JPH1143938A - Steel pipe pile connection part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means to connect an upper and a lower steel pipe piles to each other in a short time without deteriorating strength at connection parts of the steel pipe piles provided with a connection screw part where a female screw part threaded at one end part of one steel pipe pile to be vertically connected is connected to a male screw part threaded at the other end part of the other steel pipe pile by engaging them with each other. SOLUTION: A connection screw part 4 is formed of multi-groove parallel threads. As a more favorable mode, a flank angle on the tip part side of a male screw part 6 is set to be larger than a flank angle on the base end side of the male screw part 6, a screw surface of a female screw part 5 is formed along a screw surface of the male screw part 6, a stepped part 1b is provided between the male screw part 6 and an outer circumferential part 1a of a steel pipe pile 1, a thread diameter of the male screw part 6 is formed to be smaller than an outer diameter of the steel pipe pile 1, and the stepped part 1b is composed as an abutment surface 7 to which an end surface 1c of the female screw part 5 can be abutted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting portion of a steel pipe pile, and more particularly, to a female screw portion screwed at one end of one steel pipe pile connected vertically and another end of the other steel pipe pile. The present invention relates to a connecting portion of a steel pipe pile provided with a connecting screw portion for screwing and connecting a male screw portion screwed to the steel pipe pile.

[0002]

2. Description of the Related Art Conventionally, in a connection portion of a steel pipe pile, FIG.
As shown in FIG. 1, one end side connecting portion 8 provided with a female screw portion 5 in which a single angle parallel female screw is screwed into a connecting screw portion 4 at the other end located above the lower steel pipe pile 1 to be built in the ground. And a single thread angle parallel male screw is screwed into the connection screw part 4 at the other end located below the upper steel pipe pile 1 to be connected to the lower steel pipe pile 1 that has been erected. A lower end side connecting portion 9 including a portion 6 is formed, and the upper steel pipe pile 1 is suspended from above the lower steel pipe pile 1 and rotated around an axis. The upper and lower steel pipe piles 1 are connected by screwing the portions 6 together.

[0003]

In the connection portion of the conventional steel pipe pile, since the connection screw portion 4 is formed by parallel screws, the connection portion 4 swings back and forth and right and left when it is lowered. It is difficult to align the steel pipe piles 1 connected from above with the axis of the steel pipe piles 1 below, and the amount of manual work for alignment is large, and there is a problem in work safety. There is a problem that the number of rotations of rotating the upper steel pipe pile 1 around the axis increases, thereby impairing work efficiency. The above-mentioned steel pipe piles are mainly used for prevention of landslide, and an earth pressure acts on the steel pipe piles that are connected and built, and an external bending force is exerted on the steel pipe piles after the casting. Regarding the conventional connection screw portion 4 described above,
This bending external force sufficiently presses the distal end portion 8b of the one end side connection portion 8 against the base end portion 9a of the male screw portion 6 of the other end side connection portion 9 when the connection screw portion 4 is connected. If not connected, with respect to one end side connection portion 8 of the lower steel pipe pile 1,
Since the male screw portion 6 formed on the other end side connection portion 9 of the upper steel pipe pile 1 is fitted into the female screw portion 5 of the one end side connection portion 8, from the inner side of the one end side connection portion 8. A bending force is exerted on the female screw portion 5. As a result, the distal end portion 8b of the one end side connecting portion 8 is deformed so as to expand. This is because there is a gap between the crest of the female screw portion 5 and the trough of the male screw portion 6 and a crevice between the crest of the male screw portion 6 and the trough of the female screw portion 5. This is because a relative deviation between the female screw portion 5 and the male screw portion 6 is allowed in the direction. Moreover, when an external bending force acts on the connected steel pipe pile, an axial compressive force acts on the inside (hereinafter, referred to as a compression side) of the bend, and the outside (hereinafter, referred to as a compression side).
Called the pull side. ) Is subjected to a tensile force in the axial direction. However, a reaction force against the tensile force is generated in the connecting screw portion between the male screw portion 6 and the female screw portion 5 in contact with each other. is there. The screw surface to be contacted is a screw surface on the base end side of the thread of each of the male screw portion 6 and the female screw portion 5, and the connected steel pipe piles 1 are separated from each other on the tension side. It will fit. This is facilitated by the reaction force against the surface pressure between the screw surfaces on the compression side. As a result, the screw surface of the female screw portion 5 is guided along the screw surface of the male screw portion 6 on the pulling side, and the distal end portion 8b is sufficiently pressed against the base end portion 9a to be connected. If not, the tension side of the female screw portion 5 is deformed in a direction away from the male screw portion 6. If the male screw portion 6 and the female screw portion 5 are separated from each other in this manner, the contribution to the bending strength on the pulling side cannot be expected.

