JP2660990B2 - Electric welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric welding apparatus. In particular, the present invention inserts the end of the pipe into the joint,
The present invention relates to an electric fusion bonding apparatus for applying a current to a heating element disposed on an inner peripheral surface of a joint to perform fusion (electrofusion) on an end of a pipe.

[0002]

2. Description of the Related Art An end of a thermoplastic pipe is inserted into a thermoplastic joint provided on an inner peripheral surface of a heating wire (electric resistance wire) wound in advance in a spiral shape, and current is applied to the heating wire to generate heat. Let
2. Description of the Related Art An electric fusion bonding system for melting and joining a joint surface of a joint and a pipe has been conventionally used.

[0003]

However, when connecting a pipe such as a gas pipe or a water pipe, water is likely to enter between the joint and the pipe because the work is performed outdoors. If fusion work is performed with water infiltrated between the joint and the pipe, heat will be taken away by the heat of vaporization of water, resulting in insufficient temperature rise at the joint between the joint and the pipe. In some cases, this cannot be done completely. In addition, if water has penetrated, water vapor generated by heating with the heating wire generates bubbles in the molten resin, so that the fusion strength between the joint and the pipe is reduced or the airtightness of the joint is reduced. There is a problem that lowers.

[0004] If the fusion bonding is incomplete and the fusion strength is low, there is a possibility that the joint of the underground pipe may be disconnected due to an earthquake or the like. In the case of a gas pipe or a water pipe, if the airtightness is reduced, there is a risk that an accident such as a gas leak or a water leak may occur.

[0005] Further, a step of drying and removing water by applying a current for a certain period of time at a relatively low temperature regardless of whether water exists between the joint and the pipe is added to the step before the joint is melted. An electrofusion apparatus has been proposed. However, in this device, the energization time is uniformly extended with or without water, and the work time is prolonged, thereby reducing the work efficiency. Furthermore, with this apparatus, even when drying is insufficient or when the joints and pipes are submerged and cannot be dried, the drying process ends after a certain period of time. Incomplete dressing and air bubbles are inevitable.

The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and an object of the present invention is to make the joint and the pipe improper when water has entered between the joint and the pipe. The purpose is to prevent complete joining.

[0007]

According to the first aspect of the present invention, the electric fusion bonding apparatus is inserted into the joint made of a synthetic resin and the joint by energizing a heating element disposed on the inner peripheral surface of the joint. In an electrofusion apparatus for fusing an end portion of a synthetic resin pipe, means for detecting a current value flowing through the heating element, and means for detecting a voltage value applied to the heating element, During the period from the start of energization to before the start of melting of the joint, the resistance value of the heating element is determined from the current value flowing through the heating element and the applied voltage value, and the resistance between the joint and the pipe is determined based on the time change rate of the resistance value. Means for detecting water.

[0008] In the electric fusion bonding apparatus according to the second aspect of the present invention, by energizing a heating element disposed on the inner peripheral surface of the joint, the synthetic resin joint and the synthetic resin pipe inserted into the joint are formed. In an electric fusion welding apparatus for fusion-bonding an end portion, a means for detecting a current value flowing through the heating element, a means for detecting a voltage value applied to the heating element, In the period before the start, the temperature of the heating element is obtained from the current value and the applied voltage value flowing through the heating element, and means for detecting water between the joint and the pipe based on the time rate of change of the heating element temperature. , Is provided.

According to a third aspect of the present invention, in the electrofusion apparatus according to the first or second aspect, when the judging means detects water between the joint and the pipe, the heat is applied to the heating element. Is stopped, and an abnormality is notified.

According to a fourth aspect of the present invention, in the electrofusion apparatus according to the first or second aspect, when the determination means detects water between the joint and the pipe, the heating element is provided for a predetermined time. The power supply to the heating element is interrupted, and thereafter, the power supply to the heating element is automatically restarted.

[0011]

When the electric welding apparatus is energized by the heating element, the joint surface between the joint and the pipe is melted and joined by fusion. However, if water has penetrated between the fitting and the pipe,
Since the heat generated from the heating element is consumed as heat of evaporation of water, the rate of change of the heating element temperature over time is smaller than normal, and the heat can enter between the fitting and the pipe based on the rate of change of the heating element temperature over time. Water that is flowing can be detected.

