JP2023070442A - Electro fusion joint - Google Patents

Abstract

To avoid troubles occurring during construction or difficulty in transportation in an electro fusion joint.SOLUTION: An electro fusion joint 250 includes a fusion part in which a heating wire 300 is inserted into a cut groove spirally formed on an inner peripheral surface of a thermoplastic resin pipe into which a resin pipe to be connected thereto is inserted. The fusion part is provided on at least one of axial ends (both ends in this example) of the electro fusion joint 250 so as to be able to energize the heating wire 300 (via a terminal pin). At the fusion part, an outward path in which the spiral proceeds in an outward direction from the opening side of the electro fusion joint 250 to the opening side opposite to the opening and a return path provided in a reverse direction are formed by one heating wire 300. The electro fusion joint 250 includes recessed parts 252, in each of which the inner peripheral surface is recessed, on the inner peripheral surface at the opening side relative to the fusion part.SELECTED DRAWING: Figure 14

Description

TECHNICAL FIELD The present invention relates to an electric fusion joint used for connecting plastic pipes, and more particularly to an electric fusion joint having a structure in which a heating wire is inserted into a groove formed in the inner circumference of a thermoplastic resin pipe.

Electrofusion joints are usually manufactured using an injection molding method, and a heating wire is embedded in the inner peripheral portion of a joint body made of a thermoplastic resin such as polyethylene or polybutene. Such an electrofusion joint is sometimes called an EF (ElectroFusion) joint, an EF socket, or the like.
As such an electric fusion joint, a spiral groove is formed by cutting along the inner surface of a tube material made of a thermoplastic resin, centering on a large-diameter electric fusion joint, and a heating wire is inserted into the groove. A fitting is provided with a structure in which a Although the manufacturing method of the electric fusion joint having this structure is simple, it has been pointed out as a problem that it is difficult to manufacture the heating wire so that it does not rise from the groove. In view of such problems, Japanese Patent No. 5035672 (Patent Document 1) discloses an electric fusion joint having a structure in which a heating wire is inserted into a groove formed in the inner peripheral portion of a thermoplastic resin pipe. Disclosed is an electric fusion joint in which a heating wire does not rise from a groove due to temperature changes in the environment and voids do not occur at the fusion interface with a plastic pipe.

The electric fusion joint disclosed in Patent Document 1 is formed of a thermoplastic resin pipe into which a plastic pipe is inserted, and a helical portion with a small helical pitch and a portion with a large helical pitch on the inner peripheral surface of the resin pipe. a U-shaped groove, tongue-shaped portions formed on both sides of the opening of the groove, and a heating wire inserted into the groove, the width of the groove being equal to the diameter of the heating wire The depth of the groove is the same as or slightly narrower than the diameter of the heating wire, and the groove with a smaller helical pitch is shallower than the groove with a larger helical pitch. The heating wire inserted into the recessed groove portion with a small spiral pitch is embedded in the recessed groove with resin containing the molten tongue-shaped portion, and the heating wire inserted into the recessed groove portion with a large spiral pitch is pressed into the groove with a pressed tongue.

Japanese Patent No. 5035672

However, in the electric fusion joint disclosed in Patent Document 1, as described in paragraphs 0016 to 0018 of Patent Document 1, a thermoplastic resin sleeve is prepared and its inner peripheral surface is U-shaped. After forming the recessed groove in a spiral by cutting, the pressing tool is moved along the recessed groove while being pressed to deform the side wall to form a burr-like tongue-shaped portion protruding from the inner peripheral surface. After that, the heating wire is inserted over the entire length of the recessed groove.

Further, the electric fusion joint disclosed in Patent Document 1 is merely a joint for connecting two plastic pipes in series, as described in paragraph 0009 of Patent Document 1. More specifically, the inner peripheral surface of the sleeve consists of a left fused portion that melts and fuses the surface of the plastic tube inserted from the left and a fused portion that melts and fuses the surface of the plastic tube that is inserted from the right. the right fused portion, the left winding end portion between the left fused portion and the left connector pin (terminal pin), and the right wound end portion between the right fused portion and the right connector pin (terminal pin) , and a connecting portion between the left fused portion and the right fused portion, and the recessed groove is continuously formed from the left winding end to the right winding end. A heating wire is installed. That is, since it is assumed that the plastic pipes are fused to the left and right sockets of the electric fusion joint at the same time, one continuous heating wire runs from left to right (or from right to left) on the inner surface of the joint. It is wrapped in the direction

In such a structure, (1) even if the plastic pipes are fused and connected to both the left and right sockets, they must be fused at the same time and cannot be fused one by one. It is not possible to connect a plastic pipe to either the left or right socket by fusion bonding, and connect a plastic pipe, etc. to the other socket using a different connection method (one-sided electrical fusion There is a problem that the joint cannot be realized). Furthermore, the above problems (1) and (2) can be solved by arranging the left and right heating wires independently without providing a connecting portion. One of the terminal pins to be connected is arranged on the center side in the axial direction of the electric fusion joint. In this case, since the terminal pin is installed in the through hole penetrating the sleeve of the electric fusion joint, if the terminal pin is installed on the central side of the electric fusion joint, water leakage due to this through hole will occur. There is a problem that it may lead to Therefore, a total of four terminal pins must be arranged, two each on the left and right so as not to affect the watertightness.

However, the electric fusion joint disclosed in Patent Document 1 is merely a joint for connecting two plastic pipes to be connected in series and at the same time. There is neither a description nor a suggestion regarding disposing a total of four terminal pins, two each on the left and right, by making the left and right heating wires independent without providing a connecting portion.
In particular, when the terminal pin arranged in this way is connected to an external power supply to supply power to the heating wire, and the resin pipe (resin pipe) of the connection partner and the electric fusion joint are electrofused, the resin If the clearance between the pipe and the electrofusion joint is small, or if the electrical energy applied (supplied) by the electrofusion is large, the resin will be excessively melted, causing troubles during construction. Such an electric fusion joint has a problem that it is difficult to carry because there is no handle when handling (during production and construction). There is no mention or suggestion of

The present invention was developed in view of the above-mentioned problems, and its object is to provide a structure in which a heating wire is inserted into a groove formed in the inner peripheral part of a thermoplastic resin pipe, and a connection is provided. Instead of connecting the mating plastic pipe to both the left and right sockets at the same time, insert the left and right sockets one by one (Even if both the left and right are electrofused, only one of the left and right is electrofused and the other is not electrofused). To provide an electric fusion joint that can be electrically fused, avoiding troubles during construction or difficulty in transportation.

In order to achieve the above object, the electrofusion joint according to the present invention takes the following technical means.
That is, the electric fusion joint according to the present invention is a fusion part in which a heating wire is inserted into a notch groove formed in a spiral shape on the inner peripheral surface of a thermoplastic resin pipe into which a resin pipe to be connected is inserted. wherein the fusion part is provided on at least one end side in the axial direction of the electric fusion joint so as to be able to conduct electricity to the heating wire, and in the fusion part, An outward path in which the spiral progresses in the outward direction from the opening side of the electric fusion joint to the opening side on the opposite side of the opening and a return path in the direction opposite to the outward direction are formed by one heating wire, The inner peripheral surface on the opening side of the fused portion is provided with a recess formed by recessing the inner peripheral surface.

Preferably, the recess can be configured so as to extend along the inner circumference.
More preferably, the recess can be configured to serve also as a handle of the electric fusion joint.

According to the present invention, a structure is provided in which a heating wire is inserted into a concave groove formed in the inner circumference of a thermoplastic resin pipe, and the plastic pipe to be connected is connected to both the left and right sockets at the same time, but only one of the left and right sockets. It is an electrofusion joint that can be electrofused separately (even if both the left and right sides are electrofused, it does not matter if only one of the left and right sides is electrofused and the other is not electrofused). It is possible to provide an electrofusion joint that can be electrofused while avoiding the difficulty of carrying.

