JP2004068273A - Tube end sealing structure and the sealing method of steel pipe expansion type lock bolt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tube end sealing structure which can be easily and securely sealed when a sleeve is pressed in the end of a deformed tube, weld the tube end and the sleeve to seal the tube end of a steel pipe expansion type lock bolt. <P>SOLUTION: When the sleeve 2 is pressed in both ends of a deformed pipe 1 by using a pressing metal implement 3, an implement having a shape that a cylindrical part 5 having such an outer diameter that a length as long as four times of the plate thickness is deduced from the sleeve inner diameter and a conical part 4 are assembled together is used to press-in the sleeve 2 and deform the inner face of both deformed pipe 1 ends. A flat part 9 is formed from the pipe ends to closely attach the mutual inner faces in the deformed pipe to each other and the deformed pipe outside face is closely attached to the sleeve inside face, then the sleeve and the deformed pipe ends are welded together 8 to obtain a pipe end sealed structure of a highly airtight steel pipe extension type lock bolt. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention is a variant of a steel pipe expansion type lock bolt for filling a pipe in a hole provided in a rock by reinforcing a rock by injecting a fluid into the inside and radially expanding the pipe by a fluid pressure. The present invention relates to a tube end sealing structure and a sealing method thereof.
[0002]
[Conventional technology and its problems]
To seal the end of the deformed pipe, a sleeve for completely sealing one end and providing a seal and a fluid inlet at the other end is provided at both ends of the lock bolt deformed pipe having a concave section. After press-fitting and pushing a pressing die having a conical shape into the inside of the deformed pipe end into which the sleeve is press-fitted to bring the pipe inner surfaces into close contact with each other, the pipe end end and the pipe end and the sleeve are joined by welding. ing.
That is, in order to press-fit a cylindrical sleeve 2 into a deformed tube 1 having a cross-sectional shape as shown in FIG. 1 and to bring the inner surfaces of the ends of the deformed tube 1 constituting the lock bolt into contact with each other, FIG. The pressing mold 3 is pressed from both ends as described above.
[0003]
As the pressing die 3 for pressing from both ends, a pressing die having a conical portion 4 at the tip as shown in FIG. 3 is used. As shown in FIG. 4 (a), when the cylindrical sleeve 2 is press-fitted and the pressing mold 3 is pressed to deform the inner surface of the end of the deformed tube 1 constituting the lock bolt, the lock bolt deformed tube is deformed. As shown in FIG. 4B, the positional relationship between the end and the sleeve is such that the inner surfaces of the tube ends of the deformed tubes are in contact with each other, and the outer surface of the tube end is in close contact with the inner surface of the sleeve. Reference numeral 6 in the figure is a spacer for securing a weld joint between the end of the deformed pipe 1 and the sleeve 2.
[0004]
Thereafter, when the tube end and the tube end of the deformed pipe 1 are joined to the sleeve 2 by welding, as shown in FIG. 4 (c), burn-through defects 7 easily occur at the inner surface end of the deformed pipe. . Even if it does not melt through, the area of the weld joint is reduced, and the pressure resistance of the lock bolt as a pressure body is likely to be reduced. Reference numeral 8 denotes a weld between the end of the deformed pipe and the sleeve.
In particular, if a plated steel pipe having excellent corrosion resistance is used as a deformed pipe for a rock bolt from the viewpoint of improving durability, welding defects such as pinholes and blowholes are likely to occur due to plating vapor during welding. As a countermeasure, it is necessary to increase the amount of molten metal at the time of welding. However, if the amount of heat of welding is increased, the welding heat causes a burn-through defect 7 in the work deformation abutting portion inside the deformed pipe for a lock bolt. Confidentiality is easily lost.
In order to suppress the occurrence of burn-through defects, it is necessary to set welding conditions strictly, and as a result, workability is reduced.
[0005]
The present invention has been devised to solve such a problem. By adjusting the shape of a welded joint at the end of a deformed pipe for a lock bolt, a sleeve is pressed into the end of the deformed pipe. Therefore, it is an object of the present invention to provide a pipe end sealing method for easily and reliably sealing a pipe end of a steel pipe expansion type lock bolt by welding and joining a pipe end and a sleeve.
