JP2023174497A - Fusing method, fusing system and fusing equipment - Google Patents

Abstract

To provide a fusion method capable of suppressing overheating and stably developing fusion strength.SOLUTION: A fusion method for fusing an electric fusion joint 1 containing a thermoplastic resin, and having a cylindrical main body part 11 having joint socket parts 21 and 22 into which resin pipes 2 and 3 containing a thermoplastic resin are inserted and socket heating parts 13 and 14 including heating wires 31 and 32 disposed in the joint socket parts 21 and 22 to resin pipes 2 and 3, comprises steps S1, S5, and S6. The step S1 is configured to insert the resin pipes 2 and 3 inside the joint sockets 21 and 22 of the electric fusion joint 1. The step S5 is configured to energize the heating wires 31 and 32 of the socket heating parts 13 and 14 to heat the thermoplastic resin contained in the resin pipes 2 and 3 to a temperature of T1°C or higher and T2°C or lower. The step S6 is configured to maintain a temperature of the thermoplastic resin contained in the resin pipes 2 and 3 at T1°C or higher and T2°C or lower.SELECTED DRAWING: Figure 9

Description

The present disclosure relates to a fusing method, a fusing system, and a fusing apparatus.

BACKGROUND ART Electric fusion joints are often used to connect pipe bodies 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).

The electric fusion joint shown in Patent Document 1 includes a pipe socket at both ends and a stopper formed in an annular shape at the back of the pipe socket, and heating wires are provided in the pipe socket and the stopper. There is.

By applying voltage to the heating element to generate heat with the tube bodies inserted into the two tube sockets of the electric fusion joint, the resin of the tube socket and stopper around the heating element and the resin of the tube body are are fused together, and the tube bodies are connected to each other via the electric fusion joint.

Japanese Patent Application Publication No. 5-318596

However, in the past, a constant voltage was applied to the heating element, so the resin temperature continued to rise, and if it exceeded a certain time, it would become overheated, resulting in a shortened fusion time and the possibility that the fusion strength could not be secured. There is. In addition, when the resin is overheated, the resin decomposes into low molecular weight molecules, which may reduce the strength.

An object of the present disclosure is to provide a fusion method, a fusion system, and a fusion device that can suppress overheating and stably develop fusion strength.

In order to achieve the above object, the fusion method according to the first disclosure includes a cylindrical main body having a joint socket into which a tube containing a thermoplastic resin is inserted; A fusion bonding method for fusion bonding an electric fusion joint containing a thermoplastic resin and a pipe, comprising: a socket heating part having a heated heating wire; , is provided. In the insertion step, a tube is inserted inside the joint socket of the electric fusion joint. In the heating step, the heating wire of the socket heating section is energized to heat the thermoplastic resin contained in the tube to within a predetermined temperature range. The heat retention step maintains the temperature of the thermoplastic resin contained in the tube within a predetermined temperature range.

In this way, by maintaining the temperature of the thermoplastic resin contained in the tube within a predetermined temperature range, it is possible to maintain the temperature at which the resin melts and suppress overheating. Further, by maintaining the temperature of the thermoplastic resin contained in the tube within a predetermined temperature range, the fusion time can be extended, and it becomes possible to stably develop fusion strength.

The fusion method according to the second disclosure is the fusion method according to the first disclosure, in which the electric fusion joint further includes a stopper part and a stopper heat generating part. The stopper part is provided on the inner surface of the main body part so as to protrude inwardly, and regulates the insertion position of the end surface of the pipe when the pipe is inserted inside the joint socket part. The stopper heat generating part has a heating wire arranged in the stopper part. In the heating step, the heating wire of the stopper heating section is energized together with the heating wire of the socket heating section. In the insertion step, the tube is inserted into the electric fusion joint until the end surface of the tube hits the stopper part. The fusion method further includes a pressurizing step of applying force to the tube toward the stopper portion.

In this manner, even in the fusion connection of a pipe and an electric fusion joint provided with a stopper portion for regulating the position of the pipe, it is possible to maintain the temperature at which the resin melts and suppress overheating. Further, by maintaining the temperature of the thermoplastic resin contained in the tube within a predetermined temperature range, the fusion time can be extended, and it becomes possible to stably develop fusion strength.

In addition, by fusion-bonding the stopper part and the end face of the pipe, the connection can be made without creating any gaps, and such a piping structure of electric fusion joints and pipes can be used for ultrapure water. . When such a piping structure is used for ultrapure water, if the thermoplastic resin is overheated, there is a risk that a low-molecular composition in which the polymer is decomposed may be mixed into the water, but according to the present disclosure, Since overheating of the thermoplastic resin can be suppressed, it is possible to prevent impurities from being mixed into water.

The fusion method according to the third disclosure is the fusion method according to the first or second disclosure, in which the voltage applied to the heating wire in the heat retention step is 0.0% of the voltage applied to the heating wire in the heating step. A voltage of 6 times or more and 0.9 times or less is applied to the heating wire.

Thereby, it is possible to maintain the melting temperature of the thermoplastic resin, suppress overheating, and extend the fusion time, so that fusion strength can be stably developed.

The fusion method according to the fourth disclosure is the fusion method according to the first or second disclosure, in which the predetermined temperature range is equal to or higher than the melting point of the thermoplastic resin contained in the tube, below the thermal decomposition onset temperature.

Thereby, it is possible to suppress thermal decomposition due to overheating of the thermoplastic resin and to extend the fusion time, so that fusion strength can be stably developed.

The fusion method according to the fifth disclosure is the fusion method according to the first or second disclosure, in which the temperature of the thermoplastic resin is the temperature at the interface between the pipe and the electric fusion joint. The predetermined temperature range is 160 degrees or more and 250 degrees or less.

In this way, by setting the temperature at the interface between the pipe and the electric fusion joint to 160 degrees or more and 250 degrees or less, overheating can be suppressed and the fusion time can be extended, resulting in stable It is possible to develop fusion strength.

A fusion system according to a sixth disclosure includes a pipe, an electric fusion joint, and a fusion device. The tube includes thermoplastic resin. The electric fusion joint includes a thermoplastic resin, and has a cylindrical main body, a socket heat generating part, and a connector attachment part. The main body has a joint socket into which the tube is inserted. The socket heat generating part has a heating wire arranged in the joint socket part. The connector attachment part is arranged on the outer surface of the main body part and connected to the heating wire. The fusion device includes a connector and a control section. The connector is attached to the connector attachment part. The control section heats the thermoplastic resin contained in the tube to within a predetermined temperature range by energizing the heating wire of the socket heating section via the connector mounting section, and brings the temperature of the thermoplastic resin contained in the tube within the predetermined temperature range. control to maintain the

In this way, by maintaining the temperature of the thermoplastic resin contained in the tube within a predetermined temperature range, it is possible to maintain the temperature at which the resin melts and suppress overheating. Further, by maintaining the temperature of the thermoplastic resin contained in the tube within a predetermined temperature range, the fusion time can be extended, and it becomes possible to stably develop fusion strength.