(A) Side view and (B) front view of the electrofusion joint according to the embodiment of the present invention, (C) arrow 1C cross-sectional view, (D) arrow 1D cross-sectional view, (E) arrow 1E cross-sectional view, (F) is a cross-sectional view of arrow 1F. FIG. 2 is a perspective view (part 1: outward path) for explaining the method of manufacturing the electrofusion joint shown in FIG. 1 ; 2 is a perspective view (part 2: return path) for explaining the method of manufacturing the electrofusion joint shown in FIG. 1; FIG. (A) Front view for explaining the relationship between the cutting tool and the electrofusion joint (here, the sleeve before processing) used in the method of manufacturing the electrofusion joint shown in FIGS. , (B) Front view (No. 2: return trip). 4(A) to (E) are plan views and (F) to (I) are perspective views of a special cutting tool used in the method of manufacturing the electrofusion joint shown in FIGS. 2 and 3. FIG. 6(A) to (C) are perspective views and (D) are front views for explaining the dimensions of each part of the dedicated cutter shown in FIG. 5. FIG. 3A and 3B are diagrams for explaining (A) an outward winding and (B) a return winding of the electrofusion joint 100. FIG. 3A and 3B are diagrams for explaining (A) an outward winding and (B) a return winding of the electrofusion joint 200; FIG. FIG. 4 is a diagram for explaining (A) an outward winding and (B) a return winding of an electrofusion joint according to a comparative example; 3A to 3B are plan views, (C) construction procedure diagrams, and (D) to (E) connection member diagrams for explaining terminal pins provided in the electric fusion joint. FIG. 3A to 3B are plan views, (C) a construction procedure diagram, and (D) a connection procedure diagram for explaining the terminal pin and the connection pin provided in the electric fusion joint according to the first modification; FIG. 10A to 10B are plan views, (C) a construction procedure diagram, and (D) a connection procedure diagram for explaining the terminal pin and the connecting cylinder provided in the electric fusion joint according to the second modification. . 13A and 13B are diagrams for explaining (A) an outward winding and (B) a return winding of an electric fusion joint 250 according to a third modification; FIG. 14 is a diagram for explaining the shape of the inner peripheral surface of the electric fusion joint 250 shown in FIG. 13; FIG.

An electrofusion joint and a method for manufacturing an electrofusion joint according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 10. FIG. In these FIGS. 1 to 10, the same components are denoted by the same reference numerals and have the same functions, and thus the description may not be repeated.
Here, the electrofusion joint according to the embodiment of the present invention is mainly an electrofusion joint having a medium or large diameter (for example, an inner diameter of 300 mm or more), and the electrofusion joint is a resin pipe made of a thermoplastic resin. (It may be described as a tube or sleeve) along the inner surface (may be described as the inner peripheral surface) spirally along the groove (the press cutting blade of the special blade described later The cross-sectional shape of this groove is V-shaped, for example, because it is V-shaped. Furthermore, the electric fusion joint according to the embodiment of the present invention may be of a double receiving type in which the heating wires are provided independently on the left and right sides, or may be of a single receiving type in which the heating wires are provided only on one of the left and right sides. Although it does not matter, the description below assumes that it is a double receiving type. In other words, the electric fusion joint according to the present embodiment does not provide a bridge portion on the central portion side in the axial direction as in Patent Document 1, and the left and right heating wires are made independent and electric fusion joints are provided at two locations on the left and right. A total of four terminal pins are arranged, two on each end side of the attachment joint, and a through hole for providing the terminal pin on the center side (a hole for penetrating the outer peripheral surface and the inner peripheral surface of the sleeve ), it has the feature of not affecting watertightness.

FIG. 1 shows an electric fusion joint 100 and an electric fusion joint 200 as the electric fusion joints according to the present embodiment. Two types of electrofusion joints having different wire end positions E and different winding pitches (manufactured by winding methods), which have the winding structure shown in FIG. is the electrofusion joint 100 shown in FIG. 1, and the electrofusion joint having the winding structure shown in FIG. 8 is the electrofusion joint 200 shown in FIG. The electric fusion joint having the winding structure shown in FIG. 9 is a comparative example.

Furthermore, as an example, adopting the winding structure shown in any one of FIGS. 7 and 8, using the special blade shown in FIGS. A helical groove formed along the inner peripheral surface of the tube material (sleeve) from the end side of the sleeve to the center side and the return path from the center side to the end side is press-cut with a dedicated blade. After the heating wire is inserted (embedded) in the groove at the same time as it is provided by cutting with a blade, the terminal pin shown in FIG. 10 and the inserted heating wire are securely connected, is completed.

<Overall Structure of Electrofusion Joint>
First, the overall structure of the electrofusion joint manufactured as described above will be described. As shown in FIGS. 1A and 1B, an electric fusion joint 100 (having a winding structure shown in FIG. 7) and an electric fusion joint 200 (having a winding structure shown in FIG. 8) according to the present embodiment As an example, in the case of a nominal diameter 250 (an electrofusion joint corresponding to a connection partner resin pipe having an outer diameter of 315 mm), the inner diameter is 317 mm, the outer diameter is 400 mm, and the axial length is 300 mm. , with a hollow cylindrical shape. In the following, when describing the absolute values of the electric fusion joint 100 including the special blade 1000, even if it is not noted, it is the numerical value for this electric fusion joint with a nominal diameter of 250 (inner diameter 315 mm). . In the following description, the electric fusion joint 100 and the electric fusion joint 200 may be described by using the electric fusion joint 100 as a representative. A heating wire 300 is helically embedded in the inner peripheral surface.

That is, in this electric fusion joint 100, the heating wire 300 is inserted into a notch groove formed spirally in the inner peripheral surface of a thermoplastic resin pipe (tube member, sleeve) into which the resin pipe to be connected is inserted. It has a fused part. This fusion portion is provided on at least one (here, both) end portion side of the electric fusion joint 100 in the axial direction so that the heating wire 300 can be energized (via the terminal pin 2000). In this fusion part, one heating wire has an outward path in which the spiral progresses in the outward direction from the opening side of the electric fusion joint 100 to the opening side on the opposite side of the opening, and a return path in the direction opposite to the outward direction. 300.

More specifically, as shown in FIGS. 1(C) to 1(F), the electric fusion joint 100 has a terminal pin on the start position S side (forward path start side) of one heating wire 300 on each of the left and right sides. 2000 (S side), and a terminal pin 2000 (E side) on the end position E side (backward end side). The terminal pin 2000 is a metal processed product, and has a structure to be reliably connected to the heating wire 300, although its detailed structure will be described later. In addition, the terminal pin 2000 in the electric fusion joint 100 is located at the same position in the circumferential direction on the start position S side and the end position E side, but is shifted in the axial direction. The terminal pin 2000 in 200 is arranged at substantially the same position in the axial direction on the start position S side and the end position E side, but at positions shifted in the circumferential direction. In any of the electric fusion joints, in order not to affect the watertightness (because the electric fusion joint according to the present embodiment is a double-ended type), there are two terminal pins on the left and right, and a total of four terminal pins. are located on the end side (rather than the axial center side) of the electrofusion joint. In order to arrange the terminal pin 2000 at such a position, the winding structure comprises a forward winding, a turn portion T and a return winding, as shown in FIGS.

The electric fusion joint 100 includes indicators 3000 embedded with injection-molded products corresponding to the positions of the left and right heating wires 300 . When electric power is supplied to the heating wire 300 via the terminal pin 2000, the indicator 3000 rises to confirm that electric fusion is being performed.

<Method for manufacturing electric fusion joint>
The electric fusion joint 100 according to the present embodiment, which has the above-described winding structure, is manufactured by manufacturing the electric fusion joint described below with reference to FIGS. It is embedded in the inner peripheral surface of the electric fusion joint so as to have an outward winding, a turn portion, and a return winding. 5 and 6 show a special blade 1000 used in the method for manufacturing an electrofusion joint described below.

The manufacturing method of the electrofusion joint 100 according to the present embodiment is to use a lathe to manufacture the electrofusion joint (in this case, the hollow cylindrical tubular material (sleeve) is used instead of the electrofusion joint as a finished product. A joint setting step for setting the joint so that it rotates, a blade setting step for setting a special blade (special blade 1000 shown in FIGS. 2 to 6) on the lathe, and a special blade 1000 by electrofusion. a fused portion forming step of forming a fused portion by moving the electrical fusion joint in the axial direction while contacting the inner peripheral surface of the electrical fusion joint and rotating the electrical fusion joint. Then, this fused portion forming step includes a groove cutting step of cutting a notch groove in the inner peripheral surface with a press cutting blade 1200 provided in the dedicated blade 1000, and a heating wire supply hole 1210 provided in the dedicated blade 1000 to feed the heating wire 300. is inserted into the notch groove (more specifically, the heating wire 300 inserted from the heating wire introduction hole 1110 provided in the body portion 1100 of the dedicated blade 1000 is discharged from the heating wire supply hole 1210 provided in the press cutting blade 1200 of the dedicated blade 1000. The heating wire inserting step of inserting the heating wire 300 into the notch groove by pressing the heating wire 300 by pressing the notch groove into which the heating wire 300 is inserted together with the heating wire 300 by the pressing guide 1300 provided in the dedicated blade 1000. and a heating wire fixing step for fixing in the cutout groove. Here, in the cutting tool setting step, the direction of the dedicated cutting tool 1000 is reversed 180 degrees in the inner peripheral direction, and the switching step of switching from the outward path to the return path (forming a turn portion T, which will be described later) can be executed. A cutting tool 1000 is set on the lathe. Note that the heating wire supply portion is the heating wire introduction hole 1110, the heating wire supply hole 1210, and a communication hole provided inside the dedicated blade 1000 connecting these holes with the same diameter (d1 described later). In some cases, these same diameters d<b>1 are described as representing the diameter of the heating wire supply hole 1210 .

