JP7479906B2 - Manufacturing method of lower connection part, manufacturing method of collective joint, collective joint - Google Patents

Description

The present invention relates to a joint assembly and a piping structure.

In multi-story buildings such as apartment buildings, horizontal branch pipes are installed to introduce wastewater from sanitary equipment in the rooms on each floor, and these horizontal branch pipes are connected to vertical drainage pipes inside the pipe shaft so that the wastewater can flow into the sewer.

A plastic joint member called a drainage manifold is placed where the vertical drainage pipe connected to the horizontal branch pipe penetrates the floor slab. This drainage manifold has an upper connection pipe that connects the vertical drainage pipe, and a horizontal branch pipe connection part formed on the side of the upper connection pipe. It also has a lower connection part that is connected to the drainage manifold and drains the drainage collected from the horizontal branch pipe and vertical drainage pipe downward, and a vertical drainage pipe that connects to the lower connection part.

Because the lower connection needs to pass drainage from the horizontal branch pipe and vertical drain pipe, the drainage volume of the lower connection is larger than that of the horizontal branch pipe and vertical drain pipe. For this reason, the part of the lower connection close to the drainage manifold is usually made with a larger diameter. On the other hand, the vertical drain pipe connected to the lower connection is required to occupy less space, so its diameter needs to be as small as possible. For this reason, the lower connection is usually designed with a narrowing diameter toward the tip.

For example, Patent Document 1 discloses a drainage pipe joint in which a vertical drainage pipe with a spigot at the end is inserted into a lower connection part with a socket at the end.

JP 2012-97551 A

However, when using the drain pipe joint disclosed in Patent Document 1, the receiving port at the end of the lower connection part and the vertical drain pipe must be adhesively joined during construction. Therefore, the watertightness of the joint between the lower connection part and the vertical drain pipe depends on the adhesive, making construction difficult.

On the other hand, if the tip of the lower connection part is an insertion port, a packing material can be used to join the lower connection part and the vertical drain pipe. However, there is a risk that the watertightness of the joint will be insufficient because a drainage passage will be created at the part where the parting line on the outer surface of the lower connection part joins with the packing material.

The present invention has been made to solve the above problems, and aims to provide a collective joint and piping structure that is easy to install and has excellent watertightness.

In order to solve the above problems, the collective joint and piping structure according to the present invention have the following features.
(1) A lower connection portion includes a tapered portion that narrows toward a tip end, and a spigot that is provided at the tip end of the tapered portion and has no parting line on an outer surface,
A connector, characterized in that the outer diameter of the spigot becomes smaller toward the tip of the spigot.
(2) The collective joint according to (1), characterized in that the inner surface of the tapered portion of the collective joint has swirl vanes.
(3) The collective joint according to (1) or (2), characterized in that the inner diameter of the spigot increases toward the tip of the spigot.
(4) The collective joint according to any one of (1) to (3),
A piping structure comprising a receiving pipe connected to the spigot via a packing material.
(5) A piping structure according to (4), characterized in that the packing material has only one lip portion.
(6) The piping structure according to (5), wherein the length of the lip portion is 10 mm or less.

In the collective joint described in (1), there is no parting line on the outer surface of the spigot provided at the lower connection part. Therefore, when the packing material is attached to the spigot, no gap is generated between the spigot and the packing material. This makes it possible to prevent water from leaking between the spigot and the packing material.
In addition, compared to when the lower connection part is a socket, the joint with a spigot provided at the lower connection part is structured to be less susceptible to water leakage. Furthermore, during construction, there is no need to adhesively join the joint with a spigot provided at the lower connection part and the socket pipe connected to the lower connection part.
Furthermore, in the collective joint described in (1), the outer diameter of the spigot becomes smaller toward the tip. As a result, after the spigot is molded with a die, the outer surface of the spigot can be used as a draft taper to pull the cavity mold in the direction toward the tip of the spigot. Therefore, it is not necessary to divide the cavity mold that molds the outer surface of the spigot. As a result, after the spigot is molded with a die, there is no parting line on the outer surface of the spigot. Therefore, it is possible to save time and effort compared to removing the parting line from a collective joint in which a parting line is formed in advance on the outer surface of the spigot.