A fusion device according to a seventh disclosure includes a cylindrical main body portion having a joint socket into which a tube containing a thermoplastic resin is inserted, and a socket having a heating wire disposed in the joint socket. A fusion device for welding an electric fusion joint containing a thermoplastic resin and a pipe, the fusion device having a heat generating part and a connector attachment part disposed on the surface of a main body part and connected to a heating wire, It includes a connector and a control section. The connector is attached to the connector attachment part. The control section heats the thermoplastic resin contained in the tube to within a predetermined temperature range by energizing the heating wire of the socket heating section via the connector mounting section, and brings the temperature of the thermoplastic resin contained in the tube within the predetermined temperature range. control to maintain the

In this way, by maintaining the temperature of the thermoplastic resin contained in the tube within a predetermined temperature range, it is possible to maintain the temperature at which the resin melts and suppress overheating. Further, by maintaining the temperature of the thermoplastic resin contained in the tube within a predetermined temperature range, the fusion time can be extended, and it becomes possible to stably develop fusion strength.

According to the present disclosure, it is possible to provide a fusion method, a fusion system, and a fusion device that can suppress overheating and stably develop fusion strength.

1 is a diagram showing a fusion system in Embodiment 1 according to the present disclosure. FIG. It is a figure showing a resin pipe, an electric fusion joint, and a resin pipe in Embodiment 1 concerning this indication. 1 is a diagram showing a cross-sectional configuration of an electric fusion joint in Embodiment 1 according to the present disclosure. 4 is a cross-sectional configuration diagram showing a state in which a resin pipe is inserted into the electric fusion joint of FIG. 3. FIG. FIG. 2 is a perspective view showing a jig in Embodiment 1 of the present disclosure. 6 is a schematic plan view showing the jig of FIG. 5. FIG. Diagram showing the resin pipe, electric fusion joint, and resin pipe attached to the jig (a) is a graph showing the relationship between applied voltage and time, and FIG. 8(b) is a graph showing the temperature of the thermoplastic resin when voltage is applied as shown in FIG. 8(a). FIG. 2 is a flow diagram showing a fusion method according to Embodiment 1 of the present disclosure. 8 is a cross-sectional configuration diagram showing a state in which the resin pipe, electric fusion joint, and resin pipe of FIG. 7 are fused together. FIG. FIG. 3 is a cross-sectional configuration diagram of an electric fusion joint according to a second embodiment of the present disclosure. 12 is a cross-sectional configuration diagram showing a state in which a resin pipe is inserted into the electric fusion joint of FIG. 11. FIG. It is a figure showing the relationship between time and resin temperature in a comparative example.

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

(Embodiment 1)
<Configuration>
FIG. 1 is a diagram showing the configuration of a fusion system 100 in an embodiment of the present disclosure. As shown in FIG. 1, the fusion system 100 includes an electric fusion joint 1, a resin pipe 2 (an example of a pipe), a resin pipe 3 (an example of a pipe), and a fusion device 4. The electric fusion joint 1, the resin pipe 2, and the resin pipe 3 are thermally fused by the fusion device 4.

FIG. 2 is a diagram showing an electric fusion joint 1, a resin pipe 2 connected by the electric fusion joint, and a resin pipe 3 in an embodiment of the present disclosure. FIG. 1 can also be said to be an exploded view of the piping structure 110. The piping structure 110 includes, for example, an electric fusion joint 1, a resin pipe 2, and a resin pipe 3.

As shown in FIG. 2, the electric fusion joint 1 is fused to a resin pipe 2 and a resin pipe 3 to connect the resin pipe 2 and the resin pipe 3. The resin pipe 2 and the resin pipe 3 are each made of thermoplastic resin. Examples of thermoplastic resins include polyolefins such as polyethylene.

The resin pipes 2 and 3 have flow passages 2f and 3f having circular cross sections extending therein. The electric fusion joint 1 has a flow path 1f having a circular cross section extending therein. When the resin pipe 2 and the resin pipe 3 are connected by the electric fusion joint 1, the axes of the flow paths of the resin pipe 2, the resin pipe 3, 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 2, and the resin pipe 3 extend is defined as the axial direction A. Further, in the electric fusion joint 1, the resin pipe 2, and the resin pipe 3, 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 2 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 3 is connected to the electric fusion joint 1 by moving relative to the electric fusion joint 1 in the direction of arrow A2 in the axial direction A. A state in which the resin pipe 2 and the resin pipe 3 are fused and connected to the electric fusion joint 1 constitutes a piping structure 110 .

(Electric fusion joint 1)
FIG. 3 is a diagram showing a cross-sectional configuration of the electric fusion joint 1. As shown in FIG. Electric fusion joint 1 contains thermoplastic resin. As shown in FIG. 3, the electric fusion joint 1 includes a main body portion 11, a stopper portion 12, socket heat generating portions 13 and 14, a stopper heat generating portion 15, and a connector mounting portion 16.

(Main body part 11)
The main body portion 11 is made of thermoplastic resin. The main body part 11 has a cylindrical shape and includes a joint socket part 21 , a joint socket part 22 , and a continuous part 23 . The thermoplastic resin used in the main body portion 11 is not particularly limited, but may include polyolefins such as polyethylene having a melting point of less than 230°C. As the thermoplastic resin, PE (polyethylene), which has a small amount of elution, may be used. As the thermoplastic resin, HDPE (high-density polyethylene resin) having a melting point of about 130° C. and having a small amount of elution may be used.

The joint socket part 21 is arranged on the one end 11b side of the main body part 11. The resin pipe 2 is inserted inside the joint socket 21 . The joint socket portion 22 is cylindrical. The joint socket part 22 is arranged on the other end 11c side of the main body part 11. The joint socket portion 22 is cylindrical. The resin pipe 3 is inserted inside the joint socket 22 .

The connecting portion 23 is continuous with the joint socket portion 21 and the joint socket portion 22 as shown in FIG. 2, and connects the joint socket portion 21 and the joint socket portion 22. The continuous portion 23 is a portion that connects the joint socket portion 21 and the joint socket portion 22, and the stopper portion 12 is provided on the inside in the radial direction B.

The joint socket portion 21 has a protruding portion 24 that protrudes inward in the radial direction B from the inner surface 11a. The protrusion 24 has an annular shape. The protrusion 24 is formed along the entire circumference in the circumferential direction C. The protruding portion 24 is arranged in line with the stopper portion 12 in the axial direction A. The protruding portion 24 protrudes less inward in the radial direction than the stopper portion 12 . The protruding portion 24 forms a stepped shape on the inner circumferential surface of the joint socket portion 21 . The protrusion 24 has a side surface 24a and a peripheral surface 24b. The side surface 24a is formed perpendicularly to the axial direction A toward the inner side in the radial direction B from the inner surface 11a of the main body portion 11. The peripheral surface 24b is a radially inner end surface of the protrusion 24. The circumferential surface 24b is formed from the radially inner end of the side surface 24a toward the stopper portion 12 (in the direction of the end 11c), and is connected to the stopper portion 12. The peripheral surface 25b is formed parallel to the axial direction A. Note that in this specification, vertical may include a design error and includes a range that is generally accepted as vertical. Moreover, in this specification, parallel may include a design error and includes a range that is recognized as parallel based on socially accepted principles.

