JPH01186111A - Method of construction piping for buried cable protective steel tube - Google Patents

Abstract

PURPOSE:To easily bend a pipe in an arbitrary direction in a groove at a site to be piped by bending a cable protective steel tube through a pipe securing frame by rotating a threaded shaft. CONSTITUTION:When a cable protective steel tube 7 is bent, a pipe securing frame 1 is first inserted to the tube 7 over a position to be desirably bent, and a threaded shaft 4 is rotated clockwise by a turning tool. Then, bearing fittings 2 is retained at the same position, and bearing fittings 3 are moved in a direction toward the fittings 2 on a shaft 4 in response to the rotating motion of the shaft 4. As a result, a tensile strength is generated at the shaft 4, a bending moment is applied to the tube 7 through the frame 1 to be bent. When the shaft 4 is rotated counterclockwise, the fittings 2 are retained at the same position, and the fittings 3 are moved in a direction from the fittings 2 on the shaft 4 in response to the rotating motion of the shaft 4. As a result, a compression force is generated at the shaft 4, a bending moment is applied to the tube 7 through the frame 1 to be able to be bent.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention allows flexible cable protection steel pipes to be installed easily on site, for example, in cable protection steel piping work when burying power or communication cables, etc. Bending process 1
1, but it is related to a construction method that performs piping installation.

(Prior art) Conventionally, in the piping work of the bent part of the buried base, for example, the pipe bender shown in Fig. 6 of the pipe bending process described in 178 to 179 Q of the pipe of the Steel Handbook ■ has been used. A method of bending the pipe by placing it near the construction site, or a method of using a pipe pre-bent at a factory, or a method of using a flexible pipe assembled at a factory as described in the actual opening/closing 60-54884 s bulletin shown in the 71st leap. The method used was the method shown in Figure 8, or the method of assembling flexible row steel pipes at the piping site. In addition, as a manufacturing method for bent pipes for ducts, JP-A-59
There is a method described in Publication No.-2182:1. 61″A
8 in the middle is a pipe, 9 is an internal bending mold, IO is a tightening tool, 11 is a rotating press mold, 12 in Fig. 7 is a rubber gasket, 13
14 is a pipe, 14 is a caulked joint, 15 in FIG. 8 is a 4-section steel pipe, and 15 is a fan-shaped joint.

(Problem to be solved by the invention) Pipe bending is usually performed using a pipe bender or the like. It is impossible to perform bending in various directions at a distance of approximately 2 to 1.8 m.

Therefore, in order to form the pipe to the current dimension of 0, it is necessary to perform several machining operations due to several dimensional corrections, which significantly impairs work efficiency. As a result, depending on the inner diameter size or direction, the inner diameter becomes smaller than the original pipe diameter, which may hinder wiring work. In addition, as shown in Figure 7, flexible pipes assembled in a factory require many rubber seals to ensure airtightness at the connections between universal joints, making it almost difficult to ensure stable airtightness at all times in a buried environment. be. Furthermore, the method of on-site assembly of flexible M-shaped steel pipes shown in FIG. 8 cannot be expected to ensure airtightness, as is clear from its mechanism, and requires a lot of work because it must be constructed on-site after the keitz is laid.

From the following, the present invention improves the workability and airtightness of on-site piping.
; It provides a new construction method that can be used.

(Means for Solving Problem 1) The piping construction method for a buried cable protection steel pipe of the present invention solves these problems as follows. The gist is that the outer diameter is 60~217mm-5, the wall thickness T is t, and S~5.01-
So, the mountain height H in the tube axis direction? : 15 to 35-, a flexible cable protection steel pipe with a pitch P of 20 to IiO+sm corrugation 1' applied continuously or intermittently, and a width corresponding to the diameter of the valley of the cable protection steel pipe. A pair of fork-shaped pipe fixing frames with one end open at the other end are connected with a threaded shaft at the other end. After inserting and fixing the tool into the cable protection steel pipe, threading is performed. A piping construction method for a buried cable protection steel pipe, characterized in that the cable protection steel pipe is bent through a pipe fixing frame by rotating a fixed shaft, and the bending process can be easily performed within a narrow groove at a piping construction site. However, since piping construction is carried out in circular motions, highly efficient piping construction work has been realized for the first time, and since the structure of this steel pipe is a single piece, it is also effective in ensuring airtightness.

