JP2023176039A - Electric fusion joint - Google Patents

Abstract

To provide an electric fusion joint capable of stably forming a bead and suppressing stagnation of water.SOLUTION: In an electric fusion joint 1, a cylindrical part 21 is formed cylindrical and includes joint receiving port parts 23 and 24 in which resin pipes 11 and 12 containing thermoplastic resins can be inserted. A stopper part 22 is provided on an inner surface 21a of the cylindrical part 21 so as to protrude inside and regulates insertion positions of pipe ends 11a and 12a of the resin pipes 11 and 12 in a case where the resin pipes 11 and 12 are inserted inside of the joint receiving port parts 23 and 24. Receiving port heating parts 3 and 4 include heating wires 31 and 41 which are coated with insulators and disposed in the joint receiving port parts. A stopper heating part 5 includes a heating wire 51 which is coated with an insulator and disposed in the stopper part 22. A height (h) of the stopper 22 protruding from the inner surface 21a is 20% or more and 80% or less of a thickness d3 of the resin pipes 11 and 12 to be inserted. When a volume of the stopper part is defined as V and a product of a cross-sectional area and the thickness of the resin pipes 11 and 12 is defined as P, V<P is satisfied.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD This disclosure relates to electrofusion joints.

BACKGROUND ART Electric fusion joints are often used to connect pipes made of resin, such as resin pipes and metal-reinforced composite pipes having a resin layer and a metal reinforcing layer (for example, see Patent Document 1).

For example, the electric fusion joint shown in Patent Document 1 includes a joint body made of thermoplastic resin in which tube sockets are formed at both ends into which pipes to be connected are inserted, and an inner circumferential surface of the joint body. A stopper portion that protrudes toward the front is provided. The stopper portion regulates the position of the tube inserted into the tube socket. A heating element is provided in each of the pipe socket and the stopper part, and by generating heat from the heating element, the resin around the heating element and the resin of the pipe are fused, and the electric fusion joint and the pipe are connected. .

Japanese Patent Application Publication No. 5-87286

However, in the configuration of Patent Document 1, if the dimensions of the stopper part are not appropriate, the bead becomes too large and a retention part where water accumulates is formed, or the clevis (gap) between the stopper part and the pipe end becomes too large. There was a risk that it would not be completely filled and a stagnant portion would remain. 14(a) and 14(b) are cross-sectional views showing a state in which pipes 1001 and 1002 are fusion-bonded to a conventional electric fusion joint 1000. FIG. 14(a) is a diagram showing a state in which the bead 1003 has become too large. When water flows from the pipe 1002 toward the pipe 1001 (see arrow), a portion 1004 (see dotted line) where water accumulates is generated on the pipe 1001 side of the bead 1003. Moreover, FIG. 14(b) is a diagram showing a state in which the space between the pipe 1001 and the pipe 1002 is not filled completely and a clevis 1005 is generated. In the state shown in FIG. 14(b), water remains in the clevis 1005.

An object of the present disclosure is to provide an electric fusion joint that can stably form a bead and suppress water retention.

In order to achieve the above object, an electric fusion joint according to a first aspect includes a cylindrical part, a stopper part, a socket heat generating part, and a stopper heat generating part. The cylindrical part is cylindrical and has a joint socket into which a tube containing a thermoplastic resin can be inserted. The stopper part is provided on the inner surface of the cylindrical part so as to protrude inward, and regulates the insertion position of the pipe end of the pipe when the pipe is inserted inside the joint socket part. The socket heat generating part has a heating wire arranged in the joint socket part. The heat generating part of the stopper. It has a heating wire coated with an insulator and placed in the stopper part. The height of the stopper portion protruding from the inner surface is 20% or more and 80% or less of the wall thickness of the inserted tube. If the volume of the stopper portion is V and the product of the cross-sectional area and wall thickness of the tube is P, then V<P is satisfied.

Beads are formed by melting the resin of the stopper part and the resin of the pipe end surface, so by appropriately setting the dimensions of the stopper part to match the dimensions of the pipe end, which vary depending on the size of the pipe, it is possible to form beads stably. water can be formed and water retention can be suppressed.

If the height of the stopper exceeds 80% of the wall thickness of the tube, the stopper will melt after welding starts, and when the tube is pushed in, the heating wire in the stopper can pop out onto the inner surface of the tube. There is sex. If the heating wire is exposed, it is not preferable because the electric fusion joint of this embodiment cannot be used in the field of purified water. In addition, if the height of the stopper part is less than 20% of the wall thickness of the tube, the portion of the tube end close to the inner circumferential surface of the tube will not be sufficiently heated during fusion, and the fusion of the tube end will fail. This is not preferable because it may become insufficient and crevices may occur.

Therefore, by setting the height of the stopper part protruding from the inner surface to 20% or more and 80% or less of the wall thickness of the inserted pipe, it is possible to suppress the occurrence of clevises and form a stable bead. Retention of water can be suppressed.

Thereby, beads can be stably formed and water retention can be suppressed.

The electric fusion joint according to the second aspect includes a cylindrical part, a stopper part, a socket heat generating part, and a stopper heat generating part. The cylindrical portion has a pair of joint socket portions into which a tube containing a thermoplastic resin can be inserted. It is provided so as to protrude inward from the inner surface of the cylindrical portion, and regulates the insertion position of the tube end of each tube when the tube is inserted inside each joint socket. The socket heat generating part has a heating wire arranged in the joint socket part. The stopper heat generating part has a heating wire coated with an insulator and arranged in the stopper part. The height of the stopper portion protruding from the inner surface is 20% or more and 80% or less of the wall thickness of the inserted tube. The volume of the stopper part is V, the volume of the stopper part V in the width range along the axis of the stopper part after welding is Vp, and the part sandwiched between the wall thicknesses of the pipe after welding is Vp. When the volume is V', (V-Vp)/(V'-Vp)×100(%) is 120% or more and 300% or less.

Beads are formed by melting the resin of the stopper part and the resin of the pipe end surface, so by appropriately setting the dimensions of the stopper part to match the dimensions of the pipe end, which vary depending on the size of the pipe, it is possible to form beads stably. water can be formed and water retention can be suppressed.

In addition, if the height of the stopper exceeds 80% of the wall thickness of the resin pipe, the stopper will melt after fusion starts and the heating wire of the stopper will pop out onto the inner surface of the pipe when the pipe is pushed in. there is a possibility. If the heating wire is exposed, it is not preferable because the electric fusion joint of this embodiment cannot be used in the field of purified water. In addition, if the height of the stopper part is less than 20% of the wall thickness of the tube, the portion of the tube end close to the inner circumferential surface of the tube will not be sufficiently heated during fusion, and the fusion of the tube end will fail. This is not preferable because it may become insufficient and crevices may occur.

Therefore, by setting the height of the stopper part protruding from the inner surface to 20% or more and 80% or less of the wall thickness of the inserted pipe, it is possible to suppress the occurrence of clevises and form a stable bead. Retention of water can be suppressed.

Furthermore, if the value of (V-Vp)/(V'-Vp)×100(%) is larger than 300%, the bead becomes too large, and if it is smaller than 120%, the voids cannot be completely filled.

Therefore, by setting (V-Vp)/(V'-Vp)×100(%) to 120% or more and 300% or less, beads can be stably formed and water retention can be suppressed.