Here, in the joint setting step described above, the lathe on which the electrofusion joint is set is preferably a general-purpose lathe or an NC (Numerical Control) lathe.
In addition, as shown in the relationship between the dedicated blade 1000 and the electric fusion joint in the outward trip shown in FIG. The dedicated blade 1000 has a structure in which the press cutting blade 1200, the heating wire supply hole 1210, and the holding guide 1300 are arranged in order to face the inner peripheral surface of the rotating electric fusion joint. The direction from (entrance) to heating wire supply hole 1210 (exit) is preferably the same as the direction in which the electric fusion joint rotates.

In addition, as shown in FIG. 2(C), in the step of forming the fused portion, the dedicated blade 1000 is moved in the axial direction (parallel movement is stopped) and the rotation of the electric fusion joint is stopped (rotation is stopped). It is preferable to further include a switching step of reversing the direction of the inner circumference of 1000 by 180 degrees to switch from the outward path to the homeward path (to form a turn portion T described later).
With reference to FIG. 2, the steps of forming the fused portion in this manufacturing method will be described separately for the forming of the outgoing winding and the forming of the returning winding.

As shown in FIG. 2(A), the dedicated blade 1000 is positioned at the starting position S of the forward pass, and is moved (translated) in the axial direction while being brought into contact with the inner peripheral surface of the electric fusion joint. At the same time, the rotation of the electrofusion joint (here, clockwise rotation as seen from the left opening) is started. By starting the parallel movement of the exclusive blade 1000 and the rotation of the electrofusion joint while bringing the exclusive blade 1000 into contact with the inner peripheral surface of the electrofusion joint in this way, the forward winding 300F is electrofused from the start position S. It begins to be embedded in the inner peripheral surface of the attachment joint.

By controlling the parallel movement speed of the special blade 1000 and the rotation speed of the electric fusion joint so as to form the forward winding shown in FIGS. A line 300F (specifically, the forward winding of either FIG. 7(A) or FIG. 8(A)) is formed.
Further, as shown in FIG. 2(C), the outward winding 300F shown in FIGS. 7 and 8 is formed until the dedicated cutter 1000 reaches the end position of the outward path (the starting position of the semicircle of the turn portion T). and execute the switching step. At this time, the parallel movement of the dedicated blade 1000 and the rotation of the electrofusion joint are stopped, and the direction of the inner peripheral direction of the dedicated blade 1000 is reversed by 180 degrees to form a turn portion T for switching from the outward path to the return path. be done.

Next, as shown in FIG. 3(A), the dedicated blade 1000 at the start position of the return path (the end position of the semicircle of the turn portion T) is brought into contact with the inner peripheral surface of the electrofusion joint and cut in the axial direction. Movement (parallel movement in the opposite direction of the forward path) is started, and rotation of the electrofusion joint (here, counterclockwise rotation as viewed from the left opening) is started. Parallel movement of the exclusive blade 1000 while the exclusive blade 1000 is brought into contact with the inner peripheral surface of the electrofusion joint in this way (parallel movement so as to bring the exclusive blade 1000 closer to the start position S in the opposite direction of the forward path) and By starting the rotation of the electric fusion joint (reverse rotation of the outward trip), the return winding 300R starts to be embedded in the inner peripheral surface of the electric fusion joint from the end position of the turn portion T.

By controlling the parallel movement speed of the special blade 1000 and the rotation speed of the electric fusion joint so as to form the return winding shown in FIGS. A line 300R (more specifically, the return winding in either FIG. 7(B) or FIG. 8(B)) is formed.
Furthermore, as shown in FIG. 3(C), when the return winding 300R shown in FIGS. are embedded in the inner peripheral surface of the electric fusion joint from the start position S to the end position E via the turn portion T as the outward winding 300F, the turn portion T and the return winding 300R.

<Structure of special blade>
Structural features of the dedicated blade 1000 used in the above-described electrofusion joint manufacturing method will be described in detail below with reference to FIGS. 5 and 6. FIG.
As described above, the special blade 1000 has a structure in which the press cutting blade 1200, the heating wire supply hole 1210, and the holding guide 1300 face the inner peripheral surface of the rotating electrofusion joint in this order. Furthermore, the shape of the press cutting blade viewed from the direction along the inner peripheral surface (the direction shown in FIGS. 5 and 6) is a substantially V shape, and the tip side of the substantially V shape contacts the inner peripheral surface and cuts. Cutting notched grooves.
Here, as shown in FIGS. 5 and 6, the axial length of the dedicated blade 1000 is blade width A, the axial width of the holding guide 1300 is holding guide width E, and the wire diameter of the heating wire 300 is diameter d2. As such, the blade width A and the presser guide width E are preferably ten times or more the diameter d2.

For the electrofusion joint with a nominal diameter of 250, the blade width A and the pressing guide width E described above were set to 10 mm, but when embedding the heating wire 300 by press cutting and when making a U-turn (when forming the turn portion T) Because the load on the dedicated blade 1000 was large and the push cutting blade 1200 was deformed and damaged, the blade width A and the holding guide width E were set to 15 mm for the purpose of improving strength. Here, the blade width A and the pressing guide width E may vary depending on the nominal diameter of the electric fusion joint. Attention is paid to the relationship with the diameter d2, which is the wire diameter of 300. This diameter d2 is generally preferably about 0.7 mm to 1.1 mm. For 0.7 mm, A = E = 15 mm, d2 = 0.7 mm and 15/0.7 = 21.42, and for 1.1 mm, A = E = 15 mm, d2 = 1. 15/1.1=13.64 at .1 mm, and both the blade width A and the presser guide width E are preferably at least 10 times the diameter d2.

Further, assuming that the length in the inner peripheral direction from the press cutting blade 1200 to the presser guide 1300 is the distance G, the wire diameter of the heating wire 300 is the diameter d2, the blade width A and the presser guide width E are four or more times the diameter d2. Preferably.
When comparing the distance G between 2 mm and 5 mm for an electrical fusion joint with a nominal diameter of 250, the shorter the embedding position of the heating wire 300 is shallower (the embedding position is closer to the inner surface of the joint and the heating wire can be visually observed). It can be seen and not hidden) is not preferable, and the longer one is preferable because the holding effect is greater (the heating wire cannot be visually confirmed and is hidden). Here, these distances G may change depending on the nominal diameter of the electric fusion joint, but in the present invention, it is the wire diameter of the heating wire 300 embedded in the inner peripheral surface of the electric fusion joint. Attention is paid to the relationship with the diameter d2. As described above, when the diameter d2 is 0.7 mm and 1.1 mm, in the case of 0.7 mm, G = 5 mm, d2 = 0.7 mm and 5/0.7 = 7.143, In the case of 1.1 mm, G=5 mm and d2=1.1 mm, 5/1.1=4.545, and the distance G is preferably at least four times the diameter d2.

Furthermore, assuming that the groove angle at the tip of the substantially V-shaped press cutting blade 1200 is an angle α, the angle α is preferably less than 80 degrees.
When comparing 80 degrees and 40 degrees as the angle α of the push cutting blade 1200 for an electrofusion joint with a nominal diameter of 250, the larger the angle α, the groove width at the time of U-turn (at the time of forming the turn portion T) becomes large, and the heating wire 300 tends to float out of the groove and easily come off the groove (because such a problem does not occur if the angle α becomes small). is preferred.

Furthermore, the width of the push cutting blade 1200 in the axial direction and the width on the side opposite to the tip side is the push cutting blade width B, the height of the approximately V-shaped push cutting blade 1200 is the pushing cutting blade height C, and the pushing cutting blade width B It is preferable that ≤ the height of the push cutting edge C x 0.75.
Regarding the groove angle (angle α) of the substantially V-shaped tip of the push cutting blade 1200, the following judgment can be made by considering it from another point of view. In order to prevent the problem that the groove width at the time of U-turn (at the time of forming the turn portion T) becomes large and the heating wire 300 floats out of the groove and easily comes off the groove in the electric fusion joint with a nominal diameter of 250. In the present invention, it is preferable that the width of the push cutting edge B≦the height of the push cutting edge C×0.75.
Furthermore, the width of the push cutting blade 1200 in the axial direction and the width on the side opposite to the tip side is the push cutting blade width B, the height of the substantially V-shaped push cutting blade 1200 is the push cutting blade height C, and the line of the heating wire 300 Assuming that the diameter is diameter d2, it is preferable that the push cutting edge width B is 2.8 times or less the diameter d2, and the push cutting edge height C is 3.6 times or more the diameter d2.

