JP6679039B1

JP6679039B1 - Drill bit

Info

Publication number: JP6679039B1
Application number: JP2020009816A
Authority: JP
Inventors: 政孝本多
Original assignee: エポコラム機工株式会社
Priority date: 2020-01-24
Filing date: 2020-01-24
Publication date: 2020-04-15
Anticipated expiration: 2040-01-24
Also published as: JP2021116570A

Abstract

【課題】高密度の砂礫地盤や転石・巨石の混在地盤などの硬質な地盤の掘削をも行うことができる掘削ビットを提供すること。【解決手段】本発明では、回転する掘削体（２０）に装着され、回転方向に向けて掘削しながら先方に向けて進行する掘削ビット（２３，６１〜６４）において、掘削面（４７）と所定の逃げ角（α）を形成する平面状の逃げ面（４８）を進行方向に向けて凸状に形成するとともに、掘削面（４７）と直交する面（４９）と所定のすくい角（β）を形成する平面状のすくい面（５０）を掘削方向に向けて凸状に形成し、凸状の逃げ面（４８）の先端と凸状のすくい面（５０）の先端との交差部分に形成されるビット先端（６０）を円弧面とすることにした。【選択図】図５PROBLEM TO BE SOLVED: To provide an excavation bit capable of excavating hard ground such as high-density gravel ground or mixed ground of boulders and megaliths. According to the present invention, an excavation bit (23, 61 to 64) mounted on a rotating excavation body (20) and traveling toward the forward direction while excavating in the rotating direction is used as an excavation surface (47). A plane clearance surface (48) forming a predetermined clearance angle (α) is formed in a convex shape in the traveling direction, and a surface (49) orthogonal to the excavation surface (47) and a predetermined rake angle (β). ) Is formed in a convex shape toward the excavation direction, and is formed at the intersection of the tip of the convex flank surface (48) and the tip of the convex rake surface (50). The tip (60) of the formed bit is to be an arc surface. [Selection diagram] Fig. 5

Description

本発明は、回転する掘削体に装着され、回転方向に向けて掘削しながら先方に向けて進行する掘削ビットに関するものである。 The present invention relates to a drill bit that is mounted on a rotating excavation body and that travels forward while excavating in a rotating direction.

地盤の掘削や改良などの工事において、地盤を掘削するために掘削装置が使用されている。この掘削装置では、モーター等の駆動源に接続された回転軸の先端に掘削体が設けられている。掘削体は、回転軸に取付けられた掘削翼体に地盤の掘削を行う掘削ビットを設けている。そして、掘削装置では、回転軸の回転に伴って掘削翼体を回転させ、掘削ビットで地盤を掘削する（たとえば、特許文献１参照。）。 Excavation equipment is used to excavate the ground in construction such as excavation and improvement of the ground. In this excavator, an excavation body is provided at the tip of a rotary shaft connected to a drive source such as a motor. The excavation body is provided with an excavation bit for excavating the ground on an excavation wing body attached to a rotary shaft. Then, in the excavation device, the excavation blade body is rotated along with the rotation of the rotary shaft, and the excavation bit excavates the ground (for example, refer to Patent Document 1).

この掘削ビットは、掘削体の回転に伴って回転方向に向けて掘削しながら先方（鉛直下向き又は水平方向など）に向けて進行することになる。 The excavation bit advances toward the forward direction (vertically downward or horizontal direction) while excavating in the rotation direction as the excavation body rotates.

そこで、掘削ビットには、掘削する地盤（掘削面）からの抵抗を軽減するために、掘削面と所定の逃げ角を形成する逃げ面と、掘削面と直交する面と所定のすくい角を形成するすくい面とが形成されている。 Therefore, in order to reduce the resistance from the ground to be excavated (excavation surface), the excavation bit is formed with a flank surface that forms a predetermined clearance angle with the excavation surface and a surface that is orthogonal to the excavation surface and a predetermined rake angle. A rake face is formed.

そして、従来の掘削ビットでは、逃げ面とすくい面とが交差する先端部分が先鋭形状に形成されている。 In the conventional drill bit, the tip portion where the flank and the rake face intersect is formed in a sharp shape.

特開２００２−３３９６８０号公報JP, 2002-339680, A

ところが、上記従来の掘削ビットでは、逃げ面とすくい面とが交差する先端部分が先鋭形状に形成されていたために、高密度の砂礫地盤や転石・巨石の混在地盤などの硬質な地盤の掘削時等に、先端部分が容易に摩耗や損傷して掘削性能が低下するおそれがあった。 However, in the above-mentioned conventional drilling bit, the tip part where the flank and the rake face intersect is formed in a sharp shape, so when excavating hard ground such as high-density gravel ground or mixed ground of boulders and megaliths. In addition, the tip portion may be easily worn or damaged and the excavation performance may be deteriorated.

そこで、請求項１に係る本発明では、回転する掘削体に装着され、回転方向に向けて掘削しながら先方に向けて進行する掘削ビットにおいて、掘削面と所定の逃げ角を形成する平面状の逃げ面を進行方向に向けて凸状に形成するとともに、掘削面と直交する面と所定のすくい角を形成する平面状のすくい面を掘削方向に向けて凸状に形成し、凸状の逃げ面の先端と凸状のすくい面の先端との交差部分に形成されるビット先端を円弧面とすることにした。 Therefore, in the present invention according to claim 1, in an excavating bit that is mounted on a rotating excavation body and advances toward the forward direction while excavating in the rotating direction, a planar shape that forms a predetermined clearance angle with the excavating surface. The flank is formed in a convex shape in the traveling direction, and the flat rake surface that forms a predetermined rake angle with the surface orthogonal to the excavation surface is formed in a convex shape in the excavation direction to form a convex relief. The tip of the bit formed at the intersection of the tip of the surface and the tip of the convex rake face is an arc surface.

また、請求項２に係る本発明では、前記請求項１に係る本発明において、前記逃げ面を進行方向に対して左右に形成した平面状の左右逃げ面と左右逃げ面の間に形成した平面状の中央逃げ面とで構成するとともに、前記すくい面を掘削方向に対して左右に形成した平面状の左右すくい面と左右すくい面の間に形成した平面状の中央すくい面とで構成し、左右逃げ面と左右すくい面の先端部分に平面状の左右先端面を形成し、左右先端面と中央逃げ面と中央すくい面とで囲まれる中央先端面を前記円弧状のビット先端とすることにした。 Further, in the present invention according to claim 2, in the present invention according to claim 1, a flat surface formed between the left and right flanks and the flat flanks formed on the left and right with respect to the traveling direction. With a central flank face, the rake face is composed of a planar left and right rake face formed left and right with respect to the excavation direction and a flat center rake face formed between the left and right rake faces, The left and right flanks and the left and right rake faces are formed with flat left and right tip faces, and the central tip face surrounded by the left and right tip faces, the central flank face, and the central rake face is made the arc-shaped bit tip. did.

