JP2819011B2 - 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]

In order to connect a joint to a pipe in an electrofusion system, the pipe must be completely inserted into the joint. However, whether or not the pipe has been inserted to a sufficient depth in the joint cannot be confirmed from outside the joint. In particular, after the joint and the pipe are fusion-bonded, the pipe cannot be reinserted into the joint, and an inspection for insufficient insertion of the pipe cannot be performed. For this reason, conventionally, it has been difficult to prevent deterioration of the fusion quality due to insufficient insertion of the pipe into the joint.

[0004] For example, if the welding of the joint and the pipe is performed in a state where the pipe is not completely inserted into the joint, the joint and the pipe cannot be completely fused because the joint area of the joint and the pipe is insufficient. However, there is a problem that the fusion strength is reduced.

[0005] Further, if the joint area between the joint and the pipe is insufficient, a gap may be generated between the joint and the pipe. For example, in a gas pipe or a water pipe, gas leakage or liquid leakage from a joint between the joint and the pipe may occur. There was a risk of leakage.

[0006] If the amount of the pipe inserted into the joint is insufficient, the temperature of the heat generating wire rises abnormally at a place where the pipe is not in contact with the pipe during the fusion splicing operation, and there is a danger of smoking or ignition. there were.

Conventionally, in order to prevent insufficient insertion of a pipe into a joint, an insertion line indicating an appropriate insertion depth of the pipe is drawn by hand on the outer peripheral surface of the pipe using magic ink or the like, and inserted. The pipe is inserted up to the line. Therefore, the on-site work becomes troublesome, and the work efficiency is greatly reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to detect a pipe connected to a joint with insufficient insertion and to perform fusion due to insufficient insertion of the pipe. An object of the present invention is to make it possible to easily detect abnormalities or deterioration in quality.

[0009]

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, After the start of energization and after the joint resin melts and comes into close contact with the pipe, 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 to the joint is determined based on the time change rate of the resistance value. Means for detecting the insufficient insertion of the pipe.

The electric fusion welding apparatus according to the second aspect of the present invention is characterized in that a heating element disposed on the inner peripheral surface of the joint is energized to thereby connect the synthetic resin joint and the synthetic resin pipe inserted into the joint. In an electric fusion bonding apparatus for fusing the ends, a means for detecting a current value flowing through the heating element, a means for detecting a voltage value applied to the heating element, After melting and contact with the pipe, the temperature of the heating element is determined from the current value and the applied voltage value flowing through the heating element, and the insufficient insertion of the pipe into the joint is determined based on the time change rate of the heating element temperature. Detecting means.

According to the third aspect of the present invention, the electric fusion bonding apparatus is configured to connect a synthetic resin joint and a synthetic resin pipe inserted into the joint by energizing a heating element disposed on an inner peripheral surface of the joint. In an electrofusion apparatus for fusing an end portion, means for detecting a current value flowing through the heating element, means for detecting a voltage value applied to the heating element, and a current flowing through the heating element The resistance value of the heating element is determined from the value and the applied voltage value, and from the start of energization to immediately before the start of melting of the joint,
From the start of melting of the joint until the joint resin adheres to the pipe,
Means for detecting insufficient insertion of the pipe into the joint based on the average value of the rate of change of the resistance value with time from each period after the melted joint resin comes into close contact with the pipe.

The electric fusion welding apparatus according to the fourth aspect of the present invention is characterized in that a current is applied to a heating element disposed on the inner peripheral surface of the joint, thereby forming a joint between the synthetic resin and the synthetic resin pipe inserted into the joint. In an electrofusion apparatus for fusing an end portion, means for detecting a current value flowing through the heating element, means for detecting a voltage value applied to the heating element, and a current flowing through the heating element The temperature of the heating element is determined from the value and the applied voltage value, from the start of energization to immediately before the start of melting of the joint, from the start of melting of the joint until the joint resin adheres to the pipe,
Each period after the melted joint resin adheres to the pipe ~
And means for detecting insufficient insertion of a pipe into a joint based on the average value of the time rate of change of temperature in the above.

