JP7519794B2 - 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. 14, 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. 14, E is an electrical wiring protection piping.

JP 2001-571 A JP 2011-239851 A JP 2018-91433 A JP 2018-179054 A

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. 15, 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. 15, H is a support protruding beam.
The housing joint needs to have a rib on the outer circumferential surface of the end of the pipe to be connected (see reference numeral 12 in FIG. 13(b) and Patent Document 4). That is, the end faces of both pipes to be connected are opposed to each other, the rib 12 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. 16, 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 an insertion port 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 the 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 the drawing, 7 and 8 are mold (casting) bands provided on the ends of the mold 1 to prevent the molten metal a from leaking from those ends.

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 of the means for achieving the above object of the present invention is a manufacturing method for a housing tube in which a straight tube of the same diameter over its entire length has a rib on the outer periphery of each end, and each end is connected to another tube via the rib by a housing joint. The method adopts a configuration in which measurements are taken from one end face of a cast tube made of a straight tube produced by centrifugal casting, the other end face is cut, and the other end side rib is formed on the outer periphery of the other end side using the cut end face as a reference, and then the cast tube is reversed in the longitudinal direction, and one end side is cut by taking measurements from the cut end face of the other end, and the one end side rib is formed using the cut end face as a reference.

In this way, if the cast pipe is inverted after the other (end) protrusion is formed, and the cutting machine and protrusion forming machine are fixed and the working direction of cutting and forming is fixed, when forming the protrusion on one end side, the reversal results in cutting and forming in the same direction as the other protrusion, so there is no need to provide multiple cutting machines and protrusion forming machines with different working directions.

In this configuration, the straight pipe to be centrifugally cast has a bulge at one end thereof, and measurements are taken from the cut end face of the other end, and the one end is cut including the bulge, and the protrusion on the one end can be formed based on the cut end face.
Furthermore, in the case where the cast pipe produced by centrifugally casting has a bulge at one end thereof, the protrusion at that end can be formed by cutting the bulge.
Furthermore, the formation of each of the above-mentioned ridges can be achieved by forming a groove around the entire circumference of the outer circumferential surface of the end of the cast pipe (straight pipe) and fitting a ring into the groove, or by fitting a ring directly (without forming a groove) onto the outer circumferential surface of the end of the straight pipe. In this case, the ring can be welded to the outer circumferential surface of the cast pipe.

In the manufacturing methods for each of the above configurations, 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 those ends can be omitted. In this case, cutting of both ends of the cast pipe may be omitted, or either one may be omitted. If cutting of the end is omitted, the ridges can be formed based on that end, or the end can be measured, cut, and then the ridges can be formed based on the cut end surface. In this case, it is necessary to increase the casting precision to ensure the length of the housing pipe and the position of the ridges are accurate.

The protrusion on the one end side can be formed by pressing a ring into the end portion, by forming a groove on the outer circumferential surface of the one end side and fitting a ring into the groove and welding it, or by forming a bulge on the one end side and cutting the bulge.
The protrusion on the other end can be formed by pressing a ring into the other end, or by forming a groove on the outer circumferential surface of the other end and fitting a ring into the groove and welding it.
In the manufacturing methods for each of the above configurations, measurements are taken to obtain a housing tube of the required length, and the protrusions are formed based on the cut end face so that when the end face of the connecting tube is opposed, the protrusions will be in the required position from the opposing face to enable smooth connection by the housing joint.

As this invention is configured as described above, it is possible to inexpensively and smoothly manufacture a housing tube that has ridges on the outer peripheral surface of each end and connects each end to another tube via the ridges 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; 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. 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. 14. 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.

In one embodiment of the manufacturing method of the housing pipe 10, a cast pipe ₁₀₁ ' shown in FIG. 2(a) (hereinafter, _10'1 , _10'2 , ... will be generically referred to as "10'") cast by a centrifugal casting machine shown in FIG. 16 is demolded (FIG. 16(b)), a measurement is taken from an end face (one end face) 10a'' of the receiving port 10a of the cast pipe ₁₀₁ ' and the other end (insertion port) end 10b is cut (dashed line _c1 portion), the other protrusion 12 is formed on the outer periphery of the other end end 10b based on the cut other end end face 10b', the one end end 10a including the receiving port 10a is cut (dashed line _c2 portion) by taking a measurement from the cut other end end face 10b', and a straight pipe ₁₁₁ (hereinafter, ₁₁₁ , 111) of a required length is obtained. A straight pipe 111 is cut into two pieces (the general symbol for all _{11, 2} ... is "11"), and one of the ridges 12 is formed on the outer periphery of one end of the cut straight pipe 111 based on _one end face 10a', and the ridges 12, 12 on both ends of the straight pipe ₁₁₁ are finished symmetrically with respect to the center of the pipe axis (center line c) to produce the housing pipe _101. The ridges 12 can also be formed by cutting both ends 10a, 10b and then using the cut end faces 10a', 10b' as references.
In this configuration, the protrusions 12 are formed based on the cut end faces 10a', 10b' so that when the housing pipe 10 is connected with the housing joint 50, the protrusions 12 are located at positions corresponding to the housing joint 50 from the connecting opposing pipe end faces.

