Casing for forming pile driving hole

Abstract

To provide a casing device having good crushing efficiency and good recovery efficiency of crushed pieces.SOLUTION: In a cylindrical casing 10 in which a plate blade-like crushing claw side 11C is continuously provided along a circumferential shape of a casing end, three screw blades 2 which spirally advance are integrally fixed to a cylinder inner surface near the casing end. A short shaft column 3 having a height equal to or less than the cylinder height of the cylindrical casing is integrally held and fixed in the axial center direction of the cylinder shaft concentrically with the casing in the three circumferential screw blades 2, and a plurality of bits 12B each formed of a rotary body having a pointed shape are continuously provided along the blade side of the screw blades spirally advancing toward the center of the shaft along the end direction of the casing so that the blade tips protrude from the blade side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a casing for forming pile holes, and more particularly to a rock drilling casing for forming pile holes while excavating rock underground. [Background technology]

[0002] A bucket-type excavator used in the construction of cast-in-place concrete piles and the like has been disclosed that has a discharge port on the top surface connected to a rotating rod 3 and a bottom plate equipped with a digging blade on the bottom surface (see Patent Document 1). This boring bucket-type excavator rotates integrally with the rotating rod, and digs using the digging blade at the bottom end.

[0003] The bottom of the drilling bucket of the bucket-type excavator has a semicircular intake opening, which is opened and closed by opening and closing the shutter plate. Specifically, the bucket opens when the shutter plate rotates until its opening overlaps the opening in the bottom plate. Furthermore, a claw (stopper) is fixed to one side of the center of rotation of the straight edge of the shutter plate's opening 8 (located in the center of the straight edge), which strikes the straight edge of the opening in the bottom plate when the shutter plate rotates. To open the opening, the drilling bucket is rotated in the same direction as excavation. The claw of the shutter plate then receives a reaction force from the soil and sand, causing the shutter plate to rotate relative to the bottom plate, and the claw strikes the straight edge of the opening in the bottom plate, fully opening it. To close the opening, such as when lifting the bucket, the drilling bucket is rotated in the opposite direction, causing the shutter plate to rotate in the opposite direction, and the claw strikes the straight edge on the opposite side, fully opening it.

[0004] Also, a drilling bucket that has conventionally been used as a drilling bucket and includes a bucket body formed in a cylindrical shape and a bottom cover arranged on the bottom of the bucket body has been disclosed (see Patent Document 2). The bottom cover includes a slit, a plurality of cutter bits arranged in a row along the slit, and a plurality of cutter bits arranged in a row so as to protrude downward along an edge portion, and the bottom cover is formed so as to be inclined such that a center portion of the bottom cover is higher than the edge portion and so as to protrude downward.

[0005] The drilling bucket is said to use a slitting bit to cut away the natural ground that has penetrated into the bottom of the bucket, and to take it into the bucket body through the slit. The slit is also said to have a plurality of slitting bits (cutter bits) arranged along its edge. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 63-005550 [Patent Document 2] Special publication No. 5193084 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] However, in the conventional casing head, the crushing screw head and the fragment collection arm are separate devices, so it was necessary to crush the material with the crushing claws, collect the crushed fragments, and then insert the collection arm back into the hole to perform the work. As a result, it was not possible to say that the crushing efficiency was good, and it was also not possible to say that the fragment collection efficiency was good.

[0008] Therefore, an object of the present invention is to provide a casing device that has high crushing efficiency and high crushed fragment recovery efficiency. [Means for solving the problem]

[0009] The following measures have been taken to solve the above problems. Note that, including in the following sections, the numbers or combinations of numbers and letters written after each term are reference symbols for convenience in referring to the drawings shown as examples, and do not themselves limit the concept or form.

[0010] [1] The casing for forming a pile hole of the present invention is a cylindrical casing 10 having plate-blade-like crushing claws 11C arranged along the circumferential shape of the cylindrical end, and three spirally or obliquely advancing screw blades 2 fixed integrally to the inner surface of the cylindrical casing near the end of the casing, The three screw blades 2 are gathered in the axial direction (with an inclined plane or a twisted curved surface as a plate surface), and a short shaft column 3 having a height equal to or less than the height of the cylindrical casing is integrally held and fixed at the center of the gathered cylindrical shaft at a coaxial position with the casing, A plurality of bits 12B each having a pointed rotor are arranged along a side edge (a side edge of a lower side surface) near the rotation direction of the screw blade 2, which extends toward the shaft center along the casing end direction, with the tip of each bit 12B protruding beyond the side edge of the screw blade 2; The three screw blades 2 are full-blade screws or flat-blade screws in which the upper surface 2T and the lower surface 2B of each blade advance obliquely toward the center of the cylindrical axis along a predetermined axial height in the casing end direction, and at least a part of the inner side of the blade is fixed to the peripheral side of the short shaft column 3 with a fixing line oblique to the axial direction, The multiple bits 12B are each interchangeably attached to the axial hole of a bit holder fixed to the blade side end of each screw blade or in the vicinity thereof, and the tip of each bit protrudes from the lower edge of the blade of each screw blade, and is arranged in a spiral radial pattern from the center to the periphery so that the tips of all the bits except the outermost bits of each blade have different diameters when viewed from the bottom.

