WO2022210771A1 - Drilling tip and drilling tool - Google Patents

Drilling tip and drilling tool Download PDF

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Publication number
WO2022210771A1
WO2022210771A1 PCT/JP2022/015657 JP2022015657W WO2022210771A1 WO 2022210771 A1 WO2022210771 A1 WO 2022210771A1 JP 2022015657 W JP2022015657 W JP 2022015657W WO 2022210771 A1 WO2022210771 A1 WO 2022210771A1
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Prior art keywords
tip
drilling
cbn
outermost layer
layer
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PCT/JP2022/015657
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French (fr)
Japanese (ja)
Inventor
雅大 矢野
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三菱マテリアル株式会社
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Publication of WO2022210771A1 publication Critical patent/WO2022210771A1/en

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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
    • C04B35/583—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on boron nitride
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B10/00—Drill bits
    • E21B10/46—Drill bits characterised by wear resisting parts, e.g. diamond inserts

Definitions

  • the present invention relates to drilling tips and drilling tools.
  • This application claims priority based on Japanese Patent Application No. 2021-061363 filed in Japan on March 31, 2021, the content of which is incorporated herein.
  • 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.
  • Patent Document 1 such a polycrystalline A drilling tip coated with multiple hard layers of sintered diamond has been proposed.
  • 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.
  • 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.
  • 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.
  • diamond sintered bodies cannot be used in Fe-based or Ni-based mines because of their high affinity.
  • 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.
  • 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.
  • abrasive wear 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.
  • 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.
  • 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.
  • the binder phase in the cBN sintered body contains Ti 2 CN and Co 2 B and the XRD peaks of these Ti 2 CN and Co 2 B have a predetermined relationship, fatigue wear resistance and abrasive wear resistance are obtained. It has been found that it has excellent abrasion resistance and can improve resistance to the above-mentioned damage factors.
  • the present invention was made based on this finding, and the gist of the present invention is as follows.
  • a drilling tip 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.
  • 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 Co 2 B.
  • the peak intensity I Ti2CN of Ti CN appearing at a diffraction angle (2 ⁇ ) of 41.9 to 42.2° and the diffraction angle (2 ⁇ ) of I Ti2CN /I co2B , which is a ratio of the peak intensity I co2B of Co 2 B appearing at a position of 45.7 to 45.9°, may be 0.5 to 2.0.
  • the binder phase contains TiB 2 , and in the X-ray diffraction pattern of the outermost layer, the peak intensity of TiB 2 appears at a diffraction angle (2 ⁇ ) of 44.4 to 44.6° I TiB2 and I Co2B /I TiB2 , which is the ratio of the peak intensity I co2B of Co 2 B appearing at a diffraction angle (2 ⁇ ) of 45.7 to 45.9°, is 1.2 to 3.4. good too.
  • 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.
  • the volume fraction of the cubic boron nitride particles in the outermost layer may be 70.0 to 95.0 vol%.
  • the cubic boron nitride particles in the outermost layer may have an average particle diameter of 0.5 to 30.0 ⁇ m.
  • 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.
  • 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 9 of the present invention.
  • FIG. 1 is a cross-sectional view 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 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.
  • the chip body 2 is made of cemented carbide, for example.
  • 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.
  • 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 .
  • 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.
  • 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.
  • 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.
  • the angle ⁇ (°) 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 (°).
  • the angle ⁇ 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.
  • 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.
  • the tip portion 2B of the tip body 1 is covered with the hard layer 3 .
  • 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.
  • 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.
  • 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.
  • 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").
  • the hard layer 3 of the present embodiment may have a single-layer structure (FIG. 1) consisting of only the outermost layer 4, or may include an intermediate layer 5 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.
  • the average particle size of the cBN particles is not particularly limited, it is preferably in the range of 0.5 to 30.0 ⁇ m.
  • 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.
  • 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 ⁇ m, more preferably 0.5 to 3.0 ⁇ m, 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.
  • 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 .
  • the average particle diameter of cBN particles and the content of cBN particles in the cBN sintered body can be obtained as follows.
  • the average particle diameter of cBN particles can be determined 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.
  • SEM scanning electron microscope
  • 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.
  • 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. .
  • a region of about 0.5 ⁇ m ⁇ 0.5 ⁇ m is selected as the region for obtaining the pixel value of the cBN grain portion, and the average value obtained from at least three different locations within the same image region is calculated as the above-mentioned cBN grain. It is preferable to use the peak value of the pixel value. Then, a region of about 0.2 ⁇ m ⁇ 0.2 ⁇ m to about 0.5 ⁇ m ⁇ 0.5 ⁇ m 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.
  • 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.
  • 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. .
  • 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. ( ⁇ m), 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 ( ⁇ m, this average particle size is called D50).
  • the length ( ⁇ m) per pixel is set using the scale value known from the SEM in advance.
  • 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 ⁇ m, the observation area is preferably about 15 ⁇ m ⁇ 15 ⁇ m, for example.
  • 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.
  • the observation area used for image processing is preferably an area of about 15 ⁇ m ⁇ 15 ⁇ m.
  • the binder phase in the cBN sintered body contains Ti2CN and Co2B .
  • Ti 2 CN and Co 2 B 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.
  • 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.
  • I Ti2CN /I co2B which is the ratio of the peak intensity I Ti2CN of Ti 2 CN to the peak intensity I co2B of Co 2 B, is 0.5 to 2.0 is preferred.
  • the peak intensity I Ti2CN of Ti CN that appears at a diffraction angle (2 ⁇ ) of 41.9 to 42.2°, I Ti2CN /I co2B , which is the ratio of the peak intensity I co2B of Co 2 B appearing at a diffraction angle (2 ⁇ ) of 45.7 to 45.9° is preferably 0.5 to 2.0. .
  • the ratio of the respective peak intensities in XRD is within the range of 0.5 to 2.0. 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.
  • the mechanism by which Co 2 B is generated in the cBN sintered body is presumed to be as follows. First, during sintering under ultrahigh pressure, TiAlCo is produced by reacting Ti2AlC or Ti3AlC2 with Co, and Co2B is produced by reacting this TiAlCo with cBN. . And it is assumed that TiB 2 is also produced when this Co 2 B is produced. Based on this assumption, it is considered that if I Ti2CN /I Co2B is less than 0.5, the ratio of Co 2 B generated by the reaction between TiAlCo and cBN in the sintered body increases.
  • I Ti2CN /I Co2B is more preferably 0.8 to 1.5.
  • the peak intensity ratio I Ti2CN /I Co2B can be controlled by adjusting the compounding ratio of the raw materials of the cBN sintered body.
  • XRD X-ray analysis
  • the binder phase further contains TiB 2 , and in the X-ray diffraction pattern, the peak intensity I TiB2 of TiB 2 appearing at a diffraction angle (2 ⁇ ) of 44.4 to 44.6°, and the above-mentioned I Co2B /I TiB2 , which is the ratio of the peak intensity I co2B of Co 2 B, is preferably 1.2 to 3.4.
  • I Co2B /I TiB2 is less than 1.2, TiB 2 with low toughness is excessively generated in the sintered body, and coarse TiB 2 is formed. As a result, this coarse TiB 2 may become a starting point of fracture during rock excavation, and may cause damage such as the chipping described above.
  • I Co2B /I TiB2 is more preferably 1.5 to 2.5, and even more preferably 1.6 to 2.0.
  • the peak intensity ratio I Co2B /I TiB2 can be controlled by adjusting the compounding ratio of the raw materials of the cBN sintered body.
  • the binder phase in the hard layer 3 of the present embodiment preferably contains one or more of AlN and Al 2 O 3 in addition to TiB 2 .
  • 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.
  • 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.
  • 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-described 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.
  • 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.
  • the intermediate layer 5 can also be composed of a polycrystalline diamond sintered body made of diamond, cobalt, tungsten carbide, or the like.
  • the intermediate layer 5 preferably contains 10.0 to 70.0 vol% of cBN grains or diamond grains.
  • 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.
  • 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 to 60 vol%.
  • 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.
  • 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.
  • the thickness of the intermediate layer 5 is less than 0.2 mm, it is difficult to form a uniform layer, and thus it becomes difficult to absorb residual stress during sintering. As a result, there is a possibility that the role of stress relaxation of the chip cannot be fulfilled.
  • 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.
  • a preferred method for manufacturing the drilling tip of this 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 .
  • 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.
  • the raw material powder of the binder phase of the outermost layer 4 for example, Ti 2 AlC powder, Ti 3 AlC 2 powder, Co powder, TiN powder, TiC powder, TiCN powder, and TiAl 3 powder with a range of 1 ⁇ m to 500 ⁇ m are used. can be done.
  • 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.
  • 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 , and oxidation of Co during ultrahigh pressure and high temperature sintering can be suppressed. can be reduced.
  • Ti 2 AlC or Ti 3 AlC 2 and Co can be reacted first.
  • 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 can be produced.
  • the raw material Co first reacts with Ti 2 AlC or Ti 3 AlC 2 to produce TiAlCo, which then reacts with cBN to produce Co 2 B, TiB 2 and AlN. This can increase the bond strength between the cBN and the binder phase.
  • the decrease in toughness due to coarse grains in the binder phase component can be compensated for by the effect of improving toughness due to fine Co 2 B dispersed and generated in the sintered body. 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.
  • 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.
  • 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.
  • the intermediate layer 5 and the tip body 2 in this manner, the drilling tip of the present embodiment can be manufactured.
  • a cBN sintered body containing Ti 2 CN and Co 2 B in the binder phase fatigue wear due to impact and crushed rock surrounding the excavating tool can cause the hard components of the rock to affect the tool.
  • the hard layer 3 according to the present embodiment which is highly resistant to abrasive wear due to minute cutting action generated between the cutting edge and the rock, and damage factors such as chipping due
  • the drilling bit 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.
  • 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.
  • 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.
  • 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.
  • the drilling tip 1 may be fixed at an angle with respect to the axis O of the drilling bit, the axial direction of the centerline C of the drilling tip 1 coincides with the axis O of the drilling bit. does not necessarily match the axial direction of .
  • 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.
  • 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.
  • Outermost Layer (1-1) Preparation of Raw Material Powder for Outermost Layer
  • cBN powder cBN raw material having an average particle size within the range of 0.5 to 35 ⁇ m was prepared.
  • raw material powders constituting the binder phase Ti 2 AlC powder or Ti 3 AlC 2 powder and Co raw material were prepared. Both the Ti 2 AlC powder and the Ti 3 AlC 2 powder had an average particle size of 50 ⁇ m.
  • the Co raw material had an average particle size of 1 ⁇ m.
