JP7534858B2 - Manufacturing method of housing tube - Google Patents

Description

This invention relates to a method for manufacturing housing tubes that are connected by housing joints.

For example, as shown in FIG. 18, initial fire extinguishing equipment is installed in tunnel T of a highway in preparation for a fire inside the tunnel. Such fire extinguishing equipment in tunnel T is composed of fire hydrant devices (emergency equipment) installed at predetermined intervals along the length of the tunnel and connected by water supply piping P. Therefore, when a fire breaks out in tunnel T, the person who discovers the fire can immediately spray water on the fire scene from a nearby fire hydrant to carry out initial fire extinguishing. Ductile cast pipes, steel pipes, plastic pipes, etc. are used for tunnel fire extinguishing water supply piping used for such fire extinguishing (see Patent Documents 1 to 3). In FIG. 18, E is an electrical wiring protection piping.

JP 2001-571 A JP 2011-239851 A JP 2018-91433 A JP 2018-179054 A Japanese Patent Application Publication No. 58-3725

However, although there are some resin pipes with improved heat resistance (see Patent Documents 2 and 3), these heat-resistant resin pipes do not have the same heat resistance as ductile cast pipes and are expensive in terms of cost. Steel pipes have a problem in terms of cost.
In addition, when the fire extinguishing piping structure is constructed at a high place on the inner wall of the tunnel T as shown in FIG. 19, since the top of the inner wall of the tunnel T is arched, the beam F of the crane that lifts the pipe material may interfere with the arched top, making it difficult to directly hang the pipe material down to the piping position. For this reason, as shown in the figure, it is necessary to hang the pipe material down on a temporary support beam G facing the piping position, and then to set it at the piping position by rolling the pipe material or the like. In other words, it is necessary to move it horizontally (arrow in the figure), and it is difficult to adopt an insertion type (spigot type) joint method that requires axial movement of the pipe when connecting the pipe. For this reason, it is often the case that a housing type joint (housing joint) that minimizes axial movement of the pipe when connecting (and removing) the pipe (the pipe end faces are facing or close to each other) is adopted. In FIG. 19, H is a support protruding beam.
The housing joint must have a rib on the outer circumferential surface of the end of the pipe to be connected (see reference numeral 12 in FIG. 17(b) and Patent Document 4). That is, the end faces of the pipes to be connected are butted together (facing each other), the rib is engaged with the housing joint, and the housing joint is used to connect to another pipe via the rib.

By the way, centrifugal casting is less likely to produce defects such as blowholes and shrinkage cavities inside the casting, and the material is finely densified, making it possible to easily and inexpensively produce castings with good quality such as good mechanical properties. For this reason, most of the cast pipes widely used for water pipes and the like are produced by this centrifugal casting method.
In a centrifugal casting machine, as shown in FIG. 20, for example, a cylindrical mold 1 is rotated by rollers 2 while molten metal a is sent into a casting trough 5 via ladles 3 and 4. The molten metal a is cast (poured) through the trough 5 into the rotating mold 1 which moves back and forth, and the molten metal a is uniformly distributed on the inner surface of the mold 1 by centrifugal force, thereby forming a cylindrical molten metal layer (cast pipe) 10' with a uniform pipe thickness.

Conventionally, in centrifugal casting, as shown in the figure, a cast pipe 10' is mainly produced, which has a receiving port 10a at one end and a spigot 10b at the other end that is inserted into the receiving port 10a, and the receiving port 10a is formed into a bulging shape by loading a core 6 into a casting mold 1. For this reason, the cast pipe 10' is demolded by removing the mold band 8, and then, with the core 6 still attached, hooking the claws of a puller on the inner surface of the receiving port 10a and pulling it out of the mold 1.
At this time, if the above-mentioned ridges 12 are formed on the outer peripheral surface of the end portion on the side of the insertion port 10b, the ridges 12 become an obstacle and make it impossible to pull out the mold. In Fig. 20, 7 and 8 are mold bands provided on the ends of the mold 1 to prevent the molten metal a from leaking from those ends.

Incidentally, one method for manufacturing cast pipes with flanges on both ends by centrifugal casting is to produce a straight pipe with a flange on one end by centrifugal casting, and then press a flange into the other end of the straight pipe (see Patent Document 5, claims, figures 1 to 4, etc.).

Under the above circumstances, the objective of this invention is to manufacture a housing tube having protrusions 12 on both ends of a straight tube by centrifugal casting.