また、請求項３に係る本発明では、前記請求項２に係る本発明において、前記中央逃げ面及び中央すくい面並びに左右先端面を先端側から基端側に向けて縮幅することにした。 Further, in the present invention according to claim 3, in the present invention according to claim 2, the central flank, the central rake face, and the left and right tip surfaces are narrowed from the tip end side toward the base end side.

また、請求項４に係る本発明では、前記請求項１〜請求項３のいずれかに係る本発明において、前記すくい面を屈曲させて、先端側で掘削面と直交する面と正のすくい角を形成し、基端側で掘削面と直交する面と負のすくい角を形成することにした。 Further, in the present invention according to claim 4, in the present invention according to any one of claims 1 to 3, the rake face is bent to form a positive rake angle with a surface orthogonal to the excavation surface on the tip side. To form a negative rake angle with the surface orthogonal to the excavation surface on the base end side.

また、請求項５に係る本発明では、前記請求項１〜請求項４のいずれかに係る本発明において、前記逃げ面及びすくい面を、基端側の母材部と、母材部よりも硬質の先端側の超硬部とで形成することにした。 Further, in the present invention according to claim 5, in the present invention according to any one of claims 1 to 4, the flank and the rake face are more than the base material portion on the base end side and the base material portion. It was decided to form it with a hard tip side super hard part.

また、請求項６に係る本発明では、前記請求項５に係る本発明において、前記超硬部を前記母材部に着脱可能とすることにした。 Further, in the present invention according to claim 6, in the present invention according to claim 5, the cemented carbide portion can be attached to and detached from the base material portion.

そして、本発明では、以下に記載する効果を奏する。 And the present invention has the following effects.

すなわち、本発明では、回転する掘削体に装着され、回転方向に向けて掘削しながら先方に向けて進行する掘削ビットにおいて、掘削面と所定の逃げ角を形成する平面状の逃げ面を進行方向に向けて凸状に形成するとともに、掘削面と直交する面と所定のすくい角を形成する平面状のすくい面を掘削方向に向けて凸状に形成し、凸状の逃げ面の先端と凸状のすくい面の先端との交差部分に形成されるビット先端を円弧面とすることにしているために、硬質な地盤の掘削時等でもビット先端の摩耗や損傷を抑制することができ、掘削性能の低下を抑制することができる。 That is, in the present invention, in a drill bit that is mounted on a rotating excavation body and travels forward while excavating in the direction of rotation, a flat flank that forms a predetermined clearance angle with the excavation surface is used as a traveling direction. The rake face and the plane rake face that form a predetermined rake angle with the face orthogonal to the excavation face are formed in a convex shape toward the excavation direction, and the tip of the convex flank face and the convex face Since the tip of the bit formed at the intersection with the tip of the rake face is an arc surface, it is possible to suppress wear and damage of the tip even when excavating hard ground, etc. It is possible to suppress deterioration of performance.

特に、前記逃げ面を進行方向に対して左右に形成した平面状の左右逃げ面と左右逃げ面の間に形成した平面状の中央逃げ面とで構成するとともに、前記すくい面を掘削方向に対して左右に形成した平面状の左右すくい面と左右すくい面の間に形成した平面状の中央すくい面とで構成し、左右逃げ面と左右すくい面の先端部分に平面状の左右先端面を形成し、左右先端面と中央逃げ面と中央すくい面とで囲まれる中央先端面を前記円弧状のビット先端とすることにした場合には、ビット先端で掘削した土砂等を中央及び左右の逃げ面とすくい面とに分散させて掘削する地盤（掘削面）から受ける抵抗を低減することができる。 In particular, the flank is composed of a planar right and left flanks formed on the left and right with respect to the traveling direction and a planar central flank formed between the left and right flanks, and the rake face with respect to the excavation direction. Consists of a left and right flat rake surface and a flat center rake surface formed between the left and right rake surfaces, and a left and right flank surface and left and right flat rake surfaces with a flat left and right tip surface However, when the central tip end face surrounded by the left and right tip faces, the central flank face and the central rake face is to be the arc-shaped bit tip end, the earth and sand excavated at the bit tip end is the central and left and right flank faces. It is possible to reduce the resistance received from the ground (excavation surface) that is excavated by being dispersed in the rake face.

また、前記中央逃げ面及び中央すくい面並びに左右先端面を先端側から基端側に向けて縮幅することにした場合には、ビット先端で掘削した土砂等を中央の逃げ面やすくい面から左右の逃げ面やすくい面へと良好に分散させることができ、掘削する地盤（掘削面）から受ける抵抗をより一層低減することができる。 Further, when the central flank, the central rake face, and the left and right tip surfaces are to be narrowed from the tip side to the base end side, the earth and sand excavated at the tip of the bit is easily flanked at the center. The flanks can be easily dispersed on the right and left flanks, and the resistance received from the ground to be excavated (excavated surface) can be further reduced.

また、前記すくい面を屈曲させて、先端側で掘削面と直交する面と正のすくい角を形成し、基端側で掘削面と直交する面と負のすくい角を形成することにした場合には、強度を保持しつつ掘削する地盤（掘削面）から受ける抵抗を低減することができる。 Further, when the rake face is bent to form a positive rake angle with the face orthogonal to the excavation face on the tip side and a negative rake angle with the face orthogonal to the excavation face on the base end side In addition, it is possible to reduce the resistance received from the ground (excavation surface) to be excavated while maintaining the strength.

また、前記逃げ面及びすくい面を、基端側の母材部と、母材部よりも硬質の先端側の超硬部とで形成することにした場合には、先端側での摩耗や損傷を防止することができる。 Further, when the flank and the rake face are formed by the base material portion on the base end side and the cemented carbide portion on the tip end side that is harder than the base material portion, wear and damage on the tip end side Can be prevented.

