JP7026597B2 - Drilling bit - Google Patents

Description

In the present invention, a gauge surface is formed on the outer periphery of the tip of the bit body, and a face surface is formed on the inner circumference of the gauge surface. Also, a gauge tip and a face tip provided with a high-hardness hard layer are respectively arranged, and the present invention relates to a drilling bit used for mining drilling, construction drilling, geothermal drilling, O & G drilling, and the like.

As such an excavation bit, a gauge surface is formed on the outer periphery of the tip of the bit body so as to be inclined toward the rear end side toward the outer peripheral side, and the tip side of the bit body is formed on the inner circumference of the gauge surface. A facing face surface is formed, and a gauge tip and a face tip made of cemented carbide are arranged on the gauge surface and the face surface by projecting the tip portion and embedding the rear end portion in the bit body. It is known that excavation is performed by applying a striking force to the tip side in the axial direction while rotating the main body around the axis.

For example, Patent Document 1 describes that a button tip having a diameter of 14 mm is arranged on a bit body having a gauge surface having a diameter of 165 mm. Further, Patent Document 2 describes that a gauge tip having a diameter of 10 mm is arranged in a bit body forming a drilling hole having a diameter of 48 mm. Further, Patent Document 3 describes that a gauge tip having a diameter of 10 mm is arranged on a bit body having a gauge surface having a diameter of 45 mm.

However, when an attempt is made to excavate a cemented carbide having a UCS (uniaxial compressive strength) of 150 MPa or more with an excavation bit having a gauge tip or a face tip made of such a cemented carbide, the hardness of the cemented carbide is Hv1400 to Hv1500. Therefore, the gauge tip and face tip are worn out at an early stage, making excavation impossible.

Therefore, for example, in Patent Documents 4 and 5, for example, a gauge chip provided with a base material made of such a cemented carbide or a face chip has a cemented carbide on the surface of the gauge surface or the tip portion protruding from the face surface. The one provided with a hard layer made of a polycrystalline diamond sintered body having a hardness higher than that of the base material is described.

U.S. Pat. No. 4,743,515 U.S. Patent Application Publication No. 2013/018785 U.S. Patent Application Publication No. 2012/0325558 U.S. Patent Application Publication No. 2001/0047890 U.S. Patent Application Publication No. 2010/0025114

By the way, in an excavation bit in which a gauge tip or a face tip made of a super hard alloy as described in Patent Documents 1 to 3 is arranged, the gauge tip or the face tip itself is gradually worn, and thus during excavation. Since the reflected stress received by the excavation bit from the bedrock is consumed, the reflected stress received by the bit body is low, and damage other than wear is unlikely to occur on the gauge tip and face tip.

However, a gauge tip or face tip provided with a hard layer having a hardness higher than that of the cemented carbide is disposed on the surface of the tip portion of the base material made of the cemented carbide as described in Patent Documents 4 and 5. In the drilling bit, the gauge tip and face tip are hardly worn by this hard layer, so when drilling carbide, the reflected stress received by the gauge tip and face tip as a reaction force of the striking force is large through the hard layer. It propagates to the material and concentrates.

For this reason, the fatigue of the base metal of the gauge tip and face tip becomes large, the rear end portion of the base metal embedded in the bit body is sheared, and the tip portion provided with the hard layer falls off for excavation. It may be impossible. In particular, shearing of the rear end portion of the base metal due to such concentration of reflected stress is performed as the gauge tip center line, which is the center line of the rear end portion of the columnar base metal, moves toward the tip end side of the bit body. In the gauge tip arranged so as to face the side, the reaction force when the excavation bit hits the bedrock acts diagonally with respect to the center line of the gauge tip, so that it is likely to occur.

The present invention has been made under such a background, and as described above, a gauge tip hard layer having a hardness higher than that of the gauge tip base material is provided on the surface of the tip portion of the gauge tip base material. The purpose of the excavation bit is to provide an excavation bit capable of preventing the shearing of the base metal due to the concentration of the reflected stress on the gauge tip, even when excavating cemented carbide.

In order to solve the above problems and achieve such an object, the present invention has the above-mentioned bit body on the outer periphery of the tip portion of the bit body which is rotated around the axis and receives a striking force toward the tip side in the axial direction. A conical pedestal-shaped gauge surface that inclines toward the rear end side toward the outer peripheral side is formed, and a circular face surface facing the tip side in the axial direction is formed on the inner circumference of this gauge surface. A gauge tip and a face tip are arranged on the surface and the face surface, respectively, and the gauge tip has a cylindrical rear end portion embedded in the bit body and gradually increases from the rear end portion toward the tip side. A gauge tip base material having a reduced diameter and a tip portion protruding from the gauge surface is provided, and a gauge chip hard layer having a hardness higher than that of the gauge tip base material is provided on the surface of the tip portion of the gauge tip base material. The gauge chip center line, which is the center line of the columnar rear end portion, is arranged so as to face the outer peripheral side toward the tip end side of the bit body, and the radius of the rear end portion of the gauge chip. The ratio R ² / D (mm ² / inch) of the square R ² (mm ² ) of R (mm) to the diameter D (inch) of the gauge surface of the bit body is in the range of 18 to 25. It is characterized by that.

