JP2017128920A - Drilling tool and excavation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drilling tool capable of efficiently discharging water mixed with sludge without using any vacuum pump.SOLUTION: In the drilling tool, an air supply pipe 3 for supplying compressed air is inserted into the inner periphery of an excavation pipe P1 on the front end of which a tool body 1 is disposed. On the outer periphery of the excavation pipe P1, a water supply line F is formed for supplying excavation water to the front end of the tool body 1. On the front end of the tool body 1, in a space E between the excavation pipe P1 and the air supply pipe P3, a discharge exhaust passage 7 is formed for discharging sludge generated during drilling together with the excavation water supplied from the water supply line F. On the front end of the air supply pipe P3, an exhaust hole 17A opened to the space E is formed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an excavation tool used in a reverse circulation method for taking in flour generated during excavation into a tool body and discharging it through an excavation pipe, and an excavation method using the excavation tool.

  In the foundation pile driving method using a casing pipe, the compressed air used to strike the drill bit (tool body) is generally ejected from the tip of the drill bit, and the bedrock is crushed during the excavation. A certain flour is discharged to the rear end side by the compressed air through the space between the casing pipe and the excavating rod. However, when such a construction method is implemented in urban areas, the compressed air ejected from the tip of the excavation bit may leak into the rock surrounding the excavation hole and reduce the strength, and in some cases, the surrounding rock may collapse. is there.

  In such a case, it is effective to prevent the compressed air from leaking by supplying muddy water mixed with bentonite to the drilling hole, but it is necessary to discharge the flour that is mixed with muddy water with high specific gravity. For this reason, the pressure of the compressed air to be ejected must also be increased. Therefore, as an excavation tool used for such a construction method, for example, Patent Document 1 supplies fresh water as carrier water through the casing pipe, and sucks and discharges the flour that is mixed with the carrier water by a vacuum pump. Things have been proposed.

Japanese Patent Laid-Open No. 2007-170087

  However, in such an excavation tool described in Patent Document 1, not only a vacuum pump is required, but also the conveying water mixed with the flour passes through the vacuum pump. There is a risk that damage will occur early, making it difficult to perform stable excavation over a long period of time.

  The present invention has been made under such a background. An excavation tool capable of efficiently discharging water mixed with flour without using a vacuum pump, and excavation using the excavation tool. The purpose is to provide construction methods.

  In order to solve the above problems and achieve such an object, the excavation tool of the present invention has an air supply pipe for supplying compressed air to the inner periphery of the excavation pipe in which the tool body is disposed at the tip. In addition, the outer periphery of the excavation pipe is provided with a water supply channel for supplying excavation water to the tip of the tool body, and the tip of the tool body is fed with the flour generated during excavation. A discharge passage is formed in the space between the drilling pipe and the air supply pipe together with the drilling water supplied from the water supply passage, and an exhaust hole opening in the space is formed at the tip of the air supply pipe. It is formed.

  Further, the excavation method of the present invention uses such an excavation tool to supply excavation water to the tip of the tool main body through the water supply channel while forming a excavation hole by the tool main body. The generated dust is discharged together with the drilling water through the discharge passage to a space between the drilling pipe and the air supply pipe, and the dust and drilling water discharged to the space are exhausted from the exhaust hole. The compressed air is discharged to the rear end side.

  In the excavation tool having the above-described configuration and the excavation method using the excavation tool, an exhaust hole opening in a space between the excavation pipe is formed at the tip of the air supply pipe. The compressed air used to strike the tool body is supplied to the air supply pipe, exhausted from the exhaust hole, and the dust and drilling water discharged into the space between the drilling pipe and the air supply pipe are discharged into the exhaust pipe. The compressed air exhausted from the hole is pushed out to the rear end side and discharged.

  Therefore, according to such an excavation tool and excavation method, the supplied compressed air for imparting a striking force to the tool body can be used for the dusting and the discharge of the excavation water, and at the time of excavation, the excavation water is supplied via the water supply channel Is supplied to the tip of the tool main body, it is possible to prevent the compressed air from leaking into the rock around the excavation hole and reducing the strength, thereby causing collapse. Moreover, since drilling water is supplied to the front-end | tip part of a tool main body via a water supply channel, fresh water can be used and it is not necessary to make the pressure of compressed air higher than necessary.

  And since the flour and the drilling water can be discharged to the rear end side of the space between the drilling pipe and the air supply pipe using the compressed air in this way, the vacuum pump is not required. There is no damage caused by passing the flour inside. Also, when compressed air is exhausted and dusting and drilling water are pushed out to the rear end side, the space on the tip side from the exhaust hole becomes negative pressure. And the drilling water can be sucked and discharged continuously.

