JP2019132039A - Conical bit - Google Patents

Abstract

To prevent a drilling chip at the tip of a conical bit from quickly unsymmetrically wearing (one-side wear).SOLUTION: A conical bit (45) in this invention which is fitted rotatably and in a detachable manner to a holder (46) mounted on a drilling head (20) comprises a bit body part (47) with an excavation chip (51) attached on its tip, an installation shank (48) which is rotatably supported with the holder (46), and an anti-stick means to prevent the installation shank (48) from sticking to the holder (46) causing an unrotatable state. For example, the anti-stick means includes providing a seal member (55) on the tip side of a connector (53) fitted between the holder (46) and the installation shank (48) and preventing the installation shank (48) from becoming unrotatable as a result of sticking to the holder (46) due to intrusion of the sediment excavated by the bit body part (47) into the connector (53) fitted between the holder (46) and the installation shank (48).SELECTED DRAWING: Figure 5

Description

  The present invention relates to a conical bit that is detachably and rotatably attached to a holder provided in an excavation head.

  2. Description of the Related Art Conventionally, excavation apparatuses that excavate the ground are provided with an excavation head for excavating the ground at the lower end of the rotating shaft. In this excavation head, a horizontal wing shape or a spiral wing shape excavation blade is provided at the lower end of the rotary shaft, and an excavation bit is provided on the excavation blade.

  As the excavation bit provided in the excavation head, a conical bit that is detachably and rotatably attached to a holder provided on the excavation blade is widely used (for example, see Patent Document 1).

  The conical bit has a cylindrical mounting shaft portion on the base end side of the bit body provided with a hard drilling tip at the tip. The conical bit is rotatably mounted in the holder by inserting the mounting shaft portion through a spring pin (connector) through a through-hole mounting hole formed in the holder.

  Since this conical bit is rotatably attached to the holder, when the excavation tip is rotated by receiving excavation resistance when excavating the ground, the excavation tip wears evenly without being unevenly worn (decrease), It can withstand long-term use.

JP 2004-92200 A

  However, in the conventional conical bit, there is a possibility that the mounting shaft portion may be fixed to the holder due to the intrusion of earth and sand into the mounting hole (between the holder and the mounting shaft portion) during excavation.

  In particular, in the ground improvement work in which the solidified material is mixed with the excavated soil and agitated, the solidified material as well as the soil penetrates into the mounting hole, and the intruded solidified material is solidified. This may cause the mounting shaft portion to be fixed to the holder. Also, in ground improvement construction, sand, gravel, and clay ground layers are excavated rather than hard rock layers and stirred with solidifying agents in the ground, so the ground is not self-supporting and tightening due to earth pressure occurs. As a result, the wear of the drilling tip may become severe.

  When the mounting shaft of the conical bit sticks to the holder, the conical bit becomes unrotatable with respect to the holder, and the excavation tip at the tip of the conical bit suddenly deviates and wears (decreases) frequently. Therefore, it is necessary to replace the conical bit, which may increase cost and work time.

  Also, if the conical bit mounting shaft is fixed to the holder, it will be difficult to remove the conical bit from the holder, and in some cases, it will be necessary to replace the entire holder, further increasing costs and work. There was a risk of inviting.

  Therefore, in the present invention according to claim 1, in the conical bit that is detachably and rotatably attached to the holder provided in the excavation head, the bit main body portion provided with the excavation tip at the tip is rotatably supported by the holder. And a fixing preventing means for preventing the mounting shaft portion from being fixed to the holder and becoming unrotatable.

  Further, in the present invention according to claim 2, in the present invention according to claim 1, the sticking prevention means is provided with a seal member on the distal end side with respect to a connector interposed between the holder and the mounting shaft portion. The earth and sand excavated by the bit main body portion is prevented from entering the coupler between the holder and the mounting shaft portion so that the mounting shaft portion is fixed to the holder and cannot be rotated.

  Further, in the present invention according to claim 3, in the present invention according to claim 2, a through hole-shaped mounting hole through which the mounting shaft portion is inserted is formed in the holder, and only the distal end side of the coupling tool is formed. Instead, the sealing member is provided on the base end side.

