JP6366028B1 - Drilling device and assembly method thereof - Google Patents

Abstract

An object of the present invention is to simply and reliably connect a ring bit and a casing shoe in an excavator. A casing shoe 8 joined to a lower end portion of a casing 7, a pilot bit 5 rotatably inserted into the casing 7 and the casing shoe 8, and attached to an outer peripheral portion of the lower end portion of the pilot bit 5 via a joint element Ring ring 6 to be provided. The ring bit 6 is inserted into the casing shoe 8 and has a cylindrical part 6b in which a groove part 6d is formed on the outer peripheral surface. The casing shoe 8 has an inner peripheral surface formed with a groove portion 8e that faces the outer peripheral surface of the tubular portion 6b of the ring bit 6 and is positioned opposite the groove portion 6d. The ring bit 6 and the casing shoe 8 are inserted between the groove portions 6d and 8e, and are connected to each other via a connecting member 10 that interferes with the groove portions 6d and 8e. [Selection] Figure 12

Description

  The present invention relates to a drilling device for driving a casing made of a steel pipe or the like while forming a hole in the ground, and an assembling method thereof.

  As a technique for driving a casing made of a steel pipe or the like while forming a hole in the ground, there is conventionally a so-called Clid method (commonly known as CRID method). Further, among the Clid method, the Nakabori method (DPR type), which uses the driven casing as the main pile while leaving it in the ground, has recently been used. This Nakabori construction method enables accurate and reliable pile laying and consolidation, and is excellent in that it can be smoothly placed on various grounds ranging from soft ground to cobblestones, boulders and bedrock layers. Have the advantages.

  In the Nakabori method, a ground auger as a rotational driving force source, a screw rod for transmitting the rotational driving force from the earth auger and discharging excavated soil, and the rotational driving force transmitted through the screw rod Generally, a drilling rig composed of a pilot bit for cutting the ground by a ring, a ring bit detachably connected to the pilot bit, a down-the-hole hammer used for driving, and a casing embedded as a pile is generally used.

  In order to perform a drilling operation using the excavator, it is necessary to erect the apparatus in a predetermined shape. In this installation work, an earth auger, screw rod, down-the-hole hammer and pilot bit are assembled into a predetermined shape assembly, and this is inserted into a casing that is erected almost vertically by a device fixing frame using a crane. It is performed by the procedure of doing.

  The assembly is provided with an earth auger at the top, a screw rod and a down-the-hole hammer connected below it, and a pilot bit attached below it. A casing shoe is joined to the lower portion of the raised casing by welding, and a ring bit is disposed at the lower end thereof.

  A pilot bit is attached to a lower end portion of the assembly inserted into the casing, and the pilot bit and a ring bit disposed below the raised casing are connected using, for example, a bayonet mount. , Connect (chuck) in a detachable and rotationally transmittable state.

  After the excavation device is erected by the series of operations, the earth auger is activated in a state where the excavator is aligned with the pile core, and the drilling operation is started. The rotational driving force of the earth auger is transmitted to the pilot bit and the ring bit through the screw rod, and the ground is excavated by the cutting action of the drill piece provided at the tip of the rotating pilot bit and the ring bit. The excavated ground soil is sent upward by a screw rod and pressurized air and discharged to the ground surface. Along with the excavation of the ground, a pressing force (driving force) is applied to the pilot bit using a down-the-hole hammer, so that a downward propulsive force is applied to the pilot bit and the drilling operation can be advanced more quickly. ing.

  When the ground is drilled to a predetermined depth by the drilling operation, the connection (chucking) between the pilot bit and the ring bit is released, and the pilot bit, screw rod and down-the-hole hammer are pulled out and these parts are collected. The casing and the ring bit are used as main piles while remaining in the ground.

  In order to smoothly and efficiently perform the standing work and the drilling work, the casing shoe and the ring bit joined to the lower end portion of the casing can be relatively moved (rotated and moved in the axial direction), and the shaft A structure (hereinafter simply referred to as an articulated structure) that is connected (not disengaged) in the direction is useful. Because, in order to efficiently embed the casing in the hole formed by the pilot bit and the ring bit, a mechanism for pulling the casing downward is required in conjunction with the speed at which the pilot bit and the ring bit form the hole. This is because the articulated structure is effective as a mechanism for that purpose. Further, according to the connecting structure, the screw rod and the pilot bit are inserted into the casing and the pilot bit is easily connected to the ring bit connected to the lower end of the casing during the standing operation. Because it can.

  As the excavator having the articulated structure, for example, the inventions described in Patent Documents 1 and 2 have existed conventionally. In this excavating apparatus as the prior art, a convex portion protruding from the inner peripheral surface of the casing shoe (13) welded to the lower end portion of the casing (12) and a convex portion formed on the outer peripheral surface of the ring bit (14). The above-mentioned connecting structure is realized by directly engaging with each other (see FIGS. 3 and the like of Patent Documents 1 and 2). Note that “19” shown in FIG. 3 of Patent Documents 1 and 2 is a buffer member, which is a member that is not directly related to the connecting structure between the casing shoe (13) and the ring bit (14).