  Here, by forming the exhaust hole so as to be inclined toward the rear end side toward the outer peripheral side of the tool main body and open to the space, the dust and the drilling water discharged into the space are formed. Can be pushed out to the rear end side and discharged more reliably. Furthermore, when the excavation tool having the above configuration is applied to a foundation pile driving method using a casing pipe, the casing pipe is used as a water supply pipe, and the excavation pipe is inserted into the inner periphery of the water supply pipe, thereby A water supply channel can be formed between the water supply pipe and the excavation pipe. Therefore, it is possible to reliably supply the drilling water to the tip of the tool body.

  Further, particularly when the excavation pipe is inserted using the casing pipe as a water supply pipe, a plurality of groove portions extending from the front end of the tool body to the rear end side are formed on the outer periphery of the front end of the tool body. Among the groove portions of the strip, some of the groove portions are communicated with the water supply channel, and the remaining groove portions are communicated with the discharge channel, and the tip portions of the some groove portions and the tip portions of the remaining groove portions are By communicating through the communication groove formed on the tip surface of the tool body, the flour is efficiently discharged while the drilling water supplied from a part of the groove flows into the tip of the remaining groove through the communication groove. And can be discharged from the discharge path to the space between the excavation pipe and the air supply pipe.

  On the other hand, on the outer periphery of the tip of the tool body, a groove extending from the tip of the tool body to the rear end side and communicating with the water supply channel is formed, and in the tool body on the inner peripheral side of the groove, A hole extending from the front end of the tool body toward the rear end is formed as the discharge path, and the front end of the groove and the front end of the hole are connected via a communication groove formed on the front end surface of the tool body. Similarly, the ground dust can be efficiently collected while the drilling water supplied from the groove flows into the tip of the hole through the communication groove.

  As described above, according to the present invention, the strength of the rock around the excavation hole is not reduced, and collapse is not caused, and the pressure of the compressed air does not need to be increased more than necessary, and a vacuum pump is required. Therefore, stable excavation can be efficiently performed at low cost.

It is a sectional side view which shows 1st Embodiment of the excavation tool of this invention. It is a front view of the tool main body of embodiment shown in FIG. It is a rear view of the shank part in the tool main body of embodiment shown in FIG. It is ZZ sectional drawing in FIG. It is a sectional side view which shows 2nd Embodiment of the excavation tool of this invention. It is a front view of the tool main body of embodiment shown in FIG. It is a rear view of the shank part in the tool main body of embodiment shown in FIG. It is ZZ sectional drawing in FIG.

  1 to 4 show a first embodiment of an excavation tool of the present invention. In the present embodiment, the tool body 1 is formed of a metal material such as a steel material, and has a substantially multi-stage cylindrical shape with a bottom centered on an axis O whose front end side in the axis O direction (left side in FIG. 1) has a one-step large diameter. Of the pilot bit 2 and a ring bit 3 formed in an annular shape or a cylindrical shape around the axis O by a metal material such as steel that is detachably attached to the outer periphery of the tip end portion of the pilot bit 2. . The rear end portion of the pilot bit 2 having a small diameter is a shank portion 2A having a male screw portion formed on the outer periphery, and a cylindrical excavation pipe P1 is attached to the shank portion 2A, and the pilot bit is passed through the excavation pipe P1. 2 is given a rotational force around the axis O and a thrust and striking force toward the front end side in the direction of the axis O.

  In the present embodiment, the tip portion of the pilot bit 2 on the tip side of the shank portion 2A is formed so as to reduce in diameter to approximately three steps toward the tip side. Among these, the conical pilot bit side contact with the axis O gradually decreasing in diameter toward the tip end in the direction of the axis O is provided between the rearmost large diameter portion 2B and the next medium diameter portion 2C. A pilot bit having a conical surface centered on an axis O that gradually decreases in diameter toward the tip side in the direction of the axis O, between the medium diameter portion 2C and the most advanced small diameter portion 2D. A side contact surface 5 is formed.

  Here, in the cross section along the axis O as shown in FIG. 1, the pilot bit side contact surface 5 is closer to the axis O than the inclination angle α formed by the pilot bit side contact surface 4 with respect to the axis O. In contrast, the inclination angle β is small. In the present embodiment, as shown in FIG. 1, the pilot bit side contact surface 4 has a length A in the direction parallel to the axis O when the length A is directed to the tip side in the direction of the axis O by this length A. In other words, the pilot bit side contact surface 5 is formed so that the radius B of the diameter decreases or less, that is, the inclination angle α formed with respect to the axis O is 45 ° or more. The length C in the direction parallel to the axis O is formed so as to be longer than the radius D of which the diameter is reduced when the length C is directed to the front end side in the axis O direction. The inclination angle β is less than 45 °.