In the excavation bit configured in this way, the square R ² (mm ² ) of the radius R (mm) of the rear end of the gauge chip, which is a molecule of the ratio R ² / D (mm ² / inch), is a gauge. Gauge at the rear end of the chip It is an index of the size of the cross-sectional area perpendicular to the center line of the chip, and the diameter (outer diameter) D (inch) of the gauge surface of the bit body, which is the denominator, is the size of the tip surface of the bit body. It becomes an index. That is, the ratio R ² / D (mm ² / inch) is an index of how much the area of the rear end portion of one gauge tip occupies on the front end surface of the bit body.

Here, the ratio R ² / D (mm ² / inch) in the excavation bit described in Patent Documents 1 to 3 is 14 or less. On the other hand, in the drilling bit of the present invention, the ratio R ² / D (mm ² / inch) is large in the range of 18 to 25, and therefore the rear end of each gauge tip has a larger cross-sectional area. It is embedded in the bit body and arranged.

Therefore, this gauge tip is provided with a gauge tip hard layer having a hardness higher than that of this gauge tip base material on the surface of the tip portion of the gauge tip base material protruding from the gauge surface, and the gauge tip center line. Even if the insert is arranged so as to move toward the outer peripheral side toward the tip side of the bit body, it is possible to disperse the reflected stress acting during excavation, and the rear end of the gauge tip base material can be dispersed. It is possible to prevent shearing of the portion.

Here, if the ratio R ² / D (mm ² / inch) is so small that it is less than 18, there is a possibility that the reflected stress cannot be dispersed in this way to prevent shearing of the rear end portion of the gauge tip base material. There is. On the other hand, when this ratio R ² / D (mm ² / inch) is so large that it exceeds 25, the cross-sectional area of the rear end portion of the gauge tip base material becomes too large and the gauge tip can be arranged on the gauge surface of the bit body. There is a risk that the required drilling efficiency will not be ensured due to the reduced number of chips.

Further, the hardness of the gauge tip hard layer is preferably twice or more the hardness of the gauge tip base material, and more preferably Hv2800 or more. If the hardness of the gauge chip hard layer is lower than twice the hardness of the gauge chip base material or less than Hv2800, the gauge chip hard layer gradually wears together with the gauge chip base material when excavating super hard rock. As a result, shearing due to the concentration of reflected stress does not occur, but there is a risk that the life of the gauge tip will be shortened due to wear.

Further, it is desirable that the hardness of the gauge tip base material is in the range of Hv1400 to Hv1500. If the hardness of the gauge tip base material is low enough to be lower than Hv1400, even if the gauge tip hard layer is provided on the surface of the tip of the gauge tip, the gauge tip hard layer cannot be reliably supported and is carbide. When excavating rocks, the tip of the gauge tip may be crushed together with the hard layer of the gauge tip. On the other hand, if the hardness of the gauge tip base material is so high that it exceeds Hv1500, the reflected stress may not be sufficiently dispersed when excavating the cemented carbide.

As a material that satisfies the relationship between the hardness of the gauge chip base material and the hardness of the gauge chip hard layer as described above and the gauge chip base material and the gauge chip hard layer, the gauge chip base material is super hard. It is preferably an alloy, and the gauge chip hard layer is preferably a polycrystalline diamond sintered body (PDC) or a polycrystalline cBN (cubic boron nitride) sintered body (PcBN).

Furthermore, it is desirable that the radius R (mm) of the rear end portion of the gauge tip base material is within the range of 6 to 10 (mm). If the radius R (mm) of the rear end portion of the gauge tip base material is less than 6 (mm), the size of the tip portion that hits the bedrock such as cemented carbide becomes small, and the excavation efficiency may be impaired. On the other hand, if the radius R (mm) of the rear end of the gauge tip base material exceeds 10 (mm), the gauge tip can be arranged only on the bit body having a large gauge surface diameter D (inch). With a bit body of a certain size, the number of gauge chips that can be arranged is limited, and the excavation efficiency may be impaired.

As described above, according to the present invention, the reflected stress acting on the gauge tip when excavating cemented carbide can be dispersed, the shearing of the base metal due to the concentration of the reflected stress can be prevented, and the long-term effect can be achieved. Therefore, stable excavation can be performed.

It is a side view which shows the 1st Embodiment of this invention. It is a front view of the embodiment shown in FIG. FIG. 2 is a cross-sectional view taken along the line ZOZ in FIG. It is a side view which shows the 2nd Embodiment of this invention. It is a front view of the embodiment shown in FIG. It is a rear view of the embodiment shown in FIG. FIG. 5 is a cross-sectional view taken along the line YOY in FIG. FIG. 5 is a cross-sectional view taken along the line ZOZ in FIG. It is a side view which shows the 3rd Embodiment of this invention. It is a front view of the embodiment shown in FIG. It is a rear view of the embodiment shown in FIG. FIG. 10 is a cross-sectional view taken along the line ZOZ in FIG.

1 to 3 show the first embodiment of the present invention, FIGS. 4 to 8 show the second embodiment of the present invention, and FIGS. 9 to 12 show the first embodiment of the present invention. 3 shows the embodiment, and the same reference numerals are given to the parts common to each other. The bit body 1 in the first to third embodiments is formed of a metal material such as a steel material into a bottomed cylindrical shape centered on the axis O.

Here, in these first to third embodiments, the bottomed portion side of the bit body 1 is the tip end side (right side in FIGS. 1, FIG. 3, FIG. 4, FIG. 7, FIG. 8, FIG. 9, and FIG. 12). The cylindrical part is the rear end side (left side in FIGS. 1, 3, 4, 7, 8, 9, and 12), the bottomed portion is the tip portion, and the cylindrical portion is the rear end portion. It is said that. Further, the direction away from the axis O in the radial direction with respect to the axis O is the outer peripheral side, and the direction closer to the axis O is the inner peripheral side.

