JP2963082B2 - Electrofusion-type plastic pipe joint, method of manufacturing the same, and winding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrofusion-type plastic pipe joint, a method of manufacturing the same, and an automatic winding apparatus suitable for manufacturing the same.

[0002]

2. Description of the Related Art As a method for connecting a pipe made of a thermoplastic resin material such as polyethylene or polybutene to a gas pipe, water distribution, water supply, hot water supply pipe, etc., an electric fusion method using an electric fusion plastic pipe joint is known. Are known. FIG. 2 shows a connection state at this time. A pipe 7 is inserted into an electrofusion-type plastic pipe joint (hereinafter simply referred to as a joint) 10, and a controller (not shown) is connected to the connector pins 5 at both ends. Connect and supply the prescribed electrical energy,
The joint 10 and the pipe 7 are melted and fused by the heating action of the heating wire 3. Generally, the joint 10 includes an inner cylindrical member 1 made of a thermoplastic plastic called an inner,
An outer cylindrical member 6 of a thermoplastic plastic called an outer provided so as to wrap the inner 1, a heating wire 3 wound around a spiral groove 2 formed in the inner 1, and a metal wire connected to both ends of the heating wire 3 individually. And the connector pin 5.

[0003] The method of manufacturing the joint 10 includes an inner molding step of injection-molding the inner 1 forming the inner peripheral surface of the joint 10 and a pin attaching step of attaching connector pins 5 to seats provided at both ends of the inner 1. A first joining step of joining the distal end of the heating wire 3 to one of the connector pins 5; a winding step of winding the heating wire 3 around the spiral groove 2 of the inner 1 while applying a predetermined tension; It is well known that the method comprises a second joining step of joining the rear end of the heating wire 3 to the other connector pin 5 and an outer molding step of injection molding an outer 6 on the outer periphery of the inner 1 on which the heating wire 3 is wound. Have been. The method of joining the connector pin 5 and the heating wire 3 in the first and second joining steps includes a method in which a heating wire is simply wound around the connector pin a plurality of times, and a method disclosed in Japanese Utility Model Application Laid-Open No. H5-220957.
As shown in FIG. 3, as shown in FIG. 3, a connector pin 5 is provided with two flange-shaped flanges, a heating wire 3 is wound between the flanges, and then the collars are crimped together. . In addition, the method of applying tension to the heating wire 3 in the winding step includes a device that applies a frictional resistance load such as an electromagnetic brake or a powder brake.
Combined with the heating wire sending shaft or the contact roll shaft around which the heating wire is wound one or more times in the middle of the heating wire traveling path,
Generally, the load is applied to the heating wire 3 as tension.

[0004]

As described above, the fusion of the joint and the pipe is performed by the heating action of the heating wire 3 by the supplied electric energy. Conventional fusion control
This is a method in which a constant electric power is supplied until the inside of the joint is brought into a predetermined molten state, and is performed by sensing a temperature or the like. In this method, the current may be supplied until a predetermined melting state is reached. Even if the resistance value of the heating wire affecting the calorific value differs to some extent or varies, there is no particular problem in the fusion performance. Further, even if there is a connection failure between the connector pin and the heating wire, the connection failure can be detected, so that the execution failure does not occur. On the other hand, in recent years, water use is particularly remarkable. However, due to demands for simplification of the structure of the joint itself, cost reduction, and simplification of the controller and cost reduction, fusion control such that the energization time is constant. Methods are also being sought. In this case, in order to obtain a predetermined molten state, it is important that the connector pin and the heating wire are securely joined and the resistance value of the heating wire is a predetermined value. The variation also affects the quality of the fusion quality. Therefore, it is required that the joint be able to normally energize the current-carrying part and have a resistance value within a predetermined value range.

