JP7793582B2 - Expanding Drilling Rig - Google Patents

Description

The present invention relates to an excavation enlargement device for excavating the tip of a pile hole formed in the ground to construct a root protection bulb.

One example of an enlargement drilling device used to enlarge the tip of a pile hole formed underground and form a root-hardening bulb is the enlargement drilling device described in Patent Document 1. This enlargement drilling device comprises a drilling shaft that can be connected integrally to the tip of the drilling rod, multiple support shafts that are parallel to the axis of the drilling shaft on the outer periphery of the drilling shaft and are equally spaced circumferentially around the drilling shaft, and enlargement blades rotatably attached to each support shaft. During pile hole excavation work in which the drilling rod rotates forward, the enlargement blades remain in a contracted state due to the application of earth pressure. During enlargement drilling work in which the drilling rod rotates backward, the enlargement blades rotate around the support shaft and become expanded due to the application of earth pressure. In this state, the multiple enlargement blades rotate together with the drilling shaft, enlarging and drilling the surrounding ground.

Japanese Patent Application Laid-Open No. 2023-116136

In the above-mentioned conventional expansion drilling device, when performing expansion drilling work, the drilling rod, which is rotating forward, is rotated in the reverse direction so that the expansion blades open under soil pressure. However, because the expansion blades are closed when the drilling rod begins to rotate in the reverse direction, even when they come into contact with the hole wall, friction is small and they tend to slide along the hole wall. As a result, there is a time loss between the start of reverse rotation and the expansion blades beginning to open.

The present invention therefore aims to provide an expansion drilling device that can quickly open the expansion wings to perform expansion drilling when the drilling rod begins to rotate in reverse.

The expansion drilling device of the present invention comprises a drilling shaft that can be connected to the drilling rod so as to rotate integrally with it; multiple support shafts that are parallel to the axis of the drilling shaft on the outer periphery of the drilling shaft and are equally spaced circumferentially of the drilling shaft; and expansion blades that are rotatably attached to each of the multiple support shafts. During pile hole drilling operations in which the drilling rod rotates forward, the expansion blades receive earth pressure and maintain a reduced diameter state. During expansion drilling operations in which the drilling rod rotates reversely, the expansion blades receive earth pressure and rotate around the support shafts, expanding until a portion of the expansion blade abuts the outer periphery of the drilling shaft and maintaining an expanded diameter state. A first drill bit is provided on the outer surface of the tip of the expansion blade in a position that first contacts the hole wall when the drilling rod begins reverse rotation.

With the expansion drilling device of the present invention, when the drilling rod rotates forward to perform pile hole drilling operations and then rotates backward to perform expansion drilling operations, the first drilling bit attached to the outer surface of the tip of the expansion wing comes into contact with the hole wall first, generating friction early on and allowing the expansion wing to open quickly.

The expansion drilling device of the present invention desirably has a second drilling bit at the tip of the expansion wing that contacts the hole wall when in the expanded diameter state. This allows the second drilling bit to contact the hole wall when the expansion wing is in the expanded diameter state, making it possible to accurately cut the hole wall.

Here, it is desirable that the orientation of the second drilling bit be such that its angle with respect to the reverse rotation direction of the drilling rod is between 0° and 25°, more preferably between 0.2° and 12°. This allows the second drilling bit to efficiently receive the mechanical stress applied by the hole wall and cut the hole wall when the drilling rod is pulled up or down while rotating in the reverse direction to enlarge and drill the hole wall.

It is also desirable that the expansion blades rotate at an angle of 0° to 25°, more preferably 0.2° to 12°, relative to the direction of reverse rotation of the drilling rod. This allows the expansion blades to efficiently absorb the mechanical stress applied by the hole wall and open quickly when the drilling rod is pulled up or down while rotating in the reverse direction to enlarge and drill the hole wall. In particular, when the drilling rod is pulled up while rotating in the reverse direction to enlarge and drill the hole wall, the inclined expansion blades also act as gravity, making them easier to open, and also dispersing the downward stress applied when cutting the hole wall.

(1) By providing a first drilling bit on the outer surface of the tip of the expansion wing at a position that first contacts the hole wall when the drilling rod begins to reverse rotate, it is possible to quickly open the expansion wing and perform enlarged hole drilling.

(2) By providing a second drilling bit at the tip of the expansion wing that contacts the hole wall when in the expanded diameter state, it is possible to accurately cut the hole wall with the second drilling bit when the expansion wing is in the expanded diameter state, thereby performing enlarged hole drilling.