The joint socket portion 22 has a protruding portion 25 that protrudes inward in the radial direction B from the inner surface 11a. The protrusion 25 has an annular shape. The protrusion 25 is formed along the entire circumference in the circumferential direction C. The protruding portion 25 is arranged in line with the stopper portion 12 in the axial direction A. The protruding portion 25 protrudes less inward in the radial direction than the stopper portion 12 . The protruding portion 25 forms a stepped shape on the inner circumferential surface of the joint socket portion 21 . The protrusion 25 has a side surface 25a and a peripheral surface 25b. The side surface 25a is formed perpendicularly to the axial direction A toward the inner side in the radial direction B from the inner surface 11a of the main body portion 11. The peripheral surface 25b is a radially inner end surface of the protrusion 25. The circumferential surface 25b is formed from the radially inner end of the side surface 25a toward the stopper portion 12 (the end 11b direction), and is connected to the stopper portion 12. The peripheral surface 25b is formed parallel to the axial direction A.

FIG. 4 is a cross-sectional configuration diagram showing a state in which the resin pipe 2 is inserted inside the joint socket part 21 of the electric fusion joint 1, and the resin pipe 3 is inserted inside the joint socket part 22. As shown in FIG. 4, the resin pipe 2 is inserted inside the protrusion 24 of the joint socket 21. As shown in FIG. The resin pipe 3 is inserted inside the protrusion 25 of the joint socket 22 .

(Stopper part 12)
The stopper portion 12 is formed in an annular shape. The stopper portion 12 is formed on the inner surface 11a of the main body portion 11 along the circumferential direction C in the form of a protrusion over the entire circumference. The stopper portion 12 contains thermoplastic resin. For the stopper portion 12, preferably the same thermoplastic resin as that used for the main body portion 11 is used. Therefore, as the thermoplastic resin forming the stopper part 12, similarly to the main body part 11, a polyolefin such as polyethylene having a melting point of less than 230° C. can be used. As the thermoplastic resin, PE (polyethylene), which has a small amount of elution, may be used. As the thermoplastic resin, HDPE (high-density polyethylene resin) having a melting point of about 130° C. and having a small amount of elution may be used.

As shown in FIG. 3, the stopper portion 12 is formed to protrude radially inward from the inner surface 11a of the main body portion 11. Further, the stopper portion 12 is arranged inside the continuous portion 23 of the main body portion 11 in the radial direction B. Note that the stopper portion 12 may be formed as one member with the main body portion 11, or may be formed as a separate member from the main body portion 11.

The stopper part 12 is arranged between the protruding part 24 and the protruding part 25, as shown in FIG. The stopper portion 12 has a first side surface 12a, a second side surface 12b, and a peripheral surface 12c. The peripheral surface 12c is a radially inner end surface of the stopper portion 12.

The first side surface 12a is formed toward the inner side in the radial direction B from the end of the peripheral surface 24b of the protrusion 24 on the opposite side to the side surface 24a. The first side surface 12a is formed perpendicular to the axial direction A.

The second side surface 12b is formed toward the inner side in the radial direction B from the end of the peripheral surface 25b of the protrusion 25 opposite to the side surface 25a. The second side surface 12b is formed perpendicular to the axial direction A.

The circumferential surface 12c connects the radially inner end of the first side surface 12a and the radially inner end of the second side surface 12b. The peripheral surface 12c is formed parallel to the inner surface 11a of the main body portion 11.

When the resin pipe 2 is inserted inside the joint socket part 21, as shown in FIG. 4, the end surface 2a of the resin pipe 2 comes into contact with the first side surface 12a of the stopper part 12, and the insertion position of the end surface 2a is restricted. be done. Note that the end surface 2a of the resin tube 2 contacts the first side surface 12a when the end surface 2a directly contacts the first side surface 12a, and when the end surface 2a contacts the first side surface 12a through the heating wire 33 (described later) of the stopper heat generating section 15. This includes the case of indirectly contacting the first side surface 12a.

When the resin pipe 3 is inserted inside the joint socket part 22, as shown in FIG. 4, the end surface 3a of the resin pipe 3 comes into contact with the second side surface 12b of the stopper part 12, and the insertion position of the end surface 3a is restricted. be done. Note that the end surface 3a contacts the second side surface 12b when the end surface 3a directly contacts the second side surface 12b, and when the end surface 3a contacts the second side surface 12b via the heating wire 33 (described later) of the stopper heat generating part 15. including indirect contact with

(Socket heating parts 13, 14)
The socket heat generating parts 13 and 14 are provided in the joint socket parts 21 and 22, as shown in FIG. The socket heat generating part 13 has a heating wire 31 embedded in the protruding part 24 of the joint socket 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 circumferential surface 24b. The heating wire 31 is arranged near the peripheral surface 24b. The heating wire 31 may be partially buried in the protrusion 24 so as to be exposed from the circumferential surface 24b or the side surface 24a to the flow path 1f side, or may be completely buried. The protruding portion 24 has a length in the axial direction A that allows the heating wire 31 to be wound two times around it.

The socket heat generating part 14 has a heating wire 32 embedded in the protruding part 25 of the joint socket part 22, as shown in FIG. The heating wire 32 is arranged so as to be wound two times in the circumferential direction along the circumferential surface 25b. The heating wire 32 is arranged near the peripheral surface 25b. Note that the heating wire 32 may be buried in the protrusion 25 so that a portion thereof is exposed to the flow path 1f side from the circumferential surface 25b or the side surface 25a, or may be completely buried. The protruding portion 25 has a length in the axial direction A such that the heating wire 32 is wound around two times.

The heating wire 31 includes, for example, a conducting wire 31a, an insulating film 31b, and a covering resin 31c. The heating wire 32 includes, for example, a conducting wire 32a, an insulating film 31b, and a covering resin 32c. For the conductive wires 31a and 32a, 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 insulating films 31b and 32b are provided to cover the conductive wires 31a and 32a. The insulating films 31b and 32b 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 32b can be formed of, for example, fluororesin or imide resin, but it is more preferable to form them of polyimide resin. Note that the heating wires 31 and 32 do not need to have the insulating coatings 31b and 32b. The coating resins 31c and 32c are provided so as to cover the peripheries of the insulating films 31b and 32b. The coating resins 31c and 32c are made of thermoplastic resin. The same resin as the thermoplastic resin used in the main body portion 11 may be used for the coating resins 31c and 32c. As the thermoplastic resin, mention may be made of polyolefins such as polyethylene, which have a melting point of less than 230°C. As the thermoplastic resin, PE (polyethylene), which has a small amount of elution, may be used. As the thermoplastic resin, HDPE (high-density polyethylene resin) having a melting point of about 130° C. and having a small amount of elution may be used.

The socket heat generating part 13 is provided symmetrically with respect to the socket heat generating part 14 and the stopper part 12 as a reference. In this embodiment, the heating wires 31 and 32 are wound so as to be in contact with each other in the axial direction A, but they may not be in contact and a gap may be provided between them.

As shown in FIG. 3, in the axial direction A, the socket heat generating part 13 is arranged adjacent to the stopper part 12. Further, in the axial direction A, the socket heat generating part 14 is arranged adjacent to the stopper part 12. For example, as shown in FIG. 3, the heating wire 31 is arranged so as to be in contact with a virtual plane M1 extending the first side surface 12a outward in the radial direction B. Further, for example, as shown in FIG. 3, the heating wire 32 is arranged so as to be in contact with a virtual plane M2 extending the second side surface 12b outward in the radial direction B.