  The length C of the pilot bit side contact surface 5 is sufficiently longer than the length B of the pilot bit side contact surface 4, and the radius D of the pilot bit side contact surface 5 is equal to the pilot bit side contact surface 5. It is set to be slightly larger than the radius B of the surface 4. The outer peripheral surfaces of the large-diameter portion 2B, the medium-diameter portion 2C, and the small-diameter portion 2D are cylindrical surfaces having a constant outer diameter centered on the axis O, and of these, the axis O of the medium-diameter portion 2C. The length in the direction is set slightly longer than the large diameter portion 2B and the small diameter portion 2D.

  Further, on the outer periphery of the front end portion of the pilot bit 2, a plurality of grooves 6 (three in the present embodiment) are formed at substantially equal intervals in the circumferential direction extending from the front end surface to the rear end side. Among the plurality of groove portions 6, a part of the groove portions (one groove portion on the upper side in FIG. 1 and one groove on the left side in FIG. 2) 6 </ b> A penetrates from the front end surface of the pilot bit 2 to the rear end surface of the large diameter portion 2 </ b> B. The remaining groove 6B extends from the front end surface of the pilot bit 2 to the front of the large-diameter portion 2B and cuts to the outer peripheral side, and from the rear end where the remaining groove 6B is cut off, As the discharge path 7 in the embodiment, a hole having a circular cross section toward the rear end side is formed toward the inner peripheral side, and opens to the inner peripheral part of the bottomed cylindrical pilot bit 2.

  Further, a communication groove 8 is formed on the front end surface of the pilot bit 2 so as to connect the front end of the partial groove 6A and the front end of the remaining groove 6B. In this embodiment, the communication groove 8 extends from the front end of a part of the groove 6A in the radial direction with respect to the axis O to the front of the axis O as shown in FIG. It is formed in a Y-shape that reaches the leading ends of the two remaining grooves 6B while branching and curving in two without reaching. The groove 6 has a substantially square or U-shaped cross section, and the bottom surface 4A facing the outer peripheral side is slightly inclined toward the outer peripheral side toward the rear end side as shown in FIG. As shown in FIG. 4, the communication groove 8 has a U-shaped cross section and extends on a plane perpendicular to the axis O.

  Further, on the front end surface of the pilot bit 2, except for the opening portion of the groove portion 6 and the communication groove 8, a central face surface that is perpendicular to the axis O and toward the outer peripheral side toward the rear end side. Thus, a conical surface-shaped outer peripheral gauge surface is formed. On these face surface and gauge surface, an excavation tip 9 made of cemented carbide harder than the pilot bit 2 is implanted perpendicularly to the face surface and gauge surface so as to avoid the opening of the groove portion 6 and the communication groove 8. It is installed.

  Furthermore, on the outer peripheral surface of the small-diameter portion 2D of the pilot bit 2, an arc plate-shaped ridge portion 2E centering on the axis O protruding to the outer peripheral side is slightly located from the pilot bit side contact surface 5 to the tip side. A plurality of strips (three strips in this embodiment) are formed at equal intervals in the circumferential direction at positions spaced apart. In the present embodiment, these protrusions 2E extend from one end in the circumferential direction of the groove 6 (the end in the counterclockwise direction when viewed from the front as shown in FIG. 1). It is planted over the ridge 2E.

  In the annular or cylindrical ring bit 3 attached to the outer periphery of the pilot bit 2, the axial line O is gradually reduced in diameter toward the front end side in the axis O direction on the inner peripheral surface of the rear end portion. A conical ring-shaped ring bit side contact surface 10 is formed. The ring bit side contact surface 10 has an inclination angle β equal to the pilot bit side contact surface 5 with respect to the axis O in a cross section along the axis O.

  That is, the ring bit side contact surface 10 has a radius that decreases when the length C in the direction parallel to the axis O is the same as the pilot bit side contact surface 5 toward the tip side in the axis O direction by this length C. It is formed so as to be longer than D, and is formed at an inclination angle β of less than 45 ° with respect to the axis O. 1, the ring bit side contact surface 10 is brought into close contact with the pilot bit side contact surface 5 as shown in FIG. 1, and the pilot bit side contact surface 5 extends from the front end surface of the pilot bit 2 in the axis O direction. Installed over the rear edge.

