JP2002115791A - Electric fusion joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate necessity to correct weld time according to temperature. SOLUTION: In an electric fusion joint 2 having an electric resistance wire on the internal surface side thereof, and controlling weld time by reading a bar code 1 attached thereto, into which weld time has been inputted, such an electric resistance wire that the average temperature coefficient (10-6/K) between 20 deg.C and 100 deg.C of volume resistivity is 1,000 or above is used as the electric resistance wire 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrofusion joint made of a thermoplastic resin having an electric resistance wire inside for melting and joining thermoplastic resin tubes to each other.

[0002]

2. Description of the Related Art Conventionally, a synthetic resin pipe made of a material such as polyethylene or polybutene has been fused and joined by an electrofusion joint made of a thermoplastic resin having an electric resistance wire inside. ing. As a method for controlling the energizing time when the synthetic resin pipes are fusion-bonded to each other by the electric fusion joint, there is an energizing time control method of a resistance identification method disclosed in Japanese Patent Publication No. 3-27014. In this energization time control method, a current is applied to an identification resistor embedded separately from the electric resistance wire inside the electric fusion joint, or a voltage is applied to grasp the electric resistance value. The energization time is determined from the relationship between the type (type of socket and cap, etc.) and the standard energization time set for each bore (nominal diameter of the connection port), and the energization is automatically performed for this time. I have. Further, as another energization time control method, a bar code disclosed in Japanese Patent Publication No. 7-45185 is disclosed.
There is an energization time control method of the power supply type. In this energization time control method, a bar code in which an energization time appropriate for each joint is input in advance is attached to the joint body, and the bar code is energized with a bar code reader or bar code. -Scanner-
By reading the information of energization control including energization time,
The energization time is automatically determined.

[0003] The energy required for fusion depends on the temperature of the joint. The lower the temperature, the more energy is required, and the higher the temperature, the less the energy. Therefore, in the above-described control method in the prior art, the outside air temperature (environmental temperature) detected by the temperature sensor installed in the control device is input to the fusion sequence monitoring unit as outside air correction information, and the outside air correction is performed. From the information and the standard applied voltage and the standard energizing time, the energizing time to be supplied is varied,
The supplied energy is corrected by the outside air temperature.

[0004] However, if the temperature sensor is installed not in the joint but in the control device, the control device is bare in the construction site in the hot summer or in a cold area under strong wind, so that the temperature sensor cannot be used. An extreme temperature difference occurs between the temperature of the installed control device and the actual temperature of the joint, and an extremely incorrect temperature correction is performed.

A method disclosed in Japanese Patent Application Laid-Open No. 2000-55280 has been proposed in order to solve such a fusion defect due to the temperature correction. This energization time control method is a pipe joint made of a thermoplastic resin provided with a heating wire for heating on the inner peripheral surface,
When a pipe made of a thermoplastic resin inserted into the inner peripheral surface of the pipe joint is fusion-spliced by supplying predetermined electric power to the heating wire and electrically energizing and heating, an environment before energizing the heating wire is required. The temperature is measured, and in the power supply control method for the electric fusion joint, which sets the power supply time based on the environmental temperature, the standard power supply time at the upper environmental temperature does not fall below the lower power supply time at the lower environmental temperature, and at the lower environmental temperature. The standard energizing time does not exceed the upper limit energizing time at the upper limit environmental temperature.

FIG. 3 is a block diagram of an electrofusion control device used in the above-described energization time control method. FIG. 4 is a graph showing the relationship between the environmental temperature of the electrofusion joint and the energization time in this energization time control method. It is. A bar code 31 is attached to the electrofusion joint 32 (hereinafter simply referred to as a joint) by a label or a tag. The bar code 31 is input with coded information of energization control parameters supplied to the heating wire of the joint 32. A coil-shaped heating wire 33 is embedded in the joint 32. Both ends of the heating wire 33 are connected to terminal pins 34, and connected pipes 35, 35 extending from the left and right receptacles of the joint 32 to the approximate center are inserted. In order to energize the heating wire 33 of the joint 32 and normally weld and connect the joint 33 and the connected pipes 35, 35,
An electric fusion control device 40 is provided. The electric fusion control device 40 includes a power supply unit 41, an arithmetic control unit 42, and a storage unit 4.
3, a reading means interface 44, an output section 45, a display section 46, and a reading means 47. In order to measure the environmental temperature, a temperature sensor 49 is attached to the electrofusion control device 40 via a temperature sensor interface 48. The power supply unit 41 is connected to the arithmetic control unit 42 and the output unit 45.
The terminal 32 is connected to the terminal pin 34 by connectors 51 and 51 provided on the joint 32 through the connector 0.