(Function) The present invention dramatically improves the flexibility of steel pipes in order to facilitate bending of buried cable protection steel pipes at piping construction sites, as shown in Figs. 1(a) and (b). Then, the pipe is partially expanded by bulge processing in the radial direction, and corrugated processing is applied continuously or intermittently in the axial direction of the pipe. The flexibility of this corrugated cable protection steel pipe varies greatly depending on the pipe diameter, wall thickness, wave shape, etc.
On the other hand, the diameter of a pipe is determined by the thickness of the cable wired inside. Therefore, we investigated the wall thickness and corrugated shape of the steel pipe that satisfies its function as a cable protection pipe and turns the bent part using a simple bending tool. First, bending tests were performed on a corrugated flexible tube and a normal straight tube. As is clear from the second UA, the bending load of the cable protection steel pipe, which is more flexible compared to the straight pipe, is significantly reduced. In addition, the thinner the wall, the smaller the bending load, which increases the flexibility and eases bending. If it is secured properly, there will be no major impact. From this, it was found that bending workability could be ensured using a corrugated steel pipe with a comparatively balanced wall thickness. In addition, after the cable protection pipe is buried, a large pressure is applied to the outside surface of the pipe due to the upper pressure and the external pressure from A comparison was made between the pipe and an ordinary straight pipe. As is clear from No. 31'A, the flat 4J weight of the flexible cable protection steel pipe is significantly increased compared to the straight pipe, and it has superior properties in terms of strength. Furthermore, if the wall thickness increases, the bias +L load will become smaller, or the conventional if! It can be seen that it has sufficient strength when compared to the f-tube.

From the above, b (the wall thickness of flexible cable protection steel pipes varies depending on the bending method, but assuming that the work is done with a simple bending tool in the pipe construction groove, the maximum bending load shown in Figure 2 is approximately 2000 kgf) Therefore, the maximum wall thickness is 5IIIl.Also, the minimum wall thickness is about 1.5 mm considering the corrosion allowance in the piping design, but it is possible to use materials with galvanized inner and outer surfaces, polyethylene, etc. to improve corrosion resistance. It is effective to apply a resin coating.Alternatively, using stainless steel has good corrosion resistance.

On the other hand, the pitch and peak height of the wavy shape are determined as follows. When using flexible cable protection steel pipes, if the pitch is too small, the ridges will deform during bending, the pitch will get caught on the compression side, making it difficult to set the bending IJL, or the ridges will interfere, resulting in poor processing, and the minimum value is 20 mm. It will be about. Also, if the pitch is too large, the bending radius will be large and the pitch will be too large.
The maximum length is about 60mm. Also, if the mountain height is too large, the burial space will increase, so the maximum burial space will be about 35 layers. If the mountain height is too low, the bending load will increase and easy bending cannot be used, so the minimum value is 15 mm.
It will be about.

Therefore, in order to solve the problem described in 1γj, the flexible cable protection steel pipe has the following dimensions.

Target pipe diameter (D): 60-217mm plate
Thickness (T): L, S ~5. OI Bi・Sochi
(P): 20 ~ 60 鳳■ Mountain height (H):
15-35 Emperor's Festival Bi-Sochi (W): 10
0 ~ 500 - Number of waves per 100 threads = 3 ~ Continuous or Flr in corrugation processing in the direction of the tube axis
The major difference between continuous bending is the bending radius.
The former is used for a small bending radius range of 3DR or more, and the latter is used for a large bending radius range of 7DR or more.

Figure 4 shows the structure of an example of an on-site bending tool that facilitates bending in pipe buried trenches.L is a pair of vibe fixing frames, one end of which is open with a width corresponding to the diameter of the trough of the flexible pipe. It has a fork shape and is fixed onto the flexible tube by simply inserting it into the tube. Therefore, the bending tool can be easily set at the desired bending point, and work can be performed in narrow spaces.

At the other end, a pair of vibe fixing frames 1 are connected by a machined shaft 4 to which each bearing is attached with a metal fitting 2.3. Reference numeral 2 denotes a bearing having bearings 2a at both ends, so that even when the threaded shaft 4 rotates, it remains in the same position on the threaded shaft 4 in contact with the bearing, and prevents the rotational movement of the threaded shaft 4. The bearing is a metal fitting and has a reaction force receiver 2b to receive the reaction force when rotating the shaft 4 which is threaded using a rotary tool. Reference numeral 3 denotes a bearing with a female thread and a threaded shaft 4. The bearing is a metal fitting and is structured to move on the threaded shaft 4 in response to rotational motion. Reference numeral 4 denotes a shaft with a male thread, and one end 4a has a structure that can be rotated with a rotary tool. Reference numeral 5 refers to the bearings that connect the metal fittings 2 and 3 to the vibrator fixing frame 1. The mounting holes for the bearings are made into elongated holes to facilitate the setting of the fixing frame 1. The bearing 6 has a pin structure that rotates as the metal fitting 2.3 progresses as the bending process progresses.