On the other hand, the resistance value of the heating element can be known by detecting the conduction current and the applied voltage of the heating element. Since the resistance value of the heating element changes with its temperature (for example, in the case of a metal resistor, the resistance value increases as the temperature rises), the time change rate of the heating element temperature is the time change of the resistance value of the heating element. You can know from the rate.

Therefore, in the electric fusion welding apparatus according to the first aspect, the electric fuser penetrates between the joint and the pipe based on the time rate of change of the resistance value obtained from the current flowing through the heating element and the applied voltage. Water can be detected.

In addition, in this electrofusion apparatus,
Since the temperature of the heating element is determined by detecting the resistance value of the heating element, the temperature of the heating element can be directly determined, and measurement errors and variations can be reduced. Further, since water is detected based on the time rate of change of the resistance value of the heating element, the detection of water is less likely to be affected by the environmental temperature, and the detection accuracy of water is stabilized. Further, since the resistance value is obtained from the applied voltage and the current supplied to the heating element, the resistance value can be accurately obtained irrespective of the fluctuation of the output of the electric fusion welding apparatus.

Further, as described above, the resistance value of the heating element can be determined from the current flowing through the heating element and the applied voltage, and there is a certain relationship between the resistance value of the heating element and the temperature of the heating element. ing. Therefore, the heating element temperature can be obtained directly from the current flowing through the heating element and the applied voltage, as in the electric fusion welding apparatus according to claim 2, and the joint and pipe are connected based on the time change rate of the heating element temperature. It is also possible to detect water that has entered.

According to the electrofusion apparatus of the first or second aspect, the time rate of change of the temperature of the heating element or the time rate of change of the resistance value is obtained and compared with the normal value. , Water that has entered between the joint and the pipe can be detected.

When water intrusion is detected, the power supply to the heating element is stopped to notify the operator of the abnormality. Therefore, it is possible to prevent the joint quality of the joint and the pipe from deteriorating, and to avoid troubles and accidents due to poor joints in advance. In particular, since water is detected during the period from the start of energization of the heating element to the start of melting of the joint, when energization is stopped, the joint between the joint and pipe is wiped or dried by applying hot air. After that, the joining operation can be performed again.

Further, in the embodiment of the present invention, when water is detected between the joint and the pipe, the power supply to the heating element is interrupted for a predetermined time, and then the power supply to the heating element is automatically restarted. Therefore, water can be dried and removed by the residual heat of the heating element during the interruption of the current supply to the heating element, and the joint and the pipe can be fusion-bonded by restarting the current supply to the heating element.
Therefore, it is not necessary to separate the joint and the pipe, wipe the water, and then insert the pipe into the joint again, thereby improving the working efficiency.
On the other hand, when the water is not dried and removed due to the residual heat of the heating element, the water is detected again and the current is interrupted even if the current is restarted. Therefore, if the drying of the water is inadequate forever or the joint is submerged, the joint and the pipe are not connected, and incomplete joining can be prevented.
Also, if no water is detected between the fitting and the pipe,
Since a process for drying and removing water does not occur, the working efficiency is not reduced as compared with a conventional electrofusion apparatus.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a schematic front view showing the appearance of an electric fusion welding apparatus 1 according to one embodiment of the present invention, and a cross section of a joint 2 and a pipe 3. The electrofusion apparatus 1 includes an electrofusion apparatus main body (controller) 4, a connection cable 5, and a power cable 6. The electric welding apparatus main body 4 has a start switch 7 and a reset switch 8 on the front.
And a display device 9 such as a liquid crystal display panel. The start switch 7 is a switch for starting energization of the heating wire 10 of the joint 2. The reset switch 8 is a switch for clearing the abnormality when energization is interrupted on the way or when an abnormality is detected. The display device 9 is for displaying operation instructions, operating conditions during operation, abnormalities, and the like. Note that a buzzer 11 is provided inside.