  Further, in the present invention according to claim 4, in the present invention according to claim 1, the sticking prevention means is configured such that the outer peripheral surface of the bit main body portion has a polygonal pyramid shape and the mounting shaft portion is subjected to earth pressure received by the bit main body portion It was decided to prevent the mounting shaft portion from being fixed to the holder and becoming impossible to rotate by generating a rotational force.

  Further, in the present invention according to claim 5, in the present invention according to claim 4, in the corner portion or the surface portion of the bit body portion having the polygonal pyramid shape, a carbide chip harder than other portions is provided. did.

  And in this invention, there exists an effect described below.

  That is, in the present invention, in a conical bit that is detachably and rotatably attached to a holder provided on the excavation head, a bit body portion provided with an excavation tip at the tip and an attachment shaft portion that is rotatably supported by the holder. The drilling tip at the tip of the conical bit is abruptly biased and worn (reduced) because the mounting shaft portion has a sticking prevention means for preventing the mounting shaft portion from sticking to the holder and becoming unrotatable. ), And it is no longer necessary to replace the conical bit and the holder, and the frequency of replacing the conical bit and the holder can be suppressed, so that the cost required to replace the conical bit and the holder can be reduced. And work time can be reduced.

  In particular, when the sealing member is provided on the tip side of the connecting member interposed between the holder and the mounting shaft portion as the sticking prevention means, the earth and sand excavated by the bit body portion is formed between the holder and the mounting shaft portion. Since it is possible to prevent intrusion into the intermediate connector, it is possible to prevent the attachment shaft portion from being fixed to the holder and being unable to rotate.

  Further, a through-hole-shaped mounting hole through which the mounting shaft portion is inserted into the holder is formed, and when the seal member is provided not only at the distal end side but also at the proximal end side of the coupling tool, the mounting hole Intrusion of earth and sand from the rear side of the can also be prevented.

  Furthermore, when the outer peripheral surface of the bit main body portion is formed in a polygonal pyramid shape as the sticking prevention means, a rotational force can be generated in the mounting shaft portion by earth pressure received by the bit main body portion. It is possible to prevent the rotation from being fixed by being fixed to the holder.

  Moreover, when the carbide | carbonized_material chip | tip harder than another part is provided in the corner | angular part or surface part of the bit main-body part made into the said polygonal pyramid shape, abrasion of a bit main-body part can be prevented.

The side view which shows a ground improvement apparatus. The side view which shows a digging head. The bottom view. The partial enlarged bottom view. Explanatory drawing which shows a conical bit (a front view (a), a side fragmentary sectional view (b)). Explanatory drawing which shows a conical bit (a front view (a), a side fragmentary sectional view (b)). Explanatory drawing which shows a conical bit (a front view (a), a side fragmentary sectional view (b)). Explanatory drawing which shows a conical bit (a front view (a), a side fragmentary sectional view (b)). Explanatory drawing which shows a conical bit (a front view (a), a side fragmentary sectional view (b)). Explanatory drawing which shows a conical bit (a front view (a), a side fragmentary sectional view (b)). Explanatory drawing which shows a conical bit (a front view (a), a side fragmentary sectional view (b)). Explanatory drawing which shows a conical bit (a front view (a), a side fragmentary sectional view (b)). Explanatory drawing which shows a conical bit (a front view (a), a side fragmentary sectional view (b)).

  The specific configuration of the present invention will be described below with reference to the drawings. In the following description, the case where the present invention is applied to a ground improvement device that improves the ground excavated together with excavation of the ground will be described, but the present invention is not limited thereto, and the present invention is applied to various devices that excavate the ground. Can be applied.

  As shown in FIGS. 1 to 3, the ground improvement device 1 excavates the ground 2 and stirs and mixes the excavated soil and the ground improvement material (solidification material), thereby improving the strength and properties of the ground 2. It is a device that can do. In this ground improvement device 1, a support column 4 is erected at the front end of a heavy machine 3, and an excavation device 5 is attached to the support column 4 so as to be movable up and down. A ground improvement material supply mechanism 6 is connected to the excavator 5 via a swivel joint 7. The ground improvement material supply mechanism 6 connects the ground improvement material storage tank 8 and the water tank 9 to the ground improvement material mixing plant 10 and connects the ground improvement material discharge pump 11 to the ground improvement material mixing plant 10 to improve the ground. The material is configured to be supplied to the excavator 5.