Regarding the groove angle (angle α) of the substantially V-shaped tip of the push cutting blade 1200, the following judgment can be made by considering it from another point of view. As described above, the problem that the groove width at the time of U-turn (at the time of forming the turn portion T) is increased for the electric fusion joint with the nominal diameter of 250, and the heating wire 300 floats out of the groove and is easily detached from the groove is solved. From the viewpoint of not generating it, there is a possibility that it changes depending on the nominal diameter of the electrofusion joint, but in the present invention, the outer dimensions of the push cutting blade 1200 (push cutting blade width B and push cutting blade height C, and the nominal Attention is focused on the relationship between B=3 mm and C=4 mm for a diameter of 250) and the diameter d2, which is the wire diameter of the heating wire 300 embedded in the inner peripheral surface of the electric fusion joint. As described above, when the diameter d2 is 0.7 mm and 1.1 mm, in the case of 0.7 mm, B/d2=3/0.7=4.285 (4.3: rounded up), C/ d2 = 4/0.7 = 5.714 (5.7: rounded down) and in the case of 1.1 mm, B/d2 = 3/1.1 = 2.727 (2.8: rounded up) , C/d2 = 4/1.1 = 3.636 (3.6: rounded down), the push cutting edge width B is 2.8 times or less than the diameter d2, and the pushing cutting edge height C is the diameter d2 is preferably 3.6 times or more.

Further, the length of the push cutting blade 1200 in the inner peripheral direction is defined as the push cutting blade length D, and the wire diameter of the heating wire 300 is defined as the diameter d2.
It is assumed that for an electrofusion joint having a nominal diameter of 250, the load at the time of a U-turn (at the time of forming a turn portion T) will be smaller if the push cutting edge length D is as short as possible. However, if the length is shortened, the rigidity of the press cutting blade 1200 is lowered, so it is preferable to secure a length of about 6 to 7 mm. Here, the press cutting blade length D may vary depending on the nominal diameter of the electric fusion joint. The focus is on the relationship with the diameter d2. As described above, when the diameter d2 is 0.7 mm and 1.1 mm, in the case of 0.7 mm, D = 6 to 7 mm, d2 = 0.7 mm and 8.57 (= 6/0.7) ~10 (=7/0.7), and in the case of 1.1 mm, 5.45 (=6/1.1) ~ 6.36 (=7/1.1). Also, the length D of the press cutting edge is preferably 10 times or less of the diameter d2.

Furthermore, the diameter of the heating wire supply part (more specifically, the diameter of the heating wire introduction hole 1110, the heating wire supply hole 1210, and the communication hole provided inside the dedicated blade 1000 that connects these holes with the same diameter The diameter of the heating wire supply hole 1210 may be represented by the diameter d1, and the wire diameter of the heating wire is the diameter d2.

Here, the relationship (difference, clearance) between the diameters d1 and d2 is basically the same for electrofusion joints having different nominal diameters. Regarding the diameter d2, which is the wire diameter of the heating wire 300, when the difference between the diameter d1, which is the diameter of the heating wire supply portion of the dedicated blade 1000, and the diameter d2, which is the wire diameter of the heating wire 300, is about 0.4 mm, The resistance when the heating wire 300 passed through the special blade 1000 was large, and the breakage of the heating wire was confirmed (diameter d1: 1.5 mm, diameter d2: 1.1 mm). When a clearance of about 0.8 mm was secured as the difference between them (diameter d1−diameter d2) (diameter d1: 1.5 mm, diameter d2: 0.7 mm), breakage of the heating wire 300 was not confirmed. For these reasons, it is preferable to secure a clearance approximately equal to the diameter d2 of the heating wire 300 .

<Winding structure>
The characteristics of the winding method used in the above-described method for manufacturing an electrofusion joint and the characteristics of the winding structure of the electrofusion joint manufactured by the method will be described in detail below with reference to FIGS. 7 to 9. explain. 7 and 8 are diagrams for explaining the winding structures of the electric fusion joint 100 and the electric fusion joint 200 according to the present embodiment, and FIG. 9 shows a comparative example for comparison with them. FIG. 4 is a diagram for explaining the electric fusion joint winding structure; 7 and 8, the positions of the turn portions T (pitch of the turn portions T) depend on the operating conditions of the electrofusion joint manufacturing apparatus according to the present embodiment (under the following conditions: (within a satisfactory range).

As described above, in the fusion part provided in the electric fusion joint, two terminal pins 2000 are arranged on the left and right sides, and a total of four terminal pins 2000 are arranged on the end side (not the center side in the axial direction) of the electric fusion joint. In order to do so, the outward path in which the spiral progresses in the outward direction from the opening side of the electric fusion joint 100 to the opening side on the opposite side of the opening and the return path in the direction opposite to the outward direction are windings that pass through the turn portion T. It has a winding structure in which one heating wire 300 is embedded by wire method. This winding structure has the following features.

The fused portion provided in the electric fusion joint has a first area in the center in the axial direction of the fused portion in which the helical pitch is formed with the same pitch in both the outward path and the return path, and the helical pitch is greater than the same pitch. and a second area other than the central portion which is formed with a maximum double pitch.
More specifically, the area of the fusion part provided in the electric fusion joint is divided into a first area in the center of the fusion part in the axial direction, and a start position S and an end of the heating wire 300 other than the first area, which is the center part. Divided into a second area including the position E and the turn portion T, the helical winding pitch in the first area is formed with the same pitch, and the helical winding pitch in the second area is the same as that of the first area. It is formed with a pitch twice as large as the same pitch.

As shown in FIG. 9, when the winding pitch of the second area is about 3 to 5 times the winding pitch of the first area, the heating wire 300 tends to move outward during fusion. There was a tendency for short-circuits to occur easily due to protrusion to the outside of the joint and contact of the heating wire on the outward and return paths. On the other hand, the change in the winding pitch of the second area is small with respect to the winding pitch of the first area (the winding pitch of the second area is the same as the same pitch of the first area, or the same pitch of the first area). 2 times the pitch at the maximum), there is a tendency that the heating wire 300 is less likely to protrude or short circuit. For this reason, it is preferable that the winding pitch of the second area is suppressed to be equal (including identical) to twice the winding pitch of the first area.

The winding pitch is divided into the first area and the second area, and shown below, although this is an example because it is the case of the electrical fusion joint with a nominal diameter of 250 shown in FIGS.
As shown in the outward winding of FIG. 9A, which is the winding structure of the electrofusion joint according to the comparative example, the outward processing pitch is F(n) to F(n+1)=9.0 mm ( n = 1 to 5), the second area is F(0) to F(1) = 14.5 mm and F(6) to F(7) = 20.5 mm (turn portion T), The winding pitch of the second area (here, F(6) to F(7) = 20.5 mm (turn portion T)) is the same pitch of the first area (here, F(n) to F(n+1) = 9.0 mm (n = 1 to 5)), so the winding pitch in the second area is not the same as the same pitch in the first area, but is the largest than the same pitch in the first area. I'm not satisfied with twice as much.

Also, as shown in the return winding in FIG. The area is R(0) to R(1)=35.0 mm and F(6) to F(7)=15.0 mm (turn portion T), and the winding pitch of the second area (here, R( 0) to R(1) of 35.0 mm) is 3.9 times the same pitch of the first area (here, R(n) to R(n+1) of 9.0 mm (n=1 to 5)). Because of this, the winding pitch of the second area is not the same as the same pitch of the first area, and is not at most twice as satisfying as the same pitch of the first area.

In the winding structure shown in FIG. 9, the heating wire 300 tends to move outward during fusion, protruding to the outside of the electric fusion joint, and short-circuiting due to contact of the heating wire in the outward and return paths. seen.
Next, as shown in the outward winding of FIG. 7A, which is the winding structure of the electric fusion joint 100 according to the present embodiment, the outward processing pitch is such that the first area is F(n) to F(n+1). ) = 13.0 mm (n = 0 to 3), the second area is F(4) to F(5) = 16.5 mm (turn portion T), and the winding pitch of the second area is , (same as the same pitch of the first area, or) at most twice the same pitch of the first area.

