetone, covered, and mixed by a ball mill. The mixing time was set to 1 hour so as not to finely pulverize the raw material powder. Although not adopted in this embodiment, it is more preferable to mix the raw material powders for the intermediate layer while crushing agglomeration of the raw material powders using an ultrasonic stirrer.

(2-3) Temporary Heat Treatment The intermediate layer raw material powder obtained by the above mixing was subjected to a preliminary heat treatment to evaporate the adsorbed water from the powder surface.
The provisional heat treatment was performed at 600° C. in a vacuum atmosphere with a pressure of 1 Pa or less.

(3) Sintering Next, the raw material powder for the outermost layer and the raw material powder for the intermediate layer after temporary heat treatment are made of a cemented carbide containing 94 wt% WC and 6 wt% Co, and the surface in contact with the raw material powder is coated with TiN. It was integrally sintered together with the base body (chip body) under the conditions of sintering pressure: 6.0 GPa, sintering temperature: 1600° C., and sintering time: 20 minutes. As a result, drilling tips (invention example tips) 1 to 12 according to the present invention having a radius (2/D) of 4.5 mm and a length of 16 mm in the center line direction of the tip were produced. The distal end of the tip body (tip projection) was round with a radius of 5.75 mm. The thicknesses of the outermost layer and the intermediate layer in the center line direction of the chip are shown in Table 3.

Also, for comparison, drilling tips according to Comparative Examples 1 to 6 shown in Table 3 were manufactured. In producing the drilling tips of Comparative Examples 1 to 6, a cBN raw material having an average particle size of 1.0 to 4.0 μm was prepared as a hard raw material. In addition, raw material powders containing TiC, TiCN, etc., as shown in Table 1, were prepared as raw material powders constituting the binder phase. These were blended so as to have the composition shown in Table 1, and were mixed by a ball mill under the same conditions as in the above-described example of the present invention. The materials for the intermediate layer used in the comparative examples were the same as those used in the examples of the present invention.

After that, the raw material powder is subjected to preliminary heat treatment at a predetermined temperature in the range of 600° C. to 1200° C. (in Table 3, it is described as “heat treatment temperature after mixing”), and then WC: 94 wt%, Co: The substrate was made of 6 wt% cemented carbide and the surface in contact with the raw material powder was coated with TiN. Bonding time: sintered integrally under the conditions of 20 minutes. As a result, comparative drilling tips (comparative example tips) 1 to 6 shown in Table 3 were produced. The dimensions of the drilling tip of each comparative example were the same as those of the present invention example.

Table 3 shows the details of the drilling tips of the present invention examples and comparative examples obtained as described above. In addition, shown in Table 3, the content ratio and average particle size of cBN particles in the outermost layer, the peak intensity ratio I _Ti2CN /I _TiAl3 , the average particle size of Al ₂ O ₃ , the Si and Mg contained in TiAl ₃ in the binder phase and presence or absence of Zn element (presence or absence of Si, Mg and Zn elements by AES), and S _TiAlM1 /S _TiAl were measured and calculated by the same methods as described above.

Here, FIG. 4 shows the X-ray diffraction pattern of Inventive Example 3 in this example. As shown in FIG. 4, a Ti ₂ CN peak can be confirmed at 2θ=41.9 to 42.2°, and a TiAl ₃ peak can be confirmed at 2θ=39.0 to 39.3°.

Next, the obtained drilling tips of the present invention examples and comparative examples were attached to an NC lathe, and a wet cutting test was performed under the following conditions for evaluation.

<Conditions of wet cutting test>
Cutting speed: 150m/min
Cutting depth: 0.3mm
Feed rate: 0.1mm/rev
Work Material: Granite (produced in Takine), Shape Φ150mm×200mmL

<Evaluation method>
The amount of wear of the cutting edge and the state of the cutting edge were confirmed when the cutting length (cutting distance) was 750 m. However, the cutting edge was observed every 75 m of cutting length, and the presence or absence of chipping and the amount of wear were measured. If the amount of wear exceeded 2.3 mm (2300 μm), the cutting test was stopped at that point. In addition, the amount of wear was calculated by the following method.
Circular wear scars are formed on the specimen after the cutting test. This circular wear mark was approximated to a circle using image analysis software "ImageJ (published by the National Institutes of Health, USA)", and the long axis at this time was calculated as the amount of wear. Table 4 shows the results.

As is clear from Table 4, the drilling tips of the examples of the present invention all have a small amount of wear, so they are excellent in abrasive wear resistance. It has resistance to damage factors such as chipping. On the other hand, all of the drilling tips of the comparative examples either fractured or showed high wear amounts after a short cutting length. Therefore, all of the drilling tips of the comparative examples have low abrasive wear resistance and are easily chipped, making it difficult to use them as drilling tools.