  The excavator 5 has a lifting support 12 attached to the front side of the support column 4 so as to be movable up and down, a driving body 13 is attached to the lifting support 12, and a base end portion of the excavation shaft 14 is vertically extended on the driving body 13. (Upper end part) is attached, and the rotary excavation part 15 is attached to the tip part (lower end part) of the excavation shaft 14. The rotary excavation unit 15 is connected to a ground improvement material supply mechanism 6 so that the supplied ground improvement material can be discharged. Here, the rotary excavation unit 15 excavates by rotation, and the ground improvement device 1 has a function of stirring and mixing the ground and the ground improvement material in addition to excavation of the ground 2. ing.

  The driving body 13 has a driving motor 18 connected to an inner shaft 16 and an outer shaft 17 constituting the excavating shaft 14 via a reverse transmission 19.

  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 protrudes the tip portion of the inner shaft 16 downward from the tip portion of the outer shaft 17. The inner shaft 16 or the outer shaft 17 rotates in a relatively opposite direction by the action of the reverse transmission 19 by driving the drive motor 18.

  The rotary excavation unit 15 has an excavation head 20 and an agitating blade 21 attached to the distal end portion (lower end portion) of the excavation shaft 14 in order from the distal end side.

  In the excavation head 20, the excavation blade 22 is attached to the outer peripheral surface of the distal end portion of the inner shaft 16, and a plurality of excavation bits 23 are attached to the excavation blade 22. In the excavation head 20, the excavation blade 22 rotates with the rotation of the inner shaft 16, and excavates the ground 2 with the excavation bit 23. The detailed configuration of the excavation head 20 will be described later.

  The stirring blade 21 includes an innermost stirring blade 24, an inner stirring blade 25 disposed on the outer peripheral side thereof, and an outer stirring blade 26 disposed on the outer peripheral side thereof.

  The innermost agitating blade 24 is radially attached to the outer peripheral surface of the outer shaft 17 with two flat innermost agitating blade bodies 27 facing the circumferential direction and spaced outward by 180 degrees. ing.

  The inner stirring blade 25 has two inner stirring blade bodies 28 radially attached to the tip of the inner shaft 16 at an interval of 180 degrees in the circumferential direction. Each inner stirring blade body 28 has an inner stirring blade upper piece 29 extending in an inclined manner toward the outer lower part, an inner stirring blade intermediate piece 30 extending vertically downward, and an outer upper part. The inner stirring blade lower piece 31 extending in an inclined shape is formed in a substantially U shape in a side view in which a midway portion is bulged outward. Each inner stirring blade body 28 has the inner stirring blade lower piece 31 attached to the tip end side of the inner shaft 16, the inner stirring blade upper piece 29 attached to the annular body 32, and the annular body 32 on the outer peripheral surface of the outer shaft 17. It is loosely fitted freely. Further, each inner stirring blade body 28 has a stirring piece 33 attached to the outer side of the inner stirring blade halfway piece 30, and a connecting piece 34 is attached between the inner stirring blade halfway piece 30 and the inner shaft 16. .

  The outer agitating blade 26 has three outer agitating blade bodies 35 radially attached to the front end portion of the outer shaft 17 at an interval of 120 degrees in the circumferential direction. Each outer stirring blade body 35 includes an outer stirring blade upper piece 36 that extends in an inclined manner toward the outer lower portion, an outer stirring blade middle piece 37 that extends vertically downward, and an outer upper portion. The outer stirring blade lower piece 38 extending in an inclined shape is formed in a substantially U shape in a side view in which a midway portion is bulged outward. Each outer stirring blade body 35 has an outer stirring blade upper piece 36 attached to the tip end side of the outer shaft 17, an outer stirring blade lower piece 38 attached to the annular body 39, and the annular body 39 on the outer peripheral surface of the inner shaft 16. It is loosely fitted freely. Each outer stirring blade body 35 has a stirring piece 40 attached to the inner side of the outer stirring blade middle part 37.

  The ground improvement device 1 is configured as described above. And the detail of the excavation head 20 of the excavation apparatus 5 used as the principal part of this invention is comprised so that it may demonstrate below.