A power plug 12 for connecting to a commercial power supply 25 is provided at the end of the power cable 6 connected to the main body 4 of the electrofusion apparatus. In addition, a joint connector 13 for connecting to the joint 2 is provided at a distal end of the connection cable 5 connected to the electric fusion bonding apparatus main body 4.

(Joint and Pipe) The joint 2 has a tubular shape with both ends opened, and at least the inner peripheral surface is formed of a thermoplastic resin such as polyethylene or engineering plastic, and the inner peripheral surface is made of the same material as the joint resin. The heating wire 10 (resistor) covered with the resin is spirally wound and disposed. A cable connecting portion 14 for connecting the joint connector 13 of the connection cable 5 is provided on an outer surface of the joint 2, and a terminal pin 15 electrically connected to the heating wire 10 is located in the cable connecting portion 14. . Thus, when the joint connector 13 of the electric fusion bonding apparatus 1 is connected to the cable connection portion 14, the electric fusion bonding apparatus 1 is connected to both ends of the heating wire 10 via the terminal pins 15. At least the outer peripheral surface of the end of the pipe 3 is formed of a thermoplastic resin. The pipe 3 is inserted into the joint 2 deeply until it hits a stopper 16 protruding from the inner peripheral surface of the joint 2.

(Circuit Configuration) FIG.
FIG. 2 is a block diagram showing a circuit configuration of a power control unit 17, a voltage detection unit 18, a current detection unit 19, a resistance value calculation unit 20, a temperature calculation unit 21, a time change rate calculation unit 22,
It comprises a memory 23 and a water detection unit 24.

The power control unit 17 is a part that performs a main function of the electric fusion welding apparatus 1, and supplies power obtained from a commercial power supply 25 to the heating wire 10 of the joint 2 connected via the connection cable 5. The heating wire 10 generates heat at a controlled temperature. The power control unit 17 energizes the heating wire 10 according to a predetermined control method according to a program stored in the memory 23 in advance, and causes the heating wire 10 to generate heat. For example, the output of the power control unit 17 may be subjected to constant current control, constant voltage control, or constant power control, or power may be supplied to the heating wire 10 according to a predetermined energization pattern.

The voltage detecting unit 18 controls the power control unit 1 during energization.
7, a voltage value V applied to the heating wire 10 (that is, a voltage between both ends of the heating wire 10) is detected. The current detection unit 19 detects the current value I supplied to the heating wire 10 by the power control unit 17.

The resistance value calculating section 20 calculates the resistance value of the heating wire 10 from the applied voltage V of the heating wire 10 detected by the voltage detecting section 18 and the conduction current I of the heating wire 10 detected by the current detecting section 19. Find R = V / I. As the resistance value calculation unit 20, for example, a division circuit can be used. Further, the temperature calculation unit 21 obtains the temperature T of the heating wire 10 based on the relationship between the resistance value of the heating wire 10 and the temperature of the heating wire 10 stored in the memory 23 in advance. The time change rate calculation unit 22 calculates a time change rate (increase rate) ΔT / Δt of the temperature T of the heating wire 10.
(T indicates the energizing time). The process here is
The temperature T may be calculated continuously, and the change in the temperature T may be differentiated by the time change rate calculator 22 to obtain the time change rate ΔT / Δt. It is sufficient to determine the temperatures T1 and T2 at two points in the period before the start of melting of the joint 2 and divide the temperature difference ΔT = T2−T1 by the time interval Δt.

The water detecting section 24 detects whether or not water has entered between the joint 2 and the pipe 3 based on the time rate of change of the temperature obtained by the time rate calculating section 22.
That is, the time change rate of the heating wire temperature in the case where there is no water between the joint 2 and the pipe 3 and the drying is performed is stored in the memory 23 in advance. The water detection unit 24 determines the presence or absence of water by comparing the time change rate of the heating line temperature obtained by the time change rate calculation unit 22 with the value of the normal time change rate in the memory 23. . Specifically, if the value of the obtained time change rate is smaller than the case where it is normal, the joint 2
It is determined that water has penetrated between the pipe 3 and.