Also, as shown in the return winding in FIG. 7B, the return processing pitch is R(n) to R(n+1)=13.0 mm in the first area and the second area (n=0 to 6: turn portion and the winding pitch of the second area is the same as the same pitch of the first area (or twice the same pitch of the first area at most).
Furthermore, as shown in the outward winding in FIG. 8A, which is the winding structure of the electrofusion joint 200 according to the present embodiment, the outward processing pitch is F(n) F (n+1) = 13.0 mm (n = 0 to 5: including turn portions), and the winding pitch of the second area is the same as the same pitch of the first area (or the same pitch of the first area 2 times at most).

Also, as shown in the return winding in FIG. The area is R (5) to R (6) = 14.5 mm (turn part T), and the winding pitch of the second area is (same as the same pitch of the first area, or) It satisfies a maximum of twice the same pitch.
In the winding structure shown in FIG. 7 and the winding structure shown in FIG. 8, unlike the winding structure according to the comparative example shown in FIG. There was no tendency to protrude outward or to easily cause a short circuit due to contact of the heating wire on the outward and return trips.

The second area, which is divided into the first area and the second area as described above, includes a switching portion (turn portion T) from the outward path to the return path.
Furthermore, the pitch of this switching portion (turn portion T) is preferably equal to or greater than the same pitch of the first area.
In the case of an electrofusion joint with a nominal diameter of 250, as an example, the pitch of the switching portion (turn portion T) is the same pitch 13 in the first area as shown in the outward winding of FIG. 7(A). 0 mm, 16.5 mm, 13.0 mm for the same pitch 13.0 mm in the first area as shown in the return winding of FIG. 13.0 mm for the same pitch of 13.0 mm in the first area, and 14.5 mm for the same pitch of 13.0 mm in the first area as shown in the return winding in FIG. It is satisfied that the pitch of the portion (turn portion T) is equal to or greater than the same pitch of the first area.

In addition, as described above, the winding pitch of the second area is the same as the same pitch of the first area, or a maximum of twice the same pitch of the first area. The pitch of the switching portion (turn portion T) in 9 is 20.5 mm for the same pitch of 9.0 mm in the first area as shown in the outward winding of FIG. As shown by the line, it is 15.0 mm for the same pitch of 9.0 mm in the first area, and the pitch of the switching portion (turn part T) is satisfied that it is equal to or greater than the same pitch of the first area. . Therefore, if the winding structure in FIG. 9 is changed so that the winding pitch in the second area is the same as the same pitch in the first area, or is at most twice as large as the same pitch in the first area, The heating wire 300 tends to move outward during fusion, and it is possible to eliminate the tendency for the heating wire 300 to protrude to the outside of the electric fusion joint and to easily cause a short circuit due to the contact of the heating wire in the outward and return trips. can be realized.

The switching portion (turn portion T) is preferably formed by a semicircle with a diameter larger than half of the same pitch in the first area.
The switching portion (turn portion T) is preferably formed by a semicircle with a diameter of 150% or more of the half of the same pitch in the first area.
is preferred.

In the case of an electrofusion joint with a nominal diameter of 250, as an example, the diameter of the semicircle of the switching portion (turn portion T) is 10.0 mm for the same pitch of 13.0 mm, 10.0 mm for the same pitch of 13.0 mm in the first area as shown in the return winding of FIG. 7B, and the forward winding of FIG. 10.0 mm for the same pitch of 13.0 mm in the first area, and 10.0 mm for the same pitch of 13.0 mm in the first area as shown in the return winding of FIG. The switching part (turn part T) is a semicircle with a diameter larger than half of the same pitch in the first area, and a semicircle with a diameter of 150% or more of the half of the same pitch in the first area. be satisfied.

In addition, as described above, the winding pitch of the second area is the same as the same pitch of the first area, or a maximum of twice the same pitch of the first area. The diameter of the semicircle of the switching portion (turn portion T) in 9 is 10.0 mm for the same pitch of 9.0 mm in the first area as shown in the outward winding of FIG. 10.0 mm for the same pitch of 9.0 mm in the first area as shown in the return winding, and the switching part (turn part T) is half the diameter larger than half of the same pitch in the first area. We are satisfied with the circle and the semicircle with a diameter of 150% or more for half the same pitch in the first area. Therefore, if the winding structure in FIG. 9 is changed so that the winding pitch in the second area is the same as the same pitch in the first area, or is at most twice as large as the same pitch in the first area, The heating wire 300 is easily moved to the outside during fusion, and it is possible to eliminate the tendency of the electric heating wire 300 to protrude to the outside of the electric fusion joint and to easily cause a short circuit due to the contact of the heating wire in the outward and return trips. can be realized.

<Terminal pin structure>
Structural features of the terminal pin 2000 that constitutes the electrofusion joint described above will be described in detail below with reference to FIG.
As described above, the electric fusion joint according to the present embodiment does not provide a crossover portion on the central portion side in the axial direction as in Patent Document 1, and separates the left and right heating wires so that the left and right heating wires are separated. A total of four terminal pins 2000 are arranged two each on the end side of the electric fusion joint, and a through hole for providing the terminal pin on the central side (the outer peripheral surface and the inner peripheral surface of the sleeve It has a feature that it does not affect watertightness because it does not have a hole through which the This terminal pin 2000 is formed by cutting a helical groove with a press cutting edge 1200 of a dedicated blade 1000, and at the same time inserting a heating wire into the groove (after the steps shown in FIGS. 2 and 3). The terminal pin 2000 shown in FIG. As described above, the terminal pin 2000 included in the electric fusion joint according to the present embodiment has a structure that is reliably connected to the heating wire 300 embedded in the inner peripheral surface.

A terminal pin 2000 shown in FIG. 10(A) and a terminal pin 2100 shown in FIG. 10(B) are terminal pins provided in the electric fusion joint according to the present embodiment. , and the shape of the groove that includes the heating wire 300 along the longitudinal direction of the heating wire 300 is different. The terminal pin 2000 shown in FIG. 10A has a non-tapered groove 2032, and the terminal pin 2100 shown in FIG. 10B has a tapered groove 2132 with a taper. Only this point is different between the terminal pin 2000 and the terminal pin 2100 . In addition, FIG. 10(C) shows a procedure for providing a hole for inserting a terminal pin and inserting the terminal pin into the hole to include the heating wire 300 in the groove provided at the end 2030 on the heating wire 300 side, A procedure for reliably connecting the terminal pin and the heating wire 300 will be shown. Note that the terminal pin 2000 and the terminal pin 2100 may be represented by the terminal pin 2000 in the description.

This terminal pin 2000 is inserted into a hole drilled so as to reach the heating wire 300 from the outer peripheral surface of the thermoplastic resin pipe (tube material, sleeve), and supplies electricity to the heating wire 300 from an external power supply. It has a substantially cylindrical shape and is electrically conductive (an example is using copper, lead, etc. as the material of the terminal pin). An end portion 2030 of the terminal pin 2000 on the side of the heating wire 300 (this end portion 2030 is more specifically a substantially cylindrical lower end face) encloses the heating wire 300 along the longitudinal direction of the heating wire 300. A groove 2032 (a tapered groove 2132 in the case of the terminal pin 2100) is provided, and the terminal pin and the heating wire are in contact with each other at a position on the outer peripheral surface side of the thermoplastic resin pipe opposite to the end of the terminal pin 2000. A mark indicating the direction of the groove 2032 (or the tapered groove 2132) is attached at a position visible from the outer peripheral surface of the thermoplastic resin pipe when in contact. In this case, this mark indicates the direction of the groove 2032 (or the tapered groove 2132), and also indicates the outer peripheral surface of the thermoplastic resin pipe when the terminal pin 2000 (or the terminal pin 2100) and the heating wire 300 are in contact with each other. Since the heating wire 300 can be seen from the outside, the heating wire 300 can be surely enclosed in the groove 2032 (or the tapered groove 2132).

This mark is a marking groove in the same direction as the groove 2032 (or tapered groove 2132) provided at the end portion 2010 on the outer peripheral surface side (this end portion 2010 is more specifically the substantially cylindrical upper end surface). 2012 is preferred. In this case, as shown in FIGS. 10A and 10B, the groove 2032 (or tapered groove 2132) and the marking groove 2012 are in the same direction, and the marking groove 2012 is aligned with the terminal pin 2000 (or Since the contact between the terminal pin 2100 and the heating wire 300 can be seen from the outer peripheral surface of the thermoplastic resin pipe, the heating wire 300 can be reliably included in the groove 2032 (or the tapered groove 2132). can.