  • TiN powder, TiC powder, TiCN powder, and TiAl3 powder were separately prepared as raw material powders of the binder phase. The average particle size of these TiN powder, TiC powder, TiCN powder and TiAl 3 powder was 0.3 ⁇ m to 0.9 ⁇ m. Table 1 shows the composition of the raw materials of the binder phase.
  • diamond particles hard particles with an average particle size of 10 ⁇ m and an average particle size of 2 ⁇ m
  • WC powder with an average particle size of 2.1 ⁇ m are added together. They were mixed so that the content of diamond particles at 100 vol % would be 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.
  • Ti 2 AlC or Ti 3 AlC 2 reacts with the moisture adsorbed to the raw material during the ultra-high pressure and high temperature sintering, and is decomposed into TiO 2 and Al 2 O 3 .
  • the presence of Ti 2 AlC in the binder phase of the sintered body after bonding is reduced, and the toughness of the sintered body is lowered.
  • 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 .
  • the heat treatment temperature in the preliminary heat treatment is preferably 250 to 900.degree.
  • the raw material powder for the outermost layer and the raw material powder for the intermediate layer after the temporary heat treatment are sintered together with a base (tip body) made of a cemented carbide containing 94 wt% WC and 6 wt% Co, under a sintering pressure of: It was integrally sintered under the conditions of 6.0 GPa, sintering temperature: 1600° C., and sintering time: 20 minutes.
  • 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 leading end of the tip body had a round shape 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.
  • drilling tips according to Comparative Examples 1 to 5 shown in Table 3 were manufactured.
  • a cBN raw material having an average particle size of 1.0 to 4.0 ⁇ m was prepared as a hard raw material.
  • 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.
  • the raw material powder is subjected to preliminary heat treatment at a predetermined temperature in the range of 600° C. to 900° C. (in Table 3, it is described as “heat treatment temperature after mixing”), and then WC: 94 wt%, Co: Together with a substrate made of 6 wt% cemented carbide, it is charged into an ultra-high pressure sintering apparatus and integrally sintered under the conditions of sintering pressure: 5.0 GPa, sintering temperature: 1600 ° C., sintering time: 20 minutes. tied.
  • sintering pressure 5.0 GPa
  • sintering temperature 1600 ° C.
  • sintering time 20 minutes. tied.
  • Table 3 shows the details of the drilling tips of the present invention examples and comparative examples obtained as described above.
  • the content ratio and average particle diameter of the cBN particles in the outermost layer, the peak intensity ratio I Ti2CN /I Co2B , and the peak intensity ratio I Co2B /I TiB2 shown in Table 3 were measured and calculated by the same methods as described above. .
  • FIG. 4 shows the X-ray diffraction pattern of Inventive Example 9 in this example.
  • ⁇ 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 ⁇ m), 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.
  • 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.
  • 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, 6 and 7 and comparative examples (comparative example tips) 2, 4 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.
  • Drilling equipment model number H205D manufactured by TAMROCK Impact pressure: 160bar Feed pressure: 80 bar Rotation pressure: 55bar Water (water pressure: 18 bar) was supplied from the blow hole.
  • a drilling tip that is excellent in fatigue wear resistance and abrasive wear resistance, and has resistance to damage factors such as chipping due to impact and vibration for breaking rocks, and provides such a drilling tip.
  • a drilling tool can be provided with an attached tip.

Abstract

This drilling tip comprises: a tip body (2) having a proximal end part (2A) and a distal end part (2B), forming a columnar shape or disc shape centered on a center line (C) of a tip; and a hard layer (3) covering the distal end part 2B. The hard layer (3) has an outermost layer (4) composed of a cBN sintered compact having a phase bonded with cubic crystal boron nitride particles, and the bonded phase contains Ti2CN and Co2B.

Description

掘削チップおよび掘削工具drilling tips and drilling tools
　本発明は、掘削チップおよび掘削工具に関するものである。
　本願は、２０２１年３月３１日に、日本に出願された特願２０２１－０６１３６３号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to drilling tips and drilling tools.
This application claims priority based on Japanese Patent Application No. 2021-061363 filed in Japan on March 31, 2021, the content of which is incorporated herein.
　掘削工具の先端部に取り付けられて掘削を行う掘削チップとして、打撃掘削用ビットの長寿命化を図るため、超硬合金よりなるチップ本体の基体先端部に、このチップ本体よりも硬質な多結晶ダイヤモンドの焼結体よりなる硬質層が被覆された掘削チップが知られている。例えば、特許文献１には、円柱状の後端部と、半球状をなして先端側に向かうに従い外径が小さくなる先端部と、を有するチップ本体の上記先端部に、このような多結晶ダイヤモンド焼結体の硬質層を多層に被覆した掘削チップが提案されている。 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.
　また、掘削チップとして、露天採掘や長壁式採掘に用いられるドラム式掘削装置の回転ドラムの外周に取り付けられるピックの先端に接合された掘削チップが知られている。特許文献２には、チップ本体の略円錐状の先端部をダイヤモンドおよび／または立方晶窒化ホウ素により被覆した掘削チップが提案されている。特許文献３には、チップ本体の略円錐状の先端部を被覆する最外層が、多結晶ダイヤモンド、多結晶立方晶窒化ホウ素、単結晶ダイヤモンド、および立方晶窒化ホウ素複合材から選択されることが提案されている。 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.
　立方晶窒化ホウ素焼結体について、特許文献４には、強度および靱性を向上するために、Ａｌ２Ｏ、ＡｌＢ２、ＡｌＮ、ＴｉＢ２、およびＴｉＮを含有する結合相を備える立方晶窒化ホウ素焼結体で構成した切削工具が提案されている。 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.
米国特許第４６９４９１８号明細書（Ｂ）U.S. Pat. No. 4,694,918 (B) 米国特許第６０５１０７９号明細書（Ｂ）U.S. Pat. No. 6,051,079 (B) 欧州特許出願公開第２０５３１９８号明細書（Ａ）European Patent Application Publication No. 2053198 (A) 日本国特開平８－１９７３０７号公報（Ａ）Japanese Patent Laid-Open No. 8-197307 (A)
　しかしながら、多結晶ダイヤモンド焼結体は、超硬合金に比べて耐摩耗性は高いものの、靱性が低いために耐欠損性に乏しい。そのため、超硬岩層の掘削においては突発的な硬質層のチッピングや欠損が起きることがある。また、ダイヤモンド焼結体は、Ｆｅ系やＮｉ系の鉱山では、親和性が高いために使用することができない。さらに、ダイヤモンド焼結体の耐熱温度も７００℃程度であるため、これより高温に晒される条件ではダイヤモンド焼結体は使用できない。例えば、ドライ環境で行われる露天採掘のように７００℃以上の高温となる掘削条件下では、ダイヤモンドが黒鉛化して耐摩耗性が低下してしまう。 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.
　また、立方晶窒化ホウ素焼結体は、Ｆｅ系やＮｉ系の鉱山では親和性が低いものの、ダイヤモンドと比較して硬さが劣る。特許文献４に記載の立方晶窒化ホウ素焼結体は、硬さが比較的低く、耐摩耗性と耐欠損性が不十分であるため、掘削工具への適用は困難であった。 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.
　また、従来では、立方晶窒化ホウ素焼結体を岩石掘削用の掘削工具とした場合、繰り返し加わる衝撃による疲労摩耗に対する耐性（耐疲労摩耗性）、およびアブレッシブ摩耗に対する耐性（耐アブレッシブ摩耗性）を十分に確保できなかった。さらに、岩石を破壊するための衝撃や振動による欠損などの損傷要因に対する耐性についても、十分ではない。
なおここでいう「アブレッシブ摩耗」とは、破砕した岩石が堀削工具の周囲を取り巻く中で、硬質成分が工具刃先と岩石の間に入り込むことで生じる微小な切削作用による摩耗のことを指す。 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.
　掘削工具は、地面や岩盤を掘り穿つための工具である。一方、地中の岩石は、その成分や強度は均一ではなく、脆性材料である。そのため、切り込み、削り取る性能を重視する切削工具とは異なり、掘削工具は、岩石を破壊するための衝撃や振動に耐えうる性能、さらにこの破壊した岩石を効率よく取り除くための回転に耐えうる性能が必要である。 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.
　すなわち、掘削工具に用いられる材料には、耐疲労摩耗性、耐アブレッシブ摩耗性、さらには、岩石を破壊するための衝撃や振動による欠損などの損傷要因に対する耐性が求められている。 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.
　本発明は、このような背景の下になされたもので、耐疲労摩耗性、耐アブレッシブ摩耗性に優れ、さらに、岩石を破壊するための衝撃や振動による欠損などの損傷要因に対する耐性を有する掘削チップを提供するとともに、このような掘削チップを取り付けた掘削工具を提供することを目的としている。 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.
　本発明者らは、掘削チップの材料としてｃＢＮ焼結体に着目し検討した。その結果、ｃＢＮ焼結体における結合相が、Ｔｉ２ＣＮとＣｏ２Ｂを含有するとともに、これらＴｉ２ＣＮとＣｏ２ＢのＸＲＤピークに所定の関係があるとき、耐疲労摩耗性、耐アブレッシブ摩耗性に優れ、さらに上記損傷要因に対する耐性を向上させることができるという知見を得た。
　本発明は、この知見に基づきなされたものであって、本発明の要旨は以下の通りである。 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 Co 2 B and the XRD peaks of these Ti 2 CN and Co 2 B have a predetermined relationship, fatigue wear resistance and abrasive wear resistance are obtained. It has been found that it has excellent abrasion resistance and can improve resistance to the above-mentioned damage factors.
The present invention was made based on this finding, and the gist of the present invention is as follows.
　本発明の一態様の掘削チップは、掘削ビットの先端部に取り付けられるように構成された掘削チップであって、前記掘削チップの中心線を中心（軸）とした円柱形状または円板形状をなす後端部と、前記後端部から前記掘削チップの先端側に向かうに従い前記中心線からの半径が漸次小さくなる先端部とを有するチップ本体と、前記チップ本体の前記先端部を被覆する硬質層と、を備え、前記硬質層は、立方晶窒化ホウ素粒子と結合相とを有するｃＢＮ焼結体からなる最外層を有し、前記結合相は、Ｔｉ２ＣＮとＣｏ２Ｂを含有することを特徴とする。 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 Co 2 B. Characterized by
　上記掘削チップにおいて、前記最外層のＸ線回折パターンにおいて、回折角（２θ）が４１．９～４２．２°の位置に出現するＴｉ２ＣＮのピーク強度ＩＴｉ２ＣＮと、回折角（２θ）が４５．７～４５．９°の位置に出現するＣｏ２Ｂのピーク強度Ｉｃо２Ｂとの比であるＩＴｉ２ＣＮ／Ｉｃо２Ｂが０．５～２．０であってもよい。 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 co2B , which is a ratio of the peak intensity I co2B of Co 2 B appearing at a position of 45.7 to 45.9°, may be 0.5 to 2.0.