  Further, the inner peripheral surface of the tip portion of the ring bit 3 has a slightly larger inner diameter than the small-diameter portion 2D of the pilot bit 2, and the projecting portion of the pilot bit 2 is formed on the inner peripheral surface of the tip portion. The groove 3A, which is slightly wider in the circumferential direction than 2E, penetrates from the tip surface of the ring bit 3 toward the ring bit side contact surface 10 in the direction of the axis O in the same number as the ridges 2E in the circumferential direction. It is formed to do.

  Further, from one end in the circumferential direction of the recessed groove portion 3A (the end portion in the same direction as the end portion where the projecting ridge portion 2E of the pilot bit 2 extends in the circumferential direction from the groove portion 6), the radial depth is different from that of the recessed groove portion 3A. An engagement portion 3B having an L-shaped cross section that is slightly longer in the direction of the axis O than the protrusion 2E is formed. The ring bit 3 is piloted by accommodating the protrusion 2E in the groove 3A. By inserting the pilot bit 2 from the distal end side of the distal end of the bit 2 and rotating the pilot bit 2 toward one end side in the circumferential direction, the protruding portion 2E is fitted into the engaging portion 3B and can be engaged. Therefore, the position of the groove portion 6 of the pilot bit 2 coincides with the concave groove portion 3A of the ring bit 3 in the circumferential direction in a state where the protruding portion 2E is fitted to the engaging portion 3B.

  Furthermore, the front end surface of the ring bit 3 also includes an inner peripheral face surface perpendicular to the axis O, and an outer peripheral gauge surface that is inclined toward the outer peripheral side toward the rear end side. Drilling tips 9 made of a cemented carbide harder than the ring bit 3 are vertically implanted on the face surface and the gauge surface. A concave groove 3 </ b> C is formed on the outer peripheral surface of the tip of the ring bit 3 between the excavation tips 9 planted on the gauge surface.

  On the other hand, the outer peripheral surface of the ring bit 3 has a rectangular shape with a cross section along the axis O extending in the axis O direction at a position spaced from the gauge surface and the rear end surface of the front end surface in the axis O direction. A ring bit side locking groove 11 opened to the outer peripheral side is formed over the entire periphery. Further, the outer peripheral portion of the ring bit 3 on the rear end side of the ring bit side locking groove 11 is an annular ring bit side locking portion 12 that protrudes toward the outer peripheral side with respect to the ring bit side locking groove 11. The outer diameter of the ring bit 3 is smaller than that of the tip of the ring bit 3, and the length in the direction of the axis O is set shorter than that of the ring bit side locking groove 11. Note that the outer peripheral portion of the rear end of the ring bit side locking portion 12 is chamfered.

  Further, in the present embodiment, a cylindrical casing pipe 13 centering on the axis O is disposed as the water supply pipe P2 in the present embodiment on the outer periphery of the pilot bit 2 to which the ring bit 3 is attached as described above. A water supply path F is formed between the casing pipe 13 (water supply pipe P2) on the outer periphery of the excavation pipe P1. The casing pipe 13 is formed by integrally joining a cylindrical casing top 13B centered on the axis O by welding or the like to the tip of a cylindrical pipe body 13A centering on the axis O, The pipe main body 13A has an inner diameter larger than the outer diameter of the large diameter portion 2B of the pilot bit 2, and a plurality of pipe main bodies 13A are sequentially added to the rear end side by welding or the like according to the depth of the drilling hole. Go.

  The casing top 13B is formed so that the outer diameter of the rear end portion thereof is one step smaller than that of the tip end portion, and the tip end portion of the most advanced pipe body 13A is fitted and joined to the stepped portion. Further, the inner diameter of the rear end portion of the casing top 13B is set to be slightly smaller than the outer diameter of the large diameter portion 2B of the pilot bit 2 and slightly larger than the outer diameter of the medium diameter portion 2C. A casing pipe that can be brought into contact with the pilot bit side contact surface 4 formed on the rear end side of the pilot bit side contact surface 5 of the pilot bit 2 on the inner peripheral portion of the rear end surface of the casing top 13B. A side contact surface 14 is formed.

  That is, the casing pipe side contact surface 14 is also formed in a conical surface shape with the axis O gradually decreasing in diameter toward the tip end side in the axis O direction, and along the axis O as shown in FIG. In the cross section, the inclination angle α formed with respect to the axis O is equal to the inclination angle α of the pilot bit side contact surface 4 and larger than the inclination angle β formed between the pilot bit side contact surface 5 and the ring bit side contact surface 10. It is an angle. Furthermore, in this embodiment, when the length A in the direction parallel to the axis O in the cross section along the axis O of the casing pipe side contact surface 14 is directed to the tip side in the axis O direction by this length A. The inclination angle α is set to 45 ° or more.

