JP4051676B2 - Drilling head for embedding ready-made piles with expansion bit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ready-made pile embedding excavation head with an expansion bit used when a cylindrical or column-shaped ready-made pile mainly made of steel or concrete is installed in the ground.
[0002]
[Prior art]
Conventionally, as a method for embedding ready-made piles, a prefabricated pile insertion hole is formed in the ground by using a screw auger with a drilling bit fixed at the tip, and the ready-made pile is inserted into the ready-made pile insertion hole. There is a so-called pre-boring method.
[0003]
In this construction method, as shown in FIG. 3 (d), an enlarged bulb 2 having a diameter larger than the pile diameter is formed by a pile lowering process at the tip portion of the ready-made pile 1 to be embedded.
[0004]
As a method of forming the enlarged bulb 2, there is a method of using an excavation head attached with an enlargement bit. As shown in FIGS. 3 (a) to 3 (d), this is applied to an excavation head 3 using a screw auger or the like. The expansion bit 4 that stands up in the radial direction due to the resistance of the earth and sand by reversing the rotation is attached, and the excavation head 3 is rotated forward as shown in FIG. ), The excavation head 3 is reversed and the expansion bit 4 is protruded to cut the surrounding ground to form an expansion bulb diameter expansion hole 5, and a solidified material such as cement milk is formed in the expansion hole 5. As shown in FIG. 3C, the excavation head 3 is rotated forward to accommodate the enlarged bit 4, and the excavation head 3 is pulled out while injecting the solidified material to a predetermined height, so-called soil cement. Magnifying sphere by 2 to construct a. Before the expansion bulb 2 is solidified, the ready-made pile 1 is inserted as shown in FIG.
[0005]
For example, a conventional excavation head with an enlargement bit used for forming an enlarged bulb has a structure as shown in FIGS. 4 and 5 (for example, Patent Document 1). In this drilling head, a spiral blade 12 arranged in a spiral shape is fixed around a hollow central shaft 10 through which a liquid agent injection cylinder 11 is inserted at the center, and a part of the spiral blade 12 is cut away to expand the bit support portion 13. The expansion bit 15 is pivotally supported by the expansion bit support portion 13 with a longitudinally-supported pivot shaft 14. The pivot shaft 14 is vertically oriented parallel to the central axis 10, and the enlargement bit 15 rotates on a plane orthogonal to the central axis 10, and is always in the spiral direction of the spiral blade 12. The angle is inclined.
[0006]
In addition, there is also known a structure in which an enlarged bit support portion fixed at the central axis is provided at a position different from the spiral blade, and the enlarged bit is rotatably supported by this (for example, a patent) Reference 2).
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-350473
[Patent Document 2]
Japanese Patent Laid-Open No. 11-62452
[Problems to be solved by the invention]
The above-described conventional pile embedding excavation head with an expansion bit has a large resistance during excavation because the expansion bit protrudes in an arrangement perpendicular to the central axis of rotation of the head. There was a problem of hindering the discharge of water.
[0010]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a ready-made pile embedding excavation head with an enlarged bit with less sediment discharge resistance by spiral blades during excavation during forward rotation. It is.
[0011]
[Means for Solving the Problems]
In order to solve the conventional problems as described above and achieve the intended purpose, the invention according to claim 1 is characterized in that a spiral spiral wing is provided around the central axis, and a drilling bit is provided at the lower end. together with, the larger the bit that protrudes from the outer peripheral of the spiral blade is provided during the reverse rotation, the expansion bit with ready-made pile embedded drilling head is detachably fixed to the lower end of the rotary shaft, the expansion bits, spiral vanes Each enlarged bit is provided in a symmetrical arrangement on both the upper and lower surfaces of the blade , and the base end side thereof is rotatably supported on an inclined surface along the surface of the spiral blade, and the enlarged bit is provided on the surface of the spiral blade. A stopper that supports the back surface of the excavation head in a state of rising in the radial direction of the excavation head is provided.
[0012]
By configuring in this way, the expansion bit is housed at a position along the surface of the spiral blade, so that the resistance at the time of soil removal by the spiral blade is reduced, and smooth soil removal is performed. In addition, the cross-sectional area of the enlarged bit can be increased with less earthing resistance, and the ground disturbance effect by the enlarged bit is increased.
[0013]
According to a second aspect of the present invention, in addition to the configuration of the first aspect, the stopper is substantially the same height as the thickness of the enlarged bit, and the length in the head rotational radius direction is substantially the same as the width of the enlarged bit. The front side of the stopper when the head rotates forward is an inclined surface that reaches the surface of the spiral blade.