The collective joint described in (2) has a swirl vane on the inner surface of the tapered portion of the collective joint. This can improve the drainage performance of the collective joint.

In the collective joint described in (3), the inner diameter of the spigot increases toward the tip. Therefore, after the spigot is molded using a die, the core mold can be removed in a direction toward the tip of the spigot. The core mold for forming the tapered portion is removed in the direction opposite to the direction toward the tip of the spigot, so that different core molds can be used for the tapered portion and the spigot when molding the collective joint using a die. As a result, the core mold for forming the tapered portion can be divided into multiple parts. Therefore, the swirl vanes can be molded using a die between the multiple divided core molds, eliminating the need to join the swirl vanes to the inner surface of the tapered portion.

The piping structure described in (4) includes the collective joint described in any one of (1) to (3), a spigot having no parting line provided on the collective joint, and a receiving pipe joined to the spigot via a packing material. Therefore, no gap is generated between the spigot and the packing material. As a result, it is possible to prevent water from leaking between the spigot and the packing material.
In addition, compared to when the lower connection part of the collective joint is a socket, the collective joint with a spigot provided at the lower connection part is structured to be less susceptible to water leakage. Furthermore, during construction, there is no need to adhesively join the collective joint with a spigot provided at the lower connection part and the socket pipe connected to the lower connection part.
Therefore, when the piping structure described in (4) is used, excellent workability and watertightness can be obtained.

In the piping structure described in (5), the packing material has only one lip portion. The piping structure has sufficient watertightness even when the packing material has only one lip portion due to the spigot that does not have a parting line provided in the collective joint.

In the piping structure described in (6), the length of the lip portion is 10 mm or less. Due to the spigot that does not have a parting line provided in the collective joint, even if the length of the lip portion is 10 mm or less, the piping structure has sufficient watertightness.

According to the present invention, when the packing material is attached to the spigot, no gap occurs between the spigot and the packing material, so water leakage from between the spigot and the packing material can be prevented. Therefore, it is possible to provide a collective joint and piping structure that is easy to install and has excellent water-tightness.

FIG. 2 is a partial cross-sectional view of a collective joint according to an embodiment of the present invention. FIG. 4 is a partial cross-sectional view showing a swirl vane provided on a tapered portion of the collective joint. FIG. 4 is a partial cross-sectional view showing that the inner diameter of the spigot of the same collective joint increases toward the tip. FIG. 2 is a partial cross-sectional view of a piping structure according to an embodiment of the present invention. FIG. 4 is a cross-sectional view of a packing material of the piping structure. FIG. 2 is a partial cross-sectional view of a piping structure according to an embodiment of the present invention.

An embodiment of the present invention will now be described with reference to the drawings. First, a group joint according to an embodiment of the present invention will be described.
The collection joint 10 is used in multi-story buildings, such as apartment buildings, to collect wastewater from each floor and drain it to the lower floors.

As shown in FIG. 6, the assembly joint 10 according to the embodiment of the present invention has a horizontal pipe connection portion 41, an upper connection pipe 42, an intermediate pipe 43, a lower connection portion 1, a sound-insulating cover layer 44, and an expansion and contraction absorbing member 45.

The upper connecting pipe 42 extends in the vertical direction.
The upper connecting pipe 42 may have a damming plate on its inner surface. The damming plate is preferably installed at an angle of -30° to 20° from the vertical. If the installation angle is inclined more than 20°, the swirling flow of the wastewater swirled by the inclined plate may not be sufficiently blocked, and backflow into the horizontal branch pipe may occur. Also, if the installation angle is inclined more than -30°, the rebound of the received wastewater may become large, which may disrupt the flow of the wastewater and increase the pressure fluctuation inside the pipe.

The upper connecting pipe 42 is made of, for example, a polyvinyl chloride resin composition containing 0.1 to 1.0 parts by weight of non-expandable graphite per 100 parts by weight of polyvinyl chloride resin. The upper connecting pipe 42 is obtained, for example, by injecting and filling the polyvinyl chloride resin composition into the cavity of a molding machine.

