JP2711236B2 - Enlarged hole drilling head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head for drilling an enlarged hole, and more particularly to a head of an underground hole drilling device for constructing a foundation steel pipe pile or a concrete pile having a bulb portion in civil engineering work.

[0002]

2. Description of the Related Art Generally, in order to construct a foundation steel pipe pile or a concrete pile, an underground hole is excavated with an earth drill, a screw auger or the like. Then, in order to increase the bearing capacity of the foundation pile, the lower end of the foundation pile is widened in a bulb shape. For this purpose, the bottom of the underground hole is excavated at a required depth.

As an apparatus for excavating the bottom of a hole with a diameter, there is, for example, an "extended hole excavating apparatus" disclosed in Japanese Utility Model Laid-Open No. 1-75194. In this enlarged hole drilling device, a bit body having drilling blades mounted on the outer periphery is rotatably mounted on a lower end of a joint rod by a predetermined angle, and an intermediate portion is rotated by a predetermined angle on a pivot supported on upper and lower brackets on the outer circumference of the bit body. An enlarged blade freely attached is provided, and a pressing knock is provided in which a distal end portion protrudes toward a rear end portion of the enlarged blade and a base end portion is fixed to an outer periphery of the joint rod. After restricting the rotation, the excavating rod is reversed, the tip of the pressing knock is protruded toward the rear end of the magnifying blade and pressed, thereby forcibly rotating the magnifying blade outward, The excavation is expanded by the enlarged blade.

[0004]

However, according to the conventional enlarged hole drilling apparatus, the enlarged blade holds the excavating rod so as not to expand outward due to the earth pressure when the excavating rod is rotating forward. By rotating the drilling rod in the reverse direction, the drilling rod is forcibly rotated to expand outward. Therefore, the operation must be changed from forward rotation to reverse rotation to excavate the enlarged hole.

[0005] Even if the expanding blade can excavate the ground by the reverse rotation, the excavating blades bite into the ground and the rotation is restricted, so that the bottom of the hole cannot be excavated, so that the enlarged hole is formed deeper. Can not do. Even if the excavating blade is rotated together with the excavating rod in the reverse rotation, the excavating blade rotates in the opposite direction, so that the ability to excavate the bottom of the hole is extremely low, so that the work efficiency is significantly reduced.

Further, since there is no means for locking the enlarged blade at the time of forward rotation of the excavating rod, rocks or the like enter between the pressing knocks at the time of forward rotation and rotate the enlarged blade to inadvertently increase the diameter of the enlarged hole. There is no danger of excavation.

Accordingly, the present invention can be performed by excavating an enlarged hole with a forward rotation, so that the enlarged hole can be formed at a desired depth and also prevent the inflatable blade from being inadvertently expanded during the forward rotation. Provided is an enlarged hole drilling head.

[0008]

According to the present invention, there is provided a head for excavating an enlarged hole, wherein a coupling portion of a drive shaft is formed at an upper end portion, and a keyway is formed at a lower end portion in an axial direction which is diametrically opposed to each other. An outer cylinder having a key portion on the inner peripheral surface for loosely fitting and engaging with the key groove and having an excavating blade provided on the outer peripheral surface is inserted, and at least two diametrically opposed outer cylinders are inserted into the outer cylinder. At each of the two positions, the expanding blade is rotatably supported within a predetermined angle, and is engaged with the expanding blade to hold the expanding blade in a folded state within the maximum radius of the excavating blade when the shaft is normally rotated. In addition, a kick pin is provided integrally with the shaft to release the engagement with the magnifying blade when the shaft rotates in the reverse direction and to push the magnifying blade outward to expand.