  In the excavation head 20, an excavation blade 22 composed of two spiral blades 41 having a substantially spiral plate shape and two horizontal blades 42 having a substantially horizontal plate shape is attached to the tip (lower end) of the inner shaft 16.

  The spiral blade 41 has a spiral portion 43 that continuously increases in diameter upward from the tip (lower end) of the inner shaft 16 and a diameter that gradually increases in the middle (from the center of the inner shaft 16 toward the radial direction). A plurality of step portions 44 (extending) are formed. A plurality of conical bits 45 are attached to each step 44 in the radial direction as excavation bits 23. The conical bit 45 is also attached to the tip (lower end) of the inner shaft 16, the lower surface of the spiral portion 43 of the spiral blade 41, and the outer peripheral portion of the horizontal blade 42.

  In the conventional excavation head, when a plurality of excavation bits are mounted side by side on a horizontal wing, there is a possibility that excavation resistance during excavation increases. In particular, in the ground improvement work that excavates the ground and mixes solidified material with the excavated soil and agitate, the drilling diameter is very large compared to the excavation work, so the excavation resistance during construction is very large. There is a risk of becoming. In the conventional excavation head, in the case of a configuration in which a plurality of excavation bits are arranged side by side along the outer periphery of the spiral blade expanded from the lower end upward, a conical portion excavated by the expanded spiral blade ( The conical column body) may become long. In particular, in the ground improvement work, the columnar column body formed above the conical column body is a product that exhibits effective strength, and the conical column body becomes invalid, so it is invalid. A long conical column body may become long.

  However, in the excavation head 20, a stepped portion 44 whose diameter is increased stepwise is formed in the middle of the excavating blade 22 (spiral blade 41), and a drilling bit (conical bit 45) is provided in the stepped portion 44. Therefore, the length of the conical column body can be shortened while reducing the excavation resistance during excavation.

  The conical bits 45 mounted side by side on the stepped portion 44 may be arranged side by side as shown in FIG. 4 (a), and as shown in FIGS. 4 (b) and (c), You may shift | deviate and arrange | position back and forth on the peripheral side and the outer peripheral side. When placed side by side (without shifting back and forth) as shown in Fig. 4 (a), the ground can be excavated evenly, and the standard ground such as sand or clay is targeted Suitable for 4B, when the conical bit 45 on the inner peripheral side of the excavating blade 22 is preceded by the conical bit 45 on the outer peripheral side, the inner peripheral portion (center portion) is excavated faster. It is suitable for hard ground such as hard ground and rock formation. Furthermore, as shown in FIG. 4 (c), when the conical bit 45 on the outer peripheral side of the excavating blade 22 is preceded by the conical bit 45 on the inner peripheral side, the conical bit 45 on the outer peripheral side bites into the ground first. This makes it possible to excavate while preventing misalignment, and is suitable when the ground such as an inclined support layer is targeted.

  As described above, in the excavation head 20, a plurality of excavation bits (conical bits 45) are shifted back and forth on the inner peripheral side and the outer peripheral side of the excavation blades 22 according to the condition of the ground to be excavated, so that the ground Can be excavated well. Further, a normal excavation bit may be partially interwoven and arranged.

  Further, behind the conical bit 45 mounted side by side on the stepped portion 44, the conical bit 45 is mounted on the lower surface of the spiral portion 43 of the spiral blade 41 so as to be positioned between the conical bits 45 arranged side by side.

  Thus, in the excavation head 20, the ground can be excavated satisfactorily by providing the excavation bit (conical bit 45) between the plural excavation bits (conical bit 45) and at the rear position. I can do it.

  In the excavation head 20, a plurality of excavation bits (conical bits 45) are mounted side by side on the step portion 44. However, the present invention is not limited to this, and a plurality of excavation bits (conical bits 45) are mounted side by side on the spiral portion 43 or the like. May be.

  The conical bit 45 is detachably and rotatably attached to a holder 46 attached to the excavation blade 22 of the excavation head 20.

  As shown in FIG. 5, the conical bit 45 has a bit body portion 47 formed on the distal end side and an attachment shaft portion 48 formed on the proximal end side, and is confined between the bit body portion 47 and the attachment shaft portion 48. A portion 49 and a flange portion 50 are formed.

