JP6427477B2 - Expanded hole drilling head - Google Patents

Description

  The present invention relates to an enlarged hole drilling head, and more particularly to an enlarged hole drilling head used when constructing a foundation steel pipe pile or a concrete pile having a bulb portion in civil engineering work.

  In order to construct a foundation steel pipe pile or a concrete pile, the underground hole is excavated with an earth drill, a screw auger or the like, and a foundation steel pipe pile or a concrete pile is constructed. At this time, in order to increase the supporting force of the foundation steel pipe pile or the like, the bottom of the underground hole is excavated at a required depth position to widen the lower end of the underground hole in a bulbous shape.

Thus, as means for forming a bulb-like widening portion at the lower end portion of the underground hole, for example, a digging head provided with an expanding digging blade as disclosed in JP-A-11-350473, and the like expanding large drilling apparatus disclosed in 1-75194 JP.

  According to the invention disclosed in the above-mentioned JP-A-11-350473, when the tip of the steel pipe pile reaches the support layer, the auger screw inserted into the inside of the steel pipe pile is reversed to be contracted at the lower end of the auger screw This is a method of expanding the portion where the tip of the steel pipe pile is located by expanding and simultaneously moving the expanding bit inserted in the diameter state.

  Further, in the magnifying and excavating apparatus disclosed in Japanese Utility Model Application Laid-Open No. 1-75194, the excavating blade is inserted into the ground to restrain the rotation and then the excavating rod is reversed to move the tip of the pressure knock toward the rear end of the expanding blade. The expansion blade is forced to rotate outward by pushing out and pushing this out, and it is made to carry out expansion excavation by the spread expansion blade.

  In these drilling heads and expansion drilling devices, in order to drill an enlarged hole, the operation must be changed from positive rotation (clockwise direction) to reverse rotation (counterclockwise direction). In that case, since the tip of the auger head and the cutting blade rotate in the opposite direction, the ability to dig the bottom of the underground hole is significantly reduced, and the working efficiency is also significantly reduced. In addition, in the case of the expansion drilling apparatus, there is no means for locking the expansion blade at the time of forward rotation of the drilling rod, so rock etc. enter between the expansion blade and the press knock at the time of forward rotation to rotate the expansion blade, There is also the possibility that the expanded hole will be dug carelessly.

  Therefore, as in the inventions described in Japanese Patent No. 2711236 and Japanese Patent No. 4945603, the inventors can perform positive rotation even when digging the expanded hole, and can form the expanded hole to a desired depth, An expanded hole drilling head has been proposed which prevents the expanded blade from being expanded inadvertently during forward rotation. That is, in the case of the enlarged hole excavating head disclosed in Japanese Patent No. 2711236, when the enlarged hole is excavated, the excavating blade bites into the hole bottom to fix the outer cylindrical body, and then the drive shaft is reversely rotated. In the range in which the key portion and the key groove are loosely fitted, the kicking pin is released from the expanding blade by reverse rotation, and the expanding blade is expanded by pushing it radially outward.

  Then, when the drive shaft is rotated forward, the expansion blade receives the resistance of the soil and is completely expanded, and excavates the soil with the digging blade. Then, after drilling a wellbore having a predetermined depth, if the drive shaft is pulled up while being reversely rotated, the expanding blade is folded while rotating due to the resistance of the soil, and the kicking pin engages with the expanding blade Return to the original state.

  In the case of the enlarged hole excavating head disclosed in Japanese Patent No. 4945603, when the enlarged hole is excavated, the diameter reduction holding of the expanded vane held in the folded state within the radius of the digging blade by the enlarged wing operating member By releasing the expansion blade and pushing the expansion blade outward almost simultaneously, the expansion and contraction of the expansion blade can be reliably performed. At the same time, when the upper shaft is reversely rotated, the expansion blade is operated. The kicker of the member forcibly pushes the expanding wing outward to a position where the tip of the expanding wing projects from the radius of the digging blade, thereby making the radius of the digging blade even in the case of a viscous ground. The diameter can be reliably expanded to the outside.