When the power supply cord 52 is connected to a power supply, an appropriate current is supplied to the joint 32 for a predetermined time. As a result, the heating wire 33 generates heat, and the inner surface of the joint 32 made of a thermoplastic resin such as polyethylene and the outer surfaces of the connected pipes 35, 35 made of the same thermoplastic resin such as polyethylene are melted and joined. Is done.

The arithmetic control unit 42 is constituted by a microprocessor, is connected to the storage unit 43 to exchange information, determines whether or not the connection is possible, and sends an energizing operation command to the output unit 45. The storage unit 43 is configured to record energization control data, fusion history data, and the like. Specifically, the arithmetic control unit 42 includes a reading unit interface.
Bar read from reading means 47 through face 44
The data of the energization control parameter of the code is fetched.
Further, the arithmetic and control unit 42 has a temperature sensor 49 via a temperature sensor interface 48 in addition to the power supply control data.
Environmental temperature data from the computer.

When the temperature of the power-on time of the joint 32 is corrected by using the electric fusion control device 40, it is performed as follows. FIG. 4 is a graph showing the relationship between the environmental temperature and the energizing time, wherein a straight line S indicates the relationship between the environmental temperature and the standard energizing time, and a straight line U indicates the relationship between the environmental temperature and the upper limit energizing time.
A straight line D indicates the relationship between the environmental temperature and the lower limit energizing time. The relationship between the environmental temperature of the joint 32 and the energizing time is determined by the standard energizing time (α point) at the upper limit environmental temperature (normally 40 ° C.).
Does not fall below the lower limit energization time (β point) at the lower limit environmental temperature (normally −5 ° C.), and the lower limit environmental temperature (normally −5 ° C.)
C.) so that the standard energization time (γ point) does not exceed the upper limit energization time (δ point) at the upper limit environmental temperature (normally 40 ° C.).

With the joint 32 having such characteristics, even if the electric fusion control device 40 is placed outdoors under the scorching sun, that is, even if the environmental temperature becomes high (point a '), the environmental temperature (a The standard energization time (point b ') corrected by the correction formula from the point') does not fall below the lower limit energization time (point d ') at the actual joint temperature (point c'). As a result, the energy required for normal fusion splicing is supplied to the heating wire within the range between the straight line U and the straight line D, so that the energization time is shortened and a defect due to insufficient fusion does not occur.

On the other hand, even if the electric fusion control device 40 is placed outdoors in a cold region, that is, even if the environmental temperature becomes low (point e '), it is corrected by a correction formula from this environmental temperature (point e'). The standard energizing time (point f ') is the actual joint temperature (g'
At the point (h '). As a result, the energy required for normal fusion splicing is supplied to the heating wire within the range between the straight line U and the straight line D.
There is no risk of deterioration of the resin or short-circuiting of the heating wire caused by over-fusion.

[0012]

However, the above-mentioned conventional method for controlling the energization time of the electrofusion joint has the following problems. A specific method for providing the electrofusion joint with characteristics that the standard energizing time at the upper limit environmental temperature does not fall below the lower limit energizing time at the lower limit environmental temperature and the standard energizing time at the lower limit environmental temperature does not exceed the upper limit energizing time at the upper limit environmental temperature. Method is not disclosed, and the feasibility is poor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and is capable of melting a joint and a connected pipe without changing the energization time even if the environmental temperature changes. It is an object of the present invention to provide an electrofusion joint that can appropriately perform the above.

[0014]

An electric fusion joint according to the present invention is provided with an electric resistance wire on the inner surface side of the joint, and when the electric resistance wire is energized to generate heat to melt-join the joint and the pipe. Is the bar code that is the input of the energization time attached to the joint.
In the electrofusion joint of the type in which the energization time is controlled by reading the electric resistance, the electric resistance wire has a volume resistivity of 20%.
The average temperature coefficient (10 ^-6 / K) between ~ 100 ° C is 1000
The above-described electric resistance wire is used.

The electric resistance wire having an average temperature coefficient (10 ⁻⁶ / K) of 1000 or more of the volume resistivity between 20 ° C. and 100 ° C. may be a copper nickel resistance wire, a nickel aluminum resistance wire, a nickel aluminum resistance wire, or the like. A resistance wire or a copper resistance wire is used.