One means of the present invention for achieving the above object is a manufacturing method for a housing pipe in which a straight pipe of the same diameter over its entire length has a protrusion on each outer peripheral surface of both ends, and each end is connected to another pipe via the protrusion by a housing joint, the manufacturing method comprising the steps of: producing a straight cast pipe by centrifugal casting; measuring from one end face of the cast pipe and cutting the other end face; forming the other protrusion of the other end face of both ends on the outer periphery of the other end face based on the cut other end face; cutting the one end face by measuring from the cut other end face; forming one protrusion of one end face of both ends on the outer periphery of the one end face based on the cut one end face;
In addition, the two protrusions can be formed by pressing a ring into the end of the cast pipe, or by forming a groove on the outer circumferential surface of the end of the cast pipe and fitting a ring into the groove.

Another aspect of the present invention is a manufacturing method for a housing tube in which a straight tube having the same diameter over its entire length has a protrusion on each outer peripheral surface at both ends, and each end is connected to another tube via the protrusion by a housing joint, the manufacturing method comprising the steps of: producing a cast tube made of a straight tube having a bulge at one end by centrifugal casting; measuring one end face of the cast tube and cutting the other end face; forming the other protrusion of the other end of both ends on the outer peripheral surface of the other end face based on the cut other end face; One end portion is cut by taking measurements from the cut end face of the other end portion, and one of the protrusions of one end portion of both ends is formed on the outer peripheral surface of the one end portion based on the cut end face of the one end portion, and the other protrusion is formed by pressing a ring into the outer peripheral surface of the one end portion and fitting a ring into the groove, and the one protrusion is formed by cutting the bulge portion , or, if the bulge portion is a cast-in protrusion, it is that protrusion.
With this configuration, the protrusion on one end side can be formed by the bulging portion.

In each of the above configurations, the pressed-in ring or the ring fitted into the groove is preferably welded to the outer circumferential surface of the straight pipe.
In addition, if the cast end surfaces at both ends of the cast pipe are clean and do not interfere with the connection of the housing joint, cutting of the ends can be omitted. In this case, cutting of both ends of the cast pipe may be omitted, or either one of them may be omitted.
The housing pipe, which is a straight cast pipe manufactured by the above manufacturing method and has a ridge integrally formed at one end and a ring-shaped ridge formed at the other end, is a new product that has never existed before and is considered to be different from the cast pipe with flanges on both ends described in Patent Document 5. This is because the former is connected by a housing joint, whereas the latter is connected by a flange joint formed by the cast pipe itself.

As this invention is configured as described above, it is possible to inexpensively and smoothly manufacture a housing pipe in which a straight pipe has ribs on the outer peripheral surface at both ends, and each end is connected to another pipe via the ribs using a housing joint.

1A is a front view of a housing tube according to an embodiment of the present invention, and FIG. 1B is an enlarged front view of a partially cut-away portion. FIG. 1 is a diagram showing a manufacturing process of the housing tube according to the embodiment; 11 is a diagram showing another manufacturing process of the housing pipe according to the embodiment; FIG. FIG. 11 is a diagram showing another manufacturing process of the housing pipe according to the embodiment; FIG. 11 is a diagram showing another manufacturing process of the housing pipe according to the embodiment; FIG. 11 is a diagram showing another manufacturing process of the housing pipe according to the embodiment; 5A and 5B are explanatory views of a method for manufacturing the protrusions of the embodiment, in which FIG. 5A is a partial cross-sectional view and FIG. 5A and 5B are another explanatory diagrams for manufacturing the protrusions of the embodiment, in which (a) is a partial cross-sectional view and (b) is a partial perspective view. 5A is a partial cross-sectional view of the protrusion of the embodiment; FIG. 5B is a partial perspective view of the protrusion of the embodiment; FIG. 1 is a schematic diagram showing a manufacturing process of the housing tube; FIG. 11 is a schematic diagram showing another manufacturing process sequence of the housing tube. FIG. 11 is a schematic diagram showing another manufacturing process sequence of the housing tube. FIG. 11 is a schematic diagram showing another manufacturing process sequence of the housing tube. FIG. 11 is a schematic diagram showing another manufacturing process sequence of the housing tube. FIG. 11 is a schematic diagram showing another manufacturing process sequence of the housing tube. FIG. 1 is a partial front view of piping using a housing pipe according to the present invention; 1A is a longitudinal cross-sectional view of a housing joint of the piping, and FIG. 1B is a cross-sectional view taken along line II of FIG. Schematic diagram of fire extinguishing piping in the tunnel Illustration of the fire extinguishing piping installation Schematic diagram of centrifugal casting

