JP2663379B2 - Electrofusion apparatus and energization control method thereof - 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 fusion welding apparatus and a method for controlling energization thereof. In particular, the present invention relates to an electric fusion welding apparatus for inserting an end of a pipe into a joint and applying heat to a heating element disposed on the inner peripheral surface of the joint to cause fusion to the end of the pipe (electrofusion). The present invention relates to a power supply control method. Further, the present invention relates to an electric fusion bonding apparatus using the method.

[0002]

2. Description of the Related Art An end of a thermoplastic resin pipe is inserted into a thermoplastic resin joint provided on an inner peripheral surface of a heating wire (electric resistance wire) wound in advance in a spiral shape, and an electric current flows through the heating wire. 2. Description of the Related Art An electric fusion bonding system that generates heat and melts and joins a joint surface between a joint and a pipe has been conventionally used.

In such an electric fusion welding apparatus, for example, a heating wire is energized to generate heat per unit time, thereby melting the resin of the joint and the pipe. When the heating wire reaches a predetermined power supply termination optimum temperature Ts, the power supply is stopped and the joint is allowed to cool. Conventionally, a joint and a pipe are generally joined by such a method.

[0004]

However, there is a demand for more perfect fusion of the joint and the pipe. In such a case, as shown in FIG. 9A, even after the original energization periods A1 to A3 have elapsed and the temperature of the heat generating wire has reached the energization end optimal temperature Ts, for a certain period A4, There is a method in which the power supply period is extended to continue the power supply to the heating wire, and the joint and the pipe are maintained at the power supply termination optimum temperature Ts.

[0005] For this reason, even if the heating wire is heated in the periods A1 to A3 to apply a heat quantity Q1 to the joints and pipes per unit time, the extension after reaching the optimum temperature Ts for ending the energization. In the period A4, the amount of heat generated per unit time added to the joint from the heating wire as shown in FIG. 9B so that the amount of heat applied per unit time to the joint is equal to the amount of heat released per unit time at the joint. It needs to be reduced to Q3.

Conventionally, the amount of heat radiation per unit time is obtained through experiments for each type of joint, and a value equal to the amount of heat radiation per unit time determined experimentally is stored in a memory in advance as a condition for energizing a heating wire. I was For this reason, it is necessary to collect a large amount of experimental data for each type of joint, and to experimentally determine the heat generation amount (or energization amount) per unit time for maintaining the joint at the optimal temperature Ts at which the energization ends. It took a lot of effort. When joints of different types and sizes are sold, it is necessary to rewrite the data in the memory each time.

Furthermore, even if the heat generating wire is heated under the energizing condition stored in the memory in advance due to the variation of the joint or the change of the environmental temperature, the heat generation amount per unit time of the heat generating wire and the heat radiation amount are not changed. An error occurs between them, in which case FIG.
As shown by a two-dot chain line in (a), there has been a problem that the maintenance temperature gradually deviates from the power-supply termination optimum temperature Ts. Especially,
If the temperature is lower than the optimum temperature Ts for terminating the energization as shown by the two-dot chain line a, sufficient effects cannot be obtained. Had deteriorated.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to detect the amount of heat released from the joint per unit time to maintain the temperature at the end of energization. The purpose of the present invention is to enable the temperature of the joint to be accurately controlled in an extended period of time.

[0009]

DISCLOSURE OF THE INVENTION According to a first aspect of the present invention, a power supply control method for an electric fusion splicer is provided in which a heating element disposed on an inner peripheral surface of a joint is energized to be inserted into the joint made of a synthetic resin and the joint. An electric power control method for an electric fusion welding apparatus for fusion-welding an end portion of a synthetic resin pipe, wherein the unit temperature applied to the joint before the temperature of the joint after melting of the joint reaches the optimal temperature at the end of energization is increased. The amount of heat per unit time is calculated from the time rate of change of each joint temperature before and after changing the amount of heat per unit time, and after the joint temperature reaches the optimal temperature at the end of energization, the unit It is characterized in that a heat quantity per unit time approximately equal to the heat release quantity per hour is applied to the joint.

The time rate of change of the temperature of the joint is determined by the amount of heat applied to the joint per unit time, the amount of heat released from the joint per unit time (including heat radiated through the pipe), and the heat capacity of the joint and the pipe. . Therefore, by changing the amount of heat applied to the joint per unit time and detecting the time rate of change of the joint temperature before and after the change, the amount of heat released from the joint per unit time can be automatically obtained. When the amount of heat released from the joint per unit time is obtained in this way, the amount of heat per unit time equal to the amount of heat released per unit time is applied to the joint to maintain the temperature of the joint at the optimal temperature at the end of energization at the end of the energization period. can do.