　上記掘削チップにおいて、前記結合相は、ＴｉＢ２を含有し、前記最外層のＸ線回折パターンにおいて、回折角（２θ）が４４．４～４４．６°に出現するＴｉＢ２のピーク強度ＩＴｉＢ２と、回折角（２θ）が４５．７～４５．９°の位置に出現するＣｏ２Ｂのピーク強度Ｉｃо２Ｂとの比であるＩＣｏ２Ｂ／ＩＴｉＢ２が１．２～３．４であってもよい。 In the drilling tip, the binder phase contains TiB 2 , and in the X-ray diffraction pattern of the outermost layer, the peak intensity of TiB 2 appears at a diffraction angle (2θ) of 44.4 to 44.6° I TiB2 and I Co2B /I TiB2 , which is the ratio of the peak intensity I co2B of Co 2 B appearing at a diffraction angle (2θ) of 45.7 to 45.9°, is 1.2 to 3.4. good too.
　上記掘削チップにおいて、前記硬質層は、前記最外層と前記チップ本体との間に、中間層を備え、前記中間層が、１０．０～７０．０ｖｏｌ％の立方晶窒化ホウ素粒子またはダイヤモンド粒子を含有していてもよい。 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.
　上記掘削チップにおいて、前記最外層における、前記立方晶窒化ホウ素粒子の体積率は、７０．０～９５．０ｖоｌ％であってもよい。 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%.
　上記掘削チップにおいて、前記最外層における、前記立方晶窒化ホウ素粒子の平均粒径は、０．５～３０．０μｍであってもよい。 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.
　また、本発明の一態様の掘削工具は、上述の掘削チップと、先端面において前記掘削チップを保持し、軸線回りに回転させられる工具本体と、を備えることを特徴とする。 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.
　本発明によれば、耐疲労摩耗性、耐アブレッシブ摩耗性に優れ、さらに、岩石を破壊するための衝撃や振動による欠損などの損傷要因に対する耐性を有する掘削チップ、ならびに、このような掘削チップを取り付けた掘削工具を提供することができる。 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.
図１は、本発明の掘削チップの実施形態を示すチップの中心線に沿った断面図である。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. 図２は、本実施形態の掘削チップの変形例を示すチップの中心線に沿った断面図である。FIG. 2 is a cross-sectional view along the centerline of the tip showing a modification of the drilling tip of the present embodiment. 図３は、図１に示す本実施形態の掘削チップをビット本体の先端部に取り付けた、本発明の掘削ビットの実施形態を示すビット本体の軸線に沿った断面図である。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. 図４は、本発明例９のＸ線回折パターンである。FIG. 4 is an X-ray diffraction pattern of Example 9 of the present invention.
　以下、本発明の掘削チップおよび掘削工具について、より詳細に説明する。なお、以下に記載する「～」を挟んで記載される数値限定範囲には、下限値および上限値がその範囲に含まれる。「未満」、「超」と示す数値には、その値が数値範囲に含まれない。 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.
　図１は、本発明の掘削チップの実施形態を示す断面図であり、図２は、本実施形態の掘削チップの変形例を示すチップの中心線に沿った断面図である。図３は、本実施形態の掘削チップを取り付けた本発明の掘削ビットの実施形態を示す断面図である。
　本発明の掘削チップの形状は、一端が丸まった円筒形状である。チップの中心線Ｃは円筒形状の軸方向に平行で、かつ、掘削チップの中心を通る直線である。掘削チップの中心は、掘削チップを軸方向から見た場合（平面視した場合）の中心である。 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).
　本実施形態の掘削チップ１は、チップの中心線Ｃを中心とした円柱形状または円板形状をなす後端部２Ａと、この後端部２Ａから先端側に向かうに従い中心線Ｃからの半径が漸次小さくなる先端部２Ｂとが一体に形成されたチップ本体２と、このチップ本体２の先端部２Ｂの表面を被覆する硬質層３とを備えている。チップ本体２は、例えば、超硬合金よりなる。また、硬質層３は、チップ本体２よりも硬度（ビッカース硬さ）の高い材料からなる。なお、硬質層３は、図１に示すように、最外層４からなる単層構造としてもよいし、図２に示すように、最外層４とチップ本体２との間に、中間層５を備えるような多層構造としてもよい。 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.
　チップ本体２の先端部２Ｂは、図１に示すように、中心線Ｃに沿った断面において、表面が先端側に凸となる凸円弧状をなす凸部２ａと、表面が凸部２ａの断面の凸円弧に接し、凹円弧状をなす凹部２ｂとを有している。具体的には、この凹部２ｂは、図１に示すように、表面が凸部２ａの断面の凸円弧と、接点Ｐにおいて接しており、かつ、チップ本体２の後端側に向かうに従い外周側に広がるよう形成されている。本実施形態においては、凸部２ａの表面は中心線Ｃ上に中心を有する凸球面状に形成されるとともに、上記断面において凹部２ｂの表面は、チップ本体２の後端部２Ａの外周面に鈍角に交差している。 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.
　チップ本体２の後端部２Ａの直径Ｄ（ｍｍ）は、掘削に使用する際の衝撃荷重と、硬質層３とチップ本体２との界面に生じる残留応力の緩和とのバランスを図る観点から適宜決定してよく、例えば、８ｍｍ～２０ｍｍの範囲としてよい。 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.
　チップ本体２の後端部２Ａの直径Ｄ（ｍｍ）に対して、中心線Ｃに沿った断面における凸部２ａの凸円弧の半径ｒ１（ｍｍ）がなす比ｒ１／Ｄは、０．１～０．６５の範囲内とすることが好ましい。ｒ１／Ｄを当該範囲内とすることで、硬質層３とチップ本体２との界面への残留応力を一層確実に緩和することができるとともに、硬質層３の厚みを十分に確保することができ、その結果、掘削工具の長寿命化を図ることが可能となる。 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.
　また、チップ本体２の後端部２Ａの直径Ｄ（ｍｍ）に対して、中心線Ｃに沿った断面における凹部２ｂの凹円弧の半径ｒ２（ｍｍ）がなす比ｒ２／Ｄは、０．０５～３．０の範囲内とすることが好ましい。ｒ２／Ｄを当該範囲内とすることで、同様に、硬質層３とチップ本体２との界面への残留応力を一層確実に緩和することができるとともに、硬質層３の厚みを十分に確保することができ、その結果、掘削工具の長寿命化を図ることが可能となる。 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.
　さらに、中心線Ｃに沿った断面において、凸部２ａと凹部２ｂとの接点Ｐと、凸部２ａの凸円弧の中心Ｑとを結ぶ直線Ｌが中心線Ｃに対してなす角度θ（°）は、２０（°）～９０（°）の範囲内としてよい。角度θを当該範囲内とすることで、硬質層３とチップ本体２との界面への残留応力を一層確実に緩和することができるとともに、硬質層３の厚みを十分に確保することができ、その結果、掘削工具の長寿命化を図ることが可能となる。
　なお、本明細書でいう「中心線Ｃに沿った断面」とは、中心線Ｃからの距離が０．１（ｍｍ）以内の範囲で中心線Ｃに沿った断面であればよい。 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.
　本実施形態では、チップ本体１の先端部２Ｂに硬質層３が被覆されている。図１に示すように、硬質層３の後端部３Ａは、チップ本体２の後端部２Ａの先端側に連なっている。
さらに、硬質層３の後端部３Ａの外周面は、中心線Ｃを中心とした、チップ本体２の後端部２Ａと等しい直径Ｄ（ｍｍ）の円筒面状とされている。一方、硬質層３の先端部３Ｂの表面は、後端部３Ａの外周面に滑らかに連なり、かつ上記中心Ｑを中心とした凸半球面状とされている。すなわち、本実施形態の掘削チップ１は、いわゆるボタンチップである。
また、硬質層３の厚さは、少なくとも上記接点Ｐよりも先端側では略均一とされていてもよい。 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.
　本実施形態の硬質層３は、立方晶窒化ホウ素焼結体（以下、「ｃＢＮ焼結体」ともいう）からなる最外層４を有する。ここで、本実施形態の硬質層３は、上記のとおり、最外層４のみからなる単層構造（図１）としてもよいし、最外層４とチップ本体２との間に中間層５を備えるような多層構造（図２）としてもよい。
　最外層４を構成するｃＢＮ焼結体は、立方晶窒化ホウ素粒子（以下、「ｃＢＮ粒子」ともいう）と、各ｃＢＮ粒子を互いに結合する結合相を有する。 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 the present embodiment may have a single-layer structure (FIG. 1) consisting of only the outermost layer 4, or may include an intermediate layer 5 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.
　ｃＢＮ粒子の平均粒径は、特に限定されるものではないが、０．５～３０．０μｍの範囲であることが好ましい。このような粒径範囲を有する硬質なｃＢＮ粒子がｃＢＮ焼結体内に分散することにより、最外層４に高い耐欠損性を付与することができる。
具体的には、掘削時に、最外層４表面からｃＢＮ粒子が脱落することにより生じる凹凸を起点としたチッピングの発生を抑制することができる。それに加え、掘削時に、最外層４に加わる応力により引き起こされるｃＢＮ粒子と結合相との界面から進展するクラック、またはｃＢＮ粒子を貫通して進展するクラックの伝播を、ｃＢＮ粒子により抑制することができる。ｃＢＮ粒子の平均粒径は０．５～８．０μｍであることがより好ましく、０．５～３．０μｍであることがさらに好ましいが、これに限定されない。 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.
　ｃＢＮ焼結体に占めるｃＢＮ粒子の含有量（ｖｏｌ％）は、特に限定されるものではないが、７０～９５ｖｏｌ％の範囲であることが好ましい。ｃＢＮ焼結体に占めるｃＢＮ粒子の含有量が過度に低い場合、ｃＢＮ粒子の量が少ないので、ｃＢＮ粒子同士が接触し結合相と十分に反応できない未焼結な部分は少なくなるが、その一方で、最外層４のｃＢＮ焼結体の硬さが低下し、耐摩耗性や耐欠損性が劣化する場合がある。一方、ｃＢＮ粒子の含有量が過度に高い場合には、焼結体中にクラックの起点となる空隙が生成しやすくなり、耐欠損性が低下する場合がある。そのため、ｃＢＮ焼結体に占めるｃＢＮ粒子の含有量は、７０～９５ｖｏｌ％の範囲であることが好ましい。より好ましくは７０～９０ｖｏｌ％であり、さらに好ましくは７５～８５ｖｏｌ％であるがこれに限定されない。なお、ｃＢＮ粒子の含有量は、最外層４の形成時にｃＢＮ粒子粉末と結合相形成用原料粉末との混合比率を調整することにより調整できる。 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 .
