JP3652091B2 - Ductile cast iron pipe for propulsion method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ductile cast iron pipe for a propulsion method, and more particularly to an improvement in a ductile cast iron pipe for a propulsion method.
[0002]
[Prior art]
As a method of burying pipes, there is a propulsion method.
This propulsion method is to push and push the pipe into the ground while sequentially joining the pipes in the pipe direction from the starting pit excavated at the starting point of the pipe, and again after excavating the ground along the pipe and laying the pipe There are very few problems such as construction area, man-hours, noise, etc. compared to the open-cut method of backfilling, and it has the advantage that it is very useful as a pipe laying method in urban areas.
[0003]
By the way, when a pipe is laid by the propulsion method, a strong axial compression force is applied to the pipe body during underground propulsion.
Therefore, the ductile iron pipe used in the propulsion method has a strength structure that can smooth the outer surface as much as possible to reduce the frictional resistance in order to reduce the axial compressive force, and can safely transmit the compressive force generated between the pipes.
[0004]
Conventionally, a ductile cast iron pipe for such a propulsion method has a structure as shown in FIG. 5 or FIG.
That is, in the ductile cast iron pipe for propulsion method shown in FIG. 5, the flange 3 is welded to the rear end 2A of the insertion port 2 of the normal ductile iron pipe 1 and the reinforcing rib 4 is welded. A mortar layer 6 serving as a reinforcing core is provided to smooth the outer surface, and the propulsive force transmission surface is the end surface 7A of the flange 3 and the receiving port 7 that contacts the flange 3.
[0005]
In the figure, 2B denotes a rubber ring that seals between the insertion port 2 and the inner surface of the receiving port 7, and 3A denotes a bolt that fixes the flange 3 to the receiving end surface 7A.
In the ductile cast iron pipe for propulsion method shown in FIG. 6, a cylindrical steel plate 8 is concentrically arranged from the rear end 2A of the insertion port 2 to the opening end 7A of the normal ductile iron tube 1 and mortar 6 is filled therebetween. The outer surface is smoothed, and the propulsive force transmission surface is the inner end surface 7B of the receiving port 7 and the insertion end surface 2C.
[0006]
[Problems to be solved by the invention]
By the way, among the above-mentioned conventional ductile cast iron pipes for the propulsion method, the one shown in FIG. 5 has an external force applied to the anticorrosion layer 9 on the pipe inner surface because the propulsive force transmitting surface is the flange 3 and the receiving end face 7A. In addition, there is no problem of damage to the anticorrosion layer of the pipe due to the implementation of the propulsion method, but the flange 3 and rib 4 must be welded to a sufficient strength, and the manufacturing process such as the reinforcement of the wire mesh 5 is troublesome. However, there was a disadvantage of being expensive.
[0007]
Although the structure shown in FIG. 6 has an advantage that the structure is simple and can be easily manufactured, the propulsive force transmitting surfaces are the insertion end surface 2C and the receiving inner end surface 7B. As a result, the anticorrosion layer at the joint was easily damaged, and there was a drawback that inspection and repair after completion of laying were indispensable.
[0008]
This invention was made for the purpose of solving the above problems, and it is an object of the present invention to provide a ductile cast iron pipe for a propulsion method that is easy to manufacture without fear that the anticorrosion layer is affected by propulsion transmission. It was made as.
[0009]
[Means for Solving the Problems]
In other words, the ductile cast iron pipe for propulsion method according to the present invention has a flange provided at the rear end of the insertion port of the pipe having one end inserted into the insertion port and the other end received the insertion port. An axial rib is provided between the rear face of the mouth at an appropriate interval in the circumferential direction, and an outer surface mortar layer is provided with the axial rib embedded between the rear face of the mouth and the flange. It is what.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described.
FIG. 1 is a fragmentary sectional view of a ductile cast iron pipe for propulsion method according to the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.
[0011]
In FIG. 1 and FIG. 2, a ductile cast iron pipe 11 for a propulsion method has an insertion port 2 at one end and a receiving port 7 for receiving the insertion port 2 at the other end. A flange 3 is provided at the end 2A, and axial ribs 10... 10 are provided between the flange 3 and the rear surface 7C of the receiving port 7 at appropriate intervals in the circumferential direction. The outer surface mortar layer 6 is provided with the axial ribs 10... 10 buried between them.
[0012]
In the above, the axial rib 10 has the same layer thickness as the outer surface mortar layer 6 of the tube 1 as shown in the figure, and also extends only to the surface portion of the outer surface mortar layer 6 as shown in FIG. Moreover, it is good also as a structure extended to the state embedded in the inside of the mortar layer 6, as shown in FIG.
[0013]
In addition, the outer diameter of the flange 3 may be the same as the outer diameter of the receiving port 7 or may be different. In short, the mortar layer 6 fills a smooth surface between the receiving port 7 and the flange 3. It ’s fine.
[0014]
The mortar layer 6 is formed by placing a cylindrical steel plate (not shown) on the outer periphery of the tube 1 to which the flange 3 and the ribs 10... 10 are attached, and pouring mortar between them as an outer mold.
[0015]
In the ductile cast iron pipe 11 for propulsion method according to the present invention, as shown in FIG. .
[0016]
In addition, since the force acting on the flange 3 and the rib 10 is only a compressive force, strict welding is not necessary even when attaching by welding, and welding with a degree to prevent dropping off may be used.
[0017]
【The invention's effect】
As explained above, the ductile cast iron pipe for propulsion method according to the present invention can withstand a high compressive force because the propulsive force is transmitted by the axial rib, and the strength of the pipe itself is increased.
[0018]
During the propulsion method, no force is applied to the anticorrosion layer on the inner surface of the pipe, so that it is not damaged.
Furthermore, when attaching flanges and ribs to the outer surface of the pipe, strict welding work is not necessary, and cylindrical steel sheets that serve as molds for mortar filling can be attached using these flanges and ribs, so mortar work is also possible. It has various effects such as being easy to manufacture and the like.
[Brief description of the drawings]
FIG. 1 is a fragmentary sectional view showing an embodiment of a ductile cast iron pipe for propulsion method according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a fragmentary sectional view showing another embodiment of the propulsion method ductile cast iron pipe according to the present invention.
FIG. 4 is a fragmentary sectional view showing still another embodiment of a ductile cast iron pipe for propulsion method according to the present invention.
FIG. 5 is a cross-sectional view of a main part of a conventional example.
FIG. 6 is a cross-sectional view of a main part of another conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Normal ductile pipe 2 Insert 2A Insert back end 3 Flange 6 Outer surface mortar layer 7 Receptacle 7C Receptacle rear face 10 Axial rib 11 Ductile cast iron pipe for propulsion method

Claims (1)

A flange is provided at the rear end of the insertion tube, one end of which is an insertion opening, and the other end is a reception opening for receiving the insertion opening. A ductile cast iron pipe for a propulsion method, wherein an outer surface mortar layer is provided with an axial rib embedded between the rear face of the receiving port and the flange.

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