Expansion drilling unit

Abstract

To provide an expansion drilling unit that can perform expanded boring with an expanding wing readily opened when a drilling rod starts the reverse rotation.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 expansion wing 11 comprises, on the outer face of its tip, a first drilling bit 15a arranged at a position to touch the bore wall in the first place when the drilling rod 1 starts the reverse rotation.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] As an enlargement excavation device for enlarging and excavating the tip of a pile hole formed in the ground to form a root ball foundation 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 on the outer periphery of the excavation shaft and are arranged at equal intervals along the circumferential direction of the excavation shaft, and enlargement wings 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. However, when the excavation rod starts to rotate reversely, the enlargement wings are in a closed state, so even if they come into contact with the hole wall surface, the frictional force is small and they tend to slide on the hole wall surface. Therefore, a time loss occurs from when the reverse rotation starts until the enlargement wings start to open.

[0005] Therefore, an object of the present invention is to provide an enlarged excavation device capable of quickly opening an enlarged wing and performing enlarged hole excavation when the excavation rod starts to rotate reversely.

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 an enlarged wing rotatably attached to each of the plurality of support shafts. During the pile hole excavation operation when the excavation rod rotates forward, the enlarged wing under earth pressure maintains a reduced diameter state. During the enlarged excavation operation when the excavation rod rotates reversely, the enlarged wing under earth pressure rotates around the support shaft and expands until a part of the enlarged wing abuts against the outer periphery of the excavation shaft to maintain an enlarged diameter state. It is an enlarged excavation device provided with a first excavation bit at a position on the outer side surface of the tip of the enlarged wing that first contacts the hole wall when the reverse rotation of the excavation rod starts.

[0007] According to the enlarged excavation device of the present invention, when the excavation rod rotates forward to perform pile hole excavation work and the excavation rod rotates reversely to perform enlarged excavation work, the first excavation bit provided on the outer side surface of the tip of the enlarged wing first contacts the hole wall, causing friction early and enabling the enlarged wing to be quickly opened.

[0008] It is desirable that the enlarged excavation device of the present invention is provided with a second excavation bit that contacts the hole wall in the enlarged diameter state at the tip of the enlarged wing. Thereby, the second excavation bit can contact the hole wall in the enlarged diameter state of the enlarged wing, enabling accurate cutting of the hole wall.

[0009] Here, it is desirable that the direction of the second excavation bit is such that the angle with respect to the reverse rotation direction of the excavation rod is 0° to 25°, more preferably 0.2° to 12°. Thereby, when expanding and excavating the hole wall by pulling up or pushing down while rotating the excavation rod reversely, the mechanical stress applied from the hole wall can be efficiently received by the second excavation bit to cut the hole wall.

[0010] Also, it is desirable that the expansion wing rotates in a direction where the angle with respect to the reverse rotation direction of the drilling rod is 0° to 25°, more preferably 0.2° to 12°. Thereby, when expanding and excavating the hole wall by pulling up or pushing down while reverse-rotating the drilling rod, the mechanical stress applied from the hole wall can be efficiently received by the expansion wing, enabling the expansion wing to open quickly. In particular, when expanding and excavating the hole wall by pulling up while reverse-rotating the drilling rod, the inclination of the expansion wing causes gravity to act, making it easier for the expansion wing to open further. Also, when cutting the hole wall, the downward-applied stress is dispersed.

Advantages of the Invention

[0011] (1) With a configuration in which a first drilling bit is provided on the outer surface of the tip of the expansion wing at a position that first contacts the hole wall at the start of reverse rotation of the drilling rod, it becomes possible to quickly open the expansion wing and perform enlarged hole drilling.

[0012] (2) By providing a second drilling bit that contacts the hole wall in the expanded diameter state at the tip of the expansion wing, it becomes possible to accurately cut the hole wall with the second drilling bit in the expanded diameter state of the expansion wing and perform enlarged hole drilling.