  Further, the outer diameter of the tip portion of the casing top 13B is set equal to the outer diameter of the pipe body 13A, and is set smaller than the outer diameter of the tip portion that is the maximum outer diameter of the ring bit 3. A casing pipe-side locking groove 15 that opens inward on the inner peripheral side of the casing top 13 </ b> B in a rectangular shape with a cross section along the axis O extending in the direction of the axis O in order toward the tip. A casing pipe side latching portion 16 that protrudes inward from the casing pipe side latching groove 15 is formed over the entire circumference.

  The casing pipe side locking groove 15 and the casing pipe side locking portion 16 are set to have the same length in the direction of the axis O as the ring bit side locking groove 11 and the ring bit side locking portion 12, respectively. The inner diameter of the stop groove 15 is set to be slightly larger than the outer diameter of the ring bit side locking portion 12. The inner diameter of the casing pipe side locking portion 16 is set to be slightly larger than the outer diameter of the ring bit side locking groove 11 and smaller than the outer diameter of the ring bit side locking portion 12, Has been chamfered.

  In such a casing top 13B, the ring bit 3 accommodates the casing pipe side latching portion 16 in the ring bit side latching groove 11 and the ring bit side latching portion 12 in the casing pipe side latching groove 15. Is housed in the axis O, and is also locked to the front and rear ends in the direction of the axis O in a range in which the ring bit side locking groove 11 and the casing pipe side locking groove 15 are formed. It is attached.

  In order to attach the ring bit 3 to the casing top 13B in this way, for example, the chamfered portions of the rear end outer peripheral portion of the ring bit side locking portion 12 and the front end inner peripheral portion of the casing pipe side locking portion 16 are mutually connected. After matching, by pressing at least one of the casing top 13B and the ring bit 3 in the direction of the axis O, the rear end of the ring bit 3 is elastically reduced in diameter and the tip of the casing top 13B is elastic. The casing pipe side latching portion 16 may be accommodated in the ring bit side latching groove 11 and the ring bit side latching portion 12 may be accommodated in the casing pipe side latching groove 15. After the ring bit 3 is attached in this way, the casing top 13B is joined to the pipe body 13A, and the ring bit 3 is disposed at the tip of the casing pipe 13.

  After arranging the ring bit 3 on the casing top 13B at the front end of the casing pipe 13 in this way, the pilot bit 2 attached to the front end of the excavation pipe P1 is inserted into the casing pipe 13 from the rear end side, and As described above, the protrusion 2E is accommodated in the concave groove 3A, and then the pilot bit 2 is rotated to one end side in the circumferential direction, so that the protrusion 2E is fitted and engaged with the engaging portion 3B. The excavation pipe P1 is also added and connected sequentially according to the depth of the excavation hole, and the excavation pipe P1 at the end is connected to the excavator. The pilot bit 2 thus inserted into the casing pipe 13 is positioned when the pilot bit side contact surface 4 contacts the casing pipe side contact surface 14 of the casing top 13B.

  Further, from this state, the tip portions of the pilot bit 2 and the ring bit 3 are brought into contact with the bedrock and the like, and the rotational force around the axis O and the tip side in the axis O direction from the excavator to the pilot bit 2 via the excavation pipe P1. When excavation is performed by applying thrust and striking force to the ring, the ring bit 3 is pressed against the rear end side by resistance from the rock or the like, and the ring bit side contact surface 10 comes into close contact with the pilot bit side contact surface 5. The ring bit 3 may be pressed to the rear end side before excavation so that the ring bit side contact surface 10 is in close contact with the pilot bit side contact surface 5.

  Here, in the ring bit side latching portion 12 and the casing pipe side latching portion 16, the pilot bit side contact surface 4 is in contact with the casing pipe side contact surface 14 and the ring bit side contact surface 10 is in contact with the pilot bit. As shown in FIG. 1, the casing pipe side locking groove 15 and the ring bit side locking groove 11 are disposed at positions spaced from both ends in the axis O direction in close contact with the side contact surface 5. It is formed as follows.