The above embodiment is advantageous in terms of cost because it can use a conventional die 1 as shown in FIG. 16, and it is also possible to cast a cast pipe 10 ₂ ′ without using a core 6 as shown in FIG. 3. In this case, the part corresponding to the receiving port 10 a becomes thick, and a large amount of molten metal a is wasted. To manufacture a housing pipe 10 ₂ from this cast pipe 10 ₂ ′, the same operation as in the above embodiment is performed as shown in the same figures (b) to (d). In this case, similarly, after cutting both ends of a straight pipe 11 ₂ to the required length (the dashed line c ₁ part and the dashed line c ₂ part), the protrusions 12 can be formed on both ends 10 a and 10 b based on the cut end faces 10 a ′ and 10 b ′.

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 die 1 shown in Fig. 16 may be used, but as shown in Fig. 4(a), a die 1a with a modified mouth portion and a modified core 6a may also be used. The core 6a is cylindrical with a flange and has grooves 6b for the ribs around its entire inner circumference. By feeding molten metal a into the rotating die 1a, a cast tube ₁₀₃ ' made of a straight tube is formed, and the molten metal a is allowed to flow into the grooves 6b to form the ribs 12 (the ribs 12 are formed by casting).

The cast pipe 10 ₃ ' is removed from the mold 1a by hooking the claws of a puller on the inner surface of the receiving port 10a and pulling it out from the mold 1a (FIG. 3(b)).
The cast pipe ₁₀₃ ' is cut (dashed line _c1 ) at the other end (insertion port) 10b of the cast pipe 103' from one end 10a, and the other ribs ₁₂ at both ends of the straight pipe ₁₁₃ are formed on the outer periphery of the other end based on the cut end face 10b'. The ribs 12, 12 at both ends 10a, 10b are finished symmetrically with respect to the center of the pipe axis (center line c) to produce the housing pipe ₁₀₃ (FIG. 1(d)). At this time, the one end 10a of the straight pipe ₁₀₃ can also be measured from the cut end face 10b' to produce the straight pipe ₁₁₃ of the required length.

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. 16 may be used, but as shown in FIG. 16(a), similar to the one shown in FIG. 4, a mold 1a is used with a deformed receiving portion and a deformed core 6a is used. The core 6a is cylindrical with a cover and has a groove 6b around its entire inner circumference. By feeding molten metal a into the rotating mold 1a, a cast tube ₁₀₄ ' consisting of a straight tube is formed, and the molten metal a is allowed to flow into the groove 6b to form a bulge 12c.

The cast pipe 10 ₄ ' is removed from the mold 1 by hooking the claws of a puller on the inner surface of the receiving port 10a and pulling it out from the mold 1 (FIG. 3(b)).
The other end (insertion port) end 10b of the demolded cast pipe ₁₀₄ ' is cut off (dashed line _c1 portion) by measuring from the end face 10a'' of one end 10a of the demolded cast pipe 104', and the other protrusion 12 of the straight pipe 11 is formed on the outer periphery of the other end 10b based on the cut end face 10b' of the other end (FIGS. 1(b) to 1(c)).

Next, the one end is cut (dashed line _c2 portion) by measuring from the cut other end surface 10b' to obtain a straight pipe ₁₁₄ of the required length (FIG. 1(c)), and one of the ridges 12 is formed on the outer periphery of the one end surface 10a' of the cut straight pipe ₁₁₄ based on the one end surface 10a'. The ridges 12, 12 on 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 (FIG. 1(d)). The one of the ridges 12 is formed by cutting the bulging portion 12c (see FIG. 8).

In manufacturing the housing pipes ₁₀₃ and ₁₀₄ in each of the above embodiments, if the cast end faces of both end portions 10a and 10b of the straight pipe 11 are clean and do not need to be cut, the straight pipe 11 can be measured to the required length without performing the above cuts _c1 and _c2 . In this case, it is also possible to cut only one of them.

The protrusions 12 are formed by the means shown in Figures 6 to 8. The means shown in Figure 6 involves forming a groove 13 around the entire outer periphery of the end of the straight pipe 11, fitting a ring 12a with a portion of its circumference missing into the groove 13, and welding 14 around the entire circumference.

The method shown in Figure 7 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 forming the protrusion 12 may be a partially notched ring 12a as shown in Figure 6(b), but it may also be a circular object 12b without a notch and continuous around the entire circumference as shown in Figure 7(b) (see Figure 7(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 circumference of the front and rear of the rings 12a and 12b.