  Furthermore, when the expansion wing is pushed and expanded to a predetermined angle, the inner surface in the vicinity of the shaft portion of the expansion wing abuts against the stopper, so the expansion wing is pushed and expanded to a predetermined angle and the diameter expanded state is maintained. It is assumed that the expanded hole of the can be duly drilled.

Japanese Patent Application Laid-Open No. 11-350473 Japanese Utility Model Publication No. 1-75194 Patent No. 2711236 gazette Patent No. 4945603

  However, in the above invention, the construction is made to cope with the viscous land, so the structure of the expanded hole drilling head becomes complicated, but in the construction of a large diameter pile with a large diameter, the durability decreases and it is frequently There were limitations in use such as the need to repair the drilling head. In addition, in the case of a high quality N soil soil having a large drilling resistance (N value), problems such as difficulty in drilling itself have occurred.

  In order to overcome the drawbacks of the prior art as described above, the present invention improves the durability as well, since the operation of diameter expansion and diameter reduction of the expansion wing can be realized with a simple structure, It is an object of the present invention to provide an enlarged hole excavating head capable of reliably forming an enlarged hole even in a ground having a large excavation resistance.

In order to achieve the above object, according to a first aspect of the present invention, a lower shaft is connected to a lower end portion of an upper shaft provided with a connecting portion connected with a drive shaft at an upper end portion so as to be rotatable forward and reverse by a predetermined angle. Then, the lower shaft is an enlarged wing support member composed of an upper bracket and a lower bracket pivotally supporting the expansion wings at a predetermined angle at at least two diametrically opposed positions, One end of the upper shaft abuts on the rear end surface of the arm portion of the expanding blade during normal rotation, and the expanding blade is held in a folded state within the radius of the digging blade attached to the lower shaft as the torque transmission unit, also during the reverse rotation, the other end to the distal end portion and the strike of the expansion blades, forcing the expansion wings to a position where the tip of the expanded wings protrudes from the radius of the excavating blade Outward direction An enlarged hole drilling head equipped with expansion blades operating members respectively function as a kick-out portion for diameter expansion, the expansion wings inner surface of the arm portion of the expansion blades during forward rotation of the upper shaft abuts As a stopper that prevents the diameter of the expansion shaft from expanding, and when the upper shaft rotates in reverse, the inner surface of the arm portion of the expansion blade abuts and is sheared , and a detection unit that detects the expansion diameter of the expansion blade the expansion wings detection means which function respectively, provided between the upper bracket and the lower bracket of the expansion wing support member, the expansion wings are expanded and contracted in contact with the larger blade outer surface of the arm portion of the person The enlarged blade support member is provided with a stopper member for restricting the movement .

The invention of claim 2 of the present application, the expanded wings detecting means, a said upper bracket and a bolt which upper and lower end portions were respectively fixed to the lower bracket of the expansion wing support member, for the expansion wings at a yet larger than the thickness of intervals of the shaft portion near to comprising the shear guide grooves in upper and lower two places.

The present invention as described in claim 3 of the present application, the excavating blade mounted on the lower shaft, characterized in that a substantially and the auxiliary expansion vanes whose diameter increases until Kuigai diameter positioning member.

In the present invention, the upper bracket and the lower bracket of the expansion wing support member are used as a stopper for preventing the expansion wing from expanding due to the inner surface of the arm portion of the expansion wing coming into contact when the upper shaft rotates forward. When the upper shaft is reversely rotated, the inner surface of the arm portion of the expansion blade collides and is sheared, and an expansion wing operation member comprising detection means functioning as a detection unit for detecting the expansion diameter of the expansion wing is provided. With this structure, the structure can be simplified, and as a result, the thickness of the component members can be increased to enhance the durability.

In addition, the expansion wing supporting member has a structure in which the expansion wing supporting member is provided with a stopper member that abuts on the outer surface of the arm portion of the expansion wing to limit the expansion movement of the expansion wing, thereby keeping the rotation radius of the expansion wing constant. It is possible to reliably drill a drill hole of the desired diameter size at the bottom of the underground hole.