  An air supply pipe P3 is inserted into the inner periphery of the cylindrical excavation pipe P1 from the rear end side, and its tip is inserted into the inner periphery of the pilot bit 2 in the tool body 1. An exhaust plug 17 is attached to the distal end portion of the air pipe P3 and is accommodated in the inner peripheral portion of the pilot bit 2. The air supply pipe P3 is formed in a cylindrical shape centering on an axis O having an outer diameter smaller than the inner diameter of the excavation pipe P1, and a space having an annular cross section is formed between the air supply pipe P3 and the excavation pipe P1. E is formed. Compressed air used to drive the air hammer when applying a striking force to the pilot bit 2 as described above is supplied to the inner peripheral portion of the air supply pipe P3, for example.

  The exhaust plug 17 is formed in a bottomed multistage cylindrical shape, and a male screw portion screwed into the inner periphery of the tip end portion of the air supply pipe P3 is formed on the outer periphery of the rear end portion of the small diameter, and the large diameter tip portion is a pilot bit. It is set as the outer diameter which can be fitted in the inner peripheral part of 2 with a slight space | interval. In addition, the rear end surface of the front end portion is formed in a conical surface shape toward the rear end side toward the inner peripheral side, and the inclination angle of the pilot bit 2 toward the rear end side similarly toward the inner peripheral side. 7 is set equal to the inclination angle. Such an exhaust plug 17 is attached to the front end portion of the air supply pipe P3 and inserted into the inner peripheral portion of the pilot bit 2, and as shown in FIG. It arrange | positions so that it may be located in the opening part front-end edge of the discharge path 7 in the bit 2 inner peripheral part.

  The inner peripheral portion of the bottomed cylindrical exhaust plug 17 communicates with the inner peripheral portion of the cylindrical air supply pipe P3, and the rear end surface of the exhaust plug 17 is closer to the rear end side than the rear end surface of the front end portion. On the outer peripheral surface, a plurality (three) of exhaust holes 17A that open to the space E are formed at equal intervals in the circumferential direction in the present embodiment. The exhaust hole 17 </ b> A of the present embodiment is inclined so as to go to the rear end side as going to the outer peripheral side of the tool body 1. An exhaust hole 17B having a smaller diameter than the exhaust hole 17A is also formed from the inner peripheral portion of the exhaust plug 17 to the distal end surface of the exhaust plug 17 perpendicular to the axis O.

  In one embodiment of the excavation method of the present invention in which excavation is performed with such an excavation tool, the striking force and thrust to the front end side in the direction of the axis O applied to the pilot bit 2 from the excavator through the excavation pipe P1 are the casing. The pipe 13 is transmitted from the pilot bit side contact surface 4 to the casing pipe side contact surface 14 of the casing top 13B, and the ring bit 3 is transmitted from the pilot bit side contact surface 5 to the ring bit side contact surface 10. A drilling hole is formed by the drilling tip 9 planted on the front end surfaces of the pilot bit 2 and the ring bit 3, and a casing pipe 13 is inserted into the drilling hole. The rotational force about the axis O applied to the pilot bit 2 is also transmitted from the pilot bit side contact surface 5 to the ring bit 3 via the ring bit side contact surface 10.

  In addition, at the same time when the excavation hole is formed in this way, excavation water is supplied from the rear end side to the water supply path F between the excavation pipe P1 and the casing pipe 13 which is the water supply pipe P2. The drilling water in this embodiment is fresh water such as tap water, and the drilling water supplied in this way is the bottom of the drilling hole from the partial groove 6A of the pilot bit 2 opened at the tip of the water supply channel F in this embodiment. To the bottom, fills the bottom, reaches the remaining groove 6B while flowing in the communicating groove 8 communicated with the tip of this part of the groove 6A while winding the flour as the pilot bit 2 rotates. It passes through the discharge passage 7 communicating with the groove 6B and flows into the space E on the rear end side of the rear end surface of the front end portion of the exhaust plug 17 on the inner periphery of the pilot bit 2 and is filled from the exhaust hole 17A to the rear end side. .

  Then, in this way, the drilling water mixed with the flour filled up to the rear end side of the exhaust hole 17A has the compressed air supplied into the air supply pipe P3 from the inner periphery of the exhaust plug 17 through the exhaust hole 17A. As it is ejected, it is sent to the rear end side and discharged. Further, since the tip of the space E from which the drilling water has been discharged becomes negative pressure, the drilling water remaining in the discharge channel 7 from the remaining groove 6B is sucked together with the flour by the tip of the space E, and exhausted. The air is continuously discharged by the jet of compressed air from the hole 17A.