The electric fusion joint according to the third aspect is the electric fusion joint according to the first aspect, where V and P satisfy 0.21≦V/P≦0.74.

Thereby, beads can be stably formed and water retention can be suppressed.

According to the present disclosure, it is possible to provide an electric fusion joint that can stably form a bead and suppress water retention.

FIG. 2 is an external view showing an electrical fusion joint and a resin pipe connected to the electrical fusion joint in an embodiment of the present disclosure. FIG. 2 is a cross-sectional configuration diagram showing the electric fusion joint of FIG. 1. FIG. FIG. 2 is a cross-sectional configuration diagram showing a state in which a resin pipe and a resin pipe are inserted into the electric fusion joint shown in FIG. 1; FIG. 3 is an enlarged cross-sectional view of the vicinity of the stopper portion. FIG. 2 is a perspective view showing a jig used in the connection method according to the embodiment of the present disclosure. FIG. 8 is a diagram showing a resin pipe, an electric fusion joint, and a resin pipe attached to the jig shown in FIG. 7; FIG. 9 is a side view of FIG. 8; FIG. 2 is a flow diagram showing a connection method according to an embodiment of the present disclosure. FIG. 3 is a cross-sectional configuration diagram showing an electric fusion joint and a resin pipe after fusion bonding. (a) to (d) Diagrams for explaining the volume relationship between the compensation portion of the stopper portion and the gap for forming a bead. (a) A sectional view showing an electrical fusion joint in another embodiment of the present disclosure and a resin pipe connected to the electrical fusion joint, (b) an electrical fusion joint in another embodiment of the present disclosure. FIG. 3 is a sectional view showing a resin pipe connected to an electric fusion joint. (a) A sectional view showing an electrical fusion joint in another embodiment of the present disclosure and a resin pipe connected to the electrical fusion joint, (b) an electrical fusion joint in another embodiment of the present disclosure. FIG. 3 is a sectional view showing a resin pipe connected to an electric fusion joint. FIG. 3 is a sectional view showing an electric fusion joint and a resin pipe used in an example. (a) A diagram showing a state where a bead is generated due to the fusion of a conventional electric fusion joint and a resin pipe. (b) A diagram showing a state where a clevis is generated due to the fusion of a conventional electric fusion joint and a resin pipe.

Embodiments according to the present disclosure will be described below with reference to the drawings.

<Configuration>
(Summary of piping structure 100)
FIG. 1 shows an electric fusion joint 1 in an embodiment of the present disclosure, a resin pipe 11 (an example of a pipe containing thermoplastic resin) connected by the electric fusion joint 1, and a resin pipe 12 (an example of a pipe containing thermoplastic resin). FIG. FIG. 1 can also be said to be an exploded view of the piping structure 100. The piping structure 100 includes, for example, an electric fusion joint 1, a resin pipe 11, and a resin pipe 12.

As shown in the figure, the electric fusion joint 1 is fused to a resin pipe 11 and a resin pipe 12 to connect the resin pipe 11 and the resin pipe 12.

The resin pipe 11 and the resin pipe 12 are each made of thermoplastic resin. Specifically, resin pipe 11 and resin pipe 12 are made of polyolefin such as polyethylene.

The resin pipes 11 and 12 have flow passages 11f and 12f each having a circular cross section extending therein. The electric fusion joint 1 has a flow path 1f having a circular cross section extending therein. When the resin pipes 11 and 12 are connected by the electric fusion joint 1, the axes of the flow paths of the resin pipes 11, 12, and the electric fusion joint 1 are arranged on the same straight line.

Note that the direction in which the axes of the electric fusion joint 1, the resin pipe 11, and the resin pipe 12 extend with respect to the flow paths is defined as the axial direction A. Further, in the electric fusion joint 1, the resin pipe 11, and the resin pipe 12, the direction in which they approach and separate from each other perpendicular to their respective axes is defined as a radial direction B, and the direction in which they rotate around their respective axes is defined as a circumferential direction C.

The resin pipe 11 is connected to the electric fusion joint 1 by moving relative to the electric fusion joint 1 in the direction of arrow A1 in the axial direction A. Further, the resin pipe 12 is connected to the electric fusion joint 1 by moving relative to the electric fusion joint 1 in the arrow A2 direction in the axial direction A. A state in which resin pipes 11 and 12 are fused and connected to electric fusion joint 1 constitutes piping structure 100 .

(Electric fusion joint 1)
FIG. 2 is a diagram showing a cross-sectional configuration of the electric fusion joint 1. As shown in FIG.

As shown in FIGS. 1 and 2, the electric fusion joint 1 includes a main body portion 2, socket heat generating portions 3 and 4, a stopper heat generating portion 5, and a connector mounting portion 6.

(Main body part 2)
The main body part 2 is made of thermoplastic resin, and has a cylindrical part 21 and a stopper part 22, as shown in FIG. The cylindrical part 21 has a cylindrical shape and includes a joint socket part 23 , a joint socket part 24 , and a continuous part 25 . The resin pipe 11 is inserted inside the joint socket 23 . The resin pipe 12 is inserted inside the joint socket 24 .

The thermoplastic resin used in the main body portion 2 is not particularly limited, but one having a melting point of less than 230° C. is preferable.

FIG. 3 is a cross-sectional configuration diagram showing a state in which the resin pipe 11 is inserted inside the joint socket part 23 of the electric fusion joint 1, and the resin pipe 12 is inserted inside the joint socket part 24.

The inner diameter of the joint socket part 23 is formed to be larger than the outer diameter of the resin pipe 11. Further, the inner diameter of the joint socket portion 24 is formed to be larger than the outer diameter of the resin pipe 12. In addition, when the outer diameter of the resin pipe 11 is larger than the inner diameter of the joint socket part 23, the resin pipe 11 can be inserted into the joint socket part 23 by scraping the outer periphery of the resin pipe 11 with a scraper or the like. . Furthermore, if the outer diameter of the resin pipe 12 is larger than the inner diameter of the joint socket 24, the resin pipe 12 can be inserted into the joint socket 23 by scraping the outer periphery of the resin pipe 12 with a scraper or the like. . In this embodiment, the inner diameters of the joint socket part 23 and the joint socket part 24 are the same, and are indicated by d1 in FIG. 2 .

The connecting portion 25 is continuous with the joint socket portion 23 and the joint socket portion 24 as shown in FIG. 2, and connects the joint socket portion 23 and the joint socket portion 24. The continuous portion 25 is a portion that connects the joint socket portion 23 and the joint socket portion 24, and a stopper portion 22, which will be described later, is provided on the inside in the radial direction B.

(Stopper part 22)
The stopper portion 22 is an annular portion. The stopper portion 22 is formed on the inner surface 21a of the cylindrical portion 21 along the circumferential direction C in the form of a protrusion over the entire circumference. The stopper portion 22 also contains a thermoplastic resin, and is preferably formed of the same thermoplastic resin as the thermoplastic resin used in the cylindrical portion 21 .

The stopper portion 22 is formed to protrude radially inward from the inner surface 21a of the cylindrical portion 21. Further, the stopper portion 22 is arranged inside the continuous portion 25 of the cylindrical portion 21 in the radial direction B. Note that the stopper portion 22 may be formed as one member with the cylindrical portion 21, or may be formed as a separate member from the cylindrical portion 21.

