Expansion drilling unit

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 soil 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 soil 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, an object of the present invention is to provide an enlarged excavation device capable of increasing the earth pressure received by the expanding wings when the excavation rod starts to rotate in the reverse direction, quickly opening the expanding wings, and performing enlarged hole excavation.

Means for Solving the Problems

[0006] The enlarged excavation device of the present invention includes an excavation shaft that can be connected to rotate integrally with the excavation rod, a plurality of support shafts that are parallel to the axis of the excavation shaft on the outer periphery of the excavation shaft and are arranged at equal intervals along the circumferential direction of the excavation shaft, and a plurality of expanding wings that are rotatably attached to the plurality of support shafts respectively. During the pile hole excavation operation when the excavation rod rotates forward, the plurality of expanding wings receiving the earth pressure maintain a reduced diameter state. During the enlarged excavation operation when the excavation rod rotates in the reverse direction, the plurality of expanding wings receiving the earth pressure rotate around the support shafts and expand until they contact the outer periphery of the excavation shaft, maintaining an enlarged diameter state. The excavation shaft has a shaft portion with a shape in which a part of the side surface of a cylinder centered on the axis is cut off parallel to the axis toward the plurality of expanding wings.

[0007] According to the enlarged excavation device of the present invention, when the excavation rod rotates forward to perform pile hole excavation work and rotates in the reverse direction to perform enlarged excavation work, since the excavated soil and sand exist in the space cut off parallel to the axis toward the plurality of expanding wings of the shaft portion of the excavation shaft, the excavated soil and sand in this space flows toward the expanding wings, and the earth pressure received by the expanding wings can be increased.

[0008] Here, it is desirable that the surface of the expanding wing that receives the earth pressure during the enlarged excavation operation when the excavation rod rotates in the reverse direction has a convex surface that curves toward the rear side in the rotation direction as it moves away from the support shaft, and a concave surface that is continuous with the convex surface and curves toward the front side in the rotation direction. Thereby, since a space that easily receives the excavated soil and sand flowing along the plane as described above is formed on the expanding wing, the excavated soil and sand smoothly flow along the convex surface and the concave surface to the rear outer peripheral portion, and the expanding wing can be quickly opened.

Effects of the Invention

[0009] (1) The excavation shaft has a shaft portion formed by cutting off a part of the side surface of a cylinder centered on the axis parallel to the axis toward a plurality of expansion wings, increasing the earth pressure received by the expansion wings and enabling the expansion wings to be quickly opened to perform an enlarged boring operation.

[0010] (2) When the expansion wings receive earth pressure during the enlarged excavation operation in which the excavation rod rotates reversely, the surface that receives the earth pressure has a convex surface that curves toward the rear side in the rotation direction as it moves away from the support shaft, and a concave surface that is continuous with the convex surface and curves toward the front side in the rotation direction. As a result, the excavated earth and sand smoothly flows along the convex surface and the concave surface to the outer peripheral rear part, and it becomes possible to quickly open the expansion wings to perform an enlarged boring operation.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

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Figure 8

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Figure 10

Best Mode for Carrying Out the Invention

[0012] As shown in FIG. 8, the enlarged excavation device 100 in the embodiment of the present invention is for enlarging the tip of a pile hole H formed in the ground to construct an anchoring spherical root part (not shown). The enlarged excavation device 100 is provided at the tip of the excavation rod 1. The excavation rod 1 includes a drive shaft 2 that is rotationally driven in the forward and reverse directions by a drive means (not shown) such as an auger machine, and a spiral excavation blade 3 provided on the outer periphery of the drive shaft 2.

[0013] As shown in FIGS. 1 to 4, the enlarged excavation device 100 includes an excavation shaft 10 that can be connected to rotate integrally with the excavation rod 1 (see FIG. 8), two support shafts 13 provided on the outer periphery of the excavation shaft 10, and two expansion wings 11 rotatably attached to each support shaft 13. An excavation head 20 is connected to the lower end side of the excavation shaft 10 as shown in FIGS. 5 and 6.

[0014] The excavation shaft 10 has a shaft portion 12 in a shape where a part of the side surface of a cylinder centered on the axis 10c is cut off by two planes 12a, 12a. The two planes 12a, 12a are formed parallel to the axis 10c toward each of the two expansion wings 11 with the axis 10c in between, avoiding the portions where the respective support shafts 13 are arranged. The excavation shaft 10 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. A hexagonal column-shaped connector 14a for connecting to the lower end portion of the drive shaft 2 of the excavation rod 1 protrudes from the upper end side of the shaft portion 12 of the excavation shaft 10. A connector hole 14b into which a connector 22 (see FIG. 6) protruding from the upper end side of the drive shaft 21 of the excavation head 20 can be inserted is bored in the direction of the axis 10c on the lower end side of the shaft portion 12 of the excavation shaft 10.

[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. As shown in Figs. 1 and 2, each support shaft 13 is provided at a position away from the arc surfaces 12b, 12b of the outer periphery of the shaft portion 12 of the excavation shaft 10 through a pair of brackets 16, 16 that are separated in a direction parallel to the axis 10c and inclined at an angle θ with respect to the horizontal direction as shown in Fig. 5.