JP2012-112160A JP 2013-108227 A

  However, a special structure such as a bayonet mount or a screw-in structure similar to the bayonet mount has been used for the articulating structure included in the excavating apparatus described in Patent Documents 1 and 2. For this reason, there has been a problem that both the ring bit and the casing shoe need to be subjected to complicated processing.

  The present invention was created in view of the problems of the prior art described above, and its purpose is to provide a ring bit and a casing that move relatively (relative rotation and relative movement in the axial direction) while having a simple and inexpensive structure. It is an object of the present invention to provide an excavating apparatus and an assembling method thereof capable of reliably connecting a shoe without detaching in the axial direction.

In order to achieve the above object, the present invention provides a casing made of a circular pipe member extending vertically, a casing shoe made of a cylindrical member coaxially joined to the lower end of the casing, and rotatable to the casing and the casing shoe. The excavator includes a pilot bit to be inserted into a ring bit and a ring bit to be detachably attached to an outer peripheral portion of a lower end portion of the pilot bit via a joint element, wherein the ring bit is inserted into the casing shoe and has an outer periphery The casing shoe has a cylindrical portion having a first locking portion formed on a surface thereof, and the casing shoe is opposed to the outer peripheral surface of the cylindrical portion of the ring bit and is positioned to face the first locking portion. The ring bit and the casing shoe are located between the first locking portion and the second locking portion. Inserted and are relatively movably connected through interfere connecting member and the two locking portions, further wherein the connecting member is made of an annular wire, on the inner peripheral side of the first engagement portion It is accommodated and the outer peripheral side is formed in the dimension accommodated in the said 2nd latching | locking part, It is characterized by the above-mentioned.
According to the present invention, the connecting member enables a relative connection (relative rotation and axial movement) between the ring bit and the casing shoe, and a reliable connection without disconnecting each other.
Further, according to the present invention, since the connecting member is simply inserted between the first locking portion formed on the ring bit and the second locking portion formed on the casing shoe, the creation thereof is easy. Can be done.
Furthermore, according to the present invention, the cylindrical portion of the ring bit that is the rotating element is located inside the casing shoe that is the non-rotating element, so that the portion of the outer peripheral surface of the ring bit that contacts the ground is the casing shoe of the ring bit. It becomes only the part of the short length which protrudes from the lower end of. For this reason, excavation resistance at the time of rotating a ring bit can be suppressed low, and it becomes possible to implement | achieve efficient excavation.

Furthermore, according to the present invention, it is possible to connect the ring bit and the casing shoe using a simple and inexpensive connecting member called a wire.

The present invention also relates to a method for assembling an excavator having the above-described characteristics, wherein a wire insertion hole extending from an outer peripheral surface of the casing shoe to the second engaging portion is opened in the casing shoe, and the casing is inserted into the wire insertion hole. The wire is inserted from the outside of the shoe, and the wire is mounted between the first locking portion and the second locking portion.
According to the present invention, it is possible to easily assemble the excavator simply by using a simple method of providing a wire insertion hole in a casing shoe and inserting a wire into the hole.

  According to the present invention, the ring bit and the casing shoe that move relative to each other with a simple and inexpensive structure can be reliably connected without coming off in the axial direction.

It is the schematic which showed the assembly procedure of the excavation apparatus 1 which concerns on this invention. It is the schematic which shows the state which assembled the excavation apparatus 1 which concerns on this invention. It is a bottom view of excavation equipment 1 concerning the present invention. It is sectional drawing (AA sectional drawing of FIG. 3) of the front-end | tip part of the digging apparatus 1 which concerns on this invention. 3 is a side view of a pilot bit 5. FIG. 3 is a plan view of a ring bit 6. FIG. It is sectional drawing (BB sectional drawing of FIG. 6) of the ring bit 6. FIG. 4 is a bottom view of the ring bit 6. FIG. 4 is a bottom view of the casing shoe 8. FIG. It is sectional drawing (CC sectional drawing of FIG. 9) of the casing shoe 8. FIG. 3 is a side view of the casing shoe 8. FIG. FIG. 5 is an enlarged cross-sectional view of a connecting portion between the ring bit 6 and the casing shoe 8 in FIG. 4. 3 is an enlarged cross-sectional view of a connecting portion between a ring bit 6 and a casing shoe 8. FIG. 2 is a plan view of a connecting member 10. FIG. FIG. 2 is a schematic longitudinal sectional view of a rotation stopping means arranged at the upper end portion of the excavator 1. 2 is a schematic cross-sectional view of rotation stopping means arranged at the upper end portion of the excavator 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. In addition, the upper and lower sides, right and left in the following description, and front and rear shall be defined based on the schematic diagram which shows the state which assembled | assembled the excavation apparatus which concerns on this invention shown by FIG. In addition, the vertical direction and the axial direction are synonymous unless otherwise specified.

  As shown in FIGS. 1 and 2, the excavation apparatus 1 according to an embodiment of the present invention discharges the excavated soil by transmitting the earth auger 2 as a rotation drive source and the rotation driving force of the earth auger 2. A screw rod 3 for driving, a down-the-hole hammer 4 used for driving, a pilot bit 5 having a drill piece for cutting the ground, a ring bit 6 detachably connected to the pilot bit 5, and a pile The excavator is composed of a casing 7 to be embedded and a casing shoe 8 joined to a lower end portion of the casing 7 by welding.