Therefore, according to the present invention, it is not necessary to experimentally determine the amount of heat radiation of the joint per unit time and store it in the memory. Therefore, it is not necessary to experimentally determine the heat radiation amount per unit time, and the experiment work for that purpose can be reduced.

Since there is no need for data on the amount of heat radiation per unit time for each joint, there is no restriction on the types of joints that can be handled. In particular, even when new joints of different types and sizes are sold, the memory is not required. Can be handled without rewriting the data.

Further, since the heat radiation amount per unit time of the joint is obtained from the actually measured value in the energization process, no error occurs due to variations in the joint and changes in the environmental temperature, etc., and the temperature of the joint is optimized with high accuracy. Temperature can be maintained.

According to the second aspect of the present invention, the electric fusion welding apparatus energizes a heating element disposed on the inner peripheral surface of the joint, thereby connecting the synthetic resin joint and the synthetic resin pipe inserted into the joint. An electric fusion welding apparatus for fusion-welding the 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; Before the temperature reaches the optimal temperature for turning off the power,
Before and after changing the amount of heat generated per unit time of the heating element, and before and after changing the amount of heat per unit time, the temperature of the heating element is determined from the current value flowing through the heating element and the applied voltage value, and the temperature change of the heating element over time Calculate the heat release per unit time from the rate,
Means for generating, from the heating element, an amount of heat per unit time substantially equal to the amount of heat radiation per unit time after the temperature of the joint has reached the optimum temperature for terminating the energization.

The electric fusion bonding apparatus according to the second aspect has the same operation and effect as the power supply control method for the electric fusion bonding apparatus according to the first aspect.

That is, 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 according to its temperature, the time rate of change of the heating element temperature (that is, the temperature of the joint) can be known from the time rate of change of the resistance value of the heating element.

Accordingly, in the electric fusion bonding apparatus according to the second aspect, the heat release amount per unit time of the joint is obtained based on the time change rate of the temperature obtained from the current flowing through the heating element and the applied voltage, Based on this, it is possible to determine the amount of heat per unit time for maintaining the heating element temperature at the optimal temperature at the end of energization.

In addition, in this electrofusion apparatus,
Since the temperature of the heating element is determined from the applied voltage of the heating element and the conduction current (that is, the resistance value), the temperature of the heating element, that is, the joint temperature can be directly determined, and the measurement error and variation can be reduced. Furthermore, since the temperature of the heating element is determined from the voltage applied to the heating element and the current supplied thereto, the heat capacity can be accurately detected irrespective of the output fluctuation of the electric fusion splicer.

[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.

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 heat radiation amount detector 24.

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 continuously obtained, and the time change rate calculating section 22 may differentiate the change in the temperature T to obtain the time change rate ΔT / Δt. It is sufficient to determine the temperatures T1 and T2 at two points and divide the temperature difference ΔT = T2−T1 by the time interval Δt.

As will be described later, the heat radiation amount detection unit 24 calculates the time change rate of the heating element temperature before and after the heat generation amount per unit time of the heating wire 10 is calculated by the time change rate calculation unit 22. The amount of heat radiation per unit time of the joint 2 (including that which radiates heat through the pipe 3) is detected based on the two time change rates.

The power control unit 17 is a part that performs the main function of the electric fusion welding apparatus 1. The power control unit 17 controls the power supply to the heating wire 10 of the joint 2 via the connection cable 5 by using the power obtained from the commercial power supply 25 as a source. Is what you do. The power control unit 17
According to a program stored in the memory 23 in advance,
The heating wire 10 is energized by a predetermined control method to cause the heating wire 10 to generate heat (see FIG. 3).

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

(Principle of fusion splicing operation of joint and pipe, principle of obtaining heat radiation amount per unit time of joint) Next, the operation of connecting the joint 2 and the pipe 3 by the electric fusion splicer 1 and the operation of the joint 2
The principle for automatically detecting the amount of heat radiation per unit time will be described. FIG. 3A is a diagram showing a temperature change of the heating wire 10 when energization of the heating wire 10 is started, and FIG. 3B is a heating value per unit time of the heating wire 10 (that is, a unit added to the joint 2). It is a figure which shows the change of the amount of heat per time). A period A1 indicates a period from the start of energization to immediately before the joint 2 starts to be melted, and 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. In A3, the melted resin adheres to the pipe 3,
A period in which the joint surfaces of the joint 2 and the pipe 3 are melted with each other is shown, and a period A4 is a period in which the joined joint 2 and the pipe 3 are maintained at the optimal temperature Ts at which the energization ends. Also,
4 to 6 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.