If water has not entered, the power control unit 17
Continues to supply electricity to the heating wire 10 and the joint 2 and the pipe 3
And the water detection unit 24 detects the joint 2 and the pipe 3
When water is detected during this period and a signal indicating an abnormality is output to the power control unit 17, the power control unit 17 stops operating. At the same time, the water detection unit 24 sounds the buzzer 11 to notify the worker of the abnormality and also causes the display device 9 to display the abnormality.

The power control unit 17 and the resistance value calculation unit 2
The water detection unit 24 and the like are configured using an IC, a microcomputer (CPU), or the like.

(Fusing Method) FIG. 3 is a flow chart for explaining an operation procedure when connecting the joint 2 and the pipe 3 by the above-described electric fusion apparatus 1. First, when the start switch 7 is pressed (S31) to start energizing the heating wire 10, the current and voltage of the heating wire 10 are stabilized until the heating wire 10 is stabilized.
The current detection unit 19 detects the value of the current flowing through the heating wire 10, the voltage detection unit 18 detects the voltage applied to the heating wire 10 (S 32), and the resistance value calculation unit 20 detects the conduction current and the applied voltage. The resistance value of the heating wire 10 is determined from the value (S33), and then the resistance value of the heating wire 10 is converted into the heating wire temperature by the temperature calculation unit 21 (S34). Thus, the process of detecting the current and voltage of the heating wire 10 and obtaining the heating wire temperature until the heating wire temperature reaches the upper limit set temperature (set to a temperature lower than the temperature at which the joint resin starts melting) ( S32 to S35) are repeated several times, and the data of the heating line temperature is sampled at several points. Thus,
When the heating wire 10 reaches the upper limit set temperature (S35), the sampling time interval Δt and the sampling data [for example,
T1, T2] and the rate of change of the heating wire temperature with time [(T2
−T1) / Δt] (S36). Next, the calculated value of the time change rate is compared with a specified value (set to a value smaller than the time change rate in a normal case by a fixed value) (S37), and if the value is larger than the specified value. If it is determined that there is no water intrusion, the energization is continued, and the joint 2 and the pipe 3 are fused and connected (S38).

On the other hand, if the time rate of change of the temperature of the heating wire is smaller than a specified value, the power supply to the heating wire 10 is stopped (S39), the buzzer 11 is sounded to inform the operator and display. Display indicating that water is present on the device 9 (S4
0). When the power supply is stopped, the joint 2 and the pipe 3 are dried by wiping with a cloth or applying hot air, and then the joint 2 and the pipe 3 are connected again and the reset switch 8 is pressed (S41). The state is released (S42), and the power supply is started again by pressing the start switch 7 (S43).

(Relationship between Temperature of Heating Wire and Presence or Absence of Water) FIG.
As shown in the right half of the joint 2 of FIG.
Is inserted, the joint connector 13 of the connection cable 5 is connected to the cable connection portion 14, and the heating wire 1 is
Consider a case in which energization is started to zero. FIG. 4 is a diagram showing the relationship between the energizing time and the temperature of the heating wire 10 at this time, and a solid line a indicates a change in the heating wire temperature when water does not exist between the joint 2 and the pipe 3. Dotted chain line B shows joint 2 and pipe 3
3 shows an initial change in the heating wire temperature when water invades during the heating. A period A1 indicates the period from the start of energization to immediately before the joint 2 starts melting. A period A2 indicates a period from when the joint resin near the heating wire 10 starts to melt and when the melted joint resin sufficiently adheres to the pipe 3. A3 indicates a state in which the melted resin is in close contact with the pipe 3, and the joint surfaces of the joint 2 and the pipe 3 are mutually melted. 5 to 7 are views showing the state of the joint 2 and the pipe 3 in each of the periods A1 to A3, and the hatched portions in FIGS. I have.