また、前記超硬部を前記母材部に着脱可能とすることにした場合には、超硬部の交換によって掘削ビットの長寿命化を図ることができる。 Further, in the case where the cemented carbide portion can be attached to and detached from the base material portion, replacement of the cemented carbide portion can prolong the life of the drill bit.

地盤改良装置を示す側面図。The side view which shows the ground improvement apparatus. 掘削装置を示す側面図。The side view which shows a drilling device. 同平面図。FIG. 実施例１に係る掘削ビットを示す正面図（ａ）、平面図（ｂ）、右側面図（ｃ）、底面図（ｄ）。The front view (a), the top view (b), the right side view (c), and the bottom view (d) which show the drilling bit which concerns on Example 1. 同掘削状態を示す説明図。Explanatory drawing which shows the same excavation state. 実施例２に係る掘削ビットを示す正面図（ａ）、平面図（ｂ）、右側面図（ｃ）、底面図（ｄ）。A front view (a), a plan view (b), a right side view (c), and a bottom view (d) showing an excavating bit according to a second embodiment. 実施例３に係る掘削ビットを示す正面図（ａ）、平面図（ｂ）、右側面図（ｃ）、底面図（ｄ）。A front view (a), a plan view (b), a right side view (c), and a bottom view (d) showing an excavating bit according to a third embodiment. 実施例４に係る掘削ビットを示す正面図（ａ）、平面図（ｂ）、右側面図（ｃ）、底面図（ｄ）。The front view (a), the top view (b), the right side view (c), and the bottom view (d) which show the drilling bit which concerns on Example 4. 同掘削状態を示す説明図。Explanatory drawing which shows the same excavation state. 実施例５に係る掘削ビットを示す正面図（ａ）、平面図（ｂ）、右側面図（ｃ）、底面図（ｄ）。A front view (a), a plan view (b), a right side view (c), and a bottom view (d) showing an excavating bit according to a fifth embodiment.

以下に、本発明に係る掘削ビットの具体的な構成について図面を参照しながら説明する。なお、以下の説明では、本発明に係る掘削ビットを地盤改良装置の掘削装置に適用した場合について説明するが、これに限られず、本発明に係る掘削ビットは、地盤を垂直方向又は水平方向等に掘削するための各種の掘削装置に適用することができる。 Hereinafter, a specific configuration of the drill bit according to the present invention will be described with reference to the drawings. In the following description, the case where the excavation bit according to the present invention is applied to the excavation device of the ground improvement device will be described, but the present invention is not limited to this, and the excavation bit according to the present invention may have the ground vertically or horizontally. It can be applied to various drilling devices for drilling.

図１〜図３に示すように、地盤改良装置１は、地盤２を掘削するとともに、掘削した土壌と地盤改良材（固化材）とを撹拌混合することで、地盤２の強度や性状を改良するものである。この地盤改良装置１は、重機３の前端部に支柱４を立設し、この支柱４に掘削装置５を昇降自在に取付けている。この掘削装置５には、地盤改良材供給機構６がスイベルジョイント７を介して接続されている。地盤改良材供給機構６は、地盤改良材貯留タンク８と水槽９とを地盤改良材混合プラント10に接続するとともに、地盤改良材混合プラント10に地盤改良材吐出ポンプ11を接続して、地盤改良材を掘削装置５に供給するように構成している。 As shown in FIGS. 1 to 3, the ground improvement device 1 excavates the ground 2 and improves the strength and properties of the ground 2 by stirring and mixing the excavated soil and the ground improvement material (solidifying material). To do. In this ground improvement device 1, a column 4 is erected at a front end of a heavy machine 3, and an excavator 5 is attached to the column 4 so as to be vertically movable. A ground improvement material supply mechanism 6 is connected to the excavator 5 via a swivel joint 7. The soil improvement material supply mechanism 6 connects the soil improvement material storage tank 8 and the water tank 9 to the soil improvement material mixing plant 10, and also connects the soil improvement material discharge pump 11 to the soil improvement material mixing plant 10 to improve the soil. The material is supplied to the excavator 5.

掘削装置５は、支柱４の前側部に昇降支持体12を昇降自在に取付け、この昇降支持体12に駆動体13を取付け、駆動体13に上下方向に伸延させた掘削軸14の基端部（上端部）を取付け、掘削軸14の先端部（下端部）に回転掘削部15を取付けている。ここで、回転掘削部15は、回転によって掘削を行うものであり、地盤改良装置１では、地盤２の掘削に加えて掘削した地盤と地盤改良材との撹拌・混合を行う機能をも有している。 The excavation device 5 has an elevation support 12 attached to the front side of the support column 4 so that the elevation support 12 can be moved up and down, a drive 13 is attached to the elevation support 12, and the base end of an excavation shaft 14 extended vertically in the drive 13. (Upper end portion) is attached, and the rotary excavating portion 15 is attached to the tip end portion (lower end portion) of the excavating shaft 14. Here, the rotary excavator 15 excavates by rotation, and the ground improvement device 1 also has a function of agitating and mixing the excavated ground and the ground improving material in addition to the excavation of the ground 2. ing.

駆動体13は、掘削軸14を構成する内側軸16と外側軸17とに駆動モータ18を反転変速機19を介して接続している。 The drive body 13 has a drive motor 18 connected to an inner shaft 16 and an outer shaft 17 that form an excavation shaft 14 via a reversing transmission 19.

掘削軸14は、同軸上に回転中心軸を配置した中空円筒状の内側軸16と外側軸17とで二重管状に形成されている。掘削軸14は、内側軸16の先端部を外側軸17の先端部よりも下方へ向けて突出させている。これらの内側軸16又は外側軸17は、駆動モータ18を駆動することで、反転変速機19の作用で相対的に反対方向へ向けて回転する。 The excavation shaft 14 is formed in a double tubular shape by a hollow cylindrical inner shaft 16 and an outer shaft 17 which are coaxially arranged with a rotation center shaft. The excavation shaft 14 has a tip end portion of the inner shaft 16 protruding downward from a tip end portion of the outer shaft 17. By driving the drive motor 18, the inner shaft 16 or the outer shaft 17 is rotated in the opposite direction by the action of the reversing transmission 19.

回転掘削部15は、掘削軸14の先端部（下端部）に掘削体20と撹拌翼21とを先端側から順に取付けている。 The rotary excavator 15 has an excavator 20 and a stirring blade 21 attached to the tip (lower end) of the excavation shaft 14 in order from the tip.