[0011] With this configuration, the crushed pieces are crushed by the plate-blade-shaped crushing claws 11C formed along the end of the tube, and then collided with the bits at the tips of the screw blades inside the tube, thereby performing two-stage crushing and reducing the crushed particles into fine particles.

[0012] Three or more bits are attached to each screw blade, arranged so that they intersect the direction of the lower edge of the blade and their tips protrude from the lower edge of the blade.

[0013] In addition, as the casing rotates, the spiral screw blades 2 that make up the blade screw rotate around the short axis, and the crushed pieces are picked up by the blade surface of the screw blades 2, transported by conveyor, and concentrated around the short axis column 3.

[0014] [2] At or near the lower edge of each of the three screw blades, a plurality of bit holders (12H) are fixed in a spaced arrangement along the side direction of the lower edge of the blade (2), Each bit holder 12H is configured to have a holding shaft hole corresponding to the bit shaft portion of each bit, In addition, each of the bits 2B is integrally formed with a thin bit shaft portion and a rotating bit portion having a conical bit tip, The bit shank of the corresponding bit 2B is supported one by one in an exchangeable manner in the axial hole of each bit holder, and each bit is held so as to be freely rotatable around the bit shank.

[0015] [3] A portion of the inner edge of each of the three screw blades 2 is partially cut out on the plate edge corresponding to the upper side surface and its surroundings so that there is a gap (BS) with respect to the short column axis, and crushed pieces larger than the remaining blade width that have been partially cut out can be re-crushed by falling back down. This type of structure makes it less likely for debris to become clogged. In other words, if the opening space excluding the blades is narrow when viewed from the bottom, the debris gets caught on the spiral blades and rotates with the casing, preventing the blades from advancing along the conveyor and preventing the discharge of debris (soil and crushed rock) generated by rotary excavation. By contrast, by providing a gap, the debris does not get caught and does not rotate with the casing, improving discharge efficiency.

[0016] [4] The tip (bit tip) of the conical bit tip of any one or more of the multiple bits B is characterized in that, when held in the bit holder BH, it protrudes axially further than the short shaft column 3 inside the casing.

[0017] [5] Furthermore, it is preferable that the tip of the bit furthest in the axial direction is flush with the tip of the casing or protrude slightly beyond it. By lowering the position of the bit toward the tip in the figure, continuous crushing within the tube becomes possible near the tip of the casing, allowing the crushed rock to be efficiently discharged, improving drilling efficiency.

[0018] However, the multiple bits are arranged radially and in a funnel shape when viewed from the tip to the base end, and of these multiple bits, only the tips of one or two bits closest to the central tip are flush with or protrude from the tip of the casing tube, while the remaining majority of bits are arranged within the tube with their bit tips lower toward the base end than the casing end.

[0019] In addition, multiple protective blocks 4 protruding from part of the cylinder periphery toward the axial center may be fixed to the inner surface of the casing cylinder, axially above the short shaft column (towards the cylinder base, opposite the cylinder end) (Figs. 6 and 7). The protective blocks 4 can protect the grab head from hitting the blade when it is dropped (Fig. 8).

[0020] The protection blocks 4 are composed of a plurality of blocks that are curved, approximately rectangular parallelepipeds, with arc-shaped inner sides in a plan view so as not to impede soil removal efficiency (Figs. 6 and 7). The upper and lower surfaces of the block bodies 4 are made up of upper and lower inclined surfaces 41, respectively, and the height of the inner surface closer to the central axis is set smaller than the height of the outer surface in contact with the cylindrical inner surface, giving the block bodies a trapezoidal cross-sectional shape in a side view. In Example 2, the protection blocks are arranged at equal intervals with equal-phase gaps at positions that divide the cylindrical cross section of the casing into 6 to 8 equal parts in the circumferential direction (Figs. 6 and 7). [Effects of the Invention]