In this way, the socket heat generating parts 13 and 14 are arranged next to the stopper part 12 in the axial direction A so as to be in contact with the virtual planes M1 and M2. A predetermined interval may be provided between them.

Moreover, in each of the socket heat generating parts 13 and 14, the heating wires 31 and 32 are wound around two times in contact with each other, but the number of times does not have to be limited to two times. Further, all or part of the parts may not be in contact with each other. Further, a plurality of portions may be provided with a predetermined number of adjacent portions.

Moreover, although the socket heat generating part 13 and the socket heat generating part 14 are provided symmetrically with the stopper part 12 in between, the present invention is not limited thereto. For example, the heating wire 31 may be wound two times around one joint socket part 21 with the stopper part 12 in between, and the heating wire 32 may be wound three times around the other joint socket part 22.

(Stopper heat generating part 15)
The stopper heat generating part 15 is provided in the stopper part 12. The stopper heat generating section 15 has a heating wire 33. The heating wire 33 is provided on the stopper portion 12 so as to be wound in the circumferential direction C along the axial direction A. In this embodiment, the heating wire 33 is wound around the stopper portion 12, for example, four times. In the stopper heat generating section 15 of this embodiment, the adjacent heating wires 33 are all in contact, but a gap may be provided.

The heating wire 33 is embedded in the stopper portion 12 so as to be in contact with the circumferential surface 12c of the stopper portion 12, but a portion thereof is exposed to the flow path 1f side from the first side surface 12a, the second side surface 12b, or the circumferential surface 12c. It may be buried in the stopper part 12 as shown in FIG. The stopper portion 12 has a length in the axial direction A such that the heating wire 33 is wound around four times.

For example, as shown in FIG. 3, the heating wire 33 includes a conducting wire 33a, an insulating film 33b, and a covering resin 33c. As the conducting wire 33a, 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 insulating film 33b is provided to cover the periphery of the conductive wire 33a. The insulating film 33b 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 33b can be formed of, for example, a fluororesin or an imide resin, but it is more preferably formed of a polyimide resin. Note that the heating wire 33 does not need to have the insulating film 33b. The coating resin 33c is provided to cover the periphery of the insulating film 33b. The covering resin 33c is made of thermoplastic resin. The same resin as the thermoplastic resin used in the main body portion 11 may be used as the coating resin 33c. As the thermoplastic resin, mention may be made of polyolefins such as polyethylene, which have a melting point of less than 230°C. As the thermoplastic resin, PE (polyethylene), which has a small amount of elution, may be used. As the thermoplastic resin, HDPE (high-density polyethylene resin) having a melting point of about 130° C. and having a small amount of elution may be used.

In the present embodiment, one heating wire 33 is wound four times in the stopper heating section 15 so as to be in contact with its neighbor, but the invention is not limited to this, and the number of turns is less than three or more than five. Good too. Further, the stopper heating portion 15 may be formed by winding not only one heating wire 33 but two or more heating wires 33 . The heating wire 33 may be wound so that all or part thereof does not come into contact with the adjacent wire.

(Connector mounting part 16)
As shown in FIG. 3, the connector mounting portion 16 has two pins 41b and 41c. The two pins 41b and 41c are provided so as to protrude radially outward from the outer surface 11d of the main body portion 11. As shown in FIG. 3, one of the two pins 41b and 41c is arranged near the end 11b of the main body 11, and the other pin 41c is arranged near the end 11c. Although not shown, the two pins 41b and 41c are connected to the heating wires 31 and 32 of the socket heating parts 13 and 14 and the heating wire 33 of the stopper heating part 15. The pin 41b, the heating wire 31, the heating wire 32, the heating wire 33, and the pin 41c are connected in this order. In this embodiment, the heating wire 31, the heating wire 32, and the heating wire 33 are one heating wire. This single heating wire extends from the pin 41b to the socket heat generating part 13, forms the socket heat generating part 13, the stopper heat generating part 15, and the socket heat generating part 14 in this order, and extends to the pin 41c. When the connectors of the fusion device 4 are attached to the pins 41b and 41c and energized, the heating wires 31, 32, and 33 generate heat.

(Jig 5)
When the resin pipe 2 and the resin pipe 3 are fusion-bonded using the electric fusion joint 1, a jig 5 that supports the electric fusion joint 1, the resin pipe 2, and the resin pipe 3 is used.

The jig 5 will be explained below. The resin pipe 2, the electric fusion joint 1, and the resin pipe 3 are arranged on the jig 5. FIG. 5 is a diagram showing the jig 5. FIG. 6 is a schematic plan view showing the jig 5. As shown in FIG. FIG. 7 is a diagram showing a state in which the resin pipe 2, the electric fusion joint 1, and the resin pipe 3 are attached to the jig 5.

The jig 5 includes a first clamp section 210, a second clamp section 220, a shaft section 230, a pressing section 240, and a pedestal 250.

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

(First clamp part 210)
The first clamp part 210 clamps and fixes the resin pipe 2. 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 2, the resin pipe 3, and the electric fusion joint 1 are arranged on the jig 5, 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 part 212 is a generally rectangular parallelepiped member having 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 tube 2 between the recess 212a and the recess 211a formed therein. When the resin tube 2 is sandwiched between them, the central axes of the recess 212a and the recess 211a generally coincide. Moreover, in the state where the resin tube 2 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 2 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 tube 2 is arranged 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 3. The second clamp part 220 fixes the resin tube 3 so that the center axis of the resin tube 3 coincides with the center axis of the resin tube 2.

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 250 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 tube 3 between the recess 222a and the recess 221a formed therein. When the resin tube 3 is sandwiched between them, the central axes of the recess 222a and the recess 221a generally coincide. Moreover, in the state where the resin tube 3 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 3 is arranged along the recess 221a of the lower clamp part 221 with the hinge part 223 as the center and the space between the lower clamp part 221 and the upper clamp part 222 is open. Thereafter, the upper clamp part 222 rotates around the hinge part 223, and the resin tube 3 is arranged 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 2 and the resin pipe 3 inserted into the electric fusion joint 1, the resin pipe 2 is held between the first clamp part 210 and the resin pipe 3 is held between the second clamp part 220, so that the resin is attached to the jig 5. A pipe 2, a resin pipe 3, and an electric fusion joint 1 can be arranged.

(Shaft portion 230)
The shaft portion 230 is supported by a pedestal 250. 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 2 fixed to the first clamp portion 210 and the resin tube 3 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. For example, as shown in FIG. 6, the pressing section 240 includes an electric cylinder 241 and a connecting section 242.

As shown in FIG. 6, the electric cylinder 241 is arranged on the side of the pedestal 250. The electric cylinder 241 includes a motor (not shown), a rod 243, and a cylinder 244. The rod 243 is arranged parallel to the axial direction A. The rod 243 is movable along a direction parallel to the axial direction A with respect to the cylinder 244 by driving the motor.

The connecting portion 242 connects the rod 243 and the lower clamp portion 211. The connecting portion 242 is a substantially plate-shaped member. The connecting portion 242 is arranged in a direction (width direction) perpendicular to the axial direction A in plan view. One end 242a of the connecting portion 242 in the width direction is fixed to the rod 243. The other end 242b of the connecting portion 242 in the width direction is penetrated by the shaft portion 230. The end portion 242b is fixed to the lower clamp portion 211.