　ここで、ｃＢＮ粒子の平均粒径、およびｃＢＮ焼結体に占めるｃＢＮ粒子の含有量は、以下のとおりにして求めることができる。 Here, the average particle diameter of cBN particles and the content of cBN particles in the cBN sintered body can be obtained as follows.
＜ｃＢＮ粒子の平均粒径の測定方法＞ <Method for measuring average particle size of cBN particles>
　ここで、ｃＢＮ粒子の平均粒径は、以下のとおりにして求めることができる。
　ｃＢＮ焼結体の断面を鏡面加工し、鏡面加工した面に対して走査型電子顕微鏡（ＳｃａｎｎｉｎｇＥｌｅｃｔｒｏｎＭｉｃｒｏｓｃｏｐｅ：以下、ＳＥＭという）による組織観察を実施し、二次電子像を得る。次に、得られた画像内のｃＢＮ粒子の部分を画像処理にて抜き出し、画像解析より求めた各粒子の最大長を基に、後述する平均粒径を算出する。 Here, the average particle diameter of cBN particles can be determined 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.
　ここで、画像内のｃＢＮ粒子の部分を画像処理にて抜き出すにあたり、ＣＢＮ粒子と結合相とを明確に判断するため、画像は０を黒、２５５を白の２５６階調のモノクロで表示し、ｃＢＮ粒子部分の画素値のピーク値（ｖ）と結合相部分の画素値のピーク値（ｗ）に対して、（ｗ－ｖ）／２＋ｖで算出された値を閾値として２値化処理を行う。 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. .
　ｃＢＮ粒子部分の画素値を求めるための領域として、例えば、０．５μｍ×０．５μｍ程度の領域を選択し、同一画像領域内から少なくとも異なる３個所より求めた平均の値をｃＢＮ粒子の前述の画素値のピーク値とすることが好ましい。そして、結合相部分の画素値を求めるための領域として、０．２μｍ×０．２μｍ程度から０．５μｍ×０．５μｍ程度の領域を選択し、同じく、同一画像領域内から少なくとも異なる３個所より求めた平均の値を結合相の前述の画素値のピーク値とすることが好ましい。 For example, a region of about 0.5 μm×0.5 μm is selected as the region for obtaining the pixel value of the cBN grain portion, and the average value obtained from at least three different locations within the same image region is calculated as the above-mentioned cBN grain. It is preferable to use the peak value of the pixel value. 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.
　なお、２値化処理後はｃＢＮ粒同士が接触していると考えられる部分を切り離すような処理、例えば、ウォーターシェッド（ｗａｔｅｒｓｈｅｄ）画像処理を用いて接触していると思われるｃＢＮ粒同士を分離する。 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.
　前述の２値化処理後に得られた画像内のｃＢＮ粒子にあたる部分（黒の部分）を粒子解析し、求めた各ｃＢＮ粒子の最大長をそれぞれ各ｃＢＮ粒子の直径とする。最大長を求める粒子解析としては、１つのｃＢＮ粒子に対してフェレ径を算出することより得られる２つの長さから大きい長さの値を最大長とし、その値を各ｃＢＮ粒子の直径とする。 　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. .
　各ｃＢＮ粒子をこの直径を有する理想球体と仮定して、計算より求めた体積を各粒子の体積として累積体積を求め、この累積体積を基に縦軸を体積百分率（％）、横軸を直径（μｍ）としてグラフを描画させ、体積百分率が５０％のときの直径をｃＢＮ粒子の平均粒径とする。これを３観察領域に対して行い、その平均値をｃＢＮ粒子の平均粒径（μｍ、この平均粒径をＤ５０という）とする。 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).
　この粒子解析を行う際には、あらかじめＳＥＭにより分かっているスケールの値を用いて、１ピクセル当たりの長さ（μｍ）を設定しておく。観察領域として、ｃＢＮ粒子が観察領域の中に少なくとも３０個以上観察される領域、すなわち、ｃＢＮ粒子の平均粒径が３μｍ程度の場合、例えば、１５μｍ×１５μｍ程度の観察領域が好ましい。 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.
＜ｃＢＮ粒子の含有量＞
　ｃＢＮ焼結体に占めるｃＢＮ粒子の含有量は、以下のとおりにして求めることができる。
　まず、最外層４であるｃＢＮ焼結体の任意の断面の組織をＳＥＭによって観察し、二次電子像を得る。得られた二次電子像内のｃＢＮ粒子に相当する部分を、ｃＢＮ粒子の平均粒径の測定方法と同様の画像処理によって抜き出す。そして、画像解析によってｃＢＮ粒子が占める面積を算出し、１画像内のｃＢＮ粒子が占める割合を求める。少なくとも３画像を処理し求めたｃＢＮ粒子の含有量の平均値を、ｃＢＮ焼結体に占めるｃＢＮ粒子の含有量（ｖｏｌ％）とする。なお、画像処理に用いる観察領域としては、ｃＢＮ粒子の平均粒径の５倍の長さの一辺をもつ正方形の領域であることが好ましい。例えば、ｃＢＮ粒子の平均粒径が３μｍである場合は、画像処理に用いる観察領域としては、１５μｍ×１５μｍ程度の領域である望ましい。 <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.
　本実施形態において、ｃＢＮ焼結体中の結合相は、Ｔｉ２ＣＮとＣｏ２Ｂを含有する。
このように、結合相中にＴｉ２ＣＮとＣｏ２Ｂを含有することにより、ｃＢＮ粒子と結合相との付着力の向上や、ｃＢＮ焼結体の靭性の向上を図ることができる。その結果、耐疲労摩耗性および耐アブレッシブ摩耗性の向上、ならびに、岩石掘削時の衝撃や振動による欠損などの損傷要因に対する耐性を向上させることができる。 In this embodiment, the binder phase in the cBN sintered body contains Ti2CN and Co2B .
Thus, by including Ti 2 CN and Co 2 B 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.
　また、本実施形態においては、最外層のＸ線回折パターンにおいて、Ｔｉ２ＣＮのピーク強度ＩＴｉ２ＣＮと、Ｃｏ２Ｂのピーク強度Ｉｃо２Ｂとの比であるＩＴｉ２ＣＮ／Ｉｃо２Ｂが０．５～２．０であることが好ましい。具体的には、最外層におけるＸ線解析（ＸＲＤ）で得られる回折パターンにおいて、回折角（２θ）が４１．９～４２．２°の位置に出現するＴｉ２ＣＮのピーク強度ＩＴｉ２ＣＮと、回折角（２θ）が４５．７～４５．９°の位置に出現するＣｏ２Ｂのピーク強度Ｉｃо２Ｂとの比であるＩＴｉ２ＣＮ／Ｉｃо２Ｂが０．５～２．０であることが好ましい。 Further, in the present embodiment, in the X-ray diffraction pattern of the outermost layer, I Ti2CN /I co2B , which is the ratio of the peak intensity I Ti2CN of Ti 2 CN to the peak intensity I co2B of Co 2 B, is 0.5 to 2.0 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 co2B , which is the ratio of the peak intensity I co2B of Co 2 B appearing at a diffraction angle (2θ) of 45.7 to 45.9°, is preferably 0.5 to 2.0. .
　結合相の成分であるＴｉ２ＣＮとＣｏ２Ｂについて、ＸＲＤにおけるそれぞれのピーク強度の比率（ＩＴｉ２ＣＮ／Ｉｃо２Ｂ）を０．５～２．０の範囲内とすることで、耐疲労摩耗性、耐アブレッシブ摩耗性に優れ、岩石掘削時の衝撃や振動による欠損などの損傷要因に対する耐性をより向上させることができる。 For Ti 2 CN and Co 2 B, which are components of the binder phase, the ratio of the respective peak intensities in XRD (I Ti2CN /I co2B ) is within the range of 0.5 to 2.0. 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.
　ここで、Ｃｏ２ＢがｃＢＮ焼結体中に生成されるメカニズムは、以下のとおりと推測する。まず、超高圧下での焼結時において、Ｔｉ２ＡｌＣあるいはＴｉ３ＡｌＣ２と、Ｃｏとが反応することでＴｉＡｌＣｏが生成され、このＴｉＡｌＣｏがｃＢＮと反応することにより、Ｃｏ２Ｂがされる。そして、このＣｏ２Ｂが生じる際にＴｉＢ２も生成されると推測する。この推測に基づけば、ＩＴｉ２ＣＮ／ＩＣｏ２Ｂが０．５未満であると、ＴｉＡｌＣｏとｃＢＮとの反応により生じるＣｏ２Ｂが焼結体中に存在する割合が多くなってしまうと考えられる。そしてこのＣｏ２Ｂは脆いため、焼結体中に存在するＣｏ２Ｂの割合が多いと、岩石掘削時に破壊の起点となり上記欠損などの損傷を招くおそれがある。一方、ＩＴｉ２ＣＮ／ＩＣｏ２Ｂが２．０より大きいと、ｃＢＮと結合相用原料が反応することで生成する焼結体中のＣｏ２Ｂが過度に少なくなり、ｃＢＮと結合相との付着力低下を招くおそれがある。さらに、焼結体中のＣｏ２Ｂが過度に少なくなると、焼結体の耐アブレッシブ摩耗性や岩石掘削時の衝撃や振動による欠損などの損傷要因に対する耐性が低下してしまうおそれもある。これらのことから、ＩＴｉ２ＣＮ／ＩＣｏ２Ｂは、０．８～１．５であることがより好ましい。なお、ピーク強度比ＩＴｉ２ＣＮ／ＩＣｏ２Ｂは、ｃＢＮ焼結体の原料の配合比を調整することで、制御することができる。 Here, the mechanism by which Co 2 B is generated in the cBN sintered body is presumed to be as follows. First, during sintering under ultrahigh pressure, TiAlCo is produced by reacting Ti2AlC or Ti3AlC2 with Co, and Co2B is produced by reacting this TiAlCo with cBN. . And it is assumed that TiB 2 is also produced when this Co 2 B is produced. Based on this assumption, it is considered that if I Ti2CN /I Co2B is less than 0.5, the ratio of Co 2 B generated by the reaction between TiAlCo and cBN in the sintered body increases. Since this Co 2 B is brittle, if the ratio of Co 2 B present in the sintered body is large, it may become the starting point of fracture during rock excavation and cause damage such as the chipping described above. On the other hand, if I Ti2CN /I Co2B is greater than 2.0, the amount of Co 2 B in the sintered body produced by the reaction between cBN and the raw material for the binder phase becomes excessively small, and the adhesion between cBN and the binder phase It may lead to a decline. Furthermore, if the amount of Co 2 B in the sintered body is excessively low, the abrasive wear resistance of the sintered body and the resistance to damage factors such as chipping due to impact and vibration during rock excavation may decrease. For these reasons, I Ti2CN /I Co2B is more preferably 0.8 to 1.5. The peak intensity ratio I Ti2CN /I Co2B can be controlled by adjusting the compounding ratio of the raw materials of the cBN sintered body.