  In addition, the stopper member provided on the expansion wing support member is in contact with the outer surface of the arm portion of the expansion wing to restrict the diameter reduction of the expansion wing, so that the expansion wing does not enter the lower shaft side too much be able to.

  Further, in the present invention, by observing the expanded blade detection means, it is possible to confirm that the expanded blade is expanded in diameter surely and the expanded hole having a predetermined diameter is drilled in the expanded state.

In the present invention, the expansion wings detecting means, a bolt which is fixed to the upper bracket and the lower bracket upper and lower end portions of the expanding blade support member, not greater than the shank thickness of the vicinity of the larger wing spacing By providing the shear guiding grooves at two places in the upper and lower sides, when the bolt is subjected to pressure, it is surely sheared at the position of the shear guiding groove and the diameter expansion of the expansion wing is inhibited. Therefore, when it is desired to expand the diameter of the expansion blade, the diameter can be reliably expanded.

Further, according to the present invention, the excavating blade mounted on the lower shaft, substantially an auxiliary expansion vanes whose diameter increases to Kuigai diameter from the provision of the positioning member, a high drilling resistance of large N value gravelly soil But drilling of the expanded hole becomes easy.

It is a front view of the head for the extended hole excavation concerning the present invention. It is a right view of the head for the same expansion hole excavation. It is a front view in the state where the auxiliary expansion wing of the head for the same expansion hole excavation was diameter-expanded. It is the CC sectional view taken on the line of FIG. It is the BB sectional drawing of FIG. It is CC sectional view taken on the line of FIG. 1 at the time of the diameter expansion operation start of an expansion wing | blade. It is the BB sectional drawing of FIG. 1 at the time of the diameter expansion operation start of the same expansion wing | blade. It is CC sectional view taken on the line of FIG. 1 at the time of diameter expansion operation 1st step of the expansion blade. It is the BB sectional drawing of FIG. 1 at the time of diameter expansion operation 1st step of the expansion blade. It is CC sectional view taken on the line of FIG. 1 at the time of expansion operation 2nd step of the expansion blade. FIG. 7 is a cross-sectional view taken along the line C-C in a state where the diameter of the expansion blade is expanded to the maximum. It is a bottom view in the state where diameter of an auxiliary expansion wing was expanded to the maximum. It is an enlarged view of D part of FIG. It is the enlarged view after shear pin shear of D part of FIG. It is longitudinal cross-section explanatory drawing at the time of an expanded hole excavation.

It will be described in detail below by examples showing the present invention in FIG. 1 to FIG. In the figure, reference numeral 1 is a head for drilling an enlarged hole according to the present invention, and 2 is an upper shaft having a connecting portion 3 with a drive shaft 101 at an upper end portion. Reference numerals 4 and 4 denote key grooves formed on the inner peripheral surface of the shaft hole 5 of the upper shaft 2, and the key grooves 4 and 4 extending in the axial direction A are opposed to each other in the diameter direction of the upper shaft 2. Are respectively formed. In the figure, reference numeral 6 denotes a spiral digging blade provided on the lower outer peripheral surface of the upper shaft 2.

Reference numeral 8 denotes a lower shaft, and on the outer peripheral surface of the upper end portion of the lower portion of the lower shaft 8 , key portions 9, 9 loosely engaged with key grooves 4 in the shaft hole 5 of the upper shaft 2 are engaged. A spiral digging blade 10 is provided on the outer peripheral surface, and the upper end portion of the lower shaft 8 is inserted into the lower shaft hole 5 of the upper shaft 2 to connect the both shafts 2 and 8 There is.

  The upper shaft 2 and the lower shaft 8 have a central angle 60 with respect to the lower shaft 8 in the range where the key groove 4 and the key portion 9 are loosely fitted, for example, in the present embodiment. It can be rotated forward (clockwise) and reverse (counterclockwise) within a range of degrees. In the figure, reference numeral 11 denotes a plurality of cutting edges provided in a line at the lower end portion of the cutting blade 10.