A female screw portion 1A that twists around the axis O is formed on the inner peripheral portion of the rear end portion of the bit body 1 in the first to third embodiments. Such an excavation bit is rotated in a certain direction around the axis O via the excavation rod by screwing a male thread portion at the tip of the excavation rod (not shown) into the female thread portion 1A in the axis O direction. A striking force is applied to the tip side, and a rock mass such as cemented carbide having a UCS of 150 MPa or more is crushed and excavated by a gauge tip 2 and a face tip 3 arranged at the tip of the bit body 1.

Further, in the first to third embodiments, the outer diameter of the tip portion of the bit body 1 is made larger than the outer diameter of the rear end portion. The outer peripheral surface of the tip portion extends toward the outer peripheral side while drawing a concave curve in a cross section along the axis O from the rear end portion toward the tip side, and then draws a straight line intersecting the concave curve at an obtuse angle to the outer circumference. It extends to the side.

Further, on the front end surface of the bit body 1, a conical countertop-shaped gauge surface 4 is formed on the outer peripheral portion, which is inclined toward the rear end side toward the outer peripheral side, and an axis line is formed on the inner circumference of the gauge surface 4. A circular face surface 5 facing the tip end side in the O direction is formed. The face surface 5 is formed in a plane shape perpendicular to the axis O. Further, the gauge angle θ (°), which is the inclination angle formed by the gauge surface 4 with respect to the face surface 5 in the cross section along the axis O, is 25 (°) in the present embodiment. The gauge chip 2 is embedded in the gauge surface 4 and arranged, and the face chip 3 is embedded in the face surface 5 and arranged.

Of these first to third embodiments, in the first embodiment, the diameter (outer diameter) D of the gauge surface 4 is 1.75 (inch), that is, about 45 (mm). Further, in the first embodiment, the outer peripheral surface of the rear end portion of the bit body 1 is formed in a tapered shape that extends from the tip end portion toward the rear end portion and then slightly shrinks in diameter after extending at a constant outer diameter. Further, it extends again with a constant outer diameter and reaches the rear end surface of the bit body 1.

Further, in this first embodiment, two first dusting grooves 6A having a wide circumferential width are located on the outer periphery of the tip end portion of the bit body 1 so as to be opposite to each other in the circumferential direction with the axis O in between. It is formed so as to extend in the O direction. Further, between these two first dusting grooves 6A, two second dusting grooves 6B having a width and a groove depth in the circumferential direction smaller than those of the first powdering groove 6A are located in the axis O direction. It is formed to extend to.

In this embodiment, the two first and second dusting grooves 6A and 6B are the first and second dusting grooves 6A and 6B as shown in FIG. 2 when viewed from the tip side in the O direction of the axis. The straight lines connecting the centers in the width directions are arranged so as to be orthogonal to each other on the axis O. Further, the first and second dusting grooves 6A and 6B are opened on the gauge surface 4 of the tip end portion of the bit body 1 on the tip end side, and along the axis O on the rear end side of the tip end portion on the rear end side. It is a through groove that opens in the part where the cross section draws a concave curve.

Of these, the first dusting groove 6A has a slightly concave curved surface on the inner peripheral side of the bit body 1 from both ends in the circumferential direction toward the center as shown in FIG. 2 when viewed from the tip side in the O direction of the axis. After being dented, it is formed to form a convex curved surface and bulge toward the outer peripheral side, but even the most bulging portion in the central part in the circumferential direction is formed so as to be located on the inner peripheral side of the diameter of the gauge surface 4. There is. Further, as shown in FIG. 3, the first dusting groove 6A is inclined toward the outer peripheral side toward the rear end side of the bit body 1 in the cross section along the axis O.

On the other hand, the second dusting groove 6B has a concave curved bottom surface such as a concave arc as shown in FIG. 2 when viewed from the tip side in the O direction of the axis, and the distance of the opening in the gauge surface 4 from the axis O. Is larger than the distance from the axis O of the opening in the gauge surface 4 of the first dusting groove 6A. Further, the groove bottom of the second dusting groove 6B is formed so as to extend substantially parallel to the axis O in the cross section along the axis O as shown in FIG. 3, and the outer peripheral surface of the tip end portion of the bit body 1 is formed. The groove depth from is reduced toward the rear end side.

Furthermore, the bit body 1 is formed with a blow hole 7 from the bottom surface of the inner peripheral portion of the rear end portion facing the rear end side toward the front end side along the axis O. As shown in FIG. 3, the blow hole 7 branches into two small-diameter first branch holes 7A at the tip of the bit body 1 and extends toward the outer peripheral side toward the tip side, and the axis line as shown in FIG. When viewed from the tip end side in the O direction, the second powder grooves 6B are opened at equal intervals in the circumferential direction on a straight line connecting the centers in the width direction on the outer peripheral side of the face surface 5. Further, the blow hole 7 is branched into two small-diameter second branch holes 7B even between the first branch hole 7A and the bottom surface of the inner peripheral portion of the bit body 1 as shown in FIG. It extends toward the outer peripheral side toward the side and opens to the groove bottom of the second dusting groove 6B.

