Enlarged drilling device

Abstract

To provide an expansion drilling unit that can increase the soil pressure an expanding wing receives when a drilling rod starts the reverse rotation, and quickly opens the expanding wing to perform expansion drilling.SOLUTION: An expansion drilling unit 100 comprises a drilling shaft 10 that is connectable to a drilling rod 1 to rotate as a unified body, multiple support shafts 13 that are parallel to the shaft center axis of the drilling shaft 10 and arranged on the outer periphery of the drilling shaft 10 at equal intervals along the peripheral direction of the drilling shaft 10, and expansion wings 11 that are rotatably fitted to the support shafts 13. During a pile hole drilling work in which the drilling rod 1 makes the positive rotation, the expansion wings 11 that receive the soil pressure maintain the diameter-reduced state, while, during an expansion drilling work in which the drilling rod 1 makes the reverse rotation, the expansion wings 11 that receive the soil pressure rotate around the support shafts 13 and expand up to the state that part of the expansion wing 11 comes to contact with the outer periphery of the drilling shaft 10 to retain the diameter-increased state. The drilling shaft 10 has a shank part 12 in a shape made by trimming a cylinder, the center of which is the shaft center axis, by planes 12a, 12a that are parallel to the shaft center axis avoiding the areas where the multiple support shafts are placed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an enlargement excavation device for enlarging the tip of a pile hole formed in the ground to construct a root ball reinforcement part.

Background Art

[0002] As an enlargement excavation device for enlarging the tip of a pile hole formed in the ground to form a root ball reinforcement part, there is, for example, the enlargement excavation device described in Patent Document 1. This enlargement excavation device includes an excavation shaft that can be integrally connected to the tip of an excavation rod, a plurality of support shafts that are parallel to the axis of the excavation shaft and are arranged at equal intervals along the circumferential direction of the excavation shaft on the outer periphery of the excavation shaft, and enlargement wings that are rotatably attached to each support shaft. During the pile hole excavation operation in which the excavation rod rotates forward, the enlargement wings receiving the earth pressure maintain a reduced diameter state. During the enlargement excavation operation in which the excavation rod rotates reversely, the enlargement wings receiving the earth pressure rotate around the support shafts to become an enlarged diameter state, and in this state, the plurality of enlargement wings rotate together with the excavation shaft to enlarge and drill the surrounding ground.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the above conventional enlargement excavation device, when performing the enlargement excavation operation, the excavation rod that is rotating forward is rotated reversely so that the enlargement wings open under the earth pressure. At this time, the earth pressure received by the enlargement wings depends on the amount of excavated earth and sand existing on the outer periphery of the excavation shaft. However, when the excavation shaft is thickened to achieve a larger diameter enlargement excavation during reverse rotation, the amount of excavated earth and sand existing on the outer periphery of the excavation shaft decreases, so there is a problem that the earth pressure received by the enlargement wings decreases.

[0005] Therefore, the present invention aims to provide an enlarged drilling device that can increase the earth pressure on the expanding blades when the drilling rod starts to rotate in reverse, thereby quickly opening the expanding blades and performing enlarged drilling. [Means for solving the problem]

[0006] The present invention provides an enlarged drilling device comprising a drilling shaft that can be connected to a drilling rod so as to rotate integrally with it, a plurality of support shafts arranged on the outer circumference of the drilling shaft parallel to the axis of the drilling shaft and at equal intervals along the circumferential direction of the drilling shaft, and a plurality of enlarged blades that are rotatably attached to each of the plurality of support shafts, wherein during pile hole drilling work in which the drilling rod rotates in the forward direction, the plurality of enlarged blades that receive earth pressure maintain a reduced diameter state, and during enlarged drilling work in which the drilling rod rotates in the reverse direction, the plurality of enlarged blades that receive earth pressure rotate around the support shafts and expand until the plurality of enlarged blades contact the outer circumference of the drilling shaft and maintain an enlarged diameter state, wherein the drilling shaft has a shaft portion in which a part of the side surface of a cylinder with an axis centered on it is cut off parallel to the axis toward the plurality of enlarged blades.

[0007] According to the present invention, when the drilling rod rotates forward to perform pile hole drilling and when the drilling rod rotates backward to perform enlargement drilling, excavated soil exists in the space cut parallel to the axis toward the multiple enlargement blades on the shaft of the drilling shaft. As a result, the excavated soil in this space flows toward the enlargement blades, increasing the earth pressure received by the enlargement blades.