  The earth auger 2 is a component that functions as a rotational driving force source for excavation, and includes an electric motor (not shown) that generates the rotational driving force, a device frame 2b that accommodates the electric motor, and an electric motor The output shaft 2c is connected to the rotating shaft and extends downward. The output shaft 2c connected to the rotating shaft of the electric motor is connected to the upper end portion of the screw rod 3, whereby the pilot bit 5 attached to the lower end portion of the screw rod 3 and a ring connected to the pilot bit 5 so as to transmit the rotation. The rotational driving force is transmitted to the bit 6.

  The screw rod 3 is a component having a function of transmitting the rotational driving force generated by the earth auger 2 to the pilot bit 5 and the ring bit 6 and discharging the excavated waste soil to the ground surface. The rod portion 3a is made of a metal such as an alloy and extends vertically, and includes a helical screw portion 3b formed around the rod portion 3a. The upper end of the rod portion 3a is connected to the output shaft 2c of the earth auger 2, a down-the-hole hammer 4 is disposed below the screw rod 3, and a pilot bit 5 described later is attached to the lower end portion thereof. Yes. Here, the down-the-hole hammer 4 is a component for applying a pressing force (driving force) to the pilot bit 5 to give a downward driving force to the pilot bit 5 and thereby enabling quick and efficient drilling. is there.

  The pilot bit 5 is a component for excavating the ground and forming a drilling hole. The pilot bit 5 is made of a metal such as iron or an alloy thereof, and has a small diameter drive as shown in FIGS. The shaft portion 5a and a disk-like head portion 5b having a large diameter below the drive shaft portion 5a are configured.

  The drive shaft portion 5 a is connected to the rod portion 3 a of the screw rod 3, and has a structure in which the rotational driving force from the electric motor provided in the earth auger 2 is transmitted via the screw rod 3. Further, the drive shaft portion 5a is connected to the down-the-hole hammer 4 by, for example, spline fitting so as to be relatively movable in the vertical direction (axial direction).

  As shown in FIG. 3, the head portion 5 b is provided such that center-side drill pieces 5 c made of a large number of protruding members are scattered on the tip surface (lower end surface). The center side drill piece 5c is a part that rotates by the rotational driving force of the electric motor provided in the earth auger 2 transmitted through the drive shaft portion 5a and excavates the ground by the cutting action. As a result, the ground below the ground surface T is excavated to form a hole.

  Further, as shown in FIG. 5, the head portion 5b has a mount structure for connecting (chucking) with the ring bit 6 in a state where rotation can be transmitted to the outer peripheral surface (a bayonet mount structure which will be described in detail later). There is provided a locking notch 5g that constitutes a part of this. The locking cutouts 5g are arranged at, for example, six locations around the circumference at an equal interval of approximately 60 degrees, have openings that communicate with the discharge grooves 5e, and start from the openings. Is formed as a recess extending in a predetermined range in the direction opposite to the rotation direction of the electric motor (in FIG. 5, counterclockwise in plan view). The lock notch 5g has a vertically long rectangular shape in cross section and a horizontally long rectangular shape in a side view. Further, for example, the upper end is inclined inward and downward to improve assembly. doing.

  Further, as shown in FIGS. 4 and 5, the head portion 5b has a shoulder portion 5h that protrudes in a disk shape radially outward as a portion that receives a pressing force (driving force) from the down-the-hole hammer 4 at an upper portion thereof. Is formed. A lower end surface 5i of the shoulder portion 5h is opposed to an upper end surface 8c of a casing shoe 8 described later, and is configured to transmit a pressing force (driving force) from the down-the-hole hammer 4 to the upper end surface 8c.

  As shown in FIGS. 3 and 4, an air passage 5d extending substantially in the central axis direction is formed in the pilot bit 5. The air passage 5d is a passage for supplying pressurized air for pushing up the excavated soil upward, and extends along substantially the axial center of the drive shaft portion 5a and the head portion 5b. In the vicinity of the front end portion (lower end portion) of the portion 5b, it is branched into a plurality (four bodies). Further, each of these branch paths is formed so as to open at the front end surface (lower end surface) of the head portion 5b.

  As shown in FIGS. 3 and 4, a discharge groove 5e is extended radially outward from each opening of the air passage 5d branched into a plurality (four bodies). The plurality of discharge grooves 5e extend radially to the outer peripheral portion of the head portion 5b, and then extend upward along the outer peripheral surface of the head portion 5b, as shown in FIGS. An opening is provided at the upper end surface 5f of the head portion 5b. The opening of each discharge groove 5e in the upper end surface 5f communicates with the internal space 7a of the casing 7, and waste soil or the like generated by excavation is discharged by the compressed air supplied from the air passage 5d. It is configured to be discharged to the internal space 7a.

  The ring bit 6 is a component for excavating the ground directly under the casing 7, and is made of a metal such as iron and its alloy, for example, and as shown in FIGS. 6 to 8, a ring-shaped head portion 6a. And a cylindrical portion 6b having a cylindrical shape extending upward from the upper surface of the head portion 6a.