As shown in Fig. 1, a housing pipe 10 (hereinafter, ₁₀₁ , ₁₀₂ , ... will be generically designated by the reference symbol "10") according to one embodiment of the present invention has ribs 12, 12 for a housing joint 50 on the outer circumferential surface at both ends of a straight pipe 11 having the same diameter over its entire length. This housing pipe 10 constitutes most of the water supply pipe (hereinafter, simply referred to as "pipe") P of the fire extinguishing piping structure in a tunnel T shown in Fig. 18. The straight pipe (straight section) 11 of this housing pipe 10 is manufactured by centrifugal casting (centrifugal casting) using ductile cast iron.
The housing pipe 10 of this embodiment has, for example, a total length of 5200 mm and an outer diameter of 271.6 mmφ, and a mortar lining 13′ is formed on the inner peripheral surface over the entire length. This mortar lining 13′ is formed after the protrusions 12 are formed.

The housing pipe 10 according to the present invention is manufactured from a cast pipe 10' having a bulging receiving port 10a, which is cast by a centrifugal casting machine shown in FIG.
In one embodiment of the manufacturing method for the housing tube 10, first, a cast tube ₁₀₁ ' (hereinafter, _10'1 , 10'2, ... will be generically referred to as "10'") consisting of a straight tube cast by a centrifugal casting machine as shown in FIG. ₂ (a) is removed from the mold band 8, and the claws of a puller are hooked on the inner surface of the receiving port 10a to pull it out of the mold 1, thereby demolding it (FIG. 2(b)).
Next, the other end (insertion port) end 10b of the cast pipe ₁₀₁ ' is cut off (dashed line _c1 portion) taking measurements from the end face 10a'' of the receiving port (bulge) 10a, and the other rib 12 is formed on the outer periphery of the other end 10b based on the cut other end face 10b'. Then, the one end is cut including the receiving port 10a (dashed line _c2 portion) taking measurements from the cut other end face 10b' to obtain a straight pipe ₁₁₁ of the required length (hereinafter, ₁₁₁ , ₁₁₂ , ... will be collectively referred to as "11"). Then, one rib ₁₂ is formed on the outer periphery of the one end 10a based on the one end face 10a' of the cut straight pipe 111. The ribs 12, 12 on both ends of the housing tube ₁₀₁ are finished symmetrically with respect to the center of the tube axis (center line c), thereby manufacturing the housing tube ₁₀₁ .

The above embodiment is advantageous in terms of cost because it can use a conventional mold 1 as shown in Fig. 20, and as shown in Fig. 3, it is possible to cast a cast pipe ₁₀₂ ' without using a core 6. In this case, the part corresponding to the receiving port 10a becomes thick, and a large amount of molten metal a is wasted. The housing pipe ₁₀₂ is manufactured in the same manner as the above embodiment, as shown in Figs. (b) to (d). At this time, a mold band 8 is also provided on the receiving port (one end) 10a side to prevent leakage of molten metal a from the end face (Fig. (a)).

Another embodiment of the manufacturing method for the housing tube 10 is shown in Fig. 4, in which the ribs 12 are formed by casting. For this centrifugal casting, the mold (metal mold) 1 shown in Fig. 20 may be used, but as shown in Fig. 4(a), the mold 1a may be modified in its receiving port portion, and the sand core 6 may also be modified in its inner periphery 6a. The core 6a is cylindrical with a flange and has grooves 6b for the ribs on its entire inner periphery. By feeding molten metal a into the rotating mold 1a, a cast tube ₁₀₃ ' made of a straight tube is formed, and the molten metal a is caused to flow into the grooves 6b to form the ribs 12 (the ribs 12 are formed by casting).