[0013] The embodiment described in claim 5 is the first embodiment.
In the electrofusion apparatus according to 2, 3, or 4, when the means for detecting insufficient insertion of the pipe detects insufficient insertion of the pipe into the joint, the power supply to the heating element is stopped, and an abnormality is detected. The feature is to inform.

[0014]

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, when the pipe is not completely inserted into the joint, a part of the heating element provided in the joint does not completely contact the pipe, so that the heat conductivity and the heat capacity between the heating element and the pipe are reduced. As a result, the time rate of change of the temperature of the heating element is greater than when the pipe is completely inserted, and it is possible to detect insufficient insertion of the pipe into the joint from the time rate of change of the temperature of the heating element.

On the other hand, the resistance value of the heating element can be known by detecting the current flowing through the heating element and the applied voltage. 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 electrofusion apparatus according to the first or third aspect, the insufficient insertion of the pipe into the joint is determined based on the time rate of change of the resistance value obtained from the current flowing through the heating element and the applied voltage. 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 the insufficient insertion of the pipe is detected based on the rate of change of the resistance value of the heating element with time, the influence of the environmental temperature is reduced, and the detection accuracy 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 obtained 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, as in the electric fusion bonding apparatus according to claim 2 or 4, the temperature of the heating element can be obtained directly from the current flowing through the heating element and the applied voltage. Shortage of pipe insertion can be detected.

In the electrofusion apparatus according to any one of the first to fourth aspects, the time change rate of the heating element temperature or the time change rate of the resistance value is obtained and compared with a normal value. Insufficient insertion of a pipe into a joint can be detected .

In the case of detecting the insufficient insertion of the pipe, the power supply to the heating element is stopped,
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. Therefore, it is not necessary to mark an insertion line on a pipe in order to check for insufficient insertion as in the related art, and the operation can be simplified.

[0021]

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 engineered 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 an insufficient insertion detecting section 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 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. However, simply, two points separated by the time Δt may be used. , The temperatures T1 and T2 of the heating wire 10 at
It is sufficient to obtain the temperature difference ΔT = T2−T1 by dividing by the time interval Δt.

The under-insertion detecting section 24 detects whether the pipe 3 is completely inserted into the joint 2 or is under-inserted based on the time rate of change of the temperature obtained by the time rate calculating section 22. I do. That is, the time change rate of the heating wire temperature when the pipe 3 is completely inserted into the joint 2 is stored in the memory 23 in advance. The shortage of insertion detection unit 24 compares the time change rate of the heating wire temperature obtained by the time change rate calculation unit 22 with the value of the time change rate in the memory 23 in a normal case, and detects that the pipe 3 is not sufficiently inserted. Determine if it is not. For example, as will be described later, if the value of the time change rate obtained during the period A3 after the start of energization and the melted joint resin comes into close contact with the pipe is larger than the normal case, the insertion amount of the pipe 3 into the joint 2 Is determined to be insufficient.

If the pipe 3 is completely inserted, the power control unit 17 continues to supply electricity to the heating wire 10 and
And the pipe 3 are fusion-bonded, but the insufficient insertion detection unit 24 detects the insufficient insertion of the pipe 3 into the joint 2 and
When a signal indicating an abnormality is output to 7, the power control unit 17 stops operating. At the same time, the insertion shortage detection unit 24
1 to notify the worker of the abnormality and display device 9
Also display the abnormality.

The power control unit 17 and the resistance value calculation unit 2
0, the insufficient insertion 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 the operation procedure when the joint 2 and the pipe 3 are connected by the electric welding apparatus 1 as described above. 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). Next, it is determined whether or not the obtained heating wire temperature has reached the temperature at which detection is started (S35). Here, the temperature at which the detection is started is set to the temperature of the heating wire corresponding to the initial stage after the joint resin melted by the start of the current supply to the heating wire 10 and adhered to the pipe. Until the heating wire temperature reaches the detection start temperature, the heating wire temperature is repeatedly detected (S32 to S3).
4).