  The bit body 47 has a conical (sharpened) carbide (harder than other parts) drilling tip 51 attached to the tip (front end), and linearly expands from the base end of the drilling tip 51 to the rear. By forming a conical surface with a diameter, a cylindrical surface with the same diameter, a circumferential surface expanded in a curved shape toward the rear, and a cylindrical surface with the same diameter, the outer peripheral surface becomes a discontinuous surface having corners. The base end (rear end) is connected to the constricted portion 49.

  The attachment shaft portion 48 forms a small-diameter cylindrical base end portion on the base end side (rear side) of the large-diameter cylindrical tip portion (front end portion). Correspondingly, the holder 46 has a large-diameter circular hole-shaped distal end into which the mounting shaft 48 is inserted, and a small-diameter circular hole-based proximal end into which the mounting shaft 48 is inserted. A through-hole-like mounting hole 52 having a portion is formed. Then, the conical bit 45 is attached to and detached from the holder 46 by inserting the attachment shaft portion 48 into the attachment hole 52 of the holder 46 via a connector 53 (a spring pin made of an elastic material having a C-shaped cross section). It can be mounted freely and freely. The connector 53 is accommodated in an accommodation recess 54 formed by reducing the diameter at the tip of the mounting shaft portion 48.

  The constricted portion 49 is smaller in diameter than the proximal end (rear end) of the bit body portion 47 and the distal end (front end) of the flange portion 50, and can be gripped with a tool when the conical bit 45 is attached or detached. .

  The flange portion 50 has a diameter larger than the opening diameter of the tip of the mounting hole 52 of the holder 46, and comes into contact with the tip of the holder 46 with the conical bit 45 attached to the holder 46. The conical bit 45 has a smaller diameter than the holder 46 as a whole, and prevents the excavation head 20 from coming out of the holder 46 when the excavation head 20 rotates in the reverse direction of excavation.

  In the conventional conical bit, there is a possibility that the mounting shaft portion may be fixed to the holder due to the intrusion of earth and sand into the mounting hole (between the holder and the mounting shaft portion) during excavation. In particular, in the ground improvement work in which the solidified material is mixed with the excavated soil and agitated, the solidified material as well as the soil penetrates into the mounting hole, and the intruded solidified material is solidified. This may cause the mounting shaft portion to be fixed to the holder. Also, in ground improvement construction, sand, gravel, and clay ground layers are excavated rather than hard rock layers and stirred with solidifying agents in the ground, so the ground is not self-supporting and tightening due to earth pressure occurs. As a result, the wear of the drilling tip may become severe. When the mounting shaft of the conical bit sticks to the holder, the conical bit becomes unrotatable with respect to the holder, and the excavation tip at the tip of the conical bit suddenly deviates and wears (decreases) frequently. Therefore, it is necessary to replace the conical bit, which may increase cost and work time. Also, if the conical bit mounting shaft is fixed to the holder, it will be difficult to remove the conical bit from the holder, and in some cases, it will be necessary to replace the entire holder, further increasing costs and work. There was a risk of inviting.

  Therefore, the conical bit 45 is provided with an anti-adhesion means for preventing the attachment shaft portion 48 from adhering to the holder 46 and being unable to rotate. Thereby, in the said conical bit 45, it can prevent that the excavation tip 51 at the front-end | tip of the conical bit 45 is abruptly biased and worn out (decrease part) by a sticking prevention means, and also the conical bit 45 and the holder Since it is not necessary to replace the conical bit 45 and the replacement frequency of the conical bit 45 and the holder 46 can be suppressed, the cost and work time required for replacing the conical bit 45 and the holder 46 can be reduced.

  In the conical bit 45 shown in FIG. 5, a sealing member 55 made of an O-ring or the like is provided as a sticking prevention means on the tip side of the connector 53 interposed between the holder 46 and the mounting shaft portion 48. The seal member 55 is accommodated in a recess 56 formed by reducing the diameter at the distal end of the mounting shaft portion 48 from the distal end side of the accommodation recess 54. Thereby, the conical bit 45 can prevent the earth and sand excavated by the bit main body portion 47 from entering the coupling member 53 between the holder 46 and the mounting shaft portion 48. It is possible to prevent the rotation from being fixed due to sticking to.