The cross-sectional shape of the tapered groove 2132 is preferably a substantially inverted V shape in which the groove width on the groove open side is wider than the groove width on the groove bottom portion. As a result, it is possible to more reliably prevent poor conduction when connecting and fusing the heating wire 300 and the terminal pin 2000 by soldering.
As described above, the terminal pin 2000 shown in FIG. 10(A) and the terminal pin 2100 shown in FIG. 10(B) are substantially cylindrical and have conductivity, and the end 2030 (lower end face) on the heating wire 300 side is provided with a groove 2032 (or tapered groove 2132) containing the heating wire 300 along the longitudinal direction of the heating wire 300, and at the position on the outer peripheral surface side of the thermoplastic resin pipe on the opposite side to the end 2030 A mark in the same direction as the groove 2032 (or the tapered groove 2132) is placed at a position (end portion 2010 (upper end surface)) visible from the outer peripheral surface of the thermoplastic resin pipe when the terminal pin and the heating wire are in contact. A groove 2012 is provided. Further, a collar 2020 is provided at an intermediate portion between the end portion 2010 (upper end surface) and the end portion 2030 (lower end surface) to prevent it from coming off.

A procedure for installing the terminal pin 2000 having such a configuration will be described with reference to FIG. 10(C). In the procedure described below, (C1) to (C3) are performed before forming the windings, and (C4) to (C5) are performed after forming the windings (after the steps shown in FIGS. 2 and 3). be implemented. As for the dimensions of each part, an electrical fusion joint with a nominal diameter of 250 is taken as an example.

(C1) A hole having a diameter corresponding to the size (diameter) of the flange 2020 is drilled from the outer peripheral surface to the inner peripheral surface of the electrofusion joint 100 . At this time, the depth of the hole is determined according to the position of the collar 2020 . For example, a 10 mm diameter hole is drilled for a maximum diameter of collar 2020 of 10.5 mm. Also, the lowermost end of the flange 2020 is positioned 15 mm from the upper end face of the terminal pin 2000, and a hole with a depth of 18 mm is drilled.
(C2) Stop the drill at the depth determined in (C1) above, and chamfer the periphery of the hole on the outer peripheral surface. For example, chamfer at 2 mm.

(C3) A hole having a diameter corresponding to the size (diameter) of the terminal pin 2000 below the flange 2020 of the terminal pin 2000 is drilled from the outer peripheral surface to the inner peripheral surface of the electrofusion joint 100 . For example, the size (diameter) below the flange 2020 is 5 mm to 6 mm, and a hole with a diameter of 8 mm is made to penetrate to the inner peripheral surface. (C4) and (C5) after this are processes after the winding process shown in FIGS. (C4) Insert the terminal pin 2000 into the through hole. At this time, the mark groove 2012 is visually confirmed, and the groove 2032 provided in the same direction as the mark groove 2012 includes the heating wire 300 (the longitudinal direction of the heating wire 300 and the mark groove 2012 are parallel to each other). The terminal pin 2000 is inserted into the through-hole such that the groove 2032 includes the heating wire 300 in a positive position.

(C5) The terminal pin 2000 is inserted into the through-hole and the heating wire 300 is soldered to the terminal pin 2000 with the heating wire 300 enclosed in the groove 2032 to connect the terminal pin 2000 and the heating wire 300 .
Thus, the heating wire 300 enclosed in the groove 2032 (or the tapered groove 2132) and the terminal pin 2000 (or terminal pin 2100) are connected by soldering (although this is one example). However, the present invention is not limited to such connection by soldering, and the following connection can be adopted. Connections other than soldering will be described with reference to FIGS. 10(D) and 10(E). Although FIGS. 10(D) and 10(E) describe the connection between the heating wire 300 and the terminal pin 2100, the terminal pin 2000 may be used instead of the terminal pin 2100. FIG.

As shown in FIGS. 10(D) and 10(E) , the connection between the terminal pin 2100 and the heating wire 300 in the tapered groove 2132 is a conductive wire having a shape that matches the shape of the tapered groove 2132 or the shape of the heating wire 300 . It is preferable that a flexible connecting member is brought into contact with and joined to the terminal pin 2100 and the heating wire 300 .
As such a connection member, as shown in FIG. 10(D), the connection member 2210 has a substantially hollow cylindrical shape that has a hollow portion that includes a cross-sectional shape in a vertical plane in the longitudinal direction of the heating wire 300 and that matches the groove width. Alternatively, as shown in FIG. 10E, the connecting member 2220 may have a substantially prismatic shape that matches the width of the groove. Note that the terminal pin 2100 is preferable to the terminal pin 2000 because, once the connection member 2210 and the connection member 2220 are fitted into the tapered groove 2132 , it is difficult for them to come out of the tapered groove 2132 .

<Action and effect of the above-described embodiment>
According to the method for manufacturing an electrofusion joint and the electrofusion joint having the above-described configuration, the following effects are obtained.
(1-1) Injection molding equipment and dedicated heating wire winding are used to install (embed) the heating wire on the inner peripheral surface by attaching a dedicated blade to a general-purpose ordinary lathe or NC lathe and rotating the sleeve. It is possible to install and fix the heating wire without using processing equipment. In particular, in the case of injection molding, a dedicated mold for each size is required. It becomes possible to manufacture electric fusion joints.
(1-2) By notching the inner peripheral surface of the sleeve with a pressing blade and inserting the heating wire while advancing the dedicated blade along the inner peripheral surface, it is possible to fix the heating wire when it passes through the holding guide. In addition, grooving, heating wire installation, and fixing can be performed in a single process. As a result, it is possible to shorten the manufacturing time.
(1-3) Since it is possible to relatively easily change the height of the press cutting blade and the diameter and position of the hole through which the heating wire passes in the special blade, It is possible to arbitrarily and relatively easily adjust the insertion depth and the heating wire diameter.
(1-4) Since the shape of the press cutting blade can be relatively easily changed to a "conical shape" other than "substantially V-shaped", when the winding pitch of the heating wire is greatly changed or the winding direction is extremely changed (such as when the turn portion T is formed by reversing 180°), it is possible to suppress the resistance acting on the press cutting blade.

(2) In the electric fusion joint according to the present embodiment, the areas of the fusion part are the first area at the center in the axial direction of the fusion part, and the heating wire other than the first area, which is the center. Divided into a start position, an end position, and a second area including a turn portion, the spiral winding pitch in the first area is formed with the same pitch, and the spiral winding pitch in the second area is the first area. A winding structure was adopted in which the pitch is at most twice as large as the same pitch in the area. That is, the winding pitch near the joint inlet (end) and the turn (second area), which is a general winding structure in an electric fusion joint, is compared to the central part (first area) of the fusion. It is not so large, but because it does not exceed twice the maximum (in order not to increase the winding pitch), it is difficult for the heating wire to move outward during fusion, and it does not protrude to the outside of the electric fusion joint. There was a tendency that a short circuit due to the contact of the heating wire on the outbound and inbound trips was less likely to occur. Furthermore, even if the joining quality is not significantly affected, suppressing the protrusion of the heating wire from the electric fusion joint leads to an improvement in appearance. In addition, when the heating wire is wound, if the winding pitch is increased, the load acting on the press cutting blade of the special cutting tool increases due to the force acting in the oblique direction. Keeping the winding pitch the same or not exceeding twice leads to suppression of wear and deformation of the press cutting blade of the dedicated blade.

(3) When inserting the terminal pin into the hole (during driving), if the terminal pin rotated and the heating wire did not fit in the groove, the terminal pin could not be securely connected to the heating wire. A mark indicating the direction of the groove (marking groove) is attached at a position visible from the outer peripheral surface of the electric fusion joint, so it is possible to check whether the terminal pin is rotating during insertion of the terminal pin and ensure the heating wire. can be enclosed in the groove. In addition, by connecting the terminal pin to the heating wire by means other than soldering, it is possible to more reliably avoid a situation in which the solder comes off during the energization process and the electrical fusion process is interrupted. As a result, the terminal pin and the heating wire can be reliably connected, thereby preventing fusion troubles at the construction site.

It should be considered that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present invention includes all changes within the meaning and range of equivalents of the claims, and includes, for example, the following three modifications.
As a first modification, a terminal pin 2300 having structural features different from those of the terminal pin 2000 constituting the electrofusion joint described above will be described in detail below with reference to FIG. In the following description of the terminal pin 2300 according to this modified example, the same reference numerals are given to the structures common to the terminal pin 2000 or the terminal pin 2100 shown in FIG. Detailed description will not be repeated.
A terminal pin 2300 shown in FIG. 11A is used in combination with a connection pin 2400 shown in FIG. It has a structure for reliably connecting with the heating wire 300 inserted (embedded) in the formed notch groove.