An enlarged wing support member 12 fixed to the upper portion of the lower shaft 8 is composed of an upper bracket 12a and a lower bracket 12b which are horizontally separated from each other in plan view mounted separately from each other in the vertical direction. Insertion holes 14 for attaching bolts 13a, which will be described later, are formed near two side surfaces 12c at both ends of 12a and 12b and opposite to each other in the diameter direction of the lower shaft 8.

  An enlarged wing 15 is composed of an arm 18 formed to have a large width and / or thickness to improve durability and a tip blade 19 provided at the tip thereof, and on the side of the inner side surface 18a of the arm 18 It is installed in the vicinity of both ends between the upper and lower brackets 12a and 12b in the vicinity of the bent rear end so as to be pivotable by cylindrical shaft portions 16 and 16.

  An enlarged wing control member 20 mounted on the upper shaft 2 via a plate 21 is a horizontal base in a front view in which each of the outer shaft 21a of the plate 21 is suspended from the diametrically opposite position of the upper shaft 2 The one side end 20a is directed to the rear end face 18b side of the arm portion 18 of one expansion wing 15 and the other side end 20b is directed to the tip blade 19 side of the other expansion wing It is fixed to the plate 21 and installed so as to be rotatable in the circumferential direction about the upper shaft 2.

With the above configuration, the shaft of the enlarged wing 15 is rotated by positively rotating the upper shaft 2 and bringing one end 20 a of the enlarged wing operating member 20 into contact with the rear end face 18 b of the arm portion 18 of one enlarged wing 15. The diameter-expanding movement centering on the part 16 can be prevented. Further, the upper shaft 2 is reversely rotated, and the other side end 20b of the expansion wing operation member 20 is abutted against the inner side 19a of the tip end blade 19 of the other expansion wing 15, whereby the expansion wing around the shaft portion 16 is enlarged. 15 can be forcibly expanded.

The outer peripheral surface 13 has a function as a stopper for preventing the expansion blade 15 from being inadvertently expanded and a shear pin as expansion blade detection means for detecting the expansion blade 15 when the diameter is expanded. The bolt 13a has two shear guiding grooves 13c and 13c spaced apart vertically at a distance slightly larger than the thickness in the vicinity of the shaft portion of the expansion blade 15. In the figure, reference numeral 13b denotes a nut screwed to the bolt 13a from the lower surface side of the lower bracket 12a, and the shear pin 13 is fixed so as to extend between the upper and lower brackets 12a and 12b.

A stopper 22 is mounted on the side surface 12c near both ends of the upper and lower brackets 12a and 12b, and is disposed near the outer surface 18c of the arm 18 near the shaft of the enlarged wing 15. The stopper member 22, the the are two arranged in opposite position at a diameter direction of the lower shaft 8ゝmonitor, upper and lower two brackets 12a, it is fixed to HashiWataru Suyo during 12b.

With the above configuration, when the enlarged wing 15 is first folded within the radius R of the digging blades 6 and 10, the outer surface 18c of the arm 18 near the shaft of the enlarged wing 15 is the stopper member 22. The expanding wing 15 restricts the movement of the diameter of the expanding wing 15 toward the lower shaft 8 more than necessary around the shaft portion 16 so that the expanding wing 15 does not enter the lower shaft 8 too much. It is supposed to be.

Also, if the expansion blades 15 are expanded outwardly around the shaft portion 16, which receives the pressure stronger the shear pin 13 by the inner side surface 18a of the arm portion 18 of the expansion blades 15, the shear pins 13 are the upper and lower It is possible to detect that the diameter of the expanding blade 15 is increased by shearing between the two shear guide grooves 13c and 13c. After the shear pin 13 is sheared, the rear end portion of the arm portion 18 of the expansion wing 15 can freely pass between the shear pins 13 and 13 left on the upper and lower brackets 12a and 12b .

