JP3772591B2 - Casing pipe connection structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a casing pipe connection structure for connecting a plurality of cylindrical casing pipes in an axial direction in a drilling hole excavated by an excavation tool in excavation of an AGF method or a pile. is there.
[0002]
[Prior art]
When excavating a soft or medium hard rock layer with an excavating tool, in order to prevent the surrounding ground from collapsing into the excavated drill hole and filling the drill hole, A cylindrical casing pipe is inserted into the drilling hole, and when the drilling hole is deeper than the length of a single casing pipe, each time the previous casing pipe is inserted into the drilling hole, The next casing pipe is sequentially connected in the axial direction. And when connecting a plurality of casing pipes in the axial direction in this way, conventionally, the connecting end of the next casing pipe is butted against the connecting end of the rear end of the previously inserted casing pipe, or Both connecting ends can be welded after fitting, or the connecting end of one casing pipe can be inserted into the connecting end of the other casing pipe, and the connecting ends of these connecting ends are opposed to each other. These casings are connected by forming male and female screw portions on the peripheral surface and screwing both connecting end portions.
[0003]
[Problems to be solved by the invention]
However, in the former connection structure by welding, it is necessary to prepare equipment for welding at the drilling site of the drilling hole, and much time is spent on the welding work for connection. Is inevitable. Further, when excavation is performed while inserting the casing pipe into the drilling hole as described above, the casing pipe may be pulled out after the drilling hole is formed to a predetermined depth. In order to sequentially remove the pipes, the welded connection ends must be heated again and blown, resulting in the required equipment and a lot of work time. Furthermore, the welded and melted casing pipe is often melted at its connecting end or altered by heat, and in this state it cannot be used for insertion into the drilling hole again. There is also a problem that it cannot be done.
[0004]
On the other hand, the latter connection structure by screwing does not cause such a problem as the connection structure by welding, but on the other hand, when inserting the casing pipe into the drilling hole during excavation, especially when cutting. If the male and female screw portions are loosened due to vibrations or the like when being pulled out from the hole, the previously inserted casing pipe may fall off and be left in the hole. However, when such a casing pipe falls off, it takes a lot of labor and time to take out the casing pipe from the drilling hole, resulting in a significant loss of work efficiency of excavation work. Further, if the male and female screw portions are firmly screwed and connected so that such loosening does not occur, much labor is required to remove the casing pipe due to the biting of the male and female screw portions.
[0005]
The present invention has been made in view of such circumstances, and can be easily connected and detached without requiring welding equipment and the like, and can be reused as it is after being removed, while being inserted into a drilling hole. It aims at providing the connection structure of the casing pipe which does not drop out at the time of drawing.
[0006]
[Means for Solving the Problems]
In order to solve the above problems and achieve such an object, the present invention is a casing pipe connection structure for connecting a cylindrical casing pipe inserted into a drilling hole in the axial direction thereof. Te, the inner circumference of the connecting end of the pair of the connecting end portion of the casing pipe to be connected to each other, connecting ends formed at a rear end portion of one of the casing pipe is formed at the tip portion of the other casing pipe insertable and to, the connecting end of one of the casing pipe above, to form a male screw portion on an outer peripheral portion of the front end side, on the rear end side of the male screw portion, coupling extending toward the axial direction a slit that reaches the rear end, the connecting end of the other of the casing pipe to form the internal thread portion of the male screw portion screwed into the inner peripheral portion of the distal end side, the slits Formed part Above the outer peripheral surface among mutually opposing with each other connection end, characterized in that the formation of the engageable and has been engaging recess and the engaging projection in the axial direction in.