The operation from the start of energization of the heating wire 10 to the completion of joining and the state of the joint 2 and the pipe 3 will be described below with reference to FIGS. 3 (a) and 3 (b) and FIGS. When electric current is started to the heating wire 10 by the electric fusion bonding apparatus 1, as shown in FIG.
1 is generated and applied to the joint 2. Thus, the temperature of the heating wire 10 gradually increases as shown in FIG. The gradient of the temperature rise (time change rate) in each of the periods A1 to A3 is determined by the amount of heat applied to the joint 2 per unit time, the thermal conductivity between the heating wire 10 and the pipe 3, and the heat capacity of the joint 2 and the pipe 3. Things. 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. 4, the joint resin near the heating wire 10 is partially in contact with the pipe 3 but not in close contact. Therefore, the heat capacity and the heat conductivity are relatively small.
The slope of the temperature rise is relatively steep.

Next, in the period A2, the joint resin around the heating wire 10 starts to melt as shown in FIG. 5, 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.

Further, when the joint resin sufficiently adheres to the pipe 3, the process enters a period A3. As shown in FIG. 6, since the heat capacity increases when the joint resin is melted and adhered to the pipe 3, if the heat generation amount of the heating wire 10 per unit time is the same, the slope of the temperature rise in the period A3 is It becomes gentler than the slope of the temperature rise in A1. Here period A
At the end of 3, the heating wire temperature is equal to the predetermined end-of-power supply
Is reached. As shown in FIG.
32 is a period from when the temperature of the heating wire reaches a predetermined temperature Ts-ΔT1 (temperature for changing the heating condition) lower than the optimal temperature Ts for energization, to when the temperature reaches the optimal temperature Ts for energizing further.
In the period A31, the heating line temperature is changed to the temperature Ts−
This is a period from when a predetermined temperature Ts-ΔT2 (temperature at which detection is started) lower than ΔT1 is reached to when the temperature Ts-ΔT1 for changing the heating condition is reached, and both periods A31 and A32 are periods before the end of the period A3. It is located in. In the period A31, the heat generation amount of the heating line 10 per unit time is maintained at Q1, but when the heating line temperature reaches Ts-ΔT1 and the period A32 starts, as shown in FIG. 10
The heat value per unit time changes to Q2. The value of the heat quantity Q2 per unit time may be smaller or larger than Q1. Then, in the period A31,
The time rate of change of the heating wire temperature when the heating value of the heating wire 10 per unit time is Q1 is obtained. In the period amount A32, the heating wire temperature when the heating value of the heating wire 10 per unit time is Q2. Is determined over time.

The heat radiation amount detection unit 24 obtains the heat radiation amount per unit time of the joint 2 from the time change rate of each heating wire temperature in the period A31 and the period A32. Specifically, the time change rate of the heating wire temperature in the period A31 is κ1,
The heat value of the heating wire 10 per unit time at 31 is Q1
In addition, the time change rate of the heating wire temperature in the period A32 is κ2, the heat generation amount of the heating wire 10 per unit time in the period A32 is Q2, the heat release amount per unit time from the joint 2 is D, the joint 2 and the pipe Assuming that the heat capacity of No. 3 is C, there is the following relationship between them. κ1 = (Q1-D) / C... κ2 = (Q2-D) / C where κ1 and κ2 are detected by the time change rate detecting unit 22, and the heat values Q1 and Q2 per unit time are determined in advance. By solving the equations and the equations as simultaneous equations, the heat release amount D per unit time and the heat capacity C
Can be requested.

The temperature of the heating wire 10 is the optimum temperature Ts at which the energization ends.
When the temperature reaches a temperature at which the resin of the joint 2 and the resin of the pipe 3 are sufficiently fused, the heat radiation amount detection unit 24
And the heat radiation amount D of the pipe 3 is detected so that the heat generation amount Q3 of the heating wire 10 per unit time is equal to the heat radiation amount D per unit time (that is, Q3 = D...).
The amount of electricity to the heating wire 10 is determined. Then, extension period A
In 4, the heat generating wire 10 is heated by the heat amount Q3 equal to the heat radiation amount D per unit time, so that the heat generating wire temperature can be kept at a constant value (the optimal temperature Ts for ending the energization). Thereafter, the power supply to the heating wire 10 is terminated, and the joint 2 and the pipe 3
Is allowed to cool to near ambient temperature.

