JP4252776B2 - Pipe end sealing method for steel pipe expansion lock bolt - Google Patents

Description

[0001]
[Industrial application fields]
The present invention is a variant of a steel pipe expansion type rock bolt for reinforcing a rock by filling a pipe into a hole provided in a rock mass by injecting a fluid into the inside and expanding the pipe body in a radial direction by the fluid pressure. The present invention relates to a tube end sealing method .
[0002]
[Prior art and its problems]
The end of the deformed tube end is sealed at both ends of the deformed tube for a rock bolt having a recess having a concave cross section, and a sleeve for providing a seal and a fluid inlet at the other end. Press-fit, press the conical die into the inside of the deformed tube end into which the sleeve is press-fitted to bring the tube inner surfaces into close contact with each other, and then join the tube end and the tube end to the sleeve 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 bring the inner surfaces of the end portions of the deformed tube 1 constituting the lock bolt into contact with each other, as shown in FIG. Thus, the pressing mold 3 is pressed from both ends.
[0003]
As the pressing die 3 to be pressed from both ends, a die having a conical portion 4 at the tip as shown in FIG. 3 is used. As shown in FIG. 4A, when the cylindrical sleeve 2 is press-fitted and the pressing die 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 As for the positional relationship between the end and the sleeve, as shown in FIG. 4B, the inner surface of the deformed tube is in contact with the inner surface of the deformed tube, and the outer surface of the tube end is in close contact with the inner surface of the sleeve. In the figure, reference numeral 6 denotes a spacer for securing a weld joint between the pipe end of the deformed pipe 1 and the sleeve 2.
[0004]
Thereafter, when trying to join the pipe end and the pipe end of the deformed pipe 1 and the sleeve 2 by welding, as shown in FIG. 4 (c), a melt-off defect 7 is likely to occur at the inner face end of the deformed pipe. . Even if it does not melt off, the weld joint area is reduced, and the pressure resistance of the lock bolt as a pressure body tends to be low. Reference numeral 8 denotes a welded portion between the deformed pipe end and the sleeve.
In particular, if a plated steel pipe having excellent corrosion resistance is used as a deformed pipe for rock bolts 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 molten metal at the time of welding. However, if the amount of heat of welding is increased, a melt-off defect 7 occurs due to welding heat in the deformation contact portion inside the deformed pipe for the lock bolt, and the lock bolt As confidentiality is easily lost.
In order to suppress the occurrence of burn-through defects, it is necessary to strictly set the welding conditions, resulting in a decrease in workability.
[0005]
The present invention has been devised to solve such problems, and by adjusting the shape of the welded joint portion of the deformed pipe end for the lock bolt, the sleeve is press-fitted into the deformed pipe end. Thus, an object of the present invention is 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 the pipe end and a sleeve.
[0006]
[Means for Solving the Problems]
In order to achieve the purpose of the pipe end sealing method of the steel pipe expansion type lock bolt of the present invention, when the sleeve is press-fitted using a press fitting at both ends of the deformed pipe , Using a shape in which the cylindrical part and the conical part with the outer diameter of the dimension minus four times the plate thickness are combined together, press-fitting the sleeve and deforming the inner surface of both ends of the deformed pipe, A flat portion is formed from the tube end side so that the inner surfaces of the deformed tubes are in close contact with each other, and after the outer surface of the deformed tube is in close contact with the inner surface of the sleeve, the sleeve and the end of the deformed tube tube are welded together at the end. To do.
The deformed tube is preferably made of a Zn-based plated steel tube such as Zn, Zn-Al-based, Zn-Al-Mg-based.
[0007]
Embodiment
The inventors of the present invention have made extensive studies on a method for reliably performing welded joining between the deformed tube end portion in which the tube end inner surfaces are in contact with each other and the end portion of the sleeve in close contact with the outer surface of the deformed tube. It was.
In that process, when the concave inner surface of the deformed pipe formed with the expansion concave portion is brought into contact with the normal curved portion and welded to the sleeve end including the contact portion, the inner pipe tip welded joint portion of the expansion concave portion Is in line contact (see FIG. 4 b), and the space part entering from the line contact portion is likely to melt away (see FIG. 4 c), resulting in the airtightness of the lock bolt. I confirmed that it would lead to lack.
[0008]
Therefore, the contact between the inner surfaces of the deformed pipes provided with the recesses for expansion is changed from the line contact type to the surface contact type, and the welded joint part is widely secured to prevent the inner surface contact parts from being melted. Suppressed and secured airtightness.
That is, when the pressing mold 3 is pressed to deform the inner surface of the end of the deformed tube 1 constituting the lock bolt by press-fitting the cylindrical sleeve 2, a cylinder as shown in FIG. When the shape portion 5 and the conical shape portion 4 are integrally combined, 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 is brought into close contact with each other.
[0009]