  Further, in the conical bit 45 shown in FIG. 5, a seal member 57 made of an O-ring or the like is provided not only on the distal end side but also on the proximal end side of the connector 53 as a sticking prevention means. The seal member 57 is accommodated in a recess 58 formed by reducing the diameter at the base end portion on the base end side with respect to the housing recess 54 of the mounting shaft portion 48. Thereby, intrusion of earth and sand from the rear side of the mounting hole 52 can be prevented. In the conical bit 45, the seal member 55, 57 is provided at the large-diameter tip portion and the small-diameter base end portion to prevent the conical bit 45 from wobbling with respect to the holder 46.

  The sticking prevention means is not limited to the structure provided with the seal members 55 and 57 as long as it can prevent the mounting shaft portion 48 from sticking to the holder 46 and becoming unrotatable. Alternatively, other configurations can be used.

  For example, in the conical bit 59 shown in FIG. 6, as a sticking prevention means, the base end side (rear side) of the excavation tip 51 of the bit body 60 is formed in a polygonal frustum shape (here, a hexagonal frustum shape), and the bit The outer peripheral surface of the main body 60 has a polygonal pyramid shape (here, a hexagonal pyramid shape), and the cross section perpendicular to the rotation center axis (center line) of the bit main body 60 has a polygonal shape (here, a hexagon). Then, a plurality of (here, six) bit surface portions of the bit body portion 60 are provided with plate-like carbide tips 61 that are harder than the other portions (having the same hardness as the excavation tip 51) from the distal end portion to the proximal end portion. It is extended in a straight line toward the side.

  Further, in the conical bit 62 shown in FIG. 7, as a means for preventing sticking, the base end side (rear side) of the excavation tip 51 of the bit body 63 is formed in a polygonal frustum shape (here, a pentagonal frustum shape), The outer peripheral surface of the main body 63 is a polygonal pyramid shape (here, a hexagonal pyramid shape), and the cross section orthogonal to the rotation center axis (center line) of the bit main body 63 is a polygon (here, a pentagon). Then, a plurality of (here, 5) corner portions of the bit main body 63 have plate-shaped carbide tips 64 that are harder than the other portions (having the same hardness as the drilling tips 51) from the distal end portion to the proximal end portion. It is extended in a straight line toward the side.

  As described above, in the conical bits 59 and 62 shown in FIGS. 6 and 7, the outer peripheral surface of the bit main body portions 60 and 63 has a polygonal pyramid shape as an anti-sticking means, and therefore the earth pressure received by the bit main body portions 60 and 63 is reduced. Since the rotational force can be generated in the mounting shaft portion 48, the conical bits 59 and 62 are forcibly rotated with respect to the holder 46, and the mounting shaft portion 48 is fixed to the holder 46 and cannot be rotated. Can be prevented. In particular, when carbide tips 61 and 64 that are harder than other portions are provided at the corners or surface portions of the bit body portions 60 and 63 having a polygonal pyramid shape, the outer peripheral surface of the bit body portions 60 and 63 is worn. Can be prevented.

  Furthermore, in the conventional conical bit, there is a possibility that the holder will be worn and damaged due to the earth and sand coming into contact with the holder during excavation. In particular, in the ground improvement work that excavates the ground and mixes the solidified material into the excavated soil and agitate, the sand, gravel, and clay ground layers are excavated from the hard rock layer and stirred with the solidifying agent in the ground. Therefore, the ground is not self-supporting and tightening due to earth pressure occurs, and there is a possibility that the wear of the holder becomes severe. If the holder for detachably attaching the conical bit is worn out and damaged, it becomes necessary to remove the damaged holder from the drilling blade and attach a new holder to the drilling blade. There was a risk of increasing time. In addition, if the holder is worn and damaged, it becomes difficult to remove the conical bit from the holder. In some cases, it becomes necessary to replace the conical bit together with the holder, which further increases costs and increases work. There was a risk of inviting.