When the resistance value of the current-carrying part of the joint manufactured by the conventional manufacturing method was measured, it was found that the specific resistance of the heating wire was 1%.
Some of them fluctuated by about 0%, and this was mainly caused by the joining step and the winding step. Here, the specific resistance value is a resistance value measured when no tension is applied to a predetermined total length required for the winding of the joint. In the joining process, the joining condition of the joining portion is unstable and the joining force is weak, and the heating wire is displaced when winding with applying tension, or the heating wire cannot be firmly attached to the bottom of the spiral groove due to loosening, The winding length of the heating wire was not constant, and the resistance value of the heating wire varied. In addition, there is also a problem that molten plastic enters between the connector pin and the heating wire during the outer molding and causes poor contact. Furthermore, in extreme cases, the heating wire may be off. These phenomena are associated with a large fluctuation in tension in a winding step to be described later, and adversely affect each other. In addition, in the winding process, the addition of tension by the friction resistance method is affected by the inertia of a heating wire sending out bobbin and the like,
At the time of acceleration / deceleration, the fluctuation of the tension becomes large, and particularly at the time of startup, a tension exceeding the elastic limit of the heating wire itself is applied, and the heating wire elongates and local necking occurs, resulting in variation in the resistance value of the heating wire. Also, the change in load torque due to the change in electric heat dose wound on the bobbin also affected the tension. In recent years, instead of molding the inner having the above-described structure, for example, instead of the inner, only a connector pin fixing portion is injection-molded using a core metal, which is a kind of jig, and the heating wire bonded to the connector pin is connected to the core metal. Innerless joints manufactured by methods such as winding around the core and removing the core after forming the outer body have also come to be produced. It is a problem. Accordingly, it is an object of the present invention to provide a stable joint having a small variation in the resistance value of the heating wire and a method of manufacturing the joint and a winding device suitable for the manufacture.

[0006]

According to the present invention, there is provided an electric fusion plastic pipe joint formed by molding a heating wire having both ends joined to a connector pin with plastic. One end of the heating wire is welded to one of the two connector pins previously fixed to the molded body forming a part, and the heating wire is given a predetermined tension within the elastic limit and wound around the object to be wound. The end of the heating wire is welded to the connector pin by manufacturing by performing a process of welding and joining the other end of the heating wire in the working state to the other connector pin. Is characterized in that the tension is maintained, and the deviation of the resistance value of the heating wire from the specific resistance value is within 5% of the specific resistance value. Here, the specific resistance value is a resistance value measured when no tension is applied to the entire length of the heating wire required for the winding of the joint determined in advance. Further, the electrofusion-type plastic pipe joint of the present invention includes a plastic inner, a plastic outer provided so as to surround the inner, a heating wire wound around a spiral groove formed in the inner, and a heating wire. One end of the heating wire is welded to one of the two connector pins previously fixed to both ends of the inner, and a predetermined tension within the elastic limit is applied to the heating wire. The wire is wound around the spiral groove, and the other end of the heating wire under tension is contacted with the other connector pin and welded, so that the end of the heating wire is joined to the connector pin by welding The tension of the heating wire between the connector pins is maintained, and the deviation of the resistance value of the heating wire from the specific resistance value is within 5% of the specific resistance value. Also,
The electrofusion-type plastic pipe joint of the present invention includes a plastic inner, a plastic outer provided so as to surround the inner, a heating wire wound on a spiral groove formed in the inner, and both ends of the heating wire. One end of the heating wire is welded to one of the two connector pins previously fixed to both ends of the inner, and a predetermined tension within the elastic limit is applied to the heating wire. The wire is wound so as to be in close contact with the bottom of the spiral groove, and the other end of the heating wire in a state where tension is applied is brought into contact with the other connector pin to be welded and joined. The heating wire between the connector pins is maintained in tension, and the heating wire is wired closely to the bottom of the spiral groove. That is, the heating wire is welded firmly to one of the connector pins mounted on both ends of the inner in advance by welding, and then wound so as to be tightly attached to the bottom of the spiral groove by applying tension to the other connector pin as it is. Because it is strongly joined by welding,
The outer is formed in a state where the heating wire keeps the tension at the time of winding, and after the outer molding, the heating wire is maintained in a state of being closely attached to the bottom of the spiral groove and wired. Further, in the above-described electrofusion-type plastic pipe joint of the present invention, when the guide portion for guiding the heating wire is formed near the fixing portion of the connector pin, the heating wire is accurately aligned with the welding portion of the connector pin. This is desirable because resistance welding can be performed with high reliability. Therefore, the electrofusion-type plastic pipe joint of the present invention having the above-described configuration enables fusion-bonding to a plastic pipe in a constant energizing time.