[0013] (3) Since the direction of the second drilling bit is such that the angle with respect to the reverse rotation direction of the drilling rod is 0° to 25°, more preferably 0.2° to 12°, when expanding and excavating the hole wall by pulling up or pushing down while reverse-rotating the drilling rod, the mechanical stress applied from the hole wall can be efficiently received by the second drilling bit, and by cutting the hole wall, the hole wall excavation efficiency is improved. Also, the preservation of the mechanical strength of the second drilling bit is improved.

[0014] (4) The expanding wings rotate in a direction where the angle with respect to the reverse rotation direction of the drilling rod is between 0° and 25°. When expanding and excavating the hole wall by pulling up or pushing down the drilling rod while rotating it in the reverse direction, the mechanical stress applied from the hole wall can be efficiently received by the expanding wings, enabling the expanding wings to quickly open and perform the expanding excavation. In particular, when expanding and excavating the hole wall by pulling up the drilling rod while rotating it in the reverse direction, the inclination of the expanding wings causes gravity to act, making it easier for the expanding wings to open further. Also, when cutting the hole wall, the stress applied downward is dispersed, improving the load-bearing capacity of the expanding wings.

Brief Description of the Drawings

[0015]

Figure 1

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Embodiments for Carrying Out the Invention

[0016] 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 a root fixing 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.

[0017] 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 enlarged 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.

[0018] 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 enlarged 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 columnar 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.

[0019] 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 separated 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.

[0020] During the pile hole excavation operation in which the excavation rod 1 rotates forward in the direction of the arrow R, the expansion wing 11 receives earth pressure and rotates around the support shaft 13 as shown in Figs. 1 and 2, and is in a reduced diameter state accommodated within the rotation locus of the excavation blade 3. On the other hand, during the expansion excavation operation in which the excavation rod 1 rotates reversely in the direction of the arrow L, the expansion wing 11 receives earth pressure and rotates around the support shaft 13, and is in an expanded diameter state protruding radially outward from the rotation locus of the excavation blade 3 as shown in Figs. 3 and 4.

[0021] 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.

[0022] 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 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.

[0023] 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 enlarged excavation device 100 and fixing it with a predetermined fixing means, the enlarged excavation device 100 and the excavation head 20 are integrally connected.

[0024] Next, the enlarged 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 enlarged 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 enlarged excavation device 100, and the excavation head 20 are integrally connected. Thereby, the enlarged excavation device 100 and the excavation head 20 are connected so as to rotate integrally with the excavation rod 1.

[0025] Next, the operation of the enlarged 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.

[0026] On the one hand, during the enlarged excavation operation, the excavation rod 1 is pulled up while rotating in the reverse direction along the arrow L direction. At this time, as shown in FIGS. 3 and 4, a plurality of enlarged wings 11 receiving earth pressure rotate around the support shaft 13 respectively, and the enlarged wings 11 expand. At this time, the first excavation bit 15a provided on the outer surface 11b of the tip portion 11a of the enlarged wing 11 first contacts the hole wall, thereby generating friction early and enabling the enlarged wing 11 to open quickly.

[0027] In addition, since the shaft portion 12 of the excavation shaft 10 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 interposed therebetween toward the two enlarged wings 11, excavated soil and sand exist in this cut-off space. When the excavation rod 1 rotates in the reverse direction, the excavated soil and sand in this space flow toward the enlarged wing 11, and the earth pressure received by the enlarged wing 11 can be increased. Note that the shaft portion 12 may also have a shape in which it is cut off obliquely toward the enlarged 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 in the reverse direction, the excavated soil and sand in this space flow toward the enlarged wing 11, and the earth pressure received by the enlarged wing 11 can be increased.

[0028] 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 enlarged 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 enlarged wing can be opened quickly.

[0029] In this way, the enlarged wing 11 expands until the protrusion 11e abuts against the outer periphery of the excavation shaft 10 and is maintained in the enlarged diameter state shown in FIGS. 3 and 4. Then, the ground around the enlarged 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 enlarged wings 11 that are pulled up while rotating in the reverse direction along the arrow L direction while drawing a larger turning radius than the excavation blade 23 (see FIG. 8), and a root fixing spherical portion (not shown) having a larger inner diameter than the pile hole H is formed.