  Therefore, the conical bit 45 shown in FIG. 5 can be provided with wear suppression means for suppressing the wear of the holder 46 during excavation. As a result, damage due to wear of the holder 46 can be prevented, and the replacement frequency of the holder 46, the holder 46, and the conical bit 45 can be suppressed. Therefore, the cost and work time required to replace the conical bit 45 and the holder 46 are reduced. Can be reduced.

  In the conical bit 65 shown in FIG. 8, the flange portion 66 has a diameter larger than the proximal end of the bit body portion 47 (the distal end or the proximal end of the constricted portion 48) as a wear suppressing means so as to cover the front surface of the holder 46. I have to. Thereby, in the conical bit 65, since the impact of the earth and sand on the holder 46 can be suppressed by the flange portion 66 having an enlarged diameter, the wear of the holder 46 during excavation can be suppressed. Further, in the conical bit 65 shown in FIG. 8, cylindrical carbide tips 67 that are harder than the other portions of the flange portion 66 (having the same hardness as the excavation tip 51) are equally spaced in the circumferential direction on the same circle. The gap is embedded in an inclined manner from the outer peripheral side of the tip toward the inner peripheral side of the base end, thereby preventing wear of the flange portion 66.

  The wear suppression means may be any configuration that can suppress the wear of the holder 46 during excavation, and is not limited to the configuration in which the diameter of the flange portion 66 is increased. The thing of the structure of can also be used.

  For example, in the conical bit 68 shown in FIG. 9, as wear suppression means, the base end side (rear side) of the excavation tip 51 of the bit main body portion 69 is formed into a truncated cone shape, and the outer peripheral surface of the bit main body portion 69 is formed into a conical shape. By making the cross section orthogonal to the rotation center axis (center line) of the bit body portion 69 into a circular shape whose diameter is gradually increased along the rotation center axis, the outer peripheral surface of the bit body portion 69 is made a continuous surface without corner portions. Yes.

  Further, in the conical bit 70 shown in FIG. 10, the outer peripheral surface of the bit main body 71 has a conical shape, and a part of the outer peripheral surface is harder than the other parts (having the same hardness as the drilling tip 52). A plurality of cemented carbide tips 72 are linearly extended from the distal end portion toward the proximal end portion, and a plurality of carbide tips 72 are attached at equal intervals in the circumferential direction.

  Further, in the conical bit 73 shown in FIG. 11, the outer peripheral surface of the bit main body 74 has a conical shape, and a part of the outer peripheral surface is harder than other portions (having the same hardness as the drilling tip 52). A plurality of cemented carbide tips 75 are mounted on the same straight line at equal intervals in the circumferential direction from the distal end to the proximal end.

  Further, in the conical bit 76 shown in FIG. 12, the outer peripheral surface of the bit main body 77 has a conical shape with a plurality of stages (here, three stages) and is harder than the other parts at the intermediate part (the same as the excavation tip 51) An annular cemented carbide tip 78 (hardness) is attached at an interval in the front-rear direction.

  Further, in the conical bit 79 shown in FIG. 13, the entire outer peripheral surface of the bit main body 80 is formed of a cemented carbide tip that is harder than other portions (having the same hardness as the drilling tip 51). The whole is a drilling tip 81. The excavation tip 51 may be provided on the tip side, and the entire conical outer peripheral surface of the bit body 80 may be covered with a carbide tip different from the excavation tip 51.

  As described above, in the conical bits 68, 70, 73, 76, 79 shown in FIGS. 9 to 13, the outer peripheral surface of the bit main body 69, 71, 74, 77, 80 has a conical shape as a wear suppressing means. Since the collision of the earth and sand with the holder 46 can be suppressed by the conical bit body portions 69, 71, 74, 77, 80, the wear of the holder 46 during excavation can be suppressed.

  In particular, in the conical bits 70, 73, 76, 79 shown in FIG. 10 to FIG. 13, carbide tips 72, 75, which are harder than the other parts on the outer peripheral surface of the conical shape of the bit main body portions 71, 74, 77, 80. Since 78 and 81 are provided entirely or partially, it is possible to prevent the outer peripheral surfaces of the bit body portions 71, 74, 77, and 80 from being worn.