[0021] The above means provide a casing device that has high crushing efficiency and high crushed fragment recovery efficiency. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a side view of a casing for forming a pile driving hole according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a bottom view of the casing for forming a pile driving hole according to the first embodiment. [Figure 3] Bottom view of Figure 2, cross section AA [Figure 4] FIG. 2 is a plan view of the casing for forming a pile driving hole according to the first embodiment. [Figure 5] FIG. 2 is a cross-sectional side view illustrating the use state of the casing for forming a pile hole according to the first embodiment. [Figure 6] FIG. 10 is a side view of the casing for forming a pile driving hole according to the second embodiment. [Figure 7] FIG. 10 is a plan view of a casing for forming a pile driving hole according to a second embodiment. [Figure 8] FIG. 10 is a cross-sectional side view illustrating the use state of the casing for forming a pile hole according to the second embodiment. [Figure 9] FIG. 10 is a bottom view of a casing for forming a pile driving hole according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional side view of a casing for forming a pile driving hole according to a third embodiment. [Figure 11] FIG. 10 is a side view of a casing for forming a pile driving hole according to a fourth embodiment of the present invention. [Figure 12]FIG. 10 is a bottom view of the casing for forming a pile hole according to the fourth embodiment. [Figure 13] FF cross section of Figure 12 [Figure 14] FIG. 5 is a side cross-sectional view of a casing for forming a pile driving hole according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, the casing for forming a pile driving hole of the present invention and the method for discharging crushed fragments during formation of a pile driving hole using the same will be described with reference to the drawings showing embodiments of the present invention.

[0024] In all embodiments, the pile driving hole forming casing of the present invention is used to form pile driving holes, and is attached to the tip of a cylindrical casing tube PP suspended from the tip of the boom of an earth boring machine.Even if there is bedrock underground, it will excavate a vertical pile driving hole while destroying the bedrock, and will also remove bedrock R or soil from the bottom of the hole (for example, Figures 5 and 8).

[0025] Its basic configuration includes a cylindrical body (100, 500) having the same diameter as the casing tube PP and connectable to the lower end of the casing tube PP, and a cylindrical casing 10 having a number of plate-shaped crushing claws 11C arranged along the circumferential shape of the lower cylindrical end of the cylindrical body; three screw blades 2 fixed to the inner surface of the cylinder near the end of the casing at equal central angular intervals around the circumference of the cylinder, converging from the fixed part on the circumference of the cylinder toward the center of the cylinder axis, and spiraling downward in the direction of the cylinder axis within the cylinder; A plurality of bits 12B each consisting of a pointed rotating body, which are arranged and protrude along a side edge (a side edge of a lower side surface) closer to the rotation direction of the screw blade 2 extending toward the shaft center along the casing end direction; It is composed of a short shaft pillar 3 that extends coaxially with the casing and is located in the center of the cylindrical shaft, where the three screw blades 2 are concentrated, and is held and fixed by the inner surface of the screw blades 2 along which they spiral.

[0026] Of these, at least the lower part of the cylindrical casing 10, the three screw blades 2, and the short shaft column 3 are integrally formed by welding and fixed together, and rotate integrally when excavating a pile hole.

[0027] (Screw blade 2) The three screw blades 2 are all made of blade plates of the same approximately sectorial or rectangular shape, and in an orthogonal cross section of the cylindrical casing 10 (for example, a cross section taken along the bottom surface in FIG. 2 or the top surface in FIG. 4), the three blades are arranged on three sides around the center, which is the cylindrical axis, at equal central angular intervals, and the outer peripheral side surfaces of the three blade plates are fixed to various parts of the inner surface of the cylindrical body, which divides the cylindrical circumference into three parts. The three screw blades 2 arranged on three sides around the cylindrical center each extend linearly or curvedly from various parts of the cylindrical inner surface toward the axial center and downward, and are centrally gathered, and a common short shaft column 3 is supported from three directions at the centrally gathered center of the cylindrical axis. The upper and lower surfaces of each blade form a common inclined plane that is inclined at a predetermined angle in a predetermined direction with respect to the horizontal plane in the extension direction, and the three blades are oriented symmetrically around the central axis. As a result, gaps BS between the blades are formed at equal intervals around the central axis in a plan view (for example, FIG. 4).

[0028] (Bit 12B, end bit 12BT, rear bit 13B) A plurality of bits 12B each having a pointed rotor are arranged in series along the blade side of the screw blade that spirally advances toward the shaft center along the casing end direction, with the tip of the bit protruding beyond the blade side, The blade surface of the screw blade 2 advances spirally toward the center of the cylindrical shaft along a predetermined axial height toward the casing end, Four or more of the plurality of bits are rotatably attached so that they intersect with the direction of the lower side of each screw blade and have their tips protruding from the lower side of the blade.

[0029] Each bit 12B, 12BT, 13B is rotatably held by a bit holder 12H. That is, a plurality of bit holders 12H having short shaft holes are fixed near the lower edge of each of the three screw blades, with the plurality of bit holders fixed at intervals along the length of the lower edge. The bits 2B are each integrally formed of a thin bit shaft portion and a rotating bit portion, The bit shaft of each bit is shaped to correspond to the short shaft of the bit holder. By being supported by each bit holder, each bit 12B is held so as to be freely rotatable around its corresponding bit axis.

[0030] (Short axis column 3) A total of three screw blades 2 arranged on three sides around the center of the cylinder are twisted together in the axial direction, and a short shaft column 3, whose height is equal to or less than the height of the cylindrical casing, is held and fixed integrally with the casing in the coaxial direction at the center of the cylinder shaft, which is the gathering point.