[0014]
A feature of the invention according to claim 3 is that a spiral spiral blade is provided around the central axis, an excavation bit is provided at the lower end, and an expansion bit that protrudes from the outer periphery of the spiral blade during reverse rotation is provided. In the ready-made pile embedding excavation head with an enlargement bit which is detachably fixed to the lower end of the rotation spindle, the enlargement bit is rotatable on an inclined surface along the surface thereof with respect to the spiral blade. A stopper that supports the back surface of the spiral wing surface in a state where the magnifying bit rises in the rotational radius direction of the drilling head is projected on the surface of the spiral blade, and the stopper rotates at the same height as the thickness of the magnifying bit. An inclined surface having a length in the radial direction that is substantially the same as the width of the enlarged bit and reaching the spiral blade surface on the front side of the stopper when the head rotates forward It lies in the fact was.
[0015]
By configuring in this way, when the earth is removed by the spiral blade during forward rotation, the expansion bit is positioned at the back of the inclined surface, and the earth removal resistance can be reduced.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to FIGS.
[0017]
FIG. 1 shows an outline of an excavation head according to the present invention, and reference numeral 20 in the drawing denotes a central axis of the excavation head A. The central shaft 20 has a hollow cylindrical shape through which a liquid agent injection cylinder 21 is inserted at the center as in the above-described conventional example, and a male coupling portion 23 for coupling to the rotary spindle 22 is provided at the upper end. .
[0018]
Around the central axis, two spiral blades 24 formed by spirally forming a strip-shaped steel plate are integrally fixed. The two spiral blades 24 are installed on the target with the spiral pitch shifted by 180 degrees, the lower ends protrude downward from the lower end of the central shaft 20, and the lower end edges 25 are on a straight line passing through the rotation axis. And symmetrically arranged around the rotation axis.
[0019]
The spiral inclination angle of each spiral blade 24 is set so that the spiral diameter is equal to the height corresponding to 3/4 of the spiral pitch. The spiral inclination angle as a whole may be equal to or less than the above inclination angle, or the upper end portion may be equal to or less than the above inclination angle, and may gradually be gradually inclined toward the lower end.
[0020]
Excavation bits 26, 26,... Project from the lower edges of the spiral blades 24 in the respective spiral extension directions. A liquid agent discharge port 27 is opened at the lower end of the central shaft 20, and a pair of central portion excavation bits 28 project from both sides of the discharge port 27. Each central excavation bit 28 is directed in the same direction as the excavation bit 26 at the lower end of the spiral blade 24 on the side close to each spiral blade 24.
[0021]
Enlargement bits 31 are provided on the outer peripheral edge portions of the spiral blades 24 on the lower side of the treetop from the mid-height of the excavation head A. As shown in FIG. 2, each of the enlarged bits 31 is raised in the rotational radial direction of the spiral blade 24 from the position where it is directed in the circumferential direction of the spiral blade 24 and falls inward from the peripheral edge thereof, and the tip thereof is spiral blade. It is attached so that it can rotate between positions protruding from the outer periphery of 24.
[0022]
Each of the enlarged bits 31 is used in the same orientation on both the upper and lower sides in an arrangement that sandwiches each of the spiral blades 24, and each base end portion 32 is formed in a substantially semicircular shape, and the circular center portion of the semicircular shape A pivot hole 33 is opened at the center.
[0023]
Enlarged bit support fittings 34 are fixed to the enlarged bit attachment positions of the spiral blades 24, respectively. The metal fitting 34 is fixed so as to fill a space in which a part of the spiral blade 24 is cut out, and a flat plate portion 34 a whose upper and lower surfaces are substantially flush with the upper and lower surfaces of the spiral blade 24, and the flat plate portion 34. The flat plate portion 34a is fixed at an inclination angle substantially the same as the spiral inclination angle of the spiral blade 24.
[0024]
This stopper portion 34b is used when the excavation head A is rotated forward, that is, when the excavation head A is rotated so that the excavated sediment is conveyed upward by the spiral blade 24 (in this specification, the rotation is the normal rotation in this direction). , The rotation in the opposite direction is the reverse rotation), and has a dimension substantially the same as the width a of the enlarged bit 31 and the protruding height is substantially the same as the thickness b of the enlarged bit 31. The same dimensions are formed. The front side in the forward rotation direction of the stopper portion 34 b is a gently inclined surface 34 c that reaches the upper surface or the lower surface of the spiral blade 24.