The stopper portion 22 has a first side surface 22a, a second side surface 22b, and a peripheral surface 22c. The peripheral surface 22c is a radially inner end surface of the stopper portion 22.

The first side surface 22a is a side surface of the stopper portion 22 on the joint socket portion 23 side. The first side surface 22a is formed substantially perpendicular to the axial direction A toward the inside in the radial direction B from the inner surface 21a of the cylindrical portion 21.

The second side surface 22b is a side surface of the stopper portion 22 on the joint socket portion 24 side. The second side surface 22b is formed substantially perpendicular to the axial direction A toward the inside in the radial direction B from the inner surface 21a of the cylindrical portion 21.

The circumferential surface 22c connects the radially inner end of the first side surface 22a and the radially inner end of the second side surface 22b. The peripheral surface 22c is formed generally parallel to the inner surface 21a of the cylindrical portion 21.

FIG. 4 is an enlarged view of the stopper portion 22 and its vicinity. As shown in FIG. 4, if an imaginary surface connecting the inner surface 21a of the joint socket part 23 and the inner surface 21a of the joint socket part 24 is S3, the stopper part 22 of the main body part 2 is located on the inner side of the imaginary surface S3. It is a part. Further, if a virtual surface in which the first side surface 22a extends in the radial direction B is S1, and a virtual surface in which the second side surface 22b is extended in the radial direction B is S2, the continuous portion 25 is formed on the virtual surface of the main body portion 2. This is a portion surrounded by S1, virtual surface S2, and virtual surface S3.

The height of the stopper portion 22 from the inner surface 21a is indicated by h, and the width of the stopper portion 22 along the axial direction A is indicated by w.

When the resin pipe 11 is inserted inside the joint socket part 23, the pipe end 11a of the resin pipe 11 comes into contact with the first side surface 22a of the stopper part 22, as shown in FIG. is regulated. Note that the tube end 11a contacts the first side surface 22a when the tube end 11a directly contacts the first side surface 22a, and when the tube end 11a contacts the first side surface 22a through the heating wire 51 (described later) of the stopper heat generating section 5. This includes the case of indirectly contacting one side surface 22a.

When the resin pipe 12 is inserted inside the joint socket part 24, the pipe end 12a of the resin pipe 12 comes into contact with the second side surface 22b of the stopper part 22, as shown in FIG. is regulated. Note that the tube end 12a contacts the second side surface 22b when the tube end 12a directly contacts the second side surface 22b, and when the tube end 12a contacts the second side surface 22b through the heating wire 51 (described later) of the stopper heat generating section 5. This includes the case where the second side surface 22b is indirectly contacted.

In this embodiment, the resin pipes 11 and 12 have the same size, and in FIG. 3, the outer diameters of the resin pipes 11 and 12 are indicated by d2, and the wall thicknesses are indicated by d3.

The height h of the stopper portion 22 protruding from the inner surface 21a is 20% or more and 80% or less of the wall thickness d3 of the inserted tube. If the height h of the stopper part 22 exceeds 80% of the wall thickness d3 of the resin pipes 11 and 12, the stopper part 22 will melt after the start of fusion, and the heating wire will melt when the resin pipes 11 and 12 are pushed in. 51 may protrude onto the inner surfaces of the resin tubes 11 and 12, and if metal is exposed on the inner surfaces of the resin tubes, it cannot be used in the field of ultrapure water, which will be described later, which is not preferable.

Furthermore, if the height h of the stopper portion 22 is less than 20% of the wall thickness d3 of the resin tubes 11 and 12, the portions 11ap and 12ap ( (see FIG. 3) may not be sufficiently heated, resulting in insufficient fusion of the tube ends and the possibility of clevis formation, which is undesirable.

Furthermore, if the volume of the stopper portion 22 of the electrical fusion joint 1 of this embodiment is V, and the product of the cross-sectional area and wall thickness d3 of the resin pipes 11 and 12 is P, then V<P is satisfied. Note that the cross-sectional area of the resin pipes 11 and 12 is an annular portion having a wall thickness d3, and from the outer diameter d2 and the wall thickness d3, ((d2)/2) ² π-((d2-2×d3) /2) It can be found by ² π.

Further, as shown in the examples described later, it is preferable that 0.21≦V/P≦0.74 be satisfied.

(Socket heating parts 3, 4)
The socket heat generating parts 3 and 4 are provided in the joint socket parts 23 and 24.

The socket heat generating part 3 has a heating wire 31 embedded in the inner surface 21a of the joint socket part 23 which is one end of the cylindrical part 21, as shown in FIG.

The heating wire 31 is arranged so as to be wound two times in the circumferential direction along the inner surface 21a. The heating wire 31 is placed near the inner surface 21a. In addition, the heating wire 31 may be buried in the cylindrical part 21 so that a part is exposed to the flow path 1f side, or may be completely buried.

The socket heat generating part 4 has a heating wire 41 embedded in the inner surface 21a of the joint socket part 24, which is the other end of the cylindrical part 21, as shown in FIG.

The heating wire 41 is arranged so as to be wound two times in the circumferential direction along the inner surface 21a. The heating wire 41 is arranged near the inner surface 21a. In addition, the heating wire 41 may be buried in the cylindrical part 21 so that a part is exposed to the flow path 1f side, or may be completely buried.

The heating wire 31 includes, for example, a conducting wire 31a and an insulating film 31b. The heating wire 41 may include, for example, a conducting wire 41a and an insulating film 41b. As the conductive wires 31a and 41a, for example, a nichrome wire, an iron chrome type 2 wire, an iron chrome type 1 wire, a nickel chrome wire, etc. can be used. The wire diameter of the conducting wires 31a and 41a can be set to, for example, φ0.3 to 0.8 mm. If the diameter is less than 0.3 mm, the wire may expand due to the tension during winding and the resistance value may become unstable. Further, the resistance value per unit length of the conducting wires 31a and 41a is about 2 to 21 Ω/m depending on the wire diameter.

The insulating films 31b and 41b are provided to cover the periphery of the conductive wire. The insulating films 31b and 41b have a melting point of 230 degrees or higher. This is preferably set at a temperature at which the thermoplastic resin in this embodiment melts (for example, in the case of polyethylene, the heating wire heats up to 220 degrees), but at which it does not melt. The insulating films 31b and 41b can be formed of, for example, fluororesin or imide resin, but it is more preferable to form them of polyimide resin. For example, the thickness of the conducting wires 31a and 41a may be set to 0.1 mm or more and 10 mm or less. Note that the heating wires 31 and 41 do not need to have the insulating coatings 31b and 41b.

The socket heat generating part 4 is provided symmetrically with respect to the socket heat generating part 3 and the stopper part 22 as a reference. The socket heat generating part 3 is configured by being wound two times along the axial direction A so that the heating wire 31 contacts the joint socket part 23 . The socket heat generating part 4 is configured so that the heating wire 41 is wound two times along the axial direction A so that the heating wire 41 contacts the joint socket part 24 .