When it is confirmed that the temperature of the heating wire has become equal to or higher than the temperature at which detection is started (S35), the current detection unit 1
(S36) The resistance value of the heating wire 10 is determined from the current flowing through the heating wire 10 detected by the step 9 and the applied voltage detected by the voltage detection unit 18 (S37). It is converted to a temperature (S38). This process is repeated until the temperature at which the detection is completed is reached (S39), so that heating line temperature data is sampled at a plurality of points in a period A3 after the joint resin has adhered to the pipe (S39).
36 to S38), the time rate-of-change calculating unit 22 calculates the time rate of change of the heating line temperature in the period A3 based on the collected data of the heating line temperature (S40). The temperature at the end of detection is also set to the temperature of the heating wire corresponding to the initial stage after the energization of the heating wire 10 is started and the melted joint resin adheres to the pipe, and is set to a temperature higher than the temperature at the start of detection. Have been.

Next, the value of the obtained time change rate is set to a specified value that defines an incompatible value (set to a value larger than the time change rate when the pipe 3 is completely inserted by a certain value). After the comparison (S41), if it is smaller than the specified value, it is determined that the pipe 3 is completely inserted into the joint 2 and the energization is continued, and the joint 2 and the pipe 3 are fused and connected (S41).
42).

On the other hand, when the time rate of change of the temperature of the heating wire is larger than the specified value, the power supply to the heating wire 10 is stopped (S43), the buzzer 11 is sounded to inform the operator and display. A message indicating that the pipe is insufficiently inserted is displayed on the device 9 (S44).

(Relationship between Temperature of Heating Wire and Pipe Insertion Amount)
As shown in the right half of the joint 2 in FIG. 1, the pipe 3 is inserted into the joint 2, the joint connector 13 of the connection cable 5 is connected to the cable connecting portion 14, and the heating wire 10 is energized from the electric fusion splicer 1. Consider when it starts. FIG. 4 is a diagram showing a 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 the pipe 3 is completely inserted into the joint 2. Dotted chain line is pipe 3
Shows the change in the heating wire temperature when the insertion of the wire is incomplete. 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. FIGS. 5 to 7 show the respective periods A.
It is a figure which shows the state of the joint 2 and the pipe 3 in 1-A3, and the shaded part in FIGS. 5-7 has shown the fusion part (alpha) of the joint 2 and the pipe 3. FIG.

Hereinafter, when the pipe 3 is completely inserted into the joint 2, the state of the joint 2 and the pipe 3 from the start of energization to the joining is shown by the solid line A in FIG.
This will be described with reference to FIG. When energization of the joint 2 is started, FIG.
As shown in (2), the temperature of the heating wire 10 of the joint 2 increases. The slope (time rate of change) of the temperature rise in each of the periods A1 to A3 is determined by the amount of heat generated by the heating wire 10, 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, the resin of the joint 2 has not been melted yet, and as shown in FIG.
Is partially in contact with the pipe 3 but is not in close contact with it, so that the heat capacity and the thermal conductivity are relatively small, so that the slope of the temperature rise of the heating wire 10 is relatively steep. Has become.

Next, in the period A2, as shown in FIG. 6, the joint resin around the heating wire 10 starts to melt, 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 is sufficiently adhered to the pipe 3, the process in the period A3 starts. 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, consider the case where the pipe 3 is not sufficiently inserted into the joint 2 as shown in FIG. If the pipe 3 is insufficiently inserted as described above, a part of the heating wire 10 does not completely contact the pipe 3, so that the heat capacity and the thermal conductivity remain reduced. As a result, as shown by a two-dot chain line in FIG. Therefore, when the gradient of the temperature rise of the heating wire 10 is larger than the gradient of the temperature rise of the heating wire 10 stored in the memory 23 in advance, it is determined that the insertion of the pipe 3 into the joint 2 is incomplete. can do.