The cast pipe ₁₀₃ ' shown in Fig. 4(a) is similarly removed from the mold 1a by hooking the claws of a puller on the inner surface of the receiving port 10a (Fig. 4(b)). Measurements are taken from one end 10a of the removed cast pipe ₁₀₃ ', and the other end (insertion port) 10b end is cut (chain line _c1 portion) to form a straight pipe ₁₁₃ (Fig. 4(c)). Using the cut end face 10b' as a reference, the other ribs 12 at both ends of the straight pipe ₁₁₃ are formed on the outer circumferential surface of the other end 10b by the means shown in Figs. 7 and 8 below, and the ribs 12 at both ends 10a, 10b are finished symmetrically with respect to the center of the pipe axis (center line c), to produce a housing pipe ₁₀₃ (Fig. 4(d)). At this time, one end 10a of the straight pipe ₁₁₃ can also be measured from the cut end face 10b' of the other end to obtain the required length of the straight pipe _113. The ridge 12 on one end (one side) can be shaped by cutting with a lathe or the like, as shown in FIG.

Still another embodiment of the method for manufacturing the housing tube 10 is shown in FIG. 5, and in this embodiment, the protrusions 12 are similarly formed by casting. For this centrifugal casting, the mold 1 shown in FIG. 20 may be used, but as shown in FIG. 4(a), a mold (metal mold) 1a is used whose receiving port portion is deformed, and a deformed core 6a is used. The core 6a is cylindrical with a flange and has a groove 6b around its entire inner circumference. By feeding molten metal a into the rotating mold 1a, a cast tube ₁₀₄ ' is formed, and the molten metal a is allowed to enter the groove 6b to form a bulge 12c.

The cast pipe ₁₀₄ ' shown in Figure 5(a) is similarly removed from the mold 1a by hooking the claws of a pulling tool on the inner surface of the receiving port 10a (Figure 5(b)). Measurements are taken from one end 10a of the cast pipe ₁₀₄ ' and the other end (insertion port) 10b end is cut (dashed line _c1 part). Using the cut other end face 10b' as a reference, the other protrusion 12 on both ends of the straight pipe ₁₁₄ is formed on the outer circumferential surface of the other end 10b by the means shown in Figures 7 and 8 described below.
Next, the one end 10a is cut (dashed line _c2 portion) by measuring from the cut other end face 10b' to obtain a straight pipe ₁₁₄ of the required length, and one of the ridges 12 (at both ends) is formed on the outer periphery of the one end 10a based on the one end face 10a' of the cut straight pipe ₁₁₄ , and the ridges 12, 12 at both ends of the straight pipe ₁₁₄ are finished symmetrically with respect to the center of the pipe axis (center line c) to produce the housing pipe _104. The one of the ridges 12 is formed by cutting the bulge 12c (see FIG. 9).

In the embodiment shown in Figures 4 and 5, the flange on the opening side of the core 6a serves to prevent the molten metal a from leaking from the mold band 8, but in the case of a core 6a that does not have the flange and in which the molten metal a reaches the opening of the mold 1a, the molten metal leakage is prevented by the mold band 8, as in the embodiment of Figures 2 and 3. In this case, the cast pipes ₁₀₃ ', ₁₀₄ ' are demolded by removing the mold band 8, and thereafter the housing pipes ₁₀₃ , ₁₀₄ are produced by the same action.

Yet another embodiment of the manufacturing method for the housing tube 10 is shown in Figure 6, and this embodiment is a cast tube ₁₀₅ ' consisting of a straight tube of the same diameter over its entire length, without any bulging portions 12c at either end, and a casting mold 1b having a cylindrical cavity over its entire length without any bulging receiving portion, as shown in Figure 6(a).
Using this mold 1b, a cast pipe ₁₀₅ ' cast by a centrifugal casting machine as shown in Fig. 6(a) is demolded (Fig. 6(b)), the other end (insertion port) end 10b of the cast pipe ₁₀₅ ' is cut (dashed line _c1 ), and a measurement is taken from the cut other end face 10b' to cut the one end (dashed line _c2 ) to form a straight pipe ₁₁₅ (Fig. 6(c)). Similarly, the cast pipe ₁₀₅ ' is demolded by hooking a claw of a pull fitting having a claw on the inner surface of the straight pipe and pulling it out.
The straight pipe ₁₁₅ has both ends on their outer peripheries formed with ridges 12, 12 based on the cut end faces 10a', 10b', and the outer periphery ridges 12, 12 at both ends of the straight pipe ₁₁₅ are finished symmetrically with respect to the center of the pipe axis (center line c) by the means shown in Figures 7 and 8 below to produce the housing pipe _105. At this time, the other end 10b of the straight pipe ₁₀₅ ' may be cut, and then the ridges 12 may be formed on the outer periphery of the other end based on the cut other end face 10b', and then the one end 10a may be cut by measuring from the other end face 10b', and the ridges 12 may be formed on the outer periphery of the one end 10a based on the cut end face.