[0008] Here, it is desirable that the expanding wing has a convex surface that curves towards the rear in the direction of rotation as it moves away from the support shaft, and a concave surface that is continuous with the convex surface and curves towards the front in the direction of rotation, on the surface that receives earth pressure during expanding excavation when the excavation rod rotates in the reverse direction. As a result, the expanding wing has a space that can easily receive the excavated soil that flows along the plane as described above, so that the excavated soil flows smoothly towards the rear outer periphery along the convex and concave surfaces, making it possible to open the expanding wing quickly. [Effects of the Invention]

[0009] (1) The drilling shaft has a shaft section in which a part of the side surface of a cylinder centered on the axis is cut off parallel to the axis toward multiple expanding wings, thereby increasing the earth pressure received by the expanding wings and enabling the wings to open quickly to perform enlarged drilling.

[0010] (2) The expanding wing has a surface that receives earth pressure during the expansion drilling operation when the drilling rod rotates in the reverse direction, which has a convex surface that curves towards the rear in the direction of rotation as it moves away from the support shaft, and a concave surface that is continuous with the convex surface and curves towards the front in the direction of rotation. As a result, the excavated soil flows smoothly to the rear outer part along the convex and concave surfaces, making it possible to quickly open the expanding wing and perform expansion drilling. [Brief explanation of the drawing]

[0011] [Figure 1] A front view showing the expanded blade of the expanding drilling device in a reduced diameter state according to an embodiment of the present invention. [Figure 2] Figure 1 is a plan view of the enlarged drilling machine. [Figure 3] Figure 1 is a front view showing the enlarged wing of the enlarged drilling machine in its enlarged state. [Figure 4] Figure 3 is a plan view of the enlarged drilling machine. [Figure 5] This is a view from the X-arrow, with the enlarged wing in Figure 1 omitted. [Figure 6] This is a front view showing the drilling head connected to the enlarged drilling device shown in Figure 1. [Figure 7] This is a perspective view showing the drilling head connected to the enlarged drilling device shown in Figure 1. [Figure 8] Figure 1 is a vertical cross-sectional view showing the operating state of the enlarged drilling machine (with the enlarged blades in a reduced diameter state). [Figure 9] This is an explanatory diagram showing the orientation of the drilling bit at the tip of the expanding wing that cuts the hole wall when the angle of the expanding wing's support axis is 0°. [Figure 10] This is an explanatory diagram showing the orientation of the drilling bit at the tip of the expanding wing that cuts the hole wall when the angle of the expanding wing's support axis is θ. [Modes for carrying out the invention]

[0012] As shown in Figure 8, the enlargement excavation device 100 in the embodiment of the present invention is for enlarging and excavating the tip of a pile hole H formed in the ground to construct a root-reinforcement bulb (not shown). The enlargement excavation device 100 is provided at the tip of the excavation rod 1. The excavation rod 1 comprises a drive shaft 2 that is rotated in forward and reverse directions by a driving means (not shown) such as an auger machine, and a helical excavation blade 3 provided on the outer circumference of the drive shaft 2.

[0013] As shown in Figures 1 to 4, the enlargement 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 with it, two support shafts 13 provided on the outer circumference of the drilling shaft 10, and two enlargement blades 11 that are 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.

[0014] The drilling shaft 10 has a shaft portion 12 that is shaped like a cylinder with a central axis 10c, with a portion of the side surface cut off by two planes 12a, 12a. The two planes 12a, 12a are formed parallel to the axis 10c, facing the two expanding wings 11 on either side of the axis 10c, at positions that avoid the areas where each support shaft 13 is 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 is provided protruding from the upper end of the shaft portion 12 of the drilling shaft 10 for connection 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 at 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.

[0015] The two support shafts 13 form an angle θ (see Fig. 5) with the axis 10c of the excavation shaft 10 on the arc surfaces 12b, 12b of the outer periphery of the shaft portion 12 of the excavation shaft 10, and are arranged at equal intervals (180° intervals) along the circumferential direction of the excavation shaft 10. Each support shaft 13 is provided at a position separated from the arc surfaces 12b, 12b of the outer periphery of the shaft portion 12 of the excavation shaft 10 via a pair of brackets 16, 16 that are separated in a direction parallel to the axis 10c as shown in Figs. 1 and 2 and inclined at an angle θ with respect to the horizontal direction as shown in Fig. 5.