掘削体20は、内側軸16の先端部外周面に２個の平板状の掘削翼体22を円周方向へ向けて180度の間隔をあけて外方へ向けて放射状に取付け、各掘削翼体22の下部に複数個の掘削ビット23を間隔をあけて着脱自在に取付けている。掘削体20は、内側軸16の回転に伴って掘削翼体22,22が回転し、掘削ビット23で地盤２を掘削する。 The excavation body 20 has two flat plate-shaped excavation blade bodies 22 radially attached to the outer peripheral surface of the tip end portion of the inner shaft 16 at an interval of 180 degrees in the circumferential direction toward the outside. A plurality of drill bits 23 are detachably attached to the lower part of the body 22 at intervals. In the excavation body 20, the excavation blade bodies 22, 22 rotate with the rotation of the inner shaft 16, and the excavation bit 23 excavates the ground 2.

撹拌翼21は、最内側撹拌翼24と、その外周側に配置される内側撹拌翼25と、さらにその外周側に配置される外側撹拌翼26とで構成している。 The stirring blade 21 includes an innermost stirring blade 24, an inner stirring blade 25 arranged on the outer peripheral side thereof, and an outer stirring blade 26 arranged further on the outer peripheral side thereof.

最内側撹拌翼24は、外側軸17の先端部外周面に２個の平板状の最内側撹拌翼体27を円周方向へ向けて180度の間隔をあけて外方へ向けて放射状に取付けている。 The innermost stirring blade 24 has two flat plate-shaped innermost stirring blades 27 radially attached to the outer peripheral surface of the outer shaft 17 at an interval of 180 degrees in the circumferential direction. ing.

内側撹拌翼25は、内側軸16の先端部に２個の内側撹拌翼体28を円周方向へ向けて180度の間隔をあけて外方へ向けて放射状に取付けている。各内側撹拌翼体28は、外方下部へ向けて傾斜状に伸延する内側撹拌翼上部片29と、下方へ向けて垂直状に伸延する内側撹拌翼中途部片30と、外方上部へ向けて傾斜状に伸延する内側撹拌翼下部片31とで、中途部を外方へ向けて膨出させた側面視で略コ字状に形成している。各内側撹拌翼体28は、内側撹拌翼下部片31を内側軸16の先端部側に取付けるとともに、内側撹拌翼上部片29を環状体32に取付け、環状体32を外側軸17の外周面に回動自在に遊嵌させている。また、各内側撹拌翼体28は、内側撹拌翼上部片29の上部や内側撹拌翼中途部片30の内側部や外側部に撹拌片33,34,35を取付けるとともに、内側撹拌翼中途部片30と内側軸16との間に連結片36を取付けている。 The inner stirring blade 25 has two inner stirring blades 28 radially attached to the tip of the inner shaft 16 outwardly at intervals of 180 degrees in the circumferential direction. Each inner stirring blade body 28 has an inner stirring blade upper piece 29 extending obliquely toward the outer lower side, an inner stirring blade intermediate piece 30 vertically extending downward, and an outer upper direction. And the lower part 31 of the inner stirring blade extending in a slanting manner, the middle part is formed to have a substantially U-shape in a side view with the part being bulged outward. In each inner stirring blade body 28, the inner stirring blade lower piece 31 is attached to the tip end side of the inner shaft 16, the inner stirring blade upper piece 29 is attached to the annular body 32, and the annular body 32 is attached to the outer peripheral surface of the outer shaft 17. It is rotatably fitted loosely. Further, each inner stirring blade body 28, while attaching the stirring pieces 33, 34, 35 to the upper portion of the inner stirring blade upper piece 29 and the inner portion and outer portion of the inner stirring blade middle portion piece 30, the inner stirring blade middle portion piece. A connecting piece 36 is attached between 30 and the inner shaft 16.

外側撹拌翼26は、外側軸17の先端部に３個の外側撹拌翼体37を円周方向へ向けて120度の間隔をあけて外方へ向けて放射状に取付けている。各外側撹拌翼体37は、外方下部へ向けて傾斜状に伸延する外側撹拌翼上部片38と、下方へ向けて垂直状に伸延する外側撹拌翼中途部片39と、外方上部へ向けて傾斜状に伸延する外側撹拌翼下部片40とで、中途部を外方へ向けて膨出させた側面視で略コ字状に形成している。各外側撹拌翼体37は、外側撹拌翼上部片38を外側軸17の先端部側に取付けるとともに、外側撹拌翼下部片40を環状体41に取付け、環状体41を内側軸16の外周面に回動自在に遊嵌させている。また、各外側撹拌翼体37は、外側撹拌翼上部片38の下部や外側撹拌翼中途部片39の内側部に撹拌片42,43を取付けている。 The outer stirring blade 26 has three outer stirring blades 37 radially attached to the tip of the outer shaft 17 outwardly at intervals of 120 degrees in the circumferential direction. Each outer stirring blade body 37 has an outer stirring blade upper piece 38 extending obliquely downward to the outside, an outer stirring blade intermediate piece 39 extending vertically downward, and an outer upper stirring piece 39. And the lower part 40 of the outer stirring blade extending in a slanting shape, the middle part is bulged outward and is formed in a substantially U shape in a side view. In each outer stirring blade body 37, the outer stirring blade upper piece 38 is attached to the tip end side of the outer shaft 17, the outer stirring blade lower piece 40 is attached to the annular body 41, and the annular body 41 is attached to the outer peripheral surface of the inner shaft 16. It is rotatably fitted loosely. Further, in each outer stirring blade body 37, stirring pieces 42, 43 are attached to the lower part of the outer stirring blade upper piece 38 and the inner side of the outer stirring blade intermediate piece 39.

地盤改良装置１は、以上に説明したように構成しており、本発明の要部となる掘削体20の掘削ビット23の詳細は、以下に説明するように構成している。なお、以下の説明では、同様の機能を有する部位については同一の符号を付して重複する説明を省略している。 The ground improvement device 1 is configured as described above, and the details of the excavation bit 23 of the excavation body 20, which is the main part of the present invention, are configured as described below. In the following description, the parts having the same function are designated by the same reference numerals, and the duplicate description is omitted.