  The head portion 6a is a portion whose tip surface (lower end surface) is in contact with the ground, and an outer peripheral drill piece 6c for excavating the ground is provided at the outer peripheral edge of the tip surface (lower end surface). ing. Further, an end surface 6e facing the lower end of the casing shoe 8 described later in detail is provided on the upper surface of the head portion 6a. On this end surface 6e, a flat plate having a ring shape made of, for example, wood, hard rubber, or resin is used so as to fill a gap with the lower end (in other words, so as to contact the end surface 6e and the lower end). A member (buffer member 11 to be described later) is placed, and thereby designed to absorb an impact caused by a strong pressing force (driving force) from the down-the-hole hammer 4.

  As shown in FIGS. 4, 7 and 12, the outer peripheral surface of the head portion 6 a has a substantially cylindrical shape, but has a tapered shape in which the outer diameter gradually decreases from the bottom to the top. Since the outer peripheral surface of the head portion 6a is tapered, the close contact between the outer peripheral surface of the head portion 6a and the side surface of the drilling hole is avoided, thereby suppressing the action of earth pressure through the outer peripheral surface of the head portion 6a. The load applied to the excavation measure 1 is reduced.

  The cylindrical portion 6b is a portion that is inserted inside the casing shoe 8, and is a first locking portion (hereinafter referred to as a “groove portion”) 6d having a concave longitudinal section at an intermediate position on the outer peripheral surface thereof. Is formed in a ring shape over the entire circumference. The groove 6d is a part that houses a part of the connecting member 10 to be described later, the depth is smaller than the diameter of the connecting member 10, and the width H between the upper and lower sides (see FIG. 7) The member 10 is configured to have a predetermined dimension larger than the diameter of the member 10. The groove 6d is housed in a stable state by surrounding a connecting member 10 described later from three sides, but the aspect ratio is arbitrary. As will be described later, the width H dimension of the groove 6d may be determined from the viewpoint of the assembling property of the connecting member 10.

  Further, as shown in FIG. 6, the cylindrical portion 6 b is provided with a locking projection 6 f that forms a part of a bayonet mount that is detachably attached to the pilot bit 5 on the inner peripheral surface thereof. . For example, the locking projections 6f are arranged at six locations at equal intervals of, for example, approximately 60 degrees around the circumference, and the circumferential length L thereof is provided in the pilot bit 5 in order to ensure assemblability. It is designed to be less than the width of the discharge groove 5e. In addition, the vertical cross-sectional shape of the locking projection 6f has a substantially rectangular shape similar to the vertical cross-section of the locking notch 5g formed in the pilot bit 5. In order to improve the assembly property, for example, A chamfered portion 6g having an upper end inclined inward and downward is provided.

  The casing 7 is a component used as a main pile while standing on the ground surface T as it is after excavation. As shown in FIGS. 1 and 2, the casing 7 is formed of a metal such as iron or an alloy thereof, for example. It consists of a tubular steel pipe. As shown in FIG. 4, a casing shoe 8 is coaxially joined to the lower end portion of the casing 7 by welding, for example. Further, as will be described later, a screw rod 3 that is rotationally driven around a substantially central axis and a pilot bit 5 connected thereto are inserted into the hollow internal space 7a of the casing 7 during the drilling operation.

  The casing shoe 8 is a component to be joined to the lower end portion of the casing 7 and is formed of a cylindrical member made of a metal such as iron and its alloy, and is formed at the upper portion as shown in FIGS. A main body base portion 8a as a small-diameter cylindrical portion and a support portion 8b as a large-diameter cylindrical portion extending downward from the main body base portion 8a. In the present embodiment, in consideration of excavation resistance, a dimensional difference between the radius of the outer peripheral surface of the support portion 8b (large diameter cylindrical portion) and the radius of the outer peripheral surface of the main body base portion 8a (small diameter cylindrical portion) is, for example, It is designed to be substantially the same as the thickness of the casing 7.

  The main body base portion 8a is a portion to be inserted inside the lower end portion of the casing 7, and is welded W, for example, over the entire circumference on the outer peripheral surface facing the tip end of the lower end portion of the casing 7, as shown in FIG. The 4 and 10, the head portion 5b of the pilot bit 5 is accommodated inside the main body base portion 8a, and the upper end surface 8c thereof faces the lower end surface 5i of the shoulder portion 5h of the pilot bit 5. In addition, the pressing force (driving force) from the down-the-hole hammer 4 is received through the lower end surface 5i.

  The support portion 8b is a portion that accommodates the cylindrical portion 6b of the ring bit 6 so that it can be relatively moved (rotated and moved up and down) inside, and as shown in FIGS. The inner diameter is larger than the inner diameter of the inner peripheral surface of the main body base portion 8a, and a circular space surrounded by the lower end surface below the inner side surface of the main body base portion 8a formed thereby and the inner peripheral surface 8d of the support portion 8b, The cylindrical portion 6b of the ring bit 6 is accommodated.

  Further, as shown in FIGS. 4, 10, and 12, the longitudinal sectional shape is concave at an intermediate position of the inner peripheral surface 8 d of the support portion 8 b (a position facing the groove portion 6 d of the ring bit 6). A second locking portion (hereinafter referred to as “groove portion”) 8e is formed in a ring shape over the entire circumference. The groove 8e is a part that accommodates a part of the connecting member 10 described below, and the depth thereof is smaller than the diameter of the connecting member 10, and the width dimension between the upper and lower sides thereof is larger than the diameter of the connecting member 10. The size is large. The groove 8e is housed in a stable state by surrounding the connecting member 10 from three directions, but the aspect ratio is arbitrary.