In this modification, as a structure for reliably connecting the terminal pin 2300 to the heating wire 300, a through hole is drilled so as to reach the heating wire 300 from the outer peripheral surface of the thermoplastic resin pipe (tube material, sleeve). (Synonymous with through-hole), a substantially cylindrical and conductive terminal pin for supplying electricity from an external power supply to the heating wire 300 (an example of using copper, lead, etc. as a material of the terminal pin) 2300 , and a conductive connection pin 2400 connecting the terminal pin 2300 and the heating wire 300 . The connection pin 2400 is formed by bending a metal piece, and has a hollow cylindrical portion 2410 on the terminal pin 2300 side that is fitted into a substantially cylindrical shape, and a crimping portion 2430 that crimps the heating wire 300 on the heating wire 300 side. The size (diameter) and length of the hollow cylindrical portion 2410 of the connecting pin 2400 are determined so that the hollow cylindrical portion 2410 of the connecting pin 2400 can be fitted into the substantially cylindrical portion 2330 of the terminal pin 2300. It corresponds to the size (diameter) and length of the substantially cylindrical portion 2330 of the pin 2300 . Further, the distal end of the substantially cylindrical portion 2330 is provided with a taper 2332 in order to insert the connecting pin 2400 into the terminal pin 2300 more easily.

Then, the crimp portion 2430 of the connection pin 2400 is folded back at the end of the connection pin 2400 on the side of the heating wire 300, and the heating wire 300 inserted between the folded metal pieces (FIG. 11 ( Crimping and crimping are performed using a crimping tool or electric pliers, etc., as indicated by the black arrows shown in (D3) of D).
Also, although not limited, the connection pin 2400 can employ a receptacle terminal such as the plan view shown in FIG. 11(B) and the perspective view shown in (D1) of FIG. 11(D). . Here, the connection pin 2400 (receptacle terminal here, although not limited thereto) is formed continuously by bending a piece of metal (a thin metal plate) as shown in (B1) of FIG. 11(B). It has a shape in which a hollow cylindrical portion 2410 and a crimping portion 2430 are connected by a connecting portion 2420 by being cut by a dotted line.

A procedure for connecting the terminal pin 2300 and the heating wire 300 using the connection pin 2400 having such a configuration will be described with reference to FIG. 11(C). Note that (C1) to (C3) are the same as in FIG. 10 described above, and therefore will not be described repeatedly.
(C4) Insert the terminal pin 2300 into the through hole. By this time, or after this time, as a crimping step, as shown in (D1) to (D3) in FIG. The end of the heating wire 300 inserted into the formed notch groove is crimped to the crimping portion 2430 of the connection pin 2400 . At this time, as described above, the heating wire 300 inserted between the folded metal pieces (as indicated by the black arrows in FIG. (using) to crimp and crimp.

(C5) As a connecting step, the hollow cylindrical portion 2410 of the connecting pin 2400 with the end of the heating wire 300 crimped to the crimping portion 2430 (as indicated by the gray arrow) is connected to the substantially cylindrical portion 2330 of the terminal pin 2300. so that the terminal pin 2300 and the heating wire 300 are connected via the connection pin 2400 in the through hole.
In this way, the hollow cylindrical portion 2410 of the connection pin 2400, in which the end portion of the heating wire 300 is crimped to the crimping portion 2430, is fitted into the substantially cylindrical portion 2330 of the terminal pin 2300 without soldering or the like. , the end of the heating wire 300 is securely connected to the terminal pin 2300 .

As a second modification, a terminal pin 2500 having structural features different from those of the terminal pins 2000 and 2300 constituting the electrofusion joint described above will be described in detail below with reference to FIG. In the following description of terminal pin 2500 according to the present modification, the same reference numerals are used for configurations common to terminal pin 2000 or terminal pin 2100 shown in FIG. 10 and terminal pin 2300 shown in FIG. and a detailed description thereof will not be repeated here.
A terminal pin 2500 shown in FIG. 12(A) is used in combination with a connecting cylinder 2600 shown in FIG. The heating wire 300 is inserted (embedded) into a notch groove formed in a shape and is reliably connected.

In this modification, as a structure for reliably connecting the terminal pin 2500 to the heating wire 300, a through hole is drilled so as to reach the heating wire 300 from the outer peripheral surface of the thermoplastic resin pipe (tube material, sleeve). (Synonymous with through-hole), a substantially cylindrical and conductive terminal pin for supplying electricity from an external power supply to the heating wire 300 (an example of using copper, lead, etc. as a material of the terminal pin) 2500 , and a conductive connection cylinder 2600 that connects the terminal pin 2500 and the heating wire 300 . The terminal pin 2500 has a substantially cylindrical portion 2530, and the curved surface of the substantially cylindrical portion 2530 is provided with a groove corresponding to the diameter of the heating wire 300 and a side groove 2530S along the central axis of the substantially cylindrical shape. The connecting cylinder 2600 is formed by bending a metal piece into a substantially cylindrical shape, and the terminal pin 2500 having the heating wire 300 enclosed in the side groove 2530S is inserted into the substantially cylindrical portion of the connecting cylinder 2600. , and the heating wire 300 is pressed against the terminal pin 2500 . In addition, the substantially cylindrical shape of the connecting cylinder 2600 is inserted into the substantially cylindrical portion 2530 of the terminal pin 2500 that includes the heating wire 300 in the side groove 2530S so that the heating wire 300 can be pressed against the terminal pin 2500. The size (diameter) and length correspond to the size (diameter) and length including the heating wire 300 enclosed in the side groove 2530S. Further, the tip of the substantially cylindrical portion 2530 is provided with a taper 2532 in order to insert the connecting cylinder 2600 into the terminal pin 2500 more easily.

In addition to the side groove 2530S provided in the substantially cylindrical curved surface of the substantially cylindrical portion 2530 of the terminal pin 2500, the grooves in which the heating wire 300 is enclosed include the substantially cylindrical portion 2530 of the heating wire 300 of the substantially cylindrical portion 2530. It is also preferable to provide an end face groove 2530E on the end face of the substantially cylindrical column on the side.
In addition, the connection cylinder 2600 can employ a crimp terminal or a terminal processed from the crimp terminal. Here, the crimp terminal is, for example, a terminal called bare crimp terminal for copper wire specified by JIS C 2805, for example. Here, in the case of a crimp terminal such as a round crimp terminal, a Y-shaped crimp terminal, and a rod-shaped crimp terminal, for example, as shown in (B2) of FIG. In the case of a round crimp terminal, the round part, in the case of a Y-shaped crimp terminal, the Y-shaped part, and in the case of a rod-shaped crimp terminal, the rod-shaped part) are cut to form only the crimped part. Moreover, in the case of a crimp terminal called a crimp sleeve, since it does not have the dotted line portion shown in (B2) of FIG. 12B, it can be used without processing. In this way, a crimp terminal or a terminal processed from a crimp terminal can be used as the connection cylindrical body 2600 .

A procedure for connecting the terminal pin 2500 and the heating wire 300 using the connecting cylinder 2600 having such a configuration will be described with reference to FIGS. 12(C) and 12(D). Note that (C1) to (C3) are the same as in FIG. 10 described above, and therefore will not be described repeatedly.
(Pre-process of C4) As an enclosing step, the end of the heating wire 300 inserted into the notch groove formed in a spiral shape on the inner peripheral surface of the thermoplastic resin pipe (tube material, sleeve) is attached to the terminal pin 2500. It is included in the groove (side groove 2530S or side groove 2530S and end groove 2530E). At this time, the end of the heating wire 300 is wrapped around the substantially cylindrical portion 2530 of the terminal pin 2500 to be included in the groove, as indicated by the gray arrow in (D1) of FIG. 12(D). Next, as indicated by the gray arrow in (D2) of FIG. 12(D), the substantially cylindrical portion 2530 of the terminal pin 2500 in which the heating wire is enclosed in the groove is attached to the substantially cylindrical connecting cylinder 2600. to press the heating wire 300 against the terminal pin 2500 . At this time, although not limited, for example, as indicated by the black arrows shown in (D3) of FIG. 300 is preferably pressed against the terminal pin 2500, but in the present invention, the substantially cylindrical portion of the connecting cylinder 2600 is inserted into the terminal pin 2500, which includes the heating wire 300 in the side groove 2530S. The terminal pin 2500 and the heating wire 300 are reliably connected simply by pressing the heating wire 300 against the terminal pin 2500 .

(C4) (C5) As a connecting step, the end of the heating wire 300 contained in the groove of the terminal pin 2500 (the side groove 2530S, or the side groove 2530S and the end face groove 2530E) is crimped by the connecting cylinder 2600. The terminal pin 2500 is inserted into the through-hole as indicated by gray arrows (C4) and (C5) in FIG. 2500 and the heating wire 300 are connected.