[0016] During the pile hole excavation operation in which the excavation rod 1 rotates clockwise in the direction of the arrow R, the expansion wings 11 receive earth pressure and rotate around the support shaft 13 as shown in Figs. 1 and 2, and are in a reduced diameter state accommodated within the rotation locus of the excavation blades 3. On the other hand, during the expansion excavation operation in which the excavation rod 1 rotates counterclockwise in the direction of the arrow L, the expansion wings 11 receive earth pressure and rotate around the support shaft 13, and are in an expanded diameter state protruding radially outward from the rotation locus of the excavation blades 3 as shown in Figs. 3 and 4.

[0017] On the outer surface 11b of the tip portion 11a of the expansion wing 11 in the reduced diameter state shown in Figs. 1 and 2, a first excavation bit 15a is provided at a position that first contacts the hole wall at the start of the reverse rotation of the excavation rod 1. Further, the tip portion 11a of the expansion wing 11 is provided with a second excavation bit 15b that contacts the hole wall in the expanded diameter state shown in Figs. 3 and 4. On the upper and lower surfaces of the tip portion of the expansion wing 11, a third excavation bit 15c is provided for cutting the upper and lower surfaces of the hole wall into which the expansion wing 11 has entered in the expanded diameter state of the expansion wing 11.

[0018] The expansion wing 11 has a convex surface 11c that curves toward the rear side in the direction of the arrow L as it moves away from the support shaft 13 on the front side surface in the direction of the arrow L, that is, the surface that receives earth pressure during the expansion excavation operation, and a concave surface 11d that is continuous with this convex surface 11c and curves toward the front side, that is, the opposite side in the direction of the arrow L. Further, a protruding portion 11e that protrudes in a direction away from the tip portion is provided on the base end side of the expansion wing 11. In this embodiment, the expansion wings 11 are arranged at two locations on the outer periphery of the excavation shaft 10 at 180° intervals, but the shape, number, arrangement interval, etc. of the expansion wings 11 are not limited to this embodiment.

[0019] As shown in FIGS. 6 and 7, the excavation head 20 includes a cylindrical drive shaft 21, a hexagonal columnar connector 22 protruding from the upper end side of the drive shaft 21, and spiral excavation blades 23 provided on the outer periphery of the drive shaft 21. An excavation bit 24 is provided at the tip of each excavation blade 23. By fitting the connector 22 on the upper end side of the excavation head 20 into the connector hole 14b on the lower end side of the excavation shaft 10 of the enlargement excavation device 100 and fixing it with a predetermined fixing means, the enlargement excavation device 100 and the excavation head 20 are integrally connected.

[0020] Next, the enlargement excavation device 100 integrated with the excavation head 20 is connected to the tip of the drive shaft 2 of the excavation rod 1 so as to rotate integrally with the excavation rod 1. Specifically, by fitting the connector 14a on the upper end side of the excavation shaft 10 of the enlargement excavation device 100 into the connector hole 4 (see FIG. 8) formed in the tip of the drive shaft 2 and fixing it with a predetermined fixing means, the excavation rod 1, the enlargement excavation device 100, and the excavation head 20 are integrally connected. Thereby, the enlargement excavation device 100 and the excavation head 20 are connected so as to rotate integrally with the excavation rod 1.

[0021] Next, the operation of the enlargement excavation device 100 having the above configuration will be described. As shown in FIG. 8, during the pile hole excavation operation, the excavation rod 1 is rotated forward in the direction of the arrow R. At this time, as shown in FIGS. 1 and 2, since the tip portion 11a of the expansion wing 11 receiving the earth pressure is kept in a state of approaching the excavation shaft 10, the expansion wing 11 is kept in a reduced diameter state. Therefore, by rotating the excavation rod 1 forward in the direction of the arrow R, the pile hole excavation operation can be performed smoothly.

[0022] On the other hand, during enlarged excavation, the excavation rod 1 is pulled up while rotating in the opposite direction of arrow line L. At this time, as shown in Figures 3 and 4, the multiple expanding wings 11, which are subjected to earth pressure, each rotate around the support shaft 13, causing the expanding wings 11 to expand. At this time, the first excavation bit 15a, which is provided on the outer surface 11b of the tip portion 11a of the expanding wing 11, makes contact with the hole wall first, generating friction early on and allowing the expanding wings 11 to open quickly.