When the rod 243 moves toward the cylinder 244, the first clamp section 210 including the lower clamp section 211 moves toward the second clamp section 220 along the shaft section 230 (A1 direction).

As shown in FIG. 7, by applying a load to the first clamp part 210 by the pressing part 240 with the resin pipe 2, the resin pipe 3, and the electric fusion joint 1 arranged in the jig 5, the resin pipe A load is applied so that the end surface 2a of the resin tube 2 and the end surface 3a of the resin tube 3 are pressed against the stopper portion 12.

(Fusing device 4)
Next, the fusion device 4 that applies electricity to the electric fusion joint 1 will be explained.

As shown in FIG. 1, the fusing device 4 includes a pair of connectors 51b and 51c and a main body portion 52. The pair of connectors 51b and 51c are attached to the pins 41b and 41c of the connector attachment portion 16 of the electric fusion joint 1. The main body section 52 includes an operation section 53, an input section 54, and a control section 55. The operation unit 53 is operated by an operator. The operation unit 53 includes, for example, a start button for starting energization. The input unit 54 inputs information regarding the electric fusion joint 1 . The input unit 54 is shown as, for example, a barcode reader that reads a barcode attached to the electric fusion joint 1, but it is not limited to this, and may be a touch panel on which an operator manually inputs information. good. A plurality of types of electric fusion joints 1 are available with different outer diameters, inner diameters, wall thicknesses, or materials. The fusion device 4 specifies the type of the electric fusion joint 1 by reading information regarding the electric fusion joint 1 via the input unit 54, and controls energization according to the type.

The control unit 55 controls the power supplied to the electric fusion joint 1 . Control unit 55 includes a processor and a storage device. The processor is, for example, a CPU (Central Processing Unit). Alternatively, the processor may be a processor different from the CPU. The processor executes processing for controlling energization according to a program. Storage devices include non-volatile memory such as ROM (Read Only Memory) and volatile memory such as RAM (Random Access Memory). The storage device may include an auxiliary storage device such as a hard disk or a solid state drive (SSD). A storage device is an example of a non-transitory computer-readable recording medium. The storage device stores programs and data for controlling energization. The storage device stores energization programs for each type of electrical fusion joint 1.

FIG. 8(a) is a graph showing the relationship between applied voltage and time. FIG. 8(b) is a diagram showing the temperature when voltage is applied as shown in FIG. 8(a). The temperature is the temperature at position P1 in FIG. Position P1 is the interface between electric fusion joint 1 and resin pipe 2. Specifically, the position P1 is provided on the end surface 2a of the resin pipe 2, is near the heating wire 33 when the resin pipe 2 is inserted into the electric fusion joint 1, and is located near the heating wire 33 when the resin pipe 2 is inserted into the electric fusion joint 1. This is the position in contact with the first side surface 12a of the stopper portion 12. The position P1 is a position between the stopper heat generating part 15 and the socket heat generating part 13 in the radial direction B when the resin pipe 2 is inserted into the electric fusion joint 1.

As shown in FIG. 8A, the control unit 55 applies the first predetermined voltage V1 to the electric fusion joint 1 from time t0 when energization is started to time t1. Next, the control unit 55 switches the applied voltage from V1 to V2 at time t1, and applies the second predetermined voltage V2 to the electric fusion joint 1 from time t1 to time t2. The second predetermined voltage V2 is set to a lower temperature than the first predetermined voltage V1.

By applying the first predetermined voltage V1, the temperature of the thermoplastic resin at the position P1 of the end surface 2a of the resin tube 2 increases. By applying the first predetermined voltage V1 for a predetermined time D1 (from time t0 to time t1), the temperature of the thermoplastic resin at position P1 falls within a temperature range suitable for fusion bonding. The temperature suitable for fusion bonding is shown in FIG. 8(b) as T1 or higher and T2 or lower. In other words, for each type of electric fusion joint 1, the first predetermined voltage V1 and the first predetermined voltage V1 are set so that the temperature of the thermoplastic resin at position P1 falls within the temperature range T1 to T2 suitable for fusion bonding. The predetermined time period D1 (time t0 to t1) to be applied is determined in advance through experiments and stored in the storage device. The temperature T1° C. can be set, for example, to the melting temperature of the thermoplastic resin. The temperature T2°C can be set, for example, to a temperature at which the thermoplastic resin becomes overheated if it exceeds T2°C. Further, the temperature T1°C can be set to the melting point of the thermoplastic resin, and the temperature T2°C can be set to the temperature at which thermal decomposition of the thermoplastic resin starts or the temperature at which carbonization of the thermoplastic resin starts when it becomes higher than T2°C. . For example, T1°C can be set to 160°C and T2°C to 250°C. The temperature range suitable for fusing the thermoplastic resin can be set to a range of 160°C or higher and 250°C or lower. The first predetermined voltage V1 is set to a value that provides enough power to prevent the thermoplastic resin from emitting smoke. For example, the first predetermined voltage V1 can be set to 20V or more and 80V or less. As described above, when the first predetermined voltage V1 is applied for a predetermined time D1, the temperature of the thermoplastic resin at the position P1 reaches a predetermined temperature T3 within the range of T1 or more and T2 or less.

By switching from the first predetermined voltage V1 to the second predetermined voltage V2 at time t1 and applying the second predetermined voltage V2 to the electric fusion joint 1, the temperature of the thermoplastic resin at the position P1 is adjusted to fusion. It is possible to keep the temperature within a suitable temperature range T1 to T2. In other words, for each type of electric fusion joint 1, the second predetermined voltage V2 and the predetermined time D2 for applying the second predetermined voltage V2 that can supply the amount of heat necessary for fusion are determined in advance through experiments. is stored in the storage device. In this way, since the first predetermined voltage V1, the predetermined time D1, the second predetermined voltage V2, and the predetermined time D2 are stored in the storage device, welding can be performed appropriately without, for example, providing a temperature sensor or the like. I can do it.

Note that since fusion starts when the resin temperature reaches T1 or more, the time t3 at which the resin temperature reaches T1 is earlier than time t1, and the fusion time D3 is from time t3 to time t2. The magnitude of the second predetermined voltage V2 can be set, for example, to a value of 0.6 times or more and 0.9 times or less of the first predetermined voltage V1, more preferably 0.70 times or more, It is 0.86 times or less.

<Fusing method>
Next, a fusion method according to an embodiment of the present disclosure will be described. Note that FIG. 9 is a flow diagram for explaining the fusion method of this embodiment.

First, in step S1, the resin pipe 2 is inserted inside the joint socket part 21 of the electrofusion joint 1 until the relative movement of the end surface 2a of the resin pipe 2 is regulated by the stopper part 12. Further, the resin pipe 3 is inserted inside the joint socket part 22 of the electric fusion joint 1 until the relative movement of the end surface 3a of the resin pipe 3 is restricted by the stopper part 12. FIG. 4 shows a state in which the resin pipe 2 and the resin pipe 3 are inserted into the electric fusion joint 1. In addition, when inserting into the electric fusion joint 1, the end surface 2a of the resin pipe 2 and the outer surface near the end surface 2a, and the end surface 3a of the resin pipe 3 and the outer surface near the end surface 3a may be scraped. Step S1 corresponds to an example of an insertion process.