[0007] The method of manufacturing an electro-fusion type plastic pipe joint according to the present invention includes an inner molding step of injection molding an inner, a pin attaching step of attaching a connector pin to a fixed seat provided on the inner, and a tip of the heating wire. A first joining step of joining the heating wire to one connector pin, a winding step of winding a heating wire around the spiral groove of the inner while applying tension, and a second joining step of joining the rear end of the heating wire to the other connector pin. And an outer molding step of injection-molding an outer on the outer periphery of the inner wire on which the heating wire is wound, comprising the steps of:
In the second joining step, the heating wire and the connector pin are resistance-welded, and in the winding step, tension is applied to the heating wire by a dancer roll provided at the tip of the pendulum to which the thrust has been given, and the dancer roll Is controlled by controlling the traveling speed of the heating wire so as to maintain the position of the heating wire at the initial setting position, thereby controlling the tension of the heating wire.

[0008] The winding device of the present invention comprises a wire feeder for supplying a heating wire by controlling the rotation speed of a bobbin around which the heating wire is wound, and a pendulum tension adjusting unit for applying a predetermined tension to the heating wire. While controlling the rotation speed and the axial moving speed by attaching the heating wire winding member, the heating wire having one end joined to the connector pin is spirally wound around the heating wire along the heating wire traveling path. A resistance welding machine is installed near the winding part to join the heating wire with the connector pin fixed to the heating wire winding member attached to the winding part.Each equipment is electrically connected to these equipment. And a control unit for controlling the Further, in the winding device of the present invention, in the above configuration, the wire supply unit has a servomotor connected to the bobbin to control the rotation speed, and the pendulum-type tension adjustment unit guides the heating wire to apply tension to the heating wire. A rotatable dancer roll to be added, a dancer arm with a dancer roll attached to the tip that performs a pendulum operation around a support shaft, and a low-friction drive air cylinder that is swingably connected to an intermediate portion of the dancer arm. And a sensor for detecting the swing angle of the dancer arm, and the winding part is connected to a holder on which the heating wire winding member is inserted to control the rotation speed, and to a connector pin. It is preferable to have a servomotor that controls the speed of the holder in the axial direction so that the joined heating wire is wound along the spiral groove of the heating wire winding member. The winding device of the present invention is suitable for an electric fusion-type plastic pipe joint, and is particularly intended for an inner part of an electric fusion-type plastic pipe joint as a heating wire winding member.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings, taking a joint having an inner member as an example. FIG. 1 is a perspective view showing the appearance of the joint 10 for each main manufacturing process. FIG.
(A) shows an inner molded body 1 made of polyethylene resin after the above-mentioned inner molding step, which has a spiral groove 2 on the outer peripheral surface and both ends for mounting connector pins 5 (5a, 5b). The fixed seats 4 (4a, 4b) are integrally formed by injection molding. FIG. 1B shows a state after the pin mounting step, in which a connector pin 5 made of, for example, a Cu-Zn alloy is preferably mounted and fixed to the fixed seat 4 using, for example, a robot. FIG. 1 (C) shows that after the first joining step in which the tip of the heating wire 3 made of, for example, a Cu-Ni alloy is resistance-welded to one connector pin 5a, the heating wire 3 is connected to the inner 1 while applying tension. The situation of the winding process in which the wire is wound so as to be in close contact with the bottom of the spiral groove 2 is shown. FIG. 1 (D)
After the winding, the rear end of the heating wire 3 is resistance-welded to the other connector pin 5b after a second joining step. After the above process, the inner 1 is mounted in an outer molding die, and an outer molding process is performed by injection molding the outer 6 with a polyethylene resin.
To get the finished product.

Next, the joining step, which is one of the technical points in the method of manufacturing the electro-fusion type plastic pipe joint of the present invention, will be described in detail by taking the first joining step as an example. The second bonding step is basically the same, and the description is omitted. As described above, the connection between the connector pin 5a and the heating wire 3 is performed by resistance welding. The outline is shown in FIG. 4. First, the connector pin 5a is brought into contact with the end face of one electrode 15b of the resistance welding machine. Next, the heating wire 3 is brought into contact with the connector pin 5a, and the heating wire 3 is pressed by the other electrode 15a of the resistance welding machine. Next, when a welding current is applied through the electrode 15, the temperature rise between the connector pin 5 a having the smallest contact area and the largest resistance value and the heating wire 3 becomes the highest, and the contact portions of the two melt locally and the alloy layer is melted. Is made and the joint is made. Since the temperature between the electrode 15b and the connector pin 5a and the temperature between the heating wire 3 and the electrode 15a do not rise to a temperature at which they are melted, there is no welding or deformation. Note that, as described above, the electrode 15
Is configured to be able to move and pressurize, and to allow a large current to flow with one as the positive electrode and the other as the negative electrode.The material can be, for example, chromium copper, tungsten, molybdenum, etc. I do. The quality of resistance welding is determined mainly by the conditions of current, pressure, and time, but these are also affected by the material and contact area of the electrode and the workpiece. Is desirable.

