JP2017150223A - Excavation tool, excavation rod and excavation bit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress breakage of an excavation rod due to bending of a male screw of the rod.SOLUTION: The excavation tool comprises an excavation bit having a bit body 11 centered on an axis O and an excavation rod having a rod body 1 centered on the axis O. A female screw 13b is formed in the skirt portion inner periphery of a rear end of the bit body 11, and a male screw 2 screwed in the female screw 13b is formed in a distal end of the rod body 1. A bit side tapered surface 13d of which the inner diameter gradually diametrically enlarges toward the rear end side, is formed in the rear end side more than the female screw 13b. A portion more rear than the male screw 2 is formed with a rod side tapered portion 3 having a rod side tapered surface 3a of which the outer diameter gradually diametrically enlarges toward the rear end side in a manner opposing the bit side tapered surface while the male screw 2 is screwed in the female screw 13b. The maximum outer diameter of the rod side tapered portion 3 is larger than the outer diameter of the rod body 1 on the more rear end side than the rod side tapered portion 3.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a drilling tool including a drilling bit having a female screw portion, a drilling rod having a male screw portion screwed into the female screw portion of the drilling bit, and a drilling rod and a drilling bit constituting the drilling tool. It is about.

  As such a drilling tool, for example, in Patent Document 1, the end of the sleeve (skirt portion) of the drilling bit is located on the rear end side of the end of the male screw portion of the drilling rod, and the inner diameter of the sleeve is the small diameter of the drilling rod. The outer diameter of the drilling rod is located between the extended surface of the outer peripheral surface of the sleeve and the extended surface of the inner peripheral surface of the sleeve. It is listed.

International Publication No. 03/042493

  Such excavation tools, excavation rods and excavation bits are used for excavation work in tunnels, mines, etc., and most of the excavation rod life is due to breakage from the external thread on the excavation bit side. The most ideal form of end-of-life of the excavating rod is due to wear of the thread of the male thread part, but in reality, there is no end to breakage due to excessive bending or overload acting on the male thread part.

  The cause of this breakage is an overload on the male thread portion due to the bending of the excavating rod. In excavation work of a tunnel, a drill rod is often used under severe conditions, and bending force generated by bending of a drill hole due to excessive thrust or the like acts on a small-diameter male screw portion to cause breakage. In addition, when excavating uneven ground where joints (fissures of the ground) exist obliquely with respect to the axis of the excavation tool, the excavation rod is guided diagonally when the excavation bit hits the joint. Bending occurs.

  Further, when the excavation bit is to be pulled out from the excavation hole together with the excavation rod bent in this way, the outer peripheral surface of the excavation rod is positioned between the extension surfaces of the inner and outer peripheral surfaces of the sleeve as in the excavation tool described in Patent Document 1. If it does, there exists a possibility that the outer peripheral part of the sleeve which protruded from the outer peripheral surface of the bent excavation rod may be caught in the opening part of the excavation hole opened jointly. This also causes a large resistance to act on the male thread portion of the excavation rod, resulting in an excessive load, which may cause breakage.

  The present invention has been made under such a background, and an object thereof is to provide an excavation tool, an excavation rod, and an excavation bit that can suppress breakage due to bending of a male thread portion of the excavation rod.

  In order to solve the above problems and achieve such an object, a drilling tool of the present invention includes a drill bit having a bottomed cylindrical bit body centered on an axis, and an axial shape centered on the axis. And a female threaded portion is formed on the inner periphery of the cylindrical skirt at the rear end of the bit body, and is screwed into the female threaded portion at the tip of the rod body. An excavation tool in which a male screw portion is formed, and a conical surface centered on the axis line whose inner diameter gradually increases toward the rear end side on the rear end side with respect to the female screw portion on the inner periphery of the skirt portion A bit-side tapered surface is formed, and on the rear end side of the male threaded portion of the rod body, the male threaded portion is screwed into the female threaded portion so as to face the bit-side tapered surface. The outer diameter gradually increases toward the rear end. A rod-side taper portion having a conical surface rod-side taper surface centering on the above-mentioned axis that expands the diameter is formed, and the maximum outer diameter of the rod-side taper portion is the rear end of the rod-side taper portion. It is characterized by being larger than the outer diameter of the rod body on the side.