　ここで、Ｔｉ２ＣＮのピーク強度（ＩＴｉ２ＣＮ）とＣｏ２Ｂのピーク強度（ＩＣｏ２Ｂ）は、ＣｕＫα放射線を使用して測定するＸ線解析（ＸＲＤ）により求める。具体的には、まずｃＢＮの｛１１１｝面の回折ピークを２θ＝４３．３とし、このピーク位置（角度）を基準とする。そして、２θ＝４１．９～４２．２°に出現するピークをＴｉ２ＣＮとし、２θ＝４５．７～４５．９°に出現するピークをＣｏ２Ｂとし、バックグラウンドを除去した後にピークサーチを行い、ＩＴｉ２ＣＮとＩＣｏ２Ｂをそれぞれ求める。 Here, the peak intensity of Ti 2 CN (I Ti2CN ) and the peak intensity of Co 2 B (I Co2B ) 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 = 45.7 to 45.9° is Co 2 B, and the background is removed before peak search. to obtain I Ti2CN and I Co2B , respectively.
　本実施形態において、結合相は、さらにＴｉＢ２を含有し、Ｘ線回折パターンにおいて、回折角（２θ）が４４．４～４４．６°に出現するＴｉＢ２のピーク強度ＩＴｉＢ２と、前述のＣｏ２Ｂのピーク強度Ｉｃо２Ｂとの比であるＩＣｏ２Ｂ／ＩＴｉＢ２が１．２～３．４であることが好ましい。ＩＣｏ２Ｂ／ＩＴｉＢ２が１．２未満であると、靭性の低いＴｉＢ２が過剰に焼結体中に生成されてしまい、粗大なＴｉＢ２が形成される。そしてその結果、この粗大なＴｉＢ２が岩石掘削時に破壊の起点となり、上記欠損などの損傷を招くおそれがある。一方、ＩＣｏ２Ｂ／ＩＴｉＢ２が３．４を超える場合は、Ｃｏ２Ｂに比べてＴｉＢ２が極めて少ない状態である。そのため、焼結体の原料であるＴｉ２ＡｌＣあるいはＴｉ３ＡｌＣ２とＣｏとが最初に反応することで生成されたＴｉＡｌＣｏがｃＢＮと反応して生成されたＣｏ２Ｂではなく、Ｃｏが直接ｃＢＮと反応して生成されたＣｏ２Ｂが多い焼結体となってしまう。その結果、ｃＢＮと結合相との付着力低下を招くおそれがある。さらに、Ｃｏ２Ｂに比べてＴｉＢ２が極めて少ない状態となると、ｃＢＮ焼結体の耐アブレッシブ摩耗性や岩石掘削時の衝撃や振動による欠損などの損傷要因に対する耐性が低下するおそれもある。これらのことから、ＩＣｏ２Ｂ／ＩＴｉＢ２は、１．５～２．５であることがより好ましく、１．６～２．０であることがさらにより好ましい。
なお、ピーク強度比ＩＣｏ２Ｂ／ＩＴｉＢ２は、ｃＢＮ焼結体の原料の配合比を調整することで、制御することができる。 In this embodiment, the binder phase further contains TiB 2 , and in the X-ray diffraction pattern, the peak intensity I TiB2 of TiB 2 appearing at a diffraction angle (2θ) of 44.4 to 44.6°, and the above-mentioned I Co2B /I TiB2 , which is the ratio of the peak intensity I co2B of Co 2 B, is preferably 1.2 to 3.4. When I Co2B /I TiB2 is less than 1.2, TiB 2 with low toughness is excessively generated in the sintered body, and coarse TiB 2 is formed. As a result, this coarse TiB 2 may become a starting point of fracture during rock excavation, and may cause damage such as the chipping described above. On the other hand, when I Co2B /I TiB2 exceeds 3.4, TiB 2 is extremely less than Co 2 B. Therefore, Co is directly cBN rather than TiAlCo generated by the first reaction between Co and TiAlC or TiAlC2 , which is the raw material of the sintered body, and TiAlCo is not Co2B generated by reacting with cBN. A sintered body with a large amount of Co 2 B generated by reaction with is obtained. As a result, there is a risk that the adhesion between cBN and the binder phase will be reduced. Furthermore, when TiB 2 is extremely less than Co 2 B, the abrasive wear resistance of the cBN sintered body and the resistance to damage factors such as chipping due to impact and vibration during rock excavation may decrease. For these reasons, I Co2B /I TiB2 is more preferably 1.5 to 2.5, and even more preferably 1.6 to 2.0.
The peak intensity ratio I Co2B /I TiB2 can be controlled by adjusting the compounding ratio of the raw materials of the cBN sintered body.
　以上、本実施形態の硬質層３における結合相について説明してきたが、結合相は、上記ＴｉＢ２の他に、ＡｌＮ、Ａｌ２Ｏ３のうち１種または２種以上が含まれることが好ましい。さらに、本実施形態の硬質層３は、上述してきた組成に加え、本発明の効果を損なわない範囲で、不可避的な不純物として他の合金が含まれていてもよい。 Although the binder phase in the hard layer 3 of the present embodiment has been described above, the binder phase preferably contains one or more of AlN and Al 2 O 3 in addition to TiB 2 . 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.
　また、以上説明してきた結合相の組織（組成）は、上述したＸ線解析（ＸＲＤ）により得られる回折パターンによって同定することができる。 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).
　図２に、本実施形態の掘削チップの変形例を示す。図２に示すように、本実施形態の硬質層３は、最外層４とチップ本体２との間に、中間層５を備えてもよい。すなわち、最外層４とチップ本体２との間には、少なくとも１層の中間層５が設けられてもよい。これにより、最外層４の剥離を防止できる。すなわち、上述のｃＢＮ焼結体からなる最外層４をチップ本体２に直接形成した場合、超硬合金等の硬質材料からなるチップ本体２と最外層４との収縮率の違いにより、焼結後に応力が残留し、最外層４の厚みによっては、チップ本体２と最外層４との界面にクラックが生じるおそれがある。図２に示す変形例では、最外層４とチップ本体２との間に中間層５を設けているので、中間層５が応力緩和層として機能する。その結果、クラックの発生を抑制でき、最外層４の剥離を防止できる。 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-described 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.
　中間層５の構成は、硬質相（ダイヤモンド、ｃＢＮあるいはその両方など）の含有量が最外層４より小さく、またその硬さ（ビッカース硬さ）がチップ本体２より大きいこと以外は特に限定されない。例えば、中間層５はＴｉの炭窒化物や硼化物を主とするセラミックス結合相のｃＢＮ焼結体やＡｌと、Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅのうち少なくとも１種とを含む触媒金属および炭化タングステンにより焼結したｃＢＮ焼結体であってもよい。また、上記金属触媒に、Ｗ、Ｍｏ、Ｃｒ、Ｖ、Ｚｒ、Ｈｆのうち少なくとも１種を含む金属添加物が添加されていてもよい。さらに、中間層５をダイヤモンド、コバルト、および炭化タングステンなどからなる多結晶ダイヤモンド焼結体で構成することもできる。 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. Furthermore, the intermediate layer 5 can also be composed of a polycrystalline diamond sintered body made of diamond, cobalt, tungsten carbide, or the like.
　ここで、中間層５は、１０．０～７０．０ｖｏｌ％のｃＢＮ粒子またはダイヤモンド粒子を含有していることが好ましい。硬質粒子であるｃＢＮ粒子またはダイヤモンド粒子の含有量が１０．０ｖｏｌ％未満の場合は、中間層５は応力緩和層として機能するが耐衝撃性が低く、破損の起点となる可能性が高い。また、ｃＢＮ粒子またはダイヤモンド粒子の含有量が７０．０ｖｏｌ％を超える場合は、チップ本体２と中間層５との収縮率の差が大きくなり、その結果、掘削チップを工具として使用する際、加わる衝撃によってチップ本体２と中間層５との界面付近に工具破損の起点となるクラックが生じやすくなる。そのため、中間層５を応力緩和層として十分に機能させるためには、中間層５におけるｃＢＮ粒子またはダイヤモンド粒子の含有量を１０．０～７０．０ｖｏｌ％とすることが好ましい。より好ましくは、３０～６０ｖｏｌ％である。 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 to 60 vol%.
　なお、図２に示す例では、中間層５が単層構造（１層構造）とされているが、本実施形態はこれに限らない。すなわち、本実施形態では、中間層５が２層以上の多層構造でもよい。ただし、中間層５を３層以上の多層構造とする場合には、最外層４側からチップ本体２側に向かうに従い、ビッカース硬さが小さくなるよう、硬度に傾斜を付与することが望ましい。すなわち、中間層５を多層構造とする場合には、最外層４側からチップ本体２側に向かうに従い、中間層５のｃＢＮ粒子またはダイヤモンド粒子の含有量が漸減するよう調整することが望ましい。 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.
　中心線Ｃ上における最外層４の厚さは、０．３ｍｍ以上４．０ｍｍ以下とすることが好ましい。最外層４の厚さが０．３ｍｍ未満の場合、掘削チップがすぐに摩滅して短寿命となるおそれがある。一方、最外層４の厚さが４．０ｍｍ超の場合、焼結時の残留応力によるクラックが発生しやすくなり、掘削時の突発欠損を招くおそれがある。最外層４の厚さは、より好ましくは０．４ｍｍ以上２．５ｍｍ以下である。 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.
　また、中心線Ｃ上における中間層５全体の厚さは、０．２ｍｍ以上１．０ｍｍ以下とすることが好ましい。中間層５の厚さが０．２ｍｍ未満の場合、均一な層が形成され難いため、焼結時の残留応力が吸収され難くなる。その結果、チップの応力緩和の役割が果たせなくなるおそれがある。一方、中間層５の厚さが１．０ｍｍを超える場合、硬質層３（最外層４および中間層５）全体の厚さが大きくなり、焼結時の残留応力によるクラックが発生しやすくなる。さらにその結果、掘削時の突発欠損を招くおそれがある。よって、中間層５全体の厚さはより好ましくは０．３ｍｍ以上０．８ｍｍ以下である。 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 becomes difficult to absorb 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.