  Further, as shown in FIGS. 9 and 10, a wire insertion hole (hereinafter referred to as “through hole”) 8f extending from the outer peripheral surface of the support portion 8b to the groove portion 8e is provided on the side wall of the support portion 8b. The through hole 8f is a hole for inserting the wire 10a as the connecting member 10 from the outside to the inside of the support portion 8b and mounting between the groove portion 6d and the groove portion 8e. In order to facilitate the mounting, the through-hole 8f has a ring-shaped groove 6d, 8e in a plan view so as to guide the inserted wire 10a in a substantially tangential direction of the ring-shaped groove 6d, 8e. It is formed so as to face a direction inclined obliquely toward the circumferential direction.

  Further, on the outer peripheral surface of the support portion 8b, as shown in FIGS. 9 to 11, a protrusion 8g extending in the vertical direction (axial direction) and projecting outward in the radial direction is, for example, approximately 45 around the circumference. It is arranged at eight places at equal intervals. By providing the projection 8g, the contact resistance between the casing shoe 8 and the ground increases, and the casing shoe 8 and the casing 7 joined thereto are shared by the pilot bit 5 and the ring bit 6 accommodated therein. The effect of preventing the rotation with the rotation is brought about. In view of the function, it is desirable to design the protrusion 8g so that the contact area between the protrusion 8g and the ground is as large as possible. For this reason, the form of the protrusion part 8g is not limited to this embodiment, You may provide more protrusion part 8g. Further, as the shape of the protruding portion 8g, various shapes such as a convex shape extending obliquely up and down, a curved convex shape, a cube, a rectangular parallelepiped, a hemispherical surface, and the like are conceivable. In consideration of the resistance during excavation, the outermost diameter of the protrusion 8g is required to be designed to be equal to or smaller than the outermost diameter of the ring bit 6.

A specific procedure for carrying out a drilling operation using the excavator 1 composed of the components will be described below.
First, as shown in FIG. 1, the device fixing frame body 9 is constructed on the ground surface T of the ground for drilling. An opening 9 a is opened at substantially the center of the device fixing frame 9.

  Next, the casing 7 is inserted into the opening 9a of the device fixing frame 9, and this is erected substantially vertically. Next, in the factory, the ring bit 6 can be relatively moved (rotated and moved up and down) by the connecting structure J, which will be described later, at the lower end of the casing shoe 8 and in a state in which they do not deviate in the vertical direction (axial direction). What has been attached is prepared, and the casing shoe 8 is joined to the lower end of the casing 7 by welding W.

  Here, the connecting structure J will be described. As shown in FIG. 12, the connecting structure J includes a groove 6d (first locking portion) formed in the tubular portion 6b of the ring bit 6 and a tubular portion 6b. Between the groove portion 8e (second locking portion) formed in the support portion 8b of the casing shoe 8 and the groove portion 6d (first locking portion) and the groove portion 8e (second locking portion). It is comprised from the connecting member 10 which does. In the present embodiment, as the connecting member 10, an iron wire 10 a that is finally connected by welding to form a ring shape as shown in FIG. 14 is used.

  The connecting procedure of the ring bit 6 and the casing shoe 8 in the connecting structure J is as follows. First, the cylindrical portion 6b of the ring bit 6 is inserted into the buffer member 11 and placed on the end surface 6e. Next, the cylindrical portion 6b of the ring bit 6 is inserted into the support portion 8b of the casing shoe 8, and the concave groove portion 6d formed on the outer peripheral surface of the cylindrical portion 6b and the support portion 8b of the casing shoe 8 are inserted. The vertical position (axial position) with the provided groove 8e is matched. Thereafter, the wire 10a is inserted into the through hole 8f from the outside of the casing shoe 8, and the wire 10a is mounted between the concave groove portions 8e and 6d. Here, as described above, the through hole 8f is formed so as to guide the inserted wire 10a in the tangential direction of the two groove portions 6d and 8e having a ring shape, and therefore, between the both groove portions 6d and 8e. The wire 10a can be easily attached. Finally, both ends P (see FIG. 14) of the attached wire 10a are welded through the through-hole 8f, and further, a metal piece is embedded in the through-hole 8f to be closed by welding. And if the upper end part of the casing shoe 8 which attached this ring bit 6 is joined to the lower end part of the casing 7 which stood up substantially perpendicularly by welding W, the said connection structure J will be completed. FIG. 12 shows a state after the connection structure J is attached to the pilot bit 5. Before the pilot bit 5 is attached, the ring bit 6 is slightly lowered as shown in FIG. 10 is in contact with the upper end portion of the groove portion 6d and the lower end portion of the groove portion 8e, but does not come off.

  The dimensional relationship of each part in the connection structure J is as follows. That is, as shown in FIG. 12, the inner diameter of the inner peripheral surface 8d of the support portion 8b of the casing shoe 8 is designed to be larger than the outer diameter of the cylindrical portion 6b and smaller than the outer diameter D10 (see FIG. 14) of the wire 10a. The outer diameter of the cylindrical portion 6b is designed to be larger than the inner diameter d10 (see FIG. 14) of the wire 10a. Further, the width H (vertical dimension in FIG. 12) of the grooves 6d and 8e is designed to be approximately 150% of the height (thickness, diameter) α of the wire 10a itself as the connecting member 10.

