JP2016084621A - Steel pipe connection joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel pipe connection joint that is hard to uncouple without extending a thread part length when a tension load is applied.SOLUTION: A connection joint 1 for a steel pipe according to this invention is a steel pipe connection joint that is fit on an end of a steel pipe 3 constituting a structure to be installed underground and connects the steel pipes 3 with each other. The connection joint comprises: a male side cylindrical body 5, which has a male screw that is parallel screw and made from multiple thread and has a junction with the steel pipe 3 at one end; and female side cylindrical body 7, which has a female screw that is parallel screw and made from multiple thread and has a junction with the steel pipe 3 at one end. In a state where the male side cylindrical body 5 and the female side cylindrical body 7 are connected, centers of the male screw and the female screw are matched with the center of the junction in plate thickness direction.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a steel pipe joint that joins steel pipes constituting a structure to be placed in the ground, such as a steel pipe pile, a steel pipe sheet pile, and a built-up column.

Some steel pipe piles for preventing landslides and long support piles have a diameter of about 200 to 1500 mm and a length of several tens of meters depending on the conditions of the construction site.
In such a case, it is necessary to join short steel pipe piles at the construction site in the middle of placing the piles, and for this joining, joint joints attached to respective ends of the steel pipe piles to be joined are used.

As an example of such a joint, there is a “joint joint of steel pipe piles” disclosed in Patent Document 1.
As shown in FIG. 8, the steel pipe pile joint 31 has a male cylinder 33 having a male thread joined to one end of the steel pipe pile to be joined, and a female thread joined to the other steel pipe pile end. The female side cylindrical body 35 is composed of three or more parallel threaded screws, and a cylindrical portion 37 having an outer diameter loosely fitted to the inner diameter of the female thread is provided at the tip of the male side cylindrical body. (See claim 1 of Patent Document 1).

Japanese Patent Laid-Open No. 10-311028

FIG. 9 schematically shows the vicinity of the conventional joint joint 31 shown in FIG. 8, and the outer peripheral surface of the base end side of the male side cylindrical body 33 and the outer peripheral surface of the female side cylindrical body 35 are substantially the same. It is the same. In order to make such a structure, the male cylinder 33 is formed with a cylinder so as to project inward from the base end side, and a male screw is formed on the outer peripheral surface of the cylinder.
When an overall bending load as shown by an arrow in FIG. 9 acts, a compressive force acts on the left side of the joint joint 31 in the figure, and a tensile force acts on the right side in the figure.
In the portion where the tensile force acts, as shown in FIG. 10 showing the portion surrounded by the long circle in FIG. 9, there is a slight disconnection due to the entire bending load.
Further, as described above, the male cylinder 33 is formed so as to project inward from the base end side, and when a tensile load acts on the joint joint 31 having such a structure, the male cylinder 33 In 33, as shown by the broken line in FIG. 11, a force flows from the meshing portion of the screw to the center on the base end side once through the vicinity of the center of the overhang portion. For this reason, as shown by M in FIG. 11, a large deviation occurs in the force transmission path. Due to this deviation, local bending acts on the circled portion of FIG. 12 and joint disengagement occurs. When this local bending becomes large, the joint disengagement due to the overall bending and the joint disengagement due to the local bending are combined, so that the joint is completely detached, and there is a possibility that the load cannot be transmitted.
For this reason, the length of the threaded part has been increased so that the load can be transmitted even if some of the screws are disengaged, or the height of the thread is increased. Measures such as connecting cylinders were required, which caused the joint to increase in size and cost.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a steel pipe joint that does not easily come off when a tensile load is applied without increasing the length of a threaded portion. .

(1) A steel pipe joint according to the present invention is a steel pipe joint that is attached to an end of a steel pipe constituting a structure to be placed in the ground and joins the steel pipes together.
A male cylindrical body having a male screw made of a multi-threaded screw with a parallel screw and one end side being a joint portion with the steel pipe, and a female thread having a female screw made of a multi-threaded screw with a parallel screw and one end side being a joint portion with the steel pipe A female side cylinder body,
In the state where the male cylinder and the female cylinder are joined, the center of the male screw and the female screw and the center in the plate thickness direction of the joint are aligned. It is.