In manufacturing the housing pipes ₁₀₃ , ₁₀₄ , and ₁₀₅ of each of the above embodiments, if the cast end surfaces of both ends 10a, 10b of the cast pipe 10' (straight pipe 11) are clean and do not need to be cut, the straight pipe 11 can be made to the required length without performing the above-mentioned cuts _c1 and _c2 .

The above-mentioned ridges 12 are formed by the means shown in Figures 7 to 9. The means shown in Figure 7 involves forming a groove 13 around the entire outer periphery of the end of the straight pipe 11 (cast pipe 10'), fitting a ring 12a with a portion of its circumference missing into the groove 13, and welding 14 around the entire front and rear circumferences. This means can be used to form the ridges 12 on the other end and the ridges 12 on one end of a straight pipe that do not have a bulge 12c.

The method shown in Figure 8 is to fit the ring 12b into the end of the straight pipe 11 and weld it 14 without forming a groove 13. In this case, the ring 12b may be a partially notched ring 12a as shown in Figure 7(b), or a circular object 12b without a notch and continuous around the entire circumference as shown in Figure 8(b) (see Figure 8(b)). In this case, the ring 12b is attached to the end of the straight pipe 11 by press fitting. In these cases, welding 14 is performed on the entire front and rear circumferences of the rings 12a and 12b. This method can be used to form a protrusion 12 on the other end side or a protrusion 12 on one end side that does not have a bulge 12c.

The method shown in Figure 9 is for forming the protrusion 12 or bulge 12c at one end by centrifugal casting at the same time as the straight pipe 11 is manufactured, and the protrusion 12 at the other end is formed by the method shown in Figures 7 and 8. In the case of the bulge 12c, the protrusion 12 is formed from the bulge 12c by cutting with a lathe or the like, as shown in Figure (a), and even in the case of the protrusion 12 that is cast as is, it can be cut to shape as necessary. This method is not used for the protrusion 12 on the other end, but can be used to form the protrusion 12 when the protrusion 12 is cast or has a bulge 12c on one end.

In either case, the rings 12a and 12b can be made of general structural rolled steel (SS material), but any material that can be used for the protrusions 12, such as ductile cast iron, can be used, and the protrusions 12 can be zinc-sprayed or otherwise treated to prevent corrosion.

The order of forming the ribs 12 on the straight pipe 11 (10') may be appropriately considered, for example, as shown in Figs.
10 shows a case where the protrusions 12 of the housing pipes 10 ₁ and 10 2 (hereinafter referred to as 10) shown in FIG. 2 and FIG. 3 are formed by pressing in the rings 12a and _12b in a factory equipped with a cutting machine A, a press-fitting machine B, a welding machine C, and a lathe (cutting machine) D in the same line, and the cast pipe 10' (10 ₁ ', 10 ₂ ') that has been demolded is first fed into the cutting machine A to cut off the other end (insertion port) 10b, and then the cast pipe 10' is fed into the press-fitting machine B to fit the rings 12a and 12b onto the outer circumferential surface of the other end 10b. The cast pipe 10' is then fed into the welding machine C to perform welding 14, and then fed into the lathe D to shape the protrusions 12.
Furthermore, the cast pipe 10' with the ribs 12 formed thereon is inverted and fed again into the cutting machine A to cut off one end (receiving port) 10a, and rings 12a, 12b are fitted onto the outer periphery of one end 10a of the cast pipe 10'. The cast pipe 10' is then fed into a welding machine C to perform welding 14, and then fed into a lathe D to adjust the shape of the ribs 12, thereby obtaining the housing pipe 10.
In the drawing, the reference character e denotes a rail provided along the line of each processing machine A, B, C, and D, and a carriage carrying a cast pipe 10' (11) runs on the rail e via rolling wheels. Although the rails e are shown separated vertically in the drawing, they are continuous on the same line, and the rails e corresponding to each processing machine are in the same position (on the same line).