（実施例１）
実施例１に係る掘削ビット23は、掘削体20の掘削翼体22に締結具44で着脱自在に取付けられている。これにより、掘削ビット23は、破損や摩耗などが生じた際等に容易に交換することができるようになっている。なお、掘削ビット23は、溶接等により掘削翼体22に直接取付けてもよく、掘削翼体22にホルダーを介して取付けてもよい。 (Example 1)
The drill bit 23 according to the first embodiment is detachably attached to the drill blade body 22 of the drill body 20 with a fastener 44. As a result, the excavation bit 23 can be easily replaced when it is damaged or worn. The excavation bit 23 may be directly attached to the excavation blade body 22 by welding or the like, or may be attached to the excavation blade body 22 via a holder.

掘削ビット23は、図４に示すように、掘削翼体22の前端部に前側から跨設させる上下二股状の連結部45と、その連結部45の前側に形成された刃部46とを形成している。 As shown in FIG. 4, the excavation bit 23 includes a vertically bifurcated connecting portion 45 which is provided over the front end portion of the excavating blade body 22 from the front side, and a blade portion 46 formed on the front side of the connecting portion 45. are doing.

刃部46は、図４及び図５に示すように、下側に、掘削する地盤２と接触する掘削面47と所定の逃げ角αを形成する平面状の逃げ面48を形成するとともに、上側に、掘削面47と直交する面49と所定のすくい角βを形成する平面状のすくい面50を形成している。 As shown in FIGS. 4 and 5, the blade portion 46 forms a flat flank 48 that forms a predetermined clearance angle α with the excavation surface 47 that contacts the ground 2 to be excavated on the lower side, and the upper side. Further, a plane rake face 50 forming a predetermined rake angle β is formed with a face 49 orthogonal to the excavation face 47.

逃げ面48は、進行方向（鉛直下向き）に対して左右に形成した平面状の左右逃げ面51,52と左右逃げ面51,52の間に形成した平面状の中央逃げ面53とで構成し、進行方向に傾斜状に直面する中央逃げ面53に対して左右逃げ面51,52を左右側後方へ向けて傾斜させることで、底面視や正面視で平面状の逃げ面48を進行方向に向けて凸状に形成している。なお、ここでは、左右逃げ面51,52の間に平面状の中央逃げ面53を形成しているが、これに限られず、左右逃げ面51,52を直線状の稜線で接続してもよく、また、逃げ面48の中央を角状の不連続な凸状に形成した場合に限られず、円弧状の連続な凸状に形成してもよい。 The flank face 48 is composed of planar left and right flank faces 51, 52 formed left and right with respect to the traveling direction (vertically downward) and a planar central flank face 53 formed between the left and right flank faces 51, 52. By sloping the left and right flanks 51, 52 toward the left and right sides with respect to the central flank 53 that is inclined in the traveling direction, the planar flank 48 is seen in the traveling direction in a bottom view or a front view. It is formed in a convex shape. Note that, here, although the central flank 53 is formed between the left and right flanks 51, 52, the present invention is not limited to this, and the left and right flanks 51, 52 may be connected by a straight ridge line. Also, the present invention is not limited to the case where the center of the flank 48 is formed into a corner-shaped discontinuous convex shape, and may be formed into an arc-shaped continuous convex shape.

すくい面50は、掘削方向（左水平方向）に対して左右に形成した平面状の左右すくい面54,55と左右すくい面54,55の間に形成した平面状の中央すくい面56とで構成し、掘削方向に傾斜状に直面する中央すくい面56に対して左右すくい面54,55を左右側後方へ向けて傾斜させることで、平面視や正面視で平面状のすくい面50を掘削方向に向けて凸状に形成している。なお、ここでは、左右すくい面54,55の間に平面状の中央すくい面56を形成しているが、これに限られず、左右すくい面54,55を直線状の稜線で接続してもよく、また、すくい面50の中央を角状の不連続な凸状に形成した場合に限られず、円弧状の連続な凸状に形成してもよい。 The rake face 50 is composed of a flat left and right rake face 54, 55 formed left and right with respect to the excavation direction (left horizontal direction) and a flat center rake face 56 formed between the right and left rake faces 54, 55. The left and right rake faces 54, 55 are inclined rearward with respect to the central rake face 56 that faces the digging direction in an inclined direction, so that the plane rake face 50 in the plan view or the front view is formed in the digging direction. It is formed in a convex shape toward. In addition, here, the center rake face 56 having a planar shape is formed between the left and right rake faces 54, 55, but the present invention is not limited to this, and the left and right rake faces 54, 55 may be connected by a straight ridge line. Further, the present invention is not limited to the case where the center of the rake face 50 is formed into a square discontinuous convex shape, and may be formed into a circular arc continuous convex shape.

また、刃部46は、左右逃げ面51,52と左右すくい面54,55の先端部分の間に左右側後方に向けて傾斜する平面状の左右先端面57,58を形成するとともに、左右先端面57,58と中央逃げ面53と中央すくい面56とで囲まれる中央先端面59を円弧状（円弧面）に形成することで、凸状の逃げ面48の先端と凸状のすくい面50の先端との交差部分に形成されるビット先端60を円弧面としている。なお、左右先端面57,58と中央先端面59とを滑らかに連続して接続してもよく或は角状に不連続に接続してもよく、また、中央逃げ面53及び中央すくい面56と中央先端面59とを滑らかに連続して接続してもよく或は角状に不連続に接続してもよい。 Further, the blade portion 46 forms flat left and right tip surfaces 57, 58 which are inclined rearward on the left and right sides between the tip portions of the left and right flanks 51, 52 and the right and left rake surfaces 54, 55, and the left and right tips. By forming a central tip face 59 surrounded by the faces 57, 58, the central flank 53 and the central rake face 56 in an arc shape (arc face), the tip of the convex flank face 48 and the convex rake face 50 are formed. The tip 60 of the bit formed at the intersection with the tip of is a circular arc surface. The left and right tip surfaces 57 and 58 and the central tip surface 59 may be smoothly and continuously connected or may be discontinuously connected in an angular shape, and the central flank surface 53 and the central rake surface 56 may be connected. And the central tip surface 59 may be smoothly and continuously connected, or may be discontinuously connected in a horn shape.

なお、中央逃げ面53、中央すくい面56、左右先端面57,58は、先端側から基端側に向けて同一幅で形成してもよく、これら全て又はいずれかを先端側から基端側に向けて縮幅して形成してもよい。 The central flank 53, the central rake face 56, and the left and right tip surfaces 57 and 58 may be formed with the same width from the tip side toward the base side, and all or any one of these may be formed from the tip side to the base side. It may be formed by reducing the width toward.