In the present embodiment, the gauge tip 2 and the face tip 3 are button tips. That is, the rear ends of the gauge tip 2 and the face tip 3 are formed in a columnar shape centered on the gauge tip center line C2 and the face tip center line C3, respectively, and the tip portion has the rear end portion. It has a radius equal to the radius of the cylinder to be formed, and is formed into a convex hemisphere that gradually shrinks in diameter from the rear end toward the tip.

The gauge tip 2 has a rear end portion press-fitted, shrink-fitted, chill-fitted, etc. into a hole having a circular cross section formed between the first and second dusting grooves 6A and 6B adjacent to each other in the circumferential direction on the gauge surface 4. As described above, it is embedded in the bit body 1 and the tip portion is projected from the gauge surface 4. Therefore, in the present embodiment, four gauge chips 2 are arranged, and these gauge chips 2 have the same shape and the same size as each other.

Further, the gauge tip center line C2 of these gauge tips 2 is arranged so as to be directed toward the outer peripheral side toward the tip end side of the bit body 1, and in the present embodiment, the cross section along the axis O is shown in FIG. As shown in, it is perpendicular to the gauge surface 4. The rotation loci formed by these four gauge chips 2 around the axis O of the bit body 1 are the same.

Further, in the present embodiment, as shown in FIG. 2, the face tip 3 is on a straight line connecting the centers of the two second dusting grooves 6B in the width direction on the face surface 5 when viewed from the tip side in the O direction of the axis line. The rear end portion is embedded and fixed in the bit body 1 by press fitting, shrink fitting, cold fitting or the like in the formed hole portion having a circular cross section, and the tip portion is projected from the face surface 5. Therefore, in the present embodiment, the two face chips 3 are arranged at equal intervals in the circumferential direction, and these face chips 3 have the same shape and the same size as each other.

Further, the face chip center line C3 of these face chips 3 is arranged so as to extend in the axis O direction of the bit body 1, is parallel to the axis O in the present embodiment, and is perpendicular to the face surface 5. It is said that. The rotation loci formed by the two face chips 3 around the axis O of the bit body 1 also match. As shown in FIG. 2, the gauge tip 2 is arranged so that the edge portion on the outer peripheral side of the bit body 1 slightly protrudes from the outer peripheral edge of the gauge surface 4 when viewed from the tip end side in the O direction of the axis.

Further, these gauge tip 2 and face tip 3 include a gauge tip base material 2A and a face tip base material 3A in which the tip portion and the rear end portion are integrally formed, and the gauge tip base material 2A and the face tip base material. It includes a gauge tip base material 2A provided on the surface of the tip portion of 3A, a gauge tip hard layer 2B and a face tip hard layer 3B having a hardness higher than that of the face tip base material 3A. The radius of the convex hemisphere formed by the tips of the gauge tip 2 and the face tip 3 is the radius of the surface of the gauge tip hard layer 2B and the face tip hard layer 3B.

Here, the gauge tip base material 2A and the face tip base material 3A are metal materials having a hardness in the range of Hv1400 to Hv1500, and are WC-based cemented carbides in the present embodiment. On the other hand, the gauge tip hard layer 2B and the face tip hard layer 3B have a hardness more than twice that of the gauge tip base material 2A and the face tip base material 3A, and are Hv2800 or more, and are polycrystalline in the present embodiment. It is a diamond sintered body (PDC) or a polycrystalline cBN (cubic boron nitride) sintered body (PcBN).

Of these gauge chips 2 and face chips 3, the gauge chip 2 has a radius of the rear end (radius of the rear end of the gauge chip base material 2A) R (mm) squared R ² (mm ² ). The ratio ^R2 / D (mm ² / inch) of the gauge surface 4 of the bit body 1 to the diameter D (inch) is set to be within the range of 18 to 25. Specifically, in the present embodiment, the radius D of the gauge surface 4 is 1.75 (inch) as described above, whereas the diameter of the rear end portion of the gauge tip 2 is 13 (mm). Therefore, the radius R (mm) is 6.5 (mm), the square R ² of the radius R (mm) is 42.25 (mm ² ), and the square R ² (mm) of this radius R (mm). The ratio R ² / D (mm ² / inch) of ² ) to the diameter D (inch) of the gauge surface 4 is 24.1 (mm ² / inch).

In this first embodiment, the radius of the rear end portion of the face tip 3 and the radius of the convex hemisphere formed by the tip portion are the radius R (mm) of the rear end portion of the gauge tip 2 and the convex hemisphere formed by the tip portion. It is smaller than the radius R (mm) formed by the eggplant.

Next, in the second embodiment shown in FIGS. 4 to 8, the diameter D of the gauge surface 4 is 3.5 (inch) and is about 89 (mm), whereas the rear end of the gauge tip 2 is set. The diameter of the part is 16 (mm) and the radius R (mm) is 8 (mm), so the square R ² of the radius R (mm) is 64.0 (mm ² ), and this radius R The ratio R ² / D (mm ² / inch) of the square R ² (mm ² ) of (mm) to the diameter D (inch) of the gauge surface 4 is 18.29 (mm ² / inch). Further, the gauge angle θ (°), which is the inclination angle formed by the gauge surface 4 with respect to the face surface 5 in the cross section along the axis O, is 30 (°) in the present embodiment.