[0031] The short shaft pillar 3 has a cylindrical diameter of about one-fifth to one-sixth the inner diameter of the cylindrical body and is a short pillar with a height equal to or less than the cylindrical height of the cylindrical casing, and three spirally advancing screw blades 2 are fixed to the peripheral side of the pillar. The upper surface 3T of the short shaft pillar 3 is a substantially horizontal plane, and is designed to carry the discharged blocks (excavated blocks of rock and earth and sand generated by excavation) collected from the upper surface of the blades by the rotation of the screw blades 2.

[0032] The crushed pieces crushed by the plate-blade crushing claws 11C are collided with the bits at the tips of the screw blades inside the cylinder, thereby performing two-stage crushing and reducing the crushed particles to finer particles.

[0033] Furthermore, as the casing rotates, the crushed pieces are picked up by the screw blades 2 and transported in a spiral motion, being placed on the blade surface and then concentrated around the short shaft column 3.

[0034] Example 1 1 to 5, the casing for forming a pile hole according to the first embodiment is configured as a connected body in which an upper cylindrical body 50 and a lower cylindrical casing 10 are fitted together using fitting projections 12 and fitting holes 51, and are connected vertically using a connecting cap CP. Fitting projections 53 and a slightly smaller diameter short cylinder 52 formed on the outer periphery at the upper end of the upper cylindrical body 50 are fitted onto the lower end of the casing tube PP, and the short cylinder 52 is fixed to the casing tube PP by fixing holes 54 formed at equal intervals around the circumference of the short cylinder 52.

[0035] The crushing claw 11C of Example 1 is made of a roughly trapezoidal plate blade, the upper part of which is fixed to the lower cylindrical body by a pin hole, and the lower tip of which has an inclined blade 12C with a uniform angle that protrudes downward from the lower end of the lower cylindrical casing 10.

[0036] In addition, the screw blade 2 of Example 1 consists of a spiral blade that progresses from the top to the bottom in the axial direction, and is composed of a spiral curved surface plate surrounded by four sides: an inner side surface fixed to the short shaft column 3 at the axial center, an outer side surface fixed to the lower cylindrical body at the circumferential portion, an upper side surface extending linearly in the radial direction at the upper axial direction, and a lower side surface extending curvedly in the radial direction at the lower axial direction, and is approximately fan-shaped when viewed in a plane.

[0037] Of the four side surfaces, the inner peripheral side surface is fixed obliquely along the column side surface from the upper end to the lower end of the column side surface of the short-axis column 3. Furthermore, of the four side surfaces, the outer peripheral side surface is fixed obliquely along the inner surface of the lower cylindrical casing 10, from the top to the bottom of the center in the height direction of the lower cylindrical casing 10 (FIGS. 1 to 3). Furthermore, of the four side surfaces, the upper side surface forms a straight line inclined clockwise by a predetermined phase angle from the radial direction of the upper cylinder in the plan view of FIG. 4, and forms a straight line inclined by a predetermined inclination angle from the horizontal direction perpendicular to the axis in the front cross-sectional view of FIG. 3. Furthermore, the lower side of the four side surfaces forms a curved line shape that gradually retreats clockwise from the center toward the outer periphery by a predetermined phase angle from the radial direction of the upper cylinder when viewed from the top in FIG. 4, and also forms a curved line shape that gradually retreats upward from the center toward the outer periphery while being inclined by a predetermined inclination angle from the horizontal direction perpendicular to the axis when viewed from the front cross section in FIG.

[0038] The upper blade surface 2T of the screw blade plate surrounded by the four side surfaces is formed of a concave spiral curved surface with a relatively large twist near the inner peripheral side surface and a relatively small twist near the outer peripheral side surface, and has a substantially fan shape when viewed from the bottom in Fig. 2 and in the plan view in Fig. 4. A blade reinforcing plate 22, also having a curved surface, is surface-fixed to the upper half of the lower blade surface in the axial direction, thereby forming a double plate.

[0039] Seven bit holders 12BH are fixed at approximately equal intervals along the lower side surface of the screw blade 2, and bits 12B, 12BT are inserted and fitted into each bit holder 12BH so that they can rotate freely, forming a bit row 12BG. The bits 12B forming a row in the bit row 12BG and the end bits 12BT on the lower cylindrical surface 3E of the short cylinder 3 are each oriented so that they face outward from the side surface, approximately perpendicular to the lower side surface, when viewed from the bottom (FIG. 2), and face diagonally downward when viewed from the front cross section (FIG. 3), with the angle between adjacent bits slightly changing. The bit rows 12BG of each screw blade are arranged in order on a spiral row line in a plan view, from a position near the center to a position near the outer periphery, and the end bit closest to the axial end of each bit row is adjusted to the same position as the cylindrical tip of the casing.