As shown in FIG. 2, in the axial direction A, the socket heat generating part 3 is arranged adjacent to the stopper part 22. Further, in the axial direction A, the socket heat generating part 4 is arranged adjacent to the stopper part 22. Specifically, as shown in FIG. 2, the heating wire 31 of the socket heating section 3 closest to the stopper section 22 is placed in contact with a virtual surface S1 extending the first side surface 22a in the radial direction B. 31 is arranged. In addition, as shown in FIG. 2, the heating wire 41 is arranged so that the heating wire 41 closest to the stopper part 22 of the socket heat generating part 4 is in contact with a virtual plane S2 extending the second side surface 22b in the radial direction B. has been done.

(Stopper heat generating part 5)
The stopper heat generating part 5 is provided in the stopper part 22. The stopper heat generating section 5 has a heating wire 51. The heating wire 51 is provided on the stopper portion 22 so as to be wound in the circumferential direction C along the axial direction A. In this embodiment, the heating wire 51 is wound around the stopper portion 22, for example, four times. In the stopper heat generating section 5 of this embodiment, all adjacent heating wires 51 are in contact with each other.

Although the heating wire 51 is embedded in the stopper portion 22, it may be buried in the stopper portion 22 so that a portion thereof is exposed from the first side surface 22a, the second side surface 22b, or the circumferential surface 22c to the flow path 1f side. good.

For example, as shown in FIG. 2, the heating wire 51 includes a conducting wire 51a and an insulating film 51b. As the conducting wire 51a, for example, a nichrome wire, an iron chrome type 2 wire, an iron chrome type 1 wire, a nickel chrome wire, etc. can be used. The wire diameter of the conducting wire 51a can be set to φ0.3 to 0.8 mm. If the diameter is less than 0.3 mm, the wire may expand due to the tension during winding and the resistance value may become unstable. Due to the equipment for forming the insulating film 51b, the wire diameter of the conducting wire 51a is set to a maximum of 0.8 mm. Further, the resistance value per unit length of the conducting wire 51a is about 2 to 21 Ω/m depending on the wire diameter.

The insulating film 51b is provided to cover the periphery of the conductive wire 51a. The insulating film 51b has a melting point of 230 degrees or higher. This is preferably set at a temperature at which the thermoplastic resin in this embodiment melts (for example, in the case of polyethylene, the heating wire heats up to 220 degrees), but at which it does not melt. The insulating film 51b can be formed of, for example, a fluororesin or an imide resin, but it is more preferably formed of a polyimide resin. For example, the thickness of the conducting wire 51a may be set to 0.1 mm or more and 10 mm or less. Note that the heating wire 51 does not need to have the insulating film 51b.

In the present embodiment, one heating wire 51 is wound four times in the stopper heating section 5 so as to be in contact with its neighbor; however, the present invention is not limited to this. It may be. Moreover, the stopper heat generating part 5 may be formed by winding not only one heating wire 51 but two or more heating wires 51 . The heating wire 51 may be wound so that all or part thereof does not come into contact with the adjacent wire.

(Connector mounting part 6)
The connector attachment part 6 has two pins 61, as shown in FIG. The two pins 61 are provided so as to protrude radially outward from the outer surface 21d of the cylindrical portion 21. As shown in FIG. 2, one of the two pins 61 is arranged near the end 21b of the cylindrical portion 21, and the other pin 61 is arranged near the end 21c. Although not shown, the two pins 61 are connected to the heating wires 31 and 41 of the socket heating parts 3 and 4 and the heating wire 51 of the stopper heating part 5. When a connector of an electric fusion device is attached to the pin 61 and energized, the heating wires 31, 41, and 51 generate heat. In this embodiment, the heating wires 31, 41, and 51 are connected and constitute a single heating wire.

<Jig 200>
Next, a jig 200 used in the connection method according to the embodiment of the present disclosure will be described. The resin pipe 11, the electric fusion joint 1, and the resin pipe 12 are arranged on the jig 200. FIG. 5 is a diagram showing the jig 200. FIG. 6 is a diagram showing a state in which the resin pipe 11, the electric fusion joint 1, and the resin pipe 12 are attached to the jig 200. FIG. 7 is a side view of FIG. 6.

The jig 200 includes a first clamp section 210, a second clamp section 220, a shaft section 230, a pressing section 240, a regulating section 250, and a pedestal 260.

(pedestal 260)
Pedestal 260 is a plate-shaped member. The pedestal 260 supports the first clamp part 210, the second clamp part 220, the shaft part 230, the pressing part 240, and the regulating part 250, which are arranged on the upper surface side.

(First clamp part 210)
The first clamp part 210 clamps and fixes the resin pipe 11. The first clamp section 210 includes a lower clamp section 211 , an upper clamp section 212 , a hinge section 213 , a fastening section 214 , and a bearing section 215 . The lower clamp portion 211 is a member having a semicircular recess 211a formed on its upper surface. In this embodiment, the lower clamp portion 211 is a generally rectangular parallelepiped-shaped member with a semicircular recess formed in the upper surface.

The bearing portion 215 is provided on the lower clamp portion 211. The bearing portion 215 is inserted into a through hole formed in the lower clamp portion 211. The bearing portion 215 is arranged below the recess 211a. A shaft portion 230, which will be described later, is inserted inside the bearing portion 215. The axial direction of the bearing portion 215 is arranged parallel to the central axis of the recessed portion 211a. Thereby, the first clamp section 210 can move along the shaft section 230. When the resin pipe 11, the resin pipe 12, and the electric fusion joint 1 are placed on the jig, the axial direction of the bearing portion 215 is parallel to the axial direction A.

The upper clamp portion 212 is a member in which a semicircular recess 212a is formed. In this embodiment, the upper clamp portion 212 is a generally rectangular parallelepiped-shaped member with a semicircular recess 212a formed on one predetermined surface.
The upper clamp part 212 and the lower clamp part 211 can sandwich the outer periphery of the resin pipe 11 between the recess 212a and the recess 211a formed therein. The central axes of the recess 212a and the recess 211a substantially coincide with each other when the resin pipe 11 is sandwiched between them. Moreover, in the state where the resin tube 11 is sandwiched, this central axis coincides with the axial direction A mentioned above.

The hinge portion 213 rotatably connects the ends of the lower clamp portion 211 and the upper clamp portion 212 to each other. The upper clamp part 212 is configured to be rotatable with respect to the lower clamp part 211 about the hinge part 213 . The upper clamp part 212 is attached to the lower clamp part 211 via the hinge part 213 so that when the upper clamp part 212 rotates around the hinge part 213, the recess 212a thereof faces the recess 211a of the lower clamp part 211. There is.

The resin pipe 11 is arranged along the recess 211a of the lower clamp part 211 with the hinge part 213 as the center and the space between the lower clamp part 211 and the upper clamp part 212 is open. Thereafter, the upper clamp part 212 rotates around the hinge part 213, and the resin pipe 11 is arranged so as to fit into the recess 212a.

The fastening portion 214 is a so-called snap lock. The fastening portion 214 includes a lock body 214a and a protrusion 214b. The fastening portion 214 is provided on the opposite side of the hinge portion 213 with the recesses 211a and 212a of the lower clamp portion 211 and the upper clamp portion 212 interposed therebetween. The lock body 214a is arranged on the side surface of the lower clamp section 211, and the protrusion 214b is arranged on the side surface of the upper clamp section 212. The lock body 214a includes a lever 214c and an annular portion 214d. With the upper clamp part 212 rotated above the lower clamp part 211, the annular part 214d is hooked on the protrusion 214b and the lever 214c is tilted downward. can be fastened in the closed state.