Accordingly, the electric fusion bonding apparatus 1 of the above embodiment
When the time rate of change of the temperature obtained by the time rate-of-change calculating unit 22 is equal to or greater than the specified value, the insertion shortage detecting unit 24 determines that the insertion of the pipe 3 into the joint 2 is incomplete. You can do it. In particular, in this embodiment, the period A
The time rate of change of temperature is determined from the data in
Since the insufficient insertion of the pipe 3 into the pipe 2 is monitored, the insufficient insertion can be checked at the final stage of the connection work between the joint 2 and the pipe 3.

As can be seen from FIG. 4, not the rate of change of the heating wire temperature with time but the heating wire 1 after a certain time after the start of energization.
Insufficient insertion of the pipe 3 can be detected from the zero temperature itself. However, when the temperature of the heating wire 10 is used,
It will be 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, since the time rate of change of the heating wire temperature is directly obtained from the resistance value of the heating wire 10, the time change rate of the heating wire 10 can be stably obtained. 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.

Further, 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 the 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.

If the pipe 3 is insufficiently inserted, the portion of the heating wire 10 not in contact with the pipe 3 becomes abnormally high in temperature, and the surrounding resin may emit smoke or fire. Therefore, in the period A3, the time when the heating line temperature data is obtained and the time rate of change of the heating line temperature is detected is earlier in the process of the period A3 when the joint resin does not emit smoke (when the heating line temperature is relatively low). Is preferred.

(Second and Third Embodiments) In the above-described embodiment, the resistance value is determined from the applied voltage and the energizing 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 for the pipe. Insufficient insertion is detected, but if the heating wires 10 are the same, the relationship between the resistance value and the heating wire temperature is fixed, so that the configuration in FIG. 2 can be simplified. For example,
The temperature calculating section 21 can directly determine the temperature of the heating wire from the applied voltage of the heating wire 10 and the supplied current. 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, it is possible to directly detect the insufficient insertion of the pipe 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 calculating unit 22 calculates the time change rate of the resistance value, and the insufficient insertion detection unit 24 detects the insufficient insertion of the pipe based on the time change rate of the resistance value.

(Fourth Embodiment) In the first embodiment,
Insufficient insertion of the pipe 3 was detected based on the time rate of change obtained from the heating line temperature data in the period A3. However, the time change rate of the heating line temperature obtained from the heating line temperature data in the period A1, and the heat generation in the period A2. The pipe 3 is inserted on the basis of the average of the three time-change rates of the heating wire temperature time change rate obtained from the wire temperature data and the heating wire temperature time change rate obtained from the heating wire temperature data in the period A3. The shortage may be detected. FIG. 11 shows an operation flow chart of the electrofusion apparatus of this embodiment. The circuit configuration of this embodiment is shown in FIG.
Since it is the same as the block diagram of FIG. Note that the process for obtaining one of the temperature and the resistance may be omitted by using the electric fusion bonding apparatus having the configuration shown in FIGS. 9 and 10.

The operation will be described with reference to the flowchart of FIG. When the start switch 7 is pressed (S51) 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 conduction current of the heating wire 10 (S52), and the resistance value of the heating wire 10 is determined from the conduction current and the applied voltage. (S53), the temperature of the heating wire is obtained from the resistance value (S54). The process of obtaining the temperature of the heating wire 10 (S52 to S54) is repeatedly executed until the temperature at which the detection is completed (S55). Here, the temperature at the end of detection is set to the heating line temperature relatively early in the period A3, and the heating line temperature data is sampled at two or more points in each of the periods A1, A2, and A3.