The method shown in Figure 8 is when the protrusion 12 or bulge 12c is formed at one end 10a by centrifugal casting at the same time as the straight tube 11 is cast (Figures 4 and 5), and the protrusion 12 at the other end is formed by the method shown in Figures 6 and 7. In the case of the bulge 12c, the protrusion 12 is formed by cutting, as shown in Figure 8(a), by cutting the bulge 12c with a lathe or the like, and even in the case of the protrusion 12 that is cast as it is (Figure 4), it can be cut to shape as necessary.

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-plated or otherwise treated to prevent corrosion.

The order in which the protrusions 12 are formed on the straight pipe 11 may be appropriately considered, and may be, for example, the modes shown in Figs.
9 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 turned over 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 shape the ribs 12 and obtain the housing pipe 10.
In the drawing, e denotes a rail installed along the line of each processing machine A, B, C, and D, and a carriage carrying a cast pipe 10' (straight pipe 11) runs on this rail e via rolling wheels. Note that in the drawing, the rails e are separated vertically, but 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 depositing the cast pipe 10' from the rail e to another position (another rail), scooping it up from the other side, and returning it to the previous line (the cart on the rail e), etc. The same applies below. Note that the reversal can also be performed using a dedicated machine such as a reversing machine.

The embodiment shown in FIG. 10 is a case where the protrusions 12 of the housing tubes ₁₀₁ and 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. After that, the cast pipe 10' is turned over in its longitudinal direction and then sent to the cutting machine A to cut off one end (receptacle, flange) 10a, and then sent to the lathe D to form the groove 13 and fit the ring 12a into the groove 13. The straight pipe 11 with the ring 12a fitted therein is then sent to a welding machine C to weld 14 around the ring 12a, and then further sent to the lathe D to cut the ring 12a and the weld 14 to form one of the protrusions 12. The straight pipe 11 is then inverted lengthwise and fed into a welding machine C to weld 14 around the other ring 12a, and then fed into a lathe D to cut the ring 12a and the weld 14 to form the other protrusion 12 and obtain the housing pipe 10.

The embodiment shown in FIG. 11 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 10' 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 protrusions 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 the one end (receiving port) 10a is cut to obtain the housing pipe 10 with the protrusion 12 at the one end having a shaped one end.
In this embodiment, when forming one of the protrusions 12 of the housing pipe in Figure 5, after inversion, the bulge portion 12c is cut in the cast protrusion processing to form the protrusion 12 at one end side.

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. 14, using this housing pipe 10 will be described.
First, as shown in Fig. 15, 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. 13, the housing joint 50 consists 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 device) is reached, a T-shaped branch pipe (T-pipe) 40 is set at that position, as shown in Figure 14, 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 position of the emergency equipment H, and a pipe material connected to the B-cut short pipe 20 and the A-cut short pipe 30 is positioned and connected between the housing 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 housing pipe 10, etc. In this case, the piping length can be adjusted by adjusting the insertion of the insertion ports 21 in the K-shaped joints 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 protrusion.

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 Casting mold (metal mold, mold)
10, ₁₀₁ , ₁₀₂ , ₁₀₃ , ₁₀₄ Housing pipe 10', ₁₀₁ ', ₁₀₂ ', ₁₀₃ ', ₁₀₄ ' Cast pipe 10a One end side end part of housing pipe (socket)
10b Other end (insertion port)
11, 11 ₁ , 11 ₂ , 11 ₃ , 11 ₄ 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 (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 manufacturing method for a housing pipe in which a cast pipe (10') consisting of a straight pipe produced by centrifugal casting is moved along a line, and first, measurements are taken from one end face (10a'') of the cast pipe (10 ') to cut the other end face (10b), and a one-end rib (12) is formed on the outer circumferential surface of the other end face using the cut end face (10b') as a reference, and then, the cast pipe (10') is turned upside down in the longitudinal direction, and the one-end end face (10a) is cut with the cutting machine (A) that cut the other end face (10b) by taking measurements from the other end cut end face ( 10b'), and a one-end rib (12) is formed on the outer circumferential surface of the one end face using the cut end face (10a') as a reference. The method for manufacturing a housing tube according to claim 1, in which the protrusion (12) on the one end side is formed by pressing in a ring (12a, 12b), by forming a groove (13) on the outer circumferential surface of the one end side end (10a) and fitting a ring (12a, 12b) into the groove (13) and welding (14), or by forming a bulge (12c) on the outer circumferential surface of the one end side end (10a) and cutting the bulge (12c). 3. The method for manufacturing a housing tube according to claim 1 or 2 , wherein the protrusion (12) on the other end side is formed by pressing a ring (12a, 12b) into the housing tube, or by forming a groove (13) on the outer circumferential surface of the other end side and fitting and welding (14) the ring (12a, 12b) into the groove (13).

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