(Second clamp part 220)
The second clamp part 220 clamps and fixes the resin pipe 12. The second clamp part 220 fixes the resin tube 12 so that the center axis of the resin tube 12 coincides with the center axis of the resin tube 11.

The second clamp section 220 includes a lower clamp section 221 , an upper clamp section 222 , a hinge section 223 , and a fastening section 224 . The lower clamp portion 221 is a member having a semicircular recess 221a formed in its upper surface. In this embodiment, the lower clamp portion 221 is a generally rectangular parallelepiped-shaped member with a semicircular recess formed in the upper surface. Lower clamp portion 211 is fixed to pedestal 260 via bracket 270.

The upper clamp portion 222 is a member in which a semicircular recess 222a is formed. In this embodiment, the upper clamp portion 222 is a generally rectangular parallelepiped member having a semicircular recess 222a formed on one predetermined surface.
The upper clamp part 222 and the lower clamp part 221 can sandwich the outer periphery of the resin pipe 12 between the recess 222a and the recess 221a formed therein. The central axes of the recess 222a and the recess 221a substantially coincide with each other when the resin pipe 12 is sandwiched therebetween. Moreover, in the state where the resin tube 12 is sandwiched, this central axis coincides with the axial direction A mentioned above.

The hinge portion 223 rotatably connects the ends of the lower clamp portion 221 and the upper clamp portion 222. The upper clamp part 222 is configured to be rotatable with respect to the lower clamp part 221 about the hinge part 223 . The upper clamp part 222 is attached to the lower clamp part 221 via the hinge part 223 so that when the upper clamp part 222 rotates around the hinge part 223, the recess 222a thereof faces the recess 221a of the lower clamp part 221. There is.

The resin pipe 12 is arranged along the recess 221a of the lower clamp part 221 with the hinge part 223 as the center and the lower clamp part 221 and the upper clamp part 222 open. Thereafter, the upper clamp part 222 rotates around the hinge part 223, and the resin pipe 12 is arranged so as to fit into the recess 222a.

The fastening portion 224 is a so-called snap lock. The fastening portion 224 includes a lock body 224a and a protrusion 224b. The fastening portion 224 is provided on the opposite side of the hinge portion 223 with the recesses 221a and 222a of the lower clamp portion 221 and the upper clamp portion 222 interposed therebetween. The lock body 224a is arranged on the side surface of the lower clamp section 221, and the protrusion 224b is arranged on the side surface of the upper clamp section 222. The lock body 224a includes a lever 224c and an annular portion 224d. With the upper clamp part 222 rotated above the lower clamp part 221, the annular part 224d is hooked on the protrusion 224b and the lever 224c is tilted downward, so that the upper clamp part 222 is rotated relative to the lower clamp part 221. can be fastened in the closed state.

With the resin pipe 11 and the resin pipe 12 inserted into the electric fusion joint 1, the resin pipe 11 is held between the first clamp part 210 and the resin pipe 12 is held between the second clamp part 220, so that the resin is attached to the jig 200. The pipe 11, the resin pipe 12, and the electric fusion joint 1 can be arranged.

(Shaft portion 230)
The shaft portion 230 is supported by a pedestal 260. The shaft portion 230 is arranged parallel to the central axes of the recess 211a and the recess 212a of the first clamp portion 210. The shaft portion 230 is arranged parallel to the central axes of the recess 221a and the recess 222a of the second clamp portion 220. Further, the shaft portion 230 is arranged parallel to the central axes of the resin tube 11 fixed to the first clamp portion 210 and the resin tube 12 fixed to the second clamp portion 220. The shaft portion 230 is arranged along the axial direction A mentioned above.

The shaft portion 230 extends from the second clamp portion 220 toward the first clamp portion 210 side. The first clamp section 210 is attached to the shaft section 230 so as to be movable along the shaft section 230 . The shaft portion 230 is arranged from the lower clamp portion 221 to the lower clamp portion 211. A bearing portion 215 is disposed below the recess 211a of the lower clamp portion 211 of the first clamp portion 210, and the shaft portion 230 is inserted through the bearing portion 215.

(Press section 240)
The pressing section 240 presses the first clamp section 210 along the shaft section 230 toward the second clamp section 220 side. The pressing portion 240 includes a spring 241 and a nut 242.

A spring 241 is disposed around the shaft portion 230 of the first clamp portion 210 on the opposite side from the second clamp portion 220 .

The nut 242 is arranged on the shaft portion 230 of the spring 241 on the opposite side from the first clamp portion 210. A male screw shape is formed around the end of the shaft portion 230 on the opposite side from the second clamp portion 220, and is screwed into a female screw shape formed inside the nut 242. Nut 242 is movable along shaft portion 230 by rotation.

The spring 241 is arranged between the nut 242 and the first clamp part 210. Since the nut 242 is screwed into the shaft portion 230 and its position on the shaft portion 230 is fixed, a load is applied to the first clamp portion 210 toward the second clamp portion 220 . The load can be set, for example, in the range of 1 to 50 kgf, and more preferably in the range of 3 to 20 kgf. In addition, when the nut 242 is rotated to approach the first clamp part 210 with the resin pipes 11 and 12 and the electric fusion joint 1 placed in the jig 200, the spring 241 is compressed. It is possible to increase the load applied to the On the other hand, when the nut 242 is rotated and moved away from the first clamp part 210, the spring 241 expands, so that the load applied to the first clamp part 210 can be reduced.

Note that, as shown in FIG. 7, with the resin pipe 11, the resin pipe 12, and the electric fusion joint 1 arranged in the jig 200, a load is applied to the first clamp part 210 by the pressing part 240, so that the resin pipe 11 A load is applied to the tube end 11a of the resin tube 12 and the tube end 12a of the resin tube 12 so as to be pressed against the stopper portion 22.

(Regulation Department 250)
The restricting portion 250 restricts the first clamp portion 210 from being moved too much toward the second clamp portion 220 by the pressing portion 240 .

The regulating section 250 is arranged between the first clamp section 210 and the second clamp section 220.

The regulating part 250 has a fixing part 251 and an abutting part 252. The fixed part 251 is fixed to a pedestal 260. The contact portion 252 is a portion extending upward from the fixed portion 251 and is disposed around the shaft portion 230 . By abutting the bearing portion 215 of the first clamp portion 210 against the contact portion 252, it is possible to restrict further movement of the first clamp portion 210 toward the second clamp portion 220 side.

<Connection method>
Next, a connection method using the jig 200 described above will be explained. FIG. 8 is a flow diagram showing the connection method of this embodiment.

First, in step S1, the resin pipe 11 and the resin pipe 12 are inserted into the electric fusion joint 1. As shown in FIG. 3, the resin pipe 11 is inserted inside the joint socket part 23 of the electrofusion joint 1 until the relative movement of the pipe end 11a of the resin pipe 11 is regulated by the stopper part 22. . Next, the resin pipe 12 is inserted inside the joint socket part 24 of the electrofusion joint 1 until the relative movement of the pipe end 12a of the resin pipe 12 is restricted by the stopper part 22. FIG. 3 shows a state in which the resin pipes 11 and 12 are inserted into the electric fusion joint 1. Note that it is more preferable to scrape the end faces (faces facing the stopper portion 22) of the resin pipes 11 and 12 before inserting them into the electric fusion joint 1 before step S1, since this improves the strength of the fusion bond.