FIG. 4 shows the state of the joint 2 and the pipe 3 from the start of energization to the joining in a normal case.
5 and FIG. When energization of the joint 2 is started, as shown in FIG.
Temperature rises. The slope (time rate of change) of the temperature rise in each of the periods A1 to A3 is represented by the calorific value of the heating wire 10 and
It is determined by the thermal conductivity between the heating wire 10 and the pipe 3 and the heat capacity of the joint 2 and the pipe 3. First, in the period A1 immediately after energization, the temperature of the heating wire 10 gradually increases from the initial environmental temperature. In this process, joint 2
As shown in FIG. 5, the joint resin near the heating wire 10 is partially in contact with the pipe 3, but is not in close contact with the pipe 3, as shown in FIG. The temperature is relatively small, and therefore, the slope of the temperature rise of the heating wire 10 is relatively steep.

Next, in the period A2, the joint resin around the heating wire 10 starts to melt as shown in FIG. 6, and the melted joint resin starts to adhere to the pipe 3. At this time, due to the heat of fusion of the joint resin, the slope of the temperature rise of the heating wire 10 starts to be gentle, and further, the joint resin comes into close contact with the pipe 3 to increase the heat capacity and the thermal conductivity. The slope becomes even gentler.

Next, when the joint resin sufficiently adheres to the pipe 3, the process of the period A3 is started. When the joint resin melts and comes into close contact with the pipe 3, the heat capacity of the heating wire 10 increases. Therefore, if the heating value of the heating wire 10 is the same, the slope of the temperature rise in the period A3 becomes the slope of the temperature rise in the period A1. It becomes gentler than the inclination. If the temperature of the heating wire 10 continues to rise in this state, the temperature reaches a temperature at which the resin of the joint 2 and the resin of the pipe 3 are sufficiently fused, as shown in FIG. At this point, the current supply to the heating wire 10 is terminated, and the temperature of the joint 2 and the pipe 3 is reduced to near the ambient temperature to complete the joining.

On the other hand, between the joint 2 and the pipe 3, water β
Consider the case where is infiltrated. In this case, as shown in FIG. 8, since water β exists between the heating wire 10 and the pipe 3, the heat conductivity increases and the heat of vaporization of the water deprives the heat. As a result, in the period A1,
As shown by the two-dot chain line B in FIG. 4, the slope of the temperature rise of the heating wire 10 becomes gentle. Therefore, when the inclination of the temperature rise of the heating wire 10 falls below a specified value as compared with a normal value stored in the memory 23 in advance, water is supplied between the joint 2 and the pipe 3. It can be determined that it has been detected.

Therefore, the electric fusion bonding apparatus 1 of the above embodiment
When the time rate of change of the temperature obtained by the time rate calculating unit 22 is equal to or less than the specified value, the water detecting unit 24 determines that water has entered between the joint 2 and the pipe 3. You can do it.

As can be seen from FIG. 4, water can be detected from the temperature of the heating wire 10 instead of the time rate of change of the heating wire temperature. However, when the temperature of the heating wire 10 is used, the temperature is affected by the ambient temperature. On the other hand, based on the rate of change of the heating wire temperature with time, the influence of the ambient temperature is less likely to occur, and thus the necessity of correcting the effect of the ambient temperature is reduced, and a stable result can be obtained.

In the present invention, the time change rate of the heating wire temperature is directly obtained from the resistance value of the heating wire 10, so that the time change rate of the heating wire 10 can be obtained stably. For example, when a temperature measuring device such as a thermocouple or a thermistor is brought into contact with the vicinity of the heating wire 10 in order to measure the temperature of the heating wire 10, a thermal resistance (resin resin) between the heating wire 10 and the temperature measuring device is required. The measurement result varies due to the variation of the measurement result, and the measurement result is not stable. On the other hand, if it is determined from the resistance value of the heating wire 10, the heating wire temperature can be detected stably. The heating wire 1 having a large temperature coefficient of resistance value.
If 0 is used, the detection sensitivity is further improved.

Moreover, since the resistance value of the heating wire 10 is obtained from the instantaneous current detected by the current detection unit 19 and the instantaneous voltage detected by the voltage detection unit 18, the current value and voltage value of the heating wire 10 fluctuate. In this case, the resistance value can be determined precisely. On the other hand, the power control unit 17 of the constant current control
In the case where only the voltage value of the heating wire 10 is monitored using the power control unit 17 or only the current value of the heating wire 10 is monitored using the power control unit 17 of the constant voltage control, the output value of the power control unit 17 varies. The accuracy of the obtained resistance value is affected by fluctuations in the power supply voltage and the like, and it is difficult to accurately measure the resistance value.