  In the connecting structure J having the above-described configuration, a gap is formed between the ring bit 6 and the casing shoe 8 to enable relative rotational movement and vertical movement. In addition, the wire 10a is placed in both the grooves 6d and 8e. , Even if the ring bit 6 and the casing shoe 8 move relative to each other in a predetermined range in the vertical direction (axial direction), as shown in FIG. 13, the grooves 6d and 8e and the wire 10a interfere with each other. Thus, the ring bit 6 and the casing shoe 8 are structured not to be detached in the vertical direction (axial direction). Further, since the width H (vertical dimension in FIG. 12) of the groove portions 6d and 8e is larger than the height (thickness) α of the wire 10a itself, it is easier to attach the wire 10a to the groove portions 6d and 8e. It has become.

  According to the connecting structure J, the ring bit 6 and the casing shoe 8 that are relatively moved (relative rotation and axial movement) can be firmly and reliably connected with each other while being a simple and inexpensive structure. Further, it is possible to provide a connecting structure that can be easily assembled without reducing the strength and rigidity of the ring bit 6 and the casing shoe 8.

  Further, according to the connecting structure J, the connecting member 10 is provided between the groove 6 d as the first locking portion formed in the ring bit 6 and the groove 8 e as the second locking portion formed in the casing shoe 8. Therefore, it is not necessary that the first locking portion and the second locking portion are in direct contact with each other, and the workability of the ring bit 6 and the casing shoe 8 can be reduced. While the strength and rigidity can be improved, a structure that enables a strong and reliable connection can be easily realized while being a simple and inexpensive structure through the wire 10a as the connecting member 10.

  Further, according to the connecting structure J, even if the vertical dimension of the ring bit 6 is extended to provide the connecting structure J, the extended portion is located inside the casing shoe 8, so that it is rotated. However, the rotational resistance does not increase during excavation. Therefore, according to the connection structure J, a connection structure that can make a strong and reliable connection while being relatively movable within a predetermined range, and a structure in which resistance during excavation caused by rotating contact with the ground is kept low. It is structurally possible and easy to achieve both.

  Further, according to the connecting structure J, the outer peripheral surface of the casing shoe 8 in which the connecting structure J is arranged is in contact with the soil, so that the pilot bit 5 (and the screw rod 3) accommodated therein is attached. It is structurally possible and easy to provide the protrusion 8g on the outer peripheral surface for preventing the casing shoe 8 (and the casing 7 joined thereto) from rotating together. Further, according to the articulated structure J, the vertical dimension of the casing shoe 8 can be freely set, so that the vertical dimension of the protrusion 8g can be extended over a wide range, and therefore, the joint rotation can be more effectively prevented. And easy.

  Returning to FIGS. 1 and 2, the earth auger 2, screw rod 3, down-the-hole hammer 4 in parallel with the construction of the device fixing frame 9, the standing of the casing 7, and the mounting work of the casing shoe 8 to the casing 7. And the pilot bit 5 are assembled into a predetermined shape as shown in FIG. Specifically, the earth auger 2 is arranged at the top, one end of the screw rod 3 is connected to the output shaft 2b of the earth auger 2, and the down-the-hole hammer 4 is connected to the other end of the screw rod 3. Further, below the down-the-hole hammer 4, the drive shaft portion 5a of the pilot bit 5 is attached so as to be capable of relative movement in the vertical direction (axial direction) and transmission of rotation by, for example, spline fitting. As a result, the earth auger 2 is disposed at the top, the screw rod 3 and the down-the-hole hammer 4 are connected to the lower side, and the assembly in which the pilot bit 5 is attached to the lower side is assembled.

  Then, the assembly is inserted into the standing casing 7 while being suspended by a crane. At this time, the earth auger 2 is inserted with the pilot bit 5 facing down, and the pilot bit 5 is connected to the ring bit 6 by the method described below. Thereby, as shown in FIG. 2, the excavator 1 is assembled.

  In the excavator 1 shown in FIG. 2, the earth auger 2 located at the upper end portion of the assembly is connected to the upper end portion of the casing 7. At this time, to prevent the equipment frame 2b of the earth auger 2 from rotating together with the rotation of the electric motor housed therein, as shown in FIGS. And is connected to the upper end portion of the casing 7. The anti-rotation cap 20 has a cap body 20a made of a hollow cylindrical member that is closed at the top and opened at the bottom. The lower end of the equipment frame 2b of the earth auger 2 is fixed by welding or the like at the top. A plurality of cap-side rotation engagement plates 20b projecting inward toward the central axis on the surface are provided at substantially equal intervals along the circumferential direction. On the other hand, on the outer peripheral surface of the upper end portion of the casing 7, a casing-side rotation engagement plate 7b protruding outward from the central axis as a portion for engaging with the cap-side rotation engagement plate 20b is substantially along the circumferential direction. A plurality are provided at equal intervals. And the cap main body 20a which comprises this rotation stop cap is externally fitted so that the outer side of the upper end part of the casing 7 may be covered from the opening part provided in the lower end side of the said cap main body 20a. It has a structure to be mounted.