The data of the heating line temperature sampled in each of the periods A1 to A3 is used to calculate each of the periods A1 to A3.
The time rate of change of the heating wire temperature is calculated for each time (S56), and then the average value of the time rate of change in each of the periods A1 to A3 is calculated (S57). Next, the calculated average value of the time rate of change is compared with a specified value (S58). If the average value is smaller than the specified value, it is determined that the pipe 3 is completely inserted and the energization is continued, and the joint 2 and the pipe 3 are melted. Terminating connection (S5
9).

On the other hand, if the average value of the rate of change of the heating wire temperature with time is larger than the specified value, the heating wire 10
The power supply to the pipe 3 is stopped (S60), the buzzer 11 is sounded to notify the operator, and the display device 9 is informed of the insufficient insertion of the pipe 3 (S61).

As described above, the insertion shortage of the pipe 3 can be detected from the average value of the time rate of change of the heating wire temperature in the periods A1 to A3, but only the data in the period A3 as in the first embodiment. It is easier to detect from the following.

(Modification of the Fourth Embodiment) As in the fourth embodiment, the method of detecting the insufficient insertion of the pipe 3 from the average value of the time rate of change of the heating wire temperature in the periods A1, A2, A3 is as follows. , Can be simplified as follows.
That is, the temperature change rate (T2−T1) / Δ of the heating wire temperature is obtained from the temperature T1 at the start of energization (period A1) and the temperature T2 at the end of detection of the period A3 and the required time Δt between the two points.
In this method, t is obtained, and this value is used as the average value of the time rate of change of the heating wire temperature in the periods A1 to A3. In other words, this approximates the average value of the rate of change of the heating line temperature with time in the periods A1, A2, and A3 by, for example, the slope of a straight line connecting one point in the period A1 and one point in the period A3 in FIG. Is the way. According to this method, the number of points for obtaining the temperature can be reduced, and the processing can be simplified.

[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 where the pipe is insufficiently inserted into the joint.

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.

[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 Insertion shortage 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-7-164532 (JP, A) JP-A-7 -164530 (JP, A) JP-A-6-331087 (JP, A) JP-A-1-266393 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 65/34 F16L 13/00 F16L 47/02 B29L 23:00

Claims (5)

(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 means for detecting a current value flowing through the heating element, a means for detecting a voltage value applied to the heating element, and after the start of energization, the joint resin is melted and adhered to the pipe. 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 insufficient insertion of a pipe into a joint based on a time change rate of the resistance value. Wearing device. 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 means for detecting a current value flowing through the heating element, a means for detecting a voltage value applied to the heating element, and after the start of energization, the joint resin is melted and adhered to the pipe. Means for determining the temperature of the heating element from the current value flowing through the heating element and the applied voltage value, and detecting insufficient insertion of the pipe into the joint based on the time rate of change of the heating element temperature;
An electric fusion-bonding apparatus comprising: 3. An electric power supply 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 value of a current flowing through the heating element; a unit that detects a voltage value applied to the heating element; Obtain the resistance value, and from the start of energization to just before the start of melting of the joint,
From the start of melting of the joint until the joint resin adheres to the pipe,
Means for detecting insufficient insertion of the pipe into the joint based on the average value of the rate of change of the resistance value over time in each period after the melted joint resin has adhered to the pipe. 4. An electric power supply 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 value of a current flowing through the heating element; a unit that detects a voltage value applied to the heating element; Determine the temperature, from the start of energization to just before the start of melting of the joint, from the start of melting of the joint until the joint resin adheres to the pipe, the average of the time change rate of the temperature in each period after the melted joint resin adheres to the pipe. Means for detecting insufficient insertion of the pipe into the joint based on the value. 5. The system according to claim 1, wherein when the means for detecting insufficient insertion of the pipe detects insufficient insertion of the pipe into the joint, power supply to the heating element is stopped and an abnormality is notified. 5. The electric fusion bonding apparatus according to 2, 3, or 4.