(3) By orienting the second drilling bit at an angle of 0° to 25°, more preferably 0.2° to 12°, relative to the reverse rotation direction of the drilling rod, when the drilling rod is pulled up or down while rotating in the reverse direction to drill the hole wall, the mechanical stress applied from the hole wall is efficiently received by the second drilling bit, cutting the hole wall and improving hole wall drilling efficiency. This also improves the mechanical strength of the second drilling bit.

(4) Because the expansion wing rotates at an angle between 0° and 25° relative to the direction of reverse rotation of the drilling rod, when the drilling rod is pulled up or down while rotating in the reverse direction to enlarge the hole wall, the expansion wing efficiently absorbs the mechanical stress applied from the hole wall, allowing the expansion wing to quickly open and perform enlargement drilling. In particular, when the drilling rod is pulled up while rotating in the reverse direction to enlarge the hole wall, the inclined expansion wing also acts as a force of gravity, making it easier for the expansion wing to open. In addition, the downward stress applied when cutting the hole wall is dispersed, improving the load-bearing capacity of the expansion wing.

FIG. 2 is a front view showing a state in which the expansion wing of the expansion drilling device according to the embodiment of the present invention is in a contracted diameter state. FIG. 2 is a plan view of the expansion drilling device of FIG. 1; FIG. 2 is a front view showing the expansion wing of the expansion drilling device of FIG. 1 in an expanded state. FIG. 4 is a plan view of the expansion drilling device of FIG. 3. FIG. 2 is a view taken along the arrow X in FIG. 1 , with the expansion wing omitted. FIG. 2 is a front view showing a state in which a drilling head is connected to the expansion drilling device of FIG. 1 . FIG. 2 is a perspective view showing a state in which a drilling head is connected to the expansion drilling device of FIG. 1 . FIG. 2 is a vertical cross-sectional view showing the expansion drilling device of FIG. 1 in use (with the expansion wings contracted). FIG. 10 is an explanatory diagram showing the orientation of the drilling bit at the tip of the expansion wing cutting the hole wall when the angle of the expansion wing support shaft is 0°. FIG. 10 is an explanatory diagram showing the direction of the drilling bit at the tip of the expansion wing cutting the hole wall when the angle of the expansion wing support shaft is θ.

As shown in Figure 8, the enlarged drilling device 100 in this embodiment of the present invention is used to enlarge and excavate the tip of a pile hole H formed in the ground to create a root protection bulb (not shown). The enlarged drilling device 100 is attached to the tip of a drilling rod 1. The drilling rod 1 includes a drive shaft 2 that is driven to rotate in forward and reverse directions by a drive means (not shown) such as an auger machine, and a spiral drilling blade 3 attached to the outer periphery of the drive shaft 2.

As shown in Figures 1 to 4, the expansion drilling device 100 comprises a drilling shaft 10 that can be connected to the drilling rod 1 (see Figure 8) so as to rotate integrally therewith, two support shafts 13 provided on the outer periphery of the drilling shaft 10, and two expansion wings 11 rotatably attached to each support shaft 13. A drilling head 20 is connected to the lower end of the drilling shaft 10, as shown in Figures 5 and 6.

The drilling shaft 10 has a shaft portion 12 shaped like a cylinder with its side surface centered on the axis 10c cut off by two flat surfaces 12a, 12a. The two flat surfaces 12a, 12a are formed parallel to the axis 10c, facing each of the two expansion wings 11, and are positioned to avoid the areas where the support shafts 13 are located. The drilling shaft 10 is connected to the tip of the drive shaft 2 of the drilling rod 1 so as to rotate integrally with the drilling rod 1. A hexagonal prism-shaped connector 14a protrudes from the upper end of the shaft portion 12 of the drilling shaft 10 for connecting to the lower end of the drive shaft 2 of the drilling rod 1. A connector hole 14b is drilled in the direction of the axis 10c from the lower end of the shaft portion 12 of the drilling shaft 10, into which a connector 22 (see Figure 6) protruding from the upper end of the drive shaft 21 of the drilling head 20 can be fitted.

The two support shafts 13 are arranged on the arcuate surfaces 12b, 12b on the outer periphery of the shaft portion 12 of the drilling shaft 10, forming an angle θ (see Figure 5) with the axis 10c of the drilling shaft 10, and are equally spaced (180° apart) around the circumference of the drilling shaft 10. Each support shaft 13 is fixed at a position away from the arcuate surfaces 12b, 12b on the outer periphery of the shaft portion 12 of the drilling shaft 10 via a pair of brackets 16, 16 that are spaced apart in a direction parallel to the axis 10c as shown in Figures 1 and 2, and inclined at an angle θ with respect to the horizontal as shown in Figure 5.