  Further, in the excavator 1 shown in FIG. 2, the pilot bit 5 located at the lower end of the assembly is attached to the ring bit 6 attached below the casing 7 through the casing shoe 8 using a bayonet mount. Removably connected (chucked). The bayonet mount structure will be described in detail. On the outer peripheral surface of the pilot bit 5, as described above, the notch portion 5g for locking has a predetermined range, that is, a discharge groove 5e at regular intervals of approximately 60 degrees around the circumference. For example, six locations are provided in a range rotated by 20 degrees in a direction opposite to the rotation direction of the electric motor (a counterclockwise direction in a plan view in FIG. 5) at the starting point. As described above, six locking projections 6f are provided in a predetermined range at equal intervals of approximately 60 degrees around the circumference (see FIGS. 5 to 8).

  The connection procedure using the bayonet mount structure having the above-described configuration is as follows. First, the locking projection 6f of the ring bit 6 and the discharge groove 5e provided in the pilot bit 5 are aligned so as to overlap in plan view (the positions are located between the locking notch 5g and the locking projection 6f). Is the angular position where the non-fitted state.) In this state, both or one of them is moved in the axial direction so that the locking projection 6f of the ring bit 6 and the locking notch 5g of the pilot bit 5 have the same height in a side view. Thereafter, with the pilot bit 5 being stationary, the ring bit 6 is rotated in a predetermined direction in which the locking notch 5g extends (in FIG. 5, it is counterclockwise in plan view. The rotation direction is opposite to the rotation direction of the electric motor. (For example, when the pilot bit 5 is rotated while the ring bit 6 is stationary, the pilot bit 5 is rotated clockwise by 20 degrees in plan view). As a result, the protrusion 6f of the ring bit 6 and the locking notch 5g of the pilot bit 5 are brought into a fitted state. In order to release the fitting state, the ring bit 6 is reverse to the predetermined direction so that the locking projection 6f of the ring bit 6 is positioned at the discharge groove 5e of the pilot bit 5 in plan view. For example, the pilot bit 5 may be rotated clockwise by 20 degrees (or the pilot bit 5 may be rotated counterclockwise by 20 degrees, for example). Thereby, the assembly work of the excavator 1 is completed.

  After the assembly work of the excavator 1, the electric motor included in the earth auger 2 is started in a state where the excavator 1 is aligned with the pile core to start the drilling work. The rotational driving force of the electric motor is transmitted to the pilot bit 5 and the ring bit 6 connected to the pilot bit 5 through the screw rod 3 connected to the output shaft 2c, and the center side drill piece 5c and the ring bit provided in the pilot bit 5 are provided. The ground is excavated by the outer peripheral drill piece 6 c included in 6. The excavated soil is pushed upward through the discharge groove 5e together with the pressurized air fed through the air passage 5d, and is carried to the surface of the earth by being screwed on the screw portion 3b included in the screw rod 3.

  Simultaneously with the excavation, a pressing force (driving force) from the down-the-hole hammer 4 is applied to the upper end surface 5f of the shoulder portion 5h formed above the head portion 5b of the pilot bit 5 at a cycle of, for example, 3 times per second. This pressing force (driving force) is transmitted to the upper end surface 8c of the casing shoe 8 opposed thereto through the lower end surface 5i of the shoulder 5h, and further applied to the casing 7 joined to the casing shoe 8. As a result, the casing 7 and the casing shoe 8 are efficiently driven downward into the hole formed by excavation of the pilot bit 5 and the ring bit 6. The drilling operation is advanced by a series of these operations.

  In the excavator 1 according to the present invention, the force for driving the casing 7 and the casing shoe 8 downward can be transmitted also through the connecting structure J. That is, the pressing force (driving force) from the down-the-hole hammer 4 is transmitted to the ring bit 6 connected by the bayonet mine through the pilot bit 5, and then the casing shoe 8 and the casing joined thereto through the connecting structure J. 7 is transmitted. The transmission of force through the articulated structure J wears on the shoulder 5h (more specifically, the lower end surface 5i of the shoulder 5h) of the pilot bit 5 that is collected after the work is completed and reused repeatedly. However, this is particularly important when the transmission path through the portion fails to function sufficiently. According to the connection structure J that enables strong connection without reducing the strength and rigidity of the ring bit 5 and the casing shoe 8, the function of transmitting the force can be surely achieved.

  In order to proceed the drilling operation smoothly and efficiently, it is essential to quickly discharge the excavated soil, and for that purpose, the pressing force of the pressurized air effectively acts on the waste soil, and the added Although it is desirable that the waste soil is efficiently pushed up by riding on the compressed air, in order to make this possible, the casing 7 is brought together with the pilot bit 5 and the ring bit 6 as rotating elements accommodated therein. And a structure that does not rotate. Here, the connecting structure J of the present invention is configured such that the cylindrical portion 6b of the ring bit 6 that is a rotating component is disposed on the inside, and the support portion 8b of the casing shoe 8 that is a non-rotating component is disposed on the outside. Yes. For this reason, the connecting structure J has a structural feature such that a sufficiently long protrusion 8g can be easily provided on the outer peripheral surface of the support portion 8b of the casing shoe 8. Providing the protrusion 8g having a predetermined length increases the contact resistance between the casing shoe 8 and the ground, particularly the contact resistance acting in a direction to prevent the casing shoe 8 from rotating. The casing 7 joined thereto can be effectively prevented from rotating together with the pilot bit 6 and the ring bit 5 as rotating elements accommodated therein. As described above, this effect is due to the structural features of the connecting structure J (see paragraph “0053”).