[0007]
Therefore, according to such a casing pipe connection structure, the male screws are aligned with each other so that the connection end of the one casing pipe is inserted into the inner periphery of the connection end of the other casing pipe. When the female thread portion is screwed into the portion, the connecting end portion of the one casing pipe in which the slit is formed is elastically deformed in the radial direction with respect to the axis by the slit, thereby forming the engagement recess. The connecting end portion climbs over the engaging convex portion, the engaging concave and convex portions engage in the axial direction, and the casing pipes are connected. Conversely, if the pair of casing pipes are forcibly rotated relative to each other in the direction in which the male screw portion and the female screw portion are loosened, the connecting end portion of one casing pipe can be pulled out from the other casing pipe. Contrary to the above case, the connecting end portion of one casing pipe is elastically deformed again to reduce its diameter so that the engaging concave portion gets over the engaging convex portion, and the engaging concave and convex portions are disengaged. The casing pipes can be removed .
In this way, the connection end portions of one casing pipe are screwed and inserted into the connection end portion of the other casing pipe so that both connection end portions are engaged and connected in the axial direction. Thus, no welding equipment is required, and the casing pipes can be easily connected. Even if the male and female screw portions that are easy to loosen are employed, the male and female screw portions are loosened due to vibrations caused by the rotary hitting of the excavating tool as in the case of the conventional connection only by screwing, and the casing pipe is The casing pipe can be inserted into the drilling hole while being securely connected without being detached or dropped off in the drilling hole.
[0008]
Here, in this way the slit is formed in the connecting end of one of the casing pipe above, in the portion where the slit is formed in the other of the casing pipe wall thickness of the connecting end portion of one of the casing pipe above It is desirable to make it smaller than the thickness of the connecting end, and this makes it possible to elastically deform the connecting end of the one casing pipe in which the slit is formed.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
1 to 6 show an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an excavation tool according to the present embodiment. A drilling device such as a drifter (not shown) is connected via the coupling 2 and the coupling 3, and the excavation tool is driven by the rotational force around the axis O and the striking force toward the front end in the direction of the axis O. 1 advances while excavating a rock layer by the excavation bit 4 provided in the front-end | tip part, and forms a drilling hole. An annular casing top 5 is fitted on the outer periphery of the excavating tool 1 so as to be engageable with the excavating tool 1 toward the front end side in the axis O direction. The pipe 6 is joined, and only the striking force is given through the casing top 5 as the tool body 1 advances, whereby the casing pipe 6 is inserted into the drilling hole.
[0010]
And the connection end part 7 is formed in the rear-end part of this state-of-the-art casing pipe 6, and when this casing pipe 6 is inserted to the predetermined depth, the connection end part 8 will be in the tip part at the rear end. The formed next casing pipe 6 is connected and inserted into the drilling hole, and by repeating such an operation in sequence, a plurality of drilling holes having a depth greater than the length of the single casing pipe 6 are provided. Casing pipes 6 are inserted. That is, the connecting end portion 7 is formed at the rear end portion of each casing pipe 6... And the tip end portion of the casing pipe 6 except the most advanced casing pipe 6 joined to the casing top 5. A connecting end portion 8 is formed, and the plurality of casing pipes 6 are sequentially connected by the connecting end portions 7 and 8 with the insertion into the drilling hole as described above.
[0011]
Of the pair of casing pipes 6 and 6 connected in this manner, the connecting end portion 7 formed at the rear end portion of one casing pipe 6 on the front end side (hole bottom side of the drilling hole) is as shown in FIG. As shown in FIG. 3, the outer diameter is formed to be reduced by one step. In the present embodiment, a male screw portion 9 is formed on the outer periphery of the tip side (left side in FIG. 2). On the other hand, the connecting end portion 8 formed at the front end portion of the other casing pipe 6 on the rear end side of the pair of casing pipes 6 and 6 has an inner diameter that is increased by one step as shown in FIG. In the inner periphery of the tip end side (left side in FIG. 4), a female screw portion 10 that is screwed into the male screw portion 9 is formed. Has been. The casing pipes 6 and 6 connected to each other have the same inner and outer diameters except for the connecting end portions 7 and 8, and the inner diameter of the connecting end portion 7 is equal to the inner diameter of the casing pipe 6. The outer diameter of the connecting end 8 is formed to be equal to the outer diameter of the casing pipe 6.