According to the above configuration, after excavating an underground hole having a required depth in a state in which the enlarged blade is engaged with the kicking pin and folded, when excavating the enlarged hole, the excavating blade is cut into the bottom of the hole. When the drive shaft is rotated in the reverse direction after fixing the outer cylinder, the shaft rotates in the reverse direction within the range where the key part and the key groove fit loosely, and the kick pin is disengaged from the enlarged blade. Press to expand. Therefore, when the drive shaft is rotated forward, the expanding blade completely expands due to the resistance of the soil, and excavates the soil together with the excavating blade. After drilling a large diameter hole with a predetermined depth, pull up upward while rotating the drive shaft in the reverse direction.The enlarged blade is folded while rotating due to the resistance of the soil, and the kicking pin engages with the enlarged blade. And return to the original state.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, the enlarged hole excavating head 1 has a connection portion 2 of a drive shaft such as a screw auger at an upper end portion and an axial keyway 3 at the lower end portion which is diametrically opposed to each other. The outer cylindrical body 7 having the key portions 5 and 5 on the inner peripheral surface and the excavating blades 6 and 6 provided on the outer peripheral surface is inserted into the formed shaft 4. The enlarged blades 8, 8 are rotatably supported by the brackets 17, 17 at least at positions facing the outer cylindrical body 7 in the diametric direction, and are engaged with the enlarged blades 8, 8. During forward rotation of the shaft 4, the enlarged blades 8, 8 are held in a folded state within the maximum radius of the excavating blades 6, 6, and at the time of reverse rotation, the kicking pins 9, which push the enlarged blade 8 radially outward. 9 is provided on a plate 13 fixed to the shaft 4.

The shaft 4 has a shaft hole 10 and the connecting portion 2
The screw auger 30 has a different diameter cross section such as an oval cross section.
And a pin 12 (see FIG. 5) is inserted into the groove 11 from the lower end to prevent the lower end from coming off and connect. The keyway 3 is formed as a rectangular recess having a predetermined length and width in the outer peripheral surface of the lower end of the shaft 4. An oval-shaped plate 13 is fixed in the middle of the shaft 4 in a brim-like shape.
Are respectively protrudingly provided.

The outer cylinder 7 has a bottomed cylindrical shape,
The shaft 4 below the shaft 4 is fitted in the axial direction, and has a cylindrical portion 14 that matches the shaft hole 10 of the shaft 4, and the cylindrical portion 14 is provided with a check valve. A central bit 15 is provided across the tubular portion 14, and excavating blades 6, 6 provided with outer edge bits 16 diametrically opposed to each other around the central bit 15 are provided on the outer peripheral surface of the outer cylindrical body 7. I have.

A bracket 17 positioned between the plate 13 and the digging blade 6 is provided on the outer peripheral surface of the upper portion of the outer cylinder 7.
Are fixed to face each other in the diametrical direction.
A magnifying blade 8 is sandwiched between them, and one end thereof is rotatably supported by a pin 18. A stopper 17a is provided to connect the ends of the upper and lower brackets 17 so that the enlarged blade 8
Can be reciprocated only within a predetermined angle α about the pin 18 in FIG.

The enlarged blade 8 has a hook-shaped end at the other end to form an engaging portion 19, which can be disengaged from the kicking pin 9 of the plate 13. The enlarged blade 8 is folded by engaging the engaging portion 19 with the kicking pin 9 as shown by a solid line in FIG. 2 except when the bottom hole is excavated, and is set within the turning radius R of the excavating blade 6. during diameter hole drilling is expanded reach maximum radius R _1.

In order to transmit the torque of the shaft 4 to the outer cylinder 7, the key portion 5 is provided so as to protrude from the inner peripheral surface of the outer cylinder 7 and enter the key groove 3. . The key portion 5 projects from a plate 21 fixed to the outer peripheral surface of the outer cylinder 7 with bolts 20, protrudes from a window hole 22 of the outer cylinder 7, and enters the key groove 3.
The key portion 5 has a rectangular shape having a width smaller than the width of the key groove 3 so that the shaft 4 can slightly idle around the outer cylinder 7.

Next, the operation of the enlarged hole excavating head 1 will be described. As shown in FIG. 3, when excavating the underground hole 40 to a predetermined depth from the ground, as shown in FIG. In the state where the engaging portion 19 of the enlarged blade 8 is engaged with the kicking pin 9 and folded, it is connected to the screw auger 30 and the shaft 4 is rotated, and the excavating blade 6 scrapes the soil. Excavation while transporting

As shown in FIG. 5, when the underground hole 40 reaches a predetermined depth to form the enlarged hole 41, the screw auger 30 and the shaft 4 are temporarily stopped from rotating for excavation. By applying a pushing force in the axial direction to the screw auger 30 and pushing the shaft 4 in the ground direction, thereby pushing the outer cylinder 7 against the hole bottom 42,
As shown in FIG. 3, the center bit 15 and the outer edge bit 1
The outer cylinder 7 is fixed by making the holes 6 and 16 bite into the hole bottom 42.