In this manner, when the cast pipe 10' is reversed after the other protrusion 12 is formed, if the cutting machine A and the protrusion forming machines B, C, D are fixed and the working directions (positions) of cutting and forming are fixed, the reversal results in cutting and forming in the same direction as the other protrusion 12, so there is no need to provide two (or more) cutting machines or protrusion forming machines with different working directions (positions).
The reversal is performed by using a forklift or the like, for example by temporarily placing the cast pipe 10' from the rail e onto another position (another rail), and then picking it up from the other side and returning it to the previous line (the cart on the rail e).

The embodiment shown in FIG. 11 is a case where the protrusions 12 of the housing tubes ₁₀₁ , ₁₀₂ shown in FIG. 2 and FIG. 3 are formed by forming a groove 13 and fitting a ring 12a into the groove 13 in a factory equipped with a cutting machine A, a welding machine C, and a lathe (cutting machine) D in that order along the same line.
First, the cast pipe 10' that has been demolded is sent to a cutting machine A to cut off the other end (insertion port) 10b, and then the cast pipe 10' is sent to a lathe D to form a groove 13 on the outer circumferential surface of the other end and fit a ring 12a into the groove 13. The ring 12a can be fitted manually, but a suitable fitting machine is also used (the same applies below).
Thereafter, the cast pipe 10' is turned back and forth in its length direction, and then fed into a cutting machine A to cut one end (socket, flange) 10a, which is then fed into a lathe D to form a groove 13 and fit a ring 12a into the groove 13. The straight pipe 11 with the ring 12a fitted therein is then fed into a welding machine C to weld 14 around the ring 12a, and further fed into the lathe D to cut the ring 12a and weld 14 and form one of the protrusions 12. The straight pipe 11 is then turned back and forth in its length direction, fed into the welding machine C to weld 14 around the other ring 12a, and then fed into the lathe D to cut the ring 12a and weld 14 and form the other protrusion 12, thereby obtaining the housing pipe 10.

The embodiment shown in FIG. 12 is a case where the other protrusion 12 of the housing tube ₁₀₃ in FIG. 4 is formed by pressing a ring 12b in a factory equipped with a cutting machine A, a press-fitting machine B, a welding machine C, and a lathe (cutting machine) D in sequence along the same line.
First, the cast pipe ₁₀₃ ' that has been demolded is sent to a cutting machine A to cut off the other end (insertion port) portion 10b, and then the cast pipe 10' (11) is sent to a press-fitting machine B to fit a ring 12b onto the outer periphery of the other end 10b. After that, the straight pipe 11 is sent to a welding machine C to perform welding 14, and then sent to a lathe D to shape the protrusion 12.
Next, the straight pipe 11 with the protrusion 12 formed thereon is inverted and fed back into the lathe D, where the cast-in protrusion 12 on the outer peripheral surface of one end (receiving port) 10a is cut to obtain the housing pipe 10 with the protrusion 12 at one end shaped.
In this embodiment, when forming one of the protrusions 12 of the housing pipe in FIG. 5, after the housing pipe is turned over, the bulging portion 12c is cut in the cast protrusion processing to form the protrusion 12 at one end.

In each of the above methods, the straight pipe 11 (cast pipe 10') is reversed during the formation of the ribs 12, so the cutting machine A and the rib forming machines B, C, and D are fixed and the direction of the cutting and forming work is fixed. However, if the reversal is not performed, as in Figure 13 for Figure 10, Figure 14 for Figure 11, and Figure 15 for Figure 12, multiple cutting machines A and rib forming machines B, C, and D can be installed on the same line and both ends can be cut by each cutting machine, etc.