Strictly speaking, the heat radiation amount D per unit time is a function of the temperature, and the heat radiation amount D per unit time in the above equation and the equation needs to be corrected because the temperature is different. In addition, it is necessary to use the heat release amount D in the equation corrected to a value at the power supply end optimum temperature Ts. However, in a linear approximation, these heat radiation amounts D may be treated as equal values.

(Fusing Method) FIG. 7 shows an electric welding device 1 for connecting the joint 2 and the pipe 3 according to the above principle.
It is a flowchart explaining the operation | movement procedure of. First, the start switch 7 is pressed (S31) to start energizing the heating wire 10. When the energization is started, the power control unit 17 energizes the heating wire 10 so that the amount of heat generated per unit time becomes a constant value Q1 (FIG. 3B). Then, after the current and voltage of the heating wire 10 are stabilized, the current detection unit 19 detects the value of the current flowing through the heating wire 10 and the voltage detection unit 18 detects the voltage applied to the heating wire 10. (S3
2) The resistance value calculating section 20 determines the resistance value of the heating wire 10 from the detected values of the supplied current and the applied voltage (S33), and then converts the resistance value of the heating wire 10 to the heating wire temperature by the temperature calculating section 21. (S34). While repeatedly detecting the heating line temperature (S32 to S34), the process waits until the heating line temperature becomes the detection start temperature Ts-ΔT2 during the period A3 (S35). This detection start temperature Ts-ΔT2 is equal to the period A
3 is set to an appropriate temperature lower than the temperature Ts-ΔT1 of the heating condition change (that is, ΔT2> ΔT
1: see FIG. 3 (a)).

When the temperature of the heating wire reaches the detection start temperature Ts-ΔT2, the current detecting unit 19 detects the value of the current flowing through the heating wire 10 and the voltage detecting unit 18 detects the voltage applied to the heating wire 10. (S36), the resistance value calculating section 20 obtains the resistance value of the heating wire 10 from the detected values of the supplied current and the applied voltage (S37), and then the temperature calculation section 21 converts the resistance value of the heating wire 10 to the heating wire temperature. It is converted (S38). In this way, until the heating wire temperature reaches the heating condition change temperature Ts-ΔT1 (S39), the heating wire temperature is repeatedly detected (S36 to S38).

The heating wire temperature is the temperature Ts-Δ at which the heating conditions are changed.
When the temperature reaches T1, the time rate-of-change calculating unit 22 calculates the heating wire temperature rise amount obtained during the period between the detection start temperature Ts-ΔT2 and the heating condition change temperature Ts-ΔT1, and the energization time during that, The time rate of change of the heating wire temperature in the period A31 is obtained (S40). Next, the power control unit 17 changes the heating condition of the joint 2, that is, the amount of heat generated per unit time of the heating wire to Q2 (S41).

After the heating condition of the joint 2 is changed, the value of the current flowing through the heating wire 10 is further detected by the current detection unit 19, and the voltage applied to the heating wire 10 is detected by the voltage detection unit 18 (S42). ), The resistance value calculating section 20 determines the resistance value of the heating wire 10 from the detected values of the supplied current and the applied voltage (S43), and then converts the resistance value of the heating wire 10 to the heating wire temperature by the temperature calculating section 21 (S43). S44). In this way, the heating wire temperature is repeatedly detected until the heating wire temperature reaches the power supply termination optimum temperature Ts (S45) (S42 to S42).
S44).

When the temperature of the heating wire reaches the optimum temperature Ts for terminating the energization, the time rate-of-change calculating unit 22 determines the heat generation in the time period A32 from the amount of increase in the heating wire temperature in the time period A32 after the change of the heating condition and the energizing time during that time. The time rate of change of the linear temperature is determined (S46). Next, the heat radiation amount detection unit 24 detects the heat radiation amount D per unit time of the joint 2 as described above from the time change rate of the heating wire temperature in the period A31 and the time change rate of the heating wire temperature in the period A32. And heating wire 1
The amount of power to the heating wire 10 is obtained and automatically set in the power control unit 17 so that the heat generation amount Q3 per unit time of 0 becomes equal to the detected heat release amount D per unit time (S4).
7). The power control unit 17 changes the heating condition of the heating wire 10 according to the set energization amount (S48), and supplies a current of the set energization amount to the heating wire 10 for a predetermined time (period A4) ( S49) Generate a heat quantity of Q3 per unit time from the heating wire 10. As a result, the heating wire temperature, that is, the temperature of the joint 2 is maintained at the power-supply end optimal temperature Ts during the period A4. When the period A4 has elapsed, the energization ends (S50).