When the rear end portion of the arm portion 18 passes between the shear pins 13 and 13 left on the upper and lower brackets 12a and 12b and the expanding wing 15 is maximally expanded in diameter about the shaft portion 16, that is, The outer surface 18c of the arm portion 18 in the vicinity of the shaft portion of the enlarged wings 15, 15 when the diameter of the lower shaft 8 respectively expands to a position where the two enlarged wings 15, 15 opposed to each other in the diametrical direction become straight. Is abutted with the tip end surface 22b of the stopper member 22, the expansion movement of the expansion wing 15 is stopped, and the diameter expansion of the expansion wing 15 around the shaft portion 16 is prevented.

  Reference numeral 23 denotes an auxiliary expansion wing provided near the outer periphery of the excavating blade 10 of the lower shaft 8 so as to sandwich the excavating blade 10 inside an L-shaped bracket 24 which is a positioning member. It is rotatably supported by a nut 25b. The auxiliary enlarged wing 23 is centered on the bolt 25 a from the state where it is folded within the radius R of the digging blade 10 until the side portion 23 a of the auxiliary enlarged wing 23 abuts on the upper side 24 a of the bracket 24. The diameter can be expanded, and the enlarged diameter can be excavated at the lower part of the underground hole 111 by the two enlarged auxiliary diameters 23 and 23.

In addition, in a normal state, the auxiliary enlarged wing 23 is fixed to the digging blade 10 by point welding in a folded state so that the diameter of the auxiliary enlarged wing 23 is not inadvertently increased. The auxiliary expansion blades 23 are rotated radius r1 in the case of diameter up, the so enlarged wing 15 is slightly smaller than the rotation radius r2 in the case of diameter up to the length of the auxiliary expansion blades 23 Is set.

  Next, the operation of the enlarged hole excavating head 1 will be described. When excavating the underground hole 111 of a predetermined depth from the ground, the drive shaft 101 is rotated forward (rotated clockwise) to drive the drive shaft. The upper shaft 2 connected to the connector 101 via the connector 3 and the enlarged wing operating member 20 mounted on the upper shaft 2 via the plate 21 rotate in the same direction.

As shown in FIG. 4 and FIG. 5, when the expansion wing operation member 20 rotates forward, one end 20 a of the hanging portion of the expansion wing operation member 20 abuts on the rear end face 18 b of the arm portion 18 of the expansion wing 15. . As a result, the expansion movement around the shaft portion 16 of the expansion wing 15 is blocked, and the expansion wing 15 is maintained in the folded state within the radius R of the digging blades 6 and 10.

At the same time, the outer surface 18c of the arm 18 near the shaft of the expansion wing 15 abuts on the slope 22a of the stopper member 22 to further move the expansion wing 15 toward the lower shaft 8 about the shaft 16 (contraction Drooping movement is also blocked. As a result, the magnifying wing 15 can not rotate about the shaft portion 16 and the folded state is fixed within the radius R of the digging blades 6 and 10.

Here, due to some problem, the upper shaft 2 is reversely rotated, and as shown in FIGS. 6 and 7, one end 20a of the enlarged wing operating member 20 is slightly separated from the rear end face 18b of the arm portion 18 of the enlarged wing 15. even when an inner side surface 18a of the arm portion 18 of the expansion blades 15 abuts the shear pin 13, movement of the enlarged diameter shaft portion 16 around the expansion blades 15 is prevented, for expanding wings 15 drilled The folded state is maintained within the radius R of the blade 10.

  The enlarged wing operating member 20 mounted on the upper shaft 2 and the upper shaft 2 via the plate 21 rotates forward, and as shown in FIG. 5, the positive rotation direction side of the key groove 4 of the shaft hole 5 of the upper shaft 2 The end face 4 a of the lower shaft 8 abuts on the key portion 9 of the lower shaft 8. Then, when the upper shaft 2 further rotates forward, the lower shaft 8 rotates forward together with the upper shaft 2.

Thereby, since the excavating blade 6, 10 and the drilling edge 11 is mounted on the outer peripheral surface of the upper shaft 2 and a lower shaft 8 rotates in the same direction, relative to the lower shaft 8 via the upper shaft 2 by a drive shaft 101 By applying a pressing force in the axial direction A, the underground hole 111 of a predetermined depth can be excavated on the ground 113.