The protrusions 12 can be formed by "fitting the ring 12a into the groove 13 (ring fitting)" as shown in Fig. 7, "pressing the ring 12b (ring press fitting)" as shown in Fig. 8, and "cutting the cast-in protrusion 12 or the bulge 12c (cast-in cutting)" as shown in Fig. 9. Therefore, the forming modes of Figs. 10 to 15 are appropriately changed depending on the means for forming the protrusions. For example, when forming the protrusions 12 of the housing tube ₁₀₄ in Fig. 5, after inversion in the mode shown in Fig. 12, the bulge 12c is cut in the cast-in protrusion processing to form the protrusion 12 at one end.
In addition, in the embodiment shown in Figure 12, when housing pipes ₁₀₃ , ₁₀₄ are manufactured from cast pipes ₁₀₃ ', 104' shown in Figures 4 and ₅ , the other end 10b is cut off by a cutting machine A, a groove 13 is formed by a lathe D, a ring 12a is fitted into the groove 13 by a pressing machine B, and after inversion, cast protrusion processing is performed by the lathe D, and housing pipes ₁₀₃ , ₁₀₄ having protrusions 12 at both ends are manufactured by "fitting the ring 12a into the groove 13" and "cast cutting processing".
Furthermore, since either "ring fitting" or "ring press fitting" can be used to form the ridges 12 on the straight pipes ₁₁₁ , ₁₁₂ , ₁₁₅ of the housing pipes ₁₀₁ , ₁₀₂ , ₁₀₅ in Figures 2, 3, and 6, three combinations of "ring fitting" and "ring press fitting", "ring fitting" and "ring fitting", and "ring press fitting" and "ring press fitting" are possible, and the positions and work procedures of the cutting machine A, press fitting machine B, welding machine C, and lathe (cutting machine) D are appropriately changed accordingly. For example, when forming the ridges 12 on the housing pipe ₁₀₅ in Figure 6, for example, "ring press fitting" and "ring press fitting" can be performed in the manner shown in Figure 10, and "ring fitting" and "ring fitting" can be performed in the manner shown in Figure 11.

The housing pipe 10 shown in FIG. 1 is manufactured by the above-mentioned means, and next, the work procedure for constructing a piping P at a high point on the inner wall of a tunnel T, as shown in FIG. 18, using this housing pipe 10 will be described.
First, as shown in Fig. 19, the housing pipe 10 is hung down next to the piping position, and then the housing pipe 10 is held horizontally by rolling or the like and set at the piping position. After the set straight pipes 10 are centered, they are connected watertightly with the housing joint 50 as shown in Figs.

As shown in FIG. 17, the housing joint 50 is composed of half annular couplings 51, 51, bolts and nuts 52 that fasten the pair of half couplings 51 at both ends, and a rubber ring 53. The opposing ends of the pair of half couplings 51 are provided with L-shaped fastening fittings 54, and as shown in the figure, the pair of half couplings 51 are fitted to the ends of the opposing straight pipes 10, 10 with the rubber rings 53 interposed between them so as to sandwich both protrusions 12, and the fastening fittings 54 are fastened with bolts and nuts 52 to connect the two straight pipes 10, 10 in a watertight manner. At this time, lubricating oil is applied to the contact surface (contact surface) of the pipe end with the rubber ring 53, and silicone grease or high viscosity silicone oil is used as the lubricating oil.

When multiple housing pipes 10 are connected in series and the location of the emergency equipment (fire hydrant) is reached, a T-shaped branch pipe (T-pipe) 40 having protrusions 12 on both ends is set at that position, as shown in Figure 18, and one end of it is connected to the housing pipe 10 with a housing joint 50. Between the T-shaped branch pipe 40 and the housing pipe 10 that was previously connected, the housing pipe 10 etc. are cut, and a second-cut short pipe 20 having a protrusion 12 at one end and a first-cut short pipe 30 having a K-shaped socket at one end and a protrusion 12 at the other end are connected to create an integrated pipe material, which is then positioned and connected between the housing pipe 10 and the T-shaped branch pipe 40.
At this time, even if the integrated pipe material of the B-cut short pipe 20 and the A-cut short pipe 30 does not fit snugly between the pipe 10 and the T-shaped branch pipe 40, the K-shaped joint and housing joint 50 between the B-cut short pipe 20 and the A-cut short pipe 30 have an axial movement tolerance of 8 + 20 mm, so there is a margin of error in construction precision, and the degree to which the insertion port of the B-cut short pipe 20 is inserted into the receiving port of the A-cut short pipe 30 can be adjusted to ensure that the integrated pipe material of the B-cut short pipe 20 and the A-cut short pipe 30 fit securely between the straight pipe 10 and the T-shaped branch pipe 40 and connected.

From the T-shaped branch pipe 40 onwards, the housing pipe 10 is connected in the same manner as described above, and the T-shaped branch pipe 40 is positioned at the location of the fire hydrant device, and a pipe material connected to the B-cut short pipe 20 and A-cut short pipe 30 is positioned and connected between the straight pipe 10 and the T-shaped branch pipe 40.
In this embodiment, the B-side short pipe 20 and the A-side short pipe 30 are connected after the T-shaped branch pipe 40 is arranged, but they can also be connected in the order of the B-side short pipe 20, the A-side short pipe 30, the T-shaped branch pipe 40, the straight pipe 10, etc. In this case, the piping length can be adjusted by adjusting the insertion of the insertion port 21 of the K-shaped joint of the B-side short pipe 20 and the A-side short pipe 30.
In addition, in each of the above embodiments, one end is the "receiving port" and the other end is the "insertion port," but it goes without saying that one end can be the "insertion port" and the other end can be the "receiving port" as long as it does not interfere with cutting or forming the protrusions.