[0030] The expanding wing 11 of the expanding excavation device 100 rotates 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), so the expanding excavation rate can be increased compared with the conventional expanding excavation device. Further, in the expanded diameter state of the expanding wing 11, the second excavation bit 15b contacts the hole wall, and the expanding wing 11 enters and is pulled up into 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.

[0031] In addition, when the expanding wing 11 rotates in the direction of the arrow L to excavate the ground, the reaction force of the earth pressure generated on the protruding portion 11e is supported by the outer periphery of the excavation shaft 10 (the portion where the protruding portion 11e abuts). 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 (the protruding portion 11e) will not be caught when the expanding wing 11 expands in diameter, and a smooth diameter expansion operation can be ensured.

[0032] 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 reduced diameter 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.

[0033] The expanding wing 11 constituting the expanding excavation device 100 expands or contracts in diameter only by rotating the excavation shaft 10 forward or backward through the excavation rod 1, so a hydraulic or electric operation system is unnecessary. For this reason, the expanding excavation device 100 can be composed of only mechanical elements and has a simple structure.

[0034] Next, the rotation angle of the expanding wing 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).

[0035] In the above application range, when performing enlarged drilling by mechanical means with reverse rotation, the second drilling bit 15b provided at the tip 11a of the enlarged wing 11 is arranged in a direction that can efficiently receive the mechanical stress applied from the hole wall to cut the hole wall, which is effective. Due to the rotation of the drilling rod 1, the second drilling bit 15b moves along side ab of the isosceles triangle shown in Fig. 9. Also, due to the pulling-up of the drilling rod 1, 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.

[0036] 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°.

[0037] In addition, 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 ( - ).

[0038] In the enlarging excavation device 100 according to the present embodiment, two support shafts 13 that rotatably support the enlarging wings 11 are arranged at an angle θ with respect to the axis 10c of the excavation shaft 10, so that the enlarging wings 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 wings 11, and the enlarging wings 11 can be quickly opened.

[0039] 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 wings 11 are inclined at an angle θ and gravity also acts, the enlarging wings 11 are more likely to open. Also, when cutting the hole wall, the stress applied downward is dispersed, so the load-bearing capacity of the enlarging wings 11 is also improved.

[0040] Also, as shown in FIG. 10, by inclining 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 in pressure contact perpendicular to the hole wall surface. 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 the hole wall is cut, thereby improving the hole wall excavation efficiency. Also, the preservation of the mechanical strength of the second excavation bit 15b is improved.

Industrial Applicability

[0041] 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 work for enlarging the tip of a pile hole formed in the ground to form a root fixing spherical part.

Explanation of Reference Numerals

[0042] 1 Excavation rod 2 Drive shaft 3 Excavation blades 4 Connector hole 10 Excavation shaft 10c Axis 11 Enlarging wings 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; and an expansion wing rotatably attached to each of the plurality of support shafts, During pile hole excavation work in which the drilling rod rotates forward, the expansion wing receives earth pressure and maintains a contracted state, During the enlarged excavation work in which the drilling rod rotates in the reverse direction, the enlargement wing rotates around the support shaft under soil pressure, and a part of the enlargement 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 that will first contact the hole wall when the drilling rod starts to rotate in reverse.

2. 2. The expansion drilling device according to claim 1, further comprising a second drilling bit at a tip of the expansion wing, the second drilling bit contacting the hole wall in the expanded diameter state.

3. 3. The expansion drilling device according to claim 2, wherein the orientation of the second drilling bit is at an angle of 0° to 25° with respect to the reverse rotation direction of the drilling rod.

4. 4. The expansion drilling device according to claim 1, wherein the expansion wing rotates at an angle of 0° to 25° with respect to the reverse rotation direction of the drilling rod.

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