The horizontal pipe connecting portion 41 extends radially outward from the peripheral wall of the upper connecting pipe 42 in a direction perpendicular to the central axis. In the present embodiment, three horizontal pipe connecting portions 41 are disposed in the circumferential direction of the upper connecting pipe 42.
Two of the three horizontal pipe connecting parts 41 are individually disposed at positions on either side of the central axis in the radial direction. The remaining horizontal pipe connecting parts 41 extend in a radial direction perpendicular to the central axis, and form an angle of 90° in plan view with the directions in which the two horizontal pipe connecting parts 41 extend.
The number and extending direction of the horizontal pipe connecting portions 41 are not limited to this embodiment and can be changed as desired.

The intermediate pipe 43 is connected to the lower end of the upper connecting pipe 42. The outer diameter of the intermediate pipe 43 is smaller than the outer diameter of the upper connecting pipe 42 at the upper connecting pipe 42. The upper part of the peripheral wall of the intermediate pipe 43 is fitted inside the lower end of the upper connecting pipe 42.
The intermediate pipe 43 is made of a resin composition containing, for example, a polyvinyl chloride resin and thermally expandable graphite, which is a thermally expandable fire-resistant material. That is, the intermediate pipe 43 is produced by molding a resin composition containing the thermally expandable fire-resistant material. The intermediate pipe 43 is produced by, for example, extrusion molding the resin composition.

The intermediate tube 43 may have a single-layer structure in which the entire intermediate tube 43 is made of a resin composition containing a heat-expandable fire-resistant material, or may have a multi-layer structure made of multiple layers. In the case of a multi-layer structure, any one of the layers may be formed from a resin composition containing a heat-expandable fire-resistant material. For example, when the intermediate tube 43 has a three-layer structure consisting of a surface layer, an intermediate layer, and an inner layer, the intermediate layer may be formed from a resin composition containing a heat-expandable fire-resistant material, and the surface layer, intermediate layer, and inner layer may contain a heat-absorbing agent.

As an example, a single-layer structure made of a resin composition containing 1 to 20 parts by weight of thermally expandable graphite per 100 parts by weight of polyvinyl chloride resin can be used. Alternatively, a three-layer structure made of a thermally expandable fire-resistant layer made of a resin composition containing 1 to 20 parts by weight of thermally expandable graphite per 100 parts by weight of polyvinyl chloride resin and a coating layer of a polyvinyl chloride resin composition not containing thermally expandable graphite that covers the inner and outer surfaces of the thermally expandable fire-resistant layer can be used.
In addition, if the intermediate pipe 43 does not contain thermally expandable graphite, a sheet-shaped fire-resistant material containing thermally expandable graphite may be wrapped around the outer surface of the intermediate pipe 43 and the fire-resistant material may be embedded in the floor slab penetration portion.

When the intermediate tube 43 has a single-layer structure, if the amount of thermally expandable graphite is less than 1 part by weight, sufficient thermal expandability may not be obtained during combustion, and the desired fire resistance may not be obtained. If the amount of thermally expandable graphite exceeds 20 parts by weight, the graphite may expand too much when heated, and the shape may not be retained, causing residues to fall off, resulting in reduced fire resistance.
When the intermediate tube 43 has a multi-layer structure, the fire-resistant, heat-expandable resin composition that forms the heat-expandable, fire-resistant layer is not particularly limited, but it is preferable that the composition contains 1 to 20 parts by weight of heat-expandable graphite per 100 parts by weight of polyvinyl chloride resin, more preferably 1 to 15 parts by weight, and even more preferably 2 to 10 parts by weight.
That is, if the amount of thermally expandable graphite is less than 1 part by weight, sufficient thermal expansion is not obtained during combustion, and the desired fire resistance may not be obtained.If the amount of thermally expandable graphite is more than 20 parts by weight, the graphite may expand too much upon heating, and the shape may not be retained, causing residues to fall off, resulting in a decrease in fire resistance.

Examples of the polyvinyl chloride resin include polyvinyl chloride homopolymers; copolymers of vinyl chloride monomers and monomers having unsaturated bonds copolymerizable with the vinyl chloride monomers; and graft copolymers in which vinyl chloride is graft-copolymerized onto (co)polymers other than vinyl chloride. These may be used alone or in combination of two or more kinds.
If necessary, the polyvinyl chloride resin may be chlorinated.