In this way, the heating wire 300 contained in the groove of the terminal pin 2500 (the side groove 2530S, or the side groove 2530S and the end face groove 2530E) and the connecting cylindrical body 2600 are brought into pressure contact, and soldering or the like can be used. The end of the heating wire 300 is securely connected to the terminal pin 2500.
The step of inserting and press-contacting the connecting cylinder 2600 into the terminal pin 2500 having the heating wire 300 enclosed in the groove (side groove 2530S, or side groove 2530S and end groove 2530E) is the same as in the second modification. Similarly, the present invention does not exclude the execution within the through-hole as in (C4) of FIG. 11(C). That is, in the through hole, the substantially cylindrical portion of the connection cylinder 2600 is inserted into the terminal pin 2500 having the heating wire 300 enclosed in the side groove 2530S so that the heating wire 300 is pressed against the terminal pin 2500. I don't mind.

<Third Modification: Inner Peripheral Surface Structure of Electrofusion Joint (Opening Side and Central Side)>
As a third modified example, an electric fusion joint 250 having structural features of the inner peripheral surface other than the fused portion of the electric fusion joint described above will be described in detail below with reference to FIGS. 13 and 14. do. The winding structure of the electric fusion joint 250 according to the present modification is obtained by cutting the return path of the winding structure of the electric fusion joint 100 shown in FIG. Like the winding structure of the electric fusion joint 200 shown in FIG. 8 (unlike the winding structure of the electric fusion joint 100 shown in FIG. 7), the axial direction is set between the start position S side and the end position E side. They are arranged at substantially the same position but shifted in the circumferential direction. Other winding structures in the electrofusion joint 250 have the same reference numerals as those of the electrofusion joint 100 shown in FIG. and FIG. 14, and detailed description thereof will not be repeated here.

Structural features (concave portions 252 and convex portions 254) of the electric fusion joint 250 according to this modified example, which will be described in detail below, other than the fusion-bonded portion on the inner peripheral surface are the same as the electric fusion joint 100 and the electrical It does not mean that it cannot be applied to the fusion joint 200, but that it can be applied to any electrofusion joint having a fusion portion, including the electrofusion joint 100, the electrofusion joint 200, and the electrofusion joint 250. be.

As shown in FIGS. 13 and 14, this electrofusion joint 250 (similar to the electrofusion joints 100 and 200) is a thermoplastic resin pipe ( A fused portion is provided in which a heating wire 300 is inserted into a notch groove formed in a spiral shape on the inner peripheral surface of a pipe member, sleeve). This fusion portion is provided on at least one (here, both) end portion side of the electric fusion joint 250 in the axial direction so that the electric heating wire 300 can be energized (via the terminal pin 2000 or the like).

In this fusion part, one heating wire has an outward path in which the spiral progresses in the outward direction from the opening side of the electric fusion joint 250 to the opening side on the opposite side of the opening, and a return path in the direction opposite to the outward direction. 300. As a structural feature of the electrical fusion joint 250 other than the fused portion on the inner peripheral surface, the inner peripheral surface on the opening side of the fused portion is provided with a concave portion 252 in which the inner peripheral surface is recessed.
And this recessed part 252 is provided over one round of inner periphery.
Furthermore, this recess 252 also serves as a handle for the electrofusion joint 250 .
With such a configuration, the following problems can be solved.

(A) When the resin pipe (resin pipe) of the connection partner and the electric fusion joint 250 are electrically fused, the clearance between the resin pipe and the electric fusion joint 250 is small, or the clearance is provided (supplied) by electric fusion. ), the resin may be excessively melted, and the excessively melted resin leaks from between the end face of the electric fusion joint 250 and the resin pipe of the connection partner, resulting in poor appearance. Bad problems may occur. In order to solve such a problem, the concave portion 252 whose inner peripheral surface is recessed is provided on the opening side (here, both ends) of the inner peripheral surface of the electric fusion joint 250, so that the excessively melted resin is filled in the concave portion 252 to prevent resin from leaking from the end face of the electric fusion joint 250 and to reduce the amount of leaking resin.
(B) When the electric fusion joint 250 is handled (during production and construction), the electric fusion joint 250 may be difficult to carry because it has no handle. In order to solve such a problem, a concave portion 252 having a concave inner peripheral surface is provided on the opening side of the inner peripheral surface of the electric fusion joint 250 (here, both ends). It becomes possible to put a finger on it, and the workability of carrying can be improved.

Further, the electrical fusion joint 250 has a protruded (rib-shaped) protrusion 254 on the inner peripheral surface on the central side of the electrical fusion joint 250 in the axial direction from the fusion portion.
And this convex part 254 is provided over one round of inner circumference.
With such a configuration, the following problems can be solved.

(C) When the resin pipe (resin pipe) of the connection partner and the electric fusion joint 250 are electrically fused, the clearance between the resin pipe and the electric fusion joint 250 is small, or the clearance is provided (supplied) by electric fusion. ), the resin may be melted excessively. The molten resin may flow toward the center, or the molten resin may push the heating wire in the fused portion out of the notch groove, exposing the heating wire 300, making it impossible to insert the resin pipe from the opposite side. Or there may be a problem that it becomes difficult. In order to solve such a problem, the protrusion 254 protruding from the inner peripheral surface is provided on the inner peripheral surface on the central side of the electric fusion joint 250 in the axial direction from the fused portion. It is possible to prevent the resin from flowing beyond the convex portion 254 to the opposite side (the side where the resin pipe is not inserted) (the rib-shaped convex portion 254 can be blocked), and the heating wire 300 can be prevented from flowing from the notch groove. Even if it jumps out, it can be prevented from flowing to the opposite side (the side where the resin pipe is not inserted) (the rib-shaped projection 254 can block it). Therefore, it is possible to suppress the flow of the molten resin and/or the heating wire 300 from the center side of the electrofusion joint 250 to the opening on the opposite side, and the resin pipe can be inserted from the opening on the opposite side. It becomes possible to prevent troubles of resin pipe insertion at the construction site.

As described above, according to the electric fusion joint and the method for manufacturing the electric fusion joint according to the present embodiment, including the modifications, the heating wire is inserted into the concave groove formed in the inner peripheral portion of the thermoplastic resin pipe. An electrofusion joint with a structure that is characterized by the fact that plastic pipes are not inserted into both the left and right sockets at once, but one of the left and right sockets (even if both the left and right are electrofused, only one of the left and right is electrofused). It does not matter if the other is electrofusion), it does not affect the watertightness without increasing the manufacturing cost, and the connection between the terminal pin and the heating wire is more reliable, so that troubles during construction or It is possible to provide an electrofusion joint that can be electrofused while avoiding the difficulty of transportation.

It should be noted that the embodiments including the modified examples disclosed this time should be considered as examples in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

The present invention is preferable for an electric fusion joint having a structure in which a heating wire is inserted into a groove formed in the inner circumference of a thermoplastic resin pipe. Manufacture of electric fusion joints that can be electrofused one by one on the left and right sockets (even if both the left and right are electrofused, only one of the left and right sides need not be electrofused). It is particularly preferable in that the connection between the terminal pin and the heating wire can be made more reliable without increasing the cost and the watertightness is not affected, thereby avoiding troubles during construction or difficulty in transportation.

REFERENCE SIGNS LIST 100 electric fusion joint 200 electric fusion joint 250 electric fusion joint 300 heating wire 300F outward winding 300R return winding 1000 dedicated blade 1100 body portion 1110 heating wire introduction hole 1200 push cutting blade 1300 holding guide 1600 housing joining portion 2000, 2300 , 2500 terminal pin 3000 indicator

Claims (3)

An electric fusion joint having a fusion part in which a heating wire is inserted into a notch groove formed in a spiral shape on the inner peripheral surface of a thermoplastic resin pipe into which a resin pipe to be connected is inserted,
The fusion part is provided on at least one end side of the electric fusion joint in the axial direction so that the electric heating wire can be energized,
In the fusion part, there is one outward path in which the spiral progresses in the outward direction from the opening side of the electric fusion joint to the opening side opposite to the opening, and one return path in the direction opposite to the outward direction. formed of heating wire,
An electric fusion joint, characterized in that the inner peripheral surface on the side of the opening side of the fusion-bonded portion is provided with a concave portion formed by recessing the inner peripheral surface. 2. The electric fusion joint according to claim 1, wherein the recess is provided along the inner periphery. 3. The electrofusion joint according to claim 1, wherein the recess also serves as a handle of the electrofusion joint.

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