As a means for solving the above-mentioned problem, as shown in FIG. 4, the connecting screw portion 4 is formed of a tapered screw, and the male screw portion 6 screwed to one end of one of the steel pipe piles 1 is provided at the base end thereof. It has been proposed that a shoulder portion 1b is provided so that an end surface 1c of a distal end portion of a female screw portion 5 screwed to the other end side of the other steel pipe pile 1 is brought into contact with the steel pipe pile 1 (Japanese Patent Laid-Open No. 7-8).
2738). However, in the connection screw portion 4 proposed above, if the end surface 1c abuts on the shoulder portion 1b with a sufficient surface pressure in a state where the taper screw is sufficiently tightened, it is possible to increase the bending strength. However, as long as the connection screw portion 4 is formed of a tapered screw, the tightening of the tapered screw is limited unless the processing accuracy of the tapered screw is extremely high. The end face 1c may not reach the shoulder 1b in some cases, or the tapered screw may not sufficiently engage even if the end face 1c contacts the shoulder 1b. If the screw is further tightened in a state where the screw is not sufficiently engaged, the screw thread may be crushed. If the end face 1c does not contact the shoulder 1b as in the former case, the same problem as that of the conventional connecting portion occurs, and the male screw portion 6 and the female screw portion 5 have both ends. Since the portion is formed thinner than the base end portion, it is inevitable that the resistance to deformation of the distal end portion of the female screw portion 5 as described above is reduced, and the female screw portion on the tension side as described above is inevitable. The deformation such that the tip of 5 is expanded is further promoted. Therefore, it is difficult to expect mechanical unification of the male screw part 6 and the female screw part 5 under the normal processing accuracy in the connection screw part 4, and it is difficult to reduce the bending strength. There is a problem that it is not easy to avoid. If the processing accuracy of the tapered screw is increased to such an extent that the male screw portion 6 and the female screw portion 5 can be mechanically integrated, the time and cost required for the thread cutting process become extremely high. Occurs.

Therefore, the connecting portion of the steel pipe pile of the present invention solves the above-mentioned problems, and provides means for connecting the upper and lower steel pipe piles in a short time without reducing the strength of the connecting portion of the steel pipe pile. The purpose is to:

[0006]

[Means for Solving the Problems]

[Characteristic configuration] A first characteristic configuration of the connecting portion of the steel pipe pile of the present invention for the above purpose is that the connecting screw portion is formed by a multi-parallel parallel screw. . According to a second characteristic configuration of the connecting portion of the steel pipe pile of the present invention, the flank angle of the distal end portion of the male screw portion in the first characteristic configuration is set at the base end of the male screw portion. The flank angle is larger than the flank angle of the female thread portion, and the screw surface of the female screw portion is formed along the screw surface of the male screw portion. As a third feature configuration, a step portion is provided between the male screw portion in the first feature configuration or the second feature configuration and an outer peripheral portion of the steel pipe pile, and The point is that the mountain diameter is formed smaller than the outer diameter of the steel pipe pile, and the step portion is formed as a contact surface to which the end face of the female screw portion can contact.