In this second embodiment, the outer diameter of the rear end side portion of the rear end portion of the bit body 1 is one step larger than that of the front end side portion of the rear end portion. However, the outer diameter of the rear end side portion of this rear end portion is smaller than the diameter D (inch) of the gauge surface 4 which is the outer diameter of the tip portion. Further, as shown in FIG. 6 when viewed from the rear end side in the axis O direction of the bit body 1, the outer periphery of the rear end side portion of the rear end portion has a third reel having a bottom surface of a concave curve such as a concave arc. A plurality of powder grooves 6C (8 in this embodiment) are formed at equal intervals in the circumferential direction.

On the other hand, on the outer periphery of the tip portion of the bit body 1, two first dusting grooves 6A having a wide circumferential direction extend in the circumferential direction opposite to each other in the axial direction O with the axis O in between. Along with being formed, between these two first powder grooves 6A, three second powder grooves having a width and a groove depth in the circumferential direction smaller than those of the first powder groove 6A are formed. The 6B is formed so as to extend in the axial direction O at equal intervals in the circumferential direction together with the first dusting groove 6A. A total of eight positions of the first and second dusting grooves 6A and 6B in the circumferential direction are aligned with the positions of the third dusting groove 6C in the circumferential direction as shown in FIG.

The second dusting groove 6B in the second embodiment is V-shaped as shown in FIG. 5 when viewed from the tip side in the O-direction of the axis, and is shown in FIG. 7 in the cross section along the axis O. As described above, similarly to the first dusting groove 6A, the bit is inclined toward the outer peripheral side toward the rear end side of the bit body 1. The gauge tips 2 are arranged on the gauge surface 4 between the first and second dusting grooves 6A and 6B at equal intervals in the circumferential direction. Therefore, in the present embodiment, a total of eight gauge tips are arranged. 2 is arranged.

Further, from the bottom surface of the rear end portion of the bit body 1 facing the rear end side, as shown in FIGS. 5 and 8, four blow holes 7 move toward the outer peripheral side toward the tip end side of the bit body 1. It extends toward the face surface 5 and opens at equal intervals in the circumferential direction. The face chips 3 are arranged between the openings in the face surface 5 of the blow holes 7, and therefore, in the present embodiment, the four face chips 3 are arranged at equal intervals in the circumferential direction. To.

Of these four face chips 3, two face chips (face chips arranged vertically in FIG. 5) 3 have two first reels as shown in FIG. 5 when viewed from the tip side in the O direction of the axis. It is arranged near the outer peripheral edge of the face surface 5 on the inner peripheral side of the powder groove 6A. Further, one of the remaining two face tips 3 (the face tip 3 arranged on the left side in FIG. 5) is two groups of three formed between the two first dusting grooves 6A. On the inner peripheral side of the central second powder groove 6B in the circumferential direction of the three second powder grooves 6B of one group among the second powder grooves 6B of the above, from the above two face tips 3. Is also arranged on the inner peripheral side.

Further, the other one of the remaining two face tips 3 (the face tip 3 arranged on the right side in FIG. 5) is central in the circumferential direction of the three second powder grooves 6B of the other group. It is arranged on the inner peripheral side of the second dusting groove 6B and further on the inner peripheral side than one of the remaining two face chips 3, and the rotation of these four face chips 3 around the axis O. The trajectories are designed to overlap. In this second embodiment and the third embodiment described below, the face tip 3 has the same shape and size as the gauge tip 2.

Furthermore, in the third embodiment shown in FIGS. 9 to 12, the diameter D of the gauge surface 4 is 4 (inch), which is about 102 (mm), whereas the rear end portion of the gauge tip 2 is located. The diameter is 18 (mm) and the radius R (mm) is 9 (mm), so the square R ² of the radius R (mm) is 81 (mm ² ) of this radius R (mm). The ratio R ² / D (mm ² / inch) of the square R ² (mm ² ) to the diameter D (inch) of the gauge surface 4 is 20.25 (mm ² / inch).

Also in this third embodiment, the outer diameter of the rear end side portion of the rear end portion of the bit body 1 is in a range smaller than the diameter D (inch) of the gauge surface 4 as in the second embodiment. The bit is made one step larger than the tip end side portion of the rear end portion of the bit body 1, and eight third dusting grooves 6C are formed at equal intervals in the circumferential direction on the outer peripheral portion thereof. Further, the gauge angle θ (°), which is the inclination angle formed by the gauge surface 4 with respect to the face surface 5 in the cross section along the axis O, is 35 (°) in the present embodiment.

On the other hand, in this third embodiment, on the outer periphery of the tip portion of the bit body 1, four second portions having the same V-shaped width and groove depth as shown in FIG. 10 when viewed from the tip side in the O direction of the axis. The dusting grooves 6B are formed at equal intervals in the circumferential direction, and the positions of these second dusting grooves 6B in the circumferential direction are the positions of every other third dusting groove 6C in the circumferential direction. It is matched. Then, in the third embodiment, two gauge tips 2 are arranged between the second dusting grooves 6B adjacent to each other in the circumferential direction.

Further, in the third embodiment, the three blow holes 7 are directed toward the outer peripheral side as the three blow holes 7 are directed toward the tip end side of the bit body 1 from the bottom surface facing the rear end side of the inner peripheral portion of the rear end portion of the bit body 1. It extends and opens to the face surface 5. Of these three blow holes 7, two blow holes (blow holes that open vertically in FIG. 10) 7 are two gauges located on opposite sides of the axis O in the circumferential direction of the bit body 1. The remaining one blow hole (blow hole opened on the left side in FIG. 10) 7 which is opened between the chips 2 is the center of the two blow holes 7 in the circumferential direction of the bit body 1, and these two blows are made. It is open on the inner peripheral side of the hole 7.