The thermally expandable graphite used in the present embodiment can be, for example, a crystalline compound obtained by subjecting powder of natural scaly graphite, pyrolytic graphite, kish graphite, or the like to an acid treatment using an inorganic acid and a strong oxidizing agent to insert the inorganic acid between the layers of the graphite, and then adjusting the pH.
As the inorganic acid, concentrated sulfuric acid, nitric acid, selenic acid, etc. can be used. As the strong oxidizing agent, concentrated nitric acid, perchloric acid, perchlorates, permanganates, dichromates, hydrogen peroxide, etc. can be used.
By adjusting the pH, it is possible to use thermally expandable graphite which is a crystalline compound that maintains the layered structure of carbon and has a pH adjusted to 1.5 to 4.0, and thermally expandable graphite having a 1.3-fold expansion temperature of 180° C. to 240° C.

Additives such as stabilizers, inorganic fillers, flame retardants, lubricants, processing aids, impact modifiers, heat resistance improvers, antioxidants, light stabilizers, UV absorbers, pigments, plasticizers, and thermoplastic elastomers may be added to the resin composition constituting the intermediate tube 43 as necessary, within the scope that does not impede the purpose of this embodiment. It is preferable that the intermediate tube 43 satisfies the performance described in JIS K6741.

In addition, the intermediate pipe 43 provided in this embodiment may be omitted.
For example, the intermediate pipe 43 may be omitted, and the lower connection part 1 may be directly fitted and connected to the lower end of the upper connection pipe 42. In the case of this connection structure, it is preferable to provide a fire-resistant layer containing the above-mentioned thermally expandable fire-resistant material around (on) the part connecting the upper connection pipe 42 and the tapered part 11.

It is preferable that a sound-insulating cover layer 44 is formed on the outer periphery of the upper connecting pipe 42 and the outer periphery of the tapered portion 11 to cover them.
The sound-insulating cover layer 44 is preferably a sheet having a thickness of about 0.8 to 2.2 mm made of soft polyvinyl chloride, butyl rubber, polypropylene (PP), etc. Alternatively, in addition to these sheets, a laminate having polyester fiber, urethane foam, or glass wool having a thickness of about 5 to 20 mm laminated on the inside of the sheet may be used.
The sound insulating cover layer 44 can be a sheet or laminate that is wrapped around the joint assembly 10 on-site before or after installation, or can be provided as a pre-injected sound insulating layer when the joint assembly 10 is manufactured in a factory.
In addition, in the structure of the collective joint 10 shown in Fig. 6, the sound-insulating cover layer 44 may be omitted. If the sound-insulating cover layer 44 is omitted, it is desirable to make the minimum thickness of each part of the collective joint as thick as possible in order to improve the sound insulation of the collective joint 10.

(Collective joint)
As shown in Figure 1, a collective joint 10 according to an embodiment of the present invention has a lower connection part 1 having a tapered section 11 that reduces in diameter toward the tip, and a spigot 12 that is provided at the tip of the tapered section 11 and has no parting line on its outer surface. The collective joint 10 according to an embodiment of the present invention is characterized in that the outer diameter of the spigot 12 decreases toward the tip of the spigot 12. The tapered section 11 and spigot 12 of the lower connection part 1 are formed by molding from, for example, a synthetic resin material.

As a result, there is no parting line on the outer surface of the spigot 12 provided in the lower connection part 1, so when the packing material 22 is attached to the spigot 12, no gap is generated between the spigot 12 and the packing material 22. This makes it possible to prevent water from leaking from between the spigot 12 and the packing material 22.
In addition, compared to when the lower connection part 1 is a socket, the joint 10 in which the lower connection part 1 is provided with a spigot 12 is structured to be less susceptible to water leakage. Furthermore, during construction, there is no need to adhesively join the joint 10 in which the lower connection part 1 is provided with a spigot 12 and the socket pipe 2 connected to the lower connection part 1.

