JP2828425B2 - How to connect plastic tubes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a plastic pipe made of polyethylene or the like into a plastic joint in which a heating wire is embedded in an inner peripheral portion and melting and connecting the joint and the pipe.

[0002]

2. Description of the Related Art Conventionally, there has been disclosed a control method in which a surface temperature of a joint member is measured by a temperature sensor before energization is started, and the amount of electric power supplied to the heating wire of the joint member is controlled with time based on the measured temperature. ing. This temperature sensor is incorporated in the connection terminal to the joint member, and the temperature of the joint is measured by the sensor at the same time as the connection terminal is connected to the joint member.

[0003]

In the above-mentioned prior art, the temperature of the joint rises during the fusion operation with the pipe by supplying power to the heating wire of the joint, so that the temperature sensor becomes hot. Become. For this reason, when performing the next fusion work continuously after the fusion work is completed, the heat from the previous fusion splicing remains in the temperature sensor, and the temperature sensor does not drop to the ambient temperature and is still hot. In this state, the temperature of the next newly connected joint may be measured. In this case, the correct initial temperature of the joint could not be measured, and the wrong temperature higher than the actual temperature was judged as the initial temperature of the joint, and based on this incorrect initial temperature, the joint and pipe were fused from the control power supply to the heating wire of the joint. There is a problem in that the conduction control of the welding is performed to cause poor fusion such as insufficient fusion or excessive fusion.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem that the energization control is performed by erroneous initial temperature measurement to cause poor fusion, that the initial temperature of the joint is always correctly detected, and that the energization control is performed based on the detected value. An object of the present invention is to provide a method of connecting a plastic pipe so that a correct welding operation can be performed.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is to insert a plastic pipe to be connected to a plastic joint in which a heating wire is embedded, and to fuse the joint and the plastic pipe by energizing the heating wire. in the connection method, prior to energizing Previous Symbol heating wire, to measure the temperature of the joint by the temperature sensor, determines whether or not a large change in the measured temperature, the temperature change preset value It is characterized in that the temperature at which the temperature becomes below is detected as the initial temperature of the joint, and the control of energization to the heating wire is performed based on the initial temperature .

[0006]

According to the present invention, a change in the temperature of the joint measured by the temperature sensor is monitored before the energization of the heating wire is started, and the initial temperature of the joint is detected based on the temperature change. The temperature of the sensor in a state where the temperature change is small is a temperature at which the sensor heated during the previous fusion work is cooled to the same temperature as the temperature of the joint to be connected this time. That is, it indicates the temperature in the state where the influence of the heat at the time of the previous fusion is eliminated, and this is detected as the initial temperature of the joint. Because of this, the thermal effect of the heated sensor at the time of the previous fusion is automatically removed, so even if the fusion work is performed continuously,
The initial temperature of the joint to be subsequently connected is always correctly detected, and the control of energization to the joint heating wire can be correctly performed based on the correct initial temperature detection value. Therefore, the problem of poor fusion such as insufficient fusion or excessive fusion between the joint and the pipe due to an incorrect initial temperature detection value is solved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In FIG.
A heating wire 4 to be heated by energization is buried in an inner peripheral surface in a spirally wound state. Connector pins 7, 7 are connected to both ends of the heating wire 4, and connectors 6, 6 of the controller 5 are connected to the connector pins 7, 7. Electric current is applied from the controller 5 to the heating wire 4 to cause the heating wire 4 to generate heat, and the heat generated by the heating wire fuses with the plastic pipes 1 and 1 mounted in the joint body 2.

Reference numeral 3 denotes a temperature sensor formed of, for example, a thermocouple, which is inserted into a temperature measurement concave hole 2a provided in the joint body 2 to measure the temperature of the bottom surface of the concave hole. The sensor 3 measures the temperature of the joint body 2 before the start of energization, and sets the energization completion temperature at which energization is completed in the controller 5 based on the initial temperature measured before the energization starts. The energization is terminated when the temperature of the main body reaches the set energization completion temperature.

FIG. 2 is a diagram showing the relationship between the outside air temperature and the energization time. If the set energization completion temperature is fixed, the energization time until the energization completion temperature differs depending on the outside air temperature. An optimal energization completion temperature is set according to the outside air temperature, and energization is stopped in the controller 5 in a control method in which energization is stopped when the set energization completion temperature is reached. Further, in the present embodiment, as shown in FIG. 3, even if the temperature of one sensor 3 inserted into the concave hole 2a of the joint body does not reach the set temperature, if the temperature of the other sensor 3 reaches the set temperature, power is supplied. Stopped. By this method, one sensor 3
Even if there is a measurement failure due to an insertion error or the like into the concave hole 2a of the joint body, correct temperature measurement is performed by the other sensor, and correct temperature measurement is performed.