  The excavation rod of the present invention is an excavation rod used for such an excavation tool, and has an axial rod body centered on the axis, and a male screw portion is provided at the tip of the rod main body. A rod-side taper having a conical-shaped rod-side taper surface centered on the above-mentioned axis whose outer diameter gradually increases toward the rear end side is formed on the rear end side from the male screw portion. A portion is formed, and the maximum outer diameter of the rod side taper portion is larger than the outer diameter of the rod body on the rear end side with respect to the rod side taper portion.

  Further, the excavation bit of the present invention is also an excavation bit used for the excavation tool as described above, and has a bottomed cylindrical bit body centered on the axis, and the cylindrical shape of the rear end portion of the bit main body. A female threaded portion is formed on the inner periphery of the skirt portion, and the rear end side of the inner peripheral portion of the skirt portion is centered on the axis whose inner diameter gradually increases toward the rear end side. A bit-side tapered surface having a conical surface is formed.

  In such excavation tools, excavation rods and excavation bits, in the rod body of the excavation rod, the rod-side taper surface that gradually increases in diameter toward the rear end side on the rear end side of the male thread portion at the front end portion thereof The rod-side taper portion is formed with a maximum outer diameter of the rod-side taper portion larger than the outer diameter of the rod body on the rear end side than the rod-side taper portion. The rigidity of the rod body in the portion can be improved, and the bending of the male screw portion itself can be suppressed.

  In addition, since the rod-side taper portion having a large outer diameter is formed on the tip end side of the rod body in this way, when the drilling bit hits the joint and the male screw portion should be bent, the drill rod and the drilling rod were to be pulled out from the drill hole. In this case, the first contact with the opening of the excavation hole to the joint can be the rear end surface of the rod side taper portion, so that a large resistance can be avoided from acting on the male screw portion. Furthermore, since the rear end surface of the rod side taper portion has a larger diameter than the male screw portion, the cross-sectional area is large, and the strength and rigidity are high. Therefore, even if a large resistance acts on this portion, the rod body breaks. And the excavation tool can be easily pulled out.

  The rod-side taper surface of the rod-side taper portion is rearward of the female screw portion on the inner periphery of the skirt portion of the bit body of the excavation bit when the male screw portion of the excavation rod is screwed into the female screw portion of the excavation bit. Since it faces the bit side taper surface formed on the end side, even if an overload due to excessive thrust acts on the drilling rod or the drilling bit hits the joint, the male screw part should be bent by any chance Since the bit side taper surface and the rod side taper surface are in contact with each other, it is possible to prevent the male screw portion from being further bent and broken.

  Here, the bit side taper surface and the rod side taper surface may be opposed to each other with an interval therebetween. In this case, the abutment between the bit side taper surface and the rod side taper surface is a contact between the rear end side portions of the conical taper surface whose diameter has been increased, so that a large abutment area can be secured. The bending of the screw portion can be further reliably suppressed. Further, the bit side taper surface and the rod side taper surface may be in close contact with each other. In this case, the bit side taper surface and the rod side taper surface are in contact with each other, so that the male screw portion It becomes possible to suppress the bending itself. Further, the bit side taper surface and the rod side taper surface are opposed to each other with a space therebetween, and a convex portion provided on at least one of the bit side taper surface and the rod side taper surface is formed on the other taper surface. In this case, the bending load of the male screw portion can be suppressed by the contact due to the contact of the convex portion.

  Also, by setting the maximum outer diameter of the rod side taper portion to be equal to or greater than the outer diameter of the skirt portion, the skirt portion does not protrude beyond the rod side taper portion. Even when the excavating rod is pulled out at the joint, it is possible to suppress an excessive load from being generated in the male screw portion and to further facilitate the pulling out.

  The taper angle formed by the bit side taper surface and the rod side taper surface with respect to the axis is an acute angle, but is preferably in the range of 1 ° to 30 °. If the taper angle is smaller than 1 °, especially when the bit side taper surface and the rod side taper surface face each other with a gap therebetween, There is a possibility that the contact area of the taper surface on the rod side cannot be ensured as described above, and conversely, if this taper angle is larger than 30 °, the bit side will be bent when the male thread is bent. There is a possibility that the taper surface and the rod-side taper surface cannot be reliably brought into contact with each other.

  As described above, according to the present invention, even if excessive thrust acts on the excavation rod or the excavation bit hits the joint, it is possible to suppress the bending of the male screw portion of the excavation rod. In addition, even if bending occurs, it is possible to suppress breakage of the male screw portion.