Further, in this third embodiment, five face chips 3 are arranged on the face surface 5. Of these, the four face tips 3 have face surfaces 5 on the inner peripheral side of the four second powder grooves 6B in the circumferential direction of the bit body 1 as shown in FIG. 10 when viewed from the tip side in the O direction of the axis. It is arranged at equal intervals near the outer peripheral edge of the. On the other hand, on the remaining one, the face tip 3 is on the opposite side of the face surface 5 from the opening of the remaining one blow hole 7 with the axis O interposed therebetween, and on the inner peripheral side of the four face chips 3 above. These four face chips 3 and the rotation loci around the axis O are arranged so as to overlap each other.

In the excavation bit of the first to third embodiments as described above, the male threaded portion of the excavation rod is screwed into the female threaded portion 1A on the inner circumference of the rear end portion of the bit body as described above, and the axis line is passed through the excavation rod. While being rotated around O, a striking force is applied to the tip side in the O direction of the axis, and the gauge tip 2 and the face tip 3 crush rocks such as cemented carbide to perform excavation. During this excavation, a fluid such as compressed air is ejected from the blow hole 7 through the excavation rod, and the powder generated by the excavation is discharged from the powder grooves 6A to 6C to the rear end side of the bit body 1. do.

In the excavation bit having the above configuration, the ratio of the square R ² (mm ² ) of the radius R (mm) of the rear end portion of the gauge tip 2 to the diameter D (inch) of the gauge surface 4 of the bit body 1. R ² / D (mm ² / inch) is set in the range of 18 to 25, which is set larger than that of the conventional drilling bits described in Patent Documents 1 to 3. This ratio R ² / D (mm ² / inch) is an index of how much the area of the rear end portion of one gauge tip 2 occupies on the tip surface of the bit body 1 as described above. In the excavation bit having the above configuration, the rear end portion of each gauge tip 2 is embedded and arranged in the bit body 1 with a larger cross-sectional area.

Therefore, the gauge tip hard layer 2B having a hardness higher than that of the gauge tip base material 2A is provided on the surface of the tip portion of the gauge tip base material 2A protruding from the gauge surface 4 of the bit body 1 of the gauge tip 2. Even so, the reflected stress acting on the gauge tip 2 as a reaction force of the striking force during excavation can be diffused at the rear end portion of the gauge tip base material 2A having a large cross-sectional area.

Therefore, the gauge tip center line C2 is inclined toward the outer peripheral side toward the tip end side of the bit body, and the reaction force acts diagonally on the gauge tip center line C2. However, it is possible to prevent shearing of the rear end portion of the gauge tip base material 2A due to the concentration of reflected stress, and it is possible to prevent the tip end portion of the gauge tip 2 to be excavated from falling off.

Here, when the ratio R ² / D (mm ² / inch) is small enough to be less than 18, shearing of the rear end portion of the gauge tip base material 2A is surely prevented by dispersing the reflected stress as described above. It may not be possible. Further, if this ratio R ² / D (mm ² / inch) is large enough to exceed 25, the cross-sectional area of the rear end portion of the gauge tip base material 2A becomes too large, and by embedding this rear end portion, the bit The number of gauge chips 2 arranged on the gauge surface 4 of the main body 1 is reduced, the excavation speed is lowered, and the required excavation efficiency may not be ensured.

Further, in the first to third embodiments, the gauge tip hard layer 2B on the surface of the tip of the gauge tip 2 is a polycrystalline diamond sintered body (PDC) or a polycrystalline cBN (cubic boron nitride) sintered body ( PcBN), the hardness of which is Hv2800 or more, which is twice or more the hardness of the gauge chip base material 2A made of cemented carbide. Therefore, even in the excavation of rocks such as cemented carbide having a UCS of 150 MPa or more, it is possible to maintain the life of the gauge tip 2 and perform stable excavation over a long period of time.

That is, if the hardness of the gauge tip hard layer 2B is lower than twice the hardness of the gauge tip base material 2A or less than Hv2800, the gauge tip hard layer 2B is used when excavating the superhard rock as described above. Will gradually wear together with the gauge tip base material 2A, and shearing due to the concentration of reflected stress will not occur, but the wear may cause the gauge tip 2 and the bit body 1 to reach their end of life at an early stage.

Further, in the first to third embodiments, the hardness of the gauge tip base material 2A of the gauge tip 2 is set to be in the range of Hv1400 to Hv1500, which ensures reliable reflection during excavation of cemented carbide. While the stress is dispersed to prevent the rear end of the gauge tip 2 from being sheared, it is possible to prevent the tip of the gauge tip 2 from being crushed.

That is, when the hardness of the gauge tip base material 2A is so low that it is lower than Hv1400, even if a high hardness gauge tip hard layer 2B is provided on the surface of the tip portion, the gauge tip hard layer 2B is used when excavating cemented carbide. The tip of the gauge tip 2 may be crushed together with the gauge tip hard layer 2B because it cannot be supported. On the other hand, if the hardness of the gauge tip base material 2A is so high that it exceeds Hv1500, the reflected stress may not be sufficiently dispersed.