[0006]
[Means for Solving the Problems]
In order to achieve the object, the pipe end sealing structure of the steel pipe expansion type lock bolt of the present invention includes a sleeve tightly covered on both outer surfaces of both ends of the deformed tube for a lock bolt, and an inner surface having a flat portion from the pipe end side. Are formed, and the deformed pipe ends which are in close contact with each other are welded and sealed to each other at the ends.
When the sleeve is press-fitted to both ends of the deformed pipe using a press fitting, the sealing structure has a cylindrical shape having an outer diameter of a dimension obtained by subtracting four times the plate thickness from the inner diameter of the sleeve. Using a shape in which the part and the conical part are integrally combined, press-fitting the sleeve and deforming the inner surface of both ends of the deformed pipe, forming a flat part from the pipe end side, and bringing the inner surfaces of the deformed pipe into close contact with each other After the outer surface of the deformed pipe is brought into close contact with the inner surface of the sleeve, the sleeve and the end of the deformed pipe are welded to each other at the ends.
As the deformed pipe, a pipe formed of a Zn-based plated steel pipe such as Zn, Zn-Al-based, or Zn-Al-Mg-based is preferable.
[0007]
Embodiment
The present inventors have conducted intensive studies on a method for reliably performing a welding connection between a deformed pipe end in which the pipe end inner surfaces are in contact with each other and an end of a sleeve that is in close contact with the deformed pipe outer surface. Was.
In the process, when the inner surface of the concave portion of the deformed pipe having the inflated concave portion is normally brought into contact with the curved portion and welded to the sleeve end including the abutting portion, the deformed pipe inner surface tip welding joint portion of the inflated concave portion is used. Are in line contact (see FIG. 4b), so that the space inside the line contact portion easily melts off (see FIG. 4c), and as a result, the airtightness of the lock bolt is reduced. I confirmed that it would lead to chipping.
[0008]
Therefore, the contact between the inner surfaces of the deformed pipes provided with the expansion recesses is changed from a line contact type to a surface contact type. Suppression and airtightness could be secured.
That is, when pressing the pressing die 3 to deform the inner surface of the end of the deformed tube 1 constituting the lock bolt by press-fitting the cylindrical sleeve 2, the pressing fitting 3 is used as the pressing fitting 3 as shown in FIG. When a shape in which the shape portion 5 and the conical shape portion 4 are integrally combined is used, the inner surface of the deformed tube 1 forms a flat portion from the tube end side by the action of the cylindrical shape portion 5 and adheres to each other.
[0009]
This will be described in detail with reference to FIG. When the outer diameter of the cylindrical portion 5 of the press fitting 3 in which the cylindrical portion 5 and the conical portion 4 are integrally combined is a size obtained by subtracting four times the plate thickness from the inner diameter of the sleeve 2. When the tube is pushed in from the end of the deformed tube 1, the inner surface of the expansion concave portion of the deformed tube 1 forms a flat portion 9 from the end side to the inner surface of the normal curved portion so as to be closely attached (FIG. 6). a). Even after the pressing fitting 3 is removed, the inner surfaces of the deformed tube 1 form a flat portion 9 and are in close contact with each other, and the outer surface of the deformed tube 1 is in close contact with the inner surface of the sleeve 2 (FIG. 6B). . In this state, when the deformed tubes 1 are welded to each other and the tube end of the deformed tube 1 and the sleeve 2 are welded, the deformed tubes 1 form a flat portion 9 and are in close contact with each other. Since there is close contact, there is no space to melt down, and even if the heat of welding is increased, the concave side of the deformed pipe for a lock bolt does not melt down. Since the area of the inner surface contact portion of the deformed pipe becomes large, and the welded portion 8 is securely formed in the region including the inner surface contact portion of the deformed tube and the sleeve, not only airtightness can be ensured, but also the pressure resistance is reduced. It has an enlarged sealing structure.
[0010]
The formation of the flat portion 9 can suppress burn-through, so that the volume of the molten metal can be increased. Therefore, even if a plated steel pipe is used as a rock bolt material, it is difficult for defects such as pinholes and blowholes caused by plating vapor to reach the surface of the welded portion, and welding defects can be prevented. Thus, it is possible to reliably prevent water leakage when the pipe body is expanded in the radial direction.
The length of the flat portion can be appropriately set depending on the strength of the steel pipe constituting the lock bolt, the pipe diameter and the length of the lock bolt.