It is a side view which shows one Embodiment of the excavation rod of this invention. It is ZZ expanded sectional drawing in FIG. It is an expanded side view which shows one Embodiment of the excavation bit of this invention. FIG. 4 is an enlarged front view of the embodiment shown in FIG. 3. FIG. 4 is an enlarged side sectional view of the embodiment shown in FIG. 3. It is an expanded sectional side view of the front-end | tip part in one Embodiment of the excavation tool of this invention which attached the excavation bit of embodiment shown in FIG. 3 to the excavation rod of embodiment shown in FIG.

  1 and 2 show an embodiment of the excavation rod of the present invention, FIGS. 3 to 5 show an embodiment of the excavation bit of the present invention, and FIG. 6 shows the above embodiment. An embodiment of the excavation tool of the present invention in which the excavation bit of the above embodiment is attached to an excavation rod of the form is shown. The excavation rod of the present embodiment has a long shaft-shaped rod body 1 centered on the axis O by a metal material such as steel, and the excavation bit of the present embodiment is also made of a metal material such as steel. A bottomed cylindrical bit body 11 centering on the axis O is provided.

  The rod body 1 includes, in order from the front end side (left side in FIGS. 1 and 6) to the rear end side (right side in FIGS. 1 and 6), a male thread portion 2, a rod side taper portion 3, a stem portion 4, And the shank part 5 is integrally formed. In the rod body 1, a blow hole 6 having a circular cross section centering on the axis O having a constant inner diameter is formed so as to penetrate the rod body 1 along the axis O.

  In the present embodiment, the shank portion 5 is also a male screw portion, and the direction of twist is the same as that of the male screw portion 2 at the distal end portion of the rod body 1. This shank portion 5 is directly attached to a rotary shaft of a rock drill or the like, or is attached via one or a plurality of other excavation rods (joint rods) attached to the rotary shaft and coupled from the rock drill. The excavation tool according to the present embodiment excavates the ground by transmitting the rotational force around the given axis O and the thrust and striking force toward the tip end in the direction of the axis O to the excavation bit via the excavation rod.

  The stem portion 4 occupies most of the entire length of the rod body 1, and in this embodiment, the outer shape is a regular hexagonal shape as shown in FIG. 2 in a cross section perpendicular to the axis O, and circumscribes the stem portion 4. Is slightly larger than the diameter of the shank part 5 (the diameter of a circle circumscribing the top of the thread of the male thread part formed by the shank part 5). In addition, the short range in the direction of the axis O at the rear end of the stem portion 4 is formed in a cylindrical surface centered on the axis O having the same diameter as the circle circumscribed on the stem portion 4 and the stem portion 4. Between the rear end and the shank portion 5, a rod side constricted portion 7 having a concave curved cross section along the axis O and recessed inward is formed in an annular shape.

  Furthermore, the male thread part 2 at the most distal end of the rod body 1 is formed such that its diameter (diameter of a circle circumscribing the top of the thread of the male thread part 2) is the smallest in the rod body 1. Further, the front end surface of the male screw portion 2 (the front end surface of the rod main body 1) is a flat surface perpendicular to the axis O except for the opening of the blow hole 6, and a male surface located around the front end surface. A chamfer is applied to the outer peripheral portion of the tip of the screw portion 2.

  And the rod side taper part 3 located in the rear end side of this external thread part 2 increases an outer diameter gradually toward the rear end side in order toward the rear end side from the front end side to the outer peripheral surface. A conical surface-shaped rod-side tapered surface 3a with the axis O as the center, a cylindrical surface-shaped tapered surface 3b with the axis O connected to the rear end of the rod-side tapered surface 3a as the center, and the tapered portion cylinder A taper portion rear end surface 3c that connects the rear end of the surface 3b and the tip end of the stem portion 4 is formed, and the maximum outer diameter of the rod side taper portion 3 is greater on the rear end side than the rod side taper portion 3 It is formed so as to be larger than the outer diameter of the rod body 1.

  That is, in this embodiment, the outer diameter of the tapered portion cylindrical surface 3b extending from the rear end of the rod side tapered surface 3a is the maximum outer diameter of the rod side tapered portion 3, and the maximum outer diameter of the rod side tapered portion 3 is Of course, the diameter of the circle circumscribing the stem portion 4 and the diameter of the shank portion 5 are larger than the diameter of the male screw portion 2. A tapered rear end surface 3c that connects the rear end of the tapered cylindrical surface 3b and the distal end of the stem portion 4 intersects the tapered cylindrical surface 3b at an obtuse angle in the cross section along the axis O, and the outer periphery of the stem portion 4 It is formed so as to form a concave curve such as a concave arc having a large radius in contact with the surface.