Furthermore, in the first to third embodiments, the radius R (mm) of the rear end portion of the gauge tip 2 (rear end portion of the gauge tip base material 2A) is within the range of 6 to 10 (mm). It is said that it is possible to reliably maintain the excavation efficiency. That is, when the radius R (mm) of the rear end portion of the gauge tip base material 2A is less than 6 (mm), the size of the tip portion of the gauge tip 2 that hits the bedrock such as cemented carbide becomes smaller, and the excavation efficiency becomes smaller. May be damaged.

Further, when the radius R (mm) of the rear end portion of the gauge tip base material 2A exceeds 10 (mm), the gauge tip 2 is arranged only on the bit body 1 having a large diameter D (inch) of the gauge surface 4. The number of gauge chips 2 that can be arranged on the bit body 1 of a certain size is limited, which may lead to a decrease in excavation efficiency.

Although not shown, in the excavation bit where the diameter D of the gauge surface 4 of the bit body 1 is 2.5 (inch) and is about 64 (mm), the diameter of the rear end portion of the gauge tip 2 is 14. (Mm) and the radius R (mm) is 7 (mm), so the square R ² of the radius R (mm) is 49 (mm ² ) and the square R of this radius R (mm). The ratio R ² / D (mm ² / inch) of ² (mm ² ) to the diameter D (inch) of the gauge surface 4 may be 19.6 (mm ² / inch).

Also, although not shown in the figure, in the excavation bit where the diameter D of the gauge surface 4 of the bit body 1 is 3.0 (inch) and is about 76 (mm), the diameter of the rear end portion of the gauge tip 2 is 16 (mm) and the radius R (mm) is 8 (mm), so the square R ² of the radius R (mm) is 64 (mm ² ) and the square of this radius R (mm). The ratio R ² / D (mm ² / inch) of R ² (mm ² ) to the diameter D (inch) of the gauge surface 4 may be 21.3 (mm ² / inch).

Further, in the first to third embodiments, the gauge tip 2 and the face tip 3 are button tips having a convex hemispherical tip, but the tip gradually follows the tip side. It is also possible to apply the present invention to an excavation bit in which a gauge tip or a face tip formed in a reduced diameter cannonball shape is arranged. Similarly, the present invention is applied to an excavation bit in which a tip portion is formed in a conical shape that gradually shrinks in diameter toward the tip side, but the tip thereof is arranged with a gauge tip or a face tip rounded into a convex spherical shape. It is also possible.

Hereinafter, the effects of the present invention will be described with reference to examples of the present invention. In this embodiment, an excavation bit having a gauge tip hard layer 2B made of a polycrystalline diamond sintered body (PDC) based on the first embodiment described above is manufactured, and the excavation bit has a UCS of 180 MPa to 199 MPa. The carbide rocks of the copper mine were excavated, the excavation length until the excavation bit reached the end of its life was measured, and the cause of the end of its life was investigated. This is referred to as Example 1. Therefore, the ratio R ² / D (mm ² / inch) of the excavation bit of this embodiment is 24.1 (mm ² / inch). The excavation conditions were that the rotation speed of the bit body 1 was 250 (rpm), the striking force was 18 (kW), and the striking number was 68 (Hz).

Further, as a comparative example with respect to Example 1, an excavation bit having the same configuration as that of Example 1 except that the entire gauge tip is formed of cemented carbide and the diameter of the rear end portion is 9 (mm). A gauge chip hard layer made of polycrystalline diamond sintered body (PDC) is provided on the surface of the tip of the gauge chip base material made of cemented carbide, but the diameter of the rear end part of the gauge tip base material is 9 (mm). The excavation bit was manufactured and excavated under the same excavation conditions as in Example 1, the excavation length until the excavation bit reached the end of its life was measured, and the cause of the end of the life was investigated. These are referred to as Comparative Examples 1 and 2 in order. Therefore, the ratio ^R2 / D (mm ² / inch) of the excavation bits of Comparative Examples 1 and 2 is 11.5 (mm ² / inch).

As a result, the excavation length of Comparative Example 1 was 12 (m), and the cause of the life of the excavation bit was normal wear of the gauge tip. Further, the excavation length of Comparative Example 2 was 37 (m), and the cause of the life of the excavation bit was the shearing of the rear end portion of the gauge tip base material. On the other hand, the excavation length of Example 1 was 160 (m), which was more than ten times longer than that of Comparative Example 1 and four times or more longer than that of Comparative Example 2. The cause of the life of Example 1 was normal wear of the gauge tip 2 and partial loss.

Next, an excavation bit having a gauge tip hard layer 2B made of a polycrystalline diamond sintered body (PDC) based on the above-mentioned second embodiment is manufactured, and the excavation bit is used to manufacture a silver mine having a UCS of 162 MPa to 222 MPa. The cemented carbide was excavated, and the excavation length until the excavation bit reached the end of its life was measured as in Example 1, and the cause of the end of its life was investigated. This is referred to as Example 2. Therefore, the ratio R ² / D (mm ² / inch) of the excavation bit of the second embodiment is 18.29 (mm ² / inch). The excavation conditions were that the rotation speed of the bit body 1 was 140 (rpm), the striking force was 25 (kW), and the striking number was 55 (Hz).