DESCRIPTION OF SYMBOLS 1 Ground improvement device 2 Ground 3 Heavy machine 4 Prop 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 Lifting support
13 Drive 14 Drilling shaft
15 Rotary excavation 16 Inner shaft
17 Outer shaft 18 Drive motor
19 Reverse transmission 20 Drilling head
21 Stirring blade 22 Drilling blade
23 Drilling bit 24 Innermost stirring blade
25 Inner stirring blade 26 Outer stirring blade
27 Inner stirring blade 28 Inner stirring blade
29 Inner stirring blade upper piece 30 Inner stirring blade middle piece
31 Inner stirring blade lower piece 32 Annulus
33 Stirring piece 34 Connecting piece
35 Outer stirring blade body 36 Outer stirring blade upper piece
37 Middle part of outer stirring blade 38 Lower part of outer stirring blade
39 Ring 40 Stirring piece
41 Spiral wing 42 Horizontal wing
43 Spiral part 44 Step part
45 Conical Bit 46 Holder
47 Bit body 48 Mounting shaft
49 Narrow part 50 Flange part
51 Drilling tip 52 Mounting hole
53 Connector 54 Recess
55,57 Seal member 56,58 Recess
59,62 Conical bit 60,63 bit body
61,64 Carbide tip 65,68,70,73,76,79 Conical bit
66 Flange 67,72,75,78 Carbide tip
69,71,74,77,80 Bit body 81 Drilling tip

Therefore, in the present invention according to claim 1, in the conical bit that is detachably and rotatably attached to the holder provided in the excavation head, the bit main body portion provided with the excavation tip at the tip is rotatably supported by the holder. and a mounting shaft portion, houses the coupling between the holder and the mounting shaft portion, the mounting shaft portion have a sticking prevention means for preventing from becoming unrotatable by fixing the holder, fixed The prevention means is that the seal member is housed between the holder and the mounting shaft portion on the tip side of the coupling member housed between the holder and the mounting shaft portion, and the earth and sand excavated by the bit main body portion is held between the holder and the mounting shaft. It was decided to prevent the attachment shaft portion from being fixed to the holder and becoming unrotatable by intruding into the connector accommodated between the two portions .

Further, in the present invention according to claim 2 , in the present invention according to claim 1 , a through-hole-shaped mounting hole for inserting the mounting shaft portion through the holder is formed, and only the distal end side of the coupling tool is formed. not even the base end side was Rukoto to accommodate the sealing member between the holder and the mounting shaft portion.

Further, in the present invention according to claim 3, occurs in the present invention according to claim 1, the outer peripheral surface of the bit body portion as a pyramid shape, a rotational force to the mounting shaft portion by soil pressure bit body portion receives By doing so, it was decided to prevent the mounting shaft portion from being fixed to the holder and becoming unrotatable.

Further, in the present invention according to claim 4 , in the present invention according to claim 3 , in the corner portion or the surface portion of the bit body portion having the polygonal pyramid shape, a carbide chip harder than other portions is provided. did.

Claims (5)

In a conical bit that is detachably and rotatably attached to a holder provided on a drilling head,
It has a bit body portion provided with a drilling tip at the tip, and an attachment shaft portion that is rotatably supported by the holder,
A conical bit, characterized by having a sticking prevention means for preventing the mounting shaft portion from sticking to the holder and becoming unrotatable.   The sticking prevention means is provided with a seal member on the tip side of a connecting tool interposed between the holder and the mounting shaft portion, and the earth and sand excavated by the bit main body portion becomes a connecting tool between the holder and the mounting shaft portion. 2. The conical bit according to claim 1, wherein the conical bit prevents the attachment shaft portion from adhering to the holder and becoming unrotatable by intrusion.   3. A through-hole-shaped mounting hole through which the mounting shaft portion is inserted is formed in the holder, and the seal member is provided not only on the distal end side but also on the proximal end side of the coupling tool. Conical bit as described in.   The sticking prevention means has an outer peripheral surface of the bit body portion formed in a polygonal pyramid shape, and causes the mounting shaft portion to be fixed to the holder and cannot be rotated by generating a rotational force on the mounting shaft portion by earth pressure received by the bit body portion. 2. The conical bit according to claim 1, wherein the conical bit is prevented.   5. The conical bit according to claim 4, wherein a carbide tip harder than other portions is provided at a corner portion or a surface portion of the bit body portion having the polygonal pyramid shape.

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