With the outer cylinder 7 fixed to the hole bottom 42,
Screw auger 3 against the conventional forward rotation for excavation
0 and the shaft 4 are reversely rotated at a predetermined angle. That is, since the keyway 3 of the shaft 4 has a larger width in the rotation direction than the key portion 5, the outer cylinder 7 is fixed to the hole bottom 42 and does not rotate, and only the shaft 4 rotates slightly in the reverse direction. When the shaft 4 rotates in the reverse direction, the kicking pin 9 of the plate 13 is disengaged from the engaging portion 19 of the magnifying blade 8 as shown in FIG. 6, and the kicking pin 9 moves the magnifying blade 8 radially outward. Push open.

Then, when the screw auger 30 and the shaft 4 are rotated forward for excavation again, the enlarged blade 8 receives the resistance of the soil and rotates counterclockwise around the pin 18,
As shown in FIG. 7, both the excavating blades 6, 6 and the enlarging blades 8, 8 excavate the ground in order to completely abut against the stopper 17a.

Accordingly, the enlarged hole 41 is excavated in a conical cross section as shown in FIG. 5 as the enlarged blades 8, 8 gradually expand. Then, as shown in FIG.
8 is expanded to the maximum extent and the stoppers 17a, 17
in contact with stage a, the diameter pores having a large rotational radius R ₁ the rotation radius R of the drill blade 6 can further drilling. Therefore, if necessary, the screw auger 30 and the shaft 4 can be further rotated forward to drill an enlarged hole having a desired depth.

In order to return the expanded blades 8, 8 to the original state, the screw auger 30 and the shaft 4 are rotated in the reverse direction, so that the blades 8, 8 receive the resistance of the soil, and the pins 18, 18, 7, the engagement portion 19 engages with the kicking pin 9 and the enlarged blade 8 is rotated.
Is prevented from expanding and folded, and can return to its original state.

[0022]

According to the present invention described above, the expansion blade is engaged with the kicking pin that rotates together with the shaft and locked, thereby preventing the blade from expanding at the time of normal rotation and expanding the kicking pin at the time of reverse rotation. Comes off the blade, and
Because the expanding blade was pushed outward in the radial direction, when the blade was rotated forward, the expanding blade automatically expanded due to the resistance of the soil. Therefore, it is possible to form a hole having a desired depth.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is an explanatory diagram of an operation when excavating an underground hole.

FIG. 4 is a cross-sectional plan view of a head for drilling a large-diameter hole when excavating underground work.

FIG. 5 is an explanatory diagram of an operation when excavating an enlarged hole.

FIG. 6 is a cross-sectional plan view of a head for drilling a large-diameter hole when excavating a large-diameter hole.

FIG. 7 is a cross-sectional plan view of a head for excavating a large-diameter hole when excavating an enlarged hole.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Head for enlarged hole excavation 2 ... Connection part 3 ... Keyway 4 ... Shaft 5 ... Key part 6 ... Excavation blade 7 ... Outer cylinder body 8 ... Enlarged blade 9 ... Kick-off pin 13 ... Plate 17 ... Bracket 19 ... Engagement Part 40: Underground hole 41: Enlarged hole

Claims (1)

(57) [Claims] A key portion, which is loosely fitted into and engaged with a shaft having a drive shaft coupling portion formed at an upper end portion and an axial key groove formed at a lower end portion in a diametrically opposed manner. Insert the outer cylinder having a peripheral surface and having a drilling blade on the outer peripheral surface,
The enlarging blade is rotatably supported within the outer cylinder body at at least two positions diametrically opposite each other so as to be rotatable within a predetermined angle, and is engaged with the enlarging blade so that the enlarging blade is rotated when the shaft rotates forward. While holding the folded state within the maximum radius of the excavating blade, and disengaging the enlarged blade during the reverse rotation of the shaft to push the enlarged blade outward and expand the kicking pin with the shaft. An enlarged hole drilling head, which is provided integrally.