[0040] A rear bit holder 13H is fixed to the underside of the blade at a position that is retreated from the outer peripheral side surface by a phase angle toward the rear of the row of bits 12BG in the direction of rotation, and the rear bit 13B is inserted and fitted into this rear bit holder. This fitting allows the rear bit 13B to be freely rotatable around the axis and to be removable and replaceable.

[0041] 1 to 5, the bits 12B constituting the bit row 12BG of Example 1 are arranged in order from the bit closest to the axial center to the bit closest to the inner periphery of the cylinder, with the tips of the bits arranged in a row direction that gently curves in a convex shape along the lower side surface of the screw blade, from the lower side near the axial center to the upper side near the outer periphery. Furthermore, at an extension position further forward and toward the central axis than the bit 12B closest to the center of the bit row 12BG, the end bit 12BT that protrudes most downward is fitted and inserted into a bit holder and arranged on the surface of the lower cylindrical surface 3E of the short cylinder 3.

[0042] The tips of the bits 12B01 to 12B21, the end bit 12BT, and the rear-bent rear bit 13B that make up the bit string 12BG are arranged in a spiral shape from the axial center toward the outer periphery when viewed from the bottom, with the radial distance from the center gradually increasing. That is, the tips of these bits 12B01 to 12B21, the end bit 12BT, and the rear-curved rear bit 13B are positioned between the three screw blades with a slight radial distance from the center, whether viewed from the bottom or in a front cross-sectional view, and all the bit tips are positioned with a slight radial distance from the center gradually decreasing in axial position from the lower to the upper positions.

[0043] For example, when the three screw blades are arranged in the rotational direction of the cylindrical body as a first screw blade, a second screw blade, and a third screw blade, the bit tip 12B01 of the bit row of the first screw blade, which is closest to the axial center, is set to have the smallest inner radial distance. Next, the bit tip 12B02 of the bit row of the second screw blade, which is closest to the axial center, is set to have the second smallest inner radial distance after the bit tip 12B01. Next, the bit tip 12B03 of the bit row of the third screw blade, which is closest to the axial center, is set to have the third smallest inner radial distance after the bit tip 12B02 of the adjacent second screw blade.

[0044] These bit tips 12B01, 12B02, and 12B03 protrude axially downward in the same order in a front cross-sectional view. That is, 12B01 is located furthest axially downward, 12B02 is located second furthest axially downward, and 12B03 is located third furthest axially downward.

[0045] Furthermore, the bit tip 12B04 of the bit row of the first screw blade, which is second from the axial center, is set to have the fourth smallest inner radial distance after the bit tip 12B03 of the adjacent third screw blade, which is located in a phase closer to the rear in the rotational direction. Furthermore, the bit tip 12B05 of the bit row of the second screw blade, which is second from the axial center, is set to have the fifth smallest inner radial distance after the bit tip 12B04 of the adjacent first screw blade, which is located in a phase closer to the rear in the rotational direction. Furthermore, the bit tip 12B06 of the bit row of the third screw blade, which is second from the axial center, is set to have the sixth smallest inner radial distance after the bit tip 12B05 of the adjacent second screw blade, which is located in a phase closer to the rear in the rotational direction.

[0046] These bit tips 12B01, 02, 03, 04, 05, and 06 protrude downward in the axial direction in the same order in a front cross-sectional view. That is, 12B01 is located furthest downward in the axial direction, 12B02 is located second most downward in the axial direction, 12B03 is located third most downward in the axial direction, and so on, with the remaining bit tips 12B01, 12B02, 12B03, and 12B06 located fourth, fifth, and sixth most downward in the axial direction, respectively.

[0047] In addition, the radial distance relationships and axial positional relationships are such that all bits, including the end bits 12BT1, 2, 3 of the first, second, and third screw blades, the bit rows 12BG, 12BG, 12BG of the first, second, and third screw blades, and the rear bits 13B of the first, second, and third screw blades, are arranged in stages in the same order from the center to the periphery. As a result, by rotating the three screw blades in conjunction with the rotation of the cylindrical body, the bits hit the underground rock in order from the center axis to the periphery axis, enabling staged excavation with a time lag.

[0048] A total of three gaps BS are formed between the three screw blades in plan and bottom views. As the rock is broken at each bit, rock fragments and earth and sand are scooped up by the screw blades from each gap BS and placed on the upper surface of the blades as the casing of the present invention rotates together with the casing tube PP. The rock fragments BR1 generated by excavating the underground rock mass R are then transported axially upward by the screw in the internal space 100 of the lower cylindrical casing 10, and are loaded upward from the top surface of the short shaft column 3 and into the internal space 500 of the upper cylindrical body 50 (Figure 5). The crushed rock fragments BR1 loaded in this internal space 500 are removed from the casing tube PP by the hammer head GBH of the grab hammer GB inserted into the casing tube PP and collected above the ground surface (Figure 5).