　次に、本実施形態の掘削チップの好適な製造方法を説明する。
　本実施形態の掘削チップの好適な製造方法は、最外層４における結合相の原料粉末と、ｃＢＮ粒子とを混合した混合粉末を得る工程と、混合粉末に熱処理を行う工程と、その熱処理後の混合粉末と中間層５の原料粉末とチップ本体２とを焼結する工程とを備える。 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 .
　まず、最外層４における結合相の原料粉末とｃＢＮ粒子とを、所定の組成となるように混合し、混合粉末を得る。最外層４の結合相の原料粉末として、例えば、１μｍ～５００μｍの範囲のＴｉ２ＡｌＣ粉末、Ｔｉ３ＡｌＣ２粉末、Ｃｏ粉末、ＴｉＮ粉末、ＴｉＣ粉末、ＴｉＣＮ粉末、および、ＴｉＡｌ３粉末を用いることができる。 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, Co powder, TiN powder, TiC powder, TiCN powder, and TiAl 3 powder with a range of 1 μm to 500 μm are used. can be done.
　次に、得られた混合粉末に対し、真空炉を用いて、例えば、２５０℃以上９００℃以下にて熱処理を行う。これにより、粗粒なＴｉ２ＡｌＣあるいはＴｉ３ＡｌＣ２をＴｉＯ２とＡｌ２Ｏ３に分解させることなく原料表面の吸着水を低減させることができ、超高圧高温焼結時のＣｏの酸化を低減できる。さらには、Ｔｉ２ＡｌＣあるいはＴｉ３ＡｌＣ２とＣｏとを最初に反応させることができる。 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 , and oxidation of Co during ultrahigh pressure and high temperature sintering can be suppressed. can be reduced. Furthermore, Ti 2 AlC or Ti 3 AlC 2 and Co can be reacted first.
　ここで、原料粉末として粗粒なＴｉ２ＡｌＣあるいはＴｉ３ＡｌＣ２を用いることにより、焼結時の酸素との反応が粒の内部まで進行することを抑制し、焼結後の焼結体内にＴｉ２ＣＮを生成させることができる。原料であるＣｏは、まず、Ｔｉ２ＡｌＣあるいはＴｉ３ＡｌＣ２と反応してＴｉＡｌＣｏが生成され、さらに、このＴｉＡｌＣｏがｃＢＮと反応することにより、Ｃｏ２ＢとＴｉＢ２とＡｌＮが生成される。これにより、ｃＢＮと結合相との結合強度を高めることができる。さらに、結合相成分を粗粒としたことによる靭性の低下を、焼結体中に分散して生成された細かなＣｏ２Ｂによる靭性向上効果により補うことができる。これらの結果、岩石掘削時の耐摩耗性と耐アブレッシブ摩耗性に優れ、岩石掘削時の衝撃や振動による欠損などの損傷要因に対する耐性の高い掘削チップを得ることができる。 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 can be produced. The raw material Co first reacts with Ti 2 AlC or Ti 3 AlC 2 to produce TiAlCo, which then reacts with cBN to produce Co 2 B, TiB 2 and AlN. This can increase the bond strength between the cBN and the binder phase. Furthermore, the decrease in toughness due to coarse grains in the binder phase component can be compensated for by the effect of improving toughness due to fine Co 2 B dispersed and generated in the sintered body. 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.
　次に、上記熱処理後の混合粉末と中間層５の原料粉末とチップ本体２とを、通常の超高圧焼結装置に装入し、例えば、５ＧＰａ以上の圧力、かつ、１６００℃以上の温度の超高圧高温条件下で所定時間、焼結する。このように、最外層４、中間層５およびチップ本体２を一体に焼結することにより、本実施形態の掘削チップを製造することができる。また、結合相にＴｉ２ＣＮとＣｏ２Ｂを含むようなｃＢＮ焼結体を作製することにより、衝撃による疲労摩耗、破砕した岩石が堀削工具の周囲を取り巻く中で岩石の硬質成分が工具刃先と岩石の間に入り込み生じる微小な切削作用によるアブレッシブ摩耗、さらには、岩石を破壊するための衝撃や振動による欠損などの損傷要因、それぞれに対する耐性の高い本実施形態に係る硬質層３を得ることができる。 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 Co 2 B in the binder phase, fatigue wear due to impact and crushed rock surrounding the excavating tool can cause the hard components of the rock to affect the tool. To obtain the hard layer 3 according to the present embodiment, which is highly resistant to abrasive wear due to minute cutting action generated between the cutting edge and the rock, and damage factors such as chipping due to impact or vibration for breaking the rock. be able to.
　次に、以上説明したような、本実施形態に係る掘削チップ１が先端部に取り付けられる掘削ビット（掘削工具）について説明する。
　本実施形態に係る掘削ビットは、図３に示すように、軸線Ｏを中心とした、概略有底円筒状をなすビット本体１１を有する。本実施形態においては、ビット本体１１の有底部が先端部（図３において上側部分）とされており、この先端部に掘削チップ１が取り付けられる。ビット本体１１は、例えば、鋼材等により形成される。また、ビット本体１１において、円筒状の後端部（図２において下側部分）の内周には雌ネジ部１２が形成されている。掘削装置に連結された掘削ロッドがこの雌ネジ部１２にねじ込まれ、軸線Ｏ方向の先端側に向けての打撃力と推力および軸線Ｏ回りの回転力が伝達されることにより、掘削チップ１によって岩盤を破砕して掘削孔を形成する。 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.
　ビット本体１１の先端部は後端部よりも僅かに外径が大径とされている。また、この先端部の外周には、軸線Ｏに平行に延びる排出溝１３が周方向に間隔をあけて複数条形成されており、掘削チップ１により岩盤が破砕されて生成された破砕屑がこの排出溝１３を通して後端側に排出される。
　また、有底である雌ネジ部１２底面からは、軸線Ｏに沿ってブロー孔１４が形成されている。このブロー孔１４は、ビット本体１１の先端部において、軸線Ｏに対して斜めに分岐し、ビット本体１１の先端面にて開口している。このような構成によって、上記掘削ロッドを介して供給される圧縮空気のような流体を噴出して破砕屑の排出を促進する。 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.
　さらに、ビット本体１１の先端面は、内周側の軸線Ｏに垂直な軸線Ｏを中心とした円形のフェイス面１５と、このフェイス面１５の外周に位置し、外周側に向かうに従いビット本体１１の後端側に向かう円錐台面状のゲージ面１６とを備えている。ブロー孔１４はフェイス面１５に開口するとともに、排出溝１３の先端はゲージ面１６の外周側に開口している。また、これらフェイス面１５とゲージ面１６には、それぞれブロー孔１４と排出溝１３の開口部を避けるようにして、断面円形の複数の取付孔１７がフェイス面１５とゲージ面１６に対して垂直に形成されている。 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
　本実施形態の掘削チップ１は、図３に示すように、この取付孔１７に埋設されて取り付けられる。具体的には、取付孔１７に、チップ本体２の後端部２Ａが埋没させられた状態で、圧入や焼き嵌め等によって締まり嵌めされたり、ロウ付けされたりすることにより、掘削チップ１が固定される。そして、硬質層３が被覆された掘削チップ１の先端部がフェイス面１５およびゲージ面１６から突出して、上述した打撃力と推力および回転力により岩盤を破砕する。 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.
　なお、図３に示すように、掘削チップ１は、掘削ビットの軸線Ｏに対して傾斜して固定される場合があるため、掘削チップ１の中心線Ｃの軸方向は、掘削ビットの軸線Ｏの軸方向とは、必ずしも一致しない。 As shown in FIG. 3, since the drilling tip 1 may be fixed at an angle with respect to the axis O of the drilling bit, the axial direction of the centerline C of the drilling tip 1 coincides with the axis O of the drilling bit. does not necessarily match the axial direction of .
　以上、本発明の実施形態の掘削チップおよび掘削ビット（掘削工具）ついて説明したが、本発明はこれに限定されることはなく、その発明の技術的思想を逸脱しない範囲で適宜変更可能である。すなわち、本発明の各実施形態における各構成およびそれらの組み合わせ等は一例であり、本発明の趣旨から逸脱しない範囲内で、構成の付加、省略、置換およびその他の変更が可能である。また、本発明は実施形態によって限定されることはない。 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.
　次に、本発明の掘削チップおよび掘削ビットの実施例を挙げて、本発明の効果について実証する。 Next, examples of the drilling tip and drilling bit of the present invention will be given to demonstrate the effects of the present invention.
　（実施例１）
　まず、実施例１として、ｃＢＮ焼結体を最外層に適用した掘削チップの実施例を挙げて、本発明の効果について実証する。 (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）最外層
（１－１）最外層の原料粉末の準備
　最外層の硬質原料として、平均粒径が０．５～３５μｍの範囲内であるｃＢＮ粉末（ｃＢＮ原料）を用意した。また、結合相を構成する原料粉末として、Ｔｉ２ＡｌＣ粉末あるいはＴｉ３ＡｌＣ２粉末と、Ｃｏ原料とをそれぞれ用意した。Ｔｉ２ＡｌＣ粉末およびＴｉ３ＡｌＣ２粉末の平均粒径はいずれも５０μｍであった。Ｃｏ原料の平均粒径は１μｍであった。また、結合相の原料粉末として、さらに、ＴｉＮ粉末、ＴｉＣ粉末、ＴｉＣＮ粉末、ＴｉＡｌ３粉末を別途準備した。これらＴｉＮ粉末、ＴｉＣ粉末、ＴｉＣＮ粉末、ＴｉＡｌ３粉末の平均粒径は、０．３μｍ～０．９μｍであった。結合相の原料の配合組成を表１に示す。 (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. As raw material powders constituting the binder phase, Ti 2 AlC powder or Ti 3 AlC 2 powder and Co raw material were prepared. Both the Ti 2 AlC powder and the Ti 3 AlC 2 powder had an average particle size of 50 μm. The Co raw material had an average particle size of 1 μm. In addition, TiN powder, TiC powder, TiCN powder, and TiAl3 powder were separately prepared as raw material powders of the binder phase. The average particle size of these TiN powder, TiC powder, TiCN powder and TiAl 3 powder was 0.3 μm to 0.9 μm. Table 1 shows the composition of the raw materials of the binder phase.