[0016] During the pile hole excavation operation when the excavation rod 1 rotates clockwise in the direction of the arrow R, the expansion wing 11 receives the earth pressure and rotates around the support shaft 13 as shown in Figs. 1 and 2, and enters a reduced diameter state accommodated within the rotation locus of the excavation blade 3. On the other hand, during the expansion excavation operation when the excavation rod 1 rotates counterclockwise in the direction of the arrow L, the expansion wing 11 receives the earth pressure and rotates around the support shaft 13, and enters an expanded diameter state protruding radially outward from the rotation locus of the excavation blade 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 the position that first contacts the hole wall at the start of the counterclockwise 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 the 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 protrusion 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 at 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 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 arrow R, the pile hole excavation operation can be smoothly performed.

[0022] On the other hand, during the enlargement excavation operation, the excavation rod 1 is pulled up while rotating counterclockwise in the direction of the arrow L. At this time, as shown in FIGS. 3 and 4, a plurality of enlargement wings 11 receiving earth pressure rotate around the support shafts 13 respectively, and the enlargement wings 11 expand. At this time, the first excavation bit 15a provided on the outer surface 11b of the tip portion 11a of the enlargement wing 11 first contacts the hole wall, thereby generating friction early and enabling the enlargement wing 11 to open quickly.

[0023] In addition, since the shaft portion 12 of the excavation shaft 1 has a shape in which a part of the side surface of a cylinder centered on the axis 10c is cut off by two planes 12a, 12a parallel to the axis 10c with the axis 10c sandwiched therebetween toward the two enlargement wings 11, excavated soil and sand exist in this cut-off space. When the excavation rod 1 rotates counterclockwise, the excavated soil and sand in this space flow toward the enlargement wing 11, and the earth pressure received by the enlargement wing 11 can be increased. Note that the shaft portion 12 may also have a shape cut off obliquely toward the enlargement wing 11 and parallel to the axis as shown by the broken line 17 in FIG. 2. Also in this case, when the excavation rod 1 rotates counterclockwise, the excavated soil and sand in this space flow toward the enlargement wing 11, and the earth pressure received by the enlargement wing 11 can be increased.

[0024] In addition, since a space that easily receives excavated soil and sand is formed on the convex surface 11c and the concave surface 11d of the enlargement wing 11, the excavated soil and sand smoothly flow along the convex surface 11c and the concave surface 11d toward the rear outer peripheral portion, and the enlargement wing can be opened quickly.

[0025] In this way, the enlargement wing 11 expands until the protrusion 11e abuts against the outer periphery of the excavation shaft 1, and is maintained in the enlarged diameter state shown in FIGS. 3 and 4. Then, the ground around the enlargement wing 11 of the pile hole H formed in the ground shown in FIG. 8 is enlarged and excavated by the second excavation bit 15b and the third excavation bit 15c of the plurality of enlargement wings 11 that are pulled up while rotating counterclockwise in the direction of the arrow L along a larger turning radius than the excavation blade 23 (see FIG. 8), and a root fixing spherical root portion (not shown) having a larger inner diameter than the pile hole H is formed.

[0026] Since the expanding wings 11 of the expanding excavation device 100 rotate in the direction of the arrow L with a large turning radius to expand and excavate the ground around the pile hole H (see Fig. 8), the expanding excavation rate can be increased compared to conventional expanding excavation devices. Further, in the diameter-expanded state of the expanding wings 11, the second excavation bit 15b contacts the hole wall, and the expanding wings 11 enter and are pulled up on the hole wall, so that the third excavation bit 15c contacts the upper surface of the hole wall. Therefore, the hole wall can be accurately cut to perform an expanded hole cutting operation.

[0027] In addition, when the expanding wings 11 rotate in the direction of the arrow L to excavate the ground, the reaction force of the earth pressure generated in the protrusions 11e is supported by the outer periphery of the excavation shaft 10 (the portion where the protrusions 11e are in contact). Therefore, it is not easily damaged and exhibits high strength while having a simple structure. Further, since the support shaft 13 is arranged at a position away from the outer periphery of the excavation shaft 10, the earth and sand accumulated between the support shaft 13 and the reaction point (protrusions 11e) will not be bitten when the expanding wings 11 expand in diameter, and a smooth diameter-expanding operation can be ensured.

[0028] After the expanding excavation work is completed, when the excavation rod 1 (see Fig. 8) is rotated forward in the direction of the arrow R, the plurality of expanding wings 11 that have received the earth pressure return to the diameter-reduced state shown in Figs. 1 and 2 respectively. Therefore, the expanding excavation device 100 and the excavation head 20 can be easily pulled up to the ground together with the excavation rod 1.

[0029] The expanding wings 11 that make up the expanding excavation device 100 expand or contract in diameter simply by rotating the excavation shaft 10 forward or backward via the excavation rod 1. Therefore, a hydraulic or electrical operation system is unnecessary. For this reason, the expanding excavation device 100 can be composed of only mechanical elements and has a simple structure.