[0049] Of the multiple bits arranged in order on a spiral line in a planar view from a position closer to the center to a position closer to the outer periphery, the tip of the bit furthest axially is flush with the tip of the casing tube or protrudes slightly beyond it.

[0050] A portion of the inner edge of each of the three screw blades is cut in a straight or curved shape to leave a gap in relation to the short column axis, allowing any crushed pieces larger than the width of the remaining cut blade to fall back through the gap and be crushed again.

[0051] Example 2 In the pile-driving hole forming casing of Example 2 shown in Figures 6 to 8, a plurality of protruding blocks 4 protruding from a portion of the periphery of the cylinder toward the axial center are fixedly attached to the inner surface of the casing, axially above the short shaft pillar (toward the cylinder base, opposite the cylinder end). These protruding blocks protect the internal mechanism consisting of the screw blades 2 and short pillars 3 from falling objects inside the cylinder. For example, if a grab hammer GB is dropped into the casing tube PP, the multiple protruding blocks protruding from the axial center will interfere before colliding with the internal mechanism of the screw blades 2 and short pillars 3, preventing damage to the internal mechanism by the falling object.

[0052] In a cylindrical casing 10 having blade-like crushing claws 11C arranged along the circumference of the cylindrical end, three spirally advancing screw blades 2 are integrally fixed to the inner surface of the cylindrical casing near the end of the casing, A short shaft column 3 having a height equal to or less than the height of the cylindrical casing is integrally held and fixed in the same axial direction as the casing at the center of the cylindrical shaft where the three peripheral screw blades 2 are twisted and gathered in the axial direction, A plurality of bits 12B each having a pointed rotor are arranged in series along the blade side of the screw blade that spirally advances toward the shaft center along the casing end direction, with the tip of the bit protruding beyond the blade side, The blade surface of the screw blade 2 advances spirally toward the center of the cylindrical shaft along a predetermined axial height toward the casing end, Four or more of the plurality of bits are rotatably attached so that they intersect with the direction of the lower side of each screw blade and have their tips protruding from the lower side of the blade.

[0053] Furthermore, a plurality of protruding blocks 4 are fixedly mounted on the inner surface of the casing, axially above the short shaft column (towards the base of the cylinder, opposite the end of the cylinder), protruding from a part of the circumference of the cylinder towards the center of the axis.

[0054] In Example 2, the multiple bits arranged along the blade side of each screw blade form a bit row arranged in order on a spiral line in a plan view from a position closer to the center to a position closer to the outer periphery. Of the three bit rows, the end bit 3BT located at the most axially distal end of one bit row is set at the same position as the cylindrical tip of the casing, and the tips of the remaining bits are all located inside the cylindrical casing. Furthermore, the bit tip positions of the end bits 3BT of the remaining second and third bit rows are adjusted in order axially upward relative to the end bit 3BT of the first bit row, and further, the bit tips of the first bit row and the second and third bit rows are adjusted to be axially upward in order, starting from the position closest to the axial center.

[0055] Example 3 In the pile hole forming casing of Example 3 shown in Figures 9 and 10, the outer peripheral side surface 2E of the screw blade 2 is welded and fixed to the inner surface of the cylindrical casing 10, the upper side surface of the screw blade 2 is cut horizontally so that it faces horizontally in a front cross-sectional view, and a reinforcing plate 22 is welded to the underside of the blade in the area of ​​the upper one-third of the screw blade 2 near the upper side surface. In addition, the tips of two bits of the bit row 12BG that are closer to the axial center protrude downward from the bottom end of the cylinder. However, the protrusion of these bit tips is such that they are positioned axially above the cutting edge 11C of the crushing claws 11, and do not protrude downward beyond the tip of the cutting edge 11C.

[0056] In addition, unlike the first embodiment, the end bit 12BT is not provided on the lower column surface 3E of the short cylinder 3. Otherwise, the basic configuration is the same as that of the first embodiment.

[0057] Example 4 In the casing for forming a pile hole of Example 4 shown in Figures 11 to 13, the blade surfaces of the three screw blades 2 advance obliquely toward the center of the cylindrical axis along a predetermined axial height toward the end of the casing, and at least a portion of the inner edge of the blade is fixed to the peripheral side of the short shaft column 3, making up a flat blade screw.

[0058] The screw blade 2 is composed of a rod-shaped blade that is rectangular in plan and bottom views. The blade surface of the rod-shaped blade is inclined relative to the axial direction in a front cross-sectional view, and is inclined toward the central protrusion so that it is positioned axially downward from the outer circumferential side toward the axial center. The lower side of the rod-shaped blade is flat. Multiple bit holders are fixed along this flat lower side, with their respective protrusion amounts, central positions, and forward directions offset from adjacent ones, forming a bit row with bits inserted into each bit holder. In addition, bit holders for end bits 12BT01, 02, and 03 are fixed to the underside of the rod-shaped blade, even closer to the axial center than the bit closest to the axial center in the bit row. The bit strings of these end bits 12B01, 12B02, 12B03 and bits 12B04, 12B05, 12B06, . . . 12B15 are arranged in a spiral shape extending from the axial center toward the outer periphery in a bottom view, with the radial distance from the center increasing stepwise.