When the actual temperature of the joint changes, as shown by the solid line A in FIG. 2, the amount of welding energy required for welding the joint must be small at high temperatures and large at low temperatures. On the other hand, the fusion energy -En generated when the voltage is V, the resistance value is R, and the energizing time is t is expressed by the following equation (1) in the case of constant voltage control.

En = V ² · t / R (1) That is, if the voltage V and the conduction time t are the same, the smaller the resistance R, the larger the fusion energy En and the larger the resistance R. The fusion energy En decreases. The electrical resistance R of a metal is represented by the following equation (2), where the length of the metal is lm and the sectional area is am ² .

[0018] referred to as R = ρ · l / a ( Ω) ............ (2) (2) ρ in equation volume resistivity (unit: Ω · m), and it at 100 ° C. and [rho _100, 20 Assuming that at ℃ is ρ ₂₀ , α ₂₀ represented by the following equation (3),
₁₀₀ is called an average temperature coefficient between 20 ° C. and 100 ° C. of the volume resistivity.

Α ₂₀ , ₁₀₀ = (ρ ₁₀₀ −ρ ₂₀ ) / 80ρ ₂₀ (3) As is apparent from the equations (2) and (3), the volume resistivity between 20 ° C. and 100 ° C. Is larger, the difference between the resistance R at high temperature and the resistance R at low temperature is larger, and the smaller the average temperature coefficient is, the higher the resistance R at high temperature and the resistance R at low temperature are.
Is smaller.

Conventionally, a nickel chrome wire or a nickel copper wire having a nickel content of about 15% by weight is used as the heating wire of the electrofusion joint, so that the volume resistivity is 20 to 100%. Average temperature coefficient between ° C is 0 or 2
The resistance R is almost the same at low and high temperatures. Therefore, if the energization time t is constant, the generated fusion energy En does not change between high and low temperatures, as indicated by the dotted line B in FIG. Failure to do so results in defects due to insufficient fusion, and the required fusion energy at high temperatures
Since the above fusion energy is generated, there is a possibility that the resin may be degraded due to overfusion and the heating wire may be short-circuited.
For this reason, conventionally, the energization time is shortened at high temperatures, and the energization time is lengthened at low temperatures.

However, in the electric fusion joint of the present invention, the electric resistance wire has a volume resistivity of 20 to 100 ° C.
Since an electric resistance line having an average temperature coefficient of 1000 or more is used, the resistance R of the electric resistance line is small at low temperatures and large at high temperatures. Therefore, the generated fusion energy En is close to the required fusion energy indicated by the solid line regardless of the temperature, as shown by the broken line C in FIG. Therefore, it is not necessary to control the energization time depending on the temperature.

The electric resistance line has a volume resistivity of 20.
The reason for using an electric resistance wire having an average temperature coefficient of 1000 or more between 100 ° C. and 1000 ° C. is that if the average temperature coefficient is less than 1000, it becomes necessary to control the energization time depending on the temperature. Examples of the electric resistance wire corresponding to the electric resistance wire having an average temperature coefficient between 20 to 100 ° C. of the volume resistivity of 1000 or more include general-purpose copper-nickel resistance wires specified in JIS C 2532 (1990), and general-purpose copper nickel resistance wires. There are nickel aluminum resistance wire, general nickel resistance wire and general copper resistance wire.

[0023]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of the electrofusion joint of the present invention. A bar code 1 is attached to the electrofusion joint 2 (hereinafter simply referred to as a joint) by a label or a tag. The bar code 1 is input with coded information of energization control parameters supplied to the heating wire of the joint 2. A coil-shaped heating wire 3 is embedded in the joint 2. Both ends of the heating wire 3 are connected to terminal pins 4, and connected pipes 5, 5 from the left and right receptacles of the joint 2 to the approximate center are inserted. Electric fusion control device 1
0 denotes a power supply unit 11, an operation control unit 12, a storage unit 13, a reading unit interface 14, an output unit 15, a display unit 16,
A reading unit 17 is provided. The power supply unit 11 is connected to the arithmetic and control unit 12 and the output unit 15, and the output unit 15 is connected to the connector 2 provided on the joint 2 via cables 20 and 20.
The terminals 1 and 21 are connected to the terminal pins 4. When the power supply cord 22 is connected to the power supply, an appropriate current is supplied to the joint 2 for a predetermined time. As a result, the heating wire 3 generates heat and the joint 2 made of a thermoplastic resin such as polyethylene.
And the outer surfaces of the connected pipes 5 and 5 made of the same thermoplastic resin such as polyethylene, and are fused and joined. The arithmetic control unit 12 is configured by a microprocessor, is connected to the storage unit 13 to exchange information, determines whether or not the connection is possible, and can send an energization operation command to the output unit 15. The storage unit 13 records energization control data, fusion history data, and the like. More specifically, the arithmetic and control unit 12 transmits data (a manufacturer name, a name of a power supply control parameter) of a bar code read from the reading means 17 via the reading means interface 14. Item type, nominal diameter, serial number, design thickness, resin material) are imported.