[0030] Next, the rotation angle of the expanding wings 11 will be described with reference to Figs. 9 and 10. First, as a basic condition, the rotation speed of the drilling rod 1 is often applied in the range of 5 rpm to 25 rpm. Therefore, for example, when the enlarged drilling diameter is φ1000 mm, the sliding distance of the tip 11a of the enlarged wing 11 (φ1000 mm × 3.14 × rotation speed ÷ 60) is about 261.8 mm / s to 1309 mm / s. Also, the pulling-up speed of the drilling rod 1 during the enlarged drilling operation is often applied in the range of 0.5 m / min (8.3 mm / s) to 2.0 m / min (33.3 mm / s).

[0031] In the above application range, when performing enlarged drilling by mechanical means with reverse rotation, it is effective to arrange the second drilling bit 15b provided at the tip 11a of the enlarged wing 11 in a direction that can efficiently receive the mechanical stress applied from the hole wall and cut the hole wall. As the drilling rod 1 rotates, the second drilling bit 15b moves along side ab of the isosceles triangle shown in FIG. 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 locus of side ac, which is the resultant vector of these.

[0032] Here, in the model case where the enlarged drilling diameter is φ1000 mm, when the rotation speed is slow (261.8 mm / s) and the pulling-up speed is fast (33.3 mm / s), θ 1 =tan -1 (b / a)≒7.3°. On the other hand, when the rotation speed is fast (1309 mm / s) and the pulling-up speed is slow (33.3 mm / s), θ 2 ≒0.4°. Since the general 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 better to set θ to 0° to 25°.

[0033] In this embodiment, an example of enlarging the hole wall by pulling up the drilling rod 1 while rotating it in reverse has been described. Conversely, it is also possible to adopt a configuration in which the hole wall is enlarged by pushing down the drilling rod 1 while rotating it in reverse. In this case, the angle θ becomes negative ( - ).

[0034] In the enlarging excavation device 100 according to the present embodiment, two support shafts 13 that rotatably support the enlarging blades 11 are arranged at an angle θ with respect to the axis 10c of the excavation shaft 10, so that the enlarging blades 11 rotate in the direction of the angle θ. As a result, when the excavation rod 1 is pulled up or pushed down while rotating in the reverse direction to enlarge the excavation of the hole wall, the mechanical stress applied from the hole wall can be efficiently received by the enlarging blades 11, enabling the enlarging blades 11 to open quickly.

[0035] In particular, when the excavation rod 1 is pulled up while rotating in the reverse direction to enlarge the excavation of the hole wall, since the enlarging blades 11 are inclined at an angle θ, gravity also acts, making it easier for the enlarging blades 11 to open. Also, when cutting the hole wall, the stress applied downward is dispersed, improving the load-bearing capacity of the enlarging blades 11.

[0036] Also, as shown in FIG. 10, by tilting the direction of the second excavation bit 15b by an angle θ with respect to the reverse rotation direction of the excavation rod 1, the second excavation bit 15b can move while being in pressure contact with the hole wall surface at a right angle. As a result, when the excavation rod 1 is pulled up or pushed down while rotating in the reverse direction to enlarge the excavation of the hole wall, the mechanical stress applied from the hole wall can be efficiently received by the second excavation bit 15b, and by cutting the hole wall, the hole wall excavation efficiency is improved. Also, the preservation of the mechanical strength of the second excavation bit 15b is improved.

Industrial Applicability

[0037] The enlarging excavation device according to the present invention can be widely used in fields such as civil engineering and construction as a device for constructing a project to enlarge the tip of a pile hole formed in the ground to form a root fixing spherical part.

Explanation of Reference Numerals

[0038] 1 Excavation rod 2 Drive shaft 3 Excavation blades 4 Connector hole 10 Excavation shaft 10c Axis 11 Enlarging blades 11a Tip 11b Outer surface 11c Convex surface 11d Concave surface 11e Protrusion 12 Shaft portion 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 Enlarged drilling device

Claims

1. 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; a plurality of expansion wings rotatably attached to the plurality of support shafts, During pile hole excavation work in which the drilling rod rotates forward, the plurality of expansion wings subjected to earth pressure maintain a contracted state, During the enlarged excavation work in which the drilling rod rotates in the reverse direction, the plurality of expansion wings that receive earth pressure rotate around the support shaft, and the plurality of expansion wings spread out until they abut against the outer periphery of the drilling shaft, and maintain the expanded diameter state. The drilling shaft has a shaft portion having a shape in which a part of a side surface of a cylinder centered on the axis is cut off parallel to the axis toward the plurality of expansion wings. Expanded drilling rig.

2. The expansion excavation device according to claim 1, wherein the multiple expansion wings have a surface that receives earth pressure during an expansion excavation operation in which the drilling rod rotates in the reverse direction, the surface having a convex surface that curves toward the rear side in the rotational direction as it moves away from the support shaft, and a concave surface that is continuous with the convex surface and curves toward the front side in the rotational direction.

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