According to the first feature configuration, while maintaining a sufficient strength of the connecting portion,
The time required for screw connection can be reduced. That is, since the connecting screw portion is formed by the multi-threaded screw, the lead can be enlarged, and the required number of rotations of the steel pipe pile at the time of joining the pile can be reduced accordingly. Moreover, since the connecting screw portion is formed of parallel screws, even if the connecting screw portion is screwed with a sufficient screwing force, there is no change in the engagement of the screws. Since the screw surfaces of the connecting screw portions come into contact with each other with pressure, the connecting force in the axial direction of the steel pipe pile can be secured, and there is no risk of damaging the screw thread. It becomes possible to integrate and connect, and it becomes possible to provide bending strength. In addition, since the parallel screw is formed, the thickness of the connecting screw portion can be made constant from the base end side to the distal end side. Here, although it is a known means, it is extremely effective to form the connection screw portion so that the elastic section modulus and the plastic section coefficient are equal to or more than those of the steel pipe pile, and in a connected state, It is more effective to make it hold. In addition, the 2nd characteristic structure of the connection part of the steel pipe pile of this invention makes it easy to position the upper steel pipe pile with respect to the lower steel pipe pile without lowering the strength of the threaded joint. In other words, for a positional deviation within the range of the screw thread height, the screw surface that comes into contact when the upper steel pipe pile descends becomes the guide surface, but by increasing the flank angle of the screw surface that comes into contact, Since the guide surface having a large inclination can be formed, the screw surface to be brought into contact with the steel pipe pile is easily slipped when the upper steel pipe pile is lowered. Moreover, by making the flank angle of the opposite thread surface smaller than the flank angle of the abutting thread surface, it is possible to increase the cross-sectional area of the thread and maintain the strength of the threaded joint. Further, the external force acting on the steel pipe pile after being built is mainly a bending external force, but the acting force in the radial direction accompanying the external force is affected by the action of the screw surface having a larger flank angle. A large reaction force against force can be maintained. Also, for example, if the flank angle of the opposite thread surface is made relatively small while maintaining the cross-sectional area of the thread, the flank angle can be made smaller than that of the thread surface of a normal angled screw. The surface pressure of the screw surface on the opposite side where the flank angle is relatively reduced corresponds almost directly to the axial force, and the bending strength can be enhanced. Further, according to the third characteristic configuration of the connection portion of the steel pipe pile of the present invention, the bending strength of the connection portion of the steel pipe pile can be maintained without hindering the installation of the steel pipe pile after the joining pile. In other words, since the end surface of the female screw portion is provided with a contact surface that can be brought into contact with the female screw portion, a required surface pressure is applied to the end surface by tightening the connection screw portion formed of a parallel screw. As a result, the bending strength of the connecting screw portion can be enhanced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an embodiment of the connecting portion of the steel pipe pile according to the present invention will be described below with reference to the drawings. Note that the same elements as those described in the related art and elements having the same functions are denoted by the same reference numerals as those in FIGS. 3 and 4, and a part of the detailed description is omitted. .

FIG. 1 is an axial sectional view of a main part for explaining an example of connection of a connecting portion of a steel pipe pile according to the present invention. FIG. 1A shows a connecting portion before connection, and FIG. The connecting portion after connection is shown. FIG. 2 is an enlarged cross-sectional view of the screw shape of the connection screw portion. FIG. 2A shows the screw shape of both screw portions in an enlarged manner, and FIG.

In the illustrated steel pipe pile 1, the pile main body 2 is formed of a centrifugally cast steel pipe, and the connecting portion 3 is integrally formed as the steel pipe pile 1 by welding a separately cast separate member to the pile main body 2. I have. The connecting portion 3 has the same welded portion 17 as that of the steel pipe pile in both the inner and outer diameters, and has a thicker portion at the tip portion 3b side, and the connecting screw portion 4 is formed in the thickened portion 16. A parallel multi-thread screw is screwed into the connection screw portion 4, and a thread 12 of the multi-thread screw is formed in a trapezoidal shape.
The thread surface 1 on the tip 3b side of the screw thread 12 (corresponding to the tip end side of the male thread portion 6) is changed by changing the gradient of the thread surface 13 before and after the thread.
Welded part 1 in which the flank angle α1 of 3a is set small
The flank angle α2 on the 7 side (corresponding to the base end side of the male screw section 6)
(Fig. 2).
The angle (α1 + α2) of the screw thread 12 may be set so that the shear stress acting on the screw thread 12 when the external bending force is applied to the connection screw portion 4 becomes substantially uniform from the peak to the valley. Preferably, it is preferable that at least the shear stress acting on the thread on the crest side is not greater than the shear stress acting on the thread on the trough side. The flank angle α2 of the screw surface 13b on the base end side of the screw thread 12 is preferably small, and the smaller the flank angle α2 is, the smaller the flank angle α2 is.
The radially outward component acting on the female screw portion 5 is reduced by the tensile force applied when a bending external force is applied to the female screw portion, thereby preventing the female screw portion 5 from separating from the male screw portion 6. it can.

The connecting portion 3 has one end connecting portion 8 having a female screw portion 5 welded to one end of the pile main body 2 and the other end connecting portion having a male screw portion 6 welded to the other end. The internal thread 9 and the external thread 6 are connected to each other by screwing the female thread 5 and the external thread 6 so that the minimum inner diameters of the thickened portions 16 are equal (continuously in the coupled state). (So as to form an inner peripheral surface).