(Example 2)
From among the drilling tips of the invention examples and the comparative examples shown in Table 3, seven invention examples (invention tips) 1, 3 and 11 and comparative examples (comparative example tips) 1, 2 and 5 were prepared. Then, a total of 7 drilling bits (bits 1 to 3 of the present invention, comparative example bits 1 to 3) were manufactured.

Next, these drilling bits were used to drill a plurality of drilling holes each having a drilling length of 4 m, and the total drilling length (m) up to the end of the life of the drilling tip was measured. In addition, the state of chip breakage was confirmed when the drilling chip reached the end of its life. Table 5 shows the results.
When the outermost layer of the drilling tip (button tip) was gradually worn away without causing damage such as chipping, it was judged to be normal wear. It was determined that the bit had reached the end of its life when these wear areas (amount of wear) increased and finally the gauge diameter became equal to the outer diameter of the bit body. On the other hand, it was determined that the bit had reached the end of its life when two or more tip bodies were chipped and the excavation speed was reduced as a result. The excavation conditions were as follows.

<Drilling conditions>
Drilling equipment: model number H205D manufactured by TAMROCK
Impact pressure: 160bar
Feed pressure: 80 bar
Rotation pressure: 55 bar
Water (water pressure: 18 bar) was supplied from the blow hole.

As shown in Table 5, the excavation length of bits 1 to 3 attached with comparative examples (comparative tips) 1, 2, and 5 did not exceed 100 m until the end of their life, and the drilling tips reached the end of their life due to chipping. did. On the other hand, the present invention bits 1 to 3 to which invention examples (comparative tips) 1, 3, and 11 were attached were all capable of excavating 100 m or more.

INDUSTRIAL APPLICABILITY According to the present invention, a drilling tip having excellent fatigue wear resistance and abrasive wear resistance and resistance to damage factors such as chipping due to impact and vibration for breaking rocks, and such a drilling tip. An attached drilling tool can be provided.

REFERENCE SIGNS LIST 1 drilling tip 2 tip body 2A rear end of tip body 2 2B tip of tip body 2 2a projection 2b recess 3 hard layer 4 outermost layer 5 intermediate layer 11 bit body C center line O axis of bit body 11 D tip body The diameter of the rear end portion 2A of 2 r1 The radius of the convex arc formed by the convex portion 2a in the cross section along the center line C r2 The radius P of the concave arc formed by the concave portion 2b in the cross section along the center line C Point of contact between convex portion 2a and concave portion 2b in cross section Q Center of arc formed by convex portion 2a in cross section along center line C L Straight line connecting point of contact P and center Q θ Straight line L in cross section along center line C angle with respect to the center line C

Claims (8)

1. A drilling tip configured to be attached to the tip of a drilling bit, comprising:
   a rear end portion having a cylindrical shape or a disc shape centered on the center line of the drilling tip; and a front end portion whose radius from the center line gradually decreases toward the front end side of the drilling tip from the rear end portion. a chip body having
   a hard layer covering the tip portion of the tip body;
   with
   The hard layer has an outermost layer made of a cBN sintered body having cubic boron nitride particles and a binder phase,
   A drilling tip, wherein the binder phase contains _Ti2CN and _TiAl3 .
2. In the X-ray diffraction pattern of the outermost layer, the peak intensity I _Ti2CN of Ti CN _appearing at a diffraction angle (2θ) of 41.9 to 42.2° and a diffraction angle (2θ) of 39.0 to 39 The drilling tip according to claim 1, characterized in that I _Ti2CN /I _TiAl3 , which is a ratio of the peak intensity I _TiAl3 of TiAl ₃ appearing at a position of 0.3°, is between 2.0 and 30.0.
3. The drilling tip according to claim 1 or 2, wherein the binder phase contains Al ₂ O ₃ and has an average grain size of 0.9 to 2.5 µm.
4. In the binder phase, the TiAl ₃ contains an additive element M1,
   The additive element M1 is one or more of the group consisting of Si, Mg and Zn,
   In the mapping images of Ti, Al, and the additive element M1 obtained by _Auger electron spectroscopy, the average area S of the regions where Ti and Al overlap. The drilling tip according to any one of claims 1 to 3, characterized in that the ratio of _TiAlM1 , S _TiAlM1 /S _TiAl , is 0.05 to 0.98.
5. the hard layer comprises an intermediate layer between the outermost layer and the tip body,
   A drilling tip according to any one of claims 1 to 4, characterized in that said intermediate layer contains 10.0 to 70.0 vol% of cubic boron nitride particles or diamond particles.
6. The drilling tip according to any one of claims 1 to 5, wherein the volume fraction of the cubic boron nitride particles in the outermost layer is 70.0 to 95.0 vol%.
7. The drilling tip according to any one of claims 1 to 6, wherein the cubic boron nitride particles in the outermost layer have an average particle diameter of 0.5 to 30.0 µm.
8. a drilling tip according to any one of claims 1 to 7;
   A drilling tool, comprising: a tool body that holds the drilling tip on a tip surface thereof and is rotatable about an axis.

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