  Unlike the present invention, in the case of an articulated structure in which the cylindrical portion 6b of the ring bit 6 which is a rotating part is arranged on the outside and the support portion 8b of the casing shoe 8 is inserted on the inside, the soil It is structurally difficult to provide the protrusion 8g in contact with the outer peripheral surface of the casing shoe 8 with a sufficient length. Therefore, it is only necessary to prevent the rotation of the casing shoe 8 and the casing 7 joined thereto together. It is difficult to generate sufficient contact resistance by the protrusion 8g.

  Further, the structure for preventing the rotation of the casing 7 by the protruding portion 8g has an advantage of excellent productivity because it is not necessary to directly process the casing 7 made of a relatively thin plate material. That is, in the rotation prevention means (second rotation prevention means) of the casing included in the invention described in Patent Document 1, the rotation engagement groove (12b) that engages with the rotation roller (22) is provided on the outer periphery of the casing (12). Although it is necessary to form on the surface, it is not easy to form the rotation engagement groove (12b) which requires a certain depth on the outer peripheral surface of the casing made of a thin plate material, and the productivity is remarkably deteriorated (substantially) However, in the excavator 1 according to the present embodiment, there is no need to directly process the casing 7 as described above, which causes such a problem. There is no.

  In the excavator 1 according to this embodiment, the gap between the lower end of the casing shoe 8 and the end face 6e of the ring bit 6 is filled (in other words, the end face 6e and the lower end are in contact with each other). The buffer member 11 is placed. As a result, the impact caused by the collision between the lower end of the casing shoe 8 and the end face 6e of the ring bit 6 caused by the strong pressing force (driving force) from the down-the-hole hammer 4 is absorbed, and noise and vibration during drilling work are effective. The effect of being suppressed is brought about.

  By the drilling operation, the casing 7 is erected so as to be embedded in the ground. When the drilling reaches a predetermined depth, the connection (chucking) between the pilot bit 5 and the ring bit 6 is released, and the pilot bit 5, the screw rod 3 and the down-the-hole hammer 4 are pulled out to collect these parts. On the other hand, the casing 7, the casing shoe 8, and the ring bit 6 are used as main piles while remaining in the ground.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims, the specification, and the drawings. Further, the embodiments can be combined with each other as long as there is no contradiction in the purpose, configuration, and the like. Moreover, even if the content shown by the said description and drawing is a part, each can become independent embodiment, and embodiment of this invention is the content shown by the said description and drawing. It is not limited to one embodiment combining the above.

  For example, instead of the groove portion 6d constituting the connection structure J, a ring-shaped step portion that is recessed on the lower side (that is, a state where there is no step portion on the lower side of the groove portion 6d), and a ring that is recessed on the upper side instead of the groove portion 8e. It is good also as a shape-shaped level | step-difference part (namely, the state without the level | step-difference part upper side of the groove part 8e). In short, the first and second engaging portions may have any configuration as long as the connecting members inserted therebetween can be connected to each other so as to be relatively movable.

1: Excavator 2: Earth auger 3: Screw rod 4: Down the hole hammer 5: Pilot bit 5a: Drive shaft portion 5b: Head portion 6: Ring bit 6a: Head portion 6b: Cylindrical portion 6d: Groove portion (first locking) Part)
7: Casing 8: Casing shoe 8a: Main body base portion 8b: Support portion 8d: Inner peripheral surface 8e: Groove portion (second locking portion)
8f: Through hole (wire insertion hole)
8g: Projection 9: Device fixing frame 10: Connection member 10a: Wire 11: Buffer member J: Connection structure

Claims (2)

A casing made of a circular pipe member extending vertically;
A casing shoe made of a cylindrical member coaxially joined to the lower end of the casing;
A pilot bit rotatably inserted into the casing and the casing shoe;
In a drilling rig comprising a ring bit that is detachably attached to a lower end outer peripheral portion of the pilot bit via a joint element,
The ring bit has a cylindrical portion that is inserted into the casing shoe and has a first locking portion formed on the outer peripheral surface thereof.
The casing shoe has an inner peripheral surface on which a second locking portion is formed facing the outer peripheral surface of the cylindrical portion of the ring bit and facing the first locking portion,
The ring bit and the casing shoe are connected to each other via a connecting member that is inserted between the first locking portion and the second locking portion and interferes with the two locking portions. and,
Further, the connecting member is made of an annular wire, and is formed to have a size such that an inner peripheral side thereof is accommodated in the first locking portion and an outer peripheral side thereof is accommodated in the second locking portion. And drilling rig. A method for assembling an excavator according to claim 1 ,
A wire insertion hole extending from the outer peripheral surface to the second locking portion is opened in the casing shoe, the wire is inserted into the wire insertion hole from the outside of the casing shoe, and the wire is connected to the first engagement member. A method for assembling an excavator, wherein the excavator is mounted between a stop portion and the second locking portion.

Images