[0012]
Here, in this embodiment, these male and female screw portions 9 and 10 are not a general triangular screw or a rope screw or a high lead screw used for this type of mining tool, but the axis O as shown in FIG. And the shape of the threads 9A, 10A in the cross section including the trapezoidal shape, and the inclination angle θ of the threads 9A, 10A with respect to the axis O of the slopes 9B, 10B is set in the range of 40 ° to 70 °, The lead angle is set in the range of 5 ° to 16 °. However, according to such male and female screw parts 9, 10, the lead angle is large, the slopes 9B, 10B of the threads 9A, 10A are large, and the cross sections of the threads 9A, 10A are trapezoidal. Therefore, the contact area of the male and female screw portions 9 and 10 can be reduced, and the male and female screw portions 9 and 10 can be prevented from being tightened excessively.
[0013]
Then, the connecting end 7 of the one casing pipe 6 on the front end side penetrates the connecting end 7 in the radial direction with respect to the axis O on the rear end side (right side in FIG. 2) of the male screw portion 9. In addition, a plurality of (six in this embodiment) slits 11 extending in parallel with the axis O and reaching the rear end of the connecting end 7 are formed at equal intervals in the circumferential direction, and the slits 11 are formed. On the outer peripheral surface of the connecting end 7 in the portion, a concave groove having a “U” shape whose cross section opens toward the outer peripheral side is configured to circulate around the axis O as the engaging concave portion 12 in the present embodiment. Is formed. A tapered surface 13 that gradually decreases in diameter toward the rear end side is formed on the outer peripheral surface of the connecting end portion 7 at a portion further on the rear end side than the engagement recess 12. The outer diameter of the portion where the slits 11 are formed is slightly smaller than the inner diameter of the male screw portion 9.
[0014]
On the other hand, at the connecting end portion 8 of the other casing pipe 6, a protrusion that protrudes one step toward the inner peripheral side on the rear end side of the female screw portion 10 is used as the engaging protrusion 14 in the present embodiment. It is formed so as to circulate around the axis O. The engagement convex portion 14 has a shape in a cross section including the axis O. The surface 14A facing the front end side is a tapered surface that gradually decreases in diameter toward the rear end side, and the surface 14B faces the inner peripheral side. Is formed in a trapezoidal shape in which the surface 14C facing the rear end side is perpendicular to the axis O, and the diameter of the surface 14B facing the inner peripheral side is the engagement recess 12 It is set as the magnitude | size which can be fitted in the surface 12A which faces the outer peripheral side. Further, the width in the direction of the axis O of the concave portion 15 defined in the connecting end portion 8 on the rear end side with respect to the engaging convex portion 14 is such that the engaging concave portion 12 of the connecting end portion 7 where the tapered surface 13 is formed. The thickness t ₈ of the connecting end 8 in the recess 15 is slightly larger than the width of the portion on the rear end side in the direction of the axis O, and the connecting end 7 in the portion where the slit 11 is formed. It is formed to be larger than the thickness t _7.
[0015]
In order to connect the other casing pipe 6 to the rear end of one casing pipe 6 on the front end side by the connecting end portions 7 and 8 formed in this way, the connecting end portion 7 of the one casing pipe 6 is rearward. What is necessary is just to screw in the internal thread part 10 in the said external thread part 9, aligning the axis line O so that it may be inserted in the connection end part 8 of the other casing pipe 6 of the end side. However, when the connecting end 7 is inserted into the connecting end 8 in this way, the tapered surface 13 on the rear end side of the connecting end 7 is engaged with the engagement convex portion 14 on the rear end side of the connecting end 8. As a result, the portion of the connecting end 7 where the slit 11 is formed is elastically deformed to reduce its diameter. And when the said taper surface 13 got over the engaging convex part 14, while the part in which the slit 11 of the connection end part 7 was diameter-expanded and it returns to an original state, an engaging convex part is set to the engaging recessed part 12. 14 is fitted and engaged in the direction of the axis O, and the casing pipes 6 and 6 are connected via these connecting ends 7 and 8 as shown in FIG.