In this state, in step S2 (an example of the arrangement step), as shown in FIGS. 6 and 7, the resin pipe 11 is clamped and fixed by the first clamp part 210, and the resin pipe 12 is clamped and fixed by the second clamp part 220. The resin pipe 11, the electric fusion joint 1, and the resin pipe 12 are placed on the jig 200.

By fixing the resin pipe 11, the electric fusion joint 1, and the resin pipe 12 to the jig 200, the second clamp is attached to the first clamp part 210 by the urging force of the pressing part 240 in step S3 (an example of a pressurizing step). A load is applied toward the portion 220. By applying the load from the first clamp section 210 toward the second clamp section 220, the tube end 11a of the resin tube 11 is pressed against the first side surface 22a of the stopper section 22, and the tube end 12a of the resin tube 12 is pressed against the first side surface 22a of the stopper section 22. It is pressed against the second side surface 22b.

Next, in step S4 (an example of a heating step), the connector of the electrofusion device is attached to the two pins 61 of the connector attachment part 6 in a pressurized state, and electricity is applied for a predetermined period of time.

This energization generates heat in the heating wire 51, and the stopper portion 22, the tube end 11a of the resin tube 11, and the tube end 12a of the resin tube 12 are melted and brought into close contact with the stopper portion 22.

Note that by energizing, the stopper part 22 melts and the width in the axial direction A becomes smaller, thereby reducing the applied load. The load applied to the portion 210 can be secured. Although it is desirable that the load does not change even if the tube ends 11a and 12a melt, it may change.

The temperature of the heating wire during energization may be a temperature that melts the main body portion 2, and in the case of polyolefin, it is preferably 220 degrees or less.

Next, in step S5 (an example of a cooling step), the melted resin pipe 11, electric fusion joint 1, and resin pipe 12 are cooled for a predetermined period of time. Note that it is preferable to continue applying the load by the pressing section 240 until step S5 is completed.

FIG. 9 is a diagram showing a state in which the resin pipe 11, the electric fusion joint 1, and the resin pipe 12 are melted and connected. As shown in FIG. 9, the stopper portion 22 is melted and narrowed by being pushed by the resin pipes 11 and 12, filling the space between the resin pipes 11 and 12, and forming a bead R.

FIG. 10(a) is a schematic diagram showing the resin pipes 11, 12 and the stopper part 22. FIG. 10(b) is a schematic diagram showing the resin pipes 11, 12 and the stopper portion 22 after being melted and connected. In FIG. 10(b), the remaining portion of the stopper portion 22 remaining after melting is indicated by 22p. FIG. 10(c) shows the remaining portion 22p of the stopper portion 22 and the remaining portion 22q. As shown in FIG. 10(c), a compensation portion 22q other than the remaining portion 22p of the stopper portion 22 compensates for a gap D surrounded by the melted resin pipe 11, the resin pipe 12, and the remaining portion 22p. The gap D is a space formed by the height from the height of the stopper part 22 before fusion to the inner peripheral surface of the resin pipes 11 and 12, and the width between the resin pipes 11 and 12 after fusion. It is.

Gap D is shown in FIG. 10(d). In FIG. 10(d), the gap D is shown filled in. Here, in order to form a bead R that bulges inward from the inner peripheral surfaces of the resin pipes 11 and 12, the volume Vq of the compensation portion 22q is set larger than the volume Vd of the gap D. For example, it is preferable that the gap filling rate expressed by volume Vq of filling portion 22q/volume Vd of gap D×100 (%) is set to 120 to 300%. Note that the length of the remaining portion 22p along the axial direction A (see FIG. 10(b)) is, for example, a quarter of the width W of the original stopper portion 22, and is, for example, 1 mm. .

Note that the volume of the annular stopper portion 22 is V, and the volume of the annular remaining portion 22p within the width W' of the stopper portion 22 is Vp. The volume V of the stopper portion 22 is the sum of the volume Vp of the remaining portion 22p and the volume Vq of the supplementary portion 22q. Further, the volume of the portion sandwiched between the thicknesses of the resin pipes 11 and 12 after fusion is assumed to be V'. The volume V' is the sum of the volume Vd of the gap D and the volume Vq of the remaining portion 22p in FIG. 10(d).

In this case, the volume Vq of the supplementary portion 22q can be expressed as V-Vp, and the volume Vd of the gap D can be expressed as V'-Vp. Therefore, the void filling rate can be expressed as (V-Vp)/(V'-Vp)×100(%), and this value is 120% or more and 300% or less.

Note that if the void filling rate is greater than 300%, the bead will become too large, and if it is less than 120%, the void will not be completely filled. Therefore, by setting the void filling rate to 120% or more and 300% or less, you can stably maintain the bead. water can be formed and water retention can be suppressed.

<Ultra pure water application of piping structure 100>
The piping structure 100 according to the embodiment of the present disclosure can be used, for example, to transport ultrapure water. Specifically, the piping structure 100 for ultrapure water according to the embodiment of the present disclosure includes piping within an ultrapure water production device, piping that transports ultrapure water from the ultrapure water production device to a point of use, and It can be used as ultrapure water return piping from the point of use.

Ultrapure water is water with extremely high purity, and is suitably used for cleaning electronic equipment such as semiconductor devices, for example. There are many indicators for expressing the grade of ultrapure water, but in this embodiment, the electrical resistivity of ultrapure water is 18.2 MΩ·cm or more, and the TOC is 50 ppb or less.

The piping structure 100 according to the embodiment of the present disclosure is suitable for use in water piping for nuclear power generation, where the required water quality for ultrapure water is particularly strict, or in the manufacturing process of pharmaceuticals, semiconductor elements or liquid crystals, and more preferably in the manufacturing process of semiconductor elements. Preferably, it is a pipe for transporting ultrapure water used in wet processing steps such as cleaning. The semiconductor element also preferably has a higher degree of integration, and specifically, it is more preferable to use it in the manufacturing process of a semiconductor element with a minimum line width of 65 nm or less. Examples of standards regarding the quality of ultrapure water used in semiconductor manufacturing include SEMI F75.

Moreover, since the piping structure 100 of the embodiment according to the present disclosure has a polyethylene resin layer, it has excellent workability. For example, fusion bonding such as EF (electrofusion) bonding can be easily performed at relatively low temperatures.

<Features>
The electric fusion joint 1 of this embodiment includes a cylindrical portion 21, a stopper portion 22, socket heat generating portions 3 and 4, and a stopper heat generating portion. The cylindrical portion 21 has a cylindrical shape and has joint socket portions 23 and 24 into which resin pipes 11 and 12 containing thermoplastic resin can be inserted. The stopper part 22 is provided on the inner surface 21a of the cylindrical part 21 so as to protrude inward, and stops the resin pipes 11 and 12 when the resin pipes 11 and 12 are inserted inside the joint socket parts 23 and 24. The insertion positions of the ends 11a and 12a can be regulated. The socket heat generating parts 3 and 4 have heating wires 31 and 41 arranged at the joint socket part. The stopper heat generating part 5 is. It has a heating wire 51 coated with an insulator and placed in the stopper part 22. The height h of the stopper portion 22 protruding from the inner surface 21a is 20% or more and 80% or less of the wall thickness d3 of the inserted tube. If the volume of the stopper portion 22 is V, and the product of the cross-sectional area and wall thickness d3 of the resin tubes 11 and 12 is P, then V<P is satisfied.