  Next, after the underground hole 111 reaches a predetermined depth from the ground, when forming the expanded hole 112 in the lower part of the underground hole 111, once the rotation of the drive shaft 101 is stopped, the drive shaft 101 is also driven. The cutting edge 11 provided at the lower end of the digging blade 10 of the lower shaft 8 is made to bite into the hole bottom 114 by applying pressing force in the axial direction A to the lower shaft 8 via the upper shaft 2 by the The lower shaft 8 is fixed to the hole bottom 114.

  Then, in a state where the lower shaft 8 is fixed to the hole bottom 114, the drive shaft 101 is reversely rotated (counterclockwise rotation), and the upper shaft 2 connected to the drive shaft 101 is reversely rotated. That is, within the range in which the key groove 4 of the upper shaft 2 and the key portion 9 of the lower shaft 8 are loosely fitted from the state shown in FIG. 4 and FIG. By rotating the upper shaft 2 in the reverse direction, the end surface 4b on the reverse rotation direction side of the key groove 4 of the upper shaft 2 strikes the key portion 9 of the lower shaft 8 in the state shown in FIG.

  When the upper shaft 2 is reversely rotated, one end 20 a of the hanging portion of the expansion wing operating member 20 attached to the upper shaft 2 via the plate 21 is the rear end face 18 b of the arm 18 of one expansion wing 15. And abut from the state shown in FIG. Then, by continuing the reverse rotation of the upper shaft 2, the expansion wing operation member 20 approaches the other expansion wing 15 while drawing a circular arc, and as shown in FIG. The side end 20 b abuts on the inside portion 19 a of the tip blade 19 of the enlarged wing 15.

  Then, when the upper shaft 2 is reversely rotated even after the state shown in FIG. 9 in which the end face 4b on the reverse rotation direction side of the key groove 4 of the upper shaft 2 collides with the key portion 9 of the lower shaft 8, the enlarged wing operation member The other end 20b of the hanging portion 20 moves to the position of the inner side 19a of the tip blade 19 of the expansion blade 15 (see FIG. 8). Accordingly, the end blade 19 of the expansion wing 15 is forcibly pushed out by the expansion wing operation member 20 and rotates counterclockwise around the shaft portion 16 so that the outer portion 19 b of the end blade 19 is the digging blade 6, 10 Move to a position where it protrudes outside the radius R of the (diameter expansion).

As described above, the enlarged wing 15 is expanded in the counterclockwise direction (outward direction) around the shaft portion 16 by the enlarged wing operation member 20, whereby the rear end portions of the arm portions 18 of the two enlarged wings 15, 15 Also, it rotates counterclockwise around the shaft portion 16. As a result, as shown in FIG. 13, the shear pin 13 fixed so as to bridge between the upper and lower brackets 12a and 12b is subjected to pressure by the inner side surface 18a of the arm portion 18, and as shown in FIG. Shearing is performed at the position of the shear guiding grooves 13c, 13c. Then, the rear end portion of the arm portion 18 of the expansion wing 15 can freely pass between the shear guiding grooves 13c, 13c of the shear pin 13 left in the upper and lower brackets 12a, 12b so that the expansion wing 15 can expand in diameter. Become.

Next, the drive shaft 101 is rotated forward from the state shown in FIG. Along with this, also the upper shaft 2 is connected to the drive shaft 101 rotates in the same direction, as shown in FIG. 5, the end surface 4a of the forward rotation direction of the key groove 4 comes into contact with the key portion 9 of the lower shaft 8 . Then, when the drive shaft 101 is further positively rotated, the lower shaft 8 is rotated in the same direction as the drive shaft 101 via the upper shaft 2 connected to the drive shaft 101.