During pile hole excavation work in which the drilling rod 1 rotates forward in the direction of arrow R, the expansion blade 11 is subjected to earth pressure and rotates around the support shaft 13 as shown in Figures 1 and 2, becoming housed within the rotational trajectory of the drilling blade 3. On the other hand, during enlarged excavation work in which the drilling rod 1 rotates backward in the direction of arrow L, the expansion blade 11 is subjected to earth pressure and rotates around the support shaft 13, becoming enlarged and protruding radially outward from the rotational trajectory of the drilling blade 3 as shown in Figures 3 and 4.

In the contracted state shown in Figures 1 and 2, the outer surface 11b of the tip 11a of the expansion wing 11 is provided with a first drilling bit 15a at a position that first contacts the hole wall when the drilling rod 1 begins reverse rotation. The tip 11a of the expansion wing 11 is also provided with a second drilling bit 15b that contacts the hole wall in the expanded state shown in Figures 3 and 4. The upper and lower surfaces of the tip of the expansion wing 11 are provided with third drilling bits 15c that cut the upper and lower surfaces of the hole wall into which the expansion wing 11 has entered when the expansion wing 11 is in the expanded state.

The expansion wing 11 has a front surface in the direction of arrow L, i.e., the surface that receives earth pressure during expansion excavation work, which has a convex surface 11c that curves rearward in the direction of arrow L as it moves away from the support shaft 13, and a concave surface 11d that is continuous with this convex surface 11c and curves forward on the opposite side, i.e., in the direction of arrow L. Furthermore, a protrusion 11e that protrudes away from the tip end is provided on the base end of the expansion wing 11. In this embodiment, the expansion wings 11 are arranged at two locations 180° apart around the outer periphery of the drilling shaft 10, but the shape, number, and spacing of the expansion wings 11 are not limited to this embodiment.

As shown in Figures 6 and 7, the drilling head 20 comprises a cylindrical drive shaft 21, a hexagonal connector 22 protruding from the upper end of the drive shaft 21, and spiral drilling blades 23 attached to the outer periphery of the drive shaft 21. A drilling bit 24 is attached to the tip of each drilling blade 23. The connector 22 on the upper end of the drilling head 20 is inserted into the connector hole 14b on the lower end of the drilling shaft 10 of the enlarged drilling device 100 and fixed using a predetermined fixing means, thereby integrally connecting the enlarged drilling device 100 and the drilling head 20.

Next, the enlarged drilling device 100 integrated with the drilling head 20 is connected to the tip of the drive shaft 2 of the drilling rod 1 so that it rotates integrally with the drilling rod 1. Specifically, the connector 14a on the upper end of the drilling shaft 10 of the enlarged drilling device 100 is inserted into the connector hole 4 (see Figure 8) drilled at the tip of the drive shaft 2 and fixed with a predetermined fixing means, thereby integrally connecting the drilling rod 1 to the enlarged drilling device 100 and drilling head 20. As a result, the enlarged drilling device 100 and drilling head 20 are connected to rotate integrally with the drilling rod 1.

Next, the operation of the expansion drilling device 100 having the above-described configuration will be described.
As shown in Figure 8, during pile hole excavation work, the drilling rod 1 is rotated forward in the direction of the arrow R. At this time, as shown in Figures 1 and 2, the tip end 11a of the expansion blade 11, which is subjected to earth pressure, is kept close to the drilling shaft 10, so the expansion blade 11 is kept in a reduced diameter state. Therefore, by rotating the drilling rod 1 forward in the direction of the arrow R, pile hole excavation work can be carried out smoothly.

On the other hand, during expansion drilling, the drill rod 1 is pulled up while rotating in the reverse direction of arrow L. At this time, as shown in Figures 3 and 4, the multiple expansion wings 11, subjected to earth pressure, rotate around the support shafts 13, causing the expansion wings 11 to expand. At this time, the first drilling bit 15a attached to the outer surface 11b of the tip 11a of the expansion wings 11 comes into contact with the hole wall first, generating friction early on and allowing the expansion wings 11 to open quickly.