(2) Further, in the above-described (1), the male side tubular body has a reduced diameter portion that protrudes inward and has an outer diameter reduced, and the outer diameter of the reduced diameter portion is A male screw is formed, the female side tubular body has an enlarged diameter portion that projects outward and an outer diameter is enlarged, and the female screw is formed on an inner surface of the enlarged diameter portion. It is a feature.

(3) Further, in the above-described (1) or (2), an inclined surface that is point-symmetric with respect to the center of the cylinder axis and that is inclined in the radial direction is provided at the tip of the female cylinder. And forming an inclined surface having the same inclination direction and inclination angle as the inclined surface over the entire circumference on the male side cylinder,
In the state where the male screw of the male cylinder is screwed and tightened, the inclined surface of the tip of the female cylinder is in contact with the inclined surface formed on the male cylinder.

(4) Further, in the above (3), the inclination angle of the inclined surface is set in a range of 5 degrees to 25 degrees.

(5) Moreover, in the thing in any one of said (1) thru | or (4), between the base end side of the said male side cylinder and the front end side of the said female side cylinder, and the said male side cylinder An inlay structure is provided between the distal end side and the proximal end side of the female cylinder, respectively.

In the steel pipe joint according to the present invention, the male side cylindrical body having a male thread made of a multi-thread with parallel threads and one end of which is a joint with the steel pipe, and the female thread made of a multi-thread with a parallel thread are provided. And having a female side tubular body whose one end is a joint with the steel pipe,
In the state where the male cylinder and the female cylinder are joined, the center of the male screw and the female screw and the center of the joint portion in the plate thickness direction coincide with each other. The local bending that occurs when this occurs is reduced, and the joint portion is less likely to come off. Therefore, it is not necessary to lengthen the threaded portion in order to prevent the joint portion from coming off, and the joint joint can be made compact.

It is explanatory drawing of the principal part of the joint joint which concerns on one embodiment of this invention. It is explanatory drawing explaining the effect | action when a tensile load acts on the principal part of the joint joint shown in FIG. It is explanatory drawing explaining the other characteristic point of the joint joint which concerns on one embodiment of this invention. It is explanatory drawing explaining the effect | action of the joint joint which concerns on one embodiment of this invention. It is explanatory drawing explaining the appropriate range of the inclination angle of the joint joint which concerns on one embodiment of this invention. It is explanatory drawing of other embodiment of this invention. It is an enlarged view which expands and shows a part of FIG. It is explanatory drawing of a prior art example. It is explanatory drawing explaining the subject of a prior art example (the 1). It is explanatory drawing explaining the effect | action when tensile force acts on the site | part enclosed by the long circle of FIG. It is explanatory drawing explaining the subject of a prior art example (the 2). It is explanatory drawing explaining the subject of a prior art example (the 3).

[Embodiment 1]
A steel pipe joint 1 according to an embodiment of the present invention (hereinafter simply referred to as “joint joint 1”) is attached to an end of a steel pipe 3 constituting a structure to be placed in the ground, and the steel pipes 3 are connected to each other. As shown in FIG. 1, the steel pipe 3 has a male pipe 5 and a female pipe 7.

  The male side cylinder 5 has a male screw composed of a multi-threaded screw with a parallel screw, and a male side joint portion 9 to be welded to the steel pipe 3 is formed on the base end side. The male side cylinder 5 has a reduced diameter portion 11 that protrudes inward and has an outer diameter reduced, and a male screw is formed on the outer surface of the reduced diameter portion 11.

  The female side cylindrical body 7 has female threads made of multiple threads with parallel threads, and a female side joint portion 13 that is welded to the steel pipe 3 is formed on the proximal end side. The female-side cylinder 7 has a diameter-expanded portion 15 that projects outward and has an increased outer diameter, and a female screw is formed on the inner surface of the diameter-expanded portion 15.