The forward rotation of the lower shaft 8 causes the tip blade 19 of the expansion blade 15 moving to a position projecting outward of the radius R of the digging blade 6, 10 to the resistance of the excavated soil, and the expansion blade 15 has an axis The diameter is gradually enlarged centering on the portion 16 (see FIGS. 8 and 10). Then, the rear end portion of the arm portion 18 of the expansion wing 15 passes between the shear guiding grooves 13c, 13c of the shear pin 13 left in the upper and lower brackets 12a, 12b as described above, as shown in FIG. expansion wings 15, 15 two of you opposed in radial direction of the lower shaft 8 is expanded to the arm portions 18, 18 thereof in alignment.

At this time, the outer surface 18 c of the arm 18 near the shaft of the expansion wing 15 abuts on the end surface 22 b of the stopper member 22, so that the further expansion movement of the expansion wing 15 is blocked. Therefore, by continuing the normal rotation of the drive shaft 101 and digging, as shown in FIG. 15, the enlarged hole 112 is excavated by the tip blade 19 of the enlarged wing 15 at the lower part of the underground hole 111 of the desired depth. Can.

When the operation of excavating the enlarged hole 112 below the underground hole 111 of the desired depth is completed, the drive shaft 101 is reversely rotated. Along with that, the upper shaft 2 connected to the drive shaft 101 also rotates in the same direction, so as shown in FIG. 9 , the end face 4 b on the reverse rotation direction side of the key groove 4 of the upper shaft 2 is the key portion of the lower shaft 8 The lower shaft 8 is in reverse rotation in the same direction as the upper shaft 2.

The tip end blade 19 of the expansion blade 15 whose diameter is expanded to a position protruding outward of the radius R of the digging blades 6 and 10 by the reverse rotation of the lower shaft 8 is the outer surface 18 c of the arm portion 18. Due to the resistance of the excavated soil, the expanding wing 15 gradually reduces its diameter around the shaft portion 16 and rotationally moves to the inside of the radius R of the digging blades 6 and 10.

As described above, at the time when the tip end blade 19 of the expansion blade 15 rotationally moves to the inside of the radius R of the digging blades 6 and 10, the drive shaft 101 is rotated forward. Accordingly, the upper shaft 2 connected to the drive shaft 101 is also rotated in the same direction, and one end 20 a of the hanging portion of the expansion wing operation member 20 abuts on the rear end surface 18 b of the arm 18 of the expansion wing 15. As a result, the expansion movement around the shaft portion 16 of the expansion wing 15 is blocked, and the expansion wing 15 is maintained in the folded state within the radius R of the digging blades 6 and 10.

Here, as shown in FIGS. 13 and 14, the shear pin 13 for detecting that the enlarged wing 15 has expanded is fixed to both the upper and lower brackets 12a and 12b, so that digging of the enlarged hole 112 is performed. after the work is completed, pulling the enlarged hole drilling head 1 upwards, by observing the state of the shear pin 13 can be enlarged wing 15 detects whether or not expanded.

  Therefore, if the shear pin 13 is sheared at the position of the shear guiding groove 13c even if the enlarged wing 15 is in a folded state when the expanded hole excavating head 1 is pulled upward, At the time of excavation, it can be detected that the expansion wing 15 has actually expanded in diameter, and it can be grasped that the expansion hole 112 can be excavated at the lower part of the underground hole 111.

Further, when it is determined that the ground is hard due to the test digging and it is difficult to dig the enlarged hole 112 only by the enlarged wing 15, the fixing of the auxiliary enlarged wing 23 by the point welding is released. As a result, when the lower shaft 8 rotates forward with the drive shaft 101, the tip portion of the auxiliary enlarged wing 23 is obtained from the state shown in FIG. 2 in which the auxiliary enlarged wing 23 is folded within the radius R of the digging blade 6, 10. The diameter 23 b gradually expands around the bolt 25 a due to the resistance of the excavated soil.

Then, since the diameter of the auxiliary expansion wing 23 is expanded to the state shown in FIGS. 3 and 12 in which the side surface portion 23a of the auxiliary expansion wing 23 abuts on the upper side portion 24a of the bracket 24, the expanded hole 112 can be excavated. .