（実施例２）
図６に示すように、実施例２に係る掘削ビット61は、刃部46を、連結部45に連なる基端側の母材部46aと、母材部46aよりも硬質の素材によって先端側に形成した超硬部46bとで構成している。 (Example 2)
As shown in FIG. 6, in the excavating bit 61 according to the second embodiment, the blade portion 46 is provided on the tip side by the base material portion 46a on the base end side that is continuous with the connecting portion 45 and the material that is harder than the base material portion 46a. It is composed of the formed superhard portion 46b.

そして、逃げ面48の左右逃げ面51,52及び中央逃げ面53を、基端側の母材部46aに形成した左右逃げ面51a,52a及び中央逃げ面53aと先端側の超硬部46bに形成した左右逃げ面51b,52b及び中央逃げ面53bとで同一平面状に形成している。 Then, the left and right flanks 51, 52 and the central flank 53 of the flank 48, the left and right flanks 51a, 52a and the central flank 53a formed on the base material part 46a on the base end side and the cemented portion 46b on the tip side. The formed left and right flanks 51b, 52b and the central flank 53b are formed in the same plane.

また、すくい面50の左右すくい面54,55及び中央すくい面56を、基端側の母材部46aに形成した左右すくい面54a,55a及び中央すくい面56aと先端側の超硬部46bに形成した左右すくい面54b,55b及び中央すくい面56bとで同一平面状に形成している。 Further, the left and right rake faces 54, 55 and the central rake face 56 of the rake face 50 are formed on the base material portion 46a on the base end side on the left and right rake faces 54a, 55a and the center rake face 56a and the cemented carbide portion 46b on the tip side. The left and right rake faces 54b, 55b and the central rake face 56b thus formed are formed in the same plane.

これにより、実施例２に係る掘削ビット61では、逃げ面48及びすくい面50を、基端側の母材部46aと、母材部46aよりも硬質の先端側の超硬部46bとで形成している。 As a result, in the excavating bit 61 according to the second embodiment, the flank 48 and the rake face 50 are formed by the base material portion 46a on the base end side and the superhard portion 46b on the tip end side that is harder than the base material portion 46a. are doing.

（実施例３）
図７に示すように、実施例３に係る掘削ビット62は、実施例２に係る掘削ビット61と同様に、刃部46を、連結部45に連なる基端側の母材部46aと、母材部46aよりも硬質の素材によって先端側に形成した超硬部46bとで構成している。 (Example 3)
As shown in FIG. 7, in the excavating bit 62 according to the third embodiment, as in the excavating bit 61 according to the second embodiment, the blade portion 46 is connected to the base material portion 46a on the base end side connected to the connecting portion 45, and the base material portion 46a. It is composed of a super hard portion 46b formed on the tip side by a material harder than the material portion 46a.

しかも、実施例３に係る掘削ビット62では、母材部46aの先端部を上下二股状に形成するとともに、その二股状部分に超硬部46bを着脱可能に装着している。 In addition, in the excavating bit 62 according to the third embodiment, the base material portion 46a has a tip portion formed in a forked shape in the vertical direction, and the cemented carbide portion 46b is detachably attached to the forked portion.

なお、中央逃げ面53と中央すくい面56は、母材部46aに形成した中央逃げ面53aと中央すくい面56aを先端側から基端側に向けて同一幅で形成し、超硬部46bに形成した中央逃げ面53bと中央すくい面56bを先端側から基端側に向けて縮幅して形成している。 Incidentally, the central flank 53 and the central rake face 56, the central flank 53a and the central rake face 56a formed in the base material portion 46a are formed with the same width from the distal end side toward the proximal end side, and the cemented carbide portion 46b is formed. The formed central flank 53b and central rake face 56b are formed by reducing the width from the distal end side toward the proximal end side.

（実施例４）
図８に示すように、実施例４に係る掘削ビット63は、先端側のすくい面50bの左右すくい面54b,55b及び中央すくい面56bに対して基端側のすくい面50aの左右すくい面54a,55a及び中央すくい面56aを上方へ向けて起立するように傾斜させて形成することによって、すくい面50の左右すくい面54,55及び中央すくい面56を中途部で屈曲させている。 (Example 4)
As shown in FIG. 8, in the excavating bit 63 according to the fourth embodiment, the left and right rake surfaces 54b, 55b of the rake surface 50b on the tip side and the left and right rake surfaces 54a of the rake surface 50a on the base end side with respect to the central rake surface 56b. , 55a and the central rake face 56a are formed so as to be erected upward, so that the right and left rake faces 54, 55 and the central rake face 56 of the rake face 50 are bent in the middle.

なお、ここでは、母材部46aに形成したすくい面50aと超硬部46bに形成したすくい面50bとを屈曲させているが、これに限られず、超硬部46bに形成したすくい面50bを途中で屈曲させてもよく、実施例１に係る掘削ビット23のすくい面50を途中で屈曲させてもよい。 Although the rake face 50a formed on the base material portion 46a and the rake face 50b formed on the superhard portion 46b are bent here, the present invention is not limited to this, and the rake face 50b formed on the superhard portion 46b is not limited to this. The rake face 50 of the drill bit 23 according to the first embodiment may be bent halfway.

これにより、実施例４に係る掘削ビット63では、図９に示すように、先端側のすくい面50bにおいて掘削面47と直交する面49と正のすくい角βを形成するとともに、基端側のすくい面50aにおいて掘削面47と直交する面49と負のすくい角γを形成するようにしている。 As a result, in the excavating bit 63 according to the fourth embodiment, as shown in FIG. 9, a positive rake angle β is formed with the face 49 orthogonal to the excavating face 47 on the tip side rake face 50b, and at the base end side. The rake face 50a forms a negative rake angle γ with the face 49 orthogonal to the excavation face 47.

（実施例５）
実施例１〜実施例４に係る掘削ビット23,61,62,63では、ビット先端60が１個形成されているが、これに限られず、図10に示す実施例５に係る掘削ビット64のように、２以上の複数のビット先端60a,60bが形成されたものであってもよい。 (Example 5)
In the drill bits 23, 61, 62, 63 according to the first to fourth embodiments, one bit tip 60 is formed, but the present invention is not limited to this, and the drill bit 64 according to the fifth embodiment shown in FIG. As described above, two or more bit tips 60a and 60b may be formed.

なお、左右に複数のビット先端60a,60bを形成した掘削ビット64では、左右の形状が同一形状のものに限られず、左右の形状が異なる形状であってもよい。 In addition, in the excavating bit 64 in which a plurality of bit tips 60a and 60b are formed on the left and right, the left and right shapes are not limited to the same shape, and the left and right shapes may be different.