The one end side connecting portion 8 includes the thickening portion 16
The inner peripheral side on the side of the distal end portion 3b is formed with an internal stepped portion 8a to form the female screw portion 5 whose diameter is increased, and the other end side connecting portion 9 is provided with the distal end portion 3b of the thickened portion 16. An outer step 9a (corresponding to the step 1b of claim 3) is formed on the outer peripheral side to form the male screw portion 6 whose diameter is reduced, and the male screw has a thread diameter equal to the connecting portion 3. The outer diameter of the external thread 3a is made smaller than that of the outer thread 3a, and the thickness of the female thread 5 is ensured so that the thickness of the male thread 6 and the thickness of the female thread 5 are substantially equal. The outer step 9a serves as a contact surface 7 that can contact an end surface 8b (corresponding to the end surface 1c of the third embodiment, that is, equivalent to the end surface 1c of the steel pipe pile 1) at the tip end of the one end side connection portion 8. In this way, the length of the male screw portion 6 is made equal to the length of the female screw portion 5 (so that at least the length of the male screw portion 6 is not shorter than the length of the female screw portion 5). With such a configuration, at least the end face 8 b of the one end side connection part 8 is in a state where the connection screw part 4 is connected.
Is strongly pressed against the outer step portion 9a of the other end side connecting portion 9, so that an external bending force is applied to the connecting portion 3 connecting the upper and lower steel pipe piles 1, and a pulling force acts on the pulling side. However, since the separation of the end surface 1c from the outer step 9a on the pulling side can be prevented, the female screw 5 is separated from the male screw 6 radially outward at the distal end 3b as in the related art. This can prevent the bending strength from being reduced.

Next, another embodiment of the present invention will be described. <1> In the above embodiment, the example in which the screw thread is formed in a trapezoidal shape has been described, but the screw thread may be formed in a rectangular shape. That is, if both the flank angle α1 and the flank angle α2 are set to zero, when a bending external force is applied to the connecting portion 3, a component force acting on the male screw portion 6 and the female screw portion 5 in the pipe diameter direction is applied. Can be substantially eliminated, so that the deformation of the connection screw portion 4 can be prevented, and the bending strength of the connection portion 3 can be enhanced. It should be noted that, when the male screw portion 6 is fitted into the female screw portion 5, a positioning guide may be provided by another means. For example, the male screw part 6, the female screw part 5
In both cases, a screwless portion is provided at the tip 3b, and the tip 3b is provided.
The alignment can also be guided by tapered chamfering the screwless portion. <2> In the above embodiment, the example in which the thread 12 of the connecting screw portion 4 is formed in a trapezoidal shape with different base angles is shown. For example, as shown in FIG. If the screw thread and the thread groove are formed, rotation is easy, and the male screw portion 6 of the other end side connecting portion 9 is screwed into the one end side connecting portion 8 forming the female screw portion 5. When the end face 8b of the one end side connection portion 8 is in contact with the outer step 9a of the other end side connection portion 9, the female screw portion 6 is tightened.
Is in contact with the screw surface 13a on the distal end 3b side of the female screw portion 5 on the screw surface 13a on the distal end portion 3b side.
They are separated from each other. Here, the upper steel pipe pile 1
Is lifted, and further rotated and screwed in, the separated screw surfaces 13b can be brought into close contact with each other. This ends the tightening, but since the end face 8b and the outer step 9a are in close contact with each other, the upper and lower steel pipe piles 1 are surely secured.
Can be connected in a state where a compressive stress is applied to the connecting portion 3.
Although the screw thread is shown as having a rectangular cross section in FIG. 3, the screw thread may have a trapezoidal cross section shown in FIG. 1 or FIG. <3> In the example shown in FIG. 3 described above, the screw thread 12 of the connection screw part 4 is formed in a rectangular shape in which the flank angles of the screw faces 13 on both sides are 0 °. When the steel pipe piles 1 are fastened to each other at the connecting portion 3, there is no generation of a radial component corresponding to the fastening force due to the screw surface 12, so that the bending when external bending force acts on the connected steel pipe piles 1. It is possible to prevent the female screw portion 5 hitting the outside of the radius from being separated from the male screw portion 6, and to suppress a decrease in bending strength. Further, as described above, the backlash is increased, for example, the height of the screw thread is reduced to, for example, about 25 to 30% with respect to the screw pitch, and the width of the screw thread is set to 55 with respect to the width of the screw root. ~ 6
If it is narrowed to about 0%, the tip 3b of the connecting screw 4
Even if there is some irregularity in the shape of the incomplete screw portion formed at the screw end portion on the side, it is possible to suppress the obstruction of the male screw portion 6 from being screwed into the female screw portion 5. As described above, the height of the screw thread can be reduced because a large tensile strength in the length direction of the steel pipe pile is not required for the connecting screw portion. That is, it suffices to withstand the downward tensile force when suspending the steel pipe pile connected to the lower side and the longitudinal tensile force accompanying the external bending force applied to the connected steel pipe pile. <4> In the above <2> or <3>, the male screw portion 6 on the distal end portion 3b side of the connection screw portion 4 (see FIG. 1).
If the incompletely threaded portion of the female thread portion 5 is deleted, when the male thread portion 6 is screwed into the female thread portion 5 of the connecting portion 3,
It is possible to prevent improper engagement due to imperfect thread ends, and to start normal engagement. Furthermore, the correction shaping operation of the screw end after the removal of the burrs of the screw end on the tip 3b side after the screw processing, or after the screwless part on the tip 3b side is cut and formed after the screw processing. Can be omitted.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The concrete construction of the connecting portion of the steel pipe pile of the present invention described in the above embodiment will be described below. The pile main body 2 of the steel pipe pile 1 is a centrifugal force cast steel pipe pile having an outer diameter of 300 mm and a wall thickness of 39 mm.
And are integrally welded. The connecting portion 3 has an outer peripheral portion 3a having the same diameter as the outer peripheral portion 2a of the pile main body 2 (the outer peripheral portion 1a of the steel pipe pile 1), and is formed thicker than the pile main body 2 to have a thickness of 86 mm. The welded portion 17 connected to the pile main body 2 has the same inner diameter as the pile main body 2 by gently expanding the inner diameter, and has a thickness of 39 mm.
The connecting screw portion 4 is formed in the thickened portion 16 on the side. One end side connecting portion 8 connected to the other end side of the pile main body 2 is provided with an inner step portion 8a between itself and the inner peripheral portion of the thickened portion 16, and
The female screw part 5 is formed over the entire length of the pile body 2, and the other end side connecting part 9 connected to one end side of the pile main body 2 is provided with an outer step part 9 a between the outer peripheral part 3 a at the position of the thickened part 16. The male screw portions 6 are formed over 180 mm, and each has a total length of 328 mm. The male screw part 6
And the pitch circle between the female screw portion 5 and the female screw portion 5 is located at the center of the thickness of the thickened portion 16.