In addition, when the drilling operation of the enlarged hole 112 is finished and the enlarged hole excavating head 1 is pulled upward, the lower shaft 8 is reversely rotated with the drive shaft 101 as described above, so the auxiliary enlarged wing 23 is made of excavated soil Under the resistance, the diameter is gradually reduced, and as shown in FIG. 2, the state returns to the state of being folded within the radius R of the digging blade 6, 10.

Here, if the auxiliary expansion wing 23 is not folded by biting earth and sand while pulling up the expansion hole excavating head 1, the thickness of the digging blade 10 at the position where the auxiliary expansion wing 23 is fixed is As described above, since it is a thin structure that is weak against resistance in the vertical direction compared to other positions, the auxiliary enlarged wing 23 of the digging blade 10 is fixed by forcibly pulling up the enlarged hole drilling head 1 upward. It pulls up while destroying a thin position.

  In addition, a bolt 25a that is weak in tensile resistance may be used as the bolt 25a that rotatably supports the auxiliary expansion wing 23 on the digging blade 10. By doing this, when the earth and sand bite and the auxiliary expansion wing 23 does not fold, the head 1 for expanding hole drilling is forcibly pulled upward and the bolt 25 a is broken, and the auxiliary expansion wing 23 from the cutting blade 10 The extended hole drilling head 1 can be pulled up while dropping off.

DESCRIPTION OF SYMBOLS 1 Expansion hole excavating head 2 upper shaft 3 connection part 4 key groove 5 axial hole 6 drilling blade 7 axial part vicinity 8 lower shaft 9 key part 10 drilling blade 11 cutting edge 12 expanding blade support member 12a upper bracket 12b lower part Bracket 12c Side 13 Shear pin 13a Bolt 13c Shear guiding groove 14 Insertion hole 15 Enlarged wing 16 Shaft 18 Arm part 18a Inner side 18b Rear end face 19 Tip blade 19a Inner side 20 Expansion wing control member 20a One side end 20b Other side end 21 Plate 22 Stopper member 22a Slope 22b Tip face 23 Auxiliary expansion wing 24 Bracket

Claims (3)

When the lower shaft is connected to the lower end of the upper shaft provided with the connecting part connected with the drive shaft at the upper end so as to be able to rotate forward and reverse by a predetermined angle, the lower shaft is diametrically opposed And the upper shaft includes an upper bracket and a lower bracket for pivotally supporting the expansion wing within a predetermined angle, and the upper shaft has one end thereof when the positive rotation is performed. As a torque transmission part in contact with the rear end face of the arm part to hold the widening blade in a folded state within the radius of the digging blade attached to the lower shaft, and at the other time the other end is the widening blade expansion of in tip and impinge, respectively function as the forced out kick diameter increases outward portion of the enlarged blade to a position where the tip projects from the radius of the drilling blade of the expansion wings An enlarged hole drilling head equipped with a control member, as a stopper for the inner surface of the arm portion of the expansion blades during forward rotation of the upper shaft to prevent the expansion wing abuts it is enlarged, also When the upper shaft is reversely rotated, the inner surface of the arm portion of the expanding blade abuts and is sheared, and the expanding blade detecting means functioning as a detecting unit for detecting the diameter expansion of the expanding blade is the expanding blade the upper bracket and provided between the lower bracket, the arm portion of the outer surface and in contact with the enlarged wing support member a stopper member for limiting movement of the expansion blades are expanded and contracted in the expansion wing of the support member An expanded hole drilling head characterized by being provided in . The larger blade detecting means, a said upper bracket and a bolt which upper and lower ends are fixed respectively to the lower bracket of the expansion wing support member, at a not greater than the thickness of intervals of the shaft portion near the enlarged wing, The enlarged hole drilling head according to claim 1, characterized in that shear guiding grooves are provided at upper and lower two places. Wherein the excavating blade mounted on the lower shaft, enlarged pores drilling head according to claim 1 or 2, characterized in that a positioning member and the auxiliary expansion vanes whose diameter increases to approximately Kuigai diameter.

Images