Furthermore, because the outer diameter of the spigot 12 becomes smaller toward the tip, after the spigot 12 is molded, the cavity mold can be removed in the direction toward the tip of the spigot 12. Therefore, there is no need to divide the cavity mold that molds the outer surface of the spigot 12. Since there is no parting line on the outer surface of the spigot 12 after the spigot 12 is molded, the effort of removing the parting line on the outer surface of the spigot 12 can be eliminated.

When molding the lower connection portion 1, for example, a cavity mold 30 having a parting line at the connection portion between the tapered portion 11 and the spigot 12 can be used.
That is, the cavity mold 30 includes a first cavity mold 31 and a second cavity mold 32. A joining surface PL1 between the first cavity mold 31 and the second cavity mold 32 (hereinafter referred to as the first joining surface PL1) is located at the connection portion 14 between the tapered portion 11 and the spigot 12. In other words, the first cavity mold 31 molds the tapered portion 11 of the lower connection portion 1. The first cavity mold 31 is divided into two in a direction perpendicular to the tube axis O. The joining surfaces (not shown) of the two first cavity molds 31 (hereinafter referred to as the second joining surfaces) are located on the outer peripheral surface of the tapered portion 11 and extend in the direction of the tube axis O. The second cavity mold 32 molds the spigot 12 of the lower connection portion 1. In the illustrated example, the core mold 50 is integral over the entire length of the tapered portion 11 and the spigot 12.
The above-described cavity mold 30 and core mold 50 are assembled, material is injected into them to form the lower connection part 1, and then the cavity mold 30 and core mold 50 are each removed from the lower connection part 1.
At this time, the two first cavity molds 31 are each demolded from the tapered portion 11 in a direction D1 perpendicular to the tube axis O. As a result, a second parting line (protrusion) (not shown) extending in the tube axis O direction remains in the tapered portion 11. This second parting line is a trace of the second split surface. The second parting line extends over the entire length of the tapered portion 11 in the tube axis O direction.
At this time, the second cavity mold 32 is demolded from the lower connection portion 1 downward D2. As a result, a first parting line (projection) (not shown) extending around the tube axis O remains at the connection portion 14 between the tapered portion 11 and the spigot 12. This first parting line is a trace of the first parting surface. The first parting line extends around the entire circumference of the connection portion 14.
As a result, after molding the lower connection portion 1, it is possible to obtain a spigot 12 that does not have a parting line on its outer surface. In addition, since the cavity mold has a second parting line at the boundary (connection portion 14) between the tapered portion 11 and the spigot 12, the cavity mold that molds the spigot can be removed in the direction toward the tip of the spigot 12. This results in a configuration in which the outer diameter of the spigot 12 becomes smaller toward the tip of the spigot 12.
After molding, the core mold 50 can be removed in the upward direction D3, which is the opposite direction to the direction toward the tip of the spigot 12.

As shown in FIG. 2, the collective joint 10 according to this embodiment may have swirl vanes 13 on the inner surface of the tapered portion 11. This can improve the drainage performance of the collective joint 10.

The swirl vanes 13 are supported by the swirl vane support legs so that, for example, the projected area of the swirl vanes 13 as viewed in the pipe axis O direction is 5% to 30% of the internal cross-sectional area of the tapered section 11, and the inclination angle is 20° to 50°. The swirl vane support legs extend almost entirely from the lower end of the fitting section with a width roughly the same as the horizontal width of the swirl vanes 13, and the lower edge is inclined to follow the inclination of the swirl vanes 13. The swirl vane support surface of the swirl vane support legs is formed in an arc-shaped cross section, and supports the swirl vanes 13 slightly above the lower edge.

If the inclination angle is too small, the downstream drainage water cannot be adequately received, and sufficient deceleration and swirling force cannot be obtained. As a result, there is a risk that sufficient drainage performance cannot be obtained. On the other hand, if the inclination angle of the swirling blade 13 is too large, when the downstream drainage water hits the swirling blade 13, it bounces back toward the center of the pipe to a large extent, making it difficult to ensure a center of flow in the vertical drainage pipe, and as a result, there is a risk that sufficient drainage performance cannot be obtained.

The swirl vanes 13 may be formed integrally with the tapered portion 11, for example, by die molding, or may be joined to the inner surface of the tapered portion 11 after the tapered portion 11 is molded.