Next, in step S2, as shown in FIG. 2. Electric fusion joint 1 and resin pipe 3 are arranged.

Next, in step S3, the connectors 51b and 51c of the fusion device 4 are attached to the two pins 41b and 41c of the connector attachment portion 16.

Next, in step S4, the operator uses the input unit 54, so that the control unit 55 acquires information regarding the electric fusion joint 1.

Next, in step S5, when the operator operates the operation unit 53, the control unit 55 applies the first predetermined voltage V1, which is preset according to the type of the electric fusion joint 1, for a predetermined time D1. The voltage is applied to the electric fusion joint 1. By applying the first predetermined voltage V1 for a predetermined time D1, the temperature of the thermoplastic resin at the position P1 on the end surface 2a of the resin tube 2 reaches a temperature range suitable for fusion bonding. Step S5 corresponds to an example of a heating process.

Next, in step S6, the control unit 55 switches the applied voltage from the first predetermined voltage V1 to the second predetermined voltage V2, and applies the second predetermined voltage V2 for a predetermined time D2. This provides the thermoplastic resin with the amount of heat necessary for fusion. Step S6 corresponds to an example of a heat retention process. Further, in both step S5 and step S6, by driving the electric cylinder 241 to move the rod 243 toward the A1 side, a load toward the second clamp section 220 is applied to the first clamp section 210. By applying the load of the first clamp section 210 toward the second clamp section 220, the end surface 2a of the resin tube 2 is pressed against the first side surface 12a of the stopper section 12, and the end surface 3a of the resin tube 3 is pressed against the second side surface 12a of the stopper section 12. It is pressed against the side surface 12b. By applying the amount of heat necessary for fusion to the electric fusion joint 1 and pressing the resin pipes 2 and 3 against the electric fusion joint 1, the fusion between the electric fusion joint 1 and the resin pipes 2 and 3 is achieved. It will be done. Step S5 and step S6 correspond to an example of a pressurizing process.

Next, in step S7, the melted resin pipe 2, electric fusion joint 1, and resin pipe 3 are cooled for a predetermined period of time. Note that the pressing may be continued until the cooling in step S7 is completed, or may be stopped at the same time as the heating is stopped in step S6.

FIG. 10 is a sectional view showing a state in which the resin pipe 2, the electric fusion joint 1, and the resin pipe 3 are fused together. The stopper portion 12, the end surface 2a of the resin tube 2, and the end surface 3a of the resin tube 3 are melted, pressed by the resin tubes 2 and 3, and narrowed, filling the gap between the resin tubes 2 and 3, and forming a bead R. . The bead R is formed by melting the thermoplastic resin of the coating resin 33c of the heating wire 33, the stopper portion 12, the end surface 2a of the resin tube 2, and the end surface 3a of the resin tube 3. By pressing the pressing part 240 in a state where the resin is molten, the resin pipes 2 and 3 move inside the electric fusion joint 1 while crushing the stopper part 12, and a bead R is formed according to the amount of movement. . Further, the outer surface 2d of the resin pipe 2 and the resin around the heating wire 31 of the socket heat generating part 13 are fused, and the outer surface 3d of the resin pipe 3 and the resin around the heating wire 32 of the socket heat generating part 14 are fused. do.

(Ultrapure water application of piping structure 110)
Unlike Embodiment 2, which will be described later, in the piping structure 110 of Embodiment 1, no gap is formed between resin pipe 2 and resin pipe 3, so that retention of liquid is suppressed. Therefore, the piping structure 110 of Embodiment 1 can be used, for example, to transport ultrapure water. Specifically, the piping structure 110 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 110 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, the piping structure 110 of the embodiment according to the present disclosure may have, for example, a polyethylene resin layer, and has excellent workability. For example, fusion bonding such as EF (electrofusion) bonding can be easily performed at relatively low temperatures.
Note that when the electric fusion joint 1 is used for ultrapure water, the bead R is the only part of the electric fusion joint 1 that comes into contact with ultrapure water. Therefore, as the coating resin 33c of the heating wire 33 forming the bead R and the thermoplastic resin forming the stopper part 12, it is preferable to use HDPE (high density polyethylene resin), which has a small amount of elution.

(Embodiment 2)
Next, an electric fusion joint 300 according to a second embodiment of the present disclosure will be described. FIG. 11 is a sectional view showing an electric fusion joint 300 of the second embodiment.

The electric fusion joint 300 of the second embodiment is different from the electric fusion joint 1 of the first embodiment in that the stopper portion 12 is not provided. Furthermore, the number of windings of the heating wires 31 and 32 in the socket heating section is different from that of the first embodiment.

The electric fusion joint 300 includes a main body portion 311 , socket heat generating portions 313 and 314 , and a connector attachment portion 16 . The main body part 311 has a cylindrical shape and includes a joint socket part 321 , a joint socket part 322 , and a continuous part 323 . The main body portion 311 includes thermoplastic resin. The thermoplastic resin used in the main body portion 311 is not particularly limited, but preferably has a melting point of less than 230°C. Examples of thermoplastic resins include polyolefins such as polyethylene.

The joint socket part 321 is arranged on one end 311b side of the main body part 311. The resin pipe 2 is inserted inside the joint socket 321 . The joint socket portion 322 is cylindrical. The joint socket part 322 is arranged on the other end 311c side of the main body part 311. The joint socket portion 322 is cylindrical. The resin pipe 3 is inserted inside the joint socket 322 . The connecting portion 323 is continuous with the joint socket portion 321 and the joint socket portion 322, as shown in FIG. 11, and connects the joint socket portion 321 and the joint socket portion 322. The continuous part 323 is a part that connects the joint socket part 321 and the joint socket part 322.

The joint socket portion 321 has a protrusion portion 324 that protrudes inward in the radial direction B from the inner surface 311a of the main body portion 311. The protrusion 324 has an annular shape. The protruding portion 324 is formed over the entire circumference in the circumferential direction C. The protruding portion 324 forms a stepped shape on the inner circumferential surface of the joint socket portion 21 . The protruding portion 324 has a first side surface 324a, a second side surface 324b, and a peripheral surface 324c. The first side surface 324a is formed perpendicularly to the axial direction A toward the inner side in the radial direction B from the inner surface 311a of the main body portion 311. The second side surface 324b is formed perpendicularly to the axial direction A toward the inner side in the radial direction B from the inner surface 311a of the main body portion 311. The first side surface 324a is arranged closer to the end 311b than the second side surface 324b. The circumferential surface 324c connects the inner end of the first side surface 324a in the radial direction B and the inner end of the second side surface 324b in the radial direction. The peripheral surface 324c is formed parallel to the axial direction A.