[0059] However, there is no upper cylinder body or rear bit as in Example 1. The other basic configurations and usage methods are the same as in Example 1.

[0060] Example 5 In the pile hole forming casing of Example 5 shown in Figure 14, the lower end of the short cylinder 3 is formed at the same axial position as the lower end of the cylindrical body, and an end bit 12BT is provided on the lower cylindrical surface 3E of the short cylinder. As with Example 4, the screw blade 2 of Example 5 consists of a rod-shaped blade that is rectangular in plan and bottom views, and the blade plate surface of the rod-shaped blade is inclined with respect to the axial direction in a front cross-sectional view and is inclined toward the central protrusion so that it is positioned axially downward from the outer peripheral side toward the axial center. The lower side surface of the rod-shaped blade is flat.

[0061] The other configurations and methods of use that are not otherwise specified are the same as those in the fourth embodiment.

[0062] The casing for forming a pile hole of the present invention described above is a cylindrical casing 10 having blade-like crushing claws 11C arranged along the circumference of the cylindrical end, and three spirally or obliquely advancing screw blades 2 fixed integrally to the inner surface of the cylindrical casing near the end of the casing, and further The three screw blades 2 are gathered in the axial direction (torsionally gathered or reverse radially), and a short shaft pillar 3, the height of which is equal to or less than the height of the cylindrical casing, is integrally held and fixed coaxially with the casing in the center of the cylindrical shaft. A bit row, consisting of a row of pointed bits, is formed protrudingly near the side of each screw blade 2 in the forward direction of rotation. This integrated casing body is connected to the bottom of the casing tube and driven to rotate, causing each bit to collide with stones or bedrock underground, starting with the bit tip closest to the central axis, and progress while excavating the ground.

[0063] A plurality of bits 12B each made of a pointed rotor are arranged along the side of the screw blade 2, which advances spirally toward the shaft center along the casing end direction, with the tip of each bit 12B protruding beyond the side of the screw blade 2. The three screw blades 2 are full-blade screws or flat-blade screws in which each blade plate surface 2T advances obliquely toward the center of the cylindrical axis along a predetermined axial height in the casing end direction, and at least a part of the inner edge of the blade is fixed to the peripheral side surface of the short shaft pillar 3 (by a spiral fixing line), The multiple bits 12B are each interchangeably attached to the axial hole of a bit holder fixed to the blade side end of each screw blade or in the vicinity thereof, and the tip of each bit protrudes from the lower edge of the blade of each screw blade, and is arranged in a spiral radial pattern from the center to the periphery so that the tips of all the bits except the outermost bits of each blade have different diameters when viewed from the bottom.

[0064] With this configuration, the crushed pieces are crushed by the plate-blade-shaped crushing claws 11C formed along the end of the tube, and then collided with the bits at the tips of the screw blades inside the tube, thereby performing two-stage crushing and reducing the crushed particles into fine particles.

[0065] The bits are attached to each screw blade in a state where they intersect with the direction of the lower edge of the blade and are lined up so that their tips protrude from the lower edge of the blade, and three or more bits are attached to each screw blade, forming a row of bits that each protrude by a predetermined amount from a specific side surface forward in the rotation direction of the blade plate.

[0066] In addition, as the casing rotates, the spiral screw blades 2 that make up the blade screw rotate around the short axis, and the crushed pieces are picked up by the blade surface of the screw blades 2, transported by conveyor, and concentrated around the short axis column 3.

[0067] [2] At or near the lower edge of each of the three screw blades, a plurality of bit holders (12H) are fixed in a spaced arrangement along the side direction of the lower edge of the blade (2), Each bit holder 12H is configured to have a holding shaft hole corresponding to the bit shaft portion of each bit, In addition, each of the bits 2B is integrally formed with a thin bit shaft portion and a rotating bit portion having a conical bit tip, The bit shank of the corresponding bit 2B is supported one by one in an exchangeable manner in the axial hole of each bit holder, and each bit is held so as to be freely rotatable around the bit shank.

[0068] [3] A portion of the inner edge of each of the three screw blades is partially cut to leave a gap (BS) in relation to the short column axis, allowing fragments larger than the width of the remaining cut blade to fall back down and be re-crushed. This type of structure makes it less likely for crushed debris to become clogged. In other words, if the opening space excluding the blades is narrow when viewed from the bottom, the crushed debris will get caught on the spiral blades and rotate with the casing, preventing the blades from moving along the conveyor and preventing the excavated material (soil and crushed rock) from being discharged by rotation. By providing a gap, however, the debris will not get caught and will not rotate with the casing, improving discharge efficiency. [4] The tip of the conical bit tip of any one or more of the plurality of bits is characterized in that, when held in the bit holder, it protrudes axially further than the short shaft column 3 inside the casing. [5] Furthermore, it is preferable that the tip of the bit furthest in the axial direction is flush with the tip of the casing or protrude slightly beyond it. By lowering the position of the bit toward the tip in the figure, continuous crushing within the tube becomes possible near the tip of the casing, allowing the crushed rock to be efficiently discharged, improving drilling efficiency.