When molding the lower connection part 1, the same cavity mold 30 and core mold 50 as described in FIG. 1 can be used. In this case, after the lower connection part 1 is molded with a die, the swirl vane 13 is joined to the inner surface of the tapered part.

On the other hand, when the swirl vane 13 is formed integrally with the tapered portion 11 by die molding, as shown in FIG. 3, it is preferable that the inner diameter of the spigot 12 of the collective joint 10 according to this embodiment increases toward the tip of the spigot 12.

As a result, after the spigot 12 is molded with a die, the inner surface of the spigot 12 can be used as a draft taper to pull the core die 52 in a direction D4 toward the tip of the spigot 12. The core die 51 for molding the tapered portion 11 uses the inner surface of the tapered portion 11 as a draft taper to pull in a direction D3 opposite to the direction toward the tip of the spigot 12, so that when the collective joint 10 is molded with a die, different core dies 51, 52 can be used for the tapered portion 11 and the spigot 12. That is, in this case, the core die 50 includes a first core die 51 for molding the tapered portion 11 and a second core die 52 for molding the spigot 12. The swirl vane 13 is molded between the first core die 51 and the second core die 52.
After injection molding, the first core die 51 is demolded in an upward direction D3 relative to the lower connection portion 1, and the second core die 52 is demolded in a downward direction D4 relative to the lower connection portion 1.
In this way, it is possible to separate the core mold for molding the tapered portion 11. As a result, the swirl vanes 13 can be molded by a die, and the effort of joining the swirl vanes 13 to the inner surface of the tapered portion 11 can be eliminated.

When molding the lower connection portion 1, the inner surface of the tapered portion can be formed using a core mold, for example, a core mold in which the first core mold 51 is divided into multiple parts. This allows the swirl vanes to be molded using the first core mold 51 divided into multiple parts.

Next, we will explain the piping structure according to an embodiment of the present invention.

(Piping structure)
As shown in Fig. 4, the piping structure according to the embodiment of the present invention has the above-mentioned assembly joint 10 and a socket pipe 2 to which a spigot 12 is joined via a packing material 22. The socket pipe 2 may have a socket portion 21 and a vertical pipe 23.

This prevents a gap from occurring between the spigot 12 and the packing material 22. As a result, water can be prevented from leaking from between the spigot 12 and the packing material 22.
Also, compared to when the lower connection portion 1 of the collective joint 10 is a socket, the collective joint 10 in which the lower connection portion 1 is provided with a spigot 12 is structured to be less susceptible to water leakage. Furthermore, during construction, there is no need to adhesively join the collective joint 10 in which the lower connection portion 1 is provided with a spigot 12 and the socket pipe 2 connected to the lower connection portion 1.

In addition, the joining work of the piping structure can be completed by continuing the insertion work until the spigot 12 hits the receiving portion 21. This allows the worker to clearly recognize when the joining is complete, and provides a piping structure with excellent workability and watertightness.

The receiving pipe 2 is made of, for example, a rigid polyvinyl chloride resin composition, and is obtained, for example, by injecting and filling the polyvinyl chloride resin composition into the cavity of a molding machine.
In addition, when the receiving pipe 2 penetrates the floor of a fire compartment, it is preferable to make it from a fire-resistant material in order to ensure fire resistance. In this case, for example, the receiving pipe 2 preferably contains 1 to 20 parts by weight of thermally expandable graphite per 100 parts by weight of polyvinyl chloride resin, more preferably 1 to 15 parts by weight, and even more preferably 2 to 10 parts by weight.

The packing material 22 is made of a rubber material that is typically used in drainage equipment, such as ethylene-propylene-diene rubber or silicone rubber. From the perspective of a balance between heat resistance, durability, and cost, it is preferable to make the packing material 22 from EPDM.

As shown in FIG. 5, in the piping structure according to the embodiment of the present invention, it is preferable that the packing material 22 has only one lip portion. The piping structure according to the embodiment of the present invention does not have a parting line on the outer surface of the spigot 12 provided in the lower connection portion 1, so when the packing material 22 is attached to the spigot 12, no gap is generated between the spigot 12 and the packing material 22. Therefore, even if the packing material 22 has only one lip portion, sufficient water stopping properties can be ensured. Therefore, the structure of the packing material 22 can be simplified, thereby reducing construction costs.