  In the cross section along the axis O, the taper angle α formed by the rod-side tapered surface 3a with respect to the axis O is in the range of 1 ° to 30 °, and preferably in the range of 5 ° to 20 °. In this embodiment, the angle is 10 °. As shown in FIG. 1, the length of the rod side taper portion 3 in the direction of the axis O is shorter than that of the male screw portion 2, and the taper portion cylindrical surface 3b occupies the axis O direction in the rod side taper portion 3. The length is shorter than the length which the rod side taper surface 3a occupies in the axis O direction.

  On the other hand, in the excavation bit according to the embodiment of the present invention, the bottom portion of the bottomed cylindrical bit body 11 is directed to the front end side as the excavation portion 12, and the cylindrical skirt is directed to the excavation portion 12 and the rear end side. The part 13 is integrally formed. A circular face surface 12a that is perpendicular to the axis O and that is centered on the axis O is formed at the front end surface of the excavation portion 12, and the outer periphery of the face surface 12a is rearward toward the outer periphery. Gauge surfaces 12b are formed so as to be inclined toward the end sides. Drilling tips 14 made of a hard material such as cemented carbide are implanted perpendicularly to the face surfaces 12a and 12b on the face surfaces 12a and 12b, respectively. It is installed.

  Further, on the outer peripheral portion of the excavation part 12, a plurality of discharge grooves 12c of flouring extending in the direction of the axis O are formed at intervals in the circumferential direction so as to avoid the excavation tip 14 planted on the gauge surface 12b. Has been. Further, a blow hole 15 extending to the front end side along the axis O is formed on the bottom surface of the skirt portion 13 serving as the rear end surface of the excavation portion 12, and this blow hole 15 branches off in the middle and the face surface 12a. And at least one bottom surface of the plurality of discharge grooves 12c. The rear end surface of the excavation part 12 is a flat surface perpendicular to the axis O except for the opening of the blow hole 15, and the outer peripheral surface of the excavation part 12 is directed toward the front end side except for the discharge groove 12c. It has a conical surface with an axis O slightly inclined so as to go to the outer peripheral side.

  Further, on the inner periphery of the skirt portion 13, the front end side escape portion 13 a having a larger inner diameter than the above-mentioned diameter of the male screw portion 2 of the excavation rod and the male screw portion 2 are screwed in order from the front end side to the rear end side. The possible internal thread portion 13b, the rear end side escape portion 13c having a larger inner diameter than the diameter of the male screw portion 2 and the rear end side escape portion 13c are connected to the rear end side escape portion 13c, and the inner diameter gradually increases toward the rear end side. A conical bit-side tapered surface 13d centering on the axis O is formed. In the present embodiment, the bit-side tapered surface 13d is formed by screwing the male threaded portion 2 of the excavating rod into the female threaded portion 13b, and when the front end surface of the male threaded portion 2 contacts the rear end surface of the excavated portion 12. The rod side taper portion 3 is formed so as to be opposed to the rod side taper surface 3a with a slight gap W therebetween.

  Here, the taper angle β formed with respect to the axis O in the cross-section along the axis O by the bit side taper surface 13d is in the range of 1 ° to 30 °, like the rod side taper surface 3a. It is set within a range of 5 ° to 20 °, and is set to 10 ° in this embodiment, that is, equal to the taper angle α formed by the rod side taper surface 3a. Further, in the state where the male screw portion 2 is screwed into the female screw portion 13b as described above, the interval W between the rod side taper surface 3a and the bit side taper surface 13d is in a cross section along the axis O. The distance in the direction perpendicular to the rod-side tapered surface 3a and the bit-side tapered surface 13d is desirably 1 mm or less. In the excavation tool of this embodiment, the distance is 0.53 mm.

  Further, in the present embodiment, the outer peripheral surface of the skirt portion 13 is formed in a cylindrical surface centered on the axis O, and the tapered cylindrical surface 3b that is the maximum outer diameter of the rod side tapered portion 3 of the rod body 1 is formed. The outer diameter is equal to or larger than the outer diameter of the skirt portion 13, and is substantially equal to the outer diameter of the skirt portion 13 in this embodiment. The maximum outer diameter of the excavation bit is the outer peripheral end of the excavation tip 14 planted on the gauge surface 12b of the excavation part 12, and the diameter of the cylindrical surface centering on the axis O circumscribing the outer peripheral end is It is slightly larger than the outer diameter of the tapered cylindrical surface 3b. In addition, a cross section along the axis O is formed between the rear end of the excavation part 12 and the front end of the skirt part 13 in the outer peripheral surface of the bit body 11 and is recessed in a conical shape on the inner peripheral side toward the front end side. An annular bit side constricted portion 16 is formed which forms a concave curve and cuts to the outer peripheral side.