The joint socket portion 322 has a protruding portion 325 that protrudes inward in the radial direction B from the inner surface 311a of the main body portion 311. The protrusion 325 has an annular shape. The protruding portion 325 is formed over the entire circumference in the circumferential direction C. The protruding portion 325 forms a stepped shape on the inner circumferential surface of the joint socket portion 22 . The protruding portion 325 has a first side surface 325a, a second side surface 325b, and a peripheral surface 325c. The first side surface 325a is formed perpendicularly to the axial direction A toward the inner side in the radial direction B from the inner surface 311a of the main body portion 311. The second side surface 325b is formed perpendicularly to the axial direction A toward the inner side in the radial direction B from the inner surface 311a of the main body portion 311. The first side surface 325a is arranged closer to the end 311c than the second side surface 325b. The circumferential surface 325c connects the inner end in the radial direction B of the first side surface 325a and the inner end in the radial direction of the second side surface 325b. The peripheral surface 325c is formed parallel to the axial direction A.

The socket heat generating part 313 is arranged on the protruding part 324 of the joint socket part 321, as shown in FIG. The socket heating section 313 has a heating wire 31 embedded in a protrusion 324, as shown in FIG. The heating wire 31 is arranged so as to be wound eight times in the circumferential direction C along the circumferential surface 324c of the protrusion 324. The heating wire 31 is arranged near the peripheral surface 324c. In addition, the heating wire 31 may be buried in the joint socket part 321 so that a part is exposed to the flow path 300f side from the surrounding surface 324c, or may be completely buried. The protruding portion 324 has a length in which the heating wire 31 is wound eight times in the axial direction A.

The socket heat generating part 314 is arranged on the protruding part 325 of the joint socket part 322. The socket heat generating part 314 has a heating wire 32 embedded in a protrusion 325, as shown in FIG. The heating wire 32 is arranged so as to be wound eight times in the circumferential direction C along the circumferential surface 325c of the protrusion 325. The heating wire 32 is arranged near the peripheral surface 325c. In addition, the heating wire 32 may be buried in the joint socket part 321 so that a part is exposed to the flow path 300f side from the surrounding surface 325c, or may be completely buried. The protruding portion 325 has a length in which the heating wire 32 is wound eight times in the axial direction A. The heating wires 31 and 32 have the same configuration as in the first embodiment.

The socket heat generating part 313 and the socket heat generating part 314 are formed symmetrically with respect to the center of the main body part 311 in the axial direction A. The heating wire 31 of the socket heating section 313 and the heating wire 32 of the socket heating section 314 are connected. The pin 41b, the heating wire 31, the heating wire 32, and the pin 41c are connected in this order. In this embodiment, the heating wire 31 and the heating wire 32 are one heating wire. This single heating wire extends from the pin 41b to the socket heat generating part 313, forms the socket heat generating part 313 and the socket heat generating part 314 in this order, and extends to the pin 41c. When the connectors of the electric fusion device are attached to the pins 41b and 41c and energized, the heating wires 31 and 32 generate heat.

FIG. 12 is a diagram showing a state in which the resin pipe 2 and the resin pipe 3 are inserted into the electric fusion joint 300 of the second embodiment. The resin pipe 2 is inserted into the joint socket part 321 beyond the socket heat generating part 313 to the back side. The resin pipe 3 is inserted into the joint socket part 322 beyond the socket heat generating part 314 to the back side. It is fixed in this state, the connectors 51b and 51c of the fusion device 4 are attached to the pins 41b and 41c of the connector attachment part 16, and electricity is supplied. The power control method in the second embodiment is the same as that in the first embodiment.

In the second embodiment, the positions of the resin pipes 2 and 3 with respect to the electric fusion joint 300 may be fixed using the jig 5 of the first embodiment, but it is necessary to press the resin pipes 2 and 3 against the stopper part. Therefore, the jig 5 does not need to be provided with the pressing part 240. That is, in the second embodiment, it is not necessary to press the resin pipes 2 and 3 against the electric fusion joint 300 in step S5 and step S6. In the second embodiment, by applying electricity, the outer surface 2d of the resin pipe 2 and the resin around the heating wire 31 of the socket heat generating part 313 are fused, and the outer surface 3d of the resin pipe 3 and the resin around the socket heat generating part 314 are fused. The resin around the heating wire 32 is fused. In this embodiment, the first predetermined voltage V1, the predetermined time D1, the second predetermined voltage V2, and the predetermined time D2 are set so that the resin temperature at the position P2 is kept within the range of T1° C. or higher and T2° C. or lower. has been done. Position P2 is the interface between the electric fusion joint 200 and the resin pipe 2. Position P2 is shown in FIG. 12 and is provided on the outer surface 2d of the resin pipe 2, near the heating wire 31 and around the protrusion 324 when the resin pipe 2 is inserted into the electric fusion joint 300. This is the position where it contacts the surface 324c.

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

(A)
In the first and second embodiments described above, as shown in FIG. 8(b), the temperature of the heat-transferable resin is constant from time t1 to time t2, but the amount of heat necessary for fusion is supplied. If possible, it may be increased or decreased within the range of temperature T1 or higher and T2 or lower.

(B)
In the first and second embodiments described above, the voltage value is switched once from the first predetermined voltage V1 to the second predetermined voltage V2, but it may be switched multiple times. The first predetermined voltage V1 may be gradually increased to the second predetermined voltage V2. For example, when the first predetermined voltage V1 is applied and the temperature reaches T1 at time t3, the third predetermined voltage, which is a value between the first predetermined voltage V1 and the second predetermined voltage V2, is applied, and then the third predetermined voltage is applied. It is also possible to switch to the second predetermined voltage V2.

(C)
In the first and second embodiments described above, the voltage is changed, but the voltage is not limited to this, and in short, it is sufficient that the electric power supplied to the electric fusion joints 1 and 300 can be changed.

(D)
In the above embodiment, when viewed along the axial direction A, the outer diameter of the stopper portion 12 is circular, but it is not limited to a circle and may be polygonal.

(E)
In the embodiment described above, the socket heat generating part 13, the socket heat generating part 14, and the stopper part 12 are provided symmetrically, but the present invention is not limited to this.

(F)
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.

(G)
In the first embodiment described above, since the same heating wires 31, 32, and 33 of the socket heating parts 13, 14 and the stopper heating part 15 are used, all the heating wires 31, 32, and 33 are provided with an insulating film. However, it does not have to be limited to this. However, it is preferable that at least the heating wire 33 is provided with an insulating film. This is because the heating wires 33 are likely to come into contact with each other due to the pressure applied by the resin pipes 2 and 3. The heating wires 31 and 32 in the second embodiment also do not need to be provided with an insulating film.

(Example)
Next, the fusion method of this embodiment will be described in detail using examples.

(Examples 1 to 9, Comparative Examples 1 to 4)
In Examples 1 to 9 and Comparative Examples 1 to 4, the electric fusion joint 1 and resin pipes 2 and 3 described in Embodiment 1 were fused. The resin pipes 2 and 3 and the electric fusion joint 1 were made of HDPE (High-density polyethylene). In Examples 1 to 9 and Comparative Examples 1 to 4, the outer diameter and inner diameter of the resin tubes 2 and 3 were changed as shown in (Table 1) below, and the outer diameter and inner diameter of the resin tubes 2 and 3 were changed. An electric fusion joint 1 of the same type was used. Further, as shown in (Table 1), in Examples 1 to 9, fusion was performed by changing the first predetermined voltage V1, the second predetermined voltage V2, and the fusion time, and Comparative Examples 1 to 4 In this case, only the first predetermined voltage V1 was applied, but the second predetermined voltage V2 was not applied. Note that in Examples 1 to 9, the first predetermined voltage V1 and second predetermined voltage V2 are applied to the electric fusion joint 1, and in Comparative Examples 1 to 4, the first predetermined voltage V1 is applied to the electric fusion joint 1. When the voltage was being applied to the joint 1, the resin pipes 2 and 3 were pressed against the electric fusion joint 1.