FIG. 5A is a sectional view showing a state in which the connector pin 5 is mounted on the fixed seat 4.
Can be divided into a connection part 51 for connecting a terminal on the controller side, a welding part 52 for joining a heating wire, and an insertion part 53 to be inserted into and fixed to the fixed seat 4. The welding portion 52 is a portion where a heating wire is wound a plurality of times by forming a conventional brim or the like, but can be formed in a simple columnar shape as shown in FIG. 5B. Further, as shown in FIG. 5 (c), a concave groove for positioning the heating wire may be formed, or a prism may be formed. The dimension corresponding to the diameter is not particularly limited, but may be larger than the insertion portion 53 so that the insertion depth into the fixed seat 4 is easily made constant.

In the inner molding step, as shown in FIG. 6, the heating wire 3 is brought into contact with or near the fixed seat 4.
By forming a rib-shaped or block-shaped guide portion 8 that acts as a guide or support when connecting the heating wire 3 to the connector pin, the heating wire 3 can be accurately aligned with the welding portion 52. In addition, it is possible to prevent joint failure due to poor positioning of the two members during resistance welding and to prevent the occurrence of a short stop in equipment. In particular, in the second joining step after the completion of the winding, the heating wire 3 that conventionally rises from the spiral groove 2 is connected to the welding portion 52.
Although it is difficult to accurately adjust the position, it is effective because the guide portion 8 can easily adjust the position. Therefore, it is not always necessary to provide the fixing seats 4a and 4b at both ends, but may be installed only on the target fixing seat 4b side in the second joining step. It is more preferable that the guide portion 8 is formed integrally with the fixed seat 4 so as to have a shape which acts to improve the rigidity of the fixed seat. In this case, the connector pin 5 is prevented from falling down against thrust force acting on the connector pin 5 acting during resistance welding and winding, and the die and the connector pin 5 in the outer molding process are formed.
It is possible to prevent the connector pin 5 from being crushed or caught or to be crushed when the mold is clamped, which is effective for improving the product yield and the production cycle.

Next, the winding step, which is another technical point of the steps of the method for manufacturing the electro-fusion type plastic pipe joint of the present invention, will be described in detail below. In this winding step, tension is applied to the heating wire by a pendulum type tension control system shown in FIG. The pendulum-type tension control system controls the rotation speed of the bobbin 22 around which the heating wire is wound, and supplies the heating wire 3 to the wire rod supply unit 20;
Pendulum type tension adjusting unit 30 for applying a predetermined tension to heating wire 3
And a winding part 40 for attaching the inner 1 to control the rotation speed and the axial movement speed, and winding the heating wire 3 around the spiral groove, and a control part 45 electrically connected to these parts to control each part.
(Not shown). The wire rod supply unit 20 includes the bobbin 2
2 and a servomotor 21 for controlling the rotation speed. The pendulum-type tension adjusting unit 30 is a rotatable dancer roll 3 that guides the heating wire 3 and applies tension to the heating wire 3.
2, a dancer arm 33 which is swingable about a support shaft 36 and has a dancer roll 32 attached to the end thereof, and a support shaft 37
An actuator, such as an air cylinder 34, which is swingably connected to an intermediate portion of the dancer arm 33 and outputs a precise force, and a sensor 35 which detects the swing angle of the dancer arm 33, are provided. It is installed in the middle of the traveling route of the heating wire 3 at the time. The winding part 40 includes a servomotor 41 connected to a holder into which the inner 1 is inserted and controlling the rotation speed, and a heating wire 3 connected to the connector pin 5.
Has a servomotor (not shown) that controls the speed of the holder in the axial direction so that the holder is wound along the spiral groove 2 of the inner 1. The pendulum-type tension control system includes a guide roll 31 for guiding the heating wire 3 traveling,
A tension measuring device 39 for measuring the tension of the heating wire 3 during traveling is appropriately disposed at a predetermined position.