[0016]
Thus, according to the connection structure of the casing pipes 6 and 6 by the connection end portions 7 and 8 having the above-described configuration, the connection end portions 7 and 6 are simply inserted into the connection end portion 8 by screwing. Since 8 is engaged and connected in the direction of the axis O, welding equipment is not required as in the case of connection by welding, and the casing pipes 6 and 6 can be easily connected. On the other hand, even if the male and female screw portions 9 and 10 that are easy to loosen are employed as in the present embodiment, this may be caused by vibrations associated with the rotary hitting of the excavating tool 1 as in the case of connection by conventional screwing alone. The male and female screw portions 9 and 10 are not loosened and the casing pipes 6 and 6 are not detached or dropped out in the drilling hole, and the casing pipes 6 are inserted into the drilling hole while being securely connected. It becomes possible.
[0017]
Further, if the pair of casing pipes 6 and 6 are forcibly rotated relative to each other in the direction in which the male and female screw portions 9 and 10 are loosened, the connecting end portion 7 can be pulled out from the connecting end portion 8. On the contrary, the connecting end 7 is elastically deformed again to reduce the diameter so that the engagement recess 12 gets over the engagement protrusion 14, and the engagement between the engagement recess 12 and the engagement protrusion 14 is released. Therefore, the male and female screw portions 9 and 10 can be loosened and the casing pipes 6 and 6 can be removed. However, the connection ends 7 and 8 of the casing pipes 6 and 6 thus removed can be reused as they are because the elastically deformed portions only return to their original state, which is economical.
[0018]
On the other hand, in the present embodiment, the slits 11 are formed in the connecting end portion 7 of one casing pipe 6 on the front end side that is inserted into the inner periphery of the connecting end portion 8 of the other casing pipe 6 on the rear end side. That is, the slits 11 are not exposed to the outer peripheral side of the casing pipes 6 and 6 in a state in which the connecting end portions 7 and 8 are connected. For this reason, when the casing pipes 6 and 6 connected by the connecting end portions 7 and 8 are inserted into the drilling holes, earth and sand are bitten into the slits 11 from the inner walls of the drilling holes. When the casing pipes 6 and 6 are pulled out and removed from the drilling holes after excavation is completed, the elastic deformation of the connecting end 7 is hindered by the biting of the earth and sand into the slits 11 and removed. It is possible to prevent a situation that hinders the situation.
[0019]
Furthermore, in the present embodiment, the engagement convex portions 14 are formed so that the thickness of the connection end portions 7 and _{8 is} larger than the thickness t ₇ of the connection end portion 7 in the portion where the slits 11 are formed. The thickness t ₈ of the recess 15 of the connecting end 8 is larger, in other words, in the portion where the slits 11 are formed, the thickness t _{7 of the} connecting end 7 where the slits 11 are formed. However, it is set to be smaller than the wall thickness t ₈ of the connecting end 8 where the slits 11 are not formed. Therefore, according to this embodiment, when the casing pipes 6 and 6 are connected by the connecting end portions 7 and 8, the connecting end portion 7 is reliably elastically deformed at the portion where the slits 11 are formed. The diameter can be reduced, and the engagement concave portion 12 and the engagement convex portion 14 can be engaged and disengaged more smoothly.
[0020]
On the other hand, in this embodiment, in addition to the engagement between the engagement concave portion 12 and the engagement convex portion 14, the connection end portions 7 and 8 are also connected by the male and female screw portions 9 and 10. In addition to this, as described above, the thickness t ₈ in the concave portion 15 of the connecting end ₈ is made larger than the thickness t ₇ in the portion where the slits 11 of the connecting end 7 are formed. For this reason, in the unlikely event that an excessive load acts on the connecting end portions 7 and 8, the thickness t ₇ is small, and the portion of the connecting end portion 7 where the slits 11 are formed is damaged. However, since the connected state of the casing pipes 6 and 6 is maintained by the male and female screw portions 9 and 10 screwed with the concave portion 15 of the connecting end portion ₈ having a large wall thickness t ₈ , these casing pipes are instantly used. It is possible to avoid a situation where 6 and 6 come off and fall off.