The bead is formed by melting the resin of the stopper portion 22 and the resin on the surfaces of the tube ends 11a and 12a, so the size of the stopper portion 22 is adjusted to match the dimensions of the tube ends 11a and 12a, which vary depending on the size of the resin tubes 11 and 12. By appropriately setting the dimensions, beads can be stably formed and water retention can be suppressed.

The height h of the stopper portion 22 protruding from the inner surface 21a is 20% or more and 80% or less of the wall thickness d3 of the inserted tube. If the height h of the stopper part 22 exceeds 80% of the wall thickness d3 of the resin pipes 11 and 12, the stopper part will melt after the start of fusion and the heating wire 51 will melt when the resin pipes 11 and 12 are pushed in. There is a possibility that the water may jump out onto the inner surfaces of the resin tubes 11 and 12, and this is not preferable because it cannot be used in the field of ultrapure water, which will be described later.

Furthermore, if the height h of the stopper portion 22 is less than 20% of the wall thickness d3 of the resin tubes 11 and 12, the portions 11ap and 12ap ( (see FIG. 3) may not be sufficiently heated, resulting in insufficient fusion of the tube ends and the possibility of clevis formation, which is undesirable.

Thereby, beads can be stably formed and water retention can be suppressed.

The electric fusion joint 1 of this embodiment includes a cylindrical portion 21, a stopper portion 22, socket heat generating portions 3 and 4, and a stopper heat generating portion 5. The cylindrical part 21 has a pair of joint socket parts 23 and 24 into which resin pipes 11 and 12 containing thermoplastic resin can be inserted. It is provided so as to protrude inward from the inner surface 21a of the cylindrical part 21, and when the resin pipes 11, 12 are inserted inside the respective joint socket parts 23, 24, the pipe ends of each resin pipe 11, 12 The insertion positions of 11a and 12a are regulated. The socket heat generating parts 3 and 4 have heating wires 31 and 41 arranged in the joint socket parts 23 and 24, respectively. The stopper heat generating section 5 includes a heating wire 51 coated with an insulator and disposed on the stopper section 22 . The height h of the stopper portion 22 protruding from the inner surface 21a is 20% or more and 80% or less of the wall thickness of the resin pipes 11 and 12 to be inserted. The volume of the stopper part 22 is V, the volume of the volume V of the stopper part 22 in the width range along the axis of the stopper part 22 after welding is Vp, and the wall thickness of the resin pipes 11 and 12 after welding. When the volume of the portion sandwiched by d3 is V', (V-Vp)/(V'-Vp)×100 (%) is 120% or more and 300% or less.

Since the bead R is formed by melting the resin of the stopper part 22 and the resin of the tube ends 11a and 12a, the dimensions of the stopper part 22 are adjusted to match the dimensions of the tube ends 11a and 12a, which vary depending on the size of the resin tubes 11 and 12. By setting appropriately, the bead R can be stably formed and water retention can be suppressed.

Note that if the height of the stopper part 22 exceeds 80% of the wall thickness of the resin pipes 11 and 12, the stopper part 22 will melt after the start of fusion and the stopper part 22 will melt when the resin pipes 11 and 12 are pushed in. There is a possibility that the heating wire 51 of No. 22 will jump out onto the inner surface of the resin tubes 11 and 12. If the heating wire 51 is exposed, it is not preferable because the electric fusion joint 1 of this embodiment cannot be used in the field of pure water. In addition, if the height of the stopper part 22 is less than 20% of the wall thickness of the resin pipes 11, 12, the portions of the pipe ends 11a, 12a near the inner circumferential surfaces of the resin pipes 11, 12 will be sufficient during fusion. This is not preferable since the tube ends 11a and 12a may not be heated properly, resulting in insufficient fusion bonding between the tube ends 11a and 12a, which may result in crevices.

Therefore, by setting the height h protruding from the inner surface 21a of the stopper part 22 to 20% or more and 80% or less of the wall thickness of the inserted pipe, the occurrence of clevises can be suppressed and the bead can be stably formed. water can be formed and water retention can be suppressed.

Furthermore, if the value of (V-Vp)/(V'-Vp)×100(%) is larger than 300%, the bead becomes too large, and if it is smaller than 120%, the voids cannot be completely filled.

Therefore, by setting (V-Vp)/(V'-Vp)×100(%) to 120% or more and 300% or less, bead R can be stably formed and water retention can be suppressed. .

In the electric fusion joint 1 of this embodiment, V and P satisfy 0.21<V/P<0.74.

Thereby, beads can be stably formed and water retention can be suppressed.

<Other embodiments>
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various changes can be made without departing from the gist of the invention.

(A)
FIG. 11A is a partially enlarged view of the vicinity of the stopper portion 22 of the electric fusion joint 101 according to a modification of the present embodiment. FIG. 11A shows a thick portion of the resin pipe 11 inserted into the electric fusion joint 101. Similarly, FIGS. 11(b), 12(a), and 12(b) shown below are partially enlarged views of the vicinity of the stopper portion 22, and show the thick portion of the resin pipe 11.

As shown in the electric fusion joint 101 shown in FIG. 11(a), a step 21g may be formed in the portion where the socket heat generating parts 3 and 4 are arranged. Due to the formation of the step 21g, the inner surface 21a has an inner surface 21ag extending along the axial direction A of the step 21g, and an inner surface 21ah extending along the axial direction A closer to the ends 21b and 21c than the inner surface 21ag. The inner surface portion 21ag is located inside the inner surface portion 21ah. The socket heat generating parts 3 and 4 are arranged inside the step 21g. The virtual surface S3 that separates the stopper portion 22 and the continuous portion 25 is a surface that connects the inner surface 21ag of the joint socket 23 and the inner surface 21ag of the joint socket 24. The resin pipes 11 and 12 are inserted inside the step 21g. In this case, the height h of the stopper portion 22 is a height that projects inward from the inner surface portion 21ag.

(B)
In the above embodiment, the socket heat generating parts 3 and 4 are arranged next to the stopper part 22 in the axial direction A so as to be in contact with the virtual surfaces S2 and S3, but the electric fusion joint shown in FIG. As shown at 102, it may be separated from the stopper part 22. The distance that the socket heat generating parts 3 and 4 are away from the stopper part 22 is shown as a distance L from the virtual surfaces S1 and S2.

(C)
In the above embodiment, the heating wires 51 are arranged adjacent to each other in the direction along the width w of the stopper portion 22, but as shown in the electric fusion joint 103 in FIG. 12(a), they are not adjacent to each other. It's okay. Further, the number of turns of the heating wire 51 in the stopper heat generating part 5 does not have to be limited to four turns.

In the electric fusion joint 103 shown in FIG. 12(a), the heating wires 51 are not lined up next to each other in the stopper heating section 5 disposed in the stopper section 22, and there is a gap between the adjacent heating wires 51. It is provided. In addition, it is not necessary to provide an interval between all the heating wires 51, and only some of them do not need to be in contact with each other. Further, in the electric fusion joint 103, the number of windings of the heating wire 51 in the stopper heat generating portion 5 is three.