In a state in which the male cylinder 5 and the female cylinder 7 are joined, the center of engagement between the male screw and the female screw and the center in the thickness direction of the joint portion are configured to coincide with each other. In FIG. 1, the center of meshing and the center of the joint portion in the thickness direction are indicated by a one-dot chain line.
As described above, when the centers coincide with each other, local bending that occurs when a tensile load is applied is reduced, and the joint portion is difficult to come off.
In the case of a threaded joint, there is generally a clearance of several millimeters between the male screw and the female screw. In this specification, the center coincidence means that the deviation due to such clearance is an error range. "

FIG. 2 shows the flow of force when a tensile load is applied to the joint joint 1 shown in FIG.
As shown in FIG. 2, the eccentricity amount m of the force flow is smaller than the eccentricity amount M of FIG. 11 showing the conventional example. As a result, although some local bending occurs, In comparison, each stage is smaller.
For this reason, even if a tensile load is applied, the joint joint 1 is difficult to come off. In other words, when securing the same difficulty as in the conventional example, the length of the threaded portion can be shortened. The joint 1 can be made compact.

In addition, as another feature, the joint joint 1 of the present embodiment is point-symmetric with respect to the center of the cylinder axis on the entire circumference of the female-side tip of the female-side cylinder 7 as shown in FIG. A female-side inclined surface 17 having an inclination angle α that is inclined downward in the radially outward direction with the tip portion directed upward is formed.
On the other hand, the male side inclined surface 19 having the same inclination direction and the same inclination angle as the female side inclined surface 17 in the joined state is provided on the outer peripheral seat on the proximal end side of the male side cylindrical body 5.
In the state where the male side cylinder 5 is screwed and tightened, the female side inclined surface 17 and the male side inclined surface 19 abut.
In order for the female-side inclined surface 17 and the male-side inclined surface 19 to come into contact with each other, as shown in FIG. 3, in the state where the male-side cylindrical body 5 is screwed and tightened, What is necessary is just to make it produce a clearance gap between the inner peripheral seats 23 of the female side cylinder 7. FIG. But you may make it the front-end | tip part of the male side cylinder 5 and the inner peripheral seat 23 of the female side cylinder 7 contact | abut simultaneously with the completion of joining by the joint joint 1. FIG.
In addition, the preferable value of inclination-angle (alpha) of the front-end | tip part of the female side cylinder 7 is mentioned later.

The operation of the female inclined surface 17 and the male inclined surface 19 configured as described above will be described.
Immediately before the completion of screwing, the female-side inclined surface 17 formed on the female-side cylinder 7 abuts on the male-side inclined surface 19 formed on the male-side cylinder 5, and the clearance is determined by the contact and the pressing force generated by the rotation of the screw. An effect of automatically adjusting the misalignment based on this occurs.
Hereinafter, this point will be described in detail with reference to FIG.

FIG. 4A is a longitudinal sectional view in a state where a part of the female inclined surface 17 and the male inclined surface 19 are in contact with each other just before the screwing is completed.
As shown in FIG. 4A, immediately before the completion of screwing, the female side inclined surface 17 and the male side inclined surface 19 may be shifted in the horizontal direction due to the influence of the clearance provided in the threaded portion. At this time, if the male-side inclined surface 19 on the upper side in the drawing is shifted to the right in the drawing as shown in FIG. 4A, the male-side inclined surface 19 is in a horizontal state. Since the male side inclined surface 19 and the female side inclined surface 17 on the left side in the drawing are in contact with each other, the male side inclined surface 19 and the female side inclined surface 17 are in contact with each other. There is no gap.
In this state, when the male side cylinder 5 is rotated and the final screwing is performed, the male side inclined surface 19 existing on the upper side is guided by the female side inclined surface 17 existing on the lower side so that the inclined surface slides. Thus, the state shown in FIG.
In this way, when the screwing is completed, the female side cylinder 7 and the male side cylinder 5 are automatically aligned in a state where the axial centers thereof coincide with each other.

  If the inclination angle α is too small, the effect of guiding the male cylinder 5 when screwing is completed is reduced. Conversely, if the inclination angle α is too large, the function of transmitting the compressive load on the contact surface is impaired. Therefore, since a preferred range of the inclination angle α has been studied, this point will be described below.