[0025]
The stopper portion 34b is configured so that when the enlarged bit 31 rises in the direction of the turning radius of the excavating head A on the rising surface on the flat plate portion 34a side, the back surface thereof comes into contact with the rising surface to maintain the rising state. When the excavation head A is rotated forward, the expansion bit 31 is tilted to the circumferential side of the spiral blade by the resistance of the surrounding ground. When the excavation head A is rotated in the reverse direction, the rotation radius is increased by the resistance of the surrounding earth and sand. The rear surface is brought into contact with the stopper portion 34b to prevent the rotation and maintain the rising state.
[0026]
The excavation head A configured as described above is used in place of the excavation head used in the above-described conventional pre-boring method, and the ground is excavated by the excavation bits 26 and 28 by rotating the excavation head in a normal direction. The pile insertion hole is formed while being earthed by 24. At the time of excavation, as shown by the solid line in FIG. 2, the enlarged bit 31 is tilted to the moving rear side of the stopper portion 34 b and is housed in a position along the upper and lower surfaces of the spiral blade 24. And after excavating to a predetermined depth, in order to form the expansion bulb | ball in the conventional construction method mentioned above, it pulls up reversely rotating. As a result, the enlarged bit 31 rises as indicated by the provisional line in FIG. 2 and protrudes from the outer periphery of the spiral blade 24 to disturb the periphery of the leading hole. At the same time, a bulb is formed by injecting a solidifying agent such as cement milk.
[0027]
【The invention's effect】
As described above, the prefabricated pile embedding excavation head with an expansion bit according to the present invention is housed in a position along the surface of the spiral blade during the excavation by forward rotation. Sediment discharge resistance is reduced, and pile insertion hole formation while unloading can be performed smoothly with less energy.
[Brief description of the drawings]
FIG. 1 is a side view showing an example of an excavation head according to the present invention.
FIG. 2 is a bottom view of the excavation head shown in FIG.
FIG. 3 is a cross-sectional view schematically showing the steps of a conventional preboring method.
FIG. 4 is a side view showing a conventional drilling head with an enlarged bit.
FIG. 5 is a cross-sectional view taken along line AA in FIG.
[Explanation of symbols]
A Drilling head 20 Center shaft 21 Liquid agent injection path 22 Rotating support shaft 23 Male connecting portion 24 Spiral blade 25 Lower end edge 26 Drilling bit 27 Liquid agent discharge port 28 Center portion drilling bit 31 Expansion bit 32 Base end portion 33 Pivoting hole 34 Expanded wing support bracket 34a Flat plate portion 34b Stopper portion 34c Inclined surface

Claims (3)

A spiral spiral wing is provided around the central axis, an excavation bit is provided at the lower end, and an enlarged bit protruding from the outer periphery of the spiral wing at the time of reverse rotation is provided. In the ready-made pile embedding excavation head with expansion bit to be
The enlarged bit is provided in a symmetrical arrangement on both upper and lower surfaces of the spiral wing, and each enlarged bit is supported so that the base end side is rotatable on an inclined surface along the surface of the spiral wing,
A prefabricated excavation head for embedding piles with an enlarged bit, characterized in that a stopper is provided on the surface of the spiral blade to support the back of the enlarged bit in a state where the enlarged bit rises in the radial direction of the excavating head. The stopper is substantially the same height as the thickness of the enlarged bit, and the length in the head rotational radius direction is substantially the same as the width of the enlarged bit. The ready-made pile embedding excavation head with an expansion bit according to claim 1, wherein the excavation head is an inclined surface reaching the surface. A spiral spiral wing is provided around the central axis, an excavation bit is provided at the lower end, and an enlarged bit protruding from the outer periphery of the spiral wing at the time of reverse rotation is provided. In the ready-made pile embedding excavation head with expansion bit to be
The expansion bit is supported so that the base end side is rotatable on an inclined surface along the surface of the spiral wing,
On the surface of the spiral wing, a stopper that supports the back surface of the expansion bit in a state where the expansion bit rises in the direction of the excavation head rotation radius is projected,
The stopper has a height substantially the same as the thickness of the enlarged bit and a length in the head rotating radial direction that is substantially the same as the width of the enlarged bit. A drilling head for embedding pre-made piles with an enlarged bit that forms an inclined surface that reaches the wing surface.

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