Furthermore, since water is detected from the time change rate of the heating wire temperature in the period A1 before the start of melting of the joint resin from the start of energization, it is possible to reliably detect water intrusion at an early stage. it can. In particular, since the joint resin is not melted, the joint 2 can be wiped or dried and reused.

(Second and Third Embodiments) In the above-described embodiment, the resistance value is determined from the applied voltage and the conduction current of the heating wire 10, the heating wire temperature is further determined, and the time change rate of the heating wire temperature is used. Although the intrusion was detected, if the heating wires 10 are the same, the relationship between the resistance value and the heating wire temperature is determined,
The configuration of FIG. 2 can be simplified. For example, the temperature calculating unit 21 can directly determine the heating wire temperature from the applied voltage and the conduction current of the heating wire 10. In that case, as shown in FIG. 9, the resistance value calculation unit 20 can be omitted, and the operation flow can be simplified accordingly.

Similarly, the intrusion of water can be directly detected from the rate of change of the resistance value of the heating wire 10 with time. In that case, as shown in FIG. 10, the temperature calculation unit 21 can be omitted. However, the time change rate calculation unit 22 calculates the time change rate of the resistance value, and the water detection unit 24 detects the infiltration of water based on the time change rate of the resistance value.

(Fourth Embodiment) In the first embodiment,
If water has penetrated between the joint 2 and the pipe 3, the power supply is stopped. However, when water is detected,
After the power supply is interrupted for a certain period of time and the water is dried by the residual heat of the heating wire, the power supply may be automatically started again to connect the joint 2 and the pipe 3. FIG. 11 shows an operation flow chart of the electrofusion apparatus of this embodiment. Note that the circuit configuration of this embodiment is the same as the block diagram of FIG.

The operation will be described with reference to the flowchart of FIG. When the start switch 7 is pressed to start energization, the voltage detection unit 18 detects the applied voltage of the heating wire 10 and the current detection unit 19 detects the energization current of the heating wire 10. The time change rate is obtained (S31 to S36). Next, the value of the obtained time change rate is compared with a specified value that specifies an incompatible value (S3).
7) If it is larger than the specified value, it is determined that there is no water intrusion, and the energization is continued, and the joint 2 and the pipe 3 are fused and connected (S38).

If water does not exist between the joint 2 and the pipe 3 from the beginning, the drying step by interruption of the energization as described later is not executed, so that the operation becomes the same as the operation of the ordinary electric fusion welding apparatus. The joining operation can be performed efficiently without lengthening the wearing operation.

On the other hand, when the time rate of change of the heating wire temperature is smaller than the specified value, the power supply to the heating wire 10 is temporarily stopped (S45), and after the power supply is stopped for a predetermined time, Power supply to the heating wire 10 is automatically restarted (S4
6). When the energization is resumed, steps S32 to S36 are performed again.
Is repeated at step 37 to determine whether or not water remains. That is, the heating wire 1 during the power interruption period
When the water is dried and removed by the residual heat of 0 or the heat of the heating wire 10 at the time of re-energization, the time change rate of the heating wire temperature becomes larger than a specified value (S37), and the energization is continued.
The joint 2 and the pipe 3 are fusion bonded (S38).

If the water is not sufficiently dried and removed during the power supply interruption period and remains, the time change rate of the heating wire temperature is smaller than the specified value (S37), and the power supply is temporarily stopped again (S45). ), Power is supplied again after a predetermined time has passed (S
46). Therefore, even when the amount of water entering between the joint 2 and the pipe 3 is large, as shown in FIG.
By repeatedly interrupting and re-energizing the current to zero, water can be gradually dried and removed, and finally the joint 2 and the pipe 3 can be joined.

However, when the joint 2 and the pipe 3 are immersed in the water β as shown in FIG. Water cannot be removed by drying repeatedly. For this reason,
The number of interruptions of energization is counted, and if the obtained time rate of change of the heating wire temperature is smaller than a specified value (S37), it is determined whether or not the number of interruptions of energization is equal to or less than the specified number (S44). If so, the interruption and re-energization (S
45, S46) are repeated, but when the number of times exceeds a specified number, the power supply to the heating wire 10 is stopped (S39), the buzzer 11 is sounded to notify the operator, and the display device 9 is displayed with water (S40). .