The shaft portion 12 of the drilling shaft 10 has a cylindrical shape with a portion of its side surface centered on the axis 10c cut away by two flat surfaces 12a, 12a parallel to the axis 10c, sandwiching the axis 10c, toward the two expansion wings 11. This allows excavated soil to be present in the cut-off space, and when the drilling rod 1 rotates in the reverse direction, the excavated soil in this space flows toward the expansion wings 11, increasing the earth pressure that the expansion wings 11 receive. The shaft portion 12 can also be cut away diagonally toward the expansion wings 11 and parallel to the axis, as shown by the dashed line 17 in Figure 2. In this case, too, when the drilling rod 1 rotates in the reverse direction, the excavated soil in this space flows toward the expansion wings 11, increasing the earth pressure that the expansion wings 11 receive.

In addition, the expansion wing 11 has a space formed by its convex surface 11c and concave surface 11d that is easily able to receive excavated soil, allowing the excavated soil to flow smoothly along the convex surface 11c and concave surface 11d to the rear of the outer periphery, allowing the expansion wing to open quickly.

In this way, the expansion wings 11 expand until the protrusions 11e abut the outer periphery of the drilling shaft 10, and are maintained in the expanded diameter state shown in Figures 3 and 4. The second drilling bit 15b and the third drilling bit 15c of the multiple expansion wings 11 are then pulled up while rotating in the reverse direction of arrow L with a larger rotation radius than the drilling blade 23 (see Figure 8), thereby excavating and expanding the ground around the expansion wings 11 in the pile hole H formed in the ground as shown in Figure 8, and forming a root compaction bulb (not shown) with an inner diameter larger than that of the pile hole H.

The expansion wing 11 of the expansion drilling device 100 rotates in the direction of arrow L with a large radius of rotation to expand and excavate the ground around the pile hole H (see Figure 8), thereby achieving a higher expansion excavation rate than conventional expansion drilling devices. Furthermore, when the expansion wing 11 is in the expanded diameter state, the second drilling bit 15b contacts the hole wall, and as the expansion wing 11 penetrates the hole wall and is pulled up, the third drilling bit 15c contacts the upper surface of the hole wall, allowing the hole wall to be precisely cut and the hole to be expanded.

When the expansion blade 11 rotates in the direction of arrow L to excavate the ground, the reaction force of the earth pressure generated at the protrusion 11e is supported by the outer periphery of the drilling shaft 10 (the part where the protrusion 11e abuts), making it less susceptible to damage and providing high strength despite its simple structure. In addition, because the support shaft 13 is positioned away from the outer periphery of the drilling shaft 10, soil accumulated between the support shaft 13 and the reaction point (protrusion 11e) does not get caught when the expansion blade 11 expands, ensuring smooth expansion operation.

After the expansion drilling operation is completed, the drilling rod 1 (see Figure 8) is rotated forward in the direction of arrow R, causing the multiple expansion wings 11, which have received earth pressure, to return to the reduced diameter state shown in Figures 1 and 2, allowing the expansion drilling device 100 and drilling head 20, together with the drilling rod 1, to be easily raised to the ground.

The expansion wing 11 that makes up the expansion drilling device 100 expands or contracts in diameter simply by rotating the drilling shaft 10 in the forward or reverse direction via the drilling rod 1, so no hydraulic or electrical operating systems are required. Therefore, the expansion drilling device 100 can be constructed solely from mechanical elements, and its structure is simple.

Next, the rotation angle of the expansion wing 11 will be described with reference to FIGS. 9 and 10. FIG.
First, as a basic condition, the rotation speed of the drilling rod 1 is often in the range of 5 rpm to 25 rpm. Therefore, for example, when the expansion drilling diameter is φ1000 mm, the sliding distance of the tip 11a of the expansion wing 11 (φ1000 mm × 3.14 × rotation speed ÷ 60) is approximately 261.8 mm/s to 1309 mm/s. Furthermore, the lifting speed of the drilling rod 1 during expansion drilling work is often in the range of 0.5 m/min (8.3 mm/s) to 2.0 m/min (33.3 mm/s).

When performing expansion drilling using mechanical means with reverse rotation within the above application range, it is effective to position the second drilling bit 15b attached to the tip 11a of the expansion wing 11 in an orientation that allows it to efficiently receive the mechanical stress applied from the hole wall when cutting the hole wall. As the drilling rod 1 rotates, the second drilling bit 15b moves along side ab of the isosceles triangle shown in Figure 9. Furthermore, as the drilling rod 1 is pulled up, the second drilling bit 15b moves along side bc. As a result, the second drilling bit 15b follows the trajectory of side ac, which is the resultant vector of these.