  The male threaded portion 2 of the drilling rod is screwed into the female threaded portion 13b on the inner periphery of the skirt portion 13 of such a drilling bit, and the drilling tool of this embodiment is configured as shown in FIG. In the excavation tool and the excavation rod thus configured, first, a conical surface centering on an axis O whose outer diameter gradually increases toward the rear end side toward the rear end side of the male screw portion 2 at the front end portion of the rod body 1. The rod-side taper portion 3 having a rod-side taper surface 3 a is formed, and the maximum outer diameter of the rod-side taper portion 3 is larger than the outer diameter of the rod body 1 on the rear end side than the rod-side taper portion 3. In other words, the entire rod body 1 has a maximum outer diameter. Therefore, the male threaded portion 2 can be supported with high strength and rigidity by the rod side tapered portion 3, and even when an excessive load is applied, the bending of the male threaded portion 2 can be suppressed.

  Also, when excavating the ground where the above joints exist, even when the drilling tool hits the joint and the male screw part 2 is bent, the outer diameter is the largest in this way. Since the large rod side taper portion 3 is formed on the rear end side of the male screw portion 2, it is not the rear end surface of the bit body 11 of the excavation bit that hits the opening portion of the excavation hole to the joint first. It can be set as the taper part rear end surface 3c of the taper part 3. Therefore, even if the taper portion rear end surface 3c is caught in the opening, the male screw portion 2 does not have a large resistance, and the male screw portion 2 is broken as in the case where the rear end surface of the bit body 11 is caught. Since the rod side taper portion 3 has high strength and high rigidity, it is possible to suppress breakage of the rod main body 1 from the taper rear end surface 3c and to facilitate pulling out. be able to.

  In particular, in the present embodiment, the maximum outer diameter of the rod side taper portion 3 is set to be equal to or larger than the outer diameter of the skirt portion 13 of the bit body 11, so that the skirt portion 13 is located on the outer peripheral side of the rod side taper portion 3. It does not protrude and is caught in the opening of the excavation hole, and it is possible to reliably prevent a large resistance from acting on the male screw portion. Moreover, the taper portion rear end surface 3c of the rod side taper portion 3 has a concave curved cross section along the axis O, and the outer peripheral surface of the excavating portion 12 of the bit body 11 is directed toward the outer peripheral side toward the front end side. Since the drilling tool is pulled out of the drilling hole so that it is guided by the concave curve and the conical surface even if these surfaces are caught in the opening, it suppresses breakage of the male screw part 2 As a result, the excavation tool can be reliably collected together with the excavation bit, and pulling out becomes easier.

  Further, in the excavation tool and excavation bit of the present embodiment, an axis O whose inner diameter gradually increases toward the rear end side is formed on the rear end side of the female thread portion 13b on the inner periphery of the skirt portion 13 of the bit body 11. A bit-side tapered surface 13d having a conical surface at the center is formed. When the male screw portion 2 is screwed into the female screw portion 13b, the bit-side tapered surface 13d is spaced from the rod-side tapered surface 3a of the excavating rod. Open up and face each other. Therefore, even if the male screw portion 2 is bent as described above and tilted together with the excavation bit, the bit body 11 is supported when the bit side taper surface 13d abuts the rod side taper surface 3a, and further the male screw Since the part 2 does not bend, it is possible to prevent the male screw part 2 from being broken.

  Moreover, the bit side taper surface 13d is in contact with the rod side taper surface 3a because the most widened rear end portion of the conical bit side taper surface 13d is partially at the rear end side of the rod side taper surface 3a. The contact is made by contacting the portion, and a large contact area can be secured. For this reason, it becomes possible to firmly support the inclined excavation bit and more reliably suppress the bending and breakage of the male screw portion 2.