Since the interruption of the energization and the re-energization are performed before the joint 2 is melted, the joint 2 does not melt even when the joint 2 and the pipe 3 are not finally connected. The joint 2 and the pipe 3 can be reused.

[Brief description of the drawings]

FIG. 1 is a diagram showing an external appearance of an electric fusion welding apparatus according to an embodiment of the present invention and a cross section of a joint and a pipe.

FIG. 2 is a block diagram showing a circuit configuration of the electric fusion bonding apparatus according to the first embodiment.

FIG. 3 is an operation flow chart of the electric fusion bonding apparatus according to the first embodiment;

FIG. 4 is a diagram illustrating a relationship between an energizing time and a temperature of the heating wire (resistance value of the heating wire) when the heating wire of the joint is heated using the electric fusion bonding apparatus.

FIG. 5 is a cross-sectional view illustrating a state of a joint and a pipe during a period A1.

FIG. 6 is a sectional view showing a state of a joint and a pipe in a period A2.

FIG. 7 is a cross-sectional view illustrating a state of a joint and a pipe during a period A3.

FIG. 8 is a cross-sectional view showing a state in a period A1 of a joint and a pipe into which water has entered.

FIG. 9 is a block diagram showing a circuit configuration of an electrofusion apparatus according to another embodiment of the present invention.

FIG. 10 is a block diagram showing a circuit configuration of an electrofusion apparatus according to still another embodiment of the present invention.

FIG. 11 is a flowchart illustrating the operation of an electrofusion apparatus according to still another embodiment of the present invention.

FIG. 12 is a diagram showing a relationship between an energizing time and a heating wire temperature when heating a heating wire of a joint using the electric fusion bonding apparatus according to the embodiment.

FIG. 13 is a cross-sectional view showing a state of a joint and a pipe submerged in water.

[Explanation of symbols]

 2 Joint 3 Pipe 4 Electric fusion splicer body 9 Display device 10 Heating wire 11 Buzzer 17 Power control unit 18 Voltage detection unit 19 Current detection unit 20 Resistance value calculation unit 21 Temperature calculation unit 22 Time change rate calculation unit 24 Water detection unit

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takuhide Nakayama 3-9-20 Togoshi, Shinagawa-ku, Tokyo Hirata Kiko Co., Ltd. (56) References JP-A-7-164530 (JP, A) JP-A-7 -164532 (JP, A) JP-A-6-331087 (JP, A) JP-A-1-266393 (JP, A)

Claims (4)

(57) [Claims] An electric power for fusing a synthetic resin joint and an end of a synthetic resin pipe inserted into the joint by energizing a heating element disposed on an inner peripheral surface of the joint. In the fusion-bonding apparatus, a unit that detects a current value flowing through the heating element; a unit that detects a voltage value applied to the heating element; and Means for determining a resistance value of the heating element from a current value flowing through the heating element and an applied voltage value, and detecting water between the joint and the pipe based on a time change rate of the resistance value. 2. An electric power supply for applying heat to a heating element disposed on the inner peripheral surface of the joint to melt-bond the synthetic resin joint and the end of the synthetic resin pipe inserted into the joint. In the fusion-bonding apparatus, a unit that detects a current value flowing through the heating element; a unit that detects a voltage value applied to the heating element; and Means for determining the temperature of the heating element from a current value flowing through the heating element and an applied voltage value, and detecting water between the joint and the pipe based on a time change rate of the heating element temperature. 3. The electric power generator according to claim 1, wherein when the determination means detects water between the joint and the pipe, the power supply to the heating element is stopped to notify an abnormality. Fusion welding equipment. 4. When the determining means detects water between the joint and the pipe, the power supply to the heating element is interrupted for a predetermined time, and then the power supply to the heating element is automatically restarted. The electric fusion bonding apparatus according to claim 1 or 2, wherein