Here, in the model case where the enlarged excavation diameter is φ1000 mm, if the rotation speed is slow (261.8 mm/s) and the lifting speed is fast (33.3 mm/s), θ ₁ = tan ^-1 (b/a) ≒ 7.3°. On the other hand, if the rotation speed is fast (1309 mm/s) and the lifting speed is slow (33.3 mm/s), θ ₂ ≒ 0.4°. Since typical enlarged excavation diameters are φ600 mm to φ2000 mm, θ is generally 0.2° to 12°. However, considering play due to mechanical tolerances, it is best to set θ between 0° and 25°.

In this embodiment, an example has been described in which the drilling rod 1 is pulled up while rotating in the reverse direction to enlarge the hole wall, but it is also possible to configure the drilling rod 1 to be pushed down while rotating in the reverse direction to enlarge the hole wall. In this case, the angle θ is reversed (-).

In the expansion drilling device 100 of this embodiment, the two support shafts 13 that rotatably support the expansion blades 11 are positioned at an angle θ with the axis 10c of the drilling shaft 10, allowing the expansion blades 11 to rotate in the direction of angle θ. This allows the expansion blades 11 to efficiently receive the mechanical stress applied by the hole wall and quickly open when the drilling rod 1 is pulled up or down while rotating in the reverse direction to perform expansion drilling of the hole wall.

In particular, when the drilling rod 1 is rotated in the reverse direction and pulled up to enlarge and drill the hole wall, the expansion blades 11 are tilted at angle θ, and gravity also acts, making it easier for the expansion blades 11 to open. Furthermore, the downward stress applied when cutting the hole wall is dispersed, improving the load-bearing capacity of the expansion blades 11.

Furthermore, as shown in Figure 10, by tilting the orientation of the second drilling bit 15b by an angle θ relative to the reverse rotation direction of the drilling rod 1, the second drilling bit 15b can move while pressing perpendicularly against the hole wall surface. As a result, when the drilling rod 1 is pulled up or down while rotating in the reverse direction to drill an enlarged hole wall, the mechanical stress applied from the hole wall is efficiently received by the second drilling bit 15b, cutting the hole wall and improving hole wall drilling efficiency. This also improves the mechanical strength of the second drilling bit 15b.

The excavation device according to the present invention can be widely used in fields such as civil engineering and construction as a device for excavating and enlarging the tip of a pile hole formed in the ground to form a root-hardening bulb.

REFERENCE SIGNS LIST 1 Drilling rod 2 Drive shaft 3 Drilling blade 4 Connector hole 10 Drilling shaft 10c Axial center 11 Expanding blade 11a Tip 11b Outer surface 11c Convex surface 11d Concave surface 11e Projection 12 Shaft 12a Flat surface 12b Arc surface 13 Support shaft 14a Connector 14b Connector hole 15a, 15b, 15c Drilling bit 16 Bracket 20 Drilling head 21 Drive shaft 22 Connector 23 Drilling blade 24 Drilling bit 100 Expanding drilling device

Claims (4)

a drilling shaft connectable to the drilling rod so as to rotate together therewith;
A plurality of support shafts are arranged on the outer periphery of the drilling shaft, parallel to the axis of the drilling shaft, and equally spaced along the circumferential direction of the drilling shaft;
expansion wings rotatably attached to the plurality of support shafts,
During pile hole excavation work in which the drilling rod rotates forward, the expansion wings, which are subjected to earth pressure, maintain a contracted diameter state,
During the enlarged excavation work in which the drilling rod rotates in the reverse direction, the expansion wing, which receives earth pressure, rotates around the support shaft, and a part of the expansion wing spreads until it abuts against the outer periphery of the drilling shaft, and maintains the expanded diameter state.
An expansion drilling device having a first drilling bit on the outer surface of the tip of the expansion wing at a position where the expansion wing comes into contact with the hole wall and generates friction when the expansion wing is in a reduced diameter state when the drilling rod starts to reverse rotate. The expansion drilling device according to claim 1, further comprising a second drilling bit at the tip of the expansion wing that contacts the hole wall in the expanded state. 3. The expansion drilling device according to claim 2, wherein the second drill bit is oriented at an upward or downward angle of 0° to 25° relative to the reverse rotation direction of the drill rod. 4. The expansion drilling device according to claim 1, wherein the expansion wing rotates in an upward or downward direction at an angle of 0° to 25° relative to the counter-rotation direction of the drilling rod.