[0023] Furthermore, the shaft portion 12 of the drilling shaft 10 has a shape in which a part of the side surface of a cylinder centered on the axis 10c is cut off toward the two expanding wings 11 by two planes 12a, 12a parallel to the axis 10c, flanking the axis 10c. As a result, excavated soil exists in this cut-off space, and when the drilling rod 1 rotates in the reverse direction, the excavated soil in this space flows toward the expanding wings 11, increasing the earth pressure that the expanding wings 11 receive. Note that the shaft portion 12 can also be shaped as shown by the dashed line 17 in Figure 2, with the cut-off diagonally toward the expanding wings 11 and parallel to the axis. In this case as well, when the drilling rod 1 rotates in the reverse direction, the excavated soil in this space flows toward the expanding wings 11, increasing the earth pressure that the expanding wings 11 receive.

[0024] Furthermore, the expanding wing 11 has a space formed by its convex surface 11c and concave surface 11d that is conducive to receiving excavated soil, so that the excavated soil flows smoothly along the convex surface 11c and concave surface 11d toward the rear outer perimeter, allowing the expanding wing to open quickly.

[0025] In this way, the expanding wing 11 expands until the projection 11e contacts the outer circumference of the drilling shaft 10, and is maintained in the expanded diameter state shown in Figures 3 and 4. Then, the second drilling bits 15b and third drilling bits 15c of the multiple expanding wings 11, which are pulled up while rotating in the opposite direction in the arrow line L with a larger turning radius than the drilling blade 23 (see Figure 8), excavate the ground around the expanding wing 11 that has formed the pile hole H in the ground as shown in Figure 8, and a root-reinforcement bulb (not shown) with an inner diameter larger than that of the pile hole H is formed.

[0026] The expanding blades 11 of the expanding drilling device 100 rotate in the direction of arrow L with a large radius of rotation to enlarge and excavate the ground around the pile hole H (see Figure 8), thus increasing the enlargement drilling rate compared to conventional expanding drilling devices. Furthermore, when the expanding blades 11 are in the enlarged state, the second drilling bit 15b contacts the hole wall, and as the expanding blades 11 enter the hole wall and are pulled up, the third drilling bit 15c contacts the upper surface of the hole wall, allowing for precise cutting of the hole wall and enlargement drilling.

[0027] Furthermore, when the expanding wing 11 rotates in the direction of arrow L to excavate the ground, the reaction force of the earth pressure generated on the projection 11e is supported by the outer circumference of the excavation shaft 10 (the part in contact with the projection 11e), making it less susceptible to damage and providing high strength despite its simple structure. In addition, since the support shaft 13 is positioned away from the outer circumference of the excavation shaft 10, soil and sand accumulated between the support shaft 13 and the reaction point (projection 11e) do not get caught when the expanding wing 11 expands, ensuring smooth expansion.

[0028] After the enlargement excavation work is completed, when the excavation rod 1 (see Figure 8) is rotated in the direction of arrow R, the multiple enlargement wings 11 that have been subjected to earth pressure return to the reduced diameter state shown in Figures 1 and 2, so that the enlargement excavation device 100 and the excavation head 20 can be easily lifted to the ground together with the excavation rod 1.

[0029] The expanding blades 11 of the expanding drilling device 100 expand or contract in diameter simply by rotating the drilling shaft 10 in the forward or reverse direction via the drilling rod 1, thus eliminating the need for hydraulic or electrical operating systems. For this reason, the expanding drilling device 100 can be constructed using only mechanical elements, resulting in a simple structure.

[0030] Next, the rotation angle of the enlarged wing 11 will be explained with reference to Figures 9 and 10. First, as a basic condition, the rotational speed of the drilling rod 1 is often set in the range of 5 rpm to 25 rpm. Therefore, for example, if the enlarged drilling diameter is φ1000 mm, the sliding distance of the tip 11a of the enlargement wing 11 (φ1000 mm × 3.14 × rotational speed ÷ 60) will be approximately 261.8 mm / s to 1309 mm / s. In addition, the lifting speed of the drilling rod 1 during enlarged drilling is often set in the range of 0.5 m / min (8.3 mm / s) to 2.0 m / min (33.3 mm / s).

[0031] Within the scope of application described above, when enlarging the borehole by mechanical means using reverse rotation, it is effective to position the second drilling bit 15b, which is provided at the tip 11a of the enlarging wing 11, in a direction that efficiently receives the mechanical stress applied from the borehole wall, thereby cutting the borehole wall. As the drilling rod 1 rotates, the second drilling bit 15b moves along side ab of the isosceles triangle shown in Figure 9. Also, 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 combined vector of these two sides.