Next, a method of applying tension to the heating wire 3 in the pendulum type tension adjusting section 30 will be described. The application of tension to the heating wire 3 is performed through a dancer roll 32 by supplying a predetermined air pressure to the air cylinder 34, giving a thrust F of the air cylinder 34 driven by the air pressure to the dancer arm 33. The tension T applied by the thrust F of the air cylinder 34 is a length L1 from the swing center of the dancer arm 33 to the connection with the air cylinder 34, and the rotation center of the dancer roll 32 from the swing center of the dancer arm 33. The following equation can be calculated from the length L2, the pressure receiving area A1 and the air pressure P1 of the supply side piston of the air cylinder 34, the air pressure P1, the pressure receiving area A2 and the air pressure P2 of the exhaust side piston, and the internal frictional resistance K of the piston and the like. T = 1/2 × L1 / L2 × F Here, F = A1P1-A2P2-K Therefore, it is important to accurately and stably maintain the thrust F of the air cylinder 34, and therefore, the air pressure on the air supply side is required. P1 can be set and maintained with high sensitivity and high accuracy, and the exhaust side air pressure P2 and the internal frictional resistance K are minimized so as to be almost negligible.

The supply air pressure P1 can be set with a sensitivity of 0.01 kg / cm ² by using a precision regulator. As this precision regulator, it is desirable to use an electropneumatic conversion regulator that can set the air pressure steplessly and with high precision according to an external voltage or current input and that performs constant value control by feedback. In this case, regardless of whether the heating wire 3 is running or stopped, the supply air pressure P1 of the air cylinder 34 can be controlled by a command from the control unit 45, and the tension value applied to the heating wire can be arbitrarily and precisely determined. Can be controlled remotely. The exhaust side of the air cylinder 34 is short and thick so that the pressure loss is reduced so as to be completely open to the atmosphere, so that no residual pressure remains. Regarding frictional resistance K, instead of sliding solid packing for the seal between the piston and cylinder, use a diaphragm made of a thin film molded product of rubber and cloth, and use a linear ball bearing for the rod bearing. The miniaturization is achieved by using a bellofram cylinder. Therefore, this cylinder can respond sensitively to minute displacement. It is also important that the thrust F of the air cylinder 34 be transmitted to the dancer roll 32 without being consumed by friction or the like on the way. A bearing having a low friction coefficient is attached to the support portion, and the weight of the moving portion is reduced. It is trying to make it. That is, a ball bearing is installed on the support shaft 36 of the dancer arm 33, a ball bearing is installed on the support shaft 37 of the air cylinder 34, and the dancer arm 33 and the air cylinder 34 are connected by a ball joint. Furthermore, the material of the dancer arm is aluminum, and the material of the dancer roll is lightweight and wear-resistant engineering plastic. The weight reduction of this moving part is initially set when the dancer arm swings 33, the weight calculated by the angle component is newly added as tension, and the thrust of the air cylinder 34 of the heating wire 3 is applied. From the viewpoint of varying the tension T, it is also effective in reducing the tension.

Next, a tension control method will be described. The basis of this control method is to control the speed of the servo motors 41 and 21 so that the speed of the heating wire wound around the spiral groove 2 of the inner 1 is the same as the speed of the heating wire sent out from the bobbin. The dancer arm 33 to which a predetermined tension T is applied by the cylinder 34 is kept at the initially set position. The reason why the speed of winding and feeding the heating wire 43 is controlled so that the dancer arm 33 is always at the initial setting position is that when a speed difference occurs between the winding and feeding of the heating wire 43, the rod of the air cylinder 34 is moved. This is absorbed by the dancer arm 33 swinging to the left and right while being displaced, but the tension T at this time should not change because the thrust F of the cylinder 34 is kept constant. This is because, when the arm swings, the weight calculated by the angle component is added to the tension to cause a tension fluctuation. By this, the winding with reduced tension variation is accelerated even at the time of acceleration of the winding start, at the time of deceleration before the end, and even at the speed change of the heating wire which leads to the slight change of the spiral groove diameter at the time of constant speed rotation. can do. More specifically, with reference to FIG. 7, when the feeding is slower than the winding of the heating wire 3, the dancer arm 33 swings rightward from the initially set vertical state. The control unit 45 outputs a signal from the sensor 35 that detects the deflection angle of the dancer arm 33, speed data of the winding-side heating wire obtained based on the rotation speed information of the winding-side servomotor 41 and the spiral groove diameter,
Based on the heating wire winding diameter data of the heating wire delivery bobbin,
A speed control command is output to the servo motor 21 on the heating wire sending side so that the dancer arm 33 returns to the initial setting position.

In practice, the first joining step, the winding step, and the second joining step described above can perform a series of processes.
It can be put together as one winding device. That is, the basic configuration of the winding device is based on the pendulum-type tension control system described above, and a resistance welding machine is disposed near the winding portion 40. The servo motor 41 for controlling the rotation of the holder of the winding part 40 and the servo motor for moving in the axial direction are controlled so that the connector pin 5 attached to the inner 1 is at a predetermined position for connection with the heating wire. The position is controlled by 45. As a peripheral device, means for cutting the heating wire after winding, means for holding this heating wire and leading it to a new connector pin position at the next winding, for example, a pinch roller is provided at the end of the heating wire traveling path. Provide near. Further, the current value and the pressing force at the time of resistance welding can be easily measured by a known technique, and the tension at the time of winding can be measured by the tension measuring device 39. Therefore, the control unit 45 monitors these values and sets them. When the value is out of the allowable range, the winding device can be stopped to notify the abnormality. As described above, by manufacturing a joint using this winding device, productivity can be improved and quality can be stabilized. In addition, in addition to the above-described configuration, the present winding device can be built up as required, such as installing a connector pin mounting means or installing an inner handling device. Further, the present invention can be applied not only to winding of a heating wire to a joint, but also to winding of a cylinder having a similar connector pin. As described above, the description has been given of the example in which the joint having the inner is targeted. However, also for the innerless joint, regarding the joining step and the winding step, which are the points of the present invention, the winding target is not the inner but the core metal as described above. It is needless to say that the present invention can be applied except for the above.

[0018]

EXAMPLE A union polyethylene resin electrofusion type pipe joint having a nominal size of 100 and a heating wire diameter of 1.1 mm was manufactured by the manufacturing method of the present invention. In the production, the first joining step, the winding step, and the second joining step were performed by the above-described winding device, but the other steps were the same as the conventional processing. The heating wire material and the connector material were the same as those described above, and the welded portion 52 of the connector pin 5 was a simple columnar shape. The breaking strength of a heating wire having a wire diameter of 1.1 mm is 30 kgf, the elastic limit is 10 kgf, and the welding strength, welding force,
Welding conditions such as welding time were set. It was experimentally confirmed that the bonding strength under this condition was stable at 20 to 25 kgf. The winding conditions were set at a tension of 8 kgf and a winding speed of 25 m / min.

FIG. 8 shows an example in which the tension in the winding is measured by a tension measuring device using the winding apparatus of the present invention. As a comparative example, the state of fluctuation in tension during winding in a conventional manufacturing method is also shown. The vertical axis shows the tension value, and the horizontal axis shows the elapsed time from the start to the end of the winding. As shown in FIG. 8, the tension fluctuation of the conventional frictional resistance type is large, and particularly at the time of startup, exceeds the elastic limit of 10 mmf of the φ1.1 mm heating wire, and the fluctuation is large. On the other hand, the tension of the tension control performed by this winding device is
From the beginning to the end of the winding, it is 8 ± 0.4 kgf, which indicates that the winding is accurate and stable.

Thereafter, 250 joints were extracted from the joint of the present invention, which was made into a final product through an outer molding step, and joints manufactured by the conventional manufacturing method under the same conditions, and their resistance values were measured and compared. FIG. 9 shows the result. The vertical axis shows the distribution frequency, and the horizontal axis shows the resistance value. The resistance value was measured through both connector pins. The resistance value of the connector pin was minimal compared to the heating wire, and this value can be evaluated as representing the resistance value of the entire heating wire. As described above, the resistance value of the heating wire affects the fusion performance of pipes and joints and affects the quality of the product. Value is close to the specific resistance value (0.66Ω here)
It is better that there is no variation.

When the resistance value of the joint of the present invention is statistically observed,
The average value is 0.668Ω, the standard deviation σ is 0.004Ω, and the variation evaluated at 6σ is 0.024Ω, so the maximum value is 0.68Ω.
Can be calculated. On the other hand, when the joints of the conventional manufacturing method were similarly calculated, the average value was 0.691Ω and the standard deviation σ was 0.006.
Ω, and the variation evaluated at 6σ is 0.036Ω, so the maximum value can be calculated as 0.709Ω. When the maximum deviation of the resistance value from the specific resistance value is calculated from this, the joint of the present invention is 0.02 (= 0.68−0.66) Ω, which is about 3% of the specific resistance value of 0.66Ω. Is 0.049 (= 0.709-0.
66) about 7% of the specific resistance value of 0.66Ω, which is about twice as large as the maximum displacement of the joint of the present invention. In particular, the difference in the average value is large because the heating wire is plastically deformed and constricted because a tension exceeding the elastic limit of the heating wire acts at the initial stage of the winding as shown in FIG. Seem. From this, the joint manufactured by the manufacturing method of the present invention has an average resistance value closer to the inherent resistance value of the heating wire than the conventional one,
The deviation of the resistance value from the specific resistance value is at least within the range of 5% of the specific resistance value, and it can be said that the fusion performance is stable.