[0011]
【Example】
A sleeve made of a commercially drawn 400N-class drawn steel pipe having an outer diameter of 41.3 mm, an inner diameter of 33.0 mm, and a length of 70 mm is placed on the pressure water injection side of a pipe end of a 2 mm thick rock bolt deformed pipe having a plate thickness of 2 mm. About 5 mm was temporarily press-fitted. A sleeve having the same material, an outer diameter of 38.1 mm, an inner diameter of 33.0 mm, and a length of 70 mm was temporarily press-fitted to the other end sealing side of the deformed pipe by about 5 mm.
At both ends of a galvanized rock bolt shaped tube having a recess for expansion into which a sleeve has been temporarily press-fitted, a conical portion with a tip angle of 45 degrees and a cylindrical portion having a height of about 7.5 mm and an outer diameter of 24.3 mm Was inserted, and both ends were lowered with a hydraulic cylinder while the pressing die was inserted. At that time, a spacer having the same diameter as that of the sleeve and a thickness of 7.5 mm was attached to the mold so that the pipe end of the deformed pipe for the lock bolt was located at a position about 7.5 mm inside the end of the sleeve.
After press-fitting to a predetermined position, the mold was pulled out. As a result, a press-fit body was obtained in which the inner surface of the concave portion of the deformed tube for lock bolt was in close contact with the inner surface of the sleeve side for about 7.5 mm, and the outer surface of the deformed tube was in close contact with the inner surface of the sleeve. When the deformed pipe end of the press-fitted body was joined to the sleeve by welding, a lock bolt having no burn-through and no welding defects such as pinholes and blowholes was obtained.
[0012]
【The invention's effect】
As described above, in the method for sealing a pipe end of a steel pipe inflatable lock bolt of the present invention, a cylinder having an outer diameter of a dimension obtained by subtracting a dimension of four times the plate thickness from an inner dimension of the sleeve is used as the press fitting. Since the shape portion and the conical shape portion are integrally combined, the deformed pipe inner surfaces form a flat portion and are joined to each other, and the deformed pipe and the sleeve are firmly connected. For this reason, the hydraulic pressure range for expanding the steel pipe expansion type lock bolt can be widened, and the pressurization and expansion work of the steel pipe expansion type lock bolt can be performed efficiently and safely.
Further, even if a plated steel pipe is used as the steel pipe expansion type lock bolt material, burn-through can be suppressed, so that welding can be reliably performed, and the safety of the pressurization and expansion work is further improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a state in which a sleeve is press-fitted into a deformed pipe end. FIG. 2 is a view illustrating a process of press-fitting a sleeve into a deformed pipe end. FIG. FIG. 4 is a diagram illustrating a conventional tube end sealing process. FIG. 5 is a diagram illustrating a pressing mold shape used in the present invention. FIG. 6 is a diagram illustrating a tube end sealing process of the present invention. Explanation of code]
1: Deformed tube 2. Sleeve 3: Press fitting 4: Conical portion 5: Cylindrical portion 6: Spacer 7: Burnout defect 8: Weld 9: Flat portion

Claims (4)

The sleeves, which are tightly covered on the outer surfaces of both ends of the deformed pipe for lock bolts, and the deformed pipe ends, whose inner surfaces form a flat part from the pipe end side and are in close contact with each other, are welded and sealed at the ends. A pipe end sealing structure for a steel pipe inflatable lock bolt. The pipe end sealing structure of a steel pipe expansion type lock bolt according to claim 1, wherein the deformed pipe is a Zn-based plated steel pipe. When press-fitting the sleeve to both ends of the deformed pipe using the press fittings, the press-fitting includes a cylindrical part and a conical part having outer diameters of dimensions obtained by subtracting four times the plate thickness from the inner diameter of the sleeve. Using a united shape, press-fit the sleeve and deform the inner surface of both ends of the deformed tube, form a flat part from the tube end side, make the inner surfaces of the deformed tube adhere to each other, and attach the outer surface of the deformed tube to the sleeve. A method of sealing a pipe end of a steel pipe expansion type lock bolt, wherein the sleeve and the deformed pipe end are welded to each other at their ends after being brought into close contact with the inner surface. The method according to claim 3, wherein the deformed pipe is a Zn-based plated steel pipe.

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