The tensile strengths of the electric fusion joints 1, resin pipes 2, and resin pipes 3 that were fused under the respective conditions of Examples 1 to 0 and Comparative Examples 1 to 4 were measured and are shown in Table 1 below. The target value of the tensile strength was 20 MPa, and examples with a tensile strength of 20 MPa or more were marked as good and marked with a circle, and cases with a tensile strength of less than 20 MPa were marked as poor with a mark of x.

A first voltage was applied to the electric fusion joint 1, and when the temperature at position P1 reached 200° C., the voltage was switched to the second voltage.

Note that the fusion time is the time after the temperature at the position P1 reaches 200°C. The amount of heat during fusion was then calculated using equation (1).

比較例１～４では、図１３に示すように、時間の経過とともに樹脂温度が上昇するため、樹脂温度がＴ１以上Ｔ２以下の範囲内である融着時間Ｄ３が短くなる。一方、実施例１～９では、位置Ｐ１における樹脂温度を融着に適切な温度範囲に保持するため、融着時間を長くすることができ、十分な熱量を与えることができる。そのため、引張強度を確保した安定的な融着を行うことができた。 Amount of heat during fusion (kJ) = 2nd voltage x 2nd voltage/resistance value x fusion time...Equation (1)
Note that FIG. 13 is a diagram showing the relationship between time and resin temperature at position P1 in a comparative example. As shown in FIG. 13, when the first predetermined voltage V1 is applied, the resin temperature increases over time. In Comparative Examples 1 to 4, the application of the first voltage was stopped when the temperature reached 250° C. (T2) in order to prevent overheating.
(Table 1)

In Comparative Examples 1 to 4, as shown in FIG. 13, the resin temperature increases with the passage of time, so the fusion time D3 during which the resin temperature is within the range of T1 or higher and T2 or lower becomes shorter. On the other hand, in Examples 1 to 9, since the resin temperature at position P1 is maintained within a temperature range suitable for fusion, the fusion time can be increased and a sufficient amount of heat can be applied. Therefore, stable fusion bonding with sufficient tensile strength could be achieved.

(Examples 10-12, Comparative Examples 5-7)
In Examples 10 to 12 and Comparative Examples 5 to 7, the electric fusion joint 300 and resin pipes 2 and 3 described in Embodiment 2 were used. The resin pipes 2 and 3 and the electric fusion joint 300 are made of HDPE (High-density polyethylene). The first predetermined voltage is applied to the electric fusion joint 300 in the same manner as above, except that no pressure is applied during energization, and when the temperature at position P2 reaches 200° C., the second predetermined voltage is switched to perform fusion. was conducted to confirm the tensile strength.

比較例５～７に示すように、電気融着継手３００と樹脂管２、３の融着では、第１の所定電圧Ｖ１の印加だけでも引張強度は目標に達したが、第２の所定電圧Ｖ２を印加して融着時間を長くすることによって、融着時熱量を大きくすることができるため、引張強度をより大きくすることが可能となる。
上記実施例１～１２より、第２の所定電圧Ｖ２の大きさは、例えば、第１の所定電圧Ｖ１の０．７０倍以上、０．８６倍以下である方がより好ましいことがわかる。 The results are shown in Table 2 below.
(Table 2)

As shown in Comparative Examples 5 to 7, in the fusion of the electric fusion joint 300 and the resin pipes 2 and 3, the tensile strength reached the target even with only the application of the first predetermined voltage V1, but when the second predetermined voltage By applying V2 to lengthen the fusion time, the amount of heat during fusion can be increased, so it is possible to further increase the tensile strength.
From the above-mentioned Examples 1 to 12, it can be seen that the magnitude of the second predetermined voltage V2 is more preferably, for example, 0.70 times or more and 0.86 times or less of the first predetermined voltage V1.

1 : Electric fusion joint 2 : Resin pipe 3 : Resin pipe 13 : Socket heat generating part 14 : Socket heat generating part 21 : Joint socket part 22 : Joint socket part

Claims (7)

a cylindrical main body having a joint socket into which a tube containing a thermoplastic resin is inserted;
an electric fusion joint containing a thermoplastic resin, comprising: a socket heating section having a heating wire disposed in the joint socket;
A fusion method for fusion-bonding the pipe with the tube,
an insertion step of inserting the tube inside the joint socket of the electric fusion joint;
a heating step of heating the thermoplastic resin contained in the tube to within a predetermined temperature range by energizing a heating wire of the socket heating part;
A fusion method, comprising: a heat retention step of maintaining the temperature of a thermoplastic resin contained in the tube within the predetermined temperature range. The electric fusion joint is provided on the inner surface of the main body so as to protrude inward, and includes a stopper that restricts the insertion position of the pipe end of the pipe when the pipe is inserted inside the joint socket. and a stopper heating section having a heating wire disposed in the stopper section,
In the heating step, the heating wire of the stopper heating section is energized together with the heating wire of the socket heating section,
In the insertion step, the tube is inserted into the electric fusion joint until the end surface of the tube hits the stopper part,
further comprising a pressurizing step of applying force to the tube toward the stopper portion,
The fusion method according to claim 1. The voltage applied to the heating wire in the heat retention step is 0.6 times or more and 0.9 times or less of the voltage applied to the heating wire in the heating step.
The fusion method according to claim 1 or 2. The predetermined temperature range is equal to or higher than the melting point of the thermoplastic resin contained in the tube and lower than the thermal decomposition start temperature of the thermoplastic resin contained in the tube.
The fusion method according to claim 1 or 2. The temperature of the thermoplastic resin is the temperature at the interface between the pipe and the electrofusion joint,
The predetermined temperature range is 160 degrees or more and 250 degrees or less,
The fusion method according to claim 1 or 2. a tube containing a thermoplastic resin;
a cylindrical main body having a joint socket into which the pipe is inserted; a socket heating part having a heating wire disposed in the joint socket; an electric fusion joint comprising a thermoplastic resin and having a connector mounting portion connected to a heating wire;
The connector attached to the connector attachment part and the heating wire of the socket heat generating part are heated through the connector attachment part to heat the thermoplastic resin contained in the tube to within a predetermined temperature range. a control unit that controls the temperature of the thermoplastic resin to be maintained within the predetermined temperature range;
Fusion system with. a cylindrical main body having a joint socket into which a tube containing a thermoplastic resin is inserted; a socket heating part having a heating wire disposed in the joint socket; A fusion device for fusion bonding an electric fusion joint containing a thermoplastic resin, the connector attachment portion being arranged and connected to the heating wire, and the pipe,
a connector attached to the connector attachment part;
Electricity is applied to the heating wire of the socket heat generating part through the connector attachment part to heat the thermoplastic resin contained in the tube to within a predetermined temperature range, and the temperature of the thermoplastic resin contained in the tube is set to the predetermined temperature. A fusion device, which is equipped with a control unit that performs control to maintain within the range.

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