  Thus, according to the excavation tool and excavation method having the above-described configuration, the compressed air for applying the striking force to the pilot bit 2 and the ring bit 3 of the tool body 1 as described above without requiring a vacuum pump or the like. It is possible to discharge drilling water mixed with flour. The excavated water to be discharged passes through the space E between the excavated pipe P1 and the air supply pipe P3. Therefore, even if dusting is mixed, the discharge is not hindered. For this reason, it is possible to achieve stable and efficient low-cost excavation and dust discharge over a long period of time.

  Moreover, since the compressed air for giving a striking force is used for discharging drilling water that is exhausted toward the rear end side in the space E and mixed with dust, it does not leak around the drill hole, Moreover, since the bottom of the excavation hole is filled with excavation water, the surrounding rock mass does not collapse due to strength reduction. Furthermore, since the drilling water is also supplied through the water supply path F between the drill pipe P1 and the casing pipe 13 which is the water supply pipe P2, the above-described fresh water having a lower specific gravity than muddy water or the like can be used as the drilling water. The compressed air ejected from the exhaust hole 17A is not required to have a pressure higher than necessary.

  Further, in the present embodiment, the exhaust hole 17A is inclined so as to go to the rear end side as it goes to the outer peripheral side of the tool body 1, so that the dust in the space E is compressed by the compressed air exhausted from the exhaust hole 17A. Drilling water can be more reliably discharged to the rear end side. Further, in the present embodiment, the excavation pipe P1 is inserted into the casing pipe 13 as the water supply pipe P2, and the water supply path F is between the excavation pipe P1 and the casing pipe 13 (water supply pipe P2). It is formed and can be applied to a foundation pile driving method in which the casing pipe 13 is built in the excavation hole while forming the excavation hole. For this reason, it becomes possible to supply the drilling water to the bottom of the drilling hole at the tip of the tool body 1 and discharge the dust while preventing the drilling hole itself from collapsing.

  In addition, in this embodiment, in addition to supplying the drilling pipe P1 into the casing pipe 13 and supplying the drilling water to the water supply path F therebetween, in this embodiment, the tool body attached to the tip of the drilling pipe P1. A plurality of groove portions 6 extending from the front end surface to the rear end side are formed on the outer periphery of the front end portion of one pilot bit 2 at intervals in the circumferential direction, and some of the groove portions 6A communicate with the water supply path F. At the same time, the remaining groove 6 </ b> B communicates with the space E through which the drilling water is discharged via the discharge path 7. The tip portions of some of the groove portions 6A and the remaining groove portions 6B communicate with each other through the communication groove 8 formed on the tip surface of the pilot bit 2, so that the tip portions of the pilot bit 2 and the ring bit 3 are planted. The flour produced by the provided excavation tip 9 can be uniformly taken into the communication groove 8 and reliably discharged together with the excavation water.

  Further, in this embodiment, the pilot bit 2 and the ring bit 3 are configured to rotate integrally around the axis O by the close contact between the conical pilot bit side contact surface 5 and the ring bit side contact surface 10. ing. For this reason, between the pilot bit 2 and the ring bit 3, the drilling water is supplied to the drilling hole from a part other than the part of the groove part 6A, or the flour is contained from a part other than the remaining groove part 6B. It is possible to prevent the drilling water from being discharged, and it is possible to discharge the drilling water including the flour that has been taken in by the communication groove 8 as described above more reliably.

  In the first embodiment, among the plurality of grooves 6 formed on the outer periphery of the front end of the pilot bit 2 as described above, the front ends of some of the grooves 6A communicating with the water supply path F and the discharge path 7 are provided. The tip of the remaining groove 6B that communicates with the space E via the communication groove 8 is communicated by the communication groove 8, but the pilot bit 2 of the tool body 1 as in the second embodiment shown in FIGS. A hole 18 may be formed as the discharge path 7 on the inner peripheral side of the groove 6 on the outer periphery of the tip, and the hole 18 and the tip of the groove 6 may be communicated by the communication groove 19. 5 to 8, the same reference numerals are assigned to the same parts as those of the first embodiment shown in FIGS. 1 to 4, and description thereof is omitted.

  That is, in this second embodiment, the plurality of grooves 6 (three also in this embodiment) formed on the outer periphery of the tip end portion of the pilot bit 2 are all the same as some of the grooves 6A of the first embodiment. The pilot bit 2 is opened to the rear end surface of the pilot bit 2 and communicates with the water supply path F between the excavation pipe P1 and the casing pipe 13 (water supply pipe P2). On the other hand, the hole 18 having a circular cross section penetrating from the tip surface of the pilot bit 2 to the inner peripheral portion of the pilot bit 2 is formed at a position away from the axis O on the inner peripheral side of each groove portion 6. ing.