A parallel trapezoidal screw is screwed into the connection screw portion 4. Both the male screw portion 6 and the female screw portion 5 have a flank angle of the screw surface 13 a on the tip 3 b side of the thread 12 of the trapezoidal screw. α1 is 28.13 °, and the welded portion 17 of the thread 12 is
The flank angle α2 of the screw surface 13b on the side is 11.87 °, the angle of the screw thread is 40 ° (see FIG. 2), the height of the screw thread is 3.17 mm, and the pitch of the screw is 8.56.
mm, and thus the lead is formed to 25.68 mm, and
It is screwed as a triple thread over 80 mm.

[0016]

As described above, according to the present invention,
The upper and lower steel pipe piles can be connected to each other in a short time without reducing the strength of the connection part of the steel pipe piles.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view of an essential part for explaining an example of a connecting portion of a steel pipe pile according to the present invention.

FIG. 2 is an explanatory longitudinal sectional view of an essential part for explaining details of a screw of a connecting part shown in FIG. 1;

FIG. 3 is an explanatory longitudinal sectional view of an essential part for explaining details of another example of a screw of a connecting part.

FIG. 4 is an explanatory longitudinal sectional view of an essential part for explaining an example of connection of a conventional steel pipe pile.

FIG. 5 is a vertical sectional view of a main part for explaining another example of a connecting portion of a conventional steel pipe pile.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel pipe pile 1a Peripheral part of steel pipe pile 1b Step part of steel pipe pile 1c End face of steel pipe pile 4 Connection screw part 5 Female screw part 6 Male screw part 7 Contact surface 13 Screw surface

Claims (3)

[Claims] A female screw part (5) screwed at one end of one steel pipe pile (1) connected vertically and a male screw screwed at the other end of the other steel pipe pile (1). A connection part of a steel pipe pile provided with a connection screw part (4) for screwing and connecting the part (6), wherein the connection screw part (4) is formed by a multi-row parallel screw. Connection. 2. The flank angle of the male screw part (6) on the distal end side is made larger than the flank angle of the male screw part (6) on the base end side, and the female screw part (5) is formed. The connection portion of a steel pipe pile according to claim 1, wherein the thread surface (13) is formed along the thread surface (13) of the male thread portion (6). 3. The male screw part (6) and the steel pipe pile (1).
A step (1b) is provided between the outer thread (1a) and the outer diameter of the steel pipe pile (1) so that the external thread (6) has a smaller diameter than the outer diameter of the steel pipe pile (1). (1b) is connected to the end face (1) of the female screw portion (5).
3. The connecting part of a steel pipe pile according to claim 1, wherein c) is configured as a contactable contact surface (7).