This will be described in detail with reference to FIG. The outer diameter size of the cylindrical portion 5 of the press fitting 3 having a shape in which the cylindrical portion 5 and the conical shape portion 4 are integrally combined is a size obtained by subtracting a size four times the plate thickness from the inner diameter size of the sleeve 2. When the deformed tube 1 is pushed in from the tube end, the inner surface of the expansion recess of the deformed tube 1 is usually brought into close contact with the inner surface of the curved portion by forming a flat portion 9 from the end side (FIG. 6). a). Even after the pressing fitting 3 is removed, the inner surfaces of the deformed tubes 1 are in close contact with each other by forming a flat portion 9, 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 and the deformed tube 1 pipe end and the sleeve 2 are welded together, the deformed tubes 1 form a flat portion 9 and are in close contact with each other, and the deformed tube 1 end is on the inner surface of the sleeve 2. Since they are in close contact with each other, there is no space to melt, and even if the amount of heat of welding is increased, the concave side of the deformed tube for the lock bolt does not melt. The area of the inner surface contact portion of the deformed tube is increased, and the welded portion 8 is reliably formed in the region including the inner surface contact portion of the deformed tube and the sleeve, so that not only airtightness can be ensured but also the pressure resistance is reduced. Enlarged sealing structure.
[0010]
Since the melt-down can be suppressed by forming the flat portion 9, the amount of molten metal can be increased. For this reason, even if a plated steel pipe is used as the rock bolt material, defects caused by plating vapor such as pinholes and blowholes do not easily reach the weld surface, and it is possible to prevent welding defects and reduce fluid pressure. 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 and the diameter and length of the lock bolt.
[0011]
【Example】
A sleeve made of 400N class commercial drawn steel pipe with an outer diameter of 41.3 mm, an inner diameter of 33.0 mm, and a length of 70 mm on the pressure water injection side of the tube end of a 2 mm-thick rock bolt deformed pipe galvanized on both sides. About 5 mm was temporarily press-fitted. A sleeve of the same material, an outer diameter of 38.1 mm, an inner diameter of 33.0 mm, and a length of 70 mm was also temporarily press-fitted to the other end sealing side of the deformed tube by about 5 mm.
At the both ends of the deformed tube for galvanized rock bolts, which has a recess for expansion into which a sleeve is temporarily press-fitted, a conical portion with a tip angle of 45 degrees and a cylindrical portion with a height of about 7.5 mm and an outer diameter of 24.3 mm A pressing metal fitting was inserted, and both ends were pressed down with a hydraulic cylinder while the pressing mold was inserted. At that time, a spacer having the same diameter as the sleeve diameter and a thickness of 7.5 mm was attached to the mold in order to place the tube end of the deformed tube for lock bolt about 7.5 mm from 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 the lock bolt was in close contact with the inner surface on the sleeve side by 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 end of the deformed pipe of the press-fitted body and the sleeve were joined by welding, a rock bolt with no welding defects such as pinholes and blowholes was obtained.
[0012]
【The invention's effect】
As described above, in the pipe end sealing method of the steel pipe expansion type lock bolt of the present invention, as a pressing fitting, a cylinder having an outer diameter of a dimension obtained by subtracting a dimension four times the plate thickness from a sleeve inner diameter dimension. Since the shape portion and the conical shape portion are integrally combined, the inner surfaces of the deformed tubes are joined together to form a flat portion, and the deformed tube and the sleeve are firmly bonded. For this reason, the water pressure application range for expanding a steel pipe expansion type lock bolt can be taken widely, and pressurization and expansion work of a 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 rock bolt material, it is possible to suppress the melt-off, so that welding can be reliably performed, and the safety of pressurizing / expanding work is further improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a state where a sleeve is press-fitted into a deformed tube end. FIG. 2 is a diagram illustrating a process of press-fitting a sleeve into a deformed tube end. FIG. 3 illustrates a conventional pressing mold shape. FIG. 4 is a diagram for explaining a conventional tube end sealing step. FIG. 5 is a diagram for explaining a pressing die shape used in the present invention. FIG. 6 is a diagram for explaining a tube end sealing step of the present invention. Explanation of symbols]
1: Deformed pipe Sleeve 3: Press fitting 4: Conical shaped part 5: Cylindrical shaped part 6: Spacer 7: Burn-through defect 8: Welded part 9: Flat part

Claims (2)

  When press-fitting a sleeve to both ends of a deformed tube, a cylindrical part and a conical part having an outer diameter that is obtained by subtracting four times the plate thickness from the inner diameter of the sleeve are used as the pressing metal. Using a shape that is integrally combined, press-fitting the sleeve and deforming the inner surface of both ends of the deformed tube, forming a flat portion from the tube end side, bringing the deformed tube inner surfaces into close contact with each other, and forming the outer surface of the deformed tube into the sleeve A method for sealing a pipe end of a steel pipe expansion type lock bolt, wherein the sleeve and the deformed pipe pipe end are welded to each other at the end after being brought into close contact with the inner surface. The method for sealing a pipe end of a steel pipe expansion type lock bolt according to claim 1 , wherein the deformed pipe is a Zn-based plated steel pipe.

Images