  Furthermore, in the present embodiment, the taper angles α and β formed with respect to the axis O in the cross section along the axis O between the bit side taper surface 13d and the rod side taper surface 3a are in the range of 1 ° to 30 °. Accordingly, the bending and breakage of the male screw portion 2 can be further reliably suppressed. That is, if the taper angles α and β are smaller than 1 °, the contact area is reduced as described above unless the lengths of the bit side taper surface 13d and the rod side taper surface 3a in the direction of the axis O are increased. If the taper angles α and β are larger than 30 °, the bit side taper surface 13d and the rod side taper surface 3a are reliably brought into contact with each other when the male screw portion 2 is bent. There is a risk that it will not be possible to make contact.

  In the excavation tool of the present embodiment, the bit-side taper surface 13d faces the rod-side taper surface 3a of the excavation rod with a gap in a state where the male screw portion 2 is screwed into the female screw portion 13b as described above. However, the bit side tapered surface 13d and the rod side tapered surface 3a may be configured to be in close contact with each other in this screwed state. Also in this case, bending and breakage of the male screw portion 2 can be suppressed by the close contact between the bit side tapered surface 13d and the rod side tapered surface 3a.

  Further, at least one of the bit side taper surface 13d and the rod side taper surface 3a is provided with a convex portion that contacts the other, and the bit side taper surface 13d and the rod side taper surface 3a are opposed to each other with a space therebetween. However, this convex portion is point-contacted, line-contacted, or surface-contacted with the other of the bit-side tapered surface 13d and the rod-side tapered surface 3a, thereby supporting the bit body 11 and suppressing bending and breakage of the male screw portion 2. You may make it do.

DESCRIPTION OF SYMBOLS 1 Rod main body 2 Male thread part 3 Rod side taper part 3a Rod side taper surface 3b Tapered part cylindrical surface 3c Taper part rear end surface 4 Stem part 5 Shank part 11 Bit body 12 Excavation part 13 Skirt part 13b Female thread part 13d Bit side taper Surface 14 Drilling tip O Rod body 1 and bit body 11 axis α Tapered angle of rod side taper surface 3a with respect to axis O β Bit side taper surface 13d taper angle with respect to axis O W Rod side taper surface 3a and bit side taper surface 13d Interval

Claims (6)

A drilling bit having a bottomed cylindrical bit body centered on an axis, and a drilling rod having a shaft-shaped rod body centered on the axis, and an inner periphery of a cylindrical skirt portion at the rear end of the bit body Is a drilling tool in which a female screw part is formed, and a male screw part screwed into the female screw part is formed at the tip of the rod body,
On the rear end side of the inner periphery of the skirt portion, a conical bit side taper surface centering on the axis whose inner diameter gradually expands toward the rear end side is formed.
The outer diameter of the rod body gradually increases toward the rear end side facing the bit side taper surface with the male screw portion screwed into the female screw portion at the rear end side of the male screw portion of the rod body. A rod-side taper portion having a conical surface-shaped rod-side taper surface centering on the above-described axis to be formed is formed,
An excavation tool, wherein a maximum outer diameter of the rod side taper portion is larger than an outer diameter of the rod body on the rear end side of the rod side taper portion.   The bit-side taper surface and the rod-side taper surface are opposed to each other with a space therebetween, or are in close contact with each other, or are opposed to each other with a space therebetween, and at least of the bit-side taper surface and the rod-side taper surface. The excavation tool according to claim 1, wherein a convex portion provided on one side is in contact with the other tapered surface.   The excavation tool according to claim 1 or 2, wherein a maximum outer diameter of the rod side taper portion is equal to or larger than an outer diameter of the skirt portion.   4. The taper angle formed by the bit side taper surface and the rod side taper surface with respect to the axis is within a range of 1 to 30 degrees. The excavation tool according to claim 1. A drilling rod used for the drilling tool according to any one of claims 1 to 4,
The rod body has an axial rod centered on the axis, and a male threaded portion is formed at the tip of the rod body. A rod-side taper portion having a conical surface rod-side taper surface centering on the axis line where the outer diameter gradually increases is formed,
The excavation rod, wherein the maximum outer diameter of the rod side taper portion is larger than the outer diameter of the rod body on the rear end side of the rod side taper portion. A drilling bit used in the drilling tool according to any one of claims 1 to 4,
It has a bottomed cylindrical bit body centered on the axis, and a female thread portion is formed on the inner periphery of the cylindrical skirt portion at the rear end of the bit body,
On the rear end side of the inner periphery of the skirt portion, a bit-side tapered surface having a conical surface centered on the axis whose diameter gradually increases toward the rear end side is formed. Features a drilling bit.

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