  The tip of the hole 18 and the tip of the groove 6 communicate with each other on a plane perpendicular to the axis O via a communication groove 19 that extends radially in the radial direction with respect to the axis O. Further, the large-diameter distal end portion of the exhaust plug 17 accommodated in the inner peripheral portion of the pilot bit 2 has a plurality of (three) notches 17C penetrating the outer periphery of the distal end portion in the direction of the axis O in the circumferential direction. Each is formed between the exhaust holes 17A.

  Also in the second embodiment, the cutting water supplied from the water supply path F flows to the tip end side of the pilot bit 2 of the tool body 1 through each groove portion 6, and then flours while flowing through the communication groove 19. It winds up and reaches the tip of the hole 18, flows from the hole 18 into the inner peripheral portion of the pilot bit 2, and is filled from the notch 17 </ b> C to the rear end side from the exhaust hole 17 </ b> A of the exhaust plug 17. Then, the compressed air is exhausted from the exhaust hole 17A, so that the cutting water mixed with the dust is pushed and discharged to the rear end side, and the drilling water mixed with the new dust is discharged from the hole 18. Sucked.

  As described above, the excavation tool of the second embodiment and the excavation method using the excavation tool do not require a vacuum pump or the like as in the first embodiment, and may require high pressure to the compressed air. In addition, it is possible to perform stable, efficient and low-cost excavation while preventing the surrounding rock mass from collapsing. In the second embodiment, more cutting water can be supplied to the distal end side of the tool body 1 even if the number of grooves 6 formed in the distal end portion of the pilot bit 2 is the same as that in the first embodiment. In addition, since the distance that the milling water is involved and the cutting water flows through the communication groove 19 is short, it is also suitable for excavation at high speed.

DESCRIPTION OF SYMBOLS 1 Tool main body 2 Pilot bit 3 Ring bit 4 Pilot bit side contact surface 5 Pilot bit side contact surface 6 Groove part 6A Some groove parts 6B Remaining groove part 7 Discharge path 8, 19 Communication groove 9 Excavation tip 10 Ring bit side contact surface 13 Casing pipe 14 Casing pipe side contact surface 17 Exhaust plug 17A Exhaust hole 17C Notch 18 Hole (discharge path)
P1 Excavation pipe P2 Water supply pipe P3 Air supply pipe O Axis line of tool body 1 F Water supply path E Space between excavation pipe P1 and air supply pipe P3

Claims (6)

An air supply pipe that supplies compressed air is inserted into the inner periphery of the drilling pipe in which the tool body is disposed at the tip, and drilling water is supplied to the tip of the tool body at the outer periphery of the drilling pipe. There is a water supply channel,
The tip of the tool body is formed with a discharge path that discharges the flour generated during excavation into the space between the drilling pipe and the air supply pipe together with the drilling water supplied from the water supply path,
An excavation tool characterized in that an exhaust hole opening in the space is formed at a tip of the air supply pipe.   2. The excavation tool according to claim 1, wherein the exhaust hole is inclined to open toward the rear end side toward the outer peripheral side of the tool main body and opens in the space.   The excavation pipe according to claim 1 or 2, wherein the excavation pipe is inserted into an inner periphery of the water supply pipe, and the water supply path is formed between the water supply pipe and the excavation pipe. tool. On the outer periphery of the tip end of the tool body, a plurality of grooves extending from the tip end of the tool body to the rear end side are formed,
Among these multiple grooves, some of the grooves communicate with the water supply channel, and the remaining grooves communicate with the discharge channel.
The tip part of the said some groove part and the tip part of the said remaining groove part are connected via the communication groove formed in the front end surface of the said tool main body, The Claims 1-3 characterized by the above-mentioned. The excavation tool as described in any one of these. On the outer periphery of the tip of the tool body, a groove is formed extending from the tip of the tool body to the rear end side and communicating with the water supply channel.
A hole extending from the front end of the tool main body to the rear end side is formed as the discharge path in the tool main body on the inner peripheral side of the groove,
The tip part of the said groove part and the tip part of the said hole part are connected via the communication groove formed in the front end surface of the said tool main body, The any one of Claims 1-3 characterized by the above-mentioned. The excavation tool according to one item. Using the excavation tool according to any one of claims 1 to 5,
While forming a drilling hole with the tool body, supply drilling water to the tip of the tool body through the water supply channel,
The dust produced during excavation is discharged into the space between the excavation pipe and the air supply pipe through the discharge passage together with the excavation water,
The excavation method characterized in that the dust and the drilling water discharged into the space are discharged to the rear end side by compressed air exhausted from the exhaust hole.

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