In the above embodiment, the pipe material for the housing pipe 10 and the like is a ductile cast pipe. However, it goes without saying that the present invention can be applied to any material that can be centrifugal cast, such as grey cast iron.
Thus, the present invention should be considered to be illustrative and not restrictive in all respects, and the scope of the present invention is defined by the claims, and it is intended to include all modifications within the scope and meaning equivalent to the claims.

P Water supply pipe 1, 1a, 1b Mold (metal mold, mold)
₁₀ , 101, ₁₀₂ , ₁₀₃ , ₁₀₄ , ₁₀₅ Housing pipe 10', ₁₀₁ ', ₁₀₂ ', ₁₀₃ ', ₁₀₄ ', ₁₀₅ ' Cast pipe 10a One end of housing pipe (socket)
10b Other end (insertion port)
11, _{11 1} , 11 ₂ , 11 ₃ , 11 ₄ 11 ₅ Straight pipe (straight part)
12: protrusions 12a, 12b: protrusion ring 13: groove 14: welding 50: housing joint

Claims (3)

A method for manufacturing a housing pipe (10 1 , 10 2 , 10 5 ) in which a straight pipe (11) having the same diameter over its entire length has ribs (12, 12) on the outer peripheral surfaces of both ends (10 a, 10 b), and each end (10 _a , 10 _b ) is connected to another pipe via the ribs (12) by engaging the ribs (12, ₁₂ ) with a housing joint (50), comprising:
A cast pipe (10 ₁ ', 10 ₂ ', 10 ₅ ') consisting of a straight pipe is produced by centrifugal casting, a measurement is taken from one end face (10a'') of the cast pipe (10') and the other end face (10b) is cut off, and a protrusion (12) for the other end (10b) of both ends (10a, 10b) is formed on the outer circumferential surface of the other end face (10b) based on the cut other end face (10b'), one end face (10a ) of the cast pipe (10') is cut off, and a protrusion (12) for one end (10a) of both ends (10a, 10b) is formed on the outer circumferential surface of the one end face (10a) based on the cut one end face (10a'),
and forming a groove (13) on the outer peripheral surface of the end portion of the cast pipe (10') and fitting a ring (12a, 12b) into the groove (13), the two protrusions (12, 12) are formed in the end portion of the cast pipe (10') by pressing a ring (12a, 12b) into the groove (13). A method for manufacturing a housing pipe (103, 104) in which a straight pipe (11) having the same diameter over its entire length has ribs (12, 12) on the outer peripheral surfaces of both ends (10a, 10b), and each end ( _10a , _10b ) is connected to another pipe via the ribs (12) by engaging the ribs (12, 12) with a housing joint (50), comprising:
A cast pipe ( ₁₀₃ ', ₁₀₄ ') consisting of a straight pipe having a bulge (12c) at one end (10a) is produced by centrifugal casting, a measurement is taken from one end face (10a'') of the cast pipe (10') and the other end (10b) is cut, and the other protrusion (12) of the other end (10b) of both ends (10a, 10b) is formed on the outer circumferential surface of the other end (10b) based on the cut other end face (10b'), the one end (10a) is cut by taking a measurement from the cut other end face (10b'), and one protrusion (12) of one end (10a) of both ends (10a, 10b) is formed on the outer circumferential surface of the one end (10a) based on the cut one end face (10a'),
and the other protrusion (12) is formed by pressing a ring (12a, 12b) into the housing pipe, or by forming a groove (13) on the outer circumferential surface of one end portion and fitting a ring (12a, 12b) into the groove (13), and the one protrusion (12) is formed by cutting the bulge (12c) , or, if the bulge is a cast protrusion, the one protrusion is formed by cutting the bulge (12c). The method for manufacturing a housing tube according to claim 1 or 2, wherein the pressed-in rings (12a, 12b) or the ring (12a) fitted into the groove (13) are welded to the outer circumferential surface of the cast tube (10').

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