以上に説明したように、実施例１〜実施例５に係る掘削ビット23,61〜64は、回転する掘削体20に装着され、地盤２の掘削時に回転方向に向けて掘削しながら先方に向けて進行する。 As described above, the excavation bits 23, 61 to 64 according to the first to fifth embodiments are mounted on the rotating excavation body 20 and directed toward the destination while excavating in the rotation direction when excavating the ground 2. And proceed.

そして、実施例１〜実施例５に係る掘削ビット23,61〜64は、掘削面47と所定の逃げ角αを形成する平面状の逃げ面48を進行方向に向けて凸状に形成するとともに、掘削面47と直交する面49と所定のすくい角βを形成する平面状のすくい面50を掘削方向に向けて凸状に形成し、凸状の逃げ面48の先端と凸状のすくい面50の先端との交差部分に形成されるビット先端60,60a,60bを円弧面とするように構成している。 In addition, the excavating bits 23, 61 to 64 according to the first to fifth embodiments form a flat flank 48 that forms a predetermined clearance angle α with the excavation surface 47 in a convex shape in the traveling direction. The surface 49 orthogonal to the excavation surface 47 and the flat rake surface 50 forming a predetermined rake angle β are formed in a convex shape in the excavation direction, and the tip of the convex flank 48 and the convex rake surface Bit tips 60, 60a, 60b formed at intersections with the tips of 50 are configured to have an arc surface.

そのため、実施例１〜実施例５に係る掘削ビット23,61〜64では、所定の逃げ角αを形成する平面状の逃げ面48や所定のすくい角βを形成する平面状のすくい面50の作用で掘削時に掘削した地盤を後方に排出させることができ円滑な掘削を行うことができる。 Therefore, in the excavating bits 23, 61 to 64 according to the first to fifth embodiments, the flat flank 48 forming the predetermined clearance angle α and the flat rake face 50 forming the predetermined rake angle β are formed. By the action, the ground excavated at the time of excavation can be discharged backward, and smooth excavation can be performed.

しかも、実施例１〜実施例５に係る掘削ビット23,61〜64では、ビット先端60,60a,60bを円弧面状とすることで、硬質な地盤の掘削時等でもビット先端60,60a,60bの摩耗や損傷を抑制することができ、掘削性能の低下を抑制することができる。これにより、高密度の砂礫地盤や転石・巨石の混在地盤などの硬質な地盤の掘削をも行うことができる。 Moreover, in the excavating bits 23, 61 to 64 according to the first to fifth embodiments, the bit tips 60, 60a, 60b are formed into an arc surface shape, so that the bit tips 60, 60a, 60a, 60a, even when excavating hard ground. It is possible to suppress wear and damage of the 60b, and to suppress deterioration of excavation performance. As a result, it is possible to excavate hard ground such as high-density gravel ground and mixed ground of boulders and megaliths.

また、実施例１〜実施例５に係る掘削ビット23,61〜64は、逃げ面48を進行方向に対して左右に形成した平面状の左右逃げ面51,52と左右逃げ面51,52の間に形成した平面状の中央逃げ面53とで構成するとともに、すくい面50を掘削方向に対して左右に形成した平面状の左右すくい面54,55と左右すくい面54,55の間に形成した平面状の中央すくい面56とで構成し、左右逃げ面51,52と左右すくい面54,55の先端部分に平面状の左右先端面57,58を形成し、左右先端面57,58と中央逃げ面53と中央すくい面56とで囲まれる中央先端面59を円弧状のビット先端60,60a,60bとするように構成している。 In addition, the excavating bits 23, 61 to 64 according to the first to fifth embodiments are composed of the right and left flanks 51, 52 and the left and right flanks 51, 52 which are flat and have the flanks 48 formed left and right with respect to the traveling direction. It is composed of a flat central flank 53 formed in between, and the rake face 50 is formed between the left and right flat rake faces 54, 55 and the left and right rake faces 54, 55 formed left and right with respect to the excavation direction. It is composed of a flat center rake face 56, and the left and right flanks 51, 52 and the left and right rake faces 54, 55 are formed with flat left and right tip faces 57, 58. The central tip surface 59 surrounded by the central flank 53 and the central rake surface 56 is configured to be arc-shaped bit tips 60, 60a, 60b.

そのため、実施例１〜実施例５に係る掘削ビット23,61〜64では、ビット先端60,60a,60bで掘削した土砂等を中央及び左右の逃げ面51,52とすくい面54,55とに分散させることができ、掘削する地盤（掘削面47）から受ける抵抗を低減することができ、より一層円滑な掘削を行うことができる。 Therefore, in the excavating bits 23, 61 to 64 according to the first to fifth embodiments, the earth and sand excavated at the bit tips 60, 60a, 60b are used as the central and left and right flanks 51, 52 and the rake faces 54, 55. It is possible to disperse them, it is possible to reduce the resistance received from the ground to be excavated (excavation surface 47), and it is possible to perform more smooth excavation.

また、実施例１〜実施例５に係る掘削ビット23,61〜64は、中央逃げ面53及び中央すくい面56並びに左右先端面57,58を先端側から基端側に向けて縮幅するように構成している。 Further, the excavating bits 23, 61 to 64 according to the first to fifth embodiments are configured such that the central flank 53, the central rake face 56, and the left and right tip surfaces 57 and 58 are narrowed from the tip side toward the base side. Is configured.

そのため、実施例１〜実施例５に係る掘削ビット23,61〜64では、ビット先端60,60a,60bで掘削した土砂等を中央の逃げ面53とすくい面56から左右の逃げ面51,52やすくい面54,55へと良好に分散させることができ、掘削する地盤（掘削面47）から受ける抵抗をより一層低減することができる。 Therefore, in the excavating bits 23, 61 to 64 according to the first to fifth embodiments, the earth and sand excavated at the bit tips 60, 60a, 60b are flanks 51, 52 left and right from the central flank 53 and the rake face 56. It can be easily dispersed on the rough surfaces 54 and 55, and the resistance received from the ground to be excavated (excavation surface 47) can be further reduced.