Further, as a comparative example with respect to Example 2, an excavation bit having the same configuration as that of Example 2 except that the entire gauge tip is formed of cemented carbide and the diameter of the rear end portion is 13 (mm). A gauge chip hard layer made of polycrystalline diamond sintered body (PDC) is provided on the surface of the tip of the gauge chip base material made of cemented carbide, but the diameter of the rear end part of the gauge tip base material is also 13 (mm). ) Was manufactured, and excavation was performed under the same excavation conditions as in Example 2, the excavation length until the excavation bit reached the end of its life was measured, and the cause of the end of its life was investigated. These are referred to as Comparative Examples 3 and 4 in order. Therefore, the ratio R ² / D (mm ² / inch) of the excavation bits of Comparative Examples 3 and 4 is 12.09 (mm ² / inch).

As a result, the excavation length of Comparative Example 3 was 32 (m), and the cause of the life of the excavation bit was normal wear of the gauge tip. Further, the excavation length of Comparative Example 4 was 170 (m), and the cause of the life of the excavation bit was the shearing of the rear end portion of the gauge tip base material. On the other hand, the excavation length of the excavation bit of Example 2 was 300 (m), which was nearly ten times longer than that of Comparative Example 3 and nearly twice as long as that of Comparative Example 4. The cause of the life of Example 2 was normal wear of the gauge tip 2 and partial loss.

Further, an excavation bit having a gauge tip hard layer 2B made of a polycrystalline diamond sintered body (PDC) based on the above-mentioned third embodiment is manufactured, and the excavation bit is used to produce a gold mine having a UCS of 185 MPa to 190 MPa. The excavation of the polycrystalline rock was performed, the excavation length until the excavation bit reached the end of its life was measured as in Examples 1 and 2, and the cause of the end of the life was investigated. This is referred to as Example 3. Therefore, the ratio R ² / D (mm ² / inch) of the excavation bit of the third embodiment is 20.25 (mm ² / inch). The excavation conditions were that the rotation speed of the bit body 1 was 95 (rpm), the striking force was 40 (kW), and the striking number was 62 (Hz).

Further, as a comparative example with respect to Example 3, an excavation bit having the same configuration as that of Example 3 except that the entire gauge tip is formed of cemented carbide and the diameter of the rear end portion is 13 (mm). A gauge chip hard layer made of polycrystalline diamond sintered body (PDC) is provided on the surface of the tip of the gauge chip base material made of cemented carbide, but the diameter of the rear end part of the gauge tip base material is 16 (mm). The excavation bit was manufactured, and excavation was performed with these excavation bits under the same excavation conditions as in Example 3, the excavation length until the excavation bit reached the end of its life was measured, and the cause of the end of the life was investigated. These are referred to as Comparative Examples 5 and 6 in order. Therefore, the ratio R ² / D (mm ² / inch) of the excavation bit of Comparative Example 5 is 10.6 (mm ² / inch), and the ratio R ² / D (mm ² ) of the excavation bit of Comparative Example 6 is. / Inch) is 16 (mm ² / inch).

As a result, the excavation length of Comparative Example 5 was 25 (m), and the cause of the life of the excavation bit was normal wear of the gauge tip. Further, the excavation length of Comparative Example 6 was 68 (m), and the cause of the life of the excavation bit was the shearing of the rear end portion of the gauge tip base material. On the other hand, the excavation length of the excavation bit of Example 3 was 240 (m), which was nearly ten times longer than that of Comparative Example 5 and nearly four times longer than that of Comparative Example 6. The cause of the life of Example 3 was normal wear of the gauge tip 2 and partial loss.

1 Bit body 2 Gauge tip 2A Gauge tip base material 2B Gauge tip hard layer 3 Face tip 3A Face tip base material 3B Face tip hard layer 4 Gauge surface 5 Face surface 6A-6C Flour groove 7 Blow hole 7A, 7B Branch hole C2 Gauge tip center line C3 Face tip center line R Radius of the rear end of gauge tip 2 D Gauge surface diameter O Axis of bit body 1 θ Gauge angle

Claims (5)

A conical pedestal-shaped gauge surface is formed on the outer periphery of the tip of the bit body, which is rotated around the axis and receives a striking force toward the tip side in the axial direction, and is inclined toward the rear end side toward the outer periphery side of the bit body. At the same time, a circular face surface facing the tip side in the axial direction is formed on the inner circumference of the gauge surface, and a gauge tip and a face tip are arranged on each of the gauge surface and the face surface, respectively.
The gauge tip is a gauge tip base material having a columnar rear end portion embedded in the bit body and a tip portion whose diameter is gradually reduced toward the tip side from the rear end portion and protrudes from the gauge surface. In addition, a gauge tip hard layer having a hardness higher than that of the gauge tip base material is provided on the surface of the tip portion of the gauge tip base material, and the gauge tip center line which is the center line of the columnar rear end portion is provided. It is arranged so as to go toward the outer peripheral side toward the tip side of the bit body.
The ratio R ² / D (mm ² / inch) of the square R ² (mm ² ) of the radius R (mm) of the rear end of the gauge tip to the diameter D (inch) of the gauge surface of the bit body. Excavation bit characterized by being in the range of 18-25. The excavation bit according to claim 1, wherein the hardness of the gauge tip hard layer is at least twice the hardness of the gauge tip base material. The excavation bit according to claim 1 or 2, wherein the hardness of the gauge tip hard layer is Hv2800 or more. The excavation bit according to any one of claims 1 to 3, wherein the hardness of the gauge tip base material is in the range of Hv1400 to Hv1500. The excavation according to any one of claims 1 to 4, wherein the radius R (mm) of the rear end portion of the gauge tip base material is within the range of 6 to 10 (mm). bit.

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