[0021]
In this embodiment, in addition to the engagement between the engagement recess 12 and the engagement protrusion 14 as described above, the male and female screw portions 9 and 10 are formed on the inner and outer peripheral surfaces of the connecting end portions 7 and 8 and screwed together. Although is, on the opposite side of the engaging concave-convex portions 12, 14 across the male and female threaded portions 9 and 10 in the direction of the axis O in the continuous Yuitan section 7,8, other engagement uneven part engaged with each other May be formed. Further, in the present embodiment, of the pair of casing pipes 6 and 6 connected to each other, the connecting end portion 7 formed at the rear end portion of the one casing pipe 6 on the front end side is replaced with the other end on the rear end side. It can be inserted into a connecting end 8 formed on the front end side of the casing pipe 6, a slit 11 is formed in the connecting end 7 and an engaging recess 12 is formed, and the connecting end 8 is engaged. Convex portions 14 are formed, but conversely, the connecting end of the casing pipe on the rear end side can be inserted into the connecting end of the casing pipe on the front end side, or the connecting end on the inner peripheral side engaging projections on part outer periphery may be provided with engagement recesses to the connecting end portion of the outer peripheral side circumferential provided with a.
[0022]
【The invention's effect】
As described above, according to the present invention, it is possible to reliably and easily connect the casing pipe inserted into the drilling hole and remove the casing pipe pulled out from the drilling hole. In this case, the casing pipe can be prevented from falling off, and the casing pipe pulled out and removed from the hole can be reused as it is for insertion into another hole.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of the present invention.
2 is a side sectional view showing a connecting end portion 7 of one casing pipe 6 on the front end side in the embodiment shown in FIG.
3 is a view in the direction of arrow X in FIG. 2;
4 is a side sectional view showing a connecting end 8 of the other casing pipe 6 on the rear end side in the embodiment shown in FIG.
FIG. 5 is an enlarged cross-sectional view including the axis O of the male and female threaded portions 9 and 10 of the coupling end portions 7 and 8 of the embodiment shown in FIG.
6 is a side sectional view showing a state in which connecting end portions 7 and 8 are connected in the embodiment shown in FIG. 1;
[Explanation of symbols]
1 excavation tool 6 the casing pipe 7 and 8 connecting end 9 male threaded portion 10 internally threaded portion 11 slit 12 engaging recess 14 engaging projection O casing pipe 6 ... center axis t ₇ slit 11 ... connection end in the formed part is Thickness t ₈ of the portion 7 Thickness of the connecting end portion 8 corresponding to the portion where the slits 11 of the connecting end portion 7 are formed.

Claims (2)

A casing pipe connection structure for connecting a cylindrical casing pipe inserted into a drilling hole in an axial direction thereof, wherein the connection end portions of the pair of casing pipes connected to each other are connected to one casing pipe. The connecting end formed at the rear end can be inserted into the inner periphery of the connecting end formed at the tip of the other casing pipe. portion with a male screw portion is formed on the outer periphery of the rear end side of the male screw portion, the slit is reached the rear end of the connection end portion extending toward the axial direction is formed, the other casing pipe the connecting end portion, the outer peripheral surface among the female screw portion to be screwed with the inner periphery to the external thread of the portion of the tip side is formed, facing each other of the connecting end portions in the portion where the slit is formed The connection structure of the casing pipe, characterized in that the engaging recess and the engaging projection which is engageable in the axial direction is formed. The thickness of the connecting end of the one casing pipe is smaller than the thickness of the connecting end of the other casing pipe in the portion where the slit is formed. Casing pipe connection structure.

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