As shown in No. 51''A(a), for example, when performing bending using the tool of the present invention, insert the vibrator fixing frame l into the flexible tube 7 across the point to be bent, and as shown in FIG. 5(b). As shown in the figure, when the threaded shaft 4 is rotated clockwise with a rotary tool, the bearing and the metal fitting 2 remain in the same position, and the bearing becomes the threaded shaft according to the rotation of the threaded shaft 4. 4": The bearing moves in the direction approaching the metal fitting 2 side. As a result, a tensile force is generated on the threaded shaft 4 and
(How is the bending moment applied to the tube 7 for internal bending [1
It becomes 1. Further, as shown in Fig. 5(C), when the threaded shaft 4 is turned counterclockwise, the bearing and the metal fitting 2 remain in the same position, and the bearing and the metal fitting 3 rotate according to the rotational delay effect of the threaded shaft 4. The bearing moves the threaded shaft 4h in a direction away from the metal fitting 2. As a result, a compressive force is generated on the twisted shaft 4, and a bending moment is applied to the flexible tube 7 via the vibrator fixing frame 1, resulting in an outward bending process.

Furthermore, if the spacing between the other ends of the pair of pipe fixing frames l is reduced or expanded in the same way as the shaft 4, which is threaded using a hydraulic jack, etc., the spacing of the pipe fixing frames l will be restricted, and the amount of right-handed movement will be limited. Due to the narrowness and direction of movement, installation of the hydraulic jack makes it difficult to change the position and increase the weight of tools, which also impairs the bending position and its workability. Therefore, by using the tool of the present invention, bending or shouldering can be performed in any direction in a narrow working space.

(Example) The steel type is STKM11 carbon steel pipe for mechanical structure according to JIS standard.
A, Pipe outer diameter is 139.8-1 wall thickness 2.8-■, corrugated bi-edge 351-cm, peak height Z5-0, number of ridges ZO-mounted flexible cable protection steel pipe Figure 4 Using the on-site flexible pipe bending tool shown in the figure, the width of the pipe construction site is 0.8 m and the depth is 1.
．． As a result of performing internal bending and external bending at a bending angle of 90 degrees in an 8 m trench, pipe construction work was carried out advantageously while performing bending with a bending radius of 4 DR (approximately 550 l).

(Effect of emitting l) - By applying the workability of the present invention to the piping site work when burying the vine, it becomes possible to easily bend the pipe in any direction in the groove at the piping construction site, and the piping construction work becomes easier. and has a great effect on work efficiency. Furthermore, the J# structure of this steel pipe is an integral shape, which has an excellent effect on ensuring airtightness.

[Brief explanation of the drawing]

Figure 11:ill (a) and (b) are front views of the cross section of the flexible tube in the present invention, Figure 2 is a graph showing the bending test results, Figure 3 is a graph showing the flattening test results, Figure 4 ( a) and (b) are front and side views of examples of on-site flexible bending tools, Figures 5 (a), (b), and (c) are front views explaining the situation during bending, and No. 61M is a conventional technique. Figure 7 is a perspective view of the pipe bender, Figure 7 is a front view of the flexible pipe, Figure 8 is a front view of the flexible pipe.
The figure is a front view of the flexible side steel pipe. 1... Pipe fixing frame 2... Bearing is metal fitting 2a.
...Bearing 2b...Reaction force receiver 3...The movable bearing is a metal fitting 4...Threaded shaft 4a...
Rotation addition position 5...Connection fitting 6...Connection bottle 7...Flexible tube 8...Pipe
9...Fixed bending mold lO...Tightening tool 1
1...Rotary press mold 12...Rubber gasket 13
... Pipe 14 ... Caulked joint 15 - ... Split steel pipe 16 - ... Split joint Fig. 1 (Q) Fig. 2 Fig. 3 Plate thickness Fig. 7 Fig. 8 1°, 31. ．． 2.7 yaa

Claims (1)

[Claims] Outer diameter D is 60-217mm, wall thickness T is 1.5-5.0m
m, the mountain height H in the tube axis direction is 15 to 35 mm, and the pitch P
It has a flexible cable protection steel pipe that has been continuously or intermittently corrugated to a length of 20 to 60 mm, and a fork shape with one end open at a width corresponding to the diameter of the valley of the cable protection steel pipe. A pair of pipe fixing frames are connected at the other end by a threaded shaft, and the tool is inserted and fixed into the cable protection steel pipe, and then the threaded shaft is rotated to connect the tool to the cable protection steel pipe through the pipe fixing frame. A piping construction method for a buried cable protection steel pipe, the method comprising bending the cable protection steel pipe.