Next, the state of the energization control will be described with reference to the flowcharts of FIGS. First, in Fig. 4, the power is turned on.
Then, the entire controller 5 is reset, the time display is reset to 0, and the connector mounting lamp of the controller is turned on. And two connectors 6, 6
Is connected to the connector pins 7 of the joint body 2, the connector mounting lamp is turned off and the connector connection lamp is turned on. Next, when the power button is pressed, the power lamp starts blinking. In this state, power is not yet supplied, and the operation state of the sensor 3 is checked. If the sensor 3 is disconnected, an abnormal lamp is lit and a buzzer sounds to notify the abnormality.

If the sensor 3 has not been disconnected, a change in temperature as to whether the sensor is accurately measuring the temperature of the joint body 2 is checked in step (a). Here, the sensor 3 itself waits until the influence of the heat received in the previous fusion work disappears and the temperature change becomes small. That is, when the temperature change is large, the process returns in the loop (b), and the determination (a) of the presence or absence of the sensor disconnection and the temperature change is repeated. When the temperature change of the sensor 3 becomes small, the temperature of the sensor in the state where the temperature change becomes small in step (c) is detected as the initial temperature of the joint. The energization completion temperature is set in step (d) based on the initial temperature, and the energization completion temperature is stored in the memory.

Subsequently, a predetermined voltage is output from the controller 5 to the heating wire 4 via the connector 6, the energization time starts counting, the energization lamp changes from blinking to lighting, and a buzzer for informing the energization state is produced with a low tone. Sound. Then, sensor 3 disconnection, heating wire 4 short-circuit, heating wire 4
The presence / absence of a voltage abnormality output to the controller and the presence / absence of a temperature rise abnormality of the joint body 2 are checked. If there is any abnormality, the abnormality lamp lights up,
A buzzer sounds to inform you of the abnormality.

If there is no abnormality and the reset button is not pressed, the above abnormality check is repeated until the energization completion set temperature set based on the initial temperature detection value of the joint is reached. When the temperature reaches the temperature, the current supply to the heating wire 4 is stopped. Next, as shown in FIG. 5, the circuit in the controller 5 is cut off, the energizing lamp is turned off, the buzzer stops sounding, and the cooling lamp indicating that cooling is in progress is turned on. When a predetermined cooling time 55 seconds elapses according to the joint, the cooling lamp is turned off, a buzzer indicating the completion of cooling sounds twice with a high tone, and the connector removal lamp is turned on.
When the connector is removed from the fitting, the fitting removal lamp goes off and the connection lamp goes off, thereby terminating the fusing operation.

The present invention is controlled as described above to determine whether the temperature of the sensor 3 is accurately measuring the temperature of the joint main body 2 by eliminating the influence of the heat received by the previous welding operation on the sensor itself. That is, the initial temperature of the joint body is detected by determining in step (a) until the temperature change becomes small. Therefore, even if the welding operation is performed continuously, the correct initial temperature of the joint body is detected without being affected by the heat received in the previous welding operation, and the heating wire of the joint is determined based on the correct detected initial temperature value. In this way, the controller can be energized, and correct fusion can be performed.

[0015]

As described above, according to the present invention, even if the welding operation is continuously performed using the temperature sensor heated during the previous welding operation, the thermal influence of the sensor received at the previous welding operation is eliminated. Then, the initial temperature of the joint to be connected next is always detected correctly. Since the energization control to the joint heating wire is performed based on the correct initial temperature detection value, correct fusion splicing without defective fusion can be performed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state of connection with a plastic tube according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a temperature sensor based on a difference in outside air temperature and an energization time.

FIG. 3 is a diagram illustrating a relationship between a sensor temperature and an energization time when one of the temperature sensors has an abnormality.

FIG. 4 is a flowchart showing control of energization of a joint by a controller.

FIG. 5 is a flowchart showing control of energization of a joint by the controller following FIG. 4;

FIG. 6 is a cross-sectional view illustrating a state of connection with a plastic tube for explaining a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plastic pipe 2 Joint body 2a Concave hole 3 Temperature sensor 4 Heating wire 5 Controller 6 Connector 7 Connector pin

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-203991 (JP, A) JP-A-62-73129 (JP, A) JP-A-63-311131 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) F16L 47/02 F16L 47/06

Claims (1)

(57) [Claims] 1. A plastic joint in which a heating wire is embedded.
Insert the plastic tube to be connected, and
A plastic that fuses the joint and the plastic tube by electricity
In the method of connecting the stick pipe, before energizing the heating wire, the temperature sensor is used to connect the joint.
Measure the temperature and see if the change in the measured temperature is large
Judge that the temperature change is below a preset value.
Is detected as the initial temperature of the joint.
Control the energization of the heating wire based on the initial temperature of the heating wire
A method for connecting a plastic tube, characterized by comprising: