JPH02231127A - Method and apparatus for fusion of electrofusion joint - Google Patents

Abstract

PURPOSE:To make it possible to keep the temp. of a fusing interface in the optimum temp. range for a long time by dividing the whole time energized to a joint into several divisions and setting an electric voltage and an electric current so as to decrease stepwisely. CONSTITUTION:An initial electric voltage is set at e.g. 40V by mens of an electric voltage controlling device 36 and a connector 7 is inserted into an inserting hole 2. A start button 18 is pushed and a switching device 37 is closed. An electric current is energized in an electric heating wire 3 under the initial electric voltage of 40V and the surrounding resin is melted. A molten resin flows into a hole 4 for detection and pushes up a slide block 16 to actuate a micro-switch 13. An output signal is input to CPU31 and an electric voltage controlling device 36 is switched to e.g. 15-30V based on a data from ROM33. At the same time, the time from the starting time of energizing to the switching is measured by means of CPU31 and an energizing time of the last period is calculated by multiplying this time by a specified factor. A timer 34 measures time and heat-melting is performed under the last half electric voltage. The timer 34 is time-up and energizing is stopped. When the connector 7 is taken off, the resin which has flown in a small hole 14 is solidified and a projection 19 is projectedly formed and the completion of fusion is confirmed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for fusing an electrofusing joint that is used to connect plastic pipes and has heating wires embedded in the contact surface with the pipes. ．． Conventional technology Electrophasic fittings have been developed in recent years as fittings for plastic pipes used in water, sewage and gas pipes. There are various types of fittings, such as pipe fittings, T-fittings, saddle fittings, and cap fittings, but electrofusion fittings are all made of molded products with heating wires embedded in the contact surface with the pipe. Fusing with the pipe is done by fitting the joint into the end of the pipe or by pressing it against the outer circumferential surface of the pipe from the side and applying electricity to heat and melt the contact surface. The amount of power applied to these fittings affects the quality of the plastic pipe connections; too much power can cause overheating and deformation of the fittings and pipes, while too little power may cause insufficient heating. As a result, the strength of fusion decreases. The device that energizes the fittings has traditionally been operated manually;
The amount of electricity to be energized used to be determined by the worker on site, based on the appearance of the joint during welding, but in recent years it has been decided in advance based on the size and type of the joint. A method has begun to be adopted in which the amount of electricity is set in advance, and the operator identifies the type of joint based on its appearance and determines the corresponding amount of electricity. Recently, regarding pipe joints,
Depending on the type of joint, a resistor with a different resistance value is embedded separately from the heating wire, and the resistance value is detected by passing a test current through the pipe joint, or the resistance value of the heating wire itself is detected. A method of identifying the type of the joint and applying the corresponding amount of power, and a method of determining the energization time by reading the pattern of the coding tab provided integrally with the joint (Japanese Patent Laid-Open No. 1983-
175022), a method has been proposed in which a hole is provided that reaches from the outer surface of the joint to the vicinity of the heating wire, and the molten resin flowing out from the bottom of the hole is detected by a position detection switch to cut off the electricity. The problem to be solved by the invention All conventional methods are ii! ! The heating method is carried out at a constant voltage with a constant voltage or a constant current with a constant current for a set time, and the temperature of the heating wire and the temperature of the fusion interface are as shown in Figure 7. , continues to rise until the energization is stopped, at which point it reaches its maximum value,
After stopping, it drops rapidly. In electrophasic joints, in order to ensure the required fusion performance, the temperature of the heating wire must not rise to the temperature at which the resin deteriorates, and the temperature at the fusion interface must be as high as possible without deteriorating the resin. , and be able to hold it for a long time, etc., and the maximum temperature is set as high as possible and the resin is Although it is set so as not to exceed the upper limit temperature at which deterioration occurs, the maximum temperature is determined by the environmental temperature, the gap between the inner diameter of the joint and the outer diameter of the pipe, the dimensional tolerance of the joint and pipe, even if the voltage or current and energization time are constant. The resistance value of the heating wire fluctuates up and down due to the tolerance etc., and when the amount of fluctuation becomes large, the heating wire may rise above the upper limit of the deterioration temperature of the resin, or conversely, the temperature at the fusion interface may rise, as shown by the broken line in the figure. If the temperature falls below the minimum temperature required for fusion, sufficient fusion performance may not be obtained. The same is true if the actual energization time deviates from the optimal energization time for fusion. In addition, in a method that has a hole that reaches from the outer surface of the joint to the vicinity of the heating wire, and the molten resin flowing out from the bottom of the hole is detected by a position detection switch or a pressure sensor to cut off the current, the distance between the bottom of the hole and the heating wire is The energization time also changes depending on the dimensional tolerance of the heating wire and the temperature of the fusion interface. Moreover, this method has the advantage that unfinished fusion can be confirmed by looking at the solidified bead of molten resin that has flowed into the hole, but this bead is usually detected midway through the hole by a position detection switch or pressure sensor. Since the outflow has been stopped, it is very difficult to see from the outside, and unless you look carefully, you will not be able to confirm whether or not the fusion has been completed. The purpose of the present invention is to make it possible to maintain the temperature of the fused interface higher than conventional ones and for a longer period of time without exceeding the deterioration temperature of the resin. Another object of the present invention is to make it easy to confirm whether or not fusion has been completed. One way to achieve the goal of maintaining the temperature of the fused interface within the optimal temperature range for a long time is to lower the voltage or current in stages. In other words, one invention is an electrofusicon in which a heating wire is buried in the contact surface with a plastic tube, and the fusion with the tube is performed by applying a predetermined amount of electric power to the heating wire to heat and melt the contact surface. This joint fusion method is characterized in that the entire energization time for the joint is divided into several sections, and the voltage or current is set to decrease in stages.

One way to lower the voltage or current stepwise is to use a pressure sensor to detect the pressure increase due to thermal expansion of the molten resin during welding, and then reduce the voltage or current to a predetermined level when the pressure reaches a preset pressure. The method of switching is to create a detection hole that reaches near the heating wire from the outer surface of the joint, insert a position detection switch into the hole, and press up the position by the inflow of molten resin from the bottom of the hole caused by the pressure increase during fusion. A method of activating a limit switch, multi-contact, or variable resistor with a detection switch and switching the voltage or current using the output signal, and setting the energization time division and the voltage or current in each division in advance according to the type of joint. In addition, there is a method in which an identification means is installed on the joint to display the type, and the identification means is read by a sensor and switched to a predetermined voltage or current at a predetermined time based on the data obtained. Among the above methods, when using a pressure sensor, the current or voltage may be directly switched when a predetermined pressure is reached, or the pressure sensor may be used to operate a multi-contact or variable resistor, for example. This may allow the voltage or current to be switched. In the method of providing an identification means, the identification means includes, for example,
Depth of the hole formed in the outlet, outer diameter of the outlet, inner diameter of the hole, wall thickness, height of the outlet, recording temporarily formed with the outlet or joint, unevenness or hole, magnetic tape , barcodes, etc. Sensors include a position i sensor that reads the amount of displacement when a connector hits the contact surface when it is connected, and a sensor that emits light or sound waves and reads the time until it hits the contact surface and bounces back. , an optical sensor consisting of a light emitting part and a light receiving part, a magnetic sensor, a limit switch, etc. can be exemplified. Switching of voltage or current is performed when the pressure reaches a preset pressure, when a limit switch, multi-contact, or variable resistor is activated, or it is preset according to the type of joint. In the latter case, and even in the former two cases, the time until the energization is stopped after switching is usually
It is determined by multiplying the first divided time or the time before switching by a predetermined coefficient, and when the energization time is divided into two, the latter half is set in the range of 173 to 1/1 times the earlier time. may be calculated based on a predetermined formula. In this case, the voltage or current at the latter stage is set to 173 to 374 times the voltage or current described above. Another invention that achieves the above object is to embed a heating wire in the contact surface with the plastic tube, and the fusion with the tube is performed by applying a predetermined amount of electric power to the heating wire to heat and melt the contact surface. In the method for fusing electrofusion joints,
This system is characterized by dividing the total energization time into the joint into two periods: the first and second periods, and the voltage or current is continuously lowered during the second period. Switching between voltage and current is performed in the same manner as above. Yet another invention that achieves the above object is to set a relational expression between electric power and energization time such that the electric power gradually decreases as the energization time elapses, and to control the electric power according to this expression. be. That is, in a method of fusing an electrofusion joint, a heating wire is buried in the contact surface with the plastic pipe, and the welding with the pipe is performed by applying a predetermined amount of electric power to a 28 wA electric current to heat and melt the contact surface. A relational expression between power and energization time is set such that the power gradually decreases as the energization time passes, and the voltage and/or current is controlled so that the power value gradually decreases in accordance with the above relational expression during energization. It is characterized by this. The device for gradually decreasing the power according to the set relationship 2 includes a current measuring means, a voltage measuring means, a regulating means for adjusting the current and/or voltage, and a voltage and current measured from both measuring means. Calculate the power, and when the power value calculated based on the relational expression between the preset energization time and the power that gradually decreases over time is exceeded, the voltage and/or current is lowered, and when it falls below the above power value, the voltage and/or current is and a control means for controlling the adjustment means so as to increase the amount of the adjustment means. For example, if the initial value is 1, the degree of change in the supplied power is set to about 0.3 to 0.6 at the final time of energization, and even if the relation between power and energization time during this period is a linear function, It may be a quadratic or multidimensional function. In any case, the temperature of the heating wire when electricity is stopped is the deterioration temperature of the resin (usually about 3
(approximately 50℃) or below. The above relational expressions are also set individually depending on the type and size of the joint, and the type of joint is identified and the corresponding relational expression is found from a list, and the power supply conditions are set manually or as described above. Similar to the above method, this is done automatically by using a sensor to detect the identification means provided on the joint. That is, a sensor is connected to the control means for reading data regarding the type of the joint from an identification means provided on the joint, and a memory means storing the relationship between power and energization time corresponding to the type of joint, a timer, and a CPU are connected to the control means. established,
The CPU reads out the relational expression corresponding to the data input from the sensor from the storage means, calculates the power manually from the clock generation means, and compares and checks this with the power calculated from the measured voltage and current. Control means for regulating voltage and/or current. Unfinished fusion! ! The invention for making the identification easier is to embed a heating wire in the contact surface with the plastic tube, and to fuse it with the tube, apply a predetermined amount of electric power to the heating wire to heat and melt the contact surface. In the fusion fFW process of electrofused joints carried out by A position detection switch or pressure switch that is moved and detects the molten resin is provided, and the position detection switch or pressure sensor includes:
Small holes are formed on the bottom surface that comes into contact with the molten resin. Here, the small hole usually has an inner diameter of 1 to 3 mm and a depth of 1 to 20 m.
Preferably, an air vent is formed deep therein so that the molten resin can easily flow in. Although the detection hole may be provided at a location different from the socket into which the connector is inserted, it is preferably formed at the socket, and more preferably formed at each of the pair of sockets. It is desirable to provide positioning means for connectors that are inserted into sockets to ensure proper connection. The positioning means is, for example, a terminal that protrudes from the inner periphery of the connector, and when it comes into contact with the insertion port during connection, conduction is established, and whether or not the connection has been properly performed is determined by the presence or absence of conduction. In this case, it is more desirable to install a CRT to display continuity so that the operator can easily know the connection, or to install an indicator light or buzzer to indicate continuity. For position detection switches or pressure sensors, it is desirable to form fluorocarbon resin on the parts that come into contact with the molten resin, or to treat them with fluorocarbon treatment. This prevents molten resin from adhering to the position detection switch or pressure cassette. This makes it easier to remove the sensor. Note that the present invention may be implemented alone or in combination with the methods described above. Furthermore, the invention described above is applicable not only to pipe joints but also to saddle joints, T-joints, cap joints, etc. Effect Figure 6 shows an example in which the energization time is divided into two sections, the above and the latter half, and the latter voltage is set lower than the above voltage. The voltage rises in the same way as the voltage, and when the temperature approaches the upper limit temperature at which resin deterioration begins, the voltage is switched to a lower voltage in the later stages. When the voltage decreases, the temperature of the heating wire almost stops rising. However, although the temperature at the fusion interface slows down due to switching, it still rises as it approaches the temperature of the heating wire. Then, when the electricity is turned off and the temperature of the heating wire drops, it begins to drop (see Figure 7). As described above, even if the maximum temperature of the heating wire is lowered than before, it is possible to maintain the temperature of the fusion interface above the minimum temperature for a long time, and it is possible to prevent changes in environmental temperature and the gap between the inside diameter of the joint and the outside diameter of the pipe. Even if there are variations in the heating wire and interface temperature due to differences, dimensional tolerances of joints and pipes, resistance tolerances of electric wires, etc., and even if the actual energization time may deviate slightly from the optimal energization time, It is possible to maintain the interface temperature within the normal temperature range. The same effect as above will occur if the energization time is divided into the first and second periods, and the temperature of the heating wire is raised to near the upper limit temperature in the first period, and then the voltage is continuously lowered in the second period. ．． When the power supply is gradually decreased as the energization time passes, as shown in Figure 13, the temperature of the heating wire, which rose rapidly at the beginning due to the gradual decrease in the power supply, gradually slows down as time passes. It starts to drop after the power supply is stopped. Similar to the above method, compared to the conventional method, the temperature rise is more gradual, allowing the temperature to remain in the optimum range for a longer period of time. If a small hole is formed in the bottom of the position detection switch or pressure sensor in a device that can confirm whether or not fusion has been completed, molten resin may flow out from the bottom of the hole due to the increase in pressure due to thermal expansion during fusion. The molten resin lifts the position detection switch or pressure sensor, and a portion of the molten resin flows out into the small hole. When the connector is removed after fusion,
The resin that flows into the small hole and solidifies becomes a pin-shaped protrusion, making it relatively easy to confirm from the outside. Embodiment Fig. 1 shows a pipe joint, in which the joint l has insertion ports 2 protruding from both the left and right sides, and each insertion port 2 is formed with a detection hole 4 that reaches from the surface to the vicinity of the S heating wire 3. An annular terminal 5 connected to a heating wire 3 is integrally provided on the outer periphery of the insertion port 2. A connector 7 that is removably connected to the insertion port 2 is provided with a cap-shaped connector main body 8 and on the lower inner circumference of the zero body 8, and contacts the terminal 5 when connected, and has a voltage and energization time. A terminal l1 is connected to the control device 9 via a conductive wire A, a positioning terminal l2 is connected to the control device 9 via yA & ilB and contacts the upper end surface of the terminal 5 during connection, and the main body 8, and the control device 9
and microswitch l3 connected via conductors C and D.
It is connected to a microswitch 13 and inserted into the detection hole 4 when connected, and has a blind hole-like elongated small hole 14 formed from the bottom and an air vent 15 at the upper end of the small hole. It consists of a slide block l6. As shown in FIG.
The basic configuration includes a PU 31, a ROM 32, and a RAM 33, a timer 34, a voltage adjustment means 36, a switch means 37, and a clock generation circuit (not shown), and includes a terminal 11, a positioning terminal 12, and a microswitch 13.
are connected to the CPU 31. The ROM 32 stores a program for fusion, and the RAM 33 stores various data for fusion. C P U31
calculates the time from the start of energization to the time of switching, multiplies this by a coefficient read from the RAM 33 at the time of switching to calculate the latter energization time, and sets it in the timer 34.

The timer 34 starts timing by the output signal from the CPU 31 when switching the voltage, and outputs the output to the switch means 37 after the latter energization time has elapsed to stop the energization. The start of energization is performed by pressing the start button 18.

FIG. 3 shows the functions of the control device configured as described above. When the connector 7 is inserted into the insertion port 2, the positioning terminal 12 comes into contact with the terminal 5, and the conductors A and B are electrically connected. The connection is confirmed by . When inserting the connector 7, it should be displayed on the CRT (not shown) so that the operator can easily confirm that the insertion has been completed and the conductors A and B have become conductive. The information will be displayed using an indicator light or a buzzer. Before and after the connector 7 is inserted, the initial voltage is set by the voltage adjusting means 36. Next, when the start button 18 is pressed and the switch means 37 is closed, electricity is supplied at this initial voltage. During energization, molten resin flows into the detection hole 4 and pushes up the slide block 16, and when the pressure activates the microswitch 13 and an output signal is input to the control device 9, the voltage becomes lower than the initial voltage. can also be switched to a lower voltage. At the same time, the time from the start of energization of the initial voltage to the time of voltage switching is measured, and the latter energization time is determined by multiplying this by a predetermined coefficient. And this is timer 34
is output to . Next, an example of a control method by the control device 9 will be explained based on FIG. 4. At the time of fusion, first, the initial voltage is set to, for example, 40V by the voltage adjustment means 36, and then the connector 7 is inserted into the insertion port 2 (Step 40). The insertion is continued until the positioning terminal 12 contacts the terminal 5 and conductors A and B are electrically connected (step 4l). After the insertion is completed, the start button 18 is pressed (step 42) and the switch means 37 is closed. Then, heating wire 3 with an initial voltage of 40V
A current flows through the wire (step 43), and the heating of the heating wire 3 melts the resin around it (step 44), increasing the pressure. As a result, molten resin begins to flow into the detection hole 4 from the bottom of the hole, and the molten resin that flows in eventually pushes up the slide block 16 and activates the microswitch 13 (step 45). When the microswitch l3 is activated, its output signal is input to the CPU 31, and as a result, the voltage adjustment means 36 switches the voltage to a voltage lower than the initial voltage of 40V, for example, 15 to 30V based on the data from the ROM 33. (Step 46). At the same time C
P031 measures the time from the start of energization of the initial voltage until switching (step 47), and the later energization time is determined by multiplying this time by a predetermined coefficient (step 48), and the timer 34 starts timing. do(
Step 49). Then, heating and melting is performed at a later voltage. The energization time at the latter voltage is continued until the timer 34 times up (step 50), and after the time has elapsed, the voltage is output to the switch means 37 and the energization is stopped. i
During the ffi operation, the molten resin fills the gap between the hole 4 and the slide block 16, and then a portion of it flows into the small hole 14. When connector 7 is removed from insertion port 2 after fusion,
The resin that has flowed into the small hole 14 solidifies, and a bottle-shaped protrusion 19 as shown in FIG. 5 is formed. This confirms the completion of fusion. In the above embodiment, holes are provided in both insertion ports of the joint, and a microswitch and a slide block are provided in the connector. It may be provided only on the connector. FIG. 8 shows another example, in which the detection hole formed near the heating wire 22 from the surface of the insertion port 2l has a large diameter part 23a and a small diameter part 23b, and the slide block 24 is inserted. The large diameter portion 23a is formed so that the hole bottom has a specific depth depending on the type of joint.

The slide block 24 is connected to a slide resistor 26 embedded in the connector main body 25, and when the connector 27 is inserted into the insertion port 21 and connected, the slide block 24 hits the bottom of the hole in the large diameter portion 23a and is lifted. , the resistance value of the slide resistor 26 changes, and this data is input to the control device 51. As shown in FIG. 9, the control device 51 has a basic configuration consisting of a CPU 52, a ROM 53 in which a program for fusion is stored, and a RAM 54 in which various data for joints and fusion are stored. It is provided with timers 55 and 56, voltage adjustment means 57, and switch means 58, and a terminal 28, a positioning terminal 29, and a slide resistor 26 are connected to the CPU 52, respectively. FIG. 10 shows an example of a control method by the control device 28. As in the above embodiment, first, the voltage adjusting means 57
Set the initial voltage to 40V. Then connector 2
7 into the insertion port 2l until the positioning terminal 29 contacts the terminal 28 (steps 60, 61). As the slide block 24 is inserted, it hits the bottom of the hole in the large diameter portion 23a and is lifted, and the resistance value of the slide resistor 26 changes by the amount of displacement, and the type of joint is identified from this data (
Step 62) The initial and late energization times corresponding to the resistance values are read from the RAM 54 (Step 63).
After the insertion is completed, the start button 59 is pressed (step 64), the timer 55 is activated (step 65), and the switch means 58 is closed to turn on the power at an initial voltage of 40V (step 66). As a result, heating and melting is performed until the timer 55 times out, and when the time is up (step 67). Based on the data from the RAM 54, the voltage regulating means 57 switches the voltage to 15 to 30 V (step 68), and the first timer 55 is activated (step 69) to continue energizing at a low voltage (15 to 30 V).

Step 70 when the first timer 55 performs time amplification
), its output signal is input to the switch means 58, and the energization is stopped. The fusion device shown in FIG. 11 includes a voltage adjusting means 82 that adjusts the voltage when the joint 8l is energized, a voltage measuring means 83 and a current measuring means 84 that measure the voltage and current when energizing, and a voltage measuring means 83 and a current measuring means 84 when energizing. The control device 85 has a basic configuration consisting of a CPU 86, a ROM 87 in which a program for fusion is stored, and a RAM 8B in which various data are stored, and a timer 8.
9, a switch means 90, and a clock generation circuit (not shown), and each of the above means 82, 83 and 84 is a CPU.
It is connected to 86. The CPU 86 is a voltage measuring means 8
The electric power is calculated from the voltage measured from 3 and the current measured from the current measuring means 84, and the electric power is calculated from the relational expression between the energization time read from the RAM 88 and the supplied power by obtaining the input from the Kurofuku generation circuit. When the voltage value is higher than the voltage value calculated from the relational expression, the voltage adjustment means 82 is controlled to lower the voltage, and when it is lower than the voltage value, to increase the voltage. This is carried out until the timer 89, which is activated at the same time, completes the time amplification. The flowchart shown in FIG. 12 shows an example of a control method by the control device 85 of this embodiment. The voltage corresponding to the initial power obtained from the relational expression obtained by identifying the joint and the time required for fusion are set, the switch means 90 is closed, and power supply is started (step 9
1). As the power supply starts, each measuring means 83
and 84, the current ■ and the voltage V are measured (steps 92 and 93), and the electric power W is calculated based on this (steps 92 and 93).
Step 94). This power W is compared with the power value Wt (step 95) calculated from the relational expression (step 96),
When both sides do not lose, the voltage adjustment means 82 is controlled to adjust the voltage V to be higher or lower (Step 97).
The above operations are performed until the timer 89 times out (step 98), and when the time is up, the switch 90 opens and the supply is stopped. Effects of the Invention The present invention is configured as described above, and has the following effects. In cases where the energization time is divided into several sections and the voltage or current is lowered step by step, or the energization time is divided into the first and second periods, the temperature of the heating wire is raised to near the upper limit temperature in the first period, and then the voltage or current is lowered in the second period. If the voltage is made to decrease continuously, even if the maximum temperature of the heating wire is lower than that of conventional ones, it is possible to maintain the temperature of the fusion interface above the lower limit temperature for a long time, which prevents changes in environmental temperature and joints. Even if there are fluctuations in the heating wire and interface temperature due to the gap between the pipe and the pipe, dimensional tolerances of the joints and pipes, tolerances in the resistance value of the heating wire, etc., this temperature can be maintained within the appropriate temperature range, and the actual energizing time can be reduced. Even if the energization time is slightly different from the optimum energization time for fusion, the interface temperature can be kept within the appropriate temperature range. As a result, it is possible to deal with the factors that affect the heating wire and the fused interface with sufficient margin, so it is possible to take large dimensional tolerances for joints and pipes, and also to adjust the permissible temperature range of the environment and conduct current flow. You can expand your time tolerance. Similar effects to those described above can be obtained using methods and devices in which the power is gradually reduced. Regarding welding devices that have a small hole on the bottom that contacts the molten resin of a positioning detection switch or pressure sensor that is inserted into a detection hole, a protrusion is formed by the resin that flows into the small hole and solidifies after welding. This makes it relatively easy to check externally. If the connector connected to the insertion port of the fusion device is provided with a positioning means, the connection can be made accurately.
If a terminal is used as a positioning means and conducts when it comes into contact with the socket during connection, and the conduction can be indicated by a CRT, an indicator light, a buzzer, etc., it will be easy for the operator to check whether the connection has been made properly. You will be able to know.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of an electrofusine joint with a connector connected, and Figure 2 is a cross-sectional view of an electrofusine joint with a connector connected. 3 is a functional block diagram of the II device, FIG. 4 is a flowchart, FIG. 5 is a cross-sectional view of the main part of the electrofusion joint after fusion, and FIG. 6 is a fusion diagram according to the method of the present invention. A graph showing the relationship between the temperature of the heating wire and the fusion interface during deposition and time, FIG. 7 is a graph for the conventional method, and FIG. 8 is for the electrophage method.
7-A sectional view of the main parts showing another embodiment of the joint, FIG. 9 is a block diagram of another control device, FIG. 1θ is a flowchart of the same device, and FIG.
Fig. 12 is a flowchart of the same device, and Fig. 13 is a graph showing the relationship between electric power and the temperature of the heating wire and the fusion interface. 1.81. ．． Couplings 2, 21...Inserts 3, 22
・・Heating wire 4・・Detection hole 5・・Terminal 7, 27・
・Connector 9. 51.85...Control device 11.2
8...Terminal 12.29...Positioning terminal 13...Micro switch 14...Small hole 15...Air vent 16
．． 24...Slide block 18...Switch 2
6.. Slide resistor 31.52.86...CPU
32.53.87...ROM33.54.88...
R A M 34, 55, 56.89...Timer 3
6.57.82 Voltage adjustment means 37.58.90 Switch means No. lwJ Applicant Mitsui Petrochemical Industries Co., Ltd. Agent Patent attorney Koichi Sato Figure 4 MIO Figure 5

Claims (27)

[Claims] (1) A method for fusing electrofusion joints in which a heating wire is buried in the contact surface with the plastic pipe, and the welding with the pipe is performed by applying a predetermined amount of electricity to the heating wire to heat and melt the contact surface. A fusion method characterized in that the entire energization time for the joint is divided into several sections, and the voltage or current is set to decrease in stages. (2) A method for fusing electrofusion joints in which a heating wire is buried in the contact surface with the plastic pipe, and the welding with the pipe is performed by applying a predetermined amount of electricity to the heating wire to heat and melt the contact surface. A fusion welding method characterized in that the entire energization time to the joint is divided into an early period and a latter period, and the voltage or current is continuously lowered in the latter period. (3) Switching between voltage and current is performed when a pressure sensor detects the increase in pressure due to thermal expansion of molten resin heated and melted by a live heating wire, and when the pressure reaches a preset pressure. Claim 1 characterized in that
Or the fusion method described in 2. (4) The fusion method according to claim 3, wherein the joint is provided with a detection hole extending from the outer surface of the joint to the vicinity of the heating wire, and a pressure sensor is inserted into the hole. (5) The joint is provided with a detection hole that reaches from the outer surface of the joint to the vicinity of the heating wire, and switching of the voltage or current is performed inside the hole by the pressure caused by the thermal expansion of the molten resin heated and melted by the energized heating wire. The fusion method according to claim 1 or 2, characterized in that the level of the molten resin flowing into the molten resin is detected by a position detection switch, and the fusion is performed when the molten resin reaches a preset level. (6) Claim 4 or 4, wherein the detection hole is formed in the insertion port.
Described fusion method (7) The energization time and voltage or current switching time are set for each type of joint, and the joint is provided with an identification means for displaying the type of joint, and the information read by the sensor from the identification means is The fusion method according to claim 1 or 2, wherein the type of joint is identified based on the type of joint, and the voltage or current is switched at a set time corresponding to the type. (8) The fusion method according to claim 7, wherein the identification means is a hole bottom level of a detection hole formed in the insertion port, and the time setting is performed by a timer of a control device. (9) The fusion method according to claim 1 or 2, wherein each divided time is determined by multiplying the first divided time or the time before switching by a predetermined coefficient. (10) The welding method according to claim 1, wherein the electrical conduction time is divided into two periods, an early period and a latter period, and the latter period is set in a range of 1/3 to 1/1 times the time of the first period. (11) The energization time is divided into the first half and the second half, and the voltage and current in the second half are 1/3 to 3/4 of the voltage and current in the first half.
The fusion method according to claim 1, wherein the fusion bonding method is set to double the (12) A heating wire is buried in the contact surface with the plastic pipe,
In the fusion method of electrofusion joints, in which the fusion with the pipe is performed by heating and melting the contact surface by applying electricity, the voltage and/or current is controlled from the start to the end of energization, and the electric power is applied for a preset energization time. A fusion method characterized in that the welding is gradually reduced according to the relational expression between and electric power. (13) A heating wire is buried in the contact surface with the plastic pipe,
In a fusion device for electrofusion joints in which fusion with plastic pipes is performed by applying electricity, the current measurement means, the voltage measurement means, and the adjustment means for adjusting the current and/or voltage are measured from both measurement means. The power is calculated from the current and voltage, and when the power value calculated based on the relational expression between the preset energization time and the supplied power that gradually decreases over time is exceeded, the voltage and/or current is lowered to fall below the above power value. A fusing device, sometimes comprising a control means for controlling said regulating means so as to increase the voltage and/or current. (14) The control means includes a sensor that reads data regarding the type of joint from an identification means provided on the joint, and a storage means that stores a relational expression between electric power and energization time corresponding to the type of joint. Fusion device according to claim 13 (15) Bury a heating wire in the contact surface with the plastic pipe,
In the fusion device for electrofusion fittings, in which the fusion with the pipe is performed by applying a predetermined amount of electric power to the heating wire and heating and melting the contact surface, a detection hole that reaches from the outer surface of the joint to the vicinity of the heating wire is installed. A position detector is provided and fitted into the detection hole during fusion, is pushed and moved by the molten resin flowing into the hole from the bottom of the hole, detects the molten resin, and sends an output signal to a control device that controls energization. A fusion device characterized in that a switch or a pressure sensor is provided, and the position detection switch or pressure sensor has a small hole formed in the bottom surface that contacts the molten resin. (16) The fusion device according to claim 15, wherein the small hole has an inner diameter of about 1 to 3 mm and a depth of about 1 to 20 mm. (17) Claim 15: An air vent is formed at the back of the small hole.
Fusion device described (18) Claim 15 wherein the detection hole is formed in the insertion port.
Fusion device described (19) The fusion device according to claim 15, wherein the connector to be connected by being inserted into the insertion port is provided with positioning means for positioning at the time of connection. (20) The fusion device according to claim 19, wherein the positioning means is a positioning terminal, and whether or not the connection has been properly performed is confirmed by the terminal contacting the insertion port and establishing continuity. (21) The fusion device according to claim 20, further comprising a CRT, an indicator light, or a buzzer that indicates continuity. (22) The fusion device according to claim 15, wherein the position detection switch or the pressure sensor is provided on a connector connected to the insertion port. (23) The fusion device according to claim 15, wherein the joint is provided with identification means for identifying the type of the joint. (24) The fusion device according to claim 23, wherein the identification means is at the level of the bottom of a detection hole formed in the insertion port. (25) Claim 1, wherein the connector connected to the insertion port is provided with a limit switch that is activated by a pressure sensor and sends an output signal to a control device that controls energization.
Fusion device according to 5. (26) The fusion device according to claim 15, wherein the connector connected to the insertion port is provided with a multi-contact point or a variable resistor that is activated by a position detection switch and sends an output signal to a control device that controls energization. (27) The fusing device according to claim 15, wherein the position detection switch or the pressure sensor has a portion that comes into contact with the molten resin made of fluorocarbon resin or treated with fluorocarbon.