（１－２）混合
　これら最外層の原料粉末を、超硬合金で内張りされた容器内に、超硬合金製のボールとアセトンと共に充填し、蓋をした後にボールミルにより混合した。混合時間は、原料粉末を細かく粉砕させないように、１時間とした。なお、本実施例では採用していないが、原料粉末の混合工程では、超音波攪拌装置を用いて原料粉末の凝集を解砕しながら混合することがより好ましい。 (1-2) Mixing These raw material powders for the outermost layer were placed in a container lined with cemented carbide together with balls made of cemented carbide and acetone, covered, and then 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.
（２）中間層
　また、平均粒径が６μｍのｃＢＮ粉末（硬質粒子）と、平均粒径が４μｍのＷ粉末と、平均粒径が０．９μｍのＡｌ粉末と、平均粒径が３μｍのＣｏ粉末とを、これらの合量を１００ｖｏｌ％としたときのｃＢＮ粒子の含有量が表２の割合となるように配合し、湿式混合し、乾燥した。これにより、本発明例の中間層（種別Ｉ）の原料粉末を得た。
　また、平均粒径が１０μｍと平均粒径が２μｍのダイヤモンド粒子（硬質粒子）と、平均粒径が４μｍのＷ粉末と、平均粒径が２．１μｍのＷＣ粉末とを、これらの合量を１００ｖｏｌ％としたときのダイヤモンド粒子の含有量が表２の割合となるように配合し、湿式混合し、乾燥した。これにより、本発明例の中間層（種別ＩＩＩ）の原料粉末を得た。
　また、平均粒径が６μｍのｃＢＮ粉末（硬質粒子）と、平均粒径が５０μｍのＴｉ３ＡｌＣ２粉末と、平均粒径が３μｍのＣｏ粉末とを、これらの合量を１００ｖｏｌ％としたときのｃＢＮ粒子の含有量が表２の割合となるように配合し、湿式混合し、乾燥した。これにより、本発明例の中間層（種別ＩＩ）の原料粉末を得た。 (2) Intermediate layer In addition, cBN powder (hard particles) with an average particle size of 6 μm, W powder with an average particle size of 4 μm, Al powder with an average particle size of 0.9 μm, and Co powder with an average particle size of 3 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, W powder with an average particle size of 4 μm, and WC powder with an average particle size of 2.1 μm are added together. They were mixed so that the content of diamond particles at 100 vol % would be 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, when the total amount of cBN powder (hard particles) with an average particle size of 6 μm, Ti 3 AlC 2 powder with an average particle size of 50 μm, and Co powder with an average particle size of 3 μm is 100 vol% The content of cBN particles was blended so as to have the ratio 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.
（３）仮熱処理
　上記工程によって得られた最外層の原料粉末と中間層の原料粉末とを、仮熱処理し、粉末表面から吸着水を蒸発させた。
　仮熱処理は、圧力が１Ｐａ以下の真空雰囲気中で、表３に記載の「混合後の熱処理温度」にて行った。その理由は、次のとおりである。
　仮熱処理における熱処理温度が２５０℃未満であると、吸着水が十分に原料表面から解離せず、超高圧高温焼結時にＣｏが酸化し、Ｔｉ２ＡｌＣあるいはＴｉ３ＡｌＣ２の反応を阻害するおそれがある。さらに、Ｔｉ２ＡｌＣあるいはＴｉ３ＡｌＣ２が超高圧高温焼結中に、原料に吸着していた水分と反応してＴｉＯ２とＡｌ２Ｏ３に分解されてしまい、その結果、超高圧高温焼結後の焼結体の結合相中にＴｉ２ＡｌＣの存在が少なくなり、焼結体の靭性が低下してしまう。一方、仮熱処理における熱処理温度が９００℃より高い温度であると、仮熱処理の段階でＴｉ２ＡｌＣあるいはＴｉ３ＡｌＣ２が吸着水の酸素と反応し、ＴｉＯ２とＡｌ２Ｏ３に分解してしまい、超高圧焼結時におけるＴｉＡｌＣｏを生成させるためのＣｏと反応するＴｉ２ＡｌＣあるいはＴｉ３ＡｌＣ２がなくなってしまう。そうすると、結果としてｃＢＮとの反応が十分にできず、ｃＢＮと結合相との付着力が低下し、焼結体の耐アブレッシブ摩耗性や岩石掘削時の衝撃や振動による欠損などの損傷要因に対する耐性が低下してしまう。よって、仮熱処理における熱処理温度は、２５０～９００℃が好ましい。 (3) Temporary Heat Treatment The raw material powder for the outermost layer and the raw material powder for the intermediate layer obtained by the above steps were subjected to temporary heat treatment to evaporate the adsorbed water from the powder surfaces.
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 will not be sufficiently dissociated from the raw material surface, and Co will be oxidized during ultra-high pressure and high temperature sintering, which may hinder the reaction of Ti 2 AlC or Ti 3 AlC 2 . There is Furthermore, Ti 2 AlC or Ti 3 AlC 2 reacts with the moisture adsorbed to the raw material during the ultra-high pressure and high temperature sintering, and is decomposed into TiO 2 and Al 2 O 3 . The presence of Ti 2 AlC in the binder phase of the sintered body after bonding is reduced, and the toughness of the sintered body is lowered. 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 . As a result, there is no Ti 2 AlC or Ti 3 AlC 2 that reacts with Co to generate TiAlCo during ultra-high pressure sintering. As a result, the reaction with cBN cannot be sufficiently performed, the adhesion between the cBN and the binder phase is reduced, and the abrasive wear resistance of the sintered body and resistance to damage factors such as fracture due to impact and vibration during rock excavation decreases. Therefore, the heat treatment temperature in the preliminary heat treatment is preferably 250 to 900.degree.
（４）焼結
　次いで、仮熱処理後の最外層の原料粉末と中間層の原料粉末を、ＷＣ：９４ｗｔ％、Ｃｏ：６ｗｔ％の超硬合金よりなる基体（チップ本体）とともに、焼結圧力：６．０ＧＰａ、焼結温度：１６００℃、焼結時間：２０分の条件下で一体に焼結した。これにより、半径（２／Ｄ）４．５ｍｍ、チップの中心線方向の長さ１６ｍｍの、本発明例に係る掘削チップ（本発明例チップ）１～１２を製造した。なお、チップ本体先端部は半径５．７５ｍｍのラウンド形状であった。また、チップの中心線方向における最外層および中間層を表３の層厚とした。 (4) Sintering Next, the raw material powder for the outermost layer and the raw material powder for the intermediate layer after the temporary heat treatment are sintered together with a base (tip body) made of a cemented carbide containing 94 wt% WC and 6 wt% Co, under a sintering pressure of: It was integrally sintered under the conditions of 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 leading end of the tip body had a round shape 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.
　また、比較のために、表３に示す比較例１～５に係る掘削チップを製造した。比較例１～５の掘削チップを製造するにあたり、硬質原料として、平均粒径が１．０～４．０μｍのｃＢＮ原料を用意した。また、結合相を構成する原料粉末として、表１に示すように、ＴｉＣ、ＴｉＣＮなどを含む原料粉末を用意した。これらを表１に示す組成となるように配合し、上述した本発明例と同様の条件でボールミルにより混合を行った。なお、比較例で用いた中間層用原料は、本発明例で用いた原料と同じとした。 Also, for comparison, drilling tips according to Comparative Examples 1 to 5 shown in Table 3 were manufactured. In producing the drilling tips of Comparative Examples 1 to 5, 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.
　その後、原料粉末は温度６００℃～９００℃の範囲内の所定の温度で仮熱処理（表３では、「混合後の熱処理温度」と記載している）し、その後、ＷＣ：９４ｗｔ％、Ｃｏ：６ｗｔ％の超硬合金よりなる基体とともに、超高圧焼結装置に装入して、焼結圧力：５．０ＧＰａ、焼結温度：１６００℃、焼結時間：２０分の条件下で一体に焼結した。これにより、表３に示す比較例の掘削チップ（比較例チップ）１～５を製造した。なお、各比較例の掘削チップの寸法は、本発明例と同様とした。 After that, the raw material powder is subjected to preliminary heat treatment at a predetermined temperature in the range of 600° C. to 900° C. (in Table 3, it is described as “heat treatment temperature after mixing”), and then WC: 94 wt%, Co: Together with a substrate made of 6 wt% cemented carbide, it is charged into an ultra-high pressure sintering apparatus and integrally sintered under the conditions of sintering pressure: 5.0 GPa, sintering temperature: 1600 ° C., sintering time: 20 minutes. tied. Thus, comparative drilling tips (comparative example tips) 1 to 5 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.
　以上によって得られた、本発明例および比較例の掘削チップの詳細は表３に示す通りである。なお、表３に示す、最外層におけるｃＢＮ粒子の含有割合および平均粒径、ピーク強度比ＩＴｉ２ＣＮ／ＩＣｏ２Ｂ、ピーク強度比ＩＣｏ２Ｂ／ＩＴｉＢ２については、上記の同様の方法によって測定、算出した。 Table 3 shows the details of the drilling tips of the present invention examples and comparative examples obtained as described above. The content ratio and average particle diameter of the cBN particles in the outermost layer, the peak intensity ratio I Ti2CN /I Co2B , and the peak intensity ratio I Co2B /I TiB2 shown in Table 3 were measured and calculated by the same methods as described above. .
　ここで、図４に、本実施例における本発明例９のＸ線回折パターンを示す。図４に示すとおり、２θ＝４１．９～４２．２°にＴｉ２ＣＮのピークが、２θ＝４５．７～４５．９°にＣｏ２Ｂのピークがそれぞれ確認できる。 Here, FIG. 4 shows the X-ray diffraction pattern of Inventive Example 9 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 Co 2 B peak can be confirmed at 2θ=45.7 to 45.9°.
　次に、得られた本発明例および比較例の各掘削チップをＮＣ旋盤に取り付け、以下の条件にて湿式切削試験を行い、評価した。 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.
＜湿式切削試験の条件＞
　切削速度：１５０ｍ／ｍｉｎ
　切込量：０．３ｍｍ
　送り量：０．１ｍｍ／ｒｅｖ
　被削材：花崗岩（滝根産）、形状Φ１５０ｍｍ×２００ｍｍＬ <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
＜評価方法＞
　切削長（切削距離）が７５０ｍのときの刃先の摩耗量と刃先の状態を確認した。ただし、切削長が７５ｍ毎に刃先を観察し、欠損の有無、摩耗量を測定した。摩耗量が２．３ｍｍ（２３００μｍ）を超えていればその時点で切削試験を中止した。なお、摩耗量は以下の方法で算出した。
　切削試験後の試料には円形の摩耗痕が生じる。この円形摩耗痕を、画像解析ソフト「ＩｍａｇｅＪ（米国国立衛生研究所公開）」を用いて円近似し、このときの長軸を摩耗量として算出した。結果を表４に示す。 <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.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表４から明らかなように、本発明例の掘削チップは、いずれも摩耗量が少ないことから、耐アブレッシブ摩耗性に優れ、さらに掘削工具として用いても、岩石を破壊するための衝撃や振動による欠損などの損傷要因に対する耐性を有する。一方、比較例の掘削チップはいずれも、わずかな切削長さで、欠損が発生するか、または高い摩耗量を示した。したがって、比較例の掘削チップはいずれも、耐アブレッシブ摩耗性能は低く、欠損しやすいため、掘削工具として用いることが困難である。 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.