FIG. 5 is a graph showing the relationship between the tilt angle, the misalignment correction force, and the load transmission function. The horizontal axis represents the tilt angle α, the left vertical axis represents the misalignment correction force, and the right vertical axis. Indicates the soundness of the load transfer function.
As shown in FIG. 5, the misalignment correction force increases as the inclination angle α increases. On the other hand, when the inclination angle is greater than or equal to a certain value (25 degrees), the soundness of the load transmission function is inhibited.
Therefore, the range of the inclination angle α that can ensure the soundness of the load transmission function while exhibiting the correction force is preferably 5 degrees or more and 25 degrees or less.

  The first aspect of the present invention is that, in the state where the male side cylinder 5 and the female side cylinder 7 are joined, the center of engagement between the male screw and the female screw and the center of the joint portion in the plate thickness direction coincide with each other. The point which provides the female side inclined surface 17 and the male side inclined surface 19 which contact | abut in a joining state is not essential.

[Embodiment 2]
As shown in FIGS. 6 and 7, the joint joint 25 of the present embodiment is free to play axially with respect to the distal end portion of the female side cylinder 7 and the radially inner side of the inclined surface of the outer peripheral seat of the male side cylinder 5. The loose fitting part 27 (inlay structure) to be fitted is formed over the entire circumference.
6 and 7, as an example of the loose fitting portion 27, an annular convex portion 27 a is provided at the distal end portion of the female side cylindrical body 7, and the convex portion 27 a is loosely provided on the outer peripheral seat of the male side cylindrical body 5. An annular groove 27b to be fitted is provided.

  By providing the loose fitting portion 27, when the bending force acts on the joined steel pipe 3 and the joint joint 25 is curved, the screw in which the female cylinder 7 and the male cylinder 5 are screwed together. Can be prevented from coming off.

  Even when the convex portion 27a and the concave groove 27b are provided, in order for the female side inclined surface 17 and the male side inclined surface 19 to abut when the joint joint 25 is screwed, the convex portion 27a and the concave groove 27b are brought into contact. As shown in FIG. 7, a gap is formed between the two.

1 Joint (Embodiment 1)
DESCRIPTION OF SYMBOLS 3 Steel pipe 5 Male side cylinder 7 Female side cylinder 9 Male side joined part 11 Reduced diameter part 13 Male side joined part 15 Diameter enlarged part 17 Female side inclined surface 19 Male side inclined surface 21 Male side front end part 23 Inner peripheral seat 25 Bonded joint (Embodiment 2)
27 Free fitting portion 27a Convex portion 27b Concave groove

Claims (5)

A steel pipe joint that is attached to an end of a steel pipe constituting a structure to be placed in the ground and joins the steel pipes,
A male cylindrical body having a male screw made of a multi-threaded screw with a parallel screw and one end side being a joint portion with the steel pipe, and a female thread having a female screw made of a multi-threaded screw with a parallel screw and one end side being a joint portion with the steel pipe A female side cylinder body,
A steel pipe characterized in that, in a state in which the male cylinder and the female cylinder are joined, the center of the male screw and the female screw and the center of the joining portion in the plate thickness direction coincide with each other. Joint fitting.   The male cylinder has a reduced diameter portion that projects inward and has an outer diameter reduced. The male screw is formed on the outer surface of the reduced diameter portion, and the female cylinder has an outer diameter. The steel pipe joint according to claim 1, wherein the steel pipe has a diameter-expanded portion extending outward and having an outer diameter expanded, and the female thread is formed on the inner surface of the diameter-expanded portion. An inclined surface that is point-symmetric with respect to the center of the cylinder axis and is inclined in the radial direction is formed at the distal end portion of the female-side cylinder over the entire circumference, and the inclined surface and the inclination direction are formed on the male-side cylinder. And an inclined surface having the same inclination angle is formed over the entire circumference,
The inclined surface of the tip of the female cylinder is in contact with the inclined surface formed on the male cylinder when the male screw of the male cylinder is screwed and tightened. 2. A steel pipe joint according to item 2.   The steel pipe joint according to claim 3, wherein an inclination angle of the inclined surface is set in a range of 5 to 25 degrees.   An inlay structure is provided between the proximal end side of the male cylinder and the distal end side of the female cylinder, and between the distal end side of the male cylinder and the proximal end side of the female cylinder. The steel pipe joint according to any one of claims 1 to 4, wherein the steel pipe joint is provided.