In the piping structure according to the embodiment of the present invention, it is more preferable that the length of the lip portion of the packing material 22 is 10 mm or less. As described above, even if the length of the lip portion is 10 mm or less, sufficient water stopping performance can be ensured. Therefore, construction costs can be further reduced.

The piping structure according to an embodiment of the present invention may be provided with an expansion/contraction absorbing member between the receiving portion 21 of the receiving pipe 2 and the spigot 12 of the collective joint 10. This prevents unnecessary load from being applied to the collective joint 10 and the receiving pipe 2 even if the collective joint 10 and the receiving pipe 2 mainly thermally expand or contract in the direction along the central axis as the outside air temperature rises or falls. Therefore, the receiving portion of the receiving pipe 2 is less likely to crack due to thermal expansion.

If the expansion and contraction absorbing member is ring-shaped, it can be reliably positioned around the entire circumference between the receiving portion 21 and the spigot 12. Therefore, even if uneven expansion occurs around the entire circumference of the receiving portion 21, the expansion and contraction absorbing member can absorb the deformation around the entire circumference.

Furthermore, the technical scope of the present invention described above is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
In addition, within the scope of the invention, the components in the above-described embodiments may be replaced with well-known components, and the above-described embodiments may be combined as appropriate.
For example, a receiving pipe may be joined to the horizontal pipe connection portion or the upper connection pipe.

The present invention can be widely applied to various types of pipe joints, such as drainage joints in multi-story buildings such as apartment buildings, or general joints and cleaning port joints.

Reference Signs List 10: Collective joint 1: Lower connection portion 11: Tapered portion 12: Spigot 13: Swirl vane 2: Socket pipe 21: Socket portion 22: Packing material 221: Lip portion 222: Length of lip portion 23: Vertical pipe 3: Piping structure 41: Horizontal pipe connection portion 42: Upper connection pipe 43: Intermediate pipe 44: Sound insulation cover layer 45: Expandable absorbing member

Claims (4)

A method for manufacturing a lower connection comprising: a tapered section provided at a lower part of a collective joint, the tapered section tapering toward a tip thereof, and having a parting line extending in a pipe axis direction on an outer surface thereof; swirl vanes provided on an inner surface of the tapered section; and a spigot provided at the tip of the tapered section, the spigot having no parting line on its outer surface thereof, the outer diameter of the spigot decreasing toward the tip of the spigot,
The lower connection portion is molded by injecting a resin material into a mold formed by combining a cavity mold and a core mold,
The core die includes a first core die that forms an inner surface of the tapered portion and a second core die that forms an inner surface of the spigot,
The swirl vane is molded between the first core die and the second core die,
The cavity mold includes a first cavity mold for forming an outer surface of the tapered portion and a second cavity mold for forming an outer surface of the spigot,
the first cavity mold is divided into two by a dividing surface extending in the tube axis direction,
The two first cavity dies are removed from the tapered portion in a direction perpendicular to the tube axis direction,
The second cavity mold is removed from the spigot toward the tip of the spigot.
A method for manufacturing the lower connection part. A method for manufacturing a collective joint, comprising connecting a lower end of an upper connecting pipe having a horizontal pipe connecting portion to an upper end of a lower connecting portion manufactured by the method for manufacturing a lower connecting portion according to claim 1. A collective joint comprising: a tapered section which reduces in diameter toward a tip and has a parting line extending in a pipe axial direction on its outer surface ; swirl vanes provided on an inner surface of the tapered section; a spigot provided at the tip of the tapered section and having no parting line on its outer surface, the spigot having an outer diameter decreasing toward the tip of the spigot; and an upper connecting pipe connected to an upper portion of the lower connecting section,
The lower connection portion is
a first parting line provided on an outer surface of a connection portion between the tapered portion and the spigot;
a second parting line extending in the pipe axis direction on an outer surface of the tapered portion . 4. The assembly joint of claim 3 , wherein an inside diameter of the spigot increases toward a tip of the spigot.

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