(D)
In the above embodiment, the heating wire 51 is arranged so as to be in contact with the circumferential surface 22c of the stopper section 22, but as shown in the electric fusion joint 104 of FIG. 12(b), the circumferential surface 22c of the stopper section 22 It may be buried at a predetermined interval from the base.

(E)
In the first and second embodiments described above, the heating wires 31 and 41 are wound around two turns in contact with each other in each of the socket heat generating parts 3 and 4, but the number of turns is not limited to two turns. In addition, when it is wound three times or more, all or part of it does not have to be in contact with each other. Further, a plurality of portions may be provided with a predetermined number of adjacent portions.

(F)
In the embodiment described above, the socket heat generating part 3 and the socket heat generating part 4 are provided symmetrically with the stopper part 22 in between, but the invention is not limited to this. For example, the heating wire 31 may be wound two times around one joint socket 23 with the stopper part 22 in between, and the heating wire 31 may be wound three times around the other joint socket 24 .

(G)
In the embodiment described above, the flow paths of the electric fusion joint 1 are all formed in a straight line, but an elbow joint in which the flow paths are curved may also be used.

(H)
In the above embodiment, the heating wire 31 of the socket heating section 3, the heating wire 41 of the socket heating section 4, and the heating wire 51 of the stopper heating section 5 are constituted by one heating wire, but the invention is not limited to this. It is not necessary, and separate heating wires may be connected. Further, although all the heating wires 31, 41, and 51 are provided with an insulating film, the present invention is not limited to this. However, it is preferable that at least the heating wire 41 is provided with an insulating film. This is because the heating wires 41 are likely to come into contact with each other because they are pressurized by the resin pipes 11 and 12.

(I)
In the above embodiment, the resin tubes 11 and 12 are used as an example of the tube, but the present invention is not limited to this, and a tube made of resin such as a metal-reinforced composite tube having a metal reinforcement layer may be used.

(J)
In the first and second embodiments described above, the socket heating section 3 and the socket heating section 4 are heated at the same time, but a connector connection section is provided for each of the socket heating section 3 and the socket heating section 4. If so, either one of the socket heat generating part 3 and the socket heat generating part 4 may be heated before the other is heated.

(K)
In the first and second embodiments described above, the spring 241 and the nut 242 are used as the pressing part that applies a load to the first clamp part 210, but the spring 241 and the nut 242 are not limited to this, and a motor, cylinder, etc. There may be. Further, the pressure of the tube ends 11a and 12a against the stopper portion 22 may be based on either the addition of a load to the first clamp portion 210 or the amount of movement thereof.

Further, when applying a load using a motor or a cylinder, the control may be performed in conjunction with an electric fusion device. For example, the motor or cylinder may be controlled as the heating time by the electric fusion device elapses according to a preset program so that the load is maintained at a predetermined level or higher.

(Example)
The embodiments described above will be described in detail below using examples.

In the following Examples and Comparative Examples, the joint inner diameter d1 of the electric fusion joint 1 and resin pipes 11 and 12 (the same resin pipe 11 and resin pipe 12 are used) and the height of the stopper part 22 shown in FIG. h, the width w of the stopper part 22, the wall thickness d3 of the resin tubes 11 and 12, the outer diameter d2 of the resin tubes 11 and 12, and the inner diameter d4 of the heating wire as shown below (Table 1), The electric fusion joint 1 and the resin pipes 11 and 12 were fused together. The electric fusion joint 1 shown in FIG. 13 has a structure in which the step 21g shown in FIG. The inner diameter d1 indicates the inner diameter of the inner surface 2ah.

The material of the electric fusion joint 1 is olefin resin. The material of the resin pipes 11 and 12 is olefin resin. The heating wire 31 has an insulating film formed of an olefin resin such as imide or amide-imide. The diameter of the heating wire 31 is 0.3-2.0 mm.

In the Examples and Comparative Examples, the electrical fusion joint 1 and the resin pipes 11 and 12 were connected according to the flowchart of FIG. 7 described in the first embodiment.

The conditions for heating the tube ends 11a and 12a of the resin tubes 11 and 12 in FIG. 10(a) are to apply a heating time and voltage that exceeds 230 degrees (about 20-76V, 30-600S). The pressure at which the resin pipes 11 and 12 are bonded together is 0.15 MPa x the cross-sectional area of the resin pipes. The conditions for heating the socket heat generating parts 3 and 4 are to apply a heating time and voltage that exceeds 230 degrees.

The piping structures of the above examples and comparative examples were cut and visually checked to see if bead spouting or denting had occurred, and the bead condition was determined to be good (〇), within acceptable range (△), or poor (x). A judgment was made.

The results are shown in Table 1 below.
(Table 1)

If the volume of the stopper portion 22 is V, and the product of the cross-sectional area and wall thickness d3 of the resin tubes 11 and 12 is P, then from Examples 1 to 12 in Table 1 above, h/d3×100(%) is When 20% or more and 80% or less and V<P are satisfied, the shape of the bead is good or within an acceptable range.

Furthermore, as shown in Examples 1, 2, 4, 5 to 7, 11, and 12, it is more preferable to satisfy 0.21≦V/P≦0.74 because the shape of the bead becomes good.

In addition, the impact on quality is greater when h/d3×100 (%) is 20% or more and 80% or less, and if you deviate from this range, there is a high probability that the water quality will be poor, but if you deviate from V<P This will have less impact on water quality.

1 : Electrical fusion joint 3 : Socket heat generating part 4 : Socket heat generating part 5 : Stopper heat generating part 11 : Resin pipe 11a : Pipe end 12 : Resin pipe 12a : Pipe end 21 : Cylindrical part 21a : Inner surface 22 : Stopper Department

Claims (3)

a cylindrical part having a joint socket into which a tube containing a thermoplastic resin can be inserted;
a stopper part that is provided on the inner surface of the cylindrical part so as to protrude inward, and that restricts the insertion position of the pipe end of the pipe when the pipe is inserted inside the joint socket part;
a socket heating section having a heating wire disposed in the joint socket;
a stopper heating section having a heating wire disposed in the stopper section,
The height of the stopper portion protruding from the inner surface is 20% or more and 80% or less of the wall thickness of the tube to be inserted,
If the volume of the stopper part is V, and the product of the cross-sectional area of the tube and the wall thickness is P,
Electric fusion joint that satisfies V<P. a cylindrical part having a pair of joint socket parts into which a tube containing a thermoplastic resin can be inserted;
a stopper part that is provided to protrude inward on the inner surface of the cylindrical part and that regulates the insertion position of the pipe end of each of the pipes when the pipe is inserted inside each of the joint socket parts; ,
a socket heating section having a heating wire disposed in the joint socket;
a stopper heating section having a heating wire disposed in the stopper section,
The height of the stopper portion protruding from the inner surface is 20% or more and 80% or less of the wall thickness of the tube to be inserted,
The volume of the stopper part is V, the volume of the volume V of the stopper part in the width range along the axis of the stopper part after fusion is Vp, and When the volume of the part is V', (V-Vp)/(V'-Vp) x 100 (%) is 120% or more and 300% or less,
Electric fusion fittings. The V and the P satisfy 0.21≦V/P≦0.74,
The electrofusion joint according to claim 1.

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