[0032] In this model case where the enlarged drilling diameter is φ1000mm, if the rotation speed is slow (261.8mm / s) and the lifting speed is fast (33.3mm / s), then θ1 = tan -1 (b / a) ≈ 7.3°. On the other hand, when the rotation speed is fast (1309 mm / s) and the lifting speed is slow (33.3 mm / s), θ2 ≈ 0.4°. Since the typical enlarged drilling diameter is φ600 mm to φ2000 mm, θ is generally 0.2° to 12°. However, considering the play due to mechanical tolerances, it is best to set θ to 0° to 25°.

[0033] In this embodiment, an example was described in which the borehole wall is enlarged by pulling up the drilling rod 1 while rotating it in the reverse direction. However, it is also possible to configure the borehole wall to be enlarged by pushing down the drilling rod 1 while rotating it in the reverse direction. In this case, the angle θ will be reversed (-).

[0034] In the enlargement drilling device 100 of this embodiment, the two support shafts 13 that rotatably support the enlargement blades 11 are arranged to form an angle θ with the axis 10c of the drilling shaft 10, thereby allowing the enlargement blades 11 to rotate in the direction of angle θ. This makes it possible to efficiently receive the mechanical stress applied from the borehole wall on the enlargement blades 11 when enlarging the borehole wall by pulling up or pushing down while rotating the drilling rod 1 in the reverse direction, and to quickly open the enlargement blades 11.

[0035] In particular, when the drilling rod 1 is pulled up while rotating in the reverse direction to enlarge the borehole wall, the expansion wings 11 are tilted at an angle θ, and gravity also acts on them, making it easier for the expansion wings 11 to open further. Additionally, the downward stress applied when cutting the borehole wall is distributed, improving the load-bearing capacity of the expansion wings 11.

[0036] Furthermore, as shown in Figure 10, by tilting the orientation of the second drilling bit 15b by an angle θ with respect to the reverse rotation direction of the drilling rod 1, the second drilling bit 15b can move while pressing against the borehole wall surface at a right angle. As a result, when expanding the borehole wall by pulling up or pushing down while rotating the drilling rod 1 in reverse, the mechanical stress applied from the borehole wall is efficiently received by the second drilling bit 15b, thereby cutting the borehole wall and improving the borehole wall drilling efficiency. In addition, the mechanical strength preservation of the second drilling bit 15b is improved. [Industrial applicability]

[0037] The enlargement excavation device according to the present invention can be widely used in fields such as civil engineering and construction as a device for carrying out construction work to enlarge the tip of a pile hole formed in the ground and form a root-reinforcement bulb. [Explanation of Symbols]

[0038] 1. Excavation Rod 2 drive shafts 3. Excavation blades 4 connector holes 10 Drilling shafts 10c axis center 11. Extended Wing 11a Tip 11b External surface 11c Convex 11d concave 11e Protrusion 12 Shaft section 12a plane 12b Circular arc surface 13 Spindle 14a connector 14b Connector hole 15a, 15b, 15c drilling bits 16 brackets 20 drilling heads 21 Drive shaft 22 connectors 23 Excavation blades 24 drilling bits 100 Enlarged drilling device

Claims

[Claim 1] A drilling shaft that can be connected to the drilling rod so as to rotate integrally with it, Multiple support shafts are arranged on the outer circumference of the drilling shaft, parallel to the axis of the drilling shaft, and at equal intervals along the circumferential direction of the drilling shaft. The system comprises a plurality of expanding wings, each rotatably attached to the plurality of support shafts, During pile hole drilling operations in which the drilling rod rotates in the forward direction, the multiple expanding blades, which are subjected to earth pressure, maintain their reduced diameter state. In an enlarged excavation device, during an enlarged excavation operation in which the excavation rod rotates in the reverse direction, the plurality of enlarged wings, under the influence of earth pressure, rotate around the support shaft and expand until the plurality of enlarged wings contact the outer circumference of the excavation shaft, thereby maintaining an enlarged diameter state. The drilling shaft has a shaft portion shaped by cutting off a portion of the side surface of a cylinder centered on the axis with a plane parallel to the axis toward the plurality of expanding wings. During the expansion drilling operation in which the drilling rod rotates in the reverse direction, the excavated soil present in the space cut off by the plane flows toward the expanding wings, increasing the earth pressure experienced by the expanding wings. An enlarged drilling device characterized by the following features.

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