In the present invention, as described above, the period A3
, The amount of heat released per unit time of the joint 2 is detected from the time change rate of the heating wire temperature before and after the heating condition. Based on the detected value of the amount D of heat released per unit time, the joint 2 The temperature is maintained at the power supply end optimum temperature Ts. Therefore, it is not necessary to previously store the data of the heat radiation amount per unit time in the memory for each joint, and in particular, in the period A4, the condition for maintaining the temperature of the joint 2 at the energization termination optimum temperature Ts is determined. Complex experiments can be eliminated. In addition, it can cope with the case of a new joint.

In addition, since the heat radiation amount per unit time of the joint 2 is obtained by using the fusion bonding process of the joint 2 and the pipe 3, the process time is not lengthened and the working efficiency is not reduced.

Further, according to 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 temperature can be obtained stably. For example, to measure the temperature of the heating wire 10,
When a temperature measuring device such as a thermocouple or a thermistor is brought into contact with the heating wire 10, the measurement result also varies due to the variation in the thermal resistance (changes due to the thickness of the resin or the like) between the heating wire 10 and the temperature measuring device. Unstable and unstable. In contrast,
If it is determined from the resistance value of the heating wire 10, the temperature of the heating wire can be detected stably. If the heating wire 10 having a large temperature coefficient of resistance 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.

(Other 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 detected. If 10 is 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. In other words, the temperature calculating section 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.
The resistance value calculation unit 20 can be omitted, and the operation flow can be simplified accordingly.

[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 (a) is a diagram showing the relationship between the energizing time and the temperature of the heating wire (resistance value of the heating wire) when the heating wire of the joint is heated using the above electric fusion bonding apparatus, and (b). FIG. 3 is a diagram showing a change in the amount of heat per unit time applied to a joint and a pipe.

FIG. 4 is a cross-sectional view showing a state of a joint and a pipe during a period A1.

FIG. 5 is a cross-sectional view showing a state of a joint and a pipe in a period A2.

FIG. 6 is a cross-sectional view illustrating a state of a joint and a pipe in a period A3.

FIG. 7 is an operation flowchart of the above electric fusion bonding apparatus.

FIG. 8 is a block diagram showing a circuit configuration of an electrofusion apparatus according to another embodiment of the present invention.

FIG. 9 (a) is a diagram showing the relationship between the energization time and the temperature of the heating wire (resistance value of the heating wire) when heating the heating wire of the joint using the conventional electric fusion bonding apparatus, and (b). FIG. 3 is a diagram showing a change in the amount of heat per unit time applied to a joint and a pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 Joint 3 Pipe 4 Electric fusion bonding apparatus main body 10 Heating wire 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 Heat release amount detection unit

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takuhide Nakayama 3-9-20 Togoshi, Shinagawa-ku, Tokyo Hirata Kiko Co., Ltd. (56) References JP-A-8-270870 (JP, A) JP-A-8 -99358 (JP, A) JP-A-7-16930 (JP, A) JP-A-8-52804 (JP, A)

Claims (2)

(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. A method of controlling the power supply of a fusion splicer, comprising: changing the amount of heat per unit time applied to the joint before and after changing the amount of heat per unit time before the temperature of the joint after melting of the joint reaches an optimum temperature at which the energization ends. The amount of heat radiation per unit time is determined from the time change rate of each joint temperature, and after the temperature of the joint reaches the optimal temperature at the end of energization, the amount of heat per unit time approximately equal to the amount of heat radiation per unit time is applied to the joint. A current supply control method for an electric fusion welding apparatus, characterized by adding. 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, means for detecting a current value flowing through the heating element; means for detecting a voltage value applied to the heating element; Before and after changing the amount of heat generated per unit time of the heating element, before and after changing the amount of heat per unit time, the temperature of the heating element is obtained from the current value flowing through the heating element and the applied voltage value. Means for determining the amount of heat radiation per unit time from the rate of change, and after the temperature of the joint has reached the optimum temperature for terminating energization, generating a heat amount per unit time from the heating element substantially equal to the heat radiation amount per unit time; Characterized by having Electric welding equipment.