（実施例２）
　表３に示す本発明例および比較例の掘削チップの中から本発明例（本発明チップ）１，６，７および比較例（比較例チップ）２，４，５を各々７つ準備した。そして、図３に示したようなビット径４５ｍｍのビット本体におけるフェイス面に２つ、ゲージ面に５つの、合わせて７つ取り付けた６種の掘削ビット（本発明ビット１～３、比較例ビット１～３）を製造した。 (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, 6 and 7 and comparative examples (comparative example tips) 2, 4 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.
　次に、これらの掘削ビットにより、１つの掘削長が４ｍの掘削孔を複数掘削する掘削作業を行い、掘削チップが寿命に至るまでのトータル掘削長（ｍ）を測定した。加えて、掘削チップが寿命に達したときのチップ破損状態を確認した。結果を表５に示す。
　なお、掘削チップ（ボタンチップ）がチッピング等の欠損を生じることなく最外層が徐々に摩耗した場合は正常摩耗と判断した。これらの摩耗領域（摩耗量）が大きくなり、最終的にゲージ径がビット本体の外径と等しくなったときにビットが寿命に達したと判断した。一方、チップ本体が２つ以上欠損し、その影響で掘削速度が低下したときもビットが寿命に達したと判断した。なお、掘削条件は以下のとおりとした。 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.
＜掘削条件＞
　掘削装置：ＴＡＭＲＯＣＫ社製型番Ｈ２０５Ｄ
　打撃圧力：１６０ｂａｒ
　フィード（送り）圧力：８０ｂａｒ
　回転圧力：５５ｂａｒ
　ブロー孔からは水（水圧：１８ｂａｒ）を供給した。 <Drilling conditions>
Drilling equipment: model number H205D manufactured by TAMROCK
Impact pressure: 160bar
Feed pressure: 80 bar
Rotation pressure: 55bar
Water (water pressure: 18 bar) was supplied from the blow hole.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　表５に示すとおり、比較例（比較例チップ）２，４，５を取り付けた比較例ビット１～３はいずれも、寿命までの掘削長が１００ｍに及ばず、欠損により掘削チップは寿命に達した。これに対して、発明例（比較例チップ）１，６，７を取り付けた本発明ビット１～３はいずれも、１００ｍ以上の掘削が可能であった。 As shown in Table 5, the excavation length of bits 1 to 3 attached with comparative examples (comparative tips) 2, 4, and 5 did not exceed 100 m until the end of their life, and the digging tips reached the end of their life due to chipping. did. On the other hand, the invention bits 1 to 3 to which the invention examples (comparative tips) 1, 6 and 7 were attached were all capable of excavating 100 m or more.
　本発明によれば、耐疲労摩耗性、耐アブレッシブ摩耗性に優れ、さらに、岩石を破壊するための衝撃や振動による欠損などの損傷要因に対する耐性を有する掘削チップを提供するとともに、このような掘削チップを取り付けた掘削工具を提供することができる。 According to the present invention, there is provided a drilling tip that is excellent in fatigue wear resistance and abrasive wear resistance, and has resistance to damage factors such as chipping due to impact and vibration for breaking rocks, and provides such a drilling tip. A drilling tool can be provided with an attached tip.
　１　　掘削チップ
　２　　チップ本体
　２Ａ　　チップ本体２の後端部
　２Ｂ　　チップ本体２の先端部
　２ａ　　凸部
　２ｂ　　凹部
　３　　硬質層
　４　　最外層
　５　　中間層
　１１　ビット本体
　Ｃ　　中心線
　Ｏ　　ビット本体１１の軸線
　Ｄ　　チップ本体２の後端部２Ａの直径
　ｒ１　　中心線Ｃに沿った断面において凸部２ａがなす凸円弧の半径
　ｒ２　　中心線Ｃに沿った断面において凹部２ｂがなす凹円弧の半径
　Ｐ　　中心線Ｃに沿った断面における凸部２ａと凹部２ｂとの接点
　Ｑ　　中心線Ｃに沿った断面における凸部２ａがなす凸円弧の中心
　Ｌ　　接点Ｐと中心Ｑとを結ぶ直線
　θ　　中心線Ｃに沿った断面において直線Ｌが中心線Ｃに対してなす角度 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 (7)

  1. 　掘削ビットの先端部に取り付けられるように構成された掘削チップであって、
    　前記掘削チップの中心線を中心とした円柱形状または円板形状をなす後端部と、前記後端部から前記掘削チップの先端側に向かうに従い前記中心線からの半径が漸次小さくなる先端部とを有するチップ本体と、
    　前記チップ本体の前記先端部を被覆する硬質層と、
    を備え、
    　前記硬質層は、立方晶窒化ホウ素粒子と結合相とを有するｃＢＮ焼結体からなる最外層を有し、
    　前記結合相は、Ｔｉ２ＣＮとＣｏ２Ｂを含有することを特徴とする掘削チップ。     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 having a radius from the center line that gradually decreases from the rear end portion toward the front end side of the drilling tip. 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 Co2B .
  2. 　前記最外層のＸ線回折パターンにおいて、回折角（２θ）が４１．９～４２．２°の位置に出現するＴｉ２ＣＮのピーク強度ＩＴｉ２ＣＮと、回折角（２θ）が４５．７～４５．９°の位置に出現するＣｏ２Ｂのピーク強度Ｉｃо２Ｂとの比であるＩＴｉ２ＣＮ／Ｉｃо２Ｂが０．５～２．０であることを特徴とする請求項１に記載の掘削チップ。 In the X - ray diffraction pattern of the outermost layer, the peak intensity ITi CN of Ti CN appearing at a diffraction angle ( 2θ) of 41.9 to 42.2° and the diffraction angle (2θ) of 45.7 to 45.7 2. The drilling tip according to claim 1, wherein ITi 2 CN/Ico2B, which is a ratio of the peak intensity Ico2B of Co 2 B appearing at a position of 45.9°, is 0.5 to 2.0.
  3. 　前記結合相は、ＴｉＢ２を含有し、
    　前記最外層のＸ線回折パターンにおいて、回折角（２θ）が４４．４～４４．６°に出現するＴｉＢ２のピーク強度ＩＴｉＢ２と、回折角（２θ）が４５．７～４５．９°の位置に出現するＣｏ２Ｂのピーク強度Ｉｃо２Ｂとの比であるＩＣｏ２Ｂ／ＩＴｉＢ２が１．２～３．４であることを特徴とする請求項１または２に記載の掘削チップ。     The binder phase contains TiB2,
    In the X-ray diffraction pattern of the outermost layer, the peak intensity ITiB2 of TiB2 appearing at a diffraction angle (2θ) of 44.4 to 44.6° and the position at a diffraction angle (2θ) of 45.7 to 45.9° 3. The drilling tip according to claim 1 or 2, wherein ICo 2 B/ITiB2, which is the ratio of the peak intensity Ico2B of Co 2 B appearing at the bottom, is 1.2 to 3.4.
  4. 　前記硬質層は、前記最外層と前記チップ本体との間に、中間層を備え、
    　前記中間層が、１０．０～７０．０ｖｏｌ％の立方晶窒化ホウ素粒子またはダイヤモンド粒子を含有することを特徴とする請求項１～３の何れか一項に記載の掘削チップ。     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 3, characterized in that said intermediate layer contains 10.0 to 70.0 vol% of cubic boron nitride particles or diamond particles.
  5. 　前記最外層における、前記立方晶窒化ホウ素粒子の体積率は、７０．０～９５．０ｖоｌ％であることを特徴とする請求項１～４の何れか一項に記載の掘削チップ。 The drilling tip according to any one of claims 1 to 4, wherein the volume fraction of the cubic boron nitride particles in the outermost layer is 70.0 to 95.0 vol%.
  6. 　前記最外層における、前記立方晶窒化ホウ素粒子の平均粒径は、０．５～３０．０μｍであることを特徴とする請求項１～５の何れか一項に記載の掘削チップ。 The drilling tip according to any one of claims 1 to 5, wherein the cubic boron nitride particles in the outermost layer have an average particle size of 0.5 to 30.0 µm.
  7. 　請求項１～６の何れか一項に記載の掘削チップと、
    　先端面において前記掘削チップを保持し、軸線回りに回転させられる工具本体と、を備えることを特徴とする掘削工具。     A drilling tip according to any one of claims 1 to 6;
    A drilling tool, comprising: a tool body that holds the drilling tip on a tip surface thereof and is rotatable about an axis.
PCT/JP2022/015657 2021-03-31 2022-03-29 Drilling tip and drilling tool WO2022210771A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008517868A (en) * 2004-10-29 2008-05-29 エレメント シックス （プロダクション）（プロプライエタリィ） リミテッド Cubic boron nitride compact
WO2010119962A1 (en) * 2009-04-17 2010-10-21 株式会社タンガロイ Cubic boron nitride sintered compact and coated cubic boron nitride sintered compact
JP2015523954A (en) * 2012-05-31 2015-08-20 ダイヤモンド イノベイションズ インコーポレーテッド Sintered super-hard compact for cutting tools and its manufacturing method
JP2019065513A (en) * 2017-09-29 2019-04-25 三菱マテリアル株式会社 Drilling chip, drilling tool, and production method of drilling chip
JP6798648B1 (en) * 2019-12-16 2020-12-09 住友電気工業株式会社 Cubic boron nitride sintered body

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008517868A (en) * 2004-10-29 2008-05-29 エレメント シックス （プロダクション）（プロプライエタリィ） リミテッド Cubic boron nitride compact
WO2010119962A1 (en) * 2009-04-17 2010-10-21 株式会社タンガロイ Cubic boron nitride sintered compact and coated cubic boron nitride sintered compact
JP2015523954A (en) * 2012-05-31 2015-08-20 ダイヤモンド イノベイションズ インコーポレーテッド Sintered super-hard compact for cutting tools and its manufacturing method
JP2019065513A (en) * 2017-09-29 2019-04-25 三菱マテリアル株式会社 Drilling chip, drilling tool, and production method of drilling chip
JP6798648B1 (en) * 2019-12-16 2020-12-09 住友電気工業株式会社 Cubic boron nitride sintered body

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