[0022]

The electric fusion type plastic joint of the present invention has the following effects. 1) The resistance value of the heating wire is almost the same as the predetermined value and has little variation, so that the fusion bonding with the pipe can be performed by energizing for a certain period of time. 2) Since the connection between the connector pin and the heating wire is strong and there is almost no failure due to poor connection, the production yield is high and defective products are not shipped. 3) When a guide portion for supporting the heating wire is provided in the vicinity of the fixing seat of the inner member, when the connector pin and the heating wire are joined, the heating wire can be accurately positioned on the connector pin and reliable resistance welding can be performed. Further, the method for producing an electro-fusion type plastic joint of the present invention has the following effects. 1) Even if there is a change in the number of revolutions of the heating wire winding member at the beginning and end of the winding or a change in the speed of the heating wire at the time of winding, the winding can be performed with little variation with respect to the set tension. 2) The connection between the connector pin and the heating wire is strong, the heating wire can be wound along the inner spiral groove with a predetermined tension, and the displacement and extension of the heating wire can be prevented. 3) Since the connector pin and the heating wire are firmly joined and can be wound with little variation with respect to the set tension, it is possible to manufacture a product with little variation in resistance of the heating wire. 4) The connection between the connector pin and the heating wire is strong, and the heating wire does not come off from the connector pin, and the resin does not enter between the connector pin and the heating wire during outer molding. High product can be manufactured. The winding device of the present invention has the following effects. 1) Since the joining process of the connector pin and the heating wire and the winding process of the heating wire can be performed by one device, the productivity can be improved. 2) Since the joining condition between the connector pin and the heating wire and the tension of the heating wire can be monitored in-line, a joint having stable quality can be obtained.

[Brief description of the drawings]

FIG. 1 is an external view of a main manufacturing process of an electrofusion-type plastic joint of the present invention.

FIG. 2 is a diagram showing a connection state between an electrofusion-type plastic joint and a pipe.

FIG. 3 is a diagram showing connection between a heating wire and a connector pin by conventional caulking.

FIG. 4 is a diagram showing an outline of resistance welding between a connector pin and a heating wire;

FIG. 5 is a view showing the shape of a connector pin.

FIG. 6 is a view showing a guide portion for guiding and positioning a heating wire to a connector pin;

FIG. 7 is a diagram showing an outline of a pendulum type tension control system.

FIG. 8 is a diagram comparing tension states when the winding device of the present invention is wound with a conventional frictional resistance type.

FIG. 9 is a diagram comparing resistance values of a heating wire of the joint of the present invention and a conventional joint.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Inner, 2 ... Spiral groove, 3 ... Heating wire, 4 ... Fixed seat, 5 ... Connector pin, 6 ... Outer, 8 ... Guide part, 10 ... Electric fusion plastic joint, 15 ... Electrode, 20 ... Wire rod supply part , 21 ... servo motor, 22
... bobbin, 30: pendulum-type tension adjuster, 32: dancer roll, 33: dancer arm, 34: air cylinder, 35: swing angle detection sensor, 36: support shaft, 3
9: tension measuring device, 40: winding part, 41: servo motor

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kiyoshi Ikeda 2 Daifuku, Kuwana-shi, Mie Examiner, Hitachi Metals Co., Ltd. Kuwana Plant Takatoshi Ikeda (56) References JP-A-4-59319 (JP, A) Hei 10-26284 (JP, A) JP-A-9-164597 (JP, A) JP-A 7-144832 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16L 47 / 02

Claims (9)