As the heating wire 3 of the above-described electrofusion joint of the present invention, a copper wire having a copper content of 99% by weight and an average temperature coefficient of about 3900 is used. Then, this copper wire is wound around a bobbin in advance, and a thermoplastic resin is injection-molded outside the bobbin to form the joint 2. Therefore, electricity is supplied to the heating wire 3 of the electrofusion joint of the present invention,
When the joint 2 and the connected pipes 5 and 5 are fused and joined by fusion, when the temperature of the joint 2 is low, the resistance of the heating wire 3 is small, so that the generated fusion energy is large and the temperature of the joint 2 is low. When the temperature is high, the resistance of the heating wire 3 is large, so that the generated fusion energy is small, and even if the energization time is constant, the generated fusion energy becomes the energy required for fusion regardless of the temperature. This is proportional, and the energization time is not controlled by the temperature.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of the present invention, an insertion type electrofusion joint having a nominal diameter of 75 using a copper wire having an average temperature coefficient of 3900 as a resistance wire was used to determine the state of fusion between a pipe inserted into the joint. investigated. The temperature of the joint at the start of fusion is selected to be 40 ° C or -5 ° C, and the current is applied for 150 seconds at each temperature. The condition was observed. Judgment of the occurrence of over-fusing is made by monitoring the current value and checking whether there is an instantaneous increase in the current value because the resistance wire is short-circuited when the synthetic resin is melted too much. Judgment of the occurrence of shortage of clothes is made according to JIS K 6775-3.
The test was performed according to the pilling test method specified in the above. As a result, no excessive fusion was observed at 40 ° C., the peeling rate at −5 ° C. was 10%, and insufficient fusion was not observed.

On the other hand, in the case of the conventional electrofusion joint using the copper-nickel GCN having an average temperature coefficient of 200 for the resistance wire, the heating was performed at 40 ° C. for an energizing time of 120 seconds.
, A short-circuit occurred partially, and 20% peeling was observed at -5 ° C.

[0027]

According to the present invention, the electro-fusion joint can be normally fused in the hot summer weather or in a cold region without changing the power-on time.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of an electrofusion joint of the present invention.

FIG. 2 is a graph showing a relationship between temperature and fusion energy.

FIG. 3 is a block diagram of an electrofusion control device used in a conventional energization time control method.

FIG. 4 is a graph showing a relationship between an ambient temperature of an electric fusion joint and an energization time in a conventional energization time control method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bar code 2 Electric fusion joint 3 Heating wire 4 Terminal pin 5 Connected pipe 10 Electric fusion control device 11 Power supply unit 12 Operation control unit 13 Storage unit 14 Reading means interface 15 Output unit 16 Display 17 Reading means 20 Cable 21 Connector 22 Power supply code

Continuation of front page (72) Inventor Katsuhiko Nishino 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term in Nihon Kokan Co., Ltd. 3H019 GA02 3K092 PP20 QA02 QB02 QB27 QC02 QC18 QC37 RA06 RD12 TT37 UA06 UA19 UC19 4F211 AA04 AD05 AD12 AG08 AH11 AK09 AR11 TA01 TC11 TD07 TH02 TH06 TJ22 TN31 TQ10

Claims (1)

[Claims] 1. An electric resistance wire is provided on the inner surface side of a joint, and when the electric resistance wire is energized to generate heat so as to melt-join the joint and the pipe, a bar code inputting an energizing time attached to the joint is input. The average temperature coefficient (10 ⁻⁶ / K) between 20 and 100 ° C. of the volume resistivity is 1 in the electric fusion joint of the type in which the energization time is controlled by reading the electric current.
An electro-fusion joint characterized by using an electric resistance wire of 000 or more.