また、実施例４に係る掘削ビット63は、すくい面50を屈曲させて、先端側で掘削面47と直交する面49と正のすくい角βを形成し、基端側で掘削面47と直交する面49と負のすくい角γを形成するように構成している。 Further, in the excavation bit 63 according to the fourth embodiment, the rake face 50 is bent to form a positive rake angle β with the face 49 orthogonal to the excavation face 47 on the tip side and orthogonal to the excavation face 47 on the base end side. The surface 49 is formed to form a negative rake angle γ.

そのため、実施例４に係る掘削ビット63では、強度を保持しつつ掘削する地盤（掘削面47）から受ける抵抗を低減することができる。 Therefore, in the excavating bit 63 according to the fourth embodiment, it is possible to reduce the resistance received from the excavated ground (excavation surface 47) while maintaining the strength.

また、実施例２〜実施例４に係る掘削ビット61,62,63は、逃げ面48及びすくい面50を、基端側の母材部46aと、母材部46aよりも硬質の先端側の超硬部46bとで形成するように構成している。 In addition, in the excavating bits 61, 62, 63 according to the second to fourth embodiments, the flank 48 and the rake face 50 have the base material portion 46a on the base end side and the tip end side that is harder than the base material portion 46a. It is configured to be formed with the super hard portion 46b.

そのため、実施例２〜実施例４に係る掘削ビット61,62,63では、先端側での摩耗や損傷を防止することができる。 Therefore, in the excavating bits 61, 62, 63 according to the second to fourth embodiments, wear and damage on the tip side can be prevented.

また、実施例３に係る掘削ビット62は、超硬部46bを母材部46aに着脱可能とするように構成している。 Further, the drill bit 62 according to the third embodiment is configured such that the cemented carbide portion 46b can be attached to and detached from the base material portion 46a.

そのため、実施例３に係る掘削ビット62では、超硬部46bの交換によって掘削ビット62の長寿命化を図ることができる。 Therefore, in the excavating bit 62 according to the third embodiment, it is possible to extend the life of the excavating bit 62 by replacing the cemented carbide portion 46b.

１地盤改良装置２地盤
３重機４支柱
５掘削装置６地盤改良材供給機構
７スイベルジョイント８地盤改良材貯留タンク
９水槽 10 地盤改良材混合プラント
11 地盤改良材吐出ポンプ 12 昇降支持体
13 駆動体 14 掘削軸
15 回転掘削部 16 内側軸
17 外側軸 18 駆動モータ
19 反転変速機 20 掘削体
21 撹拌翼 22 掘削翼体
23,61,62,63,64 掘削ビット 24 最内側撹拌翼
25 内側撹拌翼 26 外側撹拌翼
27 最内側撹拌翼体 28 内側撹拌翼体
29 内側撹拌翼上部片 30 内側撹拌翼中途部片
31 内側撹拌翼下部片 32 環状体
33,34,35 撹拌片 36 連結片
37 外側撹拌翼体 38 外側撹拌翼上部片
39 外側撹拌翼中途部片 40 外側撹拌翼下部片
41 環状体 42,43 撹拌片
44 締結具 45 連結部
46 刃部 46a 母材部
46b 超硬部 47 掘削面
48 逃げ面 49 面
50,50a,50b すくい面 51,51a,51b,52,52a,52b 左右逃げ面
53,53a,53b 中央逃げ面 54,54a,54b,55,55a,55b 左右すくい面
56,56a,56b 中央すくい面 57,58 左右先端面
59 中央先端面 60,60a,60b ビット先端 1 Ground improvement device 2 Ground 3 Heavy equipment 4 Support 5 Excavation device 6 Ground improvement material supply mechanism 7 Swivel joint 8 Ground improvement material storage tank 9 Water tank 10 Ground improvement material mixing plant
11 Ground improvement material discharge pump 12 Lift support
13 Drive 14 Excavation axis
15 Rotary drilling section 16 Inner shaft
17 Outer shaft 18 Drive motor
19 Reverse gearbox 20 Excavation body
21 Stirring blade 22 Excavation blade body
23,61,62,63,64 Drilling bit 24 Innermost stirring blade
25 Inner stirring blade 26 Outer stirring blade
27 Innermost stirring blade 28 Inner stirring blade
29 Upper part of inner stirring blade 30 Middle part of inner stirring blade
31 Lower part of inner stirring blade 32 Annular body
33,34,35 Stirring piece 36 Connecting piece
37 Outer stirring blade 38 Upper part of outer stirring blade
39 Middle part of outer stirring blade 40 Lower part of outer stirring blade
41 Ring 42,43 Stirrer
44 Fastener 45 Connection
46 Blade 46a Base material
46b Carbide part 47 Excavation surface
48 flank 49
50,50a, 50b Rake face 51,51a, 51b, 52,52a, 52b Left and right flank
53,53a, 53b Central flank 54,54a, 54b, 55,55a, 55b Left and right rake face
56,56a, 56b Center rake face 57,58 Left and right tip faces
59 Center tip surface 60, 60a, 60b Bit tip

Claims

In a drill bit that is attached to a rotating excavator and advances toward the destination while excavating in the direction of rotation,
A flat flank that forms a predetermined clearance angle with the excavation surface is formed in a convex shape toward the traveling direction, and a flat rake surface that forms a predetermined rake angle with the surface orthogonal to the excavation surface is the excavation direction. An excavating bit, characterized in that it is formed in a convex shape toward, and the tip of the bit formed at the intersection of the tip of the convex flank and the tip of the convex rake face is an arc surface.

The flank is composed of a planar left and right flank formed to the left and right with respect to the traveling direction and a planar central flank formed between the left and right flanks, and the rake face is left and right with respect to the excavation direction. Consists of a flat left and right rake face formed in and a flat center rake face formed between the left and right rake faces, and left and right flanks and left and right rake faces are formed with flat left and right tip faces, The drill bit according to claim 1, wherein a central tip surface surrounded by the left and right tip surfaces, a central flank surface, and a central rake surface is the arc-shaped bit tip.

The excavating bit according to claim 2, wherein the central flank surface, the central rake surface, and the left and right tip surfaces are narrowed from the tip end side toward the base end side.

The rake face is bent to form a positive rake angle with a face orthogonal to the excavation face on the tip side and form a negative rake angle with a face orthogonal to the excavation face on the base end side. The drill bit according to any one of claims 1 to 3.

The flank surface and the rake surface are formed by a base material portion on the base end side and a cemented carbide portion on the tip end side that is harder than the base material portion. Drilling bit as described.

The excavating bit according to claim 5, wherein the cemented carbide portion is detachable from the base material portion.