(57) [Claims] 1. An electric fusion plastic pipe joint formed by molding a heating wire joined at both ends to a connector pin with plastic, wherein both connector pins previously fixed to a molded body forming a part of the joint are provided. One end of the heating wire is welded to one end, a predetermined tension within the elastic limit is applied to the heating wire and the wire is wound, and the other end of the heating wire under tension is brought into contact with the other connector pin and welded. The ends of the heating wire are joined to the connector pins by welding. The heating wire between the connector pins is maintained in tension, and the deviation of the resistance of the heating wire from the specific resistance is within 5% of the specific resistance. An electrofusion-type plastic pipe joint characterized by the following. 2. A plastic inner, and a plastic outer provided so as to surround the inner,
It consists of a heating wire wound on a spiral groove formed in the inner, and metal connector pins connected individually to both ends of the heating wire, and a heating wire is connected to one of both connector pins fixed in advance to both ends of the inner. One end of the heating wire is given a predetermined tension within the elastic limit to the heating wire, wound around a spiral groove, and the other end of the heating wire in a state where the tension is applied is in contact with the other connector pin and welded, The ends of the heating wire are welded to the connector pins. The tension between the heating wires between the connector pins is maintained, and the deviation of the resistance value of the heating wire from the specific resistance value is within 5% of the specific resistance value. An electrofusion-type plastic pipe joint characterized by the above-mentioned. 3. A plastic inner, and a plastic outer provided so as to surround the inner,
It consists of a heating wire wound on a spiral groove formed in the inner, and metal connector pins connected individually to both ends of the heating wire, and a heating wire is connected to one of both connector pins fixed in advance to both ends of the inner. One end of the heating wire is welded to give a predetermined tension within the elastic limit to the heating wire so as to be in close contact with the bottom of the spiral groove, and the other end of the heating wire under tension is in contact with the other connector pin. By welding, the ends of the heating wires are joined to the connector pins by welding, the heating wires between the connector pins are maintained in tension, and the heating wires are wired closely to the spiral groove bottom. Characterized by electrofusion plastic pipe fittings. 4. The electro-fusing plastic pipe joint according to claim 1, wherein a heating wire guide portion is formed near the fixing portion of the connector pin. 5. An electrofusion-type plastic pipe joint as claimed in claim 1, wherein said joint can be fusion-bonded to a plastic pipe for a predetermined energizing time. 6. An inner molding step of injection molding an inner, a pin attaching step of attaching a connector pin to a fixed seat provided on the inner, and a first joining step of joining a tip of a heating wire to one of the connector pins. A winding step of winding a heating wire around a spiral groove of the inner while applying tension, a second joining step of joining a rear end of the heating wire to the other connector pin, and an inner wire wound with the heating wire. An outer molding step of injection-molding an outer on an outer periphery of the plastic pipe joint, wherein in the first and second joining steps, the heating wire and the connector pin are resistance-welded, and the wire is wound. In the process, a tension is applied to the heating wire by a dancer roll provided at the tip of the pendulum to which the thrust has been applied, and the heating wire is applied so that the dancer roll is maintained at the initial setting position. Electrical welding type method for producing a plastic pipe joint is characterized in that by controlling the line speed to control the tension of the heating wire. 7. A wire feeder for supplying a heating wire by controlling a rotation speed of a bobbin around which the heating wire is wound, a pendulum-type tension adjusting unit for applying a predetermined tension to the heating wire, and a heating wire winding member And a winding part for spirally winding a heating wire having one end joined to the connector pin while controlling the rotation speed and the axial movement speed, and sequentially disposing the heating wire along the heating wire traveling path, A resistance welding machine that connects the connector pin fixed to the heating wire winding member attached to the winding part and the heating wire near the unit is installed, and a control unit that is electrically connected to each of these facilities and controls each facility. A winding device comprising: 8. The winding device, wherein the wire feeder has a servomotor connected to the bobbin to control the rotation speed, and the pendulum tension adjuster guides the heating wire to apply tension to the heating wire. A dancer arm that can move freely, a dancer arm with a dancer roll attached to the tip that performs a pendulum operation around a support shaft, a low-friction drive air cylinder that is swingably connected to an intermediate portion of the dancer arm, and a dancer arm The winding portion is connected to a servomotor that controls the rotation speed by connecting to a holder into which the heating wire winding member is inserted, and is connected to a connector pin. The winding device according to claim 7, further comprising a servomotor that speed-controls the holder in the axial direction so that the heating wire is wound along the spiral groove of the heating wire winding member. 9. The winding device according to claim 7, wherein the heating wire winding member is an inner part of an electric fusion type plastic pipe joint.