[0069] However, the multiple bits are arranged radially and in a funnel shape when viewed from the tip to the base end, and of these multiple bits, only the tips of one or two bits closest to the central tip are flush with or protrude from the tip of the casing tube, while the remaining majority of bits are arranged within the tube with their bit tips lower toward the base end than the casing end.

[0070] In addition, multiple protective blocks 4 protruding from part of the cylinder periphery toward the axial center may be fixed to the inner cylinder surface of the casing, axially above the short shaft column (towards the cylinder base, opposite the cylinder end). The protective blocks 4 can protect the grab head from hitting the blade when it is dropped.

[0071] The protection blocks are composed of a plurality of block bodies, each of which has a curved, approximately rectangular parallelepiped shape with arc-shaped inner sides in a plan view so as not to impede soil discharge efficiency. The upper and lower surfaces of the block bodies are each composed of an upper inclined surface and a lower inclined surface, and the height of the inner surface closer to the central axis is set smaller than the height of the outer surface in contact with the cylindrical inner surface, giving the block body a trapezoidal cross-sectional shape in a side view. In Example 2, the protection blocks are installed at equal intervals with equal-phase gaps at positions that divide the cylindrical cross section of the casing into 6 to 8 equal parts in the circumferential direction.

[0072] In addition, various modifications are possible within the scope of the essence of the present invention, such as extracting some parts, separating each part, replacing parts with other shapes, increasing or decreasing the number, and adjusting or changing the angle. [Explanation of symbols]

[0073] Cylindrical casing 10 Crushing Claw 11C Screw blade 2 Blade top surface 2T Bit 12B Bit holder 12H End bit 12BT Rear bit 13B Short axis column 3 Column surface 3E

Claims

1. In a cylindrical casing having plate-shaped crushing claws arranged along the circumference of the cylindrical end, three blade-shaped screw blades are integrally fixed to the inner surface of the cylindrical casing near the end of the casing, A short shaft pillar having a height equal to or less than the height of the cylindrical casing is held and fixed at the center of the cylindrical shaft where the three screw blades are gathered in the axial direction, at the axial center position within the cylindrical casing, at the gathering portion of the three screw blades; A plurality of bits each consisting of a pointed rotor are arranged along the side of the screw blade, which advances spirally toward the shaft center along the casing end direction, with the tip of each bit protruding beyond the side of the screw blade. The three screw blades are full-blade screws or flat-blade screws, each of whose blade surface advances obliquely toward the center of the cylindrical shaft along a predetermined axial height in the casing end direction, and at least a part of the inner edge of the blade is fixed to the peripheral side surface of the short shaft pillar 3; The plurality of bits are each replaceably attached to the axial hole of a bit holder fixed to the blade side end of each screw blade or in the vicinity thereof, and the tip of each bit protrudes from the lower edge of the blade of each screw blade, and is arranged in a spiral radial pattern from the center to the outer periphery so that the tips of all the bits are at different radial distances when viewed from the bottom.

2. A plurality of bit holders are fixed at intervals along the side direction of the lower side of each of the three screw blades at or near the lower side of the blade, Each bit holder is configured to have a holding shaft hole corresponding to the bit shaft portion of each bit, Each of the bits is integrally formed with a thin bit shaft portion and a rotating bit portion having a conical bit tip, A casing for forming a pile hole as described in claim 1, characterized in that the bit shank of a corresponding bit is supported one by one in an interchangeable manner in the axial hole of each bit holder, and each bit is held so as to be freely rotatable around the bit shank.

3. A casing for forming a pile hole as described in claim 1, characterized in that the pointed tip of any one or more of the bit portions of the plurality of bits protrudes axially further than the short shaft column inside the casing when held in the bit holder.

4. 2. A casing for forming pile holes as described in claim 1, wherein the plurality of bits lined up along the blade side edge of each screw blade are arranged in order on a spiral line in a planar view from a position closer to the center to a position closer to the outer periphery, and the tip of the bit furthest axially forward among the plurality of bits is either the same as the tip of the casing tube or protrudes slightly beyond the tip of the tube.

5. A casing for forming pile holes as described in claim 1, characterized in that a portion of the inner edges of each of the three screw blades is cut in a straight or curved shape so as to have a gap relative to the short column axis, and crushed fragments larger than the width of the remaining cut blades can be re-crushed by falling back through the gap.

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